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From: "pthaugen at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/54497] [4.8 Regression] Revision 190015 causes 22% degradation on 172.mgrid on PowerPC
Date: Thu, 06 Sep 2012 21:05:00 -0000 [thread overview]
Message-ID: <bug-54497-4-fuSLNDoKdS@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-54497-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54497
--- Comment #2 from Pat Haugen <pthaugen at gcc dot gnu.org> 2012-09-06 21:05:05 UTC ---
(In reply to comment #1)
> I suppose the loop is no longer predicted to execute enough times?
I don't think that's the issue, I'm thinking it's somewhere in the data
dependence analysis. Looking at the dump before .pcom (i.e. .dceloop3), both
resid_ and resid_.constprop.0 list BB7, the inner loop block, as freq=10000.
The .pcom dump has many differences in the data analysis portion between the
two procedures, but the main difference is the analysis on resid_.constprop.0
ends with the following:
Predictive commoning failed: no suitable chains
next prev parent reply other threads:[~2012-09-06 21:05 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-05 21:46 [Bug tree-optimization/54497] New: " pthaugen at gcc dot gnu.org
2012-09-06 10:02 ` [Bug tree-optimization/54497] [4.8 Regression] " rguenth at gcc dot gnu.org
2012-09-06 21:05 ` pthaugen at gcc dot gnu.org [this message]
2012-09-12 15:30 ` dje at gcc dot gnu.org
2012-09-21 21:55 ` pthaugen at gcc dot gnu.org
2012-11-06 17:04 ` hubicka at gcc dot gnu.org
2012-11-16 13:22 ` hubicka at gcc dot gnu.org
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