On CPUs with variable instruction length, like the Intel/AMD CPUs, many programs have a lot of NOPs, which are inserted by the compiler for instruction alignmen

On CPUs with variable instruction length, like the Intel/AMD CPUs, many programs have a lot of NOPs, which are inserted by the compiler for instruction alignment. However those NOPs are seldom executed frequently, because most are outside of loop bodies. Nevertheless, there are cases when NOPs may be located inside big loops, in order to align some branch targets to cache line boundaries. That is why many recent Intel/AMD CPUs have special hardware for accelerating NOP execution, which may eliminate the NOPs before reaching the execution units.