[llvm] [LV] Prevent query the computeCost() when VF=1 in emitInvalidCostRemarks(). (PR #117288)

[Elvis Wang via llvm-commits]

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@@ -4372,6 +4372,9 @@ void LoopVectorizationPlanner::emitInvalidCostRemarks(
   SmallVector<RecipeVFPair> InvalidCosts;
   for (const auto &Plan : VPlans) {
     for (ElementCount VF : Plan->vectorFactors()) {
+      if (VF.isScalar())
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ElvisWang123 wrote:

Updated comments.

Currently, we cannot query the vplan-based cost model with scalar VF because we use lots of `cast<VectorType>(toVectorTy(SrcTy, VF))` in `computeCost()`. 

https://github.com/llvm/llvm-project/pull/117288