CGDecl.cpp revision 251662
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 "CGDebugInfo.h" 16#include "CGOpenCLRuntime.h" 17#include "CodeGenModule.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/IR/DataLayout.h" 26#include "llvm/IR/GlobalVariable.h" 27#include "llvm/IR/Intrinsics.h" 28#include "llvm/IR/Type.h" 29using namespace clang; 30using namespace CodeGen; 31 32 33void 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::MSProperty: 49 case Decl::IndirectField: 50 case Decl::ObjCIvar: 51 case Decl::ObjCAtDefsField: 52 case Decl::ParmVar: 53 case Decl::ImplicitParam: 54 case Decl::ClassTemplate: 55 case Decl::FunctionTemplate: 56 case Decl::TypeAliasTemplate: 57 case Decl::TemplateTemplateParm: 58 case Decl::ObjCMethod: 59 case Decl::ObjCCategory: 60 case Decl::ObjCProtocol: 61 case Decl::ObjCInterface: 62 case Decl::ObjCCategoryImpl: 63 case Decl::ObjCImplementation: 64 case Decl::ObjCProperty: 65 case Decl::ObjCCompatibleAlias: 66 case Decl::AccessSpec: 67 case Decl::LinkageSpec: 68 case Decl::ObjCPropertyImpl: 69 case Decl::FileScopeAsm: 70 case Decl::Friend: 71 case Decl::FriendTemplate: 72 case Decl::Block: 73 case Decl::Captured: 74 case Decl::ClassScopeFunctionSpecialization: 75 llvm_unreachable("Declaration should not be in declstmts!"); 76 case Decl::Function: // void X(); 77 case Decl::Record: // struct/union/class X; 78 case Decl::Enum: // enum X; 79 case Decl::EnumConstant: // enum ? { X = ? } 80 case Decl::CXXRecord: // struct/union/class X; [C++] 81 case Decl::Using: // using X; [C++] 82 case Decl::UsingShadow: 83 case Decl::NamespaceAlias: 84 case Decl::StaticAssert: // static_assert(X, ""); [C++0x] 85 case Decl::Label: // __label__ x; 86 case Decl::Import: 87 case Decl::OMPThreadPrivate: 88 case Decl::Empty: 89 // None of these decls require codegen support. 90 return; 91 92 case Decl::UsingDirective: // using namespace X; [C++] 93 if (CGDebugInfo *DI = getDebugInfo()) 94 DI->EmitUsingDirective(cast<UsingDirectiveDecl>(D)); 95 return; 96 case Decl::Var: { 97 const VarDecl &VD = cast<VarDecl>(D); 98 assert(VD.isLocalVarDecl() && 99 "Should not see file-scope variables inside a function!"); 100 return EmitVarDecl(VD); 101 } 102 103 case Decl::Typedef: // typedef int X; 104 case Decl::TypeAlias: { // using X = int; [C++0x] 105 const TypedefNameDecl &TD = cast<TypedefNameDecl>(D); 106 QualType Ty = TD.getUnderlyingType(); 107 108 if (Ty->isVariablyModifiedType()) 109 EmitVariablyModifiedType(Ty); 110 } 111 } 112} 113 114/// EmitVarDecl - This method handles emission of any variable declaration 115/// inside a function, including static vars etc. 116void CodeGenFunction::EmitVarDecl(const VarDecl &D) { 117 switch (D.getStorageClass()) { 118 case SC_None: 119 case SC_Auto: 120 case SC_Register: 121 return EmitAutoVarDecl(D); 122 case SC_Static: { 123 llvm::GlobalValue::LinkageTypes Linkage = 124 llvm::GlobalValue::InternalLinkage; 125 126 // If the function definition has some sort of weak linkage, its 127 // static variables should also be weak so that they get properly 128 // uniqued. We can't do this in C, though, because there's no 129 // standard way to agree on which variables are the same (i.e. 130 // there's no mangling). 131 if (getLangOpts().CPlusPlus) 132 if (llvm::GlobalValue::isWeakForLinker(CurFn->getLinkage())) 133 Linkage = CurFn->getLinkage(); 134 135 return EmitStaticVarDecl(D, Linkage); 136 } 137 case SC_Extern: 138 case SC_PrivateExtern: 139 // Don't emit it now, allow it to be emitted lazily on its first use. 140 return; 141 case SC_OpenCLWorkGroupLocal: 142 return CGM.getOpenCLRuntime().EmitWorkGroupLocalVarDecl(*this, D); 143 } 144 145 llvm_unreachable("Unknown storage class"); 146} 147 148static std::string GetStaticDeclName(CodeGenFunction &CGF, const VarDecl &D, 149 const char *Separator) { 150 CodeGenModule &CGM = CGF.CGM; 151 if (CGF.getLangOpts().CPlusPlus) { 152 StringRef Name = CGM.getMangledName(&D); 153 return Name.str(); 154 } 155 156 std::string ContextName; 157 if (!CGF.CurFuncDecl) { 158 // Better be in a block declared in global scope. 159 const NamedDecl *ND = cast<NamedDecl>(&D); 160 const DeclContext *DC = ND->getDeclContext(); 161 if (const BlockDecl *BD = dyn_cast<BlockDecl>(DC)) { 162 MangleBuffer Name; 163 CGM.getBlockMangledName(GlobalDecl(), Name, BD); 164 ContextName = Name.getString(); 165 } 166 else 167 llvm_unreachable("Unknown context for block static var decl"); 168 } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CGF.CurFuncDecl)) { 169 StringRef Name = CGM.getMangledName(FD); 170 ContextName = Name.str(); 171 } else if (isa<ObjCMethodDecl>(CGF.CurFuncDecl)) 172 ContextName = CGF.CurFn->getName(); 173 else 174 llvm_unreachable("Unknown context for static var decl"); 175 176 return ContextName + Separator + D.getNameAsString(); 177} 178 179llvm::GlobalVariable * 180CodeGenFunction::CreateStaticVarDecl(const VarDecl &D, 181 const char *Separator, 182 llvm::GlobalValue::LinkageTypes Linkage) { 183 QualType Ty = D.getType(); 184 assert(Ty->isConstantSizeType() && "VLAs can't be static"); 185 186 // Use the label if the variable is renamed with the asm-label extension. 187 std::string Name; 188 if (D.hasAttr<AsmLabelAttr>()) 189 Name = CGM.getMangledName(&D); 190 else 191 Name = GetStaticDeclName(*this, D, Separator); 192 193 llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(Ty); 194 unsigned AddrSpace = 195 CGM.GetGlobalVarAddressSpace(&D, CGM.getContext().getTargetAddressSpace(Ty)); 196 llvm::GlobalVariable *GV = 197 new llvm::GlobalVariable(CGM.getModule(), LTy, 198 Ty.isConstant(getContext()), Linkage, 199 CGM.EmitNullConstant(D.getType()), Name, 0, 200 llvm::GlobalVariable::NotThreadLocal, 201 AddrSpace); 202 GV->setAlignment(getContext().getDeclAlign(&D).getQuantity()); 203 if (Linkage != llvm::GlobalValue::InternalLinkage) 204 GV->setVisibility(CurFn->getVisibility()); 205 206 if (D.getTLSKind()) 207 CGM.setTLSMode(GV, D); 208 209 return GV; 210} 211 212/// hasNontrivialDestruction - Determine whether a type's destruction is 213/// non-trivial. If so, and the variable uses static initialization, we must 214/// register its destructor to run on exit. 215static bool hasNontrivialDestruction(QualType T) { 216 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl(); 217 return RD && !RD->hasTrivialDestructor(); 218} 219 220/// AddInitializerToStaticVarDecl - Add the initializer for 'D' to the 221/// global variable that has already been created for it. If the initializer 222/// has a different type than GV does, this may free GV and return a different 223/// one. Otherwise it just returns GV. 224llvm::GlobalVariable * 225CodeGenFunction::AddInitializerToStaticVarDecl(const VarDecl &D, 226 llvm::GlobalVariable *GV) { 227 llvm::Constant *Init = CGM.EmitConstantInit(D, this); 228 229 // If constant emission failed, then this should be a C++ static 230 // initializer. 231 if (!Init) { 232 if (!getLangOpts().CPlusPlus) 233 CGM.ErrorUnsupported(D.getInit(), "constant l-value expression"); 234 else if (Builder.GetInsertBlock()) { 235 // Since we have a static initializer, this global variable can't 236 // be constant. 237 GV->setConstant(false); 238 239 EmitCXXGuardedInit(D, GV, /*PerformInit*/true); 240 } 241 return GV; 242 } 243 244 // The initializer may differ in type from the global. Rewrite 245 // the global to match the initializer. (We have to do this 246 // because some types, like unions, can't be completely represented 247 // in the LLVM type system.) 