| //===--- CGDeclCXX.cpp - Emit LLVM Code for C++ 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 dealing with code generation of C++ declarations |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "CodeGenFunction.h" |
| #include "CGCXXABI.h" |
| #include "CGObjCRuntime.h" |
| #include "clang/Frontend/CodeGenOptions.h" |
| #include "llvm/ADT/StringExtras.h" |
| #include "llvm/IR/Intrinsics.h" |
| |
| using namespace clang; |
| using namespace CodeGen; |
| |
| static void EmitDeclInit(CodeGenFunction &CGF, const VarDecl &D, |
| llvm::Constant *DeclPtr) { |
| assert(D.hasGlobalStorage() && "VarDecl must have global storage!"); |
| assert(!D.getType()->isReferenceType() && |
| "Should not call EmitDeclInit on a reference!"); |
| |
| ASTContext &Context = CGF.getContext(); |
| |
| CharUnits alignment = Context.getDeclAlign(&D); |
| QualType type = D.getType(); |
| LValue lv = CGF.MakeAddrLValue(DeclPtr, type, alignment); |
| |
| const Expr *Init = D.getInit(); |
| switch (CGF.getEvaluationKind(type)) { |
| case TEK_Scalar: { |
| CodeGenModule &CGM = CGF.CGM; |
| if (lv.isObjCStrong()) |
| CGM.getObjCRuntime().EmitObjCGlobalAssign(CGF, CGF.EmitScalarExpr(Init), |
| DeclPtr, D.getTLSKind()); |
| else if (lv.isObjCWeak()) |
| CGM.getObjCRuntime().EmitObjCWeakAssign(CGF, CGF.EmitScalarExpr(Init), |
| DeclPtr); |
| else |
| CGF.EmitScalarInit(Init, &D, lv, false); |
| return; |
| } |
| case TEK_Complex: |
| CGF.EmitComplexExprIntoLValue(Init, lv, /*isInit*/ true); |
| return; |
| case TEK_Aggregate: |
| CGF.EmitAggExpr(Init, AggValueSlot::forLValue(lv,AggValueSlot::IsDestructed, |
| AggValueSlot::DoesNotNeedGCBarriers, |
| AggValueSlot::IsNotAliased)); |
| return; |
| } |
| llvm_unreachable("bad evaluation kind"); |
| } |
| |
| /// Emit code to cause the destruction of the given variable with |
| /// static storage duration. |
| static void EmitDeclDestroy(CodeGenFunction &CGF, const VarDecl &D, |
| llvm::Constant *addr) { |
| CodeGenModule &CGM = CGF.CGM; |
| |
| // FIXME: __attribute__((cleanup)) ? |
| |
| QualType type = D.getType(); |
| QualType::DestructionKind dtorKind = type.isDestructedType(); |
| |
| switch (dtorKind) { |
| case QualType::DK_none: |
| return; |
| |
| case QualType::DK_cxx_destructor: |
| break; |
| |
| case QualType::DK_objc_strong_lifetime: |
| case QualType::DK_objc_weak_lifetime: |
| // We don't care about releasing objects during process teardown. |
| assert(!D.getTLSKind() && "should have rejected this"); |
| return; |
| } |
| |
| llvm::Constant *function; |
| llvm::Constant *argument; |
| |
| // Special-case non-array C++ destructors, where there's a function |
| // with the right signature that we can just call. |
| const CXXRecordDecl *record = 0; |
| if (dtorKind == QualType::DK_cxx_destructor && |
| (record = type->getAsCXXRecordDecl())) { |
| assert(!record->hasTrivialDestructor()); |
| CXXDestructorDecl *dtor = record->getDestructor(); |
| |
| function = CGM.GetAddrOfCXXDestructor(dtor, Dtor_Complete); |
| argument = llvm::ConstantExpr::getBitCast( |
| addr, CGF.getTypes().ConvertType(type)->getPointerTo()); |
| |
| // Otherwise, the standard logic requires a helper function. |
