LibJS/JIT: Compile the ConcatString bytecode instruction

Userland/Libraries/LibJS/Bytecode/Op.h

@@ -362,6 +362,8 @@ public:
     ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const;
     DeprecatedString to_deprecated_string_impl(Bytecode::Executable const&) const;
 
+    Register lhs() const { return m_lhs; }
+
 private:
     Register m_lhs;
 };

Userland/Libraries/LibJS/JIT/Compiler.cpp

@@ -1027,6 +1027,21 @@ void Compiler::compile_leave_lexical_environment(Bytecode::Op::LeaveLexicalEnvir
     native_call((void*)cxx_leave_lexical_environment);
 }
 
+static Value cxx_concat_string(VM& vm, Value lhs, Value rhs)
+{
+    auto string = TRY_OR_SET_EXCEPTION(rhs.to_primitive_string(vm));
+    return PrimitiveString::create(vm, lhs.as_string(), string);
+}
+
+void Compiler::compile_concat_string(Bytecode::Op::ConcatString const& op)
+{
+    load_vm_register(ARG1, op.lhs());
+    load_vm_register(ARG2, Bytecode::Register::accumulator());
+    native_call((void*)cxx_concat_string);
+    store_vm_register(op.lhs(), RET);
+    check_exception();
+}
+
 void Compiler::jump_to_exit()
 {
     m_assembler.jump(m_exit_label);
@@ -1190,6 +1205,9 @@ OwnPtr<NativeExecutable> Compiler::compile(Bytecode::Executable& bytecode_execut
             case Bytecode::Instruction::Type::ContinuePendingUnwind:
                 compiler.compile_continue_pending_unwind(static_cast<Bytecode::Op::ContinuePendingUnwind const&>(op));
                 break;
+            case Bytecode::Instruction::Type::ConcatString:
+                compiler.compile_concat_string(static_cast<Bytecode::Op::ConcatString const&>(op));
+                break;
 
 #    define DO_COMPILE_COMMON_BINARY_OP(TitleCaseName, snake_case_name)                          \
     case Bytecode::Instruction::Type::TitleCaseName:                                             \

Userland/Libraries/LibJS/JIT/Compiler.h

@@ -115,6 +115,7 @@ private:
     void compile_typeof_variable(Bytecode::Op::TypeofVariable const&);
     void compile_set_variable(Bytecode::Op::SetVariable const&);
     void compile_continue_pending_unwind(Bytecode::Op::ContinuePendingUnwind const&);
+    void compile_concat_string(Bytecode::Op::ConcatString const&);
 
     void store_vm_register(Bytecode::Register, Assembler::Reg);
     void load_vm_register(Assembler::Reg, Bytecode::Register);