JNI_QUICK_ENTRY(jboolean, jni_IsInstanceOf(JNIEnv *env, jobject obj, jclass clazz))

  {- -------------------------------------------
  (1) (デバッグ用の処理)
      (See: JNIWrapper)
      ---------------------------------------- -}

      JNIWrapper("IsInstanceOf");

  {- -------------------------------------------
  (1) (DTrace のフック点)
      ---------------------------------------- -}

      DTRACE_PROBE3(hotspot_jni, IsInstanceOf__entry, env, obj, clazz);

  {- -------------------------------------------
  (1) (変数宣言など)
      ---------------------------------------- -}

      jboolean ret = JNI_TRUE;

  {- -------------------------------------------
  (1) oopDesc::is_a() を呼んで判定する. 
      ---------------------------------------- -}

      if (obj != NULL) {
        ret = JNI_FALSE;
        klassOop k = java_lang_Class::as_klassOop(
          JNIHandles::resolve_non_null(clazz));
        if (k != NULL) {
          ret = JNIHandles::resolve_non_null(obj)->is_a(k) ? JNI_TRUE : JNI_FALSE;
        }
      }

  {- -------------------------------------------
  (1) (DTrace のフック点)
      ---------------------------------------- -}

      DTRACE_PROBE1(hotspot_jni, IsInstanceOf__return, ret);

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

      return ret;
    JNI_END