dcevm/hotspot/.hg/patches/full-jdk7u11-b21.patch

diff --git a/src/cpu/x86/vm/templateTable_x86_32.cpp b/src/cpu/x86/vm/templateTable_x86_32.cpp
--- a/src/cpu/x86/vm/templateTable_x86_32.cpp
+++ b/src/cpu/x86/vm/templateTable_x86_32.cpp
@@ -2109,6 +2109,22 @@
   // resolve first time through
   address entry;
   switch (bytecode()) {
+    case Bytecodes::_fast_agetfield : // fall through
+    case Bytecodes::_fast_bgetfield : // fall through
+    case Bytecodes::_fast_cgetfield : // fall through
+    case Bytecodes::_fast_dgetfield : // fall through
+    case Bytecodes::_fast_fgetfield : // fall through
+    case Bytecodes::_fast_igetfield : // fall through
+    case Bytecodes::_fast_lgetfield : // fall through
+    case Bytecodes::_fast_sgetfield : // fall through
+    case Bytecodes::_fast_aputfield : // fall through
+    case Bytecodes::_fast_bputfield : // fall through
+    case Bytecodes::_fast_cputfield : // fall through
+    case Bytecodes::_fast_dputfield : // fall through
+    case Bytecodes::_fast_fputfield : // fall through
+    case Bytecodes::_fast_iputfield : // fall through
+    case Bytecodes::_fast_lputfield : // fall through
+    case Bytecodes::_fast_sputfield : // fall through
     case Bytecodes::_getstatic      : // fall through
     case Bytecodes::_putstatic      : // fall through
     case Bytecodes::_getfield       : // fall through
@@ -2203,6 +2219,7 @@
 // Correct values of the cache and index registers are preserved.
 void TemplateTable::jvmti_post_field_access(Register cache,
                                             Register index,
+                                            int byte_no,
                                             bool is_static,
                                             bool has_tos) {
   if (JvmtiExport::can_post_field_access()) {
@@ -2229,7 +2246,11 @@
     // cache: cache entry pointer
     __ call_VM(noreg, CAST_FROM_FN_PTR(address, InterpreterRuntime::post_field_access),
                rax, cache);
-    __ get_cache_and_index_at_bcp(cache, index, 1);
+    
+    // DCEVM: Redefinition might have occured => reresolve the cp entry.
+    __ restore_bcp();
+    resolve_cache_and_index(byte_no, noreg, cache, index, sizeof(u2));
+
     __ bind(L1);
   }
 }
@@ -2250,7 +2271,7 @@
   const Register flags = rax;
 
   resolve_cache_and_index(byte_no, noreg, cache, index, sizeof(u2));
-  jvmti_post_field_access(cache, index, is_static, false);
+  jvmti_post_field_access(cache, index, byte_no, is_static, false);
   load_field_cp_cache_entry(obj, cache, index, off, flags, is_static);
 
   if (!is_static) pop_and_check_object(obj);
@@ -2385,7 +2406,7 @@
 
 // The registers cache and index expected to be set before call.
 // The function may destroy various registers, just not the cache and index registers.
-void TemplateTable::jvmti_post_field_mod(Register cache, Register index, bool is_static) {
+void TemplateTable::jvmti_post_field_mod(Register cache, Register index, int byte_no, bool is_static) {
 
   ByteSize cp_base_offset = constantPoolCacheOopDesc::base_offset();
 
@@ -2443,7 +2464,11 @@
     // rcx: jvalue object on the stack
     __ call_VM(noreg, CAST_FROM_FN_PTR(address, InterpreterRuntime::post_field_modification),
                rbx, rax, rcx);
-    __ get_cache_and_index_at_bcp(cache, index, 1);
+
+    // (tw) Redefinition might have occured => reresolve the cp entry.
+    __ restore_bcp();
+    resolve_cache_and_index(byte_no, noreg, cache, index, sizeof(u2));
+
     __ bind(L1);
   }
 }
@@ -2459,7 +2484,7 @@
   const Register flags = rax;
 
   resolve_cache_and_index(byte_no, noreg, cache, index, sizeof(u2));
-  jvmti_post_field_mod(cache, index, is_static);
+  jvmti_post_field_mod(cache, index, byte_no, is_static);
   load_field_cp_cache_entry(obj, cache, index, off, flags, is_static);
 
   // Doug Lea believes this is not needed with current Sparcs (TSO) and Intel (PSO).
@@ -2697,6 +2722,11 @@
     // rax,: cache entry pointer
     // rcx: jvalue object on the stack
     __ call_VM(noreg, CAST_FROM_FN_PTR(address, InterpreterRuntime::post_field_modification), rbx, rax, rcx);
+
+    // (tw) Redefinition might have occured => reresolve the cp entry.
+    __ restore_bcp();
+    resolve_cache_and_index(2, noreg, rax, rcx, sizeof(u2));
+
     if (bytecode() == Bytecodes::_fast_lputfield) __ pop(rdx);  // restore high value
     __ pop(rax);     // restore lower value
     __ addptr(rsp, sizeof(jvalue));  // release jvalue object space
@@ -2817,6 +2847,11 @@
     // rcx: cache entry pointer
     __ call_VM(noreg, CAST_FROM_FN_PTR(address, InterpreterRuntime::post_field_access), rax, rcx);
     __ pop_ptr(rax);   // restore object pointer
+
+    // DCEVM: Redefinition might have occured => reresolve the cp entry.
+    __ restore_bcp();
+    resolve_cache_and_index(1, noreg, rax, rcx, sizeof(u2));
+
     __ bind(L1);
   }
 
@@ -2987,6 +3022,26 @@
 
   __ bind(notFinal);
 
+  // DCEVM: Check if we are calling an old method (and have to go slow path)
+  Label notOld;
+  __ movl(rax, flags);
+  __ andl(rax, (1 << ConstantPoolCacheEntry::oldMethodBit));
+  __ jcc(Assembler::zero, notOld);
+
+  // Need a null check here!
+  __ null_check(recv);
+
+  // Call out to VM to do look up based on correct vTable version (has to iterate back over the class history of the receiver class)
+  // DCEVM: TODO: Check if we can improve performance by inlining.
+  // DCEVM: TODO: Check if this additional branch affects normal execution time.
+  __ call_VM(method, CAST_FROM_FN_PTR(address, InterpreterRuntime::find_correct_method), recv, index);
+  
+  // profile this call
+  __ profile_final_call(rax);
+  __ jump_from_interpreted(method, rdx);
+
+  __ bind(notOld);
+
   // get receiver klass
   __ null_check(recv, oopDesc::klass_offset_in_bytes());
   // Keep recv in rcx for callee expects it there
@@ -3068,6 +3123,31 @@
   invokevirtual_helper(rbx, rcx, rdx);
   __ bind(notMethod);
 
+  // DCEVM: Check if we are calling an old method (and have to go slow path)
+  //__ movl(rax, rdx);
+  Label notOld;
+  __ andl(rdx, (1 << ConstantPoolCacheEntry::oldMethodBit));
+  __ jcc(Assembler::zero, notOld);
+
+  // Get receiver klass into rdx - also a null check
+  __ movptr(rdx, Address(rcx, oopDesc::klass_offset_in_bytes()));
+  __ verify_oop(rdx);
+
+  // Call out to VM to do look up based on correct vTable version (has to iterate back over the class history of the receiver class)
+  // DCEVM: TODO: Check if we can improve performance by inlining.
+  // DCEVM: TODO: Check if this additional branch affects normal execution time.
+  // DCEVM: TODO: Check the exact semantic (with respect to destoying registers) of call_VM
+  __ call_VM(rbx, CAST_FROM_FN_PTR(address, InterpreterRuntime::find_correct_interface_method), rcx, rax, rbx);
+
+  // DCEVM: TODO: Check if resolved method could be null.
+
+  // profile this call
+  __ profile_virtual_call(rdx, rsi, rdi);
+
+  __ jump_from_interpreted(rbx, rdx);
+
+  __ bind(notOld);
+
   // Get receiver klass into rdx - also a null check
   __ restore_locals();  // restore rdi
   __ load_klass(rdx, rcx);
diff --git a/src/cpu/x86/vm/templateTable_x86_64.cpp b/src/cpu/x86/vm/templateTable_x86_64.cpp
--- a/src/cpu/x86/vm/templateTable_x86_64.cpp
+++ b/src/cpu/x86/vm/templateTable_x86_64.cpp
@@ -2145,6 +2145,22 @@
   // resolve first time through
   address entry;
   switch (bytecode()) {
+  case Bytecodes::_fast_agetfield : // fall through
+  case Bytecodes::_fast_bgetfield : // fall through
+  case Bytecodes::_fast_cgetfield : // fall through
+  case Bytecodes::_fast_dgetfield : // fall through
+  case Bytecodes::_fast_fgetfield : // fall through
+  case Bytecodes::_fast_igetfield : // fall through
+  case Bytecodes::_fast_lgetfield : // fall through
+  case Bytecodes::_fast_sgetfield : // fall through
+  case Bytecodes::_fast_aputfield : // fall through
+  case Bytecodes::_fast_bputfield : // fall through
+  case Bytecodes::_fast_cputfield : // fall through
+  case Bytecodes::_fast_dputfield : // fall through
+  case Bytecodes::_fast_fputfield : // fall through
+  case Bytecodes::_fast_iputfield : // fall through
+  case Bytecodes::_fast_lputfield : // fall through
+  case Bytecodes::_fast_sputfield : // fall through
   case Bytecodes::_getstatic:
   case Bytecodes::_putstatic:
   case Bytecodes::_getfield:
@@ -2251,7 +2267,7 @@
 // The registers cache and index expected to be set before call.
 // Correct values of the cache and index registers are preserved.
 void TemplateTable::jvmti_post_field_access(Register cache, Register index,
-                                            bool is_static, bool has_tos) {
+                                            int byte_no, bool is_static, bool has_tos) {
   // do the JVMTI work here to avoid disturbing the register state below
   // We use c_rarg registers here because we want to use the register used in
   // the call to the VM
@@ -2282,7 +2298,11 @@
     __ call_VM(noreg, CAST_FROM_FN_PTR(address,
                                        InterpreterRuntime::post_field_access),
                c_rarg1, c_rarg2, c_rarg3);
-    __ get_cache_and_index_at_bcp(cache, index, 1);
+    
+    // DCEVM: Redefinition might have occured => reresolve the cp entry.
+    __ restore_bcp();
+    resolve_cache_and_index(byte_no, noreg, cache, index, sizeof(u2));
+
     __ bind(L1);
   }
 }
@@ -2304,7 +2324,7 @@
   const Register bc = c_rarg3; // uses same reg as obj, so don't mix them
 
   resolve_cache_and_index(byte_no, noreg, cache, index, sizeof(u2));
-  jvmti_post_field_access(cache, index, is_static, false);
+  jvmti_post_field_access(cache, index, byte_no, is_static, false);
   load_field_cp_cache_entry(obj, cache, index, off, flags, is_static);
 
   if (!is_static) {
@@ -2438,7 +2458,7 @@
 
 // The registers cache and index expected to be set before call.
 // The function may destroy various registers, just not the cache and index registers.
-void TemplateTable::jvmti_post_field_mod(Register cache, Register index, bool is_static) {
+void TemplateTable::jvmti_post_field_mod(Register cache, Register index, int byte_no, bool is_static) {
   transition(vtos, vtos);
 
   ByteSize cp_base_offset = constantPoolCacheOopDesc::base_offset();
@@ -2491,7 +2511,11 @@
                CAST_FROM_FN_PTR(address,
                                 InterpreterRuntime::post_field_modification),
                c_rarg1, c_rarg2, c_rarg3);
-    __ get_cache_and_index_at_bcp(cache, index, 1);
+
+    // DCEVM: Redefinition might have occured => reresolve the cp entry.
+    __ restore_bcp();
+    resolve_cache_and_index(byte_no, noreg, cache, index, sizeof(u2));
+
     __ bind(L1);
   }
 }
@@ -2507,7 +2531,7 @@
   const Register bc    = c_rarg3;
 
   resolve_cache_and_index(byte_no, noreg, cache, index, sizeof(u2));
-  jvmti_post_field_mod(cache, index, is_static);
+  jvmti_post_field_mod(cache, index, byte_no, is_static);
   load_field_cp_cache_entry(obj, cache, index, off, flags, is_static);
 
   // [jk] not needed currently
@@ -2715,6 +2739,11 @@
                CAST_FROM_FN_PTR(address,
                                 InterpreterRuntime::post_field_modification),
                rbx, c_rarg2, c_rarg3);
+
+    // DCEVM: Redefinition might have occured => reresolve the cp entry.
+    __ restore_bcp();
+    resolve_cache_and_index(2, noreg, rax, rcx, sizeof(u2));
+
     __ pop(rax);     // restore lower value
     __ addptr(rsp, sizeof(jvalue));  // release jvalue object space
     __ bind(L2);
@@ -2815,6 +2844,11 @@
                                 InterpreterRuntime::post_field_access),
                c_rarg1, c_rarg2);
     __ pop_ptr(rax); // restore object pointer
+
+    // DCEVM: Redefinition might have occured => reresolve the cp entry.
+    __ restore_bcp();
+    resolve_cache_and_index(1, noreg, rax, rcx, sizeof(u2));
+
     __ bind(L1);
   }
 
@@ -3030,6 +3064,26 @@
 
   __ bind(notFinal);
 
+  // DCEVM: Check if we are calling an old method (and have to go slow path)
+  Label notOld;
+  __ movl(rax, flags);
+  __ andl(rax, (1 << ConstantPoolCacheEntry::oldMethodBit));
+  __ jcc(Assembler::zero, notOld);
+
+  // Need a null check here!
+  __ null_check(recv);
+
+  // Call out to VM to do look up based on correct vTable version (has to iterate back over the class history of the receiver class)
+  // DCEVM: TODO: Check if we can improve performance by inlining.
+  // DCEVM: TODO: Check if this additional branch affects normal execution time.
+  __ call_VM(method, CAST_FROM_FN_PTR(address, InterpreterRuntime::find_correct_method), recv, index);
+
+  // profile this call
+  __ profile_final_call(rax);
+  __ jump_from_interpreted(method, rdx);
+
+  __ bind(notOld);
+
   // get receiver klass
   __ null_check(recv, oopDesc::klass_offset_in_bytes());
   __ load_klass(rax, recv);
@@ -3113,6 +3167,35 @@
   invokevirtual_helper(rbx, rcx, rdx);
   __ bind(notMethod);
 
+  // DCEVM: Check if we are calling an old method (and have to go slow path)
+  Label notOld;
+  __ andl(rdx, (1 << ConstantPoolCacheEntry::oldMethodBit));
+  __ jcc(Assembler::zero, notOld);
+
+  // Call out to VM to do look up based on correct vTable version (has to iterate back over the class history of the receiver class)
+  // DCEVM: TODO: Check if we can improve performance by inlining.
+  // DCEVM: TODO: Check if this additional branch affects normal execution time.
+  // DCEVM: TODO: Check the exact semantic (with respect to destoying registers) of call_VM
+  // DCEVM: FIXME: What exactly should we store here?
+  __ push(rcx); // destroyed by Linux arguments passing conventions
+  __ movptr(r14, rcx);
+  __ call_VM(rbx, CAST_FROM_FN_PTR(address, InterpreterRuntime::find_correct_interface_method), r14, rax, rbx);
+  __ pop(rcx);
+
+  // Get receiver klass into rdx - also a null check
+  __ restore_locals(); // restore r14
+  __ load_klass(rdx, rcx);
+  __ verify_oop(rdx);
+
+  // DCEVM: TODO: Check if resolved method could be null.
+
+  // profile this call
+  __ profile_virtual_call(rdx, r13, r14);
+
+  __ jump_from_interpreted(rbx, rdx);
+
+  __ bind(notOld);
+
   // Get receiver klass into rdx - also a null check
   __ restore_locals(); // restore r14
   __ load_klass(rdx, rcx);
diff --git a/src/share/vm/c1/c1_Compilation.hpp b/src/share/vm/c1/c1_Compilation.hpp
--- a/src/share/vm/c1/c1_Compilation.hpp
+++ b/src/share/vm/c1/c1_Compilation.hpp
@@ -239,8 +239,8 @@
 #define BAILOUT(msg)               { bailout(msg); return;              }
 #define BAILOUT_(msg, res)         { bailout(msg); return res;          }
 
-#define CHECK_BAILOUT()            { if (bailed_out()) return;          }
-#define CHECK_BAILOUT_(res)        { if (bailed_out()) return res;      }
+#define CHECK_BAILOUT()            { if (((CompilerThread *)Thread::current())->should_bailout()) bailout("Aborted externally"); if (bailed_out()) return;          }
+#define CHECK_BAILOUT_(res)        { if (((CompilerThread *)Thread::current())->should_bailout()) bailout("Aborted externally"); if (bailed_out()) return res;      }
 
 
 class InstructionMark: public StackObj {
diff --git a/src/share/vm/ci/ciEnv.cpp b/src/share/vm/ci/ciEnv.cpp
--- a/src/share/vm/ci/ciEnv.cpp
+++ b/src/share/vm/ci/ciEnv.cpp
@@ -1181,3 +1181,11 @@
   // If memory is low, we stop compiling methods.
   record_method_not_compilable("out of memory");
 }
+
+// DCEVM: Called after class redefinition to clean up possibly invalidated state.
+void ciEnv::cleanup_after_redefinition() {
+
+  if (_factory != NULL) {
+    _factory->cleanup_after_redefinition();
+  }
+}
diff --git a/src/share/vm/ci/ciEnv.hpp b/src/share/vm/ci/ciEnv.hpp
--- a/src/share/vm/ci/ciEnv.hpp
+++ b/src/share/vm/ci/ciEnv.hpp
@@ -419,6 +419,8 @@
   void record_failure(const char* reason);
   void record_method_not_compilable(const char* reason, bool all_tiers = true);
   void record_out_of_memory_failure();
+
+  void cleanup_after_redefinition();
 };
 
 #endif // SHARE_VM_CI_CIENV_HPP
diff --git a/src/share/vm/ci/ciObjectFactory.cpp b/src/share/vm/ci/ciObjectFactory.cpp
--- a/src/share/vm/ci/ciObjectFactory.cpp
+++ b/src/share/vm/ci/ciObjectFactory.cpp
@@ -294,6 +294,11 @@
       // into the table.  We need to recompute our index.
       index = find(keyHandle(), _ci_objects);
     }
+
+    if (is_found_at(index, keyHandle(), _ci_objects)) {
+      // DCEVM: Check if this is an error? Can occur when redefining classes.
+      return _ci_objects->at(index);
+    }
     assert(!is_found_at(index, keyHandle(), _ci_objects), "no double insert");
     insert(index, new_object, _ci_objects);
     return new_object;
@@ -758,3 +763,50 @@
              _unloaded_instances->length(),
              _unloaded_klasses->length());
 }
+
+// DCEVM: Resoring the ciObject arrays after class redefinition
+void ciObjectFactory::sort_ci_objects(GrowableArray<ciObject*>* objects) {
+
+  // Resort the _ci_objects array. The order of two class pointers can be changed during class redefinition.
+  oop last = NULL;
+  for (int j = 0; j< objects->length(); j++) {
+    oop o = objects->at(j)->get_oop();
+    if (last >= o) {
+      int cur_last_index = j - 1;
+      oop cur_last = last;
+      while (cur_last >= o) {
+
+        // Swap the two objects to guarantee ordering
+        ciObject *tmp = objects->at(cur_last_index);
+        objects->at_put(cur_last_index, objects->at(cur_last_index + 1));
+        objects->at_put(cur_last_index + 1, tmp);
+
+        // Decrement index to move one step to the left
+        cur_last_index--;
+        if (cur_last_index < 0) {
+          break;
+        }
+        cur_last = objects->at(cur_last_index)->get_oop();
+      }
+    } else {
+      assert(last < o, "out of order");
+      last = o;  
+    }
+  }
+
+#ifdef ASSERT
+  if (CIObjectFactoryVerify) {
+    oop last = NULL;
+    for (int j = 0; j< objects->length(); j++) {
+      oop o = objects->at(j)->get_oop();
+      assert(last < o, "out of order");
+      last = o;
+    }
+  }
+#endif // ASSERT
+}
+
+// DCEVM: Called after class redefinition to clean up possibly invalidated state.
+void ciObjectFactory::cleanup_after_redefinition() {
+  sort_ci_objects(_ci_objects);
+}
diff --git a/src/share/vm/ci/ciObjectFactory.hpp b/src/share/vm/ci/ciObjectFactory.hpp
--- a/src/share/vm/ci/ciObjectFactory.hpp
+++ b/src/share/vm/ci/ciObjectFactory.hpp
@@ -38,6 +38,7 @@
 class ciObjectFactory : public ResourceObj {
   friend class VMStructs;
   friend class ciEnv;
+  friend class CompileBroker;
 
 private:
   static volatile bool _initialized;
@@ -137,6 +138,11 @@
 
   void print_contents();
   void print();
+
+private:
+
+  static void sort_ci_objects(GrowableArray<ciObject*>* objects);
+  void cleanup_after_redefinition();
 };
 
 #endif // SHARE_VM_CI_CIOBJECTFACTORY_HPP
diff --git a/src/share/vm/classfile/classFileParser.cpp b/src/share/vm/classfile/classFileParser.cpp
--- a/src/share/vm/classfile/classFileParser.cpp
+++ b/src/share/vm/classfile/classFileParser.cpp
@@ -787,6 +787,7 @@
                                                  Handle class_loader,
                                                  Handle protection_domain,
                                                  Symbol* class_name,
+                                                 KlassHandle old_klass,
                                                  TRAPS) {
   ClassFileStream* cfs = stream();
   assert(length > 0, "only called for length>0");
@@ -805,6 +806,9 @@
       interface_index, CHECK_(nullHandle));
     if (cp->tag_at(interface_index).is_klass()) {
       interf = KlassHandle(THREAD, cp->resolved_klass_at(interface_index));
+      if (!old_klass.is_null() && !interf->is_newest_version()) {
+        interf = KlassHandle(THREAD, interf->newest_version());
+      }
     } else {
       Symbol*  unresolved_klass  = cp->klass_name_at(interface_index);
 
@@ -817,6 +821,9 @@
       klassOop k = SystemDictionary::resolve_super_or_fail(class_name,
                     unresolved_klass, class_loader, protection_domain,
                     false, CHECK_(nullHandle));
+      if (!old_klass.is_null()) {
+        k = k->klass_part()->newest_version();
+      }
       interf = KlassHandle(THREAD, k);
 
       if (LinkWellKnownClasses)  // my super type is well known to me
@@ -1705,6 +1712,8 @@
   int runtime_invisible_parameter_annotations_length = 0;
   u1* annotation_default = NULL;
   int annotation_default_length = 0;
+  u2 code_section_table_length;
+  typeArrayHandle code_section_table;
 
   // Parse code and exceptions attribute
   u2 method_attributes_count = cfs->get_u2_fast();
@@ -1874,6 +1883,24 @@
             parse_stackmap_table(code_attribute_length, CHECK_(nullHandle));
           stackmap_data = typeArrayHandle(THREAD, sm);
           parsed_stackmap_attribute = true;
+        } else if (UseMethodForwardPoints && cp->symbol_at(code_attribute_name_index) == vmSymbols::tag_code_sections()) {
+          int length = code_attribute_length;
+          int value_count = length / sizeof(u2);
+          int line_count = length / 3;
+          if (TraceRedefineClasses >= 3) {
+            tty->print_cr("Found code section attribute when loading class with %d entries", value_count, line_count);
+          }
+          code_section_table_length = value_count;
+          code_section_table = oopFactory::new_permanent_shortArray(value_count, CHECK_NULL);
+          code_section_table->set_length(value_count);
+
+          for (int i = 0; i < value_count; ++i) {
+            u2 value = cfs->get_u2(CHECK_(nullHandle));
+            code_section_table->short_at_put(i, value);
+            if (TraceRedefineClasses >= 4) {
+              tty->print_cr("Code section table at %d: %d", i, value);
+            }
+          }
         } else {
           // Skip unknown attributes
           cfs->skip_u1(code_attribute_length, CHECK_(nullHandle));
@@ -1994,6 +2021,18 @@
   }
 #endif
 
+  // DCEVM: TODO: Get a different solution for the problem of method forward
+  // points and variable sized interpreter frames.
+  if (UseMethodForwardPoints) {
+    if (max_stack > MethodForwardPointsMaxStack) {
+      fatal(err_msg("Method has too large stack (%d), increase the value of MethodForwardPointsMaxStack (%d)", max_stack, MethodForwardPointsMaxStack));
+    }
+    if (max_locals > MethodForwardPointsMaxLocals) {
+      fatal(err_msg("Method has too many locals (%d), increase the value of MethodForwardPointsMaxLocals (%d)", max_stack, MethodForwardPointsMaxStack));
+    }
+    max_stack = MethodForwardPointsMaxStack;
+    max_locals = MethodForwardPointsMaxLocals;
+  }
   // Fill in code attribute information
   m->set_max_stack(max_stack);
   m->set_max_locals(max_locals);
@@ -2008,6 +2047,8 @@
    */
   m->set_exception_table(exception_handlers());
 
+  m->constMethod()->set_code_section_table(code_section_table());
+
   // Copy byte codes
   m->set_code(code_start);
 
@@ -2543,6 +2584,24 @@
           "Invalid Deprecated classfile attribute length %u in class file %s",
           attribute_length, CHECK);
       }
+    // DCEVM: Check for deleted field attribute
+    } else if (tag == vmSymbols::tag_field_redefinition_policy()) {
+
+      char field_redefinition_policy = cfs->get_u1_fast();
+	  k->set_field_redefinition_policy(field_redefinition_policy);
+
+	  // DCEVM: Check for deleted static field attribute
+	} else if (tag == vmSymbols::tag_static_field_redefinition_policy()) {
+
+		char static_field_redefinition_policy = cfs->get_u1_fast();
+		k->set_static_field_redefinition_policy(static_field_redefinition_policy);
+
+    // DCEVM: Check for deleted method attribute
+    } else if (tag == vmSymbols::tag_method_redefinition_policy()) {
+
+      char method_redefinition_policy = cfs->get_u1_fast();
+      k->set_method_redefinition_policy(method_redefinition_policy);
+
     } else if (_major_version >= JAVA_1_5_VERSION) {
       if (tag == vmSymbols::tag_signature()) {
         if (attribute_length != 2) {
@@ -2634,9 +2693,126 @@
 }
 
 
+// DCEVM: Finds the super symbols by reading the bytes of the class and returns
+// them in a growable array.
+void ClassFileParser::findSuperSymbols(Symbol* name,
+                          Handle class_loader,
+                          Handle protection_domain,
+                          KlassHandle old_klass,
+                          GrowableArray<Symbol*> &handles,
+                          TRAPS) {
+  
+  _cp_patches = NULL;
+  // So that JVMTI can cache class file in the state before retransformable agents
+  // have modified it
+  unsigned char *cached_class_file_bytes = NULL;
+
+  ClassFileStream* cfs = stream();
+
+  _has_finalizer = _has_empty_finalizer = _has_vanilla_constructor = false;
+
+  instanceKlassHandle nullHandle;
+
+  // Save the class file name for easier error message printing.
+  _class_name = name != NULL ? name : vmSymbols::unknown_class_name();
+
+  cfs->guarantee_more(8, CHECK);  // magic, major, minor
+  // Magic value
+  u4 magic = cfs->get_u4_fast();
+  if (magic != JAVA_CLASSFILE_MAGIC) {
+    // Invalid class file!
+    return;
+  }
+
+  // Version numbers
+  u2 minor_version = cfs->get_u2_fast();
+  u2 major_version = cfs->get_u2_fast();
+
+  // Check version numbers - we check this even with verifier off
+  if (!is_supported_version(major_version, minor_version)) {
+    
+    // Unsupported version!
+    return;
+  }
+
+  _major_version = major_version;
+  _minor_version = minor_version;
+
+
+  // Check if verification needs to be relaxed for this class file
+  // Do not restrict it to jdk1.0 or jdk1.1 to maintain backward compatibility (4982376)
+  _relax_verify = Verifier::relax_verify_for(class_loader());
+  _need_verify = false;
+
+  // Constant pool
+  constantPoolHandle cp = parse_constant_pool(CHECK);
+  int cp_size = cp->length();
+
+  cfs->guarantee_more(8, CHECK);  // flags, this_class, super_class, infs_len
+
+  // Access flags
+  AccessFlags access_flags;
+  jint flags = cfs->get_u2_fast() & JVM_RECOGNIZED_CLASS_MODIFIERS;
+
+  if ((flags & JVM_ACC_INTERFACE) && _major_version < JAVA_6_VERSION) {
+    // Set abstract bit for old class files for backward compatibility
+    flags |= JVM_ACC_ABSTRACT;
+  }
+  access_flags.set_flags(flags);
+
+  // This class and superclass
+  instanceKlassHandle super_klass;
+  u2 this_class_index = cfs->get_u2_fast();
+  check_property(
+    valid_cp_range(this_class_index, cp_size) &&
+    cp->tag_at(this_class_index).is_unresolved_klass(),
+    "Invalid this class index %u in constant pool in class file %s",
+    this_class_index, CHECK);
+
+  Symbol* class_name = cp->unresolved_klass_at(this_class_index);
+  assert(class_name != NULL, "class_name can't be null");
+
+  // Update _class_name which could be null previously to be class_name
+  _class_name = class_name;
+
+  // DCEVM: DO NOT release all handles when parsing is done
+  {// HandleMark hm(THREAD);
+
+    // Checks if name in class file matches requested name
+    if (name != NULL && class_name != name) {
+      return;
+    }
+
+    u2 super_class_index = cfs->get_u2_fast();
+
+    if (super_class_index != 0) {
+      Symbol* super_class = cp->klass_name_at(super_class_index);
+      handles.append(super_class);
+    } else {
+      // DCEVM: This redefinition must be for the Object class.
+    }
+
+    // Interfaces
+    u2 itfs_len = cfs->get_u2_fast();
+    objArrayHandle local_interfaces;
+    if (itfs_len == 0) {
+      local_interfaces = objArrayHandle(THREAD, Universe::the_empty_system_obj_array());
+    } else {
+      local_interfaces = parse_interfaces(cp, itfs_len, class_loader, protection_domain, _class_name, old_klass, CHECK);
+    }
+
+    for (int i=0; i<local_interfaces->length(); i++) {
+      oop o = local_interfaces->obj_at(i);
+      Symbol* interface_handle = ((klassOop)o)->klass_part()->name();
+      handles.append(interface_handle);
+    }
+  }
+}
+
 instanceKlassHandle ClassFileParser::parseClassFile(Symbol* name,
                                                     Handle class_loader,
                                                     Handle protection_domain,
+                                                    KlassHandle old_klass,
                                                     KlassHandle host_klass,
                                                     GrowableArray<Handle>* cp_patches,
                                                     TempNewSymbol& parsed_name,
@@ -2688,10 +2864,13 @@
     unsigned char* ptr = cfs->buffer();
     unsigned char* end_ptr = cfs->buffer() + cfs->length();
 
+    bool pretend_new_universe = Thread::current()->pretend_new_universe();
+    Thread::current()->set_pretend_new_universe(false);
     JvmtiExport::post_class_file_load_hook(name, class_loader, protection_domain,
                                            &ptr, &end_ptr,
                                            &cached_class_file_bytes,
                                            &cached_class_file_length);
+    Thread::current()->set_pretend_new_universe(pretend_new_universe);
 
     if (ptr != cfs->buffer()) {
       // JVMTI agent has modified class file data.
@@ -2847,7 +3026,11 @@
       // However, make sure it is not an array type.
       bool is_array = false;
       if (cp->tag_at(super_class_index).is_klass()) {
-        super_klass = instanceKlassHandle(THREAD, cp->resolved_klass_at(super_class_index));
+        klassOop resolved_klass = cp->resolved_klass_at(super_class_index);
+        if (!old_klass.is_null()) {
+          resolved_klass = resolved_klass->klass_part()->newest_version();
+        }
+        super_klass = instanceKlassHandle(THREAD, resolved_klass);
         if (_need_verify)
           is_array = super_klass->oop_is_array();
       } else if (_need_verify) {
@@ -2865,7 +3048,7 @@
     if (itfs_len == 0) {
       local_interfaces = objArrayHandle(THREAD, Universe::the_empty_system_obj_array());
     } else {
-      local_interfaces = parse_interfaces(cp, itfs_len, class_loader, protection_domain, _class_name, CHECK_(nullHandle));
+      local_interfaces = parse_interfaces(cp, itfs_len, class_loader, protection_domain, _class_name, old_klass, CHECK_(nullHandle));
     }
 
     u2 java_fields_count = 0;
@@ -2912,7 +3095,9 @@
                                                            protection_domain,
                                                            true,
                                                            CHECK_(nullHandle));
-
+      if (!old_klass.is_null()) {
+        k = k->klass_part()->newest_version();
+      }
       KlassHandle kh (THREAD, k);
       super_klass = instanceKlassHandle(THREAD, kh());
       if (LinkWellKnownClasses)  // my super class is well known to me
@@ -3303,6 +3488,19 @@
       rt = REF_NONE;
     } else {
       rt = super_klass->reference_type();
+
+      // DCEVM: With class redefinition, it can also happen that special classes are loaded.
+      if (name == vmSymbols::java_lang_ref_Reference()) {
+        rt = REF_OTHER;
+      } else if (name == vmSymbols::java_lang_ref_SoftReference()) {
+        rt = REF_SOFT;
+      } else if (name == vmSymbols::java_lang_ref_WeakReference()) {
+        rt = REF_WEAK;
+      } else if (name == vmSymbols::java_lang_ref_FinalReference()) {
+        rt = REF_FINAL;
+      } else if (name == vmSymbols::java_lang_ref_PhantomReference()) {
+        rt = REF_PHANTOM;
+      }
     }
 
     // We can now create the basic klassOop for this klass
@@ -3402,7 +3600,7 @@
     // Do final class setup
     fill_oop_maps(this_klass, nonstatic_oop_map_count, nonstatic_oop_offsets, nonstatic_oop_counts);
 
-    set_precomputed_flags(this_klass);
+    set_precomputed_flags(this_klass, old_klass);
 
     // reinitialize modifiers, using the InnerClasses attribute
     int computed_modifiers = this_klass->compute_modifier_flags(CHECK_(nullHandle));
@@ -3425,6 +3623,10 @@
     // Allocate mirror and initialize static fields
     java_lang_Class::create_mirror(this_klass, CHECK_(nullHandle));
 
+    if (rt == REF_OTHER) {
+      instanceRefKlass::update_nonstatic_oop_maps(ik);
+    }
+
     ClassLoadingService::notify_class_loaded(instanceKlass::cast(this_klass()),
                                              false /* not shared class */);
 
@@ -3567,7 +3769,7 @@
 }
 
 
-void ClassFileParser::set_precomputed_flags(instanceKlassHandle k) {
+void ClassFileParser::set_precomputed_flags(instanceKlassHandle k, KlassHandle old_klass) {
   klassOop super = k->super();
 
   // Check if this klass has an empty finalize method (i.e. one with return bytecode only),
@@ -3575,7 +3777,9 @@
   if (!_has_empty_finalizer) {
     if (_has_finalizer ||
         (super != NULL && super->klass_part()->has_finalizer())) {
-      k->set_has_finalizer();
+      if (old_klass.is_null() || old_klass->has_finalizer()) {
+        k->set_has_finalizer();
+      }
     }
   }
 
@@ -3591,7 +3795,7 @@
 
   // Check if this klass supports the java.lang.Cloneable interface
   if (SystemDictionary::Cloneable_klass_loaded()) {
-    if (k->is_subtype_of(SystemDictionary::Cloneable_klass())) {
+    if (k->is_subtype_of(SystemDictionary::Cloneable_klass()) || k->is_subtype_of(SystemDictionary::Cloneable_klass()->klass_part()->newest_version())) {
       k->set_is_cloneable();
     }
   }
diff --git a/src/share/vm/classfile/classFileParser.hpp b/src/share/vm/classfile/classFileParser.hpp
--- a/src/share/vm/classfile/classFileParser.hpp
+++ b/src/share/vm/classfile/classFileParser.hpp
@@ -78,6 +78,7 @@
                                   Handle class_loader,
                                   Handle protection_domain,
                                   Symbol* class_name,
+                                  KlassHandle old_klass,
                                   TRAPS);
 
   // Field parsing
@@ -151,7 +152,7 @@
                      unsigned int nonstatic_oop_map_count,
                      int* nonstatic_oop_offsets,
                      unsigned int* nonstatic_oop_counts);
-  void set_precomputed_flags(instanceKlassHandle k);
+  void set_precomputed_flags(instanceKlassHandle k, KlassHandle old_klass);
   objArrayHandle compute_transitive_interfaces(instanceKlassHandle super,
                                                objArrayHandle local_ifs, TRAPS);
 
@@ -263,21 +264,33 @@
   instanceKlassHandle parseClassFile(Symbol* name,
                                      Handle class_loader,
                                      Handle protection_domain,
+                                     KlassHandle old_klass,
                                      TempNewSymbol& parsed_name,
                                      bool verify,
                                      TRAPS) {
     KlassHandle no_host_klass;
-    return parseClassFile(name, class_loader, protection_domain, no_host_klass, NULL, parsed_name, verify, THREAD);
+    return parseClassFile(name, class_loader, protection_domain, old_klass, no_host_klass, NULL, parsed_name, verify, THREAD);
   }
   instanceKlassHandle parseClassFile(Symbol* name,
                                      Handle class_loader,
                                      Handle protection_domain,
+                                     KlassHandle old_klass,
                                      KlassHandle host_klass,
                                      GrowableArray<Handle>* cp_patches,
                                      TempNewSymbol& parsed_name,
                                      bool verify,
                                      TRAPS);
 
+  static void initialize_static_field(fieldDescriptor* fd, TRAPS);
+
+  // DCEVM: Creates symbol handles for the super class and the interfaces
+  void findSuperSymbols(Symbol* name,
+                        Handle class_loader,
+                        Handle protection_domain,
+                        KlassHandle old_klass,
+                        GrowableArray<Symbol*> &handles,
+                        TRAPS);
+
   // Verifier checks
   static void check_super_class_access(instanceKlassHandle this_klass, TRAPS);
   static void check_super_interface_access(instanceKlassHandle this_klass, TRAPS);
diff --git a/src/share/vm/classfile/classLoader.cpp b/src/share/vm/classfile/classLoader.cpp
--- a/src/share/vm/classfile/classLoader.cpp
+++ b/src/share/vm/classfile/classLoader.cpp
@@ -915,6 +915,7 @@
     instanceKlassHandle result = parser.parseClassFile(h_name,
                                                        class_loader,
                                                        protection_domain,
+                                                       KlassHandle(),
                                                        parsed_name,
                                                        false,
                                                        CHECK_(h));
diff --git a/src/share/vm/classfile/dictionary.cpp b/src/share/vm/classfile/dictionary.cpp
--- a/src/share/vm/classfile/dictionary.cpp
+++ b/src/share/vm/classfile/dictionary.cpp
@@ -326,6 +326,21 @@
   }
 }
 
+
+// DCEVM: Just the classes from defining class loaders
+void Dictionary::classes_do(ObjectClosure *closure) {
+  for (int index = 0; index < table_size(); index++) {
+    for (DictionaryEntry* probe = bucket(index);
+      probe != NULL;
+      probe = probe->next()) {
+        klassOop k = probe->klass();
+        if (probe->loader() == instanceKlass::cast(k)->class_loader()) {
+          closure->do_object(k);
+        }
+    }
+  }
+}
+
 // Added for initialize_itable_for_klass to handle exceptions
 //   Just the classes from defining class loaders
 void Dictionary::classes_do(void f(klassOop, TRAPS), TRAPS) {
@@ -433,6 +448,33 @@
   add_entry(index, entry);
 }
 
+// DCEVM: Updates the klass entry to point to the new klassOop. Necessary only for class redefinition.
+bool Dictionary::update_klass(int index, unsigned int hash, Symbol* name, Handle loader, KlassHandle k, KlassHandle old_class) {
+
+  // There are several entries for the same class in the dictionary: One extra entry for each parent classloader of the classloader of the class.
+  bool found = false;
+  for (int index = 0; index < table_size(); index++) {
+    for (DictionaryEntry* entry = bucket(index); entry != NULL; entry = entry->next()) {
+      if (entry->klass() == old_class()) {
+        entry->set_literal(k());
+        found = true;
+      }
+    }
+  }
+
+  return found;
+}
+
+// DCEVM: Undo previous updates to the system dictionary
+void Dictionary::rollback_redefinition() {
+  for (int index = 0; index < table_size(); index++) {
+    for (DictionaryEntry* entry = bucket(index); entry != NULL; entry = entry->next()) {
+      if (entry->klass()->klass_part()->is_redefining()) {
+        entry->set_literal(entry->klass()->klass_part()->old_version());
+      }
+    }
+  }
+}
 
 // This routine does not lock the system dictionary.
 //
@@ -459,12 +501,22 @@
   return NULL;
 }
 
+// DCEVM: return old version if we are not in the new universe?
+klassOop Dictionary::intercept_for_version(klassOop k) {
+  if (k == NULL) return k;
+
+  if (k->klass_part()->is_redefining() && !Thread::current()->pretend_new_universe()) {
+    return k->klass_part()->old_version();
+  }
+
+  return k;
+}
 
 klassOop Dictionary::find(int index, unsigned int hash, Symbol* name,
                           Handle loader, Handle protection_domain, TRAPS) {
   DictionaryEntry* entry = get_entry(index, hash, name, loader);
   if (entry != NULL && entry->is_valid_protection_domain(protection_domain)) {
-    return entry->klass();
+    return intercept_for_version(entry->klass());
   } else {
     return NULL;
   }
@@ -477,7 +529,7 @@
   assert (index == index_for(name, loader), "incorrect index?");
 
   DictionaryEntry* entry = get_entry(index, hash, name, loader);
-  return (entry != NULL) ? entry->klass() : (klassOop)NULL;
+  return intercept_for_version((entry != NULL) ? entry->klass() : (klassOop)NULL);
 }
 
 
@@ -489,7 +541,7 @@
   assert (index == index_for(name, Handle()), "incorrect index?");
 
   DictionaryEntry* entry = get_entry(index, hash, name, Handle());
-  return (entry != NULL) ? entry->klass() : (klassOop)NULL;
+  return intercept_for_version((entry != NULL) ? entry->klass() : (klassOop)NULL);
 }
 
 
diff --git a/src/share/vm/classfile/dictionary.hpp b/src/share/vm/classfile/dictionary.hpp
--- a/src/share/vm/classfile/dictionary.hpp
+++ b/src/share/vm/classfile/dictionary.hpp
@@ -73,6 +73,10 @@
 
   void add_klass(Symbol* class_name, Handle class_loader,KlassHandle obj);
 
+  bool update_klass(int index, unsigned int hash, Symbol* name, Handle loader, KlassHandle k, KlassHandle old_class);
+
+  void rollback_redefinition();
+
   klassOop find_class(int index, unsigned int hash,
                       Symbol* name, Handle loader);
 
@@ -89,6 +93,7 @@
   void classes_do(void f(klassOop, TRAPS), TRAPS);
   void classes_do(void f(klassOop, oop));
   void classes_do(void f(klassOop, oop, TRAPS), TRAPS);
+  void classes_do(ObjectClosure *closure);
 
   void methods_do(void f(methodOop));
 
@@ -105,6 +110,7 @@
   bool do_unloading(BoolObjectClosure* is_alive);
 
   // Protection domains
+  static klassOop intercept_for_version(klassOop k);
   klassOop find(int index, unsigned int hash, Symbol* name,
                 Handle loader, Handle protection_domain, TRAPS);
   bool is_valid_protection_domain(int index, unsigned int hash,
diff --git a/src/share/vm/classfile/javaClasses.cpp b/src/share/vm/classfile/javaClasses.cpp
--- a/src/share/vm/classfile/javaClasses.cpp
+++ b/src/share/vm/classfile/javaClasses.cpp
@@ -1783,7 +1783,7 @@
   klassOop klass = SystemDictionary::reflect_Method_klass();
   // This class is eagerly initialized during VM initialization, since we keep a refence
   // to one of the methods
-  assert(instanceKlass::cast(klass)->is_initialized(), "must be initialized");
+  assert(instanceKlass::cast(klass)->is_initialized() || klass->klass_part()->old_version() != NULL, "must be initialized");
   return instanceKlass::cast(klass)->allocate_instance_handle(CHECK_NH);
 }
 
diff --git a/src/share/vm/classfile/javaClasses.hpp b/src/share/vm/classfile/javaClasses.hpp
--- a/src/share/vm/classfile/javaClasses.hpp
+++ b/src/share/vm/classfile/javaClasses.hpp
@@ -213,7 +213,6 @@
 
 class java_lang_Class : AllStatic {
   friend class VMStructs;
-
  private:
   // The fake offsets are added by the class loader when java.lang.Class is loaded
 
diff --git a/src/share/vm/classfile/loaderConstraints.cpp b/src/share/vm/classfile/loaderConstraints.cpp
--- a/src/share/vm/classfile/loaderConstraints.cpp
+++ b/src/share/vm/classfile/loaderConstraints.cpp
@@ -449,7 +449,7 @@
         if (k != NULL) {
           // We found the class in the system dictionary, so we should
           // make sure that the klassOop matches what we already have.
-          guarantee(k == probe->klass(), "klass should be in dictionary");
+          guarantee(k == probe->klass()->klass_part()->newest_version(), "klass should be in dictionary");
         } else {
           // If we don't find the class in the system dictionary, it
           // has to be in the placeholders table.
diff --git a/src/share/vm/classfile/loaderConstraints.hpp b/src/share/vm/classfile/loaderConstraints.hpp
--- a/src/share/vm/classfile/loaderConstraints.hpp
+++ b/src/share/vm/classfile/loaderConstraints.hpp
@@ -106,7 +106,7 @@
 
   klassOop klass() { return literal(); }
   klassOop* klass_addr() { return literal_addr(); }
-  void set_klass(klassOop k) { set_literal(k); }
+  void set_klass(klassOop k) { set_literal(k); assert(k == NULL || !k->klass_part()->is_redefining(), "just checking"); }
 
   LoaderConstraintEntry* next() {
     return (LoaderConstraintEntry*)HashtableEntry<klassOop>::next();
diff --git a/src/share/vm/classfile/systemDictionary.cpp b/src/share/vm/classfile/systemDictionary.cpp
--- a/src/share/vm/classfile/systemDictionary.cpp
+++ b/src/share/vm/classfile/systemDictionary.cpp
@@ -151,6 +151,7 @@
     // can return a null klass
     klass = handle_resolution_exception(class_name, class_loader, protection_domain, throw_error, k_h, THREAD);
   }
+  assert(klass == NULL || klass->klass_part()->is_newest_version() || klass->klass_part()->newest_version()->klass_part()->is_redefining(), "must be");
   return klass;
 }
 
@@ -193,7 +194,8 @@
 // Forwards to resolve_instance_class_or_null
 
 klassOop SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
-  assert(!THREAD->is_Compiler_thread(), "Can not load classes with the Compiler thread");
+  // DCEVM: Check if this relaxing of the condition is correct? Test case hs203t004 failing otherwise.
+  assert(!THREAD->is_Compiler_thread() || JvmtiThreadState::state_for(JavaThread::current())->get_class_being_redefined() != NULL, "Can not load classes with the Compiler thread");
   if (FieldType::is_array(class_name)) {
     return resolve_array_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
   } else if (FieldType::is_obj(class_name)) {
@@ -997,6 +999,7 @@
   instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
                                                              class_loader,
                                                              protection_domain,
+                                                             KlassHandle(),
                                                              host_klass,
                                                              cp_patches,
                                                              parsed_name,
@@ -1056,8 +1059,15 @@
                                                Handle protection_domain,
                                                ClassFileStream* st,
                                                bool verify,
+                                               KlassHandle old_class,
                                                TRAPS) {
 
+  bool redefine_classes_locked = false;
+  if (!Thread::current()->redefine_classes_mutex()->owned_by_self()) {
+    Thread::current()->redefine_classes_mutex()->lock();
+    redefine_classes_locked = true;
+  }
+  
   // Classloaders that support parallelism, e.g. bootstrap classloader,
   // or all classloaders with UnsyncloadClass do not acquire lock here
   bool DoObjectLock = true;
@@ -1085,9 +1095,14 @@
   instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
                                                              class_loader,
                                                              protection_domain,
+                                                             old_class,
                                                              parsed_name,
                                                              verify,
                                                              THREAD);
+  if (!old_class.is_null() && !k.is_null()) {
+    k->set_redefining(true);
+    k->set_old_version(old_class());
+  }
 
   const char* pkg = "java/";
   if (!HAS_PENDING_EXCEPTION &&
@@ -1122,13 +1137,18 @@
     // Add class just loaded
     // If a class loader supports parallel classloading handle parallel define requests
     // find_or_define_instance_class may return a different instanceKlass
-    if (is_parallelCapable(class_loader)) {
+    // (tw) TODO: for class redefinition the parallel version does not work, check if this is a problem?
+    if (is_parallelCapable(class_loader) && old_class.is_null()) {
       k = find_or_define_instance_class(class_name, class_loader, k, THREAD);
     } else {
-      define_instance_class(k, THREAD);
+      define_instance_class(k, old_class, THREAD);
     }
   }
 
+  if (redefine_classes_locked) {
+    Thread::current()->redefine_classes_mutex()->unlock();
+  }
+
   // If parsing the class file or define_instance_class failed, we
   // need to remove the placeholder added on our behalf. But we
   // must make sure parsed_name is valid first (it won't be if we had
@@ -1157,7 +1177,7 @@
       MutexLocker mu(SystemDictionary_lock, THREAD);
 
       klassOop check = find_class(parsed_name, class_loader);
-      assert(check == k(), "should be present in the dictionary");
+      assert((check == k() && !k->is_redefining()) || (k->is_redefining() && check == k->old_version()), "should be present in the dictionary");
 
       klassOop check2 = find_class(h_name, h_loader);
       assert(check == check2, "name inconsistancy in SystemDictionary");
@@ -1453,7 +1473,11 @@
   }
 }
 
-void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) {
+void SystemDictionary::rollback_redefinition() {
+  dictionary()->rollback_redefinition();
+}
+
+void SystemDictionary::define_instance_class(instanceKlassHandle k, KlassHandle old_class, TRAPS) {
 
   Handle class_loader_h(THREAD, k->class_loader());
 
@@ -1480,13 +1504,23 @@
   Symbol*  name_h = k->name();
   unsigned int d_hash = dictionary()->compute_hash(name_h, class_loader_h);
   int d_index = dictionary()->hash_to_index(d_hash);
-  check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK);
+
+  // DCEVM: Update version of the klassOop in the system dictionary
+  // TODO: Check for thread safety!
+  if (!old_class.is_null()) {
+    bool ok = dictionary()->update_klass(d_index, d_hash, name_h, class_loader_h, k, old_class);
+    assert (ok, "must have found old class and updated!");
+  }
+  check_constraints(d_index, d_hash, k, class_loader_h, old_class.is_null(), CHECK);
+
+  if(!old_class.is_null() && TraceRedefineClasses >= 3){ tty->print_cr("Class has been updated!"); }
 
   // Register class just loaded with class loader (placed in Vector)
   // Note we do this before updating the dictionary, as this can
   // fail with an OutOfMemoryError (if it does, we will *not* put this
   // class in the dictionary and will not update the class hierarchy).
-  if (k->class_loader() != NULL) {
+  // (tw) Only register if not redefining a class.
+  if (k->class_loader() != NULL && old_class.is_null()) {
     methodHandle m(THREAD, Universe::loader_addClass_method());
     JavaValue result(T_VOID);
     JavaCallArguments args(class_loader_h);
@@ -1512,8 +1546,9 @@
   }
   k->eager_initialize(THREAD);
 
+  // (tw) Only notify jvmti if not redefining a class.
   // notify jvmti
-  if (JvmtiExport::should_post_class_load()) {
+  if (JvmtiExport::should_post_class_load() && old_class.is_null()) {
       assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
       JvmtiExport::post_class_load((JavaThread *) THREAD, k());
 
@@ -1586,7 +1621,7 @@
     }
   }
 
-  define_instance_class(k, THREAD);
+  define_instance_class(k, KlassHandle(), THREAD);
 
   Handle linkage_exception = Handle(); // null handle
 
@@ -1716,6 +1751,14 @@
   Universe::flush_dependents_on(k);
 }
 
+// (tw) Remove from hierarchy - Undo add_to_hierarchy.
+void SystemDictionary::remove_from_hierarchy(instanceKlassHandle k) {
+  assert(k.not_null(), "just checking");
+
+  k->remove_from_sibling_list();
+
+  // TODO: Remove from interfaces.
+}
 
 // ----------------------------------------------------------------------------
 // GC support
@@ -1804,7 +1847,8 @@
 }
 
 
-void SystemDictionary::preloaded_oops_do(OopClosure* f) {
+// (tw) Iterate over all pre-loaded classes in the dictionary.
+void SystemDictionary::preloaded_classes_do(OopClosure *f) {
   for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) {
     f->do_oop((oop*) &_well_known_klasses[k]);
   }
@@ -1818,6 +1862,23 @@
     }
   }
 
+  // TODO: Check if we need to call FilterFieldsMap
+}
+
+void SystemDictionary::preloaded_oops_do(OopClosure* f) {
+  for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) {
+    f->do_oop((oop*) &_well_known_klasses[k]);
+  }
+
+  {
+    for (int i = 0; i < T_VOID+1; i++) {
+      if (_box_klasses[i] != NULL) {
+        assert(i >= T_BOOLEAN, "checking");
+        f->do_oop((oop*) &_box_klasses[i]);
+      }
+    }
+  }
+
   // The basic type mirrors would have already been processed in
   // Universe::oops_do(), via a call to shared_oops_do(), so should
   // not be processed again.
@@ -1836,6 +1897,11 @@
   dictionary()->classes_do(f);
 }
 
+// (tw) Iterate over all classes in the dictionary.
+void SystemDictionary::classes_do(ObjectClosure *closure) {
+  dictionary()->classes_do(closure);
+}
+
 // Added for initialize_itable_for_klass
 //   Just the classes from defining class loaders
 // Don't iterate over placeholders
@@ -1989,7 +2055,9 @@
 
   // Preload ref klasses and set reference types
   instanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
-  instanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
+
+  // (tw) This is now done in parseClassFile in order to support class redefinition
+  // instanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
 
   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
   instanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
@@ -2081,7 +2149,11 @@
       // also holds array classes
 
       assert(check->klass_part()->oop_is_instance(), "noninstance in systemdictionary");
-      if ((defining == true) || (k() != check)) {
+      if ((defining == true) && ((k() != check) && k->old_version() != check)) {
+        ResourceMark rm(Thread::current());
+        tty->print_cr("(%d / %d) (%s/%s)", k->revision_number(), check->klass_part()->revision_number(), k->name()->as_C_string(), check->klass_part()->name()->as_C_string());
+        k()->print();
+        check->print();
         linkage_error = "loader (instance of  %s): attempted  duplicate class "
           "definition for name: \"%s\"";
       } else {
diff --git a/src/share/vm/classfile/systemDictionary.hpp b/src/share/vm/classfile/systemDictionary.hpp
--- a/src/share/vm/classfile/systemDictionary.hpp
+++ b/src/share/vm/classfile/systemDictionary.hpp
@@ -276,7 +276,7 @@
   // Resolve from stream (called by jni_DefineClass and JVM_DefineClass)
   static klassOop resolve_from_stream(Symbol* class_name, Handle class_loader,
                                       Handle protection_domain,
-                                      ClassFileStream* st, bool verify, TRAPS);
+                                      ClassFileStream* st, bool verify, KlassHandle old_class, TRAPS);
 
   // Lookup an already loaded class. If not found NULL is returned.
   static klassOop find(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS);
@@ -320,6 +320,8 @@
   // Iterate over all klasses in dictionary
   //   Just the classes from defining class loaders
   static void classes_do(void f(klassOop));
+  static void classes_do(ObjectClosure *closure);
+  static void preloaded_classes_do(OopClosure *closure);
   // Added for initialize_itable_for_klass to handle exceptions
   static void classes_do(void f(klassOop, TRAPS), TRAPS);
   //   All classes, and their class loaders
@@ -427,6 +429,8 @@
     initialize_wk_klasses_until((WKID) limit, start_id, THREAD);
   }
 
+  static void rollback_redefinition();
+
 public:
   #define WK_KLASS_DECLARE(name, symbol, option) \
     static klassOop name() { return check_klass_##option(_well_known_klasses[WK_KLASS_ENUM_NAME(name)]); }
@@ -608,7 +612,7 @@
   // after waiting, but before reentering SystemDictionary_lock
   // to preserve lock order semantics.
   static void double_lock_wait(Handle lockObject, TRAPS);
-  static void define_instance_class(instanceKlassHandle k, TRAPS);
+  static void define_instance_class(instanceKlassHandle k, KlassHandle old_class, TRAPS);
   static instanceKlassHandle find_or_define_instance_class(Symbol* class_name,
                                                 Handle class_loader,
                                                 instanceKlassHandle k, TRAPS);
@@ -627,6 +631,11 @@
   // Setup link to hierarchy
   static void add_to_hierarchy(instanceKlassHandle k, TRAPS);
 
+public:
+
+  // Remove link to hierarchy
+  static void remove_from_hierarchy(instanceKlassHandle k);
+
 private:
   // We pass in the hashtable index so we can calculate it outside of
   // the SystemDictionary_lock.
diff --git a/src/share/vm/classfile/verifier.cpp b/src/share/vm/classfile/verifier.cpp
--- a/src/share/vm/classfile/verifier.cpp
+++ b/src/share/vm/classfile/verifier.cpp
@@ -103,7 +103,7 @@
   return !need_verify;
 }
 
-bool Verifier::verify(instanceKlassHandle klass, Verifier::Mode mode, bool should_verify_class, TRAPS) {
+bool Verifier::verify(instanceKlassHandle klass, Verifier::Mode mode, bool should_verify_class, bool may_use_old_verifier, TRAPS) {
   HandleMark hm;
   ResourceMark rm(THREAD);
 
@@ -127,17 +127,19 @@
         split_verifier.verify_class(THREAD);
         exception_name = split_verifier.result();
       if (klass->major_version() < NOFAILOVER_MAJOR_VERSION &&
-          FailOverToOldVerifier && !HAS_PENDING_EXCEPTION &&
+          FailOverToOldVerifier && may_use_old_verifier && !HAS_PENDING_EXCEPTION &&
           (exception_name == vmSymbols::java_lang_VerifyError() ||
            exception_name == vmSymbols::java_lang_ClassFormatError())) {
         if (TraceClassInitialization) {
           tty->print_cr(
             "Fail over class verification to old verifier for: %s", klassName);
         }
+        assert(may_use_old_verifier, "");
         exception_name = inference_verify(
           klass, message_buffer, message_buffer_len, THREAD);
       }
     } else {
+      assert(may_use_old_verifier, "");
       exception_name = inference_verify(
           klass, message_buffer, message_buffer_len, THREAD);
     }
@@ -152,6 +154,9 @@
       }
       tty->print_cr("End class verification for: %s", klassName);
     }
+  } else if (TraceClassInitialization) {
+    // (tw) Output not verified classes
+    tty->print_cr("Class %s was not verified", klassName);
   }
 
   if (HAS_PENDING_EXCEPTION) {
@@ -203,7 +208,7 @@
     // NOTE: this is called too early in the bootstrapping process to be
     // guarded by Universe::is_gte_jdk14x_version()/UseNewReflection.
     (refl_magic_klass == NULL ||
-     !klass->is_subtype_of(refl_magic_klass) ||
+     !(klass->is_subtype_of(refl_magic_klass) || klass->is_subtype_of(refl_magic_klass->klass_part()->newest_version())) ||
      VerifyReflectionBytecodes)
   );
 }
@@ -272,7 +277,7 @@
 ClassVerifier::ClassVerifier(
     instanceKlassHandle klass, char* msg, size_t msg_len, TRAPS)
     : _thread(THREAD), _exception_type(NULL), _message(msg),
-      _message_buffer_len(msg_len), _klass(klass) {
+      _message_buffer_len(msg_len), _klass(klass->newest_version()), _klass_to_verify(klass) {
   _this_type = VerificationType::reference_type(klass->name());
   // Create list to hold symbols in reference area.
   _symbols = new GrowableArray<Symbol*>(100, 0, NULL);
@@ -296,7 +301,7 @@
       _klass->external_name());
   }
 
-  objArrayHandle methods(THREAD, _klass->methods());
+  objArrayHandle methods(THREAD, _klass_to_verify->methods());
   int num_methods = methods->length();
 
   for (int index = 0; index < num_methods; index++) {
@@ -2081,7 +2086,10 @@
         VerificationType stack_object_type =
           current_frame->pop_stack(ref_class_type, CHECK_VERIFY(this));
         if (current_type() != stack_object_type) {
-          assert(cp->cache() == NULL, "not rewritten yet");
+          
+          // (tw) TODO: Check if relaxing the following assertion is correct. For class redefinition we might call the verifier twice.
+          //assert(cp->cache() == NULL, "not rewritten yet");
+
           Symbol* ref_class_name =
             cp->klass_name_at(cp->klass_ref_index_at(index));
           // See the comments in verify_field_instructions() for
diff --git a/src/share/vm/classfile/verifier.hpp b/src/share/vm/classfile/verifier.hpp
--- a/src/share/vm/classfile/verifier.hpp
+++ b/src/share/vm/classfile/verifier.hpp
@@ -47,7 +47,7 @@
    * Otherwise, no exception is thrown and the return indicates the
    * error.
    */
-  static bool verify(instanceKlassHandle klass, Mode mode, bool should_verify_class, TRAPS);
+  static bool verify(instanceKlassHandle klass, Mode mode, bool should_verify_class, bool may_use_old_verifier, TRAPS);
 
   // Return false if the class is loaded by the bootstrap loader,
   // or if defineClass was called requesting skipping verification
@@ -97,7 +97,10 @@
   size_t _message_buffer_len;
   GrowableArray<Symbol*>* _symbols;  // keep a list of symbols created
 
+public:
   void verify_method(methodHandle method, TRAPS);
+
+private:
   char* generate_code_data(methodHandle m, u4 code_length, TRAPS);
   void verify_exception_handler_table(u4 code_length, char* code_data, int& min, int& max, TRAPS);
   void verify_local_variable_table(u4 code_length, char* code_data, TRAPS);
@@ -168,6 +171,7 @@
 
   VerificationType object_type() const;
 
