Re: pgsql: Fix compiler builtin usage in new pg_bitutils.c

On 2019-Feb-15, Tom Lane wrote:

> Meh.  I don't see why this entire function should exist if there
> is nothing for it to do.  I'm inclined to think that somewhere
> there needs to be a symbol NEED_POPCOUNT_CHOOSING that is only
> enabled if we have all three of HAVE__BUILTIN_POPCOUNT, nonempty
> CFLAGS_POPCOUNT, and HAVE__GET_CPUID || HAVE__CPUID.  Possibly
> we should gate building of pg_bitutils_hwpopcnt.c that way too?
> Not much point in building that file if we have no way to figure
> out when to use it.

I'm done with this stuff.  Anybody feel free to run with it, but for a
barely noticeable performance improvement it's not going to be me.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
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