Date: Fri, 29 Aug 2014 18:34:00 +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: <9EC067FB-EE88-4C6D-A0B2-E90467683A5B@gmail.com> In-Reply-To: <1408992488.1150.105.camel@revolution.hippie.lan> 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> <834BA562-84ED-425C-9D61-0A235A28A94A@gmail.com> <1408472517.56408.659.camel@revolution.hippie.lan> <F4EE79A6-9D99-4EE1-9452-2C7ECF963646@gmail.com> <1408562392.1150.4.camel@revolution.hippie.lan> <2C97B126-91FE-4E93-920F-6ED5045666A6@gmail.com> <1408992488.1150.105.camel@revolution.hippie.lan>
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On 25 Aug 2014, at 20:48 , Ian Lepore <ian@FreeBSD.org> wrote: > On Thu, 2014-08-21 at 18:54 +0200, Olavi Kumpulainen wrote: >> On 20 Aug 2014, at 21:19 , Ian Lepore <ian@FreeBSD.org> wrote: >> >>> On Wed, 2014-08-20 at 19:19 +0200, Olavi Kumpulainen wrote: >>>> On 19 Aug 2014, at 20:21 , Ian Lepore <ian@FreeBSD.org> wrote: >>>> >>>>> On Tue, 2014-08-19 at 19:40 +0200, Olavi Kumpulainen wrote: >>>>>> 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] >>>>>>>>> >>>>>>>>> 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. >>>>>>>>> >>>>>>>>> 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. >>>>>>>>> >>>>>>>>> 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.) >>>>>>>>> >>>>>>>>> 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. >>>>>>>>> >>>>>>>>> -- Ian >>>>>>>> >>>>>>>> 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. >>>>>>> >>>>>>> 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..... >>>>>>> >>>>>>> Andreas >>>>>>> >>>>>>> >>>>>> >>>>>> Please excuse my late reply. IĒve 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, IĒm obviously missing something. Do any of you guys have any ideas? >>>>>> >>>>>> Cheers >>>>>> >>>>> >>>>> I'm not sure what you mean by "backported to stable/10", I merged all >>>>> the necessary changes to stable-10 as r269792 on Aug 10. Are you >>>>> working with a checkout from earlier than that? If so, just updating >>>>> should fix it for you. >>>>> >>>>> -- Ian >>>>> >>>>> >>>> >>>> >>>> Updating to stable-10 as of today didnĒt help. IĒm running a clean checkout except for a couple of drivers in the kernel. >>>> This makes me think I have a bad src.conf - How shall I configure the build for this to work? >>>> >>>> /Olavi >>>> >>>> >>>> >>>> >>> >>> You need to use GCC, not clang, as the compiler. Exceptions are just >>> broken on clang 3.4, so we're waiting for 3.5 (should be released any >>> time now I think). >>> >>> To compile with gcc, put this in your /etc/make.conf: >>> >>> WITH_GCC=yes >>> WITH_GNUCXX=yes >>> WITH_GCC_BOOTSTRAP=yes >>> WITHOUT_CLANG=yes >>> WITHOUT_CLANG_IS_CC=yes >>> WITHOUT_CLANG_BOOTSTRAP=yes >>> >>> -- Ian >>> >>> >> >> >> Thank you. It turned out that I already used these with the exception of WITHOUT_CLANG_BOOTSTRAP. >> >> However, c++ exceptions in stable/10 is still defunct when I build it. >> >> So instead I pulled master, built and installed that instead. And voila - Exceptions do work! >> >> Therefore it seems my build method, flags and environment is ok after all. I glanced the commit logs in master but didnĒt find anything obvious, but still; something related seems missing in stable/10 if you ask me. >> >> /Olavi >> >> >> >> _______________________________________________ >> freebsd-arm@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-arm >> To unsubscribe, send any mail to "freebsd-arm-unsubscribe@freebsd.org" >> > > I chased this down today to a missing MFC. One of my merges claimed to > include a change that wasn't really included. I fixed it today with > r270606, and this time I actually tested that I could throw and catch an > exception using freebsd built from stable-10 at this rev. :) > > Thanks for testing this, and sorry for claiming it was fixed when it > wasn't quite complete. > > -- Ian > > IĒm a little late again, but I still want to confirm that stable/10 works for me too. It catches c++ exceptions like a real champ! Thanks a million - /Olavihome | help
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