248 if (GV->getType()->getElementType() != Init->getType()) { 249 llvm::GlobalVariable *OldGV = GV; 250 251 GV = new llvm::GlobalVariable(CGM.getModule(), Init->getType(), 252 OldGV->isConstant(), 253 OldGV->getLinkage(), Init, "", 254 /*InsertBefore*/ OldGV, 255 OldGV->getThreadLocalMode(), 256 CGM.getContext().getTargetAddressSpace(D.getType())); 257 GV->setVisibility(OldGV->getVisibility()); 258 259 // Steal the name of the old global 260 GV->takeName(OldGV); 261 262 // Replace all uses of the old global with the new global 263 llvm::Constant *NewPtrForOldDecl = 264 llvm::ConstantExpr::getBitCast(GV, OldGV->getType()); 265 OldGV->replaceAllUsesWith(NewPtrForOldDecl); 266 267 // Erase the old global, since it is no longer used. 268 OldGV->eraseFromParent(); 269 } 270 271 GV->setConstant(CGM.isTypeConstant(D.getType(), true)); 272 GV->setInitializer(Init); 273 274 if (hasNontrivialDestruction(D.getType())) { 275 // We have a constant initializer, but a nontrivial destructor. We still 276 // need to perform a guarded "initialization" in order to register the 277 // destructor. 278 EmitCXXGuardedInit(D, GV, /*PerformInit*/false); 279 } 280 281 return GV; 282} 283 284void CodeGenFunction::EmitStaticVarDecl(const VarDecl &D, 285 llvm::GlobalValue::LinkageTypes Linkage) { 286 llvm::Value *&DMEntry = LocalDeclMap[&D]; 287 assert(DMEntry == 0 && "Decl already exists in localdeclmap!"); 288 289 // Check to see if we already have a global variable for this 290 // declaration. This can happen when double-emitting function 291 // bodies, e.g. with complete and base constructors. 292 llvm::Constant *addr = 293 CGM.getStaticLocalDeclAddress(&D); 294 295 llvm::GlobalVariable *var; 296 if (addr) { 297 var = cast<llvm::GlobalVariable>(addr->stripPointerCasts()); 298 } else { 299 addr = var = CreateStaticVarDecl(D, ".", Linkage); 300 } 301 302 // Store into LocalDeclMap before generating initializer to handle 303 // circular references. 304 DMEntry = addr; 305 CGM.setStaticLocalDeclAddress(&D, addr); 306 307 // We can't have a VLA here, but we can have a pointer to a VLA, 308 // even though that doesn't really make any sense. 309 // Make sure to evaluate VLA bounds now so that we have them for later. 310 if (D.getType()->isVariablyModifiedType()) 311 EmitVariablyModifiedType(D.getType()); 312 313 // Save the type in case adding the initializer forces a type change. 314 llvm::Type *expectedType = addr->getType(); 315 316 // If this value has an initializer, emit it. 317 if (D.getInit()) 318 var = AddInitializerToStaticVarDecl(D, var); 319 320 var->setAlignment(getContext().getDeclAlign(&D).getQuantity()); 321 322 if (D.hasAttr<AnnotateAttr>()) 323 CGM.AddGlobalAnnotations(&D, var); 324 325 if (const SectionAttr *SA = D.getAttr<SectionAttr>()) 326 var->setSection(SA->getName()); 327 328 if (D.hasAttr<UsedAttr>()) 329 CGM.AddUsedGlobal(var); 330 331 // We may have to cast the constant because of the initializer 332 // mismatch above. 333 // 334 // FIXME: It is really dangerous to store this in the map; if anyone 335 // RAUW's the GV uses of this constant will be invalid. 336 llvm::Constant *castedAddr = llvm::ConstantExpr::getBitCast(var, expectedType); 337 DMEntry = castedAddr; 338 CGM.setStaticLocalDeclAddress(&D, castedAddr); 339 340 // Emit global variable debug descriptor for static vars. 341 CGDebugInfo *DI = getDebugInfo(); 342 if (DI && 343 CGM.getCodeGenOpts().getDebugInfo() >= CodeGenOptions::LimitedDebugInfo) { 344 DI->setLocation(D.getLocation()); 345 DI->EmitGlobalVariable(var, &D); 346 } 347} 348 349namespace { 350 struct DestroyObject : EHScopeStack::Cleanup { 351 DestroyObject(llvm::Value *addr, QualType type, 352 CodeGenFunction::Destroyer *destroyer, 353 bool useEHCleanupForArray) 354 : addr(addr), type(type), destroyer(destroyer), 355 useEHCleanupForArray(useEHCleanupForArray) {} 356 357 llvm::Value *addr; 358 QualType type; 359 CodeGenFunction::Destroyer *destroyer; 360 bool useEHCleanupForArray; 361 362 void Emit(CodeGenFunction &CGF, Flags flags) { 363 // Don't use an EH cleanup recursively from an EH cleanup. 364 bool useEHCleanupForArray = 365 flags.isForNormalCleanup() && this->useEHCleanupForArray; 366 367 CGF.emitDestroy(addr, type, destroyer, useEHCleanupForArray); 368 } 369 }; 370 371 struct DestroyNRVOVariable : EHScopeStack::Cleanup { 372 DestroyNRVOVariable(llvm::Value *addr, 373 const CXXDestructorDecl *Dtor, 374 llvm::Value *NRVOFlag) 375 : Dtor(Dtor), NRVOFlag(NRVOFlag), Loc(addr) {} 376 377 const CXXDestructorDecl *Dtor; 378 llvm::Value *NRVOFlag; 379 llvm::Value *Loc; 380 381 void Emit(CodeGenFunction &CGF, Flags flags) { 382 // Along the exceptions path we always execute the dtor. 383 bool NRVO = flags.isForNormalCleanup() && NRVOFlag; 384 385 llvm::BasicBlock *SkipDtorBB = 0; 386 if (NRVO) { 387 // If we exited via NRVO, we skip the destructor call. 388 llvm::BasicBlock *RunDtorBB = CGF.createBasicBlock("nrvo.unused"); 389 SkipDtorBB = CGF.createBasicBlock("nrvo.skipdtor"); 390 llvm::Value *DidNRVO = CGF.Builder.CreateLoad(NRVOFlag, "nrvo.val"); 391 CGF.Builder.CreateCondBr(DidNRVO, SkipDtorBB, RunDtorBB); 392 CGF.EmitBlock(RunDtorBB); 393 } 394 395 CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete, 396 /*ForVirtualBase=*/false, 397 /*Delegating=*/false, 398 Loc); 399 400 if (NRVO) CGF.EmitBlock(SkipDtorBB); 401 } 402 }; 403 404 struct CallStackRestore : EHScopeStack::Cleanup { 405 llvm::Value *Stack; 406 CallStackRestore(llvm::Value *Stack) : Stack(Stack) {} 407 void Emit(CodeGenFunction &CGF, Flags flags) { 408 llvm::Value *V = CGF.Builder.CreateLoad(Stack); 409 llvm::Value *F = CGF.CGM.getIntrinsic(llvm::Intrinsic::stackrestore); 410 CGF.Builder.CreateCall(F, V); 411 } 412 }; 413 414 struct ExtendGCLifetime : EHScopeStack::Cleanup { 415 const VarDecl &Var; 416 ExtendGCLifetime(const VarDecl *var) : Var(*var) {} 417 418 void Emit(CodeGenFunction &CGF, Flags flags) { 419 // Compute the address of the local variable, in case it's a 420 // byref or something. 421 DeclRefExpr DRE(const_cast<VarDecl*>(&Var), false, 422 Var.getType(), VK_LValue, SourceLocation()); 423 llvm::Value *value = CGF.EmitLoadOfScalar(CGF.EmitDeclRefLValue(&DRE)); 424 CGF.EmitExtendGCLifetime(value); 425 } 426 }; 427 428 struct CallCleanupFunction : EHScopeStack::Cleanup { 429 llvm::Constant *CleanupFn; 430 const CGFunctionInfo &FnInfo; 431 const VarDecl &Var; 432 433 CallCleanupFunction(llvm::Constant *CleanupFn, const CGFunctionInfo *Info, 434 const VarDecl *Var) 435 : CleanupFn(CleanupFn), FnInfo(*Info), Var(*Var) {} 436 437 void Emit(CodeGenFunction &CGF, Flags flags) { 438 DeclRefExpr DRE(const_cast<VarDecl*>(&Var), false, 439 Var.getType(), VK_LValue, SourceLocation()); 440 // Compute the address of the local variable, in case it's a byref 441 // or something. 442 llvm::Value *Addr = CGF.EmitDeclRefLValue(&DRE).getAddress(); 443 444 // In some cases, the type of the function argument will be different from 445 // the type of the pointer. An example of this is 446 // void f(void* arg); 447 // __attribute__((cleanup(f))) void *g; 448 // 449 // To fix this we insert a bitcast here. 450 QualType ArgTy = FnInfo.arg_begin()->type; 451 llvm::Value *Arg = 452 CGF.Builder.CreateBitCast(Addr, CGF.ConvertType(ArgTy)); 453 454 CallArgList Args; 455 Args.add(RValue::get(Arg), 456 CGF.getContext().getPointerType(Var.getType())); 457 CGF.EmitCall(FnInfo, CleanupFn, ReturnValueSlot(), Args); 458 } 459 }; 460 461 /// A cleanup to call @llvm.lifetime.end. 462 class CallLifetimeEnd : public EHScopeStack::Cleanup { 463 llvm::Value *Addr; 464 llvm::Value *Size; 465 public: 466 CallLifetimeEnd(llvm::Value *addr, llvm::Value *size) 467 : Addr(addr), Size(size) {} 468 469 void Emit(CodeGenFunction &CGF, Flags flags) { 470 llvm::Value *castAddr = CGF.Builder.CreateBitCast(Addr, CGF.Int8PtrTy); 471 CGF.Builder.CreateCall2(CGF.CGM.getLLVMLifetimeEndFn(), 472 Size, castAddr) 473 ->setDoesNotThrow(); 474 } 475 }; 476} 477 478/// EmitAutoVarWithLifetime - Does the setup required for an automatic 479/// variable with lifetime. 