Revision 392a4d5b include/qemu/atomic.h

b/include/qemu/atomic.h
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#endif
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#ifndef atomic_xchg


  		





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#ifdef __ATOMIC_SEQ_CST


  		





  
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#if defined(__clang__)


  		





  
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#define atomic_xchg(ptr, i)    __sync_swap(ptr, i)


  		





  
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#elif defined(__ATOMIC_SEQ_CST)


  		





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#define atomic_xchg(ptr, i)    ({                           \


  		





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    typeof(*ptr) _new = (i), _old;                          \


  		





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    __atomic_exchange(ptr, &_new, &_old, __ATOMIC_SEQ_CST); \


  		





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    _old;                                                   \


  		





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})


  		





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#elif defined __clang__


  		





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#define atomic_xchg(ptr, i)    __sync_exchange(ptr, i)


  		





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#else


  		





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/* __sync_lock_test_and_set() is documented to be an acquire barrier only.  */


  		





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#define atomic_xchg(ptr, i)    (smp_mb(), __sync_lock_test_and_set(ptr, i))


  		












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