[AArch64] Remove AARCH64_EXTRA_TUNE_RECIP_SQRT from Cortex-A57 tuning

[Dr. Philipp Tomsich]

James,

ok from our side—good to see that this also benefits the A57.

Best,
Philipp.

> On 11 Jan 2016, at 13:04, James Greenhalgh <james.greenhalgh@arm.com> wrote:
> 
> 
> Hi,
> 
> I've seen a couple of large performance issues caused by expanding
> the high-precision reciprocal square root for Cortex-A57, so I'd like
> to turn it off by default.
> 
> This is good for art (~2%) from Spec2000, bad (~3.5%) for fma3d from
> Spec2000, good (~5.5%) for gromcas from Spec2006, and very good (>10%) for
> some private microbenchmark kernels which stress the divide/sqrt/multiply
> units. It therefore seems to me to be the correct choice to make across
> a number of workloads.
> 
> Bootstrapped and tested on aarch64-none-linux-gnu with no issues.
> 
> OK?
> 
> Thanks,
> James
> 
> ---
> 2015-12-11  James Greenhalgh  <james.greenhalgh@arm.com>
> 
> 	* config/aarch64/aarch64.c (cortexa57_tunings): Remove
> 	AARCH64_EXTRA_TUNE_RECIP_SQRT.
> 
> <0001-AArch64-Remove-AARCH64_EXTRA_TUNE_RECIP_SQRT-from-Co.patch>