/* Used to avoid long recursion due to selector thunks
*/
-lnat thunk_selector_depth = 0;
#define MAX_THUNK_SELECTOR_DEPTH 16
-static StgClosure * eval_thunk_selector (StgSelector * p, rtsBool);
+static void eval_thunk_selector (StgClosure **q, StgSelector * p, rtsBool);
+STATIC_INLINE void evacuate_large(StgPtr p);
-STATIC_INLINE void
-upd_evacuee(StgClosure *p, StgClosure *dest)
-{
- // not true: (ToDo: perhaps it should be)
- // ASSERT(Bdescr((P_)dest)->flags & BF_EVACUATED);
- SET_INFO(p, &stg_EVACUATED_info);
- ((StgEvacuated *)p)->evacuee = dest;
-}
-
-
-STATIC_INLINE StgClosure *
-copy_tag(StgClosure *src, nat size, step *stp,StgWord tag)
-{
- StgPtr to, from;
- nat i;
-#ifdef PROFILING
- // @LDV profiling
- nat size_org = size;
-#endif
-
- TICK_GC_WORDS_COPIED(size);
- /* Find out where we're going, using the handy "to" pointer in
- * the step of the source object. If it turns out we need to
- * evacuate to an older generation, adjust it here (see comment
- * by evacuate()).
- */
- if (stp->gen_no < evac_gen) {
- if (eager_promotion) {
- stp = &generations[evac_gen].steps[0];
- } else {
- failed_to_evac = rtsTrue;
- }
- }
-
- /* chain a new block onto the to-space for the destination step if
- * necessary.
- */
- if (stp->hp + size >= stp->hpLim) {
- gc_alloc_block(stp);
- }
-
- to = stp->hp;
- from = (StgPtr)src;
- stp->hp = to + size;
- for (i = 0; i < size; i++) { // unroll for small i
- to[i] = from[i];
- }
-
- /* retag pointer before updating EVACUATE closure and returning */
- to = (StgPtr)TAG_CLOSURE(tag,(StgClosure*)to);
-
- upd_evacuee((StgClosure *)from,(StgClosure *)to);
-
-#ifdef PROFILING
- // We store the size of the just evacuated object in the LDV word so that
- // the profiler can guess the position of the next object later.
- SET_EVACUAEE_FOR_LDV(from, size_org);
-#endif
- return (StgClosure *)to;
-}
+/* -----------------------------------------------------------------------------
+ Allocate some space in which to copy an object.
+ -------------------------------------------------------------------------- */
-// Same as copy() above, except the object will be allocated in memory
-// that will not be scavenged. Used for object that have no pointer
-// fields.
-STATIC_INLINE StgClosure *
-copy_noscav_tag(StgClosure *src, nat size, step *stp, StgWord tag)
+STATIC_INLINE StgPtr
+alloc_for_copy (nat size, step *stp)
{
- StgPtr to, from;
- nat i;
-#ifdef PROFILING
- // @LDV profiling
- nat size_org = size;
-#endif
-
- TICK_GC_WORDS_COPIED(size);
- /* Find out where we're going, using the handy "to" pointer in
- * the step of the source object. If it turns out we need to
- * evacuate to an older generation, adjust it here (see comment
- * by evacuate()).
- */
- if (stp->gen_no < evac_gen) {
- if (eager_promotion) {
- stp = &generations[evac_gen].steps[0];
- } else {
- failed_to_evac = rtsTrue;
- }
- }
-
- /* chain a new block onto the to-space for the destination step if
- * necessary.
- */
- if (stp->scavd_hp + size >= stp->scavd_hpLim) {
- gc_alloc_scavd_block(stp);
- }
-
- to = stp->scavd_hp;
- from = (StgPtr)src;
- stp->scavd_hp = to + size;
- for (i = 0; i < size; i++) { // unroll for small i
- to[i] = from[i];
- }
-
- /* retag pointer before updating EVACUATE closure and returning */
- to = (StgPtr)TAG_CLOSURE(tag,(StgClosure*)to);
+ StgPtr to;
+ step_workspace *ws;
+ bdescr *bd;
- upd_evacuee((StgClosure *)from,(StgClosure *)to);
+ /* Find out where we're going, using the handy "to" pointer in
+ * the step of the source object. If it turns out we need to
+ * evacuate to an older generation, adjust it here (see comment
+ * by evacuate()).
