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

[Kerry McLaughlin via llvm-commits]

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@@ -1446,6 +1448,92 @@ static bool isConditionTrueViaVFAndUF(VPValue *Cond, VPlan &Plan,
   return SE.isKnownPredicate(CmpInst::ICMP_EQ, VectorTripCount, C);
 }
 
+static bool useWideActiveLaneMask(VPlan &Plan, ElementCount VF, unsigned UF) {
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kmclaughlin-arm wrote:

Renamed to `tryToReplaceALMWithWideALM` and added documentation.

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