[Mesa-stable] [Mesa-dev] [PATCH] opencl: autotools: Fix linking order for OpenCL target

[Jan Vesely]

On Tue, 2018-05-01 at 18:23 +0200, Kai Wasserbäch wrote:
> Hey Jan,
> Jan Vesely wrote on 01.05.2018 17:19:
> > On Tue, 2018-05-01 at 14:14 +0200, Kai Wasserbäch wrote:
> > > Otherwise the build fails with an undefined reference to
> > > clang::FrontendTimesIsEnabled.
> > > 
> > > Bugzilla: https://bugs.freedesktop.org/106209
> > > Cc: mesa-stable at lists.freedesktop.org
> > > Cc: Jan Vesely <jan.vesely at rutgers.edu>
> > > Signed-off-by: Kai Wasserbäch <kai at dev.carbon-project.org>
> > > ---
> > > 
> > > Hey,
> > > this patch fixes a FTBFS for me with recent LLVM/Clang 7 revisions from
> > > upstream's SVN (I use the packages from apt.llvm.org).
> > > 
> > > If you accept it, please commit it for me, I do not have commit access.
> > > 
> > > The CC to stable can be dropped, if stable branches are not to be
> > > expected to be buildable with LLVM/Clang from SVN.
> > 
> > thanks for looking into this. TBH I don't understand how this patch
> > works, it's dropping and reordering linked libraries.
> > I've added Emil and Francisco to cc.
> 
> the removal is just the removal of a duplicate line (the first Clang library
> named is already "clangCodeGen"). And AFAICT there's no "-Wl,--as-needed" in
> use. At least I don't find anything in the build logs.
> 
> > >  src/gallium/targets/opencl/Makefile.am | 3 +--
> > >  1 file changed, 1 insertion(+), 2 deletions(-)
> > > 
> > > diff --git a/src/gallium/targets/opencl/Makefile.am b/src/gallium/targets/opencl/Makefile.am
> > > index de68a93ad5..f0e1de7797 100644
> > > --- a/src/gallium/targets/opencl/Makefile.am
> > > +++ b/src/gallium/targets/opencl/Makefile.am
> > > @@ -23,11 +23,10 @@ lib at OPENCL_LIBNAME@_la_LIBADD = \
> > >  	$(LIBELF_LIBS) \
> > >  	$(DLOPEN_LIBS) \
> > >  	-lclangCodeGen \
> > > -	-lclangFrontendTool \
> > >  	-lclangFrontend \
> > > +	-lclangFrontendTool \
> > 
> > This is strange. Why does reordering help here? Do we use -Wl,--as-
> > needed anywhere?
> 
> No, not that I can see.
> 
> > Should we use -Wl,--start-group/-Wl,--end-group for all clang libraries
> > instead?
> 
> Maybe? This was the simplest fix I could come up with, but if there's a
> preference for a link group, I can give that a try as well.

So the fix is to change ordering?
Does using groups fix the issue as well? I think that would be
preferable, but I use split .so files, so I don't hit this issue.

> 
> > >  	-lclangDriver \
> > >  	-lclangSerialization \
> > > -	-lclangCodeGen \
> > 
> > Is this change related?
> 
> Not really, just a minor clean-up while I was busy a few lines above.
> "clangCodeGen" is already named on the first Clang library line.

ah, all right, maybe mention it in the commit message?

Jan
> 
> Cheers,
> Kai
> 
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> mesa-dev at lists.freedesktop.org
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