/* -----------------------------------------------------------------------------
- * $Id: GC.c,v 1.129 2001/11/28 15:42:05 simonmar Exp $
*
- * (c) The GHC Team 1998-1999
+ * (c) The GHC Team 1998-2003
*
* Generational garbage collector
*
#include "Rts.h"
#include "RtsFlags.h"
#include "RtsUtils.h"
+#include "Apply.h"
+#include "OSThreads.h"
#include "Storage.h"
-#include "StoragePriv.h"
+#include "LdvProfile.h"
+#include "Updates.h"
#include "Stats.h"
#include "Schedule.h"
-#include "SchedAPI.h" // for ReverCAFs prototype
#include "Sanity.h"
#include "BlockAlloc.h"
#include "MBlock.h"
-#include "Main.h"
#include "ProfHeap.h"
#include "SchedAPI.h"
#include "Weak.h"
-#include "StablePriv.h"
#include "Prelude.h"
#include "ParTicky.h" // ToDo: move into Rts.h
#include "GCCompact.h"
+#include "RtsSignals.h"
+#include "STM.h"
#if defined(GRAN) || defined(PAR)
# include "GranSimRts.h"
# include "ParallelRts.h"
#endif
#include "RetainerProfile.h"
-#include "LdvProfile.h"
+
+#include <string.h>
+
+// Turn off inlining when debugging - it obfuscates things
+#ifdef DEBUG
+# undef STATIC_INLINE
+# define STATIC_INLINE static
+#endif
/* STATIC OBJECT LIST.
*
* 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
+static 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
*/
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 weak_done; // all done for this pass
+
+/* Which stage of processing various kinds of weak pointer are we at?
+ * (see traverse_weak_ptr_list() below for discussion).
+ */
+typedef enum { WeakPtrs, WeakThreads, WeakDone } WeakStage;
+static WeakStage weak_stage;
/* List of all threads during GC
*/
static StgTSO *old_all_threads;
-static StgTSO *resurrected_threads;
+StgTSO *resurrected_threads;
/* 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)
+/* Saved nursery (used for 2-space collector only)
*/
-bdescr *old_to_blocks;
-
+static bdescr *saved_nursery;
+static nat saved_n_blocks;
+
/* Data used for allocation area sizing.
*/
-lnat new_blocks; // blocks allocated during this GC
-lnat g0s0_pcnt_kept = 30; // percentage of g0s0 live at last minor GC
+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
*/
-lnat thunk_selector_depth = 0;
-#define MAX_THUNK_SELECTOR_DEPTH 256
+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
-------------------------------------------------------------------------- */
+static bdescr * gc_alloc_block ( step *stp );
static void mark_root ( StgClosure **root );
-static StgClosure * evacuate ( StgClosure *q );
+
+// Use a register argument for evacuate, if available.
+#if __GNUC__ >= 2
+#define REGPARM1 __attribute__((regparm(1)))
+#else
+#define REGPARM1
+#endif
+
+REGPARM1 static StgClosure * evacuate (StgClosure *q);
+
static void zero_static_object_list ( StgClosure* first_static );
-static void zero_mutable_list ( StgMutClosure *first );
static rtsBool traverse_weak_ptr_list ( void );
static void mark_weak_ptr_list ( StgWeak **list );
-static void scavenge ( step * );
-static void scavenge_mark_stack ( void );
-static void scavenge_stack ( StgPtr p, StgPtr stack_end );
-static rtsBool scavenge_one ( StgPtr p );
-static void scavenge_large ( step * );
-static void scavenge_static ( void );
-static void scavenge_mutable_list ( generation *g );
-static void scavenge_mut_once_list ( generation *g );
+static StgClosure * eval_thunk_selector ( nat field, StgSelector * p );
+
+
+static void scavenge ( step * );
+static void scavenge_mark_stack ( void );
+static void scavenge_stack ( StgPtr p, StgPtr stack_end );
+static rtsBool scavenge_one ( StgPtr p );
+static void scavenge_large ( step * );
+static void scavenge_static ( void );
+static void scavenge_mutable_list ( generation *g );
+
+static void scavenge_large_bitmap ( StgPtr p,
+ StgLargeBitmap *large_bitmap,
+ nat size );
#if 0 && defined(DEBUG)
static void gcCAFs ( void );
static bdescr *oldgen_scan_bd;
static StgPtr oldgen_scan;
-static inline rtsBool
+STATIC_INLINE rtsBool
mark_stack_empty(void)
{
return mark_sp == mark_stack;
}
-static inline rtsBool
+STATIC_INLINE rtsBool
mark_stack_full(void)
{
return mark_sp >= mark_splim;
}
-static inline void
+STATIC_INLINE void
reset_mark_stack(void)
{
mark_sp = mark_stack;
}
-static inline void
+STATIC_INLINE void
push_mark_stack(StgPtr p)
{
*mark_sp++ = p;
}
-static inline StgPtr
+STATIC_INLINE StgPtr
pop_mark_stack(void)
{
return *--mark_sp;
}
/* -----------------------------------------------------------------------------
+ Allocate a new to-space block in the given step.
+ -------------------------------------------------------------------------- */
+
+static bdescr *
+gc_alloc_block(step *stp)
+{
+ bdescr *bd = allocBlock();
+ bd->gen_no = stp->gen_no;
+ bd->step = stp;
+ bd->link = NULL;
+
+ // 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;
+ }
+
+ // Start a new to-space block, chain it on after the previous one.
+ if (stp->hp_bd != NULL) {
+ stp->hp_bd->free = stp->hp;
+ stp->hp_bd->link = bd;
+ }
+
+ stp->hp_bd = bd;
+ stp->hp = bd->start;
+ stp->hpLim = stp->hp + BLOCK_SIZE_W;
+
+ 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
- For garbage collecting generation N (and all younger generations):
+ Rough outline of the algorithm: 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.
+ mutable objects in all generations (mutable_list).
- 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.
+
+ + to-space of the step given by step->to, which is the next
+ highest step in this generation or the first step in the next
+ generation if this is the last step.
+
+ + to-space of generations[evac_gen]->steps[0], if evac_gen != 0.
+ When we evacuate an object we attempt to evacuate
+ everything it points to into the same generation - this is
+ achieved by setting evac_gen to the desired generation. If
+ we can't do this, then an entry in the mut list has to
+ be made for the cross-generation pointer.
+
+ + if the object is already in a generation > N, then leave
+ it alone.
- 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.
+ Locks held: all capabilities are held throughout GarbageCollect().
+
-------------------------------------------------------------------------- */
void
{
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;
#endif
#if defined(DEBUG) && defined(GRAN)
- IF_DEBUG(gc, belch("@@ Starting garbage collection at %ld (%lx)\n",
+ IF_DEBUG(gc, debugBelch("@@ Starting garbage collection at %ld (%lx)\n",
Now, Now));
#endif
+#if defined(RTS_USER_SIGNALS)
+ // block signals
+ blockUserSignals();
+#endif
+
+ // tell the STM to discard any cached closures its hoping to re-use
+ stmPreGCHook();
+
// 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;
- /* 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
+ /* 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;
+ 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.
- */
+ // 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;
+
+ // throw away the mutable list. Invariant: the mutable list
+ // always has at least one block; this means we can avoid a check for
+ // NULL in recordMutable().
+ 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++) {
continue;
}
- /* Get a free block for to-space. Extra blocks will be chained on
- * as necessary.
- */
- bd = allocBlock();
stp = &generations[g].steps[s];
ASSERT(stp->gen_no == g);
- ASSERT(stp->hp ? Bdescr(stp->hp)->step == stp : rtsTrue);
- bd->gen_no = g;
- bd->step = stp;
- bd->link = NULL;
- bd->flags = BF_EVACUATED; // it's a to-space block
- stp->hp = bd->start;
- stp->hpLim = stp->hp + BLOCK_SIZE_W;
- stp->hp_bd = bd;
- stp->to_blocks = bd;
- stp->n_to_blocks = 1;
+
+ // start a new to-space for this step.
+ 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->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;
stp->n_scavenged_large_blocks = 0;
- new_blocks++;
+
// mark the large objects as not evacuated yet
for (bd = stp->large_objects; bd; bd = bd->link) {
- bd->flags = BF_LARGE;
+ bd->flags &= ~BF_EVACUATED;
}
// for a compacted step, we need to allocate the bitmap
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((nat)BLOCK_ROUND_UP(bitmap_size)
+ bitmap_bdescr = allocGroup((lnat)BLOCK_ROUND_UP(bitmap_size)
/ BLOCK_SIZE);
stp->bitmap = bitmap_bdescr;
bitmap = bitmap_bdescr->start;
- IF_DEBUG(gc, belch("bitmap_size: %d, bitmap: %p",
+ IF_DEBUG(gc, debugBelch("bitmap_size: %d, bitmap: %p",
bitmap_size, bitmap););
// don't forget to fill it with zeros!
memset(bitmap, 0, bitmap_size);
- // for each block in this step, point to its bitmap from the
+ // 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);
+
+ // Also at this point we set the BF_COMPACTED flag
+ // for this block. The invariant is that
+ // BF_COMPACTED is always unset, except during GC
+ // when it is set on those blocks which will be
+ // compacted.
+ bd->flags |= BF_COMPACTED;
}
}
}
}
/* make sure the older generations have at least one block to
- * allocate into (this makes things easier for copy(), see below.
+ * 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++) {
stp = &generations[g].steps[s];
if (stp->hp_bd == NULL) {
ASSERT(stp->blocks == NULL);
- bd = allocBlock();
- bd->gen_no = g;
- bd->step = stp;
- bd->link = NULL;
- bd->flags = 0; // *not* a to-space block or a large object
- stp->hp = bd->start;
- stp->hpLim = stp->hp + BLOCK_SIZE_W;
- stp->hp_bd = bd;
+ bd = gc_alloc_block(stp);
stp->blocks = bd;
stp->n_blocks = 1;
- new_blocks++;
+ }
+ 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
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--) {
- IF_PAR_DEBUG(verbose,
- printMutOnceList(&generations[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]);
- }
+ generations[g].mut_list = allocBlock();
+ // mut_list always has at least one block.
}
for (g = RtsFlags.GcFlags.generations-1; g > N; g--) {
- IF_PAR_DEBUG(verbose,
- printMutableList(&generations[g]));
+ IF_PAR_DEBUG(verbose, printMutableList(&generations[g]));
scavenge_mutable_list(&generations[g]);
evac_gen = g;
for (st = generations[g].n_steps-1; st >= 0; st--) {
mark_weak_ptr_list(&weak_ptr_list);
old_weak_ptr_list = weak_ptr_list;
weak_ptr_list = NULL;
- weak_done = rtsFalse;
+ weak_stage = WeakPtrs;
/* The all_threads list is like the weak_ptr_list.
* See traverse_weak_ptr_list() for the details.
*/
markStablePtrTable(mark_root);
-#ifdef INTERPRETER
- {
- /* ToDo: To fix the caf leak, we need to make the commented out
- * parts of this code do something sensible - as described in
- * the CAF document.
- */
- extern void markHugsObjects(void);
- markHugsObjects();
- }
-#endif
-
/* -------------------------------------------------------------------------
* Repeatedly scavenge all the areas we know about until there's no
* more scavenging to be done.
if (flag) { goto loop; }
- // must be last...
+ // must be last... invariant is that everything is fully
+ // scavenged at this point.
if (traverse_weak_ptr_list()) { // returns rtsTrue if evaced something
goto loop;
}
}
+ /* 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
+ * GC by virtue of being on the all_threads list, we're just
+ * updating pointers here.
+ */
+ {
+ Task *task;
+ StgTSO *tso;
+ 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;
+ }
+ }
+ }
+
#if defined(PAR)
// Reconstruct the Global Address tables used in GUM
rebuildGAtables(major_gc);
for (s = 0; s < generations[g].n_steps; s++) {
stp = &generations[g].steps[s];
if (!(g == 0 && s == 0 && RtsFlags.GcFlags.generations > 1)) {
+ ASSERT(Bdescr(stp->hp) == stp->hp_bd);
stp->hp_bd->free = stp->hp;
- stp->hp_bd->link = NULL;
+ 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) {
generations[g].collections++; // for stats
}
+ // 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) {
+ 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++) {
bdescr *next;
stp = &generations[g].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) {
- bd->flags &= ~BF_EVACUATED; // now from-space
+ 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) {
+ 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->to_blocks;
+ 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
+ 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_large_blocks += stp->n_scavenged_large_blocks;
}
}
oldest_gen->steps[0].n_blocks >
(RtsFlags.GcFlags.compactThreshold * max) / 100))) {
oldest_gen->steps[0].is_compacted = 1;
-// fprintf(stderr,"compaction: on\n", live);
+// debugBelch("compaction: on\n", live);
} else {
oldest_gen->steps[0].is_compacted = 0;
-// fprintf(stderr,"compaction: off\n", live);
+// debugBelch("compaction: off\n", live);
}
// if we're going to go over the maximum heap size, reduce the
}
#if 0
- fprintf(stderr,"live: %d, min_alloc: %d, size : %d, max = %d\n", live,
+ debugBelch("live: %d, min_alloc: %d, size : %d, max = %d\n", live,
min_alloc, size, max);
#endif
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 >
int pc_free;
adjusted_blocks = (RtsFlags.GcFlags.maxHeapSize - 2 * blocks);
- IF_DEBUG(gc, belch("@@ Near maximum heap size of 0x%x blocks, blocks = %d, adjusted to %ld", RtsFlags.GcFlags.maxHeapSize, blocks, adjusted_blocks));
+ IF_DEBUG(gc, debugBelch("@@ Near maximum heap size of 0x%x blocks, blocks = %d, adjusted to %ld", 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 = RtsFlags.GcFlags.minAllocAreaSize;
}
}
- resizeNursery(blocks);
+ resizeNurseries(blocks);
} else {
/* Generational collector:
* percentage of g0s0 that was live at the last minor GC.
*/
if (N == 0) {
- g0s0_pcnt_kept = (new_blocks * 100) / g0s0->n_blocks;
+ g0s0_pcnt_kept = (new_blocks * 100) / countNurseryBlocks();
}
/* Estimate a size for the allocation area based on the
blocks = RtsFlags.GcFlags.minAllocAreaSize;
}
- resizeNursery((nat)blocks);
+ resizeNurseries((nat)blocks);
} else {
// we might have added extra large blocks to the nursery, so
// resize back to minAllocAreaSize again.
- resizeNursery(RtsFlags.GcFlags.minAllocAreaSize);
+ resizeNurseriesFixed(RtsFlags.GcFlags.minAllocAreaSize);
}
}
resetNurseries();
// 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_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();
}
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.
+
+ There are three distinct stages to processing weak pointers:
+
+ - weak_stage == WeakPtrs
+
+ We process all the weak pointers whos keys are alive (evacuate
+ their values and finalizers), and repeat until we can find no new
+ live keys. If no live keys are found in this pass, then we
+ evacuate the finalizers of all the dead weak pointers in order to
+ run them.
+
+ - weak_stage == WeakThreads
+
+ Now, we discover which *threads* are still alive. Pointers to
+ threads from the all_threads and main thread lists are the
+ weakest of all: a pointers from the finalizer of a dead weak
+ pointer can keep a thread alive. Any threads found to be unreachable
+ are evacuated and placed on the resurrected_threads list so we
+ can send them a signal later.
