boehm-gc/alloc.c

   1 /*
   2  * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
   3  * Copyright (c) 1991-1996 by Xerox Corporation.  All rights reserved.
   4  * Copyright (c) 1998 by Silicon Graphics.  All rights reserved.
   5  * Copyright (c) 1999 by Hewlett-Packard Company. All rights reserved.
   6  *
   7  * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
   8  * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
   9  *
  10  * Permission is hereby granted to use or copy this program
  11  * for any purpose,  provided the above notices are retained on all copies.
  12  * Permission to modify the code and to distribute modified code is granted,
  13  * provided the above notices are retained, and a notice that the code was
  14  * modified is included with the above copyright notice.
  15  *
  16  */
  17
  18
  19 # include "private/gc_priv.h"
  20
  21 # include <stdio.h>
  22 # if !defined(MACOS) && !defined(MSWINCE)
  23 #   include <signal.h>
  24 #   include <sys/types.h>
  25 # endif
  26
  27 /*
  28  * Separate free lists are maintained for different sized objects
  29  * up to MAXOBJSZ.
  30  * The call GC_allocobj(i,k) ensures that the freelist for
  31  * kind k objects of size i points to a non-empty
  32  * free list. It returns a pointer to the first entry on the free list.
  33  * In a single-threaded world, GC_allocobj may be called to allocate
  34  * an object of (small) size i as follows:
  35  *
  36  *            opp = &(GC_objfreelist[i]);
  37  *            if (*opp == 0) GC_allocobj(i, NORMAL);
  38  *            ptr = *opp;
  39  *            *opp = obj_link(ptr);
  40  *
  41  * Note that this is very fast if the free list is non-empty; it should
  42  * only involve the execution of 4 or 5 simple instructions.
  43  * All composite objects on freelists are cleared, except for
  44  * their first word.
  45  */
  46
  47 /*
  48  *  The allocator uses GC_allochblk to allocate large chunks of objects.
  49  * These chunks all start on addresses which are multiples of
  50  * HBLKSZ.   Each allocated chunk has an associated header,
  51  * which can be located quickly based on the address of the chunk.
  52  * (See headers.c for details.)
  53  * This makes it possible to check quickly whether an
  54  * arbitrary address corresponds to an object administered by the
  55  * allocator.
  56  */
  57
  58 word GC_non_gc_bytes = 0;  /* Number of bytes not intended to be collected */
  59
  60 word GC_gc_no = 0;
  61
  62 #ifndef SMALL_CONFIG
  63   int GC_incremental = 0;  /* By default, stop the world.       */
  64 #endif
  65
  66 int GC_parallel = FALSE;   /* By default, parallel GC is off.   */
  67
  68 int GC_full_freq = 19;     /* Every 20th collection is a full   */
  69                            /* collection, whether we need it    */
  70                            /* or not.                           */
  71
  72 GC_bool GC_need_full_gc = FALSE;
  73                            /* Need full GC do to heap growth.   */
  74
  75 #ifdef THREADS
  76   GC_bool GC_world_stopped = FALSE;
  77 # define IF_THREADS(x) x
  78 #else
  79 # define IF_THREADS(x)
  80 #endif
  81
  82 word GC_used_heap_size_after_full = 0;
  83
  84 char * GC_copyright[] =
  85 {"Copyright 1988,1989 Hans-J. Boehm and Alan J. Demers ",
  86 "Copyright (c) 1991-1995 by Xerox Corporation.  All rights reserved. ",
  87 "Copyright (c) 1996-1998 by Silicon Graphics.  All rights reserved. ",
  88 "Copyright (c) 1999-2001 by Hewlett-Packard Company.  All rights reserved. ",
  89 "THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY",
  90 " EXPRESSED OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.",
  91 "See source code for details." };
  92
  93 # include "version.h"
  94
  95 /* some more variables */
  96
  97 extern signed_word GC_mem_found;  /* Number of reclaimed longwords      */
  98                                   /* after garbage collection           */
  99
 100 GC_bool GC_dont_expand = 0;
 101
 102 word GC_free_space_divisor = 3;
 103
 104 extern GC_bool GC_collection_in_progress();
 105                 /* Collection is in progress, or was abandoned. */
 106
 107 int GC_never_stop_func GC_PROTO((void)) { return(0); }
 108
 109 unsigned long GC_time_limit = TIME_LIMIT;
 110
 111 CLOCK_TYPE GC_start_time;       /* Time at which we stopped world.      */
 112                                 /* used only in GC_timeout_stop_func.   */
 113
 114 int GC_n_attempts = 0;          /* Number of attempts at finishing      */
 115                                 /* collection within GC_time_limit.     */
 116
 117 #if defined(SMALL_CONFIG) || defined(NO_CLOCK)
 118 #   define GC_timeout_stop_func GC_never_stop_func
 119 #else
 120   int GC_timeout_stop_func GC_PROTO((void))
 121   {
 122     CLOCK_TYPE current_time;
 123     static unsigned count = 0;
 124     unsigned long time_diff;
 125
 126     if ((count++ & 3) != 0) return(0);
 127     GET_TIME(current_time);
 128     time_diff = MS_TIME_DIFF(current_time,GC_start_time);
 129     if (time_diff >= GC_time_limit) {
 130 #       ifdef CONDPRINT
 131           if (GC_print_stats) {
 132             GC_printf0("Abandoning stopped marking after ");
 133             GC_printf1("%lu msecs", (unsigned long)time_diff);
 134             GC_printf1("(attempt %ld)\n", (unsigned long) GC_n_attempts);
