--- /dev/null	2018-12-03 11:58:50.256341286 +0100
+++ new/src/hotspot/share/gc/shenandoah/shenandoahUtils.hpp	2018-12-03 17:48:57.666763095 +0100
@@ -0,0 +1,178 @@
+/*
+ * Copyright (c) 2017, 2018, Red Hat, Inc. All rights reserved.
+ *
+ * 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.
+ *
+ */
+
+#ifndef SHARE_VM_GC_SHENANDOAHUTILS_HPP
+#define SHARE_VM_GC_SHENANDOAHUTILS_HPP
+
+#include "jfr/jfrEvents.hpp"
+
+#include "gc/shared/gcCause.hpp"
+#include "gc/shared/isGCActiveMark.hpp"
+#include "gc/shared/suspendibleThreadSet.hpp"
+#include "gc/shared/vmGCOperations.hpp"
+#include "gc/shenandoah/shenandoahPhaseTimings.hpp"
+#include "gc/shenandoah/shenandoahThreadLocalData.hpp"
+#include "memory/allocation.hpp"
+#include "runtime/safepoint.hpp"
+#include "runtime/vmThread.hpp"
+#include "runtime/vm_operations.hpp"
+#include "services/memoryService.hpp"
+
+class GCTimer;
+class GCTracer;
+
+class ShenandoahGCSession : public StackObj {
+private:
+  ShenandoahHeap* const _heap;
+  GCTimer*  const _timer;
+  GCTracer* const _tracer;
+
+  TraceMemoryManagerStats _trace_cycle;
+public:
+  ShenandoahGCSession(GCCause::Cause cause);
+  ~ShenandoahGCSession();
+};
+
+class ShenandoahGCPhase : public StackObj {
+private:
+  static const ShenandoahPhaseTimings::Phase _invalid_phase = ShenandoahPhaseTimings::_num_phases;
+  static ShenandoahPhaseTimings::Phase       _current_phase;
+
+  ShenandoahHeap* const _heap;
+  const ShenandoahPhaseTimings::Phase   _phase;
+  ShenandoahPhaseTimings::Phase         _parent_phase;
+public:
+  ShenandoahGCPhase(ShenandoahPhaseTimings::Phase phase);
+  ~ShenandoahGCPhase();
+
+  static ShenandoahPhaseTimings::Phase current_phase() { return _current_phase; }
+
+  static bool is_valid_phase(ShenandoahPhaseTimings::Phase phase);
+  static bool is_current_phase_valid() { return is_valid_phase(current_phase()); }
+  static bool is_root_work_phase();
+};
+
+// Aggregates all the things that should happen before/after the pause.
+class ShenandoahGCPauseMark : public StackObj {
+private:
+  ShenandoahHeap* const _heap;
+  const GCIdMark                _gc_id_mark;
+  const SvcGCMarker             _svc_gc_mark;
+  const IsGCActiveMark          _is_gc_active_mark;
+  TraceMemoryManagerStats       _trace_pause;
+
+public:
+  ShenandoahGCPauseMark(uint gc_id, SvcGCMarker::reason_type type);
+  ~ShenandoahGCPauseMark();
+};
+
+class ShenandoahAllocTrace : public StackObj {
+private:
+  double _start;
+  size_t _size;
+  ShenandoahAllocRequest::Type _alloc_type;
+public:
+  ShenandoahAllocTrace(size_t words_size, ShenandoahAllocRequest::Type alloc_type);
+  ~ShenandoahAllocTrace();
+};
+
+class ShenandoahSafepoint : public AllStatic {
+public:
+  // check if Shenandoah GC safepoint is in progress
+  static inline bool is_at_shenandoah_safepoint() {
+    if (!SafepointSynchronize::is_at_safepoint()) return false;
+
+    VM_Operation* vm_op = VMThread::vm_operation();
+    if (vm_op == NULL) return false;
+
+    VM_Operation::VMOp_Type type = vm_op->type();
+    return type == VM_Operation::VMOp_ShenandoahInitMark ||
+           type == VM_Operation::VMOp_ShenandoahFinalMarkStartEvac ||
+           type == VM_Operation::VMOp_ShenandoahFinalEvac ||
+           type == VM_Operation::VMOp_ShenandoahInitTraversalGC ||
+           type == VM_Operation::VMOp_ShenandoahFinalTraversalGC ||
+           type == VM_Operation::VMOp_ShenandoahInitUpdateRefs ||
+           type == VM_Operation::VMOp_ShenandoahFinalUpdateRefs ||
+           type == VM_Operation::VMOp_ShenandoahFullGC ||
+           type == VM_Operation::VMOp_ShenandoahDegeneratedGC;
+  }
+};
+
+class ShenandoahWorkerSession : public StackObj {
+protected:
+  uint _worker_id;
+
+  ShenandoahWorkerSession(uint worker_id);
+  ~ShenandoahWorkerSession();
+public:
+  static inline uint worker_id() {
+    Thread* thr = Thread::current();
+    uint id = ShenandoahThreadLocalData::worker_id(thr);
+    assert(id != ShenandoahThreadLocalData::INVALID_WORKER_ID, "Worker session has not been created");
+    return id;
+  }
+};
+
+class ShenandoahConcurrentWorkerSession : public ShenandoahWorkerSession {
+private:
+  EventGCPhaseConcurrent _event;
+
+public:
+  ShenandoahConcurrentWorkerSession(uint worker_id) : ShenandoahWorkerSession(worker_id) { }
+  ~ShenandoahConcurrentWorkerSession();
+};
+
+class ShenandoahParallelWorkerSession : public ShenandoahWorkerSession {
+private:
+  EventGCPhaseParallel _event;
+
+public:
+  ShenandoahParallelWorkerSession(uint worker_id) : ShenandoahWorkerSession(worker_id) { }
+  ~ShenandoahParallelWorkerSession();
+};
+
+class ShenandoahSuspendibleThreadSetJoiner {
+private:
+  SuspendibleThreadSetJoiner _joiner;
+public:
+  ShenandoahSuspendibleThreadSetJoiner(bool active = true) : _joiner(active) {
+    assert(!ShenandoahThreadLocalData::is_evac_allowed(Thread::current()), "STS should be joined before evac scope");
+  }
+  ~ShenandoahSuspendibleThreadSetJoiner() {
+    assert(!ShenandoahThreadLocalData::is_evac_allowed(Thread::current()), "STS should be left after evac scope");
+  }
+};
+
+class ShenandoahSuspendibleThreadSetLeaver {
+private:
+  SuspendibleThreadSetLeaver _leaver;
+public:
+  ShenandoahSuspendibleThreadSetLeaver(bool active = true) : _leaver(active) {
+    assert(!ShenandoahThreadLocalData::is_evac_allowed(Thread::current()), "STS should be left after evac scope");
+  }
+  ~ShenandoahSuspendibleThreadSetLeaver() {
+    assert(!ShenandoahThreadLocalData::is_evac_allowed(Thread::current()), "STS should be joined before evac scope");
+  }
+};
+
+#endif // SHARE_VM_GC_SHENANDOAHUTILS_HPP