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 "CGDebugInfo.h" 15 #include "CodeGenFunction.h" 16 #include "CodeGenModule.h" 17 #include "CGOpenCLRuntime.h" 18 #include "clang/AST/ASTContext.h" 19 #include "clang/AST/CharUnits.h" 20 #include "clang/AST/Decl.h" 21 #include "clang/AST/DeclObjC.h" 22 #include "clang/Basic/SourceManager.h" 23 #include "clang/Basic/TargetInfo.h" 24 #include "clang/Frontend/CodeGenOptions.h" 25 #include "llvm/GlobalVariable.h" 26 #include "llvm/Intrinsics.h" 27 #include "llvm/Target/TargetData.h" 28 #include "llvm/Type.h" 29 using namespace clang; 30 using namespace CodeGen; 31 32 33 void CodeGenFunction::EmitDecl(const Decl &D) { 34 switch (D.getKind()) { 35 case Decl::TranslationUnit: 36 case Decl::Namespace: 37 case Decl::UnresolvedUsingTypename: 38 case Decl::ClassTemplateSpecialization: 39 case Decl::ClassTemplatePartialSpecialization: 40 case Decl::TemplateTypeParm: 41 case Decl::UnresolvedUsingValue: 42 case Decl::NonTypeTemplateParm: 43 case Decl::CXXMethod: 44 case Decl::CXXConstructor: 45 case Decl::CXXDestructor: 46 case Decl::CXXConversion: 47 case Decl::Field: 48 case Decl::IndirectField: 49 case Decl::ObjCIvar: 50 case Decl::ObjCAtDefsField: 51 case Decl::ParmVar: 52 case Decl::ImplicitParam: 53 case Decl::ClassTemplate: 54 case Decl::FunctionTemplate: 55 case Decl::TypeAliasTemplate: 56 case Decl::TemplateTemplateParm: 57 case Decl::ObjCMethod: 58 case Decl::ObjCCategory: 59 case Decl::ObjCProtocol: 60 case Decl::ObjCInterface: 61 case Decl::ObjCCategoryImpl: 62 case Decl::ObjCImplementation: 63 case Decl::ObjCProperty: 64 case Decl::ObjCCompatibleAlias: 65 case Decl::AccessSpec: 66 case Decl::LinkageSpec: 67 case Decl::ObjCPropertyImpl: 68 case Decl::FileScopeAsm: 69 case Decl::Friend: 70 case Decl::FriendTemplate: 71 case Decl::Block: 72 case Decl::ClassScopeFunctionSpecialization: 73 llvm_unreachable("Declaration should not be in declstmts!"); 74 case Decl::Function: // void X(); 75 case Decl::Record: // struct/union/class X; 76 case Decl::Enum: // enum X; 77 case Decl::EnumConstant: // enum ? { X = ? } 78 case Decl::CXXRecord: // struct/union/class X; [C++] 79 case Decl::Using: // using X; [C++] 80 case Decl::UsingShadow: 81 case Decl::UsingDirective: // using namespace X; [C++] 82 case Decl::NamespaceAlias: 83 case Decl::StaticAssert: // static_assert(X, ""); [C++0x] 84 case Decl::Label: // __label__ x; 85 case Decl::Import: 86 // None of these decls require codegen support. 87 return; 88 89 case Decl::Var: { 90 const VarDecl &VD = cast<VarDecl>(D); 91 assert(VD.isLocalVarDecl() && 92 "Should not see file-scope variables inside a function!"); 93 return EmitVarDecl(VD); 94 } 95 96 case Decl::Typedef: // typedef int X; 97 case Decl::TypeAlias: { // using X = int; [C++0x] 98 const TypedefNameDecl &TD = cast<TypedefNameDecl>(D); 99 QualType Ty = TD.getUnderlyingType(); 100 101 if (Ty->isVariablyModifiedType()) 102 EmitVariablyModifiedType(Ty); 103 } 104 } 105 } 106 107 /// EmitVarDecl - This method handles emission of any variable declaration 108 /// inside a function, including static vars etc. 109 void CodeGenFunction::EmitVarDecl(const VarDecl &D) { 110 switch (D.getStorageClass()) { 111 case SC_None: 112 case SC_Auto: 113 case SC_Register: 114 return EmitAutoVarDecl(D); 115 case SC_Static: { 116 llvm::GlobalValue::LinkageTypes Linkage = 117 llvm::GlobalValue::InternalLinkage; 118 119 // If the function definition has some sort of weak linkage, its 120 // static variables should also be weak so that they get properly 121 // uniqued. We can't do this in C, though, because there's no 122 // standard way to agree on which variables are the same (i.e. 123 // there's no mangling). 124 if (getContext().getLangOpts().CPlusPlus) 125 if (llvm::GlobalValue::isWeakForLinker(CurFn->getLinkage())) 126 Linkage = CurFn->getLinkage(); 127 128 return EmitStaticVarDecl(D, Linkage); 129 } 130 case SC_Extern: 131 case SC_PrivateExtern: 132 // Don't emit it now, allow it to be emitted lazily on its first use. 133 return; 134 case SC_OpenCLWorkGroupLocal: 135 return CGM.getOpenCLRuntime().EmitWorkGroupLocalVarDecl(*this, D); 136 } 137 138 llvm_unreachable("Unknown storage class"); 139 } 140 141 static std::string GetStaticDeclName(CodeGenFunction &CGF, const VarDecl &D, 142 const char *Separator) { 143 CodeGenModule &CGM = CGF.CGM; 144 if (CGF.getContext().getLangOpts().CPlusPlus) { 145 StringRef Name = CGM.getMangledName(&D); 146 return Name.str(); 147 } 148 149 std::string ContextName; 150 if (!CGF.CurFuncDecl) { 151 // Better be in a block declared in global scope. 152 const NamedDecl *ND = cast<NamedDecl>(&D); 153 const DeclContext *DC = ND->getDeclContext(); 154 if (const BlockDecl *BD = dyn_cast<BlockDecl>(DC)) { 155 MangleBuffer Name; 156 CGM.getBlockMangledName(GlobalDecl(), Name, BD); 157 ContextName = Name.getString(); 158 } 159 else 160 llvm_unreachable("Unknown context for block static var decl"); 161 } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CGF.CurFuncDecl)) { 162 StringRef Name = CGM.getMangledName(FD); 163 ContextName = Name.str(); 164 } else if (isa<ObjCMethodDecl>(CGF.CurFuncDecl)) 165 ContextName = CGF.CurFn->getName(); 166 else 167 llvm_unreachable("Unknown context for static var decl"); 168 169 return ContextName + Separator + D.getNameAsString(); 170 } 171 172 llvm::GlobalVariable * 173 CodeGenFunction::CreateStaticVarDecl(const VarDecl &D, 174 const char *Separator, 175 llvm::GlobalValue::LinkageTypes Linkage) { 176 QualType Ty = D.getType(); 177 assert(Ty->isConstantSizeType() && "VLAs can't be static"); 178 179 // Use the label if the variable is renamed with the asm-label extension. 180 std::string Name; 181 if (D.hasAttr<AsmLabelAttr>()) 182 Name = CGM.getMangledName(&D); 183 else 184 Name = GetStaticDeclName(*this, D, Separator); 185 186 llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(Ty); 187 llvm::GlobalVariable *GV = 188 new llvm::GlobalVariable(CGM.getModule(), LTy, 189 Ty.isConstant(getContext()), Linkage, 190 CGM.EmitNullConstant(D.getType()), Name, 0, 191 D.isThreadSpecified(), 192 CGM.getContext().getTargetAddressSpace(Ty)); 193 GV->setAlignment(getContext().getDeclAlign(&D).getQuantity()); 194 if (Linkage != llvm::GlobalValue::InternalLinkage) 195 GV->setVisibility(CurFn->getVisibility()); 196 return GV; 197 } 198 199 /// hasNontrivialDestruction - Determine whether a type's destruction is 200 /// non-trivial. If so, and the variable uses static initialization, we must 201 /// register its destructor to run on exit. 202 static bool hasNontrivialDestruction(QualType T) { 203 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl(); 204 return RD && !RD->hasTrivialDestructor(); 205 } 206 207 /// AddInitializerToStaticVarDecl - Add the initializer for 'D' to the 208 /// global variable that has already been created for it. If the initializer 209 /// has a different type than GV does, this may free GV and return a different 210 /// one. Otherwise it just returns GV. 211 llvm::GlobalVariable * 212 CodeGenFunction::AddInitializerToStaticVarDecl(const VarDecl &D, 213 llvm::GlobalVariable *GV) { 214 llvm::Constant *Init = CGM.EmitConstantInit(D, this); 215 216 // If constant emission failed, then this should be a C++ static 217 // initializer. 