Revamp nvml.dll logic.

cmake/NVBenchNVML.cmake

@@ -1,37 +1,43 @@
-# Since this file is installed, we need to make sure that the CUDAToolkit has
-# been found by consumers:
-if (NOT TARGET CUDA::toolkit)
-  find_package(CUDAToolkit REQUIRED)
-endif()
-
-if (WIN32)
-  # The CUDA:: targets currently don't provide dll locations through the
-  # `IMPORTED_LOCATION` property, nor are they marked as `SHARED` libraries
-  # (they're currently `UNKNOWN`). This prevents the `nvbench_setup_dep_dlls`
-  # CMake function from copying the dlls to the build / install directories.
-  # This is discussed in https://gitlab.kitware.com/cmake/cmake/-/issues/22845
-  # and the other CMake issues it links to.
-  #
-  # We create a nvbench-specific target that configures the nvml interface as
-  # described here:
-  # https://gitlab.kitware.com/cmake/cmake/-/issues/22845#note_1077538
-  #
-  # Use find_file instead of find_library, which would search for a .lib file.
-  # This is also nice because find_file searches recursively (find_library
-  # does not) and some versions of CTK nest nvml.dll several directories deep
-  # under C:\Windows\System32.
-  find_file(NVBench_NVML_DLL nvml.dll REQUIRED
-    DOC "The full path to nvml.dll. Usually somewhere under C:/Windows/System32."
-    PATHS "C:/Windows/System32"
-  )
-  mark_as_advanced(NVBench_NVML_DLL)
-  add_library(nvbench::nvml SHARED IMPORTED)
-  target_link_libraries(nvbench::nvml INTERFACE CUDA::toolkit)
-  set_target_properties(nvbench::nvml PROPERTIES
-    IMPORTED_LOCATION "${NVBench_NVML_DLL}"
-    IMPORTED_IMPLIB "${CUDA_nvml_LIBRARY}"
-  )
-else()
-  # Linux is much easier...
-  add_library(nvbench::nvml ALIAS CUDA::nvml)
-endif()
+# Since this file is installed, we need to make sure that the CUDAToolkit has
+# been found by consumers:
+if (NOT TARGET CUDA::toolkit)
+  find_package(CUDAToolkit REQUIRED)
+endif()
+
+if (WIN32)
+  # The CUDA:: targets currently don't provide dll locations through the
+  # `IMPORTED_LOCATION` property, nor are they marked as `SHARED` libraries
+  # (they're currently `UNKNOWN`). This prevents the `nvbench_setup_dep_dlls`
+  # CMake function from copying the dlls to the build / install directories.
+  # This is discussed in https://gitlab.kitware.com/cmake/cmake/-/issues/22845
+  # and the other CMake issues it links to.
+  #
+  # We create a nvbench-specific target that configures the nvml interface as
+  # described here:
+  # https://gitlab.kitware.com/cmake/cmake/-/issues/22845#note_1077538
+  #
+  # Use find_file instead of find_library, which would search for a .lib file.
+  # This is also nice because find_file searches recursively (find_library
+  # does not) and some versions of CTK nest nvml.dll several directories deep
+  # under C:\Windows\System32.
+  find_file(NVBench_NVML_DLL nvml.dll
+    DOC "The full path to nvml.dll. Usually somewhere under C:/Windows/System32."
+    PATHS "C:/Windows/System32"
+  )
+  mark_as_advanced(NVBench_NVML_DLL)
+endif()
+
+if (NVBench_NVML_DLL)
+  add_library(nvbench::nvml SHARED IMPORTED)
+  target_link_libraries(nvbench::nvml INTERFACE CUDA::toolkit)
+  set_target_properties(nvbench::nvml PROPERTIES
+    IMPORTED_LOCATION "${NVBench_NVML_DLL}"
+    IMPORTED_IMPLIB "${CUDA_nvml_LIBRARY}"
+  )
+elseif(TARGET CUDA::nvml)
+  add_library(nvbench::nvml ALIAS CUDA::nvml)
+else()
+  message(FATAL_ERROR "Could not find nvml.dll or CUDA::nvml target. "
+          "Set -DNVBench_ENABLE_NVML=OFF to disable NVML support "
+          "or set -DNVBench_NVML_DLL to the full path to nvml.dll on Windows.")
+endif()