Reply To: Metadata

Actually NaR and None together are impossible. NaRs carry a “kind” indicating the nature of the initial problem, and a None is encoded as a flavor of NaR. That way the None/NaR propagation logic in the speculable FUs doesn’t have to test, and only the non-speculable ops (like store) need to care. As often happens, at the program level these are different but at the machine level they are blended to optimize the hardware.