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[Bug tree-optimization/18694] [4.0 regression] loop miscompilation at -O1 (-ftree-ch)
- From: "kazu at cs dot umass dot edu" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 10 Dec 2004 21:31:28 -0000
- Subject: [Bug tree-optimization/18694] [4.0 regression] loop miscompilation at -O1 (-ftree-ch)
- References: <20041127224610.18694.falk@debian.org>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Additional Comments From kazu at cs dot umass dot edu 2004-12-10 21:31 -------
Subject: Re: [4.0 regression] loop
miscompilation at -O1 (-ftree-ch)
Hi Jeff,
> Err, no. You're totally warping how the the equivalency code is meant
> to work. It's a symmetric relationship and it's your patch that is
> making it asymmetric.
I thought SSA_NAME_VALUE gets me a gimple min invariant or the
earliest SSA_NAME that has the same value.
> Don't bother. The patch is wrong.
Can you come up with a hypothetical scenario?
Kazu Hirata
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18694