gcc/alloc-pool.c

   1 /* Functions to support a pool of allocatable objects.
   2    Copyright (C) 1987, 1997, 1998, 1999, 2000, 2001, 2003, 2004, 2005
   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, 51 Franklin Street, Fifth Floor, Boston, MA
  21 02110-1301, USA.  */
  22
  23 #include "config.h"
  24 #include "system.h"
  25 #include "alloc-pool.h"
  26 #include "hashtab.h"
  27
  28 #define align_eight(x) (((x+7) >> 3) << 3)
  29
  30 /* The internal allocation object.  */
  31 typedef struct allocation_object_def
  32 {
  33 #ifdef ENABLE_CHECKING
  34   /* The ID of alloc pool which the object was allocated from.  */
  35   ALLOC_POOL_ID_TYPE id;
  36 #endif
  37
  38   union
  39     {
  40       /* The data of the object.  */
  41       char data[1];
  42
  43       /* Because we want any type of data to be well aligned after the ID,
  44          the following elements are here.  They are never accessed so
  45          the allocated object may be even smaller than this structure.  */
  46       char *align_p;
  47       HOST_WIDEST_INT align_i;
  48       long double align_ld;
  49     } u;
  50 } allocation_object;
  51
  52 /* Convert a pointer to allocation_object from a pointer to user data.  */
  53 #define ALLOCATION_OBJECT_PTR_FROM_USER_PTR(X)                          \
  54    ((allocation_object *) (((char *) (X))                               \
  55                            - offsetof (allocation_object, u.data)))
  56
  57 /* Convert a pointer to user data from a pointer to allocation_object.  */
  58 #define USER_PTR_FROM_ALLOCATION_OBJECT_PTR(X)                          \
  59    ((void *) (((allocation_object *) (X))->u.data))
  60
  61 #ifdef ENABLE_CHECKING
  62 /* Last used ID.  */
  63 static ALLOC_POOL_ID_TYPE last_id;
  64 #endif
  65
  66 #ifdef GATHER_STATISTICS
  67
  68 /* Store information about each particular alloc_pool.  */
  69 struct alloc_pool_descriptor
  70 {
  71   const char *name;
  72   int allocated;
  73   int created;
  74   int peak;
  75   int current;
  76 };
  77
  78 /* Hashtable mapping alloc_pool names to descriptors.  */
  79 static htab_t alloc_pool_hash;
  80
  81 /* Hashtable helpers.  */
  82 static hashval_t
  83 hash_descriptor (const void *p)
  84 {
  85   const struct alloc_pool_descriptor *d = p;
  86   return htab_hash_pointer (d->name);
  87 }
  88 static int
  89 eq_descriptor (const void *p1, const void *p2)
  90 {
  91   const struct alloc_pool_descriptor *d = p1;
  92   return d->name == p2;
  93 }
  94
  95 /* For given name, return descriptor, create new if needed.  */
  96 static struct alloc_pool_descriptor *
  97 alloc_pool_descriptor (const char *name)
  98 {
  99   struct alloc_pool_descriptor **slot;
 100
 101   if (!alloc_pool_hash)
 102     alloc_pool_hash = htab_create (10, hash_descriptor, eq_descriptor, NULL);
 103
 104   slot = (struct alloc_pool_descriptor **)
 105     htab_find_slot_with_hash (alloc_pool_hash, name,
 106                               htab_hash_pointer (name),
 107                               1);
 108   if (*slot)
 109     return *slot;
 110   *slot = xcalloc (sizeof (**slot), 1);
 111   (*slot)->name = name;
 112   return *slot;
 113 }
 114 #endif
 115
 116 /* Create a pool of things of size SIZE, with NUM in each block we
 117    allocate.  */
 118
 119 alloc_pool
 120 create_alloc_pool (const char *name, size_t size, size_t num)
 121 {
 122   alloc_pool pool;
 123   size_t pool_size, header_size;
 124 #ifdef GATHER_STATISTICS
 125   struct alloc_pool_descriptor *desc;
 126 #endif
 127
