[llvm] [VPlan] Simplify BLEND %a, %b, NOT(%m) -> BLEND %b, %a, %m. (PR #128375)

[via llvm-commits]

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@@ -319,10 +317,9 @@ define void @bug18724(i1 %cond, ptr %ptr, i1 %cond.2, i64 %v.1, i32 %v.2) {
 ; VEC-NEXT:    [[N_MOD_VF:%.*]] = urem i64 [[TMP4]], 2
 ; VEC-NEXT:    [[N_VEC:%.*]] = sub i64 [[TMP4]], [[N_MOD_VF]]
 ; VEC-NEXT:    [[IND_END:%.*]] = add i64 [[V_1]], [[N_VEC]]
+; VEC-NEXT:    [[TMP5:%.*]] = insertelement <2 x i32> zeroinitializer, i32 [[V_2:%.*]], i32 0
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ayalz wrote:

nit: this can probably stay in its place(?)

https://github.com/llvm/llvm-project/pull/128375