// Copyright 2012 the V8 project authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. #include "src/heap/heap.h" #include #include #include "src/accessors.h" #include "src/api-inl.h" #include "src/assembler-inl.h" #include "src/ast/context-slot-cache.h" #include "src/base/bits.h" #include "src/base/once.h" #include "src/base/utils/random-number-generator.h" #include "src/bootstrapper.h" #include "src/code-stubs.h" #include "src/compilation-cache.h" #include "src/conversions.h" #include "src/debug/debug.h" #include "src/deoptimizer.h" #include "src/feedback-vector.h" #include "src/global-handles.h" #include "src/heap/array-buffer-collector.h" #include "src/heap/array-buffer-tracker-inl.h" #include "src/heap/barrier.h" #include "src/heap/code-stats.h" #include "src/heap/concurrent-marking.h" #include "src/heap/embedder-tracing.h" #include "src/heap/gc-idle-time-handler.h" #include "src/heap/gc-tracer.h" #include "src/heap/heap-controller.h" #include "src/heap/heap-write-barrier-inl.h" #include "src/heap/incremental-marking.h" #include "src/heap/mark-compact-inl.h" #include "src/heap/mark-compact.h" #include "src/heap/memory-reducer.h" #include "src/heap/object-stats.h" #include "src/heap/objects-visiting-inl.h" #include "src/heap/objects-visiting.h" #include "src/heap/remembered-set.h" #include "src/heap/scavenge-job.h" #include "src/heap/scavenger-inl.h" #include "src/heap/store-buffer.h" #include "src/heap/stress-marking-observer.h" #include "src/heap/stress-scavenge-observer.h" #include "src/heap/sweeper.h" #include "src/instruction-stream.h" #include "src/interpreter/interpreter.h" #include "src/objects/data-handler.h" #include "src/objects/hash-table-inl.h" #include "src/objects/maybe-object.h" #include "src/objects/shared-function-info.h" #include "src/regexp/jsregexp.h" #include "src/runtime-profiler.h" #include "src/snapshot/natives.h" #include "src/snapshot/serializer-common.h" #include "src/snapshot/snapshot.h" #include "src/tracing/trace-event.h" #include "src/unicode-decoder.h" #include "src/unicode-inl.h" #include "src/utils-inl.h" #include "src/utils.h" #include "src/v8.h" #include "src/vm-state-inl.h" // Has to be the last include (doesn't have include guards): #include "src/objects/object-macros.h" namespace v8 { namespace internal { void Heap::SetArgumentsAdaptorDeoptPCOffset(int pc_offset) { DCHECK_EQ(Smi::kZero, arguments_adaptor_deopt_pc_offset()); set_arguments_adaptor_deopt_pc_offset(Smi::FromInt(pc_offset)); } void Heap::SetConstructStubCreateDeoptPCOffset(int pc_offset) { DCHECK(construct_stub_create_deopt_pc_offset() == Smi::kZero); set_construct_stub_create_deopt_pc_offset(Smi::FromInt(pc_offset)); } void Heap::SetConstructStubInvokeDeoptPCOffset(int pc_offset) { DCHECK(construct_stub_invoke_deopt_pc_offset() == Smi::kZero); set_construct_stub_invoke_deopt_pc_offset(Smi::FromInt(pc_offset)); } void Heap::SetInterpreterEntryReturnPCOffset(int pc_offset) { DCHECK_EQ(Smi::kZero, interpreter_entry_return_pc_offset()); set_interpreter_entry_return_pc_offset(Smi::FromInt(pc_offset)); } void Heap::SetSerializedObjects(FixedArray* objects) { DCHECK(isolate()->serializer_enabled()); set_serialized_objects(objects); } void Heap::SetSerializedGlobalProxySizes(FixedArray* sizes) { DCHECK(isolate()->serializer_enabled()); set_serialized_global_proxy_sizes(sizes); } bool Heap::GCCallbackTuple::operator==( const Heap::GCCallbackTuple& other) const { return other.callback == callback && other.data == data; } Heap::GCCallbackTuple& Heap::GCCallbackTuple::operator=( const Heap::GCCallbackTuple& other) = default; struct Heap::StrongRootsList { Object** start; Object** end; StrongRootsList* next; }; class IdleScavengeObserver : public AllocationObserver { public: IdleScavengeObserver(Heap& heap, intptr_t step_size) : AllocationObserver(step_size), heap_(heap) {} void Step(int bytes_allocated, Address, size_t) override { heap_.ScheduleIdleScavengeIfNeeded(bytes_allocated); } private: Heap& heap_; }; Heap::Heap() : initial_max_old_generation_size_(max_old_generation_size_), initial_old_generation_size_(max_old_generation_size_ / kInitalOldGenerationLimitFactor), memory_pressure_level_(MemoryPressureLevel::kNone), old_generation_allocation_limit_(initial_old_generation_size_), global_pretenuring_feedback_(kInitialFeedbackCapacity), current_gc_callback_flags_(GCCallbackFlags::kNoGCCallbackFlags), external_string_table_(this) { // Ensure old_generation_size_ is a multiple of kPageSize. DCHECK_EQ(0, max_old_generation_size_ & (Page::kPageSize - 1)); set_native_contexts_list(nullptr); set_allocation_sites_list(Smi::kZero); // Put a dummy entry in the remembered pages so we can find the list the // minidump even if there are no real unmapped pages. RememberUnmappedPage(kNullAddress, false); } size_t Heap::MaxReserved() { const double kFactor = Page::kPageSize * 1.0 / Page::kAllocatableMemory; return static_cast( (2 * max_semi_space_size_ + max_old_generation_size_) * kFactor); } size_t Heap::ComputeMaxOldGenerationSize(uint64_t physical_memory) { const size_t old_space_physical_memory_factor = 4; size_t computed_size = static_cast(physical_memory / i::MB / old_space_physical_memory_factor * kPointerMultiplier); return Max(Min(computed_size, HeapController::kMaxSize), HeapController::kMinSize); } size_t Heap::Capacity() { if (!HasBeenSetUp()) return 0; return new_space_->Capacity() + OldGenerationCapacity(); } size_t Heap::OldGenerationCapacity() { if (!HasBeenSetUp()) return 0; PagedSpaces spaces(this, PagedSpaces::SpacesSpecifier::kAllPagedSpaces); size_t total = 0; for (PagedSpace* space = spaces.next(); space != nullptr; space = spaces.next()) { total += space->Capacity(); } return total + lo_space_->SizeOfObjects(); } size_t Heap::CommittedOldGenerationMemory() { if (!HasBeenSetUp()) return 0; PagedSpaces spaces(this, PagedSpaces::SpacesSpecifier::kAllPagedSpaces); size_t total = 0; for (PagedSpace* space = spaces.next(); space != nullptr; space = spaces.next()) { total += space->CommittedMemory(); } return total + lo_space_->Size(); } size_t Heap::CommittedMemoryOfHeapAndUnmapper() { if (!HasBeenSetUp()) return 0; return CommittedMemory() + memory_allocator()->unmapper()->CommittedBufferedMemory(); } size_t Heap::CommittedMemory() { if (!HasBeenSetUp()) return 0; return new_space_->CommittedMemory() + CommittedOldGenerationMemory(); } size_t Heap::CommittedPhysicalMemory() { if (!HasBeenSetUp()) return 0; size_t total = 0; for (SpaceIterator it(this); it.has_next();) { total += it.next()->CommittedPhysicalMemory(); } return total; } size_t Heap::CommittedMemoryExecutable() { if (!HasBeenSetUp()) return 0; return static_cast(memory_allocator()->SizeExecutable()); } void Heap::UpdateMaximumCommitted() { if (!HasBeenSetUp()) return; const size_t current_committed_memory = CommittedMemory(); if (current_committed_memory > maximum_committed_) { maximum_committed_ = current_committed_memory; } } size_t Heap::Available() { if (!HasBeenSetUp()) return 0; size_t total = 0; for (SpaceIterator it(this); it.has_next();) { total += it.next()->Available(); } return total; } bool Heap::CanExpandOldGeneration(size_t size) { if (force_oom_) return false; if (OldGenerationCapacity() + size > MaxOldGenerationSize()) return false; // The OldGenerationCapacity does not account compaction spaces used // during evacuation. Ensure that expanding the old generation does push // the total allocated memory size over the maximum heap size. return memory_allocator()->Size() + size <= MaxReserved(); } bool Heap::HasBeenSetUp() { // We will always have a new space when the heap is set up. return new_space_ != nullptr; } GarbageCollector Heap::SelectGarbageCollector(AllocationSpace space, const char** reason) { // Is global GC requested? if (space != NEW_SPACE) { isolate_->counters()->gc_compactor_caused_by_request()->Increment(); *reason = "GC in old space requested"; return MARK_COMPACTOR; } if (FLAG_gc_global || (FLAG_stress_compaction && (gc_count_ & 1) != 0)) { *reason = "GC in old space forced by flags"; return MARK_COMPACTOR; } if (incremental_marking()->NeedsFinalization() && AllocationLimitOvershotByLargeMargin()) { *reason = "Incremental marking needs finalization"; return MARK_COMPACTOR; } // Over-estimate the new space size using capacity to allow some slack. if (!CanExpandOldGeneration(new_space_->TotalCapacity())) { isolate_->counters() ->gc_compactor_caused_by_oldspace_exhaustion() ->Increment(); *reason = "scavenge might not succeed"; return MARK_COMPACTOR; } // Default *reason = nullptr; return YoungGenerationCollector(); } void Heap::SetGCState(HeapState state) { gc_state_ = state; } void Heap::PrintShortHeapStatistics() { if (!FLAG_trace_gc_verbose) return; PrintIsolate(isolate_, "Memory allocator, used: %6" PRIuS " KB," " available: %6" PRIuS " KB\n", memory_allocator()->Size() / KB, memory_allocator()->Available() / KB); PrintIsolate(isolate_, "Read-only space, used: %6" PRIuS " KB" ", available: %6" PRIuS " KB" ", committed: %6" PRIuS " KB\n", read_only_space_->Size() / KB, read_only_space_->Available() / KB, read_only_space_->CommittedMemory() / KB); PrintIsolate(isolate_, "New space, used: %6" PRIuS " KB" ", available: %6" PRIuS " KB" ", committed: %6" PRIuS " KB\n", new_space_->Size() / KB, new_space_->Available() / KB, new_space_->CommittedMemory() / KB); PrintIsolate(isolate_, "New large object space, used: %6" PRIuS " KB" ", available: %6" PRIuS " KB" ", committed: %6" PRIuS " KB\n", new_lo_space_->SizeOfObjects() / KB, new_lo_space_->Available() / KB, new_lo_space_->CommittedMemory() / KB); PrintIsolate(isolate_, "Old space, used: %6" PRIuS " KB" ", available: %6" PRIuS " KB" ", committed: %6" PRIuS " KB\n", old_space_->SizeOfObjects() / KB, old_space_->Available() / KB, old_space_->CommittedMemory() / KB); PrintIsolate(isolate_, "Code space, used: %6" PRIuS " KB" ", available: %6" PRIuS " KB" ", committed: %6" PRIuS "KB\n", code_space_->SizeOfObjects() / KB, code_space_->Available() / KB, code_space_->CommittedMemory() / KB); PrintIsolate(isolate_, "Map space, used: %6" PRIuS " KB" ", available: %6" PRIuS " KB" ", committed: %6" PRIuS " KB\n", map_space_->SizeOfObjects() / KB, map_space_->Available() / KB, map_space_->CommittedMemory() / KB); PrintIsolate(isolate_, "Large object space, used: %6" PRIuS " KB" ", available: %6" PRIuS " KB" ", committed: %6" PRIuS " KB\n", lo_space_->SizeOfObjects() / KB, lo_space_->Available() / KB, lo_space_->CommittedMemory() / KB); PrintIsolate(isolate_, "All spaces, used: %6" PRIuS " KB" ", available: %6" PRIuS " KB" ", committed: %6" PRIuS "KB\n", this->SizeOfObjects() / KB, this->Available() / KB, this->CommittedMemory() / KB); PrintIsolate(isolate_, "Unmapper buffering %d chunks of committed: %6" PRIuS " KB\n", memory_allocator()->unmapper()->NumberOfChunks(), CommittedMemoryOfHeapAndUnmapper() / KB); PrintIsolate(isolate_, "External memory reported: %6" PRId64 " KB\n", external_memory_ / KB); PrintIsolate(isolate_, "Backing store memory: %6" PRIuS " KB\n", backing_store_bytes_ / KB); PrintIsolate(isolate_, "External memory global %zu KB\n", external_memory_callback_() / KB); PrintIsolate(isolate_, "Total time spent in GC : %.1f ms\n", total_gc_time_ms_); } void Heap::ReportStatisticsAfterGC() { for (int i = 0; i < static_cast(v8::Isolate::kUseCounterFeatureCount); ++i) { int count = deferred_counters_[i]; deferred_counters_[i] = 0; while (count > 0) { count--; isolate()->CountUsage(static_cast(i)); } } } void Heap::AddHeapObjectAllocationTracker( HeapObjectAllocationTracker* tracker) { if (allocation_trackers_.empty()) DisableInlineAllocation(); allocation_trackers_.push_back(tracker); } void Heap::RemoveHeapObjectAllocationTracker( HeapObjectAllocationTracker* tracker) { allocation_trackers_.erase(std::remove(allocation_trackers_.begin(), allocation_trackers_.end(), tracker), allocation_trackers_.end()); if (allocation_trackers_.empty()) EnableInlineAllocation(); } void Heap::AddRetainingPathTarget(Handle object, RetainingPathOption option) { if (!FLAG_track_retaining_path) { PrintF("Retaining path tracking requires --track-retaining-path\n"); } else { Handle array(retaining_path_targets(), isolate()); int index = array->length(); array = WeakArrayList::AddToEnd(isolate(), array, MaybeObjectHandle::Weak(object)); set_retaining_path_targets(*array); DCHECK_EQ(array->length(), index + 1); retaining_path_target_option_[index] = option; } } bool Heap::IsRetainingPathTarget(HeapObject* object, RetainingPathOption* option) { WeakArrayList* targets = retaining_path_targets(); int length = targets->length(); MaybeObject* object_to_check = HeapObjectReference::Weak(object); for (int i = 0; i < length; i++) { MaybeObject* target = targets->Get(i); DCHECK(target->IsWeakOrCleared()); if (target == object_to_check) { DCHECK(retaining_path_target_option_.count(i)); *option = retaining_path_target_option_[i]; return true; } } return false; } void Heap::PrintRetainingPath(HeapObject* target, RetainingPathOption option) { PrintF("\n\n\n"); PrintF("#################################################\n"); PrintF("Retaining path for %p:\n", static_cast(target)); HeapObject* object = target; std::vector> retaining_path; Root root = Root::kUnknown; bool ephemeron = false; while (true) { retaining_path.push_back(std::make_pair(object, ephemeron)); if (option == RetainingPathOption::kTrackEphemeronPath && ephemeron_retainer_.count(object)) { object = ephemeron_retainer_[object]; ephemeron = true; } else if (retainer_.count(object)) { object = retainer_[object]; ephemeron = false; } else { if (retaining_root_.count(object)) { root = retaining_root_[object]; } break; } } int distance = static_cast(retaining_path.size()); for (auto node : retaining_path) { HeapObject* object = node.first; bool ephemeron = node.second; PrintF("\n"); PrintF("^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n"); PrintF("Distance from root %d%s: ", distance, ephemeron ? " (ephemeron)" : ""); object->ShortPrint(); PrintF("\n"); #ifdef OBJECT_PRINT object->Print(); PrintF("\n"); #endif --distance; } PrintF("\n"); PrintF("^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n"); PrintF("Root: %s\n", RootVisitor::RootName(root)); PrintF("-------------------------------------------------\n"); } void Heap::AddRetainer(HeapObject* retainer, HeapObject* object) { if (retainer_.count(object)) return; retainer_[object] = retainer; RetainingPathOption option = RetainingPathOption::kDefault; if (IsRetainingPathTarget(object, &option)) { // Check if the retaining path was already printed in // AddEphemeronRetainer(). if (ephemeron_retainer_.count(object) == 0 || option == RetainingPathOption::kDefault) { PrintRetainingPath(object, option); } } } void Heap::AddEphemeronRetainer(HeapObject* retainer, HeapObject* object) { if (ephemeron_retainer_.count(object)) return; ephemeron_retainer_[object] = retainer; RetainingPathOption option = RetainingPathOption::kDefault; if (IsRetainingPathTarget(object, &option) && option == RetainingPathOption::kTrackEphemeronPath) { // Check if the retaining path was already printed in AddRetainer(). if (retainer_.count(object) == 0) { PrintRetainingPath(object, option); } } } void Heap::AddRetainingRoot(Root root, HeapObject* object) { if (retaining_root_.count(object)) return; retaining_root_[object] = root; RetainingPathOption option = RetainingPathOption::kDefault; if (IsRetainingPathTarget(object, &option)) { PrintRetainingPath(object, option); } } void Heap::IncrementDeferredCount(v8::Isolate::UseCounterFeature feature) { deferred_counters_[feature]++; } bool Heap::UncommitFromSpace() { return new_space_->UncommitFromSpace(); } void Heap::GarbageCollectionPrologue() { TRACE_GC(tracer(), GCTracer::Scope::HEAP_PROLOGUE); { AllowHeapAllocation for_the_first_part_of_prologue; gc_count_++; #ifdef VERIFY_HEAP if (FLAG_verify_heap) { Verify(); } #endif } // Reset GC statistics. promoted_objects_size_ = 0; previous_semi_space_copied_object_size_ = semi_space_copied_object_size_; semi_space_copied_object_size_ = 0; nodes_died_in_new_space_ = 0; nodes_copied_in_new_space_ = 0; nodes_promoted_ = 0; UpdateMaximumCommitted(); #ifdef DEBUG DCHECK(!AllowHeapAllocation::IsAllowed() && gc_state_ == NOT_IN_GC); if (FLAG_gc_verbose) Print(); #endif // DEBUG if (new_space_->IsAtMaximumCapacity()) { maximum_size_scavenges_++; } else { maximum_size_scavenges_ = 0; } CheckNewSpaceExpansionCriteria(); UpdateNewSpaceAllocationCounter(); if (FLAG_track_retaining_path) { retainer_.clear(); ephemeron_retainer_.clear(); retaining_root_.clear(); } } size_t Heap::SizeOfObjects() { size_t total = 0; for (SpaceIterator it(this); it.has_next();) { total += it.next()->SizeOfObjects(); } return total; } const char* Heap::GetSpaceName(int idx) { switch (idx) { case NEW_SPACE: return "new_space"; case OLD_SPACE: return "old_space"; case MAP_SPACE: return "map_space"; case CODE_SPACE: return "code_space"; case LO_SPACE: return "large_object_space"; case NEW_LO_SPACE: return "new_large_object_space"; case RO_SPACE: return "read_only_space"; default: UNREACHABLE(); } return nullptr; } void Heap::SetRootCodeStubs(SimpleNumberDictionary* value) { roots_[RootIndex::kCodeStubs] = value; } void Heap::RepairFreeListsAfterDeserialization() { PagedSpaces spaces(this); for (PagedSpace* space = spaces.next(); space != nullptr; space = spaces.next()) { space->RepairFreeListsAfterDeserialization(); } } void Heap::MergeAllocationSitePretenuringFeedback( const PretenuringFeedbackMap& local_pretenuring_feedback) { AllocationSite* site = nullptr; for (auto& site_and_count : local_pretenuring_feedback) { site = site_and_count.first; MapWord map_word = site_and_count.first->map_word(); if (map_word.IsForwardingAddress()) { site = AllocationSite::cast(map_word.ToForwardingAddress()); } // We have not validated the allocation site yet, since we have not // dereferenced the site during collecting information. // This is an inlined check of AllocationMemento::IsValid. if (!site->IsAllocationSite() || site->IsZombie()) continue; const int value = static_cast(site_and_count.second); DCHECK_LT(0, value); if (site->IncrementMementoFoundCount(value)) { // For sites in the global map the count is accessed through the site. global_pretenuring_feedback_.insert(std::make_pair(site, 0)); } } } void Heap::AddAllocationObserversToAllSpaces( AllocationObserver* observer, AllocationObserver* new_space_observer) { DCHECK(observer && new_space_observer); for (SpaceIterator it(this); it.has_next();) { Space* space = it.next(); if (space == new_space()) { space->AddAllocationObserver(new_space_observer); } else { space->AddAllocationObserver(observer); } } } void Heap::RemoveAllocationObserversFromAllSpaces( AllocationObserver* observer, AllocationObserver* new_space_observer) { DCHECK(observer && new_space_observer); for (SpaceIterator it(this); it.has_next();) { Space* space = it.next(); if (space == new_space()) { space->RemoveAllocationObserver(new_space_observer); } else { space->RemoveAllocationObserver(observer); } } } class Heap::SkipStoreBufferScope { public: explicit SkipStoreBufferScope(StoreBuffer* store_buffer) : store_buffer_(store_buffer) { store_buffer_->MoveAllEntriesToRememberedSet(); store_buffer_->SetMode(StoreBuffer::IN_GC); } ~SkipStoreBufferScope() { DCHECK(store_buffer_->Empty()); store_buffer_->SetMode(StoreBuffer::NOT_IN_GC); } private: StoreBuffer* store_buffer_; }; namespace { inline bool MakePretenureDecision( AllocationSite* site, AllocationSite::PretenureDecision current_decision, double ratio, bool maximum_size_scavenge) { // Here we just allow state transitions from undecided or maybe tenure // to don't tenure, maybe tenure, or tenure. if ((current_decision == AllocationSite::kUndecided || current_decision == AllocationSite::kMaybeTenure)) { if (ratio >= AllocationSite::kPretenureRatio) { // We just transition into tenure state when the semi-space was at // maximum capacity. if (maximum_size_scavenge) { site->set_deopt_dependent_code(true); site->set_pretenure_decision(AllocationSite::kTenure); // Currently we just need to deopt when we make a state transition to // tenure. return true; } site->set_pretenure_decision(AllocationSite::kMaybeTenure); } else { site->set_pretenure_decision(AllocationSite::kDontTenure); } } return false; } inline bool DigestPretenuringFeedback(Isolate* isolate, AllocationSite* site, bool maximum_size_scavenge) { bool deopt = false; int create_count = site->memento_create_count(); int found_count = site->memento_found_count(); bool minimum_mementos_created = create_count >= AllocationSite::kPretenureMinimumCreated; double ratio = minimum_mementos_created || FLAG_trace_pretenuring_statistics ? static_cast(found_count) / create_count : 0.0; AllocationSite::PretenureDecision current_decision = site->pretenure_decision(); if (minimum_mementos_created) { deopt = MakePretenureDecision(site, current_decision, ratio, maximum_size_scavenge); } if (FLAG_trace_pretenuring_statistics) { PrintIsolate(isolate, "pretenuring: AllocationSite(%p): (created, found, ratio) " "(%d, %d, %f) %s => %s\n", static_cast(site), create_count, found_count, ratio, site->PretenureDecisionName(current_decision), site->PretenureDecisionName(site->pretenure_decision())); } // Clear feedback calculation fields until the next gc. site->set_memento_found_count(0); site->set_memento_create_count(0); return deopt; } } // namespace void Heap::RemoveAllocationSitePretenuringFeedback(AllocationSite* site) { global_pretenuring_feedback_.erase(site); } bool Heap::DeoptMaybeTenuredAllocationSites() { return new_space_->IsAtMaximumCapacity() && maximum_size_scavenges_ == 0; } void Heap::ProcessPretenuringFeedback() { bool trigger_deoptimization = false; if (FLAG_allocation_site_pretenuring) { int tenure_decisions = 0; int dont_tenure_decisions = 0; int allocation_mementos_found = 0; int allocation_sites = 0; int active_allocation_sites = 0; AllocationSite* site = nullptr; // Step 1: Digest feedback for recorded allocation sites. bool maximum_size_scavenge = MaximumSizeScavenge(); for (auto& site_and_count : global_pretenuring_feedback_) { allocation_sites++; site = site_and_count.first; // Count is always access through the site. DCHECK_EQ(0, site_and_count.second); int found_count = site->memento_found_count(); // An entry in the storage does not imply that the count is > 0 because // allocation sites might have been reset due to too many objects dying // in old space. if (found_count > 0) { DCHECK(site->IsAllocationSite()); active_allocation_sites++; allocation_mementos_found += found_count; if (DigestPretenuringFeedback(isolate_, site, maximum_size_scavenge)) { trigger_deoptimization = true; } if (site->GetPretenureMode() == TENURED) { tenure_decisions++; } else { dont_tenure_decisions++; } } } // Step 2: Deopt maybe tenured allocation sites if necessary. bool deopt_maybe_tenured = DeoptMaybeTenuredAllocationSites(); if (deopt_maybe_tenured) { ForeachAllocationSite( allocation_sites_list(), [&allocation_sites, &trigger_deoptimization](AllocationSite* site) { DCHECK(site->IsAllocationSite()); allocation_sites++; if (site->IsMaybeTenure()) { site->set_deopt_dependent_code(true); trigger_deoptimization = true; } }); } if (trigger_deoptimization) { isolate_->stack_guard()->RequestDeoptMarkedAllocationSites(); } if (FLAG_trace_pretenuring_statistics && (allocation_mementos_found > 0 || tenure_decisions > 0 || dont_tenure_decisions > 0)) { PrintIsolate(isolate(), "pretenuring: deopt_maybe_tenured=%d visited_sites=%d " "active_sites=%d " "mementos=%d tenured=%d not_tenured=%d\n", deopt_maybe_tenured ? 