Is OSCompareAndSwap (Mac OS X) equivalent to CMPXCHG8B?
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21-09-2019 - |
문제
Is OSCompareAndSwap (Mac OS X) equivalent to CMPXCHG8B?
해결책
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
다른 팁
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
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