// 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 "src/accessors.h"
#include "src/api.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/global-handles.h"
#include "src/heap/array-buffer-tracker-inl.h"
#include "src/heap/code-stats.h"
#include "src/heap/gc-idle-time-handler.h"
#include "src/heap/gc-tracer.h"
#include "src/heap/incremental-marking.h"
#include "src/heap/mark-compact-inl.h"
#include "src/heap/mark-compact.h"
#include "src/heap/memory-reducer.h"
#include "src/heap/object-stats.h"
#include "src/heap/objects-visiting-inl.h"
#include "src/heap/objects-visiting.h"
#include "src/heap/remembered-set.h"
#include "src/heap/scavenge-job.h"
#include "src/heap/scavenger-inl.h"
#include "src/heap/store-buffer.h"
#include "src/interpreter/interpreter.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/type-feedback-vector.h"
#include "src/utils.h"
#include "src/v8.h"
#include "src/v8threads.h"
#include "src/vm-state-inl.h"
namespace v8 {
namespace internal {
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_(MB),
max_old_generation_size_(700ul * (kPointerSize / 4) * MB),
initial_old_generation_size_(max_old_generation_size_ /
kInitalOldGenerationLimitFactor),
old_generation_size_configured_(false),
max_executable_size_(256ul * (kPointerSize / 4) * MB),
// 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),
contexts_disposed_(0),
number_of_disposed_maps_(0),
global_ic_age_(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),
remembered_unmapped_pages_index_(0),
#ifdef DEBUG
allocation_timeout_(0),
#endif // DEBUG
old_generation_allocation_limit_(initial_old_generation_size_),
inline_allocation_disabled_(false),
total_regexp_code_generated_(0),
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),
scavenge_collector_(nullptr),
mark_compact_collector_(nullptr),
memory_allocator_(nullptr),
store_buffer_(nullptr),
incremental_marking_(nullptr),
gc_idle_time_handler_(nullptr),
memory_reducer_(nullptr),
live_object_stats_(nullptr),
dead_object_stats_(nullptr),
scavenge_job_(nullptr),
idle_scavenge_observer_(nullptr),
full_codegen_bytes_generated_(0),
crankshaft_codegen_bytes_generated_(0),
new_space_allocation_counter_(0),
old_generation_allocation_counter_at_last_gc_(0),
old_generation_size_at_last_gc_(0),
gcs_since_last_deopt_(0),
global_pretenuring_feedback_(nullptr),
ring_buffer_full_(false),
ring_buffer_end_(0),
promotion_queue_(this),
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),
embedder_heap_tracer_(nullptr),
force_oom_(false),
delay_sweeper_tasks_for_testing_(false) {
// Allow build-time customization of the max semispace size. Building
// V8 with snapshots and a non-default max semispace size is much
// easier if you can define it as part of the build environment.
#if defined(V8_MAX_SEMISPACE_SIZE)
max_semi_space_size_ = reserved_semispace_size_ = V8_MAX_SEMISPACE_SIZE;
#endif
// Ensure old_generation_size_ is a multiple of kPageSize.
DCHECK((max_old_generation_size_ & (Page::kPageSize - 1)) == 0);
memset(roots_, 0, sizeof(roots_[0]) * kRootListLength);
set_native_contexts_list(NULL);
set_allocation_sites_list(Smi::kZero);
set_encountered_weak_collections(Smi::kZero);
set_encountered_weak_cells(Smi::kZero);
set_encountered_transition_arrays(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();
}
// 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_, "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::IncrementDeferredCount(v8::Isolate::UseCounterFeature feature) {
deferred_counters_[feature]++;
}
bool Heap::UncommitFromSpace() { return new_space_->UncommitFromSpace(); }
void Heap::GarbageCollectionPrologue() {
{
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();
store_buffer()->MoveAllEntriesToRememberedSet();
}
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::RepairFreeListsAfterDeserialization() {
PagedSpaces spaces(this);
for (PagedSpace* space = spaces.next(); space != NULL;
space = spaces.next()) {
space->RepairFreeListsAfterDeserialization();
}
}
void Heap::MergeAllocationSitePretenuringFeedback(
const base::HashMap& local_pretenuring_feedback) {
AllocationSite* site = nullptr;
for (base::HashMap::Entry* local_entry = local_pretenuring_feedback.Start();
local_entry != nullptr;
local_entry = local_pretenuring_feedback.Next(local_entry)) {
site = reinterpret_cast<AllocationSite*>(local_entry->key);
MapWord map_word = site->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;
int value =
static_cast<int>(reinterpret_cast<intptr_t>(local_entry->value));
DCHECK_GT(value, 0);
if (site->IncrementMementoFoundCount(value)) {
global_pretenuring_feedback_->LookupOrInsert(site,
ObjectHash(site->address()));
}
}
}
class Heap::PretenuringScope {
public:
explicit PretenuringScope(Heap* heap) : heap_(heap) {
heap_->global_pretenuring_feedback_ =
new base::HashMap(kInitialFeedbackCapacity);
}
~PretenuringScope() {
delete heap_->global_pretenuring_feedback_;
heap_->global_pretenuring_feedback_ = nullptr;
}
private:
Heap* heap_;
};
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 (base::HashMap::Entry* e = global_pretenuring_feedback_->Start();
e != nullptr; e = global_pretenuring_feedback_->Next(e)) {
allocation_sites++;
site = reinterpret_cast<AllocationSite*>(e->key);
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 (site->DigestPretenuringFeedback(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);
}
}
}
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() {
// 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
if (FLAG_deopt_every_n_garbage_collections > 0) {
// TODO(jkummerow/ulan/jarin): This is not safe! We can't assume that
// the topmost optimized frame can be deoptimized safely, because it
// might not have a lazy bailout point right after its current PC.
if (++gcs_since_last_deopt_ == FLAG_deopt_every_n_garbage_collections) {
Deoptimizer::DeoptimizeAll(isolate());
gcs_since_last_deopt_ = 0;
}
}
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_fraction_new_space()->AddSample(static_cast<int>(
(new_space()->CommittedMemory() * 100.0) / CommittedMemory()));
isolate_->counters()->heap_fraction_old_space()->AddSample(static_cast<int>(
(old_space()->CommittedMemory() * 100.0) / CommittedMemory()));
isolate_->counters()->heap_fraction_code_space()->AddSample(
static_cast<int>((code_space()->CommittedMemory() * 100.0) /
CommittedMemory()));
isolate_->counters()->heap_fraction_map_space()->AddSample(static_cast<int>(
(map_space()->CommittedMemory() * 100.0) / CommittedMemory()));
isolate_->counters()->heap_fraction_lo_space()->AddSample(static_cast<int>(
(lo_space()->CommittedMemory() * 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();
ReduceNewSpaceSize();
}
void Heap::PreprocessStackTraces() {
WeakFixedArray::Iterator iterator(weak_stack_trace_list());
FixedArray* elements;
while ((elements = iterator.Next<FixedArray>())) {
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::cast(elements->get(j + 3))->value();
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 (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(MARK_COMPACTOR, gc_reason, NULL,
v8::kGCCallbackFlagCollectAllAvailableGarbage) &&
attempt + 1 >= kMinNumberOfAttempts) {
break;
}
}
set_current_gc_flags(kNoGCFlags);
new_space_->Shrink();
UncommitFromSpace();
}
void Heap::ReportExternalMemoryPressure() {
if (external_memory_ >
(external_memory_at_last_mark_compact_ + external_memory_hard_limit())) {
CollectAllGarbage(
kReduceMemoryFootprintMask | kFinalizeIncrementalMarkingMask,
GarbageCollectionReason::kExternalMemoryPressure,
static_cast<GCCallbackFlags>(kGCCallbackFlagCollectAllAvailableGarbage |
kGCCallbackFlagCollectAllExternalMemory));
return;
}
if (incremental_marking()->IsStopped()) {
if (incremental_marking()->CanBeActivated()) {
StartIncrementalMarking(
i::Heap::kNoGCFlags, GarbageCollectionReason::kExternalMemoryPressure,
static_cast<GCCallbackFlags>(
kGCCallbackFlagSynchronousPhantomCallbackProcessing |
kGCCallbackFlagCollectAllExternalMemory));
} else {
CollectAllGarbage(i::Heap::kNoGCFlags,
GarbageCollectionReason::kExternalMemoryPressure,
kGCCallbackFlagSynchronousPhantomCallbackProcessing);
}
} else {
// Incremental marking is turned on an has already been started.
const double pressure =
static_cast<double>(external_memory_ -
external_memory_at_last_mark_compact_ -
kExternalAllocationSoftLimit) /
external_memory_hard_limit();
DCHECK_GE(1, pressure);
const double kMaxStepSizeOnExternalLimit = 25;
const double deadline = MonotonicallyIncreasingTimeInMs() +
pressure * kMaxStepSizeOnExternalLimit;
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(GarbageCollector collector,
GarbageCollectionReason gc_reason,
const char* collector_reason,
const v8::GCCallbackFlags gc_callback_flags) {
// The VM is in the GC state until exiting this function.
VMState<GC> state(isolate_);
#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");
}
}
if (collector == MARK_COMPACTOR && FLAG_incremental_marking &&
!ShouldFinalizeIncrementalMarking() && !ShouldAbortIncrementalMarking() &&
!incremental_marking()->IsStopped() &&
!incremental_marking()->should_hurry() &&
!incremental_marking()->NeedsFinalization() &&
!IsCloseToOutOfMemory(new_space_->Capacity())) {
if (!incremental_marking()->IsComplete() &&
!mark_compact_collector()->marking_deque()->IsEmpty() &&
!FLAG_gc_global) {
if (FLAG_trace_incremental_marking) {
isolate()->PrintWithTimestamp(
"[IncrementalMarking] Delaying MarkSweep.\n");
}
collector = YoungGenerationCollector();
collector_reason = "incremental marking delaying mark-sweep";
}
}
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);
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,
kNoGCCallbackFlags);
}
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);
}
AgeInlineCaches();
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) {
gc_idle_time_handler_->ResetNoProgressCounter();
StartIncrementalMarking(kReduceMemoryFootprintMask, gc_reason,
kNoGCCallbackFlags);
}
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_objects = array->data_start() + dst_index;
MemMove(dst_objects, array->data_start() + src_index, 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(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, List<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->length());
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_EQ(1, reservation->length());
int num_maps = reservation->at(0).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, ClearBlackArea::kNo);
maps->Add(free_space_address);
} else {
perform_gc = true;
break;
}
}
} else if (space == LO_SPACE) {
// Just check that we can allocate during deserialization.
