Support for C1x _Atomic specifier (see testcase). This is primarily being committed at the moment to help support C++0x <atomic>, but it should be a solid base for implementing the full specification of C1x _Atomic.

Thanks to Jeffrey Yasskin for the thorough review!



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@141330 91177308-0d34-0410-b5e6-96231b3b80d8

39 files changed, 483 insertions, 9 deletions

diff --git a/include/clang/AST/ASTContext.h b/include/clang/AST/ASTContext.h
index a18a45eb40..09defdb31e 100644
--- a/include/clang/AST/ASTContext.h
+++ b/include/clang/AST/ASTContext.h
@@ -120,6 +120,7 @@ class ASTContext : public llvm::RefCountedBase<ASTContext> {
   mutable llvm::FoldingSet<ObjCObjectTypeImpl> ObjCObjectTypes;
   mutable llvm::FoldingSet<ObjCObjectPointerType> ObjCObjectPointerTypes;
   mutable llvm::FoldingSet<AutoType> AutoTypes;
+  mutable llvm::FoldingSet<AtomicType> AtomicTypes;
   llvm::FoldingSet<AttributedType> AttributedTypes;
 
   mutable llvm::FoldingSet<QualifiedTemplateName> QualifiedTemplateNames;
@@ -601,6 +602,10 @@ public:
     return CanQualType::CreateUnsafe(getPointerType((QualType) T));
   }
 
+  /// getAtomicType - Return the uniqued reference to the atomic type for
+  /// the specified type.
+  QualType getAtomicType(QualType T) const;
+
   /// getBlockPointerType - Return the uniqued reference to the type for a block
   /// of the specified type.
   QualType getBlockPointerType(QualType T) const;
diff --git a/include/clang/AST/RecursiveASTVisitor.h b/include/clang/AST/RecursiveASTVisitor.h
index 36add6c457..a224bb0a40 100644
--- a/include/clang/AST/RecursiveASTVisitor.h
+++ b/include/clang/AST/RecursiveASTVisitor.h
@@ -813,6 +813,10 @@ DEF_TRAVERSE_TYPE(ObjCObjectPointerType, {
     TRY_TO(TraverseType(T->getPointeeType()));
   })
 
+DEF_TRAVERSE_TYPE(AtomicType, {
+    TRY_TO(TraverseType(T->getValueType()));
+  })
+
 #undef DEF_TRAVERSE_TYPE
 
 // ----------------- TypeLoc traversal -----------------
@@ -1041,6 +1045,10 @@ DEF_TRAVERSE_TYPELOC(ObjCObjectPointerType, {
     TRY_TO(TraverseTypeLoc(TL.getPointeeLoc()));
   })
 
+DEF_TRAVERSE_TYPELOC(AtomicType, {
+    TRY_TO(TraverseTypeLoc(TL.getValueLoc()));
+  })
+
 #undef DEF_TRAVERSE_TYPELOC
 
 // ----------------- Decl traversal -----------------
diff --git a/include/clang/AST/Type.h b/include/clang/AST/Type.h
index 0b4c8f715d..4a44710938 100644
--- a/include/clang/AST/Type.h
+++ b/include/clang/AST/Type.h
@@ -1449,6 +1449,7 @@ public:
   bool isCARCBridgableType() const;
   bool isTemplateTypeParmType() const;          // C++ template type parameter
   bool isNullPtrType() const;                   // C++0x nullptr_t
+  bool isAtomicType() const;                    // C1X _Atomic()
 
   /// Determines if this type, which must satisfy
   /// isObjCLifetimeType(), is implicitly __unsafe_unretained rather
@@ -4352,6 +4353,37 @@ public:
   static bool classof(const ObjCObjectPointerType *) { return true; }
 };
 
