src/hotspot/share/gc/shared/barrierSetNMethod.cpp

rev 58823 : [mq]: aarch64-jdk-nmethod-barriers-3.patch

@@ -1,7 +1,7 @@
 /*
- * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2018, 2020, 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
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.

@@ -60,10 +60,20 @@
   }
 
   assert(!nm->is_osr_method(), "Should not reach here");
   // Called upon first entry after being armed
   bool may_enter = bs_nm->nmethod_entry_barrier(nm);
+
+  // Diagnostic option to force deoptimization 1 in 3 times. It is otherwise
+  // a very rare event.
+  if (DeoptimizeNMethodBarriersALot) {
+    static volatile uint32_t counter=0;
+    if (Atomic::add(&counter, 1u) % 3 == 0) {
+      may_enter = false;
+    }
+  }
+
   if (!may_enter) {
     log_trace(nmethod, barrier)("Deoptimizing nmethod: " PTR_FORMAT, p2i(nm));
     bs_nm->deoptimize(nm, return_address_ptr);
   }
   return may_enter ? 0 : 1;