diff options
Diffstat (limited to 'js/src/gc')
32 files changed, 1953 insertions, 888 deletions
diff --git a/js/src/gc/Allocator.cpp b/js/src/gc/Allocator.cpp index c070ac1eef..9e7f16cc3f 100644 --- a/js/src/gc/Allocator.cpp +++ b/js/src/gc/Allocator.cpp @@ -77,9 +77,10 @@ MOZ_NEVER_INLINE void* CellAllocator::RetryNurseryAlloc(JSContext* cx, size_t thingSize, AllocSite* site) { MOZ_ASSERT(cx->isNurseryAllocAllowed()); - MOZ_ASSERT(cx->zone() == site->zone()); - MOZ_ASSERT(!cx->zone()->isAtomsZone()); - MOZ_ASSERT(cx->zone()->allocKindInNursery(traceKind)); + + Zone* zone = site->zone(); + MOZ_ASSERT(!zone->isAtomsZone()); + MOZ_ASSERT(zone->allocKindInNursery(traceKind)); Nursery& nursery = cx->nursery(); JS::GCReason reason = nursery.handleAllocationFailure(); @@ -102,7 +103,7 @@ MOZ_NEVER_INLINE void* CellAllocator::RetryNurseryAlloc(JSContext* cx, cx->runtime()->gc.minorGC(reason); // Exceeding gcMaxBytes while tenuring can disable the Nursery. - if (cx->zone()->allocKindInNursery(traceKind)) { + if (zone->allocKindInNursery(traceKind)) { void* ptr = cx->nursery().allocateCell(site, thingSize, traceKind); if (ptr) { return ptr; @@ -291,7 +292,7 @@ void CellAllocator::CheckIncrementalZoneState(JSContext* cx, void* ptr) { } #endif -void* js::gc::AllocateCellInGC(Zone* zone, AllocKind thingKind) { +void* js::gc::AllocateTenuredCellInGC(Zone* zone, AllocKind thingKind) { void* ptr = zone->arenas.allocateFromFreeList(thingKind); if (!ptr) { AutoEnterOOMUnsafeRegion oomUnsafe; @@ -541,7 +542,7 @@ TenuredChunk* GCRuntime::getOrAllocChunk(AutoLockGCBgAlloc& lock) { // Reinitialize ChunkBase; arenas are all free and may or may not be // committed. SetMemCheckKind(chunk, sizeof(ChunkBase), MemCheckKind::MakeUndefined); - chunk->initBase(rt, nullptr); + chunk->initBaseForTenuredChunk(rt); MOZ_ASSERT(chunk->unused()); } else { void* ptr = TenuredChunk::allocate(this); diff --git a/js/src/gc/Allocator.h b/js/src/gc/Allocator.h index 3b1566e7f5..c317bfb10b 100644 --- a/js/src/gc/Allocator.h +++ b/js/src/gc/Allocator.h @@ -21,6 +21,7 @@ namespace gc { class AllocSite; struct Cell; class TenuredCell; +class TenuringTracer; // Allocator implementation functions. SpiderMonkey code outside this file // should use: @@ -82,6 +83,7 @@ class CellAllocator { static void* AllocNurseryOrTenuredCell(JSContext* cx, gc::AllocKind allocKind, size_t thingSize, gc::Heap heap, AllocSite* site); + friend class TenuringTracer; // Allocate a cell in the tenured heap. template <AllowGC allowGC> diff --git a/js/src/gc/AtomMarking.cpp b/js/src/gc/AtomMarking.cpp index eb30758263..a5b7eb1acf 100644 --- a/js/src/gc/AtomMarking.cpp +++ b/js/src/gc/AtomMarking.cpp @@ -12,6 +12,7 @@ #include "gc/GC-inl.h" #include "gc/Heap-inl.h" +#include "gc/PrivateIterators-inl.h" namespace js { namespace gc { @@ -71,7 +72,38 @@ void AtomMarkingRuntime::unregisterArena(Arena* arena, const AutoLockGC& lock) { (void)freeArenaIndexes.ref().emplaceBack(arena->atomBitmapStart()); } -bool AtomMarkingRuntime::computeBitmapFromChunkMarkBits(JSRuntime* runtime, +void AtomMarkingRuntime::refineZoneBitmapsForCollectedZones( + GCRuntime* gc, size_t collectedZones) { + // If there is more than one zone to update, copy the chunk mark bits into a + // bitmap and AND that into the atom marking bitmap for each zone. + DenseBitmap marked; + if (collectedZones > 1 && computeBitmapFromChunkMarkBits(gc, marked)) { + for (GCZonesIter zone(gc); !zone.done(); zone.next()) { + refineZoneBitmapForCollectedZone(zone, marked); + } + return; + } + + // If there's only one zone (or on OOM), AND the mark bits for each arena into + // the zones' atom marking bitmaps directly. + for (GCZonesIter zone(gc); !zone.done(); zone.next()) { + if (zone->isAtomsZone()) { + continue; + } + + for (auto thingKind : AllAllocKinds()) { + for (ArenaIterInGC aiter(gc->atomsZone(), thingKind); !aiter.done(); + aiter.next()) { + Arena* arena = aiter.get(); + MarkBitmapWord* chunkWords = arena->chunk()->markBits.arenaBits(arena); + zone->markedAtoms().bitwiseAndRangeWith(arena->atomBitmapStart(), + ArenaBitmapWords, chunkWords); + } + } + } +} + +bool AtomMarkingRuntime::computeBitmapFromChunkMarkBits(GCRuntime* gc, DenseBitmap& bitmap) { MOZ_ASSERT(CurrentThreadIsPerformingGC()); @@ -79,7 +111,7 @@ bool AtomMarkingRuntime::computeBitmapFromChunkMarkBits(JSRuntime* runtime, return false; } - Zone* atomsZone = runtime->unsafeAtomsZone(); + Zone* atomsZone = gc->atomsZone(); for (auto thingKind : AllAllocKinds()) { for (ArenaIterInGC aiter(atomsZone, thingKind); !aiter.done(); aiter.next()) { @@ -109,13 +141,12 @@ void AtomMarkingRuntime::refineZoneBitmapForCollectedZone( // Set any bits in the chunk mark bitmaps for atoms which are marked in bitmap. template <typename Bitmap> -static void BitwiseOrIntoChunkMarkBits(JSRuntime* runtime, Bitmap& bitmap) { +static void BitwiseOrIntoChunkMarkBits(Zone* atomsZone, Bitmap& bitmap) { // Make sure that by copying the mark bits for one arena in word sizes we // do not affect the mark bits for other arenas. static_assert(ArenaBitmapBits == ArenaBitmapWords * JS_BITS_PER_WORD, "ArenaBitmapWords must evenly divide ArenaBitmapBits"); - Zone* atomsZone = runtime->unsafeAtomsZone(); for (auto thingKind : AllAllocKinds()) { for (ArenaIterInGC aiter(atomsZone, thingKind); !aiter.done(); aiter.next()) { @@ -127,16 +158,10 @@ static void BitwiseOrIntoChunkMarkBits(JSRuntime* runtime, Bitmap& bitmap) { } } -void AtomMarkingRuntime::markAtomsUsedByUncollectedZones(JSRuntime* runtime) { +void AtomMarkingRuntime::markAtomsUsedByUncollectedZones( + GCRuntime* gc, size_t uncollectedZones) { MOZ_ASSERT(CurrentThreadIsPerformingGC()); - size_t uncollectedZones = 0; - for (ZonesIter zone(runtime, SkipAtoms); !zone.done(); zone.next()) { - if (!zone->isCollecting()) { - uncollectedZones++; - } - } - // If there are no uncollected non-atom zones then there's no work to do. if (uncollectedZones == 0) { return; @@ -149,15 +174,15 @@ void AtomMarkingRuntime::markAtomsUsedByUncollectedZones(JSRuntime* runtime) { DenseBitmap markedUnion; if (uncollectedZones == 1 || !markedUnion.ensureSpace(allocatedWords)) { - for (ZonesIter zone(runtime, SkipAtoms); !zone.done(); zone.next()) { + for (ZonesIter zone(gc, SkipAtoms); !zone.done(); zone.next()) { if (!zone->isCollecting()) { - BitwiseOrIntoChunkMarkBits(runtime, zone->markedAtoms()); + BitwiseOrIntoChunkMarkBits(gc->atomsZone(), zone->markedAtoms()); } } return; } - for (ZonesIter zone(runtime, SkipAtoms); !zone.done(); zone.next()) { + for (ZonesIter zone(gc, SkipAtoms); !zone.done(); zone.next()) { // We only need to update the chunk mark bits for zones which were // not collected in the current GC. Atoms which are referenced by // collected zones have already been marked. @@ -166,7 +191,7 @@ void AtomMarkingRuntime::markAtomsUsedByUncollectedZones(JSRuntime* runtime) { } } - BitwiseOrIntoChunkMarkBits(runtime, markedUnion); + BitwiseOrIntoChunkMarkBits(gc->atomsZone(), markedUnion); } template <typename T> diff --git a/js/src/gc/AtomMarking.h b/js/src/gc/AtomMarking.h index e7e97fb389..e5d8ef8418 100644 --- a/js/src/gc/AtomMarking.h +++ b/js/src/gc/AtomMarking.h @@ -19,6 +19,7 @@ class DenseBitmap; namespace gc { class Arena; +class GCRuntime; // This class manages state used for marking atoms during GCs. // See AtomMarking.cpp for details. @@ -42,19 +43,25 @@ class AtomMarkingRuntime { // Mark an arena as no longer holding things in the atoms zone. void unregisterArena(Arena* arena, const AutoLockGC& lock); + // Update the atom marking bitmaps in all collected zones according to the + // atoms zone mark bits. + void refineZoneBitmapsForCollectedZones(GCRuntime* gc, size_t collectedZones); + + // Set any bits in the chunk mark bitmaps for atoms which are marked in any + // uncollected zone in the runtime. + void markAtomsUsedByUncollectedZones(GCRuntime* gc, size_t uncollectedZones); + + private: // Fill |bitmap| with an atom marking bitmap based on the things that are // currently marked in the chunks used by atoms zone arenas. This returns // false on an allocation failure (but does not report an exception). - bool computeBitmapFromChunkMarkBits(JSRuntime* runtime, DenseBitmap& bitmap); + bool computeBitmapFromChunkMarkBits(GCRuntime* gc, DenseBitmap& bitmap); // Update the atom marking bitmap in |zone| according to another // overapproximation of the reachable atoms in |bitmap|. void refineZoneBitmapForCollectedZone(Zone* zone, const DenseBitmap& bitmap); - // Set any bits in the chunk mark bitmaps for atoms which are marked in any - // uncollected zone in the runtime. - void markAtomsUsedByUncollectedZones(JSRuntime* runtime); - + public: // Mark an atom or id as being newly reachable by the context's zone. template <typename T> void markAtom(JSContext* cx, T* thing); diff --git a/js/src/gc/Cell.h b/js/src/gc/Cell.h index 5a89ad794d..f91163e2f5 100644 --- a/js/src/gc/Cell.h +++ b/js/src/gc/Cell.h @@ -209,6 +209,8 @@ struct Cell { inline JS::Zone* nurseryZone() const; inline JS::Zone* nurseryZoneFromAnyThread() const; + inline ChunkBase* chunk() const; + // Default implementation for kinds that cannot be permanent. This may be // overriden by derived classes. MOZ_ALWAYS_INLINE bool isPermanentAndMayBeShared() const { return false; } @@ -222,7 +224,6 @@ struct Cell { protected: uintptr_t address() const; - inline ChunkBase* chunk() const; private: // Cells are destroyed by the GC. Do not delete them directly. diff --git a/js/src/gc/Compacting.cpp b/js/src/gc/Compacting.cpp index 442fa3fe47..79e8e0b71d 100644 --- a/js/src/gc/Compacting.cpp +++ b/js/src/gc/Compacting.cpp @@ -215,7 +215,7 @@ static void RelocateCell(Zone* zone, TenuredCell* src, AllocKind thingKind, // Allocate a new cell. MOZ_ASSERT(zone == src->zone()); TenuredCell* dst = - reinterpret_cast<TenuredCell*>(AllocateCellInGC(zone, thingKind)); + reinterpret_cast<TenuredCell*>(AllocateTenuredCellInGC(zone, thingKind)); // Copy source cell contents to destination. memcpy(dst, src, thingSize); diff --git a/js/src/gc/GC.cpp b/js/src/gc/GC.cpp index c01dfe3660..68dd66898c 100644 --- a/js/src/gc/GC.cpp +++ b/js/src/gc/GC.cpp @@ -444,7 +444,9 @@ GCRuntime::GCRuntime(JSRuntime* rt) #endif requestSliceAfterBackgroundTask(false), lifoBlocksToFree((size_t)JSContext::TEMP_LIFO_ALLOC_PRIMARY_CHUNK_SIZE), - lifoBlocksToFreeAfterMinorGC( + lifoBlocksToFreeAfterFullMinorGC( + (size_t)JSContext::TEMP_LIFO_ALLOC_PRIMARY_CHUNK_SIZE), + lifoBlocksToFreeAfterNextMinorGC( (size_t)JSContext::TEMP_LIFO_ALLOC_PRIMARY_CHUNK_SIZE), sweepGroupIndex(0), sweepGroups(nullptr), @@ -658,7 +660,7 @@ void GCRuntime::setZeal(uint8_t zeal, uint32_t frequency) { if (zeal == 0) { if (hasZealMode(ZealMode::GenerationalGC)) { - evictNursery(JS::GCReason::DEBUG_GC); + evictNursery(); nursery().leaveZealMode(); } @@ -669,7 +671,7 @@ void GCRuntime::setZeal(uint8_t zeal, uint32_t frequency) { ZealMode zealMode = ZealMode(zeal); if (zealMode == ZealMode::GenerationalGC) { - evictNursery(JS::GCReason::DEBUG_GC); + evictNursery(JS::GCReason::EVICT_NURSERY); nursery().enterZealMode(); } @@ -704,7 +706,7 @@ void GCRuntime::unsetZeal(uint8_t zeal) { } if (zealMode == ZealMode::GenerationalGC) { - evictNursery(JS::GCReason::DEBUG_GC); + evictNursery(); nursery().leaveZealMode(); } @@ -1073,6 +1075,11 @@ bool GCRuntime::setParameter(JSGCParamKey key, uint32_t value, marker->incrementalWeakMapMarkingEnabled = value != 0; } break; + case JSGC_SEMISPACE_NURSERY_ENABLED: { + AutoUnlockGC unlock(lock); + nursery().setSemispaceEnabled(value); + break; + } case JSGC_MIN_EMPTY_CHUNK_COUNT: setMinEmptyChunkCount(value, lock); break; @@ -1160,6 +1167,11 @@ void GCRuntime::resetParameter(JSGCParamKey key, AutoLockGC& lock) { TuningDefaults::IncrementalWeakMapMarkingEnabled; } break; + case JSGC_SEMISPACE_NURSERY_ENABLED: { + AutoUnlockGC unlock(lock); + nursery().setSemispaceEnabled(TuningDefaults::SemispaceNurseryEnabled); + break; + } case JSGC_MIN_EMPTY_CHUNK_COUNT: setMinEmptyChunkCount(TuningDefaults::MinEmptyChunkCount, lock); break; @@ -1241,6 +1253,8 @@ uint32_t GCRuntime::getParameter(JSGCParamKey key, const AutoLockGC& lock) { return parallelMarkingEnabled; case JSGC_INCREMENTAL_WEAKMAP_ENABLED: return marker().incrementalWeakMapMarkingEnabled; + case JSGC_SEMISPACE_NURSERY_ENABLED: + return nursery().semispaceEnabled(); case JSGC_CHUNK_BYTES: return ChunkSize; case JSGC_HELPER_THREAD_RATIO: @@ -2135,7 +2149,7 @@ void GCRuntime::queueUnusedLifoBlocksForFree(LifoAlloc* lifo) { } void GCRuntime::queueAllLifoBlocksForFreeAfterMinorGC(LifoAlloc* lifo) { - lifoBlocksToFreeAfterMinorGC.ref().transferFrom(lifo); + lifoBlocksToFreeAfterFullMinorGC.ref().transferFrom(lifo); } void GCRuntime::queueBuffersForFreeAfterMinorGC(Nursery::BufferSet& buffers) { @@ -2741,24 +2755,7 @@ void GCRuntime::endPreparePhase(JS::GCReason reason) { MOZ_ASSERT(unmarkTask.isIdle()); for (GCZonesIter zone(this); !zone.done(); zone.next()) { - /* - * In an incremental GC, clear the area free lists to ensure that subsequent - * allocations refill them and end up marking new cells back. See - * arenaAllocatedDuringGC(). - */ - zone->arenas.clearFreeLists(); - zone->setPreservingCode(false); - -#ifdef JS_GC_ZEAL - if (hasZealMode(ZealMode::YieldBeforeRootMarking)) { - for (auto kind : AllAllocKinds()) { - for (ArenaIterInGC arena(zone, kind); !arena.done(); arena.next()) { - arena->checkNoMarkedCells(); - } - } - } -#endif } // Discard JIT code more aggressively if the process is approaching its @@ -2800,7 +2797,7 @@ void GCRuntime::endPreparePhase(JS::GCReason reason) { */ { - gcstats::AutoPhase ap1(stats(), gcstats::PhaseKind::PREPARE); + gcstats::AutoPhase ap(stats(), gcstats::PhaseKind::PREPARE); AutoLockHelperThreadState helperLock; @@ -2817,20 +2814,6 @@ void GCRuntime::endPreparePhase(JS::GCReason reason) { haveDiscardedJITCodeThisSlice = true; /* - * Relazify functions after discarding JIT code (we can't relazify - * functions with JIT code) and before the actual mark phase, so that - * the current GC can collect the JSScripts we're unlinking here. We do - * this only when we're performing a shrinking GC, as too much - * relazification can cause performance issues when we have to reparse - * the same functions over and over. - */ - if (isShrinkingGC()) { - relazifyFunctionsForShrinkingGC(); - purgePropMapTablesForShrinkingGC(); - purgeSourceURLsForShrinkingGC(); - } - - /* * We must purge the runtime at the beginning of an incremental GC. The * danger if we purge later is that the snapshot invariant of * incremental GC will be broken, as follows. If some object is @@ -2840,8 +2823,25 @@ void GCRuntime::endPreparePhase(JS::GCReason reason) { * it. This object might never be marked, so a GC hazard would exist. */ purgeRuntime(); + } + + // This will start background free for lifo blocks queued by purgeRuntime, + // even if there's nothing in the nursery. + collectNurseryFromMajorGC(reason); - startBackgroundFreeAfterMinorGC(); + { + gcstats::AutoPhase ap(stats(), gcstats::PhaseKind::PREPARE); + // Relazify functions after discarding JIT code (we can't relazify functions + // with JIT code) and before the actual mark phase, so that the current GC + // can collect the JSScripts we're unlinking here. We do this only when + // we're performing a shrinking GC, as too much relazification can cause + // performance issues when we have to reparse the same functions over and + // over. + if (isShrinkingGC()) { + relazifyFunctionsForShrinkingGC(); + purgePropMapTablesForShrinkingGC(); + purgeSourceURLsForShrinkingGC(); + } if (isShutdownGC()) { /* Clear any engine roots that may hold external data live. */ @@ -2903,6 +2903,21 @@ void GCRuntime::beginMarkPhase(AutoGCSession& session) { #endif for (GCZonesIter zone(this); !zone.done(); zone.next()) { + // In an incremental GC, clear the arena free lists to ensure that + // subsequent allocations refill them and end up marking new cells black. + // See arenaAllocatedDuringGC(). + zone->arenas.clearFreeLists(); + +#ifdef JS_GC_ZEAL + if (hasZealMode(ZealMode::YieldBeforeRootMarking)) { + for (auto kind : AllAllocKinds()) { + for (ArenaIter arena(zone, kind); !arena.done(); arena.next()) { + arena->checkNoMarkedCells(); + } + } + } +#endif + // Incremental marking barriers are enabled at this point. zone->changeGCState(Zone::Prepare, zone->initialMarkingState()); @@ -3715,11 +3730,8 @@ void GCRuntime::incrementalSlice(SliceBudget& budget, JS::GCReason reason, [[fallthrough]]; case State::MarkRoots: - if (NeedToCollectNursery(this)) { - collectNurseryFromMajorGC(reason); - } - endPreparePhase(reason); + beginMarkPhase(session); incrementalState = State::Mark; @@ -3878,8 +3890,11 @@ void GCRuntime::incrementalSlice(SliceBudget& budget, JS::GCReason reason, } void GCRuntime::collectNurseryFromMajorGC(JS::GCReason reason) { - collectNursery(gcOptions(), reason, + collectNursery(gcOptions(), JS::GCReason::EVICT_NURSERY, gcstats::PhaseKind::EVICT_NURSERY_FOR_MAJOR_GC); + + MOZ_ASSERT(nursery().isEmpty()); + MOZ_ASSERT(storeBuffer().isEmpty()); } bool GCRuntime::hasForegroundWork() const { @@ -4733,26 +4748,43 @@ void GCRuntime::collectNursery(JS::GCOptions options, JS::GCReason reason, gcstats::AutoPhase ap(stats(), phase); nursery().collect(options, reason); - MOZ_ASSERT(nursery().isEmpty()); startBackgroundFreeAfterMinorGC(); + + // We ignore gcMaxBytes when allocating for minor collection. However, if we + // overflowed, we disable the nursery. The next time we allocate, we'll fail + // because bytes >= gcMaxBytes. + if (heapSize.bytes() >= tunables.gcMaxBytes()) { + if (!nursery().isEmpty()) { + nursery().collect(options, JS::GCReason::DISABLE_GENERATIONAL_GC); + MOZ_ASSERT(nursery().isEmpty()); + startBackgroundFreeAfterMinorGC(); + } + nursery().disable(); + } } void GCRuntime::startBackgroundFreeAfterMinorGC() { - MOZ_ASSERT(nursery().isEmpty()); + // Called after nursery collection. Free whatever blocks are safe to free now. - { - AutoLockHelperThreadState lock; + AutoLockHelperThreadState lock; - lifoBlocksToFree.ref().transferFrom(&lifoBlocksToFreeAfterMinorGC.ref()); + lifoBlocksToFree.ref().transferFrom(&lifoBlocksToFreeAfterNextMinorGC.ref()); - if (lifoBlocksToFree.ref().isEmpty() && - buffersToFreeAfterMinorGC.ref().empty()) { - return; - } + if (nursery().tenuredEverything) { + lifoBlocksToFree.ref().transferFrom( + &lifoBlocksToFreeAfterFullMinorGC.ref()); + } else { + lifoBlocksToFreeAfterNextMinorGC.ref().transferFrom( + &lifoBlocksToFreeAfterFullMinorGC.ref()); + } + + if (lifoBlocksToFree.ref().isEmpty() && + buffersToFreeAfterMinorGC.ref().empty()) { + return; } - startBackgroundFree(); + freeTask.startOrRunIfIdle(lock); } bool GCRuntime::gcIfRequestedImpl(bool eagerOk) { diff --git a/js/src/gc/GC.h b/js/src/gc/GC.h index 4e4634d804..7f603b066f 100644 --- a/js/src/gc/GC.h +++ b/js/src/gc/GC.h @@ -83,7 +83,8 @@ class TenuredChunk; _("maxHelperThreads", JSGC_MAX_HELPER_THREADS, true) \ _("helperThreadCount", JSGC_HELPER_THREAD_COUNT, false) \ _("markingThreadCount", JSGC_MARKING_THREAD_COUNT, true) \ - _("systemPageSizeKB", JSGC_SYSTEM_PAGE_SIZE_KB, false) + _("systemPageSizeKB", JSGC_SYSTEM_PAGE_SIZE_KB, false) \ + _("semispaceNurseryEnabled", JSGC_SEMISPACE_NURSERY_ENABLED, true) // Get the key and writability give a GC parameter name. extern bool GetGCParameterInfo(const char* name, JSGCParamKey* keyOut, diff --git a/js/src/gc/GCAPI.cpp b/js/src/gc/GCAPI.cpp index 293bfce80d..d2eab44dea 100644 --- a/js/src/gc/GCAPI.cpp +++ b/js/src/gc/GCAPI.cpp @@ -487,8 +487,7 @@ JS_PUBLIC_API bool JS::WasIncrementalGC(JSRuntime* rt) { bool js::gc::CreateUniqueIdForNativeObject(NativeObject* nobj, uint64_t* uidp) { JSRuntime* runtime = nobj->runtimeFromMainThread(); *uidp = NextCellUniqueId(runtime); - JSContext* cx = runtime->mainContextFromOwnThread(); - return nobj->setUniqueId(cx, *uidp); + return nobj->setUniqueId(runtime, *uidp); } bool js::gc::CreateUniqueIdForNonNativeObject(Cell* cell, @@ -793,6 +792,15 @@ const char* CellColorName(CellColor color) { } /* namespace gc */ } /* namespace js */ +JS_PUBLIC_API bool js::gc::IsDeadNurseryObject(JSObject* obj) { + MOZ_ASSERT(JS::RuntimeHeapIsMinorCollecting()); + MOZ_ASSERT(obj); + MOZ_ASSERT(IsInsideNursery(obj)); + MOZ_ASSERT(!IsForwarded(obj)); + + return obj->runtimeFromMainThread()->gc.nursery().inCollectedRegion(obj); +} + JS_PUBLIC_API void js::gc::FinalizeDeadNurseryObject(JSContext* cx, JSObject* obj) { CHECK_THREAD(cx); diff --git a/js/src/gc/GCInternals.h b/js/src/gc/GCInternals.h index c234ad4b2b..9a3edc2c9d 100644 --- a/js/src/gc/GCInternals.h +++ b/js/src/gc/GCInternals.h @@ -329,7 +329,7 @@ inline bool IsOOMReason(JS::GCReason reason) { reason == JS::GCReason::MEM_PRESSURE; } -void* AllocateCellInGC(JS::Zone* zone, AllocKind thingKind); +void* AllocateTenuredCellInGC(JS::Zone* zone, AllocKind thingKind); void ReadProfileEnv(const char* envName, const char* helpText, bool* enableOut, bool* workersOut, mozilla::TimeDuration* thresholdOut); diff --git a/js/src/gc/GCRuntime.h b/js/src/gc/GCRuntime.h index c9f660b4d7..851e477359 100644 --- a/js/src/gc/GCRuntime.h +++ b/js/src/gc/GCRuntime.h @@ -1205,7 +1205,8 @@ class GCRuntime { * a background thread. */ HelperThreadLockData<LifoAlloc> lifoBlocksToFree; - MainThreadData<LifoAlloc> lifoBlocksToFreeAfterMinorGC; + MainThreadData<LifoAlloc> lifoBlocksToFreeAfterFullMinorGC; + MainThreadData<LifoAlloc> lifoBlocksToFreeAfterNextMinorGC; HelperThreadLockData<Nursery::BufferSet> buffersToFreeAfterMinorGC; /* Index of current sweep group (for stats). */ diff --git a/js/src/gc/Heap-inl.h b/js/src/gc/Heap-inl.h index 95bd841cae..30937a7236 100644 --- a/js/src/gc/Heap-inl.h +++ b/js/src/gc/Heap-inl.h @@ -44,6 +44,10 @@ inline void js::gc::Arena::init(JS::Zone* zoneArg, AllocKind kind, } setAsFullyUnused(); + +#ifdef DEBUG + checkNoMarkedCells(); +#endif } inline void js::gc::Arena::release(const