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ara-mdk / platform / external / v8 / 0d5e116f6aee03185f237311a943491bb079a768 / . / src / heap.cc
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// Copyright 2010 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "v8.h"
#include "accessors.h"
#include "api.h"
#include "bootstrapper.h"
#include "codegen-inl.h"
#include "compilation-cache.h"
#include "debug.h"
#include "heap-profiler.h"
#include "global-handles.h"
#include "mark-compact.h"
#include "natives.h"
#include "objects-visiting.h"
#include "scanner.h"
#include "scopeinfo.h"
#include "snapshot.h"
#include "v8threads.h"
#if V8_TARGET_ARCH_ARM && !V8_INTERPRETED_REGEXP
#include "regexp-macro-assembler.h"
#include "arm/regexp-macro-assembler-arm.h"
#endif
namespace v8 {
namespace internal {
String* Heap::hidden_symbol_;
Object* Heap::roots_[Heap::kRootListLength];
NewSpace Heap::new_space_;
OldSpace* Heap::old_pointer_space_ = NULL;
OldSpace* Heap::old_data_space_ = NULL;
OldSpace* Heap::code_space_ = NULL;
MapSpace* Heap::map_space_ = NULL;
CellSpace* Heap::cell_space_ = NULL;
LargeObjectSpace* Heap::lo_space_ = NULL;
int Heap::old_gen_promotion_limit_ = kMinimumPromotionLimit;
int Heap::old_gen_allocation_limit_ = kMinimumAllocationLimit;
int Heap::old_gen_exhausted_ = false;
int Heap::amount_of_external_allocated_memory_ = 0;
int Heap::amount_of_external_allocated_memory_at_last_global_gc_ = 0;
// semispace_size_ should be a power of 2 and old_generation_size_ should be
// a multiple of Page::kPageSize.
#if defined(ANDROID)
int Heap::max_semispace_size_ = 2*MB;
int Heap::max_old_generation_size_ = 192*MB;
int Heap::initial_semispace_size_ = 128*KB;
size_t Heap::code_range_size_ = 0;
#elif defined(V8_TARGET_ARCH_X64)
int Heap::max_semispace_size_ = 16*MB;
int Heap::max_old_generation_size_ = 1*GB;
int Heap::initial_semispace_size_ = 1*MB;
size_t Heap::code_range_size_ = 512*MB;
#else
int Heap::max_semispace_size_ = 8*MB;
int Heap::max_old_generation_size_ = 512*MB;
int Heap::initial_semispace_size_ = 512*KB;
size_t Heap::code_range_size_ = 0;
#endif
// The snapshot semispace size will be the default semispace size if
// snapshotting is used and will be the requested semispace size as
// set up by ConfigureHeap otherwise.
int Heap::reserved_semispace_size_ = Heap::max_semispace_size_;
List<Heap::GCPrologueCallbackPair> Heap::gc_prologue_callbacks_;
List<Heap::GCEpilogueCallbackPair> Heap::gc_epilogue_callbacks_;
GCCallback Heap::global_gc_prologue_callback_ = NULL;
GCCallback Heap::global_gc_epilogue_callback_ = NULL;
HeapObjectCallback Heap::gc_safe_size_of_old_object_ = NULL;
// 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.
int Heap::survived_since_last_expansion_ = 0;
int Heap::external_allocation_limit_ = 0;
Heap::HeapState Heap::gc_state_ = NOT_IN_GC;
int Heap::mc_count_ = 0;
int Heap::ms_count_ = 0;
int Heap::gc_count_ = 0;
GCTracer* Heap::tracer_ = NULL;
int Heap::unflattened_strings_length_ = 0;
int Heap::always_allocate_scope_depth_ = 0;
int Heap::linear_allocation_scope_depth_ = 0;
int Heap::contexts_disposed_ = 0;
int Heap::young_survivors_after_last_gc_ = 0;
int Heap::high_survival_rate_period_length_ = 0;
double Heap::survival_rate_ = 0;
Heap::SurvivalRateTrend Heap::previous_survival_rate_trend_ = Heap::STABLE;
Heap::SurvivalRateTrend Heap::survival_rate_trend_ = Heap::STABLE;
#ifdef DEBUG
bool Heap::allocation_allowed_ = true;
int Heap::allocation_timeout_ = 0;
bool Heap::disallow_allocation_failure_ = false;
#endif // DEBUG
int GCTracer::alive_after_last_gc_ = 0;
double GCTracer::last_gc_end_timestamp_ = 0.0;
int GCTracer::max_gc_pause_ = 0;
int GCTracer::max_alive_after_gc_ = 0;
int GCTracer::min_in_mutator_ = kMaxInt;
int Heap::Capacity() {
if (!HasBeenSetup()) return 0;
return new_space_.Capacity() +
old_pointer_space_->Capacity() +
old_data_space_->Capacity() +
code_space_->Capacity() +
map_space_->Capacity() +
cell_space_->Capacity();
}
int Heap::CommittedMemory() {
if (!HasBeenSetup()) return 0;
return new_space_.CommittedMemory() +
old_pointer_space_->CommittedMemory() +
old_data_space_->CommittedMemory() +
code_space_->CommittedMemory() +
map_space_->CommittedMemory() +
cell_space_->CommittedMemory() +
lo_space_->Size();
}
int Heap::Available() {
if (!HasBeenSetup()) return 0;
return new_space_.Available() +
old_pointer_space_->Available() +
old_data_space_->Available() +
code_space_->Available() +
map_space_->Available() +
cell_space_->Available();
}
bool Heap::HasBeenSetup() {
return old_pointer_space_ != NULL &&
old_data_space_ != NULL &&
code_space_ != NULL &&
map_space_ != NULL &&
cell_space_ != NULL &&
lo_space_ != NULL;
}
int Heap::GcSafeSizeOfOldObject(HeapObject* object) {
ASSERT(!Heap::InNewSpace(object)); // Code only works for old objects.
ASSERT(!MarkCompactCollector::are_map_pointers_encoded());
MapWord map_word = object->map_word();
map_word.ClearMark();
map_word.ClearOverflow();
return object->SizeFromMap(map_word.ToMap());
}
int Heap::GcSafeSizeOfOldObjectWithEncodedMap(HeapObject* object) {
ASSERT(!Heap::InNewSpace(object)); // Code only works for old objects.
ASSERT(MarkCompactCollector::are_map_pointers_encoded());
uint32_t marker = Memory::uint32_at(object->address());
if (marker == MarkCompactCollector::kSingleFreeEncoding) {
return kIntSize;
} else if (marker == MarkCompactCollector::kMultiFreeEncoding) {
return Memory::int_at(object->address() + kIntSize);
} else {
MapWord map_word = object->map_word();
Address map_address = map_word.DecodeMapAddress(Heap::map_space());
Map* map = reinterpret_cast<Map*>(HeapObject::FromAddress(map_address));
return object->SizeFromMap(map);
}
}
GarbageCollector Heap::SelectGarbageCollector(AllocationSpace space) {
// Is global GC requested?
if (space != NEW_SPACE || FLAG_gc_global) {
Counters::gc_compactor_caused_by_request.Increment();
return MARK_COMPACTOR;
}
// Is enough data promoted to justify a global GC?
if (OldGenerationPromotionLimitReached()) {
Counters::gc_compactor_caused_by_promoted_data.Increment();
return MARK_COMPACTOR;
}
// Have allocation in OLD and LO failed?
if (old_gen_exhausted_) {
Counters::gc_compactor_caused_by_oldspace_exhaustion.Increment();
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 (MemoryAllocator::MaxAvailable() <= new_space_.Size()) {
Counters::gc_compactor_caused_by_oldspace_exhaustion.Increment();
return MARK_COMPACTOR;
}
// Default
return SCAVENGER;
}
// TODO(1238405): Combine the infrastructure for --heap-stats and
// --log-gc to avoid the complicated preprocessor and flag testing.
#if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
void Heap::ReportStatisticsBeforeGC() {
// Heap::ReportHeapStatistics will also log NewSpace statistics when
// compiled with ENABLE_LOGGING_AND_PROFILING and --log-gc is set. The
// following logic is used to avoid double logging.
#if defined(DEBUG) && defined(ENABLE_LOGGING_AND_PROFILING)
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();
#elif defined(DEBUG)
if (FLAG_heap_stats) {
new_space_.CollectStatistics();
ReportHeapStatistics("Before GC");
new_space_.ClearHistograms();
}
#elif defined(ENABLE_LOGGING_AND_PROFILING)
if (FLAG_log_gc) {
new_space_.CollectStatistics();
new_space_.ReportStatistics();
new_space_.ClearHistograms();
}
#endif
}
#if defined(ENABLE_LOGGING_AND_PROFILING)
void Heap::PrintShortHeapStatistics() {
if (!FLAG_trace_gc_verbose) return;
PrintF("Memory allocator, used: %8d, available: %8d\n",
MemoryAllocator::Size(),
MemoryAllocator::Available());
PrintF("New space, used: %8d, available: %8d\n",
Heap::new_space_.Size(),
new_space_.Available());
PrintF("Old pointers, used: %8d, available: %8d, waste: %8d\n",
old_pointer_space_->Size(),
old_pointer_space_->Available(),
old_pointer_space_->Waste());
PrintF("Old data space, used: %8d, available: %8d, waste: %8d\n",
old_data_space_->Size(),
old_data_space_->Available(),
old_data_space_->Waste());
PrintF("Code space, used: %8d, available: %8d, waste: %8d\n",
code_space_->Size(),
code_space_->Available(),
code_space_->Waste());
PrintF("Map space, used: %8d, available: %8d, waste: %8d\n",
map_space_->Size(),
map_space_->Available(),
map_space_->Waste());
PrintF("Cell space, used: %8d, available: %8d, waste: %8d\n",
cell_space_->Size(),
cell_space_->Available(),
cell_space_->Waste());
PrintF("Large object space, used: %8d, avaialble: %8d\n",
lo_space_->Size(),
lo_space_->Available());
}
#endif
// 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) && defined(ENABLE_LOGGING_AND_PROFILING)
if (FLAG_heap_stats) {
new_space_.CollectStatistics();
ReportHeapStatistics("After GC");
} else if (FLAG_log_gc) {
new_space_.ReportStatistics();
}
#elif defined(DEBUG)
if (FLAG_heap_stats) ReportHeapStatistics("After GC");
#elif defined(ENABLE_LOGGING_AND_PROFILING)
if (FLAG_log_gc) new_space_.ReportStatistics();
#endif
}
#endif // defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
void Heap::GarbageCollectionPrologue() {
TranscendentalCache::Clear();
ClearJSFunctionResultCaches();
gc_count_++;
unflattened_strings_length_ = 0;
#ifdef DEBUG
ASSERT(allocation_allowed_ && gc_state_ == NOT_IN_GC);
allow_allocation(false);
if (FLAG_verify_heap) {
Verify();
}
if (FLAG_gc_verbose) Print();
#endif
#if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
ReportStatisticsBeforeGC();
#endif
}
int Heap::SizeOfObjects() {
int total = 0;
AllSpaces spaces;
for (Space* space = spaces.next(); space != NULL; space = spaces.next()) {
total += space->Size();
}
return total;
}
void Heap::GarbageCollectionEpilogue() {
#ifdef DEBUG
allow_allocation(true);
ZapFromSpace();
if (FLAG_verify_heap) {
Verify();
}
if (FLAG_print_global_handles) GlobalHandles::Print();
if (FLAG_print_handles) PrintHandles();
if (FLAG_gc_verbose) Print();
if (FLAG_code_stats) ReportCodeStatistics("After GC");
#endif
Counters::alive_after_last_gc.Set(SizeOfObjects());
Counters::symbol_table_capacity.Set(symbol_table()->Capacity());
Counters::number_of_symbols.Set(symbol_table()->NumberOfElements());
#if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
ReportStatisticsAfterGC();
#endif
#ifdef ENABLE_DEBUGGER_SUPPORT
Debug::AfterGarbageCollection();
#endif
}
void Heap::CollectAllGarbage(bool force_compaction,
CollectionPolicy collectionPolicy) {
// 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.
MarkCompactCollector::SetForceCompaction(force_compaction);
CollectGarbage(0, OLD_POINTER_SPACE, collectionPolicy);
MarkCompactCollector::SetForceCompaction(false);
}
void Heap::CollectAllAvailableGarbage() {
CompilationCache::Clear();
CollectAllGarbage(true, AGGRESSIVE);
}
bool Heap::CollectGarbage(int requested_size,
AllocationSpace space,
CollectionPolicy collectionPolicy) {
// The VM is in the GC state until exiting this function.
VMState state(GC);
#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
{ GCTracer tracer;
GarbageCollectionPrologue();
// The GC count was incremented in the prologue. Tell the tracer about
// it.
tracer.set_gc_count(gc_count_);
GarbageCollector collector = SelectGarbageCollector(space);
// Tell the tracer which collector we've selected.
tracer.set_collector(collector);
HistogramTimer* rate = (collector == SCAVENGER)
? &Counters::gc_scavenger
: &Counters::gc_compactor;
rate->Start();
PerformGarbageCollection(collector, &tracer, collectionPolicy);
rate->Stop();
GarbageCollectionEpilogue();
}
#ifdef ENABLE_LOGGING_AND_PROFILING
if (FLAG_log_gc) HeapProfiler::WriteSample();
#endif
switch (space) {
case NEW_SPACE:
return new_space_.Available() >= requested_size;
case OLD_POINTER_SPACE:
return old_pointer_space_->Available() >= requested_size;
case OLD_DATA_SPACE:
return old_data_space_->Available() >= requested_size;
case CODE_SPACE:
return code_space_->Available() >= requested_size;
case MAP_SPACE:
return map_space_->Available() >= requested_size;
case CELL_SPACE:
return cell_space_->Available() >= requested_size;
case LO_SPACE:
return lo_space_->Available() >= requested_size;
}
return false;
}
void Heap::PerformScavenge() {
GCTracer tracer;
PerformGarbageCollection(SCAVENGER, &tracer, NORMAL);
}
#ifdef DEBUG
// Helper class for verifying the symbol table.
class SymbolTableVerifier : public ObjectVisitor {
public:
SymbolTableVerifier() { }
void VisitPointers(Object** start, Object** end) {
// Visit all HeapObject pointers in [start, end).
for (Object** p = start; p < end; p++) {
if ((*p)->IsHeapObject()) {
// Check that the symbol is actually a symbol.
ASSERT((*p)->IsNull() || (*p)->IsUndefined() || (*p)->IsSymbol());
}
}
}
};
#endif // DEBUG
static void VerifySymbolTable() {
#ifdef DEBUG
SymbolTableVerifier verifier;
Heap::symbol_table()->IterateElements(&verifier);
#endif // DEBUG
}
void Heap::ReserveSpace(
int new_space_size,
int pointer_space_size,
int data_space_size,
int code_space_size,
int map_space_size,
int cell_space_size,
int large_object_size) {
NewSpace* new_space = Heap::new_space();
PagedSpace* old_pointer_space = Heap::old_pointer_space();
PagedSpace* old_data_space = Heap::old_data_space();
PagedSpace* code_space = Heap::code_space();
PagedSpace* map_space = Heap::map_space();
PagedSpace* cell_space = Heap::cell_space();
LargeObjectSpace* lo_space = Heap::lo_space();
bool gc_performed = true;
while (gc_performed) {
gc_performed = false;
if (!new_space->ReserveSpace(new_space_size)) {
Heap::CollectGarbage(new_space_size, NEW_SPACE);
gc_performed = true;
}
if (!old_pointer_space->ReserveSpace(pointer_space_size)) {
Heap::CollectGarbage(pointer_space_size, OLD_POINTER_SPACE);
gc_performed = true;
}
if (!(old_data_space->ReserveSpace(data_space_size))) {
Heap::CollectGarbage(data_space_size, OLD_DATA_SPACE);
gc_performed = true;
}
if (!(code_space->ReserveSpace(code_space_size))) {
Heap::CollectGarbage(code_space_size, CODE_SPACE);
gc_performed = true;
}
if (!(map_space->ReserveSpace(map_space_size))) {
Heap::CollectGarbage(map_space_size, MAP_SPACE);
gc_performed = true;
}
if (!(cell_space->ReserveSpace(cell_space_size))) {
Heap::CollectGarbage(cell_space_size, CELL_SPACE);
gc_performed = true;
}
// We add a slack-factor of 2 in order to have space for a series of
// large-object allocations that are only just larger than the page size.
large_object_size *= 2;
// The ReserveSpace method on the large object space checks how much
// we can expand the old generation. This includes expansion caused by
// allocation in the other spaces.
large_object_size += cell_space_size + map_space_size + code_space_size +
data_space_size + pointer_space_size;
if (!(lo_space->ReserveSpace(large_object_size))) {
Heap::CollectGarbage(large_object_size, LO_SPACE);
gc_performed = true;
}
}
}
void Heap::EnsureFromSpaceIsCommitted() {
if (new_space_.CommitFromSpaceIfNeeded()) return;
// Committing memory to from space failed.
// Try shrinking and try again.
PagedSpaces spaces;
for (PagedSpace* space = spaces.next();
space != NULL;
space = spaces.next()) {
space->RelinkPageListInChunkOrder(true);
}
Shrink();
if (new_space_.CommitFromSpaceIfNeeded()) return;
// Committing memory to from space failed again.
// Memory is exhausted and we will die.
V8::FatalProcessOutOfMemory("Committing semi space failed.");
}
class ClearThreadJSFunctionResultCachesVisitor: public ThreadVisitor {
virtual void VisitThread(ThreadLocalTop* top) {
Context* context = top->context_;
if (context == NULL) return;
FixedArray* caches =
context->global()->global_context()->jsfunction_result_caches();
int length = caches->length();
for (int i = 0; i < length; i++) {
JSFunctionResultCache::cast(caches->get(i))->Clear();
}
}
};
void Heap::ClearJSFunctionResultCaches() {
if (Bootstrapper::IsActive()) return;
ClearThreadJSFunctionResultCachesVisitor visitor;
ThreadManager::IterateArchivedThreads(&visitor);
}
class ClearThreadNormalizedMapCachesVisitor: public ThreadVisitor {
virtual void VisitThread(ThreadLocalTop* top) {
Context* context = top->context_;
if (context == NULL) return;
context->global()->global_context()->normalized_map_cache()->Clear();
}
};
void Heap::ClearNormalizedMapCaches() {
if (Bootstrapper::IsActive()) return;
ClearThreadNormalizedMapCachesVisitor visitor;
ThreadManager::IterateArchivedThreads(&visitor);
}
#ifdef DEBUG
enum PageWatermarkValidity {
ALL_VALID,
ALL_INVALID
};
static void VerifyPageWatermarkValidity(PagedSpace* space,
PageWatermarkValidity validity) {
PageIterator it(space, PageIterator::PAGES_IN_USE);
bool expected_value = (validity == ALL_VALID);
while (it.has_next()) {
Page* page = it.next();
ASSERT(page->IsWatermarkValid() == expected_value);
}
}
#endif
void Heap::UpdateSurvivalRateTrend(int start_new_space_size) {
double survival_rate =
(static_cast<double>(young_survivors_after_last_gc_) * 100) /
start_new_space_size;
if (survival_rate > kYoungSurvivalRateThreshold) {
high_survival_rate_period_length_++;
} else {
high_survival_rate_period_length_ = 0;
}
double survival_rate_diff = survival_rate_ - survival_rate;
if (survival_rate_diff > kYoungSurvivalRateAllowedDeviation) {
set_survival_rate_trend(DECREASING);
} else if (survival_rate_diff < -kYoungSurvivalRateAllowedDeviation) {
set_survival_rate_trend(INCREASING);
} else {
set_survival_rate_trend(STABLE);
}
survival_rate_ = survival_rate;
}
void Heap::PerformGarbageCollection(GarbageCollector collector,
GCTracer* tracer,
CollectionPolicy collectionPolicy) {
VerifySymbolTable();
if (collector == MARK_COMPACTOR && global_gc_prologue_callback_) {
ASSERT(!allocation_allowed_);
GCTracer::Scope scope(tracer, GCTracer::Scope::EXTERNAL);
global_gc_prologue_callback_();
}
GCType gc_type =
collector == MARK_COMPACTOR ? kGCTypeMarkSweepCompact : kGCTypeScavenge;
for (int i = 0; i < gc_prologue_callbacks_.length(); ++i) {
if (gc_type & gc_prologue_callbacks_[i].gc_type) {
gc_prologue_callbacks_[i].callback(gc_type, kNoGCCallbackFlags);
}
}
EnsureFromSpaceIsCommitted();
int start_new_space_size = Heap::new_space()->Size();
if (collector == MARK_COMPACTOR) {
// Perform mark-sweep with optional compaction.
