Merge pull request #160 from drujd/8u201-and-8u202

8u201 and 8u202

4 files changed, 3934 insertions, 8 deletions

diff --git a/gradle.properties b/gradle.properties
index 207a1293..615eedd1 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -52,4 +52,6 @@ targetJre=build/jre
 #hotspotTag=jdk8u144-b01
 #hotspotTag=jdk8u152-b16
 #hotspotTag=jdk8u172-b11
-hotspotTag=jdk8u181-b13
+#hotspotTag=jdk8u181-b13
+#hotspotTag=jdk8u201-b09
+hotspotTag=jdk8u202-b08
diff --git a/hotspot/.hg/patches/dmh-field-accessors-java8u201.patch b/hotspot/.hg/patches/dmh-field-accessors-java8u201.patch
new file mode 100644
index 00000000..ccd9a5b1
--- /dev/null
+++ b/hotspot/.hg/patches/dmh-field-accessors-java8u201.patch
@@ -0,0 +1,164 @@
+# HG changeset patch
+# User jklos
+# Date 1547858019 -3600
+#      Sat Jan 19 01:33:39 2019 +0100
+# Node ID 5ae0a29dd9ec239bbe6869f284bdad5f1a0e180c
+# Parent  3f33ee07f37817b4f687797700aa471edbec1da5
+diff -r 3f33ee07f378 -r 5ae0a29dd9ec src/share/vm/classfile/javaClasses.cpp
+--- a/src/share/vm/classfile/javaClasses.cpp	Sat Jan 19 01:28:17 2019 +0100
++++ b/src/share/vm/classfile/javaClasses.cpp	Sat Jan 19 01:33:39 2019 +0100
+@@ -2726,6 +2726,50 @@
+   }
+ }
+ 
++// Support for java_lang_invoke_DirectMethodHandle$StaticAccessor
++
++int java_lang_invoke_DirectMethodHandle_StaticAccessor::_static_offset_offset;
++
++long java_lang_invoke_DirectMethodHandle_StaticAccessor::static_offset(oop dmh) {
++  assert(_static_offset_offset != 0, "");
++  return dmh->long_field(_static_offset_offset);
++}
++
++void java_lang_invoke_DirectMethodHandle_StaticAccessor::set_static_offset(oop dmh, long static_offset) {
++  assert(_static_offset_offset != 0, "");
++  dmh->long_field_put(_static_offset_offset, static_offset);
++}
++
++
++void java_lang_invoke_DirectMethodHandle_StaticAccessor::compute_offsets() {
++  Klass* klass_oop = SystemDictionary::DirectMethodHandle_StaticAccessor_klass();
++  if (klass_oop != NULL && EnableInvokeDynamic) {
++    compute_offset(_static_offset_offset, klass_oop, vmSymbols::static_offset_name(), vmSymbols::long_signature());
++  }
++}
++
++// Support for java_lang_invoke_DirectMethodHandle$Accessor
++
++int java_lang_invoke_DirectMethodHandle_Accessor::_field_offset_offset;
++
++int java_lang_invoke_DirectMethodHandle_Accessor::field_offset(oop dmh) {
++  assert(_field_offset_offset != 0, "");
++  return dmh->int_field(_field_offset_offset);
++}
++
++void java_lang_invoke_DirectMethodHandle_Accessor::set_field_offset(oop dmh, int field_offset) {
++  assert(_field_offset_offset != 0, "");
++  dmh->int_field_put(_field_offset_offset, field_offset);
++}
++
++
++void java_lang_invoke_DirectMethodHandle_Accessor::compute_offsets() {
++  Klass* klass_oop = SystemDictionary::DirectMethodHandle_Accessor_klass();
++  if (klass_oop != NULL && EnableInvokeDynamic) {
++    compute_offset(_field_offset_offset, klass_oop, vmSymbols::field_offset_name(), vmSymbols::int_signature());
++  }
++}
++
+ // Support for java_lang_invoke_MethodHandle
+ 
+ int java_lang_invoke_MethodHandle::_type_offset;
+@@ -3386,6 +3430,9 @@
+     java_lang_invoke_LambdaForm::compute_offsets();
+     java_lang_invoke_MethodType::compute_offsets();
+     java_lang_invoke_CallSite::compute_offsets();
++
++    java_lang_invoke_DirectMethodHandle_StaticAccessor::compute_offsets();
++    java_lang_invoke_DirectMethodHandle_Accessor::compute_offsets();
+   }
+   java_security_AccessControlContext::compute_offsets();
+   // Initialize reflection classes. The layouts of these classes
+diff -r 3f33ee07f378 -r 5ae0a29dd9ec src/share/vm/classfile/javaClasses.hpp
+--- a/src/share/vm/classfile/javaClasses.hpp	Sat Jan 19 01:28:17 2019 +0100
++++ b/src/share/vm/classfile/javaClasses.hpp	Sat Jan 19 01:33:39 2019 +0100
+@@ -1042,6 +1042,55 @@
+   static int member_offset_in_bytes()           { return _member_offset; }
+ };
+ 
++// Interface to java.lang.invoke.DirectMethodHandle$StaticAccessor objects
++
++class java_lang_invoke_DirectMethodHandle_StaticAccessor: AllStatic {
++  friend class JavaClasses;
++
++ private:
++  static int _static_offset_offset;               // offset to static field
++
++  static void compute_offsets();
++
++ public:
++  // Accessors
++  static long      static_offset(oop dmh);
++  static void  set_static_offset(oop dmh, long value);
++
++  // Testers
++  static bool is_subclass(Klass* klass) {
++    return klass->is_subclass_of(SystemDictionary::DirectMethodHandle_StaticAccessor_klass());
++  }
++  static bool is_instance(oop obj) {
++    return obj != NULL && is_subclass(obj->klass());
++  }
++};
++
++// Interface to java.lang.invoke.DirectMethodHandle$Accessor objects
++
++class java_lang_invoke_DirectMethodHandle_Accessor: AllStatic {
++  friend class JavaClasses;
++
++ private:
++  static int _field_offset_offset;               // offset to field
++
++  static void compute_offsets();
++
++ public:
++  // Accessors
++  static int      field_offset(oop dmh);
++  static void set_field_offset(oop dmh, int value);
++
++  // Testers
++  static bool is_subclass(Klass* klass) {
++    return klass->is_subclass_of(SystemDictionary::DirectMethodHandle_Accessor_klass());
++  }
++  static bool is_instance(oop obj) {
++    return obj != NULL && is_subclass(obj->klass());
++  }
++};
++
++
+ // Interface to java.lang.invoke.LambdaForm objects
+ // (These are a private interface for managing adapter code generation.)
+ 
+diff -r 3f33ee07f378 -r 5ae0a29dd9ec src/share/vm/classfile/systemDictionary.hpp
+--- a/src/share/vm/classfile/systemDictionary.hpp	Sat Jan 19 01:28:17 2019 +0100
++++ b/src/share/vm/classfile/systemDictionary.hpp	Sat Jan 19 01:33:39 2019 +0100
+@@ -154,6 +154,8 @@
+                                                                                                                          \
+   /* support for dynamic typing; it's OK if these are NULL in earlier JDKs */                                            \
+   do_klass(DirectMethodHandle_klass,                    java_lang_invoke_DirectMethodHandle,       Opt                 ) \
++  do_klass(DirectMethodHandle_StaticAccessor_klass,     java_lang_invoke_DirectMethodHandle_StaticAccessor, Opt        ) \
++  do_klass(DirectMethodHandle_Accessor_klass,           java_lang_invoke_DirectMethodHandle_Accessor, Opt              ) \
+   do_klass(MethodHandle_klass,                          java_lang_invoke_MethodHandle,             Pre_JSR292          ) \
+   do_klass(MemberName_klass,                            java_lang_invoke_MemberName,               Pre_JSR292          ) \
+   do_klass(MethodHandleNatives_klass,                   java_lang_invoke_MethodHandleNatives,      Pre_JSR292          ) \
+diff -r 3f33ee07f378 -r 5ae0a29dd9ec src/share/vm/classfile/vmSymbols.hpp
+--- a/src/share/vm/classfile/vmSymbols.hpp	Sat Jan 19 01:28:17 2019 +0100
++++ b/src/share/vm/classfile/vmSymbols.hpp	Sat Jan 19 01:33:39 2019 +0100
+@@ -269,6 +269,8 @@
+   template(java_lang_invoke_CallSite,                 "java/lang/invoke/CallSite")                \
+   template(java_lang_invoke_ConstantCallSite,         "java/lang/invoke/ConstantCallSite")        \
+   template(java_lang_invoke_DirectMethodHandle,       "java/lang/invoke/DirectMethodHandle")      \
++  template(java_lang_invoke_DirectMethodHandle_StaticAccessor, "java/lang/invoke/DirectMethodHandle$StaticAccessor") \
++  template(java_lang_invoke_DirectMethodHandle_Accessor, "java/lang/invoke/DirectMethodHandle$Accessor") \
+   template(java_lang_invoke_MutableCallSite,          "java/lang/invoke/MutableCallSite")         \
+   template(java_lang_invoke_VolatileCallSite,         "java/lang/invoke/VolatileCallSite")        \
+   template(java_lang_invoke_MethodHandle,             "java/lang/invoke/MethodHandle")            \
+@@ -418,6 +420,10 @@
+   template(getProtectionDomain_name,                  "getProtectionDomain")                      \
+   template(getProtectionDomain_signature,             "(Ljava/security/CodeSource;)Ljava/security/ProtectionDomain;") \
+   template(url_code_signer_array_void_signature,      "(Ljava/net/URL;[Ljava/security/CodeSigner;)V") \
++  template(static_offset_name,                        "staticOffset")                             \
++  template(static_base_name,                          "staticBase")                               \
++  template(field_offset_name,                         "fieldOffset")                              \
++  template(field_type_name,                           "fieldType")                                \
+   template(resolved_references_name,                  "<resolved_references>")                    \
+   template(referencequeue_null_name,                  "NULL")                                     \
+   template(referencequeue_enqueued_name,              "ENQUEUED")                                 \
diff --git a/hotspot/.hg/patches/light-jdk8u201-b09.patch b/hotspot/.hg/patches/light-jdk8u201-b09.patch
new file mode 100644
index 00000000..a6e1ffcf
--- /dev/null
+++ b/hotspot/.hg/patches/light-jdk8u201-b09.patch
@@ -0,0 +1,3758 @@
+# HG changeset patch
+# User jklos
+# Date 1547865560 -3600
+#      Sat Jan 19 03:39:20 2019 +0100
+# Node ID 02a2c97b56996343813a96242a0de99c0a3a1121
+# Parent  da0f21b5d65d25f1bd7adfbf356ea4db11e6f3e3
+# Parent  7364d1b68594d50352a4abeb709060a2a34f2b85
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/ci/ciObjectFactory.cpp
+--- a/src/share/vm/ci/ciObjectFactory.cpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/ci/ciObjectFactory.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -800,3 +800,27 @@
+              _unloaded_instances->length(),
+              _unloaded_klasses->length());
+ }
++
++int ciObjectFactory::compare_cimetadata(ciMetadata** a, ciMetadata** b) {
++  Metadata* am = (*a)->constant_encoding();
++  Metadata* bm = (*b)->constant_encoding();
++  return ((am > bm) ? 1 : ((am == bm) ? 0 : -1));
++}
++
++// (DCEVM) Resoring the ciObject arrays after class redefinition
++void ciObjectFactory::resort_shared_ci_metadata() {
++  if (_shared_ci_metadata == NULL) return;
++  _shared_ci_metadata->sort(ciObjectFactory::compare_cimetadata);
++
++#ifdef ASSERT
++  if (CIObjectFactoryVerify) {
++    Metadata* last = NULL;
++    for (int j = 0; j< _shared_ci_metadata->length(); j++) {
++      Metadata* o = _shared_ci_metadata->at(j)->constant_encoding();
++      assert(last < o, "out of order");
++      last = o;
++    }
++  }
++#endif // ASSERT
++}
++
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/ci/ciObjectFactory.hpp
+--- a/src/share/vm/ci/ciObjectFactory.hpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/ci/ciObjectFactory.hpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -92,6 +92,7 @@
+ 
+   ciInstance* get_unloaded_instance(ciInstanceKlass* klass);
+ 
++  static int compare_cimetadata(ciMetadata** a, ciMetadata** b);
+ public:
+   static bool is_initialized() { return _initialized; }
+ 
+@@ -147,6 +148,8 @@
+ 
+   void print_contents();
+   void print();
++
++  static void resort_shared_ci_metadata();
+ };
+ 
+ #endif // SHARE_VM_CI_CIOBJECTFACTORY_HPP
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/classfile/classFileParser.cpp
+--- a/src/share/vm/classfile/classFileParser.cpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/classfile/classFileParser.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -767,6 +767,7 @@
+ Array<Klass*>* ClassFileParser::parse_interfaces(int length,
+                                                  Handle protection_domain,
+                                                  Symbol* class_name,
++                                                 bool pick_newest,
+                                                  bool* has_default_methods,
+                                                  TRAPS) {
+   if (length == 0) {
+@@ -785,7 +786,11 @@
+         "Interface name has bad constant pool index %u in class file %s",
+         interface_index, CHECK_NULL);
+       if (_cp->tag_at(interface_index).is_klass()) {
+-        interf = KlassHandle(THREAD, _cp->resolved_klass_at(interface_index));
++        Klass* resolved_klass = _cp->resolved_klass_at(interface_index);
++        if (pick_newest) {
++          resolved_klass = resolved_klass->newest_version();
++        }
++        interf = KlassHandle(THREAD, resolved_klass);
+       } else {
+         Symbol*  unresolved_klass  = _cp->klass_name_at(interface_index);
+ 
+@@ -799,6 +804,9 @@
+         Klass* k = SystemDictionary::resolve_super_or_fail(class_name,
+                       unresolved_klass, class_loader, protection_domain,
+                       false, CHECK_NULL);
++        if (pick_newest) {
++          k = k->newest_version();
++        }
+         interf = KlassHandle(THREAD, k);
+       }
+ 
+@@ -3156,6 +3164,7 @@
+ }
+ 
+ instanceKlassHandle ClassFileParser::parse_super_class(int super_class_index,
++                                                       bool pick_newest,
+                                                        TRAPS) {
+   instanceKlassHandle super_klass;
+   if (super_class_index == 0) {
+@@ -3172,7 +3181,11 @@
+     // 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));
++      Klass* resolved_klass = _cp->resolved_klass_at(super_class_index);
++      if (pick_newest) {
++        resolved_klass = resolved_klass->newest_version();
++      }
++      super_klass = instanceKlassHandle(THREAD, resolved_klass);
+       if (_need_verify)
+         is_array = super_klass->oop_is_array();
+     } else if (_need_verify) {
+@@ -3721,8 +3734,10 @@
+ instanceKlassHandle ClassFileParser::parseClassFile(Symbol* name,
+                                                     ClassLoaderData* loader_data,
+                                                     Handle protection_domain,
++                                                    KlassHandle old_klass,
+                                                     KlassHandle host_klass,
+                                                     GrowableArray<Handle>* cp_patches,
++                                                    GrowableArray<Symbol*>* parsed_super_symbols,
+                                                     TempNewSymbol& parsed_name,
+                                                     bool verify,
+                                                     TRAPS) {
+@@ -3736,6 +3751,7 @@
+   Handle class_loader(THREAD, loader_data->class_loader());
+   bool has_default_methods = false;
+   bool declares_default_methods = false;
++  bool pick_newest = !old_klass.is_null();
+   ResourceMark rm(THREAD);
+ 
+   ClassFileStream* cfs = stream();
+@@ -3752,7 +3768,7 @@
+ 
+   init_parsed_class_attributes(loader_data);
+ 
+-  if (JvmtiExport::should_post_class_file_load_hook()) {
++  if (parsed_super_symbols == NULL && JvmtiExport::should_post_class_file_load_hook()) {
+     // Get the cached class file bytes (if any) from the class that
+     // is being redefined or retransformed. We use jvmti_thread_state()
+     // instead of JvmtiThreadState::state_for(jt) so we don't allocate
+@@ -3913,6 +3929,26 @@
+                        CHECK_(nullHandle));
+   }
+ 
++  // (DCEVM) Do not parse full class file, only get super symbols and return.
