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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
- From: Richard Guenther <richard dot guenther at gmail dot com>
- To: Andrew Pinski <pinskia at physics dot uc dot edu>
- Cc: law at redhat dot com, gcc-patches at gcc dot gnu dot org, gcc-bugzilla at gcc dot gnu dot org
- Date: Wed, 3 Nov 2004 16:44:11 +0100
- Subject: Re: [Bug tree-optimization/15524] [4.0 Regression] jump threading on trees is slow with switch statements with large # of cases
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- Reply-to: Richard Guenther <richard dot guenther at gmail dot com>
On Wed, 3 Nov 2004 10:07:58 -0500, Andrew Pinski <email@example.com> 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.