diff -r 420ff459906f -r 9c18c9d839d3 src/hotspot/share/gc/shenandoah/shenandoahMarkingContext.hpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/shenandoah/shenandoahMarkingContext.hpp	Mon Dec 10 15:47:44 2018 +0100
@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 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_SHENANDOAH_SHENANDOAHMARKINGCONTEXT_HPP
+#define SHARE_VM_GC_SHENANDOAH_SHENANDOAHMARKINGCONTEXT_HPP
+
+#include "gc/shared/markBitMap.hpp"
+#include "memory/allocation.hpp"
+#include "memory/memRegion.hpp"
+#include "oops/oopsHierarchy.hpp"
+
+class HeapWord;
+
+/**
+ * Encapsulate a marking bitmap with the top-at-mark-start and top-bitmaps array.
+ */
+class ShenandoahMarkingContext : public CHeapObj<mtGC> {
+private:
+  MarkBitMap _mark_bit_map;
+
+  HeapWord** const _top_bitmaps;
+  HeapWord** const _top_at_mark_starts_base;
+  HeapWord** const _top_at_mark_starts;
+
+  ShenandoahSharedFlag _is_complete;
+
+public:
+  ShenandoahMarkingContext(MemRegion heap_region, MemRegion bitmap_region, size_t num_regions);
+
+  /*
+   * Marks the object. Returns true if the object has not been marked before and has
+   * been marked by this thread. Returns false if the object has already been marked,
+   * or if a competing thread succeeded in marking this object.
+   */
+  inline bool mark(oop obj);
+
+  inline bool is_marked(oop obj) const;
+
+  inline bool allocated_after_mark_start(HeapWord* addr) const;
+
+  inline MarkBitMap* mark_bit_map();
+
+  HeapWord* top_at_mark_start(ShenandoahHeapRegion* r) const;
+  void capture_top_at_mark_start(ShenandoahHeapRegion* r);
+  void reset_top_at_mark_start(ShenandoahHeapRegion* r);
+  void initialize_top_at_mark_start(ShenandoahHeapRegion* r);
+
+  void reset_top_bitmap(ShenandoahHeapRegion *r);
+  void clear_bitmap(ShenandoahHeapRegion *r);
+
+  bool is_bitmap_clear() const;
+  bool is_bitmap_clear_range(HeapWord* start, HeapWord* end) const;
+
+  bool is_complete();
+  void mark_complete();
+  void mark_incomplete();
+
+};
+
+#endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHMARKINGCONTEXT_HPP