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chromium / v8 / v8 / f2414988ee6d08844e35eaa49669337a41c29491 / . / src / heap / heap.cc
blob: 91fccd90b128c64ada00c8d9956b7107480e48aa [file] [log] [blame]
// 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 <unordered_map>
#include <unordered_set>
#include "src/accessors.h"
#include "src/api.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/codegen.h"
#include "src/compilation-cache.h"
#include "src/compiler-dispatcher/optimizing-compile-dispatcher.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-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/incremental-marking.h"
#include "src/heap/item-parallel-job.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/interpreter/interpreter.h"
#include "src/objects/object-macros.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/trap-handler/trap-handler.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"
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) {
// TODO(tebbi): Remove second half of DCHECK once
// FLAG_harmony_restrict_constructor_return is gone.
DCHECK(construct_stub_create_deopt_pc_offset() == Smi::kZero ||
construct_stub_create_deopt_pc_offset() == Smi::FromInt(pc_offset));
set_construct_stub_create_deopt_pc_offset(Smi::FromInt(pc_offset));
}
void Heap::SetConstructStubInvokeDeoptPCOffset(int pc_offset) {
// TODO(tebbi): Remove second half of DCHECK once
// FLAG_harmony_restrict_constructor_return is gone.
DCHECK(construct_stub_invoke_deopt_pc_offset() == Smi::kZero ||
construct_stub_invoke_deopt_pc_offset() == Smi::FromInt(pc_offset));
set_construct_stub_invoke_deopt_pc_offset(Smi::FromInt(pc_offset));
}
void Heap::SetGetterStubDeoptPCOffset(int pc_offset) {
DCHECK_EQ(Smi::kZero, getter_stub_deopt_pc_offset());
set_getter_stub_deopt_pc_offset(Smi::FromInt(pc_offset));
}
void Heap::SetSetterStubDeoptPCOffset(int pc_offset) {
DCHECK_EQ(Smi::kZero, setter_stub_deopt_pc_offset());
set_setter_stub_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::SetSerializedTemplates(FixedArray* templates) {
DCHECK_EQ(empty_fixed_array(), serialized_templates());
DCHECK(isolate()->serializer_enabled());
set_serialized_templates(templates);
}
void Heap::SetSerializedGlobalProxySizes(FixedArray* sizes) {
DCHECK_EQ(empty_fixed_array(), serialized_global_proxy_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) {
callback = other.callback;
gc_type = other.gc_type;
data = other.data;
return *this;
}
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()
: external_memory_(0),
external_memory_limit_(kExternalAllocationSoftLimit),
external_memory_at_last_mark_compact_(0),
isolate_(nullptr),
code_range_size_(0),
// semispace_size_ should be a power of 2 and old_generation_size_ should
// be a multiple of Page::kPageSize.
max_semi_space_size_(8 * (kPointerSize / 4) * MB),
initial_semispace_size_(kMinSemiSpaceSizeInKB * KB),
max_old_generation_size_(700ul * (kPointerSize / 4) * MB),
initial_max_old_generation_size_(max_old_generation_size_),
initial_old_generation_size_(max_old_generation_size_ /
kInitalOldGenerationLimitFactor),
old_generation_size_configured_(false),
// Variables set based on semispace_size_ and old_generation_size_ in
// ConfigureHeap.
// Will be 4 * reserved_semispace_size_ to ensure that young
// generation can be aligned to its size.
maximum_committed_(0),
survived_since_last_expansion_(0),
survived_last_scavenge_(0),
always_allocate_scope_count_(0),
memory_pressure_level_(MemoryPressureLevel::kNone),
out_of_memory_callback_(nullptr),
out_of_memory_callback_data_(nullptr),
contexts_disposed_(0),
number_of_disposed_maps_(0),
new_space_(nullptr),
old_space_(NULL),
code_space_(NULL),
map_space_(NULL),
lo_space_(NULL),
gc_state_(NOT_IN_GC),
gc_post_processing_depth_(0),
allocations_count_(0),
raw_allocations_hash_(0),
ms_count_(0),
gc_count_(0),
mmap_region_base_(0),
remembered_unmapped_pages_index_(0),
#ifdef DEBUG
allocation_timeout_(0),
#endif // DEBUG
old_generation_allocation_limit_(initial_old_generation_size_),
inline_allocation_disabled_(false),
tracer_(nullptr),
promoted_objects_size_(0),
promotion_ratio_(0),
semi_space_copied_object_size_(0),
previous_semi_space_copied_object_size_(0),
semi_space_copied_rate_(0),
nodes_died_in_new_space_(0),
nodes_copied_in_new_space_(0),
nodes_promoted_(0),
maximum_size_scavenges_(0),
last_idle_notification_time_(0.0),
last_gc_time_(0.0),
mark_compact_collector_(nullptr),
minor_mark_compact_collector_(nullptr),
memory_allocator_(nullptr),
store_buffer_(nullptr),
incremental_marking_(nullptr),
concurrent_marking_(nullptr),
gc_idle_time_handler_(nullptr),
memory_reducer_(nullptr),
live_object_stats_(nullptr),
dead_object_stats_(nullptr),
scavenge_job_(nullptr),
parallel_scavenge_semaphore_(0),
idle_scavenge_observer_(nullptr),
new_space_allocation_counter_(0),
old_generation_allocation_counter_at_last_gc_(0),
old_generation_size_at_last_gc_(0),
global_pretenuring_feedback_(kInitialFeedbackCapacity),
is_marking_flag_(false),
ring_buffer_full_(false),
ring_buffer_end_(0),
configured_(false),
current_gc_flags_(Heap::kNoGCFlags),
current_gc_callback_flags_(GCCallbackFlags::kNoGCCallbackFlags),
external_string_table_(this),
gc_callbacks_depth_(0),
deserialization_complete_(false),
strong_roots_list_(NULL),
heap_iterator_depth_(0),
local_embedder_heap_tracer_(nullptr),
fast_promotion_mode_(false),
use_tasks_(true),
force_oom_(false),
delay_sweeper_tasks_for_testing_(false),
pending_layout_change_object_(nullptr) {
// Ensure old_generation_size_ is a multiple of kPageSize.
DCHECK_EQ(0, max_old_generation_size_ & (Page::kPageSize - 1));
memset(roots_, 0, sizeof(roots_[0]) * kRootListLength);
set_native_contexts_list(NULL);
set_allocation_sites_list(Smi::kZero);
set_encountered_weak_collections(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(NULL, false);
}
size_t Heap::Capacity() {
if (!HasBeenSetUp()) return 0;
return new_space_->Capacity() + OldGenerationCapacity();
}
size_t Heap::OldGenerationCapacity() {
if (!HasBeenSetUp()) return 0;
return old_space_->Capacity() + code_space_->Capacity() +
map_space_->Capacity() + lo_space_->SizeOfObjects();
}
size_t Heap::CommittedOldGenerationMemory() {
if (!HasBeenSetUp()) return 0;
return old_space_->CommittedMemory() + code_space_->CommittedMemory() +
map_space_->CommittedMemory() + lo_space_->Size();
}
size_t Heap::CommittedMemory() {
if (!HasBeenSetUp()) return 0;
return new_space_->CommittedMemory() + CommittedOldGenerationMemory();
}
size_t Heap::CommittedPhysicalMemory() {
if (!HasBeenSetUp()) return 0;
return new_space_->CommittedPhysicalMemory() +
old_space_->CommittedPhysicalMemory() +
code_space_->CommittedPhysicalMemory() +
map_space_->CommittedPhysicalMemory() +
lo_space_->CommittedPhysicalMemory();
}
size_t Heap::CommittedMemoryExecutable() {
if (!HasBeenSetUp()) return 0;
return static_cast<size_t>(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;
AllSpaces spaces(this);
for (Space* space = spaces.next(); space != NULL; space = spaces.next()) {
total += space->Available();
}
return total;
}
bool Heap::HasBeenSetUp() {
return old_space_ != NULL && code_space_ != NULL && map_space_ != NULL &&
lo_space_ != NULL;
}
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;
}
// Is there enough space left in OLD to guarantee that a scavenge can
// succeed?
//
// Note that MemoryAllocator->MaxAvailable() undercounts the memory available
// for object promotion. It counts only the bytes that the memory
// allocator has not yet allocated from the OS and assigned to any space,
// and does not count available bytes already in the old space or code
// space. Undercounting is safe---we may get an unrequested full GC when
// a scavenge would have succeeded.
if (memory_allocator()->MaxAvailable() <= new_space_->Size()) {
isolate_->counters()
->gc_compactor_caused_by_oldspace_exhaustion()
->Increment();
*reason = "scavenge might not succeed";
return MARK_COMPACTOR;
}
// Default
*reason = NULL;
return YoungGenerationCollector();
}
void Heap::SetGCState(HeapState state) {
gc_state_ = state;
}
// TODO(1238405): Combine the infrastructure for --heap-stats and
// --log-gc to avoid the complicated preprocessor and flag testing.
void Heap::ReportStatisticsBeforeGC() {
// Heap::ReportHeapStatistics will also log NewSpace statistics when
// compiled --log-gc is set. The following logic is used to avoid
// double logging.
#ifdef DEBUG
if (FLAG_heap_stats || FLAG_log_gc) new_space_->CollectStatistics();
if (FLAG_heap_stats) {
ReportHeapStatistics("Before GC");
} else if (FLAG_log_gc) {
new_space_->ReportStatistics();
}
if (FLAG_heap_stats || FLAG_log_gc) new_space_->ClearHistograms();
#else
if (FLAG_log_gc) {
new_space_->CollectStatistics();
new_space_->ReportStatistics();
new_space_->ClearHistograms();
}
#endif // DEBUG
}
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_, "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_, "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_, "External memory reported: %6" PRId64 " KB\n",
external_memory_ / 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_);
}
// TODO(1238405): Combine the infrastructure for --heap-stats and
// --log-gc to avoid the complicated preprocessor and flag testing.
void Heap::ReportStatisticsAfterGC() {
// Similar to the before GC, we use some complicated logic to ensure that
// NewSpace statistics are logged exactly once when --log-gc is turned on.
#if defined(DEBUG)
if (FLAG_heap_stats) {
new_space_->CollectStatistics();
ReportHeapStatistics("After GC");
} else if (FLAG_log_gc) {
new_space_->ReportStatistics();
}
#else
if (FLAG_log_gc) new_space_->ReportStatistics();
#endif // DEBUG
for (int i = 0; i < static_cast<int>(v8::Isolate::kUseCounterFeatureCount);
++i) {
int count = deferred_counters_[i];
deferred_counters_[i] = 0;
while (count > 0) {
count--;
isolate()->CountUsage(static_cast<v8::Isolate::UseCounterFeature>(i));
}
}
}
void Heap::AddRetainingPathTarget(Handle<HeapObject> object) {
if (!FLAG_track_retaining_path) {
PrintF("Retaining path tracking requires --trace-retaining-path\n");
} else {
Handle<WeakFixedArray> array = WeakFixedArray::Add(
handle(retaining_path_targets(), isolate()), object);
set_retaining_path_targets(*array);
}
}
bool Heap::IsRetainingPathTarget(HeapObject* object) {
WeakFixedArray::Iterator it(retaining_path_targets());
HeapObject* target;
while ((target = it.Next<HeapObject>()) != nullptr) {
if (target == object) return true;
}
return false;
}
namespace {
const char* RootToString(Root root) {
switch (root) {
#define ROOT_CASE(root_id, ignore, description) \
case Root::root_id: \
return description;
ROOT_ID_LIST(ROOT_CASE)
#undef ROOT_CASE
case Root::kCodeFlusher:
return "(Code flusher)";
case Root::kPartialSnapshotCache:
return "(Partial snapshot cache)";
case Root::kWeakCollections:
return "(Weak collections)";
case Root::kWrapperTracing:
return "(Wrapper tracing)";
case Root::kUnknown:
return "(Unknown)";
}
UNREACHABLE();
return nullptr;
}
} // namespace
void Heap::PrintRetainingPath(HeapObject* target) {
PrintF("\n\n\n");
PrintF("#################################################\n");
PrintF("Retaining path for %p:\n", static_cast<void*>(target));
HeapObject* object = target;
std::vector<HeapObject*> retaining_path;
Root root = Root::kUnknown;
while (true) {
retaining_path.push_back(object);
if (retainer_.count(object)) {
object = retainer_[object];
} else {
if (retaining_root_.count(object)) {
root = retaining_root_[object];
}
break;
}
}
int distance = static_cast<int>(retaining_path.size());
for (auto object : retaining_path) {
PrintF("\n");
PrintF("^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n");
PrintF("Distance from root %d: ", distance);
object->ShortPrint();
PrintF("\n");
#ifdef OBJECT_PRINT
object->Print();
PrintF("\n");
#endif
--distance;
}
PrintF("\n");
PrintF("^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n");
PrintF("Root: %s\n", RootToString(root));
PrintF("-------------------------------------------------\n");
}
void Heap::AddRetainer(HeapObject* retainer, HeapObject* object) {
retainer_[object] = retainer;
if (IsRetainingPathTarget(object)) {
PrintRetainingPath(object);
}
}
void Heap::AddRetainingRoot(Root root, HeapObject* object) {
retaining_root_[object] = root;
if (IsRetainingPathTarget(object)) {
PrintRetainingPath(object);
}
}
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();
ReportStatisticsBeforeGC();
#endif // DEBUG
if (new_space_->IsAtMaximumCapacity()) {
maximum_size_scavenges_++;
} else {
maximum_size_scavenges_ = 0;
}
CheckNewSpaceExpansionCriteria();
UpdateNewSpaceAllocationCounter();
if (FLAG_track_retaining_path) {
retainer_.clear();
retaining_root_.clear();
}
}
size_t Heap::SizeOfObjects() {
size_t total = 0;
AllSpaces spaces(this);
for (Space* space = spaces.next(); space != NULL; space = spaces.next()) {
total += space->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";
default:
UNREACHABLE();
}
return nullptr;
}
void Heap::SetRootCodeStubs(UnseededNumberDictionary* value) {
roots_[kCodeStubsRootIndex] = value;
}
void Heap::RepairFreeListsAfterDeserialization() {
PagedSpaces spaces(this);
for (PagedSpace* space = spaces.next(); space != NULL;
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<int>(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));
}
}
}
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<double>(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<void*>(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) {
Object* list_element = allocation_sites_list();
while (list_element->IsAllocationSite()) {
site = AllocationSite::cast(list_element);
DCHECK(site->IsAllocationSite());
allocation_sites++;
if (site->IsMaybeTenure()) {
site->set_deopt_dependent_code(true);
trigger_deoptimization = true;
}
list_element = site->weak_next();
}
}
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::DeoptMarkedAllocationSites() {
// TODO(hpayer): If iterating over the allocation sites list becomes a
// performance issue, use a cache data structure in heap instead.
