X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Frts%2FGC.c;h=a5dc85d615e58aeb6b2d46122c87f78f9652e2eb;hb=30681e796f707fa109aaf756d4586049f595195d;hp=23b83a5b5f4aafc77b890f7a8a3a35180c77d906;hpb=b915a4cb2b5c22b137165bb85bf19b933875be0a;p=ghc-hetmet.git diff --git a/ghc/rts/GC.c b/ghc/rts/GC.c index 23b83a5..a5dc85d 100644 --- a/ghc/rts/GC.c +++ b/ghc/rts/GC.c @@ -1,7 +1,9 @@ /* ----------------------------------------------------------------------------- - * $Id: GC.c,v 1.5 1999/01/06 12:27:47 simonm Exp $ + * $Id: GC.c,v 1.66 1999/11/09 15:46:49 simonmar Exp $ * - * Two-space garbage collector + * (c) The GHC Team 1998-1999 + * + * Generational garbage collector * * ---------------------------------------------------------------------------*/ @@ -17,21 +19,16 @@ #include "GC.h" #include "BlockAlloc.h" #include "Main.h" -#include "DebugProf.h" +#include "ProfHeap.h" #include "SchedAPI.h" #include "Weak.h" +#include "StablePriv.h" StgCAF* enteredCAFs; -static P_ toHp; /* to-space heap pointer */ -static P_ toHpLim; /* end of current to-space block */ -static bdescr *toHp_bd; /* descriptor of current to-space block */ -static nat blocks = 0; /* number of to-space blocks allocated */ -static bdescr *old_to_space = NULL; /* to-space from the last GC */ -static nat old_to_space_blocks = 0; /* size of previous to-space */ - /* STATIC OBJECT LIST. * + * During GC: * We maintain a linked list of static objects that are still live. * The requirements for this list are: * @@ -53,51 +50,105 @@ static nat old_to_space_blocks = 0; /* size of previous to-space */ * * An object is on the list if its static link field is non-zero; this * means that we have to mark the end of the list with '1', not NULL. + * + * Extra notes for generational GC: + * + * Each generation has a static object list associated with it. When + * collecting generations up to N, we treat the static object lists + * from generations > N as roots. + * + * We build up a static object list while collecting generations 0..N, + * which is then appended to the static object list of generation N+1. + */ +StgClosure* static_objects; /* live static objects */ +StgClosure* scavenged_static_objects; /* static objects scavenged so far */ + +/* N is the oldest generation being collected, where the generations + * are numbered starting at 0. A major GC (indicated by the major_gc + * flag) is when we're collecting all generations. We only attempt to + * deal with static objects and GC CAFs when doing a major GC. + */ +static nat N; +static rtsBool major_gc; + +/* Youngest generation that objects should be evacuated to in + * evacuate(). (Logically an argument to evacuate, but it's static + * a lot of the time so we optimise it into a global variable). */ -#define END_OF_STATIC_LIST stgCast(StgClosure*,1) -static StgClosure* static_objects; -static StgClosure* scavenged_static_objects; +static nat evac_gen; /* WEAK POINTERS */ static StgWeak *old_weak_ptr_list; /* also pending finaliser list */ static rtsBool weak_done; /* all done for this pass */ -/* LARGE OBJECTS. +/* Flag indicating failure to evacuate an object to the desired + * generation. + */ +static rtsBool failed_to_evac; + +/* Old to-space (used for two-space collector only) + */ +bdescr *old_to_space; + +/* Data used for allocation area sizing. */ -static bdescr *new_large_objects; /* large objects evacuated so far */ -static bdescr *scavenged_large_objects; /* large objects scavenged */ +lnat new_blocks; /* blocks allocated during this GC */ +lnat g0s0_pcnt_kept = 30; /* percentage of g0s0 live at last minor GC */ /* ----------------------------------------------------------------------------- Static function declarations -------------------------------------------------------------------------- */ -static StgClosure *evacuate(StgClosure *q); -static void zeroStaticObjectList(StgClosure* first_static); -static void scavenge_stack(StgPtr p, StgPtr stack_end); -static void scavenge_static(void); -static void scavenge_large(void); -static StgPtr scavenge(StgPtr to_scan); -static rtsBool traverse_weak_ptr_list(void); -static void revertDeadCAFs(void); +static StgClosure * evacuate ( StgClosure *q ); +static void zero_static_object_list ( StgClosure* first_static ); +static void zero_mutable_list ( StgMutClosure *first ); +static void revert_dead_CAFs ( void ); + +static rtsBool traverse_weak_ptr_list ( void ); +static void cleanup_weak_ptr_list ( StgWeak **list ); + +static void scavenge_stack ( StgPtr p, StgPtr stack_end ); +static void scavenge_large ( step *step ); +static void scavenge ( step *step ); +static void scavenge_static ( void ); +static void scavenge_mutable_list ( generation *g ); +static void scavenge_mut_once_list ( generation *g ); #ifdef DEBUG -static void gcCAFs(void); +static void gcCAFs ( void ); #endif /* ----------------------------------------------------------------------------- GarbageCollect - This function performs a full copying garbage collection. + 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. + + - 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. + + - 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. + -------------------------------------------------------------------------- */ void GarbageCollect(void (*get_roots)(void)) { - bdescr *bd, *scan_bd, *to_space; - StgPtr scan; - lnat allocated, live; - nat old_nursery_blocks = nursery_blocks; /* for stats */ - nat old_live_blocks = old_to_space_blocks; /* ditto */ + bdescr *bd; + step *step; + lnat live, allocated, collected = 0, copied = 0; + nat g, s; + #ifdef PROFILING CostCentreStack *prev_CCS; #endif @@ -111,64 +162,172 @@ void GarbageCollect(void (*get_roots)(void)) CCCS = CCS_GC; #endif - /* We might have been called from Haskell land by _ccall_GC, in - * which case we need to call threadPaused() because the scheduler - * won't have done it. - */ - if (CurrentTSO) - threadPaused(CurrentTSO); + /* Approximate how much we allocated */ + allocated = calcAllocated(); - /* Approximate how much we allocated: number of blocks in the - * nursery + blocks allocated via allocate() - unused nusery blocks. - * This leaves a little slop at the end of each block, and doesn't - * take into account large objects (ToDo). + /* Figure out which generation to collect */ - allocated = (nursery_blocks * BLOCK_SIZE_W) + allocated_bytes(); - for ( bd = current_nursery->link; bd != NULL; bd = bd->link ) { - allocated -= BLOCK_SIZE_W; + N = 0; + for (g = 0; g < RtsFlags.GcFlags.generations; g++) { + if (generations[g].steps[0].n_blocks >= generations[g].max_blocks) { + N = g; + } } - + major_gc = (N == RtsFlags.GcFlags.generations-1); + /* check stack sanity *before* GC (ToDo: check all threads) */ /*IF_DEBUG(sanity, checkTSO(MainTSO,0)); */ IF_DEBUG(sanity, checkFreeListSanity()); + /* Initialise the static object lists + */ static_objects = END_OF_STATIC_LIST; scavenged_static_objects = END_OF_STATIC_LIST; - new_large_objects = NULL; - scavenged_large_objects = NULL; + /* 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); + } - /* Get a free block for to-space. Extra blocks will be chained on - * as necessary. + /* Save the old to-space if we're doing a two-space collection */ - bd = allocBlock(); - bd->step = 1; /* step 1 identifies to-space */ - toHp = bd->start; - toHpLim = toHp + BLOCK_SIZE_W; - toHp_bd = bd; - to_space = bd; - blocks = 0; - - scan = toHp; - scan_bd = bd; - - /* follow all the roots that the application knows about */ - get_roots(); + if (RtsFlags.GcFlags.generations == 1) { + old_to_space = g0s0->to_space; + g0s0->to_space = NULL; + } + + /* Keep a count of how many new blocks we allocated during this GC + * (used for resizing the allocation area, later). + */ + new_blocks = 0; + + /* 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; + + for (s = 0; s < generations[g].n_steps; s++) { + + /* generation 0, step 0 doesn't need to-space */ + if (g == 0 && s == 0 && RtsFlags.GcFlags.generations > 1) { + continue; + } + + /* Get a free block for to-space. Extra blocks will be chained on + * as necessary. + */ + bd = allocBlock(); + step = &generations[g].steps[s]; + ASSERT(step->gen->no == g); + ASSERT(step->hp ? Bdescr(step->hp)->step == step : rtsTrue); + bd->gen = &generations[g]; + bd->step = step; + bd->link = NULL; + bd->evacuated = 1; /* it's a to-space block */ + step->hp = bd->start; + step->hpLim = step->hp + BLOCK_SIZE_W; + step->hp_bd = bd; + step->to_space = bd; + step->to_blocks = 1; + step->scan = bd->start; + step->scan_bd = bd; + step->new_large_objects = NULL; + step->scavenged_large_objects = NULL; + new_blocks++; + /* mark the large objects as not evacuated yet */ + for (bd = step->large_objects; bd; bd = bd->link) { + bd->evacuated = 0; + } + } + } + + /* make sure the older generations have at least one block to + * allocate into (this makes things easier for copy(), see below. + */ + for (g = N+1; g < RtsFlags.GcFlags.generations; g++) { + for (s = 0; s < generations[g].n_steps; s++) { + step = &generations[g].steps[s]; + if (step->hp_bd == NULL) { + bd = allocBlock(); + bd->gen = &generations[g]; + bd->step = step; + bd->link = NULL; + bd->evacuated = 0; /* *not* a to-space block */ + step->hp = bd->start; + step->hpLim = step->hp + BLOCK_SIZE_W; + step->hp_bd = bd; + step->blocks = bd; + step->n_blocks = 