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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 "src/compiler/escape-analysis.h"
#include <limits>
#include "src/base/flags.h"
#include "src/bootstrapper.h"
#include "src/compilation-dependencies.h"
#include "src/compiler/common-operator.h"
#include "src/compiler/graph-reducer.h"
#include "src/compiler/js-operator.h"
#include "src/compiler/node.h"
#include "src/compiler/node-matchers.h"
#include "src/compiler/node-properties.h"
#include "src/compiler/operator-properties.h"
#include "src/compiler/simplified-operator.h"
#include "src/objects-inl.h"
#include "src/type-cache.h"
namespace v8 {
namespace internal {
namespace compiler {
const EscapeAnalysis::Alias EscapeAnalysis::kNotReachable =
std::numeric_limits<Alias>::max();
const EscapeAnalysis::Alias EscapeAnalysis::kUntrackable =
std::numeric_limits<Alias>::max() - 1;
class VirtualObject : public ZoneObject {
public:
enum Status { kUntracked = 0, kTracked = 1 };
VirtualObject(NodeId id, Zone* zone)
: id_(id),
status_(kUntracked),
fields_(zone),
phi_(zone),
object_state_(nullptr) {}
VirtualObject(const VirtualObject& other)
: id_(other.id_),
status_(other.status_),
fields_(other.fields_),
phi_(other.phi_),
object_state_(other.object_state_) {}
VirtualObject(NodeId id, Zone* zone, size_t field_number)
: id_(id),
status_(kTracked),
fields_(zone),
phi_(zone),
object_state_(nullptr) {
fields_.resize(field_number);
phi_.resize(field_number, false);
}
Node* GetField(size_t offset) {
if (offset < fields_.size()) {
return fields_[offset];
}
return nullptr;
}
bool IsCreatedPhi(size_t offset) {
if (offset < phi_.size()) {
return phi_[offset];
}
return false;
}
bool SetField(size_t offset, Node* node, bool created_phi = false) {
bool changed = fields_[offset] != node || phi_[offset] != created_phi;
fields_[offset] = node;
phi_[offset] = created_phi;
if (changed && FLAG_trace_turbo_escape && node) {
PrintF("Setting field %zu of #%d to #%d (%s)\n", offset, id(), node->id(),
node->op()->mnemonic());
}
return changed;
}
bool IsVirtual() const { return status_ == kTracked; }
bool IsTracked() const { return status_ != kUntracked; }
Node** fields_array() { return &fields_.front(); }
size_t field_count() { return fields_.size(); }
bool ResizeFields(size_t field_count) {
if (field_count != fields_.size()) {
fields_.resize(field_count);
phi_.resize(field_count);
return true;
}
return false;
}
bool ClearAllFields() {
bool changed = false;
for (size_t i = 0; i < fields_.size(); ++i) {
if (fields_[i] != nullptr) {
fields_[i] = nullptr;
changed = true;
}
phi_[i] = false;
}
return changed;
}
bool UpdateFrom(const VirtualObject& other);
void SetObjectState(Node* node) { object_state_ = node; }
Node* GetObjectState() const { return object_state_; }
NodeId id() const { return id_; }
void id(NodeId id) { id_ = id; }
private:
NodeId id_;
Status status_;
ZoneVector<Node*> fields_;
ZoneVector<bool> phi_;
Node* object_state_;
};
bool VirtualObject::UpdateFrom(const VirtualObject& other) {
bool changed = status_ != other.status_;
status_ = other.status_;
if (fields_.size() != other.fields_.size()) {
fields_ = other.fields_;
return true;
}
for (size_t i = 0; i < fields_.size(); ++i) {
if (fields_[i] != other.fields_[i]) {
changed = true;
fields_[i] = other.fields_[i];
}
}
return changed;
}
class VirtualState : public ZoneObject {
public:
VirtualState(Zone* zone, size_t size);
VirtualState(const VirtualState& states);
VirtualObject* VirtualObjectFromAlias(size_t alias);
VirtualObject* GetOrCreateTrackedVirtualObject(EscapeAnalysis::Alias alias,
NodeId id, Zone* zone);
void SetVirtualObject(EscapeAnalysis::Alias alias, VirtualObject* state);
void LastChangedAt(Node* node) { last_changed_ = node; }
Node* GetLastChanged() { return last_changed_; }
bool UpdateFrom(VirtualState* state, Zone* zone);
bool MergeFrom(MergeCache* cache, Zone* zone, Graph* graph,
CommonOperatorBuilder* common, Node* control);
size_t size() const { return info_.size(); }
private:
ZoneVector<VirtualObject*> info_;
Node* last_changed_;
};
class MergeCache : public ZoneObject {
public:
explicit MergeCache(Zone* zone)
: states_(zone), objects_(zone), fields_(zone) {
states_.reserve(4);
objects_.reserve(4);
fields_.reserve(4);
}
ZoneVector<VirtualState*>& states() { return states_; }
ZoneVector<VirtualObject*>& objects() { return objects_; }
ZoneVector<Node*>& fields() { return fields_; }
void Clear() {
states_.clear();
objects_.clear();
fields_.clear();
}
size_t LoadVirtualObjectsFromStatesFor(EscapeAnalysis::Alias alias);
void LoadVirtualObjectsForFieldsFrom(
VirtualState* state, const ZoneVector<EscapeAnalysis::Alias>& aliases);
Node* GetFields(size_t pos);
private:
ZoneVector<VirtualState*> states_;
ZoneVector<VirtualObject*> objects_;
ZoneVector<Node*> fields_;
};
size_t MergeCache::LoadVirtualObjectsFromStatesFor(
EscapeAnalysis::Alias alias) {
objects_.clear();
DCHECK_GT(states_.size(), 0u);
size_t min = std::numeric_limits<size_t>::max();
for (VirtualState* state : states_) {
if (VirtualObject* obj = state->VirtualObjectFromAlias(alias)) {
objects_.push_back(obj);
min = std::min(obj->field_count(), min);
}
}
