build: Switch from FindCUDA to FindCUDAToolkit (#2072)

FindCUDA is obsolete.  FindCUDAToolkit was added in CMake 3.17.  Current cmake_minimum_required is already 3.19.

Signed-off-by: Mark Leone <mleone@nvidia.com>

Author: MarkLeone

src/cmake/externalpackages.cmake

@@ -118,14 +118,42 @@ if (OSL_USE_OPTIX)
             message (STATUS "CUDA_TOOLKIT_ROOT_DIR = ${CUDA_TOOLKIT_ROOT_DIR}")
         endif ()
 
-        checked_find_package (CUDA REQUIRED
+        if (CUDA_TOOLKIT_ROOT_DIR)
+            set (CUDAToolkit_ROOT "${CUDA_TOOLKIT_ROOT_DIR}")
+        endif ()
+
+        checked_find_package (CUDAToolkit REQUIRED
                              VERSION_MIN 9.0
                              RECOMMEND_MIN 11.0
                              RECOMMEND_MIN_REASON
                                 "We don't actively test CUDA older than 11"
-                             PRINT CUDA_INCLUDES)
-        set (CUDA_INCLUDES ${CUDA_TOOLKIT_ROOT_DIR}/include)
-        include_directories (BEFORE "${CUDA_INCLUDES}")
+                             PRINT CUDAToolkit_INCLUDE_DIRS CUDAToolkit_NVCC_EXECUTABLE)
+
+        # Compatibility bridge: legacy CUDA variables.
+        set (CUDA_FOUND ${CUDAToolkit_FOUND})
+        set (CUDA_VERSION ${CUDAToolkit_VERSION})
+        set (CUDA_INCLUDES ${CUDAToolkit_INCLUDE_DIRS})
+        if (CUDA_INCLUDES)
+            list (GET CUDA_INCLUDES 0 CUDA_INCLUDES)
+        endif ()
+
+        # Derive the root dir.  See https://cmake.org/cmake/help/latest/module/FindCUDAToolkit.html
+        if (CUDAToolkit_LIBRARY_ROOT)
+            set (CUDA_TOOLKIT_ROOT_DIR "${CUDAToolkit_LIBRARY_ROOT}")
+        elseif (CUDAToolkit_TARGET_DIR)
+            set (CUDA_TOOLKIT_ROOT_DIR "${CUDAToolkit_TARGET_DIR}")
+        elseif (CUDAToolkit_BIN_DIR)
+            get_filename_component (CUDA_TOOLKIT_ROOT_DIR "${CUDAToolkit_BIN_DIR}" DIRECTORY)
+        endif ()
+        if (NOT CUDA_TOOLKIT_ROOT_DIR)
+            message (FATAL_ERROR "Could not determine CUDA toolkit root directory.")
+        endif ()
+
+        if (CUDAToolkit_NVCC_EXECUTABLE)
+            set (CUDA_NVCC_EXECUTABLE "${CUDAToolkit_NVCC_EXECUTABLE}")
+        else ()
+            find_program (CUDA_NVCC_EXECUTABLE NAMES nvcc HINTS "${CUDA_TOOLKIT_ROOT_DIR}/bin")
+        endif ()
 
         STRING (FIND ${LLVM_TARGETS} "NVPTX" nvptx_index)
         if (NOT ${nvptx_index} GREATER -1)
@@ -138,7 +166,11 @@ if (OSL_USE_OPTIX)
         # suffixes earlier in the suffix list. Don't forget to restore after
         # so that this only applies to these library searches right here.
         set (save_lib_path ${CMAKE_FIND_LIBRARY_SUFFIXES})
-        if (CUDA_PREFER_STATIC_LIBS)
+        if (CUDA_PREFER_STATIC_LIBS AND TARGET CUDA::cudart_static)
+            set (cudart_lib CUDA::cudart_static)
+        elseif (TARGET CUDA::cudart)
+            set (cudart_lib CUDA::cudart)
+        elseif (CUDA_PREFER_STATIC_LIBS)
             set (CMAKE_FIND_LIBRARY_SUFFIXES .lib .a ${CMAKE_FIND_LIBRARY_SUFFIXES})
             find_library(cudart_lib REQUIRED
                          NAMES cudart_static cudart
@@ -148,7 +180,6 @@ if (OSL_USE_OPTIX)
                          NAMES cudart
                          PATHS "${CUDA_TOOLKIT_ROOT_DIR}/lib64" "${CUDA_TOOLKIT_ROOT_DIR}/x64" "${CUDA_TOOLKIT_ROOT_DIR}/lib/x64")
         endif ()
-        # Is it really a good idea to completely reset CUDA_LIBRARIES here?
         set(CUDA_LIBRARIES ${cudart_lib})
         set(CUDA_EXTRA_LIBS ${CUDA_EXTRA_LIBS} dl rt)
         set (CMAKE_FIND_LIBRARY_SUFFIXES ${save_lib_path})

