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[Bug tree-optimization/14741] missing transformations lead to poorly optimized code
- From: "jv244 at cam dot ac dot uk" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 28 Jan 2005 16:31:33 -0000
- Subject: [Bug tree-optimization/14741] missing transformations lead to poorly optimized code
- References: <20040326121739.14741.jv244@cam.ac.uk>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Additional Comments From jv244 at cam dot ac dot uk 2005-01-28 16:31 -------
> You could try "gfortran -O3 -mtune=pentium4 -ffast-math -mfpmath=sse
> -ftree-loop-linear -ftree-vectorize yourcode.f90" and see if it helps.
Unhappily, seems to make things slower:
multgen/basic_mult> gfortran -O3 -mtune=pentium4 -ffast-math -mfpmath=sse
-ftree-loop-linear -ftree-vectorize mult.f90
mult.f90:0: warning: SSE instruction set disabled, using 387 arithmetics
multgen/basic_mult> ./a.out
60.3900000000000 10.2400000000000
whereas removing some of these flags helps a little
multgen/basic_mult> gfortran -O3 -mtune=pentium4 -ffast-math mult.f90
multgen/basic_mult> ./a.out
56.4700000000000 10.2400000000000
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14741