--- /dev/null	2018-11-30 10:10:44.238550338 +0100
+++ new/src/hotspot/share/gc/shenandoah/shenandoahNumberSeq.cpp	2018-11-30 21:09:15.419755484 +0100
@@ -0,0 +1,189 @@
+/*
+ * 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.
+ *
+ */
+
+#include "precompiled.hpp"
+
+#include "gc/shenandoah/shenandoahNumberSeq.hpp"
+#include "runtime/atomic.hpp"
+
+HdrSeq::HdrSeq() {
+  _hdr = NEW_C_HEAP_ARRAY(int*, MagBuckets, mtInternal);
+  for (int c = 0; c < MagBuckets; c++) {
+    _hdr[c] = NULL;
+  }
+}
+
+HdrSeq::~HdrSeq() {
+  for (int c = 0; c < MagBuckets; c++) {
+    int* sub = _hdr[c];
+    if (sub != NULL) {
+      FREE_C_HEAP_ARRAY(int, sub);
+    }
+  }
+  FREE_C_HEAP_ARRAY(int*, _hdr);
+}
+
+void HdrSeq::add(double val) {
+  if (val < 0) {
+    assert (false, "value (%8.2f) is not negative", val);
+    val = 0;
+  }
+
+  NumberSeq::add(val);
+
+  double v = val;
+  int mag;
+  if (v > 0) {
+    mag = 0;
+    while (v > 1) {
+      mag++;
+      v /= 10;
+    }
+    while (v < 0.1) {
+      mag--;
+      v *= 10;
+    }
+  } else {
+    mag = MagMinimum;
+  }
+
+  int bucket = -MagMinimum + mag;
+  int sub_bucket = (int) (v * ValBuckets);
+
+  // Defensively saturate for product bits:
+  if (bucket < 0) {
+    assert (false, "bucket index (%d) underflow for value (%8.2f)", bucket, val);
+    bucket = 0;
+  }
+
+  if (bucket >= MagBuckets) {
+    assert (false, "bucket index (%d) overflow for value (%8.2f)", bucket, val);
+    bucket = MagBuckets - 1;
+  }
+
+  if (sub_bucket < 0) {
+    assert (false, "sub-bucket index (%d) underflow for value (%8.2f)", sub_bucket, val);
+    sub_bucket = 0;
+  }
+
+  if (sub_bucket >= ValBuckets) {
+    assert (false, "sub-bucket index (%d) overflow for value (%8.2f)", sub_bucket, val);
+    sub_bucket = ValBuckets - 1;
+  }
+
+  int* b = _hdr[bucket];
+  if (b == NULL) {
+    b = NEW_C_HEAP_ARRAY(int, ValBuckets, mtInternal);
+    for (int c = 0; c < ValBuckets; c++) {
+      b[c] = 0;
+    }
+    _hdr[bucket] = b;
+  }
+  b[sub_bucket]++;
+}
+
+double HdrSeq::percentile(double level) const {
+  // target should be non-zero to find the first sample
+  int target = MAX2(1, (int) (level * num() / 100));
+  int cnt = 0;
+  for (int mag = 0; mag < MagBuckets; mag++) {
+    if (_hdr[mag] != NULL) {
+      for (int val = 0; val < ValBuckets; val++) {
+        cnt += _hdr[mag][val];
+        if (cnt >= target) {
+          return pow(10.0, MagMinimum + mag) * val / ValBuckets;
+        }
+      }
+    }
+  }
+  return maximum();
+}
+
+BinaryMagnitudeSeq::BinaryMagnitudeSeq() {
+  _mags = NEW_C_HEAP_ARRAY(size_t, BitsPerSize_t, mtInternal);
+  for (int c = 0; c < BitsPerSize_t; c++) {
+    _mags[c] = 0;
+  }
+  _sum = 0;
+}
+
+BinaryMagnitudeSeq::~BinaryMagnitudeSeq() {
+  FREE_C_HEAP_ARRAY(size_t, _mags);
+}
+
+void BinaryMagnitudeSeq::add(size_t val) {
+  Atomic::add(val, &_sum);
+
+  int mag = log2_intptr(val) + 1;
+
+  // Defensively saturate for product bits:
+  if (mag < 0) {
+    assert (false, "bucket index (%d) underflow for value (" SIZE_FORMAT ")", mag, val);
+    mag = 0;
+  }
+
+  if (mag >= BitsPerSize_t) {
+    assert (false, "bucket index (%d) overflow for value (" SIZE_FORMAT ")", mag, val);
+    mag = BitsPerSize_t - 1;
+  }
+
+  Atomic::add((size_t)1, &_mags[mag]);
+}
+
+size_t BinaryMagnitudeSeq::level(int level) const {
+  if (0 <= level && level < BitsPerSize_t) {
+    return _mags[level];
+  } else {
+    return 0;
+  }
+}
+
+size_t BinaryMagnitudeSeq::num() const {
+  size_t r = 0;
+  for (int c = 0; c < BitsPerSize_t; c++) {
+    r += _mags[c];
+  }
+  return r;
+}
+
+size_t BinaryMagnitudeSeq::sum() const {
+  return _sum;
+}
+
+int BinaryMagnitudeSeq::min_level() const {
+  for (int c = 0; c < BitsPerSize_t; c++) {
+    if (_mags[c] != 0) {
+      return c;
+    }
+  }
+  return BitsPerSize_t - 1;
+}
+
+int BinaryMagnitudeSeq::max_level() const {
+  for (int c = BitsPerSize_t - 1; c > 0; c--) {
+    if (_mags[c] != 0) {
+      return c;
+    }
+  }
+  return 0;
+}