GCC Middle and Back End API Reference
memory-block.h
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1/* Shared pool of memory blocks for pool allocators.
2 Copyright (C) 2015-2024 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. */
27{
28public:
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;
33
35
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);
40
41private:
42 /* memory_block_pool singleton instance, defined in memory-block.cc. */
44
46 {
48 };
49
50 /* Free list. */
52};
53
54/* Allocate a single block. Reuse a previously returned block, if possible. */
55inline void *
57{
58 if (instance.m_blocks == NULL)
59 return XNEWVEC (char, block_size);
60
61 void *result = instance.m_blocks;
63 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (result, block_size));
64 return result;
65}
66
67/* Return UNCAST_BLOCK to the pool. */
68inline void
69memory_block_pool::release (void *uncast_block)
70{
71 block_list *block = new (uncast_block) block_list;
72 block->m_next = instance.m_blocks;
73 instance.m_blocks = block;
74
75 VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS ((char *)uncast_block
76 + sizeof (block_list),
78 - sizeof (block_list)));
79}
80
81extern void *mempool_obstack_chunk_alloc (size_t) ATTRIBUTE_MALLOC;
82extern void mempool_obstack_chunk_free (void *);
83
84#endif /* MEMORY_BLOCK_H */
Definition memory-block.h:27
static memory_block_pool instance
Definition memory-block.h:43
static const size_t freelist_size
Definition memory-block.h:32
memory_block_pool()
Definition memory-block.cc:29
static void trim(int nblocks=freelist_size)
Definition memory-block.cc:83
block_list * m_blocks
Definition memory-block.h:51
static void release(void *)
Definition memory-block.h:69
static const size_t block_size
Definition memory-block.h:30
void reduce_free_list(int)
Definition memory-block.cc:33
static void * allocate() ATTRIBUTE_MALLOC
Definition memory-block.h:56
void mempool_obstack_chunk_free(void *)
Definition memory-block.cc:71
void * mempool_obstack_chunk_alloc(size_t) ATTRIBUTE_MALLOC
Definition memory-block.cc:61
Definition memory-block.h:46
block_list * m_next
Definition memory-block.h:47
#define NULL
Definition system.h:50
#define VALGRIND_DISCARD(x)
Definition system.h:1222