It actually does detect it using ifdef [0] but uses cmake stuff to avoid passing "-mavx512" kind of flags to the compiler [1].

[0] https://github.com/esutcu/planb-lpm/blob/748d19d5fbd945cefa3...

[1] https://github.com/esutcu/planb-lpm/blob/748d19d5fbd945cefa3...