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Re: -mno-fancy-math-387 doesn't work with -mpentium3
- From: Roger Sayle <roger at eyesopen dot com>
- To: "H. J. Lu" <hjl at lucon dot org>
- Cc: <gcc at gcc dot gnu dot org>
- Date: Mon, 22 Jul 2002 20:08:41 -0600 (MDT)
- Subject: Re: -mno-fancy-math-387 doesn't work with -mpentium3
Hi H.J.,
This is the documented behaviour of "-mno-fancy-math-387".
> -mno-fancy-math-387
> Some 387 emulators do not support the sin, cos and sqrt instructions
> for the 387. Specify this option to avoid generating those
> instructions. This option is the default on FreeBSD, OpenBSD and
> NetBSD. This option is overridden when -march indicates that the
> target cpu will always have an FPU and so the instruction will not
> need emulation. As of revision 2.6.1, these instructions are not
> generated unless you also use the -funsafe-math-optimizations switch.
As the pentium3 has an FPU, this option has no effect. I take
it you have a case where you'd like to generate optimized code
but without using fsin, fcos and fsqrt on the pentium III?
Perhaps "-fno-builtin-sin -fno-builtin-cos -fno-builtin-sqrt"?
Roger
--
Roger Sayle, E-mail: roger@eyesopen.com
OpenEye Scientific Software, WWW: http://www.eyesopen.com/
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