1; + new_blocks++; + } + /* Set the scan pointer for older generations: remember we + * still have to scavenge objects that have been promoted. */ + step->scan = step->hp; + step->scan_bd = step->hp_bd; + step->to_space = NULL; + step->to_blocks = 0; + step->new_large_objects = NULL; + step->scavenged_large_objects = NULL; + } + } - /* And don't forget to mark the TSO if we got here direct from - * Haskell! */ - if (CurrentTSO) { - CurrentTSO = (StgTSO *)MarkRoot((StgClosure *)CurrentTSO); + /* ----------------------------------------------------------------------- + * follow all the roots that we know about: + * - mutable lists from each generation > N + * we want to *scavenge* these roots, not evacuate them: they're not + * going to move in this GC. + * Also: do them in reverse generation order. This is because we + * often want to promote objects that are pointed to by older + * generations early, so we don't have to repeatedly copy them. + * Doing the generations in reverse order ensures that we don't end + * up in the situation where we want to evac an object to gen 3 and + * it has already been evaced to gen 2. + */ + { + int st; + for (g = RtsFlags.GcFlags.generations-1; g > N; g--) { + generations[g].saved_mut_list = generations[g].mut_list; + generations[g].mut_list = END_MUT_LIST; + } + + /* Do the mut-once lists first */ + for (g = RtsFlags.GcFlags.generations-1; g > N; 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]); + } + } + + for (g = RtsFlags.GcFlags.generations-1; g > N; g--) { + scavenge_mutable_list(&generations[g]); + evac_gen = g; + for (st = generations[g].n_steps-1; st >= 0; st--) { + scavenge(&generations[g].steps[st]); + } + } } + /* follow all the roots that the application knows about. + */ + evac_gen = 0; + get_roots(); + /* Mark the weak pointer list, and prepare to detect dead weak * pointers. */ - markWeakList(); old_weak_ptr_list = weak_ptr_list; weak_ptr_list = NULL; weak_done = rtsFalse; + /* Mark the stable pointer table. + */ + markStablePtrTable(major_gc); + #ifdef INTERPRETER { /* ToDo: To fix the caf leak, we need to make the commented out @@ -176,209 +335,344 @@ void GarbageCollect(void (*get_roots)(void)) * the CAF document. */ extern void markHugsObjects(void); -#if 0 - /* ToDo: This (undefined) function should contain the scavenge - * loop immediately below this block of code - but I'm not sure - * enough of the details to do this myself. - */ - scavengeEverything(); - /* revert dead CAFs and update enteredCAFs list */ - revertDeadCAFs(); -#endif markHugsObjects(); -#if 0 - /* This will keep the CAFs and the attached BCOs alive - * but the values will have been reverted - */ - scavengeEverything(); -#endif } #endif - /* Then scavenge all the objects we picked up on the first pass. - * We may require multiple passes to find all the static objects, - * large objects and normal objects. + /* ------------------------------------------------------------------------- + * Repeatedly scavenge all the areas we know about until there's no + * more scavenging to be done. */ { + rtsBool flag; loop: - if (static_objects != END_OF_STATIC_LIST) { + flag = rtsFalse; + + /* scavenge static objects */ + if (major_gc && static_objects != END_OF_STATIC_LIST) { scavenge_static(); } - if (toHp_bd != scan_bd || scan < toHp) { - scan = scavenge(scan); - scan_bd = Bdescr(scan); - goto loop; - } - if (new_large_objects != NULL) { - scavenge_large(); - goto loop; + + /* When scavenging the older generations: Objects may have been + * evacuated from generations <= N into older generations, and we + * need to scavenge these objects. We're going to try to ensure that + * any evacuations that occur move the objects into at least the + * same generation as the object being scavenged, otherwise we + * have to create new entries on the mutable list for the older + * generation. + */ + + /* scavenge each step in generations 0..maxgen */ + { + int gen, st; + loop2: + for (gen = RtsFlags.GcFlags.generations-1; gen >= 0; gen--) { + for (st = generations[gen].n_steps-1; st >= 0 ; st--) { + if (gen == 0 && st == 0 && RtsFlags.GcFlags.generations > 1) { + continue; + } + step = &generations[gen].steps[st]; + evac_gen = gen; + if (step->hp_bd != step->scan_bd || step->scan < step->hp) { + scavenge(step); + flag = rtsTrue; + goto loop2; + } + if (step->new_large_objects != NULL) { + scavenge_large(step); + flag = rtsTrue; + goto loop2; + } + } + } } + if (flag) { goto loop; } + /* must be last... */ if (traverse_weak_ptr_list()) { /* returns rtsTrue if evaced something */ goto loop; } } - /* tidy up the end of the to-space chain */ - toHp_bd->free = toHp; - toHp_bd->link = NULL; - + /* Final traversal of the weak pointer list (see comment by + * cleanUpWeakPtrList below). + */ + cleanup_weak_ptr_list(&weak_ptr_list); + + /* Now see which stable names are still alive. + */ + gcStablePtrTable(major_gc); + /* revert dead CAFs and update enteredCAFs list */ - revertDeadCAFs(); - - /* mark the garbage collected CAFs as dead */ -#ifdef DEBUG - gcCAFs(); -#endif + revert_dead_CAFs(); - zeroStaticObjectList(scavenged_static_objects); - - /* approximate amount of live data (doesn't take into account slop - * at end of each block). ToDo: this more accurately. + /* Set the maximum blocks for the oldest generation, based on twice + * the amount of live data now, adjusted to fit the maximum heap + * size if necessary. + * + * This is an approximation, since in the worst case we'll need + * twice the amount of live data plus whatever space the other + * generations need. */ - live = blocks * BLOCK_SIZE_W + ((lnat)toHp_bd->free - - (lnat)toHp_bd->start) / sizeof(W_); + if (RtsFlags.GcFlags.generations > 1) { + if (major_gc) { + oldest_gen->max_blocks = + stg_max(oldest_gen->steps[0].to_blocks * RtsFlags.GcFlags.oldGenFactor, + RtsFlags.GcFlags.minOldGenSize); + if (oldest_gen->max_blocks > RtsFlags.GcFlags.maxHeapSize / 2) { + oldest_gen->max_blocks = RtsFlags.GcFlags.maxHeapSize / 2; + if (((int)oldest_gen->max_blocks - + (int)oldest_gen->steps[0].to_blocks) < + (RtsFlags.GcFlags.pcFreeHeap * + RtsFlags.GcFlags.maxHeapSize / 200)) { + heapOverflow(); + } + } + } + } - /* Free the to-space from the last GC, as it has now been collected. - * we may be able to re-use these blocks in creating a new nursery, - * below. If not, the blocks will probably be re-used for to-space - * in the next GC. + /* run through all the generations/steps and tidy up */ - if (old_to_space != NULL) { - freeChain(old_to_space); + copied = new_blocks * BLOCK_SIZE_W; + for (g = 0; g < RtsFlags.GcFlags.generations; g++) { + + if (g <= N) { + generations[g].collections++; /* for stats */ + } + + for (s = 0; s < generations[g].n_steps; s++) { + bdescr *next; + step = &generations[g].steps[s]; + + if (!(g == 0 && s == 0 && RtsFlags.GcFlags.generations > 1)) { + /* Tidy the end of the to-space chains */ + step->hp_bd->free = step->hp; + step->hp_bd->link = NULL; + /* stats information: how much we copied */ + if (g <= N) { + copied -= step->hp_bd->start + BLOCK_SIZE_W - + step->hp_bd->free; + } + } + + /* for generations we collected... */ + if (g <= N) { + + collected += step->n_blocks * BLOCK_SIZE_W; /* for stats */ + + /* free old memory and shift to-space into from-space for all + * the collected steps (except the allocation area). These + * freed blocks will probaby be quickly recycled. + */ + if (!(g == 0 && s == 0)) { + freeChain(step->blocks); + step->blocks = step->to_space; + step->n_blocks = step->to_blocks; + step->to_space = NULL; + step->to_blocks = 0; + for (bd = step->blocks; bd != NULL; bd = bd->link) { + bd->evacuated = 0; /* now from-space */ + } + } + + /* LARGE OBJECTS. The current live large objects are chained on + * scavenged_large, having been moved during garbage + * collection from large_objects. Any objects left on + * large_objects list are therefore dead, so we free them here. + */ + for (bd = step->large_objects; bd != NULL; bd = next) { + next = bd->link; + freeGroup(bd); + bd = next; + } + for (bd = step->scavenged_large_objects; bd != NULL; bd = bd->link) { + bd->evacuated = 0; + } + step->large_objects = step->scavenged_large_objects; + + /* Set the maximum blocks for this generation, interpolating + * between the maximum size of the oldest and youngest + * generations. + * + * max_blocks = oldgen_max_blocks * G + * ---------------------- + * oldest_gen + */ + if (g != 0) { +#if 0 + generations[g].max_blocks = (oldest_gen->max_blocks * g) + / (RtsFlags.GcFlags.generations-1); +#endif + generations[g].max_blocks = oldest_gen->max_blocks; + } + + /* for older generations... */ + } else { + + /* For older generations, we need to append the + * scavenged_large_object list (i.e. large objects that have been + * promoted during this GC) to the large_object list for that step. + */ + for (bd = step->scavenged_large_objects; bd; bd = next) { + next = bd->link; + bd->evacuated = 0; + dbl_link_onto(bd, &step->large_objects); + } + + /* add the new blocks we promoted during this GC */ + step->n_blocks += step->to_blocks; + } + } } - old_to_space = to_space; - old_to_space_blocks = blocks; + + /* Guess the amount of live data for stats. */ + live = calcLive(); /* Free the small objects allocated via allocate(), since this will - * all have been copied into to-space now. + * all