[RISCV] Move vmv.v.v peephole from SelectionDAG to RISCVVectorPeephole (#100367)

This is split off from #71764, and moves only the vmv.v.v part of
performCombineVMergeAndVOps to work on MachineInstrs.

In retrospect trying to handle PseudoVMV_V_V and PseudoVMERGE_VVM in the
same function makes the code quite hard to read, so this just does it in
a separate peephole.

This turns out to be simpler since for PseudoVMV_V_V we don't need to
convert the Src instruction to a masked variant, and we don't need to
create a fake all ones mask.

0 files changed, 0 insertions, 0 deletions