1 : 0, allocation_sites, active_allocation_sites, allocation_mementos_found, tenure_decisions, dont_tenure_decisions); } global_pretenuring_feedback_.clear(); global_pretenuring_feedback_.reserve(kInitialFeedbackCapacity); } } void Heap::InvalidateCodeEmbeddedObjects(Code* code) { MemoryChunk* chunk = MemoryChunk::FromAddress(code->address()); CodePageMemoryModificationScope modification_scope(chunk); code->InvalidateEmbeddedObjects(this); } void Heap::InvalidateCodeDeoptimizationData(Code* code) { MemoryChunk* chunk = MemoryChunk::FromAddress(code->address()); CodePageMemoryModificationScope modification_scope(chunk); code->set_deoptimization_data(ReadOnlyRoots(this).empty_fixed_array()); } void Heap::DeoptMarkedAllocationSites() { // TODO(hpayer): If iterating over the allocation sites list becomes a // performance issue, use a cache data structure in heap instead. ForeachAllocationSite(allocation_sites_list(), [this](AllocationSite* site) { if (site->deopt_dependent_code()) { site->dependent_code()->MarkCodeForDeoptimization( isolate_, DependentCode::kAllocationSiteTenuringChangedGroup); site->set_deopt_dependent_code(false); } }); Deoptimizer::DeoptimizeMarkedCode(isolate_); } void Heap::GarbageCollectionEpilogue() { TRACE_GC(tracer(), GCTracer::Scope::HEAP_EPILOGUE); if (Heap::ShouldZapGarbage() || FLAG_clear_free_memory) { ZapFromSpace(); } #ifdef VERIFY_HEAP if (FLAG_verify_heap) { Verify(); } #endif AllowHeapAllocation for_the_rest_of_the_epilogue; #ifdef DEBUG if (FLAG_print_global_handles) isolate_->global_handles()->Print(); if (FLAG_print_handles) PrintHandles(); if (FLAG_gc_verbose) Print(); if (FLAG_code_stats) ReportCodeStatistics("After GC"); if (FLAG_check_handle_count) CheckHandleCount(); #endif UpdateMaximumCommitted(); isolate_->counters()->alive_after_last_gc()->Set( static_cast(SizeOfObjects())); isolate_->counters()->string_table_capacity()->Set( string_table()->Capacity()); isolate_->counters()->number_of_symbols()->Set( string_table()->NumberOfElements()); if (CommittedMemory() > 0) { isolate_->counters()->external_fragmentation_total()->AddSample( static_cast(100 - (SizeOfObjects() * 100.0) / CommittedMemory())); isolate_->counters()->heap_sample_total_committed()->AddSample( static_cast(CommittedMemory() / KB)); isolate_->counters()->heap_sample_total_used()->AddSample( static_cast(SizeOfObjects() / KB)); isolate_->counters()->heap_sample_map_space_committed()->AddSample( static_cast(map_space()->CommittedMemory() / KB)); isolate_->counters()->heap_sample_code_space_committed()->AddSample( static_cast(code_space()->CommittedMemory() / KB)); isolate_->counters()->heap_sample_maximum_committed()->AddSample( static_cast(MaximumCommittedMemory() / KB)); } #define UPDATE_COUNTERS_FOR_SPACE(space) \ isolate_->counters()->space##_bytes_available()->Set( \ static_cast(space()->Available())); \ isolate_->counters()->space##_bytes_committed()->Set( \ static_cast(space()->CommittedMemory())); \ isolate_->counters()->space##_bytes_used()->Set( \ static_cast(space()->SizeOfObjects())); #define UPDATE_FRAGMENTATION_FOR_SPACE(space) \ if (space()->CommittedMemory() > 0) { \ isolate_->counters()->external_fragmentation_##space()->AddSample( \ static_cast(100 - \ (space()->SizeOfObjects() * 100.0) / \ space()->CommittedMemory())); \ } #define UPDATE_COUNTERS_AND_FRAGMENTATION_FOR_SPACE(space) \ UPDATE_COUNTERS_FOR_SPACE(space) \ UPDATE_FRAGMENTATION_FOR_SPACE(space) UPDATE_COUNTERS_FOR_SPACE(new_space) UPDATE_COUNTERS_AND_FRAGMENTATION_FOR_SPACE(old_space) UPDATE_COUNTERS_AND_FRAGMENTATION_FOR_SPACE(code_space) UPDATE_COUNTERS_AND_FRAGMENTATION_FOR_SPACE(map_space) UPDATE_COUNTERS_AND_FRAGMENTATION_FOR_SPACE(lo_space) #undef UPDATE_COUNTERS_FOR_SPACE #undef UPDATE_FRAGMENTATION_FOR_SPACE #undef UPDATE_COUNTERS_AND_FRAGMENTATION_FOR_SPACE #ifdef DEBUG ReportStatisticsAfterGC(); #endif // DEBUG last_gc_time_ = MonotonicallyIncreasingTimeInMs(); { TRACE_GC(tracer(), GCTracer::Scope::HEAP_EPILOGUE_REDUCE_NEW_SPACE); ReduceNewSpaceSize(); } } class GCCallbacksScope { public: explicit GCCallbacksScope(Heap* heap) : heap_(heap) { heap_->gc_callbacks_depth_++; } ~GCCallbacksScope() { heap_->gc_callbacks_depth_--; } bool CheckReenter() { return heap_->gc_callbacks_depth_ == 1; } private: Heap* heap_; }; void Heap::HandleGCRequest() { if (FLAG_stress_scavenge > 0 && stress_scavenge_observer_->HasRequestedGC()) { CollectAllGarbage(NEW_SPACE, GarbageCollectionReason::kTesting); stress_scavenge_observer_->RequestedGCDone(); } else if (HighMemoryPressure()) { incremental_marking()->reset_request_type(); CheckMemoryPressure(); } else if (incremental_marking()->request_type() == IncrementalMarking::COMPLETE_MARKING) { incremental_marking()->reset_request_type(); CollectAllGarbage(current_gc_flags_, GarbageCollectionReason::kFinalizeMarkingViaStackGuard, current_gc_callback_flags_); } else if (incremental_marking()->request_type() == IncrementalMarking::FINALIZATION && incremental_marking()->IsMarking() && !incremental_marking()->finalize_marking_completed()) { incremental_marking()->reset_request_type(); FinalizeIncrementalMarkingIncrementally( GarbageCollectionReason::kFinalizeMarkingViaStackGuard); } } void Heap::ScheduleIdleScavengeIfNeeded(int bytes_allocated) { scavenge_job_->ScheduleIdleTaskIfNeeded(this, bytes_allocated); } HistogramTimer* Heap::GCTypePriorityTimer(GarbageCollector collector) { if (IsYoungGenerationCollector(collector)) { if (isolate_->IsIsolateInBackground()) { return isolate_->counters()->gc_scavenger_background(); } return isolate_->counters()->gc_scavenger_foreground(); } else { if (!incremental_marking()->IsStopped()) { if (ShouldReduceMemory()) { if (isolate_->IsIsolateInBackground()) { return isolate_->counters()->gc_finalize_reduce_memory_background(); } return isolate_->counters()->gc_finalize_reduce_memory_foreground(); } else { if (isolate_->IsIsolateInBackground()) { return isolate_->counters()->gc_finalize_background(); } return isolate_->counters()->gc_finalize_foreground(); } } else { if (isolate_->IsIsolateInBackground()) { return isolate_->counters()->gc_compactor_background(); } return isolate_->counters()->gc_compactor_foreground(); } } } HistogramTimer* Heap::GCTypeTimer(GarbageCollector collector) { if (IsYoungGenerationCollector(collector)) { return isolate_->counters()->gc_scavenger(); } else { if (!incremental_marking()->IsStopped()) { if (ShouldReduceMemory()) { return isolate_->counters()->gc_finalize_reduce_memory(); } else { return isolate_->counters()->gc_finalize(); } } else { return isolate_->counters()->gc_compactor(); } } } void Heap::CollectAllGarbage(int flags, GarbageCollectionReason gc_reason, const v8::GCCallbackFlags gc_callback_flags) { // Since we are ignoring the return value, the exact choice of space does // not matter, so long as we do not specify NEW_SPACE, which would not // cause a full GC. set_current_gc_flags(flags); CollectGarbage(OLD_SPACE, gc_reason, gc_callback_flags); set_current_gc_flags(kNoGCFlags); } namespace { intptr_t CompareWords(int size, HeapObject* a, HeapObject* b) { int words = size / kPointerSize; DCHECK_EQ(a->Size(), size); DCHECK_EQ(b->Size(), size); intptr_t* slot_a = reinterpret_cast(a->address()); intptr_t* slot_b = reinterpret_cast(b->address()); for (int i = 0; i < words; i++) { if (*slot_a != *slot_b) { return *slot_a - *slot_b; } slot_a++; slot_b++; } return 0; } void ReportDuplicates(int size, std::vector& objects) { if (objects.size() == 0) return; sort(objects.begin(), objects.end(), [size](HeapObject* a, HeapObject* b) { intptr_t c = CompareWords(size, a, b); if (c != 0) return c < 0; return a < b; }); std::vector> duplicates; HeapObject* current = objects[0]; int count = 1; for (size_t i = 1; i < objects.size(); i++) { if (CompareWords(size, current, objects[i]) == 0) { count++; } else { if (count > 1) { duplicates.push_back(std::make_pair(count - 1, current)); } count = 1; current = objects[i]; } } if (count > 1) { duplicates.push_back(std::make_pair(count - 1, current)); } int threshold = FLAG_trace_duplicate_threshold_kb * KB; sort(duplicates.begin(), duplicates.end()); for (auto it = duplicates.rbegin(); it != duplicates.rend(); ++it) { int duplicate_bytes = it->first * size; if (duplicate_bytes < threshold) break; PrintF("%d duplicates of size %d each (%dKB)\n", it->first, size, duplicate_bytes / KB); PrintF("Sample object: "); it->second->Print(); PrintF("============================\n"); } } } // anonymous namespace void Heap::CollectAllAvailableGarbage(GarbageCollectionReason gc_reason) { // Since we are ignoring the return value, the exact choice of space does // not matter, so long as we do not specify NEW_SPACE, which would not // cause a full GC. // Major GC would invoke weak handle callbacks on weakly reachable // handles, but won't collect weakly reachable objects until next // major GC. Therefore if we collect aggressively and weak handle callback // has been invoked, we rerun major GC to release objects which become // garbage. // Note: as weak callbacks can execute arbitrary code, we cannot // hope that eventually there will be no weak callbacks invocations. // Therefore stop recollecting after several attempts. if (gc_reason == GarbageCollectionReason::kLastResort) { InvokeNearHeapLimitCallback(); } RuntimeCallTimerScope runtime_timer( isolate(), RuntimeCallCounterId::kGC_Custom_AllAvailableGarbage); // The optimizing compiler may be unnecessarily holding on to memory. isolate()->AbortConcurrentOptimization(BlockingBehavior::kDontBlock); isolate()->ClearSerializerData(); set_current_gc_flags(kReduceMemoryFootprintMask); isolate_->compilation_cache()->Clear(); const int kMaxNumberOfAttempts = 7; const int kMinNumberOfAttempts = 2; const v8::GCCallbackFlags callback_flags = gc_reason == GarbageCollectionReason::kLowMemoryNotification ? v8::kGCCallbackFlagForced : v8::kGCCallbackFlagCollectAllAvailableGarbage; for (int attempt = 0; attempt < kMaxNumberOfAttempts; attempt++) { if (!CollectGarbage(OLD_SPACE, gc_reason, callback_flags) && attempt + 1 >= kMinNumberOfAttempts) { break; } } set_current_gc_flags(kNoGCFlags); new_space_->Shrink(); UncommitFromSpace(); EagerlyFreeExternalMemory(); if (FLAG_trace_duplicate_threshold_kb) { std::map> objects_by_size; PagedSpaces spaces(this); for (PagedSpace* space = spaces.next(); space != nullptr; space = spaces.next()) { HeapObjectIterator it(space); for (HeapObject* obj = it.Next(); obj != nullptr; obj = it.Next()) { objects_by_size[obj->Size()].push_back(obj); } } { LargeObjectIterator it(lo_space()); for (HeapObject* obj = it.Next(); obj != nullptr; obj = it.Next()) { objects_by_size[obj->Size()].push_back(obj); } } for (auto it = objects_by_size.rbegin(); it != objects_by_size.rend(); ++it) { ReportDuplicates(it->first, it->second); } } } void Heap::PreciseCollectAllGarbage(int flags, GarbageCollectionReason gc_reason, const GCCallbackFlags gc_callback_flags) { if (!incremental_marking()->IsStopped()) { FinalizeIncrementalMarkingAtomically(gc_reason); } CollectAllGarbage(flags, gc_reason, gc_callback_flags); } void Heap::ReportExternalMemoryPressure() { const GCCallbackFlags kGCCallbackFlagsForExternalMemory = static_cast( kGCCallbackFlagSynchronousPhantomCallbackProcessing | kGCCallbackFlagCollectAllExternalMemory); if (external_memory_ > (external_memory_at_last_mark_compact_ + external_memory_hard_limit())) { CollectAllGarbage( kReduceMemoryFootprintMask, GarbageCollectionReason::kExternalMemoryPressure, static_cast(kGCCallbackFlagCollectAllAvailableGarbage | kGCCallbackFlagsForExternalMemory)); return; } if (incremental_marking()->IsStopped()) { if (incremental_marking()->CanBeActivated()) { StartIncrementalMarking(GCFlagsForIncrementalMarking(), GarbageCollectionReason::kExternalMemoryPressure, kGCCallbackFlagsForExternalMemory); } else { CollectAllGarbage(i::Heap::kNoGCFlags, GarbageCollectionReason::kExternalMemoryPressure, kGCCallbackFlagsForExternalMemory); } } else { // Incremental marking is turned on an has already been started. const double kMinStepSize = 5; const double kMaxStepSize = 10; const double ms_step = Min(kMaxStepSize, Max(kMinStepSize, static_cast(external_memory_) / external_memory_limit_ * kMinStepSize)); const double deadline = MonotonicallyIncreasingTimeInMs() + ms_step; // Extend the gc callback flags with external memory flags. current_gc_callback_flags_ = static_cast( current_gc_callback_flags_ | kGCCallbackFlagsForExternalMemory); incremental_marking()->AdvanceIncrementalMarking( deadline, IncrementalMarking::GC_VIA_STACK_GUARD, StepOrigin::kV8); } } void Heap::EnsureFillerObjectAtTop() { // There may be an allocation memento behind objects in new space. Upon // evacuation of a non-full new space (or if we are on the last page) there // may be uninitialized memory behind top. We fill the remainder of the page // with a filler. Address to_top = new_space_->top(); Page* page = Page::FromAddress(to_top - kPointerSize); if (page->Contains(to_top)) { int remaining_in_page = static_cast(page->area_end() - to_top); CreateFillerObjectAt(to_top, remaining_in_page, ClearRecordedSlots::kNo); } } bool Heap::CollectGarbage(AllocationSpace space, GarbageCollectionReason gc_reason, const v8::GCCallbackFlags gc_callback_flags) { const char* collector_reason = nullptr; GarbageCollector collector = SelectGarbageCollector(space, &collector_reason); if (!CanExpandOldGeneration(new_space()->Capacity())) { InvokeNearHeapLimitCallback(); } // Ensure that all pending phantom callbacks are invoked. isolate()->global_handles()->InvokeSecondPassPhantomCallbacks(); // The VM is in the GC state until exiting this function. VMState state(isolate()); #ifdef V8_ENABLE_ALLOCATION_TIMEOUT // Reset the allocation timeout, but make sure to allow at least a few // allocations after a collection. The reason for this is that we have a lot // of allocation sequences and we assume that a garbage collection will allow // the subsequent allocation attempts to go through. if (FLAG_random_gc_interval > 0 || FLAG_gc_interval >= 0) { allocation_timeout_ = Max(6, NextAllocationTimeout(allocation_timeout_)); } #endif EnsureFillerObjectAtTop(); if (IsYoungGenerationCollector(collector) && !incremental_marking()->IsStopped()) { if (FLAG_trace_incremental_marking) { isolate()->PrintWithTimestamp( "[IncrementalMarking] Scavenge during marking.\n"); } } bool next_gc_likely_to_collect_more = false; size_t committed_memory_before = 0; if (collector == MARK_COMPACTOR) { committed_memory_before = CommittedOldGenerationMemory(); } { tracer()->Start(collector, gc_reason, collector_reason); DCHECK(AllowHeapAllocation::IsAllowed()); DisallowHeapAllocation no_allocation_during_gc; GarbageCollectionPrologue(); { HistogramTimer* gc_type_timer = GCTypeTimer(collector); HistogramTimerScope histogram_timer_scope(gc_type_timer); TRACE_EVENT0("v8", gc_type_timer->name()); HistogramTimer* gc_type_priority_timer = GCTypePriorityTimer(collector); OptionalHistogramTimerScopeMode mode = isolate_->IsMemorySavingsModeActive() ? OptionalHistogramTimerScopeMode::DONT_TAKE_TIME : OptionalHistogramTimerScopeMode::TAKE_TIME; OptionalHistogramTimerScope histogram_timer_priority_scope( gc_type_priority_timer, mode); next_gc_likely_to_collect_more = PerformGarbageCollection(collector, gc_callback_flags); if (collector == MARK_COMPACTOR || collector == SCAVENGER) { tracer()->RecordGCPhasesHistograms(gc_type_timer); } } GarbageCollectionEpilogue(); if (collector == MARK_COMPACTOR && FLAG_track_detached_contexts) { isolate()->CheckDetachedContextsAfterGC(); } if (collector == MARK_COMPACTOR) { size_t committed_memory_after = CommittedOldGenerationMemory(); size_t used_memory_after = OldGenerationSizeOfObjects(); MemoryReducer::Event event; event.type = MemoryReducer::kMarkCompact; event.time_ms = MonotonicallyIncreasingTimeInMs(); // Trigger one more GC if // - this GC decreased committed memory, // - there is high fragmentation, // - there are live detached contexts. event.next_gc_likely_to_collect_more = (committed_memory_before > committed_memory_after + MB) || HasHighFragmentation(used_memory_after, committed_memory_after) || (detached_contexts()->length() > 0); event.committed_memory = committed_memory_after; if (deserialization_complete_) { memory_reducer_->NotifyMarkCompact(event); } } tracer()->Stop(collector); } if (collector == MARK_COMPACTOR && (gc_callback_flags & (kGCCallbackFlagForced | kGCCallbackFlagCollectAllAvailableGarbage)) != 0) { isolate()->CountUsage(v8::Isolate::kForcedGC); } // Start incremental marking for the next cycle. We do this only for scavenger // to avoid a loop where mark-compact causes another mark-compact. if (IsYoungGenerationCollector(collector)) { StartIncrementalMarkingIfAllocationLimitIsReached( GCFlagsForIncrementalMarking(), kGCCallbackScheduleIdleGarbageCollection); } return next_gc_likely_to_collect_more; } int Heap::NotifyContextDisposed(bool dependant_context) { if (!dependant_context) { tracer()->ResetSurvivalEvents(); old_generation_size_configured_ = false; MemoryReducer::Event event; event.type = MemoryReducer::kPossibleGarbage; event.time_ms = MonotonicallyIncreasingTimeInMs(); memory_reducer_->NotifyPossibleGarbage(event); } isolate()->AbortConcurrentOptimization(BlockingBehavior::kDontBlock); number_of_disposed_maps_ = retained_maps()->length(); tracer()->AddContextDisposalTime(MonotonicallyIncreasingTimeInMs()); return ++contexts_disposed_; } void Heap::StartIncrementalMarking(int gc_flags, GarbageCollectionReason gc_reason, GCCallbackFlags gc_callback_flags) { DCHECK(incremental_marking()->IsStopped()); set_current_gc_flags(gc_flags); current_gc_callback_flags_ = gc_callback_flags; incremental_marking()->Start(gc_reason); } void Heap::StartIncrementalMarkingIfAllocationLimitIsReached( int gc_flags, const GCCallbackFlags gc_callback_flags) { if (incremental_marking()->IsStopped()) { IncrementalMarkingLimit reached_limit = IncrementalMarkingLimitReached(); if (reached_limit == IncrementalMarkingLimit::kSoftLimit) { incremental_marking()->incremental_marking_job()->ScheduleTask(this); } else if (reached_limit == IncrementalMarkingLimit::kHardLimit) { StartIncrementalMarking(gc_flags, GarbageCollectionReason::kAllocationLimit, gc_callback_flags); } } } void Heap::StartIdleIncrementalMarking( GarbageCollectionReason gc_reason, const GCCallbackFlags gc_callback_flags) { gc_idle_time_handler_->ResetNoProgressCounter(); StartIncrementalMarking(kReduceMemoryFootprintMask, gc_reason, gc_callback_flags); } void Heap::MoveElements(FixedArray* array, int dst_index, int src_index, int len, WriteBarrierMode mode) { if (len == 0) return; DCHECK(array->map() != ReadOnlyRoots(this).fixed_cow_array_map()); Object** dst = array->data_start() + dst_index; Object** src = array->data_start() + src_index; if (FLAG_concurrent_marking && incremental_marking()->IsMarking()) { if (dst < src) { for (int i = 0; i < len; i++) { base::AsAtomicPointer::Relaxed_Store( dst + i, base::AsAtomicPointer::Relaxed_Load(src + i)); } } else { for (int i = len - 1; i >= 0; i--) { base::AsAtomicPointer::Relaxed_Store( dst + i, base::AsAtomicPointer::Relaxed_Load(src + i)); } } } else { MemMove(dst, src, len * kPointerSize); } if (mode == SKIP_WRITE_BARRIER) return; FIXED_ARRAY_ELEMENTS_WRITE_BARRIER(this, array, dst_index, len); } #ifdef VERIFY_HEAP // Helper class for verifying the string table. class StringTableVerifier : public ObjectVisitor { public: explicit StringTableVerifier(Isolate* isolate) : isolate_(isolate) {} void VisitPointers(HeapObject* host, Object** start, Object** end) override { // Visit all HeapObject pointers in [start, end). for (Object** p = start; p < end; p++) { DCHECK(!HasWeakHeapObjectTag(*p)); if ((*p)->IsHeapObject()) { HeapObject* object = HeapObject::cast(*p); // Check that the string is actually internalized. CHECK(object->IsTheHole(isolate_) || object->IsUndefined(isolate_) || object->IsInternalizedString()); } } } void VisitPointers(HeapObject* host, MaybeObject** start, MaybeObject** end) override { UNREACHABLE(); } private: Isolate* isolate_; }; static void VerifyStringTable(Isolate* isolate) { StringTableVerifier verifier(isolate); isolate->heap()->string_table()->IterateElements(&verifier); } #endif // VERIFY_HEAP bool Heap::ReserveSpace(Reservation* reservations, std::vector
