boehm-gc/mallocx.c

   1 /*
   2  * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
   3  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
   4  * Copyright (c) 1996 by Silicon Graphics.  All rights reserved.
   5  * Copyright (c) 2000 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  * These are extra allocation routines which are likely to be less
  19  * frequently used than those in malloc.c.  They are separate in the
  20  * hope that the .o file will be excluded from statically linked
  21  * executables.  We should probably break this up further.
  22  */
  23
  24 #include <stdio.h>
  25 #include "private/gc_priv.h"
  26
  27 extern ptr_t GC_clear_stack();  /* in misc.c, behaves like identity */
  28 void GC_extend_size_map();      /* in misc.c. */
  29 GC_bool GC_alloc_reclaim_list();        /* in malloc.c */
  30
  31 /* Some externally visible but unadvertised variables to allow access to */
  32 /* free lists from inlined allocators without including gc_priv.h        */
  33 /* or introducing dependencies on internal data structure layouts.       */
  34 ptr_t * GC_CONST GC_objfreelist_ptr = GC_objfreelist;
  35 ptr_t * GC_CONST GC_aobjfreelist_ptr = GC_aobjfreelist;
  36 ptr_t * GC_CONST GC_uobjfreelist_ptr = GC_uobjfreelist;
  37 # ifdef ATOMIC_UNCOLLECTABLE
  38     ptr_t * GC_CONST GC_auobjfreelist_ptr = GC_auobjfreelist;
  39 # endif
  40
  41
  42 GC_PTR GC_generic_or_special_malloc(lb,knd)
  43 word lb;
  44 int knd;
  45 {
  46     switch(knd) {
  47 #     ifdef STUBBORN_ALLOC
  48         case STUBBORN:
  49             return(GC_malloc_stubborn((size_t)lb));
  50 #     endif
  51         case PTRFREE:
  52             return(GC_malloc_atomic((size_t)lb));
  53         case NORMAL:
  54             return(GC_malloc((size_t)lb));
  55         case UNCOLLECTABLE:
  56             return(GC_malloc_uncollectable((size_t)lb));
  57 #       ifdef ATOMIC_UNCOLLECTABLE
  58           case AUNCOLLECTABLE:
  59             return(GC_malloc_atomic_uncollectable((size_t)lb));
  60 #       endif /* ATOMIC_UNCOLLECTABLE */
  61         default:
  62             return(GC_generic_malloc(lb,knd));
  63     }
  64 }
  65
  66
  67 /* Change the size of the block pointed to by p to contain at least   */
  68 /* lb bytes.  The object may be (and quite likely will be) moved.     */
  69 /* The kind (e.g. atomic) is the same as that of the old.             */
  70 /* Shrinking of large blocks is not implemented well.                 */
  71 # ifdef __STDC__
  72     GC_PTR GC_realloc(GC_PTR p, size_t lb)
  73 # else
  74     GC_PTR GC_realloc(p,lb)
  75     GC_PTR p;
  76     size_t lb;
  77 # endif
  78 {
  79 register struct hblk * h;
  80 register hdr * hhdr;
  81 register word sz;        /* Current size in bytes       */
  82 register word orig_sz;   /* Original sz in bytes        */
  83 int obj_kind;
  84
  85     if (p == 0) return(GC_malloc(lb));  /* Required by ANSI */
  86     h = HBLKPTR(p);
  87     hhdr = HDR(h);
  88     sz = hhdr -> hb_sz;
  89     obj_kind = hhdr -> hb_obj_kind;
  90     sz = WORDS_TO_BYTES(sz);
  91     orig_sz = sz;
  92
  93     if (sz > MAXOBJBYTES) {
  94         /* Round it up to the next whole heap block */
  95           register word descr;
  96
  97           sz = (sz+HBLKSIZE-1) & (~HBLKMASK);
  98           hhdr -> hb_sz = BYTES_TO_WORDS(sz);
  99           descr = GC_obj_kinds[obj_kind].ok_descriptor;
 100           if (GC_obj_kinds[obj_kind].ok_relocate_descr) descr += sz;
 101           hhdr -> hb_descr = descr;
 102           if (IS_UNCOLLECTABLE(obj_kind)) GC_non_gc_bytes += (sz - orig_sz);
 103           /* Extra area is already cleared by GC_alloc_large_and_clear. */
 104     }
