deps/v8/src/heap/objects-visiting-inl.h
// Copyright 2012 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef V8_OBJECTS_VISITING_INL_H_
#define V8_OBJECTS_VISITING_INL_H_
namespace v8 {
namespace internal {
template <typename StaticVisitor>
void StaticNewSpaceVisitor<StaticVisitor>::Initialize() {
table_.Register(
kVisitShortcutCandidate,
&FixedBodyVisitor<StaticVisitor, ConsString::BodyDescriptor, int>::Visit);
table_.Register(
kVisitConsString,
&FixedBodyVisitor<StaticVisitor, ConsString::BodyDescriptor, int>::Visit);
table_.Register(kVisitSlicedString,
&FixedBodyVisitor<StaticVisitor, SlicedString::BodyDescriptor,
int>::Visit);
table_.Register(
kVisitSymbol,
&FixedBodyVisitor<StaticVisitor, Symbol::BodyDescriptor, int>::Visit);
table_.Register(kVisitFixedArray,
&FlexibleBodyVisitor<StaticVisitor,
FixedArray::BodyDescriptor, int>::Visit);
table_.Register(kVisitFixedDoubleArray, &VisitFixedDoubleArray);
table_.Register(kVisitFixedTypedArray, &VisitFixedTypedArray);
table_.Register(kVisitFixedFloat64Array, &VisitFixedTypedArray);
table_.Register(
kVisitNativeContext,
&FixedBodyVisitor<StaticVisitor, Context::ScavengeBodyDescriptor,
int>::Visit);
table_.Register(kVisitByteArray, &VisitByteArray);
table_.Register(
kVisitSharedFunctionInfo,
&FixedBodyVisitor<StaticVisitor, SharedFunctionInfo::BodyDescriptor,
int>::Visit);
table_.Register(kVisitSeqOneByteString, &VisitSeqOneByteString);
table_.Register(kVisitSeqTwoByteString, &VisitSeqTwoByteString);
table_.Register(kVisitJSFunction, &VisitJSFunction);
table_.Register(kVisitJSArrayBuffer, &VisitJSArrayBuffer);
table_.Register(kVisitJSTypedArray, &VisitJSTypedArray);
table_.Register(kVisitJSDataView, &VisitJSDataView);
table_.Register(kVisitFreeSpace, &VisitFreeSpace);
table_.Register(kVisitJSWeakCollection, &JSObjectVisitor::Visit);
table_.Register(kVisitJSRegExp, &JSObjectVisitor::Visit);
table_.template RegisterSpecializations<DataObjectVisitor, kVisitDataObject,
kVisitDataObjectGeneric>();
table_.template RegisterSpecializations<JSObjectVisitor, kVisitJSObject,
kVisitJSObjectGeneric>();
table_.template RegisterSpecializations<StructVisitor, kVisitStruct,
kVisitStructGeneric>();
}
template <typename StaticVisitor>
int StaticNewSpaceVisitor<StaticVisitor>::VisitJSArrayBuffer(
Map* map, HeapObject* object) {
Heap* heap = map->GetHeap();
STATIC_ASSERT(JSArrayBuffer::kWeakFirstViewOffset ==
JSArrayBuffer::kWeakNextOffset + kPointerSize);
VisitPointers(heap, HeapObject::RawField(
object, JSArrayBuffer::BodyDescriptor::kStartOffset),
HeapObject::RawField(object, JSArrayBuffer::kWeakNextOffset));
VisitPointers(
heap, HeapObject::RawField(
object, JSArrayBuffer::kWeakNextOffset + 2 * kPointerSize),
HeapObject::RawField(object, JSArrayBuffer::kSizeWithInternalFields));
return JSArrayBuffer::kSizeWithInternalFields;
}
template <typename StaticVisitor>
int StaticNewSpaceVisitor<StaticVisitor>::VisitJSTypedArray(
Map* map, HeapObject* object) {
VisitPointers(
map->GetHeap(),
HeapObject::RawField(object, JSTypedArray::BodyDescriptor::kStartOffset),
HeapObject::RawField(object, JSTypedArray::kWeakNextOffset));
VisitPointers(
map->GetHeap(), HeapObject::RawField(
object, JSTypedArray::kWeakNextOffset + kPointerSize),
HeapObject::RawField(object, JSTypedArray::kSizeWithInternalFields));
return JSTypedArray::kSizeWithInternalFields;
}
template <typename StaticVisitor>
int StaticNewSpaceVisitor<StaticVisitor>::VisitJSDataView(Map* map,
HeapObject* object) {
VisitPointers(
map->GetHeap(),
HeapObject::RawField(object, JSDataView::BodyDescriptor::kStartOffset),
HeapObject::RawField(object, JSDataView::kWeakNextOffset));
