boehm-gc/finalize.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) 1996-1999 by Silicon Graphics.  All rights reserved.
   5
   6  * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
   7  * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
   8  *
   9  * Permission is hereby granted to use or copy this program
  10  * for any purpose,  provided the above notices are retained on all copies.
  11  * Permission to modify the code and to distribute modified code is granted,
  12  * provided the above notices are retained, and a notice that the code was
  13  * modified is included with the above copyright notice.
  14  */
  15 /* Boehm, February 1, 1996 1:19 pm PST */
  16 # define I_HIDE_POINTERS
  17 # include "gc_priv.h"
  18 # include "gc_mark.h"
  19
  20 # ifdef FINALIZE_ON_DEMAND
  21     int GC_finalize_on_demand = 1;
  22 # else
  23     int GC_finalize_on_demand = 0;
  24 # endif
  25
  26 # ifdef JAVA_FINALIZATION
  27     int GC_java_finalization = 1;
  28 # else
  29     int GC_java_finalization = 0;
  30 # endif
  31
  32 /* Type of mark procedure used for marking from finalizable object.     */
  33 /* This procedure normally does not mark the object, only its           */
  34 /* descendents.                                                         */
  35 typedef void finalization_mark_proc(/* ptr_t finalizable_obj_ptr */);
  36
  37 # define HASH3(addr,size,log_size) \
  38     ((((word)(addr) >> 3) ^ ((word)(addr) >> (3+(log_size)))) \
  39     & ((size) - 1))
  40 #define HASH2(addr,log_size) HASH3(addr, 1 << log_size, log_size)
  41
  42 struct hash_chain_entry {
  43     word hidden_key;
  44     struct hash_chain_entry * next;
  45 };
  46
  47 unsigned GC_finalization_failures = 0;
  48         /* Number of finalization requests that failed for lack of memory. */
  49
  50 static struct disappearing_link {
  51     struct hash_chain_entry prolog;
  52 #   define dl_hidden_link prolog.hidden_key
  53                                 /* Field to be cleared.         */
  54 #   define dl_next(x) (struct disappearing_link *)((x) -> prolog.next)
  55 #   define dl_set_next(x,y) (x) -> prolog.next = (struct hash_chain_entry *)(y)
  56
  57     word dl_hidden_obj;         /* Pointer to object base       */
  58 } **dl_head = 0;
  59
  60 static signed_word log_dl_table_size = -1;
  61                         /* Binary log of                                */
  62                         /* current size of array pointed to by dl_head. */
  63                         /* -1 ==> size is 0.                            */
  64
  65 word GC_dl_entries = 0; /* Number of entries currently in disappearing  */
  66                         /* link table.                                  */
  67
  68 static struct finalizable_object {
  69     struct hash_chain_entry prolog;
  70 #   define fo_hidden_base prolog.hidden_key
  71                                 /* Pointer to object base.      */
  72                                 /* No longer hidden once object */
  73                                 /* is on finalize_now queue.    */
  74 #   define fo_next(x) (struct finalizable_object *)((x) -> prolog.next)
  75 #   define fo_set_next(x,y) (x) -> prolog.next = (struct hash_chain_entry *)(y)
  76     GC_finalization_proc fo_fn; /* Finalizer.                   */
  77     ptr_t fo_client_data;
  78     word fo_object_size;        /* In bytes.                    */
  79     finalization_mark_proc * fo_mark_proc;      /* Mark-through procedure */
  80 } **fo_head = 0;
  81
  82 struct finalizable_object * GC_finalize_now = 0;
  83         /* LIst of objects that should be finalized now.        */
