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Re: Broken isnan(3) and/or DQNAN on Tru64

From: Bruno Haible
Subject: Re: Broken isnan(3) and/or DQNAN on Tru64
Date: Sun, 3 May 2009 03:12:03 +0200
User-agent: KMail/1.9.9

Ludovic Courtès wrote:
> >> Should we conclude that this is a GCC bug?
> >
> > Possibly. And what result do you get with "gcc -mieee" ?
> It works (returns 1).
> The GCC manual (info "(gcc) DEC Alpha Options") reads this:
> `-mieee'
>      [...]
>      This option generates code fully IEEE compliant code [...]
>      The resulting code is less efficient but is able to correctly
>      support denormalized numbers and exceptional IEEE values such as
>      not-a-number and plus/minus infinity.

OK. So my conclusion is that without -mieee flag (or -ieee for cc), the
compiler does not deal with NaNs. GCC probably optimizes more aggressively
than cc in this case.

> So people compiling with GCC on this platform should pass `-mieee'
> (`configure' could add it automatically.)

The gnulib module 'fpieee' adds it automatically.


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