Date: Tue, 19 Aug 2014 19:40:50 +0200 From: Olavi Kumpulainen <olavi.m.kumpulainen@gmail.com> To: Ian Lepore <ian@freebsd.org> Cc: freebsd-arm@freebsd.org Subject: Re: C++ exceptions in freebsd-arm doesn't seem to work Message-ID: <834BA562-84ED-425C-9D61-0A235A28A94A@gmail.com> In-Reply-To: <53D2CFBE.3040207@fgznet.ch> References: <BEAC4CFB-EC4F-456D-8173-2E34CCE3A2C1@gmail.com> <1405809318.85788.35.camel@revolution.hippie.lan> <1406063473.71975.8.camel@revolution.hippie.lan> <53D2CFBE.3040207@fgznet.ch>
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On 25 Jul 2014, at 23:44 , Andreas Tobler <andreast-list@fgznet.ch> = wrote: > On 22.07.14 23:11, Ian Lepore wrote: >> On Sat, 2014-07-19 at 16:35 -0600, Ian Lepore wrote: >>> On Sat, 2014-06-07 at 14:12 +0200, Olavi Kumpulainen wrote: >>>> [c++ exceptions don't work and related discussion] >>>=20 >>> I checked in a partial fix for c++ exception handling in r268893. = It >>> fixes the specific problem you detailed above, which was essentially >>> that the __gnu_Unwind_Find_exidx() function was not available in any >>> shared library, making the unwinder fall back to using the = __exidx_start >>> and end symbols, which are only valid in a statically-linked app. >>>=20 >>> With the new function in place, exceptions are closer to working = with >>> gcc 4.2.1, but still don't work with clang. With gcc, some things = work >>> and some things don't. For example if you throw an exception and in = the >>> same function have a catch with the right specific type it = segfaults, >>> but a catch(...) will catch it without problems. But you can catch = an >>> exception by type if the catch is in a function higher up the call = chain >>> from the place it was thrown. >>>=20 >>> We're continuing to debug this at $work, and welcome any input if = anyone >>> else makes progress with it. Right now we still don't know whether = the >>> segfaults are because of bad unwinder library code or bad unwind = data >>> emitted by gcc. (I sure hope it's the library, because that's = easier to >>> fix.) >>>=20 >>> On the clang front, it has been said that c++ exceptions work in = clang >>> 3.5, so we tried the clang-devel port, and it didn't just work. But = it >>> turns out that port hasn't been updated for quite a while, so we may = not >>> have tested the code that's supposed to work right. While trying = that I >>> discovered that clang 3.5 isn't scheduled for release for about = another >>> year, so that really isn't a viable solution for anyone with = near-term >>> needs, unless the required changes can be cherry-picked and brought = into >>> our version of 3.4. >>>=20 >>> -- Ian >>=20 >> Another update to this... today I committed r268993 and r268994, and = now >> I believe arm eabi c++ exceptions are fully working with gcc. I = haven't >> run an extensive test suite, but all the test cases we've been using = at >> $work to debug this now work correctly. >=20 > Thank you! Confirmed. My test cases which are working with gcc-4.10 = are now also working with the system gcc, 4.2.1. > I totally forgot about this change. I have it in my local gcc tree = since a while but I forgot about..... >=20 > Andreas >=20 >=20 Please excuse my late reply. I=92ve been away from keyboard for a while. I back-ported r268893, r268993 and r268994 to stable/10 for beaglebone. = C++ exceptions works for static builds, but not for binaries linked to = shared libs. Since this seems to work ok in HEAD, I=92m obviously missing something. = Do any of you guys have any ideas? Cheers /Olavi
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