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    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 /* Frees the alloc_pool, if it is empty and zero *POOL in this case.  */
 211 void
 212 free_alloc_pool_if_empty (alloc_pool *pool)
 213 {
 214   if ((*pool)->elts_free == (*pool)->elts_allocated)
 215     {
 216       free_alloc_pool (*pool);
 217       *pool = NULL;
 218     }
 219 }
 220
 221 /* Allocates one element from the pool specified.  */
 222 void *
 223 pool_alloc (alloc_pool pool)
 224 {
 225   alloc_pool_list header;
 226   char *block;
 227 #ifdef GATHER_STATISTICS
 228   struct alloc_pool_descriptor *desc = alloc_pool_descriptor (pool->name);
 229
 230   desc->allocated+=pool->elt_size;
 231 #endif
 232
 233   gcc_assert (pool);
 234
 235   /* If there are no more free elements, make some more!.  */
 236   if (!pool->free_list)
 237     {
 238       size_t i;
 239       alloc_pool_list block_header;
 240
 241       /* Make the block.  */
 242       block = XNEWVEC (char, pool->block_size);
 243       block_header = (alloc_pool_list) block;
 244       block += align_eight (sizeof (struct alloc_pool_list_def));
 245 #ifdef GATHER_STATISTICS
 246       desc->current += pool->block_size;
 247       if (desc->peak < desc->current)
 248         desc->peak = desc->current;
 249 #endif
 250
 251       /* Throw it on the block list.  */
 252       block_header->next = pool->block_list;
 253       pool->block_list = block_header;
 254
 255       /* Now put the actual block pieces onto the free list.  */
 256       for (i = 0; i < pool->elts_per_block; i++, block += pool->elt_size)
 257       {
 258 #ifdef ENABLE_CHECKING
 259         /* Mark the element to be free.  */
 260         ((allocation_object *) block)->id = 0;
 261 #endif
 262         header = (alloc_pool_list) USER_PTR_FROM_ALLOCATION_OBJECT_PTR (block);
 263         header->next = pool->free_list;
 264         pool->free_list = header;
 265       }
 266       /* Also update the number of elements we have free/allocated, and
 267          increment the allocated block count.  */
 268       pool->elts_allocated += pool->elts_per_block;
 269       pool->elts_free += pool->elts_per_block;
 270       pool->blocks_allocated += 1;
 271     }
 272
 273   /* Pull the first free element from the free list, and return it.  */
 274   header = pool->free_list;
 275   pool->free_list = header->next;
 276   pool->elts_free--;
 277
 278 #ifdef ENABLE_CHECKING
 279   /* Set the ID for element.  */
 280   ALLOCATION_OBJECT_PTR_FROM_USER_PTR (header)->id = pool->id;
 281 #endif
 282
 283   return ((void *) header);
 284 }
 285
 286 /* Puts PTR back on POOL's free list.  */
 287 void
 288 pool_free (alloc_pool pool, void *ptr)
 289 {
 290   alloc_pool_list header;
 291
 292   gcc_assert (ptr);
 293
 294 #ifdef ENABLE_CHECKING
 295   memset (ptr, 0xaf, pool->elt_size - offsetof (allocation_object, u.data));
 296
 297   /* Check whether the PTR was allocated from POOL.  */
 298   gcc_assert (pool->id == ALLOCATION_OBJECT_PTR_FROM_USER_PTR (ptr)->id);
 299
 300   /* Mark the element to be free.  */
 301   ALLOCATION_OBJECT_PTR_FROM_USER_PTR (ptr)->id = 0;
 302 #else
 303   /* Check if we free more than we allocated, which is Bad (TM).  */
 304   gcc_assert (pool->elts_free < pool->elts_allocated);
 305 #endif
 306
 307   header = (alloc_pool_list) ptr;
 308   header->next = pool->free_list;
 309   pool->free_list = header;
 310   pool->elts_free++;
 311 }
 312 /* Output per-alloc_pool statistics.  */
 313 #ifdef GATHER_STATISTICS
 314
 315 /* Used to accumulate statistics about alloc_pool sizes.  */
 316 struct output_info
 317 {
 318   int count;
 319   int size;
 320 };
 321
 322 /* Called via htab_traverse.  Output alloc_pool descriptor pointed out by SLOT
 323    and update statistics.  */
 324 static int
 325 print_statistics (void **slot, void *b)
 326 {
 327   struct alloc_pool_descriptor *d = (struct alloc_pool_descriptor *) *slot;
 328   struct output_info *i = (struct output_info *) b;
 329
 330   if (d->allocated)
 331     {
 332       fprintf (stderr, "%-21s %6d %10d %10d %10d\n", d->name,
 333                d->created, d->allocated, d->peak, d->current);
 334       i->size += d->allocated;
 335       i->count += d->created;
 336     }
 337   return 1;
 338 }
 339 #endif
 340
 341 /* Output per-alloc_pool memory usage statistics.  */
 342 void
 343 dump_alloc_pool_statistics (void)
 344 {
 345 #ifdef GATHER_STATISTICS
 346   struct output_info info;
 347
 348   if (!alloc_pool_hash)
 349     return;
 350
 351   fprintf (stderr, "\nAlloc-pool Kind        Pools  Allocated      Peak        Leak\n");
 352   fprintf (stderr, "-------------------------------------------------------------\n");
 353   info.count = 0;
 354   info.size = 0;
 355   htab_traverse (alloc_pool_hash, print_statistics, &info);
 356   fprintf (stderr, "-------------------------------------------------------------\n");
 357   fprintf (stderr, "%-20s %7d %10d\n",
 358            "Total", info.count, info.size);
 359   fprintf (stderr, "-------------------------------------------------------------\n");
 360 #endif
 361 }