src/hotspot/share/oops/oop.hpp

@@ -73,10 +73,11 @@
    inline markWord  mark_acquire()  const;
    inline markWord* mark_addr() const;
  
    inline void set_mark(markWord m);
    static inline void set_mark(HeapWord* mem, markWord m);
+   inline void set_mark_full(markWord m);
    static inline void release_set_mark(HeapWord* mem, markWord m);
  
    inline void release_set_mark(markWord m);
    inline markWord cas_set_mark(markWord new_mark, markWord old_mark);
    inline markWord cas_set_mark(markWord new_mark, markWord old_mark, atomic_memory_order order);

@@ -114,13 +115,36 @@
    inline bool is_a(Klass* k) const;
  
    // Returns the actual oop size of the object in machine words
    inline size_t size();
  
+   // Returns the size that a copy of this object requires, in machine words.
+   // It can be 1 word larger than its current size to accomodate
+   // an additional 4-byte-field for the identity hash-code.
+   //
+   // size: the current size of this object, we're passing this here for performance
+   //       reasons, because all callers compute this anyway, and we want to avoid
+   //       recomputing it.
+   // mark: the mark-word of this object. Some callers (e.g. G1ParScanThreadState::do_copy_to_survivor_space())
+   //       need to use a known markWord because of racing GC threads that can change
+   //       the markWord at any time.
+   inline size_t copy_size(size_t size, markWord mark) const;
+   // Special version to deal with scratch classes in CDS. There we allocate
+   // temporary scratch classes (which are skeleton versions of InstanceMirrorKlass,
+   // which represent java.lang.Class objects in the CDS archive). At that point, we
+   // don't know whether or not the final archived version will be hashed or expanded,
+   // and therefore we allocate them in the special state not-hashed-but-expanded.
+   // When creating the final copy of those objects, we either populate the hidden hash
+   // field and make the object 'expanded', or we turn it back to 'not-hashed'
+   // and reduce the object's size. We do this by providing a separate method for CDS
+   // so that we don't affect GC performance.
+   inline size_t copy_size_cds(size_t size, markWord mark) const;
+ 
    // Sometimes (for complicated concurrency-related reasons), it is useful
    // to be able to figure out the size of an object knowing its klass.
-   inline size_t size_given_klass(Klass* klass);
+   inline size_t base_size_given_klass(markWord m, const Klass* klass);
+   inline size_t size_given_mark_and_klass(markWord mrk, const Klass* kls);
  
    // type test operations (inlined in oop.inline.hpp)
    inline bool is_instance()    const;
    inline bool is_instanceRef() const;
    inline bool is_stackChunk()  const;

@@ -314,10 +338,16 @@
    // identity hash; returns the identity hash key (computes it if necessary)
    inline intptr_t identity_hash();
    intptr_t slow_identity_hash();
    inline bool fast_no_hash_check();
  
+   // Initialize identity hash code in hash word of object copy from original object.
+   // Returns true if the object has been expanded, false otherwise.
+   inline void initialize_hash_if_necessary(oop obj);
+   // For CDS only.
+   void initialize_hash_if_necessary(oop obj, Klass* k, markWord m);
+ 
    // marks are forwarded to stack when object is locked
    inline bool     has_displaced_mark() const;
    inline markWord displaced_mark() const;
    inline void     set_displaced_mark(markWord m);
  

@@ -330,24 +360,20 @@
    }
  
    // for code generation
    static int mark_offset_in_bytes()      { return (int)offset_of(oopDesc, _mark); }
    static int klass_offset_in_bytes()     {
- #ifdef _LP64
-     if (UseCompactObjectHeaders) {
-       // NOTE: The only places where this is used with compact headers are the C2
-       // compiler and JVMCI.
-       return mark_offset_in_bytes() + markWord::klass_offset_in_bytes;
-     } else
- #endif
-     {
-       return (int)offset_of(oopDesc, _metadata._klass);
-     }
+     assert(!UseCompactObjectHeaders, "don't use this with compact headers");
+     return (int)offset_of(oopDesc, _metadata._klass);
    }
    static int klass_gap_offset_in_bytes() {
      assert(has_klass_gap(), "only applicable to compressed klass pointers");
-     return klass_offset_in_bytes() + sizeof(narrowKlass);
+     if (UseCompactObjectHeaders) {
+       return base_offset_in_bytes();
+     } else {
+       return klass_offset_in_bytes() + sizeof(narrowKlass);
+     }
    }
  
    static int base_offset_in_bytes() {
      return ObjLayout::oop_base_offset_in_bytes();
    }