480static void EmitAutoVarWithLifetime(CodeGenFunction &CGF, const VarDecl &var, 481 llvm::Value *addr, 482 Qualifiers::ObjCLifetime lifetime) { 483 switch (lifetime) { 484 case Qualifiers::OCL_None: 485 llvm_unreachable("present but none"); 486 487 case Qualifiers::OCL_ExplicitNone: 488 // nothing to do 489 break; 490 491 case Qualifiers::OCL_Strong: { 492 CodeGenFunction::Destroyer *destroyer = 493 (var.hasAttr<ObjCPreciseLifetimeAttr>() 494 ? CodeGenFunction::destroyARCStrongPrecise 495 : CodeGenFunction::destroyARCStrongImprecise); 496 497 CleanupKind cleanupKind = CGF.getARCCleanupKind(); 498 CGF.pushDestroy(cleanupKind, addr, var.getType(), destroyer, 499 cleanupKind & EHCleanup); 500 break; 501 } 502 case Qualifiers::OCL_Autoreleasing: 503 // nothing to do 504 break; 505 506 case Qualifiers::OCL_Weak: 507 // __weak objects always get EH cleanups; otherwise, exceptions 508 // could cause really nasty crashes instead of mere leaks. 509 CGF.pushDestroy(NormalAndEHCleanup, addr, var.getType(), 510 CodeGenFunction::destroyARCWeak, 511 /*useEHCleanup*/ true); 512 break; 513 } 514} 515 516static bool isAccessedBy(const VarDecl &var, const Stmt *s) { 517 if (const Expr *e = dyn_cast<Expr>(s)) { 518 // Skip the most common kinds of expressions that make 519 // hierarchy-walking expensive. 520 s = e = e->IgnoreParenCasts(); 521 522 if (const DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e)) 523 return (ref->getDecl() == &var); 524 if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) { 525 const BlockDecl *block = be->getBlockDecl(); 526 for (BlockDecl::capture_const_iterator i = block->capture_begin(), 527 e = block->capture_end(); i != e; ++i) { 528 if (i->getVariable() == &var) 529 return true; 530 } 531 } 532 } 533 534 for (Stmt::const_child_range children = s->children(); children; ++children) 535 // children might be null; as in missing decl or conditional of an if-stmt. 536 if ((*children) && isAccessedBy(var, *children)) 537 return true; 538 539 return false; 540} 541 542static bool isAccessedBy(const ValueDecl *decl, const Expr *e) { 543 if (!decl) return false; 544 if (!isa<VarDecl>(decl)) return false; 545 const VarDecl *var = cast<VarDecl>(decl); 546 return isAccessedBy(*var, e); 547} 548 549static void drillIntoBlockVariable(CodeGenFunction &CGF, 550 LValue &lvalue, 551 const VarDecl *var) { 552 lvalue.setAddress(CGF.BuildBlockByrefAddress(lvalue.getAddress(), var)); 553} 554 555void CodeGenFunction::EmitScalarInit(const Expr *init, 556 const ValueDecl *D, 557 LValue lvalue, 558 bool capturedByInit) { 559 Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime(); 560 if (!lifetime) { 561 llvm::Value *value = EmitScalarExpr(init); 562 if (capturedByInit) 563 drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 564 EmitStoreThroughLValue(RValue::get(value), lvalue, true); 565 return; 566 } 567 568 // If we're emitting a value with lifetime, we have to do the 569 // initialization *before* we leave the cleanup scopes. 570 if (const ExprWithCleanups *ewc = dyn_cast<ExprWithCleanups>(init)) { 571 enterFullExpression(ewc); 572 init = ewc->getSubExpr(); 573 } 574 CodeGenFunction::RunCleanupsScope Scope(*this); 575 576 // We have to maintain the illusion that the variable is 577 // zero-initialized. If the variable might be accessed in its 578 // initializer, zero-initialize before running the initializer, then 579 // actually perform the initialization with an assign. 580 bool accessedByInit = false; 581 if (lifetime != Qualifiers::OCL_ExplicitNone) 582 accessedByInit = (capturedByInit || isAccessedBy(D, init)); 583 if (accessedByInit) { 584 LValue tempLV = lvalue; 585 // Drill down to the __block object if necessary. 586 if (capturedByInit) { 587 // We can use a simple GEP for this because it can't have been 588 // moved yet. 589 tempLV.setAddress(Builder.CreateStructGEP(tempLV.getAddress(), 590 getByRefValueLLVMField(cast<VarDecl>(D)))); 591 } 592 593 llvm::PointerType *ty 594 = cast<llvm::PointerType>(tempLV.getAddress()->getType()); 595 ty = cast<llvm::PointerType>(ty->getElementType()); 596 597 llvm::Value *zero = llvm::ConstantPointerNull::get(ty); 598 599 // If __weak, we want to use a barrier under certain conditions. 600 if (lifetime == Qualifiers::OCL_Weak) 601 EmitARCInitWeak(tempLV.getAddress(), zero); 602 603 // Otherwise just do a simple store. 604 else 605 EmitStoreOfScalar(zero, tempLV, /* isInitialization */ true); 606 } 607 608 // Emit the initializer. 609 llvm::Value *value = 0; 610 611 switch (lifetime) { 612 case Qualifiers::OCL_None: 613 llvm_unreachable("present but none"); 614 615 case Qualifiers::OCL_ExplicitNone: 616 // nothing to do 617 value = EmitScalarExpr(init); 618 break; 619 620 case Qualifiers::OCL_Strong: { 621 value = EmitARCRetainScalarExpr(init); 622 break; 623 } 624 625 case Qualifiers::OCL_Weak: { 626 // No way to optimize a producing initializer into this. It's not 627 // worth optimizing for, because the value will immediately 628 // disappear in the common case. 629 value = EmitScalarExpr(init); 630 631 if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 632 if (accessedByInit) 633 EmitARCStoreWeak(lvalue.getAddress(), value, /*ignored*/ true); 634 else 635 EmitARCInitWeak(lvalue.getAddress(), value); 636 return; 637 } 638 639 case Qualifiers::OCL_Autoreleasing: 640 value = EmitARCRetainAutoreleaseScalarExpr(init); 641 break; 642 } 643 644 if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 645 646 // If the variable might have been accessed by its initializer, we 647 // might have to initialize with a barrier. We have to do this for 648 // both __weak and __strong, but __weak got filtered out above. 649 if (accessedByInit && lifetime == Qualifiers::OCL_Strong) { 650 llvm::Value *oldValue = EmitLoadOfScalar(lvalue); 651 EmitStoreOfScalar(value, lvalue, /* isInitialization */ true); 652 EmitARCRelease(oldValue, ARCImpreciseLifetime); 653 return; 654 } 655 656 EmitStoreOfScalar(value, lvalue, /* isInitialization */ true); 657} 658 659/// EmitScalarInit - Initialize the given lvalue with the given object. 660void CodeGenFunction::EmitScalarInit(llvm::Value *init, LValue lvalue) { 661 Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime(); 662 if (!lifetime) 663 return EmitStoreThroughLValue(RValue::get(init), lvalue, true); 664 665 switch (lifetime) { 666 case Qualifiers::OCL_None: 667 llvm_unreachable("present but none"); 668 669 case Qualifiers::OCL_ExplicitNone: 670 // nothing to do 671 break; 672 673 case Qualifiers::OCL_Strong: 674 init = EmitARCRetain(lvalue.getType(), init); 675 break; 676 677 case Qualifiers::OCL_Weak: 678 // Initialize and then skip the primitive store. 679 EmitARCInitWeak(lvalue.getAddress(), init); 680 return; 681 682 case Qualifiers::OCL_Autoreleasing: 683 init = EmitARCRetainAutorelease(lvalue.getType(), init); 684 break; 685 } 686 687 EmitStoreOfScalar(init, lvalue, /* isInitialization */ true); 688} 689 690/// canEmitInitWithFewStoresAfterMemset - Decide whether we can emit the 691/// non-zero parts of the specified initializer with equal or fewer than 692/// NumStores scalar stores. 693static bool canEmitInitWithFewStoresAfterMemset(llvm::Constant *Init, 694 unsigned &NumStores) { 695 // Zero and Undef never requires any extra stores. 