1 files changed, 16 insertions, 3 deletions

diff --git a/clang/lib/CodeGen/CodeGenTBAA.h b/clang/lib/CodeGen/CodeGenTBAA.h
index a5b1f66bcd1..7b3473fe63f 100644
--- a/clang/lib/CodeGen/CodeGenTBAA.h
+++ b/clang/lib/CodeGen/CodeGenTBAA.h
@@ -34,9 +34,10 @@ class CGRecordLayout;
 
 // TBAAAccessKind - A kind of TBAA memory access descriptor.
 enum class TBAAAccessKind : unsigned {
-  Ordinary,
-  MayAlias,
-  Incomplete,
+  Ordinary,     // An ordinary memory access.
+  MayAlias,     // An access that may alias with any other accesses.
+  Incomplete,   // Used to designate pointee values of incomplete types.
+  UnionMember,  // An access to a direct or indirect union member.
 };
 
 // TBAAAccessInfo - Describes a memory access in terms of TBAA.
@@ -77,6 +78,14 @@ struct TBAAAccessInfo {
 
   bool isIncomplete() const { return Kind == TBAAAccessKind::Incomplete; }
 
+  static TBAAAccessInfo getUnionMemberInfo(llvm::MDNode *BaseType,
+                                           uint64_t Offset, uint64_t Size) {
+    return TBAAAccessInfo(TBAAAccessKind::UnionMember, BaseType,
+                          /* AccessType= */ nullptr, Offset, Size);
+  }
+
+  bool isUnionMember() const { return Kind == TBAAAccessKind::UnionMember; }
+
   bool operator==(const TBAAAccessInfo &Other) const {
     return Kind == Other.Kind &&
            BaseType == Other.BaseType &&
@@ -148,6 +157,10 @@ class CodeGenTBAA {
   /// considered to be equivalent to it.
   llvm::MDNode *getChar();
 
+  /// getUnionMemberType - Get metadata that represents the type of union
+  /// members.
+  llvm::MDNode *getUnionMemberType(uint64_t Size);
+
   /// CollectFields - Collect information about the fields of a type for
   /// !tbaa.struct metadata formation. Return false for an unsupported type.
   bool CollectFields(uint64_t BaseOffset,