CodeGenModule.cpp

QualType CodeGenModule::getObjCFastEnumerationStateType() {
  if (ObjCFastEnumerationStateType.isNull()) {
    RecordDecl *D = CreateRecordDecl(Context, TTK_Struct, 
                                     Context.getTranslationUnitDecl(),
                      &Context.Idents.get("__objcFastEnumerationState"));
    D->startDefinition();
    
    QualType FieldTypes[] = {
      Context.UnsignedLongTy,
      Context.getPointerType(Context.getObjCIdType()),
      Context.getPointerType(Context.UnsignedLongTy),
      Context.getConstantArrayType(Context.UnsignedLongTy,
                           llvm::APInt(32, 5), ArrayType::Normal, 0)
    };
    
    for (size_t i = 0; i < 4; ++i) {
      FieldDecl *Field = FieldDecl::Create(Context,
                                           D,
                                           SourceLocation(),
                                           SourceLocation(), 0,
                                           FieldTypes[i], /*TInfo=*/0,
                                           /*BitWidth=*/0,
                                           /*Mutable=*/false,
                                           /*HasInit=*/false);
      Field->setAccess(AS_public);
      D->addDecl(Field);
    }
    
    D->completeDefinition();
    ObjCFastEnumerationStateType = Context.getTagDeclType(D);
  }
  
  return ObjCFastEnumerationStateType;
}

/// GetStringForStringLiteral - Return the appropriate bytes for a
/// string literal, properly padded to match the literal type.
std::string CodeGenModule::GetStringForStringLiteral(const StringLiteral *E) {
  assert((E->isAscii() || E->isUTF8())
         && "Use GetConstantArrayFromStringLiteral for wide strings");
  const ASTContext &Context = getContext();
  const ConstantArrayType *CAT =
    Context.getAsConstantArrayType(E->getType());
  assert(CAT && "String isn't pointer or array!");

  // Resize the string to the right size.
  uint64_t RealLen = CAT->getSize().getZExtValue();

  std::string Str = E->getString().str();
  Str.resize(RealLen, '\0');

  return Str;
}

llvm::Constant *
CodeGenModule::GetConstantArrayFromStringLiteral(const StringLiteral *E) {
  assert(!E->getType()->isPointerType() && "Strings are always arrays");
  
  // Don't emit it as the address of the string, emit the string data itself
  // as an inline array.
  if (E->getCharByteWidth()==1) {
    return llvm::ConstantArray::get(VMContext,
                                    GetStringForStringLiteral(E), false);
  } else {
    llvm::ArrayType *AType =
      cast<llvm::ArrayType>(getTypes().ConvertType(E->getType()));
    llvm::Type *ElemTy = AType->getElementType();
    unsigned NumElements = AType->getNumElements();
    std::vector<llvm::Constant*> Elts;
    Elts.reserve(NumElements);
    
    for(unsigned i=0;i<E->getLength();++i) {
      unsigned value = E->getCodeUnit(i);
      llvm::Constant *C = llvm::ConstantInt::get(ElemTy,value,false);
      Elts.push_back(C);
    }
    for(unsigned i=E->getLength();i<NumElements;++i) {
      llvm::Constant *C = llvm::ConstantInt::get(ElemTy,0,false);
      Elts.push_back(C);
    }
    
    return llvm::ConstantArray::get(AType, Elts);
  }

}

/// GetAddrOfConstantStringFromLiteral - Return a pointer to a
/// constant array for the given string literal.
llvm::Constant *
CodeGenModule::GetAddrOfConstantStringFromLiteral(const StringLiteral *S) {
  // FIXME: This can be more efficient.
  // FIXME: We shouldn't need to bitcast the constant in the wide string case.
  CharUnits Align = getContext().getTypeAlignInChars(S->getType());
  if (S->isAscii() || S->isUTF8()) {
    return GetAddrOfConstantString(GetStringForStringLiteral(S),
                                   /* GlobalName */ 0,
                                   Align.getQuantity());
  }