return min;
}
void MergeCache::LoadVirtualObjectsForFieldsFrom(
VirtualState* state, const ZoneVector<EscapeAnalysis::Alias>& aliases) {
objects_.clear();
size_t max_alias = state->size();
for (Node* field : fields_) {
EscapeAnalysis::Alias alias = aliases[field->id()];
if (alias >= max_alias) continue;
if (VirtualObject* obj = state->VirtualObjectFromAlias(alias)) {
objects_.push_back(obj);
}
}
}
Node* MergeCache::GetFields(size_t pos) {
fields_.clear();
Node* rep = objects_.front()->GetField(pos);
for (VirtualObject* obj : objects_) {
Node* field = obj->GetField(pos);
if (field) {
fields_.push_back(field);
}
if (field != rep) {
rep = nullptr;
}
}
return rep;
}
VirtualState::VirtualState(Zone* zone, size_t size)
: info_(size, nullptr, zone), last_changed_(nullptr) {}
VirtualState::VirtualState(const VirtualState& state)
: info_(state.info_.size(), nullptr, state.info_.get_allocator().zone()),
last_changed_(state.last_changed_) {
for (size_t i = 0; i < state.info_.size(); ++i) {
if (state.info_[i]) {
info_[i] =
new (info_.get_allocator().zone()) VirtualObject(*state.info_[i]);
}
}
}
VirtualObject* VirtualState::VirtualObjectFromAlias(size_t alias) {
return info_[alias];
}
VirtualObject* VirtualState::GetOrCreateTrackedVirtualObject(
EscapeAnalysis::Alias alias, NodeId id, Zone* zone) {
if (VirtualObject* obj = VirtualObjectFromAlias(alias)) {
return obj;
}
VirtualObject* obj = new (zone) VirtualObject(id, zone, 0);
SetVirtualObject(alias, obj);
return obj;
}
void VirtualState::SetVirtualObject(EscapeAnalysis::Alias alias,
VirtualObject* obj) {
info_[alias] = obj;
}
bool VirtualState::UpdateFrom(VirtualState* from, Zone* zone) {
bool changed = false;
for (EscapeAnalysis::Alias alias = 0; alias < size(); ++alias) {
VirtualObject* ls = VirtualObjectFromAlias(alias);
VirtualObject* rs = from->VirtualObjectFromAlias(alias);
if (rs == nullptr) {
continue;
}
if (ls == nullptr) {
ls = new (zone) VirtualObject(*rs);
SetVirtualObject(alias, ls);
changed = true;
continue;
}
if (FLAG_trace_turbo_escape) {
PrintF(" Updating fields of @%d\n", alias);
}
changed = ls->UpdateFrom(*rs) || changed;
}
return false;
}
namespace {
bool IsEquivalentPhi(Node* node1, Node* node2) {
if (node1 == node2) return true;
if (node1->opcode() != IrOpcode::kPhi || node2->opcode() != IrOpcode::kPhi ||
node1->op()->ValueInputCount() != node2->op()->ValueInputCount()) {
return false;
}
for (int i = 0; i < node1->op()->ValueInputCount(); ++i) {
Node* input1 = NodeProperties::GetValueInput(node1, i);
Node* input2 = NodeProperties::GetValueInput(node2, i);
if (!IsEquivalentPhi(input1, input2)) {
return false;
}
}
return true;
}
bool IsEquivalentPhi(Node* phi, ZoneVector<Node*>& inputs) {
if (phi->opcode() != IrOpcode::kPhi) return false;
if (phi->op()->ValueInputCount() != inputs.size()) {
return false;
}
for (size_t i = 0; i < inputs.size(); ++i) {
Node* input = NodeProperties::GetValueInput(phi, static_cast<int>(i));
if (!IsEquivalentPhi(input, inputs[i])) {
return false;
}
}
return true;
}
} // namespace
Node* EscapeAnalysis::GetReplacementIfSame(ZoneVector<VirtualObject*>& objs) {
Node* rep = GetReplacement(objs.front()->id());
for (VirtualObject* obj : objs) {
if (GetReplacement(obj->id()) != rep) {
return nullptr;
}
}
return rep;
}
bool VirtualState::MergeFrom(MergeCache* cache, Zone* zone, Graph* graph,
CommonOperatorBuilder* common, Node* control) {
DCHECK_GT(cache->states().size(), 0u);
bool changed = false;
for (EscapeAnalysis::Alias alias = 0; alias < size(); ++alias) {
size_t fields = cache->LoadVirtualObjectsFromStatesFor(alias);
if (cache->objects().size() == cache->states().size()) {
if (FLAG_trace_turbo_escape) {
PrintF(" Merging virtual objects of @%d\n", alias);
}
VirtualObject* mergeObject = GetOrCreateTrackedVirtualObject(
alias, cache->objects().front()->id(), zone);
changed = mergeObject->ResizeFields(fields) || changed;
for (size_t i = 0; i < fields; ++i) {
if (Node* field = cache->GetFields(i)) {
changed = mergeObject->SetField(i, field) || changed;
if (FLAG_trace_turbo_escape) {
PrintF(" Field %zu agree on rep #%d\n", i, field->id());
}
} else {
int value_input_count = static_cast<int>(cache->fields().size());
if (cache->fields().size() == cache->objects().size()) {
Node* rep = mergeObject->GetField(i);
if (!rep || !mergeObject->IsCreatedPhi(i)) {
cache->fields().push_back(control);
Node* phi = graph->NewNode(
common->Phi(MachineRepresentation::kTagged,
value_input_count),
value_input_count + 1, &cache->fields().front());
mergeObject->SetField(i, phi, true);
if (FLAG_trace_turbo_escape) {
PrintF(" Creating Phi #%d as merge of", phi->id());
for (int i = 0; i < value_input_count; i++) {
PrintF(" #%d (%s)", cache->fields()[i]->id(),
cache->fields()[i]->op()->mnemonic());
}
PrintF("\n");
}
changed = true;
} else {
DCHECK(rep->opcode() == IrOpcode::kPhi);
for (int n = 0; n < value_input_count; ++n) {
if (n < rep->op()->ValueInputCount()) {
Node* old = NodeProperties::GetValueInput(rep, n);
if (old != cache->fields()[n]) {
changed = true;
NodeProperties::ReplaceValueInput(rep, cache->fields()[n],
n);
}
} else {
changed = true;
rep->InsertInput(graph->zone(), n, cache->fields()[n]);