DCHECK_EQ(1, reservation->length());
perform_gc = !CanExpandOldGeneration(reservation->at(0).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, ClearBlackArea::kNo);
DCHECK(space < SerializerDeserializer::kNumberOfPreallocatedSpaces);
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::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::PretenuringScope pretenuring_scope(this);
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:
Scavenge();
break;
}
ProcessPretenuringFeedback();
}
UpdateSurvivalStatistics(start_new_space_size);
ConfigureInitialOldGenerationSize();
isolate_->counters()->objs_since_last_young()->Set(0);
gc_post_processing_depth_++;
{
AllowHeapAllocation allow_allocation;
TRACE_GC(tracer(), GCTracer::Scope::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::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) {
for (int i = 0; i < gc_prologue_callbacks_.length(); ++i) {
if (gc_type & gc_prologue_callbacks_[i].gc_type) {
if (!gc_prologue_callbacks_[i].pass_isolate) {
v8::GCCallback callback = reinterpret_cast<v8::GCCallback>(
gc_prologue_callbacks_[i].callback);
callback(gc_type, flags);
} else {
v8::Isolate* isolate = reinterpret_cast<v8::Isolate*>(this->isolate());
gc_prologue_callbacks_[i].callback(isolate, gc_type, flags);
}
}
}
if (FLAG_trace_object_groups && (gc_type == kGCTypeIncrementalMarking ||
gc_type == kGCTypeMarkSweepCompact)) {
isolate_->global_handles()->PrintObjectGroups();
}
}
void Heap::CallGCEpilogueCallbacks(GCType gc_type,
GCCallbackFlags gc_callback_flags) {
for (int i = 0; i < gc_epilogue_callbacks_.length(); ++i) {
if (gc_type & gc_epilogue_callbacks_[i].gc_type) {
if (!gc_epilogue_callbacks_[i].pass_isolate) {
v8::GCCallback callback = reinterpret_cast<v8::GCCallback>(
gc_epilogue_callbacks_[i].callback);
callback(gc_type, gc_callback_flags);
} else {
v8::Isolate* isolate = reinterpret_cast<v8::Isolate*>(this->isolate());
gc_epilogue_callbacks_[i].callback(isolate, gc_type, gc_callback_flags);
}
}
}
}
void Heap::MarkCompact() {
PauseAllocationObserversScope pause_observers(this);
gc_state_ = 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() { UNREACHABLE(); }
void Heap::MarkCompactEpilogue() {
TRACE_GC(tracer(), GCTracer::Scope::MC_EPILOGUE);
gc_state_ = NOT_IN_GC;
isolate_->counters()->objs_since_last_full()->Set(0);
incremental_marking()->Epilogue();
PreprocessStackTraces();
DCHECK(incremental_marking()->IsStopped());
mark_compact_collector()->marking_deque()->StopUsing();
}
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();
CompletelyClearInstanceofCache();
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();
}
static bool IsUnmodifiedHeapObject(Object** p) {
Object* object = *p;
if (object->IsSmi()) return false;
HeapObject* heap_object = HeapObject::cast(object);
if (!object->IsJSObject()) return false;
JSObject* js_object = JSObject::cast(object);
if (!js_object->WasConstructedFromApiFunction()) return false;
JSFunction* constructor =
JSFunction::cast(js_object->map()->GetConstructor());
return constructor->initial_map() == heap_object->map();
}
void PromotionQueue::Initialize() {
// The last to-space page may be used for promotion queue. On promotion
// conflict, we use the emergency stack.
DCHECK((Page::kPageSize - MemoryChunk::kBodyOffset) % (2 * kPointerSize) ==
0);
front_ = rear_ =
reinterpret_cast<struct Entry*>(heap_->new_space()->ToSpaceEnd());
limit_ = reinterpret_cast<struct Entry*>(
Page::FromAllocationAreaAddress(reinterpret_cast<Address>(rear_))
->area_start());
emergency_stack_ = NULL;
}
void PromotionQueue::Destroy() {
DCHECK(is_empty());
delete emergency_stack_;
emergency_stack_ = NULL;
}
void PromotionQueue::RelocateQueueHead() {
DCHECK(emergency_stack_ == NULL);
Page* p = Page::FromAllocationAreaAddress(reinterpret_cast<Address>(rear_));
struct Entry* head_start = rear_;
struct Entry* head_end =
Min(front_, reinterpret_cast<struct Entry*>(p->area_end()));
int entries_count =
static_cast<int>(head_end - head_start) / sizeof(struct Entry);
emergency_stack_ = new List<Entry>(2 * entries_count);
while (head_start != head_end) {
struct Entry* entry = head_start++;
// New space allocation in SemiSpaceCopyObject marked the region
// overlapping with promotion queue as uninitialized.
MSAN_MEMORY_IS_INITIALIZED(entry, sizeof(struct Entry));
emergency_stack_->Add(*entry);
}
rear_ = head_end;
}
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::Scavenge() {
TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_SCAVENGE);
RelocationLock relocation_lock(this);
// 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);
mark_compact_collector()->sweeper().EnsureNewSpaceCompleted();
gc_state_ = SCAVENGE;
// Implements Cheney's copying algorithm
LOG(isolate_, ResourceEvent("scavenge", "begin"));
// Used for updating survived_since_last_expansion_ at function end.
size_t survived_watermark = PromotedSpaceSizeOfObjects();
scavenge_collector_->SelectScavengingVisitorsTable();
if (UsingEmbedderHeapTracer()) {
// Register found wrappers with embedder so it can add them to its marking
// deque and correctly manage the case when v8 scavenger collects the
// wrappers by either keeping wrappables alive, or cleaning marking deque.
RegisterWrappersWithEmbedderHeapTracer();
}
// Flip the semispaces. After flipping, to space is empty, from space has
// live objects.
new_space_->Flip();
new_space_->ResetAllocationInfo();
// We need to sweep newly copied objects which can be either in the
// to space or promoted to the old generation. For to-space
// objects, we treat the bottom of the to space as a queue. Newly
// copied and unswept objects lie between a 'front' mark and the
// allocation pointer.
//
// Promoted objects can go into various old-generation spaces, and
// can be allocated internally in the spaces (from the free list).
// We treat the top of the to space as a queue of addresses of
// promoted objects. The addresses of newly promoted and unswept
// objects lie between a 'front' mark and a 'rear' mark that is
// updated as a side effect of promoting an object.
//
// There is guaranteed to be enough room at the top of the to space
// for the addresses of promoted objects: every object promoted
// frees up its size in bytes from the top of the new space, and
// objects are at least one pointer in size.
Address new_space_front = new_space_->ToSpaceStart();
promotion_queue_.Initialize();
ScavengeVisitor scavenge_visitor(this);
isolate()->global_handles()->IdentifyWeakUnmodifiedObjects(
&IsUnmodifiedHeapObject);
{
// Copy roots.
TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_ROOTS);
IterateRoots(&scavenge_visitor, VISIT_ALL_IN_SCAVENGE);
}
{
// Copy objects reachable from the old generation.
TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_OLD_TO_NEW_POINTERS);
RememberedSet<OLD_TO_NEW>::Iterate(this, [this](Address addr) {
return Scavenger::CheckAndScavengeObject(this, addr);
});
RememberedSet<OLD_TO_NEW>::IterateTyped(
this, [this](SlotType type, Address host_addr, Address addr) {
return UpdateTypedSlotHelper::UpdateTypedSlot(
isolate(), type, addr, [this](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(
this, reinterpret_cast<Address>(addr));
});
});
}
{
TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_WEAK);
// Copy objects reachable from the encountered weak collections list.
scavenge_visitor.VisitPointer(&encountered_weak_collections_);
}
{
// Copy objects reachable from the code flushing candidates list.
TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_CODE_FLUSH_CANDIDATES);
MarkCompactCollector* collector = mark_compact_collector();
if (collector->is_code_flushing_enabled()) {
collector->code_flusher()->IteratePointersToFromSpace(&scavenge_visitor);
}
}
{
TRACE_GC(tracer(), GCTracer::Scope::SCAVENGER_SEMISPACE);
new_space_front = DoScavenge(&scavenge_visitor, new_space_front);
}
isolate()->global_handles()->MarkNewSpaceWeakUnmodifiedObjectsPending(
&IsUnscavengedHeapObject);
isolate()->global_handles()->IterateNewSpaceWeakUnmodifiedRoots(
&scavenge_visitor);
new_space_front = DoScavenge(&scavenge_visitor, new_space_front);
UpdateNewSpaceReferencesInExternalStringTable(
&UpdateNewSpaceReferenceInExternalStringTableEntry);
promotion_queue_.Destroy();
incremental_marking()->UpdateMarkingDequeAfterScavenge();
ScavengeWeakObjectRetainer weak_object_retainer(this);
ProcessYoungWeakReferences(&weak_object_retainer);
DCHECK(new_space_front == new_space_->top());
// Set age mark.
new_space_->set_age_mark(new_space_->top());
ArrayBufferTracker::FreeDeadInNewSpace(this);
// Update how much has survived scavenge.
DCHECK_GE(PromotedSpaceSizeOfObjects(), survived_watermark);
IncrementYoungSurvivorsCounter(PromotedSpaceSizeOfObjects() +
new_space_->Size() - survived_watermark);
LOG(isolate_, ResourceEvent("scavenge", "end"));
gc_state_ = NOT_IN_GC;
}
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.
heap->FinalizeExternalString(String::cast(*p));
return NULL;
}
// String is still reachable.
return String::cast(first_word.ToForwardingAddress());
}
void Heap::UpdateNewSpaceReferencesInExternalStringTable(
ExternalStringTableUpdaterCallback updater_func) {
if (external_string_table_.new_space_strings_.is_empty()) return;
Object** start = &external_string_table_.new_space_strings_[0];
Object** end = start + external_string_table_.new_space_strings_.length();
Object** last = start;
for (Object** p = start; p < end; ++p) {
String* target = updater_func(this, p);
if (target == NULL) continue;
DCHECK(target->IsExternalString());
if (InNewSpace(target)) {
// String is still in new space. Update the table entry.
*last = target;
++last;
} else {
// String got promoted. Move it to the old string list.
external_string_table_.AddOldString(target);
}
}
DCHECK(last <= end);
external_string_table_.ShrinkNewStrings(static_cast<int>(last - start));
}
void Heap::UpdateReferencesInExternalStringTable(
ExternalStringTableUpdaterCallback updater_func) {
// Update old space string references.
if (external_string_table_.old_space_strings_.length() > 0) {
Object** start = &external_string_table_.old_space_strings_[0];
Object** end = start + external_string_table_.old_space_strings_.length();
for (Object** p = start; p < end; ++p) *p = updater_func(this, p);
}
UpdateNewSpaceReferencesInExternalStringTable(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 ObjectVisitor {
public:
explicit ExternalStringTableVisitorAdapter(
v8::ExternalResourceVisitor* visitor)
: visitor_(visitor) {}
virtual void VisitPointers(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_.Iterate(&external_string_table_visitor);
}
Address Heap::DoScavenge(ObjectVisitor* scavenge_visitor,
Address new_space_front) {
do {
SemiSpace::AssertValidRange(new_space_front, new_space_->top());
// The addresses new_space_front and new_space_.top() define a
// queue of unprocessed copied objects. Process them until the
// queue is empty.
while (new_space_front != new_space_->top()) {
if (!Page::IsAlignedToPageSize(new_space_front)) {
HeapObject* object = HeapObject::FromAddress(new_space_front);
new_space_front +=
StaticScavengeVisitor::IterateBody(object->map(), object);
} else {
new_space_front = Page::FromAllocationAreaAddress(new_space_front)
->next_page()
->area_start();
}
}
// Promote and process all the to-be-promoted objects.
{
while (!promotion_queue()->is_empty()) {
HeapObject* target;
int32_t size;
bool was_marked_black;
promotion_queue()->remove(&target, &size, &was_marked_black);
// Promoted object might be already partially visited
// during old space pointer iteration. Thus we search specifically
// for pointers to from semispace instead of looking for pointers
// to new space.
DCHECK(!target->IsMap());
IterateAndScavengePromotedObject(target, static_cast<int>(size),
was_marked_black);
}
}
// Take another spin if there are now unswept objects in new space
// (there are currently no more unswept promoted objects).
