gcc/ggc-common.c

   1 /* Simple garbage collection for the GNU compiler.
   2    Copyright (C) 1999, 2000, 2001, 2002, 2003
   3    Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 2, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING.  If not, write to the Free
  19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  20 02111-1307, USA.  */
  21
  22 /* Generic garbage collection (GC) functions and data, not specific to
  23    any particular GC implementation.  */
  24
  25 #include "config.h"
  26 #include "system.h"
  27 #include "coretypes.h"
  28 #include "hashtab.h"
  29 #include "ggc.h"
  30 #include "toplev.h"
  31 #include "params.h"
  32 #include "hosthooks.h"
  33
  34 #ifdef HAVE_SYS_RESOURCE_H
  35 # include <sys/resource.h>
  36 #endif
  37
  38 #ifdef HAVE_MMAP_FILE
  39 # include <sys/mman.h>
  40 # ifdef HAVE_MINCORE
  41 /* This is on Solaris.  */
  42 #  include <sys/types.h>
  43 # endif
  44 #endif
  45
  46 #ifndef MAP_FAILED
  47 # define MAP_FAILED ((void *)-1)
  48 #endif
  49
  50 #ifdef ENABLE_VALGRIND_CHECKING
  51 # ifdef HAVE_VALGRIND_MEMCHECK_H
  52 #  include <valgrind/memcheck.h>
  53 # elif defined HAVE_MEMCHECK_H
  54 #  include <memcheck.h>
  55 # else
  56 #  include <valgrind.h>
  57 # endif
  58 #else
  59 /* Avoid #ifdef:s when we can help it.  */
  60 #define VALGRIND_DISCARD(x)
  61 #endif
  62
  63 /* Statistics about the allocation.  */
  64 static ggc_statistics *ggc_stats;
  65
  66 struct traversal_state;
  67
  68 static int ggc_htab_delete (void **, void *);
  69 static hashval_t saving_htab_hash (const void *);
  70 static int saving_htab_eq (const void *, const void *);
  71 static int call_count (void **, void *);
  72 static int call_alloc (void **, void *);
  73 static int compare_ptr_data (const void *, const void *);
  74 static void relocate_ptrs (void *, void *);
  75 static void write_pch_globals (const struct ggc_root_tab * const *tab,
  76                                struct traversal_state *state);
  77 static double ggc_rlimit_bound (double);
  78
  79 /* Maintain global roots that are preserved during GC.  */
  80
  81 /* Process a slot of an htab by deleting it if it has not been marked.  */
  82
  83 static int
  84 ggc_htab_delete (void **slot, void *info)
  85 {
  86   const struct ggc_cache_tab *r = (const struct ggc_cache_tab *) info;
  87
  88   if (! (*r->marked_p) (*slot))
  89     htab_clear_slot (*r->base, slot);
  90   else
  91     (*r->cb) (*slot);
  92
  93   return 1;
  94 }
  95
  96 /* Iterate through all registered roots and mark each element.  */
  97
  98 void
  99 ggc_mark_roots (void)
 100 {
 101   const struct ggc_root_tab *const *rt;
 102   const struct ggc_root_tab *rti;
 103   const struct ggc_cache_tab *const *ct;
 104   const struct ggc_cache_tab *cti;
 105   size_t i;
 106
 107   for (rt = gt_ggc_deletable_rtab; *rt; rt++)
 108     for (rti = *rt; rti->base != NULL; rti++)
 109       memset (rti->base, 0, rti->stride);
 110
 111   for (rt = gt_ggc_rtab; *rt; rt++)
 112     for (rti = *rt; rti->base != NULL; rti++)
 113       for (i = 0; i < rti->nelt; i++)
 114         (*rti->cb)(*(void **)((char *)rti->base + rti->stride * i));
 115
 116   ggc_mark_stringpool ();
 117
 118   /* Now scan all hash tables that have objects which are to be deleted if
 119      they are not already marked.  */
 120   for (ct = gt_ggc_cache_rtab; *ct; ct++)
 121     for (cti = *ct; cti->base != NULL; cti++)
 122       if (*cti->base)
 123         {
 124           ggc_set_mark (*cti->base);