  // FIXME: the following does not memoize wide strings
  llvm::Constant *C = GetConstantArrayFromStringLiteral(S);
  llvm::GlobalVariable *GV =
    new llvm::GlobalVariable(getModule(),C->getType(),
                             !Features.WritableStrings,
                             llvm::GlobalValue::PrivateLinkage,
                             C,".str");
  GV->setAlignment(Align.getQuantity());
  GV->setUnnamedAddr(true);
  
  return GV;
}

/// GetAddrOfConstantStringFromObjCEncode - Return a pointer to a constant
/// array for the given ObjCEncodeExpr node.
llvm::Constant *
CodeGenModule::GetAddrOfConstantStringFromObjCEncode(const ObjCEncodeExpr *E) {
  std::string Str;
  getContext().getObjCEncodingForType(E->getEncodedType(), Str);

  return GetAddrOfConstantCString(Str);
}


/// GenerateWritableString -- Creates storage for a string literal.
static llvm::GlobalVariable *GenerateStringLiteral(StringRef str,
                                             bool constant,
                                             CodeGenModule &CGM,
                                             const char *GlobalName,
                                             unsigned Alignment) {
  // Create Constant for this string literal. Don't add a '\0'.
  llvm::Constant *C =
      llvm::ConstantArray::get(CGM.getLLVMContext(), str, false);

  // Create a global variable for this string
  llvm::GlobalVariable *GV =
    new llvm::GlobalVariable(CGM.getModule(), C->getType(), constant,
                             llvm::GlobalValue::PrivateLinkage,
                             C, GlobalName);
  GV->setAlignment(Alignment);
  GV->setUnnamedAddr(true);
  return GV;
}

/// GetAddrOfConstantString - Returns a pointer to a character array
/// containing the literal. This contents are exactly that of the
/// given string, i.e. it will not be null terminated automatically;
/// see GetAddrOfConstantCString. Note that whether the result is
/// actually a pointer to an LLVM constant depends on
/// Feature.WriteableStrings.
///
/// The result has pointer to array type.
llvm::Constant *CodeGenModule::GetAddrOfConstantString(StringRef Str,
                                                       const char *GlobalName,
                                                       unsigned Alignment) {
  bool IsConstant = !Features.WritableStrings;

  // Get the default prefix if a name wasn't specified.
  if (!GlobalName)
    GlobalName = ".str";

  // Don't share any string literals if strings aren't constant.
  if (!IsConstant)
    return GenerateStringLiteral(Str, false, *this, GlobalName, Alignment);

  llvm::StringMapEntry<llvm::GlobalVariable *> &Entry =
    ConstantStringMap.GetOrCreateValue(Str);

  if (llvm::GlobalVariable *GV = Entry.getValue()) {
    if (Alignment > GV->getAlignment()) {
      GV->setAlignment(Alignment);
    }
    return GV;
  }

  // Create a global variable for this.
  llvm::GlobalVariable *GV = GenerateStringLiteral(Str, true, *this, GlobalName, Alignment);
  Entry.setValue(GV);
  return GV;
}

/// GetAddrOfConstantCString - Returns a pointer to a character
/// array containing the literal and a terminating '\0'
/// character. The result has pointer to array type.
llvm::Constant *CodeGenModule::GetAddrOfConstantCString(const std::string &Str,
                                                        const char *GlobalName,
                                                        unsigned Alignment) {
  StringRef StrWithNull(Str.c_str(), Str.size() + 1);
  return GetAddrOfConstantString(StrWithNull, GlobalName, Alignment);
}

/// EmitObjCPropertyImplementations - Emit information for synthesized
/// properties for an implementation.
void CodeGenModule::EmitObjCPropertyImplementations(const
                                                    ObjCImplementationDecl *D) {
  for (ObjCImplementationDecl::propimpl_iterator
         i = D->propimpl_begin(), e = D->propimpl_end(); i != e; ++i) {
    ObjCPropertyImplDecl *PID = *i;

    // Dynamic is just for type-checking.
    if (PID->getPropertyImplementation() == ObjCPropertyImplDecl::Synthesize) {
      ObjCPropertyDecl *PD = PID->getPropertyDecl();

