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LibJS: Key shape transitions on both property name and attributes

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This allows us to cache forward transitions that reconfigure existing
properties as well, leading to better shape reuse.
This commit is contained in:
Andreas Kling 2020-04-10 16:33:44 +02:00
parent 8cbb8491cb
commit 0fea525373
Notes: sideshowbarker 2024-07-19 07:44:29 +09:00
2 changed files with 30 additions and 11 deletions
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20
Libraries/LibJS/Runtime/Shape.cpp
View file

@ -31,21 +31,21 @@ namespace JS {
Shape* Shape::create_put_transition(const FlyString& property_name, u8 attributes)
{
auto* new_shape = m_forward_transitions.get(property_name).value_or(nullptr);
if (new_shape && new_shape->m_attributes == attributes)
return new_shape;
new_shape = heap().allocate<Shape>(this, property_name, attributes, TransitionType::Put);
m_forward_transitions.set(property_name, new_shape);
TransitionKey key { property_name, attributes };
if (auto* existing_shape = m_forward_transitions.get(key).value_or(nullptr))
return existing_shape;
auto* new_shape = heap().allocate<Shape>(this, property_name, attributes, TransitionType::Put);
m_forward_transitions.set(key, new_shape);
return new_shape;
}
Shape* Shape::create_configure_transition(const FlyString& property_name, u8 attributes)
{
auto* new_shape = m_forward_transitions.get(property_name).value_or(nullptr);
if (new_shape && new_shape->m_attributes == attributes)
return new_shape;
new_shape = heap().allocate<Shape>(this, property_name, attributes, TransitionType::Configure);
m_forward_transitions.set(property_name, new_shape);
TransitionKey key { property_name, attributes };
if (auto* existing_shape = m_forward_transitions.get(key).value_or(nullptr))
return existing_shape;
auto* new_shape = heap().allocate<Shape>(this, property_name, attributes, TransitionType::Configure);
m_forward_transitions.set(key, new_shape);
return new_shape;
}

21
Libraries/LibJS/Runtime/Shape.h
View file

@ -48,6 +48,17 @@ struct PropertyMetadata {
u8 attributes { 0 };
};
struct TransitionKey {
FlyString property_name;
u8 attributes { 0 };
bool operator==(const TransitionKey& other) const
{
return property_name == other.property_name
&& attributes == other.attributes;
}
};
class Shape final : public Cell {
public:
virtual ~Shape() override;
@ -84,7 +95,7 @@ private:
mutable OwnPtr<HashMap<FlyString, PropertyMetadata>> m_property_table;
HashMap<FlyString, Shape*> m_forward_transitions;
HashMap<TransitionKey, Shape*> m_forward_transitions;
Shape* m_previous { nullptr };
FlyString m_property_name;
u8 m_attributes { 0 };
@ -93,3 +104,11 @@ private:
};
}
template<>
struct AK::Traits<JS::TransitionKey> : public GenericTraits<JS::TransitionKey> {
static unsigned hash(const JS::TransitionKey& key)
{
return pair_int_hash(int_hash(key.attributes), key.property_name.hash());
}
};