  84
  85 static signed_word log_fo_table_size = -1;
  86
  87 word GC_fo_entries = 0;
  88
  89 # ifdef SRC_M3
  90 void GC_push_finalizer_structures()
  91 {
  92     GC_push_all((ptr_t)(&dl_head), (ptr_t)(&dl_head) + sizeof(word));
  93     GC_push_all((ptr_t)(&fo_head), (ptr_t)(&fo_head) + sizeof(word));
  94 }
  95 # endif
  96
  97 /* Double the size of a hash table. *size_ptr is the log of its current */
  98 /* size.  May be a noop.                                                */
  99 /* *table is a pointer to an array of hash headers.  If we succeed, we  */
 100 /* update both *table and *log_size_ptr.                                */
 101 /* Lock is held.  Signals are disabled.                                 */
 102 void GC_grow_table(table, log_size_ptr)
 103 struct hash_chain_entry ***table;
 104 signed_word * log_size_ptr;
 105 {
 106     register word i;
 107     register struct hash_chain_entry *p;
 108     int log_old_size = *log_size_ptr;
 109     register int log_new_size = log_old_size + 1;
 110     word old_size = ((log_old_size == -1)? 0: (1 << log_old_size));
 111     register word new_size = 1 << log_new_size;
 112     struct hash_chain_entry **new_table = (struct hash_chain_entry **)
 113         GC_generic_malloc_inner_ignore_off_page(
 114                 (size_t)new_size * sizeof(struct hash_chain_entry *), NORMAL);
 115
 116     if (new_table == 0) {
 117         if (table == 0) {
 118             ABORT("Insufficient space for initial table allocation");
 119         } else {
 120             return;
 121         }
 122     }
 123     for (i = 0; i < old_size; i++) {
 124       p = (*table)[i];
 125       while (p != 0) {
 126         register ptr_t real_key = (ptr_t)REVEAL_POINTER(p -> hidden_key);
 127         register struct hash_chain_entry *next = p -> next;
 128         register int new_hash = HASH3(real_key, new_size, log_new_size);
 129
 130         p -> next = new_table[new_hash];
 131         new_table[new_hash] = p;
 132         p = next;
 133       }
 134     }
 135     *log_size_ptr = log_new_size;
 136     *table = new_table;
 137 }
 138
 139 # if defined(__STDC__) || defined(__cplusplus)
 140     int GC_register_disappearing_link(GC_PTR * link)
 141 # else
 142     int GC_register_disappearing_link(link)
 143     GC_PTR * link;
 144 # endif
 145 {
 146     ptr_t base;
 147
 148     base = (ptr_t)GC_base((GC_PTR)link);
 149     if (base == 0)
 150         ABORT("Bad arg to GC_register_disappearing_link");
 151     return(GC_general_register_disappearing_link(link, base));
 152 }
 153
 154 # if defined(__STDC__) || defined(__cplusplus)
 155     int GC_general_register_disappearing_link(GC_PTR * link,
 156                                               GC_PTR obj)
 157 # else
 158     int GC_general_register_disappearing_link(link, obj)
 159     GC_PTR * link;
 160     GC_PTR obj;
 161 # endif
 162
 163 {
 164     struct disappearing_link *curr_dl;
 165     int index;
 166     struct disappearing_link * new_dl;
 167     DCL_LOCK_STATE;
 168
 169     if ((word)link & (ALIGNMENT-1))
 170         ABORT("Bad arg to GC_general_register_disappearing_link");
 171 #   ifdef THREADS
 172         DISABLE_SIGNALS();
 173         LOCK();
 174 #   endif
 175     if (log_dl_table_size == -1
 176         || GC_dl_entries > ((word)1 << log_dl_table_size)) {
 177 #       ifndef THREADS
 178             DISABLE_SIGNALS();
 179 #       endif
 180         GC_grow_table((struct hash_chain_entry ***)(&dl_head),
 181                       &log_dl_table_size);
 182 #       ifdef PRINTSTATS
 183             GC_printf1("Grew dl table to %lu entries\n",
