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Date: Fri, 13 Mar 1998 16:09:21 +0100
From: Thomas Koehler <T DOT Koehler AT pfh DOT research DOT philips DOT com>
Organization: Philips
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To: Tuukka Toivonen <tuukkat AT ees2 DOT oulu DOT fi>
CC: beastium-list AT Desk DOT nl
Subject: Re: paranoia & extra precision [was -fno-float-store in pgcc]
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Sender: Marc Lehmann <pcg AT goof DOT com>
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Tuukka Toivonen wrote:
> 
> On Thu, 12 Mar 1998, Marc Lehmann wrote:
> 
> >> There seems to be annother way, but involes the unducumented functions
> >> __getfpucw and 
> 
> Undocumented???? Those functions has nothing to do with the _hardware_ ->
> they are some OS/GCC thingies I don't know about -> GCC/OS is undocumented
> -> GCC/OS is broken (not really... with GNU software they're documented in
> source code, at least)
> 
> These functions probably use FPU instructions fstenv/fldenv, which are well
> documented in Intel Pentium manuals as well as internals of the FPU.

so what is the difference between the behaviour of programs compiled
with -ffloat-store compared to setting the FPU-rounding mode to double
via __setfpucw? (except that the -ffloat-store variante is much slower).

-- 



Thomas Koehler
Philips Research Laboratories
Division Technical Systems
Roentgenstrasse 24-26
D-22335 Hamburg
Germany

phone:  +40/5078-2103
e-mail: T DOT Koehler AT PFH DOT Research DOT Philips DOT com