#if defined(THREADED_RTS) && !defined(PARALLEL_GC)
# define evacuate(a) evacuate1(a)
-# define recordMutableGen_GC(a,b) recordMutableGen(a,b)
# define scavenge_loop(a) scavenge_loop1(a)
# define scavenge_block(a) scavenge_block1(a)
# define scavenge_mutable_list(bd,g) scavenge_mutable_list1(bd,g)
Scavenge a TSO.
-------------------------------------------------------------------------- */
-STATIC_INLINE void
-scavenge_TSO_link (StgTSO *tso)
-{
- // We don't always chase the link field: TSOs on the blackhole
- // queue are not automatically alive, so the link field is a
- // "weak" pointer in that case.
- if (tso->why_blocked != BlockedOnBlackHole) {
- evacuate((StgClosure **)&tso->_link);
- }
-}
-
static void
scavengeTSO (StgTSO *tso)
{
saved_eager = gct->eager_promotion;
gct->eager_promotion = rtsFalse;
- if ( tso->why_blocked == BlockedOnMVar
- || tso->why_blocked == BlockedOnBlackHole
- || tso->why_blocked == BlockedOnException
- ) {
- evacuate(&tso->block_info.closure);
- }
+
evacuate((StgClosure **)&tso->blocked_exceptions);
+ evacuate((StgClosure **)&tso->bq);
// scavange current transaction record
evacuate((StgClosure **)&tso->trec);
// scavenge this thread's stack
scavenge_stack(tso->sp, &(tso->stack[tso->stack_size]));
- if (gct->failed_to_evac) {
- tso->dirty = 1;
- scavenge_TSO_link(tso);
+ tso->dirty = gct->failed_to_evac;
+
+ evacuate((StgClosure **)&tso->_link);
+ if ( tso->why_blocked == BlockedOnMVar
+ || tso->why_blocked == BlockedOnBlackHole
+ || tso->why_blocked == BlockedOnMsgThrowTo
+ || tso->why_blocked == NotBlocked
+ ) {
+ evacuate(&tso->block_info.closure);
+ }
+#ifdef THREADED_RTS
+ // in the THREADED_RTS, block_info.closure must always point to a
+ // valid closure, because we assume this in throwTo(). In the
+ // non-threaded RTS it might be a FD (for
+ // BlockedOnRead/BlockedOnWrite) or a time value (BlockedOnDelay)
+ else {
+ tso->block_info.closure = (StgClosure *)END_TSO_QUEUE;
+ }
+#endif
+
+ if (tso->dirty == 0 && gct->failed_to_evac) {
+ tso->flags |= TSO_LINK_DIRTY;
} else {
- tso->dirty = 0;
- scavenge_TSO_link(tso);
- if (gct->failed_to_evac) {
- tso->flags |= TSO_LINK_DIRTY;
- } else {
- tso->flags &= ~TSO_LINK_DIRTY;
- }
+ tso->flags &= ~TSO_LINK_DIRTY;
}
gct->eager_promotion = saved_eager;
while (bitmap != 0) {
if ((bitmap & 1) != 0) {
-#if defined(__PIC__) && defined(mingw32_TARGET_OS)
+#if defined(__PIC__) && defined(mingw32_HOST_OS)
// Special-case to handle references to closures hiding out in DLLs, since
// double indirections required to get at those. The code generator knows
// which is which when generating the SRT, so it stores the (indirect)
{
StgPtr p, q;
StgInfoTable *info;
- generation *saved_evac_gen;
rtsBool saved_eager_promotion;
gen_workspace *ws;
gct->scan_bd = bd;
gct->evac_gen = bd->gen;
- saved_evac_gen = gct->evac_gen;
saved_eager_promotion = gct->eager_promotion;
gct->failed_to_evac = rtsFalse;
gen_obj:
case CONSTR:
case WEAK:
- case STABLE_NAME:
+ case PRIM:
{
StgPtr end;
}
case IND_PERM:
- if (bd->gen_no != 0) {
-#ifdef PROFILING
- // @LDV profiling
- // No need to call LDV_recordDead_FILL_SLOP_DYNAMIC() because an
- // IND_OLDGEN_PERM closure is larger than an IND_PERM closure.