 184                         (unsigned long)(1 << log_dl_table_size));
 185 #       endif
 186 #       ifndef THREADS
 187             ENABLE_SIGNALS();
 188 #       endif
 189     }
 190     index = HASH2(link, log_dl_table_size);
 191     curr_dl = dl_head[index];
 192     for (curr_dl = dl_head[index]; curr_dl != 0; curr_dl = dl_next(curr_dl)) {
 193         if (curr_dl -> dl_hidden_link == HIDE_POINTER(link)) {
 194             curr_dl -> dl_hidden_obj = HIDE_POINTER(obj);
 195 #           ifdef THREADS
 196                 UNLOCK();
 197                 ENABLE_SIGNALS();
 198 #           endif
 199             return(1);
 200         }
 201     }
 202 #   ifdef THREADS
 203       new_dl = (struct disappearing_link *)
 204         GC_generic_malloc_inner(sizeof(struct disappearing_link),NORMAL);
 205 #   else
 206       new_dl = (struct disappearing_link *)
 207         GC_malloc(sizeof(struct disappearing_link));
 208 #   endif
 209     if (new_dl != 0) {
 210         new_dl -> dl_hidden_obj = HIDE_POINTER(obj);
 211         new_dl -> dl_hidden_link = HIDE_POINTER(link);
 212         dl_set_next(new_dl, dl_head[index]);
 213         dl_head[index] = new_dl;
 214         GC_dl_entries++;
 215     } else {
 216         GC_finalization_failures++;
 217     }
 218 #   ifdef THREADS
 219         UNLOCK();
 220         ENABLE_SIGNALS();
 221 #   endif
 222     return(0);
 223 }
 224
 225 # if defined(__STDC__) || defined(__cplusplus)
 226     int GC_unregister_disappearing_link(GC_PTR * link)
 227 # else
 228     int GC_unregister_disappearing_link(link)
 229     GC_PTR * link;
 230 # endif
 231 {
 232     struct disappearing_link *curr_dl, *prev_dl;
 233     int index;
 234     DCL_LOCK_STATE;
 235
 236     DISABLE_SIGNALS();
 237     LOCK();
 238     index = HASH2(link, log_dl_table_size);
 239     if (((unsigned long)link & (ALIGNMENT-1))) goto out;
 240     prev_dl = 0; curr_dl = dl_head[index];
 241     while (curr_dl != 0) {
 242         if (curr_dl -> dl_hidden_link == HIDE_POINTER(link)) {
 243             if (prev_dl == 0) {
 244                 dl_head[index] = dl_next(curr_dl);
 245             } else {
 246                 dl_set_next(prev_dl, dl_next(curr_dl));
 247             }
 248             GC_dl_entries--;
 249             UNLOCK();
 250             ENABLE_SIGNALS();
 251             GC_free((GC_PTR)curr_dl);
 252             return(1);
 253         }
 254         prev_dl = curr_dl;
 255         curr_dl = dl_next(curr_dl);
 256     }
 257 out:
 258     UNLOCK();
 259     ENABLE_SIGNALS();
 260     return(0);
 261 }
 262
 263 /* Possible finalization_marker procedures.  Note that mark stack       */
 264 /* overflow is handled by the caller, and is not a disaster.            */
 265 GC_API void GC_normal_finalize_mark_proc(p)
 266 ptr_t p;
 267 {
 268     hdr * hhdr = HDR(p);
 269
 270     PUSH_OBJ((word *)p, hhdr, GC_mark_stack_top,
 271              &(GC_mark_stack[GC_mark_stack_size]));
 272 }
 273
 274 /* This only pays very partial attention to the mark descriptor.        */
 275 /* It does the right thing for normal and atomic objects, and treats    */
 276 /* most others as normal.                                               */
 277 GC_API void GC_ignore_self_finalize_mark_proc(p)
 278 ptr_t p;
 279 {
 280     hdr * hhdr = HDR(p);
 281     word descr = hhdr -> hb_descr;
 282     ptr_t q, r;
 283     ptr_t scan_limit;
 284     ptr_t target_limit = p + WORDS_TO_BYTES(hhdr -> hb_sz) - 1;
 285
 286     if ((descr & DS_TAGS) == DS_LENGTH) {
 287        scan_limit = p + descr - sizeof(word);
 288     } else {
 289        scan_limit = target_limit + 1 - sizeof(word);
 290     }
