/* -----------------------------------------------------------------------------
*
- * (c) The GHC Team 1998-2006
+ * (c) The GHC Team 1998-2008
*
* Generational garbage collector: evacuation functions
*
*
* ---------------------------------------------------------------------------*/
+#include "PosixSource.h"
#include "Rts.h"
-#include "Storage.h"
-#include "MBlock.h"
+
#include "Evac.h"
+#include "Storage.h"
#include "GC.h"
+#include "GCThread.h"
#include "GCUtils.h"
#include "Compact.h"
#include "Prelude.h"
-#include "LdvProfile.h"
+#include "Trace.h"
-#if defined(PROF_SPIN) && defined(THREADED_RTS)
+#if defined(PROF_SPIN) && defined(THREADED_RTS) && defined(PARALLEL_GC)
StgWord64 whitehole_spin = 0;
#endif
+#if defined(THREADED_RTS) && !defined(PARALLEL_GC)
+#define evacuate(p) evacuate1(p)
+#define HEAP_ALLOCED_GC(p) HEAP_ALLOCED(p)
+#endif
+
+#if !defined(PARALLEL_GC)
+#define copy_tag_nolock(p, info, src, size, stp, tag) \
+ copy_tag(p, info, src, size, stp, tag)
+#endif
+
/* Used to avoid long recursion due to selector thunks
*/
#define MAX_THUNK_SELECTOR_DEPTH 16
* necessary.
*/
to = ws->todo_free;
- if (to + size > ws->todo_lim) {
+ ws->todo_free += size;
+ if (ws->todo_free > ws->todo_lim) {
to = todo_block_full(size, ws);
}
- ws->todo_free = to + size;
ASSERT(ws->todo_free >= ws->todo_bd->free && ws->todo_free <= ws->todo_lim);
return to;
The evacuate() code
-------------------------------------------------------------------------- */
-#define PARALLEL_GC
-#include "Evac.c-inc"
+STATIC_INLINE GNUC_ATTR_HOT void
+copy_tag(StgClosure **p, const StgInfoTable *info,
+ StgClosure *src, nat size, step *stp, StgWord tag)
+{
+ StgPtr to, from;
+ nat i;
+
+ to = alloc_for_copy(size,stp);
+
+ TICK_GC_WORDS_COPIED(size);
+
+ from = (StgPtr)src;
+ to[0] = (W_)info;
+ for (i = 1; i < size; i++) { // unroll for small i
+ to[i] = from[i];
+ }
+
+// if (to+size+2 < bd->start + BLOCK_SIZE_W) {
+// __builtin_prefetch(to + size + 2, 1);
+// }
+
+#if defined(PARALLEL_GC)
+ {
+ const StgInfoTable *new_info;
+ new_info = (const StgInfoTable *)cas((StgPtr)&src->header.info, (W_)info, MK_FORWARDING_PTR(to));
+ if (new_info != info) {
+ return evacuate(p); // does the failed_to_evac stuff
+ } else {
+ *p = TAG_CLOSURE(tag,(StgClosure*)to);
+ }
+ }
+#else
+ src->header.info = (const StgInfoTable *)MK_FORWARDING_PTR(to);
+ *p = TAG_CLOSURE(tag,(StgClosure*)to);
+#endif
+
+#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);
+#endif
+}
+
+#if defined(PARALLEL_GC)
+STATIC_INLINE void
+copy_tag_nolock(StgClosure **p, const StgInfoTable *info,
+ StgClosure *src, nat size, step *stp, StgWord tag)
+{
+ StgPtr to, from;
+ nat i;
+
+ to = alloc_for_copy(size,stp);
+ *p = TAG_CLOSURE(tag,(StgClosure*)to);
+ src->header.info = (const StgInfoTable *)MK_FORWARDING_PTR(to);
+
+ TICK_GC_WORDS_COPIED(size);
+
+ from = (StgPtr)src;
+ to[0] = (W_)info;
+ for (i = 1; i < size; i++) { // unroll for small i
+ to[i] = from[i];
+ }
+
+// if (to+size+2 < bd->start + BLOCK_SIZE_W) {
+// __builtin_prefetch(to + size + 2, 1);
+// }
+
+#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);
+#endif
+}
+#endif
+
