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//===--- CGDecl.cpp - Emit LLVM Code for declarations ---------------------===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This contains code to emit Decl nodes as LLVM code.
#include "CodeGenFunction.h"
#include "CGBlocks.h"
#include "CGCXXABI.h"
#include "CGCleanup.h"
#include "CGDebugInfo.h"
#include "CGOpenCLRuntime.h"
#include "CGOpenMPRuntime.h"
#include "CodeGenModule.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/DeclOpenMP.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/CodeGen/CGFunctionInfo.h"
#include "clang/Frontend/CodeGenOptions.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;
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::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:
llvm_unreachable("Declaration should not be in declstmts!");
case Decl::Function: // void X();
case Decl::Record: // struct/union/class X;
case Decl::Enum: // enum X;
case Decl::EnumConstant: // enum ? { X = ? }
case Decl::CXXRecord: // struct/union/class X; [C++]
case Decl::StaticAssert: // static_assert(X, ""); [C++0x]
case Decl::Label: // __label__ x;
case Decl::Import:
case Decl::OMPThreadPrivate:
case Decl::OMPCapturedExpr:
case Decl::Empty:
// 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::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::Typedef: // typedef int X;
case Decl::TypeAlias: { // using X = int; [C++0x]
const TypedefNameDecl &TD = cast<TypedefNameDecl>(D);
QualType Ty = TD.getUnderlyingType();
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.isStaticLocal()) {
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.hasExternalStorage())
// Don't emit it now, allow it to be emitted lazily on its first use.
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 = CGM.getMangledName(FD);
else if (const auto *BD = dyn_cast<BlockDecl>(DC))
ContextName = 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 = getMangledName(&D);
Name = getStaticDeclName(*this, D);
llvm::Type *LTy = getTypes().ConvertTypeForMem(Ty);
unsigned AddrSpace =
GetGlobalVarAddressSpace(&D, getContext().getTargetAddressSpace(Ty));
// Local address space cannot have an initializer.
llvm::Constant *Init = nullptr;
if (Ty.getAddressSpace() != LangAS::opencl_local)
Init = EmitNullConstant(Ty);
Init = llvm::UndefValue::get(LTy);
llvm::GlobalVariable *GV =
new llvm::GlobalVariable(getModule(), LTy,
Ty.isConstant(getContext()), Linkage,
Init, Name, nullptr,
setGlobalVisibility(GV, &D);
if (supportsCOMDAT() && GV->isWeakForLinker())
if (D.getTLSKind())
setTLSMode(GV, D);
if (D.isExternallyVisible()) {
if (D.hasAttr<DLLImportAttr>())
else if (D.hasAttr<DLLExportAttr>())
// Make sure the result is of the correct type.
unsigned ExpectedAddrSpace = getContext().getTargetAddressSpace(Ty);
llvm::Constant *Addr = GV;
if (AddrSpace != ExpectedAddrSpace) {
llvm::PointerType *PTy = llvm::PointerType::get(LTy, ExpectedAddrSpace);
Addr = llvm::ConstantExpr::getAddrSpaceCast(GV, PTy);
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())
return Addr;
/// hasNontrivialDestruction - Determine whether a type's destruction is
/// non-trivial. If so, and the variable uses static initialization, we must
/// register its destructor to run on exit.
static bool hasNontrivialDestruction(QualType T) {
CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
return RD && !RD->hasTrivialDestructor();
/// 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) {
llvm::Constant *Init = CGM.EmitConstantInit(D, this);
// 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->getType()->getElementType() != Init->getType()) {
llvm::GlobalVariable *OldGV = GV;
GV = new llvm::GlobalVariable(CGM.getModule(), Init->getType(),
OldGV->getLinkage(), Init, "",
/*InsertBefore*/ OldGV,
// 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 (hasNontrivialDestruction(D.getType()) && 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 (const SectionAttr *SA = D.getAttr<SectionAttr>())
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().getDebugInfo() >= codegenoptions::LimitedDebugInfo) {
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);
struct DestroyNRVOVariable final : EHScopeStack::Cleanup {
DestroyNRVOVariable(Address addr,
const CXXDestructorDecl *Dtor,
llvm::Value *NRVOFlag)
: Dtor(Dtor), NRVOFlag(NRVOFlag), Loc(addr) {}
const CXXDestructorDecl *Dtor;
llvm::Value *NRVOFlag;
Address Loc;
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);
CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
if (NRVO) CGF.EmitBlock(SkipDtorBB);
struct CallStackRestore final : EHScopeStack::Cleanup {
Address Stack;
CallStackRestore(Address Stack) : Stack(Stack) {}
void Emit(CodeGenFunction &CGF, Flags flags) override {
llvm::Value *V = CGF.Builder.CreateLoad(Stack);
llvm::Value *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(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(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();
// 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();
if (needsCast) {
srcAddr = CGF.Builder.CreateElementBitCast(srcAddr,
// If it was an l-value, use objc_copyWeak.
