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::ObjCClass: 69 case Decl::ObjCForwardProtocol: 70 case Decl::FileScopeAsm: 71 case Decl::Friend: 72 case Decl::FriendTemplate: 73 case Decl::Block: 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::UsingDirective: // using namespace X; [C++] 84 case Decl::NamespaceAlias: 85 case Decl::StaticAssert: // static_assert(X, ""); [C++0x] 86 case Decl::Label: // __label__ x; 87 // None of these decls require codegen support. 88 return; 89 90 case Decl::Var: { 91 const VarDecl &VD = cast<VarDecl>(D); 92 assert(VD.isLocalVarDecl() && 93 "Should not see file-scope variables inside a function!"); 94 return EmitVarDecl(VD); 95 } 96 97 case Decl::Typedef: // typedef int X; 98 case Decl::TypeAlias: { // using X = int; [C++0x] 99 const TypedefNameDecl &TD = cast<TypedefNameDecl>(D); 100 QualType Ty = TD.getUnderlyingType(); 101 102 if (Ty->isVariablyModifiedType()) 103 EmitVariablyModifiedType(Ty); 104 } 105 } 106 } 107 108 /// EmitVarDecl - This method handles emission of any variable declaration 109 /// inside a function, including static vars etc. 110 void CodeGenFunction::EmitVarDecl(const VarDecl &D) { 111 switch (D.getStorageClass()) { 112 case SC_None: 113 case SC_Auto: 114 case SC_Register: 115 return EmitAutoVarDecl(D); 116 case SC_Static: { 117 llvm::GlobalValue::LinkageTypes Linkage = 118 llvm::GlobalValue::InternalLinkage; 119 120 // If the function definition has some sort of weak linkage, its 121 // static variables should also be weak so that they get properly 122 // uniqued. We can't do this in C, though, because there's no 123 // standard way to agree on which variables are the same (i.e. 124 // there's no mangling). 125 if (getContext().getLangOptions().CPlusPlus) 126 if (llvm::GlobalValue::isWeakForLinker(CurFn->getLinkage())) 127 Linkage = CurFn->getLinkage(); 128 129 return EmitStaticVarDecl(D, Linkage); 130 } 131 case SC_Extern: 132 case SC_PrivateExtern: 133 // Don't emit it now, allow it to be emitted lazily on its first use. 134 return; 135 case SC_OpenCLWorkGroupLocal: 136 return CGM.getOpenCLRuntime().EmitWorkGroupLocalVarDecl(*this, D); 137 } 138 139 llvm_unreachable("Unknown storage class"); 140 } 141 142 static std::string GetStaticDeclName(CodeGenFunction &CGF, const VarDecl &D, 143 const char *Separator) { 144 CodeGenModule &CGM = CGF.CGM; 145 if (CGF.getContext().getLangOptions().CPlusPlus) { 146 StringRef Name = CGM.getMangledName(&D); 147 return Name.str(); 148 } 149 150 std::string ContextName; 151 if (!CGF.CurFuncDecl) { 152 // Better be in a block declared in global scope. 153 const NamedDecl *ND = cast<NamedDecl>(&D); 154 const DeclContext *DC = ND->getDeclContext(); 155 if (const BlockDecl *BD = dyn_cast<BlockDecl>(DC)) { 156 MangleBuffer Name; 157 CGM.getBlockMangledName(GlobalDecl(), Name, BD); 158 ContextName = Name.getString(); 159 } 160 else 161 llvm_unreachable("Unknown context for block static var decl"); 162 } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CGF.CurFuncDecl)) { 163 StringRef Name = CGM.getMangledName(FD); 164 ContextName = Name.str(); 165 } else if (isa<ObjCMethodDecl>(CGF.CurFuncDecl)) 166 ContextName = CGF.CurFn->getName(); 167 else 168 llvm_unreachable("Unknown context for static var decl"); 169 170 return ContextName + Separator + D.getNameAsString(); 171 } 172 173 llvm::GlobalVariable * 174 CodeGenFunction::CreateStaticVarDecl(const VarDecl &D, 175 const char *Separator, 176 llvm::GlobalValue::LinkageTypes Linkage) { 177 QualType Ty = D.getType(); 178 assert(Ty->isConstantSizeType() && "VLAs can't be static"); 179 180 std::string Name = GetStaticDeclName(*this, D, Separator); 181 182 llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(Ty); 183 llvm::GlobalVariable *GV = 184 new llvm::GlobalVariable(CGM.getModule(), LTy, 185 Ty.isConstant(getContext()), Linkage, 186 CGM.EmitNullConstant(D.getType()), Name, 0, 187 D.isThreadSpecified(), 188 CGM.getContext().getTargetAddressSpace(Ty)); 189 GV->setAlignment(getContext().getDeclAlign(&D).getQuantity()); 190 if (Linkage != llvm::GlobalValue::InternalLinkage) 191 GV->setVisibility(CurFn->getVisibility()); 192 return GV; 193 } 194 195 /// AddInitializerToStaticVarDecl - Add the initializer for 'D' to the 196 /// global variable that has already been created for it. If the initializer 197 /// has a different type than GV does, this may free GV and return a different 198 /// one. Otherwise it just returns GV. 199 llvm::GlobalVariable * 200 CodeGenFunction::AddInitializerToStaticVarDecl(const VarDecl &D, 201 llvm::GlobalVariable *GV) { 202 llvm::Constant *Init = CGM.EmitConstantExpr(D.getInit(), D.getType(), this); 203 204 // If constant emission failed, then this should be a C++ static 205 // initializer. 206 if (!Init) { 207 if (!getContext().getLangOptions().CPlusPlus) 208 CGM.ErrorUnsupported(D.getInit(), "constant l-value expression"); 209 else if (Builder.GetInsertBlock()) { 210 // Since we have a static initializer, this global variable can't 211 // be constant. 212 GV->setConstant(false); 213 214 EmitCXXGuardedInit(D, GV); 215 } 216 return GV; 217 } 218 219 // The initializer may differ in type from the global. Rewrite 220 // the global to match the initializer. (We have to do this 221 // because some types, like unions, can't be completely represented 222 // in the LLVM type system.) 223 if (GV->getType()->getElementType() != Init->getType()) { 224 llvm::GlobalVariable *OldGV = GV; 225 226 GV = new llvm::GlobalVariable(CGM.getModule(), Init->getType(), 227 OldGV->isConstant(), 228 OldGV->getLinkage(), Init, "", 229 /*InsertBefore*/ OldGV, 230 D.isThreadSpecified(), 231 CGM.getContext().getTargetAddressSpace(D.getType())); 232 GV->setVisibility(OldGV->getVisibility()); 233 234 // Steal the name of the old global 235 GV->takeName(OldGV); 236 237 // Replace all uses of the old global with the new global 238 llvm::Constant *NewPtrForOldDecl = 239 llvm::ConstantExpr::getBitCast(GV, OldGV->getType()); 240 OldGV->replaceAllUsesWith(NewPtrForOldDecl); 241 242 // Erase the old global, since it is no longer used. 243 OldGV->eraseFromParent(); 244 } 245 246 GV->setInitializer(Init); 247 return GV; 248 } 249 250 void CodeGenFunction::EmitStaticVarDecl(const VarDecl &D, 251 llvm::GlobalValue::LinkageTypes Linkage) { 252 llvm::Value *&DMEntry = LocalDeclMap[&D]; 253 assert(DMEntry == 0 && "Decl already exists in localdeclmap!"); 254 255 llvm::GlobalVariable *GV = CreateStaticVarDecl(D, ".", Linkage); 256 257 // Store into LocalDeclMap before generating initializer to handle 258 // circular references. 