CGDecl.cpp revision 249423
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::IndirectField: 49 case Decl::ObjCIvar: 50 case Decl::ObjCAtDefsField: 51 case Decl::ParmVar: 52 case Decl::ImplicitParam: 53 case Decl::ClassTemplate: 54 case Decl::FunctionTemplate: 55 case Decl::TypeAliasTemplate: 56 case Decl::TemplateTemplateParm: 57 case Decl::ObjCMethod: 58 case Decl::ObjCCategory: 59 case Decl::ObjCProtocol: 60 case Decl::ObjCInterface: 61 case Decl::ObjCCategoryImpl: 62 case Decl::ObjCImplementation: 63 case Decl::ObjCProperty: 64 case Decl::ObjCCompatibleAlias: 65 case Decl::AccessSpec: 66 case Decl::LinkageSpec: 67 case Decl::ObjCPropertyImpl: 68 case Decl::FileScopeAsm: 69 case Decl::Friend: 70 case Decl::FriendTemplate: 71 case Decl::Block: 72 case Decl::ClassScopeFunctionSpecialization: 73 llvm_unreachable("Declaration should not be in declstmts!"); 74 case Decl::Function: // void X(); 75 case Decl::Record: // struct/union/class X; 76 case Decl::Enum: // enum X; 77 case Decl::EnumConstant: // enum ? { X = ? } 78 case Decl::CXXRecord: // struct/union/class X; [C++] 79 case Decl::Using: // using X; [C++] 80 case Decl::UsingShadow: 81 case Decl::UsingDirective: // using namespace X; [C++] 82 case Decl::NamespaceAlias: 83 case Decl::StaticAssert: // static_assert(X, ""); [C++0x] 84 case Decl::Label: // __label__ x; 85 case Decl::Import: 86 case Decl::OMPThreadPrivate: 87 case Decl::Empty: 88 // None of these decls require codegen support. 89 return; 90 91 case Decl::Var: { 92 const VarDecl &VD = cast<VarDecl>(D); 93 assert(VD.isLocalVarDecl() && 94 "Should not see file-scope variables inside a function!"); 95 return EmitVarDecl(VD); 96 } 97 98 case Decl::Typedef: // typedef int X; 99 case Decl::TypeAlias: { // using X = int; [C++0x] 100 const TypedefNameDecl &TD = cast<TypedefNameDecl>(D); 101 QualType Ty = TD.getUnderlyingType(); 102 103 if (Ty->isVariablyModifiedType()) 104 EmitVariablyModifiedType(Ty); 105 } 106 } 107} 108 109/// EmitVarDecl - This method handles emission of any variable declaration 110/// inside a function, including static vars etc. 111void CodeGenFunction::EmitVarDecl(const VarDecl &D) { 112 switch (D.getStorageClass()) { 113 case SC_None: 114 case SC_Auto: 115 case SC_Register: 116 return EmitAutoVarDecl(D); 117 case SC_Static: { 118 llvm::GlobalValue::LinkageTypes Linkage = 119 llvm::GlobalValue::InternalLinkage; 120 121 // If the function definition has some sort of weak linkage, its 122 // static variables should also be weak so that they get properly 123 // uniqued. We can't do this in C, though, because there's no 124 // standard way to agree on which variables are the same (i.e. 125 // there's no mangling). 126 if (getLangOpts().CPlusPlus) 127 if (llvm::GlobalValue::isWeakForLinker(CurFn->getLinkage())) 128 Linkage = CurFn->getLinkage(); 129 130 return EmitStaticVarDecl(D, Linkage); 131 } 132 case SC_Extern: 133 case SC_PrivateExtern: 134 // Don't emit it now, allow it to be emitted lazily on its first use. 135 return; 136 case SC_OpenCLWorkGroupLocal: 137 return CGM.getOpenCLRuntime().EmitWorkGroupLocalVarDecl(*this, D); 138 } 139 140 llvm_unreachable("Unknown storage class"); 141} 142 143static std::string GetStaticDeclName(CodeGenFunction &CGF, const VarDecl &D, 144 const char *Separator) { 145 CodeGenModule &CGM = CGF.CGM; 146 if (CGF.getLangOpts().CPlusPlus) { 147 StringRef Name = CGM.getMangledName(&D); 148 return Name.str(); 149 } 150 151 std::string ContextName; 152 if (!CGF.CurFuncDecl) { 153 // Better be in a block declared in global scope. 154 const NamedDecl *ND = cast<NamedDecl>(&D); 155 const DeclContext *DC = ND->getDeclContext(); 156 if (const BlockDecl *BD = dyn_cast<BlockDecl>(DC)) { 157 MangleBuffer Name; 158 CGM.getBlockMangledName(GlobalDecl(), Name, BD); 159 ContextName = Name.getString(); 160 } 161 else 162 llvm_unreachable("Unknown context for block static var decl"); 163 } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CGF.CurFuncDecl)) { 164 StringRef Name = CGM.getMangledName(FD); 165 ContextName = Name.str(); 166 } else if (isa<ObjCMethodDecl>(CGF.CurFuncDecl)) 167 ContextName = CGF.CurFn->getName(); 168 else 169 llvm_unreachable("Unknown context for static var decl"); 170 171 return ContextName + Separator + D.getNameAsString(); 172} 173 174llvm::GlobalVariable * 175CodeGenFunction::CreateStaticVarDecl(const VarDecl &D, 176 const char *Separator, 177 llvm::GlobalValue::LinkageTypes Linkage) { 178 QualType Ty = D.getType(); 179 assert(Ty->isConstantSizeType() && "VLAs can't be static"); 180 181 // Use the label if the variable is renamed with the asm-label extension. 