1 /* -----------------------------------------------------------------------------
3 * (c) The GHC Team, 1998-2008
5 * Storage manager front end
7 * Documentation on the architecture of the Storage Manager can be
8 * found in the online commentary:
10 * http://hackage.haskell.org/trac/ghc/wiki/Commentary/Rts/Storage
12 * ---------------------------------------------------------------------------*/
14 #include "PosixSource.h"
20 #include "BlockAlloc.h"
24 #include "Capability.h"
26 #include "RetainerProfile.h" // for counting memory blocks (memInventory)
37 * All these globals require sm_mutex to access in THREADED_RTS mode.
39 StgClosure *caf_list = NULL;
40 StgClosure *revertible_caf_list = NULL;
43 nat alloc_blocks_lim; /* GC if n_large_blocks in any nursery
48 generation *generations = NULL; /* all the generations */
49 generation *g0 = NULL; /* generation 0, for convenience */
50 generation *oldest_gen = NULL; /* oldest generation, for convenience */
52 nursery *nurseries = NULL; /* array of nurseries, size == n_capabilities */
56 * Storage manager mutex: protects all the above state from
57 * simultaneous access by two STG threads.
62 static void allocNurseries ( void );
65 initGeneration (generation *gen, int g)
69 gen->par_collections = 0;
70 gen->failed_promotions = 0;
75 gen->live_estimate = 0;
76 gen->old_blocks = NULL;
77 gen->n_old_blocks = 0;
78 gen->large_objects = NULL;
79 gen->n_large_blocks = 0;
80 gen->n_new_large_blocks = 0;
81 gen->mut_list = allocBlock();
82 gen->scavenged_large_objects = NULL;
83 gen->n_scavenged_large_blocks = 0;
88 initSpinLock(&gen->sync_large_objects);
90 gen->threads = END_TSO_QUEUE;
91 gen->old_threads = END_TSO_QUEUE;
99 if (generations != NULL) {
100 // multi-init protection
106 /* Sanity check to make sure the LOOKS_LIKE_ macros appear to be
107 * doing something reasonable.
109 /* We use the NOT_NULL variant or gcc warns that the test is always true */
110 ASSERT(LOOKS_LIKE_INFO_PTR_NOT_NULL((StgWord)&stg_BLOCKING_QUEUE_CLEAN_info));
111 ASSERT(LOOKS_LIKE_CLOSURE_PTR(&stg_dummy_ret_closure));
112 ASSERT(!HEAP_ALLOCED(&stg_dummy_ret_closure));
114 if (RtsFlags.GcFlags.maxHeapSize != 0 &&
115 RtsFlags.GcFlags.heapSizeSuggestion >
116 RtsFlags.GcFlags.maxHeapSize) {
117 RtsFlags.GcFlags.maxHeapSize = RtsFlags.GcFlags.heapSizeSuggestion;
120 if (RtsFlags.GcFlags.maxHeapSize != 0 &&
121 RtsFlags.GcFlags.minAllocAreaSize >
122 RtsFlags.GcFlags.maxHeapSize) {
123 errorBelch("maximum heap size (-M) is smaller than minimum alloc area size (-A)");
124 RtsFlags.GcFlags.minAllocAreaSize = RtsFlags.GcFlags.maxHeapSize;
127 initBlockAllocator();
129 #if defined(THREADED_RTS)
130 initMutex(&sm_mutex);
135 /* allocate generation info array */
136 generations = (generation *)stgMallocBytes(RtsFlags.GcFlags.generations
137 * sizeof(struct generation_),
138 "initStorage: gens");
140 /* Initialise all generations */
141 for(g = 0; g < RtsFlags.GcFlags.generations; g++) {
142 initGeneration(&generations[g], g);
145 /* A couple of convenience pointers */
146 g0 = &generations[0];
147 oldest_gen = &generations[RtsFlags.GcFlags.generations-1];
149 nurseries = stgMallocBytes(n_capabilities * sizeof(struct nursery_),
150 "initStorage: nurseries");
152 /* Set up the destination pointers in each younger gen. step */
153 for (g = 0; g < RtsFlags.GcFlags.generations-1; g++) {
154 generations[g].to = &generations[g+1];
156 oldest_gen->to = oldest_gen;
158 /* The oldest generation has one step. */
159 if (RtsFlags.GcFlags.compact || RtsFlags.GcFlags.sweep) {
160 if (RtsFlags.GcFlags.generations == 1) {
161 errorBelch("WARNING: compact/sweep is incompatible with -G1; disabled");
163 oldest_gen->mark = 1;
164 if (RtsFlags.GcFlags.compact)
165 oldest_gen->compact = 1;
169 generations[0].max_blocks = 0;
171 /* The allocation area. Policy: keep the allocation area
172 * small to begin with, even if we have a large suggested heap
173 * size. Reason: we're going to do a major collection first, and we
174 * don't want it to be a big one. This vague idea is borne out by
175 * rigorous experimental evidence.
