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

[Luke Lau via llvm-commits]

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@@ -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
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lukel97 wrote:

Ah it actually looks for the last vsetvli to see if the SEW/VTYPE matches in `isConvertibleToVMV_V_V`. Thanks for the explanation, it makes sense to me now. The `vmv.v.i v10, 0` is a copy of the `vmv.v.i v9, 0` above. And because the `vmv.v.i v9, 0` has a TA policy, RISCVInstrInfo::copyPhysRegVector can insert the `vmv.v.i 10, 0` in either a TU or TA policy.

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