[llvm] [LV] Prevent `extract-lane` generate unused IRs with single vector operand. (PR #172798)

[Florian Hahn via llvm-commits]

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@@ -3868,6 +3868,19 @@ void VPlanTransforms::convertToConcreteRecipes(VPlan &Plan) {
         continue;
       }
 
+      // Lower ExtractLane with single source to ExtractElement.
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fhahn wrote:

is there a reason to handle this here instead of simplifyRecipe?

https://github.com/llvm/llvm-project/pull/172798