LibJS: Remove direct argument loading since it was buggy

The parser doesn't always track lexical scopes correctly, so let's not
rely on that for direct argument loading.

This reverts the LoadArguments bytecode instruction as well. We can
bring these things back when the parser can reliably tell us that
a given Identifier is indeed a function argument.

Userland/Libraries/LibJS/AST.cpp

@@ -665,8 +665,6 @@ Reference Expression::to_reference(Interpreter&, GlobalObject&) const
 
 Reference Identifier::to_reference(Interpreter& interpreter, GlobalObject&) const
 {
-    if (m_argument_index.has_value())
-        return Reference(Reference::CallFrameArgument, m_argument_index.value(), string());
     return interpreter.vm().get_reference(string());
 }
 
@@ -1315,9 +1313,6 @@ Value Identifier::execute(Interpreter& interpreter, GlobalObject& global_object)
 {
     InterpreterNodeScope node_scope { interpreter, *this };
 
-    if (m_argument_index.has_value())
-        return interpreter.vm().argument(m_argument_index.value());
-
     auto value = interpreter.vm().get_variable(string(), global_object);
     if (value.is_empty()) {
         if (!interpreter.exception())
@@ -1330,10 +1325,7 @@ Value Identifier::execute(Interpreter& interpreter, GlobalObject& global_object)
 void Identifier::dump(int indent) const
 {
     print_indent(indent);
-    if (m_argument_index.has_value())
-        outln("Identifier \"{}\" (argument #{})", m_string, m_argument_index.value());
-    else
-        outln("Identifier \"{}\"", m_string);
+    outln("Identifier \"{}\"", m_string);
 }
 
 void SpreadExpression::dump(int indent) const

Userland/Libraries/LibJS/AST.h

@@ -776,15 +776,13 @@ private:
 
 class Identifier final : public Expression {
 public:
-    explicit Identifier(SourceRange source_range, FlyString string, Optional<size_t> argument_index = {})
+    explicit Identifier(SourceRange source_range, FlyString string)
         : Expression(source_range)
         , m_string(move(string))
-        , m_argument_index(move(argument_index))
     {
     }
 
     FlyString const& string() const { return m_string; }
-    Optional<size_t> const& argument_index() const { return m_argument_index; }
 
     virtual Value execute(Interpreter&, GlobalObject&) const override;
     virtual void dump(int indent) const override;
@@ -795,7 +793,6 @@ private:
     virtual bool is_identifier() const override { return true; }
 
     FlyString m_string;
-    Optional<size_t> m_argument_index;
 };
 
 class ClassMethod final : public ASTNode {

Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp

@@ -267,10 +267,7 @@ void RegExpLiteral::generate_bytecode(Bytecode::Generator& generator) const
 
 void Identifier::generate_bytecode(Bytecode::Generator& generator) const
 {
-    if (m_argument_index.has_value())
-        generator.emit<Bytecode::Op::LoadArgument>(m_argument_index.value());
-    else
-        generator.emit<Bytecode::Op::GetVariable>(generator.intern_string(m_string));
+    generator.emit<Bytecode::Op::GetVariable>(generator.intern_string(m_string));
 }
 
 void AssignmentExpression::generate_bytecode(Bytecode::Generator& generator) const

Userland/Libraries/LibJS/Bytecode/Instruction.h

@@ -65,7 +65,6 @@
     O(Decrement)                        \
     O(Throw)                            \
     O(PushDeclarativeEnvironmentRecord) \
-    O(LoadArgument)                     \
     O(EnterUnwindContext)               \
     O(LeaveUnwindContext)               \
     O(ContinuePendingUnwind)            \

Userland/Libraries/LibJS/Bytecode/Op.cpp

@@ -429,11 +429,6 @@ void PutByValue::execute_impl(Bytecode::Interpreter& interpreter) const
     }
 }
 
