X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Frts%2FGC.c;h=a13cd33afadd346ed79e20ac72235ea4e62887eb;hb=a1b4e3b88a6987deed7bb7f1bd870b30eef1b475;hp=8dbe589c1043ab9d52de6005c86ec22ea545675e;hpb=a24b09c73594fd757a749ba2ce8338162a2d70b6;p=ghc-hetmet.git diff --git a/ghc/rts/GC.c b/ghc/rts/GC.c index 8dbe589..a13cd33 100644 --- a/ghc/rts/GC.c +++ b/ghc/rts/GC.c @@ -1,7 +1,6 @@ /* ----------------------------------------------------------------------------- - * $Id: GC.c,v 1.133 2002/04/13 05:16:25 sof Exp $ * - * (c) The GHC Team 1998-1999 + * (c) The GHC Team 1998-2003 * * Generational garbage collector * @@ -11,22 +10,24 @@ #include "Rts.h" #include "RtsFlags.h" #include "RtsUtils.h" +#include "Apply.h" +#include "OSThreads.h" #include "Storage.h" -#include "StoragePriv.h" +#include "LdvProfile.h" +#include "Updates.h" #include "Stats.h" #include "Schedule.h" -#include "SchedAPI.h" // for ReverCAFs prototype #include "Sanity.h" #include "BlockAlloc.h" #include "MBlock.h" -#include "Main.h" #include "ProfHeap.h" #include "SchedAPI.h" #include "Weak.h" -#include "StablePriv.h" #include "Prelude.h" #include "ParTicky.h" // ToDo: move into Rts.h #include "GCCompact.h" +#include "RtsSignals.h" +#include "STM.h" #if defined(GRAN) || defined(PAR) # include "GranSimRts.h" # include "ParallelRts.h" @@ -43,7 +44,14 @@ #endif #include "RetainerProfile.h" -#include "LdvProfile.h" + +#include + +// Turn off inlining when debugging - it obfuscates things +#ifdef DEBUG +# undef STATIC_INLINE +# define STATIC_INLINE static +#endif /* STATIC OBJECT LIST. * @@ -79,8 +87,8 @@ * We build up a static object list while collecting generations 0..N, * which is then appended to the static object list of generation N+1. */ -StgClosure* static_objects; // live static objects -StgClosure* scavenged_static_objects; // static objects scavenged so far +static StgClosure* static_objects; // live static objects +StgClosure* scavenged_static_objects; // static objects scavenged so far /* N is the oldest generation being collected, where the generations * are numbered starting at 0. A major GC (indicated by the major_gc @@ -96,6 +104,10 @@ static rtsBool major_gc; */ static nat evac_gen; +/* Whether to do eager promotion or not. + */ +static rtsBool eager_promotion; + /* Weak pointers */ StgWeak *old_weak_ptr_list; // also pending finaliser list @@ -116,40 +128,65 @@ StgTSO *resurrected_threads; */ static rtsBool failed_to_evac; -/* Old to-space (used for two-space collector only) +/* Saved nursery (used for 2-space collector only) */ -bdescr *old_to_blocks; - +static bdescr *saved_nursery; +static nat saved_n_blocks; + /* Data used for allocation area sizing. */ -lnat new_blocks; // blocks allocated during this GC -lnat g0s0_pcnt_kept = 30; // percentage of g0s0 live at last minor GC +static lnat new_blocks; // blocks allocated during this GC +static lnat new_scavd_blocks; // ditto, but depth-first blocks +static lnat g0s0_pcnt_kept = 30; // percentage of g0s0 live at last minor GC /* Used to avoid long recursion due to selector thunks */ -lnat thunk_selector_depth = 0; -#define MAX_THUNK_SELECTOR_DEPTH 256 +static lnat thunk_selector_depth = 0; +#define MAX_THUNK_SELECTOR_DEPTH 8 + +/* Mut-list stats */ +#ifdef DEBUG +static nat + mutlist_MUTVARS, + mutlist_MUTARRS, + mutlist_OTHERS; +#endif /* ----------------------------------------------------------------------------- Static function declarations -------------------------------------------------------------------------- */ +static bdescr * gc_alloc_block ( step *stp ); static void mark_root ( StgClosure **root ); -static StgClosure * evacuate ( StgClosure *q ); + +// Use a register argument for evacuate, if available. +#if __GNUC__ >= 2 +#define REGPARM1 __attribute__((regparm(1))) +#else +#define REGPARM1 +#endif + +REGPARM1 static StgClosure * evacuate (StgClosure *q); + static void zero_static_object_list ( StgClosure* first_static ); -static void zero_mutable_list ( StgMutClosure *first ); static rtsBool traverse_weak_ptr_list ( void ); static void mark_weak_ptr_list ( StgWeak **list ); -static void scavenge ( step * ); -static void scavenge_mark_stack ( void ); -static void scavenge_stack ( StgPtr p, StgPtr stack_end ); -static rtsBool scavenge_one ( StgPtr p ); -static void scavenge_large ( step * ); -static void scavenge_static ( void ); -static void scavenge_mutable_list ( generation *g ); -static void scavenge_mut_once_list ( generation *g ); +static StgClosure * eval_thunk_selector ( nat field, StgSelector * p ); + + +static void scavenge ( step * ); +static void scavenge_mark_stack ( void ); +static void scavenge_stack ( StgPtr p, StgPtr stack_end ); +static rtsBool scavenge_one ( StgPtr p ); +static void scavenge_large ( step * ); +static void scavenge_static ( void ); +static void scavenge_mutable_list ( generation *g ); + +static void scavenge_large_bitmap ( StgPtr p, + StgLargeBitmap *large_bitmap, + nat size ); #if 0 && defined(DEBUG) static void gcCAFs ( void ); @@ -172,58 +209,133 @@ static rtsBool mark_stack_overflowed; static bdescr *oldgen_scan_bd; static StgPtr oldgen_scan; -static inline rtsBool +STATIC_INLINE rtsBool mark_stack_empty(void) { return mark_sp == mark_stack; } -static inline rtsBool +STATIC_INLINE rtsBool mark_stack_full(void) { return mark_sp >= mark_splim; } -static inline void +STATIC_INLINE void reset_mark_stack(void) { mark_sp = mark_stack; } -static inline void +STATIC_INLINE void push_mark_stack(StgPtr p) { *mark_sp++ = p; } -static inline StgPtr +STATIC_INLINE StgPtr pop_mark_stack(void) { return *--mark_sp; } /* ----------------------------------------------------------------------------- + Allocate a new to-space block in the given step. + -------------------------------------------------------------------------- */ + +static bdescr * +gc_alloc_block(step *stp) +{ + bdescr *bd = allocBlock(); + bd->gen_no = stp->gen_no; + bd->step = stp; + bd->link = NULL; + + // blocks in to-space in generations up to and including N + // get the BF_EVACUATED flag. + if (stp->gen_no <= N) { + bd->flags = BF_EVACUATED; + } else { + bd->flags = 0; + } + + // Start a new to-space block, chain it on after the previous one. + if (stp->hp_bd != NULL) { + stp->hp_bd->free = stp->hp; + stp->hp_bd->link = bd; + } + + stp->hp_bd = bd; + stp->hp = bd->start; + stp->hpLim = stp->hp + BLOCK_SIZE_W; + + stp->n_blocks++; + new_blocks++; + + return bd; +} + +static bdescr * +gc_alloc_scavd_block(step *stp) +{ + bdescr *bd = allocBlock(); + bd->gen_no = stp->gen_no; + bd->step = stp; + + // blocks in to-space in generations up to and including N + // get the BF_EVACUATED flag. + if (stp->gen_no <= N) { + bd->flags = BF_EVACUATED; + } else { + bd->flags = 0; + } + + bd->link = stp->blocks; + stp->blocks = bd; + + if (stp->scavd_hp != NULL) { + Bdescr(stp->scavd_hp)->free = stp->scavd_hp; + } + stp->scavd_hp = bd->start; + stp->scavd_hpLim = stp->scavd_hp + BLOCK_SIZE_W; + + stp->n_blocks++; + new_scavd_blocks++; + + return bd; +} + +/* ----------------------------------------------------------------------------- GarbageCollect - For garbage collecting generation N (and all younger generations): + Rough outline of the algorithm: for garbage collecting generation N + (and all younger generations): - follow all pointers in the root set. the root set includes all - mutable objects in all steps in all generations. + mutable objects in all generations (mutable_list). - for each pointer, evacuate the object it points to into either - + to-space in the next higher step in that generation, if one exists, - + if the object's generation == N, then evacuate it to the next - generation if one exists, or else to-space in the current - generation. - + if the object's generation < N, then evacuate it to to-space - in the next generation. + + + to-space of the step given by step->to, which is the next + highest step in this generation or the first step in the next + generation if this is the last step. + + + to-space of generations[evac_gen]->steps[0], if evac_gen != 0. + When we evacuate an object we attempt to evacuate + everything it points to into the same generation - this is + achieved by setting evac_gen to the desired generation. If + we can't do this, then an entry in the mut list has to + be made for the cross-generation pointer. + + + if the object is already in a generation > N, then leave + it alone. - repeatedly scavenge to-space from each step in each generation being collected until no more objects can be evacuated. - free from-space in each step, and set from-space = to-space. - Locks held: sched_mutex + Locks held: all capabilities are held throughout GarbageCollect(). -------------------------------------------------------------------------- */ @@ -232,22 +344,43 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) { bdescr *bd; step *stp; - lnat live, allocated, collected = 0, copied = 0; + lnat live, allocated, copied = 0, scavd_copied = 0; lnat oldgen_saved_blocks = 0; - nat g, s; + nat g, s, i; + + ACQUIRE_SM_LOCK; #ifdef PROFILING CostCentreStack *prev_CCS; #endif #if defined(DEBUG) && defined(GRAN) - IF_DEBUG(gc, belch("@@ Starting garbage collection at %ld (%lx)\n", + IF_DEBUG(gc, debugBelch("@@ Starting garbage collection at %ld (%lx)\n", Now, Now)); #endif +#if defined(RTS_USER_SIGNALS) + // block signals + blockUserSignals(); +#endif + + // tell the STM to discard any cached closures its hoping to re-use + stmPreGCHook(); + // tell the stats department that we've started a GC stat_startGC(); +#ifdef DEBUG + // check for memory leaks if DEBUG is on + memInventory(); +#endif + +#ifdef DEBUG + mutlist_MUTVARS = 0; + mutlist_MUTARRS = 0; + mutlist_OTHERS = 0; +#endif + // Init stats and print par specific (timing) info PAR_TICKY_PAR_START(); @@ -296,31 +429,39 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) static_objects = END_OF_STATIC_LIST; scavenged_static_objects = END_OF_STATIC_LIST; - /* zero the mutable list for the oldest generation (see comment by - * zero_mutable_list below). - */ - if (major_gc) { - zero_mutable_list(generations[RtsFlags.GcFlags.generations-1].mut_once_list); - } - - /* Save the old to-space if we're doing a two-space collection + /* Save the nursery if we're doing a two-space collection. + * g0s0->blocks will be used for to-space, so we need to get the + * nursery out of the way. */ if (RtsFlags.GcFlags.generations == 1) { - old_to_blocks = g0s0->to_blocks; - g0s0->to_blocks = NULL; + saved_nursery = g0s0->blocks; + saved_n_blocks = g0s0->n_blocks; + g0s0->blocks = NULL; + g0s0->n_blocks = 0; } /* Keep a count of how many new blocks we allocated during this GC * (used for resizing the allocation area, later). */ new_blocks = 0; + new_scavd_blocks = 0; - /* Initialise to-space in all the generations/steps that we're - * collecting. - */ + // Initialise to-space in all the generations/steps that we're + // collecting. + // for (g = 0; g <= N; g++) { - generations[g].mut_once_list = END_MUT_LIST; - generations[g].mut_list = END_MUT_LIST; + + // throw away the mutable list. Invariant: the mutable list + // always has at least one block; this means we can avoid a check for + // NULL in recordMutable(). + if (g != 0) { + freeChain(generations[g].mut_list); + generations[g].mut_list = allocBlock(); + for (i = 0; i < n_capabilities; i++) { + freeChain(capabilities[i].mut_lists[g]); + capabilities[i].mut_lists[g] = allocBlock(); + } + } for (s = 0; s < generations[g].n_steps; s++) { @@ -329,31 +470,35 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) continue; } - /* Get a free block for to-space. Extra blocks will be chained on - * as necessary. - */ - bd = allocBlock(); stp = &generations[g].steps[s]; ASSERT(stp->gen_no == g); - ASSERT(stp->hp ? Bdescr(stp->hp)->step == stp : rtsTrue); - bd->gen_no = g; - bd->step = stp; - bd->link = NULL; - bd->flags = BF_EVACUATED; // it's a to-space block - stp->hp = bd->start; - stp->hpLim = stp->hp + BLOCK_SIZE_W; - stp->hp_bd = bd; - stp->to_blocks = bd; - stp->n_to_blocks = 1; + + // start a new to-space for this step. + stp->old_blocks = stp->blocks; + stp->n_old_blocks = stp->n_blocks; + + // allocate the first to-space block; extra blocks will be + // chained on as necessary. + stp->hp_bd = NULL; + bd = gc_alloc_block(stp); + stp->blocks = bd; + stp->n_blocks = 1; stp->scan = bd->start; stp->scan_bd = bd; + + // allocate a block for "already scavenged" objects. This goes + // on the front of the stp->blocks list, so it won't be + // traversed by the scavenging sweep. + gc_alloc_scavd_block(stp); + + // initialise the large object queues. stp->new_large_objects = NULL; stp->scavenged_large_objects = NULL; stp->n_scavenged_large_blocks = 0; - new_blocks++; + // mark the large objects as not evacuated yet for (bd = stp->large_objects; bd; bd = bd->link) { - bd->flags = BF_LARGE; + bd->flags &= ~BF_EVACUATED; } // for a compacted step, we need to allocate the bitmap @@ -362,25 +507,32 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) bdescr *bitmap_bdescr; StgWord *bitmap; - bitmap_size = stp->n_blocks * BLOCK_SIZE / (sizeof(W_)*BITS_PER_BYTE); + bitmap_size = stp->n_old_blocks * BLOCK_SIZE / (sizeof(W_)*BITS_PER_BYTE); if (bitmap_size > 0) { - bitmap_bdescr = allocGroup((nat)BLOCK_ROUND_UP(bitmap_size) + bitmap_bdescr = allocGroup((lnat)BLOCK_ROUND_UP(bitmap_size) / BLOCK_SIZE); stp->bitmap = bitmap_bdescr; bitmap = bitmap_bdescr->start; - IF_DEBUG(gc, belch("bitmap_size: %d, bitmap: %p", + IF_DEBUG(gc, debugBelch("bitmap_size: %d, bitmap: %p", bitmap_size, bitmap);); // don't forget to fill it with zeros! memset(bitmap, 0, bitmap_size); - // for each block in this step, point to its bitmap from the + // For each block in this step, point to its bitmap from the // block descriptor. - for (bd=stp->blocks; bd != NULL; bd = bd->link) { + for (bd=stp->old_blocks; bd != NULL; bd = bd->link) { bd->u.bitmap = bitmap; bitmap += BLOCK_SIZE_W / (sizeof(W_)*BITS_PER_BYTE); + + // Also at this point we set the BF_COMPACTED flag + // for this block. The invariant is that + // BF_COMPACTED is always unset, except during GC + // when it is set on those blocks which will be + // compacted. + bd->flags |= BF_COMPACTED; } } } @@ -388,35 +540,42 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) } /* make sure the older generations have at least one block to - * allocate into (this makes things easier for copy(), see below. + * allocate into (this makes things easier for copy(), see below). */ for (g = N+1; g < RtsFlags.GcFlags.generations; g++) { for (s = 0; s < generations[g].n_steps; s++) { stp = &generations[g].steps[s]; if (stp->hp_bd == NULL) { ASSERT(stp->blocks == NULL); - bd = allocBlock(); - bd->gen_no = g; - bd->step = stp; - bd->link = NULL; - bd->flags = 0; // *not* a to-space block or a large object - stp->hp = bd->start; - stp->hpLim = stp->hp + BLOCK_SIZE_W; - stp->hp_bd = bd; + bd = gc_alloc_block(stp); stp->blocks = bd; stp->n_blocks = 1; - new_blocks++; + } + if (stp->scavd_hp == NULL) { + gc_alloc_scavd_block(stp); + stp->n_blocks++; } /* Set the scan pointer for older generations: remember we * still have to scavenge objects that have been promoted. */ stp->scan = stp->hp; stp->scan_bd = stp->hp_bd; - stp->to_blocks = NULL; - stp->n_to_blocks = 0; stp->new_large_objects = NULL; stp->scavenged_large_objects = NULL; stp->n_scavenged_large_blocks = 0; } + + /* Move the private mutable lists from each capability onto the + * main mutable list for the generation. + */ + for (i = 0; i < n_capabilities; i++) { + for (bd = capabilities[i].mut_lists[g]; + bd->link != NULL; bd = bd->link) { + /* nothing */ + } + bd->link = generations[g].mut_list; + generations[g].mut_list = capabilities[i].mut_lists[g]; + capabilities[i].mut_lists[g] = allocBlock(); + } } /* Allocate a mark stack if we're doing a major collection. @@ -430,6 +589,8 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) mark_stack_bdescr = NULL; } + eager_promotion = rtsTrue; // for now + /* ----------------------------------------------------------------------- * follow all the roots that we know about: * - mutable lists from each generation > N @@ -446,23 +607,12 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) int st; for (g = RtsFlags.GcFlags.generations-1; g > N; g--) { generations[g].saved_mut_list = generations[g].mut_list; - generations[g].mut_list = END_MUT_LIST; - } - - // Do the mut-once lists first - for (g = RtsFlags.GcFlags.generations-1; g > N; g--) { - IF_PAR_DEBUG(verbose, - printMutOnceList(&generations[g])); - scavenge_mut_once_list(&generations[g]); - evac_gen = g; - for (st = generations[g].n_steps-1; st >= 0; st--) { - scavenge(&generations[g].steps[st]); - } + generations[g].mut_list = allocBlock(); + // mut_list always has at least one block. } for (g = RtsFlags.GcFlags.generations-1; g > N; g--) { - IF_PAR_DEBUG(verbose, - printMutableList(&generations[g])); + IF_PAR_DEBUG(verbose, printMutableList(&generations[g])); scavenge_mutable_list(&generations[g]); evac_gen = g; for (st = generations[g].n_steps-1; st >= 0; st--) { @@ -515,17 +665,6 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) */ markStablePtrTable(mark_root); -#ifdef INTERPRETER - { - /* ToDo: To fix the caf leak, we need to make the commented out - * parts of this code do something sensible - as described in - * the CAF document. - */ - extern void markHugsObjects(void); - markHugsObjects(); - } -#endif - /* ------------------------------------------------------------------------- * Repeatedly scavenge all the areas we know about until there's no * more scavenging to be done. @@ -593,7 +732,7 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) } } - /* Update the pointers from the "main thread" list - these are + /* 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 @@ -601,14 +740,23 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) * updating pointers here. */ { - StgMainThread *m; + Task *task; StgTSO *tso; - for (m = main_threads; m != NULL; m = m->link) { - tso = (StgTSO *) isAlive((StgClosure *)m->tso); - if (tso == NULL) { - barf("main thread has been GC'd"); + 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; } - m->tso = tso; } } @@ -626,8 +774,9 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) for (s = 0; s < generations[g].n_steps; s++) { stp = &generations[g].steps[s]; if (!