AutoLockGC& lock) { diff --git a/js/src/gc/MallocedBlockCache.h b/js/src/gc/MallocedBlockCache.h index cd7d1e1064..6fc577044e 100644 --- a/js/src/gc/MallocedBlockCache.h +++ b/js/src/gc/MallocedBlockCache.h @@ -70,6 +70,8 @@ class MallocedBlockCache { ~MallocedBlockCache(); + static inline size_t listIDForSize(size_t size); + // Allocation and freeing. Use `alloc` to allocate. `allocSlow` is // `alloc`s fallback path. Do not call it directly, since it doesn't handle // all cases by itself. @@ -89,7 +91,8 @@ class MallocedBlockCache { size_t sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const; }; -inline PointerAndUint7 MallocedBlockCache::alloc(size_t size) { +/* static */ +inline size_t MallocedBlockCache::listIDForSize(size_t size) { // Figure out which free list can give us a block of size `size`, after it // has been rounded up to a multiple of `step`. // @@ -122,11 +125,23 @@ inline PointerAndUint7 MallocedBlockCache::alloc(size_t size) { size_t i = size / STEP; MOZ_ASSERT(i > 0); + if (i >= NUM_LISTS) { + return OVERSIZE_BLOCK_LIST_ID; + } + + return i; +} + +inline PointerAndUint7 MallocedBlockCache::alloc(size_t size) { + size_t i = listIDForSize(size); + MOZ_ASSERT(i < NUM_LISTS); + // Fast path: try to pull a block from the relevant list. - if (MOZ_LIKELY(i < NUM_LISTS && // "block is small enough to cache" - !lists[i].empty())) { // "a cached block is available" + if (MOZ_LIKELY( + i != OVERSIZE_BLOCK_LIST_ID && // "block is small enough to cache" + !lists[i].empty())) { // "a cached block is available" // Check that i is the right list - MOZ_ASSERT(i * STEP == size); + MOZ_ASSERT(i * STEP == js::RoundUp(size, STEP)); void* block = lists[i].popCopy(); return PointerAndUint7(block, i); } diff --git a/js/src/gc/Nursery-inl.h b/js/src/gc/Nursery-inl.h index 3a29d76c07..3be063697a 100644 --- a/js/src/gc/Nursery-inl.h +++ b/js/src/gc/Nursery-inl.h @@ -16,6 +16,12 @@ #include "vm/JSContext.h" #include "vm/NativeObject.h" +namespace js { +namespace gc { +struct Cell; +} // namespace gc +} // namespace js + inline JSRuntime* js::Nursery::runtime() const { return gc->rt; } template <typename T> @@ -23,6 +29,50 @@ bool js::Nursery::isInside(const SharedMem<T>& p) const { return isInside(p.unwrap(/*safe - used for value in comparison above*/)); } +inline bool js::Nursery::shouldTenure(gc::Cell* cell) { + MOZ_ASSERT(semispaceEnabled()); + MOZ_ASSERT(inCollectedRegion(cell)); + + size_t offset = fromSpace.offsetFromAddress(uintptr_t(cell)); + MOZ_ASSERT(offset >= + fromSpace.offsetFromExclusiveAddress(fromSpace.startPosition_)); + return offset <= tenureThreshold_; +} + +inline bool js::Nursery::inCollectedRegion(gc::Cell* cell) const { + gc::ChunkBase* chunk = gc::detail::GetCellChunkBase(cell); + return chunk->getKind() == gc::ChunkKind::NurseryFromSpace; +} + +inline bool js::Nursery::inCollectedRegion(void* ptr) const { + if (!semispaceEnabled()) { + return toSpace.isInside(ptr); + } + + return fromSpace.isInside(ptr); +} + +inline size_t js::Nursery::Space::offsetFromExclusiveAddress( + uintptr_t addr) const { + if ((addr & gc::ChunkMask) == 0) { + // |addr| points one past the end of the previous chunk. + return offsetFromAddress(addr - 1) + 1; + } + + return offsetFromAddress(addr); +} + +inline size_t js::Nursery::Space::offsetFromAddress(uintptr_t addr) const { + gc::ChunkBase* chunk = + gc::detail::GetCellChunkBase(reinterpret_cast<gc::Cell*>(addr)); + MOZ_ASSERT(chunk->getKind() == kind); + MOZ_ASSERT(findChunkIndex(addr & ~gc::ChunkMask) == chunk->nurseryChunkIndex); + + uint32_t offset = addr & gc::ChunkMask; + MOZ_ASSERT(offset >= sizeof(gc::ChunkBase)); + return (chunk->nurseryChunkIndex << gc::ChunkShift) | offset; +} + MOZ_ALWAYS_INLINE /* static */ bool js::Nursery::getForwardedPointer( js::gc::Cell** ref) { js::gc::Cell* cell = (*ref); @@ -80,7 +130,7 @@ inline void js::Nursery::setForwardingPointer(void* oldData, void* newData, inline void js::Nursery::setDirectForwardingPointer(void* oldData, void* newData) { MOZ_ASSERT(isInside(oldData)); - MOZ_ASSERT(!isInside(newData)); + MOZ_ASSERT_IF(isInside(newData), !inCollectedRegion(newData)); new (oldData) BufferRelocationOverlay{newData}; } @@ -123,8 +173,8 @@ inline void* js::Nursery::tryAllocateCell(gc::AllocSite* site, size_t size, inline void* js::Nursery::tryAllocate(size_t size) { MOZ_ASSERT(isEnabled()); - MOZ_ASSERT(!JS::RuntimeHeapIsBusy()); - MOZ_ASSERT_IF(currentChunk_ == startChunk_, position() >= startPosition_); + MOZ_ASSERT_IF(JS::RuntimeHeapIsBusy(), JS::RuntimeHeapIsMinorCollecting()); + MOZ_ASSERT_IF(currentChunk() == startChunk(), position() >= startPosition()); MOZ_ASSERT(size % gc::CellAlignBytes == 0); MOZ_ASSERT(position() % gc::CellAlignBytes == 0); @@ -138,7 +188,7 @@ inline void* js::Nursery::tryAllocate(size_t size) { "Successful allocation cannot result in nullptr"); } - position_ = position() + size; + toSpace.position_ = position() + size; DebugOnlyPoison(ptr, JS_ALLOCATED_NURSERY_PATTERN, size, MemCheckKind::MakeUndefined); @@ -148,30 +198,33 @@ inline void* js::Nursery::tryAllocate(size_t size) { inline bool js::Nursery::registerTrailer(PointerAndUint7 blockAndListID, size_t nBytes) { - MOZ_ASSERT(trailersAdded_.length() == trailersRemoved_.length()); + MOZ_ASSERT(toSpace.trailersAdded_.length() == + toSpace.trailersRemoved_.length()); MOZ_ASSERT(nBytes > 0); - if (MOZ_UNLIKELY(!trailersAdded_.append(blockAndListID))) { + if (MOZ_UNLIKELY(!toSpace.trailersAdded_.append(blockAndListID))) { return false; } - if (MOZ_UNLIKELY(!trailersRemoved_.append(nullptr))) { - trailersAdded_.popBack(); + if (MOZ_UNLIKELY(!toSpace.trailersRemoved_.append(nullptr))) { + toSpace.trailersAdded_.popBack(); return false; } // This is a clone of the logic in ::registerMallocedBuffer. It may be // that some other heuristic is better, once we know more about the // typical behaviour of wasm-GC applications. - trailerBytes_ += nBytes; - if (MOZ_UNLIKELY(trailerBytes_ > capacity() * 8)) { + toSpace.trailerBytes_ += nBytes; + if (MOZ_UNLIKELY(toSpace.trailerBytes_ > capacity() * 8)) { requestMinorGC(JS::GCReason::NURSERY_TRAILERS); } return true; } inline void js::Nursery::unregisterTrailer(void* block) { - MOZ_ASSERT(trailersRemovedUsed_ < trailersRemoved_.length()); - trailersRemoved_[trailersRemovedUsed_] = block; - trailersRemovedUsed_++; + // Unlike removeMallocedBuffer this is only called during minor GC. + MOZ_ASSERT(fromSpace.trailersRemovedUsed_ < + fromSpace.trailersRemoved_.length()); + fromSpace.trailersRemoved_[fromSpace.trailersRemovedUsed_] = block; + fromSpace.trailersRemovedUsed_++; } namespace js { @@ -181,13 +234,20 @@ namespace js { // instead. template <typename T> -static inline T* AllocateCellBuffer(JSContext* cx, gc::Cell* cell, +static inline T* AllocateCellBuffer(Nursery& nursery, gc::Cell* cell, uint32_t count) { size_t nbytes = RoundUp(count * sizeof(T), sizeof(Value)); - auto* buffer = static_cast<T*>(cx->nursery().allocateBuffer( - cell->zone(), cell, nbytes, js::MallocArena)); + return static_cast<T*>( + nursery.allocateBuffer(cell->zone(), cell, nbytes, js::MallocArena)); +} + +template <typename T> +static inline T* AllocateCellBuffer(JSContext* cx, gc::Cell* cell, + uint32_t count) { + T* buffer = AllocateCellBuffer<T>(cx->nursery(), cell, count); if (!buffer) { ReportOutOfMemory(cx); + return nullptr; } return buffer; diff --git a/js/src/gc/Nursery.cpp b/js/src/gc/Nursery.cpp index 660daa8d4c..4753848c56 100644 --- a/js/src/gc/Nursery.cpp +++ b/js/src/gc/Nursery.cpp @@ -38,6 +38,7 @@ #include "gc/Heap-inl.h" #include "gc/Marking-inl.h" #include "gc/StableCellHasher-inl.h" +#include "gc/StoreBuffer-inl.h" #include "vm/GeckoProfiler-inl.h" using namespace js; @@ -50,15 +51,22 @@ using mozilla::TimeStamp; namespace js { +static constexpr size_t NurseryChunkHeaderSize = + RoundUp(sizeof(ChunkBase), CellAlignBytes); + +// The amount of space in a nursery chunk available to allocations. +static constexpr size_t NurseryChunkUsableSize = + ChunkSize - NurseryChunkHeaderSize; + struct NurseryChunk : public ChunkBase { - char data[Nursery::NurseryChunkUsableSize]; + alignas(CellAlignBytes) uint8_t data[NurseryChunkUsableSize]; - static NurseryChunk* fromChunk(gc::TenuredChunk* chunk); + static NurseryChunk* fromChunk(TenuredChunk* chunk, ChunkKind kind, + uint8_t index); - explicit NurseryChunk(JSRuntime* runtime) - : ChunkBase(runtime, &runtime->gc.storeBuffer()) {} + explicit NurseryChunk(JSRuntime* runtime, ChunkKind kind, uint8_t chunkIndex) + : ChunkBase(runtime, &runtime->gc.storeBuffer(), kind, chunkIndex) {} - void poisonAndInit(JSRuntime* rt, size_t size = ChunkSize); void poisonRange(size_t start, size_t end, uint8_t value, MemCheckKind checkKind); void poisonAfterEvict(size_t extent = ChunkSize); @@ -75,22 +83,29 @@ struct NurseryChunk : public ChunkBase { uintptr_t start() const { return uintptr_t(&data); } uintptr_t end() const { return uintptr_t(this) + ChunkSize; } }; -static_assert(sizeof(js::NurseryChunk) == gc::ChunkSize, - "Nursery chunk size must match gc::Chunk size."); +static_assert(sizeof(NurseryChunk) == ChunkSize, + "Nursery chunk size must match Chunk size."); +static_assert(offsetof(NurseryChunk, data) == NurseryChunkHeaderSize); class NurseryDecommitTask : public GCParallelTask { public: explicit NurseryDecommitTask(gc::GCRuntime* gc); - bool reserveSpaceForBytes(size_t nbytes); + bool reserveSpaceForChunks(size_t nchunks); bool isEmpty(const AutoLockHelperThreadState& lock) const; void queueChunk(NurseryChunk* chunk, const AutoLockHelperThreadState& lock); - void queueRange(size_t newCapacity, NurseryChunk& chunk, + void queueRange(size_t newCapacity, NurseryChunk* chunk, const AutoLockHelperThreadState& lock); private: + struct Region { + NurseryChunk* chunk; + size_t startOffset; + }; + using NurseryChunkVector = Vector<NurseryChunk*, 0, SystemAllocPolicy>; + using RegionVector = Vector<Region, 2, SystemAllocPolicy>; void run(AutoLockHelperThreadState& lock) override; @@ -98,25 +113,21 @@ class NurseryDecommitTask : public GCParallelTask { const NurseryChunkVector& chunksToDecommit() const { return chunksToDecommit_.ref(); } + RegionVector& regionsToDecommit() { return regionsToDecommit_.ref(); } + const RegionVector& regionsToDecommit() const { + return regionsToDecommit_.ref(); + } MainThreadOrGCTaskData<NurseryChunkVector> chunksToDecommit_; - - MainThreadOrGCTaskData<NurseryChunk*> partialChunk; - MainThreadOrGCTaskData<size_t> partialCapacity; + MainThreadOrGCTaskData<RegionVector> regionsToDecommit_; }; } // namespace js -inline void js::NurseryChunk::poisonAndInit(JSRuntime* rt, size_t size) { - MOZ_ASSERT(size >= sizeof(ChunkBase)); - MOZ_ASSERT(size <= ChunkSize); - poisonRange(0, size, JS_FRESH_NURSERY_PATTERN, MemCheckKind::MakeUndefined); - new (this) NurseryChunk(rt); -} - inline void js::NurseryChunk::poisonRange(size_t start, size_t end, uint8_t value, MemCheckKind checkKind) { + MOZ_ASSERT(start >= NurseryChunkHeaderSize); MOZ_ASSERT((start % gc::CellAlignBytes) == 0); MOZ_ASSERT((end % gc::CellAlignBytes) == 0); MOZ_ASSERT(end >= start); @@ -132,12 +143,12 @@ inline void js::NurseryChunk::poisonRange(size_t start, size_t end, } inline void js::NurseryChunk::poisonAfterEvict(size_t extent) { - poisonRange(sizeof(ChunkBase), extent, JS_SWEPT_NURSERY_PATTERN, + poisonRange(NurseryChunkHeaderSize, extent, JS_SWEPT_NURSERY_PATTERN, MemCheckKind::MakeNoAccess); } inline void js::NurseryChunk::markPagesUnusedHard(size_t startOffset) { - MOZ_ASSERT(startOffset >= sizeof(ChunkBase)); // Don't touch the header. + MOZ_ASSERT(startOffset >= NurseryChunkHeaderSize); // Don't touch the header. MOZ_ASSERT(startOffset >= SystemPageSize()); MOZ_ASSERT(startOffset <= ChunkSize); uintptr_t start = uintptr_t(this) + startOffset; @@ -146,7 +157,7 @@ inline void js::NurseryChunk::markPagesUnusedHard(size_t startOffset) { } inline bool js::NurseryChunk::markPagesInUseHard(size_t endOffset) { - MOZ_ASSERT(endOffset >= sizeof(ChunkBase)); + MOZ_ASSERT(endOffset >= NurseryChunkHeaderSize); MOZ_ASSERT(endOffset >= SystemPageSize()); MOZ_ASSERT(endOffset <= ChunkSize); uintptr_t start = uintptr_t(this) + SystemPageSize(); @@ -155,23 +166,25 @@ inline bool js::NurseryChunk::markPagesInUseHard(size_t endOffset) { } // static -inline js::NurseryChunk* js::NurseryChunk::fromChunk(TenuredChunk* chunk) { - return reinterpret_cast<NurseryChunk*>(chunk); +inline js::NurseryChunk* js::NurseryChunk::fromChunk(TenuredChunk* chunk, + ChunkKind kind, + uint8_t index) { + return new (chunk) NurseryChunk(chunk->runtime, kind, index); } js::NurseryDecommitTask::NurseryDecommitTask(gc::GCRuntime* gc) : GCParallelTask(gc, gcstats::PhaseKind::NONE) { // This can occur outside GCs so doesn't have a stats phase. + MOZ_ALWAYS_TRUE(regionsToDecommit().reserve(2)); } bool js::NurseryDecommitTask::isEmpty( const AutoLockHelperThreadState& lock) const { - return chunksToDecommit().empty() && !partialChunk; + return chunksToDecommit().empty() && regionsToDecommit().empty(); } -bool js::NurseryDecommitTask::reserveSpaceForBytes(size_t nbytes) { +bool js::NurseryDecommitTask::reserveSpaceForChunks(size_t nchunks) { MOZ_ASSERT(isIdle()); - size_t nchunks = HowMany(nbytes, ChunkSize); return chunksToDecommit().reserve(nchunks); } @@ -182,15 +195,14 @@ void js::NurseryDecommitTask::queueChunk( } void js::NurseryDecommitTask::queueRange( - size_t newCapacity, NurseryChunk& newChunk, + size_t newCapacity, NurseryChunk* chunk, const AutoLockHelperThreadState& lock) { MOZ_ASSERT(isIdle(lock)); - MOZ_ASSERT(!partialChunk); + MOZ_ASSERT(regionsToDecommit_.ref().length() < 2); MOZ_ASSERT(newCapacity < ChunkSize); MOZ_ASSERT(newCapacity % SystemPageSize() == 0); - partialChunk = &newChunk; - partialCapacity = newCapacity; + regionsToDecommit().infallibleAppend(Region{chunk, newCapacity}); } void js::NurseryDecommitTask::run(AutoLockHelperThreadState& lock) { @@ -204,25 +216,20 @@ void js::NurseryDecommitTask::run(AutoLockHelperThreadState& lock) { gc->recycleChunk(tenuredChunk, lock); } - if (partialChunk) { - { - AutoUnlockHelperThreadState unlock(lock); - partialChunk->markPagesUnusedHard(partialCapacity); - } - partialChunk = nullptr; - partialCapacity = 0; + while (!regionsToDecommit().empty()) { + Region region = regionsToDecommit().popCopy(); + AutoUnlockHelperThreadState unlock(lock); + region.chunk->markPagesUnusedHard(region.startOffset); } } js::Nursery::Nursery(GCRuntime* gc) - : position_(0), - currentEnd_(0), + : toSpace(ChunkKind::NurseryToSpace), + fromSpace(ChunkKind::NurseryFromSpace), gc(gc), - currentChunk_(0), - startChunk_(0), - startPosition_(0), capacity_(0), enableProfiling_(false), + semispaceEnabled_(gc::TuningDefaults::SemispaceNurseryEnabled), canAllocateStrings_(true), canAllocateBigInts_(true), reportDeduplications_(false), @@ -232,6 +239,11 @@ js::Nursery::Nursery(GCRuntime* gc) prevPosition_(0), hasRecentGrowthData(false), smoothedTargetSize(0.0) { + // Try to keep fields used by allocation fast path together at the start of + // the nursery. + static_assert(offsetof(Nursery, toSpace.position_) < TypicalCacheLineSize); + static_assert(offsetof(Nursery, toSpace.currentEnd_) < TypicalCacheLineSize); + const char* env = getenv("MOZ_NURSERY_STRINGS"); if (env && *env) { canAllocateStrings_ = (*env == '1'); @@ -316,12 +328,13 @@ bool js::Nursery::init(AutoLockGCBgAlloc& lock) { js::Nursery::~Nursery() { disable(); } void js::Nursery::enable() { - MOZ_ASSERT(isEmpty()); - MOZ_ASSERT(!gc->isVerifyPreBarriersEnabled()); if (isEnabled()) { return; } + MOZ_ASSERT(isEmpty()); + MOZ_ASSERT(!gc->isVerifyPreBarriersEnabled()); + { AutoLockGCBgAlloc lock(gc); if (!initFirstChunk(lock)) { @@ -344,25 +357,60 @@ void js::Nursery::enable() { bool js::Nursery::initFirstChunk(AutoLockGCBgAlloc& lock) { MOZ_ASSERT(!isEnabled()); + MOZ_ASSERT(toSpace.chunks_.length() == 0); + MOZ_ASSERT(fromSpace.chunks_.length() == 0); - capacity_ = tunables().gcMinNurseryBytes(); + setCapacity(minSpaceSize()); - if (!decommitTask->reserveSpaceForBytes(capacity_) || - !allocateNextChunk(0, lock)) { - capacity_ = 0; + size_t nchunks = toSpace.maxChunkCount_ + fromSpace.maxChunkCount_; + if (!decommitTask->reserveSpaceForChunks(nchunks) || + !allocateNextChunk(lock)) { + setCapacity(0); + MOZ_ASSERT(toSpace.isEmpty()); + MOZ_ASSERT(fromSpace.isEmpty()); return false; } - moveToStartOfChunk(0); - setStartToCurrentPosition(); + toSpace.moveToStartOfChunk(this, 0); + toSpace.setStartToCurrentPosition(); + + if (semispaceEnabled_) { + fromSpace.moveToStartOfChunk(this, 0); + fromSpace.setStartToCurrentPosition(); + } + + MOZ_ASSERT(toSpace.isEmpty()); + MOZ_ASSERT(fromSpace.isEmpty()); + poisonAndInitCurrentChunk(); // Clear any information about previous collections. clearRecentGrowthData(); + tenureThreshold_ = 0; + +#ifdef DEBUG + toSpace.checkKind(ChunkKind::NurseryToSpace); + fromSpace.checkKind(ChunkKind::NurseryFromSpace); +#endif + return true; } +size_t RequiredChunkCount(size_t nbytes) { + return nbytes <= ChunkSize ? 1 : nbytes / ChunkSize; +} + +void js::Nursery::setCapacity(size_t newCapacity) { + MOZ_ASSERT(newCapacity == roundSize(newCapacity)); + capacity_ = newCapacity; + size_t count = RequiredChunkCount(newCapacity); + toSpace.maxChunkCount_ = count; + if (semispaceEnabled_) { + fromSpace.maxChunkCount_ = count; + } +} + void js::Nursery::disable() { MOZ_ASSERT(isEmpty()); if (!isEnabled()) { @@ -371,15 +419,19 @@ void js::Nursery::disable() { // Free all chunks. decommitTask->join(); - freeChunksFrom(0); + freeChunksFrom(toSpace, 0); + freeChunksFrom(fromSpace, 0); decommitTask->runFromMainThread(); - capacity_ = 0; + setCapacity(0); // We must reset currentEnd_ so that there is no space for anything in the // nursery. JIT'd code uses this even if the nursery is disabled. - currentEnd_ = 0; - position_ = 0; + toSpace = Space(ChunkKind::NurseryToSpace); + fromSpace = Space(ChunkKind::NurseryFromSpace); + MOZ_ASSERT(toSpace.isEmpty()); + MOZ_ASSERT(fromSpace.isEmpty()); + gc->storeBuffer().disable(); if (gc->wasInitialized()) { @@ -464,16 +516,59 @@ void js::Nursery::discardCodeAndSetJitFlagsForZone(JS::Zone* zone) { } } +void js::Nursery::setSemispaceEnabled(bool enabled) { + if (semispaceEnabled() == enabled) { + return; + } + + bool wasEnabled = isEnabled(); + if (wasEnabled) { + if (!isEmpty()) { + gc->minorGC(JS::GCReason::EVICT_NURSERY); + } + disable(); + } + + semispaceEnabled_ = enabled; + + if (wasEnabled) { + enable(); + } +} + bool js::Nursery::isEmpty() const { + MOZ_ASSERT(fromSpace.isEmpty()); + if (!isEnabled()) { return true; } if (!gc->hasZealMode(ZealMode::GenerationalGC)) { - MOZ_ASSERT(startChunk_ == 0); - MOZ_ASSERT(startPosition_ == chunk(0).start()); + MOZ_ASSERT(startChunk() == 0); + MOZ_ASSERT(startPosition() == chunk(0).start()); } - return position() == startPosition_; + + return toSpace.isEmpty(); +} + +bool js::Nursery::Space::isEmpty() const { return position_ == startPosition_; } + +static size_t AdjustSizeForSemispace(size_t size, bool semispaceEnabled) { + if (!semispaceEnabled) { + return size; + } + + return Nursery::roundSize(size / 2); +} + +size_t js::Nursery::maxSpaceSize() const { + return AdjustSizeForSemispace(tunables().gcMaxNurseryBytes(), + semispaceEnabled_); +} + +size_t js::Nursery::minSpaceSize() const { + return AdjustSizeForSemispace(tunables().gcMinNurseryBytes(), + semispaceEnabled_); } #ifdef JS_GC_ZEAL @@ -501,9 +596,10 @@ void js::Nursery::enterZealMode() { MemCheckKind::MakeUndefined); } - capacity_ = RoundUp(tunables().gcMaxNurseryBytes(), ChunkSize); + setCapacity(maxSpaceSize()); - if (!decommitTask->reserveSpaceForBytes(capacity_)) { + size_t nchunks = toSpace.maxChunkCount_ + fromSpace.maxChunkCount_; + if (!decommitTask->reserveSpaceForChunks(nchunks)) { oomUnsafe.crash("Nursery::enterZealMode"); } @@ -517,8 +613,14 @@ void js::Nursery::leaveZealMode() { MOZ_ASSERT(isEmpty()); - moveToStartOfChunk(0); - setStartToCurrentPosition(); + toSpace.moveToStartOfChunk(this, 0); + toSpace.setStartToCurrentPosition(); + + if (semispaceEnabled_) { + fromSpace.moveToStartOfChunk(this, 0); + fromSpace.setStartToCurrentPosition(); + } + poisonAndInitCurrentChunk(); } #endif // JS_GC_ZEAL @@ -573,7 +675,7 @@ MOZ_NEVER_INLINE JS::GCReason Nursery::handleAllocationFailure() { } bool Nursery::moveToNextChunk() { - unsigned chunkno = currentChunk_ + 1; + unsigned chunkno = currentChunk() + 1; MOZ_ASSERT(chunkno <= maxChunkCount()); MOZ_ASSERT(chunkno <= allocatedChunkCount()); if (chunkno == maxChunkCount()) { @@ -584,7 +686,7 @@ bool Nursery::moveToNextChunk() { TimeStamp start = TimeStamp::Now(); { AutoLockGCBgAlloc lock(gc); - if (!allocateNextChunk(chunkno, lock)) { + if (!allocateNextChunk(lock)) { return false; } } @@ -688,16 +790,16 @@ void* js::Nursery::reallocateBuffer(Zone* zone, Cell* cell, void* oldBuffer, } if (!isInside(oldBuffer)) { - MOZ_ASSERT(mallocedBufferBytes >= oldBytes); + MOZ_ASSERT(toSpace.mallocedBufferBytes >= oldBytes); void* newBuffer = zone->pod_realloc<uint8_t>((uint8_t*)oldBuffer, oldBytes, newBytes); if (newBuffer) { if (oldBuffer != newBuffer) { MOZ_ALWAYS_TRUE( - mallocedBuffers.rekeyAs(oldBuffer, newBuffer, newBuffer)); + toSpace.mallocedBuffers.rekeyAs(oldBuffer, newBuffer, newBuffer)); } - mallocedBufferBytes -= oldBytes; - mallocedBufferBytes += newBytes; + toSpace.mallocedBufferBytes -= oldBytes; + toSpace.mallocedBufferBytes += newBytes; } return newBuffer; } @@ -723,27 +825,21 @@ void js::Nursery::freeBuffer(void* buffer, size_t nbytes) { #ifdef DEBUG /* static */ -inline bool Nursery::checkForwardingPointerLocation(void* ptr, - bool expectedInside) { - if (isInside(ptr) == expectedInside) { - return true; - } - +inline bool Nursery::checkForwardingPointerInsideNursery(void* ptr) { // If a zero-capacity elements header lands right at the end of a chunk then // elements data will appear to be in