// This method is called whenever an attempt to promote an object
// fails. Some markOops will need preservation, some will not. Note
// that the entire eden is traversed after a failed promotion, with
// all forwarded headers replaced by the default markOop. This means
// it is not neccessary to preserve most markOops.

void PSScavenge::oop_promotion_failed(oop obj, markOop obj_mark) {

  {- -------------------------------------------
  (1) 失敗したことが後から認識できるよう, _promotion_failed フィールドを変更しておく.
      (確保失敗のケースでは, 後で PSScavenge::clean_up_failed_promotion() により後始末が行われる.
       See: PSScavenge::clean_up_failed_promotion())
      ---------------------------------------- -}

      _promotion_failed = true;

  {- -------------------------------------------
  (1) もし元の mark フィールドの値を保存しておく必要があれば, 
      PSScavenge::_preserved_mark_stack と PSScavenge::_preserved_oop_stack に
      処理対象のオブジェクトとその元の mark フィールド値を記録しておく.

      (なお, この記録処理は ThreadCritical で排他した状態で行っている)
      ---------------------------------------- -}

      if (obj_mark->must_be_preserved_for_promotion_failure(obj)) {
        // Should use per-worker private stakcs hetre rather than
        // locking a common pair of stacks.
        ThreadCritical tc;
        _preserved_oop_stack.push(obj);
        _preserved_mark_stack.push(obj_mark);
      }
    }