lib/AST/MicrosoftMangle.cpp

//===--- MicrosoftMangle.cpp - Microsoft Visual C++ Name Mangling ---------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This provides C++ name mangling targetting the Microsoft Visual C++ ABI.
//
//===----------------------------------------------------------------------===//

#include "clang/AST/Mangle.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/ExprCXX.h"
#include "clang/Basic/ABI.h"

using namespace clang;

namespace {

/// MicrosoftCXXNameMangler - Manage the mangling of a single name for the
/// Microsoft Visual C++ ABI.
class MicrosoftCXXNameMangler {
  MangleContext &Context;
  llvm::raw_svector_ostream &Out;

  ASTContext &getASTContext() const { return Context.getASTContext(); }

public:
  MicrosoftCXXNameMangler(MangleContext &C, llvm::raw_svector_ostream &Out_)
  : Context(C), Out(Out_) { }

  void mangle(const NamedDecl *D, llvm::StringRef Prefix = "?");
  void mangleName(const NamedDecl *ND);
  void mangleFunctionEncoding(const FunctionDecl *FD);
  void mangleVariableEncoding(const VarDecl *VD);
  void mangleNumber(int64_t Number);
  void mangleType(QualType T);

private:
  void mangleUnqualifiedName(const NamedDecl *ND) {
    mangleUnqualifiedName(ND, ND->getDeclName());
  }
  void mangleUnqualifiedName(const NamedDecl *ND, DeclarationName Name);
  void mangleSourceName(const IdentifierInfo *II);
  void manglePostfix(const DeclContext *DC, bool NoFunction=false);
  void mangleOperatorName(OverloadedOperatorKind OO);
  void mangleQualifiers(Qualifiers Quals, bool IsMember);

  void mangleObjCMethodName(const ObjCMethodDecl *MD);

  // Declare manglers for every type class.
#define ABSTRACT_TYPE(CLASS, PARENT)
#define NON_CANONICAL_TYPE(CLASS, PARENT)
#define TYPE(CLASS, PARENT) void mangleType(const CLASS##Type *T);
#include "clang/AST/TypeNodes.def"
  
  void mangleType(const TagType*);
  void mangleType(const FunctionType *T, const FunctionDecl *D,
                  bool IsStructor, bool IsInstMethod);
  void mangleType(const ArrayType *T, bool IsGlobal);
  void mangleExtraDimensions(QualType T);
  void mangleFunctionClass(const FunctionDecl *FD);
  void mangleCallingConvention(const FunctionType *T, bool IsInstMethod = false);
  void mangleThrowSpecification(const FunctionProtoType *T);

};

/// MicrosoftMangleContext - Overrides the default MangleContext for the
/// Microsoft Visual C++ ABI.
class MicrosoftMangleContext : public MangleContext {
public:
  MicrosoftMangleContext(ASTContext &Context,
                         Diagnostic &Diags) : MangleContext(Context, Diags) { }
  virtual bool shouldMangleDeclName(const NamedDecl *D);
  virtual void mangleName(const NamedDecl *D, llvm::raw_svector_ostream &Out);
  virtual void mangleThunk(const CXXMethodDecl *MD,
                           const ThunkInfo &Thunk,
                           llvm::SmallVectorImpl<char> &);
  virtual void mangleCXXDtorThunk(const CXXDestructorDecl *DD, CXXDtorType Type,
                                  const ThisAdjustment &ThisAdjustment,
                                  llvm::SmallVectorImpl<char> &);
  virtual void mangleCXXVTable(const CXXRecordDecl *RD,
                               llvm::SmallVectorImpl<char> &);
  virtual void mangleCXXVTT(const CXXRecordDecl *RD,
                            llvm::SmallVectorImpl<char> &);
  virtual void mangleCXXCtorVTable(const CXXRecordDecl *RD, int64_t Offset,
                                   const CXXRecordDecl *Type,
                                   llvm::SmallVectorImpl<char> &);
  virtual void mangleCXXRTTI(QualType T, llvm::SmallVectorImpl<char> &);
  virtual void mangleCXXRTTIName(QualType T, llvm::SmallVectorImpl<char> &);
  virtual void mangleCXXCtor(const CXXConstructorDecl *D, CXXCtorType Type,
                             llvm::raw_svector_ostream &);
  virtual void mangleCXXDtor(const CXXDestructorDecl *D, CXXDtorType Type,
                             llvm::raw_svector_ostream &);
  virtual void mangleReferenceTemporary(const clang::VarDecl *,
                                        llvm::SmallVectorImpl<char> &);
};

}

static bool isInCLinkageSpecification(const Decl *D) {
  D = D->getCanonicalDecl();
  for (const DeclContext *DC = D->getDeclContext();
       !DC->isTranslationUnit(); DC = DC->getParent()) {
    if (const LinkageSpecDecl *Linkage = dyn_cast<LinkageSpecDecl>(DC))
      return Linkage->getLanguage() == LinkageSpecDecl::lang_c;
  }

  return false;
}

bool MicrosoftMangleContext::shouldMangleDeclName(const NamedDecl *D) {
  // In C, functions with no attributes never need to be mangled. Fastpath them.
  if (!getASTContext().getLangOptions().CPlusPlus && !D->hasAttrs())
    return false;

  // Any decl can be declared with __asm("foo") on it, and this takes precedence
  // over all other naming in the .o file.
  if (D->hasAttr<AsmLabelAttr>())
    return true;

  // Clang's "overloadable" attribute extension to C/C++ implies name mangling
  // (always) as does passing a C++ member function and a function
  // whose name is not a simple identifier.
  const FunctionDecl *FD = dyn_cast<FunctionDecl>(D);
  if (FD && (FD->hasAttr<OverloadableAttr>() || isa<CXXMethodDecl>(FD) ||
             !FD->getDeclName().isIdentifier()))
    return true;

  // Otherwise, no mangling is done outside C++ mode.
  if (!getASTContext().getLangOptions().CPlusPlus)
    return false;

