如何使用ASM获取初始化对象的位置？

import org.objectweb.asm.*;
import java.io.IOException;

public class MyClassVisitor extends ClassVisitor {

    public MyClassVisitor() {
        super(Opcodes.ASM5);
    }

    @Override
    public MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions) {
        if (name.equals("<init>")) {
            return new MethodVisitor(Opcodes.ASM5) {
                @Override
                public void visitVarInsn(int opcode, int var) {
                    if (opcode == Opcodes.ALOAD && var == 0) {
                        System.out.println("Initialization object position: " + var);
                    }
                    super.visitVarInsn(opcode, var);
                }
            };
        }
        return super.visitMethod(access, name, desc, signature, exceptions);
    }

    public static void main(String[] args) throws IOException {
        ClassReader cr = new ClassReader("com.example.MyClass");
        MyClassVisitor cv = new MyClassVisitor();
        cr.accept(cv, ClassReader.EXPAND_FRAMES);
    }
}