[llvm] [AMDGPU] Extended vector promotion to aggregate types. (PR #143784)

[Shilei Tian via llvm-commits]

================
@@ -818,6 +818,39 @@ static BasicBlock::iterator skipToNonAllocaInsertPt(BasicBlock &BB,
   return I;
 }
 
+/// Get the underlying type of a homogeneous aggregate type, or nullptr if the
+/// type is non-homogeneous.
+static Type *getHomogeneousType(Type *Ty) {
+  Type *ElemTy = nullptr;
+  SmallVector<Type *> WorkList;
+  WorkList.push_back(Ty);
+  while (!WorkList.empty()) {
+    Type *CurTy = WorkList.pop_back_val();
+
+    // Check if the current type is an aggregate type.
+    if (auto *VectorTy = dyn_cast<FixedVectorType>(CurTy)) {
+      WorkList.push_back(VectorTy->getElementType());
+      continue;
+    }
+    if (auto *ArrayTy = dyn_cast<ArrayType>(CurTy)) {
+      WorkList.push_back(ArrayTy->getElementType());
+      continue;
+    }
+    if (auto *StructTy = dyn_cast<StructType>(CurTy)) {
+      WorkList.append(StructTy->element_begin(), StructTy->element_end());
----------------
shiltian wrote:

nit: not sure if the following change works:
```suggestion
      WorkList.append(StructTy->elements());
```

https://github.com/llvm/llvm-project/pull/143784