[llvm] [LV] Add initial support for vectorizing literal struct return values (PR #109833)

[Matt Arsenault via llvm-commits]

================
@@ -5944,13 +5948,17 @@ InstructionCost LoopVectorizationCostModel::getScalarizationOverhead(
     return 0;
 
   InstructionCost Cost = 0;
-  Type *RetTy = ToVectorTy(I->getType(), VF);
+  Type *RetTy = ToWideTy(I->getType(), VF);
   if (!RetTy->isVoidTy() &&
-      (!isa<LoadInst>(I) || !TTI.supportsEfficientVectorElementLoadStore()))
-    Cost += TTI.getScalarizationOverhead(
-        cast<VectorType>(RetTy), APInt::getAllOnes(VF.getKnownMinValue()),
-        /*Insert*/ true,
-        /*Extract*/ false, CostKind);
+      (!isa<LoadInst>(I) || !TTI.supportsEfficientVectorElementLoadStore())) {
+
+    for (Type *VectorTy : getContainedTypes(RetTy)) {
+      Cost += TTI.getScalarizationOverhead(
+          cast<VectorType>(VectorTy), APInt::getAllOnes(VF.getKnownMinValue()),
+          /*Insert*/ true,
+          /*Extract*/ false, CostKind);
----------------
arsenm wrote:

```suggestion
          /*Insert=*/ true,
          /*Extract=*/ false, CostKind);
```

https://github.com/llvm/llvm-project/pull/109833