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Date: Mon, 12 May 2014 10:30:55 -0400
From: "Anthony G. Basile" <basile@...nsource.dyc.edu>
To: musl@...ts.openwall.com
Subject: Re: Broken GCC versions: 4.8.2 and 4.9.0
On 05/12/14 05:28, Natanael Copa wrote:
> On Sun, 11 May 2014 17:20:30 -0400
> Rich Felker <dalias@...c.org> wrote:
>
>> On Sun, May 11, 2014 at 04:08:37PM -0400, James Cloos wrote:
>>>>>>>> "RF" == Rich Felker <dalias@...c.org> writes:
>>>
>>> RF> I've tested it on gcc.godbolt.org and others have tested with local
>>> RF> gcc 4.8.2 and 4.9.0, probably distro-provided (I didn't ask).
>>>
>>> I just tried debian-sid's 4.9. That does show the bug. As does their
>>> gcc-snapshot version (a 4.10 pre).
>>>
>>> Perhaps the distro(s) which have the bug with 4.8.2 backported the commit
>>> where the bug first occurs?
>>
>> Sounds plausible. Maybe that will help find the offending commit.
>
> I have tried to reproduce the issue on Alpine Linux without success. We
> have gcc-4.8.2 with lots of patches from gentoo and with a hardened
> default (default enabled).
All the gentoo+musl stages on the gentoo tree are built with 4.7.3 so I
can't speak to this issue.
>
> I have tried run with GCC_SPECS=vanilla (should disable the hardened
> part) and without the -Os without any difference.
>
> It would be interesting to know what patches was used on the affected
> gcc-4.8.2 systems.
What gcc gentoo patches are you using? Even vanilla gentoo has some.
>
>>> RF> I wonder if the broken GCC is using isl/cloog
>>>
>>> I use the graphite optimizer on my Gentoo box (which generated the
>>> assembly I quoted). The graphite code is only used when one or more
>>> of -floop-interchange -floop-strip-mine -floop-block are specified.
>>>
>>> Testing with those options doesn't change the results.
>>
>> OK, ruled that out then.
>
> We also have a patch[1] that will dlopen libcloog-isl.so.4 instead of
> link to it directly for upgrade purposes. I have tried to build musl
> with and without libcloog-isl.so.4 installed without it making any
> difference.
>
>
>>
>> Rich
--
Anthony G. Basile, Ph. D.
Chair of Information Technology
D'Youville College
Buffalo, NY 14201
(716) 829-8197
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