// Helper routine used in several places

int JvmtiThreadState::count_frames() {

  {- -------------------------------------------
  (1) (デバッグ用の処理) (#ifdef ASSERT 時にのみ実行)
      ---------------------------------------- -}

    #ifdef ASSERT
      uint32_t debug_bits = 0;
    #endif

  {- -------------------------------------------
  (1) (assert)
      ---------------------------------------- -}

      assert(SafepointSynchronize::is_at_safepoint() ||
             JvmtiEnv::is_thread_fully_suspended(get_thread(), false, &debug_bits),
             "at safepoint or must be suspended");

  {- -------------------------------------------
  (1) Java フレームがなければ 0 をリターン
      ---------------------------------------- -}

      if (!get_thread()->has_last_Java_frame()) return 0;  // no Java frames

  {- -------------------------------------------
  (1) スタック中の javaVFrame の数を数える.
      ---------------------------------------- -}

      ResourceMark rm;
      RegisterMap reg_map(get_thread());
      javaVFrame *jvf = get_thread()->last_java_vframe(&reg_map);
      int n = 0;
      // tty->print_cr("CSD: counting frames on %s ...",
      //               JvmtiTrace::safe_get_thread_name(get_thread()));
      while (jvf != NULL) {
        methodOop method = jvf->method();
        // tty->print_cr("CSD: frame - method %s.%s - loc %d",
        //               method->klass_name()->as_C_string(),
        //               method->name()->as_C_string(),
        //               jvf->bci() );
        jvf = jvf->java_sender();
        n++;
      }

  {- -------------------------------------------
  (1) 結果をリターン
      ---------------------------------------- -}

      // tty->print_cr("CSD: frame count: %d", n);
      return n;
    }