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[Bug tree-optimization/37194] Autovectorization of small constant iteration loop degrades performance
- From: "dorit at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 22 Aug 2008 13:31:31 -0000
- Subject: [Bug tree-optimization/37194] Autovectorization of small constant iteration loop degrades performance
- References: <bug-37194-14936@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #3 from dorit at gcc dot gnu dot org 2008-08-22 13:31 -------
(In reply to comment #2)
> The x86_64 generated code looks like
...
> I wonder why we do not use movups instead.
> t.i:3: note: Alignment of access forced using peeling.
> t.i:3: note: Peeling for alignment will be applied.
because the vectorizer doesn't support misaligned stores. I think it should be
easy to add - see this old patch:
http://gcc.gnu.org/ml/gcc-patches/2007-01/msg00604.html (and also on
http://gcc.gnu.org/wiki/VectorizationTasks, under "todo").
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37194