} while (new_space_front != new_space_->top());
return new_space_front;
}
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;
case kSimd128Unaligned:
return kSimd128Size - 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.
if (alignment == kSimd128Unaligned) {
return (kSimd128Size - (static_cast<int>(offset) + kPointerSize)) &
kSimd128AlignmentMask;
}
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(filler_size > 0);
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;
}
HeapObject* Heap::DoubleAlignForDeserialization(HeapObject* object, int size) {
return AlignWithFiller(object, size - kPointerSize, size, kDoubleAligned);
}
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.
reinterpret_cast<Map*>(result)->set_map(
reinterpret_cast<Map*>(root(kMetaMapRootIndex)));
reinterpret_cast<Map*>(result)->set_instance_type(instance_type);
reinterpret_cast<Map*>(result)->set_instance_size(instance_size);
// Initialize to only containing tagged fields.
reinterpret_cast<Map*>(result)->set_visitor_id(
StaticVisitorBase::GetVisitorId(instance_type, instance_size, false));
if (FLAG_unbox_double_fields) {
reinterpret_cast<Map*>(result)
->set_layout_descriptor(LayoutDescriptor::FastPointerLayout());
}
reinterpret_cast<Map*>(result)->clear_unused();
reinterpret_cast<Map*>(result)
->set_inobject_properties_or_constructor_function_index(0);
reinterpret_cast<Map*>(result)->set_unused_property_fields(0);
reinterpret_cast<Map*>(result)->set_bit_field(0);
reinterpret_cast<Map*>(result)->set_bit_field2(0);
int bit_field3 = Map::EnumLengthBits::encode(kInvalidEnumCacheSentinel) |
Map::OwnsDescriptors::encode(true) |
Map::ConstructionCounter::encode(Map::kNoSlackTracking);
reinterpret_cast<Map*>(result)->set_bit_field3(bit_field3);
reinterpret_cast<Map*>(result)->set_weak_cell_cache(Smi::kZero);
return result;
}
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_no_write_barrier(meta_map());
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_code_cache(empty_fixed_array(), SKIP_WRITE_BARRIER);
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(Heap::GetStaticVisitorIdForMap(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,
ClearBlackArea::kNo);
return obj;
}
const Heap::StringTypeTable Heap::string_type_table[] = {
#define STRING_TYPE_ELEMENT(type, size, name, camel_name) \
{ type, size, k##camel_name##MapRootIndex } \
,
STRING_TYPE_LIST(STRING_TYPE_ELEMENT)
#undef STRING_TYPE_ELEMENT
};
const Heap::ConstantStringTable Heap::constant_string_table[] = {
{"", kempty_stringRootIndex},
#define CONSTANT_STRING_ELEMENT(name, contents) \
{ contents, k##name##RootIndex } \
,
INTERNALIZED_STRING_LIST(CONSTANT_STRING_ELEMENT)
#undef CONSTANT_STRING_ELEMENT
};
const Heap::StructTable Heap::struct_table[] = {
#define STRUCT_TABLE_ELEMENT(NAME, Name, name) \
{ NAME##_TYPE, Name::kSize, k##Name##MapRootIndex } \
,
STRUCT_LIST(STRUCT_TABLE_ELEMENT)
#undef STRUCT_TABLE_ELEMENT
};
namespace {
void FinalizePartialMap(Heap* heap, Map* map) {
map->set_code_cache(heap->empty_fixed_array());
map->set_dependent_code(DependentCode::cast(heap->empty_fixed_array()));
map->set_raw_transitions(Smi::kZero);
map->set_instance_descriptors(heap->empty_descriptor_array());
if (FLAG_unbox_double_fields) {
map->set_layout_descriptor(LayoutDescriptor::FastPointerLayout());
}
map->set_prototype(heap->null_value());
map->set_constructor_or_backpointer(heap->null_value());
}
} // namespace
bool Heap::CreateInitialMaps() {
HeapObject* obj = nullptr;
{
AllocationResult allocation = AllocatePartialMap(MAP_TYPE, Map::kSize);
if (!allocation.To(&obj)) return false;
}
// Map::cast cannot be used due to uninitialized map field.
Map* new_meta_map = reinterpret_cast<Map*>(obj);
set_meta_map(new_meta_map);
new_meta_map->set_map(new_meta_map);
{ // Partial map allocation
#define ALLOCATE_PARTIAL_MAP(instance_type, size, field_name) \
{ \
Map* map; \
if (!AllocatePartialMap((instance_type), (size)).To(&map)) return false; \
set_##field_name##_map(map); \
}
ALLOCATE_PARTIAL_MAP(FIXED_ARRAY_TYPE, kVariableSizeSentinel, fixed_array);
fixed_array_map()->set_elements_kind(FAST_HOLEY_ELEMENTS);
ALLOCATE_PARTIAL_MAP(ODDBALL_TYPE, Oddball::kSize, undefined);
ALLOCATE_PARTIAL_MAP(ODDBALL_TYPE, Oddball::kSize, null);
ALLOCATE_PARTIAL_MAP(ODDBALL_TYPE, Oddball::kSize, the_hole);
#undef ALLOCATE_PARTIAL_MAP
}
// Allocate the empty array.
{
AllocationResult allocation = AllocateEmptyFixedArray();
if (!allocation.To(&obj)) return false;
}
set_empty_fixed_array(FixedArray::cast(obj));
{
AllocationResult allocation = Allocate(null_map(), OLD_SPACE);
if (!allocation.To(&obj)) return false;
}
set_null_value(Oddball::cast(obj));
Oddball::cast(obj)->set_kind(Oddball::kNull);
{
AllocationResult allocation = Allocate(undefined_map(), OLD_SPACE);
if (!allocation.To(&obj)) return false;
}
set_undefined_value(Oddball::cast(obj));
Oddball::cast(obj)->set_kind(Oddball::kUndefined);
DCHECK(!InNewSpace(undefined_value()));
{
AllocationResult allocation = Allocate(the_hole_map(), OLD_SPACE);
if (!allocation.To(&obj)) return false;
}
set_the_hole_value(Oddball::cast(obj));
Oddball::cast(obj)->set_kind(Oddball::kTheHole);
// Set preliminary exception sentinel value before actually initializing it.
set_exception(null_value());
// Allocate the empty descriptor array.
{
AllocationResult allocation = AllocateEmptyFixedArray();
if (!allocation.To(&obj)) return false;
}
set_empty_descriptor_array(DescriptorArray::cast(obj));
// Fix the instance_descriptors for the existing maps.
FinalizePartialMap(this, meta_map());
FinalizePartialMap(this, fixed_array_map());
FinalizePartialMap(this, undefined_map());
undefined_map()->set_is_undetectable();
FinalizePartialMap(this, null_map());
null_map()->set_is_undetectable();
FinalizePartialMap(this, the_hole_map());
{ // Map allocation
#define ALLOCATE_MAP(instance_type, size, field_name) \
{ \
Map* map; \
if (!AllocateMap((instance_type), size).To(&map)) return false; \
set_##field_name##_map(map); \
}
#define ALLOCATE_VARSIZE_MAP(instance_type, field_name) \
ALLOCATE_MAP(instance_type, kVariableSizeSentinel, field_name)
#define ALLOCATE_PRIMITIVE_MAP(instance_type, size, field_name, \
constructor_function_index) \
{ \
ALLOCATE_MAP((instance_type), (size), field_name); \
field_name##_map()->SetConstructorFunctionIndex( \
(constructor_function_index)); \
}
ALLOCATE_VARSIZE_MAP(FIXED_ARRAY_TYPE, fixed_cow_array)
fixed_cow_array_map()->set_elements_kind(FAST_HOLEY_ELEMENTS);
DCHECK_NE(fixed_array_map(), fixed_cow_array_map());
ALLOCATE_VARSIZE_MAP(FIXED_ARRAY_TYPE, scope_info)
ALLOCATE_VARSIZE_MAP(FIXED_ARRAY_TYPE, module_info)
ALLOCATE_PRIMITIVE_MAP(HEAP_NUMBER_TYPE, HeapNumber::kSize, heap_number,
Context::NUMBER_FUNCTION_INDEX)
ALLOCATE_MAP(MUTABLE_HEAP_NUMBER_TYPE, HeapNumber::kSize,
mutable_heap_number)
ALLOCATE_PRIMITIVE_MAP(SYMBOL_TYPE, Symbol::kSize, symbol,
Context::SYMBOL_FUNCTION_INDEX)
#define ALLOCATE_SIMD128_MAP(TYPE, Type, type, lane_count, lane_type) \
ALLOCATE_PRIMITIVE_MAP(SIMD128_VALUE_TYPE, Type::kSize, type, \
Context::TYPE##_FUNCTION_INDEX)
SIMD128_TYPES(ALLOCATE_SIMD128_MAP)
#undef ALLOCATE_SIMD128_MAP
ALLOCATE_MAP(FOREIGN_TYPE, Foreign::kSize, foreign)
ALLOCATE_PRIMITIVE_MAP(ODDBALL_TYPE, Oddball::kSize, boolean,
Context::BOOLEAN_FUNCTION_INDEX);
ALLOCATE_MAP(ODDBALL_TYPE, Oddball::kSize, uninitialized);
ALLOCATE_MAP(ODDBALL_TYPE, Oddball::kSize, arguments_marker);
ALLOCATE_MAP(ODDBALL_TYPE, Oddball::kSize, no_interceptor_result_sentinel);
ALLOCATE_MAP(ODDBALL_TYPE, Oddball::kSize, exception);
ALLOCATE_MAP(ODDBALL_TYPE, Oddball::kSize, termination_exception);
ALLOCATE_MAP(ODDBALL_TYPE, Oddball::kSize, optimized_out);
ALLOCATE_MAP(ODDBALL_TYPE, Oddball::kSize, stale_register);
for (unsigned i = 0; i < arraysize(string_type_table); i++) {
const StringTypeTable& entry = string_type_table[i];
{
AllocationResult allocation = AllocateMap(entry.type, entry.size);
if (!allocation.To(&obj)) return false;
}
Map* map = Map::cast(obj);
map->SetConstructorFunctionIndex(Context::STRING_FUNCTION_INDEX);
// Mark cons string maps as unstable, because their objects can change
// maps during GC.
if (StringShape(entry.type).IsCons()) map->mark_unstable();
roots_[entry.index] = map;
}
{ // Create a separate external one byte string map for native sources.