++  if (parsed_super_symbols != NULL) {
++    u2 super_class_index = cfs->get_u2_fast();
++
++    if (super_class_index != 0) {
++      parsed_super_symbols->append(cp->klass_name_at(super_class_index));
++    }
++
++    // Interfaces
++    u2 itfs_len = cfs->get_u2_fast();
++    Array<Klass*>* local_interfaces =
++        parse_interfaces(itfs_len, protection_domain, _class_name, pick_newest, &has_default_methods, CHECK_NULL);
++
++    for (int i = 0; i < local_interfaces->length(); i++) {
++      Klass* o = local_interfaces->at(i);
++      parsed_super_symbols->append(o->name());
++    }
++    return NULL;
++  }
++
+   Klass* preserve_this_klass;   // for storing result across HandleMark
+ 
+   // release all handles when parsing is done
+@@ -3951,13 +3987,14 @@
+ 
+     u2 super_class_index = cfs->get_u2_fast();
+     instanceKlassHandle super_klass = parse_super_class(super_class_index,
++                                                        pick_newest,
+                                                         CHECK_NULL);
+ 
+     // Interfaces
+     u2 itfs_len = cfs->get_u2_fast();
+     Array<Klass*>* local_interfaces =
+       parse_interfaces(itfs_len, protection_domain, _class_name,
+-                       &has_default_methods, CHECK_(nullHandle));
++                       pick_newest, &has_default_methods, CHECK_(nullHandle));
+ 
+     u2 java_fields_count = 0;
+     // Fields (offsets are filled in later)
+@@ -4011,6 +4048,9 @@
+                                                          true,
+                                                          CHECK_(nullHandle));
+ 
++      if (pick_newest) {
++        k = k->newest_version();
++      }
+       KlassHandle kh (THREAD, k);
+       super_klass = instanceKlassHandle(THREAD, kh());
+     }
+@@ -4176,7 +4216,7 @@
+     fill_oop_maps(this_klass, info.nonstatic_oop_map_count, info.nonstatic_oop_offsets, info.nonstatic_oop_counts);
+ 
+     // Fill in has_finalizer, has_vanilla_constructor, and layout_helper
+-    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));
+@@ -4425,7 +4465,7 @@
+ }
+ 
+ 
+-void ClassFileParser::set_precomputed_flags(instanceKlassHandle k) {
++void ClassFileParser::set_precomputed_flags(instanceKlassHandle k, KlassHandle old_klass) {
+   Klass* super = k->super();
+ 
+   // Check if this klass has an empty finalize method (i.e. one with return bytecode only),
+@@ -4433,7 +4473,9 @@
+   if (!_has_empty_finalizer) {
+     if (_has_finalizer ||
+         (super != NULL && super->has_finalizer())) {
+-      k->set_has_finalizer();
++      if (old_klass.is_null() || old_klass->has_finalizer()) {
++        k->set_has_finalizer();
++      }
+     }
+   }
+ 
+@@ -4455,7 +4497,7 @@
+ 
+   // 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()->newest_version())) {
+       k->set_is_cloneable();
+     }
+   }
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/classfile/classFileParser.hpp
+--- a/src/share/vm/classfile/classFileParser.hpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/classfile/classFileParser.hpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -219,11 +219,12 @@
+   Array<Klass*>* parse_interfaces(int length,
+                                   Handle protection_domain,
+                                   Symbol* class_name,
++                                  bool pick_newest,
+                                   bool* has_default_methods,
+                                   TRAPS);
+   void record_defined_class_dependencies(instanceKlassHandle defined_klass, TRAPS);
+ 
+-  instanceKlassHandle parse_super_class(int super_class_index, TRAPS);
++  instanceKlassHandle parse_super_class(int super_class_index, bool pick_newest, TRAPS);
+   // Field parsing
+   void parse_field_attributes(u2 attributes_count,
+                               bool is_static, u2 signature_index,
+@@ -305,7 +306,7 @@
+                      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);
+   Array<Klass*>* compute_transitive_interfaces(instanceKlassHandle super,
+                                                Array<Klass*>* local_ifs, TRAPS);
+ 
+@@ -471,17 +472,20 @@
+   instanceKlassHandle parseClassFile(Symbol* name,
+                                      ClassLoaderData* loader_data,
+                                      Handle protection_domain,
++                                     KlassHandle old_klass,
+                                      TempNewSymbol& parsed_name,
+                                      bool verify,
+                                      TRAPS) {
+     KlassHandle no_host_klass;
+-    return parseClassFile(name, loader_data, protection_domain, no_host_klass, NULL, parsed_name, verify, THREAD);
++    return parseClassFile(name, loader_data, protection_domain, old_klass, no_host_klass, NULL, NULL, parsed_name, verify, THREAD);
+   }
+   instanceKlassHandle parseClassFile(Symbol* name,
+                                      ClassLoaderData* loader_data,
+                                      Handle protection_domain,
++                                     KlassHandle old_klass,
+                                      KlassHandle host_klass,
+                                      GrowableArray<Handle>* cp_patches,
++                                     GrowableArray<Symbol*>* parsed_super_symbols,
+                                      TempNewSymbol& parsed_name,
+                                      bool verify,
+                                      TRAPS);
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/classfile/classLoader.cpp
+--- a/src/share/vm/classfile/classLoader.cpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/classfile/classLoader.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -1124,6 +1124,7 @@
+     instanceKlassHandle result = parser.parseClassFile(h_name,
+                                                        loader_data,
+                                                        protection_domain,
++                                                       KlassHandle(),
+                                                        parsed_name,
+                                                        context.should_verify(classpath_index),
+                                                        THREAD);
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/classfile/dictionary.cpp
+--- a/src/share/vm/classfile/dictionary.cpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/classfile/dictionary.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -156,7 +156,7 @@
+       InstanceKlass* ik = InstanceKlass::cast(e);
+ 
+       // Non-unloadable classes were handled in always_strong_oops_do
+-      if (!is_strongly_reachable(loader_data, e)) {
++      if (!ik->is_redefining() && !is_strongly_reachable(loader_data, e)) {
+         // Entry was not visited in phase1 (negated test from phase1)
+         assert(!loader_data->is_the_null_class_loader_data(), "unloading entry with null class loader");
+ 
+@@ -357,6 +357,32 @@
+   add_entry(index, entry);
+ }
+ 
++// (DCEVM) Updates the klass entry to point to the new Klass*. Necessary only for class redefinition.
++bool Dictionary::update_klass(int index, unsigned int hash, Symbol* name, ClassLoaderData* loader_data, 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()->is_redefining()) {
++        entry->set_literal(entry->klass()->old_version());
++      }
++    }
++  }
++}
+ 
+ // This routine does not lock the system dictionary.
+ //
+@@ -387,7 +413,7 @@
+                           ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
+   DictionaryEntry* entry = get_entry(index, hash, name, loader_data);
+   if (entry != NULL && entry->is_valid_protection_domain(protection_domain)) {
+-    return entry->klass();
++    return intercept_for_version(entry->klass());
+   } else {
+     return NULL;
+   }
+@@ -400,7 +426,7 @@
+   assert (index == index_for(name, loader_data), "incorrect index?");
+ 
+   DictionaryEntry* entry = get_entry(index, hash, name, loader_data);
+-  return (entry != NULL) ? entry->klass() : (Klass*)NULL;
++  return intercept_for_version((entry != NULL) ? entry->klass() : (Klass*)NULL);
+ }
+ 
+ 
+@@ -412,7 +438,7 @@
+   assert (index == index_for(name, NULL), "incorrect index?");
+ 
+   DictionaryEntry* entry = get_entry(index, hash, name, NULL);
+-  return (entry != NULL) ? entry->klass() : (Klass*)NULL;
++  return intercept_for_version((entry != NULL) ? entry->klass() : (Klass*)NULL);
+ }
+ 
+ 
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/classfile/dictionary.hpp
+--- a/src/share/vm/classfile/dictionary.hpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/classfile/dictionary.hpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -81,6 +81,10 @@
+ 
+   void add_klass(Symbol* class_name, ClassLoaderData* loader_data,KlassHandle obj);
+ 
++  bool update_klass(int index, unsigned int hash, Symbol* name, ClassLoaderData* loader_data, KlassHandle k, KlassHandle old_class);
++
++  void rollback_redefinition();
++
+   Klass* find_class(int index, unsigned int hash,
+                       Symbol* name, ClassLoaderData* loader_data);
+ 
+@@ -112,6 +116,11 @@
+     return (loader_data->is_the_null_class_loader_data() || !ClassUnloading);
+   }
+ 
++  // (DCEVM) During enhanced class redefinition we want old version if new is being redefined
++  static Klass* intercept_for_version(Klass* k) {
++    return (k != NULL && k->is_redefining()) ? k->old_version() : k;
++  }
++ 
+   // Unload (that is, break root links to) all unmarked classes and loaders.
+   void do_unloading();
+ 
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/classfile/javaClasses.cpp
+--- a/src/share/vm/classfile/javaClasses.cpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/classfile/javaClasses.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -1709,6 +1709,8 @@
+         skip_throwableInit_check = true;
+       }
+     }
++    // (DCEVM): Line numbers from newest version must be used for EMCP-swapped methods
++    method = method->newest_version();
+     if (method->is_hidden()) {
+       if (skip_hidden)  continue;
+     }
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/classfile/loaderConstraints.cpp
+--- a/src/share/vm/classfile/loaderConstraints.cpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/classfile/loaderConstraints.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -98,6 +98,19 @@
+   return pp;
+ }
+ 
++void LoaderConstraintTable::update_after_redefinition() {
++  for (int index = 0; index < table_size(); index++) {
++    LoaderConstraintEntry** p = bucket_addr(index);
++    while(*p) {
++      LoaderConstraintEntry* probe = *p;
++      if (probe->klass() != NULL) {
++        // We swap the class with the newest version with an assumption that the hash will be the same
++        probe->set_klass(probe->klass()->newest_version());
++      }
++      p = probe->next_addr();
++    }
++  }
++}
+ 
+ void LoaderConstraintTable::purge_loader_constraints() {
+   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
+@@ -446,7 +459,7 @@
+         if (k != NULL) {
+           // We found the class in the system dictionary, so we should
+           // make sure that the Klass* matches what we already have.
+-          guarantee(k == probe->klass(), "klass should be in dictionary");
++          guarantee(k == probe->klass()->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 -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/classfile/loaderConstraints.hpp
+--- a/src/share/vm/classfile/loaderConstraints.hpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/classfile/loaderConstraints.hpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -64,6 +64,9 @@
+   // Enhanced Class Redefinition support
+   void classes_do(KlassClosure* f);
+ 
++  // (DCEVM) update all klasses with newest version
++  void update_after_redefinition();
++
+   // Check class loader constraints
+   bool add_entry(Symbol* name, Klass* klass1, Handle loader1,
+                                     Klass* klass2, Handle loader2);
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/classfile/systemDictionary.cpp
+--- a/src/share/vm/classfile/systemDictionary.cpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/classfile/systemDictionary.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -182,6 +182,7 @@
+     // can return a null klass
+     klass = handle_resolution_exception(class_name, class_loader, protection_domain, throw_error, k_h, THREAD);
+   }
++  assert(klass == NULL || klass->is_newest_version() || klass->newest_version()->is_redefining(), "must be");
+   return klass;
+ }
+ 
+@@ -224,7 +225,7 @@
+ // Forwards to resolve_instance_class_or_null
+ 
+ Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
+-  assert(!THREAD->is_Compiler_thread(),
++  assert(!THREAD->is_Compiler_thread() || JvmtiThreadState::state_for(JavaThread::current())->get_class_being_redefined() != NULL,
+          err_msg("can not load classes with compiler thread: class=%s, classloader=%s",
+                  class_name->as_C_string(),
+                  class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string()));
+@@ -1006,8 +1007,10 @@
+   instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
+                                                              loader_data,
+                                                              protection_domain,
++                                                             KlassHandle(),
+                                                              host_klass,
+                                                              cp_patches,
++                                                             NULL,
+                                                              parsed_name,
+                                                              true,
+                                                              THREAD);
+@@ -1061,6 +1064,7 @@
+                                              Handle protection_domain,
+                                              ClassFileStream* st,
+                                              bool verify,
++                                             KlassHandle old_class,
+                                              TRAPS) {
+ 
+   // Classloaders that support parallelism, e.g. bootstrap classloader,
+@@ -1088,9 +1092,15 @@
+   instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
+                                                              loader_data,
+                                                              protection_domain,
++                                                             old_class,
+                                                              parsed_name,
+                                                              verify,
+                                                              THREAD);
++  // (DCEVM) During enhanced class redefinition, mark loaded class as being redefined
++  if (!old_class.is_null() && !k.is_null()) {
++    k->set_redefining(true);
++    k->set_old_version(old_class());
++  }
+ 
+   const char* pkg = "java/";
+   size_t pkglen = strlen(pkg);
+@@ -1128,10 +1138,11 @@
+     // 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)) {
++    // (DCEVM) 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);
+     }
+   }
+ 
+@@ -1145,7 +1156,7 @@
+       MutexLocker mu(SystemDictionary_lock, THREAD);
+ 
+       Klass* check = find_class(parsed_name, loader_data);
+-      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");
+ 
+       Klass* check2 = find_class(h_name, defining_loader_data);
+       assert(check == check2, "name inconsistancy in SystemDictionary");
+@@ -1385,7 +1396,11 @@
+   }
+ }
+ 
+-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) {
+ 
+   ClassLoaderData* loader_data = k->class_loader_data();
+   Handle class_loader_h(THREAD, loader_data->class_loader());
+@@ -1415,7 +1430,17 @@
+   Symbol*  name_h = k->name();
+   unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
+   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 Klass* 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, loader_data, 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);
++
++  // FIXME: (DCEVM) clean this...
++  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
+@@ -1448,8 +1473,9 @@
+   }
+   k->eager_initialize(THREAD);
+ 
++  // (DCEVM) 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());
+ 
+@@ -1523,7 +1549,7 @@
+     }
+   }
+ 
+-  define_instance_class(k, THREAD);
++  define_instance_class(k, KlassHandle(), THREAD);
+ 
+   Handle linkage_exception = Handle(); // null handle
+ 
+@@ -1632,6 +1658,19 @@
+   return dictionary()->try_get_next_class();
+ }
+ 
++// (DCEVM) Remove from hierarchy - Undo add_to_hierarchy.
++void SystemDictionary::remove_from_hierarchy(instanceKlassHandle k) {
++  assert(k.not_null(), "just checking");
++
++  // remove receiver from sibling list
++  k->remove_from_sibling_list();
++  // TODO (DCEVM): Remove from interfaces.
++}
++
++// (DCEVM) Update constraints
++void SystemDictionary::update_constraints_after_redefinition() {
++  constraints()->update_after_redefinition();
++}
+ 
+ // ----------------------------------------------------------------------------
+ // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
+@@ -2011,7 +2050,7 @@
+       // also holds array classes
+ 
+       assert(check->oop_is_instance(), "noninstance in systemdictionary");
+-      if ((defining == true) || (k() != check)) {
++      if ((defining == true) && ((k() != check) && k->old_version() != check)) {
+         linkage_error = "loader (instance of  %s): attempted  duplicate class "
+           "definition for name: \"%s\"";
+       } else {
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/classfile/systemDictionary.hpp
+--- a/src/share/vm/classfile/systemDictionary.hpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/classfile/systemDictionary.hpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -285,7 +285,7 @@
+   // Resolve from stream (called by jni_DefineClass and JVM_DefineClass)
+   static Klass* 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 Klass* find(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS);
+@@ -359,6 +359,12 @@
+   // System loader lock
+   static oop system_loader_lock()           { return _system_loader_lock_obj; }
+ 
++  // (DCEVM) Remove link to hierarchy
++  static void remove_from_hierarchy(instanceKlassHandle k);
++
++  // (DCEVM) Update constraints
++  static void update_constraints_after_redefinition();
++
+ protected:
+   // Extended Redefine classes support (tbi)
+   static void preloaded_classes_do(KlassClosure* f);
+@@ -425,6 +431,9 @@
+     initialize_wk_klasses_until((WKID) limit, start_id, THREAD);
+   }
+ 
++  // (DCEVM) rollback class redefinition
++  static void rollback_redefinition();
++
+ public:
+   #define WK_KLASS_DECLARE(name, symbol, option) \
+     static Klass* name() { return check_klass_##option(_well_known_klasses[WK_KLASS_ENUM_NAME(name)]); } \
+@@ -630,7 +639,7 @@
+   // 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);
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/classfile/verifier.cpp
+--- a/src/share/vm/classfile/verifier.cpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/classfile/verifier.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -189,7 +189,7 @@
+   Symbol* name = klass->name();
+   Klass* refl_magic_klass = SystemDictionary::reflect_MagicAccessorImpl_klass();
+ 
+-  bool is_reflect = refl_magic_klass != NULL && klass->is_subtype_of(refl_magic_klass);
++  bool is_reflect = refl_magic_klass != NULL && (klass->is_subtype_of(refl_magic_klass) || klass->is_subtype_of(refl_magic_klass->newest_version()));
+ 
+   return (should_verify_for(klass->class_loader(), should_verify_class) &&
+     // return if the class is a bootstrapping class
+@@ -523,7 +523,7 @@
+ 
+ ClassVerifier::ClassVerifier(
+     instanceKlassHandle klass, TRAPS)
+-    : _thread(THREAD), _exception_type(NULL), _message(NULL), _klass(klass) {
++    : _thread(THREAD), _exception_type(NULL), _message(NULL), _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);
+@@ -553,7 +553,7 @@
+       _klass->external_name());
+   }
+ 
+-  Array<Method*>* methods = _klass->methods();
++  Array<Method*>* methods = _klass_to_verify->methods();
+   int num_methods = methods->length();
+ 
+   for (int index = 0; index < num_methods; index++) {
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/classfile/verifier.hpp
+--- a/src/share/vm/classfile/verifier.hpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/classfile/verifier.hpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -344,6 +344,7 @@
+ 
+   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 -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/interpreter/linkResolver.cpp
+--- a/src/share/vm/interpreter/linkResolver.cpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/interpreter/linkResolver.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -215,8 +215,8 @@
+ // Klass resolution
+ 
+ void LinkResolver::check_klass_accessability(KlassHandle ref_klass, KlassHandle sel_klass, TRAPS) {
+-  if (!Reflection::verify_class_access(ref_klass(),
+-                                       sel_klass(),
++  if (!Reflection::verify_class_access(ref_klass()->newest_version(),
++                                       sel_klass()->newest_version(),
+                                        true)) {
+     ResourceMark rm(THREAD);
+     Exceptions::fthrow(
+@@ -464,7 +464,7 @@
+   // 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()->newest_version() == SystemDictionary::Object_klass()->newest_version() &&
+       resolved_klass->oop_is_array()) {
+     // We need to change "protected" to "public".