if (srcExpr->getValueKind() == VK_LValue) {
CGF.EmitARCCopyWeak(destLV.getAddress(), srcAddr);
} else {
assert(srcExpr->getValueKind() == VK_XValue);
CGF.EmitARCMoveWeak(destLV.getAddress(), 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(), var));
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));
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 (const ExprWithCleanups *ewc = dyn_cast<ExprWithCleanups>(init)) {
init = ewc->getSubExpr();
CodeGenFunction::RunCleanupsScope Scope(*this);
// 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 = cast<llvm::PointerType>(tempLV.getAddress().getElementType());
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(), 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_ExplicitNone:
value = EmitARCUnsafeUnretainedScalarExpr(init);
case Qualifiers::OCL_Strong: {
value = EmitARCRetainScalarExpr(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(), value, /*ignored*/ true);
EmitARCInitWeak(lvalue.getAddress(), value);
case Qualifiers::OCL_Autoreleasing:
value = EmitARCRetainAutoreleaseScalarExpr(init);
if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
// 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);
/// canEmitInitWithFewStoresAfterMemset - Decide whether we can emit the
/// non-zero parts of the specified initializer with equal or fewer than
/// NumStores scalar stores.
static bool canEmitInitWithFewStoresAfterMemset(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 (!canEmitInitWithFewStoresAfterMemset(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 (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores))
return false;
return true;
// Anything else is hard and scary.
return false;
/// emitStoresForInitAfterMemset - For inits that
/// canEmitInitWithFewStoresAfterMemset returned true for, emit the scalar
/// stores that would be required.
static void emitStoresForInitAfterMemset(llvm::Constant *Init, llvm::Value *Loc,
bool isVolatile, CGBuilderTy &Builder) {
assert(!Init->isNullValue() && !isa<llvm::UndefValue>(Init) &&
"called emitStoresForInitAfterMemset 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)) {
Builder.CreateDefaultAlignedStore(Init, Loc, isVolatile);
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))
Elt, Builder.CreateConstGEP2_32(Init->getType(), Loc, 0, i),
isVolatile, Builder);
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))
Elt, Builder.CreateConstGEP2_32(Init->getType(), Loc, 0, i),
isVolatile, Builder);
/// shouldUseMemSetPlusStoresToInitialize - Decide whether we should use memset
/// plus some stores to initialize a local variable instead of using a memcpy
/// from a constant global. It is beneficial to use memset if the global is all
/// zeros, or mostly zeros and large.
static bool shouldUseMemSetPlusStoresToInitialize(llvm::Constant *Init,
uint64_t GlobalSize) {
// If a global is all zeros, always use a memset.
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 &&
canEmitInitWithFewStoresAfterMemset(Init, StoreBudget);
/// 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(uint64_t Size,
llvm::Value *Addr) {
if (!ShouldEmitLifetimeMarkers)
return nullptr;
llvm::Value *SizeV = llvm::ConstantInt::get(Int64Ty, Size);
Addr = Builder.CreateBitCast(Addr, Int8PtrTy);
llvm::CallInst *C =
Builder.CreateCall(CGM.getLLVMLifetimeStartFn(), {SizeV, Addr});
return SizeV;
void CodeGenFunction::EmitLifetimeEnd(llvm::Value *Size, llvm::Value *Addr) {
Addr = Builder.CreateBitCast(Addr, Int8PtrTy);
llvm::CallInst *C =
Builder.CreateCall(CGM.getLLVMLifetimeEndFn(), {Size, Addr});
/// 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();
AutoVarEmission emission(D);
bool isByRef = D.hasAttr<BlocksAttr>();
emission.IsByRef = isByRef;
CharUnits alignment = getContext().getDeclAlign(&D);
// If the type is variably-modified, emit all the VLA sizes for it.
if (Ty->isVariablyModifiedType())
Address address = Address::invalid();
if (Ty->isConstantSizeType()) {
bool NRVO = getLangOpts().ElideConstructors &&
// 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 && !isByRef &&
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.
