blob: 941671c61482469b26d23f8ebe4b78f253b612ad [file] [log] [blame]
//===--- CGDecl.cpp - Emit LLVM Code for declarations ---------------------===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// This contains code to emit Decl nodes as LLVM code.
#include "CGBlocks.h"
#include "CGCXXABI.h"
#include "CGCleanup.h"
#include "CGDebugInfo.h"
#include "CGOpenCLRuntime.h"
#include "CGOpenMPRuntime.h"
#include "CodeGenFunction.h"
#include "CodeGenModule.h"
#include "ConstantEmitter.h"
#include "PatternInit.h"
#include "TargetInfo.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Attr.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/DeclOpenMP.h"
#include "clang/Basic/CodeGenOptions.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/CodeGen/CGFunctionInfo.h"
#include "clang/Sema/Sema.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/Type.h"
using namespace clang;
using namespace CodeGen;
static_assert(clang::Sema::MaximumAlignment <= llvm::Value::MaximumAlignment,
"Clang max alignment greater than what LLVM supports?");
void CodeGenFunction::EmitDecl(const Decl &D) {
switch (D.getKind()) {
case Decl::BuiltinTemplate:
case Decl::TranslationUnit:
case Decl::ExternCContext:
case Decl::Namespace:
case Decl::UnresolvedUsingTypename:
case Decl::ClassTemplateSpecialization:
case Decl::ClassTemplatePartialSpecialization:
case Decl::VarTemplateSpecialization:
case Decl::VarTemplatePartialSpecialization:
case Decl::TemplateTypeParm:
case Decl::UnresolvedUsingValue:
case Decl::NonTypeTemplateParm:
case Decl::CXXDeductionGuide:
case Decl::CXXMethod:
case Decl::CXXConstructor:
case Decl::CXXDestructor:
case Decl::CXXConversion:
case Decl::Field:
case Decl::MSProperty:
case Decl::IndirectField:
case Decl::ObjCIvar:
case Decl::ObjCAtDefsField:
case Decl::ParmVar:
case Decl::ImplicitParam:
case Decl::ClassTemplate:
case Decl::VarTemplate:
case Decl::FunctionTemplate:
case Decl::TypeAliasTemplate:
case Decl::TemplateTemplateParm:
case Decl::ObjCMethod:
case Decl::ObjCCategory:
case Decl::ObjCProtocol:
case Decl::ObjCInterface:
case Decl::ObjCCategoryImpl:
case Decl::ObjCImplementation:
case Decl::ObjCProperty:
case Decl::ObjCCompatibleAlias:
case Decl::PragmaComment:
case Decl::PragmaDetectMismatch:
case Decl::AccessSpec:
case Decl::LinkageSpec:
case Decl::Export:
case Decl::ObjCPropertyImpl:
case Decl::FileScopeAsm:
case Decl::Friend:
case Decl::FriendTemplate:
case Decl::Block:
case Decl::Captured:
case Decl::ClassScopeFunctionSpecialization:
case Decl::UsingShadow:
case Decl::ConstructorUsingShadow:
case Decl::ObjCTypeParam:
case Decl::Binding:
case Decl::UnresolvedUsingIfExists:
llvm_unreachable("Declaration should not be in declstmts!");
case Decl::Record: // struct/union/class X;
case Decl::CXXRecord: // struct/union/class X; [C++]
if (CGDebugInfo *DI = getDebugInfo())
if (cast<RecordDecl>(D).getDefinition())
case Decl::Enum: // enum X;
if (CGDebugInfo *DI = getDebugInfo())
if (cast<EnumDecl>(D).getDefinition())
case Decl::Function: // void X();
case Decl::EnumConstant: // enum ? { X = ? }
case Decl::StaticAssert: // static_assert(X, ""); [C++0x]
case Decl::Label: // __label__ x;
case Decl::Import:
case Decl::MSGuid: // __declspec(uuid("..."))
case Decl::TemplateParamObject:
case Decl::OMPThreadPrivate:
case Decl::OMPAllocate:
case Decl::OMPCapturedExpr:
case Decl::OMPRequires:
case Decl::Empty:
case Decl::Concept:
case Decl::LifetimeExtendedTemporary:
case Decl::RequiresExprBody:
// None of these decls require codegen support.
case Decl::NamespaceAlias:
if (CGDebugInfo *DI = getDebugInfo())
case Decl::Using: // using X; [C++]
if (CGDebugInfo *DI = getDebugInfo())
case Decl::UsingEnum: // using enum X; [C++]
if (CGDebugInfo *DI = getDebugInfo())
case Decl::UsingPack:
for (auto *Using : cast<UsingPackDecl>(D).expansions())
case Decl::UsingDirective: // using namespace X; [C++]
if (CGDebugInfo *DI = getDebugInfo())
case Decl::Var:
case Decl::Decomposition: {
const VarDecl &VD = cast<VarDecl>(D);
assert(VD.isLocalVarDecl() &&
"Should not see file-scope variables inside a function!");
if (auto *DD = dyn_cast<DecompositionDecl>(&VD))
for (auto *B : DD->bindings())
if (auto *HD = B->getHoldingVar())
case Decl::OMPDeclareReduction:
return CGM.EmitOMPDeclareReduction(cast<OMPDeclareReductionDecl>(&D), this);
case Decl::OMPDeclareMapper:
return CGM.EmitOMPDeclareMapper(cast<OMPDeclareMapperDecl>(&D), this);
case Decl::Typedef: // typedef int X;
case Decl::TypeAlias: { // using X = int; [C++0x]
QualType Ty = cast<TypedefNameDecl>(D).getUnderlyingType();
if (CGDebugInfo *DI = getDebugInfo())
if (Ty->isVariablyModifiedType())
/// EmitVarDecl - This method handles emission of any variable declaration
/// inside a function, including static vars etc.
void CodeGenFunction::EmitVarDecl(const VarDecl &D) {
if (D.hasExternalStorage())
// Don't emit it now, allow it to be emitted lazily on its first use.
// Some function-scope variable does not have static storage but still
// needs to be emitted like a static variable, e.g. a function-scope
// variable in constant address space in OpenCL.
if (D.getStorageDuration() != SD_Automatic) {
// Static sampler variables translated to function calls.
if (D.getType()->isSamplerT())
llvm::GlobalValue::LinkageTypes Linkage =
CGM.getLLVMLinkageVarDefinition(&D, /*IsConstant=*/false);
// FIXME: We need to force the emission/use of a guard variable for
// some variables even if we can constant-evaluate them because
// we can't guarantee every translation unit will constant-evaluate them.
return EmitStaticVarDecl(D, Linkage);
if (D.getType().getAddressSpace() == LangAS::opencl_local)
return CGM.getOpenCLRuntime().EmitWorkGroupLocalVarDecl(*this, D);
return EmitAutoVarDecl(D);
static std::string getStaticDeclName(CodeGenModule &CGM, const VarDecl &D) {
if (CGM.getLangOpts().CPlusPlus)
return CGM.getMangledName(&D).str();
// If this isn't C++, we don't need a mangled name, just a pretty one.
assert(!D.isExternallyVisible() && "name shouldn't matter");
std::string ContextName;
const DeclContext *DC = D.getDeclContext();
if (auto *CD = dyn_cast<CapturedDecl>(DC))
DC = cast<DeclContext>(CD->getNonClosureContext());
if (const auto *FD = dyn_cast<FunctionDecl>(DC))
ContextName = std::string(CGM.getMangledName(FD));
else if (const auto *BD = dyn_cast<BlockDecl>(DC))
ContextName = std::string(CGM.getBlockMangledName(GlobalDecl(), BD));
else if (const auto *OMD = dyn_cast<ObjCMethodDecl>(DC))
ContextName = OMD->getSelector().getAsString();
llvm_unreachable("Unknown context for static var decl");
ContextName += "." + D.getNameAsString();
return ContextName;
llvm::Constant *CodeGenModule::getOrCreateStaticVarDecl(
const VarDecl &D, llvm::GlobalValue::LinkageTypes Linkage) {
// In general, we don't always emit static var decls once before we reference
// them. It is possible to reference them before emitting the function that
// contains them, and it is possible to emit the containing function multiple
// times.
if (llvm::Constant *ExistingGV = StaticLocalDeclMap[&D])
return ExistingGV;
QualType Ty = D.getType();
assert(Ty->isConstantSizeType() && "VLAs can't be static");
// Use the label if the variable is renamed with the asm-label extension.
std::string Name;
if (D.hasAttr<AsmLabelAttr>())
Name = std::string(getMangledName(&D));
Name = getStaticDeclName(*this, D);
llvm::Type *LTy = getTypes().ConvertTypeForMem(Ty);
LangAS AS = GetGlobalVarAddressSpace(&D);
unsigned TargetAS = getContext().getTargetAddressSpace(AS);
// OpenCL variables in local address space and CUDA shared
// variables cannot have an initializer.
llvm::Constant *Init = nullptr;
if (Ty.getAddressSpace() == LangAS::opencl_local ||
D.hasAttr<CUDASharedAttr>() || D.hasAttr<LoaderUninitializedAttr>())
Init = llvm::UndefValue::get(LTy);
Init = EmitNullConstant(Ty);
llvm::GlobalVariable *GV = new llvm::GlobalVariable(
getModule(), LTy, Ty.isConstant(getContext()), Linkage, Init, Name,
nullptr, llvm::GlobalVariable::NotThreadLocal, TargetAS);
if (supportsCOMDAT() && GV->isWeakForLinker())
if (D.getTLSKind())
setTLSMode(GV, D);
setGVProperties(GV, &D);
// Make sure the result is of the correct type.
LangAS ExpectedAS = Ty.getAddressSpace();
llvm::Constant *Addr = GV;
if (AS != ExpectedAS) {
Addr = getTargetCodeGenInfo().performAddrSpaceCast(
*this, GV, AS, ExpectedAS,
setStaticLocalDeclAddress(&D, Addr);
// Ensure that the static local gets initialized by making sure the parent
// function gets emitted eventually.
const Decl *DC = cast<Decl>(D.getDeclContext());
// We can't name blocks or captured statements directly, so try to emit their
// parents.
if (isa<BlockDecl>(DC) || isa<CapturedDecl>(DC)) {
DC = DC->getNonClosureContext();
// FIXME: Ensure that global blocks get emitted.
if (!DC)
return Addr;
GlobalDecl GD;
if (const auto *CD = dyn_cast<CXXConstructorDecl>(DC))
GD = GlobalDecl(CD, Ctor_Base);
else if (const auto *DD = dyn_cast<CXXDestructorDecl>(DC))
GD = GlobalDecl(DD, Dtor_Base);
else if (const auto *FD = dyn_cast<FunctionDecl>(DC))
GD = GlobalDecl(FD);
else {
// Don't do anything for Obj-C method decls or global closures. We should
// never defer them.
assert(isa<ObjCMethodDecl>(DC) && "unexpected parent code decl");
if (GD.getDecl()) {
// Disable emission of the parent function for the OpenMP device codegen.