+     assert(flags.is_protected(), "clone not protected?");
+@@ -794,7 +794,7 @@
+     }
+ 
+     // Final fields can only be accessed from its own class.
+-    if (is_put && fd.access_flags().is_final() && sel_klass() != current_klass()) {
++    if (is_put && fd.access_flags().is_final() && sel_klass() != current_klass() && sel_klass() != current_klass()->active_version()) {
+       THROW(vmSymbols::java_lang_IllegalAccessError());
+     }
+ 
+@@ -1215,6 +1215,8 @@
+       // 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();
++      // (DCEVM) Check that the receiver is a subtype of the holder of the resolved method.
++      assert(inst->is_subtype_of(resolved_method->method_holder()), "receiver and resolved method holder are inconsistent");
+       selected_method = methodHandle(THREAD, inst->method_at_vtable(vtable_index));
+     }
+   }
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/memory/universe.cpp
+--- a/src/share/vm/memory/universe.cpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/memory/universe.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -169,6 +169,43 @@
+   f(doubleArrayKlassObj());
+ }
+ 
++// (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;
++
++  Universe::oops_do(oopClosure);
++//  ReferenceProcessor::oops_do(oopClosure); (tw) check why no longer there
++  JNIHandles::oops_do(oopClosure);   // Global (strong) JNI handles
++  Threads::oops_do(oopClosure, NULL, NULL);
++  ObjectSynchronizer::oops_do(oopClosure);
++  FlatProfiler::oops_do(oopClosure);
++  JvmtiExport::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);
++
++  CodeBlobToOopClosure blobClosure(oopClosure, CodeBlobToOopClosure::FixRelocations);
++  CodeCache::blobs_do(&blobClosure);
++  StringTable::oops_do(oopClosure);
++  
++  // (DCEVM) TODO: Check if this is correct?
++  //CodeCache::scavenge_root_nmethods_oops_do(oopClosure);
++  //Management::oops_do(oopClosure);
++  //ref_processor()->weak_oops_do(&oopClosure);
++  //PSScavenge::reference_processor()->weak_oops_do(&oopClosure);
++
++  // SO_AllClasses
++  SystemDictionary::oops_do(oopClosure);
++}
++
+ void Universe::oops_do(OopClosure* f, bool do_all) {
+ 
+   f->do_oop((oop*) &_int_mirror);
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/memory/universe.hpp
+--- a/src/share/vm/memory/universe.hpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/memory/universe.hpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -416,6 +416,7 @@
+   static void run_finalizers_on_exit();
+ 
+   // 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".
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/oops/cpCache.cpp
+--- a/src/share/vm/oops/cpCache.cpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/oops/cpCache.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -357,7 +357,8 @@
+   if (has_appendix) {
+     const int appendix_index = f2_as_index() + _indy_resolved_references_appendix_offset;
+     assert(appendix_index >= 0 && appendix_index < resolved_references->length(), "oob");
+-    assert(resolved_references->obj_at(appendix_index) == NULL, "init just once");
++    // FIXME (DCEVM) relaxing for now...
++    //assert(resolved_references->obj_at(appendix_index) == NULL, "init just once");
+     resolved_references->obj_at_put(appendix_index, appendix());
+   }
+ 
+@@ -365,7 +366,8 @@
+   if (has_method_type) {
+     const int method_type_index = f2_as_index() + _indy_resolved_references_method_type_offset;
+     assert(method_type_index >= 0 && method_type_index < resolved_references->length(), "oob");
+-    assert(resolved_references->obj_at(method_type_index) == NULL, "init just once");
++    // FIXME (DCEVM) relaxing for now...
++    //assert(resolved_references->obj_at(method_type_index) == NULL, "init just once");
+     resolved_references->obj_at_put(method_type_index, method_type());
+   }
+ 
+@@ -532,6 +534,22 @@
+   // the method is in the interesting class so the entry is interesting
+   return m;
+ }
++
++// Enhanced RedefineClasses() API support (DCEVM):
++// Clear cached entry, let it be re-resolved
++void ConstantPoolCacheEntry::clear_entry() {
++  _indices = constant_pool_index();
++  _f1 = NULL;
++  if (!is_resolved_reference()) {
++    _f2 = 0;
++  }
++  // FIXME: (DCEVM) we want to clear flags, but parameter size is actually used
++  // after we return from the method, before entry is re-initialized. So let's
++  // keep parameter size the same.
++  // For example, it's used in TemplateInterpreterGenerator::generate_return_entry_for
++  // Also, we need to keep flag marking entry as one containing resolved_reference
++  _flags &= parameter_size_mask | (1 << is_resolved_ref_shift);
++}
+ #endif // INCLUDE_JVMTI
+ 
+ void ConstantPoolCacheEntry::print(outputStream* st, int index) const {
+@@ -645,6 +663,14 @@
+     }
+   }
+ }
++
++// Enhanced RedefineClasses() API support (DCEVM):
++// Clear all entries
++void ConstantPoolCache::clear_entries() {
++  for (int i = 0; i < length(); i++) {
++    entry_at(i)->clear_entry();
++  }
++}
+ #endif // INCLUDE_JVMTI
+ 
+ 
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/oops/cpCache.hpp
+--- a/src/share/vm/oops/cpCache.hpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/oops/cpCache.hpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -179,6 +179,8 @@
+     tos_state_bits             = 4,
+     tos_state_mask             = right_n_bits(tos_state_bits),
+     tos_state_shift            = BitsPerInt - tos_state_bits,  // see verify_tos_state_shift below
++    // (DCEVM) We need to remember entries which has resolved reference indices as we don't want to clean them
++    is_resolved_ref_shift      = 27,
+     // misc. option bits; can be any bit position in [16..27]
+     is_field_entry_shift       = 26,  // (F) is it a field or a method?
+     has_method_type_shift      = 25,  // (M) does the call site have a MethodType?
+@@ -211,6 +213,7 @@
+   void initialize_resolved_reference_index(int ref_index) {
+     assert(_f2 == 0, "set once");  // note: ref_index might be zero also
+     _f2 = ref_index;
++    _flags = 1 << is_resolved_ref_shift;
+   }
+ 
+   void set_field(                                // sets entry to resolved field state
+@@ -352,6 +355,7 @@
+   bool is_final() const                          { return (_flags & (1 << is_final_shift))          != 0; }
+   bool is_forced_virtual() const                 { return (_flags & (1 << is_forced_virtual_shift)) != 0; }
+   bool is_vfinal() const                         { return (_flags & (1 << is_vfinal_shift))         != 0; }
++  bool is_resolved_reference() const             { return (_flags & (1 << is_resolved_ref_shift))   != 0; }
+   bool has_appendix() const                      { return (!is_f1_null()) && (_flags & (1 << has_appendix_shift))      != 0; }
+   bool has_method_type() const                   { return (!is_f1_null()) && (_flags & (1 << has_method_type_shift))   != 0; }
+   bool is_method_entry() const                   { return (_flags & (1 << is_field_entry_shift))    == 0; }
+@@ -380,6 +384,10 @@
+          bool* trace_name_printed);
+   bool check_no_old_or_obsolete_entries();
+   Method* get_interesting_method_entry(Klass* k);
++
++  // Enhanced RedefineClasses() API support (DCEVM):
++  // Clear cached entry, let it be re-resolved
++  void clear_entry();
+ #endif // INCLUDE_JVMTI
+ 
+   // Debugging & Printing
+@@ -478,6 +486,10 @@
+   void adjust_method_entries(InstanceKlass* holder, bool* trace_name_printed);
+   bool check_no_old_or_obsolete_entries();
+   void dump_cache();
++
++  // Enhanced RedefineClasses() API support (DCEVM):
++  // Clear all entries
++  void clear_entries();
+ #endif // INCLUDE_JVMTI
+ 
+   // Deallocate - no fields to deallocate
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/oops/instanceKlass.cpp
+--- a/src/share/vm/oops/instanceKlass.cpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/oops/instanceKlass.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -749,7 +749,8 @@
+       }
+ #endif
+       this_oop->set_init_state(linked);
+-      if (JvmtiExport::should_post_class_prepare()) {
++      // (DCEVM) 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());
+@@ -846,7 +847,9 @@
+     // If we were to use wait() instead of waitInterruptibly() then
+     // we might end up throwing IE from link/symbol resolution sites
+     // that aren't expected to throw.  This would wreak havoc.  See 6320309.
+-    while(this_oop->is_being_initialized() && !this_oop->is_reentrant_initialization(self)) {
++    // (DCEVM) Wait also for the old class version to be fully initialized.
++    while((this_oop->is_being_initialized() && !this_oop->is_reentrant_initialization(self))
++       || (this_oop->old_version() != NULL && InstanceKlass::cast(this_oop->old_version())->is_being_initialized())) {
+         wait = true;
+       ol.waitUninterruptibly(CHECK);
+     }
+@@ -1097,6 +1100,18 @@
+   return false;
+ }
+ 
++bool InstanceKlass::implements_interface_any_version(Klass* k) const {
++  k = k->newest_version();
++  if (this->newest_version() == k) return true;
++  assert(k->is_interface(), "should be an interface class");
++  for (int i = 0; i < transitive_interfaces()->length(); i++) {
++    if (transitive_interfaces()->at(i)->newest_version() == k) {
++      return true;
++    }
++  }
++  return false;
++}
++
+ bool InstanceKlass::is_same_or_direct_interface(Klass *k) const {
+   // Verify direct super interface
+   if (this == k) return true;
+@@ -1364,6 +1379,18 @@
+   }
+ }
+ 
++void InstanceKlass::store_update_information(GrowableArray<int> &values) {
++  int *arr = NEW_C_HEAP_ARRAY(int, values.length(), mtClass);
++  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(), mtClass);
++  set_update_information(NULL);
++}
+ 
+ void InstanceKlass::do_local_static_fields(FieldClosure* cl) {
+   for (JavaFieldStream fs(this); !fs.done(); fs.next()) {
+@@ -2022,6 +2049,18 @@
+   _dependencies = new nmethodBucket(nm, _dependencies);
+ }
+ 
++bool InstanceKlass::update_jmethod_id(Method* 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 method id (may be NULL)
++    return true;
++  }
++  return false;
++}
+ 
+ //
+ // Decrement count of the nmethod in the dependency list and remove
+@@ -2055,6 +2094,13 @@
+     last = b;
+     b = b->next();
+   }
++
++  // (DCEVM) Hack as dependencies get wrong version of Klass*
++  if (this->old_version() != NULL) {
++    InstanceKlass::cast(this->old_version())->remove_dependent_nmethod(nm, true);
++    return;
++  }
++
+ #ifdef ASSERT
+   tty->print_cr("### %s can't find dependent nmethod:", this->external_name());
+   nm->print();
+@@ -3105,6 +3151,24 @@
+   assert(is_klass(), "must be klass");
+   Klass::print_on(st);
+ 
++  // (DCEVM) Output revision number and revision numbers of older / newer and oldest / newest version of this class.
++  if (AllowEnhancedClassRedefinition) {
++    st->print(BULLET"revision:          %d", revision_number());
++    if (new_version() != NULL) {
++      st->print(" (newer=%d)", new_version()->revision_number());
++    }
++    if (newest_version() != new_version() && newest_version() != this) {
++      st->print(" (newest=%d)", newest_version()->revision_number());
++    }
++    if (old_version() != NULL) {
++      st->print(" (old=%d)", old_version()->revision_number());
++    }
++    if (oldest_version() != old_version() && oldest_version() != this) {
++      st->print(" (oldest=%d)", oldest_version()->revision_number());
++    }
++    st->cr();
++  }
++
+   st->print(BULLET"instance size:     %d", size_helper());                        st->cr();
+   st->print(BULLET"klass size:        %d", size());                               st->cr();
+   st->print(BULLET"access:            "); access_flags().print_on(st);            st->cr();
+@@ -3437,7 +3501,7 @@
+     }
+ 
+     guarantee(sib->is_klass(), "should be klass");
+-    guarantee(sib->super() == super, "siblings should have same superklass");
++    guarantee(sib->super() == super || super->newest_version() == SystemDictionary::Object_klass(), "siblings should have same superklass");
+   }
+ 
+   // Verify implementor fields
+@@ -3602,6 +3666,7 @@
+ 
+ // Purge previous versions
+ void InstanceKlass::purge_previous_versions(InstanceKlass* ik) {
++  // FIXME: (DCEVM) Should we purge something?    
+   if (ik->previous_versions() != NULL) {
+     // This klass has previous versions so see what we can cleanup
+     // while it is safe to do so.
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/oops/instanceKlass.hpp
+--- a/src/share/vm/oops/instanceKlass.hpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/oops/instanceKlass.hpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -138,6 +138,7 @@
+   friend class VMStructs;
+   friend class ClassFileParser;
+   friend class CompileReplay;
++  friend class VM_EnhancedRedefineClasses;
+ 
+  protected:
+   // Constructor
+@@ -673,7 +674,7 @@
+   InstanceKlass* previous_versions() const { return _previous_versions; }
+ 
+   bool has_been_redefined() const {
+-    return (_misc_flags & _misc_has_been_redefined) != 0;
++    return (_misc_flags & _misc_has_been_redefined) != 0 && _old_version != NULL;
+   }
+   void set_has_been_redefined() {
+     _misc_flags |= _misc_has_been_redefined;
+@@ -769,6 +770,7 @@
+   static void get_jmethod_id_length_value(jmethodID* cache, size_t idnum,
+                 size_t *length_p, jmethodID* id_p);
+   jmethodID jmethod_id_or_null(Method* method);
++  bool update_jmethod_id(Method* method, jmethodID newMethodID);
+ 
+   // annotations support
+   Annotations* annotations() const          { return _annotations; }
+@@ -839,6 +841,7 @@
+   // subclass/subinterface checks
+   bool implements_interface(Klass* k) const;
+   bool is_same_or_direct_interface(Klass* k) const;
++  bool implements_interface_any_version(Klass* k) const;
+ 
+ #ifdef ASSERT
+   // check whether this class or one of its superclasses was redefined
+@@ -895,6 +898,10 @@
+   void do_nonstatic_fields(FieldClosure* cl); // including inherited fields
+   void do_local_static_fields(void f(fieldDescriptor*, Handle, TRAPS), Handle, TRAPS);
+ 
++  // (DCEVM) instance update information to be used in GC run
++  void store_update_information(GrowableArray<int> &values);
++  void clear_update_information();
++
+   void methods_do(void f(Method* method));
+   void array_klasses_do(void f(Klass* k));
+   void array_klasses_do(void f(Klass* k, TRAPS), TRAPS);
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/oops/klass.cpp
+--- a/src/share/vm/oops/klass.cpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/oops/klass.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -199,6 +199,13 @@
+   set_next_link(NULL);
+   TRACE_INIT_ID(this);
+ 
++  set_redefinition_flags(Klass::NoRedefinition);
++  set_redefining(false);
++  set_new_version(NULL);
++  set_old_version(NULL);
++  set_redefinition_index(-1);
++  set_revision_number(-1);
++
+   set_prototype_header(markOopDesc::prototype());
+   set_biased_lock_revocation_count(0);
+   set_last_biased_lock_bulk_revocation_time(0);
+@@ -405,6 +412,24 @@
+   debug_only(verify();)
+ }
+ 
++// (DCEVM)
++void Klass::remove_from_sibling_list() {
++  debug_only(verify();)
++  // remove ourselves to superklass' subklass list
++  InstanceKlass* super = superklass();
++  assert(super != NULL, "should have super");
++  if (super->subklass() == this) {
++    // first subklass
++    super->set_subklass(next_sibling());
++  } else {
++    Klass* sib = super->subklass();
++    while (sib->next_sibling() != this) {
++      sib = sib->next_sibling();
++    };
++    sib->set_next_sibling(next_sibling());
++  }
++}
++
+ bool Klass::is_loader_alive(BoolObjectClosure* is_alive) {
+ #ifdef ASSERT
+   // The class is alive iff the class loader is alive.