+  instanceKlassHandle _klass_to_verify;
   instanceKlassHandle _klass;  // the class being verified
   methodHandle        _method; // current method being verified
   VerificationType    _this_type; // the verification type of the current class
diff --git a/src/share/vm/classfile/vmSymbols.hpp b/src/share/vm/classfile/vmSymbols.hpp
--- a/src/share/vm/classfile/vmSymbols.hpp
+++ b/src/share/vm/classfile/vmSymbols.hpp
@@ -131,6 +131,10 @@
   template(tag_annotation_default,                    "AnnotationDefault")                        \
   template(tag_enclosing_method,                      "EnclosingMethod")                          \
   template(tag_bootstrap_methods,                     "BootstrapMethods")                         \
+  template(tag_static_field_redefinition_policy,      "StaticFieldRedefinitionPolicy")            \
+  template(tag_field_redefinition_policy,             "FieldRedefinitionPolicy")                  \
+  template(tag_method_redefinition_policy,            "MethodRedefinitionPolicy")                 \
+  template(tag_code_sections,                         "CodeSections")                             \
                                                                                                   \
   /* exception klasses: at least all exceptions thrown by the VM have entries here */             \
   template(java_lang_ArithmeticException,             "java/lang/ArithmeticException")            \
@@ -376,6 +380,10 @@
   template(oop_size_name,                             "oop_size")                                 \
   template(static_oop_field_count_name,               "static_oop_field_count")                   \
                                                                                                   \
+  /* mutator in case of class redefinition */                                                     \
+  template(static_transformer_name,                   "$staticTransformer")                       \
+  template(transformer_name,                          "$transformer")                             \
+                                                                                                  \
   /* non-intrinsic name/signature pairs: */                                                       \
   template(register_method_name,                      "register")                                 \
   do_alias(register_method_signature,         object_void_signature)                              \
diff --git a/src/share/vm/compiler/compileBroker.cpp b/src/share/vm/compiler/compileBroker.cpp
--- a/src/share/vm/compiler/compileBroker.cpp
+++ b/src/share/vm/compiler/compileBroker.cpp
@@ -1166,6 +1166,14 @@
                                        int comp_level,
                                        methodHandle hot_method, int hot_count,
                                        const char* comment, Thread* THREAD) {
+  JavaThread* thread = JavaThread::current();
+  if (thread->is_Compiler_thread() && thread->as_CompilerThread()->should_bailout()) {
+    return NULL; // FIXME: DCEVM: should we do something else?
+  }
+  if (instanceKlass::cast(method->method_holder())->is_not_initialized()) {
+    return NULL; // FIXME: DCEVM: how should we avoid this?
+  }
+
   // make sure arguments make sense
   assert(method->method_holder()->klass_part()->oop_is_instance(), "not an instance method");
   assert(osr_bci == InvocationEntryBci || (0 <= osr_bci && osr_bci < method->code_size()), "bci out of range");
@@ -1245,6 +1253,7 @@
   }
 
   // RedefineClasses() has replaced this method; just return
+  // (tw) This is important for the new version of hotswapping: Old code will only execute properly in the interpreter!
   if (method->is_old()) {
     return NULL;
   }
@@ -1576,6 +1585,8 @@
 
       // Never compile a method if breakpoints are present in it
       if (method()->number_of_breakpoints() == 0) {
+        thread->compilation_mutex()->lock();
+        thread->set_should_bailout(false);
         // Compile the method.
         if ((UseCompiler || AlwaysCompileLoopMethods) && CompileBroker::should_compile_new_jobs()) {
 #ifdef COMPILER1
@@ -1599,6 +1610,7 @@
           // After compilation is disabled, remove remaining methods from queue
           method->clear_queued_for_compilation();
         }
+        thread->compilation_mutex()->unlock();
       }
     }
   }
@@ -2127,3 +2139,15 @@
   st->cr();
 #endif
 }
+
+// (tw) Clean up compiler interface after a class redefinition step
+void CompileBroker::cleanup_after_redefinition() {
+  int num_threads = _method_threads->length();
+
+  ciObjectFactory::sort_ci_objects(ciObjectFactory::_shared_ci_objects);
+  for (int i=0; i<num_threads; i++) {
+    if (_method_threads->at(i)->env() != NULL && _method_threads->at(i)->env() != (ciEnv *)badAddress) {
+      _method_threads->at(i)->env()->cleanup_after_redefinition();
+    }
+  }
+}
diff --git a/src/share/vm/compiler/compileBroker.hpp b/src/share/vm/compiler/compileBroker.hpp
--- a/src/share/vm/compiler/compileBroker.hpp
+++ b/src/share/vm/compiler/compileBroker.hpp
@@ -407,6 +407,8 @@
   static void print_last_compile();
 
   static void print_compiler_threads_on(outputStream* st);
+
+  static void cleanup_after_redefinition();
 };
 
 #endif // SHARE_VM_COMPILER_COMPILEBROKER_HPP
diff --git a/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp b/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp
--- a/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp
+++ b/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp
@@ -157,6 +157,13 @@
   }
 }
 
+
+HeapWord* CompactibleFreeListSpace::forward_compact_top(size_t size,
+                                    CompactPoint* cp, HeapWord* compact_top) {
+  ShouldNotReachHere();
+  return NULL;
+}
+
 // Like CompactibleSpace forward() but always calls cross_threshold() to
 // update the block offset table.  Removed initialize_threshold call because
 // CFLS does not use a block offset array for contiguous spaces.
diff --git a/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp b/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp
--- a/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp
+++ b/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp
@@ -149,6 +149,7 @@
 
   // Support for compacting cms
   HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
+  HeapWord* forward_compact_top(size_t size, CompactPoint* cp, HeapWord* compact_top);
   HeapWord* forward(oop q, size_t size, CompactPoint* cp, HeapWord* compact_top);
 
   // Initialization helpers.
diff --git a/src/share/vm/gc_implementation/shared/markSweep.cpp b/src/share/vm/gc_implementation/shared/markSweep.cpp
--- a/src/share/vm/gc_implementation/shared/markSweep.cpp
+++ b/src/share/vm/gc_implementation/shared/markSweep.cpp
@@ -30,6 +30,8 @@
 #include "oops/objArrayKlass.inline.hpp"
 #include "oops/oop.inline.hpp"
 
+GrowableArray<oop>*     MarkSweep::_rescued_oops       = NULL;
+
 Stack<oop>              MarkSweep::_marking_stack;
 Stack<DataLayout*>      MarkSweep::_revisit_mdo_stack;
 Stack<Klass*>           MarkSweep::_revisit_klass_stack;
@@ -350,3 +352,86 @@
 }
 
 #endif
+
+// (tw) Copy the rescued objects to their destination address after compaction.
+void MarkSweep::copy_rescued_objects_back() {
+
+  if (_rescued_oops != NULL) {
+
+    for (int i=0; i<_rescued_oops->length(); i++) {
+      oop rescued_obj = _rescued_oops->at(i);
+
+      int size = rescued_obj->size();
+      oop new_obj = rescued_obj->forwardee();
+
+      if (rescued_obj->blueprint()->new_version() != NULL) {
+        MarkSweep::update_fields(rescued_obj, new_obj);
+      } else {
+        Copy::aligned_disjoint_words((HeapWord*)rescued_obj, (HeapWord*)new_obj, size);
+      }
+
+      FREE_RESOURCE_ARRAY(HeapWord, rescued_obj, size);
+
+      new_obj->init_mark();
+      assert(new_obj->is_oop(), "must be a valid oop");
+    }
+    _rescued_oops->clear();
+    _rescued_oops = NULL;
+  }
+}
+
+// (tw) Update instances of a class whose fields changed.
+void MarkSweep::update_fields(oop q, oop new_location) {
+
+  assert(q->blueprint()->new_version() != NULL, "class of old object must have new version");
+
+  klassOop old_klass_oop = q->klass();
+  klassOop new_klass_oop = q->blueprint()->new_version();
+
+  instanceKlass *old_klass = instanceKlass::cast(old_klass_oop);
+  instanceKlass *new_klass = instanceKlass::cast(new_klass_oop);
+
+  int size = q->size_given_klass(old_klass);
+  int new_size = q->size_given_klass(new_klass);
+  
+  oop tmp_obj = q;
+
+  if (new_klass_oop->klass_part()->is_copying_backwards()) {
+    if (((HeapWord *)q >= (HeapWord *)new_location && (HeapWord *)q < (HeapWord *)new_location + new_size) || 
+        ((HeapWord *)new_location >= (HeapWord *)q && (HeapWord *)new_location < (HeapWord *)q + size)) {
+       tmp_obj = (oop)resource_allocate_bytes(size * HeapWordSize);
+       Copy::aligned_disjoint_words((HeapWord*)q, (HeapWord*)tmp_obj, size);
+    }
+  }
+  
+  int *cur = new_klass_oop->klass_part()->update_information();
+
+  tmp_obj->set_klass_no_check(new_klass_oop);
+
+  if (cur == NULL) {
+    assert(size == new_size, "just checking");
+    Copy::conjoint_words(((HeapWord *)tmp_obj), ((HeapWord *)new_location), size);
+  } else {
+    int destOffset = 0;
+    while (*cur != 0) {
+      if (*cur > 0) {
+        int size = *cur;
+        cur++;
+        int offset = *cur;
+        Copy::conjoint_jbytes(((char *)tmp_obj) + offset, ((char *)new_location) + destOffset, size);
+        destOffset += size;
+        cur++;
+      } else {
+        assert(*cur < 0, "");
+        int skip = -*cur;
+        Copy::fill_to_bytes(((char*)new_location) + destOffset, skip, 0);
+        destOffset += skip;
+        cur++;
+      }
+    }
+  }
+
+  if (tmp_obj != q) {
+    FREE_RESOURCE_ARRAY(HeapWord, tmp_obj, size);
+  }
+}
diff --git a/src/share/vm/gc_implementation/shared/markSweep.hpp b/src/share/vm/gc_implementation/shared/markSweep.hpp
--- a/src/share/vm/gc_implementation/shared/markSweep.hpp
+++ b/src/share/vm/gc_implementation/shared/markSweep.hpp
@@ -115,8 +115,12 @@
   friend class AdjustPointerClosure;
   friend class KeepAliveClosure;
   friend class VM_MarkSweep;
+  friend class GenMarkSweep;
   friend void marksweep_init();
 
+public:
+  static GrowableArray<oop>*             _rescued_oops;
+
   //
   // Vars
   //
@@ -200,6 +204,8 @@
   template <class T> static inline void mark_and_push(T* p);
   static inline void push_objarray(oop obj, size_t index);
 
+  static void copy_rescued_objects_back();
+  static void update_fields(oop q, oop new_location);
   static void follow_stack();   // Empty marking stack.
 
   static void preserve_mark(oop p, markOop mark);
diff --git a/src/share/vm/interpreter/interpreterRuntime.cpp b/src/share/vm/interpreter/interpreterRuntime.cpp
--- a/src/share/vm/interpreter/interpreterRuntime.cpp
+++ b/src/share/vm/interpreter/interpreterRuntime.cpp
@@ -403,7 +403,7 @@
     assert(h_exception.not_null(), "NULL exceptions should be handled by athrow");
     assert(h_exception->is_oop(), "just checking");
     // Check that exception is a subclass of Throwable, otherwise we have a VerifyError
-    if (!(h_exception->is_a(SystemDictionary::Throwable_klass()))) {
+    if (!(h_exception->is_a(SystemDictionary::Throwable_klass()->klass_part()->newest_version())) && !(h_exception->is_a(SystemDictionary::Throwable_klass()))) {
       if (ExitVMOnVerifyError) vm_exit(-1);
       ShouldNotReachHere();
     }
@@ -674,6 +674,82 @@
   JvmtiExport::post_raw_breakpoint(thread, method, bcp);
 IRT_END
 
+// (tw) Correctly resolve method when running old code.
+IRT_ENTRY(void, InterpreterRuntime::forward_method(JavaThread *thread))
+  {
+    MonitorLockerEx ml(RedefinitionSync_lock);
+    while (Threads::wait_at_instrumentation_entry()) {
+      ml.wait();
+    }
+  }
+  frame f = last_frame(thread);
+  methodOop m = f.interpreter_frame_method();
+  methodOop forward_method = m->forward_method();
+  if (forward_method != NULL) {
+    int bci = f.interpreter_frame_bci();
+    
+    if (TraceRedefineClasses >= 3) {
+      tty->print_cr("Executing NOP in method %s at bci %d %d", m->name()->as_C_string(), bci, m->is_in_code_section(bci + 1));
+    }
+
+    int next_bci = bci - 1;
+    // First try bci before NOP.
+    if (!m->is_in_code_section(next_bci)) {
+      // Try bci after NOP.
+      next_bci = bci + 1;
+      if (!m->is_in_code_section(next_bci)) return;
+    }
+    
+    int new_bci = m->calculate_forward_bci(next_bci, forward_method);
+    if (TraceRedefineClasses >= 2) {
+      tty->print_cr("Transfering execution of %s to new method old_bci=%d new_bci=%d", forward_method->name()->as_C_string(), bci, new_bci);
+    }
+    RegisterMap reg_map(thread);
+    vframe* vf = vframe::new_vframe(&f, &reg_map, thread);
+    interpretedVFrame *iframe = (interpretedVFrame *)vf;
+    iframe->set_method(forward_method, new_bci - 1);
+  }
+IRT_END
+
+// (tw) Correctly resolve method when running old code.
+IRT_ENTRY(void, InterpreterRuntime::find_correct_method(JavaThread *thread, oopDesc* receiverOop, int vTableIndex))
+  // extract receiver from the outgoing argument list if necessary
+  Handle receiver(thread, receiverOop);
+
+  // TODO: Check for invokeinterface!
+  Bytecodes::Code bytecode = Bytecodes::_invokevirtual;
+
+  int method_holder_revision_number = method(thread)->method_holder()->klass_part()->revision_number();
+  klassOop klass = receiverOop->klass();
+  while (klass->klass_part()->revision_number() > method_holder_revision_number) {
+    klass = klass->klass_part()->old_version();
+  }
+
+  // TODO: Check for correctness if different vtable indices in different versions?
+
+  methodOop method = ((instanceKlass *)klass->klass_part())->method_at_vtable(vTableIndex);
+  thread->set_vm_result(method);
+IRT_END
+
+// Correctly resolve interface method when running old code.
+IRT_ENTRY(void, InterpreterRuntime::find_correct_interface_method(JavaThread *thread, oopDesc* receiverOop, oopDesc* interface_klass, int vTableIndex))
+
+  // extract receiver from the outgoing argument list if necessary
+  Handle receiver(thread, receiverOop);
+
+  // TODO: Check for invokeinterface!
+  Bytecodes::Code bytecode = Bytecodes::_invokevirtual;
+
+  int method_holder_revision_number = method(thread)->method_holder()->klass_part()->revision_number();
+  klassOop klass = receiverOop->klass();
+  while (klass->klass_part()->revision_number() > method_holder_revision_number) {
+    klass = klass->klass_part()->old_version();
+  }
+
+  methodOop method = ((instanceKlass *)klass->klass_part())->method_at_itable((klassOop)interface_klass, vTableIndex, THREAD);
+  thread->set_vm_result(method);
+IRT_END
+
 IRT_ENTRY(void, InterpreterRuntime::resolve_invoke(JavaThread* thread, Bytecodes::Code bytecode))
   // extract receiver from the outgoing argument list if necessary
   Handle receiver(thread, NULL);
@@ -702,6 +778,10 @@
     if (JvmtiExport::can_hotswap_or_post_breakpoint()) {
       int retry_count = 0;
       while (info.resolved_method()->is_old()) {
+        // (tw) If we are executing an old method, this is OK!
+        if (method(thread)->is_old()) {
+          break;
+        }
         // It is very unlikely that method is redefined more than 100 times
         // in the middle of resolve. If it is looping here more than 100 times
         // means then there could be a bug here.
diff --git a/src/share/vm/interpreter/interpreterRuntime.hpp b/src/share/vm/interpreter/interpreterRuntime.hpp
--- a/src/share/vm/interpreter/interpreterRuntime.hpp
+++ b/src/share/vm/interpreter/interpreterRuntime.hpp
@@ -137,6 +137,9 @@
   static void post_method_entry(JavaThread *thread);
   static void post_method_exit (JavaThread *thread);
   static int  interpreter_contains(address pc);
+  static void forward_method(JavaThread *thread);
+  static void find_correct_method(JavaThread *thread, oopDesc* receiver, int vTableIndex);
+  static void find_correct_interface_method(JavaThread *thread, oopDesc* receiver, oopDesc* interface_klass, int vTableIndex);
 
   // Native signature handlers
   static void prepare_native_call(JavaThread* thread, methodOopDesc* method);
diff --git a/src/share/vm/interpreter/linkResolver.cpp b/src/share/vm/interpreter/linkResolver.cpp
--- a/src/share/vm/interpreter/linkResolver.cpp
+++ b/src/share/vm/interpreter/linkResolver.cpp
@@ -145,8 +145,8 @@
 // Klass resolution
 
 void LinkResolver::check_klass_accessability(KlassHandle ref_klass, KlassHandle sel_klass, TRAPS) {
-  if (!Reflection::verify_class_access(ref_klass->as_klassOop(),
-                                       sel_klass->as_klassOop(),
+  if (!Reflection::verify_class_access(ref_klass->as_klassOop()->klass_part()->newest_version(),
+                                       sel_klass->as_klassOop()->klass_part()->newest_version(),
                                        true)) {
     ResourceMark rm(THREAD);
     Exceptions::fthrow(
@@ -258,7 +258,7 @@
   // We'll check for the method name first, as that's most likely
   // to be false (so we'll short-circuit out of these tests).
   if (sel_method->name() == vmSymbols::clone_name() &&
-      sel_klass() == SystemDictionary::Object_klass() &&
+      sel_klass()->klass_part()->newest_version() == SystemDictionary::Object_klass()->klass_part()->newest_version() &&
       resolved_klass->oop_is_array()) {
     // We need to change "protected" to "public".
     assert(flags.is_protected(), "clone not protected?");
@@ -334,6 +334,149 @@
 }
 
 
+void LinkResolver::lookup_method(methodHandle& resolved_method, KlassHandle resolved_klass,
+                   Symbol* method_name, Symbol* method_signature, bool is_interface, KlassHandle current_klass, TRAPS) {
+
+   // Interface method lookup?
+   if (is_interface) {
+
+     // lookup method in this interface or its super, java.lang.Object
+     lookup_instance_method_in_klasses(resolved_method, resolved_klass, method_name, method_signature, CHECK);
+
+     if (resolved_method.is_null()) {
+       // lookup method in all the super-interfaces
+       lookup_method_in_interfaces(resolved_method, resolved_klass, method_name, method_signature, CHECK);
+     }
+
+   // Other methods
+   } else {
+
+    // 2. lookup method in resolved klass and its super klasses
+    lookup_method_in_klasses(resolved_method, resolved_klass, method_name, method_signature, CHECK);
+
+    if (resolved_method.is_null()) { // not found in the class hierarchy
+      // 3. lookup method in all the interfaces implemented by the resolved klass
+      lookup_method_in_interfaces(resolved_method, resolved_klass, method_name, method_signature, CHECK);
+
+      if (resolved_method.is_null()) {
+        // JSR 292:  see if this is an implicitly generated method MethodHandle.invoke(*...)
+        lookup_implicit_method(resolved_method, resolved_klass, method_name, method_signature, current_klass, CHECK);
+      }
+    }
+  }
+}
+
+void LinkResolver::lookup_correct_field(fieldDescriptor &fd, KlassHandle &sel_klass, KlassHandle resolved_klass, KlassHandle current_klass, Symbol* field_name, Symbol* field_sig, bool is_static) {
+
+  // First attempt unversioned
+  sel_klass = KlassHandle(Thread::current(), instanceKlass::cast(resolved_klass())->find_field(field_name, field_sig, &fd));
+
+
+  if (!current_klass.is_null() && !current_klass->is_newest_version()) {
+
+    // Look for the policy defined in the new version of the class (_not_ in the newest, but only in the newer relative to current klass).
+    int redefinition_policy = current_klass->new_version()->klass_part()->field_redefinition_policy();
+    if (is_static) {
+      redefinition_policy = current_klass->new_version()->klass_part()->static_field_redefinition_policy();
+    }
+
+    assert(redefinition_policy != Klass::StaticCheck, "if the policy is static check, then we can never reach here");
+
+    if (redefinition_policy != Klass::DynamicCheck) {
+
+      if (redefinition_policy == Klass::AccessOldMembers) {
+        // Forget looked up fields
+        sel_klass = KlassHandle(Thread::current(), (oop)NULL);
+      }
+
+      assert(redefinition_policy == Klass::AccessOldMembers || redefinition_policy == Klass::AccessDeletedMembers, "");
+
+      if (sel_klass.is_null() || fd.is_static() != is_static /* access old static field field is changed from static to non-static */) {
+
+        // Select correct version for resolved klass.
+        find_correct_resolved_klass(resolved_klass, current_klass);
+
+        sel_klass = KlassHandle(Thread::current(), instanceKlass::cast(resolved_klass())->find_field(field_name, field_sig, &fd));
+
+        // FIXME: idubrov
+        //if (sel_klass.is_null()) {
+        //  TRACE_RC2("Trying to resolve field (%s) in old universe failed => exception is the correct behaviour", field_name->as_C_string());
+        //} else {
+        //  assert(sel_klass->new_version() != NULL, "must be old class!");
+        //  TRACE_RC2("Resolved a field in the old universe (%s)!", field_name->as_C_string());
+        //}
+      }
+    }
+  }
+}
+
+void LinkResolver::lookup_correct_method(methodHandle& resolved_method, KlassHandle resolved_klass, KlassHandle current_klass,
+                                 Symbol* method_name, Symbol* method_signature, bool is_interface, TRAPS) {
+
+   // First attempt unversioned
+   lookup_method(resolved_method, resolved_klass, method_name, method_signature, is_interface, current_klass, CHECK);
+
+   // (tw) Are we in an old method that wants to see a different view on the world?
+   if (!current_klass.is_null() && !current_klass->is_newest_version()) {
+
+     // Look for the policy defined in the new version of the class (_not_ in the newest, but only in the newer relative to current klass).
+     int method_redefinition_policy = current_klass->new_version()->klass_part()->method_redefinition_policy();
+     assert(method_redefinition_policy != Klass::StaticCheck, "if the policy is static check, then we can never reach here");
+
+     if (method_redefinition_policy != Klass::DynamicCheck) {
+
+       // We do not throw the exception
+       if (method_redefinition_policy == Klass::AccessOldMembers) {
+         // Forget any new member lookup
+         resolved_method = methodHandle(THREAD, NULL);
+       }
+
+       assert(method_redefinition_policy == Klass::AccessOldMembers || method_redefinition_policy == Klass::AccessDeletedMembers, "");
+
+       if (resolved_method.is_null()) {
+
+         // Select correct version for resolved klass.
+         find_correct_resolved_klass(resolved_klass, current_klass);
+
+         // Now do the lookup in a second attempt with a different resolved klass.
+         lookup_method(resolved_method, resolved_klass, method_name, method_signature, is_interface, current_klass, CHECK);
+
+         // FIXME: idubrov
+         //IF_TRACE_RC2 {
+         //  ResourceMark rm(THREAD);
+         //  if (resolved_method.is_null()) {
+         //    TRACE_RC2("Trying to resolve method (%s) in old universe failed => exception is the correct behaviour", method_name->as_C_string());
+         //  } else {
+         //    assert(resolved_method->is_old(), "must be old method!");
+         //    TRACE_RC2("Resolved a method in the old universe (%s)!", resolved_method->name()->as_C_string());
+         //  }
+         //}
+       }
+     }
+   }
+
+   if (resolved_method.is_null()) {
+     // no method found
+     ResourceMark rm(THREAD);
+     THROW_MSG(vmSymbols::java_lang_NoSuchMethodError(),
+       methodOopDesc::name_and_sig_as_C_string(Klass::cast(resolved_klass()),
+       method_name,
+       method_signature));
+   }
+}
+
+void LinkResolver::find_correct_resolved_klass(KlassHandle &resolved_klass, KlassHandle &current_klass) {
+  int current_klass_revision = current_klass->revision_number();
+  int resolved_klass_revision = resolved_klass->revision_number();
+  // FIXME: idubrov
+  //TRACE_RC2("The two different revision numbers for interfaces: current=%d / resolved_callee=%d", current_klass_revision, resolved_klass_revision);
+
+  while (resolved_klass->revision_number() > current_klass_revision) {
+    assert(resolved_klass->old_version(), "must have old version");
+	resolved_klass = KlassHandle(Thread::current(), resolved_klass->old_version());
+  }
+}
+
 void LinkResolver::resolve_method(methodHandle& resolved_method, KlassHandle resolved_klass,
                                   Symbol* method_name, Symbol* method_signature,
                                   KlassHandle current_klass, bool check_access, TRAPS) {
@@ -346,27 +489,8 @@
     THROW_MSG(vmSymbols::java_lang_IncompatibleClassChangeError(), buf);
   }
 
-  // 2. lookup method in resolved klass and its super klasses
-  lookup_method_in_klasses(resolved_method, resolved_klass, method_name, method_signature, CHECK);
-
-  if (resolved_method.is_null()) { // not found in the class hierarchy
-    // 3. lookup method in all the interfaces implemented by the resolved klass
-    lookup_method_in_interfaces(resolved_method, resolved_klass, method_name, method_signature, CHECK);
-
-    if (resolved_method.is_null()) {
-      // JSR 292:  see if this is an implicitly generated method MethodHandle.invoke(*...)
-      lookup_implicit_method(resolved_method, resolved_klass, method_name, method_signature, current_klass, CHECK);
-    }
-
-    if (resolved_method.is_null()) {
-      // 4. method lookup failed
-      ResourceMark rm(THREAD);
-      THROW_MSG(vmSymbols::java_lang_NoSuchMethodError(),
-                methodOopDesc::name_and_sig_as_C_string(Klass::cast(resolved_klass()),
-                                                        method_name,
-                                                        method_signature));
-    }
-  }
+  // 2. and 3. and 4. lookup method in resolved klass and its super klasses
+  lookup_correct_method(resolved_method, resolved_klass, current_klass, method_name, method_signature, false, CHECK);
 
   // 5. check if method is concrete
   if (resolved_method->is_abstract() && !resolved_klass->is_abstract()) {
@@ -434,20 +558,7 @@
   }
 
   // lookup method in this interface or its super, java.lang.Object
-  lookup_instance_method_in_klasses(resolved_method, resolved_klass, method_name, method_signature, CHECK);
-
-  if (resolved_method.is_null()) {
-    // lookup method in all the super-interfaces
-    lookup_method_in_interfaces(resolved_method, resolved_klass, method_name, method_signature, CHECK);
-    if (resolved_method.is_null()) {
-      // no method found
-      ResourceMark rm(THREAD);
-      THROW_MSG(vmSymbols::java_lang_NoSuchMethodError(),
-                methodOopDesc::name_and_sig_as_C_string(Klass::cast(resolved_klass()),
-                                                        method_name,
-                                                        method_signature));
-    }
-  }
+  lookup_correct_method(resolved_method, resolved_klass, current_klass, method_name, method_signature, true, CHECK);
 
   if (check_access) {
     HandleMark hm(THREAD);
@@ -534,9 +645,14 @@
     THROW_MSG(vmSymbols::java_lang_NoSuchFieldError(), field->as_C_string());
   }
 
+  KlassHandle ref_klass(THREAD, pool->pool_holder()->klass_part());
+
   // Resolve instance field
   fieldDescriptor fd; // find_field initializes fd if found
-  KlassHandle sel_klass(THREAD, instanceKlass::cast(resolved_klass())->find_field(field, sig, &fd));
+
+  KlassHandle sel_klass;
+  lookup_correct_field(fd, sel_klass, resolved_klass, ref_klass, field, sig, is_static);
+
   // check if field exists; i.e., if a klass containing the field def has been selected
   if (sel_klass.is_null()){
     ResourceMark rm(THREAD);
@@ -544,7 +660,6 @@
   }
 
   // check access
-  KlassHandle ref_klass(THREAD, pool->pool_holder());
   check_field_accessability(ref_klass, resolved_klass, sel_klass, fd, CHECK);
 
   // check for errors
@@ -556,7 +671,7 @@
   }
 
   // Final fields can only be accessed from its own class.
-  if (is_put && fd.access_flags().is_final() && sel_klass() != pool->pool_holder()) {
+  if (is_put && fd.access_flags().is_final() && sel_klass() != pool->pool_holder()->klass_part()->active_version() && sel_klass() != pool->pool_holder()) {
     THROW(vmSymbols::java_lang_IllegalAccessError());
   }
 
@@ -761,7 +876,7 @@
                                         bool check_access, bool check_null_and_abstract, TRAPS) {
   methodHandle resolved_method;
   linktime_resolve_virtual_method(resolved_method, resolved_klass, method_name, method_signature, current_klass, check_access, CHECK);
-  runtime_resolve_virtual_method(result, resolved_method, resolved_klass, recv, receiver_klass, check_null_and_abstract, CHECK);
+  runtime_resolve_virtual_method(result, resolved_method, resolved_klass, recv, receiver_klass, current_klass, check_null_and_abstract, CHECK);
 }
 
 // throws linktime exceptions
@@ -791,6 +906,7 @@
                                                   KlassHandle resolved_klass,
                                                   Handle recv,
                                                   KlassHandle recv_klass,
+                                                  KlassHandle current_klass,
                                                   bool check_null_and_abstract,
                                                   TRAPS) {
 
@@ -839,7 +955,40 @@
       // recv_klass might be an arrayKlassOop but all vtables start at
       // the same place. The cast is to avoid virtual call and assertion.
       instanceKlass* inst = (instanceKlass*)recv_klass()->klass_part();
+
+      // (tw) The type of the virtual method call and the type of the receiver do not need to 
+      // have anything in common, as the receiver type could've been hotswapped.
+      // Does not always work (method could be resolved with correct dynamic type and later
+      // be called at the same place with a wrong dynamic type).
+      // (tw) TODO: Need to handle the static type vs dynamic type issue more generally.
+
+      // The vTable must be based on the view of the world of the resolved method
+      klassOop method_holder = resolved_method->method_holder();
+
+      if (method_holder->klass_part()->new_version() != NULL) {
+        // We are executing in old code
+        // FIXME: idubrov
+        //TRACE_RC2("Calling a method in old code");
+        while (method_holder->klass_part()->revision_number() < inst->revision_number()) {
+          inst = (instanceKlass *)(inst->old_version()->klass_part());
+        }
+      }
+
+      if (inst->is_subtype_of(method_holder)) {
       selected_method = methodHandle(THREAD, inst->method_at_vtable(vtable_index));
+      } else {
+
+        tty->print_cr("Failure:");
+        inst->as_klassOop()->print();
+        inst->super()->print();
+        juint    off = inst->super_check_offset();
+        klassOop sup = *(klassOop*)( (address)inst->as_klassOop() + off );
+        sup->print();
+        method_holder->print();
+
+        bool b = inst->is_subtype_of(method_holder);
+        THROW_MSG(vmSymbols::java_lang_NoSuchMethodError(), "(tw) A virtual method was called, but the type of the receiver is not related with the type of the class of the called method!");
+      }
     }
   }
 
diff --git a/src/share/vm/interpreter/linkResolver.hpp b/src/share/vm/interpreter/linkResolver.hpp
--- a/src/share/vm/interpreter/linkResolver.hpp
+++ b/src/share/vm/interpreter/linkResolver.hpp
@@ -106,7 +106,11 @@
 // It does all necessary link-time checks & throws exceptions if necessary.
 
 class LinkResolver: AllStatic {
- private:
+private:
+  static void lookup_method                     (methodHandle& result, KlassHandle resolved_klass, Symbol* name, Symbol* signature, bool is_interface, KlassHandle current_klass, TRAPS);
+  static void lookup_correct_field				(fieldDescriptor &fd, KlassHandle &sel_klass, KlassHandle resolved_klass, KlassHandle current_klass, Symbol* field_name, Symbol* field_sig, bool is_static);
+  static void lookup_correct_method             (methodHandle& result, KlassHandle resolved_klass, KlassHandle current_klass, Symbol* name, Symbol* signature, bool is_interface, TRAPS);
+  static void find_correct_resolved_klass       (KlassHandle &resolved_klass, KlassHandle &current_klass);
   static void lookup_method_in_klasses          (methodHandle& result, KlassHandle klass, Symbol* name, Symbol* signature, TRAPS);
   static void lookup_instance_method_in_klasses (methodHandle& result, KlassHandle klass, Symbol* name, Symbol* signature, TRAPS);
   static void lookup_method_in_interfaces       (methodHandle& result, KlassHandle klass, Symbol* name, Symbol* signature, TRAPS);
@@ -129,7 +133,7 @@
   static void linktime_resolve_interface_method (methodHandle& resolved_method, KlassHandle resolved_klass, Symbol* method_name, Symbol* method_signature, KlassHandle current_klass, bool check_access, TRAPS);
 
   static void runtime_resolve_special_method    (CallInfo& result, methodHandle resolved_method, KlassHandle resolved_klass, KlassHandle current_klass, bool check_access, TRAPS);
-  static void runtime_resolve_virtual_method    (CallInfo& result, methodHandle resolved_method, KlassHandle resolved_klass, Handle recv, KlassHandle recv_klass, bool check_null_and_abstract, TRAPS);
+  static void runtime_resolve_virtual_method    (CallInfo& result, methodHandle resolved_method, KlassHandle resolved_klass, Handle recv, KlassHandle recv_klass, KlassHandle current_klass, bool check_null_and_abstract, TRAPS);
   static void runtime_resolve_interface_method  (CallInfo& result, methodHandle resolved_method, KlassHandle resolved_klass, Handle recv, KlassHandle recv_klass, bool check_null_and_abstract, TRAPS);
 
   static void check_field_accessability   (KlassHandle ref_klass, KlassHandle resolved_klass, KlassHandle sel_klass, fieldDescriptor& fd, TRAPS);
diff --git a/src/share/vm/interpreter/templateTable.hpp b/src/share/vm/interpreter/templateTable.hpp
--- a/src/share/vm/interpreter/templateTable.hpp
+++ b/src/share/vm/interpreter/templateTable.hpp
@@ -328,8 +328,8 @@
   static void shouldnotreachhere();
 
   // jvmti support
-  static void jvmti_post_field_access(Register cache, Register index, bool is_static, bool has_tos);
-  static void jvmti_post_field_mod(Register cache, Register index, bool is_static);
+  static void jvmti_post_field_access(Register cache, Register index, int byte_no, bool is_static, bool has_tos);
+  static void jvmti_post_field_mod(Register cache, Register index, int byte_no, bool is_static);
   static void jvmti_post_fast_field_mod();
 
   // debugging of TemplateGenerator
diff --git a/src/share/vm/memory/genMarkSweep.cpp b/src/share/vm/memory/genMarkSweep.cpp
--- a/src/share/vm/memory/genMarkSweep.cpp
+++ b/src/share/vm/memory/genMarkSweep.cpp
@@ -409,6 +409,7 @@
   // in the same order in phase2, phase3 and phase4. We don't quite do that
   // here (perm_gen first rather than last), so we tell the validate code
   // to use a higher index (saved from phase2) when verifying perm_gen.
+  assert(_rescued_oops == NULL, "must be empty before processing");
   GenCollectedHeap* gch = GenCollectedHeap::heap();
   Generation* pg = gch->perm_gen();
 
@@ -421,10 +422,14 @@
 
   VALIDATE_MARK_SWEEP_ONLY(reset_live_oop_tracking(false));
 
+  MarkSweep::copy_rescued_objects_back();
+
   GenCompactClosure blk;
   gch->generation_iterate(&blk, true);
 
   VALIDATE_MARK_SWEEP_ONLY(compaction_complete());
 
+  MarkSweep::copy_rescued_objects_back();
+
   pg->post_compact(); // Shared spaces verification.
 }
diff --git a/src/share/vm/memory/permGen.cpp b/src/share/vm/memory/permGen.cpp
--- a/src/share/vm/memory/permGen.cpp
+++ b/src/share/vm/memory/permGen.cpp
@@ -57,7 +57,12 @@
 
   for (;;) {
     {
-      MutexLocker ml(Heap_lock);
+      // (tw) Only lock when not at a safepoint (necessary to use the split verifier from the VmThread)
+      Monitor *lock = Heap_lock;
+      if (SafepointSynchronize::is_at_safepoint()) {
+        lock = NULL;
+      }
+      MutexLockerEx ml(lock);
       if ((obj = gen->allocate(size, false)) != NULL) {
         return obj;
       }
diff --git a/src/share/vm/memory/space.cpp b/src/share/vm/memory/space.cpp
--- a/src/share/vm/memory/space.cpp
+++ b/src/share/vm/memory/space.cpp
@@ -378,6 +378,31 @@
   _compaction_top = bottom();
 }
 
+// (tw) Calculates the compact_top that will be used for placing the next object with the giving size on the heap.
+HeapWord* CompactibleSpace::forward_compact_top(size_t size,
+CompactPoint* cp, HeapWord* compact_top) {
+  // First check if we should switch compaction space
+  assert(this == cp->space, "'this' should be current compaction space.");
+  size_t compaction_max_size = pointer_delta(end(), compact_top);
+  while (size > compaction_max_size) {
+    // switch to next compaction space
+    cp->space->set_compaction_top(compact_top);
+    cp->space = cp->space->next_compaction_space();
+    if (cp->space == NULL) {
+      cp->gen = GenCollectedHeap::heap()->prev_gen(cp->gen);
+      assert(cp->gen != NULL, "compaction must succeed");
+      cp->space = cp->gen->first_compaction_space();
+      assert(cp->space != NULL, "generation must have a first compaction space");
+    }
+    compact_top = cp->space->bottom();
+    cp->space->set_compaction_top(compact_top);
+    cp->threshold = cp->space->initialize_threshold();
+    compaction_max_size = pointer_delta(cp->space->end(), compact_top);
+  }
+
+  return compact_top;
+}
+
 HeapWord* CompactibleSpace::forward(oop q, size_t size,
                                     CompactPoint* cp, HeapWord* compact_top) {
   // q is alive
@@ -401,7 +426,7 @@
   }
 
   // store the forwarding pointer into the mark word
-  if ((HeapWord*)q != compact_top) {
+  if ((HeapWord*)q != compact_top || (size_t)q->size() != size) {
     q->forward_to(oop(compact_top));
     assert(q->is_gc_marked(), "encoding the pointer should preserve the mark");
   } else {
@@ -449,7 +474,208 @@
 
 // Faster object search.
 void ContiguousSpace::prepare_for_compaction(CompactPoint* cp) {
-  SCAN_AND_FORWARD(cp, top, block_is_always_obj, obj_size);
+  if (!Universe::is_redefining_gc_run()) {
+    SCAN_AND_FORWARD(cp, top, block_is_always_obj, obj_size);
+    return;
+  }
+
+  /* Compute the new addresses for the live objects and store it in the mark 
+   * Used by universe::mark_sweep_phase2()                                   
+   */                                                                        
+  HeapWord* compact_top; /* This is where we are currently compacting to. */ 
+                                                                             
+  /* We're sure to be here before any objects are compacted into this        
+   * space, so this is a good time to initialize this:                       
+   */                                                                        
+  set_compaction_top(bottom());                                              
+                                                                             
+  if (cp->space == NULL) {                                                   
+    assert(cp->gen != NULL, "need a generation");                            
+    assert(cp->threshold == NULL, "just checking");                          
+    assert(cp->gen->first_compaction_space() == this, "just checking");      
+    cp->space = cp->gen->first_compaction_space();                           
+    compact_top = cp->space->bottom();                                       
+    cp->space->set_compaction_top(compact_top);                              
+    cp->threshold = cp->space->initialize_threshold();                       
+  } else {                                                                  
+    compact_top = cp->space->compaction_top();                               
+  }                                                                          
+                                                                             
+  /* We allow some amount of garbage towards the bottom of the space, so     
+   * we don't start compacting before there is a significant gain to be made.
+   * Occasionally, we want to ensure a full compaction, which is determined  
+   * by the MarkSweepAlwaysCompactCount parameter.                           
+   */                                                                        
+  int invocations = SharedHeap::heap()->perm_gen()->stat_record()->invocations;
+  bool skip_dead = (MarkSweepAlwaysCompactCount < 1)
+    ||((invocations % MarkSweepAlwaysCompactCount) != 0);
+
+  size_t allowed_deadspace = 0;                                              
+  if (skip_dead) {                                                           
+    int ratio = (int)allowed_dead_ratio();                                        
+    allowed_deadspace = (capacity() * ratio / 100) / HeapWordSize;           
+  }                                                                          
+                                                                             
+  HeapWord* q = bottom();                                                    
+  HeapWord* t = end();                                                
+                                                                             
+  HeapWord*  end_of_live= q;    /* One byte beyond the last byte of the last 
+                                   live object. */                           
+  HeapWord*  first_dead = end();/* The first dead object. */                 
+  LiveRange* liveRange  = NULL; /* The current live range, recorded in the   
+                                   first header of preceding free area. */   
+  _first_dead = first_dead;                                                  
+                                                                            
+  const intx interval = PrefetchScanIntervalInBytes;                         
+                                                                             
+  while (q < t) {                                                            
+    assert(!block_is_obj(q) ||                                               
+           oop(q)->mark()->is_marked() || oop(q)->mark()->is_unlocked() ||   
+           oop(q)->mark()->has_bias_pattern(),                               
+           "these are the only valid states during a mark sweep");           
+    if (block_is_obj(q) && oop(q)->is_gc_marked()) {                         
+      /* prefetch beyond q */                                                
+      Prefetch::write(q, interval);                                          
+      /* size_t size = oop(q)->size();  changing this for cms for perm gen */
+      size_t size = block_size(q);     
+
+      // DCEVM: begin
+      //////////////////////////////////////////////////////////////////////////
+      size_t forward_size = size;
+      
+      // Compute the forward sizes and leave out objects whose position could
+      // possibly overlap other objects.
+
+      // DCEVM: There is a new version of the class of q => different size
+      if (oop(q)->blueprint()->new_version() != NULL && oop(q)->blueprint()->new_version()->klass_part()->update_information() != NULL) {
+      
+        size_t new_size = oop(q)->size_given_klass(oop(q)->blueprint()->new_version()->klass_part());
+        assert(size != new_size || oop(q)->is_perm(), "instances without changed size have to be updated prior to GC run");
+        forward_size = new_size;
+      }
+
+      compact_top = cp->space->forward_compact_top(forward_size, cp, compact_top);
+
+      bool rescueing = false;
+      if (rescueing = must_rescue(oop(q), oop(compact_top))) {
+        if (MarkSweep::_rescued_oops == NULL) {
+          MarkSweep::_rescued_oops = new GrowableArray<oop>(128);
+        }
+        // FIXME: idubrov
+        //TRACE_RC5("rescue obj %d klass=%s", MarkSweep::_rescued_oops->length(), oop(q)->klass()->klass_part()->name()->as_C_string());
+        MarkSweep::_rescued_oops->append(oop(q));
+      } else {
+        compact_top = cp->space->forward(oop(q), forward_size, cp, compact_top);
+      }
+      
+      if ((size != forward_size || rescueing) && q < first_dead) {
+        // (tw) This object moves => first_dead must be set to here!
+        first_dead = q;
+      }
+      //////////////////////////////////////////////////////////////////////////
+      q += size;                                                          
+      end_of_live = q;
+    } else {                                                                 
+      /* run over all the contiguous dead objects */                         
+      HeapWord* end = q;                                                     
+      do {                                                                   
+        /* prefetch beyond end */                                            
+        Prefetch::write(end, interval);                                      
+        end += block_size(end);                                              
+      } while (end < t && (!block_is_obj(end) || !oop(end)->is_gc_marked()));
+                                                                             
+      /* see if we might want to pretend this object is alive so that        
+       * we don't have to compact quite as often.                            
+       */                                                                    
+      if (allowed_deadspace > 0 && q == compact_top) {                       
+        size_t sz = pointer_delta(end, q);                                   
+        if (insert_deadspace(allowed_deadspace, q, sz)) {                    
+          compact_top = cp->space->forward(oop(q), sz, cp, compact_top);     
+          q = end;                                                           
+          end_of_live = end;                                                 
+          continue;                                                          
+        }                                                                    
+      }                                                                      
+                                                                             
+      /* otherwise, it really is a free region. */                           
+                                                                             
+      /* for the previous LiveRange, record the end of the live objects. */  
+      if (liveRange) {                                                       
+        liveRange->set_end(q);                                               
+      }                                                                      
+                                                                             
+      /* record the current LiveRange object.                                
+       * liveRange->start() is overlaid on the mark word.                    
+       */                                                                    
+      liveRange = (LiveRange*)q;                                             
+      liveRange->set_start(end);                                             
+      liveRange->set_end(end);                                               
+                                                                             
+      /* see if this is the first dead region. */                            
+      if (q < first_dead) {                                                  
+        first_dead = q;                                                      
+      }                                                                      
+                                                                             
+      /* move on to the next object */                                       
+      q = end;                                                               
+    }                                                                        
+  }
+
+  //////////////////////////////////////////////////////////////////////////
+  // Compute the forwarding addresses for the objects that need to be
+  // rescued.
+  // TODO: empty the _rescued_oops after ALL spaces are compacted!
+  if (MarkSweep::_rescued_oops != NULL) {
+    // FIXME: idubrov
+    //TRACE_RC2("Calculating new forward sizes for %d objects!", MarkSweep::_rescued_oops->length());
+
+    for (int i=0; i<MarkSweep::_rescued_oops->length(); i++) {
+      oop q = MarkSweep::_rescued_oops->at(i);
+
+      /* size_t size = oop(q)->size();  changing this for cms for perm gen */
+      size_t size = block_size((HeapWord*)q);     
+
+      size_t forward_size = size;
+
+      // (tw) There is a new version of the class of q => different size
+      if (oop(q)->blueprint()->new_version() != NULL) {
+
+        size_t new_size = oop(q)->size_given_klass(oop(q)->blueprint()->new_version()->klass_part());
+        assert(size != new_size || oop(q)->is_perm(), "instances without changed size have to be updated prior to GC run");
+        forward_size = new_size;
+      }
+      
+      compact_top = cp->space->forward(oop(q), forward_size, cp, compact_top);
+      assert(compact_top <= t, "must not write over end of space!");
+    }
+    MarkSweep::_rescued_oops->clear();
+    MarkSweep::_rescued_oops = NULL;
+  }
+  //////////////////////////////////////////////////////////////////////////
+                      
+  assert(q == t, "just checking");                                           
+  if (liveRange != NULL) {                                                   
+    liveRange->set_end(q);                                                   
+  }                                                                         
+  _end_of_live = end_of_live;                                                
+  if (end_of_live < first_dead) {                                            
+    first_dead = end_of_live;                                                
+  }                                                                          
+  _first_dead = first_dead;    
+
+// FIXME: idubrov
+//  if (_first_dead > top()) {
+//    _first_dead = top();
+//  }
+//
+//  if (_end_of_live > top()) {
+//    _end_of_live = top();
+//  }
+  assert(_first_dead <= top(), "Must be smaller equal");
+  assert(_end_of_live <= top(), "Must be smaller equal");
+                                                                             
+  /* save the compaction_top of the compaction space. */                     
+  cp->space->set_compaction_top(compact_top);      
 }
 
 void Space::adjust_pointers() {
@@ -490,17 +716,313 @@
   assert(q == t, "just checking");
 }
 
+
+#ifdef ASSERT
+
+int CompactibleSpace::space_index(oop obj) {
+  GenCollectedHeap* heap = GenCollectedHeap::heap();
+
+  if (heap->is_in_permanent(obj)) {
+    return -1;
+  }
+
+  int index = 0;
+  for (int i = heap->n_gens() - 1; i >= 0; i--) {
+    Generation* gen = heap->get_gen(i);
+    CompactibleSpace* space = gen->first_compaction_space();
+    while (space != NULL) {
+      if (space->is_in_reserved(obj)) {
+        return index;
+      }
+      space = space->next_compaction_space();
+      index++;
+    }
+  }
+
+  tty->print_cr("could not compute space_index for %08xh", obj);
+  index = 0;
+  for (int i = heap->n_gens() - 1; i >= 0; i--) {
+    Generation* gen = heap->get_gen(i);
+    tty->print_cr("  generation %s: %08xh - %08xh", gen->name(), gen->reserved().start(), gen->reserved().end());
+
+    CompactibleSpace* space = gen->first_compaction_space();
+    while (space != NULL) {
+      tty->print_cr("    %2d space %08xh - %08xh", index, space->bottom(), space->end());
+      space = space->next_compaction_space();
+      index++;
+    }
+  }
+
+  ShouldNotReachHere();
+  return 0;
+}
+#endif
+
+bool CompactibleSpace::must_rescue(oop old_obj, oop new_obj) {
+
+  assert(is_in_reserved(old_obj), "old_obj must be in this space");
+
+  if (old_obj->is_perm()) {
+    // This object is in perm gen; check for invariant obj->klass() <= obj
+    if (oop(old_obj)->blueprint()->new_version() != NULL) {
+      return true;
+    }
+  }
+
+  int size = old_obj->size();
+  int original_size = size;
+  if (oop(old_obj)->blueprint()->is_redefining()) {
+    assert(oop(old_obj)->blueprint()->old_version() != NULL, "must not be null");
+    original_size = oop(old_obj)->size_given_klass(oop(old_obj)->blueprint()->old_version()->klass_part());
+  } else if (oop(old_obj)->blueprint()->new_version() != NULL) {
+    size = oop(old_obj)->size_given_klass(oop(old_obj)->blueprint()->new_version()->klass_part());
+  }
+
+  bool normalComparison = (old_obj + original_size < new_obj + size);
+
+  if (is_in_reserved(new_obj)) {
+    // Old and new address are in same space, so just compare the address.
+    // Must rescue if object moves towards the top of the space.
+    assert(space_index(old_obj) == space_index(new_obj), "old_obj and new_obj must be in same space");
+    return normalComparison;
+
+  } else {
+
+    assert(space_index(old_obj) != space_index(new_obj), "old_obj and new_obj must be in different spaces");
+
+    Generation* tenured_gen = GenCollectedHeap::heap()->get_gen(1);
+    if (tenured_gen->is_in_reserved(new_obj)) {
+      // Must never rescue when moving from the new into the old generation.
+      assert(GenCollectedHeap::heap()->get_gen(0)->is_in_reserved(old_obj), "old_obj must be in DefNewGeneration");
+      assert(space_index(old_obj) > space_index(new_obj), "must be");
+      return false;
+
+    } else if (tenured_gen->is_in_reserved(old_obj)) {
+      // Must always rescue when moving from the old into the new generation.
+      assert(GenCollectedHeap::heap()->get_gen(0)->is_in_reserved(new_obj), "new_obj must be in DefNewGeneration");
+      assert(space_index(old_obj) < space_index(new_obj), "must be");
+      return true;
+
+    } else {
+      // In the new generation, eden is located before the from space, so a
+      // simple pointer comparison is sufficient.
+      assert(GenCollectedHeap::heap()->get_gen(0)->is_in_reserved(old_obj), "old_obj must be in DefNewGeneration");
+      assert(GenCollectedHeap::heap()->get_gen(0)->is_in_reserved(new_obj), "new_obj must be in DefNewGeneration");
+      assert((normalComparison) == (space_index(old_obj) < space_index(new_obj)), "slow and fast computation must yield same result");
+      return normalComparison;
+    }
+  }
+}
+
+oop CompactibleSpace::rescue(oop old_obj) {
+  assert(must_rescue(old_obj, old_obj->forwardee()), "do not call otherwise");
+
+  int size = old_obj->size();
+  oop rescued_obj = (oop)resource_allocate_bytes(size * HeapWordSize);
+  Copy::aligned_disjoint_words((HeapWord*)old_obj, (HeapWord*)rescued_obj, size);
+
+  if (MarkSweep::_rescued_oops == NULL) {
+    MarkSweep::_rescued_oops = new GrowableArray<oop>(128);
+  }
+
+  MarkSweep::_rescued_oops->append(rescued_obj);
+  return rescued_obj;
+}
+
 void CompactibleSpace::adjust_pointers() {
   // Check first is there is any work to do.
   if (used() == 0) {
     return;   // Nothing to do.
   }
+  /* adjust all the interior pointers to point at the new locations of objects        
+  * Used by MarkSweep::mark_sweep_phase3() */                                        
 
-  SCAN_AND_ADJUST_POINTERS(adjust_obj_size);
+  HeapWord* q = bottom();                                                        
+  HeapWord* t = _end_of_live;  /* Established by "prepare_for_compaction". */        
+
+  assert(_first_dead <= _end_of_live, "Stands to reason, no?");                        
+
+  debug_only(HeapWord* prev_q = NULL);   
+  debug_only(HeapWord* prev_prev_q = NULL); 
+  debug_only(HeapWord* prev_prev_prev_q = NULL);   
+  if (q < t && _first_dead > q &&                                                
+    !oop(q)->is_gc_marked()) {                                                
+      /* we have a chunk of the space which hasn't moved and we've                
+      * reinitialized the mark word during the previous pass, so we can't        
+      * use is_gc_marked for the traversal. */                                        
+      HeapWord* end = _first_dead;                                                
+      
+        while (q < end) {                                                                
+          /* I originally tried to conjoin "block_start(q) == q" to the                
+          * assertion below, but that doesn't work, because you can't                
+          * accurately traverse previous objects to get to the current one                
+          * after their pointers (including pointers into permGen) have been        
+          * updated, until the actual compaction is done.  dld, 4/00 */                
+          assert(block_is_obj(q),                                                        
+            "should be at block boundaries, and should be looking at objs");        
+
+          VALIDATE_MARK_SWEEP_ONLY(MarkSweep::track_interior_pointers(oop(q)));     
+
+          /* point all the oops to the new location */     
+          size_t size = oop(q)->adjust_pointers();        
+          size = adjust_obj_size(size);        
+
+          VALIDATE_MARK_SWEEP_ONLY(MarkSweep::check_interior_pointers());           
+          VALIDATE_MARK_SWEEP_ONLY(MarkSweep::validate_live_oop(oop(q), size));     
+
+          debug_only(prev_prev_prev_q = prev_prev_q);  
+          debug_only(prev_prev_q = prev_q);  
+          debug_only(prev_q = q);  
+          q += size;                                                                
+        }                                                                                
+
+        // (tw) first_dead can be live object!
+        q = _first_dead;
+
+//        if (_first_dead == t) {                                                        
+//          q = t;                                                                        
+//        } else {                                                                        
+//          /* $$$ This is funky.  Using this to read the previously written                
+//          * LiveRange.  See also use below. */                                        
+//          q = (HeapWord*)oop(_first_dead)->mark()->decode_pointer();                
+//        }                                                                               
+  }                                                                                
+
+  const intx interval = PrefetchScanIntervalInBytes;                            
+
+  debug_only(prev_q = NULL);  
+  debug_only(prev_prev_q = NULL); 
+  debug_only(prev_prev_prev_q = NULL);                                                 
+  while (q < t) {                                                                
+    /* prefetch beyond q */                                                        
+    Prefetch::write(q, interval);                                               
+    if (oop(q)->is_gc_marked()) {                                                
+      /* q is alive */                                                                
+      VALIDATE_MARK_SWEEP_ONLY(MarkSweep::track_interior_pointers(oop(q)));     
+      /* point all the oops to the new location */                                
+      size_t size = oop(q)->adjust_pointers();      
+      size = adjust_obj_size(size);                                                
+      VALIDATE_MARK_SWEEP_ONLY(MarkSweep::check_interior_pointers());                
+      VALIDATE_MARK_SWEEP_ONLY(MarkSweep::validate_live_oop(oop(q), size));     
+      debug_only(prev_prev_prev_q = prev_prev_q);  
+      debug_only(prev_prev_q = prev_q);  
+      debug_only(prev_q = q);                                                        
+      q += size;                                                                
+    } else {                                                                        
+      /* q is not a live object, so its mark should point at the next                
+      * live object */                              
+      debug_only(prev_prev_prev_q = prev_prev_q);  
+      debug_only(prev_prev_q = prev_q);                                    
+      debug_only(prev_q = q);                                                        
+      q = (HeapWord*) oop(q)->mark()->decode_pointer();                                
+      assert(q > prev_q, "we should be moving forward through memory");                
+    }                                                                                
+  }                                                                                
+
+  assert(q == t, "just checking");     
 }
 
 void CompactibleSpace::compact() {
-  SCAN_AND_COMPACT(obj_size);
+
+  if(!Universe::is_redefining_gc_run()) {
+    SCAN_AND_COMPACT(obj_size);
+    return;
+  } 
+
+  /* Copy all live objects to their new location
+   * Used by MarkSweep::mark_sweep_phase4() */
+  
+  HeapWord*       q = bottom();
+  HeapWord* const t = _end_of_live; 
+  debug_only(HeapWord* prev_q = NULL);    
+  
+  if (q < t && _first_dead > q &&                                                
+      !oop(q)->is_gc_marked()) {
+    debug_only(
+    /* we have a chunk of the space which hasn't moved and we've reinitialized  
+     * the mark word during the previous pass, so we can't use is_gc_marked for 
+     * the traversal. */                                                        
+    HeapWord* const end = _first_dead;                                                
+
+    while (q < end) {
+      size_t size = obj_size(q); // FIXME: idubrov oop(q)->size();
+      assert(!oop(q)->is_gc_marked(),                                           
+             "should be unmarked (special dense prefix handling)");             
+      VALIDATE_MARK_SWEEP_ONLY(MarkSweep::live_oop_moved_to(q, size, q));     
+      debug_only(prev_q = q);                                                        
+      q += size;                                                                
+    }  
+    )  /* debug_only */
+    // (tw) first_dead can be live object!
+    q = _first_dead;
+
+    //if (_first_dead == t) {                                                        
+    //  q = t;                                                                        
+    //} else {                                                                        
+    ///* $$$ Funky */                                                                 
+    //q = (HeapWord*) oop(_first_dead)->mark()->decode_pointer();                
+    //}                                                                                
+  }                                                                                
+  
+  const intx scan_interval = PrefetchScanIntervalInBytes;                        
+  const intx copy_interval = PrefetchCopyIntervalInBytes;                        
+  while (q < t) {                                                                
+    if (!oop(q)->is_gc_marked()) {                                                
+      /* mark is pointer to next marked oop */     
+      debug_only(prev_q = q);                                                        
+      q = (HeapWord*) oop(q)->mark()->decode_pointer();                                
+      assert(q > prev_q, "we should be moving forward through memory");                
+    } else {                                                                        
+      /* prefetch beyond q */                                                        
+      Prefetch::read(q, scan_interval);
+   
+      /* size and destination */                                                
+      size_t size = obj_size(q);                                                
+      HeapWord* compaction_top = (HeapWord*)oop(q)->forwardee(); 
+
+      if (must_rescue(oop(q), oop(q)->forwardee())) {
+        oop dest_obj = rescue(oop(q));
+        debug_only(Copy::fill_to_words(q, size, 0));
+      } else {
+
+        /* prefetch beyond compaction_top */                                        
+        Prefetch::write(compaction_top, copy_interval);                           
+        
+        /* copy object and reinit its mark */                                        
+        VALIDATE_MARK_SWEEP_ONLY(MarkSweep::live_oop_moved_to(q, size,            
+                                                              compaction_top));   
+        assert(q != compaction_top || oop(q)->blueprint()->new_version() != NULL, "everything in this pass should be moving");        
+        
+        if (oop(q)->blueprint()->new_version() != NULL) {
+          MarkSweep::update_fields(oop(q), oop(compaction_top));
+        } else {
+          Copy::aligned_conjoint_words(q, compaction_top, size);
+        }
+        oop(compaction_top)->init_mark();                                                
+        assert(oop(compaction_top)->klass() != NULL, "should have a class");
+      }
+
+      debug_only(prev_q = q);               
+      q += size;                                                                
+    }                                                                                
+  }                        
+  
+  /* Let's remember if we were empty before we did the compaction. */
+  bool was_empty = used_region().is_empty();
+  /* Reset space after compaction is complete */
+  reset_after_compaction();
+  /* We do this clear, below, since it has overloaded meanings for some */
+  /* space subtypes.  For example, OffsetTableContigSpace's that were   */
+  /* compacted into will have had their offset table thresholds updated */
+  /* continuously, but those that weren't need to have their thresholds */
+  /* re-initialized.  Also mangles unused area for debugging.           */
+  if (used_region().is_empty()) {
+    if (!was_empty) clear(SpaceDecorator::Mangle);
+  } else {
+    if (ZapUnusedHeapArea) mangle_unused_area();
+  }
+
+  //SCAN_AND_COMPACT(obj_size);
 }
 
 void Space::print_short() const { print_short_on(tty); }
diff --git a/src/share/vm/memory/space.hpp b/src/share/vm/memory/space.hpp
--- a/src/share/vm/memory/space.hpp
+++ b/src/share/vm/memory/space.hpp
@@ -445,6 +445,9 @@
   // indicates when the next such action should be taken.
   virtual void prepare_for_compaction(CompactPoint* cp);
   // MarkSweep support phase3
+  DEBUG_ONLY(int space_index(oop obj));
+  bool must_rescue(oop old_obj, oop new_obj);
+  oop rescue(oop old_obj);
   virtual void adjust_pointers();
   // MarkSweep support phase4
   virtual void compact();
@@ -475,6 +478,10 @@
   virtual HeapWord* forward(oop q, size_t size, CompactPoint* cp,
                     HeapWord* compact_top);
 
+  // (tw)
+  virtual HeapWord* forward_compact_top(size_t size, CompactPoint* cp,
+    HeapWord* compact_top);
+
   // Return a size with adjusments as required of the space.
   virtual size_t adjust_object_size_v(size_t size) const { return size; }
 
diff --git a/src/share/vm/memory/universe.cpp b/src/share/vm/memory/universe.cpp
--- a/src/share/vm/memory/universe.cpp
+++ b/src/share/vm/memory/universe.cpp
@@ -100,6 +100,8 @@
 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
 #endif
 
+bool Universe::_is_redefining_gc_run = false;
+
 // Known objects
 klassOop Universe::_boolArrayKlassObj                 = NULL;
 klassOop Universe::_byteArrayKlassObj                 = NULL;
@@ -203,6 +205,38 @@
   f(systemObjArrayKlassObj());
 }
 