 135           }
 136 #       endif
 137         return(1);
 138     }
 139     return(0);
 140   }
 141 #endif /* !SMALL_CONFIG */
 142
 143 /* Return the minimum number of words that must be allocated between    */
 144 /* collections to amortize the collection cost.                         */
 145 static word min_words_allocd()
 146 {
 147 #   ifdef THREADS
 148         /* We punt, for now. */
 149         register signed_word stack_size = 10000;
 150 #   else
 151         int dummy;
 152         register signed_word stack_size = (ptr_t)(&dummy) - GC_stackbottom;
 153 #   endif
 154     word total_root_size;           /* includes double stack size,      */
 155                                     /* since the stack is expensive     */
 156                                     /* to scan.                         */
 157     word scan_size;             /* Estimate of memory to be scanned     */
 158                                 /* during normal GC.                    */
 159
 160     if (stack_size < 0) stack_size = -stack_size;
 161     total_root_size = 2 * stack_size + GC_root_size;
 162     scan_size = BYTES_TO_WORDS(GC_heapsize - GC_large_free_bytes
 163                                + (GC_large_free_bytes >> 2)
 164                                    /* use a bit more of large empty heap */
 165                                + total_root_size);
 166     if (TRUE_INCREMENTAL) {
 167         return scan_size / (2 * GC_free_space_divisor);
 168     } else {
 169         return scan_size / GC_free_space_divisor;
 170     }
 171 }
 172
 173 /* Return the number of words allocated, adjusted for explicit storage  */
 174 /* management, etc..  This number is used in deciding when to trigger   */
 175 /* collections.                                                         */
 176 word GC_adj_words_allocd()
 177 {
 178     register signed_word result;
 179     register signed_word expl_managed =
 180                 BYTES_TO_WORDS((long)GC_non_gc_bytes
 181                                 - (long)GC_non_gc_bytes_at_gc);
 182
 183     /* Don't count what was explicitly freed, or newly allocated for    */
 184     /* explicit management.  Note that deallocating an explicitly       */
 185     /* managed object should not alter result, assuming the client      */
 186     /* is playing by the rules.                                         */
 187     result = (signed_word)GC_words_allocd
 188              - (signed_word)GC_mem_freed
 189              + (signed_word)GC_finalizer_mem_freed - expl_managed;
 190     if (result > (signed_word)GC_words_allocd) {
 191         result = GC_words_allocd;
 192         /* probably client bug or unfortunate scheduling */
 193     }
 194     result += GC_words_finalized;
 195         /* We count objects enqueued for finalization as though they    */
 196         /* had been reallocated this round. Finalization is user        */
 197         /* visible progress.  And if we don't count this, we have       */
 198         /* stability problems for programs that finalize all objects.   */
 199     result += GC_words_wasted;
 200         /* This doesn't reflect useful work.  But if there is lots of   */
 201         /* new fragmentation, the same is probably true of the heap,    */
 202         /* and the collection will be correspondingly cheaper.          */
 203     if (result < (signed_word)(GC_words_allocd >> 3)) {
 204         /* Always count at least 1/8 of the allocations.  We don't want */
 205         /* to collect too infrequently, since that would inhibit        */
 206         /* coalescing of free storage blocks.                           */
 207         /* This also makes us partially robust against client bugs.     */
 208         return(GC_words_allocd >> 3);
 209     } else {
 210         return(result);
 211     }
 212 }
 213
 214
 215 /* Clear up a few frames worth of garbage left at the top of the stack. */
 216 /* This is used to prevent us from accidentally treating garbade left   */
 217 /* on the stack by other parts of the collector as roots.  This         */
 218 /* differs from the code in misc.c, which actually tries to keep the    */
 219 /* stack clear of long-lived, client-generated garbage.                 */
 220 void GC_clear_a_few_frames()
 221 {
 222 #   define NWORDS 64
 223     word frames[NWORDS];
 224     register int i;
 225
 226     for (i = 0; i < NWORDS; i++) frames[i] = 0;
 227 }
 228
 229 /* Heap size at which we need a collection to avoid expanding past      */
 230 /* limits used by blacklisting.                                         */
 231 static word GC_collect_at_heapsize = (word)(-1);
 232
 233 /* Have we allocated enough to amortize a collection? */
 234 GC_bool GC_should_collect()
 235 {
 236     return(GC_adj_words_allocd() >= min_words_allocd()
 237            || GC_heapsize >= GC_collect_at_heapsize);
 238 }
 239
 240
 241 void GC_notify_full_gc()
 242 {
 243     if (GC_start_call_back != (void (*) GC_PROTO((void)))0) {
 244         (*GC_start_call_back)();
 245     }
 246 }
 247
 248 GC_bool GC_is_full_gc = FALSE;
 249
 250 /*
 251  * Initiate a garbage collection if appropriate.
 252  * Choose judiciously
 253  * between partial, full, and stop-world collections.
 254  * Assumes lock held, signals disabled.