MarkCompact(tracer);
bool high_survival_rate_during_scavenges = IsHighSurvivalRate() &&
IsStableOrIncreasingSurvivalTrend();
UpdateSurvivalRateTrend(start_new_space_size);
UpdateOldSpaceLimits();
// 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.
if (collectionPolicy == AGGRESSIVE) {
// 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.
const int kMaxNumberOfAttempts = 7;
for (int attempt = 0; attempt < kMaxNumberOfAttempts; attempt++) {
{ DisableAssertNoAllocation allow_allocation;
GCTracer::Scope scope(tracer, GCTracer::Scope::EXTERNAL);
if (!GlobalHandles::PostGarbageCollectionProcessing()) break;
}
MarkCompact(tracer);
// Weak handle callbacks can allocate data, so keep limits correct.
UpdateOldSpaceLimits();
}
} else {
if (high_survival_rate_during_scavenges &&
IsStableOrIncreasingSurvivalTrend()) {
// Stable high survival rates of young objects both during partial and
// full collection indicate that mutator is either building or modifying
// a structure with a long lifetime.
// In this case we aggressively raise old generation memory limits to
// postpone subsequent mark-sweep collection and thus trade memory
// space for the mutation speed.
old_gen_promotion_limit_ *= 2;
old_gen_allocation_limit_ *= 2;
}
}
{ DisableAssertNoAllocation allow_allocation;
GCTracer::Scope scope(tracer, GCTracer::Scope::EXTERNAL);
GlobalHandles::PostGarbageCollectionProcessing();
}
} else {
tracer_ = tracer;
Scavenge();
tracer_ = NULL;
UpdateSurvivalRateTrend(start_new_space_size);
}
Counters::objs_since_last_young.Set(0);
// Update relocatables.
Relocatable::PostGarbageCollectionProcessing();
if (collector == MARK_COMPACTOR) {
// Register the amount of external allocated memory.
amount_of_external_allocated_memory_at_last_global_gc_ =
amount_of_external_allocated_memory_;
}
GCCallbackFlags callback_flags = tracer->is_compacting()
? kGCCallbackFlagCompacted
: kNoGCCallbackFlags;
for (int i = 0; i < gc_epilogue_callbacks_.length(); ++i) {
if (gc_type & gc_epilogue_callbacks_[i].gc_type) {
gc_epilogue_callbacks_[i].callback(gc_type, callback_flags);
}
}
if (collector == MARK_COMPACTOR && global_gc_epilogue_callback_) {
ASSERT(!allocation_allowed_);
GCTracer::Scope scope(tracer, GCTracer::Scope::EXTERNAL);
global_gc_epilogue_callback_();
}
VerifySymbolTable();
}
void Heap::MarkCompact(GCTracer* tracer) {
gc_state_ = MARK_COMPACT;
LOG(ResourceEvent("markcompact", "begin"));
MarkCompactCollector::Prepare(tracer);
bool is_compacting = MarkCompactCollector::IsCompacting();
if (is_compacting) {
mc_count_++;
} else {
ms_count_++;
}
tracer->set_full_gc_count(mc_count_ + ms_count_);
MarkCompactPrologue(is_compacting);
MarkCompactCollector::CollectGarbage();
LOG(ResourceEvent("markcompact", "end"));
gc_state_ = NOT_IN_GC;
Shrink();
Counters::objs_since_last_full.Set(0);
contexts_disposed_ = 0;
}
void Heap::MarkCompactPrologue(bool is_compacting) {
// At any old GC clear the keyed lookup cache to enable collection of unused
// maps.
KeyedLookupCache::Clear();
ContextSlotCache::Clear();
DescriptorLookupCache::Clear();
CompilationCache::MarkCompactPrologue();
CompletelyClearInstanceofCache();
if (is_compacting) FlushNumberStringCache();
ClearNormalizedMapCaches();
}
Object* Heap::FindCodeObject(Address a) {
Object* obj = code_space_->FindObject(a);
if (obj->IsFailure()) {
obj = lo_space_->FindObject(a);
}
ASSERT(!obj->IsFailure());
return obj;
}
// Helper class for copying HeapObjects
class ScavengeVisitor: public ObjectVisitor {
public:
void VisitPointer(Object** p) { ScavengePointer(p); }
void VisitPointers(Object** start, Object** end) {
// Copy all HeapObject pointers in [start, end)
for (Object** p = start; p < end; p++) ScavengePointer(p);
}
private:
void ScavengePointer(Object** p) {
Object* object = *p;
if (!Heap::InNewSpace(object)) return;
Heap::ScavengeObject(reinterpret_cast<HeapObject**>(p),
reinterpret_cast<HeapObject*>(object));
}
};
// A queue of objects promoted during scavenge. Each object is accompanied
// by it's size to avoid dereferencing a map pointer for scanning.
class PromotionQueue {
public:
void Initialize(Address start_address) {
front_ = rear_ = reinterpret_cast<intptr_t*>(start_address);
}
bool is_empty() { return front_ <= rear_; }
void insert(HeapObject* target, int size) {
*(--rear_) = reinterpret_cast<intptr_t>(target);
*(--rear_) = size;
// Assert no overflow into live objects.
ASSERT(reinterpret_cast<Address>(rear_) >= Heap::new_space()->top());
}
void remove(HeapObject** target, int* size) {
*target = reinterpret_cast<HeapObject*>(*(--front_));
*size = static_cast<int>(*(--front_));
// Assert no underflow.
ASSERT(front_ >= rear_);
}
private:
// The front of the queue is higher in memory than the rear.
intptr_t* front_;
intptr_t* rear_;
};
// Shared state read by the scavenge collector and set by ScavengeObject.
static PromotionQueue promotion_queue;
#ifdef DEBUG
// Visitor class to verify pointers in code or data space do not point into
// new space.
class VerifyNonPointerSpacePointersVisitor: public ObjectVisitor {
public:
void VisitPointers(Object** start, Object**end) {
for (Object** current = start; current < end; current++) {
if ((*current)->IsHeapObject()) {
ASSERT(!Heap::InNewSpace(HeapObject::cast(*current)));
}
}
}
};
static void VerifyNonPointerSpacePointers() {
// Verify that there are no pointers to new space in spaces where we
// do not expect them.
VerifyNonPointerSpacePointersVisitor v;
HeapObjectIterator code_it(Heap::code_space());
for (HeapObject* object = code_it.next();
object != NULL; object = code_it.next())
object->Iterate(&v);
HeapObjectIterator data_it(Heap::old_data_space());
for (HeapObject* object = data_it.next();
object != NULL; object = data_it.next())
object->Iterate(&v);
}
#endif
void Heap::CheckNewSpaceExpansionCriteria() {
if (new_space_.Capacity() < new_space_.MaximumCapacity() &&
survived_since_last_expansion_ > new_space_.Capacity()) {
// Grow the size of new space if there is room to grow and enough
// data has survived scavenge since the last expansion.
new_space_.Grow();
survived_since_last_expansion_ = 0;
}
}
void Heap::Scavenge() {
#ifdef DEBUG
if (FLAG_enable_slow_asserts) VerifyNonPointerSpacePointers();
#endif
gc_state_ = SCAVENGE;
Page::FlipMeaningOfInvalidatedWatermarkFlag();
#ifdef DEBUG
VerifyPageWatermarkValidity(old_pointer_space_, ALL_VALID);
VerifyPageWatermarkValidity(map_space_, ALL_VALID);
#endif
// We do not update an allocation watermark of the top page during linear
// allocation to avoid overhead. So to maintain the watermark invariant
// we have to manually cache the watermark and mark the top page as having an
// invalid watermark. This guarantees that dirty regions iteration will use a
// correct watermark even if a linear allocation happens.
old_pointer_space_->FlushTopPageWatermark();
map_space_->FlushTopPageWatermark();
// Implements Cheney's copying algorithm
LOG(ResourceEvent("scavenge", "begin"));
// Clear descriptor cache.
DescriptorLookupCache::Clear();
// Used for updating survived_since_last_expansion_ at function end.
int survived_watermark = PromotedSpaceSize();
CheckNewSpaceExpansionCriteria();
// 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_.ToSpaceLow();
promotion_queue.Initialize(new_space_.ToSpaceHigh());
ScavengeVisitor scavenge_visitor;
// Copy roots.
IterateRoots(&scavenge_visitor, VISIT_ALL_IN_SCAVENGE);
// Copy objects reachable from the old generation. By definition,
// there are no intergenerational pointers in code or data spaces.
IterateDirtyRegions(old_pointer_space_,
&IteratePointersInDirtyRegion,
&ScavengePointer,
WATERMARK_CAN_BE_INVALID);
IterateDirtyRegions(map_space_,
&IteratePointersInDirtyMapsRegion,
&ScavengePointer,
WATERMARK_CAN_BE_INVALID);
lo_space_->IterateDirtyRegions(&ScavengePointer);
// Copy objects reachable from cells by scavenging cell values directly.
HeapObjectIterator cell_iterator(cell_space_);
for (HeapObject* cell = cell_iterator.next();
cell != NULL; cell = cell_iterator.next()) {
if (cell->IsJSGlobalPropertyCell()) {
Address value_address =
reinterpret_cast<Address>(cell) +
(JSGlobalPropertyCell::kValueOffset - kHeapObjectTag);
scavenge_visitor.VisitPointer(reinterpret_cast<Object**>(value_address));
}
}
new_space_front = DoScavenge(&scavenge_visitor, new_space_front);
UpdateNewSpaceReferencesInExternalStringTable(
&UpdateNewSpaceReferenceInExternalStringTableEntry);
ASSERT(new_space_front == new_space_.top());
// Set age mark.
new_space_.set_age_mark(new_space_.top());
// Update how much has survived scavenge.
IncrementYoungSurvivorsCounter(
(PromotedSpaceSize() - survived_watermark) + new_space_.Size());
LOG(ResourceEvent("scavenge", "end"));
gc_state_ = NOT_IN_GC;
}
String* Heap::UpdateNewSpaceReferenceInExternalStringTableEntry(Object** p) {
MapWord first_word = HeapObject::cast(*p)->map_word();
if (!first_word.IsForwardingAddress()) {
// Unreachable external string can be finalized.
FinalizeExternalString(String::cast(*p));
return NULL;
}
// String is still reachable.
return String::cast(first_word.ToForwardingAddress());
}
void Heap::UpdateNewSpaceReferencesInExternalStringTable(
ExternalStringTableUpdaterCallback updater_func) {
ExternalStringTable::Verify();
if (ExternalStringTable::new_space_strings_.is_empty()) return;
Object** start = &ExternalStringTable::new_space_strings_[0];
Object** end = start + ExternalStringTable::new_space_strings_.length();
Object** last = start;
for (Object** p = start; p < end; ++p) {
ASSERT(Heap::InFromSpace(*p));
String* target = updater_func(p);
if (target == NULL) continue;
ASSERT(target->IsExternalString());
if (Heap::InNewSpace(target)) {
// String is still in new space. Update the table entry.
*last = target;
++last;
} else {
// String got promoted. Move it to the old string list.
ExternalStringTable::AddOldString(target);
}
}
ASSERT(last <= end);
ExternalStringTable::ShrinkNewStrings(static_cast<int>(last - start));
}
class NewSpaceScavenger : public StaticNewSpaceVisitor<NewSpaceScavenger> {
public:
static inline void VisitPointer(Object** p) {
Object* object = *p;
if (!Heap::InNewSpace(object)) return;
Heap::ScavengeObject(reinterpret_cast<HeapObject**>(p),
reinterpret_cast<HeapObject*>(object));
}
};
Address Heap::DoScavenge(ObjectVisitor* scavenge_visitor,
Address new_space_front) {
do {
ASSERT(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()) {
HeapObject* object = HeapObject::FromAddress(new_space_front);
new_space_front += NewSpaceScavenger::IterateBody(object->map(), object);
}
// Promote and process all the to-be-promoted objects.
while (!promotion_queue.is_empty()) {
HeapObject* target;
int size;
promotion_queue.remove(&target, &size);
// Promoted object might be already partially visited
// during dirty regions iteration. Thus we search specificly
// for pointers to from semispace instead of looking for pointers
// to new space.
ASSERT(!target->IsMap());
IterateAndMarkPointersToFromSpace(target->address(),
target->address() + size,
&ScavengePointer);
}
// 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;
}
class ScavengingVisitor : public StaticVisitorBase {
public:
static void Initialize() {
table_.Register(kVisitSeqAsciiString, &EvacuateSeqAsciiString);
table_.Register(kVisitSeqTwoByteString, &EvacuateSeqTwoByteString);
table_.Register(kVisitShortcutCandidate, &EvacuateShortcutCandidate);
table_.Register(kVisitByteArray, &EvacuateByteArray);
table_.Register(kVisitFixedArray, &EvacuateFixedArray);
typedef ObjectEvacuationStrategy<POINTER_OBJECT> PointerObject;
table_.Register(kVisitConsString,
&ObjectEvacuationStrategy<POINTER_OBJECT>::
VisitSpecialized<ConsString::kSize>);
table_.Register(kVisitSharedFunctionInfo,
&ObjectEvacuationStrategy<POINTER_OBJECT>::
VisitSpecialized<SharedFunctionInfo::kSize>);
table_.Register(kVisitJSFunction,
&ObjectEvacuationStrategy<POINTER_OBJECT>::
VisitSpecialized<JSFunction::kSize>);
table_.RegisterSpecializations<ObjectEvacuationStrategy<DATA_OBJECT>,
kVisitDataObject,
kVisitDataObjectGeneric>();
table_.RegisterSpecializations<ObjectEvacuationStrategy<POINTER_OBJECT>,
kVisitJSObject,
kVisitJSObjectGeneric>();
table_.RegisterSpecializations<ObjectEvacuationStrategy<POINTER_OBJECT>,
kVisitStruct,
kVisitStructGeneric>();
}
static inline void Scavenge(Map* map, HeapObject** slot, HeapObject* obj) {
table_.GetVisitor(map)(map, slot, obj);
}
private:
enum ObjectContents { DATA_OBJECT, POINTER_OBJECT };
enum SizeRestriction { SMALL, UNKNOWN_SIZE };
#if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
static void RecordCopiedObject(HeapObject* obj) {
bool should_record = false;
#ifdef DEBUG
should_record = FLAG_heap_stats;
#endif
#ifdef ENABLE_LOGGING_AND_PROFILING
should_record = should_record || FLAG_log_gc;
#endif
if (should_record) {
if (Heap::new_space()->Contains(obj)) {
Heap::new_space()->RecordAllocation(obj);
} else {
Heap::new_space()->RecordPromotion(obj);
}
}
}
#endif // defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
// Helper function used by CopyObject to copy a source object to an
// allocated target object and update the forwarding pointer in the source
// object. Returns the target object.
INLINE(static HeapObject* MigrateObject(HeapObject* source,
HeapObject* target,
int size)) {
// Copy the content of source to target.
Heap::CopyBlock(target->address(), source->address(), size);
// Set the forwarding address.
source->set_map_word(MapWord::FromForwardingAddress(target));
#if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
// Update NewSpace stats if necessary.