VisitPointers(
map->GetHeap(),
HeapObject::RawField(object, JSDataView::kWeakNextOffset + kPointerSize),
HeapObject::RawField(object, JSDataView::kSizeWithInternalFields));
return JSDataView::kSizeWithInternalFields;
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::Initialize() {
table_.Register(kVisitShortcutCandidate,
&FixedBodyVisitor<StaticVisitor, ConsString::BodyDescriptor,
void>::Visit);
table_.Register(kVisitConsString,
&FixedBodyVisitor<StaticVisitor, ConsString::BodyDescriptor,
void>::Visit);
table_.Register(kVisitSlicedString,
&FixedBodyVisitor<StaticVisitor, SlicedString::BodyDescriptor,
void>::Visit);
table_.Register(
kVisitSymbol,
&FixedBodyVisitor<StaticVisitor, Symbol::BodyDescriptor, void>::Visit);
table_.Register(kVisitFixedArray, &FixedArrayVisitor::Visit);
table_.Register(kVisitFixedDoubleArray, &DataObjectVisitor::Visit);
table_.Register(kVisitFixedTypedArray, &DataObjectVisitor::Visit);
table_.Register(kVisitFixedFloat64Array, &DataObjectVisitor::Visit);
table_.Register(kVisitConstantPoolArray, &VisitConstantPoolArray);
table_.Register(kVisitNativeContext, &VisitNativeContext);
table_.Register(kVisitAllocationSite, &VisitAllocationSite);
table_.Register(kVisitByteArray, &DataObjectVisitor::Visit);
table_.Register(kVisitFreeSpace, &DataObjectVisitor::Visit);
table_.Register(kVisitSeqOneByteString, &DataObjectVisitor::Visit);
table_.Register(kVisitSeqTwoByteString, &DataObjectVisitor::Visit);
table_.Register(kVisitJSWeakCollection, &VisitWeakCollection);
table_.Register(
kVisitOddball,
&FixedBodyVisitor<StaticVisitor, Oddball::BodyDescriptor, void>::Visit);
table_.Register(kVisitMap, &VisitMap);
table_.Register(kVisitCode, &VisitCode);
table_.Register(kVisitSharedFunctionInfo, &VisitSharedFunctionInfo);
table_.Register(kVisitJSFunction, &VisitJSFunction);
table_.Register(kVisitJSArrayBuffer, &VisitJSArrayBuffer);
table_.Register(kVisitJSTypedArray, &VisitJSTypedArray);
table_.Register(kVisitJSDataView, &VisitJSDataView);
// Registration for kVisitJSRegExp is done by StaticVisitor.
table_.Register(
kVisitCell,
&FixedBodyVisitor<StaticVisitor, Cell::BodyDescriptor, void>::Visit);
table_.Register(kVisitPropertyCell, &VisitPropertyCell);
table_.template RegisterSpecializations<DataObjectVisitor, kVisitDataObject,
kVisitDataObjectGeneric>();
table_.template RegisterSpecializations<JSObjectVisitor, kVisitJSObject,
kVisitJSObjectGeneric>();
table_.template RegisterSpecializations<StructObjectVisitor, kVisitStruct,
kVisitStructGeneric>();
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitCodeEntry(
Heap* heap, Address entry_address) {
Code* code = Code::cast(Code::GetObjectFromEntryAddress(entry_address));
heap->mark_compact_collector()->RecordCodeEntrySlot(entry_address, code);
StaticVisitor::MarkObject(heap, code);
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitEmbeddedPointer(
Heap* heap, RelocInfo* rinfo) {
DCHECK(rinfo->rmode() == RelocInfo::EMBEDDED_OBJECT);
HeapObject* object = HeapObject::cast(rinfo->target_object());
heap->mark_compact_collector()->RecordRelocSlot(rinfo, object);
// TODO(ulan): It could be better to record slots only for strongly embedded
// objects here and record slots for weakly embedded object during clearing
// of non-live references in mark-compact.
if (!rinfo->host()->IsWeakObject(object)) {
StaticVisitor::MarkObject(heap, object);
}
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitCell(Heap* heap,
RelocInfo* rinfo) {
DCHECK(rinfo->rmode() == RelocInfo::CELL);
Cell* cell = rinfo->target_cell();
// No need to record slots because the cell space is not compacted during GC.
