Sycl implementation for objective functions (#9846)

---------

Co-authored-by: Dmitry Razdoburdin <>

tests/cpp/plugin/test_sycl_multiclass_obj.cc

@@ -0,0 +1,28 @@
+/*!
+ * Copyright 2018-2023 XGBoost contributors
+ */
+#include <gtest/gtest.h>
+#include <xgboost/context.h>
+
+#include "../objective/test_multiclass_obj.h"
+
+namespace xgboost {
+
+TEST(SyclObjective, SoftmaxMultiClassObjGPair) {
+  Context ctx;
+  ctx.UpdateAllowUnknown(Args{{"device", "sycl"}});
+  TestSoftmaxMultiClassObjGPair(&ctx);
+}
+
+TEST(SyclObjective, SoftmaxMultiClassBasic) {
+  Context ctx;
+  ctx.UpdateAllowUnknown(Args{{"device", "sycl"}});
+  TestSoftmaxMultiClassObjGPair(&ctx);
+}
+
+TEST(SyclObjective, SoftprobMultiClassBasic) {
+  Context ctx;
+  ctx.UpdateAllowUnknown(Args{{"device", "sycl"}});
+  TestSoftprobMultiClassBasic(&ctx);
+}
+}  // namespace xgboost