RecordCopiedObject(target);
#endif
HEAP_PROFILE(ObjectMoveEvent(source->address(), target->address()));
#if defined(ENABLE_LOGGING_AND_PROFILING)
if (Logger::is_logging() || CpuProfiler::is_profiling()) {
if (target->IsJSFunction()) {
PROFILE(FunctionMoveEvent(source->address(), target->address()));
PROFILE(FunctionCreateEventFromMove(JSFunction::cast(target), source));
}
}
#endif
return target;
}
template<ObjectContents object_contents, SizeRestriction size_restriction>
static inline void EvacuateObject(Map* map,
HeapObject** slot,
HeapObject* object,
int object_size) {
ASSERT((size_restriction != SMALL) ||
(object_size <= Page::kMaxHeapObjectSize));
ASSERT(object->Size() == object_size);
if (Heap::ShouldBePromoted(object->address(), object_size)) {
Object* result;
if ((size_restriction != SMALL) &&
(object_size > Page::kMaxHeapObjectSize)) {
result = Heap::lo_space()->AllocateRawFixedArray(object_size);
} else {
if (object_contents == DATA_OBJECT) {
result = Heap::old_data_space()->AllocateRaw(object_size);
} else {
result = Heap::old_pointer_space()->AllocateRaw(object_size);
}
}
if (!result->IsFailure()) {
HeapObject* target = HeapObject::cast(result);
*slot = MigrateObject(object, target, object_size);
if (object_contents == POINTER_OBJECT) {
promotion_queue.insert(target, object_size);
}
Heap::tracer()->increment_promoted_objects_size(object_size);
return;
}
}
Object* result = Heap::new_space()->AllocateRaw(object_size);
ASSERT(!result->IsFailure());
*slot = MigrateObject(object, HeapObject::cast(result), object_size);
return;
}
static inline void EvacuateFixedArray(Map* map,
HeapObject** slot,
HeapObject* object) {
int object_size = FixedArray::BodyDescriptor::SizeOf(map, object);
EvacuateObject<POINTER_OBJECT, UNKNOWN_SIZE>(map,
slot,
object,
object_size);
}
static inline void EvacuateByteArray(Map* map,
HeapObject** slot,
HeapObject* object) {
int object_size = reinterpret_cast<ByteArray*>(object)->ByteArraySize();
EvacuateObject<DATA_OBJECT, UNKNOWN_SIZE>(map, slot, object, object_size);
}
static inline void EvacuateSeqAsciiString(Map* map,
HeapObject** slot,
HeapObject* object) {
int object_size = SeqAsciiString::cast(object)->
SeqAsciiStringSize(map->instance_type());
EvacuateObject<DATA_OBJECT, UNKNOWN_SIZE>(map, slot, object, object_size);
}
static inline void EvacuateSeqTwoByteString(Map* map,
HeapObject** slot,
HeapObject* object) {
int object_size = SeqTwoByteString::cast(object)->
SeqTwoByteStringSize(map->instance_type());
EvacuateObject<DATA_OBJECT, UNKNOWN_SIZE>(map, slot, object, object_size);
}
static inline bool IsShortcutCandidate(int type) {
return ((type & kShortcutTypeMask) == kShortcutTypeTag);
}
static inline void EvacuateShortcutCandidate(Map* map,
HeapObject** slot,
HeapObject* object) {
ASSERT(IsShortcutCandidate(map->instance_type()));
if (ConsString::cast(object)->unchecked_second() == Heap::empty_string()) {
HeapObject* first =
HeapObject::cast(ConsString::cast(object)->unchecked_first());
*slot = first;
if (!Heap::InNewSpace(first)) {
object->set_map_word(MapWord::FromForwardingAddress(first));
return;
}
MapWord first_word = first->map_word();
if (first_word.IsForwardingAddress()) {
HeapObject* target = first_word.ToForwardingAddress();
*slot = target;
object->set_map_word(MapWord::FromForwardingAddress(target));
return;
}
Scavenge(first->map(), slot, first);
object->set_map_word(MapWord::FromForwardingAddress(*slot));
return;
}
int object_size = ConsString::kSize;
EvacuateObject<POINTER_OBJECT, SMALL>(map, slot, object, object_size);
}
template<ObjectContents object_contents>
class ObjectEvacuationStrategy {
public:
template<int object_size>
static inline void VisitSpecialized(Map* map,
HeapObject** slot,
HeapObject* object) {
EvacuateObject<object_contents, SMALL>(map, slot, object, object_size);
}
static inline void Visit(Map* map,
HeapObject** slot,
HeapObject* object) {
int object_size = map->instance_size();
EvacuateObject<object_contents, SMALL>(map, slot, object, object_size);
}
};
typedef void (*Callback)(Map* map, HeapObject** slot, HeapObject* object);
static VisitorDispatchTable<Callback> table_;
};
VisitorDispatchTable<ScavengingVisitor::Callback> ScavengingVisitor::table_;
void Heap::ScavengeObjectSlow(HeapObject** p, HeapObject* object) {
ASSERT(InFromSpace(object));
MapWord first_word = object->map_word();
ASSERT(!first_word.IsForwardingAddress());
Map* map = first_word.ToMap();
ScavengingVisitor::Scavenge(map, p, object);
}
void Heap::ScavengePointer(HeapObject** p) {
ScavengeObject(p, *p);
}
Object* Heap::AllocatePartialMap(InstanceType instance_type,
int instance_size) {
Object* result = AllocateRawMap();
if (result->IsFailure()) return result;
// Map::cast cannot be used due to uninitialized map field.
reinterpret_cast<Map*>(result)->set_map(raw_unchecked_meta_map());
reinterpret_cast<Map*>(result)->set_instance_type(instance_type);
reinterpret_cast<Map*>(result)->set_instance_size(instance_size);
reinterpret_cast<Map*>(result)->
set_visitor_id(
StaticVisitorBase::GetVisitorId(instance_type, instance_size));
reinterpret_cast<Map*>(result)->set_inobject_properties(0);
reinterpret_cast<Map*>(result)->set_pre_allocated_property_fields(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);
return result;
}
Object* Heap::AllocateMap(InstanceType instance_type, int instance_size) {
Object* result = AllocateRawMap();
if (result->IsFailure()) return result;
Map* map = reinterpret_cast<Map*>(result);
map->set_map(meta_map());
map->set_instance_type(instance_type);
map->set_visitor_id(
StaticVisitorBase::GetVisitorId(instance_type, instance_size));
map->set_prototype(null_value());
map->set_constructor(null_value());
map->set_instance_size(instance_size);
map->set_inobject_properties(0);
map->set_pre_allocated_property_fields(0);
map->set_instance_descriptors(empty_descriptor_array());
map->set_code_cache(empty_fixed_array());
map->set_unused_property_fields(0);
map->set_bit_field(0);
map->set_bit_field2((1 << Map::kIsExtensible) | (1 << Map::kHasFastElements));
// If the map object is aligned fill the padding area with Smi 0 objects.
if (Map::kPadStart < Map::kSize) {
memset(reinterpret_cast<byte*>(map) + Map::kPadStart - kHeapObjectTag,
0,
Map::kSize - Map::kPadStart);
}
return map;
}
Object* Heap::AllocateCodeCache() {
Object* result = AllocateStruct(CODE_CACHE_TYPE);
if (result->IsFailure()) return result;
CodeCache* code_cache = CodeCache::cast(result);
code_cache->set_default_cache(empty_fixed_array());
code_cache->set_normal_type_cache(undefined_value());
return code_cache;
}
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::ConstantSymbolTable Heap::constant_symbol_table[] = {
#define CONSTANT_SYMBOL_ELEMENT(name, contents) \
{contents, k##name##RootIndex},
SYMBOL_LIST(CONSTANT_SYMBOL_ELEMENT)
#undef CONSTANT_SYMBOL_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
};
bool Heap::CreateInitialMaps() {
Object* obj = AllocatePartialMap(MAP_TYPE, Map::kSize);
if (obj->IsFailure()) 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);
obj = AllocatePartialMap(FIXED_ARRAY_TYPE, kVariableSizeSentinel);
if (obj->IsFailure()) return false;
set_fixed_array_map(Map::cast(obj));
obj = AllocatePartialMap(ODDBALL_TYPE, Oddball::kSize);
if (obj->IsFailure()) return false;
set_oddball_map(Map::cast(obj));
// Allocate the empty array.
obj = AllocateEmptyFixedArray();
if (obj->IsFailure()) return false;
set_empty_fixed_array(FixedArray::cast(obj));
obj = Allocate(oddball_map(), OLD_DATA_SPACE);
if (obj->IsFailure()) return false;
set_null_value(obj);
// Allocate the empty descriptor array.
obj = AllocateEmptyFixedArray();
if (obj->IsFailure()) return false;
set_empty_descriptor_array(DescriptorArray::cast(obj));
// Fix the instance_descriptors for the existing maps.
meta_map()->set_instance_descriptors(empty_descriptor_array());
meta_map()->set_code_cache(empty_fixed_array());
fixed_array_map()->set_instance_descriptors(empty_descriptor_array());
fixed_array_map()->set_code_cache(empty_fixed_array());
oddball_map()->set_instance_descriptors(empty_descriptor_array());
oddball_map()->set_code_cache(empty_fixed_array());
// Fix prototype object for existing maps.
meta_map()->set_prototype(null_value());
meta_map()->set_constructor(null_value());
fixed_array_map()->set_prototype(null_value());
fixed_array_map()->set_constructor(null_value());
oddball_map()->set_prototype(null_value());
oddball_map()->set_constructor(null_value());
obj = AllocateMap(FIXED_ARRAY_TYPE, kVariableSizeSentinel);
if (obj->IsFailure()) return false;
set_fixed_cow_array_map(Map::cast(obj));
ASSERT(fixed_array_map() != fixed_cow_array_map());
obj = AllocateMap(HEAP_NUMBER_TYPE, HeapNumber::kSize);
if (obj->IsFailure()) return false;
set_heap_number_map(Map::cast(obj));
obj = AllocateMap(PROXY_TYPE, Proxy::kSize);
if (obj->IsFailure()) return false;
set_proxy_map(Map::cast(obj));
for (unsigned i = 0; i < ARRAY_SIZE(string_type_table); i++) {
const StringTypeTable& entry = string_type_table[i];
obj = AllocateMap(entry.type, entry.size);
if (obj->IsFailure()) return false;
roots_[entry.index] = Map::cast(obj);
}
obj = AllocateMap(STRING_TYPE, kVariableSizeSentinel);
if (obj->IsFailure()) return false;
set_undetectable_string_map(Map::cast(obj));
Map::cast(obj)->set_is_undetectable();
obj = AllocateMap(ASCII_STRING_TYPE, kVariableSizeSentinel);
if (obj->IsFailure()) return false;
set_undetectable_ascii_string_map(Map::cast(obj));
Map::cast(obj)->set_is_undetectable();
obj = AllocateMap(BYTE_ARRAY_TYPE, kVariableSizeSentinel);
if (obj->IsFailure()) return false;
set_byte_array_map(Map::cast(obj));
obj = AllocateMap(PIXEL_ARRAY_TYPE, PixelArray::kAlignedSize);
if (obj->IsFailure()) return false;
set_pixel_array_map(Map::cast(obj));
obj = AllocateMap(EXTERNAL_BYTE_ARRAY_TYPE,
ExternalArray::kAlignedSize);
if (obj->IsFailure()) return false;
set_external_byte_array_map(Map::cast(obj));
obj = AllocateMap(EXTERNAL_UNSIGNED_BYTE_ARRAY_TYPE,
ExternalArray::kAlignedSize);
if (obj->IsFailure()) return false;
set_external_unsigned_byte_array_map(Map::cast(obj));
obj = AllocateMap(EXTERNAL_SHORT_ARRAY_TYPE,
ExternalArray::kAlignedSize);
if (obj->IsFailure()) return false;
set_external_short_array_map(Map::cast(obj));
obj = AllocateMap(EXTERNAL_UNSIGNED_SHORT_ARRAY_TYPE,
ExternalArray::kAlignedSize);
if (obj->IsFailure()) return false;
set_external_unsigned_short_array_map(Map::cast(obj));
obj = AllocateMap(EXTERNAL_INT_ARRAY_TYPE,
ExternalArray::kAlignedSize);
if (obj->IsFailure()) return false;
set_external_int_array_map(Map::cast(obj));
obj = AllocateMap(EXTERNAL_UNSIGNED_INT_ARRAY_TYPE,
ExternalArray::kAlignedSize);
if (obj->IsFailure()) return false;
set_external_unsigned_int_array_map(Map::cast(obj));
obj = AllocateMap(EXTERNAL_FLOAT_ARRAY_TYPE,
ExternalArray::kAlignedSize);
if (obj->IsFailure()) return false;
set_external_float_array_map(Map::cast(obj));
obj = AllocateMap(CODE_TYPE, kVariableSizeSentinel);
if (obj->IsFailure()) return false;
set_code_map(Map::cast(obj));
obj = AllocateMap(JS_GLOBAL_PROPERTY_CELL_TYPE,
JSGlobalPropertyCell::kSize);
if (obj->IsFailure()) return false;
set_global_property_cell_map(Map::cast(obj));
obj = AllocateMap(FILLER_TYPE, kPointerSize);
if (obj->IsFailure()) return false;
set_one_pointer_filler_map(Map::cast(obj));
obj = AllocateMap(FILLER_TYPE, 2 * kPointerSize);
if (obj->IsFailure()) return false;
set_two_pointer_filler_map(Map::cast(obj));
for (unsigned i = 0; i < ARRAY_SIZE(struct_table); i++) {
const StructTable& entry = struct_table[i];
obj = AllocateMap(entry.type, entry.size);
if (obj->IsFailure()) return false;
roots_[entry.index] = Map::cast(obj);
}
obj = AllocateMap(FIXED_ARRAY_TYPE, kVariableSizeSentinel);
if (obj->IsFailure()) return false;
set_hash_table_map(Map::cast(obj));
obj = AllocateMap(FIXED_ARRAY_TYPE, kVariableSizeSentinel);
if (obj->IsFailure()) return false;
set_context_map(Map::cast(obj));
obj = AllocateMap(FIXED_ARRAY_TYPE, kVariableSizeSentinel);
if (obj->IsFailure()) return false;
set_catch_context_map(Map::cast(obj));
obj = AllocateMap(FIXED_ARRAY_TYPE, kVariableSizeSentinel);
if (obj->IsFailure()) return false;
set_global_context_map(Map::cast(obj));
obj = AllocateMap(SHARED_FUNCTION_INFO_TYPE,
SharedFunctionInfo::kAlignedSize);
if (obj->IsFailure()) return false;
set_shared_function_info_map(Map::cast(obj));
ASSERT(!Heap::InNewSpace(Heap::empty_fixed_array()));
return true;
}
Object* Heap::AllocateHeapNumber(double value, PretenureFlag pretenure) {
// Statically ensure that it is safe to allocate heap numbers in paged
// spaces.
STATIC_ASSERT(HeapNumber::kSize <= Page::kMaxHeapObjectSize);
AllocationSpace space = (pretenure == TENURED) ? OLD_DATA_SPACE : NEW_SPACE;
Object* result = AllocateRaw(HeapNumber::kSize, space, OLD_DATA_SPACE);
if (result->IsFailure()) return result;
HeapObject::cast(result)->set_map(heap_number_map());
HeapNumber::cast(result)->set_value(value);
return result;
}
Object* Heap::AllocateHeapNumber(double value) {
// Use general version, if we're forced to always allocate.
if (always_allocate()) return AllocateHeapNumber(value, TENURED);
// This version of AllocateHeapNumber is optimized for
// allocation in new space.
STATIC_ASSERT(HeapNumber::kSize <= Page::kMaxHeapObjectSize);
ASSERT(allocation_allowed_ && gc_state_ == NOT_IN_GC);
Object* result = new_space_.AllocateRaw(HeapNumber::kSize);
if (result->IsFailure()) return result;
HeapObject::cast(result)->set_map(heap_number_map());
HeapNumber::cast(result)->set_value(value);
return result;
}
Object* Heap::AllocateJSGlobalPropertyCell(Object* value) {
Object* result = AllocateRawCell();
if (result->IsFailure()) return result;
HeapObject::cast(result)->set_map(global_property_cell_map());
JSGlobalPropertyCell::cast(result)->set_value(value);
return result;
}
Object* Heap::CreateOddball(const char* to_string,
Object* to_number) {
Object* result = Allocate(oddball_map(), OLD_DATA_SPACE);
if (result->IsFailure()) return result;
return Oddball::cast(result)->Initialize(to_string, to_number);
}
bool Heap::CreateApiObjects() {
Object* obj;
obj = AllocateMap(JS_OBJECT_TYPE, JSObject::kHeaderSize);
if (obj->IsFailure()) return false;
set_neander_map(Map::cast(obj));
obj = Heap::AllocateJSObjectFromMap(neander_map());
if (obj->IsFailure()) return false;
Object* elements = AllocateFixedArray(2);
if (elements->IsFailure()) return false;
FixedArray::cast(elements)->set(0, Smi::FromInt(0));
JSObject::cast(obj)->set_elements(FixedArray::cast(elements));
set_message_listeners(JSObject::cast(obj));
return true;
}
void Heap::CreateCEntryStub() {
CEntryStub stub(1);
set_c_entry_code(*stub.GetCode());
}
#if V8_TARGET_ARCH_ARM && !V8_INTERPRETED_REGEXP
void Heap::CreateRegExpCEntryStub() {
RegExpCEntryStub stub;
set_re_c_entry_code(*stub.GetCode());
}
#endif
void Heap::CreateJSEntryStub() {
JSEntryStub stub;
set_js_entry_code(*stub.GetCode());
}
void Heap::CreateJSConstructEntryStub() {
JSConstructEntryStub stub;
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;
// gcc-4.4 has problem generating correct code of following snippet:
// { CEntryStub stub;
// c_entry_code_ = *stub.GetCode();
// }
// { DebuggerStatementStub stub;
// debugger_statement_code_ = *stub.GetCode();
// }
// To workaround the problem, make separate functions without inlining.
Heap::CreateCEntryStub();
Heap::CreateJSEntryStub();
Heap::CreateJSConstructEntryStub();
#if V8_TARGET_ARCH_ARM && !V8_INTERPRETED_REGEXP
Heap::CreateRegExpCEntryStub();
#endif
}
bool Heap::CreateInitialObjects() {
Object* obj;
// The -0 value must be set before NumberFromDouble works.
obj = AllocateHeapNumber(-0.0, TENURED);
if (obj->IsFailure()) return false;
set_minus_zero_value(obj);
ASSERT(signbit(minus_zero_value()->Number()) != 0);
obj = AllocateHeapNumber(OS::nan_value(), TENURED);
if (obj->IsFailure()) return false;
set_nan_value(obj);
obj = Allocate(oddball_map(), OLD_DATA_SPACE);
if (obj->IsFailure()) return false;
set_undefined_value(obj);
ASSERT(!InNewSpace(undefined_value()));
// Allocate initial symbol table.
obj = SymbolTable::Allocate(kInitialSymbolTableSize);
if (obj->IsFailure()) return false;
// Don't use set_symbol_table() due to asserts.
roots_[kSymbolTableRootIndex] = obj;
// Assign the print strings for oddballs after creating symboltable.
Object* symbol = LookupAsciiSymbol("undefined");
if (symbol->IsFailure()) return false;
Oddball::cast(undefined_value())->set_to_string(String::cast(symbol));
Oddball::cast(undefined_value())->set_to_number(nan_value());
// Allocate the null_value
obj = Oddball::cast(null_value())->Initialize("null", Smi::FromInt(0));
if (obj->IsFailure()) return false;
obj = CreateOddball("true", Smi::FromInt(1));
if (obj->IsFailure()) return false;
set_true_value(obj);
obj = CreateOddball("false", Smi::FromInt(0));
if (obj->IsFailure()) return false;
set_false_value(obj);
obj = CreateOddball("hole", Smi::FromInt(-1));
if (obj->IsFailure()) return false;
set_the_hole_value(obj);
obj = CreateOddball("no_interceptor_result_sentinel", Smi::FromInt(-2));
if (obj->IsFailure()) return false;
set_no_interceptor_result_sentinel(obj);
obj = CreateOddball("termination_exception", Smi::FromInt(-3));
if (obj->IsFailure()) return false;
set_termination_exception(obj);
// Allocate the empty string.
obj = AllocateRawAsciiString(0, TENURED);
if (obj->IsFailure()) return false;
set_empty_string(String::cast(obj));
for (unsigned i = 0; i < ARRAY_SIZE(constant_symbol_table); i++) {
obj = LookupAsciiSymbol(constant_symbol_table[i].contents);
if (obj->IsFailure()) return false;
roots_[constant_symbol_table[i].index] = String::cast(obj);
}
// Allocate the hidden symbol which is used to identify the hidden properties
// in JSObjects. The hash code has a special value so that it will not match
// the empty string when searching for the property. It cannot be part of the
// loop above because it needs to be allocated manually with the special
// hash code in place. The hash code for the hidden_symbol is zero to ensure
// that it will always be at the first entry in property descriptors.
obj = AllocateSymbol(CStrVector(""), 0, String::kZeroHash);
if (obj->IsFailure()) return false;
hidden_symbol_ = String::cast(obj);
// Allocate the proxy for __proto__.
obj = AllocateProxy((Address) &Accessors::ObjectPrototype);
if (obj->IsFailure()) return false;
set_prototype_accessors(Proxy::cast(obj));
// Allocate the code_stubs dictionary. The initial size is set to avoid
// expanding the dictionary during bootstrapping.
obj = NumberDictionary::Allocate(128);
if (obj->IsFailure()) return false;
set_code_stubs(NumberDictionary::cast(obj));
// Allocate the non_monomorphic_cache used in stub-cache.cc. The initial size
// is set to avoid expanding the dictionary during bootstrapping.
obj = NumberDictionary::Allocate(64);
if (obj->IsFailure()) return false;
set_non_monomorphic_cache(NumberDictionary::cast(obj));
set_instanceof_cache_function(Smi::FromInt(0));
set_instanceof_cache_map(Smi::FromInt(0));
set_instanceof_cache_answer(Smi::FromInt(0));
CreateFixedStubs();
// Allocate the dictionary of intrinsic function names.
obj = StringDictionary::Allocate(Runtime::kNumFunctions);
if (obj->IsFailure()) return false;
obj = Runtime::InitializeIntrinsicFunctionNames(obj);
if (obj->IsFailure()) return false;
set_intrinsic_function_names(StringDictionary::cast(obj));
if (InitializeNumberStringCache()->IsFailure()) return false;
// Allocate cache for single character ASCII strings.
obj = AllocateFixedArray(String::kMaxAsciiCharCode + 1, TENURED);
if (obj->IsFailure()) return false;
set_single_character_string_cache(FixedArray::cast(obj));
// Allocate cache for external strings pointing to native source code.
obj = AllocateFixedArray(Natives::GetBuiltinsCount());
if (obj->IsFailure()) return false;
set_natives_source_cache(FixedArray::cast(obj));
// Handling of script id generation is in Factory::NewScript.
set_last_script_id(undefined_value());
// Initialize keyed lookup cache.
