From d3dfd554721aac21c20c7cbe75a98188bf39d29d Mon Sep 17 00:00:00 2001 From: Andreas Kling Date: Sat, 17 Oct 2020 23:13:37 +0200 Subject: [PATCH] LibJS: Prebake the empty object ({}) with a prototype Instead of performing a prototype transition for every new object we create via {}, prebake the object returned by Object::create_empty() with a shape with ObjectPrototype as the prototype. We also prebake the shape for the object assigned to the "prototype" property of new ScriptFunction objects, since those are extremely common and that code broke from this change anyway. This avoid a large number of transitions and is a small speed-up on test-js. --- Libraries/LibJS/Runtime/GlobalObject.cpp | 9 +++++++++ Libraries/LibJS/Runtime/GlobalObject.h | 5 +++++ Libraries/LibJS/Runtime/Object.cpp | 9 +++++++-- Libraries/LibJS/Runtime/Object.h | 1 + Libraries/LibJS/Runtime/ScriptFunction.cpp | 4 ++-- 5 files changed, 24 insertions(+), 4 deletions(-) diff --git a/Libraries/LibJS/Runtime/GlobalObject.cpp b/Libraries/LibJS/Runtime/GlobalObject.cpp index 581cf69405..3a3a50885a 100644 --- a/Libraries/LibJS/Runtime/GlobalObject.cpp +++ b/Libraries/LibJS/Runtime/GlobalObject.cpp @@ -84,6 +84,13 @@ void GlobalObject::initialize() m_object_prototype = heap().allocate_without_global_object(*this); m_function_prototype = heap().allocate_without_global_object(*this); + m_new_object_shape = vm.heap().allocate(*this, *this); + m_new_object_shape->set_prototype_without_transition(m_object_prototype); + + m_new_script_function_prototype_object_shape = vm.heap().allocate(*this, *this); + m_new_script_function_prototype_object_shape->set_prototype_without_transition(m_object_prototype); + m_new_script_function_prototype_object_shape->add_property_without_transition(vm.names.constructor, Attribute::Writable | Attribute::Configurable); + static_cast(m_function_prototype)->initialize(*this); static_cast(m_object_prototype)->initialize(*this); @@ -143,6 +150,8 @@ void GlobalObject::visit_children(Visitor& visitor) Object::visit_children(visitor); visitor.visit(m_empty_object_shape); + visitor.visit(m_new_object_shape); + visitor.visit(m_new_script_function_prototype_object_shape); #define __JS_ENUMERATE(ClassName, snake_name, PrototypeName, ConstructorName) \ visitor.visit(m_##snake_name##_constructor); diff --git a/Libraries/LibJS/Runtime/GlobalObject.h b/Libraries/LibJS/Runtime/GlobalObject.h index d45c1f74f5..d3aa83855d 100644 --- a/Libraries/LibJS/Runtime/GlobalObject.h +++ b/Libraries/LibJS/Runtime/GlobalObject.h @@ -45,6 +45,9 @@ public: Shape* empty_object_shape() { return m_empty_object_shape; } + Shape* new_object_shape() { return m_new_object_shape; } + Shape* new_script_function_prototype_object_shape() { return m_new_script_function_prototype_object_shape; } + #define __JS_ENUMERATE(ClassName, snake_name, PrototypeName, ConstructorName) \ ConstructorName* snake_name##_constructor() { return m_##snake_name##_constructor; } \ Object* snake_name##_prototype() { return m_##snake_name##_prototype; } @@ -71,6 +74,8 @@ private: NonnullOwnPtr m_console; Shape* m_empty_object_shape { nullptr }; + Shape* m_new_object_shape { nullptr }; + Shape* m_new_script_function_prototype_object_shape { nullptr }; #define __JS_ENUMERATE(ClassName, snake_name, PrototypeName, ConstructorName) \ ConstructorName* m_##snake_name##_constructor { nullptr }; \ diff --git a/Libraries/LibJS/Runtime/Object.cpp b/Libraries/LibJS/Runtime/Object.cpp index 66bff30be0..9fd86bf43a 100644 --- a/Libraries/LibJS/Runtime/Object.cpp +++ b/Libraries/LibJS/Runtime/Object.cpp @@ -84,7 +84,7 @@ PropertyDescriptor PropertyDescriptor::from_dictionary(VM& vm, const Object& obj Object* Object::create_empty(GlobalObject& global_object) { - return global_object.heap().allocate(global_object, *global_object.object_prototype()); + return global_object.heap().allocate(global_object, *global_object.new_object_shape()); } Object::Object(GlobalObjectTag) @@ -99,12 +99,17 @@ Object::Object(ConstructWithoutPrototypeTag, GlobalObject& global_object) } Object::Object(Object& prototype) - : Cell() { m_shape = prototype.global_object().empty_object_shape(); set_prototype(&prototype); } +Object::Object(Shape& shape) + : m_shape(&shape) +{ + m_storage.resize(shape.property_count()); +} + void Object::initialize(GlobalObject&) { } diff --git a/Libraries/LibJS/Runtime/Object.h b/Libraries/LibJS/Runtime/Object.h index 001255db42..a1d76957a3 100644 --- a/Libraries/LibJS/Runtime/Object.h +++ b/Libraries/LibJS/Runtime/Object.h @@ -63,6 +63,7 @@ public: static Object* create_empty(GlobalObject&); explicit Object(Object& prototype); + explicit Object(Shape&); virtual void initialize(GlobalObject&) override; virtual ~Object(); diff --git a/Libraries/LibJS/Runtime/ScriptFunction.cpp b/Libraries/LibJS/Runtime/ScriptFunction.cpp index 4218045dd0..c3575b8c48 100644 --- a/Libraries/LibJS/Runtime/ScriptFunction.cpp +++ b/Libraries/LibJS/Runtime/ScriptFunction.cpp @@ -69,8 +69,8 @@ void ScriptFunction::initialize(GlobalObject& global_object) auto& vm = this->vm(); Function::initialize(global_object); if (!m_is_arrow_function) { - Object* prototype = Object::create_empty(global_object); - prototype->define_property_without_transition(vm.names.constructor, this, Attribute::Writable | Attribute::Configurable); + Object* prototype = vm.heap().allocate(global_object, *global_object.new_script_function_prototype_object_shape()); + prototype->define_property(vm.names.constructor, this, Attribute::Writable | Attribute::Configurable); define_property(vm.names.prototype, prototype, 0); } define_native_property(vm.names.length, length_getter, nullptr, Attribute::Configurable);