218 if (!Init) { 219 if (!getContext().getLangOpts().CPlusPlus) 220 CGM.ErrorUnsupported(D.getInit(), "constant l-value expression"); 221 else if (Builder.GetInsertBlock()) { 222 // Since we have a static initializer, this global variable can't 223 // be constant. 224 GV->setConstant(false); 225 226 EmitCXXGuardedInit(D, GV, /*PerformInit*/true); 227 } 228 return GV; 229 } 230 231 // The initializer may differ in type from the global. Rewrite 232 // the global to match the initializer. (We have to do this 233 // because some types, like unions, can't be completely represented 234 // in the LLVM type system.) 235 if (GV->getType()->getElementType() != Init->getType()) { 236 llvm::GlobalVariable *OldGV = GV; 237 238 GV = new llvm::GlobalVariable(CGM.getModule(), Init->getType(), 239 OldGV->isConstant(), 240 OldGV->getLinkage(), Init, "", 241 /*InsertBefore*/ OldGV, 242 D.isThreadSpecified(), 243 CGM.getContext().getTargetAddressSpace(D.getType())); 244 GV->setVisibility(OldGV->getVisibility()); 245 246 // Steal the name of the old global 247 GV->takeName(OldGV); 248 249 // Replace all uses of the old global with the new global 250 llvm::Constant *NewPtrForOldDecl = 251 llvm::ConstantExpr::getBitCast(GV, OldGV->getType()); 252 OldGV->replaceAllUsesWith(NewPtrForOldDecl); 253 254 // Erase the old global, since it is no longer used. 255 OldGV->eraseFromParent(); 256 } 257 258 GV->setConstant(CGM.isTypeConstant(D.getType(), true)); 259 GV->setInitializer(Init); 260 261 if (hasNontrivialDestruction(D.getType())) { 262 // We have a constant initializer, but a nontrivial destructor. We still 263 // need to perform a guarded "initialization" in order to register the 264 // destructor. 265 EmitCXXGuardedInit(D, GV, /*PerformInit*/false); 266 } 267 268 return GV; 269 } 270 271 void CodeGenFunction::EmitStaticVarDecl(const VarDecl &D, 272 llvm::GlobalValue::LinkageTypes Linkage) { 273 llvm::Value *&DMEntry = LocalDeclMap[&D]; 274 assert(DMEntry == 0 && "Decl already exists in localdeclmap!"); 275 276 // Check to see if we already have a global variable for this 277 // declaration. This can happen when double-emitting function 278 // bodies, e.g. with complete and base constructors. 279 llvm::Constant *addr = 280 CGM.getStaticLocalDeclAddress(&D); 281 282 llvm::GlobalVariable *var; 283 if (addr) { 284 var = cast<llvm::GlobalVariable>(addr->stripPointerCasts()); 285 } else { 286 addr = var = CreateStaticVarDecl(D, ".", Linkage); 287 } 288 289 // Store into LocalDeclMap before generating initializer to handle 290 // circular references. 291 DMEntry = addr; 292 CGM.setStaticLocalDeclAddress(&D, addr); 293 294 // We can't have a VLA here, but we can have a pointer to a VLA, 295 // even though that doesn't really make any sense. 296 // Make sure to evaluate VLA bounds now so that we have them for later. 297 if (D.getType()->isVariablyModifiedType()) 298 EmitVariablyModifiedType(D.getType()); 299 300 // Save the type in case adding the initializer forces a type change. 301 llvm::Type *expectedType = addr->getType(); 302 303 // If this value has an initializer, emit it. 304 if (D.getInit()) 305 var = AddInitializerToStaticVarDecl(D, var); 306 307 var->setAlignment(getContext().getDeclAlign(&D).getQuantity()); 308 309 if (D.hasAttr<AnnotateAttr>()) 310 CGM.AddGlobalAnnotations(&D, var); 311 312 if (const SectionAttr *SA = D.getAttr<SectionAttr>()) 313 var->setSection(SA->getName()); 314 315 if (D.hasAttr<UsedAttr>()) 316 CGM.AddUsedGlobal(var); 317 318 // We may have to cast the constant because of the initializer 319 // mismatch above. 320 // 321 // FIXME: It is really dangerous to store this in the map; if anyone 322 // RAUW's the GV uses of this constant will be invalid. 323 llvm::Constant *castedAddr = llvm::ConstantExpr::getBitCast(var, expectedType); 324 DMEntry = castedAddr; 325 CGM.setStaticLocalDeclAddress(&D, castedAddr); 326 327 // Emit global variable debug descriptor for static vars. 328 CGDebugInfo *DI = getDebugInfo(); 329 if (DI) { 330 DI->setLocation(D.getLocation()); 331 DI->EmitGlobalVariable(var, &D); 332 } 333 } 334 335 namespace { 336 struct DestroyObject : EHScopeStack::Cleanup { 337 DestroyObject(llvm::Value *addr, QualType type, 338 CodeGenFunction::Destroyer *destroyer, 339 bool useEHCleanupForArray) 340 : addr(addr), type(type), destroyer(destroyer), 341 useEHCleanupForArray(useEHCleanupForArray) {} 342 343 llvm::Value *addr; 344 QualType type; 345 CodeGenFunction::Destroyer *destroyer; 346 bool useEHCleanupForArray; 347 348 void Emit(CodeGenFunction &CGF, Flags flags) { 349 // Don't use an EH cleanup recursively from an EH cleanup. 350 bool useEHCleanupForArray = 351 flags.isForNormalCleanup() && this->useEHCleanupForArray; 352 353 CGF.emitDestroy(addr, type, destroyer, useEHCleanupForArray); 354 } 355 }; 356 357 struct DestroyNRVOVariable : EHScopeStack::Cleanup { 358 DestroyNRVOVariable(llvm::Value *addr, 359 const CXXDestructorDecl *Dtor, 360 llvm::Value *NRVOFlag) 361 : Dtor(Dtor), NRVOFlag(NRVOFlag), Loc(addr) {} 362 363 const CXXDestructorDecl *Dtor; 364 llvm::Value *NRVOFlag; 365 llvm::Value *Loc; 366 367 void Emit(CodeGenFunction &CGF, Flags flags) { 368 // Along the exceptions path we always execute the dtor. 369 bool NRVO = flags.isForNormalCleanup() && NRVOFlag; 370 371 llvm::BasicBlock *SkipDtorBB = 0; 372 if (NRVO) { 373 // If we exited via NRVO, we skip the destructor call. 374 llvm::BasicBlock *RunDtorBB = CGF.createBasicBlock("nrvo.unused"); 375 SkipDtorBB = CGF.createBasicBlock("nrvo.skipdtor"); 376 llvm::Value *DidNRVO = CGF.Builder.CreateLoad(NRVOFlag, "nrvo.val"); 377 CGF.Builder.CreateCondBr(DidNRVO, SkipDtorBB, RunDtorBB); 378 CGF.EmitBlock(RunDtorBB); 379 } 380 381 CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete, 382 /*ForVirtualBase=*/false, Loc); 383 384 if (NRVO) CGF.EmitBlock(SkipDtorBB); 385 } 386 }; 387 388 struct CallStackRestore : EHScopeStack::Cleanup { 389 llvm::Value *Stack; 390 CallStackRestore(llvm::Value *Stack) : Stack(Stack) {} 391 void Emit(CodeGenFunction &CGF, Flags flags) { 392 llvm::Value *V = CGF.Builder.CreateLoad(Stack); 393 llvm::Value *F = CGF.CGM.getIntrinsic(llvm::Intrinsic::stackrestore); 394 CGF.Builder.CreateCall(F, V); 395 } 396 }; 397 398 struct ExtendGCLifetime : EHScopeStack::Cleanup { 399 const VarDecl &Var; 400 ExtendGCLifetime(const VarDecl *var) : Var(*var) {} 401 402 void Emit(CodeGenFunction &CGF, Flags flags) { 403 // Compute the address of the local variable, in case it's a 404 // byref or something. 