libgc/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 /* Allocate memory such that only pointers to near the          */
 176 /* beginning of the object are considered.                      */
 177 /* We avoid holding allocation lock while we clear memory.      */
 178 ptr_t GC_generic_malloc_ignore_off_page(lb, k)
 179 register size_t lb;
 180 register int k;
 181 {
 182     register ptr_t result;
 183     word lw;
 184     word n_blocks;
 185     GC_bool init;
 186     DCL_LOCK_STATE;
 187
 188     if (SMALL_OBJ(lb))
 189         return(GC_generic_malloc((word)lb, k));
 190     lw = ROUNDED_UP_WORDS(lb);
 191     n_blocks = OBJ_SZ_TO_BLOCKS(lw);
 192     init = GC_obj_kinds[k].ok_init;
 193     if (GC_have_errors) GC_print_all_errors();
 194     GC_INVOKE_FINALIZERS();
 195     DISABLE_SIGNALS();
 196     LOCK();
 197     result = (ptr_t)GC_alloc_large(lw, k, IGNORE_OFF_PAGE);
 198     if (0 != result) {
 199         if (GC_debugging_started) {
 200             BZERO(result, n_blocks * HBLKSIZE);
 201         } else {
 202 #           ifdef THREADS
 203               /* Clear any memory that might be used for GC descriptors */
 204               /* before we release the lock.                          */
 205                 ((word *)result)[0] = 0;
 206                 ((word *)result)[1] = 0;
 207                 ((word *)result)[lw-1] = 0;
 208                 ((word *)result)[lw-2] = 0;
 209 #           endif
 210         }
 211     }
 212     GC_words_allocd += lw;
 213     UNLOCK();
 214     ENABLE_SIGNALS();
 215     if (0 == result) {
 216         return((*GC_oom_fn)(lb));
 217     } else {
 218         if (init && !GC_debugging_started) {
 219             BZERO(result, n_blocks * HBLKSIZE);
 220         }
 221         return(result);
 222     }
 223 }
 224
 225 # if defined(__STDC__) || defined(__cplusplus)
 226   void * GC_malloc_ignore_off_page(size_t lb)
 227 # else
 228   char * GC_malloc_ignore_off_page(lb)
 229   register size_t lb;
 230 # endif
 231 {
 232     return((GC_PTR)GC_generic_malloc_ignore_off_page(lb, NORMAL));
 233 }
 234
 235 # if defined(__STDC__) || defined(__cplusplus)
 236   void * GC_malloc_atomic_ignore_off_page(size_t lb)
 237 # else
 238   char * GC_malloc_atomic_ignore_off_page(lb)
 239   register size_t lb;
 240 # endif
 241 {
 242     return((GC_PTR)GC_generic_malloc_ignore_off_page(lb, PTRFREE));
 243 }
 244
 245 /* Increment GC_words_allocd from code that doesn't have direct access  */
 246 /* to GC_arrays.                                                        */
 247 # ifdef __STDC__
 248 void GC_incr_words_allocd(size_t n)
 249 {
 250     GC_words_allocd += n;
 251 }
 252
 253 /* The same for GC_mem_freed.                           */
 254 void GC_incr_mem_freed(size_t n)
 255 {
 256     GC_mem_freed += n;
 257 }
 258 # endif /* __STDC__ */
 259
 260 /* Analogous to the above, but assumes a small object size, and         */
 261 /* bypasses MERGE_SIZES mechanism.  Used by gc_inline.h.                */
 262 ptr_t GC_generic_malloc_words_small_inner(lw, k)
 263 register word lw;
 264 register int k;
 265 {
 266 register ptr_t op;
 267 register ptr_t *opp;
 268 register struct obj_kind * kind = GC_obj_kinds + k;
 269
 270     opp = &(kind -> ok_freelist[lw]);
 271     if( (op = *opp) == 0 ) {
 272         if (!GC_is_initialized) {
 273             GC_init_inner();
 274         }
 275         if (kind -> ok_reclaim_list != 0 || GC_alloc_reclaim_list(kind)) {
 276             op = GC_clear_stack(GC_allocobj((word)lw, k));
 277         }
 278         if (op == 0) {
 279             UNLOCK();
 280             ENABLE_SIGNALS();
 281             return ((*GC_oom_fn)(WORDS_TO_BYTES(lw)));
 282         }
 283     }
 284     *opp = obj_link(op);
 285     obj_link(op) = 0;
 286     GC_words_allocd += lw;
 287     return((ptr_t)op);
 288 }
 289
 290 /* Analogous to the above, but assumes a small object size, and         */
 291 /* bypasses MERGE_SIZES mechanism.  Used by gc_inline.h.                */
 292 #ifdef __STDC__