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/oops/klass.hpp
+--- a/src/share/vm/oops/klass.hpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/oops/klass.hpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -149,6 +149,10 @@
+   oop       _java_mirror;
+   // Superclass
+   Klass*      _super;
++  // Old class
++  Klass*      _old_version;
++  // New class
++  Klass*      _new_version;
+   // First subclass (NULL if none); _subklass->next_sibling() is next one
+   Klass*      _subklass;
+   // Sibling link (or NULL); links all subklasses of a klass
+@@ -164,6 +168,16 @@
+   jint        _modifier_flags;  // Processed access flags, for use by Class.getModifiers.
+   AccessFlags _access_flags;    // Access flags. The class/interface distinction is stored here.
+ 
++  // (DCEVM) 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?
++  bool        _original_field_offsets_changed; // Did the original field offsets of this class change during class redefinition?
++  int *       _update_information;     // Update information
++  bool        _is_redefining;
++
+   // Biased locking implementation and statistics
+   // (the 64-bit chunk goes first, to avoid some fragmentation)
+   jlong    _last_biased_lock_bulk_revocation_time;
+@@ -223,6 +237,53 @@
+   Array<Klass*>* secondary_supers() const { return _secondary_supers; }
+   void set_secondary_supers(Array<Klass*>* k) { _secondary_supers = k; }
+ 
++  // BEGIN class redefinition utilities
++
++  // double links between new and old version of a class
++  Klass* old_version() const                           { return _old_version; }
++  void set_old_version(Klass* klass)                   { assert(_old_version == NULL || klass == NULL, "Can only be set once!"); _old_version = klass; }
++  Klass* new_version() const                           { return _new_version; }
++  void set_new_version(Klass* 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()->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; }
++  void set_redefinition_flag(int flag)                 { _redefinition_flags |= flag; }
++  void clear_redefinition_flag(int flag)               { _redefinition_flags &= ~flag; }
++  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; }
++
++  // Revision number for redefined classes, -1 for originally loaded classes
++  bool was_redefined() const            { return _revision_number != -1; }
++  jint revision_number() const          { return _revision_number; }
++  void set_revision_number(jint number) { _revision_number = number; }
++
++  const Klass* oldest_version() const   { return _old_version == NULL ? this : _old_version->oldest_version(); }
++        Klass* oldest_version()         { return _old_version == NULL ? this : _old_version->oldest_version(); }
++
++  const Klass* newest_version() const   { return _new_version == NULL ? this : _new_version->newest_version(); }
++        Klass* newest_version()         { return _new_version == NULL ? this : _new_version->newest_version(); }
++
++  const Klass* active_version() const   { return _new_version == NULL || _new_version->is_redefining() ? this : _new_version->active_version(); }
++        Klass* active_version()         { return _new_version == NULL || _new_version->is_redefining() ? this : _new_version->active_version(); }
++
++  bool is_newest_version() const        { return _new_version == NULL; }
++
++  // END class redefinition utilities
++
+   // Return the element of the _super chain of the given depth.
+   // If there is no such element, return either NULL or this.
+   Klass* primary_super_of_depth(juint i) const {
+@@ -276,6 +337,7 @@
+   Klass* subklass() const;
+   Klass* next_sibling() const;
+   void append_to_sibling_list();           // add newly created receiver to superklass' subklass list
++  void remove_from_sibling_list();         // (DCEVM) remove receiver from sibling list
+ 
+   void set_next_link(Klass* k) { _next_link = k; }
+   Klass* next_link() const { return _next_link; }   // The next klass defined by the class loader.
+@@ -311,6 +373,16 @@
+   void     set_next_sibling(Klass* s);
+ 
+  public:
++  // (DCEVM) Different class redefinition flags of code evolution.
++  enum RedefinitionFlags {
++    NoRedefinition,                             // This class is not redefined at all!
++    ModifyClass = 1,                            // There are changes to the class meta data.
++    ModifyClassSize = ModifyClass << 1,         // The size of the class meta data changes.
++    ModifyInstances = ModifyClassSize << 1,     // There are change to the instance format.
++    ModifyInstanceSize = ModifyInstances << 1,  // The size of instances changes.
++    RemoveSuperType = ModifyInstanceSize << 1,  // A super type of this class is removed.
++    MarkedAsAffected = RemoveSuperType << 1     // This class has been marked as an affected class.
++  };
+ 
+   // Compiler support
+   static ByteSize super_offset()                 { return in_ByteSize(offset_of(Klass, _super)); }
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/oops/klassVtable.cpp
+--- a/src/share/vm/oops/klassVtable.cpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/oops/klassVtable.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -1534,6 +1534,8 @@
+ 
+ void klassVtable::verify_against(outputStream* st, klassVtable* vt, int index) {
+   vtableEntry* vte = &vt->table()[index];
++  // (DCEVM) FIXME-isd: do we need the following line?
++  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");
+@@ -1553,6 +1555,8 @@
+ 
+ void vtableEntry::verify(klassVtable* vt, outputStream* st) {
+   NOT_PRODUCT(FlagSetting fs(IgnoreLockingAssertions, true));
++  // FIXME: (DCEVM) 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
+@@ -1560,7 +1564,9 @@
+ #ifndef PRODUCT
+     print();
+ #endif
+-    fatal(err_msg("vtableEntry " PTR_FORMAT ": method is from subclass", this));
++    // (DCEVM) the following fatal does not work for old versions of classes
++    //fatal(err_msg("vtableEntry " PTR_FORMAT ": method is from subclass", this));
++  }
+   }
+ }
+ 
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/oops/method.cpp
+--- a/src/share/vm/oops/method.cpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/oops/method.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -1231,6 +1231,8 @@
+ 
+   // Reset correct method/const method, method size, and parameter info
+   newm->set_constMethod(newcm);
++  newm->set_new_version(newm->new_version());
++  newm->set_old_version(newm->old_version());
+   newm->constMethod()->set_code_size(new_code_length);
+   newm->constMethod()->set_constMethod_size(new_const_method_size);
+   newm->set_method_size(new_method_size);
+@@ -1846,6 +1848,10 @@
+ 
+ // Add a method id to the jmethod_ids
+ jmethodID Method::make_jmethod_id(ClassLoaderData* loader_data, Method* m) {
++  // FIXME: (DCEVM) ???
++  if (m != m->newest_version()) {
++    m = m->newest_version();
++  }
+   ClassLoaderData* cld = loader_data;
+ 
+   if (!SafepointSynchronize::is_at_safepoint()) {
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/oops/method.hpp
+--- a/src/share/vm/oops/method.hpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/oops/method.hpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -104,6 +104,9 @@
+   MethodCounters*   _method_counters;
+   AccessFlags       _access_flags;               // Access flags
+   int               _vtable_index;               // vtable index of this method (see VtableIndexFlag)
++  // (DCEVM) Newer version of method available?
++  Method*           _new_version;
++  Method*           _old_version;
+                                                  // note: can have vtables with >2**16 elements (because of inheritance)
+   u2                _method_size;                // size of this object
+   u1                _intrinsic_id;               // vmSymbols::intrinsic_id (0 == _none)
+@@ -176,6 +179,23 @@
+   int name_index() const                         { return constMethod()->name_index();         }
+   void set_name_index(int index)                 { constMethod()->set_name_index(index);       }
+ 
++  Method* new_version() const                    { return _new_version; }
++  void set_new_version(Method* m)                { _new_version = m; }
++  Method* newest_version()                       { return (_new_version == NULL) ? this : _new_version->newest_version(); }
++
++  Method* old_version() const                    { return _old_version; }
++  void set_old_version(Method* 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;
++  }
++  const Method* oldest_version() const           { return (_old_version == NULL) ? this : _old_version->oldest_version(); }
++
+   // signature
+   Symbol* signature() const                      { return constants()->symbol_at(signature_index()); }
+   int signature_index() const                    { return constMethod()->signature_index();         }
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/prims/jni.cpp
+--- a/src/share/vm/prims/jni.cpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/prims/jni.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -399,6 +399,7 @@
+   }
+   Klass* k = SystemDictionary::resolve_from_stream(class_name, class_loader,
+                                                      Handle(), &st, true,
++                                                     KlassHandle(),
+                                                      CHECK_NULL);
+ 
+   if (TraceClassResolution && k != NULL) {
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/prims/jvm.cpp
+--- a/src/share/vm/prims/jvm.cpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/prims/jvm.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -1141,6 +1141,7 @@
+   Klass* k = SystemDictionary::resolve_from_stream(class_name, class_loader,
+                                                      protection_domain, &st,
+                                                      verify != 0,
++                                                     KlassHandle(),
+                                                      CHECK_NULL);
+ 
+   if (TraceClassResolution && k != NULL) {
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/prims/jvmtiEnv.cpp
+--- a/src/share/vm/prims/jvmtiEnv.cpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/prims/jvmtiEnv.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -43,6 +43,7 @@
+ #include "prims/jvmtiManageCapabilities.hpp"
+ #include "prims/jvmtiRawMonitor.hpp"
+ #include "prims/jvmtiRedefineClasses.hpp"
++#include "prims/jvmtiRedefineClasses2.hpp"
+ #include "prims/jvmtiTagMap.hpp"
+ #include "prims/jvmtiThreadState.inline.hpp"
+ #include "prims/jvmtiUtil.hpp"
+@@ -207,8 +208,10 @@
+ // is_modifiable_class_ptr - pre-checked for NULL
+ jvmtiError
+ JvmtiEnv::IsModifiableClass(oop k_mirror, jboolean* is_modifiable_class_ptr) {
+-  *is_modifiable_class_ptr = VM_RedefineClasses::is_modifiable_class(k_mirror)?
+-                                                       JNI_TRUE : JNI_FALSE;
++  bool is_modifiable_class = AllowEnhancedClassRedefinition ?
++    VM_EnhancedRedefineClasses::is_modifiable_class(k_mirror) :
++    VM_RedefineClasses::is_modifiable_class(k_mirror);
++  *is_modifiable_class_ptr = is_modifiable_class ? JNI_TRUE : JNI_FALSE;
+   return JVMTI_ERROR_NONE;
+ } /* end IsModifiableClass */
+ 
+@@ -277,6 +280,11 @@
+     }
+     class_definitions[index].klass              = jcls;
+   }
++  if (AllowEnhancedClassRedefinition) {
++    VM_EnhancedRedefineClasses op(class_count, class_definitions, jvmti_class_load_kind_retransform);
++    VMThread::execute(&op);
++    return (op.check_error());
++  }
+   VM_RedefineClasses op(class_count, class_definitions, jvmti_class_load_kind_retransform);
+   VMThread::execute(&op);
+   return (op.check_error());
+@@ -288,6 +296,11 @@
+ jvmtiError
+ JvmtiEnv::RedefineClasses(jint class_count, const jvmtiClassDefinition* class_definitions) {
+ //TODO: add locking
++  if (AllowEnhancedClassRedefinition) {
++    VM_EnhancedRedefineClasses op(class_count, class_definitions, jvmti_class_load_kind_redefine);
++    VMThread::execute(&op);
++    return (op.check_error());
++  }
+   VM_RedefineClasses op(class_count, class_definitions, jvmti_class_load_kind_redefine);
+   VMThread::execute(&op);
+   return (op.check_error());
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/prims/jvmtiExport.hpp
+--- a/src/share/vm/prims/jvmtiExport.hpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/prims/jvmtiExport.hpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -188,6 +188,7 @@
+   // systems as needed to relax invariant checks.
+   static bool _has_redefined_a_class;
+   friend class VM_RedefineClasses;
++  friend class VM_EnhancedRedefineClasses;
+   inline static void set_has_redefined_a_class() {
+     JVMTI_ONLY(_has_redefined_a_class = true;)
+   }
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/prims/jvmtiGetLoadedClasses.cpp
+--- a/src/share/vm/prims/jvmtiGetLoadedClasses.cpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/prims/jvmtiGetLoadedClasses.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -59,8 +59,14 @@
+ 
+   void do_klass(Klass* k) {
+     // Collect all jclasses
+-    _classStack.push((jclass) _env->jni_reference(k->java_mirror()));
+-    ensure_klass_alive(k->java_mirror());
++    // DCEVM : LoadedClassesClosure in dcevm7 iterates over classes from SystemDictionary therefore the class "k" is always
++    //         the new version (SystemDictionary stores only new versions). But the LoadedClassesClosure's functionality was
++    //         changed in java8  where jvmtiLoadedClasses collects all classes from all classloaders, therefore we
++    //         must use new versions only.
++    if (k->new_version()==NULL) {      
++        _classStack.push((jclass) _env->jni_reference(k->java_mirror()));
++        ensure_klass_alive(k->java_mirror());
++    }
+   }
+ 
+   int extract(jclass* result_list) {
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/prims/jvmtiImpl.cpp
+--- a/src/share/vm/prims/jvmtiImpl.cpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/prims/jvmtiImpl.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -288,6 +288,11 @@
+   Symbol* m_name = _method->name();
+   Symbol* m_signature = _method->signature();
+ 
++  // (DCEVM) Go through old versions of method
++  for (Method* m = _method->old_version(); m != NULL; m = m->old_version()) {
++    (m->*meth_act)(_bci);
++  }
++
+   // search previous versions if they exist
+   for (InstanceKlass* pv_node = ikh->previous_versions();
+        pv_node != NULL;
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/prims/jvmtiRedefineClasses2.cpp
+--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
++++ b/src/share/vm/prims/jvmtiRedefineClasses2.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -0,0 +1,2119 @@
++/*
++ * 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.
++ *
++ */
++
++#include "precompiled.hpp"
++#include "classfile/systemDictionary.hpp"
++#include "classfile/verifier.hpp"
++#include "code/codeCache.hpp"
++#include "interpreter/oopMapCache.hpp"
++#include "interpreter/rewriter.hpp"
++#include "memory/gcLocker.hpp"
++#include "memory/universe.inline.hpp"
++#include "memory/metaspaceShared.hpp"
++#include "oops/fieldStreams.hpp"
++#include "oops/klassVtable.hpp"
++#include "prims/jvmtiImpl.hpp"
++#include "prims/jvmtiRedefineClasses2.hpp"
++#include "prims/methodComparator.hpp"
++#include "prims/jvmtiClassFileReconstituter.hpp"
++#include "runtime/deoptimization.hpp"
++#include "runtime/relocator.hpp"
++#include "utilities/bitMap.inline.hpp"
++#include "compiler/compileBroker.hpp"
++#include "oops/instanceMirrorKlass.hpp"
++#include "utilities/pair.hpp"
++
++
++Array<Method*>* VM_EnhancedRedefineClasses::_old_methods = NULL;
++Array<Method*>* VM_EnhancedRedefineClasses::_new_methods = NULL;
++int*        VM_EnhancedRedefineClasses::_matching_old_methods = NULL;
++int*        VM_EnhancedRedefineClasses::_matching_new_methods = NULL;
++int*        VM_EnhancedRedefineClasses::_deleted_methods      = NULL;
++int*        VM_EnhancedRedefineClasses::_added_methods        = NULL;
++int         VM_EnhancedRedefineClasses::_matching_methods_length = 0;
++int         VM_EnhancedRedefineClasses::_deleted_methods_length  = 0;
++int         VM_EnhancedRedefineClasses::_added_methods_length    = 0;
++GrowableArray<instanceKlassHandle>* VM_EnhancedRedefineClasses::_affected_klasses = NULL;
++
++
++// Holds the revision number of the current class redefinition
++int    VM_EnhancedRedefineClasses::_revision_number = -1;
++
++VM_EnhancedRedefineClasses::VM_EnhancedRedefineClasses(jint class_count, const jvmtiClassDefinition *class_defs, JvmtiClassLoadKind class_load_kind)
++   : VM_GC_Operation(Universe::heap()->total_full_collections(), GCCause::_heap_inspection) {
++  RC_TIMER_START(_timer_total);
++  _class_count = class_count;
++  _class_defs = class_defs;
++  _class_load_kind = class_load_kind;
++  _result = JVMTI_ERROR_NONE;
++}
++
++VM_EnhancedRedefineClasses::~VM_EnhancedRedefineClasses() {
++  RC_TIMER_STOP(_timer_total);
++}
++
++void VM_EnhancedRedefineClasses::add_affected_klasses( Klass* klass )
++{
++  assert(!_affected_klasses->contains(klass), "must not occur more than once!");
++  assert(klass->new_version() == NULL, "Only last version is valid entry in system dictionary");
++
++  if (klass->check_redefinition_flag(Klass::MarkedAsAffected)) {
++    _affected_klasses->append(klass);
++    return;
++  }
++
++  for (juint i = 0; i < klass->super_depth(); i++) {
++    Klass* primary = klass->primary_super_of_depth(i);
++    // super_depth returns "8" for interfaces, but they don't have primaries other than Object.
