/* -----------------------------------------------------------------------------
- * $Id: GC.c,v 1.2 1998/12/02 13:28:23 simonm Exp $
+ * $Id: GC.c,v 1.52 1999/03/15 16:53:11 simonm Exp $
*
- * Two-space garbage collector
+ * (c) The GHC Team 1998-1999
+ *
+ * Generational garbage collector
*
* ---------------------------------------------------------------------------*/
#include "DebugProf.h"
#include "SchedAPI.h"
#include "Weak.h"
+#include "StablePriv.h"
StgCAF* enteredCAFs;
-static P_ toHp; /* to-space heap pointer */
-static P_ toHpLim; /* end of current to-space block */
-static bdescr *toHp_bd; /* descriptor of current to-space block */
-static nat blocks = 0; /* number of to-space blocks allocated */
-static bdescr *old_to_space = NULL; /* to-space from the last GC */
-static nat old_to_space_blocks = 0; /* size of previous to-space */
-
/* STATIC OBJECT LIST.
*
+ * During GC:
* We maintain a linked list of static objects that are still live.
* The requirements for this list are:
*
*
* An object is on the list if its static link field is non-zero; this
* means that we have to mark the end of the list with '1', not NULL.
+ *
+ * Extra notes for generational GC:
+ *
+ * Each generation has a static object list associated with it. When
+ * collecting generations up to N, we treat the static object lists
+ * from generations > N as roots.
+ *
+ * We build up a static object list while collecting generations 0..N,
+ * which is then appended to the static object list of generation N+1.
+ */
+StgClosure* static_objects; /* live static objects */
+StgClosure* scavenged_static_objects; /* static objects scavenged so far */
+
+/* N is the oldest generation being collected, where the generations
+ * are numbered starting at 0. A major GC (indicated by the major_gc
+ * flag) is when we're collecting all generations. We only attempt to
+ * deal with static objects and GC CAFs when doing a major GC.
*/
-#define END_OF_STATIC_LIST stgCast(StgClosure*,1)
-static StgClosure* static_objects;
-static StgClosure* scavenged_static_objects;
+static nat N;
+static rtsBool major_gc;
+
+/* Youngest generation that objects should be evacuated to in
+ * evacuate(). (Logically an argument to evacuate, but it's static
+ * a lot of the time so we optimise it into a global variable).
+ */
+static nat evac_gen;
/* WEAK POINTERS
*/
static StgWeak *old_weak_ptr_list; /* also pending finaliser list */
static rtsBool weak_done; /* all done for this pass */
-/* LARGE OBJECTS.
+/* Flag indicating failure to evacuate an object to the desired
+ * generation.
+ */
+static rtsBool failed_to_evac;
+
+/* Old to-space (used for two-space collector only)
+ */
+bdescr *old_to_space;
+
+/* Data used for allocation area sizing.
*/
-static bdescr *new_large_objects; /* large objects evacuated so far */
-static bdescr *scavenged_large_objects; /* large objects scavenged */
+lnat new_blocks; /* blocks allocated during this GC */
+lnat g0s0_pcnt_kept = 30; /* percentage of g0s0 live at last minor GC */
/* -----------------------------------------------------------------------------
Static function declarations
-------------------------------------------------------------------------- */
-static StgClosure *evacuate(StgClosure *q);
-static void zeroStaticObjectList(StgClosure* first_static);
-static void scavenge_stack(StgPtr p, StgPtr stack_end);
-static void scavenge_static(void);
-static void scavenge_large(void);
-static StgPtr scavenge(StgPtr to_scan);
-static rtsBool traverse_weak_ptr_list(void);
-static void revertDeadCAFs(void);
+static StgClosure * evacuate ( StgClosure *q );
+static void zero_static_object_list ( StgClosure* first_static );
+static void zero_mutable_list ( StgMutClosure *first );
+static void revert_dead_CAFs ( void );
+
+static rtsBool traverse_weak_ptr_list ( void );
+static void cleanup_weak_ptr_list ( StgWeak **list );
+
+static void scavenge_stack ( StgPtr p, StgPtr stack_end );
+static void scavenge_large ( step *step );
+static void scavenge ( step *step );
+static void scavenge_static ( void );
+static void scavenge_mutable_list ( generation *g );
+static void scavenge_mut_once_list ( generation *g );
#ifdef DEBUG
-static void gcCAFs(void);
+static void gcCAFs ( void );
#endif
/* -----------------------------------------------------------------------------
GarbageCollect
- This function performs a full copying garbage collection.
+ For garbage collecting generation N (and all younger generations):
+
+ - follow all pointers in the root set. the root set includes all
+ mutable objects in all steps in all generations.
+
+ - for each pointer, evacuate the object it points to into either
+ + to-space in the next higher step in that generation, if one exists,
+ + if the object's generation == N, then evacuate it to the next
+ generation if one exists, or else to-space in the current
+ generation.
+ + if the object's generation < N, then evacuate it to to-space
+ in the next generation.
+
+ - repeatedly scavenge to-space from each step in each generation
+ being collected until no more objects can be evacuated.
+
+ - free from-space in each step, and set from-space = to-space.
+
-------------------------------------------------------------------------- */
void GarbageCollect(void (*get_roots)(void))
{
- bdescr *bd, *scan_bd, *to_space;
- StgPtr scan;
- lnat allocated, live;
- nat old_nursery_blocks = nursery_blocks; /* for stats */
- nat old_live_blocks = old_to_space_blocks; /* ditto */
+ bdescr *bd;
+ step *step;
+ lnat live, allocated, collected = 0, copied = 0;
+ nat g, s;
+
#ifdef PROFILING
CostCentreStack *prev_CCS;
#endif
* which case we need to call threadPaused() because the scheduler
* won't have done it.
*/
- if (CurrentTSO)
- threadPaused(CurrentTSO);
+ if (CurrentTSO) { threadPaused(CurrentTSO); }
/* Approximate how much we allocated: number of blocks in the
* nursery + blocks allocated via allocate() - unused nusery blocks.
for ( bd = current_nursery->link; bd != NULL; bd = bd->link ) {
allocated -= BLOCK_SIZE_W;
}
-
+ if (current_nursery->free < current_nursery->start + BLOCK_SIZE_W) {
+ allocated -= (current_nursery->start + BLOCK_SIZE_W)
+ - current_nursery->free;
+ }
+
+ /* Figure out which generation to collect
+ */
+ N = 0;
+ for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
+ if (generations[g].steps[0].n_blocks >= generations[g].max_blocks) {
+ N = g;
+ }
+ }
+ major_gc = (N == RtsFlags.GcFlags.generations-1);
+
/* check stack sanity *before* GC (ToDo: check all threads) */
/*IF_DEBUG(sanity, checkTSO(MainTSO,0)); */
IF_DEBUG(sanity, checkFreeListSanity());
+ /* Initialise the static object lists
+ */
static_objects = END_OF_STATIC_LIST;
scavenged_static_objects = END_OF_STATIC_LIST;
- new_large_objects = NULL;
- scavenged_large_objects = NULL;
+ /* zero the mutable list for the oldest generation (see comment by
+ * zero_mutable_list below).
+ */
+ if (major_gc) {
+ zero_mutable_list(generations[RtsFlags.GcFlags.generations-1].mut_once_list);
+ }
+
+ /* Save the old to-space if we're doing a two-space collection
+ */
+ if (RtsFlags.GcFlags.generations == 1) {
+ old_to_space = g0s0->to_space;
+ g0s0->to_space = NULL;
+ }
+
+ /* Keep a count of how many new blocks we allocated during this GC
+ * (used for resizing the allocation area, later).
+ */
+ new_blocks = 0;
+
+ /* Initialise to-space in all the generations/steps that we're
+ * collecting.
+ */
+ for (g = 0; g <= N; g++) {
+ generations[g].mut_once_list = END_MUT_LIST;
+ generations[g].mut_list = END_MUT_LIST;
+
+ for (s = 0; s < generations[g].n_steps; s++) {
+
+ /* generation 0, step 0 doesn't need to-space */
+ if (g == 0 && s == 0 && RtsFlags.GcFlags.generations > 1) {
+ continue;
+ }
+
+ /* Get a free block for to-space. Extra blocks will be chained on
+ * as necessary.
+ */
+ bd = allocBlock();
+ step = &generations[g].steps[s];
+ ASSERT(step->gen->no == g);
+ ASSERT(step->hp ? Bdescr(step->hp)->step == step : rtsTrue);
+ bd->gen = &generations[g];
+ bd->step = step;
+ bd->link = NULL;
+ bd->evacuated = 1; /* it's a to-space block */
+ step->hp = bd->start;
+ step->hpLim = step->hp + BLOCK_SIZE_W;
+ step->hp_bd = bd;
+ step->to_space = bd;
+ step->to_blocks = 1;
+ step->scan = bd->start;
+ step->scan_bd = bd;
+ step->new_large_objects = NULL;
+ step->scavenged_large_objects = NULL;
+ new_blocks++;
+ /* mark the large objects as not evacuated yet */
+ for (bd = step->large_objects; bd; bd = bd->link) {
+ bd->evacuated = 0;
+ }
+ }
+ }
+
+ /* make sure the older generations have at least one block to
+ * allocate into (this makes things easier for copy(), see below.
+ */
+ for (g = N+1; g < RtsFlags.GcFlags.generations; g++) {
+ for (s = 0; s < generations[g].n_steps; s++) {
+ step = &generations[g].steps[s];
+ if (step->hp_bd == NULL) {
+ bd = allocBlock();
+ bd->gen = &generations[g];
+ bd->step = step;
+ bd->link = NULL;
+ bd->evacuated = 0; /* *not* a to-space block */
+ step->hp = bd->start;
+ step->hpLim = step->hp + BLOCK_SIZE_W;
+ step->hp_bd = bd;
+ step->blocks = bd;
+ step->n_blocks = 1;
+ new_blocks++;
+ }
+ /* Set the scan pointer for older generations: remember we
+ * still have to scavenge objects that have been promoted. */
+ step->scan = step->hp;
+ step->scan_bd = step->hp_bd;
+ step->to_space = NULL;
+ step->to_blocks = 0;
+ step->new_large_objects = NULL;
+ step->scavenged_large_objects = NULL;
+ }
+ }
+
+ /* -----------------------------------------------------------------------
+ * follow all the roots that we know about:
+ * - mutable lists from each generation > N
+ * we want to *scavenge* these roots, not evacuate them: they're not
+ * going to move in this GC.
+ * Also: do them in reverse generation order. This is because we
+ * often want to promote objects that are pointed to by older
+ * generations early, so we don't have to repeatedly copy them.
+ * Doing the generations in reverse order ensures that we don't end
+ * up in the situation where we want to evac an object to gen 3 and
+ * it has already been evaced to gen 2.
