1 //===--- CGDecl.cpp - Emit LLVM Code for 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 to emit Decl nodes as LLVM code. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "CodeGenFunction.h" 15 #include "CGBlocks.h" 16 #include "CGCleanup.h" 17 #include "CGDebugInfo.h" 18 #include "CGOpenCLRuntime.h" 19 #include "CGOpenMPRuntime.h" 20 #include "CodeGenModule.h" 21 #include "clang/AST/ASTContext.h" 22 #include "clang/AST/CharUnits.h" 23 #include "clang/AST/Decl.h" 24 #include "clang/AST/DeclObjC.h" 25 #include "clang/AST/DeclOpenMP.h" 26 #include "clang/Basic/SourceManager.h" 27 #include "clang/Basic/TargetInfo.h" 28 #include "clang/CodeGen/CGFunctionInfo.h" 29 #include "clang/Frontend/CodeGenOptions.h" 30 #include "llvm/IR/DataLayout.h" 31 #include "llvm/IR/GlobalVariable.h" 32 #include "llvm/IR/Intrinsics.h" 33 #include "llvm/IR/Type.h" 34 35 using namespace clang; 36 using namespace CodeGen; 37 38 void CodeGenFunction::EmitDecl(const Decl &D) { 39 switch (D.getKind()) { 40 case Decl::BuiltinTemplate: 41 case Decl::TranslationUnit: 42 case Decl::ExternCContext: 43 case Decl::Namespace: 44 case Decl::UnresolvedUsingTypename: 45 case Decl::ClassTemplateSpecialization: 46 case Decl::ClassTemplatePartialSpecialization: 47 case Decl::VarTemplateSpecialization: 48 case Decl::VarTemplatePartialSpecialization: 49 case Decl::TemplateTypeParm: 50 case Decl::UnresolvedUsingValue: 51 case Decl::NonTypeTemplateParm: 52 case Decl::CXXMethod: 53 case Decl::CXXConstructor: 54 case Decl::CXXDestructor: 55 case Decl::CXXConversion: 56 case Decl::Field: 57 case Decl::MSProperty: 58 case Decl::IndirectField: 59 case Decl::ObjCIvar: 60 case Decl::ObjCAtDefsField: 61 case Decl::ParmVar: 62 case Decl::ImplicitParam: 63 case Decl::ClassTemplate: 64 case Decl::VarTemplate: 65 case Decl::FunctionTemplate: 66 case Decl::TypeAliasTemplate: 67 case Decl::TemplateTemplateParm: 68 case Decl::ObjCMethod: 69 case Decl::ObjCCategory: 70 case Decl::ObjCProtocol: 71 case Decl::ObjCInterface: 72 case Decl::ObjCCategoryImpl: 73 case Decl::ObjCImplementation: 74 case Decl::ObjCProperty: 75 case Decl::ObjCCompatibleAlias: 76 case Decl::PragmaComment: 77 case Decl::PragmaDetectMismatch: 78 case Decl::AccessSpec: 79 case Decl::LinkageSpec: 80 case Decl::ObjCPropertyImpl: 81 case Decl::FileScopeAsm: 82 case Decl::Friend: 83 case Decl::FriendTemplate: 84 case Decl::Block: 85 case Decl::Captured: 86 case Decl::ClassScopeFunctionSpecialization: 87 case Decl::UsingShadow: 88 case Decl::ObjCTypeParam: 89 llvm_unreachable("Declaration should not be in declstmts!"); 90 case Decl::Function: // void X(); 91 case Decl::Record: // struct/union/class X; 92 case Decl::Enum: // enum X; 93 case Decl::EnumConstant: // enum ? { X = ? } 94 case Decl::CXXRecord: // struct/union/class X; [C++] 95 case Decl::StaticAssert: // static_assert(X, ""); [C++0x] 96 case Decl::Label: // __label__ x; 97 case Decl::Import: 98 case Decl::OMPThreadPrivate: 99 case Decl::OMPCapturedExpr: 100 case Decl::Empty: 101 // None of these decls require codegen support. 102 return; 103 104 case Decl::NamespaceAlias: 105 if (CGDebugInfo *DI = getDebugInfo()) 106 DI->EmitNamespaceAlias(cast<NamespaceAliasDecl>(D)); 107 return; 108 case Decl::Using: // using X; [C++] 109 if (CGDebugInfo *DI = getDebugInfo()) 110 DI->EmitUsingDecl(cast<UsingDecl>(D)); 111 return; 112 case Decl::UsingDirective: // using namespace X; [C++] 113 if (CGDebugInfo *DI = getDebugInfo()) 114 DI->EmitUsingDirective(cast<UsingDirectiveDecl>(D)); 115 return; 116 case Decl::Var: { 117 const VarDecl &VD = cast<VarDecl>(D); 118 assert(VD.isLocalVarDecl() && 119 "Should not see file-scope variables inside a function!"); 120 return EmitVarDecl(VD); 121 } 122 123 case Decl::OMPDeclareReduction: 124 return CGM.EmitOMPDeclareReduction(cast<OMPDeclareReductionDecl>(&D), this); 125 126 case Decl::Typedef: // typedef int X; 127 case Decl::TypeAlias: { // using X = int; [C++0x] 128 const TypedefNameDecl &TD = cast<TypedefNameDecl>(D); 129 QualType Ty = TD.getUnderlyingType(); 130 131 if (Ty->isVariablyModifiedType()) 132 EmitVariablyModifiedType(Ty); 133 } 134 } 135 } 136 137 /// EmitVarDecl - This method handles emission of any variable declaration 138 /// inside a function, including static vars etc. 139 void CodeGenFunction::EmitVarDecl(const VarDecl &D) { 140 if (D.isStaticLocal()) { 141 llvm::GlobalValue::LinkageTypes Linkage = 142 CGM.getLLVMLinkageVarDefinition(&D, /*isConstant=*/false); 143 144 // FIXME: We need to force the emission/use of a guard variable for 145 // some variables even if we can constant-evaluate them because 146 // we can't guarantee every translation unit will constant-evaluate them. 147 148 return EmitStaticVarDecl(D, Linkage); 149 } 150 151 if (D.hasExternalStorage()) 152 // Don't emit it now, allow it to be emitted lazily on its first use. 153 return; 154 155 if (D.getType().getAddressSpace() == LangAS::opencl_local) 156 return CGM.getOpenCLRuntime().EmitWorkGroupLocalVarDecl(*this, D); 157 158 assert(D.hasLocalStorage()); 159 return EmitAutoVarDecl(D); 160 } 161 162 static std::string getStaticDeclName(CodeGenModule &CGM, const VarDecl &D) { 163 if (CGM.getLangOpts().CPlusPlus) 164 return CGM.getMangledName(&D).str(); 165 166 // If this isn't C++, we don't need a mangled name, just a pretty one. 167 assert(!D.isExternallyVisible() && "name shouldn't matter"); 168 std::string ContextName; 169 const DeclContext *DC = D.getDeclContext(); 170 if (auto *CD = dyn_cast<CapturedDecl>(DC)) 171 DC = cast<DeclContext>(CD->getNonClosureContext()); 172 if (const auto *FD = dyn_cast<FunctionDecl>(DC)) 173 ContextName = CGM.getMangledName(FD); 174 else if (const auto *BD = dyn_cast<BlockDecl>(DC)) 175 ContextName = CGM.getBlockMangledName(GlobalDecl(), BD); 176 else if (const auto *OMD = dyn_cast<ObjCMethodDecl>(DC)) 177 ContextName = OMD->getSelector().getAsString(); 178 else 179 llvm_unreachable("Unknown context for static var decl"); 180 181 ContextName += "." + D.getNameAsString(); 182 return ContextName; 183 } 184 185 llvm::Constant *CodeGenModule::getOrCreateStaticVarDecl( 186 const VarDecl &D, llvm::GlobalValue::LinkageTypes Linkage) { 187 // In general, we don't always emit static var decls once before we reference 188 // them. It is possible to reference them before emitting the function that 189 // contains them, and it is possible to emit the containing function multiple 190 // times. 191 if (llvm::Constant *ExistingGV = StaticLocalDeclMap[&D]) 192 return ExistingGV; 193 194 QualType Ty = D.getType(); 195 assert(Ty->isConstantSizeType() && "VLAs can't be static"); 196 197 // Use the label if the variable is renamed with the asm-label extension. 198 std::string Name; 199 if (D.hasAttr<AsmLabelAttr>()) 200 Name = getMangledName(&D); 201 else 202 Name = getStaticDeclName(*this, D); 203 204 llvm::Type *LTy = getTypes().ConvertTypeForMem(Ty); 205 unsigned AddrSpace = 206 GetGlobalVarAddressSpace(&D, getContext().getTargetAddressSpace(Ty)); 207 208 // Local address space cannot have an initializer. 209 llvm::Constant *Init = nullptr; 210 if (Ty.getAddressSpace() != LangAS::opencl_local) 211 Init = EmitNullConstant(Ty); 212 else 213 Init = llvm::UndefValue::get(LTy); 214 215 llvm::GlobalVariable *GV = 216 new llvm::GlobalVariable(getModule(), LTy, 217 Ty.isConstant(getContext()), Linkage, 218 Init, Name, nullptr, 219 llvm::GlobalVariable::NotThreadLocal, 220 AddrSpace); 221 GV->setAlignment(getContext().getDeclAlign(&D).getQuantity()); 222 setGlobalVisibility(GV, &D); 223 224 if (supportsCOMDAT() && GV->isWeakForLinker()) 225 GV->setComdat(TheModule.getOrInsertComdat(GV->getName())); 226 227 if (D.getTLSKind()) 228 setTLSMode(GV, D); 229 230 if (D.isExternallyVisible()) { 231 if (D.hasAttr<DLLImportAttr>()) 232 GV->setDLLStorageClass(llvm::GlobalVariable::DLLImportStorageClass); 233 else if (D.hasAttr<DLLExportAttr>()) 234 GV->setDLLStorageClass(llvm::GlobalVariable::DLLExportStorageClass); 235 } 236 237 // Make sure the result is of the correct type. 238 unsigned ExpectedAddrSpace = getContext().getTargetAddressSpace(Ty); 239 llvm::Constant *Addr = GV; 240 if (AddrSpace != ExpectedAddrSpace) { 241 llvm::PointerType *PTy = llvm::PointerType::get(LTy, ExpectedAddrSpace); 242 Addr = llvm::ConstantExpr::getAddrSpaceCast(GV, PTy); 243 } 244 245 setStaticLocalDeclAddress(&D, Addr); 246 247 // Ensure that the static local gets initialized by making sure the parent 248 // function gets emitted eventually. 249 const Decl *DC = cast<Decl>(D.getDeclContext()); 250 251 // We can't name blocks or captured statements directly, so try to emit their 252 // parents. 