1 /* -----------------------------------------------------------------------------
2 * $Id: Storage.c,v 1.76 2003/02/01 09:10:17 mthomas Exp $
4 * (c) The GHC Team, 1998-1999
6 * Storage manager front end
8 * ---------------------------------------------------------------------------*/
10 #include "PosixSource.h"
16 #include "BlockAlloc.h"
24 #include "OSThreads.h"
25 #include "StoragePriv.h"
27 #include "RetainerProfile.h" // for counting memory blocks (memInventory)
32 StgClosure *caf_list = NULL;
34 bdescr *small_alloc_list; /* allocate()d small objects */
35 bdescr *pinned_object_block; /* allocate pinned objects into this block */
36 nat alloc_blocks; /* number of allocate()d blocks since GC */
37 nat alloc_blocks_lim; /* approximate limit on alloc_blocks */
39 StgPtr alloc_Hp = NULL; /* next free byte in small_alloc_list */
40 StgPtr alloc_HpLim = NULL; /* end of block at small_alloc_list */
42 generation *generations = NULL; /* all the generations */
43 generation *g0 = NULL; /* generation 0, for convenience */
44 generation *oldest_gen = NULL; /* oldest generation, for convenience */
45 step *g0s0 = NULL; /* generation 0, step 0, for convenience */
47 lnat total_allocated = 0; /* total memory allocated during run */
50 * Storage manager mutex: protects all the above state from
51 * simultaneous access by two STG threads.
54 Mutex sm_mutex = INIT_MUTEX_VAR;
60 static void *stgAllocForGMP (size_t size_in_bytes);
61 static void *stgReallocForGMP (void *ptr, size_t old_size, size_t new_size);
62 static void stgDeallocForGMP (void *ptr, size_t size);
71 if (generations != NULL) {
72 // multi-init protection
76 /* Sanity check to make sure the LOOKS_LIKE_ macros appear to be
77 * doing something reasonable.
79 ASSERT(LOOKS_LIKE_INFO_PTR(&stg_BLACKHOLE_info));
80 ASSERT(LOOKS_LIKE_CLOSURE_PTR(&stg_dummy_ret_closure));
81 ASSERT(!HEAP_ALLOCED(&stg_dummy_ret_closure));
83 if (RtsFlags.GcFlags.maxHeapSize != 0 &&
84 RtsFlags.GcFlags.heapSizeSuggestion >
85 RtsFlags.GcFlags.maxHeapSize) {
86 RtsFlags.GcFlags.maxHeapSize = RtsFlags.GcFlags.heapSizeSuggestion;
89 if (RtsFlags.GcFlags.maxHeapSize != 0 &&
90 RtsFlags.GcFlags.minAllocAreaSize >
91 RtsFlags.GcFlags.maxHeapSize) {
92 prog_belch("maximum heap size (-M) is smaller than minimum alloc area size (-A)");
99 initCondition(&sm_mutex);
102 /* allocate generation info array */
103 generations = (generation *)stgMallocBytes(RtsFlags.GcFlags.generations
104 * sizeof(struct _generation),
105 "initStorage: gens");
107 /* Initialise all generations */
108 for(g = 0; g < RtsFlags.GcFlags.generations; g++) {
109 gen = &generations[g];
111 gen->mut_list = END_MUT_LIST;
112 gen->mut_once_list = END_MUT_LIST;
113 gen->collections = 0;
114 gen->failed_promotions = 0;
118 /* A couple of convenience pointers */
119 g0 = &generations[0];
120 oldest_gen = &generations[RtsFlags.GcFlags.generations-1];
122 /* Allocate step structures in each generation */
123 if (RtsFlags.GcFlags.generations > 1) {
124 /* Only for multiple-generations */
126 /* Oldest generation: one step */
127 oldest_gen->n_steps = 1;
129 stgMallocBytes(1 * sizeof(struct _step), "initStorage: last step");
131 /* set up all except the oldest generation with 2 steps */
132 for(g = 0; g < RtsFlags.GcFlags.generations-1; g++) {
133 generations[g].n_steps = RtsFlags.GcFlags.steps;
134 generations[g].steps =
135 stgMallocBytes (RtsFlags.GcFlags.steps * sizeof(struct _step),
136 "initStorage: steps");
140 /* single generation, i.e. a two-space collector */
142 g0->steps = stgMallocBytes (sizeof(struct _step), "initStorage: steps");
145 /* Initialise all steps */
146 for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