KeyedLookupCache::Clear();
// Initialize context slot cache.
ContextSlotCache::Clear();
// Initialize descriptor cache.
DescriptorLookupCache::Clear();
// Initialize compilation cache.
CompilationCache::Clear();
return true;
}
Object* Heap::InitializeNumberStringCache() {
// Compute the size of the number string cache based on the max heap size.
// max_semispace_size_ == 512 KB => number_string_cache_size = 32.
// max_semispace_size_ == 8 MB => number_string_cache_size = 16KB.
int number_string_cache_size = max_semispace_size_ / 512;
number_string_cache_size = Max(32, Min(16*KB, number_string_cache_size));
Object* obj = AllocateFixedArray(number_string_cache_size * 2, TENURED);
if (!obj->IsFailure()) set_number_string_cache(FixedArray::cast(obj));
return obj;
}
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);
}
}
static inline int double_get_hash(double d) {
DoubleRepresentation rep(d);
return static_cast<int>(rep.bits) ^ static_cast<int>(rep.bits >> 32);
}
static inline int smi_get_hash(Smi* smi) {
return smi->value();
}
Object* Heap::GetNumberStringCache(Object* number) {
int hash;
int mask = (number_string_cache()->length() >> 1) - 1;
if (number->IsSmi()) {
hash = smi_get_hash(Smi::cast(number)) & mask;
} else {
hash = double_get_hash(number->Number()) & mask;
}
Object* key = number_string_cache()->get(hash * 2);
if (key == number) {
return String::cast(number_string_cache()->get(hash * 2 + 1));
} else if (key->IsHeapNumber() &&
number->IsHeapNumber() &&
key->Number() == number->Number()) {
return String::cast(number_string_cache()->get(hash * 2 + 1));
}
return undefined_value();
}
void Heap::SetNumberStringCache(Object* number, String* string) {
int hash;
int mask = (number_string_cache()->length() >> 1) - 1;
if (number->IsSmi()) {
hash = smi_get_hash(Smi::cast(number)) & mask;
number_string_cache()->set(hash * 2, Smi::cast(number));
} else {
hash = double_get_hash(number->Number()) & mask;
number_string_cache()->set(hash * 2, number);
}
number_string_cache()->set(hash * 2 + 1, string);
}
Object* Heap::NumberToString(Object* number, bool check_number_string_cache) {
Counters::number_to_string_runtime.Increment();
if (check_number_string_cache) {
Object* cached = GetNumberStringCache(number);
if (cached != undefined_value()) {
return cached;
}
}
char arr[100];
Vector<char> buffer(arr, ARRAY_SIZE(arr));
const char* str;
if (number->IsSmi()) {
int num = Smi::cast(number)->value();
str = IntToCString(num, buffer);
} else {
double num = HeapNumber::cast(number)->value();
str = DoubleToCString(num, buffer);
}
Object* result = AllocateStringFromAscii(CStrVector(str));
if (!result->IsFailure()) {
SetNumberStringCache(number, String::cast(result));
}
return result;
}
Map* Heap::MapForExternalArrayType(ExternalArrayType array_type) {
return Map::cast(roots_[RootIndexForExternalArrayType(array_type)]);
}
Heap::RootListIndex Heap::RootIndexForExternalArrayType(
ExternalArrayType array_type) {
switch (array_type) {
case kExternalByteArray:
return kExternalByteArrayMapRootIndex;
case kExternalUnsignedByteArray:
return kExternalUnsignedByteArrayMapRootIndex;
case kExternalShortArray:
return kExternalShortArrayMapRootIndex;
case kExternalUnsignedShortArray:
return kExternalUnsignedShortArrayMapRootIndex;
case kExternalIntArray:
return kExternalIntArrayMapRootIndex;
case kExternalUnsignedIntArray:
return kExternalUnsignedIntArrayMapRootIndex;
case kExternalFloatArray:
return kExternalFloatArrayMapRootIndex;
default:
UNREACHABLE();
return kUndefinedValueRootIndex;
}
}
Object* Heap::NumberFromDouble(double value, PretenureFlag pretenure) {
// We need to distinguish the minus zero value and this cannot be
// done after conversion to int. Doing this by comparing bit
// patterns is faster than using fpclassify() et al.
static const DoubleRepresentation minus_zero(-0.0);
DoubleRepresentation rep(value);
if (rep.bits == minus_zero.bits) {
return AllocateHeapNumber(-0.0, pretenure);
}
int int_value = FastD2I(value);
if (value == int_value && Smi::IsValid(int_value)) {
return Smi::FromInt(int_value);
}
// Materialize the value in the heap.
return AllocateHeapNumber(value, pretenure);
}
Object* Heap::AllocateProxy(Address proxy, PretenureFlag pretenure) {
// Statically ensure that it is safe to allocate proxies in paged spaces.
STATIC_ASSERT(Proxy::kSize <= Page::kMaxHeapObjectSize);
AllocationSpace space = (pretenure == TENURED) ? OLD_DATA_SPACE : NEW_SPACE;
Object* result = Allocate(proxy_map(), space);
if (result->IsFailure()) return result;
Proxy::cast(result)->set_proxy(proxy);
return result;
}
Object* Heap::AllocateSharedFunctionInfo(Object* name) {
Object* result = Allocate(shared_function_info_map(), OLD_POINTER_SPACE);
if (result->IsFailure()) return result;
SharedFunctionInfo* share = SharedFunctionInfo::cast(result);
share->set_name(name);
Code* illegal = Builtins::builtin(Builtins::Illegal);
share->set_code(illegal);
share->set_scope_info(SerializedScopeInfo::Empty());
Code* construct_stub = Builtins::builtin(Builtins::JSConstructStubGeneric);
share->set_construct_stub(construct_stub);
share->set_expected_nof_properties(0);
share->set_length(0);
share->set_formal_parameter_count(0);
share->set_instance_class_name(Object_symbol());
share->set_function_data(undefined_value());
share->set_script(undefined_value());
share->set_start_position_and_type(0);
share->set_debug_info(undefined_value());
share->set_inferred_name(empty_string());
share->set_compiler_hints(0);
share->set_initial_map(undefined_value());
share->set_this_property_assignments_count(0);
share->set_this_property_assignments(undefined_value());
share->set_num_literals(0);
share->set_end_position(0);
share->set_function_token_position(0);
return result;
}
// Returns true for a character in a range. Both limits are inclusive.
static inline bool Between(uint32_t character, uint32_t from, uint32_t to) {
// This makes uses of the the unsigned wraparound.
return character - from <= to - from;
}
static inline Object* MakeOrFindTwoCharacterString(uint32_t c1, uint32_t c2) {
String* symbol;
// Numeric strings have a different hash algorithm not known by
// LookupTwoCharsSymbolIfExists, so we skip this step for such strings.
if ((!Between(c1, '0', '9') || !Between(c2, '0', '9')) &&
Heap::symbol_table()->LookupTwoCharsSymbolIfExists(c1, c2, &symbol)) {
return symbol;
// Now we know the length is 2, we might as well make use of that fact
// when building the new string.
} else if ((c1 | c2) <= String::kMaxAsciiCharCodeU) { // We can do this
ASSERT(IsPowerOf2(String::kMaxAsciiCharCodeU + 1)); // because of this.
Object* result = Heap::AllocateRawAsciiString(2);
if (result->IsFailure()) return result;
char* dest = SeqAsciiString::cast(result)->GetChars();
dest[0] = c1;
dest[1] = c2;
return result;
} else {
Object* result = Heap::AllocateRawTwoByteString(2);
if (result->IsFailure()) return result;
uc16* dest = SeqTwoByteString::cast(result)->GetChars();
dest[0] = c1;
dest[1] = c2;
return result;
}
}
Object* Heap::AllocateConsString(String* first, String* second) {
int first_length = first->length();
if (first_length == 0) {
return second;
}
int second_length = second->length();
if (second_length == 0) {
return first;
}
int length = first_length + second_length;
// Optimization for 2-byte strings often used as keys in a decompression
// dictionary. Check whether we already have the string in the symbol
// table to prevent creation of many unneccesary strings.
if (length == 2) {
unsigned c1 = first->Get(0);
unsigned c2 = second->Get(0);
return MakeOrFindTwoCharacterString(c1, c2);
}
bool first_is_ascii = first->IsAsciiRepresentation();
bool second_is_ascii = second->IsAsciiRepresentation();
bool is_ascii = first_is_ascii && second_is_ascii;
// Make sure that an out of memory exception is thrown if the length
// of the new cons string is too large.
if (length > String::kMaxLength || length < 0) {
Top::context()->mark_out_of_memory();
return Failure::OutOfMemoryException();
}
bool is_ascii_data_in_two_byte_string = false;
if (!is_ascii) {
// At least one of the strings uses two-byte representation so we
// can't use the fast case code for short ascii strings below, but
// we can try to save memory if all chars actually fit in ascii.
is_ascii_data_in_two_byte_string =
first->HasOnlyAsciiChars() && second->HasOnlyAsciiChars();
if (is_ascii_data_in_two_byte_string) {
Counters::string_add_runtime_ext_to_ascii.Increment();
}
}
// If the resulting string is small make a flat string.
if (length < String::kMinNonFlatLength) {
ASSERT(first->IsFlat());
ASSERT(second->IsFlat());
if (is_ascii) {
Object* result = AllocateRawAsciiString(length);
if (result->IsFailure()) return result;
// Copy the characters into the new object.
char* dest = SeqAsciiString::cast(result)->GetChars();
// Copy first part.
const char* src;
if (first->IsExternalString()) {
src = ExternalAsciiString::cast(first)->resource()->data();
} else {
src = SeqAsciiString::cast(first)->GetChars();
}
for (int i = 0; i < first_length; i++) *dest++ = src[i];
// Copy second part.
if (second->IsExternalString()) {
src = ExternalAsciiString::cast(second)->resource()->data();
} else {
src = SeqAsciiString::cast(second)->GetChars();
}
for (int i = 0; i < second_length; i++) *dest++ = src[i];
return result;
} else {
if (is_ascii_data_in_two_byte_string) {
Object* result = AllocateRawAsciiString(length);
if (result->IsFailure()) return result;
// Copy the characters into the new object.
char* dest = SeqAsciiString::cast(result)->GetChars();
String::WriteToFlat(first, dest, 0, first_length);
String::WriteToFlat(second, dest + first_length, 0, second_length);
return result;
}
Object* result = AllocateRawTwoByteString(length);
if (result->IsFailure()) return result;
// Copy the characters into the new object.
uc16* dest = SeqTwoByteString::cast(result)->GetChars();
String::WriteToFlat(first, dest, 0, first_length);
String::WriteToFlat(second, dest + first_length, 0, second_length);
return result;
}
}
Map* map = (is_ascii || is_ascii_data_in_two_byte_string) ?
cons_ascii_string_map() : cons_string_map();
Object* result = Allocate(map, NEW_SPACE);
if (result->IsFailure()) return result;
AssertNoAllocation no_gc;
ConsString* cons_string = ConsString::cast(result);
WriteBarrierMode mode = cons_string->GetWriteBarrierMode(no_gc);
cons_string->set_length(length);
cons_string->set_hash_field(String::kEmptyHashField);
cons_string->set_first(first, mode);
cons_string->set_second(second, mode);
return result;
}
Object* Heap::AllocateSubString(String* buffer,
int start,
int end,
PretenureFlag pretenure) {
int length = end - start;
if (length == 1) {
return Heap::LookupSingleCharacterStringFromCode(
buffer->Get(start));
} else if (length == 2) {
// Optimization for 2-byte strings often used as keys in a decompression
// dictionary. Check whether we already have the string in the symbol
// table to prevent creation of many unneccesary strings.
unsigned c1 = buffer->Get(start);
unsigned c2 = buffer->Get(start + 1);
return MakeOrFindTwoCharacterString(c1, c2);
}
// Make an attempt to flatten the buffer to reduce access time.
buffer = buffer->TryFlattenGetString();
Object* result = buffer->IsAsciiRepresentation()
? AllocateRawAsciiString(length, pretenure )
: AllocateRawTwoByteString(length, pretenure);
if (result->IsFailure()) return result;
String* string_result = String::cast(result);
// Copy the characters into the new object.
if (buffer->IsAsciiRepresentation()) {
ASSERT(string_result->IsAsciiRepresentation());
char* dest = SeqAsciiString::cast(string_result)->GetChars();
String::WriteToFlat(buffer, dest, start, end);
} else {
ASSERT(string_result->IsTwoByteRepresentation());
uc16* dest = SeqTwoByteString::cast(string_result)->GetChars();
String::WriteToFlat(buffer, dest, start, end);
}
return result;
}
Object* Heap::AllocateExternalStringFromAscii(
ExternalAsciiString::Resource* resource) {
size_t length = resource->length();
if (length > static_cast<size_t>(String::kMaxLength)) {
Top::context()->mark_out_of_memory();
return Failure::OutOfMemoryException();
}
Map* map = external_ascii_string_map();
Object* result = Allocate(map, NEW_SPACE);
if (result->IsFailure()) return result;
ExternalAsciiString* external_string = ExternalAsciiString::cast(result);
external_string->set_length(static_cast<int>(length));
external_string->set_hash_field(String::kEmptyHashField);
external_string->set_resource(resource);
return result;
}
Object* Heap::AllocateExternalStringFromTwoByte(
ExternalTwoByteString::Resource* resource) {
size_t length = resource->length();
if (length > static_cast<size_t>(String::kMaxLength)) {
Top::context()->mark_out_of_memory();
return Failure::OutOfMemoryException();
}
// For small strings we check whether the resource contains only
// ascii characters. If yes, we use a different string map.
bool is_ascii = true;
if (length >= static_cast<size_t>(String::kMinNonFlatLength)) {
is_ascii = false;
} else {
const uc16* data = resource->data();
for (size_t i = 0; i < length; i++) {
if (data[i] > String::kMaxAsciiCharCode) {
is_ascii = false;
break;
}
}
}
Map* map = is_ascii ?
Heap::external_string_with_ascii_data_map() : Heap::external_string_map();
Object* result = Allocate(map, NEW_SPACE);
if (result->IsFailure()) return result;
ExternalTwoByteString* external_string = ExternalTwoByteString::cast(result);
external_string->set_length(static_cast<int>(length));
external_string->set_hash_field(String::kEmptyHashField);
external_string->set_resource(resource);
return result;
}
Object* Heap::LookupSingleCharacterStringFromCode(uint16_t code) {
if (code <= String::kMaxAsciiCharCode) {
Object* value = Heap::single_character_string_cache()->get(code);
if (value != Heap::undefined_value()) return value;
char buffer[1];
buffer[0] = static_cast<char>(code);
Object* result = LookupSymbol(Vector<const char>(buffer, 1));
if (result->IsFailure()) return result;
Heap::single_character_string_cache()->set(code, result);
return result;
}
Object* result = Heap::AllocateRawTwoByteString(1);
if (result->IsFailure()) return result;
String* answer = String::cast(result);
answer->Set(0, code);
return answer;
}
Object* Heap::AllocateByteArray(int length, PretenureFlag pretenure) {
if (length < 0 || length > ByteArray::kMaxLength) {
return Failure::OutOfMemoryException();
}
if (pretenure == NOT_TENURED) {
return AllocateByteArray(length);
}
int size = ByteArray::SizeFor(length);
Object* result = (size <= MaxObjectSizeInPagedSpace())
? old_data_space_->AllocateRaw(size)
: lo_space_->AllocateRaw(size);
if (result->IsFailure()) return result;
reinterpret_cast<ByteArray*>(result)->set_map(byte_array_map());
reinterpret_cast<ByteArray*>(result)->set_length(length);
return result;
}
Object* Heap::AllocateByteArray(int length) {
if (length < 0 || length > ByteArray::kMaxLength) {
return Failure::OutOfMemoryException();
}
int size = ByteArray::SizeFor(length);
AllocationSpace space =
(size > MaxObjectSizeInPagedSpace()) ? LO_SPACE : NEW_SPACE;
Object* result = AllocateRaw(size, space, OLD_DATA_SPACE);
if (result->IsFailure()) return result;
reinterpret_cast<ByteArray*>(result)->set_map(byte_array_map());
reinterpret_cast<ByteArray*>(result)->set_length(length);
return result;
}
void Heap::CreateFillerObjectAt(Address addr, int size) {
if (size == 0) return;
HeapObject* filler = HeapObject::FromAddress(addr);
if (size == kPointerSize) {
filler->set_map(one_pointer_filler_map());
} else if (size == 2 * kPointerSize) {
filler->set_map(two_pointer_filler_map());
} else {
filler->set_map(byte_array_map());
ByteArray::cast(filler)->set_length(ByteArray::LengthFor(size));
}
}
Object* Heap::AllocatePixelArray(int length,
uint8_t* external_pointer,
PretenureFlag pretenure) {
AllocationSpace space = (pretenure == TENURED) ? OLD_DATA_SPACE : NEW_SPACE;
Object* result = AllocateRaw(PixelArray::kAlignedSize, space, OLD_DATA_SPACE);
if (result->IsFailure()) return result;
reinterpret_cast<PixelArray*>(result)->set_map(pixel_array_map());
reinterpret_cast<PixelArray*>(result)->set_length(length);
reinterpret_cast<PixelArray*>(result)->set_external_pointer(external_pointer);
return result;
}
Object* Heap::AllocateExternalArray(int length,
ExternalArrayType array_type,
void* external_pointer,
PretenureFlag pretenure) {
AllocationSpace space = (pretenure == TENURED) ? OLD_DATA_SPACE : NEW_SPACE;
Object* result = AllocateRaw(ExternalArray::kAlignedSize,
space,
OLD_DATA_SPACE);
if (result->IsFailure()) return result;
reinterpret_cast<ExternalArray*>(result)->set_map(
MapForExternalArrayType(array_type));
reinterpret_cast<ExternalArray*>(result)->set_length(length);
reinterpret_cast<ExternalArray*>(result)->set_external_pointer(
external_pointer);
return result;
}
Object* Heap::CreateCode(const CodeDesc& desc,
Code::Flags flags,
Handle<Object> self_reference) {
// Allocate ByteArray before the Code object, so that we do not risk
// leaving uninitialized Code object (and breaking the heap).
