Re: [patch] Disable tree-ssa DSE for now

[Steven Bosscher <stevenb at suse dot de>]

On Wednesday 19 January 2005 07:44, Mark Mitchell wrote:
> Jeffrey A Law wrote:
> >>I agree.  If the optimizer experts agree that this pass is ineffective,
> >>Steven's patch should be applied.
> >
> > It largely depends on what one considers ineffective.  I can say with
> > absolute confidence that the current implementation is able to eliminate
> > stores that the RTL implementation is unable to eliminate.
>
> That doesn't sound all that ineffective to me, then.  I'm not eager to
> disable stuff that's doing some good.

But the question is whether or not it is worth the effort.  There is
a compile time penalty, that's for sure.  Remember: 54 stores in a
very large code base.  Many of those would probably have been caught
by the RTL pass too.  If that "some good" costs ~1% compile time, it
is IMHO not worth it.

I guess I'll have to put up more numbers, because clearly Jeff is not
going to do it (*sigh* I remember the cd-dce discussion - apparently
his own rules do not apply to him).

Gr.
Steven