CGOpenMPRuntime::DisableAutoDeclareTargetRAII NoDeclTarget(*this);
return Addr;
/// AddInitializerToStaticVarDecl - Add the initializer for 'D' to the
/// global variable that has already been created for it. If the initializer
/// has a different type than GV does, this may free GV and return a different
/// one. Otherwise it just returns GV.
llvm::GlobalVariable *
CodeGenFunction::AddInitializerToStaticVarDecl(const VarDecl &D,
llvm::GlobalVariable *GV) {
ConstantEmitter emitter(*this);
llvm::Constant *Init = emitter.tryEmitForInitializer(D);
// If constant emission failed, then this should be a C++ static
// initializer.
if (!Init) {
if (!getLangOpts().CPlusPlus)
CGM.ErrorUnsupported(D.getInit(), "constant l-value expression");
else if (HaveInsertPoint()) {
// Since we have a static initializer, this global variable can't
// be constant.
EmitCXXGuardedInit(D, GV, /*PerformInit*/true);
return GV;
// The initializer may differ in type from the global. Rewrite
// the global to match the initializer. (We have to do this
// because some types, like unions, can't be completely represented
// in the LLVM type system.)
if (GV->getValueType() != Init->getType()) {
llvm::GlobalVariable *OldGV = GV;
GV = new llvm::GlobalVariable(
CGM.getModule(), Init->getType(), OldGV->isConstant(),
OldGV->getLinkage(), Init, "",
/*InsertBefore*/ OldGV, OldGV->getThreadLocalMode(),
// Steal the name of the old global
// Replace all uses of the old global with the new global
llvm::Constant *NewPtrForOldDecl =
llvm::ConstantExpr::getBitCast(GV, OldGV->getType());
// Erase the old global, since it is no longer used.
GV->setConstant(CGM.isTypeConstant(D.getType(), true));
if (D.needsDestruction(getContext()) == QualType::DK_cxx_destructor &&
HaveInsertPoint()) {
// We have a constant initializer, but a nontrivial destructor. We still
// need to perform a guarded "initialization" in order to register the
// destructor.
EmitCXXGuardedInit(D, GV, /*PerformInit*/false);
return GV;
void CodeGenFunction::EmitStaticVarDecl(const VarDecl &D,
llvm::GlobalValue::LinkageTypes Linkage) {
// Check to see if we already have a global variable for this
// declaration. This can happen when double-emitting function
// bodies, e.g. with complete and base constructors.
llvm::Constant *addr = CGM.getOrCreateStaticVarDecl(D, Linkage);
CharUnits alignment = getContext().getDeclAlign(&D);
// Store into LocalDeclMap before generating initializer to handle
// circular references.
setAddrOfLocalVar(&D, Address(addr, alignment));
// We can't have a VLA here, but we can have a pointer to a VLA,
// even though that doesn't really make any sense.
// Make sure to evaluate VLA bounds now so that we have them for later.
if (D.getType()->isVariablyModifiedType())
// Save the type in case adding the initializer forces a type change.
llvm::Type *expectedType = addr->getType();
llvm::GlobalVariable *var =
// CUDA's local and local static __shared__ variables should not
// have any non-empty initializers. This is ensured by Sema.
// Whatever initializer such variable may have when it gets here is
// a no-op and should not be emitted.
bool isCudaSharedVar = getLangOpts().CUDA && getLangOpts().CUDAIsDevice &&
// If this value has an initializer, emit it.
if (D.getInit() && !isCudaSharedVar)
var = AddInitializerToStaticVarDecl(D, var);
if (D.hasAttr<AnnotateAttr>())
CGM.AddGlobalAnnotations(&D, var);
if (auto *SA = D.getAttr<PragmaClangBSSSectionAttr>())
var->addAttribute("bss-section", SA->getName());
if (auto *SA = D.getAttr<PragmaClangDataSectionAttr>())
var->addAttribute("data-section", SA->getName());
if (auto *SA = D.getAttr<PragmaClangRodataSectionAttr>())
var->addAttribute("rodata-section", SA->getName());
if (auto *SA = D.getAttr<PragmaClangRelroSectionAttr>())
var->addAttribute("relro-section", SA->getName());
if (const SectionAttr *SA = D.getAttr<SectionAttr>())
if (D.hasAttr<RetainAttr>())
else if (D.hasAttr<UsedAttr>())
// We may have to cast the constant because of the initializer
// mismatch above.
// FIXME: It is really dangerous to store this in the map; if anyone
// RAUW's the GV uses of this constant will be invalid.
llvm::Constant *castedAddr =
llvm::ConstantExpr::getPointerBitCastOrAddrSpaceCast(var, expectedType);
if (var != castedAddr)
LocalDeclMap.find(&D)->second = Address(castedAddr, alignment);
CGM.setStaticLocalDeclAddress(&D, castedAddr);
CGM.getSanitizerMetadata()->reportGlobalToASan(var, D);
// Emit global variable debug descriptor for static vars.
CGDebugInfo *DI = getDebugInfo();
if (DI && CGM.getCodeGenOpts().hasReducedDebugInfo()) {
DI->EmitGlobalVariable(var, &D);
namespace {
struct DestroyObject final : EHScopeStack::Cleanup {
DestroyObject(Address addr, QualType type,
CodeGenFunction::Destroyer *destroyer,
bool useEHCleanupForArray)
: addr(addr), type(type), destroyer(destroyer),
useEHCleanupForArray(useEHCleanupForArray) {}
Address addr;
QualType type;
CodeGenFunction::Destroyer *destroyer;
bool useEHCleanupForArray;
void Emit(CodeGenFunction &CGF, Flags flags) override {
// Don't use an EH cleanup recursively from an EH cleanup.
bool useEHCleanupForArray =
flags.isForNormalCleanup() && this->useEHCleanupForArray;
CGF.emitDestroy(addr, type, destroyer, useEHCleanupForArray);
template <class Derived>
struct DestroyNRVOVariable : EHScopeStack::Cleanup {
DestroyNRVOVariable(Address addr, QualType type, llvm::Value *NRVOFlag)
: NRVOFlag(NRVOFlag), Loc(addr), Ty(type) {}
llvm::Value *NRVOFlag;
Address Loc;
QualType Ty;
void Emit(CodeGenFunction &CGF, Flags flags) override {
// Along the exceptions path we always execute the dtor.
bool NRVO = flags.isForNormalCleanup() && NRVOFlag;
llvm::BasicBlock *SkipDtorBB = nullptr;
if (NRVO) {
// If we exited via NRVO, we skip the destructor call.
llvm::BasicBlock *RunDtorBB = CGF.createBasicBlock("nrvo.unused");
SkipDtorBB = CGF.createBasicBlock("nrvo.skipdtor");
llvm::Value *DidNRVO =
CGF.Builder.CreateFlagLoad(NRVOFlag, "nrvo.val");
CGF.Builder.CreateCondBr(DidNRVO, SkipDtorBB, RunDtorBB);
static_cast<Derived *>(this)->emitDestructorCall(CGF);
if (NRVO) CGF.EmitBlock(SkipDtorBB);
virtual ~DestroyNRVOVariable() = default;
struct DestroyNRVOVariableCXX final
: DestroyNRVOVariable<DestroyNRVOVariableCXX> {
DestroyNRVOVariableCXX(Address addr, QualType type,
const CXXDestructorDecl *Dtor, llvm::Value *NRVOFlag)
: DestroyNRVOVariable<DestroyNRVOVariableCXX>(addr, type, NRVOFlag),
Dtor(Dtor) {}
const CXXDestructorDecl *Dtor;
void emitDestructorCall(CodeGenFunction &CGF) {
CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
/*Delegating=*/false, Loc, Ty);
struct DestroyNRVOVariableC final
: DestroyNRVOVariable<DestroyNRVOVariableC> {
DestroyNRVOVariableC(Address addr, llvm::Value *NRVOFlag, QualType Ty)
: DestroyNRVOVariable<DestroyNRVOVariableC>(addr, Ty, NRVOFlag) {}
void emitDestructorCall(CodeGenFunction &CGF) {
CGF.destroyNonTrivialCStruct(CGF, Loc, Ty);
struct CallStackRestore final : EHScopeStack::Cleanup {
Address Stack;
CallStackRestore(Address Stack) : Stack(Stack) {}
bool isRedundantBeforeReturn() override { return true; }
void Emit(CodeGenFunction &CGF, Flags flags) override {
llvm::Value *V = CGF.Builder.CreateLoad(Stack);
llvm::Function *F = CGF.CGM.getIntrinsic(llvm::Intrinsic::stackrestore);
CGF.Builder.CreateCall(F, V);
struct ExtendGCLifetime final : EHScopeStack::Cleanup {
const VarDecl &Var;
ExtendGCLifetime(const VarDecl *var) : Var(*var) {}
void Emit(CodeGenFunction &CGF, Flags flags) override {
// Compute the address of the local variable, in case it's a
// byref or something.
DeclRefExpr DRE(CGF.getContext(), const_cast<VarDecl *>(&Var), false,
Var.getType(), VK_LValue, SourceLocation());
llvm::Value *value = CGF.EmitLoadOfScalar(CGF.EmitDeclRefLValue(&DRE),
struct CallCleanupFunction final : EHScopeStack::Cleanup {
llvm::Constant *CleanupFn;
const CGFunctionInfo &FnInfo;
const VarDecl &Var;
CallCleanupFunction(llvm::Constant *CleanupFn, const CGFunctionInfo *Info,
const VarDecl *Var)
: CleanupFn(CleanupFn), FnInfo(*Info), Var(*Var) {}
void Emit(CodeGenFunction &CGF, Flags flags) override {
DeclRefExpr DRE(CGF.getContext(), const_cast<VarDecl *>(&Var), false,
Var.getType(), VK_LValue, SourceLocation());
// Compute the address of the local variable, in case it's a byref
// or something.
llvm::Value *Addr = CGF.EmitDeclRefLValue(&DRE).getPointer(CGF);
// In some cases, the type of the function argument will be different from
// the type of the pointer. An example of this is
// void f(void* arg);
// __attribute__((cleanup(f))) void *g;
// To fix this we insert a bitcast here.
QualType ArgTy = FnInfo.arg_begin()->type;
llvm::Value *Arg =
CGF.Builder.CreateBitCast(Addr, CGF.ConvertType(ArgTy));
CallArgList Args;
auto Callee = CGCallee::forDirect(CleanupFn);
CGF.EmitCall(FnInfo, Callee, ReturnValueSlot(), Args);
} // end anonymous namespace
/// EmitAutoVarWithLifetime - Does the setup required for an automatic
/// variable with lifetime.
static void EmitAutoVarWithLifetime(CodeGenFunction &CGF, const VarDecl &var,
Address addr,
Qualifiers::ObjCLifetime lifetime) {
switch (lifetime) {
case Qualifiers::OCL_None:
llvm_unreachable("present but none");
case Qualifiers::OCL_ExplicitNone:
// nothing to do
case Qualifiers::OCL_Strong: {
CodeGenFunction::Destroyer *destroyer =
? CodeGenFunction::destroyARCStrongPrecise
: CodeGenFunction::destroyARCStrongImprecise);
CleanupKind cleanupKind = CGF.getARCCleanupKind();
CGF.pushDestroy(cleanupKind, addr, var.getType(), destroyer,
cleanupKind & EHCleanup);
case Qualifiers::OCL_Autoreleasing:
// nothing to do
case Qualifiers::OCL_Weak:
// __weak objects always get EH cleanups; otherwise, exceptions
// could cause really nasty crashes instead of mere leaks.
