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);
36 lines
1.1 KiB
C++
36 lines
1.1 KiB
C++
/*
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* Copyright (c) 2021, David Tuin <davidot@serenityos.org>
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* Copyright (c) 2022, Linus Groh <linusg@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/Iterator.h>
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#include <LibJS/Runtime/Object.h>
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namespace JS {
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// 27.1.4.3 Properties of Async-from-Sync Iterator Instances, https://tc39.es/ecma262/#sec-properties-of-async-from-sync-iterator-instances
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class AsyncFromSyncIterator final : public Object {
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JS_OBJECT(AsyncFromSyncIterator, Object);
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JS_DECLARE_ALLOCATOR(AsyncFromSyncIterator);
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public:
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static NonnullGCPtr<AsyncFromSyncIterator> create(Realm&, NonnullGCPtr<IteratorRecord> sync_iterator_record);
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virtual ~AsyncFromSyncIterator() override = default;
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void visit_edges(Visitor& visitor) override;
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IteratorRecord& sync_iterator_record() { return m_sync_iterator_record; }
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IteratorRecord const& sync_iterator_record() const { return m_sync_iterator_record; }
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private:
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AsyncFromSyncIterator(Realm&, NonnullGCPtr<IteratorRecord> sync_iterator_record);
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NonnullGCPtr<IteratorRecord> m_sync_iterator_record; // [[SyncIteratorRecord]]
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};
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}
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