have been copied into G0S1 now. */ if (small_alloc_list != NULL) { freeChain(small_alloc_list); } small_alloc_list = NULL; alloc_blocks = 0; - alloc_blocks_lim = stg_max(blocks,RtsFlags.GcFlags.minAllocAreaSize); + alloc_Hp = NULL; + alloc_HpLim = NULL; + alloc_blocks_lim = RtsFlags.GcFlags.minAllocAreaSize; - /* LARGE OBJECTS. The current live large objects are chained on - * scavenged_large_objects, having been moved during garbage - * collection from large_alloc_list. Any objects left on - * large_alloc list are therefore dead, so we free them here. + /* Two-space collector: + * Free the old to-space, and estimate the amount of live data. */ - { - bdescr *bd, *next; - bd = large_alloc_list; - while (bd != NULL) { - next = bd->link; - freeGroup(bd); - bd = next; + if (RtsFlags.GcFlags.generations == 1) { + nat blocks; + + if (old_to_space != NULL) { + freeChain(old_to_space); + } + for (bd = g0s0->to_space; bd != NULL; bd = bd->link) { + bd->evacuated = 0; /* now from-space */ } - large_alloc_list = scavenged_large_objects; - } + /* For a two-space collector, we need to resize the nursery. */ + + /* set up a new nursery. Allocate a nursery size based on a + * function of the amount of live data (currently a factor of 2, + * should be configurable (ToDo)). Use the blocks from the old + * nursery if possible, freeing up any left over blocks. + * + * If we get near the maximum heap size, then adjust our nursery + * size accordingly. If the nursery is the same size as the live + * data (L), then we need 3L bytes. We can reduce the size of the + * nursery to bring the required memory down near 2L bytes. + * + * A normal 2-space collector would need 4L bytes to give the same + * performance we get from 3L bytes, reducing to the same + * performance at 2L bytes. + */ + blocks = g0s0->to_blocks; - /* check sanity after GC */ - IF_DEBUG(sanity, checkHeap(to_space,1)); - /*IF_DEBUG(sanity, checkTSO(MainTSO,1)); */ - IF_DEBUG(sanity, checkFreeListSanity()); + if ( blocks * RtsFlags.GcFlags.oldGenFactor * 2 > + RtsFlags.GcFlags.maxHeapSize ) { + int adjusted_blocks; /* signed on purpose */ + int pc_free; + + adjusted_blocks = (RtsFlags.GcFlags.maxHeapSize - 2 * blocks); + IF_DEBUG(gc, fprintf(stderr, "Near maximum heap size of 0x%x blocks, blocks = %d, adjusted to %d\n", RtsFlags.GcFlags.maxHeapSize, blocks, adjusted_blocks)); + pc_free = adjusted_blocks * 100 / RtsFlags.GcFlags.maxHeapSize; + if (pc_free < RtsFlags.GcFlags.pcFreeHeap) /* might even be < 0 */ { + heapOverflow(); + } + blocks = adjusted_blocks; + + } else { + blocks *= RtsFlags.GcFlags.oldGenFactor; + if (blocks < RtsFlags.GcFlags.minAllocAreaSize) { + blocks = RtsFlags.GcFlags.minAllocAreaSize; + } + } + resizeNursery(blocks); + + } else { + /* Generational collector: + * If the user has given us a suggested heap size, adjust our + * allocation area to make best use of the memory available. + */ -#ifdef DEBUG - /* symbol-table based profiling */ - heapCensus(to_space); -#endif + if (RtsFlags.GcFlags.heapSizeSuggestion) { + int blocks; + nat needed = calcNeeded(); /* approx blocks needed at next GC */ - /* set up a new nursery. Allocate a nursery size based on a - * function of the amount of live data (currently a factor of 2, - * should be configurable (ToDo)). Use the blocks from the old - * nursery if possible, freeing up any left over blocks. - * - * If we get near the maximum heap size, then adjust our nursery - * size accordingly. If the nursery is the same size as the live - * data (L), then we need 3L bytes. We can reduce the size of the - * nursery to bring the required memory down near 2L bytes. - * - * A normal 2-space collector would need 4L bytes to give the same - * performance we get from 3L bytes, reducing to the same - * performance at 2L bytes. - */ - if ( blocks * 4 > RtsFlags.GcFlags.maxHeapSize ) { - int adjusted_blocks; /* signed on purpose */ - int pc_free; - - adjusted_blocks = (RtsFlags.GcFlags.maxHeapSize - 2 * blocks); - IF_DEBUG(gc, fprintf(stderr, "Near maximum heap size of 0x%x blocks, blocks = %d, adjusted to %d\n", RtsFlags.GcFlags.maxHeapSize, blocks, adjusted_blocks)); - pc_free = adjusted_blocks * 100 / RtsFlags.GcFlags.maxHeapSize; - if (pc_free < RtsFlags.GcFlags.pcFreeHeap) /* might even be < 0 */ { - heapOverflow(); - } - blocks = adjusted_blocks; + /* Guess how much will be live in generation 0 step 0 next time. + * A good approximation is the obtained by finding the + * percentage of g0s0 that was live at the last minor GC. + */ + if (N == 0) { + g0s0_pcnt_kept = (new_blocks * 100) / g0s0->n_blocks; + } - } else { - blocks *= 2; - if (blocks < RtsFlags.GcFlags.minAllocAreaSize) { - blocks = RtsFlags.GcFlags.minAllocAreaSize; + /* Estimate a size for the allocation area based on the + * information available. We might end up going slightly under + * or over the suggested heap size, but we should be pretty + * close on average. + * + * Formula: suggested - needed + * ---------------------------- + * 1 + g0s0_pcnt_kept/100 + * + * where 'needed' is the amount of memory needed at the next + * collection for collecting all steps except g0s0. + */ + blocks = + (((int)RtsFlags.GcFlags.heapSizeSuggestion - (int)needed) * 100) / + (100 + (int)g0s0_pcnt_kept); + + if (blocks < (int)RtsFlags.GcFlags.minAllocAreaSize) { + blocks = RtsFlags.GcFlags.minAllocAreaSize; + } + + resizeNursery((nat)blocks); } } + + /* mark the garbage collected CAFs as dead */ +#ifdef DEBUG + if (major_gc) { gcCAFs(); } +#endif - if (nursery_blocks < blocks) { - IF_DEBUG(gc, fprintf(stderr, "Increasing size of nursery to %d blocks\n", - blocks)); - nursery = allocNursery(nursery,blocks-nursery_blocks); - } else { - bdescr *next_bd = nursery; - - IF_DEBUG(gc, fprintf(stderr, "Decreasing size of nursery to %d blocks\n", - blocks)); - for (bd = nursery; nursery_blocks > blocks; nursery_blocks--) { - next_bd = bd->link; - freeGroup(bd); - bd = next_bd; - } - nursery = bd; + /* zero the scavenged static object list */ + if (major_gc) { + zero_static_object_list(scavenged_static_objects); } - - current_nursery = nursery; - nursery_blocks = blocks; - /* set the step number for each block in the nursery to zero */ - for (bd = nursery; bd != NULL; bd = bd->link) { - bd->step = 0; - bd->free = bd->start; - } - for (bd = to_space; bd != NULL; bd = bd->link) { - bd->step = 0; - } - for (bd = large_alloc_list; bd != NULL; bd = bd->link) { - bd->step = 0; - } + /* Reset the nursery + */ + resetNurseries(); + + /* start any pending finalizers */ + scheduleFinalizers(old_weak_ptr_list); + + /* check sanity after GC */ + IF_DEBUG(sanity, checkSanity(N)); + + /* extra GC trace info */ + IF_DEBUG(gc, stat_describe_gens()); #ifdef DEBUG - /* check that we really have the right number of blocks in the - * nursery, or things could really get screwed up. - */ - { - nat i = 0; - for (bd = nursery; bd != NULL; bd = bd->link) { - ASSERT(bd->free == bd->start); - ASSERT(bd->step == 0); - i++; - } - ASSERT(i == nursery_blocks); - } + /* symbol-table based profiling */ + /* heapCensus(to_space); */ /* ToDo */ #endif - /* start any pending finalisers */ - scheduleFinalisers(old_weak_ptr_list); - /* restore enclosing cost centre */ #ifdef PROFILING + heapCensus(); CCCS = prev_CCS; #endif + /* check for memory leaks if sanity checking is on */ + IF_DEBUG(sanity, memInventory()); + /* ok, GC over: tell the stats department what happened. */ - stat_endGC(allocated, - (old_nursery_blocks + old_live_blocks) * BLOCK_SIZE_W, - live, ""); + stat_endGC(allocated, collected, live, copied, N); } /* ----------------------------------------------------------------------------- @@ -394,68 +688,81 @@ void GarbageCollect(void (*get_roots)(void)) pointer code decide which weak pointers are dead - if there are no new live weak pointers, then all the currently unreachable ones are dead. + + For generational GC: we just don't try to finalize weak pointers in + older generations than the one we're collecting. This could + probably be optimised by keeping per-generation lists of weak + pointers, but for a few weak pointers this scheme will work. -------------------------------------------------------------------------- */ static rtsBool traverse_weak_ptr_list(void) { StgWeak *w, **last_w, *next_w; - StgClosure *target; - const StgInfoTable *info; + StgClosure *new; rtsBool flag = rtsFalse; if (weak_done) { return rtsFalse; } + /* doesn't matter where we evacuate values/finalizers to, since + * these pointers are treated as roots (iff the keys are alive). + */ + evac_gen = 0; + last_w = &old_weak_ptr_list; for (w = old_weak_ptr_list; w; w = next_w) { - target = w->key; - loop: - info = get_itbl(target); - switch (info->type) { - - case IND: - case IND_STATIC: - case IND_PERM: - case IND_OLDGEN: - case IND_OLDGEN_PERM: - /* follow indirections */ - target = ((StgInd *)target)->indirectee; - goto loop; - case EVACUATED: - /* If key is alive, evacuate value and finaliser and - * place weak ptr on new weak ptr list. - */ - IF_DEBUG(weak, fprintf(stderr,"Weak pointer still alive at %p\n", w)); - w->key = ((StgEvacuated *)target)->evacuee; + /* First, this weak pointer might have been evacuated. If so, + * remove the forwarding pointer from the weak_ptr_list. + */ + if (get_itbl(w)->type == EVACUATED) { + w = (StgWeak *)((StgEvacuated *)w)->evacuee; + *last_w = w; + } + + /* There might be a DEAD_WEAK on the list if finalizeWeak# was + * called on a live weak pointer object. Just remove it. + */ + if (w->header.info == &DEAD_WEAK_info) { + next_w = ((StgDeadWeak *)w)->link; + *last_w = next_w; + continue; + } + + ASSERT(get_itbl(w)->type == WEAK); + + /* Now, check whether the key is reachable. + */ + if ((new = isAlive(w->key))) { + w->key = new; + /* evacuate the value and finalizer */ w->value = evacuate(w->value); - w->finaliser = evacuate(w->finaliser); - + 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; - break; - - default: /* key is dead */ + IF_DEBUG(weak, fprintf(stderr,"Weak pointer still alive at %p -> %p\n", w, w->key)); + continue; + } + else { last_w = &(w->link); next_w = w->link; - break; + continue; } } /* If we didn't make any changes, then we can go round and kill all * the dead weak pointers. The old_weak_ptr list is used as a list - * of pending finalisers later on. + * of pending finalizers later on. */ if (flag == rtsFalse) { + cleanup_weak_ptr_list(&old_weak_ptr_list); for (w = old_weak_ptr_list; w; w = w->link) { - w->value = evacuate(w->value); - w->finaliser = evacuate(w->finaliser); + w->finalizer = evacuate(w->finalizer); } weak_done = rtsTrue; } @@ -463,103 +770,398 @@ traverse_weak_ptr_list(void) return rtsTrue; } -StgClosure *MarkRoot(StgClosure *root) -{ - root = evacuate(root); - return root; -} - -static __inline__ StgClosure *copy(StgClosure *src, W_ size) -{ - P_ to, from, dest; - - if (toHp + size >= toHpLim) { - bdescr *bd = allocBlock(); - toHp_bd->free = toHp; - toHp_bd->link = bd; - bd->step = 1; /* step 1 identifies to-space */ - toHp = bd->start; - toHpLim = toHp + BLOCK_SIZE_W; - toHp_bd = bd; - blocks++; - } - - dest = toHp; - toHp += size; - for(to = dest, from = (P_)src; size>0; --size) { - *to++ = *from++; - } - return (StgClosure *)dest; -} - -static __inline__ void upd_evacuee(StgClosure *p, StgClosure *dest) -{ - StgEvacuated *q = (StgEvacuated *)p; - - SET_INFO(q,&EVACUATED_info); - q->evacuee = dest; -} - /* ----------------------------------------------------------------------------- - Evacuate a large object - - This just consists of removing the object from the (doubly-linked) - large_alloc_list, and linking it on to the (singly-linked) - new_large_objects list, from where it will be scavenged later. + After GC, the live weak pointer list may have forwarding pointers + on it, because a weak pointer object was evacuated after being + moved to the live weak pointer list. We remove those forwarding + pointers here. + + Also, we don't consider weak pointer objects to be reachable, but + we must nevertheless consider them to be "live" and retain them. + Therefore any weak pointer objects which haven't as yet been + evacuated need to be evacuated now. -------------------------------------------------------------------------- */ -static inline void evacuate_large(StgPtr p) +static void +cleanup_weak_ptr_list ( StgWeak **list ) { - bdescr *bd = Bdescr(p); + StgWeak *w, **last_w; - /* should point to the beginning of the block */ - ASSERT(((W_)p & BLOCK_MASK) == 0); - - /* already evacuated? */ - if (bd->step == 1) { - return; - } + last_w = list; + for (w = *list; w; w = w->link) { - /* remove from large_alloc_list */ - if (bd->back) { - bd->back->link = bd->link; - } else { /* first object in the list */ - large_alloc_list = bd->link; - } - if (bd->link) { - bd->link->back = bd->back; + if (get_itbl(w)->type == EVACUATED) { + w = (StgWeak *)((StgEvacuated *)w)->evacuee; + *last_w = w; + } + + if (Bdescr((P_)w)->evacuated == 0) { + (StgClosure *)w = evacuate((StgClosure *)w); + *last_w = w; + } + last_w = &(w->link); } - - /* link it on to the evacuated large object list */ - bd->link = new_large_objects; - new_large_objects = bd; - bd->step = 1; -} +} /* ----------------------------------------------------------------------------- - Evacuate - - This is called (eventually) for every live object in the system. + isAlive determines whether the given closure is still alive (after + a garbage collection) or not. It returns the new address of the + closure if it is alive, or NULL otherwise. -------------------------------------------------------------------------- */ -static StgClosure *evacuate(StgClosure *q) +StgClosure * +isAlive(StgClosure *p) { - StgClosure *to; const StgInfoTable *info; -loop: - /* 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)))); + while (1) { - info = get_itbl(q); - switch (info -> type) { + 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 closures in generations that we're not collecting. */ + if (LOOKS_LIKE_STATIC(p) || Bdescr((P_)p)->gen->no > N) { + return p; + } + + switch (info->type) { + + case IND: + case IND_STATIC: + case IND_PERM: + case IND_OLDGEN: /* rely on compatible layout with StgInd */ + case IND_OLDGEN_PERM: + /* follow indirections */ + p = ((StgInd *)p)->indirectee; + continue; + + case EVACUATED: + /* alive! */ + return ((StgEvacuated *)p)->evacuee; + + default: + /* dead. */ + return NULL; + } + } +} + +StgClosure * +MarkRoot(StgClosure *root) +{ + return evacuate(root); +} + +static void addBlock(step *step) +{ + bdescr *bd = allocBlock(); + bd->gen = step->gen; + bd->step = step; + + if (step->gen->no <= N) { + bd->evacuated = 1; + } else { + bd->evacuated = 0; + } + + step->hp_bd->free = step->hp; + step->hp_bd->link = bd; + step->hp = bd->start; + step->hpLim = step->hp + BLOCK_SIZE_W; + step->hp_bd = bd; + step->to_blocks++; + new_blocks++; +} + +static __inline__ void +upd_evacuee(StgClosure *p, StgClosure *dest) +{ + p->header.info = &EVACUATED_info; + ((StgEvacuated *)p)->evacuee = dest; +} + +static __inline__ StgClosure * +copy(StgClosure *src, nat size, step *step) +{ + P_ to, from, dest; + + 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 (step->gen->no < evac_gen) { +#ifdef NO_EAGER_PROMOTION + failed_to_evac = rtsTrue; +#else + step = &generations[evac_gen].steps[0]; +#endif + } + + /* chain a new block onto the to-space for the destination step if + * necessary. + */ + if (step->hp + size >= step->hpLim) { + addBlock(step); + } + + for(to = step->hp, from = (P_)src; size>0; --size) { + *to++ = *from++; + } + + dest = step->hp; + step->hp = to; + upd_evacuee(src,(StgClosure *)dest); + return (StgClosure *)dest; +} + +/* Special version of copy() for when we only want to copy the info + * pointer of an object, but reserve some padding after it. This is + * used to optimise evacuation of BLACKHOLEs. + */ + +static __inline__ StgClosure * +copyPart(StgClosure *src, nat size_to_reserve, nat size_to_copy, step *step) +{ + P_ dest, to, from; + + TICK_GC_WORDS_COPIED(size_to_copy); + if (step->gen->no < evac_gen) { +#ifdef NO_EAGER_PROMOTION + failed_to_evac = rtsTrue; +#else + step = &generations[evac_gen].steps[0]; +#endif + } + + if (step->hp + size_to_reserve >= step->hpLim) { + addBlock(step); + } + + for(to = step->hp, from = (P_)src; size_to_copy>0; --size_to_copy) { + *to++ = *from++; + } + + dest = step->hp; + step->hp += size_to_reserve; + upd_evacuee(src,(StgClosure *)dest); + return (StgClosure *)dest; +} + +/* ----------------------------------------------------------------------------- + Evacuate a large object + + This just consists of removing the object from the (doubly-linked) + large_alloc_list, and linking it on to the (singly-linked) + new_large_objects list, from where it will be scavenged later. + + Convention: bd->evacuated is /= 0 for a large object that has been + evacuated, or 0 otherwise. + -------------------------------------------------------------------------- */ + +static inline void +evacuate_large(StgPtr p, rtsBool mutable) +{ + bdescr *bd = Bdescr(p); + step *step; + + /* should point to the beginning of the block */ + ASSERT(((W_)p & BLOCK_MASK) == 0); + + /* already evacuated? */ + if (bd->evacuated) { + /* Don't forget to set the failed_to_evac flag if we didn't get + * the desired destination (see comments in evacuate()). + */ + if (bd->gen->no < evac_gen) { + failed_to_evac = rtsTrue; + TICK_GC_FAILED_PROMOTION(); + } + return; + } + + step = bd->step; + /* remove from large_object list */ + if (bd->back) { + bd->back->link = bd->link; + } else { /* first object in the list */ + step->large_objects = bd->link; + } + if (bd->link) { + bd->link->back = bd->back; + } + + /* link it on to the evacuated large object list of the destination step + */ + step = bd->step->to; + if (step->gen->no < evac_gen) { +#ifdef NO_EAGER_PROMOTION + failed_to_evac = rtsTrue; +#else + step = &generations[evac_gen].steps[0]; +#endif + } + + bd->step = step; + bd->gen = step->gen; + bd->link = step->new_large_objects; + step->new_large_objects = bd; + bd->evacuated = 1; + + if (mutable) { + recordMutable((StgMutClosure *)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 *step; + + step = &gen->steps[0]; + + /* chain a new block onto the to-space for the destination step if + * necessary. + */ + if (step->hp + sizeofW(StgIndOldGen) >= step->hpLim) { + addBlock(step); + } + + q = (StgMutVar *)step->hp; + step->hp += sizeofW(StgMutVar); + + SET_HDR(q,&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. + + The caller to evacuate specifies a desired generation in the + evac_gen global variable. The following conditions apply to + evacuating an