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[Bug rtl-optimization/19780] Floating point computation far slower for -mfpmath=sse
- From: "ubizjak at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 6 Apr 2007 06:37:29 -0000
- Subject: [Bug rtl-optimization/19780] Floating point computation far slower for -mfpmath=sse
- References: <bug-19780-1649@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #21 from ubizjak at gmail dot com 2007-04-06 07:37 -------
Strange things happen.
I have fully removed gcc build directory and bootstrapped gcc from scratch. To
my suprise, the difference with -msse and without -msse is now gone and
optimized dumps are now the same. For reference, the compiler has ident "gcc
version 4.3.0 20070406 (experimental)".
Regarding this bug - SSE performance vs x87 performance is clearly target
procesor dependant. There is nothing gcc can do, and even without memory acces,
SSE is slower than x87 on some targets (ref: Comment #5).
Let's close this bug as WONTFIX, as there is nothing to fix in gcc.
--
ubizjak at gmail dot com changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |WONTFIX
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19780