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Unified Diff: src/hydrogen.cc

Issue 1062163005: track global accesses to constant types (Closed) Base URL: https://chromium.googlesource.com/v8/v8.git@master
Patch Set: Created 5 years, 8 months ago
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Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 97d604a7c248ee317dfc0b9635eedeaa01cf68fa..7b91d9846188f52732ef538ef0c57175c421d7f8 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -5396,8 +5396,10 @@ void HOptimizedGraphBuilder::VisitVariableProxy(VariableProxy* expr) {
if (type == kUseCell) {
Handle<PropertyCell> cell = it.GetPropertyCell();
- top_info()->dependencies()->AssumePropertyCell(cell);
- if (it.property_details().cell_type() == PropertyCellType::kConstant) {
+ auto cell_type = it.property_details().cell_type();
+ if (cell_type == PropertyCellType::kConstant ||
+ cell_type == PropertyCellType::kUndefined) {
+ top_info()->dependencies()->AssumePropertyCell(cell);
Handle<Object> constant_object(cell->value(), isolate());
if (constant_object->IsConsString()) {
constant_object =
@@ -5406,9 +5408,40 @@ void HOptimizedGraphBuilder::VisitVariableProxy(VariableProxy* expr) {
HConstant* constant = New<HConstant>(constant_object);
return ast_context()->ReturnInstruction(constant, expr->id());
} else {
+ auto access = HObjectAccess::ForPropertyCellValue();
+ UniqueSet<Map>* field_maps = nullptr;
+ if (cell_type == PropertyCellType::kConstantType) {
+ switch (cell->GetConstantType()) {
+ case PropertyCellConstantType::kSmi:
+ access = access.WithRepresentation(Representation::Smi());
+ break;
+ case PropertyCellConstantType::kStableMap: {
+ // Check that the map really is stable. The heap object could
+ // have mutated without the cell updating state.
+ Handle<Map> map(HeapObject::cast(cell->value())->map());
+ if (map->is_stable()) {
+ access =
+ access.WithRepresentation(Representation::HeapObject());
+ field_maps = new (zone())
+ UniqueSet<Map>(Unique<Map>::CreateImmovable(map), zone());
+ } else {
+ auto dictionary = handle(global->property_dictionary());
+ cell = PropertyCell::InvalidateEntry(dictionary,
+ it.dictionary_entry());
+ }
+ break;
+ }
+ }
+ }
+ top_info()->dependencies()->AssumePropertyCell(cell);
HConstant* cell_constant = Add<HConstant>(cell);
- HLoadNamedField* instr = New<HLoadNamedField>(
- cell_constant, nullptr, HObjectAccess::ForPropertyCellValue());
+ HLoadNamedField* instr;
+ if (field_maps == nullptr) {
+ instr = New<HLoadNamedField>(cell_constant, nullptr, access);
+ } else {
+ instr = New<HLoadNamedField>(cell_constant, nullptr, access,
+ field_maps, HType::HeapObject());
+ }
instr->ClearDependsOnFlag(kInobjectFields);
instr->SetDependsOnFlag(kGlobalVars);
return ast_context()->ReturnInstruction(instr, expr->id());
@@ -6563,7 +6596,9 @@ void HOptimizedGraphBuilder::HandleGlobalVariableAssignment(
if (type == kUseCell) {
Handle<PropertyCell> cell = it.GetPropertyCell();
top_info()->dependencies()->AssumePropertyCell(cell);
- if (it.property_details().cell_type() == PropertyCellType::kConstant) {
+ auto cell_type = it.property_details().cell_type();
+ if (cell_type == PropertyCellType::kConstant ||
+ cell_type == PropertyCellType::kUndefined) {
Handle<Object> constant(cell->value(), isolate());
if (value->IsConstant()) {
HConstant* c_value = HConstant::cast(value);
@@ -6587,8 +6622,30 @@ void HOptimizedGraphBuilder::HandleGlobalVariableAssignment(
}
}
HConstant* cell_constant = Add<HConstant>(cell);
- HInstruction* instr = Add<HStoreNamedField>(
- cell_constant, HObjectAccess::ForPropertyCellValue(), value);
+ auto access = HObjectAccess::ForPropertyCellValue();
+ if (cell_type == PropertyCellType::kConstantType) {
+ switch (cell->GetConstantType()) {
+ case PropertyCellConstantType::kSmi:
+ access = access.WithRepresentation(Representation::Smi());
+ break;
+ case PropertyCellConstantType::kStableMap: {
+ // Check that the map really is stable. The heap object could have
+ // mutated without the cell updating state.
+ Handle<Map> map(HeapObject::cast(cell->value())->map());
+ if (map->is_stable()) {
+ Add<HCheckHeapObject>(value);
+ value = Add<HCheckMaps>(value, map);
+ access = access.WithRepresentation(Representation::HeapObject());
+ } else {
+ auto dictionary = handle(global->property_dictionary());
+ cell = PropertyCell::InvalidateEntry(dictionary,
+ it.dictionary_entry());
+ }
+ break;
+ }
+ }
+ }
+ HInstruction* instr = Add<HStoreNamedField>(cell_constant, access, value);
instr->ClearChangesFlag(kInobjectFields);
instr->SetChangesFlag(kGlobalVars);
if (instr->HasObservableSideEffects()) {
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