* maps) { bool gc_performed = true; int counter = 0; static const int kThreshold = 20; while (gc_performed && counter++ < kThreshold) { gc_performed = false; for (int space = FIRST_SPACE; space < SerializerDeserializer::kNumberOfSpaces; space++) { Reservation* reservation = &reservations[space]; DCHECK_LE(1, reservation->size()); if (reservation->at(0).size == 0) { DCHECK_EQ(1, reservation->size()); continue; } bool perform_gc = false; if (space == MAP_SPACE) { // We allocate each map individually to avoid fragmentation. maps->clear(); DCHECK_LE(reservation->size(), 2); int reserved_size = 0; for (const Chunk& c : *reservation) reserved_size += c.size; DCHECK_EQ(0, reserved_size % Map::kSize); int num_maps = reserved_size / Map::kSize; for (int i = 0; i < num_maps; i++) { // The deserializer will update the skip list. AllocationResult allocation = map_space()->AllocateRawUnaligned( Map::kSize, PagedSpace::IGNORE_SKIP_LIST); HeapObject* free_space = nullptr; if (allocation.To(&free_space)) { // Mark with a free list node, in case we have a GC before // deserializing. Address free_space_address = free_space->address(); CreateFillerObjectAt(free_space_address, Map::kSize, ClearRecordedSlots::kNo); maps->push_back(free_space_address); } else { perform_gc = true; break; } } } else if (space == LO_SPACE) { // Just check that we can allocate during deserialization. DCHECK_LE(reservation->size(), 2); int reserved_size = 0; for (const Chunk& c : *reservation) reserved_size += c.size; perform_gc = !CanExpandOldGeneration(reserved_size); } else { for (auto& chunk : *reservation) { AllocationResult allocation; int size = chunk.size; DCHECK_LE(static_cast(size), MemoryAllocator::PageAreaSize( static_cast(space))); if (space == NEW_SPACE) { allocation = new_space()->AllocateRawUnaligned(size); } else { // The deserializer will update the skip list. allocation = paged_space(space)->AllocateRawUnaligned( size, PagedSpace::IGNORE_SKIP_LIST); } HeapObject* free_space = nullptr; if (allocation.To(&free_space)) { // Mark with a free list node, in case we have a GC before // deserializing. Address free_space_address = free_space->address(); CreateFillerObjectAt(free_space_address, size, ClearRecordedSlots::kNo); DCHECK_GT(SerializerDeserializer::kNumberOfPreallocatedSpaces, space); chunk.start = free_space_address; chunk.end = free_space_address + size; } else { perform_gc = true; break; } } } if (perform_gc) { // We cannot perfom a GC with an uninitialized isolate. This check // fails for example if the max old space size is chosen unwisely, // so that we cannot allocate space to deserialize the initial heap. if (!deserialization_complete_) { V8::FatalProcessOutOfMemory( isolate(), "insufficient memory to create an Isolate"); } if (space == NEW_SPACE) { CollectGarbage(NEW_SPACE, GarbageCollectionReason::kDeserializer); } else { if (counter > 1) { CollectAllGarbage(kReduceMemoryFootprintMask, GarbageCollectionReason::kDeserializer); } else { CollectAllGarbage(kNoGCFlags, GarbageCollectionReason::kDeserializer); } } gc_performed = true; break; // Abort for-loop over spaces and retry. } } } return !gc_performed; } void Heap::EnsureFromSpaceIsCommitted() { if (new_space_->CommitFromSpaceIfNeeded()) return; // Committing memory to from space failed. // Memory is exhausted and we will die. FatalProcessOutOfMemory("Committing semi space failed."); } void Heap::UpdateSurvivalStatistics(int start_new_space_size) { if (start_new_space_size == 0) return; promotion_ratio_ = (static_cast(promoted_objects_size_) / static_cast(start_new_space_size) * 100); if (previous_semi_space_copied_object_size_ > 0) { promotion_rate_ = (static_cast(promoted_objects_size_) / static_cast(previous_semi_space_copied_object_size_) * 100); } else { promotion_rate_ = 0; } semi_space_copied_rate_ = (static_cast(semi_space_copied_object_size_) / static_cast(start_new_space_size) * 100); double survival_rate = promotion_ratio_ + semi_space_copied_rate_; tracer()->AddSurvivalRatio(survival_rate); } bool Heap::PerformGarbageCollection( GarbageCollector collector, const v8::GCCallbackFlags gc_callback_flags) { int freed_global_handles = 0; if (!IsYoungGenerationCollector(collector)) { PROFILE(isolate_, CodeMovingGCEvent()); } #ifdef VERIFY_HEAP if (FLAG_verify_heap) { VerifyStringTable(this->isolate()); } #endif GCType gc_type = collector == MARK_COMPACTOR ? kGCTypeMarkSweepCompact : kGCTypeScavenge; { GCCallbacksScope scope(this); if (scope.CheckReenter()) { AllowHeapAllocation allow_allocation; TRACE_GC(tracer(), GCTracer::Scope::HEAP_EXTERNAL_PROLOGUE); VMState state(isolate_); HandleScope handle_scope(isolate_); CallGCPrologueCallbacks(gc_type, kNoGCCallbackFlags); } } EnsureFromSpaceIsCommitted(); size_t start_new_space_size = Heap::new_space()->Size(); { Heap::SkipStoreBufferScope skip_store_buffer_scope(store_buffer_); switch (collector) { case MARK_COMPACTOR: UpdateOldGenerationAllocationCounter(); // Perform mark-sweep with optional compaction. MarkCompact(); old_generation_size_configured_ = true; // This should be updated before PostGarbageCollectionProcessing, which // can cause another GC. Take into account the objects promoted during // GC. old_generation_allocation_counter_at_last_gc_ += static_cast(promoted_objects_size_); old_generation_size_at_last_gc_ = OldGenerationSizeOfObjects(); break; case MINOR_MARK_COMPACTOR: MinorMarkCompact(); break; case SCAVENGER: if ((fast_promotion_mode_ && CanExpandOldGeneration(new_space()->Size()))) { tracer()->NotifyYoungGenerationHandling( YoungGenerationHandling::kFastPromotionDuringScavenge); EvacuateYoungGeneration(); } else { tracer()->NotifyYoungGenerationHandling( YoungGenerationHandling::kRegularScavenge); Scavenge(); } break; } ProcessPretenuringFeedback(); } UpdateSurvivalStatistics(static_cast(start_new_space_size)); ConfigureInitialOldGenerationSize(); if (collector != MARK_COMPACTOR) { // Objects that died in the new space might have been accounted // as bytes marked ahead of schedule by the incremental marker. incremental_marking()->UpdateMarkedBytesAfterScavenge( start_new_space_size - SurvivedNewSpaceObjectSize()); } if (!fast_promotion_mode_ || collector == MARK_COMPACTOR) { ComputeFastPromotionMode(); } isolate_->counters()->objs_since_last_young()->Set(0); gc_post_processing_depth_++; { AllowHeapAllocation allow_allocation; TRACE_GC(tracer(), GCTracer::Scope::HEAP_EXTERNAL_WEAK_GLOBAL_HANDLES); freed_global_handles = isolate_->global_handles()->PostGarbageCollectionProcessing( collector, gc_callback_flags); } gc_post_processing_depth_--; isolate_->eternal_handles()->PostGarbageCollectionProcessing(); // Update relocatables. Relocatable::PostGarbageCollectionProcessing(isolate_); double gc_speed = tracer()->CombinedMarkCompactSpeedInBytesPerMillisecond(); double mutator_speed = tracer()->CurrentOldGenerationAllocationThroughputInBytesPerMillisecond(); size_t old_gen_size = OldGenerationSizeOfObjects(); if (collector == MARK_COMPACTOR) { // Register the amount of external allocated memory. external_memory_at_last_mark_compact_ = external_memory_; external_memory_limit_ = external_memory_ + kExternalAllocationSoftLimit; double max_factor = heap_controller()->MaxGrowingFactor(max_old_generation_size_); size_t new_limit = heap_controller()->CalculateAllocationLimit( old_gen_size, max_old_generation_size_, max_factor, gc_speed, mutator_speed, new_space()->Capacity(), CurrentHeapGrowingMode()); old_generation_allocation_limit_ = new_limit; CheckIneffectiveMarkCompact( old_gen_size, tracer()->AverageMarkCompactMutatorUtilization()); } else if (HasLowYoungGenerationAllocationRate() && old_generation_size_configured_) { double max_factor = heap_controller()->MaxGrowingFactor(max_old_generation_size_); size_t new_limit = heap_controller()->CalculateAllocationLimit( old_gen_size, max_old_generation_size_, max_factor, gc_speed, mutator_speed, new_space()->Capacity(), CurrentHeapGrowingMode()); if (new_limit < old_generation_allocation_limit_) { old_generation_allocation_limit_ = new_limit; } } { GCCallbacksScope scope(this); if (scope.CheckReenter()) { AllowHeapAllocation allow_allocation; TRACE_GC(tracer(), GCTracer::Scope::HEAP_EXTERNAL_EPILOGUE); VMState state(isolate_); HandleScope handle_scope(isolate_); CallGCEpilogueCallbacks(gc_type, gc_callback_flags); } } #ifdef VERIFY_HEAP if (FLAG_verify_heap) { VerifyStringTable(this->isolate()); } #endif return freed_global_handles > 0; } void Heap::CallGCPrologueCallbacks(GCType gc_type, GCCallbackFlags flags) { RuntimeCallTimerScope runtime_timer( isolate(), RuntimeCallCounterId::kGCPrologueCallback); for (const GCCallbackTuple& info : gc_prologue_callbacks_) { if (gc_type & info.gc_type) { v8::Isolate* isolate = reinterpret_cast(this->isolate()); info.callback(isolate, gc_type, flags, info.data); } } } void Heap::CallGCEpilogueCallbacks(GCType gc_type, GCCallbackFlags flags) { RuntimeCallTimerScope runtime_timer( isolate(), RuntimeCallCounterId::kGCEpilogueCallback); for (const GCCallbackTuple& info : gc_epilogue_callbacks_) { if (gc_type & info.gc_type) { v8::Isolate* isolate = reinterpret_cast(this->isolate()); info.callback(isolate, gc_type, flags, info.data); } } } void Heap::MarkCompact() { PauseAllocationObserversScope pause_observers(this); SetGCState(MARK_COMPACT); LOG(isolate_, ResourceEvent("markcompact", "begin")); uint64_t size_of_objects_before_gc = SizeOfObjects(); CodeSpaceMemoryModificationScope code_modifcation(this); mark_compact_collector()->Prepare(); ms_count_++; MarkCompactPrologue(); mark_compact_collector()->CollectGarbage(); LOG(isolate_, ResourceEvent("markcompact", "end")); MarkCompactEpilogue(); if (FLAG_allocation_site_pretenuring) { EvaluateOldSpaceLocalPretenuring(size_of_objects_before_gc); } } void Heap::MinorMarkCompact() { #ifdef ENABLE_MINOR_MC DCHECK(FLAG_minor_mc); PauseAllocationObserversScope pause_observers(this); SetGCState(MINOR_MARK_COMPACT); LOG(isolate_, ResourceEvent("MinorMarkCompact", "begin")); TRACE_GC(tracer(), GCTracer::Scope::MINOR_MC); AlwaysAllocateScope always_allocate(isolate()); IncrementalMarking::PauseBlackAllocationScope pause_black_allocation( incremental_marking()); ConcurrentMarking::PauseScope pause_scope(concurrent_marking()); minor_mark_compact_collector()->CollectGarbage(); LOG(isolate_, ResourceEvent("MinorMarkCompact", "end")); SetGCState(NOT_IN_GC); #else UNREACHABLE(); #endif // ENABLE_MINOR_MC } void Heap::MarkCompactEpilogue() { TRACE_GC(tracer(), GCTracer::Scope::MC_EPILOGUE); SetGCState(NOT_IN_GC); isolate_->counters()->objs_since_last_full()->Set(0); incremental_marking()->Epilogue(); DCHECK(incremental_marking()->IsStopped()); } void Heap::MarkCompactPrologue() { TRACE_GC(tracer(), GCTracer::Scope::MC_PROLOGUE); isolate_->context_slot_cache()->Clear(); isolate_->descriptor_lookup_cache()->Clear(); RegExpResultsCache::Clear(string_split_cache()); RegExpResultsCache::Clear(regexp_multiple_cache()); isolate_->compilation_cache()->MarkCompactPrologue(); FlushNumberStringCache(); } void Heap::CheckNewSpaceExpansionCriteria() { if (FLAG_experimental_new_space_growth_heuristic) { if (new_space_->TotalCapacity() < new_space_->MaximumCapacity() && survived_last_scavenge_ * 100 / new_space_->TotalCapacity() >= 10) { // Grow the size of new space if there is room to grow, and more than 10% // have survived the last scavenge. new_space_->Grow(); survived_since_last_expansion_ = 0; } } else if (new_space_->TotalCapacity() < new_space_->MaximumCapacity() && survived_since_last_expansion_ > new_space_->TotalCapacity()) { // Grow the size of new space if there is room to grow, and enough data // has survived scavenge since the last expansion. new_space_->Grow(); survived_since_last_expansion_ = 0; } } void Heap::EvacuateYoungGeneration() { TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_FAST_PROMOTE); base::LockGuard guard(relocation_mutex()); ConcurrentMarking::PauseScope pause_scope(concurrent_marking()); if (!FLAG_concurrent_marking) { DCHECK(fast_promotion_mode_); DCHECK(CanExpandOldGeneration(new_space()->Size())); } mark_compact_collector()->sweeper()->EnsureIterabilityCompleted(); SetGCState(SCAVENGE); LOG(isolate_, ResourceEvent("scavenge", "begin")); // Move pages from new->old generation. PageRange range(new_space()->first_allocatable_address(), new_space()->top()); for (auto it = range.begin(); it != range.end();) { Page* p = (*++it)->prev_page(); new_space()->from_space().RemovePage(p); Page::ConvertNewToOld(p); if (incremental_marking()->IsMarking()) mark_compact_collector()->RecordLiveSlotsOnPage(p); } // Reset new space. if (!new_space()->Rebalance()) { FatalProcessOutOfMemory("NewSpace::Rebalance"); } new_space()->ResetLinearAllocationArea(); new_space()->set_age_mark(new_space()->top()); // Fix up special trackers. external_string_table_.PromoteAllNewSpaceStrings(); // GlobalHandles are updated in PostGarbageCollectonProcessing IncrementYoungSurvivorsCounter(new_space()->Size()); IncrementPromotedObjectsSize(new_space()->Size()); IncrementSemiSpaceCopiedObjectSize(0); LOG(isolate_, ResourceEvent("scavenge", "end")); SetGCState(NOT_IN_GC); } void Heap::Scavenge() { TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_SCAVENGE); base::LockGuard guard(relocation_mutex()); ConcurrentMarking::PauseScope pause_scope(concurrent_marking()); // There are soft limits in the allocation code, designed to trigger a mark // sweep collection by failing allocations. There is no sense in trying to // trigger one during scavenge: scavenges allocation should always succeed. AlwaysAllocateScope scope(isolate()); // Bump-pointer allocations done during scavenge are not real allocations. // Pause the inline allocation steps. PauseAllocationObserversScope pause_observers(this); IncrementalMarking::PauseBlackAllocationScope pause_black_allocation( incremental_marking()); mark_compact_collector()->sweeper()->EnsureIterabilityCompleted(); SetGCState(SCAVENGE); // Flip the semispaces. After flipping, to space is empty, from space has // live objects. new_space()->Flip(); new_space()->ResetLinearAllocationArea(); // We also flip the young generation large object space. All large objects // will be in the from space. new_lo_space()->Flip(); // Implements Cheney's copying algorithm LOG(isolate_, ResourceEvent("scavenge", "begin")); scavenger_collector_->CollectGarbage(); LOG(isolate_, ResourceEvent("scavenge", "end")); SetGCState(NOT_IN_GC); } void Heap::ComputeFastPromotionMode() { const size_t survived_in_new_space = survived_last_scavenge_ * 100 / new_space_->Capacity(); fast_promotion_mode_ = !FLAG_optimize_for_size && FLAG_fast_promotion_new_space && !ShouldReduceMemory() && new_space_->IsAtMaximumCapacity() && survived_in_new_space >= kMinPromotedPercentForFastPromotionMode; if (FLAG_trace_gc_verbose && !FLAG_trace_gc_ignore_scavenger) { PrintIsolate( isolate(), "Fast promotion mode: %s survival rate: %" PRIuS "%%\n", fast_promotion_mode_ ? "true" : "false", survived_in_new_space); } } void Heap::UnprotectAndRegisterMemoryChunk(MemoryChunk* chunk) { if (unprotected_memory_chunks_registry_enabled_) { base::LockGuard guard(&unprotected_memory_chunks_mutex_); if (unprotected_memory_chunks_.insert(chunk).second) { chunk->SetReadAndWritable(); } } } void Heap::UnprotectAndRegisterMemoryChunk(HeapObject* object) { UnprotectAndRegisterMemoryChunk(MemoryChunk::FromAddress(object->address())); } void Heap::UnregisterUnprotectedMemoryChunk(MemoryChunk* chunk) { unprotected_memory_chunks_.erase(chunk); } void Heap::ProtectUnprotectedMemoryChunks() { DCHECK(unprotected_memory_chunks_registry_enabled_); for (auto chunk = unprotected_memory_chunks_.begin(); chunk != unprotected_memory_chunks_.end(); chunk++) { CHECK(memory_allocator()->IsMemoryChunkExecutable(*chunk)); (*chunk)->SetReadAndExecutable(); } unprotected_memory_chunks_.clear(); } bool Heap::ExternalStringTable::Contains(HeapObject* obj) { for (size_t i = 0; i < new_space_strings_.size(); ++i) { if (new_space_strings_[i] == obj) return true; } for (size_t i = 0; i < old_space_strings_.size(); ++i) { if (old_space_strings_[i] == obj) return true; } return false; } String* Heap::UpdateNewSpaceReferenceInExternalStringTableEntry(Heap* heap, Object** p) { MapWord first_word = HeapObject::cast(*p)->map_word(); if (!first_word.IsForwardingAddress()) { // Unreachable external string can be finalized. String* string = String::cast(*p); if (!string->IsExternalString()) { // Original external string has been internalized. DCHECK(string->IsThinString()); return nullptr; } heap->FinalizeExternalString(string); return nullptr; } // String is still reachable. String* new_string = String::cast(first_word.ToForwardingAddress()); if (new_string->IsThinString()) { // Filtering Thin strings out of the external string table. return nullptr; } else if (new_string->IsExternalString()) { MemoryChunk::MoveExternalBackingStoreBytes( ExternalBackingStoreType::kExternalString, Page::FromAddress(reinterpret_cast
(*p)), Page::FromHeapObject(new_string), ExternalString::cast(new_string)->ExternalPayloadSize()); return new_string; } // Internalization can replace external strings with non-external strings. return new_string->IsExternalString() ? new_string : nullptr; } void Heap::ExternalStringTable::VerifyNewSpace() { #ifdef DEBUG std::set visited_map; std::map size_map; ExternalBackingStoreType type = ExternalBackingStoreType::kExternalString; for (size_t i = 0; i < new_space_strings_.size(); ++i) { String* obj = String::cast(new_space_strings_[i]); MemoryChunk* mc = MemoryChunk::FromHeapObject(obj); DCHECK(mc->InNewSpace()); DCHECK(heap_->InNewSpace(obj)); DCHECK(!obj->IsTheHole(heap_->isolate())); DCHECK(obj->IsExternalString()); // Note: we can have repeated elements in the table. DCHECK_EQ(0, visited_map.count(obj)); visited_map.insert(obj); size_map[mc] += ExternalString::cast(obj)->ExternalPayloadSize(); } for (std::map::iterator it = size_map.begin(); it != size_map.end(); it++) DCHECK_EQ(it->first->ExternalBackingStoreBytes(type), it->second); #endif } void Heap::ExternalStringTable::Verify() { #ifdef DEBUG std::set visited_map; std::map size_map; ExternalBackingStoreType type = ExternalBackingStoreType::kExternalString; VerifyNewSpace(); for (size_t i = 0; i < old_space_strings_.size(); ++i) { String* obj = String::cast(old_space_strings_[i]); MemoryChunk* mc = MemoryChunk::FromHeapObject(obj); DCHECK(!mc->InNewSpace()); DCHECK(!heap_->InNewSpace(obj)); DCHECK(!obj->IsTheHole(heap_->isolate())); DCHECK(obj->IsExternalString()); // Note: we can have repeated elements in the table. DCHECK_EQ(0, visited_map.count(obj)); visited_map.insert(obj); size_map[mc] += ExternalString::cast(obj)->ExternalPayloadSize(); } for (std::map::iterator it = size_map.begin(); it != size_map.end(); it++) DCHECK_EQ(it->first->ExternalBackingStoreBytes(type), it->second); #endif } void Heap::ExternalStringTable::UpdateNewSpaceReferences( Heap::ExternalStringTableUpdaterCallback updater_func) { if (new_space_strings_.empty()) return; Object** start = new_space_strings_.data(); Object** end = start + new_space_strings_.size(); Object** last = start; for (Object** p = start; p < end; ++p) { String* target = updater_func(heap_, p); if (target == nullptr) continue; DCHECK(target->IsExternalString()); if (InNewSpace(target)) { // String is still in new space. Update the table entry. *last = target; ++last; } else { // String got promoted. Move it to the old string list. old_space_strings_.push_back(target); } } DCHECK_LE(last, end); new_space_strings_.resize(static_cast(last - start)); #ifdef VERIFY_HEAP if (FLAG_verify_heap) { VerifyNewSpace(); } #endif } void Heap::ExternalStringTable::PromoteAllNewSpaceStrings() { old_space_strings_.reserve(old_space_strings_.size() + new_space_strings_.size()); std::move(std::begin(new_space_strings_), std::end(new_space_strings_), std::back_inserter(old_space_strings_)); new_space_strings_.clear(); } void Heap::ExternalStringTable::IterateNewSpaceStrings(RootVisitor* v) { if (!new_space_strings_.empty()) { v->VisitRootPointers(Root::kExternalStringsTable, nullptr, new_space_strings_.data(), new_space_strings_.data() + new_space_strings_.size()); } } void Heap::ExternalStringTable::IterateAll(RootVisitor* v) { IterateNewSpaceStrings(v); if (!old_space_strings_.empty()) { v->VisitRootPointers(Root::kExternalStringsTable, nullptr, old_space_strings_.data(), old_space_strings_.data() + old_space_strings_.size()); } } void Heap::UpdateNewSpaceReferencesInExternalStringTable( ExternalStringTableUpdaterCallback updater_func) { external_string_table_.UpdateNewSpaceReferences(updater_func); } void Heap::ExternalStringTable::UpdateReferences( Heap::ExternalStringTableUpdaterCallback updater_func) { if (old_space_strings_.size() > 0) { Object** start = old_space_strings_.data(); Object** end = start + old_space_strings_.size(); for (Object** p = start; p < end; ++p) *p = updater_func(heap_, p); } UpdateNewSpaceReferences(updater_func); } void Heap::UpdateReferencesInExternalStringTable( ExternalStringTableUpdaterCallback updater_func) { external_string_table_.UpdateReferences(updater_func); } void Heap::ProcessAllWeakReferences(WeakObjectRetainer* retainer) { ProcessNativeContexts(retainer); ProcessAllocationSites(retainer); } void Heap::ProcessYoungWeakReferences(WeakObjectRetainer* retainer) { ProcessNativeContexts(retainer); } void Heap::ProcessNativeContexts(WeakObjectRetainer* retainer) { Object* head = VisitWeakList(this, native_contexts_list(), retainer); // Update the head of the list of contexts. set_native_contexts_list(head); } void Heap::ProcessAllocationSites(WeakObjectRetainer* retainer) { Object* allocation_site_obj = VisitWeakList(this, allocation_sites_list(), retainer); set_allocation_sites_list(allocation_site_obj); } void Heap::ProcessWeakListRoots(WeakObjectRetainer* retainer) { set_native_contexts_list(retainer->RetainAs(native_contexts_list())); set_allocation_sites_list(retainer->RetainAs(allocation_sites_list())); } void Heap::ForeachAllocationSite( Object* list, const std::function& visitor) { DisallowHeapAllocation disallow_heap_allocation; Object* current = list; while (current->IsAllocationSite()) { AllocationSite* site = AllocationSite::cast(current); visitor(site); Object* current_nested = site->nested_site(); while (current_nested->IsAllocationSite()) { AllocationSite* nested_site = AllocationSite::cast(current_nested); visitor(nested_site); current_nested = nested_site->nested_site(); } current = site->weak_next(); } } void Heap::ResetAllAllocationSitesDependentCode(PretenureFlag flag) { DisallowHeapAllocation no_allocation_scope; bool marked = false; ForeachAllocationSite(allocation_sites_list(), [&marked, flag, this](AllocationSite* site) { if (site->GetPretenureMode() == flag) { site->ResetPretenureDecision(); site->set_deopt_dependent_code(true); marked = true; RemoveAllocationSitePretenuringFeedback(site); return; } }); if (marked) isolate_->stack_guard()->RequestDeoptMarkedAllocationSites(); } void Heap::EvaluateOldSpaceLocalPretenuring( uint64_t size_of_objects_before_gc) { uint64_t size_of_objects_after_gc = SizeOfObjects(); double old_generation_survival_rate = (static_cast(size_of_objects_after_gc) * 100) / static_cast(size_of_objects_before_gc); if (old_generation_survival_rate < kOldSurvivalRateLowThreshold) { // Too many objects died in the old generation, pretenuring of wrong // allocation sites may be the cause for that. We have to deopt all // dependent code registered in the allocation sites to re-evaluate // our pretenuring decisions. ResetAllAllocationSitesDependentCode(TENURED); if (FLAG_trace_pretenuring) { PrintF( "Deopt all allocation sites dependent code due to low survival " "rate in the old generation %f\n", old_generation_survival_rate); } } } void Heap::VisitExternalResources(v8::ExternalResourceVisitor* visitor) { DisallowHeapAllocation no_allocation; // All external strings are listed in the external string table. class ExternalStringTableVisitorAdapter : public RootVisitor { public: explicit ExternalStringTableVisitorAdapter( Isolate* isolate, v8::ExternalResourceVisitor* visitor) : isolate_(isolate), visitor_(visitor) {} void VisitRootPointers(Root root, const char* description, Object** start, Object** end) override { for (Object** p = start; p < end; p++) { DCHECK((*p)->IsExternalString()); visitor_->VisitExternalString( Utils::ToLocal(Handle(String::cast(*p), isolate_))); } } private: Isolate* isolate_; v8::ExternalResourceVisitor* visitor_; } external_string_table_visitor(isolate(), visitor); external_string_table_.IterateAll(&external_string_table_visitor); } STATIC_ASSERT((FixedDoubleArray::kHeaderSize & kDoubleAlignmentMask) == 0); // NOLINT STATIC_ASSERT((FixedTypedArrayBase::kDataOffset & kDoubleAlignmentMask) == 0); // NOLINT #ifdef V8_HOST_ARCH_32_BIT STATIC_ASSERT((HeapNumber::kValueOffset & kDoubleAlignmentMask) != 0); // NOLINT #endif int Heap::GetMaximumFillToAlign(AllocationAlignment alignment) { switch (alignment) { case kWordAligned: return 0; case kDoubleAligned: case kDoubleUnaligned: return kDoubleSize - kPointerSize; default: UNREACHABLE(); } return 0; } int Heap::GetFillToAlign(Address address, AllocationAlignment alignment) { if (alignment == kDoubleAligned && (address & kDoubleAlignmentMask) != 0) return kPointerSize; if (alignment == kDoubleUnaligned && (address & kDoubleAlignmentMask) == 0) return kDoubleSize - kPointerSize; // No fill if double is always aligned. return 0; } HeapObject* Heap::PrecedeWithFiller(HeapObject* object, int filler_size) { CreateFillerObjectAt(object->address(), filler_size, ClearRecordedSlots::kNo); return HeapObject::FromAddress(object->address() + filler_size); } HeapObject* Heap::AlignWithFiller(HeapObject* object, int object_size, int allocation_size, AllocationAlignment alignment) { int filler_size = allocation_size - object_size; DCHECK_LT(0, filler_size); int pre_filler = GetFillToAlign(object->address(), alignment); if (pre_filler) { object = PrecedeWithFiller(object, pre_filler); filler_size -= pre_filler; } if (filler_size) CreateFillerObjectAt(object->address() + object_size, filler_size, ClearRecordedSlots::kNo); return object; } void Heap::RegisterNewArrayBuffer(JSArrayBuffer* buffer) { ArrayBufferTracker::RegisterNew(this, buffer); } void Heap::UnregisterArrayBuffer(JSArrayBuffer* buffer) { ArrayBufferTracker::Unregister(this, buffer); } void Heap::ConfigureInitialOldGenerationSize() { if (!old_generation_size_configured_ && tracer()->SurvivalEventsRecorded()) { old_generation_allocation_limit_ = Max(heap_controller()->MinimumAllocationLimitGrowingStep( CurrentHeapGrowingMode()), static_cast( static_cast(old_generation_allocation_limit_) * (tracer()->AverageSurvivalRatio() / 100))); } } void Heap::CreateJSEntryStub() { JSEntryStub stub(isolate(), StackFrame::ENTRY); set_js_entry_code(*stub.GetCode()); } void Heap::CreateJSConstructEntryStub() { JSEntryStub stub(isolate(), StackFrame::CONSTRUCT_ENTRY); set_js_construct_entry_code(*stub.GetCode()); } void Heap::CreateJSRunMicrotasksEntryStub() { JSEntryStub stub(isolate(), JSEntryStub::SpecialTarget::kRunMicrotasks); set_js_run_microtasks_entry_code(*stub.GetCode()); } void Heap::CreateFixedStubs() { // Here we create roots for fixed stubs. They are needed at GC // for cooking and uncooking (check out frames.cc). // The eliminates the need for doing dictionary lookup in the // stub cache for these stubs. HandleScope scope(isolate()); // Canonicalize handles, so that we can share constant pool entries pointing // to code targets without dereferencing their handles. CanonicalHandleScope canonical(isolate()); // Create stubs that should be there, so we don't unexpectedly have to // create them if we need them during the creation of another stub. // Stub creation mixes raw pointers and handles in an unsafe manner so // we cannot create stubs while we are creating stubs. CodeStub::GenerateStubsAheadOfTime(isolate()); // gcc-4.4 has problem generating correct code of following snippet: // { JSEntryStub stub; // js_entry_code_ = *stub.GetCode(); // } // { JSConstructEntryStub stub; // js_construct_entry_code_ = *stub.GetCode(); // } // To workaround the problem, make separate functions without inlining. Heap::CreateJSEntryStub(); Heap::CreateJSConstructEntryStub(); Heap::CreateJSRunMicrotasksEntryStub(); } bool Heap::RootCanBeWrittenAfterInitialization(RootIndex root_index) { switch (root_index) { case RootIndex::kNumberStringCache: case RootIndex::kCodeStubs: case RootIndex::kScriptList: case RootIndex::kMaterializedObjects: case RootIndex::kDetachedContexts: case RootIndex::kRetainedMaps: case RootIndex::kRetainingPathTargets: case RootIndex::kFeedbackVectorsForProfilingTools: case RootIndex::kNoScriptSharedFunctionInfos: case RootIndex::kSerializedObjects: case RootIndex::kSerializedGlobalProxySizes: case RootIndex::kPublicSymbolTable: case RootIndex::kApiSymbolTable: case RootIndex::kApiPrivateSymbolTable: case RootIndex::kMessageListeners: // Smi values #define SMI_ENTRY(type, name, Name) case RootIndex::k##Name: SMI_ROOT_LIST(SMI_ENTRY) #undef SMI_ENTRY // String table case RootIndex::kStringTable: return true; default: return false; } } bool Heap::RootCanBeTreatedAsConstant(RootIndex root_index) { bool can_be = !RootCanBeWrittenAfterInitialization(root_index) && !InNewSpace(root(root_index)); DCHECK_IMPLIES(can_be, IsImmovable(HeapObject::cast(root(root_index)))); return can_be; } void Heap::FlushNumberStringCache() { // Flush the number to string cache. int len = number_string_cache()->length(); for (int i = 0; i < len; i++) { number_string_cache()->set_undefined(i); } } HeapObject* Heap::CreateFillerObjectAt(Address addr, int size, ClearRecordedSlots clear_slots_mode, ClearFreedMemoryMode clear_memory_mode) { if (size == 0) return nullptr; HeapObject* filler = HeapObject::FromAddress(addr); if (size == kPointerSize) { filler->set_map_after_allocation( reinterpret_cast(root(RootIndex::kOnePointerFillerMap)), SKIP_WRITE_BARRIER); } else if (size == 2 * kPointerSize) { filler->set_map_after_allocation( reinterpret_cast(root(RootIndex::kTwoPointerFillerMap)), SKIP_WRITE_BARRIER); if (clear_memory_mode == ClearFreedMemoryMode::kClearFreedMemory) { Memory
(addr + kPointerSize) = static_cast
(kClearedFreeMemoryValue); } } else { DCHECK_GT(size, 2 * kPointerSize); filler->set_map_after_allocation( reinterpret_cast(root(RootIndex::kFreeSpaceMap)), SKIP_WRITE_BARRIER); FreeSpace::cast(filler)->relaxed_write_size(size); if (clear_memory_mode == ClearFreedMemoryMode::kClearFreedMemory) { memset(reinterpret_cast(addr + 2 * kPointerSize), kClearedFreeMemoryValue, size - 2 * kPointerSize); } } if (clear_slots_mode == ClearRecordedSlots::kYes) { ClearRecordedSlotRange(addr, addr + size); } // At this point, we may be deserializing the heap from a snapshot, and // none of the maps have been created yet and are nullptr. DCHECK((filler->map() == nullptr && !deserialization_complete_) || filler->map()->IsMap()); return filler; } bool Heap::CanMoveObjectStart(HeapObject* object) { if (!FLAG_move_object_start) return false; // Sampling heap profiler may have a reference to the object. if (isolate()->heap_profiler()->is_sampling_allocations()) return false; Address address = object->address(); if (lo_space()->Contains(object)) return false; // We can move the object start if the page was already swept. return Page::FromAddress(address)->SweepingDone(); } bool Heap::IsImmovable(HeapObject* object) { MemoryChunk* chunk = MemoryChunk::FromAddress(object->address()); return chunk->NeverEvacuate() || chunk->owner()->identity() == LO_SPACE; } #ifdef ENABLE_SLOW_DCHECKS namespace { class LeftTrimmerVerifierRootVisitor : public RootVisitor { public: explicit LeftTrimmerVerifierRootVisitor(FixedArrayBase* to_check) : to_check_(to_check) {} void VisitRootPointers(Root root, const char* description, Object** start, Object** end) override { for (Object** p = start; p < end; ++p) { DCHECK_NE(*p, to_check_); } } private: FixedArrayBase* to_check_; DISALLOW_COPY_AND_ASSIGN(LeftTrimmerVerifierRootVisitor); }; } // namespace #endif // ENABLE_SLOW_DCHECKS namespace { bool MayContainRecordedSlots(HeapObject* object) { // New space object do not have recorded slots. if (MemoryChunk::FromHeapObject(object)->InNewSpace()) return false; // Whitelist objects that definitely do not have pointers. if (object->IsByteArray() || object->IsFixedDoubleArray()) return false; // Conservatively return true for other objects. return true; } } // namespace FixedArrayBase* Heap::LeftTrimFixedArray(FixedArrayBase* object, int elements_to_trim) { if (elements_to_trim == 0) { // This simplifies reasoning in the rest of the function. return object; } CHECK_NOT_NULL(object); DCHECK(CanMoveObjectStart(object)); // Add custom visitor to concurrent marker if new left-trimmable type // is added. DCHECK(object->IsFixedArray() || object->IsFixedDoubleArray()); const int element_size = object->IsFixedArray() ? kPointerSize : kDoubleSize; const int bytes_to_trim = elements_to_trim * element_size; Map* map = object->map(); // For now this trick is only applied to objects in new and paged space. // In large object space the object's start must coincide with chunk // and thus the trick is just not applicable. DCHECK(!lo_space()->Contains(object)); DCHECK(object->map() != ReadOnlyRoots(this).fixed_cow_array_map()); STATIC_ASSERT(FixedArrayBase::kMapOffset == 0); STATIC_ASSERT(FixedArrayBase::kLengthOffset == kPointerSize); STATIC_ASSERT(FixedArrayBase::kHeaderSize == 2 * kPointerSize); const int len = object->length(); DCHECK(elements_to_trim <= len); // Calculate location of new array start. Address old_start = object->address(); Address new_start = old_start + bytes_to_trim; if (incremental_marking()->IsMarking()) { incremental_marking()->NotifyLeftTrimming( object, HeapObject::FromAddress(new_start)); } // Technically in new space this write might be omitted (except for // debug mode which iterates through the heap), but to play safer // we still do it. HeapObject* filler = CreateFillerObjectAt(old_start, bytes_to_trim, ClearRecordedSlots::kYes); // Initialize header of the trimmed array. Since left trimming is only // performed on pages which are not concurrently swept creating a filler // object does not require synchronization. RELAXED_WRITE_FIELD(object, bytes_to_trim, map); RELAXED_WRITE_FIELD(object, bytes_to_trim + kPointerSize, Smi::FromInt(len - elements_to_trim)); FixedArrayBase* new_object = FixedArrayBase::cast(HeapObject::FromAddress(new_start)); // Remove recorded slots for the new map and length offset. ClearRecordedSlot(new_object, HeapObject::RawField(new_object, 0)); ClearRecordedSlot(new_object, HeapObject::RawField( new_object, FixedArrayBase::kLengthOffset)); // Handle invalidated old-to-old slots. if (incremental_marking()->IsCompacting() && MayContainRecordedSlots(new_object)) { // If the array was right-trimmed before, then it is registered in // the invalidated_slots. MemoryChunk::FromHeapObject(new_object) ->MoveObjectWithInvalidatedSlots(filler, new_object); // We have to clear slots in the free space to avoid stale old-to-old slots. // Note we cannot use ClearFreedMemoryMode of CreateFillerObjectAt because // we need pointer granularity writes to avoid race with the concurrent // marking. if (filler->Size() > FreeSpace::kSize) { MemsetPointer(HeapObject::RawField(filler, FreeSpace::kSize), ReadOnlyRoots(this).undefined_value(), (filler->Size() - FreeSpace::kSize) / kPointerSize); } } // Notify the heap profiler of change in object layout. OnMoveEvent(new_object, object, new_object->Size()); #ifdef ENABLE_SLOW_DCHECKS if (FLAG_enable_slow_asserts) { // Make sure the stack or other roots (e.g., Handles) don't contain pointers // to the original FixedArray (which is now the filler object). LeftTrimmerVerifierRootVisitor root_visitor(object); IterateRoots(&root_visitor, VISIT_ALL); } #endif // ENABLE_SLOW_DCHECKS return new_object; } void Heap::RightTrimFixedArray(FixedArrayBase* object, int elements_to_trim) { const int len = object->length(); DCHECK_LE(elements_to_trim, len); DCHECK_GE(elements_to_trim, 0); int bytes_to_trim; DCHECK(!object->IsFixedTypedArrayBase()); if (object->IsByteArray()) { int new_size = ByteArray::SizeFor(len - elements_to_trim); bytes_to_trim = ByteArray::SizeFor(len) - new_size; DCHECK_GE(bytes_to_trim, 0); } else if (object->IsFixedArray()) { CHECK_NE(elements_to_trim, len); bytes_to_trim = elements_to_trim * kPointerSize; } else { DCHECK(object->IsFixedDoubleArray()); CHECK_NE(elements_to_trim, len); bytes_to_trim = elements_to_trim * kDoubleSize; } CreateFillerForArray(object, elements_to_trim, bytes_to_trim); } void Heap::RightTrimWeakFixedArray(WeakFixedArray* object, int elements_to_trim) { // This function is safe to use only at the end of the mark compact // collection: When marking, we record the weak slots, and shrinking // invalidates them. DCHECK_EQ(gc_state(), MARK_COMPACT); CreateFillerForArray(object, elements_to_trim, elements_to_trim * kPointerSize); } template void Heap::CreateFillerForArray(T* object, int elements_to_trim, int bytes_to_trim) { DCHECK(object->IsFixedArrayBase() || object->IsByteArray() || object->IsWeakFixedArray()); // For now this trick is only applied to objects in new and paged space. DCHECK(object->map() != ReadOnlyRoots(this).fixed_cow_array_map()); if (bytes_to_trim == 0) { DCHECK_EQ(elements_to_trim, 0); // No need to create filler and update live bytes counters. return; } // Calculate location of new array end. int old_size = object->Size(); Address old_end = object->address() + old_size; Address new_end = old_end - bytes_to_trim; // Register the array as an object with invalidated old-to-old slots. We // cannot use NotifyObjectLayoutChange as it would mark the array black, // which is not safe for left-trimming because left-trimming re-pushes // only grey arrays onto the marking worklist. if (incremental_marking()->IsCompacting() && MayContainRecordedSlots(object)) { // Ensure that the object survives because the InvalidatedSlotsFilter will // compute its size from its map during pointers updating phase. incremental_marking()->WhiteToGreyAndPush(object); MemoryChunk::FromHeapObject(object)->RegisterObjectWithInvalidatedSlots( object, old_size); } // Technically in new space this write might be omitted (except for // debug mode which iterates through the heap), but to play safer // we still do it. // We do not create a filler for objects in large object space. // TODO(hpayer): We should shrink the large object page if the size // of the object changed significantly. if (!lo_space()->Contains(object)) { HeapObject* filler = CreateFillerObjectAt(new_end, bytes_to_trim, ClearRecordedSlots::kYes); DCHECK_NOT_NULL(filler); // Clear the mark bits of the black area that belongs now to the filler. // This is an optimization. The sweeper will release black fillers anyway. if (incremental_marking()->black_allocation() && incremental_marking()->marking_state()->IsBlackOrGrey(filler)) { Page* page = Page::FromAddress(new_end); incremental_marking()->marking_state()->bitmap(page)->ClearRange( page->AddressToMarkbitIndex(new_end), page->AddressToMarkbitIndex(new_end + bytes_to_trim)); } } // Initialize header of the trimmed array. We are storing the new length // using release store after creating a filler for the left-over space to // avoid races with the sweeper thread. object->synchronized_set_length(object->length() - elements_to_trim); // Notify the heap object allocation tracker of change in object layout. The // array may not be moved during GC, and size has to be adjusted nevertheless. for (auto& tracker : allocation_trackers_) { tracker->UpdateObjectSizeEvent(object->address(), object->Size()); } } void Heap::MakeHeapIterable() { mark_compact_collector()->EnsureSweepingCompleted(); } static double ComputeMutatorUtilization(double mutator_speed, double gc_speed) { const double kMinMutatorUtilization = 0.0; const double kConservativeGcSpeedInBytesPerMillisecond = 200000; if (mutator_speed == 0) return kMinMutatorUtilization; if (gc_speed == 0) gc_speed = kConservativeGcSpeedInBytesPerMillisecond; // Derivation: // mutator_utilization = mutator_time / (mutator_time + gc_time) // mutator_time = 1 / mutator_speed // gc_time = 1 / gc_speed // mutator_utilization = (1 / mutator_speed) / // (1 / mutator_speed + 1 / gc_speed) // mutator_utilization = gc_speed / (mutator_speed + gc_speed) return gc_speed / (mutator_speed + gc_speed); } double Heap::YoungGenerationMutatorUtilization() { double mutator_speed = static_cast( tracer()->NewSpaceAllocationThroughputInBytesPerMillisecond()); double gc_speed = tracer()->ScavengeSpeedInBytesPerMillisecond(kForSurvivedObjects); double result = ComputeMutatorUtilization(mutator_speed, gc_speed); if (FLAG_trace_mutator_utilization) { isolate()->PrintWithTimestamp( "Young generation mutator utilization = %.3f (" "mutator_speed=%.f, gc_speed=%.f)\n", result, mutator_speed, gc_speed); } return result; } double Heap::OldGenerationMutatorUtilization() { double mutator_speed = static_cast( tracer()->OldGenerationAllocationThroughputInBytesPerMillisecond()); double gc_speed = static_cast( tracer()->CombinedMarkCompactSpeedInBytesPerMillisecond()); double result = ComputeMutatorUtilization(mutator_speed, gc_speed); if (FLAG_trace_mutator_utilization) { isolate()->PrintWithTimestamp( "Old generation mutator utilization = %.3f (" "mutator_speed=%.f, gc_speed=%.f)\n", result, mutator_speed, gc_speed); } return result; } bool Heap::HasLowYoungGenerationAllocationRate() { const double high_mutator_utilization = 0.993; return YoungGenerationMutatorUtilization() > high_mutator_utilization; } bool