CGF.pushDestroy(NormalAndEHCleanup, addr, var.getType(),
/*useEHCleanup*/ true);
static bool isAccessedBy(const VarDecl &var, const Stmt *s) {
if (const Expr *e = dyn_cast<Expr>(s)) {
// Skip the most common kinds of expressions that make
// hierarchy-walking expensive.
s = e = e->IgnoreParenCasts();
if (const DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e))
return (ref->getDecl() == &var);
if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) {
const BlockDecl *block = be->getBlockDecl();
for (const auto &I : block->captures()) {
if (I.getVariable() == &var)
return true;
for (const Stmt *SubStmt : s->children())
// SubStmt might be null; as in missing decl or conditional of an if-stmt.
if (SubStmt && isAccessedBy(var, SubStmt))
return true;
return false;
static bool isAccessedBy(const ValueDecl *decl, const Expr *e) {
if (!decl) return false;
if (!isa<VarDecl>(decl)) return false;
const VarDecl *var = cast<VarDecl>(decl);
return isAccessedBy(*var, e);
static bool tryEmitARCCopyWeakInit(CodeGenFunction &CGF,
const LValue &destLV, const Expr *init) {
bool needsCast = false;
while (auto castExpr = dyn_cast<CastExpr>(init->IgnoreParens())) {
switch (castExpr->getCastKind()) {
// Look through casts that don't require representation changes.
case CK_NoOp:
case CK_BitCast:
case CK_BlockPointerToObjCPointerCast:
needsCast = true;
// If we find an l-value to r-value cast from a __weak variable,
// emit this operation as a copy or move.
case CK_LValueToRValue: {
const Expr *srcExpr = castExpr->getSubExpr();
if (srcExpr->getType().getObjCLifetime() != Qualifiers::OCL_Weak)
return false;
// Emit the source l-value.
LValue srcLV = CGF.EmitLValue(srcExpr);
// Handle a formal type change to avoid asserting.
auto srcAddr = srcLV.getAddress(CGF);
if (needsCast) {
srcAddr = CGF.Builder.CreateElementBitCast(
srcAddr, destLV.getAddress(CGF).getElementType());
// If it was an l-value, use objc_copyWeak.
if (srcExpr->isLValue()) {
CGF.EmitARCCopyWeak(destLV.getAddress(CGF), srcAddr);
} else {
CGF.EmitARCMoveWeak(destLV.getAddress(CGF), srcAddr);
return true;
// Stop at anything else.
return false;
init = castExpr->getSubExpr();
return false;
static void drillIntoBlockVariable(CodeGenFunction &CGF,
LValue &lvalue,
const VarDecl *var) {
lvalue.setAddress(CGF.emitBlockByrefAddress(lvalue.getAddress(CGF), var));
void CodeGenFunction::EmitNullabilityCheck(LValue LHS, llvm::Value *RHS,
SourceLocation Loc) {
if (!SanOpts.has(SanitizerKind::NullabilityAssign))
auto Nullability = LHS.getType()->getNullability(getContext());
if (!Nullability || *Nullability != NullabilityKind::NonNull)
// Check if the right hand side of the assignment is nonnull, if the left
// hand side must be nonnull.
SanitizerScope SanScope(this);
llvm::Value *IsNotNull = Builder.CreateIsNotNull(RHS);
llvm::Constant *StaticData[] = {
EmitCheckSourceLocation(Loc), EmitCheckTypeDescriptor(LHS.getType()),
llvm::ConstantInt::get(Int8Ty, 0), // The LogAlignment info is unused.
llvm::ConstantInt::get(Int8Ty, TCK_NonnullAssign)};
EmitCheck({{IsNotNull, SanitizerKind::NullabilityAssign}},
SanitizerHandler::TypeMismatch, StaticData, RHS);
void CodeGenFunction::EmitScalarInit(const Expr *init, const ValueDecl *D,
LValue lvalue, bool capturedByInit) {
Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
if (!lifetime) {
llvm::Value *value = EmitScalarExpr(init);
if (capturedByInit)
drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
EmitNullabilityCheck(lvalue, value, init->getExprLoc());
EmitStoreThroughLValue(RValue::get(value), lvalue, true);
if (const CXXDefaultInitExpr *DIE = dyn_cast<CXXDefaultInitExpr>(init))
init = DIE->getExpr();
// If we're emitting a value with lifetime, we have to do the
// initialization *before* we leave the cleanup scopes.
if (auto *EWC = dyn_cast<ExprWithCleanups>(init)) {
CodeGenFunction::RunCleanupsScope Scope(*this);
return EmitScalarInit(EWC->getSubExpr(), D, lvalue, capturedByInit);
// We have to maintain the illusion that the variable is
// zero-initialized. If the variable might be accessed in its
// initializer, zero-initialize before running the initializer, then
// actually perform the initialization with an assign.
bool accessedByInit = false;
if (lifetime != Qualifiers::OCL_ExplicitNone)
accessedByInit = (capturedByInit || isAccessedBy(D, init));
if (accessedByInit) {
LValue tempLV = lvalue;
// Drill down to the __block object if necessary.
if (capturedByInit) {
// We can use a simple GEP for this because it can't have been
// moved yet.
/*follow*/ false));
auto ty =
llvm::Value *zero = CGM.getNullPointer(ty, tempLV.getType());
// If __weak, we want to use a barrier under certain conditions.
if (lifetime == Qualifiers::OCL_Weak)
EmitARCInitWeak(tempLV.getAddress(*this), zero);
// Otherwise just do a simple store.
EmitStoreOfScalar(zero, tempLV, /* isInitialization */ true);
// Emit the initializer.
llvm::Value *value = nullptr;
switch (lifetime) {
case Qualifiers::OCL_None:
llvm_unreachable("present but none");
case Qualifiers::OCL_Strong: {
if (!D || !isa<VarDecl>(D) || !cast<VarDecl>(D)->isARCPseudoStrong()) {
value = EmitARCRetainScalarExpr(init);
// If D is pseudo-strong, treat it like __unsafe_unretained here. This means
// that we omit the retain, and causes non-autoreleased return values to be
// immediately released.
case Qualifiers::OCL_ExplicitNone:
value = EmitARCUnsafeUnretainedScalarExpr(init);
case Qualifiers::OCL_Weak: {
// If it's not accessed by the initializer, try to emit the
// initialization with a copy or move.
if (!accessedByInit && tryEmitARCCopyWeakInit(*this, lvalue, init)) {
// No way to optimize a producing initializer into this. It's not
// worth optimizing for, because the value will immediately
// disappear in the common case.
value = EmitScalarExpr(init);
if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
if (accessedByInit)
EmitARCStoreWeak(lvalue.getAddress(*this), value, /*ignored*/ true);
EmitARCInitWeak(lvalue.getAddress(*this), value);
case Qualifiers::OCL_Autoreleasing:
value = EmitARCRetainAutoreleaseScalarExpr(init);
if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
EmitNullabilityCheck(lvalue, value, init->getExprLoc());
// If the variable might have been accessed by its initializer, we
// might have to initialize with a barrier. We have to do this for
// both __weak and __strong, but __weak got filtered out above.
if (accessedByInit && lifetime == Qualifiers::OCL_Strong) {
llvm::Value *oldValue = EmitLoadOfScalar(lvalue, init->getExprLoc());
EmitStoreOfScalar(value, lvalue, /* isInitialization */ true);
EmitARCRelease(oldValue, ARCImpreciseLifetime);
EmitStoreOfScalar(value, lvalue, /* isInitialization */ true);
/// Decide whether we can emit the non-zero parts of the specified initializer
/// with equal or fewer than NumStores scalar stores.
static bool canEmitInitWithFewStoresAfterBZero(llvm::Constant *Init,
unsigned &NumStores) {
// Zero and Undef never requires any extra stores.
if (isa<llvm::ConstantAggregateZero>(Init) ||
isa<llvm::ConstantPointerNull>(Init) ||
return true;
if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
return Init->isNullValue() || NumStores--;
// See if we can emit each element.
if (isa<llvm::ConstantArray>(Init) || isa<llvm::ConstantStruct>(Init)) {
for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
if (!canEmitInitWithFewStoresAfterBZero(Elt, NumStores))
return false;
return true;
if (llvm::ConstantDataSequential *CDS =
dyn_cast<llvm::ConstantDataSequential>(Init)) {
for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
llvm::Constant *Elt = CDS->getElementAsConstant(i);
if (!canEmitInitWithFewStoresAfterBZero(Elt, NumStores))
return false;
return true;
// Anything else is hard and scary.
return false;
/// For inits that canEmitInitWithFewStoresAfterBZero returned true for, emit
/// the scalar stores that would be required.
static void emitStoresForInitAfterBZero(CodeGenModule &CGM,
llvm::Constant *Init, Address Loc,
bool isVolatile, CGBuilderTy &Builder,
bool IsAutoInit) {
assert(!Init->isNullValue() && !isa<llvm::UndefValue>(Init) &&
"called emitStoresForInitAfterBZero for zero or undef value.");
if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
isa<llvm::ConstantExpr>(Init)) {
auto *I = Builder.CreateStore(Init, Loc, isVolatile);
if (IsAutoInit)
if (llvm::ConstantDataSequential *CDS =
dyn_cast<llvm::ConstantDataSequential>(Init)) {
for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
llvm::Constant *Elt = CDS->getElementAsConstant(i);
// If necessary, get a pointer to the element and emit it.
if (!Elt->isNullValue() && !isa<llvm::UndefValue>(Elt))
CGM, Elt, Builder.CreateConstInBoundsGEP2_32(Loc, 0, i), isVolatile,
Builder, IsAutoInit);
assert((isa<llvm::ConstantStruct>(Init) || isa<llvm::ConstantArray>(Init)) &&
"Unknown value type!");
for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
// If necessary, get a pointer to the element and emit it.
if (!Elt->isNullValue() && !isa<llvm::UndefValue>(Elt))
emitStoresForInitAfterBZero(CGM, Elt,
Builder.CreateConstInBoundsGEP2_32(Loc, 0, i),
isVolatile, Builder, IsAutoInit);
/// Decide whether we should use bzero plus some stores to initialize a local
/// variable instead of using a memcpy from a constant global. It is beneficial
/// to use bzero if the global is all zeros, or mostly zeros and large.
static bool shouldUseBZeroPlusStoresToInitialize(llvm::Constant *Init,
uint64_t GlobalSize) {
// If a global is all zeros, always use a bzero.
if (isa<llvm::ConstantAggregateZero>(Init)) return true;
// If a non-zero global is <= 32 bytes, always use a memcpy. If it is large,
// do it if it will require 6 or fewer scalar stores.
