#include "Prelude.h"
#include "ParTicky.h" // ToDo: move into Rts.h
#include "GCCompact.h"
-#include "Signals.h"
+#include "RtsSignals.h"
#include "STM.h"
#if defined(GRAN) || defined(PAR)
# include "GranSimRts.h"
*/
static nat evac_gen;
+/* Whether to do eager promotion or not.
+ */
+static rtsBool eager_promotion;
+
/* Weak pointers
*/
StgWeak *old_weak_ptr_list; // also pending finaliser list
*/
static rtsBool failed_to_evac;
-/* Old to-space (used for two-space collector only)
+/* Saved nursery (used for 2-space collector only)
*/
-static bdescr *old_to_blocks;
-
+static bdescr *saved_nursery;
+static nat saved_n_blocks;
+
/* Data used for allocation area sizing.
*/
static lnat new_blocks; // blocks allocated during this GC
+static lnat new_scavd_blocks; // ditto, but depth-first blocks
static lnat g0s0_pcnt_kept = 30; // percentage of g0s0 live at last minor GC
/* Used to avoid long recursion due to selector thunks
static lnat thunk_selector_depth = 0;
#define MAX_THUNK_SELECTOR_DEPTH 8
+/* Mut-list stats */
+#ifdef DEBUG
+static nat
+ mutlist_MUTVARS,
+ mutlist_MUTARRS,
+ mutlist_OTHERS;
+#endif
+
/* -----------------------------------------------------------------------------
Static function declarations
-------------------------------------------------------------------------- */
}
// Start a new to-space block, chain it on after the previous one.
- if (stp->hp_bd == NULL) {
- stp->hp_bd = bd;
- } else {
+ if (stp->hp_bd != NULL) {
stp->hp_bd->free = stp->hp;
stp->hp_bd->link = bd;
- stp->hp_bd = bd;
}
+ stp->hp_bd = bd;
stp->hp = bd->start;
stp->hpLim = stp->hp + BLOCK_SIZE_W;
- stp->n_to_blocks++;
+ stp->n_blocks++;
new_blocks++;
return bd;
}
+static bdescr *
+gc_alloc_scavd_block(step *stp)
+{
+ bdescr *bd = allocBlock();
+ bd->gen_no = stp->gen_no;
+ bd->step = stp;
+
+ // blocks in to-space in generations up to and including N
+ // get the BF_EVACUATED flag.
+ if (stp->gen_no <= N) {
+ bd->flags = BF_EVACUATED;
+ } else {
+ bd->flags = 0;
+ }
+
+ bd->link = stp->blocks;
+ stp->blocks = bd;
+
+ if (stp->scavd_hp != NULL) {
+ Bdescr(stp->scavd_hp)->free = stp->scavd_hp;
+ }
+ stp->scavd_hp = bd->start;
+ stp->scavd_hpLim = stp->scavd_hp + BLOCK_SIZE_W;
+
+ stp->n_blocks++;
+ new_scavd_blocks++;
+
+ return bd;
+}
+
/* -----------------------------------------------------------------------------
GarbageCollect
- free from-space in each step, and set from-space = to-space.
- Locks held: sched_mutex
+ Locks held: all capabilities are held throughout GarbageCollect().
-------------------------------------------------------------------------- */
{
bdescr *bd;
step *stp;
- lnat live, allocated, collected = 0, copied = 0;
+ lnat live, allocated, copied = 0, scavd_copied = 0;
lnat oldgen_saved_blocks = 0;
- nat g, s;
+ nat g, s, i;
+
+ ACQUIRE_SM_LOCK;
#ifdef PROFILING
CostCentreStack *prev_CCS;
// tell the stats department that we've started a GC
stat_startGC();
+#ifdef DEBUG
+ // check for memory leaks if DEBUG is on
+ memInventory();
+#endif
+
+#ifdef DEBUG
+ mutlist_MUTVARS = 0;
+ mutlist_MUTARRS = 0;
+ mutlist_OTHERS = 0;
+#endif
+
// Init stats and print par specific (timing) info
PAR_TICKY_PAR_START();
static_objects = END_OF_STATIC_LIST;
scavenged_static_objects = END_OF_STATIC_LIST;
- /* Save the old to-space if we're doing a two-space collection
+ /* Save the nursery if we're doing a two-space collection.
+ * g0s0->blocks will be used for to-space, so we need to get the
+ * nursery out of the way.
*/
if (RtsFlags.GcFlags.generations == 1) {
- old_to_blocks = g0s0->to_blocks;
- g0s0->to_blocks = NULL;
- g0s0->n_to_blocks = 0;
+ saved_nursery = g0s0->blocks;
+ saved_n_blocks = g0s0->n_blocks;
+ g0s0->blocks = NULL;
+ g0s0->n_blocks = 0;
}
/* Keep a count of how many new blocks we allocated during this GC
* (used for resizing the allocation area, later).
*/
new_blocks = 0;
+ new_scavd_blocks = 0;
// Initialise to-space in all the generations/steps that we're
// collecting.
if (g != 0) {
freeChain(generations[g].mut_list);
generations[g].mut_list = allocBlock();
+ for (i = 0; i < n_capabilities; i++) {
+ freeChain(capabilities[i].mut_lists[g]);
+ capabilities[i].mut_lists[g] = allocBlock();
+ }
}
for (s = 0; s < generations[g].n_steps; s++) {
ASSERT(stp->gen_no == g);
// start a new to-space for this step.
- stp->hp = NULL;
- stp->hp_bd = NULL;
- stp->to_blocks = NULL;
+ stp->old_blocks = stp->blocks;
+ stp->n_old_blocks = stp->n_blocks;
// allocate the first to-space block; extra blocks will be
// chained on as necessary.
+ stp->hp_bd = NULL;
bd = gc_alloc_block(stp);
- stp->to_blocks = bd;
+ stp->blocks = bd;
+ stp->n_blocks = 1;
stp->scan = bd->start;
stp->scan_bd = bd;
+ // allocate a block for "already scavenged" objects. This goes
+ // on the front of the stp->blocks list, so it won't be
+ // traversed by the scavenging sweep.
+ gc_alloc_scavd_block(stp);
+
// initialise the large object queues.
stp->new_large_objects = NULL;
stp->scavenged_large_objects = NULL;
bdescr *bitmap_bdescr;
StgWord *bitmap;
- bitmap_size = stp->n_blocks * BLOCK_SIZE / (sizeof(W_)*BITS_PER_BYTE);
+ bitmap_size = stp->n_old_blocks * BLOCK_SIZE / (sizeof(W_)*BITS_PER_BYTE);
if (bitmap_size > 0) {
bitmap_bdescr = allocGroup((lnat)BLOCK_ROUND_UP(bitmap_size)
// For each block in this step, point to its bitmap from the
// block descriptor.
- for (bd=stp->blocks; bd != NULL; bd = bd->link) {
+ for (bd=stp->old_blocks; bd != NULL; bd = bd->link) {
bd->u.bitmap = bitmap;
bitmap += BLOCK_SIZE_W / (sizeof(W_)*BITS_PER_BYTE);
stp->blocks = bd;
stp->n_blocks = 1;
}
+ if (stp->scavd_hp == NULL) {
+ gc_alloc_scavd_block(stp);
+ stp->n_blocks++;
+ }
/* Set the scan pointer for older generations: remember we
* still have to scavenge objects that have been promoted. */
stp->scan = stp->hp;
stp->scan_bd = stp->hp_bd;
- stp->to_blocks = NULL;
- stp->n_to_blocks = 0;
stp->new_large_objects = NULL;
stp->scavenged_large_objects = NULL;
stp->n_scavenged_large_blocks = 0;
}
+
+ /* Move the private mutable lists from each capability onto the
+ * main mutable list for the generation.