+// DCEVM: This method should iterate all pointers that are not within heap objects.
+void Universe::root_oops_do(OopClosure *oopClosure) {
+
+  class AlwaysTrueClosure: public BoolObjectClosure {
+  public:
+    void do_object(oop p) { ShouldNotReachHere(); }
+    bool do_object_b(oop p) { return true; }
+  };
+  AlwaysTrueClosure always_true;
+
+  // General strong roots
+  Universe::oops_do(oopClosure);
+  JNIHandles::oops_do(oopClosure);
+  Threads::oops_do(oopClosure, NULL);
+  ObjectSynchronizer::oops_do(oopClosure);
+  FlatProfiler::oops_do(oopClosure);
+  //Management::oops_do(oopClosure); // DCEVM: TODO: Check if this is correct?
+  JvmtiExport::oops_do(oopClosure);
+  // SO_AllClasses
+  SystemDictionary::oops_do(oopClosure);
+  
+  // Now adjust pointers in remaining weak roots.  (All of which should
+  // have been cleared if they pointed to non-surviving objects.)
+  // Global (weak) JNI handles
+  JNIHandles::weak_oops_do(&always_true, oopClosure);
+  
+  CodeCache::oops_do(oopClosure);
+  StringTable::oops_do(oopClosure);
+  //ref_processor()->weak_oops_do(&oopClosure); // DCEVM: TODO: Check if this is correct?
+  //PSScavenge::reference_processor()->weak_oops_do(&oopClosure); // DCEVM: TODO: Check if this is correct?
+}
+
 void Universe::oops_do(OopClosure* f, bool do_all) {
 
   f->do_oop((oop*) &_int_mirror);
diff --git a/src/share/vm/memory/universe.hpp b/src/share/vm/memory/universe.hpp
--- a/src/share/vm/memory/universe.hpp
+++ b/src/share/vm/memory/universe.hpp
@@ -127,6 +127,8 @@
   friend class SystemDictionary;
   friend class VMStructs;
   friend class CompactingPermGenGen;
+  friend class Space;
+  friend class ContiguousSpace;
   friend class VM_PopulateDumpSharedSpace;
 
   friend jint  universe_init();
@@ -257,7 +259,18 @@
 
   static void compute_verify_oop_data();
 
+  static bool _is_redefining_gc_run;
+
  public:
+
+   static bool is_redefining_gc_run() {
+     return _is_redefining_gc_run;
+   }
+
+   static void set_redefining_gc_run(bool b) {
+     _is_redefining_gc_run = b;
+   }
+
   // Known classes in the VM
   static klassOop boolArrayKlassObj()                 { return _boolArrayKlassObj;   }
   static klassOop byteArrayKlassObj()                 { return _byteArrayKlassObj;   }
@@ -396,6 +409,8 @@
 
   // Iteration
 
+  static void root_oops_do(OopClosure *f);
+
   // Apply "f" to the addresses of all the direct heap pointers maintained
   // as static fields of "Universe".
   static void oops_do(OopClosure* f, bool do_all = false);
@@ -412,6 +427,7 @@
 
   // Debugging
   static bool verify_in_progress() { return _verify_in_progress; }
+  static void set_verify_in_progress(bool b) { _verify_in_progress = b; }
   static void verify(bool allow_dirty = true, bool silent = false,
                      VerifyOption option = VerifyOption_Default );
   static int  verify_count()       { return _verify_count; }
diff --git a/src/share/vm/oops/arrayKlass.cpp b/src/share/vm/oops/arrayKlass.cpp
--- a/src/share/vm/oops/arrayKlass.cpp
+++ b/src/share/vm/oops/arrayKlass.cpp
@@ -129,9 +129,9 @@
 
 bool arrayKlass::compute_is_subtype_of(klassOop k) {
   // An array is a subtype of Serializable, Clonable, and Object
-  return    k == SystemDictionary::Object_klass()
-         || k == SystemDictionary::Cloneable_klass()
-         || k == SystemDictionary::Serializable_klass();
+  return    k->klass_part()->newest_version() == SystemDictionary::Object_klass()->klass_part()->newest_version()
+         || k->klass_part()->newest_version() == SystemDictionary::Cloneable_klass()->klass_part()->newest_version()
+         || k->klass_part()->newest_version() == SystemDictionary::Serializable_klass()->klass_part()->newest_version();
 }
 
 
diff --git a/src/share/vm/oops/constMethodKlass.cpp b/src/share/vm/oops/constMethodKlass.cpp
--- a/src/share/vm/oops/constMethodKlass.cpp
+++ b/src/share/vm/oops/constMethodKlass.cpp
@@ -101,6 +101,7 @@
   MarkSweep::mark_and_push(cm->adr_method());
   MarkSweep::mark_and_push(cm->adr_stackmap_data());
   MarkSweep::mark_and_push(cm->adr_exception_table());
+  MarkSweep::mark_and_push(cm->adr_code_section_table());
   // Performance tweak: We skip iterating over the klass pointer since we
   // know that Universe::constMethodKlassObj never moves.
 }
@@ -113,6 +114,7 @@
   PSParallelCompact::mark_and_push(cm, cm_oop->adr_method());
   PSParallelCompact::mark_and_push(cm, cm_oop->adr_stackmap_data());
   PSParallelCompact::mark_and_push(cm, cm_oop->adr_exception_table());
+  PSParallelCompact::mark_and_push(cm, cm_oop->adr_code_section_table());
   // Performance tweak: We skip iterating over the klass pointer since we
   // know that Universe::constMethodKlassObj never moves.
 }
@@ -124,6 +126,7 @@
   blk->do_oop(cm->adr_method());
   blk->do_oop(cm->adr_stackmap_data());
   blk->do_oop(cm->adr_exception_table());
+  blk->do_oop(cm->adr_code_section_table());
   // Get size before changing pointers.
   // Don't call size() or oop_size() since that is a virtual call.
   int size = cm->object_size();
@@ -141,6 +144,8 @@
   if (mr.contains(adr)) blk->do_oop(adr);
   adr = cm->adr_exception_table();
   if (mr.contains(adr)) blk->do_oop(adr);
+  adr = cm->adr_code_section_table();
+  if (mr.contains(adr)) blk->do_oop(adr);
   // Get size before changing pointers.
   // Don't call size() or oop_size() since that is a virtual call.
   int size = cm->object_size();
@@ -156,6 +161,7 @@
   MarkSweep::adjust_pointer(cm->adr_method());
   MarkSweep::adjust_pointer(cm->adr_stackmap_data());
   MarkSweep::adjust_pointer(cm->adr_exception_table());
+  MarkSweep::adjust_pointer(cm->adr_code_section_table());
   // Get size before changing pointers.
   // Don't call size() or oop_size() since that is a virtual call.
   int size = cm->object_size();
diff --git a/src/share/vm/oops/constMethodOop.hpp b/src/share/vm/oops/constMethodOop.hpp
--- a/src/share/vm/oops/constMethodOop.hpp
+++ b/src/share/vm/oops/constMethodOop.hpp
@@ -114,7 +114,7 @@
 
 public:
   oop* oop_block_beg() const { return adr_method(); }
-  oop* oop_block_end() const { return adr_exception_table() + 1; }
+  oop* oop_block_end() const { return adr_code_section_table() + 1; }
 
 private:
   //
@@ -132,6 +132,10 @@
   // table is pointing to Universe::the_empty_int_array
   typeArrayOop      _exception_table;
 
+
+  // (tw) Table mapping code sections for method forward points.
+  typeArrayOop      _code_section_table;
+
   //
   // End of the oop block.
   //
@@ -184,6 +188,28 @@
   void set_exception_table(typeArrayOop e)       { oop_store_without_check((oop*) &_exception_table, (oop) e); }
   bool has_exception_handler() const             { return exception_table() != NULL && exception_table()->length() > 0; }
 
+  // code section table
+  typeArrayOop code_section_table() const         { return _code_section_table; }
+  void set_code_section_table(typeArrayOop e)     { oop_store_without_check((oop*) &_code_section_table, (oop) e); }
+  bool has_code_section_table() const             { return code_section_table() != NULL && code_section_table()->length() > 0; }
+  static const int ValuesPerCodeSectionEntry = 3;
+  int code_section_entries() const {
+    if (!has_code_section_table()) return 0;
+    return _code_section_table->length() / ValuesPerCodeSectionEntry;
+  }
+
+  int code_section_new_index_at(int index) const {
+    return _code_section_table->short_at(index * ValuesPerCodeSectionEntry);
+  }
+
+  int code_section_original_index_at(int index) const {
+    return _code_section_table->short_at(index * ValuesPerCodeSectionEntry + 1);
+  }
+
+  int code_section_length_at(int index) const {
+    return _code_section_table->short_at(index * ValuesPerCodeSectionEntry + 2);
+  }
+
   void init_fingerprint() {
     const uint64_t initval = CONST64(0x8000000000000000);
     _fingerprint = initval;
@@ -285,6 +311,7 @@
   oop*  adr_method() const             { return (oop*)&_method;          }
   oop*  adr_stackmap_data() const      { return (oop*)&_stackmap_data;   }
   oop*  adr_exception_table() const    { return (oop*)&_exception_table; }
+  oop*  adr_code_section_table() const { return (oop*)&_code_section_table; }
   bool is_conc_safe() { return _is_conc_safe; }
   void set_is_conc_safe(bool v) { _is_conc_safe = v; }
 
diff --git a/src/share/vm/oops/cpCacheOop.cpp b/src/share/vm/oops/cpCacheOop.cpp
--- a/src/share/vm/oops/cpCacheOop.cpp
+++ b/src/share/vm/oops/cpCacheOop.cpp
@@ -36,9 +36,15 @@
 
 // Implememtation of ConstantPoolCacheEntry
 
+void ConstantPoolCacheEntry::copy_from(ConstantPoolCacheEntry *other) {
+  _flags = other->_flags;    // flags
+}
+
 void ConstantPoolCacheEntry::initialize_entry(int index) {
   assert(0 < index && index < 0x10000, "sanity check");
   _indices = index;
+  _f1 = NULL;
+  _f2 = 0;
   assert(constant_pool_index() == index, "");
 }
 
@@ -50,7 +56,7 @@
 
 int ConstantPoolCacheEntry::as_flags(TosState state, bool is_final,
                     bool is_vfinal, bool is_volatile,
-                    bool is_method_interface, bool is_method) {
+                    bool is_method_interface, bool is_method, bool is_old_method) {
   int f = state;
 
   assert( state < number_of_states, "Invalid state in as_flags");
@@ -65,7 +71,9 @@
   if (is_method_interface) f |= 1;
   f <<= 1;
   if (is_method) f |= 1;
-  f <<= ConstantPoolCacheEntry::hotSwapBit;
+  f <<= 1;
+  if (is_old_method) f |= 1;
+  f <<= ConstantPoolCacheEntry::oldMethodBit;
   // Preserve existing flag bit values
 #ifdef ASSERT
   int old_state = ((_flags >> tosBits) & 0x0F);
@@ -137,7 +145,7 @@
   set_f2(field_offset);
   assert(field_index <= field_index_mask,
          "field index does not fit in low flag bits");
-  set_flags(as_flags(field_type, is_final, false, is_volatile, false, false) |
+  set_flags(as_flags(field_type, is_final, false, is_volatile, false, false, false) |
             (field_index & field_index_mask));
   set_bytecode_1(get_code);
   set_bytecode_2(put_code);
@@ -153,7 +161,8 @@
                                         int vtable_index) {
   assert(!is_secondary_entry(), "");
   assert(method->interpreter_entry() != NULL, "should have been set at this point");
-  assert(!method->is_obsolete(),  "attempt to write obsolete method to cpCache");
+  // (tw) No longer valid assert
+  //assert(!method->is_obsolete(),  "attempt to write obsolete method to cpCache");
   bool change_to_virtual = (invoke_code == Bytecodes::_invokeinterface);
 
   int byte_no = -1;
@@ -167,6 +176,9 @@
         } else {
           assert(vtable_index >= 0, "valid index");
           set_f2(vtable_index);
+
+          // (tw) save method holder in f1 for virtual calls
+          set_f1(method());
         }
         byte_no = 2;
         break;
@@ -212,7 +224,7 @@
                      needs_vfinal_flag,
                      false,
                      change_to_virtual,
-                     true)|
+                     true, method->is_old())|
             method()->size_of_parameters());
 
   // Note:  byte_no also appears in TemplateTable::resolve.
@@ -252,7 +264,7 @@
   assert(instanceKlass::cast(interf)->is_interface(), "must be an interface");
   set_f1(interf);
   set_f2(index);
-  set_flags(as_flags(as_TosState(method->result_type()), method->is_final_method(), false, false, false, true) | method()->size_of_parameters());
+  set_flags(as_flags(as_TosState(method->result_type()), method->is_final_method(), false, false, false, true, method->is_old()) | method()->size_of_parameters());
   set_bytecode_1(Bytecodes::_invokeinterface);
 }
 
@@ -282,7 +294,7 @@
   param_size -= 1;  // do not count MH.this; it is not stacked for invokedynamic
   bool is_final = true;
   assert(signature_invoker->is_final_method(), "is_final");
-  int flags = as_flags(as_TosState(signature_invoker->result_type()), is_final, false, false, false, true) | param_size;
+  int flags = as_flags(as_TosState(signature_invoker->result_type()), is_final, false, false, false, true, false) | param_size;
   assert(_flags == 0 || _flags == flags, "flags should be the same");
   set_flags(flags);
   // do not do set_bytecode on a secondary CP cache entry
@@ -416,26 +428,13 @@
 // If this constantPoolCacheEntry refers to old_method then update it
 // to refer to new_method.
 bool ConstantPoolCacheEntry::adjust_method_entry(methodOop old_method,
-       methodOop new_method, bool * trace_name_printed) {
+       methodOop new_method) {
 
   if (is_vfinal()) {
+
     // virtual and final so f2() contains method ptr instead of vtable index
-    if (f2() == (intptr_t)old_method) {
-      // match old_method so need an update
-      _f2 = (intptr_t)new_method;
-      if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) {
-        if (!(*trace_name_printed)) {
-          // RC_TRACE_MESG macro has an embedded ResourceMark
-          RC_TRACE_MESG(("adjust: name=%s",
-            Klass::cast(old_method->method_holder())->external_name()));
-          *trace_name_printed = true;
-        }
-        // RC_TRACE macro has an embedded ResourceMark
-        RC_TRACE(0x00400000, ("cpc vf-entry update: %s(%s)",
-          new_method->name()->as_C_string(),
-          new_method->signature()->as_C_string()));
-      }
-
+    if((methodOop)f2() != NULL && ((methodOop)f2())->method_holder()->klass_part()->new_version()) {
+      initialize_entry(constant_pool_index());
       return true;
     }
 
@@ -443,65 +442,28 @@
     return false;
   }
 
-  if ((oop)_f1 == NULL) {
-    // NULL f1() means this is a virtual entry so bail out
-    // We are assuming that the vtable index does not need change.
+  // (tw) check how to update interface methods!
+  if (bytecode_1() == Bytecodes::_invokevirtual || bytecode_2() == Bytecodes::_invokevirtual) {
+      
+    if(((methodOop)f1())->method_holder()->klass_part()->new_version()) {
+      initialize_entry(constant_pool_index());
+      return true;
+    }
+
     return false;
   }
 
   if ((oop)_f1 == old_method) {
     _f1 = new_method;
-    if (RC_TRACE_IN_RANGE(0x00100000, 0x00400000)) {
-      if (!(*trace_name_printed)) {
-        // RC_TRACE_MESG macro has an embedded ResourceMark
-        RC_TRACE_MESG(("adjust: name=%s",
-          Klass::cast(old_method->method_holder())->external_name()));
-        *trace_name_printed = true;
-      }
-      // RC_TRACE macro has an embedded ResourceMark
-      RC_TRACE(0x00400000, ("cpc entry update: %s(%s)",
-        new_method->name()->as_C_string(),
-        new_method->signature()->as_C_string()));
-    }
-
+    return true;
+  } else if(_f1 != NULL && (bytecode_1() != Bytecodes::_invokeinterface && ((methodOop)f1())->method_holder()->klass_part()->new_version())) {
+    initialize_entry(constant_pool_index());
     return true;
   }
 
   return false;
 }
 
-bool ConstantPoolCacheEntry::is_interesting_method_entry(klassOop k) {
-  if (!is_method_entry()) {
-    // not a method entry so not interesting by default
-    return false;
-  }
-
-  methodOop m = NULL;
-  if (is_vfinal()) {
-    // virtual and final so _f2 contains method ptr instead of vtable index
-    m = (methodOop)_f2;
-  } else if ((oop)_f1 == NULL) {
-    // NULL _f1 means this is a virtual entry so also not interesting
-    return false;
-  } else {
-    if (!((oop)_f1)->is_method()) {
-      // _f1 can also contain a klassOop for an interface
-      return false;
-    }
-    m = (methodOop)_f1;
-  }
-
-  assert(m != NULL && m->is_method(), "sanity check");
-  if (m == NULL || !m->is_method() || m->method_holder() != k) {
-    // robustness for above sanity checks or method is not in
-    // the interesting class
-    return false;
-  }
-
-  // the method is in the interesting class so the entry is interesting
-  return true;
-}
-
 void ConstantPoolCacheEntry::print(outputStream* st, int index) const {
   // print separator
   if (index == 0) tty->print_cr("                 -------------");
@@ -542,38 +504,18 @@
 // RedefineClasses() API support:
 // If any entry of this constantPoolCache points to any of
 // old_methods, replace it with the corresponding new_method.
-void constantPoolCacheOopDesc::adjust_method_entries(methodOop* old_methods, methodOop* new_methods,
-                                                     int methods_length, bool * trace_name_printed) {
-
-  if (methods_length == 0) {
-    // nothing to do if there are no methods
-    return;
-  }
-
-  // get shorthand for the interesting class
-  klassOop old_holder = old_methods[0]->method_holder();
+void constantPoolCacheOopDesc::adjust_entries(methodOop* old_methods, methodOop* new_methods,
+                                                     int methods_length) {
 
   for (int i = 0; i < length(); i++) {
-    if (!entry_at(i)->is_interesting_method_entry(old_holder)) {
-      // skip uninteresting methods
-      continue;
-    }
+     if (entry_at(i)->is_field_entry()) {
 
-    // The constantPoolCache contains entries for several different
-    // things, but we only care about methods. In fact, we only care
-    // about methods in the same class as the one that contains the
-    // old_methods. At this point, we have an interesting entry.
-
-    for (int j = 0; j < methods_length; j++) {
-      methodOop old_method = old_methods[j];
-      methodOop new_method = new_methods[j];
-
-      if (entry_at(i)->adjust_method_entry(old_method, new_method,
-          trace_name_printed)) {
-        // current old_method matched this entry and we updated it so
-        // break out and get to the next interesting entry if there one
-        break;
-      }
+       // (tw) TODO: Update only field offsets and modify only constant pool entries that
+       // point to changed fields
+       entry_at(i)->initialize_entry(entry_at(i)->constant_pool_index());
+     
+     } else if(entry_at(i)->is_method_entry()) {
+       entry_at(i)->adjust_method_entry(NULL, NULL);
     }
   }
 }
diff --git a/src/share/vm/oops/cpCacheOop.hpp b/src/share/vm/oops/cpCacheOop.hpp
--- a/src/share/vm/oops/cpCacheOop.hpp
+++ b/src/share/vm/oops/cpCacheOop.hpp
@@ -135,19 +135,24 @@
   void set_bytecode_2(Bytecodes::Code code);
   void set_f1(oop f1)                            {
     oop existing_f1 = _f1; // read once
-    assert(existing_f1 == NULL || existing_f1 == f1, "illegal field change");
+    // (tw) need to relax assertion for redefinition
+    // assert(existing_f1 == NULL || existing_f1 == f1, "illegal field change");
     oop_store(&_f1, f1);
   }
   void set_f1_if_null_atomic(oop f1);
-  void set_f2(intx f2)                           { assert(_f2 == 0    || _f2 == f2, "illegal field change"); _f2 = f2; }
+  void set_f2(intx f2)                           { 
+    // (tw) need to relax assertion for redefinition
+    // assert(_f2 == 0    || _f2 == f2, "illegal field change");
+    _f2 = f2; }
   int as_flags(TosState state, bool is_final, bool is_vfinal, bool is_volatile,
-               bool is_method_interface, bool is_method);
+               bool is_method_interface, bool is_method, bool is_old_method);
   void set_flags(intx flags)                     { _flags = flags; }
 
  public:
   // specific bit values in flag field
   // Note: the interpreter knows this layout!
   enum FlagBitValues {
+    oldMethodBit  = 22,
     hotSwapBit    = 23,
     methodInterface = 24,
     volatileField = 25,
@@ -167,6 +172,8 @@
   void initialize_entry(int original_index);     // initialize primary entry
   void initialize_secondary_entry(int main_index); // initialize secondary entry
 
+  void copy_from(ConstantPoolCacheEntry *other);
+
   void set_field(                                // sets entry to resolved field state
     Bytecodes::Code get_code,                    // the bytecode used for reading the field
     Bytecodes::Code put_code,                    // the bytecode used for writing the field
@@ -296,9 +303,7 @@
   // trace_name_printed is set to true if the current call has
   // printed the klass name so that other routines in the adjust_*
   // group don't print the klass name.
-  bool adjust_method_entry(methodOop old_method, methodOop new_method,
-         bool * trace_name_printed);
-  bool is_interesting_method_entry(klassOop k);
+  bool adjust_method_entry(methodOop old_method, methodOop new_method);
   bool is_field_entry() const                    { return (_flags & (1 << hotSwapBit)) == 0; }
   bool is_method_entry() const                   { return (_flags & (1 << hotSwapBit)) != 0; }
 
@@ -397,14 +402,9 @@
     return (base_offset() + ConstantPoolCacheEntry::size_in_bytes() * index);
   }
 
-  // RedefineClasses() API support:
-  // If any entry of this constantPoolCache points to any of
-  // old_methods, replace it with the corresponding new_method.
-  // trace_name_printed is set to true if the current call has
-  // printed the klass name so that other routines in the adjust_*
-  // group don't print the klass name.
-  void adjust_method_entries(methodOop* old_methods, methodOop* new_methods,
-                             int methods_length, bool * trace_name_printed);
+  // (tw) Update method and field references
+  void adjust_entries(methodOop* old_methods, methodOop* new_methods,
+                             int methods_length);
 };
 
 #endif // SHARE_VM_OOPS_CPCACHEOOP_HPP
diff --git a/src/share/vm/oops/instanceKlass.cpp b/src/share/vm/oops/instanceKlass.cpp
--- a/src/share/vm/oops/instanceKlass.cpp
+++ b/src/share/vm/oops/instanceKlass.cpp
@@ -248,12 +248,118 @@
 }
 
 
+void instanceKlass::initialize_redefined_class() {
+  RC_TRACE(0x00000400, ("initializing redefined class %s",
+    name()->as_C_string()));
+  
+  assert(!is_initialized(), "");
+  assert(this->old_version() != NULL, "");
+  assert(is_linked(), "must be linked before");
+
+
+  instanceKlassHandle this_oop(Thread::current(), this->as_klassOop());
+  class UpdateStaticFieldClosure : public FieldClosure {
+
+  private:
+    instanceKlassHandle this_oop;
+
+  public:
+    UpdateStaticFieldClosure(instanceKlassHandle this_oop) {
+      this->this_oop = this_oop;
+    }
+
+    virtual void do_field(fieldDescriptor* fd) {
+      fieldDescriptor result;
+      bool found = ((instanceKlass *)(this_oop->old_version()->klass_part()))->find_local_field(fd->name(), fd->signature(), &result);
+    
+      if (found && result.is_static()) {
+        int old_offset = result.offset();
+        assert(result.field_type() == fd->field_type(), "Old and new field type does not match");
+
+        oop new_location = this_oop()->java_mirror();
+        oop old_location = this_oop->old_version()->java_mirror();
+        int offset = fd->offset();
+        RC_TRACE(0x00000400, ("Copying static field value for field '%s' old_offset=%d new_offset=%d",
+          fd->name()->as_C_string(), old_offset, offset));
+
+        oop cur_oop;
+
+        switch(result.field_type()) {
+
+          // Found static field with same name and type in the old klass => copy value from old to new klass
+        
+          case T_BOOLEAN:
+            new_location->bool_field_put(offset, old_location->bool_field(old_offset));
+            DEBUG_ONLY(old_location->byte_field_put(old_offset, 0));
+            break;
+
+          case T_CHAR:
+            new_location->char_field_put(offset, old_location->char_field(old_offset));
+            DEBUG_ONLY(old_location->char_field_put(old_offset, 0));
+            break;
+
+          case T_FLOAT:
+            new_location->float_field_put(offset, old_location->float_field(old_offset));
+            DEBUG_ONLY(old_location->float_field_put(old_offset, 0));
+            break;
+
+          case T_DOUBLE:
+            new_location->double_field_put(offset, old_location->double_field(old_offset));
+            DEBUG_ONLY(old_location->double_field_put(old_offset, 0));
+            break;
+
+          case T_BYTE:
+            new_location->byte_field_put(offset, old_location->byte_field(old_offset));
+            DEBUG_ONLY(old_location->byte_field_put(old_offset, 0));
+            break;
+
+          case T_SHORT:
+            new_location->short_field_put(offset, old_location->short_field(old_offset));
+            DEBUG_ONLY(old_location->short_field_put(old_offset, 0));
+            break;
+
+          case T_INT:
+            new_location->int_field_put(offset, old_location->int_field(old_offset));
+            DEBUG_ONLY(old_location->int_field_put(old_offset, 0));
+            break;
+
+          case T_LONG:
+            new_location->long_field_put(offset, old_location->long_field(old_offset));
+            DEBUG_ONLY(old_location->long_field_put(old_offset, 0));
+            break;
+
+          case T_OBJECT:
+          case T_ARRAY:
+            cur_oop = old_location->obj_field(old_offset);
+            new_location->obj_field_put_raw(offset, cur_oop);
+            old_location->obj_field_put_raw(old_offset, NULL);
+            break;
+
+          default:
+            ShouldNotReachHere();
+        }
+      } else {
+        RC_TRACE(0x00000200, ("New static field %s has_initial_value=%d",
+          fd->name()->as_C_string(), (int)(fd->has_initial_value())));
+        // field not found
+        // (tw) TODO: Probably this call is not necessary here!
+        // FIXME: idubrov
+        //ClassFileParser::initialize_static_field(fd, Thread::current());
+      }
+    }
+  };
+
+  UpdateStaticFieldClosure cl(this_oop);
+  this->do_local_static_fields(&cl);
+}
+
+
 bool instanceKlass::verify_code(
     instanceKlassHandle this_oop, bool throw_verifyerror, TRAPS) {
   // 1) Verify the bytecodes
   Verifier::Mode mode =
     throw_verifyerror ? Verifier::ThrowException : Verifier::NoException;
-  return Verifier::verify(this_oop, mode, this_oop->should_verify_class(), CHECK_false);
+  return Verifier::verify(this_oop, mode, this_oop->should_verify_class(), true, CHECK_false);
 }
 
 
@@ -360,7 +466,13 @@
                                    jt->get_thread_stat()->perf_recursion_counts_addr(),
                                    jt->get_thread_stat()->perf_timers_addr(),
                                    PerfClassTraceTime::CLASS_VERIFY);
-          bool verify_ok = verify_code(this_oop, throw_verifyerror, THREAD);
+          if (this_oop->is_redefining()) {
+            Thread::current()->set_pretend_new_universe(true);
+          }
+          bool verify_ok  = verify_code(this_oop, throw_verifyerror, THREAD);
+          if (this_oop->is_redefining()) {
+            Thread::current()->set_pretend_new_universe(false);
+          }
           if (!verify_ok) {
             return false;
           }
@@ -398,7 +510,8 @@
       }
 #endif
       this_oop->set_init_state(linked);
-      if (JvmtiExport::should_post_class_prepare()) {
+      // (tw) Must check for old version in order to prevent infinite loops.
+      if (JvmtiExport::should_post_class_prepare() && this_oop->old_version() == NULL /* JVMTI deadlock otherwise */) {
         Thread *thread = THREAD;
         assert(thread->is_Java_thread(), "thread->is_Java_thread()");
         JvmtiExport::post_class_prepare((JavaThread *) thread, this_oop());
@@ -665,6 +778,18 @@
   return false;
 }
 
+bool instanceKlass::implements_interface_any_version(klassOop k) const {
+  k = k->klass_part()->newest_version();
+  if (this->newest_version() == k) return true;
+  assert(Klass::cast(k)->is_interface(), "should be an interface class");
+  for (int i = 0; i < transitive_interfaces()->length(); i++) {
+    if (((klassOop)transitive_interfaces()->obj_at(i))->klass_part()->newest_version() == k) {
+      return true;
+    }
+  }
+  return false;
+}
+
 objArrayOop instanceKlass::allocate_objArray(int n, int length, TRAPS) {
   if (length < 0) THROW_0(vmSymbols::java_lang_NegativeArraySizeException());
   if (length > arrayOopDesc::max_array_length(T_OBJECT)) {
@@ -793,7 +918,25 @@
 }
 
 void instanceKlass::call_class_initializer_impl(instanceKlassHandle this_oop, TRAPS) {
+
+  ResourceMark rm(THREAD);
   methodHandle h_method(THREAD, this_oop->class_initializer());
+
+  if (this_oop->revision_number() != -1){
+    methodOop m = NULL;
+    if (AllowAdvancedClassRedefinition) {
+      m = this_oop->find_method(vmSymbols::static_transformer_name(), vmSymbols::void_method_signature());
+    }
+    methodHandle method(m);
+    if (method() != NULL && method()->is_static()) {
+      RC_TRACE(0x00000200, ("Calling static transformer instead of static initializer"));
+      h_method = method;
+    } else if (!((instanceKlass*)this_oop->old_version()->klass_part())->is_not_initialized()) {
+      // Only execute the static initializer, if it was not yet executed for the old version of the class.
+      return;
+    }
+  }
+
   assert(!this_oop->is_initialized(), "we cannot initialize twice");
   if (TraceClassInitialization) {
     tty->print("%d Initializing ", call_class_initializer_impl_counter++);
@@ -942,6 +1085,137 @@
   }
 }
 
+void instanceKlass::store_update_information(GrowableArray<int> &values) {
+  int *arr = NEW_C_HEAP_ARRAY(int, values.length());
+  for (int i=0; i<values.length(); i++) {
+    arr[i] = values.at(i);
+  }
+  set_update_information(arr);
+}
+
+void instanceKlass::clear_update_information() {
+  FREE_C_HEAP_ARRAY(int, update_information());
+  set_update_information(NULL);
+}
+
+typedef Pair<int, klassOop> typeInfoPair;
+
+void instanceKlass::store_type_check_information(GrowableArray< Pair<int, klassOop> > &values) {
+  Pair<int, klassOop> *arr = NEW_C_HEAP_ARRAY(typeInfoPair, values.length());
+  for (int i=0; i<values.length(); i++) {
+    arr[i] = values.at(i);
+  }
+  set_type_check_information(arr);
+}
+
+void instanceKlass::clear_type_check_information() {
+  FREE_C_HEAP_ARRAY(typeInfoPair, type_check_information());
+  set_type_check_information(NULL);
+}
+
+void instanceKlass::do_fields_evolution(FieldEvolutionClosure* cl) {
+
+  assert (old_version() != NULL, "must have old version!");
+
+  klassOop old_klass_oop = old_version();
+  instanceKlass *old_klass = instanceKlass::cast(old_klass_oop);
+  instanceKlass *new_klass = this;
+
+  fieldDescriptor fd;
+  fieldDescriptor old_fd;
+
+  instanceKlass *cur_new_klass = new_klass;
+  klassOop cur_new_klass_oop = this->as_klassOop();
+
+  if (_fields_not_changed) {
+
+    class MyFieldClosure : public FieldClosure {
+
+      FieldEvolutionClosure *_cl;
+    public:
+      MyFieldClosure(FieldEvolutionClosure *cl) {_cl = cl; }
+      virtual void do_field(fieldDescriptor* fd) {
+        _cl->do_changed_field(fd, fd);
+      }
+    };
+
+    MyFieldClosure mfc(cl);
+    do_nonstatic_fields(&mfc);
+  } else {
+
+    _fields_not_changed = true;
+    GrowableArray<fieldDescriptor> fds;
+    while (true) {
+      for (JavaFieldStream fs(cur_new_klass); !fs.done(); fs.next()) {
+        fd.initialize(cur_new_klass_oop, fs.index());
+        if (fd.is_static()) {
+          continue;
+        }
+        fds.append(fd);
+      }
+
+      if (cur_new_klass->super() != NULL) {
+        cur_new_klass_oop = cur_new_klass->super();
+        cur_new_klass = instanceKlass::cast(cur_new_klass_oop);
+      } else {
+        break;
+      }
+    }
+
+    GrowableArray<fieldDescriptor> sortedFds;
+    while (fds.length() > 0) {
+      int minOffset = 0x7fffffff;
+      int minIndex = -1;
+      for (int i=0; i<fds.length(); i++) {
+        int curOffset = fds.adr_at(i)->offset();
+        if (curOffset < minOffset) {
+          minOffset = curOffset;
+          minIndex = i;
+        }
+      }
+
+      sortedFds.append(fds.at(minIndex));
+      fds.remove_at(minIndex);
+    }
+
+
+    for (int i=0; i<sortedFds.length(); i++) {
+      fieldDescriptor &fd = *sortedFds.adr_at(i);
+
+      char found = 0;
+      instanceKlass *cur_old_klass = old_klass;
+      klassOop cur_old_klass_oop = old_klass_oop;
+      while (true) {
+        for (JavaFieldStream fs(cur_old_klass); !fs.done(); fs.next()) {
+          old_fd.initialize(cur_old_klass_oop, fs.index());
+          if (old_fd.is_static()) {
+            continue;
+          }
+          if (old_fd.name() == fd.name() && old_fd.signature() == fd.signature()) {
+            found = 1;
+            break;
+          }
+        }
+        if (!found && cur_old_klass->super()) {
+          cur_old_klass_oop = cur_old_klass->super();
+          cur_old_klass = instanceKlass::cast(cur_old_klass_oop);
+        } else {
+          break;
+        }
+      }
+
+      if (found) {
+        if (old_fd.offset() != fd.offset()) {
+          _fields_not_changed = false;
+        }
+        cl->do_changed_field(&old_fd, &fd);
+      } else {
+        _fields_not_changed = false;
+        cl->do_new_field(&fd);
+      }
+    }
+  }
+}
 
 void instanceKlass::do_local_static_fields(FieldClosure* cl) {
   for (JavaFieldStream fs(this); !fs.done(); fs.next()) {
@@ -1331,6 +1605,20 @@
   return id;
 }
 
+bool instanceKlass::update_jmethod_id(methodOop method, jmethodID newMethodID) {
+  size_t idnum = (size_t)method->method_idnum();
+  jmethodID* jmeths = methods_jmethod_ids_acquire();
+  size_t length;                                // length assigned as debugging crumb
+  jmethodID id = NULL;
+  if (jmeths != NULL &&                         // If there is a cache
+    (length = (size_t)jmeths[0]) > idnum) {   // and if it is long enough,
+      jmeths[idnum+1] = newMethodID;                       // Set the id (may be NULL)
+      return true;
+  }
+
+  return false;
+}
+
 
 // Cache an itable index
 void instanceKlass::set_cached_itable_index(size_t idnum, int index) {
@@ -1490,6 +1778,13 @@
     last = b;
     b = b->next();
   }
+
+  // (tw) Hack as dependencies get wrong version of klassOop
+  if(this->old_version() != NULL) {
+    ((instanceKlass *)this->old_version()->klass_part())->remove_dependent_nmethod(nm);
+    return;
+  }
+
 #ifdef ASSERT
   tty->print_cr("### %s can't find dependent nmethod:", this->external_name());
   nm->print();
@@ -2337,6 +2632,9 @@
     klassOop mirrored_klass = java_lang_Class::as_klassOop(obj);
     st->print(BULLET"fake entry for mirror: ");
     mirrored_klass->print_value_on(st);
+    if (mirrored_klass != NULL) {
+      st->print_cr("revision: %d (oldest=%d, newest=%d)", mirrored_klass->klass_part()->revision_number(), mirrored_klass->klass_part()->oldest_version()->klass_part()->revision_number(), mirrored_klass->klass_part()->newest_version()->klass_part()->revision_number());
+    }
     st->cr();
     st->print(BULLET"fake entry resolved_constructor: ");
     methodOop ctor = java_lang_Class::resolved_constructor(obj);
diff --git a/src/share/vm/oops/instanceKlass.hpp b/src/share/vm/oops/instanceKlass.hpp
--- a/src/share/vm/oops/instanceKlass.hpp
+++ b/src/share/vm/oops/instanceKlass.hpp
@@ -99,6 +99,22 @@
   virtual void do_field(fieldDescriptor* fd) = 0;
 };
 
+// (tw) Iterates over the fields of the old and new class
+class FieldEvolutionClosure : public StackObj {
+public:
+  virtual void do_new_field(fieldDescriptor* fd) = 0;
+  virtual void do_old_field(fieldDescriptor* fd) = 0;
+  virtual void do_changed_field(fieldDescriptor* old_fd, fieldDescriptor *new_fd) = 0;
+};
+
+// (tw) Iterates over the methods of the old and new class
+class MethodEvolutionClosure : public StackObj {
+public:
+  virtual void do_new_method(methodOop oop) = 0;
+  virtual void do_old_method(methodOop oop) = 0;
+  virtual void do_changed_method(methodOop oldOop, methodOop newOop) = 0;
+};
+
 #ifndef PRODUCT
 // Print fields.
 // If "obj" argument to constructor is NULL, prints static fields, otherwise prints non-static fields.
@@ -264,6 +280,11 @@
   // _idnum_allocated_count.
   u1              _init_state;                    // state of class
 
+  // (tw) Field that allows for a short-path when calculating updated fields for the second time and
+  // no fields changed. Testing performance impact with this, can be removed later when the update
+  // information is cached.
+  bool            _fields_not_changed;
+
   u1              _reference_type;                // reference type
 
   // embedded Java vtable follows here
@@ -397,6 +418,7 @@
   // initialization (virtuals from Klass)
   bool should_be_initialized() const;  // means that initialize should be called
   void initialize(TRAPS);
+  void initialize_redefined_class();
   void link_class(TRAPS);
   bool link_class_or_fail(TRAPS); // returns false on failure
   void unlink_class();
@@ -549,6 +571,7 @@
   static void get_jmethod_id_length_value(jmethodID* cache, size_t idnum,
                 size_t *length_p, jmethodID* id_p);
   jmethodID jmethod_id_or_null(methodOop method);
+  bool update_jmethod_id(methodOop method, jmethodID newMethodID);
 
   // cached itable index support
   void set_cached_itable_index(size_t idnum, int index);
@@ -630,6 +653,7 @@
 
   // subclass/subinterface checks
   bool implements_interface(klassOop k) const;
+  bool implements_interface_any_version(klassOop k) const;
 
   // Access to implementors of an interface. We only store the count
   // of implementors, and in case, there are only a few
@@ -659,6 +683,12 @@
   void do_local_static_fields(FieldClosure* cl);
   void do_nonstatic_fields(FieldClosure* cl); // including inherited fields
   void do_local_static_fields(void f(fieldDescriptor*, TRAPS), TRAPS);
+  void do_fields_evolution(FieldEvolutionClosure *cl);
+  void store_update_information(GrowableArray<int> &values);
+  void clear_update_information();
+  void store_type_check_information(GrowableArray< Pair<int, klassOop> > &values);
+  void clear_type_check_information();
+
 
   void methods_do(void f(methodOop method));
   void array_klasses_do(void f(klassOop k));
diff --git a/src/share/vm/oops/instanceKlassKlass.cpp b/src/share/vm/oops/instanceKlassKlass.cpp
--- a/src/share/vm/oops/instanceKlassKlass.cpp
+++ b/src/share/vm/oops/instanceKlassKlass.cpp
@@ -451,6 +451,28 @@
   instanceKlass* ik = instanceKlass::cast(klassOop(obj));
   klassKlass::oop_print_on(obj, st);
 
+  // (tw) Output revision number and revision numbers of older / newer and oldest / newest version of this class.
+
+  st->print(BULLET"revision:          %d", ik->revision_number());                    
+  
+  if (ik->new_version() != NULL) {
+    st->print(" (newer=%d)", ik->new_version()->klass_part()->revision_number());
+  }
+
+  if (ik->newest_version() != ik->new_version() && ik->newest_version() != obj) {
+    st->print(" (newest=%d)", ik->newest_version()->klass_part()->revision_number());
+  }
+
+  if (ik->old_version() != NULL) {
+    st->print(" (old=%d)", ik->old_version()->klass_part()->revision_number());
+  }
+
+  if (ik->oldest_version() != ik->old_version() && ik->oldest_version() != obj) {
+    st->print(" (oldest=%d)", ik->oldest_version()->klass_part()->revision_number());
+  }
+
+  st->cr();
+  
   st->print(BULLET"instance size:     %d", ik->size_helper());                        st->cr();
   st->print(BULLET"klass size:        %d", ik->object_size());                        st->cr();
   st->print(BULLET"access:            "); ik->access_flags().print_on(st);            st->cr();
@@ -636,7 +658,7 @@
       }
       guarantee(sib->as_klassOop()->is_klass(), "should be klass");
       guarantee(sib->as_klassOop()->is_perm(),  "should be in permspace");
-      guarantee(sib->super() == super, "siblings should have same superklass");
+      guarantee(sib->super() == super || super->klass_part()->newest_version() == SystemDictionary::Object_klass(), "siblings should have same superklass");
       sib = sib->next_sibling();
     }
 
diff --git a/src/share/vm/oops/instanceRefKlass.cpp b/src/share/vm/oops/instanceRefKlass.cpp
--- a/src/share/vm/oops/instanceRefKlass.cpp
+++ b/src/share/vm/oops/instanceRefKlass.cpp
@@ -455,10 +455,13 @@
   instanceKlass* ik = instanceKlass::cast(k);
 
   // Check that we have the right class
-  debug_only(static bool first_time = true);
-  assert(k == SystemDictionary::Reference_klass() && first_time,
-         "Invalid update of maps");
-  debug_only(first_time = false);
+  
+  // (tw) Asserts no longer valid for class redefinition
+  // debug_only(static bool first_time = true);
+  
+  //assert(k == SystemDictionary::Reference_klass() && first_time,
+  //       "Invalid update of maps");
+  //debug_only(first_time = false);
   assert(ik->nonstatic_oop_map_count() == 1, "just checking");
 
   OopMapBlock* map = ik->start_of_nonstatic_oop_maps();
diff --git a/src/share/vm/oops/klass.cpp b/src/share/vm/oops/klass.cpp
--- a/src/share/vm/oops/klass.cpp
+++ b/src/share/vm/oops/klass.cpp
@@ -54,6 +54,26 @@
   return false;
 }
 
+void Klass::update_supers_to_newest_version() {
+
+  if (super() != NULL) set_super(super()->klass_part()->newest_version());
+  
+  for (uint i=0; i<primary_super_limit(); i++) {
+    klassOop cur = _primary_supers[i];
+    if (cur != NULL) {
+      _primary_supers[i] = cur->klass_part()->newest_version();
+    }
+  }
+
+  // Scan the array-of-objects 
+  int cnt = secondary_supers()->length();
+  for (int i = 0; i < cnt; i++) {
+    klassOop cur = (klassOop)secondary_supers()->obj_at(i);
+    if (cur != NULL) {
+      secondary_supers()->obj_at_put(i, cur->klass_part()->newest_version());
+    }
+  }
+}
 bool Klass::search_secondary_supers(klassOop k) const {
   // Put some extra logic here out-of-line, before the search proper.
   // This cuts down the size of the inline method.
@@ -160,6 +180,16 @@
   kl->set_alloc_size(0);
   TRACE_SET_KLASS_TRACE_ID(kl, 0);
 
+  kl->set_redefinition_flags(Klass::NoRedefinition);
+  kl->set_redefining(false);
+  kl->set_new_version(NULL);
+  kl->set_old_version(NULL);
+  kl->set_redefinition_index(-1);
+  kl->set_revision_number(-1);
+  kl->set_field_redefinition_policy(DynamicCheck);
+  kl->set_static_field_redefinition_policy(AccessDeletedMembers);
+  kl->set_method_redefinition_policy(AccessDeletedMembers);
+
   kl->set_prototype_header(markOopDesc::prototype());
   kl->set_biased_lock_revocation_count(0);
   kl->set_last_biased_lock_bulk_revocation_time(0);
@@ -232,7 +262,7 @@
     set_super(NULL);
     oop_store_without_check((oop*) &_primary_supers[0], (oop) this->as_klassOop());
     assert(super_depth() == 0, "Object must already be initialized properly");
-  } else if (k != super() || k == SystemDictionary::Object_klass()) {
+  } else if (k != super() || k->klass_part()->super() == NULL) {
     assert(super() == NULL || super() == SystemDictionary::Object_klass(),
            "initialize this only once to a non-trivial value");
     set_super(k);
diff --git a/src/share/vm/oops/klass.hpp b/src/share/vm/oops/klass.hpp
--- a/src/share/vm/oops/klass.hpp
+++ b/src/share/vm/oops/klass.hpp
@@ -170,6 +170,7 @@
   void* operator new(size_t ignored, KlassHandle& klass, int size, TRAPS);
 };
 
+template<class L, class R> class Pair;
 
 class Klass : public Klass_vtbl {
   friend class VMStructs;
@@ -222,6 +223,39 @@
   oop* oop_block_beg() const { return adr_secondary_super_cache(); }
   oop* oop_block_end() const { return adr_next_sibling() + 1; }
 
+  // (tw) Different class redefinition flags of code evolution.
+  enum RedefinitionFlags {
+
+    // This class is not redefined at all!
+    NoRedefinition,
+
+    // There are changes to the class meta data.
+    ModifyClass = 1,
+
+    // The size of the class meta data changes.
+    ModifyClassSize = ModifyClass << 1,
+
+    // There are change to the instance format.
+    ModifyInstances = ModifyClassSize << 1,
+
+    // The size of instances changes.
+    ModifyInstanceSize = ModifyInstances << 1,
+
+    // A super type of this class is removed.
+    RemoveSuperType = ModifyInstanceSize << 1,
+
+    // This class (or one of its super classes) has an instance transformer method.
+    HasInstanceTransformer = RemoveSuperType << 1,
+  };
+
+  // (tw) Different policies dealing with deleted fields / methods in old code.
+  enum RedefinitionPolicy {
+    StaticCheck,
+    DynamicCheck,
+    AccessDeletedMembers,
+    AccessOldMembers
+  };
+
  protected:
   //
   // The oop block.  All oop fields must be declared here and only oop fields
@@ -241,6 +275,10 @@
   oop       _java_mirror;
   // Superclass
   klassOop  _super;
+  // Old class
+  klassOop _old_version;
+  // New class
+  klassOop _new_version;
   // First subclass (NULL if none); _subklass->next_sibling() is next one
   klassOop _subklass;
   // Sibling link (or NULL); links all subklasses of a klass
@@ -253,6 +291,19 @@
   jint        _modifier_flags;  // Processed access flags, for use by Class.getModifiers.
   AccessFlags _access_flags;    // Access flags. The class/interface distinction is stored here.
 
+  // (tw) Non-oop fields for enhanced class redefinition
+  jint                  _revision_number;        // The revision number for redefined classes
+  jint                  _redefinition_index;     // Index of this class when performing the redefinition
+  bool                  _subtype_changed;
+  int                   _redefinition_flags;     // Level of class redefinition
+  bool                  _is_copying_backwards;   // Does the class need to copy fields backwards? => possibly overwrite itself?
+  int *                 _update_information;     // Update information
+  Pair<int, klassOop> * _type_check_information; // Offsets of object fields that need a type check
+  char                  _method_redefinition_policy;
+  char                  _field_redefinition_policy;
+  char                  _static_field_redefinition_policy;
+  bool                  _is_redefining;
+
 #ifndef PRODUCT
   int           _verify_count;  // to avoid redundant verifies
 #endif
@@ -301,6 +352,99 @@
   klassOop secondary_super_cache() const     { return _secondary_super_cache; }
   void set_secondary_super_cache(klassOop k) { oop_store_without_check((oop*) &_secondary_super_cache, (oop) k); }
 
+  // BEGIN class redefinition utilities
+
+  // double links between new and old version of a class
+  klassOop old_version() const                         { return _old_version; }
+  void set_old_version(klassOop klass)                 { assert(_old_version == NULL || klass == NULL, "Can only be set once!"); _old_version = klass; }
+  klassOop new_version() const                         { return _new_version; }
+  void set_new_version(klassOop klass)                 { assert(_new_version == NULL || klass == NULL, "Can only be set once!"); _new_version = klass; }
+
+  // A subtype of this class is no longer a subtype
+  bool has_subtype_changed() const                     { return _subtype_changed; }
+  void set_subtype_changed(bool b)                     { assert(is_newest_version() || new_version()->klass_part()->is_newest_version(), "must be newest or second newest version");
+                                                         _subtype_changed = b; }
+  // state of being redefined
+  int redefinition_index() const                       { return _redefinition_index; }
+  void set_redefinition_index(int index)               { _redefinition_index = index; }
+  void set_redefining(bool b)                          { _is_redefining = b; }
+  bool is_redefining() const                           { return _is_redefining; }
+  int redefinition_flags() const                       { return _redefinition_flags; }
+  bool check_redefinition_flag(int flags) const        { return (_redefinition_flags & flags) != 0; }
+  void set_redefinition_flags(int flags)               { _redefinition_flags = flags; }
+  bool is_copying_backwards() const                    { return _is_copying_backwards; }
+  void set_copying_backwards(bool b)                   { _is_copying_backwards = b; }
+
+  // update information
+  int *update_information() const                      { return _update_information; }
+  void set_update_information(int *info)               { _update_information = info; }
+  Pair<int, klassOop> *type_check_information() const        { return _type_check_information; }
+  void set_type_check_information(Pair<int, klassOop> *info) { _type_check_information = info; }
+
+  bool is_same_or_older_version(klassOop klass) const {
+    if (Klass::cast(klass) == this) { return true; }
+    else if (_old_version == NULL) { return false; }
+    else { return _old_version->klass_part()->is_same_or_older_version(klass); }
+  }
+
+  // Revision number for redefined classes, -1 for originally loaded classes
+  jint revision_number() const {
+    return _revision_number;
+  }
+
+  bool was_redefined() const {
+    return _revision_number != -1;
+  }
+
+  void set_revision_number(jint number) {
+    _revision_number = number;
+  }
+
+  char method_redefinition_policy() {
+    return _method_redefinition_policy;
+  }
+
+  void set_method_redefinition_policy(char v) {
+    _method_redefinition_policy = v;
+  }
+
+  char field_redefinition_policy() {
+    return _field_redefinition_policy;
+  }
+
+  void set_field_redefinition_policy(char v) {
+    _field_redefinition_policy = v;
+  }
+
+  char static_field_redefinition_policy() {
+	  return _static_field_redefinition_policy;
+  }
+
+  void set_static_field_redefinition_policy(char v) {
+	  _static_field_redefinition_policy = v;
+  }
+
+  klassOop oldest_version() const {
+    if (_old_version == NULL) { return this->as_klassOop(); }
+    else { return _old_version->klass_part()->oldest_version(); };
+  }
+
+  klassOop newest_version() const {
+    if (_new_version == NULL) { return this->as_klassOop(); }
+    else { return _new_version->klass_part()->newest_version(); };
+  }
+
+  klassOop active_version() const {
+    if (_new_version == NULL || _new_version->klass_part()->is_redefining()) { return this->as_klassOop(); assert(!this->is_redefining(), "just checking"); }
+    else { return _new_version->klass_part()->active_version(); };
+  }
+
+  bool is_newest_version() const {
+    return _new_version == NULL;
+  }
+
+  // END class redefinition utilities
+
   objArrayOop secondary_supers() const { return _secondary_supers; }
   void set_secondary_supers(objArrayOop k) { oop_store_without_check((oop*) &_secondary_supers, (oop) k); }
 
@@ -361,6 +505,8 @@
   void     set_next_sibling(klassOop s);
 
   oop* adr_super()           const { return (oop*)&_super;             }
+  oop* adr_old_version()           const { return (oop*)&_old_version; }
+  oop* adr_new_version()           const { return (oop*)&_new_version; }
   oop* adr_primary_supers()  const { return (oop*)&_primary_supers[0]; }
   oop* adr_secondary_super_cache() const { return (oop*)&_secondary_super_cache; }
   oop* adr_secondary_supers()const { return (oop*)&_secondary_supers;  }
@@ -490,6 +636,7 @@
       return search_secondary_supers(k);
     }
   }
+  void update_supers_to_newest_version();
   bool search_secondary_supers(klassOop k) const;
 
   // Find LCA in class hierarchy
@@ -818,6 +965,8 @@
 
 
 inline oop klassOopDesc::java_mirror() const                        { return klass_part()->java_mirror(); }
+inline klassOop klassOopDesc::old_version() const                   { return klass_part()->old_version(); }
+inline klassOop klassOopDesc::new_version() const                   { return klass_part()->new_version(); }
 
 
 #endif // SHARE_VM_OOPS_KLASS_HPP
diff --git a/src/share/vm/oops/klassKlass.cpp b/src/share/vm/oops/klassKlass.cpp
--- a/src/share/vm/oops/klassKlass.cpp
+++ b/src/share/vm/oops/klassKlass.cpp
@@ -68,6 +68,8 @@
   Klass* k = Klass::cast(klassOop(obj));
   // If we are alive it is valid to keep our superclass and subtype caches alive
   MarkSweep::mark_and_push(k->adr_super());
+  MarkSweep::mark_and_push(k->adr_old_version());
+  MarkSweep::mark_and_push(k->adr_new_version());
   for (juint i = 0; i < Klass::primary_super_limit(); i++)
     MarkSweep::mark_and_push(k->adr_primary_supers()+i);
   MarkSweep::mark_and_push(k->adr_secondary_super_cache());
@@ -87,6 +89,8 @@
   Klass* k = Klass::cast(klassOop(obj));
   // If we are alive it is valid to keep our superclass and subtype caches alive
   PSParallelCompact::mark_and_push(cm, k->adr_super());
+  PSParallelCompact::mark_and_push(cm, k->adr_old_version());
+  PSParallelCompact::mark_and_push(cm, k->adr_new_version());
   for (juint i = 0; i < Klass::primary_super_limit(); i++)
     PSParallelCompact::mark_and_push(cm, k->adr_primary_supers()+i);
   PSParallelCompact::mark_and_push(cm, k->adr_secondary_super_cache());
@@ -106,6 +110,8 @@
   int size = oop_size(obj);
   Klass* k = Klass::cast(klassOop(obj));
   blk->do_oop(k->adr_super());
+  blk->do_oop(k->adr_old_version());
+  blk->do_oop(k->adr_new_version());
   for (juint i = 0; i < Klass::primary_super_limit(); i++)
     blk->do_oop(k->adr_primary_supers()+i);
   blk->do_oop(k->adr_secondary_super_cache());
@@ -134,6 +140,10 @@
   oop* adr;
   adr = k->adr_super();
   if (mr.contains(adr)) blk->do_oop(adr);
+  adr = k->adr_old_version();
+  if (mr.contains(adr)) blk->do_oop(adr);
+  adr = k->adr_new_version();
+  if (mr.contains(adr)) blk->do_oop(adr);
   for (juint i = 0; i < Klass::primary_super_limit(); i++) {
     adr = k->adr_primary_supers()+i;
     if (mr.contains(adr)) blk->do_oop(adr);
@@ -147,6 +157,8 @@
   // The following are "weak links" in the perm gen and are
   // treated specially in a later phase of a perm gen collection.
   assert(oop(k)->is_perm(), "should be in perm");
+  assert(oop(k->adr_old_version())->is_perm(), "should be in perm");
+  assert(oop(k->adr_new_version())->is_perm(), "should be in perm");
   assert(oop(k->adr_subklass())->is_perm(), "should be in perm");
   assert(oop(k->adr_next_sibling())->is_perm(), "should be in perm");
   if (blk->should_remember_klasses()
@@ -167,6 +179,8 @@
   Klass* k = Klass::cast(klassOop(obj));
 
   MarkSweep::adjust_pointer(k->adr_super());
+  MarkSweep::adjust_pointer(k->adr_new_version());
+  MarkSweep::adjust_pointer(k->adr_old_version());
   for (juint i = 0; i < Klass::primary_super_limit(); i++)
     MarkSweep::adjust_pointer(k->adr_primary_supers()+i);
   MarkSweep::adjust_pointer(k->adr_secondary_super_cache());
diff --git a/src/share/vm/oops/klassOop.hpp b/src/share/vm/oops/klassOop.hpp
--- a/src/share/vm/oops/klassOop.hpp
+++ b/src/share/vm/oops/klassOop.hpp
@@ -41,8 +41,10 @@
   // returns the Klass part containing dispatching behavior
   Klass* klass_part() const                      { return (Klass*)((address)this + sizeof(klassOopDesc)); }
 
-  // Convenience wrapper
+  // Convenience wrappers
   inline oop java_mirror() const;
+  inline klassOop old_version() const;
+  inline klassOop new_version() const;
 
  private:
   // These have no implementation since klassOop should never be accessed in this fashion
diff --git a/src/share/vm/oops/klassVtable.cpp b/src/share/vm/oops/klassVtable.cpp
--- a/src/share/vm/oops/klassVtable.cpp
+++ b/src/share/vm/oops/klassVtable.cpp
@@ -97,7 +97,8 @@
     vtable_length = Universe::base_vtable_size();
   }
 
-  if (super == NULL && !Universe::is_bootstrapping() &&
+  // (tw) TODO: Check if we can relax the condition on a fixed base vtable size
+  /*if (super == NULL && !Universe::is_bootstrapping() &&
       vtable_length != Universe::base_vtable_size()) {
     // Someone is attempting to redefine java.lang.Object incorrectly.  The
     // only way this should happen is from
@@ -107,9 +108,9 @@
     vtable_length = Universe::base_vtable_size();
   }
   assert(super != NULL || vtable_length == Universe::base_vtable_size(),
-         "bad vtable size for class Object");
+         "bad vtable size for class Object");*/
   assert(vtable_length % vtableEntry::size() == 0, "bad vtable length");
-  assert(vtable_length >= Universe::base_vtable_size(), "vtable too small");
+  //assert(vtable_length >= Universe::base_vtable_size(), "vtable too small");
 }
 
 int klassVtable::index_of(methodOop m, int len) const {
@@ -1186,6 +1187,7 @@
 
 void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) {
   vtableEntry* vte = &vt->table()[index];
+  if (vte->method() == NULL || table()[index].method() == NULL) return;
   if (vte->method()->name()      != table()[index].method()->name() ||
       vte->method()->signature() != table()[index].method()->signature()) {
     fatal("mismatched name/signature of vtable entries");
@@ -1205,6 +1207,8 @@
 
 void vtableEntry::verify(klassVtable* vt, outputStream* st) {
   NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true));
+  // (tw) TODO: Check: Does not hold?
+  if (method() != NULL) {
   assert(method() != NULL, "must have set method");
   method()->verify();
   // we sub_type, because it could be a miranda method
@@ -1212,7 +1216,13 @@
 #ifndef PRODUCT
     print();
 #endif
-    fatal(err_msg("vtableEntry " PTR_FORMAT ": method is from subclass", this));
+      klassOop first_klass = vt->klass()();
+      klassOop second_klass = method()->method_holder();
+      // (tw) the following fatal does not work for old versions of classes
+      if (first_klass->klass_part()->is_newest_version()) {
+        //fatal1("vtableEntry %#lx: method is from subclass", this);
+      }
+    }
   }
 }
 
@@ -1220,7 +1230,7 @@
 
 void vtableEntry::print() {
   ResourceMark rm;
-  tty->print("vtableEntry %s: ", method()->name()->as_C_string());
+  tty->print("vtableEntry %s: ", (method() == NULL) ? "null" : method()->name()->as_C_string());
   if (Verbose) {
     tty->print("m %#lx ", (address)method());
   }
@@ -1292,7 +1302,7 @@
   for (int i = 0; i < length(); i++) {
     methodOop m = unchecked_method_at(i);
     if (m != NULL) {
-        if (m->is_old()) {
+        if (m->is_old() || !m->method_holder()->klass_part()->is_newest_version()) {
             return false;
         }
     }
diff --git a/src/share/vm/oops/methodKlass.cpp b/src/share/vm/oops/methodKlass.cpp
--- a/src/share/vm/oops/methodKlass.cpp
+++ b/src/share/vm/oops/methodKlass.cpp
@@ -93,6 +93,10 @@
   m->set_adapter_entry(NULL);
   m->clear_code(); // from_c/from_i get set to c2i/i2i
 