253 if (isa<BlockDecl>(DC) || isa<CapturedDecl>(DC)) { 254 DC = DC->getNonClosureContext(); 255 // FIXME: Ensure that global blocks get emitted. 256 if (!DC) 257 return Addr; 258 } 259 260 GlobalDecl GD; 261 if (const auto *CD = dyn_cast<CXXConstructorDecl>(DC)) 262 GD = GlobalDecl(CD, Ctor_Base); 263 else if (const auto *DD = dyn_cast<CXXDestructorDecl>(DC)) 264 GD = GlobalDecl(DD, Dtor_Base); 265 else if (const auto *FD = dyn_cast<FunctionDecl>(DC)) 266 GD = GlobalDecl(FD); 267 else { 268 // Don't do anything for Obj-C method decls or global closures. We should 269 // never defer them. 270 assert(isa<ObjCMethodDecl>(DC) && "unexpected parent code decl"); 271 } 272 if (GD.getDecl()) 273 (void)GetAddrOfGlobal(GD); 274 275 return Addr; 276 } 277 278 /// hasNontrivialDestruction - Determine whether a type's destruction is 279 /// non-trivial. If so, and the variable uses static initialization, we must 280 /// register its destructor to run on exit. 281 static bool hasNontrivialDestruction(QualType T) { 282 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl(); 283 return RD && !RD->hasTrivialDestructor(); 284 } 285 286 /// AddInitializerToStaticVarDecl - Add the initializer for 'D' to the 287 /// global variable that has already been created for it. If the initializer 288 /// has a different type than GV does, this may free GV and return a different 289 /// one. Otherwise it just returns GV. 290 llvm::GlobalVariable * 291 CodeGenFunction::AddInitializerToStaticVarDecl(const VarDecl &D, 292 llvm::GlobalVariable *GV) { 293 llvm::Constant *Init = CGM.EmitConstantInit(D, this); 294 295 // If constant emission failed, then this should be a C++ static 296 // initializer. 297 if (!Init) { 298 if (!getLangOpts().CPlusPlus) 299 CGM.ErrorUnsupported(D.getInit(), "constant l-value expression"); 300 else if (Builder.GetInsertBlock()) { 301 // Since we have a static initializer, this global variable can't 302 // be constant. 303 GV->setConstant(false); 304 305 EmitCXXGuardedInit(D, GV, /*PerformInit*/true); 306 } 307 return GV; 308 } 309 310 // The initializer may differ in type from the global. Rewrite 311 // the global to match the initializer. (We have to do this 312 // because some types, like unions, can't be completely represented 313 // in the LLVM type system.) 314 if (GV->getType()->getElementType() != Init->getType()) { 315 llvm::GlobalVariable *OldGV = GV; 316 317 GV = new llvm::GlobalVariable(CGM.getModule(), Init->getType(), 318 OldGV->isConstant(), 319 OldGV->getLinkage(), Init, "", 320 /*InsertBefore*/ OldGV, 321 OldGV->getThreadLocalMode(), 322 CGM.getContext().getTargetAddressSpace(D.getType())); 323 GV->setVisibility(OldGV->getVisibility()); 324 GV->setComdat(OldGV->getComdat()); 325 326 // Steal the name of the old global 327 GV->takeName(OldGV); 328 329 // Replace all uses of the old global with the new global 330 llvm::Constant *NewPtrForOldDecl = 331 llvm::ConstantExpr::getBitCast(GV, OldGV->getType()); 332 OldGV->replaceAllUsesWith(NewPtrForOldDecl); 333 334 // Erase the old global, since it is no longer used. 335 OldGV->eraseFromParent(); 336 } 337 338 GV->setConstant(CGM.isTypeConstant(D.getType(), true)); 339 GV->setInitializer(Init); 340 341 if (hasNontrivialDestruction(D.getType())) { 342 // We have a constant initializer, but a nontrivial destructor. We still 343 // need to perform a guarded "initialization" in order to register the 344 // destructor. 345 EmitCXXGuardedInit(D, GV, /*PerformInit*/false); 346 } 347 348 return GV; 349 } 350 351 void CodeGenFunction::EmitStaticVarDecl(const VarDecl &D, 352 llvm::GlobalValue::LinkageTypes Linkage) { 353 // Check to see if we already have a global variable for this 354 // declaration. This can happen when double-emitting function 355 // bodies, e.g. with complete and base constructors. 356 llvm::Constant *addr = CGM.getOrCreateStaticVarDecl(D, Linkage); 357 CharUnits alignment = getContext().getDeclAlign(&D); 358 359 // Store into LocalDeclMap before generating initializer to handle 360 // circular references. 361 setAddrOfLocalVar(&D, Address(addr, alignment)); 362 363 // We can't have a VLA here, but we can have a pointer to a VLA, 364 // even though that doesn't really make any sense. 365 // Make sure to evaluate VLA bounds now so that we have them for later. 366 if (D.getType()->isVariablyModifiedType()) 367 EmitVariablyModifiedType(D.getType()); 368 369 // Save the type in case adding the initializer forces a type change. 370 llvm::Type *expectedType = addr->getType(); 371 372 llvm::GlobalVariable *var = 373 cast<llvm::GlobalVariable>(addr->stripPointerCasts()); 374 375 // CUDA's local and local static __shared__ variables should not 376 // have any non-empty initializers. This is ensured by Sema. 377 // Whatever initializer such variable may have when it gets here is 378 // a no-op and should not be emitted. 379 bool isCudaSharedVar = getLangOpts().CUDA && getLangOpts().CUDAIsDevice && 380 D.hasAttr<CUDASharedAttr>(); 381 // If this value has an initializer, emit it. 382 if (D.getInit() && !isCudaSharedVar) 383 var = AddInitializerToStaticVarDecl(D, var); 384 385 var->setAlignment(alignment.getQuantity()); 386 387 if (D.hasAttr<AnnotateAttr>()) 388 CGM.AddGlobalAnnotations(&D, var); 389 390 if (const SectionAttr *SA = D.getAttr<SectionAttr>()) 391 var->setSection(SA->getName()); 392 393 if (D.hasAttr<UsedAttr>()) 394 CGM.addUsedGlobal(var); 395 396 // We may have to cast the constant because of the initializer 397 // mismatch above. 398 // 399 // FIXME: It is really dangerous to store this in the map; if anyone 400 // RAUW's the GV uses of this constant will be invalid. 401 llvm::Constant *castedAddr = 402 llvm::ConstantExpr::getPointerBitCastOrAddrSpaceCast(var, expectedType); 403 if (var != castedAddr) 404 LocalDeclMap.find(&D)->second = Address(castedAddr, alignment); 405 CGM.setStaticLocalDeclAddress(&D, castedAddr); 406 407 CGM.getSanitizerMetadata()->reportGlobalToASan(var, D); 408 409 // Emit global variable debug descriptor for static vars. 410 CGDebugInfo *DI = getDebugInfo(); 411 if (DI && 412 CGM.getCodeGenOpts().getDebugInfo() >= codegenoptions::LimitedDebugInfo) { 413 DI->setLocation(D.getLocation()); 414 DI->EmitGlobalVariable(var, &D); 415 } 416 } 417 418 namespace { 419 struct DestroyObject final : EHScopeStack::Cleanup { 420 DestroyObject(Address addr, QualType type, 421 CodeGenFunction::Destroyer *destroyer, 422 bool useEHCleanupForArray) 423 : addr(addr), type(type), destroyer(destroyer), 424 useEHCleanupForArray(useEHCleanupForArray) {} 425 426 Address addr; 427 QualType type; 428 CodeGenFunction::Destroyer *destroyer; 429 bool useEHCleanupForArray; 430 431 void Emit(CodeGenFunction &CGF, Flags flags) override { 432 // Don't use an EH cleanup recursively from an EH cleanup. 433 bool useEHCleanupForArray = 434 flags.isForNormalCleanup() && this->useEHCleanupForArray; 435 436 CGF.emitDestroy(addr, type, destroyer, useEHCleanupForArray); 437 } 438 }; 439 440 struct DestroyNRVOVariable final : EHScopeStack::Cleanup { 441 DestroyNRVOVariable(Address addr, 442 const CXXDestructorDecl *Dtor, 443 llvm::Value *NRVOFlag) 444 : Dtor(Dtor), NRVOFlag(NRVOFlag), Loc(addr) {} 445 446 const CXXDestructorDecl *Dtor; 447 llvm::Value *NRVOFlag; 448 Address Loc; 449 450 void Emit(CodeGenFunction &CGF, Flags flags) override { 451 // Along the exceptions path we always execute the dtor. 452 bool NRVO = flags.isForNormalCleanup() && NRVOFlag; 453 454 llvm::BasicBlock *SkipDtorBB = nullptr; 455 if (NRVO) { 456 // If we exited via NRVO, we skip the destructor call. 457 llvm::BasicBlock *RunDtorBB = CGF.createBasicBlock("nrvo.unused"); 458 SkipDtorBB = CGF.createBasicBlock("nrvo.skipdtor"); 459 llvm::Value *DidNRVO = 460 CGF.Builder.CreateFlagLoad(NRVOFlag, "nrvo.val"); 461 CGF.Builder.CreateCondBr(DidNRVO, SkipDtorBB, RunDtorBB); 462 CGF.EmitBlock(RunDtorBB); 463 } 464 465 CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete, 466 /*ForVirtualBase=*/false, 467 /*Delegating=*/false, 468 Loc); 469 470 if (NRVO) CGF.EmitBlock(SkipDtorBB); 471 } 472 }; 473 474 struct CallStackRestore final : EHScopeStack::Cleanup { 475 Address Stack; 476 CallStackRestore(Address Stack) : Stack(Stack) {} 477 void Emit(CodeGenFunction &CGF, Flags flags) override { 478 llvm::Value *V = CGF.Builder.CreateLoad(Stack); 479 llvm::Value *F = CGF.CGM.getIntrinsic(llvm::Intrinsic::stackrestore); 480 CGF.Builder.CreateCall(F, V); 481 } 482 }; 483 484 struct ExtendGCLifetime final : EHScopeStack::Cleanup { 485 const VarDecl &Var; 486 ExtendGCLifetime(const VarDecl *var) : Var(*var) {} 487 488 void Emit(CodeGenFunction &CGF, Flags flags) override { 489 // Compute the address of the local variable, in case it's a 490 // byref or something. 