Issue with Latest GDB on AIX with GCC-6.12

David Edelsohn dje.gcc@gmail.com
Tue Feb 7 14:16:00 GMT 2017


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



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