+class AtomicType : public Type, public llvm::FoldingSetNode {
+  QualType ValueType;
+
+  AtomicType(QualType ValTy, QualType Canonical)
+    : Type(Atomic, Canonical, ValTy->isDependentType(),
+           ValTy->isInstantiationDependentType(),
+           ValTy->isVariablyModifiedType(),
+           ValTy->containsUnexpandedParameterPack()),
+      ValueType(ValTy) {}
+  friend class ASTContext;  // ASTContext creates these.
+
+  public:
+  /// getValueType - Gets the type contained by this atomic type, i.e.
+  /// the type returned by performing an atomic load of this atomic type.
+  QualType getValueType() const { return ValueType; }
+
+  bool isSugared() const { return false; }
+  QualType desugar() const { return QualType(this, 0); }
+
+  void Profile(llvm::FoldingSetNodeID &ID) {
+    Profile(ID, getValueType());
+  }
+  static void Profile(llvm::FoldingSetNodeID &ID, QualType T) {
+    ID.AddPointer(T.getAsOpaquePtr());
+  }
+  static bool classof(const Type *T) {
+    return T->getTypeClass() == Atomic;
+  }
+  static bool classof(const AtomicType *) { return true; }
+};
+
 /// A qualifier set is used to build a set of qualifiers.
 class QualifierCollector : public Qualifiers {
 public:
@@ -4677,6 +4709,9 @@ inline bool Type::isObjCObjectOrInterfaceType() const {
   return isa<ObjCInterfaceType>(CanonicalType) || 
     isa<ObjCObjectType>(CanonicalType);
 }
+inline bool Type::isAtomicType() const {
+  return isa<AtomicType>(CanonicalType);
+}
 
 inline bool Type::isObjCQualifiedIdType() const {
   if (const ObjCObjectPointerType *OPT = getAs<ObjCObjectPointerType>())
diff --git a/include/clang/AST/TypeLoc.h b/include/clang/AST/TypeLoc.h
index 8e3e8d37c8..02ced65e5c 100644
--- a/include/clang/AST/TypeLoc.h
+++ b/include/clang/AST/TypeLoc.h
@@ -1730,6 +1730,62 @@ public:
   }
 };
 
+struct AtomicTypeLocInfo {
+  SourceLocation KWLoc, LParenLoc, RParenLoc;
+};
+
+class AtomicTypeLoc : public ConcreteTypeLoc<UnqualTypeLoc, AtomicTypeLoc,
+                                             AtomicType, AtomicTypeLocInfo> {
+public:  
+  TypeLoc getValueLoc() const {
+    return this->getInnerTypeLoc();
+  }
+
+  SourceRange getLocalSourceRange() const {
+    return SourceRange(getKWLoc(), getRParenLoc());
+  }
+
+  SourceLocation getKWLoc() const {
+    return this->getLocalData()->KWLoc;
+  }
+  void setKWLoc(SourceLocation Loc) {
+    this->getLocalData()->KWLoc = Loc;
+  }
+
+  SourceLocation getLParenLoc() const {
+    return this->getLocalData()->LParenLoc;
+  }
+  void setLParenLoc(SourceLocation Loc) {
+    this->getLocalData()->LParenLoc = Loc;
+  }
+
+  SourceLocation getRParenLoc() const {
+    return this->getLocalData()->RParenLoc;
+  }
+  void setRParenLoc(SourceLocation Loc) {
+    this->getLocalData()->RParenLoc = Loc;
+  }
+
+  SourceRange getParensRange() const {
+    return SourceRange(getLParenLoc(), getRParenLoc());
+  }
+  void setParensRange(SourceRange Range) {
+    setLParenLoc(Range.getBegin());
+    setRParenLoc(Range.getEnd());
+  }
+
+  void initializeLocal(ASTContext &Context, SourceLocation Loc) {
+    setKWLoc(Loc);
+    setLParenLoc(Loc);
+    setRParenLoc(Loc);
+  }
+
+  QualType getInnerType() const {
+    return this->getTypePtr()->getValueType();
+  }
+};
+
+
 }
 
 #endif
diff --git a/include/clang/AST/TypeNodes.def b/include/clang/AST/TypeNodes.def
index 0792d0d9b3..d5c485f8a3 100644
--- a/include/clang/AST/TypeNodes.def
+++ b/include/clang/AST/TypeNodes.def
@@ -102,9 +102,10 @@ DEPENDENT_TYPE(PackExpansion, Type)
 TYPE(ObjCObject, Type)
 TYPE(ObjCInterface, ObjCObjectType)
 TYPE(ObjCObjectPointer, Type)
+TYPE(Atomic, Type)
 