(g == 0 && s == 0 && RtsFlags.GcFlags.generations > 1)) { + ASSERT(Bdescr(stp->hp) == stp->hp_bd); stp->hp_bd->free = stp->hp; - stp->hp_bd->link = NULL; + Bdescr(stp->scavd_hp)->free = stp->scavd_hp; } } } @@ -644,7 +793,7 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) // Finally: compaction of the oldest generation. if (major_gc && oldest_gen->steps[0].is_compacted) { // save number of blocks for stats - oldgen_saved_blocks = oldest_gen->steps[0].n_blocks; + oldgen_saved_blocks = oldest_gen->steps[0].n_old_blocks; compact(get_roots); } @@ -653,12 +802,25 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) /* run through all the generations/steps and tidy up */ copied = new_blocks * BLOCK_SIZE_W; + scavd_copied = new_scavd_blocks * BLOCK_SIZE_W; for (g = 0; g < RtsFlags.GcFlags.generations; g++) { if (g <= N) { generations[g].collections++; // for stats } + // Count the mutable list as bytes "copied" for the purposes of + // stats. Every mutable list is copied during every GC. + if (g > 0) { + nat mut_list_size = 0; + for (bd = generations[g].mut_list; bd != NULL; bd = bd->link) { + mut_list_size += bd->free - bd->start; + } + copied += mut_list_size; + + IF_DEBUG(gc, debugBelch("mut_list_size: %ld (%d vars, %d arrays, %d others)\n", mut_list_size * sizeof(W_), mutlist_MUTVARS, mutlist_MUTARRS, mutlist_OTHERS)); + } + for (s = 0; s < generations[g].n_steps; s++) { bdescr *next; stp = &generations[g].steps[s]; @@ -668,19 +830,13 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) if (g <= N) { copied -= stp->hp_bd->start + BLOCK_SIZE_W - stp->hp_bd->free; + scavd_copied -= (P_)(BLOCK_ROUND_UP(stp->scavd_hp)) - stp->scavd_hp; } } // for generations we collected... if (g <= N) { - // rough calculation of garbage collected, for stats output - if (stp->is_compacted) { - collected += (oldgen_saved_blocks - stp->n_blocks) * BLOCK_SIZE_W; - } else { - collected += stp->n_blocks * BLOCK_SIZE_W; - } - /* free old memory and shift to-space into from-space for all * the collected steps (except the allocation area). These * freed blocks will probaby be quickly recycled. @@ -689,32 +845,35 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) if (stp->is_compacted) { // for a compacted step, just shift the new to-space // onto the front of the now-compacted existing blocks. - for (bd = stp->to_blocks; bd != NULL; bd = bd->link) { - bd->flags &= ~BF_EVACUATED; // now from-space + for (bd = stp->blocks; bd != NULL; bd = bd->link) { + bd->flags &= ~BF_EVACUATED; // now from-space } // tack the new blocks on the end of the existing blocks - if (stp->blocks == NULL) { - stp->blocks = stp->to_blocks; - } else { - for (bd = stp->blocks; bd != NULL; bd = next) { + if (stp->old_blocks != NULL) { + for (bd = stp->old_blocks; bd != NULL; bd = next) { + // NB. this step might not be compacted next + // time, so reset the BF_COMPACTED flags. + // They are set before GC if we're going to + // compact. (search for BF_COMPACTED above). + bd->flags &= ~BF_COMPACTED; next = bd->link; if (next == NULL) { - bd->link = stp->to_blocks; + bd->link = stp->blocks; } } + stp->blocks = stp->old_blocks; } // add the new blocks to the block tally - stp->n_blocks += stp->n_to_blocks; + stp->n_blocks += stp->n_old_blocks; + ASSERT(countBlocks(stp->blocks) == stp->n_blocks); } else { - freeChain(stp->blocks); - stp->blocks = stp->to_blocks; - stp->n_blocks = stp->n_to_blocks; + freeChain(stp->old_blocks); for (bd = stp->blocks; bd != NULL; bd = bd->link) { - bd->flags &= ~BF_EVACUATED; // now from-space + bd->flags &= ~BF_EVACUATED; // now from-space } } - stp->to_blocks = NULL; - stp->n_to_blocks = 0; + stp->old_blocks = NULL; + stp->n_old_blocks = 0; } /* LARGE OBJECTS. The current live large objects are chained on @@ -749,7 +908,6 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) } // add the new blocks we promoted during this GC - stp->n_blocks += stp->n_to_blocks; stp->n_large_blocks += stp->n_scavenged_large_blocks; } } @@ -787,10 +945,10 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) oldest_gen->steps[0].n_blocks > (RtsFlags.GcFlags.compactThreshold * max) / 100))) { oldest_gen->steps[0].is_compacted = 1; -// fprintf(stderr,"compaction: on\n", live); +// debugBelch("compaction: on\n", live); } else { oldest_gen->steps[0].is_compacted = 0; -// fprintf(stderr,"compaction: off\n", live); +// debugBelch("compaction: off\n", live); } // if we're going to go over the maximum heap size, reduce the @@ -822,7 +980,7 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) } #if 0 - fprintf(stderr,"live: %d, min_alloc: %d, size : %d, max = %d\n", live, + debugBelch("live: %d, min_alloc: %d, size : %d, max = %d\n", live, min_alloc, size, max); #endif @@ -860,8 +1018,9 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) for (g = 0; g <= N; g++) { for (s = 0; s < generations[g].n_steps; s++) { stp = &generations[g].steps[s]; - if (stp->is_compacted && stp->bitmap != NULL) { + if (stp->bitmap != NULL) { freeGroup(stp->bitmap); + stp->bitmap = NULL; } } } @@ -872,12 +1031,16 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) if (RtsFlags.GcFlags.generations == 1) { nat blocks; - if (old_to_blocks != NULL) { - freeChain(old_to_blocks); + if (g0s0->old_blocks != NULL) { + freeChain(g0s0->old_blocks); } - for (bd = g0s0->to_blocks; bd != NULL; bd = bd->link) { + for (bd = g0s0->blocks; bd != NULL; bd = bd->link) { bd->flags = 0; // now from-space } + g0s0->old_blocks = g0s0->blocks; + g0s0->n_old_blocks = g0s0->n_blocks; + g0s0->blocks = saved_nursery; + g0s0->n_blocks = saved_n_blocks; /* For a two-space collector, we need to resize the nursery. */ @@ -895,7 +1058,7 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) * performance we get from 3L bytes, reducing to the same * performance at 2L bytes. */ - blocks = g0s0->n_to_blocks; + blocks = g0s0->n_old_blocks; if ( RtsFlags.GcFlags.maxHeapSize != 0 && blocks * RtsFlags.GcFlags.oldGenFactor * 2 > @@ -904,7 +1067,7 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) int pc_free; adjusted_blocks = (RtsFlags.GcFlags.maxHeapSize - 2 * blocks); - IF_DEBUG(gc, belch("@@ Near maximum heap size of 0x%x blocks, blocks = %d, adjusted to %ld", RtsFlags.GcFlags.maxHeapSize, blocks, adjusted_blocks)); + IF_DEBUG(gc, debugBelch("@@ Near maximum heap size of 0x%x blocks, blocks = %d, adjusted to %ld", RtsFlags.GcFlags.maxHeapSize, blocks, adjusted_blocks)); pc_free = adjusted_blocks * 100 / RtsFlags.GcFlags.maxHeapSize; if (pc_free < RtsFlags.GcFlags.pcFreeHeap) /* might even be < 0 */ { heapOverflow(); @@ -917,7 +1080,7 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) blocks = RtsFlags.GcFlags.minAllocAreaSize; } } - resizeNursery(blocks); + resizeNurseries(blocks); } else { /* Generational collector: @@ -934,7 +1097,7 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) * percentage of g0s0 that was live at the last minor GC. */ if (N == 0) { - g0s0_pcnt_kept = (new_blocks * 100) / g0s0->n_blocks; + g0s0_pcnt_kept = (new_blocks * 100) / countNurseryBlocks(); } /* Estimate a size for the allocation area based on the @@ -957,12 +1120,12 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) blocks = RtsFlags.GcFlags.minAllocAreaSize; } - resizeNursery((nat)blocks); + resizeNurseries((nat)blocks); } else { // we might have added extra large blocks to the nursery, so // resize back to minAllocAreaSize again. - resizeNursery(RtsFlags.GcFlags.minAllocAreaSize); + resizeNurseriesFixed(RtsFlags.GcFlags.minAllocAreaSize); } } @@ -985,16 +1148,16 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) // Reset the nursery resetNurseries(); - RELEASE_LOCK(&sched_mutex); - // start any pending finalizers - scheduleFinalizers(old_weak_ptr_list); + RELEASE_SM_LOCK; + scheduleFinalizers(last_free_capability, old_weak_ptr_list); + ACQUIRE_SM_LOCK; - ACQUIRE_LOCK(&sched_mutex); - // 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); @@ -1014,8 +1177,10 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) CCCS = prev_CCS; #endif - // check for memory leaks if sanity checking is on - IF_DEBUG(sanity, memInventory()); +#ifdef DEBUG + // check for memory leaks if DEBUG is on + memInventory(); +#endif #ifdef RTS_GTK_FRONTPANEL if (RtsFlags.GcFlags.frontpanel) { @@ -1024,7 +1189,14 @@ GarbageCollect ( void (*get_roots)(evac_fn), rtsBool force_major_gc ) #endif // ok, GC over: tell the stats department what happened. - stat_endGC(allocated, collected, live, copied, N); + stat_endGC(allocated, live, copied, scavd_copied, N); + +#if defined(RTS_USER_SIGNALS) + // unblock signals again + unblockUserSignals(); +#endif + + RELEASE_SM_LOCK; //PAR_TICKY_TP(); } @@ -1104,31 +1276,41 @@ traverse_weak_ptr_list(void) continue; } - ASSERT(get_itbl(w)->type == WEAK); - - /* Now, check whether the key is reachable. - */ - new = isAlive(w->key); - if (new != NULL) { - w->key = new; - // evacuate the value and finalizer - w->value = evacuate(w->value); - w->finalizer = evacuate(w->finalizer); - // remove this weak ptr from the old_weak_ptr list - *last_w = w->link; - // and put it on the new weak ptr list - next_w = w->link; - w->link = weak_ptr_list; - weak_ptr_list = w; - flag = rtsTrue; - IF_DEBUG(weak, belch("Weak pointer still alive at %p -> %p", - w, w->key)); - continue; - } - else { - last_w = &(w->link); - next_w = w->link; + switch (get_itbl(w)->type) { + + case EVACUATED: + next_w = (StgWeak *)((StgEvacuated *)w)->evacuee; + *last_w = next_w; continue; + + case WEAK: + /* Now, check whether the key is reachable. + */ + new = isAlive(w->key); + if (new != NULL) { + w->key = new; + // evacuate the value and finalizer + w->value = evacuate(w->value); + w->finalizer = evacuate(w->finalizer); + // remove this weak ptr from the old_weak_ptr list + *last_w = w->link; + // and put it on the new weak ptr list + next_w = w->link; + w->link = weak_ptr_list; + weak_ptr_list = w; + flag = rtsTrue; + IF_DEBUG(weak, debugBelch("Weak pointer still alive at %p -> %p", + w, w->key)); + continue; + } + else { + last_w = &(w->link); + next_w = w->link; + continue; + } + + default: + barf("traverse_weak_ptr_list: not WEAK"); } } @@ -1159,7 +1341,7 @@ traverse_weak_ptr_list(void) prev = &old_all_threads; for (t = old_all_threads; t != END_TSO_QUEUE; t = next) { - (StgClosure *)tmp = isAlive((StgClosure *)t); + tmp = (StgTSO *)isAlive((StgClosure *)t); if (tmp != NULL) { t = tmp; @@ -1184,6 +1366,16 @@ traverse_weak_ptr_list(void) ; } + // Threads blocked on black holes: if the black hole + // is alive, then the thread is alive too. + if (tmp == NULL && t->why_blocked == BlockedOnBlackHole) { + if (isAlive(t->block_info.closure)) { + t = (StgTSO *)evacuate((StgClosure *)t); + tmp = t; + flag = rtsTrue; + } + } + if (tmp == NULL) { // not alive (yet): leave this thread on the // old_all_threads list. @@ -1200,23 +1392,43 @@ traverse_weak_ptr_list(void) } } + /* 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; - (StgClosure *)tmp = evacuate((StgClosure *)t); + 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; } } @@ -1241,7 +1453,10 @@ mark_weak_ptr_list ( StgWeak **list ) last_w = list; for (w = *list; w; w = w->link) { - (StgClosure *)w = evacuate((StgClosure *)w); + // w might be WEAK, EVACUATED, or DEAD_WEAK (actually CON_STATIC) here + ASSERT(w->header.info == &stg_DEAD_WEAK_info + || get_itbl(w)->type == WEAK || get_itbl(w)->type == EVACUATED); + w = (StgWeak *)evacuate((StgClosure *)w); *last_w = w; last_w = &(w->link); } @@ -1264,29 +1479,37 @@ isAlive(StgClosure *p) while (1) { + ASSERT(LOOKS_LIKE_CLOSURE_PTR(p)); info = get_itbl(p); - /* ToDo: for static closures, check the static link field. - * Problem here is that we sometimes don't set the link field, eg. - * for static closures with an empty SRT or CONSTR_STATIC_NOCAFs. - */ + // ignore static closures + // + // ToDo: for static closures, check the static link field. + // Problem here is that we sometimes don't set the link field, eg. + // for static closures with an empty SRT or CONSTR_STATIC_NOCAFs. + // + if (!HEAP_ALLOCED(p)) { + return p; + } - loop: - bd = Bdescr((P_)p); // ignore closures in generations that we're not collecting. - if (LOOKS_LIKE_STATIC(p) || bd->gen_no > N) { + bd = Bdescr((P_)p); + if (bd->gen_no > N) { return p; } - // large objects have an evacuated flag + + // 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) { - if (bd->flags & BF_EVACUATED) { - return p; - } else { - return NULL; - } + return NULL; } + // check the mark bit for compacted steps - if (bd->step->is_compacted && is_marked((P_)p,bd)) { + if ((bd->flags & BF_COMPACTED) && is_marked((P_)p,bd)) { return p; } @@ -1308,8 +1531,9 @@ isAlive(StgClosure *p) case TSO: if (((StgTSO *)p)->what_next == ThreadRelocated) { p = (StgClosure *)((StgTSO *)p)->link; - goto loop; - } + continue; + } + return NULL; default: // dead. @@ -1324,41 +1548,71 @@ mark_root(StgClosure **root) *root = evacuate(*root); } -static void -addBlock(step *stp) +STATIC_INLINE void +upd_evacuee(StgClosure *p, StgClosure *dest) { - bdescr *bd = allocBlock(); - bd->gen_no = stp->gen_no; - bd->step = stp; + // not true: (ToDo: perhaps it should be) + // ASSERT(Bdescr((P_)dest)->flags & BF_EVACUATED); + SET_INFO(p, &stg_EVACUATED_info); + ((StgEvacuated *)p)->evacuee = dest; +} - if (stp->gen_no <= N) { - bd->flags = BF_EVACUATED; - } else { - bd->flags = 0; + +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; + } } - stp->hp_bd->free = stp->hp; - stp->hp_bd->link = bd; - stp->hp = bd->start; - stp->hpLim = stp->hp + BLOCK_SIZE_W; - stp->hp_bd = bd; - stp->n_to_blocks++; - new_blocks++; -} + /* 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); -static __inline__ void -upd_evacuee(StgClosure *p, StgClosure *dest) -{ - p->header.info = &stg_EVACUATED_info; - ((StgEvacuated *)p)->evacuee = dest; +#ifdef PROFILING + // We store the size of the just evacuated object in the LDV word so that + // the profiler can guess the position of the next object later. + SET_EVACUAEE_FOR_LDV(from, size_org); +#endif + return (StgClosure *)to; } - -static __inline__ StgClosure * -copy(StgClosure *src, nat size, step *stp) +// Same as copy() above, except the object will be allocated in memory +// that will not be scavenged. Used for object that have no pointer +// fields. +STATIC_INLINE StgClosure * +copy_noscav(StgClosure *src, nat size, step *stp) { - P_ to, from, dest; + StgPtr to, from; + nat i; #ifdef PROFILING // @LDV profiling nat size_org = size; @@ -1371,33 +1625,34 @@ copy(StgClosure *src, nat size, step *stp) * by evacuate()). */ if (stp->gen_no < evac_gen) { -#ifdef NO_EAGER_PROMOTION - failed_to_evac = rtsTrue; -#else - stp = &generations[evac_gen].steps[0]; -#endif + if (eager_promotion) { + stp = &generations[evac_gen].steps[0]; + } else { + failed_to_evac = rtsTrue; + } } /* chain a new block onto the to-space for the destination step if * necessary. */ - if (stp->hp + size >= stp->hpLim) { - addBlock(stp); + if (stp->scavd_hp + size >= stp->scavd_hpLim) { + gc_alloc_scavd_block(stp); } - for(to = stp->hp, from = (P_)src; size>0; --size) { - *to++ = *from++; + 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); - dest = stp->hp; - stp->hp = to; - upd_evacuee(src,(StgClosure *)dest); #ifdef PROFILING // We store the size of the just evacuated object in the LDV word so that // the profiler can guess the position of the next object later. - SET_EVACUAEE_FOR_LDV(src, size_org); + SET_EVACUAEE_FOR_LDV(from, size_org); #endif - return (StgClosure *)dest; + return (StgClosure *)to; } /* Special version of copy() for when we only want to copy the info @@ -1417,15 +1672,15 @@ copyPart(StgClosure *src, nat size_to_reserve, nat size_to_copy, step *stp) TICK_GC_WORDS_COPIED(size_to_copy); if (stp->gen_no < evac_gen) { -#ifdef NO_EAGER_PROMOTION - failed_to_evac = rtsTrue; -#else - stp = &generations[evac_gen].steps[0]; -#endif + if (eager_promotion) { + stp = &generations[evac_gen].steps[0]; + } else { + failed_to_evac = rtsTrue; + } } if (stp->hp + size_to_reserve >= stp->hpLim) { - addBlock(stp); + gc_alloc_block(stp); } for(to = stp->hp, from = (P_)src; size_to_copy>0; --size_to_copy) { @@ -1443,7 +1698,7 @@ copyPart(StgClosure *src, nat size_to_reserve, nat size_to_copy, step *stp) SET_EVACUAEE_FOR_LDV(src, size_to_reserve); // fill the slop if (size_to_reserve - size_to_copy_org > 0) - FILL_SLOP(stp->hp - 1, (int)(size_to_reserve - size_to_copy_org)); + LDV_FILL_SLOP(stp->hp - 1, (int)(size_to_reserve - size_to_copy_org)); #endif return (StgClosure *)dest; } @@ -1453,15 +1708,15 @@ copyPart(StgClosure *src, nat size_to_reserve, nat size_to_copy, step *stp) Evacuate a large object This just consists of removing the object from the (doubly-linked) - large_alloc_list, and linking it on to the (singly-linked) - new_large_objects list, from where it will be scavenged later. + step->large_objects list, and linking it on to the (singly-linked) + step->new_large_objects list, from where it will be scavenged later. Convention: bd->flags has BF_EVACUATED set for a large object that has been evacuated, or unset otherwise. -------------------------------------------------------------------------- */ -static inline void +STATIC_INLINE void evacuate_large(StgPtr p) { bdescr *bd = Bdescr(p); @@ -1498,11 +1753,11 @@ evacuate_large(StgPtr p) */ stp = bd->step->to; if (stp->gen_no < evac_gen) { -#ifdef NO_EAGER_PROMOTION - failed_to_evac = rtsTrue; -#else - stp = &generations[evac_gen].steps[0]; -#endif + if (eager_promotion) { + stp = &generations[evac_gen].steps[0]; + } else { + failed_to_evac = rtsTrue; + } } bd->step = stp; @@ -1513,40 +1768,6 @@ evacuate_large(StgPtr p) } /* ----------------------------------------------------------------------------- - Adding a MUT_CONS to an older generation. - - This is necessary from time to time when we end up with an - old-to-new generation pointer in a non-mutable object. We defer - the promotion until the next GC. - -------------------------------------------------------------------------- */ - - -static StgClosure * -mkMutCons(StgClosure *ptr, generation *gen) -{ - StgMutVar *q; - step *stp; - - stp = &gen->steps[0]; - - /* chain a new block onto the to-space for the destination step if - * necessary. - */ - if (stp->hp + sizeofW(StgIndOldGen) >= stp->hpLim) { - addBlock(stp); - } - - q = (StgMutVar *)stp->hp; - stp->hp += sizeofW(StgMutVar); - - SET_HDR(q,&stg_MUT_CONS_info,CCS_GC); - q->var = ptr; - recordOldToNewPtrs((StgMutClosure *)q); - - return (StgClosure *)q; -} - -/* ----------------------------------------------------------------------------- Evacuate This is called (eventually) for every live object in the system. @@ -1569,82 +1790,163 @@ mkMutCons(StgClosure *ptr, generation *gen) if M < evac_gen set failed_to_evac flag to indicate that we didn't manage to evacuate this object into evac_gen. + + OPTIMISATION NOTES: + + evacuate() is the single most important function performance-wise + in the GC. Various things have been tried to speed it up, but as + far as I can tell the code generated by gcc 3.2 with -O2 is about + as good as it's going to get. We pass the argument to evacuate() + in a register using the 'regparm' attribute (see the prototype for + evacuate() near the top of this file). + + Changing evacuate() to take an (StgClosure **) rather than + returning the new pointer seems attractive, because we can avoid + writing back the pointer when it hasn't changed (eg. for a static + object, or an object in a generation > N). However, I tried it and + it doesn't help. One reason is that the (StgClosure **) pointer + gets spilled to the stack inside evacuate(), resulting in far more + extra reads/writes than we save. -------------------------------------------------------------------------- */ -static StgClosure * +REGPARM1 static StgClosure * evacuate(StgClosure *q) { +#if defined(PAR) StgClosure *to; +#endif bdescr *bd = NULL; step *stp; const StgInfoTable *info; loop: - if (HEAP_ALLOCED(q)) { - bd = Bdescr((P_)q); - - // not a group head: find the group head - if (bd->blocks == 0) { bd = bd->link; } - - 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; - } + ASSERT(LOOKS_LIKE_CLOSURE_PTR(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 (!HEAP_ALLOCED(q)) { - /* If the object is in a step that we're compacting, then we - * need to use an alternative evacuate procedure. - */ - if (bd->step->is_compacted) { - if (!is_marked((P_)q,bd)) { - mark((P_)q,bd); - if (mark_stack_full()) { - mark_stack_overflowed = rtsTrue; - reset_mark_stack(); - } - push_mark_stack((P_)q); - } - return q; - } + if (!major_gc) return q; - stp = bd->step->to; - } -#ifdef DEBUG - else stp = NULL; // make sure copy() will crash if HEAP_ALLOCED is wrong -#endif + info = get_itbl(q); + switch (info->type) { - // make sure the info pointer is into text space - ASSERT(q && (LOOKS_LIKE_GHC_INFO(GET_INFO(q)) - || IS_HUGS_CONSTR_INFO(GET_INFO(q)))); - info = get_itbl(q); + case THUNK_STATIC: + if (info->srt_bitmap != 0 && + *THUNK_STATIC_LINK((StgClosure *)q) == NULL) { + *THUNK_STATIC_LINK((StgClosure *)q) = static_objects; + static_objects = (StgClosure *)q; + } + return q; + + case FUN_STATIC: + if (info->srt_bitmap != 0 && + *FUN_STATIC_LINK((StgClosure *)q) == NULL) { + *FUN_STATIC_LINK((StgClosure *)q) = static_objects; + static_objects = (StgClosure *)q; + } + return q; + + case IND_STATIC: + /* If q->saved_info != NULL, then it's a revertible CAF - it'll be + * on the CAF list, so don't do anything with it here (we'll + * scavenge it later). + */ + if (((StgIndStatic *)q)->saved_info == NULL + && *IND_STATIC_LINK((StgClosure *)q) == NULL) { + *IND_STATIC_LINK((StgClosure *)q) = static_objects; + static_objects = (StgClosure *)q; + } + return q; + + case CONSTR_STATIC: + if (*STATIC_LINK(info,(StgClosure *)q) == NULL) { + *STATIC_LINK(info,(StgClosure *)q) = static_objects; + static_objects = (StgClosure *)q; + } + return q; + + case CONSTR_INTLIKE: + case CONSTR_CHARLIKE: + case CONSTR_NOCAF_STATIC: + /* no need to put these on the static linked list, they don't need + * to be scavenged. + */ + return q; + + default: + barf("evacuate(static): strange closure type %d", (int)(info->type)); + } + } + + 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) { + switch (info->type) { - case MUT_VAR: + case MUT_VAR_CLEAN: + case MUT_VAR_DIRTY: case MVAR: - to = copy(q,sizeW_fromITBL(info),stp); - return to; + return copy(q,sizeW_fromITBL(info),stp); case CONSTR_0_1: { @@ -1658,19 +1960,22 @@ loop: (StgInt)w >= MIN_INTLIKE && (StgInt)w <= MAX_INTLIKE) { return (StgClosure *)INTLIKE_CLOSURE((StgInt)w); } - // else, fall through ... + // else + return copy_noscav(q,sizeofW(StgHeader)+1,stp); } - case FUN_1_0: case FUN_0_1: + case FUN_1_0: case CONSTR_1_0: return copy(q,sizeofW(StgHeader)+1,stp); - case THUNK_1_0: // here because of MIN_UPD_SIZE + case THUNK_1_0: case THUNK_0_1: + return copy(q,sizeofW(StgThunk)+1,stp); + case THUNK_1_1: - case THUNK_0_2: case THUNK_2_0: + case THUNK_0_2: #ifdef NO_PROMOTE_THUNKS if (bd->gen_no == 0 && bd->step->no != 0 && @@ -1678,176 +1983,85 @@ loop: stp = bd->step; } #endif - return copy(q,sizeofW(StgHeader)+2,stp); + return copy(q,sizeofW(StgThunk)+2,stp); case FUN_1_1: - case FUN_0_2: case FUN_2_0: case CONSTR_1_1: - case CONSTR_0_2: case CONSTR_2_0: + case FUN_0_2: return copy(q,sizeofW(StgHeader)+2,stp); - case FUN: + case CONSTR_0_2: + return copy_noscav(q,sizeofW(StgHeader)+2,stp); + case THUNK: + return copy(q,thunk_sizeW_fromITBL(info),stp); + + case FUN: case CONSTR: case IND_PERM: case IND_OLDGEN_PERM: case WEAK: - case FOREIGN: case STABLE_NAME: - case BCO: return copy(q,sizeW_fromITBL(info),stp); + case BCO: + return copy(q,bco_sizeW((StgBCO *)q),stp); + case CAF_BLACKHOLE: case SE_CAF_BLACKHOLE: case SE_BLACKHOLE: case BLACKHOLE: return copyPart(q,BLACKHOLE_sizeW(),sizeofW(StgHeader),stp); - case BLACKHOLE_BQ: - to = copy(q,BLACKHOLE_sizeW(),stp); - return to; - case THUNK_SELECTOR: { - const StgInfoTable* selectee_info; - StgClosure* selectee = ((StgSelector*)q)->selectee; - - selector_loop: - selectee_info = get_itbl(selectee); - switch (selectee_info->type) { - case CONSTR: - case CONSTR_1_0: - case CONSTR_0_1: - case CONSTR_2_0: - case CONSTR_1_1: - case CONSTR_0_2: - case CONSTR_STATIC: - case CONSTR_NOCAF_STATIC: - { - StgWord offset = info->layout.selector_offset; - - // check that the size is in range - ASSERT(offset < - (StgWord32)(selectee_info->layout.payload.ptrs + - selectee_info->layout.payload.nptrs)); - - // perform the selection! - q = selectee->payload[offset]; - if (major_gc==rtsTrue) {TICK_GC_SEL_MAJOR();} else {TICK_GC_SEL_MINOR();} - - /* if we're already in to-space, there's no need to continue - * with the evacuation, just update the source address with - * a pointer to the (evacuated) constructor field. - */ - if (HEAP_ALLOCED(q)) { - bdescr *bd = Bdescr((P_)q); - if (bd->flags & BF_EVACUATED) { - if (bd->gen_no < evac_gen) { - failed_to_evac = rtsTrue; - TICK_GC_FAILED_PROMOTION(); - } - return q; - } - } + StgClosure *p; + const StgInfoTable *info_ptr; - /* otherwise, carry on and evacuate this constructor field, - * (but not the constructor itself) - */ - goto loop; + if (thunk_selector_depth > MAX_THUNK_SELECTOR_DEPTH) { + return copy(q,THUNK_SELECTOR_sizeW(),stp); } - case IND: - case IND_STATIC: - case IND_PERM: - case IND_OLDGEN: - case IND_OLDGEN_PERM: - selectee = ((StgInd *)selectee)->indirectee; - goto selector_loop; + // stashed away for LDV profiling, see below + info_ptr = q->header.info; - case EVACUATED: - selectee = ((StgEvacuated *)selectee)->evacuee; - goto selector_loop; + p = eval_thunk_selector(info->layout.selector_offset, + (StgSelector *)q); - case THUNK_SELECTOR: -# if 0 - /* Disabled 03 April 2001 by JRS; it seems to cause the GC (or - something) to go into an infinite loop when the nightly - stage2 compiles PrelTup.lhs. */ - - /* we can't recurse indefinitely in evacuate(), so set a - * limit on the number of times we can go around this - * loop. - */ - if (thunk_selector_depth < MAX_THUNK_SELECTOR_DEPTH) { - bdescr *bd; - bd = Bdescr((P_)selectee); - if (!bd->flags & BF_EVACUATED) { - thunk_selector_depth++; - selectee = evacuate(selectee); - thunk_selector_depth--; - goto selector_loop; - } - } else { - TICK_GC_SEL_ABANDONED(); - // and fall through... - } -# endif + if (p == NULL) { + return copy(q,THUNK_SELECTOR_sizeW(),stp); + } else { + StgClosure *val; + // q is still BLACKHOLE'd. + thunk_selector_depth++; + val = evacuate(p); + thunk_selector_depth--; - case AP_UPD: - case THUNK: - case THUNK_1_0: - case THUNK_0_1: - case THUNK_2_0: - case THUNK_1_1: - case THUNK_0_2: - case THUNK_STATIC: - case CAF_BLACKHOLE: - case SE_CAF_BLACKHOLE: - case SE_BLACKHOLE: - case BLACKHOLE: - case BLACKHOLE_BQ: - // not evaluated yet - break; +#ifdef PROFILING + // For the purposes of LDV profiling, we have destroyed + // the original selector thunk. + SET_INFO(q, info_ptr); + LDV_RECORD_DEAD_FILL_SLOP_DYNAMIC(q); +#endif -#if defined(PAR) - // a copy of the top-level cases below - case RBH: // cf. BLACKHOLE_BQ - { - //StgInfoTable *rip = get_closure_info(q, &size, &ptrs, &nonptrs, &vhs, str); - to = copy(q,BLACKHOLE_sizeW(),stp); - //ToDo: derive size etc from reverted IP - //to = copy(q,size,stp); - // recordMutable((StgMutClosure *)to); - return to; - } - - case BLOCKED_FETCH: - ASSERT(sizeofW(StgBlockedFetch) >= MIN_NONUPD_SIZE); - to = copy(q,sizeofW(StgBlockedFetch),stp); - return to; + // Update the THUNK_SELECTOR with an indirection to the + // EVACUATED closure now at p. Why do this rather than + // upd_evacuee(q,p)? Because we have an invariant that an + // EVACUATED closure always points to an object in the + // same or an older generation (required by the short-cut + // test in the EVACUATED case, below). + SET_INFO(q, &stg_IND_info); + ((StgInd *)q)->indirectee = p; -# ifdef DIST - case REMOTE_REF: -# endif - case FETCH_ME: - ASSERT(sizeofW(StgBlockedFetch) >= MIN_UPD_SIZE); - to = copy(q,sizeofW(StgFetchMe),stp); - return to; - - case FETCH_ME_BQ: - ASSERT(sizeofW(StgBlockedFetch) >= MIN_UPD_SIZE); - to = copy(q,sizeofW(StgFetchMeBlockingQueue),stp); - return to; -#endif + // For the purposes of LDV profiling, we have created an + // indirection. + LDV_RECORD_CREATE(q); - default: - barf("evacuate: THUNK_SELECTOR: strange selectee %d", - (int)(selectee_info->type)); - } + return val; + } } - return copy(q,THUNK_SELECTOR_sizeW(),stp); case IND: case IND_OLDGEN: @@ -1855,50 +2069,6 @@ loop: q = ((StgInd*)q)->indirectee; goto loop; - case THUNK_STATIC: - if (info->srt_len > 0 && major_gc && - THUNK_STATIC_LINK((StgClosure *)q) == NULL) { - THUNK_STATIC_LINK((StgClosure *)q) = static_objects; - static_objects = (StgClosure *)q; - } - return q; - - case FUN_STATIC: - if (info->srt_len > 0 && major_gc && - FUN_STATIC_LINK((StgClosure *)q) == NULL) { - FUN_STATIC_LINK((StgClosure *)q) = static_objects; - static_objects = (StgClosure *)q; - } - return q; - - case IND_STATIC: - /* If q->saved_info != NULL, then it's a revertible CAF - it'll be - * on the CAF list, so don't do anything with it here (we'll - * scavenge it later). - */ - if (major_gc - && ((StgIndStatic *)q)->saved_info == NULL - && IND_STATIC_LINK((StgClosure *)q) == NULL) { - IND_STATIC_LINK((StgClosure *)q) = static_objects; - static_objects = (StgClosure *)q; - } - return q; - - case CONSTR_STATIC: - if (major_gc && STATIC_LINK(info,(StgClosure *)q) == NULL) { - STATIC_LINK(info,(StgClosure *)q) = static_objects; - static_objects = (StgClosure *)q; - } - return q; - - case CONSTR_INTLIKE: - case CONSTR_CHARLIKE: - case CONSTR_NOCAF_STATIC: - /* no need to put these on the static linked list, they don't need - * to be scavenged. - */ - return q; - case RET_BCO: case RET_SMALL: case RET_VEC_SMALL: @@ -1908,17 +2078,21 @@ loop: case UPDATE_FRAME: case STOP_FRAME: case CATCH_FRAME: - case SEQ_FRAME: + case CATCH_STM_FRAME: + case CATCH_RETRY_FRAME: + case ATOMICALLY_FRAME: // shouldn't see these barf("evacuate: stack frame at %p\n", q); - case AP_UPD: case PAP: - /* PAPs and AP_UPDs are special - the payload is a copy of a chunk - * of stack, tagging and all. - */ return copy(q,pap_sizeW((StgPAP*)q),stp); + case AP: + return copy(q,ap_sizeW((StgAP*)q),stp); + + case AP_STACK: + return copy(q,ap_stack_sizeW((StgAP_STACK*)q),stp); + case EVACUATED: /* Already evacuated, just return the forwarding address. * HOWEVER: if the requested destination generation (evac_gen) is @@ -1927,9 +2101,18 @@ loop: * set the failed_to_evac flag to indicate that we couldn't * manage to promote the object to the desired generation. */ - if (evac_gen > 0) { // optimisation + /* + * Optimisation: the check is fairly expensive, but we can often + * shortcut it if either the required generation is 0, or the + * current object (the EVACUATED) is in a high enough generation. + * We know that an EVACUATED always points to an object in the + * same or an older generation. stp is the lowest step that the + * current object would be evacuated to, so we only do the full + * check if stp is too low. + */ + if (evac_gen > 0 && stp->gen_no < evac_gen) { // optimisation StgClosure *p = ((StgEvacuated*)q)->evacuee; - if (Bdescr((P_)p)->gen_no < evac_gen) { + if (HEAP_ALLOCED(p) && Bdescr((P_)p)->gen_no < evac_gen) { failed_to_evac = rtsTrue; TICK_GC_FAILED_PROMOTION(); } @@ -1938,10 +2121,12 @@ loop: case ARR_WORDS: // just copy the block - return copy(q,arr_words_sizeW((StgArrWords *)q),stp); + return copy_noscav(q,arr_words_sizeW((StgArrWords *)q),stp); - case MUT_ARR_PTRS: + case MUT_ARR_PTRS_CLEAN: + case MUT_ARR_PTRS_DIRTY: case MUT_ARR_PTRS_FROZEN: + case MUT_ARR_PTRS_FROZEN0: // just copy the block return copy(q,mut_arr_ptrs_sizeW((StgMutArrPtrs *)q),stp); @@ -1960,30 +2145,40 @@ loop: * list it contains. */ { - StgTSO *new_tso = (StgTSO *)copy((StgClosure *)tso,tso_sizeW(tso),stp); + StgTSO *new_tso; + StgPtr p, q; + + new_tso = (StgTSO *)copyPart((StgClosure *)tso, + tso_sizeW(tso), + sizeofW(StgTSO), stp); move_TSO(tso, new_tso); + for (p = tso->sp, q = new_tso->sp; + p < tso->stack+tso->stack_size;) { + *q++ = *p++; + } + return (StgClosure *)new_tso; } } #if defined(PAR) - case RBH: // cf. BLACKHOLE_BQ + case RBH: { //StgInfoTable *rip = get_closure_info(q, &size, &ptrs, &nonptrs, &vhs, str); to = copy(q,BLACKHOLE_sizeW(),stp); //ToDo: derive size etc from reverted IP //to = copy(q,size,stp); IF_DEBUG(gc, - belch("@@ evacuate: RBH %p (%s) to %p (%s)", + debugBelch("@@ evacuate: RBH %p (%s) to %p (%s)", q, info_type(q), to, info_type(to))); return to; } case BLOCKED_FETCH: - ASSERT(sizeofW(StgBlockedFetch) >= MIN_NONUPD_SIZE); + ASSERT(sizeofW(StgBlockedFetch) >= MIN_PAYLOD_SIZE); to = copy(q,sizeofW(StgBlockedFetch),stp); IF_DEBUG(gc, - belch("@@ evacuate: %p (%s) to %p (%s)", + debugBelch("@@ evacuate: %p (%s) to %p (%s)", q, info_type(q), to, info_type(to))); return to; @@ -1991,22 +2186,34 @@ loop: case REMOTE_REF: # endif case FETCH_ME: - ASSERT(sizeofW(StgBlockedFetch) >= MIN_UPD_SIZE); + ASSERT(sizeofW(StgBlockedFetch) >= MIN_PAYLOAD_SIZE); to = copy(q,sizeofW(StgFetchMe),stp); IF_DEBUG(gc, - belch("@@ evacuate: %p (%s) to %p (%s)", + debugBelch("@@ evacuate: %p (%s) to %p (%s)", q, info_type(q), to, info_type(to))); return to; case FETCH_ME_BQ: - ASSERT(sizeofW(StgBlockedFetch) >= MIN_UPD_SIZE); + ASSERT(sizeofW(StgBlockedFetch) >= MIN_PAYLOAD_SIZE); to = copy(q,sizeofW(StgFetchMeBlockingQueue),stp); IF_DEBUG(gc, - belch("@@ evacuate: %p (%s) to %p (%s)", + debugBelch("@@ evacuate: %p (%s) to %p (%s)", q, info_type(q), to, info_type(to))); return to; #endif + case TREC_HEADER: + return copy(q,sizeofW(StgTRecHeader),stp); + + case TVAR_WAIT_QUEUE: + return copy(q,sizeofW(StgTVarWaitQueue),stp); + + case TVAR: + return copy(q,sizeofW(StgTVar),stp); + + case TREC_CHUNK: + return copy(q,sizeofW(StgTRecChunk),stp); + default: barf("evacuate: strange closure type %d", (int)(info->type)); } @@ -2015,200 +2222,572 @@ loop: } /* ----------------------------------------------------------------------------- - move_TSO is called to update the TSO structure after it has been - moved from one place to another. - -------------------------------------------------------------------------- */ + Evaluate a THUNK_SELECTOR if possible. -void -move_TSO(StgTSO *src, StgTSO *dest) -{ - ptrdiff_t diff; + returns: NULL if we couldn't evaluate this THUNK_SELECTOR, or + a closure pointer if we evaluated it and this is the result. Note + that "evaluating" the THUNK_SELECTOR doesn't necessarily mean + reducing it to HNF, just that we have eliminated the selection. + The result might be another thunk, or even another THUNK_SELECTOR. - // relocate the stack pointers... - diff = (StgPtr)dest - (StgPtr)src; // In *words* - dest->sp = (StgPtr)dest->sp + diff; - dest->su = (StgUpdateFrame *) ((P_)dest->su + diff); + If the return value is non-NULL, the original selector thunk has + been BLACKHOLE'd, and should be updated with an indirection or a + forwarding pointer. If the return value is NULL, then the selector + thunk is unchanged. - relocate_stack(dest, diff); -} + *** + ToDo: the treatment of THUNK_SELECTORS could be improved in the + following way (from a suggestion by Ian Lynagh): -/* ----------------------------------------------------------------------------- - relocate_stack is called to update the linkage between - UPDATE_FRAMEs (and SEQ_FRAMEs etc.) when a stack is moved from one - place to another. - -------------------------------------------------------------------------- */ + We can have a chain like this: -StgTSO * -relocate_stack(StgTSO *dest, ptrdiff_t diff) -{ - StgUpdateFrame *su; - StgCatchFrame *cf; - StgSeqFrame *sf; + sel_0 --> (a,b) + | + |-----> sel_0 --> (a,b) + | + |-----> sel_0 --> ... - su = dest->su; + and the depth limit means we don't go all the way to the end of the + chain, which results in a space leak. This affects the recursive + call to evacuate() in the THUNK_SELECTOR case in evacuate(): *not* + the recursive call to eval_thunk_selector() in + eval_thunk_selector(). - while ((P_)su < dest->stack + dest->stack_size) { - switch (get_itbl(su)->type) { - - // GCC actually manages to common up these three cases! + We could eliminate the depth bound in this case, in the following + way: - case UPDATE_FRAME: - su->link = (StgUpdateFrame *) ((StgPtr)su->link + diff); - su = su->link; - continue; + - traverse the chain once to discover the *value* of the + THUNK_SELECTOR. Mark all THUNK_SELECTORS that we + visit on the way as having been visited already (somehow). - case CATCH_FRAME: - cf = (StgCatchFrame *)su; - cf->link = (StgUpdateFrame *) ((StgPtr)cf->link + diff); - su = cf->link; - continue; + - in a second pass, traverse the chain again updating all + THUNK_SEELCTORS that we find on the way with indirections to + the value. - case SEQ_FRAME: - sf = (StgSeqFrame *)su; - sf->link = (StgUpdateFrame *) ((StgPtr)sf->link + diff); - su = sf->link; - continue; + - if we encounter a "marked" THUNK_SELECTOR in a normal + evacuate(), we konw it can't be updated so just evac it. - case STOP_FRAME: - // all done! - break; + Program that illustrates the problem: - default: - barf("relocate_stack %d", (int)(get_itbl(su)->type)); - } - break; - } + foo [] = ([], []) + foo (x:xs) = let (ys, zs) = foo xs + in if x >= 0 then (x:ys, zs) else (ys, x:zs) - return dest; -} + main = bar [1..