 291     for (q = p; q <= scan_limit; q += ALIGNMENT) {
 292         r = *(ptr_t *)q;
 293         if (r < p || r > target_limit) {
 294             GC_PUSH_ONE_HEAP((word)r, q);
 295         }
 296     }
 297 }
 298
 299 /*ARGSUSED*/
 300 GC_API void GC_null_finalize_mark_proc(p)
 301 ptr_t p;
 302 {
 303 }
 304
 305
 306
 307 /* Register a finalization function.  See gc.h for details.     */
 308 /* in the nonthreads case, we try to avoid disabling signals,   */
 309 /* since it can be expensive.  Threads packages typically       */
 310 /* make it cheaper.                                             */
 311 /* The last parameter is a procedure that determines            */
 312 /* marking for finalization ordering.  Any objects marked       */
 313 /* by that procedure will be guaranteed to not have been        */
 314 /* finalized when this finalizer is invoked.                    */
 315 GC_API void GC_register_finalizer_inner(obj, fn, cd, ofn, ocd, mp)
 316 GC_PTR obj;
 317 GC_finalization_proc fn;
 318 GC_PTR cd;
 319 GC_finalization_proc * ofn;
 320 GC_PTR * ocd;
 321 finalization_mark_proc * mp;
 322 {
 323     ptr_t base;
 324     struct finalizable_object * curr_fo, * prev_fo;
 325     int index;
 326     struct finalizable_object *new_fo;
 327     DCL_LOCK_STATE;
 328
 329 #   ifdef THREADS
 330         DISABLE_SIGNALS();
 331         LOCK();
 332 #   endif
 333     if (log_fo_table_size == -1
 334         || GC_fo_entries > ((word)1 << log_fo_table_size)) {
 335 #       ifndef THREADS
 336             DISABLE_SIGNALS();
 337 #       endif
 338         GC_grow_table((struct hash_chain_entry ***)(&fo_head),
 339                       &log_fo_table_size);
 340 #       ifdef PRINTSTATS
 341             GC_printf1("Grew fo table to %lu entries\n",
 342                         (unsigned long)(1 << log_fo_table_size));
 343 #       endif
 344 #       ifndef THREADS
 345             ENABLE_SIGNALS();
 346 #       endif
 347     }
 348     /* in the THREADS case signals are disabled and we hold allocation  */
 349     /* lock; otherwise neither is true.  Proceed carefully.             */
 350     base = (ptr_t)obj;
 351     index = HASH2(base, log_fo_table_size);
 352     prev_fo = 0; curr_fo = fo_head[index];
 353     while (curr_fo != 0) {
 354         if (curr_fo -> fo_hidden_base == HIDE_POINTER(base)) {
 355             /* Interruption by a signal in the middle of this   */
 356             /* should be safe.  The client may see only *ocd    */
 357             /* updated, but we'll declare that to be his        */
 358             /* problem.                                         */
 359             if (ocd) *ocd = (GC_PTR) curr_fo -> fo_client_data;
 360             if (ofn) *ofn = curr_fo -> fo_fn;
 361             /* Delete the structure for base. */
 362                 if (prev_fo == 0) {
 363                   fo_head[index] = fo_next(curr_fo);
 364                 } else {
 365                   fo_set_next(prev_fo, fo_next(curr_fo));
 366                 }
 367             if (fn == 0) {
 368                 GC_fo_entries--;
 369                   /* May not happen if we get a signal.  But a high     */
 370                   /* estimate will only make the table larger than      */
 371                   /* necessary.                                         */
 372 #               ifndef THREADS
 373                   GC_free((GC_PTR)curr_fo);
 374 #               endif
 375             } else {
 376                 curr_fo -> fo_fn = fn;
 377                 curr_fo -> fo_client_data = (ptr_t)cd;
 378                 curr_fo -> fo_mark_proc = mp;
