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|
// Copyright 2015 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 <ostream>
#include "src/compiler/access-info.h"
#include "src/builtins/accessors.h"
#include "src/compiler/compilation-dependencies.h"
#include "src/compiler/compilation-dependency.h"
#include "src/compiler/simplified-operator.h"
#include "src/compiler/type-cache.h"
#include "src/ic/call-optimization.h"
#include "src/logging/counters.h"
#include "src/objects/cell-inl.h"
#include "src/objects/field-index-inl.h"
#include "src/objects/field-type.h"
#include "src/objects/module-inl.h"
#include "src/objects/objects-inl.h"
#include "src/objects/struct-inl.h"
#include "src/objects/templates.h"
namespace v8 {
namespace internal {
namespace compiler {
namespace {
bool CanInlinePropertyAccess(Handle<Map> map) {
// We can inline property access to prototypes of all primitives, except
// the special Oddball ones that have no wrapper counterparts (i.e. Null,
// Undefined and TheHole).
STATIC_ASSERT(ODDBALL_TYPE == LAST_PRIMITIVE_HEAP_OBJECT_TYPE);
if (map->IsBooleanMap()) return true;
if (map->instance_type() < LAST_PRIMITIVE_HEAP_OBJECT_TYPE) return true;
return map->IsJSObjectMap() && !map->is_dictionary_map() &&
!map->has_named_interceptor() &&
// TODO(verwaest): Whitelist contexts to which we have access.
!map->is_access_check_needed();
}
} // namespace
std::ostream& operator<<(std::ostream& os, AccessMode access_mode) {
switch (access_mode) {
case AccessMode::kLoad:
return os << "Load";
case AccessMode::kStore:
return os << "Store";
case AccessMode::kStoreInLiteral:
return os << "StoreInLiteral";
case AccessMode::kHas:
return os << "Has";
}
UNREACHABLE();
}
ElementAccessInfo::ElementAccessInfo(ZoneVector<Handle<Map>>&& receiver_maps,
ElementsKind elements_kind, Zone* zone)
: elements_kind_(elements_kind),
receiver_maps_(receiver_maps),
transition_sources_(zone) {
CHECK(!receiver_maps.empty());
}
// static
PropertyAccessInfo PropertyAccessInfo::Invalid(Zone* zone) {
return PropertyAccessInfo(zone);
}
// static
PropertyAccessInfo PropertyAccessInfo::NotFound(Zone* zone,
Handle<Map> receiver_map,
MaybeHandle<JSObject> holder) {
return PropertyAccessInfo(zone, kNotFound, holder, {{receiver_map}, zone});
}
// static
PropertyAccessInfo PropertyAccessInfo::DataField(
Zone* zone, Handle<Map> receiver_map,
ZoneVector<CompilationDependency const*>&& dependencies,
FieldIndex field_index, Representation field_representation,
Type field_type, Handle<Map> field_owner_map, MaybeHandle<Map> field_map,
MaybeHandle<JSObject> holder, MaybeHandle<Map> transition_map) {
return PropertyAccessInfo(kDataField, holder, transition_map, field_index,
field_representation, field_type, field_owner_map,
field_map, {{receiver_map}, zone},
std::move(dependencies));
}
// static
PropertyAccessInfo PropertyAccessInfo::DataConstant(
Zone* zone, Handle<Map> receiver_map,
ZoneVector<CompilationDependency const*>&& dependencies,
FieldIndex field_index, Representation field_representation,
Type field_type, Handle<Map> field_owner_map, MaybeHandle<Map> field_map,
MaybeHandle<JSObject> holder, MaybeHandle<Map> transition_map) {
return PropertyAccessInfo(kDataConstant, holder, transition_map, field_index,
field_representation, field_type, field_owner_map,
field_map, {{receiver_map}, zone},
std::move(dependencies));
}
// static
PropertyAccessInfo PropertyAccessInfo::AccessorConstant(
Zone* zone, Handle<Map> receiver_map, Handle<Object> constant,
