[DAG][RISCV] Use vp.<binop> when widening illegal types for binops which can trap (#105214)

This allows the use a single wider operation with a restricted EVL
instead of having to split and cover via decreasing powers-of-two sizes.

On RISCV, this avoids the need for a bunch of vslidedown and vslideup
instructions to extract subvectors, and VL toggles to switch between the
various widths.

Note there is a potential downside of using vp nodes; we loose any
generic DAG combines which might have applied to the split form.

0 files changed, 0 insertions, 0 deletions