| // Copyright 2017 the V8 project authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "src/objects/map-updater.h" |
| |
| #include "src/execution/isolate.h" |
| #include "src/handles/handles.h" |
| #include "src/objects/field-type.h" |
| #include "src/objects/objects-inl.h" |
| #include "src/objects/objects.h" |
| #include "src/objects/property-details.h" |
| #include "src/objects/transitions.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| namespace { |
| |
| inline bool EqualImmutableValues(Object obj1, Object obj2) { |
| if (obj1 == obj2) return true; // Valid for both kData and kAccessor kinds. |
| // TODO(ishell): compare AccessorPairs. |
| return false; |
| } |
| |
| } // namespace |
| |
| MapUpdater::MapUpdater(Isolate* isolate, Handle<Map> old_map) |
| : isolate_(isolate), |
| old_map_(old_map), |
| old_descriptors_(old_map->instance_descriptors(), isolate_), |
| old_nof_(old_map_->NumberOfOwnDescriptors()), |
| new_elements_kind_(old_map_->elements_kind()), |
| is_transitionable_fast_elements_kind_( |
| IsTransitionableFastElementsKind(new_elements_kind_)) { |
| // We shouldn't try to update remote objects. |
| DCHECK( |
| !old_map->FindRootMap(isolate).GetConstructor().IsFunctionTemplateInfo()); |
| } |
| |
| Name MapUpdater::GetKey(InternalIndex descriptor) const { |
| return old_descriptors_->GetKey(descriptor); |
| } |
| |
| PropertyDetails MapUpdater::GetDetails(InternalIndex descriptor) const { |
| DCHECK(descriptor.is_found()); |
| if (descriptor == modified_descriptor_) { |
| PropertyAttributes attributes = new_attributes_; |
| // If the original map was sealed or frozen, let us used the old |
| // attributes so that we follow the same transition path as before. |
| // Note that the user could not have changed the attributes because |
| // both seal and freeze make the properties non-configurable. |
| if (integrity_level_ == SEALED || integrity_level_ == FROZEN) { |
| attributes = old_descriptors_->GetDetails(descriptor).attributes(); |
| } |
| return PropertyDetails(new_kind_, attributes, new_location_, new_constness_, |
| new_representation_); |
| } |
| return old_descriptors_->GetDetails(descriptor); |
| } |
| |
| Object MapUpdater::GetValue(InternalIndex descriptor) const { |
| DCHECK(descriptor.is_found()); |
| if (descriptor == modified_descriptor_) { |
| DCHECK_EQ(kDescriptor, new_location_); |
| return *new_value_; |
| } |
| DCHECK_EQ(kDescriptor, GetDetails(descriptor).location()); |
| return old_descriptors_->GetStrongValue(descriptor); |
| } |
| |
| FieldType MapUpdater::GetFieldType(InternalIndex descriptor) const { |
| DCHECK(descriptor.is_found()); |
| if (descriptor == modified_descriptor_) { |
| DCHECK_EQ(kField, new_location_); |
| return *new_field_type_; |
| } |
| DCHECK_EQ(kField, GetDetails(descriptor).location()); |
| return old_descriptors_->GetFieldType(descriptor); |
| } |
| |
| Handle<FieldType> MapUpdater::GetOrComputeFieldType( |
| InternalIndex descriptor, PropertyLocation location, |
| Representation representation) const { |
| DCHECK(descriptor.is_found()); |
| // |location| is just a pre-fetched GetDetails(descriptor).location(). |
| DCHECK_EQ(location, GetDetails(descriptor).location()); |
| if (location == kField) { |
| return handle(GetFieldType(descriptor), isolate_); |
| } else { |
| return GetValue(descriptor).OptimalType(isolate_, representation); |
| } |
| } |
| |
| Handle<FieldType> MapUpdater::GetOrComputeFieldType( |
| Handle<DescriptorArray> descriptors, InternalIndex descriptor, |
| PropertyLocation location, Representation representation) { |
| // |location| is just a pre-fetched GetDetails(descriptor).location(). |
| DCHECK_EQ(descriptors->GetDetails(descriptor).location(), location); |
| if (location == kField) { |
| return handle(descriptors->GetFieldType(descriptor), isolate_); |
| } else { |
| return descriptors->GetStrongValue(descriptor) |
| .OptimalType(isolate_, representation); |
| } |
| } |
| |
