cmake : add FindNCCL.cmake (ggml/0)

ggml/cmake/FindNCCL.cmake

@@ -0,0 +1,36 @@
+# cmake/FindNCCL.cmake
+
+# NVIDIA does not distribute CMake files with NCCl, therefore use this file to find it instead.
+
+find_path(NCCL_INCLUDE_DIR
+    NAMES nccl.h
+    HINTS ${NCCL_ROOT} $ENV{NCCL_ROOT} $ENV{CUDA_HOME} /usr/local/cuda
+    PATH_SUFFIXES include
+)
+
+find_library(NCCL_LIBRARY
+    NAMES nccl
+    HINTS ${NCCL_ROOT} $ENV{NCCL_ROOT} $ENV{CUDA_HOME} /usr/local/cuda
+    PATH_SUFFIXES lib lib64
+)
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(NCCL
+    DEFAULT_MSG
+    NCCL_LIBRARY NCCL_INCLUDE_DIR
+)
+
+if(NCCL_FOUND)
+    set(NCCL_LIBRARIES ${NCCL_LIBRARY})
+    set(NCCL_INCLUDE_DIRS ${NCCL_INCLUDE_DIR})
+
+    if(NOT TARGET NCCL::NCCL)
+        add_library(NCCL::NCCL UNKNOWN IMPORTED)
+        set_target_properties(NCCL::NCCL PROPERTIES
+            IMPORTED_LOCATION "${NCCL_LIBRARY}"
+            INTERFACE_INCLUDE_DIRECTORIES "${NCCL_INCLUDE_DIR}"
+        )
+    endif()
+endif()
+
+mark_as_advanced(NCCL_INCLUDE_DIR NCCL_LIBRARY)