++    if (primary == NULL) {
++      break;
++    }
++    if (primary->check_redefinition_flag(Klass::MarkedAsAffected)) {
++      RC_TRACE(0x00000001, ("Found affected class: %s", klass->name()->as_C_string()));
++      klass->set_redefinition_flag(Klass::MarkedAsAffected);
++      _affected_klasses->append(klass);
++      return;
++    }
++  }
++
++  // Check secondary supers
++  int cnt = klass->secondary_supers()->length();
++  for (int i = 0; i < cnt; i++) {
++    Klass* secondary = klass->secondary_supers()->at(i);
++    if (secondary->check_redefinition_flag(Klass::MarkedAsAffected)) {
++      RC_TRACE(0x00000001, ("Found affected class: %s", klass->name()->as_C_string()));
++      klass->set_redefinition_flag(Klass::MarkedAsAffected);
++      _affected_klasses->append(klass);
++      return;
++    }
++  }
++}
++
++
++// Searches for all affected classes and performs a sorting such that a supertype is always before a subtype.
++jvmtiError VM_EnhancedRedefineClasses::find_sorted_affected_classes() {
++
++  assert(_affected_klasses, "");
++  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_Klass(mirror));
++    klass_handle->set_redefinition_flag(Klass::MarkedAsAffected);
++    assert(klass_handle->new_version() == NULL, "Must be new class");
++    RC_TRACE(0x00000001, ("Class being reloaded: %s", klass_handle->name()->as_C_string()));
++  }
++
++  // Find classes not directly redefined, but affected by a redefinition (because one of its supertypes is redefined)
++  SystemDictionary::classes_do(VM_EnhancedRedefineClasses::add_affected_klasses);
++  RC_TRACE(0x00000001, ("%d classes affected", _affected_klasses->length()));
++
++  // 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, Thread::current());
++  if (RC_TRACE_ENABLED(0x00000001)) {
++    RC_TRACE(0x00000001, ("Redefine order: "));
++    for (int i = 0; i < _affected_klasses->length(); i++) {
++      RC_TRACE(0x00000001, ("%s", _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_EnhancedRedefineClasses::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);
++    Klass* the_class_oop = java_lang_Class::as_Klass(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());
++      MonitorLockerEx ml(constants->lock());            // lock constant pool while we query it
++      //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_EnhancedRedefineClasses::doit_prologue() {
++
++  _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;
++  }
++
++  // 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, mtInternal) GrowableArray<instanceKlassHandle>(5, true);
++
++  assert(_affected_klasses == NULL, "");
++  _affected_klasses = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<instanceKlassHandle>(_class_count, 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;
++    delete _affected_klasses;
++    _affected_klasses = NULL;
++    RC_TIMER_STOP(_timer_prologue);
++    return false;
++  }
++
++  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.
++jvmtiError VM_EnhancedRedefineClasses::check_arguments_error() {
++  if (_class_defs == NULL) return JVMTI_ERROR_NULL_POINTER;
++  for (int i = 0; i < _class_count; i++) {
++    if (_class_defs[i].klass == NULL) return JVMTI_ERROR_INVALID_CLASS;
++    if (_class_defs[i].class_byte_count == 0) return JVMTI_ERROR_INVALID_CLASS_FORMAT;
++    if (_class_defs[i].class_bytes == NULL) return JVMTI_ERROR_NULL_POINTER;
++  }
++  return JVMTI_ERROR_NONE;
++  }
++
++// Returns false and sets an result error code if the redefinition should be aborted.
++bool VM_EnhancedRedefineClasses::check_arguments() {
++  jvmtiError error = check_arguments_error();
++  if (error != JVMTI_ERROR_NONE || _class_count == 0) {
++    _result = error;
++    return false;
++  }
++  return true;
++}
++
++jvmtiError VM_EnhancedRedefineClasses::check_exception() const {
++  Thread* THREAD = Thread::current();
++  if (HAS_PENDING_EXCEPTION) {
++
++    Symbol* ex_name = PENDING_EXCEPTION->klass()->name();
++    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;
++    }
++  }
++
++  return JVMTI_ERROR_NONE;
++}
++
++// Loads all new class versions and stores the InstanceKlass handles in an array.
++jvmtiError VM_EnhancedRedefineClasses::load_new_class_versions(TRAPS) {
++
++  ResourceMark rm(THREAD);
++
++  RC_TRACE(0x00000001,
++        ("loading new class versions (%d)", _class_count));
++
++  // Retrieve an array of all classes that need to be redefined
++  jvmtiError err = find_sorted_affected_classes();
++  if (err != JVMTI_ERROR_NONE) {
++    RC_TRACE(0x00000001,
++          ("Error finding sorted affected classes: %d", (int)err));
++    return err;
++  }
++
++
++  JvmtiThreadState *state = JvmtiThreadState::state_for(JavaThread::current());
++
++  _max_redefinition_flags = Klass::NoRedefinition;
++  jvmtiError result = JVMTI_ERROR_NONE;
++
++  for (int i = 0; i < _affected_klasses->length(); i++) {
++    instanceKlassHandle the_class = _affected_klasses->at(i);
++
++    RC_TRACE(0x00000001,
++            ("Processing affected class %s (%d of %d)",
++                the_class->name()->as_C_string(),
++                i + 1,
++                _affected_klasses->length()));
++
++    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_WITH_THREAD(0x00000002, THREAD,
++            ("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_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());
++    ClassFileStream st((u1*) class_bytes, class_byte_count, (char *)"__VM_EhnancedRedefineClasses__");
++
++    Klass* klass =
++        SystemDictionary::resolve_from_stream(
++            the_class->name(),
++            the_class_loader,
++            protection_domain,
++            &st,
++            true,
++            the_class,
++            THREAD);
++    instanceKlassHandle new_class(THREAD, klass);
++
++    RC_TIMER_STOP(_timer_class_loading);
++    RC_TIMER_START(_timer_prologue);
++
++    // Clear class_being_redefined just to be sure.
++    state->clear_class_being_redefined();
++
++    result = check_exception();
++    if (result != JVMTI_ERROR_NONE) break;
++
++    not_changed = false;
++
++#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, "");
++
++
++    Array<Klass*>* k_interfaces = new_class->local_interfaces();
++    for (int j = 0; j < k_interfaces->length(); j++) {
++      assert(k_interfaces->at(j)->is_newest_version(), "just checking");
++    }
++
++    if (!THREAD->is_Compiler_thread()) {
++      RC_TRACE(0x00000001, ("name=%s loader="INTPTR_FORMAT" protection_domain="INTPTR_FORMAT,
++                                               the_class->name()->as_C_string(),
++                                               (intptr_t) (oopDesc*) the_class->class_loader(),
++                                               (intptr_t) (oopDesc*) the_class->protection_domain()));
++      // If we are on the compiler thread, we must not try to resolve a class.
++      Klass* 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()->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 {
++      redefinition_flags = calculate_redefinition_flags(new_class);
++      if (redefinition_flags >= Klass::RemoveSuperType) {
++        result = JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED;
++        break;
++      }
++    }
++
++    if (new_class->super() != NULL) {
++      redefinition_flags = redefinition_flags | new_class->super()->redefinition_flags();
++    }
++
++    for (int j = 0; j<new_class->local_interfaces()->length(); j++) {
++      redefinition_flags = redefinition_flags | (new_class->local_interfaces()->at(j))->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 {
++      // Fields were not changed, transfer special flags only
++      assert(new_class->layout_helper() >> 1 == new_class->old_version()->layout_helper() >> 1, "must be equal");
++      assert(new_class->fields()->length() == InstanceKlass::cast(new_class->old_version())->fields()->length(), "must be equal");
++      
++      JavaFieldStream old_fs(the_class);
++      JavaFieldStream new_fs(new_class);
++      for (; !old_fs.done() && !new_fs.done(); old_fs.next(), new_fs.next()) {
++        AccessFlags flags = new_fs.access_flags();
++        flags.set_is_field_modification_watched(old_fs.access_flags().is_field_modification_watched());
++        flags.set_is_field_access_watched(old_fs.access_flags().is_field_access_watched());
++        new_fs.set_access_flags(flags);
++      }
++    }
++
++    if (RC_TRACE_ENABLED(0x00000001)) {
++      RC_TRACE(0x00000001,
++            ("Super class is %s", new_class->super()->name()->as_C_string()));
++    }
++
++#ifdef ASSERT
++    assert(new_class->super() == NULL || new_class->super()->new_version() == NULL, "Super klass must be newest version!");
++
++    the_class->vtable()->verify(tty);
++    new_class->vtable()->verify(tty);
++#endif
++
++    if (i == _affected_klasses->length() - 1) {
++      // This was the last class processed => check if additional classes have been loaded in the meantime
++      for (int j = 0; j<_affected_klasses->length(); j++) {
++
++        Klass* initial_klass = _affected_klasses->at(j)();
++        Klass *initial_subklass = initial_klass->subklass();
++        Klass *cur_klass = initial_subklass;
++        while(cur_klass != NULL) {
++
++          if(cur_klass->oop_is_instance() && cur_klass->is_newest_version() && !cur_klass->is_redefining()) {
++            instanceKlassHandle handle(THREAD, cur_klass);
++            if (!_affected_klasses->contains(handle)) {
++
++              int k = i + 1;
++              for (; k<_affected_klasses->length(); k++) {
++                if (_affected_klasses->at(k)->is_subtype_of(cur_klass)) {
++                  break;
++                }
++              }
++              _affected_klasses->insert_before(k, handle);
++              RC_TRACE(0x00000001,
++                    ("Adding newly loaded class to affected classes: %s", cur_klass->name()->as_C_string()));
++            }
++      }
++
++          cur_klass = cur_klass->next_sibling();
++        }
++      }
++
++      int new_count = _affected_klasses->length() - 1 - i;
++      if (new_count != 0) {
++        RC_TRACE(0x00000001,
++              ("Found new number of affected classes: %d", new_count));
++      }
++    }
++  }
++
++  if (result != JVMTI_ERROR_NONE) {
++    rollback();
++    return result;
++  }
++
++  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<_affected_klasses->length(); i++) {
++    instanceKlassHandle the_class = _affected_klasses->at(i);
++    instanceKlassHandle new_class(the_class->new_version());
++
++    RC_TRACE(0x00000001,
++          ("Linking class %d/%d %s", i, _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(0x00000001, ("All classes loaded!"));
++
++#ifdef ASSERT
++  for (int i=0; i<_affected_klasses->length(); i++) {
++    instanceKlassHandle the_class = _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()->new_version() == NULL)) {
++      new_version()->print();
++      new_version->super()->print();
++    }
++    assert(new_version->super() == NULL || new_version->super()->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;
++}
++
++int VM_EnhancedRedefineClasses::calculate_redefinition_flags(instanceKlassHandle new_class) {
++
++  int result = Klass::NoRedefinition;
++  RC_TRACE(0x00000001,
++        ("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);
++  }
++
++  int i;
++
++  //////////////////////////////////////////////////////////////////////////////////////////////////////////
++  // Check superclasses
++  assert(new_class->super() == NULL || new_class->super()->is_newest_version(), "");
++  if (the_class->super() != new_class->super()) {
++    // Super class changed
++    Klass* cur_klass = the_class->super();
++    while (cur_klass != NULL) {
++      if (!new_class->is_subclass_of(cur_klass->newest_version())) {
++        RC_TRACE(0x00000001,
++              ("Removed super class %s", cur_klass->name()->as_C_string()));
++        result = result | Klass::RemoveSuperType | Klass::ModifyInstances | Klass::ModifyClass;
++
++        if (!cur_klass->has_subtype_changed()) {
++          RC_TRACE(0x00000001,
++                ("Subtype changed of class %s", cur_klass->name()->as_C_string()));
++          cur_klass->set_subtype_changed(true);
++        }
++  }
++
++      cur_klass = cur_klass->super();
++  }
++
++    cur_klass = new_class->super();
++    while (cur_klass != NULL) {
++      if (!the_class->is_subclass_of(cur_klass->old_version())) {
++        RC_TRACE(0x00000001,
++              ("Added super class %s", cur_klass->name()->as_C_string()));
++        result = result | Klass::ModifyClass | Klass::ModifyInstances;
++      }
++      cur_klass = cur_klass->super();
++    }
++  }
++
++  //////////////////////////////////////////////////////////////////////////////////////////////////////////
++  // Check interfaces
++
++  // Interfaces removed?
++  Array<Klass*>* old_interfaces = the_class->transitive_interfaces();
++  for (i = 0; i<old_interfaces->length(); i++) {
++    instanceKlassHandle old_interface(old_interfaces->at(i));
++    if (!new_class->implements_interface_any_version(old_interface())) {
++      result = result | Klass::RemoveSuperType | Klass::ModifyClass;
++      RC_TRACE(0x00000001,
++            ("Removed interface %s", old_interface->name()->as_C_string()));
++
++      if (!old_interface->has_subtype_changed()) {
++        RC_TRACE(0x00000001,
++              ("Subtype changed of interface %s", old_interface->name()->as_C_string()));
++        old_interface->set_subtype_changed(true);
++      }
++    }
++  }
++
++  // Interfaces added?
++  Array<Klass*>* new_interfaces = new_class->transitive_interfaces();
++  for (i = 0; i<new_interfaces->length(); i++) {
++    if (!the_class->implements_interface_any_version(new_interfaces->at(i))) {
++      result = result | Klass::ModifyClass;
++      RC_TRACE(0x00000001,
++            ("Added interface %s", new_interfaces->at(i)->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 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) {
++      // TODO can this have any effect?
++    }
++    // 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 both streams aren't done then we have a differing number of
++  // fields.
++  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.
++  Array<Method*>* k_old_methods(the_class->methods()); // FIXME-isd: handles???
++  Array<Method*>* 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) {
++    Method* k_old_method;
++    Method* 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 = k_new_methods->at(ni);
++      method_was = added;
++    } else if (ni >= n_new_methods) {
++      // Old method, at the end, is deleted
++      k_old_method = k_old_methods->at(oi);
++      method_was = deleted;
++    } else {
++      // There are more methods in both the old and new lists
++      k_old_method = k_old_methods->at(oi);
++      k_new_method = k_new_methods->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 {
++          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++) {
++            Method* m = k_new_methods->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->at_put(ni, m);
++            k_new_methods->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;
++        }
++      }
++    }
++
++    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)) {
++      // TODO Can this have any effects? Probably yes on vtables?
++      result = result | Klass::ModifyClass;
++    }
++    {
++      u2 new_num = k_new_method->method_idnum();
++      u2 old_num = k_old_method->method_idnum();
++      if (new_num != old_num) {
++        Method* 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(0x00008000,
++            ("swapping idnum of new and old method %d / %d!", new_num, old_num));
++      }
++    }
++    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;
++    }
++    {
++      u2 num = new_class->next_method_idnum();
++      if (num == ConstMethod::UNSET_IDNUM) {
++        // cannot add any more methods
++        result = result | Klass::ModifyClass;
++      }
++      u2 new_num = k_new_method->method_idnum();
++      Method* 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);
++    }
++    RC_TRACE(0x00008000, ("Method added: new: %s [%d], idnum %d",
++                         k_new_method->name_and_sig_as_C_string(), ni, k_new_method->method_idnum()));
++    ++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(0x00008000, ("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()))->size_helper()) {
++    result |= Klass::ModifyInstanceSize;
++  }
++
++  // TODO Check method bodies to be able to return NoChange?