179 weak_ptr_list = NULL;
180 caf_list = END_OF_STATIC_LIST;
181 revertible_caf_list = END_OF_STATIC_LIST;
183 /* initialise the allocate() interface */
184 alloc_blocks_lim = RtsFlags.GcFlags.minAllocAreaSize;
189 initSpinLock(&gc_alloc_block_sync);
195 // allocate a block for each mut list
196 for (n = 0; n < n_capabilities; n++) {
197 for (g = 1; g < RtsFlags.GcFlags.generations; g++) {
198 capabilities[n].mut_lists[g] = allocBlock();
204 IF_DEBUG(gc, statDescribeGens());
212 stat_exit(calcAllocated());
216 freeStorage (rtsBool free_heap)
218 stgFree(generations);
219 if (free_heap) freeAllMBlocks();
220 #if defined(THREADED_RTS)
221 closeMutex(&sm_mutex);
227 /* -----------------------------------------------------------------------------
230 The entry code for every CAF does the following:
232 - builds a BLACKHOLE in the heap
233 - pushes an update frame pointing to the BLACKHOLE
234 - calls newCaf, below
235 - updates the CAF with a static indirection to the BLACKHOLE
237 Why do we build an BLACKHOLE in the heap rather than just updating
238 the thunk directly? It's so that we only need one kind of update
239 frame - otherwise we'd need a static version of the update frame too.
241 newCaf() does the following:
243 - it puts the CAF on the oldest generation's mutable list.
244 This is so that we treat the CAF as a root when collecting
247 For GHCI, we have additional requirements when dealing with CAFs:
249 - we must *retain* all dynamically-loaded CAFs ever entered,
250 just in case we need them again.
251 - we must be able to *revert* CAFs that have been evaluated, to
252 their pre-evaluated form.
254 To do this, we use an additional CAF list. When newCaf() is
255 called on a dynamically-loaded CAF, we add it to the CAF list
256 instead of the old-generation mutable list, and save away its
257 old info pointer (in caf->saved_info) for later reversion.
259 To revert all the CAFs, we traverse the CAF list and reset the
260 info pointer to caf->saved_info, then throw away the CAF list.
261 (see GC.c:revertCAFs()).
265 -------------------------------------------------------------------------- */
268 newCAF(StgRegTable *reg, StgClosure* caf)
273 // If we are in GHCi _and_ we are using dynamic libraries,
274 // then we can't redirect newCAF calls to newDynCAF (see below),
275 // so we make newCAF behave almost like newDynCAF.
276 // The dynamic libraries might be used by both the interpreted
277 // program and GHCi itself, so they must not be reverted.
278 // This also means that in GHCi with dynamic libraries, CAFs are not
279 // garbage collected. If this turns out to be a problem, we could
280 // do another hack here and do an address range test on caf to figure
281 // out whether it is from a dynamic library.
282 ((StgIndStatic *)caf)->saved_info = (StgInfoTable *)caf->header.info;
284 ACQUIRE_SM_LOCK; // caf_list is global, locked by sm_mutex
285 ((StgIndStatic *)caf)->static_link = caf_list;
291 // Put this CAF on the mutable list for the old generation.
292 ((StgIndStatic *)caf)->saved_info = NULL;
293 if (oldest_gen->no != 0) {
294 recordMutableCap(caf, regTableToCapability(reg), oldest_gen->no);
299 // External API for setting the keepCAFs flag. see #3900.
306 // An alternate version of newCaf which is used for dynamically loaded
307 // object code in GHCi. In this case we want to retain *all* CAFs in
308 // the object code, because they might be demanded at any time from an
309 // expression evaluated on the command line.
310 // Also, GHCi might want to revert CAFs, so we add these to the
311 // revertible_caf_list.
313 // The linker hackily arranges that references to newCaf from dynamic
314 // code end up pointing to newDynCAF.
