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bf948c8313
v8/src/heap.cc
bak@chromium.org bf948c8313 - Optimized CopyFixedArray and CopyJSObject. 
- Refactored block copying.

Review URL: http://codereview.chromium.org/7863

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@548 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2008-10-22 08:21:18 +00:00

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// Copyright 2006-2008 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 "global-handles.h"
#include "jsregexp.h"
#include "mark-compact.h"
#include "natives.h"
#include "scanner.h"
#include "scopeinfo.h"
#include "v8threads.h"
namespace v8 { namespace internal {
#define ROOT_ALLOCATION(type, name) type* Heap::name##_;
ROOT_LIST(ROOT_ALLOCATION)
#undef ROOT_ALLOCATION
#define STRUCT_ALLOCATION(NAME, Name, name) Map* Heap::name##_map_;
STRUCT_LIST(STRUCT_ALLOCATION)
#undef STRUCT_ALLOCATION
#define SYMBOL_ALLOCATION(name, string) String* Heap::name##_;
SYMBOL_LIST(SYMBOL_ALLOCATION)
#undef SYMBOL_ALLOCATION
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;
LargeObjectSpace* Heap::lo_space_ = NULL;
int Heap::promoted_space_limit_ = 0;
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.
int Heap::semispace_size_ = 2*MB;
int Heap::old_generation_size_ = 512*MB;
int Heap::initial_semispace_size_ = 256*KB;
GCCallback Heap::global_gc_prologue_callback_ = NULL;
GCCallback Heap::global_gc_epilogue_callback_ = NULL;
// Variables set based on semispace_size_ and old_generation_size_ in
// ConfigureHeap.
int Heap::young_generation_size_ = 0; // Will be 2 * semispace_size_.
// Double the new space after this many scavenge collections.
int Heap::new_space_growth_limit_ = 8;
int Heap::scavenge_count_ = 0;
Heap::HeapState Heap::gc_state_ = NOT_IN_GC;
int Heap::mc_count_ = 0;
int Heap::gc_count_ = 0;
#ifdef DEBUG
bool Heap::allocation_allowed_ = true;
int Heap::allocation_timeout_ = 0;
bool Heap::disallow_allocation_failure_ = false;
#endif // DEBUG
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();
}
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();
}
bool Heap::HasBeenSetup() {
return old_pointer_space_ != NULL &&
old_data_space_ != NULL &&
code_space_ != NULL &&
map_space_ != NULL &&
lo_space_ != NULL;
}
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 (PromotedSpaceSize() + PromotedExternalMemorySize()
> promoted_space_limit_) {
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
}
// 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) {
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() {
RegExpImpl::NewSpaceCollectionPrologue();
gc_count_++;
#ifdef DEBUG
ASSERT(allocation_allowed_ && gc_state_ == NOT_IN_GC);
allow_allocation(false);
if (FLAG_verify_heap) {
Verify();
}
if (FLAG_gc_verbose) Print();
if (FLAG_print_rset) {
// Not all spaces have remembered set bits that we care about.
old_pointer_space_->PrintRSet();
map_space_->PrintRSet();
lo_space_->PrintRSet();
}
#endif
#if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
ReportStatisticsBeforeGC();
#endif
}
int Heap::SizeOfObjects() {
int total = 0;
AllSpaces spaces;
while (Space* 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());
SymbolTable* symbol_table = SymbolTable::cast(Heap::symbol_table_);
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
}
void Heap::CollectAllGarbage() {
// 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.
CollectGarbage(0, OLD_POINTER_SPACE);
}
bool Heap::CollectGarbage(int requested_size, AllocationSpace space) {
// 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);
StatsRate* rate = (collector == SCAVENGER)
? &Counters::gc_scavenger
: &Counters::gc_compactor;
rate->Start();
PerformGarbageCollection(space, collector, &tracer);
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 LO_SPACE:
return lo_space_->Available() >= requested_size;
}
return false;
}
void Heap::PerformScavenge() {
GCTracer tracer;
PerformGarbageCollection(NEW_SPACE, SCAVENGER, &tracer);
}
void Heap::PerformGarbageCollection(AllocationSpace space,
GarbageCollector collector,
GCTracer* tracer) {
if (collector == MARK_COMPACTOR && global_gc_prologue_callback_) {
ASSERT(!allocation_allowed_);
global_gc_prologue_callback_();
}
if (collector == MARK_COMPACTOR) {
MarkCompact(tracer);
int promoted_space_size = PromotedSpaceSize();
promoted_space_limit_ =
promoted_space_size + Max(2 * MB, (promoted_space_size/100) * 35);
old_gen_exhausted_ = false;
// If we have used the mark-compact collector to collect the new
// space, and it has not compacted the new space, we force a
// separate scavenge collection. This is a hack. It covers the
// case where (1) a new space collection was requested, (2) the
// collector selection policy selected the mark-compact collector,
// and (3) the mark-compact collector policy selected not to
// compact the new space. In that case, there is no more (usable)
// free space in the new space after the collection compared to
// before.
if (space == NEW_SPACE && !MarkCompactCollector::HasCompacted()) {
Scavenge();
}
} else {
Scavenge();
}
Counters::objs_since_last_young.Set(0);
// Process weak handles post gc.
GlobalHandles::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_;
}
if (collector == MARK_COMPACTOR && global_gc_epilogue_callback_) {
ASSERT(!allocation_allowed_);
global_gc_epilogue_callback_();
}
}
void Heap::MarkCompact(GCTracer* tracer) {
gc_state_ = MARK_COMPACT;
mc_count_++;
tracer->set_full_gc_count(mc_count_);
LOG(ResourceEvent("markcompact", "begin"));
MarkCompactPrologue();
MarkCompactCollector::CollectGarbage(tracer);
MarkCompactEpilogue();
LOG(ResourceEvent("markcompact", "end"));
gc_state_ = NOT_IN_GC;
Shrink();
Counters::objs_since_last_full.Set(0);
}
void Heap::MarkCompactPrologue() {
CompilationCache::MarkCompactPrologue();
RegExpImpl::OldSpaceCollectionPrologue();
Top::MarkCompactPrologue();
ThreadManager::MarkCompactPrologue();
}
void Heap::MarkCompactEpilogue() {
Top::MarkCompactEpilogue();
ThreadManager::MarkCompactEpilogue();
}
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));
}
};
// Shared state read by the scavenge collector and set by ScavengeObject.
static Address promoted_top = NULL;
#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)));
}
}
}
};
#endif
void Heap::Scavenge() {
#ifdef DEBUG
if (FLAG_enable_slow_asserts) {
VerifyNonPointerSpacePointersVisitor v;
HeapObjectIterator it(code_space_);
while (it.has_next()) {
HeapObject* object = it.next();
if (object->IsCode()) {
Code::cast(object)->ConvertICTargetsFromAddressToObject();
}
object->Iterate(&v);
if (object->IsCode()) {
Code::cast(object)->ConvertICTargetsFromObjectToAddress();
}
}
}
#endif
gc_state_ = SCAVENGE;
// Implements Cheney's copying algorithm
LOG(ResourceEvent("scavenge", "begin"));
scavenge_count_++;
if (new_space_.Capacity() < new_space_.MaximumCapacity() &&
scavenge_count_ > new_space_growth_limit_) {
// Double the size of the new space, and double the limit. The next
// doubling attempt will occur after the current new_space_growth_limit_
// more collections.
// TODO(1240712): NewSpace::Double has a return value which is
// ignored here.
new_space_.Double();
new_space_growth_limit_ *= 2;
}
// 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 in either the to space
// or the old space. For to space objects, we use a mark. Newly copied
// objects lie between the mark and the allocation top. For objects
// promoted to old space, we write their addresses downward from the top of
// the new space. Sweeping newly promoted objects requires an allocation
// pointer and a mark. Note that the allocation pointer 'top' actually
// moves downward from the high address in the to space.
