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, 2006,
   3    2007, 2008, 2010  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 3, 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 COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "alloc-pool.h"
  25 #include "hashtab.h"
  26
  27 #define align_eight(x) (((x+7) >> 3) << 3)
  28
  29 /* The internal allocation object.  */
  30 typedef struct allocation_object_def
  31 {
  32 #ifdef ENABLE_CHECKING
  33   /* The ID of alloc pool which the object was allocated from.  */
  34   ALLOC_POOL_ID_TYPE id;
  35 #endif
  36
  37   union
  38     {
  39       /* The data of the object.  */
  40       char data[1];
  41
  42       /* Because we want any type of data to be well aligned after the ID,
  43          the following elements are here.  They are never accessed so
  44          the allocated object may be even smaller than this structure.
  45          We do not care about alignment for floating-point types.  */
  46       char *align_p;
  47       HOST_WIDEST_INT align_i;
  48     } u;
  49 } allocation_object;
  50
  51 /* Convert a pointer to allocation_object from a pointer to user data.  */
  52 #define ALLOCATION_OBJECT_PTR_FROM_USER_PTR(X)                          \
  53    ((allocation_object *) (((char *) (X))                               \
  54                            - offsetof (allocation_object, u.data)))
  55
  56 /* Convert a pointer to user data from a pointer to allocation_object.  */
  57 #define USER_PTR_FROM_ALLOCATION_OBJECT_PTR(X)                          \
  58    ((void *) (((allocation_object *) (X))->u.data))
  59
  60 #ifdef ENABLE_CHECKING
  61 /* Last used ID.  */
  62 static ALLOC_POOL_ID_TYPE last_id;
  63 #endif
  64
  65 #ifdef GATHER_STATISTICS
  66
  67 /* Store information about each particular alloc_pool.  Note that this
  68    will underestimate the amount the amount of storage used by a small amount:
  69    1) The overhead in a pool is not accounted for.
  70    2) The unallocated elements in a block are not accounted for.  Note
  71    that this can at worst case be one element smaller that the block
  72    size for that pool.  */
  73 struct alloc_pool_descriptor
  74 {
  75   const char *name;
  76   /* Number of pools allocated.  */
  77   unsigned long created;
  78   /* Gross allocated storage.  */
  79   unsigned long allocated;
  80   /* Amount of currently active storage. */
  81   unsigned long current;
  82   /* Peak amount of storage used.  */
  83   unsigned long peak;
  84   /* Size of element in the pool.  */
  85   int elt_size;
  86 };
  87
  88 /* Hashtable mapping alloc_pool names to descriptors.  */
  89 static htab_t alloc_pool_hash;
  90
  91 /* Hashtable helpers.  */
  92 static hashval_t
  93 hash_descriptor (const void *p)
  94 {
  95   const struct alloc_pool_descriptor *const d =
  96     (const struct alloc_pool_descriptor * )p;
  97   return htab_hash_pointer (d->name);
  98 }
  99 static int
 100 eq_descriptor (const void *p1, const void *p2)
 101 {
 102   const struct alloc_pool_descriptor *const d =
 103     (const struct alloc_pool_descriptor *) p1;
 104   return d->name == p2;
 105 }
 106
 107 /* For given name, return descriptor, create new if needed.  */
 108 static struct alloc_pool_descriptor *
 109 alloc_pool_descriptor (const char *name)
 110 {
 111   struct alloc_pool_descriptor **slot;
 112
 113   if (!alloc_pool_hash)
 114     alloc_pool_hash = htab_create (10, hash_descriptor, eq_descriptor, NULL);
 115
 116   slot = (struct alloc_pool_descriptor **)
 117     htab_find_slot_with_hash (alloc_pool_hash, name,
 118                               htab_hash_pointer (name),
 119                               INSERT);
 120   if (*slot)
 121     return *slot;
 122   *slot = XCNEW (struct alloc_pool_descriptor);
 123   (*slot)->name = name;
 124   return *slot;
 125 }
 126 #endif
 127
 128 /* Create a pool of things of size SIZE, with NUM in each block we
 129    allocate.  */
 130
 131 alloc_pool
 132 create_alloc_pool (const char *name, size_t size, size_t num)
 133 {
 134   alloc_pool pool;
 135   size_t header_size;
 136 #ifdef GATHER_STATISTICS
 137   struct alloc_pool_descriptor *desc;
 138 #endif
 139
 140   gcc_checking_assert (name);
 141
 142   /* Make size large enough to store the list header.  */
 143   if (size < sizeof (alloc_pool_list))
 144     size = sizeof (alloc_pool_list);
 145
 146   /* Now align the size to a multiple of 4.  */
 147   size = align_eight (size);
 148
 149 #ifdef ENABLE_CHECKING
 150   /* Add the aligned size of ID.  */
 151   size += offsetof (allocation_object, u.data);
 152 #endif
 153
 154   /* Um, we can't really allocate 0 elements per block.  */
 155   gcc_checking_assert (num);
 156
 157   /* Allocate memory for the pool structure.  */
 158   pool = XNEW (struct alloc_pool_def);
 159
 160   /* Now init the various pieces of our pool structure.  */
 161   pool->name = /*xstrdup (name)*/name;
 162 #ifdef GATHER_STATISTICS
 163   desc = alloc_pool_descriptor (name);
 164   desc->elt_size = size;
 165   desc->created++;
 166 #endif
 167   pool->elt_size = size;
 168   pool->elts_per_block = num;
 169
 170   /* List header size should be a multiple of 8.  */
 171   header_size = align_eight (sizeof (struct alloc_pool_list_def));
 172
 173   pool->block_size = (size * num) + header_size;
 174   pool->returned_free_list = NULL;
 175   pool->virgin_free_list = NULL;
 176   pool->virgin_elts_remaining = 0;
 177   pool->elts_allocated = 0;
 178   pool->elts_free = 0;
 179   pool->blocks_allocated = 0;
 180   pool->block_list = NULL;
 181
 182 #ifdef ENABLE_CHECKING
 183   /* Increase the last used ID and use it for this pool.