259 DMEntry = GV; 260 261 // We can't have a VLA here, but we can have a pointer to a VLA, 262 // even though that doesn't really make any sense. 263 // Make sure to evaluate VLA bounds now so that we have them for later. 264 if (D.getType()->isVariablyModifiedType()) 265 EmitVariablyModifiedType(D.getType()); 266 267 // Local static block variables must be treated as globals as they may be 268 // referenced in their RHS initializer block-literal expresion. 269 CGM.setStaticLocalDeclAddress(&D, GV); 270 271 // If this value has an initializer, emit it. 272 if (D.getInit()) 273 GV = AddInitializerToStaticVarDecl(D, GV); 274 275 GV->setAlignment(getContext().getDeclAlign(&D).getQuantity()); 276 277 if (D.hasAttr<AnnotateAttr>()) 278 CGM.AddGlobalAnnotations(&D, GV); 279 280 if (const SectionAttr *SA = D.getAttr<SectionAttr>()) 281 GV->setSection(SA->getName()); 282 283 if (D.hasAttr<UsedAttr>()) 284 CGM.AddUsedGlobal(GV); 285 286 // We may have to cast the constant because of the initializer 287 // mismatch above. 288 // 289 // FIXME: It is really dangerous to store this in the map; if anyone 290 // RAUW's the GV uses of this constant will be invalid. 291 llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(D.getType()); 292 llvm::Type *LPtrTy = 293 LTy->getPointerTo(CGM.getContext().getTargetAddressSpace(D.getType())); 294 DMEntry = llvm::ConstantExpr::getBitCast(GV, LPtrTy); 295 296 // Emit global variable debug descriptor for static vars. 297 CGDebugInfo *DI = getDebugInfo(); 298 if (DI) { 299 DI->setLocation(D.getLocation()); 300 DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(GV), &D); 301 } 302 } 303 304 namespace { 305 struct DestroyObject : EHScopeStack::Cleanup { 306 DestroyObject(llvm::Value *addr, QualType type, 307 CodeGenFunction::Destroyer *destroyer, 308 bool useEHCleanupForArray) 309 : addr(addr), type(type), destroyer(*destroyer), 310 useEHCleanupForArray(useEHCleanupForArray) {} 311 312 llvm::Value *addr; 313 QualType type; 314 CodeGenFunction::Destroyer &destroyer; 315 bool useEHCleanupForArray; 316 317 void Emit(CodeGenFunction &CGF, Flags flags) { 318 // Don't use an EH cleanup recursively from an EH cleanup. 319 bool useEHCleanupForArray = 320 flags.isForNormalCleanup() && this->useEHCleanupForArray; 321 322 CGF.emitDestroy(addr, type, destroyer, useEHCleanupForArray); 323 } 324 }; 325 326 struct DestroyNRVOVariable : EHScopeStack::Cleanup { 327 DestroyNRVOVariable(llvm::Value *addr, 328 const CXXDestructorDecl *Dtor, 329 llvm::Value *NRVOFlag) 330 : Dtor(Dtor), NRVOFlag(NRVOFlag), Loc(addr) {} 331 332 const CXXDestructorDecl *Dtor; 333 llvm::Value *NRVOFlag; 334 llvm::Value *Loc; 335 336 void Emit(CodeGenFunction &CGF, Flags flags) { 337 // Along the exceptions path we always execute the dtor. 338 bool NRVO = flags.isForNormalCleanup() && NRVOFlag; 339 340 llvm::BasicBlock *SkipDtorBB = 0; 341 if (NRVO) { 342 // If we exited via NRVO, we skip the destructor call. 343 llvm::BasicBlock *RunDtorBB = CGF.createBasicBlock("nrvo.unused"); 344 SkipDtorBB = CGF.createBasicBlock("nrvo.skipdtor"); 345 llvm::Value *DidNRVO = CGF.Builder.CreateLoad(NRVOFlag, "nrvo.val"); 346 CGF.Builder.CreateCondBr(DidNRVO, SkipDtorBB, RunDtorBB); 347 CGF.EmitBlock(RunDtorBB); 348 } 349 350 CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete, 351 /*ForVirtualBase=*/false, Loc); 352 353 if (NRVO) CGF.EmitBlock(SkipDtorBB); 354 } 355 }; 356 357 struct CallStackRestore : EHScopeStack::Cleanup { 358 llvm::Value *Stack; 359 CallStackRestore(llvm::Value *Stack) : Stack(Stack) {} 360 void Emit(CodeGenFunction &CGF, Flags flags) { 361 llvm::Value *V = CGF.Builder.CreateLoad(Stack); 362 llvm::Value *F = CGF.CGM.getIntrinsic(llvm::Intrinsic::stackrestore); 363 CGF.Builder.CreateCall(F, V); 364 } 365 }; 366 367 struct ExtendGCLifetime : EHScopeStack::Cleanup { 368 const VarDecl &Var; 369 ExtendGCLifetime(const VarDecl *var) : Var(*var) {} 370 371 void Emit(CodeGenFunction &CGF, Flags flags) { 372 // Compute the address of the local variable, in case it's a 373 // byref or something. 374 DeclRefExpr DRE(const_cast<VarDecl*>(&Var), Var.getType(), VK_LValue, 375 SourceLocation()); 376 llvm::Value *value = CGF.EmitLoadOfScalar(CGF.EmitDeclRefLValue(&DRE)); 377 CGF.EmitExtendGCLifetime(value); 378 } 379 }; 380 381 struct CallCleanupFunction : EHScopeStack::Cleanup { 382 llvm::Constant *CleanupFn; 383 const CGFunctionInfo &FnInfo; 384 const VarDecl &Var; 385 386 CallCleanupFunction(llvm::Constant *CleanupFn, const CGFunctionInfo *Info, 387 const VarDecl *Var) 388 : CleanupFn(CleanupFn), FnInfo(*Info), Var(*Var) {} 389 390 void Emit(CodeGenFunction &CGF, Flags flags) { 391 DeclRefExpr DRE(const_cast<VarDecl*>(&Var), Var.getType(), VK_LValue, 392 SourceLocation()); 393 // Compute the address of the local variable, in case it's a byref 394 // or something. 395 llvm::Value *Addr = CGF.EmitDeclRefLValue(&DRE).getAddress(); 396 397 // In some cases, the type of the function argument will be different from 398 // the type of the pointer. An example of this is 399 // void f(void* arg); 400 // __attribute__((cleanup(f))) void *g; 401 // 402 // To fix this we insert a bitcast here. 403 QualType ArgTy = FnInfo.arg_begin()->type; 404 llvm::Value *Arg = 405 CGF.Builder.CreateBitCast(Addr, CGF.ConvertType(ArgTy)); 406 407 CallArgList Args; 408 Args.add(RValue::get(Arg), 409 CGF.getContext().getPointerType(Var.getType())); 410 CGF.EmitCall(FnInfo, CleanupFn, ReturnValueSlot(), Args); 411 } 412 }; 413 } 414 415 /// EmitAutoVarWithLifetime - Does the setup required for an automatic 416 /// variable with lifetime. 417 static void EmitAutoVarWithLifetime(CodeGenFunction &CGF, const VarDecl &var, 418 llvm::Value *addr, 419 Qualifiers::ObjCLifetime lifetime) { 420 switch (lifetime) { 421 case Qualifiers::OCL_None: 422 llvm_unreachable("present but none"); 423 424 case Qualifiers::OCL_ExplicitNone: 425 // nothing to do 426 break; 427 428 case Qualifiers::OCL_Strong: { 429 CodeGenFunction::Destroyer &destroyer = 430 (var.hasAttr<ObjCPreciseLifetimeAttr>() 431 ? CodeGenFunction::destroyARCStrongPrecise 432 : CodeGenFunction::destroyARCStrongImprecise); 433 434 CleanupKind cleanupKind = CGF.getARCCleanupKind(); 435 CGF.pushDestroy(cleanupKind, addr, var.getType(), destroyer, 436 cleanupKind & EHCleanup); 437 break; 438 } 439 case Qualifiers::OCL_Autoreleasing: 440 // nothing to do 441 break; 442 443 case Qualifiers::OCL_Weak: 444 // __weak objects always get EH cleanups; otherwise, exceptions 445 // could cause really nasty crashes instead of mere leaks. 