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Re: [BENCHMARK]-mfpmath=sse should disable x387 intrinsics


On Thu, 25 Nov 2004, Richard Guenther wrote:
> Now I actually read the patch and looked at the patch context.
> Simulating the effect of your patch results in
>
> -mfpmath=sse -mno-fancy-math-387 -D__NO_MATH_INLINES: 55.8s
> -mfpmath=sse -mno-fancy-math-387: 55.8s
>
> Oh - and your patch misses updating of the documentation of -mfpmath (and
> possibly -mno-fancy-math-387).

Now you've misread the documentation for -mno-fancy-math-387 which
currently has absolutely no effect on recent processors:

const int x86_arch_always_fancy_math_387 = m_PENT | m_PPRO | m_ATHLON_K8
					   | m_PENT4 | m_NOCONA;


Before complaining much more, might I strongly suggest that you actually
try running some benchmarks with current CVS.  Clearly, you're not exactly
sure what the performance impact of my patch is/will be.  I'd not rule out
that there could be a performance improvement in which case much of the
previous discussions would be moot.

Roger
--


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