+
+ - weak_stage == WeakDone
+
+ No more evacuation is done.
+
-------------------------------------------------------------------------- */
static rtsBool
StgClosure *new;
rtsBool flag = rtsFalse;
- if (weak_done) { return rtsFalse; }
+ switch (weak_stage) {
- /* doesn't matter where we evacuate values/finalizers to, since
- * these pointers are treated as roots (iff the keys are alive).
- */
- evac_gen = 0;
+ case WeakDone:
+ return rtsFalse;
+
+ case WeakPtrs:
+ /* 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 != NULL; w = next_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 == &stg_DEAD_WEAK_info) {
+ next_w = ((StgDeadWeak *)w)->link;
+ *last_w = next_w;
+ continue;
+ }
+
+ switch (get_itbl(w)->type) {
- last_w = &old_weak_ptr_list;
- for (w = old_weak_ptr_list; w != NULL; w = next_w) {
+ case EVACUATED:
+ next_w = (StgWeak *)((StgEvacuated *)w)->evacuee;
+ *last_w = next_w;
+ continue;
- /* 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 == &stg_DEAD_WEAK_info) {
- next_w = ((StgDeadWeak *)w)->link;
- *last_w = next_w;
- continue;
- }
+ case WEAK:
+ /* Now, check whether the key is reachable.
+ */
+ new = isAlive(w->key);
+ if (new != NULL) {
+ w->key = new;
+ // evacuate the value and finalizer
+ w->value = evacuate(w->value);
+ 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;
+ IF_DEBUG(weak, debugBelch("Weak pointer still alive at %p -> %p",
+ w, w->key));
+ continue;
+ }
+ else {
+ last_w = &(w->link);
+ next_w = w->link;
+ continue;
+ }
- ASSERT(get_itbl(w)->type == WEAK);
+ default:
+ barf("traverse_weak_ptr_list: not WEAK");
+ }
+ }
+
+ /* 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 finalizers later on.
+ */
+ if (flag == rtsFalse) {
+ for (w = old_weak_ptr_list; w; w = w->link) {
+ w->finalizer = evacuate(w->finalizer);
+ }
- /* Now, check whether the key is reachable.
- */
- new = isAlive(w->key);
- if (new != NULL) {
- w->key = new;
- // evacuate the value and finalizer
- w->value = evacuate(w->value);
- 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;
- IF_DEBUG(weak, belch("Weak pointer still alive at %p -> %p", w, w->key));
- continue;
- }
- else {
- last_w = &(w->link);
- next_w = w->link;
- continue;
- }
- }
+ // Next, move to the WeakThreads stage after fully
+ // scavenging the finalizers we've just evacuated.
+ weak_stage = WeakThreads;
+ }
- /* Now deal with the all_threads list, which behaves somewhat like
- * the weak ptr list. If we discover any threads that are about to
- * become garbage, we wake them up and administer an exception.
- */
- {
- StgTSO *t, *tmp, *next, **prev;
+ return rtsTrue;
- prev = &old_all_threads;
- for (t = old_all_threads; t != END_TSO_QUEUE; t = next) {
+ case WeakThreads:
+ /* Now deal with the all_threads list, which behaves somewhat like
+ * the weak ptr list. If we discover any threads that are about to
+ * become garbage, we wake them up and administer an exception.
+ */
+ {
+ StgTSO *t, *tmp, *next, **prev;
+
+ prev = &old_all_threads;
+ for (t = old_all_threads; t != END_TSO_QUEUE; t = next) {
+
+ tmp = (StgTSO *)isAlive((StgClosure *)t);
+
+ if (tmp != NULL) {
+ t = tmp;
+ }
+
+ ASSERT(get_itbl(t)->type == TSO);
+ switch (t->what_next) {
+ case ThreadRelocated:
+ next = t->link;
+ *prev = next;
+ continue;
+ case ThreadKilled:
+ case ThreadComplete:
+ // finshed or died. The thread might still be alive, but we
+ // don't keep it on the all_threads list. Don't forget to
+ // stub out its global_link field.
+ next = t->global_link;
+ t->global_link = END_TSO_QUEUE;
+ *prev = next;
+ continue;
+ default:
+ ;
+ }
+
+ // 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;
+ }
+ }
- (StgClosure *)tmp = isAlive((StgClosure *)t);
-
- if (tmp != NULL) {
- t = tmp;
+ if (tmp == NULL) {
+ // not alive (yet): leave this thread on the
+ // old_all_threads list.
+ prev = &(t->global_link);
+ next = t->global_link;
+ }
+ else {
+ // alive: move this thread onto the all_threads list.
+ next = t->global_link;
+ t->global_link = all_threads;
+ all_threads = t;
+ *prev = next;
+ }
+ }
}
+
+ /* If we evacuated any threads, we need to go back to the scavenger.
+ */
+ if (flag) return rtsTrue;
- ASSERT(get_itbl(t)->type == TSO);
- switch (t->what_next) {
- case ThreadRelocated:
- next = t->link;
- *prev = next;
- continue;
- case ThreadKilled:
- case ThreadComplete:
- // finshed or died. The thread might still be alive, but we
- // don't keep it on the all_threads list. Don't forget to
- // stub out its global_link field.
- next = t->global_link;
- t->global_link = END_TSO_QUEUE;
- *prev = next;
- continue;
- default:
- ;
+ /* And resurrect any threads which were about to become garbage.
+ */
+ {
+ StgTSO *t, *tmp, *next;
+ for (t = old_all_threads; t != END_TSO_QUEUE; t = next) {
+ next = t->global_link;
+ tmp = (StgTSO *)evacuate((StgClosure *)t);
+ tmp->global_link = resurrected_threads;
+ resurrected_threads = tmp;
+ }
}
-
- if (tmp == NULL) {
- // not alive (yet): leave this thread on the old_all_threads list.
- prev = &(t->global_link);
- next = t->global_link;
- }
- else {
- // alive: move this thread onto the all_threads list.
- next = t->global_link;
- t->global_link = all_threads;
- all_threads = t;
- *prev = next;
+
+ /* 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);
+ }
}
- }
- }
- /* 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 finalizers later on.
- */
- if (flag == rtsFalse) {
- for (w = old_weak_ptr_list; w; w = w->link) {
- w->finalizer = evacuate(w->finalizer);
- }
-
- /* And resurrect any threads which were about to become garbage.
- */
- {
- StgTSO *t, *tmp, *next;
- for (t = old_all_threads; t != END_TSO_QUEUE; t = next) {
- next = t->global_link;
- (StgClosure *)tmp = evacuate((StgClosure *)t);
- tmp->global_link = resurrected_threads;
- resurrected_threads = tmp;
- }
- }
+ weak_stage = WeakDone; // *now* we're done,
+ return rtsTrue; // but one more round of scavenging, please
- weak_done = rtsTrue;
+ default:
+ barf("traverse_weak_ptr_list");
+ return rtsTrue;
}
- return rtsTrue;
}
/* -----------------------------------------------------------------------------
last_w = list;
for (w = *list; w; w = w->link) {
- (StgClosure *)w = evacuate((StgClosure *)w);
+ // w might be WEAK, EVACUATED, or DEAD_WEAK (actually CON_STATIC) here
+ ASSERT(w->header.info == &stg_DEAD_WEAK_info
+ || get_itbl(w)->type == WEAK || get_itbl(w)->type == EVACUATED);
+ w = (StgWeak *)evacuate((StgClosure *)w);
*last_w = w;
last_w = &(w->link);
}
while (1) {
+ ASSERT(LOOKS_LIKE_CLOSURE_PTR(p));
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 static closures
+ //
+ // 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.
+ //
+ if (!HEAP_ALLOCED(p)) {
+ return p;
+ }
- loop:
- bd = Bdescr((P_)p);
// ignore closures in generations that we're not collecting.
- if (LOOKS_LIKE_STATIC(p) || bd->gen_no > N) {
+ bd = Bdescr((P_)p);
+ if (bd->gen_no > N) {
+ return p;
+ }
+
+ // if it's a pointer into to-space, then we're done
+ if (bd->flags & BF_EVACUATED) {
return p;
}
- // large objects have an evacuated flag
+
+ // large objects use the evacuated flag
if (bd->flags & BF_LARGE) {
- if (bd->flags & BF_EVACUATED) {
- return p;
- } else {
- return NULL;
- }
+ return NULL;
}
+
// check the mark bit for compacted steps
- if (bd->step->is_compacted && is_marked((P_)p,bd)) {
+ if ((bd->flags & BF_COMPACTED) && is_marked((P_)p,bd)) {
return p;
}
case TSO:
if (((StgTSO *)p)->what_next == ThreadRelocated) {
p = (StgClosure *)((StgTSO *)p)->link;
- goto loop;
- }
+ continue;
+ }
+ return NULL;
default:
// dead.
*root = evacuate(*root);
}
-static void
-addBlock(step *stp)
-{
- bdescr *bd = allocBlock();
- bd->gen_no = stp->gen_no;
- bd->step = stp;
-
- if (stp->gen_no <= N) {
- bd->flags = BF_EVACUATED;
- } else {
- bd->flags = 0;
- }
-
- stp->hp_bd->free = stp->hp;
- stp->hp_bd->link = bd;
- stp->hp = bd->start;
- stp->hpLim = stp->hp + BLOCK_SIZE_W;
- stp->hp_bd = bd;
- stp->n_to_blocks++;
- new_blocks++;
-}
-
-
-static __inline__ void
+STATIC_INLINE void
upd_evacuee(StgClosure *p, StgClosure *dest)
{
- p->header.info = &stg_EVACUATED_info;
- ((StgEvacuated *)p)->evacuee = dest;
+ // not true: (ToDo: perhaps it should be)
+ // ASSERT(Bdescr((P_)dest)->flags & BF_EVACUATED);
+ SET_INFO(p, &stg_EVACUATED_info);
+ ((StgEvacuated *)p)->evacuee = dest;
}
-static __inline__ StgClosure *
+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
* necessary.
*/
if (stp->hp + size >= stp->hpLim) {
- addBlock(stp);
+ 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;
}
-/* Special version of copy() for when we only want to copy the info
- * pointer of an object, but reserve some padding after it. This is
- * used to optimise evacuation of BLACKHOLEs.
- */
-
-
-static StgClosure *
-copyPart(StgClosure *src, nat size_to_reserve, nat size_to_copy, step *stp)
+// 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)
{
- P_ dest, to, from;
+ StgPtr to, from;
+ nat i;
#ifdef PROFILING
// @LDV profiling
- nat size_to_copy_org = size_to_copy;
+ nat size_org = size;
#endif
- TICK_GC_WORDS_COPIED(size_to_copy);
+ 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) {
-#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) {
- addBlock(stp);
- }
+ /* 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
+ * pointer of an object, but reserve some padding after it. This is
+ * used to optimise evacuation of BLACKHOLEs.
+ */
+
+
+static StgClosure *
+copyPart(StgClosure *src, nat size_to_reserve, nat size_to_copy, step *stp)
+{
+ P_ dest, to, from;
+#ifdef PROFILING
+ // @LDV profiling
+ nat size_to_copy_org = size_to_copy;
+#endif
+
+ TICK_GC_WORDS_COPIED(size_to_copy);
+ if (stp->gen_no < evac_gen) {
+ if (eager_promotion) {
+ stp = &generations[evac_gen].steps[0];
+ } else {
+ failed_to_evac = rtsTrue;
+ }
+ }
+
+ if (stp->hp + size_to_reserve >= stp->hpLim) {
+ gc_alloc_block(stp);
+ }
for(to = stp->hp, from = (P_)src; size_to_copy>0; --size_to_copy) {
*to++ = *from++;
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;
}
Evacuate a large object
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.
+ step->large_objects list, and linking it on to the (singly-linked)
+ step->new_large_objects list, from where it will be scavenged later.
Convention: bd->flags has BF_EVACUATED set for a large object
that has been evacuated, or unset otherwise.
-------------------------------------------------------------------------- */
-static inline void
+STATIC_INLINE void
evacuate_large(StgPtr p)
{
bdescr *bd = Bdescr(p);
*/
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;
}
/* -----------------------------------------------------------------------------
- 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 *stp;
-
- stp = &gen->steps[0];
-
- /* chain a new block onto the to-space for the destination step if
- * necessary.
- */
- if (stp->hp + sizeofW(StgIndOldGen) >= stp->hpLim) {
- addBlock(stp);
- }
-
- q = (StgMutVar *)stp->hp;
- stp->hp += sizeofW(StgMutVar);
-
- SET_HDR(q,&stg_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.
if M < evac_gen set failed_to_evac flag to indicate that we
didn't manage to evacuate this object into evac_gen.
+
+ OPTIMISATION NOTES:
+
+ evacuate() is the single most important function performance-wise
+ in the GC. Various things have been tried to speed it up, but as
+ far as I can tell the code generated by gcc 3.2 with -O2 is about
+ as good as it's going to get. We pass the argument to evacuate()
+ in a register using the 'regparm' attribute (see the prototype for
+ evacuate() near the top of this file).
+
+ Changing evacuate() to take an (StgClosure **) rather than
+ returning the new pointer seems attractive, because we can avoid
+ writing back the pointer when it hasn't changed (eg. for a static
+ object, or an object in a generation > N). However, I tried it and
+ it doesn't help. One reason is that the (StgClosure **) pointer
+ gets spilled to the stack inside evacuate(), resulting in far more
+ extra reads/writes than we save.
-------------------------------------------------------------------------- */
-static StgClosure *
+REGPARM1 static StgClosure *
evacuate(StgClosure *q)
{
+#if defined(PAR)
StgClosure *to;
+#endif
bdescr *bd = NULL;
step *stp;
const StgInfoTable *info;
loop:
- if (HEAP_ALLOCED(q)) {
- bd = Bdescr((P_)q);
+ ASSERT(LOOKS_LIKE_CLOSURE_PTR(q));
- // not a group head: find the group head
- if (bd->blocks == 0) { bd = bd->link; }
+ if (!HEAP_ALLOCED(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 (!major_gc) 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;
- }
+ info = get_itbl(q);
+ switch (info->type) {
- /* If the object is in a step that we're compacting, then we
- * need to use an alternative evacuate procedure.
- */
- if (bd->step->is_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;
- }
+ 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));
+ }
+ }
- stp = bd->step->to;
+ bd = Bdescr((P_)q);
+
+ if (bd->gen_no > N) {
+ /* Can't evacuate this object, because it's in a generation
+ * older than the ones we're collecting. Let's hope that it's
+ * in evac_gen or older, or we will have to arrange to track
+ * this pointer using the mutable list.
