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//===--- CodeGenModule.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 coordinates the per-module state used while generating code.
#include "CodeGenModule.h"
#include "CGCUDARuntime.h"
#include "CGCXXABI.h"
#include "CGCall.h"
#include "CGDebugInfo.h"
#include "CGObjCRuntime.h"
#include "CGOpenCLRuntime.h"
#include "CGOpenMPRuntime.h"
#include "CodeGenFunction.h"
#include "CodeGenPGO.h"
#include "CodeGenTBAA.h"
#include "CoverageMappingGen.h"
#include "TargetInfo.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/Mangle.h"
#include "clang/AST/RecordLayout.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/Basic/Builtins.h"
#include "clang/Basic/CharInfo.h"
#include "clang/Basic/Diagnostic.h"
#include "clang/Basic/Module.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/Basic/Version.h"
#include "clang/Frontend/CodeGenOptions.h"
#include "clang/Sema/SemaDiagnostic.h"
#include "llvm/ADT/APSInt.h"
#include "llvm/ADT/Triple.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/CallingConv.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/ProfileData/InstrProfReader.h"
#include "llvm/Support/ConvertUTF.h"
#include "llvm/Support/ErrorHandling.h"
using namespace clang;
using namespace CodeGen;
static const char AnnotationSection[] = "llvm.metadata";
static CGCXXABI *createCXXABI(CodeGenModule &CGM) {
switch (CGM.getTarget().getCXXABI().getKind()) {
case TargetCXXABI::GenericAArch64:
case TargetCXXABI::GenericARM:
case TargetCXXABI::Emscripten: // @LOCALMOD Emscripten
case TargetCXXABI::iOS:
case TargetCXXABI::iOS64:
case TargetCXXABI::GenericMIPS:
case TargetCXXABI::GenericItanium:
return CreateItaniumCXXABI(CGM);
case TargetCXXABI::Microsoft:
return CreateMicrosoftCXXABI(CGM);
llvm_unreachable("invalid C++ ABI kind");
CodeGenModule::CodeGenModule(ASTContext &C, const HeaderSearchOptions &HSO,
const PreprocessorOptions &PPO,
const CodeGenOptions &CGO, llvm::Module &M,
DiagnosticsEngine &diags,
CoverageSourceInfo *CoverageInfo)
: Context(C), LangOpts(C.getLangOpts()), HeaderSearchOpts(HSO),
PreprocessorOpts(PPO), CodeGenOpts(CGO), TheModule(M), Diags(diags),
Target(C.getTargetInfo()), ABI(createCXXABI(*this)),
VMContext(M.getContext()), TBAA(nullptr), TheTargetCodeGenInfo(nullptr),
Types(*this), VTables(*this), ObjCRuntime(nullptr),
OpenCLRuntime(nullptr), OpenMPRuntime(nullptr), CUDARuntime(nullptr),
DebugInfo(nullptr), ARCData(nullptr),
NoObjCARCExceptionsMetadata(nullptr), RRData(nullptr), PGOReader(nullptr),
CFConstantStringClassRef(nullptr), ConstantStringClassRef(nullptr),
NSConstantStringType(nullptr), NSConcreteGlobalBlock(nullptr),
NSConcreteStackBlock(nullptr), BlockObjectAssign(nullptr),
BlockObjectDispose(nullptr), BlockDescriptorType(nullptr),
GenericBlockLiteralType(nullptr), LifetimeStartFn(nullptr),
LifetimeEndFn(nullptr), SanitizerMD(new SanitizerMetadata(*this)) {
// Initialize the type cache.
llvm::LLVMContext &LLVMContext = M.getContext();
VoidTy = llvm::Type::getVoidTy(LLVMContext);
Int8Ty = llvm::Type::getInt8Ty(LLVMContext);
Int16Ty = llvm::Type::getInt16Ty(LLVMContext);
Int32Ty = llvm::Type::getInt32Ty(LLVMContext);
Int64Ty = llvm::Type::getInt64Ty(LLVMContext);
FloatTy = llvm::Type::getFloatTy(LLVMContext);
DoubleTy = llvm::Type::getDoubleTy(LLVMContext);
PointerWidthInBits = C.getTargetInfo().getPointerWidth(0);
PointerAlignInBytes =
IntTy = llvm::IntegerType::get(LLVMContext, C.getTargetInfo().getIntWidth());
IntPtrTy = llvm::IntegerType::get(LLVMContext, PointerWidthInBits);
Int8PtrTy = Int8Ty->getPointerTo(0);
Int8PtrPtrTy = Int8PtrTy->getPointerTo(0);
RuntimeCC = getTargetCodeGenInfo().getABIInfo().getRuntimeCC();
BuiltinCC = getTargetCodeGenInfo().getABIInfo().getBuiltinCC();
if (LangOpts.ObjC1)
if (LangOpts.OpenCL)
if (LangOpts.OpenMP)
if (LangOpts.CUDA)
// Enable TBAA unless it's suppressed. ThreadSanitizer needs TBAA even at O0.
if (LangOpts.Sanitize.has(SanitizerKind::Thread) ||
(!CodeGenOpts.RelaxedAliasing && CodeGenOpts.OptimizationLevel > 0))
TBAA = new CodeGenTBAA(Context, VMContext, CodeGenOpts, getLangOpts(),
// If debug info or coverage generation is enabled, create the CGDebugInfo
// object.
if (CodeGenOpts.getDebugInfo() != CodeGenOptions::NoDebugInfo ||
CodeGenOpts.EmitGcovArcs ||
DebugInfo = new CGDebugInfo(*this);
Block.GlobalUniqueCount = 0;
if (C.getLangOpts().ObjCAutoRefCount)
ARCData = new ARCEntrypoints();
RRData = new RREntrypoints();
if (!CodeGenOpts.InstrProfileInput.empty()) {
auto ReaderOrErr =
if (std::error_code EC = ReaderOrErr.getError()) {
unsigned DiagID = Diags.getCustomDiagID(DiagnosticsEngine::Error,
"Could not read profile %0: %1");
getDiags().Report(DiagID) << CodeGenOpts.InstrProfileInput
<< EC.message();
} else
PGOReader = std::move(ReaderOrErr.get());
// If coverage mapping generation is enabled, create the
// CoverageMappingModuleGen object.
if (CodeGenOpts.CoverageMapping)
CoverageMapping.reset(new CoverageMappingModuleGen(*this, *CoverageInfo));
CodeGenModule::~CodeGenModule() {
delete ObjCRuntime;
delete OpenCLRuntime;
delete OpenMPRuntime;
delete CUDARuntime;
delete TheTargetCodeGenInfo;
delete TBAA;
delete DebugInfo;
delete ARCData;
delete RRData;
void CodeGenModule::createObjCRuntime() {
// This is just isGNUFamily(), but we want to force implementors of
// new ABIs to decide how best to do this.
switch (LangOpts.ObjCRuntime.getKind()) {
case ObjCRuntime::GNUstep:
case ObjCRuntime::GCC:
case ObjCRuntime::ObjFW:
ObjCRuntime = CreateGNUObjCRuntime(*this);
case ObjCRuntime::FragileMacOSX:
case ObjCRuntime::MacOSX:
case ObjCRuntime::iOS:
ObjCRuntime = CreateMacObjCRuntime(*this);
llvm_unreachable("bad runtime kind");
void CodeGenModule::createOpenCLRuntime() {
OpenCLRuntime = new CGOpenCLRuntime(*this);
void CodeGenModule::createOpenMPRuntime() {
OpenMPRuntime = new CGOpenMPRuntime(*this);
void CodeGenModule::createCUDARuntime() {
CUDARuntime = CreateNVCUDARuntime(*this);
void CodeGenModule::addReplacement(StringRef Name, llvm::Constant *C) {
Replacements[Name] = C;
void CodeGenModule::applyReplacements() {
for (auto &I : Replacements) {
StringRef MangledName = I.first();
llvm::Constant *Replacement = I.second;
llvm::GlobalValue *Entry = GetGlobalValue(MangledName);
if (!Entry)
auto *OldF = cast<llvm::Function>(Entry);
auto *NewF = dyn_cast<llvm::Function>(Replacement);
if (!NewF) {
if (auto *Alias = dyn_cast<llvm::GlobalAlias>(Replacement)) {
NewF = dyn_cast<llvm::Function>(Alias->getAliasee());
} else {
auto *CE = cast<llvm::ConstantExpr>(Replacement);
assert(CE->getOpcode() == llvm::Instruction::BitCast ||
CE->getOpcode() == llvm::Instruction::GetElementPtr);
NewF = dyn_cast<llvm::Function>(CE->getOperand(0));
// Replace old with new, but keep the old order.
if (NewF) {
OldF->getParent()->getFunctionList().insertAfter(OldF, NewF);
// This is only used in aliases that we created and we know they have a
// linear structure.
static const llvm::GlobalObject *getAliasedGlobal(const llvm::GlobalAlias &GA) {
llvm::SmallPtrSet<const llvm::GlobalAlias*, 4> Visited;
const llvm::Constant *C = &GA;
for (;;) {
C = C->stripPointerCasts();
if (auto *GO = dyn_cast<llvm::GlobalObject>(C))
return GO;
// stripPointerCasts will not walk over weak aliases.
auto *GA2 = dyn_cast<llvm::GlobalAlias>(C);
if (!GA2)
return nullptr;
if (!Visited.insert(GA2).second)
return nullptr;
C = GA2->getAliasee();
void CodeGenModule::checkAliases() {
// Check if the constructed aliases are well formed. It is really unfortunate
// that we have to do this in CodeGen, but we only construct mangled names
// and aliases during codegen.
bool Error = false;
DiagnosticsEngine &Diags = getDiags();
for (const GlobalDecl &GD : Aliases) {
const auto *D = cast<ValueDecl>(GD.getDecl());
const AliasAttr *AA = D->getAttr<AliasAttr>();
StringRef MangledName = getMangledName(GD);
llvm::GlobalValue *Entry = GetGlobalValue(MangledName);
auto *Alias = cast<llvm::GlobalAlias>(Entry);
const llvm::GlobalValue *GV = getAliasedGlobal(*Alias);
if (!GV) {
Error = true;
Diags.Report(AA->getLocation(), diag::err_cyclic_alias);
} else if (GV->isDeclaration()) {
Error = true;
Diags.Report(AA->getLocation(), diag::err_alias_to_undefined);
llvm::Constant *Aliasee = Alias->getAliasee();
llvm::GlobalValue *AliaseeGV;
if (auto CE = dyn_cast<llvm::ConstantExpr>(Aliasee))
AliaseeGV = cast<llvm::GlobalValue>(CE->getOperand(0));
AliaseeGV = cast<llvm::GlobalValue>(Aliasee);
if (const SectionAttr *SA = D->getAttr<SectionAttr>()) {
StringRef AliasSection = SA->getName();
if (AliasSection != AliaseeGV->getSection())
Diags.Report(SA->getLocation(), diag::warn_alias_with_section)
<< AliasSection;
// We have to handle alias to weak aliases in here. LLVM itself disallows
// this since the object semantics would not match the IL one. For
// compatibility with gcc we implement it by just pointing the alias
// to its aliasee's aliasee. We also warn, since the user is probably
// expecting the link to be weak.
if (auto GA = dyn_cast<llvm::GlobalAlias>(AliaseeGV)) {
if (GA->mayBeOverridden()) {
Diags.Report(AA->getLocation(), diag::warn_alias_to_weak_alias)
<< GV->getName() << GA->getName();
Aliasee = llvm::ConstantExpr::getPointerBitCastOrAddrSpaceCast(
GA->getAliasee(), Alias->getType());
if (!Error)
for (const GlobalDecl &GD : Aliases) {
StringRef MangledName = getMangledName(GD);
llvm::GlobalValue *Entry = GetGlobalValue(MangledName);
auto *Alias = cast<llvm::GlobalAlias>(Entry);
void CodeGenModule::clear() {
if (OpenMPRuntime)
void InstrProfStats::reportDiagnostics(DiagnosticsEngine &Diags,
StringRef MainFile) {
if (!hasDiagnostics())
if (VisitedInMainFile > 0 && VisitedInMainFile == MissingInMainFile) {
if (MainFile.empty())
MainFile = "<stdin>";
Diags.Report(diag::warn_profile_data_unprofiled) << MainFile;
} else
Diags.Report(diag::warn_profile_data_out_of_date) << Visited << Missing
<< Mismatched;
void CodeGenModule::Release() {
if (ObjCRuntime)
if (llvm::Function *ObjCInitFunction = ObjCRuntime->ModuleInitFunction())
if (Context.getLangOpts().CUDA && !Context.getLangOpts().CUDAIsDevice &&
CUDARuntime) {
if (llvm::Function *CudaCtorFunction = CUDARuntime->makeModuleCtorFunction())
if (llvm::Function *CudaDtorFunction = CUDARuntime->makeModuleDtorFunction())
if (PGOReader && PGOStats.hasDiagnostics())
PGOStats.reportDiagnostics(getDiags(), getCodeGenOpts().MainFileName);
EmitCtorList(GlobalCtors, "llvm.global_ctors");
EmitCtorList(GlobalDtors, "llvm.global_dtors");
if (CoverageMapping)
if (CodeGenOpts.Autolink &&
(Context.getLangOpts().Modules || !LinkerOptionsMetadata.empty())) {
if (CodeGenOpts.DwarfVersion)
// We actually want the latest version when there are conflicts.
