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[Bug target/31897] [4.3 Regression] 30% speed regression with -m32 on Opteron with rnflow
- From: "ubizjak at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 19 Oct 2007 17:53:02 -0000
- Subject: [Bug target/31897] [4.3 Regression] 30% speed regression with -m32 on Opteron with rnflow
- References: <bug-31897-13404@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #7 from ubizjak at gmail dot com 2007-10-19 17:53 -------
(In reply to comment #6)
> It is little bit sick, but what about implying -mfpmath=sse when
> -ftree-vectorize is used and SSE is available?
Then you will hit Core2 Duo, that shows the opposite in 32bit and 64bit mode:
-O3 -ffast-math -ftree-vectorize -funroll-loops -msse3 -m32 -mfpmath=387
user 0m22.785s
-O3 -ffast-math -ftree-vectorize -funroll-loops -msse3 -m32 -mfpmath=sse
user 0.27.886s
-O3 -ffast-math -ftree-vectorize -funroll-loops -msse3 -m64 -mfpmath=387
user 0m20.473s
-O3 -ffast-math -ftree-vectorize -funroll-loops -msse3 -m64 -mfpmath=sse
user 0.25.046s
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31897