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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 13:09:33 +0100 |
User-agent: |
Mutt/1.5.13-vl-r14963 (2006-12-20) |
On 2006-12-30 20:07:09 -0500, Robert Dewar wrote:
> In my view, this comparison optimization should not have been put in
> without justification given that it clearly does affect the semantics
> of real code. Indeed if you really see code like
>
> if (a - 10 < 20)
>
> in place of
>
> if (a < 30)
>
> a very likely explanation is that you are deliberately doing something
> strange with wrap around, and should leave it alone.
I disagree concerning your "very likely explanation". This code
may come from the use of macros, in which case this has nothing
to do with wrap around.
--
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 ...", Gabriel Dos Reis, 2006/12/30
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Richard Guenther, 2006/12/30
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Gabriel Dos Reis, 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 ...", Gabriel Dos Reis, 2006/12/30
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Andrew Pinski, 2006/12/30
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Gabriel Dos Reis, 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 ...", Andrew Pinski, 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 ...", 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 ...", 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 ...", 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 ...", Vincent Lefevre, 2006/12/31
- Re: changing "configure" to default to "gcc -g -O2 -fwrapv ...", Gerald Pfeifer, 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 ...", Gabriel Dos Reis, 2006/12/31