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LibJS: Don't create lexical environment for native (C++) function calls

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This was creating a ton of pointless busywork for the garbage collector
and can be avoided simply by tolerating that the current call frame has
a null scope object for the duration of a NativeFunction activation.
This commit is contained in:
Andreas Kling 2021-06-09 20:52:35 +02:00
parent d0bed24ca1
commit d69cd3f5bf
2 changed files with 16 additions and 9 deletions
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22
Userland/Libraries/LibJS/Runtime/VM.cpp
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@ -399,12 +399,14 @@ Value VM::construct(Function& function, Function& new_target, Optional<MarkedVal
call_frame.arguments.append(arguments.value().values());
auto* environment = function.create_environment();
call_frame.scope = environment;
environment->set_new_target(&new_target);
if (environment)
environment->set_new_target(&new_target);
Object* new_object = nullptr;
if (function.constructor_kind() == Function::ConstructorKind::Base) {
new_object = Object::create_empty(global_object);
environment->bind_this_value(global_object, new_object);
if (environment)
environment->bind_this_value(global_object, new_object);
if (exception())
return {};
auto prototype = new_target.get(names.prototype);
@ -422,15 +424,18 @@ Value VM::construct(Function& function, Function& new_target, Optional<MarkedVal
call_frame.this_value = this_value;
auto result = function.construct(new_target);
this_value = call_frame.scope->get_this_binding(global_object);
if (environment)
this_value = environment->get_this_binding(global_object);
pop_call_frame();
call_frame_popper.disarm();
// If we are constructing an instance of a derived class,
// set the prototype on objects created by constructors that return an object (i.e. NativeFunction subclasses).
if (function.constructor_kind() == Function::ConstructorKind::Base && new_target.constructor_kind() == Function::ConstructorKind::Derived && result.is_object()) {
VERIFY(is<LexicalEnvironment>(current_scope()));
static_cast<LexicalEnvironment*>(current_scope())->replace_this_binding(result);
if (environment) {
VERIFY(is<LexicalEnvironment>(current_scope()));
static_cast<LexicalEnvironment*>(current_scope())->replace_this_binding(result);
}
auto prototype = new_target.get(names.prototype);
if (exception())
return {};
@ -507,8 +512,11 @@ Value VM::call_internal(Function& function, Value this_value, Optional<MarkedVal
auto* environment = function.create_environment();
call_frame.scope = environment;
VERIFY(environment->this_binding_status() == LexicalEnvironment::ThisBindingStatus::Uninitialized);
environment->bind_this_value(function.global_object(), call_frame.this_value);
if (environment) {
VERIFY(environment->this_binding_status() == LexicalEnvironment::ThisBindingStatus::Uninitialized);
environment->bind_this_value(function.global_object(), call_frame.this_value);
}
if (exception())
return {};