Re:Does a compiler use all x86 instructions? (2010)
by valleyer on Thursday August 25, 2016 @02:45AM
(#12357293)
The title question, not anything to do with lea. I at least have never seen a compiler emit a rdtsc. (If there is some case where it does [presumably a benchmarking mode?] I'd be interested to hear of it.)
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Re:Does a compiler use all x86 instructions? (2010)
by rdtsc on Thursday August 25, 2016 @10:44AM
(#12359372)
Heh ;-) I see.
Hmm, can't see it being emitted unless used in profiling code. But then as an inline assembly.
Now rdtscp (notice the "p" at the end) is a fencing instruction as well! So I can see someone using that for barriers or when doing serialization.
(Or I guess if a language somehow include getting a fast spinning counter as a feature that could end up as rdtsc* instruction).