 #ifdef LAST_TYPE
-LAST_TYPE(ObjCObjectPointer)
+LAST_TYPE(Atomic)
 #undef LAST_TYPE
 #endif
 
diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index d4c118b447..411d49c912 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3073,6 +3073,10 @@ def err_block_with_return_type_requires_args : Error<
   "block with explicit return type requires argument list">;
 def err_func_def_incomplete_result : Error<
   "incomplete result type %0 in function definition">;
+def err_atomic_specifier_bad_type : Error<
+  "_Atomic cannot be applied to "
+  "%select{incomplete |array |function |reference |atomic |qualified |}0type "
+  "%1 %select{||||||which is not trivially copyable}0">;
 
 // Expressions.
 def ext_sizeof_function_type : Extension<
diff --git a/include/clang/Basic/Specifiers.h b/include/clang/Basic/Specifiers.h
index be59ec5a56..1e89a8c817 100644
--- a/include/clang/Basic/Specifiers.h
+++ b/include/clang/Basic/Specifiers.h
@@ -57,6 +57,7 @@ namespace clang {
     TST_underlyingType, // __underlying_type for C++0x
     TST_auto,         // C++0x auto
     TST_unknown_anytype, // __unknown_anytype extension
+    TST_atomic,       // C1X _Atomic
     TST_error         // erroneous type
   };
   
diff --git a/include/clang/Basic/TokenKinds.def b/include/clang/Basic/TokenKinds.def
index 1256caabec..151a75d1e7 100644
--- a/include/clang/Basic/TokenKinds.def
+++ b/include/clang/Basic/TokenKinds.def
@@ -250,6 +250,7 @@ KEYWORD(void                        , KEYALL)
 KEYWORD(volatile                    , KEYALL)
 KEYWORD(while                       , KEYALL)
 KEYWORD(_Alignas                    , KEYALL)
+KEYWORD(_Atomic                     , KEYALL)
 KEYWORD(_Bool                       , KEYNOCXX)
 KEYWORD(_Complex                    , KEYALL)
 KEYWORD(_Generic                    , KEYALL)
diff --git a/include/clang/Parse/Parser.h b/include/clang/Parse/Parser.h
index e8494767b5..cf9bbbe9dd 100644
--- a/include/clang/Parse/Parser.h
+++ b/include/clang/Parse/Parser.h
@@ -1768,7 +1768,8 @@ private:
   void ParseTypeofSpecifier(DeclSpec &DS);
   void ParseDecltypeSpecifier(DeclSpec &DS);
   void ParseUnderlyingTypeSpecifier(DeclSpec &DS);
-  
+  void ParseAtomicSpecifier(DeclSpec &DS);
+
   ExprResult ParseAlignArgument(SourceLocation Start);
   void ParseAlignmentSpecifier(ParsedAttributes &Attrs,
                                SourceLocation *endLoc = 0);
diff --git a/include/clang/Sema/DeclSpec.h b/include/clang/Sema/DeclSpec.h
index 645ddcb468..3f11ee4f55 100644
--- a/include/clang/Sema/DeclSpec.h
+++ b/include/clang/Sema/DeclSpec.h
@@ -260,6 +260,7 @@ public:
   static const TST TST_underlyingType = clang::TST_underlyingType;
   static const TST TST_auto = clang::TST_auto;
   static const TST TST_unknown_anytype = clang::TST_unknown_anytype;
+  static const TST TST_atomic = clang::TST_atomic;
   static const TST TST_error = clang::TST_error;
 
   // type-qualifiers
@@ -356,7 +357,7 @@ private:
 
   static bool isTypeRep(TST T) {
     return (T == TST_typename || T == TST_typeofType ||
-            T == TST_underlyingType);
+            T == TST_underlyingType || T == TST_atomic);
   }
   static bool isExprRep(TST T) {
     return (T == TST_typeofExpr || T == TST_decltype);
diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index aad52fcab8..4b8bbdc6ea 100644
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -793,6 +793,7 @@ public:
   QualType BuildBlockPointerType(QualType T,
                                  SourceLocation Loc, DeclarationName Entity);
   QualType BuildParenType(QualType T);
+  QualType BuildAtomicType(QualType T, SourceLocation Loc);
 
