Re: [PATCH 4/4] powerpc: Remove f{max,min}{f} assembly implementations

["Tulio Magno Quites Machado Filho" <tuliom at linux dot vnet dot ibm dot com>]

Adhemerval Zanella <adhemerval.zanella@linaro.org> writes:

> This patch removes the powerpc assembly implementation of fmax/fmin.
> Based on benchtests, the assembly ones shows:
>
> $ ./testrun.sh benchtests/bench-fmax
>   "fmax": {
>    "": {
>     "duration": 5.07586e+09,
>     "iterations": 2.01676e+09,
>     "max": 1350.39,
>     "min": 2.073,
>     "mean": 2.51684
>    },
>    "qNaN": {
>     "duration": 5.09315e+09,
>     "iterations": 8.4568e+08,
>     "max": 2788,
>     "min": 5.806,
>     "mean": 6.02255
>    },
>    "sNaN": {
>     "duration": 5.09073e+09,
>     "iterations": 8.42316e+08,
>     "max": 4215.84,
>     "min": 5.737,
>     "mean": 6.04373
>    }
>
> And
>
> $ ./testrun.sh benchtests/bench-fmin
>   "fmin": {
>    "": {
>     "duration": 5.07711e+09,
>     "iterations": 2.02982e+09,
>     "max": 497.094,
>     "min": 2.073,
>     "mean": 2.50126
>    },
>    "qNaN": {
>     "duration": 5.09134e+09,
>     "iterations": 8.46968e+08,
>     "max": 2255.14,
>     "min": 5.807,
>     "mean": 6.01125
>    },
>    "sNaN": {
>     "duration": 5.09122e+09,
>     "iterations": 8.4746e+08,
>     "max": 1969.38,
>     "min": 5.729,
>     "mean": 6.00763
>    }
>   }
>
> The default implementation (math/s_f{max.min}_template.c) shows slight better
> latency for all cases:
>
> $ ./testrun.sh benchtests/bench-fmax
>   "fmax": {
>    "": {
>     "duration": 5.07044e+09,
>     "iterations": 2.38695e+09,
>     "max": 2048.58,
>     "min": 2.073,
>     "mean": 2.12423
>    },
>    "qNaN": {
>     "duration": 5.09004e+09,
>     "iterations": 9.45428e+08,
>     "max": 3306.93,
>     "min": 5.138,
>     "mean": 5.38385
>    },
>    "sNaN": {
>     "duration": 5.08458e+09,
>     "iterations": 1.15959e+09,
>     "max": 972.008,
>     "min": 3.321,
>     "mean": 4.3848
>    }
>   }
>
> And:
>
> $ ./testrun.sh benchtests/bench-fmin
>   "fmin": {
>    "": {
>     "duration": 5.06817e+09,
>     "iterations": 2.3913e+09,
>     "max": 1177.9,
>     "min": 2.073,
>     "mean": 2.11942
>    },
>    "qNaN": {
>     "duration": 5.08857e+09,
>     "iterations": 9.45656e+08,
>     "max": 2658.83,
>     "min": 5.09,
>     "mean": 5.38099
>    },
>    "sNaN": {
>     "duration": 5.08093e+09,
>     "iterations": 1.16725e+09,
>     "max": 1030.74,
>     "min": 3.323,
>     "mean": 4.3529
>    }
>   }
>
> Both were run with GCC 5.4 (ubuntu 16 default installation) using default
> compiler flags on POWER8E 3.4GHz (powerpc64le-linux-gnu).

LGTM.

For the record: the results with older GCC versions (e.g. 4.8) are getting
worse, but I don't think this regression in an old GCC version should block
this patch.

-- 
Tulio Magno