}
}
if (rep->op()->ValueInputCount() != value_input_count) {
if (FLAG_trace_turbo_escape) {
PrintF(" Widening Phi #%d of arity %d to %d", rep->id(),
rep->op()->ValueInputCount(), value_input_count);
}
NodeProperties::ChangeOp(
rep, common->Phi(MachineRepresentation::kTagged,
value_input_count));
}
}
} else {
changed = mergeObject->SetField(i, nullptr) || changed;
}
}
}
} else {
SetVirtualObject(alias, nullptr);
}
}
return changed;
}
EscapeStatusAnalysis::EscapeStatusAnalysis(EscapeAnalysis* object_analysis,
Graph* graph, Zone* zone)
: object_analysis_(object_analysis),
graph_(graph),
zone_(zone),
status_(graph->NodeCount(), kUnknown, zone),
queue_(zone) {}
EscapeStatusAnalysis::~EscapeStatusAnalysis() {}
bool EscapeStatusAnalysis::HasEntry(Node* node) {
return status_[node->id()] & (kTracked | kEscaped);
}
bool EscapeStatusAnalysis::IsVirtual(Node* node) {
return (status_[node->id()] & kTracked) && !(status_[node->id()] & kEscaped);
}
bool EscapeStatusAnalysis::IsEscaped(Node* node) {
return status_[node->id()] & kEscaped;
}
bool EscapeStatusAnalysis::IsAllocation(Node* node) {
return node->opcode() == IrOpcode::kAllocate ||
node->opcode() == IrOpcode::kFinishRegion;
}
bool EscapeStatusAnalysis::SetEscaped(Node* node) {
bool changed = !(status_[node->id()] & kEscaped);
status_[node->id()] |= kEscaped | kTracked;
return changed;
}
void EscapeStatusAnalysis::Resize() {
status_.resize(graph()->NodeCount(), kUnknown);
}
size_t EscapeStatusAnalysis::size() { return status_.size(); }
void EscapeStatusAnalysis::Run() {
Resize();
queue_.push_back(graph()->end());
status_[graph()->end()->id()] |= kOnStack;
while (!queue_.empty()) {
Node* node = queue_.front();
queue_.pop_front();
status_[node->id()] &= ~kOnStack;
Process(node);
status_[node->id()] |= kVisited;
for (Edge edge : node->input_edges()) {
Node* input = edge.to();
if (!(status_[input->id()] & (kVisited | kOnStack))) {
queue_.push_back(input);
status_[input->id()] |= kOnStack;
}
}
}
}
void EscapeStatusAnalysis::RevisitInputs(Node* node) {
for (Edge edge : node->input_edges()) {
Node* input = edge.to();
if (!(status_[input->id()] & kOnStack)) {
queue_.push_back(input);
status_[input->id()] |= kOnStack;
}
}
}
void EscapeStatusAnalysis::RevisitUses(Node* node) {
for (Edge edge : node->use_edges()) {
Node* use = edge.from();
if (!(status_[use->id()] & kOnStack)) {
queue_.push_back(use);
status_[use->id()] |= kOnStack;
}
}
}
void EscapeStatusAnalysis::Process(Node* node) {
switch (node->opcode()) {
case IrOpcode::kAllocate:
ProcessAllocate(node);
break;
case IrOpcode::kFinishRegion:
ProcessFinishRegion(node);
break;
case IrOpcode::kStoreField:
ProcessStoreField(node);
break;
case IrOpcode::kStoreElement:
ProcessStoreElement(node);
break;
case IrOpcode::kLoadField:
case IrOpcode::kLoadElement: {
if (Node* rep = object_analysis_->GetReplacement(node)) {
if (IsAllocation(rep) && CheckUsesForEscape(node, rep)) {
RevisitInputs(rep);
RevisitUses(rep);
}
}
break;
}
case IrOpcode::kPhi:
if (!HasEntry(node)) {
status_[node->id()] |= kTracked;
if (!IsAllocationPhi(node)) {
SetEscaped(node);
RevisitUses(node);
}
}
CheckUsesForEscape(node);
default:
break;
}
}
bool EscapeStatusAnalysis::IsAllocationPhi(Node* node) {
for (Edge edge : node->input_edges()) {
Node* input = edge.to();
if (input->opcode() == IrOpcode::kPhi && !IsEscaped(input)) continue;
if (IsAllocation(input)) continue;
return false;
}
return true;
}
void EscapeStatusAnalysis::ProcessStoreField(Node* node) {
DCHECK_EQ(node->opcode(), IrOpcode::kStoreField);
Node* to = NodeProperties::GetValueInput(node, 0);
Node* val = NodeProperties::GetValueInput(node, 1);
if ((IsEscaped(to) || !IsAllocation(to)) && SetEscaped(val)) {
RevisitUses(val);
RevisitInputs(val);
if (FLAG_trace_turbo_escape) {
PrintF("Setting #%d (%s) to escaped because of store to field of #%d\n",
val->id(), val->op()->mnemonic(), to->id());
}
}
}
void EscapeStatusAnalysis::ProcessStoreElement(Node* node) {
DCHECK_EQ(node->opcode(), IrOpcode::kStoreElement);
Node* to = NodeProperties::GetValueInput(node, 0);
Node* val = NodeProperties::GetValueInput(node, 2);
if ((IsEscaped(to) || !IsAllocation(to)) && SetEscaped(val)) {
RevisitUses(val);
RevisitInputs(val);
if (FLAG_trace_turbo_escape) {
PrintF("Setting #%d (%s) to escaped because of store to field of #%d\n",
val->id(), val->op()->mnemonic(), to->id());
}
}
}
void EscapeStatusAnalysis::ProcessAllocate(Node* node) {
DCHECK_EQ(node->opcode(), IrOpcode::kAllocate);
if (!HasEntry(node)) {
status_[node->id()] |= kTracked;
if (FLAG_trace_turbo_escape) {
PrintF("Created status entry for node #%d (%s)\n", node->id(),
node->op()->mnemonic());
}
NumberMatcher size(node->InputAt(0));
DCHECK(node->InputAt(0)->opcode() != IrOpcode::kInt32Constant &&
node->InputAt(0)->opcode() != IrOpcode::kInt64Constant &&
node->InputAt(0)->opcode() != IrOpcode::kFloat32Constant &&
node->InputAt(0)->opcode() != IrOpcode::kFloat64Constant);
if (!size.HasValue() && SetEscaped(node)) {
RevisitUses(node);
if (FLAG_trace_turbo_escape) {
PrintF("Setting #%d to escaped because of non-const alloc\n",
node->id());
}
// This node is known to escape, uses do not have to be checked.