446 CGF.pushDestroy(NormalAndEHCleanup, addr, var.getType(), 447 CodeGenFunction::destroyARCWeak, 448 /*useEHCleanup*/ true); 449 break; 450 } 451 } 452 453 static bool isAccessedBy(const VarDecl &var, const Stmt *s) { 454 if (const Expr *e = dyn_cast<Expr>(s)) { 455 // Skip the most common kinds of expressions that make 456 // hierarchy-walking expensive. 457 s = e = e->IgnoreParenCasts(); 458 459 if (const DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e)) 460 return (ref->getDecl() == &var); 461 } 462 463 for (Stmt::const_child_range children = s->children(); children; ++children) 464 // children might be null; as in missing decl or conditional of an if-stmt. 465 if ((*children) && isAccessedBy(var, *children)) 466 return true; 467 468 return false; 469 } 470 471 static bool isAccessedBy(const ValueDecl *decl, const Expr *e) { 472 if (!decl) return false; 473 if (!isa<VarDecl>(decl)) return false; 474 const VarDecl *var = cast<VarDecl>(decl); 475 return isAccessedBy(*var, e); 476 } 477 478 static void drillIntoBlockVariable(CodeGenFunction &CGF, 479 LValue &lvalue, 480 const VarDecl *var) { 481 lvalue.setAddress(CGF.BuildBlockByrefAddress(lvalue.getAddress(), var)); 482 } 483 484 void CodeGenFunction::EmitScalarInit(const Expr *init, 485 const ValueDecl *D, 486 LValue lvalue, 487 bool capturedByInit) { 488 Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime(); 489 if (!lifetime) { 490 llvm::Value *value = EmitScalarExpr(init); 491 if (capturedByInit) 492 drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 493 EmitStoreThroughLValue(RValue::get(value), lvalue); 494 return; 495 } 496 497 // If we're emitting a value with lifetime, we have to do the 498 // initialization *before* we leave the cleanup scopes. 499 CodeGenFunction::RunCleanupsScope Scope(*this); 500 if (const ExprWithCleanups *ewc = dyn_cast<ExprWithCleanups>(init)) 501 init = ewc->getSubExpr(); 502 503 // We have to maintain the illusion that the variable is 504 // zero-initialized. If the variable might be accessed in its 505 // initializer, zero-initialize before running the initializer, then 506 // actually perform the initialization with an assign. 507 bool accessedByInit = false; 508 if (lifetime != Qualifiers::OCL_ExplicitNone) 509 accessedByInit = (capturedByInit || isAccessedBy(D, init)); 510 if (accessedByInit) { 511 LValue tempLV = lvalue; 512 // Drill down to the __block object if necessary. 513 if (capturedByInit) { 514 // We can use a simple GEP for this because it can't have been 515 // moved yet. 516 tempLV.setAddress(Builder.CreateStructGEP(tempLV.getAddress(), 517 getByRefValueLLVMField(cast<VarDecl>(D)))); 518 } 519 520 llvm::PointerType *ty 521 = cast<llvm::PointerType>(tempLV.getAddress()->getType()); 522 ty = cast<llvm::PointerType>(ty->getElementType()); 523 524 llvm::Value *zero = llvm::ConstantPointerNull::get(ty); 525 526 // If __weak, we want to use a barrier under certain conditions. 527 if (lifetime == Qualifiers::OCL_Weak) 528 EmitARCInitWeak(tempLV.getAddress(), zero); 529 530 // Otherwise just do a simple store. 531 else 532 EmitStoreOfScalar(zero, tempLV); 533 } 534 535 // Emit the initializer. 536 llvm::Value *value = 0; 537 538 switch (lifetime) { 539 case Qualifiers::OCL_None: 540 llvm_unreachable("present but none"); 541 542 case Qualifiers::OCL_ExplicitNone: 543 // nothing to do 544 value = EmitScalarExpr(init); 545 break; 546 547 case Qualifiers::OCL_Strong: { 548 value = EmitARCRetainScalarExpr(init); 549 break; 550 } 551 552 case Qualifiers::OCL_Weak: { 553 // No way to optimize a producing initializer into this. It's not 554 // worth optimizing for, because the value will immediately 555 // disappear in the common case. 556 value = EmitScalarExpr(init); 557 558 if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 559 if (accessedByInit) 560 EmitARCStoreWeak(lvalue.getAddress(), value, /*ignored*/ true); 561 else 562 EmitARCInitWeak(lvalue.getAddress(), value); 563 return; 564 } 565 566 case Qualifiers::OCL_Autoreleasing: 567 value = EmitARCRetainAutoreleaseScalarExpr(init); 568 break; 569 } 570 571 if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 572 573 // If the variable might have been accessed by its initializer, we 574 // might have to initialize with a barrier. We have to do this for 575 // both __weak and __strong, but __weak got filtered out above. 576 if (accessedByInit && lifetime == Qualifiers::OCL_Strong) { 577 llvm::Value *oldValue = EmitLoadOfScalar(lvalue); 578 EmitStoreOfScalar(value, lvalue); 579 EmitARCRelease(oldValue, /*precise*/ false); 580 return; 581 } 582 583 EmitStoreOfScalar(value, lvalue); 584 } 585 586 /// EmitScalarInit - Initialize the given lvalue with the given object. 587 void CodeGenFunction::EmitScalarInit(llvm::Value *init, LValue lvalue) { 588 Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime(); 589 if (!lifetime) 590 return EmitStoreThroughLValue(RValue::get(init), lvalue); 591 592 switch (lifetime) { 593 case Qualifiers::OCL_None: 594 llvm_unreachable("present but none"); 595 596 case Qualifiers::OCL_ExplicitNone: 597 // nothing to do 598 break; 599 600 case Qualifiers::OCL_Strong: 601 init = EmitARCRetain(lvalue.getType(), init); 602 break; 603 604 case Qualifiers::OCL_Weak: 605 // Initialize and then skip the primitive store. 606 EmitARCInitWeak(lvalue.getAddress(), init); 607 return; 608 609 case Qualifiers::OCL_Autoreleasing: 610 init = EmitARCRetainAutorelease(lvalue.getType(), init); 611 break; 612 } 613 614 EmitStoreOfScalar(init, lvalue); 615 } 616 617 /// canEmitInitWithFewStoresAfterMemset - Decide whether we can emit the 618 /// non-zero parts of the specified initializer with equal or fewer than 619 /// NumStores scalar stores. 620 static bool canEmitInitWithFewStoresAfterMemset(llvm::Constant *Init, 621 unsigned &NumStores) { 622 // Zero and Undef never requires any extra stores. 623 if (isa<llvm::ConstantAggregateZero>(Init) || 624 isa<llvm::ConstantPointerNull>(Init) || 625 isa<llvm::UndefValue>(Init)) 626 return true; 627 if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) || 628 isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) || 629 isa<llvm::ConstantExpr>(Init)) 630 return Init->isNullValue() || NumStores--; 631 632 // See if we can emit each element. 633 if (isa<llvm::ConstantArray>(Init) || isa<llvm::ConstantStruct>(Init)) { 634 for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) { 635 llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i)); 636 if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores)) 637 return false; 638 } 639 return true; 640 } 641 642 // Anything else is hard and scary. 