[llvm] [LV] Pass symbolic VF to CalculateTripCountMinusVF and CanonicalIVIncrementForPart (NFC) (PR #180542)

[Benjamin Maxwell via llvm-commits]

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@@ -467,7 +467,7 @@ void VPlanTransforms::unrollByUF(VPlan &Plan, unsigned UF) {
         auto *VPI = dyn_cast<VPInstruction>(&R);
         if (VPI &&
             VPI->getOpcode() == VPInstruction::CanonicalIVIncrementForPart &&
-            VPI->getNumOperands() == 1) {
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MacDue wrote:

Right, thanks for clarifying :+1: I've updated this so we create `VFxPart` in `unrollRecipeByUF()`. This does require adjusting some matching (which seems a little brittle), but it seems like it all works out for the tests (aside from a little churn). 

https://github.com/llvm/llvm-project/pull/180542