40% performance regression SPEC2006/leslie3d on gcc-4_2-branch

Daniel Berlin dberlin@dberlin.org
Sun Feb 18 23:16:00 GMT 2007


On 2/18/07, Richard Guenther <richard.guenther@gmail.com> wrote:
> On 2/18/07, Daniel Berlin <dberlin@dberlin.org> wrote:
> > On 2/17/07, H. J. Lu <hjl@lucon.org> wrote:
> > > On Sat, Feb 17, 2007 at 01:35:28PM +0300, Vladimir Sysoev wrote:
> > > > Hello, Daniel
> > > >
> > > > It looks like your changeset listed bellow makes performance
> > > > regression ~40% on SPEC2006/leslie3d. I will try to create minimal
> > > > test for this issue this week and update you in any case.
> > > >
> > >
> > > That is a known issue:
> > >
> > > http://gcc.gnu.org/ml/gcc/2007-01/msg00408.html
> >
> > Yes, it is something we sadly cannot do anything about without doing a
> > very large number of backports.
> >
> > There were some seriously broken things in 4.2's aliasing that got
> > fixed properly in 4.3.
> > The price of fixing them in 4.2 was a serious performance drop.
>
> There's the option of un-fixing them to get back to the state of 4.1 declaring
> them fixed in 4.3 earliest.

This is fine by me, but they were rated as blockers.

>
> Richard.
>



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