+ */
+ if (bd->gen_no < evac_gen) {
+ // nope
+ failed_to_evac = rtsTrue;
+ TICK_GC_FAILED_PROMOTION();
+ }
+ return 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(q && (LOOKS_LIKE_GHC_INFO(GET_INFO(q))
- || IS_HUGS_CONSTR_INFO(GET_INFO(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:
- to = copy(q,sizeW_fromITBL(info),stp);
- return to;
+ return copy(q,sizeW_fromITBL(info),stp);
case CONSTR_0_1:
{
(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: // here because of MIN_UPD_SIZE
+ case THUNK_1_0:
case THUNK_0_1:
+ 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:
- case BCO:
return copy(q,sizeW_fromITBL(info),stp);
+ case BCO:
+ return copy(q,bco_sizeW((StgBCO *)q),stp);
+
case CAF_BLACKHOLE:
case SE_CAF_BLACKHOLE:
case SE_BLACKHOLE:
case BLACKHOLE:
return copyPart(q,BLACKHOLE_sizeW(),sizeofW(StgHeader),stp);
- case BLACKHOLE_BQ:
- to = copy(q,BLACKHOLE_sizeW(),stp);
- return to;
-
case THUNK_SELECTOR:
{
- const StgInfoTable* selectee_info;
- 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:
- case CONSTR_NOCAF_STATIC:
- {
- StgWord offset = info->layout.selector_offset;
-
- // check that the size is in range
- ASSERT(offset <
- (StgWord32)(selectee_info->layout.payload.ptrs +
- selectee_info->layout.payload.nptrs));
-
- // perform the selection!
- q = selectee->payload[offset];
+ StgClosure *p;
+ const StgInfoTable *info_ptr;
- /* if we're already in to-space, there's no need to continue
- * with the evacuation, just update the source address with
- * a pointer to the (evacuated) constructor field.
- */
- if (HEAP_ALLOCED(q)) {
- bdescr *bd = Bdescr((P_)q);
- if (bd->flags & BF_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,
- * (but not the constructor itself)
- */
- goto loop;
+ if (thunk_selector_depth > MAX_THUNK_SELECTOR_DEPTH) {
+ return copy(q,THUNK_SELECTOR_sizeW(),stp);
}
- case IND:
- case IND_STATIC:
- case IND_PERM:
- case IND_OLDGEN:
- case IND_OLDGEN_PERM:
- selectee = ((StgInd *)selectee)->indirectee;
- goto selector_loop;
+ // stashed away for LDV profiling, see below
+ info_ptr = q->header.info;
- case EVACUATED:
- selectee = ((StgEvacuated *)selectee)->evacuee;
- goto selector_loop;
+ p = eval_thunk_selector(info->layout.selector_offset,
+ (StgSelector *)q);
- case THUNK_SELECTOR:
-# if 0
- /* Disabled 03 April 2001 by JRS; it seems to cause the GC (or
- something) to go into an infinite loop when the nightly
- stage2 compiles PrelTup.lhs. */
-
- /* we can't recurse indefinitely in evacuate(), so set a
- * limit on the number of times we can go around this
- * loop.
- */
- if (thunk_selector_depth < MAX_THUNK_SELECTOR_DEPTH) {
- bdescr *bd;
- bd = Bdescr((P_)selectee);
- if (!bd->flags & BF_EVACUATED) {
- thunk_selector_depth++;
- selectee = evacuate(selectee);
- thunk_selector_depth--;
- goto selector_loop;
- }
- }
- // otherwise, fall through...
-# endif
+ if (p == NULL) {
+ return copy(q,THUNK_SELECTOR_sizeW(),stp);
+ } else {
+ StgClosure *val;
+ // q is still BLACKHOLE'd.
+ thunk_selector_depth++;
+ val = evacuate(p);
+ thunk_selector_depth--;
- case AP_UPD:
- 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 CAF_BLACKHOLE:
- case SE_CAF_BLACKHOLE:
- case SE_BLACKHOLE:
- case BLACKHOLE:
- case BLACKHOLE_BQ:
- // not evaluated yet
- break;
+#ifdef PROFILING
+ // 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
-#if defined(PAR)
- // a copy of the top-level cases below
- case RBH: // cf. BLACKHOLE_BQ
- {
- //StgInfoTable *rip = get_closure_info(q, &size, &ptrs, &nonptrs, &vhs, str);
- to = copy(q,BLACKHOLE_sizeW(),stp);
- //ToDo: derive size etc from reverted IP
- //to = copy(q,size,stp);
- // recordMutable((StgMutClosure *)to);
- return to;
- }
-
- case BLOCKED_FETCH:
- ASSERT(sizeofW(StgBlockedFetch) >= MIN_NONUPD_SIZE);
- to = copy(q,sizeofW(StgBlockedFetch),stp);
- return to;
+ // 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;
-# ifdef DIST
- case REMOTE_REF:
-# endif
- case FETCH_ME:
- ASSERT(sizeofW(StgBlockedFetch) >= MIN_UPD_SIZE);
- to = copy(q,sizeofW(StgFetchMe),stp);
- return to;
-
- case FETCH_ME_BQ:
- ASSERT(sizeofW(StgBlockedFetch) >= MIN_UPD_SIZE);
- to = copy(q,sizeofW(StgFetchMeBlockingQueue),stp);
- return to;
-#endif
+ // For the purposes of LDV profiling, we have created an
+ // indirection.
+ LDV_RECORD_CREATE(q);
- default:
- barf("evacuate: THUNK_SELECTOR: strange selectee %d",
- (int)(selectee_info->type));
- }
+ return val;
+ }
}
- return copy(q,THUNK_SELECTOR_sizeW(),stp);
case IND:
case IND_OLDGEN:
q = ((StgInd*)q)->indirectee;
goto loop;
- 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:
- /* 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:
case UPDATE_FRAME:
case STOP_FRAME:
case CATCH_FRAME:
- case SEQ_FRAME:
+ case CATCH_STM_FRAME:
+ case CATCH_RETRY_FRAME:
+ case ATOMICALLY_FRAME:
// shouldn't see these
barf("evacuate: stack frame at %p\n", q);
- case AP_UPD:
case PAP:
- /* PAPs and AP_UPDs are special - the payload is a copy of a chunk
- * of stack, tagging and all.
- */
return copy(q,pap_sizeW((StgPAP*)q),stp);
+ case AP:
+ return copy(q,ap_sizeW((StgAP*)q),stp);
+
+ case AP_STACK:
+ return copy(q,ap_stack_sizeW((StgAP_STACK*)q),stp);
+
case EVACUATED:
/* Already evacuated, just return the forwarding address.
* HOWEVER: if the requested destination generation (evac_gen) is
* 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 (Bdescr((P_)p)->gen_no < evac_gen) {
+ if (HEAP_ALLOCED(p) && Bdescr((P_)p)->gen_no < evac_gen) {
failed_to_evac = rtsTrue;
TICK_GC_FAILED_PROMOTION();
}
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
return copy(q,mut_arr_ptrs_sizeW((StgMutArrPtrs *)q),stp);
* list it contains.
*/
{
- StgTSO *new_tso = (StgTSO *)copy((StgClosure *)tso,tso_sizeW(tso),stp);
+ StgTSO *new_tso;
+ StgPtr p, q;
+
+ new_tso = (StgTSO *)copyPart((StgClosure *)tso,
+ tso_sizeW(tso),
+ sizeofW(StgTSO), stp);
move_TSO(tso, new_tso);
+ for (p = tso->sp, q = new_tso->sp;
+ p < tso->stack+tso->stack_size;) {
+ *q++ = *p++;
+ }
+
return (StgClosure *)new_tso;
}
}
#if defined(PAR)
- case RBH: // cf. BLACKHOLE_BQ
+ case RBH:
{
//StgInfoTable *rip = get_closure_info(q, &size, &ptrs, &nonptrs, &vhs, str);
to = copy(q,BLACKHOLE_sizeW(),stp);
//ToDo: derive size etc from reverted IP
//to = copy(q,size,stp);
IF_DEBUG(gc,
- belch("@@ evacuate: RBH %p (%s) to %p (%s)",
+ debugBelch("@@ evacuate: RBH %p (%s) to %p (%s)",
q, info_type(q), to, info_type(to)));
return to;
}
case BLOCKED_FETCH:
- ASSERT(sizeofW(StgBlockedFetch) >= MIN_NONUPD_SIZE);
+ ASSERT(sizeofW(StgBlockedFetch) >= MIN_PAYLOD_SIZE);
to = copy(q,sizeofW(StgBlockedFetch),stp);
IF_DEBUG(gc,
- belch("@@ evacuate: %p (%s) to %p (%s)",
+ debugBelch("@@ evacuate: %p (%s) to %p (%s)",
q, info_type(q), to, info_type(to)));
return to;
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,
- belch("@@ evacuate: %p (%s) to %p (%s)",
+ debugBelch("@@ evacuate: %p (%s) to %p (%s)",
q, info_type(q), to, info_type(to)));
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,
- belch("@@ evacuate: %p (%s) to %p (%s)",
+ debugBelch("@@ evacuate: %p (%s) to %p (%s)",
q, info_type(q), to, info_type(to)));
return to;
#endif
+ case TREC_HEADER:
+ return copy(q,sizeofW(StgTRecHeader),stp);
+
+ case TVAR_WAIT_QUEUE:
+ return copy(q,sizeofW(StgTVarWaitQueue),stp);
+
+ case TVAR:
+ return copy(q,sizeofW(StgTVar),stp);
+
+ case TREC_CHUNK:
+ return copy(q,sizeofW(StgTRecChunk),stp);
+
default:
barf("evacuate: strange closure type %d", (int)(info->type));
}
}
/* -----------------------------------------------------------------------------
- move_TSO is called to update the TSO structure after it has been
- moved from one place to another.
- -------------------------------------------------------------------------- */
+ Evaluate a THUNK_SELECTOR if possible.
-void
-move_TSO(StgTSO *src, StgTSO *dest)
-{
- ptrdiff_t diff;
+ returns: NULL if we couldn't evaluate this THUNK_SELECTOR, or
+ a closure pointer if we evaluated it and this is the result. Note
+ that "evaluating" the THUNK_SELECTOR doesn't necessarily mean
+ reducing it to HNF, just that we have eliminated the selection.
+ The result might be another thunk, or even another THUNK_SELECTOR.
- // relocate the stack pointers...
- diff = (StgPtr)dest - (StgPtr)src; // In *words*
- dest->sp = (StgPtr)dest->sp + diff;
- dest->su = (StgUpdateFrame *) ((P_)dest->su + diff);
+ If the return value is non-NULL, the original selector thunk has
+ 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.
- relocate_stack(dest, diff);
-}
+ ***
+ ToDo: the treatment of THUNK_SELECTORS could be improved in the
+ following way (from a suggestion by Ian Lynagh):
-/* -----------------------------------------------------------------------------
- relocate_stack is called to update the linkage between
- UPDATE_FRAMEs (and SEQ_FRAMEs etc.) when a stack is moved from one
- place to another.
- -------------------------------------------------------------------------- */
+ We can have a chain like this:
-StgTSO *
-relocate_stack(StgTSO *dest, ptrdiff_t diff)
-{
- StgUpdateFrame *su;
- StgCatchFrame *cf;
- StgSeqFrame *sf;
+ sel_0 --> (a,b)
+ |
+ |-----> sel_0 --> (a,b)
+ |
+ |-----> sel_0 --> ...
- su = dest->su;
+ 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().
- while ((P_)su < dest->stack + dest->stack_size) {
- switch (get_itbl(su)->type) {
-
- // GCC actually manages to common up these three cases!
+ We could eliminate the depth bound in this case, in the following
+ way:
- case UPDATE_FRAME:
- su->link = (StgUpdateFrame *) ((StgPtr)su->link + diff);
- su = su->link;
- continue;
+ - 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).
- case CATCH_FRAME:
- cf = (StgCatchFrame *)su;
- cf->link = (StgUpdateFrame *) ((StgPtr)cf->link + diff);
- su = cf->link;
- continue;
+ - in a second pass, traverse the chain again updating all
+ THUNK_SEELCTORS that we find on the way with indirections to
+ the value.
- case SEQ_FRAME:
- sf = (StgSeqFrame *)su;
- sf->link = (StgUpdateFrame *) ((StgPtr)sf->link + diff);
- su = sf->link;
- continue;
+ - if we encounter a "marked" THUNK_SELECTOR in a normal
+ evacuate(), we konw it can't be updated so just evac it.
- case STOP_FRAME:
- // all done!
- break;
+ Program that illustrates the problem:
- default:
- barf("relocate_stack %d", (int)(get_itbl(su)->type));
- }
- break;
- }
+ foo [] = ([], [])
+ foo (x:xs) = let (ys, zs) = foo xs
+ in if x >= 0 then (x:ys, zs) else (ys, x:zs)
- return dest;
-}
+ main = bar [1..(100000000::Int)]
+ bar xs = (\(ys, zs) -> print ys >> print zs) (foo xs)
+ -------------------------------------------------------------------------- */
+static inline rtsBool
+is_to_space ( StgClosure *p )
+{
+ bdescr *bd;
+
+ bd = Bdescr((StgPtr)p);
+ if (HEAP_ALLOCED(p) &&
+ ((bd->flags & BF_EVACUATED)
+ || ((bd->flags & BF_COMPACTED) &&
+ is_marked((P_)p,bd)))) {
+ return rtsTrue;
+ } else {
+ return rtsFalse;
+ }
+}
-static inline void
-scavenge_srt(const StgInfoTable *info)
+static StgClosure *
+eval_thunk_selector( nat field, StgSelector * p )
{
- StgClosure **srt, **srt_end;
+ StgInfoTable *info;
+ const StgInfoTable *info_ptr;
+ StgClosure *selectee;
+
+ selectee = p->selectee;
- /* evacuate the SRT. If srt_len is zero, then there isn't an
- * srt field in the info table. That's ok, because we'll
- * never dereference it.
- */
- srt = (StgClosure **)(info->srt);
- srt_end = srt + info->srt_len;
- for (; srt < srt_end; 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 ENABLE_WIN32_DLL_SUPPORT
- if ( (unsigned long)(*srt) & 0x1 ) {
- evacuate(*stgCast(StgClosure**,(stgCast(unsigned long, *srt) & ~0x1)));
- } else {
- evacuate(*srt);
+ // Save the real info pointer (NOTE: not the same as get_itbl()).
+ info_ptr = p->header.info;
+
+ // If the THUNK_SELECTOR is in a generation that we are not
+ // collecting, then bail out early. We won't be able to save any
+ // space in any case, and updating with an indirection is trickier
+ // in an old gen.
+ if (Bdescr((StgPtr)p)->gen_no > N) {
+ return NULL;
}
-#else
- evacuate(*srt);
-#endif
- }
-}
+
+ // BLACKHOLE the selector thunk, since it is now under evaluation.
+ // This is important to stop us going into an infinite loop if
+ // this selector thunk eventually refers to itself.
+ SET_INFO(p,&stg_BLACKHOLE_info);
+
+selector_loop:
+
+ // We don't want to end up in to-space, because this causes
+ // problems when the GC later tries to evacuate the result of
+ // eval_thunk_selector(). There are various ways this could
+ // happen:
+ //
+ // 1. following an IND_STATIC
+ //
+ // 2. when the old generation is compacted, the mark phase updates
+ // from-space pointers to be to-space pointers, and we can't
+ // reliably tell which we're following (eg. from an IND_STATIC).
+ //
+ // 3. compacting GC again: if we're looking at a constructor in
+ // the compacted generation, it might point directly to objects
+ // in to-space. We must bale out here, otherwise doing the selection
+ // will result in a to-space pointer being returned.
