blob: 7888f5a21e3442e097dba37a2e91a8bba54fb975 [file] [log] [blame]
// Copyright 2016 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/compiler/load-elimination.h"
#include "src/compiler/common-operator.h"
#include "src/compiler/js-graph.h"
#include "src/compiler/node-properties.h"
#include "src/compiler/simplified-operator.h"
#include "src/factory.h"
#include "src/objects-inl.h"
namespace v8 {
namespace internal {
namespace compiler {
namespace {
bool IsRename(Node* node) {
switch (node->opcode()) {
case IrOpcode::kFinishRegion:
case IrOpcode::kTypeGuard:
return true;
default:
return false;
}
}
Node* ResolveRenames(Node* node) {
while (IsRename(node)) {
node = node->InputAt(0);
}
return node;
}
bool MayAlias(Node* a, Node* b) {
if (a == b) return true;
if (!NodeProperties::GetType(a)->Maybe(NodeProperties::GetType(b))) {
return false;
}
switch (b->opcode()) {
case IrOpcode::kAllocate: {
switch (a->opcode()) {
case IrOpcode::kAllocate:
case IrOpcode::kHeapConstant:
case IrOpcode::kParameter:
return false;
default:
break;
}
break;
}
case IrOpcode::kFinishRegion:
case IrOpcode::kTypeGuard:
return MayAlias(a, b->InputAt(0));
default:
break;
}
switch (a->opcode()) {
case IrOpcode::kAllocate: {
switch (b->opcode()) {
case IrOpcode::kHeapConstant:
case IrOpcode::kParameter:
return false;
default:
break;
}
break;
}
case IrOpcode::kFinishRegion:
case IrOpcode::kTypeGuard:
return MayAlias(a->InputAt(0), b);
default:
break;
}
return true;
}
bool MustAlias(Node* a, Node* b) {
return ResolveRenames(a) == ResolveRenames(b);
}
} // namespace
Reduction LoadElimination::Reduce(Node* node) {
if (FLAG_trace_turbo_load_elimination) {
if (node->op()->EffectInputCount() > 0) {
PrintF(" visit #%d:%s", node->id(), node->op()->mnemonic());
if (node->op()->ValueInputCount() > 0) {
PrintF("(");
for (int i = 0; i < node->op()->ValueInputCount(); ++i) {
if (i > 0) PrintF(", ");
Node* const value = NodeProperties::GetValueInput(node, i);
PrintF("#%d:%s", value->id(), value->op()->mnemonic());
}
PrintF(")");
}
PrintF("\n");
for (int i = 0; i < node->op()->EffectInputCount(); ++i) {
Node* const effect = NodeProperties::GetEffectInput(node, i);
if (AbstractState const* const state = node_states_.Get(effect)) {
PrintF(" state[%i]: #%d:%s\n", i, effect->id(),
effect->op()->mnemonic());
state->Print();
} else {
PrintF(" no state[%i]: #%d:%s\n", i, effect->id(),
effect->op()->mnemonic());
}
}
}
}
switch (node->opcode()) {
case IrOpcode::kArrayBufferWasNeutered:
return ReduceArrayBufferWasNeutered(node);
case IrOpcode::kMapGuard:
return ReduceMapGuard(node);
case IrOpcode::kCheckMaps:
return ReduceCheckMaps(node);
case IrOpcode::kCompareMaps:
return ReduceCompareMaps(node);
case IrOpcode::kEnsureWritableFastElements:
return ReduceEnsureWritableFastElements(node);
case IrOpcode::kMaybeGrowFastElements:
return ReduceMaybeGrowFastElements(node);
case IrOpcode::kTransitionElementsKind:
return ReduceTransitionElementsKind(node);
case IrOpcode::kLoadField:
return ReduceLoadField(node);
case IrOpcode::kStoreField:
return ReduceStoreField(node);
case IrOpcode::kLoadElement:
return ReduceLoadElement(node);
case IrOpcode::kStoreElement:
return ReduceStoreElement(node);
case IrOpcode::kTransitionAndStoreElement:
return ReduceTransitionAndStoreElement(node);
case IrOpcode::kStoreTypedElement:
return ReduceStoreTypedElement(node);
case IrOpcode::kEffectPhi:
return ReduceEffectPhi(node);
case IrOpcode::kDead:
break;
case IrOpcode::kStart:
return ReduceStart(node);
default:
return ReduceOtherNode(node);
}
return NoChange();
}
namespace {
bool LoadEliminationIsCompatibleCheck(Node const* a, Node const* b) {
if (a->op() != b->op()) return false;
for (int i = a->op()->ValueInputCount(); --i >= 0;) {
if (!MustAlias(a->InputAt(i), b->InputAt(i))) return false;
}
return true;
}
} // namespace
Node* LoadElimination::AbstractChecks::Lookup(Node* node) const {
for (Node* const check : nodes_) {
if (check && !check->IsDead() &&
LoadEliminationIsCompatibleCheck(check, node)) {
return check;
}
}
return nullptr;
}
bool LoadElimination::AbstractChecks::Equals(AbstractChecks const* that) const {
if (this == that) return true;
for (size_t i = 0; i < arraysize(nodes_); ++i) {
if (Node* this_node = this->nodes_[i]) {
for (size_t j = 0;; ++j) {
if (j == arraysize(nodes_)) return false;
if (that->nodes_[j] == this_node) break;
}
}
}
for (size_t i = 0; i < arraysize(nodes_); ++i) {
if (Node* that_node = that->nodes_[i]) {
for (size_t j = 0;; ++j) {
if (j == arraysize(nodes_)) return false;
if (this->nodes_[j] == that_node) break;
}
}
}
return true;
}
LoadElimination::AbstractChecks const* LoadElimination::AbstractChecks::Merge(
AbstractChecks const* that, Zone* zone) const {
if (this->Equals(that)) return this;
AbstractChecks* copy = new (zone) AbstractChecks(zone);
for (Node* const this_node : this->nodes_) {
if (this_node == nullptr) continue;
for (Node* const that_node : that->nodes_) {
if (this_node == that_node) {
copy->nodes_[copy->next_index_++] = this_node;
break;
}
}
}
copy->next_index_ %= arraysize(nodes_);
return copy;
}
void LoadElimination::AbstractChecks::Print() const {