the next chunk. If we have a pointer to // the very start of a chunk, check the previous chunk. - if ((uintptr_t(ptr) & ChunkMask) == 0 && - isInside(reinterpret_cast<uint8_t*>(ptr) - 1) == expectedInside) { - return true; + if ((uintptr_t(ptr) & ChunkMask) == 0) { + return isInside(reinterpret_cast<uint8_t*>(ptr) - 1); } - return false; + return isInside(ptr); } #endif void Nursery::setIndirectForwardingPointer(void* oldData, void* newData) { - MOZ_ASSERT(checkForwardingPointerLocation(oldData, true)); - MOZ_ASSERT(checkForwardingPointerLocation(newData, false)); + MOZ_ASSERT(checkForwardingPointerInsideNursery(oldData)); + // |newData| may be either in the nursery or in the malloc heap. AutoEnterOOMUnsafeRegion oomUnsafe; #ifdef DEBUG @@ -791,7 +887,7 @@ void js::Nursery::forwardBufferPointer(uintptr_t* pSlotsElems) { MOZ_ASSERT(IsWriteableAddress(buffer)); } - MOZ_ASSERT(!isInside(buffer)); + MOZ_ASSERT_IF(isInside(buffer), !inCollectedRegion(buffer)); *pSlotsElems = reinterpret_cast<uintptr_t>(buffer); } @@ -1063,7 +1159,7 @@ bool js::Nursery::wantEagerCollection() const { return false; } - if (isEmpty() && capacity() == tunables().gcMinNurseryBytes()) { + if (isEmpty() && capacity() == minSpaceSize()) { return false; } @@ -1108,7 +1204,7 @@ inline bool js::Nursery::isUnderused() const { return false; } - if (capacity() == tunables().gcMinNurseryBytes()) { + if (capacity() == minSpaceSize()) { return false; } @@ -1126,8 +1222,8 @@ void js::Nursery::collect(JS::GCOptions options, JS::GCReason reason) { MOZ_ASSERT(!rt->mainContextFromOwnThread()->suppressGC); if (minorGCRequested()) { - MOZ_ASSERT(position_ == chunk(currentChunk_).end()); - position_ = prevPosition_; + MOZ_ASSERT(position() == chunk(currentChunk()).end()); + toSpace.position_ = prevPosition_; prevPosition_ = 0; minorGCTriggerReason_ = JS::GCReason::NO_REASON; rt->mainContextFromOwnThread()->clearPendingInterrupt( @@ -1141,7 +1237,7 @@ void js::Nursery::collect(JS::GCOptions options, JS::GCReason reason) { // freed after this point. gc->storeBuffer().clear(); - MOZ_ASSERT(!pretenuringNursery.hasAllocatedSites()); + MOZ_ASSERT_IF(!semispaceEnabled_, !pretenuringNursery.hasAllocatedSites()); } if (!isEnabled()) { @@ -1162,10 +1258,11 @@ void js::Nursery::collect(JS::GCOptions options, JS::GCReason reason) { previousGC.reason = JS::GCReason::NO_REASON; previousGC.nurseryUsedBytes = usedSpace(); previousGC.nurseryCapacity = capacity(); - previousGC.nurseryCommitted = committed(); - previousGC.nurseryUsedChunkCount = currentChunk_ + 1; + previousGC.nurseryCommitted = totalCommitted(); + previousGC.nurseryUsedChunkCount = currentChunk() + 1; previousGC.tenuredBytes = 0; previousGC.tenuredCells = 0; + tenuredEverything = true; // If it isn't empty, it will call doCollection, and possibly after that // isEmpty() will become true, so use another variable to keep track of the @@ -1177,29 +1274,19 @@ void js::Nursery::collect(JS::GCOptions options, JS::GCReason reason) { // space does not represent data that can be tenured MOZ_ASSERT(result.tenuredBytes <= (previousGC.nurseryUsedBytes - - (sizeof(ChunkBase) * previousGC.nurseryUsedChunkCount))); + (NurseryChunkHeaderSize * previousGC.nurseryUsedChunkCount))); previousGC.reason = reason; previousGC.tenuredBytes = result.tenuredBytes; previousGC.tenuredCells = result.tenuredCells; - previousGC.nurseryUsedChunkCount = currentChunk_ + 1; + previousGC.nurseryUsedChunkCount = currentChunk() + 1; } // Resize the nursery. maybeResizeNursery(options, reason); - // Poison/initialise the first chunk. - if (previousGC.nurseryUsedBytes) { - // In most cases Nursery::clear() has not poisoned this chunk or marked it - // as NoAccess; so we only need to poison the region used during the last - // cycle. Also, if the heap was recently expanded we don't want to - // re-poison the new memory. In both cases we only need to poison until - // previousGC.nurseryUsedBytes. - // - // In cases where this is not true, like generational zeal mode or subchunk - // mode, poisonAndInitCurrentChunk() will ignore its parameter. It will - // also clamp the parameter. - poisonAndInitCurrentChunk(previousGC.nurseryUsedBytes); + if (!semispaceEnabled()) { + poisonAndInitCurrentChunk(); } bool validPromotionRate; @@ -1207,19 +1294,10 @@ void js::Nursery::collect(JS::GCOptions options, JS::GCReason reason) { startProfile(ProfileKey::Pretenure); size_t sitesPretenured = 0; - if (!wasEmpty) { - sitesPretenured = - doPretenuring(rt, reason, validPromotionRate, promotionRate); - } + sitesPretenured = + doPretenuring(rt, reason, validPromotionRate, promotionRate); endProfile(ProfileKey::Pretenure); - // We ignore gcMaxBytes when allocating for minor collection. However, if we - // overflowed, we disable the nursery. The next time we allocate, we'll fail - // because bytes >= gcMaxBytes. - if (gc->heapSize.bytes() >= tunables().gcMaxBytes()) { - disable(); - } - previousGC.endTime = TimeStamp::Now(); // Must happen after maybeResizeNursery. endProfile(ProfileKey::Total); @@ -1268,7 +1346,7 @@ void js::Nursery::sendTelemetry(JS::GCReason reason, TimeDuration totalTime, rt->metrics().GC_MINOR_REASON_LONG(uint32_t(reason)); } rt->metrics().GC_MINOR_US(totalTime); - rt->metrics().GC_NURSERY_BYTES_2(committed()); + rt->metrics().GC_NURSERY_BYTES_2(totalCommitted()); if (!wasEmpty) { rt->metrics().GC_PRETENURE_COUNT_2(sitesPretenured); @@ -1289,14 +1367,30 @@ void js::Nursery::printDeduplicationData(js::StringStats& prev, } } -void js::Nursery::freeTrailerBlocks(void) { +void js::Nursery::freeTrailerBlocks(JS::GCOptions options, + JS::GCReason reason) { + fromSpace.freeTrailerBlocks(mallocedBlockCache_); + + if (options == JS::GCOptions::Shrink || gc::IsOOMReason(reason)) { + mallocedBlockCache_.clear(); + return; + } + + // Discard blocks from the cache at 0.05% per megabyte of nursery capacity, + // that is, 0.8% of blocks for a 16-megabyte nursery. This allows the cache + // to gradually discard unneeded blocks in long running applications. + mallocedBlockCache_.preen(0.05 * double(capacity()) / (1024.0 * 1024.0)); +} + +void js::Nursery::Space::freeTrailerBlocks( + MallocedBlockCache& mallocedBlockCache) { // This routine frees those blocks denoted by the set // // trailersAdded_ (all of it) // - trailersRemoved_ (entries with index below trailersRemovedUsed_) // // For each block, places it back on the nursery's small-malloced-block pool - // by calling mallocedBlockCache_.free. + // by calling mallocedBlockCache.free. MOZ_ASSERT(trailersAdded_.length() == trailersRemoved_.length()); MOZ_ASSERT(trailersRemovedUsed_ <= trailersRemoved_.length()); @@ -1321,7 +1415,7 @@ void js::Nursery::freeTrailerBlocks(void) { if (!std::binary_search(trailersRemoved_.begin(), trailersRemoved_.begin() + trailersRemovedUsed_, blockPointer)) { - mallocedBlockCache_.free(block); + mallocedBlockCache.free(block); } } } else { @@ -1348,7 +1442,7 @@ void js::Nursery::freeTrailerBlocks(void) { const PointerAndUint7 blockAdded = trailersAdded_[iAdded]; const void* blockRemoved = trailersRemoved_[iRemoved]; if (blockAdded.pointer() < blockRemoved) { - mallocedBlockCache_.free(blockAdded); + mallocedBlockCache.free(blockAdded); continue; } // If this doesn't hold @@ -1362,7 +1456,7 @@ void js::Nursery::freeTrailerBlocks(void) { // added set. for (/*keep going*/; iAdded < nAdded; iAdded++) { const PointerAndUint7 block = trailersAdded_[iAdded]; - mallocedBlockCache_.free(block); + mallocedBlockCache.free(block); } } @@ -1371,17 +1465,14 @@ void js::Nursery::freeTrailerBlocks(void) { trailersRemoved_.clear(); trailersRemovedUsed_ = 0; trailerBytes_ = 0; - - // Discard blocks from the cache at 0.05% per megabyte of nursery capacity, - // that is, 0.8% of blocks for a 16-megabyte nursery. This allows the cache - // to gradually discard unneeded blocks in long running applications. - mallocedBlockCache_.preen(0.05 * double(capacity()) / (1024.0 * 1024.0)); } size_t Nursery::sizeOfTrailerBlockSets( mozilla::MallocSizeOf mallocSizeOf) const { - return trailersAdded_.sizeOfExcludingThis(mallocSizeOf) + - trailersRemoved_.sizeOfExcludingThis(mallocSizeOf); + MOZ_ASSERT(fromSpace.trailersAdded_.empty()); + MOZ_ASSERT(fromSpace.trailersRemoved_.empty()); + return toSpace.trailersAdded_.sizeOfExcludingThis(mallocSizeOf) + + toSpace.trailersRemoved_.sizeOfExcludingThis(mallocSizeOf); } js::Nursery::CollectionResult js::Nursery::doCollection(AutoGCSession& session, @@ -1393,8 +1484,19 @@ js::Nursery::CollectionResult js::Nursery::doCollection(AutoGCSession& session, AutoDisableProxyCheck disableStrictProxyChecking; mozilla::DebugOnly<AutoEnterOOMUnsafeRegion> oomUnsafeRegion; + // Swap nursery spaces. + swapSpaces(); + MOZ_ASSERT(toSpace.isEmpty()); + MOZ_ASSERT(toSpace.mallocedBuffers.empty()); + if (semispaceEnabled_) { + poisonAndInitCurrentChunk(); + } + + clearMapAndSetNurseryRanges(); + // Move objects pointed to by roots from the nursery to the major heap. - TenuringTracer mover(rt, this); + tenuredEverything = shouldTenureEverything(reason); + TenuringTracer mover(rt, this, tenuredEverything); // Trace everything considered as a root by a minor GC. traceRoots(session, mover); @@ -1433,17 +1535,14 @@ js::Nursery::CollectionResult js::Nursery::doCollection(AutoGCSession& session, // Sweep. startProfile(ProfileKey::FreeMallocedBuffers); - gc->queueBuffersForFreeAfterMinorGC(mallocedBuffers); - mallocedBufferBytes = 0; + gc->queueBuffersForFreeAfterMinorGC(fromSpace.mallocedBuffers); + fromSpace.mallocedBufferBytes = 0; endProfile(ProfileKey::FreeMallocedBuffers); // Give trailer blocks associated with non-tenured Wasm{Struct,Array}Objects // back to our `mallocedBlockCache_`. startProfile(ProfileKey::FreeTrailerBlocks); - freeTrailerBlocks(); - if (options == JS::GCOptions::Shrink || gc::IsOOMReason(reason)) { - mallocedBlockCache_.clear(); - } + freeTrailerBlocks(options, reason); endProfile(ProfileKey::FreeTrailerBlocks); startProfile(ProfileKey::ClearNursery); @@ -1466,7 +1565,28 @@ js::Nursery::CollectionResult js::Nursery::doCollection(AutoGCSession& session, #endif endProfile(ProfileKey::CheckHashTables); - return {mover.getTenuredSize(), mover.getTenuredCells()}; + if (semispaceEnabled_) { + // On the next collection, tenure everything before |tenureThreshold_|. + tenureThreshold_ = toSpace.offsetFromExclusiveAddress(position()); + } else { + // Swap nursery spaces back because we only use one. + swapSpaces(); + MOZ_ASSERT(toSpace.isEmpty()); + } + + MOZ_ASSERT(fromSpace.isEmpty()); + + if (semispaceEnabled_) { + poisonAndInitCurrentChunk(); + } + + return {mover.getPromotedSize(), mover.getPromotedCells()}; +} + +void js::Nursery::swapSpaces() { + std::swap(toSpace, fromSpace); + toSpace.setKind(ChunkKind::NurseryToSpace); + fromSpace.setKind(ChunkKind::NurseryFromSpace); } void js::Nursery::traceRoots(AutoGCSession& session, TenuringTracer& mover) { @@ -1490,14 +1610,12 @@ void js::Nursery::traceRoots(AutoGCSession& session, TenuringTracer& mover) { MOZ_ASSERT(gc->storeBuffer().isEnabled()); MOZ_ASSERT(gc->storeBuffer().isEmpty()); - // Strings in the whole cell buffer must be traced first, in order to mark - // tenured dependent strings' bases as non-deduplicatable. The rest of - // nursery collection (whole non-string cells, edges, etc.) can happen - // later. startProfile(ProfileKey::TraceWholeCells); sb.traceWholeCells(mover); endProfile(ProfileKey::TraceWholeCells); + cellsToSweep = sb.releaseCellSweepSet(); + startProfile(ProfileKey::TraceValues); sb.traceValues(mover); endProfile(ProfileKey::TraceValues); @@ -1523,8 +1641,6 @@ void js::Nursery::traceRoots(AutoGCSession& session, TenuringTracer& mover) { endProfile(ProfileKey::MarkRuntime); } - MOZ_ASSERT(gc->storeBuffer().isEmpty()); - startProfile(ProfileKey::MarkDebugger); { gcstats::AutoPhase ap(stats(), gcstats::PhaseKind::MARK_ROOTS); @@ -1533,6 +1649,15 @@ void js::Nursery::traceRoots(AutoGCSession& session, TenuringTracer& mover) { endProfile(ProfileKey::MarkDebugger); } +bool js::Nursery::shouldTenureEverything(JS::GCReason reason) { + if (!semispaceEnabled()) { + return true; + } + + return reason == JS::GCReason::EVICT_NURSERY || + reason == JS::GCReason::DISABLE_GENERATIONAL_GC; +} + size_t js::Nursery::doPretenuring(JSRuntime* rt, JS::GCReason reason, bool validPromotionRate, double promotionRate) { @@ -1590,12 +1715,13 @@ bool js::Nursery::registerMallocedBuffer(void* buffer, size_t nbytes) { MOZ_ASSERT(buffer); MOZ_ASSERT(nbytes > 0); MOZ_ASSERT(!isInside(buffer)); - if (!mallocedBuffers.putNew(buffer)) { + + if (!toSpace.mallocedBuffers.putNew(buffer)) { return false; } - mallocedBufferBytes += nbytes; - if (MOZ_UNLIKELY(mallocedBufferBytes > capacity() * 8)) { + toSpace.mallocedBufferBytes += nbytes; + if (MOZ_UNLIKELY(toSpace.mallocedBufferBytes > capacity() * 8)) { requestMinorGC(JS::GCReason::NURSERY_MALLOC_BUFFERS); } @@ -1613,21 +1739,19 @@ bool js::Nursery::registerMallocedBuffer(void* buffer, size_t nbytes) { Nursery::WasBufferMoved js::Nursery::maybeMoveRawBufferOnPromotion( void** bufferp, gc::Cell* owner, size_t nbytes, MemoryUse use, arena_id_t arena) { - MOZ_ASSERT(!IsInsideNursery(owner)); - void* buffer = *bufferp; if (!isInside(buffer)) { - // This is a malloced buffer. Remove it from the nursery's list of buffers - // so we don't free it and add it to the memory accounting for the zone + // This is a malloced buffer. Remove it from the nursery's previous list of + // buffers so we don't free it. removeMallocedBufferDuringMinorGC(buffer); - AddCellMemory(owner, nbytes, use); + trackMallocedBufferOnPromotion(buffer, owner, nbytes, use); return BufferNotMoved; } // Copy the nursery-allocated buffer into a new malloc allocation. AutoEnterOOMUnsafeRegion oomUnsafe; - Zone* zone = owner->asTenured().zone(); + Zone* zone = owner->zone(); void* movedBuffer = zone->pod_arena_malloc<uint8_t>(arena, nbytes); if (!movedBuffer) { oomUnsafe.crash("Nursery::updateBufferOnPromotion"); @@ -1635,38 +1759,111 @@ Nursery::WasBufferMoved js::Nursery::maybeMoveRawBufferOnPromotion( memcpy(movedBuffer, buffer, nbytes); - AddCellMemory(owner, nbytes, use); + trackMallocedBufferOnPromotion(movedBuffer, owner, nbytes, use); *bufferp = movedBuffer; return BufferMoved; } +void js::Nursery::trackMallocedBufferOnPromotion(void* buffer, gc::Cell* owner, + size_t nbytes, MemoryUse use) { + if (owner->isTenured()) { + // If we tenured the owner then account for the memory. + AddCellMemory(owner, nbytes, use); + return; + } + + // Otherwise add it to the nursery's new buffer list. + AutoEnterOOMUnsafeRegion oomUnsafe; + if (!registerMallocedBuffer(buffer, nbytes)) { + oomUnsafe.crash("Nursery::trackMallocedBufferOnPromotion"); + } +} + +void js::Nursery::trackTrailerOnPromotion(void* buffer, gc::Cell* owner, + size_t nbytes, size_t overhead, + MemoryUse use) { + MOZ_ASSERT(!isInside(buffer)); + unregisterTrailer(buffer); + + if (owner->isTenured()) { + // If we tenured the owner then account for the memory. + AddCellMemory(owner, nbytes + overhead, use); + return; + } + + // Otherwise add it to the nursery's new buffer list. + PointerAndUint7 blockAndListID(buffer, + MallocedBlockCache::listIDForSize(nbytes)); + AutoEnterOOMUnsafeRegion oomUnsafe; + if (!registerTrailer(blockAndListID, nbytes)) { + oomUnsafe.crash("Nursery::trackTrailerOnPromotion"); + } +} + void Nursery::requestMinorGC(JS::GCReason reason) { + JS::HeapState heapState = runtime()->heapState(); +#ifdef DEBUG + if (heapState == JS::HeapState::Idle || + heapState == JS::HeapState::MinorCollecting) { + MOZ_ASSERT(CurrentThreadCanAccessRuntime(runtime())); + } else if (heapState == JS::HeapState::MajorCollecting) { + // The GC runs sweeping tasks that may access the storebuffer in parallel + // and these require taking the store buffer lock. + MOZ_ASSERT(CurrentThreadIsGCSweeping()); + runtime()->gc.assertCurrentThreadHasLockedStoreBuffer(); + } else { + MOZ_CRASH("Unexpected heap state"); + } +#endif + MOZ_ASSERT(reason != JS::GCReason::NO_REASON); - MOZ_ASSERT(CurrentThreadCanAccessRuntime(runtime())); MOZ_ASSERT(isEnabled()); if (minorGCRequested()) { return; } + if (heapState == JS::HeapState::MinorCollecting) { + // This can happen when we promote a lot of data to the second generation in + // a semispace collection. This can trigger a GC due to the amount of store + // buffer entries added. + return; + } + // Set position to end of chunk to block further allocation. MOZ_ASSERT(prevPosition_ == 0); - prevPosition_ = position_; - position_ = chunk(currentChunk_).end(); + prevPosition_ = position(); + toSpace.position_ = chunk(currentChunk()).end(); minorGCTriggerReason_ = reason; - runtime()->mainContextFromOwnThread()->requestInterrupt( + runtime()->mainContextFromAnyThread()->requestInterrupt( InterruptReason::MinorGC); } +size_t SemispaceSizeFactor(bool semispaceEnabled) { + return semispaceEnabled ? 2 : 1; +} + +size_t js::Nursery::totalCapacity() const { + return capacity() * SemispaceSizeFactor(semispaceEnabled_); +} + +size_t js::Nursery::totalCommitted() const { + size_t size = std::min(capacity_, allocatedChunkCount() * gc::ChunkSize); + return size * SemispaceSizeFactor(semispaceEnabled_); +} + size_t Nursery::sizeOfMallocedBuffers( mozilla::MallocSizeOf mallocSizeOf) const { + MOZ_ASSERT(fromSpace.mallocedBuffers.empty()); + size_t total = 0; - for (BufferSet::Range r = mallocedBuffers.all(); !r.empty(); r.popFront()) { + for (BufferSet::Range r = toSpace.mallocedBuffers.all(); !r.empty(); + r.popFront()) { total += mallocSizeOf(r.front()); } - total += mallocedBuffers.shallowSizeOfExcludingThis(mallocSizeOf); + total += toSpace.mallocedBuffers.shallowSizeOfExcludingThis(mallocSizeOf); return total; } @@ -1680,121 +1877,171 @@ void js::Nursery::sweep() { // Sweep unique IDs first before we sweep any tables that may be keyed based // on them. - for (Cell* cell : cellsWithUid_) { + cellsWithUid_.mutableEraseIf([](Cell*& cell) { auto* obj = static_cast<JSObject*>(cell); if (!IsForwarded(obj)) { gc::RemoveUniqueId(obj); - } else { - JSObject* dst = Forwarded(obj); - gc::TransferUniqueId(dst, obj); + return true; } - } - cellsWithUid_.clear(); + + JSObject* dst = Forwarded(obj); + gc::TransferUniqueId(dst, obj); + + if (!IsInsideNursery(dst)) { + return true; + } + + cell = dst; + return false; + }); for (ZonesIter zone(runtime(), SkipAtoms); !zone.done(); zone.next()) { zone->sweepAfterMinorGC(&trc); } sweepMapAndSetObjects(); + cellsToSweep.sweep(); + CellSweepSet empty; + std::swap(cellsToSweep, empty); runtime()->caches().sweepAfterMinorGC(&trc); } +void gc::CellSweepSet::sweep() { + if (head_) { + head_->sweepDependentStrings(); + head_ = nullptr; + } + if (storage_) { + storage_->freeAll(); + } +} + void js::Nursery::clear() { + fromSpace.clear(this); + MOZ_ASSERT(fromSpace.isEmpty()); +} + +void js::Nursery::Space::clear(Nursery* nursery) { + GCRuntime* gc = nursery->gc; + // Poison the nursery contents so touching a freed object will crash. unsigned firstClearChunk; - if (gc->hasZealMode(ZealMode::GenerationalGC)) { - // Poison all the chunks used in this cycle. The new start chunk is - // reposioned in Nursery::collect() but there's no point optimising that in - // this case. + if (gc->hasZealMode(ZealMode::GenerationalGC) || nursery->semispaceEnabled_) { + // Poison all the chunks used in this cycle. firstClearChunk = startChunk_; } else { - // In normal mode we start at the second chunk, the first one will be used + // Poison from the second chunk onwards as the first one will be used // in the next cycle and poisoned in Nusery::collect(); MOZ_ASSERT(startChunk_ == 0); firstClearChunk = 1; } for (unsigned i = firstClearChunk; i < currentChunk_; ++i) { - chunk(i).poisonAfterEvict(); + chunks_[i]->poisonAfterEvict(); } // Clear only the used part of the chunk because that's the part we touched, // but only if it's not going to be re-used immediately (>= firstClearChunk). if (currentChunk_ >= firstClearChunk) { - chunk(currentChunk_) - .poisonAfterEvict(position() - chunk(currentChunk_).start()); + size_t usedBytes = position_ - chunks_[currentChunk_]->start(); + chunks_[currentChunk_]->poisonAfterEvict(NurseryChunkHeaderSize + + usedBytes); } // Reset the start chunk & position if we're not in this zeal mode, or we're // in it and close to the end of the nursery. - MOZ_ASSERT(maxChunkCount() > 0); + MOZ_ASSERT(maxChunkCount_ > 0); if (!gc->hasZealMode(ZealMode::GenerationalGC) || - (gc->hasZealMode(ZealMode::GenerationalGC) && - currentChunk_ + 1 == maxChunkCount())) { - moveToStartOfChunk(0); + currentChunk_ + 1 == maxChunkCount_) { + moveToStartOfChunk(nursery, 0); } // Set current start position for isEmpty checks. setStartToCurrentPosition(); } -MOZ_ALWAYS_INLINE void js::Nursery::moveToStartOfChunk(unsigned chunkno) { - MOZ_ASSERT(chunkno < allocatedChunkCount()); +void js::Nursery::moveToStartOfChunk(unsigned chunkno) { + toSpace.moveToStartOfChunk(this, chunkno); +} + +void js::Nursery::Space::moveToStartOfChunk(Nursery* nursery, + unsigned chunkno) { + MOZ_ASSERT(chunkno < chunks_.length()); currentChunk_ = chunkno; - position_ = chunk(chunkno).start(); - setCurrentEnd(); + position_ = chunks_[chunkno]->start(); + setCurrentEnd(nursery); MOZ_ASSERT(position_ != 0); MOZ_ASSERT(currentEnd_ > position_); // Check this cannot wrap. } -void js::Nursery::poisonAndInitCurrentChunk(size_t extent) { - if (gc->hasZealMode(ZealMode::GenerationalGC) || !isSubChunkMode()) { - chunk(currentChunk_).poisonAndInit(runtime()); - } else { - extent = std::min(capacity_, extent); - chunk(currentChunk_).poisonAndInit(runtime(), extent); - } +void js::Nursery::poisonAndInitCurrentChunk() { + NurseryChunk& chunk = this->chunk(currentChunk()); + size_t start = position() - uintptr_t(&chunk); + size_t end = isSubChunkMode() ? capacity_ : ChunkSize; + chunk.poisonRange(start, end, JS_FRESH_NURSERY_PATTERN, + MemCheckKind::MakeUndefined); + new (&chunk) + NurseryChunk(runtime(), ChunkKind::NurseryToSpace, currentChunk()); } -MOZ_ALWAYS_INLINE void js::Nursery::setCurrentEnd() { - MOZ_ASSERT_IF(isSubChunkMode(), - currentChunk_ == 0 && currentEnd_ <= chunk(0).end()); - currentEnd_ = - uintptr_t(&chunk(currentChunk_)) + std::min(capacity_, ChunkSize); +void js::Nursery::setCurrentEnd() { toSpace.setCurrentEnd(this); } - MOZ_ASSERT_IF(!isSubChunkMode(), currentEnd_ == chunk(currentChunk_).end()); - MOZ_ASSERT(currentEnd_ != chunk(currentChunk_).start()); +void js::Nursery::Space::setCurrentEnd(Nursery* nursery) { + currentEnd_ = uintptr_t(chunks_[currentChunk_]) + + std::min(nursery->capacity(), ChunkSize); } -bool js::Nursery::allocateNextChunk(const unsigned chunkno, - AutoLockGCBgAlloc& lock) { - const unsigned priorCount = allocatedChunkCount(); +bool js::Nursery::allocateNextChunk(AutoLockGCBgAlloc& lock) { + // Allocate a new nursery chunk. If semispace collection is enabled, we have + // to allocate one for both spaces. + + const unsigned priorCount = toSpace.chunks_.length(); const unsigned newCount = priorCount + 1; - MOZ_ASSERT((chunkno == currentChunk_ + 1) || - (chunkno == 0 && allocatedChunkCount() == 0)); - MOZ_ASSERT(chunkno == allocatedChunkCount()); - MOZ_ASSERT(chunkno < HowMany(capacity(), ChunkSize)); + MOZ_ASSERT(newCount <= maxChunkCount()); + MOZ_ASSERT(fromSpace.chunks_.length() == + (semispaceEnabled_ ? priorCount : 0)); + + if (!toSpace.chunks_.reserve(newCount) || + (semispaceEnabled_ && !fromSpace.chunks_.reserve(newCount))) { + return false; + } - if (!chunks_.resize(newCount)) { + TenuredChunk* toSpaceChunk = gc->getOrAllocChunk(lock); + if (!toSpaceChunk) { return false; } - TenuredChunk* newChunk; - newChunk = gc->getOrAllocChunk(lock); - if (!newChunk) { - chunks_.shrinkTo(priorCount); + TenuredChunk* fromSpaceChunk = nullptr; + if (semispaceEnabled_ && !