+/* 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 rtsBool
+copyPart(StgClosure **p, StgClosure *src, nat size_to_reserve, nat size_to_copy, step *stp)
+{
+ StgPtr to, from;
+ nat i;
+ StgWord info;
+
+#if defined(PARALLEL_GC)
+spin:
+ info = xchg((StgPtr)&src->header.info, (W_)&stg_WHITEHOLE_info);
+ if (info == (W_)&stg_WHITEHOLE_info) {
+#ifdef PROF_SPIN
+ whitehole_spin++;
+#endif
+ goto spin;
+ }
+ if (IS_FORWARDING_PTR(info)) {
+ src->header.info = (const StgInfoTable *)info;
+ evacuate(p); // does the failed_to_evac stuff
+ return rtsFalse;
+ }
+#else
+ info = (W_)src->header.info;
+#endif
+
+ to = alloc_for_copy(size_to_reserve, stp);
+ *p = (StgClosure *)to;
+
+ TICK_GC_WORDS_COPIED(size_to_copy);
+
+ from = (StgPtr)src;
+ to[0] = info;
+ for (i = 1; i < size_to_copy; i++) { // unroll for small i
+ to[i] = from[i];
+ }
+
+#if defined(PARALLEL_GC)
+ write_barrier();
+#endif
+ src->header.info = (const StgInfoTable*)MK_FORWARDING_PTR(to);
+
+#ifdef PROFILING
+ // We store the size of the just evacuated object in the LDV word so that
+ // the profiler can guess the position of the next object later.
+ SET_EVACUAEE_FOR_LDV(from, size_to_reserve);
+ // fill the slop
+ if (size_to_reserve - size_to_copy > 0)
+ LDV_FILL_SLOP(to + size_to_copy, (int)(size_to_reserve - size_to_copy));
+#endif
+
+ return rtsTrue;
+}
-#undef PARALLEL_GC
-#include "Evac.c-inc"
+
+/* Copy wrappers that don't tag the closure after copying */
+STATIC_INLINE GNUC_ATTR_HOT void
+copy(StgClosure **p, const StgInfoTable *info,
+ StgClosure *src, nat size, step *stp)
+{
+ copy_tag(p,info,src,size,stp,0);
+}
/* -----------------------------------------------------------------------------
Evacuate a large object
stp = bd->step;
ACQUIRE_SPIN_LOCK(&stp->sync_large_objects);
- // object must be at the beginning of the block (or be a ByteArray)
- ASSERT(get_itbl((StgClosure *)p)->type == ARR_WORDS ||
- (((W_)p & BLOCK_MASK) == 0));
-
// already evacuated?
if (bd->flags & BF_EVACUATED) {
/* Don't forget to set the gct->failed_to_evac flag if we didn't get
}
ws = &gct->steps[new_stp->abs_no];
+
bd->flags |= BF_EVACUATED;
bd->step = new_stp;
bd->gen_no = new_stp->gen_no;
- bd->link = ws->todo_large_objects;
- ws->todo_large_objects = bd;
+
+ // If this is a block of pinned objects, we don't have to scan
+ // these objects, because they aren't allowed to contain any
+ // pointers. For these blocks, we skip the scavenge stage and put
+ // them straight on the scavenged_large_objects list.
+ if (bd->flags & BF_PINNED) {
+ ASSERT(get_itbl((StgClosure *)p)->type == ARR_WORDS);
+ if (new_stp != stp) { ACQUIRE_SPIN_LOCK(&new_stp->sync_large_objects); }
+ dbl_link_onto(bd, &new_stp->scavenged_large_objects);
+ new_stp->n_scavenged_large_blocks += bd->blocks;
+ if (new_stp != stp) { RELEASE_SPIN_LOCK(&new_stp->sync_large_objects); }
+ } else {
+ bd->link = ws->todo_large_objects;
+ ws->todo_large_objects = bd;
+ }
RELEASE_SPIN_LOCK(&stp->sync_large_objects);
}
+/* ----------------------------------------------------------------------------
+ Evacuate
+
+ This is called (eventually) for every live object in the system.