  // Variables at global scope with internal linkage are not mangled.
  if (!FD) {
    const DeclContext *DC = D->getDeclContext();
    if (DC->isTranslationUnit() && D->getLinkage() == InternalLinkage)
      return false;
  }

  // C functions and "main" are not mangled.
  if ((FD && FD->isMain()) || isInCLinkageSpecification(D))
    return false;

  return true;
}

void MicrosoftCXXNameMangler::mangle(const NamedDecl *D,
                                     llvm::StringRef Prefix) {
  // MSVC doesn't mangle C++ names the same way it mangles extern "C" names.
  // Therefore it's really important that we don't decorate the
  // name with leading underscores or leading/trailing at signs. So, emit a
  // asm marker at the start so we get the name right.
  Out << '\01';  // LLVM IR Marker for __asm("foo")

  // Any decl can be declared with __asm("foo") on it, and this takes precedence
  // over all other naming in the .o file.
  if (const AsmLabelAttr *ALA = D->getAttr<AsmLabelAttr>()) {
    // If we have an asm name, then we use it as the mangling.
    Out << ALA->getLabel();
    return;
  }

  // <mangled-name> ::= ? <name> <type-encoding>
  Out << Prefix;
  mangleName(D);
  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
    mangleFunctionEncoding(FD);
  else if (const VarDecl *VD = dyn_cast<VarDecl>(D))
    mangleVariableEncoding(VD);
  // TODO: Fields? Can MSVC even mangle them?
}

void MicrosoftCXXNameMangler::mangleFunctionEncoding(const FunctionDecl *FD) {
  // <type-encoding> ::= <function-class> <function-type>

  // Don't mangle in the type if this isn't a decl we should typically mangle.
  if (!Context.shouldMangleDeclName(FD))
    return;
  
  // We should never ever see a FunctionNoProtoType at this point.
  // We don't even know how to mangle their types anyway :).
  const FunctionProtoType *FT = cast<FunctionProtoType>(FD->getType());

  bool InStructor = false, InInstMethod = false;
  const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD);
  if (MD) {
    if (MD->isInstance())
      InInstMethod = true;
    if (isa<CXXConstructorDecl>(MD) || isa<CXXDestructorDecl>(MD))
      InStructor = true;
  }

  // First, the function class.
  mangleFunctionClass(FD);

  mangleType(FT, FD, InStructor, InInstMethod);
}

void MicrosoftCXXNameMangler::mangleVariableEncoding(const VarDecl *VD) {
  // <type-encoding> ::= <storage-class> <variable-type>
  // <storage-class> ::= 0  # private static member
  //                 ::= 1  # protected static member
  //                 ::= 2  # public static member
  //                 ::= 3  # global
  //                 ::= 4  # static local
  
  // The first character in the encoding (after the name) is the storage class.
  if (VD->isStaticDataMember()) {
    // If it's a static member, it also encodes the access level.
    switch (VD->getAccess()) {
      default:
      case AS_private: Out << '0'; break;
      case AS_protected: Out << '1'; break;
      case AS_public: Out << '2'; break;
    }
  }
  else if (!VD->isStaticLocal())
    Out << '3';
  else
    Out << '4';
  // Now mangle the type.
  // <variable-type> ::= <type> <cvr-qualifiers>
  //                 ::= <type> A # pointers, references, arrays
  // Pointers and references are odd. The type of 'int * const foo;' gets
  // mangled as 'QAHA' instead of 'PAHB', for example.
  QualType Ty = VD->getType();
  if (Ty->isPointerType() || Ty->isReferenceType()) {
    mangleType(Ty);
    Out << 'A';
  } else if (Ty->isArrayType()) {
    // Global arrays are funny, too.
    mangleType(cast<ArrayType>(Ty.getTypePtr()), true);
    Out << 'A';
  } else {
    mangleType(Ty.getLocalUnqualifiedType());
    mangleQualifiers(Ty.getLocalQualifiers(), false);
  }
}

void MicrosoftCXXNameMangler::mangleName(const NamedDecl *ND) {
  // <name> ::= <unscoped-name> {[<named-scope>]+ | [<nested-name>]}? @
  const DeclContext *DC = ND->getDeclContext();

  // Always start with the unqualified name.
  mangleUnqualifiedName(ND);    

  // If this is an extern variable declared locally, the relevant DeclContext
  // is that of the containing namespace, or the translation unit.
  if (isa<FunctionDecl>(DC) && ND->hasLinkage())
    while (!DC->isNamespace() && !DC->isTranslationUnit())
      DC = DC->getParent();

  manglePostfix(DC);

  // Terminate the whole name with an '@'.
  Out << '@';
}

void MicrosoftCXXNameMangler::mangleNumber(int64_t Number) {
  // <number> ::= [?] <decimal digit> # <= 9
  //          ::= [?] <hex digit>+ @ # > 9; A = 0, B = 1, etc...
  if (Number < 0) {
    Out << '?';
    Number = -Number;
  }
  if (Number >= 1 && Number <= 10) {
    Out << Number-1;
  } else {
    // We have to build up the encoding in reverse order, so it will come
    // out right when we write it out.
    char Encoding[16];
    char *EndPtr = Encoding+sizeof(Encoding);
    char *CurPtr = EndPtr;
    while (Number) {
      *--CurPtr = 'A' + (Number % 16);
      Number /= 16;
    }
    Out.write(CurPtr, EndPtr-CurPtr);
    Out << '@';
  }
}

void
MicrosoftCXXNameMangler::mangleUnqualifiedName(const NamedDecl *ND,
                                               DeclarationName Name) {
  //  <unqualified-name> ::= <operator-name>
  //                     ::= <ctor-dtor-name>
  //                     ::= <source-name>
  switch (Name.getNameKind()) {
    case DeclarationName::Identifier: {
      if (const IdentifierInfo *II = Name.getAsIdentifierInfo()) {
        mangleSourceName(II);
        break;
      }
      
      // Otherwise, an anonymous entity.  We must have a declaration.
      assert(ND && "mangling empty name without declaration");
      
      if (const NamespaceDecl *NS = dyn_cast<NamespaceDecl>(ND)) {
        if (NS->isAnonymousNamespace()) {
          Out << "?A";
          break;
        }
      }
      
