[llvm] [RISCV] Move RISCVInsertVSETVLI to after phi elimination (PR #91440)

[Piyou Chen via llvm-commits]

================
@@ -1155,8 +1155,8 @@ define void @mulhu_v8i16(ptr %x) {
 ; CHECK-NEXT:    vle16.v v8, (a0)
 ; CHECK-NEXT:    vmv.v.i v9, 0
 ; CHECK-NEXT:    lui a1, 1048568
-; CHECK-NEXT:    vsetvli zero, zero, e16, m1, tu, ma
 ; CHECK-NEXT:    vmv.v.i v10, 0
----------------
BeMg wrote:

Maybe it assume VL/VTYPE dependant doesn't break?

> NOTE:
> post-ra pseudo pass invoke `TII->lowerCOPY -> RISCVInstrInfo::copyPhysReg -> RISCVInstrInfo::copyPhysRegVector` to > emit the `PseudoVMV_V_I_M1` base on `COPY`. 



https://github.com/llvm/llvm-project/pull/91440