316 newDynCAF (StgRegTable *reg STG_UNUSED, StgClosure *caf)
320 ((StgIndStatic *)caf)->saved_info = (StgInfoTable *)caf->header.info;
321 ((StgIndStatic *)caf)->static_link = revertible_caf_list;
322 revertible_caf_list = caf;
327 /* -----------------------------------------------------------------------------
329 -------------------------------------------------------------------------- */
332 allocNursery (bdescr *tail, nat blocks)
337 // We allocate the nursery as a single contiguous block and then
338 // divide it into single blocks manually. This way we guarantee
339 // that the nursery blocks are adjacent, so that the processor's
340 // automatic prefetching works across nursery blocks. This is a
341 // tiny optimisation (~0.5%), but it's free.
344 n = stg_min(blocks, BLOCKS_PER_MBLOCK);
348 for (i = 0; i < n; i++) {
349 initBdescr(&bd[i], g0, g0);
355 bd[i].u.back = &bd[i-1];
361 bd[i].link = &bd[i+1];
365 tail->u.back = &bd[i];
369 bd[i].free = bd[i].start;
379 assignNurseriesToCapabilities (void)
383 for (i = 0; i < n_capabilities; i++) {
384 capabilities[i].r.rNursery = &nurseries[i];
385 capabilities[i].r.rCurrentNursery = nurseries[i].blocks;
386 capabilities[i].r.rCurrentAlloc = NULL;
391 allocNurseries( void )
395 for (i = 0; i < n_capabilities; i++) {
396 nurseries[i].blocks =
397 allocNursery(NULL, RtsFlags.GcFlags.minAllocAreaSize);
398 nurseries[i].n_blocks =
399 RtsFlags.GcFlags.minAllocAreaSize;
401 assignNurseriesToCapabilities();
405 resetNurseries( void )
410 for (i = 0; i < n_capabilities; i++) {
411 for (bd = nurseries[i].blocks; bd; bd = bd->link) {
412 bd->free = bd->start;
413 ASSERT(bd->gen_no == 0);
414 ASSERT(bd->gen == g0);
415 IF_DEBUG(sanity,memset(bd->start, 0xaa, BLOCK_SIZE));
418 assignNurseriesToCapabilities();
422 countNurseryBlocks (void)
427 for (i = 0; i < n_capabilities; i++) {
428 blocks += nurseries[i].n_blocks;
434 resizeNursery ( nursery *nursery, nat blocks )
439 nursery_blocks = nursery->n_blocks;
440 if (nursery_blocks == blocks) return;
442 if (nursery_blocks < blocks) {
443 debugTrace(DEBUG_gc, "increasing size of nursery to %d blocks",
445 nursery->blocks = allocNursery(nursery->blocks, blocks-nursery_blocks);
450 debugTrace(DEBUG_gc, "decreasing size of nursery to %d blocks",
453 bd = nursery->blocks;
454 while (nursery_blocks > blocks) {
456 next_bd->u.back = NULL;
457 nursery_blocks -= bd->blocks; // might be a large block
461 nursery->blocks = bd;
462 // might have gone just under, by freeing a large block, so make
463 // up the difference.
464 if (nursery_blocks < blocks) {
465 nursery->blocks = allocNursery(nursery->blocks, blocks-nursery_blocks);
469 nursery->n_blocks = blocks;
470 ASSERT(countBlocks(nursery->blocks) == nursery->n_blocks);
474 // Resize each of the nurseries to the specified size.
477 resizeNurseriesFixed (nat blocks)
480 for (i = 0; i < n_capabilities; i++) {
481 resizeNursery(&nurseries[i], blocks);
486 // Resize the nurseries to the total specified size.
489 resizeNurseries (nat blocks)
491 // If there are multiple nurseries, then we just divide the number
492 // of available blocks between them.
493 resizeNurseriesFixed(blocks / n_capabilities);
497 /* -----------------------------------------------------------------------------
498 move_STACK is called to update the TSO structure after it has been
499 moved from one place to another.
500 -------------------------------------------------------------------------- */
503 move_STACK (StgStack *src, StgStack *dest)
507 // relocate the stack pointer...
508 diff = (StgPtr)dest - (StgPtr)src; // In *words*
509 dest->sp = (StgPtr)dest->sp + diff;
512 /* -----------------------------------------------------------------------------
515 This allocates memory in the current thread - it is intended for
516 use primarily from STG-land where we have a Capability. It is
517 better than allocate() because it doesn't require taking the
518 sm_mutex lock in the common case.
