[openmp] - add support for openmp-config.cmake (llvm#2706)

Author: ronlieb

openmp/runtime/openmp-config.cmake.in

@@ -0,0 +1,12 @@
+@PACKAGE_INIT@
+get_filename_component(openmp_PACKAGE_PREFIX_DIR "${PACKAGE_PREFIX_DIR}" REALPATH)
+
+set( openmp_LIB_DIR "@OPENMP_INSTALL_LIBDIR@" )
+set_and_check( openmp_LIB_INSTALL_DIR "@CMAKE_INSTALL_PREFIX@/@OPENMP_INSTALL_LIBDIR@" )
+set_and_check( openmp_LIB_INSTALL_PREFIX "@CMAKE_INSTALL_PREFIX@")
+
+string(REPLACE "${openmp_PACKAGE_PREFIX_DIR}/" "" openmp_LIB_NO_PACKAGE_PREFIX_PATH_TEMP ${openmp_LIB_INSTALL_DIR})
+set(openmp_LIB_NO_PACKAGE_PREFIX_PATH ${openmp_LIB_NO_PACKAGE_PREFIX_PATH_TEMP})
+
+
+include( "${CMAKE_CURRENT_LIST_DIR}/openmpTargets.cmake" )

openmp/runtime/src/CMakeLists.txt

@@ -457,12 +457,23 @@ if(WIN32)
       \"${alias}${CMAKE_STATIC_LIBRARY_SUFFIX}\" WORKING_DIRECTORY \"${outdir}\")")
   endforeach()
 else()
-
   if(${CMAKE_SYSTEM_NAME} MATCHES "AIX")
     install(FILES ${LIBOMP_LIBRARY_DIR}/libomp.a DESTINATION "${OPENMP_INSTALL_LIBDIR}" COMPONENT runtime)
   else()
-    install(TARGETS omp ${export_to_llvmexports} ${LIBOMP_INSTALL_KIND} DESTINATION "${OPENMP_INSTALL_LIBDIR}")
+    install(TARGETS omp ${export_to_llvmexports} EXPORT openmpTargets ${LIBOMP_INSTALL_KIND}
+            DESTINATION "${OPENMP_INSTALL_LIBDIR}")
+    install(EXPORT openmpTargets FILE openmpTargets.cmake NAMESPACE OpenMP::
+            DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/openmp)
   endif()
+  # Create cmake configuration files
+  include(CMakePackageConfigHelpers)
+
+  configure_package_config_file(
+   ../openmp-config.cmake.in
+   openmp-config.cmake
+   INSTALL_DESTINATION ${OPENMP_INSTALL_LIBDIR}/cmake/openmp )
+  install(FILES ${CMAKE_CURRENT_BINARY_DIR}/openmp-config.cmake
+          DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/openmp )
 
   if(${LIBOMP_INSTALL_ALIASES})
     # Create aliases (symlinks) of the library for backwards compatibility