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/* Shared pool of memory blocks for pool allocators.
Copyright (C) 2015-2020 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/>. */
#ifndef MEMORY_BLOCK_H
#define MEMORY_BLOCK_H
/* Shared pool which allows other memory pools to reuse each others' allocated
memory blocks instead of calling free/malloc again. */
class memory_block_pool
{
public:
/* Blocks have fixed size. This is necessary for sharing. */
static const size_t block_size = 64 * 1024;
/* Number of blocks we keep in the freelists. */
static const size_t freelist_size = 1024 * 1024 / block_size;
memory_block_pool ();
static inline void *allocate () ATTRIBUTE_MALLOC;
static inline void release (void *);
static void trim (int nblocks = freelist_size);
void reduce_free_list (int);
private:
/* memory_block_pool singleton instance, defined in memory-block.cc. */
static memory_block_pool instance;
struct block_list
{
block_list *m_next;
};
/* Free list. */
block_list *m_blocks;
};
/* Allocate a single block. Reuse a previously returned block, if possible. */
inline void *
memory_block_pool::allocate ()
{
if (instance.m_blocks == NULL)
return XNEWVEC (char, block_size);
void *result = instance.m_blocks;
instance.m_blocks = instance.m_blocks->m_next;
VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (result, block_size));
return result;
}
/* Return UNCAST_BLOCK to the pool. */
inline void
memory_block_pool::release (void *uncast_block)
{
block_list *block = new (uncast_block) block_list;
block->m_next = instance.m_blocks;
instance.m_blocks = block;
VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS ((char *)uncast_block
+ sizeof (block_list),
block_size
- sizeof (block_list)));
}
extern void *mempool_obstack_chunk_alloc (size_t) ATTRIBUTE_MALLOC;
extern void mempool_obstack_chunk_free (void *);
#endif /* MEMORY_BLOCK_H */
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