return;
}
}
if (CheckUsesForEscape(node, true)) {
RevisitUses(node);
}
}
bool EscapeStatusAnalysis::CheckUsesForEscape(Node* uses, Node* rep,
bool phi_escaping) {
for (Edge edge : uses->use_edges()) {
Node* use = edge.from();
if (edge.index() >= use->op()->ValueInputCount() +
OperatorProperties::GetContextInputCount(use->op()))
continue;
switch (use->opcode()) {
case IrOpcode::kPhi:
if (phi_escaping && SetEscaped(rep)) {
if (FLAG_trace_turbo_escape) {
PrintF(
"Setting #%d (%s) to escaped because of use by phi node "
"#%d (%s)\n",
rep->id(), rep->op()->mnemonic(), use->id(),
use->op()->mnemonic());
}
return true;
}
// Fallthrough.
case IrOpcode::kStoreField:
case IrOpcode::kLoadField:
case IrOpcode::kStoreElement:
case IrOpcode::kLoadElement:
case IrOpcode::kFrameState:
case IrOpcode::kStateValues:
case IrOpcode::kReferenceEqual:
case IrOpcode::kFinishRegion:
if (IsEscaped(use) && SetEscaped(rep)) {
if (FLAG_trace_turbo_escape) {
PrintF(
"Setting #%d (%s) to escaped because of use by escaping node "
"#%d (%s)\n",
rep->id(), rep->op()->mnemonic(), use->id(),
use->op()->mnemonic());
}
return true;
}
break;
case IrOpcode::kObjectIsSmi:
if (!IsAllocation(rep) && SetEscaped(rep)) {
PrintF("Setting #%d (%s) to escaped because of use by #%d (%s)\n",
rep->id(), rep->op()->mnemonic(), use->id(),
use->op()->mnemonic());
return true;
}
break;
default:
if (use->op()->EffectInputCount() == 0 &&
uses->op()->EffectInputCount() > 0) {
PrintF("Encountered unaccounted use by #%d (%s)\n", use->id(),
use->op()->mnemonic());
UNREACHABLE();
}
if (SetEscaped(rep)) {
if (FLAG_trace_turbo_escape) {
PrintF("Setting #%d (%s) to escaped because of use by #%d (%s)\n",
rep->id(), rep->op()->mnemonic(), use->id(),
use->op()->mnemonic());
}
return true;
}
}
}
return false;
}
void EscapeStatusAnalysis::ProcessFinishRegion(Node* node) {
DCHECK_EQ(node->opcode(), IrOpcode::kFinishRegion);
if (!HasEntry(node)) {
status_[node->id()] |= kTracked;
RevisitUses(node);
}
if (CheckUsesForEscape(node, true)) {
RevisitInputs(node);
}
}
void EscapeStatusAnalysis::DebugPrint() {
for (NodeId id = 0; id < status_.size(); id++) {
if (status_[id] & kTracked) {
PrintF("Node #%d is %s\n", id,
(status_[id] & kEscaped) ? "escaping" : "virtual");
}
}
}
EscapeAnalysis::EscapeAnalysis(Graph* graph, CommonOperatorBuilder* common,
Zone* zone)
: graph_(graph),
common_(common),
zone_(zone),
virtual_states_(zone),
replacements_(zone),
escape_status_(this, graph, zone),
cache_(new (zone) MergeCache(zone)),
aliases_(zone),
next_free_alias_(0) {}
EscapeAnalysis::~EscapeAnalysis() {}
void EscapeAnalysis::Run() {
replacements_.resize(graph()->NodeCount());
AssignAliases();
RunObjectAnalysis();
escape_status_.Run();
}
void EscapeAnalysis::AssignAliases() {
ZoneVector<Node*> stack(zone());
stack.push_back(graph()->end());
CHECK_LT(graph()->NodeCount(), kUntrackable);
aliases_.resize(graph()->NodeCount(), kNotReachable);
aliases_[graph()->end()->id()] = kUntrackable;
while (!stack.empty()) {
Node* node = stack.back();
stack.pop_back();
switch (node->opcode()) {
case IrOpcode::kAllocate:
if (aliases_[node->id()] >= kUntrackable) {
aliases_[node->id()] = NextAlias();
}
break;
case IrOpcode::kFinishRegion: {
Node* allocate = NodeProperties::GetValueInput(node, 0);
if (allocate->opcode() == IrOpcode::kAllocate) {
if (aliases_[allocate->id()] >= kUntrackable) {
if (aliases_[allocate->id()] == kNotReachable) {
stack.push_back(allocate);
}
aliases_[allocate->id()] = NextAlias();
}
aliases_[node->id()] = aliases_[allocate->id()];
} else {
aliases_[node->id()] = NextAlias();
}
break;
}
default:
DCHECK_EQ(aliases_[node->id()], kUntrackable);
break;
}
for (Edge edge : node->input_edges()) {
Node* input = edge.to();
if (aliases_[input->id()] == kNotReachable) {
stack.push_back(input);
aliases_[input->id()] = kUntrackable;
}
}
}
if (FLAG_trace_turbo_escape) {
PrintF("Discovered trackable nodes");
for (EscapeAnalysis::Alias id = 0; id < graph()->NodeCount(); ++id) {
if (aliases_[id] < kUntrackable) {
if (FLAG_trace_turbo_escape) {
PrintF(" #%u", id);
}
}
}
PrintF("\n");
}
}
void EscapeAnalysis::RunObjectAnalysis() {
virtual_states_.resize(graph()->NodeCount());
ZoneVector<Node*> stack(zone());
stack.push_back(graph()->start());
while (!stack.empty()) {
Node* node = stack.back();
stack.pop_back();
if (aliases_[node->id()] != kNotReachable && Process(node)) {
for (Edge edge : node->use_edges()) {
if (NodeProperties::IsEffectEdge(edge)) {
Node* use = edge.from();
if ((use->opcode() != IrOpcode::kLoadField &&
use->opcode() != IrOpcode::kLoadElement) ||
!IsDanglingEffectNode(use)) {
stack.push_back(use);
}
}
}
// First process loads: dangling loads are a problem otherwise.