if (!rinfo->host()->IsWeakObject(cell)) {
StaticVisitor::MarkObject(heap, cell);
}
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitDebugTarget(Heap* heap,
RelocInfo* rinfo) {
DCHECK((RelocInfo::IsJSReturn(rinfo->rmode()) &&
rinfo->IsPatchedReturnSequence()) ||
(RelocInfo::IsDebugBreakSlot(rinfo->rmode()) &&
rinfo->IsPatchedDebugBreakSlotSequence()));
Code* target = Code::GetCodeFromTargetAddress(rinfo->call_address());
heap->mark_compact_collector()->RecordRelocSlot(rinfo, target);
StaticVisitor::MarkObject(heap, target);
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitCodeTarget(Heap* heap,
RelocInfo* rinfo) {
DCHECK(RelocInfo::IsCodeTarget(rinfo->rmode()));
Code* target = Code::GetCodeFromTargetAddress(rinfo->target_address());
// Monomorphic ICs are preserved when possible, but need to be flushed
// when they might be keeping a Context alive, or when the heap is about
// to be serialized.
if (FLAG_cleanup_code_caches_at_gc && target->is_inline_cache_stub() &&
(target->ic_state() == MEGAMORPHIC || target->ic_state() == GENERIC ||
target->ic_state() == POLYMORPHIC || heap->flush_monomorphic_ics() ||
heap->isolate()->serializer_enabled() ||
target->ic_age() != heap->global_ic_age() ||
target->is_invalidated_weak_stub())) {
IC::Clear(heap->isolate(), rinfo->pc(), rinfo->host()->constant_pool());
target = Code::GetCodeFromTargetAddress(rinfo->target_address());
}
heap->mark_compact_collector()->RecordRelocSlot(rinfo, target);
StaticVisitor::MarkObject(heap, target);
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitCodeAgeSequence(
Heap* heap, RelocInfo* rinfo) {
DCHECK(RelocInfo::IsCodeAgeSequence(rinfo->rmode()));
Code* target = rinfo->code_age_stub();
DCHECK(target != NULL);
heap->mark_compact_collector()->RecordRelocSlot(rinfo, target);
StaticVisitor::MarkObject(heap, target);
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitNativeContext(
Map* map, HeapObject* object) {
FixedBodyVisitor<StaticVisitor, Context::MarkCompactBodyDescriptor,
void>::Visit(map, object);
MarkCompactCollector* collector = map->GetHeap()->mark_compact_collector();
for (int idx = Context::FIRST_WEAK_SLOT; idx < Context::NATIVE_CONTEXT_SLOTS;
++idx) {
Object** slot = Context::cast(object)->RawFieldOfElementAt(idx);
collector->RecordSlot(slot, slot, *slot);
}
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitMap(Map* map,
HeapObject* object) {
Heap* heap = map->GetHeap();
Map* map_object = Map::cast(object);
// Clears the cache of ICs related to this map.
if (FLAG_cleanup_code_caches_at_gc) {
map_object->ClearCodeCache(heap);
}
// When map collection is enabled we have to mark through map's transitions
// and back pointers in a special way to make these links weak.
if (FLAG_collect_maps && map_object->CanTransition()) {
MarkMapContents(heap, map_object);
} else {
StaticVisitor::VisitPointers(
heap, HeapObject::RawField(object, Map::kPointerFieldsBeginOffset),
HeapObject::RawField(object, Map::kPointerFieldsEndOffset));
}
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitPropertyCell(
Map* map, HeapObject* object) {
Heap* heap = map->GetHeap();
Object** slot =
HeapObject::RawField(object, PropertyCell::kDependentCodeOffset);
if (FLAG_collect_maps) {
// Mark property cell dependent codes array but do not push it onto marking
// stack, this will make references from it weak. We will clean dead
// codes when we iterate over property cells in ClearNonLiveReferences.
HeapObject* obj = HeapObject::cast(*slot);
heap->mark_compact_collector()->RecordSlot(slot, slot, obj);
StaticVisitor::MarkObjectWithoutPush(heap, obj);
} else {
StaticVisitor::VisitPointer(heap, slot);
}
StaticVisitor::VisitPointers(
heap,
HeapObject::RawField(object, PropertyCell::kPointerFieldsBeginOffset),
HeapObject::RawField(object, PropertyCell::kPointerFieldsEndOffset));
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitAllocationSite(
Map* map, HeapObject* object) {
Heap* heap = map->GetHeap();
Object** slot =
HeapObject::RawField(object, AllocationSite::kDependentCodeOffset);
if (FLAG_collect_maps) {
// Mark allocation site dependent codes array but do not push it onto
// marking stack, this will make references from it weak. We will clean
// dead codes when we iterate over allocation sites in
// ClearNonLiveReferences.