+ */
+ if (stp < gct->evac_step) {
+ if (gct->eager_promotion) {
+ stp = gct->evac_step;
+ } else {
+ gct->failed_to_evac = rtsTrue;
+ }
+ }
+
+ ws = &gct->steps[stp->gen_no][stp->no];
+
+ /* chain a new block onto the to-space for the destination step if
+ * necessary.
+ */
+ bd = ws->todo_bd;
+ to = bd->free;
+ if (to + size >= bd->start + BLOCK_SIZE_W) {
+ bd = gc_alloc_todo_block(ws);
+ to = bd->free;
+ }
+ bd->free = to + size;
-#ifdef PROFILING
- // We store the size of the just evacuated object in the LDV word so that
- // the profiler can guess the position of the next object later.
- SET_EVACUAEE_FOR_LDV(from, size_org);
-#endif
- return (StgClosure *)to;
+ return to;
}
-
-/* Special version of copy() for when we only want to copy the info
- * pointer of an object, but reserve some padding after it. This is
- * used to optimise evacuation of BLACKHOLEs.
- */
-
-
-static StgClosure *
-copyPart(StgClosure *src, nat size_to_reserve, nat size_to_copy, step *stp)
-{
- P_ dest, to, from;
-#ifdef PROFILING
- // @LDV profiling
- nat size_to_copy_org = size_to_copy;
-#endif
-
- TICK_GC_WORDS_COPIED(size_to_copy);
- if (stp->gen_no < evac_gen) {
- if (eager_promotion) {
- stp = &generations[evac_gen].steps[0];
- } else {
- failed_to_evac = rtsTrue;
- }
- }
-
- if (stp->hp + size_to_reserve >= stp->hpLim) {
- gc_alloc_block(stp);
- }
-
- for(to = stp->hp, from = (P_)src; size_to_copy>0; --size_to_copy) {
- *to++ = *from++;
- }
- dest = stp->hp;
- stp->hp += size_to_reserve;
- upd_evacuee(src,(StgClosure *)dest);
-#ifdef PROFILING
- // We store the size of the just evacuated object in the LDV word so that
- // the profiler can guess the position of the next object later.
- // size_to_copy_org is wrong because the closure already occupies size_to_reserve
- // words.
- SET_EVACUAEE_FOR_LDV(src, size_to_reserve);
- // fill the slop
- if (size_to_reserve - size_to_copy_org > 0)
- LDV_FILL_SLOP(stp->hp - 1, (int)(size_to_reserve - size_to_copy_org));
-#endif
- return (StgClosure *)dest;
-}
-
+/* -----------------------------------------------------------------------------
+ The evacuate() code
+ -------------------------------------------------------------------------- */
-/* Copy wrappers that don't tag the closure after copying */
-STATIC_INLINE StgClosure *
-copy(StgClosure *src, nat size, step *stp)
-{
- return copy_tag(src,size,stp,0);
-}
+#define MINOR_GC
+#include "Evac.c-inc"
-STATIC_INLINE StgClosure *
-copy_noscav(StgClosure *src, nat size, step *stp)
-{
- return copy_noscav_tag(src,size,stp,0);
-}
+#undef MINOR_GC
+#include "Evac.c-inc"
/* -----------------------------------------------------------------------------
Evacuate a large object
that has been evacuated, or unset otherwise.
-------------------------------------------------------------------------- */
-
STATIC_INLINE void
evacuate_large(StgPtr p)
{
bdescr *bd = Bdescr(p);
step *stp;
+ step_workspace *ws;
// object must be at the beginning of the block (or be a ByteArray)
ASSERT(get_itbl((StgClosure *)p)->type == ARR_WORDS ||
// already evacuated?
if (bd->flags & BF_EVACUATED) {
- /* Don't forget to set the failed_to_evac flag if we didn't get
+ /* Don't forget to set the gct->failed_to_evac flag if we didn't get
* the desired destination (see comments in evacuate()).
