[dgacmu]

Oh, I don't think it's a general principal, it's very processor architecture specific. But here's one example from earlier avx-supporting CPUs: http://0x80.pl/articles/sse-popcount.html

[RaisingSpear]

POPCNT doesn't exist in AVX prior to Icelake, so using other techniques there is sensible. Also, that's POPCNT, not LZCNT.