643 return false; 644 } 645 646 /// emitStoresForInitAfterMemset - For inits that 647 /// canEmitInitWithFewStoresAfterMemset returned true for, emit the scalar 648 /// stores that would be required. 649 static void emitStoresForInitAfterMemset(llvm::Constant *Init, llvm::Value *Loc, 650 bool isVolatile, CGBuilderTy &Builder) { 651 // Zero doesn't require any stores. 652 if (isa<llvm::ConstantAggregateZero>(Init) || 653 isa<llvm::ConstantPointerNull>(Init) || 654 isa<llvm::UndefValue>(Init)) 655 return; 656 657 if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) || 658 isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) || 659 isa<llvm::ConstantExpr>(Init)) { 660 if (!Init->isNullValue()) 661 Builder.CreateStore(Init, Loc, isVolatile); 662 return; 663 } 664 665 assert((isa<llvm::ConstantStruct>(Init) || isa<llvm::ConstantArray>(Init)) && 666 "Unknown value type!"); 667 668 for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) { 669 llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i)); 670 if (Elt->isNullValue()) continue; 671 672 // Otherwise, get a pointer to the element and emit it. 673 emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i), 674 isVolatile, Builder); 675 } 676 } 677 678 679 /// shouldUseMemSetPlusStoresToInitialize - Decide whether we should use memset 680 /// plus some stores to initialize a local variable instead of using a memcpy 681 /// from a constant global. It is beneficial to use memset if the global is all 682 /// zeros, or mostly zeros and large. 683 static bool shouldUseMemSetPlusStoresToInitialize(llvm::Constant *Init, 684 uint64_t GlobalSize) { 685 // If a global is all zeros, always use a memset. 686 if (isa<llvm::ConstantAggregateZero>(Init)) return true; 687 688 689 // If a non-zero global is <= 32 bytes, always use a memcpy. If it is large, 690 // do it if it will require 6 or fewer scalar stores. 691 // TODO: Should budget depends on the size? Avoiding a large global warrants 692 // plopping in more stores. 693 unsigned StoreBudget = 6; 694 uint64_t SizeLimit = 32; 695 696 return GlobalSize > SizeLimit && 697 canEmitInitWithFewStoresAfterMemset(Init, StoreBudget); 698 } 699 700 701 /// EmitAutoVarDecl - Emit code and set up an entry in LocalDeclMap for a 702 /// variable declaration with auto, register, or no storage class specifier. 703 /// These turn into simple stack objects, or GlobalValues depending on target. 704 void CodeGenFunction::EmitAutoVarDecl(const VarDecl &D) { 705 AutoVarEmission emission = EmitAutoVarAlloca(D); 706 EmitAutoVarInit(emission); 707 EmitAutoVarCleanups(emission); 708 } 709 710 /// EmitAutoVarAlloca - Emit the alloca and debug information for a 711 /// local variable. Does not emit initalization or destruction. 712 CodeGenFunction::AutoVarEmission 713 CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) { 714 QualType Ty = D.getType(); 715 716 AutoVarEmission emission(D); 717 718 bool isByRef = D.hasAttr<BlocksAttr>(); 719 emission.IsByRef = isByRef; 720 721 CharUnits alignment = getContext().getDeclAlign(&D); 722 emission.Alignment = alignment; 723 724 // If the type is variably-modified, emit all the VLA sizes for it. 725 if (Ty->isVariablyModifiedType()) 726 EmitVariablyModifiedType(Ty); 727 728 llvm::Value *DeclPtr; 729 if (Ty->isConstantSizeType()) { 730 if (!Target.useGlobalsForAutomaticVariables()) { 731 bool NRVO = getContext().getLangOptions().ElideConstructors && 732 D.isNRVOVariable(); 733 734 // If this value is a POD array or struct with a statically 735 // determinable constant initializer, there are optimizations we 736 // can do. 737 // TODO: we can potentially constant-evaluate non-POD structs and 738 // arrays as long as the initialization is trivial (e.g. if they 739 // have a non-trivial destructor, but not a non-trivial constructor). 740 if (D.getInit() && 741 (Ty->isArrayType() || Ty->isRecordType()) && 742 (Ty.isPODType(getContext()) || 743 getContext().getBaseElementType(Ty)->isObjCObjectPointerType()) && 744 D.getInit()->isConstantInitializer(getContext(), false)) { 745 746 // If the variable's a const type, and it's neither an NRVO 747 // candidate nor a __block variable, emit it as a global instead. 748 if (CGM.getCodeGenOpts().MergeAllConstants && Ty.isConstQualified() && 749 !NRVO && !isByRef) { 750 EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage); 751 752 emission.Address = 0; // signal this condition to later callbacks 753 assert(emission.wasEmittedAsGlobal()); 754 return emission; 755 } 756 757 // Otherwise, tell the initialization code that we're in this case. 758 emission.IsConstantAggregate = true; 759 } 760 761 // A normal fixed sized variable becomes an alloca in the entry block, 762 // unless it's an NRVO variable. 763 llvm::Type *LTy = ConvertTypeForMem(Ty); 764 765 if (NRVO) { 766 // The named return value optimization: allocate this variable in the 767 // return slot, so that we can elide the copy when returning this 768 // variable (C++0x [class.copy]p34). 769 DeclPtr = ReturnValue; 770 771 if (const RecordType *RecordTy = Ty->getAs<RecordType>()) { 772 if (!cast<CXXRecordDecl>(RecordTy->getDecl())->hasTrivialDestructor()) { 773 // Create a flag that is used to indicate when the NRVO was applied 774 // to this variable. Set it to zero to indicate that NRVO was not 775 // applied. 776 llvm::Value *Zero = Builder.getFalse(); 777 llvm::Value *NRVOFlag = CreateTempAlloca(Zero->getType(), "nrvo"); 778 EnsureInsertPoint(); 779 Builder.CreateStore(Zero, NRVOFlag); 780 781 // Record the NRVO flag for this variable. 782 NRVOFlags[&D] = NRVOFlag; 783 emission.NRVOFlag = NRVOFlag; 784 } 785 } 786 } else { 787 if (isByRef) 788 LTy = BuildByRefType(&D); 789 790 llvm::AllocaInst *Alloc = CreateTempAlloca(LTy); 791 Alloc->setName(D.getNameAsString()); 792 793 CharUnits allocaAlignment = alignment; 794 if (isByRef) 795 allocaAlignment = std::max(allocaAlignment, 796 getContext().toCharUnitsFromBits(Target.getPointerAlign(0))); 797 Alloc->setAlignment(allocaAlignment.getQuantity()); 798 DeclPtr = Alloc; 799 } 800 } else { 801 // Targets that don't support recursion emit locals as globals. 802 const char *Class = 803 D.getStorageClass() == SC_Register ? ".reg." : ".auto."; 804 DeclPtr = CreateStaticVarDecl(D, Class, 805 llvm::GlobalValue::InternalLinkage); 806 } 807 } else { 808 EnsureInsertPoint(); 809 810 if (!DidCallStackSave) { 811 // Save the stack. 