 293      ptr_t GC_generic_malloc_words_small(size_t lw, int k)
 294 #else
 295      ptr_t GC_generic_malloc_words_small(lw, k)
 296      register word lw;
 297      register int k;
 298 #endif
 299 {
 300 register ptr_t op;
 301 DCL_LOCK_STATE;
 302
 303     if (GC_have_errors) GC_print_all_errors();
 304     GC_INVOKE_FINALIZERS();
 305     DISABLE_SIGNALS();
 306     LOCK();
 307     op = GC_generic_malloc_words_small_inner(lw, k);
 308     UNLOCK();
 309     ENABLE_SIGNALS();
 310     return((ptr_t)op);
 311 }
 312
 313 #if defined(THREADS) && !defined(SRC_M3)
 314
 315 extern signed_word GC_mem_found;   /* Protected by GC lock.  */
 316
 317 #ifdef PARALLEL_MARK
 318 volatile signed_word GC_words_allocd_tmp = 0;
 319                         /* Number of words of memory allocated since    */
 320                         /* we released the GC lock.  Instead of         */
 321                         /* reacquiring the GC lock just to add this in, */
 322                         /* we add it in the next time we reacquire      */
 323                         /* the lock.  (Atomically adding it doesn't     */
 324                         /* work, since we would have to atomically      */
 325                         /* update it in GC_malloc, which is too         */
 326                         /* expensive.                                   */
 327 #endif /* PARALLEL_MARK */
 328
 329 /* See reclaim.c: */
 330 extern ptr_t GC_reclaim_generic();
 331
 332 /* Return a list of 1 or more objects of the indicated size, linked     */
 333 /* through the first word in the object.  This has the advantage that   */
 334 /* it acquires the allocation lock only once, and may greatly reduce    */
 335 /* time wasted contending for the allocation lock.  Typical usage would */
 336 /* be in a thread that requires many items of the same size.  It would  */
 337 /* keep its own free list in thread-local storage, and call             */
 338 /* GC_malloc_many or friends to replenish it.  (We do not round up      */
 339 /* object sizes, since a call indicates the intention to consume many   */
 340 /* objects of exactly this size.)                                       */
 341 /* We return the free-list by assigning it to *result, since it is      */
 342 /* not safe to return, e.g. a linked list of pointer-free objects,      */
 343 /* since the collector would not retain the entire list if it were      */
 344 /* invoked just as we were returning.                                   */
 345 /* Note that the client should usually clear the link field.            */
 346 void GC_generic_malloc_many(lb, k, result)
 347 register word lb;
 348 register int k;
 349 ptr_t *result;
 350 {
 351 ptr_t op;
 352 ptr_t p;
 353 ptr_t *opp;
 354 word lw;
 355 word my_words_allocd = 0;
 356 struct obj_kind * ok = &(GC_obj_kinds[k]);
 357 DCL_LOCK_STATE;
 358
 359 #   if defined(GATHERSTATS) || defined(PARALLEL_MARK)
 360 #     define COUNT_ARG , &my_words_allocd
 361 #   else
 362 #     define COUNT_ARG
 363 #     define NEED_TO_COUNT
 364 #   endif
 365     if (!SMALL_OBJ(lb)) {
 366         op = GC_generic_malloc(lb, k);
 367         if(0 != op) obj_link(op) = 0;
 368         *result = op;
 369         return;
 370     }
 371     lw = ALIGNED_WORDS(lb);
 372     if (GC_have_errors) GC_print_all_errors();
 373     GC_INVOKE_FINALIZERS();
 374     DISABLE_SIGNALS();
 375     LOCK();
 376     if (!GC_is_initialized) GC_init_inner();
 377     /* Do our share of marking work */
 378       if (GC_incremental && !GC_dont_gc) {
 379         ENTER_GC();
 380         GC_collect_a_little_inner(1);
 381         EXIT_GC();
 382       }
 383     /* First see if we can reclaim a page of objects waiting to be */
 384     /* reclaimed.                                                  */
 385     {
 386         struct hblk ** rlh = ok -> ok_reclaim_list;
 387         struct hblk * hbp;
 388         hdr * hhdr;
 389
 390         rlh += lw;
 391         while ((hbp = *rlh) != 0) {
 392             hhdr = HDR(hbp);