//
// 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. Using the new space to record promoted addresses makes the
// scavenge collector agnostic to the allocation strategy (eg, linear or
// free-list) used in old space.
Address new_mark = new_space_.ToSpaceLow();
Address promoted_mark = new_space_.ToSpaceHigh();
promoted_top = new_space_.ToSpaceHigh();
ScavengeVisitor scavenge_visitor;
// Copy roots.
IterateRoots(&scavenge_visitor);
// Copy objects reachable from the old generation. By definition, there
// are no intergenerational pointers in code or data spaces.
IterateRSet(old_pointer_space_, &ScavengePointer);
IterateRSet(map_space_, &ScavengePointer);
lo_space_->IterateRSet(&ScavengePointer);
bool has_processed_weak_pointers = false;
while (true) {
ASSERT(new_mark <= new_space_.top());
ASSERT(promoted_mark >= promoted_top);
// Copy objects reachable from newly copied objects.
while (new_mark < new_space_.top() || promoted_mark > promoted_top) {
// Sweep newly copied objects in the to space. The allocation pointer
// can change during sweeping.
Address previous_top = new_space_.top();
SemiSpaceIterator new_it(new_space(), new_mark);
while (new_it.has_next()) {
new_it.next()->Iterate(&scavenge_visitor);
}
new_mark = previous_top;
// Sweep newly copied objects in the old space. The promotion 'top'
// pointer could change during sweeping.
previous_top = promoted_top;
for (Address current = promoted_mark - kPointerSize;
current >= previous_top;
current -= kPointerSize) {
HeapObject* object = HeapObject::cast(Memory::Object_at(current));
object->Iterate(&scavenge_visitor);
UpdateRSet(object);
}
promoted_mark = previous_top;
}
if (has_processed_weak_pointers) break; // We are done.
// Copy objects reachable from weak pointers.
GlobalHandles::IterateWeakRoots(&scavenge_visitor);
has_processed_weak_pointers = true;
}
// Set age mark.
new_space_.set_age_mark(new_mark);
LOG(ResourceEvent("scavenge", "end"));
gc_state_ = NOT_IN_GC;
}
void Heap::ClearRSetRange(Address start, int size_in_bytes) {
uint32_t start_bit;
Address start_word_address =
Page::ComputeRSetBitPosition(start, 0, &start_bit);
uint32_t end_bit;
Address end_word_address =
Page::ComputeRSetBitPosition(start + size_in_bytes - kIntSize,
0,
&end_bit);
// We want to clear the bits in the starting word starting with the
// first bit, and in the ending word up to and including the last
// bit. Build a pair of bitmasks to do that.
uint32_t start_bitmask = start_bit - 1;
uint32_t end_bitmask = ~((end_bit << 1) - 1);
// If the start address and end address are the same, we mask that
// word once, otherwise mask the starting and ending word
// separately and all the ones in between.
if (start_word_address == end_word_address) {
Memory::uint32_at(start_word_address) &= (start_bitmask | end_bitmask);
} else {
Memory::uint32_at(start_word_address) &= start_bitmask;
Memory::uint32_at(end_word_address) &= end_bitmask;
start_word_address += kIntSize;
memset(start_word_address, 0, end_word_address - start_word_address);
}
}
class UpdateRSetVisitor: public ObjectVisitor {
public:
void VisitPointer(Object** p) {
UpdateRSet(p);
}
void VisitPointers(Object** start, Object** end) {
// Update a store into slots [start, end), used (a) to update remembered
// set when promoting a young object to old space or (b) to rebuild
// remembered sets after a mark-compact collection.
for (Object** p = start; p < end; p++) UpdateRSet(p);
}
private:
void UpdateRSet(Object** p) {
// The remembered set should not be set. It should be clear for objects
// newly copied to old space, and it is cleared before rebuilding in the
// mark-compact collector.
ASSERT(!Page::IsRSetSet(reinterpret_cast<Address>(p), 0));
if (Heap::InNewSpace(*p)) {
Page::SetRSet(reinterpret_cast<Address>(p), 0);
}
}
};
int Heap::UpdateRSet(HeapObject* obj) {
ASSERT(!InNewSpace(obj));
// Special handling of fixed arrays to iterate the body based on the start
// address and offset. Just iterating the pointers as in UpdateRSetVisitor
// will not work because Page::SetRSet needs to have the start of the
// object.
if (obj->IsFixedArray()) {
FixedArray* array = FixedArray::cast(obj);
int length = array->length();
for (int i = 0; i < length; i++) {
int offset = FixedArray::kHeaderSize + i * kPointerSize;
ASSERT(!Page::IsRSetSet(obj->address(), offset));
if (Heap::InNewSpace(array->get(i))) {
Page::SetRSet(obj->address(), offset);
}
}
} else if (!obj->IsCode()) {
// Skip code object, we know it does not contain inter-generational
// pointers.
UpdateRSetVisitor v;
obj->Iterate(&v);
}
return obj->Size();
}
void Heap::RebuildRSets() {
// By definition, we do not care about remembered set bits in code or data
// spaces.
map_space_->ClearRSet();
RebuildRSets(map_space_);
old_pointer_space_->ClearRSet();
RebuildRSets(old_pointer_space_);
Heap::lo_space_->ClearRSet();
RebuildRSets(lo_space_);
}
void Heap::RebuildRSets(PagedSpace* space) {
HeapObjectIterator it(space);
while (it.has_next()) Heap::UpdateRSet(it.next());
}
void Heap::RebuildRSets(LargeObjectSpace* space) {
LargeObjectIterator it(space);
while (it.has_next()) Heap::UpdateRSet(it.next());
}
#if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
void Heap::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 (new_space_.Contains(obj)) {
new_space_.RecordAllocation(obj);
} else {
new_space_.RecordPromotion(obj);
}
}
}
#endif // defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
HeapObject* Heap::MigrateObject(HeapObject* source,
HeapObject* target,
int size) {
// Copy the content of source to target.
CopyBlock(reinterpret_cast<Object**>(target->address()),
reinterpret_cast<Object**>(source->address()),
size);
// Set the forwarding address.
source->set_map_word(MapWord::FromForwardingAddress(target));
// Update NewSpace stats if necessary.
#if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
RecordCopiedObject(target);
#endif
return target;
}
// Inlined function.
void Heap::ScavengeObject(HeapObject** p, HeapObject* object) {
ASSERT(InFromSpace(object));
// We use the first word (where the map pointer usually is) of a heap
// object to record the forwarding pointer. A forwarding pointer can
// point to an old space, the code space, or the to space of the new
// generation.
MapWord first_word = object->map_word();
// If the first word is a forwarding address, the object has already been
// copied.
if (first_word.IsForwardingAddress()) {
*p = first_word.ToForwardingAddress();
return;
}
// Call the slow part of scavenge object.
return ScavengeObjectSlow(p, object);
}
static inline bool IsShortcutCandidate(HeapObject* object, Map* map) {
// A ConString object with Heap::empty_string() as the right side
// is a candidate for being shortcut by the scavenger.