812 llvm::Value *Stack = CreateTempAlloca(Int8PtrTy, "saved_stack"); 813 814 llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave); 815 llvm::Value *V = Builder.CreateCall(F); 816 817 Builder.CreateStore(V, Stack); 818 819 DidCallStackSave = true; 820 821 // Push a cleanup block and restore the stack there. 822 // FIXME: in general circumstances, this should be an EH cleanup. 823 EHStack.pushCleanup<CallStackRestore>(NormalCleanup, Stack); 824 } 825 826 llvm::Value *elementCount; 827 QualType elementType; 828 llvm::tie(elementCount, elementType) = getVLASize(Ty); 829 830 llvm::Type *llvmTy = ConvertTypeForMem(elementType); 831 832 // Allocate memory for the array. 833 llvm::AllocaInst *vla = Builder.CreateAlloca(llvmTy, elementCount, "vla"); 834 vla->setAlignment(alignment.getQuantity()); 835 836 DeclPtr = vla; 837 } 838 839 llvm::Value *&DMEntry = LocalDeclMap[&D]; 840 assert(DMEntry == 0 && "Decl already exists in localdeclmap!"); 841 DMEntry = DeclPtr; 842 emission.Address = DeclPtr; 843 844 // Emit debug info for local var declaration. 845 if (HaveInsertPoint()) 846 if (CGDebugInfo *DI = getDebugInfo()) { 847 DI->setLocation(D.getLocation()); 848 if (Target.useGlobalsForAutomaticVariables()) { 849 DI->EmitGlobalVariable(static_cast<llvm::GlobalVariable *>(DeclPtr), &D); 850 } else 851 DI->EmitDeclareOfAutoVariable(&D, DeclPtr, Builder); 852 } 853 854 if (D.hasAttr<AnnotateAttr>()) 855 EmitVarAnnotations(&D, emission.Address); 856 857 return emission; 858 } 859 860 /// Determines whether the given __block variable is potentially 861 /// captured by the given expression. 862 static bool isCapturedBy(const VarDecl &var, const Expr *e) { 863 // Skip the most common kinds of expressions that make 864 // hierarchy-walking expensive. 865 e = e->IgnoreParenCasts(); 866 867 if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) { 868 const BlockDecl *block = be->getBlockDecl(); 869 for (BlockDecl::capture_const_iterator i = block->capture_begin(), 870 e = block->capture_end(); i != e; ++i) { 871 if (i->getVariable() == &var) 872 return true; 873 } 874 875 // No need to walk into the subexpressions. 876 return false; 877 } 878 879 if (const StmtExpr *SE = dyn_cast<StmtExpr>(e)) { 880 const CompoundStmt *CS = SE->getSubStmt(); 881 for (CompoundStmt::const_body_iterator BI = CS->body_begin(), 882 BE = CS->body_end(); BI != BE; ++BI) 883 if (Expr *E = dyn_cast<Expr>((*BI))) { 884 if (isCapturedBy(var, E)) 885 return true; 886 } 887 else if (DeclStmt *DS = dyn_cast<DeclStmt>((*BI))) { 888 // special case declarations 889 for (DeclStmt::decl_iterator I = DS->decl_begin(), E = DS->decl_end(); 890 I != E; ++I) { 891 if (VarDecl *VD = dyn_cast<VarDecl>((*I))) { 892 Expr *Init = VD->getInit(); 893 if (Init && isCapturedBy(var, Init)) 894 return true; 895 } 896 } 897 } 898 else 899 // FIXME. Make safe assumption assuming arbitrary statements cause capturing. 900 // Later, provide code to poke into statements for capture analysis. 901 return true; 902 return false; 903 } 904 905 for (Stmt::const_child_range children = e->children(); children; ++children) 906 if (isCapturedBy(var, cast<Expr>(*children))) 907 return true; 908 909 return false; 910 } 911 912 /// \brief Determine whether the given initializer is trivial in the sense 913 /// that it requires no code to be generated. 914 static bool isTrivialInitializer(const Expr *Init) { 915 if (!Init) 916 return true; 917 918 if (const CXXConstructExpr *Construct = dyn_cast<CXXConstructExpr>(Init)) 919 if (CXXConstructorDecl *Constructor = Construct->getConstructor()) 920 if (Constructor->isTrivial() && 921 Constructor->isDefaultConstructor() && 922 !Construct->requiresZeroInitialization()) 923 return true; 924 925 return false; 926 } 927 void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) { 928 assert(emission.Variable && "emission was not valid!"); 929 930 // If this was emitted as a global constant, we're done. 931 if (emission.wasEmittedAsGlobal()) return; 932 933 const VarDecl &D = *emission.Variable; 934 QualType type = D.getType(); 935 936 // If this local has an initializer, emit it now. 937 const Expr *Init = D.getInit(); 938 939 // If we are at an unreachable point, we don't need to emit the initializer 940 // unless it contains a label. 941 if (!HaveInsertPoint()) { 942 if (!Init || !ContainsLabel(Init)) return; 943 EnsureInsertPoint(); 944 } 945 946 // Initialize the structure of a __block variable. 947 if (emission.IsByRef) 948 emitByrefStructureInit(emission); 949 950 if (isTrivialInitializer(Init)) 951 return; 952 953 CharUnits alignment = emission.Alignment; 954 955 // Check whether this is a byref variable that's potentially 956 // captured and moved by its own initializer. If so, we'll need to 957 // emit the initializer first, then copy into the variable. 958 bool capturedByInit = emission.IsByRef && isCapturedBy(D, Init); 959 960 llvm::Value *Loc = 961 capturedByInit ? emission.Address : emission.getObjectAddress(*this); 962 963 if (!emission.IsConstantAggregate) { 964 LValue lv = MakeAddrLValue(Loc, type, alignment.getQuantity()); 965 lv.setNonGC(true); 966 return EmitExprAsInit(Init, &D, lv, capturedByInit); 967 } 968 969 // If this is a simple aggregate initialization, we can optimize it 970 // in various ways. 971 assert(!capturedByInit && "constant init contains a capturing block?"); 972 973 bool isVolatile = type.isVolatileQualified(); 974 975 llvm::Constant *constant = CGM.EmitConstantExpr(D.getInit(), type, this); 976 assert(constant != 0 && "Wasn't a simple constant init?"); 977 978 llvm::Value *SizeVal = 979 llvm::ConstantInt::get(IntPtrTy, 980 getContext().getTypeSizeInChars(type).getQuantity()); 981 982 llvm::Type *BP = Int8PtrTy; 983 if (Loc->getType() != BP) 984 Loc = Builder.CreateBitCast(Loc, BP); 985 986 // If the initializer is all or mostly zeros, codegen with memset then do 987 // a few stores afterward. 988 if (shouldUseMemSetPlusStoresToInitialize(constant, 989 CGM.getTargetData().getTypeAllocSize(constant->getType()))) { 990 Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, 0), SizeVal, 991 alignment.getQuantity(), isVolatile); 992 if (!constant->isNullValue()) { 993 Loc = Builder.CreateBitCast(Loc, constant->getType()->getPointerTo()); 994 emitStoresForInitAfterMemset(constant, Loc, isVolatile, Builder); 995 } 996 } else { 997 // Otherwise, create a temporary global with the initializer then 998 // memcpy from the global to the alloca. 