 255  */
 256 void GC_maybe_gc()
 257 {
 258     static int n_partial_gcs = 0;
 259
 260     if (GC_should_collect()) {
 261         if (!GC_incremental) {
 262             GC_gcollect_inner();
 263             n_partial_gcs = 0;
 264             return;
 265         } else {
 266 #         ifdef PARALLEL_MARK
 267             GC_wait_for_reclaim();
 268 #         endif
 269           if (GC_need_full_gc || n_partial_gcs >= GC_full_freq) {
 270 #           ifdef CONDPRINT
 271               if (GC_print_stats) {
 272                 GC_printf2(
 273                   "***>Full mark for collection %lu after %ld allocd bytes\n",
 274                   (unsigned long) GC_gc_no+1,
 275                   (long)WORDS_TO_BYTES(GC_words_allocd));
 276               }
 277 #           endif
 278             GC_promote_black_lists();
 279             (void)GC_reclaim_all((GC_stop_func)0, TRUE);
 280             GC_clear_marks();
 281             n_partial_gcs = 0;
 282             GC_notify_full_gc();
 283             GC_is_full_gc = TRUE;
 284           } else {
 285             n_partial_gcs++;
 286           }
 287         }
 288         /* We try to mark with the world stopped.       */
 289         /* If we run out of time, this turns into       */
 290         /* incremental marking.                 */
 291 #       ifndef NO_CLOCK
 292           if (GC_time_limit != GC_TIME_UNLIMITED) { GET_TIME(GC_start_time); }
 293 #       endif
 294         if (GC_stopped_mark(GC_time_limit == GC_TIME_UNLIMITED?
 295                             GC_never_stop_func : GC_timeout_stop_func)) {
 296 #           ifdef SAVE_CALL_CHAIN
 297                 GC_save_callers(GC_last_stack);
 298 #           endif
 299             GC_finish_collection();
 300         } else {
 301             if (!GC_is_full_gc) {
 302                 /* Count this as the first attempt */
 303                 GC_n_attempts++;
 304             }
 305         }
 306     }
 307 }
 308
 309
 310 /*
 311  * Stop the world garbage collection.  Assumes lock held, signals disabled.
 312  * If stop_func is not GC_never_stop_func, then abort if stop_func returns TRUE.
 313  * Return TRUE if we successfully completed the collection.
 314  */
 315 GC_bool GC_try_to_collect_inner(stop_func)
 316 GC_stop_func stop_func;
 317 {
 318 #   ifdef CONDPRINT
 319         CLOCK_TYPE start_time, current_time;
 320 #   endif
 321     if (GC_dont_gc) return FALSE;
 322     if (GC_incremental && GC_collection_in_progress()) {
 323 #   ifdef CONDPRINT
 324       if (GC_print_stats) {
 325         GC_printf0(
 326             "GC_try_to_collect_inner: finishing collection in progress\n");
 327       }
 328 #   endif /* CONDPRINT */
 329       /* Just finish collection already in progress.    */
 330         while(GC_collection_in_progress()) {
 331             if (stop_func()) return(FALSE);
 332             GC_collect_a_little_inner(1);
 333         }
 334     }
 335     if (stop_func == GC_never_stop_func) GC_notify_full_gc();
 336 #   ifdef CONDPRINT
 337       if (GC_print_stats) {
 338         if (GC_print_stats) GET_TIME(start_time);
 339         GC_printf2(
 340            "Initiating full world-stop collection %lu after %ld allocd bytes\n",
 341            (unsigned long) GC_gc_no+1,
 342            (long)WORDS_TO_BYTES(GC_words_allocd));
 343       }
 344 #   endif
 345     GC_promote_black_lists();
 346     /* Make sure all blocks have been reclaimed, so sweep routines      */
 347     /* don't see cleared mark bits.                                     */
 348     /* If we're guaranteed to finish, then this is unnecessary.         */
 349     /* In the find_leak case, we have to finish to guarantee that       */
 350     /* previously unmarked objects are not reported as leaks.           */
 351 #       ifdef PARALLEL_MARK
 352             GC_wait_for_reclaim();
 353 #       endif
 354         if ((GC_find_leak || stop_func != GC_never_stop_func)
 355             && !GC_reclaim_all(stop_func, FALSE)) {
 356             /* Aborted.  So far everything is still consistent. */
 357             return(FALSE);
 358         }
 359     GC_invalidate_mark_state();  /* Flush mark stack.   */
 360     GC_clear_marks();
 361 #   ifdef SAVE_CALL_CHAIN
 362         GC_save_callers(GC_last_stack);
 363 #   endif
 364     GC_is_full_gc = TRUE;
 365     if (!GC_stopped_mark(stop_func)) {
 366       if (!GC_incremental) {
 367         /* We're partially done and have no way to complete or use      */
 368         /* current work.  Reestablish invariants as cheaply as          */
 369         /* possible.                                                    */
 370         GC_invalidate_mark_state();
 371         GC_unpromote_black_lists();
 372       } /* else we claim the world is already still consistent.  We'll  */
 373         /* finish incrementally.                                        */
 374       return(FALSE);
 375     }
 376     GC_finish_collection();
 377 #   if defined(CONDPRINT)
 378       if (GC_print_stats) {
 379         GET_TIME(current_time);
 380         GC_printf1("Complete collection took %lu msecs\n",
 381                    MS_TIME_DIFF(current_time,start_time));
 382       }
 383 #   endif
 384     return(TRUE);
 385 }
 386
 387
 388
 389 /*
 390  * Perform n units of garbage collection work.  A unit is intended to touch
 391  * roughly GC_RATE pages.  Every once in a while, we do more than that.
 392  * This needa to be a fairly large number with our current incremental
 393  * GC strategy, since otherwise we allocate too much during GC, and the
 394  * cleanup gets expensive.