MaybeHandle<JSObject> holder) {
return PropertyAccessInfo(zone, kAccessorConstant, holder, constant,
{{receiver_map}, zone});
}
// static
PropertyAccessInfo PropertyAccessInfo::ModuleExport(Zone* zone,
Handle<Map> receiver_map,
Handle<Cell> cell) {
return PropertyAccessInfo(zone, kModuleExport, MaybeHandle<JSObject>(), cell,
{{receiver_map}, zone});
}
// static
PropertyAccessInfo PropertyAccessInfo::StringLength(Zone* zone,
Handle<Map> receiver_map) {
return PropertyAccessInfo(zone, kStringLength, MaybeHandle<JSObject>(),
{{receiver_map}, zone});
}
PropertyAccessInfo::PropertyAccessInfo(Zone* zone)
: kind_(kInvalid),
receiver_maps_(zone),
unrecorded_dependencies_(zone),
field_representation_(Representation::None()),
field_type_(Type::None()) {}
PropertyAccessInfo::PropertyAccessInfo(Zone* zone, Kind kind,
MaybeHandle<JSObject> holder,
ZoneVector<Handle<Map>>&& receiver_maps)
: kind_(kind),
receiver_maps_(receiver_maps),
unrecorded_dependencies_(zone),
holder_(holder),
field_representation_(Representation::None()),
field_type_(Type::None()) {}
PropertyAccessInfo::PropertyAccessInfo(Zone* zone, Kind kind,
MaybeHandle<JSObject> holder,
Handle<Object> constant,
ZoneVector<Handle<Map>>&& receiver_maps)
: kind_(kind),
receiver_maps_(receiver_maps),
unrecorded_dependencies_(zone),
constant_(constant),
holder_(holder),
field_representation_(Representation::None()),
field_type_(Type::Any()) {}
PropertyAccessInfo::PropertyAccessInfo(
Kind kind, MaybeHandle<JSObject> holder, MaybeHandle<Map> transition_map,
FieldIndex field_index, Representation field_representation,
Type field_type, Handle<Map> field_owner_map, MaybeHandle<Map> field_map,
ZoneVector<Handle<Map>>&& receiver_maps,
ZoneVector<CompilationDependency const*>&& unrecorded_dependencies)
: kind_(kind),
receiver_maps_(receiver_maps),
unrecorded_dependencies_(std::move(unrecorded_dependencies)),
transition_map_(transition_map),
holder_(holder),
field_index_(field_index),
field_representation_(field_representation),
field_type_(field_type),
field_owner_map_(field_owner_map),
field_map_(field_map) {
DCHECK_IMPLIES(!transition_map.is_null(),
field_owner_map.address() == transition_map.address());
}
bool PropertyAccessInfo::Merge(PropertyAccessInfo const* that,
AccessMode access_mode, Zone* zone) {
if (this->kind_ != that->kind_) return false;
if (this->holder_.address() != that->holder_.address()) return false;
switch (this->kind_) {
case kInvalid:
return that->kind_ == kInvalid;
case kDataField:
case kDataConstant: {
// Check if we actually access the same field (we use the
// GetFieldAccessStubKey method here just like the ICs do
// since that way we only compare the relevant bits of the
// field indices).
if (this->field_index_.GetFieldAccessStubKey() ==
that->field_index_.GetFieldAccessStubKey()) {
switch (access_mode) {
case AccessMode::kHas:
case AccessMode::kLoad: {
if (!this->field_representation_.Equals(
that->field_representation_)) {
if (this->field_representation_.IsDouble() ||
that->field_representation_.IsDouble()) {
return false;
}
this->field_representation_ = Representation::Tagged();
}
if (this->field_map_.address() != that->field_map_.address()) {
this->field_map_ = MaybeHandle<Map>();
}
break;
}
case AccessMode::kStore:
case AccessMode::kStoreInLiteral: {
// For stores, the field map and field representation information
// must match exactly, otherwise we cannot merge the stores. We
// also need to make sure that in case of transitioning stores,
// the transition targets match.
