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Introduce NewSlowJSObjectWithNullProto for debugger use

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NewJSObjectWithNullProto has use cases outside of the debugger. We
previously changed it to create dictionary mode objects, which affects
the performance of non-debugger use cases. This change partially
reverts that change by differentiating between use cases.

Fixed: chromium:1266160
Change-Id: I875073bdc062cf187ef24da62324f743169d2e29
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3257706
Auto-Submit: Yang Guo <yangguo@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77671}
This commit is contained in:
Yang Guo 2021-11-03 08:36:33 +01:00 committed by V8 LUCI CQ
parent f8117f3589
commit 042449fd88
5 changed files with 18 additions and 7 deletions
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2
src/debug/debug-evaluate.cc
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@ -142,7 +142,7 @@ MaybeHandle<Object> DebugEvaluate::WithTopmostArguments(Isolate* isolate,
Context::cast(it.frame()->context()).native_context(), isolate);
// Materialize arguments as property on an extension object.
Handle<JSObject> materialized = factory->NewJSObjectWithNullProto();
Handle<JSObject> materialized = factory->NewSlowJSObjectWithNullProto();
Handle<String> arguments_str = factory->arguments_string();
JSObject::SetOwnPropertyIgnoreAttributes(
materialized, arguments_str,

4
src/debug/debug-scopes.cc
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@ -556,7 +556,7 @@ Handle<JSObject> ScopeIterator::ScopeObject(Mode mode) {
return WithContextExtension();
}
Handle<JSObject> scope = isolate_->factory()->NewJSObjectWithNullProto();
Handle<JSObject> scope = isolate_->factory()->NewSlowJSObjectWithNullProto();
auto visitor = [=](Handle<String> name, Handle<Object> value,
ScopeType scope_type) {
if (value->IsTheHole(isolate_)) {
@ -901,7 +901,7 @@ bool ScopeIterator::VisitLocals(const Visitor& visitor, Mode mode,
Handle<JSObject> ScopeIterator::WithContextExtension() {
DCHECK(context_->IsWithContext());
if (context_->extension_receiver().IsJSProxy()) {
return isolate_->factory()->NewJSObjectWithNullProto();
return isolate_->factory()->NewSlowJSObjectWithNullProto();
}
return handle(JSObject::cast(context_->extension_receiver()), isolate_);
}

6
src/debug/debug-wasm-objects.cc
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@ -628,7 +628,7 @@ class ContextProxy {
public:
static Handle<JSObject> Create(WasmFrame* frame) {
Isolate* isolate = frame->isolate();
auto object = isolate->factory()->NewJSObjectWithNullProto();
auto object = isolate->factory()->NewSlowJSObjectWithNullProto();
Handle<WasmInstanceObject> instance(frame->wasm_instance(), isolate);
JSObject::AddProperty(isolate, object, "instance", instance, FROZEN);
Handle<WasmModuleObject> module_object(instance->module_object(), isolate);
@ -692,7 +692,7 @@ class DebugWasmScopeIterator final : public debug::ScopeIterator {
case debug::ScopeIterator::ScopeTypeModule: {
Handle<WasmInstanceObject> instance(frame_->wasm_instance(), isolate);
Handle<JSObject> object =
isolate->factory()->NewJSObjectWithNullProto();
isolate->factory()->NewSlowJSObjectWithNullProto();
JSObject::AddProperty(isolate, object, "instance", instance, FROZEN);
Handle<JSObject> module_object(instance->module_object(), isolate);
JSObject::AddProperty(isolate, object, "module", module_object, FROZEN);
@ -725,7 +725,7 @@ class DebugWasmScopeIterator final : public debug::ScopeIterator {
return Utils::ToLocal(LocalsProxy::Create(frame_));
}
case debug::ScopeIterator::ScopeTypeWasmExpressionStack: {
auto object = isolate->factory()->NewJSObjectWithNullProto();
auto object = isolate->factory()->NewSlowJSObjectWithNullProto();
auto stack = StackProxy::Create(frame_);
JSObject::AddProperty(isolate, object, "stack", stack, FROZEN);
return Utils::ToLocal(object);

11
src/heap/factory.cc
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@ -2302,12 +2302,21 @@ Handle<JSObject> Factory::NewJSObject(Handle<JSFunction> constructor,
return NewJSObjectFromMap(map, allocation);
}
Handle<JSObject> Factory::NewJSObjectWithNullProto() {
Handle<JSObject> Factory::NewSlowJSObjectWithNullProto() {
Handle<JSObject> result =
NewSlowJSObjectFromMap(isolate()->slow_object_with_null_prototype_map());
return result;
}
Handle<JSObject> Factory::NewJSObjectWithNullProto() {
Handle<JSObject> result = NewJSObject(isolate()->object_function());
Handle<Map> new_map = Map::Copy(
isolate(), Handle<Map>(result->map(), isolate()), "ObjectWithNullProto");
Map::SetPrototype(isolate(), new_map, null_value());
JSObject::MigrateToMap(isolate(), result, new_map);
return result;
}
Handle<JSGlobalObject> Factory::NewJSGlobalObject(
Handle<JSFunction> constructor) {
DCHECK(constructor->has_initial_map());

2
src/heap/factory.h
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@ -489,6 +489,8 @@ class V8_EXPORT_PRIVATE Factory : public FactoryBase<Factory> {
AllocationType allocation = AllocationType::kYoung);
// JSObject without a prototype.
Handle<JSObject> NewJSObjectWithNullProto();
// JSObject without a prototype, in dictionary mode.
Handle<JSObject> NewSlowJSObjectWithNullProto();
// Global objects are pretenured and initialized based on a constructor.
Handle<JSGlobalObject> NewJSGlobalObject(Handle<JSFunction> constructor);