++  return result;
++}
++
++void VM_EnhancedRedefineClasses::calculate_instance_update_information(Klass* new_version) {
++
++  class CalculateFieldUpdates : public FieldClosure {
++
++  private:
++    InstanceKlass* _old_ik;
++    GrowableArray<int> _update_info;
++    int _position;
++    bool _copy_backwards;
++
++  public:
++
++    bool does_copy_backwards() {
++      return _copy_backwards;
++  }
++
++    CalculateFieldUpdates(InstanceKlass* old_ik) :
++        _old_ik(old_ik), _position(instanceOopDesc::base_offset_in_bytes()), _copy_backwards(false) {
++      _update_info.append(_position);
++      _update_info.append(0);
++  }
++
++    GrowableArray<int> &finish() {
++      _update_info.append(0);
++      return _update_info;
++  }
++
++    void do_field(fieldDescriptor* fd) {
++      int alignment = fd->offset() - _position;
++      if (alignment > 0) {
++        // This field was aligned, so we need to make sure that we fill the gap
++        fill(alignment);
++      }
++
++      assert(_position == fd->offset(), "must be correct offset!");
++
++      fieldDescriptor old_fd;
++      if (_old_ik->find_field(fd->name(), fd->signature(), false, &old_fd) != NULL) {
++        // Found field in the old class, copy
++        copy(old_fd.offset(), type2aelembytes(fd->field_type()));
++
++        if (old_fd.offset() < fd->offset()) {
++          _copy_backwards = true;
++        }
++
++        // Transfer special flags
++        fd->set_is_field_modification_watched(old_fd.is_field_modification_watched());
++        fd->set_is_field_access_watched(old_fd.is_field_access_watched());
++      } else {
++        // New field, fill
++        fill(type2aelembytes(fd->field_type()));
++      }
++  }
++
++  private:
++
++    void fill(int size) {
++      if (_update_info.length() > 0 && _update_info.at(_update_info.length() - 1) < 0) {
++        (*_update_info.adr_at(_update_info.length() - 1)) -= size;
++      } else {
++        _update_info.append(-size);
++      }
++      _position += size;
++    }
++
++    void copy(int offset, int size) {
++      int prev_end = -1;
++      if (_update_info.length() > 0 && _update_info.at(_update_info.length() - 1) > 0) {
++        prev_end = _update_info.at(_update_info.length() - 2) + _update_info.at(_update_info.length() - 1);
++      }
++
++      if (prev_end == offset) {
++        (*_update_info.adr_at(_update_info.length() - 2)) += size;
++      } else {
++        _update_info.append(size);
++        _update_info.append(offset);
++      }
++
++      _position += size;
++    }
++  };
++
++  InstanceKlass* ik = InstanceKlass::cast(new_version);
++  InstanceKlass* old_ik = InstanceKlass::cast(new_version->old_version());
++  CalculateFieldUpdates cl(old_ik);
++  ik->do_nonstatic_fields(&cl);
++
++  GrowableArray<int> result = cl.finish();
++  ik->store_update_information(result);
++  ik->set_copying_backwards(cl.does_copy_backwards());
++
++
++  if (RC_TRACE_ENABLED(0x00000001)) {
++    RC_TRACE(0x00000001, ("Instance update information for %s:", new_version->name()->as_C_string()));
++    if (cl.does_copy_backwards()) {
++      RC_TRACE(0x00000001, ("\tDoes copy backwards!"));
++    }
++    for (int i=0; i<result.length(); i++) {
++      int curNum = result.at(i);
++      if (curNum < 0) {
++        RC_TRACE(0x00000001, ("\t%d CLEAN", curNum));
++      } else if (curNum > 0) {
++        RC_TRACE(0x00000001, ("\t%d COPY from %d", curNum, result.at(i + 1)));
++        i++;
++      } else {
++        RC_TRACE(0x00000001, ("\tEND"));
++      }
++    }
++  }
++}
++
++void VM_EnhancedRedefineClasses::rollback() {
++  RC_TRACE(0x00000001, ("Rolling back redefinition!"));
++  SystemDictionary::rollback_redefinition();
++
++  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()->set_new_version(NULL);
++    new_class->set_old_version(NULL);
++  }
++
++}
++
++void VM_EnhancedRedefineClasses::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);
++}
++
++class FieldCopier : public FieldClosure {
++  public:
++  void do_field(fieldDescriptor* fd) {
++    InstanceKlass* cur = InstanceKlass::cast(fd->field_holder());
++    oop cur_oop = cur->java_mirror();
++
++    InstanceKlass* old = InstanceKlass::cast(cur->old_version());
++    oop old_oop = old->java_mirror();
++
++    fieldDescriptor result;
++    bool found = old->find_local_field(fd->name(), fd->signature(), &result);
++    if (found && result.is_static()) {
++      RC_TRACE(0x00000001, ("Copying static field value for field %s old_offset=%d new_offset=%d",
++                                               fd->name()->as_C_string(), result.offset(), fd->offset()));
++      memcpy(cur_oop->obj_field_addr<HeapWord>(fd->offset()),
++             old_oop->obj_field_addr<HeapWord>(result.offset()),
++             type2aelembytes(fd->field_type()));
++
++      // Static fields may have references to java.lang.Class
++      if (fd->field_type() == T_OBJECT) {
++         oop oop = cur_oop->obj_field(fd->offset());
++         if (oop != NULL && oop->is_instanceMirror()) {
++            Klass* klass = java_lang_Class::as_Klass(oop);
++            if (klass != NULL && klass->oop_is_instance()) {
++              assert(oop == InstanceKlass::cast(klass)->java_mirror(), "just checking");
++              if (klass->new_version() != NULL) {
++                oop = InstanceKlass::cast(klass->new_version())->java_mirror();
++                cur_oop->obj_field_put(fd->offset(), oop);
++              }
++            }
++         }
++        }
++      }
++    }
++};
++
++void VM_EnhancedRedefineClasses::mark_as_scavengable(nmethod* nm) {
++  if (!nm->on_scavenge_root_list()) {
++    CodeCache::add_scavenge_root_nmethod(nm);
++  }
++}
++
++struct StoreBarrier {
++  template <class T> static void oop_store(T* p, oop v) { ::oop_store(p, v); }
++};
++
++struct StoreNoBarrier {
++  template <class T> static void oop_store(T* p, oop v) { oopDesc::encode_store_heap_oop_not_null(p, v); }
++};
++
++template <class S>
++class ChangePointersOopClosure : public ExtendedOopClosure {
++  // import java_lang_invoke_MemberName.*
++  enum {
++    REFERENCE_KIND_SHIFT = java_lang_invoke_MemberName::MN_REFERENCE_KIND_SHIFT,
++    REFERENCE_KIND_MASK  = java_lang_invoke_MemberName::MN_REFERENCE_KIND_MASK,
++  };
++
++
++  bool update_member_name(oop obj) {
++    int flags    =       java_lang_invoke_MemberName::flags(obj);
++    int ref_kind =       (flags >> REFERENCE_KIND_SHIFT) & REFERENCE_KIND_MASK;
++    if (MethodHandles::ref_kind_is_method(ref_kind)) {
++      Method* m = (Method*) java_lang_invoke_MemberName::vmtarget(obj);
++      if (m != NULL && !m->method_holder()->is_newest_version()) {
++        // Let's try to re-resolve method
++        InstanceKlass* newest = InstanceKlass::cast(m->method_holder()->newest_version());
++        Method* new_method = newest->find_method(m->name(), m->signature());
++
++        if (new_method != NULL) {
++          // Note: we might set NULL at this point, which should force AbstractMethodError at runtime
++          CallInfo info(new_method, newest);
++          MethodHandles::init_method_MemberName(obj, info, true);
++        } else {
++          java_lang_invoke_MemberName::set_vmtarget(obj, NULL);
++        }
++      }
++    } else if (MethodHandles::ref_kind_is_field(ref_kind)) {
++      Klass* k = (Klass*) java_lang_invoke_MemberName::vmtarget(obj);
++      if (k == NULL) {
++        return false; // Was cleared before, this MemberName is invalid.
++      }
++
++      if (k != NULL && !k->is_newest_version()) {
++        // Let's try to re-resolve field
++        fieldDescriptor fd;
++        int offset = java_lang_invoke_MemberName::vmindex(obj);
++        bool is_static = MethodHandles::ref_kind_is_static(ref_kind);
++        InstanceKlass* ik = InstanceKlass::cast(k);
++        if (ik->find_local_field_from_offset(offset, is_static, &fd)) {
++          InstanceKlass* newest = InstanceKlass::cast(k->newest_version());
++          fieldDescriptor fd_new;
++          if (newest->find_local_field(fd.name(), fd.signature(), &fd_new)) {
++            MethodHandles::init_field_MemberName(obj, fd_new, MethodHandles::ref_kind_is_setter(ref_kind));
++          } else {
++            // Matching field is not found in new version, not much we can do here.
++            // JVM will crash once faulty MH is invoked.
++            // However, to avoid that all DMH's using this faulty MH are cleared (set to NULL)
++            // Eventually, we probably want to replace them with something more meaningful,
++            // like instance throwing NoSuchFieldError or DMH that will resort to dynamic
++            // field resolution (with possibility of type conversion)
++            java_lang_invoke_MemberName::set_vmtarget(obj, NULL);
++            java_lang_invoke_MemberName::set_vmindex(obj, 0);
++            return false;
++          }
++        }
++      }
++    }
++    return true;
++  }
++
++  bool update_direct_method_handle(oop obj) {
++    // Always update member name first.
++    oop mem_name = java_lang_invoke_DirectMethodHandle::member(obj);
++    if (!update_member_name(mem_name)) {
++      return false;
++    }
++
++    // Here we rely on DirectMethodHandle implementation.
++    // The current implementation caches field offset in $StaticAccessor/$Accessor
++    int flags    =       java_lang_invoke_MemberName::flags(mem_name);
++    int ref_kind =       (flags >> REFERENCE_KIND_SHIFT) & REFERENCE_KIND_MASK;
++    if (MethodHandles::ref_kind_is_field(ref_kind)) {
++      // Note: we don't care about staticBase field (which is java.lang.Class)
++      // It should be processed during normal object update.
++      // Update offset in StaticAccessor
++      int offset = java_lang_invoke_MemberName::vmindex(mem_name);
++      if (offset != 0) { // index of 0 means that field no longer exist
++        if (java_lang_invoke_DirectMethodHandle_StaticAccessor::is_instance(obj)) {
++          java_lang_invoke_DirectMethodHandle_StaticAccessor::set_static_offset(obj, offset);
++        } else if (java_lang_invoke_DirectMethodHandle_Accessor::is_instance(obj)) {
++          java_lang_invoke_DirectMethodHandle_Accessor::set_field_offset(obj, offset);
++        }
++      }
++    }
++    return true;
++  }
++
++  // Forward pointers to InstanceKlass and mirror class to new versions
++  template <class T>
++  inline void do_oop_work(T* p) {
++    oop obj = oopDesc::load_decode_heap_oop(p);
++    if (obj == NULL) {
++      return;
++    }
++    if (obj->is_instanceMirror()) {
++      Klass* klass = java_lang_Class::as_Klass(obj);
++      if (klass != NULL && klass->oop_is_instance()) {
++        assert(obj == InstanceKlass::cast(klass)->java_mirror(), "just checking");
++        if (klass->new_version() != NULL) {
++          obj = InstanceKlass::cast(klass->new_version())->java_mirror();
++          S::oop_store(p, obj);
++        }
++      }
++    }
++
++    // JSR 292 support, uptade java.lang.invoke.MemberName instances
++    if (java_lang_invoke_MemberName::is_instance(obj)) {
++      update_member_name(obj);
++    } else if (java_lang_invoke_DirectMethodHandle::is_instance(obj)) {
++      if (!update_direct_method_handle(obj)) {
++        // DMH is no longer valid, replace it with null reference.
++        // See note above. We probably want to replace this with something more meaningful.
++        S::oop_store(p, NULL);
++      }
++    }
++  }
++
++  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;
++  oop _tmp_obj;
++  int _tmp_obj_size;
++
++public:
++  ChangePointersObjectClosure(OopClosure *closure) : _closure(closure), _needs_instance_update(false), _tmp_obj(NULL), _tmp_obj_size(0) {}
++
++  bool needs_instance_update() {
++    return _needs_instance_update;
++  }
++
++  void copy_to_tmp(oop o) {
++    int size = o->size();
++    if (_tmp_obj_size < size) {
++      _tmp_obj_size = size;
++      _tmp_obj = (oop)resource_allocate_bytes(size * HeapWordSize);
++    }
++    Copy::aligned_disjoint_words((HeapWord*)o, (HeapWord*)_tmp_obj, size);
++  }
++
++  virtual void do_object(oop obj) {
++    // FIXME: if (obj->is_instanceKlass()) return;
++    if (obj->is_instanceMirror()) {
++      // static fields may have references to old java.lang.Class instances, update them
++      // at the same time, we don't want to update other oops in the java.lang.Class
++      // Causes SIGSEGV?
++      //instanceMirrorKlass::oop_fields_iterate(obj, _closure);
++    } else {
++      obj->oop_iterate_no_header(_closure);
++    }
++
++    if (obj->klass()->new_version() != NULL) {
++      Klass* new_klass = obj->klass()->new_version();
++      /* FIXME: if (obj->is_perm()) {
++        _needs_instance_update = true;
++      } else */if(new_klass->update_information() != NULL) {
++        int size_diff = obj->size() - obj->size_given_klass(new_klass);
++
++        // Either new size is bigger or gap is to small to be filled
++        if (size_diff < 0 || (size_diff > 0 && (size_t) size_diff < CollectedHeap::min_fill_size())) {
++          // We need an instance update => set back to old klass
++          _needs_instance_update = true;
++        } else {
++          oop src = obj;
++          if (new_klass->is_copying_backwards()) {
++            copy_to_tmp(obj);
++            src = _tmp_obj;
++          }
++          src->set_klass(obj->klass()->new_version());
++          MarkSweep::update_fields(obj, src, new_klass->update_information());
++
++          if (size_diff > 0) {
++            HeapWord* dead_space = ((HeapWord *)obj) + obj->size();
++            CollectedHeap::fill_with_object(dead_space, size_diff);
++          }
++        }
++      } else {
++        obj->set_klass(obj->klass()->new_version());
++      }
++    }
++  }
++};
++
++
++void VM_EnhancedRedefineClasses::doit() {
++
++  Thread *thread = Thread::current();
++
++  assert((_max_redefinition_flags & Klass::RemoveSuperType) == 0, "removing super types not allowed");
++
++  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 (!MetaspaceShared::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(), (Klass*)NULL), Thread::current());
++
++  // Adjust constantpool caches for all classes
++  // that reference methods of the evolved class.
++  ClearCpoolCacheAndUnpatch clear_cpool_cache(Thread::current());
++  ClassLoaderDataGraph::classes_do(&clear_cpool_cache);
++
++  RC_TIMER_STOP(_timer_prepare_redefinition);
++  RC_TIMER_START(_timer_heap_iteration);
++
++  ChangePointersOopClosure<StoreNoBarrier> oopClosureNoBarrier;
++  ChangePointersOopClosure<StoreBarrier> oopClosure;
++  ChangePointersObjectClosure objectClosure(&oopClosure);
++
++  RC_TRACE(0x00000001, ("Before updating instances"));
++  {
++    // Since we may update oops inside nmethod's code blob to point to java.lang.Class in new generation, we need to
++    // make sure such references are properly recognized by GC. For that, If ScavengeRootsInCode is true, we need to
++    // mark such nmethod's as "scavengable".
++    // For now, mark all nmethod's as scavengable that are not scavengable already
++    if (ScavengeRootsInCode) {
++      CodeCache::nmethods_do(mark_as_scavengable);
++    }
++
++    SharedHeap::heap()->gc_prologue(true);
++    Universe::heap()->object_iterate(&objectClosure);
++    Universe::root_oops_do(&oopClosureNoBarrier);
++    SharedHeap::heap()->gc_epilogue(false);
++  }
++  RC_TRACE(0x00000001, ("After updating instances"));
++
++  for (int i = 0; i < _new_classes->length(); i++) {
++    InstanceKlass* cur = InstanceKlass::cast(_new_classes->at(i)());
++    InstanceKlass* old = InstanceKlass::cast(cur->old_version());
++
++    // Swap marks to have same hashcodes
++    markOop cur_mark = cur->prototype_header();
++    markOop old_mark = old->prototype_header();
++    cur->set_prototype_header(old_mark);
++    old->set_prototype_header(cur_mark);
++
++    //swap_marks(cur, old);
++    swap_marks(cur->java_mirror(), old->java_mirror());
++
++    // Revert pool holder for old version of klass (it was updated by one of ours closure!)
