> On that note, is it necessary to also check for avx512f? At the moment, we > are assuming that's supported if the other AVX-512 instructions are available.
No, it's not needed. There are no CPU's with avx512bw/avx512popcnt without avx512f. Unfortunately though, avx512popcnt does not mean avx512bw (I think the deprecated Xeon Phi processors falls in this category) which is why we need both.