405 DeclRefExpr DRE(const_cast<VarDecl*>(&Var), false, 406 Var.getType(), VK_LValue, SourceLocation()); 407 llvm::Value *value = CGF.EmitLoadOfScalar(CGF.EmitDeclRefLValue(&DRE)); 408 CGF.EmitExtendGCLifetime(value); 409 } 410 }; 411 412 struct CallCleanupFunction : EHScopeStack::Cleanup { 413 llvm::Constant *CleanupFn; 414 const CGFunctionInfo &FnInfo; 415 const VarDecl &Var; 416 417 CallCleanupFunction(llvm::Constant *CleanupFn, const CGFunctionInfo *Info, 418 const VarDecl *Var) 419 : CleanupFn(CleanupFn), FnInfo(*Info), Var(*Var) {} 420 421 void Emit(CodeGenFunction &CGF, Flags flags) { 422 DeclRefExpr DRE(const_cast<VarDecl*>(&Var), false, 423 Var.getType(), VK_LValue, SourceLocation()); 424 // Compute the address of the local variable, in case it's a byref 425 // or something. 426 llvm::Value *Addr = CGF.EmitDeclRefLValue(&DRE).getAddress(); 427 428 // In some cases, the type of the function argument will be different from 429 // the type of the pointer. An example of this is 430 // void f(void* arg); 431 // __attribute__((cleanup(f))) void *g; 432 // 433 // To fix this we insert a bitcast here. 434 QualType ArgTy = FnInfo.arg_begin()->type; 435 llvm::Value *Arg = 436 CGF.Builder.CreateBitCast(Addr, CGF.ConvertType(ArgTy)); 437 438 CallArgList Args; 439 Args.add(RValue::get(Arg), 440 CGF.getContext().getPointerType(Var.getType())); 441 CGF.EmitCall(FnInfo, CleanupFn, ReturnValueSlot(), Args); 442 } 443 }; 444 } 445 446 /// EmitAutoVarWithLifetime - Does the setup required for an automatic 447 /// variable with lifetime. 448 static void EmitAutoVarWithLifetime(CodeGenFunction &CGF, const VarDecl &var, 449 llvm::Value *addr, 450 Qualifiers::ObjCLifetime lifetime) { 451 switch (lifetime) { 452 case Qualifiers::OCL_None: 453 llvm_unreachable("present but none"); 454 455 case Qualifiers::OCL_ExplicitNone: 456 // nothing to do 457 break; 458 459 case Qualifiers::OCL_Strong: { 460 CodeGenFunction::Destroyer *destroyer = 461 (var.hasAttr<ObjCPreciseLifetimeAttr>() 462 ? CodeGenFunction::destroyARCStrongPrecise 463 : CodeGenFunction::destroyARCStrongImprecise); 464 465 CleanupKind cleanupKind = CGF.getARCCleanupKind(); 466 CGF.pushDestroy(cleanupKind, addr, var.getType(), destroyer, 467 cleanupKind & EHCleanup); 468 break; 469 } 470 case Qualifiers::OCL_Autoreleasing: 471 // nothing to do 472 break; 473 474 case Qualifiers::OCL_Weak: 475 // __weak objects always get EH cleanups; otherwise, exceptions 476 // could cause really nasty crashes instead of mere leaks. 477 CGF.pushDestroy(NormalAndEHCleanup, addr, var.getType(), 478 CodeGenFunction::destroyARCWeak, 479 /*useEHCleanup*/ true); 480 break; 481 } 482 } 483 484 static bool isAccessedBy(const VarDecl &var, const Stmt *s) { 485 if (const Expr *e = dyn_cast<Expr>(s)) { 486 // Skip the most common kinds of expressions that make 487 // hierarchy-walking expensive. 488 s = e = e->IgnoreParenCasts(); 489 490 if (const DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e)) 491 return (ref->getDecl() == &var); 492 } 493 494 for (Stmt::const_child_range children = s->children(); children; ++children) 495 // children might be null; as in missing decl or conditional of an if-stmt. 496 if ((*children) && isAccessedBy(var, *children)) 497 return true; 498 499 return false; 500 } 501 502 static bool isAccessedBy(const ValueDecl *decl, const Expr *e) { 503 if (!decl) return false; 504 if (!isa<VarDecl>(decl)) return false; 505 const VarDecl *var = cast<VarDecl>(decl); 506 return isAccessedBy(*var, e); 507 } 508 509 static void drillIntoBlockVariable(CodeGenFunction &CGF, 510 LValue &lvalue, 511 const VarDecl *var) { 512 lvalue.setAddress(CGF.BuildBlockByrefAddress(lvalue.getAddress(), var)); 513 } 514 515 void CodeGenFunction::EmitScalarInit(const Expr *init, 516 const ValueDecl *D, 517 LValue lvalue, 518 bool capturedByInit) { 519 Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime(); 520 if (!lifetime) { 521 llvm::Value *value = EmitScalarExpr(init); 522 if (capturedByInit) 523 drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 524 EmitStoreThroughLValue(RValue::get(value), lvalue, true); 525 return; 526 } 527 528 // If we're emitting a value with lifetime, we have to do the 529 // initialization *before* we leave the cleanup scopes. 530 if (const ExprWithCleanups *ewc = dyn_cast<ExprWithCleanups>(init)) { 531 enterFullExpression(ewc); 532 init = ewc->getSubExpr(); 533 } 534 CodeGenFunction::RunCleanupsScope Scope(*this); 535 536 // We have to maintain the illusion that the variable is 537 // zero-initialized. If the variable might be accessed in its 538 // initializer, zero-initialize before running the initializer, then 539 // actually perform the initialization with an assign. 540 bool accessedByInit = false; 541 if (lifetime != Qualifiers::OCL_ExplicitNone) 542 accessedByInit = (capturedByInit || isAccessedBy(D, init)); 543 if (accessedByInit) { 544 LValue tempLV = lvalue; 545 // Drill down to the __block object if necessary. 546 if (capturedByInit) { 547 // We can use a simple GEP for this because it can't have been 548 // moved yet. 549 tempLV.setAddress(Builder.CreateStructGEP(tempLV.getAddress(), 550 getByRefValueLLVMField(cast<VarDecl>(D)))); 551 } 552 553 llvm::PointerType *ty 554 = cast<llvm::PointerType>(tempLV.getAddress()->getType()); 555 ty = cast<llvm::PointerType>(ty->getElementType()); 556 557 llvm::Value *zero = llvm::ConstantPointerNull::get(ty); 558 559 // If __weak, we want to use a barrier under certain conditions. 560 if (lifetime == Qualifiers::OCL_Weak) 561 EmitARCInitWeak(tempLV.getAddress(), zero); 562 563 // Otherwise just do a simple store. 564 else 565 EmitStoreOfScalar(zero, tempLV, /* isInitialization */ true); 566 } 567 568 // Emit the initializer. 569 llvm::Value *value = 0; 570 571 switch (lifetime) { 572 case Qualifiers::OCL_None: 573 llvm_unreachable("present but none"); 574 575 case Qualifiers::OCL_ExplicitNone: 576 // nothing to do 577 value = EmitScalarExpr(init); 578 break; 579 580 case Qualifiers::OCL_Strong: { 581 value = EmitARCRetainScalarExpr(init); 582 break; 583 } 584 585 case Qualifiers::OCL_Weak: { 586 // No way to optimize a producing initializer into this. It's not 587 // worth optimizing for, because the value will immediately 588 // disappear in the common case. 589 value = EmitScalarExpr(init); 590 591 if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 592 if (accessedByInit) 593 EmitARCStoreWeak(lvalue.getAddress(), value, /*ignored*/ true); 594 else 595 EmitARCInitWeak(lvalue.getAddress(), value); 596 return; 597 } 598 599 case Qualifiers::OCL_Autoreleasing: 600 value = EmitARCRetainAutoreleaseScalarExpr(init); 601 break; 602 } 603 604 if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 605 606 // If the variable might have been accessed by its initializer, we 607 // might have to initialize with a barrier. We have to do this for 608 // both __weak and __strong, but __weak got filtered out above. 609 if (accessedByInit && lifetime == Qualifiers::OCL_Strong) { 610 llvm::Value *oldValue = EmitLoadOfScalar(lvalue); 611 EmitStoreOfScalar(value, lvalue, /* isInitialization */ true); 612 EmitARCRelease(oldValue, /*precise*/ false); 613 return; 614 } 615 616 EmitStoreOfScalar(value, lvalue, /* isInitialization */ true); 617 } 618 619 /// EmitScalarInit - Initialize the given lvalue with the given object. 