+ */
+ {
+ int st;
+ for (g = RtsFlags.GcFlags.generations-1; g > N; g--) {
+ generations[g].saved_mut_list = generations[g].mut_list;
+ generations[g].mut_list = END_MUT_LIST;
+ }
+
+ /* Do the mut-once lists first */
+ for (g = RtsFlags.GcFlags.generations-1; g > N; g--) {
+ scavenge_mut_once_list(&generations[g]);
+ evac_gen = g;
+ for (st = generations[g].n_steps-1; st >= 0; st--) {
+ scavenge(&generations[g].steps[st]);
+ }
+ }
- /* Get a free block for to-space. Extra blocks will be chained on
- * as necessary.
+ for (g = RtsFlags.GcFlags.generations-1; g > N; g--) {
+ scavenge_mutable_list(&generations[g]);
+ evac_gen = g;
+ for (st = generations[g].n_steps-1; st >= 0; st--) {
+ scavenge(&generations[g].steps[st]);
+ }
+ }
+ }
+
+ /* follow all the roots that the application knows about.
*/
- bd = allocBlock();
- bd->step = 1; /* step 1 identifies to-space */
- toHp = bd->start;
- toHpLim = toHp + BLOCK_SIZE_W;
- toHp_bd = bd;
- to_space = bd;
- blocks = 0;
-
- scan = toHp;
- scan_bd = bd;
-
- /* follow all the roots that the application knows about */
+ evac_gen = 0;
get_roots();
/* And don't forget to mark the TSO if we got here direct from
/* Mark the weak pointer list, and prepare to detect dead weak
* pointers.
*/
- markWeakList();
old_weak_ptr_list = weak_ptr_list;
weak_ptr_list = NULL;
weak_done = rtsFalse;
+ /* Mark the stable pointer table.
+ */
+ markStablePtrTable(major_gc);
+
#ifdef INTERPRETER
{
/* ToDo: To fix the caf leak, we need to make the commented out
* the CAF document.
*/
extern void markHugsObjects(void);
-#if 0
- /* ToDo: This (undefined) function should contain the scavenge
- * loop immediately below this block of code - but I'm not sure
- * enough of the details to do this myself.
- */
- scavengeEverything();
- /* revert dead CAFs and update enteredCAFs list */
- revertDeadCAFs();
-#endif
markHugsObjects();
-#if 0
- /* This will keep the CAFs and the attached BCOs alive
- * but the values will have been reverted
- */
- scavengeEverything();
-#endif
}
#endif
- /* Then scavenge all the objects we picked up on the first pass.
- * We may require multiple passes to find all the static objects,
- * large objects and normal objects.
+ /* -------------------------------------------------------------------------
+ * Repeatedly scavenge all the areas we know about until there's no
+ * more scavenging to be done.
*/
{
+ rtsBool flag;
loop:
- if (static_objects != END_OF_STATIC_LIST) {
+ flag = rtsFalse;
+
+ /* scavenge static objects */
+ if (major_gc && static_objects != END_OF_STATIC_LIST) {
scavenge_static();
}
- if (toHp_bd != scan_bd || scan < toHp) {
- scan = scavenge(scan);
- scan_bd = Bdescr(scan);
- goto loop;
- }
- if (new_large_objects != NULL) {
- scavenge_large();
- goto loop;
+
+ /* When scavenging the older generations: Objects may have been
+ * evacuated from generations <= N into older generations, and we
+ * need to scavenge these objects. We're going to try to ensure that
+ * any evacuations that occur move the objects into at least the
+ * same generation as the object being scavenged, otherwise we
+ * have to create new entries on the mutable list for the older
+ * generation.
+ */
+
+ /* scavenge each step in generations 0..maxgen */
+ {
+ int gen, st;
+ loop2:
+ for (gen = RtsFlags.GcFlags.generations-1; gen >= 0; gen--) {
+ for (st = generations[gen].n_steps-1; st >= 0 ; st--) {
+ if (gen == 0 && st == 0 && RtsFlags.GcFlags.generations > 1) {
+ continue;
+ }
+ step = &generations[gen].steps[st];
+ evac_gen = gen;
+ if (step->hp_bd != step->scan_bd || step->scan < step->hp) {
+ scavenge(step);
+ flag = rtsTrue;
+ goto loop2;
+ }
+ if (step->new_large_objects != NULL) {
+ scavenge_large(step);
+ flag = rtsTrue;
+ goto loop2;
+ }
+ }
+ }
}
+ if (flag) { goto loop; }
+
/* must be last... */
if (traverse_weak_ptr_list()) { /* returns rtsTrue if evaced something */
goto loop;
}
}
- /* tidy up the end of the to-space chain */
- toHp_bd->free = toHp;
- toHp_bd->link = NULL;
-
+ /* Final traversal of the weak pointer list (see comment by
+ * cleanUpWeakPtrList below).
+ */
+ cleanup_weak_ptr_list(&weak_ptr_list);
+
+ /* Now see which stable names are still alive.
+ */
+ gcStablePtrTable(major_gc);
+
/* revert dead CAFs and update enteredCAFs list */
- revertDeadCAFs();
-
- /* mark the garbage collected CAFs as dead */
-#ifdef DEBUG
- gcCAFs();
-#endif
+ revert_dead_CAFs();
- zeroStaticObjectList(scavenged_static_objects);
-
- /* approximate amount of live data (doesn't take into account slop
- * at end of each block). ToDo: this more accurately.
+ /* Set the maximum blocks for the oldest generation, based on twice
+ * the amount of live data now, adjusted to fit the maximum heap
+ * size if necessary.
+ *
+ * This is an approximation, since in the worst case we'll need
+ * twice the amount of live data plus whatever space the other
+ * generations need.
*/
- live = blocks * BLOCK_SIZE_W + ((lnat)toHp_bd->free -
- (lnat)toHp_bd->start) / sizeof(W_);
+ if (RtsFlags.GcFlags.generations > 1) {
+ if (major_gc) {
+ oldest_gen->max_blocks =
+ stg_max(oldest_gen->steps[0].to_blocks * RtsFlags.GcFlags.oldGenFactor,
+ RtsFlags.GcFlags.minOldGenSize);
+ if (oldest_gen->max_blocks > RtsFlags.GcFlags.maxHeapSize / 2) {
+ oldest_gen->max_blocks = RtsFlags.GcFlags.maxHeapSize / 2;
+ if (((int)oldest_gen->max_blocks -
+ (int)oldest_gen->steps[0].to_blocks) <
+ (RtsFlags.GcFlags.pcFreeHeap *
+ RtsFlags.GcFlags.maxHeapSize / 200)) {
+ heapOverflow();
+ }
+ }
+ }
+ }
- /* Free the to-space from the last GC, as it has now been collected.
- * we may be able to re-use these blocks in creating a new nursery,
- * below. If not, the blocks will probably be re-used for to-space
- * in the next GC.
+ /* run through all the generations/steps and tidy up
*/
- if (old_to_space != NULL) {
- freeChain(old_to_space);
+ copied = new_blocks * BLOCK_SIZE_W;
+ for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
+
+ if (g <= N) {
+ generations[g].collections++; /* for stats */
+ }
+
+ for (s = 0; s < generations[g].n_steps; s++) {
+ bdescr *next;
+ step = &generations[g].steps[s];
+
+ if (!(g == 0 && s == 0 && RtsFlags.GcFlags.generations > 1)) {
+ /* Tidy the end of the to-space chains */
+ step->hp_bd->free = step->hp;
+ step->hp_bd->link = NULL;
+ /* stats information: how much we copied */
+ if (g <= N) {
+ copied -= step->hp_bd->start + BLOCK_SIZE_W -
+ step->hp_bd->free;
+ }
+ }
+
+ /* for generations we collected... */
+ if (g <= N) {
+
+ collected += step->n_blocks * BLOCK_SIZE_W; /* for stats */
+
+ /* 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 (!(g == 0 && s == 0)) {
+ freeChain(step->blocks);
+ step->blocks = step->to_space;
+ step->n_blocks = step->to_blocks;
+ step->to_space = NULL;
+ step->to_blocks = 0;
+ for (bd = step->blocks; bd != NULL; bd = bd->link) {
+ bd->evacuated = 0; /* now from-space */
+ }
+ }
+
+ /* LARGE OBJECTS. The current live large objects are chained on
+ * scavenged_large, having been moved during garbage
+ * collection from large_objects. Any objects left on
+ * large_objects list are therefore dead, so we free them here.
+ */
+ for (bd = step->large_objects; bd != NULL; bd = next) {
+ next = bd->link;
+ freeGroup(bd);
+ bd = next;
+ }
+ for (bd = step->scavenged_large_objects; bd != NULL; bd = bd->link) {
+ bd->evacuated = 0;
+ }
+ step->large_objects = step->scavenged_large_objects;
+
+ /* Set the maximum blocks for this generation, interpolating
+ * between the maximum size of the oldest and youngest
+ * generations.
+ *
+ * max_blocks = oldgen_max_blocks * G
+ * ----------------------
+ * oldest_gen
+ */
+ if (g != 0) {
+#if 0
+ generations[g].max_blocks = (oldest_gen->max_blocks * g)
+ / (RtsFlags.GcFlags.generations-1);
+#endif
+ generations[g].max_blocks = oldest_gen->max_blocks;
+ }
+
+ /* for older generations... */
+ } else {
+
+ /* For older generations, we need to append the
+ * scavenged_large_object list (i.e. large objects that have been
+ * promoted during this GC) to the large_object list for that step.
+ */
+ for (bd = step->scavenged_large_objects; bd; bd = next) {
+ next = bd->link;
+ bd->evacuated = 0;
+ dbl_link_onto(bd, &step->large_objects);
+ }
+
+ /* add the new blocks we promoted during this GC */
+ step->n_blocks += step->to_blocks;
+ }
+ }
}
- old_to_space = to_space;
- old_to_space_blocks = blocks;
+
+ /* Guess the amount of live data for stats. */
+ live = calcLive();
/* Free the small objects allocated via allocate(), since this will
- * all have been copied into to-space now.
+ * all have been copied into G0S1 now.
*/
if (small_alloc_list != NULL) {
freeChain(small_alloc_list);
}
small_alloc_list = NULL;
alloc_blocks = 0;
- alloc_blocks_lim = stg_max(blocks,RtsFlags.GcFlags.minAllocAreaSize);
+ alloc_Hp = NULL;
+ alloc_HpLim = NULL;
+ alloc_blocks_lim = RtsFlags.GcFlags.minAllocAreaSize;
- /* LARGE OBJECTS. The current live large objects are chained on
- * scavenged_large_objects, having been moved during garbage
- * collection from large_alloc_list. Any objects left on
- * large_alloc list are therefore dead, so we free them here.
+ /* Two-space collector:
+ * Free the old to-space, and estimate the amount of live data.
*/
- {
- bdescr *bd, *next;
- bd = large_alloc_list;
- while (bd != NULL) {
- next = bd->link;
- freeGroup(bd);
- bd = next;
+ if (RtsFlags.GcFlags.generations == 1) {
+ nat blocks;
+
+ if (old_to_space != NULL) {
+ freeChain(old_to_space);
+ }
+ for (bd = g0s0->to_space; bd != NULL; bd = bd->link) {
+ bd->evacuated = 0; /* now from-space */
}
- large_alloc_list = scavenged_large_objects;
- }
+ /* For a two-space collector, we need to resize the nursery. */
+
+ /* set up a new nursery. Allocate a nursery size based on a
+ * function of the amount of live data (currently a factor of 2,
+ * should be configurable (ToDo)). Use the blocks from the old
+ * nursery if possible, freeing up any left over blocks.