      // Determine which methods need to be implemented, some may have
      // been overridden. Note that ::isSynthesized is not the method
      // we want, that just indicates if the decl came from a
      // property. What we want to know is if the method is defined in
      // this implementation.
      if (!D->getInstanceMethod(PD->getGetterName()))
        CodeGenFunction(*this).GenerateObjCGetter(
                                 const_cast<ObjCImplementationDecl *>(D), PID);
      if (!PD->isReadOnly() &&
          !D->getInstanceMethod(PD->getSetterName()))
        CodeGenFunction(*this).GenerateObjCSetter(
                                 const_cast<ObjCImplementationDecl *>(D), PID);
    }
  }
}

static bool needsDestructMethod(ObjCImplementationDecl *impl) {
  const ObjCInterfaceDecl *iface = impl->getClassInterface();
  for (const ObjCIvarDecl *ivar = iface->all_declared_ivar_begin();
       ivar; ivar = ivar->getNextIvar())
    if (ivar->getType().isDestructedType())
      return true;

  return false;
}

/// EmitObjCIvarInitializations - Emit information for ivar initialization
/// for an implementation.
void CodeGenModule::EmitObjCIvarInitializations(ObjCImplementationDecl *D) {
  // We might need a .cxx_destruct even if we don't have any ivar initializers.
  if (needsDestructMethod(D)) {
    IdentifierInfo *II = &getContext().Idents.get(".cxx_destruct");
    Selector cxxSelector = getContext().Selectors.getSelector(0, &II);
    ObjCMethodDecl *DTORMethod =
      ObjCMethodDecl::Create(getContext(), D->getLocation(), D->getLocation(),
                             cxxSelector, getContext().VoidTy, 0, D,
                             /*isInstance=*/true, /*isVariadic=*/false,
                          /*isSynthesized=*/true, /*isImplicitlyDeclared=*/true,
                             /*isDefined=*/false, ObjCMethodDecl::Required);
    D->addInstanceMethod(DTORMethod);
    CodeGenFunction(*this).GenerateObjCCtorDtorMethod(D, DTORMethod, false);
    D->setHasCXXStructors(true);
  }

  // If the implementation doesn't have any ivar initializers, we don't need
  // a .cxx_construct.
  if (D->getNumIvarInitializers() == 0)
    return;
  
  IdentifierInfo *II = &getContext().Idents.get(".cxx_construct");
  Selector cxxSelector = getContext().Selectors.getSelector(0, &II);
  // The constructor returns 'self'.
  ObjCMethodDecl *CTORMethod = ObjCMethodDecl::Create(getContext(), 
                                                D->getLocation(),
                                                D->getLocation(),
                                                cxxSelector,
                                                getContext().getObjCIdType(), 0, 
                                                D, /*isInstance=*/true,
                                                /*isVariadic=*/false,
                                                /*isSynthesized=*/true,
                                                /*isImplicitlyDeclared=*/true,
                                                /*isDefined=*/false,
                                                ObjCMethodDecl::Required);
  D->addInstanceMethod(CTORMethod);
  CodeGenFunction(*this).GenerateObjCCtorDtorMethod(D, CTORMethod, true);
  D->setHasCXXStructors(true);
}

/// EmitNamespace - Emit all declarations in a namespace.
void CodeGenModule::EmitNamespace(const NamespaceDecl *ND) {
  for (RecordDecl::decl_iterator I = ND->decls_begin(), E = ND->decls_end();
       I != E; ++I)
    EmitTopLevelDecl(*I);
}

// EmitLinkageSpec - Emit all declarations in a linkage spec.
void CodeGenModule::EmitLinkageSpec(const LinkageSpecDecl *LSD) {
  if (LSD->getLanguage() != LinkageSpecDecl::lang_c &&
      LSD->getLanguage() != LinkageSpecDecl::lang_cxx) {
    ErrorUnsupported(LSD, "linkage spec");
    return;
  }

  for (RecordDecl::decl_iterator I = LSD->decls_begin(), E = LSD->decls_end();
       I != E; ++I)
    EmitTopLevelDecl(*I);
}

/// EmitTopLevelDecl - Emit code for a single top level declaration.
void CodeGenModule::EmitTopLevelDecl(Decl *D) {
  // If an error has occurred, stop code generation, but continue
  // parsing and semantic analysis (to ensure all warnings and errors
  // are emitted).
  if (Diags.hasErrorOccurred())
    return;