      // We must have an anonymous struct.
      const TagDecl *TD = cast<TagDecl>(ND);
      if (const TypedefDecl *D = TD->getTypedefForAnonDecl()) {
        assert(TD->getDeclContext() == D->getDeclContext() &&
               "Typedef should not be in another decl context!");
        assert(D->getDeclName().getAsIdentifierInfo() &&
               "Typedef was not named!");
        mangleSourceName(D->getDeclName().getAsIdentifierInfo());
        break;
      }

      // When VC encounters an anonymous type with no tag and no typedef,
      // it literally emits '<unnamed-tag>'.
      Out << "<unnamed-tag>";
      break;
    }
      
    case DeclarationName::ObjCZeroArgSelector:
    case DeclarationName::ObjCOneArgSelector:
    case DeclarationName::ObjCMultiArgSelector:
      assert(false && "Can't mangle Objective-C selector names here!");
      break;
      
    case DeclarationName::CXXConstructorName:
      assert(false && "Can't mangle constructors yet!");
      break;
      
    case DeclarationName::CXXDestructorName:
      assert(false && "Can't mangle destructors yet!");
      break;
      
    case DeclarationName::CXXConversionFunctionName:
      // <operator-name> ::= ?B # (cast)
      // The target type is encoded as the return type.
      Out << "?B";
      break;
      
    case DeclarationName::CXXOperatorName:
      mangleOperatorName(Name.getCXXOverloadedOperator());
      break;
      
    case DeclarationName::CXXLiteralOperatorName:
      // FIXME: Was this added in VS2010? Does MS even know how to mangle this?
      assert(false && "Don't know how to mangle literal operators yet!");
      break;
      
    case DeclarationName::CXXUsingDirective:
      assert(false && "Can't mangle a using directive name!");
      break;
  }
}

void MicrosoftCXXNameMangler::manglePostfix(const DeclContext *DC,
                                            bool NoFunction) {
  // <postfix> ::= <unqualified-name> [<postfix>]
  //           ::= <template-postfix> <template-args> [<postfix>]
  //           ::= <template-param>
  //           ::= <substitution> [<postfix>]

  if (!DC) return;

  while (isa<LinkageSpecDecl>(DC))
    DC = DC->getParent();

  if (DC->isTranslationUnit())
    return;

  if (const BlockDecl *BD = dyn_cast<BlockDecl>(DC)) {
    Context.mangleBlock(BD, Out);
    Out << '@';
    return manglePostfix(DC->getParent(), NoFunction);
  }

  if (NoFunction && (isa<FunctionDecl>(DC) || isa<ObjCMethodDecl>(DC)))
    return;
  else if (const ObjCMethodDecl *Method = dyn_cast<ObjCMethodDecl>(DC))
    mangleObjCMethodName(Method);
  else {
    mangleUnqualifiedName(cast<NamedDecl>(DC));
    manglePostfix(DC->getParent(), NoFunction);
  }
}

void MicrosoftCXXNameMangler::mangleOperatorName(OverloadedOperatorKind OO) {
  switch (OO) {
  //                     ?0 # constructor
  //                     ?1 # destructor
  // <operator-name> ::= ?2 # new
  case OO_New: Out << "?2"; break;
  // <operator-name> ::= ?3 # delete
  case OO_Delete: Out << "?3"; break;
  // <operator-name> ::= ?4 # =
  case OO_Equal: Out << "?4"; break;
  // <operator-name> ::= ?5 # >>
  case OO_GreaterGreater: Out << "?5"; break;
  // <operator-name> ::= ?6 # <<
  case OO_LessLess: Out << "?6"; break;
  // <operator-name> ::= ?7 # !
  case OO_Exclaim: Out << "?7"; break;
  // <operator-name> ::= ?8 # ==
  case OO_EqualEqual: Out << "?8"; break;
  // <operator-name> ::= ?9 # !=
  case OO_ExclaimEqual: Out << "?9"; break;
  // <operator-name> ::= ?A # []
  case OO_Subscript: Out << "?A"; break;
  //                     ?B # conversion
  // <operator-name> ::= ?C # ->
  case OO_Arrow: Out << "?C"; break;
  // <operator-name> ::= ?D # *
  case OO_Star: Out << "?D"; break;
  // <operator-name> ::= ?E # ++
  case OO_PlusPlus: Out << "?E"; break;
  // <operator-name> ::= ?F # --
  case OO_MinusMinus: Out << "?F"; break;
  // <operator-name> ::= ?G # -
  case OO_Minus: Out << "?G"; break;
  // <operator-name> ::= ?H # +
  case OO_Plus: Out << "?H"; break;
  // <operator-name> ::= ?I # &
  case OO_Amp: Out << "?I"; break;
  // <operator-name> ::= ?J # ->*
  case OO_ArrowStar: Out << "?J"; break;
  // <operator-name> ::= ?K # /
  case OO_Slash: Out << "?K"; break;
  // <operator-name> ::= ?L # %
  case OO_Percent: Out << "?L"; break;
  // <operator-name> ::= ?M # <
  case OO_Less: Out << "?M"; break;
  // <operator-name> ::= ?N # <=
  case OO_LessEqual: Out << "?N"; break;
  // <operator-name> ::= ?O # >
  case OO_Greater: Out << "?O"; break;
  // <operator-name> ::= ?P # >=
  case OO_GreaterEqual: Out << "?P"; break;
  // <operator-name> ::= ?Q # ,
  case OO_Comma: Out << "?Q"; break;
  // <operator-name> ::= ?R # ()
  case OO_Call: Out << "?R"; break;
  // <operator-name> ::= ?S # ~
  case OO_Tilde: Out << "?S"; break;
  // <operator-name> ::= ?T # ^
  case OO_Caret: Out << "?T"; break;
  // <operator-name> ::= ?U # |
  case OO_Pipe: Out << "?U"; break;
  // <operator-name> ::= ?V # &&
  case OO_AmpAmp: Out << "?V"; break;
  // <operator-name> ::= ?W # ||
  case OO_PipePipe: Out << "?W"; break;
  // <operator-name> ::= ?X # *=
  case OO_StarEqual: Out << "?X"; break;
  // <operator-name> ::= ?Y # +=
  case OO_PlusEqual: Out << "?Y"; break;
  // <operator-name> ::= ?Z # -=
  case OO_MinusEqual: Out << "?Z"; break;
  // <operator-name> ::= ?_0 # /=
  case OO_SlashEqual: Out << "?_0"; break;
  // <operator-name> ::= ?_1 # %=
  case OO_PercentEqual: Out << "?_1"; break;
  // <operator-name> ::= ?_2 # >>=
  case OO_GreaterGreaterEqual: Out << "?_2"; break;
  // <operator-name> ::= ?_3 # <<=
  case OO_LessLessEqual: Out << "?_3"; break;
  // <operator-name> ::= ?_4 # &=
  case OO_AmpEqual: Out << "?_4"; break;
  // <operator-name> ::= ?_5 # |=
  case OO_PipeEqual: Out << "?_5"; break;
  // <operator-name> ::= ?_6 # ^=
  case OO_CaretEqual: Out << "?_6"; break;
  //                     ?_7 # vftable
  //                     ?_8 # vbtable
  //                     ?_9 # vcall
  //                     ?_A # typeof
  //                     ?_B # local static guard
  //                     ?_C # string
  //                     ?_D # vbase destructor
  //                     ?_E # vector deleting destructor
  //                     ?_F # default constructor closure
  //                     ?_G # scalar deleting destructor
  //                     ?_H # vector constructor iterator
  //                     ?_I # vector destructor iterator
  //                     ?_J # vector vbase constructor iterator
  //                     ?_K # virtual displacement map
  //                     ?_L # eh vector constructor iterator
  //                     ?_M # eh vector destructor iterator
  //                     ?_N # eh vector vbase constructor iterator
  //                     ?_O # copy constructor closure
  //                     ?_P<name> # udt returning <name>
  //                     ?_Q # <unknown>
  //                     ?_R0 # RTTI Type Descriptor
  //                     ?_R1 # RTTI Base Class Descriptor at (a,b,c,d)
  //                     ?_R2 # RTTI Base Class Array
  //                     ?_R3 # RTTI Class Hierarchy Descriptor
  //                     ?_R4 # RTTI Complete Object Locator
  //                     ?_S # local vftable
  //                     ?_T # local vftable constructor closure
  // <operator-name> ::= ?_U # new[]
  case OO_Array_New: Out << "?_U"; break;
  // <operator-name> ::= ?_V # delete[]
  case OO_Array_Delete: Out << "?_V"; break;
    
