[llvm] [LV][NFC]Preselect folding style before choosing maxing VF, NFC. (PR #81885)

[Florian Hahn via llvm-commits]

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@@ -1674,8 +1684,10 @@ class LoopVectorizationCostModel {
   /// iterations to execute in the scalar loop.
   ScalarEpilogueLowering ScalarEpilogueStatus = CM_ScalarEpilogueAllowed;
 
-  /// All blocks of loop are to be masked to fold tail of scalar iterations.
-  bool CanFoldTailByMasking = false;
+  /// Control finally chosen tail folding style. The first element is used if iv
+  /// update may overflow, the second element - if it may not.
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fhahn wrote:

nit: the second element- if it does not. (May not reads as it may or may not overflow to me, but I may be wrong)

https://github.com/llvm/llvm-project/pull/81885