Heap::HasLowOldGenerationAllocationRate() { const double high_mutator_utilization = 0.993; return OldGenerationMutatorUtilization() > high_mutator_utilization; } bool Heap::HasLowAllocationRate() { return HasLowYoungGenerationAllocationRate() && HasLowOldGenerationAllocationRate(); } bool Heap::IsIneffectiveMarkCompact(size_t old_generation_size, double mutator_utilization) { const double kHighHeapPercentage = 0.8; const double kLowMutatorUtilization = 0.4; return old_generation_size >= kHighHeapPercentage * max_old_generation_size_ && mutator_utilization < kLowMutatorUtilization; } void Heap::CheckIneffectiveMarkCompact(size_t old_generation_size, double mutator_utilization) { const int kMaxConsecutiveIneffectiveMarkCompacts = 4; if (!FLAG_detect_ineffective_gcs_near_heap_limit) return; if (!IsIneffectiveMarkCompact(old_generation_size, mutator_utilization)) { consecutive_ineffective_mark_compacts_ = 0; return; } ++consecutive_ineffective_mark_compacts_; if (consecutive_ineffective_mark_compacts_ == kMaxConsecutiveIneffectiveMarkCompacts) { if (InvokeNearHeapLimitCallback()) { // The callback increased the heap limit. consecutive_ineffective_mark_compacts_ = 0; return; } FatalProcessOutOfMemory("Ineffective mark-compacts near heap limit"); } } bool Heap::HasHighFragmentation() { size_t used = OldGenerationSizeOfObjects(); size_t committed = CommittedOldGenerationMemory(); return HasHighFragmentation(used, committed); } bool Heap::HasHighFragmentation(size_t used, size_t committed) { const size_t kSlack = 16 * MB; // Fragmentation is high if committed > 2 * used + kSlack. // Rewrite the exression to avoid overflow. DCHECK_GE(committed, used); return committed - used > used + kSlack; } bool Heap::ShouldOptimizeForMemoryUsage() { const size_t kOldGenerationSlack = max_old_generation_size_ / 8; return FLAG_optimize_for_size || isolate()->IsIsolateInBackground() || isolate()->IsMemorySavingsModeActive() || HighMemoryPressure() || !CanExpandOldGeneration(kOldGenerationSlack); } void Heap::ActivateMemoryReducerIfNeeded() { // Activate memory reducer when switching to background if // - there was no mark compact since the start. // - the committed memory can be potentially reduced. // 2 pages for the old, code, and map space + 1 page for new space. const int kMinCommittedMemory = 7 * Page::kPageSize; if (ms_count_ == 0 && CommittedMemory() > kMinCommittedMemory && isolate()->IsIsolateInBackground()) { MemoryReducer::Event event; event.type = MemoryReducer::kPossibleGarbage; event.time_ms = MonotonicallyIncreasingTimeInMs(); memory_reducer_->NotifyPossibleGarbage(event); } } void Heap::ReduceNewSpaceSize() { // TODO(ulan): Unify this constant with the similar constant in // GCIdleTimeHandler once the change is merged to 4.5. static const size_t kLowAllocationThroughput = 1000; const double allocation_throughput = tracer()->CurrentAllocationThroughputInBytesPerMillisecond(); if (FLAG_predictable) return; if (ShouldReduceMemory() || ((allocation_throughput != 0) && (allocation_throughput < kLowAllocationThroughput))) { new_space_->Shrink(); UncommitFromSpace(); } } void Heap::FinalizeIncrementalMarkingIfComplete( GarbageCollectionReason gc_reason) { if (incremental_marking()->IsMarking() && (incremental_marking()->IsReadyToOverApproximateWeakClosure() || (!incremental_marking()->finalize_marking_completed() && mark_compact_collector()->marking_worklist()->IsEmpty() && local_embedder_heap_tracer()->ShouldFinalizeIncrementalMarking()))) { FinalizeIncrementalMarkingIncrementally(gc_reason); } else if (incremental_marking()->IsComplete() || (mark_compact_collector()->marking_worklist()->IsEmpty() && local_embedder_heap_tracer() ->ShouldFinalizeIncrementalMarking())) { CollectAllGarbage(current_gc_flags_, gc_reason, current_gc_callback_flags_); } } void Heap::FinalizeIncrementalMarkingAtomically( GarbageCollectionReason gc_reason) { DCHECK(!incremental_marking()->IsStopped()); CollectAllGarbage(current_gc_flags_, gc_reason, current_gc_callback_flags_); } void Heap::FinalizeIncrementalMarkingIncrementally( GarbageCollectionReason gc_reason) { if (FLAG_trace_incremental_marking) { isolate()->PrintWithTimestamp( "[IncrementalMarking] (%s).\n", Heap::GarbageCollectionReasonToString(gc_reason)); } HistogramTimerScope incremental_marking_scope( isolate()->counters()->gc_incremental_marking_finalize()); TRACE_EVENT0("v8", "V8.GCIncrementalMarkingFinalize"); TRACE_GC(tracer(), GCTracer::Scope::MC_INCREMENTAL_FINALIZE); { GCCallbacksScope scope(this); if (scope.CheckReenter()) { AllowHeapAllocation allow_allocation; TRACE_GC(tracer(), GCTracer::Scope::MC_INCREMENTAL_EXTERNAL_PROLOGUE); VMState state(isolate_); HandleScope handle_scope(isolate_); CallGCPrologueCallbacks(kGCTypeIncrementalMarking, kNoGCCallbackFlags); } } incremental_marking()->FinalizeIncrementally(); { GCCallbacksScope scope(this); if (scope.CheckReenter()) { AllowHeapAllocation allow_allocation; TRACE_GC(tracer(), GCTracer::Scope::MC_INCREMENTAL_EXTERNAL_EPILOGUE); VMState state(isolate_); HandleScope handle_scope(isolate_); CallGCEpilogueCallbacks(kGCTypeIncrementalMarking, kNoGCCallbackFlags); } } } void Heap::RegisterDeserializedObjectsForBlackAllocation( Reservation* reservations, const std::vector& large_objects, const std::vector
& maps) { // TODO(ulan): pause black allocation during deserialization to avoid // iterating all these objects in one go. if (!incremental_marking()->black_allocation()) return; // Iterate black objects in old space, code space, map space, and large // object space for side effects. IncrementalMarking::MarkingState* marking_state = incremental_marking()->marking_state(); for (int i = OLD_SPACE; i < Serializer<>::kNumberOfSpaces; i++) { const Heap::Reservation& res = reservations[i]; for (auto& chunk : res) { Address addr = chunk.start; while (addr < chunk.end) { HeapObject* obj = HeapObject::FromAddress(addr); // Objects can have any color because incremental marking can // start in the middle of Heap::ReserveSpace(). if (marking_state->IsBlack(obj)) { incremental_marking()->ProcessBlackAllocatedObject(obj); } addr += obj->Size(); } } } // We potentially deserialized wrappers which require registering with the // embedder as the marker will not find them. local_embedder_heap_tracer()->RegisterWrappersWithRemoteTracer(); // Large object space doesn't use reservations, so it needs custom handling. for (HeapObject* object : large_objects) { incremental_marking()->ProcessBlackAllocatedObject(object); } // Map space doesn't use reservations, so it needs custom handling. for (Address addr : maps) { incremental_marking()->ProcessBlackAllocatedObject( HeapObject::FromAddress(addr)); } } void Heap::NotifyObjectLayoutChange(HeapObject* object, int size, const DisallowHeapAllocation&) { if (incremental_marking()->IsMarking()) { incremental_marking()->MarkBlackAndPush(object); if (incremental_marking()->IsCompacting() && MayContainRecordedSlots(object)) { MemoryChunk::FromHeapObject(object)->RegisterObjectWithInvalidatedSlots( object, size); } } #ifdef VERIFY_HEAP if (FLAG_verify_heap) { DCHECK_NULL(pending_layout_change_object_); pending_layout_change_object_ = object; } #endif } #ifdef VERIFY_HEAP // Helper class for collecting slot addresses. class SlotCollectingVisitor final : public ObjectVisitor { public: void VisitPointers(HeapObject* host, Object** start, Object** end) override { VisitPointers(host, reinterpret_cast(start), reinterpret_cast(end)); } void VisitPointers(HeapObject* host, MaybeObject** start, MaybeObject** end) final { for (MaybeObject** p = start; p < end; p++) { slots_.push_back(p); } } int number_of_slots() { return static_cast(slots_.size()); } MaybeObject** slot(int i) { return slots_[i]; } private: std::vector slots_; }; void Heap::VerifyObjectLayoutChange(HeapObject* object, Map* new_map) { if (!FLAG_verify_heap) return; // Check that Heap::NotifyObjectLayout was called for object transitions // that are not safe for concurrent marking. // If you see this check triggering for a freshly allocated object, // use object->set_map_after_allocation() to initialize its map. if (pending_layout_change_object_ == nullptr) { if (object->IsJSObject()) { DCHECK(!object->map()->TransitionRequiresSynchronizationWithGC(new_map)); } else { // Check that the set of slots before and after the transition match. SlotCollectingVisitor old_visitor; object->IterateFast(&old_visitor); MapWord old_map_word = object->map_word(); // Temporarily set the new map to iterate new slots. object->set_map_word(MapWord::FromMap(new_map)); SlotCollectingVisitor new_visitor; object->IterateFast(&new_visitor); // Restore the old map. object->set_map_word(old_map_word); DCHECK_EQ(new_visitor.number_of_slots(), old_visitor.number_of_slots()); for (int i = 0; i < new_visitor.number_of_slots(); i++) { DCHECK_EQ(new_visitor.slot(i), old_visitor.slot(i)); } } } else { DCHECK_EQ(pending_layout_change_object_, object); pending_layout_change_object_ = nullptr; } } #endif GCIdleTimeHeapState Heap::ComputeHeapState() { GCIdleTimeHeapState heap_state; heap_state.contexts_disposed = contexts_disposed_; heap_state.contexts_disposal_rate = tracer()->ContextDisposalRateInMilliseconds(); heap_state.size_of_objects = static_cast(SizeOfObjects()); heap_state.incremental_marking_stopped = incremental_marking()->IsStopped(); return heap_state; } bool Heap::PerformIdleTimeAction(GCIdleTimeAction action, GCIdleTimeHeapState heap_state, double deadline_in_ms) { bool result = false; switch (action.type) { case DONE: result = true; break; case DO_INCREMENTAL_STEP: { const double remaining_idle_time_in_ms = incremental_marking()->AdvanceIncrementalMarking( deadline_in_ms, IncrementalMarking::NO_GC_VIA_STACK_GUARD, StepOrigin::kTask); if (remaining_idle_time_in_ms > 0.0) { FinalizeIncrementalMarkingIfComplete( GarbageCollectionReason::kFinalizeMarkingViaTask); } result = incremental_marking()->IsStopped(); break; } case DO_FULL_GC: { DCHECK_LT(0, contexts_disposed_); HistogramTimerScope scope(isolate_->counters()->gc_context()); TRACE_EVENT0("v8", "V8.GCContext"); CollectAllGarbage(kNoGCFlags, GarbageCollectionReason::kContextDisposal); break; } case DO_NOTHING: break; } return result; } void Heap::IdleNotificationEpilogue(GCIdleTimeAction action, GCIdleTimeHeapState heap_state, double start_ms, double deadline_in_ms) { double idle_time_in_ms = deadline_in_ms - start_ms; double current_time = MonotonicallyIncreasingTimeInMs(); last_idle_notification_time_ = current_time; double deadline_difference = deadline_in_ms - current_time; contexts_disposed_ = 0; if ((FLAG_trace_idle_notification && action.type > DO_NOTHING) || FLAG_trace_idle_notification_verbose) { isolate_->PrintWithTimestamp( "Idle notification: requested idle time %.2f ms, used idle time %.2f " "ms, deadline usage %.2f ms [", idle_time_in_ms, idle_time_in_ms - deadline_difference, deadline_difference); action.Print(); PrintF("]"); if (FLAG_trace_idle_notification_verbose) { PrintF("["); heap_state.Print(); PrintF("]"); } PrintF("\n"); } } double Heap::MonotonicallyIncreasingTimeInMs() { return V8::GetCurrentPlatform()->MonotonicallyIncreasingTime() * static_cast(base::Time::kMillisecondsPerSecond); } bool Heap::IdleNotification(int idle_time_in_ms) { return IdleNotification( V8::GetCurrentPlatform()->MonotonicallyIncreasingTime() + (static_cast(idle_time_in_ms) / static_cast(base::Time::kMillisecondsPerSecond))); } bool Heap::IdleNotification(double deadline_in_seconds) { CHECK(HasBeenSetUp()); double deadline_in_ms = deadline_in_seconds * static_cast(base::Time::kMillisecondsPerSecond); HistogramTimerScope idle_notification_scope( isolate_->counters()->gc_idle_notification()); TRACE_EVENT0("v8", "V8.GCIdleNotification"); double start_ms = MonotonicallyIncreasingTimeInMs(); double idle_time_in_ms = deadline_in_ms - start_ms; tracer()->SampleAllocation(start_ms, NewSpaceAllocationCounter(), OldGenerationAllocationCounter()); GCIdleTimeHeapState heap_state = ComputeHeapState(); GCIdleTimeAction action = gc_idle_time_handler_->Compute(idle_time_in_ms, heap_state); bool result = PerformIdleTimeAction(action, heap_state, deadline_in_ms); IdleNotificationEpilogue(action, heap_state, start_ms, deadline_in_ms); return result; } bool Heap::RecentIdleNotificationHappened() { return (last_idle_notification_time_ + GCIdleTimeHandler::kMaxScheduledIdleTime) > MonotonicallyIncreasingTimeInMs(); } class MemoryPressureInterruptTask : public CancelableTask { public: explicit MemoryPressureInterruptTask(Heap* heap) : CancelableTask(heap->isolate()), heap_(heap) {} ~MemoryPressureInterruptTask() override = default; private: // v8::internal::CancelableTask overrides. void RunInternal() override { heap_->CheckMemoryPressure(); } Heap* heap_; DISALLOW_COPY_AND_ASSIGN(MemoryPressureInterruptTask); }; void Heap::CheckMemoryPressure() { if (HighMemoryPressure()) { // The optimizing compiler may be unnecessarily holding on to memory. isolate()->AbortConcurrentOptimization(BlockingBehavior::kDontBlock); } MemoryPressureLevel memory_pressure_level = memory_pressure_level_; // Reset the memory pressure level to avoid recursive GCs triggered by // CheckMemoryPressure from AdjustAmountOfExternalMemory called by // the finalizers. memory_pressure_level_ = MemoryPressureLevel::kNone; if (memory_pressure_level == MemoryPressureLevel::kCritical) { CollectGarbageOnMemoryPressure(); } else if (memory_pressure_level == MemoryPressureLevel::kModerate) { if (FLAG_incremental_marking && incremental_marking()->IsStopped()) { StartIncrementalMarking(kReduceMemoryFootprintMask, GarbageCollectionReason::kMemoryPressure); } } if (memory_reducer_) { MemoryReducer::Event event; event.type = MemoryReducer::kPossibleGarbage; event.time_ms = MonotonicallyIncreasingTimeInMs(); memory_reducer_->NotifyPossibleGarbage(event); } } void Heap::CollectGarbageOnMemoryPressure() { const int kGarbageThresholdInBytes = 8 * MB; const double kGarbageThresholdAsFractionOfTotalMemory = 0.1; // This constant is the maximum response time in RAIL performance model. const double kMaxMemoryPressurePauseMs = 100; double start = MonotonicallyIncreasingTimeInMs(); CollectAllGarbage(kReduceMemoryFootprintMask, GarbageCollectionReason::kMemoryPressure, kGCCallbackFlagCollectAllAvailableGarbage); EagerlyFreeExternalMemory(); double end = MonotonicallyIncreasingTimeInMs(); // Estimate how much memory we can free. int64_t potential_garbage = (CommittedMemory() - SizeOfObjects()) + external_memory_; // If we can potentially free large amount of memory, then start GC right // away instead of waiting for memory reducer. if (potential_garbage >= kGarbageThresholdInBytes && potential_garbage >= CommittedMemory() * kGarbageThresholdAsFractionOfTotalMemory) { // If we spent less than half of the time budget, then perform full GC // Otherwise, start incremental marking. if (end - start < kMaxMemoryPressurePauseMs / 2) { CollectAllGarbage(kReduceMemoryFootprintMask, GarbageCollectionReason::kMemoryPressure, kGCCallbackFlagCollectAllAvailableGarbage); } else { if (FLAG_incremental_marking && incremental_marking()->IsStopped()) { StartIncrementalMarking(kReduceMemoryFootprintMask, GarbageCollectionReason::kMemoryPressure); } } } } void Heap::MemoryPressureNotification(MemoryPressureLevel level, bool is_isolate_locked) { MemoryPressureLevel previous = memory_pressure_level_; memory_pressure_level_ = level; if ((previous != MemoryPressureLevel::kCritical && level == MemoryPressureLevel::kCritical) || (previous == MemoryPressureLevel::kNone && level == MemoryPressureLevel::kModerate)) { if (is_isolate_locked) { CheckMemoryPressure(); } else { ExecutionAccess access(isolate()); isolate()->stack_guard()->RequestGC(); auto taskrunner = V8::GetCurrentPlatform()->GetForegroundTaskRunner( reinterpret_cast(isolate())); taskrunner->PostTask( base::make_unique(this)); } } } void Heap::EagerlyFreeExternalMemory() { for (Page* page : *old_space()) { if (!page->SweepingDone()) { base::LockGuard guard(page->mutex()); if (!page->SweepingDone()) { ArrayBufferTracker::FreeDead( page, mark_compact_collector()->non_atomic_marking_state()); } } } memory_allocator()->unmapper()->EnsureUnmappingCompleted(); } void Heap::AddNearHeapLimitCallback(v8::NearHeapLimitCallback callback, void* data) { const size_t kMaxCallbacks = 100; CHECK_LT(near_heap_limit_callbacks_.size(), kMaxCallbacks); for (auto callback_data : near_heap_limit_callbacks_) { CHECK_NE(callback_data.first, callback); } near_heap_limit_callbacks_.push_back(std::make_pair(callback, data)); } void Heap::RemoveNearHeapLimitCallback(v8::NearHeapLimitCallback callback, size_t heap_limit) { for (size_t i = 0; i < near_heap_limit_callbacks_.size(); i++) { if (near_heap_limit_callbacks_[i].first == callback) { near_heap_limit_callbacks_.erase(near_heap_limit_callbacks_.begin() + i); if (heap_limit) { RestoreHeapLimit(heap_limit); } return; } } UNREACHABLE(); } bool Heap::InvokeNearHeapLimitCallback() { if (near_heap_limit_callbacks_.size() > 0) { HandleScope scope(isolate()); v8::NearHeapLimitCallback callback = near_heap_limit_callbacks_.back().first; void* data = near_heap_limit_callbacks_.back().second; size_t heap_limit = callback(data, max_old_generation_size_, initial_max_old_generation_size_); if (heap_limit > max_old_generation_size_) { max_old_generation_size_ = heap_limit; return true; } } return false; } void Heap::CollectCodeStatistics() { TRACE_EVENT0("v8", "Heap::CollectCodeStatistics"); CodeStatistics::ResetCodeAndMetadataStatistics(isolate()); // We do not look for code in new space, or map space. If code // somehow ends up in those spaces, we would miss it here. CodeStatistics::CollectCodeStatistics(code_space_, isolate()); CodeStatistics::CollectCodeStatistics(old_space_, isolate()); CodeStatistics::CollectCodeStatistics(lo_space_, isolate()); } #ifdef DEBUG void Heap::Print() { if (!HasBeenSetUp()) return; isolate()->PrintStack(stdout); for (SpaceIterator it(this); it.has_next();) { it.next()->Print(); } } void Heap::ReportCodeStatistics(const char* title) { PrintF(">>>>>> Code Stats (%s) >>>>>>\n", title); CollectCodeStatistics(); CodeStatistics::ReportCodeStatistics(isolate()); } #endif // DEBUG const char* Heap::GarbageCollectionReasonToString( GarbageCollectionReason gc_reason) { switch (gc_reason) { case GarbageCollectionReason::kAllocationFailure: return "allocation failure"; case GarbageCollectionReason::kAllocationLimit: return "allocation limit"; case GarbageCollectionReason::kContextDisposal: return "context disposal"; case GarbageCollectionReason::kCountersExtension: return "counters extension"; case GarbageCollectionReason::kDebugger: return "debugger"; case GarbageCollectionReason::kDeserializer: return "deserialize"; case GarbageCollectionReason::kExternalMemoryPressure: return "external memory pressure"; case GarbageCollectionReason::kFinalizeMarkingViaStackGuard: return "finalize incremental marking via stack guard"; case GarbageCollectionReason::kFinalizeMarkingViaTask: return "finalize incremental marking via task"; case GarbageCollectionReason::kFullHashtable: return "full hash-table"; case GarbageCollectionReason::kHeapProfiler: return "heap profiler"; case GarbageCollectionReason::kIdleTask: return "idle task"; case GarbageCollectionReason::kLastResort: return "last resort"; case GarbageCollectionReason::kLowMemoryNotification: return "low memory notification"; case GarbageCollectionReason::kMakeHeapIterable: return "make heap iterable"; case GarbageCollectionReason::kMemoryPressure: return "memory pressure"; case GarbageCollectionReason::kMemoryReducer: return "memory reducer"; case GarbageCollectionReason::kRuntime: return "runtime"; case GarbageCollectionReason::kSamplingProfiler: return "sampling profiler"; case GarbageCollectionReason::kSnapshotCreator: return "snapshot creator"; case GarbageCollectionReason::kTesting: return "testing"; case GarbageCollectionReason::kExternalFinalize: return "external finalize"; case GarbageCollectionReason::kUnknown: return "unknown"; } UNREACHABLE(); } bool Heap::Contains(HeapObject* value) { if (memory_allocator()->IsOutsideAllocatedSpace(value->address())) { return false; } return HasBeenSetUp() && (new_space_->ToSpaceContains(value) || old_space_->Contains(value) || code_space_->Contains(value) || map_space_->Contains(value) || lo_space_->Contains(value) || read_only_space_->Contains(value)); } bool Heap::ContainsSlow(Address addr) { if (memory_allocator()->IsOutsideAllocatedSpace(addr)) { return false; } return HasBeenSetUp() && (new_space_->ToSpaceContainsSlow(addr) || old_space_->ContainsSlow(addr) || code_space_->ContainsSlow(addr) || map_space_->ContainsSlow(addr) || lo_space_->ContainsSlow(addr) || read_only_space_->Contains(addr)); } bool Heap::InSpace(HeapObject* value, AllocationSpace space) { if (memory_allocator()->IsOutsideAllocatedSpace(value->address())) { return false; } if (!HasBeenSetUp()) return false; switch (space) { case NEW_SPACE: return new_space_->ToSpaceContains(value); case OLD_SPACE: return old_space_->Contains(value); case CODE_SPACE: return code_space_->Contains(value); case MAP_SPACE: return map_space_->Contains(value); case LO_SPACE: return lo_space_->Contains(value); case NEW_LO_SPACE: return new_lo_space_->Contains(value); case RO_SPACE: return read_only_space_->Contains(value); } UNREACHABLE(); } bool Heap::InSpaceSlow(Address addr, AllocationSpace space) { if (memory_allocator()->IsOutsideAllocatedSpace(addr)) { return false; } if (!HasBeenSetUp()) return false; switch (space) { case NEW_SPACE: return new_space_->ToSpaceContainsSlow(addr); case OLD_SPACE: return old_space_->ContainsSlow(addr); case CODE_SPACE: return code_space_->ContainsSlow(addr); case MAP_SPACE: return map_space_->ContainsSlow(addr); case LO_SPACE: return lo_space_->ContainsSlow(addr); case NEW_LO_SPACE: return new_lo_space_->ContainsSlow(addr); case RO_SPACE: return read_only_space_->ContainsSlow(addr); } UNREACHABLE(); } bool Heap::IsValidAllocationSpace(AllocationSpace space) { switch (space) { case NEW_SPACE: case OLD_SPACE: case CODE_SPACE: case MAP_SPACE: case LO_SPACE: case NEW_LO_SPACE: case RO_SPACE: return true; default: return false; } } bool Heap::RootIsImmortalImmovable(RootIndex root_index) { switch (root_index) { #define IMMORTAL_IMMOVABLE_ROOT(name) case RootIndex::k##name: IMMORTAL_IMMOVABLE_ROOT_LIST(IMMORTAL_IMMOVABLE_ROOT) #undef IMMORTAL_IMMOVABLE_ROOT #define INTERNALIZED_STRING(_, name, value) case RootIndex::k##name: INTERNALIZED_STRING_LIST_GENERATOR(INTERNALIZED_STRING, /* not used */) #undef INTERNALIZED_STRING #define STRING_TYPE(NAME, size, name, Name) case RootIndex::k##Name##Map: STRING_TYPE_LIST(STRING_TYPE) #undef STRING_TYPE return true; default: return false; } } #ifdef VERIFY_HEAP class VerifyReadOnlyPointersVisitor : public VerifyPointersVisitor { public: explicit VerifyReadOnlyPointersVisitor(Heap* heap) : VerifyPointersVisitor(heap) {} protected: void VerifyPointers(HeapObject* host, MaybeObject** start, MaybeObject** end) override { if (host != nullptr) { CHECK(heap_->InReadOnlySpace(host->map())); } VerifyPointersVisitor::VerifyPointers(host, start, end); for (MaybeObject** current = start; current < end; current++) { HeapObject* object; if ((*current)->GetHeapObject(&object)) { CHECK(heap_->InReadOnlySpace(object)); } } } }; void Heap::Verify() { CHECK(HasBeenSetUp()); HandleScope scope(isolate()); // We have to wait here for the sweeper threads to have an iterable heap. mark_compact_collector()->EnsureSweepingCompleted(); VerifyPointersVisitor visitor(this); IterateRoots(&visitor, VISIT_ONLY_STRONG); VerifySmisVisitor smis_visitor; IterateSmiRoots(&smis_visitor); new_space_->Verify(isolate()); old_space_->Verify(isolate(), &visitor); map_space_->Verify(isolate(), &visitor); VerifyPointersVisitor no_dirty_regions_visitor(this); code_space_->Verify(isolate(), &no_dirty_regions_visitor); lo_space_->Verify(isolate()); VerifyReadOnlyPointersVisitor read_only_visitor(this); read_only_space_->Verify(isolate(), &read_only_visitor); } class SlotVerifyingVisitor : public ObjectVisitor { public: SlotVerifyingVisitor(std::set