object which resides in generation M when we're + collecting up to generation N + + if M >= evac_gen + if M > N do nothing + else evac to step->to + + if M < evac_gen evac to evac_gen, step 0 + + if the object is already evacuated, then we check which generation + it now resides in. + + if M >= evac_gen do nothing + if M < evac_gen set failed_to_evac flag to indicate that we + didn't manage to evacuate this object into evac_gen. + + -------------------------------------------------------------------------- */ + + +static StgClosure * +evacuate(StgClosure *q) +{ + StgClosure *to; + bdescr *bd = NULL; + step *step; + const StgInfoTable *info; + +loop: + if (HEAP_ALLOCED(q)) { + 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 make an IND_OLDGEN object. + */ + if (bd->gen->no < evac_gen) { + /* nope */ + failed_to_evac = rtsTrue; + TICK_GC_FAILED_PROMOTION(); + } + return q; + } + step = bd->step->to; + } +#ifdef DEBUG + else step = NULL; /* make sure copy() will crash if HEAP_ALLOCED is wrong */ +#endif + + /* make sure the info pointer is into text space */ + ASSERT(q && (LOOKS_LIKE_GHC_INFO(GET_INFO(q)) + || IS_HUGS_CONSTR_INFO(GET_INFO(q)))); + info = get_itbl(q); + + switch (info -> type) { case BCO: - to = copy(q,bco_sizeW(stgCast(StgBCO*,q))); - upd_evacuee(q,to); + { + nat size = bco_sizeW((StgBCO*)q); + + if (size >= LARGE_OBJECT_THRESHOLD/sizeof(W_)) { + evacuate_large((P_)q, rtsFalse); + to = q; + } else { + /* just copy the block */ + to = copy(q,size,step); + } + return to; + } + + case MUT_VAR: + ASSERT(q->header.info != &MUT_CONS_info); + case MVAR: + to = copy(q,sizeW_fromITBL(info),step); + recordMutable((StgMutClosure *)to); return to; + case FUN_1_0: + case FUN_0_1: + case CONSTR_1_0: + case CONSTR_0_1: + return copy(q,sizeofW(StgHeader)+1,step); + + case THUNK_1_0: /* here because of MIN_UPD_SIZE */ + case THUNK_0_1: + case THUNK_1_1: + case THUNK_0_2: + case THUNK_2_0: +#ifdef NO_PROMOTE_THUNKS + if (bd->gen->no == 0 && + bd->step->no != 0 && + bd->step->no == bd->gen->n_steps-1) { + step = bd->step; + } +#endif + return copy(q,sizeofW(StgHeader)+2,step); + + case FUN_1_1: + case FUN_0_2: + case FUN_2_0: + case CONSTR_1_1: + case CONSTR_0_2: + case CONSTR_2_0: + return copy(q,sizeofW(StgHeader)+2,step); + case FUN: case THUNK: case CONSTR: @@ -569,34 +1171,41 @@ loop: case CAF_ENTERED: case WEAK: case FOREIGN: - case MUT_VAR: - case MVAR: - to = copy(q,sizeW_fromITBL(info)); - upd_evacuee(q,to); - return to; + case STABLE_NAME: + return copy(q,sizeW_fromITBL(info),step); case CAF_BLACKHOLE: + case SE_CAF_BLACKHOLE: + case SE_BLACKHOLE: case BLACKHOLE: - to = copy(q,BLACKHOLE_sizeW()); - upd_evacuee(q,to); + return copyPart(q,BLACKHOLE_sizeW(),sizeofW(StgHeader),step); + + case BLACKHOLE_BQ: + to = copy(q,BLACKHOLE_sizeW(),step); + recordMutable((StgMutClosure *)to); return to; case THUNK_SELECTOR: { const StgInfoTable* selectee_info; - StgClosure* selectee = stgCast(StgSelector*,q)->selectee; + 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: { - StgNat32 offset = info->layout.selector_offset; + StgWord32 offset = info->layout.selector_offset; /* check that the size is in range */ ASSERT(offset < - (StgNat32)(selectee_info->layout.payload.ptrs + + (StgWord32)(selectee_info->layout.payload.ptrs + selectee_info->layout.payload.nptrs)); /* perform the selection! */ @@ -606,8 +1215,15 @@ loop: * with the evacuation, just update the source address with * a pointer to the (evacuated) constructor field. */ - if (IS_USER_PTR(q) && Bdescr((P_)q)->step == 1) { - return q; + if (HEAP_ALLOCED(q)) { + bdescr *bd = Bdescr((P_)q); + if (bd->evacuated) { + if (bd->gen->no < evac_gen) { + failed_to_evac = rtsTrue; + TICK_GC_FAILED_PROMOTION(); + } + return q; + } } /* otherwise, carry on and evacuate this constructor field, @@ -633,44 +1249,65 @@ loop: goto selector_loop; 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 THUNK_SELECTOR: /* aargh - do recursively???? */ case CAF_UNENTERED: case CAF_BLACKHOLE: + case SE_CAF_BLACKHOLE: + case SE_BLACKHOLE: case BLACKHOLE: + case BLACKHOLE_BQ: /* not evaluated yet */ break; default: - barf("evacuate: THUNK_SELECTOR: strange selectee"); + barf("evacuate: THUNK_SELECTOR: strange selectee %d", + (int)(selectee_info->type)); } } - to = copy(q,THUNK_SELECTOR_sizeW()); - upd_evacuee(q,to); - return to; + return copy(q,THUNK_SELECTOR_sizeW(),step); case IND: case IND_OLDGEN: /* follow chains of indirections, don't evacuate them */ - q = stgCast(StgInd*,q)->indirectee; + q = ((StgInd*)q)->indirectee; goto loop; - case CONSTR_STATIC: 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: - /* don't want to evacuate these, but we do want to follow pointers - * from SRTs - see scavenge_static. - */ + if (major_gc && IND_STATIC_LINK((StgClosure *)q) == NULL) { + IND_STATIC_LINK((StgClosure *)q) = static_objects; + static_objects = (StgClosure *)q; + } + return q; - /* put the object on the static list, if necessary. - */ - if (STATIC_LINK(info,(StgClosure *)q) == NULL) { + case CONSTR_STATIC: + if (major_gc && STATIC_LINK(info,(StgClosure *)q) == NULL) { STATIC_LINK(info,(StgClosure *)q) = static_objects; static_objects = (StgClosure *)q; } - /* fall through */ + return q; case CONSTR_INTLIKE: case CONSTR_CHARLIKE: @@ -697,33 +1334,57 @@ loop: case PAP: /* these are special - the payload is a copy of a chunk of stack, tagging and all. */ - to = copy(q,pap_sizeW(stgCast(StgPAP*,q))); - upd_evacuee(q,to); - return to; + return copy(q,pap_sizeW(stgCast(StgPAP*,q)),step); case EVACUATED: - /* Already evacuated, just return the forwarding address */ - return stgCast(StgEvacuated*,q)->evacuee; + /* Already evacuated, just return the forwarding address. + * HOWEVER: if the requested destination generation (evac_gen) is + * older than the actual generation (because the object was + * already evacuated to a younger generation) then we have to + * set the failed_to_evac flag to indicate that we couldn't + * manage to promote the object to the desired generation. + */ + if (evac_gen > 0) { /* optimisation */ + StgClosure *p = ((StgEvacuated*)q)->evacuee; + if (Bdescr((P_)p)->gen->no < evac_gen) { + /* fprintf(stderr,"evac failed!\n");*/ + failed_to_evac = rtsTrue; + TICK_GC_FAILED_PROMOTION(); + } + } + return ((StgEvacuated*)q)->evacuee; - case MUT_ARR_WORDS: case ARR_WORDS: - case MUT_ARR_PTRS: - case MUT_ARR_PTRS_FROZEN: - case ARR_PTRS: { nat size = arr_words_sizeW(stgCast(StgArrWords*,q)); if (size >= LARGE_OBJECT_THRESHOLD/sizeof(W_)) { - evacuate_large((P_)q); + evacuate_large((P_)q, rtsFalse); return q; } else { /* just copy the block */ - to = copy(q,size); - upd_evacuee(q,to); - return to; + return copy(q,size,step); } } + case MUT_ARR_PTRS: + case MUT_ARR_PTRS_FROZEN: + { + nat size = mut_arr_ptrs_sizeW(stgCast(StgMutArrPtrs*,q)); + + if (size >= LARGE_OBJECT_THRESHOLD/sizeof(W_)) { + evacuate_large((P_)q, info->type == MUT_ARR_PTRS); + to = q; + } else { + /* just copy the block */ + to = copy(q,size,step); + if (info->type == MUT_ARR_PTRS) { + recordMutable((StgMutClosure *)to); + } + } + return to; + } + case TSO: { StgTSO *tso = stgCast(StgTSO *,q); @@ -733,14 +1394,14 @@ loop: /* Large TSOs don't get moved, so no relocation is required. */ if (size >= LARGE_OBJECT_THRESHOLD/sizeof(W_)) { - evacuate_large((P_)q); + evacuate_large((P_)q, rtsTrue); return q; /* To evacuate a small TSO, we need to relocate the update frame * list it contains. */ } else { - StgTSO *new_tso = (StgTSO *)copy((StgClosure *)tso,tso_sizeW(tso)); + StgTSO *new_tso = (StgTSO *)copy((StgClosure *)tso,tso_sizeW(tso),step); diff = (StgPtr)new_tso - (StgPtr)tso; /* In *words* */ @@ -750,7 +1411,8 @@ loop: new_tso->splim = (StgPtr)new_tso->splim + diff; relocate_TSO(tso, new_tso); - upd_evacuee(q,(StgClosure *)new_tso); + + recordMutable((StgMutClosure *)new_tso); return (StgClosure *)new_tso; } } @@ -761,7 +1423,7 @@ loop: return q; default: - barf("evacuate: strange closure type"); + barf("evacuate: strange closure type %d", (int)(info->type)); } barf("evacuate"); @@ -811,7 +1473,7 @@ relocate_TSO(StgTSO *src, StgTSO *dest) break; default: - barf("relocate_TSO"); + barf("relocate_TSO %d", (int)(get_itbl(su)->type)); } break; } @@ -820,7 +1482,7 @@ relocate_TSO(StgTSO *src, StgTSO *dest) } static inline void -evacuate_srt(const StgInfoTable *info) +scavenge_srt(const StgInfoTable *info) { StgClosure **srt, **srt_end; @@ -831,181 +1493,744 @@ evacuate_srt(const StgInfoTable *info) srt = stgCast(StgClosure **,info->srt); srt_end = srt + info->srt_len; for (; srt < srt_end; srt++) { - evacuate(*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 ( stgCast(unsigned long,*srt) & 0x1 ) { + evacuate(*stgCast(StgClosure**,(stgCast(unsigned long, *srt) & ~0x1))); + } else { + evacuate(*srt); + } +#else + evacuate(*srt); +#endif } } -static StgPtr -scavenge(StgPtr to_scan) +/* ----------------------------------------------------------------------------- + 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 *step) { - StgPtr p; + StgPtr p, q; const StgInfoTable *info; bdescr *bd; + nat saved_evac_gen = evac_gen; /* used for temporarily changing evac_gen */ - p = to_scan; - bd = Bdescr((P_)p); + p = step->scan; + bd = step->scan_bd; + + failed_to_evac = rtsFalse; /* scavenge phase - standard breadth-first scavenging of the * evacuated