for (Edge edge : node->use_edges()) {
if (NodeProperties::IsEffectEdge(edge)) {
Node* use = edge.from();
if ((use->opcode() == IrOpcode::kLoadField ||
use->opcode() == IrOpcode::kLoadElement) &&
IsDanglingEffectNode(use)) {
stack.push_back(use);
}
}
}
}
}
if (FLAG_trace_turbo_escape) {
DebugPrint();
}
}
bool EscapeAnalysis::IsDanglingEffectNode(Node* node) {
if (node->op()->EffectInputCount() == 0) return false;
if (node->op()->EffectOutputCount() == 0) return false;
if (node->op()->EffectInputCount() == 1 &&
NodeProperties::GetEffectInput(node)->opcode() == IrOpcode::kStart) {
// The start node is used as sentinel for nodes that are in general
// effectful, but of which an analysis has determined that they do not
// produce effects in this instance. We don't consider these nodes dangling.
return false;
}
for (Edge edge : node->use_edges()) {
if (NodeProperties::IsEffectEdge(edge)) {
return false;
}
}
return true;
}
bool EscapeAnalysis::Process(Node* node) {
switch (node->opcode()) {
case IrOpcode::kAllocate:
ProcessAllocation(node);
break;
case IrOpcode::kBeginRegion:
ForwardVirtualState(node);
break;
case IrOpcode::kFinishRegion:
ProcessFinishRegion(node);
break;
case IrOpcode::kStoreField:
ProcessStoreField(node);
break;
case IrOpcode::kLoadField:
ProcessLoadField(node);
break;
case IrOpcode::kStoreElement:
ProcessStoreElement(node);
break;
case IrOpcode::kLoadElement:
ProcessLoadElement(node);
break;
case IrOpcode::kStart:
ProcessStart(node);
break;
case IrOpcode::kEffectPhi:
return ProcessEffectPhi(node);
break;
default:
if (node->op()->EffectInputCount() > 0) {
ForwardVirtualState(node);
}
ProcessAllocationUsers(node);
break;
}
return true;
}
void EscapeAnalysis::ProcessAllocationUsers(Node* node) {
for (Edge edge : node->input_edges()) {
Node* input = edge.to();
if (!NodeProperties::IsValueEdge(edge) &&
!NodeProperties::IsContextEdge(edge))
continue;
switch (node->opcode()) {
case IrOpcode::kStoreField:
case IrOpcode::kLoadField:
case IrOpcode::kStoreElement:
case IrOpcode::kLoadElement:
case IrOpcode::kFrameState:
case IrOpcode::kStateValues:
case IrOpcode::kReferenceEqual:
case IrOpcode::kFinishRegion:
case IrOpcode::kPhi:
break;
default:
VirtualState* state = virtual_states_[node->id()];
if (VirtualObject* obj = ResolveVirtualObject(state, input)) {
if (obj->ClearAllFields()) {
state->LastChangedAt(node);
}
}
break;
}
}
}
bool EscapeAnalysis::IsEffectBranchPoint(Node* node) {
int count = 0;
for (Edge edge : node->use_edges()) {
if (NodeProperties::IsEffectEdge(edge)) {
if (++count > 1) {
return true;
}
}
}
return false;
}
void EscapeAnalysis::ForwardVirtualState(Node* node) {
DCHECK_EQ(node->op()->EffectInputCount(), 1);
if (node->opcode() != IrOpcode::kLoadField &&
node->opcode() != IrOpcode::kLoadElement &&
node->opcode() != IrOpcode::kLoad && IsDanglingEffectNode(node)) {
PrintF("Dangeling effect node: #%d (%s)\n", node->id(),
node->op()->mnemonic());
UNREACHABLE();
}
Node* effect = NodeProperties::GetEffectInput(node);
// Break the cycle for effect phis.
