Building a static library of OpenMP

[ikitayama]

Hi,
Is building a static library of OpenMP still designed to be
difficult to accomplish in the trunk?

[Alexey_Bataev1]

Hi Itaru, yes, it is not easy work to do. We discussed it again a few days ago and it still requires some additional work.

Best regards,
Alexey Bataev

[ikitayama]

Is it again disclosed to the public testers in the Clang 10 timeframe?

[ikitayama]

Alexey, all,
My platform requires apps be built statically, so creating libomp.a is a critical mission for me.
If there is documentation in the work out there, would you share it with us please?

[AndreyChurbanov]

Hi Itaru,

Building libomp.a is pretty easy, you can read some details in readme file (e.g. here https://github.com/llvm/llvm-project/tree/master/openmp).

But it won’t build static offload library. So, if you need offload that may be a problem, as Alexey mentioned. If you don’t need offload, than it should be easy.

Regards,

Andrey

[ikitayama]

Andrey,
I’d like the offload included in the toolchain.

[Gheorghe-Teod_Bercea]

Hi Itaru,

What version of Clang are you using?

I have a version which supports static linking at this page:

https://github.com/clang-ykt

Clone the llvm, clang and openmp repos and use the patched-upstream branch on all three.

Then build as you normally do.

This is a version that is quite recent, updated to newest development trunk yesterday.

Let me know if this works.

Thanks,

–Doru

[ikitayama]

Doru et al.,

My build was initiated on AArch64 like below:

cmake -G “Ninja” -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$HOME/opt/clang-ykt -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ -DLLVM_TARGETS_TO_BUILD=AArch64 ~/projects/clang-ykt/

Clang is provided from upstream as of yesterday-ish. The build process went ok, but I ended up obtaining a libomp.so.
(I made sure that BUILD_SHARED_LIBS was set to OFF, clang was located under the tools directory and openmp under projects)

Itaru.

[ikitayama]

Spoke too soon. Setting LIBOMP_ENABLE_SHARED to FALSE gives me libomp.a on AArch64.

[ikitayama]

Doru,

If you could turn the clang-ykt repository to a single one (llvm-project ish), that’d be easier for us
to catch your progress on a daily basis.

Thanks,
Itaru.

[ikitayama]

Doru,

On PowerPC (a POWER8 Minsky node), Ninja build is stuck on this phase:

$ ninja install
[0/3] Building CXX object tools/clang/…gDynamicASTMatchers.dir/Registry.cpp.o

… and no progress, it seems. Have you successfully finished building the patched-upstream branches
on PowerPC?

Thanks,
Itaru.

[Gheorghe-Teod_Bercea]

Hi Itaru,

I don’t have any issues on building on PowerPC.

Can you do a ninja clean and then rebuild?

Thanks,

–Doru

[ikitayama]

Doru,
Thanks. I obtained libomp.a successfully from the build, however, I am not getting offload libraries with
the configuration below:

cmake -G “Ninja” -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$PROJECT/pcp0151/opt/clang-ykt -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ -DLLVM_TARGETS_TO_BUILD=PowerPC -DLIBOMP_ENABLE_SHARED=FALSE -DCLANG_OPENMP_NVPTX_DEFAULT_ARCH=sm_60 -DLLVM_TEMPORARILY_ALLOW_OLD_TOOLCHAIN=TRUE -DLIBOMP_ENABLE_SHARED=FALSE /tmp/projects/clang-ykt

Itaru.

[ikitayama]

Doru,
I have updated the repositories (clang and openmp) placed under clang-ykt to today’s HEAD
and built it without an issue on PowerPC. I confirmed libomp.a in the destination lib directory.

Thanks,
Itaru.