85 lines
2.4 KiB
C++
85 lines
2.4 KiB
C++
/* Shared pool of memory blocks for pool allocators.
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Copyright (C) 2015-2021 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3, or (at your option)
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any later version.
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GCC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING3. If not see
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<http://www.gnu.org/licenses/>. */
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#ifndef MEMORY_BLOCK_H
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#define MEMORY_BLOCK_H
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/* Shared pool which allows other memory pools to reuse each others' allocated
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memory blocks instead of calling free/malloc again. */
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class memory_block_pool
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{
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public:
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/* Blocks have fixed size. This is necessary for sharing. */
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static const size_t block_size = 64 * 1024;
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/* Number of blocks we keep in the freelists. */
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static const size_t freelist_size = 1024 * 1024 / block_size;
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memory_block_pool ();
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static inline void *allocate () ATTRIBUTE_MALLOC;
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static inline void release (void *);
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static void trim (int nblocks = freelist_size);
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void reduce_free_list (int);
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private:
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/* memory_block_pool singleton instance, defined in memory-block.cc. */
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static memory_block_pool instance;
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struct block_list
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{
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block_list *m_next;
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};
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/* Free list. */
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block_list *m_blocks;
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};
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/* Allocate a single block. Reuse a previously returned block, if possible. */
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inline void *
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memory_block_pool::allocate ()
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{
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if (instance.m_blocks == NULL)
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return XNEWVEC (char, block_size);
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void *result = instance.m_blocks;
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instance.m_blocks = instance.m_blocks->m_next;
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VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (result, block_size));
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return result;
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}
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/* Return UNCAST_BLOCK to the pool. */
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inline void
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memory_block_pool::release (void *uncast_block)
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{
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block_list *block = new (uncast_block) block_list;
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block->m_next = instance.m_blocks;
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instance.m_blocks = block;
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VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS ((char *)uncast_block
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+ sizeof (block_list),
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block_size
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- sizeof (block_list)));
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}
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extern void *mempool_obstack_chunk_alloc (size_t) ATTRIBUTE_MALLOC;
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extern void mempool_obstack_chunk_free (void *);
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#endif /* MEMORY_BLOCK_H */
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