if (effect->opcode() == IrOpcode::kEffectPhi) {
if (virtual_states_[effect->id()] == nullptr) {
virtual_states_[effect->id()] =
new (zone()) VirtualState(zone(), AliasCount());
}
}
DCHECK_NOT_NULL(virtual_states_[effect->id()]);
if (IsEffectBranchPoint(effect)) {
if (FLAG_trace_turbo_escape) {
PrintF("Copying object state %p from #%d (%s) to #%d (%s)\n",
static_cast<void*>(virtual_states_[effect->id()]), effect->id(),
effect->op()->mnemonic(), node->id(), node->op()->mnemonic());
}
if (!virtual_states_[node->id()]) {
virtual_states_[node->id()] =
new (zone()) VirtualState(*virtual_states_[effect->id()]);
} else {
virtual_states_[node->id()]->UpdateFrom(virtual_states_[effect->id()],
zone());
}
} else {
virtual_states_[node->id()] = virtual_states_[effect->id()];
if (FLAG_trace_turbo_escape) {
PrintF("Forwarding object state %p from #%d (%s) to #%d (%s)\n",
static_cast<void*>(virtual_states_[effect->id()]), effect->id(),
effect->op()->mnemonic(), node->id(), node->op()->mnemonic());
}
}
}
void EscapeAnalysis::ProcessStart(Node* node) {
DCHECK_EQ(node->opcode(), IrOpcode::kStart);
virtual_states_[node->id()] = new (zone()) VirtualState(zone(), AliasCount());
}
bool EscapeAnalysis::ProcessEffectPhi(Node* node) {
DCHECK_EQ(node->opcode(), IrOpcode::kEffectPhi);
bool changed = false;
VirtualState* mergeState = virtual_states_[node->id()];
if (!mergeState) {
mergeState = new (zone()) VirtualState(zone(), AliasCount());
virtual_states_[node->id()] = mergeState;
changed = true;
if (FLAG_trace_turbo_escape) {
PrintF("Effect Phi #%d got new states map %p.\n", node->id(),
static_cast<void*>(mergeState));
}
} else if (mergeState->GetLastChanged() != node) {
changed = true;
}
cache_->Clear();
if (FLAG_trace_turbo_escape) {
PrintF("At Effect Phi #%d, merging states into %p:", node->id(),
static_cast<void*>(mergeState));
}
for (int i = 0; i < node->op()->EffectInputCount(); ++i) {
Node* input = NodeProperties::GetEffectInput(node, i);
VirtualState* state = virtual_states_[input->id()];
if (state) {
cache_->states().push_back(state);
}
if (FLAG_trace_turbo_escape) {
PrintF(" %p (from %d %s)", static_cast<void*>(state), input->id(),
input->op()->mnemonic());
}
}
if (FLAG_trace_turbo_escape) {
PrintF("\n");
}
if (cache_->states().size() == 0) {
return changed;
}
changed = mergeState->MergeFrom(cache_, zone(), graph(), common(),
NodeProperties::GetControlInput(node)) ||
changed;
if (FLAG_trace_turbo_escape) {
PrintF("Merge %s the node.\n", changed ? "changed" : "did not change");
}
if (changed) {
mergeState->LastChangedAt(node);
escape_status_.Resize();
}
return changed;
}
void EscapeAnalysis::ProcessAllocation(Node* node) {
DCHECK_EQ(node->opcode(), IrOpcode::kAllocate);
ForwardVirtualState(node);
// Check if we have already processed this node.
if (virtual_states_[node->id()]->VirtualObjectFromAlias(
aliases_[node->id()])) {
return;
}
NumberMatcher size(node->InputAt(0));
DCHECK(node->InputAt(0)->opcode() != IrOpcode::kInt32Constant &&
node->InputAt(0)->opcode() != IrOpcode::kInt64Constant &&
node->InputAt(0)->opcode() != IrOpcode::kFloat32Constant &&
node->InputAt(0)->opcode() != IrOpcode::kFloat64Constant);
if (size.HasValue()) {
virtual_states_[node->id()]->SetVirtualObject(
aliases_[node->id()],
new (zone())
VirtualObject(node->id(), zone(), size.Value() / kPointerSize));
} else {
virtual_states_[node->id()]->SetVirtualObject(
aliases_[node->id()], new (zone()) VirtualObject(node->id(), zone()));
}
virtual_states_[node->id()]->LastChangedAt(node);
}
void EscapeAnalysis::ProcessFinishRegion(Node* node) {
DCHECK_EQ(node->opcode(), IrOpcode::kFinishRegion);
ForwardVirtualState(node);
Node* allocation = NodeProperties::GetValueInput(node, 0);
if (allocation->opcode() == IrOpcode::kAllocate) {
VirtualState* state = virtual_states_[node->id()];
if (!state->VirtualObjectFromAlias(aliases_[node->id()])) {
VirtualObject* vobj_alloc =
state->VirtualObjectFromAlias(aliases_[allocation->id()]);
DCHECK_NOT_NULL(vobj_alloc);
state->SetVirtualObject(aliases_[node->id()], vobj_alloc);
if (FLAG_trace_turbo_escape) {
PrintF("Linked finish region node #%d to node #%d\n", node->id(),
allocation->id());
}
state->LastChangedAt(node);
}
}
}
Node* EscapeAnalysis::replacement(NodeId id) {
if (id >= replacements_.size()) return nullptr;
return replacements_[id];
}
Node* EscapeAnalysis::replacement(Node* node) {
return replacement(node->id());
}
bool EscapeAnalysis::SetReplacement(Node* node, Node* rep) {
bool changed = replacements_[node->id()] != rep;
replacements_[node->id()] = rep;
return changed;
}
bool EscapeAnalysis::UpdateReplacement(VirtualState* state, Node* node,
Node* rep) {
if (SetReplacement(node, rep)) {
state->LastChangedAt(node);
if (FLAG_trace_turbo_escape) {
if (rep) {
PrintF("Replacement of #%d is #%d (%s)\n", node->id(), rep->id(),
rep->op()->mnemonic());
} else {
PrintF("Replacement of #%d cleared\n", node->id());
