[llvm] [VPlan] Implement VPlan-based unit-strideness speculation (PR #182595)

[Mel Chen via llvm-commits]

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@@ -5601,6 +5606,10 @@ void VPlanTransforms::makeMemOpWideningDecisions(VPlan &Plan, VFRange &Range,
         });
   }
 
+  if (EnableVPlanBasedStrideMV && !CostCtx.Config.OptForSize)
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Mel-Chen wrote:

Maybe we should also consider low trip count scenarios. However, #197391 is currently removing this restriction.

https://github.com/llvm/llvm-project/pull/182595