Date: Sat, 13 Sep 2014 22:00:58 +0400 From: Andrey Chernov <ache@freebsd.org> To: Dimitry Andric <dim@FreeBSD.org> Cc: toolchain@freebsd.org Subject: Re: clang makes segfaulting code with -march=core2 on i386 Message-ID: <5414865A.6030101@freebsd.org> In-Reply-To: <6FDF432B-8245-4BC7-952B-DFFEEA106D6F@FreeBSD.org> References: <54130AD0.8090103@freebsd.org> <A212D7AF-4DA7-4043-BB73-1746A5C2F42F@FreeBSD.org> <54133E1E.9030105@freebsd.org> <54135B24.5040905@freebsd.org> <54135D0B.7060701@freebsd.org> <6FDF432B-8245-4BC7-952B-DFFEEA106D6F@FreeBSD.org>
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[-- Attachment #1 --] On 13.09.2014 20:45, Dimitry Andric wrote: > After some massaging of gcc's source to disable its built-in segfault > handlers, I get this backtrace: Do you get this with my core or finally able to reproduce it by yourself? > I think it's most likely this is some type of undefined behavior in gcc, > which leads to randomly corrupted tree values. Of course, it could also > be a clang bug, but I don't see any "64-bit" instructions in there at > all. > > This needs to be investigated further, but it's very hard to understand > what is going on the guts of gcc's parser. Let alone to reduce this to > some sort of reproducible test case. By first glance I see a lots of <optimized out> things. It is known that in edge cases gcc preserves more "unused" values than clang. It can be the possible case. I'll try to lower -O level preserving -march=core2 and see. -- http://ache.vniz.net/ [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- iQEcBAEBCAAGBQJUFIZaAAoJEKUckv0MjfbKvDcH/jJIOeC+TalKXt2DFGkKvW3x T9dMEGXISSdt4y5z9/EdKCDtHY5YPu0QOjCaSHLRRfOYiW2cpKoUdw7rjzRyq4Sm q+Ys97X16ttCUaaeh0EpT1oKEyh7OSvv/MA77zAPO/ep3fER6pM7BZmhj5IxZ8N7 x8Zco6birUT7GoXuiRPIExXJnz6ceUou2kF6bEiuTMiV3dU/c18v6TK2O1WMz5hm ZdDY6DoWbNcQi5y13ESs/iTFcxyRut/A0WwllbLfyVXcXi6mmYBPclKgzj9ILHp0 4KegthiD7FWYZ88SPohltLdY57CyY9T0eiPoTsxNGGb4f3BUWGD79ccaWm52neg= =xzzE -----END PGP SIGNATURE-----help
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