Object* list_element = allocation_sites_list();
while (list_element->IsAllocationSite()) {
AllocationSite* site = AllocationSite::cast(list_element);
if (site->deopt_dependent_code()) {
site->dependent_code()->MarkCodeForDeoptimization(
isolate_, DependentCode::kAllocationSiteTenuringChangedGroup);
site->set_deopt_dependent_code(false);
}
list_element = site->weak_next();
}
Deoptimizer::DeoptimizeMarkedCode(isolate_);
}
void Heap::GarbageCollectionEpilogue() {
TRACE_GC(tracer(), GCTracer::Scope::HEAP_EPILOGUE);
// In release mode, we only zap the from space under heap verification.
if (Heap::ShouldZapGarbage()) {
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<int>(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<int>(100 - (SizeOfObjects() * 100.0) / CommittedMemory()));
isolate_->counters()->heap_sample_total_committed()->AddSample(
static_cast<int>(CommittedMemory() / KB));
isolate_->counters()->heap_sample_total_used()->AddSample(
static_cast<int>(SizeOfObjects() / KB));
isolate_->counters()->heap_sample_map_space_committed()->AddSample(
static_cast<int>(map_space()->CommittedMemory() / KB));
isolate_->counters()->heap_sample_code_space_committed()->AddSample(
static_cast<int>(code_space()->CommittedMemory() / KB));
isolate_->counters()->heap_sample_maximum_committed()->AddSample(
static_cast<int>(MaximumCommittedMemory() / KB));
}
#define UPDATE_COUNTERS_FOR_SPACE(space) \
isolate_->counters()->space##_bytes_available()->Set( \
static_cast<int>(space()->Available())); \
isolate_->counters()->space##_bytes_committed()->Set( \
static_cast<int>(space()->CommittedMemory())); \
isolate_->counters()->space##_bytes_used()->Set( \
static_cast<int>(space()->SizeOfObjects()));
#define UPDATE_FRAGMENTATION_FOR_SPACE(space) \
if (space()->CommittedMemory() > 0) { \
isolate_->counters()->external_fragmentation_##space()->AddSample( \
static_cast<int>(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
// Remember the last top pointer so that we can later find out
// whether we allocated in new space since the last GC.
new_space_top_after_last_gc_ = new_space()->top();
last_gc_time_ = MonotonicallyIncreasingTimeInMs();
{
TRACE_GC(tracer(), GCTracer::Scope::HEAP_EPILOGUE_REDUCE_NEW_SPACE);
ReduceNewSpaceSize();
}
}
void Heap::PreprocessStackTraces() {
WeakFixedArray::Iterator iterator(weak_stack_trace_list());
FixedArray* elements;
while ((elements = iterator.Next<FixedArray>()) != nullptr) {
for (int j = 1; j < elements->length(); j += 4) {
Object* maybe_code = elements->get(j + 2);
// If GC happens while adding a stack trace to the weak fixed array,
// which has been copied into a larger backing store, we may run into
// a stack trace that has already been preprocessed. Guard against this.
if (!maybe_code->IsAbstractCode()) break;
AbstractCode* abstract_code = AbstractCode::cast(maybe_code);
int offset = Smi::ToInt(elements->get(j + 3));
int pos = abstract_code->SourcePosition(offset);
elements->set(j + 2, Smi::FromInt(pos));
}
}
// We must not compact the weak fixed list here, as we may be in the middle
// of writing to it, when the GC triggered. Instead, we reset the root value.
set_weak_stack_trace_list(Smi::kZero);
}
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 (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();
FinalizeIncrementalMarking(
GarbageCollectionReason::kFinalizeMarkingViaStackGuard);
}
}
void Heap::ScheduleIdleScavengeIfNeeded(int bytes_allocated) {
scavenge_job_->ScheduleIdleTaskIfNeeded(this, bytes_allocated);
}
void Heap::FinalizeIncrementalMarking(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<EXTERNAL> 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<EXTERNAL> state(isolate_);
HandleScope handle_scope(isolate_);
CallGCEpilogueCallbacks(kGCTypeIncrementalMarking, kNoGCCallbackFlags);
}
}
}
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);
}
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) {
InvokeOutOfMemoryCallback();
}
RuntimeCallTimerScope runtime_timer(
isolate(), &RuntimeCallStats::GC_Custom_AllAvailableGarbage);
if (isolate()->concurrent_recompilation_enabled()) {
// The optimizing compiler may be unnecessarily holding on to memory.
DisallowHeapAllocation no_recursive_gc;
isolate()->optimizing_compile_dispatcher()->Flush(
OptimizingCompileDispatcher::BlockingBehavior::kDontBlock);
}
isolate()->ClearSerializerData();
set_current_gc_flags(kMakeHeapIterableMask | kReduceMemoryFootprintMask);
isolate_->compilation_cache()->Clear();
const int kMaxNumberOfAttempts = 7;
const int kMinNumberOfAttempts = 2;
for (int attempt = 0; attempt < kMaxNumberOfAttempts; attempt++) {
if (!CollectGarbage(OLD_SPACE, gc_reason,
v8::kGCCallbackFlagCollectAllAvailableGarbage) &&
attempt + 1 >= kMinNumberOfAttempts) {
break;
}
}
set_current_gc_flags(kNoGCFlags);
new_space_->Shrink();
UncommitFromSpace();
}
void Heap::ReportExternalMemoryPressure() {
const GCCallbackFlags kGCCallbackFlagsForExternalMemory =
static_cast<GCCallbackFlags>(
kGCCallbackFlagSynchronousPhantomCallbackProcessing |
kGCCallbackFlagCollectAllExternalMemory);
if (external_memory_ >
(external_memory_at_last_mark_compact_ + external_memory_hard_limit())) {
CollectAllGarbage(
kReduceMemoryFootprintMask | kFinalizeIncrementalMarkingMask,
GarbageCollectionReason::kExternalMemoryPressure,
static_cast<GCCallbackFlags>(kGCCallbackFlagCollectAllAvailableGarbage |
kGCCallbackFlagsForExternalMemory));
return;
}
if (incremental_marking()->IsStopped()) {
if (incremental_marking()->CanBeActivated()) {
StartIncrementalMarking(i::Heap::kNoGCFlags,
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<double>(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<GCCallbackFlags>(
current_gc_callback_flags_ | kGCCallbackFlagsForExternalMemory);
incremental_marking()->AdvanceIncrementalMarking(
deadline, IncrementalMarking::GC_VIA_STACK_GUARD,
IncrementalMarking::FORCE_COMPLETION, 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<int>(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) {
// The VM is in the GC state until exiting this function.
VMState<GC> state(isolate());
const char* collector_reason = NULL;
GarbageCollector collector = SelectGarbageCollector(space, &collector_reason);
#ifdef DEBUG
// Reset the allocation timeout to the GC interval, 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.
allocation_timeout_ = Max(6, FLAG_gc_interval);
#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());
next_gc_likely_to_collect_more =
PerformGarbageCollection(collector, gc_callback_flags);
}
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 = PromotedSpaceSizeOfObjects();
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);
}
memory_pressure_level_.SetValue(MemoryPressureLevel::kNone);
}
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. The heap snapshot
// generator needs incremental marking to stay off after it aborted.
// We do this only for scavenger to avoid a loop where mark-compact
// causes another mark-compact.
if (IsYoungGenerationCollector(collector) &&
!ShouldAbortIncrementalMarking()) {
StartIncrementalMarkingIfAllocationLimitIsReached(
kNoGCFlags, 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);
}
if (isolate()->concurrent_recompilation_enabled()) {
// Flush the queued recompilation tasks.
isolate()->optimizing_compile_dispatcher()->Flush(
OptimizingCompileDispatcher::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) {
if (len == 0) return;
DCHECK(array->map() != 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);
}
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:
void VisitPointers(HeapObject* host, Object** start, Object** end) override {
// Visit all HeapObject pointers in [start, end).
for (Object** p = start; p < end; p++) {
if ((*p)->IsHeapObject()) {
HeapObject* object = HeapObject::cast(*p);
Isolate* isolate = object->GetIsolate();
// Check that the string is actually internalized.
CHECK(object->IsTheHole(isolate) || object->IsUndefined(isolate) ||
object->IsInternalizedString());
}
}
}
};
static void VerifyStringTable(Heap* heap) {
StringTableVerifier verifier;
heap->string_table()->IterateElements(&verifier);
}
#endif // VERIFY_HEAP
bool Heap::ReserveSpace(Reservation* reservations, std::vector<Address>* maps) {
bool gc_performed = true;
int counter = 0;
static const int kThreshold = 20;
while (gc_performed && counter++ < kThreshold) {
gc_performed = false;
for (int space = NEW_SPACE; space < SerializerDeserializer::kNumberOfSpaces;
space++) {
Reservation* reservation = &reservations[space];
DCHECK_LE(1, reservation->size());
if (reservation->at(0).size == 0) 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_t>(size),
MemoryAllocator::PageAreaSize(
static_cast<AllocationSpace>(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) {
if (space == NEW_SPACE) {
CollectGarbage(NEW_SPACE, GarbageCollectionReason::kDeserializer);
} else {
if (counter > 1) {
CollectAllGarbage(
kReduceMemoryFootprintMask | kAbortIncrementalMarkingMask,
GarbageCollectionReason::kDeserializer);
} else {
CollectAllGarbage(kAbortIncrementalMarkingMask,
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.
V8::FatalProcessOutOfMemory("Committing semi space failed.");
}
void Heap::ClearNormalizedMapCaches() {
if (isolate_->bootstrapper()->IsActive() &&
!incremental_marking()->IsMarking()) {
return;
}
Object* context = native_contexts_list();
while (!context->IsUndefined(isolate())) {
// GC can happen when the context is not fully initialized,
// so the cache can be undefined.
Object* cache =
Context::cast(context)->get(Context::NORMALIZED_MAP_CACHE_INDEX);
if (!cache->IsUndefined(isolate())) {
NormalizedMapCache::cast(cache)->Clear();
}
context = Context::cast(context)->next_context_link();
}
}
void Heap::UpdateSurvivalStatistics(int start_new_space_size) {
if (start_new_space_size == 0) return;
promotion_ratio_ = (static_cast<double>(promoted_objects_size_) /
static_cast<double>(start_new_space_size) * 100);
if (previous_semi_space_copied_object_size_ > 0) {
promotion_rate_ =
(static_cast<double>(promoted_objects_size_) /
static_cast<double>(previous_semi_space_copied_object_size_) * 100);
} else {
promotion_rate_ = 0;
}
semi_space_copied_rate_ =
(static_cast<double>(semi_space_copied_object_size_) /
static_cast<double>(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);
}
#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<EXTERNAL> state(isolate_);
HandleScope handle_scope(isolate_);
CallGCPrologueCallbacks(gc_type, kNoGCCallbackFlags);
}
}
EnsureFromSpaceIsCommitted();
int start_new_space_size = static_cast<int>(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<size_t>(promoted_objects_size_);
old_generation_size_at_last_gc_ = PromotedSpaceSizeOfObjects();
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(start_new_space_size);
ConfigureInitialOldGenerationSize();
if (!fast_promotion_mode_ || collector == MARK_COMPACTOR) {
ComputeFastPromotionMode(promotion_ratio_ + semi_space_copied_rate_);
}
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(this);
// Update relocatables.
Relocatable::PostGarbageCollectionProcessing(isolate_);
double gc_speed = tracer()->CombinedMarkCompactSpeedInBytesPerMillisecond();
double mutator_speed =
tracer()->CurrentOldGenerationAllocationThroughputInBytesPerMillisecond();
size_t old_gen_size = PromotedSpaceSizeOfObjects();
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;
SetOldGenerationAllocationLimit(old_gen_size, gc_speed, mutator_speed);
} else if (HasLowYoungGenerationAllocationRate() &&
old_generation_size_configured_) {
DampenOldGenerationAllocationLimit(old_gen_size, gc_speed, mutator_speed);
}
{
GCCallbacksScope scope(this);
if (scope.CheckReenter()) {
AllowHeapAllocation allow_allocation;
TRACE_GC(tracer(), GCTracer::Scope::HEAP_EXTERNAL_EPILOGUE);
VMState<EXTERNAL> state(isolate_);
HandleScope handle_scope(isolate_);
CallGCEpilogueCallbacks(gc_type, gc_callback_flags);
}
}
#ifdef VERIFY_HEAP
if (FLAG_verify_heap) {
VerifyStringTable(this);
}
#endif
return freed_global_handles > 0;
}
void Heap::CallGCPrologueCallbacks(GCType gc_type, GCCallbackFlags flags) {
RuntimeCallTimerScope runtime_timer(isolate(),
&RuntimeCallStats::GCPrologueCallback);
for (const GCCallbackTuple& info : gc_prologue_callbacks_) {
if (gc_type & info.gc_type) {
v8::Isolate* isolate = reinterpret_cast<v8::Isolate*>(this->isolate());
info.callback(isolate, gc_type, flags, info.data);
}
}
}
void Heap::CallGCEpilogueCallbacks(GCType gc_type, GCCallbackFlags flags) {
RuntimeCallTimerScope runtime_timer(isolate(),
&RuntimeCallStats::GCEpilogueCallback);
for (const GCCallbackTuple& info : gc_epilogue_callbacks_) {
if (gc_type & info.gc_type) {
v8::Isolate* isolate = reinterpret_cast<v8::Isolate*>(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();
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() {
DCHECK(FLAG_minor_mc);
SetGCState(MINOR_MARK_COMPACT);
LOG(isolate_, ResourceEvent("MinorMarkCompact", "begin"));
TRACE_GC(tracer(), GCTracer::Scope::MINOR_MC);
AlwaysAllocateScope always_allocate(isolate());
PauseAllocationObserversScope pause_observers(this);
IncrementalMarking::PauseBlackAllocationScope pause_black_allocation(
incremental_marking());
minor_mark_compact_collector()->CollectGarbage();
LOG(isolate_, ResourceEvent("MinorMarkCompact", "end"));
SetGCState(NOT_IN_GC);
}
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();
PreprocessStackTraces();
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();
ClearNormalizedMapCaches();
}
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;
}
}
static bool IsUnscavengedHeapObject(Heap* heap, Object** p) {
return heap->InNewSpace(*p) &&
!HeapObject::cast(*p)->map_word().IsForwardingAddress();
}
class ScavengeWeakObjectRetainer : public WeakObjectRetainer {
public:
explicit ScavengeWeakObjectRetainer(Heap* heap) : heap_(heap) {}
virtual Object* RetainAs(Object* object) {
if (!heap_->InFromSpace(object)) {
return object;
}
MapWord map_word = HeapObject::cast(object)->map_word();
if (map_word.IsForwardingAddress()) {
return map_word.ToForwardingAddress();
}
return NULL;
}
private:
Heap* heap_;
};
void Heap::EvacuateYoungGeneration() {
TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_FAST_PROMOTE);
base::LockGuard<base::Mutex> 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().EnsureNewSpaceCompleted();
SetGCState(SCAVENGE);
LOG(isolate_, ResourceEvent("scavenge", "begin"));
// Move pages from new->old generation.
PageRange range(new_space()->bottom(), new_space()->top());
for (auto it = range.begin(); it != range.end();) {
Page* p = (*++it)->prev_page();
p->Unlink();
Page::ConvertNewToOld(p);
if (incremental_marking()->IsMarking())
mark_compact_collector()->RecordLiveSlotsOnPage(p);
}
// Reset new space.
if (!new_space()->Rebalance()) {
FatalProcessOutOfMemory("NewSpace::Rebalance");
}
new_space()->ResetAllocationInfo();
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);
}
static bool IsLogging(Isolate* isolate) {
return FLAG_verify_predictable || isolate->logger()->is_logging() ||
isolate->is_profiling() ||
(isolate->heap_profiler() != nullptr &&
isolate->heap_profiler()->is_tracking_object_moves());
}
class ScavengingItem : public ItemParallelJob::Item {
public:
virtual ~ScavengingItem() {}
virtual void Process(Scavenger* scavenger) = 0;
};
class ScavengingTask final : public ItemParallelJob::Task {
public:
ScavengingTask(Heap* heap, Scavenger* scavenger, OneshotBarrier* barrier)
: ItemParallelJob::Task(heap->isolate()),
heap_(heap),
scavenger_(scavenger),
barrier_(barrier) {}
void RunInParallel() final {
double scavenging_time = 0.0;
{
barrier_->Start();
TimedScope scope(&scavenging_time);
ScavengingItem* item = nullptr;
while ((item = GetItem<ScavengingItem>()) != nullptr) {
item->Process(scavenger_);
item->MarkFinished();
}
do {
scavenger_->Process(barrier_);
} while (!barrier_->Wait());
scavenger_->Process();
}
if (FLAG_trace_parallel_scavenge) {
PrintIsolate(heap_->isolate(),
"scavenge[%p]: time=%.2f copied=%zu promoted=%zu\n",
static_cast<void*>(this), scavenging_time,
scavenger_->bytes_copied(), scavenger_->bytes_promoted());
}
};
private:
Heap* const heap_;
Scavenger* const scavenger_;
OneshotBarrier* const barrier_;
};
class PageScavengingItem final : public ScavengingItem {
public:
explicit PageScavengingItem(Heap* heap, MemoryChunk* chunk)
: heap_(heap), chunk_(chunk) {}
virtual ~PageScavengingItem() {}
void Process(Scavenger* scavenger) final {
base::LockGuard<base::RecursiveMutex> guard(chunk_->mutex());
scavenger->AnnounceLockedPage(chunk_);
RememberedSet<OLD_TO_NEW>::Iterate(
chunk_,
[this, scavenger](Address addr) {
return scavenger->CheckAndScavengeObject(heap_, addr);
},
SlotSet::KEEP_EMPTY_BUCKETS);
RememberedSet<OLD_TO_NEW>::IterateTyped(
chunk_,
[this, scavenger](SlotType type, Address host_addr, Address addr) {
return UpdateTypedSlotHelper::UpdateTypedSlot(
heap_->isolate(), type, addr, [this, scavenger](Object** addr) {
// We expect that objects referenced by code are long
// living. If we do not force promotion, then we need to
// clear old_to_new slots in dead code objects after
// mark-compact.
return scavenger->CheckAndScavengeObject(
heap_, reinterpret_cast<Address>(addr));
});
});
}
private:
Heap* const heap_;
MemoryChunk* const chunk_;
};
int Heap::NumberOfScavengeTasks() {
if (!FLAG_parallel_scavenge) return 1;
const int num_scavenge_tasks =
static_cast<int>(new_space()->TotalCapacity()) / MB;
return Max(
1,
Min(Min(num_scavenge_tasks, kMaxScavengerTasks),
static_cast<int>(
V8::GetCurrentPlatform()->NumberOfAvailableBackgroundThreads())));
}
void Heap::Scavenge() {
TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_SCAVENGE);
base::LockGuard<base::Mutex> 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().EnsureNewSpaceCompleted();
SetGCState(SCAVENGE);
// Implements Cheney's copying algorithm
LOG(isolate_, ResourceEvent("scavenge", "begin"));
// Flip the semispaces. After flipping, to space is empty, from space has
// live objects.
new_space_->Flip();
new_space_->ResetAllocationInfo();
ItemParallelJob job(isolate()->cancelable_task_manager(),
&parallel_scavenge_semaphore_);
const int kMainThreadId = 0;
Scavenger* scavengers[kMaxScavengerTasks];
const bool is_logging = IsLogging(isolate());
const int num_scavenge_tasks = NumberOfScavengeTasks();
OneshotBarrier barrier;
Scavenger::CopiedList copied_list(num_scavenge_tasks);
Scavenger::PromotionList promotion_list(num_scavenge_tasks);
for (int i = 0; i < num_scavenge_tasks; i++) {
scavengers[i] =
new Scavenger(this, is_logging, &copied_list, &promotion_list, i);
job.AddTask(new ScavengingTask(this, scavengers[i], &barrier));
}
RememberedSet<OLD_TO_NEW>::IterateMemoryChunks(
this, [this, &job](MemoryChunk* chunk) {
job.AddItem(new PageScavengingItem(this, chunk));
});
RootScavengeVisitor root_scavenge_visitor(this, scavengers[kMainThreadId]);
{
// Identify weak unmodified handles. Requires an unmodified graph.
