src/share/vm/oops/symbol.hpp

*** 100,134 ****
  // This cannot be inherited from ResourceObj because it cannot have a vtable.
  // Since sometimes this is allocated from Metadata, pick a base allocation
  // type without virtual functions.
  class ClassLoaderData;
  
! // We separate the fields in SymbolBase from Symbol::_body so that
! // Symbol::size(int) can correctly calculate the space needed.
! class SymbolBase : public MetaspaceObj {
!  public:
!   ATOMIC_SHORT_PAIR(
!     volatile short _refcount,  // needs atomic operation
!     unsigned short _length     // number of UTF8 characters in the symbol (does not need atomic op)
!   );
!   int            _identity_hash;
! };
! 
! class Symbol : private SymbolBase {
    friend class VMStructs;
    friend class SymbolTable;
    friend class MoveSymbols;
   private:
!   jbyte _body[1];
  
    enum {
      // max_symbol_length is constrained by type of _length
      max_symbol_length = (1 << 16) -1
    };
  
    static int size(int length) {
!     size_t sz = heap_word_size(sizeof(SymbolBase) + (length > 0 ? length : 0));
      return align_object_size(sz);
    }
  
    void byte_at_put(int index, int value) {
      assert(index >=0 && index < _length, "symbol index overflow");
--- 100,129 ----
  // This cannot be inherited from ResourceObj because it cannot have a vtable.
  // Since sometimes this is allocated from Metadata, pick a base allocation
  // type without virtual functions.
  class ClassLoaderData;
  
! class Symbol : public MetaspaceObj {
    friend class VMStructs;
    friend class SymbolTable;
    friend class MoveSymbols;
+ 
   private:
!   ATOMIC_SHORT_PAIR(
!     volatile short _refcount,  // needs atomic operation
!     unsigned short _length     // number of UTF8 characters in the symbol (does not need atomic op)
!   );
!   short _identity_hash;
!   jbyte _body[2];
  
    enum {
      // max_symbol_length is constrained by type of _length
      max_symbol_length = (1 << 16) -1
    };
  
    static int size(int length) {
!     size_t sz = heap_word_size(sizeof(Symbol) + (length > 2 ? length - 2 : 0));
      return align_object_size(sz);
    }
  
    void byte_at_put(int index, int value) {
      assert(index >=0 && index < _length, "symbol index overflow");
*** 148,159 ****
  
    int size()                { return size(utf8_length()); }
  
    // Returns the largest size symbol we can safely hold.
    static int max_length()   { return max_symbol_length; }
! 
!   int identity_hash()       { return _identity_hash; }
  
    // For symbol table alternate hashing
    unsigned int new_hash(juint seed);
  
    // Reference counting.  See comments above this class for when to use.
--- 143,157 ----
  
    int size()                { return size(utf8_length()); }
  
    // Returns the largest size symbol we can safely hold.
    static int max_length()   { return max_symbol_length; }
!   unsigned identity_hash() {
!     unsigned addr_bits = (unsigned)((uintptr_t)this >> (LogMinObjAlignmentInBytes + 3));
!     return (unsigned)_identity_hash |
!            ((addr_bits ^ (_length << 8) ^ (( _body[0] << 8) | _body[1])) << 16);
!   }
  
    // For symbol table alternate hashing
    unsigned int new_hash(juint seed);
  
    // Reference counting.  See comments above this class for when to use.