491 DeclRefExpr DRE(const_cast<VarDecl*>(&Var), false, 492 Var.getType(), VK_LValue, SourceLocation()); 493 llvm::Value *value = CGF.EmitLoadOfScalar(CGF.EmitDeclRefLValue(&DRE), 494 SourceLocation()); 495 CGF.EmitExtendGCLifetime(value); 496 } 497 }; 498 499 struct CallCleanupFunction final : EHScopeStack::Cleanup { 500 llvm::Constant *CleanupFn; 501 const CGFunctionInfo &FnInfo; 502 const VarDecl &Var; 503 504 CallCleanupFunction(llvm::Constant *CleanupFn, const CGFunctionInfo *Info, 505 const VarDecl *Var) 506 : CleanupFn(CleanupFn), FnInfo(*Info), Var(*Var) {} 507 508 void Emit(CodeGenFunction &CGF, Flags flags) override { 509 DeclRefExpr DRE(const_cast<VarDecl*>(&Var), false, 510 Var.getType(), VK_LValue, SourceLocation()); 511 // Compute the address of the local variable, in case it's a byref 512 // or something. 513 llvm::Value *Addr = CGF.EmitDeclRefLValue(&DRE).getPointer(); 514 515 // In some cases, the type of the function argument will be different from 516 // the type of the pointer. An example of this is 517 // void f(void* arg); 518 // __attribute__((cleanup(f))) void *g; 519 // 520 // To fix this we insert a bitcast here. 521 QualType ArgTy = FnInfo.arg_begin()->type; 522 llvm::Value *Arg = 523 CGF.Builder.CreateBitCast(Addr, CGF.ConvertType(ArgTy)); 524 525 CallArgList Args; 526 Args.add(RValue::get(Arg), 527 CGF.getContext().getPointerType(Var.getType())); 528 CGF.EmitCall(FnInfo, CleanupFn, ReturnValueSlot(), Args); 529 } 530 }; 531 532 /// A cleanup to call @llvm.lifetime.end. 533 class CallLifetimeEnd final : public EHScopeStack::Cleanup { 534 llvm::Value *Addr; 535 llvm::Value *Size; 536 public: 537 CallLifetimeEnd(Address addr, llvm::Value *size) 538 : Addr(addr.getPointer()), Size(size) {} 539 540 void Emit(CodeGenFunction &CGF, Flags flags) override { 541 CGF.EmitLifetimeEnd(Size, Addr); 542 } 543 }; 544 } // end anonymous namespace 545 546 /// EmitAutoVarWithLifetime - Does the setup required for an automatic 547 /// variable with lifetime. 548 static void EmitAutoVarWithLifetime(CodeGenFunction &CGF, const VarDecl &var, 549 Address addr, 550 Qualifiers::ObjCLifetime lifetime) { 551 switch (lifetime) { 552 case Qualifiers::OCL_None: 553 llvm_unreachable("present but none"); 554 555 case Qualifiers::OCL_ExplicitNone: 556 // nothing to do 557 break; 558 559 case Qualifiers::OCL_Strong: { 560 CodeGenFunction::Destroyer *destroyer = 561 (var.hasAttr<ObjCPreciseLifetimeAttr>() 562 ? CodeGenFunction::destroyARCStrongPrecise 563 : CodeGenFunction::destroyARCStrongImprecise); 564 565 CleanupKind cleanupKind = CGF.getARCCleanupKind(); 566 CGF.pushDestroy(cleanupKind, addr, var.getType(), destroyer, 567 cleanupKind & EHCleanup); 568 break; 569 } 570 case Qualifiers::OCL_Autoreleasing: 571 // nothing to do 572 break; 573 574 case Qualifiers::OCL_Weak: 575 // __weak objects always get EH cleanups; otherwise, exceptions 576 // could cause really nasty crashes instead of mere leaks. 577 CGF.pushDestroy(NormalAndEHCleanup, addr, var.getType(), 578 CodeGenFunction::destroyARCWeak, 579 /*useEHCleanup*/ true); 580 break; 581 } 582 } 583 584 static bool isAccessedBy(const VarDecl &var, const Stmt *s) { 585 if (const Expr *e = dyn_cast<Expr>(s)) { 586 // Skip the most common kinds of expressions that make 587 // hierarchy-walking expensive. 588 s = e = e->IgnoreParenCasts(); 589 590 if (const DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e)) 591 return (ref->getDecl() == &var); 592 if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) { 593 const BlockDecl *block = be->getBlockDecl(); 594 for (const auto &I : block->captures()) { 595 if (I.getVariable() == &var) 596 return true; 597 } 598 } 599 } 600 601 for (const Stmt *SubStmt : s->children()) 602 // SubStmt might be null; as in missing decl or conditional of an if-stmt. 603 if (SubStmt && isAccessedBy(var, SubStmt)) 604 return true; 605 606 return false; 607 } 608 609 static bool isAccessedBy(const ValueDecl *decl, const Expr *e) { 610 if (!decl) return false; 611 if (!isa<VarDecl>(decl)) return false; 612 const VarDecl *var = cast<VarDecl>(decl); 613 return isAccessedBy(*var, e); 614 } 615 616 static bool tryEmitARCCopyWeakInit(CodeGenFunction &CGF, 617 const LValue &destLV, const Expr *init) { 618 bool needsCast = false; 619 620 while (auto castExpr = dyn_cast<CastExpr>(init->IgnoreParens())) { 621 switch (castExpr->getCastKind()) { 622 // Look through casts that don't require representation changes. 623 case CK_NoOp: 624 case CK_BitCast: 625 case CK_BlockPointerToObjCPointerCast: 626 needsCast = true; 627 break; 628 629 // If we find an l-value to r-value cast from a __weak variable, 630 // emit this operation as a copy or move. 631 case CK_LValueToRValue: { 632 const Expr *srcExpr = castExpr->getSubExpr(); 633 if (srcExpr->getType().getObjCLifetime() != Qualifiers::OCL_Weak) 634 return false; 635 636 // Emit the source l-value. 637 LValue srcLV = CGF.EmitLValue(srcExpr); 638 639 // Handle a formal type change to avoid asserting. 640 auto srcAddr = srcLV.getAddress(); 641 if (needsCast) { 642 srcAddr = CGF.Builder.CreateElementBitCast(srcAddr, 643 destLV.getAddress().getElementType()); 644 } 645 646 // If it was an l-value, use objc_copyWeak. 647 if (srcExpr->getValueKind() == VK_LValue) { 648 CGF.EmitARCCopyWeak(destLV.getAddress(), srcAddr); 649 } else { 650 assert(srcExpr->getValueKind() == VK_XValue); 651 CGF.EmitARCMoveWeak(destLV.getAddress(), srcAddr); 652 } 653 return true; 654 } 655 656 // Stop at anything else. 657 default: 658 return false; 659 } 660 661 init = castExpr->getSubExpr(); 662 } 663 return false; 664 } 665 666 static void drillIntoBlockVariable(CodeGenFunction &CGF, 667 LValue &lvalue, 668 const VarDecl *var) { 669 lvalue.setAddress(CGF.emitBlockByrefAddress(lvalue.getAddress(), var)); 670 } 671 672 void CodeGenFunction::EmitScalarInit(const Expr *init, const ValueDecl *D, 673 LValue lvalue, bool capturedByInit) { 674 Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime(); 675 if (!lifetime) { 676 llvm::Value *value = EmitScalarExpr(init); 677 if (capturedByInit) 678 drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 679 EmitStoreThroughLValue(RValue::get(value), lvalue, true); 680 return; 681 } 682 683 if (const CXXDefaultInitExpr *DIE = dyn_cast<CXXDefaultInitExpr>(init)) 684 init = DIE->getExpr(); 685 686 // If we're emitting a value with lifetime, we have to do the 687 // initialization *before* we leave the cleanup scopes. 688 if (const ExprWithCleanups *ewc = dyn_cast<ExprWithCleanups>(init)) { 689 enterFullExpression(ewc); 690 init = ewc->getSubExpr(); 691 } 692 CodeGenFunction::RunCleanupsScope Scope(*this); 693 694 // We have to maintain the illusion that the variable is 695 // zero-initialized. If the variable might be accessed in its 696 // initializer, zero-initialize before running the initializer, then 697 // actually perform the initialization with an assign. 698 bool accessedByInit = false; 699 if (lifetime != Qualifiers::OCL_ExplicitNone) 700 accessedByInit = (capturedByInit || isAccessedBy(D, init)); 701 if (accessedByInit) { 702 LValue tempLV = lvalue; 703 // Drill down to the __block object if necessary. 704 if (capturedByInit) { 705 // We can use a simple GEP for this because it can't have been 706 // moved yet. 707 tempLV.setAddress(emitBlockByrefAddress(tempLV.getAddress(), 708 cast<VarDecl>(D), 709 /*follow*/ false)); 710 } 711 712 auto ty = cast<llvm::PointerType>(tempLV.getAddress().getElementType()); 713 llvm::Value *zero = llvm::ConstantPointerNull::get(ty); 714 715 // If __weak, we want to use a barrier under certain conditions. 716 if (lifetime == Qualifiers::OCL_Weak) 717 EmitARCInitWeak(tempLV.getAddress(), zero); 718 719 // Otherwise just do a simple store. 720 else 721 EmitStoreOfScalar(zero, tempLV, /* isInitialization */ true); 722 } 723 724 // Emit the initializer. 725 llvm::Value *value = nullptr; 726 727 switch (lifetime) { 728 case Qualifiers::OCL_None: 729 llvm_unreachable("present but none"); 730 731 case Qualifiers::OCL_ExplicitNone: 732 value = EmitARCUnsafeUnretainedScalarExpr(init); 733 break; 734 735 case Qualifiers::OCL_Strong: { 736 value = EmitARCRetainScalarExpr(init); 737 break; 738 } 739 740 case Qualifiers::OCL_Weak: { 741 // If it's not accessed by the initializer, try to emit the 742 // initialization with a copy or move. 743 if (!accessedByInit && tryEmitARCCopyWeakInit(*this, lvalue, init)) { 744 return; 745 } 746 747 // No way to optimize a producing initializer into this. It's not 748 // worth optimizing for, because the value will immediately 749 // disappear in the common case. 750 value = EmitScalarExpr(init); 751 752 if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 753 if (accessedByInit) 754 EmitARCStoreWeak(lvalue.getAddress(), value, /*ignored*/ true); 755 else 756 EmitARCInitWeak(lvalue.getAddress(), value); 757 return; 758 } 759 760 case Qualifiers::OCL_Autoreleasing: 761 value = EmitARCRetainAutoreleaseScalarExpr(init); 762 break; 763 } 764 765 if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 766 767 // If the variable might have been accessed by its initializer, we 768 // might have to initialize with a barrier. We have to do this for 769 // both __weak and __strong, but __weak got filtered out above. 