 105     if (ADD_SLOP(lb) <= sz) {
 106         if (lb >= (sz >> 1)) {
 107 #           ifdef STUBBORN_ALLOC
 108                 if (obj_kind == STUBBORN) GC_change_stubborn(p);
 109 #           endif
 110             if (orig_sz > lb) {
 111               /* Clear unneeded part of object to avoid bogus pointer */
 112               /* tracing.                                             */
 113               /* Safe for stubborn objects.                           */
 114                 BZERO(((ptr_t)p) + lb, orig_sz - lb);
 115             }
 116             return(p);
 117         } else {
 118             /* shrink */
 119               GC_PTR result =
 120                         GC_generic_or_special_malloc((word)lb, obj_kind);
 121
 122               if (result == 0) return(0);
 123                   /* Could also return original object.  But this       */
 124                   /* gives the client warning of imminent disaster.     */
 125               BCOPY(p, result, lb);
 126 #             ifndef IGNORE_FREE
 127                 GC_free(p);
 128 #             endif
 129               return(result);
 130         }
 131     } else {
 132         /* grow */
 133           GC_PTR result =
 134                 GC_generic_or_special_malloc((word)lb, obj_kind);
 135
 136           if (result == 0) return(0);
 137           BCOPY(p, result, sz);
 138 #         ifndef IGNORE_FREE
 139             GC_free(p);
 140 #         endif
 141           return(result);
 142     }
 143 }
 144
 145 # if defined(REDIRECT_MALLOC) && !defined(REDIRECT_REALLOC)
 146 #   define REDIRECT_REALLOC GC_realloc
 147 # endif
 148
 149 # ifdef REDIRECT_REALLOC
 150
 151 /* As with malloc, avoid two levels of extra calls here.        */
 152 # ifdef GC_ADD_CALLER
 153 #   define RA GC_RETURN_ADDR,
 154 # else
 155 #   define RA
 156 # endif
 157 # define GC_debug_realloc_replacement(p, lb) \
 158         GC_debug_realloc(p, lb, RA "unknown", 0)
 159
 160 # ifdef __STDC__
 161     GC_PTR realloc(GC_PTR p, size_t lb)
 162 # else
 163     GC_PTR realloc(p,lb)
 164     GC_PTR p;
 165     size_t lb;
 166 # endif
 167   {
 168     return(REDIRECT_REALLOC(p, lb));
 169   }
 170
 171 # undef GC_debug_realloc_replacement
 172 # endif /* REDIRECT_REALLOC */
 173
 174
 175 /* The same thing, except caller does not hold allocation lock. */
 176 /* We avoid holding allocation lock while we clear memory.      */
 177 ptr_t GC_generic_malloc_ignore_off_page(lb, k)
 178 register size_t lb;
 179 register int k;
 180 {
 181     register ptr_t result;
 182     word lw;
 183     word n_blocks;
 184     GC_bool init;
 185     DCL_LOCK_STATE;
 186
 187     if (SMALL_OBJ(lb))
 188         return(GC_generic_malloc((word)lb, k));
 189     lw = ROUNDED_UP_WORDS(lb);
 190     n_blocks = OBJ_SZ_TO_BLOCKS(lw);
 191     init = GC_obj_kinds[k].ok_init;
 192     if (GC_have_errors) GC_print_all_errors();
 193     GC_INVOKE_FINALIZERS();
 194     DISABLE_SIGNALS();
 195     LOCK();
 196     result = (ptr_t)GC_alloc_large(lw, k, IGNORE_OFF_PAGE);
 197     if (0 != result) {
 198         if (GC_debugging_started) {
 199             BZERO(result, n_blocks * HBLKSIZE);
 200         } else {
 201 #           ifdef THREADS
 202               /* Clear any memory that might be used for GC descriptors */
 203               /* before we release the lock.                          */
 204                 ((word *)result)[0] = 0;
 205                 ((word *)result)[1] = 0;
 206                 ((word *)result)[lw-1] = 0;
 207                 ((word *)result)[lw-2] = 0;
 208 #           endif
 209         }
 210     }
 211     GC_words_allocd += lw;
 212     UNLOCK();
 213     ENABLE_SIGNALS();
 214     if (0 == result) {
