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Re: [PATCH] fast Copysign for PPC, -flag_unsafe_math_optimizations only
- From: Richard Henderson <rth at redhat dot com>
- To: Andrew Pinski <pinskia at physics dot uc dot edu>
- Cc: gcc-patches Patches <gcc-patches at gcc dot gnu dot org>
- Date: Sun, 30 Jan 2005 17:32:04 -0800
- Subject: Re: [PATCH] fast Copysign for PPC, -flag_unsafe_math_optimizations only
- References: <8b9411a7771aeb1299d248ed5ca6020b@physics.uc.edu>
On Sun, Jan 30, 2005 at 07:12:40PM -0500, Andrew Pinski wrote:
> With this patch copysign is expanded to:
> fabs f0,f1
> fnabs f1,f1
> fsel f1,f2,f0,f1
>
> Which is faster and smaller than storing and doing
> bitfield operations on the sign bit.
I would be surprised if this ever gets used, but the proper
test is HONOR_SIGNED_ZEROS, not flag_unsafe_math_optimizations.
r~