++    old->constants()->set_pool_holder(old);
++
++    Klass* array_klasses = old->array_klasses();
++    if (array_klasses != NULL) {
++      assert(cur->array_klasses() == NULL, "just checking");
++
++      // Transfer the array classes, otherwise we might get cast exceptions when casting array types.
++      // Also, set array klasses element klass.
++      cur->set_array_klasses(array_klasses);
++      ObjArrayKlass::cast(array_klasses)->set_element_klass(cur);
++      ArrayKlass::cast(array_klasses)->set_component_mirror(cur->java_mirror());
++    }
++
++    // 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.
++    FieldCopier copier;
++    cur->do_local_static_fields(&copier); // TODO (tw): What about internal static fields??
++    //java_lang_Class::set_klass(old->java_mirror(), cur); // FIXME-isd: is that correct?
++    //FIXME-isd: do we need this: ??? old->set_java_mirror(cur->java_mirror());
++
++    // Transfer init state
++    InstanceKlass::ClassState state = old->init_state();
++    if (state > InstanceKlass::linked) {
++      cur->set_init_state(state);
++    }
++  }
++
++  RC_TIMER_STOP(_timer_heap_iteration);
++  RC_TIMER_START(_timer_redefinition);
++  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);
++    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!"));
++  }
++
++  // Unmark Klass*s as "redefining"
++  for (int i=0; i<_new_classes->length(); i++) {
++    Klass* cur_klass = _new_classes->at(i)();
++    InstanceKlass* cur = (InstanceKlass*)cur_klass;
++    cur->set_redefining(false);
++    cur->clear_update_information();
++  }
++
++  // Disable any dependent concurrent compilations
++  SystemDictionary::notice_modification();
++
++  // Update klass pointers
++  SystemDictionary::update_constraints_after_redefinition();
++
++  // 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
++  ciObjectFactory::resort_shared_ci_metadata();
++
++#ifdef ASSERT
++
++  // Universe::verify();
++  // JNIHandles::verify();
++
++  SystemDictionary::classes_do(check_class, thread);
++#endif
++
++  RC_TIMER_STOP(_timer_redefinition);
++
++  if (TraceRedefineClasses > 0) {
++    tty->flush();
++  }
++}
++
++void VM_EnhancedRedefineClasses::doit_epilogue() {
++
++  RC_TIMER_START(_timer_vm_op_epilogue);
++
++  ResourceMark mark;
++
++  VM_GC_Operation::doit_epilogue();
++  RC_TRACE(0x00000001, ("GC Operation epilogue finished!"));
++
++  // Free the array of scratch classes
++  delete _new_classes;
++  _new_classes = NULL;
++
++  // Free the array of affected classes
++  delete _affected_klasses;
++  _affected_klasses = NULL;
++
++  RC_TRACE(0x00000001, ("Redefinition finished!"));
++
++  RC_TIMER_STOP(_timer_vm_op_epilogue);
++}
++
++bool VM_EnhancedRedefineClasses::is_modifiable_class(oop klass_mirror) {
++  // classes for primitives cannot be redefined
++  if (java_lang_Class::is_primitive(klass_mirror)) {
++    return false;
++  }
++  Klass* klass = java_lang_Class::as_Klass(klass_mirror);
++  // classes for arrays cannot be redefined
++  if (klass == NULL || !klass->oop_is_instance()) {
++    return false;
++  }
++  return true;
++}
++
++#ifdef ASSERT
++
++void VM_EnhancedRedefineClasses::verify_classes(Klass* k_oop_latest, oop initiating_loader, TRAPS) {
++  Klass* k_oop = k_oop_latest;
++  while (k_oop != NULL) {
++
++    instanceKlassHandle k_handle(THREAD, k_oop);
++    Verifier::verify(k_handle, Verifier::ThrowException, true, THREAD);
++    k_oop = k_oop->old_version();
++  }
++}
++
++#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.
++void VM_EnhancedRedefineClasses::unpatch_bytecode(Method* method) {
++  RawBytecodeStream bcs(method);
++  Bytecodes::Code code;
++  Bytecodes::Code java_code;
++  while (!bcs.is_last_bytecode()) {
++    code = bcs.raw_next();
++
++    // dcevm : workaround check _illegal in case of lambda methods etc.
++    // TODO: skip lambda/intrinsic before while loop?  (method()->is_method_handle_intrinsic() || method()->is_compiled_lambda_form())
++    if (code == Bytecodes::_illegal) {
++      return;
++    }
++
++    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);
++      }
++    }
++  }
++
++// 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. 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_EnhancedRedefineClasses::ClearCpoolCacheAndUnpatch::do_klass(Klass* klass) {
++  if (!klass->oop_is_instance()) {
++    return;
++  }
++  HandleMark hm(_thread);
++  InstanceKlass *ik = InstanceKlass::cast(klass);
++  constantPoolHandle other_cp = constantPoolHandle(ik->constants());
++
++  // Update host klass of anonymous classes (for example, produced by lambdas) to newest version.
++  if (ik->is_anonymous() && !ik->host_klass()->is_newest_version()) {
++    ik->set_host_klass(ik->host_klass()->newest_version());
++  }
++
++  for (int i = 0; i < other_cp->length(); i++) {
++    if (other_cp->tag_at(i).is_klass()) {
++      Klass* klass = other_cp->klass_at(i, _thread);
++      if (klass->new_version() != NULL) {
++        // (DCEVM) TODO: check why/if this is necessary
++        other_cp->klass_at_put(i, klass->new_version());
++      }
++      klass = other_cp->klass_at(i, _thread);
++      assert(klass->new_version() == NULL, "Must be new klass!");
++    }
++  }
++
++  ConstantPoolCache* cp_cache = other_cp->cache();
++  if (cp_cache != NULL) {
++    cp_cache->clear_entries();
++  }
++
++  // If bytecode rewriting is enabled, we also need to unpatch bytecode to force resolution of zeroed entries
++  if (RewriteBytecodes) {
++    ik->methods_do(unpatch_bytecode);
++  }
++}
++
++void VM_EnhancedRedefineClasses::update_jmethod_ids() {
++  for (int j = 0; j < _matching_methods_length; ++j) {
++    Method* old_method = _old_methods->at(_matching_old_methods[j]);
++    jmethodID jmid = old_method->find_jmethod_id_or_null();
++    RC_TRACE(0x00008000, ("matching method %s, jmid %d", old_method->name_and_sig_as_C_string(), *((int *)&jmid)));
++    if (old_method->new_version() != NULL && jmid == NULL) {
++       // (DCEVM) 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(_new_methods->at(_matching_new_methods[j]));
++      if (old_method->new_version() == NULL) {
++        methodHandle old_method_h(_old_methods->at(_matching_old_methods[j]));
++        jmethodID new_jmethod_id = Method::make_jmethod_id(old_method_h->method_holder()->class_loader_data(), old_method_h());
++        bool result = InstanceKlass::cast(old_method_h->method_holder())->update_jmethod_id(old_method_h(), new_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);
++      }
++      Method::change_method_associated_with_jmethod_id(jmid, new_method_h());
++      assert(Method::resolve_jmethod_id(jmid) == _new_methods->at(_matching_new_methods[j]), "should be replaced");
++      jmethodID mid = (_new_methods->at(_matching_new_methods[j]))->jmethod_id();
++      //assert(JNIHandles::resolve_non_null((jobject)mid) == new_method_h(), "must match!");
++    }
++  }
++}
++
++
++// 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_EnhancedRedefineClasses::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_EnhancedRedefineClasses::compute_added_deleted_matching_methods() {
++  Method* old_method;
++  Method* 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 = _new_methods->at(nj);
++      _added_methods[_added_methods_length++] = nj;
++      ++nj;
++    } else if (nj >= _new_methods->length()) {
++      // Old method, at the end, is deleted
++      old_method = _old_methods->at(oj);
++      _deleted_methods[_deleted_methods_length++] = oj;
++      ++oj;
++    } else {
++      old_method = _old_methods->at(oj);
++      new_method = _new_methods->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;
++          _matching_methods_length++;
++          ++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_EnhancedRedefineClasses::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()->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
++
++  /* FIXME
++  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();
++  compute_added_deleted_matching_methods();
++
++  // track which methods are EMCP for add_previous_version() call below
++
++  // 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();
++
++  // TODO:
++  transfer_old_native_function_registrations(the_old_class);
++
++  // JSR-292 support
++
++  // Swap method handles
++  MemberNameTable* mnt = the_old_class->member_names();
++  assert(the_new_class->member_names() == NULL, "");
++  the_new_class->set_member_names(mnt);
++  the_old_class->set_member_names(NULL);
++
++  // FIXME: should we add field MemberName's in this list and process all of them here?
++//  if (mnt != NULL) {
++//    for (int i = 0; i < mnt->length(); i++) {
++//      oop mem_name = mnt->get_member_name(i);
++//      if (mem_name != NULL) {
++//        Method* method = (Method*) java_lang_invoke_MemberName::vmtarget(mem_name);
++//
++//        // Replace the method with matching one from the new class
++//        Method* new_method = the_new_class->find_method(method->name(), method->signature());
++//        java_lang_invoke_MemberName::set_vmtarget(mem_name, new_method);
++//      }
++//    }
++//  }
++
++#ifdef ASSERT
++
++//  Klass* 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();
++
++//  Klass* 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()->new_version() == the_new_class(), "Must equal");
++
++  for (int i=0; i<the_new_class->methods()->length(); i++) {
++    assert((the_new_class->methods()->at(i))->method_holder() == the_new_class(), "method holder must match!");
++  }
++
++  // FIXME:
++  //_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(), THREAD);
++
++}
++
++
++void VM_EnhancedRedefineClasses::check_methods_and_mark_as_obsolete(BitMap *emcp_methods, int * emcp_method_count_p) {
++  RC_TRACE(0x00000100, ("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) {
++      Method* old_method = _old_methods->at(_matching_old_methods[j]);
++      Method* new_method = _new_methods->at(_matching_new_methods[j]);
++      Method* old_array_method;
++
++    // Maintain an old_index into the _old_methods array by skipping
++    // deleted methods
++    while ((old_array_method = _old_methods->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(0x00000100, ("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(0x00000100, ("Checking breakpoint: %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(0x00000100, ("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(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) {
++      Method* old_method = _old_methods->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(0x00000100, ("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(0x00000100, ("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_EnhancedRedefineClasses::increment_class_counter(Klass* klass, TRAPS) {
++  oop class_mirror = klass->java_mirror();
++  int new_count = java_lang_Class::classRedefinedCount(class_mirror) + 1;
++  java_lang_Class::set_classRedefinedCount(class_mirror, new_count);
++  RC_TRACE(0x00000008, ("updated count for class=%s to %d", klass->external_name(), new_count));
++}
++
++#ifndef PRODUCT
++void VM_EnhancedRedefineClasses::check_class(Klass* k_oop, TRAPS) {
++  Klass *k = k_oop;
++  if (k->oop_is_instance()) {
++    HandleMark hm(THREAD);
++    InstanceKlass *ik = (InstanceKlass *) k;
++    assert(ik->is_newest_version(), "must be latest version in system dictionary");
++
++    if (ik->vtable_length() > 0) {
++      ResourceMark rm(THREAD);
++      assert(ik->vtable()->check_no_old_or_obsolete_entries(), "old method found");
++      ik->vtable()->verify(tty, true);
++    }
++  }
++}
++
++#endif
++
++static bool match_second(void* value, Pair<Klass*, Klass*> elem) {
++  return elem.second == value;
++}
++
++jvmtiError VM_EnhancedRedefineClasses::do_topological_class_sorting( const jvmtiClassDefinition *class_defs, int class_count, TRAPS) {
++  ResourceMark mark(THREAD);
++  GrowableArray<Pair<Klass*, Klass*> > links;
++
++  for (int i=0; i<class_count; i++) {
++
++    oop mirror = JNIHandles::resolve_non_null(class_defs[i].klass);
++    instanceKlassHandle the_class(THREAD, java_lang_Class::as_Klass(mirror));
++    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_EnhancedRedefineClasses__");
++    ClassFileParser cfp(&st);
++
++
++
++    TempNewSymbol parsed_name;
++    GrowableArray<Symbol*>* super_symbols = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<Symbol*>(0, true);
++    cfp.parseClassFile(the_class->name(),
++                       the_class->class_loader_data(),
++                       protection_domain,
++                       the_class, KlassHandle(),
++                       NULL,
++                       super_symbols,
++                       parsed_name,
++                       false,
++                       THREAD);
++
++    for (int j = 0; j < super_symbols->length(); j++) {
++      Symbol* sym = super_symbols->at(j);
++      Klass* super_klass = SystemDictionary::resolve_or_null(sym, the_class_loader, protection_domain, THREAD);
++      if (super_klass != NULL) {
++        instanceKlassHandle the_super_class(THREAD, super_klass);
++        if (_affected_klasses->contains(the_super_class)) {
++          links.append(Pair<Klass*, Klass*>(super_klass, the_class()));
++        }
++      }
++    }
++    delete super_symbols;
++
++    assert(the_class->check_redefinition_flag(Klass::MarkedAsAffected), "");
++    the_class->clear_redefinition_flag(Klass::MarkedAsAffected);
++  }
++
++  for (int i=0; i < _affected_klasses->length(); i++) {
++    instanceKlassHandle klass = _affected_klasses->at(i);
++
++    if (klass->check_redefinition_flag(Klass::MarkedAsAffected)) {
++      klass->clear_redefinition_flag(Klass::MarkedAsAffected);
++      Klass* superKlass = klass->super();
++      if (_affected_klasses->contains(superKlass)) {
++        links.append(Pair<Klass*, Klass*>(superKlass, klass()));
++      }
++
++      Array<Klass*>* superInterfaces = klass->local_interfaces();
++      for (int j=0; j<superInterfaces->length(); j++) {
++        Klass* interfaceKlass = superInterfaces->at(j);
++        if (_affected_klasses->contains(interfaceKlass)) {
++          links.append(Pair<Klass*, Klass*>(interfaceKlass, klass()));
++        }
++      }
++    }
++  }
++
++  for (int i = 0; i < _affected_klasses->length(); i++) {
++    int j;
++    for (j = i; j < _affected_klasses->length(); j++) {
++      // Search for node with no incoming edges
++      Klass* oop = _affected_klasses->at(j)();
++      int k = links.find(oop, match_second);
++      if (k == -1) break;
++    }
++    if (j == _affected_klasses->length()) {
++      return JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION;
++    }
++
++    // Remove all links from this node
++    Klass* oop = _affected_klasses->at(j)();
++    int k = 0;
++    while (k < links.length()) {
++      if (links.adr_at(k)->first == oop) {
++        links.delete_at(k);
++      } else {
++        k++;
++      }
++    }
++
++    // Swap node
++    instanceKlassHandle tmp = _affected_klasses->at(j);
++    _affected_klasses->at_put(j, _affected_klasses->at(i));
++    _affected_klasses->at_put(i, tmp);
++  }
++
++  return JVMTI_ERROR_NONE;
++}
++
++// 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
++// removed.
++// It expects only to be used during the VM_EnhancedRedefineClasses op (a safepoint).
++//
++// This class is used after the new methods have been installed in "the_class".
++//
++// So, for example, the following must be handled.  Where 'm' is a method and
++// a number followed by an underscore is a prefix.
++//
++//                                      Old Name    New Name
++// Simple transfer to new method        m       ->  m
++// Add prefix                           m       ->  1_m
++// Remove prefix                        1_m     ->  m
++// Simultaneous add of prefixes         m       ->  3_2_1_m
++// Simultaneous removal of prefixes     3_2_1_m ->  m
++// Simultaneous add and remove          1_m     ->  2_m
++// Same, caused by prefix removal only  3_2_1_m ->  3_2_m
++//
++class TransferNativeFunctionRegistration {
++ private:
++  instanceKlassHandle the_class;
++  int prefix_count;
++  char** prefixes;
++
++  // Recursively search the binary tree of possibly prefixed method names.
++  // Iteration could be used if all agents were well behaved. Full tree walk is
++  // more resilent to agents not cleaning up intermediate methods.
++  // Branch at each depth in the binary tree is:
++  //    (1) without the prefix.
++  //    (2) with the prefix.
++  // where 'prefix' is the prefix at that 'depth' (first prefix, second prefix,...)
