Re: use ARM intrinsics in pg_lfind32() where available

On Fri, Aug 19, 2022 at 02:26:02PM -0700, Andres Freund wrote:
> Are you sure there's not an appropriate define for us to use here instead of a
> configure test? E.g.
> 
> echo|cc -dM -P -E -|grep -iE 'arm|aarch'
> ...
> #define __AARCH64_SIMD__ 1
> ...
> #define __ARM_NEON 1
> #define __ARM_NEON_FP 0xE
> #define __ARM_NEON__ 1
> ..
> 
> I strikes me as non-scalable to explicitly test all the simd instructions we'd
> use.

Thanks for the pointer.  GCC, Clang, and the Arm compiler all seem to
define __ARM_NEON, so here is a patch that uses that instead.

-- 
Nathan Bossart
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