+ */
+ for (i = 0; i < n_capabilities; i++) {
+ for (bd = capabilities[i].mut_lists[g];
+ bd->link != NULL; bd = bd->link) {
+ /* nothing */
+ }
+ bd->link = generations[g].mut_list;
+ generations[g].mut_list = capabilities[i].mut_lists[g];
+ capabilities[i].mut_lists[g] = allocBlock();
+ }
}
/* Allocate a mark stack if we're doing a major collection.
mark_stack_bdescr = NULL;
}
+ eager_promotion = rtsTrue; // for now
+
/* -----------------------------------------------------------------------
* follow all the roots that we know about:
* - mutable lists from each generation > N
}
}
- /* Update the pointers from the "main thread" list - these are
+ /* Update the pointers from the task list - these are
* treated as weak pointers because we want to allow a main thread
* to get a BlockedOnDeadMVar exception in the same way as any other
* thread. Note that the threads should all have been retained by
* updating pointers here.
*/
{
- StgMainThread *m;
+ Task *task;
StgTSO *tso;
- for (m = main_threads; m != NULL; m = m->link) {
- tso = (StgTSO *) isAlive((StgClosure *)m->tso);
- if (tso == NULL) {
- barf("main thread has been GC'd");
+ for (task = all_tasks; task != NULL; task = task->all_link) {
+ if (!task->stopped && task->tso) {
+ ASSERT(task->tso->bound == task);
+ tso = (StgTSO *) isAlive((StgClosure *)task->tso);
+ if (tso == NULL) {
+ barf("task %p: main thread %d has been GC'd",
+#ifdef THREADED_RTS
+ (void *)task->id,
+#else
+ (void *)task,
+#endif
+ task->tso->id);
+ }
+ task->tso = tso;
}
- m->tso = tso;
}
}
if (!(g == 0 && s == 0 && RtsFlags.GcFlags.generations > 1)) {
ASSERT(Bdescr(stp->hp) == stp->hp_bd);
stp->hp_bd->free = stp->hp;
+ Bdescr(stp->scavd_hp)->free = stp->scavd_hp;
}
}
}
// Finally: compaction of the oldest generation.
if (major_gc && oldest_gen->steps[0].is_compacted) {
// save number of blocks for stats
- oldgen_saved_blocks = oldest_gen->steps[0].n_blocks;
+ oldgen_saved_blocks = oldest_gen->steps[0].n_old_blocks;
compact(get_roots);
}
/* run through all the generations/steps and tidy up
*/
copied = new_blocks * BLOCK_SIZE_W;
+ scavd_copied = new_scavd_blocks * BLOCK_SIZE_W;
for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
if (g <= N) {
// Count the mutable list as bytes "copied" for the purposes of
// stats. Every mutable list is copied during every GC.
if (g > 0) {
+ nat mut_list_size = 0;
for (bd = generations[g].mut_list; bd != NULL; bd = bd->link) {
- copied += (bd->free - bd->start) * sizeof(StgWord);
+ mut_list_size += bd->free - bd->start;
}
+ copied += mut_list_size;
+
+ IF_DEBUG(gc, debugBelch("mut_list_size: %ld (%d vars, %d arrays, %d others)\n", mut_list_size * sizeof(W_), mutlist_MUTVARS, mutlist_MUTARRS, mutlist_OTHERS));
}
for (s = 0; s < generations[g].n_steps; s++) {
if (g <= N) {
copied -= stp->hp_bd->start + BLOCK_SIZE_W -
stp->hp_bd->free;
+ scavd_copied -= (P_)(BLOCK_ROUND_UP(stp->scavd_hp)) - stp->scavd_hp;
}
}
// for generations we collected...
if (g <= N) {
- // rough calculation of garbage collected, for stats output
- if (stp->is_compacted) {
- collected += (oldgen_saved_blocks - stp->n_blocks) * BLOCK_SIZE_W;
- } else {
- collected += stp->n_blocks * BLOCK_SIZE_W;
- }
-
/* free old memory and shift to-space into from-space for all
* the collected steps (except the allocation area). These
* freed blocks will probaby be quickly recycled.
if (stp->is_compacted) {
// for a compacted step, just shift the new to-space
// onto the front of the now-compacted existing blocks.
- for (bd = stp->to_blocks; bd != NULL; bd = bd->link) {
+ for (bd = stp->blocks; bd != NULL; bd = bd->link) {
bd->flags &= ~BF_EVACUATED; // now from-space
}
// tack the new blocks on the end of the existing blocks
- if (stp->blocks == NULL) {
- stp->blocks = stp->to_blocks;
- } else {
- for (bd = stp->blocks; bd != NULL; bd = next) {
- next = bd->link;
- if (next == NULL) {
- bd->link = stp->to_blocks;
- }
+ if (stp->old_blocks != NULL) {
+ for (bd = stp->old_blocks; bd != NULL; bd = next) {
// NB. this step might not be compacted next
// time, so reset the BF_COMPACTED flags.
// They are set before GC if we're going to
// compact. (search for BF_COMPACTED above).
bd->flags &= ~BF_COMPACTED;
+ next = bd->link;
+ if (next == NULL) {
+ bd->link = stp->blocks;
+ }
}
+ stp->blocks = stp->old_blocks;
}
// add the new blocks to the block tally
- stp->n_blocks += stp->n_to_blocks;
+ stp->n_blocks += stp->n_old_blocks;
+ ASSERT(countBlocks(stp->blocks) == stp->n_blocks);
} else {
- freeChain(stp->blocks);
- stp->blocks = stp->to_blocks;
- stp->n_blocks = stp->n_to_blocks;
+ freeChain(stp->old_blocks);
for (bd = stp->blocks; bd != NULL; bd = bd->link) {
bd->flags &= ~BF_EVACUATED; // now from-space
}
}
- stp->to_blocks = NULL;
- stp->n_to_blocks = 0;
+ stp->old_blocks = NULL;
+ stp->n_old_blocks = 0;
}
/* LARGE OBJECTS. The current live large objects are chained on
}
// add the new blocks we promoted during this GC
- stp->n_blocks += stp->n_to_blocks;
- stp->n_to_blocks = 0;
stp->n_large_blocks += stp->n_scavenged_large_blocks;
}
}
for (g = 0; g <= N; g++) {
for (s = 0; s < generations[g].n_steps; s++) {
stp = &generations[g].steps[s];
- if (stp->is_compacted && stp->bitmap != NULL) {
+ if (stp->bitmap != NULL) {
freeGroup(stp->bitmap);
+ stp->bitmap = NULL;
}
}
}
if (RtsFlags.GcFlags.generations == 1) {
nat blocks;
- if (old_to_blocks != NULL) {
- freeChain(old_to_blocks);
+ if (g0s0->old_blocks != NULL) {
+ freeChain(g0s0->old_blocks);
}
- for (bd = g0s0->to_blocks; bd != NULL; bd = bd->link) {
+ for (bd = g0s0->blocks; bd != NULL; bd = bd->link) {
bd->flags = 0; // now from-space
}
+ g0s0->old_blocks = g0s0->blocks;
+ g0s0->n_old_blocks = g0s0->n_blocks;
+ g0s0->blocks = saved_nursery;
+ g0s0->n_blocks = saved_n_blocks;
/* For a two-space collector, we need to resize the nursery. */
* performance we get from 3L bytes, reducing to the same
* performance at 2L bytes.
*/
- blocks = g0s0->n_to_blocks;
+ blocks = g0s0->n_old_blocks;
if ( RtsFlags.GcFlags.maxHeapSize != 0 &&
blocks * RtsFlags.GcFlags.oldGenFactor * 2 >
} else {
// we might have added extra large blocks to the nursery, so
// resize back to minAllocAreaSize again.