 393             *rlh = hhdr -> hb_next;
 394             hhdr -> hb_last_reclaimed = (unsigned short) GC_gc_no;
 395 #           ifdef PARALLEL_MARK
 396                 {
 397                   signed_word my_words_allocd_tmp = GC_words_allocd_tmp;
 398
 399                   GC_ASSERT(my_words_allocd_tmp >= 0);
 400                   /* We only decrement it while holding the GC lock.    */
 401                   /* Thus we can't accidentally adjust it down in more  */
 402                   /* than one thread simultaneously.                    */
 403                   if (my_words_allocd_tmp != 0) {
 404                     (void)GC_atomic_add(
 405                                 (volatile GC_word *)(&GC_words_allocd_tmp),
 406                                 (GC_word)(-my_words_allocd_tmp));
 407                     GC_words_allocd += my_words_allocd_tmp;
 408                   }
 409                 }
 410                 GC_acquire_mark_lock();
 411                 ++ GC_fl_builder_count;
 412                 UNLOCK();
 413                 ENABLE_SIGNALS();
 414                 GC_release_mark_lock();
 415 #           endif
 416             op = GC_reclaim_generic(hbp, hhdr, lw,
 417                                     ok -> ok_init, 0 COUNT_ARG);
 418             if (op != 0) {
 419 #             ifdef NEED_TO_COUNT
 420                 /* We are neither gathering statistics, nor marking in  */
 421                 /* parallel.  Thus GC_reclaim_generic doesn't count     */
 422                 /* for us.                                              */
 423                 for (p = op; p != 0; p = obj_link(p)) {
 424                   my_words_allocd += lw;
 425                 }
 426 #             endif
 427 #             if defined(GATHERSTATS)
 428                 /* We also reclaimed memory, so we need to adjust       */
 429                 /* that count.                                          */
 430                 /* This should be atomic, so the results may be         */
 431                 /* inaccurate.                                          */
 432                 GC_mem_found += my_words_allocd;
 433 #             endif
 434 #             ifdef PARALLEL_MARK
 435                 *result = op;
 436                 (void)GC_atomic_add(
 437                                 (volatile GC_word *)(&GC_words_allocd_tmp),
 438                                 (GC_word)(my_words_allocd));
 439                 GC_acquire_mark_lock();
 440                 -- GC_fl_builder_count;
 441                 if (GC_fl_builder_count == 0) GC_notify_all_builder();
 442                 GC_release_mark_lock();
 443                 (void) GC_clear_stack(0);
 444                 return;
 445 #             else
 446                 GC_words_allocd += my_words_allocd;
 447                 goto out;
 448 #             endif
 449             }
 450 #           ifdef PARALLEL_MARK
 451               GC_acquire_mark_lock();
 452               -- GC_fl_builder_count;
 453               if (GC_fl_builder_count == 0) GC_notify_all_builder();
 454               GC_release_mark_lock();
 455               DISABLE_SIGNALS();
 456               LOCK();
 457               /* GC lock is needed for reclaim list access.     We      */
 458               /* must decrement fl_builder_count before reaquiring GC   */
 459               /* lock.  Hopefully this path is rare.                    */
 460 #           endif
 461         }
 462     }
 463     /* Next try to use prefix of global free list if there is one.      */
 464     /* We don't refill it, but we need to use it up before allocating   */
 465     /* a new block ourselves.                                           */
 466       opp = &(GC_obj_kinds[k].ok_freelist[lw]);
 467       if ( (op = *opp) != 0 ) {
 468         *opp = 0;
 469         my_words_allocd = 0;
 470         for (p = op; p != 0; p = obj_link(p)) {
 471           my_words_allocd += lw;
 472           if (my_words_allocd >= BODY_SZ) {