Object* reloc_info = AllocateByteArray(desc.reloc_size, TENURED);
if (reloc_info->IsFailure()) return reloc_info;
// Compute size
int body_size = RoundUp(desc.instr_size, kObjectAlignment);
int obj_size = Code::SizeFor(body_size);
ASSERT(IsAligned(static_cast<intptr_t>(obj_size), kCodeAlignment));
Object* result;
if (obj_size > MaxObjectSizeInPagedSpace()) {
result = lo_space_->AllocateRawCode(obj_size);
} else {
result = code_space_->AllocateRaw(obj_size);
}
if (result->IsFailure()) return result;
// Initialize the object
HeapObject::cast(result)->set_map(code_map());
Code* code = Code::cast(result);
ASSERT(!CodeRange::exists() || CodeRange::contains(code->address()));
code->set_instruction_size(desc.instr_size);
code->set_relocation_info(ByteArray::cast(reloc_info));
code->set_flags(flags);
// Allow self references to created code object by patching the handle to
// point to the newly allocated Code object.
if (!self_reference.is_null()) {
*(self_reference.location()) = code;
}
// Migrate generated code.
// The generated code can contain Object** values (typically from handles)
// that are dereferenced during the copy to point directly to the actual heap
// objects. These pointers can include references to the code object itself,
// through the self_reference parameter.
code->CopyFrom(desc);
#ifdef DEBUG
code->Verify();
#endif
return code;
}
Object* Heap::CopyCode(Code* code) {
// Allocate an object the same size as the code object.
int obj_size = code->Size();
Object* result;
if (obj_size > MaxObjectSizeInPagedSpace()) {
result = lo_space_->AllocateRawCode(obj_size);
} else {
result = code_space_->AllocateRaw(obj_size);
}
if (result->IsFailure()) return result;
// Copy code object.
Address old_addr = code->address();
Address new_addr = reinterpret_cast<HeapObject*>(result)->address();
CopyBlock(new_addr, old_addr, obj_size);
// Relocate the copy.
Code* new_code = Code::cast(result);
ASSERT(!CodeRange::exists() || CodeRange::contains(code->address()));
new_code->Relocate(new_addr - old_addr);
return new_code;
}
Object* Heap::CopyCode(Code* code, Vector<byte> reloc_info) {
// Allocate ByteArray before the Code object, so that we do not risk
// leaving uninitialized Code object (and breaking the heap).
Object* reloc_info_array = AllocateByteArray(reloc_info.length(), TENURED);
if (reloc_info_array->IsFailure()) return reloc_info_array;
int new_body_size = RoundUp(code->instruction_size(), kObjectAlignment);
int new_obj_size = Code::SizeFor(new_body_size);
Address old_addr = code->address();
size_t relocation_offset =
static_cast<size_t>(code->instruction_end() - old_addr);
Object* result;
if (new_obj_size > MaxObjectSizeInPagedSpace()) {
result = lo_space_->AllocateRawCode(new_obj_size);
} else {
result = code_space_->AllocateRaw(new_obj_size);
}
if (result->IsFailure()) return result;
// Copy code object.
Address new_addr = reinterpret_cast<HeapObject*>(result)->address();
// Copy header and instructions.
memcpy(new_addr, old_addr, relocation_offset);
Code* new_code = Code::cast(result);
new_code->set_relocation_info(ByteArray::cast(reloc_info_array));
// Copy patched rinfo.
memcpy(new_code->relocation_start(), reloc_info.start(), reloc_info.length());
// Relocate the copy.
ASSERT(!CodeRange::exists() || CodeRange::contains(code->address()));
new_code->Relocate(new_addr - old_addr);
#ifdef DEBUG
code->Verify();
#endif
return new_code;
}
Object* Heap::Allocate(Map* map, AllocationSpace space) {
ASSERT(gc_state_ == NOT_IN_GC);
ASSERT(map->instance_type() != MAP_TYPE);
// If allocation failures are disallowed, we may allocate in a different
// space when new space is full and the object is not a large object.
AllocationSpace retry_space =
(space != NEW_SPACE) ? space : TargetSpaceId(map->instance_type());
Object* result =
AllocateRaw(map->instance_size(), space, retry_space);
if (result->IsFailure()) return result;
HeapObject::cast(result)->set_map(map);
#ifdef ENABLE_LOGGING_AND_PROFILING
ProducerHeapProfile::RecordJSObjectAllocation(result);
#endif
return result;
}
Object* Heap::InitializeFunction(JSFunction* function,
SharedFunctionInfo* shared,
Object* prototype) {
ASSERT(!prototype->IsMap());
function->initialize_properties();
function->initialize_elements();
function->set_shared(shared);
function->set_code(shared->code());
function->set_prototype_or_initial_map(prototype);
function->set_context(undefined_value());
function->set_literals(empty_fixed_array());
return function;
}
Object* Heap::AllocateFunctionPrototype(JSFunction* function) {
// Allocate the prototype. Make sure to use the object function
// from the function's context, since the function can be from a
// different context.
JSFunction* object_function =
function->context()->global_context()->object_function();
Object* prototype = AllocateJSObject(object_function);
if (prototype->IsFailure()) return prototype;
// When creating the prototype for the function we must set its
// constructor to the function.
Object* result =
JSObject::cast(prototype)->SetProperty(constructor_symbol(),
function,
DONT_ENUM);
if (result->IsFailure()) return result;
return prototype;
}
Object* Heap::AllocateFunction(Map* function_map,
SharedFunctionInfo* shared,
Object* prototype,
PretenureFlag pretenure) {
AllocationSpace space =
(pretenure == TENURED) ? OLD_POINTER_SPACE : NEW_SPACE;
Object* result = Allocate(function_map, space);
if (result->IsFailure()) return result;
return InitializeFunction(JSFunction::cast(result), shared, prototype);
}
Object* Heap::AllocateArgumentsObject(Object* callee, int length) {
// To get fast allocation and map sharing for arguments objects we
// allocate them based on an arguments boilerplate.
// This calls Copy directly rather than using Heap::AllocateRaw so we
// duplicate the check here.
ASSERT(allocation_allowed_ && gc_state_ == NOT_IN_GC);
JSObject* boilerplate =
Top::context()->global_context()->arguments_boilerplate();
// Check that the size of the boilerplate matches our
// expectations. The ArgumentsAccessStub::GenerateNewObject relies
// on the size being a known constant.
ASSERT(kArgumentsObjectSize == boilerplate->map()->instance_size());
// Do the allocation.
Object* result =
AllocateRaw(kArgumentsObjectSize, NEW_SPACE, OLD_POINTER_SPACE);
if (result->IsFailure()) return result;
// Copy the content. The arguments boilerplate doesn't have any
// fields that point to new space so it's safe to skip the write
// barrier here.
CopyBlock(HeapObject::cast(result)->address(),
boilerplate->address(),
kArgumentsObjectSize);
// Set the two properties.
JSObject::cast(result)->InObjectPropertyAtPut(arguments_callee_index,
callee);
JSObject::cast(result)->InObjectPropertyAtPut(arguments_length_index,
Smi::FromInt(length),
SKIP_WRITE_BARRIER);
// Check the state of the object
ASSERT(JSObject::cast(result)->HasFastProperties());
ASSERT(JSObject::cast(result)->HasFastElements());
return result;
}
static bool HasDuplicates(DescriptorArray* descriptors) {
int count = descriptors->number_of_descriptors();
if (count > 1) {
String* prev_key = descriptors->GetKey(0);
for (int i = 1; i != count; i++) {
String* current_key = descriptors->GetKey(i);
if (prev_key == current_key) return true;
prev_key = current_key;
}
}
return false;
}
Object* Heap::AllocateInitialMap(JSFunction* fun) {
ASSERT(!fun->has_initial_map());
// First create a new map with the size and number of in-object properties
// suggested by the function.
int instance_size = fun->shared()->CalculateInstanceSize();
int in_object_properties = fun->shared()->CalculateInObjectProperties();
Object* map_obj = Heap::AllocateMap(JS_OBJECT_TYPE, instance_size);
if (map_obj->IsFailure()) return map_obj;
// Fetch or allocate prototype.
Object* prototype;
if (fun->has_instance_prototype()) {
prototype = fun->instance_prototype();
} else {
prototype = AllocateFunctionPrototype(fun);
if (prototype->IsFailure()) return prototype;
}
Map* map = Map::cast(map_obj);
map->set_inobject_properties(in_object_properties);
map->set_unused_property_fields(in_object_properties);
map->set_prototype(prototype);
ASSERT(map->has_fast_elements());
// If the function has only simple this property assignments add
// field descriptors for these to the initial map as the object
// cannot be constructed without having these properties. Guard by
// the inline_new flag so we only change the map if we generate a
// specialized construct stub.
ASSERT(in_object_properties <= Map::kMaxPreAllocatedPropertyFields);
if (fun->shared()->CanGenerateInlineConstructor(prototype)) {
int count = fun->shared()->this_property_assignments_count();
if (count > in_object_properties) {
// Inline constructor can only handle inobject properties.
fun->shared()->ForbidInlineConstructor();
} else {
Object* descriptors_obj = DescriptorArray::Allocate(count);
if (descriptors_obj->IsFailure()) return descriptors_obj;
DescriptorArray* descriptors = DescriptorArray::cast(descriptors_obj);
for (int i = 0; i < count; i++) {
String* name = fun->shared()->GetThisPropertyAssignmentName(i);
ASSERT(name->IsSymbol());
FieldDescriptor field(name, i, NONE);
field.SetEnumerationIndex(i);
descriptors->Set(i, &field);
}
descriptors->SetNextEnumerationIndex(count);
descriptors->SortUnchecked();
// The descriptors may contain duplicates because the compiler does not
// guarantee the uniqueness of property names (it would have required
// quadratic time). Once the descriptors are sorted we can check for
// duplicates in linear time.
if (HasDuplicates(descriptors)) {
fun->shared()->ForbidInlineConstructor();
} else {
map->set_instance_descriptors(descriptors);
map->set_pre_allocated_property_fields(count);
map->set_unused_property_fields(in_object_properties - count);
}
}
}
fun->shared()->StartInobjectSlackTracking(map);
return map;
}
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 (eg, Smi::FromInt(0)) and the elements initialized to a
// fixed array (eg, Heap::empty_fixed_array()). Currently, the object
// verification code has to cope with (temporarily) invalid objects. See
// for example, JSArray::JSArrayVerify).
Object* filler;
// 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.
if (map->constructor()->IsJSFunction() &&
JSFunction::cast(map->constructor())->shared()->
IsInobjectSlackTrackingInProgress()) {
// We might want to shrink the object later.
ASSERT(obj->GetInternalFieldCount() == 0);
filler = Heap::one_pointer_filler_map();
} else {
filler = Heap::undefined_value();
}
obj->InitializeBody(map->instance_size(), filler);
}
Object* Heap::AllocateJSObjectFromMap(Map* map, PretenureFlag pretenure) {
// JSFunctions should be allocated using AllocateFunction to be
// properly initialized.
ASSERT(map->instance_type() != JS_FUNCTION_TYPE);
// Both types of global objects should be allocated using
// AllocateGlobalObject to be properly initialized.
ASSERT(map->instance_type() != JS_GLOBAL_OBJECT_TYPE);
ASSERT(map->instance_type() != JS_BUILTINS_OBJECT_TYPE);
// Allocate the backing storage for the properties.
int prop_size =
map->pre_allocated_property_fields() +
map->unused_property_fields() -
map->inobject_properties();
ASSERT(prop_size >= 0);
Object* properties = AllocateFixedArray(prop_size, pretenure);
if (properties->IsFailure()) return properties;
// Allocate the JSObject.
AllocationSpace space =
(pretenure == TENURED) ? OLD_POINTER_SPACE : NEW_SPACE;
if (map->instance_size() > MaxObjectSizeInPagedSpace()) space = LO_SPACE;
Object* obj = Allocate(map, space);
if (obj->IsFailure()) return obj;
// Initialize the JSObject.
InitializeJSObjectFromMap(JSObject::cast(obj),
FixedArray::cast(properties),
map);
ASSERT(JSObject::cast(obj)->HasFastElements());
return obj;
}
Object* Heap::AllocateJSObject(JSFunction* constructor,
PretenureFlag pretenure) {
// Allocate the initial map if absent.
if (!constructor->has_initial_map()) {
Object* initial_map = AllocateInitialMap(constructor);
if (initial_map->IsFailure()) return initial_map;
constructor->set_initial_map(Map::cast(initial_map));
Map::cast(initial_map)->set_constructor(constructor);
}
// Allocate the object based on the constructors initial map.
Object* result =
AllocateJSObjectFromMap(constructor->initial_map(), pretenure);
// Make sure result is NOT a global object if valid.
ASSERT(result->IsFailure() || !result->IsGlobalObject());
return result;
}
Object* Heap::AllocateGlobalObject(JSFunction* constructor) {
ASSERT(constructor->has_initial_map());
Map* map = constructor->initial_map();
// Make sure no field properties are described in the initial map.
// This guarantees us that normalizing the properties does not
// require us to change property values to JSGlobalPropertyCells.
ASSERT(map->NextFreePropertyIndex() == 0);
// Make sure we don't have a ton of pre-allocated slots in the
// global objects. They will be unused once we normalize the object.
ASSERT(map->unused_property_fields() == 0);
ASSERT(map->inobject_properties() == 0);
// Initial size of the backing store to avoid resize of the storage during
// bootstrapping. The size differs between the JS global object ad the
// builtins object.
int initial_size = map->instance_type() == JS_GLOBAL_OBJECT_TYPE ? 64 : 512;
// Allocate a dictionary object for backing storage.
Object* obj =
StringDictionary::Allocate(
map->NumberOfDescribedProperties() * 2 + initial_size);
if (obj->IsFailure()) return obj;
StringDictionary* dictionary = StringDictionary::cast(obj);
// The global object might be created from an object template with accessors.
// Fill these accessors into the dictionary.
DescriptorArray* descs = map->instance_descriptors();
for (int i = 0; i < descs->number_of_descriptors(); i++) {
PropertyDetails details = descs->GetDetails(i);
ASSERT(details.type() == CALLBACKS); // Only accessors are expected.
PropertyDetails d =
PropertyDetails(details.attributes(), CALLBACKS, details.index());
Object* value = descs->GetCallbacksObject(i);
value = Heap::AllocateJSGlobalPropertyCell(value);
if (value->IsFailure()) return value;
Object* result = dictionary->Add(descs->GetKey(i), value, d);
if (result->IsFailure()) return result;
dictionary = StringDictionary::cast(result);
}
// Allocate the global object and initialize it with the backing store.
obj = Allocate(map, OLD_POINTER_SPACE);
if (obj->IsFailure()) return obj;
JSObject* global = JSObject::cast(obj);
InitializeJSObjectFromMap(global, dictionary, map);
// Create a new map for the global object.
obj = map->CopyDropDescriptors();
if (obj->IsFailure()) return obj;
Map* new_map = Map::cast(obj);
// Setup the global object as a normalized object.
global->set_map(new_map);
global->map()->set_instance_descriptors(Heap::empty_descriptor_array());
global->set_properties(dictionary);
// Make sure result is a global object with properties in dictionary.
ASSERT(global->IsGlobalObject());
ASSERT(!global->HasFastProperties());
return global;
}
Object* Heap::CopyJSObject(JSObject* source) {
// Never used to copy functions. If functions need to be copied we
// have to be careful to clear the literals array.
ASSERT(!source->IsJSFunction());
// Make the clone.
Map* map = source->map();
int object_size = map->instance_size();
Object* clone;
// If we're forced to always allocate, we use the general allocation
// functions which may leave us with an object in old space.
if (always_allocate()) {
clone = AllocateRaw(object_size, NEW_SPACE, OLD_POINTER_SPACE);
if (clone->IsFailure()) return clone;
Address clone_address = HeapObject::cast(clone)->address();
CopyBlock(clone_address,
source->address(),
object_size);
// Update write barrier for all fields that lie beyond the header.
RecordWrites(clone_address,
JSObject::kHeaderSize,
(object_size - JSObject::kHeaderSize) / kPointerSize);
} else {
clone = new_space_.AllocateRaw(object_size);
if (clone->IsFailure()) return clone;
ASSERT(Heap::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(HeapObject::cast(clone)->address(),
source->address(),
object_size);
}
FixedArray* elements = FixedArray::cast(source->elements());
FixedArray* properties = FixedArray::cast(source->properties());
// Update elements if necessary.
if (elements->length() > 0) {
Object* elem =
(elements->map() == fixed_cow_array_map()) ?
elements : CopyFixedArray(elements);
if (elem->IsFailure()) return elem;
JSObject::cast(clone)->set_elements(FixedArray::cast(elem));
}
// Update properties if necessary.
if (properties->length() > 0) {
Object* prop = CopyFixedArray(properties);
if (prop->IsFailure()) return prop;
JSObject::cast(clone)->set_properties(FixedArray::cast(prop));
}
// Return the new clone.
#ifdef ENABLE_LOGGING_AND_PROFILING
ProducerHeapProfile::RecordJSObjectAllocation(clone);
#endif
return clone;
}
Object* Heap::ReinitializeJSGlobalProxy(JSFunction* constructor,
JSGlobalProxy* object) {
ASSERT(constructor->has_initial_map());
Map* map = constructor->initial_map();
// Check that the already allocated object has the same size and type as
// objects allocated using the constructor.
ASSERT(map->instance_size() == object->map()->instance_size());
ASSERT(map->instance_type() == object->map()->instance_type());
// Allocate the backing storage for the properties.
int prop_size = map->unused_property_fields() - map->inobject_properties();
Object* properties = AllocateFixedArray(prop_size, TENURED);
if (properties->IsFailure()) return properties;
// Reset the map for the object.
object->set_map(constructor->initial_map());
// Reinitialize the object from the constructor map.
InitializeJSObjectFromMap(object, FixedArray::cast(properties), map);
return object;
}
Object* Heap::AllocateStringFromAscii(Vector<const char> string,
PretenureFlag pretenure) {
Object* result = AllocateRawAsciiString(string.length(), pretenure);
if (result->IsFailure()) return result;
// Copy the characters into the new object.
