fpOffset+STACKFRAME_METHOD_ID_OFFSET);
fpOffset.add(STACKFRAME_METHOD_ID_OFFSET));
  private static void walkOnStack(byte[] stack, int fpOffset) {    int cmid = STACKFRAME_SENTINEL_FP.toInt();    do {      cmid = VM_Magic.getIntAtOffset(stack,                                        fpOffset+STACKFRAME_METHOD_ID_OFFSET);      if (cmid == INVISIBLE_METHOD_ID) {        VM.sysWriteln(" invisible method ");      } else {        VM_CompiledMethod cm = VM_CompiledMethods.getCompiledMethod(cmid);        VM.sysWriteln(cm.getMethod().toString());      }      VM.disableGC();      Address callerfp = VM_Magic.objectAsAddress(stack).add(                               fpOffset+STACKFRAME_FRAME_POINTER_OFFSET).loadAddress();      fpOffset = callerfp.diff(VM_Magic.objectAsAddress(stack)).toInt();      VM.enableGC();    } while (cmid != STACKFRAME_SENTINEL_FP.toInt());  }