On 10/28/2013 2:33 AM, eles wrote:
(For example, what really happens with a+=1 ? Should it generate an INC, or an
ADD, or a MOV/ADD/MOV triple for MMIO? Where do the barriers go? Do you even
need barriers? Should a LOCK prefix be emitted? How is the compiler supposed
to know just how the MMIO works on some particular computer board?)
read [address] into registry (mov)
registry++ (add)
write registry to [address] (mov)
You cannot do it otherwise (that is, a shortcut operator).
That overlooks what happens if another thread changes the memory in between the
read and the write. Hence the issues of memory barriers, lock prefixes, etc.
Since we discuss this matter, it could have been solved 10 times.
Pull requests are welcome!