| Handle<Map> MapUpdater::ReconfigureToDataField(InternalIndex descriptor, |
| PropertyAttributes attributes, |
| PropertyConstness constness, |
| Representation representation, |
| Handle<FieldType> field_type) { |
| DCHECK_EQ(kInitialized, state_); |
| DCHECK(descriptor.is_found()); |
| DCHECK(!old_map_->is_dictionary_map()); |
| modified_descriptor_ = descriptor; |
| new_kind_ = kData; |
| new_attributes_ = attributes; |
| new_location_ = kField; |
| |
| PropertyDetails old_details = |
| old_descriptors_->GetDetails(modified_descriptor_); |
| |
| // If property kind is not reconfigured merge the result with |
| // representation/field type from the old descriptor. |
| if (old_details.kind() == new_kind_) { |
| new_constness_ = GeneralizeConstness(constness, old_details.constness()); |
| |
| Representation old_representation = old_details.representation(); |
| new_representation_ = representation.generalize(old_representation); |
| |
| Handle<FieldType> old_field_type = |
| GetOrComputeFieldType(old_descriptors_, modified_descriptor_, |
| old_details.location(), new_representation_); |
| |
| new_field_type_ = |
| Map::GeneralizeFieldType(old_representation, old_field_type, |
| new_representation_, field_type, isolate_); |
| } else { |
| // We don't know if this is a first property kind reconfiguration |
| // and we don't know which value was in this property previously |
| // therefore we can't treat such a property as constant. |
| new_constness_ = PropertyConstness::kMutable; |
| new_representation_ = representation; |
| new_field_type_ = field_type; |
| } |
| |
| Map::GeneralizeIfCanHaveTransitionableFastElementsKind( |
| isolate_, old_map_->instance_type(), &new_representation_, |
| &new_field_type_); |
| |
| if (TryReconfigureToDataFieldInplace() == kEnd) return result_map_; |
| if (FindRootMap() == kEnd) return result_map_; |
| if (FindTargetMap() == kEnd) return result_map_; |
| if (ConstructNewMap() == kAtIntegrityLevelSource) { |
| ConstructNewMapWithIntegrityLevelTransition(); |
| } |
| DCHECK_EQ(kEnd, state_); |
| return result_map_; |
| } |
| |
| Handle<Map> MapUpdater::ReconfigureElementsKind(ElementsKind elements_kind) { |
| DCHECK_EQ(kInitialized, state_); |
| new_elements_kind_ = elements_kind; |
| is_transitionable_fast_elements_kind_ = |
| IsTransitionableFastElementsKind(new_elements_kind_); |
| |
| if (FindRootMap() == kEnd) return result_map_; |
| if (FindTargetMap() == kEnd) return result_map_; |
| if (ConstructNewMap() == kAtIntegrityLevelSource) { |
| ConstructNewMapWithIntegrityLevelTransition(); |
| } |
| DCHECK_EQ(kEnd, state_); |
| return result_map_; |
| } |
| |
| Handle<Map> MapUpdater::Update() { |
| DCHECK_EQ(kInitialized, state_); |
| DCHECK(old_map_->is_deprecated()); |
| |
| if (FindRootMap() == kEnd) return result_map_; |
| if (FindTargetMap() == kEnd) return result_map_; |
| if (ConstructNewMap() == kAtIntegrityLevelSource) { |
| ConstructNewMapWithIntegrityLevelTransition(); |
| } |
| DCHECK_EQ(kEnd, state_); |
| if (FLAG_fast_map_update) { |
| TransitionsAccessor(isolate_, old_map_).SetMigrationTarget(*result_map_); |
| } |
| return result_map_; |
| } |
| |
| void MapUpdater::GeneralizeField(Handle<Map> map, InternalIndex modify_index, |
| PropertyConstness new_constness, |
| Representation new_representation, |
| Handle<FieldType> new_field_type) { |
| Map::GeneralizeField(isolate_, map, modify_index, new_constness, |
| new_representation, new_field_type); |
| |
| DCHECK(*old_descriptors_ == old_map_->instance_descriptors() || |
| *old_descriptors_ == integrity_source_map_->instance_descriptors()); |
| } |
| |
| MapUpdater::State MapUpdater::Normalize(const char* reason) { |
| result_map_ = Map::Normalize(isolate_, old_map_, new_elements_kind_, |
| CLEAR_INOBJECT_PROPERTIES, reason); |
| state_ = kEnd; |
| return state_; // Done. |
| } |
| |
| MapUpdater::State MapUpdater::TryReconfigureToDataFieldInplace() { |
| // Updating deprecated maps in-place doesn't make sense. |
