"way more" is 2 vs 4 ports (→5 for ≥alderlake); 1/cycle via shifts is probably good enough for most use-cases (though perhaps the more focused port pressure cou

"way more" is 2 vs 4 ports (→5 for ≥alderlake); 1/cycle via shifts is probably good enough for most use-cases (though perhaps the more focused port pressure could be an issue with larger context). And with hard-coded immediates xor+sub also ends up at twice the code size as shl+shr, so there's some trade-off. (but yeah if code size isn't a concern, xor+sub wins out)