src/share/vm/gc/shared/threadLocalAllocBuffer.cpp

@@ -1,7 +1,7 @@
 /*
- * Copyright (c) 1999, 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1999, 2017, 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.

@@ -40,10 +40,12 @@
 unsigned         ThreadLocalAllocBuffer::_target_refills = 0;
 GlobalTLABStats* ThreadLocalAllocBuffer::_global_stats   = NULL;
 
 void ThreadLocalAllocBuffer::clear_before_allocation() {
   _slow_refill_waste += (unsigned)remaining();
+  assert(!ZapUnusedHeapArea || _reserve_for_allocation_prefetch > 0 || 
+    top() == NULL || *(intptr_t*)top() != 0, "overzeroing detected"); 
   make_parsable(true);   // also retire the TLAB
 }
 
 void ThreadLocalAllocBuffer::accumulate_statistics_before_gc() {
   global_stats()->initialize();