| } else { |
| function = CodeGenFunction(CGM) |
| .generateDestroyHelper(addr, type, CGF.getDestroyer(dtorKind), |
| CGF.needsEHCleanup(dtorKind), &D); |
| argument = llvm::Constant::getNullValue(CGF.Int8PtrTy); |
| } |
| |
| CGM.getCXXABI().registerGlobalDtor(CGF, D, function, argument); |
| } |
| |
| /// Emit code to cause the variable at the given address to be considered as |
| /// constant from this point onwards. |
| static void EmitDeclInvariant(CodeGenFunction &CGF, const VarDecl &D, |
| llvm::Constant *Addr) { |
| // Don't emit the intrinsic if we're not optimizing. |
| if (!CGF.CGM.getCodeGenOpts().OptimizationLevel) |
| return; |
| |
| // Grab the llvm.invariant.start intrinsic. |
| llvm::Intrinsic::ID InvStartID = llvm::Intrinsic::invariant_start; |
| llvm::Constant *InvariantStart = CGF.CGM.getIntrinsic(InvStartID); |
| |
| // Emit a call with the size in bytes of the object. |
| CharUnits WidthChars = CGF.getContext().getTypeSizeInChars(D.getType()); |
| uint64_t Width = WidthChars.getQuantity(); |
| llvm::Value *Args[2] = { llvm::ConstantInt::getSigned(CGF.Int64Ty, Width), |
| llvm::ConstantExpr::getBitCast(Addr, CGF.Int8PtrTy)}; |
| CGF.Builder.CreateCall(InvariantStart, Args); |
| } |
| |
| void CodeGenFunction::EmitCXXGlobalVarDeclInit(const VarDecl &D, |
| llvm::Constant *DeclPtr, |
| bool PerformInit) { |
| |
| const Expr *Init = D.getInit(); |
| QualType T = D.getType(); |
| |
| if (!T->isReferenceType()) { |
| if (PerformInit) |
| EmitDeclInit(*this, D, DeclPtr); |
| if (CGM.isTypeConstant(D.getType(), true)) |
| EmitDeclInvariant(*this, D, DeclPtr); |
| else |
| EmitDeclDestroy(*this, D, DeclPtr); |
| return; |
| } |
| |
| assert(PerformInit && "cannot have constant initializer which needs " |
| "destruction for reference"); |
| unsigned Alignment = getContext().getDeclAlign(&D).getQuantity(); |
| RValue RV = EmitReferenceBindingToExpr(Init); |
| EmitStoreOfScalar(RV.getScalarVal(), DeclPtr, false, Alignment, T); |
| } |
| |
| static llvm::Function * |
| CreateGlobalInitOrDestructFunction(CodeGenModule &CGM, |
| llvm::FunctionType *ty, |
| const Twine &name, |
| bool TLS = false); |
| |
| /// Create a stub function, suitable for being passed to atexit, |
| /// which passes the given address to the given destructor function. |
| static llvm::Constant *createAtExitStub(CodeGenModule &CGM, const VarDecl &VD, |
| llvm::Constant *dtor, |
| llvm::Constant *addr) { |
| // Get the destructor function type, void(*)(void). |
| llvm::FunctionType *ty = llvm::FunctionType::get(CGM.VoidTy, false); |
| SmallString<256> FnName; |
| { |
| llvm::raw_svector_ostream Out(FnName); |
| CGM.getCXXABI().getMangleContext().mangleDynamicAtExitDestructor(&VD, Out); |
| } |
| llvm::Function *fn = |
| CreateGlobalInitOrDestructFunction(CGM, ty, FnName.str()); |
| |
| CodeGenFunction CGF(CGM); |
| |
| CGF.StartFunction(&VD, CGM.getContext().VoidTy, fn, |
| CGM.getTypes().arrangeNullaryFunction(), FunctionArgList(), |
| SourceLocation()); |
| |
| llvm::CallInst *call = CGF.Builder.CreateCall(dtor, addr); |
| |
| // Make sure the call and the callee agree on calling convention. |