  case OO_Conditional:
    assert(false && "Don't know how to mangle ?:");
    break;
    
  case OO_None:
  case NUM_OVERLOADED_OPERATORS:
    assert(false && "Not an overloaded operator");
    break;
  }
}

void MicrosoftCXXNameMangler::mangleSourceName(const IdentifierInfo *II) {
  // <source name> ::= <identifier> @
  Out << II->getName() << '@';
}

void MicrosoftCXXNameMangler::mangleObjCMethodName(const ObjCMethodDecl *MD) {
  llvm::SmallString<64> Buffer;
  Context.mangleObjCMethodName(MD, Buffer);
  Out << Buffer;
}

void MicrosoftCXXNameMangler::mangleQualifiers(Qualifiers Quals,
                                               bool IsMember) {
  // <cvr-qualifiers> ::= [E] [F] [I] <base-cvr-qualifiers>
  // 'E' means __ptr64 (32-bit only); 'F' means __unaligned (32/64-bit only);
  // 'I' means __restrict (32/64-bit).
  // Note that the MSVC __restrict keyword isn't the same as the C99 restrict
  // keyword!
  // <base-cvr-qualifiers> ::= A  # near
  //                       ::= B  # near const
  //                       ::= C  # near volatile
  //                       ::= D  # near const volatile
  //                       ::= E  # far (16-bit)
  //                       ::= F  # far const (16-bit)
  //                       ::= G  # far volatile (16-bit)
  //                       ::= H  # far const volatile (16-bit)
  //                       ::= I  # huge (16-bit)
  //                       ::= J  # huge const (16-bit)
  //                       ::= K  # huge volatile (16-bit)
  //                       ::= L  # huge const volatile (16-bit)
  //                       ::= M <basis> # based
  //                       ::= N <basis> # based const
  //                       ::= O <basis> # based volatile
  //                       ::= P <basis> # based const volatile
  //                       ::= Q  # near member
  //                       ::= R  # near const member
  //                       ::= S  # near volatile member
  //                       ::= T  # near const volatile member
  //                       ::= U  # far member (16-bit)
  //                       ::= V  # far const member (16-bit)
  //                       ::= W  # far volatile member (16-bit)
  //                       ::= X  # far const volatile member (16-bit)
  //                       ::= Y  # huge member (16-bit)
  //                       ::= Z  # huge const member (16-bit)
  //                       ::= 0  # huge volatile member (16-bit)
  //                       ::= 1  # huge const volatile member (16-bit)
  //                       ::= 2 <basis> # based member
  //                       ::= 3 <basis> # based const member
  //                       ::= 4 <basis> # based volatile member
  //                       ::= 5 <basis> # based const volatile member
  //                       ::= 6  # near function (pointers only)
  //                       ::= 7  # far function (pointers only)
  //                       ::= 8  # near method (pointers only)
  //                       ::= 9  # far method (pointers only)
  //                       ::= _A <basis> # based function (pointers only)
  //                       ::= _B <basis> # based function (far?) (pointers only)
  //                       ::= _C <basis> # based method (pointers only)
  //                       ::= _D <basis> # based method (far?) (pointers only)
  //                       ::= _E # block (Clang)
  // <basis> ::= 0 # __based(void)
  //         ::= 1 # __based(segment)?
  //         ::= 2 <name> # __based(name)
  //         ::= 3 # ?
  //         ::= 4 # ?
  //         ::= 5 # not really based
  if (!IsMember) {
    if (!Quals.hasVolatile()) {
      if (!Quals.hasConst())
        Out << 'A';
      else
        Out << 'B';
    } else {
      if (!Quals.hasConst())
        Out << 'C';
      else
        Out << 'D';
    }
  } else {
    if (!Quals.hasVolatile()) {
      if (!Quals.hasConst())
        Out << 'Q';
      else
        Out << 'R';
    } else {
      if (!Quals.hasConst())
        Out << 'S';
      else
        Out << 'T';
    }
  }

