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

[Sander de Smalen via llvm-commits]

================
@@ -788,6 +788,13 @@ Value *createStepForVF(IRBuilderBase &B, Type *Ty, ElementCount VF,
   return B.CreateElementCount(Ty, VFxStep);
 }
 
+Value *createStep(IRBuilderBase &B, Type *Ty, Value *StepSize, int64_t Step) {
----------------
sdesmalen-arm wrote:

The name confuses me, because it suggests it creates a Step value, but in reality it merely generates a multiply (possibly with trunc/ext). Also, is there any downside to always creating the `mul`? (I expect this to be optimised away later) If not, then I'd suggest always just inlining the `CreateMul` and removing this utility function.

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