+  m->set_forward_method(NULL);
+  m->set_new_version(NULL);
+  m->set_old_version(NULL);
+
   if (access_flags.is_native()) {
     m->clear_native_function();
     m->set_signature_handler(NULL);
@@ -127,6 +131,9 @@
   // Performance tweak: We skip iterating over the klass pointer since we
   // know that Universe::methodKlassObj never moves.
   MarkSweep::mark_and_push(m->adr_constMethod());
+  MarkSweep::mark_and_push(m->adr_forward_method());
+  MarkSweep::mark_and_push(m->adr_new_version());
+  MarkSweep::mark_and_push(m->adr_old_version());
   MarkSweep::mark_and_push(m->adr_constants());
   if (m->method_data() != NULL) {
     MarkSweep::mark_and_push(m->adr_method_data());
@@ -141,6 +148,9 @@
   // Performance tweak: We skip iterating over the klass pointer since we
   // know that Universe::methodKlassObj never moves.
   PSParallelCompact::mark_and_push(cm, m->adr_constMethod());
+  PSParallelCompact::mark_and_push(cm, m->adr_forward_method());
+  PSParallelCompact::mark_and_push(cm, m->adr_new_version());
+  PSParallelCompact::mark_and_push(cm, m->adr_old_version());
   PSParallelCompact::mark_and_push(cm, m->adr_constants());
 #ifdef COMPILER2
   if (m->method_data() != NULL) {
@@ -159,6 +169,9 @@
   // Performance tweak: We skip iterating over the klass pointer since we
   // know that Universe::methodKlassObj never moves
   blk->do_oop(m->adr_constMethod());
+  blk->do_oop(m->adr_forward_method());
+  blk->do_oop(m->adr_new_version());
+  blk->do_oop(m->adr_old_version());
   blk->do_oop(m->adr_constants());
   if (m->method_data() != NULL) {
     blk->do_oop(m->adr_method_data());
@@ -178,6 +191,12 @@
   oop* adr;
   adr = m->adr_constMethod();
   if (mr.contains(adr)) blk->do_oop(adr);
+  adr = m->adr_new_version();
+  if (mr.contains(adr)) blk->do_oop(adr);
+  adr = m->adr_forward_method();
+  if (mr.contains(adr)) blk->do_oop(adr);
+  adr = m->adr_old_version();
+  if (mr.contains(adr)) blk->do_oop(adr);
   adr = m->adr_constants();
   if (mr.contains(adr)) blk->do_oop(adr);
   if (m->method_data() != NULL) {
@@ -197,6 +216,9 @@
   // Performance tweak: We skip iterating over the klass pointer since we
   // know that Universe::methodKlassObj never moves.
   MarkSweep::adjust_pointer(m->adr_constMethod());
+  MarkSweep::adjust_pointer(m->adr_forward_method());
+  MarkSweep::adjust_pointer(m->adr_new_version());
+  MarkSweep::adjust_pointer(m->adr_old_version());
   MarkSweep::adjust_pointer(m->adr_constants());
   if (m->method_data() != NULL) {
     MarkSweep::adjust_pointer(m->adr_method_data());
@@ -213,6 +235,9 @@
   assert(obj->is_method(), "should be method");
   methodOop m = methodOop(obj);
   PSParallelCompact::adjust_pointer(m->adr_constMethod());
+  PSParallelCompact::adjust_pointer(m->adr_forward_method());
+  PSParallelCompact::adjust_pointer(m->adr_new_version());
+  PSParallelCompact::adjust_pointer(m->adr_old_version());
   PSParallelCompact::adjust_pointer(m->adr_constants());
 #ifdef COMPILER2
   if (m->method_data() != NULL) {
@@ -234,7 +259,18 @@
   methodOop m = methodOop(obj);
   // get the effect of PrintOopAddress, always, for methods:
   st->print_cr(" - this oop:          "INTPTR_FORMAT, (intptr_t)m);
-  st->print   (" - method holder:     ");    m->method_holder()->print_value_on(st); st->cr();
+  st->print   (" - method holder:     ");    m->method_holder()->print_value_on(st);
+
+  if (m->method_holder()->klass_part()->new_version() != NULL) {
+    st->print(" (old)");
+  }
+  st->cr();
+
+  st->print_cr(" - is obsolete:       %d",   (int)(m->is_obsolete()));
+  st->print_cr(" - is old:            %d",   (int)(m->is_old()));
+  st->print_cr(" - new version:       "INTPTR_FORMAT" ",   (address)(m->new_version()));
+  st->print_cr(" - old version:       "INTPTR_FORMAT" ",   (address)(m->old_version()));
+  st->print_cr(" - holder revision:   %d", m->method_holder()->klass_part()->revision_number());
   st->print   (" - constants:         "INTPTR_FORMAT" ", (address)m->constants());
   m->constants()->print_value_on(st); st->cr();
   st->print   (" - access:            0x%x  ", m->access_flags().as_int()); m->access_flags().print_on(st); st->cr();
diff --git a/src/share/vm/oops/methodOop.cpp b/src/share/vm/oops/methodOop.cpp
--- a/src/share/vm/oops/methodOop.cpp
+++ b/src/share/vm/oops/methodOop.cpp
@@ -328,6 +328,70 @@
 }
 
 
+bool methodOopDesc::is_in_code_section(int bci) {
+  // There is no table => every bci is in the code section table.
+  if (!constMethod()->has_code_section_table()) return true;
+
+  constMethodOop m = constMethod();
+  for (int i = 0; i < m->code_section_entries(); ++i) {
+    u2 new_index = m->code_section_new_index_at(i);
+    u2 length = m->code_section_length_at(i);
+    if (bci >= new_index && bci < new_index + length) {
+      // We are in a specified code section.
+      return true;
+    }
+  }
+
+  return false;
+}
+
+int methodOopDesc::calculate_forward_bci(int bci, methodOop new_method) {
+  int original_bci = -1;
+  if (constMethod()->has_code_section_table()) {
+    assert(is_in_code_section(bci), "can only forward in section");
+    // First calculate back to original bci.
+    constMethodOop m = constMethod();
+    for (int i = 0; i < m->code_section_entries(); ++i) {
+      u2 new_index = m->code_section_new_index_at(i);
+      u2 original_index = m->code_section_original_index_at(i);
+      u2 length = m->code_section_length_at(i);
+      if (bci >= new_index && bci < new_index + length) {
+        // We are in a specified code section.
+        original_bci = bci - new_index + original_index;
+        break;
+      }
+    }
+    assert (original_bci != -1, "must have been in code section");
+  } else {
+    // No code sections specified => we are in an original method.
+    original_bci = bci;
+  }
+
+  // We know the original bci => match to new method.
+  int new_bci = -1;
+  if (new_method->constMethod()->has_code_section_table()) {
+    // Map to new bci.
+    constMethodOop m = new_method->constMethod();
+    for (int i = 0; i < m->code_section_entries(); ++i) {
+      u2 new_index = m->code_section_new_index_at(i);
+      u2 original_index = m->code_section_original_index_at(i);
+      u2 length = m->code_section_length_at(i);
+      if (original_bci >= original_index && original_bci < original_index + length) {
+        new_bci = original_bci - original_index + new_index;
+        break;
+      }
+    }
+    assert (new_bci != -1, "must have found new code section");
+
+  } else {
+    // We are in an original method.
+    new_bci = original_bci;
+  }
+
+  return new_bci;
+}
+
+
 int methodOopDesc::extra_stack_words() {
   // not an inline function, to avoid a header dependency on Interpreter
   return extra_stack_entries() * Interpreter::stackElementSize;
@@ -1079,6 +1143,9 @@
   // Reset correct method/const method, method size, and parameter info
   newcm->set_method(newm());
   newm->set_constMethod(newcm);
+  newm->set_forward_method(newm->forward_method());
+  newm->set_new_version(newm->new_version());
+  newm->set_old_version(newm->old_version());
   assert(newcm->method() == newm(), "check");
   newm->constMethod()->set_code_size(new_code_length);
   newm->constMethod()->set_constMethod_size(new_const_method_size);
diff --git a/src/share/vm/oops/methodOop.hpp b/src/share/vm/oops/methodOop.hpp
--- a/src/share/vm/oops/methodOop.hpp
+++ b/src/share/vm/oops/methodOop.hpp
@@ -116,6 +116,11 @@
   AccessFlags       _access_flags;               // Access flags
   int               _vtable_index;               // vtable index of this method (see VtableIndexFlag)
                                                  // note: can have vtables with >2**16 elements (because of inheritance)
+  // (tw) Newer version of method available?
+  methodOop         _forward_method;
+  methodOop         _new_version;
+  methodOop         _old_version;
+
 #ifdef CC_INTERP
   int               _result_index;               // C++ interpreter needs for converting results to/from stack
 #endif
@@ -174,6 +179,32 @@
   int name_index() const                         { return constMethod()->name_index();         }
   void set_name_index(int index)                 { constMethod()->set_name_index(index);       }
 
+  methodOop forward_method() const {return _forward_method; }
+  void set_forward_method(methodOop m) { _forward_method = m; }
+  bool has_forward_method() const { return forward_method() != NULL; }
+  methodOop new_version() const {return _new_version; }
+  void set_new_version(methodOop m) { _new_version = m; }
+  methodOop newest_version() { if(_new_version == NULL) return this; else return new_version()->newest_version(); }
+
+  methodOop old_version() const {return _old_version; };
+  void set_old_version(methodOop m) {
+    if (m == NULL) {
+      _old_version = NULL;
+      return;
+    }
+
+    assert(_old_version == NULL, "may only be set once");
+    assert(this->code_size() == m->code_size(), "must have same code length");
+    _old_version = m;
+  }
+
+  methodOop oldest_version() const { 
+    if(_old_version == NULL) return (methodOop)this;
+    else {
+      return old_version()->oldest_version();
+    }
+  }
+
   // signature
   Symbol* signature() const                      { return _constants->symbol_at(signature_index()); }
   int signature_index() const                    { return constMethod()->signature_index();         }
@@ -670,6 +701,10 @@
   // Inline cache support
   void cleanup_inline_caches();
 
+  // (tw) Method forwarding support.
+  bool is_in_code_section(int bci);
+  int calculate_forward_bci(int bci, methodOop new_method);
+
   // Find if klass for method is loaded
   bool is_klass_loaded_by_klass_index(int klass_index) const;
   bool is_klass_loaded(int refinfo_index, bool must_be_resolved = false) const;
@@ -723,6 +758,9 @@
 
   // Garbage collection support
   oop*  adr_constMethod() const                  { return (oop*)&_constMethod;     }
+  oop*  adr_forward_method() const               { return (oop*)&_forward_method;  }
+  oop*  adr_new_version() const                  { return (oop*)&_new_version;     }
+  oop*  adr_old_version() const                  { return (oop*)&_old_version;     }
   oop*  adr_constants() const                    { return (oop*)&_constants;       }
   oop*  adr_method_data() const                  { return (oop*)&_method_data;     }
 };
diff --git a/src/share/vm/oops/oop.hpp b/src/share/vm/oops/oop.hpp
--- a/src/share/vm/oops/oop.hpp
+++ b/src/share/vm/oops/oop.hpp
@@ -94,6 +94,7 @@
   narrowOop* compressed_klass_addr();
 
   void set_klass(klassOop k);
+  void set_klass_no_check(klassOop k);
 
   // For klass field compression
   int klass_gap() const;
@@ -134,6 +135,7 @@
   bool is_array()              const;
   bool is_objArray()           const;
   bool is_klass()              const;
+  bool is_instanceKlass()      const;
   bool is_thread()             const;
   bool is_method()             const;
   bool is_constMethod()        const;
diff --git a/src/share/vm/oops/oop.inline.hpp b/src/share/vm/oops/oop.inline.hpp
--- a/src/share/vm/oops/oop.inline.hpp
+++ b/src/share/vm/oops/oop.inline.hpp
@@ -115,6 +115,14 @@
   }
 }
 
+inline void oopDesc::set_klass_no_check(klassOop k) {
+  if (UseCompressedOops) {
+    oop_store_without_check(compressed_klass_addr(), (oop)k);
+  } else {
+    oop_store_without_check(klass_addr(), (oop) k);
+  }
+}
+
 inline int oopDesc::klass_gap() const {
   return *(int*)(((intptr_t)this) + klass_gap_offset_in_bytes());
 }
@@ -148,6 +156,7 @@
 inline bool oopDesc::is_typeArray()          const { return blueprint()->oop_is_typeArray(); }
 inline bool oopDesc::is_javaArray()          const { return blueprint()->oop_is_javaArray(); }
 inline bool oopDesc::is_klass()              const { return blueprint()->oop_is_klass(); }
+inline bool oopDesc::is_instanceKlass()      const { return blueprint()->oop_is_instanceKlass(); }
 inline bool oopDesc::is_thread()             const { return blueprint()->oop_is_thread(); }
 inline bool oopDesc::is_method()             const { return blueprint()->oop_is_method(); }
 inline bool oopDesc::is_constMethod()        const { return blueprint()->oop_is_constMethod(); }
diff --git a/src/share/vm/prims/jni.cpp b/src/share/vm/prims/jni.cpp
--- a/src/share/vm/prims/jni.cpp
+++ b/src/share/vm/prims/jni.cpp
@@ -405,7 +405,7 @@
     }
   }
   klassOop k = SystemDictionary::resolve_from_stream(class_name, class_loader,
-                                                     Handle(), &st, true,
+                                                     Handle(), &st, true, KlassHandle(),
                                                      CHECK_NULL);
 
   if (TraceClassResolution && k != NULL) {
diff --git a/src/share/vm/prims/jvm.cpp b/src/share/vm/prims/jvm.cpp
--- a/src/share/vm/prims/jvm.cpp
+++ b/src/share/vm/prims/jvm.cpp
@@ -866,7 +866,7 @@
   Handle protection_domain (THREAD, JNIHandles::resolve(pd));
   klassOop k = SystemDictionary::resolve_from_stream(class_name, class_loader,
                                                      protection_domain, &st,
-                                                     verify != 0,
+                                                     verify != 0, KlassHandle(),
                                                      CHECK_NULL);
 
   if (TraceClassResolution && k != NULL) {
diff --git a/src/share/vm/prims/jvmtiEnv.cpp b/src/share/vm/prims/jvmtiEnv.cpp
--- a/src/share/vm/prims/jvmtiEnv.cpp
+++ b/src/share/vm/prims/jvmtiEnv.cpp
@@ -290,7 +290,10 @@
     class_definitions[index].klass              = jcls;
   }
   VM_RedefineClasses op(class_count, class_definitions, jvmti_class_load_kind_retransform);
-  VMThread::execute(&op);
+  {
+    MutexLocker sd_mutex(RedefineClasses_lock);
+    VMThread::execute(&op);
+  }
   return (op.check_error());
 } /* end RetransformClasses */
 
@@ -299,9 +302,12 @@
 // class_definitions - pre-checked for NULL
 jvmtiError
 JvmtiEnv::RedefineClasses(jint class_count, const jvmtiClassDefinition* class_definitions) {
-//TODO: add locking
+
   VM_RedefineClasses op(class_count, class_definitions, jvmti_class_load_kind_redefine);
-  VMThread::execute(&op);
+  {
+    MutexLocker sd_mutex(RedefineClasses_lock);
+    VMThread::execute(&op);
+  }
   return (op.check_error());
 } /* end RedefineClasses */
 
diff --git a/src/share/vm/prims/jvmtiExport.cpp b/src/share/vm/prims/jvmtiExport.cpp
--- a/src/share/vm/prims/jvmtiExport.cpp
+++ b/src/share/vm/prims/jvmtiExport.cpp
@@ -2307,7 +2307,7 @@
 // iterate over any code blob descriptors collected and post a
 // DYNAMIC_CODE_GENERATED event to the profiler.
 JvmtiDynamicCodeEventCollector::~JvmtiDynamicCodeEventCollector() {
-  assert(!JavaThread::current()->owns_locks(), "all locks must be released to post deferred events");
+  assert(!JavaThread::current()->owns_locks_but_redefine_classes_lock(), "all locks must be released to post deferred events");
  // iterate over any code blob descriptors that we collected
  if (_code_blobs != NULL) {
    for (int i=0; i<_code_blobs->length(); i++) {
diff --git a/src/share/vm/prims/jvmtiImpl.cpp b/src/share/vm/prims/jvmtiImpl.cpp
--- a/src/share/vm/prims/jvmtiImpl.cpp
+++ b/src/share/vm/prims/jvmtiImpl.cpp
@@ -286,6 +286,8 @@
 void JvmtiBreakpoint::each_method_version_do(method_action meth_act) {
   ((methodOopDesc*)_method->*meth_act)(_bci);
 
+  // DCEVM: TODO: Check how we can implement this differently here!
+
   // add/remove breakpoint to/from versions of the method that
   // are EMCP. Directly or transitively obsolete methods are
   // not saved in the PreviousVersionInfo.
diff --git a/src/share/vm/prims/jvmtiRedefineClasses.cpp b/src/share/vm/prims/jvmtiRedefineClasses.cpp
--- a/src/share/vm/prims/jvmtiRedefineClasses.cpp
+++ b/src/share/vm/prims/jvmtiRedefineClasses.cpp
@@ -30,491 +30,637 @@
 #include "interpreter/rewriter.hpp"
 #include "memory/gcLocker.hpp"
 #include "memory/universe.inline.hpp"
+#include "memory/cardTableRS.hpp"
+#include "oops/klassVtable.hpp"
 #include "oops/fieldStreams.hpp"
-#include "oops/klassVtable.hpp"
 #include "prims/jvmtiImpl.hpp"
 #include "prims/jvmtiRedefineClasses.hpp"
+#include "prims/jvmtiClassFileReconstituter.hpp"
 #include "prims/methodComparator.hpp"
 #include "runtime/deoptimization.hpp"
 #include "runtime/relocator.hpp"
 #include "utilities/bitMap.inline.hpp"
+#include "compiler/compileBroker.hpp"
 
 
 objArrayOop VM_RedefineClasses::_old_methods = NULL;
 objArrayOop VM_RedefineClasses::_new_methods = NULL;
-methodOop*  VM_RedefineClasses::_matching_old_methods = NULL;
-methodOop*  VM_RedefineClasses::_matching_new_methods = NULL;
-methodOop*  VM_RedefineClasses::_deleted_methods      = NULL;
-methodOop*  VM_RedefineClasses::_added_methods        = NULL;
+int*        VM_RedefineClasses::_matching_old_methods = NULL;
+int*        VM_RedefineClasses::_matching_new_methods = NULL;
+int*        VM_RedefineClasses::_deleted_methods      = NULL;
+int*        VM_RedefineClasses::_added_methods        = NULL;
 int         VM_RedefineClasses::_matching_methods_length = 0;
 int         VM_RedefineClasses::_deleted_methods_length  = 0;
 int         VM_RedefineClasses::_added_methods_length    = 0;
 klassOop    VM_RedefineClasses::_the_class_oop = NULL;
 
-
-VM_RedefineClasses::VM_RedefineClasses(jint class_count,
-                                       const jvmtiClassDefinition *class_defs,
-                                       JvmtiClassLoadKind class_load_kind) {
+// Holds the revision number of the current class redefinition
+int    VM_RedefineClasses::_revision_number = -1;
+
+VM_RedefineClasses::VM_RedefineClasses(jint class_count, const jvmtiClassDefinition *class_defs, JvmtiClassLoadKind class_load_kind)
+   : VM_GC_Operation(Universe::heap()->total_full_collections(), GCCause::_jvmti_force_gc) {
+  RC_TIMER_START(_timer_total);
   _class_count = class_count;
   _class_defs = class_defs;
   _class_load_kind = class_load_kind;
-  _res = JVMTI_ERROR_NONE;
+  _updated_oops = NULL;
+  _result = JVMTI_ERROR_NONE;
 }
 
+VM_RedefineClasses::~VM_RedefineClasses() {
+  {
+    MonitorLockerEx ml(RedefinitionSync_lock);
+    Threads::set_wait_at_instrumentation_entry(false);
+    ml.notify_all();
+  }
+
+  unlock_threads();
+  RC_TIMER_STOP(_timer_total);
+
+  if (TimeRedefineClasses) {
+    tty->print_cr("Timing Prologue:             %d", _timer_prologue.milliseconds());
+    tty->print_cr("Timing Class Loading:        %d", _timer_class_loading.milliseconds());
+    tty->print_cr("Timing Waiting for Lock:     %d", _timer_wait_for_locks.milliseconds());
+    tty->print_cr("Timing Class Linking:        %d", _timer_class_linking.milliseconds());
+    tty->print_cr("Timing Check Type:           %d", _timer_check_type.milliseconds());
+    tty->print_cr("Timing Prepare Redefinition: %d", _timer_prepare_redefinition.milliseconds());
+    tty->print_cr("Timing Redefinition GC:      %d", _timer_redefinition.milliseconds());
+    tty->print_cr("Timing Epilogue:             %d", _timer_vm_op_epilogue.milliseconds());
+    tty->print_cr("------------------------------------------------------------------");
+    tty->print_cr("Total Time:                  %d", _timer_total.milliseconds());
+  }
+}
+
+// Searches for all affected classes and performs a sorting such that a supertype is always before a subtype.
+jvmtiError VM_RedefineClasses::find_sorted_affected_classes(GrowableArray<instanceKlassHandle> *all_affected_klasses) {
+
+  // Create array with all classes for which the redefine command was given
+  GrowableArray<instanceKlassHandle> klasses_to_redefine;
+  for (int i=0; i<_class_count; i++) {
+    oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
+    instanceKlassHandle klass_handle(Thread::current(), java_lang_Class::as_klassOop(mirror));
+    klasses_to_redefine.append(klass_handle);
+    assert(klass_handle->new_version() == NULL, "Must be new class");
+  }
+
+  // Find classes not directly redefined, but affected by a redefinition (because one of its supertypes is redefined)
+  GrowableArray<instanceKlassHandle> affected_classes;
+  FindAffectedKlassesClosure closure(&klasses_to_redefine, &affected_classes);
+
+  // Trace affected classes
+  if (RC_TRACE_ENABLED(0x00000001)) {
+    RC_TRACE(0x00000001, ("Klasses affected: %d",
+      affected_classes.length()));
+    for (int i=0; i<affected_classes.length(); i++) {
+      RC_TRACE(0x00000001, ("%s",
+        affected_classes.at(i)->name()->as_C_string()));
+    }
+  }
+
+  // Add the array of affected classes and the array of redefined classes to get a list of all classes that need a redefinition
+  all_affected_klasses->appendAll(&klasses_to_redefine);
+  all_affected_klasses->appendAll(&affected_classes);
+
+  // Sort the affected klasses such that a supertype is always on a smaller array index than its subtype.
+  jvmtiError result = do_topological_class_sorting(_class_defs, _class_count, &affected_classes, all_affected_klasses, Thread::current());
+  if (RC_TRACE_ENABLED(0x00000001)) {
+    RC_TRACE(0x00000001, ("Redefine order: "));
+    for (int i=0; i<all_affected_klasses->length(); i++) {
+      RC_TRACE(0x00000001, ("%s",
+        all_affected_klasses->at(i)->name()->as_C_string()));
+    }
+  }
+
+  return result;
+}
+
+// Searches for the class bytes of the given class and returns them as a byte array.
+jvmtiError VM_RedefineClasses::find_class_bytes(instanceKlassHandle the_class, const unsigned char **class_bytes, jint *class_byte_count, jboolean *not_changed) {
+
+  *not_changed = false;
+
+  // Search for the index in the redefinition array that corresponds to the current class
+  int j;
+  for (j=0; j<_class_count; j++) {
+    oop mirror = JNIHandles::resolve_non_null(_class_defs[j].klass);
+    klassOop the_class_oop = java_lang_Class::as_klassOop(mirror);
+    if (the_class_oop == the_class()) {
+      break;
+    }
+  }
+
+  if (j == _class_count) {
+
+    *not_changed = true;
+
+    // Redefine with same bytecodes. This is a class that is only indirectly affected by redefinition,
+    // so the user did not specify a different bytecode for that class.
+
+    if (the_class->get_cached_class_file_bytes() == NULL) {
+      // not cached, we need to reconstitute the class file from VM representation
+      constantPoolHandle  constants(Thread::current(), the_class->constants());
+      ObjectLocker ol(constants, Thread::current());    // lock constant pool while we query it
+
+      JvmtiClassFileReconstituter reconstituter(the_class);
+      if (reconstituter.get_error() != JVMTI_ERROR_NONE) {
+        return reconstituter.get_error();
+      }
+
+      *class_byte_count = (jint)reconstituter.class_file_size();
+      *class_bytes      = (unsigned char*)reconstituter.class_file_bytes();
+
+    } else {
+
+      // it is cached, get it from the cache
+      *class_byte_count = the_class->get_cached_class_file_len();
+      *class_bytes      = the_class->get_cached_class_file_bytes();
+    }
+
+  } else {
+
+    // Redefine with bytecodes at index j
+    *class_bytes = _class_defs[j].class_bytes;
+    *class_byte_count = _class_defs[j].class_byte_count;
+  }
+
+  return JVMTI_ERROR_NONE;
+}
+
+// Prologue of the VM operation, called on the Java thread in parallel to normal program execution
 bool VM_RedefineClasses::doit_prologue() {
-  if (_class_count == 0) {
-    _res = JVMTI_ERROR_NONE;
+
+  _revision_number++;
+  RC_TRACE(0x00000001, ("Redefinition with revision number %d started!", _revision_number));
+
+  assert(Thread::current()->is_Java_thread(), "must be Java thread");
+  RC_TIMER_START(_timer_prologue);
+
+  if (!check_arguments()) {
+    RC_TIMER_STOP(_timer_prologue);
     return false;
   }
-  if (_class_defs == NULL) {
-    _res = JVMTI_ERROR_NULL_POINTER;
+
+  // We first load new class versions in the prologue, because somewhere down the
+  // call chain it is required that the current thread is a Java thread.
+  _new_classes = new (ResourceObj::C_HEAP) GrowableArray<instanceKlassHandle>(5, true);
+  _result = load_new_class_versions(Thread::current());
+
+  RC_TRACE(0x00000001, ("Loaded new class versions!"));
+  if (_result != JVMTI_ERROR_NONE) {
+    RC_TRACE(0x00000001, ("error occured: %d!", _result));
+    delete _new_classes;
+    _new_classes = NULL;
+    RC_TIMER_STOP(_timer_prologue);
     return false;
   }
+
+  RC_TRACE(0x00000001, ("nearly finished"));
+  VM_GC_Operation::doit_prologue();
+  RC_TIMER_STOP(_timer_prologue);
+  RC_TRACE(0x00000001, ("doit_prologue finished!"));
+  return true;
+}
+
+// Checks basic properties of the arguments of the redefinition command.
+bool VM_RedefineClasses::check_arguments() {
+
+  if (_class_count == 0) RC_ABORT(JVMTI_ERROR_NONE);
+  if (_class_defs == NULL) RC_ABORT(JVMTI_ERROR_NULL_POINTER);
   for (int i = 0; i < _class_count; i++) {
-    if (_class_defs[i].klass == NULL) {
-      _res = JVMTI_ERROR_INVALID_CLASS;
-      return false;
+    if (_class_defs[i].klass == NULL) RC_ABORT(JVMTI_ERROR_INVALID_CLASS);
+    if (_class_defs[i].class_byte_count == 0) RC_ABORT(JVMTI_ERROR_INVALID_CLASS_FORMAT);
+    if (_class_defs[i].class_bytes == NULL) RC_ABORT(JVMTI_ERROR_NULL_POINTER);
+  }
+
+  return true;
+}
+
+jvmtiError VM_RedefineClasses::check_exception() const {
+  Thread* THREAD = Thread::current();
+  if (HAS_PENDING_EXCEPTION) {
+
+    Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
+    RC_TRACE(0x00000001, ("parse_stream exception: '%s'",
+      ex_name->as_C_string()));
+    if (TraceRedefineClasses >= 1) {
+      java_lang_Throwable::print(PENDING_EXCEPTION, tty);
+      tty->print_cr("");
     }
-    if (_class_defs[i].class_byte_count == 0) {
-      _res = JVMTI_ERROR_INVALID_CLASS_FORMAT;
-      return false;
-    }
-    if (_class_defs[i].class_bytes == NULL) {
-      _res = JVMTI_ERROR_NULL_POINTER;
-      return false;
+    CLEAR_PENDING_EXCEPTION;
+
+    if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
+      return JVMTI_ERROR_UNSUPPORTED_VERSION;
+    } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
+      return JVMTI_ERROR_INVALID_CLASS_FORMAT;
+    } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
+      return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
+    } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
+      // The message will be "XXX (wrong name: YYY)"
+      return JVMTI_ERROR_NAMES_DONT_MATCH;
+    } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
+      return JVMTI_ERROR_OUT_OF_MEMORY;
+    } else {
+      // Just in case more exceptions can be thrown..
+      return JVMTI_ERROR_FAILS_VERIFICATION;
     }
   }
 
-  // Start timer after all the sanity checks; not quite accurate, but
-  // better than adding a bunch of stop() calls.
-  RC_TIMER_START(_timer_vm_op_prologue);
-
-  // We first load new class versions in the prologue, because somewhere down the
-  // call chain it is required that the current thread is a Java thread.
-  _res = load_new_class_versions(Thread::current());
-  if (_res != JVMTI_ERROR_NONE) {
-    // Free os::malloc allocated memory in load_new_class_version.
-    os::free(_scratch_classes);
-    RC_TIMER_STOP(_timer_vm_op_prologue);
-    return false;
+  return JVMTI_ERROR_NONE;
+}
+
+// Loads all new class versions and stores the instanceKlass handles in an array.
+jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) {
+
+  ResourceMark rm(THREAD);
+
+  RC_TRACE(0x00000001, ("==================================================================="));
+  RC_TRACE(0x00000001, ("load new class versions (%d)",
+    _class_count));
+
+  // Retrieve an array of all classes that need to be redefined
+  GrowableArray<instanceKlassHandle> all_affected_klasses;
+  jvmtiError err = find_sorted_affected_classes(&all_affected_klasses);
+  if (err != JVMTI_ERROR_NONE) {
+    RC_TRACE(0x00000001, ("Error finding sorted affected classes: %d",
+      (int)err));
+    return err;
   }
 
-  RC_TIMER_STOP(_timer_vm_op_prologue);
-  return true;
-}
-
-void VM_RedefineClasses::doit() {
-  Thread *thread = Thread::current();
-
-  if (UseSharedSpaces) {
-    // Sharing is enabled so we remap the shared readonly space to
-    // shared readwrite, private just in case we need to redefine
-    // a shared class. We do the remap during the doit() phase of
-    // the safepoint to be safer.
-    if (!CompactingPermGenGen::remap_shared_readonly_as_readwrite()) {
-      RC_TRACE_WITH_THREAD(0x00000001, thread,
-        ("failed to remap shared readonly space to readwrite, private"));
-      _res = JVMTI_ERROR_INTERNAL;
-      return;
+
+  JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
+
+  _max_redefinition_flags = Klass::NoRedefinition;
+  jvmtiError result = JVMTI_ERROR_NONE;
+
+  for (int i=0; i<all_affected_klasses.length(); i++) {
+    RC_TRACE(0x00000002, ("Processing affected class %d of %d",
+      i+1, all_affected_klasses.length()));
+
+    instanceKlassHandle the_class = all_affected_klasses.at(i);
+    RC_TRACE(0x00000002, ("name=%s",
+      the_class->name()->as_C_string()));
+
+    the_class->link_class(THREAD);
+    result = check_exception();
+    if (result != JVMTI_ERROR_NONE) break;
+
+    // Find new class bytes
+    const unsigned char* class_bytes;
+    jint class_byte_count;
+    jvmtiError error;
+    jboolean not_changed;
+    if ((error = find_class_bytes(the_class, &class_bytes, &class_byte_count, &not_changed)) != JVMTI_ERROR_NONE) {
+      RC_TRACE(0x00000001, ("Error finding class bytes: %d",
+        (int)error));
+      result = error;
+      break;
+    }
+    assert(class_bytes != NULL && class_byte_count != 0, "Class bytes defined at this point!");
+
+
+    // Set redefined class handle in JvmtiThreadState class.
+    // This redefined class is sent to agent event handler for class file
+    // load hook event.
+    state->set_class_being_redefined(&the_class, _class_load_kind);
+
+    RC_TRACE(0x00000002, ("Before resolving from stream"));
+
+    RC_TIMER_STOP(_timer_prologue);
+    RC_TIMER_START(_timer_class_loading);
+
+
+    // Parse the stream.
+    Handle the_class_loader(THREAD, the_class->class_loader());
+    Handle protection_domain(THREAD, the_class->protection_domain());
+    Symbol* the_class_sym = the_class->name();
+    ClassFileStream st((u1*) class_bytes, class_byte_count, (char *)"__VM_RedefineClasses__");
+    instanceKlassHandle new_class(THREAD, SystemDictionary::resolve_from_stream(the_class_sym,
+      the_class_loader,
+      protection_domain,
+      &st,
+      true,
+      the_class,
+      THREAD));
+
+    not_changed = false;
+
+    RC_TIMER_STOP(_timer_class_loading);
+    RC_TIMER_START(_timer_prologue);
+
+    RC_TRACE(0x00000002, ("After resolving class from stream!"));
+    // Clear class_being_redefined just to be sure.
+    state->clear_class_being_redefined();
+
+    result = check_exception();
+    if (result != JVMTI_ERROR_NONE) break;
+
+#ifdef ASSERT
+
+    assert(new_class() != NULL, "Class could not be loaded!");
+    assert(new_class() != the_class(), "must be different");
+    assert(new_class->new_version() == NULL && new_class->old_version() != NULL, "");
+
+
+    objArrayOop k_interfaces = new_class->local_interfaces();
+    for (int j=0; j<k_interfaces->length(); j++) {
+      assert(((klassOop)k_interfaces->obj_at(j))->klass_part()->is_newest_version(), "just checking");
+    }
+
+    if (!THREAD->is_Compiler_thread()) {
+
+      RC_TRACE(0x00000002, ("name=%s loader="INTPTR_FORMAT" protection_domain="INTPTR_FORMAT" ",
+        the_class->name()->as_C_string(),
+        (address)(the_class->class_loader()),
+        (address)(the_class->protection_domain())));
+      // If we are on the compiler thread, we must not try to resolve a class.
+      klassOop systemLookup = SystemDictionary::resolve_or_null(the_class->name(), the_class->class_loader(), the_class->protection_domain(), THREAD);
+      
+      if (systemLookup != NULL) {
+        assert(systemLookup == new_class->old_version(), "Old class must be in system dictionary!");
+      
+
+        Klass *subklass = new_class()->klass_part()->subklass();
+        while (subklass != NULL) {
+          assert(subklass->new_version() == NULL, "Most recent version of class!");
+          subklass = subklass->next_sibling();
+        }
+      } else {
+        // This can happen for reflection generated classes.. ?
+        CLEAR_PENDING_EXCEPTION;
+      }
+    }
+
+#endif
+
+    if (RC_TRACE_ENABLED(0x00000001)) {
+      if (new_class->layout_helper() != the_class->layout_helper()) {
+        RC_TRACE(0x00000001, ("Instance size change for class %s: new=%d old=%d",
+         new_class->name()->as_C_string(),
+         new_class->layout_helper(),
+         the_class->layout_helper()));
+      }
+    }
+
+    // Set the new version of the class
+    new_class->set_revision_number(_revision_number);
+    new_class->set_redefinition_index(i);
+    the_class->set_new_version(new_class());
+    _new_classes->append(new_class);
+
+    assert(new_class->new_version() == NULL, "");
+
+    int redefinition_flags = Klass::NoRedefinition;
+
+    if (not_changed) {
+      redefinition_flags = Klass::NoRedefinition;
+    } else if (AllowAdvancedClassRedefinition) {
+      redefinition_flags = calculate_redefinition_flags(new_class);
+    } else {
+      jvmtiError allowed = check_redefinition_allowed(new_class);
+      if (allowed != JVMTI_ERROR_NONE) {
+        RC_TRACE(0x00000001, ("Error redefinition not allowed!"));
+        result = allowed;
+        break;
+      }
+      redefinition_flags = Klass::ModifyClass;
+    }
+
+    if (new_class->super() != NULL) {
+      redefinition_flags = redefinition_flags | new_class->super()->klass_part()->redefinition_flags();
+    }
+
+    for (int j=0; j<new_class->local_interfaces()->length(); j++) {
+      redefinition_flags = redefinition_flags | ((klassOop)new_class->local_interfaces()->obj_at(j))->klass_part()->redefinition_flags();
+    }
+
+    new_class->set_redefinition_flags(redefinition_flags);
+
+    _max_redefinition_flags = _max_redefinition_flags | redefinition_flags;
+
+    if ((redefinition_flags & Klass::ModifyInstances) != 0) {
+      // TODO: Check if watch access flags of static fields are updated correctly.
+      calculate_instance_update_information(_new_classes->at(i)());
+    } else {
+      assert(new_class->layout_helper() >> 1 == new_class->old_version()->klass_part()->layout_helper() >> 1, "must be equal");
+      assert(new_class->fields()->length() == ((instanceKlass*)new_class->old_version()->klass_part())->fields()->length(), "must be equal");
+
+      fieldDescriptor fd_new;
+      fieldDescriptor fd_old;
+      for (JavaFieldStream fs(new_class); !fs.done(); fs.next()) {
+        fd_new.initialize(new_class(), fs.index());
+        fd_old.initialize(new_class->old_version(), fs.index());
+        transfer_special_access_flags(&fd_old, &fd_new);
+      }
+    }
+
+    if (RC_TRACE_ENABLED(0x00000008)) {
+      if (new_class->super() != NULL) {
+        RC_TRACE(0x00000008, ("Super class is %s",
+          new_class->super()->klass_part()->name()->as_C_string()));
+      }
+    }
+
+#ifdef ASSERT
+    assert(new_class->super() == NULL || new_class->super()->klass_part()->new_version() == NULL, "Super klass must be newest version!");
+
+    the_class->vtable()->verify(tty);
+    new_class->vtable()->verify(tty);
+#endif
+
+    RC_TRACE(0x00000002, ("Verification done!"));
+
+    if (i == all_affected_klasses.length() - 1) {
+
+      // This was the last class processed => check if additional classes have been loaded in the meantime
+
+      RC_TIMER_STOP(_timer_prologue);
+      lock_threads();
+      RC_TIMER_START(_timer_prologue);
+
+      for (int j=0; j<all_affected_klasses.length(); j++) {
+
+        klassOop initial_klass = all_affected_klasses.at(j)();
+        Klass *initial_subklass = initial_klass->klass_part()->subklass();
+        Klass *cur_klass = initial_subklass;
+        while(cur_klass != NULL) {
+
+          if(cur_klass->oop_is_instance() && cur_klass->is_newest_version()) {
+            instanceKlassHandle handle(THREAD, cur_klass->as_klassOop());
+            if (!all_affected_klasses.contains(handle)) {
+
+              int k = i + 1;
+              for (; k<all_affected_klasses.length(); k++) {
+                if (all_affected_klasses.at(k)->is_subtype_of(cur_klass->as_klassOop())) {
+                  break;
+                }
+              }
+              all_affected_klasses.insert_before(k, handle);
+              RC_TRACE(0x00000002, ("Adding newly loaded class to affected classes: %s",
+                cur_klass->name()->as_C_string()));
+            }
+          }
+
+          cur_klass = cur_klass->next_sibling();
+        }
+      }
+
+      int new_count = all_affected_klasses.length() - 1 - i;
+      if (new_count != 0) {
+
+        unlock_threads();
+        RC_TRACE(0x00000001, ("Found new number of affected classes: %d",
+          new_count));
+      }
     }
   }
 
-  for (int i = 0; i < _class_count; i++) {
-    redefine_single_class(_class_defs[i].klass, _scratch_classes[i], thread);
+  if (result != JVMTI_ERROR_NONE) {
+    rollback();
+    return result;
   }
-  // Disable any dependent concurrent compilations
-  SystemDictionary::notice_modification();
-
-  // Set flag indicating that some invariants are no longer true.
-  // See jvmtiExport.hpp for detailed explanation.
-  JvmtiExport::set_has_redefined_a_class();
+
+  RC_TIMER_STOP(_timer_prologue);
+  RC_TIMER_START(_timer_class_linking);
+  // Link and verify new classes _after_ all classes have been updated in the system dictionary!
+  for (int i=0; i<all_affected_klasses.length(); i++) {
+    instanceKlassHandle the_class = all_affected_klasses.at(i);
+    instanceKlassHandle new_class(the_class->new_version());
+
+    RC_TRACE(0x00000002, ("Linking class %d/%d %s",
+      i,
+      all_affected_klasses.length(),
+      the_class->name()->as_C_string()));
+    new_class->link_class(THREAD);
+
+    result = check_exception();
+    if (result != JVMTI_ERROR_NONE) break;
+  }
+  RC_TIMER_STOP(_timer_class_linking);
+  RC_TIMER_START(_timer_prologue);
+
+  if (result != JVMTI_ERROR_NONE) {
+    rollback();
+    return result;
+  }
+
+  RC_TRACE(0x00000002, ("All classes loaded!"));
 
 #ifdef ASSERT
-  SystemDictionary::classes_do(check_class, thread);
+  for (int i=0; i<all_affected_klasses.length(); i++) {
+    instanceKlassHandle the_class = all_affected_klasses.at(i);
+    assert(the_class->new_version() != NULL, "Must have been redefined");
+    instanceKlassHandle new_version = instanceKlassHandle(THREAD, the_class->new_version());
+    assert(new_version->new_version() == NULL, "Must be newest version");
+
+    if (!(new_version->super() == NULL || new_version->super()->klass_part()->new_version() == NULL)) {
+      new_version()->print();
+      new_version->super()->print();
+    }
+    assert(new_version->super() == NULL || new_version->super()->klass_part()->new_version() == NULL, "Super class must be newest version");
+  }
+
+  SystemDictionary::classes_do(check_class, THREAD);
+
 #endif
+
+  RC_TRACE(0x00000001, ("Finished verification!"));
+  return JVMTI_ERROR_NONE;
 }
 
-void VM_RedefineClasses::doit_epilogue() {
-  // Free os::malloc allocated memory.
-  // The memory allocated in redefine will be free'ed in next VM operation.
-  os::free(_scratch_classes);
-
-  if (RC_TRACE_ENABLED(0x00000004)) {
-    // Used to have separate timers for "doit" and "all", but the timer
-    // overhead skewed the measurements.
-    jlong doit_time = _timer_rsc_phase1.milliseconds() +
-                      _timer_rsc_phase2.milliseconds();
-    jlong all_time = _timer_vm_op_prologue.milliseconds() + doit_time;
-
-    RC_TRACE(0x00000004, ("vm_op: all=" UINT64_FORMAT
-      "  prologue=" UINT64_FORMAT "  doit=" UINT64_FORMAT, all_time,
-      _timer_vm_op_prologue.milliseconds(), doit_time));
-    RC_TRACE(0x00000004,
-      ("redefine_single_class: phase1=" UINT64_FORMAT "  phase2=" UINT64_FORMAT,
-       _timer_rsc_phase1.milliseconds(), _timer_rsc_phase2.milliseconds()));
+void VM_RedefineClasses::lock_threads() {
+
+  RC_TIMER_START(_timer_wait_for_locks);
+
+
+  JavaThread *javaThread = Threads::first();
+  while (javaThread != NULL) {
+    if (javaThread->is_Compiler_thread() && javaThread != Thread::current()) {
+      CompilerThread *compilerThread = (CompilerThread *)javaThread;
+      compilerThread->set_should_bailout(true);
+    }
+    javaThread = javaThread->next();
   }
+
+  int cnt = 0;
+  javaThread = Threads::first();
+  while (javaThread != NULL) {
+    if (javaThread->is_Compiler_thread() && javaThread != Thread::current()) {
+      CompilerThread *compilerThread = (CompilerThread *)javaThread;
+      compilerThread->compilation_mutex()->lock();
+      cnt++;
+    }
+    javaThread = javaThread->next();
+  }
+
+  RC_TRACE(0x00000002, ("Locked %d compiler threads", cnt));
+
+  cnt = 0;
+  javaThread = Threads::first();
+  while (javaThread != NULL) {
+    if (javaThread != Thread::current()) {
+      javaThread->redefine_classes_mutex()->lock();
+    }
+    javaThread = javaThread->next();
+  }
+
+
+  RC_TRACE(0x00000002, ("Locked %d threads", cnt));
+
+  RC_TIMER_STOP(_timer_wait_for_locks);
 }
 
-bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
-  // classes for primitives cannot be redefined
-  if (java_lang_Class::is_primitive(klass_mirror)) {
-    return false;
+void VM_RedefineClasses::unlock_threads() {
+
+  int cnt = 0;
+  JavaThread *javaThread = Threads::first();
+  Thread *thread = Thread::current();
+  while (javaThread != NULL) {
+    if (javaThread->is_Compiler_thread() && javaThread != Thread::current()) {
+      CompilerThread *compilerThread = (CompilerThread *)javaThread;
+      if (compilerThread->compilation_mutex()->owned_by_self()) {
+        compilerThread->compilation_mutex()->unlock();
+        cnt++;
+      }
+    }
+    javaThread = javaThread->next();
   }
-  klassOop the_class_oop = java_lang_Class::as_klassOop(klass_mirror);
-  // classes for arrays cannot be redefined
-  if (the_class_oop == NULL || !Klass::cast(the_class_oop)->oop_is_instance()) {
-    return false;
+
+  RC_TRACE(0x00000002, ("Unlocked %d compiler threads", cnt));
+
+  cnt = 0;
+  javaThread = Threads::first();
+  while (javaThread != NULL) {
+    if (javaThread != Thread::current()) {
+      if (javaThread->redefine_classes_mutex()->owned_by_self()) {
+        javaThread->redefine_classes_mutex()->unlock();
+      }
+    }
+    javaThread = javaThread->next();
   }
-  return true;
+
+  RC_TRACE(0x00000002, ("Unlocked %d threads", cnt));
 }
 
-// Append the current entry at scratch_i in scratch_cp to *merge_cp_p
-// where the end of *merge_cp_p is specified by *merge_cp_length_p. For
-// direct CP entries, there is just the current entry to append. For
-// indirect and double-indirect CP entries, there are zero or more
-// referenced CP entries along with the current entry to append.
-// Indirect and double-indirect CP entries are handled by recursive
-// calls to append_entry() as needed. The referenced CP entries are
-// always appended to *merge_cp_p before the referee CP entry. These
-// referenced CP entries may already exist in *merge_cp_p in which case
-// there is nothing extra to append and only the current entry is
-// appended.
-void VM_RedefineClasses::append_entry(constantPoolHandle scratch_cp,
-       int scratch_i, constantPoolHandle *merge_cp_p, int *merge_cp_length_p,
-       TRAPS) {
-
-  // append is different depending on entry tag type
-  switch (scratch_cp->tag_at(scratch_i).value()) {
-
-    // The old verifier is implemented outside the VM. It loads classes,
-    // but does not resolve constant pool entries directly so we never
-    // see Class entries here with the old verifier. Similarly the old
-    // verifier does not like Class entries in the input constant pool.
-    // The split-verifier is implemented in the VM so it can optionally
-    // and directly resolve constant pool entries to load classes. The
-    // split-verifier can accept either Class entries or UnresolvedClass
-    // entries in the input constant pool. We revert the appended copy
-    // back to UnresolvedClass so that either verifier will be happy
-    // with the constant pool entry.
-    case JVM_CONSTANT_Class:
-    {
-      // revert the copy to JVM_CONSTANT_UnresolvedClass
-      (*merge_cp_p)->unresolved_klass_at_put(*merge_cp_length_p,
-        scratch_cp->klass_name_at(scratch_i));
-
-      if (scratch_i != *merge_cp_length_p) {
-        // The new entry in *merge_cp_p is at a different index than
-        // the new entry in scratch_cp so we need to map the index values.
-        map_index(scratch_cp, scratch_i, *merge_cp_length_p);
-      }
-      (*merge_cp_length_p)++;
-    } break;
-
-    // these are direct CP entries so they can be directly appended,
-    // but double and long take two constant pool entries
-    case JVM_CONSTANT_Double:  // fall through
-    case JVM_CONSTANT_Long:
-    {
-      constantPoolOopDesc::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
-        THREAD);
-
-      if (scratch_i != *merge_cp_length_p) {
-        // The new entry in *merge_cp_p is at a different index than
-        // the new entry in scratch_cp so we need to map the index values.
-        map_index(scratch_cp, scratch_i, *merge_cp_length_p);
-      }
-      (*merge_cp_length_p) += 2;
-    } break;
-
-    // these are direct CP entries so they can be directly appended
-    case JVM_CONSTANT_Float:   // fall through
-    case JVM_CONSTANT_Integer: // fall through
-    case JVM_CONSTANT_Utf8:    // fall through
-
-    // This was an indirect CP entry, but it has been changed into
-    // an interned string so this entry can be directly appended.
-    case JVM_CONSTANT_String:      // fall through
-
-    // These were indirect CP entries, but they have been changed into
-    // Symbol*s so these entries can be directly appended.
-    case JVM_CONSTANT_UnresolvedClass:  // fall through
-    case JVM_CONSTANT_UnresolvedString:
-    {
-      constantPoolOopDesc::copy_entry_to(scratch_cp, scratch_i, *merge_cp_p, *merge_cp_length_p,
-        THREAD);
-
-      if (scratch_i != *merge_cp_length_p) {
-        // The new entry in *merge_cp_p is at a different index than
-        // the new entry in scratch_cp so we need to map the index values.
-        map_index(scratch_cp, scratch_i, *merge_cp_length_p);
-      }
-      (*merge_cp_length_p)++;
-    } break;
-
-    // this is an indirect CP entry so it needs special handling
-    case JVM_CONSTANT_NameAndType:
-    {
-      int name_ref_i = scratch_cp->name_ref_index_at(scratch_i);
-      int new_name_ref_i = 0;
-      bool match = (name_ref_i < *merge_cp_length_p) &&
-        scratch_cp->compare_entry_to(name_ref_i, *merge_cp_p, name_ref_i,
-          THREAD);
-      if (!match) {
-        // forward reference in *merge_cp_p or not a direct match
-
-        int found_i = scratch_cp->find_matching_entry(name_ref_i, *merge_cp_p,
-          THREAD);
-        if (found_i != 0) {
-          guarantee(found_i != name_ref_i,
-            "compare_entry_to() and find_matching_entry() do not agree");
-
-          // Found a matching entry somewhere else in *merge_cp_p so
-          // just need a mapping entry.
-          new_name_ref_i = found_i;
-          map_index(scratch_cp, name_ref_i, found_i);
-        } else {
-          // no match found so we have to append this entry to *merge_cp_p
-          append_entry(scratch_cp, name_ref_i, merge_cp_p, merge_cp_length_p,
-            THREAD);
-          // The above call to append_entry() can only append one entry
-          // so the post call query of *merge_cp_length_p is only for
-          // the sake of consistency.
-          new_name_ref_i = *merge_cp_length_p - 1;
-        }
-      }
-
-      int signature_ref_i = scratch_cp->signature_ref_index_at(scratch_i);
-      int new_signature_ref_i = 0;
-      match = (signature_ref_i < *merge_cp_length_p) &&
-        scratch_cp->compare_entry_to(signature_ref_i, *merge_cp_p,
-          signature_ref_i, THREAD);
-      if (!match) {
-        // forward reference in *merge_cp_p or not a direct match
-
-        int found_i = scratch_cp->find_matching_entry(signature_ref_i,
-          *merge_cp_p, THREAD);
-        if (found_i != 0) {
-          guarantee(found_i != signature_ref_i,
-            "compare_entry_to() and find_matching_entry() do not agree");
-
-          // Found a matching entry somewhere else in *merge_cp_p so
-          // just need a mapping entry.
-          new_signature_ref_i = found_i;
-          map_index(scratch_cp, signature_ref_i, found_i);
-        } else {
-          // no match found so we have to append this entry to *merge_cp_p
-          append_entry(scratch_cp, signature_ref_i, merge_cp_p,
-            merge_cp_length_p, THREAD);
-          // The above call to append_entry() can only append one entry
-          // so the post call query of *merge_cp_length_p is only for
-          // the sake of consistency.
-          new_signature_ref_i = *merge_cp_length_p - 1;
-        }
-      }
-
-      // If the referenced entries already exist in *merge_cp_p, then
-      // both new_name_ref_i and new_signature_ref_i will both be 0.
-      // In that case, all we are appending is the current entry.
-      if (new_name_ref_i == 0) {
-        new_name_ref_i = name_ref_i;
-      } else {
-        RC_TRACE(0x00080000,
-          ("NameAndType entry@%d name_ref_index change: %d to %d",
-          *merge_cp_length_p, name_ref_i, new_name_ref_i));
-      }
-      if (new_signature_ref_i == 0) {
-        new_signature_ref_i = signature_ref_i;
-      } else {
-        RC_TRACE(0x00080000,
-          ("NameAndType entry@%d signature_ref_index change: %d to %d",
-          *merge_cp_length_p, signature_ref_i, new_signature_ref_i));
-      }
-
-      (*merge_cp_p)->name_and_type_at_put(*merge_cp_length_p,
-        new_name_ref_i, new_signature_ref_i);
-      if (scratch_i != *merge_cp_length_p) {
-        // The new entry in *merge_cp_p is at a different index than
-        // the new entry in scratch_cp so we need to map the index values.
-        map_index(scratch_cp, scratch_i, *merge_cp_length_p);
-      }
-      (*merge_cp_length_p)++;
-    } break;
-
-    // this is a double-indirect CP entry so it needs special handling
-    case JVM_CONSTANT_Fieldref:           // fall through
-    case JVM_CONSTANT_InterfaceMethodref: // fall through
-    case JVM_CONSTANT_Methodref:
-    {
-      int klass_ref_i = scratch_cp->uncached_klass_ref_index_at(scratch_i);
-      int new_klass_ref_i = 0;
-      bool match = (klass_ref_i < *merge_cp_length_p) &&
-        scratch_cp->compare_entry_to(klass_ref_i, *merge_cp_p, klass_ref_i,
-          THREAD);
-      if (!match) {
-        // forward reference in *merge_cp_p or not a direct match
-
-        int found_i = scratch_cp->find_matching_entry(klass_ref_i, *merge_cp_p,
-          THREAD);
-        if (found_i != 0) {
-          guarantee(found_i != klass_ref_i,
-            "compare_entry_to() and find_matching_entry() do not agree");
-
-          // Found a matching entry somewhere else in *merge_cp_p so
-          // just need a mapping entry.
-          new_klass_ref_i = found_i;
-          map_index(scratch_cp, klass_ref_i, found_i);
-        } else {
-          // no match found so we have to append this entry to *merge_cp_p
-          append_entry(scratch_cp, klass_ref_i, merge_cp_p, merge_cp_length_p,
-            THREAD);
-          // The above call to append_entry() can only append one entry
-          // so the post call query of *merge_cp_length_p is only for
-          // the sake of consistency. Without the optimization where we
-          // use JVM_CONSTANT_UnresolvedClass, then up to two entries
-          // could be appended.
-          new_klass_ref_i = *merge_cp_length_p - 1;
-        }
-      }
-
-      int name_and_type_ref_i =
-        scratch_cp->uncached_name_and_type_ref_index_at(scratch_i);
-      int new_name_and_type_ref_i = 0;
-      match = (name_and_type_ref_i < *merge_cp_length_p) &&
-        scratch_cp->compare_entry_to(name_and_type_ref_i, *merge_cp_p,
-          name_and_type_ref_i, THREAD);
-      if (!match) {
-        // forward reference in *merge_cp_p or not a direct match
-
-        int found_i = scratch_cp->find_matching_entry(name_and_type_ref_i,
-          *merge_cp_p, THREAD);
-        if (found_i != 0) {
-          guarantee(found_i != name_and_type_ref_i,
-            "compare_entry_to() and find_matching_entry() do not agree");
-
-          // Found a matching entry somewhere else in *merge_cp_p so
-          // just need a mapping entry.
-          new_name_and_type_ref_i = found_i;
-          map_index(scratch_cp, name_and_type_ref_i, found_i);
-        } else {
-          // no match found so we have to append this entry to *merge_cp_p
-          append_entry(scratch_cp, name_and_type_ref_i, merge_cp_p,
-            merge_cp_length_p, THREAD);
-          // The above call to append_entry() can append more than
-          // one entry so the post call query of *merge_cp_length_p
-          // is required in order to get the right index for the
-          // JVM_CONSTANT_NameAndType entry.
-          new_name_and_type_ref_i = *merge_cp_length_p - 1;
-        }
-      }
-
-      // If the referenced entries already exist in *merge_cp_p, then
-      // both new_klass_ref_i and new_name_and_type_ref_i will both be
-      // 0. In that case, all we are appending is the current entry.
-      if (new_klass_ref_i == 0) {
-        new_klass_ref_i = klass_ref_i;
-      }
-      if (new_name_and_type_ref_i == 0) {
-        new_name_and_type_ref_i = name_and_type_ref_i;
-      }
-
-      const char *entry_name;
-      switch (scratch_cp->tag_at(scratch_i).value()) {
-      case JVM_CONSTANT_Fieldref:
-        entry_name = "Fieldref";
-        (*merge_cp_p)->field_at_put(*merge_cp_length_p, new_klass_ref_i,
-          new_name_and_type_ref_i);
-        break;
-      case JVM_CONSTANT_InterfaceMethodref:
-        entry_name = "IFMethodref";
-        (*merge_cp_p)->interface_method_at_put(*merge_cp_length_p,
-          new_klass_ref_i, new_name_and_type_ref_i);
-        break;
-      case JVM_CONSTANT_Methodref:
-        entry_name = "Methodref";
-        (*merge_cp_p)->method_at_put(*merge_cp_length_p, new_klass_ref_i,
-          new_name_and_type_ref_i);
-        break;
-      default:
-        guarantee(false, "bad switch");
-        break;
-      }
-
-      if (klass_ref_i != new_klass_ref_i) {
-        RC_TRACE(0x00080000, ("%s entry@%d class_index changed: %d to %d",
-          entry_name, *merge_cp_length_p, klass_ref_i, new_klass_ref_i));
-      }
-      if (name_and_type_ref_i != new_name_and_type_ref_i) {
-        RC_TRACE(0x00080000,
-          ("%s entry@%d name_and_type_index changed: %d to %d",
-          entry_name, *merge_cp_length_p, name_and_type_ref_i,
-          new_name_and_type_ref_i));
-      }
-
-      if (scratch_i != *merge_cp_length_p) {
-        // The new entry in *merge_cp_p is at a different index than
-        // the new entry in scratch_cp so we need to map the index values.
-        map_index(scratch_cp, scratch_i, *merge_cp_length_p);
-      }
-      (*merge_cp_length_p)++;
-    } break;
-
-    // At this stage, Class or UnresolvedClass could be here, but not
-    // ClassIndex
-    case JVM_CONSTANT_ClassIndex: // fall through
-
-    // Invalid is used as the tag for the second constant pool entry
-    // occupied by JVM_CONSTANT_Double or JVM_CONSTANT_Long. It should
-    // not be seen by itself.
-    case JVM_CONSTANT_Invalid: // fall through
-
-    // At this stage, String or UnresolvedString could be here, but not
-    // StringIndex
-    case JVM_CONSTANT_StringIndex: // fall through
-
-    // At this stage JVM_CONSTANT_UnresolvedClassInError should not be
-    // here
-    case JVM_CONSTANT_UnresolvedClassInError: // fall through
-
-    default:
-    {
-      // leave a breadcrumb
-      jbyte bad_value = scratch_cp->tag_at(scratch_i).value();
-      ShouldNotReachHere();
-    } break;
-  } // end switch tag value
-} // end append_entry()
-
-
-void VM_RedefineClasses::swap_all_method_annotations(int i, int j, instanceKlassHandle scratch_class) {
-  typeArrayOop save;
-
-  save = scratch_class->get_method_annotations_of(i);
-  scratch_class->set_method_annotations_of(i, scratch_class->get_method_annotations_of(j));
-  scratch_class->set_method_annotations_of(j, save);
-
-  save = scratch_class->get_method_parameter_annotations_of(i);
-  scratch_class->set_method_parameter_annotations_of(i, scratch_class->get_method_parameter_annotations_of(j));
-  scratch_class->set_method_parameter_annotations_of(j, save);
-
-  save = scratch_class->get_method_default_annotations_of(i);
-  scratch_class->set_method_default_annotations_of(i, scratch_class->get_method_default_annotations_of(j));
-  scratch_class->set_method_default_annotations_of(j, save);
-}
-
-
-jvmtiError VM_RedefineClasses::compare_and_normalize_class_versions(
-             instanceKlassHandle the_class,
-             instanceKlassHandle scratch_class) {
+jvmtiError VM_RedefineClasses::check_redefinition_allowed(instanceKlassHandle scratch_class) {
+
+
+  
+  // Compatibility mode => check for unsupported modification
+
+
+  assert(scratch_class->old_version() != NULL, "must have old version");
+  instanceKlassHandle the_class(scratch_class->old_version());
+
   int i;
 
   // Check superclasses, or rather their names, since superclasses themselves can be
   // requested to replace.
   // Check for NULL superclass first since this might be java.lang.Object
   if (the_class->super() != scratch_class->super() &&
-      (the_class->super() == NULL || scratch_class->super() == NULL ||
-       Klass::cast(the_class->super())->name() !=
-       Klass::cast(scratch_class->super())->name())) {
-    return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
+    (the_class->super() == NULL || scratch_class->super() == NULL ||
+    Klass::cast(the_class->super())->name() !=
+    Klass::cast(scratch_class->super())->name())) {
+      return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
   }
 
   // Check if the number, names and order of directly implemented interfaces are the same.
@@ -532,8 +678,8 @@
   }
   for (i = 0; i < n_intfs; i++) {
     if (Klass::cast((klassOop) k_interfaces->obj_at(i))->name() !=
-        Klass::cast((klassOop) k_new_interfaces->obj_at(i))->name()) {
-      return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
+      Klass::cast((klassOop) k_new_interfaces->obj_at(i))->name()) {
+        return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
     }
   }
 
@@ -682,12 +828,8 @@
             idnum_owner->set_method_idnum(new_num);
           }
           k_new_method->set_method_idnum(old_num);
-          swap_all_method_annotations(old_num, new_num, scratch_class);
         }
       }
-      RC_TRACE(0x00008000, ("Method matched: new: %s [%d] == old: %s [%d]",
-                            k_new_method->name_and_sig_as_C_string(), ni,
-                            k_old_method->name_and_sig_as_C_string(), oi));
       // advance to next pair of methods
       ++oi;
       ++ni;
@@ -696,11 +838,11 @@
       // method added, see if it is OK
       new_flags = (jushort) k_new_method->access_flags().get_flags();
       if ((new_flags & JVM_ACC_PRIVATE) == 0
-           // hack: private should be treated as final, but alas
-          || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
-         ) {
-        // new methods must be private
-        return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
+        // hack: private should be treated as final, but alas
+        || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
+        ) {
+          // new methods must be private
+          return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED;
       }
       {
         u2 num = the_class->next_method_idnum();
@@ -715,24 +857,19 @@
           idnum_owner->set_method_idnum(new_num);
         }
         k_new_method->set_method_idnum(num);
-        swap_all_method_annotations(new_num, num, scratch_class);
       }
-      RC_TRACE(0x00008000, ("Method added: new: %s [%d]",
-                            k_new_method->name_and_sig_as_C_string(), ni));
       ++ni; // advance to next new method
       break;
     case deleted:
       // method deleted, see if it is OK
       old_flags = (jushort) k_old_method->access_flags().get_flags();
       if ((old_flags & JVM_ACC_PRIVATE) == 0
-           // hack: private should be treated as final, but alas
-          || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
-         ) {
-        // deleted methods must be private
-        return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
+        // hack: private should be treated as final, but alas
+        || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
+        ) {
+          // deleted methods must be private
+          return JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED;
       }
-      RC_TRACE(0x00008000, ("Method deleted: old: %s [%d]",
-                            k_old_method->name_and_sig_as_C_string(), oi));
       ++oi; // advance to next old method
       break;
     default:
@@ -743,2084 +880,2272 @@
   return JVMTI_ERROR_NONE;
 }
 
-
-// Find new constant pool index value for old constant pool index value
-// by seaching the index map. Returns zero (0) if there is no mapped
-// value for the old constant pool index.
-int VM_RedefineClasses::find_new_index(int old_index) {
-  if (_index_map_count == 0) {
-    // map is empty so nothing can be found
-    return 0;
+int VM_RedefineClasses::calculate_redefinition_flags(instanceKlassHandle new_class) {
+
+  int result = Klass::NoRedefinition;
+
+
+
+  RC_TRACE(0x00000002, ("Comparing different class versions of class %s",
+    new_class->name()->as_C_string()));
+
+  assert(new_class->old_version() != NULL, "must have old version");
+  instanceKlassHandle the_class(new_class->old_version());
+
+  // Check whether class is in the error init state.
+  if (the_class->is_in_error_state()) {
+    // TBD #5057930: special error code is needed in 1.6
+    //result = Klass::union_redefinition_level(result, Klass::Invalid);
   }
 
