+++ /dev/null
-/* -----------------------------------------------------------------------------
- *
- * (c) The GHC Team 1998-2003
- *
- * Generational garbage collector
- *
- * ---------------------------------------------------------------------------*/
-
-#include "PosixSource.h"
-#include "Rts.h"
-#include "RtsFlags.h"
-#include "RtsUtils.h"
-#include "Apply.h"
-#include "OSThreads.h"
-#include "Storage.h"
-#include "LdvProfile.h"
-#include "Updates.h"
-#include "Stats.h"
-#include "Schedule.h"
-#include "Sanity.h"
-#include "BlockAlloc.h"
-#include "MBlock.h"
-#include "ProfHeap.h"
-#include "SchedAPI.h"
-#include "Weak.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"
-# include "FetchMe.h"
-# if defined(DEBUG)
-# include "Printer.h"
-# include "ParallelDebug.h"
-# endif
-#endif
-#include "HsFFI.h"
-#include "Linker.h"
-#if defined(RTS_GTK_FRONTPANEL)
-#include "FrontPanel.h"
-#endif
-#include "Trace.h"
-#include "RetainerProfile.h"
-#include "RaiseAsync.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.
- *
- * During GC:
- * We maintain a linked list of static objects that are still live.
- * The requirements for this list are:
- *
- * - we need to scan the list while adding to it, in order to
- * scavenge all the static objects (in the same way that
- * breadth-first scavenging works for dynamic objects).
- *
- * - we need to be able to tell whether an object is already on
- * the list, to break loops.
- *
- * Each static object has a "static link field", which we use for
- * linking objects on to the list. We use a stack-type list, consing
- * objects on the front as they are added (this means that the
- * scavenge phase is depth-first, not breadth-first, but that
- * shouldn't matter).
- *
- * A separate list is kept for objects that have been scavenged
- * already - this is so that we can zero all the marks afterwards.
- *
- * An object is on the list if its static link field is non-zero; this
- * means that we have to mark the end of the list with '1', not NULL.
- *
- * Extra notes for generational GC:
- *
- * Each generation has a static object list associated with it. When
- * collecting generations up to N, we treat the static object lists
- * from generations > N as roots.
- *
- * We build up a static object list while collecting generations 0..N,
- * which is then appended to the static object list of generation N+1.
- */
-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
- * flag) is when we're collecting all generations. We only attempt to
- * deal with static objects and GC CAFs when doing a major GC.
- */
-static nat N;
-static rtsBool major_gc;
-
-/* Youngest generation that objects should be evacuated to in
- * evacuate(). (Logically an argument to evacuate, but it's static
- * a lot of the time so we optimise it into a global variable).
- */
-static nat evac_gen;
-
-/* Whether to do eager promotion or not.
- */
-static rtsBool eager_promotion;
-
-/* Weak pointers
- */
-StgWeak *old_weak_ptr_list; // also pending finaliser list
-
-/* 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;
-StgTSO *resurrected_threads;
-
-/* Flag indicating failure to evacuate an object to the desired
- * generation.
- */
-static rtsBool failed_to_evac;
-
-/* Saved nursery (used for 2-space collector only)
- */
-static bdescr *saved_nursery;
-static nat saved_n_blocks;
-
-/* Data used for allocation area sizing.
- */
-static lnat new_blocks; // blocks allocated during this GC
-static lnat new_scavd_blocks; // ditto, but depth-first blocks
-static lnat g0s0_pcnt_kept = 30; // percentage of g0s0 live at last minor GC
-
-/* Used to avoid long recursion due to selector thunks
- */
-static lnat thunk_selector_depth = 0;
-#define MAX_THUNK_SELECTOR_DEPTH 8
-
-/* Mut-list stats */
-#ifdef DEBUG
-static nat
- mutlist_MUTVARS,
- mutlist_MUTARRS,
- mutlist_OTHERS;
-#endif
-
-/* -----------------------------------------------------------------------------
- Static function declarations
- -------------------------------------------------------------------------- */
-
-static bdescr * gc_alloc_block ( step *stp );
-static void mark_root ( StgClosure **root );
-
-// 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 rtsBool traverse_weak_ptr_list ( void );
-static void mark_weak_ptr_list ( StgWeak **list );
-static rtsBool traverse_blackhole_queue ( void );
-
-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 );
-#endif
-
-/* -----------------------------------------------------------------------------
- inline functions etc. for dealing with the mark bitmap & stack.
- -------------------------------------------------------------------------- */
-
-#define MARK_STACK_BLOCKS 4
-
-static bdescr *mark_stack_bdescr;
-static StgPtr *mark_stack;
-static StgPtr *mark_sp;
-static StgPtr *mark_splim;
-
-// Flag and pointers used for falling back to a linear scan when the
-// mark stack overflows.
-static rtsBool mark_stack_overflowed;
-static bdescr *oldgen_scan_bd;
-static StgPtr oldgen_scan;
-
-STATIC_INLINE rtsBool
-mark_stack_empty(void)
-{
- return mark_sp == mark_stack;
-}
-
-STATIC_INLINE rtsBool
-mark_stack_full(void)
-{
- return mark_sp >= mark_splim;
-}
-
-STATIC_INLINE void
-reset_mark_stack(void)
-{
- mark_sp = mark_stack;
-}
-
-STATIC_INLINE void
-push_mark_stack(StgPtr p)
-{
- *mark_sp++ = p;
-}
-
-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
-
- 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 generations (mutable_list).
-
- - for each pointer, evacuate the object it points to into either
-
- + 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
-GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc )
-{
- bdescr *bd;
- step *stp;
- lnat live, allocated, copied = 0, scavd_copied = 0;
- lnat oldgen_saved_blocks = 0;
- nat g, s, i;
-
- ACQUIRE_SM_LOCK;
-
-#ifdef PROFILING
- CostCentreStack *prev_CCS;
-#endif
-
- debugTrace(DEBUG_gc, "starting GC");
-
-#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();
-
- // attribute any costs to CCS_GC
-#ifdef PROFILING
- prev_CCS = CCCS;
- CCCS = CCS_GC;
-#endif
-
- /* Approximate how much we allocated.
- * Todo: only when generating stats?
- */
- allocated = calcAllocated();
-
- /* Figure out which generation to collect
- */
- if (force_major_gc) {
- N = RtsFlags.GcFlags.generations - 1;
- major_gc = rtsTrue;
- } else {
- N = 0;
- for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
- if (generations[g].steps[0].n_blocks +
- generations[g].steps[0].n_large_blocks
- >= generations[g].max_blocks) {
- N = g;
- }
- }
- major_gc = (N == RtsFlags.GcFlags.generations-1);
- }
-
-#ifdef RTS_GTK_FRONTPANEL
- if (RtsFlags.GcFlags.frontpanel) {
- updateFrontPanelBeforeGC(N);
- }
-#endif
-
- // check stack sanity *before* GC (ToDo: check all threads)
-#if defined(GRAN)
- // ToDo!: check sanity IF_DEBUG(sanity, checkTSOsSanity());
-#endif
- IF_DEBUG(sanity, checkFreeListSanity());
-
- /* Initialise the static object lists
- */
- static_objects = END_OF_STATIC_LIST;
- scavenged_static_objects = END_OF_STATIC_LIST;
-
- /* 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) {
- 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.
- //
- for (g = 0; g <= N; g++) {
-
- // 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++) {
-
- // generation 0, step 0 doesn't need to-space
- if (g == 0 && s == 0 && RtsFlags.GcFlags.generations > 1) {
- continue;
- }
-
- stp = &generations[g].steps[s];
- ASSERT(stp->gen_no == g);
-
- // 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;
-
- // mark the large objects as not evacuated yet
- for (bd = stp->large_objects; bd; bd = bd->link) {
- bd->flags &= ~BF_EVACUATED;
- }
-
- // for a compacted step, we need to allocate the bitmap
- if (stp->is_compacted) {
- nat bitmap_size; // in bytes
- bdescr *bitmap_bdescr;
- StgWord *bitmap;
-
- bitmap_size = stp->n_old_blocks * BLOCK_SIZE / (sizeof(W_)*BITS_PER_BYTE);
-
- if (bitmap_size > 0) {
- bitmap_bdescr = allocGroup((lnat)BLOCK_ROUND_UP(bitmap_size)
- / BLOCK_SIZE);
- stp->bitmap = bitmap_bdescr;
- bitmap = bitmap_bdescr->start;
-
- debugTrace(DEBUG_gc, "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
- // block descriptor.
- 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).
- */
- 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 = gc_alloc_block(stp);
- stp->blocks = bd;
- stp->n_blocks = 1;
- }
- if (stp->scavd_hp == NULL) {
- gc_alloc_scavd_block(stp);
- stp->n_blocks++;
- }
- /* Set the scan pointer for older generations: remember we
- * still have to scavenge objects that have been promoted. */
- stp->scan = stp->hp;
- stp->scan_bd = stp->hp_bd;
- stp->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.
- */
- if (major_gc) {
- mark_stack_bdescr = allocGroup(MARK_STACK_BLOCKS);
- mark_stack = (StgPtr *)mark_stack_bdescr->start;
- mark_sp = mark_stack;
- mark_splim = mark_stack + (MARK_STACK_BLOCKS * BLOCK_SIZE_W);
- } else {
- mark_stack_bdescr = NULL;
- }
-
- eager_promotion = rtsTrue; // for now
-
- /* -----------------------------------------------------------------------
- * follow all the roots that we know about:
- * - mutable lists from each generation > N
- * we want to *scavenge* these roots, not evacuate them: they're not
- * going to move in this GC.
- * Also: do them in reverse generation order. This is because we
- * often want to promote objects that are pointed to by older
- * generations early, so we don't have to repeatedly copy them.
- * Doing the generations in reverse order ensures that we don't end
- * up in the situation where we want to evac an object to gen 3 and
- * it has already been evaced to gen 2.
- */
- {
- int st;
- for (g = RtsFlags.GcFlags.generations-1; g > N; g--) {
- generations[g].saved_mut_list = generations[g].mut_list;
- generations[g].mut_list = 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]));
- scavenge_mutable_list(&generations[g]);
- evac_gen = g;
- for (st = generations[g].n_steps-1; st >= 0; st--) {
- scavenge(&generations[g].steps[st]);
- }
- }
- }
-
- /* follow roots from the CAF list (used by GHCi)
- */
- evac_gen = 0;
- markCAFs(mark_root);
-
- /* follow all the roots that the application knows about.
- */
- evac_gen = 0;
- get_roots(mark_root);
-
-#if defined(PAR)
- /* And don't forget to mark the TSO if we got here direct from
- * Haskell! */
- /* Not needed in a seq version?