 395  */
 396 # define GC_RATE 10
 397 # define MAX_PRIOR_ATTEMPTS 1
 398         /* Maximum number of prior attempts at world stop marking       */
 399         /* A value of 1 means that we finish the second time, no matter */
 400         /* how long it takes.  Doesn't count the initial root scan      */
 401         /* for a full GC.                                               */
 402
 403 int GC_deficit = 0;     /* The number of extra calls to GC_mark_some    */
 404                         /* that we have made.                           */
 405
 406 void GC_collect_a_little_inner(n)
 407 int n;
 408 {
 409     register int i;
 410
 411     if (GC_dont_gc) return;
 412     if (GC_incremental && GC_collection_in_progress()) {
 413         for (i = GC_deficit; i < GC_RATE*n; i++) {
 414             if (GC_mark_some((ptr_t)0)) {
 415                 /* Need to finish a collection */
 416 #               ifdef SAVE_CALL_CHAIN
 417                     GC_save_callers(GC_last_stack);
 418 #               endif
 419 #               ifdef PARALLEL_MARK
 420                     GC_wait_for_reclaim();
 421 #               endif
 422                 if (GC_n_attempts < MAX_PRIOR_ATTEMPTS
 423                     && GC_time_limit != GC_TIME_UNLIMITED) {
 424                   GET_TIME(GC_start_time);
 425                   if (!GC_stopped_mark(GC_timeout_stop_func)) {
 426                     GC_n_attempts++;
 427                     break;
 428                   }
 429                 } else {
 430                   (void)GC_stopped_mark(GC_never_stop_func);
 431                 }
 432                 GC_finish_collection();
 433                 break;
 434             }
 435         }
 436         if (GC_deficit > 0) GC_deficit -= GC_RATE*n;
 437         if (GC_deficit < 0) GC_deficit = 0;
 438     } else {
 439         GC_maybe_gc();
 440     }
 441 }
 442
 443 int GC_collect_a_little GC_PROTO(())
 444 {
 445     int result;
 446     DCL_LOCK_STATE;
 447
 448     DISABLE_SIGNALS();
 449     LOCK();
 450     GC_collect_a_little_inner(1);
 451     result = (int)GC_collection_in_progress();
 452     UNLOCK();
 453     ENABLE_SIGNALS();
 454     if (!result && GC_debugging_started) GC_print_all_smashed();
 455     return(result);
 456 }
 457
 458 /*
 459  * Assumes lock is held, signals are disabled.
 460  * We stop the world.
 461  * If stop_func() ever returns TRUE, we may fail and return FALSE.
 462  * Increment GC_gc_no if we succeed.
 463  */
 464 GC_bool GC_stopped_mark(stop_func)
 465 GC_stop_func stop_func;
 466 {
 467     register int i;
 468     int dummy;
 469 #   if defined(PRINTTIMES) || defined(CONDPRINT)
 470         CLOCK_TYPE start_time, current_time;
 471 #   endif
 472
 473 #   ifdef PRINTTIMES
 474         GET_TIME(start_time);
 475 #   endif
 476 #   if defined(CONDPRINT) && !defined(PRINTTIMES)
 477         if (GC_print_stats) GET_TIME(start_time);
 478 #   endif
 479 #   if defined(REGISTER_LIBRARIES_EARLY)
 480         GC_cond_register_dynamic_libraries();
 481 #   endif
 482     STOP_WORLD();
 483     IF_THREADS(GC_world_stopped = TRUE);
 484 #   ifdef CONDPRINT
 485       if (GC_print_stats) {
 486         GC_printf1("--> Marking for collection %lu ",
 487                    (unsigned long) GC_gc_no + 1);
 488         GC_printf2("after %lu allocd bytes + %lu wasted bytes\n",
 489                    (unsigned long) WORDS_TO_BYTES(GC_words_allocd),
 490                    (unsigned long) WORDS_TO_BYTES(GC_words_wasted));
 491       }
 492 #   endif
 493 #   ifdef MAKE_BACK_GRAPH
 494       if (GC_print_back_height) {
 495         GC_build_back_graph();
 496       }
 497 #   endif
 498
 499     /* Mark from all roots.  */
 500         /* Minimize junk left in my registers and on the stack */
 501             GC_clear_a_few_frames();
 502             GC_noop(0,0,0,0,0,0);
 503         GC_initiate_gc();
 504         for(i = 0;;i++) {
 505             if ((*stop_func)()) {
 506 #                   ifdef CONDPRINT
 507                       if (GC_print_stats) {
 508                         GC_printf0("Abandoned stopped marking after ");
 509                         GC_printf1("%lu iterations\n",
 510                                    (unsigned long)i);
 511                       }
 512 #                   endif
 513                     GC_deficit = i; /* Give the mutator a chance. */
 514                     IF_THREADS(GC_world_stopped = FALSE);
 515                     START_WORLD();
 516                     return(FALSE);
 517             }
 518             if (GC_mark_some((ptr_t)(&dummy))) break;
 519         }
 520
 521     GC_gc_no++;