  // Ignore dependent declarations.
  if (D->getDeclContext() && D->getDeclContext()->isDependentContext())
    return;

  switch (D->getKind()) {
  case Decl::CXXConversion:
  case Decl::CXXMethod:
  case Decl::Function:
    // Skip function templates
    if (cast<FunctionDecl>(D)->getDescribedFunctionTemplate() ||
        cast<FunctionDecl>(D)->isLateTemplateParsed())
      return;

    EmitGlobal(cast<FunctionDecl>(D));
    break;
      
  case Decl::Var:
    EmitGlobal(cast<VarDecl>(D));
    break;

  // Indirect fields from global anonymous structs and unions can be
  // ignored; only the actual variable requires IR gen support.
  case Decl::IndirectField:
    break;

  // C++ Decls
  case Decl::Namespace:
    EmitNamespace(cast<NamespaceDecl>(D));
    break;
    // No code generation needed.
  case Decl::UsingShadow:
  case Decl::Using:
  case Decl::UsingDirective:
  case Decl::ClassTemplate:
  case Decl::FunctionTemplate:
  case Decl::TypeAliasTemplate:
  case Decl::NamespaceAlias:
  case Decl::Block:
    break;
  case Decl::CXXConstructor:
    // Skip function templates
    if (cast<FunctionDecl>(D)->getDescribedFunctionTemplate() ||
        cast<FunctionDecl>(D)->isLateTemplateParsed())
      return;
      
    EmitCXXConstructors(cast<CXXConstructorDecl>(D));
    break;
  case Decl::CXXDestructor:
    if (cast<FunctionDecl>(D)->isLateTemplateParsed())
      return;
    EmitCXXDestructors(cast<CXXDestructorDecl>(D));
    break;

  case Decl::StaticAssert:
    // Nothing to do.
    break;

  // Objective-C Decls

  // Forward declarations, no (immediate) code generation.
  case Decl::ObjCClass:
  case Decl::ObjCForwardProtocol:
  case Decl::ObjCInterface:
    break;
  
  case Decl::ObjCCategory: {
    ObjCCategoryDecl *CD = cast<ObjCCategoryDecl>(D);
    if (CD->IsClassExtension() && CD->hasSynthBitfield())
      Context.ResetObjCLayout(CD->getClassInterface());
    break;
  }

  case Decl::ObjCProtocol:
    ObjCRuntime->GenerateProtocol(cast<ObjCProtocolDecl>(D));
    break;

  case Decl::ObjCCategoryImpl:
    // Categories have properties but don't support synthesize so we
    // can ignore them here.
    ObjCRuntime->GenerateCategory(cast<ObjCCategoryImplDecl>(D));
    break;

  case Decl::ObjCImplementation: {
    ObjCImplementationDecl *OMD = cast<ObjCImplementationDecl>(D);
    if (Features.ObjCNonFragileABI2 && OMD->hasSynthBitfield())
      Context.ResetObjCLayout(OMD->getClassInterface());
    EmitObjCPropertyImplementations(OMD);
    EmitObjCIvarInitializations(OMD);
    ObjCRuntime->GenerateClass(OMD);
    break;
  }
  case Decl::ObjCMethod: {
    ObjCMethodDecl *OMD = cast<ObjCMethodDecl>(D);
    // If this is not a prototype, emit the body.
    if (OMD->getBody())
      CodeGenFunction(*this).GenerateObjCMethod(OMD);
    break;
  }
  case Decl::ObjCCompatibleAlias:
    // compatibility-alias is a directive and has no code gen.
    break;

  case Decl::LinkageSpec:
    EmitLinkageSpec(cast<LinkageSpecDecl>(D));
    break;

  case Decl::FileScopeAsm: {
    FileScopeAsmDecl *AD = cast<FileScopeAsmDecl>(D);
    StringRef AsmString = AD->getAsmString()->getString();

    const std::string &S = getModule().getModuleInlineAsm();
    if (S.empty())
      getModule().setModuleInlineAsm(AsmString);
    else if (*--S.end() == '\n')
      getModule().setModuleInlineAsm(S + AsmString.str());
    else
      getModule().setModuleInlineAsm(S + '\n' + AsmString.str());
    break;
  }

  default:
    // Make sure we handled everything we should, every other kind is a
    // non-top-level decl.  FIXME: Would be nice to have an isTopLevelDeclKind
    // function. Need to recode Decl::Kind to do that easily.
    assert(isa<TypeDecl>(D) && "Unsupported decl kind");
  }
}