696 if (isa<llvm::ConstantAggregateZero>(Init) || 697 isa<llvm::ConstantPointerNull>(Init) || 698 isa<llvm::UndefValue>(Init)) 699 return true; 700 if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) || 701 isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) || 702 isa<llvm::ConstantExpr>(Init)) 703 return Init->isNullValue() || NumStores--; 704 705 // See if we can emit each element. 706 if (isa<llvm::ConstantArray>(Init) || isa<llvm::ConstantStruct>(Init)) { 707 for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) { 708 llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i)); 709 if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores)) 710 return false; 711 } 712 return true; 713 } 714 715 if (llvm::ConstantDataSequential *CDS = 716 dyn_cast<llvm::ConstantDataSequential>(Init)) { 717 for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) { 718 llvm::Constant *Elt = CDS->getElementAsConstant(i); 719 if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores)) 720 return false; 721 } 722 return true; 723 } 724 725 // Anything else is hard and scary. 726 return false; 727} 728 729/// emitStoresForInitAfterMemset - For inits that 730/// canEmitInitWithFewStoresAfterMemset returned true for, emit the scalar 731/// stores that would be required. 732static void emitStoresForInitAfterMemset(llvm::Constant *Init, llvm::Value *Loc, 733 bool isVolatile, CGBuilderTy &Builder) { 734 assert(!Init->isNullValue() && !isa<llvm::UndefValue>(Init) && 735 "called emitStoresForInitAfterMemset for zero or undef value."); 736 737 if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) || 738 isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) || 739 isa<llvm::ConstantExpr>(Init)) { 740 Builder.CreateStore(Init, Loc, isVolatile); 741 return; 742 } 743 744 if (llvm::ConstantDataSequential *CDS = 745 dyn_cast<llvm::ConstantDataSequential>(Init)) { 746 for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) { 747 llvm::Constant *Elt = CDS->getElementAsConstant(i); 748 749 // If necessary, get a pointer to the element and emit it. 750 if (!Elt->isNullValue() && !isa<llvm::UndefValue>(Elt)) 751 emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i), 752 isVolatile, Builder); 753 } 754 return; 755 } 756 757 assert((isa<llvm::ConstantStruct>(Init) || isa<llvm::ConstantArray>(Init)) && 758 "Unknown value type!"); 759 760 for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) { 761 llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i)); 762 763 // If necessary, get a pointer to the element and emit it. 764 if (!Elt->isNullValue() && !isa<llvm::UndefValue>(Elt)) 765 emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i), 766 isVolatile, Builder); 767 } 768} 769 770 771/// shouldUseMemSetPlusStoresToInitialize - Decide whether we should use memset 772/// plus some stores to initialize a local variable instead of using a memcpy 773/// from a constant global. It is beneficial to use memset if the global is all 774/// zeros, or mostly zeros and large. 775static bool shouldUseMemSetPlusStoresToInitialize(llvm::Constant *Init, 776 uint64_t GlobalSize) { 777 // If a global is all zeros, always use a memset. 778 if (isa<llvm::ConstantAggregateZero>(Init)) return true; 779 780 // If a non-zero global is <= 32 bytes, always use a memcpy. If it is large, 781 // do it if it will require 6 or fewer scalar stores. 782 // TODO: Should budget depends on the size? Avoiding a large global warrants 783 // plopping in more stores. 784 unsigned StoreBudget = 6; 785 uint64_t SizeLimit = 32; 786 787 return GlobalSize > SizeLimit && 788 canEmitInitWithFewStoresAfterMemset(Init, StoreBudget); 789} 790 791/// Should we use the LLVM lifetime intrinsics for the given local variable? 792static bool shouldUseLifetimeMarkers(CodeGenFunction &CGF, const VarDecl &D, 793 unsigned Size) { 794 // Always emit lifetime markers in -fsanitize=use-after-scope mode. 795 if (CGF.getLangOpts().Sanitize.UseAfterScope) 796 return true; 797 // For now, only in optimized builds. 798 if (CGF.CGM.getCodeGenOpts().OptimizationLevel == 0) 799 return false; 800 801 // Limit the size of marked objects to 32 bytes. We don't want to increase 802 // compile time by marking tiny objects. 803 unsigned SizeThreshold = 32; 804 805 return Size > SizeThreshold; 806} 807 808 809/// EmitAutoVarDecl - Emit code and set up an entry in LocalDeclMap for a 810/// variable declaration with auto, register, or no storage class specifier. 811/// These turn into simple stack objects, or GlobalValues depending on target. 812void CodeGenFunction::EmitAutoVarDecl(const VarDecl &D) { 813 AutoVarEmission emission = EmitAutoVarAlloca(D); 814 EmitAutoVarInit(emission); 815 EmitAutoVarCleanups(emission); 816} 817 818/// EmitAutoVarAlloca - Emit the alloca and debug information for a 819/// local variable. Does not emit initalization or destruction. 820CodeGenFunction::AutoVarEmission 821CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) { 822 QualType Ty = D.getType(); 823 824 AutoVarEmission emission(D); 825 826 bool isByRef = D.hasAttr<BlocksAttr>(); 827 emission.IsByRef = isByRef; 828 829 CharUnits alignment = getContext().getDeclAlign(&D); 830 emission.Alignment = alignment; 831 832 // If the type is variably-modified, emit all the VLA sizes for it. 833 if (Ty->isVariablyModifiedType()) 834 EmitVariablyModifiedType(Ty); 835 836 llvm::Value *DeclPtr; 837 if (Ty->isConstantSizeType()) { 838 bool NRVO = getLangOpts().ElideConstructors && 839 D.isNRVOVariable(); 840 841 // If this value is a POD array or struct with a statically 842 // determinable constant initializer, there are optimizations we can do. 843 // 844 // TODO: We should constant-evaluate the initializer of any variable, 845 // as long as it is initialized by a constant expression. Currently, 846 // isConstantInitializer produces wrong answers for structs with 847 // reference or bitfield members, and a few other cases, and checking 848 // for POD-ness protects us from some of these. 849 if (D.getInit() && 850 (Ty->isArrayType() || Ty->isRecordType()) && 851 (Ty.isPODType(getContext()) || 852 getContext().getBaseElementType(Ty)->isObjCObjectPointerType()) && 853 D.getInit()->isConstantInitializer(getContext(), false)) { 854 855 // If the variable's a const type, and it's neither an NRVO 856 // candidate nor a __block variable and has no mutable members, 857 // emit it as a global instead. 858 if (CGM.getCodeGenOpts().MergeAllConstants && !NRVO && !isByRef && 859 CGM.isTypeConstant(Ty, true)) { 860 EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage); 861 862 emission.Address = 0; // signal this condition to later callbacks 863 assert(emission.wasEmittedAsGlobal()); 864 return emission; 865 } 866 867 // Otherwise, tell the initialization code that we're in this case. 868 emission.IsConstantAggregate = true; 869 } 870 871 // A normal fixed sized variable becomes an alloca in the entry block, 872 // unless it's an NRVO variable. 873 llvm::Type *LTy = ConvertTypeForMem(Ty); 874 875 if (NRVO) { 876 // The named return value optimization: allocate this variable in the 877 // return slot, so that we can elide the copy when returning this 878 // variable (C++0x [class.copy]p34). 879 DeclPtr = ReturnValue; 880 881 if (const RecordType *RecordTy = Ty->getAs<RecordType>()) { 882 if (!cast<CXXRecordDecl>(RecordTy->getDecl())->hasTrivialDestructor()) { 883 // Create a flag that is used to indicate when the NRVO was applied 884 // to this variable. Set it to zero to indicate that NRVO was not 885 // applied. 