*/
- if (bd->gen_no < evac_gen) {
- failed_to_evac = rtsTrue;
+ if (bd->step < gct->evac_step) {
+ gct->failed_to_evac = rtsTrue;
TICK_GC_FAILED_PROMOTION();
}
return;
}
stp = bd->step;
+
+ ACQUIRE_SPIN_LOCK(&stp->sync_large_objects);
// remove from large_object list
if (bd->u.back) {
bd->u.back->link = bd->link;
if (bd->link) {
bd->link->u.back = bd->u.back;
}
+ RELEASE_SPIN_LOCK(&stp->sync_large_objects);
/* link it on to the evacuated large object list of the destination step
*/
stp = bd->step->to;
- if (stp->gen_no < evac_gen) {
- if (eager_promotion) {
- stp = &generations[evac_gen].steps[0];
+ if (stp < gct->evac_step) {
+ if (gct->eager_promotion) {
+ stp = gct->evac_step;
} else {
- failed_to_evac = rtsTrue;
+ gct->failed_to_evac = rtsTrue;
}
}
+ ws = &gct->steps[stp->gen_no][stp->no];
bd->step = stp;
bd->gen_no = stp->gen_no;
- bd->link = stp->new_large_objects;
- stp->new_large_objects = bd;
+ bd->link = ws->todo_large_objects;
+ ws->todo_large_objects = bd;
bd->flags |= BF_EVACUATED;
}
/* -----------------------------------------------------------------------------
- Evacuate
-
- This is called (eventually) for every live object in the system.
-
- The caller to evacuate specifies a desired generation in the
- evac_gen global variable. The following conditions apply to
- evacuating an object which resides in generation M when we're
- collecting up to generation N
-
- if M >= evac_gen
- if M > N do nothing
- else evac to step->to
-
- if M < evac_gen evac to evac_gen, step 0
-
- if the object is already evacuated, then we check which generation
- it now resides in.
-
- if M >= evac_gen do nothing
- if M < evac_gen set failed_to_evac flag to indicate that we
- didn't manage to evacuate this object into evac_gen.
-
-
- OPTIMISATION NOTES:
+ Evaluate a THUNK_SELECTOR if possible.
- evacuate() is the single most important function performance-wise
- in the GC. Various things have been tried to speed it up, but as
- far as I can tell the code generated by gcc 3.2 with -O2 is about
- as good as it's going to get. We pass the argument to evacuate()
- in a register using the 'regparm' attribute (see the prototype for
- evacuate() near the top of this file).
+ p points to a THUNK_SELECTOR that we want to evaluate. The
+ result of "evaluating" it will be evacuated and a pointer to the
+ to-space closure will be returned.
- Changing evacuate() to take an (StgClosure **) rather than
- returning the new pointer seems attractive, because we can avoid
- writing back the pointer when it hasn't changed (eg. for a static
- object, or an object in a generation > N). However, I tried it and
- it doesn't help. One reason is that the (StgClosure **) pointer
- gets spilled to the stack inside evacuate(), resulting in far more
- extra reads/writes than we save.
+ If the THUNK_SELECTOR could not be evaluated (its selectee is still
+ a THUNK, for example), then the THUNK_SELECTOR itself will be
+ evacuated.
-------------------------------------------------------------------------- */
-
-REGPARM1 StgClosure *
-evacuate(StgClosure *q)
-{
- bdescr *bd = NULL;
- step *stp;
- const StgInfoTable *info;
- StgWord tag;
-
-loop:
- /* The tag and the pointer are split, to be merged after evacing */
- tag = GET_CLOSURE_TAG(q);
- q = UNTAG_CLOSURE(q);
-
- ASSERT(LOOKS_LIKE_CLOSURE_PTR(q));
-
- if (!HEAP_ALLOCED(q)) {
-
- if (!major_gc) return TAG_CLOSURE(tag,q);
-
- info = get_itbl(q);
- switch (info->type) {
-
- case THUNK_STATIC:
- if (info->srt_bitmap != 0 &&
- *THUNK_STATIC_LINK((StgClosure *)q) == NULL) {
- *THUNK_STATIC_LINK((StgClosure *)q) = static_objects;
- static_objects = (StgClosure *)q;
- }
- return q;
-
- case FUN_STATIC:
- if (info->srt_bitmap != 0 &&
- *FUN_STATIC_LINK((StgClosure *)q) == NULL) {
- *FUN_STATIC_LINK((StgClosure *)q) = static_objects;
- static_objects = (StgClosure *)q;
- }
- return q;
-
- case IND_STATIC:
- /* If q->saved_info != NULL, then it's a revertible CAF - it'll be
- * on the CAF list, so don't do anything with it here (we'll
- * scavenge it later).