- if (CurrentTSO) {
- CurrentTSO = (StgTSO *)MarkRoot((StgClosure *)CurrentTSO);
- }
- */
-
- // Mark the entries in the GALA table of the parallel system
- markLocalGAs(major_gc);
- // Mark all entries on the list of pending fetches
- markPendingFetches(major_gc);
-#endif
-
- /* Mark the weak pointer list, and prepare to detect dead weak
- * pointers.
- */
- mark_weak_ptr_list(&weak_ptr_list);
- old_weak_ptr_list = weak_ptr_list;
- weak_ptr_list = NULL;
- weak_stage = WeakPtrs;
-
- /* The all_threads list is like the weak_ptr_list.
- * See traverse_weak_ptr_list() for the details.
- */
- old_all_threads = all_threads;
- all_threads = END_TSO_QUEUE;
- resurrected_threads = END_TSO_QUEUE;
-
- /* Mark the stable pointer table.
- */
- markStablePtrTable(mark_root);
-
- /* Mark the root pointer table.
- */
- markRootPtrTable(mark_root);
-
- /* -------------------------------------------------------------------------
- * Repeatedly scavenge all the areas we know about until there's no
- * more scavenging to be done.
- */
- {
- rtsBool flag;
- loop:
- flag = rtsFalse;
-
- // scavenge static objects
- if (major_gc && static_objects != END_OF_STATIC_LIST) {
- IF_DEBUG(sanity, checkStaticObjects(static_objects));
- scavenge_static();
- }
-
- /* When scavenging the older generations: Objects may have been
- * evacuated from generations <= N into older generations, and we
- * need to scavenge these objects. We're going to try to ensure that
- * any evacuations that occur move the objects into at least the
- * same generation as the object being scavenged, otherwise we
- * have to create new entries on the mutable list for the older
- * generation.
- */
-
- // scavenge each step in generations 0..maxgen
- {
- long gen;
- int st;
-
- loop2:
- // scavenge objects in compacted generation
- if (mark_stack_overflowed || oldgen_scan_bd != NULL ||
- (mark_stack_bdescr != NULL && !mark_stack_empty())) {
- scavenge_mark_stack();
- flag = rtsTrue;
- }
-
- for (gen = RtsFlags.GcFlags.generations; --gen >= 0; ) {
- for (st = generations[gen].n_steps; --st >= 0; ) {
- if (gen == 0 && st == 0 && RtsFlags.GcFlags.generations > 1) {
- continue;
- }
- stp = &generations[gen].steps[st];
- evac_gen = gen;
- if (stp->hp_bd != stp->scan_bd || stp->scan < stp->hp) {
- scavenge(stp);
- flag = rtsTrue;
- goto loop2;
- }
- if (stp->new_large_objects != NULL) {
- scavenge_large(stp);
- flag = rtsTrue;
- goto loop2;
- }
- }
- }
- }
-
- // if any blackholes are alive, make the threads that wait on
- // them alive too.
- if (traverse_blackhole_queue())
- flag = rtsTrue;
-
- if (flag) { goto loop; }
-
- // 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);
- IF_DEBUG(sanity, checkLAGAtable(rtsTrue/*check closures, too*/));
-#endif
-
- // Now see which stable names are still alive.
- gcStablePtrTable();
-
- // Tidy the end of the to-space chains
- for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
- 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;
- Bdescr(stp->scavd_hp)->free = stp->scavd_hp;
- }
- }
- }
-
-#ifdef PROFILING
- // We call processHeapClosureForDead() on every closure destroyed during
- // the current garbage collection, so we invoke LdvCensusForDead().
- if (RtsFlags.ProfFlags.doHeapProfile == HEAP_BY_LDV
- || RtsFlags.ProfFlags.bioSelector != NULL)
- LdvCensusForDead(N);
-#endif
-
- // NO MORE EVACUATION AFTER THIS POINT!
- // 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_old_blocks;
- compact(get_roots);
- }
-
- IF_DEBUG(sanity, checkGlobalTSOList(rtsFalse));
-
- /* 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;
-
- debugTrace(DEBUG_gc,
- "mut_list_size: %lu (%d vars, %d arrays, %d others)",
- (unsigned long)(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 == 0 && s == 0 && RtsFlags.GcFlags.generations > 1)) {
- // stats information: how much we copied
- 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) {
-
- /* free old memory and shift to-space into from-space for all
- * the collected steps (except the allocation area). These
- * freed blocks will probaby be quickly recycled.
- */
- if (!(g == 0 && s == 0)) {
- 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->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->old_blocks != NULL) {
- for (bd = stp->old_blocks; bd != NULL; bd = next) {
- // NB. this step might not be compacted next
- // time, so reset the BF_COMPACTED flags.
- // They are set before GC if we're going to
- // compact. (search for BF_COMPACTED above).
- bd->flags &= ~BF_COMPACTED;
- next = bd->link;
- if (next == NULL) {
- bd->link = stp->blocks;
- }
- }
- stp->blocks = stp->old_blocks;
- }
- // add the new blocks to the block tally
- stp->n_blocks += stp->n_old_blocks;
- ASSERT(countBlocks(stp->blocks) == stp->n_blocks);
- } else {
- freeChain(stp->old_blocks);
- for (bd = stp->blocks; bd != NULL; bd = bd->link) {
- bd->flags &= ~BF_EVACUATED; // now from-space
- }
- }
- stp->old_blocks = NULL;
- stp->n_old_blocks = 0;
- }
-
- /* LARGE OBJECTS. The current live large objects are chained on
- * scavenged_large, having been moved during garbage
- * collection from large_objects. Any objects left on
- * large_objects list are therefore dead, so we free them here.
- */
- for (bd = stp->large_objects; bd != NULL; bd = next) {
- next = bd->link;
- freeGroup(bd);
- bd = next;
- }
-
- // update the count of blocks used by large objects
- for (bd = stp->scavenged_large_objects; bd != NULL; bd = bd->link) {
- bd->flags &= ~BF_EVACUATED;
- }
- stp->large_objects = stp->scavenged_large_objects;
- stp->n_large_blocks = stp->n_scavenged_large_blocks;
-
- } else {
- // for older generations...
-
- /* For older generations, we need to append the
- * scavenged_large_object list (i.e. large objects that have been
- * promoted during this GC) to the large_object list for that step.
- */
- for (bd = stp->scavenged_large_objects; bd; bd = next) {
- next = bd->link;
- bd->flags &= ~BF_EVACUATED;
- dbl_link_onto(bd, &stp->large_objects);
- }
-
- // add the new blocks we promoted during this GC
- stp->n_large_blocks += stp->n_scavenged_large_blocks;
- }
- }
- }
-
- /* Reset the sizes of the older generations when we do a major
- * collection.
- *
- * CURRENT STRATEGY: make all generations except zero the same size.
- * We have to stay within the maximum heap size, and leave a certain
- * percentage of the maximum heap size available to allocate into.
- */
- if (major_gc && RtsFlags.GcFlags.generations > 1) {
- nat live, size, min_alloc;
- nat max = RtsFlags.GcFlags.maxHeapSize;
- nat gens = RtsFlags.GcFlags.generations;
-
- // live in the oldest generations
- live = oldest_gen->steps[0].n_blocks +
- oldest_gen->steps[0].n_large_blocks;
-
- // default max size for all generations except zero
- size = stg_max(live * RtsFlags.GcFlags.oldGenFactor,
- RtsFlags.GcFlags.minOldGenSize);
-
- // minimum size for generation zero
- min_alloc = stg_max((RtsFlags.GcFlags.pcFreeHeap * max) / 200,
- RtsFlags.GcFlags.minAllocAreaSize);
-
- // Auto-enable compaction when the residency reaches a
- // certain percentage of the maximum heap size (default: 30%).
- if (RtsFlags.GcFlags.generations > 1 &&
- (RtsFlags.GcFlags.compact ||
- (max > 0 &&
- oldest_gen->steps[0].n_blocks >
- (RtsFlags.GcFlags.compactThreshold * max) / 100))) {
- oldest_gen->steps[0].is_compacted = 1;
-// debugBelch("compaction: on\n", live);
- } else {
- oldest_gen->steps[0].is_compacted = 0;
-// debugBelch("compaction: off\n", live);
- }
-
- // if we're going to go over the maximum heap size, reduce the
- // size of the generations accordingly. The calculation is
- // different if compaction is turned on, because we don't need
- // to double the space required to collect the old generation.
- if (max != 0) {
-
- // this test is necessary to ensure that the calculations
- // below don't have any negative results - we're working
- // with unsigned values here.
- if (max < min_alloc) {
- heapOverflow();
- }
-
- if (oldest_gen->steps[0].is_compacted) {
- if ( (size + (size - 1) * (gens - 2) * 2) + min_alloc > max ) {
- size = (max - min_alloc) / ((gens - 1) * 2 - 1);
- }
- } else {
- if ( (size * (gens - 1) * 2) + min_alloc > max ) {
- size = (max - min_alloc) / ((gens - 1) * 2);
- }
- }
-
- if (size < live) {
- heapOverflow();
- }
- }
-
-#if 0
- debugBelch("live: %d, min_alloc: %d, size : %d, max = %d\n", live,
- min_alloc, size, max);
-#endif
-
- for (g = 0; g < gens; g++) {
- generations[g].max_blocks = size;
- }
- }
-
- // Guess the amount of live data for stats.
- live = calcLive();
-
- /* Free the small objects allocated via allocate(), since this will
- * all have been copied into G0S1 now.
- */
- if (small_alloc_list != NULL) {
- freeChain(small_alloc_list);
- }
- small_alloc_list = NULL;
- alloc_blocks = 0;
- alloc_Hp = NULL;
- alloc_HpLim = NULL;
- alloc_blocks_lim = RtsFlags.GcFlags.minAllocAreaSize;
-
- // Start a new pinned_object_block
- pinned_object_block = NULL;
-
- /* Free the mark stack.
- */
- if (mark_stack_bdescr != NULL) {
- freeGroup(mark_stack_bdescr);
- }
-
- /* Free any bitmaps.
- */
- for (g = 0; g <= N; g++) {
- for (s = 0; s < generations[g].n_steps; s++) {
- stp = &generations[g].steps[s];
- if (stp->bitmap != NULL) {
- freeGroup(stp->bitmap);
- stp->bitmap = NULL;
- }
- }
- }
-
- /* Two-space collector:
- * Free the old to-space, and estimate the amount of live data.
- */
- if (RtsFlags.GcFlags.generations == 1) {
- nat blocks;
-
- if (g0s0->old_blocks != NULL) {
- freeChain(g0s0->old_blocks);
- }
- 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. */
-
- /* set up a new nursery. Allocate a nursery size based on a
- * function of the amount of live data (by default a factor of 2)
- * Use the blocks from the old nursery if possible, freeing up any
- * left over blocks.