 215         return((*GC_oom_fn)(lb));
 216     } else {
 217         if (init && !GC_debugging_started) {
 218             BZERO(result, n_blocks * HBLKSIZE);
 219         }
 220         return(result);
 221     }
 222 }
 223
 224 # if defined(__STDC__) || defined(__cplusplus)
 225   void * GC_malloc_ignore_off_page(size_t lb)
 226 # else
 227   char * GC_malloc_ignore_off_page(lb)
 228   register size_t lb;
 229 # endif
 230 {
 231     return((GC_PTR)GC_generic_malloc_ignore_off_page(lb, NORMAL));
 232 }
 233
 234 # if defined(__STDC__) || defined(__cplusplus)
 235   void * GC_malloc_atomic_ignore_off_page(size_t lb)
 236 # else
 237   char * GC_malloc_atomic_ignore_off_page(lb)
 238   register size_t lb;
 239 # endif
 240 {
 241     return((GC_PTR)GC_generic_malloc_ignore_off_page(lb, PTRFREE));
 242 }
 243
 244 /* Increment GC_words_allocd from code that doesn't have direct access  */
 245 /* to GC_arrays.                                                        */
 246 # ifdef __STDC__
 247 void GC_incr_words_allocd(size_t n)
 248 {
 249     GC_words_allocd += n;
 250 }
 251
 252 /* The same for GC_mem_freed.                           */
 253 void GC_incr_mem_freed(size_t n)
 254 {
 255     GC_mem_freed += n;
 256 }
 257 # endif /* __STDC__ */
 258
 259 /* Analogous to the above, but assumes a small object size, and         */
 260 /* bypasses MERGE_SIZES mechanism.  Used by gc_inline.h.                */
 261 ptr_t GC_generic_malloc_words_small_inner(lw, k)
 262 register word lw;
 263 register int k;
 264 {
 265 register ptr_t op;
 266 register ptr_t *opp;
 267 register struct obj_kind * kind = GC_obj_kinds + k;
 268
 269     opp = &(kind -> ok_freelist[lw]);
 270     if( (op = *opp) == 0 ) {
 271         if (!GC_is_initialized) {
 272             GC_init_inner();
 273         }
 274         if (kind -> ok_reclaim_list != 0 || GC_alloc_reclaim_list(kind)) {
 275             op = GC_clear_stack(GC_allocobj((word)lw, k));
 276         }
 277         if (op == 0) {
 278             UNLOCK();
 279             ENABLE_SIGNALS();
 280             return ((*GC_oom_fn)(WORDS_TO_BYTES(lw)));
 281         }
 282     }
 283     *opp = obj_link(op);
 284     obj_link(op) = 0;
 285     GC_words_allocd += lw;
 286     return((ptr_t)op);
 287 }
 288
 289 /* Analogous to the above, but assumes a small object size, and         */
 290 /* bypasses MERGE_SIZES mechanism.  Used by gc_inline.h.                */
 291 #ifdef __STDC__
 292      ptr_t GC_generic_malloc_words_small(size_t lw, int k)
 293 #else
 294      ptr_t GC_generic_malloc_words_small(lw, k)
 295      register word lw;
 296      register int k;
 297 #endif
 298 {
 299 register ptr_t op;
 300 DCL_LOCK_STATE;
 301
 302     if (GC_have_errors) GC_print_all_errors();
 303     GC_INVOKE_FINALIZERS();
 304     DISABLE_SIGNALS();
 305     LOCK();
 306     op = GC_generic_malloc_words_small_inner(lw, k);
 307     UNLOCK();
 308     ENABLE_SIGNALS();
 309     return((ptr_t)op);
 310 }
 311
 312 #if defined(THREADS) && !defined(SRC_M3)
 313
 314 extern signed_word GC_mem_found;   /* Protected by GC lock.  */
 315
 316 #ifdef PARALLEL_MARK
 317 volatile signed_word GC_words_allocd_tmp = 0;
 318                         /* Number of words of memory allocated since    */
 319                         /* we released the GC lock.  Instead of         */
 320                         /* reacquiring the GC lock just to add this in, */
 321                         /* we add it in the next time we reacquire      */
 322                         /* the lock.  (Atomically adding it doesn't     */
 323                         /* work, since we would have to atomically      */
 324                         /* update it in GC_malloc, which is too         */