147 for (s = 0; s < generations[g].n_steps; s++) {
148 stp = &generations[g].steps[s];
151 stp->n_to_blocks = 0;
153 stp->gen = &generations[g];
160 stp->large_objects = NULL;
161 stp->n_large_blocks = 0;
162 stp->new_large_objects = NULL;
163 stp->scavenged_large_objects = NULL;
164 stp->n_scavenged_large_blocks = 0;
165 stp->is_compacted = 0;
170 /* Set up the destination pointers in each younger gen. step */
171 for (g = 0; g < RtsFlags.GcFlags.generations-1; g++) {
172 for (s = 0; s < generations[g].n_steps-1; s++) {
173 generations[g].steps[s].to = &generations[g].steps[s+1];
175 generations[g].steps[s].to = &generations[g+1].steps[0];
178 /* The oldest generation has one step and it is compacted. */
179 if (RtsFlags.GcFlags.compact) {
180 if (RtsFlags.GcFlags.generations == 1) {
181 belch("WARNING: compaction is incompatible with -G1; disabled");
183 oldest_gen->steps[0].is_compacted = 1;
186 oldest_gen->steps[0].to = &oldest_gen->steps[0];
188 /* generation 0 is special: that's the nursery */
189 generations[0].max_blocks = 0;
191 /* G0S0: the allocation area. Policy: keep the allocation area
192 * small to begin with, even if we have a large suggested heap
193 * size. Reason: we're going to do a major collection first, and we
194 * don't want it to be a big one. This vague idea is borne out by
195 * rigorous experimental evidence.
197 g0s0 = &generations[0].steps[0];
201 weak_ptr_list = NULL;
204 /* initialise the allocate() interface */
205 small_alloc_list = NULL;
207 alloc_blocks_lim = RtsFlags.GcFlags.minAllocAreaSize;
209 /* Tell GNU multi-precision pkg about our custom alloc functions */
210 mp_set_memory_functions(stgAllocForGMP, stgReallocForGMP, stgDeallocForGMP);
213 initMutex(&sm_mutex);
216 IF_DEBUG(gc, statDescribeGens());
222 stat_exit(calcAllocated());
225 /* -----------------------------------------------------------------------------
228 The entry code for every CAF does the following:
230 - builds a CAF_BLACKHOLE in the heap
231 - pushes an update frame pointing to the CAF_BLACKHOLE
232 - invokes UPD_CAF(), which:
233 - calls newCaf, below
234 - updates the CAF with a static indirection to the CAF_BLACKHOLE
236 Why do we build a BLACKHOLE in the heap rather than just updating
237 the thunk directly? It's so that we only need one kind of update
238 frame - otherwise we'd need a static version of the update frame too.
240 newCaf() does the following:
242 - it puts the CAF on the oldest generation's mut-once list.
243 This is so that we can treat the CAF as a root when collecting
246 For GHCI, we have additional requirements when dealing with CAFs:
248 - we must *retain* all dynamically-loaded CAFs ever entered,
249 just in case we need them again.
250 - we must be able to *revert* CAFs that have been evaluated, to
251 their pre-evaluated form.
253 To do this, we use an additional CAF list. When newCaf() is
254 called on a dynamically-loaded CAF, we add it to the CAF list
255 instead of the old-generation mutable list, and save away its
256 old info pointer (in caf->saved_info) for later reversion.
258 To revert all the CAFs, we traverse the CAF list and reset the
259 info pointer to caf->saved_info, then throw away the CAF list.
260 (see GC.c:revertCAFs()).
264 -------------------------------------------------------------------------- */
267 newCAF(StgClosure* caf)
269 /* Put this CAF on the mutable list for the old generation.
270 * This is a HACK - the IND_STATIC closure doesn't really have
271 * a mut_link field, but we pretend it has - in fact we re-use
272 * the STATIC_LINK field for the time being, because when we
273 * come to do a major GC we won't need the mut_link field
274 * any more and can use it as a STATIC_LINK.
