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opmask register

One of AVX-512's eight small registers that hold one bit per lane, used to switch individual lanes of an instruction on or off.

The AVX-512 opmask registers k0-k7 hold up to 64 bits, one per lane; EVEX-encoded instructions take k1-k7 as a write mask ({k1} merge or {k1}{z} zero), compares write masks into them, and k0 in the mask position means no masking.

See also

AVX-512 bit mask predicate register
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