 325                         /* expensive.                                   */
 326 #endif /* PARALLEL_MARK */
 327
 328 /* See reclaim.c: */
 329 extern ptr_t GC_reclaim_generic();
 330
 331 /* Return a list of 1 or more objects of the indicated size, linked     */
 332 /* through the first word in the object.  This has the advantage that   */
 333 /* it acquires the allocation lock only once, and may greatly reduce    */
 334 /* time wasted contending for the allocation lock.  Typical usage would */
 335 /* be in a thread that requires many items of the same size.  It would  */
 336 /* keep its own free list in thread-local storage, and call             */
 337 /* GC_malloc_many or friends to replenish it.  (We do not round up      */
 338 /* object sizes, since a call indicates the intention to consume many   */
 339 /* objects of exactly this size.)                                       */
 340 /* We return the free-list by assigning it to *result, since it is      */
 341 /* not safe to return, e.g. a linked list of pointer-free objects,      */
 342 /* since the collector would not retain the entire list if it were      */
 343 /* invoked just as we were returning.                                   */
 344 /* Note that the client should usually clear the link field.            */
 345 void GC_generic_malloc_many(lb, k, result)
 346 register word lb;
 347 register int k;
 348 ptr_t *result;
 349 {
 350 ptr_t op;
 351 ptr_t p;
 352 ptr_t *opp;
 353 word lw;
 354 word my_words_allocd = 0;
 355 struct obj_kind * ok = &(GC_obj_kinds[k]);
 356 DCL_LOCK_STATE;
 357
 358 #   if defined(GATHERSTATS) || defined(PARALLEL_MARK)
 359 #     define COUNT_ARG , &my_words_allocd
 360 #   else
 361 #     define COUNT_ARG
 362 #     define NEED_TO_COUNT
 363 #   endif
 364     if (!SMALL_OBJ(lb)) {
 365         op = GC_generic_malloc(lb, k);
 366         if(0 != op) obj_link(op) = 0;
 367         *result = op;
 368         return;
 369     }
 370     lw = ALIGNED_WORDS(lb);
 371     if (GC_have_errors) GC_print_all_errors();
 372     GC_INVOKE_FINALIZERS();
 373     DISABLE_SIGNALS();
 374     LOCK();
 375     if (!GC_is_initialized) GC_init_inner();
 376     /* Do our share of marking work */
 377       if (GC_incremental && !GC_dont_gc) {
 378         ENTER_GC();
 379         GC_collect_a_little_inner(1);
 380         EXIT_GC();
 381       }
 382     /* First see if we can reclaim a page of objects waiting to be */
 383     /* reclaimed.                                                  */
 384     {
 385         struct hblk ** rlh = ok -> ok_reclaim_list;
 386         struct hblk * hbp;
 387         hdr * hhdr;
 388
 389         rlh += lw;
 390         while ((hbp = *rlh) != 0) {
 391             hhdr = HDR(hbp);
 392             *rlh = hhdr -> hb_next;
 393             hhdr -> hb_last_reclaimed = (unsigned short) GC_gc_no;
 394 #           ifdef PARALLEL_MARK
 395                 {
 396                   signed_word my_words_allocd_tmp = GC_words_allocd_tmp;
 397
 398                   GC_ASSERT(my_words_allocd_tmp >= 0);
 399                   /* We only decrement it while holding the GC lock.    */
 400                   /* Thus we can't accidentally adjust it down in more  */
 401                   /* than one thread simultaneously.                    */
 402                   if (my_words_allocd_tmp != 0) {
 403                     (void)GC_atomic_add(
 404                                 (volatile GC_word *)(&GC_words_allocd_tmp),
 405                                 (GC_word)(-my_words_allocd_tmp));
 406                     GC_words_allocd += my_words_allocd_tmp;
 407                   }
 408                 }