// We can change from Warning to Latest if such mode is supported.
getModule().addModuleFlag(llvm::Module::Warning, "Dwarf Version",
if (DebugInfo)
// We support a single version in the linked module. The LLVM
// parser will drop debug info with a different version number
// (and warn about it, too).
getModule().addModuleFlag(llvm::Module::Warning, "Debug Info Version",
// We need to record the widths of enums and wchar_t, so that we can generate
// the correct build attributes in the ARM backend.
llvm::Triple::ArchType Arch = Context.getTargetInfo().getTriple().getArch();
if ( Arch == llvm::Triple::arm
|| Arch == llvm::Triple::armeb
|| Arch == llvm::Triple::thumb
|| Arch == llvm::Triple::thumbeb) {
// Width of wchar_t in bytes
uint64_t WCharWidth =
getModule().addModuleFlag(llvm::Module::Error, "wchar_size", WCharWidth);
// The minimum width of an enum in bytes
uint64_t EnumWidth = Context.getLangOpts().ShortEnums ? 1 : 4;
getModule().addModuleFlag(llvm::Module::Error, "min_enum_size", EnumWidth);
if (uint32_t PLevel = Context.getLangOpts().PICLevel) {
llvm::PICLevel::Level PL = llvm::PICLevel::Default;
switch (PLevel) {
case 0: break;
case 1: PL = llvm::PICLevel::Small; break;
case 2: PL = llvm::PICLevel::Large; break;
default: llvm_unreachable("Invalid PIC Level");
if (getCodeGenOpts().EmitDeclMetadata)
if (getCodeGenOpts().EmitGcovArcs || getCodeGenOpts().EmitGcovNotes)
if (DebugInfo)
void CodeGenModule::UpdateCompletedType(const TagDecl *TD) {
// Make sure that this type is translated.
llvm::MDNode *CodeGenModule::getTBAAInfo(QualType QTy) {
if (!TBAA)
return nullptr;
return TBAA->getTBAAInfo(QTy);
llvm::MDNode *CodeGenModule::getTBAAInfoForVTablePtr() {
if (!TBAA)
return nullptr;
return TBAA->getTBAAInfoForVTablePtr();
llvm::MDNode *CodeGenModule::getTBAAStructInfo(QualType QTy) {
if (!TBAA)
return nullptr;
return TBAA->getTBAAStructInfo(QTy);
llvm::MDNode *CodeGenModule::getTBAAStructTypeInfo(QualType QTy) {
if (!TBAA)
return nullptr;
return TBAA->getTBAAStructTypeInfo(QTy);
llvm::MDNode *CodeGenModule::getTBAAStructTagInfo(QualType BaseTy,
llvm::MDNode *AccessN,
uint64_t O) {
if (!TBAA)
return nullptr;
return TBAA->getTBAAStructTagInfo(BaseTy, AccessN, O);
/// Decorate the instruction with a TBAA tag. For both scalar TBAA
/// and struct-path aware TBAA, the tag has the same format:
/// base type, access type and offset.
/// When ConvertTypeToTag is true, we create a tag based on the scalar type.
void CodeGenModule::DecorateInstruction(llvm::Instruction *Inst,
llvm::MDNode *TBAAInfo,
bool ConvertTypeToTag) {
if (ConvertTypeToTag && TBAA)
Inst->setMetadata(llvm::LLVMContext::MD_tbaa, TBAAInfo);
void CodeGenModule::Error(SourceLocation loc, StringRef message) {
unsigned diagID = getDiags().getCustomDiagID(DiagnosticsEngine::Error, "%0");
getDiags().Report(Context.getFullLoc(loc), diagID) << message;
/// ErrorUnsupported - Print out an error that codegen doesn't support the
/// specified stmt yet.
void CodeGenModule::ErrorUnsupported(const Stmt *S, const char *Type) {
unsigned DiagID = getDiags().getCustomDiagID(DiagnosticsEngine::Error,
"cannot compile this %0 yet");
std::string Msg = Type;
getDiags().Report(Context.getFullLoc(S->getLocStart()), DiagID)
<< Msg << S->getSourceRange();
/// ErrorUnsupported - Print out an error that codegen doesn't support the
/// specified decl yet.
void CodeGenModule::ErrorUnsupported(const Decl *D, const char *Type) {
unsigned DiagID = getDiags().getCustomDiagID(DiagnosticsEngine::Error,
"cannot compile this %0 yet");
std::string Msg = Type;
getDiags().Report(Context.getFullLoc(D->getLocation()), DiagID) << Msg;
llvm::ConstantInt *CodeGenModule::getSize(CharUnits size) {
return llvm::ConstantInt::get(SizeTy, size.getQuantity());
void CodeGenModule::setGlobalVisibility(llvm::GlobalValue *GV,
const NamedDecl *D) const {
// Internal definitions always have default visibility.
if (GV->hasLocalLinkage()) {
// Set visibility for definitions.
LinkageInfo LV = D->getLinkageAndVisibility();
if (LV.isVisibilityExplicit() || !GV->hasAvailableExternallyLinkage())
static llvm::GlobalVariable::ThreadLocalMode GetLLVMTLSModel(StringRef S) {
return llvm::StringSwitch<llvm::GlobalVariable::ThreadLocalMode>(S)
.Case("global-dynamic", llvm::GlobalVariable::GeneralDynamicTLSModel)
.Case("local-dynamic", llvm::GlobalVariable::LocalDynamicTLSModel)
.Case("initial-exec", llvm::GlobalVariable::InitialExecTLSModel)
.Case("local-exec", llvm::GlobalVariable::LocalExecTLSModel);
static llvm::GlobalVariable::ThreadLocalMode GetLLVMTLSModel(
CodeGenOptions::TLSModel M) {
switch (M) {
case CodeGenOptions::GeneralDynamicTLSModel:
return llvm::GlobalVariable::GeneralDynamicTLSModel;
case CodeGenOptions::LocalDynamicTLSModel:
return llvm::GlobalVariable::LocalDynamicTLSModel;
case CodeGenOptions::InitialExecTLSModel:
return llvm::GlobalVariable::InitialExecTLSModel;
case CodeGenOptions::LocalExecTLSModel:
return llvm::GlobalVariable::LocalExecTLSModel;
llvm_unreachable("Invalid TLS model!");
void CodeGenModule::setTLSMode(llvm::GlobalValue *GV, const VarDecl &D) const {
assert(D.getTLSKind() && "setting TLS mode on non-TLS var!");
llvm::GlobalValue::ThreadLocalMode TLM;
TLM = GetLLVMTLSModel(CodeGenOpts.getDefaultTLSModel());
// Override the TLS model if it is explicitly specified.
if (const TLSModelAttr *Attr = D.getAttr<TLSModelAttr>()) {
TLM = GetLLVMTLSModel(Attr->getModel());
StringRef CodeGenModule::getMangledName(GlobalDecl GD) {
StringRef &FoundStr = MangledDeclNames[GD.getCanonicalDecl()];
if (!FoundStr.empty())
return FoundStr;
const auto *ND = cast<NamedDecl>(GD.getDecl());
SmallString<256> Buffer;
StringRef Str;
if (getCXXABI().getMangleContext().shouldMangleDeclName(ND)) {
llvm::raw_svector_ostream Out(Buffer);
if (const auto *D = dyn_cast<CXXConstructorDecl>(ND))
getCXXABI().getMangleContext().mangleCXXCtor(D, GD.getCtorType(), Out);
else if (const auto *D = dyn_cast<CXXDestructorDecl>(ND))
getCXXABI().getMangleContext().mangleCXXDtor(D, GD.getDtorType(), Out);
getCXXABI().getMangleContext().mangleName(ND, Out);
Str = Out.str();
} else {
IdentifierInfo *II = ND->getIdentifier();
assert(II && "Attempt to mangle unnamed decl.");
Str = II->getName();
// Keep the first result in the case of a mangling collision.
auto Result = Manglings.insert(std::make_pair(Str, GD));
return FoundStr = Result.first->first();
StringRef CodeGenModule::getBlockMangledName(GlobalDecl GD,
const BlockDecl *BD) {
MangleContext &MangleCtx = getCXXABI().getMangleContext();
const Decl *D = GD.getDecl();
SmallString<256> Buffer;
llvm::raw_svector_ostream Out(Buffer);
if (!D)
dyn_cast_or_null<VarDecl>(initializedGlobalDecl.getDecl()), Out);
else if (const auto *CD = dyn_cast<CXXConstructorDecl>(D))
MangleCtx.mangleCtorBlock(CD, GD.getCtorType(), BD, Out);
else if (const auto *DD = dyn_cast<CXXDestructorDecl>(D))
MangleCtx.mangleDtorBlock(DD, GD.getDtorType(), BD, Out);
MangleCtx.mangleBlock(cast<DeclContext>(D), BD, Out);
auto Result = Manglings.insert(std::make_pair(Out.str(), BD));
return Result.first->first();
llvm::GlobalValue *CodeGenModule::GetGlobalValue(StringRef Name) {
return getModule().getNamedValue(Name);
/// AddGlobalCtor - Add a function to the list that will be called before
/// main() runs.
void CodeGenModule::AddGlobalCtor(llvm::Function *Ctor, int Priority,
llvm::Constant *AssociatedData) {
// FIXME: Type coercion of void()* types.
GlobalCtors.push_back(Structor(Priority, Ctor, AssociatedData));
/// AddGlobalDtor - Add a function to the list that will be called
/// when the module is unloaded.
void CodeGenModule::AddGlobalDtor(llvm::Function *Dtor, int Priority) {
// FIXME: Type coercion of void()* types.
GlobalDtors.push_back(Structor(Priority, Dtor, nullptr));
void CodeGenModule::EmitCtorList(const CtorList &Fns, const char *GlobalName) {
// Ctor function type is void()*.
llvm::FunctionType* CtorFTy = llvm::FunctionType::get(VoidTy, false);
llvm::Type *CtorPFTy = llvm::PointerType::getUnqual(CtorFTy);
// Get the type of a ctor entry, { i32, void ()*, i8* }.
llvm::StructType *CtorStructTy = llvm::StructType::get(
Int32Ty, llvm::PointerType::getUnqual(CtorFTy), VoidPtrTy, nullptr);
// Construct the constructor and destructor arrays.