| if (old_map_->is_deprecated()) return state_; |
| |
| if (new_representation_.IsNone()) return state_; // Not done yet. |
| |
| PropertyDetails old_details = |
| old_descriptors_->GetDetails(modified_descriptor_); |
| Representation old_representation = old_details.representation(); |
| if (!old_representation.CanBeInPlaceChangedTo(new_representation_)) { |
| return state_; // Not done yet. |
| } |
| |
| DCHECK_EQ(new_kind_, old_details.kind()); |
| DCHECK_EQ(new_attributes_, old_details.attributes()); |
| DCHECK_EQ(kField, old_details.location()); |
| if (FLAG_trace_generalization) { |
| old_map_->PrintGeneralization( |
| isolate_, stdout, "uninitialized field", modified_descriptor_, old_nof_, |
| old_nof_, false, old_representation, new_representation_, |
| old_details.constness(), new_constness_, |
| handle(old_descriptors_->GetFieldType(modified_descriptor_), isolate_), |
| MaybeHandle<Object>(), new_field_type_, MaybeHandle<Object>()); |
| } |
| Handle<Map> field_owner( |
| old_map_->FindFieldOwner(isolate_, modified_descriptor_), isolate_); |
| |
| GeneralizeField(field_owner, modified_descriptor_, new_constness_, |
| new_representation_, new_field_type_); |
| // Check that the descriptor array was updated. |
| DCHECK(old_descriptors_->GetDetails(modified_descriptor_) |
| .representation() |
| .Equals(new_representation_)); |
| DCHECK(old_descriptors_->GetFieldType(modified_descriptor_) |
| .NowIs(new_field_type_)); |
| |
| result_map_ = old_map_; |
| state_ = kEnd; |
| return state_; // Done. |
| } |
| |
| bool MapUpdater::TrySaveIntegrityLevelTransitions() { |
| // Figure out the most restrictive integrity level transition (it should |
| // be the last one in the transition tree). |
| Handle<Map> previous = |
| handle(Map::cast(old_map_->GetBackPointer()), isolate_); |
| Symbol integrity_level_symbol; |
| TransitionsAccessor last_transitions(isolate_, previous); |
| if (!last_transitions.HasIntegrityLevelTransitionTo( |
| *old_map_, &integrity_level_symbol, &integrity_level_)) { |
| // The last transition was not integrity level transition - just bail out. |
| // This can happen in the following cases: |
| // - there are private symbol transitions following the integrity level |
| // transitions (see crbug.com/v8/8854). |
| // - there is a getter added in addition to an existing setter (or a setter |
| // in addition to an existing getter). |
| return false; |
| } |
| integrity_level_symbol_ = handle(integrity_level_symbol, isolate_); |
| integrity_source_map_ = previous; |
| |
| // Now walk up the back pointer chain and skip all integrity level |
| // transitions. If we encounter any non-integrity level transition interleaved |
| // with integrity level transitions, just bail out. |
| while (!integrity_source_map_->is_extensible()) { |
| previous = |
| handle(Map::cast(integrity_source_map_->GetBackPointer()), isolate_); |
| TransitionsAccessor transitions(isolate_, previous); |
| if (!transitions.HasIntegrityLevelTransitionTo(*integrity_source_map_)) { |
| return false; |
| } |
| integrity_source_map_ = previous; |
| } |
| |
| // Integrity-level transitions never change number of descriptors. |
| CHECK_EQ(old_map_->NumberOfOwnDescriptors(), |
| integrity_source_map_->NumberOfOwnDescriptors()); |
| |
| has_integrity_level_transition_ = true; |
| old_descriptors_ = |
| handle(integrity_source_map_->instance_descriptors(), isolate_); |
| return true; |
| } |
| |
| MapUpdater::State MapUpdater::FindRootMap() { |
| DCHECK_EQ(kInitialized, state_); |
| // Check the state of the root map. |
| root_map_ = handle(old_map_->FindRootMap(isolate_), isolate_); |
| ElementsKind from_kind = root_map_->elements_kind(); |
| ElementsKind to_kind = new_elements_kind_; |
| |
| if (root_map_->is_deprecated()) { |
| state_ = kEnd; |
| result_map_ = handle( |
| JSFunction::cast(root_map_->GetConstructor()).initial_map(), isolate_); |
| result_map_ = Map::AsElementsKind(isolate_, result_map_, to_kind); |
