Illegal instructions don't require reshuffling

[TimLee-123]

Issue

This vmnand instruction, as observed from the waveform, appears to be an illegal instruction. Since this is an illegal instruction, there is no need to perform reshuffling for it, as it would drag down the overall performance.

Supplementary Pictures

[mp-17]

Thanks @TimLee-123,

Your findings are really appreciated. We plan to target all these bugs and optimizations with a dedicated verification effort.