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[Bug target/40648] misaligned store vectorizer patch introduced 10% runtime regression on Polyhedron test_fpu
- From: "eres at il dot ibm dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 25 Oct 2009 12:41:49 -0000
- Subject: [Bug target/40648] misaligned store vectorizer patch introduced 10% runtime regression on Polyhedron test_fpu
- References: <bug-40648-1649@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #10 from eres at il dot ibm dot com 2009-10-25 12:41 -------
(In reply to comment #0)
> Hello!
> The "[patch, vectorizer] misaligned store support" patch [1] resulted in more
> than 10% longer execution time for Polyhedron test_fpu test on Core2.
> The test is compiled with "-march=x86-64 -ffast-math -funroll-loops -O3",
This patch changes wrongly the decision of when to peel the loop which causes
the negative effect on the performance.
I am preparing a patch to fix this.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40648