Fix the CMAKE error (mentioned in the README.md)

[yuang-chen]

"error: undefined reference to '__cudaRegisterLinkedBinary_12_spmm_cpp1_ii_handle'"

This error can be fixed by using more recent syntax to write the CMakeLists.txt.

• CMakeLists.txt in the root folder:

cmake_minimum_required (VERSION 3.22)
project (tSparse)

set(tSparse_VERSION_MAJOR 0)
set(tSparse_VERSION_MINOR 4)

enable_language(CUDA CXX)
set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CUDA_STANDARD 17)
set(CMAKE_CUDA_ARCHITECTURES 80)
set(CUDA_SEPARABLE_COMPILATION ON)
set(CUDA_PROPAGATE_HOST_FLAGS ON)

find_package(OpenMP REQUIRED)
find_package(CUDAToolkit REQUIRED)

include_directories( ${CMAKE_SOURCE_DIR}/external )

add_subdirectory(src)

• CMakeLists.txt in the src folder:

project (SpGEMM)

add_executable(spmm spmm.cu mm.cu)

# Set compiler options using generator expressions for different configurations
target_compile_options(spmm PRIVATE 
    $<$<COMPILE_LANGUAGE:CUDA>: 
        $<$<CONFIG:Debug>:-g -G -O0>  # Flags for Debug build
        $<$<CONFIG:Release>:-O3>     # Flags for Release build
        -Xcompiler=-fopenmp           # OpenMP flags for CUDA compiler
        --extended-lambda 
        --expt-relaxed-constexpr 
        -lineinfo
    >
)

target_link_libraries(spmm PRIVATE OpenMP::OpenMP_CXX CUDA::cusparse)