+ *
+ * If we get near the maximum heap size, then adjust our nursery
+ * size accordingly. If the nursery is the same size as the live
+ * data (L), then we need 3L bytes. We can reduce the size of the
+ * nursery to bring the required memory down near 2L bytes.
+ *
+ * A normal 2-space collector would need 4L bytes to give the same
+ * performance we get from 3L bytes, reducing to the same
+ * performance at 2L bytes.
+ */
+ blocks = g0s0->to_blocks;
- /* check sanity after GC */
- IF_DEBUG(sanity, checkHeap(to_space,1));
- /*IF_DEBUG(sanity, checkTSO(MainTSO,1)); */
- IF_DEBUG(sanity, checkFreeListSanity());
+ if ( blocks * RtsFlags.GcFlags.oldGenFactor * 2 >
+ RtsFlags.GcFlags.maxHeapSize ) {
+ int adjusted_blocks; /* signed on purpose */
+ int pc_free;
+
+ adjusted_blocks = (RtsFlags.GcFlags.maxHeapSize - 2 * blocks);
+ IF_DEBUG(gc, fprintf(stderr, "Near maximum heap size of 0x%x blocks, blocks = %d, adjusted to %d\n", RtsFlags.GcFlags.maxHeapSize, blocks, adjusted_blocks));
+ pc_free = adjusted_blocks * 100 / RtsFlags.GcFlags.maxHeapSize;
+ if (pc_free < RtsFlags.GcFlags.pcFreeHeap) /* might even be < 0 */ {
+ heapOverflow();
+ }
+ blocks = adjusted_blocks;
+
+ } else {
+ blocks *= RtsFlags.GcFlags.oldGenFactor;
+ if (blocks < RtsFlags.GcFlags.minAllocAreaSize) {
+ blocks = RtsFlags.GcFlags.minAllocAreaSize;
+ }
+ }
+ resizeNursery(blocks);
+
+ } else {
+ /* Generational collector:
+ * If the user has given us a suggested heap size, adjust our
+ * allocation area to make best use of the memory available.
+ */
-#ifdef DEBUG
- /* symbol-table based profiling */
- heapCensus(to_space);
-#endif
+ if (RtsFlags.GcFlags.heapSizeSuggestion) {
+ int blocks;
+ nat needed = calcNeeded(); /* approx blocks needed at next GC */
- /* set up a new nursery. Allocate a nursery size based on a
- * function of the amount of live data (currently a factor of 2,
- * should be configurable (ToDo)). Use the blocks from the old
- * nursery if possible, freeing up any left over blocks.
- *
- * If we get near the maximum heap size, then adjust our nursery
- * size accordingly. If the nursery is the same size as the live
- * data (L), then we need 3L bytes. We can reduce the size of the
- * nursery to bring the required memory down near 2L bytes.
- *
- * A normal 2-space collector would need 4L bytes to give the same
- * performance we get from 3L bytes, reducing to the same
- * performance at 2L bytes.
- */
- if ( blocks * 4 > RtsFlags.GcFlags.maxHeapSize ) {
- int adjusted_blocks; /* signed on purpose */
- int pc_free;
-
- adjusted_blocks = (RtsFlags.GcFlags.maxHeapSize - 2 * blocks);
- IF_DEBUG(gc, fprintf(stderr, "Near maximum heap size of 0x%x blocks, blocks = %d, adjusted to %d\n", RtsFlags.GcFlags.maxHeapSize, blocks, adjusted_blocks));
- pc_free = adjusted_blocks * 100 / RtsFlags.GcFlags.maxHeapSize;
- if (pc_free < RtsFlags.GcFlags.pcFreeHeap) /* might even be < 0 */ {
- heapOverflow();
- }
- blocks = adjusted_blocks;
+ /* Guess how much will be live in generation 0 step 0 next time.
+ * A good approximation is the obtained by finding the
+ * percentage of g0s0 that was live at the last minor GC.
+ */
+ if (N == 0) {
+ g0s0_pcnt_kept = (new_blocks * 100) / g0s0->n_blocks;
+ }
- } else {
- blocks *= 2;
- if (blocks < RtsFlags.GcFlags.minAllocAreaSize) {
- blocks = RtsFlags.GcFlags.minAllocAreaSize;
+ /* Estimate a size for the allocation area based on the
+ * information available. We might end up going slightly under
+ * or over the suggested heap size, but we should be pretty
+ * close on average.
+ *
+ * Formula: suggested - needed
+ * ----------------------------
+ * 1 + g0s0_pcnt_kept/100
+ *
+ * where 'needed' is the amount of memory needed at the next
+ * collection for collecting all steps except g0s0.
+ */
+ blocks =
+ (((int)RtsFlags.GcFlags.heapSizeSuggestion - (int)needed) * 100) /
+ (100 + (int)g0s0_pcnt_kept);
+
+ if (blocks < (int)RtsFlags.GcFlags.minAllocAreaSize) {
+ blocks = RtsFlags.GcFlags.minAllocAreaSize;
+ }
+
+ resizeNursery((nat)blocks);
}
}
+
+ /* mark the garbage collected CAFs as dead */
+#ifdef DEBUG
+ if (major_gc) { gcCAFs(); }
+#endif
- if (nursery_blocks < blocks) {
- IF_DEBUG(gc, fprintf(stderr, "Increasing size of nursery to %d blocks\n",
- blocks));
- nursery = allocNursery(nursery,blocks-nursery_blocks);
- } else {
- bdescr *next_bd = nursery;
-
- IF_DEBUG(gc, fprintf(stderr, "Decreasing size of nursery to %d blocks\n",
- blocks));
- for (bd = nursery; nursery_blocks > blocks; nursery_blocks--) {
- next_bd = bd->link;
- freeGroup(bd);
- bd = next_bd;
- }
- nursery = bd;
+ /* zero the scavenged static object list */
+ if (major_gc) {
+ zero_static_object_list(scavenged_static_objects);
}
-
- current_nursery = nursery;
- nursery_blocks = blocks;
- /* set the step number for each block in the nursery to zero */
- for (bd = nursery; bd != NULL; bd = bd->link) {
- bd->step = 0;
+ /* Reset the nursery
+ */
+ for (bd = g0s0->blocks; bd; bd = bd->link) {
bd->free = bd->start;
+ ASSERT(bd->gen == g0);
+ ASSERT(bd->step == g0s0);
+ IF_DEBUG(sanity,memset(bd->start, 0xaa, BLOCK_SIZE));
}
- for (bd = to_space; bd != NULL; bd = bd->link) {
- bd->step = 0;
- }
- for (bd = large_alloc_list; bd != NULL; bd = bd->link) {
- bd->step = 0;
- }
+ current_nursery = g0s0->blocks;
+
+ /* start any pending finalizers */
+ scheduleFinalizers(old_weak_ptr_list);
+
+ /* check sanity after GC */
+ IF_DEBUG(sanity, checkSanity(N));
+
+ /* extra GC trace info */
+ IF_DEBUG(gc, stat_describe_gens());
#ifdef DEBUG
- /* check that we really have the right number of blocks in the
- * nursery, or things could really get screwed up.
- */
- {
- nat i = 0;
- for (bd = nursery; bd != NULL; bd = bd->link) {
- ASSERT(bd->free == bd->start);
- ASSERT(bd->step == 0);
- i++;
- }
- ASSERT(i == nursery_blocks);
- }
+ /* symbol-table based profiling */
+ /* heapCensus(to_space); */ /* ToDo */
#endif
- /* start any pending finalisers */
- scheduleFinalisers(old_weak_ptr_list);
-
/* restore enclosing cost centre */
#ifdef PROFILING
CCCS = prev_CCS;
#endif
+ /* check for memory leaks if sanity checking is on */
+ IF_DEBUG(sanity, memInventory());
+
/* ok, GC over: tell the stats department what happened. */
- stat_endGC(allocated,
- (old_nursery_blocks + old_live_blocks) * BLOCK_SIZE_W,
- live, "");
+ stat_endGC(allocated, collected, live, copied, N);
}
/* -----------------------------------------------------------------------------
pointer code decide which weak pointers are dead - if there are no
new live weak pointers, then all the currently unreachable ones are
dead.
+
+ For generational GC: we just don't try to finalize weak pointers in
+ older generations than the one we're collecting. This could
+ probably be optimised by keeping per-generation lists of weak
+ pointers, but for a few weak pointers this scheme will work.
-------------------------------------------------------------------------- */
static rtsBool
traverse_weak_ptr_list(void)
{
StgWeak *w, **last_w, *next_w;
- StgClosure *target;
- const StgInfoTable *info;
+ StgClosure *new;
rtsBool flag = rtsFalse;
if (weak_done) { return rtsFalse; }
+ /* doesn't matter where we evacuate values/finalizers to, since
+ * these pointers are treated as roots (iff the keys are alive).
+ */
+ evac_gen = 0;
+
last_w = &old_weak_ptr_list;
for (w = old_weak_ptr_list; w; w = next_w) {
- target = w->key;
- loop:
- info = get_itbl(target);
- switch (info->type) {
-
- case IND:
- case IND_STATIC:
- case IND_PERM:
- case IND_OLDGEN:
- case IND_OLDGEN_PERM:
- /* follow indirections */
- target = ((StgInd *)target)->indirectee;
- goto loop;
- case EVACUATED:
- /* If key is alive, evacuate value and finaliser and
- * place weak ptr on new weak ptr list.
- */
- IF_DEBUG(weak, fprintf(stderr,"Weak pointer still alive at %p\n", w));
- w->key = ((StgEvacuated *)target)->evacuee;
+ /* First, this weak pointer might have been evacuated. If so,
+ * remove the forwarding pointer from the weak_ptr_list.
+ */
+ if (get_itbl(w)->type == EVACUATED) {
+ w = (StgWeak *)((StgEvacuated *)w)->evacuee;
+ *last_w = w;
+ }
+
+ /* There might be a DEAD_WEAK on the list if finalizeWeak# was
+ * called on a live weak pointer object. Just remove it.
+ */
+ if (w->header.info == &DEAD_WEAK_info) {
+ next_w = ((StgDeadWeak *)w)->link;
+ *last_w = next_w;
+ continue;
+ }
+
+ ASSERT(get_itbl(w)->type == WEAK);
+
+ /* Now, check whether the key is reachable.
