[CMake] Using CMake to link C++ and CUDA Object file

[Robert Maynard]

if you are using the new first class cuda language, as seen by `project(MyTest
LANGUAGES CXX CUDA)` you shouldn't use the old find cuda package or the
associated cuda_add_library calls. When using the first class cuda language
simply use add_library.

The other difference I notice is that you makefile example is not building
shared libraries but object files, so to the same in CMake you need to use
'add_library' with the OBJECT keyword not the SHARED keyword.



On Fri, Jul 6, 2018 at 12:01 AM Quang Ha <quang.t.ha.20 at gmail.com> wrote:

> Hi all,
>
> Following upon how to perform code linking between CUDA and C++ (here at
> https://devblogs.nvidia.com/separate-compilation-linking-cuda-device-code/),
> I have successfully come up with a Makefile that is currently working for
> my test case:
>
> ##################################Makefile###############
> ##################################
> main_objects = main.o
> host_objects = host.o
> device_objects = device.o
>
> all: $(main_objects) $(host_objects) $(device_objects)
>         g++ -O3 -fopenmp $(main_objects) $(host_objects) $(device_objects)
> -L/usr/local/cuda/lib64 -lcudart -o main
>
> $(main_objects): $(main_objects:.o=.cpp)
>         g++ -O3 -I/usr/local/cuda/include -c $< -o $@
>
> $(host_objects): $(host_objects:.o=.cpp)
>         g++ -O3 -DTHRUST_HOST_SYSTEM=THRUST_HOST_SYSTEM_OMP -fopenmp -c $<
> -o $@
>
> $(device_objects): $(device_objects:.o=.cu)
>         nvcc -O3 -DTHRUST_DEVICE_SYSTEM=THRUST_DEVICE_SYSTEM_CUDA -c $< -o
> $@
>
> clean:
>         rm -f *.o main
> ####################################################################
> ##################################
>
> Now, I am trying to write a CMake for this, my current attempt is as
> followed:
>
>
> ##############################################CMakeLists.txt############################################
> cmake_minimum_required(VERSION 3.8)
> project(MyTest LANGUAGES CXX CUDA)
>
> # check requirements
> find_package(CUDA REQUIRED)
> find_package(OpenMP)
>
> if (CUDA_FOUND AND OPENMP_FOUND)
>     # OpenMP
>     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${OpenMP_C_FLAGS}")
>     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}")
>     set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS}
> ${OpenMP_EXE_LINKER_FLAGS}")
>
>     # CUDA
>     include_directories(${CUDA_INCLUDE_DIRS})
>     set(ALL_CUDA_LIBS ${CUDA_LIBRARIES} ${CUDA_cusparse_LIBRARY}
> ${CUDA_cublas_LIBRARY})
>     set(LIBS ${LIBS} ${ALL_CUDA_LIBS})
>     set(CUDA_SEPARABLE_COMPILATION OFF)
>     set(CUDA_NVCC_FLAGS ${CUDA_NVCC_FLAGS};--maxrregcount 32)
>
>     set(OMP_SOURCES host.cpp)
>     add_library(Host_OMP SHARED ${OMP_SOURCES})
>     set_target_properties(Host_OMP PROPERTIES COMPILE_FLAGS
> "-DTHRUST_HOST_SYSTEM=THRUST_HOST_SYSTEM_OMP")
>     set(LIBS ${LIBS} ${Host_OMP})
>
>     set(CUDA_SOURCES device.cu)
>     cuda_add_library(Device_CUDA SHARED ${CUDA_SOURCES})
>     set_target_properties(Device_CUDA PROPERTIES COMPILE_FLAGS
> "-DTHRUST_DEVICE_SYSTEM=THRUST_DEVICE_SYSTEM_CUDA")
>     set_target_properties(Device_CUDA PROPERTIES
> CUDA_SEPERABLE_COMPILATION ON)
>     set(LIBS ${LIBS} ${Device_CUDA})
>
>     add_executable(main main.cpp)
>     target_link_libraries(main ${LIBS})
>
> endif(CUDA_FOUND AND OPENMP_FOUND)
> ####################################################################
> ##################################
>
> It is still, unfortunately, not working. If I commented out the
> add_executable line, the object code for Host_OMP and Device_CUDA is
> compiled. I can then use the terminal and link them with main.cpp using gcc
> and generate the executable - i.e. using the final command in the Makefile
> above.
>
> What am I doing wrong here? It seems to be very fundamental, but I can't
> seem to get it right...
>
> Any suggestions would be greatly appreciated!!
>
> Thanks,
> Quang
> --
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