[Mesa-dev] [LLVMdev] mesa-10.4.4: BROKEN TLS support in GLXwith llvm-toolchain v3.6.0rc2

[Sedat Dilek]

On Mon, Feb 16, 2015 at 10:39 AM, Marc Dietrich <marvin24 at gmx.de> wrote:
> Am Samstag, 14. Februar 2015, 18:20:12 schrieb Dimitry Andric:
>> On 11 Feb 2015, at 11:16, Sedat Dilek <sedat.dilek at gmail.com> wrote:
>> > On Wed, Feb 11, 2015 at 12:09 AM, Emil Velikov <emil.l.velikov at gmail.com>
> wrote:
>> >> On 10/02/15 13:17, Dimitry Andric wrote:
>> >>> On 09 Feb 2015, at 18:52, Sedat Dilek <sedat.dilek at gmail.com> wrote:
>> >>>> On Mon, Feb 9, 2015 at 6:44 PM, Emil Velikov <emil.l.velikov at gmail.com>
> wrote:
>> >>>>> On 07/02/15 22:42, Sedat Dilek wrote:
>> >>> ...
>> >>>
>> >>>>>> In file included from ../../src/mapi/entry.c:49:
>> >>>>>> ./entry_x86-64_tls.h:66:1: warning: tentative array definition
>> >>>>>> assumed
>> >>>>>> to have one element
>> >>>>>> x86_64_entry_start[];
>> >>>>>> ^
>> >>>>>> fatal error: error in backend: symbol 'x86_64_entry_start' is already
>> >>>>>> defined>>>
>> >>> ...
>> >>>
>> >>>>> It may be that it's a bug on our end, but it's a bit painful going
>> >>>>> through all the auto generated sources, the 10+ define guards and
>> >>>>> other
>> >>>>> magic that's inside src/mapi. Getting some idea on llvm/clang
>> >>>>> behaviour
>> >>>>> change should help out :-)
>> >>>>>
>> >>>>> Please open a bug-report with llvm and/or mesa, so that we have all
>> >>>>> the
>> >>>>> info in one place and things don't get lost.
>> >>>>
>> >>>> I am unsure if it is a bug in llvm/clang or in mesa.
>> >>>> Shall I open 2 bug-reports - in mesa and llvm BTS?
>> >>>
>> >>> Please have a look at this PR, which I opened in May 2014, and which is
> about the same issue:
>> >>>  http://llvm.org/PR19778
>> >>
>> >> Hi Dimitry,
>> >>
>> >> From a quick look at the bug, the llvm/clang devs are quoting the C11
>> >> spec, yet we're not building with -std=c11 so I'm not sure that applies.
>> >> Feel free to forward that if interested - I'm a bit short on account on
>> >> their bugzilla :-)
>> >>
>> >>> The assertion seems to have been transformed now into a backend error,
>> >>> but this may also be because you built clang without assertions. (Did
>> >>> you?)>>>
>> >>> In any case, the workaround is to change the static symbols into extern
> symbols, together with a hidden visibility attribute (as suggested by Rafael
> Espíndola), similar to the fix I posted in this FreeBSD port bug:
>> >>>  https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=192286
>> >>>
>> >>> E.g., you can use these patches:
>> >>>
>> >>> https://svnweb.freebsd.org/ports/head/graphics/libGL/files/patch-src__ma
>> >>> pi__entry_x86-64_tls.h?view=markup
>> >>> https://svnweb.freebsd.org/ports/head/graphics/libGL/files/patch-src__m
>> >>> api__entry_x86_tls.h?view=markup
>> >>> https://svnweb.freebsd.org/ports/head/graphics/libGL/files/patch-src__m
>> >>> api__entry_x86_tsd.h?view=markup>>
>> >> These patches don't look at all bad. Can you give them a bit of TLS and
>> >> send them to the list, please ? This also stands for the other patches
>> >> in FreeBSD's repo :-)
>> >
>> > On the one hand I am glad to see that there are patches available.
>> > I will give them a try when I am at home.
>> > On the other hand - knowing FreeBSD switched to llvm/clang as
>> > default-compiler - it's abit pity to see that stuff like this is not
>> > shared with upstream (did not look at the date of submission).
>> > If you have more patches in this area, please share them with upstream.
>>
>> The complete collection is here:
>>
>> https://svnweb.freebsd.org/ports/head/graphics/libGL/files/
>>
>> I didn't create most of these patches, so I can't really say what the
>> reason for them was, or whether they still apply to Mesa master.
>>
>> In any case, for this specific issue with Mesa's TLS related definitions
>> breaking clang, please consider the attached patch.
>
> I think there is no need to restrict this to clang only as it also works with
> gcc. I submitted a slightly different version to the mesa list which uses a
> macro instead and also adds some credits.
>

Sorry for the late response... troubles with my Internet connection.

Those two patches or do I need more?

[PATCH 1/4] configure: add visibility macro detection to configure
[PATCH 2/4] add visibility hidden to tls entry points

Regards,
- Sedat -

[1] http://lists.freedesktop.org/archives/mesa-dev/2015-February/076980.html
[2] http://lists.freedesktop.org/archives/mesa-dev/2015-February/076979.html