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

[Benjamin Maxwell via llvm-commits]

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@@ -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) {
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MacDue wrote:

> Also, is there any downside to always creating the `mul`? 

It creates more bloat in the test size/churn. This function was created to match `createStepForVF` which also just does `Step * VF` but tries to "optimize" some cases. 



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