+
+ The caller to evacuate specifies a desired generation in the
+ gct->evac_step thread-local variable. The following conditions apply to
+ evacuating an object which resides in generation M when we're
+ collecting up to generation N
+
+ if M >= gct->evac_step
+ if M > N do nothing
+ else evac to step->to
+
+ if M < gct->evac_step evac to gct->evac_step, step 0
+
+ if the object is already evacuated, then we check which generation
+ it now resides in.
+
+ if M >= gct->evac_step do nothing
+ if M < gct->evac_step set gct->failed_to_evac flag to indicate that we
+ didn't manage to evacuate this object into gct->evac_step.
+
+
+ OPTIMISATION NOTES:
+
+ evacuate() is the single most important function performance-wise
+ in the GC. Various things have been tried to speed it up, but as
+ far as I can tell the code generated by gcc 3.2 with -O2 is about
+ as good as it's going to get. We pass the argument to evacuate()
+ in a register using the 'regparm' attribute (see the prototype for
+ evacuate() near the top of this file).
+
+ Changing evacuate() to take an (StgClosure **) rather than
+ returning the new pointer seems attractive, because we can avoid
+ writing back the pointer when it hasn't changed (eg. for a static
+ object, or an object in a generation > N). However, I tried it and
+ it doesn't help. One reason is that the (StgClosure **) pointer
+ gets spilled to the stack inside evacuate(), resulting in far more
+ extra reads/writes than we save.
+ ------------------------------------------------------------------------- */
+
+REGPARM1 GNUC_ATTR_HOT void
+evacuate(StgClosure **p)
+{
+ bdescr *bd = NULL;
+ step *stp;
+ StgClosure *q;
+ const StgInfoTable *info;
+ StgWord tag;
+
+ q = *p;
+
+loop:
+ /* The tag and the pointer are split, to be merged after evacing */
+ tag = GET_CLOSURE_TAG(q);
+ q = UNTAG_CLOSURE(q);
+
+ ASSERT(LOOKS_LIKE_CLOSURE_PTR(q));
+
+ if (!HEAP_ALLOCED_GC(q)) {
+
+ if (!major_gc) return;
+
+ info = get_itbl(q);
+ switch (info->type) {
+
+ case THUNK_STATIC:
+ if (info->srt_bitmap != 0) {
+ if (*THUNK_STATIC_LINK((StgClosure *)q) == NULL) {
+#ifndef THREADED_RTS
+ *THUNK_STATIC_LINK((StgClosure *)q) = gct->static_objects;
+ gct->static_objects = (StgClosure *)q;
+#else
+ StgPtr link;
+ link = (StgPtr)cas((StgPtr)THUNK_STATIC_LINK((StgClosure *)q),
+ (StgWord)NULL,
+ (StgWord)gct->static_objects);
+ if (link == NULL) {
+ gct->static_objects = (StgClosure *)q;
+ }
+#endif
+ }
+ }
+ return;
+
+ case FUN_STATIC:
+ if (info->srt_bitmap != 0 &&
+ *FUN_STATIC_LINK((StgClosure *)q) == NULL) {
+#ifndef THREADED_RTS
+ *FUN_STATIC_LINK((StgClosure *)q) = gct->static_objects;
+ gct->static_objects = (StgClosure *)q;
+#else
+ StgPtr link;
+ link = (StgPtr)cas((StgPtr)FUN_STATIC_LINK((StgClosure *)q),
+ (StgWord)NULL,
+ (StgWord)gct->static_objects);
+ if (link == NULL) {
+ gct->static_objects = (StgClosure *)q;
+ }
+#endif
+ }
+ return;
+
+ 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) {
+ if (*IND_STATIC_LINK((StgClosure *)q) == NULL) {
+#ifndef THREADED_RTS
+ *IND_STATIC_LINK((StgClosure *)q) = gct->static_objects;
+ gct->static_objects = (StgClosure *)q;
