[tree-ssa] performance regression after yesterdays mainline merge

[Fariborz Jahanian]

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).

- Fariborz

> 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/