8023472: C2 optimization breaks with G1

Summary: set control edge for previous value load in G1 pre-barrier
Reviewed-by: twisti

src/share/vm/opto/graphKit.cpp

@@ -3595,7 +3595,7 @@ void GraphKit::g1_write_barrier_pre(bool do_load,
     if (do_load) {
       // load original value
       // alias_idx correct??
-      pre_val = __ load(no_ctrl, adr, val_type, bt, alias_idx);
+      pre_val = __ load(__ ctrl(), adr, val_type, bt, alias_idx);
     }
 
     // if (pre_val != NULL)

test/compiler/gcbarriers/G1CrashTest.java

+/*
+ * Copyright (c) 2013, 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 8023472
+ * @summary C2 optimization breaks with G1
+ *
+ * @run main/othervm -Xbatch -XX:+IgnoreUnrecognizedVMOptions -XX:-TieredCompilation -Dcount=100000 G1CrashTest
+ *
+ * @author pbiswal@palantir.com
+ */
+
+public class G1CrashTest {
+    static Object[] set = new Object[11];
+
+    public static void main(String[] args) throws InterruptedException {
+        for (int j = 0; j < Integer.getInteger("count"); j++) {
+            Object key = new Object();
+            insertKey(key);
+            if (j > set.length / 2) {
+                Object[] oldKeys = set;
+                set = new Object[2 * set.length - 1];
+                for (Object o : oldKeys) {
+                    if (o != null)
+                        insertKey(o);
+                }
+            }
+        }
+    }
+
+    static void insertKey(Object key) {
+        int hash = key.hashCode() & 0x7fffffff;
+        int index = hash % set.length;
+        Object cur = set[index];
+        if (cur == null)
+            set[index] = key;
+        else
+            insertKeyRehash(key, index, hash, cur);
+    }
+
+    static void insertKeyRehash(Object key, int index, int hash, Object cur) {
+        int loopIndex = index;
+        int firstRemoved = -1;
+        do {
+            if (cur == "dead")
+                firstRemoved = 1;
+            index--;
+            if (index < 0)
+                index += set.length;
+            cur = set[index];
+            if (cur == null) {
+                if (firstRemoved != -1)
+                    set[firstRemoved] = "dead";
+                else
+                    set[index] = key;
+                return;
+            }
+        } while (index != loopIndex);
+        if (firstRemoved != -1)
+            set[firstRemoved] = null;
+    }
+}