Loop unrolling-related SPEC regressions?

[Paolo Carlini]

Andreas Jaeger wrote:

>Paolo Carlini <pcarlini@unitus.it> writes:
>
>>Perhaps we could ask Andreas to help by running an exceptional SPEC test with
>>-funroll-loops instead (ideally, 2 different runs, pre- and post- the unroller
>>patch).
>>
>Sorry for joining in late, I've been travelling.
>
>Tell me exactly which patch I should revert and which compiler flags I
>should use and I'll bootstrap two GCCs and run one SPECint run using
>the different compilers for base and peak.
>
Thank you very much for your feedback Andreas.
With your help we could try to understand the following: RTH patch 
affects negatively SPEC runs (*) for a PEAK setup identical to that 
which you currently use *but* with -funroll-loops (instead of 
-funroll-all-loops) or not? In the process, we could also understand 
more of the issue itself -funroll-all-loops vs. -funroll-loops.
Therefore, if you agree, this is the patch which should be tentatively 
reverted:

    http://gcc.gnu.org/ml/gcc-patches/2002-01/msg02199.html

Thanks,
Paolo.

(*) When I say "affect negatively" I really mean the following: there is 
a good amount of evidence that due to that patch the following tests 
loose many points: 164.gzip, 186.crafty, 200.sixtrack.





>
>
>Andreas
>


-- 
Paolo Carlini
Dipartimento di Scienze Ambientali
Università degli Studi della Tuscia
Largo dell'Università , I-01100, Viterbo, ITALY