--- /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 "RetainerProfile.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 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
+
+#if defined(DEBUG) && defined(GRAN)
+ IF_DEBUG(gc, debugBelch("@@ Starting garbage collection at %ld (%lx)\n",
+ Now, Now));
+#endif
+
+#if defined(RTS_USER_SIGNALS)
+ // block signals
+ blockUserSignals();
+#endif
+
+ // tell the STM to discard any cached closures its hoping to re-use
+ stmPreGCHook();
+
+ // tell the stats department that we've started a GC
+ stat_startGC();
+
+#ifdef DEBUG
+ // check for memory leaks if DEBUG is on
+ memInventory();
+#endif
+
+#ifdef DEBUG
+ mutlist_MUTVARS = 0;
+ mutlist_MUTARRS = 0;
+ mutlist_OTHERS = 0;
+#endif
+
+ // Init stats and print par specific (timing) info
+ PAR_TICKY_PAR_START();
+
+ // 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;
+
+ IF_DEBUG(gc, debugBelch("bitmap_size: %d, bitmap: %p",
+ bitmap_size, bitmap););
+
+ // don't forget to fill it with zeros!
+ memset(bitmap, 0, bitmap_size);
+
+ // For each block in this step, point to its bitmap from the
+ // 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);
+
+ /* -------------------------------------------------------------------------
+ * 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 (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;
+
+ IF_DEBUG(gc, debugBelch("mut_list_size: %ld (%d vars, %d arrays, %d others)\n", mut_list_size * sizeof(W_), mutlist_MUTVARS, mutlist_MUTARRS, mutlist_OTHERS));
+ }
+
+ for (s = 0; s < generations[g].n_steps; s++) {
+ bdescr *next;
+ stp = &generations[g].steps[s];
+
+ if (!(g == 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);
+ IF_DEBUG(gc, debugBelch("@@ Near maximum heap size of 0x%x blocks, blocks = %d, adjusted to %ld", RtsFlags.GcFlags.maxHeapSize, blocks, adjusted_blocks));
+ pc_free = adjusted_blocks * 100 / RtsFlags.GcFlags.maxHeapSize;
+ if (pc_free < RtsFlags.GcFlags.pcFreeHeap) /* might even be < 0 */ {
+ heapOverflow();
+ }
+ blocks = 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;
+ IF_DEBUG(weak, debugBelch("Weak pointer still alive at %p -> %p",
+ w, w->key));
+ continue;
+ }
+ else {
+ last_w = &(w->link);
+ next_w = w->link;
+ continue;
+ }
+
+ 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:
+ ;
+ }
+
+ // Threads blocked on black holes: if the black hole
+ // is alive, then the thread is alive too.
+ if (tmp == NULL && t->why_blocked == BlockedOnBlackHole) {
+ if (isAlive(t->block_info.closure)) {
+ t = (StgTSO *)evacuate((StgClosure *)t);
+ tmp = t;
+ flag = rtsTrue;
+ }
+ }
+
+ if (tmp == NULL) {
+ // not alive (yet): leave this thread on the
+ // old_all_threads list.
+ 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;
+ }
+
+}
+
+/* -----------------------------------------------------------------------------
+ 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_INTLIKE:
+ case CONSTR_CHARLIKE:
+ case CONSTR_NOCAF_STATIC:
+ /* no need to put these on the static linked list, they don't need
+ * to be scavenged.
+ */
+ return q;
+
+ default:
+ barf("evacuate(static): strange closure type %d", (int)(info->type));
+ }
+ }
+
+ 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);
+ IF_DEBUG(gc,
+ debugBelch("@@ evacuate: RBH %p (%s) to %p (%s)",
+ q, info_type(q), to, info_type(to)));
+ return to;
+ }
+
+ case BLOCKED_FETCH:
+ ASSERT(sizeofW(StgBlockedFetch) >= MIN_PAYLOD_SIZE);
+ to = copy(q,sizeofW(StgBlockedFetch),stp);
+ IF_DEBUG(gc,
+ debugBelch("@@ 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);
+ IF_DEBUG(gc,
+ debugBelch("@@ evacuate: %p (%s) to %p (%s)",
+ q, info_type(q), to, info_type(to)));
+ return to;
+
+ case FETCH_ME_BQ:
+ ASSERT(sizeofW(StgBlockedFetch) >= MIN_PAYLOAD_SIZE);
+ to = copy(q,sizeofW(StgFetchMeBlockingQueue),stp);
+ IF_DEBUG(gc,
+ debugBelch("@@ evacuate: %p (%s) to %p (%s)",
+ q, info_type(q), to, info_type(to)));
+ return to;
+#endif
+
+ case TREC_HEADER:
+ return copy(q,sizeofW(StgTRecHeader),stp);
+
+ case TVAR_WAIT_QUEUE:
+ return copy(q,sizeofW(StgTVarWaitQueue),stp);
+
+ case TVAR:
+ return copy(q,sizeofW(StgTVar),stp);
+
+ case TREC_CHUNK:
+ return copy(q,sizeofW(StgTRecChunk),stp);
+
+ default:
+ barf("evacuate: strange closure type %d", (int)(info->type));
+ }
+
+ 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);
+ }
+ if ( tso->blocked_exceptions != NULL ) {
+ tso->blocked_exceptions =
+ (StgTSO *)evacuate((StgClosure *)tso->blocked_exceptions);
+ }
+
+ // We don't always chase the link field: TSOs on the blackhole
+ // queue are not automatically alive, so the link field is a
+ // "weak" pointer in that case.