 125           htab_traverse_noresize (*cti->base, ggc_htab_delete, (void *) cti);
 126           ggc_set_mark ((*cti->base)->entries);
 127         }
 128 }
 129
 130 /* Allocate a block of memory, then clear it.  */
 131 void *
 132 ggc_alloc_cleared (size_t size)
 133 {
 134   void *buf = ggc_alloc (size);
 135   memset (buf, 0, size);
 136   return buf;
 137 }
 138
 139 /* Resize a block of memory, possibly re-allocating it.  */
 140 void *
 141 ggc_realloc (void *x, size_t size)
 142 {
 143   void *r;
 144   size_t old_size;
 145
 146   if (x == NULL)
 147     return ggc_alloc (size);
 148
 149   old_size = ggc_get_size (x);
 150   if (size <= old_size)
 151     {
 152       /* Mark the unwanted memory as unaccessible.  We also need to make
 153          the "new" size accessible, since ggc_get_size returns the size of
 154          the pool, not the size of the individually allocated object, the
 155          size which was previously made accessible.  Unfortunately, we
 156          don't know that previously allocated size.  Without that
 157          knowledge we have to lose some initialization-tracking for the
 158          old parts of the object.  An alternative is to mark the whole
 159          old_size as reachable, but that would lose tracking of writes
 160          after the end of the object (by small offsets).  Discard the
 161          handle to avoid handle leak.  */
 162       VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS ((char *) x + size,
 163                                                 old_size - size));
 164       VALGRIND_DISCARD (VALGRIND_MAKE_READABLE (x, size));
 165       return x;
 166     }
 167
 168   r = ggc_alloc (size);
 169
 170   /* Since ggc_get_size returns the size of the pool, not the size of the
 171      individually allocated object, we'd access parts of the old object
 172      that were marked invalid with the memcpy below.  We lose a bit of the
 173      initialization-tracking since some of it may be uninitialized.  */
 174   VALGRIND_DISCARD (VALGRIND_MAKE_READABLE (x, old_size));
 175
 176   memcpy (r, x, old_size);
 177
 178   /* The old object is not supposed to be used anymore.  */
 179   VALGRIND_DISCARD (VALGRIND_MAKE_NOACCESS (x, old_size));
 180
 181   return r;
 182 }
 183
 184 /* Like ggc_alloc_cleared, but performs a multiplication.  */
 185 void *
 186 ggc_calloc (size_t s1, size_t s2)
 187 {
 188   return ggc_alloc_cleared (s1 * s2);
 189 }
 190
 191 /* These are for splay_tree_new_ggc.  */
 192 void *
 193 ggc_splay_alloc (int sz, void *nl)
 194 {
 195   if (nl != NULL)
 196     abort ();
 197   return ggc_alloc (sz);
 198 }
 199
 200 void
 201 ggc_splay_dont_free (void * x ATTRIBUTE_UNUSED, void *nl)
 202 {
 203   if (nl != NULL)
 204     abort ();
 205 }
 206
 207 /* Print statistics that are independent of the collector in use.  */
 208 #define SCALE(x) ((unsigned long) ((x) < 1024*10 \
 209                   ? (x) \
 210                   : ((x) < 1024*1024*10 \
 211                      ? (x) / 1024 \
 212                      : (x) / (1024*1024))))
 213 #define LABEL(x) ((x) < 1024*10 ? ' ' : ((x) < 1024*1024*10 ? 'k' : 'M'))
 214
 215 void
 216 ggc_print_common_statistics (FILE *stream ATTRIBUTE_UNUSED,
 217                              ggc_statistics *stats)
 218 {
 219   /* Set the pointer so that during collection we will actually gather
 220      the statistics.  */
 221   ggc_stats = stats;
 222
 223   /* Then do one collection to fill in the statistics.  */
 224   ggc_collect ();
 225