278 ((StgIndStatic *)caf)->saved_info = NULL;
279 ((StgMutClosure *)caf)->mut_link = oldest_gen->mut_once_list;
280 oldest_gen->mut_once_list = (StgMutClosure *)caf;
285 /* If we are PAR or DIST then we never forget a CAF */
287 //belch("<##> Globalising CAF %08x %s",caf,info_type(caf));
288 newGA=makeGlobal(caf,rtsTrue); /*given full weight*/
294 // An alternate version of newCaf which is used for dynamically loaded
295 // object code in GHCi. In this case we want to retain *all* CAFs in
296 // the object code, because they might be demanded at any time from an
297 // expression evaluated on the command line.
299 // The linker hackily arranges that references to newCaf from dynamic
300 // code end up pointing to newDynCAF.
302 newDynCAF(StgClosure *caf)
306 ((StgIndStatic *)caf)->saved_info = (StgInfoTable *)caf->header.info;
307 ((StgIndStatic *)caf)->static_link = caf_list;
313 /* -----------------------------------------------------------------------------
315 -------------------------------------------------------------------------- */
318 allocNurseries( void )
327 for (cap = free_capabilities; cap != NULL; cap = cap->link) {
328 cap->r.rNursery = allocNursery(NULL, RtsFlags.GcFlags.minAllocAreaSize);
329 cap->r.rCurrentNursery = cap->r.rNursery;
330 for (bd = cap->r.rNursery; bd != NULL; bd = bd->link) {
331 bd->u.back = (bdescr *)cap;
334 /* Set the back links to be equal to the Capability,
335 * so we can do slightly better informed locking.
339 g0s0->blocks = allocNursery(NULL, RtsFlags.GcFlags.minAllocAreaSize);
340 g0s0->n_blocks = RtsFlags.GcFlags.minAllocAreaSize;
341 g0s0->to_blocks = NULL;
342 g0s0->n_to_blocks = 0;
343 MainCapability.r.rNursery = g0s0->blocks;
344 MainCapability.r.rCurrentNursery = g0s0->blocks;
345 /* hp, hpLim, hp_bd, to_space etc. aren't used in G0S0 */
350 resetNurseries( void )
356 /* All tasks must be stopped */
357 ASSERT(n_free_capabilities == RtsFlags.ParFlags.nNodes);
359 for (cap = free_capabilities; cap != NULL; cap = cap->link) {
360 for (bd = cap->r.rNursery; bd; bd = bd->link) {
361 bd->free = bd->start;
362 ASSERT(bd->gen_no == 0);
363 ASSERT(bd->step == g0s0);
364 IF_DEBUG(sanity,memset(bd->start, 0xaa, BLOCK_SIZE));
366 cap->r.rCurrentNursery = cap->r.rNursery;
369 for (bd = g0s0->blocks; bd; bd = bd->link) {
370 bd->free = bd->start;
371 ASSERT(bd->gen_no == 0);
372 ASSERT(bd->step == g0s0);
373 IF_DEBUG(sanity,memset(bd->start, 0xaa, BLOCK_SIZE));
375 MainCapability.r.rNursery = g0s0->blocks;
376 MainCapability.r.rCurrentNursery = g0s0->blocks;
381 allocNursery (bdescr *tail, nat blocks)
386 // Allocate a nursery: we allocate fresh blocks one at a time and
387 // cons them on to the front of the list, not forgetting to update
388 // the back pointer on the tail of the list to point to the new block.
389 for (i=0; i < blocks; i++) {
392 processNursery() in LdvProfile.c assumes that every block group in
393 the nursery contains only a single block. So, if a block group is
394 given multiple blocks, change processNursery() accordingly.
398 // double-link the nursery: we might need to insert blocks
405 bd->free = bd->start;
413 resizeNursery ( nat blocks )
419 barf("resizeNursery: can't resize in SMP mode");
422 nursery_blocks = g0s0->n_blocks;
423 if (nursery_blocks == blocks) {
427 else if (nursery_blocks < blocks) {
428 IF_DEBUG(gc, fprintf(stderr, "Increasing size of nursery to %d blocks\n",
430 g0s0->blocks = allocNursery(g0s0->blocks, blocks-nursery_blocks);
436 IF_DEBUG(gc, fprintf(stderr, "Decreasing size of nursery to %d blocks\n",
440 while (nursery_blocks > blocks) {
442 next_bd->u.back = NULL;
443 nursery_blocks -= bd->blocks; // might be a large block
448 // might have gone just under, by freeing a large block, so make
449 // up the difference.