TRACE_GC(tracer(),
GCTracer::Scope::SCAVENGER_SCAVENGE_WEAK_GLOBAL_HANDLES_IDENTIFY);
isolate()->global_handles()->IdentifyWeakUnmodifiedObjects(
&JSObject::IsUnmodifiedApiObject);
}
{
// Copy roots.
TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_SCAVENGE_ROOTS);
IterateRoots(&root_scavenge_visitor, VISIT_ALL_IN_SCAVENGE);
}
{
// Weak collections are held strongly by the Scavenger.
TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_SCAVENGE_WEAK);
IterateEncounteredWeakCollections(&root_scavenge_visitor);
}
{
// Parallel phase scavenging all copied and promoted objects.
TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_SCAVENGE_PARALLEL);
job.Run();
DCHECK(copied_list.IsGlobalEmpty());
DCHECK(promotion_list.IsGlobalEmpty());
}
{
// Scavenge weak global handles.
TRACE_GC(tracer(),
GCTracer::Scope::SCAVENGER_SCAVENGE_WEAK_GLOBAL_HANDLES_PROCESS);
isolate()->global_handles()->MarkNewSpaceWeakUnmodifiedObjectsPending(
&IsUnscavengedHeapObject);
isolate()->global_handles()->IterateNewSpaceWeakUnmodifiedRoots(
&root_scavenge_visitor);
scavengers[kMainThreadId]->Process();
}
for (int i = 0; i < num_scavenge_tasks; i++) {
scavengers[i]->Finalize();
delete scavengers[i];
}
UpdateNewSpaceReferencesInExternalStringTable(
&UpdateNewSpaceReferenceInExternalStringTableEntry);
incremental_marking()->UpdateMarkingWorklistAfterScavenge();
if (FLAG_concurrent_marking) {
// Ensure that concurrent marker does not track pages that are
// going to be unmapped.
for (Page* p : PageRange(new_space()->FromSpaceStart(),
new_space()->FromSpaceEnd())) {
concurrent_marking()->ClearLiveness(p);
}
}
ScavengeWeakObjectRetainer weak_object_retainer(this);
ProcessYoungWeakReferences(&weak_object_retainer);
// Set age mark.
new_space_->set_age_mark(new_space_->top());
ArrayBufferTracker::FreeDeadInNewSpace(this);
RememberedSet<OLD_TO_NEW>::IterateMemoryChunks(this, [](MemoryChunk* chunk) {
if (chunk->SweepingDone()) {
RememberedSet<OLD_TO_NEW>::FreeEmptyBuckets(chunk);
} else {
RememberedSet<OLD_TO_NEW>::PreFreeEmptyBuckets(chunk);
}
});
// Update how much has survived scavenge.
IncrementYoungSurvivorsCounter(SurvivedNewSpaceObjectSize());
// Scavenger may find new wrappers by iterating objects promoted onto a black
// page.
local_embedder_heap_tracer()->RegisterWrappersWithRemoteTracer();
LOG(isolate_, ResourceEvent("scavenge", "end"));
SetGCState(NOT_IN_GC);
}
void Heap::ComputeFastPromotionMode(double survival_rate) {
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) {
PrintIsolate(
isolate(), "Fast promotion mode: %s survival rate: %" PRIuS "%%\n",
fast_promotion_mode_ ? "true" : "false", survived_in_new_space);
}
}
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 NULL;
}
heap->FinalizeExternalString(string);
return NULL;
}
// String is still reachable.
String* string = String::cast(first_word.ToForwardingAddress());
if (string->IsThinString()) string = ThinString::cast(string)->actual();
// Internalization can replace external strings with non-external strings.
return string->IsExternalString() ? string : nullptr;
}
void Heap::ExternalStringTable::Verify() {
#ifdef DEBUG
for (size_t i = 0; i < new_space_strings_.size(); ++i) {
Object* obj = Object::cast(new_space_strings_[i]);
DCHECK(heap_->InNewSpace(obj));
DCHECK(!obj->IsTheHole(heap_->isolate()));
}
for (size_t i = 0; i < old_space_strings_.size(); ++i) {
Object* obj = Object::cast(old_space_strings_[i]);
DCHECK(!heap_->InNewSpace(obj));
DCHECK(!obj->IsTheHole(heap_->isolate()));
}
#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 == NULL) continue;
DCHECK(target->IsExternalString());
if (heap_->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<size_t>(last - start));
#ifdef VERIFY_HEAP
if (FLAG_verify_heap) {
Verify();
}
#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, 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, 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<Context>(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<AllocationSite>(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::ResetAllAllocationSitesDependentCode(PretenureFlag flag) {
DisallowHeapAllocation no_allocation_scope;
Object* cur = allocation_sites_list();
bool marked = false;
while (cur->IsAllocationSite()) {
AllocationSite* casted = AllocationSite::cast(cur);
if (casted->GetPretenureMode() == flag) {
casted->ResetPretenureDecision();
casted->set_deopt_dependent_code(true);
marked = true;
RemoveAllocationSitePretenuringFeedback(casted);
}
cur = casted->weak_next();
}
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<double>(size_of_objects_after_gc) * 100) /
static_cast<double>(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(
v8::ExternalResourceVisitor* visitor)
: visitor_(visitor) {}
virtual void VisitRootPointers(Root root, Object** start, Object** end) {
for (Object** p = start; p < end; p++) {
DCHECK((*p)->IsExternalString());
visitor_->VisitExternalString(
Utils::ToLocal(Handle<String>(String::cast(*p))));
}
}
private:
v8::ExternalResourceVisitor* visitor_;
} external_string_table_visitor(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) {
intptr_t offset = OffsetFrom(address);
if (alignment == kDoubleAligned && (offset & kDoubleAlignmentMask) != 0)
return kPointerSize;
if (alignment == kDoubleUnaligned && (offset & 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(MinimumAllocationLimitGrowingStep(),
static_cast<size_t>(
static_cast<double>(old_generation_allocation_limit_) *
(tracer()->AverageSurvivalRatio() / 100)));
}
}
AllocationResult Heap::AllocatePartialMap(InstanceType instance_type,
int instance_size) {
Object* result = nullptr;
AllocationResult allocation = AllocateRaw(Map::kSize, MAP_SPACE);
if (!allocation.To(&result)) return allocation;
// Map::cast cannot be used due to uninitialized map field.
Map* map = reinterpret_cast<Map*>(result);
map->set_map_after_allocation(reinterpret_cast<Map*>(root(kMetaMapRootIndex)),
SKIP_WRITE_BARRIER);
map->set_instance_type(instance_type);
map->set_instance_size(instance_size);
// Initialize to only containing tagged fields.
if (FLAG_unbox_double_fields) {
map->set_layout_descriptor(LayoutDescriptor::FastPointerLayout());
}
// GetVisitorId requires a properly initialized LayoutDescriptor.
map->set_visitor_id(Map::GetVisitorId(map));
map->clear_unused();
map->set_inobject_properties_or_constructor_function_index(0);
map->set_unused_property_fields(0);
map->set_bit_field(0);
map->set_bit_field2(0);
int bit_field3 = Map::EnumLengthBits::encode(kInvalidEnumCacheSentinel) |
Map::OwnsDescriptors::encode(true) |
Map::ConstructionCounter::encode(Map::kNoSlackTracking);
map->set_bit_field3(bit_field3);
map->set_weak_cell_cache(Smi::kZero);
return map;
}
AllocationResult Heap::AllocateMap(InstanceType instance_type,
int instance_size,
ElementsKind elements_kind) {
HeapObject* result = nullptr;
AllocationResult allocation = AllocateRaw(Map::kSize, MAP_SPACE);
if (!allocation.To(&result)) return allocation;
isolate()->counters()->maps_created()->Increment();
result->set_map_after_allocation(meta_map(), SKIP_WRITE_BARRIER);
Map* map = Map::cast(result);
map->set_instance_type(instance_type);
map->set_prototype(null_value(), SKIP_WRITE_BARRIER);
map->set_constructor_or_backpointer(null_value(), SKIP_WRITE_BARRIER);
map->set_instance_size(instance_size);
map->clear_unused();
map->set_inobject_properties_or_constructor_function_index(0);
map->set_dependent_code(DependentCode::cast(empty_fixed_array()),
SKIP_WRITE_BARRIER);
map->set_weak_cell_cache(Smi::kZero);
map->set_raw_transitions(Smi::kZero);
map->set_unused_property_fields(0);
map->set_instance_descriptors(empty_descriptor_array());
if (FLAG_unbox_double_fields) {
map->set_layout_descriptor(LayoutDescriptor::FastPointerLayout());
}
// Must be called only after |instance_type|, |instance_size| and
// |layout_descriptor| are set.
map->set_visitor_id(Map::GetVisitorId(map));
map->set_bit_field(0);
map->set_bit_field2(1 << Map::kIsExtensible);
int bit_field3 = Map::EnumLengthBits::encode(kInvalidEnumCacheSentinel) |
Map::OwnsDescriptors::encode(true) |
Map::ConstructionCounter::encode(Map::kNoSlackTracking);
map->set_bit_field3(bit_field3);
map->set_elements_kind(elements_kind);
map->set_new_target_is_base(true);
return map;
}
AllocationResult Heap::AllocateFillerObject(int size, bool double_align,
AllocationSpace space) {
HeapObject* obj = nullptr;
{
AllocationAlignment align = double_align ? kDoubleAligned : kWordAligned;
AllocationResult allocation = AllocateRaw(size, space, align);
if (!allocation.To(&obj)) return allocation;
}
#ifdef DEBUG
MemoryChunk* chunk = MemoryChunk::FromAddress(obj->address());
DCHECK(chunk->owner()->identity() == space);
#endif
CreateFillerObjectAt(obj->address(), size, ClearRecordedSlots::kNo);
return obj;
}
AllocationResult Heap::AllocateHeapNumber(MutableMode mode,
PretenureFlag pretenure) {
// Statically ensure that it is safe to allocate heap numbers in paged
// spaces.
int size = HeapNumber::kSize;
STATIC_ASSERT(HeapNumber::kSize <= kMaxRegularHeapObjectSize);
AllocationSpace space = SelectSpace(pretenure);
HeapObject* result = nullptr;
{
AllocationResult allocation = AllocateRaw(size, space, kDoubleUnaligned);
if (!allocation.To(&result)) return allocation;
}
Map* map = mode == MUTABLE ? mutable_heap_number_map() : heap_number_map();
HeapObject::cast(result)->set_map_after_allocation(map, SKIP_WRITE_BARRIER);
return result;
}
AllocationResult Heap::AllocateBigInt(int length, bool zero_initialize,
PretenureFlag pretenure) {
if (length < 0 || length > BigInt::kMaxLength) {
v8::internal::Heap::FatalProcessOutOfMemory("invalid BigInt length", true);
}
int size = BigInt::SizeFor(length);
AllocationSpace space = SelectSpace(pretenure);
HeapObject* result = nullptr;
{
AllocationResult allocation = AllocateRaw(size, space);
if (!allocation.To(&result)) return allocation;
}
result->set_map_after_allocation(bigint_map(), SKIP_WRITE_BARRIER);
BigInt::cast(result)->Initialize(length, zero_initialize);
return result;
}
AllocationResult Heap::AllocateCell(Object* value) {
int size = Cell::kSize;
STATIC_ASSERT(Cell::kSize <= kMaxRegularHeapObjectSize);
HeapObject* result = nullptr;
{
AllocationResult allocation = AllocateRaw(size, OLD_SPACE);
if (!allocation.To(&result)) return allocation;
}
result->set_map_after_allocation(cell_map(), SKIP_WRITE_BARRIER);
Cell::cast(result)->set_value(value);
return result;
}
AllocationResult Heap::AllocatePropertyCell(Name* name) {
DCHECK(name->IsUniqueName());
int size = PropertyCell::kSize;
STATIC_ASSERT(PropertyCell::kSize <= kMaxRegularHeapObjectSize);
HeapObject* result = nullptr;
AllocationResult allocation = AllocateRaw(size, OLD_SPACE);
if (!allocation.To(&result)) return allocation;
result->set_map_after_allocation(global_property_cell_map(),
SKIP_WRITE_BARRIER);
PropertyCell* cell = PropertyCell::cast(result);
cell->set_dependent_code(DependentCode::cast(empty_fixed_array()),
SKIP_WRITE_BARRIER);
cell->set_property_details(PropertyDetails(Smi::kZero));
cell->set_name(name);
cell->set_value(the_hole_value());
return result;
}
AllocationResult Heap::AllocateWeakCell(HeapObject* value) {
int size = WeakCell::kSize;
STATIC_ASSERT(WeakCell::kSize <= kMaxRegularHeapObjectSize);
HeapObject* result = nullptr;
{
AllocationResult allocation = AllocateRaw(size, OLD_SPACE);
if (!allocation.To(&result)) return allocation;
}
result->set_map_after_allocation(weak_cell_map(), SKIP_WRITE_BARRIER);
WeakCell::cast(result)->initialize(value);
return result;
}
AllocationResult Heap::AllocateTransitionArray(int capacity) {
DCHECK_LT(0, capacity);
HeapObject* raw_array = nullptr;
{
AllocationResult allocation = AllocateRawFixedArray(capacity, TENURED);
if (!allocation.To(&raw_array)) return allocation;
}
raw_array->set_map_after_allocation(transition_array_map(),
SKIP_WRITE_BARRIER);
TransitionArray* array = TransitionArray::cast(raw_array);
array->set_length(capacity);
MemsetPointer(array->data_start(), undefined_value(), capacity);
// Transition arrays are tenured. When black allocation is on we have to
// add the transition array to the list of encountered_transition_arrays.
if (incremental_marking()->black_allocation()) {
mark_compact_collector()->AddTransitionArray(array);
}
return array;
}
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::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());
// MacroAssembler::Abort calls (usually enabled with --debug-code) depend on
// CEntryStub, so we need to call GenerateStubsAheadOfTime before JSEntryStub
// is created.
// 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();
}
bool Heap::RootCanBeWrittenAfterInitialization(Heap::RootListIndex root_index) {
switch (root_index) {
case kNumberStringCacheRootIndex:
case kCodeStubsRootIndex:
case kScriptListRootIndex:
case kMaterializedObjectsRootIndex:
case kMicrotaskQueueRootIndex:
case kDetachedContextsRootIndex:
case kWeakObjectToCodeTableRootIndex:
case kWeakNewSpaceObjectToCodeListRootIndex:
case kRetainedMapsRootIndex:
case kRetainingPathTargetsRootIndex:
case kCodeCoverageListRootIndex:
case kNoScriptSharedFunctionInfosRootIndex:
case kWeakStackTraceListRootIndex:
case kSerializedTemplatesRootIndex:
case kSerializedGlobalProxySizesRootIndex:
case kPublicSymbolTableRootIndex:
case kApiSymbolTableRootIndex:
case kApiPrivateSymbolTableRootIndex:
case kMessageListenersRootIndex:
// Smi values
#define SMI_ENTRY(type, name, Name) case k##Name##RootIndex:
SMI_ROOT_LIST(SMI_ENTRY)
#undef SMI_ENTRY
// String table
case kStringTableRootIndex:
return true;
default:
return false;
}
}
bool Heap::RootCanBeTreatedAsConstant(RootListIndex 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;
}
int Heap::FullSizeNumberStringCacheLength() {
// Compute the size of the number string cache based on the max newspace size.
