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

[via llvm-commits]

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@@ -604,7 +601,7 @@ define void @pr70590_recipe_without_underlying_instr(i64 %n, ptr noalias %dst) {
 ; CHECK-NEXT:    [[TMP17:%.*]] = getelementptr [5 x i8], ptr @c, i64 0, i64 [[TMP16]]
 ; CHECK-NEXT:    [[TMP18:%.*]] = getelementptr i8, ptr [[TMP17]], i32 0
 ; CHECK-NEXT:    [[WIDE_LOAD:%.*]] = load <4 x i8>, ptr [[TMP18]], align 1
-; CHECK-NEXT:    [[PREDPHI:%.*]] = select <4 x i1> [[TMP2]], <4 x i8> [[WIDE_LOAD]], <4 x i8> zeroinitializer
+; CHECK-NEXT:    [[PREDPHI:%.*]] = select <4 x i1> [[TMP1]], <4 x i8> zeroinitializer, <4 x i8> [[WIDE_LOAD]]
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ayalz wrote:

(here the NOTed mask TMP2 has other uses so remains) 

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