+ */
+ if ((new = isAlive(w->key))) {
+ w->key = new;
+ /* evacuate the value and finalizer */
w->value = evacuate(w->value);
- w->finaliser = evacuate(w->finaliser);
-
+ w->finalizer = evacuate(w->finalizer);
/* remove this weak ptr from the old_weak_ptr list */
*last_w = w->link;
-
/* and put it on the new weak ptr list */
next_w = w->link;
w->link = weak_ptr_list;
weak_ptr_list = w;
flag = rtsTrue;
- break;
-
- default: /* key is dead */
+ IF_DEBUG(weak, fprintf(stderr,"Weak pointer still alive at %p -> %p\n", w, w->key));
+ continue;
+ }
+ else {
last_w = &(w->link);
next_w = w->link;
- break;
+ continue;
}
}
/* If we didn't make any changes, then we can go round and kill all
* the dead weak pointers. The old_weak_ptr list is used as a list
- * of pending finalisers later on.
+ * of pending finalizers later on.
*/
if (flag == rtsFalse) {
+ cleanup_weak_ptr_list(&old_weak_ptr_list);
for (w = old_weak_ptr_list; w; w = w->link) {
- w->value = evacuate(w->value);
- w->finaliser = evacuate(w->finaliser);
+ w->finalizer = evacuate(w->finalizer);
}
weak_done = rtsTrue;
}
return rtsTrue;
}
-StgClosure *MarkRoot(StgClosure *root)
+/* -----------------------------------------------------------------------------
+ After GC, the live weak pointer list may have forwarding pointers
+ on it, because a weak pointer object was evacuated after being
+ moved to the live weak pointer list. We remove those forwarding
+ pointers here.
+
+ Also, we don't consider weak pointer objects to be reachable, but
+ we must nevertheless consider them to be "live" and retain them.
+ Therefore any weak pointer objects which haven't as yet been
+ evacuated need to be evacuated now.
+ -------------------------------------------------------------------------- */
+
+static void
+cleanup_weak_ptr_list ( StgWeak **list )
+{
+ StgWeak *w, **last_w;
+
+ last_w = list;
+ for (w = *list; w; w = w->link) {
+
+ if (get_itbl(w)->type == EVACUATED) {
+ w = (StgWeak *)((StgEvacuated *)w)->evacuee;
+ *last_w = w;
+ }
+
+ if (Bdescr((P_)w)->evacuated == 0) {
+ (StgClosure *)w = evacuate((StgClosure *)w);
+ *last_w = w;
+ }
+ last_w = &(w->link);
+ }
+}
+
+/* -----------------------------------------------------------------------------
+ isAlive determines whether the given closure is still alive (after
+ a garbage collection) or not. It returns the new address of the
+ closure if it is alive, or NULL otherwise.
+ -------------------------------------------------------------------------- */
+
+StgClosure *
+isAlive(StgClosure *p)
+{
+ StgInfoTable *info;
+
+ while (1) {
+
+ info = get_itbl(p);
+
+ /* ToDo: for static closures, check the static link field.
+ * Problem here is that we sometimes don't set the link field, eg.
+ * for static closures with an empty SRT or CONSTR_STATIC_NOCAFs.
+ */
+
+ /* ignore closures in generations that we're not collecting. */
+ if (LOOKS_LIKE_STATIC(p) || Bdescr((P_)p)->gen->no > N) {
+ return p;
+ }
+
+ switch (info->type) {
+
+ case IND:
+ case IND_STATIC:
+ case IND_PERM:
+ case IND_OLDGEN: /* rely on compatible layout with StgInd */
+ case IND_OLDGEN_PERM:
+ /* follow indirections */
+ p = ((StgInd *)p)->indirectee;
+ continue;
+
+ case EVACUATED:
+ /* alive! */
+ return ((StgEvacuated *)p)->evacuee;
+
+ default:
+ /* dead. */
+ return NULL;
+ }
+ }
+}
+
+StgClosure *
+MarkRoot(StgClosure *root)
{
- root = evacuate(root);
- return root;
+ return evacuate(root);
}
-static __inline__ StgClosure *copy(StgClosure *src, W_ size)
+static void addBlock(step *step)
+{
+ bdescr *bd = allocBlock();
+ bd->gen = step->gen;
+ bd->step = step;
+
+ if (step->gen->no <= N) {
+ bd->evacuated = 1;
+ } else {
+ bd->evacuated = 0;
+ }
+
+ step->hp_bd->free = step->hp;
+ step->hp_bd->link = bd;
+ step->hp = bd->start;
+ step->hpLim = step->hp + BLOCK_SIZE_W;
+ step->hp_bd = bd;
+ step->to_blocks++;
+ new_blocks++;
+}
+
+static __inline__ void
+upd_evacuee(StgClosure *p, StgClosure *dest)
+{
+ p->header.info = &EVACUATED_info;
+ ((StgEvacuated *)p)->evacuee = dest;
+}
+
+static __inline__ StgClosure *
+copy(StgClosure *src, nat size, step *step)
{
P_ to, from, dest;
- if (toHp + size >= toHpLim) {
- bdescr *bd = allocBlock();
- toHp_bd->free = toHp;
- toHp_bd->link = bd;
- bd->step = 1; /* step 1 identifies to-space */
- toHp = bd->start;
- toHpLim = toHp + BLOCK_SIZE_W;
- toHp_bd = bd;
- blocks++;
+ 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 (step->gen->no < evac_gen) {
+#ifdef NO_EAGER_PROMOTION
+ failed_to_evac = rtsTrue;
+#else
+ step = &generations[evac_gen].steps[0];
+#endif
+ }
+
+ /* chain a new block onto the to-space for the destination step if
+ * necessary.
+ */
+ if (step->hp + size >= step->hpLim) {
+ addBlock(step);
}
- dest = toHp;
- toHp += size;
- for(to = dest, from = (P_)src; size>0; --size) {
+ for(to = step->hp, from = (P_)src; size>0; --size) {
*to++ = *from++;
}
+
+ dest = step->hp;
+ step->hp = to;
+ upd_evacuee(src,(StgClosure *)dest);
return (StgClosure *)dest;
}
-static __inline__ void upd_evacuee(StgClosure *p, StgClosure *dest)
+/* 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 __inline__ StgClosure *
+copyPart(StgClosure *src, nat size_to_reserve, nat size_to_copy, step *step)
{
- StgEvacuated *q = (StgEvacuated *)p;
+ P_ dest, to, from;
+
+ TICK_GC_WORDS_COPIED(size_to_copy);
+ if (step->gen->no < evac_gen) {
+#ifdef NO_EAGER_PROMOTION
+ failed_to_evac = rtsTrue;
+#else
+ step = &generations[evac_gen].steps[0];
+#endif
+ }
- SET_INFO(q,&EVACUATED_info);
- q->evacuee = dest;
+ if (step->hp + size_to_reserve >= step->hpLim) {
+ addBlock(step);
+ }
+
+ for(to = step->hp, from = (P_)src; size_to_copy>0; --size_to_copy) {
+ *to++ = *from++;
+ }
+
+ dest = step->hp;
+ step->hp += size_to_reserve;
+ upd_evacuee(src,(StgClosure *)dest);
+ return (StgClosure *)dest;
}
/* -----------------------------------------------------------------------------
This just consists of removing the object from the (doubly-linked)
large_alloc_list, and linking it on to the (singly-linked)
new_large_objects list, from where it will be scavenged later.
+
+ Convention: bd->evacuated is /= 0 for a large object that has been
+ evacuated, or 0 otherwise.
-------------------------------------------------------------------------- */
-static inline void evacuate_large(StgPtr p)
+static inline void
+evacuate_large(StgPtr p, rtsBool mutable)
{
bdescr *bd = Bdescr(p);
+ step *step;
/* should point to the beginning of the block */
ASSERT(((W_)p & BLOCK_MASK) == 0);
/* already evacuated? */
- if (bd->step == 1) {
+ if (bd->evacuated) {
+ /* Don't forget to set the 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;
+ TICK_GC_FAILED_PROMOTION();
+ }
return;
}
- /* remove from large_alloc_list */
+ step = bd->step;
+ /* remove from large_object list */
if (bd->back) {
bd->back->link = bd->link;
} else { /* first object in the list */
- large_alloc_list = bd->link;
+ step->large_objects = bd->link;
}
if (bd->link) {
bd->link->back = bd->back;
}
- /* link it on to the evacuated large object list */
- bd->link = new_large_objects;
- new_large_objects = bd;
- bd->step = 1;
-}
+ /* link it on to the evacuated large object list of the destination step
+ */
+ step = bd->step->to;
+ if (step->gen->no < evac_gen) {
+#ifdef NO_EAGER_PROMOTION
+ failed_to_evac = rtsTrue;
+#else
+ step = &generations[evac_gen].steps[0];
+#endif
+ }
+
+ bd->step = step;
+ bd->gen = step->gen;
+ bd->link = step->new_large_objects;
+ step->new_large_objects = bd;
+ bd->evacuated = 1;
+
+ if (mutable) {
+ recordMutable((StgMutClosure *)p);
+ }
+}
+
+/* -----------------------------------------------------------------------------
+ Adding a MUT_CONS to an older generation.
+
+ This is necessary from time to time when we end up with an
+ old-to-new generation pointer in a non-mutable object. We defer
+ the promotion until the next GC.
+ -------------------------------------------------------------------------- */
+
+static StgClosure *
+mkMutCons(StgClosure *ptr, generation *gen)
+{
+ StgMutVar *q;
+ step *step;
+
+ step = &gen->steps[0];
+
+ /* chain a new block onto the to-space for the destination step if
+ * necessary.
+ */
+ if (step->hp + sizeofW(StgIndOldGen) >= step->hpLim) {
+ addBlock(step);
+ }
+
+ q = (StgMutVar *)step->hp;
+ step->hp += sizeofW(StgMutVar);
+
+ SET_HDR(q,&MUT_CONS_info,CCS_GC);
+ q->var = ptr;
+ recordOldToNewPtrs((StgMutClosure *)q);
+
+ return (StgClosure *)q;
+}
/* -----------------------------------------------------------------------------
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.
+
-------------------------------------------------------------------------- */
-static StgClosure *evacuate(StgClosure *q)
+
+static StgClosure *
+evacuate(StgClosure *q)
{
StgClosure *to;
+ bdescr *bd = NULL;
+ step *step;
const StgInfoTable *info;
loop:
+ if (HEAP_ALLOCED(q)) {
+ 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 make an IND_OLDGEN object.