770 if (accessedByInit && lifetime == Qualifiers::OCL_Strong) { 771 llvm::Value *oldValue = EmitLoadOfScalar(lvalue, init->getExprLoc()); 772 EmitStoreOfScalar(value, lvalue, /* isInitialization */ true); 773 EmitARCRelease(oldValue, ARCImpreciseLifetime); 774 return; 775 } 776 777 EmitStoreOfScalar(value, lvalue, /* isInitialization */ true); 778 } 779 780 /// EmitScalarInit - Initialize the given lvalue with the given object. 781 void CodeGenFunction::EmitScalarInit(llvm::Value *init, LValue lvalue) { 782 Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime(); 783 if (!lifetime) 784 return EmitStoreThroughLValue(RValue::get(init), lvalue, true); 785 786 switch (lifetime) { 787 case Qualifiers::OCL_None: 788 llvm_unreachable("present but none"); 789 790 case Qualifiers::OCL_ExplicitNone: 791 // nothing to do 792 break; 793 794 case Qualifiers::OCL_Strong: 795 init = EmitARCRetain(lvalue.getType(), init); 796 break; 797 798 case Qualifiers::OCL_Weak: 799 // Initialize and then skip the primitive store. 800 EmitARCInitWeak(lvalue.getAddress(), init); 801 return; 802 803 case Qualifiers::OCL_Autoreleasing: 804 init = EmitARCRetainAutorelease(lvalue.getType(), init); 805 break; 806 } 807 808 EmitStoreOfScalar(init, lvalue, /* isInitialization */ true); 809 } 810 811 /// canEmitInitWithFewStoresAfterMemset - Decide whether we can emit the 812 /// non-zero parts of the specified initializer with equal or fewer than 813 /// NumStores scalar stores. 814 static bool canEmitInitWithFewStoresAfterMemset(llvm::Constant *Init, 815 unsigned &NumStores) { 816 // Zero and Undef never requires any extra stores. 817 if (isa<llvm::ConstantAggregateZero>(Init) || 818 isa<llvm::ConstantPointerNull>(Init) || 819 isa<llvm::UndefValue>(Init)) 820 return true; 821 if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) || 822 isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) || 823 isa<llvm::ConstantExpr>(Init)) 824 return Init->isNullValue() || NumStores--; 825 826 // See if we can emit each element. 827 if (isa<llvm::ConstantArray>(Init) || isa<llvm::ConstantStruct>(Init)) { 828 for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) { 829 llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i)); 830 if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores)) 831 return false; 832 } 833 return true; 834 } 835 836 if (llvm::ConstantDataSequential *CDS = 837 dyn_cast<llvm::ConstantDataSequential>(Init)) { 838 for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) { 839 llvm::Constant *Elt = CDS->getElementAsConstant(i); 840 if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores)) 841 return false; 842 } 843 return true; 844 } 845 846 // Anything else is hard and scary. 847 return false; 848 } 849 850 /// emitStoresForInitAfterMemset - For inits that 851 /// canEmitInitWithFewStoresAfterMemset returned true for, emit the scalar 852 /// stores that would be required. 853 static void emitStoresForInitAfterMemset(llvm::Constant *Init, llvm::Value *Loc, 854 bool isVolatile, CGBuilderTy &Builder) { 855 assert(!Init->isNullValue() && !isa<llvm::UndefValue>(Init) && 856 "called emitStoresForInitAfterMemset for zero or undef value."); 857 858 if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) || 859 isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) || 860 isa<llvm::ConstantExpr>(Init)) { 861 Builder.CreateDefaultAlignedStore(Init, Loc, isVolatile); 862 return; 863 } 864 865 if (llvm::ConstantDataSequential *CDS = 866 dyn_cast<llvm::ConstantDataSequential>(Init)) { 867 for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) { 868 llvm::Constant *Elt = CDS->getElementAsConstant(i); 869 870 // If necessary, get a pointer to the element and emit it. 871 if (!Elt->isNullValue() && !isa<llvm::UndefValue>(Elt)) 872 emitStoresForInitAfterMemset( 873 Elt, Builder.CreateConstGEP2_32(Init->getType(), Loc, 0, i), 874 isVolatile, Builder); 875 } 876 return; 877 } 878 879 assert((isa<llvm::ConstantStruct>(Init) || isa<llvm::ConstantArray>(Init)) && 880 "Unknown value type!"); 881 882 for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) { 883 llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i)); 884 885 // If necessary, get a pointer to the element and emit it. 886 if (!Elt->isNullValue() && !isa<llvm::UndefValue>(Elt)) 887 emitStoresForInitAfterMemset( 888 Elt, Builder.CreateConstGEP2_32(Init->getType(), Loc, 0, i), 889 isVolatile, Builder); 890 } 891 } 892 893 /// shouldUseMemSetPlusStoresToInitialize - Decide whether we should use memset 894 /// plus some stores to initialize a local variable instead of using a memcpy 895 /// from a constant global. It is beneficial to use memset if the global is all 896 /// zeros, or mostly zeros and large. 897 static bool shouldUseMemSetPlusStoresToInitialize(llvm::Constant *Init, 898 uint64_t GlobalSize) { 899 // If a global is all zeros, always use a memset. 900 if (isa<llvm::ConstantAggregateZero>(Init)) return true; 901 902 // If a non-zero global is <= 32 bytes, always use a memcpy. If it is large, 903 // do it if it will require 6 or fewer scalar stores. 904 // TODO: Should budget depends on the size? Avoiding a large global warrants 905 // plopping in more stores. 906 unsigned StoreBudget = 6; 907 uint64_t SizeLimit = 32; 908 909 return GlobalSize > SizeLimit && 910 canEmitInitWithFewStoresAfterMemset(Init, StoreBudget); 911 } 912 913 /// EmitAutoVarDecl - Emit code and set up an entry in LocalDeclMap for a 914 /// variable declaration with auto, register, or no storage class specifier. 915 /// These turn into simple stack objects, or GlobalValues depending on target. 916 void CodeGenFunction::EmitAutoVarDecl(const VarDecl &D) { 917 AutoVarEmission emission = EmitAutoVarAlloca(D); 918 EmitAutoVarInit(emission); 919 EmitAutoVarCleanups(emission); 920 } 921 922 /// Emit a lifetime.begin marker if some criteria are satisfied. 923 /// \return a pointer to the temporary size Value if a marker was emitted, null 924 /// otherwise 925 llvm::Value *CodeGenFunction::EmitLifetimeStart(uint64_t Size, 926 llvm::Value *Addr) { 927 // For now, only in optimized builds. 928 if (CGM.getCodeGenOpts().OptimizationLevel == 0) 929 return nullptr; 930 931 // Disable lifetime markers in msan builds. 932 // FIXME: Remove this when msan works with lifetime markers. 933 if (getLangOpts().Sanitize.has(SanitizerKind::Memory)) 934 return nullptr; 935 936 llvm::Value *SizeV = llvm::ConstantInt::get(Int64Ty, Size); 937 Addr = Builder.CreateBitCast(Addr, Int8PtrTy); 938 llvm::CallInst *C = 939 Builder.CreateCall(CGM.getLLVMLifetimeStartFn(), {SizeV, Addr}); 940 C->setDoesNotThrow(); 941 return SizeV; 942 } 943 944 void CodeGenFunction::EmitLifetimeEnd(llvm::Value *Size, llvm::Value *Addr) { 945 Addr = Builder.CreateBitCast(Addr, Int8PtrTy); 946 llvm::CallInst *C = 947 Builder.CreateCall(CGM.getLLVMLifetimeEndFn(), {Size, Addr}); 948 C->setDoesNotThrow(); 949 } 950 951 /// EmitAutoVarAlloca - Emit the alloca and debug information for a 952 /// local variable. Does not emit initialization or destruction. 953 CodeGenFunction::AutoVarEmission 954 CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) { 955 QualType Ty = D.getType(); 956 957 AutoVarEmission emission(D); 958 959 bool isByRef = D.hasAttr<BlocksAttr>(); 960 emission.IsByRef = isByRef; 961 962 CharUnits alignment = getContext().getDeclAlign(&D); 963 964 // If the type is variably-modified, emit all the VLA sizes for it. 965 if (Ty->isVariablyModifiedType()) 966 EmitVariablyModifiedType(Ty); 967 968 Address address = Address::invalid(); 969 if (Ty->isConstantSizeType()) { 970 bool NRVO = getLangOpts().ElideConstructors && 971 D.isNRVOVariable(); 972 973 // If this value is an array or struct with a statically determinable 974 // constant initializer, there are optimizations we can do. 975 // 976 // TODO: We should constant-evaluate the initializer of any variable, 977 // as long as it is initialized by a constant expression. Currently, 978 // isConstantInitializer produces wrong answers for structs with 979 // reference or bitfield members, and a few other cases, and checking 980 // for POD-ness protects us from some of these. 