objects */ - while (bd != toHp_bd || p < toHp) { + while (bd != step->hp_bd || p < step->hp) { + + /* If we're at the end of this block, move on to the next block */ + if (bd != step->hp_bd && p == bd->free) { + bd = bd->link; + p = bd->start; + continue; + } + + q = p; /* save ptr to object */ + + ASSERT(p && (LOOKS_LIKE_GHC_INFO(GET_INFO((StgClosure *)p)) + || IS_HUGS_CONSTR_INFO(GET_INFO((StgClosure *)p)))); + + info = get_itbl((StgClosure *)p); + switch (info -> type) { + + case BCO: + { + StgBCO* bco = stgCast(StgBCO*,p); + nat i; + for (i = 0; i < bco->n_ptrs; i++) { + bcoConstCPtr(bco,i) = evacuate(bcoConstCPtr(bco,i)); + } + p += bco_sizeW(bco); + break; + } + + 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); + p += sizeofW(StgMVar); + evac_gen = saved_evac_gen; + break; + } + + case THUNK_2_0: + case FUN_2_0: + scavenge_srt(info); + case CONSTR_2_0: + ((StgClosure *)p)->payload[1] = evacuate(((StgClosure *)p)->payload[1]); + ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]); + p += sizeofW(StgHeader) + 2; + break; + + case THUNK_1_0: + scavenge_srt(info); + ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]); + p += sizeofW(StgHeader) + 2; /* MIN_UPD_SIZE */ + break; + + case FUN_1_0: + scavenge_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 */ + break; + + case FUN_0_1: + scavenge_srt(info); + case CONSTR_0_1: + p += sizeofW(StgHeader) + 1; + break; + + case THUNK_0_2: + case FUN_0_2: + scavenge_srt(info); + case CONSTR_0_2: + p += sizeofW(StgHeader) + 2; + break; + + case THUNK_1_1: + case FUN_1_1: + scavenge_srt(info); + case CONSTR_1_1: + ((StgClosure *)p)->payload[0] = evacuate(((StgClosure *)p)->payload[0]); + p += sizeofW(StgHeader) + 2; + break; + + case FUN: + case THUNK: + scavenge_srt(info); + /* fall through */ + + case CONSTR: + case WEAK: + case FOREIGN: + case STABLE_NAME: + { + 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 += info->layout.payload.nptrs; + break; + } + + case IND_PERM: + if (step->gen->no != 0) { + SET_INFO(((StgClosure *)p), &IND_OLDGEN_PERM_info); + } + /* 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); + break; + + case CAF_UNENTERED: + { + StgCAF *caf = (StgCAF *)p; + + caf->body = evacuate(caf->body); + if (failed_to_evac) { + failed_to_evac = rtsFalse; + recordOldToNewPtrs((StgMutClosure *)p); + } else { + caf->mut_link = NULL; + } + p += sizeofW(StgCAF); + break; + } + + case CAF_ENTERED: + { + StgCAF *caf = (StgCAF *)p; + + caf->body = evacuate(caf->body); + caf->value = evacuate(caf->value); + if (failed_to_evac) { + failed_to_evac = rtsFalse; + recordOldToNewPtrs((StgMutClosure *)p); + } else { + caf->mut_link = NULL; + } + p += sizeofW(StgCAF); + break; + } + + case MUT_VAR: + /* ignore MUT_CONSs */ + if (((StgMutVar *)p)->header.info != &MUT_CONS_info) { + evac_gen = 0; + ((StgMutVar *)p)->var = evacuate(((StgMutVar *)p)->var); + evac_gen = saved_evac_gen; + } + p += sizeofW(StgMutVar); + break; + + case CAF_BLACKHOLE: + case SE_CAF_BLACKHOLE: + case SE_BLACKHOLE: + case BLACKHOLE: + p += BLACKHOLE_sizeW(); + break; + + case BLACKHOLE_BQ: + { + StgBlockingQueue *bh = (StgBlockingQueue *)p; + (StgClosure *)bh->blocking_queue = + evacuate((StgClosure *)bh->blocking_queue); + if (failed_to_evac) { + failed_to_evac = rtsFalse; + recordMutable((StgMutClosure *)bh); + } + p += BLACKHOLE_sizeW(); + break; + } + + case THUNK_SELECTOR: + { + StgSelector *s = (StgSelector *)p; + s->selectee = evacuate(s->selectee); + p += THUNK_SELECTOR_sizeW(); + break; + } + + case IND: + case IND_OLDGEN: + barf("scavenge:IND???\n"); + + case CONSTR_INTLIKE: + case CONSTR_CHARLIKE: + case CONSTR_STATIC: + case CONSTR_NOCAF_STATIC: + case THUNK_STATIC: + case FUN_STATIC: + case IND_STATIC: + /* Shouldn't see a static object here. */ + barf("scavenge: STATIC object\n"); + + case RET_BCO: + case RET_SMALL: + case RET_VEC_SMALL: + case RET_BIG: + case RET_VEC_BIG: + case RET_DYN: + case UPDATE_FRAME: + case STOP_FRAME: + case CATCH_FRAME: + case SEQ_FRAME: + /* Shouldn't see stack frames here. */ + barf("scavenge: stack frame\n"); + + 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 = stgCast(StgPAP*,p); + + pap->fun = evacuate(pap->fun); + scavenge_stack((P_)pap->payload, (P_)pap->payload + pap->n_args); + p += pap_sizeW(pap); + break; + } + + case ARR_WORDS: + /* nothing to follow */ + p += arr_words_sizeW(stgCast(StgArrWords*,p)); + break; + + case MUT_ARR_PTRS: + /* follow everything */ + { + StgPtr next; + + evac_gen = 0; /* repeatedly mutable */ + next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p); + for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) { + (StgClosure *)*p = evacuate((StgClosure *)*p); + } + evac_gen = saved_evac_gen; + break; + } + + case MUT_ARR_PTRS_FROZEN: + /* follow everything */ + { + StgPtr start = p, next; + + next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p); + for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) { + (StgClosure *)*p = evacuate((StgClosure *)*p); + } + if (failed_to_evac) { + /* we can do this easier... */ + recordMutable((StgMutClosure *)start); + failed_to_evac = rtsFalse; + } + break; + } + + case TSO: + { + StgTSO *tso; + + tso = (StgTSO *)p; + evac_gen = 0; + /* 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->block_info.closure = evacuate(tso->block_info.closure); + } + /* scavenge this thread's stack */ + scavenge_stack(tso->sp, &(tso->stack[tso->stack_size])); + evac_gen = saved_evac_gen; + p += tso_sizeW(tso); + break; + } + + case BLOCKED_FETCH: + case FETCH_ME: + case EVACUATED: + barf("scavenge: unimplemented/strange closure type\n"); + + default: + barf("scavenge"); + } + + /* 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). + */ + if (failed_to_evac) { + mkMutCons((StgClosure *)q, &generations[evac_gen]); + failed_to_evac = rtsFalse; + } + } + + step->scan_bd = bd; + step->scan = p; +} + +/* ----------------------------------------------------------------------------- + Scavenge one object. + + This is used for objects that are temporarily marked as mutable + because they contain old-to-new generation pointers. Only certain + objects can have this property. + -------------------------------------------------------------------------- */ +static rtsBool +scavenge_one(StgClosure *p) +{ + const StgInfoTable *info; + rtsBool no_luck; + + ASSERT(p && (LOOKS_LIKE_GHC_INFO(GET_INFO(p)) + || IS_HUGS_CONSTR_INFO(GET_INFO(p)))); + + info = get_itbl(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 THUNK: + case THUNK_1_0: + case THUNK_0_1: + case THUNK_1_1: + case THUNK_0_2: + case THUNK_2_0: + case CONSTR: + case CONSTR_1_0: + case CONSTR_0_1: + case CONSTR_1_1: + case CONSTR_0_2: + case CONSTR_2_0: + case WEAK: + case FOREIGN: + case IND_PERM: + case IND_OLDGEN_PERM: + case CAF_UNENTERED: + { + StgPtr q, end; + + end = (P_)p->payload + info->layout.payload.ptrs; + for (q = (P_)p->payload; q < end; q++) { + (StgClosure *)*q = evacuate((StgClosure *)*q); + } + break; + } + + case CAF_BLACKHOLE: + case SE_CAF_BLACKHOLE: + case SE_BLACKHOLE: + case BLACKHOLE: + break; + + case THUNK_SELECTOR: + { + StgSelector *s = (StgSelector *)p; + s->selectee = evacuate(s->selectee); + break; + } + + case AP_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; + + pap->fun = evacuate(pap->fun); + scavenge_stack((P_)pap->payload, (P_)pap->payload + pap->n_args); + 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. + */ + break; + + default: + barf("scavenge_one: strange object"); + } + + 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_mut_once_list(generation *gen) +{ + const StgInfoTable *info; + StgMutClosure *p, *next, *new_list; - /* If we're at the end of this block, move on to the next block */ - if (bd != toHp_bd && p == bd->free) { - bd = bd->link; - p = bd->start; - continue; - } + p = gen->mut_once_list; + new_list = END_MUT_LIST; + next = p->mut_link; - ASSERT(p && (LOOKS_LIKE_GHC_INFO(GET_INFO((StgClosure *)p)) - || IS_HUGS_CONSTR_INFO(GET_INFO((StgClosure *)p)))); + evac_gen = gen->no; + failed_to_evac = rtsFalse; - info = get_itbl((StgClosure *)p); - switch (info -> type) { + for (; p != END_MUT_LIST; p = next, next = p->mut_link) { - case BCO: - { - StgBCO* bco = stgCast(StgBCO*,p); - nat i; - for (i = 0; i < bco->n_ptrs; i++) { - bcoConstCPtr(bco,i) = evacuate(bcoConstCPtr(bco,i)); + /* 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); + 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); + +#if 0 + /* Debugging code to print out the size of the thing we just + * promoted + */ + { + StgPtr start = gen->steps[0].scan; + bdescr *start_bd = gen->steps[0].scan_bd; + nat size = 0; + scavenge(&gen->steps[0]); + if (start_bd != gen->steps[0].scan_bd) { + size += (P_)BLOCK_ROUND_UP(start) - start; + start_bd = start_bd->link; + while (start_bd != gen->steps[0].scan_bd) { + size += BLOCK_SIZE_W; + start_bd = start_bd->link; + } + size += gen->steps[0].scan - + (P_)BLOCK_ROUND_DOWN(gen->steps[0].scan); + } else { + size = gen->steps[0].scan - start; } - p += bco_sizeW(bco); - continue; + fprintf(stderr,"evac IND_OLDGEN: %d bytes\n", size * sizeof(W_)); } +#endif - case FUN: - case THUNK: - evacuate_srt(info); - /* fall through */ - - case CONSTR: - case WEAK: - case FOREIGN: - case MVAR: + /* 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_VAR: - case IND_PERM: - case