[CI] Make oneapi_plugin a CMake target

CMakeLists.txt

@@ -114,8 +114,6 @@ if (USE_OPENMP)
   find_package(OpenMP REQUIRED)
 endif (USE_OPENMP)
 
-add_library(objxgboost OBJECT)
-
 # core xgboost
 add_subdirectory(${xgboost_SOURCE_DIR}/src)
 
@@ -174,12 +172,6 @@ endif (R_LIB)
 # Plugin
 add_subdirectory(${xgboost_SOURCE_DIR}/plugin)
 
-#-- DPC++ support
-if (PLUGIN_UPDATER_ONEAPI)
-  set_source_files_properties(${PLUGINS_SOURCES_ONEAPI} PROPERTIES COMPILE_FLAGS -fsycl)
-endif (PLUGIN_UPDATER_ONEAPI)
-#-- End of DPC++ support
-
 #-- library
 if (BUILD_STATIC_LIB)
   add_library(xgboost STATIC)

plugin/CMakeLists.txt

@@ -8,14 +8,27 @@ if (PLUGIN_DENSE_PARSER)
 endif (PLUGIN_DENSE_PARSER)
 
 if (PLUGIN_UPDATER_ONEAPI)
-
-  set(PLUGINS_SOURCES_ONEAPI 
+  add_library(oneapi_plugin OBJECT
     ${xgboost_SOURCE_DIR}/plugin/updater_oneapi/regression_obj_oneapi.cc 
     ${xgboost_SOURCE_DIR}/plugin/updater_oneapi/predictor_oneapi.cc)
-
-  set(PLUGINS_SOURCES_ONEAPI ${PLUGINS_SOURCES_ONEAPI} PARENT_SCOPE)
-
-  target_sources(objxgboost PRIVATE ${PLUGINS_SOURCES_ONEAPI})
-  target_compile_definitions(objxgboost PRIVATE -DXGBOOST_USE_ONEAPI=1)
-  target_link_libraries(objxgboost PUBLIC -fsycl)
+  target_include_directories(oneapi_plugin
+    PRIVATE
+    ${xgboost_SOURCE_DIR}/include
+    ${xgboost_SOURCE_DIR}/dmlc-core/include
+    ${xgboost_SOURCE_DIR}/rabit/include)
+  target_compile_definitions(oneapi_plugin PUBLIC -DXGBOOST_USE_ONEAPI=1)
+  target_link_libraries(oneapi_plugin PUBLIC -fsycl)
+  set_target_properties(oneapi_plugin PROPERTIES
+    COMPILE_FLAGS -fsycl
+    CXX_STANDARD 14
+    CXX_STANDARD_REQUIRED ON
+    POSITION_INDEPENDENT_CODE ON)
+  if (USE_OPENMP)
+    find_package(OpenMP REQUIRED)
+    target_link_libraries(oneapi_plugin PUBLIC OpenMP::OpenMP_CXX)
+  endif (USE_OPENMP)
+  # Get compilation and link flags of oneapi_plugin and propagate to objxgboost
+  target_link_libraries(objxgboost PUBLIC oneapi_plugin)
+  # Add all objects of oneapi_plugin to objxgboost
+  target_sources(objxgboost INTERFACE $<TARGET_OBJECTS:oneapi_plugin>)
 endif (PLUGIN_UPDATER_ONEAPI)

src/CMakeLists.txt

@@ -3,6 +3,7 @@ list(REMOVE_ITEM CPU_SOURCES ${xgboost_SOURCE_DIR}/src/cli_main.cc)
 
 #-- Object library
 # Object library is necessary for jvm-package, which creates its own shared library.
+add_library(objxgboost OBJECT)
 target_sources(objxgboost PRIVATE ${CPU_SOURCES})
 if (USE_CUDA)
   file(GLOB_RECURSE CUDA_SOURCES *.cu *.cuh)