 184      ID == 0 is used for free elements of pool so skip it.  */
 185   last_id++;
 186   if (last_id == 0)
 187     last_id++;
 188
 189   pool->id = last_id;
 190 #endif
 191
 192   return (pool);
 193 }
 194
 195 /* Free all memory allocated for the given memory pool.  */
 196 void
 197 empty_alloc_pool (alloc_pool pool)
 198 {
 199   alloc_pool_list block, next_block;
 200 #ifdef GATHER_STATISTICS
 201   struct alloc_pool_descriptor *desc = alloc_pool_descriptor (pool->name);
 202 #endif
 203
 204   gcc_checking_assert (pool);
 205
 206   /* Free each block allocated to the pool.  */
 207   for (block = pool->block_list; block != NULL; block = next_block)
 208     {
 209       next_block = block->next;
 210       free (block);
 211     }
 212
 213 #ifdef GATHER_STATISTICS
 214   desc->current -= (pool->elts_allocated - pool->elts_free) * pool->elt_size;
 215 #endif
 216   pool->returned_free_list = NULL;
 217   pool->virgin_free_list = NULL;
 218   pool->virgin_elts_remaining = 0;
 219   pool->elts_allocated = 0;
 220   pool->elts_free = 0;
 221   pool->blocks_allocated = 0;
 222   pool->block_list = NULL;
 223 }
 224
 225 /* Free all memory allocated for the given memory pool and the pool itself.  */
 226 void
 227 free_alloc_pool (alloc_pool pool)
 228 {
 229   /* First empty the pool.  */
 230   empty_alloc_pool (pool);
 231 #ifdef ENABLE_CHECKING
 232   memset (pool, 0xaf, sizeof (*pool));
 233 #endif
 234   /* Lastly, free the pool.  */
 235   free (pool);
 236 }
 237
 238 /* Frees the alloc_pool, if it is empty and zero *POOL in this case.  */
 239 void
 240 free_alloc_pool_if_empty (alloc_pool *pool)
 241 {
 242   if ((*pool)->elts_free == (*pool)->elts_allocated)
 243     {
 244       free_alloc_pool (*pool);
 245       *pool = NULL;
 246     }
 247 }
 248
 249 /* Allocates one element from the pool specified.  */
 250 void *
 251 pool_alloc (alloc_pool pool)
 252 {
 253   alloc_pool_list header;
 254 #ifdef GATHER_STATISTICS
 255   struct alloc_pool_descriptor *desc = alloc_pool_descriptor (pool->name);
 256
 257   desc->allocated += pool->elt_size;
 258   desc->current += pool->elt_size;
 259   if (desc->peak < desc->current)
 260     desc->peak = desc->current;
 261 #endif
 262
 263   gcc_checking_assert (pool);
 264
 265   /* If there are no more free elements, make some more!.  */
 266   if (!pool->returned_free_list)
 267     {
 268       char *block;
 269       if (!pool->virgin_elts_remaining)
 270         {
 271           alloc_pool_list block_header;
 272
 273           /* Make the block.  */
 274           block = XNEWVEC (char, pool->block_size);
 275           block_header = (alloc_pool_list) block;
 276           block += align_eight (sizeof (struct alloc_pool_list_def));
 277
 278           /* Throw it on the block list.  */
 279           block_header->next = pool->block_list;
 280           pool->block_list = block_header;
 281
 282           /* Make the block available for allocation.  */
 283           pool->virgin_free_list = block;
 284           pool->virgin_elts_remaining = pool->elts_per_block;
 285
 286           /* Also update the number of elements we have free/allocated, and
 287              increment the allocated block count.  */
 288           pool->elts_allocated += pool->elts_per_block;
 289           pool->elts_free += pool->elts_per_block;
 290           pool->blocks_allocated += 1;
 291         }
 292
 293
 294       /* We now know that we can take the first elt off the virgin list and
 295          put it on the returned list. */
 296       block = pool->virgin_free_list;
 297       header = (alloc_pool_list) USER_PTR_FROM_ALLOCATION_OBJECT_PTR (block);
 298       header->next = NULL;
 299 #ifdef ENABLE_CHECKING
 300       /* Mark the element to be free.  */
 301       ((allocation_object *) block)->id = 0;
