[llvm] [VPlan] Add transformation to narrow interleave groups. (PR #106441)

[via llvm-commits]

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@@ -7487,6 +7487,9 @@ LoopVectorizationPlanner::executePlan(
 
   VPlanTransforms::optimizeForVFAndUF(BestVPlan, BestVF, BestUF, PSE);
 
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ayalz wrote:

Should `optimizeForVFAndUF()` above be renamed `eliminateRedundantBranchOnCount()`?
Otherwise `narrowInterleaveGroups()` below would consistently be `optimizeForVF()`.

https://github.com/llvm/llvm-project/pull/106441