- resizeNurseries(RtsFlags.GcFlags.minAllocAreaSize);
+ resizeNurseriesFixed(RtsFlags.GcFlags.minAllocAreaSize);
}
}
// Reset the nursery
resetNurseries();
- RELEASE_LOCK(&sched_mutex);
-
// start any pending finalizers
- scheduleFinalizers(old_weak_ptr_list);
+ RELEASE_SM_LOCK;
+ scheduleFinalizers(last_free_capability, old_weak_ptr_list);
+ ACQUIRE_SM_LOCK;
// send exceptions to any threads which were about to die
+ RELEASE_SM_LOCK;
resurrectThreads(resurrected_threads);
-
- ACQUIRE_LOCK(&sched_mutex);
+ ACQUIRE_SM_LOCK;
// Update the stable pointer hash table.
updateStablePtrTable(major_gc);
CCCS = prev_CCS;
#endif
- // check for memory leaks if sanity checking is on
- IF_DEBUG(sanity, memInventory());
+#ifdef DEBUG
+ // check for memory leaks if DEBUG is on
+ memInventory();
+#endif
#ifdef RTS_GTK_FRONTPANEL
if (RtsFlags.GcFlags.frontpanel) {
#endif
// ok, GC over: tell the stats department what happened.
- stat_endGC(allocated, collected, live, copied, N);
+ stat_endGC(allocated, live, copied, scavd_copied, N);
#if defined(RTS_USER_SIGNALS)
// unblock signals again
unblockUserSignals();
#endif
+ RELEASE_SM_LOCK;
+
//PAR_TICKY_TP();
}
;
}
+ // Threads blocked on black holes: if the black hole
+ // is alive, then the thread is alive too.
+ if (tmp == NULL && t->why_blocked == BlockedOnBlackHole) {
+ if (isAlive(t->block_info.closure)) {
+ t = (StgTSO *)evacuate((StgClosure *)t);
+ tmp = t;
+ flag = rtsTrue;
+ }
+ }
+
if (tmp == NULL) {
// not alive (yet): leave this thread on the
// old_all_threads list.
}
}
+ /* If we evacuated any threads, we need to go back to the scavenger.
+ */
+ if (flag) return rtsTrue;
+
/* And resurrect any threads which were about to become garbage.
*/
{
}
}
+ /* Finally, we can update the blackhole_queue. This queue
+ * simply strings together TSOs blocked on black holes, it is
+ * not intended to keep anything alive. Hence, we do not follow
+ * pointers on the blackhole_queue until now, when we have
+ * determined which TSOs are otherwise reachable. We know at
+ * this point that all TSOs have been evacuated, however.
+ */
+ {
+ StgTSO **pt;
+ for (pt = &blackhole_queue; *pt != END_TSO_QUEUE; pt = &((*pt)->link)) {
+ *pt = (StgTSO *)isAlive((StgClosure *)*pt);
+ ASSERT(*pt != NULL);
+ }
+ }
+
weak_stage = WeakDone; // *now* we're done,
return rtsTrue; // but one more round of scavenging, please
STATIC_INLINE StgClosure *
copy(StgClosure *src, nat size, step *stp)
{
- P_ to, from, dest;
+ StgPtr to, from;
+ nat i;
#ifdef PROFILING
// @LDV profiling
nat size_org = size;
* by evacuate()).
*/
if (stp->gen_no < evac_gen) {
-#ifdef NO_EAGER_PROMOTION
- failed_to_evac = rtsTrue;
-#else
- stp = &generations[evac_gen].steps[0];
-#endif
+ 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
gc_alloc_block(stp);
}
- for(to = stp->hp, from = (P_)src; size>0; --size) {
- *to++ = *from++;
+ to = stp->hp;
+ from = (StgPtr)src;
+ stp->hp = to + size;
+ for (i = 0; i < size; i++) { // unroll for small i
+ to[i] = from[i];
}
+ upd_evacuee((StgClosure *)from,(StgClosure *)to);
- dest = stp->hp;
- stp->hp = to;
- 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.
- SET_EVACUAEE_FOR_LDV(src, size_org);
+ SET_EVACUAEE_FOR_LDV(from, size_org);
#endif
- return (StgClosure *)dest;
+ return (StgClosure *)to;
+}
+
+// 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(StgClosure *src, 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];
+ }
+ 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;
}
/* Special version of copy() for when we only want to copy the info
TICK_GC_WORDS_COPIED(size_to_copy);
if (stp->gen_no < evac_gen) {
-#ifdef NO_EAGER_PROMOTION
- failed_to_evac = rtsTrue;
-#else
- stp = &generations[evac_gen].steps[0];
-#endif
+ if (eager_promotion) {
+ stp = &generations[evac_gen].steps[0];
+ } else {
+ failed_to_evac = rtsTrue;
+ }
}
if (stp->hp + size_to_reserve >= stp->hpLim) {
SET_EVACUAEE_FOR_LDV(src, size_to_reserve);
// fill the slop
if (size_to_reserve - size_to_copy_org > 0)
- FILL_SLOP(stp->hp - 1, (int)(size_to_reserve - size_to_copy_org));
+ LDV_FILL_SLOP(stp->hp - 1, (int)(size_to_reserve - size_to_copy_org));
#endif
return (StgClosure *)dest;
}
*/
stp = bd->step->to;
if (stp->gen_no < evac_gen) {
-#ifdef NO_EAGER_PROMOTION
- failed_to_evac = rtsTrue;
-#else
- stp = &generations[evac_gen].steps[0];
-#endif
+ if (eager_promotion) {
+ stp = &generations[evac_gen].steps[0];
+ } else {
+ failed_to_evac = rtsTrue;
+ }
}
bd->step = stp;
const StgInfoTable *info;
loop:
- if (HEAP_ALLOCED(q)) {
- bd = Bdescr((P_)q);
+ ASSERT(LOOKS_LIKE_CLOSURE_PTR(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 q;
- }
+ if (!HEAP_ALLOCED(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 q;
- }
+ if (!major_gc) return 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 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;
+ }
+ return q;
+
+ case CONSTR_INTLIKE:
+ case CONSTR_CHARLIKE:
+ case CONSTR_NOCAF_STATIC:
+ /* no need to put these on the static linked list, they don't need
+ * to be scavenged.
+ */
+ return q;
+
+ default:
+ barf("evacuate(static): strange closure type %d", (int)(info->type));
+ }
+ }
- /* Object is not already evacuated. */
- ASSERT((bd->flags & BF_EVACUATED) == 0);
+ bd = Bdescr((P_)q);
- stp = bd->step->to;
+ 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 q;
}
-#ifdef DEBUG
- else stp = NULL; // make sure copy() will crash if HEAP_ALLOCED is wrong
-#endif
- // make sure the info pointer is into text space
- ASSERT(LOOKS_LIKE_CLOSURE_PTR(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 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 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 q;
+ }
+ }
+
+ stp = bd->step->to;
+
info = get_itbl(q);
- switch (info -> type) {
+ switch (info->type) {
- case MUT_VAR:
+ case MUT_VAR_CLEAN:
+ case MUT_VAR_DIRTY:
case MVAR:
return copy(q,sizeW_fromITBL(info),stp);
(StgInt)w >= MIN_INTLIKE && (StgInt)w <= MAX_INTLIKE) {
return (StgClosure *)INTLIKE_CLOSURE((StgInt)w);
}
- // else, fall through ...
