threading.cmake

if(MULTITHREADING)
    message(STATUS "Multithreading is enabled.")
    add_compile_options(-pthread)
    add_link_options(-pthread)
    if(WASM)
        # Emscripten + pthreads. SHARED_MEMORY is implied by -pthread, but
        # passing it explicitly makes the target memory shape obvious to
        # readers of CMakeCache.txt.
        add_link_options("SHELL:-sSHARED_MEMORY=1")
        # Prevent indirect call type mismatch errors in thread_local destructors
        # (without this the benchmark flow fails at destruction point for WASM)
        add_compile_options(-fno-c++-static-destructors)
    endif()
    #add_compile_options(-fsanitize=thread)
    #add_link_options(-fsanitize=thread)
else()
    message(STATUS "Multithreading is disabled.")
    add_definitions(-DNO_MULTITHREADING)
    set(OMP_MULTITHREADING OFF)
    if(WASM)
        # Single-threaded wasm: bake out the pthread pool entirely. The
        # toolchain enables -pthread by default; we override here.
        add_compile_options(-pthread)
        add_link_options(-pthread)
        add_link_options("SHELL:-sPTHREAD_POOL_SIZE=0")
    endif()
endif()

if(OMP_MULTITHREADING)
    find_package(OpenMP REQUIRED)
    message(STATUS "OMP multithreading is enabled.")
    link_libraries(OpenMP::OpenMP_CXX)
    add_definitions(-DOMP_MULTITHREADING)
else()
    message(STATUS "OMP multithreading is disabled.")
endif()

if(ENABLE_PAR_ALGOS)
    find_package(TBB QUIET OPTIONAL_COMPONENTS tbb)
    if(${TBB_FOUND})
        message(STATUS "std::execution parallel algorithms are enabled.")
        link_libraries(TBB::tbb)
    else()
        message(STATUS "Could not locate Intel TBB, disabling std::execution parallel algorithms.")
        add_definitions(-DNO_PAR_ALGOS)
    endif()
else()
    message(STATUS "std::execution parallel algorithms are disabled.")
    add_definitions(-DNO_PAR_ALGOS)
endif()