SmallVector<llvm::Constant *, 8> Ctors;
for (const auto &I : Fns) {
llvm::Constant *S[] = {
llvm::ConstantInt::get(Int32Ty, I.Priority, false),
llvm::ConstantExpr::getBitCast(I.Initializer, CtorPFTy),
? llvm::ConstantExpr::getBitCast(I.AssociatedData, VoidPtrTy)
: llvm::Constant::getNullValue(VoidPtrTy))};
Ctors.push_back(llvm::ConstantStruct::get(CtorStructTy, S));
if (!Ctors.empty()) {
llvm::ArrayType *AT = llvm::ArrayType::get(CtorStructTy, Ctors.size());
new llvm::GlobalVariable(TheModule, AT, false,
llvm::ConstantArray::get(AT, Ctors),
CodeGenModule::getFunctionLinkage(GlobalDecl GD) {
const auto *D = cast<FunctionDecl>(GD.getDecl());
GVALinkage Linkage = getContext().GetGVALinkageForFunction(D);
if (isa<CXXDestructorDecl>(D) &&
GD.getDtorType())) {
// Destructor variants in the Microsoft C++ ABI are always internal or
// linkonce_odr thunks emitted on an as-needed basis.
return Linkage == GVA_Internal ? llvm::GlobalValue::InternalLinkage
: llvm::GlobalValue::LinkOnceODRLinkage;
return getLLVMLinkageForDeclarator(D, Linkage, /*isConstantVariable=*/false);
void CodeGenModule::setFunctionDLLStorageClass(GlobalDecl GD, llvm::Function *F) {
const auto *FD = cast<FunctionDecl>(GD.getDecl());
if (const auto *Dtor = dyn_cast_or_null<CXXDestructorDecl>(FD)) {
if (getCXXABI().useThunkForDtorVariant(Dtor, GD.getDtorType())) {
// Don't dllexport/import destructor thunks.
if (FD->hasAttr<DLLImportAttr>())
else if (FD->hasAttr<DLLExportAttr>())
void CodeGenModule::setFunctionDefinitionAttributes(const FunctionDecl *D,
llvm::Function *F) {
setNonAliasAttributes(D, F);
void CodeGenModule::SetLLVMFunctionAttributes(const Decl *D,
const CGFunctionInfo &Info,
llvm::Function *F) {
unsigned CallingConv;
AttributeListType AttributeList;
ConstructAttributeList(Info, D, AttributeList, CallingConv, false);
F->setAttributes(llvm::AttributeSet::get(getLLVMContext(), AttributeList));
/// Determines whether the language options require us to model
/// unwind exceptions. We treat -fexceptions as mandating this
/// except under the fragile ObjC ABI with only ObjC exceptions
/// enabled. This means, for example, that C with -fexceptions
/// enables this.
static bool hasUnwindExceptions(const LangOptions &LangOpts) {
// If exceptions are completely disabled, obviously this is false.
if (!LangOpts.Exceptions) return false;
// If C++ exceptions are enabled, this is true.
if (LangOpts.CXXExceptions) return true;
// If ObjC exceptions are enabled, this depends on the ABI.
if (LangOpts.ObjCExceptions) {
return LangOpts.ObjCRuntime.hasUnwindExceptions();
return true;
void CodeGenModule::SetLLVMFunctionAttributesForDefinition(const Decl *D,
llvm::Function *F) {
llvm::AttrBuilder B;
if (CodeGenOpts.UnwindTables)
if (!hasUnwindExceptions(LangOpts))
if (D->hasAttr<NakedAttr>()) {
// Naked implies noinline: we should not be inlining such functions.
} else if (D->hasAttr<NoDuplicateAttr>()) {
} else if (D->hasAttr<NoInlineAttr>()) {
} else if (D->hasAttr<AlwaysInlineAttr>() &&
llvm::Attribute::NoInline)) {
// (noinline wins over always_inline, and we can't specify both in IR)
if (D->hasAttr<ColdAttr>()) {
if (!D->hasAttr<OptimizeNoneAttr>())
if (D->hasAttr<MinSizeAttr>())
if (LangOpts.getStackProtector() == LangOptions::SSPOn)
else if (LangOpts.getStackProtector() == LangOptions::SSPStrong)
else if (LangOpts.getStackProtector() == LangOptions::SSPReq)
F->getContext(), llvm::AttributeSet::FunctionIndex, B));
if (D->hasAttr<OptimizeNoneAttr>()) {
// OptimizeNone implies noinline; we should not be inlining such functions.
// OptimizeNone wins over OptimizeForSize, MinSize, AlwaysInline.
assert(!F->hasFnAttribute(llvm::Attribute::OptimizeForSize) &&
"OptimizeNone and OptimizeForSize on same function!");
assert(!F->hasFnAttribute(llvm::Attribute::MinSize) &&
"OptimizeNone and MinSize on same function!");
assert(!F->hasFnAttribute(llvm::Attribute::AlwaysInline) &&
"OptimizeNone and AlwaysInline on same function!");
// Attribute 'inlinehint' has no effect on 'optnone' functions.
// Explicitly remove it from the set of function attributes.
if (isa<CXXConstructorDecl>(D) || isa<CXXDestructorDecl>(D))
else if (const auto *MD = dyn_cast<CXXMethodDecl>(D))
if (MD->isVirtual())
unsigned alignment = D->getMaxAlignment() / Context.getCharWidth();
if (alignment)
// @LOCALMOD-START Emscripten
if (getTarget().getCXXABI().arePointersToMemberFunctionsAligned()) {
// C++ ABI requires 2-byte alignment for member functions.
if (F->getAlignment() < 2 && isa<CXXMethodDecl>(D))
// @LOCALMOD-END Emscripten
void CodeGenModule::SetCommonAttributes(const Decl *D,
llvm::GlobalValue *GV) {
if (const auto *ND = dyn_cast<NamedDecl>(D))
setGlobalVisibility(GV, ND);
if (D->hasAttr<UsedAttr>())
void CodeGenModule::setAliasAttributes(const Decl *D,
llvm::GlobalValue *GV) {
SetCommonAttributes(D, GV);
// Process the dllexport attribute based on whether the original definition
// (not necessarily the aliasee) was exported.
if (D->hasAttr<DLLExportAttr>())
void CodeGenModule::setNonAliasAttributes(const Decl *D,
llvm::GlobalObject *GO) {
SetCommonAttributes(D, GO);
if (const SectionAttr *SA = D->getAttr<SectionAttr>())
getTargetCodeGenInfo().setTargetAttributes(D, GO, *this);
void CodeGenModule::SetInternalFunctionAttributes(const Decl *D,
llvm::Function *F,
const CGFunctionInfo &FI) {
SetLLVMFunctionAttributes(D, FI, F);
SetLLVMFunctionAttributesForDefinition(D, F);
setNonAliasAttributes(D, F);
static void setLinkageAndVisibilityForGV(llvm::GlobalValue *GV,
const NamedDecl *ND) {
// Set linkage and visibility in case we never see a definition.
LinkageInfo LV = ND->getLinkageAndVisibility();
if (LV.getLinkage() != ExternalLinkage) {
// Don't set internal linkage on declarations.
} else {
if (ND->hasAttr<DLLImportAttr>()) {
} else if (ND->hasAttr<DLLExportAttr>()) {
} else if (ND->hasAttr<WeakAttr>() || ND->isWeakImported()) {
// "extern_weak" is overloaded in LLVM; we probably should have
// separate linkage types for this.
// Set visibility on a declaration only if it's explicit.
if (LV.isVisibilityExplicit())
void CodeGenModule::SetFunctionAttributes(GlobalDecl GD, llvm::Function *F,
bool IsIncompleteFunction,
bool IsThunk) {
if (llvm::Intrinsic::ID IID = F->getIntrinsicID()) {
// If this is an intrinsic function, set the function's attributes
// to the intrinsic's attributes.
F->setAttributes(llvm::Intrinsic::getAttributes(getLLVMContext(), IID));
const auto *FD = cast<FunctionDecl>(GD.getDecl());
if (!IsIncompleteFunction)
SetLLVMFunctionAttributes(FD, getTypes().arrangeGlobalDeclaration(GD), F);
// Add the Returned attribute for "this", except for iOS 5 and earlier
// where substantial code, including the libstdc++ dylib, was compiled with
// GCC and does not actually return "this".
if (!IsThunk && getCXXABI().HasThisReturn(GD) &&
!(getTarget().getTriple().isiOS() &&
getTarget().getTriple().isOSVersionLT(6))) {
assert(!F->arg_empty() &&
->canLosslesslyBitCastTo(F->getReturnType()) &&
"unexpected this return");
F->addAttribute(1, llvm::Attribute::Returned);
// Only a few attributes are set on declarations; these may later be
// overridden by a definition.
setLinkageAndVisibilityForGV(F, FD);
if (const SectionAttr *SA = FD->getAttr<SectionAttr>())
// A replaceable global allocation function does not act like a builtin by
// default, only if it is invoked by a new-expression or delete-expression.
if (FD->isReplaceableGlobalAllocationFunction())
void CodeGenModule::addUsedGlobal(llvm::GlobalValue *GV) {
assert(!GV->isDeclaration() &&
"Only globals with definition can force usage.");
void CodeGenModule::addCompilerUsedGlobal(llvm::GlobalValue *GV) {
assert(!GV->isDeclaration() &&
"Only globals with definition can force usage.");
static void emitUsed(CodeGenModule &CGM, StringRef Name,
std::vector<llvm::WeakVH> &List) {
// Don't create llvm.used if there is no need.
if (List.empty())
// Convert List to what ConstantArray needs.
SmallVector<llvm::Constant*, 8> UsedArray;
for (unsigned i = 0, e = List.size(); i != e; ++i) {
UsedArray[i] =
cast<llvm::Constant>(&*List[i]), CGM.Int8PtrTy);
if (UsedArray.empty())
llvm::ArrayType *ATy = llvm::ArrayType::get(CGM.Int8PtrTy, UsedArray.size());
auto *GV = new llvm::GlobalVariable(
CGM.getModule(), ATy, false, llvm::GlobalValue::AppendingLinkage,
llvm::ConstantArray::get(ATy, UsedArray), Name);
void CodeGenModule::emitLLVMUsed() {
emitUsed(*this, "llvm.used", LLVMUsed);
emitUsed(*this, "llvm.compiler.used", LLVMCompilerUsed);
void CodeGenModule::AppendLinkerOptions(StringRef Opts) {
auto *MDOpts = llvm::MDString::get(getLLVMContext(), Opts);
LinkerOptionsMetadata.push_back(llvm::MDNode::get(getLLVMContext(), MDOpts));
void CodeGenModule::AddDetectMismatch(StringRef Name, StringRef Value) {
llvm::SmallString<32> Opt;
getTargetCodeGenInfo().getDetectMismatchOption(Name, Value, Opt);
auto *MDOpts = llvm::MDString::get(getLLVMContext(), Opt);
LinkerOptionsMetadata.push_back(llvm::MDNode::get(getLLVMContext(), MDOpts));
void CodeGenModule::AddDependentLib(StringRef Lib) {
llvm::SmallString<24> Opt;
getTargetCodeGenInfo().getDependentLibraryOption(Lib, Opt);
auto *MDOpts = llvm::MDString::get(getLLVMContext(), Opt);
LinkerOptionsMetadata.push_back(llvm::MDNode::get(getLLVMContext(), MDOpts));
/// \brief Add link options implied by the given module, including modules
/// it depends on, using a postorder walk.
static void addLinkOptionsPostorder(CodeGenModule &CGM, Module *Mod,
SmallVectorImpl<llvm::Metadata *> &Metadata,
llvm::SmallPtrSet<Module *, 16> &Visited) {
// Import this module's parent.