 409                 GC_acquire_mark_lock();
 410                 ++ GC_fl_builder_count;
 411                 UNLOCK();
 412                 ENABLE_SIGNALS();
 413                 GC_release_mark_lock();
 414 #           endif
 415             op = GC_reclaim_generic(hbp, hhdr, lw,
 416                                     ok -> ok_init, 0 COUNT_ARG);
 417             if (op != 0) {
 418 #             ifdef NEED_TO_COUNT
 419                 /* We are neither gathering statistics, nor marking in  */
 420                 /* parallel.  Thus GC_reclaim_generic doesn't count     */
 421                 /* for us.                                              */
 422                 for (p = op; p != 0; p = obj_link(p)) {
 423                   my_words_allocd += lw;
 424                 }
 425 #             endif
 426 #             if defined(GATHERSTATS)
 427                 /* We also reclaimed memory, so we need to adjust       */
 428                 /* that count.                                          */
 429                 /* This should be atomic, so the results may be         */
 430                 /* inaccurate.                                          */
 431                 GC_mem_found += my_words_allocd;
 432 #             endif
 433 #             ifdef PARALLEL_MARK
 434                 *result = op;
 435                 (void)GC_atomic_add(
 436                                 (volatile GC_word *)(&GC_words_allocd_tmp),
 437                                 (GC_word)(my_words_allocd));
 438                 GC_acquire_mark_lock();
 439                 -- GC_fl_builder_count;
 440                 if (GC_fl_builder_count == 0) GC_notify_all_builder();
 441                 GC_release_mark_lock();
 442                 (void) GC_clear_stack(0);
 443                 return;
 444 #             else
 445                 GC_words_allocd += my_words_allocd;
 446                 goto out;
 447 #             endif
 448             }
 449 #           ifdef PARALLEL_MARK
 450               GC_acquire_mark_lock();
 451               -- GC_fl_builder_count;
 452               if (GC_fl_builder_count == 0) GC_notify_all_builder();
 453               GC_release_mark_lock();
 454               DISABLE_SIGNALS();
 455               LOCK();
 456               /* GC lock is needed for reclaim list access.     We      */
 457               /* must decrement fl_builder_count before reaquiring GC   */
 458               /* lock.  Hopefully this path is rare.                    */
 459 #           endif
 460         }
 461     }
 462     /* Next try to use prefix of global free list if there is one.      */
 463     /* We don't refill it, but we need to use it up before allocating   */
 464     /* a new block ourselves.                                           */
 465       opp = &(GC_obj_kinds[k].ok_freelist[lw]);
 466       if ( (op = *opp) != 0 ) {
 467         *opp = 0;
 468         my_words_allocd = 0;
 469         for (p = op; p != 0; p = obj_link(p)) {
 470           my_words_allocd += lw;
 471           if (my_words_allocd >= BODY_SZ) {
 472             *opp = obj_link(p);
 473             obj_link(p) = 0;
 474             break;
 475           }
 476         }
 477         GC_words_allocd += my_words_allocd;
 478         goto out;
 479       }
 480     /* Next try to allocate a new block worth of objects of this size.  */
 481     {
 482         struct hblk *h = GC_allochblk(lw, k, 0);
 483         if (h != 0) {
 484           if (IS_UNCOLLECTABLE(k)) GC_set_hdr_marks(HDR(h));
 485           GC_words_allocd += BYTES_TO_WORDS(HBLKSIZE)
 486                                - BYTES_TO_WORDS(HBLKSIZE) % lw;
 487 #         ifdef PARALLEL_MARK
 488             GC_acquire_mark_lock();