(100000000::Int)] + bar xs = (\(ys, zs) -> print ys >> print zs) (foo xs) + -------------------------------------------------------------------------- */ +static inline rtsBool +is_to_space ( StgClosure *p ) +{ + bdescr *bd; + + bd = Bdescr((StgPtr)p); + if (HEAP_ALLOCED(p) && + ((bd->flags & BF_EVACUATED) + || ((bd->flags & BF_COMPACTED) && + is_marked((P_)p,bd)))) { + return rtsTrue; + } else { + return rtsFalse; + } +} -static inline void -scavenge_srt(const StgInfoTable *info) +static StgClosure * +eval_thunk_selector( nat field, StgSelector * p ) { - StgClosure **srt, **srt_end; + StgInfoTable *info; + const StgInfoTable *info_ptr; + StgClosure *selectee; + + selectee = p->selectee; - /* evacuate the SRT. If srt_len is zero, then there isn't an - * srt field in the info table. That's ok, because we'll - * never dereference it. - */ - srt = (StgClosure **)(info->srt); - srt_end = srt + info->srt_len; - for (; srt < srt_end; srt++) { - /* Special-case to handle references to closures hiding out in DLLs, since - double indirections required to get at those. The code generator knows - which is which when generating the SRT, so it stores the (indirect) - reference to the DLL closure in the table by first adding one to it. - We check for this here, and undo the addition before evacuating it. - - If the SRT entry hasn't got bit 0 set, the SRT entry points to a - closure that's fixed at link-time, and no extra magic is required. - */ -#ifdef ENABLE_WIN32_DLL_SUPPORT - if ( (unsigned long)(*srt) & 0x1 ) { - evacuate(*stgCast(StgClosure**,(stgCast(unsigned long, *srt) & ~0x1))); - } else { - evacuate(*srt); + // Save the real info pointer (NOTE: not the same as get_itbl()). + info_ptr = p->header.info; + + // If the THUNK_SELECTOR is in a generation that we are not + // collecting, then bail out early. We won't be able to save any + // space in any case, and updating with an indirection is trickier + // in an old gen. + if (Bdescr((StgPtr)p)->gen_no > N) { + return NULL; } -#else - evacuate(*srt); -#endif - } -} -/* ----------------------------------------------------------------------------- - Scavenge a TSO. - -------------------------------------------------------------------------- */ + // 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; + } -static void -scavengeTSO (StgTSO *tso) -{ - // chase the link field for any TSOs on the same queue - (StgClosure *)tso->link = evacuate((StgClosure *)tso->link); - if ( tso->why_blocked == BlockedOnMVar - || tso->why_blocked == BlockedOnBlackHole - || tso->why_blocked == BlockedOnException -#if defined(PAR) - || tso->why_blocked == BlockedOnGA - || tso->why_blocked == BlockedOnGA_NoSend -#endif - ) { - tso->block_info.closure = evacuate(tso->block_info.closure); - } - if ( tso->blocked_exceptions != NULL ) { - tso->blocked_exceptions = - (StgTSO *)evacuate((StgClosure *)tso->blocked_exceptions); - } - // scavenge this thread's stack - scavenge_stack(tso->sp, &(tso->stack[tso->stack_size])); -} + 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; + } + } -/* ----------------------------------------------------------------------------- - Scavenge a given step until there are no more objects in this step - to scavenge. + case IND: + case IND_PERM: + case IND_OLDGEN: + case IND_OLDGEN_PERM: + case IND_STATIC: + selectee = ((StgInd *)selectee)->indirectee; + goto selector_loop; - 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. + 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; - 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. - -------------------------------------------------------------------------- */ + case THUNK_SELECTOR: + { + StgClosure *val; -static void -scavenge(step *stp) -{ - StgPtr p, q; - StgInfoTable *info; - bdescr *bd; - nat saved_evac_gen = evac_gen; + // 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++; - p = stp->scan; - bd = stp->scan_bd; + val = eval_thunk_selector(info->layout.selector_offset, + (StgSelector *)selectee); - failed_to_evac = rtsFalse; + thunk_selector_depth--; - /* scavenge phase - standard breadth-first scavenging of the - * evacuated objects - */ + 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); - while (bd != stp->hp_bd || p < stp->hp) { + // For the purposes of LDV profiling, we have created an + // indirection. + LDV_RECORD_CREATE(selectee); - // 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; - } + selectee = val; + goto selector_loop; + } + } + + case AP: + case AP_STACK: + case THUNK: + case THUNK_1_0: + case THUNK_0_1: + case THUNK_2_0: + case THUNK_1_1: + case THUNK_0_2: + case THUNK_STATIC: + case CAF_BLACKHOLE: + case SE_CAF_BLACKHOLE: + case SE_BLACKHOLE: + case BLACKHOLE: +#if defined(PAR) + case RBH: + case BLOCKED_FETCH: +# ifdef DIST + case REMOTE_REF: +# endif + case FETCH_ME: + case FETCH_ME_BQ: +#endif + // not evaluated yet + break; + + default: + barf("eval_thunk_selector: strange selectee %d", + (int)(info->type)); + } + +bale_out: + // We didn't manage to evaluate this thunk; restore the old info pointer + SET_INFO(p, info_ptr); + return NULL; +} + +/* ----------------------------------------------------------------------------- + move_TSO is called to update the TSO structure after it has been + moved from one place to another. + -------------------------------------------------------------------------- */ + +void +move_TSO (StgTSO *src, StgTSO *dest) +{ + ptrdiff_t diff; + + // relocate the stack pointer... + diff = (StgPtr)dest - (StgPtr)src; // In *words* + dest->sp = (StgPtr)dest->sp + diff; +} + +/* Similar to scavenge_large_bitmap(), but we don't write back the + * pointers we get back from evacuate(). + */ +static void +scavenge_large_srt_bitmap( StgLargeSRT *large_srt ) +{ + nat i, b, size; + StgWord bitmap; + StgClosure **p; + + b = 0; + bitmap = large_srt->l.bitmap[b]; + size = (nat)large_srt->l.size; + p = (StgClosure **)large_srt->srt; + for (i = 0; i < size; ) { + if ((bitmap & 1) != 0) { + evacuate(*p); + } + i++; + p++; + if (i % BITS_IN(W_) == 0) { + b++; + bitmap = large_srt->l.bitmap[b]; + } else { + bitmap = bitmap >> 1; + } + } +} + +/* evacuate the SRT. If srt_bitmap is zero, then there isn't an + * srt field in the info table. That's ok, because we'll + * never dereference it. + */ +STATIC_INLINE void +scavenge_srt (StgClosure **srt, nat srt_bitmap) +{ + nat bitmap; + StgClosure **p; + + bitmap = srt_bitmap; + p = srt; + + if (bitmap == (StgHalfWord)(-1)) { + scavenge_large_srt_bitmap( (StgLargeSRT *)srt ); + return; + } + + while (bitmap != 0) { + if ((bitmap & 1) != 0) { +#ifdef ENABLE_WIN32_DLL_SUPPORT + // Special-case to handle references to closures hiding out in DLLs, since + // double indirections required to get at those. The code generator knows + // which is which when generating the SRT, so it stores the (indirect) + // reference to the DLL closure in the table by first adding one to it. + // We check for this here, and undo the addition before evacuating it. + // + // If the SRT entry hasn't got bit 0 set, the SRT entry points to a + // closure that's fixed at link-time, and no extra magic is required. + if ( (unsigned long)(*srt) & 0x1 ) { + evacuate(*stgCast(StgClosure**,(stgCast(unsigned long, *srt) & ~0x1))); + } else { + evacuate(*p); + } +#else + evacuate(*p); +#endif + } + p++; + bitmap = bitmap >> 1; + } +} + + +STATIC_INLINE void +scavenge_thunk_srt(const StgInfoTable *info) +{ + StgThunkInfoTable *thunk_info; + + if (!major_gc) return; + + thunk_info = itbl_to_thunk_itbl(info); + scavenge_srt((StgClosure **)GET_SRT(thunk_info), thunk_info->i.srt_bitmap); +} + +STATIC_INLINE void +scavenge_fun_srt(const StgInfoTable *info) +{ + StgFunInfoTable *fun_info; + + if (!major_gc) return; + + fun_info = itbl_to_fun_itbl(info); + scavenge_srt((StgClosure **)GET_FUN_SRT(fun_info), fun_info->i.srt_bitmap); +} + +/* ----------------------------------------------------------------------------- + Scavenge a TSO. + -------------------------------------------------------------------------- */ + +static void +scavengeTSO (StgTSO *tso) +{ + if ( tso->why_blocked == BlockedOnMVar + || tso->why_blocked == BlockedOnBlackHole + || tso->why_blocked == BlockedOnException +#if defined(PAR) + || tso->why_blocked == BlockedOnGA + || tso->why_blocked == BlockedOnGA_NoSend +#endif + ) { + tso->block_info.closure = evacuate(tso->block_info.closure); + } + if ( tso->blocked_exceptions != NULL ) { + tso->blocked_exceptions = + (StgTSO *)evacuate((StgClosure *)tso->blocked_exceptions); + } + + // We don't always chase the link field: TSOs on the blackhole + // queue are not automatically alive, so the link field is a + // "weak" pointer in that case. + if (tso->why_blocked != BlockedOnBlackHole) { + tso->link = (StgTSO *)evacuate((StgClosure *)tso->link); + } + + // scavange current transaction record + tso->trec = (StgTRecHeader *)evacuate((StgClosure *)tso->trec); + + // scavenge this thread's stack + scavenge_stack(tso->sp, &(tso->stack[tso->stack_size])); +} + +/* ----------------------------------------------------------------------------- + Blocks of function args occur on the stack (at the top) and + in PAPs. + -------------------------------------------------------------------------- */ + +STATIC_INLINE StgPtr +scavenge_arg_block (StgFunInfoTable *fun_info, StgClosure **args) +{ + StgPtr p; + StgWord bitmap; + nat size; + + p = (StgPtr)args; + switch (fun_info->f.fun_type) { + case ARG_GEN: + bitmap = BITMAP_BITS(fun_info->f.b.bitmap); + size = BITMAP_SIZE(fun_info->f.b.bitmap); + goto small_bitmap; + case ARG_GEN_BIG: + size = GET_FUN_LARGE_BITMAP(fun_info)->size; + scavenge_large_bitmap(p, GET_FUN_LARGE_BITMAP(fun_info), size); + p += size; + break; + default: + bitmap = BITMAP_BITS(stg_arg_bitmaps[fun_info->f.fun_type]); + size = BITMAP_SIZE(stg_arg_bitmaps[fun_info->f.fun_type]); + small_bitmap: + while (size > 0) { + if ((bitmap & 1) == 0) { + *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); + } + p++; + bitmap = bitmap >> 1; + size--; + } + break; + } + return p; +} + +STATIC_INLINE StgPtr +scavenge_PAP_payload (StgClosure *fun, StgClosure **payload, StgWord size) +{ + StgPtr p; + StgWord bitmap; + StgFunInfoTable *fun_info; + + fun_info = get_fun_itbl(fun); + ASSERT(fun_info->i.type != PAP); + p = (StgPtr)payload; + + switch (fun_info->f.fun_type) { + case ARG_GEN: + bitmap = BITMAP_BITS(fun_info->f.b.bitmap); + goto small_bitmap; + case ARG_GEN_BIG: + scavenge_large_bitmap(p, GET_FUN_LARGE_BITMAP(fun_info), size); + p += size; + break; + case ARG_BCO: + scavenge_large_bitmap((StgPtr)payload, BCO_BITMAP(fun), size); + p += size; + break; + default: + bitmap = BITMAP_BITS(stg_arg_bitmaps[fun_info->f.fun_type]); + small_bitmap: + while (size > 0) { + if ((bitmap & 1) == 0) { + *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); + } + p++; + bitmap = bitmap >> 1; + size--; + } + break; + } + return p; +} + +STATIC_INLINE StgPtr +scavenge_PAP (StgPAP *pap) +{ + pap->fun = evacuate(pap->fun); + return scavenge_PAP_payload (pap->fun, pap->payload, pap->n_args); +} + +STATIC_INLINE StgPtr +scavenge_AP (StgAP *ap) +{ + ap->fun = evacuate(ap->fun); + return scavenge_PAP_payload (ap->fun, ap->payload, ap->n_args); +} + +/* ----------------------------------------------------------------------------- + Scavenge a given step until there are no more objects in this step + to scavenge. + + evac_gen is set by the caller to be either zero (for a step in a + generation < N) or G where G is the generation of the step being + scavenged. + + We sometimes temporarily change evac_gen back to zero if we're + scavenging a mutable object where early promotion isn't such a good + idea. + -------------------------------------------------------------------------- */ + +static void +scavenge(step *stp) +{ + StgPtr p, q; + StgInfoTable *info; + bdescr *bd; + nat saved_evac_gen = evac_gen; + + p = stp->scan; + bd = stp->scan_bd; + + failed_to_evac = rtsFalse; + + /* scavenge phase - standard breadth-first scavenging of the + * evacuated objects + */ + + while (bd != stp->hp_bd || p < stp->hp) { + + // If we're at the end of this block, move on to the next block + if (bd != stp->hp_bd && p == bd->free) { + bd = bd->link; + p = bd->start; + continue; + } + + ASSERT(LOOKS_LIKE_CLOSURE_PTR(p)); + info = get_itbl((StgClosure *)p); + + ASSERT(thunk_selector_depth == 0); - info = get_itbl((StgClosure *)p); - ASSERT(p && (LOOKS_LIKE_GHC_INFO(info) || IS_HUGS_CONSTR_INFO(info))); - q = p; switch (info->type) { - + case MVAR: - /* treat MVars specially, because we don't want to evacuate the - * mut_link field in the middle of the closure. - */ { StgMVar *mvar = ((StgMVar *)p); evac_gen = 0; - (StgClosure *)mvar->head = evacuate((StgClosure *)mvar->head); - (StgClosure *)mvar->tail = evacuate((StgClosure *)mvar->tail); - (StgClosure *)mvar->value = evacuate((StgClosure *)mvar->value); + mvar->head = (StgTSO *)evacuate((StgClosure *)mvar->head); + mvar->tail = (StgTSO *)evacuate((StgClosure *)mvar->tail); + mvar->value = evacuate((StgClosure *)mvar->value); evac_gen = saved_evac_gen; - recordMutable((StgMutClosure *)mvar); - failed_to_evac = rtsFalse; // mutable. + failed_to_evac = rtsTrue; // mutable. p += sizeofW(StgMVar); break; } - case THUNK_2_0: case FUN_2_0: - scavenge_srt(info); + scavenge_fun_srt(info); + ((StgClosure *)p)->payload[1] = evacuate(((StgClosure *)p)->payload[1]); + ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]); + p += sizeofW(StgHeader) + 2; + break; + + case THUNK_2_0: + scavenge_thunk_srt(info); + ((StgThunk *)p)->payload[1] = evacuate(((StgThunk *)p)->payload[1]); + ((StgThunk *)p)->payload[0] = evacuate(((StgThunk *)p)->payload[0]); + p += sizeofW(StgThunk) + 2; + break; + case CONSTR_2_0: ((StgClosure *)p)->payload[1] = evacuate(((StgClosure *)p)->payload[1]); ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]); @@ -2216,65 +2795,95 @@ scavenge(step *stp) break; case THUNK_1_0: - scavenge_srt(info); - ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]); - p += sizeofW(StgHeader) + 2; // MIN_UPD_SIZE + scavenge_thunk_srt(info); + ((StgThunk *)p)->payload[0] = evacuate(((StgThunk *)p)->payload[0]); + p += sizeofW(StgThunk) + 1; break; case FUN_1_0: - scavenge_srt(info); + scavenge_fun_srt(info); case CONSTR_1_0: ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]); p += sizeofW(StgHeader) + 1; break; case THUNK_0_1: - scavenge_srt(info); - p += sizeofW(StgHeader) + 2; // MIN_UPD_SIZE + scavenge_thunk_srt(info); + p += sizeofW(StgThunk) + 1; break; case FUN_0_1: - scavenge_srt(info); + scavenge_fun_srt(info); case CONSTR_0_1: p += sizeofW(StgHeader) + 1; break; case THUNK_0_2: + scavenge_thunk_srt(info); + p += sizeofW(StgThunk) + 2; + break; + case FUN_0_2: - scavenge_srt(info); + scavenge_fun_srt(info); case CONSTR_0_2: p += sizeofW(StgHeader) + 2; break; case THUNK_1_1: + scavenge_thunk_srt(info); + ((StgThunk *)p)->payload[0] = evacuate(((StgThunk *)p)->payload[0]); + p += sizeofW(StgThunk) + 2; + break; + case FUN_1_1: - scavenge_srt(info); + scavenge_fun_srt(info); case CONSTR_1_1: ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]); p += sizeofW(StgHeader) + 2; break; case FUN: + scavenge_fun_srt(info); + goto gen_obj; + case THUNK: - scavenge_srt(info); - // fall through + { + StgPtr end; + + scavenge_thunk_srt(info); + end = (P_)((StgThunk *)p)->payload + info->layout.payload.ptrs; + for (p = (P_)((StgThunk *)p)->payload; p < end; p++) { + *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); + } + p += info->layout.payload.nptrs; + break; + } + gen_obj: case CONSTR: case WEAK: - case FOREIGN: case STABLE_NAME: - case BCO: { StgPtr end; end = (P_)((StgClosure *)p)->payload + info->layout.payload.ptrs; for (p = (P_)((StgClosure *)p)->payload; p < end; p++) { - (StgClosure *)*p = evacuate((StgClosure *)*p); + *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); } p += info->layout.payload.nptrs; break; } + case BCO: { + StgBCO *bco = (StgBCO *)p; + bco->instrs = (StgArrWords *)evacuate((StgClosure *)bco->instrs); + bco->literals = (StgArrWords *)evacuate((StgClosure *)bco->literals); + bco->ptrs = (StgMutArrPtrs *)evacuate((StgClosure *)bco->ptrs); + bco->itbls = (StgArrWords *)evacuate((StgClosure *)bco->itbls); + p += bco_sizeW(bco); + break; + } + case IND_PERM: if (stp->gen->no != 0) { #ifdef PROFILING @@ -2284,40 +2893,35 @@ scavenge(step *stp) LDV_recordDead((StgClosure *)p, sizeofW(StgInd)); #endif // - // Todo: maybe use SET_HDR() and remove LDV_recordCreate()? + // Todo: maybe use SET_HDR() and remove LDV_RECORD_CREATE()? // SET_INFO(((StgClosure *)p), &stg_IND_OLDGEN_PERM_info); -#ifdef PROFILING - // @LDV profiling + // We pretend that p has just been created. - LDV_recordCreate((StgClosure *)p); -#endif + LDV_RECORD_CREATE((StgClosure *)p); } // fall through case IND_OLDGEN_PERM: - ((StgIndOldGen *)p)->indirectee = - evacuate(((StgIndOldGen *)p)->indirectee); - if (failed_to_evac) { - failed_to_evac = rtsFalse; - recordOldToNewPtrs((StgMutClosure *)p); - } - p += sizeofW(StgIndOldGen); + ((StgInd *)p)->indirectee = evacuate(((StgInd *)p)->indirectee); + p += sizeofW(StgInd); break; - case MUT_VAR: - evac_gen = 0; + case MUT_VAR_CLEAN: + case MUT_VAR_DIRTY: { + rtsBool saved_eager_promotion = eager_promotion; + + eager_promotion = rtsFalse; ((StgMutVar *)p)->var = evacuate(((StgMutVar *)p)->var); - evac_gen = saved_evac_gen; - recordMutable((StgMutClosure *)p); - failed_to_evac = rtsFalse; // mutable anyhow - p += sizeofW(StgMutVar); - break; + eager_promotion = saved_eager_promotion; - case MUT_CONS: - // ignore these - failed_to_evac = rtsFalse; // mutable anyhow + if (failed_to_evac) { + ((StgClosure *)q)->header.info = &stg_MUT_VAR_DIRTY_info; + } else { + ((StgClosure *)q)->header.info = &stg_MUT_VAR_CLEAN_info; + } p += sizeofW(StgMutVar); break; + } case CAF_BLACKHOLE: case SE_CAF_BLACKHOLE: @@ -2326,17 +2930,6 @@ scavenge(step *stp) p += BLACKHOLE_sizeW(); break; - case BLACKHOLE_BQ: - { - StgBlockingQueue *bh = (StgBlockingQueue *)p; - (StgClosure *)bh->blocking_queue = - evacuate((StgClosure *)bh->blocking_queue); - recordMutable((StgMutClosure *)bh); - failed_to_evac = rtsFalse; - p += BLACKHOLE_sizeW(); - break; - } - case THUNK_SELECTOR: { StgSelector *s = (StgSelector *)p; @@ -2345,71 +2938,102 @@ scavenge(step *stp) break; } - case AP_UPD: // same as PAPs - case PAP: - /* Treat a PAP just like a section of stack, not forgetting to - * evacuate the function pointer too... - */ - { - StgPAP* pap = (StgPAP *)p; + // A chunk of stack saved in a heap object + case AP_STACK: + { + StgAP_STACK *ap = (StgAP_STACK *)p; - pap->fun = evacuate(pap->fun); - scavenge_stack((P_)pap->payload, (P_)pap->payload + pap->n_args); - p += pap_sizeW(pap); + ap->fun = evacuate(ap->fun); + scavenge_stack((StgPtr)ap->payload, (StgPtr)ap->payload + ap->size); + p = (StgPtr)ap->payload + ap->size; break; } - + + case PAP: + p = scavenge_PAP((StgPAP *)p); + break; + + case AP: + p = scavenge_AP((StgAP *)p); + break; + case ARR_WORDS: // nothing to follow p += arr_words_sizeW((StgArrWords *)p); break; - case MUT_ARR_PTRS: + case MUT_ARR_PTRS_CLEAN: + case MUT_ARR_PTRS_DIRTY: // follow everything { StgPtr next; - - evac_gen = 0; // repeatedly mutable + rtsBool saved_eager; + + // We don't eagerly promote objects pointed to by a mutable + // array, but if we find the array only points to objects in + // the same or an older generation, we mark it "clean" and + // avoid traversing it during minor GCs. + saved_eager = eager_promotion; + eager_promotion = rtsFalse; next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p); for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) { - (StgClosure *)*p = evacuate((StgClosure *)*p); + *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); } - evac_gen = saved_evac_gen; - recordMutable((StgMutClosure *)q); - failed_to_evac = rtsFalse; // mutable anyhow. + eager_promotion = saved_eager; + + if (failed_to_evac) { + ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_DIRTY_info; + } else { + ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_CLEAN_info; + } + + failed_to_evac = rtsTrue; // always put it on the mutable list. break; } case MUT_ARR_PTRS_FROZEN: + case MUT_ARR_PTRS_FROZEN0: // follow everything { StgPtr next; next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p); for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) { - (StgClosure *)*p = evacuate((StgClosure *)*p); + *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); + } + + // If we're going to put this object on the mutable list, then + // set its info ptr to MUT_ARR_PTRS_FROZEN0 to indicate that. + if (failed_to_evac) { + ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_FROZEN0_info; + } else { + ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_FROZEN_info; } - // it's tempting to recordMutable() if failed_to_evac is - // false, but that breaks some assumptions (eg. every - // closure on the mutable list is supposed to have the MUT - // flag set, and MUT_ARR_PTRS_FROZEN doesn't). break; } case TSO: { StgTSO *tso = (StgTSO *)p; - evac_gen = 0; + rtsBool saved_eager = eager_promotion; + + eager_promotion = rtsFalse; scavengeTSO(tso); - evac_gen = saved_evac_gen; - recordMutable((StgMutClosure *)tso); - failed_to_evac = rtsFalse; // mutable anyhow. + eager_promotion = saved_eager; + + if (failed_to_evac) { + tso->flags |= TSO_DIRTY; + } else { + tso->flags &= ~TSO_DIRTY; + } + + failed_to_evac = rtsTrue; // always on the mutable list p += tso_sizeW(tso); break; } #if defined(PAR) - case RBH: // cf. BLACKHOLE_BQ + case RBH: { #if 0 nat size, ptrs, nonptrs, vhs; @@ -2419,10 +3043,9 @@ scavenge(step *stp) StgRBH *rbh = (StgRBH *)p; (StgClosure *)rbh->blocking_queue = evacuate((StgClosure *)rbh->blocking_queue); - recordMutable((StgMutClosure *)to); - failed_to_evac = rtsFalse; // mutable anyhow. + failed_to_evac = rtsTrue; // mutable anyhow. IF_DEBUG(gc, - belch("@@ scavenge: RBH %p (%s) (new blocking_queue link=%p)", + debugBelch("@@ scavenge: RBH %p (%s) (new blocking_queue link=%p)", p, info_type(p), (StgClosure *)rbh->blocking_queue)); // ToDo: use size of reverted closure here! p += BLACKHOLE_sizeW(); @@ -2438,12 +3061,8 @@ scavenge(step *stp) // follow the link to the rest of the blocking queue (StgClosure *)bf->link = evacuate((StgClosure *)bf->link); - if (failed_to_evac) { - failed_to_evac = rtsFalse; - recordMutable((StgMutClosure *)bf); - } IF_DEBUG(gc, - belch("@@ scavenge: %p (%s); node is now %p; exciting, isn't it", + debugBelch("@@ scavenge: %p (%s); node is now %p; exciting, isn't it", bf, info_type((StgClosure *)bf), bf->node, info_type(bf->node))); p += sizeofW(StgBlockedFetch); @@ -2457,35 +3076,91 @@ scavenge(step *stp) p += sizeofW(StgFetchMe); break; // nothing to do in this case - case FETCH_ME_BQ: // cf. BLACKHOLE_BQ + case FETCH_ME_BQ: { StgFetchMeBlockingQueue *fmbq = (StgFetchMeBlockingQueue *)p; (StgClosure *)fmbq->blocking_queue = evacuate((StgClosure *)fmbq->blocking_queue); - if (failed_to_evac) { - failed_to_evac = rtsFalse; - recordMutable((StgMutClosure *)fmbq); - } IF_DEBUG(gc, - belch("@@ scavenge: %p (%s) exciting, isn't it", + debugBelch("@@ scavenge: %p (%s) exciting, isn't it", p, info_type((StgClosure *)p))); p += sizeofW(StgFetchMeBlockingQueue); break; } #endif + case TVAR_WAIT_QUEUE: + { + StgTVarWaitQueue *wq = ((StgTVarWaitQueue *) p); + evac_gen = 0; + wq->waiting_tso = (StgTSO *)evacuate((StgClosure*)wq->waiting_tso); + wq->next_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)wq->next_queue_entry); + wq->prev_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)wq->prev_queue_entry); + evac_gen = saved_evac_gen; + failed_to_evac = rtsTrue; // mutable + p += sizeofW(StgTVarWaitQueue); + break; + } + + case TVAR: + { + StgTVar *tvar = ((StgTVar *) p); + evac_gen = 0; + tvar->current_value = evacuate((StgClosure*)tvar->current_value); + tvar->first_wait_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)tvar->first_wait_queue_entry); + evac_gen = saved_evac_gen; + failed_to_evac = rtsTrue; // mutable + p += sizeofW(StgTVar); + break; + } + + case TREC_HEADER: + { + StgTRecHeader *trec = ((StgTRecHeader *) p); + evac_gen = 0; + trec->enclosing_trec = (StgTRecHeader *)evacuate((StgClosure*)trec->enclosing_trec); + trec->current_chunk = (StgTRecChunk *)evacuate((StgClosure*)trec->current_chunk); + evac_gen = saved_evac_gen; + failed_to_evac = rtsTrue; // mutable + p += sizeofW(StgTRecHeader); + break; + } + + case TREC_CHUNK: + { + StgWord i; + StgTRecChunk *tc = ((StgTRecChunk *) p); + TRecEntry *e = &(tc -> entries[0]); + evac_gen = 0; + tc->prev_chunk = (StgTRecChunk *)evacuate((StgClosure*)tc->prev_chunk); + for (i = 0; i < tc -> next_entry_idx; i ++, e++ ) { + e->tvar = (StgTVar *)evacuate((StgClosure*)e->tvar); + e->expected_value = evacuate((StgClosure*)e->expected_value); + e->new_value = evacuate((StgClosure*)e->new_value); + } + evac_gen = saved_evac_gen; + failed_to_evac = rtsTrue; // mutable + p += sizeofW(StgTRecChunk); + break; + } + default: barf("scavenge: unimplemented/strange closure type %d @ %p", info->type, p); } - /* If we didn't manage to promote all the objects pointed to by - * the current object, then we have to designate this object as - * mutable (because it contains old-to-new generation pointers). + /* + * We need to record the current object on the mutable list if + * (a) It is actually mutable, or + * (b) It contains pointers to a younger generation. + * Case (b) arises if we didn't manage to promote everything that + * the current object points to into the current generation. */ if (failed_to_evac) { failed_to_evac = rtsFalse; - mkMutCons((StgClosure *)q, &generations[evac_gen]); + if (stp->gen_no > 0) { + recordMutableGen((StgClosure *)q, stp->gen); + } } } @@ -2515,30 +3190,36 @@ linear_scan: while (!mark_stack_empty()) { p = pop_mark_stack(); + ASSERT(LOOKS_LIKE_CLOSURE_PTR(p)); info = get_itbl((StgClosure *)p); - ASSERT(p && (LOOKS_LIKE_GHC_INFO(info) || IS_HUGS_CONSTR_INFO(info))); q = p; switch (info->type) { case MVAR: - /* treat MVars specially, because we don't want to evacuate the - * mut_link field in the middle of the closure. - */ { StgMVar *mvar = ((StgMVar *)p); evac_gen = 0; - (StgClosure *)mvar->head = evacuate((StgClosure *)mvar->head); - (StgClosure *)mvar->tail = evacuate((StgClosure *)mvar->tail); - (StgClosure *)mvar->value = evacuate((StgClosure *)mvar->value); + mvar->head = (StgTSO *)evacuate((StgClosure *)mvar->head); + mvar->tail = (StgTSO *)evacuate((StgClosure *)mvar->tail); + mvar->value = evacuate((StgClosure *)mvar->value); evac_gen = saved_evac_gen; - failed_to_evac = rtsFalse; // mutable. + failed_to_evac = rtsTrue; // mutable. break; } case FUN_2_0: + scavenge_fun_srt(info); + ((StgClosure *)p)->payload[1] = evacuate(((StgClosure *)p)->payload[1]); + ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]); + break; + case THUNK_2_0: - scavenge_srt(info); + scavenge_thunk_srt(info); + ((StgThunk *)p)->payload[1] = evacuate(((StgThunk *)p)->payload[1]); + ((StgThunk *)p)->payload[0] = evacuate(((StgThunk *)p)->payload[0]); + break; + case CONSTR_2_0: ((StgClosure *)p)->payload[1] = evacuate(((StgClosure *)p)->payload[1]); ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]); @@ -2546,9 +3227,16 @@ linear_scan: case FUN_1_0: case FUN_1_1: + scavenge_fun_srt(info); + ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]); + break; + case THUNK_1_0: case THUNK_1_1: - scavenge_srt(info); + scavenge_thunk_srt(info); + ((StgThunk *)p)->payload[0] = evacuate(((StgThunk *)p)->payload[0]); + break; + case CONSTR_1_0: case CONSTR_1_1: ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]); @@ -2556,33 +3244,57 @@ linear_scan: case FUN_0_1: case FUN_0_2: + scavenge_fun_srt(info); + break; + case THUNK_0_1: case THUNK_0_2: - scavenge_srt(info); + scavenge_thunk_srt(info); + break; + case CONSTR_0_1: case CONSTR_0_2: break; case FUN: + scavenge_fun_srt(info); + goto gen_obj; + case THUNK: - scavenge_srt(info); - // fall through + { + StgPtr end; + + scavenge_thunk_srt(info); + end = (P_)((StgThunk *)p)->payload + info->layout.payload.ptrs; + for (p = (P_)((StgThunk *)p)->payload; p < end; p++) { + *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); + } + break; + } + gen_obj: case CONSTR: case WEAK: - case FOREIGN: case STABLE_NAME: - case BCO: { StgPtr end; end = (P_)((StgClosure *)p)->payload + info->layout.payload.ptrs; for (p = (P_)((StgClosure *)p)->payload; p < end; p++) { - (StgClosure *)*p = evacuate((StgClosure *)*p); + *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); } break; } + case BCO: { + StgBCO *bco = (StgBCO *)p; + bco->instrs = (StgArrWords *)evacuate((StgClosure *)bco->instrs); + bco->literals = (StgArrWords *)evacuate((StgClosure *)bco->literals); + bco->ptrs = (StgMutArrPtrs *)evacuate((StgClosure *)bco->ptrs); + bco->itbls = (StgArrWords *)evacuate((StgClosure *)bco->itbls); + break; + } + case IND_PERM: // don't need to do anything here: the only possible case // is that we're in a 1-space compacting collector, with @@ -2591,25 +3303,25 @@ linear_scan: case IND_OLDGEN: case IND_OLDGEN_PERM: - ((StgIndOldGen *)p)->indirectee = - evacuate(((StgIndOldGen *)p)->indirectee); - if (failed_to_evac) { - recordOldToNewPtrs((StgMutClosure *)p); - } - failed_to_evac = rtsFalse; + ((StgInd *)p)->indirectee = + evacuate(((StgInd *)p)->indirectee); break; - case MUT_VAR: - evac_gen = 0; + case MUT_VAR_CLEAN: + case MUT_VAR_DIRTY: { + rtsBool saved_eager_promotion = eager_promotion; + + eager_promotion = rtsFalse; ((StgMutVar *)p)->var = evacuate(((StgMutVar *)p)->var); - evac_gen = saved_evac_gen; - failed_to_evac = rtsFalse; - break; - - case MUT_CONS: - // ignore these - failed_to_evac = rtsFalse; + eager_promotion = saved_eager_promotion; + + if (failed_to_evac) { + ((StgClosure *)q)->header.info = &stg_MUT_VAR_DIRTY_info; + } else { + ((StgClosure *)q)->header.info = &stg_MUT_VAR_CLEAN_info; + } break; + } case CAF_BLACKHOLE: case SE_CAF_BLACKHOLE: @@ -2618,15 +3330,6 @@ linear_scan: case ARR_WORDS: break; - case BLACKHOLE_BQ: - { - StgBlockingQueue *bh = (StgBlockingQueue *)p; - (StgClosure *)bh->blocking_queue = - evacuate((StgClosure *)bh->blocking_queue); - failed_to_evac = rtsFalse; - break; - } - case THUNK_SELECTOR: { StgSelector *s = (StgSelector *)p; @@ -2634,42 +3337,70 @@ linear_scan: break; } - case AP_UPD: // same as PAPs - case PAP: - /* Treat a PAP just like a section of stack, not forgetting to - * evacuate the function pointer too... - */ - { - StgPAP* pap = (StgPAP *)p; + // A chunk of stack saved in a heap object + case AP_STACK: + { + StgAP_STACK *ap = (StgAP_STACK *)p; - pap->fun = evacuate(pap->fun); - scavenge_stack((P_)pap->payload, (P_)pap->payload + pap->n_args); + ap->fun = evacuate(ap->fun); + scavenge_stack((StgPtr)ap->payload, (StgPtr)ap->payload + ap->size); break; } + + case PAP: + scavenge_PAP((StgPAP *)p); + break; + + case AP: + scavenge_AP((StgAP *)p); + break; - case MUT_ARR_PTRS: + case MUT_ARR_PTRS_CLEAN: + case MUT_ARR_PTRS_DIRTY: // follow everything { StgPtr next; - - evac_gen = 0; // repeatedly mutable + rtsBool saved_eager; + + // We don't eagerly promote objects pointed to by a mutable + // array, but if we find the array only points to objects in + // the same or an older generation, we mark it "clean" and + // avoid traversing it during minor GCs. + saved_eager = eager_promotion; + eager_promotion = rtsFalse; next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p); for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) { - (StgClosure *)*p = evacuate((StgClosure *)*p); + *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); } - evac_gen = saved_evac_gen; - failed_to_evac = rtsFalse; // mutable anyhow. + eager_promotion = saved_eager; + + if (failed_to_evac) { + ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_DIRTY_info; + } else { + ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_CLEAN_info; + } + + failed_to_evac = rtsTrue; // mutable anyhow. break; } case MUT_ARR_PTRS_FROZEN: + case MUT_ARR_PTRS_FROZEN0: // follow everything { - StgPtr next; + StgPtr next, q = p; next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p); for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) { - (StgClosure *)*p = evacuate((StgClosure *)*p); + *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); + } + + // If we're going to put this object on the mutable list, then + // set its info ptr to MUT_ARR_PTRS_FROZEN0 to indicate that. + if (failed_to_evac) { + ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_FROZEN0_info; + } else { + ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_FROZEN_info; } break; } @@ -2677,15 +3408,24 @@ linear_scan: case TSO: { StgTSO *tso = (StgTSO *)p; - evac_gen = 0; + rtsBool saved_eager = eager_promotion; + + eager_promotion = rtsFalse; scavengeTSO(tso); - evac_gen = saved_evac_gen; - failed_to_evac = rtsFalse; + eager_promotion = saved_eager; + + if (failed_to_evac) { + tso->flags |= TSO_DIRTY; + } else { + tso->flags &= ~TSO_DIRTY; + } + + failed_to_evac = rtsTrue; // always on the mutable list break; } #if defined(PAR) - case RBH: // cf. BLACKHOLE_BQ + case RBH: { #if 0 nat size, ptrs, nonptrs, vhs; @@ -2693,12 +3433,11 @@ linear_scan: StgInfoTable *rip = get_closure_info(p, &size, &ptrs, &nonptrs, &vhs, str); #endif