+ // else
+ return copy_noscav(q,sizeofW(StgHeader)+1,stp);
}
- case FUN_1_0:
case FUN_0_1:
+ case FUN_1_0:
case CONSTR_1_0:
+ return copy(q,sizeofW(StgHeader)+1,stp);
+
case THUNK_1_0:
case THUNK_0_1:
- return copy(q,sizeofW(StgHeader)+1,stp);
+ return copy(q,sizeofW(StgThunk)+1,stp);
case THUNK_1_1:
- case THUNK_0_2:
case THUNK_2_0:
+ case THUNK_0_2:
#ifdef NO_PROMOTE_THUNKS
if (bd->gen_no == 0 &&
bd->step->no != 0 &&
stp = bd->step;
}
#endif
- return copy(q,sizeofW(StgHeader)+2,stp);
+ return copy(q,sizeofW(StgThunk)+2,stp);
case FUN_1_1:
- case FUN_0_2:
case FUN_2_0:
case CONSTR_1_1:
- case CONSTR_0_2:
case CONSTR_2_0:
+ case FUN_0_2:
return copy(q,sizeofW(StgHeader)+2,stp);
- case FUN:
+ case CONSTR_0_2:
+ return copy_noscav(q,sizeofW(StgHeader)+2,stp);
+
case THUNK:
+ return copy(q,thunk_sizeW_fromITBL(info),stp);
+
+ case FUN:
case CONSTR:
case IND_PERM:
case IND_OLDGEN_PERM:
case WEAK:
- case FOREIGN:
case STABLE_NAME:
return copy(q,sizeW_fromITBL(info),stp);
case THUNK_SELECTOR:
{
StgClosure *p;
+ const StgInfoTable *info_ptr;
if (thunk_selector_depth > MAX_THUNK_SELECTOR_DEPTH) {
return copy(q,THUNK_SELECTOR_sizeW(),stp);
}
+ // stashed away for LDV profiling, see below
+ info_ptr = q->header.info;
+
p = eval_thunk_selector(info->layout.selector_offset,
(StgSelector *)q);
if (p == NULL) {
return copy(q,THUNK_SELECTOR_sizeW(),stp);
} else {
+ StgClosure *val;
// q is still BLACKHOLE'd.
thunk_selector_depth++;
- p = evacuate(p);
+ val = evacuate(p);
thunk_selector_depth--;
- upd_evacuee(q,p);
+
#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(q, THUNK_SELECTOR_sizeW());
+ // For the purposes of LDV profiling, we have destroyed
+ // the original selector thunk.
+ SET_INFO(q, info_ptr);
+ LDV_RECORD_DEAD_FILL_SLOP_DYNAMIC(q);
#endif
- return p;
+
+ // Update the THUNK_SELECTOR with an indirection to the
+ // EVACUATED closure now at p. Why do this rather than
+ // upd_evacuee(q,p)? Because we have an invariant that an
+ // EVACUATED closure always points to an object in the
+ // same or an older generation (required by the short-cut
+ // test in the EVACUATED case, below).
+ SET_INFO(q, &stg_IND_info);
+ ((StgInd *)q)->indirectee = p;
+
+ // For the purposes of LDV profiling, we have created an
+ // indirection.
+ LDV_RECORD_CREATE(q);
+
+ return val;
}
}
q = ((StgInd*)q)->indirectee;
goto loop;
- case THUNK_STATIC:
- if (info->srt_bitmap != 0 && major_gc &&
- 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 && major_gc &&
- 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 (major_gc
- && ((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 (major_gc && STATIC_LINK(info,(StgClosure *)q) == NULL) {
- STATIC_LINK(info,(StgClosure *)q) = static_objects;
- static_objects = (StgClosure *)q;
- }
- return q;
-
- case CONSTR_INTLIKE:
- case CONSTR_CHARLIKE:
- case CONSTR_NOCAF_STATIC:
- /* no need to put these on the static linked list, they don't need
- * to be scavenged.
- */
- return q;
-
case RET_BCO:
case RET_SMALL:
case RET_VEC_SMALL:
barf("evacuate: stack frame at %p\n", q);
case PAP:
- case AP:
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);
* set the failed_to_evac flag to indicate that we couldn't
* manage to promote the object to the desired generation.
*/
- if (evac_gen > 0) { // optimisation
+ /*
+ * 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;
case ARR_WORDS:
// just copy the block
- return copy(q,arr_words_sizeW((StgArrWords *)q),stp);
+ return copy_noscav(q,arr_words_sizeW((StgArrWords *)q),stp);
- case MUT_ARR_PTRS:
+ case MUT_ARR_PTRS_CLEAN:
+ case MUT_ARR_PTRS_DIRTY:
case MUT_ARR_PTRS_FROZEN:
case MUT_ARR_PTRS_FROZEN0:
// just copy the block
}
case BLOCKED_FETCH:
- ASSERT(sizeofW(StgBlockedFetch) >= MIN_NONUPD_SIZE);
+ ASSERT(sizeofW(StgBlockedFetch) >= MIN_PAYLOD_SIZE);
to = copy(q,sizeofW(StgBlockedFetch),stp);
IF_DEBUG(gc,
debugBelch("@@ evacuate: %p (%s) to %p (%s)",
case REMOTE_REF:
# endif
case FETCH_ME:
- ASSERT(sizeofW(StgBlockedFetch) >= MIN_UPD_SIZE);
+ ASSERT(sizeofW(StgBlockedFetch) >= MIN_PAYLOAD_SIZE);
to = copy(q,sizeofW(StgFetchMe),stp);
IF_DEBUG(gc,
debugBelch("@@ evacuate: %p (%s) to %p (%s)",
return to;
case FETCH_ME_BQ:
- ASSERT(sizeofW(StgBlockedFetch) >= MIN_UPD_SIZE);
+ ASSERT(sizeofW(StgBlockedFetch) >= MIN_PAYLOAD_SIZE);
to = copy(q,sizeofW(StgFetchMeBlockingQueue),stp);
IF_DEBUG(gc,
debugBelch("@@ evacuate: %p (%s) to %p (%s)",
been BLACKHOLE'd, and should be updated with an indirection or a
forwarding pointer. If the return value is NULL, then the selector
thunk is unchanged.
+
+ ***
+ ToDo: the treatment of THUNK_SELECTORS could be improved in the
+ following way (from a suggestion by Ian Lynagh):
+
+ We can have a chain like this:
+
+ sel_0 --> (a,b)
+ |
+ |-----> sel_0 --> (a,b)
+ |
+ |-----> sel_0 --> ...
+
+ and the depth limit means we don't go all the way to the end of the
+ chain, which results in a space leak. This affects the recursive
+ call to evacuate() in the THUNK_SELECTOR case in evacuate(): *not*
+ the recursive call to eval_thunk_selector() in
+ eval_thunk_selector().
+
+ We could eliminate the depth bound in this case, in the following
+ way:
+
+ - traverse the chain once to discover the *value* of the
+ THUNK_SELECTOR. Mark all THUNK_SELECTORS that we
+ visit on the way as having been visited already (somehow).
+
+ - in a second pass, traverse the chain again updating all
+ THUNK_SEELCTORS that we find on the way with indirections to
+ the value.
+
+ - if we encounter a "marked" THUNK_SELECTOR in a normal
+ evacuate(), we konw it can't be updated so just evac it.
+
+ Program that illustrates the problem:
+
+ foo [] = ([], [])
+ foo (x:xs) = let (ys, zs) = foo xs
+ in if x >= 0 then (x:ys, zs) else (ys, x:zs)
+
+ main = bar [1..(100000000::Int)]
+ bar xs = (\(ys, zs) -> print ys >> print zs) (foo xs)
+
-------------------------------------------------------------------------- */
static inline rtsBool
{
StgThunkInfoTable *thunk_info;
+ if (!major_gc) return;
+
thunk_info = itbl_to_thunk_itbl(info);
scavenge_srt((StgClosure **)GET_SRT(thunk_info), thunk_info->i.srt_bitmap);
}
{
StgFunInfoTable *fun_info;
+ if (!major_gc) return;
+
fun_info = itbl_to_fun_itbl(info);
scavenge_srt((StgClosure **)GET_FUN_SRT(fun_info), fun_info->i.srt_bitmap);
}
-STATIC_INLINE void
-scavenge_ret_srt(const StgInfoTable *info)
-{
- StgRetInfoTable *ret_info;
-
- ret_info = itbl_to_ret_itbl(info);
- scavenge_srt((StgClosure **)GET_SRT(ret_info), ret_info->i.srt_bitmap);
-}
-
/* -----------------------------------------------------------------------------
Scavenge a TSO.