450 if (nursery_blocks < blocks) {
451 g0s0->blocks = allocNursery(g0s0->blocks, blocks-nursery_blocks);
455 g0s0->n_blocks = blocks;
456 ASSERT(countBlocks(g0s0->blocks) == g0s0->n_blocks);
459 /* -----------------------------------------------------------------------------
460 The allocate() interface
462 allocate(n) always succeeds, and returns a chunk of memory n words
463 long. n can be larger than the size of a block if necessary, in
464 which case a contiguous block group will be allocated.
465 -------------------------------------------------------------------------- */
475 TICK_ALLOC_HEAP_NOCTR(n);
478 /* big allocation (>LARGE_OBJECT_THRESHOLD) */
479 /* ToDo: allocate directly into generation 1 */
480 if (n >= LARGE_OBJECT_THRESHOLD/sizeof(W_)) {
481 nat req_blocks = (lnat)BLOCK_ROUND_UP(n*sizeof(W_)) / BLOCK_SIZE;
482 bd = allocGroup(req_blocks);
483 dbl_link_onto(bd, &g0s0->large_objects);
486 bd->flags = BF_LARGE;
487 bd->free = bd->start + n;
488 /* don't add these blocks to alloc_blocks, since we're assuming
489 * that large objects are likely to remain live for quite a while
490 * (eg. running threads), so garbage collecting early won't make
493 alloc_blocks += req_blocks;
497 /* small allocation (<LARGE_OBJECT_THRESHOLD) */
498 } else if (small_alloc_list == NULL || alloc_Hp + n > alloc_HpLim) {
499 if (small_alloc_list) {
500 small_alloc_list->free = alloc_Hp;
503 bd->link = small_alloc_list;
504 small_alloc_list = bd;
508 alloc_Hp = bd->start;
509 alloc_HpLim = bd->start + BLOCK_SIZE_W;
520 allocated_bytes( void )
524 allocated = alloc_blocks * BLOCK_SIZE_W - (alloc_HpLim - alloc_Hp);
525 if (pinned_object_block != NULL) {
526 allocated -= (pinned_object_block->start + BLOCK_SIZE_W) -
527 pinned_object_block->free;
534 tidyAllocateLists (void)
536 if (small_alloc_list != NULL) {
537 ASSERT(alloc_Hp >= small_alloc_list->start &&
538 alloc_Hp <= small_alloc_list->start + BLOCK_SIZE);
539 small_alloc_list->free = alloc_Hp;
543 /* ---------------------------------------------------------------------------
544 Allocate a fixed/pinned object.
546 We allocate small pinned objects into a single block, allocating a
547 new block when the current one overflows. The block is chained
548 onto the large_object_list of generation 0 step 0.
550 NOTE: The GC can't in general handle pinned objects. This
551 interface is only safe to use for ByteArrays, which have no
552 pointers and don't require scavenging. It works because the
553 block's descriptor has the BF_LARGE flag set, so the block is
554 treated as a large object and chained onto various lists, rather
555 than the individual objects being copied. However, when it comes
556 to scavenge the block, the GC will only scavenge the first object.
557 The reason is that the GC can't linearly scan a block of pinned
558 objects at the moment (doing so would require using the
559 mostly-copying techniques). But since we're restricting ourselves
560 to pinned ByteArrays, not scavenging is ok.
562 This function is called by newPinnedByteArray# which immediately
563 fills the allocated memory with a MutableByteArray#.
564 ------------------------------------------------------------------------- */
567 allocatePinned( nat n )
570 bdescr *bd = pinned_object_block;
574 TICK_ALLOC_HEAP_NOCTR(n);
577 // If the request is for a large object, then allocate()
578 // will give us a pinned object anyway.
579 if (n >= LARGE_OBJECT_THRESHOLD/sizeof(W_)) {
584 // we always return 8-byte aligned memory. bd->free must be
585 // 8-byte aligned to begin with, so we just round up n to
586 // the nearest multiple of 8 bytes.
587 if (sizeof(StgWord) == 4) {
591 // If we don't have a block of pinned objects yet, or the current
592 // one isn't large enough to hold the new object, allocate a new one.