for (Node* const node : nodes_) {
if (node != nullptr) {
PrintF(" #%d:%s\n", node->id(), node->op()->mnemonic());
}
}
}
namespace {
bool IsCompatible(MachineRepresentation r1, MachineRepresentation r2) {
if (r1 == r2) return true;
return IsAnyTagged(r1) && IsAnyTagged(r2);
}
} // namespace
Node* LoadElimination::AbstractElements::Lookup(
Node* object, Node* index, MachineRepresentation representation) const {
for (Element const element : elements_) {
if (element.object == nullptr) continue;
DCHECK_NOT_NULL(element.index);
DCHECK_NOT_NULL(element.value);
if (MustAlias(object, element.object) && MustAlias(index, element.index) &&
IsCompatible(representation, element.representation)) {
return element.value;
}
}
return nullptr;
}
LoadElimination::AbstractElements const*
LoadElimination::AbstractElements::Kill(Node* object, Node* index,
Zone* zone) const {
for (Element const element : this->elements_) {
if (element.object == nullptr) continue;
if (MayAlias(object, element.object)) {
AbstractElements* that = new (zone) AbstractElements(zone);
for (Element const element : this->elements_) {
if (element.object == nullptr) continue;
DCHECK_NOT_NULL(element.index);
DCHECK_NOT_NULL(element.value);
if (!MayAlias(object, element.object) ||
!NodeProperties::GetType(index)->Maybe(
NodeProperties::GetType(element.index))) {
that->elements_[that->next_index_++] = element;
}
}
that->next_index_ %= arraysize(elements_);
return that;
}
}
return this;
}
bool LoadElimination::AbstractElements::Equals(
AbstractElements const* that) const {
if (this == that) return true;
for (size_t i = 0; i < arraysize(elements_); ++i) {
Element this_element = this->elements_[i];
if (this_element.object == nullptr) continue;
for (size_t j = 0;; ++j) {
if (j == arraysize(elements_)) return false;
Element that_element = that->elements_[j];
if (this_element.object == that_element.object &&
this_element.index == that_element.index &&
this_element.value == that_element.value) {
break;
}
}
}
for (size_t i = 0; i < arraysize(elements_); ++i) {
Element that_element = that->elements_[i];
if (that_element.object == nullptr) continue;
for (size_t j = 0;; ++j) {
if (j == arraysize(elements_)) return false;
Element this_element = this->elements_[j];
if (that_element.object == this_element.object &&
that_element.index == this_element.index &&
that_element.value == this_element.value) {
break;
}
}
}
return true;
}
LoadElimination::AbstractElements const*
LoadElimination::AbstractElements::Merge(AbstractElements const* that,
Zone* zone) const {
if (this->Equals(that)) return this;
AbstractElements* copy = new (zone) AbstractElements(zone);
for (Element const this_element : this->elements_) {
if (this_element.object == nullptr) continue;
for (Element const that_element : that->elements_) {
if (this_element.object == that_element.object &&
this_element.index == that_element.index &&
this_element.value == that_element.value) {
copy->elements_[copy->next_index_++] = this_element;
break;
}
}
}
copy->next_index_ %= arraysize(elements_);
return copy;
}
void LoadElimination::AbstractElements::Print() const {
for (Element const& element : elements_) {
if (element.object) {
PrintF(" #%d:%s @ #%d:%s -> #%d:%s\n", element.object->id(),
element.object->op()->mnemonic(), element.index->id(),
element.index->op()->mnemonic(), element.value->id(),
element.value->op()->mnemonic());
}
}
}
Node* LoadElimination::AbstractField::Lookup(Node* object) const {
for (auto pair : info_for_node_) {
if (MustAlias(object, pair.first)) return pair.second.value;
}
return nullptr;
}
namespace {
bool MayAlias(MaybeHandle<Name> x, MaybeHandle<Name> y) {
if (!x.address()) return true;
if (!y.address()) return true;
if (x.address() != y.address()) return false;
return true;
}
} // namespace
class LoadElimination::AliasStateInfo {
public:
AliasStateInfo(const AbstractState* state, Node* object, Handle<Map> map)
: state_(state), object_(object), map_(map) {}
AliasStateInfo(const AbstractState* state, Node* object)
: state_(state), object_(object) {}
bool MayAlias(Node* other) const;
private:
const AbstractState* state_;
Node* object_;
MaybeHandle<Map> map_;
};
LoadElimination::AbstractField const* LoadElimination::AbstractField::Kill(
const AliasStateInfo& alias_info, MaybeHandle<Name> name,
Zone* zone) const {
for (auto pair : this->info_for_node_) {
if (alias_info.MayAlias(pair.first)) {
AbstractField* that = new (zone) AbstractField(zone);
for (auto pair : this->info_for_node_) {
if (!alias_info.MayAlias(pair.first) ||
!MayAlias(name, pair.second.name)) {
that->info_for_node_.insert(pair);
}
}
return that;
}
}
return this;
}
void LoadElimination::AbstractField::Print() const {
for (auto pair : info_for_node_) {
PrintF(" #%d:%s -> #%d:%s\n", pair.first->id(),
pair.first->op()->mnemonic(), pair.second.value->id(),
pair.second.value->op()->mnemonic());
}
}
LoadElimination::AbstractMaps::AbstractMaps(Zone* zone)
: info_for_node_(zone) {}
LoadElimination::AbstractMaps::AbstractMaps(Node* object,
ZoneHandleSet<Map> maps, Zone* zone)
: info_for_node_(zone) {
object = ResolveRenames(object);
info_for_node_.insert(std::make_pair(object, maps));
}
