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[Bug tree-optimization/54855] Unnecessary duplication when performing scalar operation on vector element
- From: "glisse at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Fri, 12 Oct 2012 18:08:45 +0000
- Subject: [Bug tree-optimization/54855] Unnecessary duplication when performing scalar operation on vector element
- Auto-submitted: auto-generated
- References: <bug-54855-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54855
--- Comment #5 from Marc Glisse <glisse at gcc dot gnu.org> 2012-10-12 18:08:45 UTC ---
Doing the optimization that late is a bit fragile though. For instance:
v[0] += 3.0;
v[0] -= 1.0;
is back to decomposing the vector, doing the operations and reconstructing it
(I didn't use -fassociative-math so it couldn't turn that into += 2.0). But
doing more looks too complicated.