981 if (D.getInit() && (Ty->isArrayType() || Ty->isRecordType()) && 982 (D.isConstexpr() || 983 ((Ty.isPODType(getContext()) || 984 getContext().getBaseElementType(Ty)->isObjCObjectPointerType()) && 985 D.getInit()->isConstantInitializer(getContext(), false)))) { 986 987 // If the variable's a const type, and it's neither an NRVO 988 // candidate nor a __block variable and has no mutable members, 989 // emit it as a global instead. 990 if (CGM.getCodeGenOpts().MergeAllConstants && !NRVO && !isByRef && 991 CGM.isTypeConstant(Ty, true)) { 992 EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage); 993 994 // Signal this condition to later callbacks. 995 emission.Addr = Address::invalid(); 996 assert(emission.wasEmittedAsGlobal()); 997 return emission; 998 } 999 1000 // Otherwise, tell the initialization code that we're in this case. 1001 emission.IsConstantAggregate = true; 1002 } 1003 1004 // A normal fixed sized variable becomes an alloca in the entry block, 1005 // unless it's an NRVO variable. 1006 1007 if (NRVO) { 1008 // The named return value optimization: allocate this variable in the 1009 // return slot, so that we can elide the copy when returning this 1010 // variable (C++0x [class.copy]p34). 1011 address = ReturnValue; 1012 1013 if (const RecordType *RecordTy = Ty->getAs<RecordType>()) { 1014 if (!cast<CXXRecordDecl>(RecordTy->getDecl())->hasTrivialDestructor()) { 1015 // Create a flag that is used to indicate when the NRVO was applied 1016 // to this variable. Set it to zero to indicate that NRVO was not 1017 // applied. 1018 llvm::Value *Zero = Builder.getFalse(); 1019 Address NRVOFlag = 1020 CreateTempAlloca(Zero->getType(), CharUnits::One(), "nrvo"); 1021 EnsureInsertPoint(); 1022 Builder.CreateStore(Zero, NRVOFlag); 1023 1024 // Record the NRVO flag for this variable. 1025 NRVOFlags[&D] = NRVOFlag.getPointer(); 1026 emission.NRVOFlag = NRVOFlag.getPointer(); 1027 } 1028 } 1029 } else { 1030 CharUnits allocaAlignment; 1031 llvm::Type *allocaTy; 1032 if (isByRef) { 1033 auto &byrefInfo = getBlockByrefInfo(&D); 1034 allocaTy = byrefInfo.Type; 1035 allocaAlignment = byrefInfo.ByrefAlignment; 1036 } else { 1037 allocaTy = ConvertTypeForMem(Ty); 1038 allocaAlignment = alignment; 1039 } 1040 1041 // Create the alloca. Note that we set the name separately from 1042 // building the instruction so that it's there even in no-asserts 1043 // builds. 1044 address = CreateTempAlloca(allocaTy, allocaAlignment); 1045 address.getPointer()->setName(D.getName()); 1046 1047 // Don't emit lifetime markers for MSVC catch parameters. The lifetime of 1048 // the catch parameter starts in the catchpad instruction, and we can't 1049 // insert code in those basic blocks. 1050 bool IsMSCatchParam = 1051 D.isExceptionVariable() && getTarget().getCXXABI().isMicrosoft(); 1052 1053 // Emit a lifetime intrinsic if meaningful. There's no point 1054 // in doing this if we don't have a valid insertion point (?). 1055 if (HaveInsertPoint() && !IsMSCatchParam) { 1056 uint64_t size = CGM.getDataLayout().getTypeAllocSize(allocaTy); 1057 emission.SizeForLifetimeMarkers = 1058 EmitLifetimeStart(size, address.getPointer()); 1059 } else { 1060 assert(!emission.useLifetimeMarkers()); 1061 } 1062 } 1063 } else { 1064 EnsureInsertPoint(); 1065 1066 if (!DidCallStackSave) { 1067 // Save the stack. 1068 Address Stack = 1069 CreateTempAlloca(Int8PtrTy, getPointerAlign(), "saved_stack"); 1070 1071 llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave); 1072 llvm::Value *V = Builder.CreateCall(F); 1073 Builder.CreateStore(V, Stack); 1074 1075 DidCallStackSave = true; 1076 1077 // Push a cleanup block and restore the stack there. 1078 // FIXME: in general circumstances, this should be an EH cleanup. 1079 pushStackRestore(NormalCleanup, Stack); 1080 } 1081 1082 llvm::Value *elementCount; 1083 QualType elementType; 1084 std::tie(elementCount, elementType) = getVLASize(Ty); 1085 1086 llvm::Type *llvmTy = ConvertTypeForMem(elementType); 1087 1088 // Allocate memory for the array. 1089 llvm::AllocaInst *vla = Builder.CreateAlloca(llvmTy, elementCount, "vla"); 1090 vla->setAlignment(alignment.getQuantity()); 1091 1092 address = Address(vla, alignment); 1093 } 1094 1095 setAddrOfLocalVar(&D, address); 1096 emission.Addr = address; 1097 1098 // Emit debug info for local var declaration. 1099 if (HaveInsertPoint()) 1100 if (CGDebugInfo *DI = getDebugInfo()) { 1101 if (CGM.getCodeGenOpts().getDebugInfo() >= 1102 codegenoptions::LimitedDebugInfo) { 1103 DI->setLocation(D.getLocation()); 1104 DI->EmitDeclareOfAutoVariable(&D, address.getPointer(), Builder); 1105 } 1106 } 1107 1108 if (D.hasAttr<AnnotateAttr>()) 1109 EmitVarAnnotations(&D, address.getPointer()); 1110 1111 return emission; 1112 } 1113 1114 /// Determines whether the given __block variable is potentially 1115 /// captured by the given expression. 1116 static bool isCapturedBy(const VarDecl &var, const Expr *e) { 1117 // Skip the most common kinds of expressions that make 1118 // hierarchy-walking expensive. 1119 e = e->IgnoreParenCasts(); 1120 1121 if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) { 1122 const BlockDecl *block = be->getBlockDecl(); 1123 for (const auto &I : block->captures()) { 1124 if (I.getVariable() == &var) 1125 return true; 1126 } 1127 1128 // No need to walk into the subexpressions. 1129 return false; 1130 } 1131 1132 if (const StmtExpr *SE = dyn_cast<StmtExpr>(e)) { 1133 const CompoundStmt *CS = SE->getSubStmt(); 1134 for (const auto *BI : CS->body()) 1135 if (const auto *E = dyn_cast<Expr>(BI)) { 1136 if (isCapturedBy(var, E)) 1137 return true; 1138 } 1139 else if (const auto *DS = dyn_cast<DeclStmt>(BI)) { 1140 // special case declarations 1141 for (const auto *I : DS->decls()) { 1142 if (const auto *VD = dyn_cast<VarDecl>((I))) { 1143 const Expr *Init = VD->getInit(); 1144 if (Init && isCapturedBy(var, Init)) 1145 return true; 1146 } 1147 } 1148 } 1149 else 1150 // FIXME. Make safe assumption assuming arbitrary statements cause capturing. 1151 // Later, provide code to poke into statements for capture analysis. 1152 return true; 1153 return false; 1154 } 1155 1156 for (const Stmt *SubStmt : e->children()) 1157 if (isCapturedBy(var, cast<Expr>(SubStmt))) 1158 return true; 1159 1160 return false; 1161 } 1162 1163 /// \brief Determine whether the given initializer is trivial in the sense 1164 /// that it requires no code to be generated. 1165 bool CodeGenFunction::isTrivialInitializer(const Expr *Init) { 1166 if (!Init) 1167 return true; 1168 1169 if (const CXXConstructExpr *Construct = dyn_cast<CXXConstructExpr>(Init)) 1170 if (CXXConstructorDecl *Constructor = Construct->getConstructor()) 1171 if (Constructor->isTrivial() && 1172 Constructor->isDefaultConstructor() && 1173 !Construct->requiresZeroInitialization()) 1174 return true; 1175 1176 return false; 1177 } 1178 1179 void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) { 1180 assert(emission.Variable && "emission was not valid!"); 1181 1182 // If this was emitted as a global constant, we're done. 1183 if (emission.wasEmittedAsGlobal()) return; 1184 1185 const VarDecl &D = *emission.Variable; 1186 auto DL = ApplyDebugLocation::CreateDefaultArtificial(*this, D.getLocation()); 1187 QualType type = D.getType(); 1188 1189 // If this local has an initializer, emit it now. 1190 const Expr *Init = D.getInit(); 1191 1192 // If we are at an unreachable point, we don't need to emit the initializer 1193 // unless it contains a label. 1194 if (!HaveInsertPoint()) { 1195 if (!Init || !ContainsLabel(Init)) return; 1196 EnsureInsertPoint(); 1197 } 1198 1199 // Initialize the structure of a __block variable. 1200 if (emission.IsByRef) 1201 emitByrefStructureInit(emission); 1202 1203 if (isTrivialInitializer(Init)) 1204 return; 1205 1206 // Check whether this is a byref variable that's potentially 1207 // captured and moved by its own initializer. If so, we'll need to 1208 // emit the initializer first, then copy into the variable. 1209 bool capturedByInit = emission.IsByRef && isCapturedBy(D, Init); 1210 1211 Address Loc = 1212 capturedByInit ? emission.Addr : emission.getObjectAddress(*this); 1213 1214 llvm::Constant *constant = nullptr; 1215 if (emission.IsConstantAggregate || D.isConstexpr()) { 1216 assert(!capturedByInit && "constant init contains a capturing block?"); 1217 constant = CGM.EmitConstantInit(D, this); 1218 } 1219 1220 if (!constant) { 1221 LValue lv = MakeAddrLValue(Loc, type); 1222 lv.setNonGC(true); 1223 return EmitExprAsInit(Init, &D, lv, capturedByInit); 1224 } 1225 1226 if (!emission.IsConstantAggregate) { 1227 // For simple scalar/complex initialization, store the value directly. 