  // FIXME: For now, just drop all extension qualifiers on the floor.
}

void MicrosoftCXXNameMangler::mangleType(QualType T) {
  // Only operate on the canonical type!
  T = getASTContext().getCanonicalType(T);
  
  Qualifiers Quals = T.getLocalQualifiers();
  if (Quals) {
    // We have to mangle these now, while we still have enough information.
    // <pointer-cvr-qualifiers> ::= P  # pointer
    //                          ::= Q  # const pointer
    //                          ::= R  # volatile pointer
    //                          ::= S  # const volatile pointer
    if (T->isAnyPointerType() || T->isMemberPointerType() ||
        T->isBlockPointerType()) {
      if (!Quals.hasVolatile())
        Out << 'Q';
      else {
        if (!Quals.hasConst())
          Out << 'R';
        else
          Out << 'S';
      }
    } else
      // Just emit qualifiers like normal.
      // NB: When we mangle a pointer/reference type, and the pointee
      // type has no qualifiers, the lack of qualifier gets mangled
      // in there.
      mangleQualifiers(Quals, false);
  } else if (T->isAnyPointerType() || T->isMemberPointerType() ||
             T->isBlockPointerType()) {
    Out << 'P';
  }
  switch (T->getTypeClass()) {
#define ABSTRACT_TYPE(CLASS, PARENT)
#define NON_CANONICAL_TYPE(CLASS, PARENT) \
case Type::CLASS: \
llvm_unreachable("can't mangle non-canonical type " #CLASS "Type"); \
return;
#define TYPE(CLASS, PARENT) \
case Type::CLASS: \
mangleType(static_cast<const CLASS##Type*>(T.getTypePtr())); \
break;
#include "clang/AST/TypeNodes.def"
  }
}

void MicrosoftCXXNameMangler::mangleType(const BuiltinType *T) {
  //  <type>         ::= <builtin-type>
  //  <builtin-type> ::= X  # void
  //                 ::= C  # signed char
  //                 ::= D  # char
  //                 ::= E  # unsigned char
  //                 ::= F  # short
  //                 ::= G  # unsigned short (or wchar_t if it's not a builtin)
  //                 ::= H  # int
  //                 ::= I  # unsigned int
  //                 ::= J  # long
  //                 ::= K  # unsigned long
  //                     L  # <none>
  //                 ::= M  # float
  //                 ::= N  # double
  //                 ::= O  # long double (__float80 is mangled differently)
  //                 ::= _D # __int8 (yup, it's a distinct type in MSVC)
  //                 ::= _E # unsigned __int8
  //                 ::= _F # __int16
  //                 ::= _G # unsigned __int16
  //                 ::= _H # __int32
  //                 ::= _I # unsigned __int32
  //                 ::= _J # long long, __int64
  //                 ::= _K # unsigned long long, __int64
  //                 ::= _L # __int128
  //                 ::= _M # unsigned __int128
  //                 ::= _N # bool
  //                     _O # <array in parameter>
  //                 ::= _T # __float80 (Intel)
  //                 ::= _W # wchar_t
  //                 ::= _Z # __float80 (Digital Mars)
  switch (T->getKind()) {
  case BuiltinType::Void: Out << 'X'; break;
  case BuiltinType::SChar: Out << 'C'; break;
  case BuiltinType::Char_U: case BuiltinType::Char_S: Out << 'D'; break;
  case BuiltinType::UChar: Out << 'E'; break;
  case BuiltinType::Short: Out << 'F'; break;
  case BuiltinType::UShort: Out << 'G'; break;
  case BuiltinType::Int: Out << 'H'; break;
  case BuiltinType::UInt: Out << 'I'; break;
  case BuiltinType::Long: Out << 'J'; break;
  case BuiltinType::ULong: Out << 'K'; break;
  case BuiltinType::Float: Out << 'M'; break;
  case BuiltinType::Double: Out << 'N'; break;
  // TODO: Determine size and mangle accordingly
  case BuiltinType::LongDouble: Out << 'O'; break;
  // TODO: __int8 and friends
  case BuiltinType::LongLong: Out << "_J"; break;
  case BuiltinType::ULongLong: Out << "_K"; break;
  case BuiltinType::Int128: Out << "_L"; break;
  case BuiltinType::UInt128: Out << "_M"; break;
  case BuiltinType::Bool: Out << "_N"; break;
  case BuiltinType::WChar_S:
  case BuiltinType::WChar_U: Out << "_W"; break;

  case BuiltinType::Overload:
  case BuiltinType::Dependent:
    assert(false &&
           "Overloaded and dependent types shouldn't get to name mangling");
    break;
  case BuiltinType::UndeducedAuto:
    assert(0 && "Should not see undeduced auto here");
    break;
  case BuiltinType::ObjCId: Out << "PAUobjc_object@@"; break;
  case BuiltinType::ObjCClass: Out << "PAUobjc_class@@"; break;
  case BuiltinType::ObjCSel: Out << "PAUobjc_selector@@"; break;

  case BuiltinType::Char16:
  case BuiltinType::Char32:
  case BuiltinType::NullPtr:
    assert(false && "Don't know how to mangle this type");
    break;
  }
}