if (this->field_map_.address() != that->field_map_.address() ||
!this->field_representation_.Equals(
that->field_representation_) ||
this->transition_map_.address() !=
that->transition_map_.address()) {
return false;
}
break;
}
}
this->field_type_ =
Type::Union(this->field_type_, that->field_type_, zone);
this->receiver_maps_.insert(this->receiver_maps_.end(),
that->receiver_maps_.begin(),
that->receiver_maps_.end());
this->unrecorded_dependencies_.insert(
this->unrecorded_dependencies_.end(),
that->unrecorded_dependencies_.begin(),
that->unrecorded_dependencies_.end());
return true;
}
return false;
}
case kAccessorConstant: {
// Check if we actually access the same constant.
if (this->constant_.address() == that->constant_.address()) {
DCHECK(this->unrecorded_dependencies_.empty());
DCHECK(that->unrecorded_dependencies_.empty());
this->receiver_maps_.insert(this->receiver_maps_.end(),
that->receiver_maps_.begin(),
that->receiver_maps_.end());
return true;
}
return false;
}
case kNotFound:
case kStringLength: {
DCHECK(this->unrecorded_dependencies_.empty());
DCHECK(that->unrecorded_dependencies_.empty());
this->receiver_maps_.insert(this->receiver_maps_.end(),
that->receiver_maps_.begin(),
that->receiver_maps_.end());
return true;
}
case kModuleExport:
return false;
}
}
ConstFieldInfo PropertyAccessInfo::GetConstFieldInfo() const {
if (IsDataConstant()) {
return ConstFieldInfo(field_owner_map_.ToHandleChecked());
}
return ConstFieldInfo::None();
}
AccessInfoFactory::AccessInfoFactory(JSHeapBroker* broker,
CompilationDependencies* dependencies,
Zone* zone)
: broker_(broker),
dependencies_(dependencies),
type_cache_(TypeCache::Get()),
zone_(zone) {}
base::Optional<ElementAccessInfo> AccessInfoFactory::ComputeElementAccessInfo(
Handle<Map> map, AccessMode access_mode) const {
// Check if it is safe to inline element access for the {map}.
MapRef map_ref(broker(), map);
if (!CanInlineElementAccess(map_ref)) return base::nullopt;
ElementsKind const elements_kind = map_ref.elements_kind();
return ElementAccessInfo({{map}, zone()}, elements_kind, zone());
}
bool AccessInfoFactory::ComputeElementAccessInfos(
ElementAccessFeedback const& feedback,
ZoneVector<ElementAccessInfo>* access_infos) const {
AccessMode access_mode = feedback.keyed_mode().access_mode();
if (access_mode == AccessMode::kLoad || access_mode == AccessMode::kHas) {
// For polymorphic loads of similar elements kinds (i.e. all tagged or all
// double), always use the "worst case" code without a transition. This is
// much faster than transitioning the elements to the worst case, trading a
// TransitionElementsKind for a CheckMaps, avoiding mutation of the array.
base::Optional<ElementAccessInfo> access_info =
ConsolidateElementLoad(feedback);
if (access_info.has_value()) {
access_infos->push_back(*access_info);
return true;
}
}
for (auto const& group : feedback.transition_groups()) {
DCHECK(!group.empty());
Handle<Map> target = group.front();
base::Optional<ElementAccessInfo> access_info =
ComputeElementAccessInfo(target, access_mode);
if (!access_info.has_value()) return false;
for (size_t i = 1; i < group.size(); ++i) {
access_info->AddTransitionSource(group[i]);
}
access_infos->push_back(*access_info);
}
return true;
}
PropertyAccessInfo AccessInfoFactory::ComputeDataFieldAccessInfo(
Handle<Map> receiver_map, Handle<Map> map, MaybeHandle<JSObject> holder,
InternalIndex descriptor, AccessMode access_mode) const {
DCHECK(descriptor.is_found());
Handle<DescriptorArray> descriptors(map->instance_descriptors(), isolate());
PropertyDetails const details = descriptors->GetDetails(descriptor);
int index = descriptors->GetFieldIndex(descriptor);
Representation details_representation = details.representation();
if (details_representation.IsNone()) {
// The ICs collect feedback in PREMONOMORPHIC state already,
// but at this point the {receiver_map} might still contain
// fields for which the representation has not yet been
// determined by the runtime. So we need to catch this case
// here and fall back to use the regular IC logic instead.
