[llvm] [VPlan] Retain exit conditions and edges in initial VPlan (NFC). (PR #137709)

[via llvm-commits]

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@@ -534,9 +547,6 @@ void VPlanTransforms::prepareForVectorization(VPlan &Plan, Type *InductionTy,
   }
 
   // The connection order corresponds to the operands of the conditional branch.
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ayalz wrote:

"// with middle block already connected to exit block."?

https://github.com/llvm/llvm-project/pull/137709