// The number string cache has a minimum size based on twice the initial cache
// size to ensure that it is bigger after being made 'full size'.
size_t number_string_cache_size = max_semi_space_size_ / 512;
number_string_cache_size =
Max(static_cast<size_t>(kInitialNumberStringCacheSize * 2),
Min<size_t>(0x4000u, number_string_cache_size));
// There is a string and a number per entry so the length is twice the number
// of entries.
return static_cast<int>(number_string_cache_size * 2);
}
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);
}
}
Map* Heap::MapForFixedTypedArray(ExternalArrayType array_type) {
return Map::cast(roots_[RootIndexForFixedTypedArray(array_type)]);
}
Heap::RootListIndex Heap::RootIndexForFixedTypedArray(
ExternalArrayType array_type) {
switch (array_type) {
#define ARRAY_TYPE_TO_ROOT_INDEX(Type, type, TYPE, ctype, size) \
case kExternal##Type##Array: \
return kFixed##Type##ArrayMapRootIndex;
TYPED_ARRAYS(ARRAY_TYPE_TO_ROOT_INDEX)
#undef ARRAY_TYPE_TO_ROOT_INDEX
default:
UNREACHABLE();
}
}
Heap::RootListIndex Heap::RootIndexForEmptyFixedTypedArray(
ElementsKind elementsKind) {
switch (elementsKind) {
#define ELEMENT_KIND_TO_ROOT_INDEX(Type, type, TYPE, ctype, size) \
case TYPE##_ELEMENTS: \
return kEmptyFixed##Type##ArrayRootIndex;
TYPED_ARRAYS(ELEMENT_KIND_TO_ROOT_INDEX)
#undef ELEMENT_KIND_TO_ROOT_INDEX
default:
UNREACHABLE();
}
}
FixedTypedArrayBase* Heap::EmptyFixedTypedArrayForMap(const Map* map) {
return FixedTypedArrayBase::cast(
roots_[RootIndexForEmptyFixedTypedArray(map->elements_kind())]);
}
AllocationResult Heap::AllocateForeign(Address address,
PretenureFlag pretenure) {
// Statically ensure that it is safe to allocate foreigns in paged spaces.
STATIC_ASSERT(Foreign::kSize <= kMaxRegularHeapObjectSize);
AllocationSpace space = (pretenure == TENURED) ? OLD_SPACE : NEW_SPACE;
Foreign* result = nullptr;
AllocationResult allocation = Allocate(foreign_map(), space);
if (!allocation.To(&result)) return allocation;
result->set_foreign_address(address);
return result;
}
AllocationResult Heap::AllocateSmallOrderedHashSet(int capacity,
PretenureFlag pretenure) {
DCHECK_EQ(0, capacity % SmallOrderedHashSet::kLoadFactor);
CHECK_GE(SmallOrderedHashSet::kMaxCapacity, capacity);
int size = SmallOrderedHashSet::Size(capacity);
AllocationSpace space = SelectSpace(pretenure);
HeapObject* result = nullptr;
{
AllocationResult allocation = AllocateRaw(size, space);
if (!allocation.To(&result)) return allocation;
}
result->set_map_after_allocation(small_ordered_hash_set_map(),
SKIP_WRITE_BARRIER);
Handle<SmallOrderedHashSet> table(SmallOrderedHashSet::cast(result));
table->Initialize(isolate(), capacity);
return result;
}
AllocationResult Heap::AllocateSmallOrderedHashMap(int capacity,
PretenureFlag pretenure) {
DCHECK_EQ(0, capacity % SmallOrderedHashMap::kLoadFactor);
CHECK_GE(SmallOrderedHashMap::kMaxCapacity, capacity);
int size = SmallOrderedHashMap::Size(capacity);
AllocationSpace space = SelectSpace(pretenure);
HeapObject* result = nullptr;
{
AllocationResult allocation = AllocateRaw(size, space);
if (!allocation.To(&result)) return allocation;
}
result->set_map_after_allocation(small_ordered_hash_map_map(),
SKIP_WRITE_BARRIER);
Handle<SmallOrderedHashMap> table(SmallOrderedHashMap::cast(result));
table->Initialize(isolate(), capacity);
return result;
}
AllocationResult Heap::AllocateByteArray(int length, PretenureFlag pretenure) {
if (length < 0 || length > ByteArray::kMaxLength) {
v8::internal::Heap::FatalProcessOutOfMemory("invalid array length", true);
}
int size = ByteArray::SizeFor(length);
AllocationSpace space = SelectSpace(pretenure);
HeapObject* result = nullptr;
{
AllocationResult allocation = AllocateRaw(size, space);
if (!allocation.To(&result)) return allocation;
}
result->set_map_after_allocation(byte_array_map(), SKIP_WRITE_BARRIER);
ByteArray::cast(result)->set_length(length);
ByteArray::cast(result)->clear_padding();
return result;
}
AllocationResult Heap::AllocateBytecodeArray(int length,
const byte* const raw_bytecodes,
int frame_size,
int parameter_count,
FixedArray* constant_pool) {
if (length < 0 || length > BytecodeArray::kMaxLength) {
v8::internal::Heap::FatalProcessOutOfMemory("invalid array length", true);
}
// Bytecode array is pretenured, so constant pool array should be to.
DCHECK(!InNewSpace(constant_pool));
int size = BytecodeArray::SizeFor(length);
HeapObject* result = nullptr;
{
AllocationResult allocation = AllocateRaw(size, OLD_SPACE);
if (!allocation.To(&result)) return allocation;
}
result->set_map_after_allocation(bytecode_array_map(), SKIP_WRITE_BARRIER);
BytecodeArray* instance = BytecodeArray::cast(result);
instance->set_length(length);
instance->set_frame_size(frame_size);
instance->set_parameter_count(parameter_count);
instance->set_incoming_new_target_or_generator_register(
interpreter::Register::invalid_value());
instance->set_interrupt_budget(interpreter::Interpreter::kInterruptBudget);
instance->set_osr_loop_nesting_level(0);
instance->set_bytecode_age(BytecodeArray::kNoAgeBytecodeAge);
instance->set_constant_pool(constant_pool);
instance->set_handler_table(empty_fixed_array());
instance->set_source_position_table(empty_byte_array());
CopyBytes(instance->GetFirstBytecodeAddress(), raw_bytecodes, length);
instance->clear_padding();
return result;
}
HeapObject* Heap::CreateFillerObjectAt(Address addr, int size,
ClearRecordedSlots mode) {
if (size == 0) return nullptr;
HeapObject* filler = HeapObject::FromAddress(addr);
if (size == kPointerSize) {
filler->set_map_after_allocation(
reinterpret_cast<Map*>(root(kOnePointerFillerMapRootIndex)),
SKIP_WRITE_BARRIER);
} else if (size == 2 * kPointerSize) {
filler->set_map_after_allocation(
reinterpret_cast<Map*>(root(kTwoPointerFillerMapRootIndex)),
SKIP_WRITE_BARRIER);
} else {
DCHECK_GT(size, 2 * kPointerSize);
filler->set_map_after_allocation(
reinterpret_cast<Map*>(root(kFreeSpaceMapRootIndex)),
SKIP_WRITE_BARRIER);
FreeSpace::cast(filler)->relaxed_write_size(size);
}
if (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 NULL.
DCHECK((filler->map() == NULL && !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;
}
FixedArrayBase* Heap::LeftTrimFixedArray(FixedArrayBase* object,
int elements_to_trim) {
CHECK_NOT_NULL(object);
DCHECK(CanMoveObjectStart(object));
DCHECK(!object->IsFixedTypedArrayBase());
DCHECK(!object->IsByteArray());
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() != 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.
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));
// Notify the heap profiler of change in object layout.
OnMoveEvent(new_object, object, new_object->Size());
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;
if (object->IsFixedTypedArrayBase()) {
InstanceType type = object->map()->instance_type();
bytes_to_trim =
FixedTypedArrayBase::TypedArraySize(type, len) -
FixedTypedArrayBase::TypedArraySize(type, len - elements_to_trim);
} else 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() || object->IsTransitionArray()) {
bytes_to_trim = elements_to_trim * kPointerSize;
} else {
DCHECK(object->IsFixedDoubleArray());
bytes_to_trim = elements_to_trim * kDoubleSize;
}
// For now this trick is only applied to objects in new and paged space.
DCHECK(object->map() != fixed_cow_array_map());
if (bytes_to_trim == 0) {
// No need to create filler and update live bytes counters, just initialize
// header of the trimmed array.
object->synchronized_set_length(len - elements_to_trim);
return;
}
// Calculate location of new array end.
Address old_end = object->address() + object->Size();
Address new_end = old_end - bytes_to_trim;
// 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(len - elements_to_trim);
// Notify the heap profiler of change in object layout. The array may not be
// moved during GC, and size has to be adjusted nevertheless.
HeapProfiler* profiler = isolate()->heap_profiler();
if (profiler->is_tracking_allocations()) {
profiler->UpdateObjectSizeEvent(object->address(), object->Size());
}
}
AllocationResult Heap::AllocateFixedTypedArrayWithExternalPointer(
int length, ExternalArrayType array_type, void* external_pointer,
PretenureFlag pretenure) {
int size = FixedTypedArrayBase::kHeaderSize;
AllocationSpace space = SelectSpace(pretenure);
HeapObject* result = nullptr;
{
AllocationResult allocation = AllocateRaw(size, space);
if (!allocation.To(&result)) return allocation;
}
result->set_map_after_allocation(MapForFixedTypedArray(array_type),
SKIP_WRITE_BARRIER);
FixedTypedArrayBase* elements = FixedTypedArrayBase::cast(result);
elements->set_base_pointer(Smi::kZero, SKIP_WRITE_BARRIER);
elements->set_external_pointer(external_pointer, SKIP_WRITE_BARRIER);
elements->set_length(length);
return elements;
}
static void ForFixedTypedArray(ExternalArrayType array_type, int* element_size,
ElementsKind* element_kind) {
switch (array_type) {
#define TYPED_ARRAY_CASE(Type, type, TYPE, ctype, size) \
case kExternal##Type##Array: \
*element_size = size; \
*element_kind = TYPE##_ELEMENTS; \
return;
TYPED_ARRAYS(TYPED_ARRAY_CASE)
#undef TYPED_ARRAY_CASE
default:
*element_size = 0; // Bogus
*element_kind = UINT8_ELEMENTS; // Bogus
UNREACHABLE();
}
}
AllocationResult Heap::AllocateFixedTypedArray(int length,
ExternalArrayType array_type,
bool initialize,
PretenureFlag pretenure) {
int element_size;
ElementsKind elements_kind;
ForFixedTypedArray(array_type, &element_size, &elements_kind);
int size = OBJECT_POINTER_ALIGN(length * element_size +
FixedTypedArrayBase::kDataOffset);
AllocationSpace space = SelectSpace(pretenure);
HeapObject* object = nullptr;
AllocationResult allocation = AllocateRaw(
size, space,
array_type == kExternalFloat64Array ? kDoubleAligned : kWordAligned);
if (!allocation.To(&object)) return allocation;
object->set_map_after_allocation(MapForFixedTypedArray(array_type),
SKIP_WRITE_BARRIER);
FixedTypedArrayBase* elements = FixedTypedArrayBase::cast(object);
elements->set_base_pointer(elements, SKIP_WRITE_BARRIER);
elements->set_external_pointer(
ExternalReference::fixed_typed_array_base_data_offset().address(),
SKIP_WRITE_BARRIER);
elements->set_length(length);
if (initialize) memset(elements->DataPtr(), 0, elements->DataSize());
return elements;
}
AllocationResult Heap::AllocateCode(int object_size, bool immovable) {
DCHECK(IsAligned(static_cast<intptr_t>(object_size), kCodeAlignment));
AllocationResult allocation = AllocateRaw(object_size, CODE_SPACE);
HeapObject* result = nullptr;
if (!allocation.To(&result)) return allocation;
if (immovable) {
Address address = result->address();
MemoryChunk* chunk = MemoryChunk::FromAddress(address);
// Code objects which should stay at a fixed address are allocated either
// in the first page of code space (objects on the first page of each space
// are never moved), in large object space, or (during snapshot creation)
// the containing page is marked as immovable.
if (!Heap::IsImmovable(result) &&
!code_space_->FirstPage()->Contains(address)) {
if (isolate()->serializer_enabled()) {
chunk->MarkNeverEvacuate();
} else {
// Discard the first code allocation, which was on a page where it could
// be moved.
CreateFillerObjectAt(result->address(), object_size,
ClearRecordedSlots::kNo);
allocation = lo_space_->AllocateRaw(object_size, EXECUTABLE);
if (!allocation.To(&result)) return allocation;
OnAllocationEvent(result, object_size);
}
}
}
result->set_map_after_allocation(code_map(), SKIP_WRITE_BARRIER);
Code* code = Code::cast(result);
DCHECK(IsAligned(bit_cast<intptr_t>(code->address()), kCodeAlignment));
DCHECK(!memory_allocator()->code_range()->valid() ||
memory_allocator()->code_range()->contains(code->address()) ||
object_size <= code_space()->AreaSize());
return code;
}
AllocationResult Heap::CopyCode(Code* code) {
AllocationResult allocation;
HeapObject* result = nullptr;
// Allocate an object the same size as the code object.
int obj_size = code->Size();
allocation = AllocateRaw(obj_size, CODE_SPACE);
if (!allocation.To(&result)) return allocation;
// Copy code object.
Address old_addr = code->address();
Address new_addr = result->address();
CopyBlock(new_addr, old_addr, obj_size);
Code* new_code = Code::cast(result);
// Relocate the copy.
DCHECK(IsAligned(bit_cast<intptr_t>(new_code->address()), kCodeAlignment));
DCHECK(!memory_allocator()->code_range()->valid() ||
memory_allocator()->code_range()->contains(code->address()) ||
obj_size <= code_space()->AreaSize());
// Clear the trap handler index since they can't be shared between code. We
// have to do this before calling Relocate becauase relocate would adjust the
// base pointer for the old code.
new_code->set_trap_handler_index(Smi::FromInt(trap_handler::kInvalidIndex));
new_code->Relocate(new_addr - old_addr);
// We have to iterate over the object and process its pointers when black
// allocation is on.
incremental_marking()->ProcessBlackAllocatedObject(new_code);
// Record all references to embedded objects in the new code object.
RecordWritesIntoCode(new_code);
return new_code;
}
AllocationResult Heap::CopyBytecodeArray(BytecodeArray* bytecode_array) {
int size = BytecodeArray::SizeFor(bytecode_array->length());
HeapObject* result = nullptr;
{
AllocationResult allocation = AllocateRaw(size, OLD_SPACE);
if (!allocation.To(&result)) return allocation;
}
result->set_map_after_allocation(bytecode_array_map(), SKIP_WRITE_BARRIER);
BytecodeArray* copy = BytecodeArray::cast(result);
copy->set_length(bytecode_array->length());
copy->set_frame_size(bytecode_array->frame_size());
copy->set_parameter_count(bytecode_array->parameter_count());
copy->set_incoming_new_target_or_generator_register(
bytecode_array->incoming_new_target_or_generator_register());
copy->set_constant_pool(bytecode_array->constant_pool());
copy->set_handler_table(bytecode_array->handler_table());
copy->set_source_position_table(bytecode_array->source_position_table());
copy->set_interrupt_budget(bytecode_array->interrupt_budget());
copy->set_osr_loop_nesting_level(bytecode_array->osr_loop_nesting_level());
copy->set_bytecode_age(bytecode_array->bytecode_age());
bytecode_array->CopyBytecodesTo(copy);
return copy;
}
void Heap::InitializeAllocationMemento(AllocationMemento* memento,
AllocationSite* allocation_site) {
memento->set_map_after_allocation(allocation_memento_map(),
SKIP_WRITE_BARRIER);
DCHECK(allocation_site->map() == allocation_site_map());
memento->set_allocation_site(allocation_site, SKIP_WRITE_BARRIER);
if (FLAG_allocation_site_pretenuring) {
allocation_site->IncrementMementoCreateCount();
}
}
AllocationResult Heap::Allocate(Map* map, AllocationSpace space,
AllocationSite* allocation_site) {
DCHECK(gc_state_ == NOT_IN_GC);
DCHECK(map->instance_type() != MAP_TYPE);
int size = map->instance_size();
if (allocation_site != NULL) {
size += AllocationMemento::kSize;
}
HeapObject* result = nullptr;
AllocationResult allocation = AllocateRaw(size, space);
if (!allocation.To(&result)) return allocation;
// New space objects are allocated white.
