4699c81fc1
This patch makes IteratorRecord an Object. Although it's not exposed to
author code, this does allow us to store it in a VM register.
Now that we can store it in a VM register, we don't need to convert it
back and forth between IteratorRecord and Object when accessing it from
bytecode.
The big win here is avoiding 3 [[Get]] accesses on every iteration step
of for..of loops. There are also a bunch of smaller efficiencies gained.
20% speed-up on this microbenchmark:
function go(a) {
for (const p of a) {
}
}
const a = [];
a.length = 1_000_000;
go(a);
49 lines
1.5 KiB
C++
49 lines
1.5 KiB
C++
/*
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* Copyright (c) 2023, Tim Flynn <trflynn89@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 <LibJS/Runtime/Completion.h>
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#include <LibJS/Runtime/GeneratorObject.h>
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#include <LibJS/Runtime/Iterator.h>
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#include <LibJS/Runtime/Object.h>
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#include <LibJS/SafeFunction.h>
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namespace JS {
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class IteratorHelper final : public GeneratorObject {
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JS_OBJECT(IteratorHelper, GeneratorObject);
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JS_DECLARE_ALLOCATOR(IteratorHelper);
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public:
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using Closure = JS::SafeFunction<ThrowCompletionOr<Value>(VM&, IteratorHelper&)>;
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using AbruptClosure = JS::SafeFunction<ThrowCompletionOr<Value>(VM&, IteratorHelper&, Completion const&)>;
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static ThrowCompletionOr<NonnullGCPtr<IteratorHelper>> create(Realm&, NonnullGCPtr<IteratorRecord>, Closure, Optional<AbruptClosure> = {});
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IteratorRecord const& underlying_iterator() const { return m_underlying_iterator; }
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size_t counter() const { return m_counter; }
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void increment_counter() { ++m_counter; }
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Value result(Value);
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ThrowCompletionOr<Value> close_result(VM&, Completion);
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private:
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IteratorHelper(Realm&, Object& prototype, NonnullGCPtr<IteratorRecord>, Closure, Optional<AbruptClosure>);
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virtual void visit_edges(Visitor&) override;
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virtual ThrowCompletionOr<Value> execute(VM&, JS::Completion const& completion) override;
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NonnullGCPtr<IteratorRecord> m_underlying_iterator; // [[UnderlyingIterator]]
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Closure m_closure;
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Optional<AbruptClosure> m_abrupt_closure;
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size_t m_counter { 0 };
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bool m_done { false };
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};
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}
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