Hi!
On Wed, Nov 25, 2020 at 02:02:16PM +0800, Kewen.Lin wrote:
> This patch is to set param_vect_partial_vector_usage as 1 on P10
> by default. Due to the unexpected performance on Power9 of those
> vector with length instructions, we didn't enable vectorization
> with partial vectors before. Some recent testings show that they
> perform expectedly on Power10 now. The performance evaluation
> on the whole SPEC2017 with latest trunk and option set power10/
> Ofast/unroll shows it can speed up 525.x264_r by 10.80% and
> 554.roms_r by 1.94%. One remarkable degradation is 523.xalancbmk_r
> -1.79% but it's identified not directly related to this enablement
> by some investigation.
> + if (TARGET_POWER10)
> + SET_OPTION_IF_UNSET (&global_options, &global_options_set,
> + param_vect_partial_vector_usage, 1);
> + else
> + /* Disable it on the default supported hardware Power9 since
> + lxvl/stxvl have unexpected performance behaviors. */
> + SET_OPTION_IF_UNSET (&global_options, &global_options_set,
> + param_vect_partial_vector_usage, 0);
Maybe write this like
/* The lxvl/stxvl instructions don't perform well before Power10. */
if (TARGET_POWER10)
SET_OPTION_IF_UNSET (&global_options, &global_options_set,
param_vect_partial_vector_usage, 1);
else
SET_OPTION_IF_UNSET (&global_options, &global_options_set,
param_vect_partial_vector_usage, 0);
Okay for trunk with such a comment (before the "if"). Thanks!
Segher