   TypeSourceInfo *GetTypeForDeclarator(Declarator &D, Scope *S);
   TypeSourceInfo *GetTypeForDeclaratorCast(Declarator &D, QualType FromTy);
diff --git a/include/clang/Serialization/ASTBitCodes.h b/include/clang/Serialization/ASTBitCodes.h
index b8db49e76a..9a8eba2427 100644
--- a/include/clang/Serialization/ASTBitCodes.h
+++ b/include/clang/Serialization/ASTBitCodes.h
@@ -647,7 +647,9 @@ namespace clang {
       /// \brief A AutoType record.
       TYPE_AUTO                  = 38,
       /// \brief A UnaryTransformType record.
-      TYPE_UNARY_TRANSFORM       = 39
+      TYPE_UNARY_TRANSFORM       = 39,
+      /// \brief An AtomicType record.
+      TYPE_ATOMIC                = 40
     };
 
     /// \brief The type IDs for special types constructed by semantic
diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index 055ed7c08c..3377799e3d 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -1063,6 +1063,11 @@ ASTContext::getTypeInfo(const Type *T) const {
       return getTypeInfo(getCanonicalType(T));
   }
 
+  case Type::Atomic: {
+    // FIXME: The alignment needs to be "fixed".
+    return getTypeInfo(cast<AtomicType>(T)->getValueType());
+  }
+
   }
 
   assert(Align && (Align & (Align-1)) == 0 && "Alignment must be power of 2");
@@ -1707,6 +1712,12 @@ QualType ASTContext::getVariableArrayDecayedType(QualType type) const {
     break;
   }
 
+  case Type::Atomic: {
+    const AtomicType *at = cast<AtomicType>(ty);
+    result = getAtomicType(getVariableArrayDecayedType(at->getValueType()));
+    break;
+  }
+
   case Type::ConstantArray: {
     const ConstantArrayType *cat = cast<ConstantArrayType>(ty);
     result = getConstantArrayType(
@@ -2904,6 +2915,34 @@ QualType ASTContext::getAutoType(QualType DeducedType) const {
   return QualType(AT, 0);
 }
 
+/// getAtomicType - Return the uniqued reference to the atomic type for
+/// the given value type.
+QualType ASTContext::getAtomicType(QualType T) const {
+  // Unique pointers, to guarantee there is only one pointer of a particular
+  // structure.
+  llvm::FoldingSetNodeID ID;
+  AtomicType::Profile(ID, T);
+
+  void *InsertPos = 0;
+  if (AtomicType *AT = AtomicTypes.FindNodeOrInsertPos(ID, InsertPos))
+    return QualType(AT, 0);
+
+  // If the atomic value type isn't canonical, this won't be a canonical type
+  // either, so fill in the canonical type field.
+  QualType Canonical;
+  if (!T.isCanonical()) {
+    Canonical = getAtomicType(getCanonicalType(T));
+
+    // Get the new insert position for the node we care about.
+    AtomicType *NewIP = AtomicTypes.FindNodeOrInsertPos(ID, InsertPos);
+    assert(NewIP == 0 && "Shouldn't be in the map!"); (void)NewIP;
+  }
+  AtomicType *New = new (*this, TypeAlignment) AtomicType(T, Canonical);
+  Types.push_back(New);
+  AtomicTypes.InsertNode(New, InsertPos);
+  return QualType(New, 0);
+}
+
 /// getAutoDeductType - Get type pattern for deducing against 'auto'.
 QualType ASTContext::getAutoDeductType() const {
   if (AutoDeductTy.isNull())
@@ -5802,6 +5841,24 @@ QualType ASTContext::mergeTypes(QualType LHS, QualType RHS,
       return RHS;
     return getBlockPointerType(ResultType);
   }
+  case Type::Atomic:
+  {
+    // Merge two pointer types, while trying to preserve typedef info
+    QualType LHSValue = LHS->getAs<AtomicType>()->getValueType();
+    QualType RHSValue = RHS->getAs<AtomicType>()->getValueType();
+    if (Unqualified) {
+      LHSValue = LHSValue.getUnqualifiedType();
+      RHSValue = RHSValue.getUnqualifiedType();
+    }
+    QualType ResultType = mergeTypes(LHSValue, RHSValue, false, 
+                                     Unqualified);
+    if (ResultType.isNull()) return QualType();
+    if (getCanonicalType(LHSValue) == getCanonicalType(ResultType))
+      return LHS;
+    if (getCanonicalType(RHSValue) == getCanonicalType(ResultType))
+      return RHS;
+    return getAtomicType(ResultType);
+  }
   case Type::ConstantArray:
   {
     const ConstantArrayType* LCAT = getAsConstantArrayType(LHS);
diff --git a/lib/AST/ASTImporter.cpp b/lib/AST/ASTImporter.cpp
index e50dcbe4b0..e95d01a98f 100644
--- a/lib/AST/ASTImporter.cpp
+++ b/lib/AST/ASTImporter.cpp
@@ -810,7 +810,15 @@ static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
       return false;
     break;
   }
-      
+
+  case Type::Atomic: {
+    if (!IsStructurallyEquivalent(Context,
+                                  cast<AtomicType>(T1)->getValueType(),
+                                  cast<AtomicType>(T2)->getValueType()))
+      return false;
+    break;
+  }
+
   } // end switch
 
