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Diffstat (limited to 'rts/GC.c')
| -rw-r--r-- | rts/GC.c | 4825 |
1 files changed, 0 insertions, 4825 deletions
diff --git a/rts/GC.c b/rts/GC.c deleted file mode 100644 index 4e8b3c2a26..0000000000 --- a/rts/GC.c +++ /dev/null @@ -1,4825 +0,0 @@ -/* ----------------------------------------------------------------------------- - * - * (c) The GHC Team 1998-2003 - * - * Generational garbage collector - * - * ---------------------------------------------------------------------------*/ - -#include "PosixSource.h" -#include "Rts.h" -#include "RtsFlags.h" -#include "RtsUtils.h" -#include "Apply.h" -#include "OSThreads.h" -#include "Storage.h" -#include "LdvProfile.h" -#include "Updates.h" -#include "Stats.h" -#include "Schedule.h" -#include "Sanity.h" -#include "BlockAlloc.h" -#include "MBlock.h" -#include "ProfHeap.h" -#include "SchedAPI.h" -#include "Weak.h" -#include "Prelude.h" -#include "ParTicky.h" // ToDo: move into Rts.h -#include "GCCompact.h" -#include "RtsSignals.h" -#include "STM.h" -#if defined(GRAN) || defined(PAR) -# include "GranSimRts.h" -# include "ParallelRts.h" -# include "FetchMe.h" -# if defined(DEBUG) -# include "Printer.h" -# include "ParallelDebug.h" -# endif -#endif -#include "HsFFI.h" -#include "Linker.h" -#if defined(RTS_GTK_FRONTPANEL) -#include "FrontPanel.h" -#endif -#include "Trace.h" -#include "RetainerProfile.h" -#include "RaiseAsync.h" - -#include <string.h> - -// Turn off inlining when debugging - it obfuscates things -#ifdef DEBUG -# undef STATIC_INLINE -# define STATIC_INLINE static -#endif - -/* STATIC OBJECT LIST. - * - * During GC: - * We maintain a linked list of static objects that are still live. - * The requirements for this list are: - * - * - we need to scan the list while adding to it, in order to - * scavenge all the static objects (in the same way that - * breadth-first scavenging works for dynamic objects). - * - * - we need to be able to tell whether an object is already on - * the list, to break loops. - * - * Each static object has a "static link field", which we use for - * linking objects on to the list. We use a stack-type list, consing - * objects on the front as they are added (this means that the - * scavenge phase is depth-first, not breadth-first, but that - * shouldn't matter). - * - * A separate list is kept for objects that have been scavenged - * already - this is so that we can zero all the marks afterwards. - * - * An object is on the list if its static link field is non-zero; this - * means that we have to mark the end of the list with '1', not NULL. - * - * Extra notes for generational GC: - * - * Each generation has a static object list associated with it. When - * collecting generations up to N, we treat the static object lists - * from generations > N as roots. - * - * We build up a static object list while collecting generations 0..N, - * which is then appended to the static object list of generation N+1. - */ -static StgClosure* static_objects; // live static objects -StgClosure* scavenged_static_objects; // static objects scavenged so far - -/* N is the oldest generation being collected, where the generations - * are numbered starting at 0. A major GC (indicated by the major_gc - * flag) is when we're collecting all generations. We only attempt to - * deal with static objects and GC CAFs when doing a major GC. - */ -static nat N; -static rtsBool major_gc; - -/* Youngest generation that objects should be evacuated to in - * evacuate(). (Logically an argument to evacuate, but it's static - * a lot of the time so we optimise it into a global variable). - */ -static nat evac_gen; - -/* Whether to do eager promotion or not. - */ -static rtsBool eager_promotion; - -/* Weak pointers - */ -StgWeak *old_weak_ptr_list; // also pending finaliser list - -/* Which stage of processing various kinds of weak pointer are we at? - * (see traverse_weak_ptr_list() below for discussion). - */ -typedef enum { WeakPtrs, WeakThreads, WeakDone } WeakStage; -static WeakStage weak_stage; - -/* List of all threads during GC - */ -static StgTSO *old_all_threads; -StgTSO *resurrected_threads; - -/* Flag indicating failure to evacuate an object to the desired - * generation. - */ -static rtsBool failed_to_evac; - -/* Saved nursery (used for 2-space collector only) - */ -static bdescr *saved_nursery; -static nat saved_n_blocks; - -/* Data used for allocation area sizing. - */ -static lnat new_blocks; // blocks allocated during this GC -static lnat new_scavd_blocks; // ditto, but depth-first blocks -static lnat g0s0_pcnt_kept = 30; // percentage of g0s0 live at last minor GC - -/* Used to avoid long recursion due to selector thunks - */ -static lnat thunk_selector_depth = 0; -#define MAX_THUNK_SELECTOR_DEPTH 8 - -/* Mut-list stats */ -#ifdef DEBUG -static nat - mutlist_MUTVARS, - mutlist_MUTARRS, - mutlist_OTHERS; -#endif - -/* ----------------------------------------------------------------------------- - Static function declarations - -------------------------------------------------------------------------- */ - -static bdescr * gc_alloc_block ( step *stp ); -static void mark_root ( StgClosure **root ); - -// Use a register argument for evacuate, if available. -#if __GNUC__ >= 2 -#define REGPARM1 __attribute__((regparm(1))) -#else -#define REGPARM1 -#endif - -REGPARM1 static StgClosure * evacuate (StgClosure *q); - -static void zero_static_object_list ( StgClosure* first_static ); - -static rtsBool traverse_weak_ptr_list ( void ); -static void mark_weak_ptr_list ( StgWeak **list ); -static rtsBool traverse_blackhole_queue ( void ); - -static StgClosure * eval_thunk_selector ( nat field, StgSelector * p ); - - -static void scavenge ( step * ); -static void scavenge_mark_stack ( void ); -static void scavenge_stack ( StgPtr p, StgPtr stack_end ); -static rtsBool scavenge_one ( StgPtr p ); -static void scavenge_large ( step * ); -static void scavenge_static ( void ); -static void scavenge_mutable_list ( generation *g ); - -static void scavenge_large_bitmap ( StgPtr p, - StgLargeBitmap *large_bitmap, - nat size ); - -#if 0 && defined(DEBUG) -static void gcCAFs ( void ); -#endif - -/* ----------------------------------------------------------------------------- - inline functions etc. for dealing with the mark bitmap & stack. - -------------------------------------------------------------------------- */ - -#define MARK_STACK_BLOCKS 4 - -static bdescr *mark_stack_bdescr; -static StgPtr *mark_stack; -static StgPtr *mark_sp; -static StgPtr *mark_splim; - -// Flag and pointers used for falling back to a linear scan when the -// mark stack overflows. -static rtsBool mark_stack_overflowed; -static bdescr *oldgen_scan_bd; -static StgPtr oldgen_scan; - -STATIC_INLINE rtsBool -mark_stack_empty(void) -{ - return mark_sp == mark_stack; -} - -STATIC_INLINE rtsBool -mark_stack_full(void) -{ - return mark_sp >= mark_splim; -} - -STATIC_INLINE void -reset_mark_stack(void) -{ - mark_sp = mark_stack; -} - -STATIC_INLINE void -push_mark_stack(StgPtr p) -{ - *mark_sp++ = p; -} - -STATIC_INLINE StgPtr -pop_mark_stack(void) -{ - return *--mark_sp; -} - -/* ----------------------------------------------------------------------------- - Allocate a new to-space block in the given step. - -------------------------------------------------------------------------- */ - -static bdescr * -gc_alloc_block(step *stp) -{ - bdescr *bd = allocBlock(); - bd->gen_no = stp->gen_no; - bd->step = stp; - bd->link = NULL; - - // blocks in to-space in generations up to and including N - // get the BF_EVACUATED flag. - if (stp->gen_no <= N) { - bd->flags = BF_EVACUATED; - } else { - bd->flags = 0; - } - - // Start a new to-space block, chain it on after the previous one. - if (stp->hp_bd != NULL) { - stp->hp_bd->free = stp->hp; - stp->hp_bd->link = bd; - } - - stp->hp_bd = bd; - stp->hp = bd->start; - stp->hpLim = stp->hp + BLOCK_SIZE_W; - - stp->n_blocks++; - new_blocks++; - - return bd; -} - -static bdescr * -gc_alloc_scavd_block(step *stp) -{ - bdescr *bd = allocBlock(); - bd->gen_no = stp->gen_no; - bd->step = stp; - - // blocks in to-space in generations up to and including N - // get the BF_EVACUATED flag. - if (stp->gen_no <= N) { - bd->flags = BF_EVACUATED; - } else { - bd->flags = 0; - } - - bd->link = stp->blocks; - stp->blocks = bd; - - if (stp->scavd_hp != NULL) { - Bdescr(stp->scavd_hp)->free = stp->scavd_hp; - } - stp->scavd_hp = bd->start; - stp->scavd_hpLim = stp->scavd_hp + BLOCK_SIZE_W; - - stp->n_blocks++; - new_scavd_blocks++; - - return bd; -} - -/* ----------------------------------------------------------------------------- - GarbageCollect - - Rough outline of the algorithm: for garbage collecting generation N - (and all younger generations): - - - follow all pointers in the root set. the root set includes all - mutable objects in all generations (mutable_list). - - - for each pointer, evacuate the object it points to into either - - + to-space of the step given by step->to, which is the next - highest step in this generation or the first step in the next - generation if this is the last step. - - + to-space of generations[evac_gen]->steps[0], if evac_gen != 0. - When we evacuate an object we attempt to evacuate - everything it points to into the same generation - this is - achieved by setting evac_gen to the desired generation. If - we can't do this, then an entry in the mut list has to - be made for the cross-generation pointer. - - + if the object is already in a generation > N, then leave - it alone. - - - repeatedly scavenge to-space from each step in each generation - being collected until no more objects can be evacuated. - - - free from-space in each step, and set from-space = to-space. - - Locks held: all capabilities are held throughout GarbageCollect(). - - -------------------------------------------------------------------------- */ - -void -GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) -{ - bdescr *bd; - step *stp; - lnat live, allocated, copied = 0, scavd_copied = 0; - lnat oldgen_saved_blocks = 0; - nat g, s, i; - - ACQUIRE_SM_LOCK; - -#ifdef PROFILING - CostCentreStack *prev_CCS; -#endif - - debugTrace(DEBUG_gc, "starting GC"); - -#if defined(RTS_USER_SIGNALS) - // block signals - blockUserSignals(); -#endif - - // tell the STM to discard any cached closures its hoping to re-use - stmPreGCHook(); - - // tell the stats department that we've started a GC - stat_startGC(); - -#ifdef DEBUG - // check for memory leaks if DEBUG is on - memInventory(); -#endif - -#ifdef DEBUG - mutlist_MUTVARS = 0; - mutlist_MUTARRS = 0; - mutlist_OTHERS = 0; -#endif - - // Init stats and print par specific (timing) info - PAR_TICKY_PAR_START(); - - // attribute any costs to CCS_GC -#ifdef PROFILING - prev_CCS = CCCS; - CCCS = CCS_GC; -#endif - - /* Approximate how much we allocated. - * Todo: only when generating stats? - */ - allocated = calcAllocated(); - - /* Figure out which generation to collect - */ - if (force_major_gc) { - N = RtsFlags.GcFlags.generations - 1; - major_gc = rtsTrue; - } else { - N = 0; - for (g = 0; g < RtsFlags.GcFlags.generations; g++) { - if (generations[g].steps[0].n_blocks + - generations[g].steps[0].n_large_blocks - >= generations[g].max_blocks) { - N = g; - } - } - major_gc = (N == RtsFlags.GcFlags.generations-1); - } - -#ifdef RTS_GTK_FRONTPANEL - if (RtsFlags.GcFlags.frontpanel) { - updateFrontPanelBeforeGC(N); - } -#endif - - // check stack sanity *before* GC (ToDo: check all threads) -#if defined(GRAN) - // ToDo!: check sanity IF_DEBUG(sanity, checkTSOsSanity()); -#endif - IF_DEBUG(sanity, checkFreeListSanity()); - - /* Initialise the static object lists - */ - static_objects = END_OF_STATIC_LIST; - scavenged_static_objects = END_OF_STATIC_LIST; - - /* Save the nursery if we're doing a two-space collection. - * g0s0->blocks will be used for to-space, so we need to get the - * nursery out of the way. - */ - if (RtsFlags.GcFlags.generations == 1) { - saved_nursery = g0s0->blocks; - saved_n_blocks = g0s0->n_blocks; - g0s0->blocks = NULL; - g0s0->n_blocks = 0; - } - - /* Keep a count of how many new blocks we allocated during this GC - * (used for resizing the allocation area, later). - */ - new_blocks = 0; - new_scavd_blocks = 0; - - // Initialise to-space in all the generations/steps that we're - // collecting. - // - for (g = 0; g <= N; g++) { - - // throw away the mutable list. Invariant: the mutable list - // always has at least one block; this means we can avoid a check for - // NULL in recordMutable(). - if (g != 0) { - freeChain(generations[g].mut_list); - generations[g].mut_list = allocBlock(); - for (i = 0; i < n_capabilities; i++) { - freeChain(capabilities[i].mut_lists[g]); - capabilities[i].mut_lists[g] = allocBlock(); - } - } - - for (s = 0; s < generations[g].n_steps; s++) { - - // generation 0, step 0 doesn't need to-space - if (g == 0 && s == 0 && RtsFlags.GcFlags.generations > 1) { - continue; - } - - stp = &generations[g].steps[s]; - ASSERT(stp->gen_no == g); - - // start a new to-space for this step. - stp->old_blocks = stp->blocks; - stp->n_old_blocks = stp->n_blocks; - - // allocate the first to-space block; extra blocks will be - // chained on as necessary. - stp->hp_bd = NULL; - bd = gc_alloc_block(stp); - stp->blocks = bd; - stp->n_blocks = 1; - stp->scan = bd->start; - stp->scan_bd = bd; - - // allocate a block for "already scavenged" objects. This goes - // on the front of the stp->blocks list, so it won't be - // traversed by the scavenging sweep. - gc_alloc_scavd_block(stp); - - // initialise the large object queues. - stp->new_large_objects = NULL; - stp->scavenged_large_objects = NULL; - stp->n_scavenged_large_blocks = 0; - - // mark the large objects as not evacuated yet - for (bd = stp->large_objects; bd; bd = bd->link) { - bd->flags &= ~BF_EVACUATED; - } - - // for a compacted step, we need to allocate the bitmap - if (stp->is_compacted) { - nat bitmap_size; // in bytes - bdescr *bitmap_bdescr; - StgWord *bitmap; - - bitmap_size = stp->n_old_blocks * BLOCK_SIZE / (sizeof(W_)*BITS_PER_BYTE); - - if (bitmap_size > 0) { - bitmap_bdescr = allocGroup((lnat)BLOCK_ROUND_UP(bitmap_size) - / BLOCK_SIZE); - stp->bitmap = bitmap_bdescr; - bitmap = bitmap_bdescr->start; - - debugTrace(DEBUG_gc, "bitmap_size: %d, bitmap: %p", - bitmap_size, bitmap); - - // don't forget to fill it with zeros! - memset(bitmap, 0, bitmap_size); - - // For each block in this step, point to its bitmap from the - // block descriptor. - for (bd=stp->old_blocks; bd != NULL; bd = bd->link) { - bd->u.bitmap = bitmap; - bitmap += BLOCK_SIZE_W / (sizeof(W_)*BITS_PER_BYTE); - - // Also at this point we set the BF_COMPACTED flag - // for this block. The invariant is that - // BF_COMPACTED is always unset, except during GC - // when it is set on those blocks which will be - // compacted. - bd->flags |= BF_COMPACTED; - } - } - } - } - } - - /* make sure the older generations have at least one block to - * allocate into (this makes things easier for copy(), see below). - */ - for (g = N+1; g < RtsFlags.GcFlags.generations; g++) { - for (s = 0; s < generations[g].n_steps; s++) { - stp = &generations[g].steps[s]; - if (stp->hp_bd == NULL) { - ASSERT(stp->blocks == NULL); - bd = gc_alloc_block(stp); - stp->blocks = bd; - stp->n_blocks = 1; - } - if (stp->scavd_hp == NULL) { - gc_alloc_scavd_block(stp); - stp->n_blocks++; - } - /* Set the scan pointer for older generations: remember we - * still have to scavenge objects that have been promoted. */ - stp->scan = stp->hp; - stp->scan_bd = stp->hp_bd; - stp->new_large_objects = NULL; - stp->scavenged_large_objects = NULL; - stp->n_scavenged_large_blocks = 0; - } - - /* Move the private mutable lists from each capability onto the - * main mutable list for the generation. - */ - for (i = 0; i < n_capabilities; i++) { - for (bd = capabilities[i].mut_lists[g]; - bd->link != NULL; bd = bd->link) { - /* nothing */ - } - bd->link = generations[g].mut_list; - generations[g].mut_list = capabilities[i].mut_lists[g]; - capabilities[i].mut_lists[g] = allocBlock(); - } - } - - /* Allocate a mark stack if we're doing a major collection. - */ - if (major_gc) { - mark_stack_bdescr = allocGroup(MARK_STACK_BLOCKS); - mark_stack = (StgPtr *)mark_stack_bdescr->start; - mark_sp = mark_stack; - mark_splim = mark_stack + (MARK_STACK_BLOCKS * BLOCK_SIZE_W); - } else { - mark_stack_bdescr = NULL; - } - - eager_promotion = rtsTrue; // for now - - /* ----------------------------------------------------------------------- - * follow all the roots that we know about: - * - mutable lists from each generation > N - * we want to *scavenge* these roots, not evacuate them: they're not - * going to move in this GC. - * Also: do them in reverse generation order. This is because we - * often want to promote objects that are pointed to by older - * generations early, so we don't have to repeatedly copy them. - * Doing the generations in reverse order ensures that we don't end - * up in the situation where we want to evac an object to gen 3 and - * it has already been evaced to gen 2. - */ - { - int st; - for (g = RtsFlags.GcFlags.generations-1; g > N; g--) { - generations[g].saved_mut_list = generations[g].mut_list; - generations[g].mut_list = allocBlock(); - // mut_list always has at least one block. - } - - for (g = RtsFlags.GcFlags.generations-1; g > N; g--) { - IF_PAR_DEBUG(verbose, printMutableList(&generations[g])); - scavenge_mutable_list(&generations[g]); - evac_gen = g; - for (st = generations[g].n_steps-1; st >= 0; st--) { - scavenge(&generations[g].steps[st]); - } - } - } - - /* follow roots from the CAF list (used by GHCi) - */ - evac_gen = 0; - markCAFs(mark_root); - - /* follow all the roots that the application knows about. - */ - evac_gen = 0; - get_roots(mark_root); - -#if defined(PAR) - /* And don't forget to mark the TSO if we got here direct from - * Haskell! */ - /* Not needed in a seq version? - if (CurrentTSO) { - CurrentTSO = (StgTSO *)MarkRoot((StgClosure *)CurrentTSO); - } - */ - - // Mark the entries in the GALA table of the parallel system - markLocalGAs(major_gc); - // Mark all entries on the list of pending fetches - markPendingFetches(major_gc); -#endif - - /* Mark the weak pointer list, and prepare to detect dead weak - * pointers. - */ - mark_weak_ptr_list(&weak_ptr_list); - old_weak_ptr_list = weak_ptr_list; - weak_ptr_list = NULL; - weak_stage = WeakPtrs; - - /* The all_threads list is like the weak_ptr_list. - * See traverse_weak_ptr_list() for the details. - */ - old_all_threads = all_threads; - all_threads = END_TSO_QUEUE; - resurrected_threads = END_TSO_QUEUE; - - /* Mark the stable pointer table. - */ - markStablePtrTable(mark_root); - - /* Mark the root pointer table. - */ - markRootPtrTable(mark_root); - - /* ------------------------------------------------------------------------- - * Repeatedly scavenge all the areas we know about until there's no - * more scavenging to be done. - */ - { - rtsBool flag; - loop: - flag = rtsFalse; - - // scavenge static objects - if (major_gc && static_objects != END_OF_STATIC_LIST) { - IF_DEBUG(sanity, checkStaticObjects(static_objects)); - scavenge_static(); - } - - /* When scavenging the older generations: Objects may have been - * evacuated from generations <= N into older generations, and we - * need to scavenge these objects. We're going to try to ensure that - * any evacuations that occur move the objects into at least the - * same generation as the object being scavenged, otherwise we - * have to create new entries on the mutable list for the older - * generation. - */ - - // scavenge each step in generations 0..maxgen - { - long gen; - int st; - - loop2: - // scavenge objects in compacted generation - if (mark_stack_overflowed || oldgen_scan_bd != NULL || - (mark_stack_bdescr != NULL && !mark_stack_empty())) { - scavenge_mark_stack(); - flag = rtsTrue; - } - - for (gen = RtsFlags.GcFlags.generations; --gen >= 0; ) { - for (st = generations[gen].n_steps; --st >= 0; ) { - if (gen == 0 && st == 0 && RtsFlags.GcFlags.generations > 1) { - continue; - } - stp = &generations[gen].steps[st]; - evac_gen = gen; - if (stp->hp_bd != stp->scan_bd || stp->scan < stp->hp) { - scavenge(stp); - flag = rtsTrue; - goto loop2; - } - if (stp->new_large_objects != NULL) { - scavenge_large(stp); - flag = rtsTrue; - goto loop2; - } - } - } - } - - // if any blackholes are alive, make the threads that wait on - // them alive too. - if (traverse_blackhole_queue()) - flag = rtsTrue; - - if (flag) { goto loop; } - - // must be last... invariant is that everything is fully - // scavenged at this point. - if (traverse_weak_ptr_list()) { // returns rtsTrue if evaced something - goto loop; - } - } - - /* Update the pointers from the task list - these are - * treated as weak pointers because we want to allow a main thread - * to get a BlockedOnDeadMVar exception in the same way as any other - * thread. Note that the threads should all have been retained by - * GC by virtue of being on the all_threads list, we're just - * updating pointers here. - */ - { - Task *task; - StgTSO *tso; - for (task = all_tasks; task != NULL; task = task->all_link) { - if (!task->stopped && task->tso) { - ASSERT(task->tso->bound == task); - tso = (StgTSO *) isAlive((StgClosure *)task->tso); - if (tso == NULL) { - barf("task %p: main thread %d has been GC'd", -#ifdef THREADED_RTS - (void *)task->id, -#else - (void *)task, -#endif - task->tso->id); - } - task->tso = tso; - } - } - } - -#if defined(PAR) - // Reconstruct the Global Address tables used in GUM - rebuildGAtables(major_gc); - IF_DEBUG(sanity, checkLAGAtable(rtsTrue/*check closures, too*/)); -#endif - - // Now see which stable names are still alive. - gcStablePtrTable(); - - // Tidy the end of the to-space chains - for (g = 0; g < RtsFlags.GcFlags.generations; g++) { - for (s = 0; s < generations[g].n_steps; s++) { - stp = &generations[g].steps[s]; - if (!(g == 0 && s == 0 && RtsFlags.GcFlags.generations > 1)) { - ASSERT(Bdescr(stp->hp) == stp->hp_bd); - stp->hp_bd->free = stp->hp; - Bdescr(stp->scavd_hp)->free = stp->scavd_hp; - } - } - } - -#ifdef PROFILING - // We call processHeapClosureForDead() on every closure destroyed during - // the current garbage collection, so we invoke LdvCensusForDead(). - if (RtsFlags.ProfFlags.doHeapProfile == HEAP_BY_LDV - || RtsFlags.ProfFlags.bioSelector != NULL) - LdvCensusForDead(N); -#endif - - // NO MORE EVACUATION AFTER THIS POINT! - // Finally: compaction of the oldest generation. - if (major_gc && oldest_gen->steps[0].is_compacted) { - // save number of blocks for stats - oldgen_saved_blocks = oldest_gen->steps[0].n_old_blocks; - compact(get_roots); - } - - IF_DEBUG(sanity, checkGlobalTSOList(rtsFalse)); - - /* run through all the generations/steps and tidy up - */ - copied = new_blocks * BLOCK_SIZE_W; - scavd_copied = new_scavd_blocks * BLOCK_SIZE_W; - for (g = 0; g < RtsFlags.GcFlags.generations; g++) { - - if (g <= N) { - generations[g].collections++; // for stats - } - - // Count the mutable list as bytes "copied" for the purposes of - // stats. Every mutable list is copied during every GC. - if (g > 0) { - nat mut_list_size = 0; - for (bd = generations[g].mut_list; bd != NULL; bd = bd->link) { - mut_list_size += bd->free - bd->start; - } - copied += mut_list_size; - - debugTrace(DEBUG_gc, - "mut_list_size: %lu (%d vars, %d arrays, %d others)", - (unsigned long)(mut_list_size * sizeof(W_)), - mutlist_MUTVARS, mutlist_MUTARRS, mutlist_OTHERS); - } - - for (s = 0; s < generations[g].n_steps; s++) { - bdescr *next; - stp = &generations[g].steps[s]; - - if (!(g == 0 && s == 0 && RtsFlags.GcFlags.generations > 1)) { - // stats information: how much we copied - if (g <= N) { - copied -= stp->hp_bd->start + BLOCK_SIZE_W - - stp->hp_bd->free; - scavd_copied -= (P_)(BLOCK_ROUND_UP(stp->scavd_hp)) - stp->scavd_hp; - } - } - - // for generations we collected... - if (g <= N) { - - /* free old memory and shift to-space into from-space for all - * the collected steps (except the allocation area). These - * freed blocks will probaby be quickly recycled. - */ - if (!(g == 0 && s == 0)) { - if (stp->is_compacted) { - // for a compacted step, just shift the new to-space - // onto the front of the now-compacted existing blocks. - for (bd = stp->blocks; bd != NULL; bd = bd->link) { - bd->flags &= ~BF_EVACUATED; // now from-space - } - // tack the new blocks on the end of the existing blocks - if (stp->old_blocks != NULL) { - for (bd = stp->old_blocks; bd != NULL; bd = next) { - // NB. this step might not be compacted next - // time, so reset the BF_COMPACTED flags. - // They are set before GC if we're going to - // compact. (search for BF_COMPACTED above). - bd->flags &= ~BF_COMPACTED; - next = bd->link; - if (next == NULL) { - bd->link = stp->blocks; - } - } - stp->blocks = stp->old_blocks; - } - // add the new blocks to the block tally - stp->n_blocks += stp->n_old_blocks; - ASSERT(countBlocks(stp->blocks) == stp->n_blocks); - } else { - freeChain(stp->old_blocks); - for (bd = stp->blocks; bd != NULL; bd = bd->link) { - bd->flags &= ~BF_EVACUATED; // now from-space - } - } - stp->old_blocks = NULL; - stp->n_old_blocks = 0; - } - - /* LARGE OBJECTS. The current live large objects are chained on - * scavenged_large, having been moved during garbage - * collection from large_objects. Any objects left on - * large_objects list are therefore dead, so we free them here. - */ - for (bd = stp->large_objects; bd != NULL; bd = next) { - next = bd->link; - freeGroup(bd); - bd = next; - } - - // update the count of blocks used by large objects - for (bd = stp->scavenged_large_objects; bd != NULL; bd = bd->link) { - bd->flags &= ~BF_EVACUATED; - } - stp->large_objects = stp->scavenged_large_objects; - stp->n_large_blocks = stp->n_scavenged_large_blocks; - - } else { - // for older generations... - - /* For older generations, we need to append the - * scavenged_large_object list (i.e. large objects that have been - * promoted during this GC) to the large_object list for that step. - */ - for (bd = stp->scavenged_large_objects; bd; bd = next) { - next = bd->link; - bd->flags &= ~BF_EVACUATED; - dbl_link_onto(bd, &stp->large_objects); - } - - // add the new blocks we promoted during this GC - stp->n_large_blocks += stp->n_scavenged_large_blocks; - } - } - } - - /* Reset the sizes of the older generations when we do a major - * collection. - * - * CURRENT STRATEGY: make all generations except zero the same size. - * We have to stay within the maximum heap size, and leave a certain - * percentage of the maximum heap size available to allocate into. - */ - if (major_gc && RtsFlags.GcFlags.generations > 1) { - nat live, size, min_alloc; - nat max = RtsFlags.GcFlags.maxHeapSize; - nat gens = RtsFlags.GcFlags.generations; - - // live in the oldest generations - live = oldest_gen->steps[0].n_blocks + - oldest_gen->steps[0].n_large_blocks; - - // default max size for all generations except zero - size = stg_max(live * RtsFlags.GcFlags.oldGenFactor, - RtsFlags.GcFlags.minOldGenSize); - - // minimum size for generation zero - min_alloc = stg_max((RtsFlags.GcFlags.pcFreeHeap * max) / 200, - RtsFlags.GcFlags.minAllocAreaSize); - - // Auto-enable compaction when the residency reaches a - // certain percentage of the maximum heap size (default: 30%). - if (RtsFlags.GcFlags.generations > 1 && - (RtsFlags.GcFlags.compact || - (max > 0 && - oldest_gen->steps[0].n_blocks > - (RtsFlags.GcFlags.compactThreshold * max) / 100))) { - oldest_gen->steps[0].is_compacted = 1; -// debugBelch("compaction: on\n", live); - } else { - oldest_gen->steps[0].is_compacted = 0; -// debugBelch("compaction: off\n", live); - } - - // if we're going to go over the maximum heap size, reduce the - // size of the generations accordingly. The calculation is - // different if compaction is turned on, because we don't need - // to double the space required to collect the old generation. - if (max != 0) { - - // this test is necessary to ensure that the calculations - // below don't have any negative results - we're working - // with unsigned values here. - if (max < min_alloc) { - heapOverflow(); - } - - if (oldest_gen->steps[0].is_compacted) { - if ( (size + (size - 1) * (gens - 2) * 2) + min_alloc > max ) { - size = (max - min_alloc) / ((gens - 1) * 2 - 1); - } - } else { - if ( (size * (gens - 1) * 2) + min_alloc > max ) { - size = (max - min_alloc) / ((gens - 1) * 2); - } - } - - if (size < live) { - heapOverflow(); - } - } - -#if 0 - debugBelch("live: %d, min_alloc: %d, size : %d, max = %d\n", live, - min_alloc, size, max); -#endif - - for (g = 0; g < gens; g++) { - generations[g].max_blocks = size; - } - } - - // Guess the amount of live data for stats. - live = calcLive(); - - /* Free the small objects allocated via allocate(), since this will - * all have been copied into G0S1 now. - */ - if (small_alloc_list != NULL) { - freeChain(small_alloc_list); - } - small_alloc_list = NULL; - alloc_blocks = 0; - alloc_Hp = NULL; - alloc_HpLim = NULL; - alloc_blocks_lim = RtsFlags.GcFlags.minAllocAreaSize; - - // Start a new pinned_object_block - pinned_object_block = NULL; - - /* Free the mark stack. - */ - if (mark_stack_bdescr != NULL) { - freeGroup(mark_stack_bdescr); - } - - /* Free any bitmaps. - */ - for (g = 0; g <= N; g++) { - for (s = 0; s < generations[g].n_steps; s++) { - stp = &generations[g].steps[s]; - if (stp->bitmap != NULL) { - freeGroup(stp->bitmap); - stp->bitmap = NULL; - } - } - } - - /* Two-space collector: - * Free the old to-space, and estimate the amount of live data. - */ - if (RtsFlags.GcFlags.generations == 1) { - nat blocks; - - if (g0s0->old_blocks != NULL) { - freeChain(g0s0->old_blocks); - } - for (bd = g0s0->blocks; bd != NULL; bd = bd->link) { - bd->flags = 0; // now from-space - } - g0s0->old_blocks = g0s0->blocks; - g0s0->n_old_blocks = g0s0->n_blocks; - g0s0->blocks = saved_nursery; - g0s0->n_blocks = saved_n_blocks; - - /* For a two-space collector, we need to resize the nursery. */ - - /* set up a new nursery. Allocate a nursery size based on a - * function of the amount of live data (by default a factor of 2) - * Use the blocks from the old nursery if possible, freeing up any - * left over blocks. - * - * If we get near the maximum heap size, then adjust our nursery - * size accordingly. If the nursery is the same size as the live - * data (L), then we need 3L bytes. We can reduce the size of the - * nursery to bring the required memory down near 2L bytes. - * - * A normal 2-space collector would need 4L bytes to give the same - * performance we get from 3L bytes, reducing to the same - * performance at 2L bytes. - */ - blocks = g0s0->n_old_blocks; - - if ( RtsFlags.GcFlags.maxHeapSize != 0 && - blocks * RtsFlags.GcFlags.oldGenFactor * 2 > - RtsFlags.GcFlags.maxHeapSize ) { - long adjusted_blocks; // signed on purpose - int pc_free; - - adjusted_blocks = (RtsFlags.GcFlags.maxHeapSize - 2 * blocks); - - debugTrace(DEBUG_gc, "near maximum heap size of 0x%x blocks, blocks = %d, adjusted to %ld", - RtsFlags.GcFlags.maxHeapSize, blocks, adjusted_blocks); - - pc_free = adjusted_blocks * 100 / RtsFlags.GcFlags.maxHeapSize; - if (pc_free < RtsFlags.GcFlags.pcFreeHeap) /* might even be < 0 */ { - heapOverflow(); - } - blocks = adjusted_blocks; - - } else { - blocks *= RtsFlags.GcFlags.oldGenFactor; - if (blocks < RtsFlags.GcFlags.minAllocAreaSize) { - blocks = RtsFlags.GcFlags.minAllocAreaSize; - } - } - resizeNurseries(blocks); - - } else { - /* Generational collector: - * If the user has given us a suggested heap size, adjust our - * allocation area to make best use of the memory available. - */ - - if (RtsFlags.GcFlags.heapSizeSuggestion) { - long blocks; - nat needed = calcNeeded(); // approx blocks needed at next GC - - /* Guess how much will be live in generation 0 step 0 next time. - * A good approximation is obtained by finding the - * percentage of g0s0 that was live at the last minor GC. - */ - if (N == 0) { - g0s0_pcnt_kept = (new_blocks * 100) / countNurseryBlocks(); - } - - /* Estimate a size for the allocation area based on the - * information available. We might end up going slightly under - * or over the suggested heap size, but we should be pretty - * close on average. - * - * Formula: suggested - needed - * ---------------------------- - * 1 + g0s0_pcnt_kept/100 - * - * where 'needed' is the amount of memory needed at the next - * collection for collecting all steps except g0s0. - */ - blocks = - (((long)RtsFlags.GcFlags.heapSizeSuggestion - (long)needed) * 100) / - (100 + (long)g0s0_pcnt_kept); - - if (blocks < (long)RtsFlags.GcFlags.minAllocAreaSize) { - blocks = RtsFlags.GcFlags.minAllocAreaSize; - } - - resizeNurseries((nat)blocks); - - } else { - // we might have added extra large blocks to the nursery, so - // resize back to minAllocAreaSize again. - resizeNurseriesFixed(RtsFlags.GcFlags.minAllocAreaSize); - } - } - - // mark the garbage collected CAFs as dead -#if 0 && defined(DEBUG) // doesn't work at the moment - if (major_gc) { gcCAFs(); } -#endif - -#ifdef PROFILING - // resetStaticObjectForRetainerProfiling() must be called before - // zeroing below. - resetStaticObjectForRetainerProfiling(); -#endif - - // zero the scavenged static object list - if (major_gc) { - zero_static_object_list(scavenged_static_objects); - } - - // Reset the nursery - resetNurseries(); - - // start any pending finalizers - RELEASE_SM_LOCK; - scheduleFinalizers(last_free_capability, old_weak_ptr_list); - ACQUIRE_SM_LOCK; - - // send exceptions to any threads which were about to die - RELEASE_SM_LOCK; - resurrectThreads(resurrected_threads); - ACQUIRE_SM_LOCK; - - // Update the stable pointer hash table. - updateStablePtrTable(major_gc); - - // check sanity after GC - IF_DEBUG(sanity, checkSanity()); - - // extra GC trace info - IF_DEBUG(gc, statDescribeGens()); - -#ifdef DEBUG - // symbol-table based profiling - /* heapCensus(to_blocks); */ /* ToDo */ -#endif - - // restore enclosing cost centre -#ifdef PROFILING - CCCS = prev_CCS; -#endif - -#ifdef DEBUG - // check for memory leaks if DEBUG is on - memInventory(); -#endif - -#ifdef RTS_GTK_FRONTPANEL - if (RtsFlags.GcFlags.frontpanel) { - updateFrontPanelAfterGC( N, live ); - } -#endif - - // ok, GC over: tell the stats department what happened. - stat_endGC(allocated, live, copied, scavd_copied, N); - -#if defined(RTS_USER_SIGNALS) - // unblock signals again - unblockUserSignals(); -#endif - - RELEASE_SM_LOCK; - - //PAR_TICKY_TP(); -} - - -/* ----------------------------------------------------------------------------- - Weak Pointers - - traverse_weak_ptr_list is called possibly many times during garbage - collection. It returns a flag indicating whether it did any work - (i.e. called evacuate on any live pointers). - - Invariant: traverse_weak_ptr_list is called when the heap is in an - idempotent state. That means that there are no pending - evacuate/scavenge operations. This invariant helps the weak - pointer code decide which weak pointers are dead - if there are no - new live weak pointers, then all the currently unreachable ones are - dead. - - For generational GC: we just don't try to finalize weak pointers in - older generations than the one we're collecting. This could - probably be optimised by keeping per-generation lists of weak - pointers, but for a few weak pointers this scheme will work. - - There are three distinct stages to processing weak pointers: - - - weak_stage == WeakPtrs - - We process all the weak pointers whos keys are alive (evacuate - their values and finalizers), and repeat until we can find no new - live keys. If no live keys are found in this pass, then we - evacuate the finalizers of all the dead weak pointers in order to - run them. - - - weak_stage == WeakThreads - - Now, we discover which *threads* are still alive. Pointers to - threads from the all_threads and main thread lists are the - weakest of all: a pointers from the finalizer of a dead weak - pointer can keep a thread alive. Any threads found to be unreachable - are evacuated and placed on the resurrected_threads list so we - can send them a signal later. - - - weak_stage == WeakDone - - No more evacuation is done. - - -------------------------------------------------------------------------- */ - -static rtsBool -traverse_weak_ptr_list(void) -{ - StgWeak *w, **last_w, *next_w; - StgClosure *new; - rtsBool flag = rtsFalse; - - switch (weak_stage) { - - case WeakDone: - return rtsFalse; - - case WeakPtrs: - /* doesn't matter where we evacuate values/finalizers to, since - * these pointers are treated as roots (iff the keys are alive). - */ - evac_gen = 0; - - last_w = &old_weak_ptr_list; - for (w = old_weak_ptr_list; w != NULL; w = next_w) { - - /* There might be a DEAD_WEAK on the list if finalizeWeak# was - * called on a live weak pointer object. Just remove it. - */ - if (w->header.info == &stg_DEAD_WEAK_info) { - next_w = ((StgDeadWeak *)w)->link; - *last_w = next_w; - continue; - } - - switch (get_itbl(w)->type) { - - case EVACUATED: - next_w = (StgWeak *)((StgEvacuated *)w)->evacuee; - *last_w = next_w; - continue; - - case WEAK: - /* Now, check whether the key is reachable. - */ - new = isAlive(w->key); - if (new != NULL) { - w->key = new; - // evacuate the value and finalizer - w->value = evacuate(w->value); - w->finalizer = evacuate(w->finalizer); - // remove this weak ptr from the old_weak_ptr list - *last_w = w->link; - // and put it on the new weak ptr list - next_w = w->link; - w->link = weak_ptr_list; - weak_ptr_list = w; - flag = rtsTrue; - - debugTrace(DEBUG_weak, - "weak pointer still alive at %p -> %p", - w, w->key); - continue; - } - else { - last_w = &(w->link); - next_w = w->link; - continue; - } - - default: - barf("traverse_weak_ptr_list: not WEAK"); - } - } - - /* If we didn't make any changes, then we can go round and kill all - * the dead weak pointers. The old_weak_ptr list is used as a list - * of pending finalizers later on. - */ - if (flag == rtsFalse) { - for (w = old_weak_ptr_list; w; w = w->link) { - w->finalizer = evacuate(w->finalizer); - } - - // Next, move to the WeakThreads stage after fully - // scavenging the finalizers we've just evacuated. - weak_stage = WeakThreads; - } - - return rtsTrue; - - case WeakThreads: - /* Now deal with the all_threads list, which behaves somewhat like - * the weak ptr list. If we discover any threads that are about to - * become garbage, we wake them up and administer an exception. - */ - { - StgTSO *t, *tmp, *next, **prev; - - prev = &old_all_threads; - for (t = old_all_threads; t != END_TSO_QUEUE; t = next) { - - tmp = (StgTSO *)isAlive((StgClosure *)t); - - if (tmp != NULL) { - t = tmp; - } - - ASSERT(get_itbl(t)->type == TSO); - switch (t->what_next) { - case ThreadRelocated: - next = t->link; - *prev = next; - continue; - case ThreadKilled: - case ThreadComplete: - // finshed or died. The thread might still be alive, but we - // don't keep it on the all_threads list. Don't forget to - // stub out its global_link field. - next = t->global_link; - t->global_link = END_TSO_QUEUE; - *prev = next; - continue; - default: - ; - } - - if (tmp == NULL) { - // not alive (yet): leave this thread on the - // old_all_threads list. - prev = &(t->global_link); - next = t->global_link; - } - else { - // alive: move this thread onto the all_threads list. - next = t->global_link; - t->global_link = all_threads; - all_threads = t; - *prev = next; - } - } - } - - /* If we evacuated any threads, we need to go back to the scavenger. - */ - if (flag) return rtsTrue; - - /* And resurrect any threads which were about to become garbage. - */ - { - StgTSO *t, *tmp, *next; - for (t = old_all_threads; t != END_TSO_QUEUE; t = next) { - next = t->global_link; - tmp = (StgTSO *)evacuate((StgClosure *)t); - tmp->global_link = resurrected_threads; - resurrected_threads = tmp; - } - } - - /* Finally, we can update the blackhole_queue. This queue - * simply strings together TSOs blocked on black holes, it is - * not intended to keep anything alive. Hence, we do not follow - * pointers on the blackhole_queue until now, when we have - * determined which TSOs are otherwise reachable. We know at - * this point that all TSOs have been evacuated, however. - */ - { - StgTSO **pt; - for (pt = &blackhole_queue; *pt != END_TSO_QUEUE; pt = &((*pt)->link)) { - *pt = (StgTSO *)isAlive((StgClosure *)*pt); - ASSERT(*pt != NULL); - } - } - - weak_stage = WeakDone; // *now* we're done, - return rtsTrue; // but one more round of scavenging, please - - default: - barf("traverse_weak_ptr_list"); - return rtsTrue; - } - -} - -/* ----------------------------------------------------------------------------- - The blackhole queue - - Threads on this list behave like weak pointers during the normal - phase of garbage collection: if the blackhole is reachable, then - the thread is reachable too. - -------------------------------------------------------------------------- */ -static rtsBool -traverse_blackhole_queue (void) -{ - StgTSO *prev, *t, *tmp; - rtsBool flag; - - flag = rtsFalse; - prev = NULL; - - for (t = blackhole_queue; t != END_TSO_QUEUE; prev=t, t = t->link) { - if (! (tmp = (StgTSO *)isAlive((StgClosure*)t))) { - if (isAlive(t->block_info.closure)) { - t = (StgTSO *)evacuate((StgClosure *)t); - if (prev) prev->link = t; - flag = rtsTrue; - } - } - } - return flag; -} - -/* ----------------------------------------------------------------------------- - After GC, the live weak pointer list may have forwarding pointers - on it, because a weak pointer object was evacuated after being - moved to the live weak pointer list. We remove those forwarding - pointers here. - - Also, we don't consider weak pointer objects to be reachable, but - we must nevertheless consider them to be "live" and retain them. - Therefore any weak pointer objects which haven't as yet been - evacuated need to be evacuated now. - -------------------------------------------------------------------------- */ - - -static void -mark_weak_ptr_list ( StgWeak **list ) -{ - StgWeak *w, **last_w; - - last_w = list; - for (w = *list; w; w = w->link) { - // w might be WEAK, EVACUATED, or DEAD_WEAK (actually CON_STATIC) here - ASSERT(w->header.info == &stg_DEAD_WEAK_info - || get_itbl(w)->type == WEAK || get_itbl(w)->type == EVACUATED); - w = (StgWeak *)evacuate((StgClosure *)w); - *last_w = w; - last_w = &(w->link); - } -} - -/* ----------------------------------------------------------------------------- - isAlive determines whether the given closure is still alive (after - a garbage collection) or not. It returns the new address of the - closure if it is alive, or NULL otherwise. - - NOTE: Use it before compaction only! - -------------------------------------------------------------------------- */ - - -StgClosure * -isAlive(StgClosure *p) -{ - const StgInfoTable *info; - bdescr *bd; - - while (1) { - - ASSERT(LOOKS_LIKE_CLOSURE_PTR(p)); - info = get_itbl(p); - - // ignore static closures - // - // ToDo: for static closures, check the static link field. - // Problem here is that we sometimes don't set the link field, eg. - // for static closures with an empty SRT or CONSTR_STATIC_NOCAFs. - // - if (!HEAP_ALLOCED(p)) { - return p; - } - - // ignore closures in generations that we're not collecting. - bd = Bdescr((P_)p); - if (bd->gen_no > N) { - return p; - } - - // if it's a pointer into to-space, then we're done - if (bd->flags & BF_EVACUATED) { - return p; - } - - // large objects use the evacuated flag - if (bd->flags & BF_LARGE) { - return NULL; - } - - // check the mark bit for compacted steps - if ((bd->flags & BF_COMPACTED) && is_marked((P_)p,bd)) { - return p; - } - - switch (info->type) { - - case IND: - case IND_STATIC: - case IND_PERM: - case IND_OLDGEN: // rely on compatible layout with StgInd - case IND_OLDGEN_PERM: - // follow indirections - p = ((StgInd *)p)->indirectee; - continue; - - case EVACUATED: - // alive! - return ((StgEvacuated *)p)->evacuee; - - case TSO: - if (((StgTSO *)p)->what_next == ThreadRelocated) { - p = (StgClosure *)((StgTSO *)p)->link; - continue; - } - return NULL; - - default: - // dead. - return NULL; - } - } -} - -static void -mark_root(StgClosure **root) -{ - *root = evacuate(*root); -} - -STATIC_INLINE void -upd_evacuee(StgClosure *p, StgClosure *dest) -{ - // not true: (ToDo: perhaps it should be) - // ASSERT(Bdescr((P_)dest)->flags & BF_EVACUATED); - SET_INFO(p, &stg_EVACUATED_info); - ((StgEvacuated *)p)->evacuee = dest; -} - - -STATIC_INLINE StgClosure * -copy(StgClosure *src, nat size, step *stp) -{ - StgPtr to, from; - nat i; -#ifdef PROFILING - // @LDV profiling - nat size_org = size; -#endif - - TICK_GC_WORDS_COPIED(size); - /* Find out where we're going, using the handy "to" pointer in - * the step of the source object. If it turns out we need to - * evacuate to an older generation, adjust it here (see comment - * by evacuate()). - */ - if (stp->gen_no < evac_gen) { - if (eager_promotion) { - stp = &generations[evac_gen].steps[0]; - } else { - failed_to_evac = rtsTrue; - } - } - - /* chain a new block onto the to-space for the destination step if - * necessary. - */ - if (stp->hp + size >= stp->hpLim) { - gc_alloc_block(stp); - } - - to = stp->hp; - from = (StgPtr)src; - stp->hp = to + size; - for (i = 0; i < size; i++) { // unroll for small i - to[i] = from[i]; - } - upd_evacuee((StgClosure *)from,(StgClosure *)to); - -#ifdef PROFILING - // We store the size of the just evacuated object in the LDV word so that - // the profiler can guess the position of the next object later. - SET_EVACUAEE_FOR_LDV(from, size_org); -#endif - return (StgClosure *)to; -} - -// Same as copy() above, except the object will be allocated in memory -// that will not be scavenged. Used for object that have no pointer -// fields. -STATIC_INLINE StgClosure * -copy_noscav(StgClosure *src, nat size, step *stp) -{ - StgPtr to, from; - nat i; -#ifdef PROFILING - // @LDV profiling - nat size_org = size; -#endif - - TICK_GC_WORDS_COPIED(size); - /* Find out where we're going, using the handy "to" pointer in - * the step of the source object. If it turns out we need to - * evacuate to an older generation, adjust it here (see comment - * by evacuate()). - */ - if (stp->gen_no < evac_gen) { - if (eager_promotion) { - stp = &generations[evac_gen].steps[0]; - } else { - failed_to_evac = rtsTrue; - } - } - - /* chain a new block onto the to-space for the destination step if - * necessary. - */ - if (stp->scavd_hp + size >= stp->scavd_hpLim) { - gc_alloc_scavd_block(stp); - } - - to = stp->scavd_hp; - from = (StgPtr)src; - stp->scavd_hp = to + size; - for (i = 0; i < size; i++) { // unroll for small i - to[i] = from[i]; - } - upd_evacuee((StgClosure *)from,(StgClosure *)to); - -#ifdef PROFILING - // We store the size of the just evacuated object in the LDV word so that - // the profiler can guess the position of the next object later. - SET_EVACUAEE_FOR_LDV(from, size_org); -#endif - return (StgClosure *)to; -} - -/* Special version of copy() for when we only want to copy the info - * pointer of an object, but reserve some padding after it. This is - * used to optimise evacuation of BLACKHOLEs. - */ - - -static StgClosure * -copyPart(StgClosure *src, nat size_to_reserve, nat size_to_copy, step *stp) -{ - P_ dest, to, from; -#ifdef PROFILING - // @LDV profiling - nat size_to_copy_org = size_to_copy; -#endif - - TICK_GC_WORDS_COPIED(size_to_copy); - if (stp->gen_no < evac_gen) { - if (eager_promotion) { - stp = &generations[evac_gen].steps[0]; - } else { - failed_to_evac = rtsTrue; - } - } - - if (stp->hp + size_to_reserve >= stp->hpLim) { - gc_alloc_block(stp); - } - - for(to = stp->hp, from = (P_)src; size_to_copy>0; --size_to_copy) { - *to++ = *from++; - } - - dest = stp->hp; - stp->hp += size_to_reserve; - upd_evacuee(src,(StgClosure *)dest); -#ifdef PROFILING - // We store the size of the just evacuated object in the LDV word so that - // the profiler can guess the position of the next object later. - // size_to_copy_org is wrong because the closure already occupies size_to_reserve - // words. - SET_EVACUAEE_FOR_LDV(src, size_to_reserve); - // fill the slop - if (size_to_reserve - size_to_copy_org > 0) - LDV_FILL_SLOP(stp->hp - 1, (int)(size_to_reserve - size_to_copy_org)); -#endif - return (StgClosure *)dest; -} - - -/* ----------------------------------------------------------------------------- - Evacuate a large object - - This just consists of removing the object from the (doubly-linked) - step->large_objects list, and linking it on to the (singly-linked) - step->new_large_objects list, from where it will be scavenged later. - - Convention: bd->flags has BF_EVACUATED set for a large object - that has been evacuated, or unset otherwise. - -------------------------------------------------------------------------- */ - - -STATIC_INLINE void -evacuate_large(StgPtr p) -{ - bdescr *bd = Bdescr(p); - step *stp; - - // object