AllocationResult allocation =
AllocateMap(SHORT_EXTERNAL_ONE_BYTE_STRING_TYPE,
ExternalOneByteString::kShortSize);
if (!allocation.To(&obj)) return false;
Map* map = Map::cast(obj);
map->SetConstructorFunctionIndex(Context::STRING_FUNCTION_INDEX);
set_native_source_string_map(map);
}
ALLOCATE_VARSIZE_MAP(FIXED_DOUBLE_ARRAY_TYPE, fixed_double_array)
fixed_double_array_map()->set_elements_kind(FAST_HOLEY_DOUBLE_ELEMENTS);
ALLOCATE_VARSIZE_MAP(BYTE_ARRAY_TYPE, byte_array)
ALLOCATE_VARSIZE_MAP(BYTECODE_ARRAY_TYPE, bytecode_array)
ALLOCATE_VARSIZE_MAP(FREE_SPACE_TYPE, free_space)
#define ALLOCATE_FIXED_TYPED_ARRAY_MAP(Type, type, TYPE, ctype, size) \
ALLOCATE_VARSIZE_MAP(FIXED_##TYPE##_ARRAY_TYPE, fixed_##type##_array)
TYPED_ARRAYS(ALLOCATE_FIXED_TYPED_ARRAY_MAP)
#undef ALLOCATE_FIXED_TYPED_ARRAY_MAP
ALLOCATE_VARSIZE_MAP(FIXED_ARRAY_TYPE, sloppy_arguments_elements)
ALLOCATE_VARSIZE_MAP(CODE_TYPE, code)
ALLOCATE_MAP(CELL_TYPE, Cell::kSize, cell)
ALLOCATE_MAP(PROPERTY_CELL_TYPE, PropertyCell::kSize, global_property_cell)
ALLOCATE_MAP(WEAK_CELL_TYPE, WeakCell::kSize, weak_cell)
ALLOCATE_MAP(FILLER_TYPE, kPointerSize, one_pointer_filler)
ALLOCATE_MAP(FILLER_TYPE, 2 * kPointerSize, two_pointer_filler)
ALLOCATE_VARSIZE_MAP(TRANSITION_ARRAY_TYPE, transition_array)
for (unsigned i = 0; i < arraysize(struct_table); i++) {
const StructTable& entry = struct_table[i];
Map* map;
if (!AllocateMap(entry.type, entry.size).To(&map)) return false;
roots_[entry.index] = map;
}
ALLOCATE_VARSIZE_MAP(FIXED_ARRAY_TYPE, hash_table)
ALLOCATE_VARSIZE_MAP(FIXED_ARRAY_TYPE, ordered_hash_table)
ALLOCATE_VARSIZE_MAP(FIXED_ARRAY_TYPE, unseeded_number_dictionary)
ALLOCATE_VARSIZE_MAP(FIXED_ARRAY_TYPE, function_context)
ALLOCATE_VARSIZE_MAP(FIXED_ARRAY_TYPE, catch_context)
ALLOCATE_VARSIZE_MAP(FIXED_ARRAY_TYPE, with_context)
ALLOCATE_VARSIZE_MAP(FIXED_ARRAY_TYPE, debug_evaluate_context)
ALLOCATE_VARSIZE_MAP(FIXED_ARRAY_TYPE, block_context)
ALLOCATE_VARSIZE_MAP(FIXED_ARRAY_TYPE, module_context)
ALLOCATE_VARSIZE_MAP(FIXED_ARRAY_TYPE, script_context)
ALLOCATE_VARSIZE_MAP(FIXED_ARRAY_TYPE, script_context_table)
ALLOCATE_VARSIZE_MAP(FIXED_ARRAY_TYPE, native_context)
native_context_map()->set_dictionary_map(true);
native_context_map()->set_visitor_id(
StaticVisitorBase::kVisitNativeContext);
ALLOCATE_MAP(SHARED_FUNCTION_INFO_TYPE, SharedFunctionInfo::kAlignedSize,
shared_function_info)
ALLOCATE_MAP(JS_MESSAGE_OBJECT_TYPE, JSMessageObject::kSize, message_object)
ALLOCATE_MAP(JS_OBJECT_TYPE, JSObject::kHeaderSize + kPointerSize, external)
external_map()->set_is_extensible(false);
#undef ALLOCATE_PRIMITIVE_MAP
#undef ALLOCATE_VARSIZE_MAP
#undef ALLOCATE_MAP
}
{
AllocationResult allocation = AllocateEmptyScopeInfo();
if (!allocation.To(&obj)) return false;
}
set_empty_scope_info(ScopeInfo::cast(obj));
{
AllocationResult allocation = Allocate(boolean_map(), OLD_SPACE);
if (!allocation.To(&obj)) return false;
}
set_true_value(Oddball::cast(obj));
Oddball::cast(obj)->set_kind(Oddball::kTrue);
{
AllocationResult allocation = Allocate(boolean_map(), OLD_SPACE);
if (!allocation.To(&obj)) return false;
}
set_false_value(Oddball::cast(obj));
Oddball::cast(obj)->set_kind(Oddball::kFalse);
{ // Empty arrays
{
ByteArray* byte_array;
if (!AllocateByteArray(0, TENURED).To(&byte_array)) return false;
set_empty_byte_array(byte_array);
}
#define ALLOCATE_EMPTY_FIXED_TYPED_ARRAY(Type, type, TYPE, ctype, size) \
{ \
FixedTypedArrayBase* obj; \
if (!AllocateEmptyFixedTypedArray(kExternal##Type##Array).To(&obj)) \
return false; \
set_empty_fixed_##type##_array(obj); \
}
TYPED_ARRAYS(ALLOCATE_EMPTY_FIXED_TYPED_ARRAY)
#undef ALLOCATE_EMPTY_FIXED_TYPED_ARRAY
}
DCHECK(!InNewSpace(empty_fixed_array()));
return true;
}
AllocationResult Heap::AllocateHeapNumber(double value, 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_no_write_barrier(map);
HeapNumber::cast(result)->set_value(value);
return result;
}
#define SIMD_ALLOCATE_DEFINITION(TYPE, Type, type, lane_count, lane_type) \
AllocationResult Heap::Allocate##Type(lane_type lanes[lane_count], \
PretenureFlag pretenure) { \
int size = Type::kSize; \
STATIC_ASSERT(Type::kSize <= kMaxRegularHeapObjectSize); \
\
AllocationSpace space = SelectSpace(pretenure); \
\
HeapObject* result = nullptr; \
{ \
AllocationResult allocation = \
AllocateRaw(size, space, kSimd128Unaligned); \
if (!allocation.To(&result)) return allocation; \
} \
\
result->set_map_no_write_barrier(type##_map()); \
Type* instance = Type::cast(result); \
for (int i = 0; i < lane_count; i++) { \
instance->set_lane(i, lanes[i]); \
} \
return result; \
}
SIMD128_TYPES(SIMD_ALLOCATE_DEFINITION)
#undef SIMD_ALLOCATE_DEFINITION
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_no_write_barrier(cell_map());
Cell::cast(result)->set_value(value);
return result;
}
AllocationResult Heap::AllocatePropertyCell() {
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_no_write_barrier(global_property_cell_map());
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_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_no_write_barrier(weak_cell_map());
WeakCell::cast(result)->initialize(value);
WeakCell::cast(result)->clear_next(the_hole_value());
return result;
}
AllocationResult Heap::AllocateTransitionArray(int capacity) {
DCHECK(capacity > 0);
HeapObject* raw_array = nullptr;
{
AllocationResult allocation = AllocateRawFixedArray(capacity, TENURED);
if (!allocation.To(&raw_array)) return allocation;
}
raw_array->set_map_no_write_barrier(transition_array_map());
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()) {
array->set_next_link(encountered_transition_arrays(),
UPDATE_WEAK_WRITE_BARRIER);
set_encountered_transition_arrays(array);
} else {
array->set_next_link(undefined_value(), SKIP_WRITE_BARRIER);
}
return array;
}
void Heap::CreateApiObjects() {
HandleScope scope(isolate());
set_message_listeners(*TemplateList::New(isolate(), 2));
}
void Heap::CreateJSEntryStub() {
JSEntryStub stub(isolate(), StackFrame::ENTRY);
set_js_entry_code(*stub.GetCode());
}
void Heap::CreateJSConstructEntryStub() {
JSEntryStub stub(isolate(), StackFrame::ENTRY_CONSTRUCT);
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());
// 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();
}
void Heap::CreateInitialObjects() {
HandleScope scope(isolate());
Factory* factory = isolate()->factory();
// The -0 value must be set before NewNumber works.
set_minus_zero_value(*factory->NewHeapNumber(-0.0, IMMUTABLE, TENURED));
DCHECK(std::signbit(minus_zero_value()->Number()) != 0);
set_nan_value(*factory->NewHeapNumber(
std::numeric_limits<double>::quiet_NaN(), IMMUTABLE, TENURED));
set_hole_nan_value(*factory->NewHeapNumber(bit_cast<double>(kHoleNanInt64),
IMMUTABLE, TENURED));
set_infinity_value(*factory->NewHeapNumber(V8_INFINITY, IMMUTABLE, TENURED));
set_minus_infinity_value(
*factory->NewHeapNumber(-V8_INFINITY, IMMUTABLE, TENURED));
// Allocate initial string table.
set_string_table(*StringTable::New(isolate(), kInitialStringTableSize));
// Allocate
// Finish initializing oddballs after creating the string table.
Oddball::Initialize(isolate(), factory->undefined_value(), "undefined",
factory->nan_value(), "undefined", Oddball::kUndefined);
// Initialize the null_value.
Oddball::Initialize(isolate(), factory->null_value(), "null",
handle(Smi::kZero, isolate()), "object", Oddball::kNull);
// Initialize the_hole_value.
Oddball::Initialize(isolate(), factory->the_hole_value(), "hole",
factory->hole_nan_value(), "undefined",
Oddball::kTheHole);
// Initialize the true_value.
Oddball::Initialize(isolate(), factory->true_value(), "true",
handle(Smi::FromInt(1), isolate()), "boolean",
Oddball::kTrue);
// Initialize the false_value.
Oddball::Initialize(isolate(), factory->false_value(), "false",
handle(Smi::kZero, isolate()), "boolean",
Oddball::kFalse);
set_uninitialized_value(
*factory->NewOddball(factory->uninitialized_map(), "uninitialized",
handle(Smi::FromInt(-1), isolate()), "undefined",
Oddball::kUninitialized));
set_arguments_marker(
*factory->NewOddball(factory->arguments_marker_map(), "arguments_marker",
handle(Smi::FromInt(-4), isolate()), "undefined",
Oddball::kArgumentsMarker));
set_no_interceptor_result_sentinel(*factory->NewOddball(
factory->no_interceptor_result_sentinel_map(),
"no_interceptor_result_sentinel", handle(Smi::FromInt(-2), isolate()),
"undefined", Oddball::kOther));
set_termination_exception(*factory->NewOddball(
factory->termination_exception_map(), "termination_exception",
handle(Smi::FromInt(-3), isolate()), "undefined", Oddball::kOther));
set_exception(*factory->NewOddball(factory->exception_map(), "exception",
handle(Smi::FromInt(-5), isolate()),
"undefined", Oddball::kException));
set_optimized_out(*factory->NewOddball(factory->optimized_out_map(),
"optimized_out",
handle(Smi::FromInt(-6), isolate()),
"undefined", Oddball::kOptimizedOut));
set_stale_register(
*factory->NewOddball(factory->stale_register_map(), "stale_register",
handle(Smi::FromInt(-7), isolate()), "undefined",
Oddball::kStaleRegister));
for (unsigned i = 0; i < arraysize(constant_string_table); i++) {
Handle<String> str =
factory->InternalizeUtf8String(constant_string_table[i].contents);
roots_[constant_string_table[i].index] = *str;
}
// Create the code_stubs dictionary. The initial size is set to avoid
// expanding the dictionary during bootstrapping.
set_code_stubs(*UnseededNumberDictionary::New(isolate(), 128));
set_instanceof_cache_function(Smi::kZero);
set_instanceof_cache_map(Smi::kZero);
set_instanceof_cache_answer(Smi::kZero);
{
HandleScope scope(isolate());
#define SYMBOL_INIT(name) \
{ \
Handle<String> name##d = factory->NewStringFromStaticChars(#name); \
Handle<Symbol> symbol(isolate()->factory()->NewPrivateSymbol()); \
symbol->set_name(*name##d); \
roots_[k##name##RootIndex] = *symbol; \
}
PRIVATE_SYMBOL_LIST(SYMBOL_INIT)
#undef SYMBOL_INIT
}
{
HandleScope scope(isolate());
#define SYMBOL_INIT(name, description) \
Handle<Symbol> name = factory->NewSymbol(); \
Handle<String> name##d = factory->NewStringFromStaticChars(#description); \
name->set_name(*name##d); \
roots_[k##name##RootIndex] = *name;
PUBLIC_SYMBOL_LIST(SYMBOL_INIT)
#undef SYMBOL_INIT
#define SYMBOL_INIT(name, description) \
Handle<Symbol> name = factory->NewSymbol(); \
Handle<String> name##d = factory->NewStringFromStaticChars(#description); \
name->set_is_well_known_symbol(true); \
name->set_name(*name##d); \
roots_[k##name##RootIndex] = *name;
WELL_KNOWN_SYMBOL_LIST(SYMBOL_INIT)
#undef SYMBOL_INIT
}
Handle<NameDictionary> empty_properties_dictionary =
NameDictionary::New(isolate(), 0, TENURED);
empty_properties_dictionary->SetRequiresCopyOnCapacityChange();
set_empty_properties_dictionary(*empty_properties_dictionary);
set_number_string_cache(
*factory->NewFixedArray(kInitialNumberStringCacheSize * 2, TENURED));
// Allocate cache for single character one byte strings.
set_single_character_string_cache(
*factory->NewFixedArray(String::kMaxOneByteCharCode + 1, TENURED));
// Allocate cache for string split and regexp-multiple.
set_string_split_cache(*factory->NewFixedArray(
RegExpResultsCache::kRegExpResultsCacheSize, TENURED));
set_regexp_multiple_cache(*factory->NewFixedArray(
RegExpResultsCache::kRegExpResultsCacheSize, TENURED));
// Allocate cache for external strings pointing to native source code.
set_natives_source_cache(
*factory->NewFixedArray(Natives::GetBuiltinsCount()));
set_experimental_natives_source_cache(
*factory->NewFixedArray(ExperimentalNatives::GetBuiltinsCount()));
set_extra_natives_source_cache(
*factory->NewFixedArray(ExtraNatives::GetBuiltinsCount()));
set_experimental_extra_natives_source_cache(
*factory->NewFixedArray(ExperimentalExtraNatives::GetBuiltinsCount()));
set_undefined_cell(*factory->NewCell(factory->undefined_value()));
// The symbol registry is initialized lazily.
set_symbol_registry(Smi::kZero);
// Microtask queue uses the empty fixed array as a sentinel for "empty".
