Function _mm_maskz_rsqrt_sh

Compute the approximate reciprocal square root of the lower half-precision (16-bit) floating-point element in b, store the result in the lower element of dst using zeromask k (the element is zeroed out when mask bit 0 is not set), and copy the upper 7 packed elements from a to the upper elements of dst. The maximum relative error for this approximation is less than 1.5*2^-12.

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