bool LoadElimination::AbstractMaps::Lookup(
Node* object, ZoneHandleSet<Map>* object_maps) const {
auto it = info_for_node_.find(ResolveRenames(object));
if (it == info_for_node_.end()) return false;
*object_maps = it->second;
return true;
}
LoadElimination::AbstractMaps const* LoadElimination::AbstractMaps::Kill(
const AliasStateInfo& alias_info, Zone* zone) const {
for (auto pair : this->info_for_node_) {
if (alias_info.MayAlias(pair.first)) {
AbstractMaps* that = new (zone) AbstractMaps(zone);
for (auto pair : this->info_for_node_) {
if (!alias_info.MayAlias(pair.first)) that->info_for_node_.insert(pair);
}
return that;
}
}
return this;
}
LoadElimination::AbstractMaps const* LoadElimination::AbstractMaps::Merge(
AbstractMaps const* that, Zone* zone) const {
if (this->Equals(that)) return this;
AbstractMaps* copy = new (zone) AbstractMaps(zone);
for (auto this_it : this->info_for_node_) {
Node* this_object = this_it.first;
ZoneHandleSet<Map> this_maps = this_it.second;
auto that_it = that->info_for_node_.find(this_object);
if (that_it != that->info_for_node_.end() && that_it->second == this_maps) {
copy->info_for_node_.insert(this_it);
}
}
return copy;
}
LoadElimination::AbstractMaps const* LoadElimination::AbstractMaps::Extend(
Node* object, ZoneHandleSet<Map> maps, Zone* zone) const {
AbstractMaps* that = new (zone) AbstractMaps(zone);
that->info_for_node_ = this->info_for_node_;
object = ResolveRenames(object);
that->info_for_node_[object] = maps;
return that;
}
void LoadElimination::AbstractMaps::Print() const {
for (auto pair : info_for_node_) {
PrintF(" #%d:%s\n", pair.first->id(), pair.first->op()->mnemonic());
OFStream os(stdout);
ZoneHandleSet<Map> const& maps = pair.second;
for (size_t i = 0; i < maps.size(); ++i) {
os << " - " << Brief(*maps[i]) << "\n";
}
}
}
bool LoadElimination::AbstractState::Equals(AbstractState const* that) const {
if (this->checks_) {
if (!that->checks_ || !that->checks_->Equals(this->checks_)) {
return false;
}
} else if (that->checks_) {
return false;
}
if (this->elements_) {
if (!that->elements_ || !that->elements_->Equals(this->elements_)) {
return false;
}
} else if (that->elements_) {
return false;
}
for (size_t i = 0u; i < arraysize(fields_); ++i) {
AbstractField const* this_field = this->fields_[i];
AbstractField const* that_field = that->fields_[i];
if (this_field) {
if (!that_field || !that_field->Equals(this_field)) return false;
} else if (that_field) {
return false;
}
}
if (this->maps_) {
if (!that->maps_ || !that->maps_->Equals(this->maps_)) {
return false;
}
} else if (that->maps_) {
return false;
}
return true;
}
void LoadElimination::AbstractState::Merge(AbstractState const* that,
Zone* zone) {
// Merge the information we have about the checks.
if (this->checks_) {
this->checks_ =
that->checks_ ? that->checks_->Merge(this->checks_, zone) : nullptr;
}
// Merge the information we have about the elements.
if (this->elements_) {
this->elements_ = that->elements_
? that->elements_->Merge(this->elements_, zone)
: nullptr;
}
// Merge the information we have about the fields.
for (size_t i = 0; i < arraysize(fields_); ++i) {
if (this->fields_[i]) {
if (that->fields_[i]) {
this->fields_[i] = this->fields_[i]->Merge(that->fields_[i], zone);
} else {
this->fields_[i] = nullptr;
}
}
}
// Merge the information we have about the maps.
if (this->maps_) {
this->maps_ = that->maps_ ? that->maps_->Merge(this->maps_, zone) : nullptr;
}
}
Node* LoadElimination::AbstractState::LookupCheck(Node* node) const {
return this->checks_ ? this->checks_->Lookup(node) : nullptr;
}
LoadElimination::AbstractState const* LoadElimination::AbstractState::AddCheck(
Node* node, Zone* zone) const {
AbstractState* that = new (zone) AbstractState(*this);
if (that->checks_) {
that->checks_ = that->checks_->Extend(node, zone);
} else {
that->checks_ = new (zone) AbstractChecks(node, zone);
}
return that;
}
bool LoadElimination::AbstractState::LookupMaps(
Node* object, ZoneHandleSet<Map>* object_map) const {
return this->maps_ && this->maps_->Lookup(object, object_map);
}
LoadElimination::AbstractState const* LoadElimination::AbstractState::SetMaps(
Node* object, ZoneHandleSet<Map> maps, Zone* zone) const {
AbstractState* that = new (zone) AbstractState(*this);
if (that->maps_) {
that->maps_ = that->maps_->Extend(object, maps, zone);
} else {
that->maps_ = new (zone) AbstractMaps(object, maps, zone);
}
return that;
}
LoadElimination::AbstractState const* LoadElimination::AbstractState::KillMaps(
const AliasStateInfo& alias_info, Zone* zone) const {
if (this->maps_) {
AbstractMaps const* that_maps = this->maps_->Kill(alias_info, zone);
if (this->maps_ != that_maps) {
AbstractState* that = new (zone) AbstractState(*this);
that->maps_ = that_maps;
return that;
}
}
return this;
}
LoadElimination::AbstractState const* LoadElimination::AbstractState::KillMaps(
Node* object, Zone* zone) const {
AliasStateInfo alias_info(this, object);
return KillMaps(alias_info, zone);
}
Node* LoadElimination::AbstractState::LookupElement(
Node* object, Node* index, MachineRepresentation representation) const {
if (this->elements_) {
