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

[Ramkumar Ramachandra via llvm-commits]

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@@ -6917,6 +6900,12 @@ LoopVectorizationPlanner::computeBestVF() {
     }
   }
 
+  // For outer loops, the plan has a single vector VF determined by the
+  // heuristic. Return it directly since there is no scalar VF plan for cost
+  // comparison.
+  if (!OrigLoop->isInnermost())
+    return {VectorizationFactor(FirstPlan.getSingleVF(), 0, 0), &FirstPlan};
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artagnon wrote:

Is this necessary? Don't we have VPlans.size() == 1, which will match?

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