1 /* Shared pool of memory blocks for pool allocators.
2 Copyright (C) 2015-2022 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3, or (at your option)
11 GCC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
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/>. */
21 #ifndef MEMORY_BLOCK_H
22 #define MEMORY_BLOCK_H
24 /* Shared pool which allows other memory pools to reuse each others' allocated
25 memory blocks instead of calling free/malloc again. */
26 class memory_block_pool
29 /* Blocks have fixed size. This is necessary for sharing. */
30 static const size_t block_size
= 64 * 1024;
31 /* Number of blocks we keep in the freelists. */
32 static const size_t freelist_size
= 1024 * 1024 / block_size
;
36 static inline void *allocate () ATTRIBUTE_MALLOC
;
37 static inline void release (void *);
38 static void trim (int nblocks
= freelist_size
);
39 void reduce_free_list (int);
42 /* memory_block_pool singleton instance, defined in memory-block.cc. */
43 static memory_block_pool instance
;
54 /* Allocate a single block. Reuse a previously returned block, if possible. */
56 memory_block_pool::allocate ()
58 if (instance
.m_blocks
== NULL
)
59 return XNEWVEC (char, block_size
);
61 void *result
= instance
.m_blocks
;
62 instance
.m_blocks
= instance
.m_blocks
->m_next
;
63 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (result
, block_size
));
67 /* Return UNCAST_BLOCK to the pool. */
69 memory_block_pool::release (void *uncast_block
)
71 block_list
*block
= new (uncast_block
) block_list
;
72 block
->m_next
= instance
.m_blocks
;
73 instance
.m_blocks
= block
;
75 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS ((char *)uncast_block
76 + sizeof (block_list
),
78 - sizeof (block_list
)));
81 extern void *mempool_obstack_chunk_alloc (size_t) ATTRIBUTE_MALLOC
;
82 extern void mempool_obstack_chunk_free (void *);
84 #endif /* MEMORY_BLOCK_H */