* untyped, std::set >* typed) : untyped_(untyped), typed_(typed) {} virtual bool ShouldHaveBeenRecorded(HeapObject* host, MaybeObject* target) = 0; void VisitPointers(HeapObject* host, Object** start, Object** end) override { #ifdef DEBUG for (Object** slot = start; slot < end; slot++) { DCHECK(!HasWeakHeapObjectTag(*slot)); } #endif // DEBUG VisitPointers(host, reinterpret_cast(start), reinterpret_cast(end)); } void VisitPointers(HeapObject* host, MaybeObject** start, MaybeObject** end) final { for (MaybeObject** slot = start; slot < end; slot++) { if (ShouldHaveBeenRecorded(host, *slot)) { CHECK_GT(untyped_->count(reinterpret_cast
(slot)), 0); } } } void VisitCodeTarget(Code* host, RelocInfo* rinfo) override { Object* target = Code::GetCodeFromTargetAddress(rinfo->target_address()); if (ShouldHaveBeenRecorded(host, MaybeObject::FromObject(target))) { CHECK( InTypedSet(CODE_TARGET_SLOT, rinfo->pc()) || (rinfo->IsInConstantPool() && InTypedSet(CODE_ENTRY_SLOT, rinfo->constant_pool_entry_address()))); } } void VisitEmbeddedPointer(Code* host, RelocInfo* rinfo) override { Object* target = rinfo->target_object(); if (ShouldHaveBeenRecorded(host, MaybeObject::FromObject(target))) { CHECK(InTypedSet(EMBEDDED_OBJECT_SLOT, rinfo->pc()) || (rinfo->IsInConstantPool() && InTypedSet(OBJECT_SLOT, rinfo->constant_pool_entry_address()))); } } private: bool InTypedSet(SlotType type, Address slot) { return typed_->count(std::make_pair(type, slot)) > 0; } std::set
* untyped_; std::set >* typed_; }; class OldToNewSlotVerifyingVisitor : public SlotVerifyingVisitor { public: OldToNewSlotVerifyingVisitor(std::set
* untyped, std::set>* typed) : SlotVerifyingVisitor(untyped, typed) {} bool ShouldHaveBeenRecorded(HeapObject* host, MaybeObject* target) override { DCHECK_IMPLIES(target->IsStrongOrWeak() && Heap::InNewSpace(target), Heap::InToSpace(target)); return target->IsStrongOrWeak() && Heap::InNewSpace(target) && !Heap::InNewSpace(host); } }; template void CollectSlots(MemoryChunk* chunk, Address start, Address end, std::set
* untyped, std::set >* typed) { RememberedSet::Iterate(chunk, [start, end, untyped](Address slot) { if (start <= slot && slot < end) { untyped->insert(slot); } return KEEP_SLOT; }, SlotSet::PREFREE_EMPTY_BUCKETS); RememberedSet::IterateTyped( chunk, [start, end, typed](SlotType type, Address host, Address slot) { if (start <= slot && slot < end) { typed->insert(std::make_pair(type, slot)); } return KEEP_SLOT; }); } void Heap::VerifyRememberedSetFor(HeapObject* object) { MemoryChunk* chunk = MemoryChunk::FromAddress(object->address()); DCHECK_IMPLIES(chunk->mutex() == nullptr, InReadOnlySpace(object)); // In RO_SPACE chunk->mutex() may be nullptr, so just ignore it. base::LockGuard lock_guard( chunk->mutex()); Address start = object->address(); Address end = start + object->Size(); std::set
old_to_new; std::set > typed_old_to_new; if (!InNewSpace(object)) { store_buffer()->MoveAllEntriesToRememberedSet(); CollectSlots(chunk, start, end, &old_to_new, &typed_old_to_new); OldToNewSlotVerifyingVisitor visitor(&old_to_new, &typed_old_to_new); object->IterateBody(&visitor); } // TODO(ulan): Add old to old slot set verification once all weak objects // have their own instance types and slots are recorded for all weal fields. } #endif #ifdef DEBUG void Heap::VerifyCountersAfterSweeping() { PagedSpaces spaces(this); for (PagedSpace* space = spaces.next(); space != nullptr; space = spaces.next()) { space->VerifyCountersAfterSweeping(); } } void Heap::VerifyCountersBeforeConcurrentSweeping() { PagedSpaces spaces(this); for (PagedSpace* space = spaces.next(); space != nullptr; space = spaces.next()) { space->VerifyCountersBeforeConcurrentSweeping(); } } #endif void Heap::ZapFromSpace() { if (!new_space_->IsFromSpaceCommitted()) return; for (Page* page : PageRange(new_space_->from_space().first_page(), nullptr)) { memory_allocator()->ZapBlock(page->area_start(), page->HighWaterMark() - page->area_start(), ZapValue()); } } void Heap::ZapCodeObject(Address start_address, int size_in_bytes) { #ifdef DEBUG for (int i = 0; i < size_in_bytes / kPointerSize; i++) { reinterpret_cast(start_address)[i] = Smi::FromInt(kCodeZapValue); } #endif } Code* Heap::builtin(int index) { DCHECK(Builtins::IsBuiltinId(index)); // Code::cast cannot be used here since we access builtins // during the marking phase of mark sweep. See IC::Clear. return reinterpret_cast(builtins_[index]); } Address Heap::builtin_address(int index) { DCHECK(Builtins::IsBuiltinId(index) || index == Builtins::builtin_count); return reinterpret_cast
(&builtins_[index]); } void Heap::set_builtin(int index, HeapObject* builtin) { DCHECK(Builtins::IsBuiltinId(index)); DCHECK(Internals::HasHeapObjectTag(builtin)); // The given builtin may be completely uninitialized thus we cannot check its // type here. builtins_[index] = builtin; } void Heap::IterateRoots(RootVisitor* v, VisitMode mode) { IterateStrongRoots(v, mode); IterateWeakRoots(v, mode); } void Heap::IterateWeakRoots(RootVisitor* v, VisitMode mode) { const bool isMinorGC = mode == VISIT_ALL_IN_SCAVENGE || mode == VISIT_ALL_IN_MINOR_MC_MARK || mode == VISIT_ALL_IN_MINOR_MC_UPDATE; v->VisitRootPointer(Root::kStringTable, nullptr, &roots_[RootIndex::kStringTable]); v->Synchronize(VisitorSynchronization::kStringTable); if (!isMinorGC && mode != VISIT_ALL_IN_SWEEP_NEWSPACE && mode != VISIT_FOR_SERIALIZATION) { // Scavenge collections have special processing for this. // Do not visit for serialization, since the external string table will // be populated from scratch upon deserialization. external_string_table_.IterateAll(v); } v->Synchronize(VisitorSynchronization::kExternalStringsTable); } void Heap::IterateSmiRoots(RootVisitor* v) { // Acquire execution access since we are going to read stack limit values. ExecutionAccess access(isolate()); v->VisitRootPointers(Root::kSmiRootList, nullptr, roots_.smi_roots_begin(), roots_.smi_roots_end()); v->Synchronize(VisitorSynchronization::kSmiRootList); } // We cannot avoid stale handles to left-trimmed objects, but can only make // sure all handles still needed are updated. Filter out a stale pointer // and clear the slot to allow post processing of handles (needed because // the sweeper might actually free the underlying page). class FixStaleLeftTrimmedHandlesVisitor : public RootVisitor { public: explicit FixStaleLeftTrimmedHandlesVisitor(Heap* heap) : heap_(heap) { USE(heap_); } void VisitRootPointer(Root root, const char* description, Object** p) override { FixHandle(p); } void VisitRootPointers(Root root, const char* description, Object** start, Object** end) override { for (Object** p = start; p < end; p++) FixHandle(p); } private: inline void FixHandle(Object** p) { if (!(*p)->IsHeapObject()) return; HeapObject* current = reinterpret_cast(*p); const MapWord map_word = current->map_word(); if (!map_word.IsForwardingAddress() && current->IsFiller()) { #ifdef DEBUG // We need to find a FixedArrayBase map after walking the fillers. while (current->IsFiller()) { Address next = reinterpret_cast
(current); if (current->map() == ReadOnlyRoots(heap_).one_pointer_filler_map()) { next += kPointerSize; } else if (current->map() == ReadOnlyRoots(heap_).two_pointer_filler_map()) { next += 2 * kPointerSize; } else { next += current->Size(); } current = reinterpret_cast(next); } DCHECK(current->IsFixedArrayBase()); #endif // DEBUG *p = nullptr; } } Heap* heap_; }; void Heap::IterateStrongRoots(RootVisitor* v, VisitMode mode) { const bool isMinorGC = mode == VISIT_ALL_IN_SCAVENGE || mode == VISIT_ALL_IN_MINOR_MC_MARK || mode == VISIT_ALL_IN_MINOR_MC_UPDATE; // Garbage collection can skip over the read-only roots. const bool isGC = mode != VISIT_ALL && mode != VISIT_FOR_SERIALIZATION && mode != VISIT_ONLY_STRONG_FOR_SERIALIZATION; Object** start = isGC ? roots_.read_only_roots_end() : roots_.strong_roots_begin(); v->VisitRootPointers(Root::kStrongRootList, nullptr, start, roots_.strong_roots_end()); v->Synchronize(VisitorSynchronization::kStrongRootList); isolate_->bootstrapper()->Iterate(v); v->Synchronize(VisitorSynchronization::kBootstrapper); isolate_->Iterate(v); v->Synchronize(VisitorSynchronization::kTop); Relocatable::Iterate(isolate_, v); v->Synchronize(VisitorSynchronization::kRelocatable); isolate_->debug()->Iterate(v); v->Synchronize(VisitorSynchronization::kDebug); isolate_->compilation_cache()->Iterate(v); v->Synchronize(VisitorSynchronization::kCompilationCache); // Iterate over local handles in handle scopes. FixStaleLeftTrimmedHandlesVisitor left_trim_visitor(this); isolate_->handle_scope_implementer()->Iterate(&left_trim_visitor); isolate_->handle_scope_implementer()->Iterate(v); isolate_->IterateDeferredHandles(v); v->Synchronize(VisitorSynchronization::kHandleScope); // Iterate over the builtin code objects and code stubs in the // heap. Note that it is not necessary to iterate over code objects // on scavenge collections. if (!isMinorGC) { IterateBuiltins(v); v->Synchronize(VisitorSynchronization::kBuiltins); isolate_->interpreter()->IterateDispatchTable(v); v->Synchronize(VisitorSynchronization::kDispatchTable); } // Iterate over global handles. switch (mode) { case VISIT_FOR_SERIALIZATION: // Global handles are not iterated by the serializer. Values referenced by // global handles need to be added manually. break; case VISIT_ONLY_STRONG: case VISIT_ONLY_STRONG_FOR_SERIALIZATION: isolate_->global_handles()->IterateStrongRoots(v); break; case VISIT_ALL_IN_SCAVENGE: isolate_->global_handles()->IterateNewSpaceStrongAndDependentRoots(v); break; case VISIT_ALL_IN_MINOR_MC_MARK: // Global handles are processed manually by the minor MC. break; case VISIT_ALL_IN_MINOR_MC_UPDATE: // Global handles are processed manually by the minor MC. break; case VISIT_ALL_BUT_READ_ONLY: case VISIT_ALL_IN_SWEEP_NEWSPACE: case VISIT_ALL: isolate_->global_handles()->IterateAllRoots(v); break; } v->Synchronize(VisitorSynchronization::kGlobalHandles); // Iterate over eternal handles. Eternal handles are not iterated by the // serializer. Values referenced by eternal handles need to be added manually. if (mode != VISIT_FOR_SERIALIZATION) { if (isMinorGC) { isolate_->eternal_handles()->IterateNewSpaceRoots(v); } else { isolate_->eternal_handles()->IterateAllRoots(v); } } v->Synchronize(VisitorSynchronization::kEternalHandles); // Iterate over pointers being held by inactive threads. isolate_->thread_manager()->Iterate(v); v->Synchronize(VisitorSynchronization::kThreadManager); // Iterate over other strong roots (currently only identity maps). for (StrongRootsList* list = strong_roots_list_; list; list = list->next) { v->VisitRootPointers(Root::kStrongRoots, nullptr, list->start, list->end); } v->Synchronize(VisitorSynchronization::kStrongRoots); // Iterate over the partial snapshot cache unless serializing. if (mode != VISIT_FOR_SERIALIZATION) { SerializerDeserializer::Iterate(isolate_, v); // We don't do a v->Synchronize call here because the serializer and the // deserializer are deliberately out of sync here. } } void Heap::IterateWeakGlobalHandles(RootVisitor* v) { isolate_->global_handles()->IterateWeakRoots(v); } void Heap::IterateBuiltins(RootVisitor* v) { for (int i = 0; i < Builtins::builtin_count; i++) { v->VisitRootPointer(Root::kBuiltins, Builtins::name(i), &builtins_[i]); } } // TODO(1236194): Since the heap size is configurable on the command line // and through the API, we should gracefully handle the case that the heap // size is not big enough to fit all the initial objects. void Heap::ConfigureHeap(size_t max_semi_space_size_in_kb, size_t max_old_generation_size_in_mb, size_t code_range_size_in_mb) { // Overwrite default configuration. if (max_semi_space_size_in_kb != 0) { max_semi_space_size_ = RoundUp(max_semi_space_size_in_kb * KB); } if (max_old_generation_size_in_mb != 0) { max_old_generation_size_ = max_old_generation_size_in_mb * MB; } // If max space size flags are specified overwrite the configuration. if (FLAG_max_semi_space_size > 0) { max_semi_space_size_ = static_cast(FLAG_max_semi_space_size) * MB; } if (FLAG_max_old_space_size > 0) { max_old_generation_size_ = static_cast(FLAG_max_old_space_size) * MB; } if (Page::kPageSize > MB) { max_semi_space_size_ = RoundUp(max_semi_space_size_); max_old_generation_size_ = RoundUp(max_old_generation_size_); } if (FLAG_stress_compaction) { // This will cause more frequent GCs when stressing. max_semi_space_size_ = MB; } // The new space size must be a power of two to support single-bit testing // for containment. max_semi_space_size_ = static_cast(base::bits::RoundUpToPowerOfTwo64( static_cast(max_semi_space_size_))); if (max_semi_space_size_ == kMaxSemiSpaceSizeInKB * KB) { // Start with at least 1*MB semi-space on machines with a lot of memory. initial_semispace_size_ = Max(initial_semispace_size_, static_cast(1 * MB)); } if (FLAG_min_semi_space_size > 0) { size_t initial_semispace_size = static_cast(FLAG_min_semi_space_size) * MB; if (initial_semispace_size > max_semi_space_size_) { initial_semispace_size_ = max_semi_space_size_; if (FLAG_trace_gc) { PrintIsolate(isolate_, "Min semi-space size cannot be more than the maximum " "semi-space size of %" PRIuS " MB\n", max_semi_space_size_ / MB); } } else { initial_semispace_size_ = RoundUp(initial_semispace_size); } } initial_semispace_size_ = Min(initial_semispace_size_, max_semi_space_size_); if (FLAG_semi_space_growth_factor < 2) { FLAG_semi_space_growth_factor = 2; } // The old generation is paged and needs at least one page for each space. int paged_space_count = LAST_GROWABLE_PAGED_SPACE - FIRST_GROWABLE_PAGED_SPACE + 1; initial_max_old_generation_size_ = max_old_generation_size_ = Max(static_cast(paged_space_count * Page::kPageSize), max_old_generation_size_); if (FLAG_initial_old_space_size > 0) { initial_old_generation_size_ = FLAG_initial_old_space_size * MB; } else { initial_old_generation_size_ = max_old_generation_size_ / kInitalOldGenerationLimitFactor; } old_generation_allocation_limit_ = initial_old_generation_size_; // We rely on being able to allocate new arrays in paged spaces. DCHECK(kMaxRegularHeapObjectSize >= (JSArray::kSize + FixedArray::SizeFor(JSArray::kInitialMaxFastElementArray) + AllocationMemento::kSize)); code_range_size_ = code_range_size_in_mb * MB; configured_ = true; } void Heap::AddToRingBuffer(const char* string) { size_t first_part = Min(strlen(string), kTraceRingBufferSize - ring_buffer_end_); memcpy(trace_ring_buffer_ + ring_buffer_end_, string, first_part); ring_buffer_end_ += first_part; if (first_part < strlen(string)) { ring_buffer_full_ = true; size_t second_part = strlen(string) - first_part; memcpy(trace_ring_buffer_, string + first_part, second_part); ring_buffer_end_ = second_part; } } void Heap::GetFromRingBuffer(char* buffer) { size_t copied = 0; if (ring_buffer_full_) { copied = kTraceRingBufferSize - ring_buffer_end_; memcpy(buffer, trace_ring_buffer_ + ring_buffer_end_, copied); } memcpy(buffer + copied, trace_ring_buffer_, ring_buffer_end_); } void Heap::ConfigureHeapDefault() { ConfigureHeap(0, 0, 0); } void Heap::RecordStats(HeapStats* stats, bool take_snapshot) { *stats->start_marker = HeapStats::kStartMarker; *stats->end_marker = HeapStats::kEndMarker; *stats->ro_space_size = read_only_space_->Size(); *stats->ro_space_capacity = read_only_space_->Capacity(); *stats->new_space_size = new_space_->Size(); *stats->new_space_capacity = new_space_->Capacity(); *stats->old_space_size = old_space_->SizeOfObjects(); *stats->old_space_capacity = old_space_->Capacity(); *stats->code_space_size = code_space_->SizeOfObjects(); *stats->code_space_capacity = code_space_->Capacity(); *stats->map_space_size = map_space_->SizeOfObjects(); *stats->map_space_capacity = map_space_->Capacity(); *stats->lo_space_size = lo_space_->Size(); isolate_->global_handles()->RecordStats(stats); *stats->memory_allocator_size = memory_allocator()->Size(); *stats->memory_allocator_capacity = memory_allocator()->Size() + memory_allocator()->Available(); *stats->os_error = base::OS::GetLastError(); *stats->malloced_memory = isolate_->allocator()->GetCurrentMemoryUsage(); *stats->malloced_peak_memory = isolate_->allocator()->GetMaxMemoryUsage(); if (take_snapshot) { HeapIterator iterator(this); for (HeapObject* obj = iterator.next(); obj != nullptr; obj = iterator.next()) { InstanceType type = obj->map()->instance_type(); DCHECK(0 <= type && type <= LAST_TYPE); stats->objects_per_type[type]++; stats->size_per_type[type] += obj->Size(); } } if (stats->last_few_messages != nullptr) GetFromRingBuffer(stats->last_few_messages); if (stats->js_stacktrace != nullptr) { FixedStringAllocator fixed(stats->js_stacktrace, kStacktraceBufferSize - 1); StringStream accumulator(&fixed, StringStream::kPrintObjectConcise); if (gc_state() == Heap::NOT_IN_GC) { isolate()->PrintStack(&accumulator, Isolate::kPrintStackVerbose); } else { accumulator.Add("Cannot get stack trace in GC."); } } } size_t Heap::OldGenerationSizeOfObjects() { PagedSpaces spaces(this, PagedSpaces::SpacesSpecifier::kAllPagedSpaces); size_t total = 0; for (PagedSpace* space = spaces.next(); space != nullptr; space = spaces.next()) { total += space->SizeOfObjects(); } return total + lo_space_->SizeOfObjects(); } uint64_t Heap::PromotedExternalMemorySize() { if (external_memory_ <= external_memory_at_last_mark_compact_) return 0; return static_cast(external_memory_ - external_memory_at_last_mark_compact_); } bool Heap::ShouldOptimizeForLoadTime() { return isolate()->rail_mode() == PERFORMANCE_LOAD && !AllocationLimitOvershotByLargeMargin() && MonotonicallyIncreasingTimeInMs() < isolate()->LoadStartTimeMs() + kMaxLoadTimeMs; } // This predicate is called when an old generation space cannot allocated from // the free list and is about to add a new page. Returning false will cause a // major GC. It happens when the old generation allocation limit is reached and // - either we need to optimize for memory usage, // - or the incremental marking is not in progress and we cannot start it. bool Heap::ShouldExpandOldGenerationOnSlowAllocation() { if (always_allocate() || OldGenerationSpaceAvailable() > 0) return true; // We reached the old generation allocation limit. if (ShouldOptimizeForMemoryUsage()) return false; if (ShouldOptimizeForLoadTime()) return true; if (incremental_marking()->NeedsFinalization()) { return !AllocationLimitOvershotByLargeMargin(); } if (incremental_marking()->IsStopped() && IncrementalMarkingLimitReached() == IncrementalMarkingLimit::kNoLimit) { // We cannot start incremental marking. return false; } return true; } Heap::HeapGrowingMode Heap::CurrentHeapGrowingMode() { if (ShouldReduceMemory() || FLAG_stress_compaction) { return Heap::HeapGrowingMode::kMinimal; } if (ShouldOptimizeForMemoryUsage()) { return Heap::HeapGrowingMode::kConservative; } if (memory_reducer()->ShouldGrowHeapSlowly()) { return Heap::HeapGrowingMode::kSlow; } return Heap::HeapGrowingMode::kDefault; } // This function returns either kNoLimit, kSoftLimit, or kHardLimit. // The kNoLimit means that either incremental marking is disabled or it is too // early to start incremental marking. // The kSoftLimit means that incremental marking should be started soon. // The kHardLimit means that incremental marking should be started immediately. Heap::IncrementalMarkingLimit Heap::IncrementalMarkingLimitReached() { // Code using an AlwaysAllocateScope assumes that the GC state does not // change; that implies that no marking steps must be performed. if (!incremental_marking()->CanBeActivated() || always_allocate()) { // Incremental marking is disabled or it is too early to start. return IncrementalMarkingLimit::kNoLimit; } if (FLAG_stress_incremental_marking) { return IncrementalMarkingLimit::kHardLimit; } if (OldGenerationSizeOfObjects() <= IncrementalMarking::kActivationThreshold) { // Incremental marking is disabled or it is too early to start. return IncrementalMarkingLimit::kNoLimit; } if ((FLAG_stress_compaction && (gc_count_ & 1) != 0) || HighMemoryPressure()) { // If there is high memory pressure or stress testing is enabled, then // start marking immediately. return IncrementalMarkingLimit::kHardLimit; } if (FLAG_stress_marking > 0) { double gained_since_last_gc = PromotedSinceLastGC() + (external_memory_ - external_memory_at_last_mark_compact_); double size_before_gc = OldGenerationObjectsAndPromotedExternalMemorySize() - gained_since_last_gc; double bytes_to_limit = old_generation_allocation_limit_ - size_before_gc; if (bytes_to_limit > 0) { double current_percent = (gained_since_last_gc / bytes_to_limit) * 100.0; if (FLAG_trace_stress_marking) { isolate()->PrintWithTimestamp( "[IncrementalMarking] %.2lf%% of the memory limit reached\n", current_percent); } if (FLAG_fuzzer_gc_analysis) { // Skips values >=100% since they already trigger marking. if (current_percent < 100.0) { max_marking_limit_reached_ = std::max(max_marking_limit_reached_, current_percent); } } else if (static_cast(current_percent) >= stress_marking_percentage_) { stress_marking_percentage_ = NextStressMarkingLimit(); return IncrementalMarkingLimit::kHardLimit; } } } size_t old_generation_space_available = OldGenerationSpaceAvailable(); if (old_generation_space_available > new_space_->Capacity()) { return IncrementalMarkingLimit::kNoLimit; } if (ShouldOptimizeForMemoryUsage()) { return IncrementalMarkingLimit::kHardLimit; } if (ShouldOptimizeForLoadTime()) { return IncrementalMarkingLimit::kNoLimit; } if (old_generation_space_available == 0) { return IncrementalMarkingLimit::kHardLimit; } return IncrementalMarkingLimit::kSoftLimit; } void Heap::EnableInlineAllocation() { if (!inline_allocation_disabled_) return; inline_allocation_disabled_ = false; // Update inline allocation limit for new space. new_space()->UpdateInlineAllocationLimit(0); } void Heap::DisableInlineAllocation() { if (inline_allocation_disabled_) return; inline_allocation_disabled_ = true; // Update inline allocation limit for new space. new_space()->UpdateInlineAllocationLimit(0); // Update inline allocation limit for old spaces. PagedSpaces spaces(this); CodeSpaceMemoryModificationScope modification_scope(this); for (PagedSpace* space = spaces.next(); space != nullptr; space = spaces.next()) { space->FreeLinearAllocationArea(); } } HeapObject* Heap::EnsureImmovableCode(HeapObject* heap_object, int object_size) { // Code objects which should stay at a fixed address are allocated either // in the first page of code space, in large object space, or (during // snapshot creation) the containing page is marked as immovable. DCHECK(heap_object); DCHECK(code_space_->Contains(heap_object)); DCHECK_GE(object_size, 0); if (!Heap::IsImmovable(heap_object)) { if (isolate()->serializer_enabled() || code_space_->first_page()->Contains(heap_object->address())) { MemoryChunk::FromAddress(heap_object->address())->MarkNeverEvacuate(); } else { // Discard the first code allocation, which was on a page where it could // be moved. CreateFillerObjectAt(heap_object->address(), object_size, ClearRecordedSlots::kNo); heap_object = AllocateRawCodeInLargeObjectSpace(object_size); UnprotectAndRegisterMemoryChunk(heap_object); ZapCodeObject(heap_object->address(), object_size); OnAllocationEvent(heap_object, object_size); } } return heap_object; } HeapObject* Heap::AllocateRawWithLightRetry(int size, AllocationSpace space, AllocationAlignment alignment) { HeapObject* result; AllocationResult alloc = AllocateRaw(size, space, alignment); if (alloc.To(&result)) { DCHECK(result != ReadOnlyRoots(this).exception()); return result; } // Two GCs before panicking. In newspace will almost always succeed. for (int i = 0; i < 2; i++) { CollectGarbage(alloc.RetrySpace(), GarbageCollectionReason::kAllocationFailure); alloc = AllocateRaw(size, space, alignment); if (alloc.To(&result)) { DCHECK(result != ReadOnlyRoots(this).exception()); return result; } } return nullptr; } HeapObject* Heap::AllocateRawWithRetryOrFail(int size, AllocationSpace space, AllocationAlignment alignment) { AllocationResult alloc; HeapObject* result = AllocateRawWithLightRetry(size, space, alignment); if (result) return result; isolate()->counters()->gc_last_resort_from_handles()->Increment(); CollectAllAvailableGarbage(GarbageCollectionReason::kLastResort); { AlwaysAllocateScope scope(isolate()); alloc = AllocateRaw(size, space, alignment); } if (alloc.To(&result)) { DCHECK(result != ReadOnlyRoots(this).exception()); return result; } // TODO(1181417): Fix this. FatalProcessOutOfMemory("CALL_AND_RETRY_LAST"); return nullptr; } // TODO(jkummerow): Refactor this. AllocateRaw should take an "immovability" // parameter and just do what's necessary. HeapObject* Heap::AllocateRawCodeInLargeObjectSpace(int size) { AllocationResult alloc = lo_space()->AllocateRaw(size, EXECUTABLE); HeapObject* result; if (alloc.To(&result)) { DCHECK(result != ReadOnlyRoots(this).exception()); return result; } // Two GCs before panicking. for (int i = 0; i < 2; i++) { CollectGarbage(alloc.RetrySpace(), GarbageCollectionReason::kAllocationFailure); alloc = lo_space()->AllocateRaw(size, EXECUTABLE); if (alloc.To(&result)) { DCHECK(result != ReadOnlyRoots(this).exception()); return result; } } isolate()->counters()->gc_last_resort_from_handles()->Increment(); CollectAllAvailableGarbage(GarbageCollectionReason::kLastResort); { AlwaysAllocateScope scope(isolate()); alloc = lo_space()->AllocateRaw(size, EXECUTABLE); } if (alloc.To(&result)) { DCHECK(result != ReadOnlyRoots(this).exception()); return result; } // TODO(1181417): Fix this. FatalProcessOutOfMemory("CALL_AND_RETRY_LAST"); return nullptr; } void Heap::SetUp() { #ifdef V8_ENABLE_ALLOCATION_TIMEOUT allocation_timeout_ = NextAllocationTimeout(); #endif // Initialize heap spaces and initial maps and objects. // // If the heap is not yet configured (e.g. through the API), configure it. // Configuration is based on the flags new-space-size (really the semispace // size) and old-space-size if set or the initial values of semispace_size_ // and old_generation_size_ otherwise. if (!configured_) ConfigureHeapDefault(); mmap_region_base_ = reinterpret_cast(v8::internal::GetRandomMmapAddr()) & ~kMmapRegionMask; // Set up memory allocator. memory_allocator_ = new MemoryAllocator(isolate_, MaxReserved(), code_range_size_); store_buffer_ = new StoreBuffer(this); heap_controller_ = new HeapController(this); mark_compact_collector_ = new MarkCompactCollector(this); scavenger_collector_ = new ScavengerCollector(this); incremental_marking_ = new IncrementalMarking(this, mark_compact_collector_->marking_worklist(), mark_compact_collector_->weak_objects()); if (FLAG_concurrent_marking) { MarkCompactCollector::MarkingWorklist* marking_worklist = mark_compact_collector_->marking_worklist(); concurrent_marking_ = new ConcurrentMarking( this, marking_worklist->shared(), marking_worklist->bailout(), marking_worklist->on_hold(), mark_compact_collector_->weak_objects(), marking_worklist->embedder()); } else { concurrent_marking_ = new ConcurrentMarking(this, nullptr, nullptr, nullptr, nullptr, nullptr); } for (int i = FIRST_SPACE; i <= LAST_SPACE; i++) { space_[i] = nullptr; } space_[RO_SPACE] = read_only_space_ = new ReadOnlySpace(this); space_[NEW_SPACE] = new_space_ = new NewSpace(this, memory_allocator_->data_page_allocator(), initial_semispace_size_, max_semi_space_size_); space_[OLD_SPACE] = old_space_ = new OldSpace(this); space_[CODE_SPACE] = code_space_ = new CodeSpace(this); space_[MAP_SPACE] = map_space_ = new MapSpace(this); space_[LO_SPACE] = lo_space_ = new LargeObjectSpace(this); space_[NEW_LO_SPACE] = new_lo_space_ = new NewLargeObjectSpace(this); for (int i = 0; i < static_cast(v8::Isolate::kUseCounterFeatureCount); i++) { deferred_counters_[i] = 0; } tracer_ = new GCTracer(this); #ifdef ENABLE_MINOR_MC minor_mark_compact_collector_ = new MinorMarkCompactCollector(this); #else minor_mark_compact_collector_ = nullptr; #endif // ENABLE_MINOR_MC array_buffer_collector_ = new ArrayBufferCollector(this); gc_idle_time_handler_ = new GCIdleTimeHandler(); memory_reducer_ = new MemoryReducer(this); if (V8_UNLIKELY(FLAG_gc_stats)) { live_object_stats_ = new ObjectStats(this); dead_object_stats_ = new ObjectStats(this); } scavenge_job_ = new ScavengeJob(); local_embedder_heap_tracer_ = new LocalEmbedderHeapTracer(isolate()); LOG(isolate_, IntPtrTEvent("heap-capacity", Capacity())); LOG(isolate_, IntPtrTEvent("heap-available", Available())); store_buffer()->SetUp(); mark_compact_collector()->SetUp(); #ifdef ENABLE_MINOR_MC if (minor_mark_compact_collector() != nullptr) { minor_mark_compact_collector()->SetUp(); } #endif // ENABLE_MINOR_MC idle_scavenge_observer_ = new IdleScavengeObserver( *this, ScavengeJob::kBytesAllocatedBeforeNextIdleTask); new_space()->AddAllocationObserver(idle_scavenge_observer_); SetGetExternallyAllocatedMemoryInBytesCallback( DefaultGetExternallyAllocatedMemoryInBytesCallback); if (FLAG_stress_marking > 0) { stress_marking_percentage_ = NextStressMarkingLimit(); stress_marking_observer_ = new StressMarkingObserver(*this); AddAllocationObserversToAllSpaces(stress_marking_observer_, stress_marking_observer_); } if (FLAG_stress_scavenge > 0) { stress_scavenge_observer_ = new StressScavengeObserver(*this); new_space()->AddAllocationObserver(stress_scavenge_observer_); } write_protect_code_memory_ = FLAG_write_protect_code_memory; external_reference_table_.Init(isolate_); } void Heap::InitializeHashSeed() { uint64_t new_hash_seed; if (FLAG_hash_seed == 0) { int64_t rnd = isolate()->random_number_generator()->NextInt64(); new_hash_seed = static_cast(rnd); } else { new_hash_seed = static_cast(FLAG_hash_seed); } hash_seed()->copy_in(0, reinterpret_cast(&new_hash_seed), kInt64Size); } void Heap::SetStackLimits() { DCHECK_NOT_NULL(isolate_); DCHECK(isolate_ == isolate()); // On 64 bit machines, pointers are generally out of range of Smis. We write // something that looks like an out of range Smi to the GC. // Set up the special root array entries containing the stack limits. // These are actually addresses, but the tag makes the GC ignore it. roots_[RootIndex::kStackLimit] = reinterpret_cast( (isolate_->stack_guard()->jslimit() & ~kSmiTagMask) | kSmiTag); roots_[RootIndex::kRealStackLimit] = reinterpret_cast( (isolate_->stack_guard()->real_jslimit() & ~kSmiTagMask) | kSmiTag); } void Heap::ClearStackLimits() { roots_[RootIndex::kStackLimit] = Smi::kZero; roots_[RootIndex::kRealStackLimit] = Smi::kZero; } int Heap::NextAllocationTimeout(int current_timeout) { if (FLAG_random_gc_interval > 0) { // If current timeout hasn't reached 0 the GC was caused by something // different than --stress-atomic-gc flag and we don't update the timeout. if (current_timeout <= 0) { return isolate()->fuzzer_rng()->NextInt(FLAG_random_gc_interval + 1); } else { return current_timeout; } } return FLAG_gc_interval; } void Heap::PrintAllocationsHash() { uint32_t hash = StringHasher::GetHashCore(raw_allocations_hash_); PrintF("\n### Allocations = %u, hash = 0x%08x\n", allocations_count(), hash); } void Heap::PrintMaxMarkingLimitReached() { PrintF("\n### Maximum marking limit reached = %.02lf\n", max_marking_limit_reached_); } void Heap::PrintMaxNewSpaceSizeReached() { PrintF("\n### Maximum new space size reached = %.02lf\n", stress_scavenge_observer_->MaxNewSpaceSizeReached()); } int Heap::NextStressMarkingLimit() { return isolate()->fuzzer_rng()->NextInt(FLAG_stress_marking + 1); } void Heap::NotifyDeserializationComplete() { PagedSpaces spaces(this); for (PagedSpace* s = spaces.next(); s != nullptr; s = spaces.next()) { if (isolate()->snapshot_available()) s->ShrinkImmortalImmovablePages(); #ifdef DEBUG // All pages right after bootstrapping must be marked as never-evacuate. for (Page* p : *s) { DCHECK(p->NeverEvacuate()); } #endif // DEBUG } read_only_space()->MarkAsReadOnly(); deserialization_complete_ = true; } void Heap::SetEmbedderHeapTracer(EmbedderHeapTracer* tracer) { DCHECK_EQ(gc_state_, HeapState::NOT_IN_GC); local_embedder_heap_tracer()->SetRemoteTracer(tracer); } EmbedderHeapTracer* Heap::GetEmbedderHeapTracer() const { return local_embedder_heap_tracer()->remote_tracer(); } void Heap::TracePossibleWrapper(JSObject* js_object) { DCHECK(js_object->IsApiWrapper()); if (js_object->GetEmbedderFieldCount() >= 2 && js_object->GetEmbedderField(0) && js_object->GetEmbedderField(0) != ReadOnlyRoots(this).undefined_value() && js_object->GetEmbedderField(1) != ReadOnlyRoots(this).undefined_value()) { DCHECK_EQ(0, reinterpret_cast(js_object->GetEmbedderField(0)) % 2); local_embedder_heap_tracer()->AddWrapperToTrace(std::pair( reinterpret_cast(js_object->GetEmbedderField(0)), reinterpret_cast(js_object->GetEmbedderField(1)))); } } void Heap::RegisterExternallyReferencedObject(Object** object) { // The embedder is not aware of whether numbers are materialized as heap // objects are just passed around as Smis. if (!(*object)->IsHeapObject()) return; HeapObject* heap_object = HeapObject::cast(*object); DCHECK(Contains(heap_object)); if (FLAG_incremental_marking_wrappers && incremental_marking()->IsMarking()) { incremental_marking()->WhiteToGreyAndPush(heap_object); } else { DCHECK(mark_compact_collector()->in_use()); mark_compact_collector()->MarkExternallyReferencedObject(heap_object); } } void Heap::StartTearDown() { SetGCState(TEAR_DOWN); } void Heap::TearDown() { DCHECK_EQ(gc_state_, TEAR_DOWN); #ifdef VERIFY_HEAP if (FLAG_verify_heap) { Verify(); } #endif UpdateMaximumCommitted(); if (FLAG_verify_predictable || FLAG_fuzzer_gc_analysis) { PrintAllocationsHash(); } if (FLAG_fuzzer_gc_analysis) { if (FLAG_stress_marking > 0) { PrintMaxMarkingLimitReached(); } if (FLAG_stress_scavenge > 0) { PrintMaxNewSpaceSizeReached(); } } new_space()->RemoveAllocationObserver(idle_scavenge_observer_); delete idle_scavenge_observer_; idle_scavenge_observer_ = nullptr; if (FLAG_stress_marking > 0) { RemoveAllocationObserversFromAllSpaces(stress_marking_observer_, stress_marking_observer_); delete stress_marking_observer_; stress_marking_observer_ = nullptr; } if (FLAG_stress_scavenge > 0) { new_space()->RemoveAllocationObserver(stress_scavenge_observer_); delete stress_scavenge_observer_; stress_scavenge_observer_ = nullptr; } if (heap_controller_ != nullptr) { delete heap_controller_; heap_controller_ = nullptr; } if (mark_compact_collector_ != nullptr) { mark_compact_collector_->TearDown(); delete mark_compact_collector_; mark_compact_collector_ = nullptr; } #ifdef ENABLE_MINOR_MC if (minor_mark_compact_collector_ != nullptr) { minor_mark_compact_collector_->TearDown(); delete minor_mark_compact_collector_; minor_mark_compact_collector_ = nullptr; } #endif // ENABLE_MINOR_MC if (scavenger_collector_ != nullptr) { delete scavenger_collector_; scavenger_collector_ = nullptr; } if (array_buffer_collector_ != nullptr) { delete array_buffer_collector_; array_buffer_collector_ = nullptr; } delete incremental_marking_; incremental_marking_ = nullptr; delete concurrent_marking_; concurrent_marking_ = nullptr; delete gc_idle_time_handler_; gc_idle_time_handler_ = nullptr; if (memory_reducer_ != nullptr) { memory_reducer_->TearDown(); delete memory_reducer_; memory_reducer_ = nullptr; } if (live_object_stats_ != nullptr) { delete live_object_stats_; live_object_stats_ = nullptr; } if (dead_object_stats_ != nullptr) { delete dead_object_stats_; dead_object_stats_ = nullptr; } delete local_embedder_heap_tracer_; local_embedder_heap_tracer_ = nullptr; delete scavenge_job_; scavenge_job_ = nullptr; isolate_->global_handles()->TearDown(); external_string_table_.TearDown(); // Tear down all ArrayBuffers before tearing down the heap since their // byte_length may be a HeapNumber which is required for freeing the backing // store. ArrayBufferTracker::TearDown(this); delete tracer_; tracer_ = nullptr; for (int i = FIRST_SPACE; i <= LAST_SPACE; i++) { delete space_[i]; space_[i] = nullptr; } store_buffer()->TearDown(); memory_allocator()->TearDown(); StrongRootsList* next = nullptr; for (StrongRootsList* list = strong_roots_list_; list; list = next) { next = list->next; delete list; } strong_roots_list_ = nullptr; delete store_buffer_; store_buffer_ = nullptr; delete memory_allocator_; memory_allocator_ = nullptr; } void Heap::AddGCPrologueCallback(v8::Isolate::GCCallbackWithData callback, GCType gc_type, void* data) { DCHECK_NOT_NULL(callback); DCHECK(gc_prologue_callbacks_.end() == std::find(gc_prologue_callbacks_.begin(), gc_prologue_callbacks_.end(), GCCallbackTuple(callback, gc_type, data))); gc_prologue_callbacks_.emplace_back(callback, gc_type, data); } void Heap::RemoveGCPrologueCallback(v8::Isolate::GCCallbackWithData callback, void* data) { DCHECK_NOT_NULL(callback); for (size_t i = 0; i < gc_prologue_callbacks_.size(); i++) { if (gc_prologue_callbacks_[i].callback == callback && gc_prologue_callbacks_[i].data == data) { gc_prologue_callbacks_[i] = gc_prologue_callbacks_.back(); gc_prologue_callbacks_.pop_back(); return; } } UNREACHABLE(); } void Heap::AddGCEpilogueCallback(v8::Isolate::GCCallbackWithData callback, GCType gc_type, void* data) { DCHECK_NOT_NULL(callback); DCHECK(gc_epilogue_callbacks_.end() == std::find(gc_epilogue_callbacks_.begin(), gc_epilogue_callbacks_.end(), GCCallbackTuple(callback, gc_type, data))); gc_epilogue_callbacks_.emplace_back(callback, gc_type, data); } void Heap::RemoveGCEpilogueCallback(v8::Isolate::GCCallbackWithData callback, void* data) { DCHECK_NOT_NULL(callback); for (size_t i = 0; i < gc_epilogue_callbacks_.size(); i++) { if (gc_epilogue_callbacks_[i].callback == callback && gc_epilogue_callbacks_[i].data == data) { gc_epilogue_callbacks_[i] = gc_epilogue_callbacks_.back(); gc_epilogue_callbacks_.pop_back(); return; } } UNREACHABLE(); } namespace { Handle CompactWeakArrayList(Heap* heap, Handle array, PretenureFlag pretenure) { if (array->length() == 0) { return array; } int new_length = array->CountLiveWeakReferences(); if (new_length == array->length()) { return array; } Handle new_array = WeakArrayList::EnsureSpace( heap->isolate(), handle(ReadOnlyRoots(heap).empty_weak_array_list(), heap->isolate()), new_length, pretenure); // Allocation might have caused GC and turned some of the elements into // cleared weak heap objects. Count the number of live references again and // fill in the new array. int copy_to = 0; for (int i = 0; i < array->length(); i++) { MaybeObject* element = array->Get(i); if (element->IsCleared()) continue; new_array->Set(copy_to++, element); } new_array->set_length(copy_to); return new_array; } } // anonymous namespace void Heap::CompactWeakArrayLists(PretenureFlag pretenure) { // Find known PrototypeUsers and compact them. std::vector> prototype_infos; { HeapIterator iterator(this); for (HeapObject* o = iterator.next(); o != nullptr; o = iterator.next()) { if (o->IsPrototypeInfo()) { PrototypeInfo* prototype_info = PrototypeInfo::cast(o); if (prototype_info->prototype_users()->IsWeakArrayList()) { prototype_infos.emplace_back(handle(prototype_info, isolate())); } } } } for (auto& prototype_info : prototype_infos) { Handle array( WeakArrayList::cast(prototype_info->prototype_users()), isolate()); DCHECK_IMPLIES(pretenure == TENURED, InOldSpace(*array) || *array == ReadOnlyRoots(this).empty_weak_array_list()); WeakArrayList* new_array = PrototypeUsers::Compact( array, this, JSObject::PrototypeRegistryCompactionCallback, pretenure); prototype_info->set_prototype_users(new_array); } // Find known WeakArrayLists and compact them. Handle scripts(script_list(), isolate()); DCHECK_IMPLIES(pretenure == TENURED, InOldSpace(*scripts)); scripts = CompactWeakArrayList(this, scripts, pretenure); set_script_list(*scripts); Handle no_script_list(noscript_shared_function_infos(), isolate()); DCHECK_IMPLIES(pretenure == TENURED, InOldSpace(*no_script_list)); no_script_list = CompactWeakArrayList(this, no_script_list, pretenure); set_noscript_shared_function_infos(*no_script_list); } void Heap::AddRetainedMap(Handle map) { if (map->is_in_retained_map_list()) { return; } Handle array(retained_maps(), isolate()); if (array->IsFull()) { CompactRetainedMaps(*array); } array = WeakArrayList::AddToEnd(isolate(), array, MaybeObjectHandle::Weak(map)); array = WeakArrayList::AddToEnd( isolate(), array, MaybeObjectHandle(Smi::FromInt(FLAG_retain_maps_for_n_gc), isolate())); if (*array != retained_maps()) { set_retained_maps(*array); } map->set_is_in_retained_map_list(true); } void Heap::CompactRetainedMaps(WeakArrayList* retained_maps) { DCHECK_EQ(retained_maps, this->retained_maps()); int length = retained_maps->length(); int new_length = 0; int new_number_of_disposed_maps = 0; // This loop compacts the array by removing cleared weak cells. for (int i = 0; i < length; i += 2) { MaybeObject* maybe_object = retained_maps->Get(i); if (maybe_object->IsCleared()) { continue; } DCHECK(maybe_object->IsWeak()); MaybeObject* age = retained_maps->Get(i + 1); DCHECK(age->IsSmi()); if (i != new_length) { retained_maps->Set(new_length, maybe_object); retained_maps->Set(new_length + 1, age); } if (i < number_of_disposed_maps_) { new_number_of_disposed_maps += 2; } new_length += 2; } number_of_disposed_maps_ = new_number_of_disposed_maps; HeapObject* undefined = ReadOnlyRoots(this).undefined_value(); for (int i = new_length; i < length; i++) { retained_maps->Set(i, HeapObjectReference::Strong(undefined)); } if (new_length != length) retained_maps->set_length(new_length); } void Heap::FatalProcessOutOfMemory(const char* location) { v8::internal::V8::FatalProcessOutOfMemory(isolate(), location, true); } #ifdef DEBUG class PrintHandleVisitor : public RootVisitor { public: void VisitRootPointers(Root root, const char* description, Object** start, Object** end) override { for (Object** p = start; p < end; p++) PrintF(" handle %p to %p\n", reinterpret_cast(p), reinterpret_cast(*p)); } }; void Heap::PrintHandles() { PrintF("Handles:\n"); PrintHandleVisitor v; isolate_->handle_scope_implementer()->Iterate(&v); } #endif class CheckHandleCountVisitor : public RootVisitor { public: CheckHandleCountVisitor() : handle_count_(0) {} ~CheckHandleCountVisitor() override { CHECK_GT(HandleScope::kCheckHandleThreshold, handle_count_); } void VisitRootPointers(Root root, const char* description, Object** start, Object** end) override { handle_count_ += end - start; } private: ptrdiff_t handle_count_; }; void Heap::CheckHandleCount() { CheckHandleCountVisitor v; isolate_->handle_scope_implementer()->Iterate(&v); } Address* Heap::store_buffer_top_address() { return store_buffer()->top_address(); } // static intptr_t Heap::store_buffer_mask_constant() { return StoreBuffer::kStoreBufferMask; } // static Address Heap::store_buffer_overflow_function_address() { return FUNCTION_ADDR(StoreBuffer::StoreBufferOverflow); } void Heap::ClearRecordedSlot(HeapObject* object, Object** slot) { Address slot_addr = reinterpret_cast