 379                 /* Reinsert it.  We deleted it first to maintain        */
 380                 /* consistency in the event of a signal.                */
 381                 if (prev_fo == 0) {
 382                   fo_head[index] = curr_fo;
 383                 } else {
 384                   fo_set_next(prev_fo, curr_fo);
 385                 }
 386             }
 387 #           ifdef THREADS
 388                 UNLOCK();
 389                 ENABLE_SIGNALS();
 390 #           endif
 391             return;
 392         }
 393         prev_fo = curr_fo;
 394         curr_fo = fo_next(curr_fo);
 395     }
 396     if (ofn) *ofn = 0;
 397     if (ocd) *ocd = 0;
 398     if (fn == 0) {
 399 #       ifdef THREADS
 400             UNLOCK();
 401             ENABLE_SIGNALS();
 402 #       endif
 403         return;
 404     }
 405 #   ifdef THREADS
 406       new_fo = (struct finalizable_object *)
 407         GC_generic_malloc_inner(sizeof(struct finalizable_object),NORMAL);
 408 #   else
 409       new_fo = (struct finalizable_object *)
 410         GC_malloc(sizeof(struct finalizable_object));
 411 #   endif
 412     if (new_fo != 0) {
 413         new_fo -> fo_hidden_base = (word)HIDE_POINTER(base);
 414         new_fo -> fo_fn = fn;
 415         new_fo -> fo_client_data = (ptr_t)cd;
 416         new_fo -> fo_object_size = GC_size(base);
 417         new_fo -> fo_mark_proc = mp;
 418         fo_set_next(new_fo, fo_head[index]);
 419         GC_fo_entries++;
 420         fo_head[index] = new_fo;
 421     } else {
 422         GC_finalization_failures++;
 423     }
 424 #   ifdef THREADS
 425         UNLOCK();
 426         ENABLE_SIGNALS();
 427 #   endif
 428 }
 429
 430 # if defined(__STDC__)
 431     void GC_register_finalizer(void * obj,
 432                                GC_finalization_proc fn, void * cd,
 433                                GC_finalization_proc *ofn, void ** ocd)
 434 # else
 435     void GC_register_finalizer(obj, fn, cd, ofn, ocd)
 436     GC_PTR obj;
 437     GC_finalization_proc fn;
 438     GC_PTR cd;
 439     GC_finalization_proc * ofn;
 440     GC_PTR * ocd;
 441 # endif
 442 {
 443     GC_register_finalizer_inner(obj, fn, cd, ofn,
 444                                 ocd, GC_normal_finalize_mark_proc);
 445 }
 446
 447 # if defined(__STDC__)
 448     void GC_register_finalizer_ignore_self(void * obj,
 449                                GC_finalization_proc fn, void * cd,
 450                                GC_finalization_proc *ofn, void ** ocd)
 451 # else
 452     void GC_register_finalizer_ignore_self(obj, fn, cd, ofn, ocd)
 453     GC_PTR obj;
 454     GC_finalization_proc fn;
 455     GC_PTR cd;
 456     GC_finalization_proc * ofn;
 457     GC_PTR * ocd;
 458 # endif
 459 {
 460     GC_register_finalizer_inner(obj, fn, cd, ofn,
 461                                 ocd, GC_ignore_self_finalize_mark_proc);
 462 }
 463
 464 # if defined(__STDC__)
 465     void GC_register_finalizer_no_order(void * obj,
 466                                GC_finalization_proc fn, void * cd,
 467                                GC_finalization_proc *ofn, void ** ocd)
 468 # else
 469     void GC_register_finalizer_no_order(obj, fn, cd, ofn, ocd)
 470     GC_PTR obj;
 471     GC_finalization_proc fn;
 472     GC_PTR cd;
 473     GC_finalization_proc * ofn;
 474     GC_PTR * ocd;
 475 # endif
 476 {
 477     GC_register_finalizer_inner(obj, fn, cd, ofn,
 478                                 ocd, GC_null_finalize_mark_proc);
 479 }
 480
 481 /* Called with world stopped.  Cause disappearing links to disappear,   */
 482 /* and invoke finalizers.                                               */