if (Mod->Parent && Visited.insert(Mod->Parent).second) {
addLinkOptionsPostorder(CGM, Mod->Parent, Metadata, Visited);
// Import this module's dependencies.
for (unsigned I = Mod->Imports.size(); I > 0; --I) {
if (Visited.insert(Mod->Imports[I - 1]).second)
addLinkOptionsPostorder(CGM, Mod->Imports[I-1], Metadata, Visited);
// Add linker options to link against the libraries/frameworks
// described by this module.
llvm::LLVMContext &Context = CGM.getLLVMContext();
for (unsigned I = Mod->LinkLibraries.size(); I > 0; --I) {
// Link against a framework. Frameworks are currently Darwin only, so we
// don't to ask TargetCodeGenInfo for the spelling of the linker option.
if (Mod->LinkLibraries[I-1].IsFramework) {
llvm::Metadata *Args[2] = {
llvm::MDString::get(Context, "-framework"),
llvm::MDString::get(Context, Mod->LinkLibraries[I - 1].Library)};
Metadata.push_back(llvm::MDNode::get(Context, Args));
// Link against a library.
llvm::SmallString<24> Opt;
Mod->LinkLibraries[I-1].Library, Opt);
auto *OptString = llvm::MDString::get(Context, Opt);
Metadata.push_back(llvm::MDNode::get(Context, OptString));
void CodeGenModule::EmitModuleLinkOptions() {
// Collect the set of all of the modules we want to visit to emit link
// options, which is essentially the imported modules and all of their
// non-explicit child modules.
llvm::SetVector<clang::Module *> LinkModules;
llvm::SmallPtrSet<clang::Module *, 16> Visited;
SmallVector<clang::Module *, 16> Stack;
// Seed the stack with imported modules.
for (Module *M : ImportedModules)
if (Visited.insert(M).second)
// Find all of the modules to import, making a little effort to prune
// non-leaf modules.
while (!Stack.empty()) {
clang::Module *Mod = Stack.pop_back_val();
bool AnyChildren = false;
// Visit the submodules of this module.
for (clang::Module::submodule_iterator Sub = Mod->submodule_begin(),
SubEnd = Mod->submodule_end();
Sub != SubEnd; ++Sub) {
// Skip explicit children; they need to be explicitly imported to be
// linked against.
if ((*Sub)->IsExplicit)
if (Visited.insert(*Sub).second) {
AnyChildren = true;
// We didn't find any children, so add this module to the list of
// modules to link against.
if (!AnyChildren) {
// Add link options for all of the imported modules in reverse topological
// order. We don't do anything to try to order import link flags with respect
// to linker options inserted by things like #pragma comment().
SmallVector<llvm::Metadata *, 16> MetadataArgs;
for (Module *M : LinkModules)
if (Visited.insert(M).second)
addLinkOptionsPostorder(*this, M, MetadataArgs, Visited);
std::reverse(MetadataArgs.begin(), MetadataArgs.end());
LinkerOptionsMetadata.append(MetadataArgs.begin(), MetadataArgs.end());
// Add the linker options metadata flag.
getModule().addModuleFlag(llvm::Module::AppendUnique, "Linker Options",
void CodeGenModule::EmitDeferred() {
// Emit code for any potentially referenced deferred decls. Since a
// previously unused static decl may become used during the generation of code
// for a static function, iterate until no changes are made.
if (!DeferredVTables.empty()) {
// Emitting a v-table doesn't directly cause more v-tables to
// become deferred, although it can cause functions to be
// emitted that then need those v-tables.
// Stop if we're out of both deferred v-tables and deferred declarations.
if (DeferredDeclsToEmit.empty())
// Grab the list of decls to emit. If EmitGlobalDefinition schedules more
// work, it will not interfere with this.
std::vector<DeferredGlobal> CurDeclsToEmit;
for (DeferredGlobal &G : CurDeclsToEmit) {
GlobalDecl D = G.GD;
llvm::GlobalValue *GV = G.GV;
G.GV = nullptr;
assert(!GV || GV == GetGlobalValue(getMangledName(D)));
if (!GV)
GV = GetGlobalValue(getMangledName(D));
// Check to see if we've already emitted this. This is necessary
// for a couple of reasons: first, decls can end up in the
// deferred-decls queue multiple times, and second, decls can end
// up with definitions in unusual ways (e.g. by an extern inline
// function acquiring a strong function redefinition). Just
// ignore these cases.
if (GV && !GV->isDeclaration())
// Otherwise, emit the definition and move on to the next one.
EmitGlobalDefinition(D, GV);
// If we found out that we need to emit more decls, do that recursively.
// This has the advantage that the decls are emitted in a DFS and related
// ones are close together, which is convenient for testing.
if (!DeferredVTables.empty() || !DeferredDeclsToEmit.empty()) {
assert(DeferredVTables.empty() && DeferredDeclsToEmit.empty());
void CodeGenModule::EmitGlobalAnnotations() {
if (Annotations.empty())
// Create a new global variable for the ConstantStruct in the Module.
llvm::Constant *Array = llvm::ConstantArray::get(llvm::ArrayType::get(
Annotations[0]->getType(), Annotations.size()), Annotations);
auto *gv = new llvm::GlobalVariable(getModule(), Array->getType(), false,
Array, "");
llvm::Constant *CodeGenModule::EmitAnnotationString(StringRef Str) {
llvm::Constant *&AStr = AnnotationStrings[Str];
if (AStr)
return AStr;
// Not found yet, create a new global.
llvm::Constant *s = llvm::ConstantDataArray::getString(getLLVMContext(), Str);
auto *gv =
new llvm::GlobalVariable(getModule(), s->getType(), true,
llvm::GlobalValue::PrivateLinkage, s, ".str");
AStr = gv;
return gv;
llvm::Constant *CodeGenModule::EmitAnnotationUnit(SourceLocation Loc) {
SourceManager &SM = getContext().getSourceManager();
PresumedLoc PLoc = SM.getPresumedLoc(Loc);
if (PLoc.isValid())
return EmitAnnotationString(PLoc.getFilename());
return EmitAnnotationString(SM.getBufferName(Loc));
llvm::Constant *CodeGenModule::EmitAnnotationLineNo(SourceLocation L) {
SourceManager &SM = getContext().getSourceManager();
PresumedLoc PLoc = SM.getPresumedLoc(L);
unsigned LineNo = PLoc.isValid() ? PLoc.getLine() :
return llvm::ConstantInt::get(Int32Ty, LineNo);
llvm::Constant *CodeGenModule::EmitAnnotateAttr(llvm::GlobalValue *GV,
const AnnotateAttr *AA,
SourceLocation L) {
// Get the globals for file name, annotation, and the line number.
llvm::Constant *AnnoGV = EmitAnnotationString(AA->getAnnotation()),
*UnitGV = EmitAnnotationUnit(L),
*LineNoCst = EmitAnnotationLineNo(L);
// Create the ConstantStruct for the global annotation.
llvm::Constant *Fields[4] = {
llvm::ConstantExpr::getBitCast(GV, Int8PtrTy),
llvm::ConstantExpr::getBitCast(AnnoGV, Int8PtrTy),
llvm::ConstantExpr::getBitCast(UnitGV, Int8PtrTy),
return llvm::ConstantStruct::getAnon(Fields);
void CodeGenModule::AddGlobalAnnotations(const ValueDecl *D,
llvm::GlobalValue *GV) {
assert(D->hasAttr<AnnotateAttr>() && "no annotate attribute");
// Get the struct elements for these annotations.
for (const auto *I : D->specific_attrs<AnnotateAttr>())
Annotations.push_back(EmitAnnotateAttr(GV, I, D->getLocation()));
bool CodeGenModule::isInSanitizerBlacklist(llvm::Function *Fn,
SourceLocation Loc) const {
const auto &SanitizerBL = getContext().getSanitizerBlacklist();
// Blacklist by function name.
if (SanitizerBL.isBlacklistedFunction(Fn->getName()))
return true;
// Blacklist by location.
if (!Loc.isInvalid())
return SanitizerBL.isBlacklistedLocation(Loc);
// If location is unknown, this may be a compiler-generated function. Assume
// it's located in the main file.
auto &SM = Context.getSourceManager();
if (const auto *MainFile = SM.getFileEntryForID(SM.getMainFileID())) {
return SanitizerBL.isBlacklistedFile(MainFile->getName());
return false;
bool CodeGenModule::isInSanitizerBlacklist(llvm::GlobalVariable *GV,
SourceLocation Loc, QualType Ty,
StringRef Category) const {
// For now globals can be blacklisted only in ASan and KASan.
if (!LangOpts.Sanitize.hasOneOf(
SanitizerKind::Address | SanitizerKind::KernelAddress))
return false;
const auto &SanitizerBL = getContext().getSanitizerBlacklist();
if (SanitizerBL.isBlacklistedGlobal(GV->getName(), Category))
return true;
if (SanitizerBL.isBlacklistedLocation(Loc, Category))
return true;
// Check global type.
if (!Ty.isNull()) {
// Drill down the array types: if global variable of a fixed type is
// blacklisted, we also don't instrument arrays of them.
while (auto AT = dyn_cast<ArrayType>(Ty.getTypePtr()))
Ty = AT->getElementType();
Ty = Ty.getCanonicalType().getUnqualifiedType();
// We allow to blacklist only record types (classes, structs etc.)
if (Ty->isRecordType()) {
std::string TypeStr = Ty.getAsString(getContext().getPrintingPolicy());
if (SanitizerBL.isBlacklistedType(TypeStr, Category))
return true;
return false;
bool CodeGenModule::MustBeEmitted(const ValueDecl *Global) {
// Never defer when EmitAllDecls is specified.
if (LangOpts.EmitAllDecls)
return true;
return getContext().DeclMustBeEmitted(Global);
bool CodeGenModule::MayBeEmittedEagerly(const ValueDecl *Global) {
if (const auto *FD = dyn_cast<FunctionDecl>(Global))
if (FD->getTemplateSpecializationKind() == TSK_ImplicitInstantiation)
// Implicit template instantiations may change linkage if they are later
// explicitly instantiated, so they should not be emitted eagerly.
return false;
// If OpenMP is enabled and threadprivates must be generated like TLS, delay
// codegen for global variables, because they may be marked as threadprivate.
if (LangOpts.OpenMP && LangOpts.OpenMPUseTLS &&
getContext().getTargetInfo().isTLSSupported() && isa<VarDecl>(Global))
return false;
return true;
llvm::Constant *CodeGenModule::GetAddrOfUuidDescriptor(
const CXXUuidofExpr* E) {
// Sema has verified that IIDSource has a __declspec(uuid()), and that its
// well-formed.
