7012088: jump to 0 address because of lack of memory ordering in SignatureHandlerLibrary::add

Summary: Write method signature handler under lock to prevent race with growable array resizing
Reviewed-by: dsamersoff, dholmes

src/share/vm/interpreter/interpreterRuntime.cpp

@@ -1184,9 +1184,7 @@ void SignatureHandlerLibrary::add(methodHandle method) {
           handler_index = _fingerprints->length() - 1;
         }
       }
-    } else {
-      CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops());
-    }
+      // Set handler under SignatureHandlerLibrary_lock
     if (handler_index < 0) {
       // use generic signature handler
       method->set_signature_handler(Interpreter::slow_signature_handler());
@@ -1194,21 +1192,29 @@ void SignatureHandlerLibrary::add(methodHandle method) {
       // set handler
       method->set_signature_handler(_handlers->at(handler_index));
     }
+    } else {
+      CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops());
+      // use generic signature handler
+      method->set_signature_handler(Interpreter::slow_signature_handler());
+    }
   }
 #ifdef ASSERT
-  int handler_index, fingerprint_index;
+  int handler_index = -1;
+  int fingerprint_index = -2;
   {
     // '_handlers' and '_fingerprints' are 'GrowableArray's and are NOT synchronized
     // in any way if accessed from multiple threads. To avoid races with another
     // thread which may change the arrays in the above, mutex protected block, we
     // have to protect this read access here with the same mutex as well!
     MutexLocker mu(SignatureHandlerLibrary_lock);
+    if (_handlers != NULL) {
     handler_index = _handlers->find(method->signature_handler());
     fingerprint_index = _fingerprints->find(Fingerprinter(method).fingerprint());
   }
+  }
   assert(method->signature_handler() == Interpreter::slow_signature_handler() ||
          handler_index == fingerprint_index, "sanity check");
-#endif
+#endif // ASSERT
 }