-void LoadArgument::execute_impl(Bytecode::Interpreter& interpreter) const
-{
-    interpreter.accumulator() = interpreter.vm().argument(m_index);
-}
-
 void GetIterator::execute_impl(Bytecode::Interpreter& interpreter) const
 {
     interpreter.accumulator() = get_iterator(interpreter.global_object(), interpreter.accumulator());
@@ -672,11 +667,6 @@ String PutByValue::to_string_impl(const Bytecode::Executable&) const
     return String::formatted("PutByValue base:{}, property:{}", m_base, m_property);
 }
 
-String LoadArgument::to_string_impl(const Bytecode::Executable&) const
-{
-    return String::formatted("LoadArgument {}", m_index);
-}
-
 String GetIterator::to_string_impl(Executable const&) const
 {
     return "GetIterator";

Userland/Libraries/LibJS/Bytecode/Op.h

@@ -651,22 +651,6 @@ private:
     HashMap<u32, Variable> m_variables;
 };
 
-class LoadArgument final : public Instruction {
-public:
-    explicit LoadArgument(size_t index)
-        : Instruction(Type::LoadArgument)
-        , m_index(index)
-    {
-    }
-
-    void execute_impl(Bytecode::Interpreter&) const;
-    String to_string_impl(Bytecode::Executable const&) const;
-    void replace_references_impl(BasicBlock const&, BasicBlock const&) { }
-
-private:
-    size_t m_index { 0 };
-};
-
 class GetIterator final : public Instruction {
 public:
     GetIterator()

Userland/Libraries/LibJS/Parser.cpp

@@ -659,23 +659,7 @@ Parser::PrimaryExpressionParseResult Parser::parse_primary_expression()
             set_try_parse_arrow_function_expression_failed_at_position(position(), true);
         }
         auto string = consume().value();
-        Optional<size_t> argument_index;
-        if (!m_state.function_parameters.is_empty()) {
-            size_t i = 0;
-            for (auto& parameter : m_state.function_parameters.last()) {
-                parameter.binding.visit(
-                    [&](FlyString const& name) {
-                        if (name == string) {
-                            argument_index = i;
-                        }
-                    },
-                    [&](BindingPattern const&) {
-                    });
-                ++i;
-            }
-        }
-        argument_index = {};
-        return { create_ast_node<Identifier>({ m_state.current_token.filename(), rule_start.position(), position() }, string, argument_index) };
+        return { create_ast_node<Identifier>({ m_state.current_token.filename(), rule_start.position(), position() }, string) };
     }
     case TokenType::NumericLiteral:
         return { create_ast_node<NumericLiteral>({ m_state.current_token.filename(), rule_start.position(), position() }, consume_and_validate_numeric_literal().double_value()) };

Userland/Libraries/LibJS/Runtime/Reference.cpp

@@ -19,11 +19,6 @@ void Reference::put(GlobalObject& global_object, Value value)
         return;
     }
 
-    if (m_call_frame_argument_index.has_value()) {
-        global_object.vm().call_frame().arguments[m_call_frame_argument_index.value()] = value;
-        return;
-    }
-
     if (is_local_variable() || is_global_variable()) {
         if (is_local_variable())
             vm.set_variable(m_name.to_string(), value, global_object);
@@ -73,9 +68,6 @@ Value Reference::get(GlobalObject& global_object)
         return {};
     }
 
-    if (m_call_frame_argument_index.has_value())
-        return global_object.vm().argument(m_call_frame_argument_index.value());
-
     if (is_local_variable() || is_global_variable()) {
         Value value;
         if (is_local_variable())

Userland/Libraries/LibJS/Runtime/Reference.h

@@ -40,15 +40,6 @@ public:
     {
     }
 
-    enum CallFrameArgumentTag { CallFrameArgument };
-    Reference(CallFrameArgumentTag, size_t index, FlyString const& name)
-        : m_base(js_null())
-        , m_name(name)
-        , m_call_frame_argument_index(index)
-        , m_local_variable(true)
-    {
-    }
-
     Value base() const { return m_base; }
     const PropertyName& name() const { return m_name; }
     bool is_strict() const { return m_strict; }
@@ -83,7 +74,6 @@ private:
 
     Value m_base;
     PropertyName m_name;
-    Optional<size_t> m_call_frame_argument_index;
     bool m_strict { false };
     bool m_local_variable { false };
     bool m_global_variable { false };