-------------------------------------------------------------------------- */
static void
scavengeTSO (StgTSO *tso)
{
- // chase the link field for any TSOs on the same queue
- tso->link = (StgTSO *)evacuate((StgClosure *)tso->link);
if ( tso->why_blocked == BlockedOnMVar
|| tso->why_blocked == BlockedOnBlackHole
|| tso->why_blocked == BlockedOnException
(StgTSO *)evacuate((StgClosure *)tso->blocked_exceptions);
}
+ // 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) {
+ tso->link = (StgTSO *)evacuate((StgClosure *)tso->link);
+ }
+
// scavange current transaction record
tso->trec = (StgTRecHeader *)evacuate((StgClosure *)tso->trec);
}
STATIC_INLINE StgPtr
-scavenge_PAP (StgPAP *pap)
+scavenge_PAP_payload (StgClosure *fun, StgClosure **payload, StgWord size)
{
StgPtr p;
- StgWord bitmap, size;
+ StgWord bitmap;
StgFunInfoTable *fun_info;
-
- pap->fun = evacuate(pap->fun);
- fun_info = get_fun_itbl(pap->fun);
+
+ fun_info = get_fun_itbl(fun);
ASSERT(fun_info->i.type != PAP);
-
- p = (StgPtr)pap->payload;
- size = pap->n_args;
+ p = (StgPtr)payload;
switch (fun_info->f.fun_type) {
case ARG_GEN:
p += size;
break;
case ARG_BCO:
- scavenge_large_bitmap((StgPtr)pap->payload, BCO_BITMAP(pap->fun), size);
+ scavenge_large_bitmap((StgPtr)payload, BCO_BITMAP(fun), size);
p += size;
break;
default:
bitmap = BITMAP_BITS(stg_arg_bitmaps[fun_info->f.fun_type]);
small_bitmap:
- size = pap->n_args;
while (size > 0) {
if ((bitmap & 1) == 0) {
*p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
return p;
}
+STATIC_INLINE StgPtr
+scavenge_PAP (StgPAP *pap)
+{
+ pap->fun = evacuate(pap->fun);
+ return scavenge_PAP_payload (pap->fun, pap->payload, pap->n_args);
+}
+
+STATIC_INLINE StgPtr
+scavenge_AP (StgAP *ap)
+{
+ ap->fun = evacuate(ap->fun);
+ return scavenge_PAP_payload (ap->fun, ap->payload, ap->n_args);
+}
+
/* -----------------------------------------------------------------------------
Scavenge a given step until there are no more objects in this step
to scavenge.
case THUNK_2_0:
scavenge_thunk_srt(info);
+ ((StgThunk *)p)->payload[1] = evacuate(((StgThunk *)p)->payload[1]);
+ ((StgThunk *)p)->payload[0] = evacuate(((StgThunk *)p)->payload[0]);
+ p += sizeofW(StgThunk) + 2;
+ break;
+
case CONSTR_2_0:
((StgClosure *)p)->payload[1] = evacuate(((StgClosure *)p)->payload[1]);
((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]);
case THUNK_1_0:
scavenge_thunk_srt(info);
- ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]);
- p += sizeofW(StgHeader) + 1;
+ ((StgThunk *)p)->payload[0] = evacuate(((StgThunk *)p)->payload[0]);
+ p += sizeofW(StgThunk) + 1;
break;
case FUN_1_0:
case THUNK_0_1:
scavenge_thunk_srt(info);
- p += sizeofW(StgHeader) + 1;
+ p += sizeofW(StgThunk) + 1;
break;
case FUN_0_1:
case THUNK_0_2:
scavenge_thunk_srt(info);
- p += sizeofW(StgHeader) + 2;
+ p += sizeofW(StgThunk) + 2;
break;
case FUN_0_2:
case THUNK_1_1:
scavenge_thunk_srt(info);
- ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]);
- p += sizeofW(StgHeader) + 2;
+ ((StgThunk *)p)->payload[0] = evacuate(((StgThunk *)p)->payload[0]);
+ p += sizeofW(StgThunk) + 2;
break;
case FUN_1_1:
goto gen_obj;
case THUNK:
+ {
+ StgPtr end;
+
scavenge_thunk_srt(info);
- // fall through
+ end = (P_)((StgThunk *)p)->payload + info->layout.payload.ptrs;
+ for (p = (P_)((StgThunk *)p)->payload; p < end; p++) {
+ *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
+ }
+ p += info->layout.payload.nptrs;
+ break;
+ }
gen_obj:
case CONSTR:
case WEAK:
- case FOREIGN:
case STABLE_NAME:
{
StgPtr end;
p += sizeofW(StgInd);
break;
- case MUT_VAR:
- evac_gen = 0;
+ case MUT_VAR_CLEAN:
+ case MUT_VAR_DIRTY: {
+ rtsBool saved_eager_promotion = eager_promotion;
+
+ eager_promotion = rtsFalse;
((StgMutVar *)p)->var = evacuate(((StgMutVar *)p)->var);
- evac_gen = saved_evac_gen;
- failed_to_evac = rtsTrue; // mutable anyhow
+ eager_promotion = saved_eager_promotion;
+
+ if (failed_to_evac) {
+ ((StgClosure *)q)->header.info = &stg_MUT_VAR_DIRTY_info;
+ } else {
+ ((StgClosure *)q)->header.info = &stg_MUT_VAR_CLEAN_info;
+ }
p += sizeofW(StgMutVar);
break;
+ }
case CAF_BLACKHOLE:
case SE_CAF_BLACKHOLE:
}
case PAP:
- case AP:
p = scavenge_PAP((StgPAP *)p);
break;
+ case AP:
+ p = scavenge_AP((StgAP *)p);
+ break;
+
case ARR_WORDS:
// nothing to follow
p += arr_words_sizeW((StgArrWords *)p);
break;
- case MUT_ARR_PTRS:
+ case MUT_ARR_PTRS_CLEAN:
+ case MUT_ARR_PTRS_DIRTY:
// follow everything
{
StgPtr next;
-
- evac_gen = 0; // repeatedly mutable
+ 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 = eager_promotion;
+ eager_promotion = rtsFalse;
next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p);
for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) {
*p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
}
- evac_gen = saved_evac_gen;
- failed_to_evac = rtsTrue; // mutable anyhow.
+ eager_promotion = saved_eager;
+
+ if (failed_to_evac) {
+ ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_DIRTY_info;
+ } else {
+ ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_CLEAN_info;
+ }
+
+ failed_to_evac = rtsTrue; // always put it on the mutable list.
break;
}
for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) {
*p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
}
- // it's tempting to recordMutable() if failed_to_evac is
- // false, but that breaks some assumptions (eg. every
- // closure on the mutable list is supposed to have the MUT
- // flag set, and MUT_ARR_PTRS_FROZEN doesn't).
+
+ // If we're going to put this object on the mutable list, then
+ // set its info ptr to MUT_ARR_PTRS_FROZEN0 to indicate that.
+ if (failed_to_evac) {
+ ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_FROZEN0_info;
+ } else {
+ ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_FROZEN_info;
+ }
break;
}
case TSO:
{
StgTSO *tso = (StgTSO *)p;
- evac_gen = 0;
+ rtsBool saved_eager = eager_promotion;
+
+ eager_promotion = rtsFalse;
scavengeTSO(tso);
- evac_gen = saved_evac_gen;
- failed_to_evac = rtsTrue; // mutable anyhow.