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;
if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
if (!cast<CXXRecordDecl>(RecordTy->getDecl())->hasTrivialDestructor()) {
// 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");
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 (isByRef) {
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);
// 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) {
// goto or switch-case statements can break lifetime into several
// regions which need more efforts to handle them correctly. PR28267
// This is rare case, but it's better just omit intrinsics than have
// them incorrectly placed.
if (!Bypasses.IsBypassed(&D)) {
uint64_t size = CGM.getDataLayout().getTypeAllocSize(allocaTy);
emission.SizeForLifetimeMarkers =
EmitLifetimeStart(size, address.getPointer());
} else {
} else {
if (!DidCallStackSave) {
// Save the stack.
Address Stack =
CreateTempAlloca(Int8PtrTy, getPointerAlign(), "saved_stack");
llvm::Value *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);
llvm::Value *elementCount;
QualType elementType;
std::tie(elementCount, elementType) = getVLASize(Ty);
llvm::Type *llvmTy = ConvertTypeForMem(elementType);
// Allocate memory for the array.
llvm::AllocaInst *vla = Builder.CreateAlloca(llvmTy, elementCount, "vla");
address = Address(vla, alignment);
setAddrOfLocalVar(&D, address);
emission.Addr = address;
// Emit debug info for local var declaration.
if (HaveInsertPoint())
if (CGDebugInfo *DI = getDebugInfo()) {
if (CGM.getCodeGenOpts().getDebugInfo() >=
codegenoptions::LimitedDebugInfo) {
DI->EmitDeclareOfAutoVariable(&D, address.getPointer(), Builder);
if (D.hasAttr<AnnotateAttr>())
EmitVarAnnotations(&D, address.getPointer());
return emission;
/// 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 *E = dyn_cast<Expr>(BI)) {
if (isCapturedBy(var, E))
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, cast<Expr>(SubStmt)))
return true;
return false;
/// \brief 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::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.IsByRef)
if (isTrivialInitializer(Init))
// 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 = emission.IsByRef && isCapturedBy(D, Init);
Address Loc =
capturedByInit ? emission.Addr : emission.getObjectAddress(*this);
llvm::Constant *constant = nullptr;
if (emission.IsConstantAggregate || D.isConstexpr()) {
assert(!capturedByInit && "constant init contains a capturing block?");
constant = CGM.EmitConstantInit(D, this);
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);
// If this is a simple aggregate initialization, we can optimize it
// in various ways.
bool isVolatile = type.isVolatileQualified();
llvm::Value *SizeVal =
llvm::Type *BP = Int8PtrTy;
if (Loc.getType() != BP)
Loc = Builder.CreateBitCast(Loc, BP);
// If the initializer is all or mostly zeros, codegen with memset then do
// a few stores afterward.
if (shouldUseMemSetPlusStoresToInitialize(constant,
CGM.getDataLayout().getTypeAllocSize(constant->getType()))) {
Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, 0), SizeVal,
// Zero and undef don't require a stores.
if (!constant->isNullValue() && !isa<llvm::UndefValue>(constant)) {
Loc = Builder.CreateBitCast(Loc, constant->getType()->getPointerTo());
emitStoresForInitAfterMemset(constant, Loc.getPointer(),
isVolatile, Builder);
} else {
// Otherwise, create a temporary global with the initializer then
// memcpy from the global to the alloca.
std::string Name = getStaticDeclName(CGM, D);
unsigned AS = 0;
if (getLangOpts().OpenCL) {
AS = CGM.getContext().getTargetAddressSpace(LangAS::opencl_constant);
BP = llvm::PointerType::getInt8PtrTy(getLLVMContext(), AS);
llvm::GlobalVariable *GV =
new llvm::GlobalVariable(CGM.getModule(), constant->getType(), true,
constant, Name, nullptr,
llvm::GlobalValue::NotThreadLocal, AS);
Address SrcPtr = Address(GV, Loc.getAlignment());
if (SrcPtr.getType() != BP)
SrcPtr = Builder.CreateBitCast(SrcPtr, BP);
Builder.CreateMemCpy(Loc, SrcPtr, SizeVal, isVolatile);
/// Emit an expression as an initializer for a variable at the given
/// location. The expression is not necessarily the normal
/// initializer for the variable, and the address is not necessarily
/// its normal location.