+ //
+ // (1) is dealt with using a BF_EVACUATED test on the
+ // selectee. (2) and (3): we can tell if we're looking at an
+ // object in the compacted generation that might point to
+ // to-space objects by testing that (a) it is BF_COMPACTED, (b)
+ // the compacted generation is being collected, and (c) the
+ // object is marked. Only a marked object may have pointers that
+ // point to to-space objects, because that happens when
+ // scavenging.
+ //
+ // The to-space test is now embodied in the in_to_space() inline
+ // function, as it is re-used below.
+ //
+ if (is_to_space(selectee)) {
+ goto bale_out;
+ }
+
+ info = get_itbl(selectee);
+ switch (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:
+ case CONSTR_NOCAF_STATIC:
+ // check that the size is in range
+ ASSERT(field < (StgWord32)(info->layout.payload.ptrs +
+ info->layout.payload.nptrs));
+
+ // Select the right field from the constructor, and check
+ // that the result isn't in to-space. It might be in
+ // to-space if, for example, this constructor contains
+ // pointers to younger-gen objects (and is on the mut-once
+ // list).
+ //
+ {
+ StgClosure *q;
+ q = selectee->payload[field];
+ if (is_to_space(q)) {
+ goto bale_out;
+ } else {
+ return q;
+ }
+ }
+
+ case IND:
+ case IND_PERM:
+ case IND_OLDGEN:
+ case IND_OLDGEN_PERM:
+ case IND_STATIC:
+ selectee = ((StgInd *)selectee)->indirectee;
+ goto selector_loop;
+
+ case EVACUATED:
+ // We don't follow pointers into to-space; the constructor
+ // has already been evacuated, so we won't save any space
+ // leaks by evaluating this selector thunk anyhow.
+ break;
+
+ case THUNK_SELECTOR:
+ {
+ StgClosure *val;
+
+ // check that we don't recurse too much, re-using the
+ // depth bound also used in evacuate().
+ if (thunk_selector_depth >= MAX_THUNK_SELECTOR_DEPTH) {
+ break;
+ }
+ thunk_selector_depth++;
+
+ val = eval_thunk_selector(info->layout.selector_offset,
+ (StgSelector *)selectee);
+
+ thunk_selector_depth--;
+
+ if (val == NULL) {
+ break;
+ } else {
+ // We evaluated this selector thunk, so update it with
+ // an indirection. NOTE: we don't use UPD_IND here,
+ // because we are guaranteed that p is in a generation
+ // that we are collecting, and we never want to put the
+ // indirection on a mutable list.
+#ifdef PROFILING
+ // For the purposes of LDV profiling, we have destroyed
+ // the original selector thunk.
+ SET_INFO(p, info_ptr);
+ LDV_RECORD_DEAD_FILL_SLOP_DYNAMIC(selectee);
+#endif
+ ((StgInd *)selectee)->indirectee = val;
+ SET_INFO(selectee,&stg_IND_info);
+
+ // For the purposes of LDV profiling, we have created an
+ // indirection.
+ LDV_RECORD_CREATE(selectee);
+
+ selectee = val;
+ goto selector_loop;
+ }
+ }
+
+ case AP:
+ case AP_STACK:
+ 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 CAF_BLACKHOLE:
+ case SE_CAF_BLACKHOLE:
+ case SE_BLACKHOLE:
+ case BLACKHOLE:
+#if defined(PAR)
+ case RBH:
+ case BLOCKED_FETCH:
+# ifdef DIST
+ case REMOTE_REF:
+# endif
+ case FETCH_ME:
+ case FETCH_ME_BQ:
+#endif
+ // not evaluated yet
+ break;
+
+ default:
+ barf("eval_thunk_selector: strange selectee %d",
+ (int)(info->type));
+ }
+
+bale_out:
+ // We didn't manage to evaluate this thunk; restore the old info pointer
+ SET_INFO(p, info_ptr);
+ return NULL;
+}
+
+/* -----------------------------------------------------------------------------
+ move_TSO is called to update the TSO structure after it has been
+ moved from one place to another.
+ -------------------------------------------------------------------------- */
+
+void
+move_TSO (StgTSO *src, StgTSO *dest)
+{
+ ptrdiff_t diff;
+
+ // relocate the stack pointer...
+ diff = (StgPtr)dest - (StgPtr)src; // In *words*
+ dest->sp = (StgPtr)dest->sp + diff;
+}
+
+/* Similar to scavenge_large_bitmap(), but we don't write back the
+ * pointers we get back from evacuate().
+ */
+static void
+scavenge_large_srt_bitmap( StgLargeSRT *large_srt )
+{
+ nat i, b, size;
+ StgWord bitmap;
+ StgClosure **p;
+
+ b = 0;
+ bitmap = large_srt->l.bitmap[b];
+ size = (nat)large_srt->l.size;
+ p = (StgClosure **)large_srt->srt;
+ for (i = 0; i < size; ) {
+ if ((bitmap & 1) != 0) {
+ evacuate(*p);
+ }
+ i++;
+ p++;
+ if (i % BITS_IN(W_) == 0) {
+ b++;
+ bitmap = large_srt->l.bitmap[b];
+ } else {
+ bitmap = bitmap >> 1;
+ }
+ }
+}
+
+/* evacuate the SRT. If srt_bitmap is zero, then there isn't an
+ * srt field in the info table. That's ok, because we'll
+ * never dereference it.
+ */
+STATIC_INLINE void
+scavenge_srt (StgClosure **srt, nat srt_bitmap)
+{
+ nat bitmap;
+ StgClosure **p;
+
+ bitmap = srt_bitmap;
+ p = srt;
+
+ if (bitmap == (StgHalfWord)(-1)) {
+ scavenge_large_srt_bitmap( (StgLargeSRT *)srt );
+ return;
+ }
+
+ while (bitmap != 0) {
+ if ((bitmap & 1) != 0) {
+#ifdef ENABLE_WIN32_DLL_SUPPORT
+ // 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.
+ if ( (unsigned long)(*srt) & 0x1 ) {
+ evacuate(*stgCast(StgClosure**,(stgCast(unsigned long, *srt) & ~0x1)));
+ } else {
+ evacuate(*p);
+ }
+#else
+ evacuate(*p);
+#endif
+ }
+ p++;
+ bitmap = bitmap >> 1;
+ }
+}
+
+
+STATIC_INLINE void
+scavenge_thunk_srt(const StgInfoTable *info)
+{
+ 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);
+}
+
+STATIC_INLINE void
+scavenge_fun_srt(const StgInfoTable *info)
+{
+ 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);
+}
/* -----------------------------------------------------------------------------
Scavenge a TSO.
static void
scavengeTSO (StgTSO *tso)
{
- // chase the link field for any TSOs on the same queue
- (StgClosure *)tso->link = evacuate((StgClosure *)tso->link);
- if ( tso->why_blocked == BlockedOnMVar
- || tso->why_blocked == BlockedOnBlackHole
- || tso->why_blocked == BlockedOnException
+ if ( tso->why_blocked == BlockedOnMVar
+ || tso->why_blocked == BlockedOnBlackHole
+ || tso->why_blocked == BlockedOnException
#if defined(PAR)
- || tso->why_blocked == BlockedOnGA
- || tso->why_blocked == BlockedOnGA_NoSend
+ || tso->why_blocked == BlockedOnGA
+ || tso->why_blocked == BlockedOnGA_NoSend
#endif
- ) {
- tso->block_info.closure = evacuate(tso->block_info.closure);
- }
- if ( tso->blocked_exceptions != NULL ) {
- tso->blocked_exceptions =
- (StgTSO *)evacuate((StgClosure *)tso->blocked_exceptions);
- }
- // scavenge this thread's stack
- scavenge_stack(tso->sp, &(tso->stack[tso->stack_size]));
+ ) {
+ tso->block_info.closure = evacuate(tso->block_info.closure);
+ }
+ if ( tso->blocked_exceptions != NULL ) {
+ tso->blocked_exceptions =
+ (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);
+
+ // scavenge this thread's stack
+ scavenge_stack(tso->sp, &(tso->stack[tso->stack_size]));
+}
+
+/* -----------------------------------------------------------------------------
+ Blocks of function args occur on the stack (at the top) and
+ in PAPs.
+ -------------------------------------------------------------------------- */
+
+STATIC_INLINE StgPtr
+scavenge_arg_block (StgFunInfoTable *fun_info, StgClosure **args)
+{
+ StgPtr p;
+ StgWord bitmap;
+ nat size;
+
+ p = (StgPtr)args;
+ switch (fun_info->f.fun_type) {
+ case ARG_GEN:
+ bitmap = BITMAP_BITS(fun_info->f.b.bitmap);
+ size = BITMAP_SIZE(fun_info->f.b.bitmap);
+ goto small_bitmap;
+ case ARG_GEN_BIG:
+ size = GET_FUN_LARGE_BITMAP(fun_info)->size;
+ scavenge_large_bitmap(p, GET_FUN_LARGE_BITMAP(fun_info), size);
+ p += size;
+ break;
+ default:
+ bitmap = BITMAP_BITS(stg_arg_bitmaps[fun_info->f.fun_type]);
+ size = BITMAP_SIZE(stg_arg_bitmaps[fun_info->f.fun_type]);
+ small_bitmap:
+ while (size > 0) {
+ if ((bitmap & 1) == 0) {
+ *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
+ }
+ p++;
+ bitmap = bitmap >> 1;
+ size--;
+ }
+ break;
+ }
+ return p;
+}
+
+STATIC_INLINE StgPtr
+scavenge_PAP_payload (StgClosure *fun, StgClosure **payload, StgWord size)
+{
+ StgPtr p;
+ StgWord bitmap;
+ StgFunInfoTable *fun_info;
+
+ fun_info = get_fun_itbl(fun);
+ ASSERT(fun_info->i.type != PAP);
+ p = (StgPtr)payload;
+
+ switch (fun_info->f.fun_type) {
+ case ARG_GEN:
+ bitmap = BITMAP_BITS(fun_info->f.b.bitmap);
+ goto small_bitmap;
+ case ARG_GEN_BIG:
+ scavenge_large_bitmap(p, GET_FUN_LARGE_BITMAP(fun_info), size);
+ p += size;
+ break;
+ case ARG_BCO:
+ 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:
+ while (size > 0) {
+ if ((bitmap & 1) == 0) {
+ *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
+ }
+ p++;
+ bitmap = bitmap >> 1;
+ size--;
+ }
+ break;
+ }
+ 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);
}
/* -----------------------------------------------------------------------------
continue;
}
+ ASSERT(LOOKS_LIKE_CLOSURE_PTR(p));
info = get_itbl((StgClosure *)p);
- ASSERT(p && (LOOKS_LIKE_GHC_INFO(info) || IS_HUGS_CONSTR_INFO(info)));
+ ASSERT(thunk_selector_depth == 0);
+
q = p;
switch (info->type) {
-
+
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);
+ mvar->head = (StgTSO *)evacuate((StgClosure *)mvar->head);
+ mvar->tail = (StgTSO *)evacuate((StgClosure *)mvar->tail);
+ mvar->value = evacuate((StgClosure *)mvar->value);
evac_gen = saved_evac_gen;
- recordMutable((StgMutClosure *)mvar);
- failed_to_evac = rtsFalse; // mutable.
+ failed_to_evac = rtsTrue; // mutable.
p += sizeofW(StgMVar);
break;
}
- case THUNK_2_0:
case FUN_2_0:
- scavenge_srt(info);
+ scavenge_fun_srt(info);
+ ((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_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]);
break;
case THUNK_1_0:
- scavenge_srt(info);
- ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]);
- p += sizeofW(StgHeader) + 2; // MIN_UPD_SIZE
+ scavenge_thunk_srt(info);
+ ((StgThunk *)p)->payload[0] = evacuate(((StgThunk *)p)->payload[0]);
+ p += sizeofW(StgThunk) + 1;
break;
case FUN_1_0:
- scavenge_srt(info);
+ scavenge_fun_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
+ scavenge_thunk_srt(info);
+ p += sizeofW(StgThunk) + 1;
break;
case FUN_0_1:
- scavenge_srt(info);
+ scavenge_fun_srt(info);
case CONSTR_0_1:
p += sizeofW(StgHeader) + 1;
break;
case THUNK_0_2:
+ scavenge_thunk_srt(info);
+ p += sizeofW(StgThunk) + 2;
+ break;
+
case FUN_0_2:
- scavenge_srt(info);
+ scavenge_fun_srt(info);
case CONSTR_0_2:
p += sizeofW(StgHeader) + 2;
break;
case THUNK_1_1:
+ scavenge_thunk_srt(info);
+ ((StgThunk *)p)->payload[0] = evacuate(((StgThunk *)p)->payload[0]);
+ p += sizeofW(StgThunk) + 2;
+ break;
+
case FUN_1_1:
- scavenge_srt(info);
+ scavenge_fun_srt(info);
case CONSTR_1_1:
((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]);
p += sizeofW(StgHeader) + 2;
break;
case FUN:
+ scavenge_fun_srt(info);
+ goto gen_obj;
+
case THUNK:
- scavenge_srt(info);
- // fall through
+ {
+ StgPtr end;
+
+ scavenge_thunk_srt(info);
+ 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:
- case BCO:
{
StgPtr end;
end = (P_)((StgClosure *)p)->payload + info->layout.payload.ptrs;
for (p = (P_)((StgClosure *)p)->payload; p < end; p++) {
- (StgClosure *)*p = evacuate((StgClosure *)*p);
+ *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
}
p += info->layout.payload.nptrs;
break;
}
+ case BCO: {
+ StgBCO *bco = (StgBCO *)p;
+ bco->instrs = (StgArrWords *)evacuate((StgClosure *)bco->instrs);
+ bco->literals = (StgArrWords *)evacuate((StgClosure *)bco->literals);
+ bco->ptrs = (StgMutArrPtrs *)evacuate((StgClosure *)bco->ptrs);
+ bco->itbls = (StgArrWords *)evacuate((StgClosure *)bco->itbls);
+ p += bco_sizeW(bco);
+ break;
+ }
+
case IND_PERM:
if (stp->gen->no != 0) {
#ifdef PROFILING
LDV_recordDead((StgClosure *)p, sizeofW(StgInd));
#endif
//
- // Todo: maybe use SET_HDR() and remove LDV_recordCreate()?
+ // Todo: maybe use SET_HDR() and remove LDV_RECORD_CREATE()?
//
SET_INFO(((StgClosure *)p), &stg_IND_OLDGEN_PERM_info);
-#ifdef PROFILING
- // @LDV profiling
+
// We pretend that p has just been created.