1228 LValue lv = MakeAddrLValue(Loc, type); 1229 lv.setNonGC(true); 1230 return EmitStoreThroughLValue(RValue::get(constant), lv, true); 1231 } 1232 1233 // If this is a simple aggregate initialization, we can optimize it 1234 // in various ways. 1235 bool isVolatile = type.isVolatileQualified(); 1236 1237 llvm::Value *SizeVal = 1238 llvm::ConstantInt::get(IntPtrTy, 1239 getContext().getTypeSizeInChars(type).getQuantity()); 1240 1241 llvm::Type *BP = Int8PtrTy; 1242 if (Loc.getType() != BP) 1243 Loc = Builder.CreateBitCast(Loc, BP); 1244 1245 // If the initializer is all or mostly zeros, codegen with memset then do 1246 // a few stores afterward. 1247 if (shouldUseMemSetPlusStoresToInitialize(constant, 1248 CGM.getDataLayout().getTypeAllocSize(constant->getType()))) { 1249 Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, 0), SizeVal, 1250 isVolatile); 1251 // Zero and undef don't require a stores. 1252 if (!constant->isNullValue() && !isa<llvm::UndefValue>(constant)) { 1253 Loc = Builder.CreateBitCast(Loc, constant->getType()->getPointerTo()); 1254 emitStoresForInitAfterMemset(constant, Loc.getPointer(), 1255 isVolatile, Builder); 1256 } 1257 } else { 1258 // Otherwise, create a temporary global with the initializer then 1259 // memcpy from the global to the alloca. 1260 std::string Name = getStaticDeclName(CGM, D); 1261 llvm::GlobalVariable *GV = 1262 new llvm::GlobalVariable(CGM.getModule(), constant->getType(), true, 1263 llvm::GlobalValue::PrivateLinkage, 1264 constant, Name); 1265 GV->setAlignment(Loc.getAlignment().getQuantity()); 1266 GV->setUnnamedAddr(true); 1267 1268 Address SrcPtr = Address(GV, Loc.getAlignment()); 1269 if (SrcPtr.getType() != BP) 1270 SrcPtr = Builder.CreateBitCast(SrcPtr, BP); 1271 1272 Builder.CreateMemCpy(Loc, SrcPtr, SizeVal, isVolatile); 1273 } 1274 } 1275 1276 /// Emit an expression as an initializer for a variable at the given 1277 /// location. The expression is not necessarily the normal 1278 /// initializer for the variable, and the address is not necessarily 1279 /// its normal location. 1280 /// 1281 /// \param init the initializing expression 1282 /// \param var the variable to act as if we're initializing 1283 /// \param loc the address to initialize; its type is a pointer 1284 /// to the LLVM mapping of the variable's type 1285 /// \param alignment the alignment of the address 1286 /// \param capturedByInit true if the variable is a __block variable 1287 /// whose address is potentially changed by the initializer 1288 void CodeGenFunction::EmitExprAsInit(const Expr *init, const ValueDecl *D, 1289 LValue lvalue, bool capturedByInit) { 1290 QualType type = D->getType(); 1291 1292 if (type->isReferenceType()) { 1293 RValue rvalue = EmitReferenceBindingToExpr(init); 1294 if (capturedByInit) 1295 drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 1296 EmitStoreThroughLValue(rvalue, lvalue, true); 1297 return; 1298 } 1299 switch (getEvaluationKind(type)) { 1300 case TEK_Scalar: 1301 EmitScalarInit(init, D, lvalue, capturedByInit); 1302 return; 1303 case TEK_Complex: { 1304 ComplexPairTy complex = EmitComplexExpr(init); 1305 if (capturedByInit) 1306 drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 1307 EmitStoreOfComplex(complex, lvalue, /*init*/ true); 1308 return; 1309 } 1310 case TEK_Aggregate: 1311 if (type->isAtomicType()) { 1312 EmitAtomicInit(const_cast<Expr*>(init), lvalue); 1313 } else { 1314 // TODO: how can we delay here if D is captured by its initializer? 1315 EmitAggExpr(init, AggValueSlot::forLValue(lvalue, 1316 AggValueSlot::IsDestructed, 1317 AggValueSlot::DoesNotNeedGCBarriers, 1318 AggValueSlot::IsNotAliased)); 1319 } 1320 return; 1321 } 1322 llvm_unreachable("bad evaluation kind"); 1323 } 1324 1325 /// Enter a destroy cleanup for the given local variable. 1326 void CodeGenFunction::emitAutoVarTypeCleanup( 1327 const CodeGenFunction::AutoVarEmission &emission, 1328 QualType::DestructionKind dtorKind) { 1329 assert(dtorKind != QualType::DK_none); 1330 1331 // Note that for __block variables, we want to destroy the 1332 // original stack object, not the possibly forwarded object. 1333 Address addr = emission.getObjectAddress(*this); 1334 1335 const VarDecl *var = emission.Variable; 1336 QualType type = var->getType(); 1337 1338 CleanupKind cleanupKind = NormalAndEHCleanup; 1339 CodeGenFunction::Destroyer *destroyer = nullptr; 1340 1341 switch (dtorKind) { 1342 case QualType::DK_none: 1343 llvm_unreachable("no cleanup for trivially-destructible variable"); 1344 1345 case QualType::DK_cxx_destructor: 1346 // If there's an NRVO flag on the emission, we need a different 1347 // cleanup. 1348 if (emission.NRVOFlag) { 1349 assert(!type->isArrayType()); 1350 CXXDestructorDecl *dtor = type->getAsCXXRecordDecl()->getDestructor(); 1351 EHStack.pushCleanup<DestroyNRVOVariable>(cleanupKind, addr, 1352 dtor, emission.NRVOFlag); 1353 return; 1354 } 1355 break; 1356 1357 case QualType::DK_objc_strong_lifetime: 1358 // Suppress cleanups for pseudo-strong variables. 1359 if (var->isARCPseudoStrong()) return; 1360 1361 // Otherwise, consider whether to use an EH cleanup or not. 1362 cleanupKind = getARCCleanupKind(); 1363 1364 // Use the imprecise destroyer by default. 1365 if (!var->hasAttr<ObjCPreciseLifetimeAttr>()) 1366 destroyer = CodeGenFunction::destroyARCStrongImprecise; 1367 break; 1368 1369 case QualType::DK_objc_weak_lifetime: 1370 break; 1371 } 1372 1373 // If we haven't chosen a more specific destroyer, use the default. 1374 if (!destroyer) destroyer = getDestroyer(dtorKind); 1375 1376 // Use an EH cleanup in array destructors iff the destructor itself 1377 // is being pushed as an EH cleanup. 1378 bool useEHCleanup = (cleanupKind & EHCleanup); 1379 EHStack.pushCleanup<DestroyObject>(cleanupKind, addr, type, destroyer, 1380 useEHCleanup); 1381 } 1382 1383 void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) { 1384 assert(emission.Variable && "emission was not valid!"); 1385 1386 // If this was emitted as a global constant, we're done. 1387 if (emission.wasEmittedAsGlobal()) return; 1388 1389 // If we don't have an insertion point, we're done. Sema prevents 1390 // us from jumping into any of these scopes anyway. 1391 if (!HaveInsertPoint()) return; 1392 1393 const VarDecl &D = *emission.Variable; 1394 1395 // Make sure we call @llvm.lifetime.end. This needs to happen 1396 // *last*, so the cleanup needs to be pushed *first*. 1397 if (emission.useLifetimeMarkers()) { 1398 EHStack.pushCleanup<CallLifetimeEnd>(NormalAndEHCleanup, 1399 emission.getAllocatedAddress(), 1400 emission.getSizeForLifetimeMarkers()); 1401 EHCleanupScope &cleanup = cast<EHCleanupScope>(*EHStack.begin()); 1402 cleanup.setLifetimeMarker(); 1403 } 1404 1405 // Check the type for a cleanup. 1406 if (QualType::DestructionKind dtorKind = D.getType().isDestructedType()) 1407 emitAutoVarTypeCleanup(emission, dtorKind); 1408 1409 // In GC mode, honor objc_precise_lifetime. 1410 if (getLangOpts().getGC() != LangOptions::NonGC && 1411 D.hasAttr<ObjCPreciseLifetimeAttr>()) { 1412 EHStack.pushCleanup<ExtendGCLifetime>(NormalCleanup, &D); 1413 } 1414 1415 // Handle the cleanup attribute. 1416 if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) { 1417 const FunctionDecl *FD = CA->getFunctionDecl(); 1418 1419 llvm::Constant *F = CGM.GetAddrOfFunction(FD); 1420 assert(F && "Could not find function!"); 1421 1422 const CGFunctionInfo &Info = CGM.getTypes().arrangeFunctionDeclaration(FD); 1423 EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup, F, &Info, &D); 1424 } 1425 1426 // If this is a block variable, call _Block_object_destroy 1427 // (on the unforwarded address). 1428 if (emission.IsByRef) 1429 enterByrefCleanup(emission); 1430 } 1431 1432 CodeGenFunction::Destroyer * 1433 CodeGenFunction::getDestroyer(QualType::DestructionKind kind) { 1434 switch (kind) { 1435 case QualType::DK_none: llvm_unreachable("no destroyer for trivial dtor"); 1436 case QualType::DK_cxx_destructor: 1437 return destroyCXXObject; 1438 case QualType::DK_objc_strong_lifetime: 1439 return destroyARCStrongPrecise; 1440 case QualType::DK_objc_weak_lifetime: 1441 return destroyARCWeak; 1442 } 1443 llvm_unreachable("Unknown DestructionKind"); 1444 } 1445 1446 /// pushEHDestroy - Push the standard destructor for the given type as 1447 /// an EH-only cleanup. 