HeapObject* obj = HeapObject::cast(*slot);
heap->mark_compact_collector()->RecordSlot(slot, slot, obj);
StaticVisitor::MarkObjectWithoutPush(heap, obj);
} else {
StaticVisitor::VisitPointer(heap, slot);
}
StaticVisitor::VisitPointers(
heap,
HeapObject::RawField(object, AllocationSite::kPointerFieldsBeginOffset),
HeapObject::RawField(object, AllocationSite::kPointerFieldsEndOffset));
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitWeakCollection(
Map* map, HeapObject* object) {
Heap* heap = map->GetHeap();
JSWeakCollection* weak_collection =
reinterpret_cast<JSWeakCollection*>(object);
// Enqueue weak collection in linked list of encountered weak collections.
if (weak_collection->next() == heap->undefined_value()) {
weak_collection->set_next(heap->encountered_weak_collections());
heap->set_encountered_weak_collections(weak_collection);
}
// Skip visiting the backing hash table containing the mappings and the
// pointer to the other enqueued weak collections, both are post-processed.
StaticVisitor::VisitPointers(
heap, HeapObject::RawField(object, JSWeakCollection::kPropertiesOffset),
HeapObject::RawField(object, JSWeakCollection::kTableOffset));
STATIC_ASSERT(JSWeakCollection::kTableOffset + kPointerSize ==
JSWeakCollection::kNextOffset);
STATIC_ASSERT(JSWeakCollection::kNextOffset + kPointerSize ==
JSWeakCollection::kSize);
// Partially initialized weak collection is enqueued, but table is ignored.
if (!weak_collection->table()->IsHashTable()) return;
// Mark the backing hash table without pushing it on the marking stack.
Object** slot = HeapObject::RawField(object, JSWeakCollection::kTableOffset);
HeapObject* obj = HeapObject::cast(*slot);
heap->mark_compact_collector()->RecordSlot(slot, slot, obj);
StaticVisitor::MarkObjectWithoutPush(heap, obj);
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitCode(Map* map,
HeapObject* object) {
Heap* heap = map->GetHeap();
Code* code = Code::cast(object);
if (FLAG_age_code && !heap->isolate()->serializer_enabled()) {
code->MakeOlder(heap->mark_compact_collector()->marking_parity());
}
code->CodeIterateBody<StaticVisitor>(heap);
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitSharedFunctionInfo(
Map* map, HeapObject* object) {
Heap* heap = map->GetHeap();
SharedFunctionInfo* shared = SharedFunctionInfo::cast(object);
if (shared->ic_age() != heap->global_ic_age()) {
shared->ResetForNewContext(heap->global_ic_age());
}
if (FLAG_cleanup_code_caches_at_gc) {
shared->ClearTypeFeedbackInfo();
}
if (FLAG_cache_optimized_code && FLAG_flush_optimized_code_cache &&
!shared->optimized_code_map()->IsSmi()) {
// Always flush the optimized code map if requested by flag.
shared->ClearOptimizedCodeMap();
}
MarkCompactCollector* collector = heap->mark_compact_collector();
if (collector->is_code_flushing_enabled()) {
if (FLAG_cache_optimized_code && !shared->optimized_code_map()->IsSmi()) {
// Add the shared function info holding an optimized code map to
// the code flusher for processing of code maps after marking.
collector->code_flusher()->AddOptimizedCodeMap(shared);
// Treat all references within the code map weakly by marking the
// code map itself but not pushing it onto the marking deque.
FixedArray* code_map = FixedArray::cast(shared->optimized_code_map());
StaticVisitor::MarkObjectWithoutPush(heap, code_map);
}
if (IsFlushable(heap, shared)) {
// This function's code looks flushable. But we have to postpone
// the decision until we see all functions that point to the same
// SharedFunctionInfo because some of them might be optimized.
// That would also make the non-optimized version of the code
// non-flushable, because it is required for bailing out from
// optimized code.
collector->code_flusher()->AddCandidate(shared);
// Treat the reference to the code object weakly.