- LDV_recordCreate((StgClosure *)p);
-#endif
+ LDV_RECORD_CREATE((StgClosure *)p);
}
// fall through
case IND_OLDGEN_PERM:
- ((StgIndOldGen *)p)->indirectee =
- evacuate(((StgIndOldGen *)p)->indirectee);
- if (failed_to_evac) {
- failed_to_evac = rtsFalse;
- recordOldToNewPtrs((StgMutClosure *)p);
- }
- p += sizeofW(StgIndOldGen);
+ ((StgInd *)p)->indirectee = evacuate(((StgInd *)p)->indirectee);
+ 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;
- recordMutable((StgMutClosure *)p);
- failed_to_evac = rtsFalse; // mutable anyhow
- p += sizeofW(StgMutVar);
- break;
+ eager_promotion = saved_eager_promotion;
- case MUT_CONS:
- // ignore these
- failed_to_evac = rtsFalse; // mutable anyhow
+ 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:
p += BLACKHOLE_sizeW();
break;
- case BLACKHOLE_BQ:
- {
- StgBlockingQueue *bh = (StgBlockingQueue *)p;
- (StgClosure *)bh->blocking_queue =
- evacuate((StgClosure *)bh->blocking_queue);
- recordMutable((StgMutClosure *)bh);
- failed_to_evac = rtsFalse;
- p += BLACKHOLE_sizeW();
- break;
- }
-
case THUNK_SELECTOR:
{
StgSelector *s = (StgSelector *)p;
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;
+ // A chunk of stack saved in a heap object
+ case AP_STACK:
+ {
+ StgAP_STACK *ap = (StgAP_STACK *)p;
- pap->fun = evacuate(pap->fun);
- scavenge_stack((P_)pap->payload, (P_)pap->payload + pap->n_args);
- p += pap_sizeW(pap);
+ ap->fun = evacuate(ap->fun);
+ scavenge_stack((StgPtr)ap->payload, (StgPtr)ap->payload + ap->size);
+ p = (StgPtr)ap->payload + ap->size;
break;
}
-
+
+ case PAP:
+ 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++) {
- (StgClosure *)*p = evacuate((StgClosure *)*p);
+ *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
}
- evac_gen = saved_evac_gen;
- recordMutable((StgMutClosure *)q);
- failed_to_evac = rtsFalse; // 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;
}
case MUT_ARR_PTRS_FROZEN:
+ case MUT_ARR_PTRS_FROZEN0:
// follow everything
{
StgPtr next;
next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p);
for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) {
- (StgClosure *)*p = evacuate((StgClosure *)*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;
}
- // 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).
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;
- recordMutable((StgMutClosure *)tso);
- failed_to_evac = rtsFalse; // 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 defined(PAR)
- case RBH: // cf. BLACKHOLE_BQ
+ case RBH:
{
#if 0
nat size, ptrs, nonptrs, vhs;
StgRBH *rbh = (StgRBH *)p;
(StgClosure *)rbh->blocking_queue =
evacuate((StgClosure *)rbh->blocking_queue);
- recordMutable((StgMutClosure *)to);
- failed_to_evac = rtsFalse; // mutable anyhow.
+ failed_to_evac = rtsTrue; // mutable anyhow.
IF_DEBUG(gc,
- belch("@@ scavenge: RBH %p (%s) (new blocking_queue link=%p)",
+ debugBelch("@@ scavenge: RBH %p (%s) (new blocking_queue link=%p)",
p, info_type(p), (StgClosure *)rbh->blocking_queue));
// ToDo: use size of reverted closure here!
p += BLACKHOLE_sizeW();
// follow the link to the rest of the blocking queue
(StgClosure *)bf->link =
evacuate((StgClosure *)bf->link);
- if (failed_to_evac) {
- failed_to_evac = rtsFalse;
- recordMutable((StgMutClosure *)bf);
- }
IF_DEBUG(gc,
- belch("@@ scavenge: %p (%s); node is now %p; exciting, isn't it",
+ debugBelch("@@ scavenge: %p (%s); node is now %p; exciting, isn't it",
bf, info_type((StgClosure *)bf),
bf->node, info_type(bf->node)));
p += sizeofW(StgBlockedFetch);
p += sizeofW(StgFetchMe);
break; // nothing to do in this case
- case FETCH_ME_BQ: // cf. BLACKHOLE_BQ
+ case FETCH_ME_BQ:
{
StgFetchMeBlockingQueue *fmbq = (StgFetchMeBlockingQueue *)p;
(StgClosure *)fmbq->blocking_queue =
evacuate((StgClosure *)fmbq->blocking_queue);
- if (failed_to_evac) {
- failed_to_evac = rtsFalse;
- recordMutable((StgMutClosure *)fmbq);
- }
IF_DEBUG(gc,
- belch("@@ scavenge: %p (%s) exciting, isn't it",
+ debugBelch("@@ scavenge: %p (%s) exciting, isn't it",
p, info_type((StgClosure *)p)));
p += sizeofW(StgFetchMeBlockingQueue);
break;
}
#endif
- default:
- barf("scavenge: unimplemented/strange closure type %d @ %p",
- info->type, p);
- }
-
- /* 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).
+ case TVAR_WAIT_QUEUE:
+ {
+ StgTVarWaitQueue *wq = ((StgTVarWaitQueue *) p);
+ evac_gen = 0;
+ wq->waiting_tso = (StgTSO *)evacuate((StgClosure*)wq->waiting_tso);
+ wq->next_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)wq->next_queue_entry);
+ wq->prev_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)wq->prev_queue_entry);
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ p += sizeofW(StgTVarWaitQueue);
+ break;
+ }
+
+ case TVAR:
+ {
+ StgTVar *tvar = ((StgTVar *) p);
+ evac_gen = 0;
+ tvar->current_value = evacuate((StgClosure*)tvar->current_value);
+ tvar->first_wait_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)tvar->first_wait_queue_entry);
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ p += sizeofW(StgTVar);
+ break;
+ }
+
+ case TREC_HEADER:
+ {
+ StgTRecHeader *trec = ((StgTRecHeader *) p);
+ evac_gen = 0;
+ trec->enclosing_trec = (StgTRecHeader *)evacuate((StgClosure*)trec->enclosing_trec);
+ trec->current_chunk = (StgTRecChunk *)evacuate((StgClosure*)trec->current_chunk);
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ p += sizeofW(StgTRecHeader);
+ break;
+ }
+
+ case TREC_CHUNK:
+ {
+ StgWord i;
+ StgTRecChunk *tc = ((StgTRecChunk *) p);
+ TRecEntry *e = &(tc -> entries[0]);
+ evac_gen = 0;
+ tc->prev_chunk = (StgTRecChunk *)evacuate((StgClosure*)tc->prev_chunk);
+ for (i = 0; i < tc -> next_entry_idx; i ++, e++ ) {
+ e->tvar = (StgTVar *)evacuate((StgClosure*)e->tvar);
+ e->expected_value = evacuate((StgClosure*)e->expected_value);
+ e->new_value = evacuate((StgClosure*)e->new_value);
+ }
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ p += sizeofW(StgTRecChunk);
+ break;
+ }
+
+ default:
+ barf("scavenge: unimplemented/strange closure type %d @ %p",
+ info->type, p);
+ }
+
+ /*
+ * We need to record the current object on the mutable list if
+ * (a) It is actually mutable, or
+ * (b) It contains pointers to a younger generation.
+ * Case (b) arises if we didn't manage to promote everything that
+ * the current object points to into the current generation.
*/
if (failed_to_evac) {
failed_to_evac = rtsFalse;
- mkMutCons((StgClosure *)q, &generations[evac_gen]);
+ if (stp->gen_no > 0) {
+ recordMutableGen((StgClosure *)q, stp->gen);
+ }
}
}
while (!mark_stack_empty()) {
p = pop_mark_stack();
+ ASSERT(LOOKS_LIKE_CLOSURE_PTR(p));
info = get_itbl((StgClosure *)p);
- ASSERT(p && (LOOKS_LIKE_GHC_INFO(info) || IS_HUGS_CONSTR_INFO(info)));
q = p;
switch (info->type) {
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);
+ mvar->head = (StgTSO *)evacuate((StgClosure *)mvar->head);
+ mvar->tail = (StgTSO *)evacuate((StgClosure *)mvar->tail);
+ mvar->value = evacuate((StgClosure *)mvar->value);
evac_gen = saved_evac_gen;
- failed_to_evac = rtsFalse; // mutable.
+ failed_to_evac = rtsTrue; // mutable.
break;
}
case FUN_2_0:
+ scavenge_fun_srt(info);
+ ((StgClosure *)p)->payload[1] = evacuate(((StgClosure *)p)->payload[1]);
+ ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]);
+ break;
+
case THUNK_2_0:
- scavenge_srt(info);
+ 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 FUN_1_0:
case FUN_1_1:
+ scavenge_fun_srt(info);
+ ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]);
+ break;
+
case THUNK_1_0:
case THUNK_1_1:
- scavenge_srt(info);
+ 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]);
case FUN_0_1:
case FUN_0_2:
+ scavenge_fun_srt(info);
+ break;
+
case THUNK_0_1:
case THUNK_0_2:
- scavenge_srt(info);
+ scavenge_thunk_srt(info);
+ break;
+
case CONSTR_0_1:
case CONSTR_0_2:
break;
case FUN:
+ scavenge_fun_srt(info);
+ goto gen_obj;
+
case THUNK:
- scavenge_srt(info);
- // fall through
+ {
+ StgPtr end;
+
+ scavenge_thunk_srt(info);
+ 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:
- case BCO:
{
StgPtr end;
end = (P_)((StgClosure *)p)->payload + info->layout.payload.ptrs;
for (p = (P_)((StgClosure *)p)->payload; p < end; p++) {
- (StgClosure *)*p = evacuate((StgClosure *)*p);
+ *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
}
break;
}
+ case BCO: {
+ StgBCO *bco = (StgBCO *)p;
+ bco->instrs = (StgArrWords *)evacuate((StgClosure *)bco->instrs);
+ bco->literals = (StgArrWords *)evacuate((StgClosure *)bco->literals);
+ bco->ptrs = (StgMutArrPtrs *)evacuate((StgClosure *)bco->ptrs);
+ bco->itbls = (StgArrWords *)evacuate((StgClosure *)bco->itbls);
+ break;
+ }
+
case IND_PERM:
// don't need to do anything here: the only possible case
// is that we're in a 1-space compacting collector, with
case IND_OLDGEN:
case IND_OLDGEN_PERM:
- ((StgIndOldGen *)p)->indirectee =
- evacuate(((StgIndOldGen *)p)->indirectee);
- if (failed_to_evac) {
- recordOldToNewPtrs((StgMutClosure *)p);
- }
- failed_to_evac = rtsFalse;
+ ((StgInd *)p)->indirectee =
+ 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 = rtsFalse;
- break;
-
- case MUT_CONS:
- // ignore these
- failed_to_evac = rtsFalse;
+ 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 ARR_WORDS:
break;
- case BLACKHOLE_BQ:
- {
- StgBlockingQueue *bh = (StgBlockingQueue *)p;
- (StgClosure *)bh->blocking_queue =
- evacuate((StgClosure *)bh->blocking_queue);
- failed_to_evac = rtsFalse;
- break;
- }
-
case THUNK_SELECTOR:
{
StgSelector *s = (StgSelector *)p;
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;
+ // A chunk of stack saved in a heap object
+ case AP_STACK:
+ {
+ StgAP_STACK *ap = (StgAP_STACK *)p;
- pap->fun = evacuate(pap->fun);
- scavenge_stack((P_)pap->payload, (P_)pap->payload + pap->n_args);
+ ap->fun = evacuate(ap->fun);
+ scavenge_stack((StgPtr)ap->payload, (StgPtr)ap->payload + ap->size);
break;
}
+
+ case PAP:
+ 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++) {
- (StgClosure *)*p = evacuate((StgClosure *)*p);
+ *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
}
- evac_gen = saved_evac_gen;
- failed_to_evac = rtsFalse; // 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; // mutable anyhow.
break;
}
case MUT_ARR_PTRS_FROZEN:
+ 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++) {
- (StgClosure *)*p = evacuate((StgClosure *)*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 = rtsFalse;
+ 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 defined(PAR)
- case RBH: // cf. BLACKHOLE_BQ
+ case RBH:
{
#if 0
nat size, ptrs, nonptrs, vhs;
StgInfoTable *rip = get_closure_info(p, &size, &ptrs, &nonptrs, &vhs, str);
#endif
StgRBH *rbh = (StgRBH *)p;
- (StgClosure *)rbh->blocking_queue =
- evacuate((StgClosure *)rbh->blocking_queue);
- recordMutable((StgMutClosure *)rbh);
- failed_to_evac = rtsFalse; // mutable anyhow.
+ bh->blocking_queue =
+ (StgTSO *)evacuate((StgClosure *)bh->blocking_queue);
+ failed_to_evac = rtsTrue; // mutable anyhow.
IF_DEBUG(gc,
- belch("@@ scavenge: RBH %p (%s) (new blocking_queue link=%p)",
+ debugBelch("@@ scavenge: RBH %p (%s) (new blocking_queue link=%p)",
p, info_type(p), (StgClosure *)rbh->blocking_queue));
break;
}
// follow the link to the rest of the blocking queue
(StgClosure *)bf->link =
evacuate((StgClosure *)bf->link);
- if (failed_to_evac) {
- failed_to_evac = rtsFalse;
- recordMutable((StgMutClosure *)bf);
- }
IF_DEBUG(gc,
- belch("@@ scavenge: %p (%s); node is now %p; exciting, isn't it",
+ debugBelch("@@ scavenge: %p (%s); node is now %p; exciting, isn't it",
bf, info_type((StgClosure *)bf),
bf->node, info_type(bf->node)));
break;
case FETCH_ME:
break; // nothing to do in this case
- case FETCH_ME_BQ: // cf. BLACKHOLE_BQ
+ case FETCH_ME_BQ:
{
StgFetchMeBlockingQueue *fmbq = (StgFetchMeBlockingQueue *)p;
(StgClosure *)fmbq->blocking_queue =
evacuate((StgClosure *)fmbq->blocking_queue);
- if (failed_to_evac) {
- failed_to_evac = rtsFalse;
- recordMutable((StgMutClosure *)fmbq);
- }
IF_DEBUG(gc,
- belch("@@ scavenge: %p (%s) exciting, isn't it",
+ debugBelch("@@ scavenge: %p (%s) exciting, isn't it",
p, info_type((StgClosure *)p)));
break;
}
-#endif // PAR
+#endif /* PAR */
+
+ case TVAR_WAIT_QUEUE:
+ {
+ StgTVarWaitQueue *wq = ((StgTVarWaitQueue *) p);
+ evac_gen = 0;
+ wq->waiting_tso = (StgTSO *)evacuate((StgClosure*)wq->waiting_tso);
+ wq->next_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)wq->next_queue_entry);
+ wq->prev_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)wq->prev_queue_entry);
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ break;
+ }
+
+ case TVAR:
+ {
+ StgTVar *tvar = ((StgTVar *) p);
+ evac_gen = 0;
+ tvar->current_value = evacuate((StgClosure*)tvar->current_value);
+ tvar->first_wait_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)tvar->first_wait_queue_entry);
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ break;
+ }
+
+ case TREC_CHUNK:
+ {
+ StgWord i;
+ StgTRecChunk *tc = ((StgTRecChunk *) p);
+ TRecEntry *e = &(tc -> entries[0]);
+ evac_gen = 0;
+ tc->prev_chunk = (StgTRecChunk *)evacuate((StgClosure*)tc->prev_chunk);
+ for (i = 0; i < tc -> next_entry_idx; i ++, e++ ) {
+ e->tvar = (StgTVar *)evacuate((StgClosure*)e->tvar);
+ e->expected_value = evacuate((StgClosure*)e->expected_value);
+ e->new_value = evacuate((StgClosure*)e->new_value);
+ }
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ break;
+ }
+
+ case TREC_HEADER:
+ {
+ StgTRecHeader *trec = ((StgTRecHeader *) p);
+ evac_gen = 0;
+ trec->enclosing_trec = (StgTRecHeader *)evacuate((StgClosure*)trec->enclosing_trec);
+ trec->current_chunk = (StgTRecChunk *)evacuate((StgClosure*)trec->current_chunk);
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ break;
+ }
default:
barf("scavenge_mark_stack: unimplemented/strange closure type %d @ %p",
if (failed_to_evac) {
failed_to_evac = rtsFalse;
- mkMutCons((StgClosure *)q, &generations[evac_gen]);
+ if (evac_gen > 0) {
+ recordMutableGen((StgClosure *)q, &generations[evac_gen]);
+ }
}
// mark the next bit to indicate "scavenged"
// start a new linear scan if the mark stack overflowed at some point
if (mark_stack_overflowed && oldgen_scan_bd == NULL) {
- IF_DEBUG(gc, belch("scavenge_mark_stack: starting linear scan"));
+ 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;
}
nat saved_evac_gen = evac_gen;
rtsBool no_luck;
- ASSERT(p && (LOOKS_LIKE_GHC_INFO(GET_INFO((StgClosure *)p))
- || IS_HUGS_CONSTR_INFO(GET_INFO((StgClosure *)p))));
-
+ ASSERT(LOOKS_LIKE_CLOSURE_PTR(p));
info = get_itbl((StgClosure *)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 MVAR:
+ {
+ StgMVar *mvar = ((StgMVar *)p);
+ evac_gen = 0;
+ mvar->head = (StgTSO *)evacuate((StgClosure *)mvar->head);
+ mvar->tail = (StgTSO *)evacuate((StgClosure *)mvar->tail);
+ mvar->value = evacuate((StgClosure *)mvar->value);
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable.