return PropertyAccessInfo::Invalid(zone());
}
FieldIndex field_index =
FieldIndex::ForPropertyIndex(*map, index, details_representation);
Type field_type = Type::NonInternal();
MaybeHandle<Map> field_map;
MapRef map_ref(broker(), map);
ZoneVector<CompilationDependency const*> unrecorded_dependencies(zone());
map_ref.SerializeOwnDescriptor(descriptor);
if (details_representation.IsSmi()) {
field_type = Type::SignedSmall();
unrecorded_dependencies.push_back(
dependencies()->FieldRepresentationDependencyOffTheRecord(map_ref,
descriptor));
} else if (details_representation.IsDouble()) {
field_type = type_cache_->kFloat64;
if (!FLAG_unbox_double_fields) {
unrecorded_dependencies.push_back(
dependencies()->FieldRepresentationDependencyOffTheRecord(
map_ref, descriptor));
}
} else if (details_representation.IsHeapObject()) {
// Extract the field type from the property details (make sure its
// representation is TaggedPointer to reflect the heap object case).
Handle<FieldType> descriptors_field_type(
descriptors->GetFieldType(descriptor), isolate());
if (descriptors_field_type->IsNone()) {
// Store is not safe if the field type was cleared.
if (access_mode == AccessMode::kStore) {
return PropertyAccessInfo::Invalid(zone());
}
// The field type was cleared by the GC, so we don't know anything
// about the contents now.
}
unrecorded_dependencies.push_back(
dependencies()->FieldRepresentationDependencyOffTheRecord(map_ref,
descriptor));
if (descriptors_field_type->IsClass()) {
// Remember the field map, and try to infer a useful type.
Handle<Map> map(descriptors_field_type->AsClass(), isolate());
field_type = Type::For(MapRef(broker(), map));
field_map = MaybeHandle<Map>(map);
}
} else {
CHECK(details_representation.IsTagged());
}
// TODO(turbofan): We may want to do this only depending on the use
// of the access info.
unrecorded_dependencies.push_back(
dependencies()->FieldTypeDependencyOffTheRecord(map_ref, descriptor));
PropertyConstness constness;
if (details.IsReadOnly() && !details.IsConfigurable()) {
constness = PropertyConstness::kConst;
} else if (FLAG_turboprop && !map->is_prototype_map()) {
// The constness feedback is too unstable for the aggresive compilation
// of turboprop.
constness = PropertyConstness::kMutable;
} else {
map_ref.SerializeOwnDescriptor(descriptor);
constness = dependencies()->DependOnFieldConstness(map_ref, descriptor);
}
Handle<Map> field_owner_map(map->FindFieldOwner(isolate(), descriptor),
isolate());
switch (constness) {
case PropertyConstness::kMutable:
return PropertyAccessInfo::DataField(
zone(), receiver_map, std::move(unrecorded_dependencies), field_index,
details_representation, field_type, field_owner_map, field_map,
holder);
case PropertyConstness::kConst:
return PropertyAccessInfo::DataConstant(
zone(), receiver_map, std::move(unrecorded_dependencies), field_index,
details_representation, field_type, field_owner_map, field_map,
holder);
}
UNREACHABLE();
}
PropertyAccessInfo AccessInfoFactory::ComputeAccessorDescriptorAccessInfo(
Handle<Map> receiver_map, Handle<Name> name, Handle<Map> map,
MaybeHandle<JSObject> holder, InternalIndex descriptor,
AccessMode access_mode) const {
DCHECK(descriptor.is_found());
Handle<DescriptorArray> descriptors(map->instance_descriptors(), isolate());
SLOW_DCHECK(descriptor == descriptors->Search(*name, *map));
if (map->instance_type() == JS_MODULE_NAMESPACE_TYPE) {
DCHECK(map->is_prototype_map());
Handle<PrototypeInfo> proto_info(PrototypeInfo::cast(map->prototype_info()),
isolate());
Handle<JSModuleNamespace> module_namespace(
JSModuleNamespace::cast(proto_info->module_namespace()), isolate());
Handle<Cell> cell(
Cell::cast(module_namespace->module().exports().Lookup(
ReadOnlyRoots(isolate()), name, Smi::ToInt(name->GetHash()))),
isolate());
if (cell->value().IsTheHole(isolate())) {
// This module has not been fully initialized yet.
