1/* Shared pool of memory blocks for pool allocators.
2 Copyright (C) 2015-2017 Free Software Foundation, Inc.
3
4This file is part of GCC.
5
6GCC is free software; you can redistribute it and/or modify
7it under the terms of the GNU General Public License as published by
8the Free Software Foundation; either version 3, or (at your option)
9any later version.
10
11GCC is distributed in the hope that it will be useful,
12but WITHOUT ANY WARRANTY; without even the implied warranty of
13MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14GNU General Public License for more details.
15
16You should have received a copy of the GNU General Public License
17along with GCC; see the file COPYING3. If not see
18<http://www.gnu.org/licenses/>. */
19
20
21#ifndef MEMORY_BLOCK_H
22#define MEMORY_BLOCK_H
23
24/* Shared pool which allows other memory pools to reuse each others' allocated
25 memory blocks instead of calling free/malloc again. */
26class memory_block_pool
27{
28public:
29 /* Blocks have fixed size. This is necessary for sharing. */
30 static const size_t block_size = 64 * 1024;
31
32 memory_block_pool ();
33
34 static inline void *allocate () ATTRIBUTE_MALLOC;
35 static inline void release (void *);
36 void clear_free_list ();
37
38private:
39 /* memory_block_pool singleton instance, defined in memory-block.cc. */
40 static memory_block_pool instance;
41
42 struct block_list
43 {
44 block_list *m_next;
45 };
46
47 /* Free list. */
48 block_list *m_blocks;
49};
50
51/* Allocate a single block. Reuse a previously returned block, if possible. */
52inline void *
53memory_block_pool::allocate ()
54{
55 if (instance.m_blocks == NULL)
56 return XNEWVEC (char, block_size);
57
58 void *result = instance.m_blocks;
59 instance.m_blocks = instance.m_blocks->m_next;
60 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (result, block_size));
61 return result;
62}
63
64/* Return UNCAST_BLOCK to the pool. */
65inline void
66memory_block_pool::release (void *uncast_block)
67{
68 block_list *block = new (uncast_block) block_list;
69 block->m_next = instance.m_blocks;
70 instance.m_blocks = block;
71}
72
73extern void *mempool_obstack_chunk_alloc (size_t) ATTRIBUTE_MALLOC;
74extern void mempool_obstack_chunk_free (void *);
75
76#endif /* MEMORY_BLOCK_H */
77