| if (llvm::Function *dtorFn = |
| dyn_cast<llvm::Function>(dtor->stripPointerCasts())) |
| call->setCallingConv(dtorFn->getCallingConv()); |
| |
| CGF.FinishFunction(); |
| |
| return fn; |
| } |
| |
| /// Register a global destructor using the C atexit runtime function. |
| void CodeGenFunction::registerGlobalDtorWithAtExit(const VarDecl &VD, |
| llvm::Constant *dtor, |
| llvm::Constant *addr) { |
| // Create a function which calls the destructor. |
| llvm::Constant *dtorStub = createAtExitStub(CGM, VD, dtor, addr); |
| |
| // extern "C" int atexit(void (*f)(void)); |
| llvm::FunctionType *atexitTy = |
| llvm::FunctionType::get(IntTy, dtorStub->getType(), false); |
| |
| llvm::Constant *atexit = |
| CGM.CreateRuntimeFunction(atexitTy, "atexit"); |
| if (llvm::Function *atexitFn = dyn_cast<llvm::Function>(atexit)) |
| atexitFn->setDoesNotThrow(); |
| |
| EmitNounwindRuntimeCall(atexit, dtorStub); |
| } |
| |
| void CodeGenFunction::EmitCXXGuardedInit(const VarDecl &D, |
| llvm::GlobalVariable *DeclPtr, |
| bool PerformInit) { |
| // If we've been asked to forbid guard variables, emit an error now. |
| // This diagnostic is hard-coded for Darwin's use case; we can find |
| // better phrasing if someone else needs it. |
| if (CGM.getCodeGenOpts().ForbidGuardVariables) |
| CGM.Error(D.getLocation(), |
| "this initialization requires a guard variable, which " |
| "the kernel does not support"); |
| |
| CGM.getCXXABI().EmitGuardedInit(*this, D, DeclPtr, PerformInit); |
| } |
| |
| static llvm::Function * |
| CreateGlobalInitOrDestructFunction(CodeGenModule &CGM, |
| llvm::FunctionType *FTy, |
| const Twine &Name, bool TLS) { |
| llvm::Function *Fn = |
| llvm::Function::Create(FTy, llvm::GlobalValue::InternalLinkage, |
| Name, &CGM.getModule()); |
| if (!CGM.getLangOpts().AppleKext && !TLS) { |
| // Set the section if needed. |
| if (const char *Section = |
| CGM.getTarget().getStaticInitSectionSpecifier()) |
| Fn->setSection(Section); |
| } |
| |
| Fn->setCallingConv(CGM.getRuntimeCC()); |
| |
| if (!CGM.getLangOpts().Exceptions) |
| Fn->setDoesNotThrow(); |
| |
| if (CGM.getSanOpts().Address) |
| Fn->addFnAttr(llvm::Attribute::SanitizeAddress); |
| if (CGM.getSanOpts().Thread) |
| Fn->addFnAttr(llvm::Attribute::SanitizeThread); |
| if (CGM.getSanOpts().Memory) |
| Fn->addFnAttr(llvm::Attribute::SanitizeMemory); |
| |
| return Fn; |
| } |
| |
| void |
| CodeGenModule::EmitCXXGlobalVarDeclInitFunc(const VarDecl *D, |
| llvm::GlobalVariable *Addr, |
| bool PerformInit) { |
| llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false); |
| SmallString<256> FnName; |
| { |
| llvm::raw_svector_ostream Out(FnName); |
| getCXXABI().getMangleContext().mangleDynamicInitializer(D, Out); |
| } |
| |
| // Create a variable initialization function. |
| llvm::Function *Fn = |
| CreateGlobalInitOrDestructFunction(*this, FTy, FnName.str()); |
| |
| CodeGenFunction(*this).GenerateCXXGlobalVarDeclInitFunc(Fn, D, Addr, |
| PerformInit); |
| |
| if (D->getTLSKind()) { |
| // FIXME: Should we support init_priority for thread_local? |
| // FIXME: Ideally, initialization of instantiated thread_local static data |