520 Memory is allocated directly from the nursery if possible (but not
521 from the current nursery block, so as not to interfere with
523 -------------------------------------------------------------------------- */
526 allocate (Capability *cap, lnat n)
531 if (n >= LARGE_OBJECT_THRESHOLD/sizeof(W_)) {
532 lnat req_blocks = (lnat)BLOCK_ROUND_UP(n*sizeof(W_)) / BLOCK_SIZE;
534 // Attempting to allocate an object larger than maxHeapSize
535 // should definitely be disallowed. (bug #1791)
536 if (RtsFlags.GcFlags.maxHeapSize > 0 &&
537 req_blocks >= RtsFlags.GcFlags.maxHeapSize) {
539 // heapOverflow() doesn't exit (see #2592), but we aren't
540 // in a position to do a clean shutdown here: we
541 // either have to allocate the memory or exit now.
542 // Allocating the memory would be bad, because the user
543 // has requested that we not exceed maxHeapSize, so we
545 stg_exit(EXIT_HEAPOVERFLOW);
549 bd = allocGroup(req_blocks);
550 dbl_link_onto(bd, &g0->large_objects);
551 g0->n_large_blocks += bd->blocks; // might be larger than req_blocks
552 g0->n_new_large_blocks += bd->blocks;
554 initBdescr(bd, g0, g0);
555 bd->flags = BF_LARGE;
556 bd->free = bd->start + n;
560 /* small allocation (<LARGE_OBJECT_THRESHOLD) */
562 TICK_ALLOC_HEAP_NOCTR(n);
565 bd = cap->r.rCurrentAlloc;
566 if (bd == NULL || bd->free + n > bd->start + BLOCK_SIZE_W) {
568 // The CurrentAlloc block is full, we need to find another
569 // one. First, we try taking the next block from the
571 bd = cap->r.rCurrentNursery->link;
573 if (bd == NULL || bd->free + n > bd->start + BLOCK_SIZE_W) {
574 // The nursery is empty, or the next block is already
575 // full: allocate a fresh block (we can't fail here).
578 cap->r.rNursery->n_blocks++;
580 initBdescr(bd, g0, g0);
582 // If we had to allocate a new block, then we'll GC
583 // pretty quickly now, because MAYBE_GC() will
584 // notice that CurrentNursery->link is NULL.
586 // we have a block in the nursery: take it and put
587 // it at the *front* of the nursery list, and use it
588 // to allocate() from.
589 cap->r.rCurrentNursery->link = bd->link;
590 if (bd->link != NULL) {
591 bd->link->u.back = cap->r.rCurrentNursery;
594 dbl_link_onto(bd, &cap->r.rNursery->blocks);
595 cap->r.rCurrentAlloc = bd;
596 IF_DEBUG(sanity, checkNurserySanity(cap->r.rNursery));
601 IF_DEBUG(sanity, ASSERT(*((StgWord8*)p) == 0xaa));
605 /* ---------------------------------------------------------------------------
606 Allocate a fixed/pinned object.
608 We allocate small pinned objects into a single block, allocating a
609 new block when the current one overflows. The block is chained
610 onto the large_object_list of generation 0.
612 NOTE: The GC can't in general handle pinned objects. This
613 interface is only safe to use for ByteArrays, which have no
614 pointers and don't require scavenging. It works because the
615 block's descriptor has the BF_LARGE flag set, so the block is
616 treated as a large object and chained onto various lists, rather
617 than the individual objects being copied. However, when it comes
618 to scavenge the block, the GC will only scavenge the first object.
619 The reason is that the GC can't linearly scan a block of pinned
620 objects at the moment (doing so would require using the
621 mostly-copying techniques). But since we're restricting ourselves
622 to pinned ByteArrays, not scavenging is ok.
624 This function is called by newPinnedByteArray# which immediately
625 fills the allocated memory with a MutableByteArray#.
626 ------------------------------------------------------------------------- */
629 allocatePinned (Capability *cap, lnat n)
634 // If the request is for a large object, then allocate()
635 // will give us a pinned object anyway.
636 if (n >= LARGE_OBJECT_THRESHOLD/sizeof(W_)) {
637 p = allocate(cap, n);
638 Bdescr(p)->flags |= BF_PINNED;
642 TICK_ALLOC_HEAP_NOCTR(n);
645 bd = cap->pinned_object_block;
647 // If we don't have a block of pinned objects yet, or the current
648 // one isn't large enough to hold the new object, allocate a new one.