(slot); Page* page = Page::FromAddress(slot_addr); if (!page->InNewSpace()) { DCHECK_EQ(page->owner()->identity(), OLD_SPACE); store_buffer()->DeleteEntry(slot_addr); } } #ifdef DEBUG void Heap::VerifyClearedSlot(HeapObject* object, Object** slot) { if (InNewSpace(object)) return; Address slot_addr = reinterpret_cast
(slot); Page* page = Page::FromAddress(slot_addr); DCHECK_EQ(page->owner()->identity(), OLD_SPACE); store_buffer()->MoveAllEntriesToRememberedSet(); CHECK(!RememberedSet::Contains(page, slot_addr)); // Old to old slots are filtered with invalidated slots. CHECK_IMPLIES(RememberedSet::Contains(page, slot_addr), page->RegisteredObjectWithInvalidatedSlots(object)); } #endif void Heap::ClearRecordedSlotRange(Address start, Address end) { Page* page = Page::FromAddress(start); if (!page->InNewSpace()) { DCHECK_EQ(page->owner()->identity(), OLD_SPACE); store_buffer()->DeleteEntry(start, end); } } PagedSpace* PagedSpaces::next() { switch (counter_++) { case RO_SPACE: // skip NEW_SPACE counter_++; return heap_->read_only_space(); case OLD_SPACE: return heap_->old_space(); case CODE_SPACE: return heap_->code_space(); case MAP_SPACE: return heap_->map_space(); default: return nullptr; } } SpaceIterator::SpaceIterator(Heap* heap) : heap_(heap), current_space_(FIRST_SPACE - 1) {} SpaceIterator::~SpaceIterator() = default; bool SpaceIterator::has_next() { // Iterate until no more spaces. return current_space_ != LAST_SPACE; } Space* SpaceIterator::next() { DCHECK(has_next()); return heap_->space(++current_space_); } class HeapObjectsFilter { public: virtual ~HeapObjectsFilter() = default; virtual bool SkipObject(HeapObject* object) = 0; }; class UnreachableObjectsFilter : public HeapObjectsFilter { public: explicit UnreachableObjectsFilter(Heap* heap) : heap_(heap) { MarkReachableObjects(); } ~UnreachableObjectsFilter() override { for (auto it : reachable_) { delete it.second; it.second = nullptr; } } bool SkipObject(HeapObject* object) override { if (object->IsFiller()) return true; MemoryChunk* chunk = MemoryChunk::FromAddress(object->address()); if (reachable_.count(chunk) == 0) return true; return reachable_[chunk]->count(object) == 0; } private: bool MarkAsReachable(HeapObject* object) { MemoryChunk* chunk = MemoryChunk::FromAddress(object->address()); if (reachable_.count(chunk) == 0) { reachable_[chunk] = new std::unordered_set(); } if (reachable_[chunk]->count(object)) return false; reachable_[chunk]->insert(object); return true; } class MarkingVisitor : public ObjectVisitor, public RootVisitor { public: explicit MarkingVisitor(UnreachableObjectsFilter* filter) : filter_(filter) {} void VisitPointers(HeapObject* host, Object** start, Object** end) override { MarkPointers(reinterpret_cast(start), reinterpret_cast(end)); } void VisitPointers(HeapObject* host, MaybeObject** start, MaybeObject** end) final { MarkPointers(start, end); } void VisitRootPointers(Root root, const char* description, Object** start, Object** end) override { MarkPointers(reinterpret_cast(start), reinterpret_cast(end)); } void TransitiveClosure() { while (!marking_stack_.empty()) { HeapObject* obj = marking_stack_.back(); marking_stack_.pop_back(); obj->Iterate(this); } } private: void MarkPointers(MaybeObject** start, MaybeObject** end) { // Treat weak references as strong. for (MaybeObject** p = start; p < end; p++) { HeapObject* heap_object; if ((*p)->GetHeapObject(&heap_object)) { if (filter_->MarkAsReachable(heap_object)) { marking_stack_.push_back(heap_object); } } } } UnreachableObjectsFilter* filter_; std::vector marking_stack_; }; friend class MarkingVisitor; void MarkReachableObjects() { MarkingVisitor visitor(this); heap_->IterateRoots(&visitor, VISIT_ALL_BUT_READ_ONLY); visitor.TransitiveClosure(); } Heap* heap_; DisallowHeapAllocation no_allocation_; std::unordered_map*> reachable_; }; HeapIterator::HeapIterator(Heap* heap, HeapIterator::HeapObjectsFiltering filtering) : no_heap_allocation_(), heap_(heap), filtering_(filtering), filter_(nullptr), space_iterator_(nullptr), object_iterator_(nullptr) { heap_->MakeHeapIterable(); heap_->heap_iterator_start(); // Start the iteration. space_iterator_ = new SpaceIterator(heap_); switch (filtering_) { case kFilterUnreachable: filter_ = new UnreachableObjectsFilter(heap_); break; default: break; } object_iterator_ = space_iterator_->next()->GetObjectIterator(); } HeapIterator::~HeapIterator() { heap_->heap_iterator_end(); #ifdef DEBUG // Assert that in filtering mode we have iterated through all // objects. Otherwise, heap will be left in an inconsistent state. if (filtering_ != kNoFiltering) { DCHECK_NULL(object_iterator_); } #endif delete space_iterator_; delete filter_; } HeapObject* HeapIterator::next() { if (filter_ == nullptr) return NextObject(); HeapObject* obj = NextObject(); while ((obj != nullptr) && (filter_->SkipObject(obj))) obj = NextObject(); return obj; } HeapObject* HeapIterator::NextObject() { // No iterator means we are done. if (object_iterator_.get() == nullptr) return nullptr; if (HeapObject* obj = object_iterator_.get()->Next()) { // If the current iterator has more objects we are fine. return obj; } else { // Go though the spaces looking for one that has objects. while (space_iterator_->has_next()) { object_iterator_ = space_iterator_->next()->GetObjectIterator(); if (HeapObject* obj = object_iterator_.get()->Next()) { return obj; } } } // Done with the last space. object_iterator_.reset(nullptr); return nullptr; } void Heap::UpdateTotalGCTime(double duration) { if (FLAG_trace_gc_verbose) { total_gc_time_ms_ += duration; } } void Heap::ExternalStringTable::CleanUpNewSpaceStrings() { int last = 0; Isolate* isolate = heap_->isolate(); for (size_t i = 0; i < new_space_strings_.size(); ++i) { Object* o = new_space_strings_[i]; if (o->IsTheHole(isolate)) { continue; } // The real external string is already in one of these vectors and was or // will be processed. Re-processing it will add a duplicate to the vector. if (o->IsThinString()) continue; DCHECK(o->IsExternalString()); if (InNewSpace(o)) { new_space_strings_[last++] = o; } else { old_space_strings_.push_back(o); } } new_space_strings_.resize(last); } void Heap::ExternalStringTable::CleanUpAll() { CleanUpNewSpaceStrings(); int last = 0; Isolate* isolate = heap_->isolate(); for (size_t i = 0; i < old_space_strings_.size(); ++i) { Object* o = old_space_strings_[i]; if (o->IsTheHole(isolate)) { continue; } // The real external string is already in one of these vectors and was or // will be processed. Re-processing it will add a duplicate to the vector. if (o->IsThinString()) continue; DCHECK(o->IsExternalString()); DCHECK(!InNewSpace(o)); old_space_strings_[last++] = o; } old_space_strings_.resize(last); #ifdef VERIFY_HEAP if (FLAG_verify_heap) { Verify(); } #endif } void Heap::ExternalStringTable::TearDown() { for (size_t i = 0; i < new_space_strings_.size(); ++i) { Object* o = new_space_strings_[i]; // Dont finalize thin strings. if (o->IsThinString()) continue; heap_->FinalizeExternalString(ExternalString::cast(o)); } new_space_strings_.clear(); for (size_t i = 0; i < old_space_strings_.size(); ++i) { Object* o = old_space_strings_[i]; // Dont finalize thin strings. if (o->IsThinString()) continue; heap_->FinalizeExternalString(ExternalString::cast(o)); } old_space_strings_.clear(); } void Heap::RememberUnmappedPage(Address page, bool compacted) { // Tag the page pointer to make it findable in the dump file. if (compacted) { page ^= 0xC1EAD & (Page::kPageSize - 1); // Cleared. } else { page ^= 0x1D1ED & (Page::kPageSize - 1); // I died. } remembered_unmapped_pages_[remembered_unmapped_pages_index_] = page; remembered_unmapped_pages_index_++; remembered_unmapped_pages_index_ %= kRememberedUnmappedPages; } void Heap::RegisterStrongRoots(Object** start, Object** end) { StrongRootsList* list = new StrongRootsList(); list->next = strong_roots_list_; list->start = start; list->end = end; strong_roots_list_ = list; } void Heap::UnregisterStrongRoots(Object** start) { StrongRootsList* prev = nullptr; StrongRootsList* list = strong_roots_list_; while (list != nullptr) { StrongRootsList* next = list->next; if (list->start == start) { if (prev) { prev->next = next; } else { strong_roots_list_ = next; } delete list; } else { prev = list; } list = next; } } void Heap::SetBuiltinsConstantsTable(FixedArray* cache) { set_builtins_constants_table(cache); } size_t Heap::NumberOfTrackedHeapObjectTypes() { return ObjectStats::OBJECT_STATS_COUNT; } size_t Heap::ObjectCountAtLastGC(size_t index) { if (live_object_stats_ == nullptr || index >= ObjectStats::OBJECT_STATS_COUNT) return 0; return live_object_stats_->object_count_last_gc(index); } size_t Heap::ObjectSizeAtLastGC(size_t index) { if (live_object_stats_ == nullptr || index >= ObjectStats::OBJECT_STATS_COUNT) return 0; return live_object_stats_->object_size_last_gc(index); } bool Heap::GetObjectTypeName(size_t index, const char** object_type, const char** object_sub_type) { if (index >= ObjectStats::OBJECT_STATS_COUNT) return false; switch (static_cast(index)) { #define COMPARE_AND_RETURN_NAME(name) \ case name: \ *object_type = #name; \ *object_sub_type = ""; \ return true; INSTANCE_TYPE_LIST(COMPARE_AND_RETURN_NAME) #undef COMPARE_AND_RETURN_NAME #define COMPARE_AND_RETURN_NAME(name) \ case ObjectStats::FIRST_VIRTUAL_TYPE + ObjectStats::name: \ *object_type = #name; \ *object_sub_type = ""; \ return true; VIRTUAL_INSTANCE_TYPE_LIST(COMPARE_AND_RETURN_NAME) #undef COMPARE_AND_RETURN_NAME } return false; } size_t Heap::NumberOfNativeContexts() { int result = 0; Object* context = native_contexts_list(); while (!context->IsUndefined(isolate())) { ++result; Context* native_context = Context::cast(context); context = native_context->next_context_link(); } return result; } size_t Heap::NumberOfDetachedContexts() { // The detached_contexts() array has two entries per detached context. return detached_contexts()->length() / 2; } const char* AllocationSpaceName(AllocationSpace space) { switch (space) { case NEW_SPACE: return "NEW_SPACE"; case OLD_SPACE: return "OLD_SPACE"; case CODE_SPACE: return "CODE_SPACE"; case MAP_SPACE: return "MAP_SPACE"; case LO_SPACE: return "LO_SPACE"; case NEW_LO_SPACE: return "NEW_LO_SPACE"; case RO_SPACE: return "RO_SPACE"; default: UNREACHABLE(); } return nullptr; } void VerifyPointersVisitor::VisitPointers(HeapObject* host, Object** start, Object** end) { VerifyPointers(host, reinterpret_cast(start), reinterpret_cast(end)); } void VerifyPointersVisitor::VisitPointers(HeapObject* host, MaybeObject** start, MaybeObject** end) { VerifyPointers(host, start, end); } void VerifyPointersVisitor::VisitRootPointers(Root root, const char* description, Object** start, Object** end) { VerifyPointers(nullptr, reinterpret_cast(start), reinterpret_cast(end)); } void VerifyPointersVisitor::VerifyPointers(HeapObject* host, MaybeObject** start, MaybeObject** end) { for (MaybeObject** current = start; current < end; current++) { HeapObject* object; if ((*current)->GetHeapObject(&object)) { CHECK(heap_->Contains(object)); CHECK(object->map()->IsMap()); } else { CHECK((*current)->IsSmi() || (*current)->IsCleared()); } } } void VerifySmisVisitor::VisitRootPointers(Root root, const char* description, Object** start, Object** end) { for (Object** current = start; current < end; current++) { CHECK((*current)->IsSmi()); } } bool Heap::AllowedToBeMigrated(HeapObject* obj, AllocationSpace dst) { // Object migration is governed by the following rules: // // 1) Objects in new-space can be migrated to the old space // that matches their target space or they stay in new-space. // 2) Objects in old-space stay in the same space when migrating. // 3) Fillers (two or more words) can migrate due to left-trimming of // fixed arrays in new-space or old space. // 4) Fillers (one word) can never migrate, they are skipped by // incremental marking explicitly to prevent invalid pattern. // // Since this function is used for debugging only, we do not place // asserts here, but check everything explicitly. if (obj->map() == ReadOnlyRoots(this).one_pointer_filler_map()) return false; InstanceType type = obj->map()->instance_type(); MemoryChunk* chunk = MemoryChunk::FromAddress(obj->address()); AllocationSpace src = chunk->owner()->identity(); switch (src) { case NEW_SPACE: return dst == NEW_SPACE || dst == OLD_SPACE; case OLD_SPACE: return dst == OLD_SPACE; case CODE_SPACE: return dst == CODE_SPACE && type == CODE_TYPE; case MAP_SPACE: case LO_SPACE: case NEW_LO_SPACE: case RO_SPACE: return false; } UNREACHABLE(); } void Heap::CreateObjectStats() { if (V8_LIKELY(FLAG_gc_stats == 0)) return; if (!live_object_stats_) { live_object_stats_ = new ObjectStats(this); } if (!dead_object_stats_) { dead_object_stats_ = new ObjectStats(this); } } void AllocationObserver::AllocationStep(int bytes_allocated, Address soon_object, size_t size) { DCHECK_GE(bytes_allocated, 0); bytes_to_next_step_ -= bytes_allocated; if (bytes_to_next_step_ <= 0) { Step(static_cast(step_size_ - bytes_to_next_step_), soon_object, size); step_size_ = GetNextStepSize(); bytes_to_next_step_ = step_size_; } DCHECK_GE(bytes_to_next_step_, 0); } namespace { Map* GcSafeMapOfCodeSpaceObject(HeapObject* object) { MapWord map_word = object->map_word(); return map_word.IsForwardingAddress() ? map_word.ToForwardingAddress()->map() : map_word.ToMap(); } int GcSafeSizeOfCodeSpaceObject(HeapObject* object) { return object->SizeFromMap(GcSafeMapOfCodeSpaceObject(object)); } Code* GcSafeCastToCode(Heap* heap, HeapObject* object, Address inner_pointer) { Code* code = reinterpret_cast(object); DCHECK_NOT_NULL(code); DCHECK(heap->GcSafeCodeContains(code, inner_pointer)); return code; } } // namespace bool Heap::GcSafeCodeContains(HeapObject* code, Address addr) { Map* map = GcSafeMapOfCodeSpaceObject(code); DCHECK(map == ReadOnlyRoots(this).code_map()); if (InstructionStream::TryLookupCode(isolate(), addr) == code) return true; Address start = code->address(); Address end = code->address() + code->SizeFromMap(map); return start <= addr && addr < end; } Code* Heap::GcSafeFindCodeForInnerPointer(Address inner_pointer) { Code* code = InstructionStream::TryLookupCode(isolate(), inner_pointer); if (code != nullptr) return code; // Check if the inner pointer points into a large object chunk. LargePage* large_page = lo_space()->FindPage(inner_pointer); if (large_page != nullptr) { return GcSafeCastToCode(this, large_page->GetObject(), inner_pointer); } DCHECK(code_space()->Contains(inner_pointer)); // Iterate through the page until we reach the end or find an object starting // after the inner pointer. Page* page = Page::FromAddress(inner_pointer); DCHECK_EQ(page->owner(), code_space()); mark_compact_collector()->sweeper()->EnsurePageIsIterable(page); Address addr = page->skip_list()->StartFor(inner_pointer); Address top = code_space()->top(); Address limit = code_space()->limit(); while (true) { if (addr == top && addr != limit) { addr = limit; continue; } HeapObject* obj = HeapObject::FromAddress(addr); int obj_size = GcSafeSizeOfCodeSpaceObject(obj); Address next_addr = addr + obj_size; if (next_addr > inner_pointer) return GcSafeCastToCode(this, obj, inner_pointer); addr = next_addr; } } void Heap::WriteBarrierForCodeSlow(Code* code) { for (RelocIterator it(code, RelocInfo::ModeMask(RelocInfo::EMBEDDED_OBJECT)); !it.done(); it.next()) { GenerationalBarrierForCode(code, it.rinfo(), it.rinfo()->target_object()); MarkingBarrierForCode(code, it.rinfo(), it.rinfo()->target_object()); } } void Heap::GenerationalBarrierSlow(HeapObject* object, Address slot, HeapObject* value) { Heap* heap = Heap::FromWritableHeapObject(object); heap->store_buffer()->InsertEntry(slot); } void Heap::GenerationalBarrierForElementsSlow(Heap* heap, FixedArray* array, int offset, int length) { for (int i = 0; i < length; i++) { if (!InNewSpace(array->get(offset + i))) continue; heap->store_buffer()->InsertEntry( reinterpret_cast
(array->RawFieldOfElementAt(offset + i))); } } void Heap::GenerationalBarrierForCodeSlow(Code* host, RelocInfo* rinfo, HeapObject* object) { DCHECK(InNewSpace(object)); Page* source_page = Page::FromAddress(reinterpret_cast
(host)); RelocInfo::Mode rmode = rinfo->rmode(); Address addr = rinfo->pc(); SlotType slot_type = SlotTypeForRelocInfoMode(rmode); if (rinfo->IsInConstantPool()) { addr = rinfo->constant_pool_entry_address(); if (RelocInfo::IsCodeTargetMode(rmode)) { slot_type = CODE_ENTRY_SLOT; } else { DCHECK(RelocInfo::IsEmbeddedObject(rmode)); slot_type = OBJECT_SLOT; } } RememberedSet::InsertTyped( source_page, reinterpret_cast
(host), slot_type, addr); } void Heap::MarkingBarrierSlow(HeapObject* object, Address slot, HeapObject* value) { Heap* heap = Heap::FromWritableHeapObject(object); heap->incremental_marking()->RecordWriteSlow( object, reinterpret_cast(slot), value); } void Heap::MarkingBarrierForElementsSlow(Heap* heap, HeapObject* object) { if (FLAG_concurrent_marking || heap->incremental_marking()->marking_state()->IsBlack(object)) { heap->incremental_marking()->RevisitObject(object); } } void Heap::MarkingBarrierForCodeSlow(Code* host, RelocInfo* rinfo, HeapObject* object) { Heap* heap = Heap::FromWritableHeapObject(host); DCHECK(heap->incremental_marking()->IsMarking()); heap->incremental_marking()->RecordWriteIntoCode(host, rinfo, object); } bool Heap::PageFlagsAreConsistent(HeapObject* object) { Heap* heap = Heap::FromWritableHeapObject(object); MemoryChunk* chunk = MemoryChunk::FromHeapObject(object); heap_internals::MemoryChunk* slim_chunk = heap_internals::MemoryChunk::FromHeapObject(object); const bool generation_consistency = chunk->owner()->identity() != NEW_SPACE || (chunk->InNewSpace() && slim_chunk->InNewSpace()); const bool marking_consistency = !heap->incremental_marking()->IsMarking() || (chunk->IsFlagSet(MemoryChunk::INCREMENTAL_MARKING) && slim_chunk->IsMarking()); return generation_consistency && marking_consistency; } static_assert(MemoryChunk::Flag::INCREMENTAL_MARKING == heap_internals::MemoryChunk::kMarkingBit, "Incremental marking flag inconsistent"); static_assert(MemoryChunk::Flag::IN_FROM_SPACE == heap_internals::MemoryChunk::kFromSpaceBit, "From space flag inconsistent"); static_assert(MemoryChunk::Flag::IN_TO_SPACE == heap_internals::MemoryChunk::kToSpaceBit, "To space flag inconsistent"); static_assert(MemoryChunk::kFlagsOffset == heap_internals::MemoryChunk::kFlagsOffset, "Flag offset inconsistent"); void Heap::SetEmbedderStackStateForNextFinalizaton( EmbedderHeapTracer::EmbedderStackState stack_state) { local_embedder_heap_tracer()->SetEmbedderStackStateForNextFinalization( stack_state); } } // namespace internal } // namespace v8