[llvm] [LoopVectorize] Generate wide active lane masks (PR #147535)

[Kerry McLaughlin via llvm-commits]

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@@ -44,6 +44,7 @@ class VPRecipeBuilder;
 struct VFRange;
 
 extern cl::opt<bool> EnableVPlanNativePath;
+extern cl::opt<bool> EnableWideActiveLaneMask;
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kmclaughlin-arm wrote:

Yes, for now this is just to test the feature and keep this first patch small, but enabling it without the flag will require more work to decide whether it's beneficial to use the wider mask.

https://github.com/llvm/llvm-project/pull/147535