620 void CodeGenFunction::EmitScalarInit(llvm::Value *init, LValue lvalue) { 621 Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime(); 622 if (!lifetime) 623 return EmitStoreThroughLValue(RValue::get(init), lvalue, true); 624 625 switch (lifetime) { 626 case Qualifiers::OCL_None: 627 llvm_unreachable("present but none"); 628 629 case Qualifiers::OCL_ExplicitNone: 630 // nothing to do 631 break; 632 633 case Qualifiers::OCL_Strong: 634 init = EmitARCRetain(lvalue.getType(), init); 635 break; 636 637 case Qualifiers::OCL_Weak: 638 // Initialize and then skip the primitive store. 639 EmitARCInitWeak(lvalue.getAddress(), init); 640 return; 641 642 case Qualifiers::OCL_Autoreleasing: 643 init = EmitARCRetainAutorelease(lvalue.getType(), init); 644 break; 645 } 646 647 EmitStoreOfScalar(init, lvalue, /* isInitialization */ true); 648 } 649 650 /// canEmitInitWithFewStoresAfterMemset - Decide whether we can emit the 651 /// non-zero parts of the specified initializer with equal or fewer than 652 /// NumStores scalar stores. 653 static bool canEmitInitWithFewStoresAfterMemset(llvm::Constant *Init, 654 unsigned &NumStores) { 655 // Zero and Undef never requires any extra stores. 656 if (isa<llvm::ConstantAggregateZero>(Init) || 657 isa<llvm::ConstantPointerNull>(Init) || 658 isa<llvm::UndefValue>(Init)) 659 return true; 660 if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) || 661 isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) || 662 isa<llvm::ConstantExpr>(Init)) 663 return Init->isNullValue() || NumStores--; 664 665 // See if we can emit each element. 666 if (isa<llvm::ConstantArray>(Init) || isa<llvm::ConstantStruct>(Init)) { 667 for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) { 668 llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i)); 669 if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores)) 670 return false; 671 } 672 return true; 673 } 674 675 if (llvm::ConstantDataSequential *CDS = 676 dyn_cast<llvm::ConstantDataSequential>(Init)) { 677 for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) { 678 llvm::Constant *Elt = CDS->getElementAsConstant(i); 679 if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores)) 680 return false; 681 } 682 return true; 683 } 684 685 // Anything else is hard and scary. 686 return false; 687 } 688 689 /// emitStoresForInitAfterMemset - For inits that 690 /// canEmitInitWithFewStoresAfterMemset returned true for, emit the scalar 691 /// stores that would be required. 692 static void emitStoresForInitAfterMemset(llvm::Constant *Init, llvm::Value *Loc, 693 bool isVolatile, CGBuilderTy &Builder) { 694 // Zero doesn't require a store. 695 if (Init->isNullValue() || isa<llvm::UndefValue>(Init)) 696 return; 697 698 if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) || 699 isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) || 700 isa<llvm::ConstantExpr>(Init)) { 701 Builder.CreateStore(Init, Loc, isVolatile); 702 return; 703 } 704 705 if (llvm::ConstantDataSequential *CDS = 706 dyn_cast<llvm::ConstantDataSequential>(Init)) { 707 for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) { 708 llvm::Constant *Elt = CDS->getElementAsConstant(i); 709 710 // Get a pointer to the element and emit it. 711 emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i), 712 isVolatile, Builder); 713 } 714 return; 715 } 716 717 assert((isa<llvm::ConstantStruct>(Init) || isa<llvm::ConstantArray>(Init)) && 718 "Unknown value type!"); 719 720 for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) { 721 llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i)); 722 // Get a pointer to the element and emit it. 723 emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i), 724 isVolatile, Builder); 725 } 726 } 727 728 729 /// shouldUseMemSetPlusStoresToInitialize - Decide whether we should use memset 730 /// plus some stores to initialize a local variable instead of using a memcpy 731 /// from a constant global. It is beneficial to use memset if the global is all 732 /// zeros, or mostly zeros and large. 733 static bool shouldUseMemSetPlusStoresToInitialize(llvm::Constant *Init, 734 uint64_t GlobalSize) { 735 // If a global is all zeros, always use a memset. 736 if (isa<llvm::ConstantAggregateZero>(Init)) return true; 737 738 739 // If a non-zero global is <= 32 bytes, always use a memcpy. If it is large, 740 // do it if it will require 6 or fewer scalar stores. 741 // TODO: Should budget depends on the size? Avoiding a large global warrants 742 // plopping in more stores. 743 unsigned StoreBudget = 6; 744 uint64_t SizeLimit = 32; 745 746 return GlobalSize > SizeLimit && 747 canEmitInitWithFewStoresAfterMemset(Init, StoreBudget); 748 } 749 750 751 /// EmitAutoVarDecl - Emit code and set up an entry in LocalDeclMap for a 752 /// variable declaration with auto, register, or no storage class specifier. 753 /// These turn into simple stack objects, or GlobalValues depending on target. 754 void CodeGenFunction::EmitAutoVarDecl(const VarDecl &D) { 755 AutoVarEmission emission = EmitAutoVarAlloca(D); 756 EmitAutoVarInit(emission); 757 EmitAutoVarCleanups(emission); 758 } 759 760 /// EmitAutoVarAlloca - Emit the alloca and debug information for a 761 /// local variable. Does not emit initalization or destruction. 762 CodeGenFunction::AutoVarEmission 763 CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) { 764 QualType Ty = D.getType(); 765 766 AutoVarEmission emission(D); 767 768 bool isByRef = D.hasAttr<BlocksAttr>(); 769 emission.IsByRef = isByRef; 770 771 CharUnits alignment = getContext().getDeclAlign(&D); 772 emission.Alignment = alignment; 773 774 // If the type is variably-modified, emit all the VLA sizes for it. 775 if (Ty->isVariablyModifiedType()) 776 EmitVariablyModifiedType(Ty); 777 778 llvm::Value *DeclPtr; 779 if (Ty->isConstantSizeType()) { 780 if (!Target.useGlobalsForAutomaticVariables()) { 781 bool NRVO = getContext().getLangOpts().ElideConstructors && 782 D.isNRVOVariable(); 783 784 // If this value is a POD array or struct with a statically 785 // determinable constant initializer, there are optimizations we can do. 786 // 787 // TODO: We should constant-evaluate the initializer of any variable, 788 // as long as it is initialized by a constant expression. Currently, 789 // isConstantInitializer produces wrong answers for structs with 790 // reference or bitfield members, and a few other cases, and checking 791 // for POD-ness protects us from some of these. 792 if (D.getInit() && 793 (Ty->isArrayType() || Ty->isRecordType()) && 794 (Ty.isPODType(getContext()) || 795 getContext().getBaseElementType(Ty)->isObjCObjectPointerType()) && 796 D.getInit()->isConstantInitializer(getContext(), false)) { 797 798 // If the variable's a const type, and it's neither an NRVO 799 // candidate nor a __block variable and has no mutable members, 800 // emit it as a global instead. 801 if (CGM.getCodeGenOpts().MergeAllConstants && !NRVO && !isByRef && 802 CGM.isTypeConstant(Ty, true)) { 803 EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage); 804 805 emission.Address = 0; // signal this condition to later callbacks 806 assert(emission.wasEmittedAsGlobal()); 807 return emission; 808 } 809 810 // Otherwise, tell the initialization code that we're in this case. 811 emission.IsConstantAggregate = true; 812 } 813 814 // A normal fixed sized variable becomes an alloca in the entry block, 815 // unless it's an NRVO variable. 