StringRef Uuid = E->getUuidAsStringRef(Context);
std::string Name = "_GUID_" + Uuid.lower();
std::replace(Name.begin(), Name.end(), '-', '_');
// Look for an existing global.
if (llvm::GlobalVariable *GV = getModule().getNamedGlobal(Name))
return GV;
llvm::Constant *Init = EmitUuidofInitializer(Uuid);
assert(Init && "failed to initialize as constant");
auto *GV = new llvm::GlobalVariable(
getModule(), Init->getType(),
/*isConstant=*/true, llvm::GlobalValue::LinkOnceODRLinkage, Init, Name);
if (supportsCOMDAT())
return GV;
llvm::Constant *CodeGenModule::GetWeakRefReference(const ValueDecl *VD) {
const AliasAttr *AA = VD->getAttr<AliasAttr>();
assert(AA && "No alias?");
llvm::Type *DeclTy = getTypes().ConvertTypeForMem(VD->getType());
// See if there is already something with the target's name in the module.
llvm::GlobalValue *Entry = GetGlobalValue(AA->getAliasee());
if (Entry) {
unsigned AS = getContext().getTargetAddressSpace(VD->getType());
return llvm::ConstantExpr::getBitCast(Entry, DeclTy->getPointerTo(AS));
llvm::Constant *Aliasee;
if (isa<llvm::FunctionType>(DeclTy))
Aliasee = GetOrCreateLLVMFunction(AA->getAliasee(), DeclTy,
Aliasee = GetOrCreateLLVMGlobal(AA->getAliasee(),
auto *F = cast<llvm::GlobalValue>(Aliasee);
return Aliasee;
void CodeGenModule::EmitGlobal(GlobalDecl GD) {
const auto *Global = cast<ValueDecl>(GD.getDecl());
// Weak references don't produce any output by themselves.
if (Global->hasAttr<WeakRefAttr>())
// If this is an alias definition (which otherwise looks like a declaration)
// emit it now.
if (Global->hasAttr<AliasAttr>())
return EmitAliasDefinition(GD);
// If this is CUDA, be selective about which declarations we emit.
if (LangOpts.CUDA) {
if (LangOpts.CUDAIsDevice) {
if (!Global->hasAttr<CUDADeviceAttr>() &&
!Global->hasAttr<CUDAGlobalAttr>() &&
!Global->hasAttr<CUDAConstantAttr>() &&
} else {
if (!Global->hasAttr<CUDAHostAttr>() && (
Global->hasAttr<CUDADeviceAttr>() ||
Global->hasAttr<CUDAConstantAttr>() ||
// Ignore declarations, they will be emitted on their first use.
if (const auto *FD = dyn_cast<FunctionDecl>(Global)) {
// Forward declarations are emitted lazily on first use.
if (!FD->doesThisDeclarationHaveABody()) {
if (!FD->doesDeclarationForceExternallyVisibleDefinition())
StringRef MangledName = getMangledName(GD);
// Compute the function info and LLVM type.
const CGFunctionInfo &FI = getTypes().arrangeGlobalDeclaration(GD);
llvm::Type *Ty = getTypes().GetFunctionType(FI);
GetOrCreateLLVMFunction(MangledName, Ty, GD, /*ForVTable=*/false,
} else {
const auto *VD = cast<VarDecl>(Global);
assert(VD->isFileVarDecl() && "Cannot emit local var decl as global.");
if (VD->isThisDeclarationADefinition() != VarDecl::Definition &&
// Defer code generation to first use when possible, e.g. if this is an inline
// function. If the global must always be emitted, do it eagerly if possible
// to benefit from cache locality.
if (MustBeEmitted(Global) && MayBeEmittedEagerly(Global)) {
// Emit the definition if it can't be deferred.
// If we're deferring emission of a C++ variable with an
// initializer, remember the order in which it appeared in the file.
if (getLangOpts().CPlusPlus && isa<VarDecl>(Global) &&
cast<VarDecl>(Global)->hasInit()) {
DelayedCXXInitPosition[Global] = CXXGlobalInits.size();
StringRef MangledName = getMangledName(GD);
if (llvm::GlobalValue *GV = GetGlobalValue(MangledName)) {
// The value has already been used and should therefore be emitted.
addDeferredDeclToEmit(GV, GD);
} else if (MustBeEmitted(Global)) {
// The value must be emitted, but cannot be emitted eagerly.
addDeferredDeclToEmit(/*GV=*/nullptr, GD);
} else {
// Otherwise, remember that we saw a deferred decl with this name. The
// first use of the mangled name will cause it to move into
// DeferredDeclsToEmit.
DeferredDecls[MangledName] = GD;
namespace {
struct FunctionIsDirectlyRecursive :
public RecursiveASTVisitor<FunctionIsDirectlyRecursive> {
const StringRef Name;
const Builtin::Context &BI;
bool Result;
FunctionIsDirectlyRecursive(StringRef N, const Builtin::Context &C) :
Name(N), BI(C), Result(false) {
typedef RecursiveASTVisitor<FunctionIsDirectlyRecursive> Base;
bool TraverseCallExpr(CallExpr *E) {
const FunctionDecl *FD = E->getDirectCallee();
if (!FD)
return true;
AsmLabelAttr *Attr = FD->getAttr<AsmLabelAttr>();
if (Attr && Name == Attr->getLabel()) {
Result = true;
return false;
unsigned BuiltinID = FD->getBuiltinID();
if (!BuiltinID || !BI.isLibFunction(BuiltinID))
return true;
StringRef BuiltinName = BI.GetName(BuiltinID);
if (BuiltinName.startswith("__builtin_") &&
Name == BuiltinName.slice(strlen("__builtin_"), StringRef::npos)) {
Result = true;
return false;
return true;
// isTriviallyRecursive - Check if this function calls another
// decl that, because of the asm attribute or the other decl being a builtin,
// ends up pointing to itself.
CodeGenModule::isTriviallyRecursive(const FunctionDecl *FD) {
StringRef Name;
if (getCXXABI().getMangleContext().shouldMangleDeclName(FD)) {
// asm labels are a special kind of mangling we have to support.
AsmLabelAttr *Attr = FD->getAttr<AsmLabelAttr>();
if (!Attr)
return false;
Name = Attr->getLabel();
} else {
Name = FD->getName();
FunctionIsDirectlyRecursive Walker(Name, Context.BuiltinInfo);
return Walker.Result;
CodeGenModule::shouldEmitFunction(GlobalDecl GD) {
if (getFunctionLinkage(GD) != llvm::Function::AvailableExternallyLinkage)
return true;
const auto *F = cast<FunctionDecl>(GD.getDecl());
if (CodeGenOpts.OptimizationLevel == 0 && !F->hasAttr<AlwaysInlineAttr>())
return false;
// PR9614. Avoid cases where the source code is lying to us. An available
// externally function should have an equivalent function somewhere else,
// but a function that calls itself is clearly not equivalent to the real
// implementation.
// This happens in glibc's btowc and in some configure checks.
return !isTriviallyRecursive(F);
/// If the type for the method's class was generated by
/// CGDebugInfo::createContextChain(), the cache contains only a
/// limited DIType without any declarations. Since EmitFunctionStart()
/// needs to find the canonical declaration for each method, we need
/// to construct the complete type prior to emitting the method.
void CodeGenModule::CompleteDIClassType(const CXXMethodDecl* D) {
if (!D->isInstance())
if (CGDebugInfo *DI = getModuleDebugInfo())
if (getCodeGenOpts().getDebugInfo() >= CodeGenOptions::LimitedDebugInfo) {
const auto *ThisPtr = cast<PointerType>(D->getThisType(getContext()));
DI->getOrCreateRecordType(ThisPtr->getPointeeType(), D->getLocation());
void CodeGenModule::EmitGlobalDefinition(GlobalDecl GD, llvm::GlobalValue *GV) {
const auto *D = cast<ValueDecl>(GD.getDecl());
PrettyStackTraceDecl CrashInfo(const_cast<ValueDecl *>(D), D->getLocation(),
"Generating code for declaration");
if (isa<FunctionDecl>(D)) {
// At -O0, don't generate IR for functions with available_externally
// linkage.
if (!shouldEmitFunction(GD))
if (const auto *Method = dyn_cast<CXXMethodDecl>(D)) {
// Make sure to emit the definition(s) before we emit the thunks.
// This is necessary for the generation of certain thunks.
if (const auto *CD = dyn_cast<CXXConstructorDecl>(Method))
ABI->emitCXXStructor(CD, getFromCtorType(GD.getCtorType()));
else if (const auto *DD = dyn_cast<CXXDestructorDecl>(Method))
ABI->emitCXXStructor(DD, getFromDtorType(GD.getDtorType()));
EmitGlobalFunctionDefinition(GD, GV);
if (Method->isVirtual())
return EmitGlobalFunctionDefinition(GD, GV);
if (const auto *VD = dyn_cast<VarDecl>(D))
return EmitGlobalVarDefinition(VD);
llvm_unreachable("Invalid argument to EmitGlobalDefinition()");
/// GetOrCreateLLVMFunction - If the specified mangled name is not in the
/// module, create and return an llvm Function with the specified type. If there
/// is something in the module with the specified name, return it potentially
/// bitcasted to the right type.
/// If D is non-null, it specifies a decl that correspond to this. This is used
/// to set the attributes on the function when it is first created.
llvm::Constant *
CodeGenModule::GetOrCreateLLVMFunction(StringRef MangledName,
llvm::Type *Ty,
GlobalDecl GD, bool ForVTable,
bool DontDefer, bool IsThunk,
llvm::AttributeSet ExtraAttrs) {
const Decl *D = GD.getDecl();
// Lookup the entry, lazily creating it if necessary.
llvm::GlobalValue *Entry = GetGlobalValue(MangledName);
if (Entry) {
if (WeakRefReferences.erase(Entry)) {
const FunctionDecl *FD = cast_or_null<FunctionDecl>(D);
if (FD && !FD->hasAttr<WeakAttr>())
// Handle dropped DLL attributes.
if (D && !D->hasAttr<DLLImportAttr>() && !D->hasAttr<DLLExportAttr>())
if (Entry->getType()->getElementType() == Ty)
return Entry;
// Make sure the result is of the correct type.
return llvm::ConstantExpr::getBitCast(Entry, Ty->getPointerTo());
// This function doesn't have a complete type (for example, the return
// type is an incomplete struct). Use a fake type instead, and make
// sure not to try to set attributes.
bool IsIncompleteFunction = false;
llvm::FunctionType *FTy;
if (isa<llvm::FunctionType>(Ty)) {
FTy = cast<llvm::FunctionType>(Ty);
} else {
FTy = llvm::FunctionType::get(VoidTy, false);
IsIncompleteFunction = true;
llvm::Function *F = llvm::Function::Create(FTy,
MangledName, &getModule());
assert(F->getName() == MangledName && "name was uniqued!");
if (D)
SetFunctionAttributes(GD, F, IsIncompleteFunction, IsThunk);
if (ExtraAttrs.hasAttributes(llvm::AttributeSet::FunctionIndex)) {
llvm::AttrBuilder B(ExtraAttrs, llvm::AttributeSet::FunctionIndex);
if (!DontDefer) {
// All MSVC dtors other than the base dtor are linkonce_odr and delegate to
// each other bottoming out with the base dtor. Therefore we emit non-base
// dtors on usage, even if there is no dtor definition in the TU.
if (D && isa<CXXDestructorDecl>(D) &&
addDeferredDeclToEmit(F, GD);
// This is the first use or definition of a mangled name. If there is a
// deferred decl with this name, remember that we need to emit it at the end
// of the file.
auto DDI = DeferredDecls.find(MangledName);
if (DDI != DeferredDecls.end()) {
// Move the potentially referenced deferred decl to the
// DeferredDeclsToEmit list, and remove it from DeferredDecls (since we
// don't need it anymore).
addDeferredDeclToEmit(F, DDI->second);
// Otherwise, there are cases we have to worry about where we're
// using a declaration for which we must emit a definition but where
// we might not find a top-level definition:
// - member functions defined inline in their classes
// - friend functions defined inline in some class
// - special member functions with implicit definitions
// If we ever change our AST traversal to walk into class methods,
// this will be unnecessary.
// We also don't emit a definition for a function if it's going to be an
// entry in a vtable, unless it's already marked as used.
