Problem reloading a local variable in ASM

Hi all,

I have a weird problem with accessing a previously created local variable
through ASM and I hope you expertise can help me.

I am trying to retrieve the name of a class implementing a Java interface
and then using this name as a key in a data structure to retrieve some code
metrics about the class. Here is what I have done:

    public void visitMethodInsn(int opcode, String owner, String name,
String desc) {

       int methodOwner = _lvs.newLocal(Type.getType("Ljava/lang/String;"));

       if (opcode == Opcodes.INVOKEINTERFACE) {

            // pop the operand stack to get to the object whose method is
being called

            int callingObj = _lvs.newLocal(Type.getType(Object.class));
            this.visitVarInsn(Opcodes.ASTORE, callingObj);
            this.visitVarInsn(Opcodes.ALOAD, callingObj);
            this.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/lang/Object",
"getClass", "()Ljava/lang/Class;");
            this.visitMethodInsn(Opcodes.INVOKEVIRTUAL, "java/lang/Class",
"getName", "()Ljava/lang/String;");
            this.visitVarInsn(Opcodes.ASTORE, methodOwner);
            this.visitVarInsn(Opcodes.ALOAD, callingObj);

            /// (1)
            /// some code using the methodOwner ....
            /// something like the following
            /// this.visitVarInsn(Opcodes.ALOAD, methodOwner);

            /// reconstruct the operand stack for the method to be invoked
       }

       super.visitMethodInsn(opcode, owner, name, desc);

       if (opcode == Opcodes.INVOKEINTERFACE) {
            /// (2)
            /// some more code using the methodOwner  .....
            ///
            /// this.visitVarInsn(Opcodes.ALOAD, methodOwner);
       }
    }

If I comment out code snippets in block (2) from the code above, it works.
However when I try to access "methodOwner" in block (2), I receive the
following verification error indicating that the string object is gone
missing. I can't understand why.

      org.objectweb.asm.tree.analysis.AnalyzerException: Error at
instruction 813: Expected an object reference, but found .

Since calling "super.visitMethodInsn(opcode, owner, name, desc);" pops the
object whose interface method is called, I can't get a reference to it
again. I tried keeping a second copy of the object in another variable but
same problem occurs.

I wonder if you have any clue on what is wrong here and if you can give me
some advice.

thanks very much for your help,
nemo

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