cf6792ec40
Since we can't rely on shape identity (i.e its pointer address) for unique shapes, give them a serial number that increments whenever a mutation occurs. Inline caches can then compare this serial number against what they have seen before.
126 lines
3.9 KiB
C++
126 lines
3.9 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);
|
|
|
|
public:
|
|
virtual ~Shape() override = default;
|
|
|
|
enum class TransitionType {
|
|
Invalid,
|
|
Put,
|
|
Configure,
|
|
Prototype,
|
|
};
|
|
|
|
Shape* create_put_transition(StringOrSymbol const&, PropertyAttributes attributes);
|
|
Shape* create_configure_transition(StringOrSymbol const&, PropertyAttributes attributes);
|
|
Shape* create_prototype_transition(Object* new_prototype);
|
|
|
|
void add_property_without_transition(StringOrSymbol const&, PropertyAttributes);
|
|
void add_property_without_transition(PropertyKey const&, PropertyAttributes);
|
|
|
|
bool is_unique() const { return m_unique; }
|
|
Shape* create_unique_clone() const;
|
|
|
|
Realm& realm() const { return m_realm; }
|
|
|
|
Object* prototype() { return m_prototype; }
|
|
Object const* prototype() const { return m_prototype; }
|
|
|
|
Optional<PropertyMetadata> lookup(StringOrSymbol const&) const;
|
|
HashMap<StringOrSymbol, PropertyMetadata> const& property_table() const;
|
|
u32 property_count() const { return m_property_count; }
|
|
|
|
struct Property {
|
|
StringOrSymbol key;
|
|
PropertyMetadata value;
|
|
};
|
|
|
|
Vector<Property> property_table_ordered() const;
|
|
|
|
void set_prototype_without_transition(Object* new_prototype) { m_prototype = new_prototype; }
|
|
|
|
void remove_property_from_unique_shape(StringOrSymbol const&, size_t offset);
|
|
void add_property_to_unique_shape(StringOrSymbol const&, PropertyAttributes attributes);
|
|
void reconfigure_property_in_unique_shape(StringOrSymbol const& property_key, PropertyAttributes attributes);
|
|
|
|
[[nodiscard]] u64 unique_shape_serial_number() const { return m_unique_shape_serial_number; }
|
|
|
|
private:
|
|
explicit Shape(Realm&);
|
|
Shape(Shape& previous_shape, StringOrSymbol const& property_key, PropertyAttributes attributes, 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);
|
|
|
|
void ensure_property_table() const;
|
|
|
|
NonnullGCPtr<Realm> m_realm;
|
|
|
|
mutable OwnPtr<HashMap<StringOrSymbol, PropertyMetadata>> m_property_table;
|
|
|
|
OwnPtr<HashMap<TransitionKey, WeakPtr<Shape>>> m_forward_transitions;
|
|
OwnPtr<HashMap<GCPtr<Object>, WeakPtr<Shape>>> m_prototype_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 : 6 { TransitionType::Invalid };
|
|
bool m_unique : 1 { false };
|
|
|
|
// Since unique shapes never change identity, inline caches use this incrementing serial number
|
|
// to know whether its property table has been modified since last time we checked.
|
|
u64 m_unique_shape_serial_number { 0 };
|
|
};
|
|
|
|
}
|
|
|
|
template<>
|
|
struct AK::Traits<JS::TransitionKey> : public GenericTraits<JS::TransitionKey> {
|
|
static unsigned hash(const JS::TransitionKey& key)
|
|
{
|
|
return pair_int_hash(key.attributes.bits(), Traits<JS::StringOrSymbol>::hash(key.property_key));
|
|
}
|
|
};
|