SeqAsciiString* string_result = SeqAsciiString::cast(result);
for (int i = 0; i < string.length(); i++) {
string_result->SeqAsciiStringSet(i, string[i]);
}
return result;
}
Object* Heap::AllocateStringFromUtf8(Vector<const char> string,
PretenureFlag pretenure) {
// V8 only supports characters in the Basic Multilingual Plane.
const uc32 kMaxSupportedChar = 0xFFFF;
// Count the number of characters in the UTF-8 string and check if
// it is an ASCII string.
Access<Scanner::Utf8Decoder> decoder(Scanner::utf8_decoder());
decoder->Reset(string.start(), string.length());
int chars = 0;
bool is_ascii = true;
while (decoder->has_more()) {
uc32 r = decoder->GetNext();
if (r > String::kMaxAsciiCharCode) is_ascii = false;
chars++;
}
// If the string is ascii, we do not need to convert the characters
// since UTF8 is backwards compatible with ascii.
if (is_ascii) return AllocateStringFromAscii(string, pretenure);
Object* result = AllocateRawTwoByteString(chars, pretenure);
if (result->IsFailure()) return result;
// Convert and copy the characters into the new object.
String* string_result = String::cast(result);
decoder->Reset(string.start(), string.length());
for (int i = 0; i < chars; i++) {
uc32 r = decoder->GetNext();
if (r > kMaxSupportedChar) { r = unibrow::Utf8::kBadChar; }
string_result->Set(i, r);
}
return result;
}
Object* Heap::AllocateStringFromTwoByte(Vector<const uc16> string,
PretenureFlag pretenure) {
// Check if the string is an ASCII string.
int i = 0;
while (i < string.length() && string[i] <= String::kMaxAsciiCharCode) i++;
Object* result;
if (i == string.length()) { // It's an ASCII string.
result = AllocateRawAsciiString(string.length(), pretenure);
} else { // It's not an ASCII string.
result = AllocateRawTwoByteString(string.length(), pretenure);
}
if (result->IsFailure()) return result;
// Copy the characters into the new object, which may be either ASCII or
// UTF-16.
String* string_result = String::cast(result);
for (int i = 0; i < string.length(); i++) {
string_result->Set(i, string[i]);
}
return result;
}
Map* Heap::SymbolMapForString(String* string) {
// If the string is in new space it cannot be used as a symbol.
if (InNewSpace(string)) return NULL;
// Find the corresponding symbol map for strings.
Map* map = string->map();
if (map == ascii_string_map()) return ascii_symbol_map();
if (map == string_map()) return symbol_map();
if (map == cons_string_map()) return cons_symbol_map();
if (map == cons_ascii_string_map()) return cons_ascii_symbol_map();
if (map == external_string_map()) return external_symbol_map();
if (map == external_ascii_string_map()) return external_ascii_symbol_map();
if (map == external_string_with_ascii_data_map()) {
return external_symbol_with_ascii_data_map();
}
// No match found.
return NULL;
}
Object* Heap::AllocateInternalSymbol(unibrow::CharacterStream* buffer,
int chars,
uint32_t hash_field) {
ASSERT(chars >= 0);
// Ensure the chars matches the number of characters in the buffer.
ASSERT(static_cast<unsigned>(chars) == buffer->Length());
// Determine whether the string is ascii.
bool is_ascii = true;
while (buffer->has_more()) {
if (buffer->GetNext() > unibrow::Utf8::kMaxOneByteChar) {
is_ascii = false;
break;
}
}
buffer->Rewind();
// Compute map and object size.
int size;
Map* map;
if (is_ascii) {
if (chars > SeqAsciiString::kMaxLength) {
return Failure::OutOfMemoryException();
}
map = ascii_symbol_map();
size = SeqAsciiString::SizeFor(chars);
} else {
if (chars > SeqTwoByteString::kMaxLength) {
return Failure::OutOfMemoryException();
}
map = symbol_map();
size = SeqTwoByteString::SizeFor(chars);
}
// Allocate string.
Object* result = (size > MaxObjectSizeInPagedSpace())
? lo_space_->AllocateRaw(size)
: old_data_space_->AllocateRaw(size);
if (result->IsFailure()) return result;
reinterpret_cast<HeapObject*>(result)->set_map(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);
ASSERT_EQ(size, answer->Size());
// Fill in the characters.
for (int i = 0; i < chars; i++) {
answer->Set(i, buffer->GetNext());
}
return answer;
}
Object* Heap::AllocateRawAsciiString(int length, PretenureFlag pretenure) {
if (length < 0 || length > SeqAsciiString::kMaxLength) {
return Failure::OutOfMemoryException();
}
int size = SeqAsciiString::SizeFor(length);
ASSERT(size <= SeqAsciiString::kMaxSize);
AllocationSpace space = (pretenure == TENURED) ? OLD_DATA_SPACE : NEW_SPACE;
AllocationSpace retry_space = OLD_DATA_SPACE;
if (space == NEW_SPACE) {
if (size > kMaxObjectSizeInNewSpace) {
// Allocate in large object space, retry space will be ignored.
space = LO_SPACE;
} else if (size > MaxObjectSizeInPagedSpace()) {
// Allocate in new space, retry in large object space.
retry_space = LO_SPACE;
}
} else if (space == OLD_DATA_SPACE && size > MaxObjectSizeInPagedSpace()) {
space = LO_SPACE;
}
Object* result = AllocateRaw(size, space, retry_space);
if (result->IsFailure()) return result;
// Partially initialize the object.
HeapObject::cast(result)->set_map(ascii_string_map());
String::cast(result)->set_length(length);
String::cast(result)->set_hash_field(String::kEmptyHashField);
ASSERT_EQ(size, HeapObject::cast(result)->Size());
return result;
}
Object* Heap::AllocateRawTwoByteString(int length, PretenureFlag pretenure) {
if (length < 0 || length > SeqTwoByteString::kMaxLength) {
return Failure::OutOfMemoryException();
}
int size = SeqTwoByteString::SizeFor(length);
ASSERT(size <= SeqTwoByteString::kMaxSize);
AllocationSpace space = (pretenure == TENURED) ? OLD_DATA_SPACE : NEW_SPACE;
AllocationSpace retry_space = OLD_DATA_SPACE;
if (space == NEW_SPACE) {
if (size > kMaxObjectSizeInNewSpace) {
// Allocate in large object space, retry space will be ignored.
space = LO_SPACE;
} else if (size > MaxObjectSizeInPagedSpace()) {
// Allocate in new space, retry in large object space.
retry_space = LO_SPACE;
}
} else if (space == OLD_DATA_SPACE && size > MaxObjectSizeInPagedSpace()) {
space = LO_SPACE;
}
Object* result = AllocateRaw(size, space, retry_space);
if (result->IsFailure()) return result;
// Partially initialize the object.
HeapObject::cast(result)->set_map(string_map());
String::cast(result)->set_length(length);
String::cast(result)->set_hash_field(String::kEmptyHashField);
ASSERT_EQ(size, HeapObject::cast(result)->Size());
return result;
}
Object* Heap::AllocateEmptyFixedArray() {
int size = FixedArray::SizeFor(0);
Object* result = AllocateRaw(size, OLD_DATA_SPACE, OLD_DATA_SPACE);
if (result->IsFailure()) return result;
// Initialize the object.
reinterpret_cast<FixedArray*>(result)->set_map(fixed_array_map());
reinterpret_cast<FixedArray*>(result)->set_length(0);
return result;
}
Object* Heap::AllocateRawFixedArray(int length) {
if (length < 0 || length > FixedArray::kMaxLength) {
return Failure::OutOfMemoryException();
}
ASSERT(length > 0);
// Use the general function if we're forced to always allocate.
if (always_allocate()) return AllocateFixedArray(length, TENURED);
// Allocate the raw data for a fixed array.
int size = FixedArray::SizeFor(length);
return size <= kMaxObjectSizeInNewSpace
? new_space_.AllocateRaw(size)
: lo_space_->AllocateRawFixedArray(size);
}
Object* Heap::CopyFixedArrayWithMap(FixedArray* src, Map* map) {
int len = src->length();
Object* obj = AllocateRawFixedArray(len);
if (obj->IsFailure()) return obj;
if (Heap::InNewSpace(obj)) {
HeapObject* dst = HeapObject::cast(obj);
dst->set_map(map);
CopyBlock(dst->address() + kPointerSize,
src->address() + kPointerSize,
FixedArray::SizeFor(len) - kPointerSize);
return obj;
}
HeapObject::cast(obj)->set_map(map);
FixedArray* result = FixedArray::cast(obj);
result->set_length(len);
// Copy the content
AssertNoAllocation no_gc;
WriteBarrierMode mode = result->GetWriteBarrierMode(no_gc);
for (int i = 0; i < len; i++) result->set(i, src->get(i), mode);
return result;
}
Object* Heap::AllocateFixedArray(int length) {
ASSERT(length >= 0);
if (length == 0) return empty_fixed_array();
Object* result = AllocateRawFixedArray(length);
if (!result->IsFailure()) {
// Initialize header.
FixedArray* array = reinterpret_cast<FixedArray*>(result);
array->set_map(fixed_array_map());
array->set_length(length);
// Initialize body.
ASSERT(!Heap::InNewSpace(undefined_value()));
MemsetPointer(array->data_start(), undefined_value(), length);
}
return result;
}
Object* Heap::AllocateRawFixedArray(int length, PretenureFlag pretenure) {
if (length < 0 || length > FixedArray::kMaxLength) {
return Failure::OutOfMemoryException();
}
AllocationSpace space =
(pretenure == TENURED) ? OLD_POINTER_SPACE : NEW_SPACE;
int size = FixedArray::SizeFor(length);
if (space == NEW_SPACE && size > kMaxObjectSizeInNewSpace) {
// Too big for new space.
space = LO_SPACE;
} else if (space == OLD_POINTER_SPACE &&
size > MaxObjectSizeInPagedSpace()) {
// Too big for old pointer space.
space = LO_SPACE;
}
AllocationSpace retry_space =
(size <= MaxObjectSizeInPagedSpace()) ? OLD_POINTER_SPACE : LO_SPACE;
return AllocateRaw(size, space, retry_space);
}
static Object* AllocateFixedArrayWithFiller(int length,
PretenureFlag pretenure,
Object* filler) {
ASSERT(length >= 0);
ASSERT(Heap::empty_fixed_array()->IsFixedArray());
if (length == 0) return Heap::empty_fixed_array();
ASSERT(!Heap::InNewSpace(filler));
Object* result = Heap::AllocateRawFixedArray(length, pretenure);
if (result->IsFailure()) return result;
HeapObject::cast(result)->set_map(Heap::fixed_array_map());
FixedArray* array = FixedArray::cast(result);
array->set_length(length);
MemsetPointer(array->data_start(), filler, length);
return array;
}
Object* Heap::AllocateFixedArray(int length, PretenureFlag pretenure) {
return AllocateFixedArrayWithFiller(length, pretenure, undefined_value());
}
Object* Heap::AllocateFixedArrayWithHoles(int length, PretenureFlag pretenure) {
return AllocateFixedArrayWithFiller(length, pretenure, the_hole_value());
}
Object* Heap::AllocateUninitializedFixedArray(int length) {
if (length == 0) return empty_fixed_array();
Object* obj = AllocateRawFixedArray(length);
if (obj->IsFailure()) return obj;
reinterpret_cast<FixedArray*>(obj)->set_map(fixed_array_map());
FixedArray::cast(obj)->set_length(length);
return obj;
}
Object* Heap::AllocateHashTable(int length, PretenureFlag pretenure) {
Object* result = Heap::AllocateFixedArray(length, pretenure);
if (result->IsFailure()) return result;
reinterpret_cast<HeapObject*>(result)->set_map(hash_table_map());
ASSERT(result->IsHashTable());
return result;
}
Object* Heap::AllocateGlobalContext() {
Object* result = Heap::AllocateFixedArray(Context::GLOBAL_CONTEXT_SLOTS);
if (result->IsFailure()) return result;
Context* context = reinterpret_cast<Context*>(result);
context->set_map(global_context_map());
ASSERT(context->IsGlobalContext());
ASSERT(result->IsContext());
return result;
}
Object* Heap::AllocateFunctionContext(int length, JSFunction* function) {
ASSERT(length >= Context::MIN_CONTEXT_SLOTS);
Object* result = Heap::AllocateFixedArray(length);
if (result->IsFailure()) return result;
Context* context = reinterpret_cast<Context*>(result);
context->set_map(context_map());
context->set_closure(function);
context->set_fcontext(context);
context->set_previous(NULL);
context->set_extension(NULL);
context->set_global(function->context()->global());
ASSERT(!context->IsGlobalContext());
ASSERT(context->is_function_context());
ASSERT(result->IsContext());
return result;
}
Object* Heap::AllocateWithContext(Context* previous,
JSObject* extension,
bool is_catch_context) {
Object* result = Heap::AllocateFixedArray(Context::MIN_CONTEXT_SLOTS);
if (result->IsFailure()) return result;
Context* context = reinterpret_cast<Context*>(result);
context->set_map(is_catch_context ? catch_context_map() : context_map());
context->set_closure(previous->closure());
context->set_fcontext(previous->fcontext());
context->set_previous(previous);
context->set_extension(extension);
context->set_global(previous->global());
ASSERT(!context->IsGlobalContext());
ASSERT(!context->is_function_context());
ASSERT(result->IsContext());
return result;
}
Object* 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 Failure::InternalError();
}
int size = map->instance_size();
AllocationSpace space =
(size > MaxObjectSizeInPagedSpace()) ? LO_SPACE : OLD_POINTER_SPACE;
Object* result = Heap::Allocate(map, space);
if (result->IsFailure()) return result;
Struct::cast(result)->InitializeBody(size);
return result;
}
bool Heap::IdleNotification() {
static const int kIdlesBeforeScavenge = 4;
static const int kIdlesBeforeMarkSweep = 7;
static const int kIdlesBeforeMarkCompact = 8;
static int number_idle_notifications = 0;
static int last_gc_count = gc_count_;
bool uncommit = true;
bool finished = false;
if (last_gc_count == gc_count_) {
number_idle_notifications++;
} else {
number_idle_notifications = 0;
last_gc_count = gc_count_;
}
if (number_idle_notifications == kIdlesBeforeScavenge) {
if (contexts_disposed_ > 0) {
HistogramTimerScope scope(&Counters::gc_context);
CollectAllGarbage(false);
} else {
CollectGarbage(0, NEW_SPACE);
}
new_space_.Shrink();
last_gc_count = gc_count_;
} else if (number_idle_notifications == kIdlesBeforeMarkSweep) {
// Before doing the mark-sweep collections we clear the
// compilation cache to avoid hanging on to source code and
// generated code for cached functions.
CompilationCache::Clear();
CollectAllGarbage(false);
new_space_.Shrink();
last_gc_count = gc_count_;
} else if (number_idle_notifications == kIdlesBeforeMarkCompact) {
CollectAllGarbage(true);
new_space_.Shrink();
last_gc_count = gc_count_;
number_idle_notifications = 0;
finished = true;
} else if (contexts_disposed_ > 0) {
if (FLAG_expose_gc) {
contexts_disposed_ = 0;
} else {
HistogramTimerScope scope(&Counters::gc_context);
CollectAllGarbage(false);
last_gc_count = gc_count_;
}
// If this is the first idle notification, we reset the
// notification count to avoid letting idle notifications for
// context disposal garbage collections start a potentially too
// aggressive idle GC cycle.
if (number_idle_notifications <= 1) {
number_idle_notifications = 0;
uncommit = false;
}
}
// Make sure that we have no pending context disposals and
// conditionally uncommit from space.
ASSERT(contexts_disposed_ == 0);
if (uncommit) Heap::UncommitFromSpace();
return finished;
}
#ifdef DEBUG
void Heap::Print() {
if (!HasBeenSetup()) return;
Top::PrintStack();
AllSpaces spaces;
for (Space* space = spaces.next(); space != NULL; space = spaces.next())
space->Print();
}
void Heap::ReportCodeStatistics(const char* title) {
PrintF(">>>>>> Code Stats (%s) >>>>>>\n", title);
PagedSpace::ResetCodeStatistics();
// We do not look for code in new space, map space, or old space. If code
// somehow ends up in those spaces, we would miss it here.
code_space_->CollectCodeStatistics();
lo_space_->CollectCodeStatistics();
PagedSpace::ReportCodeStatistics();
}
// 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("mark-compact GC : %d\n", mc_count_);
PrintF("old_gen_promotion_limit_ %d\n", old_gen_promotion_limit_);
PrintF("old_gen_allocation_limit_ %d\n", old_gen_allocation_limit_);
PrintF("\n");
PrintF("Number of handles : %d\n", HandleScope::NumberOfHandles());
GlobalHandles::PrintStats();
PrintF("\n");
PrintF("Heap statistics : ");
MemoryAllocator::ReportStatistics();
PrintF("To space : ");
new_space_.ReportStatistics();
PrintF("Old pointer space : ");
old_pointer_space_->ReportStatistics();
PrintF("Old data space : ");
old_data_space_->ReportStatistics();
PrintF("Code space : ");
code_space_->ReportStatistics();
PrintF("Map space : ");
map_space_->ReportStatistics();
PrintF("Cell space : ");
cell_space_->ReportStatistics();
PrintF("Large object space : ");
lo_space_->ReportStatistics();
PrintF(">>>>>> ========================================= >>>>>>\n");
}
#endif // DEBUG
bool Heap::Contains(HeapObject* value) {
return Contains(value->address());
}
bool Heap::Contains(Address addr) {
if (OS::IsOutsideAllocatedSpace(addr)) return false;
return HasBeenSetup() &&
(new_space_.ToSpaceContains(addr) ||
old_pointer_space_->Contains(addr) ||
old_data_space_->Contains(addr) ||
code_space_->Contains(addr) ||
map_space_->Contains(addr) ||
cell_space_->Contains(addr) ||
lo_space_->SlowContains(addr));
}
bool Heap::InSpace(HeapObject* value, AllocationSpace space) {
return InSpace(value->address(), space);
}
bool Heap::InSpace(Address addr, AllocationSpace space) {
if (OS::IsOutsideAllocatedSpace(addr)) return false;
if (!HasBeenSetup()) return false;
switch (space) {
case NEW_SPACE:
return new_space_.ToSpaceContains(addr);
case OLD_POINTER_SPACE:
return old_pointer_space_->Contains(addr);
case OLD_DATA_SPACE:
return old_data_space_->Contains(addr);
case CODE_SPACE:
return code_space_->Contains(addr);
case MAP_SPACE:
return map_space_->Contains(addr);
case CELL_SPACE:
return cell_space_->Contains(addr);
case LO_SPACE:
return lo_space_->SlowContains(addr);
}
return false;
}
#ifdef DEBUG
static void DummyScavengePointer(HeapObject** p) {
}
static void VerifyPointersUnderWatermark(
PagedSpace* space,
DirtyRegionCallback visit_dirty_region) {
PageIterator it(space, PageIterator::PAGES_IN_USE);
while (it.has_next()) {
Page* page = it.next();
Address start = page->ObjectAreaStart();
Address end = page->AllocationWatermark();
Heap::IterateDirtyRegions(Page::kAllRegionsDirtyMarks,
start,
end,
visit_dirty_region,
&DummyScavengePointer);
}
}
static void VerifyPointersUnderWatermark(LargeObjectSpace* space) {
LargeObjectIterator it(space);
for (HeapObject* object = it.next(); object != NULL; object = it.next()) {
if (object->IsFixedArray()) {
Address slot_address = object->address();
Address end = object->address() + object->Size();
while (slot_address < end) {
HeapObject** slot = reinterpret_cast<HeapObject**>(slot_address);
// When we are not in GC the Heap::InNewSpace() predicate
// checks that pointers which satisfy predicate point into
// the active semispace.
