On Fri, 13 Aug 2021 at 01:28, David Rowley <dgrowle...@gmail.com> wrote: > > On Fri, 13 Aug 2021 at 01:11, Alvaro Herrera <alvhe...@alvh.no-ip.org> wrote: > > So when on MSVC, you don't have to check CPUID for support? > > That still needs to be checked in MSVC and as far as I can see it is > being properly checked.
Something there that might cause confusion is we do a configure check to see if popcntq works and define HAVE_X86_64_POPCNTQ if it does. I'm still a bit confused at why we bother doing that. Surely it just means that if the build machine does not have popcntq that we'll always use pg_popcount64_slow, regardless if the machine that's actually running the code has popcntq. Maybe you saw that there's no such equivalent test when we set HAVE_X86_64_POPCNTQ for MSVC on x86_64. The reason for that is that we do the run-time test using cpuid. David
