[llvm] [LV][EVL] Skip tryAddExplicitVectorLength for plans with scalar VF. (PR #125497)

[Luke Lau via llvm-commits]

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@@ -8933,14 +8933,15 @@ void LoopVectorizationPlanner::buildVPlansWithVPRecipes(ElementCount MinVF,
   for (ElementCount VF = MinVF; ElementCount::isKnownLT(VF, MaxVFTimes2);) {
     VFRange SubRange = {VF, MaxVFTimes2};
     if (auto Plan = tryToBuildVPlanWithVPRecipes(SubRange)) {
+      bool HasScalarVF = Plan->hasVF(ElementCount::getFixed(1));
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lukel97 wrote:

Is it possible to have a plan with both scalar and non scalar VFs? Could we use `Plan->hasScalarVFOnly()`

https://github.com/llvm/llvm-project/pull/125497