(fromSpaceChunk = gc->getOrAllocChunk(lock))) { + gc->recycleChunk(toSpaceChunk, lock); return false; } - chunks_[chunkno] = NurseryChunk::fromChunk(newChunk); + uint8_t index = toSpace.chunks_.length(); + NurseryChunk* nurseryChunk = + NurseryChunk::fromChunk(toSpaceChunk, ChunkKind::NurseryToSpace, index); + toSpace.chunks_.infallibleAppend(nurseryChunk); + + if (semispaceEnabled_) { + MOZ_ASSERT(index == fromSpace.chunks_.length()); + nurseryChunk = NurseryChunk::fromChunk(fromSpaceChunk, + ChunkKind::NurseryFromSpace, index); + fromSpace.chunks_.infallibleAppend(nurseryChunk); + } + return true; } -MOZ_ALWAYS_INLINE void js::Nursery::setStartToCurrentPosition() { +void js::Nursery::setStartToCurrentPosition() { + toSpace.setStartToCurrentPosition(); +} + +void js::Nursery::Space::setStartToCurrentPosition() { startChunk_ = currentChunk_; - startPosition_ = position(); + startPosition_ = position_; + MOZ_ASSERT(isEmpty()); } void js::Nursery::maybeResizeNursery(JS::GCOptions options, @@ -1809,8 +2056,7 @@ void js::Nursery::maybeResizeNursery(JS::GCOptions options, decommitTask->join(); size_t newCapacity = mozilla::Clamp(targetSize(options, reason), - tunables().gcMinNurseryBytes(), - tunables().gcMaxNurseryBytes()); + minSpaceSize(), maxSpaceSize()); MOZ_ASSERT(roundSize(newCapacity) == newCapacity); MOZ_ASSERT(newCapacity >= SystemPageSize()); @@ -1862,7 +2108,7 @@ size_t js::Nursery::targetSize(JS::GCOptions options, JS::GCReason reason) { TimeStamp now = TimeStamp::Now(); if (reason == JS::GCReason::PREPARE_FOR_PAGELOAD) { - return roundSize(tunables().gcMaxNurseryBytes()); + return roundSize(maxSpaceSize()); } // If the nursery is completely unused then minimise it. @@ -1960,38 +2206,58 @@ size_t js::Nursery::roundSize(size_t size) { } void js::Nursery::growAllocableSpace(size_t newCapacity) { - MOZ_ASSERT_IF(!isSubChunkMode(), newCapacity > currentChunk_ * ChunkSize); - MOZ_ASSERT(newCapacity <= tunables().gcMaxNurseryBytes()); + MOZ_ASSERT_IF(!isSubChunkMode(), newCapacity > currentChunk() * ChunkSize); + MOZ_ASSERT(newCapacity <= maxSpaceSize()); MOZ_ASSERT(newCapacity > capacity()); - if (!decommitTask->reserveSpaceForBytes(newCapacity)) { + size_t nchunks = + RequiredChunkCount(newCapacity) * SemispaceSizeFactor(semispaceEnabled_); + if (!decommitTask->reserveSpaceForChunks(nchunks)) { return; } if (isSubChunkMode()) { - MOZ_ASSERT(currentChunk_ == 0); - - // The remainder of the chunk may have been decommitted. - if (!chunk(0).markPagesInUseHard(std::min(newCapacity, ChunkSize))) { - // The OS won't give us the memory we need, we can't grow. + if (!toSpace.commitSubChunkRegion(capacity(), newCapacity) || + (semispaceEnabled_ && + !fromSpace.commitSubChunkRegion(capacity(), newCapacity))) { return; } + } - // The capacity has changed and since we were in sub-chunk mode we need to - // update the poison values / asan information for the now-valid region of - // this chunk. - size_t end = std::min(newCapacity, ChunkSize); - chunk(0).poisonRange(capacity(), end, JS_FRESH_NURSERY_PATTERN, - MemCheckKind::MakeUndefined); + setCapacity(newCapacity); + + toSpace.setCurrentEnd(this); + if (semispaceEnabled_) { + fromSpace.setCurrentEnd(this); } +} - capacity_ = newCapacity; +bool js::Nursery::Space::commitSubChunkRegion(size_t oldCapacity, + size_t newCapacity) { + MOZ_ASSERT(currentChunk_ == 0); + MOZ_ASSERT(oldCapacity < ChunkSize); + MOZ_ASSERT(newCapacity > oldCapacity); - setCurrentEnd(); + size_t newChunkEnd = std::min(newCapacity, ChunkSize); + + // The remainder of the chunk may have been decommitted. + if (!chunks_[0]->markPagesInUseHard(newChunkEnd)) { + // The OS won't give us the memory we need, we can't grow. + return false; + } + + // The capacity has changed and since we were in sub-chunk mode we need to + // update the poison values / asan information for the now-valid region of + // this chunk. + chunks_[0]->poisonRange(oldCapacity, newChunkEnd, JS_FRESH_NURSERY_PATTERN, + MemCheckKind::MakeUndefined); + return true; } -void js::Nursery::freeChunksFrom(const unsigned firstFreeChunk) { - MOZ_ASSERT(firstFreeChunk < chunks_.length()); +void js::Nursery::freeChunksFrom(Space& space, const unsigned firstFreeChunk) { + if (firstFreeChunk >= space.chunks_.length()) { + return; + } // The loop below may need to skip the first chunk, so we may use this so we // can modify it. @@ -2000,61 +2266,112 @@ void js::Nursery::freeChunksFrom(const unsigned firstFreeChunk) { if ((firstChunkToDecommit == 0) && isSubChunkMode()) { // Part of the first chunk may be hard-decommitted, un-decommit it so that // the GC's normal chunk-handling doesn't segfault. - MOZ_ASSERT(currentChunk_ == 0); - if (!chunk(0).markPagesInUseHard(ChunkSize)) { + MOZ_ASSERT(space.currentChunk_ == 0); + if (!space.chunks_[0]->markPagesInUseHard(ChunkSize)) { // Free the chunk if we can't allocate its pages. - UnmapPages(static_cast<void*>(&chunk(0)), ChunkSize); + UnmapPages(space.chunks_[0], ChunkSize); firstChunkToDecommit = 1; } } { AutoLockHelperThreadState lock; - for (size_t i = firstChunkToDecommit; i < chunks_.length(); i++) { - decommitTask->queueChunk(chunks_[i], lock); + for (size_t i = firstChunkToDecommit; i < space.chunks_.length(); i++) { + decommitTask->queueChunk(space.chunks_[i], lock); } } - chunks_.shrinkTo(firstFreeChunk); + space.chunks_.shrinkTo(firstFreeChunk); } void js::Nursery::shrinkAllocableSpace(size_t newCapacity) { -#ifdef JS_GC_ZEAL - if (gc->hasZealMode(ZealMode::GenerationalGC)) { - return; - } -#endif + MOZ_ASSERT(!gc->hasZealMode(ZealMode::GenerationalGC)); + MOZ_ASSERT(newCapacity < capacity_); - // Don't shrink the nursery to zero (use Nursery::disable() instead) - // This can't happen due to the rounding-down performed above because of the - // clamping in maybeResizeNursery(). - MOZ_ASSERT(newCapacity != 0); - // Don't attempt to shrink it to the same size. - if (newCapacity == capacity_) { + if (semispaceEnabled() && usedSpace() >= newCapacity) { + // Can't shrink below what we've already used. return; } - MOZ_ASSERT(newCapacity < capacity_); unsigned newCount = HowMany(newCapacity, ChunkSize); if (newCount < allocatedChunkCount()) { - freeChunksFrom(newCount); + freeChunksFrom(toSpace, newCount); + freeChunksFrom(fromSpace, newCount); } size_t oldCapacity = capacity_; - capacity_ = newCapacity; + setCapacity(newCapacity); - setCurrentEnd(); + toSpace.setCurrentEnd(this); + if (semispaceEnabled_) { + fromSpace.setCurrentEnd(this); + } if (isSubChunkMode()) { - MOZ_ASSERT(currentChunk_ == 0); - size_t end = std::min(oldCapacity, ChunkSize); - chunk(0).poisonRange(newCapacity, end, JS_SWEPT_NURSERY_PATTERN, - MemCheckKind::MakeNoAccess); + toSpace.decommitSubChunkRegion(this, oldCapacity, newCapacity); + if (semispaceEnabled_) { + fromSpace.decommitSubChunkRegion(this, oldCapacity, newCapacity); + } + } +} - AutoLockHelperThreadState lock; - decommitTask->queueRange(capacity_, chunk(0), lock); +void js::Nursery::Space::decommitSubChunkRegion(Nursery* nursery, + size_t oldCapacity, + size_t newCapacity) { + MOZ_ASSERT(currentChunk_ == 0); + MOZ_ASSERT(newCapacity < ChunkSize); + MOZ_ASSERT(newCapacity < oldCapacity); + + size_t oldChunkEnd = std::min(oldCapacity, ChunkSize); + chunks_[0]->poisonRange(newCapacity, oldChunkEnd, JS_SWEPT_NURSERY_PATTERN, + MemCheckKind::MakeNoAccess); + + AutoLockHelperThreadState lock; + nursery->decommitTask->queueRange(newCapacity, chunks_[0], lock); +} + +js::Nursery::Space::Space(gc::ChunkKind kind) : kind(kind) { + MOZ_ASSERT(kind == ChunkKind::NurseryFromSpace || + kind == ChunkKind::NurseryToSpace); +} + +void js::Nursery::Space::setKind(ChunkKind newKind) { +#ifdef DEBUG + MOZ_ASSERT(newKind == ChunkKind::NurseryFromSpace || + newKind == ChunkKind::NurseryToSpace); + checkKind(kind); +#endif + + kind = newKind; + for (NurseryChunk* chunk : chunks_) { + chunk->kind = newKind; + } + +#ifdef DEBUG + checkKind(newKind); +#endif +} + +#ifdef DEBUG +void js::Nursery::Space::checkKind(ChunkKind expected) const { + MOZ_ASSERT(kind == expected); + for (NurseryChunk* chunk : chunks_) { + MOZ_ASSERT(chunk->getKind() == expected); + } +} +#endif + +#ifdef DEBUG +size_t js::Nursery::Space::findChunkIndex(uintptr_t chunkAddr) const { + for (size_t i = 0; i < chunks_.length(); i++) { + if (uintptr_t(chunks_[i]) == chunkAddr) { + return i; + } } + + MOZ_CRASH("Nursery chunk not found"); } +#endif gcstats::Statistics& js::Nursery::stats() const { return gc->stats(); } @@ -2067,18 +2384,55 @@ bool js::Nursery::isSubChunkMode() const { return capacity() <= NurseryChunkUsableSize; } +void js::Nursery::clearMapAndSetNurseryRanges() { + // Clears the lists of nursery ranges used by map and set iterators. These + // lists are cleared at the start of minor GC and rebuilt when iterators are + // promoted during minor GC. + for (auto* map : mapsWithNurseryMemory_) { + map->clearNurseryRangesBeforeMinorGC(); + } + for (auto* set : setsWithNurseryMemory_) { + set->clearNurseryRangesBeforeMinorGC(); + } +} + void js::Nursery::sweepMapAndSetObjects() { + // This processes all Map and Set objects that are known to have associated + // nursery memory (either they are nursery allocated themselves or they have + // iterator objects that are nursery allocated). + // + // These objects may die and be finalized or if not their internal state and + // memory tracking are updated. + // + // Finally the lists themselves are rebuilt so as to remove objects that are + // no longer associated with nursery memory (either because they died or + // because the nursery object was promoted to the tenured heap). + auto* gcx = runtime()->gcContext(); - for (auto* mapobj : mapsWithNurseryMemory_) { - MapObject::sweepAfterMinorGC(gcx, mapobj); + AutoEnterOOMUnsafeRegion oomUnsafe; + + MapObjectVector maps; + std::swap(mapsWithNurseryMemory_, maps); + for (auto* mapobj : maps) { + mapobj = MapObject::sweepAfterMinorGC(gcx, mapobj); + if (mapobj) { + if (!mapsWithNurseryMemory_.append(mapobj)) { + oomUnsafe.crash("sweepAfterMinorGC"); + } + } } - mapsWithNurseryMemory_.clearAndFree(); - for (auto* setobj : setsWithNurseryMemory_) { - SetObject::sweepAfterMinorGC(gcx, setobj); + SetObjectVector sets; + std::swap(setsWithNurseryMemory_, sets); + for (auto* setobj : sets) { + setobj = SetObject::sweepAfterMinorGC(gcx, setobj); + if (setobj) { + if (!setsWithNurseryMemory_.append(setobj)) { + oomUnsafe.crash("sweepAfterMinorGC"); + } + } } - setsWithNurseryMemory_.clearAndFree(); } void js::Nursery::joinDecommitTask() { decommitTask->join(); } diff --git a/js/src/gc/Nursery.h b/js/src/gc/Nursery.h index 0d7b607ff8..647dbbb24f 100644 --- a/js/src/gc/Nursery.h +++ b/js/src/gc/Nursery.h @@ -13,6 +13,7 @@ #include <tuple> +#include "ds/LifoAlloc.h" #include "gc/GCEnum.h" #include "gc/GCProbes.h" #include "gc/Heap.h" @@ -21,6 +22,8 @@ #include "js/AllocPolicy.h" #include "js/Class.h" #include "js/GCAPI.h" +#include "js/GCVector.h" +#include "js/HeapAPI.h" #include "js/TypeDecls.h" #include "js/UniquePtr.h" #include "js/Utility.h" @@ -69,7 +72,20 @@ namespace gc { class AutoGCSession; struct Cell; class GCSchedulingTunables; +class StoreBuffer; class TenuringTracer; + +// A set of cells that need to be swept at the end of a minor GC, +// represented as a linked list of ArenaCellSet structs extracted from a +// WholeCellBuffer. +struct CellSweepSet { + UniquePtr<LifoAlloc> storage_; + ArenaCellSet* head_ = nullptr; + + // Fixup the tenured dependent strings stored in the ArenaCellSet list. + void sweep(); +}; + } // namespace gc class Nursery { @@ -79,18 +95,6 @@ class Nursery { [[nodiscard]] bool init(AutoLockGCBgAlloc& lock); - // Number of allocated (ready to use) chunks. - unsigned allocatedChunkCount() const { return chunks_.length(); } - - // Total number of chunks and the capacity of the nursery. Chunks will be - // lazilly allocated and added to the chunks array up to this limit, after - // that the nursery must be collected, this limit may be raised during - // collection. - unsigned maxChunkCount() const { - MOZ_ASSERT(capacity()); - return HowMany(capacity(), gc::ChunkSize); - } - void enable(); void disable(); bool isEnabled() const { return capacity() != 0; } @@ -103,20 +107,16 @@ class Nursery { void disableBigInts(); bool canAllocateBigInts() const { return canAllocateBigInts_; } + void setSemispaceEnabled(bool enabled); + bool semispaceEnabled() const { return semispaceEnabled_; } + // Return true if no allocations have been made since the last collection. bool isEmpty() const; // Check whether an arbitrary pointer is within the nursery. This is // slower than IsInsideNursery(Cell*), but works on all types of pointers. - MOZ_ALWAYS_INLINE bool isInside(gc::Cell* cellp) const = delete; - MOZ_ALWAYS_INLINE bool isInside(const void* p) const { - for (auto* chunk : chunks_) { - if (uintptr_t(p) - uintptr_t(chunk) < gc::ChunkSize) { - return true; - } - } - return false; - } + bool isInside(gc::Cell* cellp) const = delete; + inline bool isInside(const void* p) const; template <typename T> inline bool isInside(const SharedMem<T>& p) const; @@ -223,11 +223,12 @@ class Nursery { // Mark a malloced buffer as no longer needing to be freed. void removeMallocedBuffer(void* buffer, size_t nbytes) { - MOZ_ASSERT(mallocedBuffers.has(buffer)); + MOZ_ASSERT(!JS::RuntimeHeapIsMinorCollecting()); + MOZ_ASSERT(toSpace.mallocedBuffers.has(buffer)); MOZ_ASSERT(nbytes > 0); - MOZ_ASSERT(mallocedBufferBytes >= nbytes); - mallocedBuffers.remove(buffer); - mallocedBufferBytes -= nbytes; + MOZ_ASSERT(toSpace.mallocedBufferBytes >= nbytes); + toSpace.mallocedBuffers.remove(buffer); + toSpace.mallocedBufferBytes -= nbytes; } // Mark a malloced buffer as no longer needing to be freed during minor @@ -235,8 +236,8 @@ class Nursery { // buffers will soon be freed. void removeMallocedBufferDuringMinorGC(void* buffer) { MOZ_ASSERT(JS::RuntimeHeapIsMinorCollecting()); - MOZ_ASSERT(mallocedBuffers.has(buffer)); - mallocedBuffers.remove(buffer); + MOZ_ASSERT(fromSpace.mallocedBuffers.has(buffer)); + fromSpace.mallocedBuffers.remove(buffer); } [[nodiscard]] bool addedUniqueIdToCell(gc::Cell* cell) { @@ -277,26 +278,8 @@ class Nursery { inline void unregisterTrailer(void* block); size_t sizeOfTrailerBlockSets(mozilla::MallocSizeOf mallocSizeOf) const; - size_t capacity() const { return capacity_; } - size_t committed() const { - return std::min(capacity_, allocatedChunkCount() * gc::ChunkSize); - } - - // Used and free space both include chunk headers for that part of the - // nursery. - // - // usedSpace() + freeSpace() == capacity() - // - MOZ_ALWAYS_INLINE size_t usedSpace() const { - return capacity() - freeSpace(); - } - MOZ_ALWAYS_INLINE size_t freeSpace() const { - MOZ_ASSERT(isEnabled()); - MOZ_ASSERT(currentEnd_ - position_ <= NurseryChunkUsableSize); - MOZ_ASSERT(currentChunk_ < maxChunkCount()); - return (currentEnd_ - position_) + - (maxChunkCount() - currentChunk_ - 1) * gc::ChunkSize; - } + size_t totalCapacity() const; + size_t totalCommitted() const; #ifdef JS_GC_ZEAL void enterZealMode(); @@ -312,9 +295,10 @@ class Nursery { // Print total profile times on shutdown. void printTotalProfileTimes(); - void* addressOfPosition() const { return (void**)&position_; } + void* addressOfPosition() const { return (void**)&toSpace.position_; } static constexpr int32_t offsetOfCurrentEndFromPosition() { - return offsetof(Nursery, currentEnd_) - offsetof(Nursery, position_); + return offsetof(Nursery, toSpace.currentEnd_) - + offsetof(Nursery, toSpace.position_); } void* addressOfNurseryAllocatedSites() { @@ -343,10 +327,6 @@ class Nursery { return setsWithNurseryMemory_.append(obj); } - // The amount of space in the mapped nursery available to allocations. - static const size_t NurseryChunkUsableSize = - gc::ChunkSize - sizeof(gc::ChunkBase); - void joinDecommitTask(); mozilla::TimeStamp collectionStartTime() { @@ -362,6 +342,16 @@ class Nursery { void setAllocFlagsForZone(JS::Zone* zone); + bool shouldTenureEverything(JS::GCReason reason); + + inline bool inCollectedRegion(gc::Cell* cell) const; + inline bool inCollectedRegion(void* ptr) const; + + void trackMallocedBufferOnPromotion(void* buffer, gc::Cell* owner, + size_t nbytes, MemoryUse use); + void trackTrailerOnPromotion(void* buffer, gc::Cell* owner, size_t nbytes, + size_t overhead, MemoryUse use); + // Round a size in bytes to the nearest valid nursery size. static size_t roundSize(size_t size); @@ -374,6 +364,8 @@ class Nursery { mozilla::TimeStamp lastCollectionEndTime() const; private: + struct Space; + enum class ProfileKey { #define DEFINE_TIME_KEY(name, text) name, FOR_EACH_NURSERY_PROFILE_TIME(DEFINE_TIME_KEY) @@ -387,6 +379,36 @@ class Nursery { mozilla::EnumeratedArray<ProfileKey, mozilla::TimeDuration, size_t(ProfileKey::KeyCount)>; + size_t capacity() const { return capacity_; } + + // Total number of chunks and the capacity of the current nursery + // space. Chunks will be lazily allocated and added to the chunks array up to + // this limit. After that the nursery must be collected. This limit may be + // changed at the end of collection by maybeResizeNursery. + uint32_t maxChunkCount() const { + MOZ_ASSERT(toSpace.maxChunkCount_); + return toSpace.maxChunkCount_; + } + + // Number of allocated (ready to use) chunks. + unsigned allocatedChunkCount() const { return toSpace.chunks_.length(); } + + uint32_t currentChunk() const { return toSpace.currentChunk_; } + uint32_t startChunk() const { return toSpace.startChunk_; } + uintptr_t startPosition() const { return toSpace.startPosition_; } + + // Used and free space both include chunk headers for that part of the + // nursery. + MOZ_ALWAYS_INLINE size_t usedSpace() const { + return capacity() - freeSpace(); + } + MOZ_ALWAYS_INLINE size_t freeSpace() const { + MOZ_ASSERT(isEnabled()); + MOZ_ASSERT(currentChunk() < maxChunkCount()); + return (currentEnd() - position()) + + (maxChunkCount() - currentChunk() - 1) * gc::ChunkSize; + } + // Calculate the promotion rate of the most recent minor GC. // The valid_for_tenuring parameter is used to return whether this // promotion rate is accurate enough (the nursery was full enough) to be @@ -395,31 +417,27 @@ class Nursery { // Must only be called if the previousGC data is initialised. double calcPromotionRate(bool* validForTenuring) const; - void freeTrailerBlocks(); + void freeTrailerBlocks(JS::GCOptions options, JS::GCReason reason); - NurseryChunk& chunk(unsigned index) const { return *chunks_[index]; } + NurseryChunk& chunk(unsigned index) const { return *toSpace.chunks_[index]; } // Set the allocation position to the start of a chunk. This sets // currentChunk_, position_ and currentEnd_ values as appropriate. void moveToStartOfChunk(unsigned chunkno); bool initFirstChunk(AutoLockGCBgAlloc& lock); + void setCapacity(size_t newCapacity); - // extent is advisory, it will be ignored in sub-chunk and generational zeal - // modes. It will be clamped to Min(NurseryChunkUsableSize, capacity_). - void poisonAndInitCurrentChunk(size_t extent = gc::ChunkSize); + void poisonAndInitCurrentChunk(); void setCurrentEnd(); void setStartToCurrentPosition(); - // Allocate the next chunk, or the first chunk for initialization. - // Callers will probably want to call moveToStartOfChunk(0) next. - [[nodiscard]] bool allocateNextChunk(unsigned chunkno, - AutoLockGCBgAlloc& lock); + // Allocate another chunk. + [[nodiscard]] bool allocateNextChunk(AutoLockGCBgAlloc& lock); - uintptr_t currentEnd() const { return currentEnd_; } - - uintptr_t position() const { return position_; } + uintptr_t position() const { return toSpace.position_; } + uintptr_t currentEnd() const { return toSpace.currentEnd_; } MOZ_ALWAYS_INLINE bool isSubChunkMode() const; @@ -451,6 +469,7 @@ class Nursery { }; CollectionResult doCollection(gc::AutoGCSession& session, JS::GCOptions options, JS::GCReason reason); + void swapSpaces(); void traceRoots(gc::AutoGCSession& session, gc::TenuringTracer& mover); size_t