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copied!<p>Thanks again to Mike and ruediste for their comments.</p> <p>Mike was right: My problem was that I tried passing a reference as a method call argument right after it was created by NEW but before its constructor has been called. The JVM specification clearly states that such a behavior is forbidden: "The verifier rejects code that uses the new object before it has been initialized [...]" (see <a href="http://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.10.2.4" rel="nofollow">http://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.10.2.4</a>)</p> <p>However, the instruction sequence of creating and initializing a new object leaves my desired object on top of the operand stack where it can easily be obtained :)</p> <p>In the end, I blew up my code bit for the INVOKESPECIAL handling:</p> <pre><code>if (opcode == INVOKESPECIAL) { // Invoke constructors and private methods // Ignore initialization of java/lang/Object if (name.equals("<init>") && owner.equals("java/lang/Object")) { super.visitMethodInsn(opcode, owner, name, desc); return; } if (methodName.equals("<clinit>")) { if (name.equals("<clinit>")) { // call to a static initializer from within a static initializer // there is no object reference! super.visitMethodInsn(opcode, owner, name, desc); } else if (name.equals("<init>")) { // call to a constructor from within a static initializer super.visitMethodInsn(opcode, owner, name, desc); // object reference is initialized and on stack now -> obtain it via DUP } else { // call to a private method from within a static initializer // no this-reference in static initializer! super.visitMethodInsn(opcode, owner, name, desc); } } else if (methodName.equals("<init>")) { if (name.equals("<clinit>")) { // call to a static initializer from within a constructor // there is no object reference! super.visitMethodInsn(opcode, owner, name, desc); } else if (name.equals("<init>")) { // call to a constructor from within a constructor super.visitMethodInsn(opcode, owner, name, desc); // if this constructor call is not an invocation of the super constructor: obtain object reference via DUP } else { // call to a private method from within a constructor // object reference is the this-reference (at local variable 0) super.visitMethodInsn(opcode, owner, name, desc); } } else { if (name.equals("<clinit>")) { // call to a static initializer from within some method // there is no object reference! super.visitMethodInsn(opcode, owner, name, desc); } else if (name.equals("<init>")) { // call to a constructor from within some method super.visitMethodInsn(opcode, owner, name, desc); // obtain object reference via DUP } else { // call to a private method from within some method // if the private method is called within some NON-STATIC method: object reference is the this-reference (at local variable 0) // if the private method is called within some NON-STATIC method: there is no object reference! super.visitMethodInsn(opcode, owner, name, desc); } } } </code></pre> <p>Possibly this helps someone who's trying to do similar stuff :)</p>

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