 226   /* At present, we don't really gather any interesting statistics.  */
 227
 228   /* Don't gather statistics any more.  */
 229   ggc_stats = NULL;
 230 }
 231 \f
 232 /* Functions for saving and restoring GCable memory to disk.  */
 233
 234 static htab_t saving_htab;
 235
 236 struct ptr_data
 237 {
 238   void *obj;
 239   void *note_ptr_cookie;
 240   gt_note_pointers note_ptr_fn;
 241   gt_handle_reorder reorder_fn;
 242   size_t size;
 243   void *new_addr;
 244 };
 245
 246 #define POINTER_HASH(x) (hashval_t)((long)x >> 3)
 247
 248 /* Register an object in the hash table.  */
 249
 250 int
 251 gt_pch_note_object (void *obj, void *note_ptr_cookie,
 252                     gt_note_pointers note_ptr_fn)
 253 {
 254   struct ptr_data **slot;
 255
 256   if (obj == NULL || obj == (void *) 1)
 257     return 0;
 258
 259   slot = (struct ptr_data **)
 260     htab_find_slot_with_hash (saving_htab, obj, POINTER_HASH (obj),
 261                               INSERT);
 262   if (*slot != NULL)
 263     {
 264       if ((*slot)->note_ptr_fn != note_ptr_fn
 265           || (*slot)->note_ptr_cookie != note_ptr_cookie)
 266         abort ();
 267       return 0;
 268     }
 269
 270   *slot = xcalloc (sizeof (struct ptr_data), 1);
 271   (*slot)->obj = obj;
 272   (*slot)->note_ptr_fn = note_ptr_fn;
 273   (*slot)->note_ptr_cookie = note_ptr_cookie;
 274   if (note_ptr_fn == gt_pch_p_S)
 275     (*slot)->size = strlen (obj) + 1;
 276   else
 277     (*slot)->size = ggc_get_size (obj);
 278   return 1;
 279 }
 280
 281 /* Register an object in the hash table.  */
 282
 283 void
 284 gt_pch_note_reorder (void *obj, void *note_ptr_cookie,
 285                      gt_handle_reorder reorder_fn)
 286 {
 287   struct ptr_data *data;
 288
 289   if (obj == NULL || obj == (void *) 1)
 290     return;
 291
 292   data = htab_find_with_hash (saving_htab, obj, POINTER_HASH (obj));
 293   if (data == NULL
 294       || data->note_ptr_cookie != note_ptr_cookie)
 295     abort ();
 296
 297   data->reorder_fn = reorder_fn;
 298 }
 299
 300 /* Hash and equality functions for saving_htab, callbacks for htab_create.  */
 301
 302 static hashval_t
 303 saving_htab_hash (const void *p)
 304 {
 305   return POINTER_HASH (((struct ptr_data *)p)->obj);
 306 }
 307
 308 static int
 309 saving_htab_eq (const void *p1, const void *p2)
 310 {
 311   return ((struct ptr_data *)p1)->obj == p2;
 312 }
 313
 314 /* Handy state for the traversal functions.  */
 315
 316 struct traversal_state
 317 {
 318   FILE *f;
 319   struct ggc_pch_data *d;
 320   size_t count;
 321   struct ptr_data **ptrs;
 322   size_t ptrs_i;
 323 };
 324
 325 /* Callbacks for htab_traverse.  */
 326
 327 static int
 328 call_count (void **slot, void *state_p)
 329 {
 330   struct ptr_data *d = (struct ptr_data *)*slot;
 331   struct traversal_state *state = (struct traversal_state *)state_p;
 332
 333   ggc_pch_count_object (state->d, d->obj, d->size, d->note_ptr_fn == gt_pch_p_S);
 334   state->count++;
 335   return 1;
 336 }
 337
 338 static int
 339 call_alloc (void **slot, void *state_p)
 340 {
 341   struct ptr_data *d = (struct ptr_data *)*slot;
 342   struct traversal_state *state = (struct traversal_state *)state_p;
 343
 344   d->new_addr = ggc_pch_alloc_object (state->d, d->obj, d->size, d->note_ptr_fn == gt_pch_p_S);
 345   state->ptrs[state->ptrs_i++] = d;
 346   return 1;
 347 }
 348
 349 /* Callback for qsort.  */
 350
 351 static int
 352 compare_ptr_data (const void *p1_p, const void *p2_p)
 353 {
 354   struct ptr_data *p1 = *(struct ptr_data *const *)p1_p;
