[llvm] [VPlan] Make canonical IV part of the region (PR #156262)

[via llvm-commits]

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@@ -8338,8 +8338,7 @@ VPlanPtr LoopVectorizationPlanner::tryToBuildVPlanWithVPRecipes(
       // latter are added above for masking.
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ayalz wrote:

Replace "including canonical IV," above with "including blends,"

https://github.com/llvm/llvm-project/pull/156262