| DCHECK(result_map_->is_dictionary_map()); |
| return state_; |
| } |
| |
| if (!old_map_->EquivalentToForTransition(*root_map_)) { |
| return Normalize("Normalize_NotEquivalent"); |
| } else if (old_map_->is_extensible() != root_map_->is_extensible()) { |
| DCHECK(!old_map_->is_extensible()); |
| DCHECK(root_map_->is_extensible()); |
| // We have an integrity level transition in the tree, let us make a note |
| // of that transition to be able to replay it later. |
| if (!TrySaveIntegrityLevelTransitions()) { |
| return Normalize("Normalize_PrivateSymbolsOnNonExtensible"); |
| } |
| |
| // We want to build transitions to the original element kind (before |
| // the seal transitions), so change {to_kind} accordingly. |
| DCHECK(to_kind == DICTIONARY_ELEMENTS || |
| to_kind == SLOW_STRING_WRAPPER_ELEMENTS || |
| IsTypedArrayElementsKind(to_kind) || |
| IsAnyNonextensibleElementsKind(to_kind)); |
| to_kind = integrity_source_map_->elements_kind(); |
| } |
| |
| // TODO(ishell): Add a test for SLOW_SLOPPY_ARGUMENTS_ELEMENTS. |
| if (from_kind != to_kind && to_kind != DICTIONARY_ELEMENTS && |
| to_kind != SLOW_STRING_WRAPPER_ELEMENTS && |
| to_kind != SLOW_SLOPPY_ARGUMENTS_ELEMENTS && |
| !(IsTransitionableFastElementsKind(from_kind) && |
| IsMoreGeneralElementsKindTransition(from_kind, to_kind))) { |
| return Normalize("Normalize_InvalidElementsTransition"); |
| } |
| |
| int root_nof = root_map_->NumberOfOwnDescriptors(); |
| if (modified_descriptor_.is_found() && |
| modified_descriptor_.as_int() < root_nof) { |
| PropertyDetails old_details = |
| old_descriptors_->GetDetails(modified_descriptor_); |
| if (old_details.kind() != new_kind_ || |
| old_details.attributes() != new_attributes_) { |
| return Normalize("Normalize_RootModification1"); |
| } |
| if (old_details.location() != kField) { |
| return Normalize("Normalize_RootModification2"); |
| } |
| if (!new_representation_.fits_into(old_details.representation())) { |
| return Normalize("Normalize_RootModification4"); |
| } |
| |
| DCHECK_EQ(kData, old_details.kind()); |
| DCHECK_EQ(kData, new_kind_); |
| DCHECK_EQ(kField, new_location_); |
| |
| // Modify root map in-place. The GeneralizeField method is a no-op |
| // if the {old_map_} is already general enough to hold the requested |
| // {new_constness_} and {new_field_type_}. |
| GeneralizeField(old_map_, modified_descriptor_, new_constness_, |
| old_details.representation(), new_field_type_); |
| } |
| |
| // From here on, use the map with correct elements kind as root map. |
| root_map_ = Map::AsElementsKind(isolate_, root_map_, to_kind); |
| state_ = kAtRootMap; |
| return state_; // Not done yet. |
| } |
| |
| MapUpdater::State MapUpdater::FindTargetMap() { |
| DCHECK_EQ(kAtRootMap, state_); |
| target_map_ = root_map_; |
| |
| int root_nof = root_map_->NumberOfOwnDescriptors(); |
| for (InternalIndex i : InternalIndex::Range(root_nof, old_nof_)) { |
| PropertyDetails old_details = GetDetails(i); |
| Map transition = TransitionsAccessor(isolate_, target_map_) |
| .SearchTransition(GetKey(i), old_details.kind(), |
| old_details.attributes()); |
| if (transition.is_null()) break; |
| Handle<Map> tmp_map(transition, isolate_); |
| |
| Handle<DescriptorArray> tmp_descriptors(tmp_map->instance_descriptors(), |
| isolate_); |
| |
| // Check if target map is incompatible. |
| PropertyDetails tmp_details = tmp_descriptors->GetDetails(i); |
| DCHECK_EQ(old_details.kind(), tmp_details.kind()); |
| DCHECK_EQ(old_details.attributes(), tmp_details.attributes()); |
| if (old_details.kind() == kAccessor && |
| !EqualImmutableValues(GetValue(i), |
| tmp_descriptors->GetStrongValue(i))) { |
| // TODO(ishell): mutable accessors are not implemented yet. |
| return Normalize("Normalize_Incompatible"); |
| } |
| if (!IsGeneralizableTo(old_details.location(), tmp_details.location())) { |
| break; |
| } |
| Representation tmp_representation = tmp_details.representation(); |
