[llvm] [RISCV][VLOPT] Add support for checkUsers when UserMI is a Single-Width Integer Reduction (PR #120345)

[Craig Topper via llvm-commits]

================
@@ -149,8 +152,11 @@ define i32 @mul_i32(<4 x i32> %a, <4 x i32> %b) {
 ; RV64-NEXT:    vslidedown.vi v10, v9, 2
 ; RV64-NEXT:    vmul.vv v9, v9, v10
 ; RV64-NEXT:    vrgather.vi v10, v8, 1
+; RV64-NEXT:    vsetivli zero, 1, e32, m1, ta, ma
 ; RV64-NEXT:    vmul.vv v8, v8, v10
+; RV64-NEXT:    vsetivli zero, 4, e32, m1, ta, ma
 ; RV64-NEXT:    vrgather.vi v10, v9, 1
+; RV64-NEXT:    vsetivli zero, 1, e32, m1, ta, ma
----------------
topperc wrote:

> Prior to this patch, isVectorOpUsedAsScalarOp was missing support for vmv.x.s. This was a bug. We'd be reducing them incorrectly if we didn't add it to isVectorOpUsedAsScalarOp.

Is there a test for that?

https://github.com/llvm/llvm-project/pull/120345