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