[llvm] [LV] Support interleaving with FindLast reductions (PR #184099)

[Florian Hahn via llvm-commits]

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@@ -1294,9 +1294,11 @@ class LLVM_ABI_FOR_TEST VPInstruction : public VPRecipeWithIRFlags,
     /// Explicit user for the resume phi of the canonical induction in the main
     /// VPlan, used by the epilogue vector loop.
     ResumeForEpilogue,
-    /// Extracts the lane from the first operand corresponding to the last
-    /// active (non-zero) lane in the mask (second operand), or if no lanes
-    /// were active in the mask, returns the default value (third operand).
+    /// Extracts the last active lane from a set of vectors. The first operand
+    /// is the default value if no lanes are active. Conceptually, this
----------------
fhahn wrote:

```suggestion
    /// is the default value if no lanes in the mask are active. Conceptually, this
```

https://github.com/llvm/llvm-project/pull/184099