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LibJS/Bytecode: Create global variables before setting them

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This allows them to be accessed before assignment, and also prevents
throwing in strict mode as we are trying to set a non-existent
variable.
This commit is contained in:
Luke Wilde 2022-07-17 19:06:44 +01:00 • committed by Linus Groh
parent 12e3abc9e7
commit c55a4c7f30
3 changed files with 25 additions and 13 deletions
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13
Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
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@ -181,9 +181,7 @@ Bytecode::CodeGenerationErrorOr<void> ScopeNode::generate_bytecode(Bytecode::Gen
// ii. If declaredFunctionOrVarNames does not contain F, then
if (!declared_function_names.contains(function_name) && !declared_var_names.contains(function_name)) {
// i. Perform ? env.CreateGlobalVarBinding(F, false).
generator.emit<Bytecode::Op::CreateVariable>(index, Bytecode::Op::EnvironmentMode::Var, false);
generator.emit<Bytecode::Op::LoadImmediate>(js_undefined());
generator.emit<Bytecode::Op::SetVariable>(index, Bytecode::Op::SetVariable::InitializationMode::Initialize, Bytecode::Op::EnvironmentMode::Var);
generator.emit<Bytecode::Op::CreateVariable>(index, Bytecode::Op::EnvironmentMode::Var, false, true);
// ii. Append F to declaredFunctionOrVarNames.
declared_function_names.set(function_name);
@ -238,9 +236,12 @@ Bytecode::CodeGenerationErrorOr<void> ScopeNode::generate_bytecode(Bytecode::Gen
}
// 17. For each String vn of declaredVarNames, do
// a. Perform ? env.CreateGlobalVarBinding(vn, false).
for (auto& var_name : declared_var_names)
generator.register_binding(generator.intern_identifier(var_name), Bytecode::Generator::BindingMode::Var);
for (auto& var_name : declared_var_names) {
// a. Perform ? env.CreateGlobalVarBinding(vn, false).
auto index = generator.intern_identifier(var_name);
generator.register_binding(index, Bytecode::Generator::BindingMode::Var);
generator.emit<Bytecode::Op::CreateVariable>(index, Bytecode::Op::EnvironmentMode::Var, false, true);
}
} else {
// Perform the steps of FunctionDeclarationInstantiation.
generator.begin_variable_scope(Bytecode::Generator::BindingMode::Var, Bytecode::Generator::SurroundingScopeKind::Function);