--- /dev/null	2020-04-03 11:05:12.059730817 +0200
+++ new/src/hotspot/share/gc/shenandoah/shenandoahIUMode.cpp	2020-04-03 22:13:10.435224678 +0200
@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2020, Red Hat, Inc. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "gc/shenandoah/shenandoahConcurrentRoots.hpp"
+#include "gc/shenandoah/shenandoahIUMode.hpp"
+#include "gc/shenandoah/heuristics/shenandoahAdaptiveHeuristics.hpp"
+#include "gc/shenandoah/heuristics/shenandoahAggressiveHeuristics.hpp"
+#include "gc/shenandoah/heuristics/shenandoahCompactHeuristics.hpp"
+#include "gc/shenandoah/heuristics/shenandoahStaticHeuristics.hpp"
+#include "logging/log.hpp"
+#include "logging/logTag.hpp"
+
+void ShenandoahIUMode::initialize_flags() const {
+  if (ShenandoahConcurrentRoots::can_do_concurrent_class_unloading()) {
+    FLAG_SET_DEFAULT(ShenandoahSuspendibleWorkers, true);
+    FLAG_SET_DEFAULT(VerifyBeforeExit, false);
+  }
+
+  FLAG_SET_DEFAULT(ShenandoahStoreValEnqueueBarrier, true);
+  FLAG_SET_DEFAULT(ShenandoahSATBBarrier, false);
+
+  SHENANDOAH_ERGO_ENABLE_FLAG(ExplicitGCInvokesConcurrent);
+  SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahImplicitGCInvokesConcurrent);
+
+  // Final configuration checks
+  SHENANDOAH_CHECK_FLAG_SET(ShenandoahLoadRefBarrier);
+  SHENANDOAH_CHECK_FLAG_SET(ShenandoahStoreValEnqueueBarrier);
+  SHENANDOAH_CHECK_FLAG_SET(ShenandoahCASBarrier);
+  SHENANDOAH_CHECK_FLAG_SET(ShenandoahCloneBarrier);
+}