886 llvm::Value *Zero = Builder.getFalse(); 887 llvm::Value *NRVOFlag = CreateTempAlloca(Zero->getType(), "nrvo"); 888 EnsureInsertPoint(); 889 Builder.CreateStore(Zero, NRVOFlag); 890 891 // Record the NRVO flag for this variable. 892 NRVOFlags[&D] = NRVOFlag; 893 emission.NRVOFlag = NRVOFlag; 894 } 895 } 896 } else { 897 if (isByRef) 898 LTy = BuildByRefType(&D); 899 900 llvm::AllocaInst *Alloc = CreateTempAlloca(LTy); 901 Alloc->setName(D.getName()); 902 903 CharUnits allocaAlignment = alignment; 904 if (isByRef) 905 allocaAlignment = std::max(allocaAlignment, 906 getContext().toCharUnitsFromBits(getTarget().getPointerAlign(0))); 907 Alloc->setAlignment(allocaAlignment.getQuantity()); 908 DeclPtr = Alloc; 909 910 // Emit a lifetime intrinsic if meaningful. There's no point 911 // in doing this if we don't have a valid insertion point (?). 912 uint64_t size = CGM.getDataLayout().getTypeAllocSize(LTy); 913 if (HaveInsertPoint() && shouldUseLifetimeMarkers(*this, D, size)) { 914 llvm::Value *sizeV = llvm::ConstantInt::get(Int64Ty, size); 915 916 emission.SizeForLifetimeMarkers = sizeV; 917 llvm::Value *castAddr = Builder.CreateBitCast(Alloc, Int8PtrTy); 918 Builder.CreateCall2(CGM.getLLVMLifetimeStartFn(), sizeV, castAddr) 919 ->setDoesNotThrow(); 920 } else { 921 assert(!emission.useLifetimeMarkers()); 922 } 923 } 924 } else { 925 EnsureInsertPoint(); 926 927 if (!DidCallStackSave) { 928 // Save the stack. 929 llvm::Value *Stack = CreateTempAlloca(Int8PtrTy, "saved_stack"); 930 931 llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave); 932 llvm::Value *V = Builder.CreateCall(F); 933 934 Builder.CreateStore(V, Stack); 935 936 DidCallStackSave = true; 937 938 // Push a cleanup block and restore the stack there. 939 // FIXME: in general circumstances, this should be an EH cleanup. 940 EHStack.pushCleanup<CallStackRestore>(NormalCleanup, Stack); 941 } 942 943 llvm::Value *elementCount; 944 QualType elementType; 945 llvm::tie(elementCount, elementType) = getVLASize(Ty); 946 947 llvm::Type *llvmTy = ConvertTypeForMem(elementType); 948 949 // Allocate memory for the array. 950 llvm::AllocaInst *vla = Builder.CreateAlloca(llvmTy, elementCount, "vla"); 951 vla->setAlignment(alignment.getQuantity()); 952 953 DeclPtr = vla; 954 } 955 956 llvm::Value *&DMEntry = LocalDeclMap[&D]; 957 assert(DMEntry == 0 && "Decl already exists in localdeclmap!"); 958 DMEntry = DeclPtr; 959 emission.Address = DeclPtr; 960 961 // Emit debug info for local var declaration. 962 if (HaveInsertPoint()) 963 if (CGDebugInfo *DI = getDebugInfo()) { 964 if (CGM.getCodeGenOpts().getDebugInfo() 965 >= CodeGenOptions::LimitedDebugInfo) { 966 DI->setLocation(D.getLocation()); 967 DI->EmitDeclareOfAutoVariable(&D, DeclPtr, Builder); 968 } 969 } 970 971 if (D.hasAttr<AnnotateAttr>()) 972 EmitVarAnnotations(&D, emission.Address); 973 974 return emission; 975} 976 977/// Determines whether the given __block variable is potentially 978/// captured by the given expression. 979static bool isCapturedBy(const VarDecl &var, const Expr *e) { 980 // Skip the most common kinds of expressions that make 981 // hierarchy-walking expensive. 982 e = e->IgnoreParenCasts(); 983 984 if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) { 985 const BlockDecl *block = be->getBlockDecl(); 986 for (BlockDecl::capture_const_iterator i = block->capture_begin(), 987 e = block->capture_end(); i != e; ++i) { 988 if (i->getVariable() == &var) 989 return true; 990 } 991 992 // No need to walk into the subexpressions. 993 return false; 994 } 995 996 if (const StmtExpr *SE = dyn_cast<StmtExpr>(e)) { 997 const CompoundStmt *CS = SE->getSubStmt(); 998 for (CompoundStmt::const_body_iterator BI = CS->body_begin(), 999 BE = CS->body_end(); BI != BE; ++BI) 1000 if (Expr *E = dyn_cast<Expr>((*BI))) { 1001 if (isCapturedBy(var, E)) 1002 return true; 1003 } 1004 else if (DeclStmt *DS = dyn_cast<DeclStmt>((*BI))) { 1005 // special case declarations 1006 for (DeclStmt::decl_iterator I = DS->decl_begin(), E = DS->decl_end(); 1007 I != E; ++I) { 1008 if (VarDecl *VD = dyn_cast<VarDecl>((*I))) { 1009 Expr *Init = VD->getInit(); 1010 if (Init && isCapturedBy(var, Init)) 1011 return true; 1012 } 1013 } 1014 } 1015 else 1016 // FIXME. Make safe assumption assuming arbitrary statements cause capturing. 1017 // Later, provide code to poke into statements for capture analysis. 1018 return true; 1019 return false; 1020 } 1021 1022 for (Stmt::const_child_range children = e->children(); children; ++children) 1023 if (isCapturedBy(var, cast<Expr>(*children))) 1024 return true; 1025 1026 return false; 1027} 1028 1029/// \brief Determine whether the given initializer is trivial in the sense 1030/// that it requires no code to be generated. 1031static bool isTrivialInitializer(const Expr *Init) { 1032 if (!Init) 1033 return true; 1034 1035 if (const CXXConstructExpr *Construct = dyn_cast<CXXConstructExpr>(Init)) 1036 if (CXXConstructorDecl *Constructor = Construct->getConstructor()) 1037 if (Constructor->isTrivial() && 1038 Constructor->isDefaultConstructor() && 1039 !Construct->requiresZeroInitialization()) 1040 return true; 1041 1042 return false; 1043} 1044void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) { 1045 assert(emission.Variable && "emission was not valid!"); 1046 1047 // If this was emitted as a global constant, we're done. 1048 if (emission.wasEmittedAsGlobal()) return; 1049 1050 const VarDecl &D = *emission.Variable; 1051 QualType type = D.getType(); 1052 1053 // If this local has an initializer, emit it now. 1054 const Expr *Init = D.getInit(); 1055 1056 // If we are at an unreachable point, we don't need to emit the initializer 1057 // unless it contains a label. 1058 if (!HaveInsertPoint()) { 1059 if (!Init || !ContainsLabel(Init)) return; 1060 EnsureInsertPoint(); 1061 } 1062 1063 // Initialize the structure of a __block variable. 1064 if (emission.IsByRef) 1065 emitByrefStructureInit(emission); 1066 1067 if (isTrivialInitializer(Init)) 1068 return; 1069 1070 CharUnits alignment = emission.Alignment; 1071 1072 // Check whether this is a byref variable that's potentially 1073 // captured and moved by its own initializer. If so, we'll need to 1074 // emit the initializer first, then copy into the variable. 1075 bool capturedByInit = emission.IsByRef && isCapturedBy(D, Init); 1076 1077 llvm::Value *Loc = 1078 capturedByInit ? emission.Address : emission.getObjectAddress(*this); 1079 1080 llvm::Constant *constant = 0; 1081 if (emission.IsConstantAggregate) { 1082 assert(!capturedByInit && "constant init contains a capturing block?"); 1083 constant = CGM.EmitConstantInit(D, this); 1084 } 1085 1086 if (!constant) { 1087 LValue lv = MakeAddrLValue(Loc, type, alignment); 1088 lv.setNonGC(true); 1089 return EmitExprAsInit(Init, &D, lv, capturedByInit); 1090 } 1091 1092 // If this is a simple aggregate initialization, we can optimize it 1093 // in various ways. 1094 bool isVolatile = type.isVolatileQualified(); 1095 1096 llvm::Value *SizeVal = 1097 llvm::ConstantInt::get(IntPtrTy, 1098 getContext().getTypeSizeInChars(type).getQuantity()); 1099 1100 llvm::Type *BP = Int8PtrTy; 1101 if (Loc->getType() != BP) 1102 Loc = Builder.CreateBitCast(Loc, BP); 1103 1104 // If the initializer is all or mostly zeros, codegen with memset then do 1105 // a few stores afterward. 1106 if (shouldUseMemSetPlusStoresToInitialize(constant, 1107 CGM.getDataLayout().getTypeAllocSize(constant->getType()))) { 1108 Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, 0), SizeVal, 1109 alignment.getQuantity(), isVolatile); 1110 // Zero and undef don't require a stores. 