path: root/lib/CodeGen/MicrosoftCXXABI.cpp

//===--- MicrosoftCXXABI.cpp - Emit LLVM Code from ASTs for a Module ------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This provides C++ code generation targetting the Microsoft Visual C++ ABI.
// The class in this file generates structures that follow the Microsoft
// Visual C++ ABI, which is actually not very well documented at all outside
// of Microsoft.
//
//===----------------------------------------------------------------------===//

#include "CGCXXABI.h"
#include "CodeGenModule.h"
#include "Mangle.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/ExprCXX.h"
#include "CGVTables.h"

using namespace clang;
using namespace CodeGen;

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::SmallVectorImpl<char> &Res)
  : Context(C), Out(Res) { }

  llvm::raw_svector_ostream &getStream() { return Out; }

  void mangle(const NamedDecl *D, llvm::StringRef Prefix = "?");
  void mangleName(const NamedDecl *ND);

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 mangleObjCMethodName(const ObjCMethodDecl *MD);

};

/// 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::SmallVectorImpl<char> &);
  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 mangleGuardVariable(const VarDecl *D,
                                   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::SmallVectorImpl<char> &);
  virtual void mangleCXXDtor(const CXXDestructorDecl *D, CXXDtorType Type,
                             llvm::SmallVectorImpl<char> &);
};

class MicrosoftCXXABI : public CXXABI {
  MicrosoftMangleContext MangleCtx;
public:
  MicrosoftCXXABI(CodeGenModule &CGM)
   : MangleCtx(CGM.getContext(), CGM.getDiags()) {}

  MicrosoftMangleContext &getMangleContext() {
    return MangleCtx;
  }
};

}

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;

  // 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>
  Out << Prefix;
  mangleName(D);
  // TODO: Mangle type.
}

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::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;
      }

      // TODO: How does VC mangle anonymous structs?
      assert(false && "Don't know how to mangle anonymous types yet!");
      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:
      assert(</