// TODO: Should budget depends on the size? Avoiding a large global warrants
// plopping in more stores.
unsigned StoreBudget = 6;
uint64_t SizeLimit = 32;
return GlobalSize > SizeLimit &&
canEmitInitWithFewStoresAfterBZero(Init, StoreBudget);
/// Decide whether we should use memset to initialize a local variable instead
/// of using a memcpy from a constant global. Assumes we've already decided to
/// not user bzero.
/// FIXME We could be more clever, as we are for bzero above, and generate
/// memset followed by stores. It's unclear that's worth the effort.
static llvm::Value *shouldUseMemSetToInitialize(llvm::Constant *Init,
uint64_t GlobalSize,
const llvm::DataLayout &DL) {
uint64_t SizeLimit = 32;
if (GlobalSize <= SizeLimit)
return nullptr;
return llvm::isBytewiseValue(Init, DL);
/// Decide whether we want to split a constant structure or array store into a
/// sequence of its fields' stores. This may cost us code size and compilation
/// speed, but plays better with store optimizations.
static bool shouldSplitConstantStore(CodeGenModule &CGM,
uint64_t GlobalByteSize) {
// Don't break things that occupy more than one cacheline.
uint64_t ByteSizeLimit = 64;
if (CGM.getCodeGenOpts().OptimizationLevel == 0)
return false;
if (GlobalByteSize <= ByteSizeLimit)
return true;
return false;
enum class IsPattern { No, Yes };
/// Generate a constant filled with either a pattern or zeroes.
static llvm::Constant *patternOrZeroFor(CodeGenModule &CGM, IsPattern isPattern,
llvm::Type *Ty) {
if (isPattern == IsPattern::Yes)
return initializationPatternFor(CGM, Ty);
return llvm::Constant::getNullValue(Ty);
static llvm::Constant *constWithPadding(CodeGenModule &CGM, IsPattern isPattern,
llvm::Constant *constant);
/// Helper function for constWithPadding() to deal with padding in structures.
static llvm::Constant *constStructWithPadding(CodeGenModule &CGM,
IsPattern isPattern,
llvm::StructType *STy,
llvm::Constant *constant) {
const llvm::DataLayout &DL = CGM.getDataLayout();
const llvm::StructLayout *Layout = DL.getStructLayout(STy);
llvm::Type *Int8Ty = llvm::IntegerType::getInt8Ty(CGM.getLLVMContext());
unsigned SizeSoFar = 0;
SmallVector<llvm::Constant *, 8> Values;
bool NestedIntact = true;
for (unsigned i = 0, e = STy->getNumElements(); i != e; i++) {
unsigned CurOff = Layout->getElementOffset(i);
if (SizeSoFar < CurOff) {
auto *PadTy = llvm::ArrayType::get(Int8Ty, CurOff - SizeSoFar);
Values.push_back(patternOrZeroFor(CGM, isPattern, PadTy));
llvm::Constant *CurOp;
if (constant->isZeroValue())
CurOp = llvm::Constant::getNullValue(STy->getElementType(i));
CurOp = cast<llvm::Constant>(constant->getAggregateElement(i));
auto *NewOp = constWithPadding(CGM, isPattern, CurOp);
if (CurOp != NewOp)
NestedIntact = false;
SizeSoFar = CurOff + DL.getTypeAllocSize(CurOp->getType());
unsigned TotalSize = Layout->getSizeInBytes();
if (SizeSoFar < TotalSize) {
auto *PadTy = llvm::ArrayType::get(Int8Ty, TotalSize - SizeSoFar);
Values.push_back(patternOrZeroFor(CGM, isPattern, PadTy));
if (NestedIntact && Values.size() == STy->getNumElements())
return constant;
return llvm::ConstantStruct::getAnon(Values, STy->isPacked());
/// Replace all padding bytes in a given constant with either a pattern byte or
/// 0x00.
static llvm::Constant *constWithPadding(CodeGenModule &CGM, IsPattern isPattern,
llvm::Constant *constant) {
llvm::Type *OrigTy = constant->getType();
if (const auto STy = dyn_cast<llvm::StructType>(OrigTy))
return constStructWithPadding(CGM, isPattern, STy, constant);
if (auto *ArrayTy = dyn_cast<llvm::ArrayType>(OrigTy)) {
llvm::SmallVector<llvm::Constant *, 8> Values;
uint64_t Size = ArrayTy->getNumElements();
if (!Size)
return constant;
llvm::Type *ElemTy = ArrayTy->getElementType();
bool ZeroInitializer = constant->isNullValue();
llvm::Constant *OpValue, *PaddedOp;
if (ZeroInitializer) {
OpValue = llvm::Constant::getNullValue(ElemTy);
PaddedOp = constWithPadding(CGM, isPattern, OpValue);
for (unsigned Op = 0; Op != Size; ++Op) {
if (!ZeroInitializer) {
OpValue = constant->getAggregateElement(Op);
PaddedOp = constWithPadding(CGM, isPattern, OpValue);
auto *NewElemTy = Values[0]->getType();
if (NewElemTy == ElemTy)
return constant;
auto *NewArrayTy = llvm::ArrayType::get(NewElemTy, Size);
return llvm::ConstantArray::get(NewArrayTy, Values);
// FIXME: Add handling for tail padding in vectors. Vectors don't
// have padding between or inside elements, but the total amount of
// data can be less than the allocated size.
return constant;
Address CodeGenModule::createUnnamedGlobalFrom(const VarDecl &D,
llvm::Constant *Constant,
CharUnits Align) {
auto FunctionName = [&](const DeclContext *DC) -> std::string {
if (const auto *FD = dyn_cast<FunctionDecl>(DC)) {
if (const auto *CC = dyn_cast<CXXConstructorDecl>(FD))
return CC->getNameAsString();
if (const auto *CD = dyn_cast<CXXDestructorDecl>(FD))
return CD->getNameAsString();
return std::string(getMangledName(FD));
} else if (const auto *OM = dyn_cast<ObjCMethodDecl>(DC)) {
return OM->getNameAsString();
} else if (isa<BlockDecl>(DC)) {
return "<block>";
} else if (isa<CapturedDecl>(DC)) {
return "<captured>";
} else {
llvm_unreachable("expected a function or method");
// Form a simple per-variable cache of these values in case we find we
// want to reuse them.
llvm::GlobalVariable *&CacheEntry = InitializerConstants[&D];
if (!CacheEntry || CacheEntry->getInitializer() != Constant) {
auto *Ty = Constant->getType();
bool isConstant = true;
llvm::GlobalVariable *InsertBefore = nullptr;
unsigned AS =
std::string Name;
if (D.hasGlobalStorage())
Name = getMangledName(&D).str() + ".const";
else if (const DeclContext *DC = D.getParentFunctionOrMethod())
Name = ("__const." + FunctionName(DC) + "." + D.getName()).str();
llvm_unreachable("local variable has no parent function or method");
llvm::GlobalVariable *GV = new llvm::GlobalVariable(
getModule(), Ty, isConstant, llvm::GlobalValue::PrivateLinkage,
Constant, Name, InsertBefore, llvm::GlobalValue::NotThreadLocal, AS);
CacheEntry = GV;
} else if (CacheEntry->getAlignment() < uint64_t(Align.getQuantity())) {
return Address(CacheEntry, Align);
static Address createUnnamedGlobalForMemcpyFrom(CodeGenModule &CGM,
const VarDecl &D,
CGBuilderTy &Builder,
llvm::Constant *Constant,
CharUnits Align) {
Address SrcPtr = CGM.createUnnamedGlobalFrom(D, Constant, Align);
llvm::Type *BP = llvm::PointerType::getInt8PtrTy(CGM.getLLVMContext(),
if (SrcPtr.getType() != BP)
SrcPtr = Builder.CreateBitCast(SrcPtr, BP);
return SrcPtr;
static void emitStoresForConstant(CodeGenModule &CGM, const VarDecl &D,
Address Loc, bool isVolatile,
CGBuilderTy &Builder,
llvm::Constant *constant, bool IsAutoInit) {
auto *Ty = constant->getType();
uint64_t ConstantSize = CGM.getDataLayout().getTypeAllocSize(Ty);
if (!ConstantSize)
bool canDoSingleStore = Ty->isIntOrIntVectorTy() ||
Ty->isPtrOrPtrVectorTy() || Ty->isFPOrFPVectorTy();
if (canDoSingleStore) {
auto *I = Builder.CreateStore(constant, Loc, isVolatile);
if (IsAutoInit)
auto *SizeVal = llvm::ConstantInt::get(CGM.IntPtrTy, ConstantSize);
// If the initializer is all or mostly the same, codegen with bzero / memset
// then do a few stores afterward.
if (shouldUseBZeroPlusStoresToInitialize(constant, ConstantSize)) {
auto *I = Builder.CreateMemSet(Loc, llvm::ConstantInt::get(CGM.Int8Ty, 0),
SizeVal, isVolatile);
if (IsAutoInit)
bool valueAlreadyCorrect =
constant->isNullValue() || isa<llvm::UndefValue>(constant);
if (!valueAlreadyCorrect) {
Loc = Builder.CreateBitCast(Loc, Ty->getPointerTo(Loc.getAddressSpace()));
emitStoresForInitAfterBZero(CGM, constant, Loc, isVolatile, Builder,
// If the initializer is a repeated byte pattern, use memset.
llvm::Value *Pattern =
shouldUseMemSetToInitialize(constant, ConstantSize, CGM.getDataLayout());
if (Pattern) {
uint64_t Value = 0x00;
if (!isa<llvm::UndefValue>(Pattern)) {
const llvm::APInt &AP = cast<llvm::ConstantInt>(Pattern)->getValue();
assert(AP.getBitWidth() <= 8);
Value = AP.getLimitedValue();
auto *I = Builder.CreateMemSet(
Loc, llvm::ConstantInt::get(CGM.Int8Ty, Value), SizeVal, isVolatile);
if (IsAutoInit)
// If the initializer is small, use a handful of stores.
if (shouldSplitConstantStore(CGM, ConstantSize)) {
if (auto *STy = dyn_cast<llvm::StructType>(Ty)) {
// FIXME: handle the case when STy != Loc.getElementType().
if (STy == Loc.getElementType()) {
for (unsigned i = 0; i != constant->getNumOperands(); i++) {
Address EltPtr = Builder.CreateStructGEP(Loc, i);
CGM, D, EltPtr, isVolatile, Builder,
cast<llvm::Constant>(Builder.CreateExtractValue(constant, i)),
} else if (auto *ATy = dyn_cast<llvm::ArrayType>(Ty)) {
// FIXME: handle the case when ATy != Loc.getElementType().