 489             ++ GC_fl_builder_count;
 490             UNLOCK();
 491             ENABLE_SIGNALS();
 492             GC_release_mark_lock();
 493 #         endif
 494
 495           op = GC_build_fl(h, lw, ok -> ok_init, 0);
 496 #         ifdef PARALLEL_MARK
 497             *result = op;
 498             GC_acquire_mark_lock();
 499             -- GC_fl_builder_count;
 500             if (GC_fl_builder_count == 0) GC_notify_all_builder();
 501             GC_release_mark_lock();
 502             (void) GC_clear_stack(0);
 503             return;
 504 #         else
 505             goto out;
 506 #         endif
 507         }
 508     }
 509
 510     /* As a last attempt, try allocating a single object.  Note that    */
 511     /* this may trigger a collection or expand the heap.                */
 512       op = GC_generic_malloc_inner(lb, k);
 513       if (0 != op) obj_link(op) = 0;
 514
 515   out:
 516     *result = op;
 517     UNLOCK();
 518     ENABLE_SIGNALS();
 519     (void) GC_clear_stack(0);
 520 }
 521
 522 GC_PTR GC_malloc_many(size_t lb)
 523 {
 524     ptr_t result;
 525     GC_generic_malloc_many(lb, NORMAL, &result);
 526     return result;
 527 }
 528
 529 /* Note that the "atomic" version of this would be unsafe, since the    */
 530 /* links would not be seen by the collector.                            */
 531 # endif
 532
 533 /* Allocate lb bytes of pointerful, traced, but not collectable data */
 534 # ifdef __STDC__
 535     GC_PTR GC_malloc_uncollectable(size_t lb)
 536 # else
 537     GC_PTR GC_malloc_uncollectable(lb)
 538     size_t lb;
 539 # endif
 540 {
 541 register ptr_t op;
 542 register ptr_t *opp;
 543 register word lw;
 544 DCL_LOCK_STATE;
 545
 546     if( SMALL_OBJ(lb) ) {
 547 #       ifdef MERGE_SIZES
 548           if (EXTRA_BYTES != 0 && lb != 0) lb--;
 549                   /* We don't need the extra byte, since this won't be  */
 550                   /* collected anyway.                                  */
 551           lw = GC_size_map[lb];
 552 #       else
 553           lw = ALIGNED_WORDS(lb);
 554 #       endif
 555         opp = &(GC_uobjfreelist[lw]);
 556         FASTLOCK();
 557         if( FASTLOCK_SUCCEEDED() && (op = *opp) != 0 ) {
 558             /* See above comment on signals.    */
 559             *opp = obj_link(op);
 560             obj_link(op) = 0;
 561             GC_words_allocd += lw;
 562             /* Mark bit ws already set on free list.  It will be        */
 563             /* cleared only temporarily during a collection, as a       */
 564             /* result of the normal free list mark bit clearing.        */
 565             GC_non_gc_bytes += WORDS_TO_BYTES(lw);
 566             FASTUNLOCK();
 567             return((GC_PTR) op);
 568         }
 569         FASTUNLOCK();
 570         op = (ptr_t)GC_generic_malloc((word)lb, UNCOLLECTABLE);
 571     } else {
 572         op = (ptr_t)GC_generic_malloc((word)lb, UNCOLLECTABLE);
 573     }
 574     if (0 == op) return(0);
 575     /* We don't need the lock here, since we have an undisguised        */
 576     /* pointer.  We do need to hold the lock while we adjust            */
 577     /* mark bits.                                                       */
 578     {
 579         register struct hblk * h;
 580
 581         h = HBLKPTR(op);
 582         lw = HDR(h) -> hb_sz;
 583
 584         DISABLE_SIGNALS();
 585         LOCK();
 586         GC_set_mark_bit(op);
 587         GC_non_gc_bytes += WORDS_TO_BYTES(lw);
 588         UNLOCK();
 589         ENABLE_SIGNALS();
 590         return((GC_PTR) op);
 591     }
 592 }
 593
 594 #ifdef __STDC__
 595 /* Not well tested nor integrated.      */