816 llvm::Type *LTy = ConvertTypeForMem(Ty); 817 818 if (NRVO) { 819 // The named return value optimization: allocate this variable in the 820 // return slot, so that we can elide the copy when returning this 821 // variable (C++0x [class.copy]p34). 822 DeclPtr = ReturnValue; 823 824 if (const RecordType *RecordTy = Ty->getAs<RecordType>()) { 825 if (!cast<CXXRecordDecl>(RecordTy->getDecl())->hasTrivialDestructor()) { 826 // Create a flag that is used to indicate when the NRVO was applied 827 // to this variable. Set it to zero to indicate that NRVO was not 828 // applied. 829 llvm::Value *Zero = Builder.getFalse(); 830 llvm::Value *NRVOFlag = CreateTempAlloca(Zero->getType(), "nrvo"); 831 EnsureInsertPoint(); 832 Builder.CreateStore(Zero, NRVOFlag); 833 834 // Record the NRVO flag for this variable. 835 NRVOFlags[&D] = NRVOFlag; 836 emission.NRVOFlag = NRVOFlag; 837 } 838 } 839 } else { 840 if (isByRef) 841 LTy = BuildByRefType(&D); 842 843 llvm::AllocaInst *Alloc = CreateTempAlloca(LTy); 844 Alloc->setName(D.getName()); 845 846 CharUnits allocaAlignment = alignment; 847 if (isByRef) 848 allocaAlignment = std::max(allocaAlignment, 849 getContext().toCharUnitsFromBits(Target.getPointerAlign(0))); 850 Alloc->setAlignment(allocaAlignment.getQuantity()); 851 DeclPtr = Alloc; 852 } 853 } else { 854 // Targets that don't support recursion emit locals as globals. 855 const char *Class = 856 D.getStorageClass() == SC_Register ? ".reg." : ".auto."; 857 DeclPtr = CreateStaticVarDecl(D, Class, 858 llvm::GlobalValue::InternalLinkage); 859 } 860 } else { 861 EnsureInsertPoint(); 862 863 if (!DidCallStackSave) { 864 // Save the stack. 865 llvm::Value *Stack = CreateTempAlloca(Int8PtrTy, "saved_stack"); 866 867 llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave); 868 llvm::Value *V = Builder.CreateCall(F); 869 870 Builder.CreateStore(V, Stack); 871 872 DidCallStackSave = true; 873 874 // Push a cleanup block and restore the stack there. 875 // FIXME: in general circumstances, this should be an EH cleanup. 876 EHStack.pushCleanup<CallStackRestore>(NormalCleanup, Stack); 877 } 878 879 llvm::Value *elementCount; 880 QualType elementType; 881 llvm::tie(elementCount, elementType) = getVLASize(Ty); 882 883 llvm::Type *llvmTy = ConvertTypeForMem(elementType); 884 885 // Allocate memory for the array. 886 llvm::AllocaInst *vla = Builder.CreateAlloca(llvmTy, elementCount, "vla"); 887 vla->setAlignment(alignment.getQuantity()); 888 889 DeclPtr = vla; 890 } 891 892 llvm::Value *&DMEntry = LocalDeclMap[&D]; 893 assert(DMEntry == 0 && "Decl already exists in localdeclmap!"); 894 DMEntry = DeclPtr; 895 emission.Address = DeclPtr; 896 897 // Emit debug info for local var declaration. 898 if (HaveInsertPoint()) 899 if (CGDebugInfo *DI = getDebugInfo()) { 900 DI->setLocation(D.getLocation()); 901 if (Target.useGlobalsForAutomaticVariables()) { 902 DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(DeclPtr), &D); 903 } else 904 DI->EmitDeclareOfAutoVariable(&D, DeclPtr, Builder); 905 } 906 907 if (D.hasAttr<AnnotateAttr>()) 908 EmitVarAnnotations(&D, emission.Address); 909 910 return emission; 911 } 912 913 /// Determines whether the given __block variable is potentially 914 /// captured by the given expression. 915 static bool isCapturedBy(const VarDecl &var, const Expr *e) { 916 // Skip the most common kinds of expressions that make 917 // hierarchy-walking expensive. 918 e = e->IgnoreParenCasts(); 919 920 if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) { 921 const BlockDecl *block = be->getBlockDecl(); 922 for (BlockDecl::capture_const_iterator i = block->capture_begin(), 923 e = block->capture_end(); i != e; ++i) { 924 if (i->getVariable() == &var) 925 return true; 926 } 927 928 // No need to walk into the subexpressions. 929 return false; 930 } 931 932 if (const StmtExpr *SE = dyn_cast<StmtExpr>(e)) { 933 const CompoundStmt *CS = SE->getSubStmt(); 934 for (CompoundStmt::const_body_iterator BI = CS->body_begin(), 935 BE = CS->body_end(); BI != BE; ++BI) 936 if (Expr *E = dyn_cast<Expr>((*BI))) { 937 if (isCapturedBy(var, E)) 938 return true; 939 } 940 else if (DeclStmt *DS = dyn_cast<DeclStmt>((*BI))) { 941 // special case declarations 942 for (DeclStmt::decl_iterator I = DS->decl_begin(), E = DS->decl_end(); 943 I != E; ++I) { 944 if (VarDecl *VD = dyn_cast<VarDecl>((*I))) { 945 Expr *Init = VD->getInit(); 946 if (Init && isCapturedBy(var, Init)) 947 return true; 948 } 949 } 950 } 951 else 952 // FIXME. Make safe assumption assuming arbitrary statements cause capturing. 953 // Later, provide code to poke into statements for capture analysis. 954 return true; 955 return false; 956 } 957 958 for (Stmt::const_child_range children = e->children(); children; ++children) 959 if (isCapturedBy(var, cast<Expr>(*children))) 960 return true; 961 962 return false; 963 } 964 965 /// \brief Determine whether the given initializer is trivial in the sense 966 /// that it requires no code to be generated. 967 static bool isTrivialInitializer(const Expr *Init) { 968 if (!Init) 969 return true; 970 971 if (const CXXConstructExpr *Construct = dyn_cast<CXXConstructExpr>(Init)) 972 if (CXXConstructorDecl *Constructor = Construct->getConstructor()) 973 if (Constructor->isTrivial() && 974 Constructor->isDefaultConstructor() && 975 !Construct->requiresZeroInitialization()) 976 return true; 977 978 return false; 979 } 980 void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) { 981 assert(emission.Variable && "emission was not valid!"); 982 983 // If this was emitted as a global constant, we're done. 984 if (emission.wasEmittedAsGlobal()) return; 985 986 const VarDecl &D = *emission.Variable; 987 QualType type = D.getType(); 988 989 // If this local has an initializer, emit it now. 990 const Expr *Init = D.getInit(); 991 992 // If we are at an unreachable point, we don't need to emit the initializer 993 // unless it contains a label. 994 if (!HaveInsertPoint()) { 995 if (!Init || !ContainsLabel(Init)) return; 996 EnsureInsertPoint(); 997 } 998 999 // Initialize the structure of a __block variable. 1000 if (emission.IsByRef) 1001 emitByrefStructureInit(emission); 1002 1003 if (isTrivialInitializer(Init)) 1004 return; 1005 1006 CharUnits alignment = emission.Alignment; 1007 1008 // Check whether this is a byref variable that's potentially 1009 // captured and moved by its own initializer. If so, we'll need to 1010 // emit the initializer first, then copy into the variable. 