- *
- * If we get near the maximum heap size, then adjust our nursery
- * size accordingly. If the nursery is the same size as the live
- * data (L), then we need 3L bytes. We can reduce the size of the
- * nursery to bring the required memory down near 2L bytes.
- *
- * A normal 2-space collector would need 4L bytes to give the same
- * performance we get from 3L bytes, reducing to the same
- * performance at 2L bytes.
- */
- blocks = g0s0->n_old_blocks;
-
- if ( RtsFlags.GcFlags.maxHeapSize != 0 &&
- blocks * RtsFlags.GcFlags.oldGenFactor * 2 >
- RtsFlags.GcFlags.maxHeapSize ) {
- long adjusted_blocks; // signed on purpose
- int pc_free;
-
- adjusted_blocks = (RtsFlags.GcFlags.maxHeapSize - 2 * blocks);
-
- debugTrace(DEBUG_gc, "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 = adjusted_blocks;
-
- } else {
- blocks *= RtsFlags.GcFlags.oldGenFactor;
- if (blocks < RtsFlags.GcFlags.minAllocAreaSize) {
- blocks = RtsFlags.GcFlags.minAllocAreaSize;
- }
- }
- resizeNurseries(blocks);
-
- } else {
- /* Generational collector:
- * If the user has given us a suggested heap size, adjust our
- * allocation area to make best use of the memory available.
- */
-
- if (RtsFlags.GcFlags.heapSizeSuggestion) {
- long blocks;
- nat needed = calcNeeded(); // approx blocks needed at next GC
-
- /* Guess how much will be live in generation 0 step 0 next time.
- * A good approximation is obtained by finding the
- * percentage of g0s0 that was live at the last minor GC.
- */
- if (N == 0) {
- g0s0_pcnt_kept = (new_blocks * 100) / countNurseryBlocks();
- }
-
- /* Estimate a size for the allocation area based on the
- * information available. We might end up going slightly under
- * or over the suggested heap size, but we should be pretty
- * close on average.
- *
- * Formula: suggested - needed
- * ----------------------------
- * 1 + g0s0_pcnt_kept/100
- *
- * where 'needed' is the amount of memory needed at the next
- * collection for collecting all steps except g0s0.
- */
- blocks =
- (((long)RtsFlags.GcFlags.heapSizeSuggestion - (long)needed) * 100) /
- (100 + (long)g0s0_pcnt_kept);
-
- if (blocks < (long)RtsFlags.GcFlags.minAllocAreaSize) {
- blocks = RtsFlags.GcFlags.minAllocAreaSize;
- }
-
- resizeNurseries((nat)blocks);
-
- } else {
- // we might have added extra large blocks to the nursery, so
- // resize back to minAllocAreaSize again.
- resizeNurseriesFixed(RtsFlags.GcFlags.minAllocAreaSize);
- }
- }
-
- // mark the garbage collected CAFs as dead
-#if 0 && defined(DEBUG) // doesn't work at the moment
- if (major_gc) { gcCAFs(); }
-#endif
-
-#ifdef PROFILING
- // resetStaticObjectForRetainerProfiling() must be called before
- // zeroing below.
- resetStaticObjectForRetainerProfiling();
-#endif
-
- // zero the scavenged static object list
- if (major_gc) {
- zero_static_object_list(scavenged_static_objects);
- }
-
- // Reset the nursery
- resetNurseries();
-
- // start any pending finalizers
- 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);
-
- // check sanity after GC
- IF_DEBUG(sanity, checkSanity());
-
- // extra GC trace info
- IF_DEBUG(gc, statDescribeGens());
-
-#ifdef DEBUG
- // symbol-table based profiling
- /* heapCensus(to_blocks); */ /* ToDo */
-#endif
-
- // restore enclosing cost centre
-#ifdef PROFILING
- CCCS = prev_CCS;
-#endif
-
-#ifdef DEBUG
- // check for memory leaks if DEBUG is on
- memInventory();
-#endif
-
-#ifdef RTS_GTK_FRONTPANEL
- if (RtsFlags.GcFlags.frontpanel) {
- updateFrontPanelAfterGC( N, live );
- }
-#endif
-
- // ok, GC over: tell the stats department what happened.
- stat_endGC(allocated, live, copied, scavd_copied, N);
-
-#if defined(RTS_USER_SIGNALS)
- // unblock signals again
- unblockUserSignals();
-#endif
-
- RELEASE_SM_LOCK;
-
- //PAR_TICKY_TP();
-}
-
-
-/* -----------------------------------------------------------------------------
- Weak Pointers
-
- traverse_weak_ptr_list is called possibly many times during garbage
- collection. It returns a flag indicating whether it did any work
- (i.e. called evacuate on any live pointers).
-
- Invariant: traverse_weak_ptr_list is called when the heap is in an
- idempotent state. That means that there are no pending
- evacuate/scavenge operations. This invariant helps the weak
- pointer code decide which weak pointers are dead - if there are no
- new live weak pointers, then all the currently unreachable ones are
- dead.
-
- For generational GC: we just don't try to finalize weak pointers in
- older generations than the one we're collecting. This could
- probably be optimised by keeping per-generation lists of weak
- pointers, but for a few weak pointers this scheme will work.
-
- 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
-traverse_weak_ptr_list(void)
-{
- StgWeak *w, **last_w, *next_w;
- StgClosure *new;
- rtsBool flag = rtsFalse;
-
- switch (weak_stage) {
-
- 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) {
-
- case EVACUATED:
- next_w = (StgWeak *)((StgEvacuated *)w)->evacuee;
- *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;
-
- debugTrace(DEBUG_weak,
- "weak pointer still alive at %p -> %p",
- w, w->key);
- continue;
- }
- else {
- last_w = &(w->link);
- next_w = w->link;
- continue;
- }
-
- 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);
- }
-
- // Next, move to the WeakThreads stage after fully
- // scavenging the finalizers we've just evacuated.
- weak_stage = WeakThreads;
- }
-
- return rtsTrue;
-
- 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:
- ;
- }
-
- 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;
-
- /* 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;
- }
- }
-
- /* Finally, we can update the blackhole_queue. This queue
- * simply strings together TSOs blocked on black holes, it is
- * not intended to keep anything alive. Hence, we do not follow
- * pointers on the blackhole_queue until now, when we have
- * determined which TSOs are otherwise reachable. We know at
- * this point that all TSOs have been evacuated, however.
- */
- {
- StgTSO **pt;
- for (pt = &blackhole_queue; *pt != END_TSO_QUEUE; pt = &((*pt)->link)) {
- *pt = (StgTSO *)isAlive((StgClosure *)*pt);
- ASSERT(*pt != NULL);
- }
- }
-
- weak_stage = WeakDone; // *now* we're done,
- return rtsTrue; // but one more round of scavenging, please
-
- default:
- barf("traverse_weak_ptr_list");
- return rtsTrue;
- }
-
-}
-
-/* -----------------------------------------------------------------------------
- The blackhole queue
-
- Threads on this list behave like weak pointers during the normal
- phase of garbage collection: if the blackhole is reachable, then
- the thread is reachable too.
- -------------------------------------------------------------------------- */
-static rtsBool
-traverse_blackhole_queue (void)
-{
- StgTSO *prev, *t, *tmp;
- rtsBool flag;
-
- flag = rtsFalse;
- prev = NULL;
-
- for (t = blackhole_queue; t != END_TSO_QUEUE; prev=t, t = t->link) {
- if (! (tmp = (StgTSO *)isAlive((StgClosure*)t))) {
- if (isAlive(t->block_info.closure)) {
- t = (StgTSO *)evacuate((StgClosure *)t);
- if (prev) prev->link = t;
- flag = rtsTrue;
- }
- }
- }
- return flag;
-}
-
-/* -----------------------------------------------------------------------------
- After GC, the live weak pointer list may have forwarding pointers
- on it, because a weak pointer object was evacuated after being
- moved to the live weak pointer list. We remove those forwarding
- pointers here.
-
- Also, we don't consider weak pointer objects to be reachable, but
- we must nevertheless consider them to be "live" and retain them.
- Therefore any weak pointer objects which haven't as yet been
- evacuated need to be evacuated now.
- -------------------------------------------------------------------------- */
-
-
-static void
-mark_weak_ptr_list ( StgWeak **list )
-{
- StgWeak *w, **last_w;
-
- last_w = list;
- for (w = *list; w; w = w->link) {
- // 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);
- }
-}
-
-/* -----------------------------------------------------------------------------
- isAlive determines whether the given closure is still alive (after
- a garbage collection) or not. It returns the new address of the
- closure if it is alive, or NULL otherwise.
-
- NOTE: Use it before compaction only!
- -------------------------------------------------------------------------- */
-
-
-StgClosure *
-isAlive(StgClosure *p)
-{
- const StgInfoTable *info;
- bdescr *bd;
-
- while (1) {
-
- ASSERT(LOOKS_LIKE_CLOSURE_PTR(p));
- info = get_itbl(p);
-
- // 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;
- }
-
- // ignore closures in generations that we're not collecting.
- 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 use the evacuated flag
- if (bd->flags & BF_LARGE) {
- return NULL;
- }
-
- // check the mark bit for compacted steps
- if ((bd->flags & BF_COMPACTED) && is_marked((P_)p,bd)) {
- return p;
- }
-
- switch (info->type) {
-
- case IND:
- case IND_STATIC:
- case IND_PERM:
- case IND_OLDGEN: // rely on compatible layout with StgInd
- case IND_OLDGEN_PERM:
- // follow indirections
- p = ((StgInd *)p)->indirectee;
- continue;
-
- case EVACUATED:
- // alive!
- return ((StgEvacuated *)p)->evacuee;
-
- case TSO:
- if (((StgTSO *)p)->what_next == ThreadRelocated) {
- p = (StgClosure *)((StgTSO *)p)->link;
- continue;
- }
- return NULL;
-
- default:
- // dead.
- return NULL;
- }
- }
-}
-
-static void
-mark_root(StgClosure **root)
-{
- *root = evacuate(*root);
-}
-
-STATIC_INLINE void
-upd_evacuee(StgClosure *p, StgClosure *dest)
-{
- // not true: (ToDo: perhaps it should be)
- // ASSERT(Bdescr((P_)dest)->flags & BF_EVACUATED);
- SET_INFO(p, &stg_EVACUATED_info);
- ((StgEvacuated *)p)->evacuee = dest;
-}
-
-
-STATIC_INLINE StgClosure *
-copy(StgClosure *src, nat size, step *stp)
-{
- StgPtr to, from;
- nat i;
-#ifdef PROFILING
- // @LDV profiling
- nat size_org = size;
-#endif
-
- TICK_GC_WORDS_COPIED(size);
- /* Find out where we're going, using the handy "to" pointer in
- * the step of the source object. If it turns out we need to
- * evacuate to an older generation, adjust it here (see comment
- * by evacuate()).
