void vm_exit(int code) {

  {- -------------------------------------------
  (1) もし ThreadLocalStorage からカレントスレッドが取得できない場合
      (<= これは何か致命的な問題が生じている場合), 
      vm_direct_exit() ですぐに終了.
      ---------------------------------------- -}

      Thread* thread = ThreadLocalStorage::is_initialized() ?
        ThreadLocalStorage::get_thread_slow() : NULL;
      if (thread == NULL) {
        // we have serious problems -- just exit
        vm_direct_exit(code);
      }

  {- -------------------------------------------
  (1) まだ VMThread が生きていれば VM_Exit を実行する.
      (通常はここで終了.
       もし VMThread が何か失敗すれば, その後に vm_direct_exit() を実行して終了することになるらしい)
      ---------------------------------------- -}

      if (VMThread::vm_thread() != NULL) {
        // Fire off a VM_Exit operation to bring VM to a safepoint and exit
        VM_Exit op(code);
        if (thread->is_Java_thread())
          ((JavaThread*)thread)->set_thread_state(_thread_in_vm);
        VMThread::execute(&op);
        // should never reach here; but in case something wrong with VM Thread.
        vm_direct_exit(code);

  {- -------------------------------------------
  (1) VMThread が生きていなければ vm_direct_exit() を実行するだけ.
      ---------------------------------------- -}

      } else {
        // VM thread is gone, just exit
        vm_direct_exit(code);
      }
      ShouldNotReachHere();