| // members of class templates should not trigger initialization of other |
| // entities in the TU. |
| // FIXME: We only need to register one __cxa_thread_atexit function for the |
| // entire TU. |
| CXXThreadLocalInits.push_back(Fn); |
| } else if (D->hasAttr<InitPriorityAttr>()) { |
| unsigned int order = D->getAttr<InitPriorityAttr>()->getPriority(); |
| OrderGlobalInits Key(order, PrioritizedCXXGlobalInits.size()); |
| PrioritizedCXXGlobalInits.push_back(std::make_pair(Key, Fn)); |
| DelayedCXXInitPosition.erase(D); |
| } else if (D->getTemplateSpecializationKind() != TSK_ExplicitSpecialization && |
| D->getTemplateSpecializationKind() != TSK_Undeclared) { |
| // C++ [basic.start.init]p2: |
| // Definitions of explicitly specialized class template static data |
| // members have ordered initialization. Other class template static data |
| // members (i.e., implicitly or explicitly instantiated specializations) |
| // have unordered initialization. |
| // |
| // As a consequence, we can put them into their own llvm.global_ctors entry. |
| // This should allow GlobalOpt to fire more often, and allow us to implement |
| // the Microsoft C++ ABI, which uses COMDAT elimination to avoid double |
| // initializaiton. |
| AddGlobalCtor(Fn); |
| DelayedCXXInitPosition.erase(D); |
| } else { |
| llvm::DenseMap<const Decl *, unsigned>::iterator I = |
| DelayedCXXInitPosition.find(D); |
| if (I == DelayedCXXInitPosition.end()) { |
| CXXGlobalInits.push_back(Fn); |
| } else { |
| assert(CXXGlobalInits[I->second] == 0); |
| CXXGlobalInits[I->second] = Fn; |
| DelayedCXXInitPosition.erase(I); |
| } |
| } |
| } |
| |
| void CodeGenModule::EmitCXXThreadLocalInitFunc() { |
| llvm::Function *InitFn = 0; |
| if (!CXXThreadLocalInits.empty()) { |
| // Generate a guarded initialization function. |
| llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false); |
| InitFn = CreateGlobalInitOrDestructFunction(*this, FTy, "__tls_init", |
| /*TLS*/ true); |
| llvm::GlobalVariable *Guard = new llvm::GlobalVariable( |
| getModule(), Int8Ty, false, llvm::GlobalVariable::InternalLinkage, |
| llvm::ConstantInt::get(Int8Ty, 0), "__tls_guard"); |
| Guard->setThreadLocal(true); |
| CodeGenFunction(*this) |
| .GenerateCXXGlobalInitFunc(InitFn, CXXThreadLocalInits, Guard); |
| } |
| |
| getCXXABI().EmitThreadLocalInitFuncs(CXXThreadLocals, InitFn); |
| |
| CXXThreadLocalInits.clear(); |
| CXXThreadLocals.clear(); |
| } |
| |
| void |
| CodeGenModule::EmitCXXGlobalInitFunc() { |
| while (!CXXGlobalInits.empty() && !CXXGlobalInits.back()) |
| CXXGlobalInits.pop_back(); |
| |
| if (CXXGlobalInits.empty() && PrioritizedCXXGlobalInits.empty()) |
| return; |
| |
| llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false); |
| |
| |
| // Create our global initialization function. |
| if (!PrioritizedCXXGlobalInits.empty()) { |
| SmallVector<llvm::Constant*, 8> LocalCXXGlobalInits; |
| llvm::array_pod_sort(PrioritizedCXXGlobalInits.begin(), |
| PrioritizedCXXGlobalInits.end()); |
| // Iterate over "chunks" of ctors with same priority and emit each chunk |
| // into separate function. Note - everything is sorted first by priority, |
