Re: Re: Re: Re: add code to existing method code

----- Original Message ----- 
From: "Eugene Kuleshov" <[email protected]>
To: <[email protected]>
Sent: Sunday, September 26, 2010 3:00 PM
Subject: [asm] Re: Re: Re: add code to existing method code


> Rémi Forax wrote:
>>>  Your assumption is correct. The order of visit calls is documented
>>> at
>>> http://asm.ow2.org/asm33/javadoc/user/org/objectweb/asm/MethodVisitor.html
>>>
>> And if you want to put additional code, the best is to trap all return
>> instructions
>> in visitInsn.
>>
>> public void visitInsn(int opcode) {
>>   // trick all return opcodes are between IRETURN and RETURN
>>   if (opcode >= IRETURN && opcode <= RETURN) {
>>      // don't forget that the return value is already on top of the stack
>>      ...
>>   }
>>   super.visitInsn(opcode);
>> }
>  Good point Remi. We there is also an AdviceAdapter that takes care of
> that:
>
> http://asm.ow2.org/asm33/javadoc/user/org/objectweb/asm/commons/AdviceAdapter.html
>
>  regards,
>  Eugene
>

Thank you for the reply.

My goal is to notify exit from method in all the cases
I already added call to notify before all returns instruction as you 
describe it.
But I also want to notify in case of exception, so I enhance the code adding 
a try { } finaly{ notification } like this:

 @Override
 public void visitCode() {
  methodVisitor.visitCode();
  if (addEnable && !INIT_METHOD_NAME.equals(methodName)) {
   /*
    * add call to intercept$JOAFIP$ to begin of method code (not in
    * constructor)
    */
   final Label label0 = new Label();
   label1 = new Label();
   methodVisitor.visitTryCatchBlock(label0, label1, label1, null);
   methodVisitor.visitLabel(label0);
   methodVisitor.visitVarInsn(ALOAD, 0);
   methodVisitor.visitMethodInsn(
   /**/INVOKESTATIC, STATIC_PROXY_CALL_BACK,
   /**/"intercept$JOAFIP$", LJAVA_LANG_OBJECT_V_DESC);
  }
 }

and

 @Override
 public void visitMaxs(final int maxStack, final int maxLocals) {
  if (addEnable && !INIT_METHOD_NAME.equals(methodName)) {
   methodVisitor.visitLabel(label1);
   methodVisitor.visitFrame(Opcodes.F_SAME1, 0, null, 1,
     new Object[] { "java/lang/Throwable" });
   methodVisitor.visitVarInsn(ASTORE, maxLocals - 1);
   // this
   methodVisitor.visitVarInsn(ALOAD, 0);
   methodVisitor.visitMethodInsn(
   /**/INVOKESTATIC, STATIC_PROXY_CALL_BACK,
   /**/"methodEnd$JOAFIP$", LJAVA_LANG_OBJECT_V_DESC);
   methodVisitor.visitVarInsn(ALOAD, maxLocals - 1);
   methodVisitor.visitInsn(ATHROW);
  }
 .......
 }

Best regards

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