[tree-ssa] performance regression after yesterdays mainline merge

[Richard Guenther]

Fariborz Jahanian wrote:
> 
> On Apr 2, 2004, at 1:09 AM, Richard Guenther wrote:
> 
>> Hi!
>>
>> The automatic tester at
>> http://www.tat.physik.uni-tuebingen.de/~rguenth/gcc/monitor- summary.html
>>
>> caught a performance regression of the compiled tramp3d-v3 code. It's a
>> 7.43s to 7.64s (per iteration) aka 3% regression.
>>
>> As this is between a mainline merge I suspect something from there  
>> causing
>> this regression (I don't monitor mainline, maybe I should).  Usually
>> regressins in this test are caused by FP loop pessimizations (as nearly
>> all time is spent there), and as this is ia64 I suspected
>>
>> 2004-03-29  Fariborz Jahanian <fjahanian@apple.com>
>>
>>         * fold-const.c (fold): Reassociate multiply expression
>>         with an adjacent non-multiply expression to use
>>         architecture's multiply-add instruction.
>>
>> to be the cause of the regression, but just reverting the above patch
>> causes another regression to 7.69s - so I'm lost.  Diffs of assembly  are
> 
> 
>  From above numbers, it seems to me that above patch is actually helping
> performance. It lowers the time to 7.64s which would otherwise have been
> 7.69s. I don't have access to an ia64 machine but I think investigation  
> should
> start with why this benchmark regressed to 7.69s (without above patch).

Yes, I read the numbers the same.  But maybe I screwed something up 
there - I cannot find another possible candidate from the ChangeLog. 
And as I'm ignorant of ia64 assembly trying to figure out what happened 
from the assembly side proved unsuccessful.

Oh well - maybe tomorrow its magically fixed...

Richard.

>> not helpful, as all non-label differences seem to be complete different
>> compiled routines.
>>
>> But you may notice the raise in bootstrap time which might (didnt  check)
>> be caused by a regression in gengtype which consumes quite a lot of
>> bootstrap time on ia64.
>>
>> Richard.
>>
>> -- 
>> Richard Guenther <richard dot guenther at uni-tuebingen dot de>
>> WWW: http://www.tat.physik.uni-tuebingen.de/~rguenth/
> 
>