999 std::string Name = GetStaticDeclName(*this, D, "."); 1000 llvm::GlobalVariable *GV = 1001 new llvm::GlobalVariable(CGM.getModule(), constant->getType(), true, 1002 llvm::GlobalValue::PrivateLinkage, 1003 constant, Name, 0, false, 0); 1004 GV->setAlignment(alignment.getQuantity()); 1005 GV->setUnnamedAddr(true); 1006 1007 llvm::Value *SrcPtr = GV; 1008 if (SrcPtr->getType() != BP) 1009 SrcPtr = Builder.CreateBitCast(SrcPtr, BP); 1010 1011 Builder.CreateMemCpy(Loc, SrcPtr, SizeVal, alignment.getQuantity(), 1012 isVolatile); 1013 } 1014 } 1015 1016 /// Emit an expression as an initializer for a variable at the given 1017 /// location. The expression is not necessarily the normal 1018 /// initializer for the variable, and the address is not necessarily 1019 /// its normal location. 1020 /// 1021 /// \param init the initializing expression 1022 /// \param var the variable to act as if we're initializing 1023 /// \param loc the address to initialize; its type is a pointer 1024 /// to the LLVM mapping of the variable's type 1025 /// \param alignment the alignment of the address 1026 /// \param capturedByInit true if the variable is a __block variable 1027 /// whose address is potentially changed by the initializer 1028 void CodeGenFunction::EmitExprAsInit(const Expr *init, 1029 const ValueDecl *D, 1030 LValue lvalue, 1031 bool capturedByInit) { 1032 QualType type = D->getType(); 1033 1034 if (type->isReferenceType()) { 1035 RValue rvalue = EmitReferenceBindingToExpr(init, D); 1036 if (capturedByInit) 1037 drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 1038 EmitStoreThroughLValue(rvalue, lvalue); 1039 } else if (!hasAggregateLLVMType(type)) { 1040 EmitScalarInit(init, D, lvalue, capturedByInit); 1041 } else if (type->isAnyComplexType()) { 1042 ComplexPairTy complex = EmitComplexExpr(init); 1043 if (capturedByInit) 1044 drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 1045 StoreComplexToAddr(complex, lvalue.getAddress(), lvalue.isVolatile()); 1046 } else { 1047 // TODO: how can we delay here if D is captured by its initializer? 1048 EmitAggExpr(init, AggValueSlot::forLValue(lvalue, 1049 AggValueSlot::IsDestructed, 1050 AggValueSlot::DoesNotNeedGCBarriers, 1051 AggValueSlot::IsNotAliased)); 1052 } 1053 } 1054 1055 /// Enter a destroy cleanup for the given local variable. 1056 void CodeGenFunction::emitAutoVarTypeCleanup( 1057 const CodeGenFunction::AutoVarEmission &emission, 1058 QualType::DestructionKind dtorKind) { 1059 assert(dtorKind != QualType::DK_none); 1060 1061 // Note that for __block variables, we want to destroy the 1062 // original stack object, not the possibly forwarded object. 1063 llvm::Value *addr = emission.getObjectAddress(*this); 1064 1065 const VarDecl *var = emission.Variable; 1066 QualType type = var->getType(); 1067 1068 CleanupKind cleanupKind = NormalAndEHCleanup; 1069 CodeGenFunction::Destroyer *destroyer = 0; 1070 1071 switch (dtorKind) { 1072 case QualType::DK_none: 1073 llvm_unreachable("no cleanup for trivially-destructible variable"); 1074 1075 case QualType::DK_cxx_destructor: 1076 // If there's an NRVO flag on the emission, we need a different 1077 // cleanup. 1078 if (emission.NRVOFlag) { 1079 assert(!type->isArrayType()); 1080 CXXDestructorDecl *dtor = type->getAsCXXRecordDecl()->getDestructor(); 1081 EHStack.pushCleanup<DestroyNRVOVariable>(cleanupKind, addr, dtor, 1082 emission.NRVOFlag); 1083 return; 1084 } 1085 break; 1086 1087 case QualType::DK_objc_strong_lifetime: 1088 // Suppress cleanups for pseudo-strong variables. 1089 if (var->isARCPseudoStrong()) return; 1090 1091 // Otherwise, consider whether to use an EH cleanup or not. 1092 cleanupKind = getARCCleanupKind(); 1093 1094 // Use the imprecise destroyer by default. 1095 if (!var->hasAttr<ObjCPreciseLifetimeAttr>()) 1096 destroyer = CodeGenFunction::destroyARCStrongImprecise; 1097 break; 1098 1099 case QualType::DK_objc_weak_lifetime: 1100 break; 1101 } 1102 1103 // If we haven't chosen a more specific destroyer, use the default. 1104 if (!destroyer) destroyer = &getDestroyer(dtorKind); 1105 1106 // Use an EH cleanup in array destructors iff the destructor itself 1107 // is being pushed as an EH cleanup. 1108 bool useEHCleanup = (cleanupKind & EHCleanup); 1109 EHStack.pushCleanup<DestroyObject>(cleanupKind, addr, type, destroyer, 1110 useEHCleanup); 1111 } 1112 1113 void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) { 1114 assert(emission.Variable && "emission was not valid!"); 1115 1116 // If this was emitted as a global constant, we're done. 1117 if (emission.wasEmittedAsGlobal()) return; 1118 1119 const VarDecl &D = *emission.Variable; 1120 1121 // Check the type for a cleanup. 1122 if (QualType::DestructionKind dtorKind = D.getType().isDestructedType()) 1123 emitAutoVarTypeCleanup(emission, dtorKind); 1124 1125 // In GC mode, honor objc_precise_lifetime. 1126 if (getLangOptions().getGC() != LangOptions::NonGC && 1127 D.hasAttr<ObjCPreciseLifetimeAttr>()) { 1128 EHStack.pushCleanup<ExtendGCLifetime>(NormalCleanup, &D); 1129 } 1130 1131 // Handle the cleanup attribute. 1132 if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) { 1133 const FunctionDecl *FD = CA->getFunctionDecl(); 1134 1135 llvm::Constant *F = CGM.GetAddrOfFunction(FD); 1136 assert(F && "Could not find function!"); 1137 1138 const CGFunctionInfo &Info = CGM.getTypes().getFunctionInfo(FD); 1139 EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup, F, &Info, &D); 1140 } 1141 1142 // If this is a block variable, call _Block_object_destroy 1143 // (on the unforwarded address). 1144 if (emission.IsByRef) 1145 enterByrefCleanup(emission); 1146 } 1147 1148 CodeGenFunction::Destroyer & 1149 CodeGenFunction::getDestroyer(QualType::DestructionKind kind) { 1150 // This is surprisingly compiler-dependent. GCC 4.2 can't bind 1151 // references to functions directly in returns, and using '*&foo' 1152 // confuses MSVC. Luckily, the following code pattern works in both. 1153 Destroyer *destroyer = 0; 1154 switch (kind) { 1155 case QualType::DK_none: llvm_unreachable("no destroyer for trivial dtor"); 1156 case QualType::DK_cxx_destructor: 1157 destroyer = &destroyCXXObject; 1158 break; 1159 case QualType::DK_objc_strong_lifetime: 1160 destroyer = &destroyARCStrongPrecise; 1161 break; 1162 case QualType::DK_objc_weak_lifetime: 1163 destroyer = &destroyARCWeak; 1164 break; 1165 } 1166 return *destroyer; 1167 } 1168 1169 /// pushDestroy - Push the standard destructor for the given type. 1170 void CodeGenFunction::pushDestroy(QualType::DestructionKind dtorKind, 1171 llvm::Value *addr, QualType type) { 1172 assert(dtorKind && "cannot push destructor for trivial type"); 1173 1174 CleanupKind cleanupKind = getCleanupKind(dtorKind); 1175 pushDestroy(cleanupKind, addr, type, getDestroyer(dtorKind), 1176 cleanupKind & EHCleanup); 1177 } 1178 1179 void CodeGenFunction::pushDestroy(CleanupKind cleanupKind, llvm::Value *addr, 1180 QualType type, Destroyer &destroyer, 1181 bool useEHCleanupForArray) { 1182 pushFullExprCleanup<DestroyObject>(cleanupKind, addr, type, 1183 destroyer, useEHCleanupForArray); 1184 } 1185 1186 /// emitDestroy - Immediately perform the destruction of the given 1187 /// object. 