[llvm] [VPlan] Unify inner and outer loop paths (NFCI). (PR #192868)

[Florian Hahn via llvm-commits]

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@@ -2972,8 +2972,60 @@ void LoopVectorizationCostModel::collectLoopUniforms(ElementCount VF) {
   Uniforms[VF].insert_range(Worklist);
 }
 
+// This function will select a scalable VF if the target supports scalable
+// vectors and a fixed one otherwise.
+// TODO: we could return a pair of values that specify the max VF and
+// min VF, to be used in `buildVPlans(MinVF, MaxVF)` instead of
+// `buildVPlans(VF, VF)`. We cannot do it because VPLAN at the moment
+// doesn't have a cost model that can choose which plan to execute if
+// more than one is generated.
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fhahn wrote:

Agreed!

https://github.com/llvm/llvm-project/pull/192868