1011 bool capturedByInit = emission.IsByRef && isCapturedBy(D, Init); 1012 1013 llvm::Value *Loc = 1014 capturedByInit ? emission.Address : emission.getObjectAddress(*this); 1015 1016 llvm::Constant *constant = 0; 1017 if (emission.IsConstantAggregate) { 1018 assert(!capturedByInit && "constant init contains a capturing block?"); 1019 constant = CGM.EmitConstantInit(D, this); 1020 } 1021 1022 if (!constant) { 1023 LValue lv = MakeAddrLValue(Loc, type, alignment); 1024 lv.setNonGC(true); 1025 return EmitExprAsInit(Init, &D, lv, capturedByInit); 1026 } 1027 1028 // If this is a simple aggregate initialization, we can optimize it 1029 // in various ways. 1030 bool isVolatile = type.isVolatileQualified(); 1031 1032 llvm::Value *SizeVal = 1033 llvm::ConstantInt::get(IntPtrTy, 1034 getContext().getTypeSizeInChars(type).getQuantity()); 1035 1036 llvm::Type *BP = Int8PtrTy; 1037 if (Loc->getType() != BP) 1038 Loc = Builder.CreateBitCast(Loc, BP); 1039 1040 // If the initializer is all or mostly zeros, codegen with memset then do 1041 // a few stores afterward. 1042 if (shouldUseMemSetPlusStoresToInitialize(constant, 1043 CGM.getTargetData().getTypeAllocSize(constant->getType()))) { 1044 Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, 0), SizeVal, 1045 alignment.getQuantity(), isVolatile); 1046 if (!constant->isNullValue()) { 1047 Loc = Builder.CreateBitCast(Loc, constant->getType()->getPointerTo()); 1048 emitStoresForInitAfterMemset(constant, Loc, isVolatile, Builder); 1049 } 1050 } else { 1051 // Otherwise, create a temporary global with the initializer then 1052 // memcpy from the global to the alloca. 1053 std::string Name = GetStaticDeclName(*this, D, "."); 1054 llvm::GlobalVariable *GV = 1055 new llvm::GlobalVariable(CGM.getModule(), constant->getType(), true, 1056 llvm::GlobalValue::PrivateLinkage, 1057 constant, Name, 0, false, 0); 1058 GV->setAlignment(alignment.getQuantity()); 1059 GV->setUnnamedAddr(true); 1060 1061 llvm::Value *SrcPtr = GV; 1062 if (SrcPtr->getType() != BP) 1063 SrcPtr = Builder.CreateBitCast(SrcPtr, BP); 1064 1065 Builder.CreateMemCpy(Loc, SrcPtr, SizeVal, alignment.getQuantity(), 1066 isVolatile); 1067 } 1068 } 1069 1070 /// Emit an expression as an initializer for a variable at the given 1071 /// location. The expression is not necessarily the normal 1072 /// initializer for the variable, and the address is not necessarily 1073 /// its normal location. 1074 /// 1075 /// \param init the initializing expression 1076 /// \param var the variable to act as if we're initializing 1077 /// \param loc the address to initialize; its type is a pointer 1078 /// to the LLVM mapping of the variable's type 1079 /// \param alignment the alignment of the address 1080 /// \param capturedByInit true if the variable is a __block variable 1081 /// whose address is potentially changed by the initializer 1082 void CodeGenFunction::EmitExprAsInit(const Expr *init, 1083 const ValueDecl *D, 1084 LValue lvalue, 1085 bool capturedByInit) { 1086 QualType type = D->getType(); 1087 1088 if (type->isReferenceType()) { 1089 RValue rvalue = EmitReferenceBindingToExpr(init, D); 1090 if (capturedByInit) 1091 drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 1092 EmitStoreThroughLValue(rvalue, lvalue, true); 1093 } else if (!hasAggregateLLVMType(type)) { 1094 EmitScalarInit(init, D, lvalue, capturedByInit); 1095 } else if (type->isAnyComplexType()) { 1096 ComplexPairTy complex = EmitComplexExpr(init); 1097 if (capturedByInit) 1098 drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 1099 StoreComplexToAddr(complex, lvalue.getAddress(), lvalue.isVolatile()); 1100 } else { 1101 // TODO: how can we delay here if D is captured by its initializer? 1102 EmitAggExpr(init, AggValueSlot::forLValue(lvalue, 1103 AggValueSlot::IsDestructed, 1104 AggValueSlot::DoesNotNeedGCBarriers, 1105 AggValueSlot::IsNotAliased)); 1106 MaybeEmitStdInitializerListCleanup(lvalue.getAddress(), init); 1107 } 1108 } 1109 1110 /// Enter a destroy cleanup for the given local variable. 1111 void CodeGenFunction::emitAutoVarTypeCleanup( 1112 const CodeGenFunction::AutoVarEmission &emission, 1113 QualType::DestructionKind dtorKind) { 1114 assert(dtorKind != QualType::DK_none); 1115 1116 // Note that for __block variables, we want to destroy the 1117 // original stack object, not the possibly forwarded object. 1118 llvm::Value *addr = emission.getObjectAddress(*this); 1119 1120 const VarDecl *var = emission.Variable; 1121 QualType type = var->getType(); 1122 1123 CleanupKind cleanupKind = NormalAndEHCleanup; 1124 CodeGenFunction::Destroyer *destroyer = 0; 1125 1126 switch (dtorKind) { 1127 case QualType::DK_none: 1128 llvm_unreachable("no cleanup for trivially-destructible variable"); 1129 1130 case QualType::DK_cxx_destructor: 1131 // If there's an NRVO flag on the emission, we need a different 1132 // cleanup. 1133 if (emission.NRVOFlag) { 1134 assert(!type->isArrayType()); 1135 CXXDestructorDecl *dtor = type->getAsCXXRecordDecl()->getDestructor(); 1136 EHStack.pushCleanup<DestroyNRVOVariable>(cleanupKind, addr, dtor, 1137 emission.NRVOFlag); 1138 return; 1139 } 1140 break; 1141 1142 case QualType::DK_objc_strong_lifetime: 1143 // Suppress cleanups for pseudo-strong variables. 1144 if (var->isARCPseudoStrong()) return; 1145 1146 // Otherwise, consider whether to use an EH cleanup or not. 1147 cleanupKind = getARCCleanupKind(); 1148 1149 // Use the imprecise destroyer by default. 1150 if (!var->hasAttr<ObjCPreciseLifetimeAttr>()) 1151 destroyer = CodeGenFunction::destroyARCStrongImprecise; 1152 break; 1153 1154 case QualType::DK_objc_weak_lifetime: 1155 break; 1156 } 1157 1158 // If we haven't chosen a more specific destroyer, use the default. 1159 if (!destroyer) destroyer = getDestroyer(dtorKind); 1160 1161 // Use an EH cleanup in array destructors iff the destructor itself 1162 // is being pushed as an EH cleanup. 1163 bool useEHCleanup = (cleanupKind & EHCleanup); 1164 EHStack.pushCleanup<DestroyObject>(cleanupKind, addr, type, destroyer, 1165 useEHCleanup); 1166 } 1167 1168 void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) { 1169 assert(emission.Variable && "emission was not valid!"); 1170 1171 // If this was emitted as a global constant, we're done. 1172 if (emission.wasEmittedAsGlobal()) return; 1173 1174 // If we don't have an insertion point, we're done. Sema prevents 1175 // us from jumping into any of these scopes anyway. 1176 if (!HaveInsertPoint()) return; 1177 1178 const VarDecl &D = *emission.Variable; 1179 1180 // Check the type for a cleanup. 1181 if (QualType::DestructionKind dtorKind = D.getType().isDestructedType()) 1182 emitAutoVarTypeCleanup(emission, dtorKind); 1183 1184 // In GC mode, honor objc_precise_lifetime. 1185 if (getLangOpts().getGC() != LangOptions::NonGC && 1186 D.hasAttr<ObjCPreciseLifetimeAttr>()) { 1187 EHStack.pushCleanup<ExtendGCLifetime>(NormalCleanup, &D); 1188 } 1189 1190 // Handle the cleanup attribute. 1191 if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) { 1192 const FunctionDecl *FD = CA->getFunctionDecl(); 1193 1194 llvm::Constant *F = CGM.GetAddrOfFunction(FD); 1195 assert(F && "Could not find function!"); 1196 1197 const CGFunctionInfo &Info = CGM.getTypes().arrangeFunctionDeclaration(FD); 1198 EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup, F, &Info, &D); 1199 } 1200 1201 // If this is a block variable, call _Block_object_destroy 1202 // (on the unforwarded address). 