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Message-ID:	<35094C21.6B3F0566@pfh.research.philips.com>
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]
References:	<Pine DOT SOL DOT 3 DOT 96 DOT 980313133308 DOT 249A-100000 AT stekt10>
Sender:	Marc Lehmann <pcg AT goof DOT com>
Status:	RO
X-Status:	A
Lines:	32

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

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