[llvm] r268539 - [AArch64] Use the reciprocal estimation machinery

[Renato Golin via llvm-commits]

On 20 September 2016 at 13:15, Evandro Menezes via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
> Thus, if anything, the discussion should be broader than AArch64.  Until
> that's settled, it's preferable to keep this patch until an universal
> solution is found, IMO.

Hi Evandro,

I agree this needs a wider audience, but the patch is introducing
"isCoreX" which we have extensively discussed is a pattern we want to
be moving away from, not towards. Making it into
"hasFeatureFastReciprocal" won't help either. If you read the
discussion topics I pointed you, this is not just dependent on the
architecture, but on the context.

Rushing this feature in and leaving it there to push artificial
benchmark numbers up (no one else will be building them with
-mcpu=exynos-m1) seems tempting, but we much refrain from specific
code when the behaviour is not deterministic in the overall case.

cheers,
--renato