// Number of queued microtasks stored in Isolate::pending_microtask_count().
set_microtask_queue(empty_fixed_array());
{
StaticFeedbackVectorSpec spec;
FeedbackVectorSlot slot = spec.AddLoadICSlot();
DCHECK_EQ(slot, FeedbackVectorSlot(TypeFeedbackVector::kDummyLoadICSlot));
slot = spec.AddKeyedLoadICSlot();
DCHECK_EQ(slot,
FeedbackVectorSlot(TypeFeedbackVector::kDummyKeyedLoadICSlot));
slot = spec.AddStoreICSlot();
DCHECK_EQ(slot, FeedbackVectorSlot(TypeFeedbackVector::kDummyStoreICSlot));
slot = spec.AddKeyedStoreICSlot();
DCHECK_EQ(slot,
FeedbackVectorSlot(TypeFeedbackVector::kDummyKeyedStoreICSlot));
Handle<TypeFeedbackMetadata> dummy_metadata =
TypeFeedbackMetadata::New(isolate(), &spec);
Handle<TypeFeedbackVector> dummy_vector =
TypeFeedbackVector::New(isolate(), dummy_metadata);
set_dummy_vector(*dummy_vector);
// Now initialize dummy vector's entries.
LoadICNexus(isolate()).ConfigureMegamorphic();
StoreICNexus(isolate()).ConfigureMegamorphic();
KeyedLoadICNexus(isolate()).ConfigureMegamorphicKeyed(PROPERTY);
KeyedStoreICNexus(isolate()).ConfigureMegamorphicKeyed(PROPERTY);
}
{
// Create a canonical empty TypeFeedbackVector, which is shared by all
// functions that don't need actual type feedback slots. Note however
// that all these functions will share the same invocation count, but
// that shouldn't matter since we only use the invocation count to
// relativize the absolute call counts, but we can only have call counts
// if we have actual feedback slots.
Handle<FixedArray> empty_type_feedback_vector = factory->NewFixedArray(
TypeFeedbackVector::kReservedIndexCount, TENURED);
empty_type_feedback_vector->set(TypeFeedbackVector::kMetadataIndex,
empty_fixed_array());
empty_type_feedback_vector->set(TypeFeedbackVector::kInvocationCountIndex,
Smi::kZero);
set_empty_type_feedback_vector(*empty_type_feedback_vector);
// We use a canonical empty LiteralsArray for all functions that neither
// have literals nor need a TypeFeedbackVector (besides the invocation
// count special slot).
Handle<FixedArray> empty_literals_array =
factory->NewFixedArray(1, TENURED);
empty_literals_array->set(0, *empty_type_feedback_vector);
set_empty_literals_array(*empty_literals_array);
}
{
Handle<FixedArray> empty_sloppy_arguments_elements =
factory->NewFixedArray(2, TENURED);
empty_sloppy_arguments_elements->set_map(sloppy_arguments_elements_map());
set_empty_sloppy_arguments_elements(*empty_sloppy_arguments_elements);
}
{
Handle<WeakCell> cell = factory->NewWeakCell(factory->undefined_value());
set_empty_weak_cell(*cell);
cell->clear();
}
set_detached_contexts(empty_fixed_array());
set_retained_maps(ArrayList::cast(empty_fixed_array()));
set_weak_object_to_code_table(
*WeakHashTable::New(isolate(), 16, USE_DEFAULT_MINIMUM_CAPACITY,
TENURED));
set_weak_new_space_object_to_code_list(
ArrayList::cast(*(factory->NewFixedArray(16, TENURED))));
weak_new_space_object_to_code_list()->SetLength(0);
set_script_list(Smi::kZero);
Handle<SeededNumberDictionary> slow_element_dictionary =
SeededNumberDictionary::New(isolate(), 0, TENURED);
slow_element_dictionary->set_requires_slow_elements();
set_empty_slow_element_dictionary(*slow_element_dictionary);
set_materialized_objects(*factory->NewFixedArray(0, TENURED));
// Handling of script id generation is in Heap::NextScriptId().
set_last_script_id(Smi::FromInt(v8::UnboundScript::kNoScriptId));
set_next_template_serial_number(Smi::kZero);
// Allocate the empty script.
Handle<Script> script = factory->NewScript(factory->empty_string());
script->set_type(Script::TYPE_NATIVE);
set_empty_script(*script);
Handle<PropertyCell> cell = factory->NewPropertyCell();
cell->set_value(Smi::FromInt(Isolate::kProtectorValid));
set_array_protector(*cell);
cell = factory->NewPropertyCell();
cell->set_value(the_hole_value());
set_empty_property_cell(*cell);
cell = factory->NewPropertyCell();
cell->set_value(Smi::FromInt(Isolate::kProtectorValid));
set_has_instance_protector(*cell);
Handle<Cell> is_concat_spreadable_cell = factory->NewCell(
handle(Smi::FromInt(Isolate::kProtectorValid), isolate()));
set_is_concat_spreadable_protector(*is_concat_spreadable_cell);
Handle<Cell> species_cell = factory->NewCell(
handle(Smi::FromInt(Isolate::kProtectorValid), isolate()));
set_species_protector(*species_cell);
cell = factory->NewPropertyCell();
cell->set_value(Smi::FromInt(Isolate::kProtectorValid));
set_string_length_protector(*cell);
Handle<Cell> fast_array_iteration_cell = factory->NewCell(
handle(Smi::FromInt(Isolate::kProtectorValid), isolate()));
set_fast_array_iteration_protector(*fast_array_iteration_cell);
Handle<Cell> array_iterator_cell = factory->NewCell(
handle(Smi::FromInt(Isolate::kProtectorValid), isolate()));
set_array_iterator_protector(*array_iterator_cell);
set_serialized_templates(empty_fixed_array());
set_weak_stack_trace_list(Smi::kZero);
set_noscript_shared_function_infos(Smi::kZero);
// Initialize context slot cache.
isolate_->context_slot_cache()->Clear();
// Initialize descriptor cache.
isolate_->descriptor_lookup_cache()->Clear();
// Initialize compilation cache.
isolate_->compilation_cache()->Clear();
}
bool Heap::RootCanBeWrittenAfterInitialization(Heap::RootListIndex root_index) {
switch (root_index) {
case kNumberStringCacheRootIndex:
case kInstanceofCacheFunctionRootIndex:
case kInstanceofCacheMapRootIndex:
case kInstanceofCacheAnswerRootIndex:
case kCodeStubsRootIndex:
case kEmptyScriptRootIndex:
case kSymbolRegistryRootIndex:
case kScriptListRootIndex:
case kMaterializedObjectsRootIndex:
case kMicrotaskQueueRootIndex:
case kDetachedContextsRootIndex:
case kWeakObjectToCodeTableRootIndex:
case kWeakNewSpaceObjectToCodeListRootIndex:
case kRetainedMapsRootIndex:
case kNoScriptSharedFunctionInfosRootIndex:
case kWeakStackTraceListRootIndex:
case kSerializedTemplatesRootIndex:
// 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) {
return !RootCanBeWrittenAfterInitialization(root_index) &&
!InNewSpace(root(root_index));
}
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();
return kUndefinedValueRootIndex;
}
}
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();
return kUndefinedValueRootIndex;
}
}
FixedTypedArrayBase* Heap::EmptyFixedTypedArrayForMap(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::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_no_write_barrier(byte_array_map());
ByteArray::cast(result)->set_length(length);
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_no_write_barrier(bytecode_array_map());
BytecodeArray* instance = BytecodeArray::cast(result);
instance->set_length(length);
instance->set_frame_size(frame_size);
instance->set_parameter_count(parameter_count);
instance->set_interrupt_budget(interpreter::Interpreter::InterruptBudget());
instance->set_osr_loop_nesting_level(0);
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);
return result;
}
void Heap::CreateFillerObjectAt(Address addr, int size, ClearRecordedSlots mode,
ClearBlackArea black_area_mode) {
if (size == 0) return;
HeapObject* filler = HeapObject::FromAddress(addr);
if (size == kPointerSize) {
filler->set_map_no_write_barrier(
reinterpret_cast<Map*>(root(kOnePointerFillerMapRootIndex)));
} else if (size == 2 * kPointerSize) {
filler->set_map_no_write_barrier(
reinterpret_cast<Map*>(root(kTwoPointerFillerMapRootIndex)));
} else {
DCHECK_GT(size, 2 * kPointerSize);
filler->set_map_no_write_barrier(
reinterpret_cast<Map*>(root(kFreeSpaceMapRootIndex)));
FreeSpace::cast(filler)->nobarrier_set_size(size);
}
if (mode == ClearRecordedSlots::kYes) {
ClearRecordedSlotRange(addr, addr + size);
}
// If the location where the filler is created is within a black area we have
// to clear the mark bits of the filler space.
if (black_area_mode == ClearBlackArea::kYes &&
incremental_marking()->black_allocation() &&
Marking::IsBlackOrGrey(ObjectMarking::MarkBitFrom(addr))) {
Page* page = Page::FromAddress(addr);
page->markbits()->ClearRange(page->AddressToMarkbitIndex(addr),
page->AddressToMarkbitIndex(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());
}
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();
}
void Heap::AdjustLiveBytes(HeapObject* object, int by, InvocationMode mode) {
// As long as the inspected object is black and we are currently not iterating
// the heap using HeapIterator, we can update the live byte count. We cannot
// update while using HeapIterator because the iterator is temporarily
// marking the whole object graph, without updating live bytes.
if (lo_space()->Contains(object)) {
lo_space()->AdjustLiveBytes(by);
} else if (!in_heap_iterator() &&
!mark_compact_collector()->sweeping_in_progress() &&
Marking::IsBlack(ObjectMarking::MarkBitFrom(object->address()))) {
if (mode == SEQUENTIAL_TO_SWEEPER) {
MemoryChunk::IncrementLiveBytesFromGC(object, by);
} else {
MemoryChunk::IncrementLiveBytesFromMutator(object, by);
}
}
}
FixedArrayBase* Heap::LeftTrimFixedArray(FixedArrayBase* object,
int elements_to_trim) {
CHECK_NOT_NULL(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;
// Transfer the mark bits to their new location if the object is not within
// a black area.
if (!incremental_marking()->black_allocation() ||
!Marking::IsBlack(ObjectMarking::MarkBitFrom(new_start))) {
IncrementalMarking::TransferMark(this, old_start, 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.
