Date: Sat, 13 Mar 1999 18:07:43 +0100
To: pgcc AT delorie DOT com
Subject: Re: amd and float
Message-ID: <19990313180743.G620@cerebro.laendle>
Mail-Followup-To: pgcc AT delorie DOT com
References: <19990312235917 DOT K9148 AT cerebro DOT laendle> <Pine DOT GSO DOT 4 DOT 05 DOT 9903130019520 DOT 18710-100000 AT legolas DOT mdh DOT se>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
In-Reply-To: <Pine.GSO.4.05.9903130019520.18710-100000@legolas.mdh.se>; from Henrik Berglund SdU on Sat, Mar 13, 1999 at 12:24:20AM +0100
X-Operating-System: Linux version 2.2.3 (root AT cerebro) (gcc driver version pgcc-2.93.09 19990221 (gcc2 ss-980929 experimental) executing gcc version 2.7.2.3) 
From: Marc Lehmann <pcg AT goof DOT com>
Reply-To: pgcc AT delorie DOT com
X-Mailing-List: pgcc AT delorie DOT com
X-Unsubscribes-To: listserv AT delorie DOT com
Precedence: bulk

On Sat, Mar 13, 1999 at 12:24:20AM +0100, Henrik Berglund SdU wrote:
> On 12 Mar 1999, Marc Lehmann wrote:
> 
> > The biggest probelm I see is that 3dnow uses different float formats than the
> > x86 fpu. even worse, you probably won't get improvements in the common case
> > anyway (doubles). also, the interoperability between the x86 fpu and 3dnow is
> > very bad.
> > 
> > the good thing is that, finally, its a sane design. a very sane design. if we
> > only had this design from the very beginning (and no x86 fpu).
> 
> Is it possible to just use 3dnow instead of the fpu does 3dnow have all
> the required instructions? if so it would be great if it only used the
> 3dnow for fpu operations when typing -march=3dnow or something :) 

Unfortunately, its not, as 3dnow does not support all dataformats and
instructions neccessary for this, so we still need the x86 fpu.

--  
      -----==-                                             |
      ----==-- _                                           |
      ---==---(_)__  __ ____  __       Marc Lehmann      +--
      --==---/ / _ \/ // /\ \/ /       pcg AT goof DOT com      |e|
      -=====/_/_//_/\_,_/ /_/\_\       XX11-RIPE         --+
    The choice of a GNU generation                       |
                                                         |