8028207: assert(_outcnt==1) failed: not unique in compile.cpp

Reviewed-by: iveresov, kvn

src/share/vm/opto/mathexactnode.hpp

@@ -49,7 +49,7 @@ public:
   virtual Node* Identity(PhaseTransform* phase) { return this; }
   virtual Node* Ideal(PhaseGVN* phase, bool can_reshape) { return NULL; }
   virtual const Type* Value(PhaseTransform* phase) const { return bottom_type(); }
-  virtual uint hash() const { return Node::hash(); }
+  virtual uint hash() const { return NO_HASH; }
   virtual bool is_CFG() const { return false; }
   virtual uint ideal_reg() const { return NotAMachineReg; }
 

test/compiler/intrinsics/mathexact/GVNTest.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 8028207
+ * @summary Verify that GVN doesn't mess up the two addExacts
+ * @compile GVNTest.java
+ * @run main GVNTest
+ *
+ */
+
+public class GVNTest {
+  public static int result = 0;
+  public static int value = 93;
+  public static void main(String[] args) {
+    for (int i = 0; i < 50000; ++i) {
+      result = runTest(value + i);
+      result = runTest(value + i);
+      result = runTest(value + i);
+      result = runTest(value + i);
+      result = runTest(value + i);
+    }
+  }
+
+  public static int runTest(int value) {
+    int v = value + value;
+    int sum = 0;
+    if (v < 4032) {
+      for (int i = 0; i < 1023; ++i) {
+        sum += Math.addExact(value, value);
+      }
+    } else {
+      for (int i = 0; i < 321; ++i) {
+        sum += Math.addExact(value, value);
+      }
+    }
+    return sum + v;
+  }
+}