+ eager_promotion = saved_eager;
+
+ if (failed_to_evac) {
+ tso->flags |= TSO_DIRTY;
+ } else {
+ tso->flags &= ~TSO_DIRTY;
+ }
+
+ failed_to_evac = rtsTrue; // always on the mutable list
p += tso_sizeW(tso);
break;
}
*/
if (failed_to_evac) {
failed_to_evac = rtsFalse;
- recordMutableGen((StgClosure *)q, stp->gen);
+ if (stp->gen_no > 0) {
+ recordMutableGen((StgClosure *)q, stp->gen);
+ }
}
}
case THUNK_2_0:
scavenge_thunk_srt(info);
+ ((StgThunk *)p)->payload[1] = evacuate(((StgThunk *)p)->payload[1]);
+ ((StgThunk *)p)->payload[0] = evacuate(((StgThunk *)p)->payload[0]);
+ break;
+
case CONSTR_2_0:
((StgClosure *)p)->payload[1] = evacuate(((StgClosure *)p)->payload[1]);
((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]);
case THUNK_1_0:
case THUNK_1_1:
scavenge_thunk_srt(info);
+ ((StgThunk *)p)->payload[0] = evacuate(((StgThunk *)p)->payload[0]);
+ break;
+
case CONSTR_1_0:
case CONSTR_1_1:
((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]);
goto gen_obj;
case THUNK:
+ {
+ StgPtr end;
+
scavenge_thunk_srt(info);
- // fall through
+ end = (P_)((StgThunk *)p)->payload + info->layout.payload.ptrs;
+ for (p = (P_)((StgThunk *)p)->payload; p < end; p++) {
+ *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
+ }
+ break;
+ }
gen_obj:
case CONSTR:
case WEAK:
- case FOREIGN:
case STABLE_NAME:
{
StgPtr end;
evacuate(((StgInd *)p)->indirectee);
break;
- case MUT_VAR:
- evac_gen = 0;
+ case MUT_VAR_CLEAN:
+ case MUT_VAR_DIRTY: {
+ rtsBool saved_eager_promotion = eager_promotion;
+
+ eager_promotion = rtsFalse;
((StgMutVar *)p)->var = evacuate(((StgMutVar *)p)->var);
- evac_gen = saved_evac_gen;
- failed_to_evac = rtsTrue;
+ eager_promotion = saved_eager_promotion;
+
+ if (failed_to_evac) {
+ ((StgClosure *)q)->header.info = &stg_MUT_VAR_DIRTY_info;
+ } else {
+ ((StgClosure *)q)->header.info = &stg_MUT_VAR_CLEAN_info;
+ }
break;
+ }
case CAF_BLACKHOLE:
case SE_CAF_BLACKHOLE:
}
case PAP:
- case AP:
scavenge_PAP((StgPAP *)p);
break;
+
+ case AP:
+ scavenge_AP((StgAP *)p);
+ break;
- case MUT_ARR_PTRS:
+ case MUT_ARR_PTRS_CLEAN:
+ case MUT_ARR_PTRS_DIRTY:
// follow everything
{
StgPtr next;
-
- evac_gen = 0; // repeatedly mutable
+ 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 = eager_promotion;
+ eager_promotion = rtsFalse;
next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p);
for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) {
*p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
}
- evac_gen = saved_evac_gen;
+ eager_promotion = saved_eager;
+
+ if (failed_to_evac) {
+ ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_DIRTY_info;
+ } else {
+ ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_CLEAN_info;
+ }
+
failed_to_evac = rtsTrue; // mutable anyhow.
break;
}
case MUT_ARR_PTRS_FROZEN0:
// follow everything
{
- StgPtr next;
+ StgPtr next, q = p;
next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p);
for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) {
*p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
}
+
+ // If we're going to put this object on the mutable list, then
+ // set its info ptr to MUT_ARR_PTRS_FROZEN0 to indicate that.
+ if (failed_to_evac) {
+ ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_FROZEN0_info;
+ } else {
+ ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_FROZEN_info;
+ }
break;
}
case TSO:
{
StgTSO *tso = (StgTSO *)p;
- evac_gen = 0;
+ rtsBool saved_eager = eager_promotion;
+
+ eager_promotion = rtsFalse;
scavengeTSO(tso);
- evac_gen = saved_evac_gen;
- failed_to_evac = rtsTrue;
+ eager_promotion = saved_eager;
+
+ if (failed_to_evac) {
+ tso->flags |= TSO_DIRTY;
+ } else {
+ tso->flags &= ~TSO_DIRTY;
+ }
+
+ failed_to_evac = rtsTrue; // always on the mutable list
break;
}
if (failed_to_evac) {
failed_to_evac = rtsFalse;
- recordMutableGen((StgClosure *)q, &generations[evac_gen]);
+ if (evac_gen > 0) {
+ recordMutableGen((StgClosure *)q, &generations[evac_gen]);
+ }
}
// mark the next bit to indicate "scavenged"
if (mark_stack_overflowed && oldgen_scan_bd == NULL) {
IF_DEBUG(gc, debugBelch("scavenge_mark_stack: starting linear scan"));
mark_stack_overflowed = rtsFalse;
- oldgen_scan_bd = oldest_gen->steps[0].blocks;
+ oldgen_scan_bd = oldest_gen->steps[0].old_blocks;
oldgen_scan = oldgen_scan_bd->start;
}
// already scavenged?
if (is_marked(oldgen_scan+1,oldgen_scan_bd)) {
- oldgen_scan += sizeofW(StgHeader) + MIN_NONUPD_SIZE;
+ oldgen_scan += sizeofW(StgHeader) + MIN_PAYLOAD_SIZE;
goto loop;
}
push_mark_stack(oldgen_scan);
// ToDo: bump the linear scan by the actual size of the object
- oldgen_scan += sizeofW(StgHeader) + MIN_NONUPD_SIZE;
+ oldgen_scan += sizeofW(StgHeader) + MIN_PAYLOAD_SIZE;
goto linear_scan;
}
break;
}
- case FUN:
- case FUN_1_0: // hardly worth specialising these guys
- case FUN_0_1:
- case FUN_1_1:
- case FUN_0_2:
- case FUN_2_0:
case THUNK:
case THUNK_1_0:
case THUNK_0_1:
case THUNK_1_1:
case THUNK_0_2:
case THUNK_2_0:
+ {
+ StgPtr q, end;
+
+ end = (StgPtr)((StgThunk *)p)->payload + info->layout.payload.ptrs;
+ for (q = (StgPtr)((StgThunk *)p)->payload; q < end; q++) {
+ *q = (StgWord)(StgPtr)evacuate((StgClosure *)*q);
+ }
+ break;
+ }
+
+ case FUN:
+ case FUN_1_0: // hardly worth specialising these guys
+ case FUN_0_1:
+ case FUN_1_1:
+ case FUN_0_2:
+ case FUN_2_0:
case CONSTR:
case CONSTR_1_0:
case CONSTR_0_1:
case CONSTR_0_2:
case CONSTR_2_0:
case WEAK:
- case FOREIGN:
case IND_PERM:
{
StgPtr q, end;
break;
}
- case MUT_VAR:
- evac_gen = 0;
+ case MUT_VAR_CLEAN:
+ case MUT_VAR_DIRTY: {
+ StgPtr q = p;
+ rtsBool saved_eager_promotion = eager_promotion;
+
+ eager_promotion = rtsFalse;
((StgMutVar *)p)->var = evacuate(((StgMutVar *)p)->var);
- evac_gen = saved_evac_gen;
- failed_to_evac = rtsTrue; // mutable anyhow
+ eager_promotion = saved_eager_promotion;
+
+ if (failed_to_evac) {
+ ((StgClosure *)q)->header.info = &stg_MUT_VAR_DIRTY_info;
+ } else {
+ ((StgClosure *)q)->header.info = &stg_MUT_VAR_CLEAN_info;
+ }
break;
+ }
case CAF_BLACKHOLE:
case SE_CAF_BLACKHOLE:
}
case PAP:
- case AP:
p = scavenge_PAP((StgPAP *)p);
break;
+ case AP:
+ p = scavenge_AP((StgAP *)p);
+ break;
+
case ARR_WORDS:
// nothing to follow
break;
- case MUT_ARR_PTRS:
+ case MUT_ARR_PTRS_CLEAN:
+ case MUT_ARR_PTRS_DIRTY:
{
- // follow everything
- StgPtr next;
-
- evac_gen = 0; // repeatedly mutable
+ StgPtr next, q;
+ 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 = eager_promotion;
+ eager_promotion = rtsFalse;
+ q = p;
next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p);
for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) {
*p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
}
- evac_gen = saved_evac_gen;
+ eager_promotion = saved_eager;
+
+ if (failed_to_evac) {
+ ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_DIRTY_info;
+ } else {
+ ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_CLEAN_info;
+ }
+
failed_to_evac = rtsTrue;
break;
}
case MUT_ARR_PTRS_FROZEN0:
{
// follow everything
- StgPtr next;
+ StgPtr next, q=p;
next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p);
for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) {
*p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
}
+
+ // If we're going to put this object on the mutable list, then
+ // set its info ptr to MUT_ARR_PTRS_FROZEN0 to indicate that.
