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LibJS: Optimize array destructuring assignment for builtin iterators

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...by avoiding `{ value, done }` iterator result value allocation. This
change applies the same otimization 81b6a11 added for `for..in` and
`for..of`.

Makes following micro benchmark go 22% faster on my computer:
```js
function f() {
    const arr = [];
    for (let i = 0; i < 10_000_000; i++) {
        arr.push([i]);
    }
    let sum = 0;
    for (let [i] of arr) {
        sum += i;
    }
}

f();
```
This commit is contained in:
Aliaksandr Kalenik 2025-05-01 16:05:24 +03:00 • committed by Alexander Kalenik
parent 295b78f7d3
commit 60bd5012fe
Notes: github-actions[bot] 2025-05-01 13:58:54 +00:00
4 changed files with 11 additions and 15 deletions
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8
Libraries/LibJS/Bytecode/Interpreter.cpp
View file

@ -612,7 +612,6 @@ FLATTEN_ON_CLANG void Interpreter::run_bytecode(size_t entry_point)
HANDLE_INSTRUCTION_WITHOUT_EXCEPTION_CHECK(Dump);
HANDLE_INSTRUCTION(EnterObjectEnvironment);
HANDLE_INSTRUCTION(Exp);
HANDLE_INSTRUCTION(ForOfNext);
HANDLE_INSTRUCTION(GetById);
HANDLE_INSTRUCTION(GetByIdWithThis);
HANDLE_INSTRUCTION(GetByValue);
@ -642,6 +641,7 @@ FLATTEN_ON_CLANG void Interpreter::run_bytecode(size_t entry_point)
HANDLE_INSTRUCTION(InstanceOf);
HANDLE_INSTRUCTION(IteratorClose);
HANDLE_INSTRUCTION(IteratorNext);
HANDLE_INSTRUCTION(IteratorNextUnpack);
HANDLE_INSTRUCTION(IteratorToArray);
HANDLE_INSTRUCTION_WITHOUT_EXCEPTION_CHECK(LeaveFinally);
HANDLE_INSTRUCTION_WITHOUT_EXCEPTION_CHECK(LeaveLexicalEnvironment);
@ -2982,7 +2982,7 @@ ThrowCompletionOr<void> IteratorNext::execute_impl(Bytecode::Interpreter& interp
return {};
}
ThrowCompletionOr<void> ForOfNext::execute_impl(Bytecode::Interpreter& interpreter) const
ThrowCompletionOr<void> IteratorNextUnpack::execute_impl(Bytecode::Interpreter& interpreter) const
{
auto& vm = interpreter.vm();
auto& iterator_record = static_cast<IteratorRecord&>(interpreter.get(m_iterator_record).as_cell());
@ -3777,9 +3777,9 @@ ByteString IteratorNext::to_byte_string_impl(Executable const& executable) const
format_operand("iterator_record"sv, m_iterator_record, executable));
}
ByteString ForOfNext::to_byte_string_impl(Executable const& executable) const
ByteString IteratorNextUnpack::to_byte_string_impl(Executable const& executable) const
{
return ByteString::formatted("ForOfNext {}, {}, {}",
return ByteString::formatted("IteratorNextUnpack {}, {}, {}",
format_operand("dst_value"sv, m_dst_value, executable),
format_operand("dst_done"sv, m_dst_done, executable),
format_operand("iterator_record"sv, m_iterator_record, executable));