The current behaviour on other platforms support vecatorization of `fd_1 bop fd_2 ? res_1 : res_2` in a loop only when `fd` and `res` have the same size, but this constraint seems not necessary at least not necessary on riscv, so I relax this constraint on riscv, maybe on other platforms it can be relaxed too, but currently I only made it work on riscv.
Besides of this, I also relax the constraint on transforming Op_CMoveI/L to Op_VectorBlend on riscv.
Both relaxations bring performance benefit via vectorization (on riscv).