[llvm] [VPlan] Implement interleaving as VPlan-to-VPlan transform. (PR #95842)

[via llvm-commits]

================
@@ -3665,6 +3690,29 @@ inline bool isUniformAfterVectorization(VPValue *VPV) {
     return VPI->isVectorToScalar();
   return false;
 }
+
+/// Checks if \p C is uniform across all VFs and UFs. It is considered as such
----------------
ayalz wrote:

This should probably be an analysis. Information should be assigned to each VPValue. Replicate recipes already record uniformity across VF lanes.

```suggestion
/// Checks if \p C is uniform across all VF lanes and UF parts. It is considered as such
```

https://github.com/llvm/llvm-project/pull/95842