VisitSharedFunctionInfoWeakCode(heap, object);
return;
}
} else {
if (FLAG_cache_optimized_code && !shared->optimized_code_map()->IsSmi()) {
// Flush optimized code map on major GCs without code flushing,
// needed because cached code doesn't contain breakpoints.
shared->ClearOptimizedCodeMap();
}
}
VisitSharedFunctionInfoStrongCode(heap, object);
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitConstantPoolArray(
Map* map, HeapObject* object) {
Heap* heap = map->GetHeap();
ConstantPoolArray* array = ConstantPoolArray::cast(object);
ConstantPoolArray::Iterator code_iter(array, ConstantPoolArray::CODE_PTR);
while (!code_iter.is_finished()) {
Address code_entry = reinterpret_cast<Address>(
array->RawFieldOfElementAt(code_iter.next_index()));
StaticVisitor::VisitCodeEntry(heap, code_entry);
}
ConstantPoolArray::Iterator heap_iter(array, ConstantPoolArray::HEAP_PTR);
while (!heap_iter.is_finished()) {
Object** slot = array->RawFieldOfElementAt(heap_iter.next_index());
HeapObject* object = HeapObject::cast(*slot);
heap->mark_compact_collector()->RecordSlot(slot, slot, object);
bool is_weak_object =
(array->get_weak_object_state() ==
ConstantPoolArray::WEAK_OBJECTS_IN_OPTIMIZED_CODE &&
Code::IsWeakObjectInOptimizedCode(object)) ||
(array->get_weak_object_state() ==
ConstantPoolArray::WEAK_OBJECTS_IN_IC &&
Code::IsWeakObjectInIC(object));
if (!is_weak_object) {
StaticVisitor::MarkObject(heap, object);
}
}
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitJSFunction(Map* map,
HeapObject* object) {
Heap* heap = map->GetHeap();
JSFunction* function = JSFunction::cast(object);
MarkCompactCollector* collector = heap->mark_compact_collector();
if (collector->is_code_flushing_enabled()) {
if (IsFlushable(heap, function)) {
// This function's code looks flushable. But we have to postpone
// the decision until we see all functions that point to the same
// SharedFunctionInfo because some of them might be optimized.
// That would also make the non-optimized version of the code
// non-flushable, because it is required for bailing out from
// optimized code.
collector->code_flusher()->AddCandidate(function);
// Visit shared function info immediately to avoid double checking
// of its flushability later. This is just an optimization because
// the shared function info would eventually be visited.
SharedFunctionInfo* shared = function->shared();
if (StaticVisitor::MarkObjectWithoutPush(heap, shared)) {
StaticVisitor::MarkObject(heap, shared->map());
VisitSharedFunctionInfoWeakCode(heap, shared);
}
// Treat the reference to the code object weakly.
VisitJSFunctionWeakCode(heap, object);
return;
} else {
// Visit all unoptimized code objects to prevent flushing them.
StaticVisitor::MarkObject(heap, function->shared()->code());
if (function->code()->kind() == Code::OPTIMIZED_FUNCTION) {
MarkInlinedFunctionsCode(heap, function->code());
}
}
}
VisitJSFunctionStrongCode(heap, object);
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitJSRegExp(Map* map,
HeapObject* object) {
int last_property_offset =
JSRegExp::kSize + kPointerSize * map->inobject_properties();
StaticVisitor::VisitPointers(
map->GetHeap(), HeapObject::RawField(object, JSRegExp::kPropertiesOffset),
HeapObject::RawField(object, last_property_offset));
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitJSArrayBuffer(
Map* map, HeapObject* object) {
Heap* heap = map->GetHeap();
STATIC_ASSERT(JSArrayBuffer::kWeakFirstViewOffset ==
JSArrayBuffer::kWeakNextOffset + kPointerSize);
StaticVisitor::VisitPointers(
heap,
HeapObject::RawField(object, JSArrayBuffer::BodyDescriptor::kStartOffset),
HeapObject::RawField(object, JSArrayBuffer::kWeakNextOffset));
StaticVisitor::VisitPointers(
heap, HeapObject::RawField(
object, JSArrayBuffer::kWeakNextOffset + 2 * kPointerSize),
HeapObject::RawField(object, JSArrayBuffer::kSizeWithInternalFields));
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitJSTypedArray(
Map* map, HeapObject* object) {
StaticVisitor::VisitPointers(
map->GetHeap(),
HeapObject::RawField(object, JSTypedArray::BodyDescriptor::kStartOffset),
HeapObject::RawField(object, JSTypedArray::kWeakNextOffset));
StaticVisitor::VisitPointers(
map->GetHeap(), HeapObject::RawField(
object, JSTypedArray::kWeakNextOffset + kPointerSize),
HeapObject::RawField(object, JSTypedArray::kSizeWithInternalFields));
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitJSDataView(Map* map,
HeapObject* object) {
StaticVisitor::VisitPointers(
map->GetHeap(),
HeapObject::RawField(object, JSDataView::BodyDescriptor::kStartOffset),
HeapObject::RawField(object, JSDataView::kWeakNextOffset));
StaticVisitor::VisitPointers(
map->GetHeap(),
HeapObject::RawField(object, JSDataView::kWeakNextOffset + kPointerSize),
HeapObject::RawField(object, JSDataView::kSizeWithInternalFields));
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::MarkMapContents(Heap* heap,
Map* map) {
// Make sure that the back pointer stored either in the map itself or
// inside its transitions array is marked. Skip recording the back
// pointer slot since map space is not compacted.