- */
- if (stp->gen_no < evac_gen) {
- if (eager_promotion) {
- stp = &generations[evac_gen].steps[0];
- } else {
- failed_to_evac = rtsTrue;
- }
- }
-
- /* chain a new block onto the to-space for the destination step if
- * necessary.
- */
- if (stp->hp + size >= stp->hpLim) {
- gc_alloc_block(stp);
- }
-
- to = stp->hp;
- from = (StgPtr)src;
- stp->hp = to + size;
- for (i = 0; i < size; i++) { // unroll for small i
- to[i] = from[i];
- }
- 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;
-}
-
-// Same as copy() above, except the object will be allocated in memory
-// that will not be scavenged. Used for object that have no pointer
-// fields.
-STATIC_INLINE StgClosure *
-copy_noscav(StgClosure *src, nat size, step *stp)
-{
- StgPtr to, from;
- nat i;
-#ifdef PROFILING
- // @LDV profiling
- nat size_org = size;
-#endif
-
- TICK_GC_WORDS_COPIED(size);
- /* Find out where we're going, using the handy "to" pointer in
- * the step of the source object. If it turns out we need to
- * evacuate to an older generation, adjust it here (see comment
- * by evacuate()).
- */
- if (stp->gen_no < evac_gen) {
- if (eager_promotion) {
- stp = &generations[evac_gen].steps[0];
- } else {
- failed_to_evac = rtsTrue;
- }
- }
-
- /* chain a new block onto the to-space for the destination step if
- * necessary.
- */
- if (stp->scavd_hp + size >= stp->scavd_hpLim) {
- gc_alloc_scavd_block(stp);
- }
-
- to = stp->scavd_hp;
- from = (StgPtr)src;
- stp->scavd_hp = to + size;
- for (i = 0; i < size; i++) { // unroll for small i
- to[i] = from[i];
- }
- upd_evacuee((StgClosure *)from,(StgClosure *)to);
-
-#ifdef PROFILING
- // We store the size of the just evacuated object in the LDV word so that
- // the profiler can guess the position of the next object later.
- SET_EVACUAEE_FOR_LDV(from, size_org);
-#endif
- return (StgClosure *)to;
-}
-
-/* Special version of copy() for when we only want to copy the info
- * pointer of an object, but reserve some padding after it. This is
- * used to optimise evacuation of BLACKHOLEs.
- */
-
-
-static StgClosure *
-copyPart(StgClosure *src, nat size_to_reserve, nat size_to_copy, step *stp)
-{
- P_ dest, to, from;
-#ifdef PROFILING
- // @LDV profiling
- nat size_to_copy_org = size_to_copy;
-#endif
-
- TICK_GC_WORDS_COPIED(size_to_copy);
- if (stp->gen_no < evac_gen) {
- if (eager_promotion) {
- stp = &generations[evac_gen].steps[0];
- } else {
- failed_to_evac = rtsTrue;
- }
- }
-
- if (stp->hp + size_to_reserve >= stp->hpLim) {
- gc_alloc_block(stp);
- }
-
- for(to = stp->hp, from = (P_)src; size_to_copy>0; --size_to_copy) {
- *to++ = *from++;
- }
-
- dest = stp->hp;
- stp->hp += size_to_reserve;
- upd_evacuee(src,(StgClosure *)dest);
-#ifdef PROFILING
- // We store the size of the just evacuated object in the LDV word so that
- // the profiler can guess the position of the next object later.
- // size_to_copy_org is wrong because the closure already occupies size_to_reserve
- // words.
- SET_EVACUAEE_FOR_LDV(src, size_to_reserve);
- // fill the slop
- if (size_to_reserve - size_to_copy_org > 0)
- LDV_FILL_SLOP(stp->hp - 1, (int)(size_to_reserve - size_to_copy_org));
-#endif
- return (StgClosure *)dest;
-}
-
-
-/* -----------------------------------------------------------------------------
- Evacuate a large object
-
- This just consists of removing the object from the (doubly-linked)
- 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
-evacuate_large(StgPtr p)
-{
- bdescr *bd = Bdescr(p);
- step *stp;
-
- // object must be at the beginning of the block (or be a ByteArray)
- ASSERT(get_itbl((StgClosure *)p)->type == ARR_WORDS ||
- (((W_)p & BLOCK_MASK) == 0));
-
- // already evacuated?
- if (bd->flags & BF_EVACUATED) {
- /* Don't forget to set the failed_to_evac flag if we didn't get
- * the desired destination (see comments in evacuate()).
- */
- if (bd->gen_no < evac_gen) {
- failed_to_evac = rtsTrue;
- TICK_GC_FAILED_PROMOTION();
- }
- return;
- }
-
- stp = bd->step;
- // remove from large_object list
- if (bd->u.back) {
- bd->u.back->link = bd->link;
- } else { // first object in the list
- stp->large_objects = bd->link;
- }
- if (bd->link) {
- bd->link->u.back = bd->u.back;
- }
-
- /* link it on to the evacuated large object list of the destination step
- */
- stp = bd->step->to;
- if (stp->gen_no < evac_gen) {
- if (eager_promotion) {
- stp = &generations[evac_gen].steps[0];
- } else {
- failed_to_evac = rtsTrue;
- }
- }
-
- bd->step = stp;
- bd->gen_no = stp->gen_no;
- bd->link = stp->new_large_objects;
- stp->new_large_objects = bd;
- bd->flags |= BF_EVACUATED;
-}
-
-/* -----------------------------------------------------------------------------
- Evacuate
-
- This is called (eventually) for every live object in the system.
-
- The caller to evacuate specifies a desired generation in the
- evac_gen global variable. The following conditions apply to
- evacuating an object which resides in generation M when we're
- collecting up to generation N
-
- if M >= evac_gen
- if M > N do nothing
- else evac to step->to
-
- if M < evac_gen evac to evac_gen, step 0
-
- if the object is already evacuated, then we check which generation
- it now resides in.
-
- if M >= evac_gen do nothing
- if M < evac_gen set failed_to_evac flag to indicate that we
- didn't manage to evacuate this object into evac_gen.
-
-
- OPTIMISATION NOTES:
-
- 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.
- -------------------------------------------------------------------------- */
-
-REGPARM1 static StgClosure *
-evacuate(StgClosure *q)
-{
-#if defined(PAR)
- StgClosure *to;
-#endif
- bdescr *bd = NULL;
- step *stp;
- const StgInfoTable *info;
-
-loop:
- ASSERT(LOOKS_LIKE_CLOSURE_PTR(q));
-
- if (!HEAP_ALLOCED(q)) {
-
- if (!major_gc) return q;
-
- info = get_itbl(q);
- switch (info->type) {
-
- case THUNK_STATIC:
- if (info->srt_bitmap != 0 &&
- *THUNK_STATIC_LINK((StgClosure *)q) == NULL) {
- *THUNK_STATIC_LINK((StgClosure *)q) = static_objects;
- static_objects = (StgClosure *)q;
- }
- return q;
-
- case FUN_STATIC:
- if (info->srt_bitmap != 0 &&
- *FUN_STATIC_LINK((StgClosure *)q) == NULL) {
- *FUN_STATIC_LINK((StgClosure *)q) = static_objects;
- static_objects = (StgClosure *)q;
- }
- return q;
-
- case IND_STATIC:
- /* If q->saved_info != NULL, then it's a revertible CAF - it'll be
- * on the CAF list, so don't do anything with it here (we'll
- * scavenge it later).
- */
- if (((StgIndStatic *)q)->saved_info == NULL
- && *IND_STATIC_LINK((StgClosure *)q) == NULL) {
- *IND_STATIC_LINK((StgClosure *)q) = static_objects;
- static_objects = (StgClosure *)q;
- }
- return q;
-
- case CONSTR_STATIC:
- if (*STATIC_LINK(info,(StgClosure *)q) == NULL) {
- *STATIC_LINK(info,(StgClosure *)q) = static_objects;
- static_objects = (StgClosure *)q;
- }
- return q;
-
- case CONSTR_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));
- }
- }
-
- 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;
- }
-
- 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) {
-
- case MUT_VAR_CLEAN:
- case MUT_VAR_DIRTY:
- case MVAR:
- return copy(q,sizeW_fromITBL(info),stp);
-
- case CONSTR_0_1:
- {
- StgWord w = (StgWord)q->payload[0];
- if (q->header.info == Czh_con_info &&
- // unsigned, so always true: (StgChar)w >= MIN_CHARLIKE &&
- (StgChar)w <= MAX_CHARLIKE) {
- return (StgClosure *)CHARLIKE_CLOSURE((StgChar)w);
- }
- if (q->header.info == Izh_con_info &&
- (StgInt)w >= MIN_INTLIKE && (StgInt)w <= MAX_INTLIKE) {
- return (StgClosure *)INTLIKE_CLOSURE((StgInt)w);
- }
- // else
- return copy_noscav(q,sizeofW(StgHeader)+1,stp);
- }
-
- case FUN_0_1:
- case FUN_1_0:
- case CONSTR_1_0:
- return copy(q,sizeofW(StgHeader)+1,stp);
-
- case THUNK_1_0:
- case THUNK_0_1:
- return copy(q,sizeofW(StgThunk)+1,stp);
-
- case THUNK_1_1:
- case THUNK_2_0:
- case THUNK_0_2:
-#ifdef NO_PROMOTE_THUNKS
- if (bd->gen_no == 0 &&
- bd->step->no != 0 &&
- bd->step->no == generations[bd->gen_no].n_steps-1) {
- stp = bd->step;
- }
-#endif
- return copy(q,sizeofW(StgThunk)+2,stp);
-
- case FUN_1_1:
- case FUN_2_0:
- case CONSTR_1_1:
- case CONSTR_2_0:
- case FUN_0_2:
- return copy(q,sizeofW(StgHeader)+2,stp);
-
- 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 STABLE_NAME:
- 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 THUNK_SELECTOR:
- {
- StgClosure *p;
- const StgInfoTable *info_ptr;
-
- if (thunk_selector_depth > MAX_THUNK_SELECTOR_DEPTH) {
- return copy(q,THUNK_SELECTOR_sizeW(),stp);
- }
-
- // stashed away for LDV profiling, see below
- info_ptr = q->header.info;
-
- p = eval_thunk_selector(info->layout.selector_offset,
- (StgSelector *)q);
-
- if (p == NULL) {
- return copy(q,THUNK_SELECTOR_sizeW(),stp);
- } else {
- StgClosure *val;
- // q is still BLACKHOLE'd.
- thunk_selector_depth++;
- val = evacuate(p);
- thunk_selector_depth--;
-
-#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
-
- // Update the THUNK_SELECTOR with an indirection to the
- // EVACUATED closure now at p. Why do this rather than
- // upd_evacuee(q,p)? Because we have an invariant that an
- // EVACUATED closure always points to an object in the
- // same or an older generation (required by the short-cut
- // test in the EVACUATED case, below).
