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[Bug tree-optimization/15524] [4.0 Regression] jump threading on trees is slow with switch statements with large # of cases
- From: "pinskia at physics dot uc dot edu" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 3 Nov 2004 15:08:58 -0000
- Subject: [Bug tree-optimization/15524] [4.0 Regression] jump threading on trees is slow with switch statements with large # of cases
- References: <20040518194300.15524.pinskia@gcc.gnu.org>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Additional Comments From pinskia at physics dot uc dot edu 2004-11-03 15:08 -------
Subject: Re: [4.0 Regression] jump threading on trees is slow with switch statements with large # of cases
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.
Thanks,
Andrew Pinski
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15524