StaticVisitor::MarkObject(heap, HeapObject::cast(map->GetBackPointer()));
// Treat pointers in the transitions array as weak and also mark that
// array to prevent visiting it later. Skip recording the transition
// array slot, since it will be implicitly recorded when the pointer
// fields of this map are visited.
if (map->HasTransitionArray()) {
TransitionArray* transitions = map->transitions();
MarkTransitionArray(heap, transitions);
}
// Since descriptor arrays are potentially shared, ensure that only the
// descriptors that belong to this map are marked. The first time a
// non-empty descriptor array is marked, its header is also visited. The slot
// holding the descriptor array will be implicitly recorded when the pointer
// fields of this map are visited.
DescriptorArray* descriptors = map->instance_descriptors();
if (StaticVisitor::MarkObjectWithoutPush(heap, descriptors) &&
descriptors->length() > 0) {
StaticVisitor::VisitPointers(heap, descriptors->GetFirstElementAddress(),
descriptors->GetDescriptorEndSlot(0));
}
int start = 0;
int end = map->NumberOfOwnDescriptors();
if (start < end) {
StaticVisitor::VisitPointers(heap,
descriptors->GetDescriptorStartSlot(start),
descriptors->GetDescriptorEndSlot(end));
}
// Mark prototype dependent codes array but do not push it onto marking
// stack, this will make references from it weak. We will clean dead
// codes when we iterate over maps in ClearNonLiveTransitions.
Object** slot = HeapObject::RawField(map, Map::kDependentCodeOffset);
HeapObject* obj = HeapObject::cast(*slot);
heap->mark_compact_collector()->RecordSlot(slot, slot, obj);
StaticVisitor::MarkObjectWithoutPush(heap, obj);
// Mark the pointer fields of the Map. Since the transitions array has
// been marked already, it is fine that one of these fields contains a
// pointer to it.
StaticVisitor::VisitPointers(
heap, HeapObject::RawField(map, Map::kPointerFieldsBeginOffset),
HeapObject::RawField(map, Map::kPointerFieldsEndOffset));
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::MarkTransitionArray(
Heap* heap, TransitionArray* transitions) {
if (!StaticVisitor::MarkObjectWithoutPush(heap, transitions)) return;
// Simple transitions do not have keys nor prototype transitions.
if (transitions->IsSimpleTransition()) return;
if (transitions->HasPrototypeTransitions()) {
// Mark prototype transitions array but do not push it onto marking
// stack, this will make references from it weak. We will clean dead
// prototype transitions in ClearNonLiveTransitions.
Object** slot = transitions->GetPrototypeTransitionsSlot();
HeapObject* obj = HeapObject::cast(*slot);
heap->mark_compact_collector()->RecordSlot(slot, slot, obj);
StaticVisitor::MarkObjectWithoutPush(heap, obj);
}
for (int i = 0; i < transitions->number_of_transitions(); ++i) {
StaticVisitor::VisitPointer(heap, transitions->GetKeySlot(i));
}
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::MarkInlinedFunctionsCode(Heap* heap,
Code* code) {
// Skip in absence of inlining.
// TODO(turbofan): Revisit once we support inlining.
if (code->is_turbofanned()) return;
// For optimized functions we should retain both non-optimized version
// of its code and non-optimized version of all inlined functions.
// This is required to support bailing out from inlined code.
