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src/hotspot/share/oops/markWord.hpp

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@@ -38,11 +38,11 @@
  //  --------
  //             hash:25 ------------>| age:4  unused_gap:1  lock:2 (normal object)
  //
  //  64 bits:
  //  --------
- //  unused:25 hash:31 -->| unused_gap:1  age:4  unused_gap:1  lock:2 (normal object)
+ //  nklass:32 hash:25 -->| unused_gap:1  age:4  unused_gap:1  lock:2 (normal object)
  //
  //  - hash contains the identity hash value: largest value is
  //    31 bits, see os::random().  Also, 64-bit vm's require
  //    a hash value no bigger than 32 bits because they will not
  //    properly generate a mask larger than that: see library_call.cpp

@@ -99,26 +99,39 @@
    uintptr_t value() const { return _value; }
  
    // Constants
    static const int age_bits                       = 4;
    static const int lock_bits                      = 2;
-   static const int first_unused_gap_bits          = 1;
-   static const int max_hash_bits                  = BitsPerWord - age_bits - lock_bits - first_unused_gap_bits;
-   static const int hash_bits                      = max_hash_bits > 31 ? 31 : max_hash_bits;
-   static const int second_unused_gap_bits         = LP64_ONLY(1) NOT_LP64(0);
+   static const int self_forwarded_bits            = 1;
+   static const int max_hash_bits                  = BitsPerWord - age_bits - lock_bits - self_forwarded_bits;
+   static const int hash_bits                      = max_hash_bits > 25 ? 25 : max_hash_bits;
+ #ifdef _LP64
+   static const int klass_bits                     = 32;
+ #endif
  
    static const int lock_shift                     = 0;
-   static const int age_shift                      = lock_bits + first_unused_gap_bits;
-   static const int hash_shift                     = age_shift + age_bits + second_unused_gap_bits;
+   static const int self_forwarded_shift           = lock_shift + lock_bits;
+   static const int age_shift                      = self_forwarded_shift + self_forwarded_bits;
+   static const int hash_shift                     = age_shift + age_bits;
+ #ifdef _LP64
+   static const int klass_shift                    = hash_shift + hash_bits;
+ #endif
  
    static const uintptr_t lock_mask                = right_n_bits(lock_bits);
    static const uintptr_t lock_mask_in_place       = lock_mask << lock_shift;
+   static const uintptr_t self_forwarded_mask      = right_n_bits(self_forwarded_bits);
+   static const uintptr_t self_forwarded_mask_in_place = self_forwarded_mask << self_forwarded_shift;
    static const uintptr_t age_mask                 = right_n_bits(age_bits);
    static const uintptr_t age_mask_in_place        = age_mask << age_shift;
    static const uintptr_t hash_mask                = right_n_bits(hash_bits);
    static const uintptr_t hash_mask_in_place       = hash_mask << hash_shift;
  
+ #ifdef _LP64
+   static const uintptr_t klass_mask               = right_n_bits(klass_bits);
+   static const uintptr_t klass_mask_in_place      = klass_mask << klass_shift;
+ #endif
+ 
    static const uintptr_t locked_value             = 0;
    static const uintptr_t unlocked_value           = 1;
    static const uintptr_t monitor_value            = 2;
    static const uintptr_t marked_value             = 3;
  

@@ -229,10 +242,19 @@
  
    bool has_no_hash() const {
      return hash() == no_hash;
    }
  
+ #ifdef _LP64
+   inline Klass* klass() const;
+   inline Klass* klass_or_null() const;
+   inline Klass* safe_klass() const;
+   inline markWord set_klass(const Klass* klass) const;
+   inline narrowKlass narrow_klass() const;
+   inline markWord set_narrow_klass(const narrowKlass klass) const;
+ #endif
+ 
    // Prototype mark for initialization
    static markWord prototype() {
      return markWord( no_hash_in_place | no_lock_in_place );
    }
  

@@ -242,10 +264,18 @@
    // Prepare address of oop for placement into mark
    inline static markWord encode_pointer_as_mark(void* p) { return from_pointer(p).set_marked(); }
  
    // Recover address of oop from encoded form used in mark
    inline void* decode_pointer() { return (void*)clear_lock_bits().value(); }
+ 
+   inline bool self_forwarded() const {
+     return mask_bits(value(), self_forwarded_mask_in_place) != 0;
+   }
+ 
+   inline markWord set_self_forwarded() const {
+     return markWord(value() | self_forwarded_mask_in_place | marked_value);
+   }
  };
  
  // Support atomic operations.
  template<>
  struct PrimitiveConversions::Translate<markWord> : public TrueType {
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