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 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       char *align_p;
  46       HOST_WIDEST_INT align_i;
  47       long double align_ld;
  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.  */
  68 struct alloc_pool_descriptor
  69 {
  70   const char *name;
  71   int allocated;
  72   int created;
  73   int peak;
  74   int current;
  75 };
  76
  77 /* Hashtable mapping alloc_pool names to descriptors.  */
  78 static htab_t alloc_pool_hash;
  79
  80 /* Hashtable helpers.  */
  81 static hashval_t
  82 hash_descriptor (const void *p)
  83 {
  84   const struct alloc_pool_descriptor *d = p;
  85   return htab_hash_pointer (d->name);
  86 }
  87 static int
  88 eq_descriptor (const void *p1, const void *p2)
  89 {
  90   const struct alloc_pool_descriptor *d = p1;
  91   return d->name == p2;
  92 }
  93
  94 /* For given name, return descriptor, create new if needed.  */
  95 static struct alloc_pool_descriptor *
  96 alloc_pool_descriptor (const char *name)
  97 {
  98   struct alloc_pool_descriptor **slot;
  99
 100   if (!alloc_pool_hash)
 101     alloc_pool_hash = htab_create (10, hash_descriptor, eq_descriptor, NULL);
 102
 103   slot = (struct alloc_pool_descriptor **)
 104     htab_find_slot_with_hash (alloc_pool_hash, name,
 105                               htab_hash_pointer (name),
 106                               1);
 107   if (*slot)
 108     return *slot;
 109   *slot = xcalloc (sizeof (**slot), 1);
 110   (*slot)->name = name;
 111   return *slot;
 112 }
 113 #endif
 114
 115 /* Create a pool of things of size SIZE, with NUM in each block we
 116    allocate.  */
 117
 118 alloc_pool
 119 create_alloc_pool (const char *name, size_t size, size_t num)
 120 {
 121   alloc_pool pool;
 122   size_t pool_size, header_size;
 123 #ifdef GATHER_STATISTICS
 124   struct alloc_pool_descriptor *desc;
 125 #endif
 126
 127   gcc_assert (name);
 128
 129   /* Make size large enough to store the list header.  */
 130   if (size < sizeof (alloc_pool_list))
 131     size = sizeof (alloc_pool_list);
 132
 133   /* Now align the size to a multiple of 4.  */
 134   size = align_eight (size);
 135
 136 #ifdef ENABLE_CHECKING
 137   /* Add the aligned size of ID.  */
 138   size += offsetof (allocation_object, u.data);
 139 #endif
 140
 141   /* Um, we can't really allocate 0 elements per block.  */
 142   gcc_assert (num);
 143
 144   /* Find the size of the pool structure, and the name.  */
 145   pool_size = sizeof (struct alloc_pool_def);
 146
 147   /* and allocate that much memory.  */
 148   pool = xmalloc (pool_size);
 149
 150   /* Now init the various pieces of our pool structure.  */
 151   pool->name = /*xstrdup (name)*/name;
 152 #ifdef GATHER_STATISTICS
 153   desc = alloc_pool_descriptor (name);
 154   desc->created++;
 155 #endif
 156   pool->elt_size = size;
 157   pool->elts_per_block = num;
 158
 159   /* List header size should be a multiple of 8.  */
 160   header_size = align_eight (sizeof (struct alloc_pool_list_def));
 161
 162   pool->block_size = (size * num) + header_size;
 163   pool->returned_free_list = NULL;
 164   pool->virgin_free_list = NULL;
 165   pool->virgin_elts_remaining = 0;
 166   pool->elts_allocated = 0;
 167   pool->elts_free = 0;
 168   pool->blocks_allocated = 0;
 169   pool->block_list = NULL;
 170
 171 #ifdef ENABLE_CHECKING
 172   /* Increase the last used ID and use it for this pool.