ASSERT(object->map() == map);
return (map->instance_type() < FIRST_NONSTRING_TYPE) &&
(String::cast(object)->map_representation_tag(map) == kConsStringTag) &&
(ConsString::cast(object)->second() == Heap::empty_string());
}
void Heap::ScavengeObjectSlow(HeapObject** p, HeapObject* object) {
ASSERT(InFromSpace(object));
MapWord first_word = object->map_word();
ASSERT(!first_word.IsForwardingAddress());
// Optimization: Bypass flattened ConsString objects.
if (IsShortcutCandidate(object, first_word.ToMap())) {
object = HeapObject::cast(ConsString::cast(object)->first());
*p = object;
// After patching *p we have to repeat the checks that object is in the
// active semispace of the young generation and not already copied.
if (!InNewSpace(object)) return;
first_word = object->map_word();
if (first_word.IsForwardingAddress()) {
*p = first_word.ToForwardingAddress();
return;
}
}
int object_size = object->SizeFromMap(first_word.ToMap());
// If the object should be promoted, we try to copy it to old space.
if (ShouldBePromoted(object->address(), object_size)) {
OldSpace* target_space = Heap::TargetSpace(object);
ASSERT(target_space == Heap::old_pointer_space_ ||
target_space == Heap::old_data_space_);
Object* result = target_space->AllocateRaw(object_size);
if (!result->IsFailure()) {
*p = MigrateObject(object, HeapObject::cast(result), object_size);
if (target_space == Heap::old_pointer_space_) {
// Record the object's address at the top of the to space, to allow
// it to be swept by the scavenger.
promoted_top -= kPointerSize;
Memory::Object_at(promoted_top) = *p;
} else {
#ifdef DEBUG
// Objects promoted to the data space should not have pointers to
// new space.
VerifyNonPointerSpacePointersVisitor v;
(*p)->Iterate(&v);
#endif
}
return;
}
}
// The object should remain in new space or the old space allocation failed.
Object* result = new_space_.AllocateRaw(object_size);
// Failed allocation at this point is utterly unexpected.
ASSERT(!result->IsFailure());
*p = MigrateObject(object, HeapObject::cast(result), object_size);
}
void Heap::ScavengePointer(HeapObject** p) {
ScavengeObject(p, *p);
}
Object* Heap::AllocatePartialMap(InstanceType instance_type,
int instance_size) {
Object* result = AllocateRawMap(Map::kSize);
if (result->IsFailure()) return result;
// Map::cast cannot be used due to uninitialized map field.
reinterpret_cast<Map*>(result)->set_map(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_inobject_properties(0);
reinterpret_cast<Map*>(result)->set_unused_property_fields(0);
return result;
}
Object* Heap::AllocateMap(InstanceType instance_type, int instance_size) {
Object* result = AllocateRawMap(Map::kSize);
if (result->IsFailure()) return result;
Map* map = reinterpret_cast<Map*>(result);
map->set_map(meta_map());
map->set_instance_type(instance_type);
map->set_prototype(null_value());
map->set_constructor(null_value());
map->set_instance_size(instance_size);
map->set_inobject_properties(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);
return map;
}
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.
meta_map_ = reinterpret_cast<Map*>(obj);
meta_map()->set_map(meta_map());
obj = AllocatePartialMap(FIXED_ARRAY_TYPE, Array::kHeaderSize);
if (obj->IsFailure()) return false;
fixed_array_map_ = Map::cast(obj);
obj = AllocatePartialMap(ODDBALL_TYPE, Oddball::kSize);
if (obj->IsFailure()) return false;
oddball_map_ = Map::cast(obj);
// Allocate the empty array
obj = AllocateEmptyFixedArray();
if (obj->IsFailure()) return false;
empty_fixed_array_ = FixedArray::cast(obj);
obj = Allocate(oddball_map(), OLD_DATA_SPACE);
if (obj->IsFailure()) return false;
null_value_ = obj;
// Allocate the empty descriptor array. AllocateMap can now be used.
obj = AllocateEmptyFixedArray();
if (obj->IsFailure()) return false;
// There is a check against empty_descriptor_array() in cast().
empty_descriptor_array_ = reinterpret_cast<DescriptorArray*>(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(HEAP_NUMBER_TYPE, HeapNumber::kSize);
if (obj->IsFailure()) return false;
heap_number_map_ = Map::cast(obj);
obj = AllocateMap(PROXY_TYPE, Proxy::kSize);
if (obj->IsFailure()) return false;
proxy_map_ = Map::cast(obj);
#define ALLOCATE_STRING_MAP(type, size, name) \
obj = AllocateMap(type, size); \
if (obj->IsFailure()) return false; \
name##_map_ = Map::cast(obj);
STRING_TYPE_LIST(ALLOCATE_STRING_MAP);
#undef ALLOCATE_STRING_MAP
obj = AllocateMap(SHORT_STRING_TYPE, SeqTwoByteString::kHeaderSize);
if (obj->IsFailure()) return false;
undetectable_short_string_map_ = Map::cast(obj);
undetectable_short_string_map_->set_is_undetectable();
obj = AllocateMap(MEDIUM_STRING_TYPE, SeqTwoByteString::kHeaderSize);
if (obj->IsFailure()) return false;
undetectable_medium_string_map_ = Map::cast(obj);
undetectable_medium_string_map_->set_is_undetectable();
obj = AllocateMap(LONG_STRING_TYPE, SeqTwoByteString::kHeaderSize);
if (obj->IsFailure()) return false;
undetectable_long_string_map_ = Map::cast(obj);
undetectable_long_string_map_->set_is_undetectable();
obj = AllocateMap(SHORT_ASCII_STRING_TYPE, SeqAsciiString::kHeaderSize);
if (obj->IsFailure()) return false;
undetectable_short_ascii_string_map_ = Map::cast(obj);
undetectable_short_ascii_string_map_->set_is_undetectable();
obj = AllocateMap(MEDIUM_ASCII_STRING_TYPE, SeqAsciiString::kHeaderSize);
if (obj->IsFailure()) return false;
undetectable_medium_ascii_string_map_ = Map::cast(obj);
undetectable_medium_ascii_string_map_->set_is_undetectable();
obj = AllocateMap(LONG_ASCII_STRING_TYPE, SeqAsciiString::kHeaderSize);
if (obj->IsFailure()) return false;
undetectable_long_ascii_string_map_ = Map::cast(obj);
undetectable_long_ascii_string_map_->set_is_undetectable();
obj = AllocateMap(BYTE_ARRAY_TYPE, Array::kHeaderSize);
if (obj->IsFailure()) return false;
byte_array_map_ = Map::cast(obj);
obj = AllocateMap(CODE_TYPE, Code::kHeaderSize);
if (obj->IsFailure()) return false;
code_map_ = Map::cast(obj);
obj = AllocateMap(FILLER_TYPE, kPointerSize);
if (obj->IsFailure()) return false;
one_word_filler_map_ = Map::cast(obj);
obj = AllocateMap(FILLER_TYPE, 2 * kPointerSize);
if (obj->IsFailure()) return false;
two_word_filler_map_ = Map::cast(obj);
#define ALLOCATE_STRUCT_MAP(NAME, Name, name) \
obj = AllocateMap(NAME##_TYPE, Name::kSize); \
if (obj->IsFailure()) return false; \
name##_map_ = Map::cast(obj);
STRUCT_LIST(ALLOCATE_STRUCT_MAP)
#undef ALLOCATE_STRUCT_MAP
obj = AllocateMap(FIXED_ARRAY_TYPE, HeapObject::kHeaderSize);
if (obj->IsFailure()) return false;
hash_table_map_ = Map::cast(obj);
obj = AllocateMap(FIXED_ARRAY_TYPE, HeapObject::kHeaderSize);
if (obj->IsFailure()) return false;
context_map_ = Map::cast(obj);
obj = AllocateMap(FIXED_ARRAY_TYPE, HeapObject::kHeaderSize);
if (obj->IsFailure()) return false;
global_context_map_ = Map::cast(obj);
obj = AllocateMap(JS_FUNCTION_TYPE, JSFunction::kSize);
if (obj->IsFailure()) return false;
boilerplate_function_map_ = Map::cast(obj);
obj = AllocateMap(SHARED_FUNCTION_INFO_TYPE, SharedFunctionInfo::kSize);
if (obj->IsFailure()) return false;
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);
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) {
// 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::CreateOddball(Map* map,
const char* to_string,
Object* to_number) {
Object* result = Allocate(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;
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));
message_listeners_ = JSObject::cast(obj);
obj = Heap::AllocateJSObjectFromMap(neander_map_);
if (obj->IsFailure()) return false;
elements = AllocateFixedArray(2);
if (elements->IsFailure()) return false;
FixedArray::cast(elements)->set(0, Smi::FromInt(0));
JSObject::cast(obj)->set_elements(FixedArray::cast(elements));
debug_event_listeners_ = JSObject::cast(obj);
return true;
}
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;
{
CEntryStub stub;
c_entry_code_ = *stub.GetCode();
}
{
CEntryDebugBreakStub stub;
c_entry_debug_break_code_ = *stub.GetCode();
}
{
JSEntryStub stub;
js_entry_code_ = *stub.GetCode();
}
{
JSConstructEntryStub stub;
js_construct_entry_code_ = *stub.GetCode();
}
}
bool Heap::CreateInitialObjects() {
Object* obj;
// The -0 value must be set before NumberFromDouble works.