WriteBarrierMode write_barrier_mode =
space == NEW_SPACE ? SKIP_WRITE_BARRIER : UPDATE_WRITE_BARRIER;
result->set_map_after_allocation(map, write_barrier_mode);
if (allocation_site != NULL) {
AllocationMemento* alloc_memento = reinterpret_cast<AllocationMemento*>(
reinterpret_cast<Address>(result) + map->instance_size());
InitializeAllocationMemento(alloc_memento, allocation_site);
}
return result;
}
void Heap::InitializeJSObjectFromMap(JSObject* obj, Object* properties,
Map* map) {
obj->set_raw_properties_or_hash(properties);
obj->initialize_elements();
// TODO(1240798): Initialize the object's body using valid initial values
// according to the object's initial map. For example, if the map's
// instance type is JS_ARRAY_TYPE, the length field should be initialized
// to a number (e.g. Smi::kZero) and the elements initialized to a
// fixed array (e.g. Heap::empty_fixed_array()). Currently, the object
// verification code has to cope with (temporarily) invalid objects. See
// for example, JSArray::JSArrayVerify).
InitializeJSObjectBody(obj, map, JSObject::kHeaderSize);
}
void Heap::InitializeJSObjectBody(JSObject* obj, Map* map, int start_offset) {
if (start_offset == map->instance_size()) return;
DCHECK_LT(start_offset, map->instance_size());
// We cannot always fill with one_pointer_filler_map because objects
// created from API functions expect their embedder fields to be initialized
// with undefined_value.
// Pre-allocated fields need to be initialized with undefined_value as well
// so that object accesses before the constructor completes (e.g. in the
// debugger) will not cause a crash.
// In case of Array subclassing the |map| could already be transitioned
// to different elements kind from the initial map on which we track slack.
bool in_progress = map->IsInobjectSlackTrackingInProgress();
Object* filler;
if (in_progress) {
filler = one_pointer_filler_map();
} else {
filler = undefined_value();
}
obj->InitializeBody(map, start_offset, Heap::undefined_value(), filler);
if (in_progress) {
map->FindRootMap()->InobjectSlackTrackingStep();
}
}
AllocationResult Heap::AllocateJSObjectFromMap(
Map* map, PretenureFlag pretenure, AllocationSite* allocation_site) {
// JSFunctions should be allocated using AllocateFunction to be
// properly initialized.
DCHECK(map->instance_type() != JS_FUNCTION_TYPE);
// Both types of global objects should be allocated using
// AllocateGlobalObject to be properly initialized.
DCHECK(map->instance_type() != JS_GLOBAL_OBJECT_TYPE);
// Allocate the backing storage for the properties.
FixedArray* properties = empty_fixed_array();
// Allocate the JSObject.
AllocationSpace space = SelectSpace(pretenure);
JSObject* js_obj = nullptr;
AllocationResult allocation = Allocate(map, space, allocation_site);
if (!allocation.To(&js_obj)) return allocation;
// Initialize the JSObject.
InitializeJSObjectFromMap(js_obj, properties, map);
DCHECK(js_obj->HasFastElements() || js_obj->HasFixedTypedArrayElements() ||
js_obj->HasFastStringWrapperElements() ||
js_obj->HasFastArgumentsElements());
return js_obj;
}
AllocationResult Heap::AllocateJSObject(JSFunction* constructor,
PretenureFlag pretenure,
AllocationSite* allocation_site) {
DCHECK(constructor->has_initial_map());
// Allocate the object based on the constructors initial map.
AllocationResult allocation = AllocateJSObjectFromMap(
constructor->initial_map(), pretenure, allocation_site);
#ifdef DEBUG
// Make sure result is NOT a global object if valid.
HeapObject* obj = nullptr;
DCHECK(!allocation.To(&obj) || !obj->IsJSGlobalObject());
#endif
return allocation;
}
AllocationResult Heap::CopyJSObject(JSObject* source, AllocationSite* site) {
// Make the clone.
Map* map = source->map();
// We can only clone regexps, normal objects, api objects, errors or arrays.
// Copying anything else will break invariants.
CHECK(map->instance_type() == JS_REGEXP_TYPE ||
map->instance_type() == JS_OBJECT_TYPE ||
map->instance_type() == JS_ERROR_TYPE ||
map->instance_type() == JS_ARRAY_TYPE ||
map->instance_type() == JS_API_OBJECT_TYPE ||
map->instance_type() == WASM_INSTANCE_TYPE ||
map->instance_type() == WASM_MEMORY_TYPE ||
map->instance_type() == WASM_MODULE_TYPE ||
map->instance_type() == WASM_TABLE_TYPE ||
map->instance_type() == JS_SPECIAL_API_OBJECT_TYPE);
int object_size = map->instance_size();
HeapObject* clone = nullptr;
DCHECK(site == NULL || AllocationSite::CanTrack(map->instance_type()));
int adjusted_object_size =
site != NULL ? object_size + AllocationMemento::kSize : object_size;
AllocationResult allocation = AllocateRaw(adjusted_object_size, NEW_SPACE);
if (!allocation.To(&clone)) return allocation;
SLOW_DCHECK(InNewSpace(clone));
// Since we know the clone is allocated in new space, we can copy
// the contents without worrying about updating the write barrier.
CopyBlock(clone->address(), source->address(), object_size);
if (site != NULL) {
AllocationMemento* alloc_memento = reinterpret_cast<AllocationMemento*>(
reinterpret_cast<Address>(clone) + object_size);
InitializeAllocationMemento(alloc_memento, site);
}
SLOW_DCHECK(JSObject::cast(clone)->GetElementsKind() ==
source->GetElementsKind());
FixedArrayBase* elements = FixedArrayBase::cast(source->elements());
// Update elements if necessary.
if (elements->length() > 0) {
FixedArrayBase* elem = nullptr;
{
AllocationResult allocation;
if (elements->map() == fixed_cow_array_map()) {
allocation = FixedArray::cast(elements);
} else if (source->HasDoubleElements()) {
allocation = CopyFixedDoubleArray(FixedDoubleArray::cast(elements));
} else {
allocation = CopyFixedArray(FixedArray::cast(elements));
}
if (!allocation.To(&elem)) return allocation;
}
JSObject::cast(clone)->set_elements(elem, SKIP_WRITE_BARRIER);
}
// Update properties if necessary.
if (source->HasFastProperties()) {
if (source->property_array()->length() > 0) {
PropertyArray* properties = source->property_array();
PropertyArray* prop = nullptr;
{
// TODO(gsathya): Do not copy hash code.
AllocationResult allocation = CopyPropertyArray(properties);
if (!allocation.To(&prop)) return allocation;
}
JSObject::cast(clone)->set_raw_properties_or_hash(prop,
SKIP_WRITE_BARRIER);
}
} else {
FixedArray* properties = FixedArray::cast(source->property_dictionary());
FixedArray* prop = nullptr;
{
AllocationResult allocation = CopyFixedArray(properties);
if (!allocation.To(&prop)) return allocation;
}
JSObject::cast(clone)->set_raw_properties_or_hash(prop, SKIP_WRITE_BARRIER);
}
// Return the new clone.
return clone;
}
static inline void WriteOneByteData(Vector<const char> vector, uint8_t* chars,
int len) {
// Only works for one byte strings.
DCHECK(vector.length() == len);
MemCopy(chars, vector.start(), len);
}
static inline void WriteTwoByteData(Vector<const char> vector, uint16_t* chars,
int len) {
const uint8_t* stream = reinterpret_cast<const uint8_t*>(vector.start());
size_t stream_length = vector.length();
while (stream_length != 0) {
size_t consumed = 0;
uint32_t c = unibrow::Utf8::ValueOf(stream, stream_length, &consumed);
DCHECK_NE(unibrow::Utf8::kBadChar, c);
DCHECK(consumed <= stream_length);
stream_length -= consumed;
stream += consumed;
if (c > unibrow::Utf16::kMaxNonSurrogateCharCode) {
len -= 2;
if (len < 0) break;
*chars++ = unibrow::Utf16::LeadSurrogate(c);
*chars++ = unibrow::Utf16::TrailSurrogate(c);
} else {
len -= 1;
if (len < 0) break;
*chars++ = c;
}
}
DCHECK_EQ(0, stream_length);
DCHECK_EQ(0, len);
}
static inline void WriteOneByteData(String* s, uint8_t* chars, int len) {
DCHECK(s->length() == len);
String::WriteToFlat(s, chars, 0, len);
}
static inline void WriteTwoByteData(String* s, uint16_t* chars, int len) {
DCHECK(s->length() == len);
String::WriteToFlat(s, chars, 0, len);
}
template <bool is_one_byte, typename T>
AllocationResult Heap::AllocateInternalizedStringImpl(T t, int chars,
uint32_t hash_field) {
DCHECK_LE(0, chars);
// Compute map and object size.
int size;
Map* map;
DCHECK_LE(0, chars);
DCHECK_GE(String::kMaxLength, chars);
if (is_one_byte) {
map = one_byte_internalized_string_map();
size = SeqOneByteString::SizeFor(chars);
} else {
map = internalized_string_map();
size = SeqTwoByteString::SizeFor(chars);
}
// Allocate string.
HeapObject* result = nullptr;
{
AllocationResult allocation = AllocateRaw(size, OLD_SPACE);
if (!allocation.To(&result)) return allocation;
}
result->set_map_after_allocation(map, SKIP_WRITE_BARRIER);
// Set length and hash fields of the allocated string.
String* answer = String::cast(result);
answer->set_length(chars);
answer->set_hash_field(hash_field);
DCHECK_EQ(size, answer->Size());
if (is_one_byte) {
WriteOneByteData(t, SeqOneByteString::cast(answer)->GetChars(), chars);
} else {
WriteTwoByteData(t, SeqTwoByteString::cast(answer)->GetChars(), chars);
}
return answer;
}
// Need explicit instantiations.
template AllocationResult Heap::AllocateInternalizedStringImpl<true>(String*,
int,
uint32_t);
template AllocationResult Heap::AllocateInternalizedStringImpl<false>(String*,
int,
uint32_t);
template AllocationResult Heap::AllocateInternalizedStringImpl<false>(
Vector<const char>, int, uint32_t);
AllocationResult Heap::AllocateRawOneByteString(int length,
PretenureFlag pretenure) {
DCHECK_LE(0, length);
DCHECK_GE(String::kMaxLength, length);
int size = SeqOneByteString::SizeFor(length);
DCHECK_GE(SeqOneByteString::kMaxSize, size);
AllocationSpace space = SelectSpace(pretenure);
HeapObject* result = nullptr;
{
AllocationResult allocation = AllocateRaw(size, space);
if (!allocation.To(&result)) return allocation;
}
// Partially initialize the object.
result->set_map_after_allocation(one_byte_string_map(), SKIP_WRITE_BARRIER);
String::cast(result)->set_length(length);
String::cast(result)->set_hash_field(String::kEmptyHashField);
DCHECK_EQ(size, HeapObject::cast(result)->Size());
return result;
}
AllocationResult Heap::AllocateRawTwoByteString(int length,
PretenureFlag pretenure) {
DCHECK_LE(0, length);
DCHECK_GE(String::kMaxLength, length);
int size = SeqTwoByteString::SizeFor(length);
DCHECK_GE(SeqTwoByteString::kMaxSize, size);
AllocationSpace space = SelectSpace(pretenure);
HeapObject* result = nullptr;
{
AllocationResult allocation = AllocateRaw(size, space);
if (!allocation.To(&result)) return allocation;
}
// Partially initialize the object.
result->set_map_after_allocation(string_map(), SKIP_WRITE_BARRIER);
String::cast(result)->set_length(length);
String::cast(result)->set_hash_field(String::kEmptyHashField);
DCHECK_EQ(size, HeapObject::cast(result)->Size());
return result;
}
AllocationResult Heap::AllocateEmptyFixedArray() {
int size = FixedArray::SizeFor(0);
HeapObject* result = nullptr;
{
AllocationResult allocation = AllocateRaw(size, OLD_SPACE);
if (!allocation.To(&result)) return allocation;
}
// Initialize the object.
result->set_map_after_allocation(fixed_array_map(), SKIP_WRITE_BARRIER);
FixedArray::cast(result)->set_length(0);
return result;
}
AllocationResult Heap::AllocateEmptyScopeInfo() {
int size = FixedArray::SizeFor(0);
HeapObject* result = nullptr;
{
AllocationResult allocation = AllocateRaw(size, OLD_SPACE);
if (!allocation.To(&result)) return allocation;
}
// Initialize the object.
result->set_map_after_allocation(scope_info_map(), SKIP_WRITE_BARRIER);
FixedArray::cast(result)->set_length(0);
return result;
}
AllocationResult Heap::CopyAndTenureFixedCOWArray(FixedArray* src) {
if (!InNewSpace(src)) {
return src;
}
int len = src->length();
HeapObject* obj = nullptr;
{
AllocationResult allocation = AllocateRawFixedArray(len, TENURED);
if (!allocation.To(&obj)) return allocation;
}
obj->set_map_after_allocation(fixed_array_map(), SKIP_WRITE_BARRIER);
FixedArray* result = FixedArray::cast(obj);
result->set_length(len);
// Copy the content.
DisallowHeapAllocation no_gc;
WriteBarrierMode mode = result->GetWriteBarrierMode(no_gc);
for (int i = 0; i < len; i++) result->set(i, src->get(i), mode);
// TODO(mvstanton): The map is set twice because of protection against calling
// set() on a COW FixedArray. Issue v8:3221 created to track this, and
// we might then be able to remove this whole method.
HeapObject::cast(obj)->set_map_after_allocation(fixed_cow_array_map(),
SKIP_WRITE_BARRIER);
return result;
}
AllocationResult Heap::AllocateEmptyFixedTypedArray(
ExternalArrayType array_type) {
return AllocateFixedTypedArray(0, array_type, false, TENURED);
}
namespace {
template <typename T>
void initialize_length(T* array, int length) {
array->set_length(length);
}
template <>
void initialize_length<PropertyArray>(PropertyArray* array, int length) {
array->initialize_length(length);
}
} // namespace
template <typename T>
AllocationResult Heap::CopyArrayAndGrow(T* src, int grow_by,
PretenureFlag pretenure) {
int old_len = src->length();
int new_len = old_len + grow_by;
DCHECK(new_len >= old_len);
HeapObject* obj = nullptr;
{
AllocationResult allocation = AllocateRawFixedArray(new_len, pretenure);
if (!allocation.To(&obj)) return allocation;
}
obj->set_map_after_allocation(src->map(), SKIP_WRITE_BARRIER);
T* result = T::cast(obj);
initialize_length(result, new_len);
// Copy the content.
DisallowHeapAllocation no_gc;
WriteBarrierMode mode = obj->GetWriteBarrierMode(no_gc);
for (int i = 0; i < old_len; i++) result->set(i, src->get(i), mode);
MemsetPointer(result->data_start() + old_len, undefined_value(), grow_by);
return result;
}
template AllocationResult Heap::CopyArrayAndGrow(FixedArray* src, int grow_by,
PretenureFlag pretenure);
template AllocationResult Heap::CopyArrayAndGrow(PropertyArray* src,
int grow_by,
PretenureFlag pretenure);
AllocationResult Heap::CopyFixedArrayUpTo(FixedArray* src, int new_len,
PretenureFlag pretenure) {
if (new_len == 0) return empty_fixed_array();
DCHECK_LE(new_len, src->length());
HeapObject* obj = nullptr;
{
AllocationResult allocation = AllocateRawFixedArray(new_len, pretenure);
if (!allocation.To(&obj)) return allocation;
}
obj->set_map_after_allocation(fixed_array_map(), SKIP_WRITE_BARRIER);
FixedArray* result = FixedArray::cast(obj);
result->set_length(new_len);
// Copy the content.
