Comment by mananaysiempre

Huh, I thought they fixed that (the PCMPISTR? string instructions from SSE4.2 being significantly faster than PCMPESTR?), but looks like the explicit-length version still takes twice as many uops on recent Intel and AMD CPUs. They don’t seem to get much use nowadays anyway, though, what with being stuck in the 128-bit realm (there’s a VEX encoding but that’s basically it).