doPretenuring(JSRuntime* rt, JS::GCReason reason, @@ -469,22 +488,30 @@ class Nursery { uint32_t capacity); #ifdef DEBUG - bool checkForwardingPointerLocation(void* ptr, bool expectedInside); + bool checkForwardingPointerInsideNursery(void* ptr); #endif // Updates pointers to nursery objects that have been tenured and discards // pointers to objects that have been freed. void sweep(); - // Reset the current chunk and position after a minor collection. Also poison + // In a minor GC, resets the start and end positions, the current chunk and + // current position. + void setNewExtentAndPosition(); + // the nursery on debug & nightly builds. void clear(); + void clearMapAndSetNurseryRanges(); void sweepMapAndSetObjects(); // Allocate a buffer for a given zone, using the nursery if possible. void* allocateBuffer(JS::Zone* zone, size_t nbytes); + // Get per-space size limits. + size_t maxSpaceSize() const; + size_t minSpaceSize() const; + // Change the allocable space provided by the nursery. void maybeResizeNursery(JS::GCOptions options, JS::GCReason reason); size_t targetSize(JS::GCOptions options, JS::GCReason reason); @@ -495,7 +522,9 @@ class Nursery { // Free the chunks starting at firstFreeChunk until the end of the chunks // vector. Shrinks the vector but does not update maxChunkCount(). - void freeChunksFrom(unsigned firstFreeChunk); + void freeChunksFrom(Space& space, unsigned firstFreeChunk); + + inline bool shouldTenure(gc::Cell* cell); void sendTelemetry(JS::GCReason reason, mozilla::TimeDuration totalTime, bool wasEmpty, double promotionRate, @@ -514,35 +543,87 @@ class Nursery { mozilla::TimeStamp collectionStartTime() const; private: - // Fields used during allocation fast path are grouped first: + using BufferRelocationOverlay = void*; + using BufferSet = HashSet<void*, PointerHasher<void*>, SystemAllocPolicy>; - // Pointer to the first unallocated byte in the nursery. - uintptr_t position_; + struct Space { + // Fields used during allocation fast path go first: - // Pointer to the last byte of space in the current chunk. - uintptr_t currentEnd_; + // Pointer to the first unallocated byte in the nursery. + uintptr_t position_ = 0; - // Other fields not necessarily used during allocation follow: + // Pointer to the last byte of space in the current chunk. + uintptr_t currentEnd_ = 0; - gc::GCRuntime* const gc; + // Vector of allocated chunks to allocate from. + Vector<NurseryChunk*, 0, SystemAllocPolicy> chunks_; + + // The index of the chunk that is currently being allocated from. + uint32_t currentChunk_ = 0; + + // The maximum number of chunks to allocate based on capacity_. + uint32_t maxChunkCount_ = 0; + + // These fields refer to the beginning of the nursery. They're normally 0 + // and chunk(0).start() respectively. Except when a generational GC zeal + // mode is active, then they may be arbitrary (see Nursery::clear()). + uint32_t startChunk_ = 0; + uintptr_t startPosition_ = 0; + + // The set of malloced-allocated buffers owned by nursery objects. Any + // buffers that do not belong to a promoted thing at the end of a minor GC + // must be freed. + BufferSet mallocedBuffers; + size_t mallocedBufferBytes = 0; + + // Wasm "trailer" (C++-heap-allocated) blocks. See comments above on + // ::registerTrailer and ::unregisterTrailer. + Vector<PointerAndUint7, 0, SystemAllocPolicy> trailersAdded_; + Vector<void*, 0, SystemAllocPolicy> trailersRemoved_; + size_t trailersRemovedUsed_ = 0; + size_t trailerBytes_ = 0; + + gc::ChunkKind kind; + + explicit Space(gc::ChunkKind kind); + + inline bool isEmpty() const; + inline bool isInside(const void* p) const; - // Vector of allocated chunks to allocate from. - Vector<NurseryChunk*, 0, SystemAllocPolicy> chunks_; + // Return the logical offset within the nursery of an address in a nursery + // chunk (chunks are discontiguous in memory). + inline size_t offsetFromAddress(uintptr_t addr) const; + inline size_t offsetFromExclusiveAddress(uintptr_t addr) const; - // The index of the chunk that is currently being allocated from. - uint32_t currentChunk_; + void setKind(gc::ChunkKind newKind); - // These fields refer to the beginning of the nursery. They're normally 0 - // and chunk(0).start() respectively. Except when a generational GC zeal - // mode is active, then they may be arbitrary (see Nursery::clear()). - uint32_t startChunk_; - uintptr_t startPosition_; + void clear(Nursery* nursery); + void moveToStartOfChunk(Nursery* nursery, unsigned chunkno); + void setCurrentEnd(Nursery* nursery); + void setStartToCurrentPosition(); + bool commitSubChunkRegion(size_t oldCapacity, size_t newCapacity); + void decommitSubChunkRegion(Nursery* nursery, size_t oldCapacity, + size_t newCapacity); + void freeTrailerBlocks(gc::MallocedBlockCache& mallocedBlockCache); + +#ifdef DEBUG + void checkKind(gc::ChunkKind expected) const; + size_t findChunkIndex(uintptr_t chunkAddr) const; +#endif + }; + + Space toSpace; + Space fromSpace; + + gc::GCRuntime* const gc; // The current nursery capacity measured in bytes. It may grow up to this // value without a collection, allocating chunks on demand. This limit may be // changed by maybeResizeNursery() each collection. It includes chunk headers. size_t capacity_; + uintptr_t tenureThreshold_ = 0; + gc::PretenuringNursery pretenuringNursery; mozilla::TimeDuration timeInChunkAlloc_; @@ -553,6 +634,9 @@ class Nursery { mozilla::TimeDuration profileThreshold_; + // Whether to use semispace collection. + bool semispaceEnabled_; + // Whether we will nursery-allocate strings. bool canAllocateStrings_; @@ -595,21 +679,6 @@ class Nursery { bool hasRecentGrowthData; double smoothedTargetSize; - // The set of externally malloced buffers potentially kept live by objects - // stored in the nursery. Any external buffers that do not belong to a - // tenured thing at the end of a minor GC must be freed. - using BufferRelocationOverlay = void*; - using BufferSet = HashSet<void*, PointerHasher<void*>, SystemAllocPolicy>; - BufferSet mallocedBuffers; - size_t mallocedBufferBytes = 0; - - // Wasm "trailer" (C++-heap-allocated) blocks. See comments above on - // ::registerTrailer and ::unregisterTrailer. - Vector<PointerAndUint7, 0, SystemAllocPolicy> trailersAdded_; - Vector<void*, 0, SystemAllocPolicy> trailersRemoved_; - size_t trailersRemovedUsed_ = 0; - size_t trailerBytes_ = 0; - // During a collection most hoisted slot and element buffers indicate their // new location with a forwarding pointer at the base. This does not work // for buffers whose length is less than pointer width, or when different @@ -619,6 +688,8 @@ class Nursery { HashMap<void*, void*, PointerHasher<void*>, SystemAllocPolicy>; ForwardedBufferMap forwardedBuffers; + gc::CellSweepSet cellsToSweep; + // When we assign a unique id to cell in the nursery, that almost always // means that the cell will be in a hash table, and thus, held live, // automatically moving the uid from the nursery to its new home in @@ -629,13 +700,15 @@ class Nursery { // Note: we store the pointers as Cell* here, resulting in an ugly cast in // sweep. This is because this structure is used to help implement // stable object hashing and we have to break the cycle somehow. - using CellsWithUniqueIdVector = Vector<gc::Cell*, 8, SystemAllocPolicy>; + using CellsWithUniqueIdVector = JS::GCVector<gc::Cell*, 8, SystemAllocPolicy>; CellsWithUniqueIdVector cellsWithUid_; // Lists of map and set objects allocated in the nursery or with iterators // allocated there. Such objects need to be swept after minor GC. - Vector<MapObject*, 0, SystemAllocPolicy> mapsWithNurseryMemory_; - Vector<SetObject*, 0, SystemAllocPolicy> setsWithNurseryMemory_; + using MapObjectVector = Vector<MapObject*, 0, SystemAllocPolicy>; + MapObjectVector mapsWithNurseryMemory_; + using SetObjectVector = Vector<SetObject*, 0, SystemAllocPolicy>; + SetObjectVector setsWithNurseryMemory_; UniquePtr<NurseryDecommitTask> decommitTask; @@ -648,11 +721,30 @@ class Nursery { // no correctness impact, only a performance impact. gc::MallocedBlockCache mallocedBlockCache_; + // Whether the previous collection tenured everything. This may be false if + // semispace is in use. + bool tenuredEverything; + friend class gc::GCRuntime; friend class gc::TenuringTracer; friend struct NurseryChunk; }; +MOZ_ALWAYS_INLINE bool Nursery::isInside(const void* p) const { + // TODO: Split this into separate methods. + // TODO: Do we ever need to check both? + return toSpace.isInside(p) || fromSpace.isInside(p); +} + +MOZ_ALWAYS_INLINE bool Nursery::Space::isInside(const void* p) const { + for (auto* chunk : chunks_) { + if (uintptr_t(p) - uintptr_t(chunk) < gc::ChunkSize) { + return true; + } + } + return false; +} + } // namespace js #endif // gc_Nursery_h diff --git a/js/src/gc/NurseryAwareHashMap.h b/js/src/gc/NurseryAwareHashMap.h index 35c2bebcea..4df50c1627 100644 --- a/js/src/gc/NurseryAwareHashMap.h +++ b/js/src/gc/NurseryAwareHashMap.h @@ -11,7 +11,8 @@ #include "gc/Tracer.h" #include "js/GCHashTable.h" #include "js/GCPolicyAPI.h" -#include "js/HashTable.h" +#include "js/GCVector.h" +#include "js/Utility.h" namespace js { @@ -81,7 +82,8 @@ class NurseryAwareHashMap { // Keep a list of all keys for which key->isTenured() is false. This lets us // avoid a full traversal of the map on each minor GC, keeping the minor GC // times proportional to the nursery heap size. - Vector<Key, 0, AllocPolicy> nurseryEntries; + using KeyVector = GCVector<Key, 0, AllocPolicy>; + KeyVector nurseryEntries; public: using Lookup = typename MapType::Lookup; @@ -127,16 +129,16 @@ class NurseryAwareHashMap { } void sweepAfterMinorGC(JSTracer* trc) { - for (auto& key : nurseryEntries) { + nurseryEntries.mutableEraseIf([this, trc](Key& key) { auto p = map.lookup(key); if (!p) { - continue; + return true; } // Drop the entry if the value is not marked. if (!JS::GCPolicy<MapValue>::traceWeak(trc, &p->value())) { map.remove(p); - continue; + return true; } // Update and relocate the key, if the value is still needed. @@ -147,33 +149,65 @@ class NurseryAwareHashMap { // wrappee, as they are just copies. The wrapper map entry is merely used // as a cache to avoid re-copying the string, and currently that entire // cache is flushed on major GC. - MapKey copy(key); - if (!JS::GCPolicy<MapKey>::traceWeak(trc, ©)) { + // + // Since |key| is a reference, this updates the content of the + // nurseryEntries vector. + Key prior = key; + if (!TraceManuallyBarrieredWeakEdge(trc, &key, + "NurseryAwareHashMap key")) { map.remove(p); - continue; + return true; } - if (AllowDuplicates) { + bool valueIsTenured = p->value().unbarrieredGet()->isTenured(); + + if constexpr (AllowDuplicates) { // Drop duplicated keys. // // A key can be forwarded to another place. In this case, rekey the // item. If two or more different keys are forwarded to the same new // key, simply drop the later ones. - if (key == copy) { + if (key == prior) { // No rekey needed. - } else if (map.has(copy)) { + } else if (map.has(key)) { // Key was forwarded to the same place that another key was already // forwarded to. map.remove(p); + return true; } else { - map.rekeyAs(key, copy, copy); + map.rekeyAs(prior, key, key); } } else { - MOZ_ASSERT(key == copy || !map.has(copy)); - map.rekeyIfMoved(key, copy); + MOZ_ASSERT(key == prior || !map.has(key)); + map.rekeyIfMoved(prior, key); + } + + return key->isTenured() && valueIsTenured; + }); + + checkNurseryEntries(); + } + + void checkNurseryEntries() const { +#ifdef DEBUG + AutoEnterOOMUnsafeRegion oomUnsafe; + HashSet<Key, DefaultHasher<Key>, SystemAllocPolicy> set; + for (const auto& key : nurseryEntries) { + if (!set.put(key)) { + oomUnsafe.crash("NurseryAwareHashMap::checkNurseryEntries"); } } - nurseryEntries.clear(); + + for (auto i = map.iter(); !i.done(); i.next()) { + Key key = i.get().key().get(); + MOZ_ASSERT(gc::IsCellPointerValid(key)); + MOZ_ASSERT_IF(IsInsideNursery(key), set.has(key)); + + Value value = i.get().value().unbarrieredGet(); + MOZ_ASSERT(gc::IsCellPointerValid(value)); + MOZ_ASSERT_IF(IsInsideNursery(value), set.has(key)); + } +#endif } void traceWeak(JSTracer* trc) { map.traceWeak(trc); } diff --git a/js/src/gc/Pretenuring.cpp b/js/src/gc/Pretenuring.cpp index a191dbba90..b44bbc901f 100644 --- a/js/src/gc/Pretenuring.cpp +++ b/js/src/gc/Pretenuring.cpp @@ -49,12 +49,12 @@ static constexpr double LowYoungSurvivalThreshold = 0.05; // that must occur before recovery is attempted. static constexpr size_t LowYoungSurvivalCountBeforeRecovery = 2; -// The proportion of the nursery that must be tenured above which a minor +// The proportion of the nursery that must be promoted above which a minor // collection may be determined to have a high nursery survival rate. static constexpr double HighNurserySurvivalPromotionThreshold = 0.6; // The number of nursery allocations made by optimized JIT code that must be -// tenured above which a minor collection may be determined to have a high +// promoted above which a minor collection may be determined to have a high // nursery survival rate. static constexpr size_t HighNurserySurvivalOptimizedAllocThreshold = 10000; @@ -95,7 +95,7 @@ size_t PretenuringNursery::doPretenuring(GCRuntime* gc, JS::GCReason reason, for (ZonesIter zone(gc, SkipAtoms); !zone.done(); zone.next()) { bool highNurserySurvivalRate = promotionRate > HighNurserySurvivalPromotionThreshold && - zone->optimizedAllocSite()->nurseryTenuredCount >= + zone->optimizedAllocSite()->nurseryPromotedCount >= HighNurserySurvivalOptimizedAllocThreshold; zone->pretenuring.noteHighNurserySurvivalRate(highNurserySurvivalRate); if (highNurserySurvivalRate) { @@ -136,6 +136,7 @@ size_t PretenuringNursery::doPretenuring(GCRuntime* gc, JS::GCReason reason, // Catch-all sites don't end up on the list if they are only used from // optimized JIT code, so process them here. + for (ZonesIter zone(gc, SkipAtoms); !zone.done(); zone.next()) { for (auto& site : zone->pretenuring.unknownAllocSites) { updateTotalAllocCounts(&site); @@ -150,6 +151,11 @@ size_t PretenuringNursery::doPretenuring(GCRuntime* gc, JS::GCReason reason, updateTotalAllocCounts(zone->optimizedAllocSite()); zone->optimizedAllocSite()->processCatchAllSite(reportInfo, reportThreshold); + + // The data from the promoted alloc sites is never used so clear them here. + for (AllocSite& site : zone->pretenuring.promotedAllocSites) { + site.resetNurseryAllocations(); + } } if (reportInfo) { @@ -171,7 +177,7 @@ AllocSite::SiteResult AllocSite::processSite(GCRuntime* gc, bool reportInfo, size_t reportThreshold) { MOZ_ASSERT(kind() != Kind::Optimized); - MOZ_ASSERT(nurseryAllocCount >= nurseryTenuredCount); + MOZ_ASSERT(nurseryAllocCount >= nurseryPromotedCount); SiteResult result = NoChange; @@ -180,7 +186,7 @@ AllocSite::SiteResult AllocSite::processSite(GCRuntime* gc, bool wasInvalidated = false; if (nurseryAllocCount > attentionThreshold) { - promotionRate = double(nurseryTenuredCount) / double(nurseryAllocCount); + promotionRate = double(nurseryPromotedCount) / double(nurseryAllocCount); hasPromotionRate = true; AllocSite::State prevState = state(); @@ -402,7 +408,7 @@ bool PretenuringZone::shouldResetPretenuredAllocSites() { /* static */ void AllocSite::printInfoHeader(JS::GCReason reason, double promotionRate) { fprintf(stderr, " %-16s %-16s %-20s %-8s %-8s %-6s %-10s\n", "site", "zone", - "script/kind", "nallocs", "tenures", "prate", "state"); + "script/kind", "nallocs", "promotes", "prate", "state"); } /* static */ @@ -455,8 +461,8 @@ void AllocSite::printInfo(bool hasPromotionRate, double promotionRate, } fprintf(stderr, " %8s", buffer); - // Nursery tenure count. - fprintf(stderr, " %8" PRIu32, nurseryTenuredCount); + // Nursery promotion count. + fprintf(stderr, " %8" PRIu32, nurseryPromotedCount); // Promotion rate, if there were enough allocations. buffer[0] = '\0'; diff --git a/js/src/gc/Pretenuring.h b/js/src/gc/Pretenuring.h index 5aeb5c50d7..93677532e4 100644 --- a/js/src/gc/Pretenuring.h +++ b/js/src/gc/Pretenuring.h @@ -83,7 +83,7 @@ class AllocSite { uint32_t nurseryAllocCount = 0; // Number of nursery allocations that survived. Used during collection. - uint32_t nurseryTenuredCount : 24; + uint32_t nurseryPromotedCount : 24; // Number of times the script has been invalidated. uint32_t invalidationCount : 4; @@ -103,12 +103,12 @@ class AllocSite { uintptr_t rawScript() const { return scriptAndState & ~STATE_MASK; } public: - AllocSite() : nurseryTenuredCount(0), invalidationCount(0), traceKind_(0) {} + AllocSite() : nurseryPromotedCount(0), invalidationCount(0), traceKind_(0) {} // Create a dummy site to use for unknown allocations. explicit AllocSite(JS::Zone* zone, JS::TraceKind kind) : zone_(zone), - nurseryTenuredCount(0), + nurseryPromotedCount(0), invalidationCount(0), traceKind_(uint32_t(kind)) { MOZ_ASSERT(traceKind_ < NurseryTraceKinds); @@ -126,7 +126,7 @@ class AllocSite { void initUnknownSite(JS::Zone* zone, JS::TraceKind kind) { MOZ_ASSERT(!zone_ && scriptAndState == uintptr_t(State::Unknown)); zone_ = zone; - nurseryTenuredCount = 0; + nurseryPromotedCount = 0; invalidationCount = 0; traceKind_ = uint32_t(kind); MOZ_ASSERT(traceKind_ < NurseryTraceKinds); @@ -137,7 +137,7 @@ class AllocSite { MOZ_ASSERT(!zone_ && scriptAndState == uintptr_t(State::Unknown)); zone_ = zone; setScript(WasmScript); - nurseryTenuredCount = 0; + nurseryPromotedCount = 0; invalidationCount = 0; traceKind_ = uint32_t(JS::TraceKind::Object); } @@ -179,24 +179,24 @@ class AllocSite { } bool hasNurseryAllocations() const { - return nurseryAllocCount != 0 || nurseryTenuredCount != 0; + return nurseryAllocCount != 0 || nurseryPromotedCount != 0; } void resetNurseryAllocations() { nurseryAllocCount = 0; - nurseryTenuredCount = 0; + nurseryPromotedCount = 0; } uint32_t incAllocCount() { return ++nurseryAllocCount; } uint32_t* nurseryAllocCountAddress() { return &nurseryAllocCount; } - void incTenuredCount() { + void incPromotedCount() { // The nursery is not large enough for this to overflow. - nurseryTenuredCount++; - MOZ_ASSERT(nurseryTenuredCount != 0); + nurseryPromotedCount++; + MOZ_ASSERT(nurseryPromotedCount != 0); } size_t allocCount() const { - return std::max(nurseryAllocCount, nurseryTenuredCount); + return std::max(nurseryAllocCount, nurseryPromotedCount); } // Called for every active alloc site after minor GC. @@ -259,6 +259,10 @@ class PretenuringZone { // not recorded by optimized JIT code. AllocSite optimizedAllocSite; + // Allocation sites used for nursery cells promoted to the next nursery + // generation that didn't come from optimized alloc sites. + AllocSite promotedAllocSites[NurseryTraceKinds]; + // Count of tenured cell allocations made between each major collection and // how many survived. uint32_t allocCountInNewlyCreatedArenas = 0; @@ -282,6 +286,7 @@ class PretenuringZone { : optimizedAllocSite(zone, JS::TraceKind::Object) { for (uint32_t i = 0; i < NurseryTraceKinds; i++) { unknownAllocSites[i].initUnknownSite(zone, JS::TraceKind(i)); + promotedAllocSites[i].initUnknownSite(zone, JS::TraceKind(i)); } } @@ -291,6 +296,12 @@ class PretenuringZone { return unknownAllocSites[i]; } + AllocSite& promotedAllocSite(JS::TraceKind kind) { + size_t i = size_t(kind); + MOZ_ASSERT(i < NurseryTraceKinds); + return promotedAllocSites[i]; + } + void clearCellCountsInNewlyCreatedArenas() { allocCountInNewlyCreatedArenas = 0; survivorCountInNewlyCreatedArenas = 0; diff --git a/js/src/gc/PublicIterators.h b/js/src/gc/PublicIterators.h index d1072cfe98..7ef6271f63 100644 --- a/js/src/gc/PublicIterators.h +++ b/js/src/gc/PublicIterators.h @@ -35,7 +35,7 @@ class ZonesIter { public: ZonesIter(gc::GCRuntime* gc, ZoneSelector selector) : iterMarker(gc), it(gc->zones().begin()), end(gc->zones().end()) { - if (selector == SkipAtoms) { + if (selector == SkipAtoms && !done()) { MOZ_ASSERT(get()->isAtomsZone()); next(); } diff --git a/js/src/gc/Scheduling.h b/js/src/gc/Scheduling.h index cbaeb1f353..c5ed56dd5f 100644 --- a/js/src/gc/Scheduling.h +++ b/js/src/gc/Scheduling.h @@ -536,6 +536,9 @@ static const bool ParallelMarkingEnabled = false; /* JSGC_INCREMENTAL_WEAKMAP_ENABLED */ static const bool IncrementalWeakMapMarkingEnabled = true; +/* JSGC_SEMISPACE_NURSERY_ENABLED */ +static const bool SemispaceNurseryEnabled = false; + /* JSGC_HELPER_THREAD_RATIO */ static const double HelperThreadRatio = 0.5; diff --git a/js/src/gc/StableCellHasher-inl.h b/js/src/gc/StableCellHasher-inl.h index af0caaad89..34a8827cfb 100644 --- a/js/src/gc/StableCellHasher-inl.h +++ b/js/src/gc/StableCellHasher-inl.h @@ -132,7 +132,6 @@ inline bool HasUniqueId(Cell* cell) { inline void TransferUniqueId(Cell* tgt, Cell* src) { MOZ_ASSERT(src != tgt); - MOZ_ASSERT(!IsInsideNursery(tgt)); MOZ_ASSERT(CurrentThreadCanAccessRuntime(tgt->runtimeFromAnyThread())); MOZ_ASSERT(src->zone() == tgt->zone()); diff --git a/js/src/gc/StoreBuffer-inl.h b/js/src/gc/StoreBuffer-inl.h index 1c97654761..343b953e3a 100644 --- a/js/src/gc/StoreBuffer-inl.h +++ b/js/src/gc/StoreBuffer-inl.h @@ -49,9 +49,10 @@ inline void ArenaCellSet::check() const { MOZ_ASSERT(isEmpty() == !arena); if (!isEmpty()) { MOZ_ASSERT(IsCellPointerValid(arena)); - MOZ_ASSERT(arena->bufferedCells() == this); JSRuntime* runtime = arena->zone->runtimeFromMainThread(); - MOZ_ASSERT(runtime->gc.minorGCCount() == minorGCNumberAtCreation); + uint64_t minorGCCount = runtime->gc.minorGCCount(); + MOZ_ASSERT(minorGCCount == minorGCNumberAtCreation || + minorGCCount == minorGCNumberAtCreation + 1); } #endif } diff --git a/js/src/gc/StoreBuffer.cpp b/js/src/gc/StoreBuffer.cpp index d637eb62b1..1f8023bc62 100644 --- a/js/src/gc/StoreBuffer.cpp +++ b/js/src/gc/StoreBuffer.cpp @@ -20,7 +20,8 @@ void StoreBuffer::checkAccess() const { // The GC runs tasks that may access the storebuffer in parallel and so must // take a lock. The mutator may only access the storebuffer from the main // thread. - if (runtime_->heapState() != JS::HeapState::Idle) { + if (runtime_->heapState() != JS::HeapState::Idle && + runtime_->heapState() != JS::HeapState::MinorCollecting) { MOZ_ASSERT(!CurrentThreadIsGCMarking()); runtime_->gc.assertCurrentThreadHasLockedStoreBuffer(); } else { @@ -30,8 +31,7 @@ void StoreBuffer::checkAccess() const { #endif bool StoreBuffer::WholeCellBuffer::init() { - MOZ_ASSERT(!stringHead_); - MOZ_ASSERT(!nonStringHead_); + MOZ_ASSERT(!head_); if (!storage_) { storage_ = MakeUnique<LifoAlloc>(LifoAllocBlockSize); // This prevents LifoAlloc::Enum from crashing with a release @@ -75,8 +75,7 @@ StoreBuffer::StoreBuffer(JSRuntime* rt) mayHavePointersToDeadCells_(false) #ifdef DEBUG , - mEntered(false), - markingNondeduplicatable(false) + mEntered(false) #endif { } @@ -97,13 +96,11 @@ StoreBuffer::StoreBuffer(StoreBuffer&& other) mayHavePointersToDeadCells_(other.mayHavePointersToDeadCells_) #ifdef DEBUG , - mEntered(other.mEntered), - markingNondeduplicatable(other.markingNondeduplicatable) + mEntered(other.mEntered) #endif { MOZ_ASSERT(enabled_); MOZ_ASSERT(!mEntered); - MOZ_ASSERT(!markingNondeduplicatable); other.disable(); } @@ -213,21 +210,14 @@ ArenaCellSet* StoreBuffer::WholeCellBuffer::allocateCellSet(Arena* arena) { return nullptr; } - // Maintain separate lists for strings and non-strings, so that all buffered - // string whole cells will be processed before anything else (to prevent them - // from being deduplicated when their chars are used by a tenured string.) - bool isString = - MapAllocToTraceKind(arena->getAllocKind()) == JS::TraceKind::String; - AutoEnterOOMUnsafeRegion oomUnsafe; - ArenaCellSet*& head = isString ? stringHead_ : nonStringHead_; - auto* cells = storage_->new_<ArenaCellSet>(arena, head); + auto* cells = storage_->new_<ArenaCellSet>(arena, head_); if (!cells) { oomUnsafe.crash("Failed to allocate ArenaCellSet"); } arena->bufferedCells() = cells; - head = cells; + head_ = cells; if (isAboutToOverflow()) { rt->gc.storeBuffer().setAboutToOverflow( @@ -243,12 +233,10 @@ void gc::CellHeaderPostWriteBarrier(JSObject** ptr, JSObject* prev, } void StoreBuffer::WholeCellBuffer::clear() { - for (auto** headPtr : {&stringHead_, &nonStringHead_}) { - for (auto* set = *headPtr; set; set = set->next) { - set->arena->bufferedCells() = &ArenaCellSet::Empty; - } - *headPtr = nullptr; + for (auto* set = head_; set; set = set->next) { + set->arena->bufferedCells() = &ArenaCellSet::Empty; } + head_ = nullptr; if (storage_) { storage_->used() ? storage_->releaseAll() : storage_->freeAll(); diff --git a/js/src/gc/StoreBuffer.h b/js/src/gc/StoreBuffer.h index 2e117f02c8..0b1ca8af9b 100644 --- a/js/src/gc/StoreBuffer.h +++ b/js/src/gc/StoreBuffer.h @@ -169,8 +169,7 @@ class StoreBuffer { struct WholeCellBuffer { UniquePtr<LifoAlloc> storage_; - ArenaCellSet* stringHead_ = nullptr; - ArenaCellSet* nonStringHead_ = nullptr; + ArenaCellSet* head_ = nullptr; const Cell* last_ = nullptr; WholeCellBuffer() = default; @@ -180,11 +179,9 @@ class StoreBuffer { WholeCellBuffer(WholeCellBuffer&& other) : storage_(std::move(other.storage_)), - stringHead_(other.stringHead_), - nonStringHead_(other.nonStringHead_), + head_(other.head_), last_(other.last_) { - other.stringHead_ = nullptr; - other.nonStringHead_ = nullptr; + other.head_ = nullptr; other.last_ = nullptr; } WholeCellBuffer& operator=(WholeCellBuffer&& other) { @@ -214,13 +211,20 @@ class StoreBuffer { } bool isEmpty() const { - MOZ_ASSERT_IF(!stringHead_ && !nonStringHead_, - !storage_ || storage_->isEmpty()); - return !stringHead_ && !nonStringHead_; + MOZ_ASSERT_IF(!head_, !storage_ || storage_->isEmpty()); + return !head_; } const Cell** lastBufferedPtr() { return &last_; } + CellSweepSet releaseCellSweepSet() { + CellSweepSet set; + std::swap(storage_, set.storage_); + std::swap(head_, set.head_); + last_ = nullptr; + return set; + } + private: ArenaCellSet* allocateCellSet(Arena* arena); }; @@ -339,9 +343,10 @@ class StoreBuffer { bool operator==(const ValueEdge& other) const { return edge == other.edge; } bool operator!=(const ValueEdge& other) const { return edge != other.edge; } + bool isGCThing() const { return edge->isGCThing(); } + Cell* deref() const { - return edge->isGCThing() ? static_cast<Cell*>(edge->toGCThing()) - : nullptr; + return isGCThing() ? static_cast<Cell*>(edge->toGCThing()) : nullptr; } bool maybeInRememberedSet(const Nursery& nursery) const { @@ -449,10 +454,10 @@ class StoreBuffer { return edge != other.edge; } + bool isGCThing() const { return edge->isGCThing(); } + Cell* deref() const { - return edge->isGCThing() ? static_cast<Cell*>(edge->toGCThing()) - : nullptr; - return nullptr; + return isGCThing() ? static_cast<Cell*>(edge->toGCThing()) : nullptr; } bool maybeInRememberedSet(const Nursery& nursery) const { @@ -525,10 +530,6 @@ class StoreBuffer { #endif public: -#ifdef DEBUG - bool markingNondeduplicatable; -#endif - explicit StoreBuffer(JSRuntime* rt); StoreBuffer(const StoreBuffer& other) = delete; @@ -629,6 +630,10 @@ class StoreBuffer { } void traceGenericEntries(JSTracer* trc) { bufferGeneric.trace(trc, this); } + gc::CellSweepSet releaseCellSweepSet() { + return bufferWholeCell.releaseCellSweepSet(); + } + /* For use by our owned buffers and for testing. */ void setAboutToOverflow(JS::GCReason); @@ -639,6 +644,7 @@ class StoreBuffer { }; // A set of cells in an arena used to implement the whole cell store buffer. +// Also used to store a set of cells that need to be swept. class ArenaCellSet { friend class StoreBuffer; @@ -693,7 +699,17 @@ class ArenaCellSet { WordT getWord(size_t wordIndex) const { return bits.getWord(wordIndex); } - void trace(TenuringTracer& mover); + void setWord(size_t wordIndex, WordT value) { + bits.setWord(wordIndex, value); + } + + // Returns the list of ArenaCellSets that need to be swept. + ArenaCellSet* trace(TenuringTracer& mover); + + // At the end of a minor GC, sweep through all tenured dependent strings that + // may point to nursery-allocated chars to update their pointers in case the + // base string moved its chars. + void sweepDependentStrings(); // Sentinel object used for all empty sets. // diff --git a/js/src/gc/Sweeping.cpp b/js/src/gc/Sweeping.cpp index 123b2c9650..2cd6a2c662 100644 --- a/js/src/gc/Sweeping.cpp +++ b/js/src/gc/Sweeping.cpp @@ -441,6 +441,12 @@ void GCRuntime::waitBackgroundSweepEnd() { void GCRuntime::startBackgroundFree() { AutoLockHelperThreadState lock; + + if (lifoBlocksToFree.ref().isEmpty() && + buffersToFreeAfterMinorGC.ref().empty()) { + return; + } + freeTask.startOrRunIfIdle(lock); } @@ -1194,18 +1200,19 @@ class ImmediateSweepWeakCacheTask : public GCParallelTask { }; void GCRuntime::updateAtomsBitmap() { - DenseBitmap marked; - if (atomMarking.computeBitmapFromChunkMarkBits(rt, marked)) { - for (GCZonesIter zone(this); !zone.done(); zone.next()) { - atomMarking.refineZoneBitmapForCollectedZone(zone, marked); + size_t collectedZones = 0; + size_t uncollectedZones = 0; + for (ZonesIter zone(this, SkipAtoms); !zone.done(); zone.next()) { + if (zone->isCollecting()) { + collectedZones++; + } else { + uncollectedZones++; } - } else { - // Ignore OOM in computeBitmapFromChunkMarkBits. The - // refineZoneBitmapForCollectedZone call can only remove atoms from the - // zone bitmap, so it is conservative to just not call it. } - atomMarking.markAtomsUsedByUncollectedZones(rt); + atomMarking.refineZoneBitmapsForCollectedZones(this, collectedZones); + + atomMarking.markAtomsUsedByUncollectedZones(this, uncollectedZones); // For convenience sweep these tables non-incrementally as part of bitmap // sweeping; they are likely to be much smaller than the main atoms table. diff --git a/js/src/gc/Tenuring.cpp b/js/src/gc/Tenuring.cpp index a9506cfa14..d38a374599 100644 --- a/js/src/gc/Tenuring.cpp +++ b/js/src/gc/Tenuring.cpp @@ -18,6 +18,7 @@ #include "gc/Pretenuring.h" #include "gc/Zone.h" #include "jit/JitCode.h" +#include "js/TypeDecls.h" #include "proxy/Proxy.h" #include "vm/BigIntType.h" #include "vm/JSScript.h" @@ -44,104 +45,120 @@ using mozilla::PodCopy; constexpr size_t MAX_DEDUPLICATABLE_STRING_LENGTH = 500; -TenuringTracer::TenuringTracer(JSRuntime* rt, Nursery* nursery) +TenuringTracer::TenuringTracer(JSRuntime* rt, Nursery* nursery, + bool tenureEverything) : JSTracer(rt, JS::TracerKind::Tenuring, JS::WeakMapTraceAction::TraceKeysAndValues), - nursery_(*nursery) { + nursery_(*nursery), + tenureEverything(tenureEverything) { stringDeDupSet.emplace(); } -size_t TenuringTracer::getTenuredSize() const { - return tenuredSize + tenuredCells * sizeof(NurseryCellHeader); +size_t TenuringTracer::getPromotedSize() const { + return promotedSize + promotedCells * sizeof(NurseryCellHeader); } -size_t TenuringTracer::getTenuredCells() const { return tenuredCells; } - -static inline void UpdateAllocSiteOnTenure(Cell* cell) { - AllocSite* site = NurseryCellHeader::from(cell)->allocSite(); - site->incTenuredCount(); -} +size_t TenuringTracer::getPromotedCells() const { return promotedCells; } void TenuringTracer::onObjectEdge(JSObject** objp, const char* name) { JSObject* obj = *objp; - if (!IsInsideNursery(obj)) { + if (!nursery_.inCollectedRegion(obj)) { + MOZ_ASSERT(!obj->isForwarded()); return; } + *objp = promoteOrForward(obj); + MOZ_ASSERT(!(*objp)->isForwarded()); +} + +JSObject* TenuringTracer::promoteOrForward(JSObject* obj) { + MOZ_ASSERT(nursery_.inCollectedRegion(obj)); + if (obj->isForwarded()) { const gc::RelocationOverlay* overlay = gc::RelocationOverlay::fromCell(obj); - *objp = static_cast<JSObject*>(overlay->forwardingAddress()); - return; + obj = static_cast<JSObject*>(overlay->forwardingAddress()); + if (IsInsideNursery(obj)) { + promotedToNursery = true; + } + return obj; } - onNonForwardedNurseryObjectEdge(objp); + return onNonForwardedNurseryObject(obj); } -void TenuringTracer::onNonForwardedNurseryObjectEdge(JSObject** objp) { - JSObject* obj = *objp; +JSObject* TenuringTracer::onNonForwardedNurseryObject(JSObject* obj) { MOZ_ASSERT(IsInsideNursery(obj)); MOZ_ASSERT(!obj->isForwarded()); - UpdateAllocSiteOnTenure(obj); - - // Take a fast path for tenuring a plain object which is by far the most + // Take a fast path for promoting a plain object as this is by far the most // common case. if (obj->is<PlainObject>()) { - *objp = movePlainObjectToTenured(&obj->as<PlainObject>()); - return; + return promotePlainObject(&obj->as<PlainObject>()); } - *objp = moveToTenuredSlow(obj); + return promoteObjectSlow(obj); } void TenuringTracer::onStringEdge(JSString** strp, const char* name) { JSString* str = *strp; - if (!IsInsideNursery(str)) { + if (!nursery_.inCollectedRegion(str)) { return; } + *strp = promoteOrForward(str); +} + +JSString* TenuringTracer::promoteOrForward(JSString* str) { + MOZ_ASSERT(nursery_.inCollectedRegion(str)); + if (str->isForwarded()) { const gc::RelocationOverlay* overlay = gc::RelocationOverlay::fromCell(str); - *strp = static_cast<JSString*>(overlay->forwardingAddress()); - return; + str = static_cast<JSString*>(overlay->forwardingAddress()); + if (IsInsideNursery(str)) { + promotedToNursery = true; + } + return str; } - onNonForwardedNurseryStringEdge(strp); + return onNonForwardedNurseryString(str); } -void TenuringTracer::onNonForwardedNurseryStringEdge(JSString** strp) { - JSString* str = *strp; +JSString* TenuringTracer::onNonForwardedNurseryString(JSString* str) { MOZ_ASSERT(IsInsideNursery(str)); MOZ_ASSERT(!str->isForwarded()); - UpdateAllocSiteOnTenure(str); - - *strp = moveToTenured(str); + return promoteString(str); } void TenuringTracer::onBigIntEdge(JS::BigInt** bip, const char* name) { JS::BigInt* bi = *bip; - if (!IsInsideNursery(bi)) { + if (!nursery_.inCollectedRegion(bi)) { return; } + *bip = promoteOrForward(bi); +} + +JS::BigInt* TenuringTracer::promoteOrForward(JS::BigInt* bi) { + MOZ_ASSERT(nursery_.inCollectedRegion(bi)); + if (bi->isForwarded()) { const gc::RelocationOverlay* overlay = gc::RelocationOverlay::fromCell(bi); - *bip = static_cast<JS::BigInt*>(overlay->forwardingAddress()); - return; + bi = static_cast<JS::BigInt*>(overlay->forwardingAddress()); + if (IsInsideNursery(bi)) { + promotedToNursery = true; + } + return bi; } - onNonForwardedNurseryBigIntEdge(bip); + return onNonForwardedNurseryBigInt(bi); } -void TenuringTracer::onNonForwardedNurseryBigIntEdge(JS::BigInt** bip) { - JS::BigInt* bi = *bip; +JS::BigInt* TenuringTracer::onNonForwardedNurseryBigInt(JS::BigInt* bi) { MOZ_ASSERT(IsInsideNursery(bi)); MOZ_ASSERT(!bi->isForwarded()); - UpdateAllocSiteOnTenure(bi); - - *bip = moveToTenured(bi); + return promoteBigInt(bi); } void TenuringTracer::onSymbolEdge(JS::Symbol** symp, const char* name) {} @@ -156,7 +173,7 @@ void TenuringTracer::onJitCodeEdge(jit::JitCode** codep, const char* name) {} void TenuringTracer::onScopeEdge(Scope** scopep, const char* name) {} void TenuringTracer::traverse(JS::Value* thingp) { - MOZ_ASSERT(!nursery().isInside(thingp)); + MOZ_ASSERT(!nursery().inCollectedRegion(thingp)); Value value = *thingp; CheckTracedThing(this, value); @@ -166,66 +183,71 @@ void TenuringTracer::traverse(JS::Value* thingp) { } Cell* cell = value.toGCThing(); - if (!IsInsideNursery(cell)) { + if (!nursery_.inCollectedRegion(cell)) { return; } if (cell->isForwarded()) { const gc::RelocationOverlay* overlay = gc::RelocationOverlay::fromCell(cell); - thingp->changeGCThingPayload(overlay->forwardingAddress()); + Cell* target = overlay->forwardingAddress(); + thingp->changeGCThingPayload(target); + if (IsInsideNursery(target)) { + promotedToNursery = true; + } return; } // We only care about a few kinds of GC thing here and this generates much // tighter code than using MapGCThingTyped. if (value.isObject()) { - JSObject* obj = &value.toObject(); - onNonForwardedNurseryObjectEdge(&obj); + JSObject* obj = onNonForwardedNurseryObject(&value.toObject()); MOZ_ASSERT(obj != &value.toObject()); *thingp = JS::ObjectValue(*obj); return; } #ifdef ENABLE_RECORD_TUPLE if (value.isExtendedPrimitive()) { - JSObject* obj = &value.toExtendedPrimitive(); - onNonForwardedNurseryObjectEdge(&obj); + JSObject* obj = onNonForwardedNurseryObject(&value.toExtendedPrimitive()); MOZ_ASSERT(obj != &value.toExtendedPrimitive()); *thingp = JS::ExtendedPrimitiveValue(*obj); return; } #endif if (value.isString()) { - JSString* str = value.toString(); - onNonForwardedNurseryStringEdge(&str); + JSString* str = onNonForwardedNurseryString(value.toString()); MOZ_ASSERT(str != value.toString()); *thingp = JS::StringValue(str); return; } MOZ_ASSERT(value.isBigInt()); - JS::BigInt* bi = value.toBigInt(); - onNonForwardedNurseryBigIntEdge(&bi); + JS::BigInt* bi = onNonForwardedNurseryBigInt(value.toBigInt()); MOZ_ASSERT(bi != value.toBigInt()); *thingp = JS::BigIntValue(bi); } void TenuringTracer::traverse(wasm::AnyRef* thingp) { - MOZ_ASSERT(!nursery().isInside(thingp)); + MOZ_ASSERT(!nursery().inCollectedRegion(thingp)); wasm::AnyRef value = *thingp; CheckTracedThing(this, value); + Cell* cell = value.toGCThing(); + if (!nursery_.inCollectedRegion(cell)) { + return; + } + wasm::AnyRef post = wasm::AnyRef::invalid(); switch (value.kind()) { case wasm::AnyRefKind::Object: { - JSObject* obj = &value.toJSObject(); - onObjectEdge(&obj, "value"); + JSObject* obj = promoteOrForward(&value.toJSObject()); + MOZ_ASSERT(obj != &value.toJSObject()); post = wasm::AnyRef::fromJSObject(*obj); break; } case wasm::AnyRefKind::String: { - JSString* str = value.toJSString(); - onStringEdge(&str, "string"); + JSString* str = promoteOrForward(value.toJSString()); + MOZ_ASSERT(str != value.toJSString()); post = wasm::AnyRef::fromJSString(str); break; } @@ -236,11 +258,20 @@ void TenuringTracer::traverse(wasm::AnyRef* thingp) { } } - if (post != value) { - *thingp = post; - } + *thingp = post; } +class MOZ_RAII TenuringTracer::AutoPromotedAnyToNursery { + public: + explicit AutoPromotedAnyToNursery(TenuringTracer& trc) : trc_(trc) { + trc.promotedToNursery = false; + } + explicit operator bool() const { return trc_.promotedToNursery; } + + private: + TenuringTracer& trc_; +}; + template <typename T> void js::gc::StoreBuffer::MonoTypeBuffer<T>::trace(TenuringTracer& mover, StoreBuffer* owner) { @@ -279,6 +310,8 @@ void js::gc::StoreBuffer::SlotsEdge::trace(TenuringTracer& mover) const { MOZ_ASSERT(!IsInsideNursery(obj), "obj shouldn't live in nursery."); + TenuringTracer::AutoPromotedAnyToNursery promotedToNursery(mover); + if (kind() == ElementKind) { uint32_t initLen = obj->getDenseInitializedLength(); uint32_t numShifted = obj->getElementsHeader()->numShiftedElements(); @@ -289,99 +322,60 @@ void js::gc::StoreBuffer::SlotsEdge::trace(TenuringTracer& mover) const { clampedEnd = numShifted < clampedEnd ? clampedEnd - numShifted : 0; clampedEnd = std::min(clampedEnd, initLen); MOZ_ASSERT(clampedStart <= clampedEnd); - mover.traceSlots( - static_cast<HeapSlot*>(obj->getDenseElements() + clampedStart) - ->unbarrieredAddress(), - clampedEnd - clampedStart); + auto* slotStart = + static_cast<HeapSlot*>(obj->getDenseElements() + clampedStart); + uint32_t nslots = clampedEnd - clampedStart; + mover.traceObjectElements(slotStart->unbarrieredAddress(), nslots); } else { uint32_t start = std::min(start_, obj->slotSpan()); uint32_t end = std::min(start_ + count_, obj->slotSpan()); MOZ_ASSERT(start <= end); mover.traceObjectSlots(obj, start, end); } + + if (promotedToNursery) { + mover.runtime()->gc.storeBuffer().putSlot(obj, kind(), start_, count_); + } } static inline void TraceWholeCell(TenuringTracer& mover, JSObject* object) { - MOZ_ASSERT_IF(object->storeBuffer(), - !object->storeBuffer()->markingNondeduplicatable); mover.traceObject(object); } -// Non-deduplicatable marking is necessary because of the following 2 reasons: +// Return whether the string needs to be swept. // -// 1. Tenured string chars cannot be updated: +// We can break down the relevant dependency chains as follows: // -// If any of the tenured string's bases were deduplicated during tenuring, -// the tenured string's chars pointer would need to be adjusted. This would -// then require updating any other tenured strings that are dependent on the -// first tenured string, and we have no way to find them without scanning -// the entire tenured heap. +// T -> T2 : will not be swept, but safe because T2.chars is fixed. +// T -> N1 -> ... -> T2 : safe because T2.chars is fixed +// T -> N1 -> ... -> N2 : update T.chars += tenured(N2).chars - N2.chars // -// 2. Tenured string cannot store its nursery base or base's chars: +// Collapse the base chain down to simply T -> T2 or T -> N2. The pointer update +// will happen during sweeping. // -// Tenured strings have no place to stash a pointer to their nursery base or -// its chars. You need to be able to traverse any dependent string's chain -// of bases up to a nursery "root base" that points to the malloced chars -// that the dependent strings started out pointing to, so that you can -// calculate the offset of any dependent string and update the ptr+offset if -// the root base gets deduplicated to a different allocation. Tenured -// strings in this base chain will stop you from reaching the nursery -// version of the root base; you can only get to the tenured version, and it -// has no place to store the original chars pointer. -static inline void PreventDeduplicationOfReachableStrings(JSString* str) { - MOZ_ASSERT(str->isTenured()); - MOZ_ASSERT(!str->isForwarded()); - - JSLinearString* baseOrRelocOverlay = str->nurseryBaseOrRelocOverlay(); - - // Walk along the chain of dependent strings' base string pointers - // to mark them all non-deduplicatable. - while (true) { - // baseOrRelocOverlay can be one of the three cases: - // 1. forwarded nursery string: - // The forwarded string still retains the flag that can tell whether - // this string is a dependent string with a base. Its - // StringRelocationOverlay holds a saved pointer to its base in the - // nursery. - // 2. not yet forwarded nursery string: - // Retrieve the base field directly from the string. - // 3. tenured string: - // The nursery base chain ends here, so stop traversing. - if (baseOrRelocOverlay->isForwarded()) { - JSLinearString* tenuredBase = Forwarded(baseOrRelocOverlay); - if (!tenuredBase->hasBase()) { - break; - } - baseOrRelocOverlay = StringRelocationOverlay::fromCell(baseOrRelocOverlay) - ->savedNurseryBaseOrRelocOverlay(); - } else { - JSLinearString* base = baseOrRelocOverlay; - if (base->isTenured()) { - break; - } - if (base->isDeduplicatable()) { - base->setNonDeduplicatable(); - } - if (!base->hasBase()) { - break; - } - baseOrRelocOverlay = base->nurseryBaseOrRelocOverlay(); - } - } -} - -static inline void TraceWholeCell(TenuringTracer& mover, JSString* str) { - MOZ_ASSERT_IF(str->storeBuffer(), - str->storeBuffer()->markingNondeduplicatable); - - // Mark all strings reachable from the tenured string `str` as - // non-deduplicatable. These strings are the bases of the tenured dependent - // string. +// Note that in cases like T -> N1 -> T2 -> T3 -> N2, both T -> N1 and T3 -> N2 +// will be processed by the whole cell buffer (or rather, only T and T3 will +// be in the store buffer). The order that these strings are +// visited does not matter because the nursery bases are left alone until +// sweeping. +static inline bool TraceWholeCell(TenuringTracer& mover, JSString* str) { if (str->hasBase()) { - PreventDeduplicationOfReachableStrings(str); + // For tenured dependent strings -> nursery string edges, sweep the + // (tenured) strings at the end of nursery marking to update chars pointers + // that were in the nursery. Rather than updating the base pointer to point + // directly to the tenured version of itself, we will leave it pointing at + // the nursery Cell (which will become a StringRelocationOverlay during the + // minor GC.) + JSLinearString* base = str->nurseryBaseOrRelocOverlay(); + if (IsInsideNursery(base)) { + str->traceBaseFromStoreBuffer(&mover); + return IsInsideNursery(str->nurseryBaseOrRelocOverlay()); + } } str->traceChildren(&mover); + + return false; } static inline void TraceWholeCell(TenuringTracer& mover, BaseScript* script) { @@ -394,70 +388,173 @@ static inline void TraceWholeCell(TenuringTracer& mover, } template <typename T> -static void TraceBufferedCells(TenuringTracer& mover, Arena* arena, - ArenaCellSet* cells) { +bool TenuringTracer::traceBufferedCells(Arena* arena, ArenaCellSet* cells) { for (size_t i = 0; i < MaxArenaCellIndex; i += cells->BitsPerWord) { ArenaCellSet::WordT bitset = cells->getWord(i / cells->BitsPerWord); while (bitset) { size_t bit = i + js::detail::CountTrailingZeroes(bitset); + bitset &= bitset - 1; // Clear the low bit. + auto cell = reinterpret_cast<T*>(uintptr_t(arena) + ArenaCellIndexBytes * bit); - TraceWholeCell(mover, cell); - bitset &= bitset - 1; // Clear the low bit. + + TenuringTracer::AutoPromotedAnyToNursery promotedToNursery(*this); + + TraceWholeCell(*this, cell); + + if (promotedToNursery) { + runtime()->gc.storeBuffer().putWholeCell(cell); + } } } + + return false; } -void ArenaCellSet::trace(TenuringTracer& mover) { - for (ArenaCellSet* cells = this; cells; cells = cells->next) { +template <> +bool TenuringTracer::traceBufferedCells<JSString>(Arena* arena, + ArenaCellSet* cells) { + bool needsSweep = false; + for (size_t i = 0; i < MaxArenaCellIndex; i += cells->BitsPerWord) { + ArenaCellSet::WordT bitset = cells->getWord(i / cells->BitsPerWord); + ArenaCellSet::WordT tosweep = bitset; + while (bitset) { + size_t bit = i + js::detail::CountTrailingZeroes(bitset); + auto* cell = reinterpret_cast<JSString*>(uintptr_t(arena) + + ArenaCellIndexBytes * bit); + TenuringTracer::AutoPromotedAnyToNursery promotedToNursery(*this); + bool needsSweep = TraceWholeCell(*this, cell); + if (promotedToNursery) { + runtime()->gc.storeBuffer().putWholeCell(cell); + } + ArenaCellSet::WordT mask = bitset - 1; + bitset &= mask; + if (!needsSweep) { + tosweep &= mask; + } + } + + cells->setWord(i / cells->BitsPerWord, tosweep); + if (tosweep) { + needsSweep = true; + } + } + + return needsSweep; +} + +ArenaCellSet* ArenaCellSet::trace(TenuringTracer& mover) { + ArenaCellSet* head = nullptr; + + ArenaCellSet* cells = this; + while (cells) { cells->check(); Arena* arena = cells->arena; arena->bufferedCells() = &ArenaCellSet::Empty; JS::TraceKind kind = MapAllocToTraceKind(arena->getAllocKind()); + bool needsSweep; switch (kind) { case JS::TraceKind::Object: - TraceBufferedCells<JSObject>(mover, arena, cells); + needsSweep = mover.traceBufferedCells<JSObject>(arena, cells); break; case JS::TraceKind::String: - TraceBufferedCells<JSString>(mover, arena, cells); + needsSweep = mover.traceBufferedCells<JSString>(arena, cells); break; case JS::TraceKind::Script: - TraceBufferedCells<BaseScript>(mover, arena, cells); + needsSweep = mover.traceBufferedCells<BaseScript>(arena, cells); break; case JS::TraceKind::JitCode: - TraceBufferedCells<jit::JitCode>(mover, arena, cells); + needsSweep = mover.traceBufferedCells<jit::JitCode>(arena, cells); break; default: MOZ_CRASH("Unexpected trace kind"); } + + ArenaCellSet* next = cells->next; + if (needsSweep) { + cells->next = head; + head = cells; + } + + cells = next; } + + return head; } void js::gc::StoreBuffer::WholeCellBuffer::trace(TenuringTracer& mover, StoreBuffer* owner) { MOZ_ASSERT(owner->isEnabled()); -#ifdef DEBUG - // Verify that all string whole cells are traced first before any other - // strings are visited for any reason. - MOZ_ASSERT(!owner->markingNondeduplicatable); - owner->markingNondeduplicatable = true; -#endif - // Trace all of the strings to mark the non-deduplicatable bits, then trace - // all other whole cells. - if (stringHead_) { - stringHead_->trace(mover); + if (head_) { + head_ = head_->trace(mover); } -#ifdef DEBUG - owner->markingNondeduplicatable = false; -#endif - if (nonStringHead_) { - nonStringHead_->trace(mover); +} + +// Sweep a tenured dependent string with a nursery base. The base chain will +// have been collapsed to a single link before this string was added to the +// sweep set, so only the simple case of a tenured dependent string with a +// nursery base needs to be considered. +template <typename CharT> +void JSDependentString::sweepTypedAfterMinorGC() { + MOZ_ASSERT(isTenured()); + MOZ_ASSERT(IsInsideNursery(nurseryBaseOrRelocOverlay())); + + JSLinearString* base = nurseryBaseOrRelocOverlay(); + MOZ_ASSERT(IsInsideNursery(base)); + MOZ_ASSERT(!Forwarded(base)->hasBase(), "base chain should be collapsed"); + MOZ_ASSERT(base->isForwarded(), "root base should be kept alive"); + auto* baseOverlay = js::gc::StringRelocationOverlay::fromCell(base); + const CharT* oldBaseChars = baseOverlay->savedNurseryChars<CharT>(); + + // We have the base's original chars pointer and its current chars pointer. + // Update our chars pointer, which is an offset from the original base + // chars, and make it point to the same offset within the root's chars. + // (Most of the time, the base chars didn't move and so this has no + // effect.) + const CharT* oldChars = JSString::nonInlineCharsRaw<CharT>(); + size_t offset = oldChars - oldBaseChars; + JSLinearString* tenuredBase = Forwarded(base); + MOZ_ASSERT(offset < tenuredBase->length()); + + const CharT* newBaseChars = tenuredBase->JSString::nonInlineCharsRaw<CharT>(); + relocateNonInlineChars(newBaseChars, offset); + + d.s.u3.base = tenuredBase; +} + +inline void JSDependentString::sweepAfterMinorGC() { + if (hasTwoByteChars()) { + sweepTypedAfterMinorGC<char16_t>(); + } else { + sweepTypedAfterMinorGC<JS::Latin1Char>(); + } +} + +static void SweepDependentStrings(Arena* arena, ArenaCellSet* cells) { + for (size_t i = 0; i < MaxArenaCellIndex; i += cells->BitsPerWord) { + ArenaCellSet::WordT bitset = cells->getWord(i / cells->BitsPerWord); + while (bitset) { + size_t bit = i + js::detail::CountTrailingZeroes(bitset); + auto* str = reinterpret_cast<JSString*>(uintptr_t(arena) + + ArenaCellIndexBytes * bit); + MOZ_ASSERT(str->isTenured()); + str->asDependent().sweepAfterMinorGC(); + bitset &= bitset - 1; // Clear the low bit. + } } +} - stringHead_ = nonStringHead_ = nullptr; +void ArenaCellSet::sweepDependentStrings() { + for (ArenaCellSet* cells = this; cells; cells = cells->next) { + Arena* arena = cells->arena; + arena->bufferedCells() = &ArenaCellSet::Empty; + MOZ_ASSERT(MapAllocToTraceKind(arena->getAllocKind()) == + JS::TraceKind::String); + SweepDependentStrings(arena, cells); + } } template <typename T> @@ -481,18 +578,42 @@ void js::gc::StoreBuffer::CellPtrEdge<T>::trace(TenuringTracer& mover) const { edge, JS::TraceKind::String)); } - DispatchToOnEdge(&mover, edge, "CellPtrEdge"); + if (!mover.nursery().inCollectedRegion(thing)) { + return; + } + + *edge = mover.promoteOrForward(thing); + + if (IsInsideNursery(*edge)) { + mover.runtime()->gc.storeBuffer().putCell(edge); + } } void js::gc::StoreBuffer::ValueEdge::trace(TenuringTracer& mover) const { - if (deref()) { - mover.traverse(edge); + if (!isGCThing()) { + return; + } + + TenuringTracer::AutoPromotedAnyToNursery promotedToNursery(mover); + + mover.traverse(edge); + + if (promotedToNursery) { + mover.runtime()->gc.storeBuffer().putValue(edge); } } void js::gc::StoreBuffer::WasmAnyRefEdge::trace(TenuringTracer& mover) const { - if (deref()) { - mover.traverse(edge); + if (!isGCThing()) { + return; + } + + TenuringTracer::AutoPromotedAnyToNursery promotedToNursery(mover); + + mover.traverse(edge); + + if (promotedToNursery) { + mover.runtime()->gc.storeBuffer().putWasmAnyRef(edge); } } @@ -513,7 +634,7 @@ void js::gc::TenuringTracer::traceObject(JSObject* obj) { if (!nobj->hasEmptyElements()) { HeapSlotArray elements = nobj->getDenseElements(); Value* elems = elements.begin()->unbarrieredAddress(); - traceSlots(elems, elems + nobj->getDenseInitializedLength()); + traceObjectElements(elems, nobj->getDenseInitializedLength()); } traceObjectSlots(nobj, 0, nobj->slotSpan()); @@ -527,16 +648,17 @@ void js::gc::TenuringTracer::traceObjectSlots(NativeObject* nobj, nobj->forEachSlotRange(start, end, traceRange); } +void js::gc::TenuringTracer::traceObjectElements(JS::Value* vp, + uint32_t count) { + traceSlots(vp, vp + count); +} + void js::gc::TenuringTracer::traceSlots(Value* vp, Value* end) { for (; vp != end; ++vp) { traverse(vp); } } -inline void js::gc::TenuringTracer::traceSlots(JS::Value* vp, uint32_t nslots) { - traceSlots(vp, vp + nslots); -} - void js::gc::TenuringTracer::traceString(JSString* str) { str->traceChildren(this); } @@ -564,25 +686,73 @@ inline void js::gc::TenuringTracer::insertIntoObjectFixupList( } template <typename T> -inline T* js::gc::TenuringTracer::allocTenured(Zone* zone, AllocKind kind) { - return static_cast<T*>(static_cast<Cell*>(AllocateCellInGC(zone, kind))); +inline T* js::gc::TenuringTracer::alloc(Zone* zone, AllocKind kind, Cell* src) { + AllocSite* site = NurseryCellHeader::from(src)->allocSite(); + site->incPromotedCount(); + + void* ptr = allocCell<T::TraceKind>(zone, kind, site, src); + auto* cell = reinterpret_cast<T*>(ptr); + if (IsInsideNursery(cell)) { + MOZ_ASSERT(!nursery().inCollectedRegion(cell)); + promotedToNursery = true; + } + + return cell; } -JSString* js::gc::TenuringTracer::allocTenuredString(JSString* src, Zone* zone, - AllocKind dstKind) { - JSString* dst = allocTenured<JSString>(zone, dstKind); - tenuredSize += moveStringToTenured(dst, src, dstKind); - tenuredCells++; +template <JS::TraceKind traceKind> +void* js::gc::TenuringTracer::allocCell(Zone* zone, AllocKind allocKind, + AllocSite* site, Cell* src) { + MOZ_ASSERT(zone == src->zone()); + + if (!shouldTenure(zone, traceKind, src)) { + // Allocations from the optimized alloc site continue to use that site, + // otherwise a special promoted alloc site it used. + if (site->kind() != AllocSite::Kind::Optimized) { + site = &zone->pretenuring.promotedAllocSite(traceKind); + } + + size_t thingSize = Arena::thingSize(allocKind); + void* ptr = nursery_.tryAllocateCell(site, thingSize, traceKind); + if (MOZ_LIKELY(ptr)) { + return ptr; + } + + JSContext* cx = runtime()->mainContextFromOwnThread(); + ptr = CellAllocator::RetryNurseryAlloc<NoGC>(cx, traceKind, allocKind, + thingSize, site); + if (MOZ_LIKELY(ptr)) { + return ptr; + } + + // The nursery is full. This is unlikely but can happen. Fall through to + // the tenured allocation path. + } + + return AllocateTenuredCellInGC(zone, allocKind); +} + +JSString* js::gc::TenuringTracer::allocString(JSString* src, Zone* zone, + AllocKind dstKind) { + JSString* dst = alloc<JSString>(zone, dstKind, src); + promotedSize += moveString(dst, src, dstKind); + promotedCells++; return dst; } -JSObject* js::gc::TenuringTracer::moveToTenuredSlow(JSObject* src) { +bool js::gc::TenuringTracer::shouldTenure(Zone* zone, JS::TraceKind traceKind, + Cell* cell) { + return tenureEverything || !zone->allocKindInNursery(traceKind) || + nursery_.shouldTenure(cell); +} + +JSObject* js::gc::TenuringTracer::promoteObjectSlow(JSObject* src) { MOZ_ASSERT(IsInsideNursery(src)); MOZ_ASSERT(!src->is<PlainObject>()); AllocKind dstKind = src->allocKindForTenure(nursery()); - auto* dst = allocTenured<JSObject>(src->nurseryZone(), dstKind); + auto* dst = alloc<JSObject>(src->nurseryZone(), dstKind, src); size_t srcSize = Arena::thingSize(dstKind); @@ -590,8 +760,8 @@ JSObject* js::gc::TenuringTracer::moveToTenuredSlow(JSObject* src) { // and dst. We deal with this by copying elements manually, possibly // re-inlining them if there is adequate room inline in dst. // - // For Arrays and Tuples we're reducing tenuredSize to the smaller srcSize - // because moveElementsToTenured() accounts for all Array or Tuple elements, + // For Arrays and Tuples we're reducing promotedSize to the smaller srcSize + // because moveElements() accounts for all Array or Tuple elements, // even if they are inlined. if (src->is<FixedLengthTypedArrayObject>()) { auto* tarray = &src->as<FixedLengthTypedArrayObject>(); @@ -613,8 +783,8 @@ JSObject* js::gc::TenuringTracer::moveToTenuredSlow(JSObject* src) { srcSize = sizeof(NativeObject); } - tenuredSize += srcSize; - tenuredCells++; + promotedSize += srcSize; + promotedCells++; // Copy the Cell contents. MOZ_ASSERT(OffsetFromChunkStart(src) >= sizeof(ChunkBase)); @@ -625,8 +795,8 @@ JSObject* js::gc::TenuringTracer::moveToTenuredSlow(JSObject* src) { if (src->is<NativeObject>()) { NativeObject* ndst = &dst->as<NativeObject>(); NativeObject* nsrc = &src->as<NativeObject>(); - tenuredSize += moveSlotsToTenured(ndst, nsrc); - tenuredSize += moveElementsToTenured(ndst, nsrc, dstKind); + promotedSize += moveSlots(ndst, nsrc); + promotedSize += moveElements(ndst, nsrc, dstKind); } JSObjectMovedOp op = dst->getClass()->extObjectMovedOp(); @@ -634,7 +804,7 @@ JSObject* js::gc::TenuringTracer::moveToTenuredSlow(JSObject* src) { if (op) { // Tell the hazard analysis that the object moved hook can't GC. JS::AutoSuppressGCAnalysis nogc; - tenuredSize += op(dst, src); + promotedSize += op(dst, src); } else { MOZ_ASSERT_IF(src->getClass()->hasFinalize(), CanNurseryAllocateFinalizedClass(src->getClass())); @@ -647,18 +817,17 @@ JSObject* js::gc::TenuringTracer::moveToTenuredSlow(JSObject* src) { return dst; } -inline JSObject* js::gc::TenuringTracer::movePlainObjectToTenured( - PlainObject* src) { - // Fast path version of moveToTenuredSlow() for specialized for PlainObject. +inline JSObject* js::gc::TenuringTracer::promotePlainObject(PlainObject* src) { + // Fast path version of promoteObjectSlow() for specialized for PlainObject. MOZ_ASSERT(IsInsideNursery(src)); AllocKind dstKind = src->allocKindForTenure(); - auto* dst = allocTenured<PlainObject>(src->nurseryZone(), dstKind); + auto* dst = alloc<PlainObject>(src->nurseryZone(), dstKind, src); size_t srcSize = Arena::thingSize(dstKind); - tenuredSize += srcSize; - tenuredCells++; + promotedSize += srcSize; + promotedCells++; // Copy the Cell contents. MOZ_ASSERT(OffsetFromChunkStart(src) >= sizeof(ChunkBase)); @@ -666,8 +835,8 @@ inline JSObject* js::gc::TenuringTracer::movePlainObjectToTenured( js_memcpy(dst, src, srcSize); // Move the slots and elements. - tenuredSize += moveSlotsToTenured(dst, src); - tenuredSize += moveElementsToTenured(dst, src, dstKind); + promotedSize += moveSlots(dst, src); + promotedSize += moveElements(dst, src, dstKind); MOZ_ASSERT(!dst->getClass()->extObjectMovedOp()); @@ -678,8 +847,7 @@ inline JSObject* js::gc::TenuringTracer::movePlainObjectToTenured( return dst; } -size_t js::gc::TenuringTracer::moveSlotsToTenured(NativeObject* dst, - NativeObject* src) { +size_t js::gc::TenuringTracer::moveSlots(NativeObject* dst, NativeObject* src) { /* Fixed slots have already been copied over. */ if (!src->hasDynamicSlots()) { return 0; @@ -702,9 +870,9 @@ size_t js::gc::TenuringTracer::moveSlotsToTenured(NativeObject* dst, return allocSize; } -size_t js::gc::TenuringTracer::moveElementsToTenured(NativeObject* dst, - NativeObject* src, - AllocKind dstKind) { +size_t js::gc::TenuringTracer::moveElements(NativeObject* dst, + NativeObject* src, + AllocKind dstKind) { if (src->hasEmptyElements()) { return 0; } @@ -751,7 +919,7 @@ inline void js::gc::TenuringTracer::insertIntoStringFixupList( stringHead = entry; } -JSString* js::gc::TenuringTracer::moveToTenured(JSString* src) { +JSString* js::gc::TenuringTracer::promoteString(JSString* src) { MOZ_ASSERT(IsInsideNursery(src)); MOZ_ASSERT(!src->isExternal()); @@ -762,29 +930,32 @@ JSString* js::gc::TenuringTracer::moveToTenured(JSString* src) { // the atom. Don't do this for dependent strings because they're more // complicated. See StringRelocationOverlay and DeduplicationStringHasher // comments. + MOZ_ASSERT(!src->isAtom()); if (src->isLinear() && src->inStringToAtomCache() && src->isDeduplicatable() && !src->hasBase()) { JSLinearString* linear = &src->asLinear(); JSAtom* atom = runtime()->caches().stringToAtomCache.lookupInMap(linear); - MOZ_ASSERT(atom, "Why was the cache purged before minor GC?"); - - // Only deduplicate if both strings have the same encoding, to not confuse - // dependent strings. - if (src->hasTwoByteChars() == atom->hasTwoByteChars()) { - // The StringToAtomCache isn't used for inline strings (due to the minimum - // length) so canOwnDependentChars must be true for both src and atom. - // This means if there are dependent strings floating around using str's - // chars, they will be able to use the chars from the atom. - static_assert(StringToAtomCache::MinStringLength > - JSFatInlineString::MAX_LENGTH_LATIN1); - static_assert(StringToAtomCache::MinStringLength > - JSFatInlineString::MAX_LENGTH_TWO_BYTE); - MOZ_ASSERT(src->canOwnDependentChars()); - MOZ_ASSERT(atom->canOwnDependentChars()); - - StringRelocationOverlay::forwardCell(src, atom); - gcprobes::PromoteToTenured(src, atom); - return atom; + // The string will not be present in the cache if it was previously promoted + // to the second nursery generation. + if (atom) { + // Only deduplicate if both strings have the same encoding, to not confuse + // dependent strings. + if (src->hasTwoByteChars() == atom->hasTwoByteChars()) { + // The StringToAtomCache isn't used for inline strings (due to the + // minimum length) so canOwnDependentChars must be true for both src and + // atom. This means if there are dependent strings floating around using + // str's chars, they will be able to use the chars from the atom. + static_assert(StringToAtomCache::MinStringLength > + JSFatInlineString::MAX_LENGTH_LATIN1); + static_assert(StringToAtomCache::MinStringLength > + JSFatInlineString::MAX_LENGTH_TWO_BYTE); + MOZ_ASSERT(src->canOwnDependentChars()); + MOZ_ASSERT(atom->canOwnDependentChars()); + + StringRelocationOverlay::forwardCell(src, atom); + gcprobes::PromoteToTenured(src, atom); + return atom; + } } } @@ -798,9 +969,12 @@ JSString* js::gc::TenuringTracer::moveToTenured(JSString* src) { // 3. It is deduplicatable: // The JSString NON_DEDUP_BIT flag is unset. // 4. It matches an entry in stringDeDupSet. + // 5. It is moved to the tenured heap. - if (src->length() < MAX_DEDUPLICATABLE_STRING_LENGTH && src->isLinear() && + if (shouldTenure(zone, JS::TraceKind::String, src) && + src->length() < MAX_DEDUPLICATABLE_STRING_LENGTH && src->isLinear() && src->isDeduplicatable() && stringDeDupSet.isSome()) { + src->clearBitsOnTenure(); auto p = stringDeDupSet->lookupForAdd(src); if (p) { // Deduplicate to the looked-up string! @@ -811,7 +985,7 @@ JSString* js::gc::TenuringTracer::moveToTenured(JSString* src) { return dst; } - dst = allocTenuredString(src, zone, dstKind); + dst = allocString(src, zone, dstKind); using DedupHasher [[maybe_unused]] = DeduplicationStringHasher<JSString*>; MOZ_ASSERT(DedupHasher::hash(src) == DedupHasher::hash(dst), @@ -823,14 +997,17 @@ JSString* js::gc::TenuringTracer::moveToTenured(JSString* src) { stringDeDupSet.reset(); } } else { - dst = allocTenuredString(src, zone, dstKind); - dst->clearNonDeduplicatable(); + dst = allocString(src, zone, dstKind); + if (dst->isTenured()) { + src->clearBitsOnTenure(); + dst->clearBitsOnTenure(); + } } zone->stringStats.ref().noteTenured(src->allocSize()); auto* overlay = StringRelocationOverlay::forwardCell(src, dst); - MOZ_ASSERT(dst->isDeduplicatable()); + MOZ_ASSERT_IF(dst->isTenured() && dst->isLinear(), dst->isDeduplicatable()); if (dst->hasBase() || dst->isRope()) { // dst or one of its leaves might have a base that will be deduplicated. @@ -874,6 +1051,9 @@ void js::gc::TenuringTracer::relocateDependentStringChars( tenuredDependentStr->relocateNonInlineChars<const CharT*>( tenuredRootBase->nonInlineChars<CharT>(nogc), *offset); tenuredDependentStr->setBase(tenuredRootBase); + if (tenuredDependentStr->isTenured() && !tenuredRootBase->isTenured()) { + runtime()->gc.storeBuffer().putWholeCell(tenuredDependentStr); + } return; } @@ -889,7 +1069,7 @@ void js::gc::TenuringTracer::relocateDependentStringChars( // The root base can be in either the nursery or the tenured heap. // dependentStr chars needs to be relocated after traceString if the // root base is in the nursery. - if (!