DeoptimizationInputData* data =
DeoptimizationInputData::cast(code->deoptimization_data());
FixedArray* literals = data->LiteralArray();
for (int i = 0, count = data->InlinedFunctionCount()->value(); i < count;
i++) {
JSFunction* inlined = JSFunction::cast(literals->get(i));
StaticVisitor::MarkObject(heap, inlined->shared()->code());
}
}
inline static bool IsValidNonBuiltinContext(Object* context) {
return context->IsContext() &&
!Context::cast(context)->global_object()->IsJSBuiltinsObject();
}
inline static bool HasSourceCode(Heap* heap, SharedFunctionInfo* info) {
Object* undefined = heap->undefined_value();
return (info->script() != undefined) &&
(reinterpret_cast<Script*>(info->script())->source() != undefined);
}
template <typename StaticVisitor>
bool StaticMarkingVisitor<StaticVisitor>::IsFlushable(Heap* heap,
JSFunction* function) {
SharedFunctionInfo* shared_info = function->shared();
// Code is either on stack, in compilation cache or referenced
// by optimized version of function.
MarkBit code_mark = Marking::MarkBitFrom(function->code());
if (code_mark.Get()) {
return false;
}
// The function must have a valid context and not be a builtin.
if (!IsValidNonBuiltinContext(function->context())) {
return false;
}
// We do not (yet) flush code for optimized functions.
if (function->code() != shared_info->code()) {
return false;
}
// Check age of optimized code.
if (FLAG_age_code && !function->code()->IsOld()) {
return false;
}
return IsFlushable(heap, shared_info);
}
template <typename StaticVisitor>
bool StaticMarkingVisitor<StaticVisitor>::IsFlushable(
Heap* heap, SharedFunctionInfo* shared_info) {
// Code is either on stack, in compilation cache or referenced
// by optimized version of function.
MarkBit code_mark = Marking::MarkBitFrom(shared_info->code());
if (code_mark.Get()) {
return false;
}
// The function must be compiled and have the source code available,
// to be able to recompile it in case we need the function again.
if (!(shared_info->is_compiled() && HasSourceCode(heap, shared_info))) {
return false;
}
// We never flush code for API functions.
Object* function_data = shared_info->function_data();
if (function_data->IsFunctionTemplateInfo()) {
return false;
}
// Only flush code for functions.
if (shared_info->code()->kind() != Code::FUNCTION) {
return false;
}
// Function must be lazy compilable.
if (!shared_info->allows_lazy_compilation()) {
return false;
}
// We do not (yet?) flush code for generator functions, because we don't know
// if there are still live activations (generator objects) on the heap.
if (shared_info->is_generator()) {
return false;
}
// If this is a full script wrapped in a function we do not flush the code.
if (shared_info->is_toplevel()) {
return false;
}
// If this is a function initialized with %SetCode then the one-to-one
// relation between SharedFunctionInfo and Code is broken.
if (shared_info->dont_flush()) {
return false;
}
// Check age of code. If code aging is disabled we never flush.
if (!FLAG_age_code || !shared_info->code()->IsOld()) {
return false;
}
return true;
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitSharedFunctionInfoStrongCode(
Heap* heap, HeapObject* object) {
Object** start_slot = HeapObject::RawField(
object, SharedFunctionInfo::BodyDescriptor::kStartOffset);
Object** end_slot = HeapObject::RawField(
object, SharedFunctionInfo::BodyDescriptor::kEndOffset);
StaticVisitor::VisitPointers(heap, start_slot, end_slot);
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitSharedFunctionInfoWeakCode(
Heap* heap, HeapObject* object) {
Object** name_slot =
HeapObject::RawField(object, SharedFunctionInfo::kNameOffset);
StaticVisitor::VisitPointer(heap, name_slot);
// Skip visiting kCodeOffset as it is treated weakly here.
STATIC_ASSERT(SharedFunctionInfo::kNameOffset + kPointerSize ==
SharedFunctionInfo::kCodeOffset);
STATIC_ASSERT(SharedFunctionInfo::kCodeOffset + kPointerSize ==
SharedFunctionInfo::kOptimizedCodeMapOffset);
Object** start_slot =
HeapObject::RawField(object, SharedFunctionInfo::kOptimizedCodeMapOffset);
Object** end_slot = HeapObject::RawField(
object, SharedFunctionInfo::BodyDescriptor::kEndOffset);
StaticVisitor::VisitPointers(heap, start_slot, end_slot);
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitJSFunctionStrongCode(
Heap* heap, HeapObject* object) {
Object** start_slot =
HeapObject::RawField(object, JSFunction::kPropertiesOffset);
Object** end_slot =
HeapObject::RawField(object, JSFunction::kCodeEntryOffset);
StaticVisitor::VisitPointers(heap, start_slot, end_slot);
VisitCodeEntry(heap, object->address() + JSFunction::kCodeEntryOffset);
STATIC_ASSERT(JSFunction::kCodeEntryOffset + kPointerSize ==
JSFunction::kPrototypeOrInitialMapOffset);
start_slot =
HeapObject::RawField(object, JSFunction::kPrototypeOrInitialMapOffset);
end_slot = HeapObject::RawField(object, JSFunction::kNonWeakFieldsEndOffset);
StaticVisitor::VisitPointers(heap, start_slot, end_slot);
}
template <typename StaticVisitor>
void StaticMarkingVisitor<StaticVisitor>::VisitJSFunctionWeakCode(
Heap* heap, HeapObject* object) {
Object** start_slot =
HeapObject::RawField(object, JSFunction::kPropertiesOffset);
Object** end_slot =
HeapObject::RawField(object, JSFunction::kCodeEntryOffset);
StaticVisitor::VisitPointers(heap, start_slot, end_slot);
// Skip visiting kCodeEntryOffset as it is treated weakly here.