/// \param init the initializing expression
/// \param var the variable to act as if we're initializing
/// \param loc the address to initialize; its type is a pointer
/// to the LLVM mapping of the variable's type
/// \param alignment the alignment of the address
/// \param capturedByInit true if the variable 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 {
// TODO: how can we delay here if D is captured by its initializer?
EmitAggExpr(init, AggValueSlot::forLValue(lvalue,
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<DestroyNRVOVariable>(cleanupKind, addr,
dtor, emission.NRVOFlag);
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:
// 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;
// Make sure we call @llvm.lifetime.end. This needs to happen
// *last*, so the cleanup needs to be pushed *first*.
if (emission.useLifetimeMarkers())
// Check the type for a cleanup.
if (QualType::DestructionKind dtorKind = D.getType().isDestructedType())
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).
if (emission.IsByRef)
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;
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) {
assert(!isInConditionalBranch() &&
"performing lifetime extension from within conditional");
// 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);
// Remember that we need to push a full cleanup for the object at the
// end of the full-expression.
cleanupKind, addr, type, destroyer, useEHCleanupForArray);
/// 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(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, 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);
begin = CGF.Builder.CreateInBoundsGEP(begin, gepIndices, "pad.arraybegin");
end = CGF.Builder.CreateInBoundsGEP(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::Constant *CodeGenModule::getLLVMLifetimeStartFn() {
if (LifetimeStartFn) return LifetimeStartFn;
LifetimeStartFn = llvm::Intrinsic::getDeclaration(&getModule(),
return LifetimeStartFn;
/// Lazily declare the @llvm.lifetime.end intrinsic.
llvm::Constant *CodeGenModule::getLLVMLifetimeEndFn() {
if (LifetimeEndFn) return LifetimeEndFn;
LifetimeEndFn = llvm::Intrinsic::getDeclaration(&getModule(),
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);
} // end anonymous namespace
/// Emit an alloca (or GlobalValue depending on target)
/// for the specified parameter and set up LocalDeclMap.
void CodeGenFunction::EmitParmDecl(const VarDecl &D, ParamValue Arg,
unsigned ArgNo) {
// FIXME: Why isn't ImplicitParamDecl a ParmVarDecl?
assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) &&
"Invalid argument to EmitParmDecl");
QualType Ty = D.getType();
// Use better IR generation for certain implicit parameters.
if (auto IPD = dyn_cast<ImplicitParamDecl>(&D)) {
// The only implicit argument a block has is its literal.
// We assume this is always passed directly.
if (BlockInfo) {
setBlockContextParameter(IPD, ArgNo, Arg.getDirectValue());
// Apply any prologue 'this' adjustments required by the ABI. Be careful to
// handle the case where 'this' is passed indirectly as part of an inalloca
// struct.
if (const CXXMethodDecl *MD =
dyn_cast_or_null<CXXMethodDecl>(CurCodeDecl)) {
if (MD->isVirtual() && IPD == CXXABIThisDecl) {
llvm::Value *This = Arg.isIndirect()
? Builder.CreateLoad(Arg.getIndirectAddress())
: Arg.getDirectValue();
This = CGM.getCXXABI().adjustThisParameterInVirtualFunctionPrologue(
*this, CurGD, This);
if (Arg.isIndirect())
Builder.CreateStore(This, Arg.getIndirectAddress());
Arg = ParamValue::forDirect(This);
Address DeclPtr = Address::invalid();
bool DoStore = false;
bool IsScalar = hasScalarEvaluationKind(Ty);
// If we already have a pointer to the argument, reuse the input pointer.
if (Arg.isIndirect()) {
DeclPtr = Arg.getIndirectAddress();
// If we have a prettier pointer type at this point, bitcast to that.
unsigned AS = DeclPtr.getType()->getAddressSpace();
llvm::Type *IRTy = ConvertTypeForMem(Ty)->getPointerTo(AS);
if (DeclPtr.getType() != IRTy)
DeclPtr = Builder.CreateBitCast(DeclPtr, IRTy, D.getName());
// Push a destructor cleanup for this parameter if the ABI requires it.