Heap::InNewSpace(*slot);
slot_address += kPointerSize;
}
}
}
}
void Heap::Verify() {
ASSERT(HasBeenSetup());
VerifyPointersVisitor visitor;
IterateRoots(&visitor, VISIT_ONLY_STRONG);
new_space_.Verify();
VerifyPointersAndDirtyRegionsVisitor dirty_regions_visitor;
old_pointer_space_->Verify(&dirty_regions_visitor);
map_space_->Verify(&dirty_regions_visitor);
VerifyPointersUnderWatermark(old_pointer_space_,
&IteratePointersInDirtyRegion);
VerifyPointersUnderWatermark(map_space_,
&IteratePointersInDirtyMapsRegion);
VerifyPointersUnderWatermark(lo_space_);
VerifyPageWatermarkValidity(old_pointer_space_, ALL_INVALID);
VerifyPageWatermarkValidity(map_space_, ALL_INVALID);
VerifyPointersVisitor no_dirty_regions_visitor;
old_data_space_->Verify(&no_dirty_regions_visitor);
code_space_->Verify(&no_dirty_regions_visitor);
cell_space_->Verify(&no_dirty_regions_visitor);
lo_space_->Verify();
}
#endif // DEBUG
Object* Heap::LookupSymbol(Vector<const char> string) {
Object* symbol = NULL;
Object* new_table = symbol_table()->LookupSymbol(string, &symbol);
if (new_table->IsFailure()) return new_table;
// Can't use set_symbol_table because SymbolTable::cast knows that
// SymbolTable is a singleton and checks for identity.
roots_[kSymbolTableRootIndex] = new_table;
ASSERT(symbol != NULL);
return symbol;
}
Object* Heap::LookupSymbol(String* string) {
if (string->IsSymbol()) return string;
Object* symbol = NULL;
Object* new_table = symbol_table()->LookupString(string, &symbol);
if (new_table->IsFailure()) return new_table;
// Can't use set_symbol_table because SymbolTable::cast knows that
// SymbolTable is a singleton and checks for identity.
roots_[kSymbolTableRootIndex] = new_table;
ASSERT(symbol != NULL);
return symbol;
}
bool Heap::LookupSymbolIfExists(String* string, String** symbol) {
if (string->IsSymbol()) {
*symbol = string;
return true;
}
return symbol_table()->LookupSymbolIfExists(string, symbol);
}
#ifdef DEBUG
void Heap::ZapFromSpace() {
ASSERT(reinterpret_cast<Object*>(kFromSpaceZapValue)->IsHeapObject());
for (Address a = new_space_.FromSpaceLow();
a < new_space_.FromSpaceHigh();
a += kPointerSize) {
Memory::Address_at(a) = kFromSpaceZapValue;
}
}
#endif // DEBUG
bool Heap::IteratePointersInDirtyRegion(Address start,
Address end,
ObjectSlotCallback copy_object_func) {
Address slot_address = start;
bool pointers_to_new_space_found = false;
while (slot_address < end) {
Object** slot = reinterpret_cast<Object**>(slot_address);
if (Heap::InNewSpace(*slot)) {
ASSERT((*slot)->IsHeapObject());
copy_object_func(reinterpret_cast<HeapObject**>(slot));
if (Heap::InNewSpace(*slot)) {
ASSERT((*slot)->IsHeapObject());
pointers_to_new_space_found = true;
}
}
slot_address += kPointerSize;
}
return pointers_to_new_space_found;
}
// Compute start address of the first map following given addr.
static inline Address MapStartAlign(Address addr) {
Address page = Page::FromAddress(addr)->ObjectAreaStart();
return page + (((addr - page) + (Map::kSize - 1)) / Map::kSize * Map::kSize);
}
// Compute end address of the first map preceding given addr.
static inline Address MapEndAlign(Address addr) {
Address page = Page::FromAllocationTop(addr)->ObjectAreaStart();
return page + ((addr - page) / Map::kSize * Map::kSize);
}
static bool IteratePointersInDirtyMaps(Address start,
Address end,
ObjectSlotCallback copy_object_func) {
ASSERT(MapStartAlign(start) == start);
ASSERT(MapEndAlign(end) == end);
Address map_address = start;
bool pointers_to_new_space_found = false;
while (map_address < end) {
ASSERT(!Heap::InNewSpace(Memory::Object_at(map_address)));
ASSERT(Memory::Object_at(map_address)->IsMap());
Address pointer_fields_start = map_address + Map::kPointerFieldsBeginOffset;
Address pointer_fields_end = map_address + Map::kPointerFieldsEndOffset;
if (Heap::IteratePointersInDirtyRegion(pointer_fields_start,
pointer_fields_end,
copy_object_func)) {
pointers_to_new_space_found = true;
}
map_address += Map::kSize;
}
return pointers_to_new_space_found;
}
bool Heap::IteratePointersInDirtyMapsRegion(
Address start,
Address end,
ObjectSlotCallback copy_object_func) {
Address map_aligned_start = MapStartAlign(start);
Address map_aligned_end = MapEndAlign(end);
bool contains_pointers_to_new_space = false;
if (map_aligned_start != start) {
Address prev_map = map_aligned_start - Map::kSize;
ASSERT(Memory::Object_at(prev_map)->IsMap());
Address pointer_fields_start =
Max(start, prev_map + Map::kPointerFieldsBeginOffset);
Address pointer_fields_end =
Min(prev_map + Map::kPointerFieldsEndOffset, end);
contains_pointers_to_new_space =
IteratePointersInDirtyRegion(pointer_fields_start,
pointer_fields_end,
copy_object_func)
|| contains_pointers_to_new_space;
}
contains_pointers_to_new_space =
IteratePointersInDirtyMaps(map_aligned_start,
map_aligned_end,
copy_object_func)
|| contains_pointers_to_new_space;
if (map_aligned_end != end) {
ASSERT(Memory::Object_at(map_aligned_end)->IsMap());
Address pointer_fields_start =
map_aligned_end + Map::kPointerFieldsBeginOffset;
Address pointer_fields_end =
Min(end, map_aligned_end + Map::kPointerFieldsEndOffset);
contains_pointers_to_new_space =
IteratePointersInDirtyRegion(pointer_fields_start,
pointer_fields_end,
copy_object_func)
|| contains_pointers_to_new_space;
}
return contains_pointers_to_new_space;
}
void Heap::IterateAndMarkPointersToFromSpace(Address start,
Address end,
ObjectSlotCallback callback) {
Address slot_address = start;
Page* page = Page::FromAddress(start);
uint32_t marks = page->GetRegionMarks();
while (slot_address < end) {
Object** slot = reinterpret_cast<Object**>(slot_address);
if (Heap::InFromSpace(*slot)) {
ASSERT((*slot)->IsHeapObject());
callback(reinterpret_cast<HeapObject**>(slot));
if (Heap::InNewSpace(*slot)) {
ASSERT((*slot)->IsHeapObject());
marks |= page->GetRegionMaskForAddress(slot_address);
}
}
slot_address += kPointerSize;
}
page->SetRegionMarks(marks);
}
uint32_t Heap::IterateDirtyRegions(
uint32_t marks,
Address area_start,
Address area_end,
DirtyRegionCallback visit_dirty_region,
ObjectSlotCallback copy_object_func) {
uint32_t newmarks = 0;
uint32_t mask = 1;
if (area_start >= area_end) {
return newmarks;
}
Address region_start = area_start;
// area_start does not necessarily coincide with start of the first region.
// Thus to calculate the beginning of the next region we have to align
// area_start by Page::kRegionSize.
Address second_region =
reinterpret_cast<Address>(
reinterpret_cast<intptr_t>(area_start + Page::kRegionSize) &
~Page::kRegionAlignmentMask);
// Next region might be beyond area_end.
Address region_end = Min(second_region, area_end);
if (marks & mask) {
if (visit_dirty_region(region_start, region_end, copy_object_func)) {
newmarks |= mask;
}
}
mask <<= 1;
// Iterate subsequent regions which fully lay inside [area_start, area_end[.
region_start = region_end;
region_end = region_start + Page::kRegionSize;
while (region_end <= area_end) {
if (marks & mask) {
if (visit_dirty_region(region_start, region_end, copy_object_func)) {
newmarks |= mask;
}
}
region_start = region_end;
region_end = region_start + Page::kRegionSize;
mask <<= 1;
}
if (region_start != area_end) {
// A small piece of area left uniterated because area_end does not coincide
// with region end. Check whether region covering last part of area is
// dirty.
if (marks & mask) {
if (visit_dirty_region(region_start, area_end, copy_object_func)) {
newmarks |= mask;
}
}
}
return newmarks;
}
void Heap::IterateDirtyRegions(
PagedSpace* space,
DirtyRegionCallback visit_dirty_region,
ObjectSlotCallback copy_object_func,
ExpectedPageWatermarkState expected_page_watermark_state) {
PageIterator it(space, PageIterator::PAGES_IN_USE);
while (it.has_next()) {
Page* page = it.next();
uint32_t marks = page->GetRegionMarks();
if (marks != Page::kAllRegionsCleanMarks) {
Address start = page->ObjectAreaStart();
// Do not try to visit pointers beyond page allocation watermark.
// Page can contain garbage pointers there.
Address end;
if ((expected_page_watermark_state == WATERMARK_SHOULD_BE_VALID) ||
page->IsWatermarkValid()) {
end = page->AllocationWatermark();
} else {
end = page->CachedAllocationWatermark();
}
ASSERT(space == old_pointer_space_ ||
(space == map_space_ &&
((page->ObjectAreaStart() - end) % Map::kSize == 0)));
page->SetRegionMarks(IterateDirtyRegions(marks,
start,
end,
visit_dirty_region,
copy_object_func));
}
// Mark page watermark as invalid to maintain watermark validity invariant.
// See Page::FlipMeaningOfInvalidatedWatermarkFlag() for details.
page->InvalidateWatermark(true);
}
}
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_[kSymbolTableRootIndex]));
v->Synchronize("symbol_table");
if (mode != VISIT_ALL_IN_SCAVENGE) {
// Scavenge collections have special processing for this.
ExternalStringTable::Iterate(v);
}
v->Synchronize("external_string_table");
}
void Heap::IterateStrongRoots(ObjectVisitor* v, VisitMode mode) {
v->VisitPointers(&roots_[0], &roots_[kStrongRootListLength]);
v->Synchronize("strong_root_list");
v->VisitPointer(BitCast<Object**>(&hidden_symbol_));
v->Synchronize("symbol");
Bootstrapper::Iterate(v);
v->Synchronize("bootstrapper");
Top::Iterate(v);
v->Synchronize("top");
Relocatable::Iterate(v);
v->Synchronize("relocatable");
#ifdef ENABLE_DEBUGGER_SUPPORT
Debug::Iterate(v);
#endif
v->Synchronize("debug");
CompilationCache::Iterate(v);
v->Synchronize("compilationcache");
// Iterate over local handles in handle scopes.
HandleScopeImplementer::Iterate(v);
v->Synchronize("handlescope");
// 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) {
Builtins::IterateBuiltins(v);
}
v->Synchronize("builtins");
// Iterate over global handles.
if (mode == VISIT_ONLY_STRONG) {
GlobalHandles::IterateStrongRoots(v);
} else {
GlobalHandles::IterateAllRoots(v);
}
v->Synchronize("globalhandles");
// Iterate over pointers being held by inactive threads.
ThreadManager::Iterate(v);
v->Synchronize("threadmanager");
// Iterate over the pointers the Serialization/Deserialization code is
// holding.
// During garbage collection this keeps the partial snapshot cache alive.
// During deserialization of the startup snapshot this creates the partial
// snapshot cache and deserializes the objects it refers to. During
// serialization this does nothing, since the partial snapshot cache is
// empty. However the next thing we do is create the partial snapshot,
// filling up the partial snapshot cache with objects it needs as we go.
SerializerDeserializer::Iterate(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.
}
// Flag is set when the heap has been configured. The heap can be repeatedly
// configured through the API until it is setup.
static bool heap_configured = false;
// 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(int max_semispace_size, int max_old_gen_size) {
if (HasBeenSetup()) return false;
if (max_semispace_size > 0) max_semispace_size_ = max_semispace_size;
if (Snapshot::IsEnabled()) {
// If we are using a snapshot we always reserve the default amount
// of memory for each semispace because code in the snapshot has
// write-barrier code that relies on the size and alignment of new
// space. We therefore cannot use a larger max semispace size
// than the default reserved semispace size.
if (max_semispace_size_ > reserved_semispace_size_) {
max_semispace_size_ = reserved_semispace_size_;
}
} else {
// If we are not using snapshots we reserve space for the actual
// max semispace size.
reserved_semispace_size_ = max_semispace_size_;
}
if (max_old_gen_size > 0) max_old_generation_size_ = max_old_gen_size;
// The new space size must be a power of two to support single-bit testing
// for containment.
max_semispace_size_ = RoundUpToPowerOf2(max_semispace_size_);
reserved_semispace_size_ = RoundUpToPowerOf2(reserved_semispace_size_);
initial_semispace_size_ = Min(initial_semispace_size_, max_semispace_size_);
external_allocation_limit_ = 10 * max_semispace_size_;
// The old generation is paged.
max_old_generation_size_ = RoundUp(max_old_generation_size_, Page::kPageSize);
heap_configured = true;
return true;
}
bool Heap::ConfigureHeapDefault() {
return ConfigureHeap(FLAG_max_new_space_size / 2, FLAG_max_old_space_size);
}
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_pointer_space_size = old_pointer_space_->Size();
*stats->old_pointer_space_capacity = old_pointer_space_->Capacity();
*stats->old_data_space_size = old_data_space_->Size();
*stats->old_data_space_capacity = old_data_space_->Capacity();
*stats->code_space_size = code_space_->Size();
*stats->code_space_capacity = code_space_->Capacity();
*stats->map_space_size = map_space_->Size();
*stats->map_space_capacity = map_space_->Capacity();
*stats->cell_space_size = cell_space_->Size();
*stats->cell_space_capacity = cell_space_->Capacity();
*stats->lo_space_size = lo_space_->Size();
GlobalHandles::RecordStats(stats);
*stats->memory_allocator_size = MemoryAllocator::Size();
*stats->memory_allocator_capacity =
MemoryAllocator::Size() + MemoryAllocator::Available();
*stats->os_error = OS::GetLastError();
if (take_snapshot) {
HeapIterator iterator;
for (HeapObject* obj = iterator.next();
obj != NULL;
obj = iterator.next()) {
// Note: snapshot won't be precise because IsFreeListNode returns true
// for any bytearray.
if (FreeListNode::IsFreeListNode(obj)) continue;
InstanceType type = obj->map()->instance_type();
ASSERT(0 <= type && type <= LAST_TYPE);
stats->objects_per_type[type]++;
stats->size_per_type[type] += obj->Size();
}
}
}
int Heap::PromotedSpaceSize() {
return old_pointer_space_->Size()
+ old_data_space_->Size()
+ code_space_->Size()
+ map_space_->Size()
+ cell_space_->Size()
+ lo_space_->Size();
}
int Heap::PromotedExternalMemorySize() {
if (amount_of_external_allocated_memory_
<= amount_of_external_allocated_memory_at_last_global_gc_) return 0;
return amount_of_external_allocated_memory_
- amount_of_external_allocated_memory_at_last_global_gc_;
}
bool Heap::Setup(bool create_heap_objects) {
// 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 (eg, 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 (!heap_configured) {
if (!ConfigureHeapDefault()) return false;
}
ScavengingVisitor::Initialize();
NewSpaceScavenger::Initialize();
MarkCompactCollector::Initialize();
MarkMapPointersAsEncoded(false);
// Setup memory allocator and reserve a chunk of memory for new
// space. The chunk is double the size of the requested reserved
// new space size to ensure that we can find a pair of semispaces that
// are contiguous and aligned to their size.
if (!MemoryAllocator::Setup(MaxReserved())) return false;
void* chunk =
MemoryAllocator::ReserveInitialChunk(4 * reserved_semispace_size_);
if (chunk == NULL) return false;
// Align the pair of semispaces to their size, which must be a power
// of 2.
Address new_space_start =
RoundUp(reinterpret_cast<byte*>(chunk), 2 * reserved_semispace_size_);
if (!new_space_.Setup(new_space_start, 2 * reserved_semispace_size_)) {
return false;
}
// Initialize old pointer space.
old_pointer_space_ =
new OldSpace(max_old_generation_size_, OLD_POINTER_SPACE, NOT_EXECUTABLE);
if (old_pointer_space_ == NULL) return false;
if (!old_pointer_space_->Setup(NULL, 0)) return false;
// Initialize old data space.
old_data_space_ =
new OldSpace(max_old_generation_size_, OLD_DATA_SPACE, NOT_EXECUTABLE);
if (old_data_space_ == NULL) return false;
if (!old_data_space_->Setup(NULL, 0)) return false;
// Initialize the code space, set its maximum capacity to the old
// generation size. It needs executable memory.
// On 64-bit platform(s), we put all code objects in a 2 GB range of
// virtual address space, so that they can call each other with near calls.
if (code_range_size_ > 0) {
if (!CodeRange::Setup(code_range_size_)) {
return false;
}
}
code_space_ =
new OldSpace(max_old_generation_size_, CODE_SPACE, EXECUTABLE);
if (code_space_ == NULL) return false;
if (!code_space_->Setup(NULL, 0)) return false;
// Initialize map space.
map_space_ = new MapSpace(FLAG_use_big_map_space
? max_old_generation_size_
: MapSpace::kMaxMapPageIndex * Page::kPageSize,
FLAG_max_map_space_pages,
MAP_SPACE);
if (map_space_ == NULL) return false;
if (!map_space_->Setup(NULL, 0)) return false;
// Initialize global property cell space.
cell_space_ = new CellSpace(max_old_generation_size_, CELL_SPACE);
if (cell_space_ == NULL) return false;
if (!cell_space_->Setup(NULL, 0)) 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.
lo_space_ = new LargeObjectSpace(LO_SPACE);
if (lo_space_ == NULL) return false;
if (!lo_space_->Setup()) return false;
if (create_heap_objects) {
// Create initial maps.
if (!CreateInitialMaps()) return false;
if (!CreateApiObjects()) return false;
// Create initial objects
if (!CreateInitialObjects()) return false;
}
LOG(IntEvent("heap-capacity", Capacity()));
LOG(IntEvent("heap-available", Available()));
#ifdef ENABLE_LOGGING_AND_PROFILING
// This should be called only after initial objects have been created.