1111 if (!constant->isNullValue() && !isa<llvm::UndefValue>(constant)) { 1112 Loc = Builder.CreateBitCast(Loc, constant->getType()->getPointerTo()); 1113 emitStoresForInitAfterMemset(constant, Loc, isVolatile, Builder); 1114 } 1115 } else { 1116 // Otherwise, create a temporary global with the initializer then 1117 // memcpy from the global to the alloca. 1118 std::string Name = GetStaticDeclName(*this, D, "."); 1119 llvm::GlobalVariable *GV = 1120 new llvm::GlobalVariable(CGM.getModule(), constant->getType(), true, 1121 llvm::GlobalValue::PrivateLinkage, 1122 constant, Name); 1123 GV->setAlignment(alignment.getQuantity()); 1124 GV->setUnnamedAddr(true); 1125 1126 llvm::Value *SrcPtr = GV; 1127 if (SrcPtr->getType() != BP) 1128 SrcPtr = Builder.CreateBitCast(SrcPtr, BP); 1129 1130 Builder.CreateMemCpy(Loc, SrcPtr, SizeVal, alignment.getQuantity(), 1131 isVolatile); 1132 } 1133} 1134 1135/// Emit an expression as an initializer for a variable at the given 1136/// location. The expression is not necessarily the normal 1137/// initializer for the variable, and the address is not necessarily 1138/// its normal location. 1139/// 1140/// \param init the initializing expression 1141/// \param var the variable to act as if we're initializing 1142/// \param loc the address to initialize; its type is a pointer 1143/// to the LLVM mapping of the variable's type 1144/// \param alignment the alignment of the address 1145/// \param capturedByInit true if the variable is a __block variable 1146/// whose address is potentially changed by the initializer 1147void CodeGenFunction::EmitExprAsInit(const Expr *init, 1148 const ValueDecl *D, 1149 LValue lvalue, 1150 bool capturedByInit) { 1151 QualType type = D->getType(); 1152 1153 if (type->isReferenceType()) { 1154 RValue rvalue = EmitReferenceBindingToExpr(init, D); 1155 if (capturedByInit) 1156 drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 1157 EmitStoreThroughLValue(rvalue, lvalue, true); 1158 return; 1159 } 1160 switch (getEvaluationKind(type)) { 1161 case TEK_Scalar: 1162 EmitScalarInit(init, D, lvalue, capturedByInit); 1163 return; 1164 case TEK_Complex: { 1165 ComplexPairTy complex = EmitComplexExpr(init); 1166 if (capturedByInit) 1167 drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 1168 EmitStoreOfComplex(complex, lvalue, /*init*/ true); 1169 return; 1170 } 1171 case TEK_Aggregate: 1172 if (type->isAtomicType()) { 1173 EmitAtomicInit(const_cast<Expr*>(init), lvalue); 1174 } else { 1175 // TODO: how can we delay here if D is captured by its initializer? 1176 EmitAggExpr(init, AggValueSlot::forLValue(lvalue, 1177 AggValueSlot::IsDestructed, 1178 AggValueSlot::DoesNotNeedGCBarriers, 1179 AggValueSlot::IsNotAliased)); 1180 } 1181 MaybeEmitStdInitializerListCleanup(lvalue.getAddress(), init); 1182 return; 1183 } 1184 llvm_unreachable("bad evaluation kind"); 1185} 1186 1187/// Enter a destroy cleanup for the given local variable. 1188void CodeGenFunction::emitAutoVarTypeCleanup( 1189 const CodeGenFunction::AutoVarEmission &emission, 1190 QualType::DestructionKind dtorKind) { 1191 assert(dtorKind != QualType::DK_none); 1192 1193 // Note that for __block variables, we want to destroy the 1194 // original stack object, not the possibly forwarded object. 1195 llvm::Value *addr = emission.getObjectAddress(*this); 1196 1197 const VarDecl *var = emission.Variable; 1198 QualType type = var->getType(); 1199 1200 CleanupKind cleanupKind = NormalAndEHCleanup; 1201 CodeGenFunction::Destroyer *destroyer = 0; 1202 1203 switch (dtorKind) { 1204 case QualType::DK_none: 1205 llvm_unreachable("no cleanup for trivially-destructible variable"); 1206 1207 case QualType::DK_cxx_destructor: 1208 // If there's an NRVO flag on the emission, we need a different 1209 // cleanup. 1210 if (emission.NRVOFlag) { 1211 assert(!type->isArrayType()); 1212 CXXDestructorDecl *dtor = type->getAsCXXRecordDecl()->getDestructor(); 1213 EHStack.pushCleanup<DestroyNRVOVariable>(cleanupKind, addr, dtor, 1214 emission.NRVOFlag); 1215 return; 1216 } 1217 break; 1218 1219 case QualType::DK_objc_strong_lifetime: 1220 // Suppress cleanups for pseudo-strong variables. 1221 if (var->isARCPseudoStrong()) return; 1222 1223 // Otherwise, consider whether to use an EH cleanup or not. 1224 cleanupKind = getARCCleanupKind(); 1225 1226 // Use the imprecise destroyer by default. 1227 if (!var->hasAttr<ObjCPreciseLifetimeAttr>()) 1228 destroyer = CodeGenFunction::destroyARCStrongImprecise; 1229 break; 1230 1231 case QualType::DK_objc_weak_lifetime: 1232 break; 1233 } 1234 1235 // If we haven't chosen a more specific destroyer, use the default. 1236 if (!destroyer) destroyer = getDestroyer(dtorKind); 1237 1238 // Use an EH cleanup in array destructors iff the destructor itself 1239 // is being pushed as an EH cleanup. 1240 bool useEHCleanup = (cleanupKind & EHCleanup); 1241 EHStack.pushCleanup<DestroyObject>(cleanupKind, addr, type, destroyer, 1242 useEHCleanup); 1243} 1244 1245void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) { 1246 assert(emission.Variable && "emission was not valid!"); 1247 1248 // If this was emitted as a global constant, we're done. 1249 if (emission.wasEmittedAsGlobal()) return; 1250 1251 // If we don't have an insertion point, we're done. Sema prevents 1252 // us from jumping into any of these scopes anyway. 1253 if (!HaveInsertPoint()) return; 1254 1255 const VarDecl &D = *emission.Variable; 1256 1257 // Make sure we call @llvm.lifetime.end. This needs to happen 1258 // *last*, so the cleanup needs to be pushed *first*. 1259 if (emission.useLifetimeMarkers()) { 1260 EHStack.pushCleanup<CallLifetimeEnd>(NormalCleanup, 1261 emission.getAllocatedAddress(), 1262 emission.getSizeForLifetimeMarkers()); 1263 } 1264 1265 // Check the type for a cleanup. 1266 if (QualType::DestructionKind dtorKind = D.getType().isDestructedType()) 1267 emitAutoVarTypeCleanup(emission, dtorKind); 1268 1269 // In GC mode, honor objc_precise_lifetime. 1270 if (getLangOpts().getGC() != LangOptions::NonGC && 1271 D.hasAttr<ObjCPreciseLifetimeAttr>()) { 1272 EHStack.pushCleanup<ExtendGCLifetime>(NormalCleanup, &D); 1273 } 1274 1275 // Handle the cleanup attribute. 1276 if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) { 1277 const FunctionDecl *FD = CA->getFunctionDecl(); 1278 1279 llvm::Constant *F = CGM.GetAddrOfFunction(FD); 1280 assert(F && "Could not find function!"); 1281 1282 const CGFunctionInfo &Info = CGM.getTypes().arrangeFunctionDeclaration(FD); 1283 EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup, F, &Info, &D); 1284 } 1285 1286 // If this is a block variable, call _Block_object_destroy 1287 // (on the unforwarded address). 1288 if (emission.IsByRef) 1289 enterByrefCleanup(emission); 1290} 1291 1292CodeGenFunction::Destroyer * 1293CodeGenFunction::getDestroyer(QualType::DestructionKind kind) { 1294 switch (kind) { 1295 case QualType::DK_none: llvm_unreachable("no destroyer for trivial dtor"); 1296 case QualType::DK_cxx_destructor: 1297 return destroyCXXObject; 1298 case QualType::DK_objc_strong_lifetime: 1299 return destroyARCStrongPrecise; 1300 case QualType::DK_objc_weak_lifetime: 1301 return destroyARCWeak; 1302 } 1303 llvm_unreachable("Unknown DestructionKind"); 1304} 1305 1306/// pushEHDestroy - Push the standard destructor for the given type as 1307/// an EH-only cleanup. 1308void CodeGenFunction::pushEHDestroy(QualType::DestructionKind dtorKind, 1309 llvm::Value *addr, QualType type) { 1310 assert(dtorKind && "cannot push destructor for trivial type"); 1311 assert(needsEHCleanup(dtorKind)); 1312 1313 pushDestroy(EHCleanup, addr, type, getDestroyer(dtorKind), true); 1314} 1315 1316/// pushDestroy - Push the standard destructor for the given type as 1317/// at least a normal cleanup. 