1448 void CodeGenFunction::pushEHDestroy(QualType::DestructionKind dtorKind, 1449 Address addr, QualType type) { 1450 assert(dtorKind && "cannot push destructor for trivial type"); 1451 assert(needsEHCleanup(dtorKind)); 1452 1453 pushDestroy(EHCleanup, addr, type, getDestroyer(dtorKind), true); 1454 } 1455 1456 /// pushDestroy - Push the standard destructor for the given type as 1457 /// at least a normal cleanup. 1458 void CodeGenFunction::pushDestroy(QualType::DestructionKind dtorKind, 1459 Address addr, QualType type) { 1460 assert(dtorKind && "cannot push destructor for trivial type"); 1461 1462 CleanupKind cleanupKind = getCleanupKind(dtorKind); 1463 pushDestroy(cleanupKind, addr, type, getDestroyer(dtorKind), 1464 cleanupKind & EHCleanup); 1465 } 1466 1467 void CodeGenFunction::pushDestroy(CleanupKind cleanupKind, Address addr, 1468 QualType type, Destroyer *destroyer, 1469 bool useEHCleanupForArray) { 1470 pushFullExprCleanup<DestroyObject>(cleanupKind, addr, type, 1471 destroyer, useEHCleanupForArray); 1472 } 1473 1474 void CodeGenFunction::pushStackRestore(CleanupKind Kind, Address SPMem) { 1475 EHStack.pushCleanup<CallStackRestore>(Kind, SPMem); 1476 } 1477 1478 void CodeGenFunction::pushLifetimeExtendedDestroy( 1479 CleanupKind cleanupKind, Address addr, QualType type, 1480 Destroyer *destroyer, bool useEHCleanupForArray) { 1481 assert(!isInConditionalBranch() && 1482 "performing lifetime extension from within conditional"); 1483 1484 // Push an EH-only cleanup for the object now. 1485 // FIXME: When popping normal cleanups, we need to keep this EH cleanup 1486 // around in case a temporary's destructor throws an exception. 1487 if (cleanupKind & EHCleanup) 1488 EHStack.pushCleanup<DestroyObject>( 1489 static_cast<CleanupKind>(cleanupKind & ~NormalCleanup), addr, type, 1490 destroyer, useEHCleanupForArray); 1491 1492 // Remember that we need to push a full cleanup for the object at the 1493 // end of the full-expression. 1494 pushCleanupAfterFullExpr<DestroyObject>( 1495 cleanupKind, addr, type, destroyer, useEHCleanupForArray); 1496 } 1497 1498 /// emitDestroy - Immediately perform the destruction of the given 1499 /// object. 1500 /// 1501 /// \param addr - the address of the object; a type* 1502 /// \param type - the type of the object; if an array type, all 1503 /// objects are destroyed in reverse order 1504 /// \param destroyer - the function to call to destroy individual 1505 /// elements 1506 /// \param useEHCleanupForArray - whether an EH cleanup should be 1507 /// used when destroying array elements, in case one of the 1508 /// destructions throws an exception 1509 void CodeGenFunction::emitDestroy(Address addr, QualType type, 1510 Destroyer *destroyer, 1511 bool useEHCleanupForArray) { 1512 const ArrayType *arrayType = getContext().getAsArrayType(type); 1513 if (!arrayType) 1514 return destroyer(*this, addr, type); 1515 1516 llvm::Value *length = emitArrayLength(arrayType, type, addr); 1517 1518 CharUnits elementAlign = 1519 addr.getAlignment() 1520 .alignmentOfArrayElement(getContext().getTypeSizeInChars(type)); 1521 1522 // Normally we have to check whether the array is zero-length. 1523 bool checkZeroLength = true; 1524 1525 // But if the array length is constant, we can suppress that. 1526 if (llvm::ConstantInt *constLength = dyn_cast<llvm::ConstantInt>(length)) { 1527 // ...and if it's constant zero, we can just skip the entire thing. 1528 if (constLength->isZero()) return; 1529 checkZeroLength = false; 1530 } 1531 1532 llvm::Value *begin = addr.getPointer(); 1533 llvm::Value *end = Builder.CreateInBoundsGEP(begin, length); 1534 emitArrayDestroy(begin, end, type, elementAlign, destroyer, 1535 checkZeroLength, useEHCleanupForArray); 1536 } 1537 1538 /// emitArrayDestroy - Destroys all the elements of the given array, 1539 /// beginning from last to first. The array cannot be zero-length. 1540 /// 1541 /// \param begin - a type* denoting the first element of the array 1542 /// \param end - a type* denoting one past the end of the array 1543 /// \param elementType - the element type of the array 1544 /// \param destroyer - the function to call to destroy elements 1545 /// \param useEHCleanup - whether to push an EH cleanup to destroy 1546 /// the remaining elements in case the destruction of a single 1547 /// element throws 1548 void CodeGenFunction::emitArrayDestroy(llvm::Value *begin, 1549 llvm::Value *end, 1550 QualType elementType, 1551 CharUnits elementAlign, 1552 Destroyer *destroyer, 1553 bool checkZeroLength, 1554 bool useEHCleanup) { 1555 assert(!elementType->isArrayType()); 1556 1557 // The basic structure here is a do-while loop, because we don't 1558 // need to check for the zero-element case. 1559 llvm::BasicBlock *bodyBB = createBasicBlock("arraydestroy.body"); 1560 llvm::BasicBlock *doneBB = createBasicBlock("arraydestroy.done"); 1561 1562 if (checkZeroLength) { 1563 llvm::Value *isEmpty = Builder.CreateICmpEQ(begin, end, 1564 "arraydestroy.isempty"); 1565 Builder.CreateCondBr(isEmpty, doneBB, bodyBB); 1566 } 1567 1568 // Enter the loop body, making that address the current address. 1569 llvm::BasicBlock *entryBB = Builder.GetInsertBlock(); 1570 EmitBlock(bodyBB); 1571 llvm::PHINode *elementPast = 1572 Builder.CreatePHI(begin->getType(), 2, "arraydestroy.elementPast"); 1573 elementPast->addIncoming(end, entryBB); 1574 1575 // Shift the address back by one element. 1576 llvm::Value *negativeOne = llvm::ConstantInt::get(SizeTy, -1, true); 1577 llvm::Value *element = Builder.CreateInBoundsGEP(elementPast, negativeOne, 1578 "arraydestroy.element"); 1579 1580 if (useEHCleanup) 1581 pushRegularPartialArrayCleanup(begin, element, elementType, elementAlign, 1582 destroyer); 1583 1584 // Perform the actual destruction there. 1585 destroyer(*this, Address(element, elementAlign), elementType); 1586 1587 if (useEHCleanup) 1588 PopCleanupBlock(); 1589 1590 // Check whether we've reached the end. 1591 llvm::Value *done = Builder.CreateICmpEQ(element, begin, "arraydestroy.done"); 1592 Builder.CreateCondBr(done, doneBB, bodyBB); 1593 elementPast->addIncoming(element, Builder.GetInsertBlock()); 1594 1595 // Done. 1596 EmitBlock(doneBB); 1597 } 1598 1599 /// Perform partial array destruction as if in an EH cleanup. Unlike 1600 /// emitArrayDestroy, the element type here may still be an array type. 1601 static void emitPartialArrayDestroy(CodeGenFunction &CGF, 1602 llvm::Value *begin, llvm::Value *end, 1603 QualType type, CharUnits elementAlign, 1604 CodeGenFunction::Destroyer *destroyer) { 1605 // If the element type is itself an array, drill down. 1606 unsigned arrayDepth = 0; 1607 while (const ArrayType *arrayType = CGF.getContext().getAsArrayType(type)) { 1608 // VLAs don't require a GEP index to walk into. 1609 if (!isa<VariableArrayType>(arrayType)) 1610 arrayDepth++; 1611 type = arrayType->getElementType(); 1612 } 1613 1614 if (arrayDepth) { 1615 llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, 0); 1616 1617 SmallVector<llvm::Value*,4> gepIndices(arrayDepth+1, zero); 1618 begin = CGF.Builder.CreateInBoundsGEP(begin, gepIndices, "pad.arraybegin"); 1619 end = CGF.Builder.CreateInBoundsGEP(end, gepIndices, "pad.arrayend"); 1620 } 1621 1622 // Destroy the array. We don't ever need an EH cleanup because we 1623 // assume that we're in an EH cleanup ourselves, so a throwing 1624 // destructor causes an immediate terminate. 1625 CGF.emitArrayDestroy(begin, end, type, elementAlign, destroyer, 1626 /*checkZeroLength*/ true, /*useEHCleanup*/ false); 1627 } 1628 1629 namespace { 1630 /// RegularPartialArrayDestroy - a cleanup which performs a partial 1631 /// array destroy where the end pointer is regularly determined and 1632 /// does not need to be loaded from a local. 1633 class RegularPartialArrayDestroy final : public EHScopeStack::Cleanup { 1634 llvm::Value *ArrayBegin; 1635 llvm::Value *ArrayEnd; 1636 QualType ElementType; 1637 CodeGenFunction::Destroyer *Destroyer; 1638 CharUnits ElementAlign; 1639 public: 1640 RegularPartialArrayDestroy(llvm::Value *arrayBegin, llvm::Value *arrayEnd, 1641 QualType elementType, CharUnits elementAlign, 1642 CodeGenFunction::Destroyer *destroyer) 1643 : ArrayBegin(arrayBegin), ArrayEnd(arrayEnd), 1644 ElementType(elementType), Destroyer(destroyer), 1645 ElementAlign(elementAlign) {} 1646 1647 void Emit(CodeGenFunction &CGF, Flags flags) override { 1648 emitPartialArrayDestroy(CGF, ArrayBegin, ArrayEnd, 1649 ElementType, ElementAlign, Destroyer); 1650 } 1651 }; 1652 1653 /// IrregularPartialArrayDestroy - a cleanup which performs a 1654 /// partial array destroy where the end pointer is irregularly 1655 /// determined and must be loaded from a local. 