   return true;
diff --git a/lib/AST/ItaniumMangle.cpp b/lib/AST/ItaniumMangle.cpp
index e94cb2d54b..41cfa6ad01 100644
--- a/lib/AST/ItaniumMangle.cpp
+++ b/lib/AST/ItaniumMangle.cpp
@@ -788,6 +788,7 @@ void CXXNameMangler::mangleUnresolvedPrefix(NestedNameSpecifier *qualifier,
     case Type::ObjCObject:
     case Type::ObjCInterface:
     case Type::ObjCObjectPointer:
+    case Type::Atomic:
       llvm_unreachable("type is illegal as a nested name specifier");
 
     case Type::SubstTemplateTypeParmPack:
@@ -2111,6 +2112,13 @@ void CXXNameMangler::mangleType(const AutoType *T) {
     mangleType(D);
 }
 
+void CXXNameMangler::mangleType(const AtomicType *T) {
+  // <type> ::= U <source-name> <type>	# vendor extended type qualifier
+  // (Until there's a standardized mangling...)
+  Out << "U7_Atomic";
+  mangleType(T->getValueType());
+}
+
 void CXXNameMangler::mangleIntegerLiteral(QualType T,
                                           const llvm::APSInt &Value) {
   //  <expr-primary> ::= L <type> <value number> E # integer literal
diff --git a/lib/AST/MicrosoftMangle.cpp b/lib/AST/MicrosoftMangle.cpp
index a5bfd7d318..e327d8b180 100644
--- a/lib/AST/MicrosoftMangle.cpp
+++ b/lib/AST/MicrosoftMangle.cpp
@@ -1113,6 +1113,10 @@ void MicrosoftCXXNameMangler::mangleType(const AutoType *T) {
   llvm_unreachable("Don't know how to mangle AutoTypes yet!");
 }
 
+void MicrosoftCXXNameMangler::mangleType(const AtomicType *T) {
+  llvm_unreachable("Don't know how to mangle AtomicTypes yet!");
+}
+
 void MicrosoftMangleContext::mangleName(const NamedDecl *D,
                                         raw_ostream &Out) {
   assert((isa<FunctionDecl>(D) || isa<VarDecl>(D)) &&
diff --git a/lib/AST/Type.cpp b/lib/AST/Type.cpp
index a2c6954d75..60cb3fa33e 100644
--- a/lib/AST/Type.cpp
+++ b/lib/AST/Type.cpp
@@ -2113,6 +2113,8 @@ static CachedProperties computeCachedProperties(const Type *T) {
     return Cache::get(cast<ObjCObjectType>(T)->getBaseType());
   case Type::ObjCObjectPointer:
     return Cache::get(cast<ObjCObjectPointerType>(T)->getPointeeType());
+  case Type::Atomic:
+    return Cache::get(cast<AtomicType>(T)->getValueType());
   }
 
   llvm_unreachable("unhandled type class");
diff --git a/lib/AST/TypePrinter.cpp b/lib/AST/TypePrinter.cpp
index 855cc02d9e..fb7b918ca2 100644
--- a/lib/AST/TypePrinter.cpp
+++ b/lib/AST/TypePrinter.cpp
@@ -123,6 +123,7 @@ void TypePrinter::print(const Type *T, Qualifiers Quals, std::string &buffer) {
     case Type::DependentTemplateSpecialization:
     case Type::ObjCObject:
     case Type::ObjCInterface:
+    case Type::Atomic:
       CanPrefixQualifiers = true;
       break;
       