593 if (bd == NULL || (bd->free + n) > (bd->start + BLOCK_SIZE_W)) {
594 pinned_object_block = bd = allocBlock();
595 dbl_link_onto(bd, &g0s0->large_objects);
598 bd->flags = BF_LARGE;
599 bd->free = bd->start;
609 /* -----------------------------------------------------------------------------
610 Allocation functions for GMP.
612 These all use the allocate() interface - we can't have any garbage
613 collection going on during a gmp operation, so we use allocate()
614 which always succeeds. The gmp operations which might need to
615 allocate will ask the storage manager (via doYouWantToGC()) whether
616 a garbage collection is required, in case we get into a loop doing
617 only allocate() style allocation.
618 -------------------------------------------------------------------------- */
621 stgAllocForGMP (size_t size_in_bytes)
624 nat data_size_in_words, total_size_in_words;
626 /* round up to a whole number of words */
627 data_size_in_words = (size_in_bytes + sizeof(W_) + 1) / sizeof(W_);
628 total_size_in_words = sizeofW(StgArrWords) + data_size_in_words;
630 /* allocate and fill it in. */
631 arr = (StgArrWords *)allocate(total_size_in_words);
632 SET_ARR_HDR(arr, &stg_ARR_WORDS_info, CCCS, data_size_in_words);
634 /* and return a ptr to the goods inside the array */
635 return(BYTE_ARR_CTS(arr));
639 stgReallocForGMP (void *ptr, size_t old_size, size_t new_size)
641 void *new_stuff_ptr = stgAllocForGMP(new_size);
643 char *p = (char *) ptr;
644 char *q = (char *) new_stuff_ptr;
646 for (; i < old_size; i++, p++, q++) {
650 return(new_stuff_ptr);
654 stgDeallocForGMP (void *ptr STG_UNUSED,
655 size_t size STG_UNUSED)
657 /* easy for us: the garbage collector does the dealloc'n */
660 /* -----------------------------------------------------------------------------
662 * -------------------------------------------------------------------------- */
664 /* -----------------------------------------------------------------------------
667 * Approximate how much we've allocated: number of blocks in the
668 * nursery + blocks allocated via allocate() - unused nusery blocks.
669 * This leaves a little slop at the end of each block, and doesn't
670 * take into account large objects (ToDo).
671 * -------------------------------------------------------------------------- */
674 calcAllocated( void )
682 /* All tasks must be stopped. Can't assert that all the
683 capabilities are owned by the scheduler, though: one or more
684 tasks might have been stopped while they were running (non-main)
686 /* ASSERT(n_free_capabilities == RtsFlags.ParFlags.nNodes); */
689 n_free_capabilities * RtsFlags.GcFlags.minAllocAreaSize * BLOCK_SIZE_W
692 for (cap = free_capabilities; cap != NULL; cap = cap->link) {
693 for ( bd = cap->r.rCurrentNursery->link; bd != NULL; bd = bd->link ) {
694 allocated -= BLOCK_SIZE_W;
696 if (cap->r.rCurrentNursery->free < cap->r.rCurrentNursery->start
698 allocated -= (cap->r.rCurrentNursery->start + BLOCK_SIZE_W)
699 - cap->r.rCurrentNursery->free;
704 bdescr *current_nursery = MainCapability.r.rCurrentNursery;
706 allocated = (g0s0->n_blocks * BLOCK_SIZE_W) + allocated_bytes();
707 for ( bd = current_nursery->link; bd != NULL; bd = bd->link ) {
708 allocated -= BLOCK_SIZE_W;
710 if (current_nursery->free < current_nursery->start + BLOCK_SIZE_W) {
711 allocated -= (current_nursery->start + BLOCK_SIZE_W)
712 - current_nursery->free;
716 total_allocated += allocated;
720 /* Approximate the amount of live data in the heap. To be called just
721 * after garbage collection (see GarbageCollect()).
730 if (RtsFlags.GcFlags.generations == 1) {
731 live = (g0s0->n_to_blocks - 1) * BLOCK_SIZE_W +
732 ((lnat)g0s0->hp_bd->free - (lnat)g0s0->hp_bd->start) / sizeof(W_);
736 for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
737 for (s = 0; s < generations[g].n_steps; s++) {
738 /* approximate amount of live data (doesn't take into account slop
739 * at end of each block).
