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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)
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", (continued)
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Bernd Schmidt, 2006/12/30
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Richard Kenner, 2006/12/30
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Paul Eggert, 2006/12/30
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Richard Kenner, 2006/12/30
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Paul Eggert, 2006/12/30
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Richard Kenner, 2006/12/30
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Robert Dewar, 2006/12/30
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...",
Vincent Lefevre <=
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Richard Kenner, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Vincent Lefevre, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Richard Kenner, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Vincent Lefevre, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Robert Dewar, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Richard Kenner, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Robert Dewar, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Vincent Lefevre, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Richard Kenner, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Robert Dewar, 2006/12/30