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[Bug tree-optimization/48702] [4.6/4.7 Regression] optimization regression with gcc-4.6 on x86_64-unknown-linux-gnu
- From: "xinliangli at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 21 Apr 2011 16:22:22 +0000
- Subject: [Bug tree-optimization/48702] [4.6/4.7 Regression] optimization regression with gcc-4.6 on x86_64-unknown-linux-gnu
- Auto-submitted: auto-generated
- References: <bug-48702-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48702
--- Comment #12 from davidxl <xinliangli at gmail dot com> 2011-04-21 16:22:03 UTC ---
(In reply to comment #3)
> I have a patch that makes it fail on trunk as well. IVOPTs generates
>
> for (p = &a; p != &a - 3; --p)
> *(p + 3) = ...
>
> and alias analysis doesn't like this invalid pointer.
I wonder why ivopt does not select the iv candidate whose base is &a+3.