| if (!old_details.representation().fits_into(tmp_representation)) { |
| // Try updating the field in-place to a generalized type. |
| Representation generalized = |
| tmp_representation.generalize(old_details.representation()); |
| if (!tmp_representation.CanBeInPlaceChangedTo(generalized)) { |
| break; |
| } |
| Handle<Map> field_owner(tmp_map->FindFieldOwner(isolate_, i), isolate_); |
| tmp_representation = generalized; |
| GeneralizeField(field_owner, i, tmp_details.constness(), |
| tmp_representation, |
| handle(tmp_descriptors->GetFieldType(i), isolate_)); |
| } |
| |
| if (tmp_details.location() == kField) { |
| Handle<FieldType> old_field_type = |
| GetOrComputeFieldType(i, old_details.location(), tmp_representation); |
| GeneralizeField(tmp_map, i, old_details.constness(), tmp_representation, |
| old_field_type); |
| } else { |
| // kDescriptor: Check that the value matches. |
| if (!EqualImmutableValues(GetValue(i), |
| tmp_descriptors->GetStrongValue(i))) { |
| break; |
| } |
| } |
| DCHECK(!tmp_map->is_deprecated()); |
| target_map_ = tmp_map; |
| } |
| |
| // Directly change the map if the target map is more general. |
| int target_nof = target_map_->NumberOfOwnDescriptors(); |
| if (target_nof == old_nof_) { |
| #ifdef DEBUG |
| if (modified_descriptor_.is_found()) { |
| DescriptorArray target_descriptors = target_map_->instance_descriptors(); |
| PropertyDetails details = |
| target_descriptors.GetDetails(modified_descriptor_); |
| DCHECK_EQ(new_kind_, details.kind()); |
| DCHECK_EQ(GetDetails(modified_descriptor_).attributes(), |
| details.attributes()); |
| DCHECK(IsGeneralizableTo(new_constness_, details.constness())); |
| DCHECK_EQ(new_location_, details.location()); |
| DCHECK(new_representation_.fits_into(details.representation())); |
| if (new_location_ == kField) { |
| DCHECK_EQ(kField, details.location()); |
| DCHECK(new_field_type_->NowIs( |
| target_descriptors.GetFieldType(modified_descriptor_))); |
| } else { |
| DCHECK(details.location() == kField || |
| EqualImmutableValues( |
| *new_value_, |
| target_descriptors.GetStrongValue(modified_descriptor_))); |
| } |
| } |
| #endif |
| if (*target_map_ != *old_map_) { |
| old_map_->NotifyLeafMapLayoutChange(isolate_); |
| } |
| if (!has_integrity_level_transition_) { |
| result_map_ = target_map_; |
| state_ = kEnd; |
| return state_; // Done. |
| } |
| |
| // We try to replay the integrity level transition here. |
| Map transition = TransitionsAccessor(isolate_, target_map_) |
| .SearchSpecial(*integrity_level_symbol_); |
| if (!transition.is_null()) { |
| result_map_ = handle(transition, isolate_); |
| state_ = kEnd; |
| return state_; // Done. |
| } |
| } |
| |
| // Find the last compatible target map in the transition tree. |
| for (InternalIndex i : InternalIndex::Range(target_nof, old_nof_)) { |
| PropertyDetails old_details = GetDetails(i); |
| Map transition = TransitionsAccessor(isolate_, target_map_) |
| .SearchTransition(GetKey(i), old_details.kind(), |
| old_details.attributes()); |
| if (transition.is_null()) break; |
| Handle<Map> tmp_map(transition, isolate_); |
| Handle<DescriptorArray> tmp_descriptors(tmp_map->instance_descriptors(), |
| isolate_); |
| #ifdef DEBUG |
| // Check that target map is compatible. |
| PropertyDetails tmp_details = tmp_descriptors->GetDetails(i); |
| DCHECK_EQ(old_details.kind(), tmp_details.kind()); |
| DCHECK_EQ(old_details.attributes(), tmp_details.attributes()); |
| #endif |
| if (old_details.kind() == kAccessor && |
| !EqualImmutableValues(GetValue(i), |
| tmp_descriptors->GetStrongValue(i))) { |
| return Normalize("Normalize_Incompatible"); |
| } |
| DCHECK(!tmp_map->is_deprecated()); |
| target_map_ = tmp_map; |
| } |
| |
| state_ = kAtTargetMap; |
| return state_; // Not done yet. |
| } |
| |
| Handle<DescriptorArray> MapUpdater::BuildDescriptorArray() { |
| InstanceType instance_type = old_map_->instance_type(); |
| int target_nof = target_map_->NumberOfOwnDescriptors(); |
