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[Bug c/54945] Too strong non-aliasing analysis?
- From: "jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 17 Oct 2012 12:06:59 +0000
- Subject: [Bug c/54945] Too strong non-aliasing analysis?
- Auto-submitted: auto-generated
- References: <bug-54945-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54945
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2012-10-17
CC| |jakub at gcc dot gnu.org
Ever Confirmed|0 |1
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-10-17 12:06:59 UTC ---
Doesn't look like alias analysis to me, I'd say the problem is in
fold_sign_changed_comparison which has:
if ((TYPE_UNSIGNED (inner_type) != TYPE_UNSIGNED (outer_type)
|| POINTER_TYPE_P (inner_type) != POINTER_TYPE_P (outer_type))
&& code != NE_EXPR
&& code != EQ_EXPR)
return NULL_TREE;
While for TYPE_UNSIGNED changes NE_EXPR/EQ_EXPR are just fine, for
POINTER_TYPE_P changes I'm afraid we just need to be conservative.