(*rootBase)->isTenured()) { + if (nursery().inCollectedRegion(*rootBase)) { *rootBaseNotYetForwarded = true; const CharT* rootBaseChars = (*rootBase)->nonInlineChars<CharT>(nogc); *offset = dependentStrChars - rootBaseChars; @@ -906,15 +1086,15 @@ void js::gc::TenuringTracer::relocateDependentStringChars( } } -JS::BigInt* js::gc::TenuringTracer::moveToTenured(JS::BigInt* src) { +JS::BigInt* js::gc::TenuringTracer::promoteBigInt(JS::BigInt* src) { MOZ_ASSERT(IsInsideNursery(src)); AllocKind dstKind = src->getAllocKind(); Zone* zone = src->nurseryZone(); - JS::BigInt* dst = allocTenured<JS::BigInt>(zone, dstKind); - tenuredSize += moveBigIntToTenured(dst, src, dstKind); - tenuredCells++; + JS::BigInt* dst = alloc<JS::BigInt>(zone, dstKind, src); + promotedSize += moveBigInt(dst, src, dstKind); + promotedCells++; RelocationOverlay::forwardCell(src, dst); @@ -924,41 +1104,57 @@ JS::BigInt* js::gc::TenuringTracer::moveToTenured(JS::BigInt* src) { void js::gc::TenuringTracer::collectToObjectFixedPoint() { while (RelocationOverlay* p = objHead) { + MOZ_ASSERT(nursery().inCollectedRegion(p)); objHead = objHead->next(); auto* obj = static_cast<JSObject*>(p->forwardingAddress()); + + MOZ_ASSERT_IF(IsInsideNursery(obj), !nursery().inCollectedRegion(obj)); + + AutoPromotedAnyToNursery promotedAnyToNursery(*this); traceObject(obj); + if (obj->isTenured() && promotedAnyToNursery) { + runtime()->gc.storeBuffer().putWholeCell(obj); + } } } void js::gc::TenuringTracer::collectToStringFixedPoint() { while (StringRelocationOverlay* p = stringHead) { + MOZ_ASSERT(nursery().inCollectedRegion(p)); stringHead = stringHead->next(); - auto* tenuredStr = static_cast<JSString*>(p->forwardingAddress()); + auto* str = static_cast<JSString*>(p->forwardingAddress()); + MOZ_ASSERT_IF(IsInsideNursery(str), !nursery().inCollectedRegion(str)); + // To ensure the NON_DEDUP_BIT was reset properly. - MOZ_ASSERT(tenuredStr->isDeduplicatable()); + MOZ_ASSERT(!str->isAtom()); + MOZ_ASSERT_IF(str->isTenured() && str->isLinear(), str->isDeduplicatable()); // The nursery root base might not be forwarded before - // traceString(tenuredStr). traceString(tenuredStr) will forward the root + // traceString(str). traceString(str) will forward the root // base if that's the case. Dependent string chars needs to be relocated // after traceString if root base was not forwarded. size_t offset = 0; bool rootBaseNotYetForwarded = false; JSLinearString* rootBase = nullptr; - if (tenuredStr->isDependent()) { - if (tenuredStr->hasTwoByteChars()) { + if (str->isDependent()) { + if (str->hasTwoByteChars()) { relocateDependentStringChars<char16_t>( - &tenuredStr->asDependent(), p->savedNurseryBaseOrRelocOverlay(), - &offset, &rootBaseNotYetForwarded, &rootBase); + &str->asDependent(), p->savedNurseryBaseOrRelocOverlay(), &offset, + &rootBaseNotYetForwarded, &rootBase); } else { relocateDependentStringChars<JS::Latin1Char>( - &tenuredStr->asDependent(), p->savedNurseryBaseOrRelocOverlay(), - &offset, &rootBaseNotYetForwarded, &rootBase); + &str->asDependent(), p->savedNurseryBaseOrRelocOverlay(), &offset, + &rootBaseNotYetForwarded, &rootBase); } } - traceString(tenuredStr); + AutoPromotedAnyToNursery promotedAnyToNursery(*this); + traceString(str); + if (str->isTenured() && promotedAnyToNursery) { + runtime()->gc.storeBuffer().putWholeCell(str); + } if (rootBaseNotYetForwarded) { MOZ_ASSERT(rootBase->isForwarded(), @@ -968,25 +1164,34 @@ void js::gc::TenuringTracer::collectToStringFixedPoint() { JSLinearString* tenuredRootBase = Forwarded(rootBase); MOZ_ASSERT(offset < tenuredRootBase->length()); - if (tenuredStr->hasTwoByteChars()) { - tenuredStr->asDependent().relocateNonInlineChars<const char16_t*>( + if (str->hasTwoByteChars()) { + str->asDependent().relocateNonInlineChars<const char16_t*>( tenuredRootBase->twoByteChars(nogc), offset); } else { - tenuredStr->asDependent().relocateNonInlineChars<const JS::Latin1Char*>( + str->asDependent().relocateNonInlineChars<const JS::Latin1Char*>( tenuredRootBase->latin1Chars(nogc), offset); } - tenuredStr->setBase(tenuredRootBase); + + str->setBase(tenuredRootBase); + if (str->isTenured() && !tenuredRootBase->isTenured()) { + runtime()->gc.storeBuffer().putWholeCell(str); + } + } + + if (str->hasBase()) { + MOZ_ASSERT(!str->base()->isForwarded()); + MOZ_ASSERT_IF(!str->base()->isTenured(), + !nursery().inCollectedRegion(str->base())); } } } -size_t js::gc::TenuringTracer::moveStringToTenured(JSString* dst, JSString* src, - AllocKind dstKind) { +size_t js::gc::TenuringTracer::moveString(JSString* dst, JSString* src, + AllocKind dstKind) { size_t size = Arena::thingSize(dstKind); - // At the moment, strings always have the same AllocKind between src and - // dst. This may change in the future. - MOZ_ASSERT(dst->asTenured().getAllocKind() == src->getAllocKind()); + MOZ_ASSERT_IF(dst->isTenured(), + dst->asTenured().getAllocKind() == src->getAllocKind()); // Copy the Cell contents. MOZ_ASSERT(OffsetToChunkEnd(src) >= size); @@ -999,7 +1204,8 @@ size_t js::gc::TenuringTracer::moveStringToTenured(JSString* dst, JSString* src, if (src->ownsMallocedChars()) { void* chars = src->asLinear().nonInlineCharsRaw(); nursery().removeMallocedBufferDuringMinorGC(chars); - AddCellMemory(dst, dst->asLinear().allocSize(), MemoryUse::StringContents); + nursery().trackMallocedBufferOnPromotion( + chars, dst, dst->asLinear().allocSize(), MemoryUse::StringContents); return size; } @@ -1016,14 +1222,12 @@ size_t js::gc::TenuringTracer::moveStringToTenured(JSString* dst, JSString* src, return size; } -size_t js::gc::TenuringTracer::moveBigIntToTenured(JS::BigInt* dst, - JS::BigInt* src, - AllocKind dstKind) { +size_t js::gc::TenuringTracer::moveBigInt(JS::BigInt* dst, JS::BigInt* src, + AllocKind dstKind) { size_t size = Arena::thingSize(dstKind); - // At the moment, BigInts always have the same AllocKind between src and - // dst. This may change in the future. - MOZ_ASSERT(dst->asTenured().getAllocKind() == src->getAllocKind()); + MOZ_ASSERT_IF(dst->isTenured(), + dst->asTenured().getAllocKind() == src->getAllocKind()); // Copy the Cell contents. MOZ_ASSERT(OffsetToChunkEnd(src) >= size); diff --git a/js/src/gc/Tenuring.h b/js/src/gc/Tenuring.h index 3eca5f4bc3..8bb9efd4f8 100644 --- a/js/src/gc/Tenuring.h +++ b/js/src/gc/Tenuring.h @@ -26,6 +26,8 @@ class AnyRef; namespace gc { +class AllocSite; +class ArenaCellSet; class RelocationOverlay; class StringRelocationOverlay; @@ -39,10 +41,10 @@ struct DeduplicationStringHasher { class TenuringTracer final : public JSTracer { Nursery& nursery_; - // Amount of data moved to the tenured generation during collection. - size_t tenuredSize = 0; - // Number of cells moved to the tenured generation. - size_t tenuredCells = 0; + // Size of data promoted during collection. + size_t promotedSize = 0; + // Number of cells promoted during collection. + size_t promotedCells = 0; // These lists are threaded through the Nursery using the space from // already moved things. The lists are used to fix up the moved things and @@ -59,27 +61,34 @@ class TenuringTracer final : public JSTracer { // collection when out of memory to insert new entries. mozilla::Maybe<StringDeDupSet> stringDeDupSet; + bool tenureEverything; + + // A flag set when a GC thing is promoted to the next nursery generation (as + // opposed to the tenured heap). This is used to check when we need to add an + // edge to the remembered set during nursery collection. + bool promotedToNursery = false; + #define DEFINE_ON_EDGE_METHOD(name, type, _1, _2) \ void on##name##Edge(type** thingp, const char* name) override; JS_FOR_EACH_TRACEKIND(DEFINE_ON_EDGE_METHOD) #undef DEFINE_ON_EDGE_METHOD public: - TenuringTracer(JSRuntime* rt, Nursery* nursery); + TenuringTracer(JSRuntime* rt, Nursery* nursery, bool tenureEverything); Nursery& nursery() { return nursery_; } - // Move all objects and everything they can reach to the tenured heap. Called - // after all roots have been traced. + // Promote all live objects and everything they can reach. Called after all + // roots have been traced. void collectToObjectFixedPoint(); - // Move all strings and all strings they can reach to the tenured heap, and - // additionally do any fixups for when strings are pointing into memory that - // was deduplicated. Called after collectToObjectFixedPoint(). + // Promote all live strings and all strings they can reach, and additionally + // do any fixups for when strings are pointing into memory that was + // deduplicated. Called after collectToObjectFixedPoint(). void collectToStringFixedPoint(); - size_t getTenuredSize() const; - size_t getTenuredCells() const; + size_t getPromotedSize() const; + size_t getPromotedCells() const; void traverse(JS::Value* thingp); void traverse(wasm::AnyRef* thingp); @@ -87,14 +96,26 @@ class TenuringTracer final : public JSTracer { // The store buffers need to be able to call these directly. void traceObject(JSObject* obj); void traceObjectSlots(NativeObject* nobj, uint32_t start, uint32_t end); - void traceSlots(JS::Value* vp, uint32_t nslots); + void traceObjectElements(JS::Value* vp, uint32_t count); void traceString(JSString* str); void traceBigInt(JS::BigInt* bi); + // Methods to promote a live cell or get the pointer to its new location if + // that has already happened. The store buffers call these. + JSObject* promoteOrForward(JSObject* obj); + JSString* promoteOrForward(JSString* str); + JS::BigInt* promoteOrForward(JS::BigInt* bip); + + // Returns whether any cells in the arena require sweeping. + template <typename T> + bool traceBufferedCells(Arena* arena, ArenaCellSet* cells); + + class AutoPromotedAnyToNursery; + private: - MOZ_ALWAYS_INLINE void onNonForwardedNurseryObjectEdge(JSObject** objp); - MOZ_ALWAYS_INLINE void onNonForwardedNurseryStringEdge(JSString** strp); - MOZ_ALWAYS_INLINE void onNonForwardedNurseryBigIntEdge(JS::BigInt** bip); + MOZ_ALWAYS_INLINE JSObject* onNonForwardedNurseryObject(JSObject* obj); + MOZ_ALWAYS_INLINE JSString* onNonForwardedNurseryString(JSString* str); + MOZ_ALWAYS_INLINE JS::BigInt* onNonForwardedNurseryBigInt(JS::BigInt* bi); // The dependent string chars needs to be relocated if the base which it's // using chars from has been deduplicated. @@ -109,22 +130,24 @@ class TenuringTracer final : public JSTracer { inline void insertIntoStringFixupList(gc::StringRelocationOverlay* entry); template <typename T> - inline T* allocTenured(JS::Zone* zone, gc::AllocKind kind); - JSString* allocTenuredString(JSString* src, JS::Zone* zone, - gc::AllocKind dstKind); - - inline JSObject* movePlainObjectToTenured(PlainObject* src); - JSObject* moveToTenuredSlow(JSObject* src); - JSString* moveToTenured(JSString* src); - JS::BigInt* moveToTenured(JS::BigInt* src); - - size_t moveElementsToTenured(NativeObject* dst, NativeObject* src, - gc::AllocKind dstKind); - size_t moveSlotsToTenured(NativeObject* dst, NativeObject* src); - size_t moveStringToTenured(JSString* dst, JSString* src, - gc::AllocKind dstKind); - size_t moveBigIntToTenured(JS::BigInt* dst, JS::BigInt* src, - gc::AllocKind dstKind); + T* alloc(JS::Zone* zone, gc::AllocKind kind, gc::Cell* src); + template <JS::TraceKind traceKind> + void* allocCell(JS::Zone* zone, gc::AllocKind allocKind, gc::AllocSite* site, + gc::Cell* src); + JSString* allocString(JSString* src, JS::Zone* zone, gc::AllocKind dstKind); + + bool shouldTenure(Zone* zone, JS::TraceKind traceKind, Cell* cell); + + inline JSObject* promotePlainObject(PlainObject* src); + JSObject* promoteObjectSlow(JSObject* src); + JSString* promoteString(JSString* src); + JS::BigInt* promoteBigInt(JS::BigInt* src); + + size_t moveElements(NativeObject* dst, NativeObject* src, + gc::AllocKind dstKind); + size_t moveSlots(NativeObject* dst, NativeObject* src); + size_t moveString(JSString* dst, JSString* src, gc::AllocKind dstKind); + size_t moveBigInt(JS::BigInt* dst, JS::BigInt* src, gc::AllocKind dstKind); void traceSlots(JS::Value* vp, JS::Value* end); }; diff --git a/js/src/gc/TraceMethods-inl.h b/js/src/gc/TraceMethods-inl.h index 37da24fe6e..e7066c5ebc 100644 --- a/js/src/gc/TraceMethods-inl.h +++ b/js/src/gc/TraceMethods-inl.h @@ -30,6 +30,9 @@ #include "vm/SymbolType.h" #include "wasm/WasmJS.h" +#include "gc/Marking-inl.h" +#include "vm/StringType-inl.h" + inline void js::BaseScript::traceChildren(JSTracer* trc) { TraceNullableEdge(trc, &function_, "function"); TraceEdge(trc, &sourceObject_, "sourceObject"); @@ -76,6 +79,20 @@ inline void JSString::traceChildren(JSTracer* trc) { asRope().traceChildren(trc); } } +inline void JSString::traceBaseFromStoreBuffer(JSTracer* trc) { + MOZ_ASSERT(!d.s.u3.base->isTenured()); + + // Contract the base chain so that this tenured dependent string points + // directly at the root base that owns its chars. + JSLinearString* root = asDependent().rootBaseDuringMinorGC(); + d.s.u3.base = root; + if (!root->isTenured()) { + js::TraceManuallyBarrieredEdge(trc, &root, "base"); + // Do not update the actual base to the tenured string yet. This string will + // need to be swept in order to update its chars ptr to be relative to the + // root, and that update requires information from the overlay. + } +} template <uint32_t opts> void js::GCMarker::eagerlyMarkChildren(JSString* str) { if (str->isLinear()) { diff --git a/js/src/gc/WeakMap-inl.h b/js/src/gc/WeakMap-inl.h index 015e5071ed..d7b5feb5a6 100644 --- a/js/src/gc/WeakMap-inl.h +++ b/js/src/gc/WeakMap-inl.h @@ -18,6 +18,7 @@ #include "gc/GCLock.h" #include "gc/Marking.h" #include "gc/Zone.h" +#include "js/Prefs.h" #include "js/TraceKind.h" #include "vm/JSContext.h" @@ -71,6 +72,16 @@ static inline JSObject* GetDelegate(const T& key) { template <> inline JSObject* GetDelegate(gc::Cell* const&) = delete; +template <typename T> +static inline bool IsSymbol(const T& key) { + return false; +} + +template <> +inline bool IsSymbol(const HeapPtr<JS::Value>& key) { + return key.isSymbol(); +} + } // namespace gc::detail // Weakmap entry -> value edges are only visible if the map is traced, which @@ -303,25 +314,42 @@ bool WeakMap<K, V>::findSweepGroupEdges() { for (Range r = all(); !r.empty(); r.popFront()) { const K& key = r.front().key(); - // If the key type doesn't have delegates, then this will always return - // nullptr and the optimizer can remove the entire body of this function. JSObject* delegate = gc::detail::GetDelegate(key); - if (!delegate) { + if (delegate) { + // Marking a WeakMap key's delegate will mark the key, so process the + // delegate zone no later than the key zone. + Zone* delegateZone = delegate->zone(); + gc::Cell* keyCell = gc::ToMarkable(key); + MOZ_ASSERT(keyCell); + Zone* keyZone = keyCell->zone(); + if (delegateZone != keyZone && delegateZone->isGCMarking() && + keyZone->isGCMarking()) { + if (!delegateZone->addSweepGroupEdgeTo(keyZone)) { + return false; + } + } + } + +#ifdef NIGHTLY_BUILD + bool symbolsAsWeakMapKeysEnabled = + JS::Prefs::experimental_symbols_as_weakmap_keys(); + if (!symbolsAsWeakMapKeysEnabled) { continue; } - // Marking a WeakMap key's delegate will mark the key, so process the - // delegate zone no later than the key zone. - Zone* delegateZone = delegate->zone(); - gc::Cell* keyCell = gc::ToMarkable(key); - MOZ_ASSERT(keyCell); - Zone* keyZone = keyCell->zone(); - if (delegateZone != keyZone && delegateZone->isGCMarking() && - keyZone->isGCMarking()) { - if (!delegateZone->addSweepGroupEdgeTo(keyZone)) { - return false; + bool isSym = gc::detail::IsSymbol(key); + if (isSym) { + gc::Cell* keyCell = gc::ToMarkable(key); + Zone* keyZone = keyCell->zone(); + MOZ_ASSERT(keyZone->isAtomsZone()); + + if (zone()->isGCMarking() && keyZone->isGCMarking()) { + if (!keyZone->addSweepGroupEdgeTo(zone())) { + return false; + } } } +#endif } return true; } diff --git a/js/src/gc/Zone.cpp b/js/src/gc/Zone.cpp index d0586d5d56..6437f6f4c3 100644 --- a/js/src/gc/Zone.cpp +++ b/js/src/gc/Zone.cpp @@ -622,7 +622,7 @@ void Zone::fixupAfterMovingGC() { } void Zone::purgeAtomCache() { - atomCache().clearAndCompact(); + atomCache_.ref().reset(); // Also purge the dtoa caches so that subsequent lookups populate atom // cache too. @@ -981,20 +981,3 @@ bool Zone::registerObjectWithWeakPointers(JSObject* obj) { MOZ_ASSERT(!IsInsideNursery(obj)); return objectsWithWeakPointers.ref().append(obj); } - -js::DependentScriptSet* Zone::getOrCreateDependentScriptSet( - JSContext* cx, js::InvalidatingFuse* fuse) { - for (auto& dss : fuseDependencies) { - if (dss.associatedFuse == fuse) { - return &dss; - } - } - - if (!fuseDependencies.emplaceBack(cx, fuse)) { - return nullptr; - } - - auto& dss = fuseDependencies.back(); - MOZ_ASSERT(dss.associatedFuse == fuse); - return &dss; -} diff --git a/js/src/gc/Zone.h b/js/src/gc/Zone.h index fd91de8626..a5ce161cc4 100644 --- a/js/src/gc/Zone.h +++ b/js/src/gc/Zone.h @@ -15,6 +15,8 @@ #include "mozilla/PodOperations.h" #include "mozilla/TimeStamp.h" +#include <array> + #include "jstypes.h" #include "ds/Bitmap.h" @@ -139,6 +141,148 @@ class MOZ_NON_TEMPORARY_CLASS FunctionToStringCache { MOZ_ALWAYS_INLINE void put(BaseScript* script, JSString* string); }; +// HashAndLength is a simple class encapsulating the combination of a HashNumber +// and a (string) length into a single 64-bit value. Having them bundled +// together like this enables us to compare pairs of hashes and lengths with a +// single 64-bit comparison. +class HashAndLength { + public: + MOZ_ALWAYS_INLINE explicit HashAndLength(uint64_t initialValue = unsetValue()) + : mHashAndLength(initialValue) {} + MOZ_ALWAYS_INLINE HashAndLength(HashNumber hash, uint32_t length) + : mHashAndLength(uint64FromHashAndLength(hash, length)) {} + + void MOZ_ALWAYS_INLINE set(HashNumber hash, uint32_t length) { + mHashAndLength = uint64FromHashAndLength(hash, length); + } + + constexpr MOZ_ALWAYS_INLINE HashNumber hash() const { + return hashFromUint64(mHashAndLength); + } + constexpr MOZ_ALWAYS_INLINE uint32_t length() const { + return lengthFromUint64(mHashAndLength); + } + + constexpr MOZ_ALWAYS_INLINE bool isEqual(HashNumber hash, + uint32_t length) const { + return mHashAndLength == uint64FromHashAndLength(hash, length); + } + + // This function is used at compile-time to verify and that we pack and unpack + // hash and length values consistently. + static constexpr bool staticChecks() { + std::array<HashNumber, 5> hashes{0x00000000, 0xffffffff, 0xf0f0f0f0, + 0x0f0f0f0f, 0x73737373}; + std::array<uint32_t, 6> lengths{0, 1, 2, 3, 11, 56}; + + for (const HashNumber hash : hashes) { + for (const uint32_t length : lengths) { + const uint64_t lengthAndHash = uint64FromHashAndLength(hash, length); + if (hashFromUint64(lengthAndHash) != hash) { + return false; + } + if (lengthFromUint64(lengthAndHash) != length) { + return false; + } + } + } + + return true; + } + + static constexpr MOZ_ALWAYS_INLINE uint64_t unsetValue() { + // This needs to be a combination of hash and length that would never occur + // together. There is only one string of length zero, and its hash is zero, + // so the hash here can be anything except zero. + return uint64FromHashAndLength(0xffffffff, 0); + } + + private: + uint64_t mHashAndLength; + + static constexpr MOZ_ALWAYS_INLINE uint64_t + uint64FromHashAndLength(HashNumber hash, uint32_t length) { + return (static_cast<uint64_t>(length) << 32) | hash; + } + + static constexpr MOZ_ALWAYS_INLINE uint32_t + lengthFromUint64(uint64_t hashAndLength) { + return static_cast<uint32_t>(hashAndLength >> 32); + } + + static constexpr MOZ_ALWAYS_INLINE HashNumber + hashFromUint64(uint64_t hashAndLength) { + return hashAndLength & 0xffffffff; + } +}; + +static_assert(HashAndLength::staticChecks()); + +class AtomCacheHashTable { + public: + MOZ_ALWAYS_INLINE AtomCacheHashTable() { clear(); } + + MOZ_ALWAYS_INLINE void clear() { + mEntries.fill({HashAndLength{HashAndLength::unsetValue()}, nullptr}); + } + + static MOZ_ALWAYS_INLINE constexpr uint32_t computeIndexFromHash( + const HashNumber hash) { + // Simply use the low bits of the hash value as the cache index. + return hash & (sSize - 1); + } + + MOZ_ALWAYS_INLINE JSAtom* lookupForAdd( + const AtomHasher::Lookup& lookup) const { + MOZ_ASSERT(lookup.atom == nullptr, "Lookup by atom is not supported"); + + const uint32_t index = computeIndexFromHash(lookup.hash); + + JSAtom* const atom = mEntries[index].mAtom; + + if (!mEntries[index].mHashAndLength.isEqual(lookup.hash, lookup.length)) { + return nullptr; + } + + // This is annotated with MOZ_UNLIKELY because it virtually never happens + // that, after matching the hash and the length, the string isn't a match. + if (MOZ_UNLIKELY(!lookup.StringsMatch(*atom))) { + return nullptr; + } + + return atom; + } + + MOZ_ALWAYS_INLINE void add(const HashNumber hash, JSAtom* atom) { + const uint32_t index = computeIndexFromHash(hash); + + mEntries[index].set(hash, atom->length(), atom); + } + + private: + struct Entry { + MOZ_ALWAYS_INLINE void set(const HashNumber hash, const uint32_t length, + JSAtom* const atom) { + mHashAndLength.set(hash, length); + mAtom = atom; + } + + // Hash and length are also available, from JSAtom and JSString + // respectively, but are cached here to avoid likely cache misses in the + // frequent case of a missed lookup. + HashAndLength mHashAndLength; + // No read barrier is required here because the table is cleared at the + // start of GC. + JSAtom* mAtom; + }; + + // This value was picked empirically based on performance testing using SP2 + // and SP3. 4k was better than 2k but 8k was not much better than 4k. + static constexpr uint32_t sSize = 4 * 1024; + static_assert(mozilla::IsPowerOfTwo(sSize)); + std::array<Entry, sSize> mEntries; +}; + } // namespace js namespace JS { @@ -281,7 +425,7 @@ class Zone : public js::ZoneAllocator, public js::gc::GraphNodeBase<JS::Zone> { js::MainThreadOrGCTaskData<js::SparseBitmap> markedAtoms_; // Set of atoms recently used by this Zone. Purged on GC. - js::MainThreadOrGCTaskData<js::AtomSet> atomCache_; + js::MainThreadOrGCTaskData<js::UniquePtr<js::AtomCacheHashTable>> atomCache_; // Cache storing allocated external strings. Purged on GC. js::MainThreadOrGCTaskData<js::ExternalStringCache> externalStringCache_; @@ -613,7 +757,16 @@ class Zone : public js::ZoneAllocator, public js::gc::GraphNodeBase<JS::Zone> { js::SparseBitmap& markedAtoms() { return markedAtoms_.ref(); } - js::AtomSet& atomCache() { return atomCache_.ref(); } + // The atom cache is "allocate-on-demand". This function can return nullptr if + // the allocation failed. + js::AtomCacheHashTable* atomCache() { + if (atomCache_.ref()) { + return atomCache_.ref().get(); + } + + atomCache_ = js::MakeUnique<js::AtomCacheHashTable>(); + return atomCache_.ref().get(); + } void purgeAtomCache(); @@ -677,18 +830,7 @@ class Zone : public js::ZoneAllocator, public js::gc::GraphNodeBase<JS::Zone> { #endif // Support for invalidating fuses - - // A dependent script set pairs a fuse with a set of scripts which depend - // on said fuse; this is a vector of script sets because the expectation for - // now is that the number of runtime wide invalidating fuses will be small. - // This will need to be revisited (convert to HashMap?) should that no - // longer be the case - // - // Note: This isn't traced through the zone, but rather through the use - // of JS::WeakCache. - js::Vector<js::DependentScriptSet, 1, js::SystemAllocPolicy> fuseDependencies; - js::DependentScriptSet* getOrCreateDependentScriptSet( - JSContext* cx, js::InvalidatingFuse* fuse); + js::DependentScriptGroup fuseDependencies; private: js::jit::JitZone* createJitZone(JSContext* cx); |