-  if (old_index < 1 || old_index >= _index_map_p->length()) {
-    // The old_index is out of range so it is not mapped. This should
-    // not happen in regular constant pool merging use, but it can
-    // happen if a corrupt annotation is processed.
-    return 0;
+  int i;
+
+  //////////////////////////////////////////////////////////////////////////////////////////////////////////
+  // Check superclasses
+  assert(new_class->super() == NULL || new_class->super()->klass_part()->is_newest_version(), "");
+  if (the_class->super() != new_class->super()) {
+    // Super class changed
+
+    klassOop cur_klass = the_class->super();
+    while (cur_klass != NULL) {
+      if (!new_class->is_subclass_of(cur_klass->klass_part()->newest_version())) {
+        RC_TRACE(0x00000002, ("Removed super class %s",
+          cur_klass->klass_part()->name()->as_C_string()));
+        result = result | Klass::RemoveSuperType | Klass::ModifyInstances | Klass::ModifyClass;
+
+        if (!cur_klass->klass_part()->has_subtype_changed()) {
+          RC_TRACE(0x00000002, ("Subtype changed of class %s",
+            cur_klass->klass_part()->name()->as_C_string()));
+          cur_klass->klass_part()->set_subtype_changed(true);
+        }
+      }
+
+      cur_klass = cur_klass->klass_part()->super();
+    }
+
+    cur_klass = new_class->super();
+    while (cur_klass != NULL) {
+      if (!the_class->is_subclass_of(cur_klass->klass_part()->old_version())) {
+        RC_TRACE(0x00000002, ("Added super class %s",
+          cur_klass->klass_part()->name()->as_C_string()));
+        result = result | Klass::ModifyClass | Klass::ModifyInstances;
+      }
+      cur_klass = cur_klass->klass_part()->super();
+    }
   }
 
-  int value = _index_map_p->at(old_index);
-  if (value == -1) {
-    // the old_index is not mapped
-    return 0;
-  }
-
-  return value;
-} // end find_new_index()
-
-
-// Returns true if the current mismatch is due to a resolved/unresolved
-// class pair. Otherwise, returns false.
-bool VM_RedefineClasses::is_unresolved_class_mismatch(constantPoolHandle cp1,
-       int index1, constantPoolHandle cp2, int index2) {
-
-  jbyte t1 = cp1->tag_at(index1).value();
-  if (t1 != JVM_CONSTANT_Class && t1 != JVM_CONSTANT_UnresolvedClass) {
-    return false;  // wrong entry type; not our special case
-  }
-
-  jbyte t2 = cp2->tag_at(index2).value();
-  if (t2 != JVM_CONSTANT_Class && t2 != JVM_CONSTANT_UnresolvedClass) {
-    return false;  // wrong entry type; not our special case
-  }
-
-  if (t1 == t2) {
-    return false;  // not a mismatch; not our special case
-  }
-
-  char *s1 = cp1->klass_name_at(index1)->as_C_string();
-  char *s2 = cp2->klass_name_at(index2)->as_C_string();
-  if (strcmp(s1, s2) != 0) {
-    return false;  // strings don't match; not our special case
-  }
-
-  return true;  // made it through the gauntlet; this is our special case
-} // end is_unresolved_class_mismatch()
-
-
-// Returns true if the current mismatch is due to a resolved/unresolved
-// string pair. Otherwise, returns false.
-bool VM_RedefineClasses::is_unresolved_string_mismatch(constantPoolHandle cp1,
-       int index1, constantPoolHandle cp2, int index2) {
-
-  jbyte t1 = cp1->tag_at(index1).value();
-  if (t1 != JVM_CONSTANT_String && t1 != JVM_CONSTANT_UnresolvedString) {
-    return false;  // wrong entry type; not our special case
-  }
-
-  jbyte t2 = cp2->tag_at(index2).value();
-  if (t2 != JVM_CONSTANT_String && t2 != JVM_CONSTANT_UnresolvedString) {
-    return false;  // wrong entry type; not our special case
-  }
-
-  if (t1 == t2) {
-    return false;  // not a mismatch; not our special case
-  }
-
-  char *s1 = cp1->string_at_noresolve(index1);
-  char *s2 = cp2->string_at_noresolve(index2);
-  if (strcmp(s1, s2) != 0) {
-    return false;  // strings don't match; not our special case
-  }
-
-  return true;  // made it through the gauntlet; this is our special case
-} // end is_unresolved_string_mismatch()
-
-
-jvmtiError VM_RedefineClasses::load_new_class_versions(TRAPS) {
-  // For consistency allocate memory using os::malloc wrapper.
-  _scratch_classes = (instanceKlassHandle *)
-    os::malloc(sizeof(instanceKlassHandle) * _class_count);
-  if (_scratch_classes == NULL) {
-    return JVMTI_ERROR_OUT_OF_MEMORY;
-  }
-
-  ResourceMark rm(THREAD);
-
-  JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
-  // state can only be NULL if the current thread is exiting which
-  // should not happen since we're trying to do a RedefineClasses
-  guarantee(state != NULL, "exiting thread calling load_new_class_versions");
-  for (int i = 0; i < _class_count; i++) {
-    oop mirror = JNIHandles::resolve_non_null(_class_defs[i].klass);
-    // classes for primitives cannot be redefined
-    if (!is_modifiable_class(mirror)) {
-      return JVMTI_ERROR_UNMODIFIABLE_CLASS;
-    }
-    klassOop the_class_oop = java_lang_Class::as_klassOop(mirror);
-    instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
-    Symbol*  the_class_sym = the_class->name();
-
-    // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
-    RC_TRACE_WITH_THREAD(0x00000001, THREAD,
-      ("loading name=%s kind=%d (avail_mem=" UINT64_FORMAT "K)",
-      the_class->external_name(), _class_load_kind,
-      os::available_memory() >> 10));
-
-    ClassFileStream st((u1*) _class_defs[i].class_bytes,
-      _class_defs[i].class_byte_count, (char *)"__VM_RedefineClasses__");
-
-    // Parse the stream.
-    Handle the_class_loader(THREAD, the_class->class_loader());
-    Handle protection_domain(THREAD, the_class->protection_domain());
-    // Set redefined class handle in JvmtiThreadState class.
-    // This redefined class is sent to agent event handler for class file
-    // load hook event.
-    state->set_class_being_redefined(&the_class, _class_load_kind);
-
-    klassOop k = SystemDictionary::parse_stream(the_class_sym,
-                                                the_class_loader,
-                                                protection_domain,
-                                                &st,
-                                                THREAD);
-    // Clear class_being_redefined just to be sure.
-    state->clear_class_being_redefined();
-
-    // TODO: if this is retransform, and nothing changed we can skip it
-
-    instanceKlassHandle scratch_class (THREAD, k);
-
-    if (HAS_PENDING_EXCEPTION) {
-      Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
-      // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
-      RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("parse_stream exception: '%s'",
-        ex_name->as_C_string()));
-      CLEAR_PENDING_EXCEPTION;
-
-      if (ex_name == vmSymbols::java_lang_UnsupportedClassVersionError()) {
-        return JVMTI_ERROR_UNSUPPORTED_VERSION;
-      } else if (ex_name == vmSymbols::java_lang_ClassFormatError()) {
-        return JVMTI_ERROR_INVALID_CLASS_FORMAT;
-      } else if (ex_name == vmSymbols::java_lang_ClassCircularityError()) {
-        return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
-      } else if (ex_name == vmSymbols::java_lang_NoClassDefFoundError()) {
-        // The message will be "XXX (wrong name: YYY)"
-        return JVMTI_ERROR_NAMES_DONT_MATCH;
-      } else if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
-        return JVMTI_ERROR_OUT_OF_MEMORY;
-      } else {  // Just in case more exceptions can be thrown..
-        return JVMTI_ERROR_FAILS_VERIFICATION;
+  //////////////////////////////////////////////////////////////////////////////////////////////////////////
+  // Check interfaces
+
+  // Interfaces removed?
+  objArrayOop old_interfaces = the_class->transitive_interfaces();
+  for (i = 0; i<old_interfaces->length(); i++) {
+    instanceKlassHandle old_interface((klassOop)old_interfaces->obj_at(i));
+    if (!new_class->implements_interface_any_version(old_interface())) {
+      result = result | Klass::RemoveSuperType | Klass::ModifyClass;
+      RC_TRACE(0x00000002, ("Removed interface %s",
+        old_interface->name()->as_C_string()));
+      
+      if (!old_interface->has_subtype_changed()) {
+        RC_TRACE(0x00000002, ("Subtype changed of interface %s",
+          old_interface->name()->as_C_string()));
+        old_interface->set_subtype_changed(true);
       }
     }
-
-    // Ensure class is linked before redefine
-    if (!the_class->is_linked()) {
-      the_class->link_class(THREAD);
-      if (HAS_PENDING_EXCEPTION) {
-        Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
-        // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
-        RC_TRACE_WITH_THREAD(0x00000002, THREAD, ("link_class exception: '%s'",
-          ex_name->as_C_string()));
-        CLEAR_PENDING_EXCEPTION;
-        if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
-          return JVMTI_ERROR_OUT_OF_MEMORY;
+  }
+
+  // Interfaces added?
+  objArrayOop new_interfaces = new_class->transitive_interfaces();
+  for (i = 0; i<new_interfaces->length(); i++) {
+    if (!the_class->implements_interface_any_version((klassOop)new_interfaces->obj_at(i))) {
+      result = result | Klass::ModifyClass;
+      RC_TRACE(0x00000002, ("Added interface %s",
+        ((klassOop)new_interfaces->obj_at(i))->klass_part()->name()->as_C_string()));
+    }
+  }
+
+
+  // Check whether class modifiers are the same.
+  jushort old_flags = (jushort) the_class->access_flags().get_flags();
+  jushort new_flags = (jushort) new_class->access_flags().get_flags();
+  if (old_flags != new_flags) {
+    // TODO (tw): Can this have any effects?
+  }
+
+  // Check if the number, names, types and order of fields declared in these classes
+  // are the same.
+  JavaFieldStream old_fs(the_class);
+  JavaFieldStream new_fs(new_class);
+  for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
+    // access
+    old_flags = old_fs.access_flags().as_short();
+    new_flags = new_fs.access_flags().as_short();
+    if ((old_flags ^ new_flags) & JVM_RECOGNIZED_FIELD_MODIFIERS) {
+      // (tw) Can this have any effects?
+    }
+    // offset
+    if (old_fs.offset() != new_fs.offset()) {
+        result = result | Klass::ModifyInstances;
+    }
+    // name and signature
+    Symbol* name_sym1 = the_class->constants()->symbol_at(old_fs.name_index());
+    Symbol* sig_sym1 = the_class->constants()->symbol_at(old_fs.signature_index());
+    Symbol* name_sym2 = new_class->constants()->symbol_at(new_fs.name_index());
+    Symbol* sig_sym2 = new_class->constants()->symbol_at(new_fs.signature_index());
+    if (name_sym1 != name_sym2 || sig_sym1 != sig_sym2) {
+      result = result | Klass::ModifyInstances;
+    }
+  }
+
+  if (!old_fs.done() || !new_fs.done()) {
+    result = result | Klass::ModifyInstances;
+  }
+
+  // Do a parallel walk through the old and new methods. Detect
+  // cases where they match (exist in both), have been added in
+  // the new methods, or have been deleted (exist only in the
+  // old methods).  The class file parser places methods in order
+  // by method name, but does not order overloaded methods by
+  // signature.  In order to determine what fate befell the methods,
+  // this code places the overloaded new methods that have matching
+  // old methods in the same order as the old methods and places
+  // new overloaded methods at the end of overloaded methods of
+  // that name. The code for this order normalization is adapted
+  // from the algorithm used in instanceKlass::find_method().
+  // Since we are swapping out of order entries as we find them,
+  // we only have to search forward through the overloaded methods.
+  // Methods which are added and have the same name as an existing
+  // method (but different signature) will be put at the end of
+  // the methods with that name, and the name mismatch code will
+  // handle them.
+  objArrayHandle k_old_methods(the_class->methods());
+  objArrayHandle k_new_methods(new_class->methods());
+  int n_old_methods = k_old_methods->length();
+  int n_new_methods = k_new_methods->length();
+
+  int ni = 0;
+  int oi = 0;
+  while (true) {
+    methodOop k_old_method;
+    methodOop k_new_method;
+    enum { matched, added, deleted, undetermined } method_was = undetermined;
+
+    if (oi >= n_old_methods) {
+      if (ni >= n_new_methods) {
+        break; // we've looked at everything, done
+      }
+      // New method at the end
+      k_new_method = (methodOop) k_new_methods->obj_at(ni);
+      method_was = added;
+    } else if (ni >= n_new_methods) {
+      // Old method, at the end, is deleted
+      k_old_method = (methodOop) k_old_methods->obj_at(oi);
+      method_was = deleted;
+    } else {
+      // There are more methods in both the old and new lists
+      k_old_method = (methodOop) k_old_methods->obj_at(oi);
+      k_new_method = (methodOop) k_new_methods->obj_at(ni);
+      if (k_old_method->name() != k_new_method->name()) {
+        // Methods are sorted by method name, so a mismatch means added
+        // or deleted
+        if (k_old_method->name()->fast_compare(k_new_method->name()) > 0) {
+          method_was = added;
         } else {
-          return JVMTI_ERROR_INTERNAL;
+          method_was = deleted;
+        }
+      } else if (k_old_method->signature() == k_new_method->signature()) {
+        // Both the name and signature match
+        method_was = matched;
+      } else {
+        // The name matches, but the signature doesn't, which means we have to
+        // search forward through the new overloaded methods.
+        int nj;  // outside the loop for post-loop check
+        for (nj = ni + 1; nj < n_new_methods; nj++) {
+          methodOop m = (methodOop)k_new_methods->obj_at(nj);
+          if (k_old_method->name() != m->name()) {
+            // reached another method name so no more overloaded methods
+            method_was = deleted;
+            break;
+          }
+          if (k_old_method->signature() == m->signature()) {
+            // found a match so swap the methods
+            k_new_methods->obj_at_put(ni, m);
+            k_new_methods->obj_at_put(nj, k_new_method);
+            k_new_method = m;
+            method_was = matched;
+            break;
+          }
+        }
+
+        if (nj >= n_new_methods) {
+          // reached the end without a match; so method was deleted
+          method_was = deleted;
         }
       }
     }
 
-    // Do the validity checks in compare_and_normalize_class_versions()
-    // before verifying the byte codes. By doing these checks first, we
-    // limit the number of functions that require redirection from
-    // the_class to scratch_class. In particular, we don't have to
-    // modify JNI GetSuperclass() and thus won't change its performance.
-    jvmtiError res = compare_and_normalize_class_versions(the_class,
-                       scratch_class);
-    if (res != JVMTI_ERROR_NONE) {
-      return res;
+    switch (method_was) {
+  case matched:
+    // methods match, be sure modifiers do too
+    old_flags = (jushort) k_old_method->access_flags().get_flags();
+    new_flags = (jushort) k_new_method->access_flags().get_flags();
+    if ((old_flags ^ new_flags) & ~(JVM_ACC_NATIVE)) {
+      // (tw) Can this have any effects? Probably yes on vtables?
+      result = result | Klass::ModifyClass;
     }
-
-    // verify what the caller passed us
     {
-      // The bug 6214132 caused the verification to fail.
-      // Information about the_class and scratch_class is temporarily
-      // recorded into jvmtiThreadState. This data is used to redirect
-      // the_class to scratch_class in the JVM_* functions called by the
-      // verifier. Please, refer to jvmtiThreadState.hpp for the detailed
-      // description.
-      RedefineVerifyMark rvm(&the_class, &scratch_class, state);
-      Verifier::verify(
-        scratch_class, Verifier::ThrowException, true, THREAD);
-    }
-
-    if (HAS_PENDING_EXCEPTION) {
-      Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
-      // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
-      RC_TRACE_WITH_THREAD(0x00000002, THREAD,
-        ("verify_byte_codes exception: '%s'", ex_name->as_C_string()));
-      CLEAR_PENDING_EXCEPTION;
-      if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
-        return JVMTI_ERROR_OUT_OF_MEMORY;
-      } else {
-        // tell the caller the bytecodes are bad
-        return JVMTI_ERROR_FAILS_VERIFICATION;
+      u2 new_num = k_new_method->method_idnum();
+      u2 old_num = k_old_method->method_idnum();
+      if (new_num != old_num) {
+        methodOop idnum_owner = new_class->method_with_idnum(old_num);
+        if (idnum_owner != NULL) {
+          // There is already a method assigned this idnum -- switch them
+          idnum_owner->set_method_idnum(new_num);
+        }
+        k_new_method->set_method_idnum(old_num);
+        RC_TRACE(0x00000002, ("swapping idnum of new and old method %d / %d!",
+          new_num,
+          old_num));
+       // swap_all_method_annotations(old_num, new_num, new_class);
       }
     }
-
-    res = merge_cp_and_rewrite(the_class, scratch_class, THREAD);
-    if (res != JVMTI_ERROR_NONE) {
-      return res;
+    RC_TRACE(0x00008000, ("Method matched: new: %s [%d] == old: %s [%d]",
+      k_new_method->name_and_sig_as_C_string(), ni,
+      k_old_method->name_and_sig_as_C_string(), oi));
+    // advance to next pair of methods
+    ++oi;
+    ++ni;
+    break;
+  case added:
+    // method added, see if it is OK
+    new_flags = (jushort) k_new_method->access_flags().get_flags();
+    if ((new_flags & JVM_ACC_PRIVATE) == 0
+      // hack: private should be treated as final, but alas
+      || (new_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
+      ) {
+        // new methods must be private
+        result = result | Klass::ModifyClass;
     }
-
-    if (VerifyMergedCPBytecodes) {
-      // verify what we have done during constant pool merging
-      {
-        RedefineVerifyMark rvm(&the_class, &scratch_class, state);
-        Verifier::verify(scratch_class, Verifier::ThrowException, true, THREAD);
+    {
+      u2 num = the_class->next_method_idnum();
+      if (num == constMethodOopDesc::UNSET_IDNUM) {
+        // cannot add any more methods
+        result = result | Klass::ModifyClass;
       }
-
-      if (HAS_PENDING_EXCEPTION) {
-        Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
-        // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
-        RC_TRACE_WITH_THREAD(0x00000002, THREAD,
-          ("verify_byte_codes post merge-CP exception: '%s'",
-          ex_name->as_C_string()));
-        CLEAR_PENDING_EXCEPTION;
-        if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
-          return JVMTI_ERROR_OUT_OF_MEMORY;
-        } else {
-          // tell the caller that constant pool merging screwed up
-          return JVMTI_ERROR_INTERNAL;
+      u2 new_num = k_new_method->method_idnum();
+      methodOop idnum_owner = new_class->method_with_idnum(num);
+      if (idnum_owner != NULL) {
+        // There is already a method assigned this idnum -- switch them
+        idnum_owner->set_method_idnum(new_num);
+      }
+      k_new_method->set_method_idnum(num);
+      //swap_all_method_annotations(new_num, num, new_class);
+    }
+    RC_TRACE(0x00000001, ("Method added: new: %s [%d]",
+      k_new_method->name_and_sig_as_C_string(), ni));
+    ++ni; // advance to next new method
+    break;
+  case deleted:
+    // method deleted, see if it is OK
+    old_flags = (jushort) k_old_method->access_flags().get_flags();
+    if ((old_flags & JVM_ACC_PRIVATE) == 0
+      // hack: private should be treated as final, but alas
+      || (old_flags & (JVM_ACC_FINAL|JVM_ACC_STATIC)) == 0
+      ) {
+        // deleted methods must be private
+        result = result | Klass::ModifyClass;
+    }
+    RC_TRACE(0x00000001, ("Method deleted: old: %s [%d]",
+      k_old_method->name_and_sig_as_C_string(), oi));
+    ++oi; // advance to next old method
+    break;
+  default:
+    ShouldNotReachHere();
+    }
+  }
+
+  if (new_class()->size() != new_class->old_version()->size()) {
+    result |= Klass::ModifyClassSize;
+  }
+
+  if (new_class->size_helper() != ((instanceKlass*)(new_class->old_version()->klass_part()))->size_helper()) {
+    result |= Klass::ModifyInstanceSize;
+  }
+
+  methodHandle instanceTransformerMethod(new_class->find_method(vmSymbols::transformer_name(), vmSymbols::void_method_signature()));
+  if (!instanceTransformerMethod.is_null() && !instanceTransformerMethod->is_static()) {
+    result |= Klass::HasInstanceTransformer;
+  }
+
+  // (tw) Check method bodies to be able to return NoChange?
+  return result;
+}
+
+void VM_RedefineClasses::calculate_instance_update_information(klassOop new_version) {
+
+  class UpdateFieldsEvolutionClosure : public FieldEvolutionClosure {
+
+  private:
+
+    GrowableArray<int> info;
+    int curPosition;
+    bool copy_backwards;
+
+  public:
+
+    bool does_copy_backwards() {
+      return copy_backwards;
+    }
+
+    UpdateFieldsEvolutionClosure(klassOop klass) {
+
+      int base_offset = instanceOopDesc::base_offset_in_bytes();
+
+      if (klass->klass_part()->newest_version() == SystemDictionary::Reference_klass()->klass_part()->newest_version()) {
+        base_offset += java_lang_ref_Reference::number_of_fake_oop_fields*size_of_type(T_OBJECT);
+      }
+
+      info.append(base_offset);
+      info.append(0);
+      curPosition = base_offset;
+      copy_backwards = false;
+    }
+
+    GrowableArray<int> &finish() {
+      info.append(0);
+      return info;
+    }
+
+    virtual void do_new_field(fieldDescriptor* fd){
+      int alignment = fd->offset() - curPosition;
+      if (alignment > 0) {
+        // This field was aligned, so we need to make sure that we fill the gap
+        fill(alignment);
+      }
+
+      int size = size_of_type(fd->field_type());
+      fill(size);
+    }
+
+  private:
+
+    void fill(int size) {
+      if (info.length() > 0 && info.at(info.length() - 1) < 0) {
+        (*info.adr_at(info.length() - 1)) -= size;
+      } else {
+        info.append(-size);
+      }
+
+      curPosition += size;
+    }
+
+    int size_of_type(BasicType type) {
+      int size = 0;
+      switch(type) {
+        case T_BOOLEAN:
+          size = sizeof(jboolean);
+          break;
+
+        case T_CHAR:
+          size = (sizeof(jchar));
+          break;
+
+        case T_FLOAT:
+          size = (sizeof(jfloat));
+          break;
+
+        case T_DOUBLE:
+          size = (sizeof(jdouble));
+          break;
+
+        case T_BYTE:
+          size = (sizeof(jbyte));
+          break;
+
+        case T_SHORT:
+          size = (sizeof(jshort));
+          break;
+
+        case T_INT:
+          size = (sizeof(jint));
+          break;
+
+        case T_LONG:
+          size = (sizeof(jlong));
+          break;
+
+        case T_OBJECT:
+        case T_ARRAY:
+          if (UseCompressedOops) {
+            size = sizeof(narrowOop);
+          } else {
+            size = (sizeof(oop));
+          }
+          break;
+
+        default:
+          ShouldNotReachHere();
+      }
+
+      assert(size > 0, "");
+      return size;
+
+    }
+    
+  public:
+
+    virtual void do_old_field(fieldDescriptor* fd){}
+
+    virtual void do_changed_field(fieldDescriptor* old_fd, fieldDescriptor *new_fd){
+
+      int alignment = new_fd->offset() - curPosition;
+      if (alignment > 0) {
+        // This field was aligned, so we need to make sure that we fill the gap
+        fill(alignment);
+      }
+
+      assert(old_fd->field_type() == new_fd->field_type(), "");
+      assert(curPosition == new_fd->offset(), "must be correct offset!");
+
+      int offset = old_fd->offset();
+      int size = size_of_type(old_fd->field_type());
+
+      int prevEnd = -1;
+      if (info.length() > 0 && info.at(info.length() - 1) > 0) {
+        prevEnd = info.at(info.length() - 2) + info.at(info.length() - 1);
+      }
+
+      if (prevEnd == offset) {
+        info.at_put(info.length() - 2, info.at(info.length() - 2) + size);
+      } else {
+        info.append(size);
+        info.append(offset);
+      }
+
+      if (old_fd->offset() < new_fd->offset()) {
+        copy_backwards = true;
+      }
+
+      transfer_special_access_flags(old_fd, new_fd);
+
+      curPosition += size;
+    }
+  };
+
+  UpdateFieldsEvolutionClosure cl(new_version);
+  ((instanceKlass*)new_version->klass_part())->do_fields_evolution(&cl);
+
+  GrowableArray<int> result = cl.finish();
+  ((instanceKlass*)new_version->klass_part())->store_update_information(result);
+  ((instanceKlass*)new_version->klass_part())->set_copying_backwards(cl.does_copy_backwards());
+
+  if (RC_TRACE_ENABLED(0x00000002))  {
+    RC_TRACE(0x00000002, ("Instance update information for %s:",
+      new_version->klass_part()->name()->as_C_string()));
+    if (cl.does_copy_backwards()) {
+      RC_TRACE(0x00000002, ("\tDoes copy backwards!"));
+    }
+    for (int i=0; i<result.length(); i++) {
+      int curNum = result.at(i);
+      if (curNum < 0) {
+        RC_TRACE(0x00000002, ("\t%d CLEAN", curNum));
+      } else if (curNum > 0) {
+        RC_TRACE(0x00000002, ("\t%d COPY from %d", curNum, result.at(i + 1)));
+        i++;
+      } else {
+        RC_TRACE(0x00000002, ("\tEND"));
+      }
+    }
+  }
+}
+
+Symbol* VM_RedefineClasses::signature_to_class_name(Symbol* signature) {
+  assert(FieldType::is_obj(signature), "");
+  return SymbolTable::new_symbol(signature->as_C_string() + 1, signature->utf8_length() - 2, Thread::current());
+}
+
+void VM_RedefineClasses::calculate_type_check_information(klassOop klass) {
+  if (klass->klass_part()->is_redefining()) {
+    klass = klass->klass_part()->old_version();
+  }
+
+  // We found an instance klass!
+  instanceKlass *cur_instance_klass = instanceKlass::cast(klass);
+  GrowableArray< Pair<int, klassOop> > type_check_information;
+
+  class MyFieldClosure : public FieldClosure {
+
+  public:
+
+    GrowableArray< Pair<int, klassOop> > *_arr;
+
+    MyFieldClosure(GrowableArray< Pair<int, klassOop> > *arr) {
+      _arr = arr;
+    }
+
+    virtual void do_field(fieldDescriptor* fd) {
+      if (fd->field_type() == T_OBJECT) {
+        Symbol* signature = fd->signature();
+        if (FieldType::is_obj(signature)) {
+          Symbol* name = signature_to_class_name(signature);
+          klassOop field_klass;
+          if (is_field_dangerous(name, fd, field_klass)) {
+            RC_TRACE(0x00000002, ("Found dangerous field %s in klass %s of type %s",
+              fd->name()->as_C_string(),
+              fd->field_holder()->klass_part()->name()->as_C_string(),
+              name->as_C_string()));
+            _arr->append(Pair<int, klassOop>(fd->offset(), field_klass->klass_part()->newest_version()));
+          }
+        }
+
+        // Array fields can never be a problem!
+      }
+    }
+
+    bool is_field_dangerous(Symbol* klass_name, fieldDescriptor *fd, klassOop &field_klass) {
+      field_klass = SystemDictionary::find(klass_name, fd->field_holder()->klass_part()->class_loader(),
+              fd->field_holder()->klass_part()->protection_domain(), Thread::current());
+      if(field_klass != NULL) {
+        if (field_klass->klass_part()->is_redefining()) {
+          field_klass = field_klass->klass_part()->old_version();
+        }
+        if (field_klass->klass_part()->has_subtype_changed()) {
+          return true;
+        }
+      }
+      return false;
+    }
+  };
+
+  MyFieldClosure fieldClosure(&type_check_information);
+  cur_instance_klass->do_nonstatic_fields(&fieldClosure);
+
+  if (type_check_information.length() > 0) {
+    type_check_information.append(Pair<int, klassOop>(-1, NULL));
+    cur_instance_klass->store_type_check_information(type_check_information);
+  }
+}
+
+bool VM_RedefineClasses::check_field_value_types() {
+
+  Thread *THREAD = Thread::current();
+  class CheckFieldTypesClosure : public ObjectClosure {
+
+  private:
+
+    bool _result;
+
+  public:
+
+    CheckFieldTypesClosure() {
+      _result = true;
+    }
+
+    bool result() { return _result; }
+
+    virtual void do_object(oop obj) {
+
+      if (!_result) {
+        return;
+      }
+
+      if (obj->is_objArray()) {
+
+        objArrayOop array = objArrayOop(obj);
+
+        klassOop element_klass = objArrayKlass::cast(array->klass())->element_klass();
+
+        if (element_klass->klass_part()->has_subtype_changed()) {
+          int length = array->length();
+          for (int i=0; i<length; i++) {
+            oop element = array->obj_at(i);
+            if (element != NULL && element->blueprint()->newest_version()->klass_part()->is_redefining()) {
+              // Check subtype relationship to static type of array
+              if (!element->blueprint()->newest_version()->klass_part()->is_subtype_of(element_klass->klass_part()->newest_version())) {
+                RC_TRACE(0x00000001, ("Array value is INVALID - abort redefinition (static_type=%s, index=%d, dynamic_type=%s)",
+                  element_klass->klass_part()->name()->as_C_string(),
+                  i,
+                  element->blueprint()->name()->as_C_string()));
+                _result = false;
+                break;
+              }
+            }
+          }
+        }
+
+      } else {
+        Pair<int, klassOop> *cur = obj->klass()->klass_part()->type_check_information();
+        if (cur != NULL) {
+          // Type check information exists for this oop
+          while ((*cur).left() != -1) {
+            check_field(obj, (*cur).left(), (*cur).right());
+            cur++;
+          }
         }
       }
     }
 
-    Rewriter::rewrite(scratch_class, THREAD);
-    if (!HAS_PENDING_EXCEPTION) {
-      Rewriter::relocate_and_link(scratch_class, THREAD);
-    }
-    if (HAS_PENDING_EXCEPTION) {
-      Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
-      CLEAR_PENDING_EXCEPTION;
-      if (ex_name == vmSymbols::java_lang_OutOfMemoryError()) {
-        return JVMTI_ERROR_OUT_OF_MEMORY;
-      } else {
-        return JVMTI_ERROR_INTERNAL;
-      }
-    }
-
-    _scratch_classes[i] = scratch_class;
-
-    // RC_TRACE_WITH_THREAD macro has an embedded ResourceMark
-    RC_TRACE_WITH_THREAD(0x00000001, THREAD,
-      ("loaded name=%s (avail_mem=" UINT64_FORMAT "K)",
-      the_class->external_name(), os::available_memory() >> 10));
-  }
-
-  return JVMTI_ERROR_NONE;
-}
-
-
-// Map old_index to new_index as needed. scratch_cp is only needed
-// for RC_TRACE() calls.
-void VM_RedefineClasses::map_index(constantPoolHandle scratch_cp,
-       int old_index, int new_index) {
-  if (find_new_index(old_index) != 0) {
-    // old_index is already mapped
-    return;
-  }
-
-  if (old_index == new_index) {
-    // no mapping is needed
-    return;
-  }
-
-  _index_map_p->at_put(old_index, new_index);
-  _index_map_count++;
-
-  RC_TRACE(0x00040000, ("mapped tag %d at index %d to %d",
-    scratch_cp->tag_at(old_index).value(), old_index, new_index));
-} // end map_index()
-
-
-// Merge old_cp and scratch_cp and return the results of the merge via
-// merge_cp_p. The number of entries in *merge_cp_p is returned via
-// merge_cp_length_p. The entries in old_cp occupy the same locations
-// in *merge_cp_p. Also creates a map of indices from entries in
-// scratch_cp to the corresponding entry in *merge_cp_p. Index map
-// entries are only created for entries in scratch_cp that occupy a
-// different location in *merged_cp_p.
-bool VM_RedefineClasses::merge_constant_pools(constantPoolHandle old_cp,
-       constantPoolHandle scratch_cp, constantPoolHandle *merge_cp_p,
-       int *merge_cp_length_p, TRAPS) {
-
-  if (merge_cp_p == NULL) {
-    assert(false, "caller must provide scatch constantPool");
-    return false; // robustness
-  }
-  if (merge_cp_length_p == NULL) {
-    assert(false, "caller must provide scatch CP length");
-    return false; // robustness
-  }
-  // Worst case we need old_cp->length() + scratch_cp()->length(),
-  // but the caller might be smart so make sure we have at least
-  // the minimum.
-  if ((*merge_cp_p)->length() < old_cp->length()) {
-    assert(false, "merge area too small");
-    return false; // robustness
-  }
-
-  RC_TRACE_WITH_THREAD(0x00010000, THREAD,
-    ("old_cp_len=%d, scratch_cp_len=%d", old_cp->length(),
-    scratch_cp->length()));
-
-  {
-    // Pass 0:
-    // The old_cp is copied to *merge_cp_p; this means that any code
-    // using old_cp does not have to change. This work looks like a
-    // perfect fit for constantPoolOop::copy_cp_to(), but we need to
-    // handle one special case:
-    // - revert JVM_CONSTANT_Class to JVM_CONSTANT_UnresolvedClass
-    // This will make verification happy.
-
-    int old_i;  // index into old_cp
-
-    // index zero (0) is not used in constantPools
-    for (old_i = 1; old_i < old_cp->length(); old_i++) {
-      // leave debugging crumb
-      jbyte old_tag = old_cp->tag_at(old_i).value();
-      switch (old_tag) {
-      case JVM_CONSTANT_Class:
-      case JVM_CONSTANT_UnresolvedClass:
-        // revert the copy to JVM_CONSTANT_UnresolvedClass
-        // May be resolving while calling this so do the same for
-        // JVM_CONSTANT_UnresolvedClass (klass_name_at() deals with transition)
-        (*merge_cp_p)->unresolved_klass_at_put(old_i,
-          old_cp->klass_name_at(old_i));
-        break;
-
-      case JVM_CONSTANT_Double:
-      case JVM_CONSTANT_Long:
-        // just copy the entry to *merge_cp_p, but double and long take
-        // two constant pool entries
-        constantPoolOopDesc::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
-        old_i++;
-        break;
-
-      default:
-        // just copy the entry to *merge_cp_p
-        constantPoolOopDesc::copy_entry_to(old_cp, old_i, *merge_cp_p, old_i, CHECK_0);
-        break;
-      }
-    } // end for each old_cp entry
-
-    // We don't need to sanity check that *merge_cp_length_p is within
-    // *merge_cp_p bounds since we have the minimum on-entry check above.
-    (*merge_cp_length_p) = old_i;
-  }
-
-  // merge_cp_len should be the same as old_cp->length() at this point
-  // so this trace message is really a "warm-and-breathing" message.
-  RC_TRACE_WITH_THREAD(0x00020000, THREAD,
-    ("after pass 0: merge_cp_len=%d", *merge_cp_length_p));
-
-  int scratch_i;  // index into scratch_cp
-  {
-    // Pass 1a:
-    // Compare scratch_cp entries to the old_cp entries that we have
-    // already copied to *merge_cp_p. In this pass, we are eliminating
-    // exact duplicates (matching entry at same index) so we only
-    // compare entries in the common indice range.
-    int increment = 1;
-    int pass1a_length = MIN2(old_cp->length(), scratch_cp->length());
-    for (scratch_i = 1; scratch_i < pass1a_length; scratch_i += increment) {
-      switch (scratch_cp->tag_at(scratch_i).value()) {
-      case JVM_CONSTANT_Double:
-      case JVM_CONSTANT_Long:
-        // double and long take two constant pool entries
-        increment = 2;
-        break;
-
-      default:
-        increment = 1;
-        break;
-      }
-
-      bool match = scratch_cp->compare_entry_to(scratch_i, *merge_cp_p,
-        scratch_i, CHECK_0);
-      if (match) {
-        // found a match at the same index so nothing more to do
-        continue;
-      } else if (is_unresolved_class_mismatch(scratch_cp, scratch_i,
-                                              *merge_cp_p, scratch_i)) {
-        // The mismatch in compare_entry_to() above is because of a
-        // resolved versus unresolved class entry at the same index
-        // with the same string value. Since Pass 0 reverted any
-        // class entries to unresolved class entries in *merge_cp_p,
-        // we go with the unresolved class entry.
-        continue;
-      } else if (is_unresolved_string_mismatch(scratch_cp, scratch_i,
-                                               *merge_cp_p, scratch_i)) {
-        // The mismatch in compare_entry_to() above is because of a
-        // resolved versus unresolved string entry at the same index
-        // with the same string value. We can live with whichever
-        // happens to be at scratch_i in *merge_cp_p.
-        continue;
-      }
-
-      int found_i = scratch_cp->find_matching_entry(scratch_i, *merge_cp_p,
-        CHECK_0);
-      if (found_i != 0) {
-        guarantee(found_i != scratch_i,
-          "compare_entry_to() and find_matching_entry() do not agree");
-
-        // Found a matching entry somewhere else in *merge_cp_p so
-        // just need a mapping entry.
-        map_index(scratch_cp, scratch_i, found_i);
-        continue;
-      }
-
-      // The find_matching_entry() call above could fail to find a match
-      // due to a resolved versus unresolved class or string entry situation
-      // like we solved above with the is_unresolved_*_mismatch() calls.
-      // However, we would have to call is_unresolved_*_mismatch() over
-      // all of *merge_cp_p (potentially) and that doesn't seem to be
-      // worth the time.
-
-      // No match found so we have to append this entry and any unique
-      // referenced entries to *merge_cp_p.
-      append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
-        CHECK_0);
-    }
-  }
-
-  RC_TRACE_WITH_THREAD(0x00020000, THREAD,
-    ("after pass 1a: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
-    *merge_cp_length_p, scratch_i, _index_map_count));
-
-  if (scratch_i < scratch_cp->length()) {
-    // Pass 1b:
-    // old_cp is smaller than scratch_cp so there are entries in
-    // scratch_cp that we have not yet processed. We take care of
-    // those now.
-    int increment = 1;
-    for (; scratch_i < scratch_cp->length(); scratch_i += increment) {
-      switch (scratch_cp->tag_at(scratch_i).value()) {
-      case JVM_CONSTANT_Double:
-      case JVM_CONSTANT_Long:
-        // double and long take two constant pool entries
-        increment = 2;
-        break;
-
-      default:
-        increment = 1;
-        break;
-      }
-
-      int found_i =
-        scratch_cp->find_matching_entry(scratch_i, *merge_cp_p, CHECK_0);
-      if (found_i != 0) {
-        // Found a matching entry somewhere else in *merge_cp_p so
-        // just need a mapping entry.
-        map_index(scratch_cp, scratch_i, found_i);
-        continue;
-      }
-
-      // No match found so we have to append this entry and any unique
-      // referenced entries to *merge_cp_p.
-      append_entry(scratch_cp, scratch_i, merge_cp_p, merge_cp_length_p,
-        CHECK_0);
-    }
-
-    RC_TRACE_WITH_THREAD(0x00020000, THREAD,
-      ("after pass 1b: merge_cp_len=%d, scratch_i=%d, index_map_len=%d",
-      *merge_cp_length_p, scratch_i, _index_map_count));
-  }
-
-  return true;
-} // end merge_constant_pools()
-
-
-// Merge constant pools between the_class and scratch_class and
-// potentially rewrite bytecodes in scratch_class to use the merged
-// constant pool.
-jvmtiError VM_RedefineClasses::merge_cp_and_rewrite(
-             instanceKlassHandle the_class, instanceKlassHandle scratch_class,
-             TRAPS) {
-  // worst case merged constant pool length is old and new combined
-  int merge_cp_length = the_class->constants()->length()
-        + scratch_class->constants()->length();
-
-  constantPoolHandle old_cp(THREAD, the_class->constants());
-  constantPoolHandle scratch_cp(THREAD, scratch_class->constants());
-
-  // Constant pools are not easily reused so we allocate a new one
-  // each time.
-  // merge_cp is created unsafe for concurrent GC processing.  It
-  // should be marked safe before discarding it. Even though
-  // garbage,  if it crosses a card boundary, it may be scanned
-  // in order to find the start of the first complete object on the card.
-  constantPoolHandle merge_cp(THREAD,
-    oopFactory::new_constantPool(merge_cp_length,
-                                 oopDesc::IsUnsafeConc,
-                                 THREAD));
-  int orig_length = old_cp->orig_length();
-  if (orig_length == 0) {
-    // This old_cp is an actual original constant pool. We save
-    // the original length in the merged constant pool so that
-    // merge_constant_pools() can be more efficient. If a constant
-    // pool has a non-zero orig_length() value, then that constant
-    // pool was created by a merge operation in RedefineClasses.
-    merge_cp->set_orig_length(old_cp->length());
-  } else {
-    // This old_cp is a merged constant pool from a previous
-    // RedefineClasses() calls so just copy the orig_length()
-    // value.
-    merge_cp->set_orig_length(old_cp->orig_length());
-  }
-
-  ResourceMark rm(THREAD);
-  _index_map_count = 0;
-  _index_map_p = new intArray(scratch_cp->length(), -1);
-
-  bool result = merge_constant_pools(old_cp, scratch_cp, &merge_cp,
-                  &merge_cp_length, THREAD);
-  if (!result) {
-    // The merge can fail due to memory allocation failure or due
-    // to robustness checks.
-    return JVMTI_ERROR_INTERNAL;
-  }
-
-  RC_TRACE_WITH_THREAD(0x00010000, THREAD,
-    ("merge_cp_len=%d, index_map_len=%d", merge_cp_length, _index_map_count));
-
-  if (_index_map_count == 0) {
-    // there is nothing to map between the new and merged constant pools
-
-    if (old_cp->length() == scratch_cp->length()) {
-      // The old and new constant pools are the same length and the
-      // index map is empty. This means that the three constant pools
-      // are equivalent (but not the same). Unfortunately, the new
-      // constant pool has not gone through link resolution nor have
-      // the new class bytecodes gone through constant pool cache
-      // rewriting so we can't use the old constant pool with the new
-      // class.
-
-      merge_cp()->set_is_conc_safe(true);
-      merge_cp = constantPoolHandle();  // toss the merged constant pool
-    } else if (old_cp->length() < scratch_cp->length()) {
-      // The old constant pool has fewer entries than the new constant
-      // pool and the index map is empty. This means the new constant
-      // pool is a superset of the old constant pool. However, the old
-      // class bytecodes have already gone through constant pool cache
-      // rewriting so we can't use the new constant pool with the old
-      // class.
-
-      merge_cp()->set_is_conc_safe(true);
-      merge_cp = constantPoolHandle();  // toss the merged constant pool
-    } else {
-      // The old constant pool has more entries than the new constant
-      // pool and the index map is empty. This means that both the old
-      // and merged constant pools are supersets of the new constant
-      // pool.
-
-      // Replace the new constant pool with a shrunken copy of the
-      // merged constant pool; the previous new constant pool will
-      // get GCed.
-      set_new_constant_pool(scratch_class, merge_cp, merge_cp_length, true,
-        THREAD);
-      // drop local ref to the merged constant pool
-      merge_cp()->set_is_conc_safe(true);
-      merge_cp = constantPoolHandle();
-    }
-  } else {
-    if (RC_TRACE_ENABLED(0x00040000)) {
-      // don't want to loop unless we are tracing
-      int count = 0;
-      for (int i = 1; i < _index_map_p->length(); i++) {
-        int value = _index_map_p->at(i);
-
-        if (value != -1) {
-          RC_TRACE_WITH_THREAD(0x00040000, THREAD,
-            ("index_map[%d]: old=%d new=%d", count, i, value));
-          count++;
+    void check_field(oop obj, int offset, klassOop static_type) {
+      oop field_value = obj->obj_field(offset);
+      if (field_value != NULL) {
+        // Field is not null
+        if (field_value->klass()->klass_part()->newest_version()->klass_part()->is_subtype_of(static_type)) {
+          // We are OK
+          RC_TRACE(0x00008000, ("Field value is OK (klass=%s, static_type=%s, offset=%d, dynamic_type=%s)",
+            obj->klass()->klass_part()->name()->as_C_string(),
+            static_type->klass_part()->name()->as_C_string(),
+            offset,
+            field_value->klass()->klass_part()->name()->as_C_string()));
+        } else {
+          // Failure!
+          RC_TRACE(0x00000001, ("Field value is INVALID - abort redefinition (klass=%s, static_type=%s, offset=%d, dynamic_type=%s)",
+            obj->klass()->klass_part()->name()->as_C_string(),
+            static_type->klass_part()->name()->as_C_string(),
+            offset,
+            field_value->klass()->klass_part()->name()->as_C_string()));
+          _result = false;
         }
       }
     }
-
-    // We have entries mapped between the new and merged constant pools
-    // so we have to rewrite some constant pool references.
-    if (!rewrite_cp_refs(scratch_class, THREAD)) {
-      return JVMTI_ERROR_INTERNAL;
+  };
+
+  CheckFieldTypesClosure myObjectClosure;
+
+  // make sure that heap is parsable (fills TLABs with filler objects)
+  Universe::heap()->ensure_parsability(false);  // no need to retire TLABs
+
+  // do the iteration
+  // If this operation encounters a bad object when using CMS,
+  // consider using safe_object_iterate() which avoids perm gen
+  // objects that may contain bad references.
+  Universe::heap()->object_iterate(&myObjectClosure);
+
+  // when sharing is enabled we must iterate over the shared spaces
+  if (UseSharedSpaces) {
+    GenCollectedHeap* gch = GenCollectedHeap::heap();
+    CompactingPermGenGen* gen = (CompactingPermGenGen*)gch->perm_gen();
+    gen->ro_space()->object_iterate(&myObjectClosure);
+    gen->rw_space()->object_iterate(&myObjectClosure);
+  }
+
+  return myObjectClosure.result();
+}
+
+void VM_RedefineClasses::clear_type_check_information(klassOop k) {
+  if (k->klass_part()->is_redefining()) {
+    k = k->klass_part()->old_version();
+  }
+
+  // We found an instance klass!
+  instanceKlass *cur_instance_klass = instanceKlass::cast(k);
+  cur_instance_klass->clear_type_check_information();
+}
+
+void VM_RedefineClasses::update_active_methods() {
+
+  RC_TRACE(0x00000002, ("Updating active methods"));
+  JavaThread *java_thread = Threads::first();
+  while (java_thread != NULL) {
+
+    int stack_depth = 0;
+    if (java_thread->has_last_Java_frame()) {
+
+      RC_TRACE(0x0000000400, ("checking stack of Java thread %s", java_thread->name()));
+
+      // vframes are resource allocated
+      Thread* current_thread = Thread::current();
+      ResourceMark rm(current_thread);
+      HandleMark hm(current_thread);
+
+      RegisterMap reg_map(java_thread);
+      frame f = java_thread->last_frame();
+      vframe* vf = vframe::new_vframe(&f, &reg_map, java_thread);
+      frame* last_entry_frame = NULL;
+
+      while (vf != NULL) {
+        if (vf->is_java_frame()) {
+          // java frame (interpreted, compiled, ...)
+          javaVFrame *jvf = javaVFrame::cast(vf);
+
+          if (!(jvf->method()->is_native())) {
+            int bci = jvf->bci();
+            RC_TRACE(0x00000400, ("found method: %s / bci=%d", jvf->method()->name()->as_C_string(), bci));
+            ResourceMark rm(Thread::current());
+            HandleMark hm;
+            instanceKlassHandle klass(jvf->method()->method_holder());
+
+            if (jvf->method()->new_version() != NULL && jvf->is_interpreted_frame()) {
+
+              
+              RC_TRACE(0x00000002, ("Found method that should just be updated to the newest version %s",
+                jvf->method()->name_and_sig_as_C_string()));
+
+              if (RC_TRACE_ENABLED(0x01000000)) {
+                int code_size = jvf->method()->code_size();
+                char *code_base_old = (char*)jvf->method()->code_base();
+                char *code_base_new = (char*)jvf->method()->new_version()->code_base();
+                for (int i=0; i<code_size; i++) {
+                  tty->print_cr("old=%d new=%d", *code_base_old++, *code_base_new++);
+                }
+                jvf->method()->print_codes_on(tty);
+                jvf->method()->new_version()->print_codes_on(tty);
+              }
+              
+              assert(jvf->is_interpreted_frame(), "Every frame must be interpreted!");              
+              interpretedVFrame *iframe = (interpretedVFrame *)jvf;
+
+
+              if (RC_TRACE_ENABLED(0x01000000)) {
+                constantPoolCacheOop cp_old = jvf->method()->constants()->cache();
+                tty->print_cr("old cp");
+                for (int i=0; i<cp_old->length(); i++) {
+                  cp_old->entry_at(i)->print(tty, i);
+                }
+                constantPoolCacheOop cp_new = jvf->method()->new_version()->constants()->cache();
+                tty->print_cr("new cp");
+                for (int i=0; i<cp_new->length(); i++) {
+                  cp_new->entry_at(i)->print(tty, i);
+                }
+              }
+
+              iframe->set_method(jvf->method()->new_version(), bci);
+              RC_TRACE(0x00000002, ("Updated method to newer version"));
+              assert(jvf->method()->new_version() == NULL, "must be latest version");
+
+            }
+          } 
+        }
+        vf = vf->sender();
+      }
     }
 
-    // Replace the new constant pool with a shrunken copy of the
-    // merged constant pool so now the rewritten bytecodes have
-    // valid references; the previous new constant pool will get
-    // GCed.
-    set_new_constant_pool(scratch_class, merge_cp, merge_cp_length, true,
-      THREAD);
-    merge_cp()->set_is_conc_safe(true);
+    // Advance to next thread
+    java_thread = java_thread->next();
   }
-  assert(old_cp()->is_conc_safe(), "Just checking");
-  assert(scratch_cp()->is_conc_safe(), "Just checking");
-
-  return JVMTI_ERROR_NONE;
-} // end merge_cp_and_rewrite()
-
-
-// Rewrite constant pool references in klass scratch_class.
-bool VM_RedefineClasses::rewrite_cp_refs(instanceKlassHandle scratch_class,
-       TRAPS) {
-
-  // rewrite constant pool references in the methods:
-  if (!rewrite_cp_refs_in_methods(scratch_class, THREAD)) {
-    // propagate failure back to caller
+}
+
+void VM_RedefineClasses::method_forwarding() {
+
+  int forwarding_count = 0;
+  JavaThread *java_thread = Threads::first();
+  while (java_thread != NULL) {
+
+    int stack_depth = 0;
+    if (java_thread->has_last_Java_frame()) {
+
+      RC_TRACE(0x00000400, ("checking stack of Java thread %s", java_thread->name()));
+
+      // vframes are resource allocated
+      Thread* current_thread = Thread::current();
+      ResourceMark rm(current_thread);
+      HandleMark hm(current_thread);
+
+      RegisterMap reg_map(java_thread);
+      frame f = java_thread->last_frame();
+      vframe* vf = vframe::new_vframe(&f, &reg_map, java_thread);
+      frame* last_entry_frame = NULL;
+
+      while (vf != NULL) {
+        if (vf->is_java_frame()) {
+          // java frame (interpreted, compiled, ...)
+          javaVFrame *jvf = javaVFrame::cast(vf);
+
+          if (!(jvf->method()->is_native())) {
+            RC_TRACE(0x00008000, ("found method: %s",
+              jvf->method()->name()->as_C_string()));
+            ResourceMark rm(Thread::current());
+            HandleMark hm;
+            instanceKlassHandle klass(jvf->method()->method_holder());
+            methodOop m = jvf->method();
+            int bci = jvf->bci();
+            RC_TRACE(0x00008000, ("klass redef %d",
+              klass->is_redefining()));
+
+            if (klass->new_version() != NULL && m->new_version() == NULL) {
+              RC_TRACE(0x00008000, ("found potential forwarding method: %s",
+                m->name()->as_C_string()));
+              
+              klassOop new_klass = klass->newest_version();
+              methodOop new_method = new_klass->klass_part()->lookup_method(m->name(), m->signature());
+              RC_TRACE(0x00000002, ("%d %d",
+                new_method,
+                new_method->constMethod()->has_code_section_table()));
+
+              if (new_method != NULL && new_method->constMethod()->has_code_section_table()) {
+                RC_TRACE(0x00008000, ("found code section table for method: %s",
+                  new_method->name()->as_C_string()));
+                m->set_forward_method(new_method);
+                if (new_method->max_locals() != m->max_locals()) {
+                  tty->print_cr("new_m max locals: %d old_m max locals: %d", new_method->max_locals(), m->max_locals());
+                }
+                assert(new_method->max_locals() == m->max_locals(), "number of locals must match");
+                assert(new_method->max_stack() == m->max_stack(), "number of stack values must match");
+                if (jvf->is_interpreted_frame()) {
+                  if (m->is_in_code_section(bci)) {
+                    // We must transfer now and cannot delay until next NOP.
+                    int new_bci = m->calculate_forward_bci(bci, new_method);
+                    interpretedVFrame* iframe = interpretedVFrame::cast(jvf);
+                    RC_TRACE(0x00000002, ("Transfering execution of %s to new method old_bci=%d new_bci=%d",
+                      new_method->name()->as_C_string(),
+                      bci,
+                      new_bci));
+                    iframe->set_method(new_method, new_bci);
+                  } else {
+                    RC_TRACE(0x00000002, ("Delaying method forwarding of %s because %d is not in a code section",
+                      new_method->name()->as_C_string(),
+                      bci));
+                  }
+                } else {
+                  RC_TRACE(0x00000002, ("Delaying method forwarding of %s because method is compiled",
+                    new_method->name()->as_C_string()));
+                }
+              }
+            }
+          } 
+        }
+        vf = vf->sender();
+      }
+    }
+
+    // Advance to next thread
+    java_thread = java_thread->next();
+  }
+
+  RC_TRACE(0x00000001, ("Method forwarding applied to %d methods",
+    forwarding_count));
+}
+
+bool VM_RedefineClasses::check_method_stacks() {
+
+  JavaThread *java_thread = Threads::first();
+  while (java_thread != NULL) {
+
+    int stack_depth = 0;
+    if (java_thread->has_last_Java_frame()) {
+
+      RC_TRACE(0x00000400, ("checking stack of Java thread %s", java_thread->name()));
+
+      // vframes are resource allocated
+      Thread* current_thread = Thread::current();
+      ResourceMark rm(current_thread);
+      HandleMark hm(current_thread);
+
+      RegisterMap reg_map(java_thread);
+      frame f = java_thread->last_frame();
+      vframe* vf = vframe::new_vframe(&f, &reg_map, java_thread);
+      frame* last_entry_frame = NULL;
+
+      while (vf != NULL) {
+        if (vf->is_java_frame()) {
+          // java frame (interpreted, compiled, ...)
+          javaVFrame *jvf = javaVFrame::cast(vf);
+
+          if (!(jvf->method()->is_native())) {
+            RC_TRACE(0x00000400, ("found method: %s", jvf->method()->name()->as_C_string()));
+            ResourceMark rm(Thread::current());
+            HandleMark hm;
+            instanceKlassHandle klass(jvf->method()->method_holder());
+
+            StackValueCollection *locals = jvf->locals();
+            const size_t message_buffer_len = klass->name()->utf8_length() + 1024;
+            char* message_buffer = NEW_RESOURCE_ARRAY(char, message_buffer_len);
+
+            for (int i=0; i<locals->size(); i++) {
+              StackValue *stack_value = locals->at(i);
+              if (stack_value->type() == T_OBJECT) {
+                Handle obj = stack_value->get_obj();
+                if (!obj.is_null() && obj->klass()->klass_part()->newest_version()->klass_part()->check_redefinition_flag(Klass::RemoveSuperType)) {
+                  
+                  // OK, so this is a possible failure => check local variable table, if it could be OK.
+                  bool result = false;
+                  methodOop method = jvf->method();
+                  if (method->has_localvariable_table()) {
+                    LocalVariableTableElement *elem = jvf->method()->localvariable_table_start();
+                    for (int j=0; j<method->localvariable_table_length(); j++) {
+
+                      if (elem->slot == i) {
+
+                        // Matching index found
+
+                        if (elem->start_bci <= jvf->bci() && elem->start_bci + elem->length > jvf->bci()) {
+
+                          // Also in range!!
+                          Symbol* signature = jvf->method()->constants()->symbol_at(elem->descriptor_cp_index);
+                          Symbol* klass_name = signature_to_class_name(signature);
+
+                          klassOop local_klass = SystemDictionary::find(klass_name, jvf->method()->method_holder()->klass_part()->class_loader(), jvf->method()->method_holder()->klass_part()->protection_domain(), Thread::current())->klass_part()->newest_version();
+                          klassOop cur = obj->klass()->klass_part()->newest_version();
+
+                          // Field is not null
+                          if (cur->klass_part()->newest_version()->klass_part()->is_subtype_of(local_klass)) {
+                            // We are OK
+                            RC_TRACE(0x00008000, ("Local variable value is OK (local_klass=%s, cur_klass=%s)",
+                              local_klass->klass_part()->name()->as_C_string(), cur->klass_part()->name()->as_C_string()));
+                            result = true;
+                          } else {
+                            // Failure!
+                            RC_TRACE(0x00000001, ("Local variable value is INVALID - abort redefinition (local_klass=%s, cur_klass=%s)",
+                              local_klass->klass_part()->name()->as_C_string(),
+                              cur->klass_part()->name()->as_C_string()));
+                            return false;
+                          }
+                        }
+                      }
+
+                      elem++;
+                    }
+                  } else {
+                    RC_TRACE(0x00000002, ("Method %s does not have a local variable table => abort",
+                      method->name_and_sig_as_C_string()));
+                  }
+                  
+                  if (!result) {
+                    return false;
+                  }
+
+                  RC_TRACE(0x00008000, ("Verifying class %s",
+                    jvf->method()->method_holder()->klass_part()->name()->as_C_string()));
+
+                  Symbol* exception_name;
+                  const size_t message_buffer_len = klass->name()->utf8_length() + 1024;
+                  char* message_buffer = NEW_RESOURCE_ARRAY(char, message_buffer_len);
+
+                  if (TraceRedefineClasses >= 4) {
+                    ClassVerifier::_verify_verbose = true;
+                  }
+
+                  Thread::current()->set_pretend_new_universe(true);
+                  ClassVerifier split_verifier(klass, message_buffer, message_buffer_len, Thread::current());
+                  split_verifier.verify_method(jvf->method(), Thread::current());
+                  exception_name = split_verifier.result();
+                  Thread::current()->set_pretend_new_universe(false);
+
+                  if (TraceRedefineClasses >= 4) {
+                    ClassVerifier::_verify_verbose = false;
+                  }
+
+                  if (exception_name != NULL) {
+                 
+                    RC_TRACE(0x00000001, ("Verification of class %s failed",
+                      jvf->method()->method_holder()->klass_part()->name()->as_C_string()));
+                    RC_TRACE(0x00000001, ("Exception: %s",
+                      exception_name->as_C_string()));
+                    RC_TRACE(0x00000001, ("Message: %s",
+                      message_buffer));
+                    Thread::current()->clear_pending_exception();
+                    return false;
+                  } 
+
+                }
+              }
+            }
+          } 
+        }
+        vf = vf->sender();
+      }
+    }
+
+    // Advance to next thread
+    java_thread = java_thread->next();
+  }
+
+  return true;
+}
+
+bool VM_RedefineClasses::check_method(methodOop method) {
+
+
+  return true;
+}
+
+// Warning: destroys redefinition level values of klasses.
+bool VM_RedefineClasses::check_loaded_methods() {
+
+  class CheckLoadedMethodsClosure : public ObjectClosure {
+
+  private:
+    
+    bool _result;
+    GrowableArray<klassOop> *_dangerous_klasses;
+
+  public:
+    CheckLoadedMethodsClosure(GrowableArray<klassOop> *dangerous_klasses) {
+      _result = true;
+      _dangerous_klasses = dangerous_klasses;
+    }
+
+    bool result() {
+      return _result;
+    }
+
+    bool is_class_dangerous(klassOop k) {
+      return k->klass_part()->newest_version()->klass_part()->check_redefinition_flag(Klass::RemoveSuperType);
+    }
+
+    bool can_be_affected(instanceKlass *klass) {
+
+      constantPoolOop cp = klass->constants();
+
+      Thread *THREAD = Thread::current();
+      klassOop k;
+      Symbol* symbol;
+
+      for (int i=1; i<cp->length(); i++) {
+        jbyte tag = cp->tag_at(i).value();
+        switch(tag) {
+          case JVM_CONSTANT_Long:
+          case JVM_CONSTANT_Double:
+            i++;
+            break;
+
+          case JVM_CONSTANT_Utf8:
+          case JVM_CONSTANT_Unicode:
+          case JVM_CONSTANT_Integer:
+          case JVM_CONSTANT_Float:
+          case JVM_CONSTANT_String:
+          case JVM_CONSTANT_Fieldref:
+          case JVM_CONSTANT_Methodref:
+          case JVM_CONSTANT_InterfaceMethodref:
+          case JVM_CONSTANT_ClassIndex:
+          case JVM_CONSTANT_UnresolvedString:
+          case JVM_CONSTANT_StringIndex:
+          case JVM_CONSTANT_UnresolvedClassInError:
+          case JVM_CONSTANT_Object:
+            // do nothing
+            break;
+
+          case JVM_CONSTANT_Class:
+            k = cp->klass_at(i, CHECK_(true));
+            if (is_class_dangerous(k)) {
+              RC_TRACE(0x00000002, ("Class %s is potentially affected, because at cp[%d] references class %s",
+                klass->name()->as_C_string(),
+                i,
+                k->klass_part()->name()->as_C_string()));
+              return true;
+            }
+            break;
+          
+          case JVM_CONSTANT_NameAndType:
+            symbol = cp->symbol_at(cp->signature_ref_index_at(i));
+            if (symbol->byte_at(0) == '(') {
+              // This must be a method
+              SignatureStream signatureStream(symbol);
+              while (true) {
+
+                if (signatureStream.is_array()) {
+                  Symbol* cur_signature = signatureStream.as_symbol(Thread::current());
+                  if (is_type_signature_dangerous(cur_signature)) {
+                    return true;
+                  }
+                } else if (signatureStream.is_object()) {
+                  if (is_symbol_dangerous(signatureStream.as_symbol(Thread::current()))) {
+                    return true;
+                  }
+                } 
+
+                if (signatureStream.at_return_type()) {
+                  break;
+                }
+
+                signatureStream.next();
+              }
+
+            } else if (is_type_signature_dangerous(symbol)) {
+              return true;
+            }
+            break;
+
+          case JVM_CONSTANT_UnresolvedClass:
+            symbol = cp->unresolved_klass_at(i);
+            if (is_symbol_dangerous(symbol)) {
+              return true;
+            }
+            break;
+
+          default:
+            ShouldNotReachHere();
+        }
+      }
+
+      return false;
+    }
+
+    bool is_type_signature_dangerous(Symbol* signature) {
+      // This must be a field type
+      if (FieldType::is_obj(signature)) {
+        Symbol* name = signature_to_class_name(signature);
+        if (is_symbol_dangerous(name)) {
+          return true;
+        }
+      } else if (FieldType::is_array(signature)) {
+        //jint dimension;
+        //Symbol* object_key;
+        FieldArrayInfo fd;
+        FieldType::get_array_info(signature, fd, Thread::current());
+        if (is_symbol_dangerous(fd.object_key())) {
+          return true;
+        }
+      }
+      return false;
+    }
+
+    bool is_symbol_dangerous(Symbol* symbol) {
+      for (int i=0; i<_dangerous_klasses->length(); i++) {
+        if(_dangerous_klasses->at(i)->klass_part()->name() == symbol) {
+          RC_TRACE(0x00000002, ("Found constant pool index %d references class %s",
+            i,
+            symbol->as_C_string()));
+          return true;
+        }
+      }
+      return false;
+    }
+
+    virtual void do_object(oop obj) {
+
+      if (!_result) return;
+
+      klassOop klassObj = (klassOop)obj;
+      Thread *THREAD = Thread::current();
+
+      // We found an instance klass!
+      instanceKlass *klass = instanceKlass::cast(klassObj);
+      instanceKlassHandle handle(klassObj);
+
+      RC_TRACE(0x00000400, ("Check if verification is necessary for class %s major_version=%d", handle->name()->as_C_string(), handle->major_version()));
+
+      if (!can_be_affected(klass)) {
+        RC_TRACE(0x00000400, ("Skipping verification of class %s major_version=%d", handle->name()->as_C_string(), handle->major_version()));
+        return;
+      }
+
+      if (handle->major_version() < Verifier::STACKMAP_ATTRIBUTE_MAJOR_VERSION) {
+        RC_TRACE(0x00000001, ("Failing because cannot verify class %s major_version=%d", handle->name()->as_C_string(), handle->major_version()));
+        _result = false;
+        return;
+      }
+
+      RC_TRACE(0x00000001, ("Verifying class %s", handle->name()->as_C_string()));
+
+      if (!Verifier::verify(handle, Verifier::NoException, true, false, Thread::current())) {
+        
+        RC_TRACE(0x00000001, ("Verification of class %s failed", handle->name()->as_C_string()));
+        //Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
+        //RC_TRACE(0x00000002, ("exception when verifying class: '%s'", ex_name->as_C_string());
+        //PENDING_EXCEPTION->print();
+        CLEAR_PENDING_EXCEPTION;
+        _result = false;
+      } 
+
+      /*int method_count = klass->methods()->length();
+      for (int i=0; i<method_count; i++) {
+        methodOop cur_method = (methodOop)klass->methods()->obj_at(i);
+        if (!check_method(cur_method)) {
+          RC_TRACE(0x00000001, ("Failed to verify consistency of method %s of klass %s", cur_method->name()->as_C_string(), klass->name()->as_C_string());
+        }
+      }*/
+    }
+  };
+
+  // TODO: Check bytecodes in case of interface => class or class => interface etc..
+
+  GrowableArray<klassOop> dangerous_klasses;
+  for (int i=0; i<_new_classes->length(); i++) {
+    instanceKlassHandle handle = _new_classes->at(i);
+    if (handle->check_redefinition_flag(Klass::RemoveSuperType)) {
+      dangerous_klasses.append(handle());
+    }
+  }
+
+  CheckLoadedMethodsClosure checkLoadedMethodsClosure(&dangerous_klasses);
+  Thread::current()->set_pretend_new_universe(true);
+  SystemDictionary::classes_do(&checkLoadedMethodsClosure);
+  Thread::current()->set_pretend_new_universe(false);
+
+
+  return checkLoadedMethodsClosure.result();
+}
+
+bool VM_RedefineClasses::check_type_consistency() {
+
+  Universe::set_verify_in_progress(true);
+
+  SystemDictionary::classes_do(calculate_type_check_information);
+  bool result = check_field_value_types();
+  SystemDictionary::classes_do(clear_type_check_information);
+  if (!result) {
+    RC_TRACE(0x00000001, ("Aborting redefinition because of wrong field or array element value!"));
+    Universe::set_verify_in_progress(false);
     return false;
   }
 