return this->elements_->Lookup(object, index, representation);
}
return nullptr;
}
LoadElimination::AbstractState const*
LoadElimination::AbstractState::AddElement(Node* object, Node* index,
Node* value,
MachineRepresentation representation,
Zone* zone) const {
AbstractState* that = new (zone) AbstractState(*this);
if (that->elements_) {
that->elements_ =
that->elements_->Extend(object, index, value, representation, zone);
} else {
that->elements_ =
new (zone) AbstractElements(object, index, value, representation, zone);
}
return that;
}
LoadElimination::AbstractState const*
LoadElimination::AbstractState::KillElement(Node* object, Node* index,
Zone* zone) const {
if (this->elements_) {
AbstractElements const* that_elements =
this->elements_->Kill(object, index, zone);
if (this->elements_ != that_elements) {
AbstractState* that = new (zone) AbstractState(*this);
that->elements_ = that_elements;
return that;
}
}
return this;
}
LoadElimination::AbstractState const* LoadElimination::AbstractState::AddField(
Node* object, size_t index, Node* value, MaybeHandle<Name> name,
Zone* zone) const {
AbstractState* that = new (zone) AbstractState(*this);
if (that->fields_[index]) {
that->fields_[index] =
that->fields_[index]->Extend(object, value, name, zone);
} else {
that->fields_[index] = new (zone) AbstractField(object, value, name, zone);
}
return that;
}
LoadElimination::AbstractState const* LoadElimination::AbstractState::KillField(
Node* object, size_t index, MaybeHandle<Name> name, Zone* zone) const {
AliasStateInfo alias_info(this, object);
return KillField(alias_info, index, name, zone);
}
LoadElimination::AbstractState const* LoadElimination::AbstractState::KillField(
const AliasStateInfo& alias_info, size_t index, MaybeHandle<Name> name,
Zone* zone) const {
if (AbstractField const* this_field = this->fields_[index]) {
this_field = this_field->Kill(alias_info, name, zone);
if (this->fields_[index] != this_field) {
AbstractState* that = new (zone) AbstractState(*this);
that->fields_[index] = this_field;
return that;
}
}
return this;
}
LoadElimination::AbstractState const*
LoadElimination::AbstractState::KillFields(Node* object, MaybeHandle<Name> name,
Zone* zone) const {
AliasStateInfo alias_info(this, object);
for (size_t i = 0;; ++i) {
if (i == arraysize(fields_)) return this;
if (AbstractField const* this_field = this->fields_[i]) {
AbstractField const* that_field =
this_field->Kill(alias_info, name, zone);
if (that_field != this_field) {
AbstractState* that = new (zone) AbstractState(*this);
that->fields_[i] = that_field;
while (++i < arraysize(fields_)) {
if (this->fields_[i] != nullptr) {
that->fields_[i] = this->fields_[i]->Kill(alias_info, name, zone);
}
}
return that;
}
}
}
}
Node* LoadElimination::AbstractState::LookupField(Node* object,
size_t index) const {
if (AbstractField const* this_field = this->fields_[index]) {
return this_field->Lookup(object);
}
return nullptr;
}
bool LoadElimination::AliasStateInfo::MayAlias(Node* other) const {
// Decide aliasing based on the node kinds.
if (!compiler::MayAlias(object_, other)) {
return false;
}
// Decide aliasing based on maps (if available).
Handle<Map> map;
if (map_.ToHandle(&map)) {
ZoneHandleSet<Map> other_maps;
if (state_->LookupMaps(other, &other_maps) && other_maps.size() == 1) {
if (map.address() != other_maps.at(0).address()) {
return false;
}
}
}
return true;
}
void LoadElimination::AbstractState::Print() const {
if (checks_) {
PrintF(" checks:\n");
checks_->Print();
}
if (maps_) {
PrintF(" maps:\n");
maps_->Print();
}
if (elements_) {
PrintF(" elements:\n");
elements_->Print();
}
for (size_t i = 0; i < arraysize(fields_); ++i) {
if (AbstractField const* const field = fields_[i]) {
PrintF(" field %zu:\n", i);
field->Print();
}
}
}
LoadElimination::AbstractState const*
LoadElimination::AbstractStateForEffectNodes::Get(Node* node) const {
size_t const id = node->id();
if (id < info_for_node_.size()) return info_for_node_[id];
return nullptr;
}
void LoadElimination::AbstractStateForEffectNodes::Set(
Node* node, AbstractState const* state) {
size_t const id = node->id();
if (id >= info_for_node_.size()) info_for_node_.resize(id + 1, nullptr);
info_for_node_[id] = state;
}
Reduction LoadElimination::ReduceArrayBufferWasNeutered(Node* node) {
Node* const effect = NodeProperties::GetEffectInput(node);
AbstractState const* state = node_states_.Get(effect);
if (state == nullptr) return NoChange();
if (Node* const check = state->LookupCheck(node)) {
ReplaceWithValue(node, check, effect);
return Replace(check);
}
state = state->AddCheck(node, zone());
return UpdateState(node, state);
}
Reduction LoadElimination::ReduceMapGuard(Node* node) {
ZoneHandleSet<Map> const maps = MapGuardMapsOf(node->op()).maps();
Node* const object = NodeProperties::GetValueInput(node, 0);
Node* const effect = NodeProperties::GetEffectInput(node);
AbstractState const* state = node_states_.Get(effect);
if (state == nullptr) return NoChange();
ZoneHandleSet<Map> object_maps;
if (state->LookupMaps(object, &object_maps)) {
if (maps.contains(object_maps)) return Replace(effect);
// TODO(turbofan): Compute the intersection.
