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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 15:39:15 +0100
User-agent: Mutt/1.5.13-vl-r14963 (2006-12-20)

On 2006-12-31 09:03:17 -0500, Richard Kenner wrote:
> > And I doubt that GCC (or any compiler) could reliably detect code
> > that checks for overflow.
> It doesn't need to "detect" all such code: all it needs to do is
> ensure that it doesn't BREAK such code. And that's a far easier
> condition: you just have to avoid folding a condition into TRUE or
> FALSE based on assumptions about overflow.

Well, that's not equivalent. For instance, MPFR has many conditions
that evaluate to TRUE or FALSE on some/many implementations (mainly
because the type sizes depend on the implementation), even without
the assumption that an overflow cannot occur.

Vincent Lefèvre <address@hidden> - Web: <>
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Work: CR INRIA - computer arithmetic / Arenaire project (LIP, ENS-Lyon)

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