if (ATy == Loc.getElementType()) {
for (unsigned i = 0; i != ATy->getNumElements(); i++) {
Address EltPtr = Builder.CreateConstArrayGEP(Loc, i);
CGM, D, EltPtr, isVolatile, Builder,
cast<llvm::Constant>(Builder.CreateExtractValue(constant, i)),
// Copy from a global.
auto *I =
CGM, D, Builder, constant, Loc.getAlignment()),
SizeVal, isVolatile);
if (IsAutoInit)
static void emitStoresForZeroInit(CodeGenModule &CGM, const VarDecl &D,
Address Loc, bool isVolatile,
CGBuilderTy &Builder) {
llvm::Type *ElTy = Loc.getElementType();
llvm::Constant *constant =
constWithPadding(CGM, IsPattern::No, llvm::Constant::getNullValue(ElTy));
emitStoresForConstant(CGM, D, Loc, isVolatile, Builder, constant,
static void emitStoresForPatternInit(CodeGenModule &CGM, const VarDecl &D,
Address Loc, bool isVolatile,
CGBuilderTy &Builder) {
llvm::Type *ElTy = Loc.getElementType();
llvm::Constant *constant = constWithPadding(
CGM, IsPattern::Yes, initializationPatternFor(CGM, ElTy));
emitStoresForConstant(CGM, D, Loc, isVolatile, Builder, constant,
static bool containsUndef(llvm::Constant *constant) {
auto *Ty = constant->getType();
if (isa<llvm::UndefValue>(constant))
return true;
if (Ty->isStructTy() || Ty->isArrayTy() || Ty->isVectorTy())
for (llvm::Use &Op : constant->operands())
if (containsUndef(cast<llvm::Constant>(Op)))
return true;
return false;
static llvm::Constant *replaceUndef(CodeGenModule &CGM, IsPattern isPattern,
llvm::Constant *constant) {
auto *Ty = constant->getType();
if (isa<llvm::UndefValue>(constant))
return patternOrZeroFor(CGM, isPattern, Ty);
if (!(Ty->isStructTy() || Ty->isArrayTy() || Ty->isVectorTy()))
return constant;
if (!containsUndef(constant))
return constant;
llvm::SmallVector<llvm::Constant *, 8> Values(constant->getNumOperands());
for (unsigned Op = 0, NumOp = constant->getNumOperands(); Op != NumOp; ++Op) {
auto *OpValue = cast<llvm::Constant>(constant->getOperand(Op));
Values[Op] = replaceUndef(CGM, isPattern, OpValue);
if (Ty->isStructTy())
return llvm::ConstantStruct::get(cast<llvm::StructType>(Ty), Values);
if (Ty->isArrayTy())
return llvm::ConstantArray::get(cast<llvm::ArrayType>(Ty), Values);
return llvm::ConstantVector::get(Values);
/// EmitAutoVarDecl - Emit code and set up an entry in LocalDeclMap for a
/// variable declaration with auto, register, or no storage class specifier.
/// These turn into simple stack objects, or GlobalValues depending on target.
void CodeGenFunction::EmitAutoVarDecl(const VarDecl &D) {
AutoVarEmission emission = EmitAutoVarAlloca(D);
/// Emit a lifetime.begin marker if some criteria are satisfied.
/// \return a pointer to the temporary size Value if a marker was emitted, null
/// otherwise
llvm::Value *CodeGenFunction::EmitLifetimeStart(llvm::TypeSize Size,
llvm::Value *Addr) {
if (!ShouldEmitLifetimeMarkers)
return nullptr;
assert(Addr->getType()->getPointerAddressSpace() ==
CGM.getDataLayout().getAllocaAddrSpace() &&
"Pointer should be in alloca address space");
llvm::Value *SizeV = llvm::ConstantInt::get(
Int64Ty, Size.isScalable() ? -1 : Size.getFixedValue());
Addr = Builder.CreateBitCast(Addr, AllocaInt8PtrTy);
llvm::CallInst *C =
Builder.CreateCall(CGM.getLLVMLifetimeStartFn(), {SizeV, Addr});
return SizeV;
void CodeGenFunction::EmitLifetimeEnd(llvm::Value *Size, llvm::Value *Addr) {
assert(Addr->getType()->getPointerAddressSpace() ==
CGM.getDataLayout().getAllocaAddrSpace() &&
"Pointer should be in alloca address space");
Addr = Builder.CreateBitCast(Addr, AllocaInt8PtrTy);
llvm::CallInst *C =
Builder.CreateCall(CGM.getLLVMLifetimeEndFn(), {Size, Addr});
void CodeGenFunction::EmitAndRegisterVariableArrayDimensions(
CGDebugInfo *DI, const VarDecl &D, bool EmitDebugInfo) {
// For each dimension stores its QualType and corresponding
// size-expression Value.
SmallVector<CodeGenFunction::VlaSizePair, 4> Dimensions;
SmallVector<IdentifierInfo *, 4> VLAExprNames;
// Break down the array into individual dimensions.
QualType Type1D = D.getType();
while (getContext().getAsVariableArrayType(Type1D)) {
auto VlaSize = getVLAElements1D(Type1D);
if (auto *C = dyn_cast<llvm::ConstantInt>(VlaSize.NumElts))
Dimensions.emplace_back(C, Type1D.getUnqualifiedType());
else {
// Generate a locally unique name for the size expression.
Twine Name = Twine("__vla_expr") + Twine(VLAExprCounter++);
SmallString<12> Buffer;
StringRef NameRef = Name.toStringRef(Buffer);
auto &Ident = getContext().Idents.getOwn(NameRef);
auto SizeExprAddr =
CreateDefaultAlignTempAlloca(VlaSize.NumElts->getType(), NameRef);
Builder.CreateStore(VlaSize.NumElts, SizeExprAddr);
Type1D = VlaSize.Type;
if (!EmitDebugInfo)
// Register each dimension's size-expression with a DILocalVariable,
// so that it can be used by CGDebugInfo when instantiating a DISubrange
// to describe this array.
unsigned NameIdx = 0;
for (auto &VlaSize : Dimensions) {
llvm::Metadata *MD;
if (auto *C = dyn_cast<llvm::ConstantInt>(VlaSize.NumElts))
MD = llvm::ConstantAsMetadata::get(C);
else {
// Create an artificial VarDecl to generate debug info for.
IdentifierInfo *NameIdent = VLAExprNames[NameIdx++];
auto VlaExprTy = VlaSize.NumElts->getType()->getPointerElementType();
auto QT = getContext().getIntTypeForBitwidth(
VlaExprTy->getScalarSizeInBits(), false);
auto *ArtificialDecl = VarDecl::Create(
getContext(), const_cast<DeclContext *>(D.getDeclContext()),
D.getLocation(), D.getLocation(), NameIdent, QT,
getContext().CreateTypeSourceInfo(QT), SC_Auto);
MD = DI->EmitDeclareOfAutoVariable(ArtificialDecl, VlaSize.NumElts,
assert(MD && "No Size expression debug node created");
DI->registerVLASizeExpression(VlaSize.Type, MD);
/// EmitAutoVarAlloca - Emit the alloca and debug information for a
/// local variable. Does not emit initialization or destruction.
CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) {
QualType Ty = D.getType();
Ty.getAddressSpace() == LangAS::Default ||
(Ty.getAddressSpace() == LangAS::opencl_private && getLangOpts().OpenCL));
AutoVarEmission emission(D);
bool isEscapingByRef = D.isEscapingByref();
emission.IsEscapingByRef = isEscapingByRef;
CharUnits alignment = getContext().getDeclAlign(&D);
// If the type is variably-modified, emit all the VLA sizes for it.
if (Ty->isVariablyModifiedType())
auto *DI = getDebugInfo();
bool EmitDebugInfo = DI && CGM.getCodeGenOpts().hasReducedDebugInfo();
Address address = Address::invalid();
Address AllocaAddr = Address::invalid();
Address OpenMPLocalAddr = Address::invalid();
if (CGM.getLangOpts().OpenMPIRBuilder)
OpenMPLocalAddr = OMPBuilderCBHelpers::getAddressOfLocalVariable(*this, &D);
OpenMPLocalAddr =
? CGM.getOpenMPRuntime().getAddressOfLocalVariable(*this, &D)
: Address::invalid();
bool NRVO = getLangOpts().ElideConstructors && D.isNRVOVariable();
if (getLangOpts().OpenMP && OpenMPLocalAddr.isValid()) {
address = OpenMPLocalAddr;
AllocaAddr = OpenMPLocalAddr;
} else if (Ty->isConstantSizeType()) {
// If this value is an array or struct with a statically determinable
// constant initializer, there are optimizations we can do.
// TODO: We should constant-evaluate the initializer of any variable,
// as long as it is initialized by a constant expression. Currently,
// isConstantInitializer produces wrong answers for structs with
// reference or bitfield members, and a few other cases, and checking
// for POD-ness protects us from some of these.
if (D.getInit() && (Ty->isArrayType() || Ty->isRecordType()) &&
(D.isConstexpr() ||
((Ty.isPODType(getContext()) ||
getContext().getBaseElementType(Ty)->isObjCObjectPointerType()) &&
D.getInit()->isConstantInitializer(getContext(), false)))) {
// If the variable's a const type, and it's neither an NRVO
// candidate nor a __block variable and has no mutable members,
// emit it as a global instead.
// Exception is if a variable is located in non-constant address space
// in OpenCL.
if ((!getLangOpts().OpenCL ||
Ty.getAddressSpace() == LangAS::opencl_constant) &&
(CGM.getCodeGenOpts().MergeAllConstants && !NRVO &&
!isEscapingByRef && CGM.isTypeConstant(Ty, true))) {
EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage);
// Signal this condition to later callbacks.
emission.Addr = Address::invalid();
return emission;
// Otherwise, tell the initialization code that we're in this case.
emission.IsConstantAggregate = true;
// A normal fixed sized variable becomes an alloca in the entry block,
// unless:
// - it's an NRVO variable.
// - we are compiling OpenMP and it's an OpenMP local variable.
if (NRVO) {
// The named return value optimization: allocate this variable in the
// return slot, so that we can elide the copy when returning this
// variable (C++0x [class.copy]p34).
address = ReturnValue;
AllocaAddr = ReturnValue;
if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
const auto *RD = RecordTy->getDecl();
const auto *CXXRD = dyn_cast<CXXRecordDecl>(RD);
if ((CXXRD && !CXXRD->hasTrivialDestructor()) ||
RD->isNonTrivialToPrimitiveDestroy()) {
// Create a flag that is used to indicate when the NRVO was applied
// to this variable. Set it to zero to indicate that NRVO was not
// applied.
llvm::Value *Zero = Builder.getFalse();
Address NRVOFlag =
CreateTempAlloca(Zero->getType(), CharUnits::One(), "nrvo",
/*ArraySize=*/nullptr, &AllocaAddr);
Builder.CreateStore(Zero, NRVOFlag);
// Record the NRVO flag for this variable.