DisallowHeapAllocation no_gc;
WriteBarrierMode mode = result->GetWriteBarrierMode(no_gc);
for (int i = 0; i < new_len; i++) result->set(i, src->get(i), mode);
return result;
}
template <typename T>
AllocationResult Heap::CopyArrayWithMap(T* src, Map* map) {
int len = src->length();
HeapObject* obj = nullptr;
{
AllocationResult allocation = AllocateRawFixedArray(len, NOT_TENURED);
if (!allocation.To(&obj)) return allocation;
}
obj->set_map_after_allocation(map, SKIP_WRITE_BARRIER);
T* result = T::cast(obj);
DisallowHeapAllocation no_gc;
WriteBarrierMode mode = result->GetWriteBarrierMode(no_gc);
// Eliminate the write barrier if possible.
if (mode == SKIP_WRITE_BARRIER) {
CopyBlock(obj->address() + kPointerSize, src->address() + kPointerSize,
T::SizeFor(len) - kPointerSize);
return obj;
}
// Slow case: Just copy the content one-by-one.
initialize_length(result, len);
for (int i = 0; i < len; i++) result->set(i, src->get(i), mode);
return result;
}
template AllocationResult Heap::CopyArrayWithMap(FixedArray* src, Map* map);
template AllocationResult Heap::CopyArrayWithMap(PropertyArray* src, Map* map);
AllocationResult Heap::CopyFixedArrayWithMap(FixedArray* src, Map* map) {
return CopyArrayWithMap(src, map);
}
AllocationResult Heap::CopyPropertyArray(PropertyArray* src) {
return CopyArrayWithMap(src, property_array_map());
}
AllocationResult Heap::CopyFixedDoubleArrayWithMap(FixedDoubleArray* src,
Map* map) {
int len = src->length();
HeapObject* obj = nullptr;
{
AllocationResult allocation = AllocateRawFixedDoubleArray(len, NOT_TENURED);
if (!allocation.To(&obj)) return allocation;
}
obj->set_map_after_allocation(map, SKIP_WRITE_BARRIER);
CopyBlock(obj->address() + FixedDoubleArray::kLengthOffset,
src->address() + FixedDoubleArray::kLengthOffset,
FixedDoubleArray::SizeFor(len) - FixedDoubleArray::kLengthOffset);
return obj;
}
AllocationResult Heap::CopyFeedbackVector(FeedbackVector* src) {
int len = src->length();
HeapObject* obj = nullptr;
{
AllocationResult allocation = AllocateRawFeedbackVector(len, NOT_TENURED);
if (!allocation.To(&obj)) return allocation;
}
obj->set_map_after_allocation(feedback_vector_map(), SKIP_WRITE_BARRIER);
FeedbackVector* result = FeedbackVector::cast(obj);
DisallowHeapAllocation no_gc;
WriteBarrierMode mode = result->GetWriteBarrierMode(no_gc);
// Eliminate the write barrier if possible.
if (mode == SKIP_WRITE_BARRIER) {
CopyBlock(result->address() + kPointerSize,
result->address() + kPointerSize,
FeedbackVector::SizeFor(len) - kPointerSize);
return result;
}
// Slow case: Just copy the content one-by-one.
result->set_shared_function_info(src->shared_function_info());
result->set_optimized_code_cell(src->optimized_code_cell());
result->set_invocation_count(src->invocation_count());
result->set_profiler_ticks(src->profiler_ticks());
result->set_deopt_count(src->deopt_count());
for (int i = 0; i < len; i++) result->set(i, src->get(i), mode);
return result;
}
AllocationResult Heap::AllocateRawFixedArray(int length,
PretenureFlag pretenure) {
if (length < 0 || length > FixedArray::kMaxLength) {
v8::internal::Heap::FatalProcessOutOfMemory("invalid array length", true);
}
int size = FixedArray::SizeFor(length);
AllocationSpace space = SelectSpace(pretenure);
AllocationResult result = AllocateRaw(size, space);
if (!result.IsRetry() && size > kMaxRegularHeapObjectSize &&
FLAG_use_marking_progress_bar) {
MemoryChunk* chunk =
MemoryChunk::FromAddress(result.ToObjectChecked()->address());
chunk->SetFlag<AccessMode::ATOMIC>(MemoryChunk::HAS_PROGRESS_BAR);
}
return result;
}
AllocationResult Heap::AllocateFixedArrayWithFiller(int length,
PretenureFlag pretenure,
Object* filler) {
DCHECK_LE(0, length);
DCHECK(empty_fixed_array()->IsFixedArray());
if (length == 0) return empty_fixed_array();
DCHECK(!InNewSpace(filler));
HeapObject* result = nullptr;
{
AllocationResult allocation = AllocateRawFixedArray(length, pretenure);
if (!allocation.To(&result)) return allocation;
}
result->set_map_after_allocation(fixed_array_map(), SKIP_WRITE_BARRIER);
FixedArray* array = FixedArray::cast(result);
array->set_length(length);
MemsetPointer(array->data_start(), filler, length);
return array;
}
AllocationResult Heap::AllocatePropertyArray(int length,
PretenureFlag pretenure) {
DCHECK_LE(0, length);
DCHECK(!InNewSpace(undefined_value()));
HeapObject* result = nullptr;
{
AllocationResult allocation = AllocateRawFixedArray(length, pretenure);
if (!allocation.To(&result)) return allocation;
}
result->set_map_after_allocation(property_array_map(), SKIP_WRITE_BARRIER);
PropertyArray* array = PropertyArray::cast(result);
array->initialize_length(length);
MemsetPointer(array->data_start(), undefined_value(), length);
return result;
}
AllocationResult Heap::AllocateUninitializedFixedArray(
int length, PretenureFlag pretenure) {
if (length == 0) return empty_fixed_array();
HeapObject* obj = nullptr;
{
AllocationResult allocation = AllocateRawFixedArray(length, pretenure);
if (!allocation.To(&obj)) return allocation;
}
obj->set_map_after_allocation(fixed_array_map(), SKIP_WRITE_BARRIER);
FixedArray::cast(obj)->set_length(length);
return obj;
}
AllocationResult Heap::AllocateUninitializedFixedDoubleArray(
int length, PretenureFlag pretenure) {
if (length == 0) return empty_fixed_array();
HeapObject* elements = nullptr;
AllocationResult allocation = AllocateRawFixedDoubleArray(length, pretenure);
if (!allocation.To(&elements)) return allocation;
elements->set_map_after_allocation(fixed_double_array_map(),
SKIP_WRITE_BARRIER);
FixedDoubleArray::cast(elements)->set_length(length);
return elements;
}
AllocationResult Heap::AllocateRawFixedDoubleArray(int length,
PretenureFlag pretenure) {
if (length < 0 || length > FixedDoubleArray::kMaxLength) {
v8::internal::Heap::FatalProcessOutOfMemory("invalid array length", true);
}
int size = FixedDoubleArray::SizeFor(length);
AllocationSpace space = SelectSpace(pretenure);
HeapObject* object = nullptr;
{
AllocationResult allocation = AllocateRaw(size, space, kDoubleAligned);
if (!allocation.To(&object)) return allocation;
}
return object;
}
AllocationResult Heap::AllocateRawFeedbackVector(int length,
PretenureFlag pretenure) {
DCHECK_LE(0, length);
int size = FeedbackVector::SizeFor(length);
AllocationSpace space = SelectSpace(pretenure);
HeapObject* object = nullptr;
{
AllocationResult allocation = AllocateRaw(size, space);
if (!allocation.To(&object)) return allocation;
}
return object;
}
AllocationResult Heap::AllocateFeedbackVector(SharedFunctionInfo* shared,
PretenureFlag pretenure) {
int length = shared->feedback_metadata()->slot_count();
HeapObject* result = nullptr;
{
AllocationResult allocation = AllocateRawFeedbackVector(length, pretenure);
if (!allocation.To(&result)) return allocation;
}
// Initialize the object's map.
result->set_map_after_allocation(feedback_vector_map(), SKIP_WRITE_BARRIER);
FeedbackVector* vector = FeedbackVector::cast(result);
vector->set_shared_function_info(shared);
vector->set_optimized_code_cell(Smi::FromEnum(OptimizationMarker::kNone));
vector->set_length(length);
vector->set_invocation_count(0);
vector->set_profiler_ticks(0);
vector->set_deopt_count(0);
// TODO(leszeks): Initialize based on the feedback metadata.
MemsetPointer(vector->slots_start(), undefined_value(), length);
return vector;
}
AllocationResult Heap::AllocateSymbol() {
// Statically ensure that it is safe to allocate symbols in paged spaces.
STATIC_ASSERT(Symbol::kSize <= kMaxRegularHeapObjectSize);
HeapObject* result = nullptr;
AllocationResult allocation = AllocateRaw(Symbol::kSize, OLD_SPACE);
if (!allocation.To(&result)) return allocation;
result->set_map_after_allocation(symbol_map(), SKIP_WRITE_BARRIER);
// Generate a random hash value.
int hash = isolate()->GenerateIdentityHash(Name::kHashBitMask);
Symbol::cast(result)
->set_hash_field(Name::kIsNotArrayIndexMask | (hash << Name::kHashShift));
Symbol::cast(result)->set_name(undefined_value());
Symbol::cast(result)->set_flags(0);
DCHECK(!Symbol::cast(result)->is_private());
return result;
}
AllocationResult Heap::AllocateStruct(InstanceType type,
PretenureFlag pretenure) {
Map* map;
switch (type) {
#define MAKE_CASE(NAME, Name, name) \
case NAME##_TYPE: \
map = name##_map(); \
break;
STRUCT_LIST(MAKE_CASE)
#undef MAKE_CASE
default:
UNREACHABLE();
}
int size = map->instance_size();
Struct* result = nullptr;
{
AllocationSpace space = SelectSpace(pretenure);
AllocationResult allocation = Allocate(map, space);
if (!allocation.To(&result)) return allocation;
}
result->InitializeBody(size);
return result;
}
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<double>(
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<double>(
tracer()->OldGenerationAllocationThroughputInBytesPerMillisecond());
double gc_speed = static_cast<double>(
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::HasHighFragmentation() {
size_t used = PromotedSpaceSizeOfObjects();
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() {
return FLAG_optimize_for_size || isolate()->IsIsolateInBackground() ||
HighMemoryPressure();
}
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()))) {
FinalizeIncrementalMarking(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::RegisterDeserializedObjectsForBlackAllocation(
Reservation* reservations, const std::vector<HeapObject*>& large_objects,
const std::vector<Address>& 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&) {
DCHECK(InOldSpace(object) || InNewSpace(object) ||
(lo_space()->Contains(object) && object->IsString()));
if (FLAG_incremental_marking && incremental_marking()->IsMarking()) {
incremental_marking()->MarkBlackAndPush(object);
if (InOldSpace(object) && incremental_marking()->IsCompacting()) {
// The concurrent marker might have recorded slots for the object.
// Register this object as invalidated to filter out the slots.
MemoryChunk* chunk = MemoryChunk::FromAddress(object->address());
chunk->RegisterObjectWithInvalidatedSlots(object, size);
}
}
#ifdef 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 {
for (Object** p = start; p < end; p++) {
slots_.push_back(p);
}
}
int number_of_slots() { return static_cast<int>(slots_.size()); }
Object** slot(int i) { return slots_[i]; }
private:
std::vector<Object**> slots_;
};
void Heap::VerifyObjectLayoutChange(HeapObject* object, Map* new_map) {
// 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<size_t>(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,
IncrementalMarking::FORCE_COMPLETION, 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 (deadline_in_ms - start_ms >
GCIdleTimeHandler::kMaxFrameRenderingIdleTime) {
int committed_memory = static_cast<int>(CommittedMemory() / KB);
int used_memory = static_cast<int>(heap_state.size_of_objects / KB);
isolate()->counters()->aggregated_memory_heap_committed()->AddSample(
start_ms, committed_memory);
isolate()->counters()->aggregated_memory_heap_used()->AddSample(
start_ms, used_memory);
}
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<double>(base::Time::kMillisecondsPerSecond);
}
bool Heap::IdleNotification(int idle_time_in_ms) {
return IdleNotification(
V8::GetCurrentPlatform()->MonotonicallyIncreasingTime() +
(static_cast<double>(idle_time_in_ms) /
static_cast<double>(base::Time::kMillisecondsPerSecond)));
}
bool Heap::IdleNotification(double deadline_in_seconds) {
CHECK(HasBeenSetUp());
double deadline_in_ms =
deadline_in_seconds *
static_cast<double>(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) {}
virtual ~MemoryPressureInterruptTask() {}
private:
// v8::internal::CancelableTask overrides.
void RunInternal() override { heap_->CheckMemoryPressure(); }
Heap* heap_;
DISALLOW_COPY_AND_ASSIGN(MemoryPressureInterruptTask);
};
void Heap::CheckMemoryPressure() {
if (HighMemoryPressure()) {
if (isolate()->concurrent_recompilation_enabled()) {
// The optimizing compiler may be unnecessarily holding on to memory.
DisallowHeapAllocation no_recursive_gc;
isolate()->optimizing_compile_dispatcher()->Flush(
OptimizingCompileDispatcher::BlockingBehavior::kDontBlock);
}
}
if (memory_pressure_level_.Value() == MemoryPressureLevel::kCritical) {
CollectGarbageOnMemoryPressure();
} else if (memory_pressure_level_.Value() == 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 | kAbortIncrementalMarkingMask,
GarbageCollectionReason::kMemoryPressure,
kGCCallbackFlagCollectAllAvailableGarbage);
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 | kAbortIncrementalMarkingMask,
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_.Value();
memory_pressure_level_.SetValue(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();
V8::GetCurrentPlatform()->CallOnForegroundThread(
reinterpret_cast<v8::Isolate*>(isolate()),
new MemoryPressureInterruptTask(this));
}
}
}
void Heap::SetOutOfMemoryCallback(v8::debug::OutOfMemoryCallback callback,
void* data) {
out_of_memory_callback_ = callback;
out_of_memory_callback_data_ = data;
}
void Heap::InvokeOutOfMemoryCallback() {
if (out_of_memory_callback_) {
out_of_memory_callback_(out_of_memory_callback_data_);
}
}
void 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);
AllSpaces spaces(this);
for (Space* space = spaces.next(); space != NULL; space = spaces.next()) {
space->Print();
}
}
void Heap::ReportCodeStatistics(const char* title) {
PrintF(">>>>>> Code Stats (%s) >>>>>>\n", title);
CollectCodeStatistics();
CodeStatistics::ReportCodeStatistics(isolate());
}
// This function expects that NewSpace's allocated objects histogram is
// populated (via a call to CollectStatistics or else as a side effect of a
// just-completed scavenge collection).
void Heap::ReportHeapStatistics(const char* title) {
USE(title);
PrintF(">>>>>> =============== %s (%d) =============== >>>>>>\n", title,
gc_count_);
PrintF("old_generation_allocation_limit_ %" PRIuS "\n",
old_generation_allocation_limit_);
PrintF("\n");
PrintF("Number of handles : %d\n", HandleScope::NumberOfHandles(isolate_));
isolate_->global_handles()->PrintStats();
PrintF("\n");
PrintF("Heap statistics : ");
memory_allocator()->ReportStatistics();
PrintF("To space : ");
new_space_->ReportStatistics();
PrintF("Old space : ");
old_space_->ReportStatistics();
PrintF("Code space : ");
code_space_->ReportStatistics();
PrintF("Map space : ");
map_space_->ReportStatistics();
PrintF("Large object space : ");
lo_space_->ReportStatistics();
PrintF(">>>>>> ========================================= >>>>>>\n");
}
#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::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));
}
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));
}
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);
}
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);
}
UNREACHABLE();
}
bool Heap::IsValidAllocationSpace(AllocationSpace space) {
switch (space) {
case NEW_SPACE:
case OLD_SPACE:
case CODE_SPACE:
case MAP_SPACE:
case LO_SPACE:
return true;
default:
return false;
}
}
bool Heap::RootIsImmortalImmovable(int root_index) {
switch (root_index) {
#define IMMORTAL_IMMOVABLE_ROOT(name) case Heap::k##name##RootIndex:
IMMORTAL_IMMOVABLE_ROOT_LIST(IMMORTAL_IMMOVABLE_ROOT)
#undef IMMORTAL_IMMOVABLE_ROOT
#define INTERNALIZED_STRING(name, value) case Heap::k##name##RootIndex:
INTERNALIZED_STRING_LIST(INTERNALIZED_STRING)
#undef INTERNALIZED_STRING
#define STRING_TYPE(NAME, size, name, Name) case Heap::k##Name##MapRootIndex:
STRING_TYPE_LIST(STRING_TYPE)
#undef STRING_TYPE
return true;
default:
return false;
}
}
#ifdef VERIFY_HEAP
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;
IterateRoots(&visitor, VISIT_ONLY_STRONG);
VerifySmisVisitor smis_visitor;
IterateSmiRoots(&smis_visitor);
new_space_->Verify();
old_space_->Verify(&visitor);
map_space_->Verify(&visitor);
VerifyPointersVisitor no_dirty_regions_visitor;
code_space_->Verify(&no_dirty_regions_visitor);
lo_space_->Verify();
mark_compact_collector()->VerifyWeakEmbeddedObjectsInCode();
}
class SlotVerifyingVisitor : public ObjectVisitor {
public:
SlotVerifyingVisitor(std::set<Address>* untyped,
std::set<std::pair<SlotType, Address> >* typed)
: untyped_(untyped), typed_(typed) {}
virtual bool ShouldHaveBeenRecorded(HeapObject* host, Object* target) = 0;
void VisitPointers(HeapObject* host, Object** start, Object** end) override {
for (Object** slot = start; slot < end; slot++) {
if (ShouldHaveBeenRecorded(host, *slot)) {
CHECK_GT(untyped_->count(reinterpret_cast<Address>(slot)), 0);
}
}
}
void VisitCodeTarget(Code* host, RelocInfo* rinfo) override {
Object* target = Code::GetCodeFromTargetAddress(rinfo->target_address());
if (ShouldHaveBeenRecorded(host, 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, 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<Address>* untyped_;
std::set<std::pair<SlotType, Address> >* typed_;
};
class OldToNewSlotVerifyingVisitor : public SlotVerifyingVisitor {
public:
OldToNewSlotVerifyingVisitor(Heap* heap, std::set<Address>* untyped,
std::set<std::pair<SlotType, Address> >* typed)
: SlotVerifyingVisitor(untyped, typed), heap_(heap) {}
bool ShouldHaveBeenRecorded(HeapObject* host, Object* target) override {
DCHECK_IMPLIES(target->IsHeapObject() && heap_->InNewSpace(target),
heap_->InToSpace(target));
return target->IsHeapObject() && heap_->InNewSpace(target) &&
!heap_->InNewSpace(host);
}
private:
Heap* heap_;
};
template <RememberedSetType direction>
void CollectSlots(MemoryChunk* chunk, Address start, Address end,
std::set<Address>* untyped,
std::set<std::pair<SlotType, Address> >* typed) {
RememberedSet<direction>::Iterate(chunk,
[start, end, untyped](Address slot) {
if (start <= slot && slot < end) {
untyped->insert(slot);
}
return KEEP_SLOT;
},
SlotSet::PREFREE_EMPTY_BUCKETS);
RememberedSet<direction>::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());
base::LockGuard<base::RecursiveMutex> lock_guard(chunk->mutex());
Address start = object->address();
Address end = start + object->Size();
std::set<Address> old_to_new;
std::set<std::pair<SlotType, Address> > typed_old_to_new;
if (!InNewSpace(object)) {
store_buffer()->MoveAllEntriesToRememberedSet();
CollectSlots<OLD_TO_NEW>(chunk, start, end, &old_to_new, &typed_old_to_new);
OldToNewSlotVerifyingVisitor visitor(this, &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_->FromSpaceStart(), new_space_->FromSpaceEnd())) {
for (Address cursor = page->area_start(), limit = page->area_end();
cursor < limit; cursor += kPointerSize) {
Memory::Address_at(cursor) = kFromSpaceZapValue;
}
}
}
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, reinterpret_cast<Object**>(
&roots_[kStringTableRootIndex]));
v->Synchronize(VisitorSynchronization::kStringTable);
if (!isMinorGC && mode != VISIT_ALL_IN_SWEEP_NEWSPACE) {
// Scavenge collections have special processing for this.
