[clang] [HLSL] Add empty struct test cases to `__builtin_hlsl_is_typed_resource_element_compatible` test file (PR #115045)

[Joshua Batista via cfe-commits]

================
@@ -2200,47 +2200,43 @@ static void BuildFlattenedTypeList(QualType BaseTy,
 }
 
 bool SemaHLSL::IsTypedResourceElementCompatible(clang::QualType QT) {
-  if (QT.isNull())
+  // null and array types are not allowed.
+  if (QT.isNull() || QT->isArrayType())
     return false;
 
-  // check if the outer type was an array type
-  if (QT->isArrayType())
+  // UDT types are not allowed
+  clang::QualType CanonicalType = QT.getCanonicalType();
+  if (CanonicalType->getAs<clang::RecordType>()) {
     return false;
+  }
 
-  llvm::SmallVector<QualType, 4> QTTypes;
-  BuildFlattenedTypeList(QT, QTTypes);
+  // the only other valid builtin types are scalars or vectors
+  if (const BuiltinType *BT = CanonicalType->getAs<BuiltinType>()) {
+    if (BT->isBooleanType() || BT->isEnumeralType())
+      return false;
 
-  assert(QTTypes.size() > 0 &&
-         "expected at least one constituent type from non-null type");
-  QualType FirstQT = SemaRef.Context.getCanonicalType(QTTypes[0]);
+    int TotalSizeInBytes = SemaRef.Context.getTypeSize(BT) / 8;
 
-  // element count cannot exceed 4
-  if (QTTypes.size() > 4)
-    return false;
-
-  for (QualType TempQT : QTTypes) {
-    // ensure homogeneity
-    if (!getASTContext().hasSameUnqualifiedType(FirstQT, TempQT))
+    if (TotalSizeInBytes > 16)
       return false;
+    return true;
   }
 
-  if (const BuiltinType *BT = FirstQT->getAs<BuiltinType>()) {
-    if (BT->isBooleanType() || BT->isEnumeralType())
+  if (const VectorType *VT = CanonicalType->getAs<VectorType>()) {
+    int ArraySize = VT->getNumElements();
+
+    if (ArraySize > 4)
       return false;
 
-    // Check if it is an array type.
-    if (FirstQT->isArrayType())
+    QualType ElTy = VT->getElementType();
+    int TotalSizeInBytes = (SemaRef.Context.getTypeSize(ElTy) / 8) * ArraySize;
+
+    if (TotalSizeInBytes > 16)
----------------
bob80905 wrote:

With a division by 8, yes that is a good simplification

https://github.com/llvm/llvm-project/pull/115045