Index: include/clang/AST/ASTContext.h
===================================================================
--- include/clang/AST/ASTContext.h	(revision 91861)
+++ include/clang/AST/ASTContext.h	(working copy)
@@ -400,6 +400,11 @@
   /// BlockPointer.
   QualType getNoReturnType(QualType T, bool AddNoReturn = true);
 
+  /// getCallConvType - Adds the specified calling convention attribute to
+  /// the given type, which must be a FunctionType or a pointer to an
+  /// allowable type.
+  QualType getCallConvType(QualType T, CallingConv CallConv);
+
   /// getComplexType - Return the uniqued reference to the type for a complex
   /// number with the specified element type.
   QualType getComplexType(QualType T);
@@ -516,7 +521,8 @@
 
   /// getFunctionNoProtoType - Return a K&R style C function type like 'int()'.
   ///
-  QualType getFunctionNoProtoType(QualType ResultTy, bool NoReturn = false);
+  QualType getFunctionNoProtoType(QualType ResultTy, bool NoReturn = false,
+                                  CallingConv CallConv = CC_Default);
 
   /// getFunctionType - Return a normal function type with a typed argument
   /// list.  isVariadic indicates whether the argument list includes '...'.
@@ -525,7 +531,8 @@
                            unsigned TypeQuals, bool hasExceptionSpec = false,
                            bool hasAnyExceptionSpec = false,
                            unsigned NumExs = 0, const QualType *ExArray = 0,
-                           bool NoReturn = false);
+                           bool NoReturn = false,
+                           CallingConv CallConv = CC_Default);
 
   /// getTypeDeclType - Return the unique reference to the type for
   /// the specified type declaration.
Index: include/clang/AST/Type.h
===================================================================
--- include/clang/AST/Type.h	(revision 91861)
+++ include/clang/AST/Type.h	(working copy)
@@ -385,7 +385,15 @@
   }
 };
 
+/// CallingConv - Specifies the calling convention that a function uses.
+enum CallingConv {
+  CC_Default,
+  CC_C,           // __attribute__((cdecl))
+  CC_X86StdCall,  // __attribute__((stdcall))
+  CC_X86FastCall  // __attribute__((fastcall))
+};
 
+
 /// QualType - For efficiency, we don't store CV-qualified types as nodes on
 /// their own: instead each reference to a type stores the qualifiers.  This
 /// greatly reduces the number of nodes we need to allocate for types (for
@@ -664,6 +672,10 @@
   /// false otherwise.
   bool getNoReturnAttr() const;
 
+  /// getCallConv - Returns the calling convention of the type if the type
+  /// is a function type, CC_Default otherwise.
+  CallingConv getCallConv() const;
+
 private:
   // These methods are implemented in a separate translation unit;
   // "static"-ize them to avoid creating temporary QualTypes in the
@@ -1708,21 +1720,25 @@
   /// NoReturn - Indicates if the function type is attribute noreturn.
   unsigned NoReturn : 1;
 
+  /// CallConv - The calling convention used by the function.
+  CallingConv CallConv : 2;
+
   // The type returned by the function.
   QualType ResultType;
 protected:
   FunctionType(TypeClass tc, QualType res, bool SubclassInfo,
                unsigned typeQuals, QualType Canonical, bool Dependent,
-               bool noReturn = false)
+               bool noReturn = false, CallingConv callConv = CC_Default)
     : Type(tc, Canonical, Dependent),
       SubClassData(SubclassInfo), TypeQuals(typeQuals), NoReturn(noReturn),
-      ResultType(res) {}
+      CallConv(callConv), ResultType(res) {}
   bool getSubClassData() const { return SubClassData; }
   unsigned getTypeQuals() const { return TypeQuals; }
 public:
 
   QualType getResultType() const { return ResultType; }
   bool getNoReturnAttr() const { return NoReturn; }
+  CallingConv getCallConv() const { return CallConv; }
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == FunctionNoProto ||
@@ -1735,9 +1751,9 @@
 /// no information available about its arguments.
 class FunctionNoProtoType : public FunctionType, public llvm::FoldingSetNode {
   FunctionNoProtoType(QualType Result, QualType Canonical,
-                      bool NoReturn = false)
+                      bool NoReturn = false, CallingConv CallConv = CC_Default)
     : FunctionType(FunctionNoProto, Result, false, 0, Canonical,
-                   /*Dependent=*/false, NoReturn) {}
+                   /*Dependent=*/false, NoReturn, CallConv) {}
   friend class ASTContext;  // ASTContext creates these.
 public:
   // No additional state past what FunctionType provides.
@@ -1779,10 +1795,12 @@
   FunctionProtoType(QualType Result, const QualType *ArgArray, unsigned numArgs,
                     bool isVariadic, unsigned typeQuals, bool hasExs,
                     bool hasAnyExs, const QualType *ExArray,
-                    unsigned numExs, QualType Canonical, bool NoReturn)
+                    unsigned numExs, QualType Canonical, bool NoReturn,
+                    CallingConv CallConv)
     : FunctionType(FunctionProto, Result, isVariadic, typeQuals, Canonical,
                    (Result->isDependentType() ||
-                    hasAnyDependentType(ArgArray, numArgs)), NoReturn),
+                    hasAnyDependentType(ArgArray, numArgs)), NoReturn,
+                   CallConv),
       NumArgs(numArgs), NumExceptions(numExs), HasExceptionSpec(hasExs),
       AnyExceptionSpec(hasAnyExs) {
     // Fill in the trailing argument array.
@@ -2801,6 +2819,21 @@
   return false;
 }
 
