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Re: Autoconf manual's coverage of signed integer overflow & portability
- From: Andrew Haley <aph at redhat dot com>
- To: Andrew Pinski <pinskia at physics dot uc dot edu>
- Cc: eggert at CS dot UCLA dot EDU (Paul Eggert), autoconf-patches at gnu dot org, autoconf at gnu dot org, bug-autoconf at gnu dot org, bug-gnulib at gnu dot org, gcc at gcc dot gnu dot org
- Date: Wed, 3 Jan 2007 10:07:00 +0000
- Subject: Re: Autoconf manual's coverage of signed integer overflow & portability
- References: <87irfoinic.fsf@penguin.cs.ucla.edu> <200701030735.l037ZhV3019023@localhost.localdomain>
Andrew Pinski writes:
>
> This will always cause a trap on x86, even with -fwrapv so really
> -fwrapv has a bug on x86. I will file this bug sometime later
> tomorrow. Oh and fixing this bug will actually slow down users
> of -fwrapv even more than what it is currently does because
> you can no longer use the div instruction.
Actually, you can still use div, but it's rather tricky. There's some
code in libgcj to handle this very situation.
Andrew.