FindCUDAToolkit: Factor out discovery code into a separate file

This allows for re-use in other parts of the code, that require the CUDA
toolkit location, but can't or may not want to use the full
`FindCUDAToolkit`.

1 files changed, 225 insertions, 0 deletions

diff --git a/Modules/Internal/CUDAToolkit.cmake b/Modules/Internal/CUDAToolkit.cmake
new file mode 100644
index 0000000..ab1e568
--- /dev/null
+++ b/Modules/Internal/CUDAToolkit.cmake
@@ -0,0 +1,225 @@
+# Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+# file Copyright.txt or https://cmake.org/licensing for details.
+
+# This file is for sharing code for finding basic CUDA toolkit information between
+# CMakeDetermineCUDACompiler.cmake and FindCUDAToolkit.cmake.
+
+# For NVCC we can easily deduce the SDK binary directory from the compiler path.
+if(CMAKE_CUDA_COMPILER_LOADED AND NOT CUDAToolkit_BIN_DIR AND CMAKE_CUDA_COMPILER_ID STREQUAL "NVIDIA")
+  get_filename_component(cuda_dir "${CMAKE_CUDA_COMPILER}" DIRECTORY)
+  set(CUDAToolkit_BIN_DIR "${cuda_dir}" CACHE PATH "")
+  mark_as_advanced(CUDAToolkit_BIN_DIR)
+  unset(cuda_dir)
+endif()
+
+# Try language- or user-provided path first.
+if(CUDAToolkit_BIN_DIR)
+  find_program(CUDAToolkit_NVCC_EXECUTABLE
+    NAMES nvcc nvcc.exe
+    PATHS ${CUDAToolkit_BIN_DIR}
+    NO_DEFAULT_PATH
+    )
+endif()
+
+# Search using CUDAToolkit_ROOT
+find_program(CUDAToolkit_NVCC_EXECUTABLE
+  NAMES nvcc nvcc.exe
+  PATHS ENV CUDA_PATH
+  PATH_SUFFIXES bin
+)
+
+# If the user specified CUDAToolkit_ROOT but nvcc could not be found, this is an error.
+if(NOT CUDAToolkit_NVCC_EXECUTABLE AND (DEFINED CUDAToolkit_ROOT OR DEFINED ENV{CUDAToolkit_ROOT}))
+  # Declare error messages now, print later depending on find_package args.
+  set(fail_base "Could not find nvcc executable in path specified by")
+  set(cuda_root_fail "${fail_base} CUDAToolkit_ROOT=${CUDAToolkit_ROOT}")
+  set(env_cuda_root_fail "${fail_base} environment variable CUDAToolkit_ROOT=$ENV{CUDAToolkit_ROOT}")
+
+  if(CUDAToolkit_FIND_REQUIRED)
+    if(DEFINED CUDAToolkit_ROOT)
+      message(FATAL_ERROR ${cuda_root_fail})
+    elseif(DEFINED ENV{CUDAToolkit_ROOT})
+      message(FATAL_ERROR ${env_cuda_root_fail})
+    endif()
+  else()
+    if(NOT CUDAToolkit_FIND_QUIETLY)
+      if(DEFINED CUDAToolkit_ROOT)
+        message(STATUS ${cuda_root_fail})
+      elseif(DEFINED ENV{CUDAToolkit_ROOT})
+        message(STATUS ${env_cuda_root_fail})
+      endif()
+    endif()
+    set(CUDAToolkit_FOUND FALSE)
+    unset(fail_base)
+    unset(cuda_root_fail)
+    unset(env_cuda_root_fail)
+    return()
+  endif()
+endif()
+
+# CUDAToolkit_ROOT cmake / env variable not specified, try platform defaults.
+#
+# - Linux: /usr/local/cuda-X.Y
+# - macOS: /Developer/NVIDIA/CUDA-X.Y
+# - Windows: C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\vX.Y
+#
+# We will also search the default symlink location /usr/local/cuda first since
+# if CUDAToolkit_ROOT is not specified, it is assumed that the symlinked
+# directory is the desired location.
+if(NOT CUDAToolkit_NVCC_EXECUTABLE)
+  if(UNIX)
+    if(NOT APPLE)
+      set(platform_base "/usr/local/cuda-")
+    else()
+      set(platform_base "/Developer/NVIDIA/CUDA-")
+    endif()
+  else()
+    set(platform_base "C:\\Program Files\\NVIDIA GPU Computing Toolkit\\CUDA\\v")
+  endif()
+
+  # Build out a descending list of possible cuda installations, e.g.
+  file(GLOB possible_paths "${platform_base}*")
+  # Iterate the glob results and create a descending list.
+  set(possible_versions)
+  foreach (p ${possible_paths})
+    # Extract version number from end of string
+    string(REGEX MATCH "[0-9][0-9]?\\.[0-9]$" p_version ${p})
+    if(IS_DIRECTORY ${p} AND p_version)
+      list(APPEND possible_versions ${p_version})
+    endif()
+  endforeach()
+
+  # Cannot use list(SORT) because that is alphabetical, we need numerical.
+  # NOTE: this is not an efficient sorting strategy.  But even if a user had
+  # every possible version of CUDA installed, this wouldn't create any
+  # significant overhead.
+  set(versions)
+  foreach (v ${possible_versions})
+    list(LENGTH versions num_versions)
+    # First version, nothing to compare with so just append.
+    if(num_versions EQUAL 0)
+      list(APPEND versions ${v})
+    else()
+      # Loop through list.  Insert at an index when comparison is
+      # VERSION_GREATER since we want a descending list.  Duplicates will not