+/// getCallConv - Returns the calling convention of the type if the type
+/// is a function type, CC_Default otherwise.
+inline CallingConv QualType::getCallConv() const {
+  if (const PointerType *PT = getTypePtr()->getAs<PointerType>())
+    return PT->getPointeeType().getCallConv();
+  else if (const BlockPointerType *BPT =
+           getTypePtr()->getAs<BlockPointerType>()) {
+    if (const FunctionType *FT = BPT->getPointeeType()->getAs<FunctionType>())
+      return FT->getCallConv();
+  } else if (const FunctionType *FT = getTypePtr()->getAs<FunctionType>())
+    return FT->getCallConv();
+
+  return CC_Default;
+}
+
 /// isMoreQualifiedThan - Determine whether this type is more
 /// qualified than the Other type. For example, "const volatile int"
 /// is more qualified than "const int", "volatile int", and
Index: lib/Sema/SemaTemplateInstantiateDecl.cpp
===================================================================
--- lib/Sema/SemaTemplateInstantiateDecl.cpp	(revision 91861)
+++ lib/Sema/SemaTemplateInstantiateDecl.cpp	(working copy)
@@ -1529,7 +1529,8 @@
                                                  Proto->hasAnyExceptionSpec(),
                                                  Exceptions.size(),
                                                  Exceptions.data(),
-                                                 Proto->getNoReturnAttr()));
+                                                 Proto->getNoReturnAttr(),
+                                                 Proto->getCallConv()));
   }
 
   return false;
Index: lib/AST/ASTContext.cpp
===================================================================
--- lib/AST/ASTContext.cpp	(revision 91861)
+++ lib/AST/ASTContext.cpp	(working copy)
@@ -1200,45 +1200,60 @@
   return getExtQualType(TypeNode, Quals);
 }
 
-QualType ASTContext::getNoReturnType(QualType T, bool AddNoReturn) {
+static QualType getNoReturnCallConvType(ASTContext& Context, QualType T,
+                                        bool AddNoReturn,
+                                        CallingConv CallConv) {
   QualType ResultType;
   if (const PointerType *Pointer = T->getAs<PointerType>()) {
     QualType Pointee = Pointer->getPointeeType();
-    ResultType = getNoReturnType(Pointee, AddNoReturn);
+    ResultType = getNoReturnCallConvType(Context, Pointee, AddNoReturn,
+                                         CallConv);
     if (ResultType == Pointee)
       return T;
-    
-    ResultType = getPointerType(ResultType);
+
+    ResultType = Context.getPointerType(ResultType);
   } else if (const BlockPointerType *BlockPointer
                                               = T->getAs<BlockPointerType>()) {
     QualType Pointee = BlockPointer->getPointeeType();
-    ResultType = getNoReturnType(Pointee, AddNoReturn);
+    ResultType = getNoReturnCallConvType(Context, Pointee, AddNoReturn,
+                                         CallConv);
     if (ResultType == Pointee)
       return T;
-    
-    ResultType = getBlockPointerType(ResultType);
-  } else if (const FunctionType *F = T->getAs<FunctionType>()) {
-    if (F->getNoReturnAttr() == AddNoReturn)
+
+    ResultType = Context.getBlockPointerType(ResultType);
+   } else if (const FunctionType *F = T->getAs<FunctionType>()) {
+    if (F->getNoReturnAttr() == AddNoReturn && F->getCallConv() == CallConv)
       return T;
-    
+
     if (const FunctionNoProtoType *FNPT = dyn_cast<FunctionNoProtoType>(F)) {
-      ResultType = getFunctionNoProtoType(FNPT->getResultType(), AddNoReturn);
+      ResultType = Context.getFunctionNoProtoType(FNPT->getResultType(),
+                                                  AddNoReturn, CallConv);
     } else {
       const FunctionProtoType *FPT = cast<FunctionProtoType>(F);
       ResultType
-        = getFunctionType(FPT->getResultType(), FPT->arg_type_begin(),
-                          FPT->getNumArgs(), FPT->isVariadic(), 
-                          FPT->getTypeQuals(),
-                          FPT->hasExceptionSpec(), FPT->hasAnyExceptionSpec(),
-                          FPT->getNumExceptions(), FPT->exception_begin(), 
-                          AddNoReturn);
+        = Context.getFunctionType(FPT->getResultType(), FPT->arg_type_begin(),
+                                  FPT->getNumArgs(), FPT->isVariadic(),
+                                  FPT->getTypeQuals(),
+                                  FPT->hasExceptionSpec(),
+                                  FPT->hasAnyExceptionSpec(),
+                                  FPT->getNumExceptions(),
+                                  FPT->exception_begin(),
+                                  AddNoReturn, CallConv);
     }
   } else
     return T;
-  
-  return getQualifiedType(ResultType, T.getLocalQualifiers());
+
+  return Context.getQualifiedType(ResultType, T.getLocalQualifiers());
 }
 