 473             *opp = obj_link(p);
 474             obj_link(p) = 0;
 475             break;
 476           }
 477         }
 478         GC_words_allocd += my_words_allocd;
 479         goto out;
 480       }
 481     /* Next try to allocate a new block worth of objects of this size.  */
 482     {
 483         struct hblk *h = GC_allochblk(lw, k, 0);
 484         if (h != 0) {
 485           if (IS_UNCOLLECTABLE(k)) GC_set_hdr_marks(HDR(h));
 486           GC_words_allocd += BYTES_TO_WORDS(HBLKSIZE)
 487                                - BYTES_TO_WORDS(HBLKSIZE) % lw;
 488 #         ifdef PARALLEL_MARK
 489             GC_acquire_mark_lock();
 490             ++ GC_fl_builder_count;
 491             UNLOCK();
 492             ENABLE_SIGNALS();
 493             GC_release_mark_lock();
 494 #         endif
 495
 496           op = GC_build_fl(h, lw, ok -> ok_init, 0);
 497 #         ifdef PARALLEL_MARK
 498             *result = op;
 499             GC_acquire_mark_lock();
 500             -- GC_fl_builder_count;
 501             if (GC_fl_builder_count == 0) GC_notify_all_builder();
 502             GC_release_mark_lock();
 503             (void) GC_clear_stack(0);
 504             return;
 505 #         else
 506             goto out;
 507 #         endif
 508         }
 509     }
 510
 511     /* As a last attempt, try allocating a single object.  Note that    */
 512     /* this may trigger a collection or expand the heap.                */
 513       op = GC_generic_malloc_inner(lb, k);
 514       if (0 != op) obj_link(op) = 0;
 515
 516   out:
 517     *result = op;
 518     UNLOCK();
 519     ENABLE_SIGNALS();
 520     (void) GC_clear_stack(0);
 521 }
 522
 523 GC_PTR GC_malloc_many(size_t lb)
 524 {
 525     ptr_t result;
 526     GC_generic_malloc_many(lb, NORMAL, &result);
 527     return result;
 528 }
 529
 530 /* Note that the "atomic" version of this would be unsafe, since the    */
 531 /* links would not be seen by the collector.                            */
 532 # endif
 533
 534 /* Allocate lb bytes of pointerful, traced, but not collectable data */
 535 # ifdef __STDC__
 536     GC_PTR GC_malloc_uncollectable(size_t lb)
 537 # else
 538     GC_PTR GC_malloc_uncollectable(lb)
 539     size_t lb;
 540 # endif
 541 {
 542 register ptr_t op;
 543 register ptr_t *opp;
 544 register word lw;
 545 DCL_LOCK_STATE;
 546
 547     if( SMALL_OBJ(lb) ) {
 548 #       ifdef MERGE_SIZES
 549           if (EXTRA_BYTES != 0 && lb != 0) lb--;
 550                   /* We don't need the extra byte, since this won't be  */
 551                   /* collected anyway.                                  */
 552           lw = GC_size_map[lb];
 553 #       else
 554           lw = ALIGNED_WORDS(lb);
 555 #       endif
 556         opp = &(GC_uobjfreelist[lw]);
 557         FASTLOCK();
 558         if( FASTLOCK_SUCCEEDED() && (op = *opp) != 0 ) {
 559             /* See above comment on signals.    */
 560             *opp = obj_link(op);
 561             obj_link(op) = 0;
 562             GC_words_allocd += lw;
 563             /* Mark bit ws already set on free list.  It will be        */
 564             /* cleared only temporarily during a collection, as a       */
 565             /* result of the normal free list mark bit clearing.        */
 566             GC_non_gc_bytes += WORDS_TO_BYTES(lw);
 567             FASTUNLOCK();
 568             return((GC_PTR) op);
 569         }
 570         FASTUNLOCK();
 571         op = (ptr_t)GC_generic_malloc((word)lb, UNCOLLECTABLE);
 572     } else {
 573         op = (ptr_t)GC_generic_malloc((word)lb, UNCOLLECTABLE);
 574     }
 575     if (0 == op) return(0);
 576     /* We don't need the lock here, since we have an undisguised        */
 577     /* pointer.  We do need to hold the lock while we adjust            */
 578     /* mark bits.                                                       */
 579     {
 580         register struct hblk * h;
 581
 582         h = HBLKPTR(op);
 583         lw = HDR(h) -> hb_sz;
 584