- */
- if (((StgIndStatic *)q)->saved_info == NULL
- && *IND_STATIC_LINK((StgClosure *)q) == NULL) {
- *IND_STATIC_LINK((StgClosure *)q) = static_objects;
- static_objects = (StgClosure *)q;
- }
- return q;
-
- case CONSTR_STATIC:
- if (*STATIC_LINK(info,(StgClosure *)q) == NULL) {
- *STATIC_LINK(info,(StgClosure *)q) = static_objects;
- static_objects = (StgClosure *)q;
- /* I am assuming that static_objects pointers are not
- * written to other objects, and thus, no need to retag. */
- }
- return TAG_CLOSURE(tag,q);
-
- case CONSTR_NOCAF_STATIC:
- /* no need to put these on the static linked list, they don't need
- * to be scavenged.
- */
- return TAG_CLOSURE(tag,q);
-
- default:
- barf("evacuate(static): strange closure type %d", (int)(info->type));
- }
- }
-
- bd = Bdescr((P_)q);
-
- if (bd->gen_no > N) {
- /* Can't evacuate this object, because it's in a generation
- * older than the ones we're collecting. Let's hope that it's
- * in evac_gen or older, or we will have to arrange to track
- * this pointer using the mutable list.
- */
- if (bd->gen_no < evac_gen) {
- // nope
- failed_to_evac = rtsTrue;
- TICK_GC_FAILED_PROMOTION();
- }
- return TAG_CLOSURE(tag,q);
- }
-
- if ((bd->flags & (BF_LARGE | BF_COMPACTED | BF_EVACUATED)) != 0) {
-
- /* pointer into to-space: just return it. This normally
- * shouldn't happen, but alllowing it makes certain things
- * slightly easier (eg. the mutable list can contain the same
- * object twice, for example).
- */
- if (bd->flags & BF_EVACUATED) {
- if (bd->gen_no < evac_gen) {
- failed_to_evac = rtsTrue;
- TICK_GC_FAILED_PROMOTION();
- }
- return TAG_CLOSURE(tag,q);
- }
-
- /* evacuate large objects by re-linking them onto a different list.
- */
- if (bd->flags & BF_LARGE) {
- info = get_itbl(q);
- if (info->type == TSO &&
- ((StgTSO *)q)->what_next == ThreadRelocated) {
- q = (StgClosure *)((StgTSO *)q)->link;
- goto loop;
- }
- evacuate_large((P_)q);
- return TAG_CLOSURE(tag,q);
- }
-
- /* If the object is in a step that we're compacting, then we
- * need to use an alternative evacuate procedure.
- */
- if (bd->flags & BF_COMPACTED) {
- if (!is_marked((P_)q,bd)) {
- mark((P_)q,bd);
- if (mark_stack_full()) {
- mark_stack_overflowed = rtsTrue;
- reset_mark_stack();
- }
- push_mark_stack((P_)q);
- }
- return TAG_CLOSURE(tag,q);
- }
- }
-
- stp = bd->step->to;
-
- info = get_itbl(q);
-
- switch (info->type) {
-
- case MUT_VAR_CLEAN:
- case MUT_VAR_DIRTY:
- case MVAR_CLEAN:
- case MVAR_DIRTY:
- return copy(q,sizeW_fromITBL(info),stp);
-
- case CONSTR_0_1:
- {
- StgWord w = (StgWord)q->payload[0];
- if (q->header.info == Czh_con_info &&
- // unsigned, so always true: (StgChar)w >= MIN_CHARLIKE &&
- (StgChar)w <= MAX_CHARLIKE) {
- return TAG_CLOSURE(tag,
- (StgClosure *)CHARLIKE_CLOSURE((StgChar)w)
- );
- }
- if (q->header.info == Izh_con_info &&
- (StgInt)w >= MIN_INTLIKE && (StgInt)w <= MAX_INTLIKE) {
- return TAG_CLOSURE(tag,
- (StgClosure *)INTLIKE_CLOSURE((StgInt)w)
- );
- }
- // else
- return copy_noscav_tag(q,sizeofW(StgHeader)+1,stp,tag);
- }
-
- case FUN_0_1:
- case FUN_1_0:
- case CONSTR_1_0:
- return copy_tag(q,sizeofW(StgHeader)+1,stp,tag);
-
- case THUNK_1_0:
