--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/hotspot/jtreg/compiler/c2/Test6843752.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,122 @@
+/*
+ * Copyright (c) 2009, 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.
+ */
+
+/*
+ * @test
+ * @bug 6843752
+ * @summary missing code for an anti-dependent Phi in GCM
+ *
+ * @run main/othervm -Xbatch compiler.c2.Test6843752
+ */
+
+package compiler.c2;
+
+public class Test6843752 {
+
+    Item list;
+
+    static class Item {
+        public Item    next;
+        public Item    prev;
+        public boolean remove;
+
+        Item(boolean r) { remove = r; }
+    }
+
+    private void linkIn(Item item) {
+        Item head = list;
+        if (head == null) {
+            item.next = item;
+            item.prev = item;
+            list = item;
+        } else {
+            item.next = head;
+            item.prev = head.prev;
+            head.prev.next = item;
+            head.prev = item;
+        }
+    }
+
+    private void linkOut(Item item) {
+        Item head = list;
+        if (item.next == item) {
+            list = null;
+        } else {
+            item.prev.next = item.next;
+            item.next.prev = item.prev;
+            if (head == item) {
+                list = item.next;
+            }
+        }
+        item.next = null;
+        item.prev = null; // this is the null pointer we are seeing
+    }
+
+    private void removeItems(int numItems) {
+        Item item = list;
+        if (item == null) {
+            return;
+        }
+        Item last = item.prev;
+        boolean done = false;
+        while (!done && numItems > 1) {
+            // the original code "done = (item == last);" triggered an infinite loop
+            // and was changed slightly in order to produce an exception instead.
+            done = (item.next == last.next);
+            item = item.next;
+            if (item.prev.remove) {
+                linkOut(item.prev);
+            }
+        }
+    }
+
+    public void perform(int numItems) {
+        for (int i = 0; i < numItems; i++) {
+            linkIn(new Item(i == 0));
+        }
+        removeItems(numItems);
+        list = null;
+    }
+
+    static public void main(String[] args) {
+        int caseCnt = 0;
+        Test6843752 bj = new Test6843752();
+        try {
+            for (; caseCnt < 500000;) {
+                int numItems = (++caseCnt % 2);
+                if ((caseCnt % 64) == 0) {
+                    numItems = 5;
+                }
+                bj.perform(numItems);
+                if ((caseCnt % 100000) == 0) {
+                    System.out.println("successfully performed " + caseCnt + " cases");
+                }
+            }
+        } catch (Exception e) {
+            System.out.println("ERROR: crashed during case " + caseCnt);
+            e.printStackTrace(System.out);
+            System.exit(97);
+        }
+    }
+}
+