return PropertyAccessInfo::Invalid(zone());
}
return PropertyAccessInfo::ModuleExport(zone(), receiver_map, cell);
}
if (access_mode == AccessMode::kHas) {
// HasProperty checks don't call getter/setters, existence is sufficient.
return PropertyAccessInfo::AccessorConstant(zone(), receiver_map,
Handle<Object>(), holder);
}
Handle<Object> accessors(descriptors->GetStrongValue(descriptor), isolate());
if (!accessors->IsAccessorPair()) {
return PropertyAccessInfo::Invalid(zone());
}
Handle<Object> accessor(access_mode == AccessMode::kLoad
? Handle<AccessorPair>::cast(accessors)->getter()
: Handle<AccessorPair>::cast(accessors)->setter(),
isolate());
if (!accessor->IsJSFunction()) {
CallOptimization optimization(isolate(), accessor);
if (!optimization.is_simple_api_call() ||
optimization.IsCrossContextLazyAccessorPair(
*broker()->target_native_context().object(), *map)) {
return PropertyAccessInfo::Invalid(zone());
}
CallOptimization::HolderLookup lookup;
holder = optimization.LookupHolderOfExpectedType(receiver_map, &lookup);
if (lookup == CallOptimization::kHolderNotFound) {
return PropertyAccessInfo::Invalid(zone());
}
DCHECK_IMPLIES(lookup == CallOptimization::kHolderIsReceiver,
holder.is_null());
DCHECK_IMPLIES(lookup == CallOptimization::kHolderFound, !holder.is_null());
}
if (access_mode == AccessMode::kLoad) {
Handle<Name> cached_property_name;
if (FunctionTemplateInfo::TryGetCachedPropertyName(isolate(), accessor)
.ToHandle(&cached_property_name)) {
PropertyAccessInfo access_info =
ComputePropertyAccessInfo(map, cached_property_name, access_mode);
if (!access_info.IsInvalid()) return access_info;
}
}
return PropertyAccessInfo::AccessorConstant(zone(), receiver_map, accessor,
holder);
}
PropertyAccessInfo AccessInfoFactory::ComputePropertyAccessInfo(
Handle<Map> map, Handle<Name> name, AccessMode access_mode) const {
CHECK(name->IsUniqueName());
if (access_mode == AccessMode::kHas && !map->IsJSReceiverMap()) {
return PropertyAccessInfo::Invalid(zone());
}
// Check if it is safe to inline property access for the {map}.
if (!CanInlinePropertyAccess(map)) {
return PropertyAccessInfo::Invalid(zone());
}
// We support fast inline cases for certain JSObject getters.
if (access_mode == AccessMode::kLoad || access_mode == AccessMode::kHas) {
PropertyAccessInfo access_info = LookupSpecialFieldAccessor(map, name);
if (!access_info.IsInvalid()) return access_info;
}
// Remember the receiver map. We use {map} as loop variable.
Handle<Map> receiver_map = map;
MaybeHandle<JSObject> holder;
while (true) {
// Lookup the named property on the {map}.
Handle<DescriptorArray> descriptors(map->instance_descriptors(), isolate());
InternalIndex const number = descriptors->Search(*name, *map);
if (number.is_found()) {
PropertyDetails const details = descriptors->GetDetails(number);
if (access_mode == AccessMode::kStore ||
access_mode == AccessMode::kStoreInLiteral) {
// Don't bother optimizing stores to read-only properties.
if (details.IsReadOnly()) {
return PropertyAccessInfo::Invalid(zone());
}
if (details.kind() == kData && !holder.is_null()) {
// This is a store to a property not found on the receiver but on a
// prototype. According to ES6 section 9.1.9 [[Set]], we need to
// create a new data property on the receiver. We can still optimize
// if such a transition already exists.
return LookupTransition(receiver_map, name, holder);
}
}
if (details.location() == kField) {
if (details.kind() == kData) {
return ComputeDataFieldAccessInfo(receiver_map, map, holder, number,
access_mode);
} else {
DCHECK_EQ(kAccessor, details.kind());
// TODO(turbofan): Add support for general accessors?
return PropertyAccessInfo::Invalid(zone());
}
} else {
DCHECK_EQ(kDescriptor, details.location());
DCHECK_EQ(kAccessor, details.kind());
return ComputeAccessorDescriptorAccessInfo(receiver_map, name, map,
holder, number, access_mode);
}
UNREACHABLE();
}
// The property wasn't found on {map}. Look on the prototype if appropriate.
