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Re: PATCH: Enable FTZ/DAZ for SSE via fast math


On Wed, Aug 10, 2005 at 10:18:41AM -0400, Jakub Jelinek wrote:
> On Wed, Aug 10, 2005 at 07:09:04AM -0700, H. J. Lu wrote:
> > On Tue, Aug 09, 2005 at 02:58:51PM -0700, Richard Henderson wrote:
> > > On Tue, Aug 09, 2005 at 02:30:46PM -0700, H. J. Lu wrote:
> > > > There is a minor problem. How can I add crtfastmath.o for SSE targets
> > > > only? 
> > > 
> > > You don't.  You either add code to detect sse, or you make the
> > > spec depend on -mfpmath=sse.
> > > 
> > 
> > Here is the patch to enable FTZ/DAZ for SSE via fast math. There are
> > no regressions on Linux/x86_64 nor Linux/ia32. The performance of one
> > FP benchmark on EM64T is more than doubled with -ffast-math.
> 
> Not all i?86 CPUs support cpuid instruction.
> Please look at
> gcc/testsuite/gcc.dg/i386-cpuid.h
> for the ugly details.
> 

Ok. Also all x86_64 supports SSE. There is no need to check that in
64bit.


H.J.


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