+ */
+ if (bd->gen->no < evac_gen) {
+ /* nope */
+ failed_to_evac = rtsTrue;
+ TICK_GC_FAILED_PROMOTION();
+ }
+ return q;
+ }
+ step = bd->step->to;
+ }
+
/* make sure the info pointer is into text space */
ASSERT(q && (LOOKS_LIKE_GHC_INFO(GET_INFO(q))
|| IS_HUGS_CONSTR_INFO(GET_INFO(q))));
switch (info -> type) {
case BCO:
- to = copy(q,bco_sizeW(stgCast(StgBCO*,q)));
- upd_evacuee(q,to);
+ return copy(q,bco_sizeW(stgCast(StgBCO*,q)),step);
+
+ case MUT_VAR:
+ ASSERT(q->header.info != &MUT_CONS_info);
+ case MVAR:
+ to = copy(q,sizeW_fromITBL(info),step);
+ recordMutable((StgMutClosure *)to);
return to;
+ case FUN_1_0:
+ case FUN_0_1:
+ case CONSTR_1_0:
+ case CONSTR_0_1:
+ return copy(q,sizeofW(StgHeader)+1,step);
+
+ case THUNK_1_0: /* here because of MIN_UPD_SIZE */
+ case THUNK_0_1:
+ case THUNK_1_1:
+ case THUNK_0_2:
+ case THUNK_2_0:
+#ifdef NO_PROMOTE_THUNKS
+ if (bd->gen->no == 0 &&
+ bd->step->no != 0 &&
+ bd->step->no == bd->gen->n_steps-1) {
+ step = bd->step;
+ }
+#endif
+ return copy(q,sizeofW(StgHeader)+2,step);
+
+ case FUN_1_1:
+ case FUN_0_2:
+ case FUN_2_0:
+ case CONSTR_1_1:
+ case CONSTR_0_2:
+ case CONSTR_2_0:
+ return copy(q,sizeofW(StgHeader)+2,step);
+
case FUN:
case THUNK:
case CONSTR:
case CAF_ENTERED:
case WEAK:
case FOREIGN:
- case MUT_VAR:
- case MVAR:
- to = copy(q,sizeW_fromITBL(info));
- upd_evacuee(q,to);
- return to;
+ case STABLE_NAME:
+ return copy(q,sizeW_fromITBL(info),step);
case CAF_BLACKHOLE:
case BLACKHOLE:
- to = copy(q,BLACKHOLE_sizeW());
- upd_evacuee(q,to);
+ return copyPart(q,BLACKHOLE_sizeW(),sizeofW(StgHeader),step);
+
+ case BLACKHOLE_BQ:
+ to = copy(q,BLACKHOLE_sizeW(),step);
+ recordMutable((StgMutClosure *)to);
return to;
case THUNK_SELECTOR:
{
const StgInfoTable* selectee_info;
- StgClosure* selectee = stgCast(StgSelector*,q)->selectee;
+ StgClosure* selectee = ((StgSelector*)q)->selectee;
selector_loop:
selectee_info = get_itbl(selectee);
switch (selectee_info->type) {
case CONSTR:
+ case CONSTR_1_0:
+ case CONSTR_0_1:
+ case CONSTR_2_0:
+ case CONSTR_1_1:
+ case CONSTR_0_2:
case CONSTR_STATIC:
{
- StgNat32 offset = info->layout.selector_offset;
+ StgWord32 offset = info->layout.selector_offset;
/* check that the size is in range */
ASSERT(offset <
- (StgNat32)(selectee_info->layout.payload.ptrs +
+ (StgWord32)(selectee_info->layout.payload.ptrs +
selectee_info->layout.payload.nptrs));
/* perform the selection! */
* with the evacuation, just update the source address with
* a pointer to the (evacuated) constructor field.
*/
- if (IS_USER_PTR(q) && Bdescr((P_)q)->step == 1) {
- return q;
+ if (HEAP_ALLOCED(q)) {
+ bdescr *bd = Bdescr((P_)q);
+ if (bd->evacuated) {
+ if (bd->gen->no < evac_gen) {
+ failed_to_evac = rtsTrue;
+ TICK_GC_FAILED_PROMOTION();
+ }
+ return q;
+ }
}
/* otherwise, carry on and evacuate this constructor field,
goto selector_loop;
case THUNK:
+ case THUNK_1_0:
+ case THUNK_0_1:
+ case THUNK_2_0:
+ case THUNK_1_1:
+ case THUNK_0_2:
case THUNK_STATIC:
case THUNK_SELECTOR:
/* aargh - do recursively???? */
case CAF_UNENTERED:
case CAF_BLACKHOLE:
case BLACKHOLE:
+ case BLACKHOLE_BQ:
/* not evaluated yet */
break;
barf("evacuate: THUNK_SELECTOR: strange selectee");
}
}
- to = copy(q,THUNK_SELECTOR_sizeW());
- upd_evacuee(q,to);
- return to;
+ return copy(q,THUNK_SELECTOR_sizeW(),step);
case IND:
case IND_OLDGEN:
/* follow chains of indirections, don't evacuate them */
- q = stgCast(StgInd*,q)->indirectee;
+ q = ((StgInd*)q)->indirectee;
goto loop;
- case CONSTR_STATIC:
case THUNK_STATIC:
+ if (info->srt_len > 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_len > 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:
- /* don't want to evacuate these, but we do want to follow pointers
- * from SRTs - see scavenge_static.
- */
+ if (major_gc && IND_STATIC_LINK((StgClosure *)q) == NULL) {
+ IND_STATIC_LINK((StgClosure *)q) = static_objects;
+ static_objects = (StgClosure *)q;
+ }
+ return q;
- /* put the object on the static list, if necessary.
- */
- if (STATIC_LINK(info,(StgClosure *)q) == NULL) {
+ case CONSTR_STATIC:
+ if (major_gc && STATIC_LINK(info,(StgClosure *)q) == NULL) {
STATIC_LINK(info,(StgClosure *)q) = static_objects;
static_objects = (StgClosure *)q;
}
- /* fall through */
+ return q;
case CONSTR_INTLIKE:
case CONSTR_CHARLIKE:
case PAP:
/* these are special - the payload is a copy of a chunk of stack,
tagging and all. */
- to = copy(q,pap_sizeW(stgCast(StgPAP*,q)));
- upd_evacuee(q,to);
- return to;
+ return copy(q,pap_sizeW(stgCast(StgPAP*,q)),step);
case EVACUATED:
- /* Already evacuated, just return the forwarding address */
- return stgCast(StgEvacuated*,q)->evacuee;
+ /* 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.
+ */
+ if (evac_gen > 0) { /* optimisation */
+ StgClosure *p = ((StgEvacuated*)q)->evacuee;
+ if (Bdescr((P_)p)->gen->no < evac_gen) {
+ /* fprintf(stderr,"evac failed!\n");*/
+ failed_to_evac = rtsTrue;
+ TICK_GC_FAILED_PROMOTION();
+ }
+ }
+ return ((StgEvacuated*)q)->evacuee;
- case MUT_ARR_WORDS:
case ARR_WORDS:
- case MUT_ARR_PTRS:
- case MUT_ARR_PTRS_FROZEN:
- case ARR_PTRS:
{
nat size = arr_words_sizeW(stgCast(StgArrWords*,q));
if (size >= LARGE_OBJECT_THRESHOLD/sizeof(W_)) {
- evacuate_large((P_)q);
+ evacuate_large((P_)q, rtsFalse);
return q;
} else {
/* just copy the block */
- to = copy(q,size);
- upd_evacuee(q,to);
- return to;
+ return copy(q,size,step);
+ }
+ }
+
+ case MUT_ARR_PTRS:
+ case MUT_ARR_PTRS_FROZEN:
+ {
+ nat size = mut_arr_ptrs_sizeW(stgCast(StgMutArrPtrs*,q));
+
+ if (size >= LARGE_OBJECT_THRESHOLD/sizeof(W_)) {
+ evacuate_large((P_)q, info->type == MUT_ARR_PTRS);
+ to = q;
+ } else {
+ /* just copy the block */
+ to = copy(q,size,step);
+ if (info->type == MUT_ARR_PTRS) {
+ recordMutable((StgMutClosure *)to);
+ }
}
+ return to;
}
case TSO:
/* Large TSOs don't get moved, so no relocation is required.
*/
if (size >= LARGE_OBJECT_THRESHOLD/sizeof(W_)) {
- evacuate_large((P_)q);
+ evacuate_large((P_)q, rtsTrue);
return q;
/* To evacuate a small TSO, we need to relocate the update frame
* list it contains.
*/
} else {
- StgTSO *new_tso = (StgTSO *)copy((StgClosure *)tso,tso_sizeW(tso));
+ StgTSO *new_tso = (StgTSO *)copy((StgClosure *)tso,tso_sizeW(tso),step);
diff = (StgPtr)new_tso - (StgPtr)tso; /* In *words* */
new_tso->splim = (StgPtr)new_tso->splim + diff;
relocate_TSO(tso, new_tso);
- upd_evacuee(q,(StgClosure *)new_tso);
+
+ recordMutable((StgMutClosure *)new_tso);
return (StgClosure *)new_tso;
}
}
}
static inline void
-evacuate_srt(const StgInfoTable *info)
+scavenge_srt(const StgInfoTable *info)
{
StgClosure **srt, **srt_end;
srt = stgCast(StgClosure **,info->srt);
srt_end = srt + info->srt_len;
for (; srt < srt_end; srt++) {
- evacuate(*srt);
+ /* 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)
+ reference to the DLL closure in the table by first adding one to it.
+ We check for this here, and undo the addition before evacuating it.
+
+ If the SRT entry hasn't got bit 0 set, the SRT entry points to a
+ closure that's fixed at link-time, and no extra magic is required.
+ */
+#ifdef HAVE_WIN32_DLL_SUPPORT
+ if ( stgCast(unsigned long,*srt) & 0x1 ) {
+ evacuate(*stgCast(StgClosure**,(stgCast(unsigned long, *srt) & ~0x1)));
+ } else {
+ evacuate(*srt);
+ }
+#else
+ evacuate(*srt);
+#endif
}
}
-static StgPtr
-scavenge(StgPtr to_scan)
+/* -----------------------------------------------------------------------------
+ Scavenge a given step until there are no more objects in this step
+ to scavenge.
+
+ evac_gen is set by the caller to be either zero (for a step in a
+ generation < N) or G where G is the generation of the step being
+ scavenged.
+
+ We sometimes temporarily change evac_gen back to zero if we're
+ scavenging a mutable object where early promotion isn't such a good
+ idea.
+ -------------------------------------------------------------------------- */
+
+
+static void
+scavenge(step *step)
{
- StgPtr p;
+ StgPtr p, q;
const StgInfoTable *info;
bdescr *bd;
+ nat saved_evac_gen = evac_gen; /* used for temporarily changing evac_gen */
- p = to_scan;
- bd = Bdescr((P_)p);
+ p = step->scan;
+ bd = step->scan_bd;
+
+ failed_to_evac = rtsFalse;
/* scavenge phase - standard breadth-first scavenging of the
* evacuated objects
*/
- while (bd != toHp_bd || p < toHp) {
+ while (bd != step->hp_bd || p < step->hp) {
/* If we're at the end of this block, move on to the next block */
- if (bd != toHp_bd && p == bd->free) {
+ if (bd != step->hp_bd && p == bd->free) {
bd = bd->link;
p = bd->start;
continue;
}
+ q = p; /* save ptr to object */
+
ASSERT(p && (LOOKS_LIKE_GHC_INFO(GET_INFO((StgClosure *)p))
|| IS_HUGS_CONSTR_INFO(GET_INFO((StgClosure *)p))));
bcoConstCPtr(bco,i) = evacuate(bcoConstCPtr(bco,i));
}
p += bco_sizeW(bco);
- continue;
+ break;
+ }
+
+ case MVAR:
+ /* treat MVars specially, because we don't want to evacuate the
+ * mut_link field in the middle of the closure.
