From 72736f9e93963334a879c4fbc432677138e7d42f Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Mon, 25 Oct 2021 15:17:41 +0200
Subject: [PATCH] LibJS: Generate bytecode for UpdateExpression with
 MemberExpression arg

---
 .../Libraries/LibJS/Bytecode/ASTCodegen.cpp   | 34 ++++++++-----------
 1 file changed, 14 insertions(+), 20 deletions(-)

diff --git a/Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp b/Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
index b55a79dddd1..c9c89557d11 100644
--- a/Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
+++ b/Userland/Libraries/LibJS/Bytecode/ASTCodegen.cpp
@@ -1134,29 +1134,23 @@ void TaggedTemplateLiteral::generate_bytecode(Bytecode::Generator& generator) co
 
 void UpdateExpression::generate_bytecode(Bytecode::Generator& generator) const
 {
-    if (is<Identifier>(*m_argument)) {
-        auto& identifier = static_cast<Identifier const&>(*m_argument);
-        generator.emit<Bytecode::Op::GetVariable>(generator.intern_identifier(identifier.string()));
+    generator.emit_load_from_reference(*m_argument);
 
-        Optional<Bytecode::Register> previous_value_for_postfix_reg;
-        if (!m_prefixed) {
-            previous_value_for_postfix_reg = generator.allocate_register();
-            generator.emit<Bytecode::Op::Store>(*previous_value_for_postfix_reg);
-        }
-
-        if (m_op == UpdateOp::Increment)
-            generator.emit<Bytecode::Op::Increment>();
-        else
-            generator.emit<Bytecode::Op::Decrement>();
-
-        generator.emit<Bytecode::Op::SetVariable>(generator.intern_identifier(identifier.string()));
-
-        if (!m_prefixed)
-            generator.emit<Bytecode::Op::Load>(*previous_value_for_postfix_reg);
-        return;
+    Optional<Bytecode::Register> previous_value_for_postfix_reg;
+    if (!m_prefixed) {
+        previous_value_for_postfix_reg = generator.allocate_register();
+        generator.emit<Bytecode::Op::Store>(*previous_value_for_postfix_reg);
     }
 
-    TODO();
+    if (m_op == UpdateOp::Increment)
+        generator.emit<Bytecode::Op::Increment>();
+    else
+        generator.emit<Bytecode::Op::Decrement>();
+
+    generator.emit_store_to_reference(*m_argument);
+
+    if (!m_prefixed)
+        generator.emit<Bytecode::Op::Load>(*previous_value_for_postfix_reg);
 }
 
 void ThrowStatement::generate_bytecode(Bytecode::Generator& generator) const