1656 class IrregularPartialArrayDestroy final : public EHScopeStack::Cleanup { 1657 llvm::Value *ArrayBegin; 1658 Address ArrayEndPointer; 1659 QualType ElementType; 1660 CodeGenFunction::Destroyer *Destroyer; 1661 CharUnits ElementAlign; 1662 public: 1663 IrregularPartialArrayDestroy(llvm::Value *arrayBegin, 1664 Address arrayEndPointer, 1665 QualType elementType, 1666 CharUnits elementAlign, 1667 CodeGenFunction::Destroyer *destroyer) 1668 : ArrayBegin(arrayBegin), ArrayEndPointer(arrayEndPointer), 1669 ElementType(elementType), Destroyer(destroyer), 1670 ElementAlign(elementAlign) {} 1671 1672 void Emit(CodeGenFunction &CGF, Flags flags) override { 1673 llvm::Value *arrayEnd = CGF.Builder.CreateLoad(ArrayEndPointer); 1674 emitPartialArrayDestroy(CGF, ArrayBegin, arrayEnd, 1675 ElementType, ElementAlign, Destroyer); 1676 } 1677 }; 1678 } // end anonymous namespace 1679 1680 /// pushIrregularPartialArrayCleanup - Push an EH cleanup to destroy 1681 /// already-constructed elements of the given array. The cleanup 1682 /// may be popped with DeactivateCleanupBlock or PopCleanupBlock. 1683 /// 1684 /// \param elementType - the immediate element type of the array; 1685 /// possibly still an array type 1686 void CodeGenFunction::pushIrregularPartialArrayCleanup(llvm::Value *arrayBegin, 1687 Address arrayEndPointer, 1688 QualType elementType, 1689 CharUnits elementAlign, 1690 Destroyer *destroyer) { 1691 pushFullExprCleanup<IrregularPartialArrayDestroy>(EHCleanup, 1692 arrayBegin, arrayEndPointer, 1693 elementType, elementAlign, 1694 destroyer); 1695 } 1696 1697 /// pushRegularPartialArrayCleanup - Push an EH cleanup to destroy 1698 /// already-constructed elements of the given array. The cleanup 1699 /// may be popped with DeactivateCleanupBlock or PopCleanupBlock. 1700 /// 1701 /// \param elementType - the immediate element type of the array; 1702 /// possibly still an array type 1703 void CodeGenFunction::pushRegularPartialArrayCleanup(llvm::Value *arrayBegin, 1704 llvm::Value *arrayEnd, 1705 QualType elementType, 1706 CharUnits elementAlign, 1707 Destroyer *destroyer) { 1708 pushFullExprCleanup<RegularPartialArrayDestroy>(EHCleanup, 1709 arrayBegin, arrayEnd, 1710 elementType, elementAlign, 1711 destroyer); 1712 } 1713 1714 /// Lazily declare the @llvm.lifetime.start intrinsic. 1715 llvm::Constant *CodeGenModule::getLLVMLifetimeStartFn() { 1716 if (LifetimeStartFn) return LifetimeStartFn; 1717 LifetimeStartFn = llvm::Intrinsic::getDeclaration(&getModule(), 1718 llvm::Intrinsic::lifetime_start); 1719 return LifetimeStartFn; 1720 } 1721 1722 /// Lazily declare the @llvm.lifetime.end intrinsic. 1723 llvm::Constant *CodeGenModule::getLLVMLifetimeEndFn() { 1724 if (LifetimeEndFn) return LifetimeEndFn; 1725 LifetimeEndFn = llvm::Intrinsic::getDeclaration(&getModule(), 1726 llvm::Intrinsic::lifetime_end); 1727 return LifetimeEndFn; 1728 } 1729 1730 namespace { 1731 /// A cleanup to perform a release of an object at the end of a 1732 /// function. This is used to balance out the incoming +1 of a 1733 /// ns_consumed argument when we can't reasonably do that just by 1734 /// not doing the initial retain for a __block argument. 1735 struct ConsumeARCParameter final : EHScopeStack::Cleanup { 1736 ConsumeARCParameter(llvm::Value *param, 1737 ARCPreciseLifetime_t precise) 1738 : Param(param), Precise(precise) {} 1739 1740 llvm::Value *Param; 1741 ARCPreciseLifetime_t Precise; 1742 1743 void Emit(CodeGenFunction &CGF, Flags flags) override { 1744 CGF.EmitARCRelease(Param, Precise); 1745 } 1746 }; 1747 } // end anonymous namespace 1748 1749 /// Emit an alloca (or GlobalValue depending on target) 1750 /// for the specified parameter and set up LocalDeclMap. 1751 void CodeGenFunction::EmitParmDecl(const VarDecl &D, ParamValue Arg, 1752 unsigned ArgNo) { 1753 // FIXME: Why isn't ImplicitParamDecl a ParmVarDecl? 1754 assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) && 1755 "Invalid argument to EmitParmDecl"); 1756 1757 Arg.getAnyValue()->setName(D.getName()); 1758 1759 QualType Ty = D.getType(); 1760 1761 // Use better IR generation for certain implicit parameters. 1762 if (auto IPD = dyn_cast<ImplicitParamDecl>(&D)) { 1763 // The only implicit argument a block has is its literal. 1764 // We assume this is always passed directly. 1765 if (BlockInfo) { 1766 setBlockContextParameter(IPD, ArgNo, Arg.getDirectValue()); 1767 return; 1768 } 1769 } 1770 1771 Address DeclPtr = Address::invalid(); 1772 bool DoStore = false; 1773 bool IsScalar = hasScalarEvaluationKind(Ty); 1774 // If we already have a pointer to the argument, reuse the input pointer. 1775 if (Arg.isIndirect()) { 1776 DeclPtr = Arg.getIndirectAddress(); 1777 // If we have a prettier pointer type at this point, bitcast to that. 1778 unsigned AS = DeclPtr.getType()->getAddressSpace(); 1779 llvm::Type *IRTy = ConvertTypeForMem(Ty)->getPointerTo(AS); 1780 if (DeclPtr.getType() != IRTy) 1781 DeclPtr = Builder.CreateBitCast(DeclPtr, IRTy, D.getName()); 1782 1783 // Push a destructor cleanup for this parameter if the ABI requires it. 1784 // Don't push a cleanup in a thunk for a method that will also emit a 1785 // cleanup. 1786 if (!IsScalar && !CurFuncIsThunk && 1787 getTarget().getCXXABI().areArgsDestroyedLeftToRightInCallee()) { 1788 const CXXRecordDecl *RD = Ty->getAsCXXRecordDecl(); 1789 if (RD && RD->hasNonTrivialDestructor()) 1790 pushDestroy(QualType::DK_cxx_destructor, DeclPtr, Ty); 1791 } 1792 } else { 1793 // Otherwise, create a temporary to hold the value. 1794 DeclPtr = CreateMemTemp(Ty, getContext().getDeclAlign(&D), 1795 D.getName() + ".addr"); 1796 DoStore = true; 1797 } 1798 1799 llvm::Value *ArgVal = (DoStore ? Arg.getDirectValue() : nullptr); 1800 1801 LValue lv = MakeAddrLValue(DeclPtr, Ty); 1802 if (IsScalar) { 1803 Qualifiers qs = Ty.getQualifiers(); 1804 if (Qualifiers::ObjCLifetime lt = qs.getObjCLifetime()) { 1805 // We honor __attribute__((ns_consumed)) for types with lifetime. 1806 // For __strong, it's handled by just skipping the initial retain; 1807 // otherwise we have to balance out the initial +1 with an extra 1808 // cleanup to do the release at the end of the function. 1809 bool isConsumed = D.hasAttr<NSConsumedAttr>(); 1810 1811 // 'self' is always formally __strong, but if this is not an 1812 // init method then we don't want to retain it. 1813 if (D.isARCPseudoStrong()) { 1814 const ObjCMethodDecl *method = cast<ObjCMethodDecl>(CurCodeDecl); 1815 assert(&D == method->getSelfDecl()); 1816 assert(lt == Qualifiers::OCL_Strong); 1817 assert(qs.hasConst()); 1818 assert(method->getMethodFamily() != OMF_init); 1819 (void) method; 1820 lt = Qualifiers::OCL_ExplicitNone; 1821 } 1822 1823 if (lt == Qualifiers::OCL_Strong) { 1824 if (!isConsumed) { 1825 if (CGM.getCodeGenOpts().OptimizationLevel == 0) { 1826 // use objc_storeStrong(&dest, value) for retaining the 1827 // object. But first, store a null into 'dest' because 1828 // objc_storeStrong attempts to release its old value. 1829 llvm::Value *Null = CGM.EmitNullConstant(D.getType()); 1830 EmitStoreOfScalar(Null, lv, /* isInitialization */ true); 1831 EmitARCStoreStrongCall(lv.getAddress(), ArgVal, true); 1832 DoStore = false; 1833 } 1834 else 1835 // Don't use objc_retainBlock for block pointers, because we 1836 // don't want to Block_copy something just because we got it 1837 // as a parameter. 1838 ArgVal = EmitARCRetainNonBlock(ArgVal); 1839 } 1840 } else { 1841 // Push the cleanup for a consumed parameter. 1842 if (isConsumed) { 1843 ARCPreciseLifetime_t precise = (D.hasAttr<ObjCPreciseLifetimeAttr>() 1844 ? ARCPreciseLifetime : ARCImpreciseLifetime); 1845 EHStack.pushCleanup<ConsumeARCParameter>(getARCCleanupKind(), ArgVal, 1846 precise); 1847 } 1848 1849 if (lt == Qualifiers::OCL_Weak) { 1850 EmitARCInitWeak(DeclPtr, ArgVal); 1851 DoStore = false; // The weak init is a store, no need to do two. 1852 } 1853 } 1854 1855 // Enter the cleanup scope. 1856 EmitAutoVarWithLifetime(*this, D, DeclPtr, lt); 1857 } 1858 } 1859 1860 // Store the initial value into the alloca. 1861 if (DoStore) 1862 EmitStoreOfScalar(ArgVal, lv, /* isInitialization */ true); 1863 1864 setAddrOfLocalVar(&D, DeclPtr); 1865 1866 // Emit debug info for param declaration. 1867 if (CGDebugInfo *DI = getDebugInfo()) { 1868 if (CGM.getCodeGenOpts().getDebugInfo() >= 1869 codegenoptions::LimitedDebugInfo) { 1870 DI->EmitDeclareOfArgVariable(&D, DeclPtr.getPointer(), ArgNo, Builder); 1871 } 1872 } 1873 1874 if (D.hasAttr<AnnotateAttr>()) 1875 EmitVarAnnotations(&D, DeclPtr.getPointer()); 1876 } 1877 1878 void CodeGenModule::EmitOMPDeclareReduction(const OMPDeclareReductionDecl *D, 1879 CodeGenFunction *CGF) { 1880 if (!LangOpts.OpenMP || (!LangOpts.EmitAllDecls && !D->isUsed())) 1881 return; 1882 getOpenMPRuntime().emitUserDefinedReduction(CGF, D); 1883 } 1884