- LDV_recordDead((StgClosure *)p, sizeofW(StgInd));
-#endif
- //
- // Todo: maybe use SET_HDR() and remove LDV_RECORD_CREATE()?
- //
- SET_INFO(((StgClosure *)p), &stg_IND_OLDGEN_PERM_info);
-
- // We pretend that p has just been created.
- LDV_RECORD_CREATE((StgClosure *)p);
- }
- // fall through
- case IND_OLDGEN_PERM:
+ case BLACKHOLE:
evacuate(&((StgInd *)p)->indirectee);
p += sizeofW(StgInd);
break;
p += sizeofW(StgMutVar);
break;
- case CAF_BLACKHOLE:
- case BLACKHOLE:
- p += BLACKHOLE_sizeW();
- break;
+ case BLOCKING_QUEUE:
+ {
+ StgBlockingQueue *bq = (StgBlockingQueue *)p;
+
+ gct->eager_promotion = rtsFalse;
+ evacuate(&bq->bh);
+ evacuate((StgClosure**)&bq->owner);
+ evacuate((StgClosure**)&bq->queue);
+ evacuate((StgClosure**)&bq->link);
+ gct->eager_promotion = saved_eager_promotion;
+
+ if (gct->failed_to_evac) {
+ bq->header.info = &stg_BLOCKING_QUEUE_DIRTY_info;
+ } else {
+ bq->header.info = &stg_BLOCKING_QUEUE_CLEAN_info;
+ }
+ p += sizeofW(StgBlockingQueue);
+ break;
+ }
case THUNK_SELECTOR:
{
break;
}
- case TVAR_WATCH_QUEUE:
+ case MUT_PRIM:
{
- StgTVarWatchQueue *wq = ((StgTVarWatchQueue *) p);
- gct->evac_gen = 0;
- evacuate((StgClosure **)&wq->closure);
- evacuate((StgClosure **)&wq->next_queue_entry);
- evacuate((StgClosure **)&wq->prev_queue_entry);
- gct->evac_gen = saved_evac_gen;
- gct->failed_to_evac = rtsTrue; // mutable
- p += sizeofW(StgTVarWatchQueue);
- break;
- }
+ StgPtr end;
- case TVAR:
- {
- StgTVar *tvar = ((StgTVar *) p);
- gct->evac_gen = 0;
- evacuate((StgClosure **)&tvar->current_value);
- evacuate((StgClosure **)&tvar->first_watch_queue_entry);
- gct->evac_gen = saved_evac_gen;
- gct->failed_to_evac = rtsTrue; // mutable
- p += sizeofW(StgTVar);
- break;
- }
+ gct->eager_promotion = rtsFalse;
- case TREC_HEADER:
- {
- StgTRecHeader *trec = ((StgTRecHeader *) p);
- gct->evac_gen = 0;
- evacuate((StgClosure **)&trec->enclosing_trec);
- evacuate((StgClosure **)&trec->current_chunk);
- evacuate((StgClosure **)&trec->invariants_to_check);
- gct->evac_gen = saved_evac_gen;
+ end = (P_)((StgClosure *)p)->payload + info->layout.payload.ptrs;
+ for (p = (P_)((StgClosure *)p)->payload; p < end; p++) {
+ evacuate((StgClosure **)p);
+ }
+ p += info->layout.payload.nptrs;
+
+ gct->eager_promotion = saved_eager_promotion;
gct->failed_to_evac = rtsTrue; // mutable
- p += sizeofW(StgTRecHeader);
- break;
+ break;
}
case TREC_CHUNK:
StgWord i;
StgTRecChunk *tc = ((StgTRecChunk *) p);
TRecEntry *e = &(tc -> entries[0]);
- gct->evac_gen = 0;
+ gct->eager_promotion = rtsFalse;
evacuate((StgClosure **)&tc->prev_chunk);
for (i = 0; i < tc -> next_entry_idx; i ++, e++ ) {
evacuate((StgClosure **)&e->tvar);
evacuate((StgClosure **)&e->expected_value);