 173      ID == 0 is used for free elements of pool so skip it.  */
 174   last_id++;
 175   if (last_id == 0)
 176     last_id++;
 177
 178   pool->id = last_id;
 179 #endif
 180
 181   return (pool);
 182 }
 183
 184 /* Free all memory allocated for the given memory pool.  */
 185 void
 186 free_alloc_pool (alloc_pool pool)
 187 {
 188   alloc_pool_list block, next_block;
 189 #ifdef GATHER_STATISTICS
 190   struct alloc_pool_descriptor *desc = alloc_pool_descriptor (pool->name);
 191 #endif
 192
 193   gcc_assert (pool);
 194
 195   /* Free each block allocated to the pool.  */
 196   for (block = pool->block_list; block != NULL; block = next_block)
 197     {
 198       next_block = block->next;
 199       free (block);
 200 #ifdef GATHER_STATISTICS
 201       desc->current -= pool->block_size;
 202 #endif
 203     }
 204 #ifdef ENABLE_CHECKING
 205   memset (pool, 0xaf, sizeof (*pool));
 206 #endif
 207   /* Lastly, free the pool.  */
 208   free (pool);
 209 }
 210
 211 /* Frees the alloc_pool, if it is empty and zero *POOL in this case.  */
 212 void
 213 free_alloc_pool_if_empty (alloc_pool *pool)
 214 {
 215   if ((*pool)->elts_free == (*pool)->elts_allocated)
 216     {
 217       free_alloc_pool (*pool);
 218       *pool = NULL;
 219     }
 220 }
 221
 222 /* Allocates one element from the pool specified.  */
 223 void *
 224 pool_alloc (alloc_pool pool)
 225 {
 226   alloc_pool_list header;
 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->returned_free_list)
 237     {
 238       char *block;
 239       if (!pool->virgin_elts_remaining)
 240         {
 241           alloc_pool_list block_header;
 242
 243           /* Make the block.  */
 244           block = XNEWVEC (char, pool->block_size);
 245           block_header = (alloc_pool_list) block;
 246           block += align_eight (sizeof (struct alloc_pool_list_def));
 247 #ifdef GATHER_STATISTICS
 248           desc->current += pool->block_size;
 249           if (desc->peak < desc->current)
 250             desc->peak = desc->current;
 251 #endif
 252
 253           /* Throw it on the block list.  */
 254           block_header->next = pool->block_list;
 255           pool->block_list = block_header;
 256
 257           /* Make the block available for allocation.  */
 258           pool->virgin_free_list = block;
 259           pool->virgin_elts_remaining = pool->elts_per_block;
 260
 261           /* Also update the number of elements we have free/allocated, and
 262              increment the allocated block count.  */
 263           pool->elts_allocated += pool->elts_per_block;
 264           pool->elts_free += pool->elts_per_block;
 265           pool->blocks_allocated += 1;
 266         }
 267
 268
 269       /* We now know that we can take the first elt off the virgin list and
 270          put it on the returned list. */
 271       block = pool->virgin_free_list;
 272       header = (alloc_pool_list) USER_PTR_FROM_ALLOCATION_OBJECT_PTR (block);
 273       header->next = NULL;
 274 #ifdef ENABLE_CHECKING
 275       /* Mark the element to be free.  */
 276       ((allocation_object *) block)->id = 0;
 277 #endif
 278       pool->returned_free_list = header;
 279       pool->virgin_free_list += pool->elt_size;
 280       pool->virgin_elts_remaining--;
 281
 282     }
 283
 284   /* Pull the first free element from the free list, and return it.  */
 285   header = pool->returned_free_list;
 286   pool->returned_free_list = header->next;
 287   pool->elts_free--;
 288
 289 #ifdef ENABLE_CHECKING
 290   /* Set the ID for element.  */
 291   ALLOCATION_OBJECT_PTR_FROM_USER_PTR (header)->id = pool->id;
 292 #endif
 293
 294   return ((void *) header);
 295 }
 296
 297 /* Puts PTR back on POOL's free list.  */
 298 void
 299 pool_free (alloc_pool pool, void *ptr)
 300 {
 301   alloc_pool_list header;
 302
 303   gcc_assert (ptr);
 304
 305 #ifdef ENABLE_CHECKING
 306   /* Check whether the PTR was allocated from POOL.  */
 307   gcc_assert (pool->id == ALLOCATION_OBJECT_PTR_FROM_USER_PTR (ptr)->id);
 308
 309   memset (ptr, 0xaf, pool->elt_size - offsetof (allocation_object, u.data));
 310
 311   /* Mark the element to be free.  */
 312   ALLOCATION_OBJECT_PTR_FROM_USER_PTR (ptr)->id = 0;
 313 #else
 314   /* Check if we free more than we allocated, which is Bad (TM).  */
 315   gcc_assert (pool->elts_free < pool->elts_allocated);
 316 #endif
 317
 318   header = (alloc_pool_list) ptr;
 319   header->next = pool->returned_free_list;
 320   pool->returned_free_list = header;
 321   pool->elts_free++;
 322 }
 323 /* Output per-alloc_pool statistics.  */
 324 #ifdef GATHER_STATISTICS
 325
 326 /* Used to accumulate statistics about alloc_pool sizes.  */
 327 struct output_info
 328 {
 329   int count;
 330   int size;
 331 };
 332
 333 /* Called via htab_traverse.  Output alloc_pool descriptor pointed out by SLOT
 334    and update statistics.  */
 335 static int
 336 print_statistics (void **slot, void *b)
 337 {
 338   struct alloc_pool_descriptor *d = (struct alloc_pool_descriptor *) *slot;
 339   struct output_info *i = (struct output_info *) b;
 340
 341   if (d->allocated)
 342     {
 343       fprintf (stderr, "%-21s %6d %10d %10d %10d\n", d->name,
 344                d->created, d->allocated, d->peak, d->current);
 345       i->size += d->allocated;
 346       i->count += d->created;
 347     }
 348   return 1;
 349 }
 350 #endif
 351
 352 /* Output per-alloc_pool memory usage statistics.  */
 353 void
 354 dump_alloc_pool_statistics (void)
 355 {
 356 #ifdef GATHER_STATISTICS
 357   struct output_info info;
 358
 359   if (!alloc_pool_hash)
 360     return;
 361
 362   fprintf (stderr, "\nAlloc-pool Kind        Pools  Allocated      Peak        Leak\n");
 363   fprintf (stderr, "-------------------------------------------------------------\n");
 364   info.count = 0;
 365   info.size = 0;
 366   htab_traverse (alloc_pool_hash, print_statistics, &info);
 367   fprintf (stderr, "-------------------------------------------------------------\n");
 368   fprintf (stderr, "%-20s %7d %10d\n",
 369            "Total", info.count, info.size);
 370   fprintf (stderr, "-------------------------------------------------------------\n");
 371 #endif
 372 }