-  // rewrite constant pool references in the class_annotations:
-  if (!rewrite_cp_refs_in_class_annotations(scratch_class, THREAD)) {
-    // propagate failure back to caller
+  result = check_method_stacks();
+  if (!result) {
+    RC_TRACE(0x00000001, ("Aborting redefinition because of wrong value on the stack"));
+    Universe::set_verify_in_progress(false);
     return false;
   }
 
-  // rewrite constant pool references in the fields_annotations:
-  if (!rewrite_cp_refs_in_fields_annotations(scratch_class, THREAD)) {
-    // propagate failure back to caller
+  result = check_loaded_methods();
+  if (!result) {
+    RC_TRACE(0x00000001, ("Aborting redefinition because of wrong loaded method"));
+    Universe::set_verify_in_progress(false);
     return false;
   }
 
-  // rewrite constant pool references in the methods_annotations:
-  if (!rewrite_cp_refs_in_methods_annotations(scratch_class, THREAD)) {
-    // propagate failure back to caller
+  RC_TRACE(0x00000001, ("Verification passed => hierarchy change is valid!"));
+  Universe::set_verify_in_progress(false);
+  return true;
+}
+
+void VM_RedefineClasses::rollback() {
+  RC_TRACE(0x00000001, ("Rolling back redefinition!"));
+  SystemDictionary::rollback_redefinition();
+
+  RC_TRACE(0x00000001, ("After rolling back system dictionary!"));
+  for (int i=0; i<_new_classes->length(); i++) {
+    SystemDictionary::remove_from_hierarchy(_new_classes->at(i));
+  }
+
+  for (int i=0; i<_new_classes->length(); i++) {
+    instanceKlassHandle new_class = _new_classes->at(i);
+    new_class->set_redefining(false);
+    new_class->old_version()->klass_part()->set_new_version(NULL);
+    new_class->set_old_version(NULL);
+  }
+
+}
+
+template <class T> void VM_RedefineClasses::do_oop_work(T* p) {
+  T heap_oop = oopDesc::load_heap_oop(p);
+  if (!oopDesc::is_null(heap_oop)) {
+    oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
+    if (obj->is_instanceKlass()) {
+      klassOop klass = (klassOop)obj;
+      // DCEVM: note: can overwrite owner of old_klass constants pool with new_klass, so we need to fix it back later
+      if (klass->new_version() != NULL && klass->new_version()->klass_part()->is_redefining()) {
+        obj = klass->klass_part()->new_version();
+        oopDesc::encode_store_heap_oop_not_null(p, obj);
+      }
+    } else if (obj->blueprint()->newest_version() == SystemDictionary::Class_klass()->klass_part()->newest_version()) {
+      // update references to java.lang.Class to point to newest version. Only update references to non-primitive
+      // java.lang.Class instances.
+      klassOop klass_oop = java_lang_Class::as_klassOop(obj);
+      if (klass_oop != NULL) {
+        if (klass_oop->new_version() != NULL && klass_oop->new_version()->klass_part()->is_redefining()) {
+          obj = klass_oop->new_version()->java_mirror();
+        } else if (klass_oop->klass_part()->is_redefining()) {
+          obj = klass_oop->java_mirror();
+        }
+        oopDesc::encode_store_heap_oop_not_null(p, obj);
+
+
+        // FIXME: DCEVM: better implementation?
+        // Starting from JDK 7 java_mirror can be kept in the regular heap. Therefore, it is possible
+        // that new java_mirror is in the young generation whereas p is in tenured generation. In that
+        // case we need to run write barrier to make sure card table is properly updated. This will
+        // allow JVM to detect reference in tenured generation properly during young generation GC.
+        if (Universe::heap()->is_in_reserved(p)) {
+          if (GenCollectedHeap::heap()->is_in_young(obj)) {
+            GenRemSet* rs = GenCollectedHeap::heap()->rem_set();
+            assert(rs->rs_kind() == GenRemSet::CardTable, "Wrong rem set kind.");
+            CardTableRS* _rs = (CardTableRS*)rs;
+            _rs->inline_write_ref_field_gc(p, obj);
+          }
+        }
+      }
+    }
+  }
+}
+
+void VM_RedefineClasses::swap_marks(oop first, oop second) {
+  markOop first_mark = first->mark();
+  markOop second_mark = second->mark();
+  first->set_mark(second_mark);
+  second->set_mark(first_mark);
+}
+
+void VM_RedefineClasses::doit() {
+  Thread *thread = Thread::current();
+
+  RC_TRACE(0x00000001, ("Entering doit!"));
+
+
+  if ((_max_redefinition_flags & Klass::RemoveSuperType) != 0) {
+
+    RC_TIMER_START(_timer_check_type);
+
+    if (!check_type_consistency()) {
+      // (tw) TODO: Rollback the class redefinition
+      rollback();
+      RC_TRACE(0x00000001, ("Detected type inconsistency!"));
+      _result = JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
+      RC_TIMER_STOP(_timer_check_type);
+      return;
+    }
+
+    RC_TIMER_STOP(_timer_check_type);
+
+  } else {
+    RC_TRACE(0x00000001, ("No type narrowing => skipping check for type inconsistency"));
+  }
+
+  if (UseMethodForwardPoints) {
+    RC_TRACE(0x00000001, ("Check stack for forwarding methods to new version"));
+    method_forwarding();
+  }
+
+  if (UseSharedSpaces) {
+    // Sharing is enabled so we remap the shared readonly space to
+    // shared readwrite, private just in case we need to redefine
+    // a shared class. We do the remap during the doit() phase of
+    // the safepoint to be safer.
+    if (!CompactingPermGenGen::remap_shared_readonly_as_readwrite()) {
+      RC_TRACE(0x00000001, ("failed to remap shared readonly space to readwrite, private"));
+      _result = JVMTI_ERROR_INTERNAL;
+      return;
+    }
+  }
+
+  RC_TIMER_START(_timer_prepare_redefinition);
+  for (int i = 0; i < _new_classes->length(); i++) {
+    redefine_single_class(_new_classes->at(i), thread);
+  }
+
+  // Deoptimize all compiled code that depends on this class
+  flush_dependent_code(instanceKlassHandle(Thread::current(), (klassOop)NULL), Thread::current());
+
+  // Adjust constantpool caches and vtables for all classes
+  // that reference methods of the evolved class.
+  SystemDictionary::classes_do(adjust_cpool_cache, Thread::current());
+
+  RC_TIMER_STOP(_timer_prepare_redefinition);
+  RC_TIMER_START(_timer_redefinition);
+
+    class ChangePointersOopClosure : public OopClosure {
+      virtual void do_oop(oop* o) {
+        do_oop_work(o);
+      }
+
+      virtual void do_oop(narrowOop* o) {
+        do_oop_work(o);
+      }
+    };
+
+    class ChangePointersObjectClosure : public ObjectClosure {
+
+    private:
+
+      OopClosure *_closure;
+      bool _needs_instance_update;
+      GrowableArray<oop> *_updated_oops;
+
+    public:
+      ChangePointersObjectClosure(OopClosure *closure) : _closure(closure), _needs_instance_update(false), _updated_oops(NULL) {}
+
+      bool needs_instance_update() {
+        return _needs_instance_update;
+      }
+
+      GrowableArray<oop> *updated_oops() { return _updated_oops; }
+
+      virtual void do_object(oop obj) {
+        if (!obj->is_instanceKlass()) {
+          obj->oop_iterate(_closure);
+          
+          if (obj->blueprint()->is_redefining()) {
+
+            if (obj->blueprint()->check_redefinition_flag(Klass::HasInstanceTransformer)) {
+              if (_updated_oops == NULL) {
+                _updated_oops = new (ResourceObj::C_HEAP) GrowableArray<oop>(100, true);
+              }
+              _updated_oops->append(obj);
+            }
+
+            if(obj->blueprint()->update_information() != NULL || obj->is_perm()) {
+
+              assert(obj->blueprint()->old_version() != NULL, "must have old version");
+              obj->set_klass_no_check(obj->blueprint()->old_version());
+
+              if (obj->size() != obj->size_given_klass(obj->blueprint()->new_version()->klass_part()) || obj->is_perm()) {
+                // We need an instance update => set back to old klass
+                _needs_instance_update = true;
+
+              } else {
+                MarkSweep::update_fields(obj, obj);
+                assert(obj->blueprint()->is_redefining(), "update fields resets the klass");
+              }
+            }
+          }
+
+        } else {
+          instanceKlass *klass = instanceKlass::cast((klassOop)obj);
+          if (klass->is_redefining()) {
+            // DCEVM: We need to restorte constants pool owner which was updated by do_oop_work
+            instanceKlass* old_klass = instanceKlass::cast(klass->old_version());
+            old_klass->constants()->set_pool_holder(klass->old_version());
+ 
+            // Initialize the new class! Special static initialization that does not execute the
+            // static constructor but copies static field values from the old class if name
+            // and signature of a static field match.
+            klass->initialize_redefined_class();
+          }
+          // idubrov: FIXME: we probably don't need that since oop's will be visited in a regular way...
+          // idubrov: need to check if there is a test to verify that fields referencing class being updated
+          // idubrov: will get new version of that class
+          //klass->iterate_static_fields(_closure);
+        }
+      }
+    };
+
+    ChangePointersOopClosure oopClosure;
+    ChangePointersObjectClosure objectClosure(&oopClosure);
+
+    {
+      SharedHeap::heap()->gc_prologue(true);
+      Universe::root_oops_do(&oopClosure);
+      Universe::heap()->object_iterate(&objectClosure);
+      SharedHeap::heap()->gc_epilogue(false);
+    }
+
+    // Swap marks to have same hashcodes
+    for (int i=0; i<_new_classes->length(); i++) {
+      swap_marks(_new_classes->at(i)(), _new_classes->at(i)->old_version());
+      swap_marks(_new_classes->at(i)->java_mirror(), _new_classes->at(i)->old_version()->java_mirror());
+    }
+
+    _updated_oops = objectClosure.updated_oops();
+
+  if (objectClosure.needs_instance_update()){
+
+    // Do a full garbage collection to update the instance sizes accordingly
+    RC_TRACE(0x00000001, ("Before performing full GC!"));
+    Universe::set_redefining_gc_run(true);
+    JvmtiGCMarker jgcm;
+    notify_gc_begin(true);
+    Universe::heap()->collect_as_vm_thread(GCCause::_heap_inspection);
+    notify_gc_end();
+    Universe::set_redefining_gc_run(false);
+    RC_TRACE(0x00000001, ("GC done!"));
+  }
+
+
+  if (RC_TRACE_ENABLED(0x00000001)) {
+    if (_updated_oops != NULL) {
+      RC_TRACE(0x00000001, ("%d object(s) updated!", _updated_oops->length()));
+    } else {
+      RC_TRACE(0x00000001, ("No objects updated!"));
+    }
+  }
+
+  // Unmark klassOops as "redefining"
+  for (int i=0; i<_new_classes->length(); i++) {
+    klassOop cur = _new_classes->at(i)();
+    _new_classes->at(i)->set_redefining(false);
+    _new_classes->at(i)->clear_update_information();
+    _new_classes->at(i)->update_supers_to_newest_version();
+
+    if (((instanceKlass *)cur->klass_part()->old_version()->klass_part())->array_klasses() != NULL) {
+      update_array_classes_to_newest_version(((instanceKlass *)cur->klass_part()->old_version()->klass_part())->array_klasses());
+
+      // Transfer the array classes, otherwise we might get cast exceptions when casting array types.
+      ((instanceKlass*)cur->klass_part())->set_array_klasses(((instanceKlass*)cur->klass_part()->old_version()->klass_part())->array_klasses());
+
+      oop new_mirror = _new_classes->at(i)->java_mirror();
+      oop old_mirror = _new_classes->at(i)->old_version()->java_mirror();
+      java_lang_Class::set_array_klass(new_mirror, java_lang_Class::array_klass(old_mirror));
+
+      // Transfer init state
+      instanceKlass::ClassState state = instanceKlass::cast(cur->old_version())->init_state();
+      if (state > instanceKlass::linked) {
+        instanceKlass::cast(cur)->call_class_initializer(thread);
+      }
+    }
+  }
+
+  for (int i=T_BOOLEAN; i<=T_LONG; i++) {
+    update_array_classes_to_newest_version(Universe::typeArrayKlassObj((BasicType)i));
+  }
+
+  // Disable any dependent concurrent compilations
+  SystemDictionary::notice_modification();
+
+  // Set flag indicating that some invariants are no longer true.
+  // See jvmtiExport.hpp for detailed explanation.
+  JvmtiExport::set_has_redefined_a_class();
+
+  // Clean up caches in the compiler interface and compiler threads
+  CompileBroker::cleanup_after_redefinition();
+
+#ifdef ASSERT
+
+  // Universe::verify();
+  // JNIHandles::verify();
+
+  SystemDictionary::classes_do(check_class, thread);
+#endif
+
+  update_active_methods();
+  RC_TIMER_STOP(_timer_redefinition);
+
+}
+
+void VM_RedefineClasses::update_array_classes_to_newest_version(klassOop smallest_dimension) {
+
+  arrayKlass *curArrayKlass = arrayKlass::cast(smallest_dimension);
+  assert(curArrayKlass->lower_dimension() == NULL, "argument must be smallest dimension");
+
+
+  while (curArrayKlass != NULL) {
+    klassOop higher_dimension = curArrayKlass->higher_dimension();
+    klassOop lower_dimension = curArrayKlass->lower_dimension();
+    curArrayKlass->update_supers_to_newest_version();
+
+    curArrayKlass = NULL;
+    if (higher_dimension != NULL) {
+      curArrayKlass = arrayKlass::cast(higher_dimension);
+    }
+  }
+
+}
+
+void VM_RedefineClasses::doit_epilogue() {
+
+  RC_TIMER_START(_timer_vm_op_epilogue);
+
+  unlock_threads();
+
+  ResourceMark mark;
+
+  VM_GC_Operation::doit_epilogue();
+  RC_TRACE(0x00000001, ("GC Operation epilogue finished! "));
+
+  GrowableArray<methodHandle> instanceTransformerMethods;
+
+  // Call static transformers
+  for (int i=0; i<_new_classes->length(); i++) {
+    
+    instanceKlassHandle klass = _new_classes->at(i);
+    
+    // Find instance transformer method
+
+    if (klass->check_redefinition_flag(Klass::HasInstanceTransformer)) {
+
+      RC_TRACE(0x00008000, ("Call instance transformer of %s instance", klass->name()->as_C_string()));
+      klassOop cur_klass = klass();
+      while (cur_klass != NULL) {
+        methodOop method = ((instanceKlass*)cur_klass->klass_part())->find_method(vmSymbols::transformer_name(), vmSymbols::void_method_signature());
+        if (method != NULL) {
+          methodHandle instanceTransformerMethod(method);
+          instanceTransformerMethods.append(instanceTransformerMethod);
+          break;
+        } else {
+          cur_klass = cur_klass->klass_part()->super();
+        }
+      }
+      assert(cur_klass != NULL, "must have instance transformer method");
+    } else {
+      instanceTransformerMethods.append(methodHandle(Thread::current(), NULL));
+    }
+  }
+
+
+  // Call instance transformers
+  if (_updated_oops != NULL) {
+
+    for (int i=0; i<_updated_oops->length(); i++) {
+      assert(_updated_oops->at(i) != NULL, "must not be null!");
+      Handle cur(_updated_oops->at(i));
+      instanceKlassHandle klass(cur->klass());
+
+      if (klass->check_redefinition_flag(Klass::HasInstanceTransformer)) {
+
+        methodHandle method = instanceTransformerMethods.at(klass->redefinition_index());
+
+        RC_TRACE(0x00008000, ("executing transformer method"));
+        
+        Thread *__the_thread__ = Thread::current();
+        JavaValue result(T_VOID);
+        JavaCallArguments args(cur);
+        JavaCalls::call(&result,
+          method,
+          &args,
+          THREAD);
+
+        // TODO: What to do with an exception here?
+        if (HAS_PENDING_EXCEPTION) {
+          Symbol* ex_name = PENDING_EXCEPTION->klass()->klass_part()->name();
+          RC_TRACE(0x00000002, ("exception when executing transformer: '%s'",
+            ex_name->as_C_string()));
+          CLEAR_PENDING_EXCEPTION;
+        }
+      }
+    }
+
+    delete _updated_oops;
+    _updated_oops = NULL;
+  }
+
+  // Free the array of scratch classes
+  delete _new_classes;
+  _new_classes = NULL;
+  RC_TRACE(0x00000001, ("Redefinition finished!"));
+
+  RC_TIMER_STOP(_timer_vm_op_epilogue);
+}
+
+bool VM_RedefineClasses::is_modifiable_class(oop klass_mirror) {
+  // classes for primitives cannot be redefined
+  if (java_lang_Class::is_primitive(klass_mirror)) {
     return false;
   }
-
-  // rewrite constant pool references in the methods_parameter_annotations:
-  if (!rewrite_cp_refs_in_methods_parameter_annotations(scratch_class,
-         THREAD)) {
-    // propagate failure back to caller
+  klassOop the_class_oop = java_lang_Class::as_klassOop(klass_mirror);
+  // classes for arrays cannot be redefined
+  if (the_class_oop == NULL || !Klass::cast(the_class_oop)->oop_is_instance()) {
     return false;
   }
-
-  // rewrite constant pool references in the methods_default_annotations:
-  if (!rewrite_cp_refs_in_methods_default_annotations(scratch_class,
-         THREAD)) {
-    // propagate failure back to caller
-    return false;
+  return true;
+}
+
+#ifdef ASSERT
+
+void VM_RedefineClasses::verify_classes(klassOop k_oop_latest, oop initiating_loader, TRAPS) {
+  klassOop k_oop = k_oop_latest;
+  while (k_oop != NULL) {
+
+    instanceKlassHandle k_handle(THREAD, k_oop);
+    Verifier::verify(k_handle, Verifier::ThrowException, true, true, THREAD);
+    k_oop = k_oop->klass_part()->old_version();
   }
-
-  return true;
-} // end rewrite_cp_refs()
-
-
-// Rewrite constant pool references in the methods.
-bool VM_RedefineClasses::rewrite_cp_refs_in_methods(
-       instanceKlassHandle scratch_class, TRAPS) {
-
-  objArrayHandle methods(THREAD, scratch_class->methods());
-
-  if (methods.is_null() || methods->length() == 0) {
-    // no methods so nothing to do
-    return true;
-  }
-
-  // rewrite constant pool references in the methods:
-  for (int i = methods->length() - 1; i >= 0; i--) {
-    methodHandle method(THREAD, (methodOop)methods->obj_at(i));
-    methodHandle new_method;
-    rewrite_cp_refs_in_method(method, &new_method, CHECK_false);
-    if (!new_method.is_null()) {
-      // the method has been replaced so save the new method version
-      methods->obj_at_put(i, new_method());
+}
+
+#endif
+
+// Rewrite faster byte-codes back to their slower equivalent. Undoes rewriting happening in templateTable_xxx.cpp
+// The reason is that once we zero cpool caches, we need to re-resolve all entries again. Faster bytecodes do not
+// do that, they assume that cache entry is resolved already.
+static void unpatch_bytecode(methodOop method) {
+  RawBytecodeStream bcs(method);
+  Bytecodes::Code code;
+  Bytecodes::Code java_code;
+  while (!bcs.is_last_bytecode()) {
+    code = bcs.raw_next();
+    address bcp = bcs.bcp();
+
+    if (code == Bytecodes::_breakpoint) {
+      int bci = method->bci_from(bcp);
+      code = method->orig_bytecode_at(bci);
+      java_code = Bytecodes::java_code(code);
+      if (code != java_code &&
+           (java_code == Bytecodes::_getfield ||
+            java_code == Bytecodes::_putfield ||
+            java_code == Bytecodes::_aload_0)) {
+        // Let breakpoint table handling unpatch bytecode
+        method->set_orig_bytecode_at(bci, java_code);
+      }
+    } else {
+      java_code = Bytecodes::java_code(code);
+      if (code != java_code &&
+           (java_code == Bytecodes::_getfield ||
+            java_code == Bytecodes::_putfield ||
+            java_code == Bytecodes::_aload_0)) {
+        *bcp = java_code;
+      }
+    }
+
+    // Additionally, we need to unpatch bytecode at bcp+1 for fast_xaccess (which would be fast field access)
+    if (code == Bytecodes::_fast_iaccess_0 || code == Bytecodes::_fast_aaccess_0 || code == Bytecodes::_fast_faccess_0) {
+      Bytecodes::Code code2 = Bytecodes::code_or_bp_at(bcp + 1);
+      assert(code2 == Bytecodes::_fast_igetfield ||
+             code2 == Bytecodes::_fast_agetfield ||
+             code2 == Bytecodes::_fast_fgetfield, "");
+      *(bcp + 1) = Bytecodes::java_code(code2);
     }
   }
-
-  return true;
 }
 
-
-// Rewrite constant pool references in the specific method. This code
-// was adapted from Rewriter::rewrite_method().
-void VM_RedefineClasses::rewrite_cp_refs_in_method(methodHandle method,
-       methodHandle *new_method_p, TRAPS) {
-
-  *new_method_p = methodHandle();  // default is no new method
-
-  // We cache a pointer to the bytecodes here in code_base. If GC
-  // moves the methodOop, then the bytecodes will also move which
-  // will likely cause a crash. We create a No_Safepoint_Verifier
-  // object to detect whether we pass a possible safepoint in this
-  // code block.
-  No_Safepoint_Verifier nsv;
-
-  // Bytecodes and their length
-  address code_base = method->code_base();
-  int code_length = method->code_size();
-
-  int bc_length;
-  for (int bci = 0; bci < code_length; bci += bc_length) {
-    address bcp = code_base + bci;
-    Bytecodes::Code c = (Bytecodes::Code)(*bcp);
-
-    bc_length = Bytecodes::length_for(c);
-    if (bc_length == 0) {
-      // More complicated bytecodes report a length of zero so
-      // we have to try again a slightly different way.
-      bc_length = Bytecodes::length_at(method(), bcp);
-    }
-
-    assert(bc_length != 0, "impossible bytecode length");
-
-    switch (c) {
-      case Bytecodes::_ldc:
-      {
-        int cp_index = *(bcp + 1);
-        int new_index = find_new_index(cp_index);
-
-        if (StressLdcRewrite && new_index == 0) {
-          // If we are stressing ldc -> ldc_w rewriting, then we
-          // always need a new_index value.
-          new_index = cp_index;
-        }
-        if (new_index != 0) {
-          // the original index is mapped so we have more work to do
-          if (!StressLdcRewrite && new_index <= max_jubyte) {
-            // The new value can still use ldc instead of ldc_w
-            // unless we are trying to stress ldc -> ldc_w rewriting
-            RC_TRACE_WITH_THREAD(0x00080000, THREAD,
-              ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
-              bcp, cp_index, new_index));
-            *(bcp + 1) = new_index;
-          } else {
-            RC_TRACE_WITH_THREAD(0x00080000, THREAD,
-              ("%s->ldc_w@" INTPTR_FORMAT " old=%d, new=%d",
-              Bytecodes::name(c), bcp, cp_index, new_index));
-            // the new value needs ldc_w instead of ldc
-            u_char inst_buffer[4]; // max instruction size is 4 bytes
-            bcp = (address)inst_buffer;
-            // construct new instruction sequence
-            *bcp = Bytecodes::_ldc_w;
-            bcp++;
-            // Rewriter::rewrite_method() does not rewrite ldc -> ldc_w.
-            // See comment below for difference between put_Java_u2()
-            // and put_native_u2().
-            Bytes::put_Java_u2(bcp, new_index);
-
-            Relocator rc(method, NULL /* no RelocatorListener needed */);
-            methodHandle m;
-            {
-              Pause_No_Safepoint_Verifier pnsv(&nsv);
-
-              // ldc is 2 bytes and ldc_w is 3 bytes
-              m = rc.insert_space_at(bci, 3, inst_buffer, THREAD);
-              if (m.is_null() || HAS_PENDING_EXCEPTION) {
-                guarantee(false, "insert_space_at() failed");
-              }
-            }
-
-            // return the new method so that the caller can update
-            // the containing class
-            *new_method_p = method = m;
-            // switch our bytecode processing loop from the old method
-            // to the new method
-            code_base = method->code_base();
-            code_length = method->code_size();
-            bcp = code_base + bci;
-            c = (Bytecodes::Code)(*bcp);
-            bc_length = Bytecodes::length_for(c);
-            assert(bc_length != 0, "sanity check");
-          } // end we need ldc_w instead of ldc
-        } // end if there is a mapped index
-      } break;
-
-      // these bytecodes have a two-byte constant pool index
-      case Bytecodes::_anewarray      : // fall through
-      case Bytecodes::_checkcast      : // fall through
-      case Bytecodes::_getfield       : // fall through
-      case Bytecodes::_getstatic      : // fall through
-      case Bytecodes::_instanceof     : // fall through
-      case Bytecodes::_invokeinterface: // fall through
-      case Bytecodes::_invokespecial  : // fall through
-      case Bytecodes::_invokestatic   : // fall through
-      case Bytecodes::_invokevirtual  : // fall through
-      case Bytecodes::_ldc_w          : // fall through
-      case Bytecodes::_ldc2_w         : // fall through
-      case Bytecodes::_multianewarray : // fall through
-      case Bytecodes::_new            : // fall through
-      case Bytecodes::_putfield       : // fall through
-      case Bytecodes::_putstatic      :
-      {
-        address p = bcp + 1;
-        int cp_index = Bytes::get_Java_u2(p);
-        int new_index = find_new_index(cp_index);
-        if (new_index != 0) {
-          // the original index is mapped so update w/ new value
-          RC_TRACE_WITH_THREAD(0x00080000, THREAD,
-            ("%s@" INTPTR_FORMAT " old=%d, new=%d", Bytecodes::name(c),
-            bcp, cp_index, new_index));
-          // Rewriter::rewrite_method() uses put_native_u2() in this
-          // situation because it is reusing the constant pool index
-          // location for a native index into the constantPoolCache.
-          // Since we are updating the constant pool index prior to
-          // verification and constantPoolCache initialization, we
-          // need to keep the new index in Java byte order.
-          Bytes::put_Java_u2(p, new_index);
-        }
-      } break;
-    }
-  } // end for each bytecode
-} // end rewrite_cp_refs_in_method()
-
-
-// Rewrite constant pool references in the class_annotations field.
-bool VM_RedefineClasses::rewrite_cp_refs_in_class_annotations(
-       instanceKlassHandle scratch_class, TRAPS) {
-
-  typeArrayHandle class_annotations(THREAD,
-    scratch_class->class_annotations());
-  if (class_annotations.is_null() || class_annotations->length() == 0) {
-    // no class_annotations so nothing to do
-    return true;
-  }
-
-  RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-    ("class_annotations length=%d", class_annotations->length()));
-
-  int byte_i = 0;  // byte index into class_annotations
-  return rewrite_cp_refs_in_annotations_typeArray(class_annotations, byte_i,
-           THREAD);
-}
-
-
-// Rewrite constant pool references in an annotations typeArray. This
-// "structure" is adapted from the RuntimeVisibleAnnotations_attribute
-// that is described in section 4.8.15 of the 2nd-edition of the VM spec:
-//
-// annotations_typeArray {
-//   u2 num_annotations;
-//   annotation annotations[num_annotations];
-// }
-//
-bool VM_RedefineClasses::rewrite_cp_refs_in_annotations_typeArray(
-       typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) {
-
-  if ((byte_i_ref + 2) > annotations_typeArray->length()) {
-    // not enough room for num_annotations field
-    RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-      ("length() is too small for num_annotations field"));
-    return false;
-  }
-
-  u2 num_annotations = Bytes::get_Java_u2((address)
-                         annotations_typeArray->byte_at_addr(byte_i_ref));
-  byte_i_ref += 2;
-
-  RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-    ("num_annotations=%d", num_annotations));
-
-  int calc_num_annotations = 0;
-  for (; calc_num_annotations < num_annotations; calc_num_annotations++) {
-    if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
-           byte_i_ref, THREAD)) {
-      RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-        ("bad annotation_struct at %d", calc_num_annotations));
-      // propagate failure back to caller
-      return false;
-    }
-  }
-  assert(num_annotations == calc_num_annotations, "sanity check");
-
-  return true;
-} // end rewrite_cp_refs_in_annotations_typeArray()
-
-
-// Rewrite constant pool references in the annotation struct portion of
-// an annotations_typeArray. This "structure" is from section 4.8.15 of
-// the 2nd-edition of the VM spec:
-//
-// struct annotation {
-//   u2 type_index;
-//   u2 num_element_value_pairs;
-//   {
-//     u2 element_name_index;
-//     element_value value;
-//   } element_value_pairs[num_element_value_pairs];
-// }
-//
-bool VM_RedefineClasses::rewrite_cp_refs_in_annotation_struct(
-       typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) {
-  if ((byte_i_ref + 2 + 2) > annotations_typeArray->length()) {
-    // not enough room for smallest annotation_struct
-    RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-      ("length() is too small for annotation_struct"));
-    return false;
-  }
-
-  u2 type_index = rewrite_cp_ref_in_annotation_data(annotations_typeArray,
-                    byte_i_ref, "mapped old type_index=%d", THREAD);
-
-  u2 num_element_value_pairs = Bytes::get_Java_u2((address)
-                                 annotations_typeArray->byte_at_addr(
-                                 byte_i_ref));
-  byte_i_ref += 2;
-
-  RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-    ("type_index=%d  num_element_value_pairs=%d", type_index,
-    num_element_value_pairs));
-
-  int calc_num_element_value_pairs = 0;
-  for (; calc_num_element_value_pairs < num_element_value_pairs;
-       calc_num_element_value_pairs++) {
-    if ((byte_i_ref + 2) > annotations_typeArray->length()) {
-      // not enough room for another element_name_index, let alone
-      // the rest of another component
-      RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-        ("length() is too small for element_name_index"));
-      return false;
-    }
-
-    u2 element_name_index = rewrite_cp_ref_in_annotation_data(
-                              annotations_typeArray, byte_i_ref,
-                              "mapped old element_name_index=%d", THREAD);
-
-    RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-      ("element_name_index=%d", element_name_index));
-
-    if (!rewrite_cp_refs_in_element_value(annotations_typeArray,
-           byte_i_ref, THREAD)) {
-      RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-        ("bad element_value at %d", calc_num_element_value_pairs));
-      // propagate failure back to caller
-      return false;
-    }
-  } // end for each component
-  assert(num_element_value_pairs == calc_num_element_value_pairs,
-    "sanity check");
-
-  return true;
-} // end rewrite_cp_refs_in_annotation_struct()
-
-
-// Rewrite a constant pool reference at the current position in
-// annotations_typeArray if needed. Returns the original constant
-// pool reference if a rewrite was not needed or the new constant
-// pool reference if a rewrite was needed.
-u2 VM_RedefineClasses::rewrite_cp_ref_in_annotation_data(
-     typeArrayHandle annotations_typeArray, int &byte_i_ref,
-     const char * trace_mesg, TRAPS) {
-
-  address cp_index_addr = (address)
-    annotations_typeArray->byte_at_addr(byte_i_ref);
-  u2 old_cp_index = Bytes::get_Java_u2(cp_index_addr);
-  u2 new_cp_index = find_new_index(old_cp_index);
-  if (new_cp_index != 0) {
-    RC_TRACE_WITH_THREAD(0x02000000, THREAD, (trace_mesg, old_cp_index));
-    Bytes::put_Java_u2(cp_index_addr, new_cp_index);
-    old_cp_index = new_cp_index;
-  }
-  byte_i_ref += 2;
-  return old_cp_index;
-}
-
-
-// Rewrite constant pool references in the element_value portion of an
-// annotations_typeArray. This "structure" is from section 4.8.15.1 of
-// the 2nd-edition of the VM spec:
-//
-// struct element_value {
-//   u1 tag;
-//   union {
-//     u2 const_value_index;
-//     {
-//       u2 type_name_index;
-//       u2 const_name_index;
-//     } enum_const_value;
-//     u2 class_info_index;
-//     annotation annotation_value;
-//     struct {
-//       u2 num_values;
-//       element_value values[num_values];
-//     } array_value;
-//   } value;
-// }
-//
-bool VM_RedefineClasses::rewrite_cp_refs_in_element_value(
-       typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS) {
-
-  if ((byte_i_ref + 1) > annotations_typeArray->length()) {
-    // not enough room for a tag let alone the rest of an element_value
-    RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-      ("length() is too small for a tag"));
-    return false;
-  }
-
-  u1 tag = annotations_typeArray->byte_at(byte_i_ref);
-  byte_i_ref++;
-  RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("tag='%c'", tag));
-
-  switch (tag) {
-    // These BaseType tag values are from Table 4.2 in VM spec:
-    case 'B':  // byte
-    case 'C':  // char
-    case 'D':  // double
-    case 'F':  // float
-    case 'I':  // int
-    case 'J':  // long
-    case 'S':  // short
-    case 'Z':  // boolean
-
-    // The remaining tag values are from Table 4.8 in the 2nd-edition of
-    // the VM spec:
-    case 's':
-    {
-      // For the above tag values (including the BaseType values),
-      // value.const_value_index is right union field.
-
-      if ((byte_i_ref + 2) > annotations_typeArray->length()) {
-        // not enough room for a const_value_index
-        RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-          ("length() is too small for a const_value_index"));
-        return false;
-      }
-
-      u2 const_value_index = rewrite_cp_ref_in_annotation_data(
-                               annotations_typeArray, byte_i_ref,
-                               "mapped old const_value_index=%d", THREAD);
-
-      RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-        ("const_value_index=%d", const_value_index));
-    } break;
-
-    case 'e':
-    {
-      // for the above tag value, value.enum_const_value is right union field
-
-      if ((byte_i_ref + 4) > annotations_typeArray->length()) {
-        // not enough room for a enum_const_value
-        RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-          ("length() is too small for a enum_const_value"));
-        return false;
-      }
-
-      u2 type_name_index = rewrite_cp_ref_in_annotation_data(
-                             annotations_typeArray, byte_i_ref,
-                             "mapped old type_name_index=%d", THREAD);
-
-      u2 const_name_index = rewrite_cp_ref_in_annotation_data(
-                              annotations_typeArray, byte_i_ref,
-                              "mapped old const_name_index=%d", THREAD);
-
-      RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-        ("type_name_index=%d  const_name_index=%d", type_name_index,
-        const_name_index));
-    } break;
-
-    case 'c':
-    {
-      // for the above tag value, value.class_info_index is right union field
-
-      if ((byte_i_ref + 2) > annotations_typeArray->length()) {
-        // not enough room for a class_info_index
-        RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-          ("length() is too small for a class_info_index"));
-        return false;
-      }
-
-      u2 class_info_index = rewrite_cp_ref_in_annotation_data(
-                              annotations_typeArray, byte_i_ref,
-                              "mapped old class_info_index=%d", THREAD);
-
-      RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-        ("class_info_index=%d", class_info_index));
-    } break;
-
-    case '@':
-      // For the above tag value, value.attr_value is the right union
-      // field. This is a nested annotation.
-      if (!rewrite_cp_refs_in_annotation_struct(annotations_typeArray,
-             byte_i_ref, THREAD)) {
-        // propagate failure back to caller
-        return false;
-      }
-      break;
-
-    case '[':
-    {
-      if ((byte_i_ref + 2) > annotations_typeArray->length()) {
-        // not enough room for a num_values field
-        RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-          ("length() is too small for a num_values field"));
-        return false;
-      }
-
-      // For the above tag value, value.array_value is the right union
-      // field. This is an array of nested element_value.
-      u2 num_values = Bytes::get_Java_u2((address)
-                        annotations_typeArray->byte_at_addr(byte_i_ref));
-      byte_i_ref += 2;
-      RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("num_values=%d", num_values));
-
-      int calc_num_values = 0;
-      for (; calc_num_values < num_values; calc_num_values++) {
-        if (!rewrite_cp_refs_in_element_value(
-               annotations_typeArray, byte_i_ref, THREAD)) {
-          RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-            ("bad nested element_value at %d", calc_num_values));
-          // propagate failure back to caller
-          return false;
-        }
-      }
-      assert(num_values == calc_num_values, "sanity check");
-    } break;
-
-    default:
-      RC_TRACE_WITH_THREAD(0x02000000, THREAD, ("bad tag=0x%x", tag));
-      return false;
-  } // end decode tag field
-
-  return true;
-} // end rewrite_cp_refs_in_element_value()
-
-
-// Rewrite constant pool references in a fields_annotations field.
-bool VM_RedefineClasses::rewrite_cp_refs_in_fields_annotations(
-       instanceKlassHandle scratch_class, TRAPS) {
-
-  objArrayHandle fields_annotations(THREAD,
-    scratch_class->fields_annotations());
-
-  if (fields_annotations.is_null() || fields_annotations->length() == 0) {
-    // no fields_annotations so nothing to do
-    return true;
-  }
-
-  RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-    ("fields_annotations length=%d", fields_annotations->length()));
-
-  for (int i = 0; i < fields_annotations->length(); i++) {
-    typeArrayHandle field_annotations(THREAD,
-      (typeArrayOop)fields_annotations->obj_at(i));
-    if (field_annotations.is_null() || field_annotations->length() == 0) {
-      // this field does not have any annotations so skip it
-      continue;
-    }
-
-    int byte_i = 0;  // byte index into field_annotations
-    if (!rewrite_cp_refs_in_annotations_typeArray(field_annotations, byte_i,
-           THREAD)) {
-      RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-        ("bad field_annotations at %d", i));
-      // propagate failure back to caller
-      return false;
-    }
-  }
-
-  return true;
-} // end rewrite_cp_refs_in_fields_annotations()
-
-
-// Rewrite constant pool references in a methods_annotations field.
-bool VM_RedefineClasses::rewrite_cp_refs_in_methods_annotations(
-       instanceKlassHandle scratch_class, TRAPS) {
-
-  objArrayHandle methods_annotations(THREAD,
-    scratch_class->methods_annotations());
-
-  if (methods_annotations.is_null() || methods_annotations->length() == 0) {
-    // no methods_annotations so nothing to do
-    return true;
-  }
-
-  RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-    ("methods_annotations length=%d", methods_annotations->length()));
-
-  for (int i = 0; i < methods_annotations->length(); i++) {
-    typeArrayHandle method_annotations(THREAD,
-      (typeArrayOop)methods_annotations->obj_at(i));
-    if (method_annotations.is_null() || method_annotations->length() == 0) {
-      // this method does not have any annotations so skip it
-      continue;
-    }
-
-    int byte_i = 0;  // byte index into method_annotations
-    if (!rewrite_cp_refs_in_annotations_typeArray(method_annotations, byte_i,
-           THREAD)) {
-      RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-        ("bad method_annotations at %d", i));
-      // propagate failure back to caller
-      return false;
-    }
-  }
-
-  return true;
-} // end rewrite_cp_refs_in_methods_annotations()
-
-
-// Rewrite constant pool references in a methods_parameter_annotations
-// field. This "structure" is adapted from the
-// RuntimeVisibleParameterAnnotations_attribute described in section
-// 4.8.17 of the 2nd-edition of the VM spec:
-//
-// methods_parameter_annotations_typeArray {
-//   u1 num_parameters;
-//   {
-//     u2 num_annotations;
-//     annotation annotations[num_annotations];
-//   } parameter_annotations[num_parameters];
-// }
-//
-bool VM_RedefineClasses::rewrite_cp_refs_in_methods_parameter_annotations(
-       instanceKlassHandle scratch_class, TRAPS) {
-
-  objArrayHandle methods_parameter_annotations(THREAD,
-    scratch_class->methods_parameter_annotations());
-
-  if (methods_parameter_annotations.is_null()
-      || methods_parameter_annotations->length() == 0) {
-    // no methods_parameter_annotations so nothing to do
-    return true;
-  }
-
-  RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-    ("methods_parameter_annotations length=%d",
-    methods_parameter_annotations->length()));
-
-  for (int i = 0; i < methods_parameter_annotations->length(); i++) {
-    typeArrayHandle method_parameter_annotations(THREAD,
-      (typeArrayOop)methods_parameter_annotations->obj_at(i));
-    if (method_parameter_annotations.is_null()
-        || method_parameter_annotations->length() == 0) {
-      // this method does not have any parameter annotations so skip it
-      continue;
-    }
-
-    if (method_parameter_annotations->length() < 1) {
-      // not enough room for a num_parameters field
-      RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-        ("length() is too small for a num_parameters field at %d", i));
-      return false;
-    }
-
-    int byte_i = 0;  // byte index into method_parameter_annotations
-
-    u1 num_parameters = method_parameter_annotations->byte_at(byte_i);
-    byte_i++;
-
-    RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-      ("num_parameters=%d", num_parameters));
-
-    int calc_num_parameters = 0;
-    for (; calc_num_parameters < num_parameters; calc_num_parameters++) {
-      if (!rewrite_cp_refs_in_annotations_typeArray(
-             method_parameter_annotations, byte_i, THREAD)) {
-        RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-          ("bad method_parameter_annotations at %d", calc_num_parameters));
-        // propagate failure back to caller
-        return false;
-      }
-    }
-    assert(num_parameters == calc_num_parameters, "sanity check");
-  }
-
-  return true;
-} // end rewrite_cp_refs_in_methods_parameter_annotations()
-
-
-// Rewrite constant pool references in a methods_default_annotations
-// field. This "structure" is adapted from the AnnotationDefault_attribute
-// that is described in section 4.8.19 of the 2nd-edition of the VM spec:
-//
-// methods_default_annotations_typeArray {
-//   element_value default_value;
-// }
-//
-bool VM_RedefineClasses::rewrite_cp_refs_in_methods_default_annotations(
-       instanceKlassHandle scratch_class, TRAPS) {
-
-  objArrayHandle methods_default_annotations(THREAD,
-    scratch_class->methods_default_annotations());
-
-  if (methods_default_annotations.is_null()
-      || methods_default_annotations->length() == 0) {
-    // no methods_default_annotations so nothing to do
-    return true;
-  }
-
-  RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-    ("methods_default_annotations length=%d",
-    methods_default_annotations->length()));
-
-  for (int i = 0; i < methods_default_annotations->length(); i++) {
-    typeArrayHandle method_default_annotations(THREAD,
-      (typeArrayOop)methods_default_annotations->obj_at(i));
-    if (method_default_annotations.is_null()
-        || method_default_annotations->length() == 0) {
-      // this method does not have any default annotations so skip it
-      continue;
-    }
-
-    int byte_i = 0;  // byte index into method_default_annotations
-
-    if (!rewrite_cp_refs_in_element_value(
-           method_default_annotations, byte_i, THREAD)) {
-      RC_TRACE_WITH_THREAD(0x02000000, THREAD,
-        ("bad default element_value at %d", i));
-      // propagate failure back to caller
-      return false;
-    }
-  }
-
-  return true;
-} // end rewrite_cp_refs_in_methods_default_annotations()
-
-
-// Rewrite constant pool references in the method's stackmap table.
-// These "structures" are adapted from the StackMapTable_attribute that
-// is described in section 4.8.4 of the 6.0 version of the VM spec
-// (dated 2005.10.26):
-// file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
-//
-// stack_map {
-//   u2 number_of_entries;
-//   stack_map_frame entries[number_of_entries];
-// }
-//
-void VM_RedefineClasses::rewrite_cp_refs_in_stack_map_table(
-       methodHandle method, TRAPS) {
-
-  if (!method->has_stackmap_table()) {
-    return;
-  }
-
-  typeArrayOop stackmap_data = method->stackmap_data();
-  address stackmap_p = (address)stackmap_data->byte_at_addr(0);
-  address stackmap_end = stackmap_p + stackmap_data->length();
-
-  assert(stackmap_p + 2 <= stackmap_end, "no room for number_of_entries");
-  u2 number_of_entries = Bytes::get_Java_u2(stackmap_p);
-  stackmap_p += 2;
-
-  RC_TRACE_WITH_THREAD(0x04000000, THREAD,
-    ("number_of_entries=%u", number_of_entries));
-
-  // walk through each stack_map_frame
-  u2 calc_number_of_entries = 0;
-  for (; calc_number_of_entries < number_of_entries; calc_number_of_entries++) {
-    // The stack_map_frame structure is a u1 frame_type followed by
-    // 0 or more bytes of data:
-    //
-    // union stack_map_frame {
-    //   same_frame;
-    //   same_locals_1_stack_item_frame;
-    //   same_locals_1_stack_item_frame_extended;
-    //   chop_frame;
-    //   same_frame_extended;
-    //   append_frame;
-    //   full_frame;
-    // }
-
-    assert(stackmap_p + 1 <= stackmap_end, "no room for frame_type");
-    // The Linux compiler does not like frame_type to be u1 or u2. It
-    // issues the following warning for the first if-statement below:
-    //
-    // "warning: comparison is always true due to limited range of data type"
-    //
-    u4 frame_type = *stackmap_p;
-    stackmap_p++;
-
-    // same_frame {
-    //   u1 frame_type = SAME; /* 0-63 */
-    // }
-    if (frame_type >= 0 && frame_type <= 63) {
-      // nothing more to do for same_frame
-    }
-
-    // same_locals_1_stack_item_frame {
-    //   u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
-    //   verification_type_info stack[1];
-    // }
-    else if (frame_type >= 64 && frame_type <= 127) {
-      rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
-        calc_number_of_entries, frame_type, THREAD);
-    }
-
-    // reserved for future use
-    else if (frame_type >= 128 && frame_type <= 246) {
-      // nothing more to do for reserved frame_types
-    }
-
-    // same_locals_1_stack_item_frame_extended {
-    //   u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
-    //   u2 offset_delta;
-    //   verification_type_info stack[1];
-    // }
-    else if (frame_type == 247) {
-      stackmap_p += 2;
-      rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
-        calc_number_of_entries, frame_type, THREAD);
-    }
-
-    // chop_frame {
-    //   u1 frame_type = CHOP; /* 248-250 */
-    //   u2 offset_delta;
-    // }
-    else if (frame_type >= 248 && frame_type <= 250) {
-      stackmap_p += 2;
-    }
-
-    // same_frame_extended {
-    //   u1 frame_type = SAME_FRAME_EXTENDED; /* 251*/
-    //   u2 offset_delta;
-    // }
-    else if (frame_type == 251) {
-      stackmap_p += 2;
-    }
-
-    // append_frame {
-    //   u1 frame_type = APPEND; /* 252-254 */
-    //   u2 offset_delta;
-    //   verification_type_info locals[frame_type - 251];
-    // }
-    else if (frame_type >= 252 && frame_type <= 254) {
-      assert(stackmap_p + 2 <= stackmap_end,
-        "no room for offset_delta");
-      stackmap_p += 2;
-      u1 len = frame_type - 251;
-      for (u1 i = 0; i < len; i++) {
-        rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
-          calc_number_of_entries, frame_type, THREAD);
-      }
-    }
-
-    // full_frame {
-    //   u1 frame_type = FULL_FRAME; /* 255 */
-    //   u2 offset_delta;
-    //   u2 number_of_locals;
-    //   verification_type_info locals[number_of_locals];
-    //   u2 number_of_stack_items;
-    //   verification_type_info stack[number_of_stack_items];
-    // }
-    else if (frame_type == 255) {
-      assert(stackmap_p + 2 + 2 <= stackmap_end,
-        "no room for smallest full_frame");
-      stackmap_p += 2;
-
-      u2 number_of_locals = Bytes::get_Java_u2(stackmap_p);
-      stackmap_p += 2;
-
-      for (u2 locals_i = 0; locals_i < number_of_locals; locals_i++) {
-        rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
-          calc_number_of_entries, frame_type, THREAD);
-      }
-
-      // Use the largest size for the number_of_stack_items, but only get
-      // the right number of bytes.
-      u2 number_of_stack_items = Bytes::get_Java_u2(stackmap_p);
-      stackmap_p += 2;
-
-      for (u2 stack_i = 0; stack_i < number_of_stack_items; stack_i++) {
-        rewrite_cp_refs_in_verification_type_info(stackmap_p, stackmap_end,
-          calc_number_of_entries, frame_type, THREAD);
-      }
-    }
-  } // end while there is a stack_map_frame
-  assert(number_of_entries == calc_number_of_entries, "sanity check");
-} // end rewrite_cp_refs_in_stack_map_table()
-
-
-// Rewrite constant pool references in the verification type info
-// portion of the method's stackmap table. These "structures" are
-// adapted from the StackMapTable_attribute that is described in
-// section 4.8.4 of the 6.0 version of the VM spec (dated 2005.10.26):
-// file:///net/quincunx.sfbay/export/gbracha/ClassFile-Java6.pdf
-//
-// The verification_type_info structure is a u1 tag followed by 0 or
-// more bytes of data:
-//
-// union verification_type_info {
-//   Top_variable_info;
-//   Integer_variable_info;
-//   Float_variable_info;
-//   Long_variable_info;
-//   Double_variable_info;
-//   Null_variable_info;
-//   UninitializedThis_variable_info;
-//   Object_variable_info;
-//   Uninitialized_variable_info;
-// }
-//
-void VM_RedefineClasses::rewrite_cp_refs_in_verification_type_info(
-       address& stackmap_p_ref, address stackmap_end, u2 frame_i,
-       u1 frame_type, TRAPS) {
-
-  assert(stackmap_p_ref + 1 <= stackmap_end, "no room for tag");
-  u1 tag = *stackmap_p_ref;
-  stackmap_p_ref++;
-
-  switch (tag) {
-  // Top_variable_info {
-  //   u1 tag = ITEM_Top; /* 0 */
-  // }
-  // verificationType.hpp has zero as ITEM_Bogus instead of ITEM_Top
-  case 0:  // fall through
-
-  // Integer_variable_info {
-  //   u1 tag = ITEM_Integer; /* 1 */
-  // }
-  case ITEM_Integer:  // fall through
-
-  // Float_variable_info {
-  //   u1 tag = ITEM_Float; /* 2 */
-  // }
-  case ITEM_Float:  // fall through
-
-  // Double_variable_info {
-  //   u1 tag = ITEM_Double; /* 3 */
-  // }
-  case ITEM_Double:  // fall through
-
-  // Long_variable_info {
-  //   u1 tag = ITEM_Long; /* 4 */
-  // }
-  case ITEM_Long:  // fall through
-
-  // Null_variable_info {
-  //   u1 tag = ITEM_Null; /* 5 */
-  // }
-  case ITEM_Null:  // fall through
-
-  // UninitializedThis_variable_info {
-  //   u1 tag = ITEM_UninitializedThis; /* 6 */
-  // }
-  case ITEM_UninitializedThis:
-    // nothing more to do for the above tag types
-    break;
-
-  // Object_variable_info {
-  //   u1 tag = ITEM_Object; /* 7 */
-  //   u2 cpool_index;
-  // }
-  case ITEM_Object:
-  {
-    assert(stackmap_p_ref + 2 <= stackmap_end, "no room for cpool_index");
-    u2 cpool_index = Bytes::get_Java_u2(stackmap_p_ref);
-    u2 new_cp_index = find_new_index(cpool_index);
-    if (new_cp_index != 0) {
-      RC_TRACE_WITH_THREAD(0x04000000, THREAD,
-        ("mapped old cpool_index=%d", cpool_index));
-      Bytes::put_Java_u2(stackmap_p_ref, new_cp_index);
-      cpool_index = new_cp_index;
-    }
-    stackmap_p_ref += 2;
-
-    RC_TRACE_WITH_THREAD(0x04000000, THREAD,
-      ("frame_i=%u, frame_type=%u, cpool_index=%d", frame_i,
-      frame_type, cpool_index));
-  } break;
-
-  // Uninitialized_variable_info {
-  //   u1 tag = ITEM_Uninitialized; /* 8 */
-  //   u2 offset;
-  // }
-  case ITEM_Uninitialized:
-    assert(stackmap_p_ref + 2 <= stackmap_end, "no room for offset");
-    stackmap_p_ref += 2;
-    break;
-
-  default:
-    RC_TRACE_WITH_THREAD(0x04000000, THREAD,
-      ("frame_i=%u, frame_type=%u, bad tag=0x%x", frame_i, frame_type, tag));
-    ShouldNotReachHere();
-    break;
-  } // end switch (tag)
-} // end rewrite_cp_refs_in_verification_type_info()
-
-
-// Change the constant pool associated with klass scratch_class to
-// scratch_cp. If shrink is true, then scratch_cp_length elements
-// are copied from scratch_cp to a smaller constant pool and the
-// smaller constant pool is associated with scratch_class.
-void VM_RedefineClasses::set_new_constant_pool(
-       instanceKlassHandle scratch_class, constantPoolHandle scratch_cp,
-       int scratch_cp_length, bool shrink, TRAPS) {
-  assert(!shrink || scratch_cp->length() >= scratch_cp_length, "sanity check");
-
-  if (shrink) {
-    // scratch_cp is a merged constant pool and has enough space for a
-    // worst case merge situation. We want to associate the minimum
-    // sized constant pool with the klass to save space.
-    constantPoolHandle smaller_cp(THREAD,
-      oopFactory::new_constantPool(scratch_cp_length,
-                                   oopDesc::IsUnsafeConc,
-                                   THREAD));
-    // preserve orig_length() value in the smaller copy
-    int orig_length = scratch_cp->orig_length();
-    assert(orig_length != 0, "sanity check");
-    smaller_cp->set_orig_length(orig_length);
-    scratch_cp->copy_cp_to(1, scratch_cp_length - 1, smaller_cp, 1, THREAD);
-    scratch_cp = smaller_cp;
-    smaller_cp()->set_is_conc_safe(true);
-  }
-
-  // attach new constant pool to klass
-  scratch_cp->set_pool_holder(scratch_class());
-
-  // attach klass to new constant pool
-  scratch_class->set_constants(scratch_cp());
-
-  int i;  // for portability
-
-  // update each field in klass to use new constant pool indices as needed
-  for (JavaFieldStream fs(scratch_class); !fs.done(); fs.next()) {
-    jshort cur_index = fs.name_index();
-    jshort new_index = find_new_index(cur_index);
-    if (new_index != 0) {
-      RC_TRACE_WITH_THREAD(0x00080000, THREAD,
-        ("field-name_index change: %d to %d", cur_index, new_index));
-      fs.set_name_index(new_index);
-    }
-    cur_index = fs.signature_index();
-    new_index = find_new_index(cur_index);
-    if (new_index != 0) {
-      RC_TRACE_WITH_THREAD(0x00080000, THREAD,
-        ("field-signature_index change: %d to %d", cur_index, new_index));
-      fs.set_signature_index(new_index);
-    }
-    cur_index = fs.initval_index();
-    new_index = find_new_index(cur_index);
-    if (new_index != 0) {
-      RC_TRACE_WITH_THREAD(0x00080000, THREAD,
-        ("field-initval_index change: %d to %d", cur_index, new_index));
-      fs.set_initval_index(new_index);
-    }
-    cur_index = fs.generic_signature_index();
-    new_index = find_new_index(cur_index);
-    if (new_index != 0) {
-      RC_TRACE_WITH_THREAD(0x00080000, THREAD,
-        ("field-generic_signature change: %d to %d", cur_index, new_index));
-      fs.set_generic_signature_index(new_index);
-    }
-  } // end for each field
-
-  // Update constant pool indices in the inner classes info to use
-  // new constant indices as needed. The inner classes info is a
-  // quadruple:
-  // (inner_class_info, outer_class_info, inner_name, inner_access_flags)
-  typeArrayOop inner_class_list = scratch_class->inner_classes();
-  int icl_length = (inner_class_list == NULL) ? 0 : inner_class_list->length();
-  if (icl_length > 0) {
-    typeArrayHandle inner_class_list_h(THREAD, inner_class_list);
-    for (int i = 0; i < icl_length;
-         i += instanceKlass::inner_class_next_offset) {
-      int cur_index = inner_class_list_h->ushort_at(i
-                        + instanceKlass::inner_class_inner_class_info_offset);
-      if (cur_index == 0) {
-        continue;  // JVM spec. allows null inner class refs so skip it
-      }
-      int new_index = find_new_index(cur_index);
-      if (new_index != 0) {
-        RC_TRACE_WITH_THREAD(0x00080000, THREAD,
-          ("inner_class_info change: %d to %d", cur_index, new_index));
-        inner_class_list_h->ushort_at_put(i
-          + instanceKlass::inner_class_inner_class_info_offset, new_index);
-      }
-      cur_index = inner_class_list_h->ushort_at(i
-                    + instanceKlass::inner_class_outer_class_info_offset);
-      new_index = find_new_index(cur_index);
-      if (new_index != 0) {
-        RC_TRACE_WITH_THREAD(0x00080000, THREAD,
-          ("outer_class_info change: %d to %d", cur_index, new_index));
-        inner_class_list_h->ushort_at_put(i
-          + instanceKlass::inner_class_outer_class_info_offset, new_index);
-      }
-      cur_index = inner_class_list_h->ushort_at(i
-                    + instanceKlass::inner_class_inner_name_offset);
-      new_index = find_new_index(cur_index);
-      if (new_index != 0) {
-        RC_TRACE_WITH_THREAD(0x00080000, THREAD,
-          ("inner_name change: %d to %d", cur_index, new_index));
-        inner_class_list_h->ushort_at_put(i
-          + instanceKlass::inner_class_inner_name_offset, new_index);
-      }
-    } // end for each inner class
-  } // end if we have inner classes
-
-  // Attach each method in klass to the new constant pool and update
-  // to use new constant pool indices as needed:
-  objArrayHandle methods(THREAD, scratch_class->methods());
-  for (i = methods->length() - 1; i >= 0; i--) {
-    methodHandle method(THREAD, (methodOop)methods->obj_at(i));
-    method->set_constants(scratch_cp());
-
-    int new_index = find_new_index(method->name_index());
-    if (new_index != 0) {
-      RC_TRACE_WITH_THREAD(0x00080000, THREAD,
-        ("method-name_index change: %d to %d", method->name_index(),
-        new_index));
-      method->set_name_index(new_index);
-    }
-    new_index = find_new_index(method->signature_index());
-    if (new_index != 0) {
-      RC_TRACE_WITH_THREAD(0x00080000, THREAD,
-        ("method-signature_index change: %d to %d",
-        method->signature_index(), new_index));
-      method->set_signature_index(new_index);
-    }
-    new_index = find_new_index(method->generic_signature_index());
-    if (new_index != 0) {
-      RC_TRACE_WITH_THREAD(0x00080000, THREAD,
-        ("method-generic_signature_index change: %d to %d",
-        method->generic_signature_index(), new_index));
-      method->set_generic_signature_index(new_index);
-    }
-
-    // Update constant pool indices in the method's checked exception
-    // table to use new constant indices as needed.
-    int cext_length = method->checked_exceptions_length();
-    if (cext_length > 0) {
-      CheckedExceptionElement * cext_table =
-        method->checked_exceptions_start();
-      for (int j = 0; j < cext_length; j++) {
-        int cur_index = cext_table[j].class_cp_index;
-        int new_index = find_new_index(cur_index);
-        if (new_index != 0) {
-          RC_TRACE_WITH_THREAD(0x00080000, THREAD,
-            ("cext-class_cp_index change: %d to %d", cur_index, new_index));
-          cext_table[j].class_cp_index = (u2)new_index;
-        }
-      } // end for each checked exception table entry
-    } // end if there are checked exception table entries
-
-    // Update each catch type index in the method's exception table
-    // to use new constant pool indices as needed. The exception table
-    // holds quadruple entries of the form:
-    //   (beg_bci, end_bci, handler_bci, klass_index)
-    const int beg_bci_offset     = 0;
-    const int end_bci_offset     = 1;
-    const int handler_bci_offset = 2;
-    const int klass_index_offset = 3;
-    const int entry_size         = 4;
-
-    typeArrayHandle ex_table (THREAD, method->exception_table());
-    int ext_length = ex_table->length();
-    assert(ext_length % entry_size == 0, "exception table format has changed");
-
-    for (int j = 0; j < ext_length; j += entry_size) {
-      int cur_index = ex_table->int_at(j + klass_index_offset);
-      int new_index = find_new_index(cur_index);
-      if (new_index != 0) {
-        RC_TRACE_WITH_THREAD(0x00080000, THREAD,
-          ("ext-klass_index change: %d to %d", cur_index, new_index));
-        ex_table->int_at_put(j + klass_index_offset, new_index);
-      }
-    } // end for each exception table entry
-
-    // Update constant pool indices in the method's local variable
-    // table to use new constant indices as needed. The local variable
-    // table hold sextuple entries of the form:
-    // (start_pc, length, name_index, descriptor_index, signature_index, slot)
-    int lvt_length = method->localvariable_table_length();
-    if (lvt_length > 0) {
-      LocalVariableTableElement * lv_table =
-        method->localvariable_table_start();
-      for (int j = 0; j < lvt_length; j++) {
-        int cur_index = lv_table[j].name_cp_index;
-        int new_index = find_new_index(cur_index);
-        if (new_index != 0) {
-          RC_TRACE_WITH_THREAD(0x00080000, THREAD,
-            ("lvt-name_cp_index change: %d to %d", cur_index, new_index));
-          lv_table[j].name_cp_index = (u2)new_index;
-        }
-        cur_index = lv_table[j].descriptor_cp_index;
-        new_index = find_new_index(cur_index);
-        if (new_index != 0) {
-          RC_TRACE_WITH_THREAD(0x00080000, THREAD,
-            ("lvt-descriptor_cp_index change: %d to %d", cur_index,
-            new_index));
-          lv_table[j].descriptor_cp_index = (u2)new_index;
-        }
-        cur_index = lv_table[j].signature_cp_index;
-        new_index = find_new_index(cur_index);
-        if (new_index != 0) {
-          RC_TRACE_WITH_THREAD(0x00080000, THREAD,
-            ("lvt-signature_cp_index change: %d to %d", cur_index, new_index));
-          lv_table[j].signature_cp_index = (u2)new_index;
-        }
-      } // end for each local variable table entry
-    } // end if there are local variable table entries
-
-    rewrite_cp_refs_in_stack_map_table(method, THREAD);
-  } // end for each method
-  assert(scratch_cp()->is_conc_safe(), "Just checking");
-} // end set_new_constant_pool()
-
-
-// Unevolving classes may point to methods of the_class directly
+// Unevolving classes may point to old methods directly
 // from their constant pool caches, itables, and/or vtables. We
 // use the SystemDictionary::classes_do() facility and this helper
-// to fix up these pointers.
+// to fix up these pointers. Additional field offsets and vtable indices
+// in the constant pool cache entries are fixed.
 //
 // Note: We currently don't support updating the vtable in
 // arrayKlassOops. See Open Issues in jvmtiRedefineClasses.hpp.
-void VM_RedefineClasses::adjust_cpool_cache_and_vtable(klassOop k_oop,
-       oop initiating_loader, TRAPS) {
+void VM_RedefineClasses::adjust_cpool_cache(klassOop k_oop_latest, oop initiating_loader, TRAPS) {
+  klassOop k_oop = k_oop_latest;
+  while (k_oop != NULL) {
+    //tty->print_cr("name=%s", k_oop->klass_part()->name()->as_C_string());
+/*
+    methodOop *matching_old_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length());
+    methodOop *matching_new_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length());
+
+    for (int i=0; i<_matching_methods_length; i++) {
+      matching_old_methods[i] = (methodOop)_old_methods->obj_at(_matching_old_methods[i]);
+      matching_new_methods[i] = (methodOop)_new_methods->obj_at(_matching_new_methods[i]);
+    }*/
+
+    Klass *k = k_oop->klass_part();
+    if (k->oop_is_instance()) {
+      HandleMark hm(THREAD);
+      instanceKlass *ik = (instanceKlass *) k;
+
+      constantPoolHandle other_cp;
+      constantPoolCacheOop cp_cache;
+
+      other_cp = constantPoolHandle(ik->constants());
+
+      for (int i=0; i<other_cp->length(); i++) {
+        if (other_cp->tag_at(i).is_klass()) {
+          klassOop klass = other_cp->klass_at(i, THREAD);
+          if (klass->klass_part()->new_version() != NULL) {
+
+            // (tw) TODO: check why/if this is necessary
+            other_cp->klass_at_put(i, klass->klass_part()->new_version());
+          }
+          klass = other_cp->klass_at(i, THREAD);
+          assert(klass->klass_part()->new_version() == NULL, "Must be new klass!");
+        }
+      }
+
+      cp_cache = other_cp->cache();
+
+      if (cp_cache != NULL) {
+        cp_cache->adjust_entries(NULL,
+          NULL,
+          0);
+      }
+
+      // If bytecode rewriting is enabled, we also need to unpatch bytecode to force resolution of zeroied entries
+      if (RewriteBytecodes) {
+        ik->methods_do(unpatch_bytecode);
+      }
+    }
+    k_oop = k_oop->klass_part()->old_version();
+  }
+}
+
+void VM_RedefineClasses::update_jmethod_ids() {
+  for (int j = 0; j < _matching_methods_length; ++j) {
+    methodOop old_method = (methodOop)_old_methods->obj_at(_matching_old_methods[j]);
+    RC_TRACE(0x00008000, ("matching method %s", old_method->name_and_sig_as_C_string()));
+    
+    jmethodID jmid = old_method->find_jmethod_id_or_null();
+    if (old_method->new_version() != NULL && jmid == NULL) {
+       // (tw) Have to create jmethodID in this case
+       jmid = old_method->jmethod_id();
+    }
+
+    if (jmid != NULL) {
+      // There is a jmethodID, change it to point to the new method
+      methodHandle new_method_h((methodOop)_new_methods->obj_at(_matching_new_methods[j]));
+      if (old_method->new_version() == NULL) {
+        methodHandle old_method_h((methodOop)_old_methods->obj_at(_matching_old_methods[j]));
+        jmethodID new_jmethod_id = JNIHandles::make_jmethod_id(old_method_h);
+        bool result = instanceKlass::cast(old_method_h->method_holder())->update_jmethod_id(old_method_h(), new_jmethod_id);
+        //RC_TRACE(0x00008000, ("Changed jmethodID for old method assigned to %d / result=%d", new_jmethod_id, result);
+        //RC_TRACE(0x00008000, ("jmethodID new method: %d jmethodID old method: %d", new_method_h->jmethod_id(), old_method->jmethod_id());
+      } else {
+        jmethodID mid = new_method_h->jmethod_id();
+        bool result = instanceKlass::cast(new_method_h->method_holder())->update_jmethod_id(new_method_h(), jmid);
+        //RC_TRACE(0x00008000, ("Changed jmethodID for new method assigned to %d / result=%d", jmid, result);
+
+      }
+      JNIHandles::change_method_associated_with_jmethod_id(jmid, new_method_h);
+      //RC_TRACE(0x00008000, ("changing method associated with jmethod id %d to %s", (int)jmid, new_method_h->name()->as_C_string());
+      assert(JNIHandles::resolve_jmethod_id(jmid) == (methodOop)_new_methods->obj_at(_matching_new_methods[j]), "should be replaced");
+      jmethodID mid = ((methodOop)_new_methods->obj_at(_matching_new_methods[j]))->jmethod_id();
+      assert(JNIHandles::resolve_non_null((jobject)mid) == new_method_h(), "must match!");
+
+      //RC_TRACE(0x00008000, ("jmethodID new method: %d jmethodID old method: %d", new_method_h->jmethod_id(), old_method->jmethod_id());
+    }
+  }
+}
+
+
+// Deoptimize all compiled code that depends on this class.
+//
+// If the can_redefine_classes capability is obtained in the onload
+// phase then the compiler has recorded all dependencies from startup.
+// In that case we need only deoptimize and throw away all compiled code
+// that depends on the class.
+//
+// If can_redefine_classes is obtained sometime after the onload
+// phase then the dependency information may be incomplete. In that case
+// the first call to RedefineClasses causes all compiled code to be
+// thrown away. As can_redefine_classes has been obtained then
+// all future compilations will record dependencies so second and
+// subsequent calls to RedefineClasses need only throw away code
+// that depends on the class.
+//
+void VM_RedefineClasses::flush_dependent_code(instanceKlassHandle k_h, TRAPS) {
+  assert_locked_or_safepoint(Compile_lock);
+
+  // All dependencies have been recorded from startup or this is a second or
+  // subsequent use of RedefineClasses
+
+  // For now deopt all
+  // (tw) TODO: Improve the dependency system such that we can safely deopt only a subset of the methods
+  if (0 && JvmtiExport::all_dependencies_are_recorded()) {
+    Universe::flush_evol_dependents_on(k_h);
+  } else {
+    CodeCache::mark_all_nmethods_for_deoptimization();
+
+    ResourceMark rm(THREAD);
+    DeoptimizationMarker dm;
+
+    // Deoptimize all activations depending on marked nmethods
+    Deoptimization::deoptimize_dependents();
+
+    // Make the dependent methods not entrant (in VM_Deoptimize they are made zombies)
+    CodeCache::make_marked_nmethods_not_entrant();
+
+    // From now on we know that the dependency information is complete
+    JvmtiExport::set_all_dependencies_are_recorded(true);
+  }
+}
+
+void VM_RedefineClasses::compute_added_deleted_matching_methods() {
+  methodOop old_method;
+  methodOop new_method;
+
+  _matching_old_methods = NEW_RESOURCE_ARRAY(int, _old_methods->length());
+  _matching_new_methods = NEW_RESOURCE_ARRAY(int, _old_methods->length());
+  _added_methods        = NEW_RESOURCE_ARRAY(int, _new_methods->length());
+  _deleted_methods      = NEW_RESOURCE_ARRAY(int, _old_methods->length());
+
+  _matching_methods_length = 0;
+  _deleted_methods_length  = 0;
+  _added_methods_length    = 0;
+
+  int nj = 0;
+  int oj = 0;
+  while (true) {
+    if (oj >= _old_methods->length()) {
+      if (nj >= _new_methods->length()) {
+        break; // we've looked at everything, done
+      }
+      // New method at the end
+      new_method = (methodOop) _new_methods->obj_at(nj);
+      _added_methods[_added_methods_length++] = nj;
+      ++nj;
+    } else if (nj >= _new_methods->length()) {
+      // Old method, at the end, is deleted
+      old_method = (methodOop) _old_methods->obj_at(oj);
+      _deleted_methods[_deleted_methods_length++] = oj;
+      ++oj;
+    } else {
+      old_method = (methodOop) _old_methods->obj_at(oj);
+      new_method = (methodOop) _new_methods->obj_at(nj);
+      if (old_method->name() == new_method->name()) {
+        if (old_method->signature() == new_method->signature()) {
+          _matching_old_methods[_matching_methods_length  ] = oj;//old_method;
+          _matching_new_methods[_matching_methods_length++] = nj;//new_method;
+          ++nj;
+          ++oj;
+        } else {
+          // added overloaded have already been moved to the end,
+          // so this is a deleted overloaded method
+          _deleted_methods[_deleted_methods_length++] = oj;//old_method;
+          ++oj;
+        }
+      } else { // names don't match
+        if (old_method->name()->fast_compare(new_method->name()) > 0) {
+          // new method
+          _added_methods[_added_methods_length++] = nj;//new_method;
+          ++nj;
+        } else {
+          // deleted method
+          _deleted_methods[_deleted_methods_length++] = oj;//old_method;
+          ++oj;
+        }
+      }
+    }
+  }
+  assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
+  assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
+  RC_TRACE(0x00008000, ("Matching methods = %d / deleted methods = %d / added methods = %d",
+    _matching_methods_length, _deleted_methods_length, _added_methods_length));
+}
+
+
+
+// Install the redefinition of a class:
+//    - house keeping (flushing breakpoints and caches, deoptimizing
+//      dependent compiled code)
+//    - adjusting constant pool caches and vtables in other classes
+void VM_RedefineClasses::redefine_single_class(instanceKlassHandle the_new_class, TRAPS) {
+
+  ResourceMark rm(THREAD);
+
+  assert(the_new_class->old_version() != NULL, "Must not be null");
+  assert(the_new_class->old_version()->klass_part()->new_version() == the_new_class(), "Must equal");
+
+  instanceKlassHandle the_old_class = instanceKlassHandle(THREAD, the_new_class->old_version());
+
+#ifndef JVMTI_KERNEL
+  // Remove all breakpoints in methods of this class
+  JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
+  jvmti_breakpoints.clearall_in_class_at_safepoint(the_old_class());
+#endif // !JVMTI_KERNEL
+
+  if (the_old_class() == Universe::reflect_invoke_cache()->klass()) {
+    // We are redefining java.lang.reflect.Method. Method.invoke() is
+    // cached and users of the cache care about each active version of
+    // the method so we have to track this previous version.
+    // Do this before methods get switched
+    Universe::reflect_invoke_cache()->add_previous_version(
+      the_old_class->method_with_idnum(Universe::reflect_invoke_cache()->method_idnum()));
+  }
+
+  _old_methods = the_old_class->methods();
+  _new_methods = the_new_class->methods();
+  _the_class_oop = the_old_class();
+  compute_added_deleted_matching_methods();
+
+  // track which methods are EMCP for add_previous_version() call below
+  
+  // (tw) TODO: Check if we need the concept of EMCP?
+   BitMap emcp_methods(_old_methods->length());
+  int emcp_method_count = 0;
+  emcp_methods.clear();  // clears 0..(length() - 1)
+  
+  // We need to mark methods as old!!
+  check_methods_and_mark_as_obsolete(&emcp_methods, &emcp_method_count);
+  update_jmethod_ids();
+
+  // keep track of previous versions of this class
+  the_new_class->add_previous_version(the_old_class, &emcp_methods,
+    emcp_method_count);
+
+  // TODO:
+  transfer_old_native_function_registrations(the_old_class);
+
+
+#ifdef ASSERT
+
+//  klassOop systemLookup1 = SystemDictionary::resolve_or_null(the_old_class->name(), the_old_class->class_loader(), the_old_class->protection_domain(), THREAD);
+//  assert(systemLookup1 == the_new_class(), "New class must be in system dictionary!");
+
+  //JNIHandles::verify();
+
+//  klassOop systemLookup = SystemDictionary::resolve_or_null(the_old_class->name(), the_old_class->class_loader(), the_old_class->protection_domain(), THREAD);
+
+//  assert(systemLookup == the_new_class(), "New class must be in system dictionary!");
+  assert(the_new_class->old_version() != NULL, "Must not be null");
+  assert(the_new_class->old_version()->klass_part()->new_version() == the_new_class(), "Must equal");
+
+  for (int i=0; i<the_new_class->methods()->length(); i++) {
+    assert(((methodOop)the_new_class->methods()->obj_at(i))->method_holder() == the_new_class(), "method holder must match!");
+  }
+
+  _old_methods->verify();
+  _new_methods->verify();
+
+  the_new_class->vtable()->verify(tty);
+  the_old_class->vtable()->verify(tty);
+
+#endif
+
+  // increment the classRedefinedCount field in the_class and in any
+  // direct and indirect subclasses of the_class
+  increment_class_counter((instanceKlass *)the_old_class()->klass_part(), THREAD);
+
+}
+
+
+void VM_RedefineClasses::check_methods_and_mark_as_obsolete(BitMap *emcp_methods, int * emcp_method_count_p) {
+    RC_TRACE(0x00008000, ("Checking matching methods for EMCP"));
+    *emcp_method_count_p = 0;
+    int obsolete_count = 0;
+    int old_index = 0;
+    for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
+      methodOop old_method = (methodOop)_old_methods->obj_at(_matching_old_methods[j]);
+      methodOop new_method = (methodOop)_new_methods->obj_at(_matching_new_methods[j]);
+      methodOop old_array_method;
+
+      // Maintain an old_index into the _old_methods array by skipping
+      // deleted methods
+      while ((old_array_method = (methodOop) _old_methods->obj_at(old_index))
+        != old_method) {
+          ++old_index;
+      }
+
+      if (MethodComparator::methods_EMCP(old_method, new_method)) {
+        // The EMCP definition from JSR-163 requires the bytecodes to be
+        // the same with the exception of constant pool indices which may
+        // differ. However, the constants referred to by those indices
+        // must be the same.
+        //
+        // We use methods_EMCP() for comparison since constant pool
+        // merging can remove duplicate constant pool entries that were
+        // present in the old method and removed from the rewritten new
+        // method. A faster binary comparison function would consider the
+        // old and new methods to be different when they are actually
+        // EMCP.
+
+        // track which methods are EMCP for add_previous_version() call
+        emcp_methods->set_bit(old_index);
+        (*emcp_method_count_p)++;
+
+        // An EMCP method is _not_ obsolete. An obsolete method has a
+        // different jmethodID than the current method. An EMCP method
+        // has the same jmethodID as the current method. Having the
+        // same jmethodID for all EMCP versions of a method allows for
+        // a consistent view of the EMCP methods regardless of which
+        // EMCP method you happen to have in hand. For example, a
+        // breakpoint set in one EMCP method will work for all EMCP
+        // versions of the method including the current one.
+
+        old_method->set_new_version(new_method);
+        new_method->set_old_version(old_method);
+
+        RC_TRACE(0x00008000, ("Found EMCP method %s", old_method->name_and_sig_as_C_string()));
+
+        // Transfer breakpoints
+        instanceKlass *ik = instanceKlass::cast(old_method->method_holder());
+        for (BreakpointInfo* bp = ik->breakpoints(); bp != NULL; bp = bp->next()) {
+          RC_TRACE(0x00000002, ("Checking breakpoint"));
+          RC_TRACE(0x00000002, ("%d / %d",
+            bp->match(old_method), bp->match(new_method)));
+          if (bp->match(old_method)) {
+            assert(bp->match(new_method), "if old method is method, then new method must match too");
+            RC_TRACE(0x00000002, ("Found a breakpoint in an old EMCP method"));
+            new_method->set_breakpoint(bp->bci());
+          }
+        }
+
+
+
+      } else {
+        // mark obsolete methods as such
+        old_method->set_is_obsolete();
+        obsolete_count++;
+
+        // With tracing we try not to "yack" too much. The position of
+        // this trace assumes there are fewer obsolete methods than
+        // EMCP methods.
+        RC_TRACE(0x00008000, ("mark %s(%s) as obsolete",
+          old_method->name()->as_C_string(),
+          old_method->signature()->as_C_string()));
+      }
+      old_method->set_is_old();
+    }
+    for (int i = 0; i < _deleted_methods_length; ++i) {
+      methodOop old_method = (methodOop)_old_methods->obj_at(_deleted_methods[i]);
+
+      //assert(old_method->vtable_index() < 0,
+      //  "cannot delete methods with vtable entries");;
+
+      // Mark all deleted methods as old and obsolete
+      old_method->set_is_old();
+      old_method->set_is_obsolete();
+      ++obsolete_count;
+      // With tracing we try not to "yack" too much. The position of
+      // this trace assumes there are fewer obsolete methods than
+      // EMCP methods.
+      RC_TRACE(0x00008000, ("mark deleted %s(%s) as obsolete",
+        old_method->name()->as_C_string(),
+        old_method->signature()->as_C_string()));
+    }
+    //assert((*emcp_method_count_p + obsolete_count) == _old_methods->length(), "sanity check");
+    RC_TRACE(0x00008000, ("EMCP_cnt=%d, obsolete_cnt=%d !", *emcp_method_count_p, obsolete_count));
+}
+
+// Increment the classRedefinedCount field in the specific instanceKlass
+// and in all direct and indirect subclasses.
+void VM_RedefineClasses::increment_class_counter(instanceKlass *ik, TRAPS) {
+  oop class_mirror = ik->java_mirror();
+  klassOop class_oop = java_lang_Class::as_klassOop(class_mirror);
+  int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
+  java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
+  RC_TRACE(0x00008000, ("updated count for class=%s to %d", ik->external_name(), new_count));
+}
+
+#ifndef PRODUCT
+void VM_RedefineClasses::check_class(klassOop k_oop, TRAPS) {
   Klass *k = k_oop->klass_part();
   if (k->oop_is_instance()) {
     HandleMark hm(THREAD);
     instanceKlass *ik = (instanceKlass *) k;
-
-    // HotSpot specific optimization! HotSpot does not currently
-    // support delegation from the bootstrap class loader to a
-    // user-defined class loader. This means that if the bootstrap
-    // class loader is the initiating class loader, then it will also
-    // be the defining class loader. This also means that classes
-    // loaded by the bootstrap class loader cannot refer to classes
-    // loaded by a user-defined class loader. Note: a user-defined
-    // class loader can delegate to the bootstrap class loader.
-    //
-    // If the current class being redefined has a user-defined class
-    // loader as its defining class loader, then we can skip all
-    // classes loaded by the bootstrap class loader.
-    bool is_user_defined =
-           instanceKlass::cast(_the_class_oop)->class_loader() != NULL;
-    if (is_user_defined && ik->class_loader() == NULL) {
-      return;
-    }
-
-    // This is a very busy routine. We don't want too much tracing
-    // printed out.
-    bool trace_name_printed = false;
-
-    // Very noisy: only enable this call if you are trying to determine
-    // that a specific class gets found by this routine.
-    // RC_TRACE macro has an embedded ResourceMark
-    // RC_TRACE_WITH_THREAD(0x00100000, THREAD,
-    //   ("adjust check: name=%s", ik->external_name()));
-    // trace_name_printed = true;
-
-    // Fix the vtable embedded in the_class and subclasses of the_class,
-    // if one exists. We discard scratch_class and we don't keep an
-    // instanceKlass around to hold obsolete methods so we don't have
-    // any other instanceKlass embedded vtables to update. The vtable
-    // holds the methodOops for virtual (but not final) methods.
-    if (ik->vtable_length() > 0 && ik->is_subtype_of(_the_class_oop)) {
-      // ik->vtable() creates a wrapper object; rm cleans it up
+    assert(ik->is_newest_version(), "must be latest version in system dictionary");
+
+    if (ik->vtable_length() > 0) {
       ResourceMark rm(THREAD);
-      ik->vtable()->adjust_method_entries(_matching_old_methods,
-                                          _matching_new_methods,
-                                          _matching_methods_length,
-                                          &trace_name_printed);
-    }
-
-    // If the current class has an itable and we are either redefining an
-    // interface or if the current class is a subclass of the_class, then
-    // we potentially have to fix the itable. If we are redefining an
-    // interface, then we have to call adjust_method_entries() for
-    // every instanceKlass that has an itable since there isn't a
-    // subclass relationship between an interface and an instanceKlass.
-    if (ik->itable_length() > 0 && (Klass::cast(_the_class_oop)->is_interface()
-        || ik->is_subclass_of(_the_class_oop))) {
-      // ik->itable() creates a wrapper object; rm cleans it up
-      ResourceMark rm(THREAD);
-      ik->itable()->adjust_method_entries(_matching_old_methods,
-                                          _matching_new_methods,
-                                          _matching_methods_length,
-                                          &trace_name_printed);
-    }
-
-    // The constant pools in other classes (other_cp) can refer to
-    // methods in the_class. We have to update method information in
-    // other_cp's cache. If other_cp has a previous version, then we
-    // have to repeat the process for each previous version. The
-    // constant pool cache holds the methodOops for non-virtual
-    // methods and for virtual, final methods.
-    //
-    // Special case: if the current class is the_class, then new_cp
-    // has already been attached to the_class and old_cp has already
-    // been added as a previous version. The new_cp doesn't have any
-    // cached references to old methods so it doesn't need to be
-    // updated. We can simply start with the previous version(s) in
-    // that case.
-    constantPoolHandle other_cp;
-    constantPoolCacheOop cp_cache;
-
-    if (k_oop != _the_class_oop) {
-      // this klass' constant pool cache may need adjustment
-      other_cp = constantPoolHandle(ik->constants());
-      cp_cache = other_cp->cache();
-      if (cp_cache != NULL) {
-        cp_cache->adjust_method_entries(_matching_old_methods,
-                                        _matching_new_methods,
-                                        _matching_methods_length,
-                                        &trace_name_printed);
+      if (!ik->vtable()->check_no_old_entries()) {
+        RC_TRACE(0x00000001, ("size of class: %d\n",
+          k_oop->size()));
+        RC_TRACE(0x00000001, ("klassVtable::check_no_old_entries failure -- OLD method found -- class: %s",
+          ik->signature_name()));
+        assert(false, "OLD method found");
       }
-    }
-    {
-      ResourceMark rm(THREAD);
-      // PreviousVersionInfo objects returned via PreviousVersionWalker
-      // contain a GrowableArray of handles. We have to clean up the
-      // GrowableArray _after_ the PreviousVersionWalker destructor
-      // has destroyed the handles.
-      {
-        // the previous versions' constant pool caches may need adjustment
-        PreviousVersionWalker pvw(ik);
-        for (PreviousVersionInfo * pv_info = pvw.next_previous_version();
-             pv_info != NULL; pv_info = pvw.next_previous_version()) {
-          other_cp = pv_info->prev_constant_pool_handle();
-          cp_cache = other_cp->cache();
-          if (cp_cache != NULL) {
-            cp_cache->adjust_method_entries(_matching_old_methods,
-                                            _matching_new_methods,
-                                            _matching_methods_length,
-                                            &trace_name_printed);
-          }
-        }
-      } // pvw is cleaned up
-    } // rm is cleaned up
-  }
-}
-
-void VM_RedefineClasses::update_jmethod_ids() {
-  for (int j = 0; j < _matching_methods_length; ++j) {
-    methodOop old_method = _matching_old_methods[j];
-    jmethodID jmid = old_method->find_jmethod_id_or_null();
-    if (jmid != NULL) {
-      // There is a jmethodID, change it to point to the new method
-      methodHandle new_method_h(_matching_new_methods[j]);
-      JNIHandles::change_method_associated_with_jmethod_id(jmid, new_method_h);
-      assert(JNIHandles::resolve_jmethod_id(jmid) == _matching_new_methods[j],
-             "should be replaced");
+
+      ik->vtable()->verify(tty, true);
     }
   }
 }
 