| Handle<DescriptorArray> target_descriptors( |
| target_map_->instance_descriptors(), isolate_); |
| |
| // Allocate a new descriptor array large enough to hold the required |
| // descriptors, with minimally the exact same size as the old descriptor |
| // array. |
| int new_slack = |
| std::max<int>(old_nof_, old_descriptors_->number_of_descriptors()) - |
| old_nof_; |
| Handle<DescriptorArray> new_descriptors = |
| DescriptorArray::Allocate(isolate_, old_nof_, new_slack); |
| DCHECK(new_descriptors->number_of_all_descriptors() > |
| target_descriptors->number_of_all_descriptors() || |
| new_descriptors->number_of_slack_descriptors() > 0 || |
| new_descriptors->number_of_descriptors() == |
| old_descriptors_->number_of_descriptors()); |
| DCHECK(new_descriptors->number_of_descriptors() == old_nof_); |
| |
| int root_nof = root_map_->NumberOfOwnDescriptors(); |
| |
| // Given that we passed root modification check in FindRootMap() so |
| // the root descriptors are either not modified at all or already more |
| // general than we requested. Take |root_nof| entries as is. |
| // 0 -> |root_nof| |
| int current_offset = 0; |
| for (InternalIndex i : InternalIndex::Range(root_nof)) { |
| PropertyDetails old_details = old_descriptors_->GetDetails(i); |
| if (old_details.location() == kField) { |
| current_offset += old_details.field_width_in_words(); |
| } |
| Descriptor d(handle(GetKey(i), isolate_), |
| MaybeObjectHandle(old_descriptors_->GetValue(i), isolate_), |
| old_details); |
| new_descriptors->Set(i, &d); |
| } |
| |
| // Merge "updated" old_descriptor entries with target_descriptor entries. |
| // |root_nof| -> |target_nof| |
| for (InternalIndex i : InternalIndex::Range(root_nof, target_nof)) { |
| Handle<Name> key(GetKey(i), isolate_); |
| PropertyDetails old_details = GetDetails(i); |
| PropertyDetails target_details = target_descriptors->GetDetails(i); |
| |
| PropertyKind next_kind = old_details.kind(); |
| PropertyAttributes next_attributes = old_details.attributes(); |
| DCHECK_EQ(next_kind, target_details.kind()); |
| DCHECK_EQ(next_attributes, target_details.attributes()); |
| |
| PropertyConstness next_constness = GeneralizeConstness( |
| old_details.constness(), target_details.constness()); |
| |
| // Note: failed values equality check does not invalidate per-object |
| // property constness. |
| PropertyLocation next_location = |
| old_details.location() == kField || |
| target_details.location() == kField || |
| !EqualImmutableValues(target_descriptors->GetStrongValue(i), |
| GetValue(i)) |
| ? kField |
| : kDescriptor; |
| |
| // Ensure that mutable values are stored in fields. |
| DCHECK_IMPLIES(next_constness == PropertyConstness::kMutable, |
| next_location == kField); |
| |
| Representation next_representation = |
| old_details.representation().generalize( |
| target_details.representation()); |
| |
| if (next_location == kField) { |
| Handle<FieldType> old_field_type = |
| GetOrComputeFieldType(i, old_details.location(), next_representation); |
| |
| Handle<FieldType> target_field_type = |
| GetOrComputeFieldType(target_descriptors, i, |
| target_details.location(), next_representation); |
| |
| Handle<FieldType> next_field_type = Map::GeneralizeFieldType( |
| old_details.representation(), old_field_type, next_representation, |
| target_field_type, isolate_); |
| |
| Map::GeneralizeIfCanHaveTransitionableFastElementsKind( |
| isolate_, instance_type, &next_representation, &next_field_type); |
| |
| MaybeObjectHandle wrapped_type( |
| Map::WrapFieldType(isolate_, next_field_type)); |
| Descriptor d; |
| if (next_kind == kData) { |
| d = Descriptor::DataField(key, current_offset, next_attributes, |
| next_constness, next_representation, |
| wrapped_type); |
| } else { |
| // TODO(ishell): mutable accessors are not implemented yet. |
| UNIMPLEMENTED(); |
| } |
| current_offset += d.GetDetails().field_width_in_words(); |
| new_descriptors->Set(i, &d); |