+ */
+ {
+ StgMVar *mvar = ((StgMVar *)p);
+ evac_gen = 0;
+ (StgClosure *)mvar->head = evacuate((StgClosure *)mvar->head);
+ (StgClosure *)mvar->tail = evacuate((StgClosure *)mvar->tail);
+ (StgClosure *)mvar->value = evacuate((StgClosure *)mvar->value);
+ p += sizeofW(StgMVar);
+ evac_gen = saved_evac_gen;
+ break;
}
+ case THUNK_2_0:
+ case FUN_2_0:
+ scavenge_srt(info);
+ case CONSTR_2_0:
+ ((StgClosure *)p)->payload[1] = evacuate(((StgClosure *)p)->payload[1]);
+ ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]);
+ p += sizeofW(StgHeader) + 2;
+ break;
+
+ case THUNK_1_0:
+ scavenge_srt(info);
+ ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]);
+ p += sizeofW(StgHeader) + 2; /* MIN_UPD_SIZE */
+ break;
+
+ case FUN_1_0:
+ scavenge_srt(info);
+ case CONSTR_1_0:
+ ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]);
+ p += sizeofW(StgHeader) + 1;
+ break;
+
+ case THUNK_0_1:
+ scavenge_srt(info);
+ p += sizeofW(StgHeader) + 2; /* MIN_UPD_SIZE */
+ break;
+
+ case FUN_0_1:
+ scavenge_srt(info);
+ case CONSTR_0_1:
+ p += sizeofW(StgHeader) + 1;
+ break;
+
+ case THUNK_0_2:
+ case FUN_0_2:
+ scavenge_srt(info);
+ case CONSTR_0_2:
+ p += sizeofW(StgHeader) + 2;
+ break;
+
+ case THUNK_1_1:
+ case FUN_1_1:
+ scavenge_srt(info);
+ case CONSTR_1_1:
+ ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]);
+ p += sizeofW(StgHeader) + 2;
+ break;
+
case FUN:
case THUNK:
- evacuate_srt(info);
+ scavenge_srt(info);
/* fall through */
case CONSTR:
case WEAK:
case FOREIGN:
- case MVAR:
- case MUT_VAR:
+ case STABLE_NAME:
case IND_PERM:
case IND_OLDGEN_PERM:
case CAF_UNENTERED:
- case CAF_ENTERED:
{
StgPtr end;
(StgClosure *)*p = evacuate((StgClosure *)*p);
}
p += info->layout.payload.nptrs;
- continue;
+ break;
}
+ case CAF_ENTERED:
+ {
+ StgCAF *caf = (StgCAF *)p;
+
+ caf->body = evacuate(caf->body);
+ caf->value = evacuate(caf->value);
+ if (failed_to_evac) {
+ failed_to_evac = rtsFalse;
+ recordOldToNewPtrs((StgMutClosure *)p);
+ }
+ p += sizeofW(StgCAF);
+ break;
+ }
+
+ case MUT_VAR:
+ /* ignore MUT_CONSs */
+ if (((StgMutVar *)p)->header.info != &MUT_CONS_info) {
+ evac_gen = 0;
+ ((StgMutVar *)p)->var = evacuate(((StgMutVar *)p)->var);
+ evac_gen = saved_evac_gen;
+ }
+ p += sizeofW(StgMutVar);
+ break;
+
case CAF_BLACKHOLE:
case BLACKHOLE:
+ p += BLACKHOLE_sizeW();
+ break;
+
+ case BLACKHOLE_BQ:
{
- StgBlackHole *bh = (StgBlackHole *)p;
+ StgBlockingQueue *bh = (StgBlockingQueue *)p;
(StgClosure *)bh->blocking_queue =
evacuate((StgClosure *)bh->blocking_queue);
+ if (failed_to_evac) {
+ failed_to_evac = rtsFalse;
+ recordMutable((StgMutClosure *)bh);
+ }
p += BLACKHOLE_sizeW();
- continue;
+ break;
}
case THUNK_SELECTOR:
StgSelector *s = (StgSelector *)p;
s->selectee = evacuate(s->selectee);
p += THUNK_SELECTOR_sizeW();
- continue;
+ break;
}
case IND:
pap->fun = evacuate(pap->fun);
scavenge_stack((P_)pap->payload, (P_)pap->payload + pap->n_args);
p += pap_sizeW(pap);
- continue;
+ break;
}
case ARR_WORDS:
- case MUT_ARR_WORDS:
/* nothing to follow */
p += arr_words_sizeW(stgCast(StgArrWords*,p));
- continue;
+ break;
- case ARR_PTRS:
case MUT_ARR_PTRS:
- case MUT_ARR_PTRS_FROZEN:
/* follow everything */
{
StgPtr next;
- next = p + arr_ptrs_sizeW(stgCast(StgArrPtrs*,p));
- for (p = (P_)((StgArrPtrs *)p)->payload; p < next; p++) {
+ evac_gen = 0; /* repeatedly mutable */
+ next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p);
+ for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) {
(StgClosure *)*p = evacuate((StgClosure *)*p);
}
- continue;
+ evac_gen = saved_evac_gen;
+ break;
+ }
+
+ case MUT_ARR_PTRS_FROZEN:
+ /* follow everything */
+ {
+ StgPtr start = p, next;
+
+ next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p);
+ for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) {
+ (StgClosure *)*p = evacuate((StgClosure *)*p);
+ }
+ if (failed_to_evac) {
+ /* we can do this easier... */
+ recordMutable((StgMutClosure *)start);
+ failed_to_evac = rtsFalse;
+ }
+ break;
}
case TSO:
StgTSO *tso;
tso = (StgTSO *)p;
+ evac_gen = 0;
/* chase the link field for any TSOs on the same queue */
(StgClosure *)tso->link = evacuate((StgClosure *)tso->link);
/* scavenge this thread's stack */
scavenge_stack(tso->sp, &(tso->stack[tso->stack_size]));
+ evac_gen = saved_evac_gen;
p += tso_sizeW(tso);
- continue;
+ break;
}
case BLOCKED_FETCH:
default:
barf("scavenge");
}
+
+ /* If we didn't manage to promote all the objects pointed to by
+ * the current object, then we have to designate this object as
+ * mutable (because it contains old-to-new generation pointers).
+ */
+ if (failed_to_evac) {
+ mkMutCons((StgClosure *)q, &generations[evac_gen]);
+ failed_to_evac = rtsFalse;
+ }
}
- return (P_)p;
+
+ step->scan_bd = bd;
+ step->scan = p;
}
-/* scavenge_static is the scavenge code for a static closure.
- */
+/* -----------------------------------------------------------------------------
+ Scavenge one object.
+
+ This is used for objects that are temporarily marked as mutable
+ because they contain old-to-new generation pointers. Only certain
+ objects can have this property.
+ -------------------------------------------------------------------------- */
+static rtsBool
+scavenge_one(StgClosure *p)
+{
+ StgInfoTable *info;
+ rtsBool no_luck;
+
+ ASSERT(p && (LOOKS_LIKE_GHC_INFO(GET_INFO(p))
+ || IS_HUGS_CONSTR_INFO(GET_INFO(p))));
+
+ info = get_itbl(p);
+
+ switch (info -> type) {
+
+ 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:
+ case CONSTR:
+ case CONSTR_1_0:
+ case CONSTR_0_1:
+ case CONSTR_1_1:
+ case CONSTR_0_2:
+ case CONSTR_2_0:
+ case WEAK:
+ case FOREIGN:
+ case IND_PERM:
+ case IND_OLDGEN_PERM:
+ case CAF_UNENTERED:
+ {
+ StgPtr q, end;
+
+ end = (P_)p->payload + info->layout.payload.ptrs;
+ for (q = (P_)p->payload; q < end; q++) {
+ (StgClosure *)*q = evacuate((StgClosure *)*q);
+ }
+ break;
+ }
+
+ case CAF_BLACKHOLE:
+ case BLACKHOLE:
+ break;
+
+ case THUNK_SELECTOR:
+ {
+ StgSelector *s = (StgSelector *)p;
+ s->selectee = evacuate(s->selectee);
+ break;
+ }
+
+ case AP_UPD: /* same as PAPs */
+ case PAP:
+ /* Treat a PAP just like a section of stack, not forgetting to
+ * evacuate the function pointer too...
+ */
+ {
+ StgPAP* pap = (StgPAP *)p;
+
+ pap->fun = evacuate(pap->fun);
+ scavenge_stack((P_)pap->payload, (P_)pap->payload + pap->n_args);
+ break;
+ }
+
+ case IND_OLDGEN:
+ /* This might happen if for instance a MUT_CONS was pointing to a
+ * THUNK which has since been updated. The IND_OLDGEN will
+ * be on the mutable list anyway, so we don't need to do anything
+ * here.
+ */
+ break;
+
+ default:
+ barf("scavenge_one: strange object");
+ }
+
+ no_luck = failed_to_evac;
+ failed_to_evac = rtsFalse;
+ return (no_luck);
+}
+
+
+/* -----------------------------------------------------------------------------
+ Scavenging mutable lists.
+
+ We treat the mutable list of each generation > N (i.e. all the
+ generations older than the one being collected) as roots. We also
+ remove non-mutable objects from the mutable list at this point.
+ -------------------------------------------------------------------------- */
+
+static void
+scavenge_mut_once_list(generation *gen)
+{
+ StgInfoTable *info;
+ StgMutClosure *p, *next, *new_list;
+
+ p = gen->mut_once_list;
+ new_list = END_MUT_LIST;
+ next = p->mut_link;
+
+ evac_gen = gen->no;
+ failed_to_evac = rtsFalse;
+
+ for (; p != END_MUT_LIST; p = next, next = p->mut_link) {
+
+ /* make sure the info pointer is into text space */
+ ASSERT(p && (LOOKS_LIKE_GHC_INFO(GET_INFO(p))
+ || IS_HUGS_CONSTR_INFO(GET_INFO(p))));
+
+ info = get_itbl(p);
+ switch(info->type) {
+
+ case IND_OLDGEN:
+ case IND_OLDGEN_PERM:
+ case IND_STATIC:
+ /* Try to pull the indirectee into this generation, so we can
+ * remove the indirection from the mutable list.
+ */
+ ((StgIndOldGen *)p)->indirectee =
+ evacuate(((StgIndOldGen *)p)->indirectee);
+
+#if 0
+ /* Debugging code to print out the size of the thing we just
+ * promoted
+ */
+ {
+ StgPtr start = gen->steps[0].scan;
+ bdescr *start_bd = gen->steps[0].scan_bd;
+ nat size = 0;
+ scavenge(&gen->steps[0]);
+ if (start_bd != gen->steps[0].scan_bd) {
+ size += (P_)BLOCK_ROUND_UP(start) - start;
+ start_bd = start_bd->link;
+ while (start_bd != gen->steps[0].scan_bd) {
+ size += BLOCK_SIZE_W;
+ start_bd = start_bd->link;
+ }
+ size += gen->steps[0].scan -
+ (P_)BLOCK_ROUND_DOWN(gen->steps[0].scan);
+ } else {
+ size = gen->steps[0].scan - start;
+ }
+ fprintf(stderr,"evac IND_OLDGEN: %d bytes\n", size * sizeof(W_));
+ }
+#endif
+
+ /* failed_to_evac might happen if we've got more than two
+ * generations, we're collecting only generation 0, the
+ * indirection resides in generation 2 and the indirectee is
+ * in generation 1.
