[llvm] [VPlan] Add VPlan-based addMinIterCheck, replace ILV for non-epilogue. (PR #153643)

[Florian Hahn via llvm-commits]

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@@ -7327,6 +7257,17 @@ DenseMap<const SCEV *, Value *> LoopVectorizationPlanner::executePlan(
       BestVPlan.resetTripCount(Exp);
     ExpSCEV->eraseFromParent();
   }
+  // SCEV expansion will add new instructions in the IRBB wrapped by Entry.
+  // Remove existing VPIRInstructions/VPIRPhi and re-create them to make sure
+  // all IR instructions are wrapped. Otherwise VPInstructions may be inserted
+  // at the wrong place.
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fhahn wrote:

I think handling expanding VPExpandSCEV recipes early and making them abstract recipes would be cleaner. As I first step, I just moved expansion in 300d2c6d2037eb5ea751bd0451d8adc2a1bd5c5d.

I updated this PR to wrap the expanded instructions (20aafa186b2d235206669424f6ef8e93a159a009), which can also be landed separately as it is NFC

https://github.com/llvm/llvm-project/pull/153643