obj = AllocateHeapNumber(-0.0, TENURED);
if (obj->IsFailure()) return false;
minus_zero_value_ = obj;
ASSERT(signbit(minus_zero_value_->Number()) != 0);
obj = AllocateHeapNumber(OS::nan_value(), TENURED);
if (obj->IsFailure()) return false;
nan_value_ = obj;
obj = Allocate(oddball_map(), OLD_DATA_SPACE);
if (obj->IsFailure()) return false;
undefined_value_ = obj;
ASSERT(!InNewSpace(undefined_value()));
// Allocate initial symbol table.
obj = SymbolTable::Allocate(kInitialSymbolTableSize);
if (obj->IsFailure()) return false;
symbol_table_ = 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_);
// Assign the print strings for oddballs after creating symboltable.
symbol = LookupAsciiSymbol("null");
if (symbol->IsFailure()) return false;
Oddball::cast(null_value_)->set_to_string(String::cast(symbol));
Oddball::cast(null_value_)->set_to_number(Smi::FromInt(0));
// Allocate the null_value
obj = Oddball::cast(null_value())->Initialize("null", Smi::FromInt(0));
if (obj->IsFailure()) return false;
obj = CreateOddball(oddball_map(), "true", Smi::FromInt(1));
if (obj->IsFailure()) return false;
true_value_ = obj;
obj = CreateOddball(oddball_map(), "false", Smi::FromInt(0));
if (obj->IsFailure()) return false;
false_value_ = obj;
obj = CreateOddball(oddball_map(), "hole", Smi::FromInt(-1));
if (obj->IsFailure()) return false;
the_hole_value_ = obj;
// Allocate the empty string.
obj = AllocateRawAsciiString(0, TENURED);
if (obj->IsFailure()) return false;
empty_string_ = String::cast(obj);
#define SYMBOL_INITIALIZE(name, string) \
obj = LookupAsciiSymbol(string); \
if (obj->IsFailure()) return false; \
(name##_) = String::cast(obj);
SYMBOL_LIST(SYMBOL_INITIALIZE)
#undef SYMBOL_INITIALIZE
// Allocate the proxy for __proto__.
obj = AllocateProxy((Address) &Accessors::ObjectPrototype);
if (obj->IsFailure()) return false;
prototype_accessors_ = Proxy::cast(obj);
// Allocate the code_stubs dictionary.
obj = Dictionary::Allocate(4);
if (obj->IsFailure()) return false;
code_stubs_ = Dictionary::cast(obj);
// Allocate the non_monomorphic_cache used in stub-cache.cc
obj = Dictionary::Allocate(4);
if (obj->IsFailure()) return false;
non_monomorphic_cache_ = Dictionary::cast(obj);
CreateFixedStubs();
// Allocate the number->string conversion cache
obj = AllocateFixedArray(kNumberStringCacheSize * 2);
if (obj->IsFailure()) return false;
number_string_cache_ = FixedArray::cast(obj);
// Allocate cache for single character strings.
obj = AllocateFixedArray(String::kMaxAsciiCharCode+1);
if (obj->IsFailure()) return false;
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;
natives_source_cache_ = FixedArray::cast(obj);
// Initialize compilation cache.
CompilationCache::Clear();
return true;
}
static inline int double_get_hash(double d) {
DoubleRepresentation rep(d);
return ((static_cast<int>(rep.bits) ^ static_cast<int>(rep.bits >> 32)) &
(Heap::kNumberStringCacheSize - 1));
}
static inline int smi_get_hash(Smi* smi) {
return (smi->value() & (Heap::kNumberStringCacheSize - 1));
}
Object* Heap::GetNumberStringCache(Object* number) {
int hash;
if (number->IsSmi()) {
hash = smi_get_hash(Smi::cast(number));
} else {
hash = double_get_hash(number->Number());
}
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;
if (number->IsSmi()) {
hash = smi_get_hash(Smi::cast(number));
number_string_cache_->set(hash * 2, number, FixedArray::SKIP_WRITE_BARRIER);
} else {
hash = double_get_hash(number->Number());
number_string_cache_->set(hash * 2, number);
}
number_string_cache_->set(hash * 2 + 1, string);
}
Object* Heap::SmiOrNumberFromDouble(double value,
bool new_object,
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 plus_zero(0.0);
static const DoubleRepresentation minus_zero(-0.0);
static const DoubleRepresentation nan(OS::nan_value());
ASSERT(minus_zero_value_ != NULL);
ASSERT(sizeof(plus_zero.value) == sizeof(plus_zero.bits));
DoubleRepresentation rep(value);
if (rep.bits == plus_zero.bits) return Smi::FromInt(0); // not uncommon
if (rep.bits == minus_zero.bits) {
return new_object ? AllocateHeapNumber(-0.0, pretenure)
: minus_zero_value_;
}
if (rep.bits == nan.bits) {
return new_object
? AllocateHeapNumber(OS::nan_value(), pretenure)
: nan_value_;
}
// Try to represent the value as a tagged small integer.
int int_value = FastD2I(value);
if (value == FastI2D(int_value) && Smi::IsValid(int_value)) {
return Smi::FromInt(int_value);
}
// Materialize the value in the heap.
return AllocateHeapNumber(value, pretenure);
}
Object* Heap::NewNumberFromDouble(double value, PretenureFlag pretenure) {
return SmiOrNumberFromDouble(value,
true /* number object must be new */,
pretenure);
}
Object* Heap::NumberFromDouble(double value, PretenureFlag pretenure) {
return SmiOrNumberFromDouble(value,
false /* use preallocated NaN, -0.0 */,
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(), NEW_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_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_lazy_load_data(undefined_value());
share->set_script(undefined_value());
share->set_start_position_and_type(0);
share->set_debug_info(undefined_value());
return result;
}
Object* Heap::AllocateConsString(String* first, String* second) {
int length = first->length() + second->length();
bool is_ascii = first->is_ascii_representation()
&& second->is_ascii_representation();
// If the resulting string is small make a flat string.
if (length < ConsString::kMinLength) {
Object* result = is_ascii
? AllocateRawAsciiString(length)
: AllocateRawTwoByteString(length);
if (result->IsFailure()) return result;
// Copy the characters into the new object.
