[llvm] [VPlan] Handle regions with live-outs and scalar VF when replicating. (PR #186252)

[via llvm-commits]

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ayalz wrote:

Related to previous patch: can the check for DefR's parent be dropped, this essentially skips values that are already single scalar wherever they are, and highlights the fact that vputils(isSingleScalar(Op)) fails to provide an accurate answer for VPScalarIVStepsRecipe. I.e., when replicating by VF, VPScalarIVStepsRecipes should transform to isSingleScalar recipes.

https://github.com/llvm/llvm-project/pull/186252