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

[Marc Dietrich]

Am Montag, 16. Februar 2015, 12:42:19 schrieb 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

no that's all, sorry I still have two unrelated patches in my HEAD. So this 
should actually have been /2.

Marc

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