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Date: Mon, 12 May 2014 11:28:33 +0200
From: Natanael Copa <ncopa@...inelinux.org>
To: musl@...ts.openwall.com
Cc: dalias@...c.org, James Cloos <cloos@...loos.com>, Thomas Petazzoni
<thomas.petazzoni@...e-electrons.com>
Subject: Re: Broken GCC versions: 4.8.2 and 4.9.0
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).
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.
> > 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
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