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[Bug middle-end/29256] [4.3/4.4/4.5/4.6 regression] loop performance regression
- From: "sandra at codesourcery dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 21 Jul 2010 04:21:26 -0000
- Subject: [Bug middle-end/29256] [4.3/4.4/4.5/4.6 regression] loop performance regression
- References: <bug-29256-12262@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #37 from sandra at codesourcery dot com 2010-07-21 04:21 -------
It seems like the change was introduced by my patch for PR42505 in r161844.
But, it is correctly choosing the lower-cost candidate set -- the problem is in
the cost model, which was unchanged from r161843. Take a look at the
"Use-candidate costs" section of the dump. Those costs with negative values
(like -7) look very suspicious to me.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29256