testsuite/example-cuda/CMakeLists.txt

@@ -2,7 +2,7 @@
 # SPDX-License-Identifier: BSD-3-Clause
 # https://github.com/AcademySoftwareFoundation/OpenShadingLanguage
 
-cmake_minimum_required(VERSION 3.15)
+cmake_minimum_required(VERSION 3.19)  # Same as top-level CMakeLists.txt
 project(examplecuda LANGUAGES CXX)
 
 if (NOT CMAKE_BUILD_TYPE)
@@ -19,12 +19,16 @@ include(check_is_enabled)
 include(checked_find_package)
 
 find_package(OSL REQUIRED)
-find_package(CUDA REQUIRED)
+find_package(CUDAToolkit REQUIRED)
 checked_find_package(LLVM 7.0 REQUIRED)
 checked_find_package(Imath 3.1 REQUIRED)
 checked_find_package(OpenImageIO 2.4 REQUIRED)
 checked_find_package(OptiX REQUIRED)
 
+set(CUDA_TOOLKIT_ROOT_DIR ${CUDAToolkit_ROOT_DIR})
+set(CUDA_INCLUDE_DIRS ${CUDAToolkit_INCLUDE_DIRS})
+set(CUDA_NVCC_EXECUTABLE ${CUDAToolkit_NVCC_EXECUTABLE})
+set(CUDA_LIBRARIES CUDA::cudart)
 
 # Make the build area layout look like we expect
 set (CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
@@ -34,13 +38,37 @@ set (CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)
 # TODO: what are the path suffixes on other platforms?
 find_library(CUDA_nvrtc_LIBRARY nvrtc HINTS ${CUDA_TOOLKIT_ROOT_DIR} PATH_SUFFIXES lib lib64)
 find_library(CUDA_cuda_LIBRARY cuda HINTS ${CUDA_TOOLKIT_ROOT_DIR} PATH_SUFFIXES lib/stubs lib64/stubs)
+if (TARGET CUDA::nvrtc)
+    set(CUDA_nvrtc_LIBRARY CUDA::nvrtc)
+endif ()
+if (TARGET CUDA::cuda_driver)
+    set(CUDA_cuda_LIBRARY CUDA::cuda_driver)
+endif ()
 
 # TODO: move to sm_60?
 set(CUDA_TARGET_ARCH sm_35)
 
 set (CMAKE_CXX_STANDARD 17 CACHE STRING
      "C++ standard to build with (17, 20, etc.)")
 
+# Compile a CUDA source file to PTX with NVCC.  (Formerly provided by FindCUDA.cmake)
+function(cuda_compile_ptx out_var cuda_src)
+    cmake_parse_arguments(_ccp "" "" "OPTIONS" ${ARGN})
+    get_filename_component(cuda_src_we ${cuda_src} NAME_WE)
+    set(cuda_ptx "${CMAKE_CURRENT_BINARY_DIR}/${cuda_src_we}.ptx")
+    add_custom_command(OUTPUT ${cuda_ptx}
+        COMMAND ${CUDA_NVCC_EXECUTABLE}
+                ${_ccp_OPTIONS}
+                -ptx
+                ${cuda_src}
+                -o ${cuda_ptx}
+        MAIN_DEPENDENCY ${cuda_src}
+        DEPENDS ${cuda_src}
+        WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
+    )
+    set(${out_var} ${cuda_ptx} PARENT_SCOPE)
+endfunction()
+
 # Compile our "renderer" to PTX
 cuda_compile_ptx(CUDA_PTX_FILES cuda_grid_renderer.cu
     OPTIONS --gpu-architecture=${CUDA_TARGET_ARCH} --use_fast_math -dc