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Re: fmax/fmin sNaN compatibility question
- From: Joseph Myers <joseph at codesourcery dot com>
- To: Ulrich Weigand <uweigand at de dot ibm dot com>
- Cc: <libc-alpha at sourceware dot org>
- Date: Tue, 10 Dec 2019 01:00:07 +0000
- Subject: Re: fmax/fmin sNaN compatibility question
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- References: <20191209173923.C5D18D802DA@oc3748833570.ibm.com>
On Mon, 9 Dec 2019, Ulrich Weigand wrote:
> So just to clarify: there was a sample implementation in C11, and now there
> is a (different) sample implementation in TS 18661-1 / C2x, but the expected
> behavior in FP_SNANS_ALWAYS_SIGNAL mode is neither of those, but rather the
> behavior described by maxNum from IEEE 754-2008. Right?
Yes.
> 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.
--
Joseph S. Myers
joseph@codesourcery.com