From: LayHool <23442547+layhool@users.noreply.github.com>
Date: Thu, 16 Mar 2023 03:01:40 +0000 (+0800)
Subject: Fix issue in no-standard [new] instruction replace
X-Git-Tag: rel_3_30_0_ga~5^2
X-Git-Url: https://source.dussan.org/?a=commitdiff_plain;h=refs%2Fpull%2F448%2Fhead;p=javassist.git

Fix issue in no-standard [new] instruction replace

A standard *new* construct bytecode will generate like:

```
new okhttp3/OkHttpClient
dup
invokespecial okhttp3/OkHttpClient <init> ()V
astore 1
```

but a few part of compiler will generate no-standard bytecode like:

```
new okhttp3/OkHttpClient
dup
astore 1
invokespecial okhttp3/OkHttpClient <init> ()V
```
which will cause javassist build stack error.

This commit will fix it
---

diff --git a/src/main/javassist/expr/NewExpr.java b/src/main/javassist/expr/NewExpr.java
index 3171fc3f..ee065167 100644
--- a/src/main/javassist/expr/NewExpr.java
+++ b/src/main/javassist/expr/NewExpr.java
@@ -193,6 +193,14 @@ public class NewExpr extends Expr {
          */
         int codeSize = canReplace();
         int end = pos + codeSize;
+        //check isStoreBeforeInit ,such as :  new xx/xx ; dup;[astoreN];invokespecial xx/xx;
+        int beforeStoreOp = 0;
+        int preOp = iterator.byteAt(currentPos - 1);
+        if (iterator.byteAt(newPos + 3) == Opcode.DUP
+                && (preOp >= Opcode.ASTORE_0
+                && preOp <= Opcode.ASTORE_3) && currentPos - newPos == 5) {
+            beforeStoreOp = preOp;
+        }
         for (int i = pos; i < end; ++i)
             iterator.writeByte(NOP, i);
 
@@ -230,7 +238,12 @@ public class NewExpr extends Expr {
             if (codeSize > 3)   // if the original code includes DUP.
                 bytecode.addAload(retVar);
 
-            replace0(pos, bytecode, bytecodeSize);
+            if (beforeStoreOp >= Opcode.ASTORE_0) {
+                bytecode.addOpcode(beforeStoreOp);
+                replace0(pos - 1, bytecode, bytecodeSize + 1);
+            } else {
+                replace0(pos, bytecode, bytecodeSize);
+            }
         }
         catch (CompileError e) { throw new CannotCompileException(e); }
         catch (NotFoundException e) { throw new CannotCompileException(e); }