IND_OLDGEN_PERM: - case CAF_UNENTERED: + /* 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. + */ + ASSERT(p->header.info == &MUT_CONS_info); + if (scavenge_one(((StgMutVar *)p)->var) == rtsTrue) { + /* didn't manage to promote everything, so put the + * MUT_CONS back on the list. + */ + p->mut_link = new_list; + new_list = p; + } + continue; + case CAF_ENTERED: - { - 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); + { + StgCAF *caf = (StgCAF *)p; + caf->body = evacuate(caf->body); + caf->value = evacuate(caf->value); + if (failed_to_evac) { + failed_to_evac = rtsFalse; + p->mut_link = new_list; + new_list = p; + } else { + p->mut_link = NULL; } - p += info->layout.payload.nptrs; - continue; } + continue; - case CAF_BLACKHOLE: - case BLACKHOLE: + case CAF_UNENTERED: { - StgBlackHole *bh = (StgBlackHole *)p; - (StgClosure *)bh->blocking_queue = - evacuate((StgClosure *)bh->blocking_queue); - p += BLACKHOLE_sizeW(); - continue; + StgCAF *caf = (StgCAF *)p; + caf->body = evacuate(caf->body); + if (failed_to_evac) { + failed_to_evac = rtsFalse; + p->mut_link = new_list; + new_list = p; + } else { + p->mut_link = NULL; + } } + continue; - case THUNK_SELECTOR: - { - StgSelector *s = (StgSelector *)p; - s->selectee = evacuate(s->selectee); - p += THUNK_SELECTOR_sizeW(); - continue; - } + default: + /* shouldn't have anything else on the mutables list */ + barf("scavenge_mut_once_list: strange object? %d", (int)(info->type)); + } + } - case IND: - case IND_OLDGEN: - barf("scavenge:IND???\n"); + gen->mut_once_list = new_list; +} - case CONSTR_INTLIKE: - case CONSTR_CHARLIKE: - case CONSTR_STATIC: - case CONSTR_NOCAF_STATIC: - case THUNK_STATIC: - case FUN_STATIC: - case IND_STATIC: - /* Shouldn't see a static object here. */ - barf("scavenge: STATIC object\n"); - case RET_BCO: - case RET_SMALL: - case RET_VEC_SMALL: - case RET_BIG: - case RET_VEC_BIG: - case RET_DYN: - case UPDATE_FRAME: - case STOP_FRAME: - case CATCH_FRAME: - case SEQ_FRAME: - /* Shouldn't see stack frames here. */ - barf("scavenge: stack frame\n"); +static void +scavenge_mutable_list(generation *gen) +{ + const StgInfoTable *info; + StgMutClosure *p, *next; - 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... + 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); + switch(info->type) { + + case MUT_ARR_PTRS_FROZEN: + /* remove this guy from the mutable list, but follow the ptrs + * anyway (and make sure they get promoted to this gen). */ - { - StgPAP* pap = stgCast(StgPAP*,p); + { + StgPtr end, q; + + end = (P_)p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p); + evac_gen = gen->no; + for (q = (P_)((StgMutArrPtrs *)p)->payload; q < end; q++) { + (StgClosure *)*q = evacuate((StgClosure *)*q); + } + evac_gen = 0; - pap->fun = evacuate(pap->fun); - scavenge_stack((P_)pap->payload, (P_)pap->payload + pap->n_args); - p += pap_sizeW(pap); + if (failed_to_evac) { + failed_to_evac = rtsFalse; + p->mut_link = gen->mut_list; + gen->mut_list = p; + } continue; } - - case ARR_WORDS: - case MUT_ARR_WORDS: - /* nothing to follow */ - p += arr_words_sizeW(stgCast(StgArrWords*,p)); - continue; - case ARR_PTRS: case MUT_ARR_PTRS: - case MUT_ARR_PTRS_FROZEN: /* follow everything */ + p->mut_link = gen->mut_list; + gen->mut_list = p; { - StgPtr next; - - next = p + arr_ptrs_sizeW(stgCast(StgArrPtrs*,p)); - for (p = (P_)((StgArrPtrs *)p)->payload; p < next; p++) { - (StgClosure *)*p = evacuate((StgClosure *)*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; } + + case MUT_VAR: + /* MUT_CONS is a kind of MUT_VAR, except that we try to remove + * it from the mutable list if possible by promoting whatever it + * points to. + */ + ASSERT(p->header.info != &MUT_CONS_info); + ((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; - - tso = (StgTSO *)p; - /* chase the link field for any TSOs on the same queue */ + StgTSO *tso = (StgTSO *)p; + (StgClosure *)tso->link = evacuate((StgClosure *)tso->link); - /* scavenge this thread's stack */ + if ( tso->why_blocked == BlockedOnMVar + || tso->why_blocked == BlockedOnBlackHole) { + tso->block_info.closure = evacuate(tso->block_info.closure); + } scavenge_stack(tso->sp, &(tso->stack[tso->stack_size])); - p += tso_sizeW(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; } - case BLOCKED_FETCH: - case FETCH_ME: - case EVACUATED: - barf("scavenge: unimplemented/strange closure type\n"); + /* 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; default: - barf("scavenge"); + /* shouldn't have anything else on the mutables list */ + barf("scavenge_mutable_list: strange object? %d", (int)(info->type)); } } - return (P_)p; -} - -/* scavenge_static is the scavenge code for a static closure. - */ +} static void scavenge_static(void) @@ -1013,38 +2238,53 @@ scavenge_static(void) StgClosure* p = static_objects; const StgInfoTable *info; + /* Always evacuate straight to the oldest generation for static + * objects */ + evac_gen = oldest_gen->no; + /* keep going until we've scavenged all the objects on the linked list... */ while (p != END_OF_STATIC_LIST) { + info = get_itbl(p); + /* make sure the info pointer is into text space */ - ASSERT(p && LOOKS_LIKE_GHC_INFO(GET_INFO(p))); ASSERT(p && (LOOKS_LIKE_GHC_INFO(GET_INFO(p)) || IS_HUGS_CONSTR_INFO(GET_INFO(p)))); - - info = get_itbl(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; scavenged_static_objects = p; - + switch (info -> type) { - + case IND_STATIC: { StgInd *ind = (StgInd *)p; ind->indirectee = evacuate(ind->indirectee); + + /* might fail to evacuate it, in which case we have to pop it + * back on the mutable list (and take it off the + * scavenged_static list because the static link and mut link + * pointers are one and the same). + */ + if (failed_to_evac) { + failed_to_evac = rtsFalse; + scavenged_static_objects = STATIC_LINK(info,p); + ((StgMutClosure *)ind)->mut_link = oldest_gen->mut_once_list; + oldest_gen->mut_once_list = (StgMutClosure *)ind; + } break; } case THUNK_STATIC: case FUN_STATIC: - evacuate_srt(info); + scavenge_srt(info); /* fall through */ - + case CONSTR_STATIC: { StgPtr q, next; @@ -1061,6 +2301,8 @@ scavenge_static(void) barf("scavenge_static"); } + ASSERT(failed_to_evac == rtsFalse); + /* get the next static object from the list. Remeber, there might * be more stuff on this list now that we've done some evacuating! * (static_objects is a global) @@ -1080,7 +2322,7 @@ scavenge_stack(StgPtr p, StgPtr stack_end) { StgPtr q; const StgInfoTable* info; - StgNat32 bitmap; + StgWord32 bitmap; /* * Each time around this loop, we are looking at a chunk of stack @@ -1089,24 +2331,22 @@ scavenge_stack(StgPtr p, StgPtr stack_end) */ while (p < stack_end) { - q = *stgCast(StgPtr*,p); + q = *(P_ *)p; /* If we've got a tag, skip over that many words on the stack */ - if (IS_ARG_TAG(stgCast(StgWord,q))) { + if (IS_ARG_TAG((W_)q)) { p += ARG_SIZE(q); p++; continue; } /* Is q a pointer to a closure? */ - if (! LOOKS_LIKE_GHC_INFO(q)) { - + if (! LOOKS_LIKE_GHC_INFO(q) ) { #ifdef DEBUG - if (LOOKS_LIKE_STATIC(q)) { /* Is it a static closure? */ + if ( 0 && LOOKS_LIKE_STATIC_CLOSURE(q) ) { /* Is it a static closure? */ ASSERT(closure_STATIC(stgCast(StgClosure*,q))); - } - /* otherwise, must be a pointer into the allocation space. - */ + } + /* otherwise, must be a pointer into the allocation space. */ #endif (StgClosure *)*p = evacuate((StgClosure *)q); @@ -1119,14 +2359,14 @@ scavenge_stack(StgPtr p, StgPtr stack_end) * record. All activation records have 'bitmap' style layout * info. */ - info = get_itbl(stgCast(StgClosure*,p)); + info = get_itbl((StgClosure *)p); switch (info->type) { /* Dynamic bitmap: the mask is stored on the stack */ case RET_DYN: - bitmap = stgCast(StgRetDyn*,p)->liveness; - p = &payloadWord(stgCast(StgRetDyn*,p),0); + bitmap = ((StgRetDyn *)p)->liveness; + p = (P_)&((StgRetDyn *)p)->payload[0]; goto small_bitmap; /* probably a slow-entry point return address: */ @@ -1136,30 +2376,58 @@ scavenge_stack(StgPtr p, StgPtr stack_end) goto follow_srt; /* Specialised code for update frames, since they're so common. - * We *know* the updatee points to a BLACKHOLE or CAF_BLACKHOLE, - * so just inline the code to evacuate it here. + * 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; StgClosure *to; - StgClosureType type = get_itbl(frame->updatee)->type; + nat type = get_itbl(frame->updatee)->type; + p += sizeofW(StgUpdateFrame); if (type == EVACUATED) { frame->updatee = evacuate(frame->updatee); - p += sizeofW(StgUpdateFrame); continue; } else { - ASSERT(type == BLACKHOLE || type == CAF_BLACKHOLE); - to = copy(frame->updatee, BLACKHOLE_sizeW()); - upd_evacuee(frame->updatee,to); - frame->updatee = to; - p += sizeofW(StgUpdateFrame); - continue; + bdescr *bd = Bdescr((P_)frame->updatee); + step *step; + if (bd->gen->no > N) { + if (bd->gen->no < evac_gen) { + failed_to_evac = rtsTrue; + } + continue; + } + + /* Don't promote blackholes */ + step = bd->step; + if (!