//===--- 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 "CGBlocks.h" #include "CGCXXABI.h" #include "CGCleanup.h" #include "CGDebugInfo.h" #include "CGOpenCLRuntime.h" #include "CGOpenMPRuntime.h" #include "CodeGenFunction.h" #include "CodeGenModule.h" #include "TargetInfo.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::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: 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. return; case Decl::NamespaceAlias: if (CGDebugInfo *DI = getDebugInfo()) DI->EmitNamespaceAlias(cast(D)); return; case Decl::Using: // using X; [C++] if (CGDebugInfo *DI = getDebugInfo()) DI->EmitUsingDecl(cast(D)); return; case Decl::UsingPack: for (auto *Using : cast(D).expansions()) EmitDecl(*Using); return; case Decl::UsingDirective: // using namespace X; [C++] if (CGDebugInfo *DI = getDebugInfo()) DI->EmitUsingDirective(cast(D)); return; case Decl::Var: case Decl::Decomposition: { const VarDecl &VD = cast(D); assert(VD.isLocalVarDecl() && "Should not see file-scope variables inside a function!"); EmitVarDecl(VD); if (auto *DD = dyn_cast(&VD)) for (auto *B : DD->bindings()) if (auto *HD = B->getHoldingVar()) EmitVarDecl(*HD); return; } case Decl::OMPDeclareReduction: return CGM.EmitOMPDeclareReduction(cast(&D), this); case Decl::Typedef: // typedef int X; case Decl::TypeAlias: { // using X = int; [C++0x] const TypedefNameDecl &TD = cast(D); QualType Ty = TD.getUnderlyingType(); if (Ty->isVariablyModifiedType()) EmitVariablyModifiedType(Ty); } } } /// 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. return; // 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) { 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); assert(D.hasLocalStorage()); 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(DC)) DC = cast(CD->getNonClosureContext()); if (const auto *FD = dyn_cast(DC)) ContextName = CGM.getMangledName(FD); else if (const auto *BD = dyn_cast(DC)) ContextName = CGM.getBlockMangledName(GlobalDecl(), BD); else if (const auto *OMD = dyn_cast(DC)) ContextName = OMD->getSelector().getAsString(); else 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()) Name = getMangledName(&D); else Name = getStaticDeclName(*this, D); llvm::Type *LTy = getTypes().ConvertTypeForMem(Ty); unsigned AS = GetGlobalVarAddressSpace(&D); unsigned TargetAS = getContext().getTargetAddressSpace(AS); // Local address space cannot have an initializer. llvm::Constant *Init = nullptr; if (Ty.getAddressSpace() != LangAS::opencl_local) Init = EmitNullConstant(Ty); else Init = llvm::UndefValue::get(LTy); llvm::GlobalVariable *GV = new llvm::GlobalVariable( getModule(), LTy, Ty.isConstant(getContext()), Linkage, Init, Name, nullptr, llvm::GlobalVariable::NotThreadLocal, TargetAS); GV->setAlignment(getContext().getDeclAlign(&D).getQuantity()); setGlobalVisibility(GV, &D); if (supportsCOMDAT() && GV->isWeakForLinker()) GV->setComdat(TheModule.getOrInsertComdat(GV->getName())); if (D.getTLSKind()) setTLSMode(GV, D); if (D.isExternallyVisible()) { if (D.hasAttr()) GV->setDLLStorageClass(llvm::GlobalVariable::DLLImportStorageClass); else if (D.hasAttr()) GV->setDLLStorageClass(llvm::GlobalVariable::DLLExportStorageClass); } // Make sure the result is of the correct type. unsigned ExpectedAS = Ty.getAddressSpace(); llvm::Constant *Addr = GV; if (AS != ExpectedAS) { Addr = getTargetCodeGenInfo().performAddrSpaceCast( *this, GV, AS, ExpectedAS, LTy->getPointerTo(getContext().getTargetAddressSpace(ExpectedAS))); } setStaticLocalDeclAddress(&D, Addr); // Ensure that the static local gets initialized by making sure the parent // function gets emitted eventually. const Decl *DC = cast(D.getDeclContext()); // We can't name blocks or captured statements directly, so try to emit their // parents. if (isa(DC) || isa(DC)) { DC = DC->getNonClosureContext(); // FIXME: Ensure that global blocks get emitted. if (!DC) return Addr; } GlobalDecl GD; if (const auto *CD = dyn_cast(DC)) GD = GlobalDecl(CD, Ctor_Base); else if (const auto *DD = dyn_cast(DC)) GD = GlobalDecl(DD, Dtor_Base); else if (const auto *FD = dyn_cast(DC)) GD = GlobalDecl(FD); else { // Don't do anything for Obj-C method decls or global closures. We should // never defer them. assert(isa(DC) && "unexpected parent code decl"); } if (GD.getDecl()) (void)GetAddrOfGlobal(GD); 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. GV->setConstant(false); 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->isConstant(), OldGV->getLinkage(), Init, "", /*InsertBefore*/ OldGV, OldGV->getThreadLocalMode(), CGM.getContext().getTargetAddressSpace(D.getType())); GV->setVisibility(OldGV->getVisibility()); GV->setComdat(OldGV->getComdat()); // Steal the name of the old global GV->takeName(OldGV); // Replace all uses of the old global with the new global llvm::Constant *NewPtrForOldDecl = llvm::ConstantExpr::getBitCast(GV, OldGV->getType()); OldGV->replaceAllUsesWith(NewPtrForOldDecl); // Erase the old global, since it is no longer used. OldGV->eraseFromParent(); } GV->setConstant(CGM.isTypeConstant(D.getType(), true)); GV->setInitializer(Init); 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()) EmitVariablyModifiedType(D.getType()); // Save the type in case adding the initializer forces a type change. llvm::Type *expectedType = addr->getType(); llvm::GlobalVariable *var = cast(addr->stripPointerCasts()); // 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 && D.hasAttr(); // If this value has an initializer, emit it. if (D.getInit() && !isCudaSharedVar) var = AddInitializerToStaticVarDecl(D, var); var->setAlignment(alignment.getQuantity()); if (D.hasAttr()) CGM.AddGlobalAnnotations(&D, var); if (auto *SA = D.getAttr()) var->addAttribute("bss-section", SA->getName()); if (auto *SA = D.getAttr()) var->addAttribute("data-section", SA->getName()); if (auto *SA = D.getAttr()) var->addAttribute("rodata-section", SA->getName()); if (const SectionAttr *SA = D.getAttr()) var->setSection(SA->getName()); if (D.hasAttr()) CGM.addUsedGlobal(var); // 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->setLocation(D.getLocation()); 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.EmitBlock(RunDtorBB); } CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete, /*ForVirtualBase=*/false, /*Delegating=*/false, Loc); 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(&Var), false, Var.getType(), VK_LValue, SourceLocation()); llvm::Value *value = CGF.EmitLoadOfScalar(CGF.EmitDeclRefLValue(&DRE), SourceLocation()); CGF.EmitExtendGCLifetime(value); } }; 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(&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; Args.add(RValue::get(Arg), CGF.getContext().getPointerType(Var.getType())); 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 break; case Qualifiers::OCL_Strong: { CodeGenFunction::Destroyer *destroyer = (var.hasAttr() ? CodeGenFunction::destroyARCStrongPrecise : CodeGenFunction::destroyARCStrongImprecise); CleanupKind cleanupKind = CGF.getARCCleanupKind(); CGF.pushDestroy(cleanupKind, addr, var.getType(), destroyer, cleanupKind & EHCleanup); break; } case Qualifiers::OCL_Autoreleasing: // nothing to do break; 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(), CodeGenFunction::destroyARCWeak, /*useEHCleanup*/ true); break; } } static bool isAccessedBy(const VarDecl &var, const Stmt *s) { if (const Expr *e = dyn_cast(s)) { // Skip the most common kinds of expressions that make // hierarchy-walking expensive. s = e = e->IgnoreParenCasts(); if (const DeclRefExpr *ref = dyn_cast(e)) return (ref->getDecl() == &var); if (const BlockExpr *be = dyn_cast(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(decl)) return false; const VarDecl *var = cast(decl); return isAccessedBy(*var, e); } static bool tryEmitARCCopyWeakInit(CodeGenFunction &CGF, const LValue &destLV, const Expr *init) { bool needsCast = false; while (auto castExpr = dyn_cast(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; break; // 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, destLV.getAddress().getElementType()); } // 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. default: 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::EmitNullabilityCheck(LValue LHS, llvm::Value *RHS, SourceLocation Loc) { if (!SanOpts.has(SanitizerKind::NullabilityAssign)) return; auto Nullability = LHS.getType()->getNullability(getContext()); if (!Nullability || *Nullability != NullabilityKind::NonNull) return; // 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(D)); EmitNullabilityCheck(lvalue, value, init->getExprLoc()); EmitStoreThroughLValue(RValue::get(value), lvalue, true); return; } if (const CXXDefaultInitExpr *DIE = dyn_cast(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(init)) { enterFullExpression(ewc); 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. tempLV.setAddress(emitBlockByrefAddress(tempLV.getAddress(), cast(D), /*follow*/ false)); } auto ty = cast(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. else 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); break; case Qualifiers::OCL_Strong: { value = EmitARCRetainScalarExpr(init); break; } 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)) { return; } // 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(D)); if (accessedByInit) EmitARCStoreWeak(lvalue.getAddress(), value, /*ignored*/ true); else EmitARCInitWeak(lvalue.getAddress(), value); return; } case Qualifiers::OCL_Autoreleasing: value = EmitARCRetainAutoreleaseScalarExpr(init); break; } if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast(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); return; } 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(Init) || isa(Init) || isa(Init)) return true; if (isa(Init) || isa(Init) || isa(Init) || isa(Init) || isa(Init)) return Init->isNullValue() || NumStores--; // See if we can emit each element. if (isa(Init) || isa(Init)) { for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) { llvm::Constant *Elt = cast(Init->getOperand(i)); if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores)) return false; } return true; } if (llvm::ConstantDataSequential *CDS = dyn_cast(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(Init) && "called emitStoresForInitAfterMemset for zero or undef value."); if (isa(Init) || isa(Init) || isa(Init) || isa(Init) || isa(Init)) { Builder.CreateDefaultAlignedStore(Init, Loc, isVolatile); return; } if (llvm::ConstantDataSequential *CDS = dyn_cast(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(Elt)) emitStoresForInitAfterMemset( Elt, Builder.CreateConstGEP2_32(Init->getType(), Loc, 0, i), isVolatile, Builder); } return; } assert((isa(Init) || isa(Init)) && "Unknown value type!"); for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) { llvm::Constant *Elt = cast(Init->getOperand(i)); // If necessary, get a pointer to the element and emit it. if (!Elt->isNullValue() && !isa(Elt)) emitStoresForInitAfterMemset( 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(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); EmitAutoVarInit(emission); EmitAutoVarCleanups(emission); } /// 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, AllocaInt8PtrTy); llvm::CallInst *C = Builder.CreateCall(CGM.getLLVMLifetimeStartFn(), {SizeV, Addr}); C->setDoesNotThrow(); return SizeV; } void CodeGenFunction::EmitLifetimeEnd(llvm::Value *Size, llvm::Value *Addr) { Addr = Builder.CreateBitCast(Addr, AllocaInt8PtrTy); llvm::CallInst *C = Builder.CreateCall(CGM.getLLVMLifetimeEndFn(), {Size, Addr}); C->setDoesNotThrow(); } /// EmitAutoVarAlloca - Emit the alloca and debug information for a /// local variable. Does not emit initialization or destruction. CodeGenFunction::AutoVarEmission CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) { QualType Ty = D.getType(); assert(Ty.getAddressSpace() == LangAS::Default); AutoVarEmission emission(D); bool isByRef = D.hasAttr(); emission.IsByRef = isByRef; CharUnits alignment = getContext().getDeclAlign(&D); // If the type is variably-modified, emit all the VLA sizes for it. if (Ty->isVariablyModifiedType()) EmitVariablyModifiedType(Ty); Address address = Address::invalid(); if (Ty->isConstantSizeType()) { bool NRVO = getLangOpts().ElideConstructors && D.isNRVOVariable(); // 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(); assert(emission.wasEmittedAsGlobal()); 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()) { if (!cast(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"); EnsureInsertPoint(); 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, D.getName()); // 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())) { uint64_t size = CGM.getDataLayout().getTypeAllocSize(allocaTy); emission.SizeForLifetimeMarkers = EmitLifetimeStart(size, address.getPointer()); } } else { assert(!emission.useLifetimeMarkers()); } } } else { EnsureInsertPoint(); 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. address = CreateTempAlloca(llvmTy, alignment, "vla", elementCount); } 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->setLocation(D.getLocation()); DI->EmitDeclareOfAutoVariable(&D, address.getPointer(), Builder); } } if (D.hasAttr()) EmitVarAnnotations(&D, address.getPointer()); // Make sure we call @llvm.lifetime.end. if (emission.useLifetimeMarkers()) EHStack.pushCleanup(NormalEHLifetimeMarker, emission.getAllocatedAddress(), emission.getSizeForLifetimeMarkers()); 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(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(e)) { const CompoundStmt *CS = SE->getSubStmt(); for (const auto *BI : CS->body()) if (const auto *E = dyn_cast(BI)) { if (isCapturedBy(var, E)) return true; } else if (const auto *DS = dyn_cast(BI)) { // special case declarations for (const auto *I : DS->decls()) { if (const auto *VD = dyn_cast((I))) { const Expr *Init = VD->getInit(); if (Init && isCapturedBy(var, Init)) return true; } } } else // 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(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(Init)) if (CXXConstructorDecl *Constructor = Construct->getConstructor()) if (Constructor->isTrivial() && Constructor->isDefaultConstructor() && !Construct->requiresZeroInitialization()) 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; EnsureInsertPoint(); } // Initialize the structure of a __block variable. if (emission.IsByRef) emitByrefStructureInit(emission); if (isTrivialInitializer(Init)) return; // 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); lv.setNonGC(true); return EmitExprAsInit(Init, &D, lv, capturedByInit); } if (!emission.IsConstantAggregate) { // For simple scalar/complex initialization, store the value directly. LValue lv = MakeAddrLValue(Loc, type); lv.setNonGC(true); 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::ConstantInt::get(IntPtrTy, getContext().getTypeSizeInChars(type).getQuantity()); 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, isVolatile); // Zero and undef don't require a stores. if (!constant->isNullValue() && !isa(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, llvm::GlobalValue::PrivateLinkage, constant, Name, nullptr, llvm::GlobalValue::NotThreadLocal, AS); GV->setAlignment(Loc.getAlignment().getQuantity()); GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global); 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(D)); EmitStoreThroughLValue(rvalue, lvalue, true); return; } switch (getEvaluationKind(type)) { case TEK_Scalar: EmitScalarInit(init, D, lvalue, capturedByInit); return; case TEK_Complex: { ComplexPairTy complex = EmitComplexExpr(init); if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast(D)); EmitStoreOfComplex(complex, lvalue, /*init*/ true); return; } case TEK_Aggregate: if (type->isAtomicType()) { EmitAtomicInit(const_cast(init), lvalue); } else { // TODO: how can we delay here if D is captured by its initializer? EmitAggExpr(init, AggValueSlot::forLValue(lvalue, AggValueSlot::IsDestructed, AggValueSlot::DoesNotNeedGCBarriers, AggValueSlot::IsNotAliased)); } return; } 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) { assert(!type->isArrayType()); CXXDestructorDecl *dtor = type->getAsCXXRecordDecl()->getDestructor(); EHStack.pushCleanup(cleanupKind, addr, dtor, emission.NRVOFlag); return; } break; 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()) destroyer = CodeGenFunction::destroyARCStrongImprecise; break; case QualType::DK_objc_weak_lifetime: break; } // 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(cleanupKind, addr, type, destroyer, useEHCleanup); } 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.getType().isDestructedType()) emitAutoVarTypeCleanup(emission, dtorKind); // In GC mode, honor objc_precise_lifetime. if (getLangOpts().getGC() != LangOptions::NonGC && D.hasAttr()) { EHStack.pushCleanup(NormalCleanup, &D); } // Handle the cleanup attribute. if (const CleanupAttr *CA = D.getAttr()) { 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(NormalAndEHCleanup, F, &Info, &D); } // If this is a block variable, call _Block_object_destroy // (on the unforwarded address). if (emission.IsByRef) enterByrefCleanup(emission); } 