[llvm] [Scalarizer][DirectX] support structs return types (PR #111569)

[Justin Bogner via llvm-commits]

================
@@ -197,6 +197,23 @@ struct VectorLayout {
   uint64_t SplitSize = 0;
 };
 
+static bool isStructAllVectors(Type *Ty) {
+  if (!isa<StructType>(Ty))
+    return false;
+  if (Ty->getNumContainedTypes() < 1)
+    return false;
+  FixedVectorType *VecTy = dyn_cast<FixedVectorType>(Ty->getContainedType(0));
+  if (!VecTy)
+    return false;
+  unsigned VecSize = VecTy->getNumElements();
+  for (unsigned I = 1; I < Ty->getNumContainedTypes(); I++) {
----------------
bogner wrote:

Generally best to cache the size here rather than call a function every iteration
```suggestion
  for (unsigned I = 1, E = Ty->getNumContainedTypes(); I != E; I++) {
```

https://github.com/llvm/llvm-project/pull/111569