must be at the beginning of the block (or be a ByteArray) - ASSERT(get_itbl((StgClosure *)p)->type == ARR_WORDS || - (((W_)p & BLOCK_MASK) == 0)); - - // already evacuated? - if (bd->flags & BF_EVACUATED) { - /* Don't forget to set the failed_to_evac flag if we didn't get - * the desired destination (see comments in evacuate()). - */ - if (bd->gen_no < evac_gen) { - failed_to_evac = rtsTrue; - TICK_GC_FAILED_PROMOTION(); - } - return; - } - - stp = bd->step; - // remove from large_object list - if (bd->u.back) { - bd->u.back->link = bd->link; - } else { // first object in the list - stp->large_objects = bd->link; - } - if (bd->link) { - bd->link->u.back = bd->u.back; - } - - /* link it on to the evacuated large object list of the destination step - */ - stp = bd->step->to; - if (stp->gen_no < evac_gen) { - if (eager_promotion) { - stp = &generations[evac_gen].steps[0]; - } else { - failed_to_evac = rtsTrue; - } - } - - bd->step = stp; - bd->gen_no = stp->gen_no; - bd->link = stp->new_large_objects; - stp->new_large_objects = bd; - bd->flags |= BF_EVACUATED; -} - -/* ----------------------------------------------------------------------------- - Evacuate - - This is called (eventually) for every live object in the system. - - The caller to evacuate specifies a desired generation in the - evac_gen global variable. The following conditions apply to - evacuating an object which resides in generation M when we're - collecting up to generation N - - if M >= evac_gen - if M > N do nothing - else evac to step->to - - if M < evac_gen evac to evac_gen, step 0 - - if the object is already evacuated, then we check which generation - it now resides in. - - if M >= evac_gen do nothing - if M < evac_gen set failed_to_evac flag to indicate that we - didn't manage to evacuate this object into evac_gen. - - - OPTIMISATION NOTES: - - evacuate() is the single most important function performance-wise - in the GC. Various things have been tried to speed it up, but as - far as I can tell the code generated by gcc 3.2 with -O2 is about - as good as it's going to get. We pass the argument to evacuate() - in a register using the 'regparm' attribute (see the prototype for - evacuate() near the top of this file). - - Changing evacuate() to take an (StgClosure **) rather than - returning the new pointer seems attractive, because we can avoid - writing back the pointer when it hasn't changed (eg. for a static - object, or an object in a generation > N). However, I tried it and - it doesn't help. One reason is that the (StgClosure **) pointer - gets spilled to the stack inside evacuate(), resulting in far more - extra reads/writes than we save. - -------------------------------------------------------------------------- */ - -REGPARM1 static StgClosure * -evacuate(StgClosure *q) -{ -#if defined(PAR) - StgClosure *to; -#endif - bdescr *bd = NULL; - step *stp; - const StgInfoTable *info; - -loop: - ASSERT(LOOKS_LIKE_CLOSURE_PTR(q)); - - if (!HEAP_ALLOCED(q)) { - - if (!major_gc) return q; - - info = get_itbl(q); - switch (info->type) { - - case THUNK_STATIC: - if (info->srt_bitmap != 0 && - *THUNK_STATIC_LINK((StgClosure *)q) == NULL) { - *THUNK_STATIC_LINK((StgClosure *)q) = static_objects; - static_objects = (StgClosure *)q; - } - return q; - - case FUN_STATIC: - if (info->srt_bitmap != 0 && - *FUN_STATIC_LINK((StgClosure *)q) == NULL) { - *FUN_STATIC_LINK((StgClosure *)q) = static_objects; - static_objects = (StgClosure *)q; - } - return q; - - case IND_STATIC: - /* If q->saved_info != NULL, then it's a revertible CAF - it'll be - * on the CAF list, so don't do anything with it here (we'll - * scavenge it later). - */ - if (((StgIndStatic *)q)->saved_info == NULL - && *IND_STATIC_LINK((StgClosure *)q) == NULL) { - *IND_STATIC_LINK((StgClosure *)q) = static_objects; - static_objects = (StgClosure *)q; - } - return q; - - case CONSTR_STATIC: - if (*STATIC_LINK(info,(StgClosure *)q) == NULL) { - *STATIC_LINK(info,(StgClosure *)q) = static_objects; - static_objects = (StgClosure *)q; - } - return q; - - case CONSTR_NOCAF_STATIC: - /* no need to put these on the static linked list, they don't need - * to be scavenged. - */ - return q; - - default: - barf("evacuate(static): strange closure type %d", (int)(info->type)); - } - } - - bd = Bdescr((P_)q); - - if (bd->gen_no > N) { - /* Can't evacuate this object, because it's in a generation - * older than the ones we're collecting. Let's hope that it's - * in evac_gen or older, or we will have to arrange to track - * this pointer using the mutable list. - */ - if (bd->gen_no < evac_gen) { - // nope - failed_to_evac = rtsTrue; - TICK_GC_FAILED_PROMOTION(); - } - return q; - } - - if ((bd->flags & (BF_LARGE | BF_COMPACTED | BF_EVACUATED)) != 0) { - - /* pointer into to-space: just return it. This normally - * shouldn't happen, but alllowing it makes certain things - * slightly easier (eg. the mutable list can contain the same - * object twice, for example). - */ - if (bd->flags & BF_EVACUATED) { - if (bd->gen_no < evac_gen) { - failed_to_evac = rtsTrue; - TICK_GC_FAILED_PROMOTION(); - } - return q; - } - - /* evacuate large objects by re-linking them onto a different list. - */ - if (bd->flags & BF_LARGE) { - info = get_itbl(q); - if (info->type == TSO && - ((StgTSO *)q)->what_next == ThreadRelocated) { - q = (StgClosure *)((StgTSO *)q)->link; - goto loop; - } - evacuate_large((P_)q); - return q; - } - - /* If the object is in a step that we're compacting, then we - * need to use an alternative evacuate procedure. - */ - if (bd->flags & BF_COMPACTED) { - if (!is_marked((P_)q,bd)) { - mark((P_)q,bd); - if (mark_stack_full()) { - mark_stack_overflowed = rtsTrue; - reset_mark_stack(); - } - push_mark_stack((P_)q); - } - return q; - } - } - - stp = bd->step->to; - - info = get_itbl(q); - - switch (info->type) { - - case MUT_VAR_CLEAN: - case MUT_VAR_DIRTY: - case MVAR: - return copy(q,sizeW_fromITBL(info),stp); - - case CONSTR_0_1: - { - StgWord w = (StgWord)q->payload[0]; - if (q->header.info == Czh_con_info && - // unsigned, so always true: (StgChar)w >= MIN_CHARLIKE && - (StgChar)w <= MAX_CHARLIKE) { - return (StgClosure *)CHARLIKE_CLOSURE((StgChar)w); - } - if (q->header.info == Izh_con_info && - (StgInt)w >= MIN_INTLIKE && (StgInt)w <= MAX_INTLIKE) { - return (StgClosure *)INTLIKE_CLOSURE((StgInt)w); - } - // else - return copy_noscav(q,sizeofW(StgHeader)+1,stp); - } - - case FUN_0_1: - case FUN_1_0: - case CONSTR_1_0: - return copy(q,sizeofW(StgHeader)+1,stp); - - case THUNK_1_0: - case THUNK_0_1: - return copy(q,sizeofW(StgThunk)+1,stp); - - case THUNK_1_1: - case THUNK_2_0: - case THUNK_0_2: -#ifdef NO_PROMOTE_THUNKS - if (bd->gen_no == 0 && - bd->step->no != 0 && - bd->step->no == generations[bd->gen_no].n_steps-1) { - stp = bd->step; - } -#endif - return copy(q,sizeofW(StgThunk)+2,stp); - - case FUN_1_1: - case FUN_2_0: - case CONSTR_1_1: - case CONSTR_2_0: - case FUN_0_2: - return copy(q,sizeofW(StgHeader)+2,stp); - - case CONSTR_0_2: - return copy_noscav(q,sizeofW(StgHeader)+2,stp); - - case THUNK: - return copy(q,thunk_sizeW_fromITBL(info),stp); - - case FUN: - case CONSTR: - case IND_PERM: - case IND_OLDGEN_PERM: - case WEAK: - case STABLE_NAME: - return copy(q,sizeW_fromITBL(info),stp); - - case BCO: - return copy(q,bco_sizeW((StgBCO *)q),stp); - - case CAF_BLACKHOLE: - case SE_CAF_BLACKHOLE: - case SE_BLACKHOLE: - case BLACKHOLE: - return copyPart(q,BLACKHOLE_sizeW(),sizeofW(StgHeader),stp); - - case THUNK_SELECTOR: - { - StgClosure *p; - const StgInfoTable *info_ptr; - - if (thunk_selector_depth > MAX_THUNK_SELECTOR_DEPTH) { - return copy(q,THUNK_SELECTOR_sizeW(),stp); - } - - // stashed away for LDV profiling, see below - info_ptr = q->header.info; - - p = eval_thunk_selector(info->layout.selector_offset, - (StgSelector *)q); - - if (p == NULL) { - return copy(q,THUNK_SELECTOR_sizeW(),stp); - } else { - StgClosure *val; - // q is still BLACKHOLE'd. - thunk_selector_depth++; - val = evacuate(p); - thunk_selector_depth--; - -#ifdef PROFILING - // For the purposes of LDV profiling, we have destroyed - // the original selector thunk. - SET_INFO(q, info_ptr); - LDV_RECORD_DEAD_FILL_SLOP_DYNAMIC(q); -#endif - - // Update the THUNK_SELECTOR with an indirection to the - // EVACUATED closure now at p. Why do this rather than - // upd_evacuee(q,p)? Because we have an invariant that an - // EVACUATED closure always points to an object in the - // same or an older generation (required by the short-cut - // test in the EVACUATED case, below). - SET_INFO(q, &stg_IND_info); - ((StgInd *)q)->indirectee = p; - - // For the purposes of LDV profiling, we have created an - // indirection. - LDV_RECORD_CREATE(q); - - return val; - } - } - - case IND: - case IND_OLDGEN: - // follow chains of indirections, don't evacuate them - q = ((StgInd*)q)->indirectee; - goto loop; - - case RET_BCO: - case RET_SMALL: - case RET_VEC_SMALL: - case RET_BIG: - case RET_VEC_BIG: - case RET_DYN: - case UPDATE_FRAME: - case STOP_FRAME: - case CATCH_FRAME: - case CATCH_STM_FRAME: - case CATCH_RETRY_FRAME: - case ATOMICALLY_FRAME: - // shouldn't see these - barf("evacuate: stack frame at %p\n", q); - - case PAP: - return copy(q,pap_sizeW((StgPAP*)q),stp); - - case AP: - return copy(q,ap_sizeW((StgAP*)q),stp); - - case AP_STACK: - return copy(q,ap_stack_sizeW((StgAP_STACK*)q),stp); - - case EVACUATED: - /* Already evacuated, just return the forwarding address. - * HOWEVER: if the requested destination generation (evac_gen) is - * older than the actual generation (because the object was - * already evacuated to a younger generation) then we have to - * set the failed_to_evac flag to indicate that we couldn't - * manage to promote the object to the desired generation. - */ - /* - * Optimisation: the check is fairly expensive, but we can often - * shortcut it if either the required generation is 0, or the - * current object (the EVACUATED) is in a high enough generation. - * We know that an EVACUATED always points to an object in the - * same or an older generation. stp is the lowest step that the - * current object would be evacuated to, so we only do the full - * check if stp is too low. - */ - if (evac_gen > 0 && stp->gen_no < evac_gen) { // optimisation - StgClosure *p = ((StgEvacuated*)q)->evacuee; - if (HEAP_ALLOCED(p) && Bdescr((P_)p)->gen_no < evac_gen) { - failed_to_evac = rtsTrue; - TICK_GC_FAILED_PROMOTION(); - } - } - return ((StgEvacuated*)q)->evacuee; - - case ARR_WORDS: - // just copy the block - return copy_noscav(q,arr_words_sizeW((StgArrWords *)q),stp); - - case MUT_ARR_PTRS_CLEAN: - case MUT_ARR_PTRS_DIRTY: - case MUT_ARR_PTRS_FROZEN: - case MUT_ARR_PTRS_FROZEN0: - // just copy the block - return copy(q,mut_arr_ptrs_sizeW((StgMutArrPtrs *)q),stp); - - case TSO: - { - StgTSO *tso = (StgTSO *)q; - - /* Deal with redirected TSOs (a TSO that's had its stack enlarged). - */ - if (tso->what_next == ThreadRelocated) { - q = (StgClosure *)tso->link; - goto loop; - } - - /* To evacuate a small TSO, we need to relocate the update frame - * list it contains. - */ - { - StgTSO *new_tso; - StgPtr p, q; - - new_tso = (StgTSO *)copyPart((StgClosure *)tso, - tso_sizeW(tso), - sizeofW(StgTSO), stp); - move_TSO(tso, new_tso); - for (p = tso->sp, q = new_tso->sp; - p < tso->stack+tso->stack_size;) { - *q++ = *p++; - } - - return (StgClosure *)new_tso; - } - } - -#if defined(PAR) - case RBH: - { - //StgInfoTable *rip = get_closure_info(q, &size, &ptrs, &nonptrs, &vhs, str); - to = copy(q,BLACKHOLE_sizeW(),stp); - //ToDo: derive size etc from reverted IP - //to = copy(q,size,stp); - debugTrace(DEBUG_gc, "evacuate: RBH %p (%s) to %p (%s)", - q, info_type(q), to, info_type(to)); - return to; - } - - case BLOCKED_FETCH: - ASSERT(sizeofW(StgBlockedFetch) >= MIN_PAYLOD_SIZE); - to = copy(q,sizeofW(StgBlockedFetch),stp); - debugTrace(DEBUG_gc, "evacuate: %p (%s) to %p (%s)", - q, info_type(q), to, info_type(to)); - return to; - -# ifdef DIST - case REMOTE_REF: -# endif - case FETCH_ME: - ASSERT(sizeofW(StgBlockedFetch) >= MIN_PAYLOAD_SIZE); - to = copy(q,sizeofW(StgFetchMe),stp); - debugTrace(DEBUG_gc, "evacuate: %p (%s) to %p (%s)", - q, info_type(q), to, info_type(to))); - return to; - - case FETCH_ME_BQ: - ASSERT(sizeofW(StgBlockedFetch) >= MIN_PAYLOAD_SIZE); - to = copy(q,sizeofW(StgFetchMeBlockingQueue),stp); - debugTrace(DEBUG_gc, "evacuate: %p (%s) to %p (%s)", - q, info_type(q), to, info_type(to))); - return to; -#endif - - case TREC_HEADER: - return copy(q,sizeofW(StgTRecHeader),stp); - - case TVAR_WATCH_QUEUE: - return copy(q,sizeofW(StgTVarWatchQueue),stp); - - case TVAR: - return copy(q,sizeofW(StgTVar),stp); - - case TREC_CHUNK: - return copy(q,sizeofW(StgTRecChunk),stp); - - case ATOMIC_INVARIANT: - return copy(q,sizeofW(StgAtomicInvariant),stp); - - case INVARIANT_CHECK_QUEUE: - return copy(q,sizeofW(StgInvariantCheckQueue),stp); - - default: - barf("evacuate: strange closure type %d", (int)(info->type)); - } - - barf("evacuate"); -} - -/* ----------------------------------------------------------------------------- - Evaluate a THUNK_SELECTOR if possible. - - returns: NULL if we couldn't evaluate this THUNK_SELECTOR, or - a closure pointer if we evaluated it and this is the result. Note - that "evaluating" the THUNK_SELECTOR doesn't necessarily mean - reducing it to HNF, just that we have eliminated the selection. - The result might be another thunk, or even another THUNK_SELECTOR. - - If the return value is non-NULL, the original selector thunk has - been BLACKHOLE'd, and should be updated with an indirection or a - forwarding pointer. If the return value is NULL, then the selector - thunk is unchanged. - - *** - ToDo: the treatment of THUNK_SELECTORS could be improved in the - following way (from a suggestion by Ian Lynagh): - - We can have a chain like this: - - sel_0 --> (a,b) - | - |-----> sel_0 --> (a,b) - | - |-----> sel_0 --> ... - - and the depth limit means we don't go all the way to the end of the - chain, which results in a space leak. This affects the recursive - call to evacuate() in the THUNK_SELECTOR case in evacuate(): *not* - the recursive call to eval_thunk_selector() in - eval_thunk_selector(). - - We could eliminate the depth bound in this case, in the following - way: - - - traverse the chain once to discover the *value* of the - THUNK_SELECTOR. Mark all THUNK_SELECTORS that we - visit on the way as having been visited already (somehow). - - - in a second pass, traverse the chain again updating all - THUNK_SEELCTORS that we find on the way with indirections to - the value. - - - if we encounter a "marked" THUNK_SELECTOR in a normal - evacuate(), we konw it can't be updated so just evac it. - - Program that illustrates the problem: - - foo [] = ([], []) - foo (x:xs) = let (ys, zs) = foo xs - in if x >= 0 then (x:ys, zs) else (ys, x:zs) - - main = bar [1..