649 if (bd == NULL || (bd->free + n) > (bd->start + BLOCK_SIZE_W)) {
651 cap->pinned_object_block = bd = allocBlock();
652 dbl_link_onto(bd, &g0->large_objects);
653 g0->n_large_blocks++;
654 g0->n_new_large_blocks++;
656 initBdescr(bd, g0, g0);
657 bd->flags = BF_PINNED | BF_LARGE;
658 bd->free = bd->start;
666 /* -----------------------------------------------------------------------------
668 -------------------------------------------------------------------------- */
671 This is the write barrier for MUT_VARs, a.k.a. IORefs. A
672 MUT_VAR_CLEAN object is not on the mutable list; a MUT_VAR_DIRTY
673 is. When written to, a MUT_VAR_CLEAN turns into a MUT_VAR_DIRTY
674 and is put on the mutable list.
677 dirty_MUT_VAR(StgRegTable *reg, StgClosure *p)
679 Capability *cap = regTableToCapability(reg);
680 if (p->header.info == &stg_MUT_VAR_CLEAN_info) {
681 p->header.info = &stg_MUT_VAR_DIRTY_info;
682 recordClosureMutated(cap,p);
686 // Setting a TSO's link field with a write barrier.
687 // It is *not* necessary to call this function when
688 // * setting the link field to END_TSO_QUEUE
689 // * putting a TSO on the blackhole_queue
690 // * setting the link field of the currently running TSO, as it
691 // will already be dirty.
693 setTSOLink (Capability *cap, StgTSO *tso, StgTSO *target)
695 if (tso->dirty == 0) {
697 recordClosureMutated(cap,(StgClosure*)tso);
703 setTSOPrev (Capability *cap, StgTSO *tso, StgTSO *target)
705 if (tso->dirty == 0) {
707 recordClosureMutated(cap,(StgClosure*)tso);
709 tso->block_info.prev = target;
713 dirty_TSO (Capability *cap, StgTSO *tso)
715 if (tso->dirty == 0) {
717 recordClosureMutated(cap,(StgClosure*)tso);
722 dirty_STACK (Capability *cap, StgStack *stack)
724 if (stack->dirty == 0) {
726 recordClosureMutated(cap,(StgClosure*)stack);
731 This is the write barrier for MVARs. An MVAR_CLEAN objects is not
732 on the mutable list; a MVAR_DIRTY is. When written to, a
733 MVAR_CLEAN turns into a MVAR_DIRTY and is put on the mutable list.
734 The check for MVAR_CLEAN is inlined at the call site for speed,
735 this really does make a difference on concurrency-heavy benchmarks
736 such as Chaneneos and cheap-concurrency.
739 dirty_MVAR(StgRegTable *reg, StgClosure *p)
741 recordClosureMutated(regTableToCapability(reg),p);
744 /* -----------------------------------------------------------------------------
746 * -------------------------------------------------------------------------- */
748 /* -----------------------------------------------------------------------------
751 * Approximate how much we've allocated: number of blocks in the
752 * nursery + blocks allocated via allocate() - unused nusery blocks.
753 * This leaves a little slop at the end of each block.
754 * -------------------------------------------------------------------------- */
757 calcAllocated( void )
763 allocated = countNurseryBlocks() * BLOCK_SIZE_W;
765 for (i = 0; i < n_capabilities; i++) {
767 for ( bd = capabilities[i].r.rCurrentNursery->link;
768 bd != NULL; bd = bd->link ) {
769 allocated -= BLOCK_SIZE_W;
771 cap = &capabilities[i];
772 if (cap->r.rCurrentNursery->free <
773 cap->r.rCurrentNursery->start + BLOCK_SIZE_W) {
774 allocated -= (cap->r.rCurrentNursery->start + BLOCK_SIZE_W)
775 - cap->r.rCurrentNursery->free;
777 if (cap->pinned_object_block != NULL) {
778 allocated -= (cap->pinned_object_block->start + BLOCK_SIZE_W) -
779 cap->pinned_object_block->free;
783 allocated += g0->n_new_large_blocks * BLOCK_SIZE_W;
788 /* Approximate the amount of live data in the heap. To be called just
789 * after garbage collection (see GarbageCollect()).
791 lnat calcLiveBlocks (void)
797 for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
798 /* approximate amount of live data (doesn't take into account slop
799 * at end of each block).
