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 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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