+ break;
+ }
+
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:
- case IND_OLDGEN_PERM:
{
StgPtr q, end;
end = (StgPtr)((StgClosure *)p)->payload + info->layout.payload.ptrs;
for (q = (StgPtr)((StgClosure *)p)->payload; q < end; q++) {
- (StgClosure *)*q = evacuate((StgClosure *)*q);
+ *q = (StgWord)(StgPtr)evacuate((StgClosure *)*q);
}
break;
}
+ 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);
+ 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 SE_BLACKHOLE:
break;
}
+ case AP_STACK:
+ {
+ StgAP_STACK *ap = (StgAP_STACK *)p;
+
+ ap->fun = evacuate(ap->fun);
+ scavenge_stack((StgPtr)ap->payload, (StgPtr)ap->payload + ap->size);
+ p = (StgPtr)ap->payload + ap->size;
+ break;
+ }
+
+ case PAP:
+ 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
- recordMutable((StgMutClosure *)p);
+ 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++) {
- (StgClosure *)*p = evacuate((StgClosure *)*p);
+ *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
}
- evac_gen = saved_evac_gen;
- failed_to_evac = rtsFalse;
+ 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_FROZEN:
+ 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++) {
- (StgClosure *)*p = evacuate((StgClosure *)*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);
- recordMutable((StgMutClosure *)tso);
- evac_gen = saved_evac_gen;
- failed_to_evac = rtsFalse;
+ 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;
}
- case AP_UPD:
- case PAP:
+#if defined(PAR)
+ case RBH:
{
- StgPAP* pap = (StgPAP *)p;
- pap->fun = evacuate(pap->fun);
- scavenge_stack((P_)pap->payload, (P_)pap->payload + pap->n_args);
+#if 0
+ nat size, ptrs, nonptrs, vhs;
+ char str[80];
+ StgInfoTable *rip = get_closure_info(p, &size, &ptrs, &nonptrs, &vhs, str);
+#endif
+ StgRBH *rbh = (StgRBH *)p;
+ (StgClosure *)rbh->blocking_queue =
+ evacuate((StgClosure *)rbh->blocking_queue);
+ failed_to_evac = rtsTrue; // mutable anyhow.
+ IF_DEBUG(gc,
+ debugBelch("@@ scavenge: RBH %p (%s) (new blocking_queue link=%p)",
+ p, info_type(p), (StgClosure *)rbh->blocking_queue));
+ // ToDo: use size of reverted closure here!
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.
+ case BLOCKED_FETCH:
+ {
+ StgBlockedFetch *bf = (StgBlockedFetch *)p;
+ // follow the pointer to the node which is being demanded
+ (StgClosure *)bf->node =
+ evacuate((StgClosure *)bf->node);
+ // follow the link to the rest of the blocking queue
+ (StgClosure *)bf->link =
+ evacuate((StgClosure *)bf->link);
+ IF_DEBUG(gc,
+ debugBelch("@@ scavenge: %p (%s); node is now %p; exciting, isn't it",
+ bf, info_type((StgClosure *)bf),
+ bf->node, info_type(bf->node)));
break;
+ }
- default:
- barf("scavenge_one: strange object %d", (int)(info->type));
- }
+#ifdef DIST
+ case REMOTE_REF:
+#endif
+ case FETCH_ME:
+ break; // nothing to do in this case
- no_luck = failed_to_evac;
- failed_to_evac = rtsFalse;
- return (no_luck);
-}
+ case FETCH_ME_BQ:
+ {
+ StgFetchMeBlockingQueue *fmbq = (StgFetchMeBlockingQueue *)p;
+ (StgClosure *)fmbq->blocking_queue =
+ evacuate((StgClosure *)fmbq->blocking_queue);
+ IF_DEBUG(gc,
+ debugBelch("@@ scavenge: %p (%s) exciting, isn't it",
+ p, info_type((StgClosure *)p)));
+ break;
+ }
+#endif
-/* -----------------------------------------------------------------------------
- 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)
-{
- const StgInfoTable *info;
- StgMutClosure *p, *next, *new_list;
+ case TVAR_WAIT_QUEUE:
+ {
+ StgTVarWaitQueue *wq = ((StgTVarWaitQueue *) p);
+ evac_gen = 0;
+ wq->waiting_tso = (StgTSO *)evacuate((StgClosure*)wq->waiting_tso);
+ wq->next_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)wq->next_queue_entry);
+ wq->prev_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)wq->prev_queue_entry);
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ break;
+ }
- p = gen->mut_once_list;
- new_list = END_MUT_LIST;
- next = p->mut_link;
+ case TVAR:
+ {
+ StgTVar *tvar = ((StgTVar *) p);
+ evac_gen = 0;
+ tvar->current_value = evacuate((StgClosure*)tvar->current_value);
+ tvar->first_wait_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)tvar->first_wait_queue_entry);
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ break;
+ }
- evac_gen = gen->no;
- failed_to_evac = rtsFalse;
+ case TREC_HEADER:
+ {
+ StgTRecHeader *trec = ((StgTRecHeader *) p);
+ evac_gen = 0;
+ trec->enclosing_trec = (StgTRecHeader *)evacuate((StgClosure*)trec->enclosing_trec);
+ trec->current_chunk = (StgTRecChunk *)evacuate((StgClosure*)trec->current_chunk);
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ break;
+ }
- for (; p != END_MUT_LIST; p = next, next = p->mut_link) {
+ case TREC_CHUNK:
+ {
+ StgWord i;
+ StgTRecChunk *tc = ((StgTRecChunk *) p);
+ TRecEntry *e = &(tc -> entries[0]);
+ evac_gen = 0;
+ tc->prev_chunk = (StgTRecChunk *)evacuate((StgClosure*)tc->prev_chunk);
+ for (i = 0; i < tc -> next_entry_idx; i ++, e++ ) {
+ e->tvar = (StgTVar *)evacuate((StgClosure*)e->tvar);
+ e->expected_value = evacuate((StgClosure*)e->expected_value);
+ e->new_value = evacuate((StgClosure*)e->new_value);
+ }
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ break;
+ }
- // 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);
- /*
- if (info->type==RBH)
- info = REVERT_INFOPTR(info); // if it's an RBH, look at the orig closure
- */
- 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);
-
+ {
+ /* Careful here: a THUNK can be on the mutable list because
+ * it contains pointers to young gen objects. If such a thunk
+ * is updated, the IND_OLDGEN will be added to the mutable
+ * list again, and we'll scavenge it twice. evacuate()
+ * doesn't check whether the object has already been
+ * evacuated, so we perform that check here.
+ */
+ StgClosure *q = ((StgInd *)p)->indirectee;
+ if (HEAP_ALLOCED(q) && Bdescr((StgPtr)q)->flags & BF_EVACUATED) {
+ break;
+ }
+ ((StgInd *)p)->indirectee = evacuate(q);
+ }
+
#if 0 && defined(DEBUG)
if (RtsFlags.DebugFlags.gc)
/* Debugging code to print out the size of the thing we just
} else {
size = gen->steps[0].scan - start;
}
- belch("evac IND_OLDGEN: %ld bytes", size * sizeof(W_));
+ debugBelch("evac IND_OLDGEN: %ld bytes", 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_CONS:
- /* 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.
- */
- if (scavenge_one((StgPtr)((StgMutVar *)p)->var)) {
- /* didn't manage to promote everything, so put the
- * MUT_CONS back on the list.
- */
- p->mut_link = new_list;
- new_list = p;
- }
- continue;
+ break;
default:
- // shouldn't have anything else on the mutables list
- barf("scavenge_mut_once_list: strange object? %d", (int)(info->type));
- }
- }
+ barf("scavenge_one: strange object %d", (int)(info->type));
+ }
- gen->mut_once_list = new_list;
+ 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_mutable_list(generation *gen)
{
- const 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);
- /*
- if (info->type==RBH)
- info = REVERT_INFOPTR(info); // if it's an RBH, look at the orig closure
- */
- switch(info->type) {
-
- 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;
- }
-
- // Happens if a MUT_ARR_PTRS in the old generation is frozen
- case MUT_ARR_PTRS_FROZEN:
- {
- StgPtr end, q;
-
- evac_gen = gen->no;
- end = (P_)p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p);
- for (q = (P_)((StgMutArrPtrs *)p)->payload; q < end; q++) {
- (StgClosure *)*q = evacuate((StgClosure *)*q);
- }
- evac_gen = 0;
- p->mut_link = NULL;
- if (failed_to_evac) {
- failed_to_evac = rtsFalse;
- mkMutCons((StgClosure *)p, gen);
- }
- continue;
- }
-
- case MUT_VAR:
- ((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:
- {
- StgTSO *tso = (StgTSO *)p;
-
- scavengeTSO(tso);
-
- /* 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;
- }
-
- /* Happens if a BLACKHOLE_BQ in the old generation is updated:
- */
- case IND_OLDGEN:
- case IND_OLDGEN_PERM:
- /* Try to pull the indirectee into this generation, so we can
- * remove the indirection from the mutable list.
- */
- evac_gen = gen->no;
- ((StgIndOldGen *)p)->indirectee =
- evacuate(((StgIndOldGen *)p)->indirectee);
- evac_gen = 0;
-
- if (failed_to_evac) {
- failed_to_evac = rtsFalse;
- p->mut_link = gen->mut_once_list;
- gen->mut_once_list = p;
- } else {
- p->mut_link = NULL;
- }
- continue;
-
-#if defined(PAR)
- // HWL: check whether all of these are necessary
-
- case RBH: // cf. BLACKHOLE_BQ
- {
- // nat size, ptrs, nonptrs, vhs;
- // char str[80];
- // StgInfoTable *rip = get_closure_info(p, &size, &ptrs, &nonptrs, &vhs, str);
- StgRBH *rbh = (StgRBH *)p;
- (StgClosure *)rbh->blocking_queue =
- evacuate((StgClosure *)rbh->blocking_queue);
- if (failed_to_evac) {
- failed_to_evac = rtsFalse;
- recordMutable((StgMutClosure *)rbh);
- }
- // ToDo: use size of reverted closure here!
- p += BLACKHOLE_sizeW();
- break;
- }
-
- case BLOCKED_FETCH:
- {
- StgBlockedFetch *bf = (StgBlockedFetch *)p;
- // follow the pointer to the node which is being demanded
- (StgClosure *)bf->node =
- evacuate((StgClosure *)bf->node);
- // follow the link to the rest of the blocking queue
- (StgClosure *)bf->link =
- evacuate((StgClosure *)bf->link);
- if (failed_to_evac) {
- failed_to_evac = rtsFalse;
- recordMutable((StgMutClosure *)bf);
- }
- p += sizeofW(StgBlockedFetch);
- break;
- }
+ bdescr *bd;
+ StgPtr p, q;
-#ifdef DIST
- case REMOTE_REF:
- barf("scavenge_mutable_list: REMOTE_REF %d", (int)(info->type));
+ bd = gen->saved_mut_list;
+
+ evac_gen = gen->no;
+ for (; bd != NULL; bd = bd->link) {
+ 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
- case FETCH_ME:
- p += sizeofW(StgFetchMe);
- break; // nothing to do in this case
- case FETCH_ME_BQ: // cf. BLACKHOLE_BQ
- {
- StgFetchMeBlockingQueue *fmbq = (StgFetchMeBlockingQueue *)p;
- (StgClosure *)fmbq->blocking_queue =
- evacuate((StgClosure *)fmbq->blocking_queue);
- if (failed_to_evac) {
- failed_to_evac = rtsFalse;
- recordMutable((StgMutClosure *)fmbq);
- }
- p += sizeofW(StgFetchMeBlockingQueue);
- 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:
+ ;
+ }
- default:
- // shouldn't have anything else on the mutables list
- barf("scavenge_mutable_list: strange object? %d", (int)(info->type));
+ if (scavenge_one(p)) {
+ // didn't manage to promote everything, so put the
+ // object back on the list.
+ recordMutableGen((StgClosure *)p,gen);
+ }
+ }
}
- }
+
+ // free the old mut_list
+ freeChain(gen->saved_mut_list);
+ gen->saved_mut_list = NULL;
}
list... */
while (p != END_OF_STATIC_LIST) {
+ ASSERT(LOOKS_LIKE_CLOSURE_PTR(p));
info = get_itbl(p);
/*
if (info->type==RBH)
info = REVERT_INFOPTR(info); // if it's an RBH, look at the orig closure
*/
// 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))));
/* 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) {
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).
+ * back on the mutable list of the oldest generation. We
+ * leave it *on* the scavenged_static_objects list, though,
+ * in case we visit this object again.
