--- /dev/null	2020-01-17 11:46:19.065201212 +0100
+++ new/src/hotspot/share/gc/shared/markBitMap.cpp	2020-01-17 17:15:15.078113674 +0100
@@ -0,0 +1,82 @@
+/*
+ * Copyright (c) 2015, 2018, Oracle and/or its affiliates. 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.
+ *
+ */
+
+// Concurrent marking bit map wrapper
+
+#include "precompiled.hpp"
+#include "gc/shared/markBitMap.inline.hpp"
+#include "utilities/bitMap.inline.hpp"
+
+MarkBitMapRO::MarkBitMapRO(int shifter) :
+  _bm(),
+  _shifter(shifter) {
+  _bmStartWord = 0;
+  _bmWordSize = 0;
+}
+
+#ifndef PRODUCT
+bool MarkBitMapRO::covers(MemRegion heap_rs) const {
+  // assert(_bm.map() == _virtual_space.low(), "map inconsistency");
+  assert(((size_t)_bm.size() * ((size_t)1 << _shifter)) == _bmWordSize,
+         "size inconsistency");
+  return _bmStartWord == (HeapWord*)(heap_rs.start()) &&
+         _bmWordSize  == heap_rs.word_size();
+}
+#endif
+
+void MarkBitMapRO::print_on_error(outputStream* st, const char* prefix) const {
+  _bm.print_on_error(st, prefix);
+}
+
+size_t MarkBitMap::compute_size(size_t heap_size) {
+  return ReservedSpace::allocation_align_size_up(heap_size / mark_distance());
+}
+
+size_t MarkBitMap::mark_distance() {
+  return MinObjAlignmentInBytes * BitsPerByte;
+}
+
+void MarkBitMap::initialize(MemRegion heap, MemRegion bitmap) {
+  _bmStartWord = heap.start();
+  _bmWordSize = heap.word_size();
+
+  _bm = BitMapView((BitMap::bm_word_t*) bitmap.start(), _bmWordSize >> _shifter);
+  _covered = heap;
+}
+
+void MarkBitMap::do_clear(MemRegion mr, bool large) {
+  MemRegion intersection = mr.intersection(_covered);
+  assert(!intersection.is_empty(),
+         "Given range from " PTR_FORMAT " to " PTR_FORMAT " is completely outside the heap",
+         p2i(mr.start()), p2i(mr.end()));
+  // convert address range into offset range
+  size_t beg = heapWordToOffset(intersection.start());
+  size_t end = heapWordToOffset(intersection.end());
+  if (large) {
+    _bm.clear_large_range(beg, end);
+  } else {
+    _bm.clear_range(beg, end);
+  }
+}
+