(step->gen->no == 0 && + step->no != 0 && + step->no == step->gen->n_steps-1)) { + step = step->to; + } + + switch (type) { + case BLACKHOLE: + case CAF_BLACKHOLE: + to = copyPart(frame->updatee, BLACKHOLE_sizeW(), + sizeofW(StgHeader), step); + frame->updatee = to; + continue; + case BLACKHOLE_BQ: + to = copy(frame->updatee, BLACKHOLE_sizeW(), step); + 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"); + } } } - /* small bitmap (< 32 entries) */ + /* small bitmap (< 32 entries, or 64 on a 64-bit machine) */ case RET_BCO: case RET_SMALL: case RET_VEC_SMALL: @@ -1178,7 +2446,7 @@ scavenge_stack(StgPtr p, StgPtr stack_end) } follow_srt: - evacuate_srt(info); + scavenge_srt(info); continue; /* large bitmap (> 32 entries) */ @@ -1222,32 +2490,33 @@ scavenge_stack(StgPtr p, StgPtr stack_end) /*----------------------------------------------------------------------------- scavenge the large object list. + + evac_gen set by caller; similar games played with evac_gen as with + scavenge() - see comment at the top of scavenge(). Most large + objects are (repeatedly) mutable, so most of the time evac_gen will + be zero. --------------------------------------------------------------------------- */ static void -scavenge_large(void) +scavenge_large(step *step) { bdescr *bd; StgPtr p; const StgInfoTable* info; + nat saved_evac_gen = evac_gen; /* used for temporarily changing evac_gen */ - bd = new_large_objects; + evac_gen = 0; /* most objects are mutable */ + bd = step->new_large_objects; - for (; bd != NULL; bd = new_large_objects) { + for (; bd != NULL; bd = step->new_large_objects) { /* take this object *off* the large objects list and put it on * the scavenged large objects list. This is so that we can * treat new_large_objects as a stack and push new objects on * the front when evacuating. */ - new_large_objects = bd->link; - /* scavenged_large_objects is doubly linked */ - bd->link = scavenged_large_objects; - bd->back = NULL; - if (scavenged_large_objects) { - scavenged_large_objects->back = bd; - } - scavenged_large_objects = bd; + step->new_large_objects = bd->link; + dbl_link_onto(bd, &step->scavenged_large_objects); p = bd->start; info = get_itbl(stgCast(StgClosure*,p)); @@ -1257,21 +2526,35 @@ scavenge_large(void) /* only certain objects can be "large"... */ case ARR_WORDS: - case MUT_ARR_WORDS: /* nothing to follow */ continue; - case ARR_PTRS: case MUT_ARR_PTRS: - case MUT_ARR_PTRS_FROZEN: /* follow everything */ { StgPtr next; - next = p + arr_ptrs_sizeW(stgCast(StgArrPtrs*,p)); - for (p = (P_)((StgArrPtrs *)p)->payload; p < next; p++) { + next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p); + for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) { + (StgClosure *)*p = evacuate((StgClosure *)*p); + } + continue; + } + + case MUT_ARR_PTRS_FROZEN: + /* follow everything */ + { + StgPtr start = p, next; + + evac_gen = saved_evac_gen; /* not really mutable */ + next = p + mut_arr_ptrs_sizeW((StgMutArrPtrs*)p); + for (p = (P_)((StgMutArrPtrs *)p)->payload; p < next; p++) { (StgClosure *)*p = evacuate((StgClosure *)*p); } + evac_gen = 0; + if (failed_to_evac) { + recordMutable((StgMutClosure *)start); + } continue; } @@ -1279,9 +2562,11 @@ scavenge_large(void) { StgBCO* bco = stgCast(StgBCO*,p); nat i; + evac_gen = saved_evac_gen; for (i = 0; i < bco->n_ptrs; i++) { bcoConstCPtr(bco,i) = evacuate(bcoConstCPtr(bco,i)); } + evac_gen = 0; continue; } @@ -1292,6 +2577,10 @@ scavenge_large(void) tso = (StgTSO *)p; /* 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->block_info.closure = evacuate(tso->block_info.closure); + } /* scavenge this thread's stack */ scavenge_stack(tso->sp, &(tso->stack[tso->stack_size])); continue; @@ -1302,8 +2591,9 @@ scavenge_large(void) } } } + static void -zeroStaticObjectList(StgClosure* first_static) +zero_static_object_list(StgClosure* first_static) { StgClosure* p; StgClosure* link; @@ -1316,52 +2606,61 @@ zeroStaticObjectList(StgClosure* first_static) } } +/* 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; + } +} + /* ----------------------------------------------------------------------------- Reverting CAFs - -------------------------------------------------------------------------- */ void RevertCAFs(void) { - while (enteredCAFs != END_CAF_LIST) { - StgCAF* caf = enteredCAFs; - const StgInfoTable *info = get_itbl(caf); - - enteredCAFs = caf->link; - ASSERT(get_itbl(caf)->type == CAF_ENTERED); - SET_INFO(caf,&CAF_UNENTERED_info); - caf->value = stgCast(StgClosure*,0xdeadbeef); - caf->link = stgCast(StgCAF*,0xdeadbeef); - } + while (enteredCAFs != END_CAF_LIST) { + StgCAF* caf = enteredCAFs; + + enteredCAFs = caf->link; + ASSERT(get_itbl(caf)->type == CAF_ENTERED); + SET_INFO(caf,&CAF_UNENTERED_info); + caf->value = stgCast(StgClosure*,0xdeadbeef); + caf->link = stgCast(StgCAF*,0xdeadbeef); + } + enteredCAFs = END_CAF_LIST; } -void revertDeadCAFs(void) +void revert_dead_CAFs(void) { StgCAF* caf = enteredCAFs; enteredCAFs = END_CAF_LIST; while (caf != END_CAF_LIST) { - StgCAF* next = caf->link; - - switch(GET_INFO(caf)->type) { - case EVACUATED: - { - /* This object has been evacuated, it must be live. */ - StgCAF* new = stgCast(StgCAF*,stgCast(StgEvacuated*,caf)->evacuee); - new->link = enteredCAFs; - enteredCAFs = new; - break; - } - case CAF_ENTERED: - { - SET_INFO(caf,&CAF_UNENTERED_info); - caf->value = stgCast(StgClosure*,0xdeadbeef); - caf->link = stgCast(StgCAF*,0xdeadbeef); - break; - } - default: - barf("revertDeadCAFs: enteredCAFs list corrupted"); - } - caf = next; + StgCAF *next, *new; + next = caf->link; + new = (StgCAF*)isAlive((StgClosure*)caf); + if (new) { + new->link = enteredCAFs; + enteredCAFs = new; + } else { + ASSERT(0); + SET_INFO(caf,&CAF_UNENTERED_info); + caf->value = (StgClosure*)0xdeadbeef; + caf->link = (StgCAF*)0xdeadbeef; + } + caf = next; } } @@ -1427,7 +2726,7 @@ static void threadLazyBlackHole(StgTSO *tso) { StgUpdateFrame *update_frame; - StgBlackHole *bh; + StgBlockingQueue *bh; StgPtr stack_end; stack_end = &tso->stack[tso->stack_size]; @@ -1441,21 +2740,25 @@ threadLazyBlackHole(StgTSO *tso) break; case UPDATE_FRAME: - bh = stgCast(StgBlackHole*,update_frame->updatee); + bh = (StgBlockingQueue *)update_frame->updatee; /* 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 == &BLACKHOLE_info) { + return; + } - /* Don't for now: when we enter a CAF, we create a black hole on - * the heap and make the update frame point to it. Thus the - * above optimisation doesn't apply. - */ - if (bh->header.info != &BLACKHOLE_info - && bh->header.info != &CAF_BLACKHOLE_info) { + if (bh->header.info != &BLACKHOLE_BQ_info && + bh->header.info != &CAF_BLACKHOLE_info) { +#if (!defined(LAZY_BLACKHOLING)) && defined(DEBUG) + fprintf(stderr,"Unexpected lazy BHing required at 0x%04x\n",(int)bh); +#endif SET_INFO(bh,&BLACKHOLE_info); - bh->blocking_queue = stgCast(StgTSO*,&END_TSO_QUEUE_closure); } update_frame = update_frame->link; @@ -1504,16 +2807,21 @@ threadSqueezeStack(StgTSO *tso) * added to the stack, rather than the way we see them in this * walk. (It makes the next loop less confusing.) * - * Could stop if we find an update frame pointing to a black hole, - * but see comment in threadLazyBlackHole(). + * Stop if we find an update frame pointing to a black hole + * (see comment in threadLazyBlackHole()). */ next_frame = NULL; - while ((P_)frame < bottom - 1) { /* bottom - 1 is the STOP_FRAME */ + /* 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 (get_itbl(frame)->type == UPDATE_FRAME + && frame->updatee->header.info == &BLACKHOLE_info) { + break; + } } /* Now, we're at the bottom. Frame points to the lowest update @@ -1573,20 +2881,21 @@ threadSqueezeStack(StgTSO *tso) * slower --SDM */ #if 0 /* do it properly... */ - if (GET_INFO(updatee_bypass) == BLACKHOLE_info +# if (!defined(LAZY_BLACKHOLING)) && defined(DEBUG) +# error Unimplemented lazy BH warning. (KSW 1999-01) +# endif + if (GET_INFO(updatee_bypass) == BLACKHOLE_BQ_info || GET_INFO(updatee_bypass) == CAF_BLACKHOLE_info ) { /* Sigh. It has one. Don't lose those threads! */ - if (GET_INFO(updatee_keep) == BLACKHOLE_info - || GET_INFO(updatee_keep) == CAF_BLACKHOLE_info - ) { + if (GET_INFO(updatee_keep) == BLACKHOLE_BQ_info) { /* Urgh. Two queues. Merge them. */ - P_ keep_tso = ((StgBlackHole *)updatee_keep)->blocking_queue; + P_ keep_tso = ((StgBlockingQueue *)updatee_keep)->blocking_queue; while (keep_tso->link != END_TSO_QUEUE) { keep_tso = keep_tso->link; } - keep_tso->link = ((StgBlackHole *)updatee_bypass)->blocking_queue; + keep_tso->link = ((StgBlockingQueue *)updatee_bypass)->blocking_queue; } else { /* For simplicity, just swap the BQ for the BH */ @@ -1602,7 +2911,11 @@ threadSqueezeStack(StgTSO *tso) #endif TICK_UPD_SQUEEZED(); - UPD_IND(updatee_bypass, updatee_keep); /* this wakes the threads up */ + /* 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 + */ + UPD_IND_NOLOCK(updatee_bypass, updatee_keep); /* this wakes the threads up */ sp = (P_)frame - 1; /* sp = stuff to slide */ displacement += sizeofW(StgUpdateFrame); @@ -1614,12 +2927,14 @@ threadSqueezeStack(StgTSO *tso) /* Do lazy black-holing. */ if (is_update_frame) { - StgBlackHole *bh = (StgBlackHole *)frame->updatee; - if (bh->header.info != &BLACKHOLE_info - && bh->header.info != &CAF_BLACKHOLE_info - ) { + StgBlockingQueue *bh = (StgBlockingQueue *)frame->updatee; + if (bh->header.info != &BLACKHOLE_info && + bh->header.info != &BLACKHOLE_BQ_info && + bh->header.info != &CAF_BLACKHOLE_info) { +#if (!defined(LAZY_BLACKHOLING)) && defined(DEBUG) + fprintf(stderr,"Unexpected lazy BHing required at 0x%04x\n",(int)bh); +#endif SET_INFO(bh,&BLACKHOLE_info); - bh->blocking_queue = stgCast(StgTSO*,&END_TSO_QUEUE_closure); } }