*/
if (failed_to_evac) {
failed_to_evac = rtsFalse;
- scavenged_static_objects = IND_STATIC_LINK(p);
- ((StgMutClosure *)ind)->mut_link = oldest_gen->mut_once_list;
- oldest_gen->mut_once_list = (StgMutClosure *)ind;
+ recordMutableGen((StgClosure *)p,oldest_gen);
}
break;
}
case THUNK_STATIC:
+ scavenge_thunk_srt(info);
+ break;
+
case FUN_STATIC:
- scavenge_srt(info);
+ scavenge_fun_srt(info);
break;
case CONSTR_STATIC:
next = (P_)p->payload + info->layout.payload.ptrs;
// evacuate the pointers
for (q = (P_)p->payload; q < next; q++) {
- (StgClosure *)*q = evacuate((StgClosure *)*q);
+ *q = (StgWord)(StgPtr)evacuate((StgClosure *)*q);
}
break;
}
}
/* -----------------------------------------------------------------------------
+ scavenge a chunk of memory described by a bitmap
+ -------------------------------------------------------------------------- */
+
+static void
+scavenge_large_bitmap( StgPtr p, StgLargeBitmap *large_bitmap, nat size )
+{
+ nat i, b;
+ StgWord bitmap;
+
+ b = 0;
+ bitmap = large_bitmap->bitmap[b];
+ for (i = 0; i < size; ) {
+ if ((bitmap & 1) == 0) {
+ *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
+ }
+ i++;
+ p++;
+ if (i % BITS_IN(W_) == 0) {
+ b++;
+ bitmap = large_bitmap->bitmap[b];
+ } else {
+ bitmap = bitmap >> 1;
+ }
+ }
+}
+
+STATIC_INLINE StgPtr
+scavenge_small_bitmap (StgPtr p, nat size, StgWord bitmap)
+{
+ while (size > 0) {
+ if ((bitmap & 1) == 0) {
+ *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
+ }
+ p++;
+ bitmap = bitmap >> 1;
+ size--;
+ }
+ return p;
+}
+
+/* -----------------------------------------------------------------------------
scavenge_stack walks over a section of stack and evacuates all the
objects pointed to by it. We can use the same code for walking
- PAPs, since these are just sections of copied stack.
+ AP_STACK_UPDs, since these are just sections of copied stack.
-------------------------------------------------------------------------- */
+
static void
scavenge_stack(StgPtr p, StgPtr stack_end)
{
- StgPtr q;
- const StgInfoTable* info;
+ const StgRetInfoTable* info;
StgWord bitmap;
+ nat size;
- //IF_DEBUG(sanity, belch(" scavenging stack between %p and %p", p, stack_end));
+ //IF_DEBUG(sanity, debugBelch(" scavenging stack between %p and %p", p, stack_end));
/*
* Each time around this loop, we are looking at a chunk of stack
- * that starts with either a pending argument section or an
- * activation record.
+ * that starts with an activation record.
*/
while (p < stack_end) {
- q = *(P_ *)p;
-
- // If we've got a tag, skip over that many words on the stack
- if (IS_ARG_TAG((W_)q)) {
- p += ARG_SIZE(q);
- p++; continue;
- }
-
- /* Is q a pointer to a closure?
- */
- if (! LOOKS_LIKE_GHC_INFO(q) ) {
-#ifdef DEBUG
- if ( 0 && LOOKS_LIKE_STATIC_CLOSURE(q) ) { // Is it a static closure?
- ASSERT(closure_STATIC((StgClosure *)q));
- }
- // otherwise, must be a pointer into the allocation space.
-#endif
-
- (StgClosure *)*p = evacuate((StgClosure *)q);
- p++;
- continue;
- }
+ info = get_ret_itbl((StgClosure *)p);
- /*
- * Otherwise, q must be the info pointer of an activation
- * record. All activation records have 'bitmap' style layout
- * info.
- */
- info = get_itbl((StgClosure *)p);
-
- switch (info->type) {
+ switch (info->i.type) {
- // Dynamic bitmap: the mask is stored on the stack
- case RET_DYN:
- bitmap = ((StgRetDyn *)p)->liveness;
- p = (P_)&((StgRetDyn *)p)->payload[0];
- goto small_bitmap;
-
- // probably a slow-entry point return address:
- case FUN:
- case FUN_STATIC:
- {
-#if 0
- StgPtr old_p = p;
- p++; p++;
- IF_DEBUG(sanity,
- belch("HWL: scavenge_stack: FUN(_STATIC) adjusting p from %p to %p (instead of %p)",
- old_p, p, old_p+1));
-#else
- p++; // what if FHS!=1 !? -- HWL
-#endif
- goto follow_srt;
- }
-
- /* Specialised code for update frames, since they're so common.
- * 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;
-
+ // 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);
-
-#ifndef not_yet
- frame->updatee = evacuate(frame->updatee);
continue;
-#else // specialised code for update frames, not sure if it's worth it.
- StgClosure *to;
- nat type = get_itbl(frame->updatee)->type;
-
- if (type == EVACUATED) {
- frame->updatee = evacuate(frame->updatee);
- continue;
- } else {
- bdescr *bd = Bdescr((P_)frame->updatee);
- step *stp;
- if (bd->gen_no > N) {
- if (bd->gen_no < evac_gen) {
- failed_to_evac = rtsTrue;
- }
- continue;
- }
-
- // Don't promote blackholes
- stp = bd->step;
- if (!(stp->gen_no == 0 &&
- stp->no != 0 &&
- stp->no == stp->gen->n_steps-1)) {
- stp = stp->to;
- }
-
- switch (type) {
- case BLACKHOLE:
- case CAF_BLACKHOLE:
- to = copyPart(frame->updatee, BLACKHOLE_sizeW(),
- sizeofW(StgHeader), stp);
- frame->updatee = to;
- continue;
- case BLACKHOLE_BQ:
- to = copy(frame->updatee, BLACKHOLE_sizeW(), stp);
- frame->updatee = to;
- recordMutable((StgMutClosure *)to);
- continue;
- default:
- /* will never be SE_{,CAF_}BLACKHOLE, since we
- don't push an update frame for single-entry thunks. KSW 1999-01. */
- barf("scavenge_stack: UPDATE_FRAME updatee");
- }
- }
-#endif
- }
// small bitmap (< 32 entries, or 64 on a 64-bit machine)
+ case CATCH_STM_FRAME:
+ case CATCH_RETRY_FRAME:
+ case ATOMICALLY_FRAME:
case STOP_FRAME:
case CATCH_FRAME:
- case SEQ_FRAME:
- case RET_BCO:
case RET_SMALL:
case RET_VEC_SMALL:
- bitmap = info->layout.bitmap;
- p++;
- // this assumes that the payload starts immediately after the info-ptr
- small_bitmap:
- while (bitmap != 0) {
- if ((bitmap & 1) == 0) {
- (StgClosure *)*p = evacuate((StgClosure *)*p);
- }
+ bitmap = BITMAP_BITS(info->i.layout.bitmap);
+ size = BITMAP_SIZE(info->i.layout.bitmap);
+ // NOTE: the payload starts immediately after the info-ptr, we
+ // don't have an StgHeader in the same sense as a heap closure.
p++;
- bitmap = bitmap >> 1;
- }
-
+ p = scavenge_small_bitmap(p, size, bitmap);
+
follow_srt:
- scavenge_srt(info);
- continue;
+ if (major_gc)
+ scavenge_srt((StgClosure **)GET_SRT(info), info->i.srt_bitmap);
+ continue;
+
+ case RET_BCO: {
+ StgBCO *bco;
+ nat size;
+
+ p++;
+ *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
+ bco = (StgBCO *)*p;
+ p++;
+ size = BCO_BITMAP_SIZE(bco);
+ scavenge_large_bitmap(p, BCO_BITMAP(bco), size);
+ p += size;
+ continue;
+ }
// large bitmap (> 32 entries, or > 64 on a 64-bit machine)
case RET_BIG:
case RET_VEC_BIG:
- {
- StgPtr q;
- StgLargeBitmap *large_bitmap;
- nat i;
+ {
+ nat size;
- large_bitmap = info->layout.large_bitmap;
+ size = GET_LARGE_BITMAP(&info->i)->size;
p++;
+ scavenge_large_bitmap(p, GET_LARGE_BITMAP(&info->i), size);
+ p += size;
+ // and don't forget to follow the SRT
+ goto follow_srt;
+ }
- for (i=0; i<large_bitmap->size; i++) {
- bitmap = large_bitmap->bitmap[i];
- q = p + BITS_IN(W_);
- while (bitmap != 0) {
- if ((bitmap & 1) == 0) {
- (StgClosure *)*p = evacuate((StgClosure *)*p);
- }
+ // Dynamic bitmap: the mask is stored on the stack, and
+ // there are a number of non-pointers followed by a number
+ // of pointers above the bitmapped area. (see StgMacros.h,
+ // HEAP_CHK_GEN).
+ case RET_DYN:
+ {
+ StgWord dyn;
+ dyn = ((StgRetDyn *)p)->liveness;
+
+ // traverse the bitmap first
+ bitmap = RET_DYN_LIVENESS(dyn);
+ p = (P_)&((StgRetDyn *)p)->payload[0];
+ size = RET_DYN_BITMAP_SIZE;
+ p = scavenge_small_bitmap(p, size, bitmap);
+
+ // skip over the non-ptr words
+ p += RET_DYN_NONPTRS(dyn) + RET_DYN_NONPTR_REGS_SIZE;
+
+ // follow the ptr words
+ for (size = RET_DYN_PTRS(dyn); size > 0; size--) {
+ *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
p++;
- bitmap = bitmap >> 1;
- }
- if (i+1 < large_bitmap->size) {
- while (p < q) {
- (StgClosure *)*p = evacuate((StgClosure *)*p);
- p++;
- }
- }
}
+ continue;
+ }
- // and don't forget to follow the SRT
+ case RET_FUN:
+ {
+ StgRetFun *ret_fun = (StgRetFun *)p;
+ StgFunInfoTable *fun_info;
+
+ ret_fun->fun = evacuate(ret_fun->fun);
+ fun_info = get_fun_itbl(ret_fun->fun);
+ p = scavenge_arg_block(fun_info, ret_fun->payload);
goto follow_srt;
- }
+ }
default:
- barf("scavenge_stack: weird activation record found on stack: %d", (int)(info->type));
+ barf("scavenge_stack: weird activation record found on stack: %d", (int)(info->i.type));
}
- }
+ }
}
/*-----------------------------------------------------------------------------
p = bd->start;
if (scavenge_one(p)) {
- mkMutCons((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;
- }
-}
-
-/* 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;
+ link = *STATIC_LINK(info, p);
+ *STATIC_LINK(info,p) = NULL;
}
}
{
StgIndStatic *c;
- for (c = (StgIndStatic *)caf_list; c != NULL;
+ for (c = (StgIndStatic *)revertible_caf_list; c != NULL;
c = (StgIndStatic *)c->static_link)
{
- c->header.info = c->saved_info;
+ SET_INFO(c, c->saved_info);
c->saved_info = NULL;
// could, but not necessary: c->static_link = NULL;
}
- caf_list = NULL;
+ revertible_caf_list = NULL;
}
void
{
evac(&c->indirectee);
}
+ for (c = (StgIndStatic *)revertible_caf_list; c != NULL;
+ c = (StgIndStatic *)c->static_link)
+ {
+ evac(&c->indirectee);
+ }
}
/* -----------------------------------------------------------------------------
ASSERT(info->type == IND_STATIC);
if (STATIC_LINK(info,p) == NULL) {
- IF_DEBUG(gccafs, belch("CAF gc'd at 0x%04lx", (long)p));
+ IF_DEBUG(gccafs, debugBelch("CAF gc'd at 0x%04lx", (long)p));
// black hole it
SET_INFO(p,&stg_BLACKHOLE_info);
p = STATIC_LINK2(info,p);
}
- // belch("%d CAFs live", i);
+ // debugBelch("%d CAFs live", i);
}
#endif
/* -----------------------------------------------------------------------------
- Lazy black holing.
+ * Stack squeezing
+ *
+ * Code largely pinched from old RTS, then hacked to bits. We also do
+ * lazy black holing here.
+ *
+ * -------------------------------------------------------------------------- */
- 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.
- -------------------------------------------------------------------------- */
+struct stack_gap { StgWord gap_size; struct stack_gap *next_gap; };
static void
-threadLazyBlackHole(StgTSO *tso)
+stackSqueeze(StgTSO *tso, StgPtr bottom)
{
- StgUpdateFrame *update_frame;
- StgBlockingQueue *bh;
- StgPtr stack_end;
+ StgPtr frame;
+ rtsBool prev_was_update_frame;
+ StgClosure *updatee = NULL;
+ StgRetInfoTable *info;
+ StgWord current_gap_size;
+ struct stack_gap *gap;
+
+ // Stage 1:
+ // Traverse the stack upwards, replacing adjacent update frames
+ // with a single update frame and a "stack gap". A stack gap
+ // contains two values: the size of the gap, and the distance
+ // to the next gap (or the stack top).
+
+ frame = tso->sp;
+
+ ASSERT(frame < bottom);
+
+ prev_was_update_frame = rtsFalse;
+ current_gap_size = 0;
+ gap = (struct stack_gap *) (tso->sp - sizeofW(StgUpdateFrame));
- stack_end = &tso->stack[tso->stack_size];
- update_frame = tso->su;
+ while (frame < bottom) {
+
+ info = get_ret_itbl((StgClosure *)frame);
+ switch (info->i.type) {
- while (1) {
- switch (get_itbl(update_frame)->type) {
+ case UPDATE_FRAME:
+ {
+ StgUpdateFrame *upd = (StgUpdateFrame *)frame;
+
+ if (prev_was_update_frame) {
+
+ TICK_UPD_SQUEEZED();
+ /* wasn't there something about update squeezing and ticky to be
+ * sorted out? oh yes: we aren't counting each enter properly
+ * in this case. See the log somewhere. KSW 1999-04-21
+ *
+ * Check two things: that the two update frames don't point to
+ * the same object, and that the updatee_bypass isn't already an
+ * indirection. Both of these cases only happen when we're in a
+ * block hole-style loop (and there are multiple update frames
+ * on the stack pointing to the same closure), but they can both
+ * screw us up if we don't check.
+ */
+ if (upd->updatee != updatee && !closure_IND(upd->updatee)) {
+ UPD_IND_NOLOCK(upd->updatee, updatee);
+ }
- case CATCH_FRAME:
- update_frame = ((StgCatchFrame *)update_frame)->link;
- break;
+ // now mark this update frame as a stack gap. The gap
+ // marker resides in the bottom-most update frame of
+ // the series of adjacent frames, and covers all the
+ // frames in this series.
+ current_gap_size += sizeofW(StgUpdateFrame);
+ ((struct stack_gap *)frame)->gap_size = current_gap_size;
+ ((struct stack_gap *)frame)->next_gap = gap;
+
+ frame += sizeofW(StgUpdateFrame);
+ continue;
+ }
+
+ // single update frame, or the topmost update frame in a series
+ else {
+ prev_was_update_frame = rtsTrue;
+ updatee = upd->updatee;
+ frame += sizeofW(StgUpdateFrame);
+ continue;
+ }
+ }
+
+ default:
+ prev_was_update_frame = rtsFalse;
- case UPDATE_FRAME:
- bh = (StgBlockingQueue *)update_frame->updatee;
+ // we're not in a gap... check whether this is the end of a gap
+ // (an update frame can't be the end of a gap).
+ if (current_gap_size != 0) {
+ gap = (struct stack_gap *) (frame - sizeofW(StgUpdateFrame));
+ }
+ current_gap_size = 0;
- /* 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;
- }
+ frame += stack_frame_sizeW((StgClosure *)frame);
+ continue;
+ }
+ }
- if (bh->header.info != &stg_BLACKHOLE_BQ_info &&
- bh->header.info != &stg_CAF_BLACKHOLE_info) {
-#if (!defined(LAZY_BLACKHOLING)) && defined(DEBUG)
- belch("Unexpected lazy BHing required at 0x%04x",(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);
-#ifdef PROFILING
- // @LDV profiling
- // We pretend that bh has just been created.