1203 if (emission.IsByRef) 1204 enterByrefCleanup(emission); 1205 } 1206 1207 CodeGenFunction::Destroyer * 1208 CodeGenFunction::getDestroyer(QualType::DestructionKind kind) { 1209 switch (kind) { 1210 case QualType::DK_none: llvm_unreachable("no destroyer for trivial dtor"); 1211 case QualType::DK_cxx_destructor: 1212 return destroyCXXObject; 1213 case QualType::DK_objc_strong_lifetime: 1214 return destroyARCStrongPrecise; 1215 case QualType::DK_objc_weak_lifetime: 1216 return destroyARCWeak; 1217 } 1218 llvm_unreachable("Unknown DestructionKind"); 1219 } 1220 1221 /// pushDestroy - Push the standard destructor for the given type. 1222 void CodeGenFunction::pushDestroy(QualType::DestructionKind dtorKind, 1223 llvm::Value *addr, QualType type) { 1224 assert(dtorKind && "cannot push destructor for trivial type"); 1225 1226 CleanupKind cleanupKind = getCleanupKind(dtorKind); 1227 pushDestroy(cleanupKind, addr, type, getDestroyer(dtorKind), 1228 cleanupKind & EHCleanup); 1229 } 1230 1231 void CodeGenFunction::pushDestroy(CleanupKind cleanupKind, llvm::Value *addr, 1232 QualType type, Destroyer *destroyer, 1233 bool useEHCleanupForArray) { 1234 pushFullExprCleanup<DestroyObject>(cleanupKind, addr, type, 1235 destroyer, useEHCleanupForArray); 1236 } 1237 1238 /// emitDestroy - Immediately perform the destruction of the given 1239 /// object. 1240 /// 1241 /// \param addr - the address of the object; a type* 1242 /// \param type - the type of the object; if an array type, all 1243 /// objects are destroyed in reverse order 1244 /// \param destroyer - the function to call to destroy individual 1245 /// elements 1246 /// \param useEHCleanupForArray - whether an EH cleanup should be 1247 /// used when destroying array elements, in case one of the 1248 /// destructions throws an exception 1249 void CodeGenFunction::emitDestroy(llvm::Value *addr, QualType type, 1250 Destroyer *destroyer, 1251 bool useEHCleanupForArray) { 1252 const ArrayType *arrayType = getContext().getAsArrayType(type); 1253 if (!arrayType) 1254 return destroyer(*this, addr, type); 1255 1256 llvm::Value *begin = addr; 1257 llvm::Value *length = emitArrayLength(arrayType, type, begin); 1258 1259 // Normally we have to check whether the array is zero-length. 1260 bool checkZeroLength = true; 1261 1262 // But if the array length is constant, we can suppress that. 1263 if (llvm::ConstantInt *constLength = dyn_cast<llvm::ConstantInt>(length)) { 1264 // ...and if it's constant zero, we can just skip the entire thing. 1265 if (constLength->isZero()) return; 1266 checkZeroLength = false; 1267 } 1268 1269 llvm::Value *end = Builder.CreateInBoundsGEP(begin, length); 1270 emitArrayDestroy(begin, end, type, destroyer, 1271 checkZeroLength, useEHCleanupForArray); 1272 } 1273 1274 /// emitArrayDestroy - Destroys all the elements of the given array, 1275 /// beginning from last to first. The array cannot be zero-length. 1276 /// 1277 /// \param begin - a type* denoting the first element of the array 1278 /// \param end - a type* denoting one past the end of the array 1279 /// \param type - the element type of the array 1280 /// \param destroyer - the function to call to destroy elements 1281 /// \param useEHCleanup - whether to push an EH cleanup to destroy 1282 /// the remaining elements in case the destruction of a single 1283 /// element throws 1284 void CodeGenFunction::emitArrayDestroy(llvm::Value *begin, 1285 llvm::Value *end, 1286 QualType type, 1287 Destroyer *destroyer, 1288 bool checkZeroLength, 1289 bool useEHCleanup) { 1290 assert(!type->isArrayType()); 1291 1292 // The basic structure here is a do-while loop, because we don't 1293 // need to check for the zero-element case. 1294 llvm::BasicBlock *bodyBB = createBasicBlock("arraydestroy.body"); 1295 llvm::BasicBlock *doneBB = createBasicBlock("arraydestroy.done"); 1296 1297 if (checkZeroLength) { 1298 llvm::Value *isEmpty = Builder.CreateICmpEQ(begin, end, 1299 "arraydestroy.isempty"); 1300 Builder.CreateCondBr(isEmpty, doneBB, bodyBB); 1301 } 1302 1303 // Enter the loop body, making that address the current address. 1304 llvm::BasicBlock *entryBB = Builder.GetInsertBlock(); 1305 EmitBlock(bodyBB); 1306 llvm::PHINode *elementPast = 1307 Builder.CreatePHI(begin->getType(), 2, "arraydestroy.elementPast"); 1308 elementPast->addIncoming(end, entryBB); 1309 1310 // Shift the address back by one element. 1311 llvm::Value *negativeOne = llvm::ConstantInt::get(SizeTy, -1, true); 1312 llvm::Value *element = Builder.CreateInBoundsGEP(elementPast, negativeOne, 1313 "arraydestroy.element"); 1314 1315 if (useEHCleanup) 1316 pushRegularPartialArrayCleanup(begin, element, type, destroyer); 1317 1318 // Perform the actual destruction there. 1319 destroyer(*this, element, type); 1320 1321 if (useEHCleanup) 1322 PopCleanupBlock(); 1323 1324 // Check whether we've reached the end. 1325 llvm::Value *done = Builder.CreateICmpEQ(element, begin, "arraydestroy.done"); 1326 Builder.CreateCondBr(done, doneBB, bodyBB); 1327 elementPast->addIncoming(element, Builder.GetInsertBlock()); 1328 1329 // Done. 1330 EmitBlock(doneBB); 1331 } 1332 1333 /// Perform partial array destruction as if in an EH cleanup. Unlike 1334 /// emitArrayDestroy, the element type here may still be an array type. 1335 static void emitPartialArrayDestroy(CodeGenFunction &CGF, 1336 llvm::Value *begin, llvm::Value *end, 1337 QualType type, 1338 CodeGenFunction::Destroyer *destroyer) { 1339 // If the element type is itself an array, drill down. 1340 unsigned arrayDepth = 0; 1341 while (const ArrayType *arrayType = CGF.getContext().getAsArrayType(type)) { 1342 // VLAs don't require a GEP index to walk into. 1343 if (!isa<VariableArrayType>(arrayType)) 1344 arrayDepth++; 1345 type = arrayType->getElementType(); 1346 } 1347 1348 if (arrayDepth) { 1349 llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, arrayDepth+1); 1350 1351 SmallVector<llvm::Value*,4> gepIndices(arrayDepth, zero); 1352 begin = CGF.Builder.CreateInBoundsGEP(begin, gepIndices, "pad.arraybegin"); 1353 end = CGF.Builder.CreateInBoundsGEP(end, gepIndices, "pad.arrayend"); 1354 } 1355 1356 // Destroy the array. We don't ever need an EH cleanup because we 1357 // assume that we're in an EH cleanup ourselves, so a throwing 1358 // destructor causes an immediate terminate. 1359 CGF.emitArrayDestroy(begin, end, type, destroyer, 1360 /*checkZeroLength*/ true, /*useEHCleanup*/ false); 1361 } 1362 1363 namespace { 1364 /// RegularPartialArrayDestroy - a cleanup which performs a partial 1365 /// array destroy where the end pointer is regularly determined and 1366 /// does not need to be loaded from a local. 1367 class RegularPartialArrayDestroy : public EHScopeStack::Cleanup { 1368 llvm::Value *ArrayBegin; 1369 llvm::Value *ArrayEnd; 1370 QualType ElementType; 1371 CodeGenFunction::Destroyer *Destroyer; 1372 public: 1373 RegularPartialArrayDestroy(llvm::Value *arrayBegin, llvm::Value *arrayEnd, 1374 QualType elementType, 1375 CodeGenFunction::Destroyer *destroyer) 1376 : ArrayBegin(arrayBegin), ArrayEnd(arrayEnd), 1377 ElementType(elementType), Destroyer(destroyer) {} 1378 1379 void Emit(CodeGenFunction &CGF, Flags flags) { 1380 emitPartialArrayDestroy(CGF, ArrayBegin, ArrayEnd, 1381 ElementType, Destroyer); 1382 } 1383 }; 1384 1385 /// IrregularPartialArrayDestroy - a cleanup which performs a 1386 /// partial array destroy where the end pointer is irregularly 1387 /// determined and must be loaded from a local. 