diff -r 6b05689b7445 -r a42fefc69922 hotspot/src/share/vm/opto/stringopts.cpp
--- 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;