inline HeapWord* G1AllocRegion::attempt_allocation_force(size_t word_size,
                                                         bool bot_updates) {

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

      assert(bot_updates == _bot_updates, ar_ext_msg(this, "pre-condition"));
      assert(_alloc_region != NULL, ar_ext_msg(this, "not initialized properly"));

  {- -------------------------------------------
  (1) (トレース出力)
      ---------------------------------------- -}

      trace("forcing alloc");

  {- -------------------------------------------
  (1) G1AllocRegion::new_alloc_region_and_allocate() でメモリ確保を試み, 結果をリターンする.
      ついでに(トレース出力).
      ---------------------------------------- -}

      HeapWord* result = new_alloc_region_and_allocate(word_size, true /* force */);
      if (result != NULL) {
        trace("alloc forced", word_size, result);
        return result;
      }
      trace("alloc forced failed", word_size);
      return NULL;
    }