evacuate((StgClosure **)&e->new_value);
}
- gct->evac_gen = saved_evac_gen;
+ gct->eager_promotion = saved_eager_promotion;
gct->failed_to_evac = rtsTrue; // mutable
p += sizeofW(StgTRecChunk);
break;
}
- case ATOMIC_INVARIANT:
- {
- StgAtomicInvariant *invariant = ((StgAtomicInvariant *) p);
- gct->evac_gen = 0;
- evacuate(&invariant->code);
- evacuate((StgClosure **)&invariant->last_execution);
- gct->evac_gen = saved_evac_gen;
- gct->failed_to_evac = rtsTrue; // mutable
- p += sizeofW(StgAtomicInvariant);
- break;
- }
-
- case INVARIANT_CHECK_QUEUE:
- {
- StgInvariantCheckQueue *queue = ((StgInvariantCheckQueue *) p);
- gct->evac_gen = 0;
- evacuate((StgClosure **)&queue->invariant);
- evacuate((StgClosure **)&queue->my_execution);
- evacuate((StgClosure **)&queue->next_queue_entry);
- gct->evac_gen = saved_evac_gen;
- gct->failed_to_evac = rtsTrue; // mutable
- p += sizeofW(StgInvariantCheckQueue);
- break;
- }
-
default:
barf("scavenge: unimplemented/strange closure type %d @ %p",
info->type, p);
{
StgPtr p, q;
StgInfoTable *info;
- generation *saved_evac_gen;
+ rtsBool saved_eager_promotion;
gct->evac_gen = oldest_gen;
- saved_evac_gen = gct->evac_gen;
+ saved_eager_promotion = gct->eager_promotion;
while ((p = pop_mark_stack())) {
case MVAR_CLEAN:
case MVAR_DIRTY:
{
- rtsBool saved_eager_promotion = gct->eager_promotion;
-
StgMVar *mvar = ((StgMVar *)p);
gct->eager_promotion = rtsFalse;
evacuate((StgClosure **)&mvar->head);
gen_obj:
case CONSTR:
case WEAK:
- case STABLE_NAME:
+ case PRIM:
{
StgPtr end;
// no "old" generation.
break;
- case IND_OLDGEN:
- case IND_OLDGEN_PERM:
+ case IND:
+ case BLACKHOLE:
evacuate(&((StgInd *)p)->indirectee);
break;
case MUT_VAR_CLEAN:
case MUT_VAR_DIRTY: {
- rtsBool saved_eager_promotion = gct->eager_promotion;
-
gct->eager_promotion = rtsFalse;
evacuate(&((StgMutVar *)p)->var);
gct->eager_promotion = saved_eager_promotion;
break;
}
- case CAF_BLACKHOLE:
- case BLACKHOLE:
+ case BLOCKING_QUEUE:
+ {
+ StgBlockingQueue *bq = (StgBlockingQueue *)p;
+
+ gct->eager_promotion = rtsFalse;
+ evacuate(&bq->bh);
+ evacuate((StgClosure**)&bq->owner);
+ evacuate((StgClosure**)&bq->queue);
+ evacuate((StgClosure**)&bq->link);
+ gct->eager_promotion = saved_eager_promotion;
+
+ if (gct->failed_to_evac) {
+ bq->header.info = &stg_BLOCKING_QUEUE_DIRTY_info;
+ } else {
+ bq->header.info = &stg_BLOCKING_QUEUE_CLEAN_info;
+ }
+ break;
+ }
+
case ARR_WORDS:
break;
case MUT_ARR_PTRS_DIRTY:
// follow everything
{
- rtsBool saved_eager;
-
// We don't eagerly promote objects pointed to by a mutable
// array, but if we find the array only points to objects in
// the same or an older generation, we mark it "clean" and
// avoid traversing it during minor GCs.