1318void CodeGenFunction::pushDestroy(QualType::DestructionKind dtorKind, 1319 llvm::Value *addr, QualType type) { 1320 assert(dtorKind && "cannot push destructor for trivial type"); 1321 1322 CleanupKind cleanupKind = getCleanupKind(dtorKind); 1323 pushDestroy(cleanupKind, addr, type, getDestroyer(dtorKind), 1324 cleanupKind & EHCleanup); 1325} 1326 1327void CodeGenFunction::pushDestroy(CleanupKind cleanupKind, llvm::Value *addr, 1328 QualType type, Destroyer *destroyer, 1329 bool useEHCleanupForArray) { 1330 pushFullExprCleanup<DestroyObject>(cleanupKind, addr, type, 1331 destroyer, useEHCleanupForArray); 1332} 1333 1334/// emitDestroy - Immediately perform the destruction of the given 1335/// object. 1336/// 1337/// \param addr - the address of the object; a type* 1338/// \param type - the type of the object; if an array type, all 1339/// objects are destroyed in reverse order 1340/// \param destroyer - the function to call to destroy individual 1341/// elements 1342/// \param useEHCleanupForArray - whether an EH cleanup should be 1343/// used when destroying array elements, in case one of the 1344/// destructions throws an exception 1345void CodeGenFunction::emitDestroy(llvm::Value *addr, QualType type, 1346 Destroyer *destroyer, 1347 bool useEHCleanupForArray) { 1348 const ArrayType *arrayType = getContext().getAsArrayType(type); 1349 if (!arrayType) 1350 return destroyer(*this, addr, type); 1351 1352 llvm::Value *begin = addr; 1353 llvm::Value *length = emitArrayLength(arrayType, type, begin); 1354 1355 // Normally we have to check whether the array is zero-length. 1356 bool checkZeroLength = true; 1357 1358 // But if the array length is constant, we can suppress that. 1359 if (llvm::ConstantInt *constLength = dyn_cast<llvm::ConstantInt>(length)) { 1360 // ...and if it's constant zero, we can just skip the entire thing. 1361 if (constLength->isZero()) return; 1362 checkZeroLength = false; 1363 } 1364 1365 llvm::Value *end = Builder.CreateInBoundsGEP(begin, length); 1366 emitArrayDestroy(begin, end, type, destroyer, 1367 checkZeroLength, useEHCleanupForArray); 1368} 1369 1370/// emitArrayDestroy - Destroys all the elements of the given array, 1371/// beginning from last to first. The array cannot be zero-length. 1372/// 1373/// \param begin - a type* denoting the first element of the array 1374/// \param end - a type* denoting one past the end of the array 1375/// \param type - the element type of the array 1376/// \param destroyer - the function to call to destroy elements 1377/// \param useEHCleanup - whether to push an EH cleanup to destroy 1378/// the remaining elements in case the destruction of a single 1379/// element throws 1380void CodeGenFunction::emitArrayDestroy(llvm::Value *begin, 1381 llvm::Value *end, 1382 QualType type, 1383 Destroyer *destroyer, 1384 bool checkZeroLength, 1385 bool useEHCleanup) { 1386 assert(!type->isArrayType()); 1387 1388 // The basic structure here is a do-while loop, because we don't 1389 // need to check for the zero-element case. 1390 llvm::BasicBlock *bodyBB = createBasicBlock("arraydestroy.body"); 1391 llvm::BasicBlock *doneBB = createBasicBlock("arraydestroy.done"); 1392 1393 if (checkZeroLength) { 1394 llvm::Value *isEmpty = Builder.CreateICmpEQ(begin, end, 1395 "arraydestroy.isempty"); 1396 Builder.CreateCondBr(isEmpty, doneBB, bodyBB); 1397 } 1398 1399 // Enter the loop body, making that address the current address. 1400 llvm::BasicBlock *entryBB = Builder.GetInsertBlock(); 1401 EmitBlock(bodyBB); 1402 llvm::PHINode *elementPast = 1403 Builder.CreatePHI(begin->getType(), 2, "arraydestroy.elementPast"); 1404 elementPast->addIncoming(end, entryBB); 1405 1406 // Shift the address back by one element. 1407 llvm::Value *negativeOne = llvm::ConstantInt::get(SizeTy, -1, true); 1408 llvm::Value *element = Builder.CreateInBoundsGEP(elementPast, negativeOne, 1409 "arraydestroy.element"); 1410 1411 if (useEHCleanup) 1412 pushRegularPartialArrayCleanup(begin, element, type, destroyer); 1413 1414 // Perform the actual destruction there. 1415 destroyer(*this, element, type); 1416 1417 if (useEHCleanup) 1418 PopCleanupBlock(); 1419 1420 // Check whether we've reached the end. 1421 llvm::Value *done = Builder.CreateICmpEQ(element, begin, "arraydestroy.done"); 1422 Builder.CreateCondBr(done, doneBB, bodyBB); 1423 elementPast->addIncoming(element, Builder.GetInsertBlock()); 1424 1425 // Done. 1426 EmitBlock(doneBB); 1427} 1428 1429/// Perform partial array destruction as if in an EH cleanup. Unlike 1430/// emitArrayDestroy, the element type here may still be an array type. 1431static void emitPartialArrayDestroy(CodeGenFunction &CGF, 1432 llvm::Value *begin, llvm::Value *end, 1433 QualType type, 1434 CodeGenFunction::Destroyer *destroyer) { 1435 // If the element type is itself an array, drill down. 1436 unsigned arrayDepth = 0; 1437 while (const ArrayType *arrayType = CGF.getContext().getAsArrayType(type)) { 1438 // VLAs don't require a GEP index to walk into. 1439 if (!isa<VariableArrayType>(arrayType)) 1440 arrayDepth++; 1441 type = arrayType->getElementType(); 1442 } 1443 1444 if (arrayDepth) { 1445 llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, arrayDepth+1); 1446 1447 SmallVector<llvm::Value*,4> gepIndices(arrayDepth, zero); 1448 begin = CGF.Builder.CreateInBoundsGEP(begin, gepIndices, "pad.arraybegin"); 1449 end = CGF.Builder.CreateInBoundsGEP(end, gepIndices, "pad.arrayend"); 1450 } 1451 1452 // Destroy the array. We don't ever need an EH cleanup because we 1453 // assume that we're in an EH cleanup ourselves, so a throwing 1454 // destructor causes an immediate terminate. 1455 CGF.emitArrayDestroy(begin, end, type, destroyer, 1456 /*checkZeroLength*/ true, /*useEHCleanup*/ false); 1457} 1458 1459namespace { 1460 /// RegularPartialArrayDestroy - a cleanup which performs a partial 1461 /// array destroy where the end pointer is regularly determined and 1462 /// does not need to be loaded from a local. 1463 class RegularPartialArrayDestroy : public EHScopeStack::Cleanup { 1464 llvm::Value *ArrayBegin; 1465 llvm::Value *ArrayEnd; 1466 QualType ElementType; 1467 CodeGenFunction::Destroyer *Destroyer; 1468 public: 1469 RegularPartialArrayDestroy(llvm::Value *arrayBegin, llvm::Value *arrayEnd, 1470 QualType elementType, 1471 CodeGenFunction::Destroyer *destroyer) 1472 : ArrayBegin(arrayBegin), ArrayEnd(arrayEnd), 1473 ElementType(elementType), Destroyer(destroyer) {} 1474 1475 void Emit(CodeGenFunction &CGF, Flags flags) { 1476 emitPartialArrayDestroy(CGF, ArrayBegin, ArrayEnd, 1477 ElementType, Destroyer); 1478 } 1479 }; 1480 1481 /// IrregularPartialArrayDestroy - a cleanup which performs a 1482 /// partial array destroy where the end pointer is irregularly 1483 /// determined and must be loaded from a local. 1484 class IrregularPartialArrayDestroy : public EHScopeStack::Cleanup { 1485 llvm::Value *ArrayBegin; 1486 llvm::Value *ArrayEndPointer; 1487 QualType ElementType; 1488 CodeGenFunction::Destroyer *Destroyer; 1489 public: 1490 IrregularPartialArrayDestroy(llvm::Value *arrayBegin, 1491 llvm::Value *arrayEndPointer, 1492 QualType elementType, 1493 CodeGenFunction::Destroyer *destroyer) 1494 : ArrayBegin(arrayBegin), ArrayEndPointer(arrayEndPointer), 1495 ElementType(elementType), Destroyer(destroyer) {} 1496 1497 void Emit(CodeGenFunction &CGF, Flags flags) { 1498 llvm::Value *arrayEnd = CGF.Builder.CreateLoad(ArrayEndPointer); 1499 emitPartialArrayDestroy(CGF, ArrayBegin, arrayEnd, 1500 ElementType, Destroyer); 1501 } 1502 }; 1503} 1504 1505/// pushIrregularPartialArrayCleanup - Push an EH cleanup to destroy 1506/// already-constructed elements of the given array. The cleanup 1507/// may be popped with DeactivateCleanupBlock or PopCleanupBlock. 