Adding install capability

[yasahi-hpc]

In this PR, I am trying to add install capability for KokkosFFT.
The test code (install_test/main.cpp) using the KokkosFFT as installed library fails since Kokkos not found is raised in KokkosFFTConfig.cmake.
Once succeeded, I need to add a GitHub action for this test.

Installation of KokkosFFT for SKX

mkdir build && cd build
cmake -DBUILD_TESTING=OFF -DCMAKE_CXX_COMPILER=icpx -DCMAKE_BUILD_TYPE=RelWithDebInfo -DKokkos_ENABLE_OPENMP=ON -DKokkos_ARCH_SKX=ON -DCMAKE_INSTALL_PREFIX=${KokkosFFT_Install_dir}/install ..
make install

Build testing of test code (configure fails)

export KokkosFFT_DIR=${KokkosFFT_Install_dir}/install/include
cd ..
mkdir -p install_test/build && cd install_test/build
cmake -DCMAKE_CXX_COMPILER=icpx -DCMAKE_BUILD_TYPE=Release -DKokkos_ENABLE_OPENMP=ON -DKokkos_ARCH_SKX=ON ..

[yasahi-hpc]

I guess I made some mistakes, but Kokkos_FOUND is set False when installed. Thus, KokkosFFT_Found also becomes False. I would appreciate it if some of you could comment on this PR. @jbigot @cedricchevalier19

[cedricchevalier19]

Some minor issues to solve. I will be happy to look again at these aspects.

[cedricchevalier19]

I think your issue with the install test is here: when building your library if you do not find an external Kokkos you build one and you do not install it.
Install test should be performed with an already available Kokkos installation.

[yasahi-hpc]

That is true. With the modifications, local install test worked if Kokkos is already installed. If Kokkos is not installed, it would still fail

[cedricchevalier19]

I do not think you need this flag. Install test should more likely run by CI.

[yasahi-hpc]

Makes sense. Modified accordingly

[cedricchevalier19]

Suggested change

	@PACKAGE_INIT@
	include(CMakeFindDependencyMacro)
	find_dependency(Kokkos)
	include(${CMAKE_CURRENT_LIST_DIR}/KokkosFFT-targets.cmake)
	check_required_components(KokkosFFT)
	@PACKAGE_INIT@
	# Set and Check must go first else macro might be redefined by find_dependency ...
	set_and_check(KokkosFFT_TARGET_FILE "${PACKAGE_PREFIX_DIR}/@config_install_dir@/@[email protected]")
	include(CMakeFindDependencyMacro)
	find_dependency(Kokkos)
	include(${KokkosFFT_TARGET_FILE})
	check_required_components(KokkosFFT)

And define required variable in the CMakeLists.txt before calling configure_package_config_file.

[yasahi-hpc]

For some reason,

set_and_check(KokkosFFT_TARGET_FILE "${PACKAGE_PREFIX_DIR}/@config_install_dir@/@[email protected]")

this line did not work appropriately. @config_install_dir@ and @KokkosFFT_EXPORT_TARGET@ are empty.

Thus, I did like this

set_and_check(KokkosFFT_TARGET_FILE
 "${PACKAGE_PREFIX_DIR}/include/KokkosFFT-targets.cmake")

I also added dependency to fft libraries.

[cedricchevalier19]

You have to define config_install_dir and KokkosFFT_EXPORT_TARGET variables in the CMakeLists.txt before calling configure_file.

I still think include is not a good idea to install *.cmake files.

[yasahi-hpc]

@cedricchevalier19 Firstly, thank you for the comments.

Sure, I will set the configure_install_dir and KokkosFFT_EXPORT_TARGET.
Yes, in the current configuration under <install_path> would look like this

<install_path>/
  |—include/
  |        |--CMakeLists.txt 
  |        |--FindFFTW.cmake
  |        |--KokkosFFT-targets.cmake
  |        |--src
  |        └--unit_test
  └─lib64
      └─cmake
          └─kokkos-fft
                 |--KokkosFFTConfig.cmake 
                 └--KokkosFFTConfigVersion.cmake

Should it be something like this?

<install_path>/
  |—include/    
  |       └-*hpp
  |        
  └─lib64
      └─cmake
          └─kokkos-fft
                 |--FindFFTW.cmake
                 |--KokkosFFT-targets.cmake
                 |--KokkosFFTConfig.cmake 
                 └--KokkosFFTConfigVersion.cmake

I feel that CMakeLists.txt and unit_test under include are unnecessary and headers under src should be directly placed under include

[yasahi-hpc]

@cedricchevalier19 Thanks a lot for your comment! I will give it a try to fix the issues.

[yasahi-hpc]

Some minor issues to solve. I will be happy to look again at these aspects.

@cedricchevalier19 Hello, re-reviews are highly appreciated. If it is OK, I will implement CI for installation

[yasahi-hpc]

@cedricchevalier19 Firstly, I would like to add CIs. After that, I will update CMake based on your comments.

[yasahi-hpc]

@cedricchevalier19 Since most of issues are fixed, I will merge this PR. Any comments or suggestions are still welcome. Thank you again for your help.