From: Joseph Myers <joseph@codesourcery.com>
To: Ulrich Weigand <uweigand@de.ibm.com>
Cc: <libc-alpha@sourceware.org>
Subject: Re: fmax/fmin sNaN compatibility question
Date: Tue, 10 Dec 2019 18:05:00 -0000 [thread overview]
Message-ID: <alpine.DEB.2.21.1912101803360.4700@digraph.polyomino.org.uk> (raw)
In-Reply-To: <20191210104358.4F372D80305@oc3748833570.ibm.com>
On Tue, 10 Dec 2019, Ulrich Weigand wrote:
> Joseph Myers wrote:
> > On Mon, 9 Dec 2019, Ulrich Weigand wrote:
> > > Do you know why the sample implementation was even updated then?
> > > If FP_SNANS_ALWAYS_SIGNAL is false, shouldn't the C11 method then
> > > still be OK?
> >
> > The canonicalize call is needed in general to avoid propagating
> > noncanonical DFP encodings, though not relevant for binary FP.
>
> But it does change the behavior for binary FP as well, as far
> as I can see: e.g. if both inputs are sNaNs, the C11 method
> would return one of those sNaNs unchanged, while the C2x method
> will return a qNaN (as the canonicalize call will quiet the
> sNaN it receives as input), right?
The handling of sNaN is explicitly implementation-defined when
FE_SNANS_ALWAYS_SIGNAL is not defined, so that example implementation
should not be used to infer anything about how sNaN should be handled.
--
Joseph S. Myers
joseph@codesourcery.com
next prev parent reply other threads:[~2019-12-10 18:05 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-09 17:12 Ulrich Weigand
2019-12-09 17:23 ` Joseph Myers
2019-12-09 17:39 ` Ulrich Weigand
2019-12-10 1:00 ` Joseph Myers
2019-12-10 10:44 ` Ulrich Weigand
2019-12-10 18:05 ` Joseph Myers [this message]
2019-12-10 18:39 ` Ulrich Weigand
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