1508/// 1509/// \param elementType - the immediate element type of the array; 1510/// possibly still an array type 1511void CodeGenFunction::pushIrregularPartialArrayCleanup(llvm::Value *arrayBegin, 1512 llvm::Value *arrayEndPointer, 1513 QualType elementType, 1514 Destroyer *destroyer) { 1515 pushFullExprCleanup<IrregularPartialArrayDestroy>(EHCleanup, 1516 arrayBegin, arrayEndPointer, 1517 elementType, destroyer); 1518} 1519 1520/// pushRegularPartialArrayCleanup - Push an EH cleanup to destroy 1521/// already-constructed elements of the given array. The cleanup 1522/// may be popped with DeactivateCleanupBlock or PopCleanupBlock. 1523/// 1524/// \param elementType - the immediate element type of the array; 1525/// possibly still an array type 1526void CodeGenFunction::pushRegularPartialArrayCleanup(llvm::Value *arrayBegin, 1527 llvm::Value *arrayEnd, 1528 QualType elementType, 1529 Destroyer *destroyer) { 1530 pushFullExprCleanup<RegularPartialArrayDestroy>(EHCleanup, 1531 arrayBegin, arrayEnd, 1532 elementType, destroyer); 1533} 1534 1535/// Lazily declare the @llvm.lifetime.start intrinsic. 1536llvm::Constant *CodeGenModule::getLLVMLifetimeStartFn() { 1537 if (LifetimeStartFn) return LifetimeStartFn; 1538 LifetimeStartFn = llvm::Intrinsic::getDeclaration(&getModule(), 1539 llvm::Intrinsic::lifetime_start); 1540 return LifetimeStartFn; 1541} 1542 1543/// Lazily declare the @llvm.lifetime.end intrinsic. 1544llvm::Constant *CodeGenModule::getLLVMLifetimeEndFn() { 1545 if (LifetimeEndFn) return LifetimeEndFn; 1546 LifetimeEndFn = llvm::Intrinsic::getDeclaration(&getModule(), 1547 llvm::Intrinsic::lifetime_end); 1548 return LifetimeEndFn; 1549} 1550 1551namespace { 1552 /// A cleanup to perform a release of an object at the end of a 1553 /// function. This is used to balance out the incoming +1 of a 1554 /// ns_consumed argument when we can't reasonably do that just by 1555 /// not doing the initial retain for a __block argument. 1556 struct ConsumeARCParameter : EHScopeStack::Cleanup { 1557 ConsumeARCParameter(llvm::Value *param, 1558 ARCPreciseLifetime_t precise) 1559 : Param(param), Precise(precise) {} 1560 1561 llvm::Value *Param; 1562 ARCPreciseLifetime_t Precise; 1563 1564 void Emit(CodeGenFunction &CGF, Flags flags) { 1565 CGF.EmitARCRelease(Param, Precise); 1566 } 1567 }; 1568} 1569 1570/// Emit an alloca (or GlobalValue depending on target) 1571/// for the specified parameter and set up LocalDeclMap. 1572void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg, 1573 unsigned ArgNo) { 1574 // FIXME: Why isn't ImplicitParamDecl a ParmVarDecl? 1575 assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) && 1576 "Invalid argument to EmitParmDecl"); 1577 1578 Arg->setName(D.getName()); 1579 1580 QualType Ty = D.getType(); 1581 1582 // Use better IR generation for certain implicit parameters. 1583 if (isa<ImplicitParamDecl>(D)) { 1584 // The only implicit argument a block has is its literal. 1585 if (BlockInfo) { 1586 LocalDeclMap[&D] = Arg; 1587 llvm::Value *LocalAddr = 0; 1588 if (CGM.getCodeGenOpts().OptimizationLevel == 0) { 1589 // Allocate a stack slot to let the debug info survive the RA. 1590 llvm::AllocaInst *Alloc = CreateTempAlloca(ConvertTypeForMem(Ty), 1591 D.getName() + ".addr"); 1592 Alloc->setAlignment(getContext().getDeclAlign(&D).getQuantity()); 1593 LValue lv = MakeAddrLValue(Alloc, Ty, getContext().getDeclAlign(&D)); 1594 EmitStoreOfScalar(Arg, lv, /* isInitialization */ true); 1595 LocalAddr = Builder.CreateLoad(Alloc); 1596 } 1597 1598 if (CGDebugInfo *DI = getDebugInfo()) { 1599 if (CGM.getCodeGenOpts().getDebugInfo() 1600 >= CodeGenOptions::LimitedDebugInfo) { 1601 DI->setLocation(D.getLocation()); 1602 DI->EmitDeclareOfBlockLiteralArgVariable(*BlockInfo, Arg, LocalAddr, Builder); 1603 } 1604 } 1605 1606 return; 1607 } 1608 } 1609 1610 llvm::Value *DeclPtr; 1611 // If this is an aggregate or variable sized value, reuse the input pointer. 1612 if (!Ty->isConstantSizeType() || 1613 !CodeGenFunction::hasScalarEvaluationKind(Ty)) { 1614 DeclPtr = Arg; 1615 } else { 1616 // Otherwise, create a temporary to hold the value. 1617 llvm::AllocaInst *Alloc = CreateTempAlloca(ConvertTypeForMem(Ty), 1618 D.getName() + ".addr"); 1619 CharUnits Align = getContext().getDeclAlign(&D); 1620 Alloc->setAlignment(Align.getQuantity()); 1621 DeclPtr = Alloc; 1622 1623 bool doStore = true; 1624 1625 Qualifiers qs = Ty.getQualifiers(); 1626 LValue lv = MakeAddrLValue(DeclPtr, Ty, Align); 1627 if (Qualifiers::ObjCLifetime lt = qs.getObjCLifetime()) { 1628 // We honor __attribute__((ns_consumed)) for types with lifetime. 1629 // For __strong, it's handled by just skipping the initial retain; 1630 // otherwise we have to balance out the initial +1 with an extra 1631 // cleanup to do the release at the end of the function. 1632 bool isConsumed = D.hasAttr<NSConsumedAttr>(); 1633 1634 // 'self' is always formally __strong, but if this is not an 1635 // init method then we don't want to retain it. 1636 if (D.isARCPseudoStrong()) { 1637 const ObjCMethodDecl *method = cast<ObjCMethodDecl>(CurCodeDecl); 1638 assert(&D == method->getSelfDecl()); 1639 assert(lt == Qualifiers::OCL_Strong); 1640 assert(qs.hasConst()); 1641 assert(method->getMethodFamily() != OMF_init); 1642 (void) method; 1643 lt = Qualifiers::OCL_ExplicitNone; 1644 } 1645 1646 if (lt == Qualifiers::OCL_Strong) { 1647 if (!isConsumed) { 1648 if (CGM.getCodeGenOpts().OptimizationLevel == 0) { 1649 // use objc_storeStrong(&dest, value) for retaining the 1650 // object. But first, store a null into 'dest' because 1651 // objc_storeStrong attempts to release its old value. 1652 llvm::Value * Null = CGM.EmitNullConstant(D.getType()); 1653 EmitStoreOfScalar(Null, lv, /* isInitialization */ true); 1654 EmitARCStoreStrongCall(lv.getAddress(), Arg, true); 1655 doStore = false; 1656 } 1657 else 1658 // Don't use objc_retainBlock for block pointers, because we 1659 // don't want to Block_copy something just because we got it 1660 // as a parameter. 1661 Arg = EmitARCRetainNonBlock(Arg); 1662 } 1663 } else { 1664 // Push the cleanup for a consumed parameter. 1665 if (isConsumed) { 1666 ARCPreciseLifetime_t precise = (D.hasAttr<ObjCPreciseLifetimeAttr>() 1667 ? ARCPreciseLifetime : ARCImpreciseLifetime); 1668 EHStack.pushCleanup<ConsumeARCParameter>(getARCCleanupKind(), Arg, 1669 precise); 1670 } 1671 1672 if (lt == Qualifiers::OCL_Weak) { 1673 EmitARCInitWeak(DeclPtr, Arg); 1674 doStore = false; // The weak init is a store, no need to do two. 1675 } 1676 } 1677 1678 // Enter the cleanup scope. 1679 EmitAutoVarWithLifetime(*this, D, DeclPtr, lt); 1680 } 1681 1682 // Store the initial value into the alloca. 1683 if (doStore) 1684 EmitStoreOfScalar(Arg, lv, /* isInitialization */ true); 1685 } 1686 1687 llvm::Value *&DMEntry = LocalDeclMap[&D]; 1688 assert(DMEntry == 0 && "Decl already exists in localdeclmap!"); 1689 DMEntry = DeclPtr; 1690 1691 // Emit debug info for param declaration. 1692 if (CGDebugInfo *DI = getDebugInfo()) { 1693 if (CGM.getCodeGenOpts().getDebugInfo() 1694 >= CodeGenOptions::LimitedDebugInfo) { 1695 DI->EmitDeclareOfArgVariable(&D, DeclPtr, ArgNo, Builder); 1696 } 1697 } 1698 1699 if (D.hasAttr<AnnotateAttr>()) 1700 EmitVarAnnotations(&D, DeclPtr); 1701} 1702