- saved_eager = gct->eager_promotion;
gct->eager_promotion = rtsFalse;
scavenge_mut_arr_ptrs((StgMutArrPtrs *)p);
((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_CLEAN_info;
}
- gct->eager_promotion = saved_eager;
+ gct->eager_promotion = saved_eager_promotion;
gct->failed_to_evac = rtsTrue; // mutable anyhow.
break;
}
break;
}
- case TVAR_WATCH_QUEUE:
- {
- StgTVarWatchQueue *wq = ((StgTVarWatchQueue *) p);
- gct->evac_gen = 0;
- evacuate((StgClosure **)&wq->closure);
- evacuate((StgClosure **)&wq->next_queue_entry);
- evacuate((StgClosure **)&wq->prev_queue_entry);
- gct->evac_gen = saved_evac_gen;
- gct->failed_to_evac = rtsTrue; // mutable
- break;
- }
-
- case TVAR:
- {
- StgTVar *tvar = ((StgTVar *) p);
- gct->evac_gen = 0;
- evacuate((StgClosure **)&tvar->current_value);
- evacuate((StgClosure **)&tvar->first_watch_queue_entry);
- gct->evac_gen = saved_evac_gen;
- gct->failed_to_evac = rtsTrue; // mutable
- break;
- }
-
+ case MUT_PRIM:
+ {
+ StgPtr end;
+
+ gct->eager_promotion = rtsFalse;
+
+ end = (P_)((StgClosure *)p)->payload + info->layout.payload.ptrs;
+ for (p = (P_)((StgClosure *)p)->payload; p < end; p++) {
+ evacuate((StgClosure **)p);
+ }
+
+ gct->eager_promotion = saved_eager_promotion;
+ gct->failed_to_evac = rtsTrue; // mutable
+ break;
+ }
+
case TREC_CHUNK:
{
StgWord i;
StgTRecChunk *tc = ((StgTRecChunk *) p);
TRecEntry *e = &(tc -> entries[0]);
- gct->evac_gen = 0;
+ gct->eager_promotion = rtsFalse;
evacuate((StgClosure **)&tc->prev_chunk);
for (i = 0; i < tc -> next_entry_idx; i ++, e++ ) {
evacuate((StgClosure **)&e->tvar);
evacuate((StgClosure **)&e->expected_value);
evacuate((StgClosure **)&e->new_value);
}
- gct->evac_gen = saved_evac_gen;
- gct->failed_to_evac = rtsTrue; // mutable
- break;
- }
-
- case TREC_HEADER:
- {
- StgTRecHeader *trec = ((StgTRecHeader *) p);
- gct->evac_gen = 0;
- evacuate((StgClosure **)&trec->enclosing_trec);
- evacuate((StgClosure **)&trec->current_chunk);
- evacuate((StgClosure **)&trec->invariants_to_check);
- gct->evac_gen = saved_evac_gen;
+ gct->eager_promotion = saved_eager_promotion;
gct->failed_to_evac = rtsTrue; // mutable
break;
}
- case ATOMIC_INVARIANT:
- {
- StgAtomicInvariant *invariant = ((StgAtomicInvariant *) p);
- gct->evac_gen = 0;
- evacuate(&invariant->code);
- evacuate((StgClosure **)&invariant->last_execution);
- gct->evac_gen = saved_evac_gen;
- gct->failed_to_evac = rtsTrue; // mutable
- break;
- }
-
- case INVARIANT_CHECK_QUEUE:
- {
- StgInvariantCheckQueue *queue = ((StgInvariantCheckQueue *) p);
- gct->evac_gen = 0;
- evacuate((StgClosure **)&queue->invariant);
- evacuate((StgClosure **)&queue->my_execution);
- evacuate((StgClosure **)&queue->next_queue_entry);
- gct->evac_gen = saved_evac_gen;
- gct->failed_to_evac = rtsTrue; // mutable
- break;
- }
-