 522 #   ifdef PRINTSTATS
 523       GC_printf2("Collection %lu reclaimed %ld bytes",
 524                   (unsigned long) GC_gc_no - 1,
 525                   (long)WORDS_TO_BYTES(GC_mem_found));
 526 #   else
 527 #     ifdef CONDPRINT
 528         if (GC_print_stats) {
 529           GC_printf1("Collection %lu finished", (unsigned long) GC_gc_no - 1);
 530         }
 531 #     endif
 532 #   endif /* !PRINTSTATS */
 533 #   ifdef CONDPRINT
 534       if (GC_print_stats) {
 535         GC_printf1(" ---> heapsize = %lu bytes\n",
 536                    (unsigned long) GC_heapsize);
 537         /* Printf arguments may be pushed in funny places.  Clear the   */
 538         /* space.                                                       */
 539         GC_printf0("");
 540       }
 541 #   endif  /* CONDPRINT  */
 542
 543     /* Check all debugged objects for consistency */
 544         if (GC_debugging_started) {
 545             (*GC_check_heap)();
 546         }
 547
 548     IF_THREADS(GC_world_stopped = FALSE);
 549     START_WORLD();
 550 #   ifdef PRINTTIMES
 551         GET_TIME(current_time);
 552         GC_printf1("World-stopped marking took %lu msecs\n",
 553                    MS_TIME_DIFF(current_time,start_time));
 554 #   else
 555 #     ifdef CONDPRINT
 556         if (GC_print_stats) {
 557           GET_TIME(current_time);
 558           GC_printf1("World-stopped marking took %lu msecs\n",
 559                      MS_TIME_DIFF(current_time,start_time));
 560         }
 561 #     endif
 562 #   endif
 563     return(TRUE);
 564 }
 565
 566 /* Set all mark bits for the free list whose first entry is q   */
 567 #ifdef __STDC__
 568   void GC_set_fl_marks(ptr_t q)
 569 #else
 570   void GC_set_fl_marks(q)
 571   ptr_t q;
 572 #endif
 573 {
 574    ptr_t p;
 575    struct hblk * h, * last_h = 0;
 576    hdr *hhdr;
 577    int word_no;
 578
 579    for (p = q; p != 0; p = obj_link(p)){
 580         h = HBLKPTR(p);
 581         if (h != last_h) {
 582           last_h = h;
 583           hhdr = HDR(h);
 584         }
 585         word_no = (((word *)p) - ((word *)h));
 586         set_mark_bit_from_hdr(hhdr, word_no);
 587    }
 588 }
 589
 590 /* Clear all mark bits for the free list whose first entry is q */
 591 /* Decrement GC_mem_found by number of words on free list.      */
 592 #ifdef __STDC__
 593   void GC_clear_fl_marks(ptr_t q)
 594 #else
 595   void GC_clear_fl_marks(q)
 596   ptr_t q;
 597 #endif
 598 {
 599    ptr_t p;
 600    struct hblk * h, * last_h = 0;
 601    hdr *hhdr;
 602    int word_no;
 603
 604    for (p = q; p != 0; p = obj_link(p)){
 605         h = HBLKPTR(p);
 606         if (h != last_h) {
 607           last_h = h;
 608           hhdr = HDR(h);
 609         }
 610         word_no = (((word *)p) - ((word *)h));
 611         clear_mark_bit_from_hdr(hhdr, word_no);
 612 #       ifdef GATHERSTATS
 613             GC_mem_found -= hhdr -> hb_sz;
 614 #       endif
 615    }
 616 }
 617
 618 /* Finish up a collection.  Assumes lock is held, signals are disabled, */
 619 /* but the world is otherwise running.                                  */
 620 void GC_finish_collection()
 621 {
 622 #   ifdef PRINTTIMES
 623         CLOCK_TYPE start_time;
 624         CLOCK_TYPE finalize_time;
 625         CLOCK_TYPE done_time;
 626
 627         GET_TIME(start_time);
 628         finalize_time = start_time;
 629 #   endif
 630
 631 #   ifdef GATHERSTATS
 632         GC_mem_found = 0;
 633 #   endif
 634 #   if defined(LINUX) && defined(__ELF__) && !defined(SMALL_CONFIG)
 635         if (getenv("GC_PRINT_ADDRESS_MAP") != 0) {
 636           GC_print_address_map();
 637         }
 638 #   endif
 639     COND_DUMP;
 640     if (GC_find_leak) {
 641       /* Mark all objects on the free list.  All objects should be */
 642       /* marked when we're done.                                   */
 643         {
 644           register word size;           /* current object size          */
 645           int kind;
 646           ptr_t q;
 647
 648           for (kind = 0; kind < GC_n_kinds; kind++) {
 649             for (size = 1; size <= MAXOBJSZ; size++) {
 650               q = GC_obj_kinds[kind].ok_freelist[size];
 651               if (q != 0) GC_set_fl_marks(q);
 652             }
 653           }
 654         }
 655         GC_start_reclaim(TRUE);
 656           /* The above just checks; it doesn't really reclaim anything. */
 657     }
 658
 659     GC_finalize();
 660 #   ifdef STUBBORN_ALLOC
 661       GC_clean_changing_list();
 662 #   endif
 663
 664 #   ifdef PRINTTIMES
 665       GET_TIME(finalize_time);
 666 #   endif
