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Re: signed is undefined and has been since 1992 (in GCC)
- From: Michael Veksler <VEKSLER at il dot ibm dot com>
- To: Andrew Pinski <pinskia at physics dot uc dot edu>
- Cc: gcc mailing list <gcc at gcc dot gnu dot org>
- Date: Tue, 28 Jun 2005 07:20:29 +0300
- Subject: Re: signed is undefined and has been since 1992 (in GCC)
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.