StgRBH *rbh = (StgRBH *)p; - (StgClosure *)rbh->blocking_queue = - evacuate((StgClosure *)rbh->blocking_queue); - recordMutable((StgMutClosure *)rbh); - failed_to_evac = rtsFalse; // mutable anyhow. + bh->blocking_queue = + (StgTSO *)evacuate((StgClosure *)bh->blocking_queue); + failed_to_evac = rtsTrue; // mutable anyhow. IF_DEBUG(gc, - belch("@@ scavenge: RBH %p (%s) (new blocking_queue link=%p)", + debugBelch("@@ scavenge: RBH %p (%s) (new blocking_queue link=%p)", p, info_type(p), (StgClosure *)rbh->blocking_queue)); break; } @@ -2712,12 +3451,8 @@ linear_scan: // follow the link to the rest of the blocking queue (StgClosure *)bf->link = evacuate((StgClosure *)bf->link); - if (failed_to_evac) { - failed_to_evac = rtsFalse; - recordMutable((StgMutClosure *)bf); - } IF_DEBUG(gc, - belch("@@ scavenge: %p (%s); node is now %p; exciting, isn't it", + debugBelch("@@ scavenge: %p (%s); node is now %p; exciting, isn't it", bf, info_type((StgClosure *)bf), bf->node, info_type(bf->node))); break; @@ -2729,21 +3464,68 @@ linear_scan: case FETCH_ME: break; // nothing to do in this case - case FETCH_ME_BQ: // cf. BLACKHOLE_BQ + case FETCH_ME_BQ: { StgFetchMeBlockingQueue *fmbq = (StgFetchMeBlockingQueue *)p; (StgClosure *)fmbq->blocking_queue = evacuate((StgClosure *)fmbq->blocking_queue); - if (failed_to_evac) { - failed_to_evac = rtsFalse; - recordMutable((StgMutClosure *)fmbq); - } IF_DEBUG(gc, - belch("@@ scavenge: %p (%s) exciting, isn't it", + debugBelch("@@ scavenge: %p (%s) exciting, isn't it", p, info_type((StgClosure *)p))); break; } -#endif // PAR +#endif /* PAR */ + + case TVAR_WAIT_QUEUE: + { + StgTVarWaitQueue *wq = ((StgTVarWaitQueue *) p); + evac_gen = 0; + wq->waiting_tso = (StgTSO *)evacuate((StgClosure*)wq->waiting_tso); + wq->next_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)wq->next_queue_entry); + wq->prev_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)wq->prev_queue_entry); + evac_gen = saved_evac_gen; + failed_to_evac = rtsTrue; // mutable + break; + } + + case TVAR: + { + StgTVar *tvar = ((StgTVar *) p); + evac_gen = 0; + tvar->current_value = evacuate((StgClosure*)tvar->current_value); + tvar->first_wait_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)tvar->first_wait_queue_entry); + evac_gen = saved_evac_gen; + failed_to_evac = rtsTrue; // mutable + break; + } + + case TREC_CHUNK: + { + StgWord i; + StgTRecChunk *tc = ((StgTRecChunk *) p); + TRecEntry *e = &(tc -> entries[0]); + evac_gen = 0; + tc->prev_chunk = (StgTRecChunk *)evacuate((StgClosure*)tc->prev_chunk); + for (i = 0; i < tc -> next_entry_idx; i ++, e++ ) { + e->tvar = (StgTVar *)evacuate((StgClosure*)e->tvar); + e->expected_value = evacuate((StgClosure*)e->expected_value); + e->new_value = evacuate((StgClosure*)e->new_value); + } + evac_gen = saved_evac_gen; + failed_to_evac = rtsTrue; // mutable + break; + } + + case TREC_HEADER: + { + StgTRecHeader *trec = ((StgTRecHeader *) p); + evac_gen = 0; + trec->enclosing_trec = (StgTRecHeader *)evacuate((StgClosure*)trec->enclosing_trec); + trec->current_chunk = (StgTRecChunk *)evacuate((StgClosure*)trec->current_chunk); + evac_gen = saved_evac_gen; + failed_to_evac = rtsTrue; // mutable + break; + } default: barf("scavenge_mark_stack: unimplemented/strange closure type %d @ %p", @@ -2752,7 +3534,9 @@ linear_scan: if (failed_to_evac) { failed_to_evac = rtsFalse; - mkMutCons((StgClosure *)q, &generations[evac_gen]); + if (evac_gen > 0) { + recordMutableGen((StgClosure *)q, &generations[evac_gen]); + } } // mark the next bit to indicate "scavenged" @@ -2762,9 +3546,9 @@ linear_scan: // start a new linear scan if the mark stack overflowed at some point if (mark_stack_overflowed && oldgen_scan_bd == NULL) { - IF_DEBUG(gc, belch("scavenge_mark_stack: starting linear scan")); + IF_DEBUG(gc, debugBelch("scavenge_mark_stack: starting linear scan")); mark_stack_overflowed = rtsFalse; - oldgen_scan_bd = oldest_gen->steps[0].blocks; + oldgen_scan_bd = oldest_gen->steps[0].old_blocks; oldgen_scan = oldgen_scan_bd->start; } @@ -2782,12 +3566,12 @@ linear_scan: // already scavenged? if (is_marked(oldgen_scan+1,oldgen_scan_bd)) { - oldgen_scan += sizeofW(StgHeader) + MIN_NONUPD_SIZE; + oldgen_scan += sizeofW(StgHeader) + MIN_PAYLOAD_SIZE; goto loop; } push_mark_stack(oldgen_scan); // ToDo: bump the linear scan by the actual size of the object - oldgen_scan += sizeofW(StgHeader) + MIN_NONUPD_SIZE; + oldgen_scan += sizeofW(StgHeader) + MIN_PAYLOAD_SIZE; goto linear_scan; } @@ -2814,25 +3598,45 @@ scavenge_one(StgPtr p) nat saved_evac_gen = evac_gen; rtsBool no_luck; - ASSERT(p && (LOOKS_LIKE_GHC_INFO(GET_INFO((StgClosure *)p)) - || IS_HUGS_CONSTR_INFO(GET_INFO((StgClosure *)p)))); - + ASSERT(LOOKS_LIKE_CLOSURE_PTR(p)); info = get_itbl((StgClosure *)p); switch (info->type) { - case FUN: - case FUN_1_0: // hardly worth specialising these guys - case FUN_0_1: - case FUN_1_1: - case FUN_0_2: - case FUN_2_0: + case MVAR: + { + StgMVar *mvar = ((StgMVar *)p); + evac_gen = 0; + mvar->head = (StgTSO *)evacuate((StgClosure *)mvar->head); + mvar->tail = (StgTSO *)evacuate((StgClosure *)mvar->tail); + mvar->value = evacuate((StgClosure *)mvar->value); + evac_gen = saved_evac_gen; + failed_to_evac = rtsTrue; // mutable. + break; + } + case THUNK: case THUNK_1_0: case THUNK_0_1: case THUNK_1_1: case THUNK_0_2: case THUNK_2_0: + { + StgPtr q, end; + + end = (StgPtr)((StgThunk *)p)->payload + info->layout.payload.ptrs; + for (q = (StgPtr)((StgThunk *)p)->payload; q < end; q++) { + *q = (StgWord)(StgPtr)evacuate((StgClosure *)*q); + } + break; + } + + case FUN: + case FUN_1_0: // hardly worth specialising these guys + case FUN_0_1: + case FUN_1_1: + case FUN_0_2: + case FUN_2_0: case CONSTR: case CONSTR_1_0: case CONSTR_0_1: @@ -2840,19 +3644,34 @@ scavenge_one(StgPtr p) case CONSTR_0_2: case CONSTR_2_0: case WEAK: - case FOREIGN: case IND_PERM: - case IND_OLDGEN_PERM: { StgPtr q, end; end = (StgPtr)((StgClosure *)p)->payload + info->layout.payload.ptrs; for (q = (StgPtr)((StgClosure *)p)->payload; q < end; q++) { - (StgClosure *)*q = evacuate((StgClosure *)*q); + *q = (StgWord)(StgPtr)evacuate((StgClosure *)*q); } break; } + case MUT_VAR_CLEAN: + case MUT_VAR_DIRTY: { + StgPtr q = p; + rtsBool saved_eager_promotion = eager_promotion; + + eager_promotion = rtsFalse; + ((StgMutVar *)p)->var = evacuate(((StgMutVar *)p)->var); + eager_promotion = saved_eager_promotion; + + if (failed_to_evac) { + ((StgClosure *)q)->header.info = &stg_MUT_VAR_DIRTY_info; + } else { + ((StgClosure *)q)->header.info = &stg_MUT_VAR_CLEAN_info; + } + break; + } + case CAF_BLACKHOLE: case SE_CAF_BLACKHOLE: case SE_BLACKHOLE: @@ -2866,34 +3685,74 @@ scavenge_one(StgPtr p) break; } + case AP_STACK: + { + StgAP_STACK *ap = (StgAP_STACK *)p; + + ap->fun = evacuate(ap->fun); + scavenge_stack((StgPtr)ap->payload, (StgPtr)ap->payload + ap->size); + p = (StgPtr)ap->payload + ap->size; + break; + } + + case PAP: + p = scavenge_PAP((StgPAP *)p); + break; + + case AP: + p = scavenge_AP((StgAP *)p); + break; + case ARR_WORDS: // nothing to follow break; - - case MUT_ARR_PTRS: + + case MUT_ARR_PTRS_CLEAN: + case MUT_ARR_PTRS_DIRTY: { - // follow everything - StgPtr next; - - evac_gen = 0; // repeatedly mutable - recordMutable((StgMutClosure *)p); + StgPtr next, q; + rtsBool saved_eager; + + // We don't eagerly promote objects pointed to by a mutable + // array, but if we find the array only points to objects in + // the same or an older generation, we mark it "clean" and + // avoid traversing it during minor GCs. + saved_eager = eager_promotion; + eager_promotion = rtsFalse; + q = p; next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p); for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) { - (StgClosure *)*p = evacuate((StgClosure *)*p); + *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); } - evac_gen = saved_evac_gen; - failed_to_evac = rtsFalse; + eager_promotion = saved_eager; + + if (failed_to_evac) { + ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_DIRTY_info; + } else { + ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_CLEAN_info; + } + + failed_to_evac = rtsTrue; break; } case MUT_ARR_PTRS_FROZEN: + case MUT_ARR_PTRS_FROZEN0: { // follow everything - StgPtr next; + StgPtr next, q=p; next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p); for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) { - (StgClosure *)*p = evacuate((StgClosure *)*p); + *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); + } + + // If we're going to put this object on the mutable list, then + // set its info ptr to MUT_ARR_PTRS_FROZEN0 to indicate that. + if (failed_to_evac) { + ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_FROZEN0_info; + } else { + ((StgClosure *)q)->header.info = &stg_MUT_ARR_PTRS_FROZEN_info; } break; } @@ -2901,83 +3760,144 @@ scavenge_one(StgPtr p) case TSO: { StgTSO *tso = (StgTSO *)p; - - evac_gen = 0; // repeatedly mutable + rtsBool saved_eager = eager_promotion; + + eager_promotion = rtsFalse; scavengeTSO(tso); - recordMutable((StgMutClosure *)tso); - evac_gen = saved_evac_gen; - failed_to_evac = rtsFalse; + eager_promotion = saved_eager; + + if (failed_to_evac) { + tso->flags |= TSO_DIRTY; + } else { + tso->flags &= ~TSO_DIRTY; + } + + failed_to_evac = rtsTrue; // always on the mutable list break; } - case AP_UPD: - case PAP: +#if defined(PAR) + case RBH: { - StgPAP* pap = (StgPAP *)p; - pap->fun = evacuate(pap->fun); - scavenge_stack((P_)pap->payload, (P_)pap->payload + pap->n_args); +#if 0 + nat size, ptrs, nonptrs, vhs; + char str[80]; + StgInfoTable *rip = get_closure_info(p, &size, &ptrs, &nonptrs, &vhs, str); +#endif + StgRBH *rbh = (StgRBH *)p; + (StgClosure *)rbh->blocking_queue = + evacuate((StgClosure *)rbh->blocking_queue); + failed_to_evac = rtsTrue; // mutable anyhow. + IF_DEBUG(gc, + debugBelch("@@ scavenge: RBH %p (%s) (new blocking_queue link=%p)", + p, info_type(p), (StgClosure *)rbh->blocking_queue)); + // ToDo: use size of reverted closure here! break; } - case IND_OLDGEN: - // This might happen if for instance a MUT_CONS was pointing to a - // THUNK which has since been updated. The IND_OLDGEN will - // be on the mutable list anyway, so we don't need to do anything - // here. + case BLOCKED_FETCH: + { + StgBlockedFetch *bf = (StgBlockedFetch *)p; + // follow the pointer to the node which is being demanded + (StgClosure *)bf->node = + evacuate((StgClosure *)bf->node); + // follow the link to the rest of the blocking queue + (StgClosure *)bf->link = + evacuate((StgClosure *)bf->link); + IF_DEBUG(gc, + debugBelch("@@ scavenge: %p (%s); node is now %p; exciting, isn't it", + bf, info_type((StgClosure *)bf), + bf->node, info_type(bf->node))); break; + } - default: - barf("scavenge_one: strange object %d", (int)(info->type)); - } - - no_luck = failed_to_evac; - failed_to_evac = rtsFalse; - return (no_luck); -} - -/* ----------------------------------------------------------------------------- - Scavenging mutable lists. +#ifdef DIST + case REMOTE_REF: +#endif + case FETCH_ME: + break; // nothing to do in this case - 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. - -------------------------------------------------------------------------- */ + case FETCH_ME_BQ: + { + StgFetchMeBlockingQueue *fmbq = (StgFetchMeBlockingQueue *)p; + (StgClosure *)fmbq->blocking_queue = + evacuate((StgClosure *)fmbq->blocking_queue); + IF_DEBUG(gc, + debugBelch("@@ scavenge: %p (%s) exciting, isn't it", + p, info_type((StgClosure *)p))); + break; + } +#endif -static void -scavenge_mut_once_list(generation *gen) -{ - const StgInfoTable *info; - StgMutClosure *p, *next, *new_list; + case TVAR_WAIT_QUEUE: + { + StgTVarWaitQueue *wq = ((StgTVarWaitQueue *) p); + evac_gen = 0; + wq->waiting_tso = (StgTSO *)evacuate((StgClosure*)wq->waiting_tso); + wq->next_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)wq->next_queue_entry); + wq->prev_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)wq->prev_queue_entry); + evac_gen = saved_evac_gen; + failed_to_evac = rtsTrue; // mutable + break; + } - p = gen->mut_once_list; - new_list = END_MUT_LIST; - next = p->mut_link; + case TVAR: + { + StgTVar *tvar = ((StgTVar *) p); + evac_gen = 0; + tvar->current_value = evacuate((StgClosure*)tvar->current_value); + tvar->first_wait_queue_entry = (StgTVarWaitQueue *)evacuate((StgClosure*)tvar->first_wait_queue_entry); + evac_gen = saved_evac_gen; + failed_to_evac = rtsTrue; // mutable + break; + } - evac_gen = gen->no; - failed_to_evac = rtsFalse; + case TREC_HEADER: + { + StgTRecHeader *trec = ((StgTRecHeader *) p); + evac_gen = 0; + trec->enclosing_trec = (StgTRecHeader *)evacuate((StgClosure*)trec->enclosing_trec); + trec->current_chunk = (StgTRecChunk *)evacuate((StgClosure*)trec->current_chunk); + evac_gen = saved_evac_gen; + failed_to_evac = rtsTrue; // mutable + break; + } - for (; p != END_MUT_LIST; p = next, next = p->mut_link) { + case TREC_CHUNK: + { + StgWord i; + StgTRecChunk *tc = ((StgTRecChunk *) p); + TRecEntry *e = &(tc -> entries[0]); + evac_gen = 0; + tc->prev_chunk = (StgTRecChunk *)evacuate((StgClosure*)tc->prev_chunk); + for (i = 0; i < tc -> next_entry_idx; i ++, e++ ) { + e->tvar = (StgTVar *)evacuate((StgClosure*)e->tvar); + e->expected_value = evacuate((StgClosure*)e->expected_value); + e->new_value = evacuate((StgClosure*)e->new_value); + } + evac_gen = saved_evac_gen; + failed_to_evac = rtsTrue; // mutable + break; + } - // make sure the info pointer is into text space - ASSERT(p && (LOOKS_LIKE_GHC_INFO(GET_INFO(p)) - || IS_HUGS_CONSTR_INFO(GET_INFO(p)))); - - info = get_itbl(p); - /* - if (info->type==RBH) - info = REVERT_INFOPTR(info); // if it's an RBH, look at the orig closure - */ - switch(info->type) { - case IND_OLDGEN: case IND_OLDGEN_PERM: case IND_STATIC: - /* Try to pull the indirectee into this generation, so we can - * remove the indirection from the mutable list. - */ - ((StgIndOldGen *)p)->indirectee = - evacuate(((StgIndOldGen *)p)->indirectee); - + { + /* Careful here: a THUNK can be on the mutable list because + * it contains pointers to young gen objects. If such a thunk + * is updated, the IND_OLDGEN will be added to the mutable + * list again, and we'll scavenge it twice. evacuate() + * doesn't check whether the object has already been + * evacuated, so we perform that check here. + */ + StgClosure *q = ((StgInd *)p)->indirectee; + if (HEAP_ALLOCED(q) && Bdescr((StgPtr)q)->flags & BF_EVACUATED) { + break; + } + ((StgInd *)p)->indirectee = evacuate(q); + } + #if 0 && defined(DEBUG) if (RtsFlags.DebugFlags.gc) /* Debugging code to print out the size of the thing we just @@ -3000,240 +3920,98 @@ scavenge_mut_once_list(generation *gen) } else { size = gen->steps[0].scan - start; } - belch("evac IND_OLDGEN: %ld bytes", size * sizeof(W_)); + debugBelch("evac IND_OLDGEN: %ld bytes", size * sizeof(W_)); } #endif - - /* failed_to_evac might happen if we've got more than two - * generations, we're collecting only generation 0, the - * indirection resides in generation 2 and the indirectee is - * in generation 1. - */ - if (failed_to_evac) { - failed_to_evac = rtsFalse; - p->mut_link = new_list; - new_list = p; - } else { - /* the mut_link field of an IND_STATIC is overloaded as the - * static link field too (it just so happens that we don't need - * both at the same time), so we need to NULL it out when - * removing this object from the mutable list because the static - * link fields are all assumed to be NULL before doing a major - * collection. - */ - p->mut_link = NULL; - } - continue; - - case MUT_CONS: - /* MUT_CONS is a kind of MUT_VAR, except it that we try to remove - * it from the mutable list if possible by promoting whatever it - * points to. - */ - if (scavenge_one((StgPtr)((StgMutVar *)p)->var)) { - /* didn't manage to promote everything, so put the - * MUT_CONS back on the list. - */ - p->mut_link = new_list; - new_list = p; - } - continue; + break; default: - // shouldn't have anything else on the mutables list - barf("scavenge_mut_once_list: strange object? %d", (int)(info->type)); - } - } + barf("scavenge_one: strange object %d", (int)(info->type)); + } - gen->mut_once_list = new_list; + no_luck = failed_to_evac; + failed_to_evac = rtsFalse; + return (no_luck); } +/* ----------------------------------------------------------------------------- + Scavenging mutable lists. + + We treat the mutable list of each generation > N (i.e. all the + generations older than the one being collected) as roots. We also + remove non-mutable objects from the mutable list at this point. + -------------------------------------------------------------------------- */ static void scavenge_mutable_list(generation *gen) { - const StgInfoTable *info; - StgMutClosure *p, *next; - - p = gen->saved_mut_list; - next = p->mut_link; - - evac_gen = 0; - failed_to_evac = rtsFalse; - - for (; p != END_MUT_LIST; p = next, next = p->mut_link) { - - // make sure the info pointer is into text space - ASSERT(p && (LOOKS_LIKE_GHC_INFO(GET_INFO(p)) - || IS_HUGS_CONSTR_INFO(GET_INFO(p)))); - - info = get_itbl(p); - /* - if (info->type==RBH) - info = REVERT_INFOPTR(info); // if it's an RBH, look at the orig closure - */ - switch(info->type) { - - case MUT_ARR_PTRS: - // follow everything - p->mut_link = gen->mut_list; - gen->mut_list = p; - { - StgPtr end, q; - - end = (P_)p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p); - for (q = (P_)((StgMutArrPtrs *)p)->payload; q < end; q++) { - (StgClosure *)*q = evacuate((StgClosure *)*q); - } - continue; - } - - // Happens if a MUT_ARR_PTRS in the old generation is frozen - case MUT_ARR_PTRS_FROZEN: - { - StgPtr end, q; - - evac_gen = gen->no; - end = (P_)p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p); - for (q = (P_)((StgMutArrPtrs *)p)->payload; q < end; q++) { - (StgClosure *)*q = evacuate((StgClosure *)*q); - } - evac_gen = 0; - p->mut_link = NULL; - if (failed_to_evac) { - failed_to_evac = rtsFalse; - mkMutCons((StgClosure *)p, gen); - } - continue; - } - - case MUT_VAR: - ((StgMutVar *)p)->var = evacuate(((StgMutVar *)p)->var); - p->mut_link = gen->mut_list; - gen->mut_list = p; - continue; - - case MVAR: - { - StgMVar *mvar = (StgMVar *)p; - (StgClosure *)mvar->head = evacuate((StgClosure *)mvar->head); - (StgClosure *)mvar->tail = evacuate((StgClosure *)mvar->tail); - (StgClosure *)mvar->value = evacuate((StgClosure *)mvar->value); - p->mut_link = gen->mut_list; - gen->mut_list = p; - continue; - } - - case TSO: - { - StgTSO *tso = (StgTSO *)p; - - scavengeTSO(tso); - - /* Don't take this TSO off the mutable list - it might still - * point to some younger objects (because we set evac_gen to 0 - * above). - */ - tso->mut_link = gen->mut_list; - gen->mut_list = (StgMutClosure *)tso; - continue; - } - - case BLACKHOLE_BQ: - { - StgBlockingQueue *bh = (StgBlockingQueue *)p; - (StgClosure *)bh->blocking_queue = - evacuate((StgClosure *)bh->blocking_queue); - p->mut_link = gen->mut_list; - gen->mut_list = p; - continue; - } - - /* Happens if a BLACKHOLE_BQ in the old generation is updated: - */ - case IND_OLDGEN: - case IND_OLDGEN_PERM: - /* Try to pull the indirectee into this generation, so we can - * remove the indirection from the mutable list. - */ - evac_gen = gen->no; - ((StgIndOldGen *)p)->indirectee = - evacuate(((StgIndOldGen *)p)->indirectee); - evac_gen = 0; - - if (failed_to_evac) { - failed_to_evac = rtsFalse; - p->mut_link = gen->mut_once_list; - gen->mut_once_list = p; - } else { - p->mut_link = NULL; - } - continue; - -#if defined(PAR) - // HWL: check whether all of these are necessary - - case RBH: // cf. BLACKHOLE_BQ - { - // nat size, ptrs, nonptrs, vhs; - // char str[80]; - // StgInfoTable *rip = get_closure_info(p, &size, &ptrs, &nonptrs, &vhs, str); - StgRBH *rbh = (StgRBH *)p; - (StgClosure *)rbh->blocking_queue = - evacuate((StgClosure *)rbh->blocking_queue); - if (failed_to_evac) { - failed_to_evac = rtsFalse; - recordMutable((StgMutClosure *)rbh); - } - // ToDo: use size of reverted closure here! - p += BLACKHOLE_sizeW(); - break; - } - - case BLOCKED_FETCH: - { - StgBlockedFetch *bf = (StgBlockedFetch *)p; - // follow the pointer to the node which is being demanded - (StgClosure *)bf->node = - evacuate((StgClosure *)bf->node); - // follow the link to the rest of the blocking queue - (StgClosure *)bf->link = - evacuate((StgClosure *)bf->link); - if (failed_to_evac) { - failed_to_evac = rtsFalse; - recordMutable((StgMutClosure *)bf); - } - p += sizeofW(StgBlockedFetch); - break; - } + bdescr *bd; + StgPtr p, q; -#ifdef DIST - case REMOTE_REF: - barf("scavenge_mutable_list: REMOTE_REF %d", (int)(info->type)); + bd = gen->saved_mut_list; + + evac_gen = gen->no; + for (; bd != NULL; bd = bd->link) { + for (q = bd->start; q < bd->free; q++) { + p = (StgPtr)*q; + ASSERT(LOOKS_LIKE_CLOSURE_PTR(p)); + +#ifdef DEBUG + switch (get_itbl((StgClosure *)p)->type) { + case MUT_VAR_CLEAN: + barf("MUT_VAR_CLEAN on mutable list"); + case MUT_VAR_DIRTY: + mutlist_MUTVARS++; break; + case MUT_ARR_PTRS_CLEAN: + case MUT_ARR_PTRS_DIRTY: + case MUT_ARR_PTRS_FROZEN: + case MUT_ARR_PTRS_FROZEN0: + mutlist_MUTARRS++; break; + default: + mutlist_OTHERS++; break; + } #endif - case FETCH_ME: - p += sizeofW(StgFetchMe); - break; // nothing to do in this case - case FETCH_ME_BQ: // cf. BLACKHOLE_BQ - { - StgFetchMeBlockingQueue *fmbq = (StgFetchMeBlockingQueue *)p; - (StgClosure *)fmbq->blocking_queue = - evacuate((StgClosure *)fmbq->blocking_queue); - if (failed_to_evac) { - failed_to_evac = rtsFalse; - recordMutable((StgMutClosure *)fmbq); - } - p += sizeofW(StgFetchMeBlockingQueue); - break; - } -#endif + // Check whether this object is "clean", that is it + // definitely doesn't point into a young generation. + // Clean objects don't need to be scavenged. Some clean + // objects (MUT_VAR_CLEAN) are not kept on the mutable + // list at all; others, such as MUT_ARR_PTRS_CLEAN and + // TSO, are always on the mutable list. + // + switch (get_itbl((StgClosure *)p)->type) { + case MUT_ARR_PTRS_CLEAN: + recordMutableGen((StgClosure *)p,gen); + continue; + case TSO: { + StgTSO *tso = (StgTSO *)p; + if ((tso->flags & TSO_DIRTY) == 0) { + // A clean TSO: we don't have to traverse its + // stack. However, we *do* follow the link field: + // we don't want to have to mark a TSO dirty just + // because we put it on a different queue. + if (tso->why_blocked != BlockedOnBlackHole) { + tso->link = (StgTSO *)evacuate((StgClosure *)tso->link); + } + recordMutableGen((StgClosure *)p,gen); + continue; + } + } + default: + ; + } - default: - // shouldn't have anything else on the mutables list - barf("scavenge_mutable_list: strange object? %d", (int)(info->type)); + if (scavenge_one(p)) { + // didn't manage to promote everything, so put the + // object back on the list. + recordMutableGen((StgClosure *)p,gen); + } + } } - } + + // free the old mut_list + freeChain(gen->saved_mut_list); + gen->saved_mut_list = NULL; } @@ -3251,20 +4029,19 @@ scavenge_static(void) list... */ while (p != END_OF_STATIC_LIST) { + ASSERT(LOOKS_LIKE_CLOSURE_PTR(p)); info = get_itbl(p); /* if (info->type==RBH) info = REVERT_INFOPTR(info); // if it's an RBH, look at the orig closure */ // make sure the info pointer is into text space - ASSERT(p && (LOOKS_LIKE_GHC_INFO(GET_INFO(p)) - || IS_HUGS_CONSTR_INFO(GET_INFO(p)))); /* Take this object *off* the static_objects list, * and put it on the scavenged_static_objects list. */ - static_objects = STATIC_LINK(info,p); - STATIC_LINK(info,p) = scavenged_static_objects; + static_objects = *STATIC_LINK(info,p); + *STATIC_LINK(info,p) = scavenged_static_objects; scavenged_static_objects = p; switch (info -> type) { @@ -3275,22 +4052,23 @@ scavenge_static(void) ind->indirectee = evacuate(ind->indirectee); /* might fail to evacuate it, in which case we have to pop it - * back on the mutable list (and take it off the - * scavenged_static list because the static link and mut link - * pointers are one and the same). + * back on the mutable list of the oldest generation. We + * leave it *on* the scavenged_static_objects list, though, + * in case we visit this object again. */ if (failed_to_evac) { failed_to_evac = rtsFalse; - scavenged_static_objects = IND_STATIC_LINK(p); - ((StgMutClosure *)ind)->mut_link = oldest_gen->mut_once_list; - oldest_gen->mut_once_list = (StgMutClosure *)ind; + recordMutableGen((StgClosure *)p,oldest_gen); } break; } case THUNK_STATIC: + scavenge_thunk_srt(info); + break; + case FUN_STATIC: - scavenge_srt(info); + scavenge_fun_srt(info); break; case CONSTR_STATIC: @@ -3300,7 +4078,7 @@ scavenge_static(void) next = (P_)p->payload + info->layout.payload.ptrs; // evacuate the pointers for (q = (P_)p->payload; q < next; q++) { - (StgClosure *)*q = evacuate((StgClosure *)*q); + *q = (StgWord)(StgPtr)evacuate((StgClosure *)*q); } break; } @@ -3320,200 +4098,193 @@ scavenge_static(void) } /* ----------------------------------------------------------------------------- - scavenge_stack walks over a section of stack and evacuates all the - objects pointed to by it. We can use the same code for walking - PAPs, since these are just sections of copied stack. + scavenge a chunk of memory described by a bitmap -------------------------------------------------------------------------- */ static void -scavenge_stack(StgPtr p, StgPtr stack_end) +scavenge_large_bitmap( StgPtr p, StgLargeBitmap *large_bitmap, nat size ) { - StgPtr q; - const StgInfoTable* info; - StgWord bitmap; - - //IF_DEBUG(sanity, belch(" scavenging stack between %p and %p", p, stack_end)); - - /* - * Each time around this loop, we are looking at a chunk of stack - * that starts with either a pending argument section or an - * activation record. - */ - - while (p < stack_end) { - q = *(P_ *)p; - - // If we've got a tag, skip over that many words on the stack - if (IS_ARG_TAG((W_)q)) { - p += ARG_SIZE(q); - p++; continue; + 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; + } } - - /* Is q a pointer to a closure? - */ - if (! LOOKS_LIKE_GHC_INFO(q) ) { -#ifdef DEBUG - if ( 0 && LOOKS_LIKE_STATIC_CLOSURE(q) ) { // Is it a static closure? - ASSERT(closure_STATIC((StgClosure *)q)); - } - // otherwise, must be a pointer into the allocation space. -#endif +} - (StgClosure *)*p = evacuate((StgClosure *)q); - p++; - continue; +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--; } - - /* - * Otherwise, q must be the info pointer of an activation - * record. All activation records have 'bitmap' style layout - * info. - */ - info = get_itbl((StgClosure *)p); - - switch (info->type) { - - // Dynamic bitmap: the mask is stored on the stack - case RET_DYN: - bitmap = ((StgRetDyn *)p)->liveness; - p = (P_)&((StgRetDyn *)p)->payload[0]; - goto small_bitmap; - - // probably a slow-entry point return address: - case FUN: - case FUN_STATIC: - { -#if 0 - StgPtr old_p = p; - p++; p++; - IF_DEBUG(sanity, - belch("HWL: scavenge_stack: FUN(_STATIC) adjusting p from %p to %p (instead of %p)", - old_p, p, old_p+1)); -#else - p++; // what if FHS!=1 !? -- HWL -#endif - goto follow_srt; - } - - /* Specialised code for update frames, since they're so common. - * We *know* the updatee points to a BLACKHOLE, CAF_BLACKHOLE, - * or BLACKHOLE_BQ, so just inline the code to evacuate it here. - */ - case UPDATE_FRAME: - { - StgUpdateFrame *frame = (StgUpdateFrame *)p; + return p; +} - p += sizeofW(StgUpdateFrame); +/* ----------------------------------------------------------------------------- + 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. + -------------------------------------------------------------------------- */ -#ifndef not_yet - frame->updatee = evacuate(frame->updatee); - continue; -#else // specialised code for update frames, not sure if it's worth it. - StgClosure *to; - nat type = get_itbl(frame->updatee)->type; - if (type == EVACUATED) { - frame->updatee = evacuate(frame->updatee); - continue; - } else { - bdescr *bd = Bdescr((P_)frame->updatee); - step *stp; - if (bd->gen_no > N) { - if (bd->gen_no < evac_gen) { - failed_to_evac = rtsTrue; - } - continue; - } +static void +scavenge_stack(StgPtr p, StgPtr stack_end) +{ + const StgRetInfoTable* info; + StgWord bitmap; + nat size; - // Don't promote blackholes - stp = bd->step; - if (!(stp->gen_no == 0 && - stp->no != 0 && - stp->no == stp->gen->n_steps-1)) { - stp = stp->to; - } + //IF_DEBUG(sanity, debugBelch(" scavenging stack between %p and %p", p, stack_end)); - switch (type) { - case BLACKHOLE: - case CAF_BLACKHOLE: - to = copyPart(frame->updatee, BLACKHOLE_sizeW(), - sizeofW(StgHeader), stp); - frame->updatee = to; - continue; - case BLACKHOLE_BQ: - to = copy(frame->updatee, BLACKHOLE_sizeW(), stp); - frame->updatee = to; - recordMutable((StgMutClosure *)to); - continue; - default: - /* will never be SE_{,CAF_}BLACKHOLE, since we - don't push an update frame for single-entry thunks. KSW 1999-01. */ - barf("scavenge_stack: UPDATE_FRAME updatee"); - } + /* + * 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; } -#endif - } + ((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 SEQ_FRAME: - case RET_BCO: case RET_SMALL: case RET_VEC_SMALL: - bitmap = info->layout.bitmap; - p++; - // this assumes that the payload starts immediately after the info-ptr - small_bitmap: - while (bitmap != 0) { - if ((bitmap & 1) == 0) { - (StgClosure *)*p = evacuate((StgClosure *)*p); - } + bitmap = BITMAP_BITS(info->i.layout.bitmap); + size = BITMAP_SIZE(info->i.layout.bitmap); + // NOTE: the payload starts immediately after the info-ptr, we + // don't have an StgHeader in the same sense as a heap closure. p++; - bitmap = bitmap >> 1; - } - + p = scavenge_small_bitmap(p, size, bitmap); + follow_srt: - scavenge_srt(info); - continue; + if (major_gc) + scavenge_srt((StgClosure **)GET_SRT(info), info->i.srt_bitmap); + continue; + + case RET_BCO: { + StgBCO *bco; + nat size; + + p++; + *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); + bco = (StgBCO *)*p; + p++; + size = BCO_BITMAP_SIZE(bco); + scavenge_large_bitmap(p, BCO_BITMAP(bco), size); + p += size; + continue; + } // large bitmap (> 32 entries, or > 64 on a 64-bit machine) case RET_BIG: case RET_VEC_BIG: - { - StgPtr q; - StgLargeBitmap *large_bitmap; - nat i; + { + nat size; - large_bitmap = info->layout.large_bitmap; + size = GET_LARGE_BITMAP(&info->i)->size; p++; + scavenge_large_bitmap(p, GET_LARGE_BITMAP(&info->i), size); + p += size; + // and don't forget to follow the SRT + goto follow_srt; + } - for (i=0; isize; i++) { - bitmap = large_bitmap->bitmap[i]; - q = p + BITS_IN(W_); - while (bitmap != 0) { - if ((bitmap & 1) == 0) { - (StgClosure *)*p = evacuate((StgClosure *)*p); - } + // Dynamic bitmap: the mask is stored on the stack, and + // there are a number of non-pointers followed by a number + // of pointers above the bitmapped area. (see StgMacros.h, + // HEAP_CHK_GEN). + case RET_DYN: + { + StgWord dyn; + dyn = ((StgRetDyn *)p)->liveness; + + // traverse the bitmap first + bitmap = RET_DYN_LIVENESS(dyn); + p = (P_)&((StgRetDyn *)p)->payload[0]; + size = RET_DYN_BITMAP_SIZE; + p = scavenge_small_bitmap(p, size, bitmap); + + // skip over the non-ptr words + p += RET_DYN_NONPTRS(dyn) + RET_DYN_NONPTR_REGS_SIZE; + + // follow the ptr words + for (size = RET_DYN_PTRS(dyn); size > 0; size--) { + *p = (StgWord)(StgPtr)evacuate((StgClosure *)*p); p++; - bitmap = bitmap >> 1; - } - if (i+1 < large_bitmap->size) { - while (p < q) { - (StgClosure *)*p = evacuate((StgClosure *)*p); - p++; - } - } } + continue; + } - // and don't forget to follow the SRT + case RET_FUN: + { + StgRetFun *ret_fun = (StgRetFun *)p; + StgFunInfoTable *fun_info; + + ret_fun->fun = evacuate(ret_fun->fun); + fun_info = get_fun_itbl(ret_fun->fun); + p = scavenge_arg_block(fun_info, ret_fun->payload); goto follow_srt; - } + } default: - barf("scavenge_stack: weird activation record found on stack: %d", (int)(info->type)); + barf("scavenge_stack: weird activation record found on stack: %d", (int)(info->i.type)); } - } + } } /*----------------------------------------------------------------------------- @@ -3548,7 +4319,9 @@ scavenge_large(step *stp) p = bd->start; if (scavenge_one(p)) { - mkMutCons((StgClosure *)p, stp->gen); + if (stp->gen_no > 0) { + recordMutableGen((StgClosure *)p, stp->gen); + } } } } @@ -3566,28 +4339,8 @@ zero_static_object_list(StgClosure* first_static) for (p = first_static; p != END_OF_STATIC_LIST; p = link) { info = get_itbl(p); - link = STATIC_LINK(info, p); - STATIC_LINK(info,p) = NULL; - } -} - -/* This function is only needed because we share the mutable link - * field with the static link field in an IND_STATIC, so we have to - * zero the mut_link field before doing a major GC, which needs the - * static link field. - * - * It doesn't do any harm to zero all the mutable link fields on the - * mutable list. - */ - -static void -zero_mutable_list( StgMutClosure *first ) -{ - StgMutClosure *next, *c; - - for (c = first; c != END_MUT_LIST; c = next) { - next = c->mut_link; - c->mut_link = NULL; + link = *STATIC_LINK(info, p); + *STATIC_LINK(info,p) = NULL; } } @@ -3600,14 +4353,14 @@ revertCAFs( void ) { StgIndStatic *c; - for (c = (StgIndStatic *)caf_list; c != NULL; + for (c = (StgIndStatic *)revertible_caf_list; c != NULL; c = (StgIndStatic *)c->static_link) { - c->header.info = c->saved_info; + SET_INFO(c, c->saved_info); c->saved_info = NULL; // could, but not necessary: c->static_link = NULL; } - caf_list = NULL; + revertible_caf_list = NULL; } void @@ -3620,6 +4373,11 @@ markCAFs( evac_fn evac ) { evac(&c->indirectee); } + for (c = (StgIndStatic *)revertible_caf_list; c != NULL; + c = (StgIndStatic *)c->static_link) + { + evac(&c->indirectee); + } } /* ----------------------------------------------------------------------------- @@ -3655,7 +4413,7 @@ gcCAFs(void) ASSERT(info->type == IND_STATIC); if (STATIC_LINK(info,p) == NULL) { - IF_DEBUG(gccafs, belch("CAF gc'd at 0x%04lx", (long)p)); + IF_DEBUG(gccafs, debugBelch("CAF gc'd at 0x%04lx", (long)p)); // black hole it SET_INFO(p,&stg_BLACKHOLE_info); p = STATIC_LINK2(info,p); @@ -3669,378 +4427,273 @@ gcCAFs(void) } - // belch("%d CAFs live", i); + // debugBelch("%d CAFs live", i); } #endif /* ----------------------------------------------------------------------------- - Lazy black holing. + * Stack squeezing + * + * Code largely pinched from old RTS, then hacked to bits. We also do + * lazy black holing here. + * + * -------------------------------------------------------------------------- */ - Whenever a thread returns to the scheduler after possibly doing - some work, we have to run down the stack and black-hole all the - closures referred to by update frames. - -------------------------------------------------------------------------- */ +struct stack_gap { StgWord gap_size; struct stack_gap *next_gap; }; static void -threadLazyBlackHole(StgTSO *tso) +stackSqueeze(StgTSO *tso, StgPtr bottom) { - StgUpdateFrame *update_frame; - StgBlockingQueue *bh; - StgPtr stack_end; + StgPtr frame; + rtsBool prev_was_update_frame; + StgClosure *updatee = NULL; + StgRetInfoTable *info; + StgWord current_gap_size; + struct stack_gap *gap; + + // Stage 1: + // Traverse the stack upwards, replacing adjacent update frames + // with a single update frame and a "stack gap". A stack gap + // contains two values: the size of the gap, and the distance + // to the next gap (or the stack top). + + frame = tso->sp; + + ASSERT(frame < bottom); + + prev_was_update_frame = rtsFalse; + current_gap_size = 0; + gap = (struct stack_gap *) (tso->sp - sizeofW(StgUpdateFrame)); - stack_end = &tso->stack[tso->stack_size]; - update_frame = tso->su; + while (frame < bottom) { + + info = get_ret_itbl((StgClosure *)frame); + switch (info->i.type) { - while (1) { - switch (get_itbl(update_frame)->type) { + case UPDATE_FRAME: + { + StgUpdateFrame *upd = (StgUpdateFrame *)frame; + + if (prev_was_update_frame) { + + TICK_UPD_SQUEEZED(); + /* wasn't there something about update squeezing and ticky to be + * sorted out? oh yes: we aren't counting each enter properly + * in this case. See the log somewhere. KSW 1999-04-21 + * + * Check two things: that the two update frames don't point to + * the same object, and that the updatee_bypass isn't already an + * indirection. Both of these cases only happen when we're in a + * block hole-style loop (and there are multiple update frames + * on the stack pointing to the same closure), but they can both + * screw us up if we don't check. + */ + if (upd->updatee != updatee && !closure_IND(upd->updatee)) { + UPD_IND_NOLOCK(upd->updatee, updatee); + } - case CATCH_FRAME: - update_frame = ((StgCatchFrame *)update_frame)->link; - break; + // now mark this update frame as a stack gap. The gap + // marker resides in the bottom-most update frame of + // the series of adjacent frames, and covers all the + // frames in this series. + current_gap_size += sizeofW(StgUpdateFrame); + ((struct stack_gap *)frame)->gap_size = current_gap_size; + ((struct stack_gap *)frame)->next_gap = gap; + + frame += sizeofW(StgUpdateFrame); + continue; + } + + // single update frame, or the topmost update frame in a series + else { + prev_was_update_frame = rtsTrue; + updatee = upd->updatee; + frame += sizeofW(StgUpdateFrame); + continue; + } + } + + default: + prev_was_update_frame = rtsFalse; - case UPDATE_FRAME: - bh = (StgBlockingQueue *)update_frame->updatee; + // we're not in a gap... check whether this is the end of a gap + // (an update frame can't be the end of a gap). + if (current_gap_size != 0) { + gap = (struct stack_gap *) (frame - sizeofW(StgUpdateFrame)); + } + current_gap_size = 0; - /* if the thunk is already blackholed, it means we've also - * already blackholed the rest of the thunks on this stack, - * so we can stop early. - * - * The blackhole made for a CAF is a CAF_BLACKHOLE, so they - * don't interfere with this optimisation. - */ - if (bh->header.info == &stg_BLACKHOLE_info) { - return; - } + frame += stack_frame_sizeW((StgClosure *)frame); + continue; + } + } - if (bh->header.info != &stg_BLACKHOLE_BQ_info && - bh->header.info != &stg_CAF_BLACKHOLE_info) { -#if (!defined(LAZY_BLACKHOLING)) && defined(DEBUG) - belch("Unexpected lazy BHing required at 0x%04x",(int)bh); -#endif -#ifdef PROFILING - // @LDV profiling - // We pretend that bh is now dead. - LDV_recordDead_FILL_SLOP_DYNAMIC((StgClosure *)bh); -#endif - SET_INFO(bh,&stg_BLACKHOLE_info); -#ifdef PROFILING - // @LDV profiling - // We pretend that bh has just been created. - LDV_recordCreate(bh); -#endif - } + if (current_gap_size != 0) { + gap = (struct stack_gap *) (frame - sizeofW(StgUpdateFrame)); + } - update_frame = update_frame->link; - break; + // Now we have a stack with gaps in it, and we have to walk down + // shoving the stack up to fill in the gaps. A diagram might + // help: + // + // +| ********* | + // | ********* | <- sp + // | | + // | | <- gap_start + // | ......... | | + // | stack_gap | <- gap | chunk_size + // | ......... | | + // | ......... | <- gap_end v + // | ********* | + // | ********* | + // | ********* | + // -| ********* | + // + // 'sp' points the the current top-of-stack + // 'gap' points to the stack_gap structure inside the gap + // ***** indicates real stack data + // ..... indicates gap + // indicates unused + // + { + void *sp; + void *gap_start, *next_gap_start, *gap_end; + nat chunk_size; - case SEQ_FRAME: - update_frame = ((StgSeqFrame *)update_frame)->link; - break; + next_gap_start = (void *)((unsigned char*)gap + sizeof(StgUpdateFrame)); + sp = next_gap_start; - case STOP_FRAME: - return; - default: - barf("threadPaused"); - } - } -} + while ((StgPtr)gap > tso->sp) { + + // we're working in *bytes* now... + gap_start = next_gap_start; + gap_end = (void*) ((unsigned char*)gap_start - gap->gap_size * sizeof(W_)); + gap = gap->next_gap; + next_gap_start = (void *)((unsigned char*)gap + sizeof(StgUpdateFrame)); + + chunk_size = (unsigned char*)gap_end - (unsigned char*)next_gap_start; + sp -= chunk_size; + memmove(sp, next_gap_start, chunk_size); + } + + tso->sp = (StgPtr)sp; + } +} /* ----------------------------------------------------------------------------- - * Stack squeezing - * - * Code largely pinched from old RTS, then hacked to bits. We also do - * lazy black holing here. - * + * Pausing a thread + * + * We have to prepare for GC - this means doing lazy black holing + * here. We also take the opportunity to do stack squeezing if it's + * turned on. * -------------------------------------------------------------------------- */ - -static void -threadSqueezeStack(StgTSO *tso) +void +threadPaused(Capability *cap, StgTSO *tso) { - lnat displacement = 0; - StgUpdateFrame *frame; - StgUpdateFrame *next_frame; // Temporally next - StgUpdateFrame *prev_frame; // Temporally previous - StgPtr bottom; - rtsBool prev_was_update_frame; -#if DEBUG - StgUpdateFrame *top_frame; - nat upd_frames=0, stop_frames=0, catch_frames=0, seq_frames=0, - bhs=0, squeezes=0; - void printObj( StgClosure *obj ); // from Printer.c - - top_frame = tso->su; -#endif - - bottom = &(tso->stack[tso->stack_size]); - frame = tso->su; + StgClosure *frame; + StgRetInfoTable *info; + StgClosure *bh; + StgPtr stack_end; + nat words_to_squeeze = 0; + nat weight = 0; + nat weight_pending = 0; + rtsBool prev_was_update_frame; + + stack_end = &tso->stack[tso->stack_size]; + + frame = (StgClosure *)tso->sp; - /* There must be at least one frame, namely the STOP_FRAME. - */ - ASSERT((P_)frame < bottom); + while (1) { + // If we've already marked this frame, then stop here. + if (frame->header.info == (StgInfoTable *)&stg_marked_upd_frame_info) { + goto end; + } - /* Walk down the stack, reversing the links between frames so that - * we can walk back up as we squeeze from the bottom. Note that - * next_frame and prev_frame refer to next and previous as they were - * added to the stack, rather than the way we see them in this - * walk. (It makes the next loop less confusing.) - * - * Stop if we find an update frame pointing to a black hole - * (see comment in threadLazyBlackHole()). - */ - - next_frame = NULL; - // bottom - sizeof(StgStopFrame) is the STOP_FRAME - while ((P_)frame < bottom - sizeofW(StgStopFrame)) { - prev_frame = frame->link; - frame->link = next_frame; - next_frame = frame; - frame = prev_frame; -#if DEBUG - IF_DEBUG(sanity, - if (!(frame>=top_frame && frame<=(StgUpdateFrame *)bottom)) { - printObj((StgClosure *)prev_frame); - barf("threadSqueezeStack: current frame is rubbish %p; previous was %p\n", - frame, prev_frame); - }) - switch (get_itbl(frame)->type) { - case UPDATE_FRAME: - upd_frames++; - if (frame->updatee->header.info == &stg_BLACKHOLE_info) - bhs++; - break; - case STOP_FRAME: - stop_frames++; - break; - case CATCH_FRAME: - catch_frames++; - break; - case SEQ_FRAME: - seq_frames++; - break; - default: - barf("Found non-frame during stack squeezing at %p (prev frame was %p)\n", - frame, prev_frame); - printObj((StgClosure *)prev_frame); - } -#endif - if (get_itbl(frame)->type == UPDATE_FRAME - && frame->updatee->header.info == &stg_BLACKHOLE_info) { - break; - } - } + info = get_ret_itbl(frame); + + switch (info->i.type) { + + case UPDATE_FRAME: - /* Now, we're at the bottom. Frame points to the lowest update - * frame on the stack, and its link actually points to the frame - * above. We have to walk back up the stack, squeezing out empty - * update frames and turning the pointers back around on the way - * back up. - * - * The bottom-most frame (the STOP_FRAME) has not been altered, and - * we never want to eliminate it anyway. Just walk one step up - * before starting to squeeze. When you get to the topmost frame, - * remember that there are still some words above it that might have - * to be moved. - */ - - prev_frame = frame; - frame = next_frame; + SET_INFO(frame, (StgInfoTable *)&stg_marked_upd_frame_info); - prev_was_update_frame = (get_itbl(prev_frame)->type == UPDATE_FRAME); + bh = ((StgUpdateFrame *)frame)->updatee; - /* - * Loop through all of the frames (everything except the very - * bottom). Things are complicated by the fact that we have - * CATCH_FRAMEs and SEQ_FRAMEs interspersed with the update frames. - * We can only squeeze when there are two consecutive UPDATE_FRAMEs. - */ - while (frame != NULL) { - StgPtr sp; - StgPtr frame_bottom = (P_)frame + sizeofW(StgUpdateFrame); - rtsBool is_update_frame; - - next_frame = frame->link; - is_update_frame = (get_itbl(frame)->type == UPDATE_FRAME); + if (closure_IND(bh) || bh->header.info == &stg_BLACKHOLE_info) { + IF_DEBUG(squeeze, debugBelch("suspending duplicate work: %ld words of stack\n", (StgPtr)frame - tso->sp)); - /* Check to see if - * 1. both the previous and current frame are update frames - * 2. the current frame is empty - */ - if (prev_was_update_frame && is_update_frame && - (P_)prev_frame == frame_bottom + displacement) { - - // Now squeeze out the current frame - StgClosure *updatee_keep = prev_frame->updatee; - StgClosure *updatee_bypass = frame->updatee; - -#if DEBUG - IF_DEBUG(gc, belch("@@ squeezing frame at %p", frame)); - squeezes++; -#endif + // If this closure is already an indirection, then + // suspend the computation up to this point: + suspendComputation(cap,tso,(StgPtr)frame); - /* Deal with blocking queues. If both updatees have blocked - * threads, then we should merge the queues into the update - * frame that we're keeping. - * - * Alternatively, we could just wake them up: they'll just go - * straight to sleep on the proper blackhole! This is less code - * and probably less bug prone, although it's probably much - * slower --SDM - */ -#if 0 // do it properly... -# if (!defined(LAZY_BLACKHOLING)) && defined(DEBUG) -# error Unimplemented lazy BH warning. (KSW 1999-01) -# endif - if (GET_INFO(updatee_bypass) == stg_BLACKHOLE_BQ_info - || GET_INFO(updatee_bypass) == stg_CAF_BLACKHOLE_info - ) { - // Sigh. It has one. Don't lose those threads! - if (GET_INFO(updatee_keep) == stg_BLACKHOLE_BQ_info) { - // Urgh. Two queues. Merge them. - P_ keep_tso = ((StgBlockingQueue *)updatee_keep)->blocking_queue; - - while (keep_tso->link != END_TSO_QUEUE) { - keep_tso = keep_tso->link; - } - keep_tso->link = ((StgBlockingQueue *)updatee_bypass)->blocking_queue; + // Now drop the update frame, and arrange to return + // the value to the frame underneath: + tso->sp = (StgPtr)frame + sizeofW(StgUpdateFrame) - 2; + tso->sp[1] = (StgWord)bh; + tso->sp[0] = (W_)&stg_enter_info; - } else { - // For simplicity, just swap the BQ for the BH - P_ temp = updatee_keep; - - updatee_keep = updatee_bypass; - updatee_bypass = temp; - - // Record the swap in the kept frame (below) - prev_frame->updatee = updatee_keep; - } - } -#endif + // And continue with threadPaused; there might be + // yet more computation to suspend. + threadPaused(cap,tso); + return; + } - TICK_UPD_SQUEEZED(); - /* wasn't there something about update squeezing and ticky to be - * sorted out? oh yes: we aren't counting each enter properly - * in this case. See the log somewhere. KSW 1999-04-21 - * - * Check two things: that the two update frames don't point to - * the same object, and that the updatee_bypass isn't already an - * indirection. Both of these cases only happen when we're in a - * block hole-style loop (and there are multiple update frames - * on the stack pointing to the same closure), but they can both - * screw us up if we don't check. - */ - if (updatee_bypass != updatee_keep && !closure_IND(updatee_bypass)) { - // this wakes the threads up - UPD_IND_NOLOCK(updatee_bypass, updatee_keep); - } - - sp = (P_)frame - 1; // sp = stuff to slide - displacement += sizeofW(StgUpdateFrame); - - } else { - // No squeeze for this frame - sp = frame_bottom - 1; // Keep the current frame - - /* Do lazy black-holing. - */ - if (is_update_frame) { - StgBlockingQueue *bh = (StgBlockingQueue *)frame->updatee; - if (bh->header.info != &stg_BLACKHOLE_info && - bh->header.info != &stg_BLACKHOLE_BQ_info && - bh->header.info != &stg_CAF_BLACKHOLE_info) { + if (bh->header.info != &stg_CAF_BLACKHOLE_info) { #if (!defined(LAZY_BLACKHOLING)) && defined(DEBUG) - belch("Unexpected lazy BHing required at 0x%04x",(int)bh); -#endif -#ifdef DEBUG - /* zero out the slop so that the sanity checker can tell - * where the next closure is. - */ - { - StgInfoTable *info = get_itbl(bh); - nat np = info->layout.payload.ptrs, nw = info->layout.payload.nptrs, i; - /* don't zero out slop for a THUNK_SELECTOR, because its layout - * info is used for a different purpose, and it's exactly the - * same size as a BLACKHOLE in any case. - */ - if (info->type != THUNK_SELECTOR) { - for (i = np; i < np + nw; i++) { - ((StgClosure *)bh)->payload[i] = 0; - } - } - } -#endif -#ifdef PROFILING - // @LDV profiling - // We pretend that bh is now dead. - LDV_recordDead_FILL_SLOP_DYNAMIC((StgClosure *)bh); + debugBelch("Unexpected lazy BHing required at 0x%04lx\n",(long)bh); #endif - // - // Todo: maybe use SET_HDR() and remove LDV_recordCreate()? - // - SET_INFO(bh,&stg_BLACKHOLE_info); + // zero out the slop so that the sanity checker can tell + // where the next closure is. + DEBUG_FILL_SLOP(bh); #ifdef PROFILING - // @LDV profiling - // We pretend that bh has just been created. - LDV_recordCreate(bh); + // @LDV profiling + // We pretend that bh is now dead. + LDV_recordDead_FILL_SLOP_DYNAMIC((StgClosure *)bh); #endif - } - } + SET_INFO(bh,&stg_BLACKHOLE_info); - // Fix the link in the current frame (should point to the frame below) - frame->link = prev_frame; - prev_was_update_frame = is_update_frame; + // We pretend that bh has just been created. + LDV_RECORD_CREATE(bh); + } + + frame = (StgClosure *) ((StgUpdateFrame *)frame + 1); + if (prev_was_update_frame) { + words_to_squeeze += sizeofW(StgUpdateFrame); + weight += weight_pending; + weight_pending = 0; + } + prev_was_update_frame = rtsTrue; + break; + + case STOP_FRAME: + goto end; + + // normal stack frames; do nothing except advance the pointer + default: + { + nat frame_size = stack_frame_sizeW(frame); + weight_pending += frame_size; + frame = (StgClosure *)((StgPtr)frame + frame_size); + prev_was_update_frame = rtsFalse; + } + } } - - // Now slide all words from sp up to the next frame - - if (displacement > 0) { - P_ next_frame_bottom; - if (next_frame != NULL) - next_frame_bottom = (P_)next_frame + sizeofW(StgUpdateFrame); - else - next_frame_bottom = tso->sp - 1; - -#if 0 - IF_DEBUG(gc, - belch("sliding [%p, %p] by %ld", sp, next_frame_bottom, - displacement)) -#endif - - while (sp >= next_frame_bottom) { - sp[displacement] = *sp; - sp -= 1; - } +end: + IF_DEBUG(squeeze, + debugBelch("words_to_squeeze: %d, weight: %d, squeeze: %s\n", + words_to_squeeze, weight, + weight < words_to_squeeze ? "YES" : "NO")); + + // Should we squeeze or not? Arbitrary heuristic: we squeeze if + // the number of words we have to shift down is less than the + // number of stack words we squeeze away by doing so. + if (RtsFlags.GcFlags.squeezeUpdFrames == rtsTrue && + weight < words_to_squeeze) { + stackSqueeze(tso, (StgPtr)frame); } - (P_)prev_frame = (P_)frame + displacement; - frame = next_frame; - } - - tso->sp += displacement; - tso->su = prev_frame; -#if 0 - IF_DEBUG(gc, - belch("@@ threadSqueezeStack: squeezed %d update-frames; found %d BHs; found %d update-, %d stop-, %d catch, %d seq-frames", - squeezes, bhs, upd_frames, stop_frames, catch_frames, seq_frames)) -#endif -} - - -/* ----------------------------------------------------------------------------- - * Pausing a thread - * - * We have to prepare for GC - this means doing lazy black holing - * here. We also take the opportunity to do stack squeezing if it's - * turned on. - * -------------------------------------------------------------------------- */ -void -threadPaused(StgTSO *tso) -{ - if ( RtsFlags.GcFlags.squeezeUpdFrames == rtsTrue ) - threadSqueezeStack(tso); // does black holing too - else - threadLazyBlackHole(tso); } /* ----------------------------------------------------------------------------- @@ -4049,49 +4702,18 @@ threadPaused(StgTSO *tso) #if DEBUG void -printMutOnceList(generation *gen) -{ - StgMutClosure *p, *next; - - p = gen->mut_once_list; - next = p->mut_link; - - fprintf(stderr, "@@ Mut once list %p: ", gen->mut_once_list); - for (; p != END_MUT_LIST; p = next, next = p->mut_link) { - fprintf(stderr, "%p (%s), ", - p, info_type((StgClosure *)p)); - } - fputc('\n', stderr); -} - -void printMutableList(generation *gen) { - StgMutClosure *p, *next; - - p = gen->mut_list; - next = p->mut_link; + bdescr *bd; + StgPtr p; - fprintf(stderr, "@@ Mutable list %p: ", gen->mut_list); - for (; p != END_MUT_LIST; p = next, next = p->mut_link) { - fprintf(stderr, "%p (%s), ", - p, info_type((StgClosure *)p)); - } - fputc('\n', stderr); -} + debugBelch("@@ Mutable list %p: ", gen->mut_list); -static inline rtsBool -maybeLarge(StgClosure *closure) -{ - StgInfoTable *info = get_itbl(closure); - - /* closure types that may be found on the new_large_objects list; - see scavenge_large */ - return (info->type == MUT_ARR_PTRS || - info->type == MUT_ARR_PTRS_FROZEN || - info->type == TSO || - info->type == ARR_WORDS); + for (bd = gen->mut_list; bd != NULL; bd = bd->link) { + for (p = bd->start; p < bd->free; p++) { + debugBelch("%p (%s), ", (void *)*p, info_type((StgClosure *)*p)); + } + } + debugBelch("\n"); } - - -#endif // DEBUG +#endif /* DEBUG */