This is clean up after adding argmemonly attribute.
This change teaches TableGen to emit argmemonly attribute when intrinsics are marked with ReadArgMem or ReadWriteArgMem flags. This will allow to remove GET_INTRINSIC_MODREF_BEHAVIOR in a follow up patches.
The fact you're having to add argument sets containing anything other than the attributes which were there before and your argmemonly attribute is highly suspicious. I suspect this is the symptom of a bug.