- case THUNK_0_1:
- return copy(q,sizeofW(StgThunk)+1,stp);
-
- case THUNK_1_1:
- case THUNK_2_0:
- case THUNK_0_2:
-#ifdef NO_PROMOTE_THUNKS
- if (bd->gen_no == 0 &&
- bd->step->no != 0 &&
- bd->step->no == generations[bd->gen_no].n_steps-1) {
- stp = bd->step;
- }
-#endif
- return copy(q,sizeofW(StgThunk)+2,stp);
-
- case FUN_1_1:
- case FUN_2_0:
- case FUN_0_2:
- case CONSTR_1_1:
- case CONSTR_2_0:
- return copy_tag(q,sizeofW(StgHeader)+2,stp,tag);
-
- case CONSTR_0_2:
- return copy_noscav_tag(q,sizeofW(StgHeader)+2,stp,tag);
-
- case THUNK:
- return copy(q,thunk_sizeW_fromITBL(info),stp);
-
- case FUN:
- case IND_PERM:
- case IND_OLDGEN_PERM:
- case WEAK:
- case STABLE_NAME:
- case CONSTR:
- return copy_tag(q,sizeW_fromITBL(info),stp,tag);
-
- case BCO:
- return copy(q,bco_sizeW((StgBCO *)q),stp);
-
- case CAF_BLACKHOLE:
- case SE_CAF_BLACKHOLE:
- case SE_BLACKHOLE:
- case BLACKHOLE:
- return copyPart(q,BLACKHOLE_sizeW(),sizeofW(StgHeader),stp);
-
- case THUNK_SELECTOR:
- return eval_thunk_selector((StgSelector *)q, rtsTrue);
-
- case IND:
- case IND_OLDGEN:
- // follow chains of indirections, don't evacuate them
- q = ((StgInd*)q)->indirectee;
- goto loop;
-
- case RET_BCO:
- case RET_SMALL:
- case RET_BIG:
- case RET_DYN:
- case UPDATE_FRAME:
- case STOP_FRAME:
- case CATCH_FRAME:
- case CATCH_STM_FRAME:
- case CATCH_RETRY_FRAME:
- case ATOMICALLY_FRAME:
- // shouldn't see these
- barf("evacuate: stack frame at %p\n", q);
-
- case PAP:
- return copy(q,pap_sizeW((StgPAP*)q),stp);
-
- case AP:
- return copy(q,ap_sizeW((StgAP*)q),stp);
-
- case AP_STACK:
- return copy(q,ap_stack_sizeW((StgAP_STACK*)q),stp);
-
- case EVACUATED:
- /* Already evacuated, just return the forwarding address.
- * HOWEVER: if the requested destination generation (evac_gen) is
- * older than the actual generation (because the object was
- * already evacuated to a younger generation) then we have to
- * set the failed_to_evac flag to indicate that we couldn't
- * manage to promote the object to the desired generation.
- */
- /*
- * Optimisation: the check is fairly expensive, but we can often
- * shortcut it if either the required generation is 0, or the
- * current object (the EVACUATED) is in a high enough generation.
- * We know that an EVACUATED always points to an object in the
- * same or an older generation. stp is the lowest step that the
- * current object would be evacuated to, so we only do the full
- * check if stp is too low.
- */
- if (evac_gen > 0 && stp->gen_no < evac_gen) { // optimisation
- StgClosure *p = ((StgEvacuated*)q)->evacuee;
- if (HEAP_ALLOCED(p) && Bdescr((P_)p)->gen_no < evac_gen) {
- failed_to_evac = rtsTrue;
- TICK_GC_FAILED_PROMOTION();
- }
- }
- return ((StgEvacuated*)q)->evacuee;
-
- case ARR_WORDS:
- // just copy the block
- return copy_noscav(q,arr_words_sizeW((StgArrWords *)q),stp);
-
- case MUT_ARR_PTRS_CLEAN:
- case MUT_ARR_PTRS_DIRTY:
- case MUT_ARR_PTRS_FROZEN:
- case MUT_ARR_PTRS_FROZEN0:
- // just copy the block
- return copy(q,mut_arr_ptrs_sizeW((StgMutArrPtrs *)q),stp);
-
- case TSO:
- {
- StgTSO *tso = (StgTSO *)q;
-
- /* Deal with redirected TSOs (a TSO that's had its stack enlarged).
