JNI_QUICK_ENTRY(jboolean, jni_IsAssignableFrom(JNIEnv *env, jclass sub, jclass super))

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

      JNIWrapper("IsSubclassOf");

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

      DTRACE_PROBE3(hotspot_jni, IsAssignableFrom__entry, env, sub, super);

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

      oop sub_mirror   = JNIHandles::resolve_non_null(sub);
      oop super_mirror = JNIHandles::resolve_non_null(super);

  {- -------------------------------------------
  (1) もしどちらかがプリミティブ型であれば, 返値は両方の型が一致するかどうかで判定.
      (一致するなら true, しないなら false)
      ---------------------------------------- -}

      if (java_lang_Class::is_primitive(sub_mirror) ||
          java_lang_Class::is_primitive(super_mirror)) {
        jboolean ret = (sub_mirror == super_mirror);

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

        DTRACE_PROBE1(hotspot_jni, IsAssignableFrom__return, ret);
        return ret;
      }

  {- -------------------------------------------
  (1) どちらかもプリミティブ型でなければ, Klass::is_subtype_of() の結果を返値とする.
      ---------------------------------------- -}

      klassOop sub_klass   = java_lang_Class::as_klassOop(sub_mirror);
      klassOop super_klass = java_lang_Class::as_klassOop(super_mirror);
      assert(sub_klass != NULL && super_klass != NULL, "invalid arguments to jni_IsAssignableFrom");
      jboolean ret = Klass::cast(sub_klass)->is_subtype_of(super_klass) ?
                       JNI_TRUE : JNI_FALSE;

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

      DTRACE_PROBE1(hotspot_jni, IsAssignableFrom__return, ret);

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

      return ret;
    JNI_END