} else if (getLangOpts().CPlusPlus && D) {
// Look for a declaration that's lexically in a record.
for (const auto *FD = cast<FunctionDecl>(D)->getMostRecentDecl(); FD;
FD = FD->getPreviousDecl()) {
if (isa<CXXRecordDecl>(FD->getLexicalDeclContext())) {
if (FD->doesThisDeclarationHaveABody()) {
addDeferredDeclToEmit(F, GD.getWithDecl(FD));
// Make sure the result is of the requested type.
if (!IsIncompleteFunction) {
assert(F->getType()->getElementType() == Ty);
return F;
llvm::Type *PTy = llvm::PointerType::getUnqual(Ty);
return llvm::ConstantExpr::getBitCast(F, PTy);
/// GetAddrOfFunction - Return the address of the given function. If Ty is
/// non-null, then this function will use the specified type if it has to
/// create it (this occurs when we see a definition of the function).
llvm::Constant *CodeGenModule::GetAddrOfFunction(GlobalDecl GD,
llvm::Type *Ty,
bool ForVTable,
bool DontDefer) {
// If there was no specific requested type, just convert it now.
if (!Ty)
Ty = getTypes().ConvertType(cast<ValueDecl>(GD.getDecl())->getType());
StringRef MangledName = getMangledName(GD);
return GetOrCreateLLVMFunction(MangledName, Ty, GD, ForVTable, DontDefer);
/// CreateRuntimeFunction - Create a new runtime function with the specified
/// type and name.
llvm::Constant *
CodeGenModule::CreateRuntimeFunction(llvm::FunctionType *FTy,
StringRef Name,
llvm::AttributeSet ExtraAttrs) {
llvm::Constant *C =
GetOrCreateLLVMFunction(Name, FTy, GlobalDecl(), /*ForVTable=*/false,
/*DontDefer=*/false, /*IsThunk=*/false, ExtraAttrs);
if (auto *F = dyn_cast<llvm::Function>(C))
if (F->empty())
return C;
/// CreateBuiltinFunction - Create a new builtin function with the specified
/// type and name.
llvm::Constant *
CodeGenModule::CreateBuiltinFunction(llvm::FunctionType *FTy,
StringRef Name,
llvm::AttributeSet ExtraAttrs) {
llvm::Constant *C =
GetOrCreateLLVMFunction(Name, FTy, GlobalDecl(), /*ForVTable=*/false,
/*DontDefer=*/false, /*IsThunk=*/false, ExtraAttrs);
if (auto *F = dyn_cast<llvm::Function>(C))
if (F->empty())
return C;
/// isTypeConstant - Determine whether an object of this type can be emitted
/// as a constant.
/// If ExcludeCtor is true, the duration when the object's constructor runs
/// will not be considered. The caller will need to verify that the object is
/// not written to during its construction.
bool CodeGenModule::isTypeConstant(QualType Ty, bool ExcludeCtor) {
if (!Ty.isConstant(Context) && !Ty->isReferenceType())
return false;
if (Context.getLangOpts().CPlusPlus) {
if (const CXXRecordDecl *Record
= Context.getBaseElementType(Ty)->getAsCXXRecordDecl())
return ExcludeCtor && !Record->hasMutableFields() &&
return true;
/// GetOrCreateLLVMGlobal - If the specified mangled name is not in the module,
/// create and return an llvm GlobalVariable with the specified type. If there
/// is something in the module with the specified name, return it potentially
/// bitcasted to the right type.
/// If D is non-null, it specifies a decl that correspond to this. This is used
/// to set the attributes on the global when it is first created.
llvm::Constant *
CodeGenModule::GetOrCreateLLVMGlobal(StringRef MangledName,
llvm::PointerType *Ty,
const VarDecl *D) {
// Lookup the entry, lazily creating it if necessary.
llvm::GlobalValue *Entry = GetGlobalValue(MangledName);
if (Entry) {
if (WeakRefReferences.erase(Entry)) {
if (D && !D->hasAttr<WeakAttr>())
// Handle dropped DLL attributes.
if (D && !D->hasAttr<DLLImportAttr>() && !D->hasAttr<DLLExportAttr>())
if (Entry->getType() == Ty)
return Entry;
// Make sure the result is of the correct type.
if (Entry->getType()->getAddressSpace() != Ty->getAddressSpace())
return llvm::ConstantExpr::getAddrSpaceCast(Entry, Ty);
return llvm::ConstantExpr::getBitCast(Entry, Ty);
unsigned AddrSpace = GetGlobalVarAddressSpace(D, Ty->getAddressSpace());
auto *GV = new llvm::GlobalVariable(
getModule(), Ty->getElementType(), false,
llvm::GlobalValue::ExternalLinkage, nullptr, MangledName, nullptr,
llvm::GlobalVariable::NotThreadLocal, AddrSpace);
// This is the first use or definition of a mangled name. If there is a
// deferred decl with this name, remember that we need to emit it at the end
// of the file.
auto DDI = DeferredDecls.find(MangledName);
if (DDI != DeferredDecls.end()) {
// Move the potentially referenced deferred decl to the DeferredDeclsToEmit
// list, and remove it from DeferredDecls (since we don't need it anymore).
addDeferredDeclToEmit(GV, DDI->second);
// Handle things which are present even on external declarations.
if (D) {
// FIXME: This code is overly simple and should be merged with other global
// handling.
GV->setConstant(isTypeConstant(D->getType(), false));
setLinkageAndVisibilityForGV(GV, D);
if (D->getTLSKind()) {
if (D->getTLSKind() == VarDecl::TLS_Dynamic)
CXXThreadLocals.push_back(std::make_pair(D, GV));
setTLSMode(GV, *D);
// If required by the ABI, treat declarations of static data members with
// inline initializers as definitions.
if (getContext().isMSStaticDataMemberInlineDefinition(D)) {
// Handle XCore specific ABI requirements.
if (getTarget().getTriple().getArch() == llvm::Triple::xcore &&
D->getLanguageLinkage() == CLanguageLinkage &&
D->getType().isConstant(Context) &&
if (AddrSpace != Ty->getAddressSpace())
return llvm::ConstantExpr::getAddrSpaceCast(GV, Ty);
return GV;
llvm::GlobalVariable *
CodeGenModule::CreateOrReplaceCXXRuntimeVariable(StringRef Name,
llvm::Type *Ty,
llvm::GlobalValue::LinkageTypes Linkage) {
llvm::GlobalVariable *GV = getModule().getNamedGlobal(Name);
llvm::GlobalVariable *OldGV = nullptr;
if (GV) {
// Check if the variable has the right type.
if (GV->getType()->getElementType() == Ty)
return GV;
// Because C++ name mangling, the only way we can end up with an already
// existing global with the same name is if it has been declared extern "C".
assert(GV->isDeclaration() && "Declaration has wrong type!");
OldGV = GV;
// Create a new variable.
GV = new llvm::GlobalVariable(getModule(), Ty, /*isConstant=*/true,
Linkage, nullptr, Name);
if (OldGV) {
// Replace occurrences of the old variable if needed.
if (!OldGV->use_empty()) {
llvm::Constant *NewPtrForOldDecl =
llvm::ConstantExpr::getBitCast(GV, OldGV->getType());
if (supportsCOMDAT() && GV->isWeakForLinker() &&
return GV;
/// GetAddrOfGlobalVar - Return the llvm::Constant for the address of the
/// given global variable. If Ty is non-null and if the global doesn't exist,
/// then it will be created with the specified type instead of whatever the
/// normal requested type would be.
llvm::Constant *CodeGenModule::GetAddrOfGlobalVar(const VarDecl *D,
llvm::Type *Ty) {
assert(D->hasGlobalStorage() && "Not a global variable");
QualType ASTTy = D->getType();
if (!Ty)
Ty = getTypes().ConvertTypeForMem(ASTTy);
llvm::PointerType *PTy =
llvm::PointerType::get(Ty, getContext().getTargetAddressSpace(ASTTy));
StringRef MangledName = getMangledName(D);
return GetOrCreateLLVMGlobal(MangledName, PTy, D);
/// CreateRuntimeVariable - Create a new runtime global variable with the
/// specified type and name.
llvm::Constant *
CodeGenModule::CreateRuntimeVariable(llvm::Type *Ty,
StringRef Name) {
return GetOrCreateLLVMGlobal(Name, llvm::PointerType::getUnqual(Ty), nullptr);
void CodeGenModule::EmitTentativeDefinition(const VarDecl *D) {
assert(!D->getInit() && "Cannot emit definite definitions here!");
if (!MustBeEmitted(D)) {
// If we have not seen a reference to this variable yet, place it
// into the deferred declarations table to be emitted if needed
// later.
StringRef MangledName = getMangledName(D);
if (!GetGlobalValue(MangledName)) {
DeferredDecls[MangledName] = D;
// The tentative definition is the only definition.
CharUnits CodeGenModule::GetTargetTypeStoreSize(llvm::Type *Ty) const {
return Context.toCharUnitsFromBits(
unsigned CodeGenModule::GetGlobalVarAddressSpace(const VarDecl *D,
unsigned AddrSpace) {
if (LangOpts.CUDA && LangOpts.CUDAIsDevice) {
if (D->hasAttr<CUDAConstantAttr>())
AddrSpace = getContext().getTargetAddressSpace(LangAS::cuda_constant);
else if (D->hasAttr<CUDASharedAttr>())
AddrSpace = getContext().getTargetAddressSpace(LangAS::cuda_shared);
AddrSpace = getContext().getTargetAddressSpace(LangAS::cuda_device);
return AddrSpace;
template<typename SomeDecl>
void CodeGenModule::MaybeHandleStaticInExternC(const SomeDecl *D,
llvm::GlobalValue *GV) {
if (!getLangOpts().CPlusPlus)
// Must have 'used' attribute, or else inline assembly can't rely on
// the name existing.
if (!D->template hasAttr<UsedAttr>())
// Must have internal linkage and an ordinary name.
if (!D->getIdentifier() || D->getFormalLinkage() != InternalLinkage)
// Must be in an extern "C" context. Entities declared directly within
// a record are not extern "C" even if the record is in such a context.
const SomeDecl *First = D->getFirstDecl();
if (First->getDeclContext()->isRecord() || !First->isInExternCContext())
// OK, this is an internal linkage entity inside an extern "C" linkage
// specification. Make a note of that so we can give it the "expected"
// mangled name if nothing else is using that name.
std::pair<StaticExternCMap::iterator, bool> R =
StaticExternCValues.insert(std::make_pair(D->getIdentifier(), GV));
// If we have multiple internal linkage entities with the same name
// in extern "C" regions, none of them gets that name.
if (!R.second)
R.first->second = nullptr;
static bool shouldBeInCOMDAT(CodeGenModule &CGM, const Decl &D) {
if (!CGM.supportsCOMDAT())
return false;
if (D.hasAttr<SelectAnyAttr>())
return true;
GVALinkage Linkage;
if (auto *VD = dyn_cast<VarDecl>(&D))
Linkage = CGM.getContext().GetGVALinkageForVariable(VD);
Linkage = CGM.getContext().GetGVALinkageForFunction(cast<FunctionDecl>(&D));
switch (Linkage) {
case GVA_Internal:
case GVA_AvailableExternally:
case GVA_StrongExternal:
return false;
case GVA_DiscardableODR:
case GVA_StrongODR:
return true;
llvm_unreachable("No such linkage");
void CodeGenModule::maybeSetTrivialComdat(const Decl &D,
llvm::GlobalObject &GO) {
if (!shouldBeInCOMDAT(*this, D))
void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D) {
llvm::Constant *Init = nullptr;
QualType ASTTy = D->getType();
CXXRecordDecl *RD = ASTTy->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
bool NeedsGlobalCtor = false;
bool NeedsGlobalDtor = RD && !RD->hasTrivialDestructor();
const VarDecl *InitDecl;
const Expr *InitExpr = D->getAnyInitializer(InitDecl);
if (!InitExpr) {
// This is a tentative definition; tentative definitions are
// implicitly initialized with { 0 }.