 585         DISABLE_SIGNALS();
 586         LOCK();
 587         GC_set_mark_bit(op);
 588         GC_non_gc_bytes += WORDS_TO_BYTES(lw);
 589         UNLOCK();
 590         ENABLE_SIGNALS();
 591         return((GC_PTR) op);
 592     }
 593 }
 594
 595 #ifdef __STDC__
 596 /* Not well tested nor integrated.      */
 597 /* Debug version is tricky and currently missing.       */
 598 #include <limits.h>
 599
 600 GC_PTR GC_memalign(size_t align, size_t lb)
 601 {
 602     size_t new_lb;
 603     size_t offset;
 604     ptr_t result;
 605
 606 #   ifdef ALIGN_DOUBLE
 607         if (align <= WORDS_TO_BYTES(2) && lb > align) return GC_malloc(lb);
 608 #   endif
 609     if (align <= WORDS_TO_BYTES(1)) return GC_malloc(lb);
 610     if (align >= HBLKSIZE/2 || lb >= HBLKSIZE/2) {
 611         if (align > HBLKSIZE) return GC_oom_fn(LONG_MAX-1024) /* Fail */;
 612         return GC_malloc(lb <= HBLKSIZE? HBLKSIZE : lb);
 613             /* Will be HBLKSIZE aligned.        */
 614     }
 615     /* We could also try to make sure that the real rounded-up object size */
 616     /* is a multiple of align.  That would be correct up to HBLKSIZE.      */
 617     new_lb = lb + align - 1;
 618     result = GC_malloc(new_lb);
 619     offset = (word)result % align;
 620     if (offset != 0) {
 621         offset = align - offset;
 622         if (!GC_all_interior_pointers) {
 623             if (offset >= VALID_OFFSET_SZ) return GC_malloc(HBLKSIZE);
 624             GC_register_displacement(offset);
 625         }
 626     }
 627     result = (GC_PTR) ((ptr_t)result + offset);
 628     GC_ASSERT((word)result % align == 0);
 629     return result;
 630 }
 631 #endif
 632
 633 # ifdef ATOMIC_UNCOLLECTABLE
 634 /* Allocate lb bytes of pointerfree, untraced, uncollectable data       */
 635 /* This is normally roughly equivalent to the system malloc.            */
 636 /* But it may be useful if malloc is redefined.                         */
 637 # ifdef __STDC__
 638     GC_PTR GC_malloc_atomic_uncollectable(size_t lb)
 639 # else
 640     GC_PTR GC_malloc_atomic_uncollectable(lb)
 641     size_t lb;
 642 # endif
 643 {
 644 register ptr_t op;
 645 register ptr_t *opp;
 646 register word lw;
 647 DCL_LOCK_STATE;
 648
 649     if( SMALL_OBJ(lb) ) {
 650 #       ifdef MERGE_SIZES
 651           if (EXTRA_BYTES != 0 && lb != 0) lb--;
 652                   /* We don't need the extra byte, since this won't be  */
 653                   /* collected anyway.                                  */
 654           lw = GC_size_map[lb];
 655 #       else
 656           lw = ALIGNED_WORDS(lb);
 657 #       endif
 658         opp = &(GC_auobjfreelist[lw]);
 659         FASTLOCK();
 660         if( FASTLOCK_SUCCEEDED() && (op = *opp) != 0 ) {
 661             /* See above comment on signals.    */
 662             *opp = obj_link(op);
 663             obj_link(op) = 0;
 664             GC_words_allocd += lw;
 665             /* Mark bit was already set while object was on free list. */
 666             GC_non_gc_bytes += WORDS_TO_BYTES(lw);
 667             FASTUNLOCK();
 668             return((GC_PTR) op);
 669         }
 670         FASTUNLOCK();
 671         op = (ptr_t)GC_generic_malloc((word)lb, AUNCOLLECTABLE);
 672     } else {
 673         op = (ptr_t)GC_generic_malloc((word)lb, AUNCOLLECTABLE);
 674     }
 675     if (0 == op) return(0);
 676     /* We don't need the lock here, since we have an undisguised        */
 677     /* pointer.  We do need to hold the lock while we adjust            */
 678     /* mark bits.                                                       */
 679     {
 680         register struct hblk * h;
 681
 682         h = HBLKPTR(op);
 683         lw = HDR(h) -> hb_sz;
 684
 685         DISABLE_SIGNALS();
 686         LOCK();
 687         GC_set_mark_bit(op);
 688         GC_non_gc_bytes += WORDS_TO_BYTES(lw);
 689         UNLOCK();
 690         ENABLE_SIGNALS();
 691         return((GC_PTR) op);
 692     }
 693 }
 694
 695 #endif /* ATOMIC_UNCOLLECTABLE */