> Well, I suspect the AVX-512 version will pretty much always need the runtime > check given that its not available on a lot of newer hardware and requires a > bunch of extra runtime checks (see pg_popcount_avx512.c). But it might be > worth doing for PCLMUL. Otherwise, I think we'd have to leave out the PCLMUL > optimizations if built with -msse4.2 -mpclmul because we don't want to regress > existing -msse4.2 users with a runtime check.
Sounds good to me. Although, users building with just -msse4.2 will now encounter an an additional pclmul runtime check. That would be a regression unless they update to building with both -msse4.2 and -mpclmul. Raghuveer