+#else
+ StgPtr link;
+ link = (StgPtr)cas((StgPtr)IND_STATIC_LINK((StgClosure *)q),
+ (StgWord)NULL,
+ (StgWord)gct->static_objects);
+ if (link == NULL) {
+ gct->static_objects = (StgClosure *)q;
+ }
+#endif
+ }
+ }
+ return;
+
+ case CONSTR_STATIC:
+ if (*STATIC_LINK(info,(StgClosure *)q) == NULL) {
+#ifndef THREADED_RTS
+ *STATIC_LINK(info,(StgClosure *)q) = gct->static_objects;
+ gct->static_objects = (StgClosure *)q;
+#else
+ StgPtr link;
+ link = (StgPtr)cas((StgPtr)STATIC_LINK(info,(StgClosure *)q),
+ (StgWord)NULL,
+ (StgWord)gct->static_objects);
+ if (link == NULL) {
+ gct->static_objects = (StgClosure *)q;
+ }
+#endif
+ }
+ /* I am assuming that static_objects pointers are not
+ * written to other objects, and thus, no need to retag. */
+ return;
+
+ case CONSTR_NOCAF_STATIC:
+ /* no need to put these on the static linked list, they don't need
+ * to be scavenged.
+ */
+ return;
+
+ default:
+ barf("evacuate(static): strange closure type %d", (int)(info->type));
+ }
+ }
+
+ bd = Bdescr((P_)q);
+
+ if ((bd->flags & (BF_LARGE | BF_MARKED | BF_EVACUATED)) != 0) {
+
+ // pointer into to-space: just return it. It might be a pointer
+ // into a generation that we aren't collecting (> N), or it
+ // might just be a pointer into to-space. The latter doesn't
+ // happen often, but allowing it makes certain things a bit
+ // easier; e.g. scavenging an object is idempotent, so it's OK to
+ // have an object on the mutable list multiple times.
+ if (bd->flags & BF_EVACUATED) {
+ // We aren't copying this object, so we have to check
+ // whether it is already in the target generation. (this is
+ // the write barrier).
+ if (bd->step < gct->evac_step) {
+ gct->failed_to_evac = rtsTrue;
+ TICK_GC_FAILED_PROMOTION();
+ }
+ return;
+ }
+
+ /* 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;
+ *p = q;
+ goto loop;
+ }
+ evacuate_large((P_)q);
+ return;
+ }
+
+ /* If the object is in a step that we're compacting, then we
+ * need to use an alternative evacuate procedure.
+ */
+ if (!is_marked((P_)q,bd)) {
+ mark((P_)q,bd);
+ if (mark_stack_full()) {
+ debugTrace(DEBUG_gc,"mark stack overflowed");
+ mark_stack_overflowed = rtsTrue;
+ reset_mark_stack();
+ }
+ push_mark_stack((P_)q);
+ }
+ return;
+ }
+
+ stp = bd->step->to;
+
+ info = q->header.info;
+ if (IS_FORWARDING_PTR(info))
+ {
+ /* Already evacuated, just return the forwarding address.
+ * HOWEVER: if the requested destination generation (gct->evac_step) is
+ * older than the actual generation (because the object was
+ * already evacuated to a younger generation) then we have to
+ * set the gct->failed_to_evac flag to indicate that we couldn't
+ * manage to promote the object to the desired generation.
+ */
+ /*
+ * Optimisation: the check is fairly expensive, but we can often
+ * shortcut it if either the required generation is 0, or the
+ * current object (the EVACUATED) is in a high enough generation.
+ * We know that an EVACUATED always points to an object in the
+ * same or an older generation. stp is the lowest step that the
+ * current object would be evacuated to, so we only do the full
+ * check if stp is too low.
