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Re: GCC optimizes integer overflow: bug or feature?
From: |
Andrew Haley |
Subject: |
Re: GCC optimizes integer overflow: bug or feature? |
Date: |
Tue, 19 Dec 2006 08:22:30 +0000 |
Robert Dewar writes:
> Brooks Moses wrote:
>
> > Now, if your argument is that following the LIA-1 standard will
> > prevent optimizations that could otherwise be made if one
> > followed only the C standard, that's a reasonable argument, but
> > it should not be couched as if it implies that preventing the
> > optimizations would not be following the C standard.
>
> I continue to suspect that the gains from this optimization are minimal
> to non-existent in practice. Given the requirements in LIA-1, I would
> think that taking advantage of overflow being undefined is only
> acceptable
That's an interesting use of the passive voice. Acceptable to whom?
> if there is very clear quantitative data showing that this indeed
> is a significant optimization.
We've already defined `-fwrapv' for people who need nonstandard
arithmetic. I don't see that this is any different from the
interminable strict-aliasing discussion.
Andrew.
- Re: GCC optimizes integer overflow: bug or feature?, (continued)
- Re: GCC optimizes integer overflow: bug or feature?, Paul Eggert, 2006/12/19
- Re: GCC optimizes integer overflow: bug or feature?, Joseph S. Myers, 2006/12/19
- Re: GCC optimizes integer overflow: bug or feature?, Paul Eggert, 2006/12/19
- Re: GCC optimizes integer overflow: bug or feature?, Gabriel Dos Reis, 2006/12/19
- Re: [bug-gnulib] GCC optimizes integer overflow: bug or feature?, Bruno Haible, 2006/12/19
- Re: GCC optimizes integer overflow: bug or feature?, Ian Lance Taylor, 2006/12/20
- Re: GCC optimizes integer overflow: bug or feature?, Joe Buck, 2006/12/20
- Re: GCC optimizes integer overflow: bug or feature? (was: avoid integer overflow in mktime.m4), Andrew Pinski, 2006/12/19
- Re: GCC optimizes integer overflow: bug or feature?, Brooks Moses, 2006/12/19
- Re: GCC optimizes integer overflow: bug or feature?, Robert Dewar, 2006/12/19
- Re: GCC optimizes integer overflow: bug or feature?,
Andrew Haley <=
- Re: GCC optimizes integer overflow: bug or feature?, Robert Dewar, 2006/12/19
- Re: GCC optimizes integer overflow: bug or feature?, Andrew Pinski, 2006/12/19
- Re: GCC optimizes integer overflow: bug or feature?, Robert Dewar, 2006/12/19
- Re: GCC optimizes integer overflow: bug or feature?, Florian Weimer, 2006/12/19
- Re: GCC optimizes integer overflow: bug or feature?, Paolo Bonzini, 2006/12/19
- Re: GCC optimizes integer overflow: bug or feature?, Florian Weimer, 2006/12/19
- Re: GCC optimizes integer overflow: bug or feature?, Robert Dewar, 2006/12/19
- Re: GCC optimizes integer overflow: bug or feature?, Joseph S. Myers, 2006/12/19
- Re: GCC optimizes integer overflow: bug or feature?, Robert Dewar, 2006/12/19
- Re: GCC optimizes integer overflow: bug or feature?, Paolo Bonzini, 2006/12/19