Mercurial > hg > truffle

comparison src/share/vm/oops/symbol.hpp @ 11033:d9eed26d638a

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
8009575: Reduce Symbol::_refcount from 4 bytes to 2 bytes Summary: Added Atomic::inc(short*) to support this change. Reviewed-by: coleenp, dcubed, dholmes, minqi
author iklam
date Sun, 23 Jun 2013 22:08:28 -0700
parents 63e54c37ac64
children 9758d9f36299
comparison
equal deleted inserted replaced
11032:b7bc7c94b4b5 11033:d9eed26d638a
25 #ifndef SHARE_VM_OOPS_SYMBOL_HPP 25 #ifndef SHARE_VM_OOPS_SYMBOL_HPP
26 #define SHARE_VM_OOPS_SYMBOL_HPP 26 #define SHARE_VM_OOPS_SYMBOL_HPP
27 27
28 #include "utilities/utf8.hpp" 28 #include "utilities/utf8.hpp"
29 #include "memory/allocation.hpp" 29 #include "memory/allocation.hpp"
30 #include "runtime/atomic.hpp"
30 31
31 // A Symbol is a canonicalized string. 32 // A Symbol is a canonicalized string.
32 // All Symbols reside in global SymbolTable and are reference counted. 33 // All Symbols reside in global SymbolTable and are reference counted.
33 34
34 // Reference counting 35 // Reference counting
99 // This cannot be inherited from ResourceObj because it cannot have a vtable. 100 // This cannot be inherited from ResourceObj because it cannot have a vtable.
100 // Since sometimes this is allocated from Metadata, pick a base allocation 101 // Since sometimes this is allocated from Metadata, pick a base allocation
101 // type without virtual functions. 102 // type without virtual functions.
102 class ClassLoaderData; 103 class ClassLoaderData;
103 104
104 class Symbol : public MetaspaceObj { 105 // We separate the fields in SymbolBase from Symbol::_body so that
106 // Symbol::size(int) can correctly calculate the space needed.
107 class SymbolBase : public MetaspaceObj {
108 public:
109 ATOMIC_SHORT_PAIR(
110 volatile short _refcount, // needs atomic operation
111 unsigned short _length // number of UTF8 characters in the symbol (does not need atomic op)
112 );
113 int _identity_hash;
114 };
115
116 class Symbol : private SymbolBase {
105 friend class VMStructs; 117 friend class VMStructs;
106 friend class SymbolTable; 118 friend class SymbolTable;
107 friend class MoveSymbols; 119 friend class MoveSymbols;
108 private: 120 private:
109 volatile int _refcount;
110 int _identity_hash;
111 unsigned short _length; // number of UTF8 characters in the symbol
112 jbyte _body[1]; 121 jbyte _body[1];
113 122
114 enum { 123 enum {
115 // max_symbol_length is constrained by type of _length 124 // max_symbol_length is constrained by type of _length
116 max_symbol_length = (1 << 16) -1 125 max_symbol_length = (1 << 16) -1
117 }; 126 };
118 127
119 static int size(int length) { 128 static int size(int length) {
120 size_t sz = heap_word_size(sizeof(Symbol) + (length > 0 ? length - 1 : 0)); 129 size_t sz = heap_word_size(sizeof(SymbolBase) + (length > 0 ? length : 0));
121 return align_object_size(sz); 130 return align_object_size(sz);
122 } 131 }
123 132
124 void byte_at_put(int index, int value) { 133 void byte_at_put(int index, int value) {
125 assert(index >=0 && index < _length, "symbol index overflow"); 134 assert(index >=0 && index < _length, "symbol index overflow");