+ if (failed_to_evac) {
+ ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_FROZEN0_info;
+ } else {
+ ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_FROZEN_info;
+ }
break;
}
case TSO:
{
StgTSO *tso = (StgTSO *)p;
-
- evac_gen = 0; // repeatedly mutable
+ rtsBool saved_eager = eager_promotion;
+
+ eager_promotion = rtsFalse;
scavengeTSO(tso);
- evac_gen = saved_evac_gen;
- failed_to_evac = rtsTrue;
+ eager_promotion = saved_eager;
+
+ if (failed_to_evac) {
+ tso->flags |= TSO_DIRTY;
+ } else {
+ tso->flags &= ~TSO_DIRTY;
+ }
+
+ failed_to_evac = rtsTrue; // always on the mutable list
break;
}
for (q = bd->start; q < bd->free; q++) {
p = (StgPtr)*q;
ASSERT(LOOKS_LIKE_CLOSURE_PTR(p));
+
+#ifdef DEBUG
+ switch (get_itbl((StgClosure *)p)->type) {
+ case MUT_VAR_CLEAN:
+ barf("MUT_VAR_CLEAN on mutable list");
+ case MUT_VAR_DIRTY:
+ mutlist_MUTVARS++; break;
+ case MUT_ARR_PTRS_CLEAN:
+ case MUT_ARR_PTRS_DIRTY:
+ case MUT_ARR_PTRS_FROZEN:
+ case MUT_ARR_PTRS_FROZEN0:
+ mutlist_MUTARRS++; break;
+ default:
+ mutlist_OTHERS++; break;
+ }
+#endif
+
+ // Check whether this object is "clean", that is it
+ // definitely doesn't point into a young generation.
+ // Clean objects don't need to be scavenged. Some clean
+ // objects (MUT_VAR_CLEAN) are not kept on the mutable
+ // list at all; others, such as MUT_ARR_PTRS_CLEAN and
+ // TSO, are always on the mutable list.
+ //
+ switch (get_itbl((StgClosure *)p)->type) {
+ case MUT_ARR_PTRS_CLEAN:
+ recordMutableGen((StgClosure *)p,gen);
+ continue;
+ case TSO: {
+ StgTSO *tso = (StgTSO *)p;
+ if ((tso->flags & TSO_DIRTY) == 0) {
+ // A clean TSO: we don't have to traverse its
+ // stack. However, we *do* follow the link field:
+ // we don't want to have to mark a TSO dirty just
+ // because we put it on a different queue.
+ if (tso->why_blocked != BlockedOnBlackHole) {
+ tso->link = (StgTSO *)evacuate((StgClosure *)tso->link);
+ }
+ recordMutableGen((StgClosure *)p,gen);
+ continue;
+ }
+ }
+ default:
+ ;
+ }
+
if (scavenge_one(p)) {
- /* didn't manage to promote everything, so put the
- * object back on the list.
- */
+ // didn't manage to promote everything, so put the
+ // object back on the list.
recordMutableGen((StgClosure *)p,gen);
}
}
/* Take this object *off* the static_objects list,
* and put it on the scavenged_static_objects list.
*/
- static_objects = STATIC_LINK(info,p);
- STATIC_LINK(info,p) = scavenged_static_objects;
+ static_objects = *STATIC_LINK(info,p);
+ *STATIC_LINK(info,p) = scavenged_static_objects;
scavenged_static_objects = p;
switch (info -> type) {
switch (info->i.type) {
case UPDATE_FRAME:
+ // In SMP, we can get update frames that point to indirections
+ // when two threads evaluate the same thunk. We do attempt to
+ // discover this situation in threadPaused(), but it's
+ // possible that the following sequence occurs:
+ //
+ // A B
+ // enter T
+ // enter T
+ // blackhole T
+ // update T
+ // GC
+ //
+ // Now T is an indirection, and the update frame is already
+ // marked on A's stack, so we won't traverse it again in
+ // threadPaused(). We could traverse the whole stack again
+ // 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.
+ if (get_itbl(((StgUpdateFrame *)p)->updatee)->type == IND) {
+ ((StgUpdateFrame *)p)->updatee->header.info =
+ (StgInfoTable *)&stg_IND_PERM_info;
+ }
((StgUpdateFrame *)p)->updatee
= evacuate(((StgUpdateFrame *)p)->updatee);
p += sizeofW(StgUpdateFrame);
p = scavenge_small_bitmap(p, size, bitmap);
follow_srt:
- scavenge_srt((StgClosure **)GET_SRT(info), info->i.srt_bitmap);
+ if (major_gc)
+ scavenge_srt((StgClosure **)GET_SRT(info), info->i.srt_bitmap);
continue;
case RET_BCO: {
p = bd->start;
if (scavenge_one(p)) {
- recordMutableGen((StgClosure *)p, stp->gen);
+ if (stp->gen_no > 0) {
+ recordMutableGen((StgClosure *)p, stp->gen);
+ }
}
}
}
for (p = first_static; p != END_OF_STATIC_LIST; p = link) {
info = get_itbl(p);
- link = STATIC_LINK(info, p);
- STATIC_LINK(info,p) = NULL;
+ link = *STATIC_LINK(info, p);
+ *STATIC_LINK(info,p) = NULL;
}
}
/* -----------------------------------------------------------------------------
- Lazy black holing.
-
- Whenever a thread returns to the scheduler after possibly doing
- some work, we have to run down the stack and black-hole all the
- closures referred to by update frames.
- -------------------------------------------------------------------------- */
-
-static void
-threadLazyBlackHole(StgTSO *tso)
-{
- StgClosure *frame;
- StgRetInfoTable *info;
- StgClosure *bh;
- StgPtr stack_end;
-
- stack_end = &tso->stack[tso->stack_size];
-
- frame = (StgClosure *)tso->sp;
-
- while (1) {
- info = get_ret_itbl(frame);
-
- switch (info->i.type) {
-
- case UPDATE_FRAME:
- bh = ((StgUpdateFrame *)frame)->updatee;
-
- /* if the thunk is already blackholed, it means we've also
- * already blackholed the rest of the thunks on this stack,
- * so we can stop early.
- *
- * The blackhole made for a CAF is a CAF_BLACKHOLE, so they
- * don't interfere with this optimisation.
- */
- if (bh->header.info == &stg_BLACKHOLE_info) {
- return;
- }
-
- if (bh->header.info != &stg_CAF_BLACKHOLE_info) {
-#if (!defined(LAZY_BLACKHOLING)) && defined(DEBUG)
- debugBelch("Unexpected lazy BHing required at 0x%04x\n",(int)bh);
-#endif
-#ifdef PROFILING
- // @LDV profiling
- // We pretend that bh is now dead.
- LDV_recordDead_FILL_SLOP_DYNAMIC((StgClosure *)bh);
-#endif
- SET_INFO(bh,&stg_BLACKHOLE_info);
-
- // We pretend that bh has just been created.
- LDV_RECORD_CREATE(bh);
- }
-
- frame = (StgClosure *) ((StgUpdateFrame *)frame + 1);
- break;
-
- case STOP_FRAME:
- return;
-
- // normal stack frames; do nothing except advance the pointer
- default:
- frame = (StgClosure *)((StgPtr)frame + stack_frame_sizeW(frame));
- }
- }
-}
-
-
-/* -----------------------------------------------------------------------------
* Stack squeezing
*
* Code largely pinched from old RTS, then hacked to bits. We also do
struct stack_gap { StgWord gap_size; struct stack_gap *next_gap; };
static void
-threadSqueezeStack(StgTSO *tso)
+stackSqueeze(StgTSO *tso, StgPtr bottom)
{
StgPtr frame;
rtsBool prev_was_update_frame;
StgClosure *updatee = NULL;
- StgPtr bottom;
StgRetInfoTable *info;
StgWord current_gap_size;
struct stack_gap *gap;
// contains two values: the size of the gap, and the distance
// to the next gap (or the stack top).
