gcc/memory-block.cc

   1 /* Shared pool of memory blocks for pool allocators.
   2    Copyright (C) 2015-2021 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 3, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 #include "config.h"
  21 #include "system.h"
  22 #include "coretypes.h"
  23 #include "memory-block.h"
  24 #include "obstack.h"
  25
  26 /* Global singleton-like instance.  */
  27 memory_block_pool memory_block_pool::instance;
  28
  29 memory_block_pool::memory_block_pool () : m_blocks (NULL) {}
  30
  31 /* Reduce free list to NUM blocks and return remaining to malloc.  */
  32 void
  33 memory_block_pool::reduce_free_list (int num)
  34 {
  35   block_list **blocks = &m_blocks;
  36
  37   /* First skip NUM blocks.  */
  38
  39   for (;num > 0 && *blocks; num--)
  40     blocks = &(*blocks)->m_next;
  41
  42   if (!*blocks)
  43     return;
  44
  45   /* And free the remainder of them.  */
  46
  47   block_list *to_free = *blocks;
  48   *blocks = NULL;
  49
  50   while (to_free)
  51     {
  52       block_list *next = to_free->m_next;
  53       XDELETEVEC (to_free);
  54       to_free = next;
  55     }
  56 }
  57
  58 /* Allocate a chunk for obstack.  Use the pool if requested chunk size matches
  59    the size of blocks in the pool.  */
  60 void *
  61 mempool_obstack_chunk_alloc (size_t size)
  62 {
  63   if (size == memory_block_pool::block_size)
  64     return memory_block_pool::allocate ();
  65   else
  66     return XNEWVEC (char, size);
  67 }
  68
  69 /* Free previously allocated obstack chunk.  */
  70 void
  71 mempool_obstack_chunk_free (void *chunk)
  72 {
  73   size_t size = (reinterpret_cast<_obstack_chunk *> (chunk)->limit
  74                  - reinterpret_cast<char *> (chunk));
  75   if (size == memory_block_pool::block_size)
  76     memory_block_pool::release (chunk);
  77   else
  78     XDELETEVEC (chunk);
  79 }
  80
  81 /* Return allocated memory back to malloc (and to system).  */
  82 void
  83 memory_block_pool::trim (int num)
  84 {
  85   instance.reduce_free_list (num);
  86 }