 128   gcc_assert (name);
 129
 130   /* Make size large enough to store the list header.  */
 131   if (size < sizeof (alloc_pool_list))
 132     size = sizeof (alloc_pool_list);
 133
 134   /* Now align the size to a multiple of 4.  */
 135   size = align_eight (size);
 136
 137 #ifdef ENABLE_CHECKING
 138   /* Add the aligned size of ID.  */
 139   size += offsetof (allocation_object, u.data);
 140 #endif
 141
 142   /* Um, we can't really allocate 0 elements per block.  */
 143   gcc_assert (num);
 144
 145   /* Find the size of the pool structure, and the name.  */
 146   pool_size = sizeof (struct alloc_pool_def);
 147
 148   /* and allocate that much memory.  */
 149   pool = xmalloc (pool_size);
 150
 151   /* Now init the various pieces of our pool structure.  */
 152   pool->name = /*xstrdup (name)*/name;
 153 #ifdef GATHER_STATISTICS
 154   desc = alloc_pool_descriptor (name);
 155   desc->created++;
 156 #endif
 157   pool->elt_size = size;
 158   pool->elts_per_block = num;
 159
 160   /* List header size should be a multiple of 8.  */
 161   header_size = align_eight (sizeof (struct alloc_pool_list_def));
 162
 163   pool->block_size = (size * num) + header_size;
 164   pool->free_list = NULL;
 165   pool->elts_allocated = 0;
 166   pool->elts_free = 0;
 167   pool->blocks_allocated = 0;
 168   pool->block_list = NULL;
 169
 170 #ifdef ENABLE_CHECKING
 171   /* Increase the last used ID and use it for this pool.
 172      ID == 0 is used for free elements of pool so skip it.  */
 173   last_id++;
 174   if (last_id == 0)
 175     last_id++;
 176
 177   pool->id = last_id;
 178 #endif
 179
 180   return (pool);
 181 }
 182
 183 /* Free all memory allocated for the given memory pool.  */
 184 void
 185 free_alloc_pool (alloc_pool pool)
 186 {
 187   alloc_pool_list block, next_block;
 188 #ifdef GATHER_STATISTICS
 189   struct alloc_pool_descriptor *desc = alloc_pool_descriptor (pool->name);
 190 #endif
 191
 192   gcc_assert (pool);
 193
 194   /* Free each block allocated to the pool.  */
 195   for (block = pool->block_list; block != NULL; block = next_block)
 196     {
 197       next_block = block->next;
 198       free (block);
 199 #ifdef GATHER_STATISTICS
 200       desc->current -= pool->block_size;
 201 #endif
 202     }
 203 #ifdef ENABLE_CHECKING
 204   memset (pool, 0xaf, sizeof (*pool));
 205 #endif
 206   /* Lastly, free the pool.  */
 207   free (pool);
 208 }
 209
 210 /* Allocates one element from the pool specified.  */
 211 void *
 212 pool_alloc (alloc_pool pool)
 213 {
 214   alloc_pool_list header;
 215   char *block;
 216 #ifdef GATHER_STATISTICS
 217   struct alloc_pool_descriptor *desc = alloc_pool_descriptor (pool->name);
 218
 219   desc->allocated+=pool->elt_size;
 220 #endif
 221
 222   gcc_assert (pool);
 223
 224   /* If there are no more free elements, make some more!.  */
 225   if (!pool->free_list)
 226     {
 227       size_t i;
 228       alloc_pool_list block_header;
 229
 230       /* Make the block.  */
 231       block = xmalloc (pool->block_size);
 232       block_header = (alloc_pool_list) block;
 233       block += align_eight (sizeof (struct alloc_pool_list_def));
 234 #ifdef GATHER_STATISTICS
 235       desc->current += pool->block_size;
 236       if (desc->peak < desc->current)
 237         desc->peak = desc->current;
 238 #endif
 239
 240       /* Throw it on the block list.  */
 241       block_header->next = pool->block_list;
 242       pool->block_list = block_header;
 243
 244       /* Now put the actual block pieces onto the free list.  */
