Date: Thu, 27 Feb 2014 23:39:20 -0800 (PST) From: Don Lewis <truckman@FreeBSD.org> To: kaduk@mit.edu Cc: imb@protected-networks.net, freebsd-current@FreeBSD.org Subject: Re: firebox build fails post clang-3.4 merge Message-ID: <201402280739.s1S7dKUA095981@gw.catspoiler.org> In-Reply-To: <alpine.GSO.1.10.1402262124291.1213@multics.mit.edu>
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On 26 Feb, Benjamin Kaduk wrote: > On Wed, 26 Feb 2014, Don Lewis wrote: > >> On 26 Feb, Michael Butler wrote: >>> On 02/18/14 12:10, Michael Butler wrote: >>>> Is anyone else seeing firefox failing to install after the clang-3.4 >>>> merge? As in xpcshell dumping core .. >>> >>> An update .. >>> >>> Recompiling with GCC48 on -current yields the same result. Seems to run >>> correctly when invoked from the command-line but seg-faults with "errno >>> = 4" (invalid instruction) from the build >>> >>> Giving up and using the Linux port .. :-( >> >> I've also seen this problem with clang-3.4 on i386. It looks like a >> clang bug to me. Clang is putting ud2 instructions in its output which >> are guaranteed to fault when it compiles nsAppRunner.cpp. See >> <http://www.freebsd.org/cgi/query-pr.cgi?pr=187103>. > > That would seem to indicate that clang believes the source code in > question is exercising a case which is explicitly listed as giving > undefined behavior in the language specification. Presumably that means we > need a C++ language lawyer to look over the code in question. After spending the last couple of days pounding my head on my desk, I managed to come up with a standalone test case that reproduces this problem. The source is still on the hefty side because of all the C++ template goo (but more than an order of magnitude smaller than when I started) but the assembly code is fairly small. If updated my PR with the relevant info.
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