NRVOFlags[&D] = NRVOFlag.getPointer();
emission.NRVOFlag = NRVOFlag.getPointer();
} else {
CharUnits allocaAlignment;
llvm::Type *allocaTy;
if (isEscapingByRef) {
auto &byrefInfo = getBlockByrefInfo(&D);
allocaTy = byrefInfo.Type;
allocaAlignment = byrefInfo.ByrefAlignment;
} else {
allocaTy = ConvertTypeForMem(Ty);
allocaAlignment = alignment;
// Create the alloca. Note that we set the name separately from
// building the instruction so that it's there even in no-asserts
// builds.
address = CreateTempAlloca(allocaTy, allocaAlignment, D.getName(),
/*ArraySize=*/nullptr, &AllocaAddr);
// Don't emit lifetime markers for MSVC catch parameters. The lifetime of
// the catch parameter starts in the catchpad instruction, and we can't
// insert code in those basic blocks.
bool IsMSCatchParam =
D.isExceptionVariable() && getTarget().getCXXABI().isMicrosoft();
// Emit a lifetime intrinsic if meaningful. There's no point in doing this
// if we don't have a valid insertion point (?).
if (HaveInsertPoint() && !IsMSCatchParam) {
// If there's a jump into the lifetime of this variable, its lifetime
// gets broken up into several regions in IR, which requires more work
// to handle correctly. For now, just omit the intrinsics; this is a
// rare case, and it's better to just be conservatively correct.
// PR28267.
// We have to do this in all language modes if there's a jump past the
// declaration. We also have to do it in C if there's a jump to an
// earlier point in the current block because non-VLA lifetimes begin as
// soon as the containing block is entered, not when its variables
// actually come into scope; suppressing the lifetime annotations
// completely in this case is unnecessarily pessimistic, but again, this
// is rare.
if (!Bypasses.IsBypassed(&D) &&
!(!getLangOpts().CPlusPlus && hasLabelBeenSeenInCurrentScope())) {
llvm::TypeSize Size = CGM.getDataLayout().getTypeAllocSize(allocaTy);
emission.SizeForLifetimeMarkers =
EmitLifetimeStart(Size, AllocaAddr.getPointer());
} else {
} else {
if (!DidCallStackSave) {
// Save the stack.
Address Stack =
CreateTempAlloca(Int8PtrTy, getPointerAlign(), "saved_stack");
llvm::Function *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave);
llvm::Value *V = Builder.CreateCall(F);
Builder.CreateStore(V, Stack);
DidCallStackSave = true;
// Push a cleanup block and restore the stack there.
// FIXME: in general circumstances, this should be an EH cleanup.
pushStackRestore(NormalCleanup, Stack);
auto VlaSize = getVLASize(Ty);
llvm::Type *llvmTy = ConvertTypeForMem(VlaSize.Type);
// Allocate memory for the array.
address = CreateTempAlloca(llvmTy, alignment, "vla", VlaSize.NumElts,
// If we have debug info enabled, properly describe the VLA dimensions for
// this type by registering the vla size expression for each of the
// dimensions.
EmitAndRegisterVariableArrayDimensions(DI, D, EmitDebugInfo);
setAddrOfLocalVar(&D, address);
emission.Addr = address;
emission.AllocaAddr = AllocaAddr;
// Emit debug info for local var declaration.
if (EmitDebugInfo && HaveInsertPoint()) {
Address DebugAddr = address;
bool UsePointerValue = NRVO && ReturnValuePointer.isValid();
// If NRVO, use a pointer to the return address.
if (UsePointerValue) {
DebugAddr = ReturnValuePointer;
AllocaAddr = ReturnValuePointer;
(void)DI->EmitDeclareOfAutoVariable(&D, AllocaAddr.getPointer(), Builder,
if (D.hasAttr<AnnotateAttr>() && HaveInsertPoint())
EmitVarAnnotations(&D, address.getPointer());
// Make sure we call @llvm.lifetime.end.
if (emission.useLifetimeMarkers())
return emission;
static bool isCapturedBy(const VarDecl &, const Expr *);
/// Determines whether the given __block variable is potentially
/// captured by the given statement.
static bool isCapturedBy(const VarDecl &Var, const Stmt *S) {
if (const Expr *E = dyn_cast<Expr>(S))
return isCapturedBy(Var, E);
for (const Stmt *SubStmt : S->children())
if (isCapturedBy(Var, SubStmt))
return true;
return false;
/// Determines whether the given __block variable is potentially
/// captured by the given expression.
static bool isCapturedBy(const VarDecl &Var, const Expr *E) {
// Skip the most common kinds of expressions that make
// hierarchy-walking expensive.
E = E->IgnoreParenCasts();
if (const BlockExpr *BE = dyn_cast<BlockExpr>(E)) {
const BlockDecl *Block = BE->getBlockDecl();
for (const auto &I : Block->captures()) {
if (I.getVariable() == &Var)
return true;
// No need to walk into the subexpressions.
return false;
if (const StmtExpr *SE = dyn_cast<StmtExpr>(E)) {
const CompoundStmt *CS = SE->getSubStmt();
for (const auto *BI : CS->body())
if (const auto *BIE = dyn_cast<Expr>(BI)) {
if (isCapturedBy(Var, BIE))
return true;
else if (const auto *DS = dyn_cast<DeclStmt>(BI)) {
// special case declarations
for (const auto *I : DS->decls()) {
if (const auto *VD = dyn_cast<VarDecl>((I))) {
const Expr *Init = VD->getInit();
if (Init && isCapturedBy(Var, Init))
return true;
// FIXME. Make safe assumption assuming arbitrary statements cause capturing.
// Later, provide code to poke into statements for capture analysis.
return true;
return false;
for (const Stmt *SubStmt : E->children())
if (isCapturedBy(Var, SubStmt))
return true;
return false;
/// Determine whether the given initializer is trivial in the sense
/// that it requires no code to be generated.
bool CodeGenFunction::isTrivialInitializer(const Expr *Init) {
if (!Init)
return true;
if (const CXXConstructExpr *Construct = dyn_cast<CXXConstructExpr>(Init))
if (CXXConstructorDecl *Constructor = Construct->getConstructor())
if (Constructor->isTrivial() &&
Constructor->isDefaultConstructor() &&
return true;
return false;
void CodeGenFunction::emitZeroOrPatternForAutoVarInit(QualType type,
const VarDecl &D,
Address Loc) {
auto trivialAutoVarInit = getContext().getLangOpts().getTrivialAutoVarInit();
CharUnits Size = getContext().getTypeSizeInChars(type);
bool isVolatile = type.isVolatileQualified();
if (!Size.isZero()) {
switch (trivialAutoVarInit) {
case LangOptions::TrivialAutoVarInitKind::Uninitialized:
llvm_unreachable("Uninitialized handled by caller");
case LangOptions::TrivialAutoVarInitKind::Zero:
if (CGM.stopAutoInit())
emitStoresForZeroInit(CGM, D, Loc, isVolatile, Builder);
case LangOptions::TrivialAutoVarInitKind::Pattern:
if (CGM.stopAutoInit())
emitStoresForPatternInit(CGM, D, Loc, isVolatile, Builder);
// VLAs look zero-sized to getTypeInfo. We can't emit constant stores to
// them, so emit a memcpy with the VLA size to initialize each element.
// Technically zero-sized or negative-sized VLAs are undefined, and UBSan
// will catch that code, but there exists code which generates zero-sized
// VLAs. Be nice and initialize whatever they requested.
const auto *VlaType = getContext().getAsVariableArrayType(type);
if (!VlaType)
auto VlaSize = getVLASize(VlaType);
auto SizeVal = VlaSize.NumElts;
CharUnits EltSize = getContext().getTypeSizeInChars(VlaSize.Type);
switch (trivialAutoVarInit) {
case LangOptions::TrivialAutoVarInitKind::Uninitialized:
llvm_unreachable("Uninitialized handled by caller");
case LangOptions::TrivialAutoVarInitKind::Zero: {
if (CGM.stopAutoInit())
if (!EltSize.isOne())
SizeVal = Builder.CreateNUWMul(SizeVal, CGM.getSize(EltSize));
auto *I = Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, 0),
SizeVal, isVolatile);
case LangOptions::TrivialAutoVarInitKind::Pattern: {
if (CGM.stopAutoInit())
llvm::Type *ElTy = Loc.getElementType();
llvm::Constant *Constant = constWithPadding(
CGM, IsPattern::Yes, initializationPatternFor(CGM, ElTy));
CharUnits ConstantAlign = getContext().getTypeAlignInChars(VlaSize.Type);
llvm::BasicBlock *SetupBB = createBasicBlock("vla-setup.loop");
llvm::BasicBlock *LoopBB = createBasicBlock("vla-init.loop");
llvm::BasicBlock *ContBB = createBasicBlock("vla-init.cont");
llvm::Value *IsZeroSizedVLA = Builder.CreateICmpEQ(
SizeVal, llvm::ConstantInt::get(SizeVal->getType(), 0),
Builder.CreateCondBr(IsZeroSizedVLA, ContBB, SetupBB);
if (!EltSize.isOne())
SizeVal = Builder.CreateNUWMul(SizeVal, CGM.getSize(EltSize));
llvm::Value *BaseSizeInChars =
llvm::ConstantInt::get(IntPtrTy, EltSize.getQuantity());
Address Begin = Builder.CreateElementBitCast(Loc, Int8Ty, "vla.begin");
llvm::Value *End = Builder.CreateInBoundsGEP(
Begin.getElementType(), Begin.getPointer(), SizeVal, "vla.end");
llvm::BasicBlock *OriginBB = Builder.GetInsertBlock();
llvm::PHINode *Cur = Builder.CreatePHI(Begin.getType(), 2, "vla.cur");
Cur->addIncoming(Begin.getPointer(), OriginBB);
CharUnits CurAlign = Loc.getAlignment().alignmentOfArrayElement(EltSize);
auto *I =
Builder.CreateMemCpy(Address(Cur, CurAlign),
CGM, D, Builder, Constant, ConstantAlign),
BaseSizeInChars, isVolatile);
llvm::Value *Next =
Builder.CreateInBoundsGEP(Int8Ty, Cur, BaseSizeInChars, "");
llvm::Value *Done = Builder.CreateICmpEQ(Next, End, "vla-init.isdone");
Builder.CreateCondBr(Done, ContBB, LoopBB);
Cur->addIncoming(Next, LoopBB);
} break;
void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) {
assert(emission.Variable && "emission was not valid!");
// If this was emitted as a global constant, we're done.
if (emission.wasEmittedAsGlobal()) return;
const VarDecl &D = *emission.Variable;
auto DL = ApplyDebugLocation::CreateDefaultArtificial(*this, D.getLocation());
QualType type = D.getType();
// If this local has an initializer, emit it now.
const Expr *Init = D.getInit();
// If we are at an unreachable point, we don't need to emit the initializer
// unless it contains a label.
if (!HaveInsertPoint()) {
if (!Init || !ContainsLabel(Init)) return;
// Initialize the structure of a __block variable.
if (emission.IsEscapingByRef)
// Initialize the variable here if it doesn't have a initializer and it is a
// C struct that is non-trivial to initialize or an array containing such a
// struct.
if (!Init &&
type.isNonTrivialToPrimitiveDefaultInitialize() ==
QualType::PDIK_Struct) {
LValue Dst = MakeAddrLValue(emission.getAllocatedAddress(), type);
if (emission.IsEscapingByRef)
drillIntoBlockVariable(*this, Dst, &D);
// Check whether this is a byref variable that's potentially
// captured and moved by its own initializer. If so, we'll need to
// emit the initializer first, then copy into the variable.
bool capturedByInit =
Init && emission.IsEscapingByRef && isCapturedBy(D, Init);
bool locIsByrefHeader = !capturedByInit;
const Address Loc =
locIsByrefHeader ? emission.getObjectAddress(*this) : emission.Addr;
// Note: constexpr already initializes everything correctly.