String* string_result = String::cast(result);
int first_length = first->length();
// Copy the content of the first string.
for (int i = 0; i < first_length; i++) {
string_result->Set(i, first->Get(i));
}
int second_length = second->length();
// Copy the content of the first string.
for (int i = 0; i < second_length; i++) {
string_result->Set(first_length + i, second->Get(i));
}
return result;
}
Map* map;
if (length <= String::kMaxShortStringSize) {
map = is_ascii ? short_cons_ascii_string_map()
: short_cons_string_map();
} else if (length <= String::kMaxMediumStringSize) {
map = is_ascii ? medium_cons_ascii_string_map()
: medium_cons_string_map();
} else {
map = is_ascii ? long_cons_ascii_string_map()
: long_cons_string_map();
}
Object* result = Allocate(map, NEW_SPACE);
if (result->IsFailure()) return result;
ConsString* cons_string = ConsString::cast(result);
cons_string->set_first(first);
cons_string->set_second(second);
cons_string->set_length(length);
return result;
}
Object* Heap::AllocateSlicedString(String* buffer, int start, int end) {
int length = end - start;
// If the resulting string is small make a sub string.
if (end - start <= SlicedString::kMinLength) {
return Heap::AllocateSubString(buffer, start, end);
}
Map* map;
if (length <= String::kMaxShortStringSize) {
map = buffer->is_ascii_representation() ? short_sliced_ascii_string_map()
: short_sliced_string_map();
} else if (length <= String::kMaxMediumStringSize) {
map = buffer->is_ascii_representation() ? medium_sliced_ascii_string_map()
: medium_sliced_string_map();
} else {
map = buffer->is_ascii_representation() ? long_sliced_ascii_string_map()
: long_sliced_string_map();
}
Object* result = Allocate(map, NEW_SPACE);
if (result->IsFailure()) return result;
SlicedString* sliced_string = SlicedString::cast(result);
sliced_string->set_buffer(buffer);
sliced_string->set_start(start);
sliced_string->set_length(length);
return result;
}
Object* Heap::AllocateSubString(String* buffer, int start, int end) {
int length = end - start;
if (length == 1) {
return Heap::LookupSingleCharacterStringFromCode(buffer->Get(start));
}
// Make an attempt to flatten the buffer to reduce access time.
buffer->TryFlatten();
Object* result = buffer->is_ascii_representation()
? AllocateRawAsciiString(length)
: AllocateRawTwoByteString(length);
if (result->IsFailure()) return result;
// Copy the characters into the new object.
String* string_result = String::cast(result);
StringHasher hasher(length);
int i = 0;
for (; i < length && hasher.is_array_index(); i++) {
uc32 c = buffer->Get(start + i);
hasher.AddCharacter(c);
string_result->Set(i, c);
}
for (; i < length; i++) {
uc32 c = buffer->Get(start + i);
hasher.AddCharacterNoIndex(c);
string_result->Set(i, c);
}
string_result->set_length_field(hasher.GetHashField());
return result;
}
Object* Heap::AllocateExternalStringFromAscii(
ExternalAsciiString::Resource* resource) {
Map* map;
int length = resource->length();
if (length <= String::kMaxShortStringSize) {
map = short_external_ascii_string_map();
} else if (length <= String::kMaxMediumStringSize) {
map = medium_external_ascii_string_map();
} else {
map = long_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(length);
external_string->set_resource(resource);
return result;
}
Object* Heap::AllocateExternalStringFromTwoByte(
ExternalTwoByteString::Resource* resource) {
Map* map;
int length = resource->length();
if (length <= String::kMaxShortStringSize) {
map = short_external_string_map();
} else if (length <= String::kMaxMediumStringSize) {
map = medium_external_string_map();
} else {
map = long_external_string_map();
}
Object* result = Allocate(map, NEW_SPACE);
if (result->IsFailure()) return result;
ExternalTwoByteString* external_string = ExternalTwoByteString::cast(result);
external_string->set_length(length);
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::cast(result)->Set(0, code);
return result;
}
Object* Heap::AllocateByteArray(int length) {
int size = ByteArray::SizeFor(length);
AllocationSpace space =
size > MaxHeapObjectSize() ? LO_SPACE : NEW_SPACE;
Object* result = AllocateRaw(size, space);
if (result->IsFailure()) return result;
reinterpret_cast<Array*>(result)->set_map(byte_array_map());
reinterpret_cast<Array*>(result)->set_length(length);
return result;
}
Object* Heap::CreateCode(const CodeDesc& desc,
ScopeInfo<>* sinfo,
Code::Flags flags) {
// Compute size
int body_size = RoundUp(desc.instr_size + desc.reloc_size, kObjectAlignment);
int sinfo_size = 0;
if (sinfo != NULL) sinfo_size = sinfo->Serialize(NULL);
int obj_size = Code::SizeFor(body_size, sinfo_size);
Object* result;
if (obj_size > MaxHeapObjectSize()) {
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);
code->set_instruction_size(desc.instr_size);
code->set_relocation_size(desc.reloc_size);
code->set_sinfo_size(sinfo_size);
code->set_flags(flags);
code->set_ic_flag(Code::IC_TARGET_IS_ADDRESS);
code->CopyFrom(desc); // migrate generated code
if (sinfo != NULL) sinfo->Serialize(code); // write scope info
#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 > MaxHeapObjectSize()) {
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(reinterpret_cast<Object**>(new_addr),
reinterpret_cast<Object**>(old_addr),
obj_size);
// Relocate the copy.
Code* new_code = Code::cast(result);
new_code->Relocate(new_addr - old_addr);
return new_code;
}
Object* Heap::Allocate(Map* map, AllocationSpace space) {
ASSERT(gc_state_ == NOT_IN_GC);
ASSERT(map->instance_type() != MAP_TYPE);
Object* result = AllocateRaw(map->instance_size(), space);
if (result->IsFailure()) return result;
HeapObject::cast(result)->set_map(map);
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_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.
Object* prototype =
AllocateJSObject(Top::context()->global_context()->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) {
Object* result = Allocate(function_map, OLD_POINTER_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();
Object* result = CopyJSObject(boilerplate);
if (result->IsFailure()) return result;
Object* obj = JSObject::cast(result)->properties();
FixedArray::cast(obj)->set(arguments_callee_index, callee);
FixedArray::cast(obj)->set(arguments_length_index, Smi::FromInt(length));
// Allocate the fixed array.
obj = Heap::AllocateFixedArray(length);
if (obj->IsFailure()) return obj;
JSObject::cast(result)->set_elements(FixedArray::cast(obj));
// Check the state of the object
ASSERT(JSObject::cast(result)->HasFastProperties());
ASSERT(JSObject::cast(result)->HasFastElements());
return result;
}
Object* Heap::AllocateInitialMap(JSFunction* fun) {
ASSERT(!fun->has_initial_map());
// First create a new map with the expected number of properties being
// allocated in-object.
int expected_nof_properties = fun->shared()->expected_nof_properties();
int instance_size = JSObject::kHeaderSize +
expected_nof_properties * kPointerSize;
if (instance_size > JSObject::kMaxInstanceSize) {
instance_size = JSObject::kMaxInstanceSize;
expected_nof_properties = (instance_size - JSObject::kHeaderSize) /
kPointerSize;
}
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(expected_nof_properties);
map->set_unused_property_fields(expected_nof_properties);
map->set_prototype(prototype);
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).
obj->InitializeBody(map->instance_size());
}
Object* Heap::AllocateJSObjectFromMap(Map* map, PretenureFlag pretenure) {
// JSFunctions should be allocated using AllocateFunction to be
// properly initialized.
ASSERT(map->instance_type() != JS_FUNCTION_TYPE);
// Allocate the backing storage for the properties.
int prop_size = map->unused_property_fields() - map->inobject_properties();
Object* properties = AllocateFixedArray(prop_size);
if (properties->IsFailure()) return properties;
// Allocate the JSObject.
AllocationSpace space =
(pretenure == TENURED) ? OLD_POINTER_SPACE : NEW_SPACE;
if (map->instance_size() > MaxHeapObjectSize()) space = LO_SPACE;
Object* obj = Allocate(map, space);
if (obj->IsFailure()) return obj;
// Initialize the JSObject.
InitializeJSObjectFromMap(JSObject::cast(obj),
FixedArray::cast(properties),
map);
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.
return AllocateJSObjectFromMap(constructor->initial_map(), pretenure);
}
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 = new_space_.AllocateRaw(object_size);
if (clone->IsFailure()) return clone;
ASSERT(Heap::InNewSpace(clone));
// Copy the content.