// Don't search on the prototype chain for special indices in case of
// integer indexed exotic objects (see ES6 section 9.4.5).
if (map->IsJSTypedArrayMap() && name->IsString() &&
IsSpecialIndex(String::cast(*name))) {
return PropertyAccessInfo::Invalid(zone());
}
// Don't search on the prototype when storing in literals.
if (access_mode == AccessMode::kStoreInLiteral) {
return LookupTransition(receiver_map, name, holder);
}
// Don't lookup private symbols on the prototype chain.
if (name->IsPrivate()) {
return PropertyAccessInfo::Invalid(zone());
}
// Walk up the prototype chain.
MapRef(broker(), map).SerializePrototype();
if (!map->prototype().IsJSObject()) {
// Perform the implicit ToObject for primitives here.
// Implemented according to ES6 section 7.3.2 GetV (V, P).
Handle<JSFunction> constructor;
if (Map::GetConstructorFunction(
map, broker()->target_native_context().object())
.ToHandle(&constructor)) {
map = handle(constructor->initial_map(), isolate());
DCHECK(map->prototype().IsJSObject());
} else if (map->prototype().IsNull(isolate())) {
// Store to property not found on the receiver or any prototype, we need
// to transition to a new data property.
// Implemented according to ES6 section 9.1.9 [[Set]] (P, V, Receiver)
if (access_mode == AccessMode::kStore) {
return LookupTransition(receiver_map, name, holder);
}
// The property was not found (access returns undefined or throws
// depending on the language mode of the load operation.
// Implemented according to ES6 section 9.1.8 [[Get]] (P, Receiver)
return PropertyAccessInfo::NotFound(zone(), receiver_map, holder);
} else {
return PropertyAccessInfo::Invalid(zone());
}
}
Handle<JSObject> map_prototype(JSObject::cast(map->prototype()), isolate());
CHECK(!map_prototype->map().is_deprecated());
map = handle(map_prototype->map(), isolate());
holder = map_prototype;
if (!CanInlinePropertyAccess(map)) {
return PropertyAccessInfo::Invalid(zone());
}
// Successful lookup on prototype chain needs to guarantee that all
// the prototypes up to the holder have stable maps. Let us make sure
// the prototype maps are stable here.
CHECK(map->is_stable());
}
UNREACHABLE();
}
PropertyAccessInfo AccessInfoFactory::FinalizePropertyAccessInfosAsOne(
ZoneVector<PropertyAccessInfo> access_infos, AccessMode access_mode) const {
ZoneVector<PropertyAccessInfo> merged_access_infos(zone());
MergePropertyAccessInfos(access_infos, access_mode, &merged_access_infos);
if (merged_access_infos.size() == 1) {
PropertyAccessInfo& result = merged_access_infos.front();
if (!result.IsInvalid()) {
result.RecordDependencies(dependencies());
return result;
}
}
return PropertyAccessInfo::Invalid(zone());
}
void AccessInfoFactory::ComputePropertyAccessInfos(
MapHandles const& maps, Handle<Name> name, AccessMode access_mode,
ZoneVector<PropertyAccessInfo>* access_infos) const {
DCHECK(access_infos->empty());
for (Handle<Map> map : maps) {
access_infos->push_back(ComputePropertyAccessInfo(map, name, access_mode));
}
}
void PropertyAccessInfo::RecordDependencies(
CompilationDependencies* dependencies) {
for (CompilationDependency const* d : unrecorded_dependencies_) {
dependencies->RecordDependency(d);
}
unrecorded_dependencies_.clear();
}
bool AccessInfoFactory::FinalizePropertyAccessInfos(
ZoneVector<PropertyAccessInfo> access_infos, AccessMode access_mode,
ZoneVector<PropertyAccessInfo>* result) const {
if (access_infos.empty()) return false;
MergePropertyAccessInfos(access_infos, access_mode, result);
for (PropertyAccessInfo const& info : *result) {
if (info.IsInvalid()) return false;
}
for (PropertyAccessInfo& info : *result) {
info.RecordDependencies(dependencies());
}
return true;
}
void AccessInfoFactory::MergePropertyAccessInfos(