- SET_INFO(q, &stg_IND_info);
- ((StgInd *)q)->indirectee = p;
-
- // For the purposes of LDV profiling, we have created an
- // indirection.
- LDV_RECORD_CREATE(q);
-
- return val;
- }
- }
-
- case IND:
- case IND_OLDGEN:
- // follow chains of indirections, don't evacuate them
- q = ((StgInd*)q)->indirectee;
- goto loop;
-
- case RET_BCO:
- case RET_SMALL:
- case RET_VEC_SMALL:
- case RET_BIG:
- case RET_VEC_BIG:
- case RET_DYN:
- case UPDATE_FRAME:
- case STOP_FRAME:
- case CATCH_FRAME:
- case CATCH_STM_FRAME:
- case CATCH_RETRY_FRAME:
- case ATOMICALLY_FRAME:
- // shouldn't see these
- barf("evacuate: stack frame at %p\n", q);
-
- case PAP:
- return copy(q,pap_sizeW((StgPAP*)q),stp);
-
- case AP:
- return copy(q,ap_sizeW((StgAP*)q),stp);
-
- case AP_STACK:
- return copy(q,ap_stack_sizeW((StgAP_STACK*)q),stp);
-
- case EVACUATED:
- /* Already evacuated, just return the forwarding address.
- * HOWEVER: if the requested destination generation (evac_gen) is
- * older than the actual generation (because the object was
- * already evacuated to a younger generation) then we have to
- * set the failed_to_evac flag to indicate that we couldn't
- * manage to promote the object to the desired generation.
- */
- /*
- * Optimisation: the check is fairly expensive, but we can often
- * shortcut it if either the required generation is 0, or the
- * current object (the EVACUATED) is in a high enough generation.
- * We know that an EVACUATED always points to an object in the
- * same or an older generation. stp is the lowest step that the
- * current object would be evacuated to, so we only do the full
- * check if stp is too low.
- */
- if (evac_gen > 0 && stp->gen_no < evac_gen) { // optimisation
- StgClosure *p = ((StgEvacuated*)q)->evacuee;
- if (HEAP_ALLOCED(p) && Bdescr((P_)p)->gen_no < evac_gen) {
- failed_to_evac = rtsTrue;
- TICK_GC_FAILED_PROMOTION();
- }
- }
- return ((StgEvacuated*)q)->evacuee;
-
- case ARR_WORDS:
- // just copy the block
- return copy_noscav(q,arr_words_sizeW((StgArrWords *)q),stp);
-
- case MUT_ARR_PTRS_CLEAN:
- case MUT_ARR_PTRS_DIRTY:
- case MUT_ARR_PTRS_FROZEN:
- case MUT_ARR_PTRS_FROZEN0:
- // just copy the block
- return copy(q,mut_arr_ptrs_sizeW((StgMutArrPtrs *)q),stp);
-
- case TSO:
- {
- StgTSO *tso = (StgTSO *)q;
-
- /* Deal with redirected TSOs (a TSO that's had its stack enlarged).
- */
- if (tso->what_next == ThreadRelocated) {
- q = (StgClosure *)tso->link;
- goto loop;
- }
-
- /* To evacuate a small TSO, we need to relocate the update frame
- * list it contains.
- */
- {
- StgTSO *new_tso;
- StgPtr p, q;
-
- new_tso = (StgTSO *)copyPart((StgClosure *)tso,
- tso_sizeW(tso),
- sizeofW(StgTSO), stp);
- move_TSO(tso, new_tso);
- for (p = tso->sp, q = new_tso->sp;
- p < tso->stack+tso->stack_size;) {
- *q++ = *p++;
- }
-
- return (StgClosure *)new_tso;
- }
- }
-
-#if defined(PAR)
- 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);
- debugTrace(DEBUG_gc, "evacuate: RBH %p (%s) to %p (%s)",
- q, info_type(q), to, info_type(to));
- return to;
- }
-
- case BLOCKED_FETCH:
- ASSERT(sizeofW(StgBlockedFetch) >= MIN_PAYLOD_SIZE);
- to = copy(q,sizeofW(StgBlockedFetch),stp);
- debugTrace(DEBUG_gc, "evacuate: %p (%s) to %p (%s)",
- q, info_type(q), to, info_type(to));
- return to;
-
-# ifdef DIST
- case REMOTE_REF:
-# endif
- case FETCH_ME:
- ASSERT(sizeofW(StgBlockedFetch) >= MIN_PAYLOAD_SIZE);
- to = copy(q,sizeofW(StgFetchMe),stp);
- debugTrace(DEBUG_gc, "evacuate: %p (%s) to %p (%s)",
- q, info_type(q), to, info_type(to)));
- return to;
-
- case FETCH_ME_BQ:
- ASSERT(sizeofW(StgBlockedFetch) >= MIN_PAYLOAD_SIZE);
- to = copy(q,sizeofW(StgFetchMeBlockingQueue),stp);
- debugTrace(DEBUG_gc, "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_WATCH_QUEUE:
- return copy(q,sizeofW(StgTVarWatchQueue),stp);
-
- case TVAR:
- return copy(q,sizeofW(StgTVar),stp);
-
- case TREC_CHUNK:
- return copy(q,sizeofW(StgTRecChunk),stp);
-
- case ATOMIC_INVARIANT:
- return copy(q,sizeofW(StgAtomicInvariant),stp);
-
- case INVARIANT_CHECK_QUEUE:
- return copy(q,sizeofW(StgInvariantCheckQueue),stp);
-
- default:
- barf("evacuate: strange closure type %d", (int)(info->type));
- }
-
- barf("evacuate");
-}
-
-/* -----------------------------------------------------------------------------
- Evaluate a THUNK_SELECTOR if possible.
-
- 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.
-
- 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.
-
- ***
- ToDo: the treatment of THUNK_SELECTORS could be improved in the
- following way (from a suggestion by Ian Lynagh):
-
- We can have a chain like this:
-
- sel_0 --> (a,b)
- |
- |-----> sel_0 --> (a,b)
- |
- |-----> sel_0 --> ...
-
- and the depth limit means we don't go all the way to the end of the
- chain, which results in a space leak. This affects the recursive
- call to evacuate() in the THUNK_SELECTOR case in evacuate(): *not*
- the recursive call to eval_thunk_selector() in
- eval_thunk_selector().
-
- We could eliminate the depth bound in this case, in the following
- way:
-
- - traverse the chain once to discover the *value* of the
- THUNK_SELECTOR. Mark all THUNK_SELECTORS that we
- visit on the way as having been visited already (somehow).
-
- - in a second pass, traverse the chain again updating all
- THUNK_SEELCTORS that we find on the way with indirections to
- the value.
-
- - if we encounter a "marked" THUNK_SELECTOR in a normal
- evacuate(), we konw it can't be updated so just evac it.
-
- Program that illustrates the problem:
-
- foo [] = ([], [])
- foo (x:xs) = let (ys, zs) = foo xs
- in if x >= 0 then (x:ys, zs) else (ys, x:zs)
-
- main = bar [1..(100000000::Int)]
- bar xs = (\(ys, zs) -> print ys >> print zs) (foo xs)
-
- -------------------------------------------------------------------------- */
-
-static inline rtsBool
-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 StgClosure *
-eval_thunk_selector( nat field, StgSelector * p )
-{
- StgInfoTable *info;
- const StgInfoTable *info_ptr;
- StgClosure *selectee;
-
- selectee = p->selectee;
-
- // 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;
- }
-
- // 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)
-{
- 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
-#endif
- ) {
- tso->block_info.closure = evacuate(tso->block_info.closure);
- }
- 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);
-}
-
-/* -----------------------------------------------------------------------------
- Scavenge a given step until there are no more objects in this step
- to scavenge.
-
- evac_gen is set by the caller to be either zero (for a step in a
- generation < N) or G where G is the generation of the step being
- scavenged.
-
- We sometimes temporarily change evac_gen back to zero if we're
- scavenging a mutable object where early promotion isn't such a good
- idea.
- -------------------------------------------------------------------------- */
-
-static void
-scavenge(step *stp)
-{
- StgPtr p, q;
- StgInfoTable *info;
- bdescr *bd;
- nat saved_evac_gen = evac_gen;
-
- p = stp->scan;
- bd = stp->scan_bd;
-
- failed_to_evac = rtsFalse;
-
- /* scavenge phase - standard breadth-first scavenging of the
- * evacuated objects
- */
-
- while (bd != stp->hp_bd || p < stp->hp) {
-
- // If we're at the end of this block, move on to the next block
- if (bd != stp->hp_bd && p == bd->free) {
- bd = bd->link;
- p = bd->start;
- continue;
- }
-
- ASSERT(LOOKS_LIKE_CLOSURE_PTR(p));
- info = get_itbl((StgClosure *)p);
-
- ASSERT(thunk_selector_depth == 0);
-
- q = p;
- switch (info->type) {
-
- 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.
- p += sizeofW(StgMVar);
- 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]);
- 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]);
- p += sizeofW(StgHeader) + 2;
- break;
-
- case THUNK_1_0:
- scavenge_thunk_srt(info);
- ((StgThunk *)p)->payload[0] = evacuate(((StgThunk *)p)->payload[0]);
- p += sizeofW(StgThunk) + 1;
- break;
-
- case FUN_1_0:
- 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_thunk_srt(info);
- p += sizeofW(StgThunk) + 1;
- break;
-
- case FUN_0_1:
- 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_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_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:
- {
- 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 STABLE_NAME:
- {
- StgPtr end;
-
- end = (P_)((StgClosure *)p)->payload + info->layout.payload.ptrs;
- for (p = (P_)((StgClosure *)p)->payload; p < end; 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 profiling
- // No need to call LDV_recordDead_FILL_SLOP_DYNAMIC() because an
- // IND_OLDGEN_PERM closure is larger than an IND_PERM closure.
- LDV_recordDead((StgClosure *)p, sizeofW(StgInd));
-#endif
- //
- // Todo: maybe use SET_HDR() and remove LDV_RECORD_CREATE()?
- //
- SET_INFO(((StgClosure *)p), &stg_IND_OLDGEN_PERM_info);
-
- // We pretend that p has just been created.
