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

[Florian Hahn 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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fhahn wrote:

Sorry if it has not been clear from my coment above, I meant only trying to remove `VPUnrollPartAccessor` from `VPInstruction`, by replacing the part operand added here by creating VPInstruction here for `(zext/trunc VF to Ty) * Part` and add this as operand instead, so we don't need to lookup the part and scale during `::execute` at all. And example of a similar cleanup would be https://github.com/llvm/llvm-project/pull/172372.

If that is not trivial, better to leave out of the PR.

`VPUnrollPartAccessor` is a temporary measure, and remaining users are slowly migrated to be handled explicitly during unrolling, which enables further optimizations, and will allow to eventually remove the need for `VPUnrollPartAccessor` alltogether. I don't think we should change `VPUnrollPartAccessor` itself.



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