[Mesa-dev] [PATCH WIP 1/1] configure: include llvm systemlibs when using static llvm

[Jan Vesely]

On Wed, 2014-10-29 at 19:00 +0000, Emil Velikov wrote:
> On 27/10/14 21:03, Jan Vesely wrote:
> > On Mon, 2014-10-27 at 20:22 +0000, Emil Velikov wrote:
> >> On 27/10/14 18:05, Jan Vesely wrote:
> >>> On Mon, 2014-10-27 at 02:24 +0000, Emil Velikov wrote:
> >>>> On 26/10/14 19:36, Jan Vesely wrote:
> >>>>> On Fri, 2014-10-24 at 23:54 +0000, Emil Velikov wrote:
> >>>>>> On 24/10/14 17:03, Jan Vesely wrote:
> >>>>>>> -Wl,--exclude-libs prevents automatic export of symbols
> >>>>>>>
> >>>>>>>
> >>>>>>> CC: Kai Wasserbach <kai at dev.carbon-project.org>
> >>>>>>> CC: Emil Velikov <emil.l.velikov at gmail.com>
> >>>>>>> Signed-off-by: Jan Vesely <jan.vesely at rutgers.edu>
> >>>>>>> ---
> >>>>>>>
> >>>>>>> Kai,
> >>>>>>> can you try this patch with your setup, and check whether LLVM symbols are
> >>>>>>> exported from mesa library? (and it's still working)
> >>>>>>>
> >>>>>>> Emil,
> >>>>>>> would it help to have --exclude-libs ALL enabled globally?
> >>>>>>>
> >>>>>> Haven't really looked up on the documentation about it, yet there should
> >>>>>> be no (unneeded) exported symbols thanks to the version scripts.
> >>>>>> As such I'm not entirely sure what this patch (attempts to) resolve :(
> >>>>>
> >>>>> you are right. I don't know why I thought it was still a problem.
> >>>>> In that case the attached patch should fix compiling with llvm static
> >>>>> libs (#70410)
> >>>>>
> >>>> For future patches please add the full link in the commit message
> >>>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=70410
> >>>>
> >>>> Afaics the bug mentioned has a slightly different patch, which brings
> >>>> the question - do we need to append to the existing LLVM_LIBS, or can we
> >>>> overwrite them ? Either way it would be nice if we can get a tested-by
> >>>> or two :)
> >>>
> >>> Hi,
> >>>
> >>> I looked at this again. LLVM cmake links system-libs as either PUBLIC or
> >>> INTERFACE [0].
> >>> it means my patch is incorrect, and we should link against system-libs
> >>> even if we use llvm-shared-libs.
> >>> you can add my R-b to the patch by K. Sobiecky that is attached to the
> >>> bug.[1]
> >>>
> >> Sigh... "cmake why you so PoS ?"
> >>
> >> On a more mature note:
> >> I do not see why would we need it to link against those libraries for
> >> shared linking. If their libs are broken (have unresolved symbols), and
> >> we need this hack to get them working then maybe, but
> >> ... looking at line 151 - # FIXME: Should this be really PUBLIC?
> >> Answer: PRIVATE for shared libs, PUBLIC for static ones.
> >>
> >> Using PUBLIC causes all the users to recursively link against those
> >> deps. Leading to over-linking and opening the door for serious issues.
> > 
> > looks like misdesign on llvm side. they use public to bring systemlibs
> > to other llvm libs, while ignore private deps elsewhere (like libffi).
> > I'd try to send a patch, but my last attempt to get Alexander's rtti
> > patch in is stuck for 9 months...
> > 
> Yes, dealing with build systems is a job no-one wants to do, and I fear
> most people underestimate it. Please let them know and be persistent
> otherwise they might will end up abusing it too much :)

just FYI
the llvm cmake part got fixed in r221530 and r221531.

> 
> > anyway, since we only need those libs in static builds, do you want me
> > to repost the patch with bug reference and Kai's tested by?
> > 
> There is no problem. I've picked it up, added the tags + cc'd
> mesa-stable, as I would expect a few more people willing to use mesa
> with static linked llvm.
> 
> Thanks
> Emil
> 
> > jan
> > 
> >>
> >>
> >> -Emil
> >>
> >> P.S. Both their automake + cmake builds seems _quite_ bad.
> >> autoconf/Readme has a nice documentation of it :)
> >>
> >>
> >>> jan
> >>>
> >>>
> >>> [0] lib/Support/CMakeLists.txt:150
> >>> [1] https://bugs.freedesktop.org/attachment.cgi?id=91764
> >>>>
> >>>> Thanks
> >>>> Emil
> >>>>
> >>>>> jan
> >>>>>
> >>>>>>
> >>>>>> -Emil
> >>>>>>
> >>>>>>> jan
> >>>>>>>
> >>>>>>>  configure.ac | 10 +++++++++-
> >>>>>>>  1 file changed, 9 insertions(+), 1 deletion(-)
> >>>>>>>
> >>>>>>> diff --git a/configure.ac b/configure.ac
> >>>>>>> index 3c76deb..b4b4b13 100644
> >>>>>>> --- a/configure.ac
> >>>>>>> +++ b/configure.ac
> >>>>>>> @@ -1981,7 +1981,15 @@ if test "x$MESA_LLVM" != x0; then
> >>>>>>>             dnl already added all of these objects to LLVM_LIBS.
> >>>>>>>          fi
> >>>>>>>      else
> >>>>>>> -        AC_MSG_WARN([Building mesa with staticly linked LLVM may cause compilation issues])
> >>>>>>> +        AC_MSG_WARN([Building mesa with statically linked LLVM may cause compilation issues])
> >>>>>>> +	dnl Don't export symbols automatically
> >>>>>>> +	dnl TODO: Do we want to list llvm libs explicitly here?
> >>>>>>> +	LLVM_LDFLAGS+=" -Wl,exclude-libs ALL"
> >>>>>>> +	dnl We need to link to llvm system libs when using static libs
> >>>>>>> +	dnl However, only llvm 3.5+ provides --system-libs
> >>>>>>> +	if test $LLVM_VERSION_MAJOR -eq 3 -a $LLVM_VERSION_MINOR -ge 5; then
> >>>>>>> +		LLVM_LIBS+=" `$LLVM_CONFIG --system-libs`"
> >>>>>>> +	fi
> >>>>>>>      fi
> >>>>>>>  fi
> >>>>>>>  
> >>>>>>>
> >>>>>>
> >>>>>
> >>>>
> >>>
> >>
> > 
> 

-- 
Jan Vesely <jan.vesely at rutgers.edu>
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