--- a/src/share/vm/oops/method.cpp	Fri Dec 14 10:20:54 2012 +0100
+++ b/src/share/vm/oops/method.cpp	Fri Dec 14 14:35:13 2012 +0100
@@ -67,6 +67,7 @@
                          int localvariable_table_length,
                          int exception_table_length,
                          int checked_exceptions_length,
+                         u2  generic_signature_index,
                          ConstMethod::MethodType method_type,
                          TRAPS) {
   assert(!access_flags.is_native() || byte_code_size == 0,
@@ -77,6 +78,7 @@
                                           localvariable_table_length,
                                           exception_table_length,
                                           checked_exceptions_length,
+                                          generic_signature_index,
                                           method_type,
                                           CHECK_NULL);
 
@@ -1042,7 +1044,7 @@
   methodHandle m;
   {
     Method* m_oop = Method::allocate(loader_data, 0, accessFlags_from(flags_bits),
-            0, 0, 0, 0, ConstMethod::NORMAL, CHECK_(empty));
+             0, 0, 0, 0, 0, ConstMethod::NORMAL, CHECK_(empty));
     m = methodHandle(THREAD, m_oop);
   }
   m->set_constants(cp());
@@ -1090,6 +1092,7 @@
   assert(!m->is_native(), "cannot rewrite native methods");
   // Allocate new Method*
   AccessFlags flags = m->access_flags();
+  u2  generic_signature_index = m->generic_signature_index();
   int checked_exceptions_len = m->checked_exceptions_length();
   int localvariable_len = m->localvariable_table_length();
   int exception_table_len = m->exception_table_length();
@@ -1102,6 +1105,7 @@
                                       localvariable_len,
                                       exception_table_len,
                                       checked_exceptions_len,
+                                      generic_signature_index,
                                       m->method_type(),
                                       CHECK_(methodHandle()));
   methodHandle newm (THREAD, newm_oop);
@@ -1822,6 +1826,23 @@
   loader_data->jmethod_ids()->clear_all_methods();
 }
 
+
+// Check that this pointer is valid by checking that the vtbl pointer matches
+bool Method::is_valid_method() const {
+  if (this == NULL) {
+    return false;
+  } else if (!is_metaspace_object()) {
+    return false;
+  } else {
+    Method m;
+    // This assumes that the vtbl pointer is the first word of a C++ object.
+    // This assumption is also in universe.cpp patch_klass_vtble
+    void* vtbl2 = dereference_vptr((void*)&m);
+    void* this_vtbl = dereference_vptr((void*)this);
+    return vtbl2 == this_vtbl;
+  }
+}
+
 #ifndef PRODUCT
 void Method::print_jmethod_ids(ClassLoaderData* loader_data, outputStream* out) {
   out->print_cr("jni_method_id count = %d", loader_data->jmethod_ids()->count_methods());
@@ -1943,7 +1964,7 @@
   guarantee(constMethod()->is_metadata(), "should be metadata");
   MethodData* md = method_data();
   guarantee(md == NULL ||
-      md->is_metadata(), "should be in permspace");
+      md->is_metadata(), "should be metadata");
   guarantee(md == NULL ||
       md->is_methodData(), "should be method data");
 }