- LDV_recordCreate(bh);
-#endif
- }
+ if (current_gap_size != 0) {
+ gap = (struct stack_gap *) (frame - sizeofW(StgUpdateFrame));
+ }
- update_frame = update_frame->link;
- break;
+ // 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:
+ //
+ // +| ********* |
+ // | ********* | <- sp
+ // | |
+ // | | <- gap_start
+ // | ......... | |
+ // | stack_gap | <- gap | chunk_size
+ // | ......... | |
+ // | ......... | <- gap_end v
+ // | ********* |
+ // | ********* |
+ // | ********* |
+ // -| ********* |
+ //
+ // 'sp' points the the current top-of-stack
+ // 'gap' points to the stack_gap structure inside the gap
+ // ***** indicates real stack data
+ // ..... indicates gap
+ // <empty> indicates unused
+ //
+ {
+ void *sp;
+ void *gap_start, *next_gap_start, *gap_end;
+ nat chunk_size;
- case SEQ_FRAME:
- update_frame = ((StgSeqFrame *)update_frame)->link;
- break;
+ next_gap_start = (void *)((unsigned char*)gap + sizeof(StgUpdateFrame));
+ sp = next_gap_start;
- case STOP_FRAME:
- return;
- default:
- barf("threadPaused");
- }
- }
-}
+ while ((StgPtr)gap > tso->sp) {
+
+ // we're working in *bytes* now...
+ gap_start = next_gap_start;
+ gap_end = (void*) ((unsigned char*)gap_start - gap->gap_size * sizeof(W_));
+
+ gap = gap->next_gap;
+ next_gap_start = (void *)((unsigned char*)gap + sizeof(StgUpdateFrame));
+
+ chunk_size = (unsigned char*)gap_end - (unsigned char*)next_gap_start;
+ sp -= chunk_size;
+ memmove(sp, next_gap_start, chunk_size);
+ }
+ tso->sp = (StgPtr)sp;
+ }
+}
/* -----------------------------------------------------------------------------
- * Stack squeezing
- *
- * Code largely pinched from old RTS, then hacked to bits. We also do
- * lazy black holing here.
- *
+ * Pausing a thread
+ *
+ * We have to prepare for GC - this means doing lazy black holing
+ * here. We also take the opportunity to do stack squeezing if it's
+ * turned on.
* -------------------------------------------------------------------------- */
-
-static void
-threadSqueezeStack(StgTSO *tso)
+void
+threadPaused(Capability *cap, StgTSO *tso)
{
- lnat displacement = 0;
- StgUpdateFrame *frame;
- StgUpdateFrame *next_frame; // Temporally next
- StgUpdateFrame *prev_frame; // Temporally previous
- StgPtr bottom;
- rtsBool prev_was_update_frame;
-#if DEBUG
- StgUpdateFrame *top_frame;
- nat upd_frames=0, stop_frames=0, catch_frames=0, seq_frames=0,
- bhs=0, squeezes=0;
- void printObj( StgClosure *obj ); // from Printer.c
-
- top_frame = tso->su;
-#endif
-
- bottom = &(tso->stack[tso->stack_size]);
- frame = tso->su;
+ 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;
- /* There must be at least one frame, namely the STOP_FRAME.
- */
- ASSERT((P_)frame < bottom);
+ while (1) {
+ // If we've already marked this frame, then stop here.
+ if (frame->header.info == (StgInfoTable *)&stg_marked_upd_frame_info) {
+ goto end;
+ }
- /* Walk down the stack, reversing the links between frames so that
- * we can walk back up as we squeeze from the bottom. Note that
- * next_frame and prev_frame refer to next and previous as they were
- * added to the stack, rather than the way we see them in this
- * walk. (It makes the next loop less confusing.)
- *
- * Stop if we find an update frame pointing to a black hole
- * (see comment in threadLazyBlackHole()).
- */
-
- next_frame = NULL;
- // bottom - sizeof(StgStopFrame) is the STOP_FRAME
- while ((P_)frame < bottom - sizeofW(StgStopFrame)) {
- prev_frame = frame->link;
- frame->link = next_frame;
- next_frame = frame;
- frame = prev_frame;
-#if DEBUG
- IF_DEBUG(sanity,
- if (!(frame>=top_frame && frame<=(StgUpdateFrame *)bottom)) {
- printObj((StgClosure *)prev_frame);
- barf("threadSqueezeStack: current frame is rubbish %p; previous was %p\n",
- frame, prev_frame);
- })
- switch (get_itbl(frame)->type) {
- case UPDATE_FRAME:
- upd_frames++;
- if (frame->updatee->header.info == &stg_BLACKHOLE_info)
- bhs++;
- break;
- case STOP_FRAME:
- stop_frames++;
- break;
- case CATCH_FRAME:
- catch_frames++;
- break;
- case SEQ_FRAME:
- seq_frames++;
- break;
- default:
- barf("Found non-frame during stack squeezing at %p (prev frame was %p)\n",
- frame, prev_frame);
- printObj((StgClosure *)prev_frame);
- }
-#endif
- if (get_itbl(frame)->type == UPDATE_FRAME
- && frame->updatee->header.info == &stg_BLACKHOLE_info) {
- break;
- }
- }
+ info = get_ret_itbl(frame);
+
+ switch (info->i.type) {
+
+ case UPDATE_FRAME:
- /* Now, we're at the bottom. Frame points to the lowest update
- * frame on the stack, and its link actually points to the frame
- * above. We have to walk back up the stack, squeezing out empty
- * update frames and turning the pointers back around on the way
- * back up.
- *
- * The bottom-most frame (the STOP_FRAME) has not been altered, and
- * we never want to eliminate it anyway. Just walk one step up
- * before starting to squeeze. When you get to the topmost frame,
- * remember that there are still some words above it that might have
- * to be moved.
- */
-
- prev_frame = frame;
- frame = next_frame;
+ SET_INFO(frame, (StgInfoTable *)&stg_marked_upd_frame_info);
- prev_was_update_frame = (get_itbl(prev_frame)->type == UPDATE_FRAME);
+ bh = ((StgUpdateFrame *)frame)->updatee;
- /*
- * Loop through all of the frames (everything except the very
- * bottom). Things are complicated by the fact that we have
- * CATCH_FRAMEs and SEQ_FRAMEs interspersed with the update frames.
- * We can only squeeze when there are two consecutive UPDATE_FRAMEs.
- */
- while (frame != NULL) {
- StgPtr sp;
- StgPtr frame_bottom = (P_)frame + sizeofW(StgUpdateFrame);
- rtsBool is_update_frame;
-
- next_frame = frame->link;
- is_update_frame = (get_itbl(frame)->type == UPDATE_FRAME);
+ 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));
- /* Check to see if
- * 1. both the previous and current frame are update frames
- * 2. the current frame is empty
- */
- if (prev_was_update_frame && is_update_frame &&
- (P_)prev_frame == frame_bottom + displacement) {
-
- // Now squeeze out the current frame
- StgClosure *updatee_keep = prev_frame->updatee;
- StgClosure *updatee_bypass = frame->updatee;
-
-#if DEBUG
- IF_DEBUG(gc, belch("@@ squeezing frame at %p", frame));
- squeezes++;
-#endif
+ // If this closure is already an indirection, then
+ // suspend the computation up to this point:
+ suspendComputation(cap,tso,(StgPtr)frame);
- /* Deal with blocking queues. If both updatees have blocked
- * threads, then we should merge the queues into the update
- * frame that we're keeping.
- *
- * Alternatively, we could just wake them up: they'll just go
- * straight to sleep on the proper blackhole! This is less code
- * and probably less bug prone, although it's probably much
- * slower --SDM
- */
-#if 0 // do it properly...
-# if (!defined(LAZY_BLACKHOLING)) && defined(DEBUG)
-# error Unimplemented lazy BH warning. (KSW 1999-01)
-# endif
- if (GET_INFO(updatee_bypass) == stg_BLACKHOLE_BQ_info
- || GET_INFO(updatee_bypass) == stg_CAF_BLACKHOLE_info
- ) {
- // Sigh. It has one. Don't lose those threads!
- if (GET_INFO(updatee_keep) == stg_BLACKHOLE_BQ_info) {
- // Urgh. Two queues. Merge them.
- P_ keep_tso = ((StgBlockingQueue *)updatee_keep)->blocking_queue;
-
- while (keep_tso->link != END_TSO_QUEUE) {
- keep_tso = keep_tso->link;
- }
- keep_tso->link = ((StgBlockingQueue *)updatee_bypass)->blocking_queue;
+ // 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;
- } else {
- // For simplicity, just swap the BQ for the BH
- P_ temp = updatee_keep;
-
- updatee_keep = updatee_bypass;
- updatee_bypass = temp;
-
- // Record the swap in the kept frame (below)
- prev_frame->updatee = updatee_keep;
- }
- }
-#endif
+ // And continue with threadPaused; there might be
+ // yet more computation to suspend.
+ threadPaused(cap,tso);
+ return;
+ }
- TICK_UPD_SQUEEZED();
- /* wasn't there something about update squeezing and ticky to be
- * sorted out? oh yes: we aren't counting each enter properly
- * in this case. See the log somewhere. KSW 1999-04-21
- *
- * Check two things: that the two update frames don't point to
- * the same object, and that the updatee_bypass isn't already an
- * indirection. Both of these cases only happen when we're in a
- * block hole-style loop (and there are multiple update frames
- * on the stack pointing to the same closure), but they can both
- * screw us up if we don't check.
- */
- if (updatee_bypass != updatee_keep && !closure_IND(updatee_bypass)) {
- // this wakes the threads up
- UPD_IND_NOLOCK(updatee_bypass, updatee_keep);
- }
-
- sp = (P_)frame - 1; // sp = stuff to slide
- displacement += sizeofW(StgUpdateFrame);
-
- } else {
- // No squeeze for this frame
- sp = frame_bottom - 1; // Keep the current frame
-
- /* Do lazy black-holing.
- */
- if (is_update_frame) {
- StgBlockingQueue *bh = (StgBlockingQueue *)frame->updatee;
- if (bh->header.info != &stg_BLACKHOLE_info &&
- bh->header.info != &stg_BLACKHOLE_BQ_info &&
- bh->header.info != &stg_CAF_BLACKHOLE_info) {
+ if (bh->header.info != &stg_CAF_BLACKHOLE_info) {
#if (!defined(LAZY_BLACKHOLING)) && defined(DEBUG)
- belch("Unexpected lazy BHing required at 0x%04x",(int)bh);
+ debugBelch("Unexpected lazy BHing required at 0x%04lx\n",(long)bh);
#endif
-#ifdef DEBUG
- /* zero out the slop so that the sanity checker can tell
- * where the next closure is.
- */
- {
- StgInfoTable *info = get_itbl(bh);
- nat np = info->layout.payload.ptrs, nw = 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 (info->type != THUNK_SELECTOR) {
- for (i = np; i < np + nw; i++) {
- ((StgClosure *)bh)->payload[i] = 0;
- }
- }
- }
-#endif
-#ifdef PROFILING
- // @LDV profiling
- // We pretend that bh is now dead.
- LDV_recordDead_FILL_SLOP_DYNAMIC((StgClosure *)bh);
-#endif
- //
- // Todo: maybe use SET_HDR() and remove LDV_recordCreate()?
- //
- SET_INFO(bh,&stg_BLACKHOLE_info);
+ // 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 has just been created.
- LDV_recordCreate(bh);
+ // @LDV profiling
+ // We pretend that bh is now dead.
+ LDV_recordDead_FILL_SLOP_DYNAMIC((StgClosure *)bh);
#endif
- }
- }
+ SET_INFO(bh,&stg_BLACKHOLE_info);
- // Fix the link in the current frame (should point to the frame below)
- frame->link = prev_frame;
- prev_was_update_frame = is_update_frame;
+ // 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;
+ }
+ }
}
-
- // Now slide all words from sp up to the next frame
-
- if (displacement > 0) {
- P_ next_frame_bottom;
- if (next_frame != NULL)
- next_frame_bottom = (P_)next_frame + sizeofW(StgUpdateFrame);
- else
- next_frame_bottom = tso->sp - 1;
-
-#if 0
- IF_DEBUG(gc,
- belch("sliding [%p, %p] by %ld", sp, next_frame_bottom,
- displacement))
-#endif
-
- while (sp >= next_frame_bottom) {
- sp[displacement] = *sp;
- sp -= 1;
- }
+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);
}
- (P_)prev_frame = (P_)frame + displacement;
- frame = next_frame;
- }
-
- tso->sp += displacement;
- tso->su = prev_frame;
-#if 0
- IF_DEBUG(gc,
- belch("@@ threadSqueezeStack: squeezed %d update-frames; found %d BHs; found %d update-, %d stop-, %d catch, %d seq-frames",
- squeezes, bhs, upd_frames, stop_frames, catch_frames, seq_frames))
-#endif
-}
-
-
-/* -----------------------------------------------------------------------------
- * Pausing a thread
- *
- * We have to prepare for GC - this means doing lazy black holing
- * here. We also take the opportunity to do stack squeezing if it's
- * turned on.
- * -------------------------------------------------------------------------- */
-void
-threadPaused(StgTSO *tso)
-{
- if ( RtsFlags.GcFlags.squeezeUpdFrames == rtsTrue )
- threadSqueezeStack(tso); // does black holing too
- else
- threadLazyBlackHole(tso);
}
/* -----------------------------------------------------------------------------
#if DEBUG
void
-printMutOnceList(generation *gen)
-{
- StgMutClosure *p, *next;
-
- p = gen->mut_once_list;
- next = p->mut_link;
-
- fprintf(stderr, "@@ Mut once list %p: ", gen->mut_once_list);
- for (; p != END_MUT_LIST; p = next, next = p->mut_link) {
- fprintf(stderr, "%p (%s), ",
- p, info_type((StgClosure *)p));
- }
- fputc('\n', stderr);
-}
-
-void
printMutableList(generation *gen)
{
- StgMutClosure *p, *next;
+ bdescr *bd;
+ StgPtr p;
- p = gen->mut_list;
- next = p->mut_link;
+ debugBelch("@@ Mutable list %p: ", gen->mut_list);
- fprintf(stderr, "@@ Mutable list %p: ", gen->mut_list);
- for (; p != END_MUT_LIST; p = next, next = p->mut_link) {
- fprintf(stderr, "%p (%s), ",
- p, info_type((StgClosure *)p));
- }
- fputc('\n', stderr);
-}
-
-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 == TSO ||
- info->type == ARR_WORDS);
+ for (bd = gen->mut_list; bd != NULL; bd = bd->link) {
+ for (p = bd->start; p < bd->free; p++) {
+ debugBelch("%p (%s), ", (void *)*p, info_type((StgClosure *)*p));
+ }
+ }
+ debugBelch("\n");
}
-
-
-#endif // DEBUG
+#endif /* DEBUG */
projects / ghc-hetmet.git / blobdiff