Function permute2 

fn permute2<'tcx>(
    ecx: &mut MiriInterpCx<'tcx>,
    left: &OpTy<'tcx>,
    indices: &OpTy<'tcx>,
    right: &OpTy<'tcx>,
    dest: &MPlaceTy<'tcx>,
) -> InterpResult<'tcx, ()>

Shuffle elements from two source registers (left and right) using the corresponding index in indices, and store the results in dest.

For indexing, we basically concatenate left and right, and index into the concatenation. More precisely: For a vector with N lanes, the low log2(N) bits of each index select a lane within a source vector. Bit log2(N) selects the source vector (0 => left, 1 => right), and all higher bits are ignored. Equivalently, lane i of the result is copied from src[indices[i] & (N - 1)] where src = if indices[i] & N == 0 { left } else { right }.

https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_mm512_permutex2var_epi64 https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html#text=_mm512_permutex2var_epi8