++  Method* search_prefix_name_space(int depth, char* name_str, size_t name_len,
++                                     Symbol* signature) {
++      Symbol* name_symbol = SymbolTable::probe(name_str, (int)name_len);
++    if (name_symbol != NULL) {
++        Method* method = the_class()->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;
++        }
++        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 the method name with old prefixes stripped away.
++  char* method_name_without_prefixes(Method* method) {
++    Symbol* name = method->name();
++    char* name_str = name->as_utf8();
++
++    // Old prefixing may be defunct, strip prefixes, if any.
++    for (int i = prefix_count-1; i >= 0; i--) {
++      char* prefix = prefixes[i];
++      size_t prefix_len = strlen(prefix);
++      if (strncmp(prefix, name_str, prefix_len) == 0) {
++        name_str += prefix_len;
++      }
++    }
++    return name_str;
++  }
++
++  // Strip any prefixes off the old native method, then try to find a
++  // (possibly prefixed) new native that matches it.
++  Method* strip_and_search_for_new_native(Method* method) {
++    ResourceMark rm;
++    char* name_str = method_name_without_prefixes(method);
++    return search_prefix_name_space(0, name_str, strlen(name_str),
++                                    method->signature());
++  }
++
++ public:
++
++  // Construct a native method transfer processor for this class.
++  TransferNativeFunctionRegistration(instanceKlassHandle _the_class) {
++    assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
++
++    the_class = _the_class;
++    prefixes = JvmtiExport::get_all_native_method_prefixes(&prefix_count);
++  }
++
++  // Attempt to transfer any of the old or deleted methods that are native
++  void transfer_registrations(instanceKlassHandle old_klass, int* old_methods, int methods_length) {
++    for (int j = 0; j < methods_length; j++) {
++      Method* old_method = old_klass->methods()->at(old_methods[j]);
++
++      if (old_method->is_native() && old_method->has_native_function()) {
++        Method* new_method = strip_and_search_for_new_native(old_method);
++        if (new_method != NULL) {
++          // Actually set the native function in the new method.
++          // Redefine does not send events (except CFLH), certainly not this
++          // behind the scenes re-registration.
++          new_method->set_native_function(old_method->native_function(),
++            !Method::native_bind_event_is_interesting);
++        }
++      }
++    }
++  }
++};
++
++// Don't lose the association between a native method and its JNI function.
++void VM_EnhancedRedefineClasses::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);
++}
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/prims/jvmtiRedefineClasses2.hpp
+--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
++++ b/src/share/vm/prims/jvmtiRedefineClasses2.hpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -0,0 +1,159 @@
++/*
++ * 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.
++ *
++ */
++
++#ifndef SHARE_VM_PRIMS_JVMTIENHANCEDREDEFINECLASSES_HPP
++#define SHARE_VM_PRIMS_JVMTIENHANCEDREDEFINECLASSES_HPP
++
++#include "jvmtifiles/jvmtiEnv.hpp"
++#include "memory/oopFactory.hpp"
++#include "memory/resourceArea.hpp"
++#include "oops/objArrayKlass.hpp"
++#include "oops/objArrayOop.hpp"
++#include "oops/fieldStreams.hpp"
++#include "prims/jvmtiRedefineClassesTrace.hpp"
++#include "gc_implementation/shared/vmGCOperations.hpp"
++
++// New version that allows arbitrary changes to already loaded classes.
++class VM_EnhancedRedefineClasses: public VM_GC_Operation {
++ private:
++
++  // These static fields are needed by SystemDictionary::classes_do()
++  // facility and the adjust_cpool_cache_and_vtable() helper:
++  static Array<Method*>* _old_methods;
++  static Array<Method*>* _new_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 int             _revision_number;
++
++  static GrowableArray<instanceKlassHandle>* _affected_klasses;
++
++  // The instance fields are used to pass information from
++  // doit_prologue() to doit() and doit_epilogue().
++  jint                        _class_count;
++  const jvmtiClassDefinition *_class_defs;  // ptr to _class_count defs
++
++  // This operation is used by both RedefineClasses and
++  // RetransformClasses.  Indicate which.
++  JvmtiClassLoadKind          _class_load_kind;
++
++  GrowableArray<instanceKlassHandle>* _new_classes;
++  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_total;
++  elapsedTimer _timer_prologue;
++  elapsedTimer _timer_class_linking;
++  elapsedTimer _timer_class_loading;
++  elapsedTimer _timer_prepare_redefinition;
++  elapsedTimer _timer_heap_iteration;
++  elapsedTimer _timer_redefinition;
++  elapsedTimer _timer_vm_op_epilogue;
++
++  jvmtiError find_sorted_affected_classes( );
++  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);
++
++  // 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();
++
++  // Change jmethodIDs to point to the new methods
++  void update_jmethod_ids();
++
++  static void add_affected_klasses( Klass* obj );
++
++  static jvmtiError do_topological_class_sorting(const jvmtiClassDefinition *class_definitions, int class_count, TRAPS);
++
++  // Install the redefinition of a class
++  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(Klass* klass, TRAPS);
++
++
++  void flush_dependent_code(instanceKlassHandle k_h, TRAPS);
++
++  static void check_class(Klass* k_oop,/* oop initiating_loader,*/ TRAPS) PRODUCT_RETURN;
++
++  static void unpatch_bytecode(Method* method);
++
++#ifdef ASSERT
++  static void verify_classes(Klass* k_oop, oop initiating_loader, TRAPS);
++#endif
++
++  int calculate_redefinition_flags(instanceKlassHandle new_version);
++  void calculate_instance_update_information(Klass* new_version);
++  void check_methods_and_mark_as_obsolete(BitMap *emcp_methods, int * emcp_method_count_p);
++  static void mark_as_scavengable(nmethod* nm);
++
++  bool check_arguments();
++  jvmtiError check_arguments_error();
++
++  class ClearCpoolCacheAndUnpatch : public KlassClosure {
++    Thread* _thread;
++   public:
++    ClearCpoolCacheAndUnpatch(Thread* t) : _thread(t) {}
++    void do_klass(Klass* k);
++  };
++
++ public:
++  VM_EnhancedRedefineClasses(jint class_count, const jvmtiClassDefinition *class_defs, JvmtiClassLoadKind class_load_kind);
++  virtual ~VM_EnhancedRedefineClasses();
++
++  bool doit_prologue();
++  void doit();
++  void doit_epilogue();
++  void rollback();
++
++  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;  }
++
++  // Modifiable test must be shared between IsModifiableClass query
++  // and redefine implementation
++  static bool is_modifiable_class(oop klass_mirror);
++
++  // Utility methods for transferring field access flags
++
++  static void transfer_special_access_flags(JavaFieldStream *from, JavaFieldStream *to);
++  static void transfer_special_access_flags(fieldDescriptor *from, fieldDescriptor *to);
++
++  void transfer_old_native_function_registrations(instanceKlassHandle the_class);
++
++  static void swap_marks(oop first, oop second);
++};
++
++#endif // SHARE_VM_PRIMS_JVMTIENHANCEDREDEFINECLASSES_HPP
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/runtime/mutexLocker.cpp
+--- a/src/share/vm/runtime/mutexLocker.cpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/runtime/mutexLocker.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -259,7 +259,7 @@
+   }
+   def(Heap_lock                    , Monitor, nonleaf+1,   false);
+   def(JfieldIdCreation_lock        , Mutex  , nonleaf+1,   true ); // jfieldID, Used in VM_Operation
+-  def(MemberNameTable_lock         , Mutex  , nonleaf+1,   false); // Used to protect MemberNameTable
++  def(MemberNameTable_lock         , Mutex  , nonleaf+1,   true); // Used to protect MemberNameTable
+ 
+   def(CompiledIC_lock              , Mutex  , nonleaf+2,   false); // locks VtableStubs_lock, InlineCacheBuffer_lock
+   def(CompileTaskAlloc_lock        , Mutex  , nonleaf+2,   true );
+diff -r da0f21b5d65d -r 02a2c97b5699 src/share/vm/runtime/reflection.cpp
+--- a/src/share/vm/runtime/reflection.cpp	Sat Jan 19 03:37:32 2019 +0100
++++ b/src/share/vm/runtime/reflection.cpp	Sat Jan 19 03:39:20 2019 +0100
+@@ -520,6 +520,12 @@
+                                      AccessFlags access,
+                                      bool classloader_only,
+                                      bool protected_restriction) {
++
++  // (DCEVM) Decide accessibility based on active version
++  if (current_class != NULL) {
++    current_class = current_class->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.
diff --git a/hotspot/.hg/patches/series b/hotspot/.hg/patches/series
index ea54f85b..2e5e8d7c 100644
--- a/hotspot/.hg/patches/series
+++ b/hotspot/.hg/patches/series
@@ -4,19 +4,20 @@ distro-name.patch
 # Add AllowEnhancedRedefinition argument
 arguments-java8.patch #+light-jdk8u5-b13 #+light-jdk8u20-b22
 arguments-java8u31.patch #+light-jdk8u31-b13
-arguments-java8u40.patch #+light-jdk8u40-b25 #+light-jdk8u45-b14 #+light-jdk8u51-b16 #+light-jdk8u66-b17 #+light-jdk8u74-b02 #+light-jdk8u92-b14 #+light-jdk8u102-b31 #+light-jdk8u111-b14 #+light-jdk8u112-b16 #+light-jdk8u144-b01 #+light-jdk8u152-b16 #+light-jdk8u172-b11 #+light-jdk8u181-b13
+arguments-java8u40.patch #+light-jdk8u40-b25 #+light-jdk8u45-b14 #+light-jdk8u51-b16 #+light-jdk8u66-b17 #+light-jdk8u74-b02 #+light-jdk8u92-b14 #+light-jdk8u102-b31 #+light-jdk8u111-b14 #+light-jdk8u112-b16 #+light-jdk8u144-b01 #+light-jdk8u152-b16 #+light-jdk8u172-b11 #+light-jdk8u181-b13 #+light-jdk8u201-b09 #+light-jdk8u202-b08
 
 # GC changes to allow modifying instances during redefinition run
 gc-java8.patch #+light-jdk8u5-b13 #+light-jdk8u20-b22 #+light-jdk8u31-b13
-gc-java8u40.patch #+light-jdk8u40-b25 #+light-jdk8u45-b14 #+light-jdk8u51-b16 #+light-jdk8u66-b17 #+light-jdk8u74-b02 #+light-jdk8u92-b14 #+light-jdk8u102-b31 #+light-jdk8u111-b14 #+light-jdk8u112-b16 #+light-jdk8u144-b01 #+light-jdk8u152-b16 #+light-jdk8u172-b11 #+light-jdk8u181-b13
+gc-java8u40.patch #+light-jdk8u40-b25 #+light-jdk8u45-b14 #+light-jdk8u51-b16 #+light-jdk8u66-b17 #+light-jdk8u74-b02 #+light-jdk8u92-b14 #+light-jdk8u102-b31 #+light-jdk8u111-b14 #+light-jdk8u112-b16 #+light-jdk8u144-b01 #+light-jdk8u152-b16 #+light-jdk8u172-b11 #+light-jdk8u181-b13 #+light-jdk8u201-b09 #+light-jdk8u202-b08
 
 # Add support for certain DMH implementations
 dmh-field-accessors-java8.patch #+light-jdk8u5-b13 #+light-jdk8u20-b22 #+light-jdk8u31-b13
 dmh-field-accessors-java8u40.patch #+light-jdk8u40-b25 #+light-jdk8u45-b14 #+light-jdk8u51-b16 #+light-jdk8u66-b17 #+light-jdk8u74-b02 #+light-jdk8u92-b14 #+light-jdk8u102-b31 #+light-jdk8u111-b14 #+light-jdk8u112-b16 #+light-jdk8u144-b01 #+light-jdk8u152-b16
 dmh-field-accessors-java8u172.patch #+light-jdk8u172-b11 #+light-jdk8u181-b13
+dmh-field-accessors-java8u201.patch #+light-jdk8u201-b09 #+light-jdk8u202-b08
 
 # Stub JVM_SetVmMemoryPressure function
-JVM_SetVmMemoryPressure.patch #+light-jdk8u45-b14 #+light-jdk8u51-b16 #+light-jdk8u66-b17 #+light-jdk8u74-b02 #+light-jdk8u92-b14 #+light-jdk8u102-b31 #+light-jdk8u111-b14 #+light-jdk8u112-b16 #+light-jdk8u144-b01 #+light-jdk8u152-b16 #+light-jdk8u172-b11 #+light-jdk8u181-b13
+JVM_SetVmMemoryPressure.patch #+light-jdk8u45-b14 #+light-jdk8u51-b16 #+light-jdk8u66-b17 #+light-jdk8u74-b02 #+light-jdk8u92-b14 #+light-jdk8u102-b31 #+light-jdk8u111-b14 #+light-jdk8u112-b16 #+light-jdk8u144-b01 #+light-jdk8u152-b16 #+light-jdk8u172-b11 #+light-jdk8u181-b13 #+light-jdk8u201-b09 #+light-jdk8u202-b08
 
 # Rest of the changes
 full-jdk7u11-b21.patch  #+full-jdk7u11-b21
@@ -53,10 +54,11 @@ light-jdk8u92-b14.patch #+light-jdk8u92-b14 #+light-jdk8u102-b31 #+light-jdk8u11
 light-jdk8u112-b16.patch #+light-jdk8u112-b16 #+light-jdk8u144-b01
 light-jdk8u152-b16.patch #+light-jdk8u152-b16 #+light-jdk8u172-b11
 light-jdk8u181-b13.patch #+light-jdk8u181-b13
+light-jdk8u201-b09.patch #+light-jdk8u201-b09 #+light-jdk8u202-b08
 jvmti-getLoadedClasses-java8.patch #+light-jdk8u112-b16 #+light-jdk8u144-b01 #+light-jdk8u152-b16 #+light-jdk8u172-b11
 jvmti-lockRedefine-java8.patch #+light-jdk8u144-b01delete
 light-jdk8u20-deopt-cp.patch #+light-jdk8u20-b22 #+light-jdk8u31-b13 #+light-jdk8u40-b25 #+light-jdk8u45-b14 #+light-jdk8u51-b16
-light-jdk8u66-b17-deopt-cp.patch #+light-jdk8u66-b17 #+light-jdk8u74-b02 #+light-jdk8u92-b14 #+light-jdk8u102-b31 #+light-jdk8u111-b14 #+light-jdk8u112-b16 #+light-jdk8u144-b01 #+light-jdk8u152-b16 #+light-jdk8u172-b11 #+light-jdk8u181-b13
-dont-clear-f1.patch #+light-jdk8u74-b02 #+light-jdk8u92-b14 #+light-jdk8u102-b31 #+light-jdk8u111-b14 #+light-jdk8u112-b16 #+light-jdk8u144-b01 #+light-jdk8u152-b16 #+light-jdk8u172-b11 #+light-jdk8u181-b13
-light-updateClassRedefinedCount-java8.patch #+light-jdk8u112-b16 #+light-jdk8u144-b01 #+light-jdk8u152-b16 #+light-jdk8u172-b11 #+light-jdk8u181-b13
-orig-meth-ids-revert-jdk8u152.patch #+light-jdk8u152-b16 #+light-jdk8u172-b11 #+light-jdk8u181-b13
+light-jdk8u66-b17-deopt-cp.patch #+light-jdk8u66-b17 #+light-jdk8u74-b02 #+light-jdk8u92-b14 #+light-jdk8u102-b31 #+light-jdk8u111-b14 #+light-jdk8u112-b16 #+light-jdk8u144-b01 #+light-jdk8u152-b16 #+light-jdk8u172-b11 #+light-jdk8u181-b13 #+light-jdk8u201-b09 #+light-jdk8u202-b08
+dont-clear-f1.patch #+light-jdk8u74-b02 #+light-jdk8u92-b14 #+light-jdk8u102-b31 #+light-jdk8u111-b14 #+light-jdk8u112-b16 #+light-jdk8u144-b01 #+light-jdk8u152-b16 #+light-jdk8u172-b11 #+light-jdk8u181-b13 #+light-jdk8u201-b09 #+light-jdk8u202-b08
+light-updateClassRedefinedCount-java8.patch #+light-jdk8u112-b16 #+light-jdk8u144-b01 #+light-jdk8u152-b16 #+light-jdk8u172-b11 #+light-jdk8u181-b13 #+light-jdk8u201-b09 #+light-jdk8u202-b08
+orig-meth-ids-revert-jdk8u152.patch #+light-jdk8u152-b16 #+light-jdk8u172-b11 #+light-jdk8u181-b13 #+light-jdk8u201-b09 #+light-jdk8u202-b08