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Re: [BENCHMARK]-mfpmath=sse should disable x387 intrinsics
- From: Richard Guenther <richard dot guenther at gmail dot com>
- To: Uros Bizjak <uros at kss-loka dot si>
- Cc: gcc-patches at gcc dot gnu dot org, Roger Sayle <roger at eyesopen dot com>
- Date: Thu, 25 Nov 2004 14:28:31 +0100
- Subject: Re: [BENCHMARK]-mfpmath=sse should disable x387 intrinsics
- References: <41A5A363.7010308@kss-loka.si>
- Reply-to: Richard Guenther <richard dot guenther at gmail dot com>
On Thu, 25 Nov 2004 10:18:27 +0100, Uros Bizjak <uros@kss-loka.si> wrote:
> Hello Roger!
>
> I have done a couple of whetstone benchmarks with your patch to disable
> x387 intrinsics on pentium4, 3.2 GHz. As it can be seen from attached
> results, the best results can be obtained with the combination of sse
> and i387 math. This combination is the fastest one, acheiving more than
> 8% gain, comparing to the default of i387 only.
>
> -mfpmath=sse is the worst choice in case of pentium4. The result is
> lower by 18%, comparing to the default. That is, -mfpmath=sse,387 is
> faster by 28%, comparing to -mfpmath=sse on pentium4.
For me, specifying -mfpmath=sse,387 is 4% slower than -mfpmath=sse. I gues
that 387 does not only enable 387 intrinsics but also all other
regular patterns?
I would prefer the -mfpmath=sse behavior _not_ to be changed for ia32.
Thanks,
Richard.