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