src/share/vm/runtime/atomic.hpp

rev 11110 : 8155949: Support relaxed semantics in cmpxchg
Reviewed-by:
Contributed-by: HORII@jp.ibm.com, mdoerr

*** 25,34 ****
--- 25,40 ----
  #ifndef SHARE_VM_RUNTIME_ATOMIC_HPP
  #define SHARE_VM_RUNTIME_ATOMIC_HPP
  
  #include "memory/allocation.hpp"
  
+ typedef enum cmpxchg_cmpxchg_memory_order {
+   memory_order_relaxed,
+   // Use value which doesn't interfere with C++2011. We need to be more conservative.
+   memory_order_conservative = 8
+ } cmpxchg_memory_order;
+ 
  class Atomic : AllStatic {
   private:
    static jbyte cmpxchg_general(jbyte exchange_value, volatile jbyte* dest, jbyte compare_value);
  
   public:
*** 105,121 ****
  
    // Performs atomic compare of *dest and compare_value, and exchanges
    // *dest with exchange_value if the comparison succeeded. Returns prior
    // value of *dest. cmpxchg*() provide:
    // <fence> compare-and-exchange <membar StoreLoad|StoreStore>
!   inline static jbyte    cmpxchg    (jbyte        exchange_value, volatile jbyte*        dest, jbyte        compare_value);
!   inline static jint     cmpxchg    (jint         exchange_value, volatile jint*         dest, jint         compare_value);
    // See comment above about using jlong atomics on 32-bit platforms
!   inline static jlong    cmpxchg    (jlong        exchange_value, volatile jlong*        dest, jlong        compare_value);
!   static unsigned int    cmpxchg    (unsigned int exchange_value, volatile unsigned int* dest, unsigned int compare_value);
!   inline static intptr_t cmpxchg_ptr(intptr_t     exchange_value, volatile intptr_t*     dest, intptr_t     compare_value);
!   inline static void*    cmpxchg_ptr(void*        exchange_value, volatile void*         dest, void*        compare_value);
  };
  
  // To use Atomic::inc(jshort* dest) and Atomic::dec(jshort* dest), the address must be specially
  // aligned, such that (*dest) occupies the upper 16 bits of an aligned 32-bit word. The best way to
  // achieve is to place your short value next to another short value, which doesn't need atomic ops.
--- 111,127 ----
  
    // Performs atomic compare of *dest and compare_value, and exchanges
    // *dest with exchange_value if the comparison succeeded. Returns prior
    // value of *dest. cmpxchg*() provide:
    // <fence> compare-and-exchange <membar StoreLoad|StoreStore>
!   inline static jbyte    cmpxchg    (jbyte        exchange_value, volatile jbyte*        dest, jbyte        compare_value, cmpxchg_memory_order order = memory_order_conservative);
!   inline static jint     cmpxchg    (jint         exchange_value, volatile jint*         dest, jint         compare_value, cmpxchg_memory_order order = memory_order_conservative);
    // See comment above about using jlong atomics on 32-bit platforms
!   inline static jlong    cmpxchg    (jlong        exchange_value, volatile jlong*        dest, jlong        compare_value, cmpxchg_memory_order order = memory_order_conservative);
!   static unsigned int    cmpxchg    (unsigned int exchange_value, volatile unsigned int* dest, unsigned int compare_value, cmpxchg_memory_order order = memory_order_conservative);
!   inline static intptr_t cmpxchg_ptr(intptr_t     exchange_value, volatile intptr_t*     dest, intptr_t     compare_value, cmpxchg_memory_order order = memory_order_conservative);
!   inline static void*    cmpxchg_ptr(void*        exchange_value, volatile void*         dest, void*        compare_value, cmpxchg_memory_order order = memory_order_conservative);
  };
  
  // To use Atomic::inc(jshort* dest) and Atomic::dec(jshort* dest), the address must be specially
  // aligned, such that (*dest) occupies the upper 16 bits of an aligned 32-bit word. The best way to
  // achieve is to place your short value next to another short value, which doesn't need atomic ops.