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LibJS: Only allocate space for Object private elements if needed

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Most JavaScript objects don't have private elements, so this reduces the
size of typical JS::Object instances by two pointers.
This commit is contained in:
Andreas Kling 2021-12-08 09:38:31 +01:00
parent 444a7eb929
commit 212319b25e
2 changed files with 15 additions and 6 deletions
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19
Userland/Libraries/LibJS/Runtime/Object.cpp
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@ -470,7 +470,10 @@ ThrowCompletionOr<Object*> Object::copy_data_properties(Value source, HashTable<
// 7.3.26 PrivateElementFind ( O, P ), https://tc39.es/ecma262/#sec-privateelementfind // 7.3.26 PrivateElementFind ( O, P ), https://tc39.es/ecma262/#sec-privateelementfind
PrivateElement* Object::private_element_find(PrivateName const& name) PrivateElement* Object::private_element_find(PrivateName const& name)
{ {
auto element = m_private_elements.find_if([&](auto const& element) { if (!m_private_elements)
return nullptr;
auto element = m_private_elements->find_if([&](auto const& element) {
return element.key == name; return element.key == name;
}); });
@ -485,7 +488,9 @@ ThrowCompletionOr<void> Object::private_field_add(PrivateName const& name, Value
{ {
if (auto* entry = private_element_find(name); entry) if (auto* entry = private_element_find(name); entry)
return vm().throw_completion<TypeError>(global_object(), ErrorType::PrivateFieldAlreadyDeclared, name.description); return vm().throw_completion<TypeError>(global_object(), ErrorType::PrivateFieldAlreadyDeclared, name.description);
m_private_elements.empend(name, PrivateElement::Kind::Field, value); if (!m_private_elements)
m_private_elements = make<Vector<PrivateElement>>();
m_private_elements->empend(name, PrivateElement::Kind::Field, value);
return {}; return {};
} }
@ -495,7 +500,9 @@ ThrowCompletionOr<void> Object::private_method_or_accessor_add(PrivateElement el
VERIFY(element.kind == PrivateElement::Kind::Method || element.kind == PrivateElement::Kind::Accessor); VERIFY(element.kind == PrivateElement::Kind::Method || element.kind == PrivateElement::Kind::Accessor);
if (auto* entry = private_element_find(element.key); entry) if (auto* entry = private_element_find(element.key); entry)
return vm().throw_completion<TypeError>(global_object(), ErrorType::PrivateFieldAlreadyDeclared, element.key.description); return vm().throw_completion<TypeError>(global_object(), ErrorType::PrivateFieldAlreadyDeclared, element.key.description);
m_private_elements.append(move(element)); if (!m_private_elements)
m_private_elements = make<Vector<PrivateElement>>();
m_private_elements->append(move(element));
return {}; return {};
} }
@ -1187,8 +1194,10 @@ void Object::visit_edges(Cell::Visitor& visitor)
visitor.visit(value); visitor.visit(value);
}); });
for (auto& private_element : m_private_elements) if (m_private_elements) {
visitor.visit(private_element.value); for (auto& private_element : *m_private_elements)
visitor.visit(private_element.value);
}
} }
// 7.1.1.1 OrdinaryToPrimitive ( O, hint ), https://tc39.es/ecma262/#sec-ordinarytoprimitive // 7.1.1.1 OrdinaryToPrimitive ( O, hint ), https://tc39.es/ecma262/#sec-ordinarytoprimitive

2
Userland/Libraries/LibJS/Runtime/Object.h
View file

@ -208,7 +208,7 @@ private:
Shape* m_shape { nullptr }; Shape* m_shape { nullptr };
Vector<Value> m_storage; Vector<Value> m_storage;
IndexedProperties m_indexed_properties; IndexedProperties m_indexed_properties;
Vector<PrivateElement> m_private_elements; // [[PrivateElements]] OwnPtr<Vector<PrivateElement>> m_private_elements; // [[PrivateElements]]
}; };
} }