/// Turns the given pointer into a constant.
static llvm::Constant *GetPointerConstant(llvm::LLVMContext &Context,
                                          const void *Ptr) {
  uintptr_t PtrInt = reinterpret_cast<uintptr_t>(Ptr);
  llvm::Type *i64 = llvm::Type::getInt64Ty(Context);
  return llvm::ConstantInt::get(i64, PtrInt);
}

static void EmitGlobalDeclMetadata(CodeGenModule &CGM,
                                   llvm::NamedMDNode *&GlobalMetadata,
                                   GlobalDecl D,
                                   llvm::GlobalValue *Addr) {
  if (!GlobalMetadata)
    GlobalMetadata =
      CGM.getModule().getOrInsertNamedMetadata("clang.global.decl.ptrs");

  // TODO: should we report variant information for ctors/dtors?
  llvm::Value *Ops[] = {
    Addr,
    GetPointerConstant(CGM.getLLVMContext(), D.getDecl())
  };
  GlobalMetadata->addOperand(llvm::MDNode::get(CGM.getLLVMContext(), Ops));
}

/// Emits metadata nodes associating all the global values in the
/// current module with the Decls they came from.  This is useful for
/// projects using IR gen as a subroutine.
///
/// Since there's currently no way to associate an MDNode directly
/// with an llvm::GlobalValue, we create a global named metadata
/// with the name 'clang.global.decl.ptrs'.
void CodeGenModule::EmitDeclMetadata() {
  llvm::NamedMDNode *GlobalMetadata = 0;

  // StaticLocalDeclMap
  for (llvm::DenseMap<GlobalDecl,StringRef>::iterator
         I = MangledDeclNames.begin(), E = MangledDeclNames.end();
       I != E; ++I) {
    llvm::GlobalValue *Addr = getModule().getNamedValue(I->second);
    EmitGlobalDeclMetadata(*this, GlobalMetadata, I->first, Addr);
  }
}

/// Emits metadata nodes for all the local variables in the current
/// function.
void CodeGenFunction::EmitDeclMetadata() {
  if (LocalDeclMap.empty()) return;

  llvm::LLVMContext &Context = getLLVMContext();

  // Find the unique metadata ID for this name.
  unsigned DeclPtrKind = Context.getMDKindID("clang.decl.ptr");

  llvm::NamedMDNode *GlobalMetadata = 0;

  for (llvm::DenseMap<const Decl*, llvm::Value*>::iterator
         I = LocalDeclMap.begin(), E = LocalDeclMap.end(); I != E; ++I) {
    const Decl *D = I->first;
    llvm::Value *Addr = I->second;

    if (llvm::AllocaInst *Alloca = dyn_cast<llvm::AllocaInst>(Addr)) {
      llvm::Value *DAddr = GetPointerConstant(getLLVMContext(), D);
      Alloca->setMetadata(DeclPtrKind, llvm::MDNode::get(Context, DAddr));
    } else if (llvm::GlobalValue *GV = dyn_cast<llvm::GlobalValue>(Addr)) {
      GlobalDecl GD = GlobalDecl(cast<VarDecl>(D));
      EmitGlobalDeclMetadata(CGM, GlobalMetadata, GD, GV);
    }
  }
}

void CodeGenModule::EmitCoverageFile() {
  if (!getCodeGenOpts().CoverageFile.empty()) {
    if (llvm::NamedMDNode *CUNode = TheModule.getNamedMetadata("llvm.dbg.cu")) {
      llvm::NamedMDNode *GCov = TheModule.getOrInsertNamedMetadata("llvm.gcov");
      llvm::LLVMContext &Ctx = TheModule.getContext();
      llvm::MDString *CoverageFile =
          llvm::MDString::get(Ctx, getCodeGenOpts().CoverageFile);
      for (int i = 0, e = CUNode->getNumOperands(); i != e; ++i) {
        llvm::MDNode *CU = CUNode->getOperand(i);
        llvm::Value *node[] = { CoverageFile, CU };
        llvm::MDNode *N = llvm::MDNode::get(Ctx, node);
        GCov->addOperand(N);
      }
    }
  }
}