default:
barf("scavenge_mark_stack: unimplemented/strange closure type %d @ %p",
info->type, p);
scavenge_one(StgPtr p)
{
const StgInfoTable *info;
- generation *saved_evac_gen = gct->evac_gen;
rtsBool no_luck;
+ rtsBool saved_eager_promotion;
+ saved_eager_promotion = gct->eager_promotion;
+
ASSERT(LOOKS_LIKE_CLOSURE_PTR(p));
info = get_itbl((StgClosure *)p);
case MVAR_CLEAN:
case MVAR_DIRTY:
{
- rtsBool saved_eager_promotion = gct->eager_promotion;
-
StgMVar *mvar = ((StgMVar *)p);
gct->eager_promotion = rtsFalse;
evacuate((StgClosure **)&mvar->head);
case CONSTR_0_2:
case CONSTR_2_0:
case WEAK:
+ case PRIM:
case IND_PERM:
{
StgPtr q, end;
case MUT_VAR_CLEAN:
case MUT_VAR_DIRTY: {
StgPtr q = p;
- rtsBool saved_eager_promotion = gct->eager_promotion;
gct->eager_promotion = rtsFalse;
evacuate(&((StgMutVar *)p)->var);
break;
}
- case CAF_BLACKHOLE:
- case BLACKHOLE:
- break;
-
+ case BLOCKING_QUEUE:
+ {
+ StgBlockingQueue *bq = (StgBlockingQueue *)p;
+
+ gct->eager_promotion = rtsFalse;
+ evacuate(&bq->bh);
+ evacuate((StgClosure**)&bq->owner);
+ evacuate((StgClosure**)&bq->queue);
+ evacuate((StgClosure**)&bq->link);
+ gct->eager_promotion = saved_eager_promotion;
+
+ if (gct->failed_to_evac) {
+ bq->header.info = &stg_BLOCKING_QUEUE_DIRTY_info;
+ } else {
+ bq->header.info = &stg_BLOCKING_QUEUE_CLEAN_info;
+ }
+ break;
+ }
+
case THUNK_SELECTOR:
{
StgSelector *s = (StgSelector *)p;
case MUT_ARR_PTRS_CLEAN:
case MUT_ARR_PTRS_DIRTY:
{
- rtsBool saved_eager;
-
// We don't eagerly promote objects pointed to by a mutable
// array, but if we find the array only points to objects in
// the same or an older generation, we mark it "clean" and
// avoid traversing it during minor GCs.
- saved_eager = gct->eager_promotion;
gct->eager_promotion = rtsFalse;
scavenge_mut_arr_ptrs((StgMutArrPtrs *)p);
((StgClosure *)p)->header.info = &stg_MUT_ARR_PTRS_CLEAN_info;
}
- gct->eager_promotion = saved_eager;
+ gct->eager_promotion = saved_eager_promotion;
gct->failed_to_evac = rtsTrue;
break;
}
break;
}
- case TVAR_WATCH_QUEUE:
- {
- StgTVarWatchQueue *wq = ((StgTVarWatchQueue *) p);
- gct->evac_gen = 0;
- evacuate((StgClosure **)&wq->closure);
- evacuate((StgClosure **)&wq->next_queue_entry);
- evacuate((StgClosure **)&wq->prev_queue_entry);
- gct->evac_gen = saved_evac_gen;
- gct->failed_to_evac = rtsTrue; // mutable
- break;
- }
+ case MUT_PRIM:
+ {
+ StgPtr end;
+
+ gct->eager_promotion = rtsFalse;
+
+ end = (P_)((StgClosure *)p)->payload + info->layout.payload.ptrs;
+ for (p = (P_)((StgClosure *)p)->payload; p < end; p++) {
+ evacuate((StgClosure **)p);
+ }
- case TVAR:
- {
- StgTVar *tvar = ((StgTVar *) p);
- gct->evac_gen = 0;
- evacuate((StgClosure **)&tvar->current_value);
- evacuate((StgClosure **)&tvar->first_watch_queue_entry);
- gct->evac_gen = saved_evac_gen;
