[llvm] [LV] Add initial support for partial alias masking (PR #177599)

[Gaëtan Bossu via llvm-commits]

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@@ -300,9 +300,13 @@ class LoopVectorizationLegality {
   /// masking.
   bool canFoldTailByMasking() const;
 
+  /// Returns true if we can vectorize this loop with a possibly loop-invariant
+  /// mask.
+  bool canMaskLoop() const;
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gbossu wrote:

Curious: Why is "with a possible loop-invariant mask" important to point out? I think we are just checking whether all instructions can be predicated or speculated here.

https://github.com/llvm/llvm-project/pull/177599