-void VM_RedefineClasses::check_methods_and_mark_as_obsolete(
-       BitMap *emcp_methods, int * emcp_method_count_p) {
-  *emcp_method_count_p = 0;
-  int obsolete_count = 0;
-  int old_index = 0;
-  for (int j = 0; j < _matching_methods_length; ++j, ++old_index) {
-    methodOop old_method = _matching_old_methods[j];
-    methodOop new_method = _matching_new_methods[j];
-    methodOop old_array_method;
-
-    // Maintain an old_index into the _old_methods array by skipping
-    // deleted methods
-    while ((old_array_method = (methodOop) _old_methods->obj_at(old_index))
-                                                            != old_method) {
-      ++old_index;
+#endif
+
+VM_RedefineClasses::FindAffectedKlassesClosure::FindAffectedKlassesClosure( GrowableArray<instanceKlassHandle> *original_klasses, GrowableArray<instanceKlassHandle> *result )
+{
+  assert(original_klasses != NULL && result != NULL, "");
+  this->_original_klasses = original_klasses;
+  this->_result = result;
+  SystemDictionary::classes_do(this);
+}
+
+void VM_RedefineClasses::FindAffectedKlassesClosure::do_object( oop obj )
+{
+  klassOop klass = (klassOop)obj;
+  assert(!_result->contains(klass), "must not occur more than once!");
+  assert(klass->klass_part()->new_version() == NULL, "Only last version is valid entry in system dictionary");
+
+  for(int i=0; i<_original_klasses->length(); i++) {
+    instanceKlassHandle cur = _original_klasses->at(i);
+    if (cur() != klass && klass->klass_part()->is_subtype_of(cur()) && !_original_klasses->contains(klass)) {  
+      RC_TRACE(0x00008000, ("Found affected class: %s", klass->klass_part()->name()->as_C_string()));
+      _result->append(klass);
+      break;
     }
-
-    if (MethodComparator::methods_EMCP(old_method, new_method)) {
-      // The EMCP definition from JSR-163 requires the bytecodes to be
-      // the same with the exception of constant pool indices which may
-      // differ. However, the constants referred to by those indices
-      // must be the same.
-      //
-      // We use methods_EMCP() for comparison since constant pool
-      // merging can remove duplicate constant pool entries that were
-      // present in the old method and removed from the rewritten new
-      // method. A faster binary comparison function would consider the
-      // old and new methods to be different when they are actually
-      // EMCP.
-      //
-      // The old and new methods are EMCP and you would think that we
-      // could get rid of one of them here and now and save some space.
-      // However, the concept of EMCP only considers the bytecodes and
-      // the constant pool entries in the comparison. Other things,
-      // e.g., the line number table (LNT) or the local variable table
-      // (LVT) don't count in the comparison. So the new (and EMCP)
-      // method can have a new LNT that we need so we can't just
-      // overwrite the new method with the old method.
-      //
-      // When this routine is called, we have already attached the new
-      // methods to the_class so the old methods are effectively
-      // overwritten. However, if an old method is still executing,
-      // then the old method cannot be collected until sometime after
-      // the old method call has returned. So the overwriting of old
-      // methods by new methods will save us space except for those
-      // (hopefully few) old methods that are still executing.
-      //
-      // A method refers to a constMethodOop and this presents another
-      // possible avenue to space savings. The constMethodOop in the
-      // new method contains possibly new attributes (LNT, LVT, etc).
-      // At first glance, it seems possible to save space by replacing
-      // the constMethodOop in the old method with the constMethodOop
-      // from the new method. The old and new methods would share the
-      // same constMethodOop and we would save the space occupied by
-      // the old constMethodOop. However, the constMethodOop contains
-      // a back reference to the containing method. Sharing the
-      // constMethodOop between two methods could lead to confusion in
-      // the code that uses the back reference. This would lead to
-      // brittle code that could be broken in non-obvious ways now or
-      // in the future.
-      //
-      // Another possibility is to copy the constMethodOop from the new
-      // method to the old method and then overwrite the new method with
-      // the old method. Since the constMethodOop contains the bytecodes
-      // for the method embedded in the oop, this option would change
-      // the bytecodes out from under any threads executing the old
-      // method and make the thread's bcp invalid. Since EMCP requires
-      // that the bytecodes be the same modulo constant pool indices, it
-      // is straight forward to compute the correct new bcp in the new
-      // constMethodOop from the old bcp in the old constMethodOop. The
-      // time consuming part would be searching all the frames in all
-      // of the threads to find all of the calls to the old method.
-      //
-      // It looks like we will have to live with the limited savings
-      // that we get from effectively overwriting the old methods
-      // when the new methods are attached to the_class.
-
-      // track which methods are EMCP for add_previous_version() call
-      emcp_methods->set_bit(old_index);
-      (*emcp_method_count_p)++;
-
-      // An EMCP method is _not_ obsolete. An obsolete method has a
-      // different jmethodID than the current method. An EMCP method
-      // has the same jmethodID as the current method. Having the
-      // same jmethodID for all EMCP versions of a method allows for
-      // a consistent view of the EMCP methods regardless of which
-      // EMCP method you happen to have in hand. For example, a
-      // breakpoint set in one EMCP method will work for all EMCP
-      // versions of the method including the current one.
-    } else {
-      // mark obsolete methods as such
-      old_method->set_is_obsolete();
-      obsolete_count++;
-
-      // obsolete methods need a unique idnum
-      u2 num = instanceKlass::cast(_the_class_oop)->next_method_idnum();
-      if (num != constMethodOopDesc::UNSET_IDNUM) {
-//      u2 old_num = old_method->method_idnum();
-        old_method->set_method_idnum(num);
-// TO DO: attach obsolete annotations to obsolete method's new idnum
+  }
+}
+
+jvmtiError VM_RedefineClasses::do_topological_class_sorting( const jvmtiClassDefinition *class_defs, int class_count, GrowableArray<instanceKlassHandle> *affected, GrowableArray<instanceKlassHandle> *arr, TRAPS)
+{
+  GrowableArray< Pair<klassOop, klassOop> > *links = new GrowableArray< Pair<klassOop, klassOop> >();
+
+  for (int i=0; i<class_count; i++) {
+
+    oop mirror = JNIHandles::resolve_non_null(class_defs[i].klass);
+    klassOop the_class_oop = java_lang_Class::as_klassOop(mirror);
+    instanceKlassHandle the_class(THREAD, the_class_oop);
+    Handle the_class_loader(THREAD, the_class->class_loader());
+    Handle protection_domain(THREAD, the_class->protection_domain());
+
+    ClassFileStream st((u1*) class_defs[i].class_bytes,
+      class_defs[i].class_byte_count, (char *)"__VM_RedefineClasses__");
+    ClassFileParser cfp(&st);
+
+    GrowableArray<Symbol*> symbolArr;
+    RC_TRACE(0x00000002, ("Before find super symbols of class %s",
+      the_class->name()->as_C_string()));
+    cfp.findSuperSymbols(the_class->name(), the_class_loader, protection_domain, the_class, symbolArr, THREAD);
+    
+    for (int j=0; j<symbolArr.length(); j++) {
+      Symbol* sym = symbolArr.at(j);
+
+      RC_TRACE(0x00008000, ("Before adding link to super class %s", sym->as_C_string()));
+
+      for (int k=0; k<arr->length(); k++) {
+        klassOop curOop = arr->at(k)();
+        // (tw) TODO: Check if we get aliasing problems with different class loaders?
+        if (curOop->klass_part()->name() == sym /*&& curOop->klass_part()->class_loader() == the_class_loader()*/) {
+          RC_TRACE(0x00000002, ("Found class to link"));
+          links->append(Pair<klassOop, klassOop>(curOop, the_class()));
+          break;
+        }
       }
-      // With tracing we try not to "yack" too much. The position of
-      // this trace assumes there are fewer obsolete methods than
-      // EMCP methods.
-      RC_TRACE(0x00000100, ("mark %s(%s) as obsolete",
-        old_method->name()->as_C_string(),
-        old_method->signature()->as_C_string()));
     }
-    old_method->set_is_old();
   }
-  for (int i = 0; i < _deleted_methods_length; ++i) {
-    methodOop old_method = _deleted_methods[i];
-
-    assert(old_method->vtable_index() < 0,
-           "cannot delete methods with vtable entries");;
-
-    // Mark all deleted methods as old and obsolete
-    old_method->set_is_old();
-    old_method->set_is_obsolete();
-    ++obsolete_count;
-    // With tracing we try not to "yack" too much. The position of
-    // this trace assumes there are fewer obsolete methods than
-    // EMCP methods.
-    RC_TRACE(0x00000100, ("mark deleted %s(%s) as obsolete",
-                          old_method->name()->as_C_string(),
-                          old_method->signature()->as_C_string()));
+
+
+  RC_TRACE(0x00000001, ("Identified links between classes! "));
+
+  for (int i=0; i<affected->length(); i++) {
+
+    instanceKlassHandle klass = affected->at(i);
+
+    klassOop superKlass = klass->super();
+    if (affected->contains(superKlass)) {
+      links->append(Pair<klassOop, klassOop>(superKlass, klass()));
+    }
+
+    objArrayOop superInterfaces = klass->local_interfaces();
+    for (int j=0; j<superInterfaces->length(); j++) {
+      klassOop interfaceKlass = (klassOop)superInterfaces->obj_at(j);
+      if (arr->contains(interfaceKlass)) {
+        links->append(Pair<klassOop, klassOop>(interfaceKlass, klass()));
+      }
+    }
   }
-  assert((*emcp_method_count_p + obsolete_count) == _old_methods->length(),
-    "sanity check");
-  RC_TRACE(0x00000100, ("EMCP_cnt=%d, obsolete_cnt=%d", *emcp_method_count_p,
-    obsolete_count));
+
+  if (RC_TRACE_ENABLED(0x00000002))  {
+    RC_TRACE(0x00000002, ("Identified links: "));
+    for (int i=0; i<links->length(); i++) {
+      RC_TRACE(0x00000002, ("%s to %s",
+        links->at(i).left()->klass_part()->name()->as_C_string(),
+        links->at(i).right()->klass_part()->name()->as_C_string()));
+    }
+  }
+
+  for (int i=0; i<arr->length(); i++) {
+
+    int j;
+    for (j=i; j<arr->length(); j++) {
+
+      int k;
+      for (k=0; k<links->length(); k++) {
+
+        klassOop k1 = links->adr_at(k)->right();
+        klassOop k2 = arr->at(j)();
+        if (k1 == k2) {
+          break;
+        }
+      }
+
+      if (k == links->length()) {
+        break;
+      }
+    }
+
+    if (j == arr->length()) {
+      // circle detected
+      return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
+    }
+
+    for (int k=0; k<links->length(); k++) {
+      if (links->adr_at(k)->left() == arr->at(j)()) {
+        links->at_put(k, links->at(links->length() - 1));
+        links->remove_at(links->length() - 1);
+        k--;
+      }
+    }
+
+    instanceKlassHandle tmp = arr->at(j);
+    arr->at_put(j, arr->at(i));
+    arr->at_put(i, tmp);
+  }
+
+  return JVMTI_ERROR_NONE;
 }
 
+void VM_RedefineClasses::oops_do(OopClosure *closure) {
+
+  if (_updated_oops != NULL) {
+    for (int i=0; i<_updated_oops->length(); i++) {
+      closure->do_oop(_updated_oops->adr_at(i));
+    }
+  }
+}
+
+void VM_RedefineClasses::transfer_special_access_flags(fieldDescriptor *from, fieldDescriptor *to) {
+  to->set_is_field_modification_watched(from->is_field_modification_watched());
+  to->set_is_field_access_watched(from->is_field_access_watched());
+  if (from->is_field_modification_watched() || from->is_field_access_watched()) {
+    RC_TRACE(0x00000002, ("Transfered watch for field %s",
+      from->name()->as_C_string()));
+  }
+  update_klass_field_access_flag(to);
+}
+
+void VM_RedefineClasses::update_klass_field_access_flag(fieldDescriptor *fd) {
+  instanceKlass* ik = instanceKlass::cast(fd->field_holder());
+  FieldInfo* fi = FieldInfo::from_field_array(ik->fields(), fd->index());
+  fi->set_access_flags(fd->access_flags().as_short());
+}
+
+
 // This internal class transfers the native function registration from old methods
 // to new methods.  It is designed to handle both the simple case of unchanged
 // native methods and the complex cases of native method prefixes being added and/or
@@ -2842,7 +3167,7 @@
 // Same, caused by prefix removal only  3_2_1_m ->  3_2_m
 //
 class TransferNativeFunctionRegistration {
- private:
+private:
   instanceKlassHandle the_class;
   int prefix_count;
   char** prefixes;
@@ -2855,42 +3180,42 @@
   //    (2) with the prefix.
   // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
   methodOop search_prefix_name_space(int depth, char* name_str, size_t name_len,
-                                     Symbol* signature) {
-    TempNewSymbol name_symbol = SymbolTable::probe(name_str, (int)name_len);
-    if (name_symbol != NULL) {
-      methodOop method = Klass::cast(the_class())->lookup_method(name_symbol, signature);
-      if (method != NULL) {
-        // Even if prefixed, intermediate methods must exist.
-        if (method->is_native()) {
-          // Wahoo, we found a (possibly prefixed) version of the method, return it.
-          return method;
-        }
-        if (depth < prefix_count) {
-          // Try applying further prefixes (other than this one).
-          method = search_prefix_name_space(depth+1, name_str, name_len, signature);
-          if (method != NULL) {
-            return method; // found
+    Symbol* signature) {
+      Symbol* name_symbol = SymbolTable::probe(name_str, (int)name_len);
+      if (name_symbol != NULL) {
+        methodOop method = Klass::cast(the_class()->klass_part()->new_version())->lookup_method(name_symbol, signature);
+        if (method != NULL) {
+          // Even if prefixed, intermediate methods must exist.
+          if (method->is_native()) {
+            // Wahoo, we found a (possibly prefixed) version of the method, return it.
+            return method;
           }
-
-          // Try adding this prefix to the method name and see if it matches
-          // another method name.
-          char* prefix = prefixes[depth];
-          size_t prefix_len = strlen(prefix);
-          size_t trial_len = name_len + prefix_len;
-          char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
-          strcpy(trial_name_str, prefix);
-          strcat(trial_name_str, name_str);
-          method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
-                                            signature);
-          if (method != NULL) {
-            // If found along this branch, it was prefixed, mark as such
-            method->set_is_prefixed_native();
-            return method; // found
+          if (depth < prefix_count) {
+            // Try applying further prefixes (other than this one).
+            method = search_prefix_name_space(depth+1, name_str, name_len, signature);
+            if (method != NULL) {
+              return method; // found
+            }
+
+            // Try adding this prefix to the method name and see if it matches
+            // another method name.
+            char* prefix = prefixes[depth];
+            size_t prefix_len = strlen(prefix);
+            size_t trial_len = name_len + prefix_len;
+            char* trial_name_str = NEW_RESOURCE_ARRAY(char, trial_len + 1);
+            strcpy(trial_name_str, prefix);
+            strcat(trial_name_str, name_str);
+            method = search_prefix_name_space(depth+1, trial_name_str, trial_len,
+              signature);
+            if (method != NULL) {
+              // If found along this branch, it was prefixed, mark as such
+              method->set_is_prefixed_native();
+              return method; // found
+            }
           }
         }
       }
-    }
-    return NULL;  // This whole branch bore nothing
+      return NULL;  // This whole branch bore nothing
   }
 
   // Return the method name with old prefixes stripped away.
@@ -2915,10 +3240,10 @@
     ResourceMark rm;
     char* name_str = method_name_without_prefixes(method);
     return search_prefix_name_space(0, name_str, strlen(name_str),
-                                    method->signature());
+      method->signature());
   }
 
- public:
+public:
 
   // Construct a native method transfer processor for this class.
   TransferNativeFunctionRegistration(instanceKlassHandle _the_class) {
@@ -2929,9 +3254,9 @@
   }
 
   // Attempt to transfer any of the old or deleted methods that are native
-  void transfer_registrations(methodOop* old_methods, int methods_length) {
+  void transfer_registrations(instanceKlassHandle old_klass, int* old_methods, int methods_length) {
     for (int j = 0; j < methods_length; j++) {
-      methodOop old_method = old_methods[j];
+      methodOop old_method = (methodOop)old_klass->methods()->obj_at(old_methods[j]);
 
       if (old_method->is_native() && old_method->has_native_function()) {
         methodOop new_method = strip_and_search_for_new_native(old_method);
@@ -2940,7 +3265,9 @@
           // Redefine does not send events (except CFLH), certainly not this
           // behind the scenes re-registration.
           new_method->set_native_function(old_method->native_function(),
-                              !methodOopDesc::native_bind_event_is_interesting);
+            !methodOopDesc::native_bind_event_is_interesting);
+
+          RC_TRACE(0x00008000, ("Transfering native function for method %s", old_method->name()->as_C_string()));
         }
       }
     }
@@ -2948,494 +3275,8 @@
 };
 
 // Don't lose the association between a native method and its JNI function.
-void VM_RedefineClasses::transfer_old_native_function_registrations(instanceKlassHandle the_class) {
-  TransferNativeFunctionRegistration transfer(the_class);
-  transfer.transfer_registrations(_deleted_methods, _deleted_methods_length);
-  transfer.transfer_registrations(_matching_old_methods, _matching_methods_length);
+void VM_RedefineClasses::transfer_old_native_function_registrations(instanceKlassHandle old_klass) {
+  TransferNativeFunctionRegistration transfer(old_klass);
+  transfer.transfer_registrations(old_klass, _deleted_methods, _deleted_methods_length);
+  transfer.transfer_registrations(old_klass, _matching_old_methods, _matching_methods_length);
 }
-
-// Deoptimize all compiled code that depends on this class.
-//
-// If the can_redefine_classes capability is obtained in the onload
-// phase then the compiler has recorded all dependencies from startup.
-// In that case we need only deoptimize and throw away all compiled code
-// that depends on the class.
-//
-// If can_redefine_classes is obtained sometime after the onload
-// phase then the dependency information may be incomplete. In that case
-// the first call to RedefineClasses causes all compiled code to be
-// thrown away. As can_redefine_classes has been obtained then
-// all future compilations will record dependencies so second and
-// subsequent calls to RedefineClasses need only throw away code
-// that depends on the class.
-//
-void VM_RedefineClasses::flush_dependent_code(instanceKlassHandle k_h, TRAPS) {
-  assert_locked_or_safepoint(Compile_lock);
-
-  // All dependencies have been recorded from startup or this is a second or
-  // subsequent use of RedefineClasses
-  if (JvmtiExport::all_dependencies_are_recorded()) {
-    Universe::flush_evol_dependents_on(k_h);
-  } else {
-    CodeCache::mark_all_nmethods_for_deoptimization();
-
-    ResourceMark rm(THREAD);
-    DeoptimizationMarker dm;
-
-    // Deoptimize all activations depending on marked nmethods
-    Deoptimization::deoptimize_dependents();
-
-    // Make the dependent methods not entrant (in VM_Deoptimize they are made zombies)
-    CodeCache::make_marked_nmethods_not_entrant();
-
-    // From now on we know that the dependency information is complete
-    JvmtiExport::set_all_dependencies_are_recorded(true);
-  }
-}
-
-void VM_RedefineClasses::compute_added_deleted_matching_methods() {
-  methodOop old_method;
-  methodOop new_method;
-
-  _matching_old_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length());
-  _matching_new_methods = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length());
-  _added_methods        = NEW_RESOURCE_ARRAY(methodOop, _new_methods->length());
-  _deleted_methods      = NEW_RESOURCE_ARRAY(methodOop, _old_methods->length());
-
-  _matching_methods_length = 0;
-  _deleted_methods_length  = 0;
-  _added_methods_length    = 0;
-
-  int nj = 0;
-  int oj = 0;
-  while (true) {
-    if (oj >= _old_methods->length()) {
-      if (nj >= _new_methods->length()) {
-        break; // we've looked at everything, done
-      }
-      // New method at the end
-      new_method = (methodOop) _new_methods->obj_at(nj);
-      _added_methods[_added_methods_length++] = new_method;
-      ++nj;
-    } else if (nj >= _new_methods->length()) {
-      // Old method, at the end, is deleted
-      old_method = (methodOop) _old_methods->obj_at(oj);
-      _deleted_methods[_deleted_methods_length++] = old_method;
-      ++oj;
-    } else {
-      old_method = (methodOop) _old_methods->obj_at(oj);
-      new_method = (methodOop) _new_methods->obj_at(nj);
-      if (old_method->name() == new_method->name()) {
-        if (old_method->signature() == new_method->signature()) {
-          _matching_old_methods[_matching_methods_length  ] = old_method;
-          _matching_new_methods[_matching_methods_length++] = new_method;
-          ++nj;
-          ++oj;
-        } else {
-          // added overloaded have already been moved to the end,
-          // so this is a deleted overloaded method
-          _deleted_methods[_deleted_methods_length++] = old_method;
-          ++oj;
-        }
-      } else { // names don't match
-        if (old_method->name()->fast_compare(new_method->name()) > 0) {
-          // new method
-          _added_methods[_added_methods_length++] = new_method;
-          ++nj;
-        } else {
-          // deleted method
-          _deleted_methods[_deleted_methods_length++] = old_method;
-          ++oj;
-        }
-      }
-    }
-  }
-  assert(_matching_methods_length + _deleted_methods_length == _old_methods->length(), "sanity");
-  assert(_matching_methods_length + _added_methods_length == _new_methods->length(), "sanity");
-}
-
-
-
-// Install the redefinition of a class:
-//    - house keeping (flushing breakpoints and caches, deoptimizing
-//      dependent compiled code)
-//    - replacing parts in the_class with parts from scratch_class
-//    - adding a weak reference to track the obsolete but interesting
-//      parts of the_class
-//    - adjusting constant pool caches and vtables in other classes
-//      that refer to methods in the_class. These adjustments use the
-//      SystemDictionary::classes_do() facility which only allows
-//      a helper method to be specified. The interesting parameters
-//      that we would like to pass to the helper method are saved in
-//      static global fields in the VM operation.
-void VM_RedefineClasses::redefine_single_class(jclass the_jclass,
-       instanceKlassHandle scratch_class, TRAPS) {
-
-  RC_TIMER_START(_timer_rsc_phase1);
-
-  oop the_class_mirror = JNIHandles::resolve_non_null(the_jclass);
-  klassOop the_class_oop = java_lang_Class::as_klassOop(the_class_mirror);
-  instanceKlassHandle the_class = instanceKlassHandle(THREAD, the_class_oop);
-
-#ifndef JVMTI_KERNEL
-  // Remove all breakpoints in methods of this class
-  JvmtiBreakpoints& jvmti_breakpoints = JvmtiCurrentBreakpoints::get_jvmti_breakpoints();
-  jvmti_breakpoints.clearall_in_class_at_safepoint(the_class_oop);
-#endif // !JVMTI_KERNEL
-
-  if (the_class_oop == Universe::reflect_invoke_cache()->klass()) {
-    // We are redefining java.lang.reflect.Method. Method.invoke() is
-    // cached and users of the cache care about each active version of
-    // the method so we have to track this previous version.
-    // Do this before methods get switched
-    Universe::reflect_invoke_cache()->add_previous_version(
-      the_class->method_with_idnum(Universe::reflect_invoke_cache()->method_idnum()));
-  }
-
-  // Deoptimize all compiled code that depends on this class
-  flush_dependent_code(the_class, THREAD);
-
-  _old_methods = the_class->methods();
-  _new_methods = scratch_class->methods();
-  _the_class_oop = the_class_oop;
-  compute_added_deleted_matching_methods();
-  update_jmethod_ids();
-
-  // Attach new constant pool to the original klass. The original
-  // klass still refers to the old constant pool (for now).
-  scratch_class->constants()->set_pool_holder(the_class());
-
-#if 0
-  // In theory, with constant pool merging in place we should be able
-  // to save space by using the new, merged constant pool in place of
-  // the old constant pool(s). By "pool(s)" I mean the constant pool in
-  // the klass version we are replacing now and any constant pool(s) in
-  // previous versions of klass. Nice theory, doesn't work in practice.
-  // When this code is enabled, even simple programs throw NullPointer
-  // exceptions. I'm guessing that this is caused by some constant pool
-  // cache difference between the new, merged constant pool and the
-  // constant pool that was just being used by the klass. I'm keeping
-  // this code around to archive the idea, but the code has to remain
-  // disabled for now.
-
-  // Attach each old method to the new constant pool. This can be
-  // done here since we are past the bytecode verification and
-  // constant pool optimization phases.
-  for (int i = _old_methods->length() - 1; i >= 0; i--) {
-    methodOop method = (methodOop)_old_methods->obj_at(i);
-    method->set_constants(scratch_class->constants());
-  }
-
-  {
-    // walk all previous versions of the klass
-    instanceKlass *ik = (instanceKlass *)the_class()->klass_part();
-    PreviousVersionWalker pvw(ik);
-    instanceKlassHandle ikh;
-    do {
-      ikh = pvw.next_previous_version();
-      if (!ikh.is_null()) {
-        ik = ikh();
-
-        // attach previous version of klass to the new constant pool
-        ik->set_constants(scratch_class->constants());
-
-        // Attach each method in the previous version of klass to the
-        // new constant pool
-        objArrayOop prev_methods = ik->methods();
-        for (int i = prev_methods->length() - 1; i >= 0; i--) {
-          methodOop method = (methodOop)prev_methods->obj_at(i);
-          method->set_constants(scratch_class->constants());
-        }
-      }
-    } while (!ikh.is_null());
-  }
-#endif
-
-  // Replace methods and constantpool
-  the_class->set_methods(_new_methods);
-  scratch_class->set_methods(_old_methods);     // To prevent potential GCing of the old methods,
-                                          // and to be able to undo operation easily.
-
-  constantPoolOop old_constants = the_class->constants();
-  the_class->set_constants(scratch_class->constants());
-  scratch_class->set_constants(old_constants);  // See the previous comment.
-#if 0
-  // We are swapping the guts of "the new class" with the guts of "the
-  // class". Since the old constant pool has just been attached to "the
-  // new class", it seems logical to set the pool holder in the old
-  // constant pool also. However, doing this will change the observable
-  // class hierarchy for any old methods that are still executing. A
-  // method can query the identity of its "holder" and this query uses
-  // the method's constant pool link to find the holder. The change in
-  // holding class from "the class" to "the new class" can confuse
-  // things.
-  //
-  // Setting the old constant pool's holder will also cause
-  // verification done during vtable initialization below to fail.
-  // During vtable initialization, the vtable's class is verified to be
-  // a subtype of the method's holder. The vtable's class is "the
-  // class" and the method's holder is gotten from the constant pool
-  // link in the method itself. For "the class"'s directly implemented
-  // methods, the method holder is "the class" itself (as gotten from
-  // the new constant pool). The check works fine in this case. The
-  // check also works fine for methods inherited from super classes.
-  //
-  // Miranda methods are a little more complicated. A miranda method is
-  // provided by an interface when the class implementing the interface
-  // does not provide its own method.  These interfaces are implemented
-  // internally as an instanceKlass. These special instanceKlasses
-  // share the constant pool of the class that "implements" the
-  // interface. By sharing the constant pool, the method holder of a
-  // miranda method is the class that "implements" the interface. In a
-  // non-redefine situation, the subtype check works fine. However, if
-  // the old constant pool's pool holder is modified, then the check
-  // fails because there is no class hierarchy relationship between the
-  // vtable's class and "the new class".
-
-  old_constants->set_pool_holder(scratch_class());
-#endif
-
-  // track which methods are EMCP for add_previous_version() call below
-  BitMap emcp_methods(_old_methods->length());
-  int emcp_method_count = 0;
-  emcp_methods.clear();  // clears 0..(length() - 1)
-  check_methods_and_mark_as_obsolete(&emcp_methods, &emcp_method_count);
-  transfer_old_native_function_registrations(the_class);
-
-  // The class file bytes from before any retransformable agents mucked
-  // with them was cached on the scratch class, move to the_class.
-  // Note: we still want to do this if nothing needed caching since it
-  // should get cleared in the_class too.
-  if (the_class->get_cached_class_file_bytes() == 0) {
-    // the_class doesn't have a cache yet so copy it
-    the_class->set_cached_class_file(
-      scratch_class->get_cached_class_file_bytes(),
-      scratch_class->get_cached_class_file_len());
-  }
-#ifndef PRODUCT
-  else {
-    assert(the_class->get_cached_class_file_bytes() ==
-      scratch_class->get_cached_class_file_bytes(), "cache ptrs must match");
-    assert(the_class->get_cached_class_file_len() ==
-      scratch_class->get_cached_class_file_len(), "cache lens must match");
-  }
-#endif
-
-  // Replace inner_classes
-  typeArrayOop old_inner_classes = the_class->inner_classes();
-  the_class->set_inner_classes(scratch_class->inner_classes());
-  scratch_class->set_inner_classes(old_inner_classes);
-
-  // Initialize the vtable and interface table after
-  // methods have been rewritten
-  {
-    ResourceMark rm(THREAD);
-    // no exception should happen here since we explicitly
-    // do not check loader constraints.
-    // compare_and_normalize_class_versions has already checked:
-    //  - classloaders unchanged, signatures unchanged
-    //  - all instanceKlasses for redefined classes reused & contents updated
-    the_class->vtable()->initialize_vtable(false, THREAD);
-    the_class->itable()->initialize_itable(false, THREAD);
-    assert(!HAS_PENDING_EXCEPTION || (THREAD->pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())), "redefine exception");
-  }
-
-  // Leave arrays of jmethodIDs and itable index cache unchanged
-
-  // Copy the "source file name" attribute from new class version
-  the_class->set_source_file_name(scratch_class->source_file_name());
-
-  // Copy the "source debug extension" attribute from new class version
-  the_class->set_source_debug_extension(
-    scratch_class->source_debug_extension());
-
-  // Use of javac -g could be different in the old and the new
-  if (scratch_class->access_flags().has_localvariable_table() !=
-      the_class->access_flags().has_localvariable_table()) {
-
-    AccessFlags flags = the_class->access_flags();
-    if (scratch_class->access_flags().has_localvariable_table()) {
-      flags.set_has_localvariable_table();
-    } else {
-      flags.clear_has_localvariable_table();
-    }
-    the_class->set_access_flags(flags);
-  }
-
-  // Replace class annotation fields values
-  typeArrayOop old_class_annotations = the_class->class_annotations();
-  the_class->set_class_annotations(scratch_class->class_annotations());
-  scratch_class->set_class_annotations(old_class_annotations);
-
-  // Replace fields annotation fields values
-  objArrayOop old_fields_annotations = the_class->fields_annotations();
-  the_class->set_fields_annotations(scratch_class->fields_annotations());
-  scratch_class->set_fields_annotations(old_fields_annotations);
-
-  // Replace methods annotation fields values
-  objArrayOop old_methods_annotations = the_class->methods_annotations();
-  the_class->set_methods_annotations(scratch_class->methods_annotations());
-  scratch_class->set_methods_annotations(old_methods_annotations);
-
-  // Replace methods parameter annotation fields values
-  objArrayOop old_methods_parameter_annotations =
-    the_class->methods_parameter_annotations();
-  the_class->set_methods_parameter_annotations(
-    scratch_class->methods_parameter_annotations());
-  scratch_class->set_methods_parameter_annotations(old_methods_parameter_annotations);
-
-  // Replace methods default annotation fields values
-  objArrayOop old_methods_default_annotations =
-    the_class->methods_default_annotations();
-  the_class->set_methods_default_annotations(
-    scratch_class->methods_default_annotations());
-  scratch_class->set_methods_default_annotations(old_methods_default_annotations);
-
-  // Replace minor version number of class file
-  u2 old_minor_version = the_class->minor_version();
-  the_class->set_minor_version(scratch_class->minor_version());
-  scratch_class->set_minor_version(old_minor_version);
-
-  // Replace major version number of class file
-  u2 old_major_version = the_class->major_version();
-  the_class->set_major_version(scratch_class->major_version());
-  scratch_class->set_major_version(old_major_version);
-
-  // Replace CP indexes for class and name+type of enclosing method
-  u2 old_class_idx  = the_class->enclosing_method_class_index();
-  u2 old_method_idx = the_class->enclosing_method_method_index();
-  the_class->set_enclosing_method_indices(
-    scratch_class->enclosing_method_class_index(),
-    scratch_class->enclosing_method_method_index());
-  scratch_class->set_enclosing_method_indices(old_class_idx, old_method_idx);
-
-  // keep track of previous versions of this class
-  the_class->add_previous_version(scratch_class, &emcp_methods,
-    emcp_method_count);
-
-  RC_TIMER_STOP(_timer_rsc_phase1);
-  RC_TIMER_START(_timer_rsc_phase2);
-
-  // Adjust constantpool caches and vtables for all classes
-  // that reference methods of the evolved class.
-  SystemDictionary::classes_do(adjust_cpool_cache_and_vtable, THREAD);
-
-  if (the_class->oop_map_cache() != NULL) {
-    // Flush references to any obsolete methods from the oop map cache
-    // so that obsolete methods are not pinned.
-    the_class->oop_map_cache()->flush_obsolete_entries();
-  }
-
-  // increment the classRedefinedCount field in the_class and in any
-  // direct and indirect subclasses of the_class
-  increment_class_counter((instanceKlass *)the_class()->klass_part(), THREAD);
-
-  // RC_TRACE macro has an embedded ResourceMark
-  RC_TRACE_WITH_THREAD(0x00000001, THREAD,
-    ("redefined name=%s, count=%d (avail_mem=" UINT64_FORMAT "K)",
-    the_class->external_name(),
-    java_lang_Class::classRedefinedCount(the_class_mirror),
-    os::available_memory() >> 10));
-
-  RC_TIMER_STOP(_timer_rsc_phase2);
-} // end redefine_single_class()
-
-
-// Increment the classRedefinedCount field in the specific instanceKlass
-// and in all direct and indirect subclasses.
-void VM_RedefineClasses::increment_class_counter(instanceKlass *ik, TRAPS) {
-  oop class_mirror = ik->java_mirror();
-  klassOop class_oop = java_lang_Class::as_klassOop(class_mirror);
-  int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
-  java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
-
-  if (class_oop != _the_class_oop) {
-    // _the_class_oop count is printed at end of redefine_single_class()
-    RC_TRACE_WITH_THREAD(0x00000008, THREAD,
-      ("updated count in subclass=%s to %d", ik->external_name(), new_count));
-  }
-
-  for (Klass *subk = ik->subklass(); subk != NULL;
-       subk = subk->next_sibling()) {
-    if (subk->oop_is_instance()) {
-      // Only update instanceKlasses
-      instanceKlass *subik = (instanceKlass*)subk;
-      // recursively do subclasses of the current subclass
-      increment_class_counter(subik, THREAD);
-    }
-  }
-}
-
-#ifndef PRODUCT
-void VM_RedefineClasses::check_class(klassOop k_oop,
-       oop initiating_loader, TRAPS) {
-  Klass *k = k_oop->klass_part();
-  if (k->oop_is_instance()) {
-    HandleMark hm(THREAD);
-    instanceKlass *ik = (instanceKlass *) k;
-
-    if (ik->vtable_length() > 0) {
-      ResourceMark rm(THREAD);
-      if (!ik->vtable()->check_no_old_entries()) {
-        tty->print_cr("klassVtable::check_no_old_entries failure -- OLD method found -- class: %s", ik->signature_name());
-        ik->vtable()->dump_vtable();
-        dump_methods();
-        assert(false, "OLD method found");
-      }
-    }
-  }
-}
-
-void VM_RedefineClasses::dump_methods() {
-        int j;
-        tty->print_cr("_old_methods --");
-        for (j = 0; j < _old_methods->length(); ++j) {
-          methodOop m = (methodOop) _old_methods->obj_at(j);
-          tty->print("%4d  (%5d)  ", j, m->vtable_index());
-          m->access_flags().print_on(tty);
-          tty->print(" --  ");
-          m->print_name(tty);
-          tty->cr();
-        }
-        tty->print_cr("_new_methods --");
-        for (j = 0; j < _new_methods->length(); ++j) {
-          methodOop m = (methodOop) _new_methods->obj_at(j);
-          tty->print("%4d  (%5d)  ", j, m->vtable_index());
-          m->access_flags().print_on(tty);
-          tty->print(" --  ");
-          m->print_name(tty);
-          tty->cr();
-        }
-        tty->print_cr("_matching_(old/new)_methods --");
-        for (j = 0; j < _matching_methods_length; ++j) {
-          methodOop m = _matching_old_methods[j];
-          tty->print("%4d  (%5d)  ", j, m->vtable_index());
-          m->access_flags().print_on(tty);
-          tty->print(" --  ");
-          m->print_name(tty);
-          tty->cr();
-          m = _matching_new_methods[j];
-          tty->print("      (%5d)  ", m->vtable_index());
-          m->access_flags().print_on(tty);
-          tty->cr();
-        }
-        tty->print_cr("_deleted_methods --");
-        for (j = 0; j < _deleted_methods_length; ++j) {
-          methodOop m = _deleted_methods[j];
-          tty->print("%4d  (%5d)  ", j, m->vtable_index());
-          m->access_flags().print_on(tty);
-          tty->print(" --  ");
-          m->print_name(tty);
-          tty->cr();
-        }
-        tty->print_cr("_added_methods --");
-        for (j = 0; j < _added_methods_length; ++j) {
-          methodOop m = _added_methods[j];
-          tty->print("%4d  (%5d)  ", j, m->vtable_index());
-          m->access_flags().print_on(tty);
-          tty->print(" --  ");
-          m->print_name(tty);
-          tty->cr();
-        }
-}
-#endif
diff --git a/src/share/vm/prims/jvmtiRedefineClasses.hpp b/src/share/vm/prims/jvmtiRedefineClasses.hpp
--- a/src/share/vm/prims/jvmtiRedefineClasses.hpp
+++ b/src/share/vm/prims/jvmtiRedefineClasses.hpp
@@ -1,26 +1,29 @@
 /*
- * Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This code is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- *
- */
+* Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
+* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+*
+* This code is free software; you can redistribute it and/or modify it
+* under the terms of the GNU General Public License version 2 only, as
+* published by the Free Software Foundation.
+*
+* This code is distributed in the hope that it will be useful, but WITHOUT
+* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+* FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+* version 2 for more details (a copy is included in the LICENSE file that
+* accompanied this code).
+*
+* You should have received a copy of the GNU General Public License version
+* 2 along with this work; if not, write to the Free Software Foundation,
+* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+*
+* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+* or visit www.oracle.com if you need additional information or have any
+* questions.
+*
+*/
+
+// New version that allows arbitrary changes to already loaded classes.
+// Modifications done by: Thomas Wuerthinger <thomas.wuerthinger@gmail.com>
 