| // second - by lex order, so we emit ctor functions in proper order. |
| for (SmallVectorImpl<GlobalInitData >::iterator |
| I = PrioritizedCXXGlobalInits.begin(), |
| E = PrioritizedCXXGlobalInits.end(); I != E; ) { |
| SmallVectorImpl<GlobalInitData >::iterator |
| PrioE = std::upper_bound(I + 1, E, *I, GlobalInitPriorityCmp()); |
| |
| LocalCXXGlobalInits.clear(); |
| unsigned Priority = I->first.priority; |
| // Compute the function suffix from priority. Prepend with zeroes to make |
| // sure the function names are also ordered as priorities. |
| std::string PrioritySuffix = llvm::utostr(Priority); |
| // Priority is always <= 65535 (enforced by sema).. |
| PrioritySuffix = std::string(6-PrioritySuffix.size(), '0')+PrioritySuffix; |
| llvm::Function *Fn = |
| CreateGlobalInitOrDestructFunction(*this, FTy, |
| "_GLOBAL__I_" + PrioritySuffix); |
| |
| for (; I < PrioE; ++I) |
| LocalCXXGlobalInits.push_back(I->second); |
| |
| CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn, LocalCXXGlobalInits); |
| AddGlobalCtor(Fn, Priority); |
| } |
| } |
| |
| llvm::Function *Fn = |
| CreateGlobalInitOrDestructFunction(*this, FTy, "_GLOBAL__I_a"); |
| |
| CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn, CXXGlobalInits); |
| AddGlobalCtor(Fn); |
| |
| CXXGlobalInits.clear(); |
| PrioritizedCXXGlobalInits.clear(); |
| } |
| |
| void CodeGenModule::EmitCXXGlobalDtorFunc() { |
| if (CXXGlobalDtors.empty()) |
| return; |
| |
| llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false); |
| |
| // Create our global destructor function. |
| llvm::Function *Fn = |
| CreateGlobalInitOrDestructFunction(*this, FTy, "_GLOBAL__D_a"); |
| |
| CodeGenFunction(*this).GenerateCXXGlobalDtorsFunc(Fn, CXXGlobalDtors); |
| AddGlobalDtor(Fn); |
| } |
| |
| /// Emit the code necessary to initialize the given global variable. |
| void CodeGenFunction::GenerateCXXGlobalVarDeclInitFunc(llvm::Function *Fn, |
| const VarDecl *D, |
| llvm::GlobalVariable *Addr, |
| bool PerformInit) { |
| // Check if we need to emit debug info for variable initializer. |
| if (D->hasAttr<NoDebugAttr>()) |
| DebugInfo = NULL; // disable debug info indefinitely for this function |
| |
| StartFunction(GlobalDecl(D), getContext().VoidTy, Fn, |
| getTypes().arrangeNullaryFunction(), |
| FunctionArgList(), D->getInit()->getExprLoc()); |
| |
| // Use guarded initialization if the global variable is weak. This |
| // occurs for, e.g., instantiated static data members and |
| // definitions explicitly marked weak. |
| if (Addr->getLinkage() == llvm::GlobalValue::WeakODRLinkage || |
| Addr->getLinkage() == llvm::GlobalValue::WeakAnyLinkage) { |
| EmitCXXGuardedInit(*D, Addr, PerformInit); |
| } else { |
| EmitCXXGlobalVarDeclInit(*D, Addr, PerformInit); |
| } |
| |
| FinishFunction(); |
| } |
| |
| void |
| CodeGenFunction::GenerateCXXGlobalInitFunc(llvm::Function *Fn, |
| ArrayRef<llvm::Constant *> Decls, |
| llvm::GlobalVariable *Guard) { |
| StartFunction(GlobalDecl(), getContext().VoidTy, Fn, |
| getTypes().arrangeNullaryFunction(), |
| FunctionArgList(), SourceLocation()); |
| |