ZoneVector<PropertyAccessInfo> infos, AccessMode access_mode,
ZoneVector<PropertyAccessInfo>* result) const {
DCHECK(result->empty());
for (auto it = infos.begin(), end = infos.end(); it != end; ++it) {
bool merged = false;
for (auto ot = it + 1; ot != end; ++ot) {
if (ot->Merge(&(*it), access_mode, zone())) {
merged = true;
break;
}
}
if (!merged) result->push_back(*it);
}
CHECK(!result->empty());
}
Isolate* AccessInfoFactory::isolate() const { return broker()->isolate(); }
namespace {
Maybe<ElementsKind> GeneralizeElementsKind(ElementsKind this_kind,
ElementsKind that_kind) {
if (IsHoleyElementsKind(this_kind)) {
that_kind = GetHoleyElementsKind(that_kind);
} else if (IsHoleyElementsKind(that_kind)) {
this_kind = GetHoleyElementsKind(this_kind);
}
if (this_kind == that_kind) return Just(this_kind);
if (IsDoubleElementsKind(that_kind) == IsDoubleElementsKind(this_kind)) {
if (IsMoreGeneralElementsKindTransition(that_kind, this_kind)) {
return Just(this_kind);
}
if (IsMoreGeneralElementsKindTransition(this_kind, that_kind)) {
return Just(that_kind);
}
}
return Nothing<ElementsKind>();
}
} // namespace
base::Optional<ElementAccessInfo> AccessInfoFactory::ConsolidateElementLoad(
ElementAccessFeedback const& feedback) const {
if (feedback.transition_groups().empty()) return base::nullopt;
DCHECK(!feedback.transition_groups().front().empty());
MapRef first_map(broker(), feedback.transition_groups().front().front());
InstanceType instance_type = first_map.instance_type();
ElementsKind elements_kind = first_map.elements_kind();
ZoneVector<Handle<Map>> maps(zone());
for (auto const& group : feedback.transition_groups()) {
for (Handle<Map> map_handle : group) {
MapRef map(broker(), map_handle);
if (map.instance_type() != instance_type ||
!CanInlineElementAccess(map)) {
return base::nullopt;
}
if (!GeneralizeElementsKind(elements_kind, map.elements_kind())
.To(&elements_kind)) {
return base::nullopt;
}
maps.push_back(map.object());
}
}
return ElementAccessInfo(std::move(maps), elements_kind, zone());
}
PropertyAccessInfo AccessInfoFactory::LookupSpecialFieldAccessor(
Handle<Map> map, Handle<Name> name) const {
// Check for String::length field accessor.
if (map->IsStringMap()) {
if (Name::Equals(isolate(), name, isolate()->factory()->length_string())) {
return PropertyAccessInfo::StringLength(zone(), map);
}
return PropertyAccessInfo::Invalid(zone());
}
// Check for special JSObject field accessors.
FieldIndex field_index;
if (Accessors::IsJSObjectFieldAccessor(isolate(), map, name, &field_index)) {
Type field_type = Type::NonInternal();
Representation field_representation = Representation::Tagged();
if (map->IsJSArrayMap()) {
DCHECK(
Name::Equals(isolate(), isolate()->factory()->length_string(), name));
// The JSArray::length property is a smi in the range
// [0, FixedDoubleArray::kMaxLength] in case of fast double
// elements, a smi in the range [0, FixedArray::kMaxLength]
// in case of other fast elements, and [0, kMaxUInt32] in
// case of other arrays.
if (IsDoubleElementsKind(map->elements_kind())) {
field_type = type_cache_->kFixedDoubleArrayLengthType;
field_representation = Representation::Smi();
} else if (IsFastElementsKind(map->elements_kind())) {
field_type = type_cache_->kFixedArrayLengthType;
field_representation = Representation::Smi();
} else {
field_type = type_cache_->kJSArrayLengthType;
}
}
// Special fields are always mutable.
return PropertyAccessInfo::DataField(zone(), map, {{}, zone()}, field_index,
field_representation, field_type, map);
}
return PropertyAccessInfo::Invalid(zone());
}
PropertyAccessInfo AccessInfoFactory::LookupTransition(
Handle<Map> map, Handle<Name> name, MaybeHandle<JSObject> holder) const {
// Check if the {map} has a data transition with the given {name}.
