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1//===--- CGDeclCXX.cpp - Emit LLVM Code for C++ declarations --------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8//9// This contains code dealing with code generation of C++ declarations10//11//===----------------------------------------------------------------------===//12}68/// Emit code to cause the destruction of the given variable with70/// static storage duration.71static void EmitDeclDestroy(CodeGenFunction &CGF, const VarDecl &D,72ConstantAddress Addr) {73// Honor __attribute__((no_destroy)) and bail instead of attempting74// to emit a reference to a possibly nonexistent destructor, which75// in turn can cause a crash. This will result in a global constructor76// that isn't balanced out by a destructor call as intended by the77// attribute. This also checks for -fno-c++-static-destructors and78// bails even if the attribute is not present.79QualType::DestructionKind DtorKind = D.needsDestruction(CGF.getContext());80}148/// Emit code to cause the variable at the given address to be considered as150/// constant from this point onwards.151static void EmitDeclInvariant(CodeGenFunction &CGF, const VarDecl &D,152llvm::Constant *Addr) {153return CGF.EmitInvariantStart(154Addr, CGF.getContext().getTypeSizeInChars(D.getType()));155}156}174}232/// Create a stub function, suitable for being passed to atexit,234/// which passes the given address to the given destructor function.235llvm::Function *CodeGenFunction::createAtExitStub(const VarDecl &VD,236llvm::FunctionCallee dtor,237llvm::Constant *addr) {238// Get the destructor function type, void(*)(void).239llvm::FunctionType *ty = llvm::FunctionType::get(CGM.VoidTy, false);240SmallString<256> FnName;241{242llvm::raw_svector_ostream Out(FnName);243CGM.getCXXABI().getMangleContext().mangleDynamicAtExitDestructor(&VD, Out);244}245}269/// Create a stub function, suitable for being passed to __pt_atexit_np,271/// which passes the given address to the given destructor function.272llvm::Function *CodeGenFunction::createTLSAtExitStub(273const VarDecl &D, llvm::FunctionCallee Dtor, llvm::Constant *Addr,274llvm::FunctionCallee &AtExit) {275SmallString<256> FnName;276{277llvm::raw_svector_ostream Out(FnName);278CGM.getCXXABI().getMangleContext().mangleDynamicAtExitDestructor(&D, Out);279}280}321/// Register a global destructor using the C atexit runtime function.323void CodeGenFunction::registerGlobalDtorWithAtExit(const VarDecl &VD,324llvm::FunctionCallee dtor,325llvm::Constant *addr) {326// Create a function which calls the destructor.327llvm::Constant *dtorStub = createAtExitStub(VD, dtor, addr);328registerGlobalDtorWithAtExit(dtorStub);329}330/// Register a global destructor using the LLVM 'llvm.global_dtors' global.332void CodeGenFunction::registerGlobalDtorWithLLVM(const VarDecl &VD,333llvm::FunctionCallee Dtor,334llvm::Constant *Addr) {335// Create a function which calls the destructor.336llvm::Function *dtorStub = createAtExitStub(VD, Dtor, Addr);337CGM.AddGlobalDtor(dtorStub);338}339}359}385}399}436}502/// Create a global pointer to a function that will initialize a global504/// variable. The user has requested that this pointer be emitted in a specific505/// section.506void CodeGenModule::EmitPointerToInitFunc(const VarDecl *D,507llvm::GlobalVariable *GV,508llvm::Function *InitFunc,509InitSegAttr *ISA) {510llvm::GlobalVariable *PtrArray = new llvm::GlobalVariable(511TheModule, InitFunc->getType(), /*isConstant=*/true,512llvm::GlobalValue::PrivateLinkage, InitFunc, "__cxx_init_fn_ptr");513PtrArray->setSection(ISA->getSection());514addUsedGlobal(PtrArray);515}520void522CodeGenModule::EmitCXXGlobalVarDeclInitFunc(const VarDecl *D,523llvm::GlobalVariable *Addr,524bool PerformInit) {525}641}650/* Build the initializer for a C++20 module:652This is arranged to be run only once regardless of how many times the module653might be included transitively. This arranged by using a guard variable.654If there are no initializers at all (and also no imported modules) we reduce656this to an empty function (since the Itanium ABI requires that this function657be available to a caller, which might be produced by a different658implementation).659First we call any initializers for imported modules.661We then call initializers for the Global Module Fragment (if present)662We then call initializers for the current module.663We then call initializers for the Private Module Fragment (if present)664*/665}803}819}830void832CodeGenModule::EmitCXXGlobalInitFunc() {833while (!CXXGlobalInits.empty() && !CXXGlobalInits.back())834CXXGlobalInits.pop_back();835}957}1012/// Emit the code necessary to initialize the given global variable.1014void CodeGenFunction::GenerateCXXGlobalVarDeclInitFunc(llvm::Function *Fn,1015const VarDecl *D,1016llvm::GlobalVariable *Addr,1017bool PerformInit) {1018// Check if we need to emit debug info for variable initializer.1019if (D->hasAttr<NoDebugAttr>())1020DebugInfo = nullptr; // disable debug info indefinitely for this function1021}1050void1052CodeGenFunction::GenerateCXXGlobalInitFunc(llvm::Function *Fn,1053ArrayRef<llvm::Function *> Decls,1054ConstantAddress Guard) {1055{1056auto NL = ApplyDebugLocation::CreateEmpty(*this);1057StartFunction(GlobalDecl(), getContext().VoidTy, Fn,1058getTypes().arrangeNullaryFunction(), FunctionArgList());1059// Emit an artificial location for this function.1060auto AL = ApplyDebugLocation::CreateArtificial(*this);1061}1109}1146/// generateDestroyHelper - Generates a helper function which, when1148/// invoked, destroys the given object. The address of the object1149/// should be in global memory.1150llvm::Function *CodeGenFunction::generateDestroyHelper(1151Address addr, QualType type, Destroyer *destroyer,1152bool useEHCleanupForArray, const VarDecl *VD) {1153FunctionArgList args;1154ImplicitParamDecl Dst(getContext(), getContext().VoidPtrTy,1155ImplicitParamKind::Other);1156args.push_back(&Dst);1157}1177