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: >>=20 >>> 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: >>>>=20 >>>>> 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: >>>>>>=20 >>>>>>> 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 >>>>>>=20 >>>>>> Please excuse my late reply. I=A2ve been away from keyboard for a = while. >>>>>>=20 >>>>>> 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. >>>>>>=20 >>>>>> Since this seems to work ok in HEAD, I=A2m obviously missing = something. Do any of you guys have any ideas? >>>>>>=20 >>>>>> Cheers >>>>>>=20 >>>>>=20 >>>>> 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. >>>>>=20 >>>>> -- Ian >>>>>=20 >>>>>=20 >>>>=20 >>>>=20 >>>> Updating to stable-10 as of today didn=A2t help. I=A2m 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? >>>>=20 >>>> /Olavi >>>>=20 >>>>=20 >>>>=20 >>>>=20 >>>=20 >>> 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). >>>=20 >>> To compile with gcc, put this in your /etc/make.conf: >>>=20 >>> WITH_GCC=3Dyes >>> WITH_GNUCXX=3Dyes >>> WITH_GCC_BOOTSTRAP=3Dyes >>> WITHOUT_CLANG=3Dyes >>> WITHOUT_CLANG_IS_CC=3Dyes >>> WITHOUT_CLANG_BOOTSTRAP=3Dyes >>>=20 >>> -- Ian >>>=20 >>>=20 >>=20 >>=20 >> Thank you. It turned out that I already used these with the exception = of WITHOUT_CLANG_BOOTSTRAP. >>=20 >> However, c++ exceptions in stable/10 is still defunct when I build = it.=20 >>=20 >> So instead I pulled master, built and installed that instead. And = voila - Exceptions do work!=20 >>=20 >> Therefore it seems my build method, flags and environment is ok after = all. I glanced the commit logs in master but didn=A2t find anything = obvious, but still; something related seems missing in stable/10 if you = ask me. >>=20 >> /Olavi >>=20 >>=20 >>=20 >> _______________________________________________ >> 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" >>=20 >=20 > 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. :) >=20 > Thanks for testing this, and sorry for claiming it was fixed when it > wasn't quite complete. >=20 > -- Ian >=20 >=20 I=A2m 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 - /Olavi
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