}
state = state->SetMaps(object, maps, zone());
return UpdateState(node, state);
}
Reduction LoadElimination::ReduceCheckMaps(Node* node) {
ZoneHandleSet<Map> const maps = CheckMapsParametersOf(node->op()).maps();
Node* const object = NodeProperties::GetValueInput(node, 0);
Node* const effect = NodeProperties::GetEffectInput(node);
AbstractState const* state = node_states_.Get(effect);
if (state == nullptr) return NoChange();
ZoneHandleSet<Map> object_maps;
if (state->LookupMaps(object, &object_maps)) {
if (maps.contains(object_maps)) return Replace(effect);
// TODO(turbofan): Compute the intersection.
}
state = state->SetMaps(object, maps, zone());
return UpdateState(node, state);
}
Reduction LoadElimination::ReduceCompareMaps(Node* node) {
ZoneHandleSet<Map> const maps = CompareMapsParametersOf(node->op()).maps();
Node* const object = NodeProperties::GetValueInput(node, 0);
Node* const effect = NodeProperties::GetEffectInput(node);
AbstractState const* state = node_states_.Get(effect);
if (state == nullptr) return NoChange();
ZoneHandleSet<Map> object_maps;
if (state->LookupMaps(object, &object_maps)) {
if (maps.contains(object_maps)) {
Node* value = jsgraph()->TrueConstant();
ReplaceWithValue(node, value, effect);
return Replace(value);
}
// TODO(turbofan): Compute the intersection.
}
return UpdateState(node, state);
}
Reduction LoadElimination::ReduceEnsureWritableFastElements(Node* node) {
Node* const object = NodeProperties::GetValueInput(node, 0);
Node* const elements = NodeProperties::GetValueInput(node, 1);
Node* const effect = NodeProperties::GetEffectInput(node);
AbstractState const* state = node_states_.Get(effect);
if (state == nullptr) return NoChange();
// Check if the {elements} already have the fixed array map.
ZoneHandleSet<Map> elements_maps;
ZoneHandleSet<Map> fixed_array_maps(factory()->fixed_array_map());
if (state->LookupMaps(elements, &elements_maps) &&
fixed_array_maps.contains(elements_maps)) {
ReplaceWithValue(node, elements, effect);
return Replace(elements);
}
// We know that the resulting elements have the fixed array map.
state = state->SetMaps(node, fixed_array_maps, zone());
// Kill the previous elements on {object}.
state = state->KillField(object, FieldIndexOf(JSObject::kElementsOffset),
MaybeHandle<Name>(), zone());
// Add the new elements on {object}.
state = state->AddField(object, FieldIndexOf(JSObject::kElementsOffset), node,
MaybeHandle<Name>(), zone());
return UpdateState(node, state);
}
Reduction LoadElimination::ReduceMaybeGrowFastElements(Node* node) {
GrowFastElementsParameters params = GrowFastElementsParametersOf(node->op());
Node* const object = NodeProperties::GetValueInput(node, 0);
Node* const effect = NodeProperties::GetEffectInput(node);
AbstractState const* state = node_states_.Get(effect);
if (state == nullptr) return NoChange();
if (params.mode() == GrowFastElementsMode::kDoubleElements) {
// We know that the resulting elements have the fixed double array map.
state = state->SetMaps(
node, ZoneHandleSet<Map>(factory()->fixed_double_array_map()), zone());
} else {
// We know that the resulting elements have the fixed array map.
state = state->SetMaps(
node, ZoneHandleSet<Map>(factory()->fixed_array_map()), zone());
}
// Kill the previous elements on {object}.
state = state->KillField(object, FieldIndexOf(JSObject::kElementsOffset),
MaybeHandle<Name>(), zone());
// Add the new elements on {object}.
state = state->AddField(object, FieldIndexOf(JSObject::kElementsOffset), node,
MaybeHandle<Name>(), zone());
return UpdateState(node, state);
}
Reduction LoadElimination::ReduceTransitionElementsKind(Node* node) {
ElementsTransition transition = ElementsTransitionOf(node->op());
Node* const object = NodeProperties::GetValueInput(node, 0);
Handle<Map> source_map(transition.source());
Handle<Map> target_map(transition.target());
Node* const effect = NodeProperties::GetEffectInput(node);
AbstractState const* state = node_states_.Get(effect);
if (state == nullptr) return NoChange();
switch (transition.mode()) {
case ElementsTransition::kFastTransition:
break;
case ElementsTransition::kSlowTransition:
// Kill the elements as well.
AliasStateInfo alias_info(state, object, source_map);
state =
state->KillField(alias_info, FieldIndexOf(JSObject::kElementsOffset),
MaybeHandle<Name>(), zone());
break;
}
ZoneHandleSet<Map> object_maps;
if (state->LookupMaps(object, &object_maps)) {
if (ZoneHandleSet<Map>(target_map).contains(object_maps)) {
// The {object} already has the {target_map}, so this TransitionElements
// {node} is fully redundant (independent of what {source_map} is).
return Replace(effect);
}
if (object_maps.contains(ZoneHandleSet<Map>(source_map))) {
object_maps.remove(source_map, zone());
object_maps.insert(target_map, zone());
AliasStateInfo alias_info(state, object, source_map);
state = state->KillMaps(alias_info, zone());
state = state->SetMaps(object, object_maps, zone());
}
} else {
AliasStateInfo alias_info(state, object, source_map);
state = state->KillMaps(alias_info, zone());
}
return UpdateState(node, state);
}
Reduction LoadElimination::ReduceTransitionAndStoreElement(Node* node) {
Node* const object = NodeProperties::GetValueInput(node, 0);
Handle<Map> double_map(DoubleMapParameterOf(node->op()));
Handle<Map> fast_map(FastMapParameterOf(node->op()));
Node* const effect = NodeProperties::GetEffectInput(node);
AbstractState const* state = node_states_.Get(effect);
if (state == nullptr) return NoChange();
// We need to add the double and fast maps to the set of possible maps for
// this object, because we don't know which of those we'll transition to.
// Additionally, we should kill all alias information.
