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LibJS: Use a premade shape for normal function object prototypes

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This avoids one shape allocation per function instantiation.
This commit is contained in:
Andreas Kling 2025-03-25 19:16:11 +00:00
parent 718d6e6927
commit a06d1f5a93
3 changed files with 14 additions and 2 deletions
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4
Libraries/LibJS/Runtime/ECMAScriptFunctionObject.cpp
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@ -354,8 +354,8 @@ void ECMAScriptFunctionObject::initialize(Realm& realm)
Object* prototype = nullptr;
switch (m_kind) {
case FunctionKind::Normal:
prototype = Object::create_prototype(realm, realm.intrinsics().object_prototype());
MUST(prototype->define_property_or_throw(vm.names.constructor, { .value = this, .writable = true, .enumerable = false, .configurable = true }));
prototype = Object::create_with_premade_shape(realm.intrinsics().normal_function_prototype_shape());
prototype->put_direct(realm.intrinsics().normal_function_prototype_constructor_offset(), this);
break;
case FunctionKind::Generator:
// prototype is "g1.prototype" in figure-2 (https://tc39.es/ecma262/img/figure-2.png)

6
Libraries/LibJS/Runtime/Intrinsics.cpp
View file

@ -198,6 +198,11 @@ void Intrinsics::initialize_intrinsics(Realm& realm)
m_iterator_result_object_value_offset = m_iterator_result_object_shape->lookup(vm.names.value.to_string_or_symbol()).value().offset;
m_iterator_result_object_done_offset = m_iterator_result_object_shape->lookup(vm.names.done.to_string_or_symbol()).value().offset;
m_normal_function_prototype_shape = heap().allocate<Shape>(realm);
m_normal_function_prototype_shape->set_prototype_without_transition(m_object_prototype);
m_normal_function_prototype_shape->add_property_without_transition(vm.names.constructor, Attribute::Writable | Attribute::Configurable);
m_normal_function_prototype_constructor_offset = m_normal_function_prototype_shape->lookup(vm.names.constructor.to_string_or_symbol()).value().offset;
// Normally Realm::create() takes care of this, but these are allocated via Heap::allocate().
m_function_prototype->initialize(realm);
m_object_prototype->initialize(realm);
@ -366,6 +371,7 @@ void Intrinsics::visit_edges(Visitor& visitor)
visitor.visit(m_empty_object_shape);
visitor.visit(m_new_object_shape);
visitor.visit(m_iterator_result_object_shape);
visitor.visit(m_normal_function_prototype_shape);
visitor.visit(m_proxy_constructor);
visitor.visit(m_async_from_sync_iterator_prototype);
visitor.visit(m_async_generator_prototype);

6
Libraries/LibJS/Runtime/Intrinsics.h
View file

@ -28,6 +28,9 @@ public:
[[nodiscard]] u32 iterator_result_object_value_offset() { return m_iterator_result_object_value_offset; }
[[nodiscard]] u32 iterator_result_object_done_offset() { return m_iterator_result_object_done_offset; }
[[nodiscard]] GC::Ref<Shape> normal_function_prototype_shape() { return *m_normal_function_prototype_shape; }
[[nodiscard]] u32 normal_function_prototype_constructor_offset() const { return m_normal_function_prototype_constructor_offset; }
// Not included in JS_ENUMERATE_NATIVE_OBJECTS due to missing distinct prototype
GC::Ref<ProxyConstructor> proxy_constructor() { return *m_proxy_constructor; }
@ -133,6 +136,9 @@ private:
u32 m_iterator_result_object_value_offset { 0 };
u32 m_iterator_result_object_done_offset { 0 };
GC::Ptr<Shape> m_normal_function_prototype_shape;
u32 m_normal_function_prototype_constructor_offset { 0 };
// Not included in JS_ENUMERATE_NATIVE_OBJECTS due to missing distinct prototype
GC::Ptr<ProxyConstructor> m_proxy_constructor;