DCHECK(CanMoveObjectStart(object));
Object** former_start = HeapObject::RawField(object, 0);
int new_start_index = elements_to_trim * (element_size / kPointerSize);
former_start[new_start_index] = map;
former_start[new_start_index + 1] = Smi::FromInt(len - elements_to_trim);
FixedArrayBase* new_object =
FixedArrayBase::cast(HeapObject::FromAddress(new_start));
// Maintain consistency of live bytes during incremental marking
AdjustLiveBytes(new_object, -bytes_to_trim, Heap::CONCURRENT_TO_SWEEPER);
// 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;
}
// Force instantiation of templatized method.
template void Heap::RightTrimFixedArray<Heap::SEQUENTIAL_TO_SWEEPER>(
FixedArrayBase*, int);
template void Heap::RightTrimFixedArray<Heap::CONCURRENT_TO_SWEEPER>(
FixedArrayBase*, int);
template<Heap::InvocationMode mode>
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 {
const int element_size =
object->IsFixedArray() ? kPointerSize : kDoubleSize;
bytes_to_trim = elements_to_trim * element_size;
}
// 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)) {
CreateFillerObjectAt(new_end, bytes_to_trim, ClearRecordedSlots::kYes);
}
// 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);
// Maintain consistency of live bytes during incremental marking
AdjustLiveBytes(object, -bytes_to_trim, mode);
// 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_no_write_barrier(MapForFixedTypedArray(array_type));
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_no_write_barrier(MapForFixedTypedArray(array_type));
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();
// 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) or in large object space.
if (!code_space_->FirstPage()->Contains(address) &&
MemoryChunk::FromAddress(address)->owner()->identity() != LO_SPACE) {
// 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_no_write_barrier(code_map());
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());
code->set_gc_metadata(Smi::kZero);
code->set_ic_age(global_ic_age_);
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());
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()->IterateBlackObject(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_no_write_barrier(bytecode_array_map());
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_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());
bytecode_array->CopyBytecodesTo(copy);
return copy;
}
void Heap::InitializeAllocationMemento(AllocationMemento* memento,
AllocationSite* allocation_site) {
memento->set_map_no_write_barrier(allocation_memento_map());
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;
// No need for write barrier since object is white and map is in old space.
result->set_map_no_write_barrier(map);
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, FixedArray* properties,
Map* map) {
obj->set_properties(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 internal 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() == 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());
FixedArray* properties = FixedArray::cast(source->properties());
// 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->HasFastDoubleElements()) {
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 (properties->length() > 0) {
FixedArray* prop = nullptr;
{
AllocationResult allocation = CopyFixedArray(properties);
if (!allocation.To(&prop)) return allocation;
}
JSObject::cast(clone)->set_properties(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(c != unibrow::Utf8::kBadChar);
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(stream_length == 0);
DCHECK(len == 0);
}
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(chars >= 0);
// 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_no_write_barrier(map);
// 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(size <= SeqOneByteString::kMaxSize);
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_no_write_barrier(one_byte_string_map());
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(size <= SeqTwoByteString::kMaxSize);
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_no_write_barrier(string_map());
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_no_write_barrier(fixed_array_map());
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_no_write_barrier(scope_info_map());
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_no_write_barrier(fixed_array_map());
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_no_write_barrier(fixed_cow_array_map());
return result;
}
AllocationResult Heap::AllocateEmptyFixedTypedArray(
ExternalArrayType array_type) {
return AllocateFixedTypedArray(0, array_type, false, TENURED);
}
AllocationResult Heap::CopyFixedArrayAndGrow(FixedArray* 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_no_write_barrier(fixed_array_map());
FixedArray* result = FixedArray::cast(obj);
result->set_length(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;
}
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_no_write_barrier(fixed_array_map());
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;
}
AllocationResult Heap::CopyFixedArrayWithMap(FixedArray* 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_no_write_barrier(map);
FixedArray* result = FixedArray::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,
FixedArray::SizeFor(len) - kPointerSize);
return obj;
}
// Slow case: Just copy the content one-by-one.
result->set_length(len);
for (int i = 0; i < len; i++) result->set(i, src->get(i), mode);
return result;
}
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_no_write_barrier(map);
CopyBlock(obj->address() + FixedDoubleArray::kLengthOffset,
src->address() + FixedDoubleArray::kLengthOffset,
FixedDoubleArray::SizeFor(len) - FixedDoubleArray::kLengthOffset);
return obj;
}
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(MemoryChunk::HAS_PROGRESS_BAR);
}
return result;
}
AllocationResult Heap::AllocateFixedArrayWithFiller(int length,
PretenureFlag pretenure,
Object* filler) {
DCHECK(length >= 0);
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_no_write_barrier(fixed_array_map());
FixedArray* array = FixedArray::cast(result);
array->set_length(length);
MemsetPointer(array->data_start(), filler, length);
return array;
}
AllocationResult Heap::AllocateFixedArray(int length, PretenureFlag pretenure) {
return AllocateFixedArrayWithFiller(length, pretenure, undefined_value());
}
AllocationResult Heap::AllocateUninitializedFixedArray(int length) {
if (length == 0) return empty_fixed_array();
HeapObject* obj = nullptr;
{
AllocationResult allocation = AllocateRawFixedArray(length, NOT_TENURED);
if (!allocation.To(&obj)) return allocation;
}
obj->set_map_no_write_barrier(fixed_array_map());
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_no_write_barrier(fixed_double_array_map());
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::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_no_write_barrier(symbol_map());
// 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) {
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();
return exception();
}
int size = map->instance_size();
Struct* result = nullptr;
{
AllocationResult allocation = Allocate(map, OLD_SPACE);
if (!allocation.To(&result)) return allocation;
}
result->InitializeBody(size);
return result;
}
bool Heap::IsHeapIterable() {
// TODO(hpayer): This function is not correct. Allocation folding in old
// space breaks the iterability.
return new_space_top_after_last_gc_ == new_space()->top();
}
void Heap::MakeHeapIterable() {
DCHECK(AllowHeapAllocation::IsAllowed());
if (!IsHeapIterable()) {
CollectAllGarbage(kMakeHeapIterableMask,
GarbageCollectionReason::kMakeHeapIterable);
}
if (mark_compact_collector()->sweeping_in_progress()) {
mark_compact_collector()->EnsureSweepingCompleted();
}
DCHECK(IsHeapIterable());
}
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() || IsLowMemoryDevice();
}
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();
}
}
bool Heap::MarkingDequesAreEmpty() {
return mark_compact_collector()->marking_deque()->IsEmpty() &&
(!UsingEmbedderHeapTracer() ||
(wrappers_to_trace() == 0 &&
embedder_heap_tracer()->NumberOfWrappersToTrace() == 0));
}
void Heap::FinalizeIncrementalMarkingIfComplete(
GarbageCollectionReason gc_reason) {
if (incremental_marking()->IsMarking() &&
(incremental_marking()->IsReadyToOverApproximateWeakClosure() ||
(!incremental_marking()->finalize_marking_completed() &&
MarkingDequesAreEmpty()))) {
FinalizeIncrementalMarking(gc_reason);
} else if (incremental_marking()->IsComplete() || MarkingDequesAreEmpty()) {
CollectAllGarbage(current_gc_flags_, gc_reason);
}
}
bool Heap::TryFinalizeIdleIncrementalMarking(
double idle_time_in_ms, GarbageCollectionReason gc_reason) {
size_t size_of_objects = static_cast<size_t>(SizeOfObjects());
double final_incremental_mark_compact_speed_in_bytes_per_ms =
tracer()->FinalIncrementalMarkCompactSpeedInBytesPerMillisecond();
if (incremental_marking()->IsReadyToOverApproximateWeakClosure() ||
(!incremental_marking()->finalize_marking_completed() &&
MarkingDequesAreEmpty() &&
gc_idle_time_handler_->ShouldDoOverApproximateWeakClosure(
idle_time_in_ms))) {
FinalizeIncrementalMarking(gc_reason);
return true;
} else if (incremental_marking()->IsComplete() ||
(MarkingDequesAreEmpty() &&
gc_idle_time_handler_->ShouldDoFinalIncrementalMarkCompact(
idle_time_in_ms, size_of_objects,
final_incremental_mark_compact_speed_in_bytes_per_ms))) {
CollectAllGarbage(current_gc_flags_, gc_reason);
return true;
}
return false;
}
void Heap::RegisterReservationsForBlackAllocation(Reservation* reservations) {
// TODO(hpayer): We do not have to iterate reservations on black objects
// for marking. We just have to execute the special visiting side effect
// code that adds objects to global data structures, e.g. for array buffers.
// Code space, map space, and large object space do not use black pages.
// Hence we have to color all objects of the reservation first black to avoid
// unnecessary marking deque load.
if (incremental_marking()->black_allocation()) {
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);
Marking::MarkBlack(ObjectMarking::MarkBitFrom(obj));
addr += obj->Size();
}
}
}
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);
incremental_marking()->IterateBlackObject(obj);
addr += obj->Size();
}
}
}
}
}
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) {
TryFinalizeIdleIncrementalMarking(
remaining_idle_time_in_ms,
GarbageCollectionReason::kFinalizeMarkingViaTask);
}
result = incremental_marking()->IsStopped();
break;
}
case DO_FULL_GC: {
DCHECK(contexts_disposed_ > 0);
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;
isolate()->counters()->gc_idle_time_allotted_in_ms()->AddSample(
static_cast<int>(idle_time_in_ms));
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 (deadline_difference >= 0) {
if (action.type != DONE && action.type != DO_NOTHING) {
isolate()->counters()->gc_idle_time_limit_undershot()->AddSample(
static_cast<int>(deadline_difference));
}
} else {
isolate()->counters()->gc_idle_time_limit_overshot()->AddSample(
static_cast<int>(-deadline_difference));
}
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);
}
}
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::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_ %" V8PRIdPTR "\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();
return "";
}
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();
return false;
}
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();
return false;
}
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());
if (mark_compact_collector()->sweeping_in_progress()) {
// 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();
if (FLAG_omit_map_checks_for_leaf_maps) {
mark_compact_collector()->VerifyOmittedMapChecks();
}
}
#endif
void Heap::ZapFromSpace() {
if (!new_space_->IsFromSpaceCommitted()) return;
for (Page* page : NewSpacePageRange(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;
}
}
}
class IterateAndScavengePromotedObjectsVisitor final : public ObjectVisitor {
public:
IterateAndScavengePromotedObjectsVisitor(Heap* heap, HeapObject* target,
bool record_slots)
: heap_(heap), target_(target), record_slots_(record_slots) {}
inline void VisitPointers(Object** start, Object** end) override {
Address slot_address = reinterpret_cast<Address>(start);
Page* page = Page::FromAddress(slot_address);
while (slot_address < reinterpret_cast<Address>(end)) {
Object** slot = reinterpret_cast<Object**>(slot_address);
Object* target = *slot;
if (target->IsHeapObject()) {
if (heap_->InFromSpace(target)) {
Scavenger::ScavengeObject(reinterpret_cast<HeapObject**>(slot),
HeapObject::cast(target));
target = *slot;
if (heap_->InNewSpace(target)) {
SLOW_DCHECK(heap_->InToSpace(target));
SLOW_DCHECK(target->IsHeapObject());
RememberedSet<OLD_TO_NEW>::Insert(page, slot_address);
}
SLOW_DCHECK(!MarkCompactCollector::IsOnEvacuationCandidate(
HeapObject::cast(target)));
} else if (record_slots_ &&
MarkCompactCollector::IsOnEvacuationCandidate(
HeapObject::cast(target))) {
heap_->mark_compact_collector()->RecordSlot(target_, slot, target);
}
}
slot_address += kPointerSize;
}
}
inline void VisitCodeEntry(Address code_entry_slot) override {
// Black allocation requires us to process objects referenced by
// promoted objects.
if (heap_->incremental_marking()->black_allocation()) {
Code* code = Code::cast(Code::GetObjectFromEntryAddress(code_entry_slot));
IncrementalMarking::MarkGrey(heap_, code);
}
}
private:
Heap* heap_;
HeapObject* target_;
bool record_slots_;
};
void Heap::IterateAndScavengePromotedObject(HeapObject* target, int size,
bool was_marked_black) {
// We are not collecting slots on new space objects during mutation
// thus we have to scan for pointers to evacuation candidates when we
// promote objects. But we should not record any slots in non-black
// objects. Grey object's slots would be rescanned.
