--- /dev/null	2018-12-03 11:58:50.256341286 +0100
+++ new/src/hotspot/share/gc/shenandoah/shenandoahHeapRegionSet.cpp	2018-12-03 17:47:38.676327117 +0100
@@ -0,0 +1,141 @@
+/*
+ * Copyright (c) 2013, 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.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
+#include "gc/shenandoah/shenandoahHeapRegionSet.inline.hpp"
+#include "gc/shenandoah/shenandoahHeap.hpp"
+#include "gc/shenandoah/shenandoahHeap.inline.hpp"
+#include "gc/shenandoah/shenandoahHeapRegion.hpp"
+#include "gc/shenandoah/shenandoahUtils.hpp"
+#include "runtime/atomic.hpp"
+#include "utilities/copy.hpp"
+
+ShenandoahHeapRegionSetIterator::ShenandoahHeapRegionSetIterator(const ShenandoahHeapRegionSet* const set) :
+        _set(set), _heap(ShenandoahHeap::heap()), _current_index(0) {}
+
+void ShenandoahHeapRegionSetIterator::reset(const ShenandoahHeapRegionSet* const set) {
+  _set = set;
+  _current_index = 0;
+}
+
+ShenandoahHeapRegionSet::ShenandoahHeapRegionSet() :
+  _heap(ShenandoahHeap::heap()),
+  _map_size(_heap->num_regions()),
+  _region_size_bytes_shift(ShenandoahHeapRegion::region_size_bytes_shift()),
+  _set_map(NEW_C_HEAP_ARRAY(jbyte, _map_size, mtGC)),
+  _biased_set_map(_set_map - ((uintx)_heap->base() >> _region_size_bytes_shift)),
+  _region_count(0)
+{
+  // Use 1-byte data type
+  STATIC_ASSERT(sizeof(jbyte) == 1);
+
+  // Initialize cset map
+  Copy::zero_to_bytes(_set_map, _map_size);
+}
+
+ShenandoahHeapRegionSet::~ShenandoahHeapRegionSet() {
+  FREE_C_HEAP_ARRAY(jbyte, _set_map);
+}
+
+void ShenandoahHeapRegionSet::add_region(ShenandoahHeapRegion* r) {
+  assert(!is_in(r), "Already in collection set");
+  _set_map[r->region_number()] = 1;
+  _region_count++;
+}
+
+bool ShenandoahHeapRegionSet::add_region_check_for_duplicates(ShenandoahHeapRegion* r) {
+  if (!is_in(r)) {
+    add_region(r);
+    return true;
+  } else {
+    return false;
+  }
+}
+
+void ShenandoahHeapRegionSet::remove_region(ShenandoahHeapRegion* r) {
+  assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint");
+  assert(Thread::current()->is_VM_thread(), "Must be VMThread");
+  assert(is_in(r), "Not in region set");
+  _set_map[r->region_number()] = 0;
+  _region_count --;
+}
+
+void ShenandoahHeapRegionSet::clear() {
+  assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint");
+  Copy::zero_to_bytes(_set_map, _map_size);
+
+  _region_count = 0;
+}
+
+ShenandoahHeapRegion* ShenandoahHeapRegionSetIterator::claim_next() {
+  size_t num_regions = _heap->num_regions();
+  if (_current_index >= (jint)num_regions) {
+    return NULL;
+  }
+
+  jint saved_current = _current_index;
+  size_t index = (size_t)saved_current;
+
+  while(index < num_regions) {
+    if (_set->is_in(index)) {
+      jint cur = Atomic::cmpxchg((jint)(index + 1), &_current_index, saved_current);
+      assert(cur >= (jint)saved_current, "Must move forward");
+      if (cur == saved_current) {
+        assert(_set->is_in(index), "Invariant");
+        return _heap->get_region(index);
+      } else {
+        index = (size_t)cur;
+        saved_current = cur;
+      }
+    } else {
+      index ++;
+    }
+  }
+  return NULL;
+}
+
+ShenandoahHeapRegion* ShenandoahHeapRegionSetIterator::next() {
+  size_t num_regions = _heap->num_regions();
+  for (size_t index = (size_t)_current_index; index < num_regions; index ++) {
+    if (_set->is_in(index)) {
+      _current_index = (jint)(index + 1);
+      return _heap->get_region(index);
+    }
+  }
+
+  return NULL;
+}
+
+void ShenandoahHeapRegionSet::print_on(outputStream* out) const {
+  out->print_cr("Region Set : " SIZE_FORMAT "", count());
+
+  debug_only(size_t regions = 0;)
+  for (size_t index = 0; index < _heap->num_regions(); index ++) {
+    if (is_in(index)) {
+      _heap->get_region(index)->print_on(out);
+      debug_only(regions ++;)
+    }
+  }
+  assert(regions == count(), "Must match");
+}