--- old/src/hotspot/share/gc/shared/threadLocalAllocBuffer.hpp	2018-05-11 17:07:52.158072537 +0200
+++ new/src/hotspot/share/gc/shared/threadLocalAllocBuffer.hpp	2018-05-11 17:07:51.883060562 +0200
@@ -79,6 +79,8 @@
 
   size_t remaining() const                       { return end() == NULL ? 0 : pointer_delta(hard_end(), top()); }
 
+  bool contains(HeapWord* obj, size_t size)      { return (obj >= start()) && (obj + size <= top()); }
+
   // Make parsable and release it.
   void reset();
 
@@ -129,6 +131,9 @@
   // Allocate size HeapWords. The memory is NOT initialized to zero.
   inline HeapWord* allocate(size_t size);
 
+  // Undo last allocation.
+  inline bool undo_allocate(HeapWord* obj, size_t size);
+
   // Reserve space at the end of TLAB
   static size_t end_reserve() {
     int reserve_size = typeArrayOopDesc::header_size(T_INT);