+ if (tso->why_blocked != BlockedOnBlackHole) {
+ tso->link = (StgTSO *)evacuate((StgClosure *)tso->link);
+ }
+
+ // scavange current transaction record
+ tso->trec = (StgTRecHeader *)evacuate((StgClosure *)tso->trec);
+
+ // scavenge this thread's stack
+ scavenge_stack(tso->sp, &(tso->stack[tso->stack_size]));
+}
+
+/* -----------------------------------------------------------------------------
+ Blocks of function args occur on the stack (at the top) and
+ in PAPs.
+ -------------------------------------------------------------------------- */
+
+STATIC_INLINE StgPtr
+scavenge_arg_block (StgFunInfoTable *fun_info, StgClosure **args)
+{
+ StgPtr p;
+ StgWord bitmap;
+ nat size;
+
+ p = (StgPtr)args;
+ switch (fun_info->f.fun_type) {
+ case ARG_GEN:
+ bitmap = BITMAP_BITS(fun_info->f.b.bitmap);
+ size = BITMAP_SIZE(fun_info->f.b.bitmap);
+ goto small_bitmap;
+ case ARG_GEN_BIG:
+ size = GET_FUN_LARGE_BITMAP(fun_info)->size;
+ scavenge_large_bitmap(p, GET_FUN_LARGE_BITMAP(fun_info), size);
+ p += size;
+ break;
+ default:
+ bitmap = BITMAP_BITS(stg_arg_bitmaps[fun_info->f.fun_type]);
+ size = BITMAP_SIZE(stg_arg_bitmaps[fun_info->f.fun_type]);
+ small_bitmap:
+ while (size > 0) {
+ if ((bitmap & 1) == 0) {
+ *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
+ }
+ p++;
+ bitmap = bitmap >> 1;
+ size--;
+ }
+ break;
+ }
+ return p;
+}
+
+STATIC_INLINE StgPtr
+scavenge_PAP_payload (StgClosure *fun, StgClosure **payload, StgWord size)
+{
+ StgPtr p;
+ StgWord bitmap;
+ StgFunInfoTable *fun_info;
+
+ fun_info = get_fun_itbl(fun);
+ ASSERT(fun_info->i.type != PAP);
+ p = (StgPtr)payload;
+
+ switch (fun_info->f.fun_type) {
+ case ARG_GEN:
+ bitmap = BITMAP_BITS(fun_info->f.b.bitmap);
+ goto small_bitmap;
+ case ARG_GEN_BIG:
+ scavenge_large_bitmap(p, GET_FUN_LARGE_BITMAP(fun_info), size);
+ p += size;
+ break;
+ case ARG_BCO:
+ scavenge_large_bitmap((StgPtr)payload, BCO_BITMAP(fun), size);
+ p += size;
+ break;
+ default:
+ bitmap = BITMAP_BITS(stg_arg_bitmaps[fun_info->f.fun_type]);
+ small_bitmap:
+ while (size > 0) {
+ if ((bitmap & 1) == 0) {
+ *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p);
+ }
+ p++;
+ bitmap = bitmap >> 1;
+ size--;
+ }
+ break;
+ }
+ return p;
+}
+
+STATIC_INLINE StgPtr
+scavenge_PAP (StgPAP *pap)
+{
+ pap->fun = evacuate(pap->fun);
+ return scavenge_PAP_payload (pap->fun, pap->payload, pap->n_args);
+}
+
+STATIC_INLINE StgPtr
+scavenge_AP (StgAP *ap)
+{
+ ap->fun = evacuate(ap->fun);
+ return scavenge_PAP_payload (ap->fun, ap->payload, ap->n_args);
+}
+
+/* -----------------------------------------------------------------------------
+ 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.
