Modernize CMake

[SimeonEhrig]

The CMake is completely modernized. The main targets are

• make cupla installable and findable via cmake find_package()
• make the usage of add_subdirectory() more common
• remove legacy cmake code

Address issue #158

TODO

• [x] setup initial CMakeLists.txt
• [x] remove legacy CMake code
• [x] overwork usage via add_subdirectory
• [x] allow to install cupla and use find_package()
• [x] add CI integration tests
• [x] enable examples
• [x] writing documentation!
• [x] create cupla release branch before this PR is merged

[SimeonEhrig]

@psychocoderHPC Ready for review

[SimeonEhrig]

From the review in our developer meeting today:

• [x] force to build libcupla as archive file -> makes no sense to use shared lib, because libcupla is strongly depend of the build parameter of the project and avoids LD_LIBRARY_PATH problem
• [x] downgrade to CMake 3.18 -> same version like alpaka - we don't use any advantage of CMake 3.19

[psychocoderHPC]

@SimeonEhrig Do you tested this PR with nvcc as CUDA compiler too? I working on moving alpaka 0.7.0 to cupla and integrated your changes. When try to use cmake with CUDA I get

cmake ../cupla -DCMAKE_INSTALL_PREFIX=$HOME/lib/cupla -Dcupla_BUILD_EXAMPLES=ON -DALPAKA_ACC_GPU_CUDA_ENABLE=ON
...
List of compiler flags added by alpaka
device compiler:
    $<$<COMPILE_LANGUAGE:CUDA>:--expt-relaxed-constexpr>;$<$<COMPILE_LANGUAGE:CUDA>:-Xcudafe=--display_error_number>;$<$<COMPILE_LANGUAGE:CUDA>:-Xcudafe=--diag_suppress=esa_on_defaulted_function_ignored>

-- Configuring done
CMake Error in CMakeLists.txt:
  No known features for CUDA compiler

  ""

  version .

[psychocoderHPC]

@SimeonEhrig Do you tested this PR with nvcc as CUDA compiler too? I working on moving alpaka 0.7.0 to cupla and integrated your changes. When try to use cmake with CUDA I get

cmake ../cupla -DCMAKE_INSTALL_PREFIX=$HOME/lib/cupla -Dcupla_BUILD_EXAMPLES=ON -DALPAKA_ACC_GPU_CUDA_ENABLE=ON
...
List of compiler flags added by alpaka
device compiler:
    $<$<COMPILE_LANGUAGE:CUDA>:--expt-relaxed-constexpr>;$<$<COMPILE_LANGUAGE:CUDA>:-Xcudafe=--display_error_number>;$<$<COMPILE_LANGUAGE:CUDA>:-Xcudafe=--diag_suppress=esa_on_defaulted_function_ignored>

-- Configuring done
CMake Error in CMakeLists.txt:
  No known features for CUDA compiler

  ""

  version .

This error happens only with alpaka 0.7.0 so ignore it for now.

[SimeonEhrig]

@SimeonEhrig Do you tested this PR with nvcc as CUDA compiler too? I working on moving alpaka 0.7.0 to cupla and integrated your changes. When try to use cmake with CUDA I get

cmake ../cupla -DCMAKE_INSTALL_PREFIX=$HOME/lib/cupla -Dcupla_BUILD_EXAMPLES=ON -DALPAKA_ACC_GPU_CUDA_ENABLE=ON
...
List of compiler flags added by alpaka
device compiler:
    $<$<COMPILE_LANGUAGE:CUDA>:--expt-relaxed-constexpr>;$<$<COMPILE_LANGUAGE:CUDA>:-Xcudafe=--display_error_number>;$<$<COMPILE_LANGUAGE:CUDA>:-Xcudafe=--diag_suppress=esa_on_defaulted_function_ignored>

-- Configuring done
CMake Error in CMakeLists.txt:
  No known features for CUDA compiler

  ""

  version .

This error happens only with alpaka 0.7.0 so ignore it for now.

We can't ignore alpaka 0.7.0. This PR should become part of cupla 0.4.0 which bases on alpaka 0.7.0.

[psychocoderHPC]

@SimeonEhrig Do you tested this PR with nvcc as CUDA compiler too? I working on moving alpaka 0.7.0 to cupla and integrated your changes. When try to use cmake with CUDA I get

cmake ../cupla -DCMAKE_INSTALL_PREFIX=$HOME/lib/cupla -Dcupla_BUILD_EXAMPLES=ON -DALPAKA_ACC_GPU_CUDA_ENABLE=ON
...
List of compiler flags added by alpaka
device compiler:
    $<$<COMPILE_LANGUAGE:CUDA>:--expt-relaxed-constexpr>;$<$<COMPILE_LANGUAGE:CUDA>:-Xcudafe=--display_error_number>;$<$<COMPILE_LANGUAGE:CUDA>:-Xcudafe=--diag_suppress=esa_on_defaulted_function_ignored>

-- Configuring done
CMake Error in CMakeLists.txt:
  No known features for CUDA compiler

  ""

  version .

This error happens only with alpaka 0.7.0 so ignore it for now.

We can't ignore alpaka 0.7.0. This PR should become part of cupla 0.4.0 which bases on alpaka 0.7.0.

I played a little bit more with the error. If I install alpaka and use -Dcupla_ALPAKA_PROVIDER=external all works fine. It could be that the issue will be solved with https://github.com/Kitware/CMake/commit/a3cafa4237930d1ec1bcbdddc8a9c592e32458ca but this is currently in no release available.

[psychocoderHPC]

I tested the latest master branch from CMake, the issue still exists, therefore something else is wrong :-(

[psychocoderHPC]

We will not merge this PR directly, if #213 is merged this PR will be merged automatically.

[fwyzard]

force to build libcupla as archive file -> makes no sense to use shared lib, because libcupla is strongly depend of the build parameter of the project and avoids LD_LIBRARY_PATH problem

FWIW, in CMSSW we have been building cupla as a shared library, even though we are not using it in production yet. The rationale is that it would be linked to from many different shared libraries, so using a static archive would duplicate it into each shared library that uses it.

[SimeonEhrig]

force to build libcupla as archive file -> makes no sense to use shared lib, because libcupla is strongly depend of the build parameter of the project and avoids LD_LIBRARY_PATH problem

FWIW, in CMSSW we have been building cupla as a shared library, even though we are not using it in production yet. The rationale is that it would be linked to from many different shared libraries, so using a static archive would duplicate it into each shared library that uses it.

Good point. I opened an issue (#218 ) to address your comment.