// Note that tentative definitions are only emitted at the end of
// a translation unit, so they should never have incomplete
// type. In addition, EmitTentativeDefinition makes sure that we
// never attempt to emit a tentative definition if a real one
// exists. A use may still exists, however, so we still may need
// to do a RAUW.
assert(!ASTTy->isIncompleteType() && "Unexpected incomplete type");
Init = EmitNullConstant(D->getType());
} else {
initializedGlobalDecl = GlobalDecl(D);
Init = EmitConstantInit(*InitDecl);
if (!Init) {
QualType T = InitExpr->getType();
if (D->getType()->isReferenceType())
T = D->getType();
if (getLangOpts().CPlusPlus) {
Init = EmitNullConstant(T);
NeedsGlobalCtor = true;
} else {
ErrorUnsupported(D, "static initializer");
Init = llvm::UndefValue::get(getTypes().ConvertType(T));
} else {
// We don't need an initializer, so remove the entry for the delayed
// initializer position (just in case this entry was delayed) if we
// also don't need to register a destructor.
if (getLangOpts().CPlusPlus && !NeedsGlobalDtor)
llvm::Type* InitType = Init->getType();
llvm::Constant *Entry = GetAddrOfGlobalVar(D, InitType);
// Strip off a bitcast if we got one back.
if (auto *CE = dyn_cast<llvm::ConstantExpr>(Entry)) {
assert(CE->getOpcode() == llvm::Instruction::BitCast ||
CE->getOpcode() == llvm::Instruction::AddrSpaceCast ||
// All zero index gep.
CE->getOpcode() == llvm::Instruction::GetElementPtr);
Entry = CE->getOperand(0);
// Entry is now either a Function or GlobalVariable.
auto *GV = dyn_cast<llvm::GlobalVariable>(Entry);
// We have a definition after a declaration with the wrong type.
// We must make a new GlobalVariable* and update everything that used OldGV
// (a declaration or tentative definition) with the new GlobalVariable*
// (which will be a definition).
// This happens if there is a prototype for a global (e.g.
// "extern int x[];") and then a definition of a different type (e.g.
// "int x[10];"). This also happens when an initializer has a different type
// from the type of the global (this happens with unions).
if (!GV ||
GV->getType()->getElementType() != InitType ||
GV->getType()->getAddressSpace() !=
GetGlobalVarAddressSpace(D, getContext().getTargetAddressSpace(ASTTy))) {
// Move the old entry aside so that we'll create a new one.
// Make a new global with the correct type, this is now guaranteed to work.
GV = cast<llvm::GlobalVariable>(GetAddrOfGlobalVar(D, InitType));
// Replace all uses of the old global with the new global
llvm::Constant *NewPtrForOldDecl =
llvm::ConstantExpr::getBitCast(GV, Entry->getType());
// Erase the old global, since it is no longer used.
MaybeHandleStaticInExternC(D, GV);
if (D->hasAttr<AnnotateAttr>())
AddGlobalAnnotations(D, GV);
// If it is safe to mark the global 'constant', do so now.
GV->setConstant(!NeedsGlobalCtor && !NeedsGlobalDtor &&
isTypeConstant(D->getType(), true));
// If it is in a read-only section, mark it 'constant'.
if (const SectionAttr *SA = D->getAttr<SectionAttr>()) {
const ASTContext::SectionInfo &SI = Context.SectionInfos[SA->getName()];
if ((SI.SectionFlags & ASTContext::PSF_Write) == 0)
// Set the llvm linkage type as appropriate.
llvm::GlobalValue::LinkageTypes Linkage =
getLLVMLinkageVarDefinition(D, GV->isConstant());
// On Darwin, the backing variable for a C++11 thread_local variable always
// has internal linkage; all accesses should just be calls to the
// Itanium-specified entry point, which has the normal linkage of the
// variable.
if (!D->isStaticLocal() && D->getTLSKind() == VarDecl::TLS_Dynamic &&
Linkage = llvm::GlobalValue::InternalLinkage;
if (D->hasAttr<DLLImportAttr>())
else if (D->hasAttr<DLLExportAttr>())
if (Linkage == llvm::GlobalVariable::CommonLinkage)
// common vars aren't constant even if declared const.
setNonAliasAttributes(D, GV);
if (D->getTLSKind() && !GV->isThreadLocal()) {
if (D->getTLSKind() == VarDecl::TLS_Dynamic)
CXXThreadLocals.push_back(std::make_pair(D, GV));
setTLSMode(GV, *D);
maybeSetTrivialComdat(*D, *GV);
// Emit the initializer function if necessary.
if (NeedsGlobalCtor || NeedsGlobalDtor)
EmitCXXGlobalVarDeclInitFunc(D, GV, NeedsGlobalCtor);
SanitizerMD->reportGlobalToASan(GV, *D, NeedsGlobalCtor);
// Emit global variable debug information.
if (CGDebugInfo *DI = getModuleDebugInfo())
if (getCodeGenOpts().getDebugInfo() >= CodeGenOptions::LimitedDebugInfo)
DI->EmitGlobalVariable(GV, D);
static bool isVarDeclStrongDefinition(const ASTContext &Context,
CodeGenModule &CGM, const VarDecl *D,
bool NoCommon) {
// Don't give variables common linkage if -fno-common was specified unless it
// was overridden by a NoCommon attribute.
if ((NoCommon || D->hasAttr<NoCommonAttr>()) && !D->hasAttr<CommonAttr>())
return true;
// C11 6.9.2/2:
// A declaration of an identifier for an object that has file scope without
// an initializer, and without a storage-class specifier or with the
// storage-class specifier static, constitutes a tentative definition.
if (D->getInit() || D->hasExternalStorage())
return true;
// A variable cannot be both common and exist in a section.
if (D->hasAttr<SectionAttr>())
return true;
// Thread local vars aren't considered common linkage.
if (D->getTLSKind())
return true;
// Tentative definitions marked with WeakImportAttr are true definitions.
if (D->hasAttr<WeakImportAttr>())
return true;
// A variable cannot be both common and exist in a comdat.
if (shouldBeInCOMDAT(CGM, *D))
return true;
// Declarations with a required alignment do not have common linakge in MSVC
// mode.
if (Context.getLangOpts().MSVCCompat) {
if (D->hasAttr<AlignedAttr>())
return true;
QualType VarType = D->getType();
if (Context.isAlignmentRequired(VarType))
return true;
if (const auto *RT = VarType->getAs<RecordType>()) {
const RecordDecl *RD = RT->getDecl();
for (const FieldDecl *FD : RD->fields()) {
if (FD->isBitField())
if (FD->hasAttr<AlignedAttr>())
return true;
if (Context.isAlignmentRequired(FD->getType()))
return true;
return false;
llvm::GlobalValue::LinkageTypes CodeGenModule::getLLVMLinkageForDeclarator(
const DeclaratorDecl *D, GVALinkage Linkage, bool IsConstantVariable) {
if (Linkage == GVA_Internal)
return llvm::Function::InternalLinkage;
if (D->hasAttr<WeakAttr>()) {
if (IsConstantVariable)
return llvm::GlobalVariable::WeakODRLinkage;
return llvm::GlobalVariable::WeakAnyLinkage;
// We are guaranteed to have a strong definition somewhere else,
// so we can use available_externally linkage.
if (Linkage == GVA_AvailableExternally)
return llvm::Function::AvailableExternallyLinkage;
// Note that Apple's kernel linker doesn't support symbol
// coalescing, so we need to avoid linkonce and weak linkages there.
// Normally, this means we just map to internal, but for explicit
// instantiations we'll map to external.
// In C++, the compiler has to emit a definition in every translation unit
// that references the function. We should use linkonce_odr because
// a) if all references in this translation unit are optimized away, we
// don't need to codegen it. b) if the function persists, it needs to be
// merged with other definitions. c) C++ has the ODR, so we know the
// definition is dependable.
if (Linkage == GVA_DiscardableODR)
return !Context.getLangOpts().AppleKext ? llvm::Function::LinkOnceODRLinkage
: llvm::Function::InternalLinkage;
// An explicit instantiation of a template has weak linkage, since
// explicit instantiations can occur in multiple translation units
// and must all be equivalent. However, we are not allowed to
// throw away these explicit instantiations.
if (Linkage == GVA_StrongODR)
return !Context.getLangOpts().AppleKext ? llvm::Function::WeakODRLinkage
: llvm::Function::ExternalLinkage;
// C++ doesn't have tentative definitions and thus cannot have common
// linkage.
if (!getLangOpts().CPlusPlus && isa<VarDecl>(D) &&
!isVarDeclStrongDefinition(Context, *this, cast<VarDecl>(D),
return llvm::GlobalVariable::CommonLinkage;
// selectany symbols are externally visible, so use weak instead of
// linkonce. MSVC optimizes away references to const selectany globals, so
// all definitions should be the same and ODR linkage should be used.
if (D->hasAttr<SelectAnyAttr>())
return llvm::GlobalVariable::WeakODRLinkage;
// Otherwise, we have strong external linkage.
assert(Linkage == GVA_StrongExternal);
return llvm::GlobalVariable::ExternalLinkage;
llvm::GlobalValue::LinkageTypes CodeGenModule::getLLVMLinkageVarDefinition(
const VarDecl *VD, bool IsConstant) {
GVALinkage Linkage = getContext().GetGVALinkageForVariable(VD);
return getLLVMLinkageForDeclarator(VD, Linkage, IsConstant);
/// Replace the uses of a function that was declared with a non-proto type.
/// We want to silently drop extra arguments from call sites
static void replaceUsesOfNonProtoConstant(llvm::Constant *old,
llvm::Function *newFn) {
// Fast path.
if (old->use_empty()) return;
llvm::Type *newRetTy = newFn->getReturnType();
SmallVector<llvm::Value*, 4> newArgs;
for (llvm::Value::use_iterator ui = old->use_begin(), ue = old->use_end();
ui != ue; ) {
llvm::Value::use_iterator use = ui++; // Increment before the use is erased.
llvm::User *user = use->getUser();
// Recognize and replace uses of bitcasts. Most calls to
// unprototyped functions will use bitcasts.
if (auto *bitcast = dyn_cast<llvm::ConstantExpr>(user)) {
if (bitcast->getOpcode() == llvm::Instruction::BitCast)
replaceUsesOfNonProtoConstant(bitcast, newFn);
// Recognize calls to the function.
llvm::CallSite callSite(user);
if (!callSite) continue;
if (!callSite.isCallee(&*use)) continue;
// If the return types don't match exactly, then we can't
// transform this call unless it's dead.
if (callSite->getType() != newRetTy && !callSite->use_empty())
// Get the call site's attribute list.
SmallVector<llvm::AttributeSet, 8> newAttrs;
llvm::AttributeSet oldAttrs = callSite.getAttributes();
// Collect any return attributes from the call.
if (oldAttrs.hasAttributes(llvm::AttributeSet::ReturnIndex))
// If the function was passed too few arguments, don't transform.
unsigned newNumArgs = newFn->arg_size();
if (callSite.arg_size() < newNumArgs) continue;
// If extra arguments were passed, we silently drop them.
// If any of the types mismatch, we don't transform.
unsigned argNo = 0;
bool dontTransform = false;
for (llvm::Function::arg_iterator ai = newFn->arg_begin(),
ae = newFn->arg_end(); ai != ae; ++ai, ++argNo) {
if (callSite.getArgument(argNo)->getType() != ai->getType()) {
dontTransform = true;
// Add any parameter attributes.
if (oldAttrs.hasAttributes(argNo + 1))
oldAttrs.getParamAttributes(argNo + 1)));
if (dontTransform)
if (oldAttrs.hasAttributes(llvm::AttributeSet::FunctionIndex))
// Okay, we can transform this. Create the new call instruction and copy
// over the required information.
newArgs.append(callSite.arg_begin(), callSite.arg_begin() + argNo);
llvm::CallSite newCall;
if (callSite.isCall()) {
newCall = llvm::CallInst::Create(newFn, newArgs, "",
} else {
auto *oldInvoke = cast<llvm::InvokeInst>(callSite.getInstruction());
newCall = llvm::InvokeInst::Create(newFn,
newArgs, "",
newArgs.clear(); // for the next iteration
if (!newCall->getType()->isVoidTy())
llvm::AttributeSet::get(newFn->getContext(), newAttrs));
// Finally, remove the old call, replacing any uses with the new one.
if (!callSite->use_empty())
// Copy debug location attached to CI.
if (callSite->getDebugLoc())
/// ReplaceUsesOfNonProtoTypeWithRealFunction - This function is called when we
/// implement a function with no prototype, e.g. "int foo() {}". If there are
/// existing call uses of the old function in the module, this adjusts them to
/// call the new function directly.