- */
- if (tso->what_next == ThreadRelocated) {
- q = (StgClosure *)tso->link;
- goto loop;
- }
-
- /* To evacuate a small TSO, we need to relocate the update frame
- * list it contains.
- */
- {
- StgTSO *new_tso;
- StgPtr p, q;
-
- new_tso = (StgTSO *)copyPart((StgClosure *)tso,
- tso_sizeW(tso),
- sizeofW(StgTSO), stp);
- move_TSO(tso, new_tso);
- for (p = tso->sp, q = new_tso->sp;
- p < tso->stack+tso->stack_size;) {
- *q++ = *p++;
- }
-
- return (StgClosure *)new_tso;
- }
- }
-
- case TREC_HEADER:
- return copy(q,sizeofW(StgTRecHeader),stp);
-
- case TVAR_WATCH_QUEUE:
- return copy(q,sizeofW(StgTVarWatchQueue),stp);
-
- case TVAR:
- return copy(q,sizeofW(StgTVar),stp);
-
- case TREC_CHUNK:
- return copy(q,sizeofW(StgTRecChunk),stp);
-
- case ATOMIC_INVARIANT:
- return copy(q,sizeofW(StgAtomicInvariant),stp);
-
- case INVARIANT_CHECK_QUEUE:
- return copy(q,sizeofW(StgInvariantCheckQueue),stp);
-
- default:
- barf("evacuate: strange closure type %d", (int)(info->type));
- }
-
- barf("evacuate");
-}
-
static void
unchain_thunk_selectors(StgSelector *p, StgClosure *val)
{
}
}
-/* -----------------------------------------------------------------------------
- Evaluate a THUNK_SELECTOR if possible.
-
- p points to a THUNK_SELECTOR that we want to evaluate. The
- result of "evaluating" it will be evacuated and a pointer to the
- to-space closure will be returned.
-
- If the THUNK_SELECTOR could not be evaluated (its selectee is still
- a THUNK, for example), then the THUNK_SELECTOR itself will be
- evacuated.
- -------------------------------------------------------------------------- */
-
-static StgClosure *
-eval_thunk_selector (StgSelector * p, rtsBool evac)
+static void
+eval_thunk_selector (StgClosure **q, StgSelector * p, rtsBool evac)
+ // NB. for legacy reasons, p & q are swapped around :(
{
nat field;
StgInfoTable *info;
- const StgInfoTable *info_ptr;
+ StgWord info_ptr;
StgClosure *selectee;
StgSelector *prev_thunk_selector;
bdescr *bd;
selector_chain:
- // The selectee might be a constructor closure,
- // so we untag the pointer.
- selectee = UNTAG_CLOSURE(p->selectee);
-
- // Save the real info pointer (NOTE: not the same as get_itbl()).
- info_ptr = p->header.info;
- field = get_itbl(p)->layout.selector_offset;
-
bd = Bdescr((StgPtr)p);
if (HEAP_ALLOCED(p)) {
// If the THUNK_SELECTOR is in to-space or in a generation that we
// mutable list.
if ((bd->gen_no > N) || (bd->flags & BF_EVACUATED)) {
unchain_thunk_selectors(prev_thunk_selector, (StgClosure *)p);
- return (StgClosure *)p;
+ *q = (StgClosure *)p;
+ return;
}
// we don't update THUNK_SELECTORS in the compacted
// generation, because compaction does not remove the INDs
// around here, test by compiling stage 3 with +RTS -c -RTS.
if (bd->flags & BF_COMPACTED) {
// must call evacuate() to mark this closure if evac==rtsTrue
- if (evac) p = (StgSelector *)evacuate((StgClosure *)p);
+ *q = (StgClosure *)p;
+ if (evac) evacuate(q);
unchain_thunk_selectors(prev_thunk_selector, (StgClosure *)p);
- return (StgClosure *)p;
+ return;
}
}
+
// BLACKHOLE the selector thunk, since it is now under evaluation.
