This is the mail archive of the
gdb@sourceware.org
mailing list for the GDB project.
Re: Issue with Latest GDB on AIX with GCC-6.12
- From: David Edelsohn <dje dot gcc at gmail dot com>
- To: Pedro Alves <palves at redhat dot com>
- Cc: Nitish Kumar Mishra <mishra dot nitish dot 88 at gmail dot com>, "gdb at sourceware dot org" <gdb at sourceware dot org>, Yao Qi <qiyaoltc at gmail dot com>
- Date: Tue, 7 Feb 2017 09:15:53 -0500
- Subject: Re: Issue with Latest GDB on AIX with GCC-6.12
- Authentication-results: sourceware.org; auth=none
- References: <CAGWvnyn0dfXfP8z+G0DFf4JWBZMXreetzg3+xX8_+7LYTmgw6Q@mail.gmail.com> <CAGWvny=e2W+H0VgGv_duZbW5A_LDFo9r9jpcB1U4f9mwwxZ_4A@mail.gmail.com> <21a21388-b1d9-816c-377e-d4e084cc399e@redhat.com> <CACC+hkgZxWgCC-4KR9M_c1=EU5GE4tagV61keSfYnDASXhN2EA@mail.gmail.com> <331a72d9-050c-7cd7-adc2-78e5f1ed6f85@redhat.com> <CAGWvny=snvFXj2zJr_WZcwqhqeC2S4if_LdtqJywtXS+NQvHcg@mail.gmail.com> <57147db4-83c3-2a8f-0c74-0efc6a94e9f5@redhat.com>
On Tue, Feb 7, 2017 at 8:56 AM, Pedro Alves <palves@redhat.com> wrote:
> On 02/07/2017 01:44 PM, David Edelsohn wrote:
>> On Tue, Feb 7, 2017 at 5:30 AM, Pedro Alves <palves@redhat.com> wrote:
>>
>>> Speaking of compilers, we know that building gdb with gcc 4.8.5
>>> doesn't run into this. Do we know that changed? Did, for example,
>>> AIX switch from sjlj to dwarf-based exceptions between gcc 4.8.5
>>> and 6.1? Might also be useful to try to build gdb with current
>>> gcc trunk / gcc 7.
>>
>> I cannot tell if some have reported that GCC 4.8.5 works correctly or not.
>
> The OP said it works fine on GCC 4.8.5 here:
>
> https://sourceware.org/ml/gdb/2017-01/msg00044.html
Yes, but I thought that there was a later comment that GCC 4.8 also
showed problems.
There was a change in the encoding of data for AIX, but not a change
to the basic EH frames or handlers. AIX did not change EH mechanisms
and never used SJLJ -- at least not for a very long time.
One test is to use shared libraries to link GDB.
Another possible contribution is the AIX address space. There have
been reports in the past of EH frames not sorted correctly and libgcc
EH not finding exception handlers because it terminated the search
early.
Thanks, David