On Mon, Jan 25, 2016 at 11:20:46AM +0000, James Greenhalgh wrote: > On Mon, Jan 11, 2016 at 12:04:43PM +0000, James Greenhalgh 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? > > *Ping*
*pingx2* Thanks, James > > --- > > 2015-12-11 James Greenhalgh <james.greenha...@arm.com> > > > > * config/aarch64/aarch64.c (cortexa57_tunings): Remove > > AARCH64_EXTRA_TUNE_RECIP_SQRT. > > > > > diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c > > index 1d5d898..999c9fc 100644 > > --- a/gcc/config/aarch64/aarch64.c > > +++ b/gcc/config/aarch64/aarch64.c > > @@ -484,8 +484,7 @@ static const struct tune_params cortexa57_tunings = > > 0, /* max_case_values. */ > > 0, /* cache_line_size. */ > > tune_params::AUTOPREFETCHER_WEAK, /* autoprefetcher_model. */ > > - (AARCH64_EXTRA_TUNE_RENAME_FMA_REGS > > - | AARCH64_EXTRA_TUNE_RECIP_SQRT) /* tune_flags. */ > > + (AARCH64_EXTRA_TUNE_RENAME_FMA_REGS) /* tune_flags. */ > > }; > > > > static const struct tune_params cortexa72_tunings = >