+QualType ASTContext::getNoReturnType(QualType T, bool AddNoReturn) {
+  return getNoReturnCallConvType(*this, T, AddNoReturn, T.getCallConv());
+}
+
+QualType ASTContext::getCallConvType(QualType T, CallingConv CallConv) {
+  return getNoReturnCallConvType(*this, T, T.getNoReturnAttr(), CallConv);
+}
+
 /// getComplexType - Return the uniqued reference to the type for a complex
 /// number with the specified element type.
 QualType ASTContext::getComplexType(QualType T) {
@@ -1690,7 +1705,8 @@
 
 /// getFunctionNoProtoType - Return a K&R style C function type like 'int()'.
 ///
-QualType ASTContext::getFunctionNoProtoType(QualType ResultTy, bool NoReturn) {
+QualType ASTContext::getFunctionNoProtoType(QualType ResultTy, bool NoReturn,
+                                            CallingConv CallConv) {
   // Unique functions, to guarantee there is only one function of a particular
   // structure.
   llvm::FoldingSetNodeID ID;
@@ -1703,7 +1719,8 @@
 
   QualType Canonical;
   if (!ResultTy.isCanonical()) {
-    Canonical = getFunctionNoProtoType(getCanonicalType(ResultTy), NoReturn);
+    Canonical = getFunctionNoProtoType(getCanonicalType(ResultTy), NoReturn,
+                                       CallConv);
 
     // Get the new insert position for the node we care about.
     FunctionNoProtoType *NewIP =
@@ -1724,7 +1741,8 @@
                                      unsigned NumArgs, bool isVariadic,
                                      unsigned TypeQuals, bool hasExceptionSpec,
                                      bool hasAnyExceptionSpec, unsigned NumExs,
-                                     const QualType *ExArray, bool NoReturn) {
+                                     const QualType *ExArray, bool NoReturn,
+                                     CallingConv CallConv) {
   // Unique functions, to guarantee there is only one function of a particular
   // structure.
   llvm::FoldingSetNodeID ID;
@@ -1755,7 +1773,7 @@
     Canonical = getFunctionType(getCanonicalType(ResultTy),
                                 CanonicalArgs.data(), NumArgs,
                                 isVariadic, TypeQuals, false,
-                                false, 0, 0, NoReturn);
+                                false, 0, 0, NoReturn, CallConv);
 
     // Get the new insert position for the node we care about.
     FunctionProtoType *NewIP =
@@ -1772,7 +1790,7 @@
                                  NumExs*sizeof(QualType), TypeAlignment);
   new (FTP) FunctionProtoType(ResultTy, ArgArray, NumArgs, isVariadic,
                               TypeQuals, hasExceptionSpec, hasAnyExceptionSpec,
-                              ExArray, NumExs, Canonical, NoReturn);
+                              ExArray, NumExs, Canonical, NoReturn, CallConv);
   Types.push_back(FTP);
   FunctionProtoTypes.InsertNode(FTP, InsertPos);
   return QualType(FTP, 0);
@@ -4213,6 +4231,11 @@
     allLTypes = false;
   if (NoReturn != rbase->getNoReturnAttr())
     allRTypes = false;
+  CallingConv lcc = lbase->getCallConv();
+  CallingConv rcc = rbase->getCallConv();
+  // Compatible functions must have the same calling convention
+  if((lcc == 0 || rcc != 0) && lcc != rcc)
+    return QualType();
 
   if (lproto && rproto) { // two C99 style function prototypes
     assert(!lproto->hasExceptionSpec() && !rproto->hasExceptionSpec() &&
@@ -4248,7 +4271,7 @@
     if (allRTypes) return rhs;
     return getFunctionType(retType, types.begin(), types.size(),
                            lproto->isVariadic(), lproto->getTypeQuals(),
-                           NoReturn);
+                           NoReturn, lcc);
   }
 
   if (lproto) allRTypes = false;
@@ -4275,12 +4298,12 @@
     if (allRTypes) return rhs;
     return getFunctionType(retType, proto->arg_type_begin(),
                            proto->getNumArgs(), proto->isVariadic(),
-                           proto->getTypeQuals(), NoReturn);
+                           proto->getTypeQuals(), NoReturn, lcc);
   }
 
   if (allLTypes) return lhs;
   if (allRTypes) return rhs;
-  return getFunctionNoProtoType(retType, NoReturn);
+  return getFunctionNoProtoType(retType, NoReturn, lcc);
 }
 
 QualType ASTContext::mergeTypes(QualType LHS, QualType RHS) {