// <type>          ::= <function-type>
void MicrosoftCXXNameMangler::mangleType(const FunctionProtoType *T) {
  // Structors only appear in decls, so at this point we know it's not a
  // structor type.
  // I'll probably have mangleType(MemberPointerType) call the mangleType()
  // method directly.
  mangleType(T, NULL, false, false);
}
void MicrosoftCXXNameMangler::mangleType(const FunctionNoProtoType *T) {
  llvm_unreachable("Can't mangle K&R function prototypes");
}

void MicrosoftCXXNameMangler::mangleType(const FunctionType *T,
                                         const FunctionDecl *D,
                                         bool IsStructor,
                                         bool IsInstMethod) {
  // <function-type> ::= <this-cvr-qualifiers> <calling-convention>
  //                     <return-type> <argument-list> <throw-spec>
  const FunctionProtoType *Proto = cast<FunctionProtoType>(T);

  // If this is a C++ instance method, mangle the CVR qualifiers for the
  // this pointer.
  if (IsInstMethod)
    mangleQualifiers(Qualifiers::fromCVRMask(Proto->getTypeQuals()), false);

  mangleCallingConvention(T, IsInstMethod);

  // <return-type> ::= <type>
  //               ::= @ # structors (they have no declared return type)
  if (IsStructor)
    Out << '@';
  else
    mangleType(Proto->getResultType());

  // <argument-list> ::= X # void
  //                 ::= <type>+ @
  //                 ::= <type>* Z # varargs
  if (Proto->getNumArgs() == 0 && !Proto->isVariadic()) {
    Out << 'X';
  } else {
    if (D) {
      // If we got a decl, use the "types-as-written" to make sure arrays
      // get mangled right.
      for (FunctionDecl::param_const_iterator Parm = D->param_begin(),
           ParmEnd = D->param_end();
           Parm != ParmEnd; ++Parm)
        mangleType((*Parm)->getTypeSourceInfo()->getType());
    } else {
      for (FunctionProtoType::arg_type_iterator Arg = Proto->arg_type_begin(),
           ArgEnd = Proto->arg_type_end();
           Arg != ArgEnd; ++Arg)
        mangleType(*Arg);
    }
    // <builtin-type>      ::= Z  # ellipsis
    if (Proto->isVariadic())
      Out << 'Z';
    else
      Out << '@';
  }

  mangleThrowSpecification(Proto);
}

void MicrosoftCXXNameMangler::mangleFunctionClass(const FunctionDecl *FD) {
  // <function-class> ::= A # private: near
  //                  ::= B # private: far
  //                  ::= C # private: static near
  //                  ::= D # private: static far
  //                  ::= E # private: virtual near
  //                  ::= F # private: virtual far
  //                  ::= G # private: thunk near
  //                  ::= H # private: thunk far
  //                  ::= I # protected: near
  //                  ::= J # protected: far
  //                  ::= K # protected: static near
  //                  ::= L # protected: static far
  //                  ::= M # protected: virtual near
  //                  ::= N # protected: virtual far
  //                  ::= O # protected: thunk near
  //                  ::= P # protected: thunk far
  //                  ::= Q # public: near
  //                  ::= R # public: far
  //                  ::= S # public: static near
  //                  ::= T # public: static far
  //                  ::= U # public: virtual near
  //                  ::= V # public: virtual far
  //                  ::= W # public: thunk near
  //                  ::= X # public: thunk far
  //                  ::= Y # global near
  //                  ::= Z # global far
  if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) {
    switch (MD->getAccess()) {
      default:
      case AS_private:
        if (MD->isStatic())
          Out << 'C';
        else if (MD->isVirtual())
          Out << 'E';
        else
          Out << 'A';
        break;
      case AS_protected:
        if (MD->isStatic())
          Out << 'K';
        else if (MD->isVirtual())
          Out << 'M';
        else
          Out << 'I';
        break;
      case AS_public:
        if (MD->isStatic())
          Out << 'S';
        else if (MD->isVirtual())
          Out << 'U';
        else
          Out << 'Q';
    }
  } else
    Out << 'Y';
}
void MicrosoftCXXNameMangler::mangleCallingConvention(const FunctionType *T,
                                                      bool IsInstMethod) {
  // <calling-convention> ::= A # __cdecl
  //                      ::= B # __export __cdecl
  //                      ::= C # __pascal
  //                      ::= D # __export __pascal
  //                      ::= E # __thiscall
  //                      ::= F # __export __thiscall
  //                      ::= G # __stdcall
  //                      ::= H # __export __stdcall
  //                      ::= I # __fastcall
  //                      ::= J # __export __fastcall
  // The 'export' calling conventions are from a bygone era
  // (*cough*Win16*cough*) when functions were declared for export with
  // that keyword. (It didn't actually export them, it just made them so
  // that they could be in a DLL and somebody from another module could call
  // them.)
  CallingConv CC = T->getCallConv();
  if (CC == CC_Default)
    CC = IsInstMethod ? getASTContext().getDefaultMethodCallConv() : CC_C;
  switch (CC) {
    case CC_Default:
    case CC_C: Out << 'A'; break;
    case CC_X86Pascal: Out << 'C'; break;
    case CC_X86ThisCall: Out << 'E'; break;
    case CC_X86StdCall: Out << 'G'; break;
    case CC_X86FastCall: Out << 'I'; break;
  }
}
void MicrosoftCXXNameMangler::mangleThrowSpecification(
                                                const FunctionProtoType *FT) {
  // <throw-spec> ::= Z # throw(...) (default)
  //              ::= @ # throw() or __declspec/__attribute__((nothrow))
  //              ::= <type>+
  // NOTE: Since the Microsoft compiler ignores throw specifications, they are
  // all actually mangled as 'Z'. (They're ignored because their associated
  // functionality isn't implemented, and probably never will be.)
  Out << 'Z';
}

void MicrosoftCXXNameMangler::mangleType(const UnresolvedUsingType *T) {
  assert(false && "Don't know how to mangle UnresolvedUsingTypes yet!");
}

