gcc/alloc-pool.c

   1 /* Functions to support a pool of allocatable objects.
   2    Copyright (C) 1987, 1997, 1998, 1999, 2000, 2001, 2003
   3    Free Software Foundation, Inc.
   4    Contributed by Daniel Berlin <dan@cgsoftware.com>
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 2, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING.  If not, write to the Free
  20 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  21 02111-1307, USA.  */
  22
  23 #include "config.h"
  24 #include "system.h"
  25 #include "alloc-pool.h"
  26
  27 /* Redefine abort to report an internal error w/o coredump, and
  28    reporting the location of the error in the source file.  This logic
  29    is duplicated in rtl.h and tree.h because every file that needs the
  30    special abort includes one or both.  toplev.h gets too few files,
  31    system.h gets too many.  */
  32
  33 extern void fancy_abort (const char *, int, const char *)
  34     ATTRIBUTE_NORETURN;
  35 #define abort() fancy_abort (__FILE__, __LINE__, __FUNCTION__)
  36
  37 #define align_eight(x) (((x+7) >> 3) << 3)
  38
  39 /* The internal allocation object.  */
  40 typedef struct allocation_object_def
  41 {
  42 #ifdef ENABLE_CHECKING
  43   /* The ID of alloc pool which the object was allocated from.  */
  44   ALLOC_POOL_ID_TYPE id;
  45 #endif
  46
  47   union
  48     {
  49       /* The data of the object.  */
  50       char data[1];
  51
  52       /* Because we want any type of data to be well aligned after the ID,
  53          the following elements are here.  They are never accessed so
  54          the allocated object may be even smaller than this structure.  */
  55       char *align_p;
  56       HOST_WIDEST_INT align_i;
  57       long double align_ld;
  58     } u;
  59 } allocation_object;
  60
  61 /* Convert a pointer to allocation_object from a pointer to user data.  */
  62 #define ALLOCATION_OBJECT_PTR_FROM_USER_PTR(X)                          \
  63    ((allocation_object *) (((char *) (X))                               \
  64                            - offsetof (allocation_object, u.data)))
  65
  66 /* Convert a pointer to user data from a pointer to allocation_object.  */
  67 #define USER_PTR_FROM_ALLOCATION_OBJECT_PTR(X)                          \
  68    ((void *) (((allocation_object *) (X))->u.data))
  69
  70 #ifdef ENABLE_CHECKING
  71 /* Last used ID.  */
  72 static ALLOC_POOL_ID_TYPE last_id;
  73 #endif
  74
  75 /* Create a pool of things of size SIZE, with NUM in each block we
  76    allocate.  */
  77
  78 alloc_pool
  79 create_alloc_pool (const char *name, size_t size, size_t num)
  80 {
  81   alloc_pool pool;
  82   size_t pool_size, header_size;
  83
  84   if (!name)
  85     abort ();
  86
  87   /* Make size large enough to store the list header.  */
  88   if (size < sizeof (alloc_pool_list))
  89     size = sizeof (alloc_pool_list);
  90
  91   /* Now align the size to a multiple of 4.  */
  92   size = align_eight (size);
  93
  94 #ifdef ENABLE_CHECKING
  95   /* Add the aligned size of ID.  */
  96   size += offsetof (allocation_object, u.data);
  97 #endif
  98
  99   /* Um, we can't really allocate 0 elements per block.  */
 100   if (num == 0)
 101     abort ();
 102
 103   /* Find the size of the pool structure, and the name.  */
 104   pool_size = sizeof (struct alloc_pool_def);
 105
 106   /* and allocate that much memory.  */
 107   pool = xmalloc (pool_size);
 108
 109   /* Now init the various pieces of our pool structure.  */
 110   pool->name = xstrdup (name);
 111   pool->elt_size = size;
 112   pool->elts_per_block = num;
 113
 114   /* List header size should be a multiple of 8.  */
 115   header_size = align_eight (sizeof (struct alloc_pool_list_def));
 116
 117   pool->block_size = (size * num) + header_size;
 118   pool->free_list = NULL;
 119   pool->elts_allocated = 0;
 120   pool->elts_free = 0;
 121   pool->blocks_allocated = 0;
 122   pool->block_list = NULL;
 123
 124 #ifdef ENABLE_CHECKING
 125   /* Increase the last used ID and use it for this pool.