1188 /// 1189 /// \param addr - the address of the object; a type* 1190 /// \param type - the type of the object; if an array type, all 1191 /// objects are destroyed in reverse order 1192 /// \param destroyer - the function to call to destroy individual 1193 /// elements 1194 /// \param useEHCleanupForArray - whether an EH cleanup should be 1195 /// used when destroying array elements, in case one of the 1196 /// destructions throws an exception 1197 void CodeGenFunction::emitDestroy(llvm::Value *addr, QualType type, 1198 Destroyer &destroyer, 1199 bool useEHCleanupForArray) { 1200 const ArrayType *arrayType = getContext().getAsArrayType(type); 1201 if (!arrayType) 1202 return destroyer(*this, addr, type); 1203 1204 llvm::Value *begin = addr; 1205 llvm::Value *length = emitArrayLength(arrayType, type, begin); 1206 1207 // Normally we have to check whether the array is zero-length. 1208 bool checkZeroLength = true; 1209 1210 // But if the array length is constant, we can suppress that. 1211 if (llvm::ConstantInt *constLength = dyn_cast<llvm::ConstantInt>(length)) { 1212 // ...and if it's constant zero, we can just skip the entire thing. 1213 if (constLength->isZero()) return; 1214 checkZeroLength = false; 1215 } 1216 1217 llvm::Value *end = Builder.CreateInBoundsGEP(begin, length); 1218 emitArrayDestroy(begin, end, type, destroyer, 1219 checkZeroLength, useEHCleanupForArray); 1220 } 1221 1222 /// emitArrayDestroy - Destroys all the elements of the given array, 1223 /// beginning from last to first. The array cannot be zero-length. 1224 /// 1225 /// \param begin - a type* denoting the first element of the array 1226 /// \param end - a type* denoting one past the end of the array 1227 /// \param type - the element type of the array 1228 /// \param destroyer - the function to call to destroy elements 1229 /// \param useEHCleanup - whether to push an EH cleanup to destroy 1230 /// the remaining elements in case the destruction of a single 1231 /// element throws 1232 void CodeGenFunction::emitArrayDestroy(llvm::Value *begin, 1233 llvm::Value *end, 1234 QualType type, 1235 Destroyer &destroyer, 1236 bool checkZeroLength, 1237 bool useEHCleanup) { 1238 assert(!type->isArrayType()); 1239 1240 // The basic structure here is a do-while loop, because we don't 1241 // need to check for the zero-element case. 1242 llvm::BasicBlock *bodyBB = createBasicBlock("arraydestroy.body"); 1243 llvm::BasicBlock *doneBB = createBasicBlock("arraydestroy.done"); 1244 1245 if (checkZeroLength) { 1246 llvm::Value *isEmpty = Builder.CreateICmpEQ(begin, end, 1247 "arraydestroy.isempty"); 1248 Builder.CreateCondBr(isEmpty, doneBB, bodyBB); 1249 } 1250 1251 // Enter the loop body, making that address the current address. 1252 llvm::BasicBlock *entryBB = Builder.GetInsertBlock(); 1253 EmitBlock(bodyBB); 1254 llvm::PHINode *elementPast = 1255 Builder.CreatePHI(begin->getType(), 2, "arraydestroy.elementPast"); 1256 elementPast->addIncoming(end, entryBB); 1257 1258 // Shift the address back by one element. 1259 llvm::Value *negativeOne = llvm::ConstantInt::get(SizeTy, -1, true); 1260 llvm::Value *element = Builder.CreateInBoundsGEP(elementPast, negativeOne, 1261 "arraydestroy.element"); 1262 1263 if (useEHCleanup) 1264 pushRegularPartialArrayCleanup(begin, element, type, destroyer); 1265 1266 // Perform the actual destruction there. 1267 destroyer(*this, element, type); 1268 1269 if (useEHCleanup) 1270 PopCleanupBlock(); 1271 1272 // Check whether we've reached the end. 1273 llvm::Value *done = Builder.CreateICmpEQ(element, begin, "arraydestroy.done"); 1274 Builder.CreateCondBr(done, doneBB, bodyBB); 1275 elementPast->addIncoming(element, Builder.GetInsertBlock()); 1276 1277 // Done. 1278 EmitBlock(doneBB); 1279 } 1280 1281 /// Perform partial array destruction as if in an EH cleanup. Unlike 1282 /// emitArrayDestroy, the element type here may still be an array type. 1283 static void emitPartialArrayDestroy(CodeGenFunction &CGF, 1284 llvm::Value *begin, llvm::Value *end, 1285 QualType type, 1286 CodeGenFunction::Destroyer &destroyer) { 1287 // If the element type is itself an array, drill down. 1288 unsigned arrayDepth = 0; 1289 while (const ArrayType *arrayType = CGF.getContext().getAsArrayType(type)) { 1290 // VLAs don't require a GEP index to walk into. 1291 if (!isa<VariableArrayType>(arrayType)) 1292 arrayDepth++; 1293 type = arrayType->getElementType(); 1294 } 1295 1296 if (arrayDepth) { 1297 llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, arrayDepth+1); 1298 1299 SmallVector<llvm::Value*,4> gepIndices(arrayDepth, zero); 1300 begin = CGF.Builder.CreateInBoundsGEP(begin, gepIndices, "pad.arraybegin"); 1301 end = CGF.Builder.CreateInBoundsGEP(end, gepIndices, "pad.arrayend"); 1302 } 1303 1304 // Destroy the array. We don't ever need an EH cleanup because we 1305 // assume that we're in an EH cleanup ourselves, so a throwing 1306 // destructor causes an immediate terminate. 1307 CGF.emitArrayDestroy(begin, end, type, destroyer, 1308 /*checkZeroLength*/ true, /*useEHCleanup*/ false); 1309 } 1310 1311 namespace { 1312 /// RegularPartialArrayDestroy - a cleanup which performs a partial 1313 /// array destroy where the end pointer is regularly determined and 1314 /// does not need to be loaded from a local. 1315 class RegularPartialArrayDestroy : public EHScopeStack::Cleanup { 1316 llvm::Value *ArrayBegin; 1317 llvm::Value *ArrayEnd; 1318 QualType ElementType; 1319 CodeGenFunction::Destroyer &Destroyer; 1320 public: 1321 RegularPartialArrayDestroy(llvm::Value *arrayBegin, llvm::Value *arrayEnd, 1322 QualType elementType, 1323 CodeGenFunction::Destroyer *destroyer) 1324 : ArrayBegin(arrayBegin), ArrayEnd(arrayEnd), 1325 ElementType(elementType), Destroyer(*destroyer) {} 1326 1327 void Emit(CodeGenFunction &CGF, Flags flags) { 1328 emitPartialArrayDestroy(CGF, ArrayBegin, ArrayEnd, 1329 ElementType, Destroyer); 1330 } 1331 }; 1332 1333 /// IrregularPartialArrayDestroy - a cleanup which performs a 1334 /// partial array destroy where the end pointer is irregularly 1335 /// determined and must be loaded from a local. 