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646457099c
With this change, `GetIterator` no longer GC-allocates an
`IteratorRecord`. Instead, it stores the iterator record fields in
bytecode registers. This avoids per-iteration allocations in patterns
like: `for (let [x] of array) {}`.
`IteratorRecord` now inherits from `IteratorRecordImpl`, which holds the
iteration state. This allows the existing iteration helpers
(`iterator_next()`, `iterator_step()`, etc.) operate on both the
GC-allocated and the register-backed forms.
Microbenchmarks:
1.1x array-destructuring-assignment-rest.js
1.226x array-destructuring-assignment.js
74 lines
1.9 KiB
C++
74 lines
1.9 KiB
C++
/*
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* Copyright (c) 2021, Idan Horowitz <idan.horowitz@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/Array.h>
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#include <LibJS/Runtime/NativeFunction.h>
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#include <LibJS/Runtime/SetIterator.h>
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namespace JS {
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GC_DEFINE_ALLOCATOR(SetIterator);
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GC::Ref<SetIterator> SetIterator::create(Realm& realm, Set& set, Object::PropertyKind iteration_kind)
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{
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return realm.create<SetIterator>(set, iteration_kind, realm.intrinsics().set_iterator_prototype());
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}
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SetIterator::SetIterator(Set& set, Object::PropertyKind iteration_kind, Object& prototype)
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: Object(ConstructWithPrototypeTag::Tag, prototype)
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, m_set(set)
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, m_iteration_kind(iteration_kind)
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, m_iterator(static_cast<Set const&>(set).begin())
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{
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}
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void SetIterator::visit_edges(Cell::Visitor& visitor)
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{
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Base::visit_edges(visitor);
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visitor.visit(m_set);
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}
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BuiltinIterator* SetIterator::as_builtin_iterator_if_next_is_not_redefined(Value next_method)
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{
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if (next_method.is_object()) {
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auto const& next_function = next_method.as_object();
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if (next_function.is_native_function()) {
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auto const& native_function = static_cast<NativeFunction const&>(next_function);
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if (native_function.is_set_prototype_next_builtin())
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return this;
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}
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}
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return nullptr;
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}
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ThrowCompletionOr<void> SetIterator::next(VM& vm, bool& done, Value& value)
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{
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if (m_done) {
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done = true;
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value = js_undefined();
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return {};
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}
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if (m_iterator == m_set->end()) {
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m_done = true;
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done = true;
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value = js_undefined();
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return {};
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}
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VERIFY(m_iteration_kind != Object::PropertyKind::Key);
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value = (*m_iterator).key;
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++m_iterator;
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if (m_iteration_kind == Object::PropertyKind::Value) {
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return {};
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}
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value = Array::create_from(*vm.current_realm(), { value, value });
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return {};
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}
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}
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