CGDeclCXX.cpp revision 5f9e272e632e951b1efe824cd16acb4d96077930
1//===--- CGDeclCXX.cpp - Emit LLVM Code for C++ declarations --------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This contains code dealing with code generation of C++ declarations 11// 12//===----------------------------------------------------------------------===// 13 14#include "CodeGenFunction.h" 15#include "CGObjCRuntime.h" 16#include "CGCXXABI.h" 17#include "clang/Frontend/CodeGenOptions.h" 18#include "llvm/Intrinsics.h" 19 20using namespace clang; 21using namespace CodeGen; 22 23static void EmitDeclInit(CodeGenFunction &CGF, const VarDecl &D, 24 llvm::Constant *DeclPtr) { 25 assert(D.hasGlobalStorage() && "VarDecl must have global storage!"); 26 assert(!D.getType()->isReferenceType() && 27 "Should not call EmitDeclInit on a reference!"); 28 29 ASTContext &Context = CGF.getContext(); 30 31 unsigned alignment = Context.getDeclAlign(&D).getQuantity(); 32 QualType type = D.getType(); 33 LValue lv = CGF.MakeAddrLValue(DeclPtr, type, alignment); 34 35 const Expr *Init = D.getInit(); 36 if (!CGF.hasAggregateLLVMType(type)) { 37 CodeGenModule &CGM = CGF.CGM; 38 if (lv.isObjCStrong()) 39 CGM.getObjCRuntime().EmitObjCGlobalAssign(CGF, CGF.EmitScalarExpr(Init), 40 DeclPtr, D.isThreadSpecified()); 41 else if (lv.isObjCWeak()) 42 CGM.getObjCRuntime().EmitObjCWeakAssign(CGF, CGF.EmitScalarExpr(Init), 43 DeclPtr); 44 else 45 CGF.EmitScalarInit(Init, &D, lv, false); 46 } else if (type->isAnyComplexType()) { 47 CGF.EmitComplexExprIntoAddr(Init, DeclPtr, lv.isVolatile()); 48 } else { 49 CGF.EmitAggExpr(Init, AggValueSlot::forLValue(lv, true)); 50 } 51} 52 53/// Emit code to cause the destruction of the given variable with 54/// static storage duration. 55static void EmitDeclDestroy(CodeGenFunction &CGF, const VarDecl &D, 56 llvm::Constant *addr) { 57 CodeGenModule &CGM = CGF.CGM; 58 59 // FIXME: __attribute__((cleanup)) ? 60 61 QualType type = D.getType(); 62 QualType::DestructionKind dtorKind = type.isDestructedType(); 63 64 switch (dtorKind) { 65 case QualType::DK_none: 66 return; 67 68 case QualType::DK_cxx_destructor: 69 break; 70 71 case QualType::DK_objc_strong_lifetime: 72 case QualType::DK_objc_weak_lifetime: 73 // We don't care about releasing objects during process teardown. 74 return; 75 } 76 77 llvm::Constant *function; 78 llvm::Constant *argument; 79 80 // Special-case non-array C++ destructors, where there's a function 81 // with the right signature that we can just call. 82 const CXXRecordDecl *record = 0; 83 if (dtorKind == QualType::DK_cxx_destructor && 84 (record = type->getAsCXXRecordDecl())) { 85 assert(!record->hasTrivialDestructor()); 86 CXXDestructorDecl *dtor = record->getDestructor(); 87 88 function = CGM.GetAddrOfCXXDestructor(dtor, Dtor_Complete); 89 argument = addr; 90 91 // Otherwise, the standard logic requires a helper function. 