ZoneHandleSet<Map> object_maps;
if (state->LookupMaps(object, &object_maps)) {
object_maps.insert(double_map, zone());
object_maps.insert(fast_map, zone());
state = state->KillMaps(object, zone());
state = state->SetMaps(object, object_maps, zone());
}
// Kill the elements as well.
state = state->KillField(object, FieldIndexOf(JSObject::kElementsOffset),
MaybeHandle<Name>(), zone());
return UpdateState(node, state);
}
Reduction LoadElimination::ReduceLoadField(Node* node) {
FieldAccess const& access = FieldAccessOf(node->op());
Node* const object = NodeProperties::GetValueInput(node, 0);
Node* const effect = NodeProperties::GetEffectInput(node);
AbstractState const* state = node_states_.Get(effect);
if (state == nullptr) return NoChange();
if (access.offset == HeapObject::kMapOffset &&
access.base_is_tagged == kTaggedBase) {
DCHECK(IsAnyTagged(access.machine_type.representation()));
ZoneHandleSet<Map> object_maps;
if (state->LookupMaps(object, &object_maps) && object_maps.size() == 1) {
Node* value = jsgraph()->HeapConstant(object_maps[0]);
NodeProperties::SetType(value, Type::OtherInternal());
ReplaceWithValue(node, value, effect);
return Replace(value);
}
} else {
int field_index = FieldIndexOf(access);
if (field_index >= 0) {
if (Node* replacement = state->LookupField(object, field_index)) {
// Make sure we don't resurrect dead {replacement} nodes.
// Skip lowering if the type of the {replacement} node is not a subtype
// of the original {node}'s type.
// TODO(tebbi): We should insert a {TypeGuard} for the intersection of
// these two types here once we properly handle {Type::None} everywhere.
if (!replacement->IsDead() && NodeProperties::GetType(replacement)
->Is(NodeProperties::GetType(node))) {
ReplaceWithValue(node, replacement, effect);
return Replace(replacement);
}
}
state = state->AddField(object, field_index, node, access.name, zone());
}
}
Handle<Map> field_map;
if (access.map.ToHandle(&field_map)) {
state = state->SetMaps(node, ZoneHandleSet<Map>(field_map), zone());
}
return UpdateState(node, state);
}
Reduction LoadElimination::ReduceStoreField(Node* node) {
FieldAccess const& access = FieldAccessOf(node->op());
Node* const object = NodeProperties::GetValueInput(node, 0);
Node* const new_value = NodeProperties::GetValueInput(node, 1);
Node* const effect = NodeProperties::GetEffectInput(node);
AbstractState const* state = node_states_.Get(effect);
if (state == nullptr) return NoChange();
if (access.offset == HeapObject::kMapOffset &&
access.base_is_tagged == kTaggedBase) {
DCHECK(IsAnyTagged(access.machine_type.representation()));
// Kill all potential knowledge about the {object}s map.
state = state->KillMaps(object, zone());
Type* const new_value_type = NodeProperties::GetType(new_value);
if (new_value_type->IsHeapConstant()) {
// Record the new {object} map information.
ZoneHandleSet<Map> object_maps(
bit_cast<Handle<Map>>(new_value_type->AsHeapConstant()->Value()));
state = state->SetMaps(object, object_maps, zone());
}
} else {
int field_index = FieldIndexOf(access);
if (field_index >= 0) {
Node* const old_value = state->LookupField(object, field_index);
if (old_value == new_value) {
// This store is fully redundant.
return Replace(effect);
}
// Kill all potentially aliasing fields and record the new value.
state = state->KillField(object, field_index, access.name, zone());
state =
state->AddField(object, field_index, new_value, access.name, zone());
} else {
// Unsupported StoreField operator.
state = state->KillFields(object, access.name, zone());
}
}
return UpdateState(node, state);
}
Reduction LoadElimination::ReduceLoadElement(Node* node) {
Node* const object = NodeProperties::GetValueInput(node, 0);
Node* const index = NodeProperties::GetValueInput(node, 1);
Node* const effect = NodeProperties::GetEffectInput(node);
AbstractState const* state = node_states_.Get(effect);
if (state == nullptr) return NoChange();
// Only handle loads that do not require truncations.
ElementAccess const& access = ElementAccessOf(node->op());
switch (access.machine_type.representation()) {
case MachineRepresentation::kNone:
case MachineRepresentation::kBit:
UNREACHABLE();
break;
case MachineRepresentation::kWord8:
case MachineRepresentation::kWord16:
case MachineRepresentation::kWord32:
case MachineRepresentation::kWord64:
case MachineRepresentation::kFloat32:
// TODO(turbofan): Add support for doing the truncations.
break;
case MachineRepresentation::kFloat64:
case MachineRepresentation::kSimd128:
case MachineRepresentation::kTaggedSigned:
case MachineRepresentation::kTaggedPointer:
case MachineRepresentation::kTagged:
if (Node* replacement = state->LookupElement(
object, index, access.machine_type.representation())) {
// Make sure we don't resurrect dead {replacement} nodes.
// Skip lowering if the type of the {replacement} node is not a subtype
// of the original {node}'s type.
// TODO(tebbi): We should insert a {TypeGuard} for the intersection of
// these two types here once we properly handle {Type::None} everywhere.
if (!replacement->IsDead() && NodeProperties::GetType(replacement)
->Is(NodeProperties::GetType(node))) {
ReplaceWithValue(node, replacement, effect);
return Replace(replacement);
}
}
state = state->AddElement(object, index, node,
access.machine_type.representation(), zone());
return UpdateState(node, state);
}
return NoChange();
}
Reduction LoadElimination::ReduceStoreElement(Node* node) {
ElementAccess const& access = ElementAccessOf(node->op());
Node* const object = NodeProperties::GetValueInput(node, 0);
Node* const index = NodeProperties::GetValueInput(node, 1);
Node* const new_value = NodeProperties::GetValueInput(node, 2);
Node* const effect = NodeProperties::GetEffectInput(node);
AbstractState const* state = node_states_.Get(effect);
if (state == nullptr) return NoChange();
Node* const old_value =
state->LookupElement(object, index, access.machine_type.representation());
if (old_value == new_value) {
// This store is fully redundant.