 596 /* Debug version is tricky and currently missing.       */
 597 #include <limits.h>
 598
 599 GC_PTR GC_memalign(size_t align, size_t lb)
 600 {
 601     size_t new_lb;
 602     size_t offset;
 603     ptr_t result;
 604
 605 #   ifdef ALIGN_DOUBLE
 606         if (align <= WORDS_TO_BYTES(2) && lb > align) return GC_malloc(lb);
 607 #   endif
 608     if (align <= WORDS_TO_BYTES(1)) return GC_malloc(lb);
 609     if (align >= HBLKSIZE/2 || lb >= HBLKSIZE/2) {
 610         if (align > HBLKSIZE) return GC_oom_fn(LONG_MAX-1024) /* Fail */;
 611         return GC_malloc(lb <= HBLKSIZE? HBLKSIZE : lb);
 612             /* Will be HBLKSIZE aligned.        */
 613     }
 614     /* We could also try to make sure that the real rounded-up object size */
 615     /* is a multiple of align.  That would be correct up to HBLKSIZE.      */
 616     new_lb = lb + align - 1;
 617     result = GC_malloc(new_lb);
 618     offset = (word)result % align;
 619     if (offset != 0) {
 620         offset = align - offset;
 621         if (!GC_all_interior_pointers) {
 622             if (offset >= VALID_OFFSET_SZ) return GC_malloc(HBLKSIZE);
 623             GC_register_displacement(offset);
 624         }
 625     }
 626     result = (GC_PTR) ((ptr_t)result + offset);
 627     GC_ASSERT((word)result % align == 0);
 628     return result;
 629 }
 630 #endif
 631
 632 # ifdef ATOMIC_UNCOLLECTABLE
 633 /* Allocate lb bytes of pointerfree, untraced, uncollectable data       */
 634 /* This is normally roughly equivalent to the system malloc.            */
 635 /* But it may be useful if malloc is redefined.                         */
 636 # ifdef __STDC__
 637     GC_PTR GC_malloc_atomic_uncollectable(size_t lb)
 638 # else
 639     GC_PTR GC_malloc_atomic_uncollectable(lb)
 640     size_t lb;
 641 # endif
 642 {
 643 register ptr_t op;
 644 register ptr_t *opp;
 645 register word lw;
 646 DCL_LOCK_STATE;
 647
 648     if( SMALL_OBJ(lb) ) {
 649 #       ifdef MERGE_SIZES
 650           if (EXTRA_BYTES != 0 && lb != 0) lb--;
 651                   /* We don't need the extra byte, since this won't be  */
 652                   /* collected anyway.                                  */
 653           lw = GC_size_map[lb];
 654 #       else
 655           lw = ALIGNED_WORDS(lb);
 656 #       endif
 657         opp = &(GC_auobjfreelist[lw]);
 658         FASTLOCK();
 659         if( FASTLOCK_SUCCEEDED() && (op = *opp) != 0 ) {
 660             /* See above comment on signals.    */
 661             *opp = obj_link(op);
 662             obj_link(op) = 0;
 663             GC_words_allocd += lw;
 664             /* Mark bit was already set while object was on free list. */
 665             GC_non_gc_bytes += WORDS_TO_BYTES(lw);
 666             FASTUNLOCK();
 667             return((GC_PTR) op);
 668         }
 669         FASTUNLOCK();
 670         op = (ptr_t)GC_generic_malloc((word)lb, AUNCOLLECTABLE);
 671     } else {
 672         op = (ptr_t)GC_generic_malloc((word)lb, AUNCOLLECTABLE);
 673     }
 674     if (0 == op) return(0);
 675     /* We don't need the lock here, since we have an undisguised        */
 676     /* pointer.  We do need to hold the lock while we adjust            */
 677     /* mark bits.                                                       */
 678     {
 679         register struct hblk * h;
 680
 681         h = HBLKPTR(op);
 682         lw = HDR(h) -> hb_sz;
 683
 684         DISABLE_SIGNALS();
 685         LOCK();
 686         GC_set_mark_bit(op);
 687         GC_non_gc_bytes += WORDS_TO_BYTES(lw);
 688         UNLOCK();
 689         ENABLE_SIGNALS();
 690         return((GC_PTR) op);
 691     }
 692 }
 693
 694 #endif /* ATOMIC_UNCOLLECTABLE */