92 } else { 93 function = CodeGenFunction(CGM).generateDestroyHelper(addr, type, 94 CGF.getDestroyer(dtorKind), 95 CGF.needsEHCleanup(dtorKind)); 96 argument = llvm::Constant::getNullValue(CGF.Int8PtrTy); 97 } 98 99 CGF.EmitCXXGlobalDtorRegistration(function, argument); 100} 101 102void CodeGenFunction::EmitCXXGlobalVarDeclInit(const VarDecl &D, 103 llvm::Constant *DeclPtr) { 104 105 const Expr *Init = D.getInit(); 106 QualType T = D.getType(); 107 108 if (!T->isReferenceType()) { 109 EmitDeclInit(*this, D, DeclPtr); 110 EmitDeclDestroy(*this, D, DeclPtr); 111 return; 112 } 113 114 unsigned Alignment = getContext().getDeclAlign(&D).getQuantity(); 115 RValue RV = EmitReferenceBindingToExpr(Init, &D); 116 EmitStoreOfScalar(RV.getScalarVal(), DeclPtr, false, Alignment, T); 117} 118 119void 120CodeGenFunction::EmitCXXGlobalDtorRegistration(llvm::Constant *DtorFn, 121 llvm::Constant *DeclPtr) { 122 // Generate a global destructor entry if not using __cxa_atexit. 123 if (!CGM.getCodeGenOpts().CXAAtExit) { 124 CGM.AddCXXDtorEntry(DtorFn, DeclPtr); 125 return; 126 } 127 128 // Get the destructor function type 129 llvm::Type *ArgTys[] = { Int8PtrTy }; 130 llvm::Type *DtorFnTy = 131 llvm::FunctionType::get(llvm::Type::getVoidTy(getLLVMContext()), 132 ArgTys, false); 133 DtorFnTy = llvm::PointerType::getUnqual(DtorFnTy); 134 135 llvm::Type *Params[] = { DtorFnTy, Int8PtrTy, Int8PtrTy }; 136 137 // Get the __cxa_atexit function type 138 // extern "C" int __cxa_atexit ( void (*f)(void *), void *p, void *d ); 139 llvm::FunctionType *AtExitFnTy = 140 llvm::FunctionType::get(ConvertType(getContext().IntTy), Params, false); 141 142 llvm::Constant *AtExitFn = CGM.CreateRuntimeFunction(AtExitFnTy, 143 "__cxa_atexit"); 144 if (llvm::Function *Fn = dyn_cast<llvm::Function>(AtExitFn)) 145 Fn->setDoesNotThrow(); 146 147 llvm::Constant *Handle = CGM.CreateRuntimeVariable(Int8PtrTy, 148 "__dso_handle"); 149 llvm::Value *Args[3] = { llvm::ConstantExpr::getBitCast(DtorFn, DtorFnTy), 150 llvm::ConstantExpr::getBitCast(DeclPtr, Int8PtrTy), 151 llvm::ConstantExpr::getBitCast(Handle, Int8PtrTy) }; 152 Builder.CreateCall(AtExitFn, Args); 153} 154 155void CodeGenFunction::EmitCXXGuardedInit(const VarDecl &D, 156 llvm::GlobalVariable *DeclPtr) { 157 // If we've been asked to forbid guard variables, emit an error now. 158 // This diagnostic is hard-coded for Darwin's use case; we can find 159 // better phrasing if someone else needs it. 160 if (CGM.getCodeGenOpts().ForbidGuardVariables) 161 CGM.Error(D.getLocation(), 162 "this initialization requires a guard variable, which " 163 "the kernel does not support"); 164 165 CGM.getCXXABI().EmitGuardedInit(*this, D, DeclPtr); 166} 167 168static llvm::Function * 169CreateGlobalInitOrDestructFunction(CodeGenModule &CGM, 170 llvm::FunctionType *FTy, 171 StringRef Name) { 172 llvm::Function *Fn = 173 llvm::Function::Create(FTy, llvm::GlobalValue::InternalLinkage, 174 Name, &CGM.getModule()); 175 if (!CGM.getContext().getLangOptions().AppleKext) { 176 // Set the section if needed. 