return Replace(effect);
}
// Kill all potentially aliasing elements.
state = state->KillElement(object, index, zone());
// Only record the new value if the store doesn't have an implicit truncation.
switch (access.machine_type.representation()) {
case MachineRepresentation::kNone:
case MachineRepresentation::kBit:
UNREACHABLE();
break;
case MachineRepresentation::kWord8:
case MachineRepresentation::kWord16:
case MachineRepresentation::kWord32:
case MachineRepresentation::kWord64:
case MachineRepresentation::kFloat32:
// TODO(turbofan): Add support for doing the truncations.
break;
case MachineRepresentation::kFloat64:
case MachineRepresentation::kSimd128:
case MachineRepresentation::kTaggedSigned:
case MachineRepresentation::kTaggedPointer:
case MachineRepresentation::kTagged:
state = state->AddElement(object, index, new_value,
access.machine_type.representation(), zone());
break;
}
return UpdateState(node, state);
}
Reduction LoadElimination::ReduceStoreTypedElement(Node* node) {
Node* const effect = NodeProperties::GetEffectInput(node);
AbstractState const* state = node_states_.Get(effect);
if (state == nullptr) return NoChange();
return UpdateState(node, state);
}
LoadElimination::AbstractState const* LoadElimination::UpdateStateForPhi(
AbstractState const* state, Node* effect_phi, Node* phi) {
int predecessor_count = phi->InputCount() - 1;
// TODO(jarin) Consider doing a union here. At the moment, we just keep this
// consistent with AbstractState::Merge.
// Check if all the inputs have the same maps.
AbstractState const* input_state =
node_states_.Get(NodeProperties::GetEffectInput(effect_phi, 0));
ZoneHandleSet<Map> object_maps;
if (!input_state->LookupMaps(phi->InputAt(0), &object_maps)) return state;
for (int i = 1; i < predecessor_count; i++) {
input_state =
node_states_.Get(NodeProperties::GetEffectInput(effect_phi, i));
ZoneHandleSet<Map> input_maps;
if (!input_state->LookupMaps(phi->InputAt(i), &input_maps)) return state;
if (input_maps != object_maps) return state;
}
return state->SetMaps(phi, object_maps, zone());
}
Reduction LoadElimination::ReduceEffectPhi(Node* node) {
Node* const effect0 = NodeProperties::GetEffectInput(node, 0);
Node* const control = NodeProperties::GetControlInput(node);
AbstractState const* state0 = node_states_.Get(effect0);
if (state0 == nullptr) return NoChange();
if (control->opcode() == IrOpcode::kLoop) {
// Here we rely on having only reducible loops:
// The loop entry edge always dominates the header, so we can just take
// the state from the first input, and compute the loop state based on it.
AbstractState const* state = ComputeLoopState(node, state0);
return UpdateState(node, state);
}
DCHECK_EQ(IrOpcode::kMerge, control->opcode());
// Shortcut for the case when we do not know anything about some input.
int const input_count = node->op()->EffectInputCount();
for (int i = 1; i < input_count; ++i) {
Node* const effect = NodeProperties::GetEffectInput(node, i);
if (node_states_.Get(effect) == nullptr) return NoChange();
}
// Make a copy of the first input's state and merge with the state
// from other inputs.
AbstractState* state = new (zone()) AbstractState(*state0);
for (int i = 1; i < input_count; ++i) {
Node* const input = NodeProperties::GetEffectInput(node, i);
state->Merge(node_states_.Get(input), zone());
}
// For each phi, try to compute the new state for the phi from
// the inputs.
AbstractState const* state_with_phis = state;
for (Node* use : control->uses()) {
if (use->opcode() == IrOpcode::kPhi) {
state_with_phis = UpdateStateForPhi(state_with_phis, node, use);
}
}
return UpdateState(node, state_with_phis);
}
Reduction LoadElimination::ReduceStart(Node* node) {
return UpdateState(node, empty_state());
}
Reduction LoadElimination::ReduceOtherNode(Node* node) {
if (node->op()->EffectInputCount() == 1) {
if (node->op()->EffectOutputCount() == 1) {
Node* const effect = NodeProperties::GetEffectInput(node);
AbstractState const* state = node_states_.Get(effect);
// If we do not know anything about the predecessor, do not propagate
// just yet because we will have to recompute anyway once we compute
// the predecessor.
if (state == nullptr) return NoChange();
// Check if this {node} has some uncontrolled side effects.
if (!node->op()->HasProperty(Operator::kNoWrite)) {
state = empty_state();
}
return UpdateState(node, state);
} else {
// Effect terminators should be handled specially.
return NoChange();
}
}
DCHECK_EQ(0, node->op()->EffectInputCount());
DCHECK_EQ(0, node->op()->EffectOutputCount());
return NoChange();
}
Reduction LoadElimination::UpdateState(Node* node, AbstractState const* state) {
AbstractState const* original = node_states_.Get(node);
// Only signal that the {node} has Changed, if the information about {state}
// has changed wrt. the {original}.
