[llvm] [VPlan] Rename isUniform(AfterVectorization) to isSingleScalar (NFC). (PR #140134)

[via llvm-commits]

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@@ -643,12 +643,11 @@ static void legalizeAndOptimizeInductions(VPlan &Plan) {
       // Skip recipes that shouldn't be narrowed.
       if (!Def || !isa<VPReplicateRecipe, VPWidenRecipe>(Def) ||
           Def->getNumUsers() == 0 || !Def->getUnderlyingValue() ||
-          (RepR && (RepR->isUniform() || RepR->isPredicated())))
+          (RepR && (RepR->isSingleScalar() || RepR->isPredicated())))
         continue;
 
       // Skip recipes that may have other lanes than their first used.
-      if (!vputils::isUniformAfterVectorization(Def) &&
-          !vputils::onlyFirstLaneUsed(Def))
+      if (!vputils::isSingleScalar(Def) && !vputils::onlyFirstLaneUsed(Def))
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ayalz wrote:

`isSingleScalar` describes the result - a single scalar value suffices - which stems from above: how the values per lanes were defined, namely, produced equal aka uniform (or undefined for all lanes except one); and/or from below: how many values will be needed, used. Analogous to narrowing bitwidth based on value range analysis and/or demanded bits analysis.

https://github.com/llvm/llvm-project/pull/140134