--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/z/zLiveMap.cpp	Tue Jun 12 17:40:28 2018 +0200
@@ -0,0 +1,123 @@
+/*
+ * 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.
+ */
+
+#include "precompiled.hpp"
+#include "gc/z/zHeap.inline.hpp"
+#include "gc/z/zLiveMap.inline.hpp"
+#include "gc/z/zStat.hpp"
+#include "gc/z/zThread.hpp"
+#include "logging/log.hpp"
+#include "runtime/atomic.hpp"
+#include "runtime/orderAccess.hpp"
+#include "utilities/debug.hpp"
+
+static const ZStatCounter ZCounterMarkSeqNumResetContention("Contention", "Mark SeqNum Reset Contention", ZStatUnitOpsPerSecond);
+static const ZStatCounter ZCounterMarkSegmentResetContention("Contention", "Mark Segment Reset Contention", ZStatUnitOpsPerSecond);
+
+ZLiveMap::ZLiveMap(uint32_t size) :
+    _seqnum(0),
+    _live_objects(0),
+    _live_bytes(0),
+    _segment_live_bits(0),
+    _segment_claim_bits(0),
+    // We need at least one bit per segment.
+    _bitmap(MAX2<size_t>(size, nsegments) * 2),
+    _shift(exact_log2(segment_size())) {}
+
+void ZLiveMap::reset(size_t index) {
+  const uint32_t seqnum_initializing = (uint32_t)-1;
+  bool contention = false;
+
+  // Multiple threads can enter here, make sure only one of them
+  // resets the marking information while the others busy wait.
+  for (uint32_t seqnum = _seqnum; seqnum != ZGlobalSeqNum; seqnum = _seqnum) {
+    if ((seqnum != seqnum_initializing) &&
+        (Atomic::cmpxchg(seqnum_initializing, &_seqnum, seqnum) == seqnum)) {
+      // Reset marking information
+      _live_bytes = 0;
+      _live_objects = 0;
+
+      // Clear segment claimed/live bits
+      segment_live_bits().clear();
+      segment_claim_bits().clear();
+
+      // Make sure the newly reset marking information is
+      // globally visible before updating the page seqnum.
+      OrderAccess::storestore();
+
+      // Update seqnum
+      assert(_seqnum == seqnum_initializing, "Invalid");
+      _seqnum = ZGlobalSeqNum;
+      break;
+    }
+
+    // Mark reset contention
+    if (!contention) {
+      // Count contention once, not every loop
+      ZStatInc(ZCounterMarkSeqNumResetContention);
+      contention = true;
+
+      log_trace(gc)("Mark seqnum reset contention, thread: " PTR_FORMAT " (%s), map: " PTR_FORMAT ", bit: " SIZE_FORMAT,
+                    ZThread::id(), ZThread::name(), p2i(this), index);
+    }
+  }
+}
+
+void ZLiveMap::reset_segment(BitMap::idx_t segment) {
+  bool contention = false;
+
+  if (!claim_segment(segment)) {
+    // Already claimed, wait for live bit to be set
+    while (!is_segment_live(segment)) {
+      // Busy wait. The loadload barrier is needed to make
+      // sure we re-read the live bit every time we loop.
+      OrderAccess::loadload();
+
+      // Mark reset contention
+      if (!contention) {
+        // Count contention once, not every loop
+        ZStatInc(ZCounterMarkSegmentResetContention);
+        contention = true;
+
+        log_trace(gc)("Mark segment reset contention, thread: " PTR_FORMAT " (%s), map: " PTR_FORMAT ", segment: " SIZE_FORMAT,
+                      ZThread::id(), ZThread::name(), p2i(this), segment);
+      }
+    }
+
+    // Segment is live
+    return;
+  }
+
+  // Segment claimed, clear it
+  const BitMap::idx_t start_index = segment_start(segment);
+  const BitMap::idx_t end_index   = segment_end(segment);
+  if (segment_size() / BitsPerWord >= 32) {
+    _bitmap.clear_large_range(start_index, end_index);
+  } else {
+    _bitmap.clear_range(start_index, end_index);
+  }
+
+  // Set live bit
+  const bool success = set_segment_live_atomic(segment);
+  assert(success, "Should never fail");
+}