if (state != original) {
if (original == nullptr || !state->Equals(original)) {
node_states_.Set(node, state);
return Changed(node);
}
}
return NoChange();
}
LoadElimination::AbstractState const* LoadElimination::ComputeLoopState(
Node* node, AbstractState const* state) const {
Node* const control = NodeProperties::GetControlInput(node);
struct TransitionElementsKindInfo {
ElementsTransition transition;
Node* object;
};
ZoneVector<TransitionElementsKindInfo> element_transitions_(zone());
ZoneQueue<Node*> queue(zone());
ZoneSet<Node*> visited(zone());
visited.insert(node);
for (int i = 1; i < control->InputCount(); ++i) {
queue.push(node->InputAt(i));
}
while (!queue.empty()) {
Node* const current = queue.front();
queue.pop();
if (visited.find(current) == visited.end()) {
visited.insert(current);
if (!current->op()->HasProperty(Operator::kNoWrite)) {
switch (current->opcode()) {
case IrOpcode::kEnsureWritableFastElements: {
Node* const object = NodeProperties::GetValueInput(current, 0);
state = state->KillField(object,
FieldIndexOf(JSObject::kElementsOffset),
MaybeHandle<Name>(), zone());
break;
}
case IrOpcode::kMaybeGrowFastElements: {
Node* const object = NodeProperties::GetValueInput(current, 0);
state = state->KillField(object,
FieldIndexOf(JSObject::kElementsOffset),
MaybeHandle<Name>(), zone());
break;
}
case IrOpcode::kTransitionElementsKind: {
ElementsTransition transition = ElementsTransitionOf(current->op());
Node* const object = NodeProperties::GetValueInput(current, 0);
ZoneHandleSet<Map> object_maps;
if (!state->LookupMaps(object, &object_maps) ||
!ZoneHandleSet<Map>(transition.target())
.contains(object_maps)) {
element_transitions_.push_back({transition, object});
}
break;
}
case IrOpcode::kTransitionAndStoreElement: {
Node* const object = NodeProperties::GetValueInput(current, 0);
// Invalidate what we know about the {object}s map.
state = state->KillMaps(object, zone());
// Kill the elements as well.
state = state->KillField(object,
FieldIndexOf(JSObject::kElementsOffset),
MaybeHandle<Name>(), zone());
break;
}
case IrOpcode::kStoreField: {
FieldAccess const& access = FieldAccessOf(current->op());
Node* const object = NodeProperties::GetValueInput(current, 0);
if (access.offset == HeapObject::kMapOffset) {
// Invalidate what we know about the {object}s map.
state = state->KillMaps(object, zone());
} else {
int field_index = FieldIndexOf(access);
if (field_index < 0) {
state = state->KillFields(object, access.name, zone());
} else {
state =
state->KillField(object, field_index, access.name, zone());
}
}
break;
}
case IrOpcode::kStoreElement: {
Node* const object = NodeProperties::GetValueInput(current, 0);
Node* const index = NodeProperties::GetValueInput(current, 1);
state = state->KillElement(object, index, zone());
break;
}
case IrOpcode::kStoreTypedElement: {
// Doesn't affect anything we track with the state currently.
break;
}
default:
return empty_state();
}
}
for (int i = 0; i < current->op()->EffectInputCount(); ++i) {
queue.push(NodeProperties::GetEffectInput(current, i));
}
}
}
// Finally, we apply the element transitions. For each transition, we will try
// to only invalidate information about nodes that can have the transition's
// source map. The trouble is that an object can be transitioned by some other
// transition to the source map. In that case, the other transition will
// invalidate the information, so we are mostly fine.
//
// The only bad case is
//
// mapA ---fast---> mapB ---slow---> mapC
//
// If we process the slow transition first on an object that has mapA, we will
// ignore the transition because the object does not have its source map
// (mapB). When we later process the fast transition, we invalidate the
// object's map, but we keep the information about the object's elements. This
// is wrong because the elements will be overwritten by the slow transition.
//
// Note that the slow-slow case is fine because either of the slow transition
// will invalidate the elements field, so the processing order does not
// matter.
//
// To handle the bad case properly, we first kill the maps using all
// transitions. We kill the the fields later when all the transitions are
// already reflected in the map information.
for (const TransitionElementsKindInfo& t : element_transitions_) {
AliasStateInfo alias_info(state, t.object, t.transition.source());
state = state->KillMaps(alias_info, zone());
}
for (const TransitionElementsKindInfo& t : element_transitions_) {
switch (t.transition.mode()) {
case ElementsTransition::kFastTransition:
break;
case ElementsTransition::kSlowTransition: {
AliasStateInfo alias_info(state, t.object, t.transition.source());
state = state->KillField(alias_info,
FieldIndexOf(JSObject::kElementsOffset),
MaybeHandle<Name>(), zone());
break;
}
}
}
return state;
}
// static
int LoadElimination::FieldIndexOf(int offset) {
DCHECK_EQ(0, offset % kPointerSize);
int field_index = offset / kPointerSize;
if (field_index >= static_cast<int>(kMaxTrackedFields)) return -1;
DCHECK_LT(0, field_index);
return field_index - 1;
}
// static
int LoadElimination::FieldIndexOf(FieldAccess const& access) {
MachineRepresentation rep = access.machine_type.representation();
switch (rep) {
case MachineRepresentation::kNone:
case MachineRepresentation::kBit:
case MachineRepresentation::kSimd128:
UNREACHABLE();
break;
case MachineRepresentation::kWord32:
case MachineRepresentation::kWord64:
if (rep != MachineType::PointerRepresentation()) {
return -1; // We currently only track pointer size fields.
}
break;
case MachineRepresentation::kWord8:
case MachineRepresentation::kWord16:
case MachineRepresentation::kFloat32:
return -1; // Currently untracked.
case MachineRepresentation::kFloat64:
if (kDoubleSize != kPointerSize) {
return -1; // We currently only track pointer size fields.
}
// Fall through.
case MachineRepresentation::kTaggedSigned:
case MachineRepresentation::kTaggedPointer:
case MachineRepresentation::kTagged:
// TODO(bmeurer): Check that we never do overlapping load/stores of
// individual parts of Float64 values.
break;
}
if (access.base_is_tagged != kTaggedBase) {
return -1; // We currently only track tagged objects.
}
return FieldIndexOf(access.offset);
}
CommonOperatorBuilder* LoadElimination::common() const {
return jsgraph()->common();
}
Graph* LoadElimination::graph() const { return jsgraph()->graph(); }
Factory* LoadElimination::factory() const { return jsgraph()->factory(); }
} // namespace compiler
} // namespace internal
} // namespace v8