LangOptions::TrivialAutoVarInitKind trivialAutoVarInit =
? LangOptions::TrivialAutoVarInitKind::Uninitialized
: (D.getAttr<UninitializedAttr>()
? LangOptions::TrivialAutoVarInitKind::Uninitialized
: getContext().getLangOpts().getTrivialAutoVarInit()));
auto initializeWhatIsTechnicallyUninitialized = [&](Address Loc) {
if (trivialAutoVarInit ==
// Only initialize a __block's storage: we always initialize the header.
if (emission.IsEscapingByRef && !locIsByrefHeader)
Loc = emitBlockByrefAddress(Loc, &D, /*follow=*/false);
return emitZeroOrPatternForAutoVarInit(type, D, Loc);
if (isTrivialInitializer(Init))
return initializeWhatIsTechnicallyUninitialized(Loc);
llvm::Constant *constant = nullptr;
if (emission.IsConstantAggregate ||
D.mightBeUsableInConstantExpressions(getContext())) {
assert(!capturedByInit && "constant init contains a capturing block?");
constant = ConstantEmitter(*this).tryEmitAbstractForInitializer(D);
if (constant && !constant->isZeroValue() &&
(trivialAutoVarInit !=
LangOptions::TrivialAutoVarInitKind::Uninitialized)) {
IsPattern isPattern =
(trivialAutoVarInit == LangOptions::TrivialAutoVarInitKind::Pattern)
? IsPattern::Yes
: IsPattern::No;
// C guarantees that brace-init with fewer initializers than members in
// the aggregate will initialize the rest of the aggregate as-if it were
// static initialization. In turn static initialization guarantees that
// padding is initialized to zero bits. We could instead pattern-init if D
// has any ImplicitValueInitExpr, but that seems to be unintuitive
// behavior.
constant = constWithPadding(CGM, IsPattern::No,
replaceUndef(CGM, isPattern, constant));
if (!constant) {
LValue lv = MakeAddrLValue(Loc, type);
return EmitExprAsInit(Init, &D, lv, capturedByInit);
if (!emission.IsConstantAggregate) {
// For simple scalar/complex initialization, store the value directly.
LValue lv = MakeAddrLValue(Loc, type);
return EmitStoreThroughLValue(RValue::get(constant), lv, true);
llvm::Type *BP = CGM.Int8Ty->getPointerTo(Loc.getAddressSpace());
CGM, D, (Loc.getType() == BP) ? Loc : Builder.CreateBitCast(Loc, BP),
type.isVolatileQualified(), Builder, constant, /*IsAutoInit=*/false);
/// Emit an expression as an initializer for an object (variable, field, etc.)
/// at the given location. The expression is not necessarily the normal
/// initializer for the object, and the address is not necessarily
/// its normal location.
/// \param init the initializing expression
/// \param D the object to act as if we're initializing
/// \param lvalue the lvalue to initialize
/// \param capturedByInit true if \p D is a __block variable
/// whose address is potentially changed by the initializer
void CodeGenFunction::EmitExprAsInit(const Expr *init, const ValueDecl *D,
LValue lvalue, bool capturedByInit) {
QualType type = D->getType();
if (type->isReferenceType()) {
RValue rvalue = EmitReferenceBindingToExpr(init);
if (capturedByInit)
drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
EmitStoreThroughLValue(rvalue, lvalue, true);
switch (getEvaluationKind(type)) {
case TEK_Scalar:
EmitScalarInit(init, D, lvalue, capturedByInit);
case TEK_Complex: {
ComplexPairTy complex = EmitComplexExpr(init);
if (capturedByInit)
drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
EmitStoreOfComplex(complex, lvalue, /*init*/ true);
case TEK_Aggregate:
if (type->isAtomicType()) {
EmitAtomicInit(const_cast<Expr*>(init), lvalue);
} else {
AggValueSlot::Overlap_t Overlap = AggValueSlot::MayOverlap;
if (isa<VarDecl>(D))
Overlap = AggValueSlot::DoesNotOverlap;
else if (auto *FD = dyn_cast<FieldDecl>(D))
Overlap = getOverlapForFieldInit(FD);
// TODO: how can we delay here if D is captured by its initializer?
EmitAggExpr(init, AggValueSlot::forLValue(
lvalue, *this, AggValueSlot::IsDestructed,
AggValueSlot::IsNotAliased, Overlap));
llvm_unreachable("bad evaluation kind");
/// Enter a destroy cleanup for the given local variable.
void CodeGenFunction::emitAutoVarTypeCleanup(
const CodeGenFunction::AutoVarEmission &emission,
QualType::DestructionKind dtorKind) {
assert(dtorKind != QualType::DK_none);
// Note that for __block variables, we want to destroy the
// original stack object, not the possibly forwarded object.
Address addr = emission.getObjectAddress(*this);
const VarDecl *var = emission.Variable;
QualType type = var->getType();
CleanupKind cleanupKind = NormalAndEHCleanup;
CodeGenFunction::Destroyer *destroyer = nullptr;
switch (dtorKind) {
case QualType::DK_none:
llvm_unreachable("no cleanup for trivially-destructible variable");
case QualType::DK_cxx_destructor:
// If there's an NRVO flag on the emission, we need a different
// cleanup.
if (emission.NRVOFlag) {
CXXDestructorDecl *dtor = type->getAsCXXRecordDecl()->getDestructor();
EHStack.pushCleanup<DestroyNRVOVariableCXX>(cleanupKind, addr, type, dtor,
case QualType::DK_objc_strong_lifetime:
// Suppress cleanups for pseudo-strong variables.
if (var->isARCPseudoStrong()) return;
// Otherwise, consider whether to use an EH cleanup or not.
cleanupKind = getARCCleanupKind();
// Use the imprecise destroyer by default.
if (!var->hasAttr<ObjCPreciseLifetimeAttr>())
destroyer = CodeGenFunction::destroyARCStrongImprecise;
case QualType::DK_objc_weak_lifetime:
case QualType::DK_nontrivial_c_struct:
destroyer = CodeGenFunction::destroyNonTrivialCStruct;
if (emission.NRVOFlag) {
EHStack.pushCleanup<DestroyNRVOVariableC>(cleanupKind, addr,
emission.NRVOFlag, type);
// If we haven't chosen a more specific destroyer, use the default.
if (!destroyer) destroyer = getDestroyer(dtorKind);
// Use an EH cleanup in array destructors iff the destructor itself
// is being pushed as an EH cleanup.
bool useEHCleanup = (cleanupKind & EHCleanup);
EHStack.pushCleanup<DestroyObject>(cleanupKind, addr, type, destroyer,
void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) {
assert(emission.Variable && "emission was not valid!");
// If this was emitted as a global constant, we're done.
if (emission.wasEmittedAsGlobal()) return;
// If we don't have an insertion point, we're done. Sema prevents
// us from jumping into any of these scopes anyway.
if (!HaveInsertPoint()) return;
const VarDecl &D = *emission.Variable;
// Check the type for a cleanup.
if (QualType::DestructionKind dtorKind = D.needsDestruction(getContext()))
emitAutoVarTypeCleanup(emission, dtorKind);
// In GC mode, honor objc_precise_lifetime.
if (getLangOpts().getGC() != LangOptions::NonGC &&
D.hasAttr<ObjCPreciseLifetimeAttr>()) {
EHStack.pushCleanup<ExtendGCLifetime>(NormalCleanup, &D);
// Handle the cleanup attribute.
if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) {
const FunctionDecl *FD = CA->getFunctionDecl();
llvm::Constant *F = CGM.GetAddrOfFunction(FD);
assert(F && "Could not find function!");
const CGFunctionInfo &Info = CGM.getTypes().arrangeFunctionDeclaration(FD);
EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup, F, &Info, &D);
// If this is a block variable, call _Block_object_destroy
// (on the unforwarded address). Don't enter this cleanup if we're in pure-GC
// mode.
if (emission.IsEscapingByRef &&
CGM.getLangOpts().getGC() != LangOptions::GCOnly) {
BlockFieldFlags Flags = BLOCK_FIELD_IS_BYREF;
if (emission.Variable->getType().isObjCGCWeak())
enterByrefCleanup(NormalAndEHCleanup, emission.Addr, Flags,
/*LoadBlockVarAddr*/ false,
CodeGenFunction::Destroyer *
CodeGenFunction::getDestroyer(QualType::DestructionKind kind) {
switch (kind) {
case QualType::DK_none: llvm_unreachable("no destroyer for trivial dtor");
case QualType::DK_cxx_destructor:
return destroyCXXObject;
case QualType::DK_objc_strong_lifetime:
return destroyARCStrongPrecise;
case QualType::DK_objc_weak_lifetime:
return destroyARCWeak;
case QualType::DK_nontrivial_c_struct:
return destroyNonTrivialCStruct;
llvm_unreachable("Unknown DestructionKind");
/// pushEHDestroy - Push the standard destructor for the given type as
/// an EH-only cleanup.
void CodeGenFunction::pushEHDestroy(QualType::DestructionKind dtorKind,
Address addr, QualType type) {
assert(dtorKind && "cannot push destructor for trivial type");
pushDestroy(EHCleanup, addr, type, getDestroyer(dtorKind), true);
/// pushDestroy - Push the standard destructor for the given type as
/// at least a normal cleanup.
void CodeGenFunction::pushDestroy(QualType::DestructionKind dtorKind,
Address addr, QualType type) {
assert(dtorKind && "cannot push destructor for trivial type");
CleanupKind cleanupKind = getCleanupKind(dtorKind);
pushDestroy(cleanupKind, addr, type, getDestroyer(dtorKind),
cleanupKind & EHCleanup);
void CodeGenFunction::pushDestroy(CleanupKind cleanupKind, Address addr,
QualType type, Destroyer *destroyer,
bool useEHCleanupForArray) {
pushFullExprCleanup<DestroyObject>(cleanupKind, addr, type,
destroyer, useEHCleanupForArray);
void CodeGenFunction::pushStackRestore(CleanupKind Kind, Address SPMem) {
EHStack.pushCleanup<CallStackRestore>(Kind, SPMem);
void CodeGenFunction::pushLifetimeExtendedDestroy(CleanupKind cleanupKind,
Address addr, QualType type,
Destroyer *destroyer,
bool useEHCleanupForArray) {
// If we're not in a conditional branch, we don't need to bother generating a
// conditional cleanup.
if (!isInConditionalBranch()) {
// Push an EH-only cleanup for the object now.
