8ff16c1b57
We already had fast access to own properties via shape-based IC. This patch extends the mechanism to properties on the prototype chain, using the "validity cell" technique from V8. - Prototype objects now have unique shape - Each prototype has an associated PrototypeChainValidity - When a prototype shape is mutated, every prototype shape "below" it in any prototype chain is invalidated. - Invalidation happens by marking the validity object as invalid, and then replacing it with a new validity object. - Property caches keep a pointer to the last seen valid validity. If there is no validity, or the validity is invalid, the cache misses and gets repopulated. This is very helpful when using JavaScript to access DOM objects, as we frequently have to traverse 4+ prototype objects before finding the property we're interested in on e.g EventTarget or Node.
92 lines
2.6 KiB
C++
92 lines
2.6 KiB
C++
/*
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* Copyright (c) 2021-2024, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/DeprecatedFlyString.h>
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#include <AK/HashMap.h>
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#include <AK/NonnullOwnPtr.h>
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#include <AK/OwnPtr.h>
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#include <AK/WeakPtr.h>
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#include <LibJS/Bytecode/IdentifierTable.h>
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#include <LibJS/Bytecode/Label.h>
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#include <LibJS/Bytecode/StringTable.h>
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#include <LibJS/Forward.h>
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#include <LibJS/Heap/Cell.h>
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#include <LibJS/Heap/CellAllocator.h>
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#include <LibJS/Runtime/EnvironmentCoordinate.h>
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namespace JS::Bytecode {
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struct PropertyLookupCache {
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WeakPtr<Shape> shape;
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Optional<u32> property_offset;
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WeakPtr<Object> prototype;
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WeakPtr<PrototypeChainValidity> prototype_chain_validity;
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};
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struct GlobalVariableCache : public PropertyLookupCache {
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u64 environment_serial_number { 0 };
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};
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using EnvironmentVariableCache = Optional<EnvironmentCoordinate>;
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struct SourceRecord {
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u32 source_start_offset {};
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u32 source_end_offset {};
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};
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class Executable final : public Cell {
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JS_CELL(Executable, Cell);
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JS_DECLARE_ALLOCATOR(Executable);
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public:
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Executable(
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NonnullOwnPtr<IdentifierTable>,
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NonnullOwnPtr<StringTable>,
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NonnullOwnPtr<RegexTable>,
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Vector<Value> constants,
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NonnullRefPtr<SourceCode const>,
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size_t number_of_property_lookup_caches,
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size_t number_of_global_variable_caches,
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size_t number_of_environment_variable_caches,
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size_t number_of_registers,
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Vector<NonnullOwnPtr<BasicBlock>>,
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bool is_strict_mode);
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virtual ~Executable() override;
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DeprecatedFlyString name;
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Vector<PropertyLookupCache> property_lookup_caches;
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Vector<GlobalVariableCache> global_variable_caches;
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Vector<EnvironmentVariableCache> environment_variable_caches;
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Vector<NonnullOwnPtr<BasicBlock>> basic_blocks;
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NonnullOwnPtr<StringTable> string_table;
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NonnullOwnPtr<IdentifierTable> identifier_table;
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NonnullOwnPtr<RegexTable> regex_table;
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Vector<Value> constants;
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NonnullRefPtr<SourceCode const> source_code;
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size_t number_of_registers { 0 };
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bool is_strict_mode { false };
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ByteString const& get_string(StringTableIndex index) const { return string_table->get(index); }
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DeprecatedFlyString const& get_identifier(IdentifierTableIndex index) const { return identifier_table->get(index); }
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Optional<DeprecatedFlyString const&> get_identifier(Optional<IdentifierTableIndex> const& index) const
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{
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if (!index.has_value())
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return {};
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return get_identifier(*index);
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}
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void dump() const;
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private:
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virtual void visit_edges(Visitor&) override;
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};
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}
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