// White object might not survive until the end of collection
// it would be a violation of the invariant to record it's slots.
bool record_slots = false;
if (incremental_marking()->IsCompacting()) {
MarkBit mark_bit = ObjectMarking::MarkBitFrom(target);
record_slots = Marking::IsBlack(mark_bit);
}
IterateAndScavengePromotedObjectsVisitor visitor(this, target, record_slots);
if (target->IsJSFunction()) {
// JSFunctions reachable through kNextFunctionLinkOffset are weak. Slots for
// this links are recorded during processing of weak lists.
JSFunction::BodyDescriptorWeakCode::IterateBody(target, size, &visitor);
} else {
target->IterateBody(target->map()->instance_type(), size, &visitor);
}
// When black allocations is on, we have to visit not already marked black
// objects (in new space) promoted to black pages to keep their references
// alive.
// TODO(hpayer): Implement a special promotion visitor that incorporates
// regular visiting and IteratePromotedObjectPointers.
if (!was_marked_black) {
if (incremental_marking()->black_allocation()) {
IncrementalMarking::MarkGrey(this, target->map());
incremental_marking()->IterateBlackObject(target);
}
}
}
void Heap::IterateRoots(ObjectVisitor* v, VisitMode mode) {
IterateStrongRoots(v, mode);
IterateWeakRoots(v, mode);
}
void Heap::IterateWeakRoots(ObjectVisitor* v, VisitMode mode) {
v->VisitPointer(reinterpret_cast<Object**>(&roots_[kStringTableRootIndex]));
v->Synchronize(VisitorSynchronization::kStringTable);
if (mode != VISIT_ALL_IN_SCAVENGE && mode != VISIT_ALL_IN_SWEEP_NEWSPACE) {
// Scavenge collections have special processing for this.
external_string_table_.Iterate(v);
}
v->Synchronize(VisitorSynchronization::kExternalStringsTable);
}
void Heap::IterateSmiRoots(ObjectVisitor* v) {
// Acquire execution access since we are going to read stack limit values.
ExecutionAccess access(isolate());
v->VisitPointers(&roots_[kSmiRootsStart], &roots_[kRootListLength]);
v->Synchronize(VisitorSynchronization::kSmiRootList);
}
// We cannot avoid stale handles to left-trimmed objects, but can only make
// sure all handles still needed are updated. Filter out a stale pointer
// and clear the slot to allow post processing of handles (needed because
// the sweeper might actually free the underlying page).
class FixStaleLeftTrimmedHandlesVisitor : public ObjectVisitor {
public:
explicit FixStaleLeftTrimmedHandlesVisitor(Heap* heap) : heap_(heap) {
USE(heap_);
}
void VisitPointer(Object** p) override { FixHandle(p); }
void VisitPointers(Object** start, Object** end) override {
for (Object** p = start; p < end; p++) FixHandle(p);
}
private:
inline void FixHandle(Object** p) {
HeapObject* current = reinterpret_cast<HeapObject*>(*p);
if (!current->IsHeapObject()) return;
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(ObjectVisitor* v, VisitMode mode) {
v->VisitPointers(&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 (mode != VISIT_ALL_IN_SCAVENGE) {
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:
case VISIT_ONLY_STRONG_FOR_SERIALIZATION:
isolate_->global_handles()->IterateStrongRoots(v);
break;
case VISIT_ALL_IN_SCAVENGE:
isolate_->global_handles()->IterateNewSpaceStrongAndDependentRoots(v);
break;
case VISIT_ALL_IN_SWEEP_NEWSPACE:
case VISIT_ALL:
isolate_->global_handles()->IterateAllRoots(v);
break;
}
v->Synchronize(VisitorSynchronization::kGlobalHandles);
// Iterate over eternal handles.
if (mode == VISIT_ALL_IN_SCAVENGE) {
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->VisitPointers(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, size_t max_old_space_size,
size_t max_executable_size, size_t code_range_size) {
if (HasBeenSetUp()) return false;
// Overwrite default configuration.
if (max_semi_space_size != 0) {
max_semi_space_size_ = max_semi_space_size * MB;
}
if (max_old_space_size != 0) {
max_old_generation_size_ = max_old_space_size * MB;
}
if (max_executable_size != 0) {
max_executable_size_ = max_executable_size * 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 (FLAG_max_executable_size > 0) {
max_executable_size_ = static_cast<size_t>(FLAG_max_executable_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);
max_executable_size_ = ROUND_UP(max_executable_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 (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;
max_old_generation_size_ =
Max(static_cast<size_t>(paged_space_count * Page::kPageSize),
max_old_generation_size_);
// The max executable size must be less than or equal to the max old
// generation size.
if (max_executable_size_ > max_old_generation_size_) {
max_executable_size_ = 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 * 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, 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) {
if (gc_speed == 0 || mutator_speed == 0) return kMaxHeapGrowingFactor;
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 * kMaxHeapGrowingFactor) ? a / b : kMaxHeapGrowingFactor;
factor = Min(factor, kMaxHeapGrowingFactor);
factor = Max(factor, kMinHeapGrowingFactor);
return factor;
}
size_t Heap::CalculateOldGenerationAllocationLimit(double factor,
size_t old_gen_size) {
CHECK(factor > 1.0);
CHECK(old_gen_size > 0);
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 factor = HeapGrowingFactor(gc_speed, mutator_speed);
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 (IsMemoryConstrainedDevice()) {
factor = Min(factor, kMaxHeapGrowingFactorMemoryConstrained);
}
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 factor = HeapGrowingFactor(gc_speed, mutator_speed);
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;
}
}
// 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 (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() {
if (!incremental_marking()->CanBeActivated() ||
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;
}
// We are close to the allocation limit.
// Choose between the hard and the soft limits.
if (old_generation_space_available == 0 || ShouldOptimizeForMemoryUsage()) {
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();
}
}
V8_DECLARE_ONCE(initialize_gc_once);
static void InitializeGCOnce() {
Scavenger::Initialize();
StaticScavengeVisitor::Initialize();
MarkCompactCollector::Initialize();
}
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;
}
base::CallOnce(&initialize_gc_once, &InitializeGCOnce);
// Set up memory allocator.
memory_allocator_ = new MemoryAllocator(isolate_);
if (!memory_allocator_->SetUp(MaxReserved(), MaxExecutableSize(),
code_range_size_))
return false;
// Initialize store buffer.
store_buffer_ = new StoreBuffer(this);
// Initialize incremental marking.
incremental_marking_ = new IncrementalMarking(this);
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(hash_seed() == 0);
if (FLAG_randomize_hashes) {
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));
}
}
for (int i = 0; i < static_cast<int>(v8::Isolate::kUseCounterFeatureCount);
i++) {
deferred_counters_[i] = 0;
}
tracer_ = new GCTracer(this);
scavenge_collector_ = new Scavenger(this);
mark_compact_collector_ = new MarkCompactCollector(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();
LOG(isolate_, IntPtrTEvent("heap-capacity", Capacity()));
LOG(isolate_, IntPtrTEvent("heap-available", Available()));
store_buffer()->SetUp();
mark_compact_collector()->SetUp();
idle_scavenge_observer_ = new IdleScavengeObserver(
*this, ScavengeJob::kBytesAllocatedBeforeNextIdleTask);
new_space()->AddAllocationObserver(idle_scavenge_observer_);
return true;
}
bool Heap::CreateHeapObjects() {
// Create initial maps.
if (!CreateInitialMaps()) return false;
CreateApiObjects();
// Create initial objects
CreateInitialObjects();
CHECK_EQ(0u, gc_count_);
set_native_contexts_list(undefined_value());
set_allocation_sites_list(undefined_value());
return true;
}
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::PrintAlloctionsHash() {
uint32_t hash = StringHasher::GetHashCore(raw_allocations_hash_);
PrintF("\n### Allocations = %u, hash = 0x%08x\n", allocations_count(), hash);
}
void Heap::NotifyDeserializationComplete() {
DCHECK_EQ(0, gc_count());
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) {
CHECK(p->NeverEvacuate());
}
#endif // DEBUG
}
deserialization_complete_ = true;
}
void Heap::SetEmbedderHeapTracer(EmbedderHeapTracer* tracer) {
DCHECK_EQ(gc_state_, HeapState::NOT_IN_GC);
embedder_heap_tracer_ = tracer;
}
void Heap::RegisterWrappersWithEmbedderHeapTracer() {
DCHECK(UsingEmbedderHeapTracer());
if (wrappers_to_trace_.empty()) {
return;
}
embedder_heap_tracer()->RegisterV8References(wrappers_to_trace_);
wrappers_to_trace_.clear();
}
void Heap::TracePossibleWrapper(JSObject* js_object) {
DCHECK(js_object->WasConstructedFromApiFunction());
if (js_object->GetInternalFieldCount() >= 2 &&
js_object->GetInternalField(0) &&
js_object->GetInternalField(0) != undefined_value() &&
js_object->GetInternalField(1) != undefined_value()) {
DCHECK(reinterpret_cast<intptr_t>(js_object->GetInternalField(0)) % 2 == 0);
wrappers_to_trace_.push_back(std::pair<void*, void*>(
reinterpret_cast<void*>(js_object->GetInternalField(0)),
reinterpret_cast<void*>(js_object->GetInternalField(1))));
}
}
bool Heap::RequiresImmediateWrapperProcessing() {
const size_t kTooManyWrappers = 16000;
return wrappers_to_trace_.size() > kTooManyWrappers;
}
void Heap::RegisterExternallyReferencedObject(Object** object) {
HeapObject* heap_object = HeapObject::cast(*object);
DCHECK(Contains(heap_object));
if (FLAG_incremental_marking_wrappers && incremental_marking()->IsMarking()) {
IncrementalMarking::MarkGrey(this, heap_object);
} else {
DCHECK(mark_compact_collector()->in_use());
MarkBit mark_bit = ObjectMarking::MarkBitFrom(heap_object);
mark_compact_collector()->MarkObject(heap_object, mark_bit);
}
}
void Heap::TearDown() {
#ifdef VERIFY_HEAP
if (FLAG_verify_heap) {
Verify();
}
#endif
UpdateMaximumCommitted();
if (FLAG_print_max_heap_committed) {
PrintF("\n");
PrintF("maximum_committed_by_heap=%" PRIuS " ", MaximumCommittedMemory());
PrintF("maximum_committed_by_new_space=%" PRIuS " ",
new_space_->MaximumCommittedMemory());
PrintF("maximum_committed_by_old_space=%" PRIuS " ",
old_space_->MaximumCommittedMemory());
PrintF("maximum_committed_by_code_space=%" PRIuS " ",
code_space_->MaximumCommittedMemory());
PrintF("maximum_committed_by_map_space=%" PRIuS " ",
map_space_->MaximumCommittedMemory());
PrintF("maximum_committed_by_lo_space=%" PRIuS " ",
lo_space_->MaximumCommittedMemory());
PrintF("\n\n");
}
if (FLAG_verify_predictable) {
PrintAlloctionsHash();
}
new_space()->RemoveAllocationObserver(idle_scavenge_observer_);
delete idle_scavenge_observer_;
idle_scavenge_observer_ = nullptr;
delete scavenge_collector_;
scavenge_collector_ = nullptr;
