private static void walkOnStack(byte[] stack, int fpOffset) {
private static void walkOnStack(byte[] stack, Offset fpOffset) {
  private static void walkOnStack(byte[] stack, int fpOffset) {    VM.disableGC();        Address fp = VM_Magic.objectAsAddress(stack).add(fpOffset);            while (VM_Magic.getCallerFramePointer(fp).NE(STACKFRAME_SENTINEL_FP) ){      int cmid = VM_Magic.getCompiledMethodID(fp);            if (cmid == INVISIBLE_METHOD_ID) {        VM.sysWriteln(" invisible method ");      } else {        VM_CompiledMethod cm = VM_CompiledMethods.getCompiledMethod(cmid);        fpOffset = fp.diff(VM_Magic.objectAsAddress(stack)).toInt();        VM.enableGC();                VM.sysWriteln(cm.getMethod().toString());                        VM.disableGC();        fp = VM_Magic.objectAsAddress(stack).add(fpOffset);        if (cm.getMethod().getDeclaringClass().isBridgeFromNative()) {          fp = VM_Runtime.unwindNativeStackFrame(fp);        }      }            fp = VM_Magic.getCallerFramePointer(fp);    }        VM.enableGC();  }