- LDV_RECORD_CREATE((StgClosure *)p);
- }
- // fall through
- case IND_OLDGEN_PERM:
- ((StgInd *)p)->indirectee = evacuate(((StgInd *)p)->indirectee);
- p += sizeofW(StgInd);
- break;
-
- case MUT_VAR_CLEAN:
- case MUT_VAR_DIRTY: {
- 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;
- }
- p += sizeofW(StgMutVar);
- break;
- }
-
- case CAF_BLACKHOLE:
- case SE_CAF_BLACKHOLE:
- case SE_BLACKHOLE:
- case BLACKHOLE:
- p += BLACKHOLE_sizeW();
- break;
-
- case THUNK_SELECTOR:
- {
- StgSelector *s = (StgSelector *)p;
- s->selectee = evacuate(s->selectee);
- p += THUNK_SELECTOR_sizeW();
- break;
- }
-
- // A chunk of stack saved in a heap object
- 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
- p += arr_words_sizeW((StgArrWords *)p);
- break;
-
- case MUT_ARR_PTRS_CLEAN:
- case MUT_ARR_PTRS_DIRTY:
- // follow everything
- {
- StgPtr next;
- rtsBool saved_eager;
-
- // We don't eagerly promote objects pointed to by a mutable
- // array, but if we find the array only points to objects in
- // the same or an older generation, we mark it "clean" and
- // avoid traversing it during minor GCs.
- saved_eager = eager_promotion;
- eager_promotion = rtsFalse;
- next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p);
- for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) {
- *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
- }
- 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++) {
- *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;
- rtsBool saved_eager = eager_promotion;
-
- eager_promotion = rtsFalse;
- scavengeTSO(tso);
- 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:
- {
-#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.
- debugTrace(DEBUG_gc, "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();
- 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);
- debugTrace(DEBUG_gc, "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);
- break;
- }
-
-#ifdef DIST
- case REMOTE_REF:
-#endif
- case FETCH_ME:
- p += sizeofW(StgFetchMe);
- break; // nothing to do in this case
-
- case FETCH_ME_BQ:
- {
- StgFetchMeBlockingQueue *fmbq = (StgFetchMeBlockingQueue *)p;
- (StgClosure *)fmbq->blocking_queue =
- evacuate((StgClosure *)fmbq->blocking_queue);
- debugTrace(DEBUG_gc, "scavenge: %p (%s) exciting, isn't it",
- p, info_type((StgClosure *)p)));
- p += sizeofW(StgFetchMeBlockingQueue);
- break;
- }
-#endif
-
- case TVAR_WATCH_QUEUE:
- {
- StgTVarWatchQueue *wq = ((StgTVarWatchQueue *) p);
- evac_gen = 0;
- wq->closure = (StgClosure*)evacuate((StgClosure*)wq->closure);
- wq->next_queue_entry = (StgTVarWatchQueue *)evacuate((StgClosure*)wq->next_queue_entry);
- wq->prev_queue_entry = (StgTVarWatchQueue *)evacuate((StgClosure*)wq->prev_queue_entry);
- evac_gen = saved_evac_gen;
- failed_to_evac = rtsTrue; // mutable
- p += sizeofW(StgTVarWatchQueue);
- break;
- }
-
- case TVAR:
- {
- StgTVar *tvar = ((StgTVar *) p);
- evac_gen = 0;
- tvar->current_value = evacuate((StgClosure*)tvar->current_value);
- tvar->first_watch_queue_entry = (StgTVarWatchQueue *)evacuate((StgClosure*)tvar->first_watch_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);
- trec->invariants_to_check = (StgInvariantCheckQueue *)evacuate((StgClosure*)trec->invariants_to_check);
- 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;
- }
-
- case ATOMIC_INVARIANT:
- {
- StgAtomicInvariant *invariant = ((StgAtomicInvariant *) p);
- evac_gen = 0;
- invariant->code = (StgClosure *)evacuate(invariant->code);
- invariant->last_execution = (StgTRecHeader *)evacuate((StgClosure*)invariant->last_execution);
- evac_gen = saved_evac_gen;
- failed_to_evac = rtsTrue; // mutable
- p += sizeofW(StgAtomicInvariant);
- break;
- }
-
- case INVARIANT_CHECK_QUEUE:
- {
- StgInvariantCheckQueue *queue = ((StgInvariantCheckQueue *) p);
- evac_gen = 0;
- queue->invariant = (StgAtomicInvariant *)evacuate((StgClosure*)queue->invariant);
- queue->my_execution = (StgTRecHeader *)evacuate((StgClosure*)queue->my_execution);
- queue->next_queue_entry = (StgInvariantCheckQueue *)evacuate((StgClosure*)queue->next_queue_entry);
- evac_gen = saved_evac_gen;
- failed_to_evac = rtsTrue; // mutable
- p += sizeofW(StgInvariantCheckQueue);
- 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;
- if (stp->gen_no > 0) {
- recordMutableGen((StgClosure *)q, stp->gen);
- }
- }
- }
-
- stp->scan_bd = bd;
- stp->scan = p;
-}
-
-/* -----------------------------------------------------------------------------
- Scavenge everything on the mark stack.
-
- This is slightly different from scavenge():
- - we don't walk linearly through the objects, so the scavenger
- doesn't need to advance the pointer on to the next object.
- -------------------------------------------------------------------------- */
-
-static void
-scavenge_mark_stack(void)
-{
- StgPtr p, q;
- StgInfoTable *info;
- nat saved_evac_gen;
-
- evac_gen = oldest_gen->no;
- saved_evac_gen = evac_gen;
-
-linear_scan:
- while (!mark_stack_empty()) {
- p = pop_mark_stack();
-
- ASSERT(LOOKS_LIKE_CLOSURE_PTR(p));
- info = get_itbl((StgClosure *)p);
-
- q = p;
- switch (info->type) {
-
- 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 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_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]);
- break;
-
- 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_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]);
- break;
-
- case FUN_0_1:
- case FUN_0_2:
- scavenge_fun_srt(info);
- break;
-
- case THUNK_0_1:
- case THUNK_0_2:
- 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:
- {
- 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 STABLE_NAME:
- {
- StgPtr end;
-
- end = (P_)((StgClosure *)p)->payload + info->layout.payload.ptrs;
- for (p = (P_)((StgClosure *)p)->payload; p < end; 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
- // no "old" generation.
- break;
-
- case IND_OLDGEN:
- case IND_OLDGEN_PERM:
- ((StgInd *)p)->indirectee =
- evacuate(((StgInd *)p)->indirectee);
- break;
-
- case MUT_VAR_CLEAN:
- case MUT_VAR_DIRTY: {
- 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:
- case BLACKHOLE:
- case ARR_WORDS:
- break;
-
- case THUNK_SELECTOR:
- {
- StgSelector *s = (StgSelector *)p;
- s->selectee = evacuate(s->selectee);
- break;
- }
-
- // A chunk of stack saved in a heap object
- case AP_STACK:
- {
- StgAP_STACK *ap = (StgAP_STACK *)p;
-
- 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_CLEAN:
- case MUT_ARR_PTRS_DIRTY:
- // follow everything
- {
- StgPtr next;
- rtsBool saved_eager;
-
- // We don't eagerly promote objects pointed to by a mutable
- // array, but if we find the array only points to objects in
- // the same or an older generation, we mark it "clean" and
- // avoid traversing it during minor GCs.
- saved_eager = eager_promotion;
- eager_promotion = rtsFalse;
- next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p);
- for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) {
- *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
- }
- 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, q = p;
-
- next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p);
- for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) {
- *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
- }
-
- // If we're going to put this object on the mutable list, then
- // set its info ptr to MUT_ARR_PTRS_FROZEN0 to indicate that.
- if (failed_to_evac) {
- ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_FROZEN0_info;
- } else {
- ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_FROZEN_info;
- }
- break;
- }
-
- case TSO:
- {
- StgTSO *tso = (StgTSO *)p;
- rtsBool saved_eager = eager_promotion;
-
- eager_promotion = rtsFalse;
- scavengeTSO(tso);
- 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:
- {
-#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;
- bh->blocking_queue =
- (StgTSO *)evacuate((StgClosure *)bh->blocking_queue);
- failed_to_evac = rtsTrue; // mutable anyhow.
- debugTrace(DEBUG_gc, "scavenge: RBH %p (%s) (new blocking_queue link=%p)",
- p, info_type(p), (StgClosure *)rbh->blocking_queue));
- 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);
- debugTrace(DEBUG_gc, "scavenge: %p (%s); node is now %p; exciting, isn't it",
- bf, info_type((StgClosure *)bf),
- bf->node, info_type(bf->node)));
- break;
- }
-
-#ifdef DIST
- case REMOTE_REF:
-#endif
- case FETCH_ME:
- break; // nothing to do in this case
-
- case FETCH_ME_BQ:
- {
- StgFetchMeBlockingQueue *fmbq = (StgFetchMeBlockingQueue *)p;
- (StgClosure *)fmbq->blocking_queue =
- evacuate((StgClosure *)fmbq->blocking_queue);
- debugTrace(DEBUG_gc, "scavenge: %p (%s) exciting, isn't it",
- p, info_type((StgClosure *)p)));
- break;
- }
-#endif /* PAR */
-
- case TVAR_WATCH_QUEUE:
- {
- StgTVarWatchQueue *wq = ((StgTVarWatchQueue *) p);
- evac_gen = 0;
- wq->closure = (StgClosure*)evacuate((StgClosure*)wq->closure);
- wq->next_queue_entry = (StgTVarWatchQueue *)evacuate((StgClosure*)wq->next_queue_entry);
- wq->prev_queue_entry = (StgTVarWatchQueue *)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_watch_queue_entry = (StgTVarWatchQueue *)evacuate((StgClosure*)tvar->first_watch_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);
- trec->invariants_to_check = (StgInvariantCheckQueue *)evacuate((StgClosure*)trec->invariants_to_check);
- evac_gen = saved_evac_gen;
- failed_to_evac = rtsTrue; // mutable
- break;
- }
-
- case ATOMIC_INVARIANT:
- {
- StgAtomicInvariant *invariant = ((StgAtomicInvariant *) p);
- evac_gen = 0;
- invariant->code = (StgClosure *)evacuate(invariant->code);
- invariant->last_execution = (StgTRecHeader *)evacuate((StgClosure*)invariant->last_execution);
- evac_gen = saved_evac_gen;
- failed_to_evac = rtsTrue; // mutable
- break;
- }
-
- case INVARIANT_CHECK_QUEUE:
- {
- StgInvariantCheckQueue *queue = ((StgInvariantCheckQueue *) p);
- evac_gen = 0;
- queue->invariant = (StgAtomicInvariant *)evacuate((StgClosure*)queue->invariant);
- queue->my_execution = (StgTRecHeader *)evacuate((StgClosure*)queue->my_execution);
- queue->next_queue_entry = (StgInvariantCheckQueue *)evacuate((StgClosure*)queue->next_queue_entry);
- evac_gen = saved_evac_gen;
- failed_to_evac = rtsTrue; // mutable
- break;
- }
-
- default:
- barf("scavenge_mark_stack: unimplemented/strange closure type %d @ %p",
- info->type, p);
- }
-
- if (failed_to_evac) {
- failed_to_evac = rtsFalse;
- if (evac_gen > 0) {
- recordMutableGen((StgClosure *)q, &generations[evac_gen]);
- }
- }
-
- // mark the next bit to indicate "scavenged"
- mark(q+1, Bdescr(q));
-
- } // while (!mark_stack_empty())
-
- // start a new linear scan if the mark stack overflowed at some point
- if (mark_stack_overflowed && oldgen_scan_bd == NULL) {
- debugTrace(DEBUG_gc, "scavenge_mark_stack: starting linear scan");
- mark_stack_overflowed = rtsFalse;
- oldgen_scan_bd = oldest_gen->steps[0].old_blocks;
- oldgen_scan = oldgen_scan_bd->start;
- }
-
- if (oldgen_scan_bd) {
- // push a new thing on the mark stack
- loop:
- // find a closure that is marked but not scavenged, and start
- // from there.
