message: eliminate copy
diff: @@ -634,7 +634,7 @@ public:
  bool handleAttributes(llvm::Argument &arg) {
  auto attrs = arg.getParent()->getAttributes()
  .getParamAttributes(arg.getArgNo());
  - for (auto attr : attrs) {
  + for (auto &attr : attrs) {
  switch (attr.getKindAsEnum()) {
  default:
  *out << "ERROR: Unsupported attribute: " << attr.getAsString() << '\n';
  