 667
 668     if (GC_print_back_height) {
 669 #     ifdef MAKE_BACK_GRAPH
 670         GC_traverse_back_graph();
 671 #     else
 672 #       ifndef SMALL_CONFIG
 673           GC_err_printf0("Back height not available: "
 674                          "Rebuild collector with -DMAKE_BACK_GRAPH\n");
 675 #       endif
 676 #     endif
 677     }
 678
 679     /* Clear free list mark bits, in case they got accidentally marked   */
 680     /* (or GC_find_leak is set and they were intentionally marked).      */
 681     /* Also subtract memory remaining from GC_mem_found count.           */
 682     /* Note that composite objects on free list are cleared.             */
 683     /* Thus accidentally marking a free list is not a problem;  only     */
 684     /* objects on the list itself will be marked, and that's fixed here. */
 685       {
 686         register word size;             /* current object size          */
 687         register ptr_t q;       /* pointer to current object    */
 688         int kind;
 689
 690         for (kind = 0; kind < GC_n_kinds; kind++) {
 691           for (size = 1; size <= MAXOBJSZ; size++) {
 692             q = GC_obj_kinds[kind].ok_freelist[size];
 693             if (q != 0) GC_clear_fl_marks(q);
 694           }
 695         }
 696       }
 697
 698
 699 #   ifdef PRINTSTATS
 700         GC_printf1("Bytes recovered before sweep - f.l. count = %ld\n",
 701                   (long)WORDS_TO_BYTES(GC_mem_found));
 702 #   endif
 703     /* Reconstruct free lists to contain everything not marked */
 704         GC_start_reclaim(FALSE);
 705         if (GC_is_full_gc)  {
 706             GC_used_heap_size_after_full = USED_HEAP_SIZE;
 707             GC_need_full_gc = FALSE;
 708         } else {
 709             GC_need_full_gc =
 710                  BYTES_TO_WORDS(USED_HEAP_SIZE - GC_used_heap_size_after_full)
 711                  > min_words_allocd();
 712         }
 713
 714 #   ifdef PRINTSTATS
 715         GC_printf2(
 716                   "Immediately reclaimed %ld bytes in heap of size %lu bytes",
 717                   (long)WORDS_TO_BYTES(GC_mem_found),
 718                   (unsigned long)GC_heapsize);
 719 #       ifdef USE_MUNMAP
 720           GC_printf1("(%lu unmapped)", GC_unmapped_bytes);
 721 #       endif
 722         GC_printf2(
 723                 "\n%lu (atomic) + %lu (composite) collectable bytes in use\n",
 724                 (unsigned long)WORDS_TO_BYTES(GC_atomic_in_use),
 725                 (unsigned long)WORDS_TO_BYTES(GC_composite_in_use));
 726 #   endif
 727
 728       GC_n_attempts = 0;
 729       GC_is_full_gc = FALSE;
 730     /* Reset or increment counters for next cycle */
 731       GC_words_allocd_before_gc += GC_words_allocd;
 732       GC_non_gc_bytes_at_gc = GC_non_gc_bytes;
 733       GC_words_allocd = 0;
 734       GC_words_wasted = 0;
 735       GC_mem_freed = 0;
 736       GC_finalizer_mem_freed = 0;
 737
 738 #   ifdef USE_MUNMAP
 739       GC_unmap_old();
 740 #   endif
 741 #   ifdef PRINTTIMES
 742         GET_TIME(done_time);
 743         GC_printf2("Finalize + initiate sweep took %lu + %lu msecs\n",
 744                    MS_TIME_DIFF(finalize_time,start_time),
 745                    MS_TIME_DIFF(done_time,finalize_time));
 746 #   endif
 747 }
 748
 749 /* Externally callable routine to invoke full, stop-world collection */
 750 # if defined(__STDC__) || defined(__cplusplus)
 751     int GC_try_to_collect(GC_stop_func stop_func)
 752 # else
 753     int GC_try_to_collect(stop_func)
 754     GC_stop_func stop_func;
 755 # endif
 756 {
 757     int result;
 758     DCL_LOCK_STATE;
 759
 760     if (GC_debugging_started) GC_print_all_smashed();
 761     GC_INVOKE_FINALIZERS();
 762     DISABLE_SIGNALS();
 763     LOCK();
 764     ENTER_GC();
 765     if (!GC_is_initialized) GC_init_inner();
 766     /* Minimize junk left in my registers */
 767       GC_noop(0,0,0,0,0,0);
 768     result = (int)GC_try_to_collect_inner(stop_func);
 769     EXIT_GC();
 770     UNLOCK();
 771     ENABLE_SIGNALS();
 772     if(result) {
 773         if (GC_debugging_started) GC_print_all_smashed();
 774         GC_INVOKE_FINALIZERS();
 775     }
 776     return(result);
 777 }
 778
 779 void GC_gcollect GC_PROTO(())
 780 {
 781     (void)GC_try_to_collect(GC_never_stop_func);
 782     if (GC_have_errors) GC_print_all_errors();
 783 }
 784
 785 word GC_n_heap_sects = 0;       /* Number of sections currently in heap. */
 786
 787 /*
 788  * Use the chunk of memory starting at p of size bytes as part of the heap.
 789  * Assumes p is HBLKSIZE aligned, and bytes is a multiple of HBLKSIZE.