 483 void GC_finalize()
 484 {
 485     struct disappearing_link * curr_dl, * prev_dl, * next_dl;
 486     struct finalizable_object * curr_fo, * prev_fo, * next_fo;
 487     ptr_t real_ptr, real_link;
 488     register int i;
 489     int dl_size = (log_dl_table_size == -1 ) ? 0 : (1 << log_dl_table_size);
 490     int fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);
 491
 492   /* Make disappearing links disappear */
 493     for (i = 0; i < dl_size; i++) {
 494       curr_dl = dl_head[i];
 495       prev_dl = 0;
 496       while (curr_dl != 0) {
 497         real_ptr = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_obj);
 498         real_link = (ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link);
 499         if (!GC_is_marked(real_ptr)) {
 500             *(word *)real_link = 0;
 501             next_dl = dl_next(curr_dl);
 502             if (prev_dl == 0) {
 503                 dl_head[i] = next_dl;
 504             } else {
 505                 dl_set_next(prev_dl, next_dl);
 506             }
 507             GC_clear_mark_bit((ptr_t)curr_dl);
 508             GC_dl_entries--;
 509             curr_dl = next_dl;
 510         } else {
 511             prev_dl = curr_dl;
 512             curr_dl = dl_next(curr_dl);
 513         }
 514       }
 515     }
 516   /* Mark all objects reachable via chains of 1 or more pointers        */
 517   /* from finalizable objects.                                          */
 518 #   ifdef PRINTSTATS
 519         if (GC_mark_state != MS_NONE) ABORT("Bad mark state");
 520 #   endif
 521     for (i = 0; i < fo_size; i++) {
 522       for (curr_fo = fo_head[i]; curr_fo != 0; curr_fo = fo_next(curr_fo)) {
 523         real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 524         if (!GC_is_marked(real_ptr)) {
 525             GC_MARKED_FOR_FINALIZATION(real_ptr);
 526             GC_MARK_FO(real_ptr, curr_fo -> fo_mark_proc);
 527             if (GC_is_marked(real_ptr)) {
 528                 WARN("Finalization cycle involving %lx\n", real_ptr);
 529             }
 530         }
 531       }
 532     }
 533   /* Enqueue for finalization all objects that are still                */
 534   /* unreachable.                                                       */
 535     GC_words_finalized = 0;
 536     for (i = 0; i < fo_size; i++) {
 537       curr_fo = fo_head[i];
 538       prev_fo = 0;
 539       while (curr_fo != 0) {
 540         real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 541         if (!GC_is_marked(real_ptr)) {
 542             if (!GC_java_finalization) {
 543               GC_set_mark_bit(real_ptr);
 544             }
 545             /* Delete from hash table */
 546               next_fo = fo_next(curr_fo);
 547               if (prev_fo == 0) {
 548                 fo_head[i] = next_fo;
 549               } else {
 550                 fo_set_next(prev_fo, next_fo);
 551               }
 552               GC_fo_entries--;
 553             /* Add to list of objects awaiting finalization.    */
 554               fo_set_next(curr_fo, GC_finalize_now);
 555               GC_finalize_now = curr_fo;
 556               /* unhide object pointer so any future collections will   */
 557               /* see it.                                                */
 558               curr_fo -> fo_hidden_base =
 559                         (word) REVEAL_POINTER(curr_fo -> fo_hidden_base);
 560               GC_words_finalized +=
 561                         ALIGNED_WORDS(curr_fo -> fo_object_size)
 562                         + ALIGNED_WORDS(sizeof(struct finalizable_object));
 563 #           ifdef PRINTSTATS
