Linking of CUDA library in CMake

Question

I am using CMake 3.10 and have a problem linking a compiled library to a test executable in CMake. I searched a lot and found that in earlier versions there was a problem where you could not link intermediate libraries in the result executable. I was not able to tell if this was resolved or still an issue.

My CMake files look like this:

Algo:

cmake_minimum_required (VERSION 3.9)
project(${MODULE_NAME}_core LANGUAGES CXX CUDA)


add_subdirectory("${core_impl_dir}" implementation)


set(cuda_src "parallel/ParallelComputation.cu")
set(cuda_hdr "parallel/ParallelComputation.h")

add_library(${PROJECT_NAME} STATIC "${cuda_src}" "${cuda_hdr}"
)


target_include_directories (${PROJECT_NAME} PUBLIC "include/" 
"parallel/"
)

source_group("parallel"  FILES "${cuda_src}" "${cuda_hdr}")


set_property(TARGET ${PROJECT_NAME} PROPERTY FOLDER ${MODULE_NAME})

Test:

project(${MODULE_NAME}_gtest LANGUAGES CXX CUDA)

add_subdirectory("${gtest_impl_dir}" implementation)

add_executable(${PROJECT_NAME} "${gtest_impl_src}")
target_link_libraries(${PROJECT_NAME} ${MODULE_NAME}_core)

enable_testing()
find_package(GTest REQUIRED)
include_directories("${GTEST_INCLUDE_DIRS}")


target_link_libraries(${PROJECT_NAME} ${GTEST_BOTH_LIBRARIES})

source_group("Implementation\\Source Files" FILES "${gtest_impl_src}" )

set_property(TARGET ${PROJECT_NAME} PROPERTY FOLDER ${MODULE_NAME})

add_test(${PROJECT_NAME} ${PROJECT_NAME})

Building just Algo works fine, but when also building Test, I get linking errors, for example

../implementation/libmatrix1_testCuda_core.a(ParallelComputation.cu.o): In Funktion 'cudaError cudaMalloc(float**, unsigned long)': tmpxft_00005ad0_00000000-5_ParallelComputation.cudafe1.cpp:(.text+0x4f2): Undefined reference 'cudaMalloc'

EDIT using make VERBOSE=1 I got this linking command:

/usr/bin/c++ -Wl,--no-as-needed -pthread -g -std=c++14 -Wall
CMakeFiles/matrix1_testCuda_gtest.dir//tests/eclipseProject/algos/testCuda/test/src/main.cpp.o CMakeFiles/matrix1_testCuda_gtest.dir/cmake_device_link.o -o matrix1_testCuda_gtest ../implementation/libmatrix1_testCuda_core.a /usr/lib/libgtest.a /usr/lib/libgtest_main.a

Answer 1

I got this to work by calling

find_package(CUDA 9.0 REQUIRED)

in both CMake files. Also, in the Algo file (which contains the device code), I had to do

target_link_libraries(${PROJECT_NAME} ${CUDA_LIBRARIES})

I was expecting that the language support for CUDA would make those steps unnecessary, but apparently not.

Answer 2

I just ran into something very similar to this where the root problem was that most of my binary was being compiled with my system cxx compiler, and the cuda bits were being compiled with the cuda gcc compiler (9.1 for system, 8.3 for cuda).

Surprisingly it was fixed by changing:

project(MyProject LANGUAGES CXX CUDA)

to

project(MyProject LANGUAGES CUDA CXX)

After that change, CMake picked up the cuda version of the gcc compiler as the main compiler, and my binary started building again. I'm not sure if this could introduce problems for other packages, but it fixed the linking problem I was hitting.