}
}
return true;
}
return false;
}
Node* EscapeAnalysis::ResolveReplacement(Node* node) {
while (replacement(node)) {
node = replacement(node);
}
return node;
}
Node* EscapeAnalysis::GetReplacement(Node* node) {
return GetReplacement(node->id());
}
Node* EscapeAnalysis::GetReplacement(NodeId id) {
Node* node = nullptr;
while (replacement(id)) {
node = replacement(id);
id = node->id();
}
return node;
}
bool EscapeAnalysis::IsVirtual(Node* node) {
if (node->id() >= escape_status_.size()) {
return false;
}
return escape_status_.IsVirtual(node);
}
bool EscapeAnalysis::IsEscaped(Node* node) {
if (node->id() >= escape_status_.size()) {
return false;
}
return escape_status_.IsEscaped(node);
}
bool EscapeAnalysis::SetEscaped(Node* node) {
return escape_status_.SetEscaped(node);
}
VirtualObject* EscapeAnalysis::GetVirtualObject(Node* at, NodeId id) {
if (VirtualState* states = virtual_states_[at->id()]) {
return states->VirtualObjectFromAlias(aliases_[id]);
}
return nullptr;
}
VirtualObject* EscapeAnalysis::ResolveVirtualObject(VirtualState* state,
Node* node) {
VirtualObject* obj = GetVirtualObject(state, ResolveReplacement(node));
while (obj && replacement(obj->id())) {
if (VirtualObject* next = GetVirtualObject(state, replacement(obj->id()))) {
obj = next;
} else {
break;
}
}
return obj;
}
bool EscapeAnalysis::CompareVirtualObjects(Node* left, Node* right) {
DCHECK(IsVirtual(left) && IsVirtual(right));
left = ResolveReplacement(left);
right = ResolveReplacement(right);
if (IsEquivalentPhi(left, right)) {
return true;
}
return false;
}
int EscapeAnalysis::OffsetFromAccess(Node* node) {
DCHECK(OpParameter<FieldAccess>(node).offset % kPointerSize == 0);
return OpParameter<FieldAccess>(node).offset / kPointerSize;
}
void EscapeAnalysis::ProcessLoadFromPhi(int offset, Node* from, Node* node,
VirtualState* state) {
if (FLAG_trace_turbo_escape) {
PrintF("Load #%d from phi #%d", node->id(), from->id());
}
cache_->fields().clear();
for (int i = 0; i < node->op()->ValueInputCount(); ++i) {
Node* input = NodeProperties::GetValueInput(node, i);
cache_->fields().push_back(input);
}
cache_->LoadVirtualObjectsForFieldsFrom(state, aliases_);
if (cache_->objects().size() == cache_->fields().size()) {
cache_->GetFields(offset);
if (cache_->fields().size() == cache_->objects().size()) {
Node* rep = replacement(node);
if (!rep || !IsEquivalentPhi(rep, cache_->fields())) {
int value_input_count = static_cast<int>(cache_->fields().size());
cache_->fields().push_back(NodeProperties::GetControlInput(from));
Node* phi = graph()->NewNode(
common()->Phi(MachineRepresentation::kTagged, value_input_count),
value_input_count + 1, &cache_->fields().front());
escape_status_.Resize();
SetReplacement(node, phi);
state->LastChangedAt(node);
if (FLAG_trace_turbo_escape) {
PrintF(" got phi created.\n");
}
} else if (FLAG_trace_turbo_escape) {
PrintF(" has already phi #%d.\n", rep->id());
}
} else if (FLAG_trace_turbo_escape) {
PrintF(" has incomplete field info.\n");
}
} else if (FLAG_trace_turbo_escape) {
PrintF(" has incomplete virtual object info.\n");
}
}
void EscapeAnalysis::ProcessLoadField(Node* node) {
DCHECK_EQ(node->opcode(), IrOpcode::kLoadField);
ForwardVirtualState(node);
Node* from = NodeProperties::GetValueInput(node, 0);
VirtualState* state = virtual_states_[node->id()];
if (VirtualObject* object = ResolveVirtualObject(state, from)) {
int offset = OffsetFromAccess(node);
if (!object->IsTracked()) return;
Node* value = object->GetField(offset);
if (value) {
value = ResolveReplacement(value);
}
// Record that the load has this alias.
UpdateReplacement(state, node, value);
} else {
if (from->opcode() == IrOpcode::kPhi &&
OpParameter<FieldAccess>(node).offset % kPointerSize == 0) {
int offset = OffsetFromAccess(node);
// Only binary phis are supported for now.
ProcessLoadFromPhi(offset, from, node, state);
}
}
}
void EscapeAnalysis::ProcessLoadElement(Node* node) {
DCHECK_EQ(node->opcode(), IrOpcode::kLoadElement);
ForwardVirtualState(node);
Node* from = NodeProperties::GetValueInput(node, 0);
VirtualState* state = virtual_states_[node->id()];
Node* index_node = node->InputAt(1);
NumberMatcher index(index_node);
DCHECK(index_node->opcode() != IrOpcode::kInt32Constant &&
index_node->opcode() != IrOpcode::kInt64Constant &&
index_node->opcode() != IrOpcode::kFloat32Constant &&
index_node->opcode() != IrOpcode::kFloat64Constant);
ElementAccess access = OpParameter<ElementAccess>(node);
if (index.HasValue()) {
int offset = index.Value() + access.header_size / kPointerSize;
if (VirtualObject* object = ResolveVirtualObject(state, from)) {
CHECK_GE(ElementSizeLog2Of(access.machine_type.representation()),
kPointerSizeLog2);
CHECK_EQ(access.header_size % kPointerSize, 0);
if (!object->IsTracked()) return;
Node* value = object->GetField(offset);
if (value) {
value = ResolveReplacement(value);
}
// Record that the load has this alias.