 564               if (!GC_is_marked((ptr_t)curr_fo)) {
 565                 ABORT("GC_finalize: found accessible unmarked object\n");
 566               }
 567 #           endif
 568             curr_fo = next_fo;
 569         } else {
 570             prev_fo = curr_fo;
 571             curr_fo = fo_next(curr_fo);
 572         }
 573       }
 574     }
 575
 576   if (GC_java_finalization) {
 577     /* make sure we mark everything reachable from objects finalized
 578        using the no_order mark_proc */
 579       for (curr_fo = GC_finalize_now;
 580          curr_fo != NULL; curr_fo = fo_next(curr_fo)) {
 581         real_ptr = (ptr_t)curr_fo -> fo_hidden_base;
 582         if (!GC_is_marked(real_ptr)) {
 583             if (curr_fo -> fo_mark_proc == GC_null_finalize_mark_proc) {
 584                 GC_MARK_FO(real_ptr, GC_normal_finalize_mark_proc);
 585             }
 586             GC_set_mark_bit(real_ptr);
 587         }
 588       }
 589   }
 590
 591   /* Remove dangling disappearing links. */
 592     for (i = 0; i < dl_size; i++) {
 593       curr_dl = dl_head[i];
 594       prev_dl = 0;
 595       while (curr_dl != 0) {
 596         real_link = GC_base((ptr_t)REVEAL_POINTER(curr_dl -> dl_hidden_link));
 597         if (real_link != 0 && !GC_is_marked(real_link)) {
 598             next_dl = dl_next(curr_dl);
 599             if (prev_dl == 0) {
 600                 dl_head[i] = next_dl;
 601             } else {
 602                 dl_set_next(prev_dl, next_dl);
 603             }
 604             GC_clear_mark_bit((ptr_t)curr_dl);
 605             GC_dl_entries--;
 606             curr_dl = next_dl;
 607         } else {
 608             prev_dl = curr_dl;
 609             curr_dl = dl_next(curr_dl);
 610         }
 611       }
 612     }
 613 }
 614
 615 #ifndef JAVA_FINALIZATION_NOT_NEEDED
 616
 617 /* Enqueue all remaining finalizers to be run - Assumes lock is
 618  * held, and signals are disabled */
 619 void GC_enqueue_all_finalizers()
 620 {
 621     struct finalizable_object * curr_fo, * prev_fo, * next_fo;
 622     ptr_t real_ptr;
 623     register int i;
 624     int fo_size;
 625
 626     fo_size = (log_fo_table_size == -1 ) ? 0 : (1 << log_fo_table_size);
 627     GC_words_finalized = 0;
 628     for (i = 0; i < fo_size; i++) {
 629         curr_fo = fo_head[i];
 630         prev_fo = 0;
 631       while (curr_fo != 0) {
 632           real_ptr = (ptr_t)REVEAL_POINTER(curr_fo -> fo_hidden_base);
 633           GC_MARK_FO(real_ptr, GC_normal_finalize_mark_proc);
 634           GC_set_mark_bit(real_ptr);
 635
 636           /* Delete from hash table */
 637           next_fo = fo_next(curr_fo);
 638           if (prev_fo == 0) {
 639               fo_head[i] = next_fo;
 640           } else {
 641               fo_set_next(prev_fo, next_fo);
 642           }
 643           GC_fo_entries--;
 644
 645           /* Add to list of objects awaiting finalization.      */
 646           fo_set_next(curr_fo, GC_finalize_now);
 647           GC_finalize_now = curr_fo;
 648
 649           /* unhide object pointer so any future collections will       */
 650           /* see it.                                            */
 651           curr_fo -> fo_hidden_base =
 652                         (word) REVEAL_POINTER(curr_fo -> fo_hidden_base);
 653
 654           GC_words_finalized +=
 655                 ALIGNED_WORDS(curr_fo -> fo_object_size)
 656                         + ALIGNED_WORDS(sizeof(struct finalizable_object));
 657           curr_fo = next_fo;
 658         }
 659     }
 660
 661     return;
 662 }
 663
 664 /* Invoke all remaining finalizers that haven't yet been run.
