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build: Switch from FindCUDA to FindCUDAToolkit (#2072) #2073

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43 changes: 37 additions & 6 deletions src/cmake/externalpackages.cmake
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Original file line number Diff line number Diff line change
Expand Up @@ -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)
Comment on lines +141 to +146
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CUDA_TOOLKIT_ROOT_DIR is later treated as a full toolkit root (used for --cuda-path=..., .../bin nvcc lookup, and .../lib64 paths). Setting it from CUDAToolkit_LIBRARY_ROOT can be inconsistent with those uses on toolkits where the library root is not the same as the toolkit root. Consider preferring CUDAToolkit_TARGET_DIR (or deriving from CUDAToolkit_BIN_DIR) for CUDA_TOOLKIT_ROOT_DIR, and using CUDAToolkit_LIBRARY_ROOT only for library searches.

Suggested change
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 "${CUDAToolkit_BIN_DIR}" DIRECTORY)
if (CUDAToolkit_TARGET_DIR)
set (CUDA_TOOLKIT_ROOT_DIR "${CUDAToolkit_TARGET_DIR}")
elseif (CUDAToolkit_BIN_DIR)
get_filename_component (CUDA_TOOLKIT_ROOT_DIR "${CUDAToolkit_BIN_DIR}" DIRECTORY)
elseif (CUDAToolkit_LIBRARY_ROOT)
# Fallback: library root may not always equal the full toolkit root,
# but is used here as a last-resort compatibility measure.
set (CUDA_TOOLKIT_ROOT_DIR "${CUDAToolkit_LIBRARY_ROOT}")

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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)
Expand All @@ -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 ${CMAKE_FIND_LIBRARY_SUFFIXES})
find_library(cudart_lib REQUIRED
NAMES cudart_static cudart
Expand All @@ -148,7 +180,6 @@ if (OSL_USE_OPTIX)
NAMES cudart
PATHS "${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})
Expand Down
32 changes: 30 additions & 2 deletions testsuite/example-cuda/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand All @@ -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})
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CUDAToolkit_ROOT_DIR doesn’t appear to be set anywhere in this repo and is not one of the variables exposed/used elsewhere for FindCUDAToolkit. As written, CUDA_TOOLKIT_ROOT_DIR will likely be empty, which then defeats the find_library(... HINTS ${CUDA_TOOLKIT_ROOT_DIR} ...) calls below. Consider deriving the toolkit root from CUDAToolkit_TARGET_DIR / CUDAToolkit_BIN_DIR (parent dir) / CUDAToolkit_LIBRARY_ROOT (if appropriate), similar to the logic used in src/cmake/externalpackages.cmake.

Suggested change
set(CUDA_TOOLKIT_ROOT_DIR ${CUDAToolkit_ROOT_DIR})
# Derive a usable CUDA toolkit root directory from CUDAToolkit variables.
set(CUDA_TOOLKIT_ROOT_DIR "")
if (CUDAToolkit_LIBRARY_ROOT)
# Use the library root directly when available.
set(CUDA_TOOLKIT_ROOT_DIR "${CUDAToolkit_LIBRARY_ROOT}")
elseif (CUDAToolkit_BIN_DIR)
# Fall back to the parent of the bin directory.
get_filename_component(CUDA_TOOLKIT_ROOT_DIR "${CUDAToolkit_BIN_DIR}" DIRECTORY)
elseif (CUDAToolkit_ROOT)
# As a last resort, use the generic CUDAToolkit root, if defined.
set(CUDA_TOOLKIT_ROOT_DIR "${CUDAToolkit_ROOT}")
endif ()

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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)
Expand All @@ -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
Comment on lines +59 to +62
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cuda_compile_ptx() invokes ${CUDA_NVCC_EXECUTABLE}, but CUDAToolkit_NVCC_EXECUTABLE may be unset on systems that have CUDA runtime libraries/headers but no nvcc installed. Add a configure-time fallback/check (e.g., find_program(CUDA_NVCC_EXECUTABLE NAMES nvcc ...) and message(FATAL_ERROR ...) if still not found) so this fails during configuration rather than at build time.

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${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
Expand Down