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In-Reply-To: <27fdc0d8dc588cfdb3a14a153c5d037c@physics.uc.edu>
Subject: Re: signed is undefined and has been since 1992 (in GCC)
To: Andrew Pinski <pinskia@physics.uc.edu>
Cc: gcc mailing list <gcc@gcc.gnu.org>
Message-ID: <OFC701B61A.2D69278F-ONC225702E.00175947-C225702E.0017D92F@il.ibm.com>
From: Michael Veksler <VEKSLER@il.ibm.com>
Date: Tue, 28 Jun 2005 04:20:00 -0000
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Andrew Pinski wrote on 28/06/2005 07:08:33:

> The first change in GCC which changed signed overflow/wrapping to be
> undefined
> was added back in 1992 in loop.c.  The next change was in 1999 with the
> addition of simplify-rtx.c.  Why are we talking about this now, instead
> of back
> when they were added?  (note both of these changes were before fwrapv
> can into
> play).
>
I don't mind MAX_INT+1 being undefined by gcc. I object to drawing from
"undefined" to conclude that is_modulo should be true. This does not
make a practical sense. Drawing conclusions from "undefined" can yield
absurd results.