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LibJS/Bytecode: Implement initial support for super member expressions

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Luke Wilde 2023-05-15 18:45:16 +01:00 • committed by Andreas Kling
parent 00493687f2
commit b15128c45b
5 changed files with 137 additions and 31 deletions
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65
Userland/Libraries/LibJS/Bytecode/Generator.cpp
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@ -151,22 +151,61 @@ CodeGenerationErrorOr<void> Generator::emit_load_from_reference(JS::ASTNode cons
}
if (is<MemberExpression>(node)) {
auto& expression = static_cast<MemberExpression const&>(node);
TRY(expression.object().generate_bytecode(*this));
if (expression.is_computed()) {
auto object_reg = allocate_register();
emit<Bytecode::Op::Store>(object_reg);
// https://tc39.es/ecma262/#sec-super-keyword-runtime-semantics-evaluation
if (is<SuperExpression>(expression.object())) {
// 1. Let env be GetThisEnvironment().
// 2. Let actualThis be ? env.GetThisBinding().
// NOTE: Whilst this isn't used, it's still observable (e.g. it throws if super() hasn't been called)
emit<Bytecode::Op::ResolveThisBinding>();
TRY(expression.property().generate_bytecode(*this));
emit<Bytecode::Op::GetByValue>(object_reg);
} else if (expression.property().is_identifier()) {
auto identifier_table_ref = intern_identifier(verify_cast<Identifier>(expression.property()).string());
emit<Bytecode::Op::GetById>(identifier_table_ref);
Optional<Bytecode::Register> computed_property_value_register;
if (expression.is_computed()) {
// SuperProperty : super [ Expression ]
// 3. Let propertyNameReference be ? Evaluation of Expression.
// 4. Let propertyNameValue be ? GetValue(propertyNameReference).
TRY(expression.property().generate_bytecode(*this));
computed_property_value_register = allocate_register();
emit<Bytecode::Op::Store>(*computed_property_value_register);
}
// 5/7. Return ? MakeSuperPropertyReference(actualThis, propertyKey, strict).
// https://tc39.es/ecma262/#sec-makesuperpropertyreference
// 1. Let env be GetThisEnvironment().
// 2. Assert: env.HasSuperBinding() is true.
// 3. Let baseValue be ? env.GetSuperBase().
emit<Bytecode::Op::ResolveSuperBase>();
// 4. Return the Reference Record { [[Base]]: baseValue, [[ReferencedName]]: propertyKey, [[Strict]]: strict, [[ThisValue]]: actualThis }.
if (computed_property_value_register.has_value()) {
// 5. Let propertyKey be ? ToPropertyKey(propertyNameValue).
// FIXME: This does ToPropertyKey out of order, which is observable by Symbol.toPrimitive!
emit<Bytecode::Op::GetByValue>(*computed_property_value_register);
} else {
// 3. Let propertyKey be StringValue of IdentifierName.
auto identifier_table_ref = intern_identifier(verify_cast<Identifier>(expression.property()).string());
emit<Bytecode::Op::GetById>(identifier_table_ref);
}
} else {
return CodeGenerationError {
&expression,
"Unimplemented non-computed member expression"sv
};
TRY(expression.object().generate_bytecode(*this));
if (expression.is_computed()) {
auto object_reg = allocate_register();
emit<Bytecode::Op::Store>(object_reg);
TRY(expression.property().generate_bytecode(*this));
emit<Bytecode::Op::GetByValue>(object_reg);
} else if (expression.property().is_identifier()) {
auto identifier_table_ref = intern_identifier(verify_cast<Identifier>(expression.property()).string());
emit<Bytecode::Op::GetById>(identifier_table_ref);
} else {
return CodeGenerationError {
&expression,
"Unimplemented non-computed member expression"sv
};
}
}
return {};
}