Re: -freduce-all-givs and fortran

[Andreas Jaeger <aj at suse dot de>]

Andreas Jaeger <aj@suse.de> writes:

> Just for reference, I've run the SPECfp2000 Fortran77 tests once with
> these flags on an AMD Athlon 1.133 Ghz system:
>
> Base: -O2 -march=athlon -malign-double
> Peak: -O2 -march=athlon -malign-double -fno-move-all-movables  -fno-reduce-all-givs
>
> Here're the results:
>                                     Estimated                     Estimated
>                    Base      Base      Base      Peak      Peak      Peak
>    Benchmarks    Ref Time  Run Time   Ratio    Ref Time  Run Time   Ratio
>    ------------  --------  --------  --------  --------  --------  --------
>    168.wupwise       1600     418         382*     1600     417         384*
>    171.swim          3100    1213         256*     3100    1040         298*
>    172.mgrid         1800    1017         177*     1800    1117         161*
>    173.applu         2100     759         277*     2100     813         258*
>    200.sixtrack      1100     577         191*     1100     534         206*
>
> 301.apsi had some errors and couldn't be tested.
>
> Using -fno-move-all-movables  -fno-reduce-all-givs is a performance
> gain for 171.swim and 200.sixtrack but pessimizes 172.grid and
> 173.app, 168.wupwise is indifferent.

Toon Moene asked:
|> Fascinating ... Do 171.swim and 200.sixtrack profit from loop
|> optimization *at all* ?  What happens if you use
|> 
|> -O2 -march=athlon -malign-double -fno-strength-reduce

The numbers with -O2 -march=athlon -malign-double -fno-strength-reduce
are:
             Run Time  Ratio
168.wupwise    444      360
171.swim      1012      306
172.mgrid     1036      174
173.applu      816      258
200.sixtrack   556      198

Andreas
-- 
 Andreas Jaeger
  SuSE Labs aj@suse.de
   private aj@arthur.inka.de
    http://www.suse.de/~aj