6901572: JVM 1.6.16 crash on loops: assert(has_node(i),"")

Summary: Skip the secondary induction variable handling if it is dead
Reviewed-by: never, kvn

src/share/vm/opto/loopnode.cpp

@@ -1279,7 +1279,8 @@ void IdealLoopTree::counted_loop( PhaseIdealLoop *phase ) {
     // Visit all children, looking for Phis
     for (DUIterator i = cl->outs(); cl->has_out(i); i++) {
       Node *out = cl->out(i);
-      if (!out->is_Phi() || out == phi)  continue; // Looking for other phis
+      // Look for other phis (secondary IVs). Skip dead ones
+      if (!out->is_Phi() || out == phi || !phase->has_node(out)) continue;
       PhiNode* phi2 = out->as_Phi();
       Node *incr2 = phi2->in( LoopNode::LoopBackControl );
       // Look for induction variables of the form:  X += constant

test/compiler/6901572/Test.java

+/*
+ * Copyright 2009 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/**
+ * @test
+ * @bug 6901572
+ * @summary JVM 1.6.16 crash on loops: assert(has_node(i),"")
+ *
+ * @run main/othervm Test
+ */
+
+
+public class Test {
+
+    public static void main(String[] args) {
+        for (int i = 0; i < 2; i++)
+            NestedLoop();
+    }
+
+    public static long NestedLoop() {
+        final int n = 50;
+        long startTime = System.currentTimeMillis();
+        int x = 0;
+        for(int a = 0; a < n; a++)
+            for(int b = 0; b < n; b++)
+                for(int c = 0; c < n; c++)
+                    for(int d = 0; d < n; d++)
+                        for(int e = 0; e < n; e++)
+                            for(int f = 0; f < n; f++)
+                                x++;
+        long stopTime = System.currentTimeMillis();
+
+        return stopTime - startTime;
+    }
+}