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.