+ IF_DEBUG(gc,
+ debugBelch("@@ scavenge: RBH %p (%s) (new blocking_queue link=%p)",
+ p, info_type(p), (StgClosure *)rbh->blocking_queue));
+ // ToDo: use size of reverted closure here!
+ p += BLACKHOLE_sizeW();
+ break;
+ }
+
+ case BLOCKED_FETCH:
+ {
+ StgBlockedFetch *bf = (StgBlockedFetch *)p;
+ // follow the pointer to the node which is being demanded
+ (StgClosure *)bf->node =
+ evacuate((StgClosure *)bf->node);
+ // follow the link to the rest of the blocking queue
+ (StgClosure *)bf->link =
+ evacuate((StgClosure *)bf->link);
+ IF_DEBUG(gc,
+ debugBelch("@@ scavenge: %p (%s); node is now %p; exciting, isn't it",
+ bf, info_type((StgClosure *)bf),
+ bf->node, info_type(bf->node)));
+ 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);
+ IF_DEBUG(gc,
+ debugBelch("@@ scavenge: %p (%s) exciting, isn't it",
+ p, info_type((StgClosure *)p)));
+ p += sizeofW(StgFetchMeBlockingQueue);
+ break;
+ }
+#endif
+
+ case TVAR_WAIT_QUEUE:
+ {
+ StgTVarWaitQueue *wq = ((StgTVarWaitQueue *) p);
+ evac_gen = 0;
+ wq->waiting_tso = (StgTSO *)evacuate((StgClosure*)wq->waiting_tso);
+ wq->next_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)wq->next_queue_entry);
+ wq->prev_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)wq->prev_queue_entry);
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ p += sizeofW(StgTVarWaitQueue);
+ break;
+ }
+
+ case TVAR:
+ {
+ StgTVar *tvar = ((StgTVar *) p);
+ evac_gen = 0;
+ tvar->current_value = evacuate((StgClosure*)tvar->current_value);
+ tvar->first_wait_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)tvar->first_wait_queue_entry);
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ p += sizeofW(StgTVar);
+ break;
+ }
+
+ case TREC_HEADER:
+ {
+ StgTRecHeader *trec = ((StgTRecHeader *) p);
+ evac_gen = 0;
+ trec->enclosing_trec = (StgTRecHeader *)evacuate((StgClosure*)trec->enclosing_trec);
+ trec->current_chunk = (StgTRecChunk *)evacuate((StgClosure*)trec->current_chunk);
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ p += sizeofW(StgTRecHeader);
+ break;
+ }
+
+ case TREC_CHUNK:
+ {
+ StgWord i;
+ StgTRecChunk *tc = ((StgTRecChunk *) p);
+ TRecEntry *e = &(tc -> entries[0]);
+ evac_gen = 0;
+ tc->prev_chunk = (StgTRecChunk *)evacuate((StgClosure*)tc->prev_chunk);
+ for (i = 0; i < tc -> next_entry_idx; i ++, e++ ) {
+ e->tvar = (StgTVar *)evacuate((StgClosure*)e->tvar);
+ e->expected_value = evacuate((StgClosure*)e->expected_value);
+ e->new_value = evacuate((StgClosure*)e->new_value);
+ }
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ p += sizeofW(StgTRecChunk);
+ break;
+ }
+
+ default:
+ barf("scavenge: unimplemented/strange closure type %d @ %p",
+ info->type, p);
+ }
+
+ /*
+ * We need to record the current object on the mutable list if
+ * (a) It is actually mutable, or
+ * (b) It contains pointers to a younger generation.
+ * Case (b) arises if we didn't manage to promote everything that
+ * the current object points to into the current generation.
+ */
+ if (failed_to_evac) {
+ failed_to_evac = rtsFalse;
+ 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.