 355   struct ptr_data *p2 = *(struct ptr_data *const *)p2_p;
 356   return (((size_t)p1->new_addr > (size_t)p2->new_addr)
 357           - ((size_t)p1->new_addr < (size_t)p2->new_addr));
 358 }
 359
 360 /* Callbacks for note_ptr_fn.  */
 361
 362 static void
 363 relocate_ptrs (void *ptr_p, void *state_p)
 364 {
 365   void **ptr = (void **)ptr_p;
 366   struct traversal_state *state ATTRIBUTE_UNUSED
 367     = (struct traversal_state *)state_p;
 368   struct ptr_data *result;
 369
 370   if (*ptr == NULL || *ptr == (void *)1)
 371     return;
 372
 373   result = htab_find_with_hash (saving_htab, *ptr, POINTER_HASH (*ptr));
 374   if (result == NULL)
 375     abort ();
 376   *ptr = result->new_addr;
 377 }
 378
 379 /* Write out, after relocation, the pointers in TAB.  */
 380 static void
 381 write_pch_globals (const struct ggc_root_tab * const *tab,
 382                    struct traversal_state *state)
 383 {
 384   const struct ggc_root_tab *const *rt;
 385   const struct ggc_root_tab *rti;
 386   size_t i;
 387
 388   for (rt = tab; *rt; rt++)
 389     for (rti = *rt; rti->base != NULL; rti++)
 390       for (i = 0; i < rti->nelt; i++)
 391         {
 392           void *ptr = *(void **)((char *)rti->base + rti->stride * i);
 393           struct ptr_data *new_ptr;
 394           if (ptr == NULL || ptr == (void *)1)
 395             {
 396               if (fwrite (&ptr, sizeof (void *), 1, state->f)
 397                   != 1)
 398                 fatal_error ("can't write PCH file: %m");
 399             }
 400           else
 401             {
 402               new_ptr = htab_find_with_hash (saving_htab, ptr,
 403                                              POINTER_HASH (ptr));
 404               if (fwrite (&new_ptr->new_addr, sizeof (void *), 1, state->f)
 405                   != 1)
 406                 fatal_error ("can't write PCH file: %m");
 407             }
 408         }
 409 }
 410
 411 /* Hold the information we need to mmap the file back in.  */
 412
 413 struct mmap_info
 414 {
 415   size_t offset;
 416   size_t size;
 417   void *preferred_base;
 418 };
 419
 420 /* Write out the state of the compiler to F.  */
 421
 422 void
 423 gt_pch_save (FILE *f)
 424 {
 425   const struct ggc_root_tab *const *rt;
 426   const struct ggc_root_tab *rti;
 427   size_t i;
 428   struct traversal_state state;
 429   char *this_object = NULL;
 430   size_t this_object_size = 0;
 431   struct mmap_info mmi;
 432   size_t page_size = getpagesize();
 433
 434   gt_pch_save_stringpool ();
 435
 436   saving_htab = htab_create (50000, saving_htab_hash, saving_htab_eq, free);
 437
 438   for (rt = gt_ggc_rtab; *rt; rt++)
 439     for (rti = *rt; rti->base != NULL; rti++)
 440       for (i = 0; i < rti->nelt; i++)
 441         (*rti->pchw)(*(void **)((char *)rti->base + rti->stride * i));
 442
 443   for (rt = gt_pch_cache_rtab; *rt; rt++)
 444     for (rti = *rt; rti->base != NULL; rti++)
 445       for (i = 0; i < rti->nelt; i++)
 446         (*rti->pchw)(*(void **)((char *)rti->base + rti->stride * i));
 447
 448   /* Prepare the objects for writing, determine addresses and such.  */
 449   state.f = f;
 450   state.d = init_ggc_pch();
 451   state.count = 0;
 452   htab_traverse (saving_htab, call_count, &state);
 453
 454   mmi.size = ggc_pch_total_size (state.d);
 455
 456   /* Try to arrange things so that no relocation is necessary, but
 457      don't try very hard.  On most platforms, this will always work,
 458      and on the rest it's a lot of work to do better.