 302 #endif
 303       pool->returned_free_list = header;
 304       pool->virgin_free_list += pool->elt_size;
 305       pool->virgin_elts_remaining--;
 306
 307     }
 308
 309   /* Pull the first free element from the free list, and return it.  */
 310   header = pool->returned_free_list;
 311   pool->returned_free_list = header->next;
 312   pool->elts_free--;
 313
 314 #ifdef ENABLE_CHECKING
 315   /* Set the ID for element.  */
 316   ALLOCATION_OBJECT_PTR_FROM_USER_PTR (header)->id = pool->id;
 317 #endif
 318
 319   return ((void *) header);
 320 }
 321
 322 /* Puts PTR back on POOL's free list.  */
 323 void
 324 pool_free (alloc_pool pool, void *ptr)
 325 {
 326   alloc_pool_list header;
 327 #ifdef GATHER_STATISTICS
 328   struct alloc_pool_descriptor *desc = alloc_pool_descriptor (pool->name);
 329 #endif
 330
 331
 332 #ifdef ENABLE_CHECKING
 333   gcc_assert (ptr
 334               /* Check if we free more than we allocated, which is Bad (TM).  */
 335               && pool->elts_free < pool->elts_allocated
 336               /* Check whether the PTR was allocated from POOL.  */
 337               && pool->id == ALLOCATION_OBJECT_PTR_FROM_USER_PTR (ptr)->id);
 338
 339   memset (ptr, 0xaf, pool->elt_size - offsetof (allocation_object, u.data));
 340
 341   /* Mark the element to be free.  */
 342   ALLOCATION_OBJECT_PTR_FROM_USER_PTR (ptr)->id = 0;
 343 #else
 344 #endif
 345
 346   header = (alloc_pool_list) ptr;
 347   header->next = pool->returned_free_list;
 348   pool->returned_free_list = header;
 349   pool->elts_free++;
 350
 351 #ifdef GATHER_STATISTICS
 352   desc->current -= pool->elt_size;
 353 #endif
 354
 355 }
 356 /* Output per-alloc_pool statistics.  */
 357 #ifdef GATHER_STATISTICS
 358
 359 /* Used to accumulate statistics about alloc_pool sizes.  */
 360 struct output_info
 361 {
 362   unsigned long total_created;
 363   unsigned long total_allocated;
 364 };
 365
 366 /* Called via htab_traverse.  Output alloc_pool descriptor pointed out by SLOT
 367    and update statistics.  */
 368 static int
 369 print_statistics (void **slot, void *b)
 370 {
 371   struct alloc_pool_descriptor *d = (struct alloc_pool_descriptor *) *slot;
 372   struct output_info *i = (struct output_info *) b;
 373
 374   if (d->allocated)
 375     {
 376       fprintf (stderr, "%-22s %6d %10lu %10lu(%10lu) %10lu(%10lu) %10lu(%10lu)\n", d->name,
 377                d->elt_size, d->created, d->allocated, d->allocated / d->elt_size,
 378                d->peak, d->peak / d->elt_size,
 379                d->current, d->current / d->elt_size);
 380       i->total_allocated += d->allocated;
 381       i->total_created += d->created;
 382     }
 383   return 1;
 384 }
 385 #endif
 386
 387 /* Output per-alloc_pool memory usage statistics.  */
 388 void
 389 dump_alloc_pool_statistics (void)
 390 {
 391 #ifdef GATHER_STATISTICS
 392   struct output_info info;
 393
 394   if (!alloc_pool_hash)
 395     return;
 396
 397   fprintf (stderr, "\nAlloc-pool Kind         Elt size  Pools  Allocated (elts)            Peak (elts)            Leak (elts)\n");
 398   fprintf (stderr, "--------------------------------------------------------------------------------------------------------------\n");
 399   info.total_created = 0;
 400   info.total_allocated = 0;
 401   htab_traverse (alloc_pool_hash, print_statistics, &info);
 402   fprintf (stderr, "--------------------------------------------------------------------------------------------------------------\n");
 403   fprintf (stderr, "%-22s           %7lu %10lu\n",
 404            "Total", info.total_created, info.total_allocated);
 405   fprintf (stderr, "--------------------------------------------------------------------------------------------------------------\n");
 406 #endif
 407 }