+ gct->eager_promotion = saved_eager_promotion;
gct->failed_to_evac = rtsTrue; // mutable
break;
- }
- case TREC_HEADER:
- {
- StgTRecHeader *trec = ((StgTRecHeader *) p);
- gct->evac_gen = 0;
- evacuate((StgClosure **)&trec->enclosing_trec);
- evacuate((StgClosure **)&trec->current_chunk);
- evacuate((StgClosure **)&trec->invariants_to_check);
- gct->evac_gen = saved_evac_gen;
- gct->failed_to_evac = rtsTrue; // mutable
- break;
- }
+ }
case TREC_CHUNK:
{
StgWord i;
StgTRecChunk *tc = ((StgTRecChunk *) p);
TRecEntry *e = &(tc -> entries[0]);
- gct->evac_gen = 0;
+ gct->eager_promotion = rtsFalse;
evacuate((StgClosure **)&tc->prev_chunk);
for (i = 0; i < tc -> next_entry_idx; i ++, e++ ) {
evacuate((StgClosure **)&e->tvar);
evacuate((StgClosure **)&e->expected_value);
evacuate((StgClosure **)&e->new_value);
}
- gct->evac_gen = saved_evac_gen;
+ gct->eager_promotion = saved_eager_promotion;
gct->failed_to_evac = rtsTrue; // mutable
break;
}
- case ATOMIC_INVARIANT:
- {
- StgAtomicInvariant *invariant = ((StgAtomicInvariant *) p);
- gct->evac_gen = 0;
- evacuate(&invariant->code);
- evacuate((StgClosure **)&invariant->last_execution);
- gct->evac_gen = saved_evac_gen;
- gct->failed_to_evac = rtsTrue; // mutable
- break;
- }
-
- case INVARIANT_CHECK_QUEUE:
- {
- StgInvariantCheckQueue *queue = ((StgInvariantCheckQueue *) p);
- gct->evac_gen = 0;
- evacuate((StgClosure **)&queue->invariant);
- evacuate((StgClosure **)&queue->my_execution);
- evacuate((StgClosure **)&queue->next_queue_entry);
- gct->evac_gen = saved_evac_gen;
- gct->failed_to_evac = rtsTrue; // mutable
- break;
- }
-
case IND:
// IND can happen, for example, when the interpreter allocates
// a gigantic AP closure (more than one block), which ends up
// on the large-object list and then gets updated. See #3424.
- case IND_OLDGEN:
- case IND_OLDGEN_PERM:
+ case BLACKHOLE:
case IND_STATIC:
evacuate(&((StgInd *)p)->indirectee);
#ifdef DEBUG
switch (get_itbl((StgClosure *)p)->type) {
case MUT_VAR_CLEAN:
- barf("MUT_VAR_CLEAN on mutable list");
+ // can happen due to concurrent writeMutVars
case MUT_VAR_DIRTY:
mutlist_MUTVARS++; break;
case MUT_ARR_PTRS_CLEAN:
continue;
case MUT_ARR_PTRS_DIRTY:
{
- rtsBool saved_eager;
- saved_eager = gct->eager_promotion;
+ rtsBool saved_eager_promotion;
+ saved_eager_promotion = gct->eager_promotion;
gct->eager_promotion = rtsFalse;
scavenge_mut_arr_ptrs_marked((StgMutArrPtrs *)p);
((StgClosure *)p)->header.info = &stg_MUT_ARR_PTRS_CLEAN_info;
}
- gct->eager_promotion = saved_eager;
+ gct->eager_promotion = saved_eager_promotion;
gct->failed_to_evac = rtsFalse;
recordMutableGen_GC((StgClosure *)p,gen->no);
continue;
case TSO: {
StgTSO *tso = (StgTSO *)p;
if (tso->dirty == 0) {
- // Must be on the mutable list because its link
- // field is dirty.
