CUDA.cmake

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if(CUDA_COMPILER MATCHES "[Cc]lang")
  set(BYTELLM_NATIVE_CUDA_INIT ON)
elseif(CMAKE_VERSION VERSION_LESS 3.12.4)
  set(BYTELLM_NATIVE_CUDA_INIT OFF)
else()
  set(BYTELLM_NATIVE_CUDA_INIT ON)
endif()

set(BYTELLM_NATIVE_CUDA ${BYTELLM_NATIVE_CUDA_INIT} CACHE BOOL "Utilize the CMake native CUDA flow")

if(NOT DEFINED ENV{CUDACXX} AND NOT DEFINED ENV{CUDA_BIN_PATH} AND DEFINED ENV{CUDA_PATH})
  # For backward compatibility, allow use of CUDA_PATH.
  set(ENV{CUDACXX} $ENV{CUDA_PATH}/bin/nvcc)
endif()

if(BYTELLM_NATIVE_CUDA)
  message(STATUS "Using BYTELLM_NATIVE_CUDA")
  enable_language(CUDA)
  if(NOT CUDA_VERSION)
    set(CUDA_VERSION ${CMAKE_CUDA_COMPILER_VERSION})
  endif()
  if(NOT CUDA_TOOLKIT_ROOT_DIR)
    get_filename_component(CUDA_TOOLKIT_ROOT_DIR "${CMAKE_CUDA_COMPILER}/../.." ABSOLUTE)
  endif()

else()
  find_package(CUDA REQUIRED)
  # We workaround missing variables with the native flow by also finding the CUDA toolkit the old way.
  if(NOT CMAKE_CUDA_COMPILER_VERSION)
    set(CMAKE_CUDA_COMPILER_VERSION ${CUDA_VERSION})
  endif()

endif()

if (CUDA_VERSION VERSION_LESS 10.2)
  message(FATAL_ERROR "CUDA 10.2+ Required, Found ${CUDA_VERSION}.")
endif()
if(NOT BYTELLM_NATIVE_CUDA OR CUDA_COMPILER MATCHES "[Cc]lang")
  set(CMAKE_CUDA_COMPILER ${CUDA_TOOLKIT_ROOT_DIR}/bin/nvcc)
  message(STATUS "CUDA Compiler: ${CMAKE_CUDA_COMPILER}")
endif()