 459      (The extra work goes in HOST_HOOKS_GT_PCH_GET_ADDRESS and
 460      HOST_HOOKS_GT_PCH_USE_ADDRESS.)  */
 461   mmi.preferred_base = host_hooks.gt_pch_get_address (mmi.size);
 462
 463 #if HAVE_MMAP_FILE
 464   if (mmi.preferred_base == NULL)
 465     {
 466       mmi.preferred_base = mmap (NULL, mmi.size,
 467                                  PROT_READ | PROT_WRITE, MAP_PRIVATE,
 468                                  fileno (state.f), 0);
 469       if (mmi.preferred_base == (void *) MAP_FAILED)
 470         mmi.preferred_base = NULL;
 471       else
 472         munmap (mmi.preferred_base, mmi.size);
 473     }
 474 #endif /* HAVE_MMAP_FILE */
 475
 476   ggc_pch_this_base (state.d, mmi.preferred_base);
 477
 478   state.ptrs = xmalloc (state.count * sizeof (*state.ptrs));
 479   state.ptrs_i = 0;
 480   htab_traverse (saving_htab, call_alloc, &state);
 481   qsort (state.ptrs, state.count, sizeof (*state.ptrs), compare_ptr_data);
 482
 483   /* Write out all the scalar variables.  */
 484   for (rt = gt_pch_scalar_rtab; *rt; rt++)
 485     for (rti = *rt; rti->base != NULL; rti++)
 486       if (fwrite (rti->base, rti->stride, 1, f) != 1)
 487         fatal_error ("can't write PCH file: %m");
 488
 489   /* Write out all the global pointers, after translation.  */
 490   write_pch_globals (gt_ggc_rtab, &state);
 491   write_pch_globals (gt_pch_cache_rtab, &state);
 492
 493   ggc_pch_prepare_write (state.d, state.f);
 494
 495   /* Pad the PCH file so that the mmapped area starts on a page boundary.  */
 496   {
 497     long o;
 498     o = ftell (state.f) + sizeof (mmi);
 499     if (o == -1)
 500       fatal_error ("can't get position in PCH file: %m");
 501     mmi.offset = page_size - o % page_size;
 502     if (mmi.offset == page_size)
 503       mmi.offset = 0;
 504     mmi.offset += o;
 505   }
 506   if (fwrite (&mmi, sizeof (mmi), 1, state.f) != 1)
 507     fatal_error ("can't write PCH file: %m");
 508   if (mmi.offset != 0
 509       && fseek (state.f, mmi.offset, SEEK_SET) != 0)
 510     fatal_error ("can't write padding to PCH file: %m");
 511
 512   /* Actually write out the objects.  */
 513   for (i = 0; i < state.count; i++)
 514     {
 515       if (this_object_size < state.ptrs[i]->size)
 516         {
 517           this_object_size = state.ptrs[i]->size;
 518           this_object = xrealloc (this_object, this_object_size);
 519         }
 520       memcpy (this_object, state.ptrs[i]->obj, state.ptrs[i]->size);
 521       if (state.ptrs[i]->reorder_fn != NULL)
 522         state.ptrs[i]->reorder_fn (state.ptrs[i]->obj,
 523                                    state.ptrs[i]->note_ptr_cookie,
 524                                    relocate_ptrs, &state);
 525       state.ptrs[i]->note_ptr_fn (state.ptrs[i]->obj,
 526                                   state.ptrs[i]->note_ptr_cookie,
 527                                   relocate_ptrs, &state);
 528       ggc_pch_write_object (state.d, state.f, state.ptrs[i]->obj,
 529                             state.ptrs[i]->new_addr, state.ptrs[i]->size, state.ptrs[i]->note_ptr_fn == gt_pch_p_S);
 530       if (state.ptrs[i]->note_ptr_fn != gt_pch_p_S)
 531         memcpy (state.ptrs[i]->obj, this_object, state.ptrs[i]->size);
 532     }
 533   ggc_pch_finish (state.d, state.f);
 534   gt_pch_fixup_stringpool ();
 535
 536   free (state.ptrs);
 537   htab_delete (saving_htab);
 538 }
 539
 540 /* Read the state of the compiler back in from F.  */
 541
 542 void
 543 gt_pch_restore (FILE *f)
 544 {
 545   const struct ggc_root_tab *const *rt;
 546   const struct ggc_root_tab *rti;
 547   size_t i;
 548   struct mmap_info mmi;
 549   void *addr;
 550   bool needs_read;
 551
