char* ReservedSpace::reserve_and_align(const size_t reserve_size,
                                       const size_t prefix_size,
                                       const size_t prefix_align,
                                       const size_t suffix_size,
                                       const size_t suffix_align)
{

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

      assert(reserve_size > prefix_size + suffix_size, "should not be here");

  {- -------------------------------------------
  (1) os::reserve_memory() でメモリ領域を確保し, 
      ReservedSpace::align_reserved_region() でアラインさせた結果を取得.

      (なお, os::reserve_memory() が失敗すれば, ここで NULL をリターン)
      ---------------------------------------- -}

      char* raw_addr = os::reserve_memory(reserve_size, NULL, prefix_align);
      if (raw_addr == NULL) return NULL;

      char* result = align_reserved_region(raw_addr, reserve_size, prefix_size,
                                           prefix_align, suffix_size,
                                           suffix_align);
      if (result == NULL && !os::release_memory(raw_addr, reserve_size)) {
        fatal("os::release_memory failed");
      }

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

    #ifdef ASSERT
      if (result != NULL) {
        const size_t raw = size_t(raw_addr);
        const size_t res = size_t(result);
        assert(res >= raw, "alignment decreased start addr");
        assert(res + prefix_size + suffix_size <= raw + reserve_size,
               "alignment increased end addr");
        assert((res & prefix_align - 1) == 0, "bad alignment of prefix");
        assert((res + prefix_size & suffix_align - 1) == 0,
               "bad alignment of suffix");
      }
    #endif

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

      return result;
    }