[HLSL] avoid unnamed bit fields when dealing with InitLists in HLSL (#159212)

In HLSL Init List code avoid initializing unnamed bitfields and avoid
initializing using unnamed bit fields.
Add tests.
Closes #157922

Author: spall

clang/lib/Sema/SemaHLSL.cpp

@@ -3323,7 +3323,8 @@ static void BuildFlattenedTypeList(QualType BaseTy,
 
       llvm::SmallVector<QualType, 16> FieldTypes;
       for (const auto *FD : RD->fields())
-        FieldTypes.push_back(FD->getType());
+        if (!FD->isUnnamedBitField())
+          FieldTypes.push_back(FD->getType());
       // Reverse the newly added sub-range.
       std::reverse(FieldTypes.begin(), FieldTypes.end());
       llvm::append_range(WorkList, FieldTypes);
@@ -4158,6 +4159,8 @@ class InitListTransformer {
       while (!RecordDecls.empty()) {
         CXXRecordDecl *RD = RecordDecls.pop_back_val();
         for (auto *FD : RD->fields()) {
+          if (FD->isUnnamedBitField())
+            continue;
           DeclAccessPair Found = DeclAccessPair::make(FD, FD->getAccess());
           DeclarationNameInfo NameInfo(FD->getDeclName(), E->getBeginLoc());
           ExprResult Res = S.BuildFieldReferenceExpr(
@@ -4207,7 +4210,8 @@ class InitListTransformer {
       while (!RecordDecls.empty()) {
         CXXRecordDecl *RD = RecordDecls.pop_back_val();
         for (auto *FD : RD->fields())
-          Inits.push_back(generateInitListsImpl(FD->getType()));
+          if (!FD->isUnnamedBitField())
+            Inits.push_back(generateInitListsImpl(FD->getType()));
       }
     }
     auto *NewInit = new (Ctx) InitListExpr(Ctx, Inits.front()->getBeginLoc(),

clang/test/CodeGenHLSL/BasicFeatures/InitLists.hlsl

@@ -45,6 +45,11 @@ struct SlicyBits {
   int W : 8;
 };
 
+struct Unnamed {
+  int A;
+  int : 8;
+};
+
 // Case 1: Extraneous braces get ignored in literal instantiation.
 // CHECK-LABEL: define hidden void @_Z5case1v(
 // CHECK-SAME: ptr dead_on_unwind noalias writable sret([[STRUCT_TWOFLOATS:%.*]]) align 1 [[AGG_RESULT:%.*]]) #[[ATTR0:[0-9]+]] {
@@ -959,3 +964,24 @@ int case17Helper(int x) {
 void case17() {
   int2 X = {case17Helper(0), case17Helper(1)};
 }
+
+// InitList with Struct with unnamed bitfield on LHS
+// CHECK-LABEL: case18
+// CHECK: [[U:%.*]] = alloca %struct.Unnamed, align 1
+// CHECK-NEXT: call void @llvm.memcpy.p0.p0.i32(ptr align 1 [[U]], ptr align 1 {{.*}}, i32 5, i1 false)
+void case18() {
+  Unnamed U = {1};
+}
+
+// InitList with Struct with unnamed bitfield on RHS
+// CHECK-LABEL: case19
+// CHECK: [[TI:%.*]] = alloca %struct.TwoInts, align 1
+// CHECK-NEXT: [[Z:%.*]] = getelementptr inbounds nuw %struct.TwoInts, ptr [[TI]], i32 0, i32 0
+// CHECK-NEXT: [[A:%.*]] = getelementptr inbounds nuw %struct.Unnamed, ptr %U, i32 0, i32 0
+// CHECK-NEXT: [[L:%.*]] = load i32, ptr [[A]], align 1
+// CHECK-NEXT: store i32 [[L]], ptr [[Z]], align 1
+// CHECK-NEXT: [[W:%.*]] = getelementptr inbounds nuw %struct.TwoInts, ptr [[TI]], i32 0, i32 1
+// CHECK-NEXT: store i32 1, ptr [[W]], align 1
+void case19(Unnamed U) {
+  TwoInts TI = {U, 1};
+}