+ */
+ StgClosure *e = (StgClosure*)UN_FORWARDING_PTR(info);
+ *p = TAG_CLOSURE(tag,e);
+ if (stp < gct->evac_step) { // optimisation
+ if (Bdescr((P_)e)->step < gct->evac_step) {
+ gct->failed_to_evac = rtsTrue;
+ TICK_GC_FAILED_PROMOTION();
+ }
+ }
+ return;
+ }
+
+ switch (INFO_PTR_TO_STRUCT(info)->type) {
+
+ case WHITEHOLE:
+ goto loop;
+
+ case MUT_VAR_CLEAN:
+ case MUT_VAR_DIRTY:
+ case MVAR_CLEAN:
+ case MVAR_DIRTY:
+ copy(p,info,q,sizeW_fromITBL(INFO_PTR_TO_STRUCT(info)),stp);
+ return;
+
+ case CONSTR_0_1:
+ {
+ StgWord w = (StgWord)q->payload[0];
+ if (info == Czh_con_info &&
+ // unsigned, so always true: (StgChar)w >= MIN_CHARLIKE &&
+ (StgChar)w <= MAX_CHARLIKE) {
+ *p = TAG_CLOSURE(tag,
+ (StgClosure *)CHARLIKE_CLOSURE((StgChar)w)
+ );
+ }
+ else if (info == Izh_con_info &&
+ (StgInt)w >= MIN_INTLIKE && (StgInt)w <= MAX_INTLIKE) {
+ *p = TAG_CLOSURE(tag,
+ (StgClosure *)INTLIKE_CLOSURE((StgInt)w)
+ );
+ }
+ else {
+ copy_tag_nolock(p,info,q,sizeofW(StgHeader)+1,stp,tag);
+ }
+ return;
+ }
+
+ case FUN_0_1:
+ case FUN_1_0:
+ case CONSTR_1_0:
+ copy_tag_nolock(p,info,q,sizeofW(StgHeader)+1,stp,tag);
+ return;
+
+ case THUNK_1_0:
+ case THUNK_0_1:
+ copy(p,info,q,sizeofW(StgThunk)+1,stp);
+ return;
+
+ case THUNK_1_1:
+ case THUNK_2_0:
+ case THUNK_0_2:
+#ifdef NO_PROMOTE_THUNKS
+ if (bd->gen_no == 0 &&
+ bd->step->no != 0 &&
+ bd->step->no == generations[bd->gen_no].n_steps-1) {
+ stp = bd->step;
+ }
+#endif
+ copy(p,info,q,sizeofW(StgThunk)+2,stp);
+ return;
+
+ case FUN_1_1:
+ case FUN_2_0:
+ case FUN_0_2:
+ case CONSTR_1_1:
+ case CONSTR_2_0:
+ copy_tag_nolock(p,info,q,sizeofW(StgHeader)+2,stp,tag);
+ return;
+
+ case CONSTR_0_2:
+ copy_tag_nolock(p,info,q,sizeofW(StgHeader)+2,stp,tag);
+ return;
+
+ case THUNK:
+ copy(p,info,q,thunk_sizeW_fromITBL(INFO_PTR_TO_STRUCT(info)),stp);
+ return;
+
+ case FUN:
+ case IND_PERM:
+ case IND_OLDGEN_PERM:
+ case CONSTR:
+ copy_tag_nolock(p,info,q,sizeW_fromITBL(INFO_PTR_TO_STRUCT(info)),stp,tag);
+ return;
+
+ case WEAK:
+ case STABLE_NAME:
+ copy_tag(p,info,q,sizeW_fromITBL(INFO_PTR_TO_STRUCT(info)),stp,tag);
+ return;
+
+ case BCO:
+ copy(p,info,q,bco_sizeW((StgBCO *)q),stp);
+ return;
+
+ case CAF_BLACKHOLE:
+ case BLACKHOLE:
+ copyPart(p,q,BLACKHOLE_sizeW(),sizeofW(StgHeader),stp);
+ return;
+
+ case THUNK_SELECTOR:
+ eval_thunk_selector(p, (StgSelector *)q, rtsTrue);
+ return;
+
+ case IND:
+ case IND_OLDGEN:
+ // follow chains of indirections, don't evacuate them