| } else { |
| DCHECK_EQ(kDescriptor, next_location); |
| DCHECK_EQ(PropertyConstness::kConst, next_constness); |
| |
| Handle<Object> value(GetValue(i), isolate_); |
| DCHECK_EQ(kAccessor, next_kind); |
| Descriptor d = Descriptor::AccessorConstant(key, value, next_attributes); |
| new_descriptors->Set(i, &d); |
| } |
| } |
| |
| // Take "updated" old_descriptor entries. |
| // |target_nof| -> |old_nof| |
| for (InternalIndex i : InternalIndex::Range(target_nof, old_nof_)) { |
| PropertyDetails old_details = GetDetails(i); |
| Handle<Name> key(GetKey(i), isolate_); |
| |
| PropertyKind next_kind = old_details.kind(); |
| PropertyAttributes next_attributes = old_details.attributes(); |
| PropertyConstness next_constness = old_details.constness(); |
| PropertyLocation next_location = old_details.location(); |
| Representation next_representation = old_details.representation(); |
| |
| Descriptor d; |
| if (next_location == kField) { |
| Handle<FieldType> next_field_type = |
| GetOrComputeFieldType(i, old_details.location(), next_representation); |
| |
| // If the |new_elements_kind_| is still transitionable then the old map's |
| // elements kind is also transitionable and therefore the old descriptors |
| // array must already have generalized field type. |
| CHECK_IMPLIES( |
| is_transitionable_fast_elements_kind_, |
| Map::IsMostGeneralFieldType(next_representation, *next_field_type)); |
| |
| MaybeObjectHandle wrapped_type( |
| Map::WrapFieldType(isolate_, next_field_type)); |
| Descriptor d; |
| if (next_kind == kData) { |
| d = Descriptor::DataField(key, current_offset, next_attributes, |
| next_constness, next_representation, |
| wrapped_type); |
| } else { |
| // TODO(ishell): mutable accessors are not implemented yet. |
| UNIMPLEMENTED(); |
| } |
| current_offset += d.GetDetails().field_width_in_words(); |
| new_descriptors->Set(i, &d); |
| } else { |
| DCHECK_EQ(kDescriptor, next_location); |
| DCHECK_EQ(PropertyConstness::kConst, next_constness); |
| |
| Handle<Object> value(GetValue(i), isolate_); |
| if (next_kind == kData) { |
| d = Descriptor::DataConstant(key, value, next_attributes); |
| } else { |
| DCHECK_EQ(kAccessor, next_kind); |
| d = Descriptor::AccessorConstant(key, value, next_attributes); |
| } |
| new_descriptors->Set(i, &d); |
| } |
| } |
| |
| new_descriptors->Sort(); |
| return new_descriptors; |
| } |
| |
| Handle<Map> MapUpdater::FindSplitMap(Handle<DescriptorArray> descriptors) { |
| DisallowHeapAllocation no_allocation; |
| |
| int root_nof = root_map_->NumberOfOwnDescriptors(); |
| Map current = *root_map_; |
| for (InternalIndex i : InternalIndex::Range(root_nof, old_nof_)) { |
| Name name = descriptors->GetKey(i); |
| PropertyDetails details = descriptors->GetDetails(i); |
| Map next = |
| TransitionsAccessor(isolate_, current, &no_allocation) |
| .SearchTransition(name, details.kind(), details.attributes()); |
| if (next.is_null()) break; |
| DescriptorArray next_descriptors = next.instance_descriptors(); |
| |
| PropertyDetails next_details = next_descriptors.GetDetails(i); |
| DCHECK_EQ(details.kind(), next_details.kind()); |
| DCHECK_EQ(details.attributes(), next_details.attributes()); |
| if (details.constness() != next_details.constness()) break; |
| if (details.location() != next_details.location()) break; |
| if (!details.representation().Equals(next_details.representation())) break; |
| |
| if (next_details.location() == kField) { |
| FieldType next_field_type = next_descriptors.GetFieldType(i); |
| if (!descriptors->GetFieldType(i).NowIs(next_field_type)) { |
| break; |
| } |
| } else { |
| if (!EqualImmutableValues(descriptors->GetStrongValue(i), |
| next_descriptors.GetStrongValue(i))) { |
| break; |
| } |
| } |
| current = next; |
| } |
| return handle(current, isolate_); |
| } |
| |
| MapUpdater::State MapUpdater::ConstructNewMap() { |
| Handle<DescriptorArray> new_descriptors = BuildDescriptorArray(); |
| |