CopyBlock(reinterpret_cast<Object**>(HeapObject::cast(clone)->address()),
reinterpret_cast<Object**>(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 = Heap::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 = Heap::CopyFixedArray(properties);
if (prop->IsFailure()) return prop;
JSObject::cast(clone)->set_properties(FixedArray::cast(prop));
}
// Return the new clone.
return clone;
}
Object* Heap::ReinitializeJSGlobalProxy(JSFunction* constructor,
JSGlobalProxy* object) {
// Allocate 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);
}
Map* map = constructor->initial_map();
// Check that the already allocated object has the same size as
// objects allocated using the constructor.
ASSERT(map->instance_size() == object->map()->instance_size());
// Allocate the backing storage for the properties.
int prop_size = map->unused_property_fields() - map->inobject_properties();
Object* properties = AllocateFixedArray(prop_size);
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) {
// 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();
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 == short_ascii_string_map()) return short_ascii_symbol_map();
if (map == medium_ascii_string_map()) return medium_ascii_symbol_map();
if (map == long_ascii_string_map()) return long_ascii_symbol_map();
if (map == short_string_map()) return short_symbol_map();
if (map == medium_string_map()) return medium_symbol_map();
if (map == long_string_map()) return long_symbol_map();
if (map == short_cons_string_map()) return short_cons_symbol_map();
if (map == medium_cons_string_map()) return medium_cons_symbol_map();
if (map == long_cons_string_map()) return long_cons_symbol_map();
if (map == short_cons_ascii_string_map()) {
return short_cons_ascii_symbol_map();
}
if (map == medium_cons_ascii_string_map()) {
return medium_cons_ascii_symbol_map();
}
if (map == long_cons_ascii_string_map()) {
return long_cons_ascii_symbol_map();
}
if (map == short_sliced_string_map()) return short_sliced_symbol_map();
if (map == medium_sliced_string_map()) return short_sliced_symbol_map();
if (map == long_sliced_string_map()) return short_sliced_symbol_map();
if (map == short_sliced_ascii_string_map()) {
return short_sliced_ascii_symbol_map();
}
if (map == medium_sliced_ascii_string_map()) {
return short_sliced_ascii_symbol_map();
}
if (map == long_sliced_ascii_string_map()) {
return short_sliced_ascii_symbol_map();
}
if (map == short_external_string_map()) return short_external_string_map();
if (map == medium_external_string_map()) return medium_external_string_map();
if (map == long_external_string_map()) return long_external_string_map();
if (map == short_external_ascii_string_map()) {
return short_external_ascii_string_map();
}
if (map == medium_external_ascii_string_map()) {
return medium_external_ascii_string_map();
}
if (map == long_external_ascii_string_map()) {
return long_external_ascii_string_map();
}
// No match found.
return NULL;
}
Object* Heap::AllocateSymbol(unibrow::CharacterStream* buffer,
int chars,
uint32_t length_field) {
// 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;
}
buffer->Rewind();
// Compute map and object size.
int size;
Map* map;
if (is_ascii) {
if (chars <= String::kMaxShortStringSize) {
map = short_ascii_symbol_map();
} else if (chars <= String::kMaxMediumStringSize) {
map = medium_ascii_symbol_map();
} else {
map = long_ascii_symbol_map();
}
size = SeqAsciiString::SizeFor(chars);
} else {
if (chars <= String::kMaxShortStringSize) {
map = short_symbol_map();
} else if (chars <= String::kMaxMediumStringSize) {
map = medium_symbol_map();
} else {
map = long_symbol_map();
}
size = SeqTwoByteString::SizeFor(chars);
}
// Allocate string.
AllocationSpace space =
(size > MaxHeapObjectSize()) ? LO_SPACE : OLD_DATA_SPACE;
Object* result = AllocateRaw(size, space);
if (result->IsFailure()) return result;
reinterpret_cast<HeapObject*>(result)->set_map(map);
// The hash value contains the length of the string.
String::cast(result)->set_length_field(length_field);
ASSERT_EQ(size, String::cast(result)->Size());
// Fill in the characters.
for (int i = 0; i < chars; i++) {
String::cast(result)->Set(i, buffer->GetNext());
}
return result;
}
Object* Heap::AllocateRawAsciiString(int length, PretenureFlag pretenure) {
AllocationSpace space = (pretenure == TENURED) ? OLD_DATA_SPACE : NEW_SPACE;
int size = SeqAsciiString::SizeFor(length);
if (size > MaxHeapObjectSize()) {
space = LO_SPACE;
}
// Use AllocateRaw rather than Allocate because the object's size cannot be
// determined from the map.
Object* result = AllocateRaw(size, space);
if (result->IsFailure()) return result;
// Determine the map based on the string's length.
Map* map;
if (length <= String::kMaxShortStringSize) {
map = short_ascii_string_map();
} else if (length <= String::kMaxMediumStringSize) {
map = medium_ascii_string_map();
} else {
map = long_ascii_string_map();
}
// Partially initialize the object.
HeapObject::cast(result)->set_map(map);
String::cast(result)->set_length(length);
ASSERT_EQ(size, HeapObject::cast(result)->Size());
return result;
}
Object* Heap::AllocateRawTwoByteString(int length, PretenureFlag pretenure) {
AllocationSpace space = (pretenure == TENURED) ? OLD_DATA_SPACE : NEW_SPACE;
int size = SeqTwoByteString::SizeFor(length);
if (size > MaxHeapObjectSize()) {
space = LO_SPACE;
}
// Use AllocateRaw rather than Allocate because the object's size cannot be
// determined from the map.
Object* result = AllocateRaw(size, space);
if (result->IsFailure()) return result;
// Determine the map based on the string's length.
Map* map;
if (length <= String::kMaxShortStringSize) {
map = short_string_map();
} else if (length <= String::kMaxMediumStringSize) {
map = medium_string_map();
} else {
map = long_string_map();
}
// Partially initialize the object.
HeapObject::cast(result)->set_map(map);
String::cast(result)->set_length(length);
ASSERT_EQ(size, HeapObject::cast(result)->Size());
return result;
}
Object* Heap::AllocateEmptyFixedArray() {
int size = FixedArray::SizeFor(0);
Object* result = AllocateRaw(size, OLD_DATA_SPACE);
if (result->IsFailure()) return result;
// Initialize the object.
reinterpret_cast<Array*>(result)->set_map(fixed_array_map());
reinterpret_cast<Array*>(result)->set_length(0);
return result;
}
Object* Heap::AllocateRawFixedArray(int length) {
// Allocate the raw data for a fixed array.
int size = FixedArray::SizeFor(length);
return (size > MaxHeapObjectSize())
? lo_space_->AllocateRawFixedArray(size)
: new_space_.AllocateRaw(size);
}
Object* Heap::CopyFixedArray(FixedArray* src) {
int len = src->length();
Object* obj = AllocateRawFixedArray(len);
if (obj->IsFailure()) return obj;
if (Heap::InNewSpace(obj)) {
HeapObject* dst = HeapObject::cast(obj);
CopyBlock(reinterpret_cast<Object**>(dst->address()),
reinterpret_cast<Object**>(src->address()),
FixedArray::SizeFor(len));
return obj;
}
HeapObject::cast(obj)->set_map(src->map());
FixedArray* result = FixedArray::cast(obj);
result->set_length(len);
// Copy the content
for (int i = 0; i < len; i++) result->set(i, src->get(i));
return result;
}
Object* Heap::AllocateFixedArray(int length) {
Object* result = AllocateRawFixedArray(length);
if (!result->IsFailure()) {
// Initialize header.
reinterpret_cast<Array*>(result)->set_map(fixed_array_map());
FixedArray* array = FixedArray::cast(result);
array->set_length(length);
// Initialize body.
