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From: FX <fxcoudert@gmail.com>
To: Joseph Myers <joseph@codesourcery.com>
Cc: GCC Mailing List <gcc@gcc.gnu.org>
Subject: Re: Weird behaviour (bug?) of __builtin_nans()
Date: Fri, 31 Dec 2021 20:14:02 +0100	[thread overview]
Message-ID: <A3E12C73-5000-4007-9E25-CA251997FBFC@gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.22.394.2112311653250.2293191@digraph.polyomino.org.uk>

Hi Joseph,

> 1. You should use -fsignaling-nans if you want signaling NaNs to work 
> correctly.

Thanks, we’ll compile the libgfortran parts that are IEEE-related with that from now on. Sounds like a good idea, anyway.


> 3. There is probably a reasonable case for interpreting such conversions 
> (including casts) as copy operations instead, including in the absence of 
> -fsignaling-nans; C23 Annex F leaves that implementation-defined, and 
> handling such conversions as copy operations is likely to be more 
> predictable and more useful.

I agree that while there may be no guarantee, it sounds like a reasonable expectation in the case I posted. I’ve filed a PR: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103883


Thanks,
FX

      reply	other threads:[~2021-12-31 19:14 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-31 16:13 FX
2021-12-31 17:05 ` Joseph Myers
2021-12-31 19:14   ` FX [this message]

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