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[Bug target/31897] [4.3 Regression] 30% speed regression with -m32 on Opteron with rnflow
- From: "hubicka at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 9 Oct 2007 14:55:01 -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 #6 from hubicka at gcc dot gnu dot org 2007-10-09 14:54 -------
It is little bit sick, but what about implying -mfpmath=sse when
-ftree-vectorize is used and SSE is available?
The reason why we don't default to fpmath=sse is because the extra precision is
told to be part of i386 ABI, with vectorization we are not going to maintain
this "feature" anyway.
I can easily imagine that many users will try -ftree-vectorize and forget about
-mfpmath...
Honza
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31897