+ IF_DEBUG(gc,
+ debugBelch("@@ 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);
+ IF_DEBUG(gc,
+ debugBelch("@@ scavenge: %p (%s); node is now %p; exciting, isn't it",
+ bf, info_type((StgClosure *)bf),
+ bf->node, info_type(bf->node)));
+ break;
+ }
+
+#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);
+ IF_DEBUG(gc,
+ debugBelch("@@ scavenge: %p (%s) exciting, isn't it",
+ p, info_type((StgClosure *)p)));
+ break;
+ }
+#endif /* PAR */
+
+ case TVAR_WAIT_QUEUE:
+ {
+ StgTVarWaitQueue *wq = ((StgTVarWaitQueue *) p);
+ evac_gen = 0;
+ wq->waiting_tso = (StgTSO *)evacuate((StgClosure*)wq->waiting_tso);
+ wq->next_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)wq->next_queue_entry);
+ wq->prev_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)wq->prev_queue_entry);
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ break;
+ }
+
+ case TVAR:
+ {
+ StgTVar *tvar = ((StgTVar *) p);
+ evac_gen = 0;
+ tvar->current_value = evacuate((StgClosure*)tvar->current_value);
+ tvar->first_wait_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)tvar->first_wait_queue_entry);
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ break;
+ }
+
+ case TREC_CHUNK:
+ {
+ StgWord i;
+ StgTRecChunk *tc = ((StgTRecChunk *) p);
+ TRecEntry *e = &(tc -> entries[0]);
+ evac_gen = 0;
+ tc->prev_chunk = (StgTRecChunk *)evacuate((StgClosure*)tc->prev_chunk);
+ for (i = 0; i < tc -> next_entry_idx; i ++, e++ ) {
+ e->tvar = (StgTVar *)evacuate((StgClosure*)e->tvar);
+ e->expected_value = evacuate((StgClosure*)e->expected_value);
+ e->new_value = evacuate((StgClosure*)e->new_value);
+ }
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ break;
+ }
+
+ case TREC_HEADER:
+ {
+ StgTRecHeader *trec = ((StgTRecHeader *) p);
+ evac_gen = 0;
+ trec->enclosing_trec = (StgTRecHeader *)evacuate((StgClosure*)trec->enclosing_trec);
+ trec->current_chunk = (StgTRecChunk *)evacuate((StgClosure*)trec->current_chunk);
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ break;
+ }
+
+ default:
+ barf("scavenge_mark_stack: unimplemented/strange closure type %d @ %p",
+ 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) {
+ IF_DEBUG(gc, debugBelch("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.
+ IF_DEBUG(gc,
+ debugBelch("@@ scavenge: RBH %p (%s) (new blocking_queue link=%p)",
+ p, info_type(p), (StgClosure *)rbh->blocking_queue));
+ // ToDo: use size of reverted closure here!
+ break;
+ }
+
+ case BLOCKED_FETCH:
+ {
+ StgBlockedFetch *bf = (StgBlockedFetch *)p;
+ // follow the pointer to the node which is being demanded
+ (StgClosure *)bf->node =
+ evacuate((StgClosure *)bf->node);
+ // follow the link to the rest of the blocking queue
+ (StgClosure *)bf->link =
+ evacuate((StgClosure *)bf->link);
+ IF_DEBUG(gc,
+ debugBelch("@@ scavenge: %p (%s); node is now %p; exciting, isn't it",
+ bf, info_type((StgClosure *)bf),
+ bf->node, info_type(bf->node)));
+ break;
+ }
+
+#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);
+ IF_DEBUG(gc,
+ debugBelch("@@ scavenge: %p (%s) exciting, isn't it",
+ p, info_type((StgClosure *)p)));
+ break;
+ }
+#endif
+
+ case TVAR_WAIT_QUEUE:
+ {
+ StgTVarWaitQueue *wq = ((StgTVarWaitQueue *) p);
+ evac_gen = 0;
+ wq->waiting_tso = (StgTSO *)evacuate((StgClosure*)wq->waiting_tso);
+ wq->next_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)wq->next_queue_entry);
+ wq->prev_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)wq->prev_queue_entry);
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ break;
+ }
+
+ case TVAR:
+ {
+ StgTVar *tvar = ((StgTVar *) p);
+ evac_gen = 0;
+ tvar->current_value = evacuate((StgClosure*)tvar->current_value);
+ tvar->first_wait_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)tvar->first_wait_queue_entry);
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ break;
+ }
+
+ case TREC_HEADER:
+ {
+ StgTRecHeader *trec = ((StgTRecHeader *) p);
+ evac_gen = 0;
+ trec->enclosing_trec = (StgTRecHeader *)evacuate((StgClosure*)trec->enclosing_trec);
+ trec->current_chunk = (StgTRecChunk *)evacuate((StgClosure*)trec->current_chunk);
+ evac_gen = saved_evac_gen;
+ failed_to_evac = rtsTrue; // mutable
+ break;
+ }
+
+ 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 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;
+
+ //IF_DEBUG(sanity, debugBelch(" scavenging stack between %p and %p", p, stack_end));
+
+ /*
+ * Each time around this loop, we are looking at a chunk of stack
+ * that starts with 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) {
+ IF_DEBUG(gccafs, debugBelch("CAF gc'd at 0x%04lx", (long)p));
+ // black hole it
+ SET_INFO(p,&stg_BLACKHOLE_info);
+ p = STATIC_LINK2(info,p);
+ *pp = p;
+ }
+ else {
+ pp = &STATIC_LINK2(info,p);
+ p = *pp;
+ i++;
+ }
+
+ }
+
+ // debugBelch("%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;
+
+ stack_end = &tso->stack[tso->stack_size];
+
+ frame = (StgClosure *)tso->sp;
+
+ while (1) {
+ // If we've already marked this frame, then stop here.
