[llvm] [LV, VP]VP intrinsics support for the Loop Vectorizer + adding new tail-folding mode using EVL. (PR #76172)

[Alexey Bataev via llvm-commits]

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@@ -242,6 +242,12 @@ struct VPTransformState {
   ElementCount VF;
   unsigned UF;
 
+  /// If EVL is not nullptr, then EVL must be a valid value set during plan
+  /// transformation, possibly a default value = whole vector register length.
+  /// EVL is created only if TTI prefers predicated vectorization, thus if EVL
+  /// is not nullptr it also implies preference for predicated vectorization.
+  VPValue *EVL = nullptr;
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alexey-bataev wrote:

Added TODO to remove this once the recipes properly handle EVL.

https://github.com/llvm/llvm-project/pull/76172