| Handle<Map> split_map = FindSplitMap(new_descriptors); |
| int split_nof = split_map->NumberOfOwnDescriptors(); |
| if (old_nof_ == split_nof) { |
| CHECK(has_integrity_level_transition_); |
| state_ = kAtIntegrityLevelSource; |
| return state_; |
| } |
| InternalIndex split_index(split_nof); |
| PropertyDetails split_details = GetDetails(split_index); |
| TransitionsAccessor transitions(isolate_, split_map); |
| |
| // Invalidate a transition target at |key|. |
| Handle<Map> maybe_transition( |
| transitions.SearchTransition(GetKey(split_index), split_details.kind(), |
| split_details.attributes()), |
| isolate_); |
| if (!maybe_transition->is_null()) { |
| maybe_transition->DeprecateTransitionTree(isolate_); |
| } |
| |
| // If |maybe_transition| is not nullptr then the transition array already |
| // contains entry for given descriptor. This means that the transition |
| // could be inserted regardless of whether transitions array is full or not. |
| if (maybe_transition->is_null() && !transitions.CanHaveMoreTransitions()) { |
| return Normalize("Normalize_CantHaveMoreTransitions"); |
| } |
| |
| old_map_->NotifyLeafMapLayoutChange(isolate_); |
| |
| if (FLAG_trace_generalization && modified_descriptor_.is_found()) { |
| PropertyDetails old_details = |
| old_descriptors_->GetDetails(modified_descriptor_); |
| PropertyDetails new_details = |
| new_descriptors->GetDetails(modified_descriptor_); |
| MaybeHandle<FieldType> old_field_type; |
| MaybeHandle<FieldType> new_field_type; |
| MaybeHandle<Object> old_value; |
| MaybeHandle<Object> new_value; |
| if (old_details.location() == kField) { |
| old_field_type = handle( |
| old_descriptors_->GetFieldType(modified_descriptor_), isolate_); |
| } else { |
| old_value = handle(old_descriptors_->GetStrongValue(modified_descriptor_), |
| isolate_); |
| } |
| if (new_details.location() == kField) { |
| new_field_type = |
| handle(new_descriptors->GetFieldType(modified_descriptor_), isolate_); |
| } else { |
| new_value = handle(new_descriptors->GetStrongValue(modified_descriptor_), |
| isolate_); |
| } |
| |
| old_map_->PrintGeneralization( |
| isolate_, stdout, "", modified_descriptor_, split_nof, old_nof_, |
| old_details.location() == kDescriptor && new_location_ == kField, |
| old_details.representation(), new_details.representation(), |
| old_details.constness(), new_details.constness(), old_field_type, |
| old_value, new_field_type, new_value); |
| } |
| |
| Handle<LayoutDescriptor> new_layout_descriptor = |
| LayoutDescriptor::New(isolate_, split_map, new_descriptors, old_nof_); |
| |
| Handle<Map> new_map = Map::AddMissingTransitions( |
| isolate_, split_map, new_descriptors, new_layout_descriptor); |
| |
| // Deprecated part of the transition tree is no longer reachable, so replace |
| // current instance descriptors in the "survived" part of the tree with |
| // the new descriptors to maintain descriptors sharing invariant. |
| split_map->ReplaceDescriptors(isolate_, *new_descriptors, |
| *new_layout_descriptor); |
| |
| if (has_integrity_level_transition_) { |
| target_map_ = new_map; |
| state_ = kAtIntegrityLevelSource; |
| } else { |
| result_map_ = new_map; |
| state_ = kEnd; |
| } |
| return state_; // Done. |
| } |
| |
| MapUpdater::State MapUpdater::ConstructNewMapWithIntegrityLevelTransition() { |
| DCHECK_EQ(kAtIntegrityLevelSource, state_); |
| |
| TransitionsAccessor transitions(isolate_, target_map_); |
| if (!transitions.CanHaveMoreTransitions()) { |
| return Normalize("Normalize_CantHaveMoreTransitions"); |
| } |
| |
| result_map_ = Map::CopyForPreventExtensions( |
| isolate_, target_map_, integrity_level_, integrity_level_symbol_, |
| "CopyForPreventExtensions", |
| old_map_->elements_kind() == DICTIONARY_ELEMENTS); |
| DCHECK_IMPLIES(old_map_->elements_kind() == DICTIONARY_ELEMENTS, |
| result_map_->elements_kind() == DICTIONARY_ELEMENTS); |
| |
| state_ = kEnd; |
| return state_; |
| } |
| |
| } // namespace internal |
| } // namespace v8 |