// This is important to stop us going into an infinite loop if
// this selector thunk eventually refers to itself.
+#if defined(THREADED_RTS)
+ // In threaded mode, we'll use WHITEHOLE to lock the selector
+ // thunk while we evaluate it.
+ {
+ info_ptr = xchg((StgPtr)&p->header.info, (W_)&stg_WHITEHOLE_info);
+ if (info_ptr == (W_)&stg_WHITEHOLE_info) {
+ do {
+ info_ptr = xchg((StgPtr)&p->header.info, (W_)&stg_WHITEHOLE_info);
+ } while (info_ptr == (W_)&stg_WHITEHOLE_info);
+ goto bale_out;
+ }
+ // make sure someone else didn't get here first
+ if (INFO_PTR_TO_STRUCT(info_ptr)->type != THUNK_SELECTOR) {
+ goto bale_out;
+ }
+ }
+#else
+ // Save the real info pointer (NOTE: not the same as get_itbl()).
+ info_ptr = (StgWord)p->header.info;
SET_INFO(p,&stg_BLACKHOLE_info);
+#endif
+
+ field = INFO_PTR_TO_STRUCT(info_ptr)->layout.selector_offset;
+
+ // The selectee might be a constructor closure,
+ // so we untag the pointer.
+ selectee = UNTAG_CLOSURE(p->selectee);
selector_loop:
// selectee now points to the closure that we're trying to select
info = get_itbl(selectee);
switch (info->type) {
+ case WHITEHOLE:
+ goto bale_out; // about to be evacuated by another thread (or a loop).
+
case CONSTR:
case CONSTR_1_0:
case CONSTR_0_1:
#ifdef PROFILING
// For the purposes of LDV profiling, we have destroyed
// the original selector thunk, p.
- SET_INFO(p, info_ptr);
+ SET_INFO(p, (StgInfoTable *)info_ptr);
LDV_RECORD_DEAD_FILL_SLOP_DYNAMIC((StgClosure *)p);
SET_INFO(p, &stg_BLACKHOLE_info);
#endif
((StgClosure*)p)->payload[0] = (StgClosure *)prev_thunk_selector;
prev_thunk_selector = p;
- if (evac) val = evacuate(val);
+ *q = val;
+ if (evac) evacuate(q);
+ val = *q;
// evacuate() cannot recurse through
// eval_thunk_selector(), because we know val is not
// a THUNK_SELECTOR.
unchain_thunk_selectors(prev_thunk_selector, val);
- return val;
+ return;
}
}
// recursively evaluate this selector. We don't want to
// recurse indefinitely, so we impose a depth bound.
- if (thunk_selector_depth >= MAX_THUNK_SELECTOR_DEPTH) {
+ if (gct->thunk_selector_depth >= MAX_THUNK_SELECTOR_DEPTH) {
goto bale_out;
}
- thunk_selector_depth++;
+ gct->thunk_selector_depth++;
// rtsFalse says "don't evacuate the result". It will,
// however, update any THUNK_SELECTORs that are evaluated
// along the way.
- val = eval_thunk_selector((StgSelector *)selectee, rtsFalse);
- thunk_selector_depth--;
+ eval_thunk_selector(&val, (StgSelector*)selectee, rtsFalse);
+ gct->thunk_selector_depth--;
// did we actually manage to evaluate it?
if (val == selectee) goto bale_out;
bale_out:
// We didn't manage to evaluate this thunk; restore the old info
// pointer. But don't forget: we still need to evacuate the thunk itself.
- SET_INFO(p, info_ptr);
+ SET_INFO(p, (const StgInfoTable *)info_ptr);
if (evac) {
- val = copy((StgClosure *)p,THUNK_SELECTOR_sizeW(),bd->step->to);
+ copy(&val,(StgClosure *)p,THUNK_SELECTOR_sizeW(),bd->step->to);
} else {
val = (StgClosure *)p;
}
+ *q = val;
unchain_thunk_selectors(prev_thunk_selector, val);
- return val;
+ return;
}
/* -----------------------------------------------------------------------------
projects / ghc-hetmet.git / blobdiff