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[Bug rtl-optimization/32084] gfortran 4.3 13%-18% slower for induct.f90 than gcc 4.0-based competitor
- From: "ubizjak at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 27 Jun 2007 11:24:30 -0000
- Subject: [Bug rtl-optimization/32084] gfortran 4.3 13%-18% slower for induct.f90 than gcc 4.0-based competitor
- References: <bug-32084-13404@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #4 from ubizjak at gmail dot com 2007-06-27 11:24 -------
(In reply to comment #3)
> The problem is in -ftree-vectorize
The difference is, that without -ftree-vectorize the inner loop (do k = 1, 9)
is completely unrolled, but with vectorization, the loop is vectorized, but
_not_ unrolled. Since the vectorization factor is only 2 for V2DF mode vectors,
we loose big time at this point.
My best guess for unroller problems would be rtl-optimization.
--
ubizjak at gmail dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
CC|dorit at gcc dot gnu dot org|
Component|tree-optimization |rtl-optimization
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32084