[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) {
----------------
bogner wrote:

This name is a bit misleading - the function is answering the question "does the struct containing only vectors, and are all of those vectors the same size?". Not sure how best to convey that concisely - maybe "isStructOfMatchingFixedVectors" or something?

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