+ q = ((StgInd*)q)->indirectee;
+ *p = q;
+ goto loop;
+
+ case RET_BCO:
+ case RET_SMALL:
+ case RET_BIG:
+ case RET_DYN:
+ case UPDATE_FRAME:
+ case STOP_FRAME:
+ case CATCH_FRAME:
+ case CATCH_STM_FRAME:
+ case CATCH_RETRY_FRAME:
+ case ATOMICALLY_FRAME:
+ // shouldn't see these
+ barf("evacuate: stack frame at %p\n", q);
+
+ case PAP:
+ copy(p,info,q,pap_sizeW((StgPAP*)q),stp);
+ return;
+
+ case AP:
+ copy(p,info,q,ap_sizeW((StgAP*)q),stp);
+ return;
+
+ case AP_STACK:
+ copy(p,info,q,ap_stack_sizeW((StgAP_STACK*)q),stp);
+ return;
+
+ case ARR_WORDS:
+ // just copy the block
+ copy(p,info,q,arr_words_sizeW((StgArrWords *)q),stp);
+ return;
+
+ case MUT_ARR_PTRS_CLEAN:
+ case MUT_ARR_PTRS_DIRTY:
+ case MUT_ARR_PTRS_FROZEN:
+ case MUT_ARR_PTRS_FROZEN0:
+ // just copy the block
+ copy(p,info,q,mut_arr_ptrs_sizeW((StgMutArrPtrs *)q),stp);
+ return;
+
+ case TSO:
+ {
+ StgTSO *tso = (StgTSO *)q;
+
+ /* Deal with redirected TSOs (a TSO that's had its stack enlarged).
+ */
+ if (tso->what_next == ThreadRelocated) {
+ q = (StgClosure *)tso->_link;
+ *p = q;
+ goto loop;
+ }
+
+ /* To evacuate a small TSO, we need to relocate the update frame
+ * list it contains.
+ */
+ {
+ StgTSO *new_tso;
+ StgPtr r, s;
+ rtsBool mine;
+
+ mine = copyPart(p,(StgClosure *)tso, tso_sizeW(tso),
+ sizeofW(StgTSO), stp);
+ if (mine) {
+ new_tso = (StgTSO *)*p;
+ move_TSO(tso, new_tso);
+ for (r = tso->sp, s = new_tso->sp;
+ r < tso->stack+tso->stack_size;) {
+ *s++ = *r++;
+ }
+ }
+ return;
+ }
+ }
+
+ case TREC_HEADER:
+ copy(p,info,q,sizeofW(StgTRecHeader),stp);
+ return;
+
+ case TVAR_WATCH_QUEUE:
+ copy(p,info,q,sizeofW(StgTVarWatchQueue),stp);
+ return;
+
+ case TVAR:
+ copy(p,info,q,sizeofW(StgTVar),stp);
+ return;
+
+ case TREC_CHUNK:
+ copy(p,info,q,sizeofW(StgTRecChunk),stp);
+ return;
+
+ case ATOMIC_INVARIANT:
+ copy(p,info,q,sizeofW(StgAtomicInvariant),stp);
+ return;
+
+ case INVARIANT_CHECK_QUEUE:
+ copy(p,info,q,sizeofW(StgInvariantCheckQueue),stp);
+ return;
+
+ default:
+ barf("evacuate: strange closure type %d", (int)(INFO_PTR_TO_STRUCT(info)->type));
+ }
+
+ barf("evacuate");
+}
+
/* -----------------------------------------------------------------------------
Evaluate a THUNK_SELECTOR if possible.
// invoke eval_thunk_selector(), the recursive calls will not
// evacuate the value (because we want to select on the value,
// not evacuate it), so in this case val is in from-space.