// FIXME: When popping normal cleanups, we need to keep this EH cleanup
// around in case a temporary's destructor throws an exception.
if (cleanupKind & EHCleanup)
static_cast<CleanupKind>(cleanupKind & ~NormalCleanup), addr, type,
destroyer, useEHCleanupForArray);
return pushCleanupAfterFullExprWithActiveFlag<DestroyObject>(
cleanupKind, Address::invalid(), addr, type, destroyer, useEHCleanupForArray);
// Otherwise, we should only destroy the object if it's been initialized.
// Re-use the active flag and saved address across both the EH and end of
// scope cleanups.
using SavedType = typename DominatingValue<Address>::saved_type;
using ConditionalCleanupType =
EHScopeStack::ConditionalCleanup<DestroyObject, Address, QualType,
Destroyer *, bool>;
Address ActiveFlag = createCleanupActiveFlag();
SavedType SavedAddr = saveValueInCond(addr);
if (cleanupKind & EHCleanup) {
static_cast<CleanupKind>(cleanupKind & ~NormalCleanup), SavedAddr, type,
destroyer, useEHCleanupForArray);
cleanupKind, ActiveFlag, SavedAddr, type, destroyer,
/// emitDestroy - Immediately perform the destruction of the given
/// object.
/// \param addr - the address of the object; a type*
/// \param type - the type of the object; if an array type, all
/// objects are destroyed in reverse order
/// \param destroyer - the function to call to destroy individual
/// elements
/// \param useEHCleanupForArray - whether an EH cleanup should be
/// used when destroying array elements, in case one of the
/// destructions throws an exception
void CodeGenFunction::emitDestroy(Address addr, QualType type,
Destroyer *destroyer,
bool useEHCleanupForArray) {
const ArrayType *arrayType = getContext().getAsArrayType(type);
if (!arrayType)
return destroyer(*this, addr, type);
llvm::Value *length = emitArrayLength(arrayType, type, addr);
CharUnits elementAlign =
// Normally we have to check whether the array is zero-length.
bool checkZeroLength = true;
// But if the array length is constant, we can suppress that.
if (llvm::ConstantInt *constLength = dyn_cast<llvm::ConstantInt>(length)) {
// ...and if it's constant zero, we can just skip the entire thing.
if (constLength->isZero()) return;
checkZeroLength = false;
llvm::Value *begin = addr.getPointer();
llvm::Value *end =
Builder.CreateInBoundsGEP(addr.getElementType(), begin, length);
emitArrayDestroy(begin, end, type, elementAlign, destroyer,
checkZeroLength, useEHCleanupForArray);
/// emitArrayDestroy - Destroys all the elements of the given array,
/// beginning from last to first. The array cannot be zero-length.
/// \param begin - a type* denoting the first element of the array
/// \param end - a type* denoting one past the end of the array
/// \param elementType - the element type of the array
/// \param destroyer - the function to call to destroy elements
/// \param useEHCleanup - whether to push an EH cleanup to destroy
/// the remaining elements in case the destruction of a single
/// element throws
void CodeGenFunction::emitArrayDestroy(llvm::Value *begin,
llvm::Value *end,
QualType elementType,
CharUnits elementAlign,
Destroyer *destroyer,
bool checkZeroLength,
bool useEHCleanup) {
// The basic structure here is a do-while loop, because we don't
// need to check for the zero-element case.
llvm::BasicBlock *bodyBB = createBasicBlock("arraydestroy.body");
llvm::BasicBlock *doneBB = createBasicBlock("arraydestroy.done");
if (checkZeroLength) {
llvm::Value *isEmpty = Builder.CreateICmpEQ(begin, end,
Builder.CreateCondBr(isEmpty, doneBB, bodyBB);
// Enter the loop body, making that address the current address.
llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
llvm::PHINode *elementPast =
Builder.CreatePHI(begin->getType(), 2, "arraydestroy.elementPast");
elementPast->addIncoming(end, entryBB);
// Shift the address back by one element.
llvm::Value *negativeOne = llvm::ConstantInt::get(SizeTy, -1, true);
llvm::Value *element = Builder.CreateInBoundsGEP(
elementPast->getType()->getPointerElementType(), elementPast, negativeOne,
if (useEHCleanup)
pushRegularPartialArrayCleanup(begin, element, elementType, elementAlign,
// Perform the actual destruction there.
destroyer(*this, Address(element, elementAlign), elementType);
if (useEHCleanup)
// Check whether we've reached the end.
llvm::Value *done = Builder.CreateICmpEQ(element, begin, "arraydestroy.done");
Builder.CreateCondBr(done, doneBB, bodyBB);
elementPast->addIncoming(element, Builder.GetInsertBlock());
// Done.
/// Perform partial array destruction as if in an EH cleanup. Unlike
/// emitArrayDestroy, the element type here may still be an array type.
static void emitPartialArrayDestroy(CodeGenFunction &CGF,
llvm::Value *begin, llvm::Value *end,
QualType type, CharUnits elementAlign,
CodeGenFunction::Destroyer *destroyer) {
// If the element type is itself an array, drill down.
unsigned arrayDepth = 0;
while (const ArrayType *arrayType = CGF.getContext().getAsArrayType(type)) {
// VLAs don't require a GEP index to walk into.
if (!isa<VariableArrayType>(arrayType))
type = arrayType->getElementType();
if (arrayDepth) {
llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, 0);
SmallVector<llvm::Value*,4> gepIndices(arrayDepth+1, zero);
llvm::Type *elemTy = begin->getType()->getPointerElementType();
begin = CGF.Builder.CreateInBoundsGEP(
elemTy, begin, gepIndices, "pad.arraybegin");
end = CGF.Builder.CreateInBoundsGEP(
elemTy, end, gepIndices, "pad.arrayend");
// Destroy the array. We don't ever need an EH cleanup because we
// assume that we're in an EH cleanup ourselves, so a throwing
// destructor causes an immediate terminate.
CGF.emitArrayDestroy(begin, end, type, elementAlign, destroyer,
/*checkZeroLength*/ true, /*useEHCleanup*/ false);
namespace {
/// RegularPartialArrayDestroy - a cleanup which performs a partial
/// array destroy where the end pointer is regularly determined and
/// does not need to be loaded from a local.
class RegularPartialArrayDestroy final : public EHScopeStack::Cleanup {
llvm::Value *ArrayBegin;
llvm::Value *ArrayEnd;
QualType ElementType;
CodeGenFunction::Destroyer *Destroyer;
CharUnits ElementAlign;
RegularPartialArrayDestroy(llvm::Value *arrayBegin, llvm::Value *arrayEnd,
QualType elementType, CharUnits elementAlign,
CodeGenFunction::Destroyer *destroyer)
: ArrayBegin(arrayBegin), ArrayEnd(arrayEnd),
ElementType(elementType), Destroyer(destroyer),
ElementAlign(elementAlign) {}
void Emit(CodeGenFunction &CGF, Flags flags) override {
emitPartialArrayDestroy(CGF, ArrayBegin, ArrayEnd,
ElementType, ElementAlign, Destroyer);
/// IrregularPartialArrayDestroy - a cleanup which performs a
/// partial array destroy where the end pointer is irregularly
/// determined and must be loaded from a local.
class IrregularPartialArrayDestroy final : public EHScopeStack::Cleanup {
llvm::Value *ArrayBegin;
Address ArrayEndPointer;
QualType ElementType;
CodeGenFunction::Destroyer *Destroyer;
CharUnits ElementAlign;
IrregularPartialArrayDestroy(llvm::Value *arrayBegin,
Address arrayEndPointer,
QualType elementType,
CharUnits elementAlign,
CodeGenFunction::Destroyer *destroyer)
: ArrayBegin(arrayBegin), ArrayEndPointer(arrayEndPointer),
ElementType(elementType), Destroyer(destroyer),
ElementAlign(elementAlign) {}
void Emit(CodeGenFunction &CGF, Flags flags) override {
llvm::Value *arrayEnd = CGF.Builder.CreateLoad(ArrayEndPointer);
emitPartialArrayDestroy(CGF, ArrayBegin, arrayEnd,
ElementType, ElementAlign, Destroyer);
} // end anonymous namespace
/// pushIrregularPartialArrayCleanup - Push an EH cleanup to destroy
/// already-constructed elements of the given array. The cleanup
/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
/// \param elementType - the immediate element type of the array;
/// possibly still an array type
void CodeGenFunction::pushIrregularPartialArrayCleanup(llvm::Value *arrayBegin,
Address arrayEndPointer,
QualType elementType,
CharUnits elementAlign,
Destroyer *destroyer) {
arrayBegin, arrayEndPointer,
elementType, elementAlign,
/// pushRegularPartialArrayCleanup - Push an EH cleanup to destroy
/// already-constructed elements of the given array. The cleanup
/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
/// \param elementType - the immediate element type of the array;
/// possibly still an array type
void CodeGenFunction::pushRegularPartialArrayCleanup(llvm::Value *arrayBegin,
llvm::Value *arrayEnd,
QualType elementType,
CharUnits elementAlign,
Destroyer *destroyer) {
arrayBegin, arrayEnd,
elementType, elementAlign,
/// Lazily declare the @llvm.lifetime.start intrinsic.
llvm::Function *CodeGenModule::getLLVMLifetimeStartFn() {
if (LifetimeStartFn)
return LifetimeStartFn;
LifetimeStartFn = llvm::Intrinsic::getDeclaration(&getModule(),
llvm::Intrinsic::lifetime_start, AllocaInt8PtrTy);
return LifetimeStartFn;
/// Lazily declare the @llvm.lifetime.end intrinsic.
llvm::Function *CodeGenModule::getLLVMLifetimeEndFn() {
if (LifetimeEndFn)
return LifetimeEndFn;
LifetimeEndFn = llvm::Intrinsic::getDeclaration(&getModule(),
llvm::Intrinsic::lifetime_end, AllocaInt8PtrTy);
return LifetimeEndFn;
namespace {
/// A cleanup to perform a release of an object at the end of a
/// function. This is used to balance out the incoming +1 of a
/// ns_consumed argument when we can't reasonably do that just by
/// not doing the initial retain for a __block argument.
struct ConsumeARCParameter final : EHScopeStack::Cleanup {
ConsumeARCParameter(llvm::Value *param,
ARCPreciseLifetime_t precise)
: Param(param), Precise(precise) {}
llvm::Value *Param;
ARCPreciseLifetime_t Precise;
void Emit(CodeGenFunction &CGF, Flags flags) override {
CGF.EmitARCRelease(Param, Precise);