- ASSERT(tso->flags & TSO_LINK_DIRTY);
-
- scavenge_TSO_link(tso);
+ // Should be on the mutable list because its link
+ // field is dirty. However, in parallel GC we may
+ // have a thread on multiple mutable lists, so
+ // this assertion would be invalid:
+ // ASSERT(tso->flags & TSO_LINK_DIRTY);
+
+ evacuate((StgClosure **)&tso->_link);
+ if ( tso->why_blocked == BlockedOnMVar
+ || tso->why_blocked == BlockedOnBlackHole
+ || tso->why_blocked == BlockedOnMsgThrowTo
+ || tso->why_blocked == NotBlocked
+ ) {
+ evacuate((StgClosure **)&tso->block_info.prev);
+ }
if (gct->failed_to_evac) {
recordMutableGen_GC((StgClosure *)p,gen->no);
gct->failed_to_evac = rtsFalse;
static void
scavenge_large_bitmap( StgPtr p, StgLargeBitmap *large_bitmap, nat size )
{
- nat i, b;
+ nat i, j, b;
StgWord bitmap;
b = 0;
- bitmap = large_bitmap->bitmap[b];
- for (i = 0; i < size; ) {
- if ((bitmap & 1) == 0) {
- evacuate((StgClosure **)p);
- }
- i++;
- p++;
- if (i % BITS_IN(W_) == 0) {
- b++;
- bitmap = large_bitmap->bitmap[b];
- } else {
+
+ for (i = 0; i < size; b++) {
+ bitmap = large_bitmap->bitmap[b];
+ j = stg_min(size-i, BITS_IN(W_));
+ i += j;
+ for (; j > 0; j--, p++) {
+ if ((bitmap & 1) == 0) {
+ evacuate((StgClosure **)p);
+ }
bitmap = bitmap >> 1;
- }
+ }
}
}
// before GC, but that seems like overkill.
//
// Scavenging this update frame as normal would be disastrous;
- // the updatee would end up pointing to the value. So we turn
- // the indirection into an IND_PERM, so that evacuate will
- // copy the indirection into the old generation instead of
- // discarding it.
+ // the updatee would end up pointing to the value. So we
+ // check whether the value after evacuation is a BLACKHOLE,
+ // and if not, we change the update frame to an stg_enter
+ // frame that simply returns the value. Hence, blackholing is
+ // compulsory (otherwise we would have to check for thunks
+ // too).
//
// Note [upd-black-hole]
// One slight hiccup is that the THUNK_SELECTOR machinery can
// the updatee is never a THUNK_SELECTOR and we're ok.
// NB. this is a new invariant: blackholing is not optional.
{
- nat type;
- const StgInfoTable *i;
- StgClosure *updatee;
-
- updatee = ((StgUpdateFrame *)p)->updatee;
- i = updatee->header.info;
- if (!IS_FORWARDING_PTR(i)) {
- type = get_itbl(updatee)->type;
- if (type == IND) {
- updatee->header.info = &stg_IND_PERM_info;
- } else if (type == IND_OLDGEN) {
- updatee->header.info = &stg_IND_OLDGEN_PERM_info;
- }
+ StgUpdateFrame *frame = (StgUpdateFrame *)p;
+ StgClosure *v;
+
+ evacuate(&frame->updatee);
+ v = frame->updatee;
+ if (GET_CLOSURE_TAG(v) != 0 ||
+ (get_itbl(v)->type != BLACKHOLE)) {
+ // blackholing is compulsory, see above.
+ frame->header.info = (const StgInfoTable*)&stg_enter_checkbh_info;
}
- evacuate(&((StgUpdateFrame *)p)->updatee);
- ASSERT(GET_CLOSURE_TAG(((StgUpdateFrame *)p)->updatee) == 0);
+ ASSERT(v->header.info != &stg_TSO_info);
p += sizeofW(StgUpdateFrame);
continue;
}
projects / ghc-hetmet.git / blobdiff