 790  */
 791 void GC_add_to_heap(p, bytes)
 792 struct hblk *p;
 793 word bytes;
 794 {
 795     word words;
 796     hdr * phdr;
 797
 798     if (GC_n_heap_sects >= MAX_HEAP_SECTS) {
 799         ABORT("Too many heap sections: Increase MAXHINCR or MAX_HEAP_SECTS");
 800     }
 801     phdr = GC_install_header(p);
 802     if (0 == phdr) {
 803         /* This is extremely unlikely. Can't add it.  This will         */
 804         /* almost certainly result in a 0 return from the allocator,    */
 805         /* which is entirely appropriate.                               */
 806         return;
 807     }
 808     GC_heap_sects[GC_n_heap_sects].hs_start = (ptr_t)p;
 809     GC_heap_sects[GC_n_heap_sects].hs_bytes = bytes;
 810     GC_n_heap_sects++;
 811     words = BYTES_TO_WORDS(bytes);
 812     phdr -> hb_sz = words;
 813     phdr -> hb_map = (unsigned char *)1;   /* A value != GC_invalid_map */
 814     phdr -> hb_flags = 0;
 815     GC_freehblk(p);
 816     GC_heapsize += bytes;
 817     if ((ptr_t)p <= (ptr_t)GC_least_plausible_heap_addr
 818         || GC_least_plausible_heap_addr == 0) {
 819         GC_least_plausible_heap_addr = (GC_PTR)((ptr_t)p - sizeof(word));
 820                 /* Making it a little smaller than necessary prevents   */
 821                 /* us from getting a false hit from the variable        */
 822                 /* itself.  There's some unintentional reflection       */
 823                 /* here.                                                */
 824     }
 825     if ((ptr_t)p + bytes >= (ptr_t)GC_greatest_plausible_heap_addr) {
 826         GC_greatest_plausible_heap_addr = (GC_PTR)((ptr_t)p + bytes);
 827     }
 828 }
 829
 830 # if !defined(NO_DEBUGGING)
 831 void GC_print_heap_sects()
 832 {
 833     register unsigned i;
 834
 835     GC_printf1("Total heap size: %lu\n", (unsigned long) GC_heapsize);
 836     for (i = 0; i < GC_n_heap_sects; i++) {
 837         unsigned long start = (unsigned long) GC_heap_sects[i].hs_start;
 838         unsigned long len = (unsigned long) GC_heap_sects[i].hs_bytes;
 839         struct hblk *h;
 840         unsigned nbl = 0;
 841
 842         GC_printf3("Section %ld from 0x%lx to 0x%lx ", (unsigned long)i,
 843                    start, (unsigned long)(start + len));
 844         for (h = (struct hblk *)start; h < (struct hblk *)(start + len); h++) {
 845             if (GC_is_black_listed(h, HBLKSIZE)) nbl++;
 846         }
 847         GC_printf2("%lu/%lu blacklisted\n", (unsigned long)nbl,
 848                    (unsigned long)(len/HBLKSIZE));
 849     }
 850 }
 851 # endif
 852
 853 GC_PTR GC_least_plausible_heap_addr = (GC_PTR)ONES;
 854 GC_PTR GC_greatest_plausible_heap_addr = 0;
 855
 856 ptr_t GC_max(x,y)
 857 ptr_t x, y;
 858 {
 859     return(x > y? x : y);
 860 }
 861
 862 ptr_t GC_min(x,y)
 863 ptr_t x, y;
 864 {
 865     return(x < y? x : y);
 866 }
 867
 868 # if defined(__STDC__) || defined(__cplusplus)
 869     void GC_set_max_heap_size(GC_word n)
 870 # else
 871     void GC_set_max_heap_size(n)
 872     GC_word n;
 873 # endif
 874 {
 875     GC_max_heapsize = n;
 876 }
 877
 878 GC_word GC_max_retries = 0;
 879
 880 /*
 881  * this explicitly increases the size of the heap.  It is used
 882  * internally, but may also be invoked from GC_expand_hp by the user.
 883  * The argument is in units of HBLKSIZE.
 884  * Tiny values of n are rounded up.
 885  * Returns FALSE on failure.
 886  */
 887 GC_bool GC_expand_hp_inner(n)
 888 word n;
 889 {
 890     word bytes;
 891     struct hblk * space;
 892     word expansion_slop;        /* Number of bytes by which we expect the */
 893                                 /* heap to expand soon.                   */
 894
 895     if (n < MINHINCR) n = MINHINCR;
 896     bytes = n * HBLKSIZE;
 897     /* Make sure bytes is a multiple of GC_page_size */
 898       {
 899         word mask = GC_page_size - 1;
 900         bytes += mask;
 901         bytes &= ~mask;
 902       }
 903
 904     if (GC_max_heapsize != 0 && GC_heapsize + bytes > GC_max_heapsize) {
 905         /* Exceeded self-imposed limit */
 906         return(FALSE);
 907     }
 908     space = GET_MEM(bytes);
 909     if( space == 0 ) {
 910 #       ifdef CONDPRINT
 911           if (GC_print_stats) {
 912             GC_printf1("Failed to expand heap by %ld bytes\n",
 913                        (unsigned long)bytes);
 914           }
 915 #       endif
 916         return(FALSE);
 917     }
 918 #   ifdef CONDPRINT
 919       if (GC_print_stats) {
 920         GC_printf2("Increasing heap size by %lu after %lu allocated bytes\n",
 921                    (unsigned long)bytes,
 922                    (unsigned long)WORDS_TO_BYTES(GC_words_allocd));
 923 #       ifdef UNDEFINED
 924           GC_printf1("Root size = %lu\n", GC_root_size);
 925           GC_print_block_list(); GC_print_hblkfreelist();
 926           GC_printf0("\n");
 927 #       endif
 928       }
 929 #   endif
 930     expansion_slop = WORDS_TO_BYTES(min_words_allocd()) + 4*MAXHINCR*HBLKSIZE;
 931     if (GC_last_heap_addr == 0 && !((word)space & SIGNB)
 932         || GC_last_heap_addr != 0 && GC_last_heap_addr < (ptr_t)space) {
 933         /* Assume the heap is growing up */
 934         GC_greatest_plausible_heap_addr =