177 if (const char *Section = 178 CGM.getContext().Target.getStaticInitSectionSpecifier()) 179 Fn->setSection(Section); 180 } 181 182 if (!CGM.getLangOptions().Exceptions) 183 Fn->setDoesNotThrow(); 184 185 return Fn; 186} 187 188void 189CodeGenModule::EmitCXXGlobalVarDeclInitFunc(const VarDecl *D, 190 llvm::GlobalVariable *Addr) { 191 llvm::FunctionType *FTy 192 = llvm::FunctionType::get(llvm::Type::getVoidTy(VMContext), 193 false); 194 195 // Create a variable initialization function. 196 llvm::Function *Fn = 197 CreateGlobalInitOrDestructFunction(*this, FTy, "__cxx_global_var_init"); 198 199 CodeGenFunction(*this).GenerateCXXGlobalVarDeclInitFunc(Fn, D, Addr); 200 201 if (D->hasAttr<InitPriorityAttr>()) { 202 unsigned int order = D->getAttr<InitPriorityAttr>()->getPriority(); 203 OrderGlobalInits Key(order, PrioritizedCXXGlobalInits.size()); 204 PrioritizedCXXGlobalInits.push_back(std::make_pair(Key, Fn)); 205 DelayedCXXInitPosition.erase(D); 206 } 207 else { 208 llvm::DenseMap<const Decl *, unsigned>::iterator I = 209 DelayedCXXInitPosition.find(D); 210 if (I == DelayedCXXInitPosition.end()) { 211 CXXGlobalInits.push_back(Fn); 212 } else { 213 assert(CXXGlobalInits[I->second] == 0); 214 CXXGlobalInits[I->second] = Fn; 215 DelayedCXXInitPosition.erase(I); 216 } 217 } 218} 219 220void 221CodeGenModule::EmitCXXGlobalInitFunc() { 222 while (!CXXGlobalInits.empty() && !CXXGlobalInits.back()) 223 CXXGlobalInits.pop_back(); 224 225 if (CXXGlobalInits.empty() && PrioritizedCXXGlobalInits.empty()) 226 return; 227 228 llvm::FunctionType *FTy 229 = llvm::FunctionType::get(llvm::Type::getVoidTy(VMContext), 230 false); 231 232 // Create our global initialization function. 233 llvm::Function *Fn = 234 CreateGlobalInitOrDestructFunction(*this, FTy, "_GLOBAL__I_a"); 235 236 if (!PrioritizedCXXGlobalInits.empty()) { 237 SmallVector<llvm::Constant*, 8> LocalCXXGlobalInits; 238 llvm::array_pod_sort(PrioritizedCXXGlobalInits.begin(), 239 PrioritizedCXXGlobalInits.end()); 240 for (unsigned i = 0; i < PrioritizedCXXGlobalInits.size(); i++) { 241 llvm::Function *Fn = PrioritizedCXXGlobalInits[i].second; 242 LocalCXXGlobalInits.push_back(Fn); 243 } 244 LocalCXXGlobalInits.append(CXXGlobalInits.begin(), CXXGlobalInits.end()); 245 CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn, 246 &LocalCXXGlobalInits[0], 247 LocalCXXGlobalInits.size()); 248 } 249 else 250 CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn, 251 &CXXGlobalInits[0], 252 CXXGlobalInits.size()); 253 AddGlobalCtor(Fn); 254 CXXGlobalInits.clear(); 255 PrioritizedCXXGlobalInits.clear(); 256} 257 258void CodeGenModule::EmitCXXGlobalDtorFunc() { 259 if (CXXGlobalDtors.empty()) 260 return; 261 262 llvm::FunctionType *FTy 263 = llvm::FunctionType::get(llvm::Type::getVoidTy(VMContext), 264 false); 265 266 // Create our global destructor function. 267 llvm::Function *Fn = 268 CreateGlobalInitOrDestructFunction(*this, FTy, "_GLOBAL__D_a"); 269 270 CodeGenFunction(*this).GenerateCXXGlobalDtorFunc(Fn, CXXGlobalDtors); 271 AddGlobalDtor(Fn); 272} 273 274/// Emit the code necessary to initialize the given global variable. 