- while (oldgen_scan < oldgen_scan_bd->free
- && !is_marked(oldgen_scan,oldgen_scan_bd)) {
- oldgen_scan++;
- }
-
- if (oldgen_scan < oldgen_scan_bd->free) {
-
- // already scavenged?
- if (is_marked(oldgen_scan+1,oldgen_scan_bd)) {
- 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_PAYLOAD_SIZE;
- goto linear_scan;
- }
-
- oldgen_scan_bd = oldgen_scan_bd->link;
- if (oldgen_scan_bd != NULL) {
- oldgen_scan = oldgen_scan_bd->start;
- goto loop;
- }
- }
-}
-
-/* -----------------------------------------------------------------------------
- Scavenge one object.
-
- This is used for objects that are temporarily marked as mutable
- because they contain old-to-new generation pointers. Only certain
- objects can have this property.
- -------------------------------------------------------------------------- */
-
-static rtsBool
-scavenge_one(StgPtr p)
-{
- const StgInfoTable *info;
- nat saved_evac_gen = evac_gen;
- rtsBool no_luck;
-
- ASSERT(LOOKS_LIKE_CLOSURE_PTR(p));
- info = get_itbl((StgClosure *)p);
-
- switch (info->type) {
-
- 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_1_1:
- case CONSTR_0_2:
- case CONSTR_2_0:
- case WEAK:
- case IND_PERM:
- {
- StgPtr q, end;
-
- end = (StgPtr)((StgClosure *)p)->payload + info->layout.payload.ptrs;
- for (q = (StgPtr)((StgClosure *)p)->payload; q < end; 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:
- case BLACKHOLE:
- break;
-
- case THUNK_SELECTOR:
- {
- StgSelector *s = (StgSelector *)p;
- s->selectee = evacuate(s->selectee);
- 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_CLEAN:
- case MUT_ARR_PTRS_DIRTY:
- {
- StgPtr next, q;
- rtsBool saved_eager;
-
- // We don't eagerly promote objects pointed to by a mutable
- // array, but if we find the array only points to objects in
- // the same or an older generation, we mark it "clean" and
- // avoid traversing it during minor GCs.
- saved_eager = eager_promotion;
- eager_promotion = rtsFalse;
- q = p;
- next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p);
- for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) {
- *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
- }
- 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, q=p;
-
- next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p);
- for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) {
- *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
- }
-
- // If we're going to put this object on the mutable list, then
- // set its info ptr to MUT_ARR_PTRS_FROZEN0 to indicate that.
- if (failed_to_evac) {
- ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_FROZEN0_info;
- } else {
- ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_FROZEN_info;
- }
- break;
- }
-
- case TSO:
- {
- StgTSO *tso = (StgTSO *)p;
- rtsBool saved_eager = eager_promotion;
-
- eager_promotion = rtsFalse;
- scavengeTSO(tso);
- 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:
- {
-#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.
- debugTrace(DEBUG_gc, "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 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);
- debugTrace(DEBUG_gc,
- "scavenge: %p (%s); node is now %p; exciting, isn't it",
- bf, info_type((StgClosure *)bf),
- bf->node, info_type(bf->node)));
- break;
- }
-
-#ifdef DIST
- case REMOTE_REF:
-#endif
- case FETCH_ME:
- break; // nothing to do in this case
-
- case FETCH_ME_BQ:
- {
- StgFetchMeBlockingQueue *fmbq = (StgFetchMeBlockingQueue *)p;
- (StgClosure *)fmbq->blocking_queue =
- evacuate((StgClosure *)fmbq->blocking_queue);
- debugTrace(DEBUG_gc, "scavenge: %p (%s) exciting, isn't it",
- p, info_type((StgClosure *)p)));
- break;
- }
-#endif
-
- case TVAR_WATCH_QUEUE:
- {
- StgTVarWatchQueue *wq = ((StgTVarWatchQueue *) p);
- evac_gen = 0;
- wq->closure = (StgClosure*)evacuate((StgClosure*)wq->closure);
- wq->next_queue_entry = (StgTVarWatchQueue *)evacuate((StgClosure*)wq->next_queue_entry);
- wq->prev_queue_entry = (StgTVarWatchQueue *)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_watch_queue_entry = (StgTVarWatchQueue *)evacuate((StgClosure*)tvar->first_watch_queue_entry);
- 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);
- trec->invariants_to_check = (StgInvariantCheckQueue *)evacuate((StgClosure*)trec->invariants_to_check);
- 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 ATOMIC_INVARIANT:
- {
- StgAtomicInvariant *invariant = ((StgAtomicInvariant *) p);
- evac_gen = 0;
- invariant->code = (StgClosure *)evacuate(invariant->code);
- invariant->last_execution = (StgTRecHeader *)evacuate((StgClosure*)invariant->last_execution);
- evac_gen = saved_evac_gen;
- failed_to_evac = rtsTrue; // mutable
- break;
- }
-
- case INVARIANT_CHECK_QUEUE:
- {
- StgInvariantCheckQueue *queue = ((StgInvariantCheckQueue *) p);
- evac_gen = 0;
- queue->invariant = (StgAtomicInvariant *)evacuate((StgClosure*)queue->invariant);
- queue->my_execution = (StgTRecHeader *)evacuate((StgClosure*)queue->my_execution);
- queue->next_queue_entry = (StgInvariantCheckQueue *)evacuate((StgClosure*)queue->next_queue_entry);
- evac_gen = saved_evac_gen;
- failed_to_evac = rtsTrue; // mutable
- break;
- }
-
- case IND_OLDGEN:
- case IND_OLDGEN_PERM:
- case IND_STATIC:
- {
- /* 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
- * promoted
- */
- {
- StgPtr start = gen->steps[0].scan;
- bdescr *start_bd = gen->steps[0].scan_bd;
- nat size = 0;
- scavenge(&gen->steps[0]);
- if (start_bd != gen->steps[0].scan_bd) {
- size += (P_)BLOCK_ROUND_UP(start) - start;
- start_bd = start_bd->link;
- while (start_bd != gen->steps[0].scan_bd) {
- size += BLOCK_SIZE_W;
- start_bd = start_bd->link;
- }
- size += gen->steps[0].scan -
- (P_)BLOCK_ROUND_DOWN(gen->steps[0].scan);
- } else {
- size = gen->steps[0].scan - start;
- }
- debugBelch("evac IND_OLDGEN: %ld bytes", size * sizeof(W_));
- }
-#endif
- break;
-
- default:
- barf("scavenge_one: strange object %d", (int)(info->type));
- }
-
- 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)
-{
- bdescr *bd;
- StgPtr p, q;
-
- 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
-
- // Check whether this object is "clean", that is it
- // definitely doesn't point into a young generation.
- // Clean objects don't need to be scavenged. Some clean
- // objects (MUT_VAR_CLEAN) are not kept on the mutable
- // list at all; others, such as MUT_ARR_PTRS_CLEAN and
- // TSO, are always on the mutable list.
- //
- switch (get_itbl((StgClosure *)p)->type) {
- case MUT_ARR_PTRS_CLEAN:
- recordMutableGen((StgClosure *)p,gen);
- continue;
- case TSO: {
- StgTSO *tso = (StgTSO *)p;
- if ((tso->flags & TSO_DIRTY) == 0) {
- // A clean TSO: we don't have to traverse its
- // stack. However, we *do* follow the link field:
- // we don't want to have to mark a TSO dirty just
- // because we put it on a different queue.
- if (tso->why_blocked != BlockedOnBlackHole) {
- tso->link = (StgTSO *)evacuate((StgClosure *)tso->link);
- }
- recordMutableGen((StgClosure *)p,gen);
- continue;
- }
- }
- default:
- ;
- }
-
- if (scavenge_one(p)) {
- // didn't manage to promote everything, so put the
- // object back on the list.
- recordMutableGen((StgClosure *)p,gen);
- }
- }
- }
-
- // free the old mut_list
- freeChain(gen->saved_mut_list);
- gen->saved_mut_list = NULL;
-}
-
-
-static void
-scavenge_static(void)
-{
- StgClosure* p = static_objects;
- const StgInfoTable *info;
-
- /* Always evacuate straight to the oldest generation for static
- * objects */
- evac_gen = oldest_gen->no;
-
- /* keep going until we've scavenged all the objects on the linked
- list... */
- while (p != END_OF_STATIC_LIST) {
-
- 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
-
- /* Take this object *off* the static_objects list,
- * and put it on the scavenged_static_objects list.
- */
- static_objects = *STATIC_LINK(info,p);
- *STATIC_LINK(info,p) = scavenged_static_objects;
- scavenged_static_objects = p;
-
- switch (info -> type) {
-
- case IND_STATIC:
- {
- StgInd *ind = (StgInd *)p;
- ind->indirectee = evacuate(ind->indirectee);
-
- /* might fail to evacuate it, in which case we have to pop it
- * back on the mutable list 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;
- recordMutableGen((StgClosure *)p,oldest_gen);
- }
- break;
- }
-
- case THUNK_STATIC:
- scavenge_thunk_srt(info);
- break;
-
- case FUN_STATIC:
- scavenge_fun_srt(info);
- break;
-
- case CONSTR_STATIC:
- {
- StgPtr q, next;
-
- next = (P_)p->payload + info->layout.payload.ptrs;
- // evacuate the pointers
- for (q = (P_)p->payload; q < next; q++) {
- *q = (StgWord)(StgPtr)evacuate((StgClosure *)*q);
- }
- break;
- }
-
- default:
- barf("scavenge_static: strange closure %d", (int)(info->type));
- }
-
- ASSERT(failed_to_evac == rtsFalse);
-
- /* get the next static object from the list. Remember, there might
- * be more stuff on this list now that we've done some evacuating!
- * (static_objects is a global)
- */
- p = static_objects;
- }
-}
-
-/* -----------------------------------------------------------------------------
- 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
- AP_STACK_UPDs, since these are just sections of copied stack.