+ */
+ if (failed_to_evac) {
+ failed_to_evac = rtsFalse;
+ p->mut_link = new_list;
+ new_list = p;
+ } else {
+ /* the mut_link field of an IND_STATIC is overloaded as the
+ * static link field too (it just so happens that we don't need
+ * both at the same time), so we need to NULL it out when
+ * removing this object from the mutable list because the static
+ * link fields are all assumed to be NULL before doing a major
+ * collection.
+ */
+ p->mut_link = NULL;
+ }
+ continue;
+
+ case MUT_VAR:
+ /* MUT_CONS is a kind of MUT_VAR, except it that we try to remove
+ * it from the mutable list if possible by promoting whatever it
+ * points to.
+ */
+ ASSERT(p->header.info == &MUT_CONS_info);
+ if (scavenge_one(((StgMutVar *)p)->var) == rtsTrue) {
+ /* didn't manage to promote everything, so put the
+ * MUT_CONS back on the list.
+ */
+ p->mut_link = new_list;
+ new_list = p;
+ }
+ continue;
+
+ case CAF_ENTERED:
+ {
+ StgCAF *caf = (StgCAF *)p;
+ caf->body = evacuate(caf->body);
+ caf->value = evacuate(caf->value);
+ if (failed_to_evac) {
+ failed_to_evac = rtsFalse;
+ p->mut_link = new_list;
+ new_list = p;
+ }
+ }
+ continue;
+
+ case CAF_UNENTERED:
+ {
+ StgCAF *caf = (StgCAF *)p;
+ caf->body = evacuate(caf->body);
+ if (failed_to_evac) {
+ failed_to_evac = rtsFalse;
+ p->mut_link = new_list;
+ new_list = p;
+ }
+ }
+ continue;
+
+ default:
+ /* shouldn't have anything else on the mutables list */
+ barf("scavenge_mut_once_list: strange object?");
+ }
+ }
+
+ gen->mut_once_list = new_list;
+}
+
+
+static void
+scavenge_mutable_list(generation *gen)
+{
+ StgInfoTable *info;
+ StgMutClosure *p, *next;
+
+ p = gen->saved_mut_list;
+ next = p->mut_link;
+
+ evac_gen = 0;
+ failed_to_evac = rtsFalse;
+
+ for (; p != END_MUT_LIST; p = next, next = p->mut_link) {
+
+ /* make sure the info pointer is into text space */
+ ASSERT(p && (LOOKS_LIKE_GHC_INFO(GET_INFO(p))
+ || IS_HUGS_CONSTR_INFO(GET_INFO(p))));
+
+ info = get_itbl(p);
+ switch(info->type) {
+
+ case MUT_ARR_PTRS_FROZEN:
+ /* remove this guy from the mutable list, but follow the ptrs
+ * anyway (and make sure they get promoted to this gen).
+ */
+ {
+ StgPtr end, q;
+
+ end = (P_)p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p);
+ evac_gen = gen->no;
+ for (q = (P_)((StgMutArrPtrs *)p)->payload; q < end; q++) {
+ (StgClosure *)*q = evacuate((StgClosure *)*q);
+ }
+ evac_gen = 0;
+
+ if (failed_to_evac) {
+ failed_to_evac = rtsFalse;
+ p->mut_link = gen->mut_list;
+ gen->mut_list = p;
+ }
+ continue;
+ }
+
+ case MUT_ARR_PTRS:
+ /* follow everything */
+ p->mut_link = gen->mut_list;
+ gen->mut_list = p;
+ {
+ StgPtr end, q;
+
+ end = (P_)p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p);
+ for (q = (P_)((StgMutArrPtrs *)p)->payload; q < end; q++) {
+ (StgClosure *)*q = evacuate((StgClosure *)*q);
+ }
+ continue;
+ }
+
+ case MUT_VAR:
+ /* MUT_CONS is a kind of MUT_VAR, except that we try to remove
+ * it from the mutable list if possible by promoting whatever it
+ * points to.
+ */
+ ASSERT(p->header.info != &MUT_CONS_info);
+ ((StgMutVar *)p)->var = evacuate(((StgMutVar *)p)->var);
+ p->mut_link = gen->mut_list;
+ gen->mut_list = p;
+ continue;
+
+ case MVAR:
+ {
+ StgMVar *mvar = (StgMVar *)p;
+ (StgClosure *)mvar->head = evacuate((StgClosure *)mvar->head);
+ (StgClosure *)mvar->tail = evacuate((StgClosure *)mvar->tail);
+ (StgClosure *)mvar->value = evacuate((StgClosure *)mvar->value);
+ p->mut_link = gen->mut_list;
+ gen->mut_list = p;
+ continue;
+ }
+
+ case TSO:
+ /* follow ptrs and remove this from the mutable list */
+ {
+ StgTSO *tso = (StgTSO *)p;
+
+ /* Don't bother scavenging if this thread is dead
+ */
+ if (!(tso->whatNext == ThreadComplete ||
+ tso->whatNext == ThreadKilled)) {
+ /* Don't need to chase the link field for any TSOs on the
+ * same queue. Just scavenge this thread's stack
+ */
+ scavenge_stack(tso->sp, &(tso->stack[tso->stack_size]));
+ }
+
+ /* Don't take this TSO off the mutable list - it might still
+ * point to some younger objects (because we set evac_gen to 0
+ * above).
+ */
+ tso->mut_link = gen->mut_list;
+ gen->mut_list = (StgMutClosure *)tso;
+ continue;
+ }
+
+ case BLACKHOLE_BQ:
+ {
+ StgBlockingQueue *bh = (StgBlockingQueue *)p;
+ (StgClosure *)bh->blocking_queue =
+ evacuate((StgClosure *)bh->blocking_queue);
+ p->mut_link = gen->mut_list;
+ gen->mut_list = p;
+ continue;
+ }
+
+ default:
+ /* shouldn't have anything else on the mutables list */
+ barf("scavenge_mut_list: strange object?");
+ }
+ }
+}
static void
scavenge_static(void)
StgClosure* p = static_objects;
const StgInfoTable *info;
+ /* Always evacuate straight to the oldest generation for static
+ * objects */
+ evac_gen = oldest_gen->no;
+
/* keep going until we've scavenged all the objects on the linked
list... */
while (p != END_OF_STATIC_LIST) {
+ info = get_itbl(p);
+
/* make sure the info pointer is into text space */
- ASSERT(p && LOOKS_LIKE_GHC_INFO(GET_INFO(p)));
ASSERT(p && (LOOKS_LIKE_GHC_INFO(GET_INFO(p))
|| IS_HUGS_CONSTR_INFO(GET_INFO(p))));
-
- info = get_itbl(p);
-
+
/* 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;
scavenged_static_objects = p;
-
+
switch (info -> type) {
-
+
case IND_STATIC:
{
StgInd *ind = (StgInd *)p;
ind->indirectee = evacuate(ind->indirectee);
+
+ /* might fail to evacuate it, in which case we have to pop it
+ * back on the mutable list (and take it off the
+ * scavenged_static list because the static link and mut link
+ * pointers are one and the same).
+ */
+ if (failed_to_evac) {
+ failed_to_evac = rtsFalse;
+ scavenged_static_objects = STATIC_LINK(info,p);
+ ((StgMutClosure *)ind)->mut_link = oldest_gen->mut_once_list;
+ oldest_gen->mut_once_list = (StgMutClosure *)ind;
+ }
break;
}
case THUNK_STATIC:
case FUN_STATIC:
- evacuate_srt(info);
+ scavenge_srt(info);
/* fall through */
-
+
case CONSTR_STATIC:
{
StgPtr q, next;
barf("scavenge_static");
}
+ ASSERT(failed_to_evac == rtsFalse);
+
/* get the next static object from the list. Remeber, there might
* be more stuff on this list now that we've done some evacuating!
* (static_objects is a global)
{
StgPtr q;
const StgInfoTable* info;
- StgNat32 bitmap;
+ StgWord32 bitmap;
/*
* Each time around this loop, we are looking at a chunk of stack
/* Is q a pointer to a closure?
*/
- if (! LOOKS_LIKE_GHC_INFO(q)) {
+ if (! LOOKS_LIKE_GHC_INFO(q)) {
#ifdef DEBUG
- if (LOOKS_LIKE_STATIC(q)) { /* Is it a static closure? */
+ if ( 0 && LOOKS_LIKE_STATIC_CLOSURE(q) ) { /* Is it a static closure? */
ASSERT(closure_STATIC(stgCast(StgClosure*,q)));
- }
- /* otherwise, must be a pointer into the allocation space.
- */
+ }
+ /* otherwise, must be a pointer into the allocation space. */
#endif
(StgClosure *)*p = evacuate((StgClosure *)q);
goto follow_srt;
/* Specialised code for update frames, since they're so common.
- * We *know* the updatee points to a BLACKHOLE or CAF_BLACKHOLE,
- * so just inline the code to evacuate it here.
+ * We *know* the updatee points to a BLACKHOLE, CAF_BLACKHOLE,
+ * or BLACKHOLE_BQ, so just inline the code to evacuate it here.
*/
case UPDATE_FRAME:
{
StgUpdateFrame *frame = (StgUpdateFrame *)p;
StgClosure *to;
- StgClosureType type = get_itbl(frame->updatee)->type;
+ nat type = get_itbl(frame->updatee)->type;
+ p += sizeofW(StgUpdateFrame);
if (type == EVACUATED) {
frame->updatee = evacuate(frame->updatee);
- p += sizeofW(StgUpdateFrame);
continue;
} else {
- ASSERT(type == BLACKHOLE || type == CAF_BLACKHOLE);
- to = copy(frame->updatee, BLACKHOLE_sizeW());
- upd_evacuee(frame->updatee,to);
- frame->updatee = to;
- p += sizeofW(StgUpdateFrame);
- continue;
+ bdescr *bd = Bdescr((P_)frame->updatee);
+ step *step;
+ if (bd->gen->no > N) {
+ if (bd->gen->no < evac_gen) {
+ failed_to_evac = rtsTrue;
+ }
+ continue;
+ }
+
+ /* Don't promote blackholes */
+ step = bd->step;
+ if (!(step->gen->no == 0 &&
+ step->no != 0 &&
+ step->no == step->gen->n_steps-1)) {
+ step = step->to;
+ }
+
+ switch (type) {
+ case BLACKHOLE:
+ case CAF_BLACKHOLE:
+ to = copyPart(frame->updatee, BLACKHOLE_sizeW(),
+ sizeofW(StgHeader), step);
+ frame->updatee = to;
+ continue;
+ case BLACKHOLE_BQ:
+ to = copy(frame->updatee, BLACKHOLE_sizeW(), step);
+ frame->updatee = to;
+ recordMutable((StgMutClosure *)to);
+ continue;
+ default:
+ barf("scavenge_stack: UPDATE_FRAME updatee");
+ }
}
}
- /* small bitmap (< 32 entries) */
+ /* small bitmap (< 32 entries, or 64 on a 64-bit machine) */
case RET_BCO:
case RET_SMALL:
case RET_VEC_SMALL:
}
follow_srt:
- evacuate_srt(info);
+ scavenge_srt(info);
continue;
/* large bitmap (> 32 entries) */
case RET_BIG:
case RET_VEC_BIG:
{
+ StgPtr q;
StgLargeBitmap *large_bitmap;
nat i;
for (i=0; i<large_bitmap->size; i++) {
bitmap = large_bitmap->bitmap[i];
+ q = p + sizeof(W_) * 8;
while (bitmap != 0) {
if ((bitmap & 1) == 0) {
(StgClosure *)*p = evacuate((StgClosure *)*p);
p++;
bitmap = bitmap >> 1;
}
+ if (i+1 < large_bitmap->size) {
+ while (p < q) {
+ (StgClosure *)*p = evacuate((StgClosure *)*p);
+ p++;
+ }
+ }
}
/* and don't forget to follow the SRT */
barf("scavenge_stack: weird activation record found on stack.\n");
}
}
-}
+}
/*-----------------------------------------------------------------------------
scavenge the large object list.