STATIC_ASSERT(JSFunction::kCodeEntryOffset + kPointerSize ==
JSFunction::kPrototypeOrInitialMapOffset);
start_slot =
HeapObject::RawField(object, JSFunction::kPrototypeOrInitialMapOffset);
end_slot = HeapObject::RawField(object, JSFunction::kNonWeakFieldsEndOffset);
StaticVisitor::VisitPointers(heap, start_slot, end_slot);
}
void Code::CodeIterateBody(ObjectVisitor* v) {
int mode_mask = RelocInfo::kCodeTargetMask |
RelocInfo::ModeMask(RelocInfo::EMBEDDED_OBJECT) |
RelocInfo::ModeMask(RelocInfo::CELL) |
RelocInfo::ModeMask(RelocInfo::EXTERNAL_REFERENCE) |
RelocInfo::ModeMask(RelocInfo::JS_RETURN) |
RelocInfo::ModeMask(RelocInfo::DEBUG_BREAK_SLOT) |
RelocInfo::ModeMask(RelocInfo::RUNTIME_ENTRY);
// There are two places where we iterate code bodies: here and the
// templated CodeIterateBody (below). They should be kept in sync.
IteratePointer(v, kRelocationInfoOffset);
IteratePointer(v, kHandlerTableOffset);
IteratePointer(v, kDeoptimizationDataOffset);
IteratePointer(v, kTypeFeedbackInfoOffset);
IterateNextCodeLink(v, kNextCodeLinkOffset);
IteratePointer(v, kConstantPoolOffset);
RelocIterator it(this, mode_mask);
Isolate* isolate = this->GetIsolate();
for (; !it.done(); it.next()) {
it.rinfo()->Visit(isolate, v);
}
}
template <typename StaticVisitor>
void Code::CodeIterateBody(Heap* heap) {
int mode_mask = RelocInfo::kCodeTargetMask |
RelocInfo::ModeMask(RelocInfo::EMBEDDED_OBJECT) |
RelocInfo::ModeMask(RelocInfo::CELL) |
RelocInfo::ModeMask(RelocInfo::EXTERNAL_REFERENCE) |
RelocInfo::ModeMask(RelocInfo::JS_RETURN) |
RelocInfo::ModeMask(RelocInfo::DEBUG_BREAK_SLOT) |
RelocInfo::ModeMask(RelocInfo::RUNTIME_ENTRY);
// There are two places where we iterate code bodies: here and the non-
// templated CodeIterateBody (above). They should be kept in sync.
StaticVisitor::VisitPointer(
heap,
reinterpret_cast<Object**>(this->address() + kRelocationInfoOffset));
StaticVisitor::VisitPointer(
heap, reinterpret_cast<Object**>(this->address() + kHandlerTableOffset));
StaticVisitor::VisitPointer(
heap,
reinterpret_cast<Object**>(this->address() + kDeoptimizationDataOffset));
StaticVisitor::VisitPointer(
heap,
reinterpret_cast<Object**>(this->address() + kTypeFeedbackInfoOffset));
StaticVisitor::VisitNextCodeLink(
heap, reinterpret_cast<Object**>(this->address() + kNextCodeLinkOffset));
StaticVisitor::VisitPointer(
heap, reinterpret_cast<Object**>(this->address() + kConstantPoolOffset));
RelocIterator it(this, mode_mask);
for (; !it.done(); it.next()) {
it.rinfo()->template Visit<StaticVisitor>(heap);
}
}
}
} // namespace v8::internal
#endif // V8_OBJECTS_VISITING_INL_H_