801 gen = &generations[g];
802 live += gen->n_large_blocks + gen->n_blocks;
807 lnat countOccupied (bdescr *bd)
812 for (; bd != NULL; bd = bd->link) {
813 ASSERT(bd->free <= bd->start + bd->blocks * BLOCK_SIZE_W);
814 words += bd->free - bd->start;
819 // Return an accurate count of the live data in the heap, excluding
821 lnat calcLiveWords (void)
828 for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
829 gen = &generations[g];
830 live += gen->n_words + countOccupied(gen->large_objects);
835 /* Approximate the number of blocks that will be needed at the next
836 * garbage collection.
838 * Assume: all data currently live will remain live. Generationss
839 * that will be collected next time will therefore need twice as many
840 * blocks since all the data will be copied.
849 for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
850 gen = &generations[g];
852 // we need at least this much space
853 needed += gen->n_blocks + gen->n_large_blocks;
855 // any additional space needed to collect this gen next time?
856 if (g == 0 || // always collect gen 0
857 (gen->n_blocks + gen->n_large_blocks > gen->max_blocks)) {
858 // we will collect this gen next time
861 needed += gen->n_blocks / BITS_IN(W_);
863 needed += gen->n_blocks / 100;
866 continue; // no additional space needed for compaction
868 needed += gen->n_blocks;
875 /* ----------------------------------------------------------------------------
878 Executable memory must be managed separately from non-executable
879 memory. Most OSs these days require you to jump through hoops to
880 dynamically allocate executable memory, due to various security
883 Here we provide a small memory allocator for executable memory.
884 Memory is managed with a page granularity; we allocate linearly
885 in the page, and when the page is emptied (all objects on the page
886 are free) we free the page again, not forgetting to make it
889 TODO: The inability to handle objects bigger than BLOCK_SIZE_W means that
890 the linker cannot use allocateExec for loading object code files
891 on Windows. Once allocateExec can handle larger objects, the linker
892 should be modified to use allocateExec instead of VirtualAlloc.
893 ------------------------------------------------------------------------- */
895 #if defined(linux_HOST_OS)
897 // On Linux we need to use libffi for allocating executable memory,
898 // because it knows how to work around the restrictions put in place
901 void *allocateExec (nat bytes, void **exec_ret)
905 ret = ffi_closure_alloc (sizeof(void *) + (size_t)bytes, (void**)&exec);
907 if (ret == NULL) return ret;
908 *ret = ret; // save the address of the writable mapping, for freeExec().
909 *exec_ret = exec + 1;
913 // freeExec gets passed the executable address, not the writable address.
914 void freeExec (void *addr)
917 writable = *((void**)addr - 1);
919 ffi_closure_free (writable);
925 void *allocateExec (nat bytes, void **exec_ret)
932 // round up to words.
933 n = (bytes + sizeof(W_) + 1) / sizeof(W_);
935 if (n+1 > BLOCK_SIZE_W) {
936 barf("allocateExec: can't handle large objects");
939 if (exec_block == NULL ||
940 exec_block->free + n + 1 > exec_block->start + BLOCK_SIZE_W) {
942 lnat pagesize = getPageSize();
943 bd = allocGroup(stg_max(1, pagesize / BLOCK_SIZE));
944 debugTrace(DEBUG_gc, "allocate exec block %p", bd->start);
947 bd->link = exec_block;
948 if (exec_block != NULL) {
949 exec_block->u.back = bd;
952 setExecutable(bd->start, bd->blocks * BLOCK_SIZE, rtsTrue);
955 *(exec_block->free) = n; // store the size of this chunk
956 exec_block->gen_no += n; // gen_no stores the number of words allocated
957 ret = exec_block->free + 1;
958 exec_block->free += n + 1;
965 void freeExec (void *addr)
967 StgPtr p = (StgPtr)addr - 1;
968 bdescr *bd = Bdescr((StgPtr)p);
970 if ((bd->flags & BF_EXEC) == 0) {
971 barf("freeExec: not executable");
974 if (*(StgPtr)p == 0) {
975 barf("freeExec: already free?");
980 bd->gen_no -= *(StgPtr)p;
983 if (bd->gen_no == 0) {
984 // Free the block if it is empty, but not if it is the block at
985 // the head of the queue.
986 if (bd != exec_block) {
987 debugTrace(DEBUG_gc, "free exec block %p", bd->start);
988 dbl_link_remove(bd, &exec_block);
989 setExecutable(bd->start, bd->blocks * BLOCK_SIZE, rtsFalse);
992 bd->free = bd->start;
999 #endif /* mingw32_HOST_OS */
1003 // handy function for use in gdb, because Bdescr() is inlined.
1004 extern bdescr *_bdescr( StgPtr p );