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LibJS: Instantiate primitive array expressions using a single operation

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This will not meaningfully affect short array literals, but it does
give us a bit of extra perf when evaluating huge array expressions like
in Kraken/imaging-darkroom.js
This commit is contained in:
Idan Horowitz 2023-11-17 22:07:23 +02:00 • committed by Andreas Kling
parent 5e3a799e97
commit f19349e1b6
7 changed files with 92 additions and 6 deletions
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13
Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
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@ -1012,6 +1012,19 @@ Bytecode::CodeGenerationErrorOr<void> ArrayExpression::generate_bytecode(Bytecod
return {};
}
if (all_of(m_elements, [](auto element) { return !element || is<PrimitiveLiteral>(*element); })) {
// If all elements are constant primitives, we can just emit a single instruction to initialize the array,
// instead of emitting instructions to manually evaluate them one-by-one
auto values = MUST(FixedArray<Value>::create(m_elements.size()));
for (auto i = 0u; i < m_elements.size(); ++i) {
if (!m_elements[i])
continue;
values[i] = static_cast<PrimitiveLiteral const&>(*m_elements[i]).value();
}
generator.emit<Bytecode::Op::NewPrimitiveArray>(move(values));
return {};
}
auto first_spread = find_if(m_elements.begin(), m_elements.end(), [](auto el) { return el && is<SpreadExpression>(*el); });
Bytecode::Register args_start_reg { 0 };