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Re: bug in check for stack growth direction in _AC_LIBOBJ_ALLOCA
From: |
Eric Blake |
Subject: |
Re: bug in check for stack growth direction in _AC_LIBOBJ_ALLOCA |
Date: |
Mon, 20 Jun 2011 11:56:22 -0600 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110428 Fedora/3.1.10-1.fc14 Lightning/1.0b3pre Mnenhy/0.8.3 Thunderbird/3.1.10 |
On 06/17/2011 04:21 AM, Andy Wingo wrote:
> address@hidden:/tmp$ gcc -O1 -o test foo.c
> address@hidden:/tmp$ ./test; echo $?
> 1
> address@hidden:/tmp$ gcc -O3 -o test foo.c
> address@hidden:/tmp$ ./test; echo $?
> 0
If I understand correctly, 0 is a correct result, just not optimal.
Improvements for getting the optimal result in spite of gcc
optimizations are welcome (the more we can determine at compile time,
the less work we have to do at runtime), but any correctly written
program should already handle the case of an indeterminate compile-time
probe (the probe should return 1 or -1 for known directions, and 0 for
undetermined direction).
--
Eric Blake address@hidden +1-801-349-2682
Libvirt virtualization library http://libvirt.org
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- Re: bug in check for stack growth direction in _AC_LIBOBJ_ALLOCA, (continued)
- Re: bug in check for stack growth direction in _AC_LIBOBJ_ALLOCA, Andy Wingo, 2011/06/20
- Re: bug in check for stack growth direction in _AC_LIBOBJ_ALLOCA, Eric Blake, 2011/06/20
- Re: bug in check for stack growth direction in _AC_LIBOBJ_ALLOCA, Paul Eggert, 2011/06/20
- Re: bug in check for stack growth direction in _AC_LIBOBJ_ALLOCA, Ralf Wildenhues, 2011/06/21
- Re: bug in check for stack growth direction in _AC_LIBOBJ_ALLOCA, Paul Eggert, 2011/06/21
Re: bug in check for stack growth direction in _AC_LIBOBJ_ALLOCA,
Eric Blake <=