(100000000::Int)] - bar xs = (\(ys, zs) -> print ys >> print zs) (foo xs) - - -------------------------------------------------------------------------- */ - -static inline rtsBool -is_to_space ( StgClosure *p ) -{ - bdescr *bd; - - bd = Bdescr((StgPtr)p); - if (HEAP_ALLOCED(p) && - ((bd->flags & BF_EVACUATED) - || ((bd->flags & BF_COMPACTED) && - is_marked((P_)p,bd)))) { - return rtsTrue; - } else { - return rtsFalse; - } -} - -static StgClosure * -eval_thunk_selector( nat field, StgSelector * p ) -{ - StgInfoTable *info; - const StgInfoTable *info_ptr; - StgClosure *selectee; - - selectee = p->selectee; - - // Save the real info pointer (NOTE: not the same as get_itbl()). - info_ptr = p->header.info; - - // If the THUNK_SELECTOR is in a generation that we are not - // collecting, then bail out early. We won't be able to save any - // space in any case, and updating with an indirection is trickier - // in an old gen. - if (Bdescr((StgPtr)p)->gen_no > N) { - return NULL; - } - - // BLACKHOLE the selector thunk, since it is now under evaluation. - // This is important to stop us going into an infinite loop if - // this selector thunk eventually refers to itself. - SET_INFO(p,&stg_BLACKHOLE_info); - -selector_loop: - - // We don't want to end up in to-space, because this causes - // problems when the GC later tries to evacuate the result of - // eval_thunk_selector(). There are various ways this could - // happen: - // - // 1. following an IND_STATIC - // - // 2. when the old generation is compacted, the mark phase updates - // from-space pointers to be to-space pointers, and we can't - // reliably tell which we're following (eg. from an IND_STATIC). - // - // 3. compacting GC again: if we're looking at a constructor in - // the compacted generation, it might point directly to objects - // in to-space. We must bale out here, otherwise doing the selection - // will result in a to-space pointer being returned. - // - // (1) is dealt with using a BF_EVACUATED test on the - // selectee. (2) and (3): we can tell if we're looking at an - // object in the compacted generation that might point to - // to-space objects by testing that (a) it is BF_COMPACTED, (b) - // the compacted generation is being collected, and (c) the - // object is marked. Only a marked object may have pointers that - // point to to-space objects, because that happens when - // scavenging. - // - // The to-space test is now embodied in the in_to_space() inline - // function, as it is re-used below. - // - if (is_to_space(selectee)) { - goto bale_out; - } - - info = get_itbl(selectee); - switch (info->type) { - case CONSTR: - case CONSTR_1_0: - case CONSTR_0_1: - case CONSTR_2_0: - case CONSTR_1_1: - case CONSTR_0_2: - case CONSTR_STATIC: - case CONSTR_NOCAF_STATIC: - // check that the size is in range - ASSERT(field < (StgWord32)(info->layout.payload.ptrs + - info->layout.payload.nptrs)); - - // Select the right field from the constructor, and check - // that the result isn't in to-space. It might be in - // to-space if, for example, this constructor contains - // pointers to younger-gen objects (and is on the mut-once - // list). - // - { - StgClosure *q; - q = selectee->payload[field]; - if (is_to_space(q)) { - goto bale_out; - } else { - return q; - } - } - - case IND: - case IND_PERM: - case IND_OLDGEN: - case IND_OLDGEN_PERM: - case IND_STATIC: - selectee = ((StgInd *)selectee)->indirectee; - goto selector_loop; - - case EVACUATED: - // We don't follow pointers into to-space; the constructor - // has already been evacuated, so we won't save any space - // leaks by evaluating this selector thunk anyhow. - break; - - case THUNK_SELECTOR: - { - StgClosure *val; - - // check that we don't recurse too much, re-using the - // depth bound also used in evacuate(). - if (thunk_selector_depth >= MAX_THUNK_SELECTOR_DEPTH) { - break; - } - thunk_selector_depth++; - - val = eval_thunk_selector(info->layout.selector_offset, - (StgSelector *)selectee); - - thunk_selector_depth--; - - if (val == NULL) { - break; - } else { - // We evaluated this selector thunk, so update it with - // an indirection. NOTE: we don't use UPD_IND here, - // because we are guaranteed that p is in a generation - // that we are collecting, and we never want to put the - // indirection on a mutable list. -#ifdef PROFILING - // For the purposes of LDV profiling, we have destroyed - // the original selector thunk. - SET_INFO(p, info_ptr); - LDV_RECORD_DEAD_FILL_SLOP_DYNAMIC(selectee); -#endif - ((StgInd *)selectee)->indirectee = val; - SET_INFO(selectee,&stg_IND_info); - - // For the purposes of LDV profiling, we have created an - // indirection. - LDV_RECORD_CREATE(selectee); - - selectee = val; - goto selector_loop; - } - } - - case AP: - case AP_STACK: - case THUNK: - case THUNK_1_0: - case THUNK_0_1: - case THUNK_2_0: - case THUNK_1_1: - case THUNK_0_2: - case THUNK_STATIC: - case CAF_BLACKHOLE: - case SE_CAF_BLACKHOLE: - case SE_BLACKHOLE: - case BLACKHOLE: -#if defined(PAR) - case RBH: - case BLOCKED_FETCH: -# ifdef DIST - case REMOTE_REF: -# endif - case FETCH_ME: - case FETCH_ME_BQ: -#endif - // not evaluated yet - break; - - default: - barf("eval_thunk_selector: strange selectee %d", - (int)(info->type)); - } - -bale_out: - // We didn't manage to evaluate this thunk; restore the old info pointer - SET_INFO(p, info_ptr); - return NULL; -} - -/* ----------------------------------------------------------------------------- - move_TSO is called to update the TSO structure after it has been - moved from one place to another. - -------------------------------------------------------------------------- */ - -void -move_TSO (StgTSO *src, StgTSO *dest) -{ - ptrdiff_t diff; - - // relocate the stack pointer... - diff = (StgPtr)dest - (StgPtr)src; // In *words* - dest->sp = (StgPtr)dest->sp + diff; -} - -/* Similar to scavenge_large_bitmap(), but we don't write back the - * pointers we get back from evacuate(). - */ -static void -scavenge_large_srt_bitmap( StgLargeSRT *large_srt ) -{ - nat i, b, size; - StgWord bitmap; - StgClosure **p; - - b = 0; - bitmap = large_srt->l.bitmap[b]; - size = (nat)large_srt->l.size; - p = (StgClosure **)large_srt->srt; - for (i = 0; i < size; ) { - if ((bitmap & 1) != 0) { - evacuate(*p); - } - i++; - p++; - if (i % BITS_IN(W_) == 0) { - b++; - bitmap = large_srt->l.bitmap[b]; - } else { - bitmap = bitmap >> 1; - } - } -} - -/* evacuate the SRT. If srt_bitmap is zero, then there isn't an - * srt field in the info table. That's ok, because we'll - * never dereference it. - */ -STATIC_INLINE void -scavenge_srt (StgClosure **srt, nat srt_bitmap) -{ - nat bitmap; - StgClosure **p; - - bitmap = srt_bitmap; - p = srt; - - if (bitmap == (StgHalfWord)(-1)) { - scavenge_large_srt_bitmap( (StgLargeSRT *)srt ); - return; - } - - while (bitmap != 0) { - if ((bitmap & 1) != 0) { -#ifdef ENABLE_WIN32_DLL_SUPPORT - // Special-case to handle references to closures hiding out in DLLs, since - // double indirections required to get at those. The code generator knows - // which is which when generating the SRT, so it stores the (indirect) - // reference to the DLL closure in the table by first adding one to it. - // We check for this here, and undo the addition before evacuating it. - // - // If the SRT entry hasn't got bit 0 set, the SRT entry points to a - // closure that's fixed at link-time, and no extra magic is required. - if ( (unsigned long)(*srt) & 0x1 ) { - evacuate(*stgCast(StgClosure**,(stgCast(unsigned long, *srt) & ~0x1))); - } else { - evacuate(*p); - } -#else - evacuate(*p); -#endif - } - p++; - bitmap = bitmap >> 1; - } -} - - -STATIC_INLINE void -scavenge_thunk_srt(const StgInfoTable *info) -{ - StgThunkInfoTable *thunk_info; - - if (!major_gc) return; - - thunk_info = itbl_to_thunk_itbl(info); - scavenge_srt((StgClosure **)GET_SRT(thunk_info), thunk_info->i.srt_bitmap); -} - -STATIC_INLINE void -scavenge_fun_srt(const StgInfoTable *info) -{ - StgFunInfoTable *fun_info; - - if (!major_gc) return; - - fun_info = itbl_to_fun_itbl(info); - scavenge_srt((StgClosure **)GET_FUN_SRT(fun_info), fun_info->i.srt_bitmap); -} - -/* ----------------------------------------------------------------------------- - Scavenge a TSO. - -------------------------------------------------------------------------- */ - -static void -scavengeTSO (StgTSO *tso) -{ - if ( tso->why_blocked == BlockedOnMVar - || tso->why_blocked == BlockedOnBlackHole - || tso->why_blocked == BlockedOnException -#if defined(PAR) - || tso->why_blocked == BlockedOnGA - || tso->why_blocked == BlockedOnGA_NoSend -#endif - ) { - tso->block_info.closure = evacuate(tso->block_info.closure); - } - tso->blocked_exceptions = - (StgTSO *)evacuate((StgClosure *)tso->blocked_exceptions); - - // We don't always chase the link field: TSOs on the blackhole - // queue are not automatically alive, so the link field is a - // "weak" pointer in that case. - if (tso->why_blocked != BlockedOnBlackHole) { - tso->link = (StgTSO *)evacuate((StgClosure *)tso->link); - } - - // scavange current transaction record - tso->trec = (StgTRecHeader *)evacuate((StgClosure *)tso->trec); - - // scavenge this thread's stack - scavenge_stack(tso->sp, &(tso->stack[tso->stack_size])); -} - -/* ----------------------------------------------------------------------------- - Blocks of function args occur on the stack (at the top) and - in PAPs. - -------------------------------------------------------------------------- */ - -STATIC_INLINE StgPtr -scavenge_arg_block (StgFunInfoTable *fun_info, StgClosure **args) -{ - StgPtr p; - StgWord bitmap; - nat size; - - p = (StgPtr)args; - switch (fun_info->f.fun_type) { - case ARG_GEN: - bitmap = BITMAP_BITS(fun_info->f.b.bitmap); - size = BITMAP_SIZE(fun_info->f.b.bitmap); - goto small_bitmap; - case ARG_GEN_BIG: - size = GET_FUN_LARGE_BITMAP(fun_info)->size; - scavenge_large_bitmap(p, GET_FUN_LARGE_BITMAP(fun_info), size); - p += size; - break; - default: - bitmap = BITMAP_BITS(stg_arg_bitmaps[fun_info->f.fun_type]); - size = BITMAP_SIZE(stg_arg_bitmaps[fun_info->f.fun_type]); - small_bitmap: - while (size > 0) { - if ((bitmap & 1) == 0) { - *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); - } - p++; - bitmap = bitmap >> 1; - size--; - } - break; - } - return p; -} - -STATIC_INLINE StgPtr -scavenge_PAP_payload (StgClosure *fun, StgClosure **payload, StgWord size) -{ - StgPtr p; - StgWord bitmap; - StgFunInfoTable *fun_info; - - fun_info = get_fun_itbl(fun); - ASSERT(fun_info->i.type != PAP); - p = (StgPtr)payload; - - switch (fun_info->f.fun_type) { - case ARG_GEN: - bitmap = BITMAP_BITS(fun_info->f.b.bitmap); - goto small_bitmap; - case ARG_GEN_BIG: - scavenge_large_bitmap(p, GET_FUN_LARGE_BITMAP(fun_info), size); - p += size; - break; - case ARG_BCO: - scavenge_large_bitmap((StgPtr)payload, BCO_BITMAP(fun), size); - p += size; - break; - default: - bitmap = BITMAP_BITS(stg_arg_bitmaps[fun_info->f.fun_type]); - small_bitmap: - while (size > 0) { - if ((bitmap & 1) == 0) { - *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); - } - p++; - bitmap = bitmap >> 1; - size--; - } - break; - } - return p; -} - -STATIC_INLINE StgPtr -scavenge_PAP (StgPAP *pap) -{ - pap->fun = evacuate(pap->fun); - return scavenge_PAP_payload (pap->fun, pap->payload, pap->n_args); -} - -STATIC_INLINE StgPtr -scavenge_AP (StgAP *ap) -{ - ap->fun = evacuate(ap->fun); - return scavenge_PAP_payload (ap->fun, ap->payload, ap->n_args); -} - -/* ----------------------------------------------------------------------------- - Scavenge a given step until there are no more objects in this step - to scavenge. - - evac_gen is set by the caller to be either zero (for a step in a - generation < N) or G where G is the generation of the step being - scavenged. - - We sometimes temporarily change evac_gen back to zero if we're - scavenging a mutable object where early promotion isn't such a good - idea. - -------------------------------------------------------------------------- */ - -static void -scavenge(step *stp) -{ - StgPtr p, q; - StgInfoTable *info; - bdescr *bd; - nat saved_evac_gen = evac_gen; - - p = stp->scan; - bd = stp->scan_bd; - - failed_to_evac = rtsFalse; - - /* scavenge phase - standard breadth-first scavenging of the - * evacuated objects - */ - - while (bd != stp->hp_bd || p < stp->hp) { - - // If we're at the end of this block, move on to the next block - if (bd != stp->hp_bd && p == bd->free) { - bd = bd->link; - p = bd->start; - continue; - } - - ASSERT(LOOKS_LIKE_CLOSURE_PTR(p)); - info = get_itbl((StgClosure *)p); - - ASSERT(thunk_selector_depth == 0); - - q = p; - switch (info->type) { - - case MVAR: - { - StgMVar *mvar = ((StgMVar *)p); - evac_gen = 0; - mvar->head = (StgTSO *)evacuate((StgClosure *)mvar->head); - mvar->tail = (StgTSO *)evacuate((StgClosure *)mvar->tail); - mvar->value = evacuate((StgClosure *)mvar->value); - evac_gen = saved_evac_gen; - failed_to_evac = rtsTrue; // mutable. - p += sizeofW(StgMVar); - break; - } - - case FUN_2_0: - scavenge_fun_srt(info); - ((StgClosure *)p)->payload[1] = evacuate(((StgClosure *)p)->payload[1]); - ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]); - p += sizeofW(StgHeader) + 2; - break; - - case THUNK_2_0: - scavenge_thunk_srt(info); - ((StgThunk *)p)->payload[1] = evacuate(((StgThunk *)p)->payload[1]); - ((StgThunk *)p)->payload[0] = evacuate(((StgThunk *)p)->payload[0]); - p += sizeofW(StgThunk) + 2; - break; - - case CONSTR_2_0: - ((StgClosure *)p)->payload[1] = evacuate(((StgClosure *)p)->payload[1]); - ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]); - p += sizeofW(StgHeader) + 2; - break; - - case THUNK_1_0: - scavenge_thunk_srt(info); - ((StgThunk *)p)->payload[0] = evacuate(((StgThunk *)p)->payload[0]); - p += sizeofW(StgThunk) + 1; - break; - - case FUN_1_0: - scavenge_fun_srt(info); - case CONSTR_1_0: - ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]); - p += sizeofW(StgHeader) + 1; - break; - - case THUNK_0_1: - scavenge_thunk_srt(info); - p += sizeofW(StgThunk) + 1; - break; - - case FUN_0_1: - scavenge_fun_srt(info); - case CONSTR_0_1: - p += sizeofW(StgHeader) + 1; - break; - - case THUNK_0_2: - scavenge_thunk_srt(info); - p += sizeofW(StgThunk) + 2; - break; - - case FUN_0_2: - scavenge_fun_srt(info); - case CONSTR_0_2: - p += sizeofW(StgHeader) + 2; - break; - - case THUNK_1_1: - scavenge_thunk_srt(info); - ((StgThunk *)p)->payload[0] = evacuate(((StgThunk *)p)->payload[0]); - p += sizeofW(StgThunk) + 2; - break; - - case FUN_1_1: - scavenge_fun_srt(info); - case CONSTR_1_1: - ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]); - p += sizeofW(StgHeader) + 2; - break; - - case FUN: - scavenge_fun_srt(info); - goto gen_obj; - - case THUNK: - { - StgPtr end; - - scavenge_thunk_srt(info); - end = (P_)((StgThunk *)p)->payload + info->layout.payload.ptrs; - for (p = (P_)((StgThunk *)p)->payload; p < end; p++) { - *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); - } - p += info->layout.payload.nptrs; - break; - } - - gen_obj: - case CONSTR: - case WEAK: - case STABLE_NAME: - { - StgPtr end; - - end = (P_)((StgClosure *)p)->payload + info->layout.payload.ptrs; - for (p = (P_)((StgClosure *)p)->payload; p < end; p++) { - *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); - } - p += info->layout.payload.nptrs; - break; - } - - case BCO: { - StgBCO *bco = (StgBCO *)p; - bco->instrs = (StgArrWords *)evacuate((StgClosure *)bco->instrs); - bco->literals = (StgArrWords *)evacuate((StgClosure *)bco->literals); - bco->ptrs = (StgMutArrPtrs *)evacuate((StgClosure *)bco->ptrs); - bco->itbls = (StgArrWords *)evacuate((StgClosure *)bco->itbls); - p += bco_sizeW(bco); - break; - } - - case IND_PERM: - if (stp->gen->no != 0) { -#ifdef PROFILING - // @LDV profiling - // No need to call LDV_recordDead_FILL_SLOP_DYNAMIC() because an - // IND_OLDGEN_PERM closure is larger than an IND_PERM closure. - LDV_recordDead((StgClosure *)p, sizeofW(StgInd)); -#endif - // - // Todo: maybe use SET_HDR() and remove LDV_RECORD_CREATE()? - // - SET_INFO(((StgClosure *)p), &stg_IND_OLDGEN_PERM_info); - - // We pretend that p has just been created. - LDV_RECORD_CREATE((StgClosure *)p); - } - // fall through - case IND_OLDGEN_PERM: - ((StgInd *)p)->indirectee = evacuate(((StgInd *)p)->indirectee); - p += sizeofW(StgInd); - break; - - case MUT_VAR_CLEAN: - case MUT_VAR_DIRTY: { - rtsBool saved_eager_promotion = eager_promotion; - - eager_promotion = rtsFalse; - ((StgMutVar *)p)->var = evacuate(((StgMutVar *)p)->var); - eager_promotion = saved_eager_promotion; - - if (failed_to_evac) { - ((StgClosure *)q)->header.info = &stg_MUT_VAR_DIRTY_info; - } else { - ((StgClosure *)q)->header.info = &stg_MUT_VAR_CLEAN_info; - } - p += sizeofW(StgMutVar); - break; - } - - case CAF_BLACKHOLE: - case SE_CAF_BLACKHOLE: - case SE_BLACKHOLE: - case BLACKHOLE: - p += BLACKHOLE_sizeW(); - break; - - case THUNK_SELECTOR: - { - StgSelector *s = (StgSelector *)p; - s->selectee = evacuate(s->selectee); - p += THUNK_SELECTOR_sizeW(); - break; - } - - // A chunk of stack saved in a heap object - case AP_STACK: - { - StgAP_STACK *ap = (StgAP_STACK *)p; - - ap->fun = evacuate(ap->fun); - scavenge_stack((StgPtr)ap->payload, (StgPtr)ap->payload + ap->size); - p = (StgPtr)ap->payload + ap->size; - break; - } - - case PAP: - p = scavenge_PAP((StgPAP *)p); - break; - - case AP: - p = scavenge_AP((StgAP *)p); - break; - - case ARR_WORDS: - // nothing to follow - p += arr_words_sizeW((StgArrWords *)p); - break; - - case MUT_ARR_PTRS_CLEAN: - case MUT_ARR_PTRS_DIRTY: - // follow everything - { - StgPtr next; - rtsBool saved_eager; - - // We don't eagerly promote objects pointed to by a mutable - // array, but if we find the array only points to objects in - // the same or an older generation, we mark it "clean" and - // avoid traversing it during minor