mirror of
https://github.com/LadybirdBrowser/ladybird.git
synced 2025-11-04 07:10:57 +00:00
1e90379008
This is similar to "unique" shapes, which were removed in commit
3d92c26445.
The key difference is that dictionary shapes don't have a serial number,
but instead have a "cacheable" flag.
Shapes become dictionaries after 64 transitions have occurred, at which
point no further transitions occur.
As long as properties are only added to a dictionary shape, it remains
cacheable. (Since if we've cached the shape pointer in an IC somewhere,
we know the IC is still valid.)
Deleting a property from a dictionary shape causes it to become an
uncacheable dictionary.
Note that deleting a property from a non-dictionary shape still performs
a delete transition.
This fixes an issue on Discord where Object.freeze() would eventually
OOM us, since they add more than 16000 properties to a single object
before freezing it.
It also yields a 15% speedup on Octane/pdfjs.js :^)
131 lines
4.3 KiB
C++
131 lines
4.3 KiB
C++
/*
|
|
* Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
|
|
*
|
|
* SPDX-License-Identifier: BSD-2-Clause
|
|
*/
|
|
|
|
#pragma once
|
|
|
|
#include <AK/HashMap.h>
|
|
#include <AK/OwnPtr.h>
|
|
#include <AK/StringView.h>
|
|
#include <AK/WeakPtr.h>
|
|
#include <AK/Weakable.h>
|
|
#include <LibJS/Forward.h>
|
|
#include <LibJS/Heap/Cell.h>
|
|
#include <LibJS/Runtime/PropertyAttributes.h>
|
|
#include <LibJS/Runtime/StringOrSymbol.h>
|
|
#include <LibJS/Runtime/Value.h>
|
|
|
|
namespace JS {
|
|
|
|
struct PropertyMetadata {
|
|
u32 offset { 0 };
|
|
PropertyAttributes attributes { 0 };
|
|
};
|
|
|
|
struct TransitionKey {
|
|
StringOrSymbol property_key;
|
|
PropertyAttributes attributes { 0 };
|
|
|
|
bool operator==(TransitionKey const& other) const
|
|
{
|
|
return property_key == other.property_key && attributes == other.attributes;
|
|
}
|
|
};
|
|
|
|
class Shape final
|
|
: public Cell
|
|
, public Weakable<Shape> {
|
|
JS_CELL(Shape, Cell);
|
|
JS_DECLARE_ALLOCATOR(Shape);
|
|
|
|
public:
|
|
virtual ~Shape() override = default;
|
|
|
|
enum class TransitionType : u8 {
|
|
Invalid,
|
|
Put,
|
|
Configure,
|
|
Prototype,
|
|
Delete,
|
|
CacheableDictionary,
|
|
UncacheableDictionary,
|
|
};
|
|
|
|
Shape* create_put_transition(StringOrSymbol const&, PropertyAttributes attributes);
|
|
Shape* create_configure_transition(StringOrSymbol const&, PropertyAttributes attributes);
|
|
Shape* create_prototype_transition(Object* new_prototype);
|
|
[[nodiscard]] NonnullGCPtr<Shape> create_delete_transition(StringOrSymbol const&);
|
|
[[nodiscard]] NonnullGCPtr<Shape> create_cacheable_dictionary_transition();
|
|
[[nodiscard]] NonnullGCPtr<Shape> create_uncacheable_dictionary_transition();
|
|
|
|
void add_property_without_transition(StringOrSymbol const&, PropertyAttributes);
|
|
void add_property_without_transition(PropertyKey const&, PropertyAttributes);
|
|
|
|
void remove_property_without_transition(StringOrSymbol const&, u32 offset);
|
|
void set_property_attributes_without_transition(StringOrSymbol const&, PropertyAttributes);
|
|
|
|
[[nodiscard]] bool is_cacheable() const { return m_cacheable; }
|
|
[[nodiscard]] bool is_dictionary() const { return m_dictionary; }
|
|
[[nodiscard]] bool is_cacheable_dictionary() const { return m_dictionary && m_cacheable; }
|
|
[[nodiscard]] bool is_uncacheable_dictionary() const { return m_dictionary && !m_cacheable; }
|
|
|
|
Realm& realm() const { return m_realm; }
|
|
|
|
Object* prototype() { return m_prototype; }
|
|
Object const* prototype() const { return m_prototype; }
|
|
|
|
Optional<PropertyMetadata> lookup(StringOrSymbol const&) const;
|
|
OrderedHashMap<StringOrSymbol, PropertyMetadata> const& property_table() const;
|
|
u32 property_count() const { return m_property_count; }
|
|
|
|
struct Property {
|
|
StringOrSymbol key;
|
|
PropertyMetadata value;
|
|
};
|
|
|
|
void set_prototype_without_transition(Object* new_prototype) { m_prototype = new_prototype; }
|
|
|
|
private:
|
|
explicit Shape(Realm&);
|
|
Shape(Shape& previous_shape, StringOrSymbol const& property_key, PropertyAttributes attributes, TransitionType);
|
|
Shape(Shape& previous_shape, StringOrSymbol const& property_key, TransitionType);
|
|
Shape(Shape& previous_shape, Object* new_prototype);
|
|
|
|
virtual void visit_edges(Visitor&) override;
|
|
|
|
Shape* get_or_prune_cached_forward_transition(TransitionKey const&);
|
|
Shape* get_or_prune_cached_prototype_transition(Object* prototype);
|
|
[[nodiscard]] GCPtr<Shape> get_or_prune_cached_delete_transition(StringOrSymbol const&);
|
|
|
|
void ensure_property_table() const;
|
|
|
|
NonnullGCPtr<Realm> m_realm;
|
|
|
|
mutable OwnPtr<OrderedHashMap<StringOrSymbol, PropertyMetadata>> m_property_table;
|
|
|
|
OwnPtr<HashMap<TransitionKey, WeakPtr<Shape>>> m_forward_transitions;
|
|
OwnPtr<HashMap<GCPtr<Object>, WeakPtr<Shape>>> m_prototype_transitions;
|
|
OwnPtr<HashMap<StringOrSymbol, WeakPtr<Shape>>> m_delete_transitions;
|
|
GCPtr<Shape> m_previous;
|
|
StringOrSymbol m_property_key;
|
|
GCPtr<Object> m_prototype;
|
|
u32 m_property_count { 0 };
|
|
|
|
PropertyAttributes m_attributes { 0 };
|
|
TransitionType m_transition_type { TransitionType::Invalid };
|
|
|
|
bool m_dictionary { false };
|
|
bool m_cacheable { true };
|
|
};
|
|
|
|
}
|
|
|
|
template<>
|
|
struct AK::Traits<JS::TransitionKey> : public DefaultTraits<JS::TransitionKey> {
|
|
static unsigned hash(const JS::TransitionKey& key)
|
|
{
|
|
return pair_int_hash(key.attributes.bits(), Traits<JS::StringOrSymbol>::hash(key.property_key));
|
|
}
|
|
};
|