// Don't push a cleanup in a thunk for a method that will also emit a
// cleanup.
if (!IsScalar && !CurFuncIsThunk &&
getTarget().getCXXABI().areArgsDestroyedLeftToRightInCallee()) {
const CXXRecordDecl *RD = Ty->getAsCXXRecordDecl();
if (RD && RD->hasNonTrivialDestructor())
pushDestroy(QualType::DK_cxx_destructor, DeclPtr, Ty);
} else {
// Otherwise, create a temporary to hold the value.
DeclPtr = CreateMemTemp(Ty, getContext().getDeclAlign(&D),
D.getName() + ".addr");
DoStore = true;
llvm::Value *ArgVal = (DoStore ? Arg.getDirectValue() : nullptr);
LValue lv = MakeAddrLValue(DeclPtr, Ty);
if (IsScalar) {
Qualifiers qs = Ty.getQualifiers();
if (Qualifiers::ObjCLifetime lt = qs.getObjCLifetime()) {
// We honor __attribute__((ns_consumed)) for types with lifetime.
// For __strong, it's handled by just skipping the initial retain;
// otherwise we have to balance out the initial +1 with an extra
// cleanup to do the release at the end of the function.
bool isConsumed = D.hasAttr<NSConsumedAttr>();
// 'self' is always formally __strong, but if this is not an
// init method then we don't want to retain it.
if (D.isARCPseudoStrong()) {
const ObjCMethodDecl *method = cast<ObjCMethodDecl>(CurCodeDecl);
assert(&D == method->getSelfDecl());
assert(lt == Qualifiers::OCL_Strong);
assert(method->getMethodFamily() != OMF_init);
(void) method;
lt = Qualifiers::OCL_ExplicitNone;
if (lt == Qualifiers::OCL_Strong) {
if (!isConsumed) {
if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
// use objc_storeStrong(&dest, value) for retaining the
// object. But first, store a null into 'dest' because
// objc_storeStrong attempts to release its old value.
llvm::Value *Null = CGM.EmitNullConstant(D.getType());
EmitStoreOfScalar(Null, lv, /* isInitialization */ true);
EmitARCStoreStrongCall(lv.getAddress(), ArgVal, true);
DoStore = false;
// Don't use objc_retainBlock for block pointers, because we
// don't want to Block_copy something just because we got it
// as a parameter.
ArgVal = EmitARCRetainNonBlock(ArgVal);
} else {
// Push the cleanup for a consumed parameter.
if (isConsumed) {
ARCPreciseLifetime_t precise = (D.hasAttr<ObjCPreciseLifetimeAttr>()
? ARCPreciseLifetime : ARCImpreciseLifetime);
EHStack.pushCleanup<ConsumeARCParameter>(getARCCleanupKind(), ArgVal,
if (lt == Qualifiers::OCL_Weak) {
EmitARCInitWeak(DeclPtr, ArgVal);
DoStore = false; // The weak init is a store, no need to do two.
// Enter the cleanup scope.
EmitAutoVarWithLifetime(*this, D, DeclPtr, lt);
// Store the initial value into the alloca.
if (DoStore)
EmitStoreOfScalar(ArgVal, lv, /* isInitialization */ true);
setAddrOfLocalVar(&D, DeclPtr);
// Emit debug info for param declaration.
if (CGDebugInfo *DI = getDebugInfo()) {
if (CGM.getCodeGenOpts().getDebugInfo() >=
codegenoptions::LimitedDebugInfo) {
DI->EmitDeclareOfArgVariable(&D, DeclPtr.getPointer(), ArgNo, Builder);
if (D.hasAttr<AnnotateAttr>())
EmitVarAnnotations(&D, DeclPtr.getPointer());
void CodeGenModule::EmitOMPDeclareReduction(const OMPDeclareReductionDecl *D,
CodeGenFunction *CGF) {
if (!LangOpts.OpenMP || (!LangOpts.EmitAllDecls && !D->isUsed()))
getOpenMPRuntime().emitUserDefinedReduction(CGF, D);