 935             (GC_PTR)GC_max((ptr_t)GC_greatest_plausible_heap_addr,
 936                            (ptr_t)space + bytes + expansion_slop);
 937     } else {
 938         /* Heap is growing down */
 939         GC_least_plausible_heap_addr =
 940             (GC_PTR)GC_min((ptr_t)GC_least_plausible_heap_addr,
 941                            (ptr_t)space - expansion_slop);
 942     }
 943 #   if defined(LARGE_CONFIG)
 944       if (((ptr_t)GC_greatest_plausible_heap_addr <= (ptr_t)space + bytes
 945            || (ptr_t)GC_least_plausible_heap_addr >= (ptr_t)space)
 946           && GC_heapsize > 0) {
 947         /* GC_add_to_heap will fix this, but ... */
 948         WARN("Too close to address space limit: blacklisting ineffective\n", 0);
 949       }
 950 #   endif
 951     GC_prev_heap_addr = GC_last_heap_addr;
 952     GC_last_heap_addr = (ptr_t)space;
 953     GC_add_to_heap(space, bytes);
 954     /* Force GC before we are likely to allocate past expansion_slop */
 955       GC_collect_at_heapsize =
 956           GC_heapsize + expansion_slop - 2*MAXHINCR*HBLKSIZE;
 957 #     if defined(LARGE_CONFIG)
 958         if (GC_collect_at_heapsize < GC_heapsize /* wrapped */)
 959           GC_collect_at_heapsize = (word)(-1);
 960 #     endif
 961     return(TRUE);
 962 }
 963
 964 /* Really returns a bool, but it's externally visible, so that's clumsy. */
 965 /* Arguments is in bytes.                                               */
 966 # if defined(__STDC__) || defined(__cplusplus)
 967   int GC_expand_hp(size_t bytes)
 968 # else
 969   int GC_expand_hp(bytes)
 970   size_t bytes;
 971 # endif
 972 {
 973     int result;
 974     DCL_LOCK_STATE;
 975
 976     DISABLE_SIGNALS();
 977     LOCK();
 978     if (!GC_is_initialized) GC_init_inner();
 979     result = (int)GC_expand_hp_inner(divHBLKSZ((word)bytes));
 980     if (result) GC_requested_heapsize += bytes;
 981     UNLOCK();
 982     ENABLE_SIGNALS();
 983     return(result);
 984 }
 985
 986 unsigned GC_fail_count = 0;
 987                         /* How many consecutive GC/expansion failures?  */
 988                         /* Reset by GC_allochblk.                       */
 989
 990 GC_bool GC_collect_or_expand(needed_blocks, ignore_off_page)
 991 word needed_blocks;
 992 GC_bool ignore_off_page;
 993 {
 994     if (!GC_incremental && !GC_dont_gc &&
 995         (GC_dont_expand && GC_words_allocd > 0 || GC_should_collect())) {
 996       GC_gcollect_inner();
 997     } else {
 998       word blocks_to_get = GC_heapsize/(HBLKSIZE*GC_free_space_divisor)
 999                            + needed_blocks;
1000
1001       if (blocks_to_get > MAXHINCR) {
1002           word slop;
1003
1004           if (ignore_off_page) {
1005               slop = 4;
1006           } else {
1007               slop = 2*divHBLKSZ(BL_LIMIT);
1008               if (slop > needed_blocks) slop = needed_blocks;
1009           }
1010           if (needed_blocks + slop > MAXHINCR) {
1011               blocks_to_get = needed_blocks + slop;
1012           } else {
1013               blocks_to_get = MAXHINCR;
1014           }
1015       }
1016       if (!GC_expand_hp_inner(blocks_to_get)
1017         && !GC_expand_hp_inner(needed_blocks)) {
1018         if (GC_fail_count++ < GC_max_retries) {
1019             WARN("Out of Memory!  Trying to continue ...\n", 0);
1020             GC_gcollect_inner();
1021         } else {
1022 #           if !defined(AMIGA) || !defined(GC_AMIGA_FASTALLOC)
1023               WARN("Out of Memory!  Returning NIL!\n", 0);
1024 #           endif
1025             return(FALSE);
1026         }
1027       } else {
1028 #         ifdef CONDPRINT
1029             if (GC_fail_count && GC_print_stats) {
1030               GC_printf0("Memory available again ...\n");
1031             }
1032 #         endif
1033       }
1034     }
1035     return(TRUE);
1036 }
1037
1038 /*
1039  * Make sure the object free list for sz is not empty.
1040  * Return a pointer to the first object on the free list.
1041  * The object MUST BE REMOVED FROM THE FREE LIST BY THE CALLER.
1042  * Assumes we hold the allocator lock and signals are disabled.
1043  *
1044  */
1045 ptr_t GC_allocobj(sz, kind)
1046 word sz;
1047 int kind;
1048 {
1049     ptr_t * flh = &(GC_obj_kinds[kind].ok_freelist[sz]);
1050     GC_bool tried_minor = FALSE;
1051
1052     if (sz == 0) return(0);
1053
1054     while (*flh == 0) {
1055       ENTER_GC();
1056       /* Do our share of marking work */
1057         if(TRUE_INCREMENTAL) GC_collect_a_little_inner(1);
1058       /* Sweep blocks for objects of this size */
1059         GC_continue_reclaim(sz, kind);
1060       EXIT_GC();
1061       if (*flh == 0) {
1062         GC_new_hblk(sz, kind);
1063       }
1064       if (*flh == 0) {
1065         ENTER_GC();
1066         if (GC_incremental && GC_time_limit == GC_TIME_UNLIMITED
1067             && ! tried_minor ) {
1068             GC_collect_a_little_inner(1);
1069             tried_minor = TRUE;
1070         } else {
1071           if (!GC_collect_or_expand((word)1,FALSE)) {
1072             EXIT_GC();
1073             return(0);
1074           }
1075         }
1076         EXIT_GC();
1077       }
1078     }
1079     /* Successful allocation; reset failure count.      */
1080     GC_fail_count = 0;
1081
1082     return(*flh);
1083 }