--- a/hotspot/src/share/vm/opto/superword.cpp	Thu Oct 29 16:57:55 2009 -0700
+++ b/hotspot/src/share/vm/opto/superword.cpp	Fri Oct 30 10:12:52 2009 -0700
@@ -1921,6 +1921,11 @@
   }
   // Match AddP(base, AddP(ptr, k*iv [+ invariant]), constant)
   Node* base = adr->in(AddPNode::Base);
+  //unsafe reference could not be aligned appropriately without runtime checking
+  if (base == NULL || base->bottom_type() == Type::TOP) {
+    assert(!valid(), "unsafe access");
+    return;
+  }
   for (int i = 0; i < 3; i++) {
     if (!scaled_iv_plus_offset(adr->in(AddPNode::Offset))) {
       assert(!valid(), "too complex");

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/test/compiler/6852078/Test6852078.java	Fri Oct 30 10:12:52 2009 -0700
@@ -0,0 +1,57 @@
+/*
+ * 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 6852078
+ * @summary Disable SuperWord optimization for unsafe read/write
+ *
+ * @run main/othervm Test6852078
+ */
+
+import java.util.*;
+import java.nio.ByteBuffer;
+import com.sun.corba.se.impl.encoding.ByteBufferWithInfo;
+import com.sun.jndi.toolkit.corba.CorbaUtils;
+
+public class Test6852078 {
+
+    public Test6852078(String [] args) {
+
+        int capacity = 128;
+        ByteBuffer bb = ByteBuffer.allocateDirect(capacity);
+        ByteBufferWithInfo bbwi = new ByteBufferWithInfo( CorbaUtils.getOrb(null, -1, new Hashtable()), bb);
+        byte[] tmpBuf;
+        tmpBuf = new byte[bbwi.buflen];
+
+        for (int i = 0; i < capacity; i++)
+            tmpBuf[i] = bbwi.byteBuffer.get(i);
+    }
+
+    public static void main(String [] args) {
+        for (int i=0; i<2000; i++) {
+            Test6852078 t = new Test6852078(args);
+        }
+    }
+}