- // ASSERT(!HEAP_ALLOCED(val) || Bdescr((P_)val)->gen_no > N || (Bdescr((P_)val)->flags & BF_EVACUATED));
+ // ASSERT(!HEAP_ALLOCED_GC(val) || Bdescr((P_)val)->gen_no > N || (Bdescr((P_)val)->flags & BF_EVACUATED));
prev = (StgSelector*)((StgClosure *)p)->payload[0];
// 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).
- ((StgInd *)p)->indirectee = val;
- write_barrier();
- SET_INFO(p, &stg_IND_info);
+ // value. The value is still in from-space at this stage.
+ //
+ // (old note: Why not do 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).
+ if ((StgClosure *)p == val) {
+ // must be a loop; just leave a BLACKHOLE in place. This
+ // can happen when we have a chain of selectors that
+ // eventually loops back on itself. We can't leave an
+ // indirection pointing to itself, and we want the program
+ // to deadlock if it ever enters this closure, so
+ // BLACKHOLE is correct.
+ SET_INFO(p, &stg_BLACKHOLE_info);
+ } else {
+ ((StgInd *)p)->indirectee = val;
+ write_barrier();
+ SET_INFO(p, &stg_IND_info);
+ }
// For the purposes of LDV profiling, we have created an
// indirection.
selector_chain:
bd = Bdescr((StgPtr)p);
- if (HEAP_ALLOCED(p)) {
+ if (HEAP_ALLOCED_GC(p)) {
// If the THUNK_SELECTOR is in to-space or in a generation that we
// are not collecting, then bale out early. We won't be able to
// save any space in any case, and updating with an indirection is
// trickier in a non-collected gen: we would have to update the
// mutable list.
- if ((bd->gen_no > N) || (bd->flags & BF_EVACUATED)) {
+ if (bd->flags & BF_EVACUATED) {
unchain_thunk_selectors(prev_thunk_selector, (StgClosure *)p);
*q = (StgClosure *)p;
+ // shortcut, behave as for: if (evac) evacuate(q);
+ if (evac && bd->step < gct->evac_step) {
+ gct->failed_to_evac = rtsTrue;
+ TICK_GC_FAILED_PROMOTION();
+ }
return;
}
// we don't update THUNK_SELECTORS in the compacted
// (scavenge_mark_stack doesn't deal with IND). BEWARE! This
// bit is very tricky to get right. If you make changes
// around here, test by compiling stage 3 with +RTS -c -RTS.
- if (bd->flags & BF_COMPACTED) {
+ if (bd->flags & BF_MARKED) {
// must call evacuate() to mark this closure if evac==rtsTrue
*q = (StgClosure *)p;
if (evac) evacuate(q);
} while (info_ptr == (W_)&stg_WHITEHOLE_info);
// make sure someone else didn't get here first...
- if (INFO_PTR_TO_STRUCT(info_ptr)->type != THUNK_SELECTOR) {
+ if (IS_FORWARDING_PTR(p) ||
+ INFO_PTR_TO_STRUCT(info_ptr)->type != THUNK_SELECTOR) {
// v. tricky now. The THUNK_SELECTOR has been evacuated
- // by another thread, and is now either EVACUATED or IND.
+ // by another thread, and is now either a forwarding ptr or IND.
// We need to extract ourselves from the current situation
// as cleanly as possible.
// - unlock the closure
// from-space during marking, for example. We rely on the property
// that evacuate() doesn't mind if it gets passed a to-space pointer.
- info = get_itbl(selectee);
+ info = (StgInfoTable*)selectee->header.info;
+
+ if (IS_FORWARDING_PTR(info)) {
+ // 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.
+ goto bale_out;
+ }
+
+ info = INFO_PTR_TO_STRUCT(info);
switch (info->type) {
case WHITEHOLE:
goto bale_out; // about to be evacuated by another thread (or a loop).
// the original selector thunk, p.