 126      ID == 0 is used for free elements of pool so skip it.  */
 127   last_id++;
 128   if (last_id == 0)
 129     last_id++;
 130
 131   pool->id = last_id;
 132 #endif
 133
 134   return (pool);
 135 }
 136
 137 /* Free all memory allocated for the given memory pool.  */
 138 void
 139 free_alloc_pool (alloc_pool pool)
 140 {
 141   alloc_pool_list block, next_block;
 142
 143 #ifdef ENABLE_CHECKING
 144   if (!pool)
 145     abort ();
 146 #endif
 147
 148   /* Free each block allocated to the pool.  */
 149   for (block = pool->block_list; block != NULL; block = next_block)
 150     {
 151       next_block = block->next;
 152       free (block);
 153     }
 154   /* Lastly, free the pool and the name.  */
 155   free (pool->name);
 156 #ifdef ENABLE_CHECKING
 157   memset (pool, 0xaf, sizeof (*pool));
 158 #endif
 159   free (pool);
 160 }
 161
 162 /* Allocates one element from the pool specified.  */
 163 void *
 164 pool_alloc (alloc_pool pool)
 165 {
 166   alloc_pool_list header;
 167   char *block;
 168
 169 #ifdef ENABLE_CHECKING
 170   if (!pool)
 171     abort ();
 172 #endif
 173
 174   /* If there are no more free elements, make some more!.  */
 175   if (!pool->free_list)
 176     {
 177       size_t i;
 178       alloc_pool_list block_header;
 179
 180       /* Make the block.  */
 181       block = xmalloc (pool->block_size);
 182       block_header = (alloc_pool_list) block;
 183       block += align_eight (sizeof (struct alloc_pool_list_def));
 184
 185       /* Throw it on the block list.  */
 186       block_header->next = pool->block_list;
 187       pool->block_list = block_header;
 188
 189       /* Now put the actual block pieces onto the free list.  */
 190       for (i = 0; i < pool->elts_per_block; i++, block += pool->elt_size)
 191       {
 192 #ifdef ENABLE_CHECKING
 193         /* Mark the element to be free.  */
 194         ((allocation_object *) block)->id = 0;
 195 #endif
 196         header = (alloc_pool_list) USER_PTR_FROM_ALLOCATION_OBJECT_PTR (block);
 197         header->next = pool->free_list;
 198         pool->free_list = header;
 199       }
 200       /* Also update the number of elements we have free/allocated, and
 201          increment the allocated block count.  */
 202       pool->elts_allocated += pool->elts_per_block;
 203       pool->elts_free += pool->elts_per_block;
 204       pool->blocks_allocated += 1;
 205     }
 206
 207   /* Pull the first free element from the free list, and return it.  */
 208   header = pool->free_list;
 209   pool->free_list = header->next;
 210   pool->elts_free--;
 211
 212 #ifdef ENABLE_CHECKING
 213   /* Set the ID for element.  */
 214   ALLOCATION_OBJECT_PTR_FROM_USER_PTR (header)->id = pool->id;
 215 #endif
 216
 217   return ((void *) header);
 218 }
 219
 220 /* Puts PTR back on POOL's free list.  */
 221 void
 222 pool_free (alloc_pool pool, void *ptr)
 223 {
 224   alloc_pool_list header;
 225
 226 #ifdef ENABLE_CHECKING
 227   if (!ptr)
 228     abort ();
 229
 230   memset (ptr, 0xaf, pool->elt_size - offsetof (allocation_object, u.data));
 231
 232   /* Check whether the PTR was allocated from POOL.  */
 233   if (pool->id != ALLOCATION_OBJECT_PTR_FROM_USER_PTR (ptr)->id)
 234     abort ();
 235
 236   /* Mark the element to be free.  */
 237   ALLOCATION_OBJECT_PTR_FROM_USER_PTR (ptr)->id = 0;
 238 #else
 239   /* Check if we free more than we allocated, which is Bad (TM).  */
 240   if (pool->elts_free + 1 > pool->elts_allocated)
 241     abort ();
 242 #endif
 243
 244   header = (alloc_pool_list) ptr;
 245   header->next = pool->free_list;
 246   pool->free_list = header;
 247   pool->elts_free++;
 248 }