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Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."

From: Vincent Lefevre
Subject: Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."
Date: Sun, 31 Dec 2006 12:24:19 +0100
User-agent: Mutt/1.5.13-vl-r14963 (2006-12-20)

On 2006-12-30 19:29:58 -0500, Robert Dewar wrote:
> Richard Kenner wrote:
> >I can't speak for any other GCC developer, but I personally am
> >quite comfortable viewing any code that assumes wrapping semantics
> >as broken and needing fixing with the exception of these cases of
> >checking for overflow: there simply is no good way in C to do these
> >checks in a portable manner and, as I said, I think we should make
> >sure they continue to work and maybe even document that.
> Now that I don't like, Richard is recommending we write in some
> undefined language where wraps sometimes work and sometimes
> don't. That seems the worst of all worlds to me.

I agree with you. And I doubt that GCC (or any compiler) could
reliably detect code that checks for overflow.

Vincent Lefèvre <address@hidden> - Web: <http://www.vinc17.org/>
100% accessible validated (X)HTML - Blog: <http://www.vinc17.org/blog/>
Work: CR INRIA - computer arithmetic / Arenaire project (LIP, ENS-Lyon)

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