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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 Jan 2008 16:31:19 -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 #10 from ubizjak at gmail dot com 2008-01-19 16:31 -------
(In reply to comment #9)
> Does the regression on C2 duo show even without vectorizing? It looks like
> generic SSE fpmath performance issue. There should be no reason why SSE math
> in combination with SSE vectorization should result in regression...
Hm, using latest SVN, the C2D difference is only marginal:
gfortran -O3 -m64 -march=core2 -msse3 -ffast-math -funroll-loops
-ftree-loop-linear
-fno-tree-vectorize -fno-vect-cost-model
-mfpmath=sse 21.37 21.38 21.41
-mfpmath=387 20.73 20.64 20.69
vendor_id : GenuineIntel
cpu family : 6
model : 15
model name : Intel(R) Core(TM)2 CPU X6800 @ 2.93GHz
stepping : 5
cpu MHz : 2933.422
cache size : 4096 KB
gcc version 4.3.0 20080119 (experimental) [trunk revision 131650] (GCC)
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31897