[llvm] [LV] Move isCandidateForEpilogueVec to LoopVectorizationPlanner.cpp (NFC). (PR #195268)

[Hassnaa Hamdi via llvm-commits]

================
@@ -618,3 +619,61 @@ void VFSelectionContext::collectInLoopReductions() {
                       << " reduction for phi: " << *Phi << "\n");
   }
 }
+
+/// Returns true if the VPlan contains header phi recipes that are not currently
+/// supported for epilogue vectorization.
+static bool hasUnsupportedHeaderPhiRecipe(VPlan &Plan) {
----------------
hassnaaHamdi wrote:

Could you also use the Doxygen syntax `\returns` 

https://github.com/llvm/llvm-project/pull/195268