| llvm::BasicBlock *ExitBlock = 0; |
| if (Guard) { |
| // If we have a guard variable, check whether we've already performed these |
| // initializations. This happens for TLS initialization functions. |
| llvm::Value *GuardVal = Builder.CreateLoad(Guard); |
| llvm::Value *Uninit = Builder.CreateIsNull(GuardVal, "guard.uninitialized"); |
| // Mark as initialized before initializing anything else. If the |
| // initializers use previously-initialized thread_local vars, that's |
| // probably supposed to be OK, but the standard doesn't say. |
| Builder.CreateStore(llvm::ConstantInt::get(GuardVal->getType(), 1), Guard); |
| llvm::BasicBlock *InitBlock = createBasicBlock("init"); |
| ExitBlock = createBasicBlock("exit"); |
| Builder.CreateCondBr(Uninit, InitBlock, ExitBlock); |
| EmitBlock(InitBlock); |
| } |
| |
| RunCleanupsScope Scope(*this); |
| |
| // When building in Objective-C++ ARC mode, create an autorelease pool |
| // around the global initializers. |
| if (getLangOpts().ObjCAutoRefCount && getLangOpts().CPlusPlus) { |
| llvm::Value *token = EmitObjCAutoreleasePoolPush(); |
| EmitObjCAutoreleasePoolCleanup(token); |
| } |
| |
| for (unsigned i = 0, e = Decls.size(); i != e; ++i) |
| if (Decls[i]) |
| EmitRuntimeCall(Decls[i]); |
| |
| Scope.ForceCleanup(); |
| |
| if (ExitBlock) { |
| Builder.CreateBr(ExitBlock); |
| EmitBlock(ExitBlock); |
| } |
| |
| FinishFunction(); |
| } |
| |
| void CodeGenFunction::GenerateCXXGlobalDtorsFunc(llvm::Function *Fn, |
| const std::vector<std::pair<llvm::WeakVH, llvm::Constant*> > |
| &DtorsAndObjects) { |
| StartFunction(GlobalDecl(), getContext().VoidTy, Fn, |
| getTypes().arrangeNullaryFunction(), |
| FunctionArgList(), SourceLocation()); |
| |
| // Emit the dtors, in reverse order from construction. |
| for (unsigned i = 0, e = DtorsAndObjects.size(); i != e; ++i) { |
| llvm::Value *Callee = DtorsAndObjects[e - i - 1].first; |
| llvm::CallInst *CI = Builder.CreateCall(Callee, |
| DtorsAndObjects[e - i - 1].second); |
| // Make sure the call and the callee agree on calling convention. |
| if (llvm::Function *F = dyn_cast<llvm::Function>(Callee)) |
| CI->setCallingConv(F->getCallingConv()); |
| } |
| |
| FinishFunction(); |
| } |
| |
| /// generateDestroyHelper - Generates a helper function which, when |
| /// invoked, destroys the given object. |
| llvm::Function *CodeGenFunction::generateDestroyHelper( |
| llvm::Constant *addr, QualType type, Destroyer *destroyer, |
| bool useEHCleanupForArray, const VarDecl *VD) { |
| FunctionArgList args; |
| ImplicitParamDecl dst(0, SourceLocation(), 0, getContext().VoidPtrTy); |
| args.push_back(&dst); |
| |
| const CGFunctionInfo &FI = |
| CGM.getTypes().arrangeFunctionDeclaration(getContext().VoidTy, args, |
| FunctionType::ExtInfo(), |
| /*variadic*/ false); |
| llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(FI); |
| llvm::Function *fn = |
| CreateGlobalInitOrDestructFunction(CGM, FTy, "__cxx_global_array_dtor"); |
| |
| StartFunction(VD, getContext().VoidTy, fn, FI, args, SourceLocation()); |
| |
| emitDestroy(addr, type, destroyer, useEHCleanupForArray); |
| |
| FinishFunction(); |
| |
| return fn; |
| } |