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4c789ac689
- Create less GC pressure by making each `await` in async function skip
iteration result object allocation.
- Skip uncached `Object::get()` calls to extract `value` and `done` from
the iteration result object.
With this change, following function goes 30% faster on my computer:
```js
(async () => {
const resolved = Promise.resolve();
for (let i = 0; i < 5_000_000; i++) {
await resolved;
}
})();
```
72 lines
2.5 KiB
C++
72 lines
2.5 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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#include <LibJS/Runtime/GlobalObject.h>
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#include <LibJS/Runtime/Iterator.h>
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#include <LibJS/Runtime/IteratorHelper.h>
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#include <LibJS/Runtime/Realm.h>
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namespace JS {
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GC_DEFINE_ALLOCATOR(IteratorHelper);
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ThrowCompletionOr<GC::Ref<IteratorHelper>> IteratorHelper::create(Realm& realm, GC::Ref<IteratorRecord> underlying_iterator, GC::Ref<Closure> closure, GC::Ptr<AbruptClosure> abrupt_closure)
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{
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return realm.create<IteratorHelper>(realm, realm.intrinsics().iterator_helper_prototype(), move(underlying_iterator), closure, abrupt_closure);
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}
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IteratorHelper::IteratorHelper(Realm& realm, Object& prototype, GC::Ref<IteratorRecord> underlying_iterator, GC::Ref<Closure> closure, GC::Ptr<AbruptClosure> abrupt_closure)
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: GeneratorObject(realm, prototype, realm.vm().running_execution_context().copy(), "Iterator Helper"sv)
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, m_underlying_iterator(move(underlying_iterator))
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, m_closure(closure)
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, m_abrupt_closure(abrupt_closure)
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{
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}
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void IteratorHelper::visit_edges(Visitor& visitor)
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{
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Base::visit_edges(visitor);
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visitor.visit(m_underlying_iterator);
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visitor.visit(m_closure);
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visitor.visit(m_abrupt_closure);
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}
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Value IteratorHelper::result(Value value)
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{
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set_generator_state(value.is_undefined() ? GeneratorState::Completed : GeneratorState::SuspendedYield);
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return value;
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}
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ThrowCompletionOr<Value> IteratorHelper::close_result(VM& vm, Completion completion)
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{
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set_generator_state(GeneratorState::Completed);
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return TRY(iterator_close(vm, underlying_iterator(), move(completion)));
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}
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ThrowCompletionOr<GeneratorObject::IterationResult> IteratorHelper::execute(VM& vm, JS::Completion const& completion)
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{
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ScopeGuard guard { [&] { vm.pop_execution_context(); } };
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if (completion.is_abrupt()) {
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if (m_abrupt_closure) {
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auto abrupt_result = TRY(m_abrupt_closure->function()(vm, *this, completion));
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return IterationResult(abrupt_result, true);
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}
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auto close_result = TRY(this->close_result(vm, completion));
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return IterationResult(close_result, true);
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}
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auto result_value = m_closure->function()(vm, *this);
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if (result_value.is_throw_completion()) {
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set_generator_state(GeneratorState::Completed);
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return result_value.throw_completion();
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}
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return IterationResult(result(result_value.release_value()), generator_state() == GeneratorState::Completed);
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}
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}
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