+
+ evac_gen set by caller; similar games played with evac_gen as with
+ scavenge() - see comment at the top of scavenge(). Most large
+ objects are (repeatedly) mutable, so most of the time evac_gen will
+ be zero.
--------------------------------------------------------------------------- */
static void
-scavenge_large(void)
+scavenge_large(step *step)
{
bdescr *bd;
StgPtr p;
const StgInfoTable* info;
+ nat saved_evac_gen = evac_gen; /* used for temporarily changing evac_gen */
- bd = new_large_objects;
+ evac_gen = 0; /* most objects are mutable */
+ bd = step->new_large_objects;
- for (; bd != NULL; bd = new_large_objects) {
+ for (; bd != NULL; bd = step->new_large_objects) {
/* take this object *off* the large objects list and put it on
* the scavenged large objects list. This is so that we can
* treat new_large_objects as a stack and push new objects on
* the front when evacuating.
*/
- new_large_objects = bd->link;
- /* scavenged_large_objects is doubly linked */
- bd->link = scavenged_large_objects;
- bd->back = NULL;
- if (scavenged_large_objects) {
- scavenged_large_objects->back = bd;
- }
- scavenged_large_objects = bd;
+ step->new_large_objects = bd->link;
+ dbl_link_onto(bd, &step->scavenged_large_objects);
p = bd->start;
info = get_itbl(stgCast(StgClosure*,p));
/* only certain objects can be "large"... */
case ARR_WORDS:
- case MUT_ARR_WORDS:
/* nothing to follow */
continue;
- case ARR_PTRS:
case MUT_ARR_PTRS:
- case MUT_ARR_PTRS_FROZEN:
/* follow everything */
{
StgPtr next;
- next = p + arr_ptrs_sizeW(stgCast(StgArrPtrs*,p));
- for (p = (P_)((StgArrPtrs *)p)->payload; p < next; p++) {
+ next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p);
+ for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) {
+ (StgClosure *)*p = evacuate((StgClosure *)*p);
+ }
+ continue;
+ }
+
+ case MUT_ARR_PTRS_FROZEN:
+ /* follow everything */
+ {
+ StgPtr start = p, next;
+
+ evac_gen = saved_evac_gen; /* not really mutable */
+ next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p);
+ for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) {
(StgClosure *)*p = evacuate((StgClosure *)*p);
}
+ evac_gen = 0;
+ if (failed_to_evac) {
+ recordMutable((StgMutClosure *)start);
+ }
continue;
}
{
StgBCO* bco = stgCast(StgBCO*,p);
nat i;
+ evac_gen = saved_evac_gen;
for (i = 0; i < bco->n_ptrs; i++) {
bcoConstCPtr(bco,i) = evacuate(bcoConstCPtr(bco,i));
}
+ evac_gen = 0;
continue;
}
}
}
}
+
static void
-zeroStaticObjectList(StgClosure* first_static)
+zero_static_object_list(StgClosure* first_static)
{
StgClosure* p;
StgClosure* link;
}
}
+/* This function is only needed because we share the mutable link
+ * field with the static link field in an IND_STATIC, so we have to
+ * zero the mut_link field before doing a major GC, which needs the
+ * static link field.
+ *
+ * It doesn't do any harm to zero all the mutable link fields on the
+ * mutable list.
+ */
+static void
+zero_mutable_list( StgMutClosure *first )
+{
+ StgMutClosure *next, *c;
+
+ for (c = first; c != END_MUT_LIST; c = next) {
+ next = c->mut_link;
+ c->mut_link = NULL;
+ }
+}
+
/* -----------------------------------------------------------------------------
Reverting CAFs
-
-------------------------------------------------------------------------- */
void RevertCAFs(void)
{
- while (enteredCAFs != END_CAF_LIST) {
- StgCAF* caf = enteredCAFs;
- const StgInfoTable *info = get_itbl(caf);
-
- enteredCAFs = caf->link;
- ASSERT(get_itbl(caf)->type == CAF_ENTERED);
- SET_INFO(caf,&CAF_UNENTERED_info);
- caf->value = stgCast(StgClosure*,0xdeadbeef);
- caf->link = stgCast(StgCAF*,0xdeadbeef);
- }
+ while (enteredCAFs != END_CAF_LIST) {
+ StgCAF* caf = enteredCAFs;
+
+ enteredCAFs = caf->link;
+ ASSERT(get_itbl(caf)->type == CAF_ENTERED);
+ SET_INFO(caf,&CAF_UNENTERED_info);
+ caf->value = stgCast(StgClosure*,0xdeadbeef);
+ caf->link = stgCast(StgCAF*,0xdeadbeef);
+ }
+ enteredCAFs = END_CAF_LIST;
}
-void revertDeadCAFs(void)
+void revert_dead_CAFs(void)
{
StgCAF* caf = enteredCAFs;
enteredCAFs = END_CAF_LIST;
while (caf != END_CAF_LIST) {
- StgCAF* next = caf->link;
-
- switch(GET_INFO(caf)->type) {
- case EVACUATED:
- {
- /* This object has been evacuated, it must be live. */
- StgCAF* new = stgCast(StgCAF*,stgCast(StgEvacuated*,caf)->evacuee);
- new->link = enteredCAFs;
- enteredCAFs = new;
- break;
- }
- case CAF_ENTERED:
- {
- SET_INFO(caf,&CAF_UNENTERED_info);
- caf->value = stgCast(StgClosure*,0xdeadbeef);
- caf->link = stgCast(StgCAF*,0xdeadbeef);
- break;
- }
- default:
- barf("revertDeadCAFs: enteredCAFs list corrupted");
- }
- caf = next;
+ StgCAF *next, *new;
+ next = caf->link;
+ new = (StgCAF*)isAlive((StgClosure*)caf);
+ if (new) {
+ new->link = enteredCAFs;
+ enteredCAFs = new;
+ } else {
+ ASSERT(0);
+ SET_INFO(caf,&CAF_UNENTERED_info);
+ caf->value = (StgClosure*)0xdeadbeef;
+ caf->link = (StgCAF*)0xdeadbeef;
+ }
+ caf = next;
}
}
threadLazyBlackHole(StgTSO *tso)
{
StgUpdateFrame *update_frame;
- StgBlackHole *bh;
+ StgBlockingQueue *bh;
StgPtr stack_end;
stack_end = &tso->stack[tso->stack_size];
break;
case UPDATE_FRAME:
- bh = stgCast(StgBlackHole*,update_frame->updatee);
+ bh = (StgBlockingQueue *)update_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 == &BLACKHOLE_info) {
+ return;
+ }
- /* Don't for now: when we enter a CAF, we create a black hole on
- * the heap and make the update frame point to it. Thus the
- * above optimisation doesn't apply.
- */
- if (bh->header.info != &BLACKHOLE_info
- && bh->header.info != &CAF_BLACKHOLE_info) {
+ if (bh->header.info != &BLACKHOLE_BQ_info &&
+ bh->header.info != &CAF_BLACKHOLE_info) {
SET_INFO(bh,&BLACKHOLE_info);
- bh->blocking_queue = stgCast(StgTSO*,&END_TSO_QUEUE_closure);
}
update_frame = update_frame->link;
* added to the stack, rather than the way we see them in this
* walk. (It makes the next loop less confusing.)
*
- * Could stop if we find an update frame pointing to a black hole,
- * but see comment in threadLazyBlackHole().
+ * Stop if we find an update frame pointing to a black hole
+ * (see comment in threadLazyBlackHole()).
*/
next_frame = NULL;
frame->link = next_frame;
next_frame = frame;
frame = prev_frame;
+ if (get_itbl(frame)->type == UPDATE_FRAME
+ && frame->updatee->header.info == &BLACKHOLE_info) {
+ break;
+ }
}
/* Now, we're at the bottom. Frame points to the lowest update
* slower --SDM
*/
#if 0 /* do it properly... */
- if (GET_INFO(updatee_bypass) == BLACKHOLE_info
- || GET_INFO(updatee_bypass) == CAF_BLACKHOLE_info
- ) {
+ if (GET_INFO(updatee_bypass) == BLACKHOLE_BQ_info) {
/* Sigh. It has one. Don't lose those threads! */
- if (GET_INFO(updatee_keep) == BLACKHOLE_info
- || GET_INFO(updatee_keep) == CAF_BLACKHOLE_info
- ) {
+ if (GET_INFO(updatee_keep) == BLACKHOLE_BQ_info) {
/* Urgh. Two queues. Merge them. */
- P_ keep_tso = ((StgBlackHole *)updatee_keep)->blocking_queue;
+ P_ keep_tso = ((StgBlockingQueue *)updatee_keep)->blocking_queue;
while (keep_tso->link != END_TSO_QUEUE) {
keep_tso = keep_tso->link;
}
- keep_tso->link = ((StgBlackHole *)updatee_bypass)->blocking_queue;
+ keep_tso->link = ((StgBlockingQueue *)updatee_bypass)->blocking_queue;
} else {
/* For simplicity, just swap the BQ for the BH */
/* Do lazy black-holing.
*/
if (is_update_frame) {
- StgBlackHole *bh = (StgBlackHole *)frame->updatee;
- if (bh->header.info != &BLACKHOLE_info
- && bh->header.info != &CAF_BLACKHOLE_info
- ) {
+ StgBlockingQueue *bh = (StgBlockingQueue *)frame->updatee;
+ if (bh->header.info != &BLACKHOLE_BQ_info &&
+ bh->header.info != &CAF_BLACKHOLE_info) {
SET_INFO(bh,&BLACKHOLE_info);
- bh->blocking_queue = stgCast(StgTSO*,&END_TSO_QUEUE_closure);
}
}
projects / ghc-hetmet.git / blobdiff