*** old/src/share/vm/oops/methodCounters.hpp	Tue May  6 15:13:02 2014
--- new/src/share/vm/oops/methodCounters.hpp	Tue May  6 15:13:02 2014

*** 29,38 ****
--- 29,47 ----
  #include "interpreter/invocationCounter.hpp"
  
  class MethodCounters: public MetaspaceObj {
   friend class VMStructs;
   private:
+   // NMethod age is a counter for warm methods detection in the code cache sweeper.
+   // The counter is reset by the sweeper and is decremented by some of the compiled
+   // code. The counter values are interpreted as follows:
+   // 1. (HotMethodDetection..INT_MAX] - initial value, no counters inserted
+   // 2. (1..HotMethodDetectionLimit)  - the method is warm, the counter is used
+   //                                    to figure out which methods can be flushed.
+   // 3. (INT_MIN..0]                  - method is hot and will deopt and get
+   //                                    recompiled without the counters
+   int               _nmethod_age;
    int               _interpreter_invocation_count; // Count of times invoked (reused as prev_event_count in tiered)
    u2                _interpreter_throwout_count; // Count of times method was exited via exception while interpreting
    u2                _number_of_breakpoints;      // fullspeed debugging support
    InvocationCounter _invocation_counter;         // Incremented before each activation of the method - used to trigger frequency-based optimizations
    InvocationCounter _backedge_counter;           // Incremented before each backedge taken - used to trigger frequencey-based optimizations

*** 40,59 ****
--- 49,73 ----
  #ifdef TIERED
    float             _rate;                        // Events (invocation and backedge counter increments) per millisecond
    jlong             _prev_time;                   // Previous time the rate was acquired
  #endif
  
!   MethodCounters() : _interpreter_invocation_count(0),
!   MethodCounters() : _nmethod_age(INT_MAX),
+                      _interpreter_invocation_count(0),
                       _interpreter_throwout_count(0),
                       _number_of_breakpoints(0)
  #ifdef TIERED
                     , _rate(0),
                       _prev_time(0)
  #endif
    {
      invocation_counter()->init();
      backedge_counter()->init();
+ 
+     if (StressCodeAging) {
+       set_nmethod_age(HotMethodDetectionLimit);
+     }
    }
  
   public:
    static MethodCounters* allocate(ClassLoaderData* loader_data, TRAPS);
  

*** 102,111 ****
--- 116,143 ----
  
    // invocation counter
    InvocationCounter* invocation_counter() { return &_invocation_counter; }
    InvocationCounter* backedge_counter()   { return &_backedge_counter; }
  
+   int nmethod_age() {
+     return _nmethod_age;
+   }
+   void set_nmethod_age(int age) {
+     _nmethod_age = age;
+   }
+   void reset_nmethod_age() {
+     set_nmethod_age(HotMethodDetectionLimit);
+   }
+ 
+   static bool is_nmethod_hot(int age)       { return age <= 0; }
+   static bool is_nmethod_warm(int age)      { return age < HotMethodDetectionLimit; }
+   static bool is_nmethod_age_unset(int age) { return age > HotMethodDetectionLimit; }
+   static bool should_nmethod_age(int age);
+   static ByteSize nmethod_age_offset() {
+     return byte_offset_of(MethodCounters, _nmethod_age);
+   }
+ 
    static ByteSize interpreter_invocation_counter_offset() {
      return byte_offset_of(MethodCounters, _interpreter_invocation_count);
    }
  
    static ByteSize invocation_counter_offset()    {