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Re: [Bug tree-optimization/15524] [4.0 Regression] jump threading on trees is slow with switch statements with large # of cases


On Wed, 3 Nov 2004 10:07:58 -0500, Andrew Pinski <pinskia@physics.uc.edu> wrote:
> 
> On Nov 3, 2004, at 10:03 AM, Jeffrey A Law wrote:
> 
> >
> > With loop bounds recording no longer charged to the expander it's time
> > to deal with the inefficiencies which are in the switch expander.
> >
> > Basically we have code which does
> >
> > for each case
> >   for each case
> >     see if the label in the outer loop matches any of the cases in the
> >     inner loop (up to the current case in the outer loop).
> 
> We don't really need some of this code anyways because the gimplifier
> now reorders the case statements so that you don't have to do the loop
> at all.

I believe I have seen patches from Kazu that address this.

Richard.


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