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, &roots_[kSmiRootsStart],
&roots_[kRootListLength]);
v->Synchronize(VisitorSynchronization::kSmiRootList);
}
void Heap::IterateEncounteredWeakCollections(RootVisitor* visitor) {
visitor->VisitRootPointer(Root::kWeakCollections,
&encountered_weak_collections_);
}
// 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, Object** p) override { FixHandle(p); }
void VisitRootPointers(Root root, 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<HeapObject*>(*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<Address>(current);
if (current->map() == heap_->one_pointer_filler_map()) {
next += kPointerSize;
} else if (current->map() == heap_->two_pointer_filler_map()) {
next += 2 * kPointerSize;
} else {
next += current->Size();
}
current = reinterpret_cast<HeapObject*>(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;
v->VisitRootPointers(Root::kStrongRootList, &roots_[0],
&roots_[kStrongRootListLength]);
v->Synchronize(VisitorSynchronization::kStrongRootList);
// The serializer/deserializer iterates the root list twice, first to pick
// off immortal immovable roots to make sure they end up on the first page,
// and then again for the rest.
if (mode == VISIT_ONLY_STRONG_ROOT_LIST) return;
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) {
isolate_->builtins()->IterateBuiltins(v);
v->Synchronize(VisitorSynchronization::kBuiltins);
isolate_->interpreter()->IterateDispatchTable(v);
v->Synchronize(VisitorSynchronization::kDispatchTable);
}
// Iterate over global handles.
switch (mode) {
case VISIT_ONLY_STRONG_ROOT_LIST:
UNREACHABLE();
break;
case VISIT_ONLY_STRONG_FOR_SERIALIZATION:
break;
case VISIT_ONLY_STRONG:
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 be the minor MC.
break;
case VISIT_ALL_IN_MINOR_MC_UPDATE:
// Global handles are processed manually be the minor MC.
break;
case VISIT_ALL_IN_SWEEP_NEWSPACE:
case VISIT_ALL:
isolate_->global_handles()->IterateAllRoots(v);
break;
}
v->Synchronize(VisitorSynchronization::kGlobalHandles);
// Iterate over eternal handles.
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, list->start, list->end);
}
v->Synchronize(VisitorSynchronization::kStrongRoots);
// Iterate over the partial snapshot cache unless serializing.
if (mode != VISIT_ONLY_STRONG_FOR_SERIALIZATION) {
SerializerDeserializer::Iterate(isolate_, v);
}
// We don't do a v->Synchronize call here, because in debug mode that will
// output a flag to the snapshot. However at this point the serializer and
// deserializer are deliberately a little unsynchronized (see above) so the
// checking of the sync flag in the snapshot would fail.
}
// 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.
bool 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) {
if (HasBeenSetUp()) return false;
// Overwrite default configuration.
if (max_semi_space_size_in_kb != 0) {
max_semi_space_size_ =
ROUND_UP(max_semi_space_size_in_kb * KB, Page::kPageSize);
}
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<size_t>(FLAG_max_semi_space_size) * MB;
}
if (FLAG_max_old_space_size > 0) {
max_old_generation_size_ =
static_cast<size_t>(FLAG_max_old_space_size) * MB;
}
if (Page::kPageSize > MB) {
max_semi_space_size_ = ROUND_UP(max_semi_space_size_, Page::kPageSize);
max_old_generation_size_ =
ROUND_UP(max_old_generation_size_, Page::kPageSize);
}
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_ = base::bits::RoundUpToPowerOfTwo32(
static_cast<uint32_t>(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<size_t>(1 * MB));
}
if (FLAG_min_semi_space_size > 0) {
size_t initial_semispace_size =
static_cast<size_t>(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_ =
ROUND_UP(initial_semispace_size, Page::kPageSize);
}
}
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_PAGED_SPACE - FIRST_PAGED_SPACE + 1;
initial_max_old_generation_size_ = max_old_generation_size_ =
Max(static_cast<size_t>(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;
return 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_);
}
bool Heap::ConfigureHeapDefault() { return ConfigureHeap(0, 0, 0); }
void Heap::RecordStats(HeapStats* stats, bool take_snapshot) {
*stats->start_marker = HeapStats::kStartMarker;
*stats->end_marker = HeapStats::kEndMarker;
*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 != NULL;
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 != NULL)
GetFromRingBuffer(stats->last_few_messages);
if (stats->js_stacktrace != NULL) {
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::PromotedSpaceSizeOfObjects() {
return old_space_->SizeOfObjects() + code_space_->SizeOfObjects() +
map_space_->SizeOfObjects() + lo_space_->SizeOfObjects();
}
uint64_t Heap::PromotedExternalMemorySize() {
if (external_memory_ <= external_memory_at_last_mark_compact_) return 0;
return static_cast<uint64_t>(external_memory_ -
external_memory_at_last_mark_compact_);
}
const double Heap::kMinHeapGrowingFactor = 1.1;
const double Heap::kMaxHeapGrowingFactor = 4.0;
const double Heap::kMaxHeapGrowingFactorMemoryConstrained = 2.0;
const double Heap::kMaxHeapGrowingFactorIdle = 1.5;
const double Heap::kConservativeHeapGrowingFactor = 1.3;
const double Heap::kTargetMutatorUtilization = 0.97;
// Given GC speed in bytes per ms, the allocation throughput in bytes per ms
// (mutator speed), this function returns the heap growing factor that will
// achieve the kTargetMutatorUtilisation if the GC speed and the mutator speed
// remain the same until the next GC.
//
// For a fixed time-frame T = TM + TG, the mutator utilization is the ratio
// TM / (TM + TG), where TM is the time spent in the mutator and TG is the
// time spent in the garbage collector.
//
// Let MU be kTargetMutatorUtilisation, the desired mutator utilization for the
// time-frame from the end of the current GC to the end of the next GC. Based
// on the MU we can compute the heap growing factor F as
//
// F = R * (1 - MU) / (R * (1 - MU) - MU), where R = gc_speed / mutator_speed.
//
// This formula can be derived as follows.
//
// F = Limit / Live by definition, where the Limit is the allocation limit,
// and the Live is size of live objects.
// Let’s assume that we already know the Limit. Then:
// TG = Limit / gc_speed
// TM = (TM + TG) * MU, by definition of MU.
// TM = TG * MU / (1 - MU)
// TM = Limit * MU / (gc_speed * (1 - MU))
// On the other hand, if the allocation throughput remains constant:
// Limit = Live + TM * allocation_throughput = Live + TM * mutator_speed
// Solving it for TM, we get
// TM = (Limit - Live) / mutator_speed
// Combining the two equation for TM:
// (Limit - Live) / mutator_speed = Limit * MU / (gc_speed * (1 - MU))
// (Limit - Live) = Limit * MU * mutator_speed / (gc_speed * (1 - MU))
// substitute R = gc_speed / mutator_speed
// (Limit - Live) = Limit * MU / (R * (1 - MU))
// substitute F = Limit / Live
// F - 1 = F * MU / (R * (1 - MU))
// F - F * MU / (R * (1 - MU)) = 1
// F * (1 - MU / (R * (1 - MU))) = 1
// F * (R * (1 - MU) - MU) / (R * (1 - MU)) = 1
// F = R * (1 - MU) / (R * (1 - MU) - MU)
double Heap::HeapGrowingFactor(double gc_speed, double mutator_speed,
double max_factor) {
DCHECK_LE(kMinHeapGrowingFactor, max_factor);
DCHECK_GE(kMaxHeapGrowingFactor, max_factor);
if (gc_speed == 0 || mutator_speed == 0) return max_factor;
const double speed_ratio = gc_speed / mutator_speed;
const double mu = kTargetMutatorUtilization;
const double a = speed_ratio * (1 - mu);
const double b = speed_ratio * (1 - mu) - mu;
// The factor is a / b, but we need to check for small b first.
double factor = (a < b * max_factor) ? a / b : max_factor;
factor = Min(factor, max_factor);
factor = Max(factor, kMinHeapGrowingFactor);
return factor;
}
double Heap::MaxHeapGrowingFactor(size_t max_old_generation_size) {
const double min_small_factor = 1.3;
const double max_small_factor = 2.0;
const double high_factor = 4.0;
size_t max_old_generation_size_in_mb = max_old_generation_size / MB;
max_old_generation_size_in_mb =
Max(max_old_generation_size_in_mb,
static_cast<size_t>(kMinOldGenerationSize));
// If we are on a device with lots of memory, we allow a high heap
// growing factor.
if (max_old_generation_size_in_mb >= kMaxOldGenerationSize) {
return high_factor;
}
DCHECK_GE(max_old_generation_size_in_mb, kMinOldGenerationSize);
DCHECK_LT(max_old_generation_size_in_mb, kMaxOldGenerationSize);
// On smaller devices we linearly scale the factor: (X-A)/(B-A)*(D-C)+C
double factor = (max_old_generation_size_in_mb - kMinOldGenerationSize) *
(max_small_factor - min_small_factor) /
(kMaxOldGenerationSize - kMinOldGenerationSize) +
min_small_factor;
return factor;
}
size_t Heap::CalculateOldGenerationAllocationLimit(double factor,
size_t old_gen_size) {
CHECK_LT(1.0, factor);
CHECK_LT(0, old_gen_size);
uint64_t limit = static_cast<uint64_t>(old_gen_size * factor);
limit = Max(limit, static_cast<uint64_t>(old_gen_size) +
MinimumAllocationLimitGrowingStep());
limit += new_space_->Capacity();
uint64_t halfway_to_the_max =
(static_cast<uint64_t>(old_gen_size) + max_old_generation_size_) / 2;
return static_cast<size_t>(Min(limit, halfway_to_the_max));
}
size_t Heap::MinimumAllocationLimitGrowingStep() {
const size_t kRegularAllocationLimitGrowingStep = 8;
const size_t kLowMemoryAllocationLimitGrowingStep = 2;
size_t limit = (Page::kPageSize > MB ? Page::kPageSize : MB);
return limit * (ShouldOptimizeForMemoryUsage()
? kLowMemoryAllocationLimitGrowingStep
: kRegularAllocationLimitGrowingStep);
}
void Heap::SetOldGenerationAllocationLimit(size_t old_gen_size, double gc_speed,
double mutator_speed) {
double max_factor = MaxHeapGrowingFactor(max_old_generation_size_);
double factor = HeapGrowingFactor(gc_speed, mutator_speed, max_factor);
if (FLAG_trace_gc_verbose) {
isolate_->PrintWithTimestamp(
"Heap growing factor %.1f based on mu=%.3f, speed_ratio=%.f "
"(gc=%.f, mutator=%.f)\n",
factor, kTargetMutatorUtilization, gc_speed / mutator_speed, gc_speed,
mutator_speed);
}
if (memory_reducer_->ShouldGrowHeapSlowly() ||
ShouldOptimizeForMemoryUsage()) {
factor = Min(factor, kConservativeHeapGrowingFactor);
}
if (FLAG_stress_compaction || ShouldReduceMemory()) {
factor = kMinHeapGrowingFactor;
}
if (FLAG_heap_growing_percent > 0) {
factor = 1.0 + FLAG_heap_growing_percent / 100.0;
}
old_generation_allocation_limit_ =
CalculateOldGenerationAllocationLimit(factor, old_gen_size);
if (FLAG_trace_gc_verbose) {
isolate_->PrintWithTimestamp(
"Grow: old size: %" PRIuS " KB, new limit: %" PRIuS " KB (%.1f)\n",
old_gen_size / KB, old_generation_allocation_limit_ / KB, factor);
}
}
void Heap::DampenOldGenerationAllocationLimit(size_t old_gen_size,
double gc_speed,
double mutator_speed) {
double max_factor = MaxHeapGrowingFactor(max_old_generation_size_);
double factor = HeapGrowingFactor(gc_speed, mutator_speed, max_factor);
size_t limit = CalculateOldGenerationAllocationLimit(factor, old_gen_size);
if (limit < old_generation_allocation_limit_) {
if (FLAG_trace_gc_verbose) {
isolate_->PrintWithTimestamp(
"Dampen: old size: %" PRIuS " KB, old limit: %" PRIuS
" KB, "
"new limit: %" PRIuS " KB (%.1f)\n",
old_gen_size / KB, old_generation_allocation_limit_ / KB, limit / KB,
factor);
}
old_generation_allocation_limit_ = limit;
}
}
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;
}
// 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 (PromotedSpaceSizeOfObjects() <=
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;
}
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);
for (PagedSpace* space = spaces.next(); space != NULL;
space = spaces.next()) {
space->EmptyAllocationInfo();
}
}
bool Heap::SetUp() {
#ifdef DEBUG
allocation_timeout_ = FLAG_gc_interval;
#endif
// Initialize heap spaces and initial maps and objects. Whenever something
// goes wrong, just return false. The caller should check the results and
// call Heap::TearDown() to release allocated memory.
//
// 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_) {
if (!ConfigureHeapDefault()) return false;
}
mmap_region_base_ =
reinterpret_cast<uintptr_t>(v8::internal::GetRandomMmapAddr()) &
~kMmapRegionMask;
// Set up memory allocator.
memory_allocator_ = new MemoryAllocator(isolate_);
if (!memory_allocator_->SetUp(MaxReserved(), code_range_size_)) return false;
store_buffer_ = new StoreBuffer(this);
mark_compact_collector_ = new MarkCompactCollector(this);
incremental_marking_ = new IncrementalMarking(this);
incremental_marking_->set_marking_worklist(
mark_compact_collector_->marking_worklist());
if (FLAG_concurrent_marking) {
MarkCompactCollector::MarkingWorklist* marking_worklist =
mark_compact_collector_->marking_worklist();
concurrent_marking_ = new ConcurrentMarking(
this, marking_worklist->shared(), marking_worklist->bailout(),
mark_compact_collector_->weak_objects());
} else {
concurrent_marking_ =
new ConcurrentMarking(this, nullptr, nullptr, nullptr);
}
for (int i = 0; i <= LAST_SPACE; i++) {
space_[i] = nullptr;
}
space_[NEW_SPACE] = new_space_ = new NewSpace(this);
if (!new_space_->SetUp(initial_semispace_size_, max_semi_space_size_)) {
return false;
}
new_space_top_after_last_gc_ = new_space()->top();
space_[OLD_SPACE] = old_space_ =
new OldSpace(this, OLD_SPACE, NOT_EXECUTABLE);
if (!old_space_->SetUp()) return false;
space_[CODE_SPACE] = code_space_ = new OldSpace(this, CODE_SPACE, EXECUTABLE);
if (!code_space_->SetUp()) return false;
space_[MAP_SPACE] = map_space_ = new MapSpace(this, MAP_SPACE);
if (!map_space_->SetUp()) return false;
// The large object code space may contain code or data. We set the memory
// to be non-executable here for safety, but this means we need to enable it
// explicitly when allocating large code objects.
space_[LO_SPACE] = lo_space_ = new LargeObjectSpace(this, LO_SPACE);
if (!lo_space_->SetUp()) return false;
// Set up the seed that is used to randomize the string hash function.