275void CodeGenFunction::GenerateCXXGlobalVarDeclInitFunc(llvm::Function *Fn, 276 const VarDecl *D, 277 llvm::GlobalVariable *Addr) { 278 StartFunction(GlobalDecl(), getContext().VoidTy, Fn, 279 getTypes().getNullaryFunctionInfo(), 280 FunctionArgList(), SourceLocation()); 281 282 // Use guarded initialization if the global variable is weak. This 283 // occurs for, e.g., instantiated static data members and 284 // definitions explicitly marked weak. 285 if (Addr->getLinkage() == llvm::GlobalValue::WeakODRLinkage || 286 Addr->getLinkage() == llvm::GlobalValue::WeakAnyLinkage) { 287 EmitCXXGuardedInit(*D, Addr); 288 } else { 289 EmitCXXGlobalVarDeclInit(*D, Addr); 290 } 291 292 FinishFunction(); 293} 294 295void CodeGenFunction::GenerateCXXGlobalInitFunc(llvm::Function *Fn, 296 llvm::Constant **Decls, 297 unsigned NumDecls) { 298 StartFunction(GlobalDecl(), getContext().VoidTy, Fn, 299 getTypes().getNullaryFunctionInfo(), 300 FunctionArgList(), SourceLocation()); 301 302 RunCleanupsScope Scope(*this); 303 304 // When building in Objective-C++ ARC mode, create an autorelease pool 305 // around the global initializers. 306 if (getLangOptions().ObjCAutoRefCount && getLangOptions().CPlusPlus) { 307 llvm::Value *token = EmitObjCAutoreleasePoolPush(); 308 EmitObjCAutoreleasePoolCleanup(token); 309 } 310 311 for (unsigned i = 0; i != NumDecls; ++i) 312 if (Decls[i]) 313 Builder.CreateCall(Decls[i]); 314 315 Scope.ForceCleanup(); 316 317 FinishFunction(); 318} 319 320void CodeGenFunction::GenerateCXXGlobalDtorFunc(llvm::Function *Fn, 321 const std::vector<std::pair<llvm::WeakVH, llvm::Constant*> > 322 &DtorsAndObjects) { 323 StartFunction(GlobalDecl(), getContext().VoidTy, Fn, 324 getTypes().getNullaryFunctionInfo(), 325 FunctionArgList(), SourceLocation()); 326 327 // Emit the dtors, in reverse order from construction. 328 for (unsigned i = 0, e = DtorsAndObjects.size(); i != e; ++i) { 329 llvm::Value *Callee = DtorsAndObjects[e - i - 1].first; 330 llvm::CallInst *CI = Builder.CreateCall(Callee, 331 DtorsAndObjects[e - i - 1].second); 332 // Make sure the call and the callee agree on calling convention. 333 if (llvm::Function *F = dyn_cast<llvm::Function>(Callee)) 334 CI->setCallingConv(F->getCallingConv()); 335 } 336 337 FinishFunction(); 338} 339 340/// generateDestroyHelper - Generates a helper function which, when 341/// invoked, destroys the given object. 342llvm::Function * 343CodeGenFunction::generateDestroyHelper(llvm::Constant *addr, 344 QualType type, 345 Destroyer &destroyer, 346 bool useEHCleanupForArray) { 347 FunctionArgList args; 348 ImplicitParamDecl dst(0, SourceLocation(), 0, getContext().VoidPtrTy); 349 args.push_back(&dst); 350 351 const CGFunctionInfo &FI = 352 CGM.getTypes().getFunctionInfo(getContext().VoidTy, args, 353 FunctionType::ExtInfo()); 354 llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(FI, false); 355 llvm::Function *fn = 356 CreateGlobalInitOrDestructFunction(CGM, FTy, "__cxx_global_array_dtor"); 357 358 StartFunction(GlobalDecl(), getContext().VoidTy, fn, FI, args, 359 SourceLocation()); 360 361 emitDestroy(addr, type, destroyer, useEHCleanupForArray); 362 363 FinishFunction(); 364 365 return fn; 366} 367 368