--- old/src/share/vm/oops/instanceKlass.cpp	2019-05-17 16:16:40.000000000 -0700
+++ new/src/share/vm/oops/instanceKlass.cpp	2019-05-17 16:16:40.000000000 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2019, Oracle and/or its affiliates. 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
@@ -2925,6 +2925,13 @@
 
 // On-stack replacement stuff
 void InstanceKlass::add_osr_nmethod(nmethod* n) {
+#ifndef PRODUCT
+  if (TieredCompilation) {
+      nmethod * prev = lookup_osr_nmethod(n->method(), n->osr_entry_bci(), n->comp_level(), true);
+      assert(prev == NULL || !prev->is_in_use(),
+      "redundunt OSR recompilation detected. memory leak in CodeCache!");
+  }
+#endif
   // only one compilation can be active
   NEEDS_CLEANUP
   // This is a short non-blocking critical region, so the no safepoint check is ok.
@@ -3046,7 +3053,9 @@
     osr = osr->osr_link();
   }
   OsrList_lock->unlock();
-  if (best != NULL && best->comp_level() >= comp_level && match_level == false) {
+
+  assert(match_level == false || best == NULL, "shouldn't pick up anything if match_level is set");
+  if (best != NULL && best->comp_level() >= comp_level) {
     return best;
   }
   return NULL;