- bottom = &(tso->stack[tso->stack_size]);
-
frame = tso->sp;
ASSERT(frame < bottom);
{
StgUpdateFrame *upd = (StgUpdateFrame *)frame;
- if (upd->updatee->header.info == &stg_BLACKHOLE_info) {
-
- // found a BLACKHOLE'd update frame; we've been here
- // before, in a previous GC, so just break out.
-
- // Mark the end of the gap, if we're in one.
- if (current_gap_size != 0) {
- gap = (struct stack_gap *)(frame-sizeofW(StgUpdateFrame));
- }
-
- frame += sizeofW(StgUpdateFrame);
- goto done_traversing;
- }
-
if (prev_was_update_frame) {
TICK_UPD_SQUEEZED();
// single update frame, or the topmost update frame in a series
else {
- StgClosure *bh = upd->updatee;
-
- // Do lazy black-holing
- if (bh->header.info != &stg_BLACKHOLE_info &&
- bh->header.info != &stg_CAF_BLACKHOLE_info) {
-#if (!defined(LAZY_BLACKHOLING)) && defined(DEBUG)
- debugBelch("Unexpected lazy BHing required at 0x%04x",(int)bh);
-#endif
-#ifdef DEBUG
- /* zero out the slop so that the sanity checker can tell
- * where the next closure is.
- */
- {
- StgInfoTable *bh_info = get_itbl(bh);
- nat np = bh_info->layout.payload.ptrs,
- nw = bh_info->layout.payload.nptrs, i;
- /* don't zero out slop for a THUNK_SELECTOR,
- * because its layout info is used for a
- * different purpose, and it's exactly the
- * same size as a BLACKHOLE in any case.
- */
- if (bh_info->type != THUNK_SELECTOR) {
- for (i = 0; i < np + nw; i++) {
- ((StgClosure *)bh)->payload[i] = INVALID_OBJECT;
- }
- }
- }
-#endif
-#ifdef PROFILING
- // We pretend that bh is now dead.
- LDV_recordDead_FILL_SLOP_DYNAMIC((StgClosure *)bh);
-#endif
- // Todo: maybe use SET_HDR() and remove LDV_RECORD_CREATE()?
- SET_INFO(bh,&stg_BLACKHOLE_info);
-
- // We pretend that bh has just been created.
- LDV_RECORD_CREATE(bh);
- }
-
prev_was_update_frame = rtsTrue;
updatee = upd->updatee;
frame += sizeofW(StgUpdateFrame);
}
}
-done_traversing:
-
+ if (current_gap_size != 0) {
+ gap = (struct stack_gap *) (frame - sizeofW(StgUpdateFrame));
+ }
+
// Now we have a stack with gaps in it, and we have to walk down
// shoving the stack up to fill in the gaps. A diagram might
// help:
* turned on.
* -------------------------------------------------------------------------- */
void
-threadPaused(StgTSO *tso)
+threadPaused(Capability *cap, StgTSO *tso)
{
- if ( RtsFlags.GcFlags.squeezeUpdFrames == rtsTrue )
- threadSqueezeStack(tso); // does black holing too
- else
- threadLazyBlackHole(tso);
+ StgClosure *frame;
+ StgRetInfoTable *info;
+ StgClosure *bh;
+ StgPtr stack_end;
+ nat words_to_squeeze = 0;
+ nat weight = 0;
+ nat weight_pending = 0;
+ rtsBool prev_was_update_frame;
+
+ stack_end = &tso->stack[tso->stack_size];
+
+ frame = (StgClosure *)tso->sp;
+
+ while (1) {
+ // If we've already marked this frame, then stop here.
+ if (frame->header.info == (StgInfoTable *)&stg_marked_upd_frame_info) {
+ goto end;
+ }
+
+ info = get_ret_itbl(frame);
+
+ switch (info->i.type) {
+
+ case UPDATE_FRAME:
+
+ SET_INFO(frame, (StgInfoTable *)&stg_marked_upd_frame_info);
+
+ bh = ((StgUpdateFrame *)frame)->updatee;
+
+ if (closure_IND(bh) || bh->header.info == &stg_BLACKHOLE_info) {
+ IF_DEBUG(squeeze, debugBelch("suspending duplicate work: %ld words of stack\n", (StgPtr)frame - tso->sp));
+
+ // If this closure is already an indirection, then
+ // suspend the computation up to this point:
+ suspendComputation(cap,tso,(StgPtr)frame);
+
+ // Now drop the update frame, and arrange to return
+ // the value to the frame underneath:
+ tso->sp = (StgPtr)frame + sizeofW(StgUpdateFrame) - 2;
+ tso->sp[1] = (StgWord)bh;
+ tso->sp[0] = (W_)&stg_enter_info;
+
+ // And continue with threadPaused; there might be
+ // yet more computation to suspend.
+ threadPaused(cap,tso);
+ return;
+ }
+
+ if (bh->header.info != &stg_CAF_BLACKHOLE_info) {
+#if (!defined(LAZY_BLACKHOLING)) && defined(DEBUG)
+ debugBelch("Unexpected lazy BHing required at 0x%04lx\n",(long)bh);
+#endif
+ // zero out the slop so that the sanity checker can tell
+ // where the next closure is.
+ DEBUG_FILL_SLOP(bh);
+#ifdef PROFILING
+ // @LDV profiling
+ // We pretend that bh is now dead.
+ LDV_recordDead_FILL_SLOP_DYNAMIC((StgClosure *)bh);
+#endif
+ SET_INFO(bh,&stg_BLACKHOLE_info);
+
+ // We pretend that bh has just been created.
+ LDV_RECORD_CREATE(bh);
+ }
+
+ frame = (StgClosure *) ((StgUpdateFrame *)frame + 1);
+ if (prev_was_update_frame) {
+ words_to_squeeze += sizeofW(StgUpdateFrame);
+ weight += weight_pending;
+ weight_pending = 0;
+ }
+ prev_was_update_frame = rtsTrue;
+ break;
+
+ case STOP_FRAME:
+ goto end;
+
+ // normal stack frames; do nothing except advance the pointer
+ default:
+ {
+ nat frame_size = stack_frame_sizeW(frame);
+ weight_pending += frame_size;
+ frame = (StgClosure *)((StgPtr)frame + frame_size);
+ prev_was_update_frame = rtsFalse;
+ }
+ }
+ }
+
+end:
+ IF_DEBUG(squeeze,
+ debugBelch("words_to_squeeze: %d, weight: %d, squeeze: %s\n",
+ words_to_squeeze, weight,
+ weight < words_to_squeeze ? "YES" : "NO"));
+
+ // Should we squeeze or not? Arbitrary heuristic: we squeeze if
+ // the number of words we have to shift down is less than the
+ // number of stack words we squeeze away by doing so.
+ if (RtsFlags.GcFlags.squeezeUpdFrames == rtsTrue &&
+ weight < words_to_squeeze) {
+ stackSqueeze(tso, (StgPtr)frame);
+ }
}
/* -----------------------------------------------------------------------------
}
debugBelch("\n");
}
-
-STATIC_INLINE rtsBool
-maybeLarge(StgClosure *closure)
-{
- StgInfoTable *info = get_itbl(closure);
-
- /* closure types that may be found on the new_large_objects list;
- see scavenge_large */
- return (info->type == MUT_ARR_PTRS ||
- info->type == MUT_ARR_PTRS_FROZEN ||
- info->type == MUT_ARR_PTRS_FROZEN0 ||
- info->type == TSO ||
- info->type == ARR_WORDS);
-}
-
-
#endif /* DEBUG */
projects / ghc-hetmet.git / blobdiff