 245       for (i = 0; i < pool->elts_per_block; i++, block += pool->elt_size)
 246       {
 247 #ifdef ENABLE_CHECKING
 248         /* Mark the element to be free.  */
 249         ((allocation_object *) block)->id = 0;
 250 #endif
 251         header = (alloc_pool_list) USER_PTR_FROM_ALLOCATION_OBJECT_PTR (block);
 252         header->next = pool->free_list;
 253         pool->free_list = header;
 254       }
 255       /* Also update the number of elements we have free/allocated, and
 256          increment the allocated block count.  */
 257       pool->elts_allocated += pool->elts_per_block;
 258       pool->elts_free += pool->elts_per_block;
 259       pool->blocks_allocated += 1;
 260     }
 261
 262   /* Pull the first free element from the free list, and return it.  */
 263   header = pool->free_list;
 264   pool->free_list = header->next;
 265   pool->elts_free--;
 266
 267 #ifdef ENABLE_CHECKING
 268   /* Set the ID for element.  */
 269   ALLOCATION_OBJECT_PTR_FROM_USER_PTR (header)->id = pool->id;
 270 #endif
 271
 272   return ((void *) header);
 273 }
 274
 275 /* Puts PTR back on POOL's free list.  */
 276 void
 277 pool_free (alloc_pool pool, void *ptr)
 278 {
 279   alloc_pool_list header;
 280
 281   gcc_assert (ptr);
 282
 283 #ifdef ENABLE_CHECKING
 284   memset (ptr, 0xaf, pool->elt_size - offsetof (allocation_object, u.data));
 285
 286   /* Check whether the PTR was allocated from POOL.  */
 287   gcc_assert (pool->id == ALLOCATION_OBJECT_PTR_FROM_USER_PTR (ptr)->id);
 288
 289   /* Mark the element to be free.  */
 290   ALLOCATION_OBJECT_PTR_FROM_USER_PTR (ptr)->id = 0;
 291 #else
 292   /* Check if we free more than we allocated, which is Bad (TM).  */
 293   gcc_assert (pool->elts_free < pool->elts_allocated);
 294 #endif
 295
 296   header = (alloc_pool_list) ptr;
 297   header->next = pool->free_list;
 298   pool->free_list = header;
 299   pool->elts_free++;
 300 }
 301 /* Output per-alloc_pool statistics.  */
 302 #ifdef GATHER_STATISTICS
 303
 304 /* Used to accumulate statistics about alloc_pool sizes.  */
 305 struct output_info
 306 {
 307   int count;
 308   int size;
 309 };
 310
 311 /* Called via htab_traverse.  Output alloc_pool descriptor pointed out by SLOT
 312    and update statistics.  */
 313 static int
 314 print_statistics (void **slot, void *b)
 315 {
 316   struct alloc_pool_descriptor *d = (struct alloc_pool_descriptor *) *slot;
 317   struct output_info *i = (struct output_info *) b;
 318
 319   if (d->allocated)
 320     {
 321       fprintf (stderr, "%-21s %6d %10d %10d %10d\n", d->name,
 322                d->created, d->allocated, d->peak, d->current);
 323       i->size += d->allocated;
 324       i->count += d->created;
 325     }
 326   return 1;
 327 }
 328 #endif
 329
 330 /* Output per-alloc_pool memory usage statistics.  */
 331 void dump_alloc_pool_statistics (void)
 332 {
 333 #ifdef GATHER_STATISTICS
 334   struct output_info info;
 335
 336   if (!alloc_pool_hash)
 337     return;
 338
 339   fprintf (stderr, "\nAlloc-pool Kind        Pools  Allocated      Peak        Leak\n");
 340   fprintf (stderr, "-------------------------------------------------------------\n");
 341   info.count = 0;
 342   info.size = 0;
 343   htab_traverse (alloc_pool_hash, print_statistics, &info);
 344   fprintf (stderr, "-------------------------------------------------------------\n");
 345   fprintf (stderr, "%-20s %7d %10d\n",
 346            "Total", info.count, info.size);
 347   fprintf (stderr, "-------------------------------------------------------------\n");
 348 #endif
 349 }