+ if (frame->header.info == (StgInfoTable *)&stg_marked_upd_frame_info) {
+ goto end;
+ }
+
+ info = get_ret_itbl(frame);
+
+ switch (info->i.type) {
+
+ case UPDATE_FRAME:
+
+ SET_INFO(frame, (StgInfoTable *)&stg_marked_upd_frame_info);
+
+ bh = ((StgUpdateFrame *)frame)->updatee;
+
+ if (closure_IND(bh) || bh->header.info == &stg_BLACKHOLE_info) {
+ IF_DEBUG(squeeze, debugBelch("suspending duplicate work: %ld words of stack\n", (StgPtr)frame - tso->sp));
+
+ // If this closure is already an indirection, then
+ // suspend the computation up to this point:
+ suspendComputation(cap,tso,(StgPtr)frame);
+
+ // Now drop the update frame, and arrange to return
+ // the value to the frame underneath:
+ tso->sp = (StgPtr)frame + sizeofW(StgUpdateFrame) - 2;
+ tso->sp[1] = (StgWord)bh;
+ tso->sp[0] = (W_)&stg_enter_info;
+
+ // And continue with threadPaused; there might be
+ // yet more computation to suspend.
+ threadPaused(cap,tso);
+ return;
+ }
+
+ if (bh->header.info != &stg_CAF_BLACKHOLE_info) {
+#if (!defined(LAZY_BLACKHOLING)) && defined(DEBUG)
+ debugBelch("Unexpected lazy BHing required at 0x%04lx\n",(long)bh);
+#endif
+ // zero out the slop so that the sanity checker can tell
+ // where the next closure is.
+ DEBUG_FILL_SLOP(bh);
+#ifdef PROFILING
+ // @LDV profiling
+ // We pretend that bh is now dead.
+ LDV_recordDead_FILL_SLOP_DYNAMIC((StgClosure *)bh);
+#endif
+ SET_INFO(bh,&stg_BLACKHOLE_info);
+
+ // We pretend that bh has just been created.
+ LDV_RECORD_CREATE(bh);
+ }
+
+ frame = (StgClosure *) ((StgUpdateFrame *)frame + 1);
+ if (prev_was_update_frame) {
+ words_to_squeeze += sizeofW(StgUpdateFrame);
+ weight += weight_pending;
+ weight_pending = 0;
+ }
+ prev_was_update_frame = rtsTrue;
+ break;
+
+ case STOP_FRAME:
+ goto end;
+
+ // normal stack frames; do nothing except advance the pointer
+ default:
+ {
+ nat frame_size = stack_frame_sizeW(frame);
+ weight_pending += frame_size;
+ frame = (StgClosure *)((StgPtr)frame + frame_size);
+ prev_was_update_frame = rtsFalse;
+ }
+ }
+ }
+
+end:
+ IF_DEBUG(squeeze,
+ debugBelch("words_to_squeeze: %d, weight: %d, squeeze: %s\n",
+ words_to_squeeze, weight,
+ weight < words_to_squeeze ? "YES" : "NO"));
+
+ // Should we squeeze or not? Arbitrary heuristic: we squeeze if
+ // the number of words we have to shift down is less than the
+ // number of stack words we squeeze away by doing so.
+ if (RtsFlags.GcFlags.squeezeUpdFrames == rtsTrue &&
+ weight < words_to_squeeze) {
+ stackSqueeze(tso, (StgPtr)frame);
+ }
+}
+
+/* -----------------------------------------------------------------------------
+ * 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