 #ifndef SHARE_VM_PRIMS_JVMTIREDEFINECLASSES_HPP
 #define SHARE_VM_PRIMS_JVMTIREDEFINECLASSES_HPP
@@ -32,331 +35,28 @@
 #include "oops/objArrayOop.hpp"
 #include "prims/jvmtiRedefineClassesTrace.hpp"
 #include "runtime/vm_operations.hpp"
+#include "gc_implementation/shared/vmGCOperations.hpp"
 
-// Introduction:
-//
-// The RedefineClasses() API is used to change the definition of one or
-// more classes. While the API supports redefining more than one class
-// in a single call, in general, the API is discussed in the context of
-// changing the definition of a single current class to a single new
-// class. For clarity, the current class is will always be called
-// "the_class" and the new class will always be called "scratch_class".
-//
-// The name "the_class" is used because there is only one structure
-// that represents a specific class; redefinition does not replace the
-// structure, but instead replaces parts of the structure. The name
-// "scratch_class" is used because the structure that represents the
-// new definition of a specific class is simply used to carry around
-// the parts of the new definition until they are used to replace the
-// appropriate parts in the_class. Once redefinition of a class is
-// complete, scratch_class is thrown away.
-//
-//
-// Implementation Overview:
-//
-// The RedefineClasses() API is mostly a wrapper around the VM op that
-// does the real work. The work is split in varying degrees between
-// doit_prologue(), doit() and doit_epilogue().
-//
-// 1) doit_prologue() is called by the JavaThread on the way to a
-//    safepoint. It does parameter verification and loads scratch_class
-//    which involves:
-//    - parsing the incoming class definition using the_class' class
-//      loader and security context
-//    - linking scratch_class
-//    - merging constant pools and rewriting bytecodes as needed
-//      for the merged constant pool
-//    - verifying the bytecodes in scratch_class
-//    - setting up the constant pool cache and rewriting bytecodes
-//      as needed to use the cache
-//    - finally, scratch_class is compared to the_class to verify
-//      that it is a valid replacement class
-//    - if everything is good, then scratch_class is saved in an
-//      instance field in the VM operation for the doit() call
-//
-//    Note: A JavaThread must do the above work.
-//
-// 2) doit() is called by the VMThread during a safepoint. It installs
-//    the new class definition(s) which involves:
-//    - retrieving the scratch_class from the instance field in the
-//      VM operation
-//    - house keeping (flushing breakpoints and caches, deoptimizing
-//      dependent compiled code)
-//    - replacing parts in the_class with parts from scratch_class
-//    - adding weak reference(s) to track the obsolete but interesting
-//      parts of the_class
-//    - adjusting constant pool caches and vtables in other classes
-//      that refer to methods in the_class. These adjustments use the
-//      SystemDictionary::classes_do() facility which only allows
-//      a helper method to be specified. The interesting parameters
-//      that we would like to pass to the helper method are saved in
-//      static global fields in the VM operation.
-//    - telling the SystemDictionary to notice our changes
-//
-//    Note: the above work must be done by the VMThread to be safe.
-//
-// 3) doit_epilogue() is called by the JavaThread after the VM op
-//    is finished and the safepoint is done. It simply cleans up
-//    memory allocated in doit_prologue() and used in doit().
-//
-//
-// Constant Pool Details:
-//
-// When the_class is redefined, we cannot just replace the constant
-// pool in the_class with the constant pool from scratch_class because
-// that could confuse obsolete methods that may still be running.
-// Instead, the constant pool from the_class, old_cp, is merged with
-// the constant pool from scratch_class, scratch_cp. The resulting
-// constant pool, merge_cp, replaces old_cp in the_class.
-//
-// The key part of any merging algorithm is the entry comparison
-// function so we have to know the types of entries in a constant pool
-// in order to merge two of them together. Constant pools can contain
-// up to 12 different kinds of entries; the JVM_CONSTANT_Unicode entry
-// is not presently used so we only have to worry about the other 11
-// entry types. For the purposes of constant pool merging, it is
-// helpful to know that the 11 entry types fall into 3 different
-// subtypes: "direct", "indirect" and "double-indirect".
-//
-// Direct CP entries contain data and do not contain references to
-// other CP entries. The following are direct CP entries:
-//     JVM_CONSTANT_{Double,Float,Integer,Long,Utf8}
-//
-// Indirect CP entries contain 1 or 2 references to a direct CP entry
-// and no other data. The following are indirect CP entries:
-//     JVM_CONSTANT_{Class,NameAndType,String}
-//
-// Double-indirect CP entries contain two references to indirect CP
-// entries and no other data. The following are double-indirect CP
-// entries:
-//     JVM_CONSTANT_{Fieldref,InterfaceMethodref,Methodref}
-//
-// When comparing entries between two constant pools, the entry types
-// are compared first and if they match, then further comparisons are
-// made depending on the entry subtype. Comparing direct CP entries is
-// simply a matter of comparing the data associated with each entry.
-// Comparing both indirect and double-indirect CP entries requires
-// recursion.
-//
-// Fortunately, the recursive combinations are limited because indirect
-// CP entries can only refer to direct CP entries and double-indirect
-// CP entries can only refer to indirect CP entries. The following is
-// an example illustration of the deepest set of indirections needed to
-// access the data associated with a JVM_CONSTANT_Fieldref entry:
-//
-//     JVM_CONSTANT_Fieldref {
-//         class_index => JVM_CONSTANT_Class {
-//             name_index => JVM_CONSTANT_Utf8 {
-//                 <data-1>
-//             }
-//         }
-//         name_and_type_index => JVM_CONSTANT_NameAndType {
-//             name_index => JVM_CONSTANT_Utf8 {
-//                 <data-2>
-//             }
-//             descriptor_index => JVM_CONSTANT_Utf8 {
-//                 <data-3>
-//             }
-//         }
-//     }
-//
-// The above illustration is not a data structure definition for any
-// computer language. The curly braces ('{' and '}') are meant to
-// delimit the context of the "fields" in the CP entry types shown.
-// Each indirection from the JVM_CONSTANT_Fieldref entry is shown via
-// "=>", e.g., the class_index is used to indirectly reference a
-// JVM_CONSTANT_Class entry where the name_index is used to indirectly
-// reference a JVM_CONSTANT_Utf8 entry which contains the interesting
-// <data-1>. In order to understand a JVM_CONSTANT_Fieldref entry, we
-// have to do a total of 5 indirections just to get to the CP entries
-// that contain the interesting pieces of data and then we have to
-// fetch the three pieces of data. This means we have to do a total of
-// (5 + 3) * 2 == 16 dereferences to compare two JVM_CONSTANT_Fieldref
-// entries.
-//
-// Here is the indirection, data and dereference count for each entry
-// type:
-//
-//    JVM_CONSTANT_Class               1 indir, 1 data, 2 derefs
-//    JVM_CONSTANT_Double              0 indir, 1 data, 1 deref
-//    JVM_CONSTANT_Fieldref            2 indir, 3 data, 8 derefs
-//    JVM_CONSTANT_Float               0 indir, 1 data, 1 deref
-//    JVM_CONSTANT_Integer             0 indir, 1 data, 1 deref
-//    JVM_CONSTANT_InterfaceMethodref  2 indir, 3 data, 8 derefs
-//    JVM_CONSTANT_Long                0 indir, 1 data, 1 deref
-//    JVM_CONSTANT_Methodref           2 indir, 3 data, 8 derefs
-//    JVM_CONSTANT_NameAndType         1 indir, 2 data, 4 derefs
-//    JVM_CONSTANT_String              1 indir, 1 data, 2 derefs
-//    JVM_CONSTANT_Utf8                0 indir, 1 data, 1 deref
-//
-// So different subtypes of CP entries require different amounts of
-// work for a proper comparison.
-//
-// Now that we've talked about the different entry types and how to
-// compare them we need to get back to merging. This is not a merge in
-// the "sort -u" sense or even in the "sort" sense. When we merge two
-// constant pools, we copy all the entries from old_cp to merge_cp,
-// preserving entry order. Next we append all the unique entries from
-// scratch_cp to merge_cp and we track the index changes from the
-// location in scratch_cp to the possibly new location in merge_cp.
-// When we are done, any obsolete code that is still running that
-// uses old_cp should not be able to observe any difference if it
-// were to use merge_cp. As for the new code in scratch_class, it is
-// modified to use the appropriate index values in merge_cp before it
-// is used to replace the code in the_class.
-//
-// There is one small complication in copying the entries from old_cp
-// to merge_cp. Two of the CP entry types are special in that they are
-// lazily resolved. Before explaining the copying complication, we need
-// to digress into CP entry resolution.
-//
-// JVM_CONSTANT_Class and JVM_CONSTANT_String entries are present in
-// the class file, but are not stored in memory as such until they are
-// resolved. The entries are not resolved unless they are used because
-// resolution is expensive. During class file parsing the entries are
-// initially stored in memory as JVM_CONSTANT_ClassIndex and
-// JVM_CONSTANT_StringIndex entries. These special CP entry types
-// indicate that the JVM_CONSTANT_Class and JVM_CONSTANT_String entries
-// have been parsed, but the index values in the entries have not been
-// validated. After the entire constant pool has been parsed, the index
-// values can be validated and then the entries are converted into
-// JVM_CONSTANT_UnresolvedClass and JVM_CONSTANT_UnresolvedString
-// entries. During this conversion process, the UTF8 values that are
-// indirectly referenced by the JVM_CONSTANT_ClassIndex and
-// JVM_CONSTANT_StringIndex entries are changed into Symbol*s and the
-// entries are modified to refer to the Symbol*s. This optimization
-// eliminates one level of indirection for those two CP entry types and
-// gets the entries ready for verification. During class file parsing
-// it is also possible for JVM_CONSTANT_UnresolvedString entries to be
-// resolved into JVM_CONSTANT_String entries. Verification expects to
-// find JVM_CONSTANT_UnresolvedClass and either JVM_CONSTANT_String or
-// JVM_CONSTANT_UnresolvedString entries and not JVM_CONSTANT_Class
-// entries.
-//
-// Now we can get back to the copying complication. When we copy
-// entries from old_cp to merge_cp, we have to revert any
-// JVM_CONSTANT_Class entries to JVM_CONSTANT_UnresolvedClass entries
-// or verification will fail.
-//
-// It is important to explicitly state that the merging algorithm
-// effectively unresolves JVM_CONSTANT_Class entries that were in the
-// old_cp when they are changed into JVM_CONSTANT_UnresolvedClass
-// entries in the merge_cp. This is done both to make verification
-// happy and to avoid adding more brittleness between RedefineClasses
-// and the constant pool cache. By allowing the constant pool cache
-// implementation to (re)resolve JVM_CONSTANT_UnresolvedClass entries
-// into JVM_CONSTANT_Class entries, we avoid having to embed knowledge
-// about those algorithms in RedefineClasses.
-//
-// Appending unique entries from scratch_cp to merge_cp is straight
-// forward for direct CP entries and most indirect CP entries. For the
-// indirect CP entry type JVM_CONSTANT_NameAndType and for the double-
-// indirect CP entry types, the presence of more than one piece of
-// interesting data makes appending the entries more complicated.
-//
-// For the JVM_CONSTANT_{Double,Float,Integer,Long,Utf8} entry types,
-// the entry is simply copied from scratch_cp to the end of merge_cp.
-// If the index in scratch_cp is different than the destination index
-// in merge_cp, then the change in index value is tracked.
-//
-// Note: the above discussion for the direct CP entries also applies
-// to the JVM_CONSTANT_Unresolved{Class,String} entry types.
-//
-// For the JVM_CONSTANT_{Class,String} entry types, since there is only
-// one data element at the end of the recursion, we know that we have
-// either one or two unique entries. If the JVM_CONSTANT_Utf8 entry is
-// unique then it is appended to merge_cp before the current entry.
-// If the JVM_CONSTANT_Utf8 entry is not unique, then the current entry
-// is updated to refer to the duplicate entry in merge_cp before it is
-// appended to merge_cp. Again, any changes in index values are tracked
-// as needed.
-//
-// Note: the above discussion for JVM_CONSTANT_{Class,String} entry
-// types is theoretical. Since those entry types have already been
-// optimized into JVM_CONSTANT_Unresolved{Class,String} entry types,
-// they are handled as direct CP entries.
-//
-// For the JVM_CONSTANT_NameAndType entry type, since there are two
-// data elements at the end of the recursions, we know that we have
-// between one and three unique entries. Any unique JVM_CONSTANT_Utf8
-// entries are appended to merge_cp before the current entry. For any
-// JVM_CONSTANT_Utf8 entries that are not unique, the current entry is
-// updated to refer to the duplicate entry in merge_cp before it is
-// appended to merge_cp. Again, any changes in index values are tracked
-// as needed.
-//
-// For the JVM_CONSTANT_{Fieldref,InterfaceMethodref,Methodref} entry
-// types, since there are two indirect CP entries and three data
-// elements at the end of the recursions, we know that we have between
-// one and six unique entries. See the JVM_CONSTANT_Fieldref diagram
-// above for an example of all six entries. The uniqueness algorithm
-// for the JVM_CONSTANT_Class and JVM_CONSTANT_NameAndType entries is
-// covered above. Any unique entries are appended to merge_cp before
-// the current entry. For any entries that are not unique, the current
-// entry is updated to refer to the duplicate entry in merge_cp before
-// it is appended to merge_cp. Again, any changes in index values are
-// tracked as needed.
-//
-//
-// Other Details:
-//
-// Details for other parts of RedefineClasses need to be written.
-// This is a placeholder section.
-//
-//
-// Open Issues (in no particular order):
-//
-// - How do we serialize the RedefineClasses() API without deadlocking?
-//
-// - SystemDictionary::parse_stream() was called with a NULL protection
-//   domain since the initial version. This has been changed to pass
-//   the_class->protection_domain(). This change has been tested with
-//   all NSK tests and nothing broke, but what will adding it now break
-//   in ways that we don't test?
-//
-// - GenerateOopMap::rewrite_load_or_store() has a comment in its
-//   (indirect) use of the Relocator class that the max instruction
-//   size is 4 bytes. goto_w and jsr_w are 5 bytes and wide/iinc is
-//   6 bytes. Perhaps Relocator only needs a 4 byte buffer to do
-//   what it does to the bytecodes. More investigation is needed.
-//
-// - java.lang.Object methods can be called on arrays. This is
-//   implemented via the arrayKlassOop vtable which we don't
-//   update. For example, if we redefine java.lang.Object.toString(),
-//   then the new version of the method will not be called for array
-//   objects.
-//
-// - How do we know if redefine_single_class() and the guts of
-//   instanceKlass are out of sync? I don't think this can be
-//   automated, but we should probably order the work in
-//   redefine_single_class() to match the order of field
-//   definitions in instanceKlass. We also need to add some
-//   comments about keeping things in sync.
-//
-// - set_new_constant_pool() is huge and we should consider refactoring
-//   it into smaller chunks of work.
-//
-// - The exception table update code in set_new_constant_pool() defines
-//   const values that are also defined in a local context elsewhere.
-//   The same literal values are also used in elsewhere. We need to
-//   coordinate a cleanup of these constants with Runtime.
-//
+#define RC_ABORT(error) { _result = error; return false; }
 
-class VM_RedefineClasses: public VM_Operation {
+class VM_RedefineClasses: public VM_GC_Operation {
  private:
+
   // These static fields are needed by SystemDictionary::classes_do()
   // facility and the adjust_cpool_cache_and_vtable() helper:
   static objArrayOop     _old_methods;
   static objArrayOop     _new_methods;
-  static methodOop*      _matching_old_methods;
-  static methodOop*      _matching_new_methods;
-  static methodOop*      _deleted_methods;
-  static methodOop*      _added_methods;
+  static int*            _matching_old_methods;
+  static int*            _matching_new_methods;
+  static int*            _deleted_methods;
+  static int*            _added_methods;
   static int             _matching_methods_length;
   static int             _deleted_methods_length;
   static int             _added_methods_length;
   static klassOop        _the_class_oop;
 
+  static int             _revision_number;
+
   // The instance fields are used to pass information from
   // doit_prologue() to doit() and doit_epilogue().
   jint                        _class_count;
@@ -370,36 +70,29 @@
   // _index_map_p contains any entries.
   int                         _index_map_count;
   intArray *                  _index_map_p;
-  // ptr to _class_count scratch_classes
-  instanceKlassHandle *       _scratch_classes;
-  jvmtiError                  _res;
+  GrowableArray<instanceKlassHandle>* _new_classes;
+  GrowableArray<oop>*         _updated_oops;
+  jvmtiError                  _result;
+  int                         _max_redefinition_flags;
 
   // Performance measurement support. These timers do not cover all
   // the work done for JVM/TI RedefineClasses() but they do cover
   // the heavy lifting.
-  elapsedTimer  _timer_rsc_phase1;
-  elapsedTimer  _timer_rsc_phase2;
-  elapsedTimer  _timer_vm_op_prologue;
+  elapsedTimer _timer_total;
+  elapsedTimer _timer_prologue;
+  elapsedTimer _timer_class_linking;
+  elapsedTimer _timer_class_loading;
+  elapsedTimer _timer_check_type;
+  elapsedTimer _timer_prepare_redefinition;
+  elapsedTimer _timer_wait_for_locks;
+  elapsedTimer _timer_redefinition;
+  elapsedTimer _timer_vm_op_epilogue;
 
-  // These routines are roughly in call order unless otherwise noted.
-
-  // Load the caller's new class definition(s) into _scratch_classes.
-  // Constant pool merging work is done here as needed. Also calls
-  // compare_and_normalize_class_versions() to verify the class
-  // definition(s).
+  jvmtiError check_redefinition_allowed(instanceKlassHandle new_class);
+  jvmtiError find_sorted_affected_classes(GrowableArray<instanceKlassHandle> *all_affected_klasses);
+  jvmtiError find_class_bytes(instanceKlassHandle the_class, const unsigned char **class_bytes, jint *class_byte_count, jboolean *not_changed);
   jvmtiError load_new_class_versions(TRAPS);
 
-  // Verify that the caller provided class definition(s) that meet
-  // the restrictions of RedefineClasses. Normalize the order of
-  // overloaded methods as needed.
-  jvmtiError compare_and_normalize_class_versions(
-    instanceKlassHandle the_class, instanceKlassHandle scratch_class);
-
-  // Swap annotations[i] with annotations[j]
-  // Used by compare_and_normalize_class_versions() when normalizing
-  // overloaded methods or changing idnum as when adding or deleting methods.
-  void swap_all_method_annotations(int i, int j, instanceKlassHandle scratch_class);
-
   // Figure out which new methods match old methods in name and signature,
   // which methods have been added, and which are no longer present
   void compute_added_deleted_matching_methods();
@@ -407,96 +100,100 @@
   // Change jmethodIDs to point to the new methods
   void update_jmethod_ids();
 
-  // In addition to marking methods as obsolete, this routine
-  // records which methods are EMCP (Equivalent Module Constant
-  // Pool) in the emcp_methods BitMap and returns the number of
-  // EMCP methods via emcp_method_count_p. This information is
-  // used when information about the previous version of the_class
-  // is squirreled away.
-  void check_methods_and_mark_as_obsolete(BitMap *emcp_methods,
-         int * emcp_method_count_p);
-  void transfer_old_native_function_registrations(instanceKlassHandle the_class);
+  class FindAffectedKlassesClosure : public ObjectClosure {
 
-  // Unevolving classes may point to methods of the_class directly
-  // from their constant pool caches, itables, and/or vtables. We
-  // use the SystemDictionary::classes_do() facility and this helper
-  // to fix up these pointers.
-  static void adjust_cpool_cache_and_vtable(klassOop k_oop, oop loader, TRAPS);
+  private:
+    GrowableArray<instanceKlassHandle> *_original_klasses;
+    GrowableArray<instanceKlassHandle> *_result;
+
+  public:
+    FindAffectedKlassesClosure(GrowableArray<instanceKlassHandle> *original_klasses, GrowableArray<instanceKlassHandle> *result);
+   
+    virtual void do_object(oop obj);
+  };
+
+
+  static jvmtiError do_topological_class_sorting(const jvmtiClassDefinition *class_definitions, int class_count, GrowableArray<instanceKlassHandle> *affected, GrowableArray<instanceKlassHandle> *arr, TRAPS);
 
   // Install the redefinition of a class
-  void redefine_single_class(jclass the_jclass,
-    instanceKlassHandle scratch_class, TRAPS);
+  void redefine_single_class(instanceKlassHandle the_new_class, TRAPS);
 
   // Increment the classRedefinedCount field in the specific instanceKlass
   // and in all direct and indirect subclasses.
   void increment_class_counter(instanceKlass *ik, TRAPS);
 
-  // Support for constant pool merging (these routines are in alpha
-  // order):
-  void append_entry(constantPoolHandle scratch_cp, int scratch_i,
-    constantPoolHandle *merge_cp_p, int *merge_cp_length_p, TRAPS);
-  int find_new_index(int old_index);
-  bool is_unresolved_class_mismatch(constantPoolHandle cp1, int index1,
-    constantPoolHandle cp2, int index2);
-  bool is_unresolved_string_mismatch(constantPoolHandle cp1, int index1,
-    constantPoolHandle cp2, int index2);
-  void map_index(constantPoolHandle scratch_cp, int old_index, int new_index);
-  bool merge_constant_pools(constantPoolHandle old_cp,
-    constantPoolHandle scratch_cp, constantPoolHandle *merge_cp_p,
-    int *merge_cp_length_p, TRAPS);
-  jvmtiError merge_cp_and_rewrite(instanceKlassHandle the_class,
-    instanceKlassHandle scratch_class, TRAPS);
-  u2 rewrite_cp_ref_in_annotation_data(
-    typeArrayHandle annotations_typeArray, int &byte_i_ref,
-    const char * trace_mesg, TRAPS);
-  bool rewrite_cp_refs(instanceKlassHandle scratch_class, TRAPS);
-  bool rewrite_cp_refs_in_annotation_struct(
-    typeArrayHandle class_annotations, int &byte_i_ref, TRAPS);
-  bool rewrite_cp_refs_in_annotations_typeArray(
-    typeArrayHandle annotations_typeArray, int &byte_i_ref, TRAPS);
-  bool rewrite_cp_refs_in_class_annotations(
-    instanceKlassHandle scratch_class, TRAPS);
-  bool rewrite_cp_refs_in_element_value(
-    typeArrayHandle class_annotations, int &byte_i_ref, TRAPS);
-  bool rewrite_cp_refs_in_fields_annotations(
-    instanceKlassHandle scratch_class, TRAPS);
-  void rewrite_cp_refs_in_method(methodHandle method,
-    methodHandle * new_method_p, TRAPS);
-  bool rewrite_cp_refs_in_methods(instanceKlassHandle scratch_class, TRAPS);
-  bool rewrite_cp_refs_in_methods_annotations(
-    instanceKlassHandle scratch_class, TRAPS);
-  bool rewrite_cp_refs_in_methods_default_annotations(
-    instanceKlassHandle scratch_class, TRAPS);
-  bool rewrite_cp_refs_in_methods_parameter_annotations(
-    instanceKlassHandle scratch_class, TRAPS);
-  void rewrite_cp_refs_in_stack_map_table(methodHandle method, TRAPS);
-  void rewrite_cp_refs_in_verification_type_info(
-         address& stackmap_addr_ref, address stackmap_end, u2 frame_i,
-         u1 frame_size, TRAPS);
-  void set_new_constant_pool(instanceKlassHandle scratch_class,
-    constantPoolHandle scratch_cp, int scratch_cp_length, bool shrink, TRAPS);
 
   void flush_dependent_code(instanceKlassHandle k_h, TRAPS);
 
-  static void check_class(klassOop k_oop, oop initiating_loader, TRAPS) PRODUCT_RETURN;
+  static void check_class(klassOop k_oop,/* oop initiating_loader,*/ TRAPS) PRODUCT_RETURN;
 
-  static void dump_methods()   PRODUCT_RETURN;
+  static void adjust_cpool_cache(klassOop k_oop, oop initiating_loader, TRAPS);
+
+#ifdef ASSERT
+  static void verify_classes(klassOop k_oop, oop initiating_loader, TRAPS);
+#endif
+
+  int calculate_redefinition_flags(instanceKlassHandle new_version);
+  void calculate_instance_update_information(klassOop new_version);
+  void check_methods_and_mark_as_obsolete(BitMap *emcp_methods, int * emcp_method_count_p);
+
+  static void calculate_type_check_information(klassOop k);
+  static void clear_type_check_information(klassOop k);
 
  public:
-  VM_RedefineClasses(jint class_count,
-                     const jvmtiClassDefinition *class_defs,
-                     JvmtiClassLoadKind class_load_kind);
-  VMOp_Type type() const { return VMOp_RedefineClasses; }
+  VM_RedefineClasses(jint class_count, const jvmtiClassDefinition *class_defs, JvmtiClassLoadKind class_load_kind);
+  virtual ~VM_RedefineClasses();
+  
+  bool check_arguments();
   bool doit_prologue();
   void doit();
   void doit_epilogue();
+  void rollback();
 
-  bool allow_nested_vm_operations() const        { return true; }
-  jvmtiError check_error()                       { return _res; }
+  jvmtiError check_exception() const;
+  VMOp_Type type() const                         { return VMOp_RedefineClasses; }
+  bool skip_operation() const                    { return false; }
+  bool allow_nested_vm_operations() const        { return true;  }
+  jvmtiError check_error()                       { return _result;  }
+
+  void update_active_methods();
+
+  // Checks for type consistency after hierarchy change
+  bool check_type_consistency();
+  void calculate_type_check_information();
+  bool check_field_value_types();
+  void clear_type_check_information();
+  bool check_method_stacks();
+  bool check_loaded_methods();
+  bool check_method(methodOop method);
+  static Symbol* signature_to_class_name(Symbol* signature);
+
+  void method_forwarding();
+
+  void update_array_classes_to_newest_version(klassOop smallest_dimension);
 
   // Modifiable test must be shared between IsModifiableClass query
   // and redefine implementation
   static bool is_modifiable_class(oop klass_mirror);
+
+  // Method used during garbage collection, the VM operation must iterate over all oops.
+  void oops_do(OopClosure* f);
+
+  // Utility methods for transfering field access flags
+
+  static void transfer_special_access_flags(fieldDescriptor *from, fieldDescriptor *to);
+  static void update_klass_field_access_flag(fieldDescriptor *fd);
+
+  void transfer_old_native_function_registrations(instanceKlassHandle the_class);
+
+  void lock_threads();
+  void unlock_threads();
+
+  template <class T> static void do_oop_work(T* p);
+
+  static void swap_marks(oop first, oop second);
+
 };
 
 #endif // SHARE_VM_PRIMS_JVMTIREDEFINECLASSES_HPP
+
diff --git a/src/share/vm/prims/methodComparator.cpp b/src/share/vm/prims/methodComparator.cpp
--- a/src/share/vm/prims/methodComparator.cpp
+++ b/src/share/vm/prims/methodComparator.cpp
@@ -65,6 +65,37 @@
     if (! args_same(c_old, c_new))
       return false;
   }
+
+  // DCEVM: Added exception table comparison to EMCP comparison
+
+  typeArrayOop ex_old = old_method->constMethod()->exception_table();
+  typeArrayOop ex_new = new_method->constMethod()->exception_table();
+
+  if (ex_old == NULL && ex_new != NULL) return false;
+  if (ex_old != NULL && ex_new == NULL) return false;
+
+  if (ex_old != NULL && ex_new != NULL && ex_old->length() == ex_new->length()) {
+    // Per entry:
+    /* start    */     
+    /* limit    */      
+    /* goto pc  */     
+    /* cp index */
+    for (int i=0; i<ex_old->length(); i++) {
+      int old_val = ex_old->int_at(i);
+      int new_val = ex_new->int_at(i);
+      if ((i + 1) % 4 == 0) {
+        if (old_val == 0 || new_val == 0) {
+          if (old_val != new_val) return false;
+        } else if ((_old_cp->klass_at_noresolve(old_val) != _new_cp->klass_at_noresolve(new_val)))
+          return false;
+      } else {
+        if (old_val != new_val) {
+          return false;
+        }
+      }
+    }
+  }
+
   return true;
 }
 
diff --git a/src/share/vm/prims/nativeLookup.cpp b/src/share/vm/prims/nativeLookup.cpp
--- a/src/share/vm/prims/nativeLookup.cpp
+++ b/src/share/vm/prims/nativeLookup.cpp
@@ -35,6 +35,7 @@
 #include "oops/symbol.hpp"
 #include "prims/jvm_misc.hpp"
 #include "prims/nativeLookup.hpp"
+#include "prims/jvmtiRedefineClasses.hpp"
 #include "runtime/arguments.hpp"
 #include "runtime/handles.inline.hpp"
 #include "runtime/javaCalls.hpp"
@@ -53,7 +54,6 @@
 # include "os_bsd.inline.hpp"
 #endif
 
-
 static void mangle_name_on(outputStream* st, Symbol* name, int begin, int end) {
   char* bytes = (char*)name->bytes() + begin;
   char* end_bytes = (char*)name->bytes() + end;
@@ -136,6 +136,40 @@
   { CC"Java_sun_misc_Perf_registerNatives",                        NULL, FN_PTR(JVM_RegisterPerfMethods)         }
 };
 
+// Helper function to call redefineClasses from Java Code
+JVM_ENTRY(int, JVM_RedefineClassesHelper(JNIEnv *env, jclass cb, jclass target, jbyteArray bytes))
+  ResourceMark rm(THREAD);
+
+  JavaThread* current_thread = JavaThread::current();
+  jbyte* bytecodes = NULL;
+  const int class_count = 1;
+  jvmtiClassDefinition* class_definitions = NEW_RESOURCE_ARRAY(jvmtiClassDefinition, class_count);
+  
+  {
+     ThreadToNativeFromVM ttnfv(thread);
+     jboolean is_copy = JNI_FALSE;
+     bytecodes = env->GetByteArrayElements(bytes, &is_copy);
+     class_definitions[0].klass = target;
+     class_definitions[0].class_byte_count = env->GetArrayLength(bytes);
+     class_definitions[0].class_bytes = (unsigned char*)bytecodes;
+  }
+
+  VM_RedefineClasses op(class_count, class_definitions, jvmti_class_load_kind_retransform);
+  VMThread::execute(&op);
+  int result = op.check_error();
+
+  {
+    ThreadToNativeFromVM ttnfv(thread);
+    if (env->ExceptionOccurred()) {
+      return -1;
+    }
+    env->ReleaseByteArrayElements(bytes, bytecodes, 0);
+  }
+
+ return result;
+JVM_END
+
+
 static address lookup_special_native(char* jni_name) {
   int i = !JDK_Version::is_gte_jdk14x_version() ? 0 : 2;  // see comment in lookup_special_native_methods
   int count = sizeof(lookup_special_native_methods) / sizeof(JNINativeMethod);
@@ -175,6 +209,9 @@
       return entry;
     }
   }
+  if(strstr(jni_name, "Java_at_ssw_hotswap_ClassRedefinition_redefineClasses") != NULL) {
+		return CAST_FROM_FN_PTR(address, JVM_RedefineClassesHelper);
+  }
 
   // Otherwise call static method findNative in ClassLoader
   KlassHandle   klass (THREAD, SystemDictionary::ClassLoader_klass());
diff --git a/src/share/vm/runtime/arguments.cpp b/src/share/vm/runtime/arguments.cpp
--- a/src/share/vm/runtime/arguments.cpp
+++ b/src/share/vm/runtime/arguments.cpp
@@ -1747,6 +1747,15 @@
     status = false;
   }
 
+  // (tw) Must use serial GC
+  if (!UseSerialGC && i >= 1) {
+    jio_fprintf(defaultStream::error_stream(),
+      "Must use the serial GC in the Dynamic Code Evolution VM\n");
+    status = false;
+  } else {
+    UseSerialGC = true;
+  }
+
   return status;
 }
 
diff --git a/src/share/vm/runtime/deoptimization.cpp b/src/share/vm/runtime/deoptimization.cpp
--- a/src/share/vm/runtime/deoptimization.cpp
+++ b/src/share/vm/runtime/deoptimization.cpp
@@ -595,6 +595,38 @@
   // Cleanup thread deopt data
   cleanup_deopt_info(thread, array);
 
+  // (tw) Redefinition support: Check if we need to transfer method execution points to new versions
+  {
+    ResourceMark res_mark;
+
+    // Verify that the just-unpacked frames match the interpreter's
+    // notions of expression stack and locals
+    vframeArray* cur_array = thread->vframe_array_last();
+    RegisterMap rm(thread, false);
+    rm.set_include_argument_oops(false);
+    for (int i = 0; i < cur_array->frames(); i++) {
+      vframeArrayElement* el = cur_array->element(i);
+      frame* frame = el->iframe();
+      guarantee(frame->is_interpreted_frame(), "Wrong frame type");
+      RegisterMap reg_map(thread);
+      vframe* vf = vframe::new_vframe(frame, &reg_map, thread);
+      interpretedVFrame *iframe = (interpretedVFrame *)vf;
+      methodOop method = iframe->method();
+      int bci = iframe->bci();
+      method = method->newest_version();
+      iframe->set_method(method, bci);
+
+      methodOop forward_method = method->forward_method();
+      if (forward_method != NULL && method->is_in_code_section(bci)) {
+        int new_bci = method->calculate_forward_bci(bci, forward_method);
+        if (TraceRedefineClasses >= 2) {
+          tty->print_cr("Transfering execution of %s to new method old_bci=%d new_bci=%d", forward_method->name()->as_C_string(), bci, new_bci);
+        }
+        iframe->set_method(forward_method, new_bci);
+      }
+    }
+  }
+
 #ifndef PRODUCT
   if (VerifyStack) {
     ResourceMark res_mark;
diff --git a/src/share/vm/runtime/frame.cpp b/src/share/vm/runtime/frame.cpp
--- a/src/share/vm/runtime/frame.cpp
+++ b/src/share/vm/runtime/frame.cpp
@@ -403,6 +403,12 @@
   *interpreter_frame_method_addr() = method;
 }
 
+// (tw) Sets constant pool cache oop
+void frame::interpreter_frame_set_cache(constantPoolCacheOop cp) {
+  assert(is_interpreted_frame(), "interpreted frame expected");
+  *interpreter_frame_cache_addr() = cp;
+}
+
 void frame::interpreter_frame_set_bcx(intptr_t bcx) {
   assert(is_interpreted_frame(), "Not an interpreted frame");
   if (ProfileInterpreter) {
@@ -418,19 +424,27 @@
           // The bcx was just converted from bci to bcp.
           // Convert the mdx in parallel.
           methodDataOop mdo = interpreter_frame_method()->method_data();
-          assert(mdo != NULL, "");
-          int mdi = mdx - 1; // We distinguish valid mdi from zero by adding one.
-          address mdp = mdo->di_to_dp(mdi);
-          interpreter_frame_set_mdx((intptr_t)mdp);
+          if (mdo == NULL) {
+            interpreter_frame_set_mdx(0);
+          } else {
+            assert(mdo != NULL, "");
+            int mdi = mdx - 1; // We distinguish valid mdi from zero by adding one.
+            address mdp = mdo->di_to_dp(mdi);
+            interpreter_frame_set_mdx((intptr_t)mdp);
+          }
         }
       } else {
         if (is_now_bci) {
           // The bcx was just converted from bcp to bci.
           // Convert the mdx in parallel.
           methodDataOop mdo = interpreter_frame_method()->method_data();
-          assert(mdo != NULL, "");
-          int mdi = mdo->dp_to_di((address)mdx);
-          interpreter_frame_set_mdx((intptr_t)mdi + 1); // distinguish valid from 0.
+          if (mdo == NULL) {
+            interpreter_frame_set_mdx(0);
+          } else {
+            assert(mdo != NULL, "");
+            int mdi = mdo->dp_to_di((address)mdx);
+            interpreter_frame_set_mdx((intptr_t)mdi + 1); // distinguish valid from 0.
+          }
         }
       }
     }
diff --git a/src/share/vm/runtime/frame.hpp b/src/share/vm/runtime/frame.hpp
--- a/src/share/vm/runtime/frame.hpp
+++ b/src/share/vm/runtime/frame.hpp
@@ -346,6 +346,7 @@
   // Method & constant pool cache
   methodOop interpreter_frame_method() const;
   void interpreter_frame_set_method(methodOop method);
+  void interpreter_frame_set_cache(constantPoolCacheOop method);
   methodOop* interpreter_frame_method_addr() const;
   constantPoolCacheOop* interpreter_frame_cache_addr() const;
 #ifdef PPC
diff --git a/src/share/vm/runtime/globals.hpp b/src/share/vm/runtime/globals.hpp
--- a/src/share/vm/runtime/globals.hpp
+++ b/src/share/vm/runtime/globals.hpp
@@ -1309,9 +1309,23 @@
   product(bool, StressLdcRewrite, false,                                    \
           "Force ldc -> ldc_w rewrite during RedefineClasses")              \
                                                                             \
+  product(bool, UseMethodForwardPoints, false,                              \
+          "Use method forward points")                                      \
+                                                                            \
+  product(intx, MethodForwardPointsMaxLocals, 300,                          \
+          "Maximum number of locals in forwarding method")                  \
+                                                                            \
+  product(intx, MethodForwardPointsMaxStack, 300,                           \
+          "Maximum number of stack slots in forwarding method")             \
+                                                                            \
   product(intx, TraceRedefineClasses, 0,                                    \
           "Trace level for JVMTI RedefineClasses")                          \
                                                                             \
+  product(bool, TimeRedefineClasses, false,                                 \
+          "Measure timing for JVMTI RedefineClasses")                       \
+                                                                            \
+  product(bool, AllowAdvancedClassRedefinition, true,                       \
+          "Allow advanced class redefinition beyond swapping method bodies")\
   develop(bool, StressMethodComparator, false,                              \
           "run the MethodComparator on all loaded methods")                 \
                                                                             \
diff --git a/src/share/vm/runtime/interfaceSupport.hpp b/src/share/vm/runtime/interfaceSupport.hpp
--- a/src/share/vm/runtime/interfaceSupport.hpp
+++ b/src/share/vm/runtime/interfaceSupport.hpp
@@ -296,7 +296,7 @@
   ThreadToNativeFromVM(JavaThread *thread) : ThreadStateTransition(thread) {
     // We are leaving the VM at this point and going directly to native code.
     // Block, if we are in the middle of a safepoint synchronization.
-    assert(!thread->owns_locks(), "must release all locks when leaving VM");
+    assert(!thread->owns_locks_but_redefine_classes_lock(), "must release all locks when leaving VM");
     thread->frame_anchor()->make_walkable(thread);
     trans_and_fence(_thread_in_vm, _thread_in_native);
     // Check for pending. async. exceptions or suspends.
diff --git a/src/share/vm/runtime/javaCalls.cpp b/src/share/vm/runtime/javaCalls.cpp
--- a/src/share/vm/runtime/javaCalls.cpp
+++ b/src/share/vm/runtime/javaCalls.cpp
@@ -60,7 +60,7 @@
   bool clear_pending_exception = true;
 
   guarantee(thread->is_Java_thread(), "crucial check - the VM thread cannot and must not escape to Java code");
-  assert(!thread->owns_locks(), "must release all locks when leaving VM");
+  assert(!thread->owns_locks_but_redefine_classes_lock(), "must release all locks when leaving VM");
   guarantee(!thread->is_Compiler_thread(), "cannot make java calls from the compiler");
   _result   = result;
 
diff --git a/src/share/vm/runtime/jniHandles.cpp b/src/share/vm/runtime/jniHandles.cpp
--- a/src/share/vm/runtime/jniHandles.cpp
+++ b/src/share/vm/runtime/jniHandles.cpp
@@ -112,6 +112,10 @@
 }
 
 jmethodID JNIHandles::make_jmethod_id(methodHandle mh) {
+  if (mh->newest_version() != mh()) {
+    methodHandle mh_new(Thread::current(), mh()->newest_version());
+    return (jmethodID) make_weak_global(mh_new);
+  }
   return (jmethodID) make_weak_global(mh);
 }
 
diff --git a/src/share/vm/runtime/mutex.cpp b/src/share/vm/runtime/mutex.cpp
--- a/src/share/vm/runtime/mutex.cpp
+++ b/src/share/vm/runtime/mutex.cpp
@@ -1227,7 +1227,7 @@
     // in increasing rank order (modulo any native ranks)
     for (tmp = locks; tmp != NULL; tmp = tmp->next()) {
       if (tmp->next() != NULL) {
-        assert(tmp->rank() == Mutex::native ||
+        assert(tmp->rank() == Mutex::native || tmp->rank() == Mutex::redefine_classes ||
                tmp->rank() <= tmp->next()->rank(), "mutex rank anomaly?");
       }
     }
@@ -1247,7 +1247,7 @@
     // in increasing rank order (modulo any native ranks)
     for (tmp = locks; tmp != NULL; tmp = tmp->next()) {
       if (tmp->next() != NULL) {
-        assert(tmp->rank() == Mutex::native ||
+        assert(tmp->rank() == Mutex::native || tmp->rank() == Mutex::redefine_classes ||
                tmp->rank() <= tmp->next()->rank(), "mutex rank anomaly?");
       }
     }
@@ -1310,6 +1310,7 @@
       //   already hold Terminator_lock - may happen because of periodic safepoints
       if (this->rank() != Mutex::native &&
           this->rank() != Mutex::suspend_resume &&
+          this->rank() != Mutex::redefine_classes && 
           locks != NULL && locks->rank() <= this->rank() &&
           !SafepointSynchronize::is_at_safepoint() &&
           this != Interrupt_lock && this != ProfileVM_lock &&
diff --git a/src/share/vm/runtime/mutex.hpp b/src/share/vm/runtime/mutex.hpp
--- a/src/share/vm/runtime/mutex.hpp
+++ b/src/share/vm/runtime/mutex.hpp
@@ -109,7 +109,8 @@
        barrier     = safepoint      +   1,
        nonleaf     = barrier        +   1,
        max_nonleaf = nonleaf        + 900,
-       native      = max_nonleaf    +   1
+       native      = max_nonleaf    +   1,
+       redefine_classes = native    +   1
   };
 
   // The WaitSet and EntryList linked lists are composed of ParkEvents.
diff --git a/src/share/vm/runtime/mutexLocker.cpp b/src/share/vm/runtime/mutexLocker.cpp
--- a/src/share/vm/runtime/mutexLocker.cpp
+++ b/src/share/vm/runtime/mutexLocker.cpp
@@ -49,6 +49,7 @@
 // Consider using GCC's __read_mostly.
 
 Mutex*   Patching_lock                = NULL;
+Mutex*   RedefineClasses_lock         = NULL;
 Monitor* SystemDictionary_lock        = NULL;
 Mutex*   PackageTable_lock            = NULL;
 Mutex*   CompiledIC_lock              = NULL;
@@ -90,6 +91,7 @@
 Mutex*   DirtyCardQ_FL_lock           = NULL;
 Monitor* DirtyCardQ_CBL_mon           = NULL;
 Mutex*   Shared_DirtyCardQ_lock       = NULL;
+Monitor* RedefinitionSync_lock        = NULL;
 Mutex*   ParGCRareEvent_lock          = NULL;
 Mutex*   EvacFailureStack_lock        = NULL;
 Mutex*   DerivedPointerTableGC_lock   = NULL;
@@ -205,6 +207,7 @@
     def(HotCardCache_lock          , Mutex  , special  ,   true );
     def(EvacFailureStack_lock      , Mutex  , nonleaf  ,   true );
   }
+  def(RedefinitionSync_lock        , Monitor  , leaf     ,   false );
   def(ParGCRareEvent_lock          , Mutex  , leaf     ,   true );
   def(DerivedPointerTableGC_lock   , Mutex,   leaf,        true );
   def(CodeCache_lock               , Mutex  , special,     true );
@@ -279,6 +282,7 @@
   def(Debug2_lock                  , Mutex  , nonleaf+4,   true );
   def(Debug3_lock                  , Mutex  , nonleaf+4,   true );
   def(ProfileVM_lock               , Monitor, nonleaf+4,   false); // used for profiling of the VMThread
+  def(RedefineClasses_lock         , Mutex, nonleaf+7,     false ); // for ensuring that class redefinition is not done in parallel
   def(CompileThread_lock           , Monitor, nonleaf+5,   false );
 
   def(JfrQuery_lock                , Monitor, nonleaf,     true);  // JFR locks, keep these in consecutive order
diff --git a/src/share/vm/runtime/mutexLocker.hpp b/src/share/vm/runtime/mutexLocker.hpp
--- a/src/share/vm/runtime/mutexLocker.hpp
+++ b/src/share/vm/runtime/mutexLocker.hpp
@@ -43,6 +43,8 @@
 // Mutexes used in the VM.
 
 extern Mutex*   Patching_lock;                   // a lock used to guard code patching of compiled code
+extern Monitor* RedefinitionSync_lock;           // a lock on synchronized class redefinition
+extern Mutex*   RedefineClasses_lock;            // a lock on class redefinition
 extern Monitor* SystemDictionary_lock;           // a lock on the system dictonary
 extern Mutex*   PackageTable_lock;               // a lock on the class loader package table
 extern Mutex*   CompiledIC_lock;                 // a lock used to guard compiled IC patching and access
diff --git a/src/share/vm/runtime/reflection.cpp b/src/share/vm/runtime/reflection.cpp
--- a/src/share/vm/runtime/reflection.cpp
+++ b/src/share/vm/runtime/reflection.cpp
@@ -469,7 +469,8 @@
   // sun/reflect/MagicAccessorImpl subclasses to succeed trivially.
   if (   JDK_Version::is_gte_jdk14x_version()
       && UseNewReflection
-      && Klass::cast(current_class)->is_subclass_of(SystemDictionary::reflect_MagicAccessorImpl_klass())) {
+      && (Klass::cast(current_class)->is_subclass_of(SystemDictionary::reflect_MagicAccessorImpl_klass()) ||
+      Klass::cast(current_class)->is_subclass_of(SystemDictionary::reflect_MagicAccessorImpl_klass()->klass_part()->newest_version()))) {
     return true;
   }
 
@@ -525,6 +526,12 @@
                                      AccessFlags access,
                                      bool classloader_only,
                                      bool protected_restriction) {
+
+  // (tw) Decide accessibility based on active version
+  if (current_class != NULL) {
+    current_class = current_class->klass_part()->active_version();
+  }
+  
   // Verify that current_class can access a field of field_class, where that
   // field's access bits are "access".  We assume that we've already verified
   // that current_class can access field_class.
@@ -566,7 +573,8 @@
   // sun/reflect/MagicAccessorImpl subclasses to succeed trivially.
   if (   JDK_Version::is_gte_jdk14x_version()
       && UseNewReflection
-      && Klass::cast(current_class)->is_subclass_of(SystemDictionary::reflect_MagicAccessorImpl_klass())) {
+      && (Klass::cast(current_class)->is_subclass_of(SystemDictionary::reflect_MagicAccessorImpl_klass()) ||
+      Klass::cast(current_class)->is_subclass_of(SystemDictionary::reflect_MagicAccessorImpl_klass()->klass_part()->newest_version()))) {
     return true;
   }
 
diff --git a/src/share/vm/runtime/sharedRuntime.cpp b/src/share/vm/runtime/sharedRuntime.cpp
--- a/src/share/vm/runtime/sharedRuntime.cpp
+++ b/src/share/vm/runtime/sharedRuntime.cpp
@@ -1139,7 +1139,20 @@
   if (JvmtiExport::can_hotswap_or_post_breakpoint()) {
     int retry_count = 0;
     while (!HAS_PENDING_EXCEPTION && callee_method->is_old() &&
-           callee_method->method_holder() != SystemDictionary::Object_klass()) {
+           callee_method->method_holder()->klass_part()->newest_version() != SystemDictionary::Object_klass()->klass_part()->newest_version()) {
+
+      // DCEVM: If we are executing an old method, this is OK!
+      {
+        ResourceMark rm(thread);
+        RegisterMap cbl_map(thread, false);
+        frame caller_frame = thread->last_frame().sender(&cbl_map);
+
+        CodeBlob* caller_cb = caller_frame.cb();
+        guarantee(caller_cb != NULL && caller_cb->is_nmethod(), "must be called from nmethod");
+        nmethod* caller_nm = caller_cb->as_nmethod_or_null();
+        if (caller_nm->method()->is_old()) break;
+      }
+
       // If has a pending exception then there is no need to re-try to
       // resolve this method.
       // If the method has been redefined, we need to try again.
diff --git a/src/share/vm/runtime/thread.cpp b/src/share/vm/runtime/thread.cpp
--- a/src/share/vm/runtime/thread.cpp
+++ b/src/share/vm/runtime/thread.cpp
@@ -212,6 +212,8 @@
   set_self_raw_id(0);
   set_lgrp_id(-1);
 
+  _redefine_classes_mutex = new Mutex(Mutex::redefine_classes, "redefine classes lock", false);
+
   // allocated data structures
   set_osthread(NULL);
   set_resource_area(new ResourceArea());
@@ -246,6 +248,7 @@
   omFreeProvision = 32 ;
   omInUseList = NULL ;
   omInUseCount = 0 ;
+  _pretend_new_universe = false;
 
 #ifdef ASSERT
   _visited_for_critical_count = false;
@@ -857,6 +860,15 @@
   return false;
 }
 
+bool Thread::owns_locks_but_redefine_classes_lock() const {
+  for(Monitor *cur = _owned_locks; cur; cur = cur->next()) {
+    if (cur != RedefineClasses_lock && cur->rank() != Mutex::redefine_classes) {
+      return true;
+    }
+  }
+  return false;
+}
+
 
 #endif
 
@@ -1507,7 +1519,7 @@
   ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm);
 
   assert(JavaThread::current() == this, "sanity check");
-  assert(!Thread::current()->owns_locks(), "sanity check");
+  assert(!Thread::current()->owns_locks_but_redefine_classes_lock(), "sanity check");
 
   DTRACE_THREAD_PROBE(start, this);
 
@@ -3045,7 +3057,7 @@
 
 // Create a CompilerThread
 CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters)
-: JavaThread(&compiler_thread_entry) {
+: JavaThread(&compiler_thread_entry), _should_bailout(false) {
   _env   = NULL;
   _log   = NULL;
   _task  = NULL;
@@ -3053,6 +3065,7 @@
   _counters = counters;
   _buffer_blob = NULL;
   _scanned_nmethod = NULL;
+  _compilation_mutex = new Mutex(Mutex::redefine_classes, "compilationMutex", false);
 
 #ifndef PRODUCT
   _ideal_graph_printer = NULL;
@@ -3082,6 +3095,7 @@
 int         Threads::_number_of_non_daemon_threads = 0;
 int         Threads::_return_code = 0;
 size_t      JavaThread::_stack_size_at_create = 0;
+bool        Threads::_wait_at_instrumentation_entry = false;
 
 // All JavaThreads
 #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next())
diff --git a/src/share/vm/runtime/thread.hpp b/src/share/vm/runtime/thread.hpp
--- a/src/share/vm/runtime/thread.hpp
+++ b/src/share/vm/runtime/thread.hpp
@@ -197,11 +197,14 @@
   void enter_signal_handler() { _num_nested_signal++; }
   void leave_signal_handler() { _num_nested_signal--; }
   bool is_inside_signal_handler() const { return _num_nested_signal > 0; }
+  Mutex* redefine_classes_mutex() { return _redefine_classes_mutex; }
 
  private:
   // Debug tracing
   static void trace(const char* msg, const Thread* const thread) PRODUCT_RETURN;
 
+  Mutex* _redefine_classes_mutex;
+
   // Active_handles points to a block of handles
   JNIHandleBlock* _active_handles;
 
@@ -522,10 +525,15 @@
   uintptr_t        _self_raw_id;      // used by get_thread (mutable)
   int              _lgrp_id;
 
+
+  bool             _pretend_new_universe;
+
  public:
   // Stack overflow support
   address stack_base() const           { assert(_stack_base != NULL,"Sanity check"); return _stack_base; }
 
+  void    set_pretend_new_universe(bool b) { if (_pretend_new_universe != b) { if (TraceRedefineClasses >= 5) tty->print_cr("Changing pretend universe to %d", (int)b); _pretend_new_universe = b; } }
+  bool    pretend_new_universe() { return _pretend_new_universe; }
   void    set_stack_base(address base) { _stack_base = base; }
   size_t  stack_size() const           { return _stack_size; }
   void    set_stack_size(size_t size)  { _stack_size = size; }
@@ -563,6 +571,7 @@
   void print_owned_locks() const                 { print_owned_locks_on(tty);    }
   Monitor* owned_locks() const                   { return _owned_locks;          }
   bool owns_locks() const                        { return owned_locks() != NULL; }
+  bool owns_locks_but_redefine_classes_lock() const;
   bool owns_locks_but_compiled_lock() const;
 
   // Deadlock detection
@@ -1745,6 +1754,8 @@
   CompileTask*  _task;
   CompileQueue* _queue;
   BufferBlob*   _buffer_blob;
+  bool          _should_bailout;
+  Mutex*        _compilation_mutex;
 
   nmethod*      _scanned_nmethod;  // nmethod being scanned by the sweeper
 
@@ -1754,12 +1765,16 @@
 
   CompilerThread(CompileQueue* queue, CompilerCounters* counters);
 
+  bool should_bailout() const                    { return _should_bailout; }
+  void set_should_bailout(bool b)                { _should_bailout = false; }
+
   bool is_Compiler_thread() const                { return true; }
   // Hide this compiler thread from external view.
   bool is_hidden_from_external_view() const      { return true; }
 
   CompileQueue* queue()                          { return _queue; }
   CompilerCounters* counters()                   { return _counters; }
+  Mutex *compilation_mutex()                      { return _compilation_mutex; }
 
   // Get/set the thread's compilation environment.
   ciEnv*        env()                            { return _env; }
@@ -1814,6 +1829,7 @@
   static int         _number_of_threads;
   static int         _number_of_non_daemon_threads;
   static int         _return_code;
+  static bool        _wait_at_instrumentation_entry;
 
  public:
   // Thread management
@@ -1825,6 +1841,9 @@
   static JavaThread* first()                     { return _thread_list; }
   static void threads_do(ThreadClosure* tc);
 
+  static bool wait_at_instrumentation_entry() { return _wait_at_instrumentation_entry; }
+  static void set_wait_at_instrumentation_entry(bool b) { _wait_at_instrumentation_entry = b; }
+
   // Initializes the vm and creates the vm thread
   static jint create_vm(JavaVMInitArgs* args, bool* canTryAgain);
   static void convert_vm_init_libraries_to_agents();
diff --git a/src/share/vm/runtime/vframe.cpp b/src/share/vm/runtime/vframe.cpp
--- a/src/share/vm/runtime/vframe.cpp
+++ b/src/share/vm/runtime/vframe.cpp
@@ -253,6 +253,46 @@
   return fr().interpreter_frame_method();
 }
 
+// (tw) Sets interpreter frame method.
+void interpretedVFrame::set_method(methodOop new_method, int new_bci) {
+  methodOop old_method = fr().interpreter_frame_method();
+  int old_stack_size = fr().interpreter_frame_expression_stack_size();
+  if (old_method == new_method) return;
+  u_char *old_bcp = bcp();
+  int old_bci = bci();
+  fr().interpreter_frame_set_method(new_method);
+  fr().interpreter_frame_set_cache(new_method->constants()->cache());
+  u_char *new_bcp = new_method->code_base() + new_bci;
+  assert(new_method->bcp_from(new_bci) == new_bcp, "");
+
+  set_bcp(new_bcp);
+
+  Bytecodes::Code code = Bytecodes::java_code_at(old_method, old_bcp);
+  assert(Bytecodes::java_code_at(new_method, new_bcp) == code, "must have same bytecode at this position");
+
+  switch (code) {
+    case Bytecodes::_invokevirtual  :
+    case Bytecodes::_invokespecial  :
+    case Bytecodes::_invokestatic   :
+    case Bytecodes::_invokeinterface: {
+      int old_index = Bytes::get_native_u2(old_bcp+1);
+      int new_index = Bytes::get_native_u2(new_bcp+1);
+      new_method->constants()->cache()->entry_at(new_index)->copy_from(old_method->constants()->cache()->entry_at(old_index));
+      break;
+    }
+
+    case Bytecodes::_invokedynamic: {
+      int old_index = Bytes::get_native_u4(old_bcp+1);
+      int new_index = Bytes::get_native_u4(new_bcp+1);
+      new_method->constants()->cache()->secondary_entry_at(new_index)->copy_from(old_method->constants()->cache()->secondary_entry_at(old_index));
+      break;
+    }
+  }
+
+  int new_stack_size = fr().interpreter_frame_expression_stack_size();
+  assert(new_method->validate_bci_from_bcx((intptr_t)new_bcp) == new_bci, "");
+}
+
 StackValueCollection* interpretedVFrame::locals() const {
   int length = method()->max_locals();
 
diff --git a/src/share/vm/runtime/vframe.hpp b/src/share/vm/runtime/vframe.hpp
--- a/src/share/vm/runtime/vframe.hpp
+++ b/src/share/vm/runtime/vframe.hpp
@@ -163,6 +163,7 @@
   StackValueCollection*        locals()         const;
   StackValueCollection*        expressions()    const;
   GrowableArray<MonitorInfo*>* monitors()       const;
+  void                         set_method(methodOop method, int new_bci);
 
   void set_locals(StackValueCollection* values) const;
 
diff --git a/src/share/vm/runtime/vmThread.cpp b/src/share/vm/runtime/vmThread.cpp
--- a/src/share/vm/runtime/vmThread.cpp
+++ b/src/share/vm/runtime/vmThread.cpp
@@ -671,6 +671,9 @@
 void VMThread::oops_do(OopClosure* f, CodeBlobClosure* cf) {
   Thread::oops_do(f, cf);
   _vm_queue->oops_do(f);
+  if (_cur_vm_operation != NULL) {
+    _cur_vm_operation->oops_do(f);
+  }
 }
 
 //------------------------------------------------------------------------------------------------------------------
diff --git a/src/share/vm/utilities/exceptions.cpp b/src/share/vm/utilities/exceptions.cpp
--- a/src/share/vm/utilities/exceptions.cpp
+++ b/src/share/vm/utilities/exceptions.cpp
@@ -251,6 +251,8 @@
   assert(thread->is_Java_thread(), "can only be called by a Java thread");
   assert(!thread->has_pending_exception(), "already has exception");
 
+  bool old_pretend_value = Thread::current()->pretend_new_universe();
+  Thread::current()->set_pretend_new_universe(false);
   Handle h_exception;
 
   // Resolve exception klass
@@ -298,6 +300,8 @@
     h_exception = Handle(thread, thread->pending_exception());
     thread->clear_pending_exception();
   }
+
+  Thread::current()->set_pretend_new_universe(old_pretend_value);
   return h_exception;
 }
 
diff --git a/src/share/vm/utilities/growableArray.hpp b/src/share/vm/utilities/growableArray.hpp
--- a/src/share/vm/utilities/growableArray.hpp
+++ b/src/share/vm/utilities/growableArray.hpp
@@ -135,6 +135,33 @@
     assert(on_stack(), "fast ResourceObj path only");
     return (void*)resource_allocate_bytes(thread, elementSize * _max);
   }
+
+};
+
+template<class E, class F> class Pair : public StackObj
+{
+private:
+  E _left;
+  F _right;
+
+public:
+
+  Pair() {
+
+  }
+
+  Pair(E left, F right) {
+    this->_left = left;
+    this->_right = right;
+  }
+
+  E left() {
+    return _left;
+  }
+
+  F right() {
+    return _right;
+  }
 };
 
 template<class E> class GrowableArray : public GenericGrowableArray {