1388 class IrregularPartialArrayDestroy : public EHScopeStack::Cleanup { 1389 llvm::Value *ArrayBegin; 1390 llvm::Value *ArrayEndPointer; 1391 QualType ElementType; 1392 CodeGenFunction::Destroyer *Destroyer; 1393 public: 1394 IrregularPartialArrayDestroy(llvm::Value *arrayBegin, 1395 llvm::Value *arrayEndPointer, 1396 QualType elementType, 1397 CodeGenFunction::Destroyer *destroyer) 1398 : ArrayBegin(arrayBegin), ArrayEndPointer(arrayEndPointer), 1399 ElementType(elementType), Destroyer(destroyer) {} 1400 1401 void Emit(CodeGenFunction &CGF, Flags flags) { 1402 llvm::Value *arrayEnd = CGF.Builder.CreateLoad(ArrayEndPointer); 1403 emitPartialArrayDestroy(CGF, ArrayBegin, arrayEnd, 1404 ElementType, Destroyer); 1405 } 1406 }; 1407 } 1408 1409 /// pushIrregularPartialArrayCleanup - Push an EH cleanup to destroy 1410 /// already-constructed elements of the given array. The cleanup 1411 /// may be popped with DeactivateCleanupBlock or PopCleanupBlock. 1412 /// 1413 /// \param elementType - the immediate element type of the array; 1414 /// possibly still an array type 1415 /// \param array - a value of type elementType* 1416 /// \param destructionKind - the kind of destruction required 1417 /// \param initializedElementCount - a value of type size_t* holding 1418 /// the number of successfully-constructed elements 1419 void CodeGenFunction::pushIrregularPartialArrayCleanup(llvm::Value *arrayBegin, 1420 llvm::Value *arrayEndPointer, 1421 QualType elementType, 1422 Destroyer *destroyer) { 1423 pushFullExprCleanup<IrregularPartialArrayDestroy>(EHCleanup, 1424 arrayBegin, arrayEndPointer, 1425 elementType, destroyer); 1426 } 1427 1428 /// pushRegularPartialArrayCleanup - Push an EH cleanup to destroy 1429 /// already-constructed elements of the given array. The cleanup 1430 /// may be popped with DeactivateCleanupBlock or PopCleanupBlock. 1431 /// 1432 /// \param elementType - the immediate element type of the array; 1433 /// possibly still an array type 1434 /// \param array - a value of type elementType* 1435 /// \param destructionKind - the kind of destruction required 1436 /// \param initializedElementCount - a value of type size_t* holding 1437 /// the number of successfully-constructed elements 1438 void CodeGenFunction::pushRegularPartialArrayCleanup(llvm::Value *arrayBegin, 1439 llvm::Value *arrayEnd, 1440 QualType elementType, 1441 Destroyer *destroyer) { 1442 pushFullExprCleanup<RegularPartialArrayDestroy>(EHCleanup, 1443 arrayBegin, arrayEnd, 1444 elementType, destroyer); 1445 } 1446 1447 namespace { 1448 /// A cleanup to perform a release of an object at the end of a 1449 /// function. This is used to balance out the incoming +1 of a 1450 /// ns_consumed argument when we can't reasonably do that just by 1451 /// not doing the initial retain for a __block argument. 1452 struct ConsumeARCParameter : EHScopeStack::Cleanup { 1453 ConsumeARCParameter(llvm::Value *param) : Param(param) {} 1454 1455 llvm::Value *Param; 1456 1457 void Emit(CodeGenFunction &CGF, Flags flags) { 1458 CGF.EmitARCRelease(Param, /*precise*/ false); 1459 } 1460 }; 1461 } 1462 1463 /// Emit an alloca (or GlobalValue depending on target) 1464 /// for the specified parameter and set up LocalDeclMap. 1465 void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg, 1466 unsigned ArgNo) { 1467 // FIXME: Why isn't ImplicitParamDecl a ParmVarDecl? 1468 assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) && 1469 "Invalid argument to EmitParmDecl"); 1470 1471 Arg->setName(D.getName()); 1472 1473 // Use better IR generation for certain implicit parameters. 1474 if (isa<ImplicitParamDecl>(D)) { 1475 // The only implicit argument a block has is its literal. 1476 if (BlockInfo) { 1477 LocalDeclMap[&D] = Arg; 1478 1479 if (CGDebugInfo *DI = getDebugInfo()) { 1480 DI->setLocation(D.getLocation()); 1481 DI->EmitDeclareOfBlockLiteralArgVariable(*BlockInfo, Arg, Builder); 1482 } 1483 1484 return; 1485 } 1486 } 1487 1488 QualType Ty = D.getType(); 1489 1490 llvm::Value *DeclPtr; 1491 // If this is an aggregate or variable sized value, reuse the input pointer. 1492 if (!Ty->isConstantSizeType() || 1493 CodeGenFunction::hasAggregateLLVMType(Ty)) { 1494 DeclPtr = Arg; 1495 } else { 1496 // Otherwise, create a temporary to hold the value. 1497 llvm::AllocaInst *Alloc = CreateTempAlloca(ConvertTypeForMem(Ty), 1498 D.getName() + ".addr"); 1499 Alloc->setAlignment(getContext().getDeclAlign(&D).getQuantity()); 1500 DeclPtr = Alloc; 1501 1502 bool doStore = true; 1503 1504 Qualifiers qs = Ty.getQualifiers(); 1505 1506 if (Qualifiers::ObjCLifetime lt = qs.getObjCLifetime()) { 1507 // We honor __attribute__((ns_consumed)) for types with lifetime. 1508 // For __strong, it's handled by just skipping the initial retain; 1509 // otherwise we have to balance out the initial +1 with an extra 1510 // cleanup to do the release at the end of the function. 1511 bool isConsumed = D.hasAttr<NSConsumedAttr>(); 1512 1513 // 'self' is always formally __strong, but if this is not an 1514 // init method then we don't want to retain it. 1515 if (D.isARCPseudoStrong()) { 1516 const ObjCMethodDecl *method = cast<ObjCMethodDecl>(CurCodeDecl); 1517 assert(&D == method->getSelfDecl()); 1518 assert(lt == Qualifiers::OCL_Strong); 1519 assert(qs.hasConst()); 1520 assert(method->getMethodFamily() != OMF_init); 1521 (void) method; 1522 lt = Qualifiers::OCL_ExplicitNone; 1523 } 1524 1525 if (lt == Qualifiers::OCL_Strong) { 1526 if (!isConsumed) 1527 // Don't use objc_retainBlock for block pointers, because we 1528 // don't want to Block_copy something just because we got it 1529 // as a parameter. 1530 Arg = EmitARCRetainNonBlock(Arg); 1531 } else { 1532 // Push the cleanup for a consumed parameter. 1533 if (isConsumed) 1534 EHStack.pushCleanup<ConsumeARCParameter>(getARCCleanupKind(), Arg); 1535 1536 if (lt == Qualifiers::OCL_Weak) { 1537 EmitARCInitWeak(DeclPtr, Arg); 1538 doStore = false; // The weak init is a store, no need to do two. 1539 } 1540 } 1541 1542 // Enter the cleanup scope. 1543 EmitAutoVarWithLifetime(*this, D, DeclPtr, lt); 1544 } 1545 1546 // Store the initial value into the alloca. 1547 if (doStore) { 1548 LValue lv = MakeAddrLValue(DeclPtr, Ty, 1549 getContext().getDeclAlign(&D)); 1550 EmitStoreOfScalar(Arg, lv, /* isInitialization */ true); 1551 } 1552 } 1553 1554 llvm::Value *&DMEntry = LocalDeclMap[&D]; 1555 assert(DMEntry == 0 && "Decl already exists in localdeclmap!"); 1556 DMEntry = DeclPtr; 1557 1558 // Emit debug info for param declaration. 1559 if (CGDebugInfo *DI = getDebugInfo()) 1560 DI->EmitDeclareOfArgVariable(&D, DeclPtr, ArgNo, Builder); 1561 1562 if (D.hasAttr<AnnotateAttr>()) 1563 EmitVarAnnotations(&D, DeclPtr); 1564 } 1565