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       1                 :             : /* Shared pool of memory blocks for pool allocators.
       2                 :             :    Copyright (C) 2015-2025 Free Software Foundation, Inc.
       3                 :             : 
       4                 :             : This file is part of GCC.
       5                 :             : 
       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)
       9                 :             : any later version.
      10                 :             : 
      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.
      15                 :             : 
      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/>.  */
      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.  */
      26                 :             : class memory_block_pool
      27                 :             : {
      28                 :             : public:
      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                 :             : 
      34                 :             :   memory_block_pool ();
      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                 :             : 
      41                 :             : private:
      42                 :             :   /* memory_block_pool singleton instance, defined in memory-block.cc.  */
      43                 :             :   static memory_block_pool instance;
      44                 :             : 
      45                 :             :   struct block_list
      46                 :             :   {
      47                 :             :     block_list *m_next;
      48                 :             :   };
      49                 :             : 
      50                 :             :   /* Free list.  */
      51                 :             :   block_list *m_blocks;
      52                 :             : };
      53                 :             : 
      54                 :             : /* Allocate a single block.  Reuse a previously returned block, if possible.  */
      55                 :             : inline void *
      56                 :   914256146 : memory_block_pool::allocate ()
      57                 :             : {
      58                 :   914256146 :   if (instance.m_blocks == NULL)
      59                 :    12267824 :     return XNEWVEC (char, block_size);
      60                 :             : 
      61                 :   901988322 :   void *result = instance.m_blocks;
      62                 :   901988322 :   instance.m_blocks = instance.m_blocks->m_next;
      63                 :   901988322 :   VALGRIND_DISCARD (VALGRIND_MAKE_MEM_UNDEFINED (result, block_size));
      64                 :   901988322 :   return result;
      65                 :             : }
      66                 :             : 
      67                 :             : /* Return UNCAST_BLOCK to the pool.  */
      68                 :             : inline void
      69                 :   913172838 : memory_block_pool::release (void *uncast_block)
      70                 :             : {
      71                 :   913172838 :   block_list *block = new (uncast_block) block_list;
      72                 :   913172838 :   block->m_next = instance.m_blocks;
      73                 :   913172838 :   instance.m_blocks = block;
      74                 :             : 
      75                 :             :   VALGRIND_DISCARD (VALGRIND_MAKE_MEM_NOACCESS ((char *)uncast_block
      76                 :             :                                                 + sizeof (block_list),
      77                 :             :                                                 block_size
      78                 :   913172838 :                                                 - sizeof (block_list)));
      79                 :   403927701 : }
      80                 :             : 
      81                 :             : extern void *mempool_obstack_chunk_alloc (size_t) ATTRIBUTE_MALLOC;
      82                 :             : extern void mempool_obstack_chunk_free (void *);
      83                 :             : 
      84                 :             : #endif /* MEMORY_BLOCK_H */