[llvm] [VPlan] Hook IR blocks into VPlan during skeleton creation (NFC) (PR #114292)

[via llvm-commits]

================
@@ -3757,14 +3763,10 @@ class VPlan {
   friend class VPlanPrinter;
   friend class VPSlotTracker;
 
-  /// Hold the single entry to the Hierarchical CFG of the VPlan, i.e. the
-  /// preheader of the vector loop.
-  VPBasicBlock *Entry;
-
   /// VPBasicBlock corresponding to the original preheader. Used to place
   /// VPExpandSCEV recipes for expressions used during skeleton creation and the
   /// rest of VPlan execution.
----------------
ayalz wrote:

This holds for main loop vectorization only. For epilog loop vectorization the definition of Entry should documented differently.

https://github.com/llvm/llvm-project/pull/114292