--- /dev/null	2019-02-14 11:31:37.500399000 +0100
+++ new/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/utilities/BitMapSegmented.java	2019-02-15 20:10:45.787531780 +0100
@@ -0,0 +1,99 @@
+/*
+ * Copyright (c) 2019, 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.
+ *
+ */
+
+package sun.jvm.hotspot.utilities;
+
+/** A BitMap implementing the BitMapInterface. */
+public class BitMapSegmented implements BitMapInterface {
+  private static final int SegmentSizeBits = 30;
+  private static final int SegmentSize = 1 << (SegmentSizeBits - 1);
+
+  public BitMapSegmented(long sizeInBits) {
+    this.size = sizeInBits;
+
+    if (sizeInBits == 0) {
+      segmentBitMaps = new BitMap[0];
+      return;
+    }
+
+    int lastSegmentSize = (int)(sizeInBits % SegmentSize);
+
+    int segments = segmentIndex(sizeInBits - 1) + 1;
+    int completeSegments = segments - ((lastSegmentSize != 0) ? 1 : 0);
+
+    segmentBitMaps = new BitMap[segments];
+
+    for (int i = 0; i < completeSegments; i++) {
+      segmentBitMaps[i] = new BitMap(SegmentSize);
+    }
+
+    if (lastSegmentSize != 0) {
+      segmentBitMaps[completeSegments] = new BitMap(lastSegmentSize);
+    }
+  }
+
+  public long size() {
+    return size;
+  }
+
+  // Accessors
+  public boolean at(long offset) {
+    assert offset < size;
+
+    int segmentIndex = segmentIndex(offset);
+    int segmentOffset = segmentOffset(offset);
+    return segmentBitMaps[segmentIndex].at(segmentOffset);
+  }
+
+  public void atPut(long offset, boolean value) {
+    assert offset < size;
+
+    int segmentIndex = segmentIndex(offset);
+    int segmentOffset = segmentOffset(offset);
+    segmentBitMaps[segmentIndex].atPut(segmentOffset, value);
+  }
+
+  public void clear() {
+    for (BitMap map : segmentBitMaps) {
+      map.clear();
+    }
+  }
+
+  //----------------------------------------------------------------------
+  // Internals only below this point
+  //
+  private final long     size; // in bits
+  private final BitMap[] segmentBitMaps;
+
+  private int segmentIndex(long offset) {
+    long longIndex = offset / SegmentSize;
+
+    assert longIndex < Integer.MAX_VALUE;
+    return (int)longIndex;
+  }
+
+  private int segmentOffset(long offset) {
+    return (int)(offset % SegmentSize);
+  }
+}