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LibJS/Bytecode: Don't emit GetGlobal undefined

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We know that `undefined` in the global scope is always the proper
undefined value. This commit takes advantage of that by simply emitting
a constant undefined value instead.

Unfortunately we can't be so sure in other scopes.
This commit is contained in:
Andreas Kling 2024-05-09 15:21:24 +02:00 • committed by Alexander Kalenik
commit caf2e675bf
Notes: sideshowbarker 2024-07-17 08:35:21 +09:00
1 changed files with 4 additions and 0 deletions
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4
Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
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@ -382,6 +382,10 @@ Bytecode::CodeGenerationErrorOr<Optional<ScopedOperand>> Identifier::generate_by
return local;
}
if (is_global() && m_string == "undefined"sv) {
return generator.add_constant(js_undefined());
}
auto dst = choose_dst(generator, preferred_dst);
if (is_global()) {
generator.emit<Bytecode::Op::GetGlobal>(dst, generator.intern_identifier(m_string), generator.next_global_variable_cache());