+      # happen since this came from a glob list of directories.
+      set(i 0)
+      set(early_terminate FALSE)
+      while (i LESS num_versions)
+        list(GET versions ${i} curr)
+        if(v VERSION_GREATER curr)
+          list(INSERT versions ${i} ${v})
+          set(early_terminate TRUE)
+          break()
+        endif()
+        math(EXPR i "${i} + 1")
+      endwhile()
+      # If it did not get inserted, place it at the end.
+      if(NOT early_terminate)
+        list(APPEND versions ${v})
+      endif()
+    endif()
+  endforeach()
+
+  # With a descending list of versions, populate possible paths to search.
+  set(search_paths)
+  foreach (v ${versions})
+    list(APPEND search_paths "${platform_base}${v}")
+  endforeach()
+
+  # Force the global default /usr/local/cuda to the front on Unix.
+  if(UNIX)
+    list(INSERT search_paths 0 "/usr/local/cuda")
+  endif()
+
+  # Now search for nvcc again using the platform default search paths.
+  find_program(CUDAToolkit_NVCC_EXECUTABLE
+    NAMES nvcc nvcc.exe
+    PATHS ${search_paths}
+    PATH_SUFFIXES bin
+  )
+
+  # We are done with these variables now, cleanup for caller.
+  unset(platform_base)
+  unset(possible_paths)
+  unset(possible_versions)
+  unset(versions)
+  unset(i)
+  unset(early_terminate)
+  unset(search_paths)
+
+  if(NOT CUDAToolkit_NVCC_EXECUTABLE)
+    if(CUDAToolkit_FIND_REQUIRED)
+      message(FATAL_ERROR "Could not find nvcc, please set CUDAToolkit_ROOT.")
+    elseif(NOT CUDAToolkit_FIND_QUIETLY)
+      message(STATUS "Could not find nvcc, please set CUDAToolkit_ROOT.")
+    endif()
+
+    set(CUDAToolkit_FOUND FALSE)
+    return()
+  endif()
+endif()
+
+if(NOT CUDAToolkit_BIN_DIR AND CUDAToolkit_NVCC_EXECUTABLE)
+  get_filename_component(cuda_dir "${CUDAToolkit_NVCC_EXECUTABLE}" DIRECTORY)
+  set(CUDAToolkit_BIN_DIR "${cuda_dir}" CACHE PATH "" FORCE)
+  mark_as_advanced(CUDAToolkit_BIN_DIR)
+  unset(cuda_dir)
+endif()
+
+get_filename_component(CUDAToolkit_ROOT_DIR ${CUDAToolkit_BIN_DIR} DIRECTORY ABSOLUTE)
+
+# Handle cross compilation
+if(CMAKE_CROSSCOMPILING)
+  if(CMAKE_SYSTEM_PROCESSOR STREQUAL "armv7-a")
+    # Support for NVPACK
+    set(CUDAToolkit_TARGET_NAME "armv7-linux-androideabi")
+  elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "arm")
+    # Support for arm cross compilation
+    set(CUDAToolkit_TARGET_NAME "armv7-linux-gnueabihf")
+  elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "aarch64")
+    # Support for aarch64 cross compilation
+    if(ANDROID_ARCH_NAME STREQUAL "arm64")
+      set(CUDAToolkit_TARGET_NAME "aarch64-linux-androideabi")
+    else()
+      set(CUDAToolkit_TARGET_NAME "aarch64-linux")
+    endif(ANDROID_ARCH_NAME STREQUAL "arm64")
+  elseif(CMAKE_SYSTEM_PROCESSOR STREQUAL "x86_64")
+      set(CUDAToolkit_TARGET_NAME "x86_64-linux")
+  endif()
+
+  if(EXISTS "${CUDAToolkit_ROOT_DIR}/targets/${CUDAToolkit_TARGET_NAME}")
+    set(CUDAToolkit_TARGET_DIR "${CUDAToolkit_ROOT_DIR}/targets/${CUDAToolkit_TARGET_NAME}")
+    # add known CUDA target root path to the set of directories we search for programs, libraries and headers
+    list(PREPEND CMAKE_FIND_ROOT_PATH "${CUDAToolkit_TARGET_DIR}")
+
+    # Mark that we need to pop the root search path changes after we have
+    # found all cuda libraries so that searches for our cross-compilation
+    # libraries work when another cuda sdk is in CMAKE_PREFIX_PATH or
+    # PATh
+    set(_CUDAToolkit_Pop_ROOT_PATH True)
+  endif()
+else()
+  # Not cross compiling
+  set(CUDAToolkit_TARGET_DIR "${CUDAToolkit_ROOT_DIR}")
+  # Now that we have the real ROOT_DIR, find components inside it.
+  list(APPEND CMAKE_PREFIX_PATH ${CUDAToolkit_ROOT_DIR})
+
+  # Mark that we need to pop the prefix path changes after we have
+  # found the cudart library.
+  set(_CUDAToolkit_Pop_Prefix True)
+endif()
+
+# Find the include/ directory
+find_path(CUDAToolkit_INCLUDE_DIR
+  NAMES cuda_runtime.h
+)
+
+# Find a tentative CUDAToolkit_LIBRARY_DIR. FindCUDAToolkit overrides it by searching for the CUDA runtime,
+# but we can't do that here, as CMakeDetermineCUDACompiler wants to use it before the variables necessary
+# for find_library() have been initialized.
+if(EXISTS "${CUDAToolkit_TARGET_DIR}/lib64")
+  set(CUDAToolkit_LIBRARY_DIR "${CUDAToolkit_TARGET_DIR}/lib64")
+elseif(EXISTS "${CUDAToolkit_TARGET_DIR}/lib")
+  set(CUDAToolkit_LIBRARY_DIR "${CUDAToolkit_TARGET_DIR}/lib")
+endif()