--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/memory-block.cc	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,64 @@
+/* Shared pool of memory blocks for pool allocators.
+   Copyright (C) 2015-2017 Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "memory-block.h"
+#include "obstack.h"
+
+/* Global singleton-like instance.  */
+memory_block_pool memory_block_pool::instance;
+
+memory_block_pool::memory_block_pool () : m_blocks (NULL) {}
+
+/* Return all blocks from free list to the OS.  */
+void
+memory_block_pool::clear_free_list ()
+{
+  while (m_blocks)
+    {
+      block_list *next = m_blocks->m_next;
+      XDELETEVEC (m_blocks);
+      m_blocks = next;
+    }
+}
+
+/* Allocate a chunk for obstack.  Use the pool if requested chunk size matches
+   the size of blocks in the pool.  */
+void *
+mempool_obstack_chunk_alloc (size_t size)
+{
+  if (size == memory_block_pool::block_size)
+    return memory_block_pool::allocate ();
+  else
+    return XNEWVEC (char, size);
+}
+
+/* Free previously allocated obstack chunk.  */
+void
+mempool_obstack_chunk_free (void *chunk)
+{
+  size_t size = (reinterpret_cast<_obstack_chunk *> (chunk)->limit
+		 - reinterpret_cast<char *> (chunk));
+  if (size == memory_block_pool::block_size)
+    memory_block_pool::release (chunk);
+  else
+    XDELETEVEC (chunk);
+}