741 if (g == 0 && s == 0) {
744 stp = &generations[g].steps[s];
745 live += (stp->n_large_blocks + stp->n_blocks - 1) * BLOCK_SIZE_W;
746 if (stp->hp_bd != NULL) {
747 live += ((lnat)stp->hp_bd->free - (lnat)stp->hp_bd->start)
755 /* Approximate the number of blocks that will be needed at the next
756 * garbage collection.
758 * Assume: all data currently live will remain live. Steps that will
759 * be collected next time will therefore need twice as many blocks
760 * since all the data will be copied.
769 for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
770 for (s = 0; s < generations[g].n_steps; s++) {
771 if (g == 0 && s == 0) { continue; }
772 stp = &generations[g].steps[s];
773 if (generations[g].steps[0].n_blocks +
774 generations[g].steps[0].n_large_blocks
775 > generations[g].max_blocks
776 && stp->is_compacted == 0) {
777 needed += 2 * stp->n_blocks;
779 needed += stp->n_blocks;
786 /* -----------------------------------------------------------------------------
789 memInventory() checks for memory leaks by counting up all the
790 blocks we know about and comparing that to the number of blocks
791 allegedly floating around in the system.
792 -------------------------------------------------------------------------- */
802 lnat total_blocks = 0, free_blocks = 0;
804 /* count the blocks we current have */
806 for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
807 for (s = 0; s < generations[g].n_steps; s++) {
808 stp = &generations[g].steps[s];
809 total_blocks += stp->n_blocks;
810 if (RtsFlags.GcFlags.generations == 1) {
811 /* two-space collector has a to-space too :-) */
812 total_blocks += g0s0->n_to_blocks;
814 for (bd = stp->large_objects; bd; bd = bd->link) {
815 total_blocks += bd->blocks;
816 /* hack for megablock groups: they have an extra block or two in
817 the second and subsequent megablocks where the block
818 descriptors would normally go.
820 if (bd->blocks > BLOCKS_PER_MBLOCK) {
821 total_blocks -= (MBLOCK_SIZE / BLOCK_SIZE - BLOCKS_PER_MBLOCK)
822 * (bd->blocks/(MBLOCK_SIZE/BLOCK_SIZE));
828 /* any blocks held by allocate() */
829 for (bd = small_alloc_list; bd; bd = bd->link) {
830 total_blocks += bd->blocks;
834 if (RtsFlags.ProfFlags.doHeapProfile == HEAP_BY_RETAINER) {
835 for (bd = firstStack; bd != NULL; bd = bd->link)
836 total_blocks += bd->blocks;
840 // count the blocks allocated by the arena allocator
841 total_blocks += arenaBlocks();
843 /* count the blocks on the free list */
844 free_blocks = countFreeList();
846 if (total_blocks + free_blocks != mblocks_allocated *
848 fprintf(stderr, "Blocks: %ld live + %ld free = %ld total (%ld around)\n",
849 total_blocks, free_blocks, total_blocks + free_blocks,
850 mblocks_allocated * BLOCKS_PER_MBLOCK);
853 ASSERT(total_blocks + free_blocks == mblocks_allocated * BLOCKS_PER_MBLOCK);
858 countBlocks(bdescr *bd)
861 for (n=0; bd != NULL; bd=bd->link) {
867 /* Full heap sanity check. */
873 if (RtsFlags.GcFlags.generations == 1) {
874 checkHeap(g0s0->to_blocks);
875 checkChain(g0s0->large_objects);
878 for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
879 for (s = 0; s < generations[g].n_steps; s++) {
880 ASSERT(countBlocks(generations[g].steps[s].blocks)
881 == generations[g].steps[s].n_blocks);
882 ASSERT(countBlocks(generations[g].steps[s].large_objects)
883 == generations[g].steps[s].n_large_blocks);
884 if (g == 0 && s == 0) { continue; }
885 checkHeap(generations[g].steps[s].blocks);
886 checkChain(generations[g].steps[s].large_objects);
888 checkMutableList(generations[g].mut_list, g);
889 checkMutOnceList(generations[g].mut_once_list, g);
893 checkFreeListSanity();
897 // handy function for use in gdb, because Bdescr() is inlined.
898 extern bdescr *_bdescr( StgPtr p );