Map transition =
TransitionsAccessor(isolate(), map).SearchTransition(*name, kData, NONE);
if (transition.is_null()) {
return PropertyAccessInfo::Invalid(zone());
}
Handle<Map> transition_map(transition, isolate());
InternalIndex const number = transition_map->LastAdded();
PropertyDetails const details =
transition_map->instance_descriptors().GetDetails(number);
// Don't bother optimizing stores to read-only properties.
if (details.IsReadOnly()) {
return PropertyAccessInfo::Invalid(zone());
}
// TODO(bmeurer): Handle transition to data constant?
if (details.location() != kField) {
return PropertyAccessInfo::Invalid(zone());
}
int const index = details.field_index();
Representation details_representation = details.representation();
FieldIndex field_index = FieldIndex::ForPropertyIndex(*transition_map, index,
details_representation);
Type field_type = Type::NonInternal();
MaybeHandle<Map> field_map;
MapRef transition_map_ref(broker(), transition_map);
ZoneVector<CompilationDependency const*> unrecorded_dependencies(zone());
if (details_representation.IsSmi()) {
field_type = Type::SignedSmall();
transition_map_ref.SerializeOwnDescriptor(number);
unrecorded_dependencies.push_back(
dependencies()->FieldRepresentationDependencyOffTheRecord(
transition_map_ref, number));
} else if (details_representation.IsDouble()) {
field_type = type_cache_->kFloat64;
if (!FLAG_unbox_double_fields) {
transition_map_ref.SerializeOwnDescriptor(number);
unrecorded_dependencies.push_back(
dependencies()->FieldRepresentationDependencyOffTheRecord(
transition_map_ref, number));
}
} else if (details_representation.IsHeapObject()) {
// Extract the field type from the property details (make sure its
// representation is TaggedPointer to reflect the heap object case).
Handle<FieldType> descriptors_field_type(
transition_map->instance_descriptors().GetFieldType(number), isolate());
if (descriptors_field_type->IsNone()) {
// Store is not safe if the field type was cleared.
return PropertyAccessInfo::Invalid(zone());
}
transition_map_ref.SerializeOwnDescriptor(number);
unrecorded_dependencies.push_back(
dependencies()->FieldRepresentationDependencyOffTheRecord(
transition_map_ref, number));
if (descriptors_field_type->IsClass()) {
unrecorded_dependencies.push_back(
dependencies()->FieldTypeDependencyOffTheRecord(transition_map_ref,
number));
// Remember the field map, and try to infer a useful type.
Handle<Map> map(descriptors_field_type->AsClass(), isolate());
field_type = Type::For(MapRef(broker(), map));
field_map = MaybeHandle<Map>(map);
}
}
unrecorded_dependencies.push_back(
dependencies()->TransitionDependencyOffTheRecord(
MapRef(broker(), transition_map)));
transition_map_ref.SerializeBackPointer(); // For BuildPropertyStore.
// Transitioning stores *may* store to const fields. The resulting
// DataConstant access infos can be distinguished from later, i.e. redundant,
// stores to the same constant field by the presence of a transition map.
switch (details.constness()) {
case PropertyConstness::kMutable:
return PropertyAccessInfo::DataField(
zone(), map, std::move(unrecorded_dependencies), field_index,
details_representation, field_type, transition_map, field_map, holder,
transition_map);
case PropertyConstness::kConst:
return PropertyAccessInfo::DataConstant(
zone(), map, std::move(unrecorded_dependencies), field_index,
details_representation, field_type, transition_map, field_map, holder,
transition_map);
}
UNREACHABLE();
}
} // namespace compiler
} // namespace internal
} // namespace v8
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