DCHECK_EQ(Smi::kZero, hash_seed());
if (FLAG_randomize_hashes) InitializeHashSeed();
for (int i = 0; i < static_cast<int>(v8::Isolate::kUseCounterFeatureCount);
i++) {
deferred_counters_[i] = 0;
}
tracer_ = new GCTracer(this);
minor_mark_compact_collector_ = new MinorMarkCompactCollector(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();
LOG(isolate_, IntPtrTEvent("heap-capacity", Capacity()));
LOG(isolate_, IntPtrTEvent("heap-available", Available()));
store_buffer()->SetUp();
mark_compact_collector()->SetUp();
if (minor_mark_compact_collector() != nullptr) {
minor_mark_compact_collector()->SetUp();
}
idle_scavenge_observer_ = new IdleScavengeObserver(
*this, ScavengeJob::kBytesAllocatedBeforeNextIdleTask);
new_space()->AddAllocationObserver(idle_scavenge_observer_);
SetGetExternallyAllocatedMemoryInBytesCallback(
DefaultGetExternallyAllocatedMemoryInBytesCallback);
return true;
}
void Heap::InitializeHashSeed() {
if (FLAG_hash_seed == 0) {
int rnd = isolate()->random_number_generator()->NextInt();
set_hash_seed(Smi::FromInt(rnd & Name::kHashBitMask));
} else {
set_hash_seed(Smi::FromInt(FLAG_hash_seed));
}
}
void Heap::SetStackLimits() {
DCHECK(isolate_ != NULL);
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_[kStackLimitRootIndex] = reinterpret_cast<Object*>(
(isolate_->stack_guard()->jslimit() & ~kSmiTagMask) | kSmiTag);
roots_[kRealStackLimitRootIndex] = reinterpret_cast<Object*>(
(isolate_->stack_guard()->real_jslimit() & ~kSmiTagMask) | kSmiTag);
}
void Heap::ClearStackLimits() {
roots_[kStackLimitRootIndex] = Smi::kZero;
roots_[kRealStackLimitRootIndex] = Smi::kZero;
}
void Heap::PrintAllocationsHash() {
uint32_t hash = StringHasher::GetHashCore(raw_allocations_hash_);
PrintF("\n### Allocations = %u, hash = 0x%08x\n", allocations_count(), hash);
}
void Heap::NotifyDeserializationComplete() {
PagedSpaces spaces(this);
for (PagedSpace* s = spaces.next(); s != NULL; 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
}
deserialization_complete_ = true;
}
void Heap::SetEmbedderHeapTracer(EmbedderHeapTracer* tracer) {
DCHECK_EQ(gc_state_, HeapState::NOT_IN_GC);
local_embedder_heap_tracer()->SetRemoteTracer(tracer);
}
void Heap::TracePossibleWrapper(JSObject* js_object) {
DCHECK(js_object->WasConstructedFromApiFunction());
if (js_object->GetEmbedderFieldCount() >= 2 &&
js_object->GetEmbedderField(0) &&
js_object->GetEmbedderField(0) != undefined_value() &&
js_object->GetEmbedderField(1) != undefined_value()) {
DCHECK_EQ(0,
reinterpret_cast<intptr_t>(js_object->GetEmbedderField(0)) % 2);
local_embedder_heap_tracer()->AddWrapperToTrace(std::pair<void*, void*>(
reinterpret_cast<void*>(js_object->GetEmbedderField(0)),
reinterpret_cast<void*>(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::TearDown() {
use_tasks_ = false;
#ifdef VERIFY_HEAP
if (FLAG_verify_heap) {
Verify();
}
#endif
UpdateMaximumCommitted();
if (FLAG_verify_predictable) {
PrintAllocationsHash();
}
new_space()->RemoveAllocationObserver(idle_scavenge_observer_);
delete idle_scavenge_observer_;
idle_scavenge_observer_ = nullptr;
if (mark_compact_collector_ != nullptr) {
mark_compact_collector_->TearDown();
delete mark_compact_collector_;
mark_compact_collector_ = nullptr;
}
if (minor_mark_compact_collector_ != nullptr) {
minor_mark_compact_collector_->TearDown();
delete minor_mark_compact_collector_;
minor_mark_compact_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();
delete tracer_;
tracer_ = nullptr;
new_space_->TearDown();
delete new_space_;
new_space_ = nullptr;
if (old_space_ != NULL) {
delete old_space_;
old_space_ = NULL;
}
if (code_space_ != NULL) {
delete code_space_;
code_space_ = NULL;
}
if (map_space_ != NULL) {
delete map_space_;
map_space_ = NULL;
}
if (lo_space_ != NULL) {
lo_space_->TearDown();
delete lo_space_;
lo_space_ = NULL;
}
store_buffer()->TearDown();
memory_allocator()->TearDown();
StrongRootsList* next = NULL;
for (StrongRootsList* list = strong_roots_list_; list; list = next) {
next = list->next;
delete list;
}
strong_roots_list_ = NULL;
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();
}
// TODO(ishell): Find a better place for this.
void Heap::AddWeakNewSpaceObjectToCodeDependency(Handle<HeapObject> obj,
Handle<WeakCell> code) {
DCHECK(InNewSpace(*obj));
DCHECK(!InNewSpace(*code));
Handle<ArrayList> list(weak_new_space_object_to_code_list(), isolate());
list = ArrayList::Add(list, isolate()->factory()->NewWeakCell(obj), code);
if (*list != weak_new_space_object_to_code_list()) {
set_weak_new_space_object_to_code_list(*list);
}
}
// TODO(ishell): Find a better place for this.
void Heap::AddWeakObjectToCodeDependency(Handle<HeapObject> obj,
Handle<DependentCode> dep) {
DCHECK(!InNewSpace(*obj));
DCHECK(!InNewSpace(*dep));
Handle<WeakHashTable> table(weak_object_to_code_table(), isolate());
table = WeakHashTable::Put(table, obj, dep);
if (*table != weak_object_to_code_table())
set_weak_object_to_code_table(*table);
DCHECK_EQ(*dep, LookupWeakObjectToCodeDependency(obj));
}
DependentCode* Heap::LookupWeakObjectToCodeDependency(Handle<HeapObject> obj) {
Object* dep = weak_object_to_code_table()->Lookup(obj);
if (dep->IsDependentCode()) return DependentCode::cast(dep);
return DependentCode::cast(empty_fixed_array());
}
namespace {
void CompactWeakFixedArray(Object* object) {
if (object->IsWeakFixedArray()) {
WeakFixedArray* array = WeakFixedArray::cast(object);
array->Compact<WeakFixedArray::NullCallback>();
}
}
} // anonymous namespace
void Heap::CompactWeakFixedArrays() {
// Find known WeakFixedArrays and compact them.
HeapIterator iterator(this);
for (HeapObject* o = iterator.next(); o != NULL; o = iterator.next()) {
if (o->IsPrototypeInfo()) {
Object* prototype_users = PrototypeInfo::cast(o)->prototype_users();
if (prototype_users->IsWeakFixedArray()) {
WeakFixedArray* array = WeakFixedArray::cast(prototype_users);
array->Compact<JSObject::PrototypeRegistryCompactionCallback>();
}
}
}
CompactWeakFixedArray(noscript_shared_function_infos());
CompactWeakFixedArray(script_list());
CompactWeakFixedArray(weak_stack_trace_list());
}
void Heap::AddRetainedMap(Handle<Map> map) {
Handle<WeakCell> cell = Map::WeakCellForMap(map);
Handle<ArrayList> array(retained_maps(), isolate());
if (array->IsFull()) {
CompactRetainedMaps(*array);
}
array = ArrayList::Add(
array, cell, handle(Smi::FromInt(FLAG_retain_maps_for_n_gc), isolate()),
ArrayList::kReloadLengthAfterAllocation);
if (*array != retained_maps()) {
set_retained_maps(*array);
}
}
void Heap::CompactRetainedMaps(ArrayList* 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) {
DCHECK(retained_maps->Get(i)->IsWeakCell());
WeakCell* cell = WeakCell::cast(retained_maps->Get(i));
Object* age = retained_maps->Get(i + 1);
if (cell->cleared()) continue;
if (i != new_length) {
retained_maps->Set(new_length, cell);
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;
Object* undefined = undefined_value();
for (int i = new_length; i < length; i++) {
retained_maps->Clear(i, undefined);
}
if (new_length != length) retained_maps->SetLength(new_length);
}
void Heap::FatalProcessOutOfMemory(const char* location, bool is_heap_oom) {
v8::internal::V8::FatalProcessOutOfMemory(location, is_heap_oom);
}
#ifdef DEBUG
class PrintHandleVisitor : public RootVisitor {
public:
void VisitRootPointers(Root root, Object** start, Object** end) override {
for (Object** p = start; p < end; p++)
PrintF(" handle %p to %p\n", reinterpret_cast<void*>(p),
reinterpret_cast<void*>(*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, 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);
}
void Heap::ClearRecordedSlot(HeapObject* object, Object** slot) {
Address slot_addr = reinterpret_cast<Address>(slot);
Page* page = Page::FromAddress(slot_addr);
if (!page->InNewSpace()) {
DCHECK_EQ(page->owner()->identity(), OLD_SPACE);
store_buffer()->DeleteEntry(slot_addr);
}
}
bool Heap::HasRecordedSlot(HeapObject* object, Object** slot) {
if (InNewSpace(object)) {
return false;
}
Address slot_addr = reinterpret_cast<Address>(slot);
Page* page = Page::FromAddress(slot_addr);
DCHECK_EQ(page->owner()->identity(), OLD_SPACE);
store_buffer()->MoveAllEntriesToRememberedSet();
return RememberedSet<OLD_TO_NEW>::Contains(page, slot_addr) ||
RememberedSet<OLD_TO_OLD>::Contains(page, slot_addr);
}
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);
}
}
void Heap::RecordWriteIntoCodeSlow(Code* host, RelocInfo* rinfo,
Object* value) {
DCHECK(InNewSpace(value));
Page* source_page = Page::FromAddress(reinterpret_cast<Address>(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::IsCodeTarget(rmode)) {
slot_type = CODE_ENTRY_SLOT;
} else {
DCHECK(RelocInfo::IsEmbeddedObject(rmode));
slot_type = OBJECT_SLOT;
}
}
RememberedSet<OLD_TO_NEW>::InsertTyped(
source_page, reinterpret_cast<Address>(host), slot_type, addr);
}
void Heap::RecordWritesIntoCode(Code* code) {
for (RelocIterator it(code, RelocInfo::ModeMask(RelocInfo::EMBEDDED_OBJECT));
!it.done(); it.next()) {
RecordWriteIntoCode(code, it.rinfo(), it.rinfo()->target_object());
}
}
Space* AllSpaces::next() {
switch (counter_++) {
case NEW_SPACE:
return heap_->new_space();
case OLD_SPACE:
return heap_->old_space();
case CODE_SPACE:
return heap_->code_space();
case MAP_SPACE:
return heap_->map_space();
case LO_SPACE:
return heap_->lo_space();
default:
return NULL;
}
}
PagedSpace* PagedSpaces::next() {
switch (counter_++) {
case OLD_SPACE:
return heap_->old_space();
case CODE_SPACE:
return heap_->code_space();
case MAP_SPACE:
return heap_->map_space();
default:
return NULL;
}
}
OldSpace* OldSpaces::next() {
switch (counter_++) {
case OLD_SPACE:
return heap_->old_space();
case CODE_SPACE:
return heap_->code_space();
default:
return NULL;
}
}
SpaceIterator::SpaceIterator(Heap* heap)
: heap_(heap), current_space_(FIRST_SPACE - 1) {}
SpaceIterator::~SpaceIterator() {
}
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() {}
virtual bool SkipObject(HeapObject* object) = 0;
};
class UnreachableObjectsFilter : public HeapObjectsFilter {
public:
explicit UnreachableObjectsFilter(Heap* heap) : heap_(heap) {
MarkReachableObjects();
}
~UnreachableObjectsFilter() {
for (auto it : reachable_) {
delete it.second;
it.second = nullptr;
}
}
bool SkipObject(HeapObject* object) {
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<HeapObject*>();
}
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(start, end);
}
void VisitRootPointers(Root root, Object** start, Object** end) override {
MarkPointers(start, end);
}
void TransitiveClosure() {
while (!marking_stack_.empty()) {
HeapObject* obj = marking_stack_.back();
marking_stack_.pop_back();
obj->Iterate(this);
}
}
private:
void MarkPointers(Object** start, Object** end) {
for (Object** p = start; p < end; p++) {
if (!(*p)->IsHeapObject()) continue;
HeapObject* obj = HeapObject::cast(*p);
if (filter_->MarkAsReachable(obj)) {
marking_stack_.push_back(obj);
}
}
}
UnreachableObjectsFilter* filter_;
std::vector<HeapObject*> marking_stack_;
};
friend class MarkingVisitor;
void MarkReachableObjects() {
MarkingVisitor visitor(this);
heap_->IterateRoots(&visitor, VISIT_ALL);
visitor.TransitiveClosure();
}
Heap* heap_;
DisallowHeapAllocation no_allocation_;
std::unordered_map<MemoryChunk*, std::unordered_set<HeapObject*>*> 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;
}
if (o->IsThinString()) {
o = ThinString::cast(o)->actual();
if (!o->IsExternalString()) continue;
}
DCHECK(o->IsExternalString());
if (heap_->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;
}
if (o->IsThinString()) {
o = ThinString::cast(o)->actual();
if (!o->IsExternalString()) continue;
}
DCHECK(o->IsExternalString());
DCHECK(!heap_->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];
if (o->IsThinString()) {
o = ThinString::cast(o)->actual();
if (!o->IsExternalString()) 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];
if (o->IsThinString()) {
o = ThinString::cast(o)->actual();
if (!o->IsExternalString()) continue;
}
heap_->FinalizeExternalString(ExternalString::cast(o));
}
old_space_strings_.clear();
}
void Heap::RememberUnmappedPage(Address page, bool compacted) {
uintptr_t p = reinterpret_cast<uintptr_t>(page);
// Tag the page pointer to make it findable in the dump file.
if (compacted) {
p ^= 0xc1ead & (Page::kPageSize - 1); // Cleared.
} else {
p ^= 0x1d1ed & (Page::kPageSize - 1); // I died.
}
remembered_unmapped_pages_[remembered_unmapped_pages_index_] =
reinterpret_cast<Address>(p);
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 = NULL;
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;
}
}
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<int>(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_CODE_KIND_SUB_TYPE + Code::name: \
*object_type = "CODE_TYPE"; \
*object_sub_type = "CODE_KIND/" #name; \
return true;
CODE_KIND_LIST(COMPARE_AND_RETURN_NAME)
#undef COMPARE_AND_RETURN_NAME
#define COMPARE_AND_RETURN_NAME(name) \
case ObjectStats::FIRST_FIXED_ARRAY_SUB_TYPE + name: \
*object_type = "FIXED_ARRAY_TYPE"; \
*object_sub_type = #name; \
return true;
FIXED_ARRAY_SUB_INSTANCE_TYPE_LIST(COMPARE_AND_RETURN_NAME)
#undef COMPARE_AND_RETURN_NAME
}
return false;
}
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";
default:
UNREACHABLE();
}
return NULL;
}
void VerifyPointersVisitor::VisitPointers(HeapObject* host, Object** start,
Object** end) {
VerifyPointers(start, end);
}
void VerifyPointersVisitor::VisitRootPointers(Root root, Object** start,
Object** end) {
VerifyPointers(start, end);
}
void VerifyPointersVisitor::VerifyPointers(Object** start, Object** end) {
for (Object** current = start; current < end; current++) {
if ((*current)->IsHeapObject()) {
HeapObject* object = HeapObject::cast(*current);
CHECK(object->GetIsolate()->heap()->Contains(object));
CHECK(object->map()->IsMap());
} else {
CHECK((*current)->IsSmi());
}
}
}
void VerifySmisVisitor::VisitRootPointers(Root root, 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() == 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 == src || dst == OLD_SPACE;
case OLD_SPACE:
return dst == src &&
(dst == OLD_SPACE || obj->IsFiller() || obj->IsExternalString());
case CODE_SPACE:
return dst == src && type == CODE_TYPE;
case MAP_SPACE:
case LO_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);
}
}
} // namespace internal
} // namespace v8