GCs. - saved_eager = eager_promotion; - eager_promotion = rtsFalse; - next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p); - for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) { - *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); - } - eager_promotion = saved_eager; - - if (failed_to_evac) { - ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_DIRTY_info; - } else { - ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_CLEAN_info; - } - - failed_to_evac = rtsTrue; // always put it on the mutable list. - break; - } - - case MUT_ARR_PTRS_FROZEN: - case MUT_ARR_PTRS_FROZEN0: - // follow everything - { - StgPtr next; - - next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p); - for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) { - *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); - } - - // If we're going to put this object on the mutable list, then - // set its info ptr to MUT_ARR_PTRS_FROZEN0 to indicate that. - if (failed_to_evac) { - ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_FROZEN0_info; - } else { - ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_FROZEN_info; - } - break; - } - - case TSO: - { - StgTSO *tso = (StgTSO *)p; - rtsBool saved_eager = eager_promotion; - - eager_promotion = rtsFalse; - scavengeTSO(tso); - eager_promotion = saved_eager; - - if (failed_to_evac) { - tso->flags |= TSO_DIRTY; - } else { - tso->flags &= ~TSO_DIRTY; - } - - failed_to_evac = rtsTrue; // always on the mutable list - p += tso_sizeW(tso); - break; - } - -#if defined(PAR) - case RBH: - { -#if 0 - nat size, ptrs, nonptrs, vhs; - char str[80]; - StgInfoTable *rip = get_closure_info(p, &size, &ptrs, &nonptrs, &vhs, str); -#endif - StgRBH *rbh = (StgRBH *)p; - (StgClosure *)rbh->blocking_queue = - evacuate((StgClosure *)rbh->blocking_queue); - failed_to_evac = rtsTrue; // mutable anyhow. - debugTrace(DEBUG_gc, "scavenge: RBH %p (%s) (new blocking_queue link=%p)", - p, info_type(p), (StgClosure *)rbh->blocking_queue); - // ToDo: use size of reverted closure here! - p += BLACKHOLE_sizeW(); - break; - } - - case BLOCKED_FETCH: - { - StgBlockedFetch *bf = (StgBlockedFetch *)p; - // follow the pointer to the node which is being demanded - (StgClosure *)bf->node = - evacuate((StgClosure *)bf->node); - // follow the link to the rest of the blocking queue - (StgClosure *)bf->link = - evacuate((StgClosure *)bf->link); - debugTrace(DEBUG_gc, "scavenge: %p (%s); node is now %p; exciting, isn't it", - bf, info_type((StgClosure *)bf), - bf->node, info_type(bf->node))); - p += sizeofW(StgBlockedFetch); - break; - } - -#ifdef DIST - case REMOTE_REF: -#endif - case FETCH_ME: - p += sizeofW(StgFetchMe); - break; // nothing to do in this case - - case FETCH_ME_BQ: - { - StgFetchMeBlockingQueue *fmbq = (StgFetchMeBlockingQueue *)p; - (StgClosure *)fmbq->blocking_queue = - evacuate((StgClosure *)fmbq->blocking_queue); - debugTrace(DEBUG_gc, "scavenge: %p (%s) exciting, isn't it", - p, info_type((StgClosure *)p))); - p += sizeofW(StgFetchMeBlockingQueue); - break; - } -#endif - - case TVAR_WATCH_QUEUE: - { - StgTVarWatchQueue *wq = ((StgTVarWatchQueue *) p); - evac_gen = 0; - wq->closure = (StgClosure*)evacuate((StgClosure*)wq->closure); - wq->next_queue_entry = (StgTVarWatchQueue *)evacuate((StgClosure*)wq->next_queue_entry); - wq->prev_queue_entry = (StgTVarWatchQueue *)evacuate((StgClosure*)wq->prev_queue_entry); - evac_gen = saved_evac_gen; - failed_to_evac = rtsTrue; // mutable - p += sizeofW(StgTVarWatchQueue); - break; - } - - case TVAR: - { - StgTVar *tvar = ((StgTVar *) p); - evac_gen = 0; - tvar->current_value = evacuate((StgClosure*)tvar->current_value); - tvar->first_watch_queue_entry = (StgTVarWatchQueue *)evacuate((StgClosure*)tvar->first_watch_queue_entry); - evac_gen = saved_evac_gen; - failed_to_evac = rtsTrue; // mutable - p += sizeofW(StgTVar); - break; - } - - case TREC_HEADER: - { - StgTRecHeader *trec = ((StgTRecHeader *) p); - evac_gen = 0; - trec->enclosing_trec = (StgTRecHeader *)evacuate((StgClosure*)trec->enclosing_trec); - trec->current_chunk = (StgTRecChunk *)evacuate((StgClosure*)trec->current_chunk); - trec->invariants_to_check = (StgInvariantCheckQueue *)evacuate((StgClosure*)trec->invariants_to_check); - evac_gen = saved_evac_gen; - failed_to_evac = rtsTrue; // mutable - p += sizeofW(StgTRecHeader); - break; - } - - case TREC_CHUNK: - { - StgWord i; - StgTRecChunk *tc = ((StgTRecChunk *) p); - TRecEntry *e = &(tc -> entries[0]); - evac_gen = 0; - tc->prev_chunk = (StgTRecChunk *)evacuate((StgClosure*)tc->prev_chunk); - for (i = 0; i < tc -> next_entry_idx; i ++, e++ ) { - e->tvar = (StgTVar *)evacuate((StgClosure*)e->tvar); - e->expected_value = evacuate((StgClosure*)e->expected_value); - e->new_value = evacuate((StgClosure*)e->new_value); - } - evac_gen = saved_evac_gen; - failed_to_evac = rtsTrue; // mutable - p += sizeofW(StgTRecChunk); - break; - } - - case ATOMIC_INVARIANT: - { - StgAtomicInvariant *invariant = ((StgAtomicInvariant *) p); - evac_gen = 0; - invariant->code = (StgClosure *)evacuate(invariant->code); - invariant->last_execution = (StgTRecHeader *)evacuate((StgClosure*)invariant->last_execution); - evac_gen = saved_evac_gen; - failed_to_evac = rtsTrue; // mutable - p += sizeofW(StgAtomicInvariant); - break; - } - - case INVARIANT_CHECK_QUEUE: - { - StgInvariantCheckQueue *queue = ((StgInvariantCheckQueue *) p); - evac_gen = 0; - queue->invariant = (StgAtomicInvariant *)evacuate((StgClosure*)queue->invariant); - queue->my_execution = (StgTRecHeader *)evacuate((StgClosure*)queue->my_execution); - queue->next_queue_entry = (StgInvariantCheckQueue *)evacuate((StgClosure*)queue->next_queue_entry); - evac_gen = saved_evac_gen; - failed_to_evac = rtsTrue; // mutable - p += sizeofW(StgInvariantCheckQueue); - break; - } - - default: - barf("scavenge: unimplemented/strange closure type %d @ %p", - info->type, p); - } - - /* - * We need to record the current object on the mutable list if - * (a) It is actually mutable, or - * (b) It contains pointers to a younger generation. - * Case (b) arises if we didn't manage to promote everything that - * the current object points to into the current generation. - */ - if (failed_to_evac) { - failed_to_evac = rtsFalse; - if (stp->gen_no > 0) { - recordMutableGen((StgClosure *)q, stp->gen); - } - } - } - - stp->scan_bd = bd; - stp->scan = p; -} - -/* ----------------------------------------------------------------------------- - Scavenge everything on the mark stack. - - This is slightly different from scavenge(): - - we don't walk linearly through the objects, so the scavenger - doesn't need to advance the pointer on to the next object. - -------------------------------------------------------------------------- */ - -static void -scavenge_mark_stack(void) -{ - StgPtr p, q; - StgInfoTable *info; - nat saved_evac_gen; - - evac_gen = oldest_gen->no; - saved_evac_gen = evac_gen; - -linear_scan: - while (!mark_stack_empty()) { - p = pop_mark_stack(); - - ASSERT(LOOKS_LIKE_CLOSURE_PTR(p)); - info = get_itbl((StgClosure *)p); - - q = p; - switch (info->type) { - - case MVAR: - { - StgMVar *mvar = ((StgMVar *)p); - evac_gen = 0; - mvar->head = (StgTSO *)evacuate((StgClosure *)mvar->head); - mvar->tail = (StgTSO *)evacuate((StgClosure *)mvar->tail); - mvar->value = evacuate((StgClosure *)mvar->value); - evac_gen = saved_evac_gen; - failed_to_evac = rtsTrue; // mutable. - break; - } - - case FUN_2_0: - scavenge_fun_srt(info); - ((StgClosure *)p)->payload[1] = evacuate(((StgClosure *)p)->payload[1]); - ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]); - break; - - case THUNK_2_0: - scavenge_thunk_srt(info); - ((StgThunk *)p)->payload[1] = evacuate(((StgThunk *)p)->payload[1]); - ((StgThunk *)p)->payload[0] = evacuate(((StgThunk *)p)->payload[0]); - break; - - case CONSTR_2_0: - ((StgClosure *)p)->payload[1] = evacuate(((StgClosure *)p)->payload[1]); - ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]); - break; - - case FUN_1_0: - case FUN_1_1: - scavenge_fun_srt(info); - ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]); - break; - - case THUNK_1_0: - case THUNK_1_1: - scavenge_thunk_srt(info); - ((StgThunk *)p)->payload[0] = evacuate(((StgThunk *)p)->payload[0]); - break; - - case CONSTR_1_0: - case CONSTR_1_1: - ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]); - break; - - case FUN_0_1: - case FUN_0_2: - scavenge_fun_srt(info); - break; - - case THUNK_0_1: - case THUNK_0_2: - scavenge_thunk_srt(info); - break; - - case CONSTR_0_1: - case CONSTR_0_2: - break; - - case FUN: - scavenge_fun_srt(info); - goto gen_obj; - - case THUNK: - { - StgPtr end; - - scavenge_thunk_srt(info); - end = (P_)((StgThunk *)p)->payload + info->layout.payload.ptrs; - for (p = (P_)((StgThunk *)p)->payload; p < end; p++) { - *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); - } - break; - } - - gen_obj: - case CONSTR: - case WEAK: - case STABLE_NAME: - { - StgPtr end; - - end = (P_)((StgClosure *)p)->payload + info->layout.payload.ptrs; - for (p = (P_)((StgClosure *)p)->payload; p < end; p++) { - *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); - } - break; - } - - case BCO: { - StgBCO *bco = (StgBCO *)p; - bco->instrs = (StgArrWords *)evacuate((StgClosure *)bco->instrs); - bco->literals = (StgArrWords *)evacuate((StgClosure *)bco->literals); - bco->ptrs = (StgMutArrPtrs *)evacuate((StgClosure *)bco->ptrs); - bco->itbls = (StgArrWords *)evacuate((StgClosure *)bco->itbls); - break; - } - - case IND_PERM: - // don't need to do anything here: the only possible case - // is that we're in a 1-space compacting collector, with - // no "old" generation. - break; - - case IND_OLDGEN: - case IND_OLDGEN_PERM: - ((StgInd *)p)->indirectee = - evacuate(((StgInd *)p)->indirectee); - break; - - case MUT_VAR_CLEAN: - case MUT_VAR_DIRTY: { - rtsBool saved_eager_promotion = eager_promotion; - - eager_promotion = rtsFalse; - ((StgMutVar *)p)->var = evacuate(((StgMutVar *)p)->var); - eager_promotion = saved_eager_promotion; - - if (failed_to_evac) { - ((StgClosure *)q)->header.info = &stg_MUT_VAR_DIRTY_info; - } else { - ((StgClosure *)q)->header.info = &stg_MUT_VAR_CLEAN_info; - } - break; - } - - case CAF_BLACKHOLE: - case SE_CAF_BLACKHOLE: - case SE_BLACKHOLE: - case BLACKHOLE: - case ARR_WORDS: - break; - - case THUNK_SELECTOR: - { - StgSelector *s = (StgSelector *)p; - s->selectee = evacuate(s->selectee); - break; - } - - // A chunk of stack saved in a heap object - case AP_STACK: - { - StgAP_STACK *ap = (StgAP_STACK *)p; - - ap->fun = evacuate(ap->fun); - scavenge_stack((StgPtr)ap->payload, (StgPtr)ap->payload + ap->size); - break; - } - - case PAP: - scavenge_PAP((StgPAP *)p); - break; - - case AP: - scavenge_AP((StgAP *)p); - break; - - case MUT_ARR_PTRS_CLEAN: - case MUT_ARR_PTRS_DIRTY: - // follow everything - { - StgPtr next; - rtsBool saved_eager; - - // We don't eagerly promote objects pointed to by a mutable - // array, but if we find the array only points to objects in - // the same or an older generation, we mark it "clean" and - // avoid traversing it during minor GCs. - saved_eager = eager_promotion; - eager_promotion = rtsFalse; - next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p); - for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) { - *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); - } - eager_promotion = saved_eager; - - if (failed_to_evac) { - ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_DIRTY_info; - } else { - ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_CLEAN_info; - } - - failed_to_evac = rtsTrue; // mutable anyhow. - break; - } - - case MUT_ARR_PTRS_FROZEN: - case MUT_ARR_PTRS_FROZEN0: - // follow everything - { - StgPtr next, q = p; - - next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p); - for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) { - *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); - } - - // If we're going to put this object on the mutable list, then - // set its info ptr to MUT_ARR_PTRS_FROZEN0 to indicate that. - if (failed_to_evac) { - ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_FROZEN0_info; - } else { - ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_FROZEN_info; - } - break; - } - - case TSO: - { - StgTSO *tso = (StgTSO *)p; - rtsBool saved_eager = eager_promotion; - - eager_promotion = rtsFalse; - scavengeTSO(tso); - eager_promotion = saved_eager; - - if (failed_to_evac) { - tso->flags |= TSO_DIRTY; - } else { - tso->flags &= ~TSO_DIRTY; - } - - failed_to_evac = rtsTrue; // always on the mutable list - break; - } - -#if defined(PAR) - case RBH: - { -#if 0 - nat size, ptrs, nonptrs, vhs; - char str[80]; - StgInfoTable *rip = get_closure_info(p, &size, &ptrs, &nonptrs, &vhs, str); -#endif - StgRBH *rbh = (StgRBH *)p; - bh->blocking_queue = - (StgTSO *)evacuate((StgClosure *)bh->blocking_queue); - failed_to_evac = rtsTrue; // mutable anyhow. - debugTrace(DEBUG_gc, "scavenge: RBH %p (%s) (new blocking_queue link=%p)", - p, info_type(p), (StgClosure *)rbh->blocking_queue)); - break; - } - - case BLOCKED_FETCH: - { - StgBlockedFetch *bf = (StgBlockedFetch *)p; - // follow the pointer to the node which is being demanded - (StgClosure *)bf->node = - evacuate((StgClosure *)bf->node); - // follow the link to the rest of the blocking queue - (StgClosure *)bf->link = - evacuate((StgClosure *)bf->link); - debugTrace(DEBUG_gc, "scavenge: %p (%s); node is now %p; exciting, isn't it", - bf, info_type((StgClosure *)bf), - bf->node, info_type(bf->node))); - break; - } - -#ifdef DIST - case REMOTE_REF: -#endif - case FETCH_ME: - break; // nothing to do in this case - - case FETCH_ME_BQ: - { - StgFetchMeBlockingQueue *fmbq = (StgFetchMeBlockingQueue *)p; - (StgClosure *)fmbq->blocking_queue = - evacuate((StgClosure *)fmbq->blocking_queue); - debugTrace(DEBUG_gc, "scavenge: %p (%s) exciting, isn't it", - p, info_type((StgClosure *)p))); - break; - } -#endif /* PAR */ - - case TVAR_WATCH_QUEUE: - { - StgTVarWatchQueue *wq = ((StgTVarWatchQueue *) p); - evac_gen = 0; - wq->closure = (StgClosure*)evacuate((StgClosure*)wq->closure); - wq->next_queue_entry = (StgTVarWatchQueue *)evacuate((StgClosure*)wq->next_queue_entry); - wq->prev_queue_entry = (StgTVarWatchQueue *)evacuate((StgClosure*)wq->prev_queue_entry); - evac_gen = saved_evac_gen; - failed_to_evac = rtsTrue; // mutable - break; - } - - case TVAR: - { - StgTVar *tvar = ((StgTVar *) p); - evac_gen = 0; - tvar->current_value = evacuate((StgClosure*)tvar->current_value); - tvar->first_watch_queue_entry = (StgTVarWatchQueue *)evacuate((StgClosure*)tvar->first_watch_queue_entry); - evac_gen = saved_evac_gen; - failed_to_evac = rtsTrue; // mutable - break; - } - - case TREC_CHUNK: - { - StgWord i; - StgTRecChunk *tc = ((StgTRecChunk *) p); - TRecEntry *e = &(tc -> entries[0]); - evac_gen = 0; - tc->prev_chunk = (StgTRecChunk *)evacuate((StgClosure*)tc->prev_chunk); - for (i = 0; i < tc -> next_entry_idx; i ++, e++ ) { - e->tvar = (StgTVar *)evacuate((StgClosure*)e->tvar); - e->expected_value = evacuate((StgClosure*)e->expected_value); - e->new_value = evacuate((StgClosure*)e->new_value); - } - evac_gen = saved_evac_gen; - failed_to_evac = rtsTrue; // mutable - break; - } - - case TREC_HEADER: - { - StgTRecHeader *trec = ((StgTRecHeader *) p); - evac_gen = 0; - trec->enclosing_trec = (StgTRecHeader *)evacuate((StgClosure*)trec->enclosing_trec); - trec->current_chunk = (StgTRecChunk *)evacuate((StgClosure*)trec->current_chunk); - trec->invariants_to_check = (StgInvariantCheckQueue *)evacuate((StgClosure*)trec->invariants_to_check); - evac_gen = saved_evac_gen; - failed_to_evac = rtsTrue; // mutable - break; - } - - case ATOMIC_INVARIANT: - { - StgAtomicInvariant *invariant = ((StgAtomicInvariant *) p); - evac_gen = 0; - invariant->code = (StgClosure *)evacuate(invariant->code); - invariant->last_execution = (StgTRecHeader *)evacuate((StgClosure*)invariant->last_execution); - evac_gen = saved_evac_gen; - failed_to_evac = rtsTrue; // mutable - break; - } - - case INVARIANT_CHECK_QUEUE: - { - StgInvariantCheckQueue *queue = ((StgInvariantCheckQueue *) p); - evac_gen = 0; - queue->invariant = (StgAtomicInvariant *)evacuate((StgClosure*)queue->invariant); - queue->my_execution = (StgTRecHeader *)evacuate((StgClosure*)queue->my_execution); - queue->next_queue_entry = (StgInvariantCheckQueue *)evacuate((StgClosure*)queue->next_queue_entry); - evac_gen = saved_evac_gen; - failed_to_evac = rtsTrue; // mutable - break; - } - - default: - barf("scavenge_mark_stack: unimplemented/strange closure type %d @ %p", - info->type, p); - } - - if (failed_to_evac) { - failed_to_evac = rtsFalse; - if (evac_gen > 0) { - recordMutableGen((StgClosure *)q, &generations[evac_gen]); - } - } - - // mark the next bit to indicate "scavenged" - mark(q+1, Bdescr(q)); - - } // while (!mark_stack_empty()) - - // start a new linear scan if the mark stack overflowed at some point - if (mark_stack_overflowed && oldgen_scan_bd == NULL) { - debugTrace(DEBUG_gc, "scavenge_mark_stack: starting linear scan"); - mark_stack_overflowed = rtsFalse; - oldgen_scan_bd = oldest_gen->steps[0].old_blocks; - oldgen_scan = oldgen_scan_bd->start; - } - - if (oldgen_scan_bd) { - // push a new thing on the mark stack - loop: - // find a closure that is marked but not scavenged, and start - // from there. - while (oldgen_scan < oldgen_scan_bd->free - && !is_marked(oldgen_scan,oldgen_scan_bd)) { - oldgen_scan++; - } - - if (oldgen_scan < oldgen_scan_bd->free) { - - // already scavenged? - if (is_marked(oldgen_scan+1,oldgen_scan_bd)) { - oldgen_scan += sizeofW(StgHeader) + MIN_PAYLOAD_SIZE; - goto loop; - } - push_mark_stack(oldgen_scan); - // ToDo: bump the linear scan by the actual size of the object - oldgen_scan += sizeofW(StgHeader) + MIN_PAYLOAD_SIZE; - goto linear_scan; - } - - oldgen_scan_bd = oldgen_scan_bd->link; - if (oldgen_scan_bd != NULL) { - oldgen_scan = oldgen_scan_bd->start; - goto loop; - } - } -} - -/* ----------------------------------------------------------------------------- - Scavenge one object. - - This is used for objects that are temporarily marked as mutable - because they contain old-to-new generation pointers. Only certain - objects can have this property. - -------------------------------------------------------------------------- */ - -static rtsBool -scavenge_one(StgPtr p) -{ - const StgInfoTable *info; - nat saved_evac_gen = evac_gen; - rtsBool no_luck; - - ASSERT(LOOKS_LIKE_CLOSURE_PTR(p)); - info = get_itbl((StgClosure *)p); - - switch (info->type) { - - case MVAR: - { - StgMVar *mvar = ((StgMVar *)p); - evac_gen = 0; - mvar->head = (StgTSO *)evacuate((StgClosure *)mvar->head); - mvar->tail = (StgTSO *)evacuate((StgClosure *)mvar->tail); - mvar->value = evacuate((StgClosure *)mvar->value); - evac_gen = saved_evac_gen; - failed_to_evac = rtsTrue; // mutable. - break; - } - - case THUNK: - case THUNK_1_0: - case THUNK_0_1: - case THUNK_1_1: - case THUNK_0_2: - case THUNK_2_0: - { - StgPtr q, end; - - end = (StgPtr)((StgThunk *)p)->payload + info->layout.payload.ptrs; - for (q = (StgPtr)((StgThunk *)p)->payload; q < end; q++) { - *q = (StgWord)(StgPtr)evacuate((StgClosure *)*q); - } - break; - } - - case FUN: - case FUN_1_0: // hardly worth specialising these guys - case FUN_0_1: - case FUN_1_1: - case FUN_0_2: - case FUN_2_0: - case CONSTR: - case CONSTR_1_0: - case CONSTR_0_1: - case CONSTR_1_1: - case CONSTR_0_2: - case CONSTR_2_0: - case WEAK: - case IND_PERM: - { - StgPtr q, end; - - end = (StgPtr)((StgClosure *)p)->payload + info->layout.payload.ptrs; - for (q = (StgPtr)((StgClosure *)p)->payload; q < end; q++) { - *q = (StgWord)(StgPtr)evacuate((StgClosure *)*q); - } - break; - } - - case MUT_VAR_CLEAN: - case MUT_VAR_DIRTY: { - StgPtr q = p; - rtsBool saved_eager_promotion = eager_promotion; - - eager_promotion = rtsFalse; - ((StgMutVar *)p)->var = evacuate(((StgMutVar *)p)->var); - eager_promotion = saved_eager_promotion; - - if (failed_to_evac) { - ((StgClosure *)q)->header.info = &stg_MUT_VAR_DIRTY_info; - } else { - ((StgClosure *)q)->header.info = &stg_MUT_VAR_CLEAN_info; - } - break; - } - - case CAF_BLACKHOLE: - case SE_CAF_BLACKHOLE: - case SE_BLACKHOLE: - case BLACKHOLE: - break; - - case THUNK_SELECTOR: - { - StgSelector *s = (StgSelector *)p; - s->selectee = evacuate(s->selectee); - break; - } - - case AP_STACK: - { - StgAP_STACK *ap = (StgAP_STACK *)p; - - ap->fun = evacuate(ap->fun); - scavenge_stack((StgPtr)ap->payload, (StgPtr)ap->payload + ap->size); - p = (StgPtr)ap->payload + ap->size; - break; - } - - case PAP: - p = scavenge_PAP((StgPAP *)p); - break; - - case AP: - p = scavenge_AP((StgAP *)p); - break; - - case ARR_WORDS: - // nothing to follow - break; - - case MUT_ARR_PTRS_CLEAN: - case MUT_ARR_PTRS_DIRTY: - { - StgPtr next, q; - rtsBool saved_eager; - - // We don't eagerly promote objects pointed to by a mutable - // array, but if we find the array only points to objects in - // the same or an older generation, we mark it "clean" and - // avoid traversing it during minor GCs. - saved_eager = eager_promotion; - eager_promotion = rtsFalse; - q = p; - next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p); - for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) { - *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); - } - eager_promotion = saved_eager; - - if (failed_to_evac) { - ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_DIRTY_info; - } else { - ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_CLEAN_info; - } - - failed_to_evac = rtsTrue; - break; - } - - case MUT_ARR_PTRS_FROZEN: - case MUT_ARR_PTRS_FROZEN0: - { - // follow everything - StgPtr next, q=p; - - next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p); - for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) { - *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); - } - - // If we're going to put this object on the mutable list, then - // set its info ptr to MUT_ARR_PTRS_FROZEN0 to indicate that. - if (failed_to_evac) { - ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_FROZEN0_info; - } else { - ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_FROZEN_info; - } - break; - } - - case TSO: - { - StgTSO *tso = (StgTSO *)p; - rtsBool saved_eager = eager_promotion; - - eager_promotion = rtsFalse; - scavengeTSO(tso); - eager_promotion = saved_eager; - - if (failed_to_evac) { - tso->flags |= TSO_DIRTY; - } else { - tso->flags &= ~TSO_DIRTY; - } - - failed_to_evac = rtsTrue; // always on the mutable list - break; - } - -#if defined(PAR) - case RBH: - { -#if 0 - nat size, ptrs, nonptrs, vhs; - char str[80]; - StgInfoTable *rip = get_closure_info(p, &size, &ptrs, &nonptrs, &vhs, str); -#endif - StgRBH *rbh = (StgRBH *)p; - (StgClosure *)rbh->blocking_queue = - evacuate((StgClosure *)rbh->blocking_queue); - failed_to_evac = rtsTrue; // mutable anyhow. - debugTrace(DEBUG_gc, "scavenge: RBH %p (%s) (new blocking_queue link=%p)", - p, info_type(p), (StgClosure *)rbh->blocking_queue)); - // ToDo: use size of reverted closure here! - break; - } - - case BLOCKED_FETCH: - { - StgBlockedFetch *bf = (StgBlockedFetch *)p; - // follow the pointer to the node which is being demanded - (StgClosure *)bf->node = - evacuate((StgClosure *)bf->node); - // follow the link to the rest of the blocking queue - (StgClosure *)bf->link = - evacuate((StgClosure *)bf->link); - debugTrace(DEBUG_gc, - "scavenge: %p (%s); node is now %p; exciting, isn't it", - bf, info_type((StgClosure *)bf), - bf->node, info_type(bf->node))); - break; - } - -#ifdef DIST - case REMOTE_REF: -#endif - case FETCH_ME: - break; // nothing to do in this case - - case FETCH_ME_BQ: - { - StgFetchMeBlockingQueue *fmbq = (StgFetchMeBlockingQueue *)p; - (StgClosure *)fmbq->blocking_queue = - evacuate((StgClosure *)fmbq->blocking_queue); - debugTrace(DEBUG_gc, "scavenge: %p (%s) exciting, isn't it", - p, info_type((StgClosure *)p))); - break; - } -#endif - - case TVAR_WATCH_QUEUE: - { - StgTVarWatchQueue *wq = ((StgTVarWatchQueue *) p); - evac_gen = 0; - wq->closure = (StgClosure*)evacuate((StgClosure*)wq->closure); - wq->next_queue_entry = (StgTVarWatchQueue *)evacuate((StgClosure*)wq->next_queue_entry); - wq->prev_queue_entry = (StgTVarWatchQueue *)evacuate((StgClosure*)wq->prev_queue_entry); - evac_gen = saved_evac_gen; - failed_to_evac = rtsTrue; // mutable - break; - } - - case TVAR: - { - StgTVar *tvar = ((StgTVar *) p); - evac_gen = 0; - tvar->current_value = evacuate((StgClosure*)tvar->current_value); - tvar->first_watch_queue_entry = (StgTVarWatchQueue *)evacuate((StgClosure*)tvar->first_watch_queue_entry); - evac_gen = saved_evac_gen; - failed_to_evac = rtsTrue; // mutable - break; - } - - case TREC_HEADER: - { - StgTRecHeader *trec = ((StgTRecHeader *) p); - evac_gen = 0; - trec->enclosing_trec = (StgTRecHeader *)evacuate((StgClosure*)trec->enclosing_trec); - trec->current_chunk = (StgTRecChunk *)evacuate((StgClosure*)trec->current_chunk); - trec->invariants_to_check = (StgInvariantCheckQueue *)evacuate((StgClosure*)trec->invariants_to_check); - evac_gen = saved_evac_gen; - failed_to_evac = rtsTrue; // mutable - break; - } - - case TREC_CHUNK: - { - StgWord i; - StgTRecChunk *tc = ((StgTRecChunk *) p); - TRecEntry *e = &(tc -> entries[0]); - evac_gen = 0; - tc->prev_chunk = (StgTRecChunk *)evacuate((StgClosure*)tc->prev_chunk); - for (i = 0; i < tc -> next_entry_idx; i ++, e++ ) { - e->tvar = (StgTVar *)evacuate((StgClosure*)e->tvar); - e->expected_value = evacuate((StgClosure*)e->expected_value); - e->new_value = evacuate((StgClosure*)e->new_value); - } - evac_gen = saved_evac_gen; - failed_to_evac = rtsTrue; // mutable - break; - } - - case ATOMIC_INVARIANT: - { - StgAtomicInvariant *invariant = ((StgAtomicInvariant *) p); - evac_gen = 0; - invariant->code = (StgClosure *)evacuate(invariant->code); - invariant->last_execution = (StgTRecHeader *)evacuate((StgClosure*)invariant->last_execution); - evac_gen = saved_evac_gen; - failed_to_evac = rtsTrue; // mutable - break; - } - - case INVARIANT_CHECK_QUEUE: - { - StgInvariantCheckQueue *queue = ((StgInvariantCheckQueue *) p); - evac_gen = 0; - queue->invariant = (StgAtomicInvariant *)evacuate((StgClosure*)queue->invariant); - queue->my_execution = (StgTRecHeader *)evacuate((StgClosure*)queue->my_execution); - queue->next_queue_entry = (StgInvariantCheckQueue *)evacuate((StgClosure*)queue->next_queue_entry); - evac_gen = saved_evac_gen; - failed_to_evac = rtsTrue; // mutable - break; - } - - case IND_OLDGEN: - case IND_OLDGEN_PERM: - case IND_STATIC: - { - /* Careful here: a THUNK can be on the mutable list because - * it contains pointers to young gen objects. If such a thunk - * is updated, the IND_OLDGEN will be added to the mutable - * list again, and we'll scavenge it twice. evacuate() - * doesn't check whether the object has already been - * evacuated, so we perform that check here. - */ - StgClosure *q = ((StgInd *)p)->indirectee; - if (HEAP_ALLOCED(q) && Bdescr((StgPtr)q)->flags & BF_EVACUATED) { - break; - } - ((StgInd *)p)->indirectee = evacuate(q); - } - -#if 0 && defined(DEBUG) - if (RtsFlags.DebugFlags.gc) - /* Debugging code to print out the size of the thing we just - * promoted - */ - { - StgPtr start = gen->steps[0].scan; - bdescr *start_bd = gen->steps[0].scan_bd; - nat size = 0; - scavenge(&gen->steps[0]); - if (start_bd != gen->steps[0].scan_bd) { - size += (P_)BLOCK_ROUND_UP(start) - start; - start_bd = start_bd->link; - while (start_bd != gen->steps[0].scan_bd) { - size += BLOCK_SIZE_W; - start_bd = start_bd->link; - } - size += gen->steps[0].scan - - (P_)BLOCK_ROUND_DOWN(gen->steps[0].scan); - } else { - size = gen->steps[0].scan - start; - } - debugBelch("evac IND_OLDGEN: %ld bytes", size * sizeof(W_)); - } -#endif - break; - - default: - barf("scavenge_one: strange object %d", (int)(info->type)); - } - - no_luck = failed_to_evac; - failed_to_evac = rtsFalse; - return (no_luck); -} - -/* ----------------------------------------------------------------------------- - Scavenging mutable lists. - - We treat the mutable list of each generation > N (i.e. all the - generations older than the one being collected) as roots. We also - remove non-mutable objects from the mutable list at this point. - -------------------------------------------------------------------------- */ - -static void -scavenge_mutable_list(generation *gen) -{ - bdescr *bd; - StgPtr p, q; - - bd = gen->saved_mut_list; - - evac_gen = gen->no; - for (; bd != NULL; bd = bd->link) { - for (q = bd->start; q < bd->free; q++) { - p = (StgPtr)*q; - ASSERT(LOOKS_LIKE_CLOSURE_PTR(p)); - -#ifdef DEBUG - switch (get_itbl((StgClosure *)p)->type) { - case MUT_VAR_CLEAN: - barf("MUT_VAR_CLEAN on mutable list"); - case MUT_VAR_DIRTY: - mutlist_MUTVARS++; break; - case MUT_ARR_PTRS_CLEAN: - case MUT_ARR_PTRS_DIRTY: - case MUT_ARR_PTRS_FROZEN: - case MUT_ARR_PTRS_FROZEN0: - mutlist_MUTARRS++; break; - default: - mutlist_OTHERS++; break; - } -#endif - - // Check whether this object is "clean", that is it - // definitely doesn't point into a young generation. - // Clean objects don't need to be scavenged. Some clean - // objects (MUT_VAR_CLEAN) are not kept on the mutable - // list at all; others, such as MUT_ARR_PTRS_CLEAN and - // TSO, are always on the mutable list. - // - switch (get_itbl((StgClosure *)p)->type) { - case MUT_ARR_PTRS_CLEAN: - recordMutableGen((StgClosure *)p,gen); - continue; - case TSO: { - StgTSO *tso = (StgTSO *)p; - if ((tso->flags & TSO_DIRTY) == 0) { - // A clean TSO: we don't have to traverse its - // stack. However, we *do* follow the link field: - // we don't want to have to mark a TSO dirty just - // because we put it on a different queue. - if (tso->why_blocked != BlockedOnBlackHole) { - tso->link = (StgTSO *)evacuate((StgClosure *)tso->link); - } - recordMutableGen((StgClosure *)p,gen); - continue; - } - } - default: - ; - } - - if (scavenge_one(p)) { - // didn't manage to promote everything, so put the - // object back on the list. - recordMutableGen((StgClosure *)p,gen); - } - } - } - - // free the old mut_list - freeChain(gen->saved_mut_list); - gen->saved_mut_list = NULL; -} - - -static void -scavenge_static(void) -{ - StgClosure* p = static_objects; - const StgInfoTable *info; - - /* Always evacuate straight to the oldest generation for static - * objects */ - evac_gen = oldest_gen->no; - - /* keep going until we've scavenged all the objects on the linked - list... */ - while (p != END_OF_STATIC_LIST) { - - ASSERT(LOOKS_LIKE_CLOSURE_PTR(p)); - info = get_itbl(p); - /* - if (info->type==RBH) - info = REVERT_INFOPTR(info); // if it's an RBH, look at the orig closure - */ - // make sure the info pointer is into text space - - /* Take this object *off* the static_objects list, - * and put it on the scavenged_static_objects list. - */ - static_objects = *STATIC_LINK(info,p); - *STATIC_LINK(info,p) = scavenged_static_objects; - scavenged_static_objects = p; - - switch (info -> type) { - - case IND_STATIC: - { - StgInd *ind = (StgInd *)p; - ind->indirectee = evacuate(ind->indirectee); - - /* might fail to evacuate it, in which case we have to pop it - * back on the mutable list of the oldest generation. We - * leave it *on* the scavenged_static_objects list, though, - * in case we visit this object again. - */ - if (failed_to_evac) { - failed_to_evac = rtsFalse; - recordMutableGen((StgClosure *)p,oldest_gen); - } - break; - } - - case THUNK_STATIC: - scavenge_thunk_srt(info); - break; - - case FUN_STATIC: - scavenge_fun_srt(info); - break; - - case CONSTR_STATIC: - { - StgPtr q, next; - - next = (P_)p->payload + info->layout.payload.ptrs; - // evacuate the pointers - for (q = (P_)p->payload; q < next; q++) { - *q = (StgWord)(StgPtr)evacuate((StgClosure *)*q); - } - break; - } - - default: - barf("scavenge_static: strange closure %d", (int)(info->type)); - } - - ASSERT(failed_to_evac == rtsFalse); - - /* get the next static object from the list. Remember, there might - * be more stuff on this list now that we've done some evacuating! - * (static_objects is a global) - */ - p = static_objects; - } -} - -/* ----------------------------------------------------------------------------- - scavenge a chunk of memory described by a bitmap - -------------------------------------------------------------------------- */ - -static void -scavenge_large_bitmap( StgPtr p, StgLargeBitmap *large_bitmap, nat size ) -{ - nat i, b; - StgWord bitmap; - - b = 0; - bitmap = large_bitmap->bitmap[b]; - for (i = 0; i < size; ) { - if ((bitmap & 1) == 0) { - *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); - } - i++; - p++; - if (i % BITS_IN(W_) == 0) { - b++; - bitmap = large_bitmap->bitmap[b]; - } else { - bitmap = bitmap >> 1; - } - } -} - -STATIC_INLINE StgPtr -scavenge_small_bitmap (StgPtr p, nat size, StgWord bitmap) -{ - while (size > 0) { - if ((bitmap & 1) == 0) { - *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); - } - p++; - bitmap = bitmap >> 1; - size--; - } - return p; -} - -/* ----------------------------------------------------------------------------- - scavenge_stack walks over a section of stack and evacuates all the - objects pointed to by it. We can use the same code for walking - AP_STACK_UPDs, since these are just sections of copied stack. - -------------------------------------------------------------------------- */ - - -static void -scavenge_stack(StgPtr p, StgPtr stack_end) -{ - const StgRetInfoTable* info; - StgWord bitmap; - nat size; - - /* - * Each time around this loop, we are looking at a chunk of stack - * that starts with an activation record. - */ - - while (p < stack_end) { - info = get_ret_itbl((StgClosure *)p); - - switch (info->i.type) { - - case UPDATE_FRAME: - // In SMP, we can get update frames that point to indirections - // when two threads evaluate the same thunk. We do attempt to - // discover this situation in threadPaused(), but it's - // possible that the following sequence occurs: - // - // A B - // enter T - // enter T - // blackhole T - // update T - // GC - // - // Now T is an indirection, and the update frame is already - // marked on A's stack, so we won't traverse it again in - // threadPaused(). We could traverse the whole stack again - // before GC, but that seems like overkill. - // - // Scavenging this update frame as normal would be disastrous; - // the updatee would end up pointing to the value. So we turn - // the indirection into an IND_PERM, so that evacuate will - // copy the indirection into the old generation instead of - // discarding it. - if (get_itbl(((StgUpdateFrame *)p)->updatee)->type == IND) { - ((StgUpdateFrame *)p)->updatee->header.info = - (StgInfoTable *)&stg_IND_PERM_info; - } - ((StgUpdateFrame *)p)->updatee - = evacuate(((StgUpdateFrame *)p)->updatee); - p += sizeofW(StgUpdateFrame); - continue; - - // small bitmap (< 32 entries, or 64 on a 64-bit machine) - case CATCH_STM_FRAME: - case CATCH_RETRY_FRAME: - case ATOMICALLY_FRAME: - case STOP_FRAME: - case CATCH_FRAME: - case RET_SMALL: - case RET_VEC_SMALL: - bitmap = BITMAP_BITS(info->i.layout.bitmap); - size = BITMAP_SIZE(info->i.layout.bitmap); - // NOTE: the payload starts immediately after the info-ptr, we - // don't have an StgHeader in the same sense as a heap closure. - p++; - p = scavenge_small_bitmap(p, size, bitmap); - - follow_srt: - if (major_gc) - scavenge_srt((StgClosure **)GET_SRT(info), info->i.srt_bitmap); - continue; - - case RET_BCO: { - StgBCO *bco; - nat size; - - p++; - *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); - bco = (StgBCO *)*p; - p++; - size = BCO_BITMAP_SIZE(bco); - scavenge_large_bitmap(p, BCO_BITMAP(bco), size); - p += size; - continue; - } - - // large bitmap (> 32 entries, or > 64 on a 64-bit machine) - case RET_BIG: - case RET_VEC_BIG: - { - nat size; - - size = GET_LARGE_BITMAP(&info->i)->size; - p++; - scavenge_large_bitmap(p, GET_LARGE_BITMAP(&info->i), size); - p += size; - // and don't forget to follow the SRT - goto follow_srt; - } - - // Dynamic bitmap: the mask is stored on the stack, and - // there are a number of non-pointers followed by a number - // of pointers above the bitmapped area. (see StgMacros.h, - // HEAP_CHK_GEN). - case RET_DYN: - { - StgWord dyn; - dyn = ((StgRetDyn *)p)->liveness; - - // traverse the bitmap first - bitmap = RET_DYN_LIVENESS(dyn); - p = (P_)&((StgRetDyn *)p)->payload[0]; - size = RET_DYN_BITMAP_SIZE; - p = scavenge_small_bitmap(p, size, bitmap); - - // skip over the non-ptr words - p += RET_DYN_NONPTRS(dyn) + RET_DYN_NONPTR_REGS_SIZE; - - // follow the ptr words - for (size = RET_DYN_PTRS(dyn); size > 0; size--) { - *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); - p++; - } - continue; - } - - case RET_FUN: - { - StgRetFun *ret_fun = (StgRetFun *)p; - StgFunInfoTable *fun_info; - - ret_fun->fun = evacuate(ret_fun->fun); - fun_info = get_fun_itbl(ret_fun->fun); - p = scavenge_arg_block(fun_info, ret_fun->payload); - goto follow_srt; - } - - default: - barf("scavenge_stack: weird activation record found on stack: %d", (int)(info->i.type)); - } - } -} - -/*----------------------------------------------------------------------------- - scavenge the large object list. - - evac_gen set by caller; similar games played with evac_gen as with - scavenge() - see comment at the top of scavenge(). Most large - objects are (repeatedly) mutable, so most of the time evac_gen will - be zero. - --------------------------------------------------------------------------- */ - -static void -scavenge_large(step *stp) -{ - bdescr *bd; - StgPtr p; - - bd = stp->new_large_objects; - - for (; bd != NULL; bd = stp->new_large_objects) { - - /* take this object *off* the large objects list and put it on - * the scavenged large objects list. This is so that we can - * treat new_large_objects as a stack and push new objects on - * the front when evacuating. - */ - stp->new_large_objects = bd->link; - dbl_link_onto(bd, &stp->scavenged_large_objects); - - // update the block count in this step. - stp->n_scavenged_large_blocks += bd->blocks; - - p = bd->start; - if (scavenge_one(p)) { - if (stp->gen_no > 0) { - recordMutableGen((StgClosure *)p, stp->gen); - } - } - } -} - -/* ----------------------------------------------------------------------------- - Initialising the static object & mutable lists - -------------------------------------------------------------------------- */ - -static void -zero_static_object_list(StgClosure* first_static) -{ - StgClosure* p; - StgClosure* link; - const StgInfoTable *info; - - for (p = first_static; p != END_OF_STATIC_LIST; p = link) { - info = get_itbl(p); - link = *STATIC_LINK(info, p); - *STATIC_LINK(info,p) = NULL; - } -} - -/* ----------------------------------------------------------------------------- - Reverting CAFs - -------------------------------------------------------------------------- */ - -void -revertCAFs( void ) -{ - StgIndStatic *c; - - for (c = (StgIndStatic *)revertible_caf_list; c != NULL; - c = (StgIndStatic *)c->static_link) - { - SET_INFO(c, c->saved_info); - c->saved_info = NULL; - // could, but not necessary: c->static_link = NULL; - } - revertible_caf_list = NULL; -} - -void -markCAFs( evac_fn evac ) -{ - StgIndStatic *c; - - for (c = (StgIndStatic *)caf_list; c != NULL; - c = (StgIndStatic *)c->static_link) - { - evac(&c->indirectee); - } - for (c = (StgIndStatic *)revertible_caf_list; c != NULL; - c = (StgIndStatic *)c->static_link) - { - evac(&c->indirectee); - } -} - -/* ----------------------------------------------------------------------------- - Sanity code for CAF garbage collection. - - With DEBUG turned on, we manage a CAF list in addition to the SRT - mechanism. After GC, we run down the CAF list and blackhole any - CAFs which have been garbage collected. This means we get an error - whenever the program tries to enter a garbage collected CAF. - - Any garbage collected CAFs are taken off the CAF list at the same - time. - -------------------------------------------------------------------------- */ - -#if 0 && defined(DEBUG) - -static void -gcCAFs(void) -{ - StgClosure* p; - StgClosure** pp; - const StgInfoTable *info; - nat i; - - i = 0; - p = caf_list; - pp = &caf_list; - - while (p != NULL) { - - info = get_itbl(p); - - ASSERT(info->type == IND_STATIC); - - if (STATIC_LINK(info,p) == NULL) { - debugTrace(DEBUG_gccafs, "CAF gc'd at 0x%04lx", (long)p); - // black hole it - SET_INFO(p,&stg_BLACKHOLE_info); - p = STATIC_LINK2(info,p); - *pp = p; - } - else { - pp = &STATIC_LINK2(info,p); - p = *pp; - i++; - } - - } - - debugTrace(DEBUG_gccafs, "%d CAFs live", i); -} -#endif - - -/* ----------------------------------------------------------------------------- - * Stack squeezing - * - * Code largely pinched from old RTS, then hacked to bits. We also do - * lazy black holing here. - * - * -------------------------------------------------------------------------- */ - -struct stack_gap { StgWord gap_size; struct stack_gap *next_gap; }; - -static void -stackSqueeze(StgTSO *tso, StgPtr bottom) -{ - StgPtr frame; - rtsBool prev_was_update_frame; - StgClosure *updatee = NULL; - StgRetInfoTable *info; - StgWord current_gap_size; - struct stack_gap *gap; - - // Stage 1: - // Traverse the stack upwards, replacing adjacent update frames - // with a single update frame and a "stack gap". A stack gap - // contains two values: the size of the gap, and the distance - // to the next gap (or the stack top). - - frame = tso->sp; - - ASSERT(frame < bottom); - - prev_was_update_frame = rtsFalse; - current_gap_size = 0; - gap = (struct stack_gap *) (tso->sp - sizeofW(StgUpdateFrame)); - - while (frame < bottom) { - - info = get_ret_itbl((StgClosure *)frame); - switch (info->i.type) { - - case UPDATE_FRAME: - { - StgUpdateFrame *upd = (StgUpdateFrame *)frame; - - if (prev_was_update_frame) { - - TICK_UPD_SQUEEZED(); - /* wasn't there something about update squeezing and ticky to be - * sorted out? oh yes: we aren't counting each enter properly - * in this case. See the log somewhere. KSW 1999-04-21 - * - * Check two things: that the two update frames don't point to - * the same object, and that the updatee_bypass isn't already an - * indirection. Both of these cases only happen when we're in a - * block hole-style loop (and there are multiple update frames - * on the stack pointing to the same closure), but they can both - * screw us up if we don't check. - */ - if (upd->updatee != updatee && !closure_IND(upd->updatee)) { - UPD_IND_NOLOCK(upd->updatee, updatee); - } - - // now mark this update frame as a stack gap. The gap - // marker resides in the bottom-most update frame of - // the series of adjacent frames, and covers all the - // frames in this series. - current_gap_size += sizeofW(StgUpdateFrame); - ((struct stack_gap *)frame)->gap_size = current_gap_size; - ((struct stack_gap *)frame)->next_gap = gap; - - frame += sizeofW(StgUpdateFrame); - continue; - } - - // single update frame, or the topmost update frame in a series - else { - prev_was_update_frame = rtsTrue; - updatee = upd->updatee; - frame += sizeofW(StgUpdateFrame); - continue; - } - } - - default: - prev_was_update_frame = rtsFalse; - - // we're not in a gap... check whether this is the end of a gap - // (an update frame can't be the end of a gap). - if (current_gap_size != 0) { - gap = (struct stack_gap *) (frame - sizeofW(StgUpdateFrame)); - } - current_gap_size = 0; - - frame += stack_frame_sizeW((StgClosure *)frame); - continue; - } - } - - if (current_gap_size != 0) { - gap = (struct stack_gap *) (frame - sizeofW(StgUpdateFrame)); - } - - // Now we have a stack with gaps in it, and we have to walk down - // shoving the stack up to fill in the gaps. A diagram might - // help: - // - // +| ********* | - // | ********* | <- sp - // | | - // | | <- gap_start - // | ......... | | - // | stack_gap | <- gap | chunk_size - // | ......... | | - // | ......... | <- gap_end v - // | ********* | - // | ********* | - // | ********* | - // -| ********* | - // - // 'sp' points the the current top-of-stack - // 'gap' points to the stack_gap structure inside the gap - // ***** indicates real stack data - // ..... indicates gap - // <empty> indicates unused - // - { - void *sp; - void *gap_start, *next_gap_start, *gap_end; - nat chunk_size; - - next_gap_start = (void *)((unsigned char*)gap + sizeof(StgUpdateFrame)); - sp = next_gap_start; - - while ((StgPtr)gap > tso->sp) { - - // we're working in *bytes* now... - gap_start = next_gap_start; - gap_end = (void*) ((unsigned char*)gap_start - gap->gap_size * sizeof(W_)); - - gap = gap->next_gap; - next_gap_start = (void *)((unsigned char*)gap + sizeof(StgUpdateFrame)); - - chunk_size = (unsigned char*)gap_end - (unsigned char*)next_gap_start; - sp -= chunk_size; - memmove(sp, next_gap_start, chunk_size); - } - - tso->sp = (StgPtr)sp; - } -} - -/* ----------------------------------------------------------------------------- - * Pausing a thread - * - * We have to prepare for GC - this means doing lazy black holing - * here. We also take the opportunity to do stack squeezing if it's - * turned on. - * -------------------------------------------------------------------------- */ -void -threadPaused(Capability *cap, StgTSO *tso) -{ - StgClosure *frame; - StgRetInfoTable *info; - StgClosure *bh; - StgPtr stack_end; - nat words_to_squeeze = 0; - nat weight = 0; - nat weight_pending = 0; - rtsBool prev_was_update_frame; - - // Check to see whether we have threads waiting to raise - // exceptions, and we're not blocking exceptions, or are blocked - // interruptibly. This is important; if a thread is running with - // TSO_BLOCKEX and becomes blocked interruptibly, this is the only - // place we ensure that the blocked_exceptions get a chance. - maybePerformBlockedException (cap, tso); - if (tso->what_next == ThreadKilled) { return; } - - stack_end = &tso->stack[tso->stack_size]; - - frame = (StgClosure *)tso->sp; - - while (1) { - // If we've already marked this frame, then stop here. - if (frame->header.info == (StgInfoTable *)&stg_marked_upd_frame_info) { - goto end; - } - - info = get_ret_itbl(frame); - - switch (info->i.type) { - - case UPDATE_FRAME: - - SET_INFO(frame, (StgInfoTable *)&stg_marked_upd_frame_info); - - bh = ((StgUpdateFrame *)frame)->updatee; - - if (closure_IND(bh) || bh->header.info == &stg_BLACKHOLE_info) { - debugTrace(DEBUG_squeeze, - "suspending duplicate work: %ld words of stack", - (long)((StgPtr)frame - tso->sp)); - - // If this closure is already an indirection, then - // suspend the computation up to this point: - suspendComputation(cap,tso,(StgPtr)frame); - - // Now drop the update frame, and arrange to return - // the value to the frame underneath: - tso->sp = (StgPtr)frame + sizeofW(StgUpdateFrame) - 2; - tso->sp[1] = (StgWord)bh; - tso->sp[0] = (W_)&stg_enter_info; - - // And continue with threadPaused; there might be - // yet more computation to suspend. - threadPaused(cap,tso); - return; - } - - if (bh->header.info != &stg_CAF_BLACKHOLE_info) { -#if (!defined(LAZY_BLACKHOLING)) && defined(DEBUG) - debugBelch("Unexpected lazy BHing required at 0x%04lx\n",(long)bh); -#endif - // zero out the slop so that the sanity checker can tell - // where the next closure is. - DEBUG_FILL_SLOP(bh); -#ifdef PROFILING - // @LDV profiling - // We pretend that bh is now dead. - LDV_recordDead_FILL_SLOP_DYNAMIC((StgClosure *)bh); -#endif - SET_INFO(bh,&stg_BLACKHOLE_info); - - // We pretend that bh has just been created. - LDV_RECORD_CREATE(bh); - } - - frame = (StgClosure *) ((StgUpdateFrame *)frame + 1); - if (prev_was_update_frame) { - words_to_squeeze += sizeofW(StgUpdateFrame); - weight += weight_pending; - weight_pending = 0; - } - prev_was_update_frame = rtsTrue; - break; - - case STOP_FRAME: - goto end; - - // normal stack frames; do nothing except advance the pointer - default: - { - nat frame_size = stack_frame_sizeW(frame); - weight_pending += frame_size; - frame = (StgClosure *)((StgPtr)frame + frame_size); - prev_was_update_frame = rtsFalse; - } - } - } - -end: - debugTrace(DEBUG_squeeze, - "words_to_squeeze: %d, weight: %d, squeeze: %s", - words_to_squeeze, weight, - weight < words_to_squeeze ? "YES" : "NO"); - - // Should we squeeze or not? Arbitrary heuristic: we squeeze if - // the number of words we have to shift down is less than the - // number of stack words we squeeze away by doing so. - if (RtsFlags.GcFlags.squeezeUpdFrames == rtsTrue && - weight < words_to_squeeze) { - stackSqueeze(tso, (StgPtr)frame); - } -} - -/* ----------------------------------------------------------------------------- - * Debugging - * -------------------------------------------------------------------------- */ - -#if DEBUG -void -printMutableList(generation *gen) -{ - bdescr *bd; - StgPtr p; - - debugBelch("mutable list %p: ", gen->mut_list); - - for (bd = gen->mut_list; bd != NULL; bd = bd->link) { - for (p = bd->start; p < bd->free; p++) { - debugBelch("%p (%s), ", (void *)*p, info_type((StgClosure *)*p)); - } - } - debugBelch("\n"); -} -#endif /* DEBUG */ |