/// This is not just a cleanup: the always_inline pass requires direct calls to
/// functions to be able to inline them. If there is a bitcast in the way, it
/// won't inline them. Instcombine normally deletes these calls, but it isn't
/// run at -O0.
static void ReplaceUsesOfNonProtoTypeWithRealFunction(llvm::GlobalValue *Old,
llvm::Function *NewFn) {
// If we're redefining a global as a function, don't transform it.
if (!isa<llvm::Function>(Old)) return;
replaceUsesOfNonProtoConstant(Old, NewFn);
void CodeGenModule::HandleCXXStaticMemberVarInstantiation(VarDecl *VD) {
TemplateSpecializationKind TSK = VD->getTemplateSpecializationKind();
// If we have a definition, this might be a deferred decl. If the
// instantiation is explicit, make sure we emit it at the end.
if (VD->getDefinition() && TSK == TSK_ExplicitInstantiationDefinition)
void CodeGenModule::EmitGlobalFunctionDefinition(GlobalDecl GD,
llvm::GlobalValue *GV) {
const auto *D = cast<FunctionDecl>(GD.getDecl());
// Compute the function info and LLVM type.
const CGFunctionInfo &FI = getTypes().arrangeGlobalDeclaration(GD);
llvm::FunctionType *Ty = getTypes().GetFunctionType(FI);
// Get or create the prototype for the function.
if (!GV) {
llvm::Constant *C =
GetAddrOfFunction(GD, Ty, /*ForVTable=*/false, /*DontDefer*/ true);
// Strip off a bitcast if we got one back.
if (auto *CE = dyn_cast<llvm::ConstantExpr>(C)) {
assert(CE->getOpcode() == llvm::Instruction::BitCast);
GV = cast<llvm::GlobalValue>(CE->getOperand(0));
} else {
GV = cast<llvm::GlobalValue>(C);
if (!GV->isDeclaration()) {
getDiags().Report(D->getLocation(), diag::err_duplicate_mangled_name);
GlobalDecl OldGD = Manglings.lookup(GV->getName());
if (auto *Prev = OldGD.getDecl())
getDiags().Report(Prev->getLocation(), diag::note_previous_definition);
if (GV->getType()->getElementType() != Ty) {
// If the types mismatch then we have to rewrite the definition.
assert(GV->isDeclaration() && "Shouldn't replace non-declaration");
// F is the Function* for the one with the wrong type, we must make a new
// Function* and update everything that used F (a declaration) with the new
// Function* (which will be a definition).
// This happens if there is a prototype for a function
// (e.g. "int f()") and then a definition of a different type
// (e.g. "int f(int x)"). Move the old function aside so that it
// doesn't interfere with GetAddrOfFunction.
auto *NewFn = cast<llvm::Function>(GetAddrOfFunction(GD, Ty));
// This might be an implementation of a function without a
// prototype, in which case, try to do special replacement of
// calls which match the new prototype. The really key thing here
// is that we also potentially drop arguments from the call site
// so as to make a direct call, which makes the inliner happier
// and suppresses a number of optimizer warnings (!) about
// dropping arguments.
if (!GV->use_empty()) {
ReplaceUsesOfNonProtoTypeWithRealFunction(GV, NewFn);
// Replace uses of F with the Function we will endow with a body.
if (!GV->use_empty()) {
llvm::Constant *NewPtrForOldDecl =
llvm::ConstantExpr::getBitCast(NewFn, GV->getType());
// Ok, delete the old function now, which is dead.
GV = NewFn;
// We need to set linkage and visibility on the function before
// generating code for it because various parts of IR generation
// want to propagate this information down (e.g. to local static
// declarations).
auto *Fn = cast<llvm::Function>(GV);
setFunctionLinkage(GD, Fn);
setFunctionDLLStorageClass(GD, Fn);
// FIXME: this is redundant with part of setFunctionDefinitionAttributes
setGlobalVisibility(Fn, D);
MaybeHandleStaticInExternC(D, Fn);
maybeSetTrivialComdat(*D, *Fn);
CodeGenFunction(*this).GenerateCode(D, Fn, FI);
setFunctionDefinitionAttributes(D, Fn);
SetLLVMFunctionAttributesForDefinition(D, Fn);
if (const ConstructorAttr *CA = D->getAttr<ConstructorAttr>())
AddGlobalCtor(Fn, CA->getPriority());
if (const DestructorAttr *DA = D->getAttr<DestructorAttr>())
AddGlobalDtor(Fn, DA->getPriority());
if (D->hasAttr<AnnotateAttr>())
AddGlobalAnnotations(D, Fn);
void CodeGenModule::EmitAliasDefinition(GlobalDecl GD) {
const auto *D = cast<ValueDecl>(GD.getDecl());
const AliasAttr *AA = D->getAttr<AliasAttr>();
assert(AA && "Not an alias?");
StringRef MangledName = getMangledName(GD);
// If there is a definition in the module, then it wins over the alias.
// This is dubious, but allow it to be safe. Just ignore the alias.
llvm::GlobalValue *Entry = GetGlobalValue(MangledName);
if (Entry && !Entry->isDeclaration())
llvm::Type *DeclTy = getTypes().ConvertTypeForMem(D->getType());
// Create a reference to the named value. This ensures that it is emitted
// if a deferred decl.
llvm::Constant *Aliasee;
if (isa<llvm::FunctionType>(DeclTy))
Aliasee = GetOrCreateLLVMFunction(AA->getAliasee(), DeclTy, GD,
Aliasee = GetOrCreateLLVMGlobal(AA->getAliasee(),
// Create the new alias itself, but don't set a name yet.
auto *GA = llvm::GlobalAlias::create(
llvm::Function::ExternalLinkage, "", Aliasee, &getModule());
if (Entry) {
if (GA->getAliasee() == Entry) {
Diags.Report(AA->getLocation(), diag::err_cyclic_alias);
// If there is a declaration in the module, then we had an extern followed
// by the alias, as in:
// extern int test6();
// ...
// int test6() __attribute__((alias("test7")));
// Remove it and replace uses of it with the alias.
} else {
// Set attributes which are particular to an alias; this is a
// specialization of the attributes which may be set on a global
// variable/function.
if (D->hasAttr<WeakAttr>() || D->hasAttr<WeakRefAttr>() ||
D->isWeakImported()) {
if (const auto *VD = dyn_cast<VarDecl>(D))
if (VD->getTLSKind())
setTLSMode(GA, *VD);
setAliasAttributes(D, GA);
llvm::Function *CodeGenModule::getIntrinsic(unsigned IID,
ArrayRef<llvm::Type*> Tys) {
return llvm::Intrinsic::getDeclaration(&getModule(), (llvm::Intrinsic::ID)IID,
static llvm::StringMapEntry<llvm::GlobalVariable *> &
GetConstantCFStringEntry(llvm::StringMap<llvm::GlobalVariable *> &Map,
const StringLiteral *Literal, bool TargetIsLSB,
bool &IsUTF16, unsigned &StringLength) {
StringRef String = Literal->getString();
unsigned NumBytes = String.size();
// Check for simple case.
if (!Literal->containsNonAsciiOrNull()) {
StringLength = NumBytes;
return *Map.insert(std::make_pair(String, nullptr)).first;
// Otherwise, convert the UTF8 literals into a string of shorts.
IsUTF16 = true;
SmallVector<UTF16, 128> ToBuf(NumBytes + 1); // +1 for ending nulls.
const UTF8 *FromPtr = (const UTF8 *);
UTF16 *ToPtr = &ToBuf[0];
(void)ConvertUTF8toUTF16(&FromPtr, FromPtr + NumBytes,
&ToPtr, ToPtr + NumBytes,
// ConvertUTF8toUTF16 returns the length in ToPtr.
StringLength = ToPtr - &ToBuf[0];
// Add an explicit null.
*ToPtr = 0;
return *Map.insert(std::make_pair(
StringRef(reinterpret_cast<const char *>(,
(StringLength + 1) * 2),
static llvm::StringMapEntry<llvm::GlobalVariable *> &
GetConstantStringEntry(llvm::StringMap<llvm::GlobalVariable *> &Map,
const StringLiteral *Literal, unsigned &StringLength) {
StringRef String = Literal->getString();
StringLength = String.size();
return *Map.insert(std::make_pair(String, nullptr)).first;
llvm::Constant *
CodeGenModule::GetAddrOfConstantCFString(const StringLiteral *Literal) {
unsigned StringLength = 0;
bool isUTF16 = false;
llvm::StringMapEntry<llvm::GlobalVariable *> &Entry =
GetConstantCFStringEntry(CFConstantStringMap, Literal,
getDataLayout().isLittleEndian(), isUTF16,
if (auto *C = Entry.second)
return C;
llvm::Constant *Zero = llvm::Constant::getNullValue(Int32Ty);
llvm::Constant *Zeros[] = { Zero, Zero };
llvm::Value *V;
// If we don't already have it, get __CFConstantStringClassReference.
if (!CFConstantStringClassRef) {
llvm::Type *Ty = getTypes().ConvertType(getContext().IntTy);
Ty = llvm::ArrayType::get(Ty, 0);
llvm::Constant *GV = CreateRuntimeVariable(Ty,
// Decay array -> ptr
V = llvm::ConstantExpr::getGetElementPtr(Ty, GV, Zeros);
CFConstantStringClassRef = V;
V = CFConstantStringClassRef;
QualType CFTy = getContext().getCFConstantStringType();
auto *STy = cast<llvm::StructType>(getTypes().ConvertType(CFTy));
llvm::Constant *Fields[4];
// Class pointer.
Fields[0] = cast<llvm::ConstantExpr>(V);
// Flags.
llvm::Type *Ty = getTypes().ConvertType(getContext().UnsignedIntTy);
Fields[1] = isUTF16 ? llvm::ConstantInt::get(Ty, 0x07d0) :
llvm::ConstantInt::get(Ty, 0x07C8);
// String pointer.
llvm::Constant *C = nullptr;
if (isUTF16) {
ArrayRef<uint16_t> Arr = llvm::makeArrayRef<uint16_t>(
reinterpret_cast<uint16_t *>(const_cast<char *>(Entry.first().data())),
Entry.first().size() / 2);
C = llvm::ConstantDataArray::get(VMContext, Arr);
} else {
C = llvm::ConstantDataArray::getString(VMContext, Entry.first());
// Note: -fwritable-strings doesn't make the backing store strings of
// CFStrings writable. (See <rdar://problem/10657500>)
auto *GV =
new llvm::GlobalVariable(getModule(), C->getType(), /*isConstant=*/true,
llvm::GlobalValue::PrivateLinkage, C, ".str");
// Don't enforce the target's minimum global alignment, since the only use
// of the string is via this class initializer.
// FIXME: We set the section explicitly to avoid a bug in ld64 224.1. Without
// it LLVM can merge the string with a non unnamed_addr one during LTO. Doing
// that changes the section it ends in, which surprises ld64.
if (isUTF16) {
CharUnits Align = getContext().getTypeAlignInChars(getContext().ShortTy);
} else {
CharUnits Align = getContext().getTypeAlignInChars(getContext().CharTy);
// String.
Fields[2] =
llvm::ConstantExpr::getGetElementPtr(GV->getValueType(), GV, Zeros);
if (isUTF16)
// Cast the UTF16 string to the correct type.
Fields[2] = llvm::ConstantExpr::getBitCast(Fields[2], Int8PtrTy);