[llvm] [VPlan] Extend getSCEVForVPV, use to compute VPReplicateRecipe cost. (PR #161276)

[Florian Hahn via llvm-commits]

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@@ -86,6 +87,85 @@ const SCEV *vputils::getSCEVExprForVPValue(VPValue *V, ScalarEvolution &SE) {
   return TypeSwitch<const VPRecipeBase *, const SCEV *>(V->getDefiningRecipe())
       .Case<VPExpandSCEVRecipe>(
           [](const VPExpandSCEVRecipe *R) { return R->getSCEV(); })
+      .Case<VPCanonicalIVPHIRecipe>([&SE, L](const VPCanonicalIVPHIRecipe *R) {
+        if (!L)
+          return SE.getCouldNotCompute();
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fhahn wrote:

Yep, a loop is only needed if we need to construct a SCEVAddRecExpr, which should only happen here

https://github.com/llvm/llvm-project/pull/161276