Date: Fri, 25 Jul 2014 23:44:30 +0200 From: Andreas Tobler <andreast-list@fgznet.ch> 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: <53D2CFBE.3040207@fgznet.ch> In-Reply-To: <1406063473.71975.8.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>
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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
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