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, 2007
   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->returned_free_list = NULL;
 165   pool->virgin_free_list = NULL;
 166   pool->virgin_elts_remaining = 0;
 167   pool->elts_allocated = 0;
 168   pool->elts_free = 0;
 169   pool->blocks_allocated = 0;
 170   pool->block_list = NULL;
 171
 172 #ifdef ENABLE_CHECKING
 173   /* Increase the last used ID and use it for this pool.
 174      ID == 0 is used for free elements of pool so skip it.  */
 175   last_id++;
 176   if (last_id == 0)
 177     last_id++;
 178
 179   pool->id = last_id;
 180 #endif
 181
 182   return (pool);
 183 }
 184
 185 /* Free all memory allocated for the given memory pool.  */
 186 void
 187 free_alloc_pool (alloc_pool pool)
 188 {
 189   alloc_pool_list block, next_block;
 190 #ifdef GATHER_STATISTICS
 191   struct alloc_pool_descriptor *desc = alloc_pool_descriptor (pool->name);
 192 #endif
 193
 194   gcc_assert (pool);
 195
 196   /* Free each block allocated to the pool.  */
 197   for (block = pool->block_list; block != NULL; block = next_block)
 198     {
 199       next_block = block->next;
 200       free (block);
 201 #ifdef GATHER_STATISTICS
 202       desc->current -= pool->block_size;
 203 #endif
 204     }
 205 #ifdef ENABLE_CHECKING
 206   memset (pool, 0xaf, sizeof (*pool));
 207 #endif
 208   /* Lastly, free the pool.  */
 209   free (pool);
 210 }
 211
 212 /* Frees the alloc_pool, if it is empty and zero *POOL in this case.  */
 213 void
 214 free_alloc_pool_if_empty (alloc_pool *pool)
 215 {
 216   if ((*pool)->elts_free == (*pool)->elts_allocated)
 217     {
 218       free_alloc_pool (*pool);
 219       *pool = NULL;
 220     }
 221 }
 222
 223 /* Allocates one element from the pool specified.  */
 224 void *
 225 pool_alloc (alloc_pool pool)
 226 {
 227   alloc_pool_list header;
 228 #ifdef GATHER_STATISTICS
 229   struct alloc_pool_descriptor *desc = alloc_pool_descriptor (pool->name);
 230
 231   desc->allocated+=pool->elt_size;
 232 #endif
 233
 234   gcc_assert (pool);
 235
 236   /* If there are no more free elements, make some more!.  */
 237   if (!pool->returned_free_list)
 238     {
 239       char *block;
 240       if (!pool->virgin_elts_remaining)
 241         {
 242           alloc_pool_list block_header;
 243
 244           /* Make the block.  */
 245           block = XNEWVEC (char, pool->block_size);
 246           block_header = (alloc_pool_list) block;
 247           block += align_eight (sizeof (struct alloc_pool_list_def));
 248 #ifdef GATHER_STATISTICS
 249           desc->current += pool->block_size;
 250           if (desc->peak < desc->current)
 251             desc->peak = desc->current;
 252 #endif
 253
 254           /* Throw it on the block list.  */
 255           block_header->next = pool->block_list;
 256           pool->block_list = block_header;
 257
 258           /* Make the block available for allocation.  */
 259           pool->virgin_free_list = block;
 260           pool->virgin_elts_remaining = pool->elts_per_block;
 261
 262           /* Also update the number of elements we have free/allocated, and
 263              increment the allocated block count.  */
 264           pool->elts_allocated += pool->elts_per_block;
 265           pool->elts_free += pool->elts_per_block;
 266           pool->blocks_allocated += 1;
 267         }
 268
 269
 270       /* We now know that we can take the first elt off the virgin list and
 271          put it on the returned list. */
 272       block = pool->virgin_free_list;
 273       header = (alloc_pool_list) USER_PTR_FROM_ALLOCATION_OBJECT_PTR (block);
 274       header->next = NULL;
 275 #ifdef ENABLE_CHECKING
 276       /* Mark the element to be free.  */
 277       ((allocation_object *) block)->id = 0;
 278 #endif
 279       pool->returned_free_list = header;
 280       pool->virgin_free_list += pool->elt_size;
 281       pool->virgin_elts_remaining--;
 282
 283     }
 284
 285   /* Pull the first free element from the free list, and return it.  */
 286   header = pool->returned_free_list;
 287   pool->returned_free_list = header->next;
 288   pool->elts_free--;
 289
 290 #ifdef ENABLE_CHECKING
 291   /* Set the ID for element.  */
 292   ALLOCATION_OBJECT_PTR_FROM_USER_PTR (header)->id = pool->id;
 293 #endif
 294
 295   return ((void *) header);
 296 }
 297
 298 /* Puts PTR back on POOL's free list.  */
 299 void
 300 pool_free (alloc_pool pool, void *ptr)
 301 {
 302   alloc_pool_list header;
 303
 304   gcc_assert (ptr);
 305
 306 #ifdef ENABLE_CHECKING
 307   /* Check whether the PTR was allocated from POOL.  */
 308   gcc_assert (pool->id == ALLOCATION_OBJECT_PTR_FROM_USER_PTR (ptr)->id);
 309
 310   memset (ptr, 0xaf, pool->elt_size - offsetof (allocation_object, u.data));
 311
 312   /* Mark the element to be free.  */
 313   ALLOCATION_OBJECT_PTR_FROM_USER_PTR (ptr)->id = 0;
 314 #else
 315   /* Check if we free more than we allocated, which is Bad (TM).  */
 316   gcc_assert (pool->elts_free < pool->elts_allocated);
 317 #endif
 318
 319   header = (alloc_pool_list) ptr;
 320   header->next = pool->returned_free_list;
 321   pool->returned_free_list = header;
 322   pool->elts_free++;
 323 }
 324 /* Output per-alloc_pool statistics.  */
 325 #ifdef GATHER_STATISTICS
 326
 327 /* Used to accumulate statistics about alloc_pool sizes.  */
 328 struct output_info
 329 {
 330   int count;
 331   int size;
 332 };
 333
 334 /* Called via htab_traverse.  Output alloc_pool descriptor pointed out by SLOT
 335    and update statistics.  */
 336 static int
 337 print_statistics (void **slot, void *b)
 338 {
 339   struct alloc_pool_descriptor *d = (struct alloc_pool_descriptor *) *slot;
 340   struct output_info *i = (struct output_info *) b;
 341
 342   if (d->allocated)
 343     {
 344       fprintf (stderr, "%-21s %6d %10d %10d %10d\n", d->name,
 345                d->created, d->allocated, d->peak, d->current);
 346       i->size += d->allocated;
 347       i->count += d->created;
 348     }
 349   return 1;
 350 }
 351 #endif
 352
 353 /* Output per-alloc_pool memory usage statistics.  */
 354 void
 355 dump_alloc_pool_statistics (void)
 356 {
 357 #ifdef GATHER_STATISTICS
 358   struct output_info info;
 359
 360   if (!alloc_pool_hash)
 361     return;
 362
 363   fprintf (stderr, "\nAlloc-pool Kind        Pools  Allocated      Peak        Leak\n");
 364   fprintf (stderr, "-------------------------------------------------------------\n");
 365   info.count = 0;
 366   info.size = 0;
 367   htab_traverse (alloc_pool_hash, print_statistics, &info);
 368   fprintf (stderr, "-------------------------------------------------------------\n");
 369   fprintf (stderr, "%-20s %7d %10d\n",
 370            "Total", info.count, info.size);
 371   fprintf (stderr, "-------------------------------------------------------------\n");
 372 #endif
 373 }