SET_INFO(p, (StgInfoTable *)info_ptr);
LDV_RECORD_DEAD_FILL_SLOP_DYNAMIC((StgClosure *)p);
+#if defined(THREADED_RTS)
+ SET_INFO(p, &stg_WHITEHOLE_info);
+#else
SET_INFO(p, &stg_BLACKHOLE_info);
#endif
+#endif
// the closure in val is now the "value" of the
// THUNK_SELECTOR in p. However, val may itself be a
// evaluating until we find the real value, and then
// update the whole chain to point to the value.
val_loop:
- info = get_itbl(UNTAG_CLOSURE(val));
- switch (info->type) {
- case IND:
- case IND_PERM:
- case IND_OLDGEN:
- case IND_OLDGEN_PERM:
- case IND_STATIC:
- val = ((StgInd *)val)->indirectee;
- goto val_loop;
- case THUNK_SELECTOR:
- ((StgClosure*)p)->payload[0] = (StgClosure *)prev_thunk_selector;
- prev_thunk_selector = p;
- p = (StgSelector*)val;
- goto selector_chain;
- default:
- ((StgClosure*)p)->payload[0] = (StgClosure *)prev_thunk_selector;
- prev_thunk_selector = p;
-
- *q = val;
- if (evac) evacuate(q);
- val = *q;
- // evacuate() cannot recurse through
- // eval_thunk_selector(), because we know val is not
- // a THUNK_SELECTOR.
- unchain_thunk_selectors(prev_thunk_selector, val);
- return;
+ info_ptr = (StgWord)UNTAG_CLOSURE(val)->header.info;
+ if (!IS_FORWARDING_PTR(info_ptr))
+ {
+ info = INFO_PTR_TO_STRUCT(info_ptr);
+ switch (info->type) {
+ case IND:
+ case IND_PERM:
+ case IND_OLDGEN:
+ case IND_OLDGEN_PERM:
+ case IND_STATIC:
+ val = ((StgInd *)val)->indirectee;
+ goto val_loop;
+ case THUNK_SELECTOR:
+ ((StgClosure*)p)->payload[0] = (StgClosure *)prev_thunk_selector;
+ prev_thunk_selector = p;
+ p = (StgSelector*)val;
+ goto selector_chain;
+ default:
+ break;
+ }
}
+ ((StgClosure*)p)->payload[0] = (StgClosure *)prev_thunk_selector;
+ prev_thunk_selector = p;
+
+ *q = val;
+
+ // update the other selectors in the chain *before*
+ // evacuating the value. This is necessary in the case
+ // where the value turns out to be one of the selectors
+ // in the chain (i.e. we have a loop), and evacuating it
+ // would corrupt the chain.
+ unchain_thunk_selectors(prev_thunk_selector, val);
+
+ // evacuate() cannot recurse through
+ // eval_thunk_selector(), because we know val is not
+ // a THUNK_SELECTOR.
+ if (evac) evacuate(q);
+ return;
}
case IND:
selectee = UNTAG_CLOSURE( ((StgInd *)selectee)->indirectee );
goto selector_loop;
- case EVACUATED:
- // We don't follow pointers into to-space; the constructor
- // has already been evacuated, so we won't save any space
- // leaks by evaluating this selector thunk anyhow.
- goto bale_out;
-
case THUNK_SELECTOR:
{
StgClosure *val;
case THUNK_0_2:
case THUNK_STATIC:
case CAF_BLACKHOLE:
- case SE_CAF_BLACKHOLE:
- case SE_BLACKHOLE:
case BLACKHOLE:
// not evaluated yet
goto bale_out;
// check whether it was updated in the meantime.
*q = (StgClosure *)p;
if (evac) {
- copy(q,(StgClosure *)p,THUNK_SELECTOR_sizeW(),bd->step->to);
+ copy(q,(const StgInfoTable *)info_ptr,(StgClosure *)p,THUNK_SELECTOR_sizeW(),bd->step->to);
}
unchain_thunk_selectors(prev_thunk_selector, *q);
return;
}
-
-/* -----------------------------------------------------------------------------
- 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;
-}
-
projects / ghc-hetmet.git / blobdiff