1.1 --- a/src/share/vm/runtime/atomic.hpp Fri Jun 21 10:55:26 2013 -0700
1.2 +++ b/src/share/vm/runtime/atomic.hpp Sun Jun 23 22:08:28 2013 -0700
1.3 @@ -64,11 +64,13 @@
1.4
1.5 // Atomically increment location
1.6 inline static void inc (volatile jint* dest);
1.7 + static void inc (volatile jshort* dest);
1.8 inline static void inc_ptr(volatile intptr_t* dest);
1.9 inline static void inc_ptr(volatile void* dest);
1.10
1.11 // Atomically decrement a location
1.12 inline static void dec (volatile jint* dest);
1.13 + static void dec (volatile jshort* dest);
1.14 inline static void dec_ptr(volatile intptr_t* dest);
1.15 inline static void dec_ptr(volatile void* dest);
1.16
1.17 @@ -95,4 +97,24 @@
1.18 inline static void* cmpxchg_ptr(void* exchange_value, volatile void* dest, void* compare_value);
1.19 };
1.20
1.21 +// To use Atomic::inc(jshort* dest) and Atomic::dec(jshort* dest), the address must be specially
1.22 +// aligned, such that (*dest) occupies the upper 16 bits of an aligned 32-bit word. The best way to
1.23 +// achieve is to place your short value next to another short value, which doesn't need atomic ops.
1.24 +//
1.25 +// Example
1.26 +// ATOMIC_SHORT_PAIR(
1.27 +// volatile short _refcount, // needs atomic operation
1.28 +// unsigned short _length // number of UTF8 characters in the symbol (does not need atomic op)
1.29 +// );
1.30 +
1.31 +#ifdef VM_LITTLE_ENDIAN
1.32 +#define ATOMIC_SHORT_PAIR(atomic_decl, non_atomic_decl) \
1.33 + non_atomic_decl; \
1.34 + atomic_decl
1.35 +#else
1.36 +#define ATOMIC_SHORT_PAIR(atomic_decl, non_atomic_decl) \
1.37 + atomic_decl ; \
1.38 + non_atomic_decl
1.39 +#endif
1.40 +
1.41 #endif // SHARE_VM_RUNTIME_ATOMIC_HPP