- -------------------------------------------------------------------------- */
-
-
-static void
-scavenge_stack(StgPtr p, StgPtr stack_end)
-{
- const StgRetInfoTable* info;
- StgWord bitmap;
- nat size;
-
- /*
- * Each time around this loop, we are looking at a chunk of stack
- * that starts with an activation record.
- */
-
- while (p < stack_end) {
- info = get_ret_itbl((StgClosure *)p);
-
- switch (info->i.type) {
-
- case UPDATE_FRAME:
- // In SMP, we can get update frames that point to indirections
- // when two threads evaluate the same thunk. We do attempt to
- // discover this situation in threadPaused(), but it's
- // possible that the following sequence occurs:
- //
- // A B
- // enter T
- // enter T
- // blackhole T
- // update T
- // GC
- //
- // Now T is an indirection, and the update frame is already
- // marked on A's stack, so we won't traverse it again in
- // threadPaused(). We could traverse the whole stack again
- // before GC, but that seems like overkill.
- //
- // Scavenging this update frame as normal would be disastrous;
- // the updatee would end up pointing to the value. So we turn
- // the indirection into an IND_PERM, so that evacuate will
- // copy the indirection into the old generation instead of
- // discarding it.
- if (get_itbl(((StgUpdateFrame *)p)->updatee)->type == IND) {
- ((StgUpdateFrame *)p)->updatee->header.info =
- (StgInfoTable *)&stg_IND_PERM_info;
- }
- ((StgUpdateFrame *)p)->updatee
- = evacuate(((StgUpdateFrame *)p)->updatee);
- p += sizeofW(StgUpdateFrame);
- continue;
-
- // 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 RET_SMALL:
- case RET_VEC_SMALL:
- 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++;
- p = scavenge_small_bitmap(p, size, bitmap);
-
- follow_srt:
- 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:
- {
- nat size;
-
- 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;
- }
-
- // 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++;
- }
- continue;
- }
-
- 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->i.type));
- }
- }
-}
-
-/*-----------------------------------------------------------------------------
- scavenge the large object list.
-
- evac_gen set by caller; similar games played with evac_gen as with
- scavenge() - see comment at the top of scavenge(). Most large
- objects are (repeatedly) mutable, so most of the time evac_gen will
- be zero.
- --------------------------------------------------------------------------- */
-
-static void
-scavenge_large(step *stp)
-{
- bdescr *bd;
- StgPtr p;
-
- bd = stp->new_large_objects;
-
- for (; bd != NULL; bd = stp->new_large_objects) {
-
- /* take this object *off* the large objects list and put it on
- * the scavenged large objects list. This is so that we can
- * treat new_large_objects as a stack and push new objects on
- * the front when evacuating.
- */
- stp->new_large_objects = bd->link;
- dbl_link_onto(bd, &stp->scavenged_large_objects);
-
- // update the block count in this step.
- stp->n_scavenged_large_blocks += bd->blocks;
-
- p = bd->start;
- if (scavenge_one(p)) {
- if (stp->gen_no > 0) {
- recordMutableGen((StgClosure *)p, stp->gen);
- }
- }
- }
-}
-
-/* -----------------------------------------------------------------------------
- Initialising the static object & mutable lists
- -------------------------------------------------------------------------- */
-
-static void
-zero_static_object_list(StgClosure* first_static)
-{
- StgClosure* p;
- StgClosure* link;
- const StgInfoTable *info;
-
- 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;
- }
-}
-
-/* -----------------------------------------------------------------------------
- Reverting CAFs
- -------------------------------------------------------------------------- */
-
-void
-revertCAFs( void )
-{
- StgIndStatic *c;
-
- for (c = (StgIndStatic *)revertible_caf_list; c != NULL;
- c = (StgIndStatic *)c->static_link)
- {
- SET_INFO(c, c->saved_info);
- c->saved_info = NULL;
- // could, but not necessary: c->static_link = NULL;
- }
- revertible_caf_list = NULL;
-}
-
-void
-markCAFs( evac_fn evac )
-{
- StgIndStatic *c;
-
- for (c = (StgIndStatic *)caf_list; c != NULL;
- c = (StgIndStatic *)c->static_link)
- {
- evac(&c->indirectee);
- }
- for (c = (StgIndStatic *)revertible_caf_list; c != NULL;
- c = (StgIndStatic *)c->static_link)
- {
- evac(&c->indirectee);
- }
-}
-
-/* -----------------------------------------------------------------------------
- Sanity code for CAF garbage collection.
-
- With DEBUG turned on, we manage a CAF list in addition to the SRT
- mechanism. After GC, we run down the CAF list and blackhole any
- CAFs which have been garbage collected. This means we get an error
- whenever the program tries to enter a garbage collected CAF.
-
- Any garbage collected CAFs are taken off the CAF list at the same
- time.
- -------------------------------------------------------------------------- */
-
-#if 0 && defined(DEBUG)
-
-static void
-gcCAFs(void)
-{
- StgClosure* p;
- StgClosure** pp;
- const StgInfoTable *info;
- nat i;
-
- i = 0;
- p = caf_list;
- pp = &caf_list;
-
- while (p != NULL) {
-
- info = get_itbl(p);
-
- ASSERT(info->type == IND_STATIC);
-
- if (STATIC_LINK(info,p) == NULL) {
- debugTrace(DEBUG_gccafs, "CAF gc'd at 0x%04lx", (long)p);
- // black hole it
- SET_INFO(p,&stg_BLACKHOLE_info);
- p = STATIC_LINK2(info,p);
- *pp = p;
- }
- else {
- pp = &STATIC_LINK2(info,p);
- p = *pp;
- i++;
- }
-
- }
-
- debugTrace(DEBUG_gccafs, "%d CAFs live", i);
-}
-#endif
-
-
-/* -----------------------------------------------------------------------------
- * Stack squeezing
- *
- * Code largely pinched from old RTS, then hacked to bits. We also do
- * lazy black holing here.
- *
- * -------------------------------------------------------------------------- */
-
-struct stack_gap { StgWord gap_size; struct stack_gap *next_gap; };
-
-static void
-stackSqueeze(StgTSO *tso, StgPtr bottom)
-{
- 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));
-
- while (frame < bottom) {
-
- info = get_ret_itbl((StgClosure *)frame);
- switch (info->i.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);
- }
-
- // 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;
-
- // 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;
-
- frame += stack_frame_sizeW((StgClosure *)frame);
- continue;
- }
- }
-
- if (current_gap_size != 0) {
- gap = (struct stack_gap *) (frame - sizeofW(StgUpdateFrame));
- }
-
- // Now we have a stack with gaps in it, and we have to walk down
- // shoving the stack up to fill in the gaps. A diagram might
- // help:
- //
- // +| ********* |
- // | ********* | <- 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;
-
- next_gap_start = (void *)((unsigned char*)gap + sizeof(StgUpdateFrame));
- sp = next_gap_start;
-
- 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;
- }
-}
-
-/* -----------------------------------------------------------------------------
- * 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(Capability *cap, StgTSO *tso)
-{
- StgClosure *frame;
- StgRetInfoTable *info;
- StgClosure *bh;
- StgPtr stack_end;
- nat words_to_squeeze = 0;
- nat weight = 0;
- nat weight_pending = 0;
- rtsBool prev_was_update_frame;
-
- // Check to see whether we have threads waiting to raise
- // exceptions, and we're not blocking exceptions, or are blocked
- // interruptibly. This is important; if a thread is running with
- // TSO_BLOCKEX and becomes blocked interruptibly, this is the only
- // place we ensure that the blocked_exceptions get a chance.
- maybePerformBlockedException (cap, tso);
- if (tso->what_next == ThreadKilled) { return; }
-
- stack_end = &tso->stack[tso->stack_size];
-
- frame = (StgClosure *)tso->sp;
-
- while (1) {
- // If we've already marked this frame, then stop here.
- if (frame->header.info == (StgInfoTable *)&stg_marked_upd_frame_info) {
- goto end;
- }
-
- info = get_ret_itbl(frame);
-
- switch (info->i.type) {
-
- case UPDATE_FRAME:
-
- SET_INFO(frame, (StgInfoTable *)&stg_marked_upd_frame_info);
-
- bh = ((StgUpdateFrame *)frame)->updatee;
-
- if (closure_IND(bh) || bh->header.info == &stg_BLACKHOLE_info) {
- debugTrace(DEBUG_squeeze,
- "suspending duplicate work: %ld words of stack",
- (long)((StgPtr)frame - tso->sp));
-
- // If this closure is already an indirection, then
- // suspend the computation up to this point:
- suspendComputation(cap,tso,(StgPtr)frame);
-
- // Now drop the update frame, and arrange to return
- // the value to the frame underneath:
- tso->sp = (StgPtr)frame + sizeofW(StgUpdateFrame) - 2;
- tso->sp[1] = (StgWord)bh;
- tso->sp[0] = (W_)&stg_enter_info;
-
- // And continue with threadPaused; there might be
- // yet more computation to suspend.
- threadPaused(cap,tso);
- return;
- }
-
- if (bh->header.info != &stg_CAF_BLACKHOLE_info) {
-#if (!defined(LAZY_BLACKHOLING)) && defined(DEBUG)
- debugBelch("Unexpected lazy BHing required at 0x%04lx\n",(long)bh);
-#endif
- // zero out the slop so that the sanity checker can tell
- // where the next closure is.
- DEBUG_FILL_SLOP(bh);
-#ifdef PROFILING
- // @LDV profiling
- // We pretend that bh is now dead.
- LDV_recordDead_FILL_SLOP_DYNAMIC((StgClosure *)bh);
-#endif
- SET_INFO(bh,&stg_BLACKHOLE_info);
-
- // We pretend that bh has just been created.
- LDV_RECORD_CREATE(bh);
- }
-
- frame = (StgClosure *) ((StgUpdateFrame *)frame + 1);
- if (prev_was_update_frame) {
- words_to_squeeze += sizeofW(StgUpdateFrame);
- weight += weight_pending;
- weight_pending = 0;
- }
- prev_was_update_frame = rtsTrue;
- break;
-
- case STOP_FRAME:
- goto end;
-
- // normal stack frames; do nothing except advance the pointer
- default:
- {
- nat frame_size = stack_frame_sizeW(frame);
- weight_pending += frame_size;
- frame = (StgClosure *)((StgPtr)frame + frame_size);
- prev_was_update_frame = rtsFalse;
- }
- }
- }
-
-end:
- debugTrace(DEBUG_squeeze,
- "words_to_squeeze: %d, weight: %d, squeeze: %s",
- 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);
- }
-}
-
-/* -----------------------------------------------------------------------------
- * Debugging
- * -------------------------------------------------------------------------- */
-
-#if DEBUG
-void
-printMutableList(generation *gen)
-{
- bdescr *bd;
- StgPtr p;
-
- debugBelch("mutable list %p: ", gen->mut_list);
-
- 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 */
projects / ghc-hetmet.git / blobdiff