ProducerHeapProfile::Setup();
#endif
return true;
}
void Heap::SetStackLimits() {
// 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*>(
(StackGuard::jslimit() & ~kSmiTagMask) | kSmiTag);
roots_[kRealStackLimitRootIndex] =
reinterpret_cast<Object*>(
(StackGuard::real_jslimit() & ~kSmiTagMask) | kSmiTag);
}
void Heap::TearDown() {
if (FLAG_print_cumulative_gc_stat) {
PrintF("\n\n");
PrintF("gc_count=%d ", gc_count_);
PrintF("mark_sweep_count=%d ", ms_count_);
PrintF("mark_compact_count=%d ", mc_count_);
PrintF("max_gc_pause=%d ", GCTracer::get_max_gc_pause());
PrintF("min_in_mutator=%d ", GCTracer::get_min_in_mutator());
PrintF("max_alive_after_gc=%d ", GCTracer::get_max_alive_after_gc());
PrintF("\n\n");
}
GlobalHandles::TearDown();
ExternalStringTable::TearDown();
new_space_.TearDown();
if (old_pointer_space_ != NULL) {
old_pointer_space_->TearDown();
delete old_pointer_space_;
old_pointer_space_ = NULL;
}
if (old_data_space_ != NULL) {
old_data_space_->TearDown();
delete old_data_space_;
old_data_space_ = NULL;
}
if (code_space_ != NULL) {
code_space_->TearDown();
delete code_space_;
code_space_ = NULL;
}
if (map_space_ != NULL) {
map_space_->TearDown();
delete map_space_;
map_space_ = NULL;
}
if (cell_space_ != NULL) {
cell_space_->TearDown();
delete cell_space_;
cell_space_ = NULL;
}
if (lo_space_ != NULL) {
lo_space_->TearDown();
delete lo_space_;
lo_space_ = NULL;
}
MemoryAllocator::TearDown();
}
void Heap::Shrink() {
// Try to shrink all paged spaces.
PagedSpaces spaces;
for (PagedSpace* space = spaces.next(); space != NULL; space = spaces.next())
space->Shrink();
}
#ifdef ENABLE_HEAP_PROTECTION
void Heap::Protect() {
if (HasBeenSetup()) {
AllSpaces spaces;
for (Space* space = spaces.next(); space != NULL; space = spaces.next())
space->Protect();
}
}
void Heap::Unprotect() {
if (HasBeenSetup()) {
AllSpaces spaces;
for (Space* space = spaces.next(); space != NULL; space = spaces.next())
space->Unprotect();
}
}
#endif
void Heap::AddGCPrologueCallback(GCPrologueCallback callback, GCType gc_type) {
ASSERT(callback != NULL);
GCPrologueCallbackPair pair(callback, gc_type);
ASSERT(!gc_prologue_callbacks_.Contains(pair));
return gc_prologue_callbacks_.Add(pair);
}
void Heap::RemoveGCPrologueCallback(GCPrologueCallback callback) {
ASSERT(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(GCEpilogueCallback callback, GCType gc_type) {
ASSERT(callback != NULL);
GCEpilogueCallbackPair pair(callback, gc_type);
ASSERT(!gc_epilogue_callbacks_.Contains(pair));
return gc_epilogue_callbacks_.Add(pair);
}
void Heap::RemoveGCEpilogueCallback(GCEpilogueCallback callback) {
ASSERT(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();
}
#ifdef DEBUG
class PrintHandleVisitor: public ObjectVisitor {
public:
void VisitPointers(Object** start, Object** end) {
for (Object** p = start; p < end; p++)
PrintF(" handle %p to %p\n", p, *p);
}
};
void Heap::PrintHandles() {
PrintF("Handles:\n");
PrintHandleVisitor v;
HandleScopeImplementer::Iterate(&v);
}
#endif
Space* AllSpaces::next() {
switch (counter_++) {
case NEW_SPACE:
return Heap::new_space();
case OLD_POINTER_SPACE:
return Heap::old_pointer_space();
case OLD_DATA_SPACE:
return Heap::old_data_space();
case CODE_SPACE:
return Heap::code_space();
case MAP_SPACE:
return Heap::map_space();
case CELL_SPACE:
return Heap::cell_space();
case LO_SPACE:
return Heap::lo_space();
default:
return NULL;
}
}
PagedSpace* PagedSpaces::next() {
switch (counter_++) {
case OLD_POINTER_SPACE:
return Heap::old_pointer_space();
case OLD_DATA_SPACE:
return Heap::old_data_space();
case CODE_SPACE:
return Heap::code_space();
case MAP_SPACE:
return Heap::map_space();
case CELL_SPACE:
return Heap::cell_space();
default:
return NULL;
}
}
OldSpace* OldSpaces::next() {
switch (counter_++) {
case OLD_POINTER_SPACE:
return Heap::old_pointer_space();
case OLD_DATA_SPACE:
return Heap::old_data_space();
case CODE_SPACE:
return Heap::code_space();
default:
return NULL;
}
}
SpaceIterator::SpaceIterator() : current_space_(FIRST_SPACE), iterator_(NULL) {
}
SpaceIterator::~SpaceIterator() {
// Delete active iterator if any.
delete iterator_;
}
bool SpaceIterator::has_next() {
// Iterate until no more spaces.
return current_space_ != LAST_SPACE;
}
ObjectIterator* SpaceIterator::next() {
if (iterator_ != NULL) {
delete iterator_;
iterator_ = NULL;
// Move to the next space
current_space_++;
if (current_space_ > LAST_SPACE) {
return NULL;
}
}
// Return iterator for the new current space.
return CreateIterator();
}
// Create an iterator for the space to iterate.
ObjectIterator* SpaceIterator::CreateIterator() {
ASSERT(iterator_ == NULL);
switch (current_space_) {
case NEW_SPACE:
iterator_ = new SemiSpaceIterator(Heap::new_space());
break;
case OLD_POINTER_SPACE:
iterator_ = new HeapObjectIterator(Heap::old_pointer_space());
break;
case OLD_DATA_SPACE:
iterator_ = new HeapObjectIterator(Heap::old_data_space());
break;
case CODE_SPACE:
iterator_ = new HeapObjectIterator(Heap::code_space());
break;
case MAP_SPACE:
iterator_ = new HeapObjectIterator(Heap::map_space());
break;
case CELL_SPACE:
iterator_ = new HeapObjectIterator(Heap::cell_space());
break;
case LO_SPACE:
iterator_ = new LargeObjectIterator(Heap::lo_space());
break;
}
// Return the newly allocated iterator;
ASSERT(iterator_ != NULL);
return iterator_;
}
HeapIterator::HeapIterator() {
Init();
}
HeapIterator::~HeapIterator() {
Shutdown();
}
void HeapIterator::Init() {
// Start the iteration.
space_iterator_ = new SpaceIterator();
object_iterator_ = space_iterator_->next();
}
void HeapIterator::Shutdown() {
// Make sure the last iterator is deallocated.
delete space_iterator_;
space_iterator_ = NULL;
object_iterator_ = NULL;
}
HeapObject* HeapIterator::next() {
// No iterator means we are done.
if (object_iterator_ == NULL) return NULL;
if (HeapObject* obj = object_iterator_->next_object()) {
// 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();
if (HeapObject* obj = object_iterator_->next_object()) {
return obj;
}
}
}
// Done with the last space.
object_iterator_ = NULL;
return NULL;
}
void HeapIterator::reset() {
// Restart the iterator.
Shutdown();
Init();
}
#ifdef DEBUG
static bool search_for_any_global;
static Object* search_target;
static bool found_target;
static List<Object*> object_stack(20);
// Tags 0, 1, and 3 are used. Use 2 for marking visited HeapObject.
static const int kMarkTag = 2;
static void MarkObjectRecursively(Object** p);
class MarkObjectVisitor : public ObjectVisitor {
public:
void VisitPointers(Object** start, Object** end) {
// Copy all HeapObject pointers in [start, end)
for (Object** p = start; p < end; p++) {
if ((*p)->IsHeapObject())
MarkObjectRecursively(p);
}
}
};
static MarkObjectVisitor mark_visitor;
static void MarkObjectRecursively(Object** p) {
if (!(*p)->IsHeapObject()) return;
HeapObject* obj = HeapObject::cast(*p);
Object* map = obj->map();
if (!map->IsHeapObject()) return; // visited before
if (found_target) return; // stop if target found
object_stack.Add(obj);
if ((search_for_any_global && obj->IsJSGlobalObject()) ||
(!search_for_any_global && (obj == search_target))) {
found_target = true;
return;
}
// not visited yet
Map* map_p = reinterpret_cast<Map*>(HeapObject::cast(map));
Address map_addr = map_p->address();
obj->set_map(reinterpret_cast<Map*>(map_addr + kMarkTag));
MarkObjectRecursively(&map);
obj->IterateBody(map_p->instance_type(), obj->SizeFromMap(map_p),
&mark_visitor);
if (!found_target) // don't pop if found the target
object_stack.RemoveLast();
}
static void UnmarkObjectRecursively(Object** p);
class UnmarkObjectVisitor : public ObjectVisitor {
public:
void VisitPointers(Object** start, Object** end) {
// Copy all HeapObject pointers in [start, end)
for (Object** p = start; p < end; p++) {
if ((*p)->IsHeapObject())
UnmarkObjectRecursively(p);
}
}
};
static UnmarkObjectVisitor unmark_visitor;
static void UnmarkObjectRecursively(Object** p) {
if (!(*p)->IsHeapObject()) return;
HeapObject* obj = HeapObject::cast(*p);
Object* map = obj->map();
if (map->IsHeapObject()) return; // unmarked already
Address map_addr = reinterpret_cast<Address>(map);
map_addr -= kMarkTag;
ASSERT_TAG_ALIGNED(map_addr);
HeapObject* map_p = HeapObject::FromAddress(map_addr);
obj->set_map(reinterpret_cast<Map*>(map_p));
UnmarkObjectRecursively(reinterpret_cast<Object**>(&map_p));
obj->IterateBody(Map::cast(map_p)->instance_type(),
obj->SizeFromMap(Map::cast(map_p)),
&unmark_visitor);
}
static void MarkRootObjectRecursively(Object** root) {
if (search_for_any_global) {
ASSERT(search_target == NULL);
} else {
ASSERT(search_target->IsHeapObject());
}
found_target = false;
object_stack.Clear();
MarkObjectRecursively(root);
UnmarkObjectRecursively(root);
if (found_target) {
PrintF("=====================================\n");
PrintF("==== Path to object ====\n");
PrintF("=====================================\n\n");
ASSERT(!object_stack.is_empty());
for (int i = 0; i < object_stack.length(); i++) {
if (i > 0) PrintF("\n |\n |\n V\n\n");
Object* obj = object_stack[i];
obj->Print();
}
PrintF("=====================================\n");
}
}
// Helper class for visiting HeapObjects recursively.
class MarkRootVisitor: public ObjectVisitor {
public:
void VisitPointers(Object** start, Object** end) {
// Visit all HeapObject pointers in [start, end)
for (Object** p = start; p < end; p++) {
if ((*p)->IsHeapObject())
MarkRootObjectRecursively(p);
}
}
};
// 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) {
search_target = target;
search_for_any_global = false;
MarkRootVisitor root_visitor;
IterateRoots(&root_visitor, 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() {
search_target = NULL;
search_for_any_global = true;
MarkRootVisitor root_visitor;
IterateRoots(&root_visitor, VISIT_ONLY_STRONG);
}
#endif
static int CountTotalHolesSize() {
int holes_size = 0;
OldSpaces spaces;
for (OldSpace* space = spaces.next();
space != NULL;
space = spaces.next()) {
holes_size += space->Waste() + space->AvailableFree();
}
return holes_size;
}
GCTracer::GCTracer()
: start_time_(0.0),
start_size_(0),
gc_count_(0),
full_gc_count_(0),
is_compacting_(false),
marked_count_(0),
allocated_since_last_gc_(0),
spent_in_mutator_(0),
promoted_objects_size_(0) {
// These two fields reflect the state of the previous full collection.
// Set them before they are changed by the collector.
previous_has_compacted_ = MarkCompactCollector::HasCompacted();
previous_marked_count_ = MarkCompactCollector::previous_marked_count();
if (!FLAG_trace_gc && !FLAG_print_cumulative_gc_stat) return;
start_time_ = OS::TimeCurrentMillis();
start_size_ = Heap::SizeOfObjects();
for (int i = 0; i < Scope::kNumberOfScopes; i++) {
scopes_[i] = 0;
}
in_free_list_or_wasted_before_gc_ = CountTotalHolesSize();
allocated_since_last_gc_ = Heap::SizeOfObjects() - alive_after_last_gc_;
if (last_gc_end_timestamp_ > 0) {
spent_in_mutator_ = Max(start_time_ - last_gc_end_timestamp_, 0.0);
}
}
GCTracer::~GCTracer() {
// Printf ONE line iff flag is set.
if (!FLAG_trace_gc && !FLAG_print_cumulative_gc_stat) return;
bool first_gc = (last_gc_end_timestamp_ == 0);
alive_after_last_gc_ = Heap::SizeOfObjects();
last_gc_end_timestamp_ = OS::TimeCurrentMillis();
int time = static_cast<int>(last_gc_end_timestamp_ - start_time_);
// Update cumulative GC statistics if required.
if (FLAG_print_cumulative_gc_stat) {
max_gc_pause_ = Max(max_gc_pause_, time);
max_alive_after_gc_ = Max(max_alive_after_gc_, alive_after_last_gc_);
if (!first_gc) {
min_in_mutator_ = Min(min_in_mutator_,
static_cast<int>(spent_in_mutator_));
}
}
if (!FLAG_trace_gc_nvp) {
int external_time = static_cast<int>(scopes_[Scope::EXTERNAL]);
PrintF("%s %.1f -> %.1f MB, ",
CollectorString(),
static_cast<double>(start_size_) / MB,
SizeOfHeapObjects());
if (external_time > 0) PrintF("%d / ", external_time);
PrintF("%d ms.\n", time);
} else {
PrintF("pause=%d ", time);
PrintF("mutator=%d ",
static_cast<int>(spent_in_mutator_));
PrintF("gc=");
switch (collector_) {
case SCAVENGER:
PrintF("s");
break;
case MARK_COMPACTOR:
PrintF(MarkCompactCollector::HasCompacted() ? "mc" : "ms");
break;
default:
UNREACHABLE();
}
PrintF(" ");
PrintF("external=%d ", static_cast<int>(scopes_[Scope::EXTERNAL]));
PrintF("mark=%d ", static_cast<int>(scopes_[Scope::MC_MARK]));
PrintF("sweep=%d ", static_cast<int>(scopes_[Scope::MC_SWEEP]));
PrintF("sweepns=%d ", static_cast<int>(scopes_[Scope::MC_SWEEP_NEWSPACE]));
PrintF("compact=%d ", static_cast<int>(scopes_[Scope::MC_COMPACT]));
PrintF("total_size_before=%d ", start_size_);
PrintF("total_size_after=%d ", Heap::SizeOfObjects());
PrintF("holes_size_before=%d ", in_free_list_or_wasted_before_gc_);
PrintF("holes_size_after=%d ", CountTotalHolesSize());
PrintF("allocated=%d ", allocated_since_last_gc_);
PrintF("promoted=%d ", promoted_objects_size_);
PrintF("\n");
}
#if defined(ENABLE_LOGGING_AND_PROFILING)
Heap::PrintShortHeapStatistics();
#endif
}
const char* GCTracer::CollectorString() {
switch (collector_) {
case SCAVENGER:
return "Scavenge";
case MARK_COMPACTOR:
return MarkCompactCollector::HasCompacted() ? "Mark-compact"
: "Mark-sweep";
}
return "Unknown GC";
}
int KeyedLookupCache::Hash(Map* map, String* name) {
// Uses only lower 32 bits if pointers are larger.
uintptr_t addr_hash =
static_cast<uint32_t>(reinterpret_cast<uintptr_t>(map)) >> kMapHashShift;
return static_cast<uint32_t>((addr_hash ^ name->Hash()) & kCapacityMask);
}
int KeyedLookupCache::Lookup(Map* map, String* name) {
int index = Hash(map, name);
Key& key = keys_[index];
if ((key.map == map) && key.name->Equals(name)) {
return field_offsets_[index];
}
return -1;
}
void KeyedLookupCache::Update(Map* map, String* name, int field_offset) {
String* symbol;
if (Heap::LookupSymbolIfExists(name, &symbol)) {
int index = Hash(map, symbol);
Key& key = keys_[index];
key.map = map;
key.name = symbol;
field_offsets_[index] = field_offset;
}
}
void KeyedLookupCache::Clear() {
for (int index = 0; index < kLength; index++) keys_[index].map = NULL;
}
KeyedLookupCache::Key KeyedLookupCache::keys_[KeyedLookupCache::kLength];
int KeyedLookupCache::field_offsets_[KeyedLookupCache::kLength];
void DescriptorLookupCache::Clear() {
for (int index = 0; index < kLength; index++) keys_[index].array = NULL;
}
DescriptorLookupCache::Key
DescriptorLookupCache::keys_[DescriptorLookupCache::kLength];
int DescriptorLookupCache::results_[DescriptorLookupCache::kLength];
#ifdef DEBUG
bool Heap::GarbageCollectionGreedyCheck() {
ASSERT(FLAG_gc_greedy);
if (Bootstrapper::IsActive()) return true;
if (disallow_allocation_failure()) return true;
return CollectGarbage(0, NEW_SPACE);
}
#endif
TranscendentalCache::TranscendentalCache(TranscendentalCache::Type t)
: type_(t) {
uint32_t in0 = 0xffffffffu; // Bit-pattern for a NaN that isn't
uint32_t in1 = 0xffffffffu; // generated by the FPU.
for (int i = 0; i < kCacheSize; i++) {
elements_[i].in[0] = in0;
elements_[i].in[1] = in1;
elements_[i].output = NULL;
}
}
TranscendentalCache* TranscendentalCache::caches_[kNumberOfCaches];
void TranscendentalCache::Clear() {
for (int i = 0; i < kNumberOfCaches; i++) {
if (caches_[i] != NULL) {
delete caches_[i];
caches_[i] = NULL;
}
}
}
void ExternalStringTable::CleanUp() {
int last = 0;
for (int i = 0; i < new_space_strings_.length(); ++i) {
if (new_space_strings_[i] == Heap::raw_unchecked_null_value()) continue;
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);
last = 0;
for (int i = 0; i < old_space_strings_.length(); ++i) {
if (old_space_strings_[i] == Heap::raw_unchecked_null_value()) continue;
ASSERT(!Heap::InNewSpace(old_space_strings_[i]));
old_space_strings_[last++] = old_space_strings_[i];
}
old_space_strings_.Rewind(last);
Verify();
}
void ExternalStringTable::TearDown() {
new_space_strings_.Free();
old_space_strings_.Free();
}
List<Object*> ExternalStringTable::new_space_strings_;
List<Object*> ExternalStringTable::old_space_strings_;
} } // namespace v8::internal