@@ -581,6 +582,16 @@ void TypePrinter::printAuto(const AutoType *T, std::string &S) {
   }
 }
 
+void TypePrinter::printAtomic(const AtomicType *T, std::string &S) {
+  if (!S.empty())
+    S = ' ' + S;
+  std::string Str;
+  IncludeStrongLifetimeRAII Strong(Policy);
+  print(T->getValueType(), Str);
+
+  S = "_Atomic(" + Str + ")" + S;
+}
+
 /// Appends the given scope to the end of a string.
 void TypePrinter::AppendScope(DeclContext *DC, std::string &Buffer) {
   if (DC->isTranslationUnit()) return;
diff --git a/lib/CodeGen/CGDebugInfo.cpp b/lib/CodeGen/CGDebugInfo.cpp
index 7bd6fc2fb0..eda73253b5 100644
--- a/lib/CodeGen/CGDebugInfo.cpp
+++ b/lib/CodeGen/CGDebugInfo.cpp
@@ -1423,6 +1423,13 @@ llvm::DIType CGDebugInfo::CreateType(const MemberPointerType *Ty,
                                    0, 0, Elements);
 }
 
+llvm::DIType CGDebugInfo::CreateType(const AtomicType *Ty, 
+                                     llvm::DIFile U) {
+  // Ignore the atomic wrapping
+  // FIXME: What is the correct representation?
+  return getOrCreateType(Ty->getValueType(), U);
+}
+
 /// CreateEnumType - get enumeration type.
 llvm::DIType CGDebugInfo::CreateEnumType(const EnumDecl *ED) {
   llvm::DIFile Unit = getOrCreateFile(ED->getLocation());
@@ -1581,6 +1588,9 @@ llvm::DIType CGDebugInfo::CreateTypeNode(QualType Ty,
   case Type::MemberPointer:
     return CreateType(cast<MemberPointerType>(Ty), Unit);
 
+  case Type::Atomic:
+    return CreateType(cast<AtomicType>(Ty), Unit);
+
   case Type::Attributed:
   case Type::TemplateSpecialization:
   case Type::Elaborated:
diff --git a/lib/CodeGen/CGDebugInfo.h b/lib/CodeGen/CGDebugInfo.h
index 19d1ff388c..68b3985961 100644
--- a/lib/CodeGen/CGDebugInfo.h
+++ b/lib/CodeGen/CGDebugInfo.h
@@ -96,6 +96,7 @@ class CGDebugInfo {
   llvm::DIType CreateType(const LValueReferenceType *Ty, llvm::DIFile F);
   llvm::DIType CreateType(const RValueReferenceType *Ty, llvm::DIFile Unit);
   llvm::DIType CreateType(const MemberPointerType *Ty, llvm::DIFile F);
+  llvm::DIType CreateType(const AtomicType *Ty, llvm::DIFile F);
   llvm::DIType CreateEnumType(const EnumDecl *ED);
   llvm::DIType getOrCreateMethodType(const CXXMethodDecl *Method,
                                      llvm::DIFile F);
diff --git a/lib/CodeGen/CGRTTI.cpp b/lib/CodeGen/CGRTTI.cpp
index a1105d2894..2ad1ed3930 100644
--- a/lib/CodeGen/CGRTTI.cpp
+++ b/lib/CodeGen/CGRTTI.cpp
@@ -404,6 +404,7 @@ void RTTIBuilder::BuildVTablePointer(const Type *Ty) {
   case Type::Vector:
   case Type::ExtVector:
   case Type::Complex:
+  case Type::Atomic:
   // FIXME: GCC treats block pointers as fundamental types?!
   case Type::BlockPointer:
     // abi::__fundamental_type_info.
@@ -656,6 +657,10 @@ llvm::Constant *RTTIBuilder::BuildTypeInfo(QualType Ty, bool Force) {
   case Type::MemberPointer:
     BuildPointerToMemberTypeInfo(cast<MemberPointerType>(Ty));
     break;
+
+  case Type::Atomic:
+    // No fields, at least for the moment.
+    break;
   }
 
