Is OSCompareAndSwap (Mac OS X) equivalent to CMPXCHG8B?

Is OSCompareAndSwa开发者_如何学Gop (Mac OS X) equivalent to CMPXCHG8B?

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You can find the definition of the atomic functions in the OSAtomic.s file in the XNU source. For example, here's OSAtomicCompareAndSwapPtr for x86_64 in version 1486.2.11:

_OSCompareAndSwap64:
_OSCompareAndSwapPtr: #;oldValue, newValue, ptr
    movq         %rdi, %rax
    lock
    cmpxchgq    %rsi, 0(%rdx)   #; CAS (eax is an implicit operand)
    sete        %al             #; did CAS succeed? (TZ=1)
    movzbq      %al, %rax       #; clear out the high bytes
    ret

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lock cmpxchg8b

more exactly

It's for intel processors, but take into account, that osx exists not only for intel architecture, so asm will be different