for (int index = 0; index < length; index++) array->set_undefined(index);
}
return result;
}
Object* Heap::AllocateFixedArray(int length, PretenureFlag pretenure) {
ASSERT(empty_fixed_array()->IsFixedArray());
if (length == 0) return empty_fixed_array();
int size = FixedArray::SizeFor(length);
Object* result;
if (size > MaxHeapObjectSize()) {
result = lo_space_->AllocateRawFixedArray(size);
} else {
AllocationSpace space =
(pretenure == TENURED) ? OLD_POINTER_SPACE : NEW_SPACE;
result = AllocateRaw(size, space);
}
if (result->IsFailure()) return result;
// Initialize the object.
reinterpret_cast<Array*>(result)->set_map(fixed_array_map());
FixedArray* array = FixedArray::cast(result);
array->set_length(length);
for (int index = 0; index < length; index++) array->set_undefined(index);
return array;
}
Object* Heap::AllocateFixedArrayWithHoles(int length) {
if (length == 0) return empty_fixed_array();
Object* result = AllocateRawFixedArray(length);
if (!result->IsFailure()) {
// Initialize header.
reinterpret_cast<Array*>(result)->set_map(fixed_array_map());
FixedArray* array = FixedArray::cast(result);
array->set_length(length);
// Initialize body.
for (int index = 0; index < length; index++) array->set_the_hole(index);
}
return result;
}
Object* Heap::AllocateHashTable(int length) {
Object* result = Heap::AllocateFixedArray(length);
if (result->IsFailure()) return result;
reinterpret_cast<Array*>(result)->set_map(hash_table_map());
ASSERT(result->IsDictionary());
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) {
Object* result = Heap::AllocateFixedArray(Context::MIN_CONTEXT_SLOTS);
if (result->IsFailure()) return result;
Context* context = reinterpret_cast<Context*>(result);
context->set_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 > MaxHeapObjectSize()) ? LO_SPACE : OLD_POINTER_SPACE;
Object* result = Heap::Allocate(map, space);
if (result->IsFailure()) return result;
Struct::cast(result)->InitializeBody(size);
return result;
}
#ifdef DEBUG
void Heap::Print() {
if (!HasBeenSetup()) return;
Top::PrintStack();
AllSpaces spaces;
while (Space* 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("promoted_space_limit_ %d\n", promoted_space_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("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) ||
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 LO_SPACE:
return lo_space_->SlowContains(addr);
}
return false;
}
#ifdef DEBUG
void Heap::Verify() {
ASSERT(HasBeenSetup());
VerifyPointersVisitor visitor;
Heap::IterateRoots(&visitor);
AllSpaces spaces;
while (Space* space = spaces.next()) {
space->Verify();
}
}
#endif // DEBUG
Object* Heap::LookupSymbol(Vector<const char> string) {
Object* symbol = NULL;
Object* new_table =
SymbolTable::cast(symbol_table_)->LookupSymbol(string, &symbol);
if (new_table->IsFailure()) return new_table;
symbol_table_ = new_table;
ASSERT(symbol != NULL);
return symbol;
}
Object* Heap::LookupSymbol(String* string) {
if (string->IsSymbol()) return string;
Object* symbol = NULL;
Object* new_table =
SymbolTable::cast(symbol_table_)->LookupString(string, &symbol);
if (new_table->IsFailure()) return new_table;
symbol_table_ = new_table;
ASSERT(symbol != NULL);
return symbol;
}
bool Heap::LookupSymbolIfExists(String* string, String** symbol) {
if (string->IsSymbol()) {
*symbol = string;
return true;
}
SymbolTable* table = SymbolTable::cast(symbol_table_);
return table->LookupSymbolIfExists(string, symbol);
}
#ifdef DEBUG
void Heap::ZapFromSpace() {
ASSERT(HAS_HEAP_OBJECT_TAG(kFromSpaceZapValue));
for (Address a = new_space_.FromSpaceLow();
a < new_space_.FromSpaceHigh();
a += kPointerSize) {
Memory::Address_at(a) = kFromSpaceZapValue;
}
}
#endif // DEBUG
void Heap::IterateRSetRange(Address object_start,
Address object_end,
Address rset_start,
ObjectSlotCallback copy_object_func) {
Address object_address = object_start;
Address rset_address = rset_start;
// Loop over all the pointers in [object_start, object_end).
while (object_address < object_end) {
uint32_t rset_word = Memory::uint32_at(rset_address);
if (rset_word != 0) {
uint32_t result_rset = rset_word;
for (uint32_t bitmask = 1; bitmask != 0; bitmask = bitmask << 1) {
// Do not dereference pointers at or past object_end.
if ((rset_word & bitmask) != 0 && object_address < object_end) {
Object** object_p = reinterpret_cast<Object**>(object_address);
if (Heap::InNewSpace(*object_p)) {
copy_object_func(reinterpret_cast<HeapObject**>(object_p));
}
// If this pointer does not need to be remembered anymore, clear
// the remembered set bit.
if (!Heap::InNewSpace(*object_p)) result_rset &= ~bitmask;
}
object_address += kPointerSize;
}
// Update the remembered set if it has changed.
if (result_rset != rset_word) {
Memory::uint32_at(rset_address) = result_rset;
}
} else {
// No bits in the word were set. This is the common case.
object_address += kPointerSize * kBitsPerInt;
}
rset_address += kIntSize;
}
}
void Heap::IterateRSet(PagedSpace* space, ObjectSlotCallback copy_object_func) {
ASSERT(Page::is_rset_in_use());
ASSERT(space == old_pointer_space_ || space == map_space_);
PageIterator it(space, PageIterator::PAGES_IN_USE);
while (it.has_next()) {
Page* page = it.next();
IterateRSetRange(page->ObjectAreaStart(), page->AllocationTop(),
page->RSetStart(), copy_object_func);
}
}
#ifdef DEBUG
#define SYNCHRONIZE_TAG(tag) v->Synchronize(tag)
#else
#define SYNCHRONIZE_TAG(tag)
#endif
void Heap::IterateRoots(ObjectVisitor* v) {
IterateStrongRoots(v);
v->VisitPointer(reinterpret_cast<Object**>(&symbol_table_));
SYNCHRONIZE_TAG("symbol_table");
}
void Heap::IterateStrongRoots(ObjectVisitor* v) {
#define ROOT_ITERATE(type, name) \
v->VisitPointer(bit_cast<Object**, type**>(&name##_));
STRONG_ROOT_LIST(ROOT_ITERATE);
#undef ROOT_ITERATE
SYNCHRONIZE_TAG("strong_root_list");
#define STRUCT_MAP_ITERATE(NAME, Name, name) \
v->VisitPointer(bit_cast<Object**, Map**>(&name##_map_));
STRUCT_LIST(STRUCT_MAP_ITERATE);
#undef STRUCT_MAP_ITERATE
SYNCHRONIZE_TAG("struct_map");
#define SYMBOL_ITERATE(name, string) \
v->VisitPointer(bit_cast<Object**, String**>(&name##_));
SYMBOL_LIST(SYMBOL_ITERATE)
#undef SYMBOL_ITERATE
SYNCHRONIZE_TAG("symbol");
Bootstrapper::Iterate(v);
SYNCHRONIZE_TAG("bootstrapper");
Top::Iterate(v);
SYNCHRONIZE_TAG("top");
Debug::Iterate(v);
SYNCHRONIZE_TAG("debug");
CompilationCache::Iterate(v);
SYNCHRONIZE_TAG("compilationcache");
// Iterate over local handles in handle scopes.
HandleScopeImplementer::Iterate(v);
SYNCHRONIZE_TAG("handlescope");
// Iterate over the builtin code objects and code stubs in the heap. Note
// that it is not strictly necessary to iterate over code objects on
// scavenge collections. We still do it here because this same function
// is used by the mark-sweep collector and the deserializer.