// <type>        ::= <union-type> | <struct-type> | <class-type> | <enum-type>
// <union-type>  ::= T <name>
// <struct-type> ::= U <name>
// <class-type>  ::= V <name>
// <enum-type>   ::= W <size> <name>
void MicrosoftCXXNameMangler::mangleType(const EnumType *T) {
  mangleType(static_cast<const TagType*>(T));
}
void MicrosoftCXXNameMangler::mangleType(const RecordType *T) {
  mangleType(static_cast<const TagType*>(T));
}
void MicrosoftCXXNameMangler::mangleType(const TagType *T) {
  switch (T->getDecl()->getTagKind()) {
    case TTK_Union:
      Out << 'T';
      break;
    case TTK_Struct:
      Out << 'U';
      break;
    case TTK_Class:
      Out << 'V';
      break;
    case TTK_Enum:
      Out << 'W';
      Out << getASTContext().getTypeSizeInChars(
                cast<EnumDecl>(T->getDecl())->getIntegerType()).getQuantity();
      break;
  }
  mangleName(T->getDecl());
}

// <type>       ::= <array-type>
// <array-type> ::= P <cvr-qualifiers> [Y <dimension-count> <dimension>+]
//                                                  <element-type> # as global
//              ::= Q <cvr-qualifiers> [Y <dimension-count> <dimension>+]
//                                                  <element-type> # as param
// It's supposed to be the other way around, but for some strange reason, it
// isn't. Today this behavior is retained for the sole purpose of backwards
// compatibility.
void MicrosoftCXXNameMangler::mangleType(const ArrayType *T, bool IsGlobal) {
  // This isn't a recursive mangling, so now we have to do it all in this
  // one call.
  if (IsGlobal)
    Out << 'P';
  else
    Out << 'Q';
  mangleExtraDimensions(T->getElementType());
}
void MicrosoftCXXNameMangler::mangleType(const ConstantArrayType *T) {
  mangleType(static_cast<const ArrayType *>(T), false);
}
void MicrosoftCXXNameMangler::mangleType(const VariableArrayType *T) {
  mangleType(static_cast<const ArrayType *>(T), false);
}
void MicrosoftCXXNameMangler::mangleType(const DependentSizedArrayType *T) {
  mangleType(static_cast<const ArrayType *>(T), false);
}
void MicrosoftCXXNameMangler::mangleType(const IncompleteArrayType *T) {
  mangleType(static_cast<const ArrayType *>(T), false);
}
void MicrosoftCXXNameMangler::mangleExtraDimensions(QualType ElementTy) {
  llvm::SmallVector<llvm::APInt, 3> Dimensions;
  for (;;) {
    if (ElementTy->isConstantArrayType()) {
      const ConstantArrayType *CAT =
      static_cast<const ConstantArrayType *>(ElementTy.getTypePtr());
      Dimensions.push_back(CAT->getSize());
      ElementTy = CAT->getElementType();
    } else if (ElementTy->isVariableArrayType()) {
      assert(false && "Don't know how to mangle VLAs!");
    } else if (ElementTy->isDependentSizedArrayType()) {
      // The dependent expression has to be folded into a constant (TODO).
      assert(false && "Don't know how to mangle dependent-sized arrays!");
    } else if (ElementTy->isIncompleteArrayType()) continue;
    else break;
  }
  mangleQualifiers(ElementTy.getQualifiers(), false);
  // If there are any additional dimensions, mangle them now.
  if (Dimensions.size() > 0) {
    Out << 'Y';
    // <dimension-count> ::= <number> # number of extra dimensions
    mangleNumber(Dimensions.size());
    for (unsigned Dim = 0; Dim < Dimensions.size(); ++Dim) {
      mangleNumber(Dimensions[Dim].getLimitedValue());
    }
  }
  mangleType(ElementTy.getLocalUnqualifiedType());
}

// <type>                   ::= <pointer-to-member-type>
// <pointer-to-member-type> ::= <pointer-cvr-qualifiers> <cvr-qualifiers>
//                                                          <class name> <type>
void MicrosoftCXXNameMangler::mangleType(const MemberPointerType *T) {
  QualType PointeeType = T->getPointeeType();
  if (const FunctionProtoType *FPT = dyn_cast<FunctionProtoType>(PointeeType)) {
    Out << '8';
    mangleName(cast<RecordType>(T->getClass())->getDecl());
    mangleType(FPT, NULL, false, true);
  } else {
    mangleQualifiers(PointeeType.getQualifiers(), true);
    mangleName(cast<RecordType>(T->getClass())->getDecl());
    mangleType(PointeeType.getLocalUnqualifiedType());
  }
}

void MicrosoftCXXNameMangler::mangleType(const TemplateTypeParmType *T) {
  assert(false && "Don't know how to mangle TemplateTypeParmTypes yet!");
}

void MicrosoftCXXNameMangler::mangleType(
                                       const SubstTemplateTypeParmPackType *T) {
  assert(false && 
         "Don't know how to mangle SubstTemplateTypeParmPackTypes yet!");
}

// <type> ::= <pointer-type>
// <pointer-type> ::= <pointer-cvr-qualifiers> <cvr-qualifiers> <type>
void MicrosoftCXXNameMangler::mangleType(const PointerType *T) {
  QualType PointeeTy = T->getPointeeType();
  if (PointeeTy->isArrayType()) {
    // Pointers to arrays are mangled like arrays.
    mangleExtraDimensions(T->getPointeeType());
  } else if (PointeeTy->isFunctionType()) {
    // Function pointers are special.
    Out << '6';
    mangleType(static_cast<const FunctionType *>(PointeeTy.getTypePtr()),
               NULL, false, false);
  } else {
    if (!PointeeTy.hasQualifiers())
      // Lack of qualifiers is mangled as 'A'.
      Out << 'A';
    mangleType(PointeeTy);
  }
}
void MicrosoftCXXNameMangler::mangleType(const ObjCObjectPointerType *T) {
  // Object pointers never have qualifiers.
  Out << 'A';
  mangleType(T->getPointeeType());
}