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"); assert(needsEHCleanup(dtorKind)); 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(cleanupKind, addr, type, destroyer, useEHCleanupForArray); } void CodeGenFunction::pushStackRestore(CleanupKind Kind, Address SPMem) { EHStack.pushCleanup(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) EHStack.pushCleanup( static_cast(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. pushCleanupAfterFullExpr( 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 = addr.getAlignment() .alignmentOfArrayElement(getContext().getTypeSizeInChars(type)); // 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(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) { assert(!elementType->isArrayType()); // 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, "arraydestroy.isempty"); Builder.CreateCondBr(isEmpty, doneBB, bodyBB); } // Enter the loop body, making that address the current address. llvm::BasicBlock *entryBB = Builder.GetInsertBlock(); EmitBlock(bodyBB); 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, "arraydestroy.element"); if (useEHCleanup) pushRegularPartialArrayCleanup(begin, element, elementType, elementAlign, destroyer); // Perform the actual destruction there. destroyer(*this, Address(element, elementAlign), elementType); if (useEHCleanup) PopCleanupBlock(); // 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. EmitBlock(doneBB); } /// 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(arrayType)) arrayDepth++; type = arrayType->getElementType(); } if (arrayDepth) { llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, 0); SmallVector 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; public: 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; public: 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) { pushFullExprCleanup(EHCleanup, arrayBegin, arrayEndPointer, elementType, elementAlign, destroyer); } /// 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) { pushFullExprCleanup(EHCleanup, arrayBegin, arrayEnd, elementType, elementAlign, destroyer); } /// Lazily declare the @llvm.lifetime.start intrinsic. llvm::Constant *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::Constant *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); } }; } // 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(D) || isa(D)) && "Invalid argument to EmitParmDecl"); Arg.getAnyValue()->setName(D.getName()); QualType Ty = D.getType(); // Use better IR generation for certain implicit parameters. if (auto IPD = dyn_cast(&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()); return; } // 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(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()); else 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(); // '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(CurCodeDecl); assert(&D == method->getSelfDecl()); assert(lt == Qualifiers::OCL_Strong); assert(qs.hasConst()); assert(method->getMethodFamily() != OMF_init); (void) method; lt = Qualifiers::OCL_ExplicitNone; } // Load objects passed indirectly. if (Arg.isIndirect() && !ArgVal) ArgVal = Builder.CreateLoad(DeclPtr); 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; } else // 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() ? ARCPreciseLifetime : ARCImpreciseLifetime); EHStack.pushCleanup(getARCCleanupKind(), ArgVal, precise); } 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()) EmitVarAnnotations(&D, DeclPtr.getPointer()); // We can only check return value nullability if all arguments to the // function satisfy their nullability preconditions. This makes it necessary // to emit null checks for args in the function body itself. if (requiresReturnValueNullabilityCheck()) { auto Nullability = Ty->getNullability(getContext()); if (Nullability && *Nullability == NullabilityKind::NonNull) { SanitizerScope SanScope(this); RetValNullabilityPrecondition = Builder.CreateAnd(RetValNullabilityPrecondition, Builder.CreateIsNotNull(Arg.getAnyValue())); } } } void CodeGenModule::EmitOMPDeclareReduction(const OMPDeclareReductionDecl *D, CodeGenFunction *CGF) { if (!LangOpts.OpenMP || (!LangOpts.EmitAllDecls && !D->isUsed())) return; getOpenMPRuntime().emitUserDefinedReduction(CGF, D); }