Builtins::IterateBuiltins(v);
SYNCHRONIZE_TAG("builtins");
// Iterate over global handles.
GlobalHandles::IterateRoots(v);
SYNCHRONIZE_TAG("globalhandles");
// Iterate over pointers being held by inactive threads.
ThreadManager::Iterate(v);
SYNCHRONIZE_TAG("threadmanager");
}
#undef SYNCHRONIZE_TAG
// 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 semispace_size, int old_gen_size) {
if (HasBeenSetup()) return false;
if (semispace_size > 0) semispace_size_ = semispace_size;
if (old_gen_size > 0) old_generation_size_ = old_gen_size;
// The new space size must be a power of two to support single-bit testing
// for containment.
semispace_size_ = RoundUpToPowerOf2(semispace_size_);
initial_semispace_size_ = Min(initial_semispace_size_, semispace_size_);
young_generation_size_ = 2 * semispace_size_;
// The old generation is paged.
old_generation_size_ = RoundUp(old_generation_size_, Page::kPageSize);
heap_configured = true;
return true;
}
bool Heap::ConfigureHeapDefault() {
return ConfigureHeap(FLAG_new_space_size, FLAG_old_space_size);
}
int Heap::PromotedSpaceSize() {
return old_pointer_space_->Size()
+ old_data_space_->Size()
+ code_space_->Size()
+ map_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;
}
// Setup memory allocator and allocate an initial chunk of memory. The
// initial chunk is double the size of the new space to ensure that we can
// find a pair of semispaces that are contiguous and aligned to their size.
if (!MemoryAllocator::Setup(MaxCapacity())) return false;
void* chunk
= MemoryAllocator::ReserveInitialChunk(2 * young_generation_size_);
if (chunk == NULL) return false;
// Put the initial chunk of the old space at the start of the initial
// chunk, then the two new space semispaces, then the initial chunk of
// code space. Align the pair of semispaces to their size, which must be
// a power of 2.
ASSERT(IsPowerOf2(young_generation_size_));
Address code_space_start = reinterpret_cast<Address>(chunk);
Address new_space_start = RoundUp(code_space_start, young_generation_size_);
Address old_space_start = new_space_start + young_generation_size_;
int code_space_size = new_space_start - code_space_start;
int old_space_size = young_generation_size_ - code_space_size;
// Initialize new space.
if (!new_space_.Setup(new_space_start, young_generation_size_)) return false;
// Initialize old space, set the maximum capacity to the old generation
// size. It will not contain code.
old_pointer_space_ =
new OldSpace(old_generation_size_, OLD_POINTER_SPACE, NOT_EXECUTABLE);
if (old_pointer_space_ == NULL) return false;
if (!old_pointer_space_->Setup(old_space_start, old_space_size >> 1)) {
return false;
}
old_data_space_ =
new OldSpace(old_generation_size_, OLD_DATA_SPACE, NOT_EXECUTABLE);
if (old_data_space_ == NULL) return false;
if (!old_data_space_->Setup(old_space_start + (old_space_size >> 1),
old_space_size >> 1)) {
return false;
}
// Initialize the code space, set its maximum capacity to the old
// generation size. It needs executable memory.
code_space_ =
new OldSpace(old_generation_size_, CODE_SPACE, EXECUTABLE);
if (code_space_ == NULL) return false;
if (!code_space_->Setup(code_space_start, code_space_size)) return false;
// Initialize map space.
map_space_ = new MapSpace(kMaxMapSpaceSize, MAP_SPACE);
if (map_space_ == NULL) return false;
// Setting up a paged space without giving it a virtual memory range big
// enough to hold at least a page will cause it to allocate.
if (!map_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()));
return true;
}
void Heap::TearDown() {
GlobalHandles::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 (lo_space_ != NULL) {
lo_space_->TearDown();
delete lo_space_;
lo_space_ = NULL;
}
MemoryAllocator::TearDown();
}
void Heap::Shrink() {
// Try to shrink map, old, and code spaces.
map_space_->Shrink();
old_pointer_space_->Shrink();
old_data_space_->Shrink();
code_space_->Shrink();
}
#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 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();
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 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;
}
bool HeapIterator::has_next() {
// No iterator means we are done.
if (object_iterator_ == NULL) return false;
if (object_iterator_->has_next_object()) {
// If the current iterator has more objects we are fine.
return true;
} else {
// Go though the spaces looking for one that has objects.
while (space_iterator_->has_next()) {
object_iterator_ = space_iterator_->next();
if (object_iterator_->has_next_object()) {
return true;
}
}
}
// Done with the last space.
object_iterator_ = NULL;
return false;
}
HeapObject* HeapIterator::next() {
if (has_next()) {
return object_iterator_->next_object();
} else {
return NULL;
}
}
void HeapIterator::reset() {
// Restart the iterator.
Shutdown();
Init();
}
//
// HeapProfiler class implementation.
//
#ifdef ENABLE_LOGGING_AND_PROFILING
void HeapProfiler::CollectStats(HeapObject* obj, HistogramInfo* info) {
InstanceType type = obj->map()->instance_type();
ASSERT(0 <= type && type <= LAST_TYPE);
info[type].increment_number(1);
info[type].increment_bytes(obj->Size());
}
#endif
#ifdef ENABLE_LOGGING_AND_PROFILING
void HeapProfiler::WriteSample() {
LOG(HeapSampleBeginEvent("Heap", "allocated"));
HistogramInfo info[LAST_TYPE+1];
#define DEF_TYPE_NAME(name) info[name].set_name(#name);
INSTANCE_TYPE_LIST(DEF_TYPE_NAME)
#undef DEF_TYPE_NAME
HeapIterator iterator;
while (iterator.has_next()) {
CollectStats(iterator.next(), info);
}
// Lump all the string types together.
int string_number = 0;
int string_bytes = 0;
#define INCREMENT_SIZE(type, size, name) \
string_number += info[type].number(); \
string_bytes += info[type].bytes();
STRING_TYPE_LIST(INCREMENT_SIZE)
#undef INCREMENT_SIZE
if (string_bytes > 0) {
LOG(HeapSampleItemEvent("STRING_TYPE", string_number, string_bytes));
}
for (int i = FIRST_NONSTRING_TYPE; i <= LAST_TYPE; ++i) {
if (info[i].bytes() > 0) {
LOG(HeapSampleItemEvent(info[i].name(), info[i].number(),
info[i].bytes()));
}
}
LOG(HeapSampleEndEvent("Heap", "allocated"));
}
#endif
#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;
}
if (obj->IsCode()) {
Code::cast(obj)->ConvertICTargetsFromAddressToObject();
}
// 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);
if (obj->IsCode()) {
Code::cast(obj)->ConvertICTargetsFromObjectToAddress();
}
}
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() {
search_target = NULL;
search_for_any_global = false;
MarkRootVisitor root_visitor;
IterateRoots(&root_visitor);
}
// 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);
}
#endif
GCTracer::GCTracer()
: start_time_(0.0),
start_size_(0.0),
gc_count_(0),
full_gc_count_(0),
is_compacting_(false),
marked_count_(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) return;
start_time_ = OS::TimeCurrentMillis();
start_size_ = SizeOfHeapObjects();
}
GCTracer::~GCTracer() {
if (!FLAG_trace_gc) return;
// Printf ONE line iff flag is set.
PrintF("%s %.1f -> %.1f MB, %d ms.\n",
CollectorString(),
start_size_, SizeOfHeapObjects(),
static_cast<int>(OS::TimeCurrentMillis() - start_time_));
}
const char* GCTracer::CollectorString() {
switch (collector_) {
case SCAVENGER:
return "Scavenge";
case MARK_COMPACTOR:
return MarkCompactCollector::HasCompacted() ? "Mark-compact"
: "Mark-sweep";
}
return "Unknown GC";
}
#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
} } // namespace v8::internal
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