message: Return "argX" for BlockArgument in OpOrArgLocNameMapper::GetName.
  This is for printing better debugging information.
diff: @@ -168,6 +168,10 @@ std::string OpOrArgLocNameMapper::GetName(OpOrVal op_or_val) {
  result.getResultNumber());
  return std::string(result.getOwner()->getName().getStringRef());
  }
  + // Use the ASM syntax for BloackArgument
  + if (auto arg = val.dyn_cast<mlir::BlockArgument>()) {
  + return "arg" + std::to_string(arg.getArgNumber());
  + }
  return "";
  }
  