src/hotspot/share/runtime/lockStack.hpp

*** 30,14 ***
--- 30,16 ---
  #include "oops/oopsHierarchy.hpp"
  #include "utilities/globalDefinitions.hpp"
  #include "utilities/sizes.hpp"
  
  class JavaThread;
+ class ObjectMonitor;
  class OopClosure;
  class outputStream;
  template<typename>
  class GrowableArray;
+ class Thread;
  
  class LockStack {
    friend class LockStackTest;
    friend class VMStructs;
    JVMCI_ONLY(friend class JVMCIVMStructs;)

*** 121,6 ***
--- 123,31 ---
  
    // Printing
    void print_on(outputStream* st);
  };
  
+ class OMCache {
+   friend class VMStructs;
+ public:
+   static constexpr int CAPACITY = 8;
+ 
+ private:
+   struct OMCacheEntry {
+     oop _oop = nullptr;
+     ObjectMonitor* _monitor = nullptr;
+   } _entries[CAPACITY];
+   const oop _null_sentinel = nullptr;
+ 
+ public:
+   static ByteSize entries_offset() { return byte_offset_of(OMCache, _entries); }
+   static constexpr ByteSize oop_to_oop_difference() { return in_ByteSize(sizeof(OMCacheEntry)); }
+   static constexpr ByteSize oop_to_monitor_difference() { return in_ByteSize(sizeof(oop)); }
+ 
+   explicit OMCache(JavaThread* jt);
+ 
+   inline ObjectMonitor* get_monitor(oop o);
+   inline void set_monitor(ObjectMonitor* monitor);
+   inline void clear();
+ 
+ };
+ 
  #endif // SHARE_RUNTIME_LOCKSTACK_HPP