 552   /* Delete any deletable objects.  This makes ggc_pch_read much
 553      faster, as it can be sure that no GCable objects remain other
 554      than the ones just read in.  */
 555   for (rt = gt_ggc_deletable_rtab; *rt; rt++)
 556     for (rti = *rt; rti->base != NULL; rti++)
 557       memset (rti->base, 0, rti->stride);
 558
 559   /* Read in all the scalar variables.  */
 560   for (rt = gt_pch_scalar_rtab; *rt; rt++)
 561     for (rti = *rt; rti->base != NULL; rti++)
 562       if (fread (rti->base, rti->stride, 1, f) != 1)
 563         fatal_error ("can't read PCH file: %m");
 564
 565   /* Read in all the global pointers, in 6 easy loops.  */
 566   for (rt = gt_ggc_rtab; *rt; rt++)
 567     for (rti = *rt; rti->base != NULL; rti++)
 568       for (i = 0; i < rti->nelt; i++)
 569         if (fread ((char *)rti->base + rti->stride * i,
 570                    sizeof (void *), 1, f) != 1)
 571           fatal_error ("can't read PCH file: %m");
 572
 573   for (rt = gt_pch_cache_rtab; *rt; rt++)
 574     for (rti = *rt; rti->base != NULL; rti++)
 575       for (i = 0; i < rti->nelt; i++)
 576         if (fread ((char *)rti->base + rti->stride * i,
 577                    sizeof (void *), 1, f) != 1)
 578           fatal_error ("can't read PCH file: %m");
 579
 580   if (fread (&mmi, sizeof (mmi), 1, f) != 1)
 581     fatal_error ("can't read PCH file: %m");
 582
 583   if (host_hooks.gt_pch_use_address (mmi.preferred_base, mmi.size))
 584     {
 585 #if HAVE_MMAP_FILE
 586       void *mmap_result;
 587
 588       mmap_result = mmap (mmi.preferred_base, mmi.size,
 589                           PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_FIXED,
 590                           fileno (f), mmi.offset);
 591
 592       /* The file might not be mmap-able.  */
 593       needs_read = mmap_result == (void *) MAP_FAILED;
 594
 595       /* Sanity check for broken MAP_FIXED.  */
 596       if (! needs_read && mmap_result != mmi.preferred_base)
 597         abort ();
 598 #else
 599       needs_read = true;
 600 #endif
 601       addr = mmi.preferred_base;
 602     }
 603   else
 604     {
 605 #if HAVE_MMAP_FILE
 606       addr = mmap (mmi.preferred_base, mmi.size,
 607                    PROT_READ | PROT_WRITE, MAP_PRIVATE,
 608                    fileno (f), mmi.offset);
 609
 610 #if HAVE_MINCORE
 611       if (addr != mmi.preferred_base)
 612         {
 613           size_t page_size = getpagesize();
 614           char one_byte;
 615
 616           if (addr != (void *) MAP_FAILED)
 617             munmap (addr, mmi.size);
 618
 619           /* We really want to be mapped at mmi.preferred_base
 620              so we're going to resort to MAP_FIXED.  But before,
 621              make sure that we can do so without destroying a
 622              previously mapped area, by looping over all pages
 623              that would be affected by the fixed mapping.  */
 624           errno = 0;
 625
 626           for (i = 0; i < mmi.size; i+= page_size)
 627             if (mincore ((char *)mmi.preferred_base + i, page_size,
 628                          (void *)&one_byte) == -1
 629                 && errno == ENOMEM)
 630               continue; /* The page is not mapped.  */
 631             else
 632               break;
 633
 634           if (i >= mmi.size)
 635             addr = mmap (mmi.preferred_base, mmi.size,
 636                          PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_FIXED,
 637                          fileno (f), mmi.offset);
 638         }
 639 #endif /* HAVE_MINCORE */
 640
 641       needs_read = addr == (void *) MAP_FAILED;
 642
 643 #else /* HAVE_MMAP_FILE */
 644       needs_read = true;
 645 #endif /* HAVE_MMAP_FILE */
 646       if (needs_read)