if (mark_compact_collector_ != nullptr) {
mark_compact_collector_->TearDown();
delete mark_compact_collector_;
mark_compact_collector_ = nullptr;
}
delete incremental_marking_;
incremental_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 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::GCCallback callback,
GCType gc_type, bool pass_isolate) {
DCHECK(callback != NULL);
GCCallbackPair pair(callback, gc_type, pass_isolate);
DCHECK(!gc_prologue_callbacks_.Contains(pair));
return gc_prologue_callbacks_.Add(pair);
}
void Heap::RemoveGCPrologueCallback(v8::Isolate::GCCallback callback) {
DCHECK(callback != NULL);
for (int i = 0; i < gc_prologue_callbacks_.length(); ++i) {
if (gc_prologue_callbacks_[i].callback == callback) {
gc_prologue_callbacks_.Remove(i);
return;
}
}
UNREACHABLE();
}
void Heap::AddGCEpilogueCallback(v8::Isolate::GCCallback callback,
GCType gc_type, bool pass_isolate) {
DCHECK(callback != NULL);
GCCallbackPair pair(callback, gc_type, pass_isolate);
DCHECK(!gc_epilogue_callbacks_.Contains(pair));
return gc_epilogue_callbacks_.Add(pair);
}
void Heap::RemoveGCEpilogueCallback(v8::Isolate::GCCallback callback) {
DCHECK(callback != NULL);
for (int i = 0; i < gc_epilogue_callbacks_.length(); ++i) {
if (gc_epilogue_callbacks_[i].callback == callback) {
gc_epilogue_callbacks_.Remove(i);
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>();
}
} else if (o->IsScript()) {
CompactWeakFixedArray(Script::cast(o)->shared_function_infos());
}
}
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 ObjectVisitor {
public:
void VisitPointers(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 ObjectVisitor {
public:
CheckHandleCountVisitor() : handle_count_(0) {}
~CheckHandleCountVisitor() override {
CHECK(handle_count_ < HandleScope::kCheckHandleThreshold);
}
void VisitPointers(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) {
if (!InNewSpace(object)) {
Address slot_addr = reinterpret_cast<Address>(slot);
Page* page = Page::FromAddress(slot_addr);
DCHECK_EQ(page->owner()->identity(), OLD_SPACE);
store_buffer()->DeleteEntry(slot_addr);
RememberedSet<OLD_TO_OLD>::Remove(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);
RememberedSet<OLD_TO_OLD>::RemoveRange(page, start, end,
SlotSet::FREE_EMPTY_BUCKETS);
}
}
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() {
heap_->mark_compact_collector()->ClearMarkbits();
}
bool SkipObject(HeapObject* object) {
if (object->IsFiller()) return true;
MarkBit mark_bit = ObjectMarking::MarkBitFrom(object);
return Marking::IsWhite(mark_bit);
}
private:
class MarkingVisitor : public ObjectVisitor {
public:
MarkingVisitor() : marking_stack_(10) {}
void VisitPointers(Object** start, Object** end) override {
for (Object** p = start; p < end; p++) {
if (!(*p)->IsHeapObject()) continue;
HeapObject* obj = HeapObject::cast(*p);
MarkBit mark_bit = ObjectMarking::MarkBitFrom(obj);
if (Marking::IsWhite(mark_bit)) {
Marking::WhiteToBlack(mark_bit);
marking_stack_.Add(obj);
}
}
}
void TransitiveClosure() {
while (!marking_stack_.is_empty()) {
HeapObject* obj = marking_stack_.RemoveLast();
obj->Iterate(this);
}
}
private:
List<HeapObject*> marking_stack_;
};
void MarkReachableObjects() {
MarkingVisitor visitor;
heap_->IterateRoots(&visitor, VISIT_ALL);
visitor.TransitiveClosure();
}
Heap* heap_;
DisallowHeapAllocation no_allocation_;
};
HeapIterator::HeapIterator(Heap* heap,
HeapIterator::HeapObjectsFiltering filtering)
: make_heap_iterable_helper_(heap),
no_heap_allocation_(),
heap_(heap),
filtering_(filtering),
filter_(nullptr),
space_iterator_(nullptr),
object_iterator_(nullptr) {
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(object_iterator_ == nullptr);
}
#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;
}
#ifdef DEBUG
Object* const PathTracer::kAnyGlobalObject = NULL;
class PathTracer::MarkVisitor : public ObjectVisitor {
public:
explicit MarkVisitor(PathTracer* tracer) : tracer_(tracer) {}
void VisitPointers(Object** start, Object** end) override {
// Scan all HeapObject pointers in [start, end)
for (Object** p = start; !tracer_->found() && (p < end); p++) {
if ((*p)->IsHeapObject()) tracer_->MarkRecursively(p, this);
}
}
private:
PathTracer* tracer_;
};
class PathTracer::UnmarkVisitor : public ObjectVisitor {
public:
explicit UnmarkVisitor(PathTracer* tracer) : tracer_(tracer) {}
void VisitPointers(Object** start, Object** end) override {
// Scan all HeapObject pointers in [start, end)
for (Object** p = start; p < end; p++) {
if ((*p)->IsHeapObject()) tracer_->UnmarkRecursively(p, this);
}
}
private:
PathTracer* tracer_;
};
void PathTracer::VisitPointers(Object** start, Object** end) {
bool done = ((what_to_find_ == FIND_FIRST) && found_target_);
// Visit all HeapObject pointers in [start, end)
for (Object** p = start; !done && (p < end); p++) {
if ((*p)->IsHeapObject()) {
TracePathFrom(p);
done = ((what_to_find_ == FIND_FIRST) && found_target_);
}
}
}
void PathTracer::Reset() {
found_target_ = false;
object_stack_.Clear();
}
void PathTracer::TracePathFrom(Object** root) {
DCHECK((search_target_ == kAnyGlobalObject) ||
search_target_->IsHeapObject());
found_target_in_trace_ = false;
Reset();
MarkVisitor mark_visitor(this);
MarkRecursively(root, &mark_visitor);
UnmarkVisitor unmark_visitor(this);
UnmarkRecursively(root, &unmark_visitor);
ProcessResults();
}
static bool SafeIsNativeContext(HeapObject* obj) {
return obj->map() == obj->GetHeap()->root(Heap::kNativeContextMapRootIndex);
}
void PathTracer::MarkRecursively(Object** p, MarkVisitor* mark_visitor) {
if (!(*p)->IsHeapObject()) return;
HeapObject* obj = HeapObject::cast(*p);
MapWord map_word = obj->map_word();
if (!map_word.ToMap()->IsHeapObject()) return; // visited before
if (found_target_in_trace_) return; // stop if target found
object_stack_.Add(obj);
if (((search_target_ == kAnyGlobalObject) && obj->IsJSGlobalObject()) ||
(obj == search_target_)) {
found_target_in_trace_ = true;
found_target_ = true;
return;
}
bool is_native_context = SafeIsNativeContext(obj);
// not visited yet
Map* map = Map::cast(map_word.ToMap());
MapWord marked_map_word =
MapWord::FromRawValue(obj->map_word().ToRawValue() + kMarkTag);
obj->set_map_word(marked_map_word);
// Scan the object body.
if (is_native_context && (visit_mode_ == VISIT_ONLY_STRONG)) {
// This is specialized to scan Context's properly.
Object** start =
reinterpret_cast<Object**>(obj->address() + Context::kHeaderSize);
Object** end =
reinterpret_cast<Object**>(obj->address() + Context::kHeaderSize +
Context::FIRST_WEAK_SLOT * kPointerSize);
mark_visitor->VisitPointers(start, end);
} else {
obj->IterateBody(map->instance_type(), obj->SizeFromMap(map), mark_visitor);
}
// Scan the map after the body because the body is a lot more interesting
// when doing leak detection.
MarkRecursively(reinterpret_cast<Object**>(&map), mark_visitor);
if (!found_target_in_trace_) { // don't pop if found the target
object_stack_.RemoveLast();
}
}
void PathTracer::UnmarkRecursively(Object** p, UnmarkVisitor* unmark_visitor) {
if (!(*p)->IsHeapObject()) return;
HeapObject* obj = HeapObject::cast(*p);
MapWord map_word = obj->map_word();
if (map_word.ToMap()->IsHeapObject()) return; // unmarked already
MapWord unmarked_map_word =
MapWord::FromRawValue(map_word.ToRawValue() - kMarkTag);
obj->set_map_word(unmarked_map_word);
Map* map = Map::cast(unmarked_map_word.ToMap());
UnmarkRecursively(reinterpret_cast<Object**>(&map), unmark_visitor);
obj->IterateBody(map->instance_type(), obj->SizeFromMap(map), unmark_visitor);
}
void PathTracer::ProcessResults() {
if (found_target_) {
OFStream os(stdout);
os << "=====================================\n"
<< "==== Path to object ====\n"
<< "=====================================\n\n";
DCHECK(!object_stack_.is_empty());
for (int i = 0; i < object_stack_.length(); i++) {
if (i > 0) os << "\n |\n |\n V\n\n";
object_stack_[i]->Print(os);
}
os << "=====================================\n";
}
}
// Triggers a depth-first traversal of reachable objects from one
// given root object and finds a path to a specific heap object and
// prints it.
void Heap::TracePathToObjectFrom(Object* target, Object* root) {
PathTracer tracer(target, PathTracer::FIND_ALL, VISIT_ALL);
tracer.VisitPointer(&root);
}
// Triggers a depth-first traversal of reachable objects from roots
// and finds a path to a specific heap object and prints it.
void Heap::TracePathToObject(Object* target) {
PathTracer tracer(target, PathTracer::FIND_ALL, VISIT_ALL);
IterateRoots(&tracer, VISIT_ONLY_STRONG);
}
// Triggers a depth-first traversal of reachable objects from roots
// and finds a path to any global object and prints it. Useful for
// determining the source for leaks of global objects.
void Heap::TracePathToGlobal() {
PathTracer tracer(PathTracer::kAnyGlobalObject, PathTracer::FIND_ALL,
VISIT_ALL);
IterateRoots(&tracer, VISIT_ONLY_STRONG);
}
#endif
void Heap::UpdateTotalGCTime(double duration) {
if (FLAG_trace_gc_verbose) {
total_gc_time_ms_ += duration;
}
}
void Heap::ExternalStringTable::CleanUp() {
int last = 0;
Isolate* isolate = heap_->isolate();
for (int i = 0; i < new_space_strings_.length(); ++i) {
if (new_space_strings_[i]->IsTheHole(isolate)) {
continue;
}
DCHECK(new_space_strings_[i]->IsExternalString());
if (heap_->InNewSpace(new_space_strings_[i])) {
new_space_strings_[last++] = new_space_strings_[i];
} else {
old_space_strings_.Add(new_space_strings_[i]);
}
}
new_space_strings_.Rewind(last);
new_space_strings_.Trim();
last = 0;
for (int i = 0; i < old_space_strings_.length(); ++i) {
if (old_space_strings_[i]->IsTheHole(isolate)) {
continue;
}
DCHECK(old_space_strings_[i]->IsExternalString());
DCHECK(!heap_->InNewSpace(old_space_strings_[i]));
old_space_strings_[last++] = old_space_strings_[i];
}
old_space_strings_.Rewind(last);
old_space_strings_.Trim();
#ifdef VERIFY_HEAP
if (FLAG_verify_heap) {
Verify();
}
#endif
}
void Heap::ExternalStringTable::TearDown() {
for (int i = 0; i < new_space_strings_.length(); ++i) {
heap_->FinalizeExternalString(ExternalString::cast(new_space_strings_[i]));
}
new_space_strings_.Free();
for (int i = 0; i < old_space_strings_.length(); ++i) {
heap_->FinalizeExternalString(ExternalString::cast(old_space_strings_[i]));
}
old_space_strings_.Free();
}
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
#define COMPARE_AND_RETURN_NAME(name) \
case ObjectStats::FIRST_CODE_AGE_SUB_TYPE + Code::k##name##CodeAge - \
Code::kFirstCodeAge: \
*object_type = "CODE_TYPE"; \
*object_sub_type = "CODE_AGE/" #name; \
return true;
CODE_AGE_LIST_COMPLETE(COMPARE_AND_RETURN_NAME)
#undef COMPARE_AND_RETURN_NAME
}
return false;
}
// static
int Heap::GetStaticVisitorIdForMap(Map* map) {
return StaticVisitorBase::GetVisitorId(map);
}
} // namespace internal
} // namespace v8