--- a/hotspot/src/share/vm/opto/stringopts.cpp	Fri Jan 16 05:02:11 2015 -0500
+++ b/hotspot/src/share/vm/opto/stringopts.cpp	Fri Jan 16 13:58:22 2015 +0100
@@ -1507,10 +1507,12 @@
       }
       case StringConcat::StringMode: {
         const Type* type = kit.gvn().type(arg);
+        Node* count = NULL;
         if (type == TypePtr::NULL_PTR) {
           // replace the argument with the null checked version
           arg = null_string;
           sc->set_argument(argi, arg);
+          count = kit.load_String_length(kit.control(), arg);
         } else if (!type->higher_equal(TypeInstPtr::NOTNULL)) {
           // s = s != null ? s : "null";
           // length = length + (s.count - s.offset);
@@ -1533,10 +1535,13 @@
           // replace the argument with the null checked version
           arg = phi;
           sc->set_argument(argi, arg);
+          count = kit.load_String_length(kit.control(), arg);
+        } else {
+          // A corresponding nullcheck will be connected during IGVN MemNode::Ideal_common_DU_postCCP
+          // kit.control might be a different test, that can be hoisted above the actual nullcheck
+          // in case, that the control input is not null, Ideal_common_DU_postCCP will not look for a nullcheck.
+          count = kit.load_String_length(NULL, arg);
         }
-
-        Node* count = kit.load_String_length(kit.control(), arg);
-
         length = __ AddI(length, count);
         string_sizes->init_req(argi, NULL);
         break;

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/test/compiler/stringopts/TestOptimizeStringConcat.java	Fri Jan 16 13:58:22 2015 +0100
@@ -0,0 +1,89 @@
+/*
+ * Copyright 2015 SAP AG.  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 8068909
+ * @key regression
+ * @summary test that string optimizations produce code, that doesn't lead to a crash.
+ * @run main/othervm -XX:-BackgroundCompilation -XX:-UseOnStackReplacement TestOptimizeStringConcat
+ * @author axel.siebenborn@sap.com
+ */
+public class TestOptimizeStringConcat {
+
+    static boolean checkArgumentSyntax(String value, String allowedchars, String notallowedchars, String logmsg) {
+        String rc = null;
+
+        int maxchar = 99999;
+        int minchar = 1;
+        if ((allowedchars != null && notallowedchars != null) || minchar > maxchar) {
+            rc = "internal error";
+        } else {
+            if (value == null) {
+                rc = "the value null is not allowed, it is missing";
+            } else if (value != null && minchar > 0 && value.trim().equals("")) {
+                rc = "the value must not be empty";
+            } else if (value != null) {
+                if (value.length() < minchar || value.length() > maxchar) {
+                    if (rc == null) {
+                        rc = "the value length must be between +minchar+ and +maxchar";
+                    }
+                }
+                char[] _value = value.toCharArray();
+                boolean dotfound = false;
+                int i = 1;
+                if (_value[i] == '.' && !dotfound) {
+                    dotfound = true;
+                } else if (allowedchars != null && allowedchars.indexOf(_value[i]) == -1) {
+                    if (rc == null) {
+                        rc = "the value contains an illegal character: '" + _value[i] + "', only following characters are allowed: '+allowedchars+'";
+                    } else {
+                        rc += " / the value contains an illegal character: '" + _value[i] + "', only following characters are allowed: '+allowedchars+'";
+                    }
+                } else if (notallowedchars != null && notallowedchars.indexOf(_value[i]) != -1) {
+                    if (rc == null) {
+                        rc = "the value contains an illegal character: '" + _value[i] + "', following characters are not allowed '+notallowedchars+'";
+                    } else {
+                        rc += " / the value contains an illegal character: '" + _value[i] + "', following characters are not allowed '+notallowedchars+'";
+                    }
+                }
+            }
+        }
+
+        if (rc != null) {
+            System.out.println(logmsg + " ==> " + rc);
+            return false;
+        }
+        return true;
+    }
+
+    public static void main(String[] args) {
+        boolean failed = false;
+        for (int i = 0; i < 10000; i++) {
+            failed |= !checkArgumentSyntax("theName", null, "\"<&", "Error consistencyCheck: name in component definition");
+            failed |= !checkArgumentSyntax(null, null, "\"<&", "Error consistencyCheck: name in component definition");
+            failed |= !checkArgumentSyntax("42", "0123456789.", null, "Error consistencyCheck: counter in component definition");
+        }
+        System.out.println(failed);
+    }
+}