 665  * This is needed for strict compliance with the Java standard,
 666  * which can make the runtime guarantee that all finalizers are run.
 667  * Unfortunately, the Java standard implies we have to keep running
 668  * finalizers until there are no more left, a potential infinite loop.
 669  * YUCK.
 670  * Note that this is even more dangerous than the usual Java
 671  * finalizers, in that objects reachable from static variables
 672  * may have been finalized when these finalizers are run.
 673  * Finalizers run at this point must be prepared to deal with a
 674  * mostly broken world.
 675  * This routine is externally callable, so is called without
 676  * the allocation lock.
 677  */
 678 GC_API void GC_finalize_all()
 679 {
 680     DCL_LOCK_STATE;
 681
 682     DISABLE_SIGNALS();
 683     LOCK();
 684     while (GC_fo_entries > 0) {
 685       GC_enqueue_all_finalizers();
 686       UNLOCK();
 687       ENABLE_SIGNALS();
 688       GC_INVOKE_FINALIZERS();
 689       DISABLE_SIGNALS();
 690       LOCK();
 691     }
 692     UNLOCK();
 693     ENABLE_SIGNALS();
 694 }
 695 #endif
 696
 697 /* Returns true if it is worth calling GC_invoke_finalizers. (Useful if */
 698 /* finalizers can only be called from some kind of `safe state' and     */
 699 /* getting into that safe state is expensive.)                          */
 700 int GC_should_invoke_finalizers GC_PROTO((void))
 701 {
 702     return GC_finalize_now != 0;
 703 }
 704
 705 /* Invoke finalizers for all objects that are ready to be finalized.    */
 706 /* Should be called without allocation lock.                            */
 707 int GC_invoke_finalizers()
 708 {
 709     register struct finalizable_object * curr_fo;
 710     register int count = 0;
 711     DCL_LOCK_STATE;
 712
 713     while (GC_finalize_now != 0) {
 714 #       ifdef THREADS
 715             DISABLE_SIGNALS();
 716             LOCK();
 717 #       endif
 718         curr_fo = GC_finalize_now;
 719 #       ifdef THREADS
 720             if (curr_fo != 0) GC_finalize_now = fo_next(curr_fo);
 721             UNLOCK();
 722             ENABLE_SIGNALS();
 723             if (curr_fo == 0) break;
 724 #       else
 725             GC_finalize_now = fo_next(curr_fo);
 726 #       endif
 727         fo_set_next(curr_fo, 0);
 728         (*(curr_fo -> fo_fn))((ptr_t)(curr_fo -> fo_hidden_base),
 729                               curr_fo -> fo_client_data);
 730         curr_fo -> fo_client_data = 0;
 731         ++count;
 732 #       ifdef UNDEFINED
 733             /* This is probably a bad idea.  It throws off accounting if */
 734             /* nearly all objects are finalizable.  O.w. it shouldn't    */
 735             /* matter.                                                   */
 736             GC_free((GC_PTR)curr_fo);
 737 #       endif
 738     }
 739     return count;
 740 }
 741
 742 # ifdef __STDC__
 743     GC_PTR GC_call_with_alloc_lock(GC_fn_type fn,
 744                                          GC_PTR client_data)
 745 # else
 746     GC_PTR GC_call_with_alloc_lock(fn, client_data)
 747     GC_fn_type fn;
 748     GC_PTR client_data;
 749 # endif
 750 {
 751     GC_PTR result;
 752     DCL_LOCK_STATE;
 753
 754 #   ifdef THREADS
 755       DISABLE_SIGNALS();
 756       LOCK();
 757       SET_LOCK_HOLDER();
 758 #   endif
 759     result = (*fn)(client_data);
 760 #   ifdef THREADS
 761       UNSET_LOCK_HOLDER();
 762       UNLOCK();
 763       ENABLE_SIGNALS();
 764 #   endif
 765     return(result);
 766 }