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Re: [PATCH] use hw instructions for ieee754_sqrt on s390.
- From: Martin Schwidefsky <schwidefsky at de dot ibm dot com>
- To: Ulrich Drepper <drepper at redhat dot com>
- Cc: libc-alpha at sources dot redhat dot com
- Date: Fri, 18 Jun 2004 10:31:08 +0200
- Subject: Re: [PATCH] use hw instructions for ieee754_sqrt on s390.
Ulrich Drepper <drepper@redhat.com> wrote on 18/06/2004 01:49:44 AM:
> Martin Schwidefsky wrote:
>
> > use the hardware square root instructions sqdbr and sqebr
> > for __ieee754_sqrt and __ieee754_sqrtf. They are faster
> > than the generic C implementation.
>
> I can do it even faster:
>
> double sqrt(double x) { return 1.0; }
Yes that is even faster ;-) But serious the hw instruction should
be exact to the last bit. The math test run fine. I have to ask
some hardware guys to make really sure about it though.
After I checked I'll post a new patch with the inline implementation.
blue skies,
Martin
Linux/390 Design & Development, IBM Deutschland Entwicklung GmbH
Schönaicherstr. 220, D-71032 Böblingen, Telefon: 49 - (0)7031 - 16-2247
E-Mail: schwidefsky@de.ibm.com