 647         addr = xmalloc (mmi.size);
 648     }
 649
 650   if (needs_read)
 651     {
 652       if (fseek (f, mmi.offset, SEEK_SET) != 0
 653           || fread (&mmi, mmi.size, 1, f) != 1)
 654         fatal_error ("can't read PCH file: %m");
 655     }
 656   else if (fseek (f, mmi.offset + mmi.size, SEEK_SET) != 0)
 657     fatal_error ("can't read PCH file: %m");
 658
 659   ggc_pch_read (f, addr);
 660
 661   if (addr != mmi.preferred_base)
 662     {
 663       for (rt = gt_ggc_rtab; *rt; rt++)
 664         for (rti = *rt; rti->base != NULL; rti++)
 665           for (i = 0; i < rti->nelt; i++)
 666             {
 667               char **ptr = (char **)((char *)rti->base + rti->stride * i);
 668               if (*ptr != NULL)
 669                 *ptr += (size_t)addr - (size_t)mmi.preferred_base;
 670             }
 671
 672       for (rt = gt_pch_cache_rtab; *rt; rt++)
 673         for (rti = *rt; rti->base != NULL; rti++)
 674           for (i = 0; i < rti->nelt; i++)
 675             {
 676               char **ptr = (char **)((char *)rti->base + rti->stride * i);
 677               if (*ptr != NULL)
 678                 *ptr += (size_t)addr - (size_t)mmi.preferred_base;
 679             }
 680
 681       sorry ("had to relocate PCH");
 682     }
 683
 684   gt_pch_restore_stringpool ();
 685 }
 686
 687 /* Modify the bound based on rlimits.  Keep the smallest number found.  */
 688 static double
 689 ggc_rlimit_bound (double limit)
 690 {
 691 #if defined(HAVE_GETRLIMIT)
 692   struct rlimit rlim;
 693 # ifdef RLIMIT_RSS
 694   if (getrlimit (RLIMIT_RSS, &rlim) == 0
 695       && rlim.rlim_cur != (rlim_t) RLIM_INFINITY
 696       && rlim.rlim_cur < limit)
 697     limit = rlim.rlim_cur;
 698 # endif
 699 # ifdef RLIMIT_DATA
 700   if (getrlimit (RLIMIT_DATA, &rlim) == 0
 701       && rlim.rlim_cur != (rlim_t) RLIM_INFINITY
 702       && rlim.rlim_cur < limit)
 703     limit = rlim.rlim_cur;
 704 # endif
 705 # ifdef RLIMIT_AS
 706   if (getrlimit (RLIMIT_AS, &rlim) == 0
 707       && rlim.rlim_cur != (rlim_t) RLIM_INFINITY
 708       && rlim.rlim_cur < limit)
 709     limit = rlim.rlim_cur;
 710 # endif
 711 #endif /* HAVE_GETRLIMIT */
 712
 713   return limit;
 714 }
 715
 716 /* Heuristic to set a default for GGC_MIN_EXPAND.  */
 717 int
 718 ggc_min_expand_heuristic (void)
 719 {
 720   double min_expand = physmem_total();
 721
 722   /* Adjust for rlimits.  */
 723   min_expand = ggc_rlimit_bound (min_expand);
 724
 725   /* The heuristic is a percentage equal to 30% + 70%*(RAM/1GB), yielding
 726      a lower bound of 30% and an upper bound of 100% (when RAM >= 1GB).  */
 727   min_expand /= 1024*1024*1024;
 728   min_expand *= 70;
 729   min_expand = MIN (min_expand, 70);
 730   min_expand += 30;
 731
 732   return min_expand;
 733 }
 734
 735 /* Heuristic to set a default for GGC_MIN_HEAPSIZE.  */
 736 int
 737 ggc_min_heapsize_heuristic (void)
 738 {
 739   double min_heap_kbytes = physmem_total();
 740
 741   /* Adjust for rlimits.  */
 742   min_heap_kbytes = ggc_rlimit_bound (min_heap_kbytes);
 743
 744   min_heap_kbytes /= 1024; /* Convert to Kbytes.  */
 745
 746   /* The heuristic is RAM/8, with a lower bound of 4M and an upper
 747      bound of 128M (when RAM >= 1GB).  */
 748   min_heap_kbytes /= 8;
 749   min_heap_kbytes = MAX (min_heap_kbytes, 4 * 1024);
 750   min_heap_kbytes = MIN (min_heap_kbytes, 128 * 1024);
 751
 752   return min_heap_kbytes;
 753 }
 754
 755 void
 756 init_ggc_heuristics (void)
 757 {
 758 #if !defined ENABLE_GC_CHECKING && !defined ENABLE_GC_ALWAYS_COLLECT
 759   set_param_value ("ggc-min-expand", ggc_min_expand_heuristic());
 760   set_param_value ("ggc-min-heapsize", ggc_min_heapsize_heuristic());
 761 #endif
 762 }