// <type> ::= <reference-type>
// <reference-type> ::= A <cvr-qualifiers> <type>
void MicrosoftCXXNameMangler::mangleType(const LValueReferenceType *T) {
  Out << 'A';
  QualType PointeeTy = T->getPointeeType();
  if (!PointeeTy.hasQualifiers())
    // Lack of qualifiers is mangled as 'A'.
    Out << 'A';
  mangleType(PointeeTy);
}

void MicrosoftCXXNameMangler::mangleType(const RValueReferenceType *T) {
  assert(false && "Don't know how to mangle RValueReferenceTypes yet!");
}

void MicrosoftCXXNameMangler::mangleType(const ComplexType *T) {
  assert(false && "Don't know how to mangle ComplexTypes yet!");
}

void MicrosoftCXXNameMangler::mangleType(const VectorType *T) {
  assert(false && "Don't know how to mangle VectorTypes yet!");
}
void MicrosoftCXXNameMangler::mangleType(const ExtVectorType *T) {
  assert(false && "Don't know how to mangle ExtVectorTypes yet!");
}
void MicrosoftCXXNameMangler::mangleType(const DependentSizedExtVectorType *T) {
  assert(false && "Don't know how to mangle DependentSizedExtVectorTypes yet!");
}

void MicrosoftCXXNameMangler::mangleType(const ObjCInterfaceType *T) {
  // ObjC interfaces have structs underlying them.
  Out << 'U';
  mangleName(T->getDecl());
}

void MicrosoftCXXNameMangler::mangleType(const ObjCObjectType *T) {
  // We don't allow overloading by different protocol qualification,
  // so mangling them isn't necessary.
  mangleType(T->getBaseType());
}

void MicrosoftCXXNameMangler::mangleType(const BlockPointerType *T) {
  Out << "_E";
  mangleType(T->getPointeeType());
}

void MicrosoftCXXNameMangler::mangleType(const InjectedClassNameType *T) {
  assert(false && "Don't know how to mangle InjectedClassNameTypes yet!");
}

void MicrosoftCXXNameMangler::mangleType(const TemplateSpecializationType *T) {
  assert(false && "Don't know how to mangle TemplateSpecializationTypes yet!");
}

void MicrosoftCXXNameMangler::mangleType(const DependentNameType *T) {
  assert(false && "Don't know how to mangle DependentNameTypes yet!");
}

void MicrosoftCXXNameMangler::mangleType(
                                 const DependentTemplateSpecializationType *T) {
  assert(false &&
         "Don't know how to mangle DependentTemplateSpecializationTypes yet!");
}

void MicrosoftCXXNameMangler::mangleType(const PackExpansionType *T) {
  assert(false && "Don't know how to mangle PackExpansionTypes yet!");
}

void MicrosoftCXXNameMangler::mangleType(const TypeOfType *T) {
  assert(false && "Don't know how to mangle TypeOfTypes yet!");
}

void MicrosoftCXXNameMangler::mangleType(const TypeOfExprType *T) {
  assert(false && "Don't know how to mangle TypeOfExprTypes yet!");
}

void MicrosoftCXXNameMangler::mangleType(const DecltypeType *T) {
  assert(false && "Don't know how to mangle DecltypeTypes yet!");
}

void MicrosoftMangleContext::mangleName(const NamedDecl *D,
                                        llvm::raw_svector_ostream &Out) {
  assert((isa<FunctionDecl>(D) || isa<VarDecl>(D)) &&
         "Invalid mangleName() call, argument is not a variable or function!");
  assert(!isa<CXXConstructorDecl>(D) && !isa<CXXDestructorDecl>(D) &&
         "Invalid mangleName() call on 'structor decl!");

  PrettyStackTraceDecl CrashInfo(D, SourceLocation(),
                                 getASTContext().getSourceManager(),
                                 "Mangling declaration");

  MicrosoftCXXNameMangler Mangler(*this, Out);
  return Mangler.mangle(D);
}
void MicrosoftMangleContext::mangleThunk(const CXXMethodDecl *MD,
                                         const ThunkInfo &Thunk,
                                         llvm::SmallVectorImpl<char> &) {
  assert(false && "Can't yet mangle thunks!");
}
void MicrosoftMangleContext::mangleCXXDtorThunk(const CXXDestructorDecl *DD,
                                                CXXDtorType Type,
                                                const ThisAdjustment &,
                                                llvm::SmallVectorImpl<char> &) {
  assert(false && "Can't yet mangle destructor thunks!");
}
void MicrosoftMangleContext::mangleCXXVTable(const CXXRecordDecl *RD,
                                             llvm::SmallVectorImpl<char> &) {
  assert(false && "Can't yet mangle virtual tables!");
}
void MicrosoftMangleContext::mangleCXXVTT(const CXXRecordDecl *RD,
                                          llvm::SmallVectorImpl<char> &) {
  llvm_unreachable("The MS C++ ABI does not have virtual table tables!");
}
void MicrosoftMangleContext::mangleCXXCtorVTable(const CXXRecordDecl *RD,
                                                 int64_t Offset,
                                                 const CXXRecordDecl *Type,
                                                 llvm::SmallVectorImpl<char> &) {
  llvm_unreachable("The MS C++ ABI does not have constructor vtables!");
}
void MicrosoftMangleContext::mangleCXXRTTI(QualType T,
                                           llvm::SmallVectorImpl<char> &) {
  assert(false && "Can't yet mangle RTTI!");
}
void MicrosoftMangleContext::mangleCXXRTTIName(QualType T,
                                               llvm::SmallVectorImpl<char> &) {
  assert(false && "Can't yet mangle RTTI names!");
}
void MicrosoftMangleContext::mangleCXXCtor(const CXXConstructorDecl *D,
                                           CXXCtorType Type,
                                           llvm::raw_svector_ostream &) {
  assert(false && "Can't yet mangle constructors!");
}
void MicrosoftMangleContext::mangleCXXDtor(const CXXDestructorDecl *D,
                                           CXXDtorType Type,
                                           llvm::raw_svector_ostream &) {
  assert(false && "Can't yet mangle destructors!");
}
void MicrosoftMangleContext::mangleReferenceTemporary(const clang::VarDecl *,
                                                llvm::SmallVectorImpl<char> &) {
  assert(false && "Can't yet mangle reference temporaries!");
}

MangleContext *clang::createMicrosoftMangleContext(ASTContext &Context,
                                                   Diagnostic &Diags) {
  return new MicrosoftMangleContext(Context, Diags);
}