3 ms·
0F 1A and 0F 1B have recently become memory bound verification instructions, as part of MPX. So really, only 0F 1F is likely to be long-term safe to use as a mu
by pbsd 10y ago
0F 1A and 0F 1B have recently become memory bound verification instructions, as part of MPX. So really, only 0F 1F is likely to be long-term safe to use as a multibyte NOP.
Likewise, after Pentium 4 REP NOP (F3 90) became PAUSE, the spinlock waiting hint instruction, so one needs to be careful about prefixes with the old NOP as well.
- xorblurb 10y agoAlthough PAUSE only has a performance impact, it was part of its design (so you need only one binary for your spinlock, and it executes correctly even on processor who don't know anything about PAUSE)