1336 class IrregularPartialArrayDestroy : public EHScopeStack::Cleanup { 1337 llvm::Value *ArrayBegin; 1338 llvm::Value *ArrayEndPointer; 1339 QualType ElementType; 1340 CodeGenFunction::Destroyer &Destroyer; 1341 public: 1342 IrregularPartialArrayDestroy(llvm::Value *arrayBegin, 1343 llvm::Value *arrayEndPointer, 1344 QualType elementType, 1345 CodeGenFunction::Destroyer *destroyer) 1346 : ArrayBegin(arrayBegin), ArrayEndPointer(arrayEndPointer), 1347 ElementType(elementType), Destroyer(*destroyer) {} 1348 1349 void Emit(CodeGenFunction &CGF, Flags flags) { 1350 llvm::Value *arrayEnd = CGF.Builder.CreateLoad(ArrayEndPointer); 1351 emitPartialArrayDestroy(CGF, ArrayBegin, arrayEnd, 1352 ElementType, Destroyer); 1353 } 1354 }; 1355 } 1356 1357 /// pushIrregularPartialArrayCleanup - Push an EH cleanup to destroy 1358 /// already-constructed elements of the given array. The cleanup 1359 /// may be popped with DeactivateCleanupBlock or PopCleanupBlock. 1360 /// 1361 /// \param elementType - the immediate element type of the array; 1362 /// possibly still an array type 1363 /// \param array - a value of type elementType* 1364 /// \param destructionKind - the kind of destruction required 1365 /// \param initializedElementCount - a value of type size_t* holding 1366 /// the number of successfully-constructed elements 1367 void CodeGenFunction::pushIrregularPartialArrayCleanup(llvm::Value *arrayBegin, 1368 llvm::Value *arrayEndPointer, 1369 QualType elementType, 1370 Destroyer &destroyer) { 1371 pushFullExprCleanup<IrregularPartialArrayDestroy>(EHCleanup, 1372 arrayBegin, arrayEndPointer, 1373 elementType, &destroyer); 1374 } 1375 1376 /// pushRegularPartialArrayCleanup - Push an EH cleanup to destroy 1377 /// already-constructed elements of the given array. The cleanup 1378 /// may be popped with DeactivateCleanupBlock or PopCleanupBlock. 1379 /// 1380 /// \param elementType - the immediate element type of the array; 1381 /// possibly still an array type 1382 /// \param array - a value of type elementType* 1383 /// \param destructionKind - the kind of destruction required 1384 /// \param initializedElementCount - a value of type size_t* holding 1385 /// the number of successfully-constructed elements 1386 void CodeGenFunction::pushRegularPartialArrayCleanup(llvm::Value *arrayBegin, 1387 llvm::Value *arrayEnd, 1388 QualType elementType, 1389 Destroyer &destroyer) { 1390 pushFullExprCleanup<RegularPartialArrayDestroy>(EHCleanup, 1391 arrayBegin, arrayEnd, 1392 elementType, &destroyer); 1393 } 1394 1395 namespace { 1396 /// A cleanup to perform a release of an object at the end of a 1397 /// function. This is used to balance out the incoming +1 of a 1398 /// ns_consumed argument when we can't reasonably do that just by 1399 /// not doing the initial retain for a __block argument. 1400 struct ConsumeARCParameter : EHScopeStack::Cleanup { 1401 ConsumeARCParameter(llvm::Value *param) : Param(param) {} 1402 1403 llvm::Value *Param; 1404 1405 void Emit(CodeGenFunction &CGF, Flags flags) { 1406 CGF.EmitARCRelease(Param, /*precise*/ false); 1407 } 1408 }; 1409 } 1410 1411 /// Emit an alloca (or GlobalValue depending on target) 1412 /// for the specified parameter and set up LocalDeclMap. 1413 void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg, 1414 unsigned ArgNo) { 1415 // FIXME: Why isn't ImplicitParamDecl a ParmVarDecl? 1416 assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) && 1417 "Invalid argument to EmitParmDecl"); 1418 1419 Arg->setName(D.getName()); 1420 1421 // Use better IR generation for certain implicit parameters. 1422 if (isa<ImplicitParamDecl>(D)) { 1423 // The only implicit argument a block has is its literal. 1424 if (BlockInfo) { 1425 LocalDeclMap[&D] = Arg; 1426 1427 if (CGDebugInfo *DI = getDebugInfo()) { 1428 DI->setLocation(D.getLocation()); 1429 DI->EmitDeclareOfBlockLiteralArgVariable(*BlockInfo, Arg, Builder); 1430 } 1431 1432 return; 1433 } 1434 } 1435 1436 QualType Ty = D.getType(); 1437 1438 llvm::Value *DeclPtr; 1439 // If this is an aggregate or variable sized value, reuse the input pointer. 1440 if (!Ty->isConstantSizeType() || 1441 CodeGenFunction::hasAggregateLLVMType(Ty)) { 1442 DeclPtr = Arg; 1443 } else { 1444 // Otherwise, create a temporary to hold the value. 1445 DeclPtr = CreateMemTemp(Ty, D.getName() + ".addr"); 1446 1447 bool doStore = true; 1448 1449 Qualifiers qs = Ty.getQualifiers(); 1450 1451 if (Qualifiers::ObjCLifetime lt = qs.getObjCLifetime()) { 1452 // We honor __attribute__((ns_consumed)) for types with lifetime. 1453 // For __strong, it's handled by just skipping the initial retain; 1454 // otherwise we have to balance out the initial +1 with an extra 1455 // cleanup to do the release at the end of the function. 1456 bool isConsumed = D.hasAttr<NSConsumedAttr>(); 1457 1458 // 'self' is always formally __strong, but if this is not an 1459 // init method then we don't want to retain it. 1460 if (D.isARCPseudoStrong()) { 1461 const ObjCMethodDecl *method = cast<ObjCMethodDecl>(CurCodeDecl); 1462 assert(&D == method->getSelfDecl()); 1463 assert(lt == Qualifiers::OCL_Strong); 1464 assert(qs.hasConst()); 1465 assert(method->getMethodFamily() != OMF_init); 1466 (void) method; 1467 lt = Qualifiers::OCL_ExplicitNone; 1468 } 1469 1470 if (lt == Qualifiers::OCL_Strong) { 1471 if (!isConsumed) 1472 // Don't use objc_retainBlock for block pointers, because we 1473 // don't want to Block_copy something just because we got it 1474 // as a parameter. 1475 Arg = EmitARCRetainNonBlock(Arg); 1476 } else { 1477 // Push the cleanup for a consumed parameter. 1478 if (isConsumed) 1479 EHStack.pushCleanup<ConsumeARCParameter>(getARCCleanupKind(), Arg); 1480 1481 if (lt == Qualifiers::OCL_Weak) { 1482 EmitARCInitWeak(DeclPtr, Arg); 1483 doStore = false; // The weak init is a store, no need to do two 1484 } 1485 } 1486 1487 // Enter the cleanup scope. 1488 EmitAutoVarWithLifetime(*this, D, DeclPtr, lt); 1489 } 1490 1491 // Store the initial value into the alloca. 1492 if (doStore) { 1493 LValue lv = MakeAddrLValue(DeclPtr, Ty, 1494 getContext().getDeclAlign(&D).getQuantity()); 1495 EmitStoreOfScalar(Arg, lv); 1496 } 1497 } 1498 1499 llvm::Value *&DMEntry = LocalDeclMap[&D]; 1500 assert(DMEntry == 0 && "Decl already exists in localdeclmap!"); 1501 DMEntry = DeclPtr; 1502 1503 // Emit debug info for param declaration. 1504 if (CGDebugInfo *DI = getDebugInfo()) 1505 DI->EmitDeclareOfArgVariable(&D, DeclPtr, ArgNo, Builder); 1506 1507 if (D.hasAttr<AnnotateAttr>()) 1508 EmitVarAnnotations(&D, DeclPtr); 1509 } 1510