UpdateReplacement(state, node, value);
} else if (from->opcode() == IrOpcode::kPhi) {
ElementAccess access = OpParameter<ElementAccess>(node);
int offset = index.Value() + access.header_size / kPointerSize;
ProcessLoadFromPhi(offset, from, node, state);
}
} else {
// We have a load from a non-const index, cannot eliminate object.
if (SetEscaped(from)) {
if (FLAG_trace_turbo_escape) {
PrintF(
"Setting #%d (%s) to escaped because store element #%d to "
"non-const "
"index #%d (%s)\n",
from->id(), from->op()->mnemonic(), node->id(), index_node->id(),
index_node->op()->mnemonic());
}
}
}
}
void EscapeAnalysis::ProcessStoreField(Node* node) {
DCHECK_EQ(node->opcode(), IrOpcode::kStoreField);
ForwardVirtualState(node);
Node* to = NodeProperties::GetValueInput(node, 0);
Node* val = NodeProperties::GetValueInput(node, 1);
VirtualState* state = virtual_states_[node->id()];
if (VirtualObject* obj = ResolveVirtualObject(state, to)) {
if (!obj->IsTracked()) return;
int offset = OffsetFromAccess(node);
if (obj->SetField(offset, ResolveReplacement(val))) {
state->LastChangedAt(node);
}
}
}
void EscapeAnalysis::ProcessStoreElement(Node* node) {
DCHECK_EQ(node->opcode(), IrOpcode::kStoreElement);
ForwardVirtualState(node);
Node* to = NodeProperties::GetValueInput(node, 0);
Node* index_node = node->InputAt(1);
NumberMatcher index(index_node);
DCHECK(index_node->opcode() != IrOpcode::kInt32Constant &&
index_node->opcode() != IrOpcode::kInt64Constant &&
index_node->opcode() != IrOpcode::kFloat32Constant &&
index_node->opcode() != IrOpcode::kFloat64Constant);
ElementAccess access = OpParameter<ElementAccess>(node);
Node* val = NodeProperties::GetValueInput(node, 2);
if (index.HasValue()) {
int offset = index.Value() + access.header_size / kPointerSize;
VirtualState* states = virtual_states_[node->id()];
if (VirtualObject* obj = ResolveVirtualObject(states, to)) {
if (!obj->IsTracked()) return;
CHECK_GE(ElementSizeLog2Of(access.machine_type.representation()),
kPointerSizeLog2);
CHECK_EQ(access.header_size % kPointerSize, 0);
if (obj->SetField(offset, ResolveReplacement(val))) {
states->LastChangedAt(node);
}
}
} else {
// We have a store to a non-const index, cannot eliminate object.
if (SetEscaped(to)) {
if (FLAG_trace_turbo_escape) {
PrintF(
"Setting #%d (%s) to escaped because store element #%d to "
"non-const "
"index #%d (%s)\n",
to->id(), to->op()->mnemonic(), node->id(), index_node->id(),
index_node->op()->mnemonic());
}
}
}
}
Node* EscapeAnalysis::GetOrCreateObjectState(Node* effect, Node* node) {
if ((node->opcode() == IrOpcode::kFinishRegion ||
node->opcode() == IrOpcode::kAllocate) &&
IsVirtual(node)) {
if (VirtualObject* vobj =
ResolveVirtualObject(virtual_states_[effect->id()], node)) {
if (Node* object_state = vobj->GetObjectState()) {
return object_state;
} else {
cache_->fields().clear();
for (size_t i = 0; i < vobj->field_count(); ++i) {
if (Node* field = vobj->GetField(i)) {
cache_->fields().push_back(field);
}
}
int input_count = static_cast<int>(cache_->fields().size());
Node* new_object_state =
graph()->NewNode(common()->ObjectState(input_count, vobj->id()),
input_count, &cache_->fields().front());
vobj->SetObjectState(new_object_state);
if (FLAG_trace_turbo_escape) {
PrintF(
"Creating object state #%d for vobj %p (from node #%d) at effect "
"#%d\n",
new_object_state->id(), static_cast<void*>(vobj), node->id(),
effect->id());
}
// Now fix uses of other objects.
for (size_t i = 0; i < vobj->field_count(); ++i) {
if (Node* field = vobj->GetField(i)) {
if (Node* field_object_state =
GetOrCreateObjectState(effect, field)) {
NodeProperties::ReplaceValueInput(
new_object_state, field_object_state, static_cast<int>(i));
}
}
}
return new_object_state;
}
}
}
return nullptr;
}
void EscapeAnalysis::DebugPrintObject(VirtualObject* object, Alias alias) {
PrintF(" Alias @%d: Object #%d with %zu fields\n", alias, object->id(),
object->field_count());
for (size_t i = 0; i < object->field_count(); ++i) {
if (Node* f = object->GetField(i)) {
PrintF(" Field %zu = #%d (%s)\n", i, f->id(), f->op()->mnemonic());
}
}
}
void EscapeAnalysis::DebugPrintState(VirtualState* state) {
PrintF("Dumping object state %p\n", static_cast<void*>(state));
for (Alias alias = 0; alias < AliasCount(); ++alias) {
if (VirtualObject* object = state->VirtualObjectFromAlias(alias)) {
DebugPrintObject(object, alias);
}
}
}
void EscapeAnalysis::DebugPrint() {
ZoneVector<VirtualState*> object_states(zone());
for (NodeId id = 0; id < virtual_states_.size(); id++) {
if (VirtualState* states = virtual_states_[id]) {
if (std::find(object_states.begin(), object_states.end(), states) ==
object_states.end()) {
object_states.push_back(states);
}
}
}
for (size_t n = 0; n < object_states.size(); n++) {
DebugPrintState(object_states[n]);
}
}
VirtualObject* EscapeAnalysis::GetVirtualObject(VirtualState* state,
Node* node) {
if (node->id() >= aliases_.size()) return nullptr;
Alias alias = aliases_[node->id()];
if (alias >= state->size()) return nullptr;
return state->VirtualObjectFromAlias(alias);
}
} // namespace compiler
} // namespace internal
} // namespace v8