   llvm::Constant *Init = llvm::ConstantStruct::getAnon(Fields);
diff --git a/lib/CodeGen/CodeGenFunction.cpp b/lib/CodeGen/CodeGenFunction.cpp
index 12def6728f..2c6e7b0acd 100644
--- a/lib/CodeGen/CodeGenFunction.cpp
+++ b/lib/CodeGen/CodeGenFunction.cpp
@@ -87,6 +87,10 @@ bool CodeGenFunction::hasAggregateLLVMType(QualType type) {
   case Type::ObjCObject:
   case Type::ObjCInterface:
     return true;
+
+  // In IRGen, atomic types are just the underlying type
+  case Type::Atomic:
+    return hasAggregateLLVMType(type->getAs<AtomicType>()->getValueType());
   }
   llvm_unreachable("unknown type kind!");
 }
@@ -983,6 +987,10 @@ void CodeGenFunction::EmitVariablyModifiedType(QualType type) {
     case Type::FunctionNoProto:
       type = cast<FunctionType>(ty)->getResultType();
       break;
+
+    case Type::Atomic:
+      type = cast<AtomicType>(ty)->getValueType();
+      break;
     }
   } while (type->isVariablyModifiedType());
 }
diff --git a/lib/CodeGen/CodeGenTypes.cpp b/lib/CodeGen/CodeGenTypes.cpp
index 3032f820c6..61c1581798 100644
--- a/lib/CodeGen/CodeGenTypes.cpp
+++ b/lib/CodeGen/CodeGenTypes.cpp
@@ -548,6 +548,11 @@ llvm::Type *CodeGenTypes::ConvertType(QualType T) {
       getCXXABI().ConvertMemberPointerType(cast<MemberPointerType>(Ty));
     break;
   }
+
+  case Type::Atomic: {
+    ResultType = ConvertTypeForMem(cast<AtomicType>(Ty)->getValueType());
+    break;
+  }
   }
   
   assert(ResultType && "Didn't convert a type?");
diff --git a/lib/Parse/ParseDecl.cpp b/lib/Parse/ParseDecl.cpp
index 5e1a42dc07..82155e44fd 100644
--- a/lib/Parse/ParseDecl.cpp
+++ b/lib/Parse/ParseDecl.cpp
@@ -2184,6 +2184,11 @@ void Parser::ParseDeclarationSpecifiers(DeclSpec &DS,
 
     case tok::kw___underlying_type:
       ParseUnderlyingTypeSpecifier(DS);
+      continue;
+
+    case tok::kw__Atomic:
+      ParseAtomicSpecifier(DS);
+      continue;
 
     // OpenCL qualifiers:
     case tok::kw_private: 
@@ -2460,6 +2465,10 @@ bool Parser::ParseOptionalTypeSpecifier(DeclSpec &DS, bool& isInvalid,
     ParseUnderlyingTypeSpecifier(DS);
     return true;
 
+  case tok::kw__Atomic:
+    ParseAtomicSpecifier(DS);
+    return true;
+
   // OpenCL qualifiers:
   case tok::kw_private: 
     if (!getLang().OpenCL)
@@ -3219,6 +3228,10 @@ bool Parser::isTypeSpecifierQualifier() {
 
   case tok::kw_private:
     return getLang().OpenCL;
+
+  // C1x _Atomic()
+  case tok::kw__Atomic:
+    return true;
   }
 }
 
@@ -3338,6 +3351,10 @@ bool Parser::isDeclarationSpecifier(bool DisambiguatingWithExpression) {
   case tok::kw_decltype:
     return true;
 
+    // C1x _Atomic()
+  case tok::kw__Atomic:
+    return true;
+
     // GNU ObjC bizarre protocol extension: <proto1,proto2> with implicit 'id'.
   case tok::less:
     return getLang().ObjC1;
@@ -4504,6 +4521,47 @@ void Parser::ParseTypeofSpecifier(DeclSpec &DS) {
     Diag(StartLoc, DiagID) << PrevSpec;
 }
 
+/// [C1X]   atomic-specifier:
+///           _Atomic ( type-name )
+///
+void Parser::ParseAtomicSpecifier(DeclSpec &DS) {
+  assert(Tok.is(tok::kw__Atomic) && "Not an atomic specifier");
+
+  SourceLocation StartLoc = ConsumeToken();
+  SourceLocation LParenLoc = Tok.getLocation();
+
+  if (ExpectAndConsume(tok::l_paren, diag::err_expected_lparen_after,
+                       "_Atomic")) {
+    SkipUntil(tok::r_paren);
+    return;