[PATCH][AArch64] Set default sched pressure algorithm

[Maxim Kuvyrkov]

> 
> On Nov 2, 2017, at 9:41 PM, Wilco Dijkstra <Wilco.Dijkstra@arm.com> wrote:
> 
> The Arm backend sets the default sched-pressure algorithm to
> SCHED_PRESSURE_MODEL.  Benchmarking on AArch64 shows this 
> speeds up floating point performance on SPEC - eg. CactusBSSN improves
> by ~16%.  The gains are mostly due to less spilling, so enable this on AArch64
> by default.

Hi Wilco,

Any notable regressions?

> 
> OK for commit?

Looks good to me.

--
Maxim Kuvyrkov
www.linaro.org

> 
> 2017-11-02  Wilco Dijkstra  <wdijkstr@arm.com>
> 
> 	* config/aarch64/aarch64.c (aarch64_override_options_internal):
> 	Set PARAM_SCHED_PRESSURE_ALGORITHM to SCHED_PRESSURE_MODEL.
> 
> --
> diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
> index 34456e96497ac7b6d2f9931187ff05619e1934a4..750b0bc29c0963742d5d7bb4ae4619d93bec3e4a 100644
> --- a/gcc/config/aarch64/aarch64.c
> +++ b/gcc/config/aarch64/aarch64.c
> @@ -9276,6 +9276,11 @@ aarch64_override_options_internal (struct gcc_options *opts)
> 			   opts->x_param_values,
> 			   global_options_set.x_param_values);
> 
> +  /* Use the alternative scheduling-pressure algorithm by default.  */
> +  maybe_set_param_value (PARAM_SCHED_PRESSURE_ALGORITHM, SCHED_PRESSURE_MODEL,
> +			 opts->x_param_values,
> +			 global_options_set.x_param_values);
> +
>   /* Enable sw prefetching at specified optimization level for
>      CPUS that have prefetch.  Lower optimization level threshold by 1
>      when profiling is enabled.  */