182 std::string Name; 183 if (D.hasAttr<AsmLabelAttr>()) 184 Name = CGM.getMangledName(&D); 185 else 186 Name = GetStaticDeclName(*this, D, Separator); 187 188 llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(Ty); 189 unsigned AddrSpace = 190 CGM.GetGlobalVarAddressSpace(&D, CGM.getContext().getTargetAddressSpace(Ty)); 191 llvm::GlobalVariable *GV = 192 new llvm::GlobalVariable(CGM.getModule(), LTy, 193 Ty.isConstant(getContext()), Linkage, 194 CGM.EmitNullConstant(D.getType()), Name, 0, 195 llvm::GlobalVariable::NotThreadLocal, 196 AddrSpace); 197 GV->setAlignment(getContext().getDeclAlign(&D).getQuantity()); 198 if (Linkage != llvm::GlobalValue::InternalLinkage) 199 GV->setVisibility(CurFn->getVisibility()); 200 201 if (D.isThreadSpecified()) 202 CGM.setTLSMode(GV, D); 203 204 return GV; 205} 206 207/// hasNontrivialDestruction - Determine whether a type's destruction is 208/// non-trivial. If so, and the variable uses static initialization, we must 209/// register its destructor to run on exit. 210static bool hasNontrivialDestruction(QualType T) { 211 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl(); 212 return RD && !RD->hasTrivialDestructor(); 213} 214 215/// AddInitializerToStaticVarDecl - Add the initializer for 'D' to the 216/// global variable that has already been created for it. If the initializer 217/// has a different type than GV does, this may free GV and return a different 218/// one. Otherwise it just returns GV. 219llvm::GlobalVariable * 220CodeGenFunction::AddInitializerToStaticVarDecl(const VarDecl &D, 221 llvm::GlobalVariable *GV) { 222 llvm::Constant *Init = CGM.EmitConstantInit(D, this); 223 224 // If constant emission failed, then this should be a C++ static 225 // initializer. 226 if (!Init) { 227 if (!getLangOpts().CPlusPlus) 228 CGM.ErrorUnsupported(D.getInit(), "constant l-value expression"); 229 else if (Builder.GetInsertBlock()) { 230 // Since we have a static initializer, this global variable can't 231 // be constant. 232 GV->setConstant(false); 233 234 EmitCXXGuardedInit(D, GV, /*PerformInit*/true); 235 } 236 return GV; 237 } 238 239 // The initializer may differ in type from the global. Rewrite 240 // the global to match the initializer. (We have to do this 241 // because some types, like unions, can't be completely represented 242 // in the LLVM type system.) 243 if (GV->getType()->getElementType() != Init->getType()) { 244 llvm::GlobalVariable *OldGV = GV; 245 246 GV = new llvm::GlobalVariable(CGM.getModule(), Init->getType(), 247 OldGV->isConstant(), 248 OldGV->getLinkage(), Init, "", 249 /*InsertBefore*/ OldGV, 250 OldGV->getThreadLocalMode(), 251 CGM.getContext().getTargetAddressSpace(D.getType())); 252 GV->setVisibility(OldGV->getVisibility()); 253 254 // Steal the name of the old global 255 GV->takeName(OldGV); 256 257 // Replace all uses of the old global with the new global 258 llvm::Constant *NewPtrForOldDecl = 259 llvm::ConstantExpr::getBitCast(GV, OldGV->getType()); 260 OldGV->replaceAllUsesWith(NewPtrForOldDecl); 261 262 // Erase the old global, since it is no longer used. 263 OldGV->eraseFromParent(); 264 } 265 266 GV->setConstant(CGM.isTypeConstant(D.getType(), true)); 267 GV->setInitializer(Init); 268 269 if (hasNontrivialDestruction(D.getType())) { 270 // We have a constant initializer, but a nontrivial destructor. We still 271 // need to perform a guarded "initialization" in order to register the 272 // destructor. 273 EmitCXXGuardedInit(D, GV, /*PerformInit*/false); 274 } 275 276 return GV; 277} 278 279void CodeGenFunction::EmitStaticVarDecl(const VarDecl &D, 280 llvm::GlobalValue::LinkageTypes Linkage) { 281 llvm::Value *&DMEntry = LocalDeclMap[&D]; 282 assert(DMEntry == 0 && "Decl already exists in localdeclmap!"); 283 284 // Check to see if we already have a global variable for this 285 // declaration. This can happen when double-emitting function 286 // bodies, e.g. with complete and base constructors. 287 llvm::Constant *addr = 288 CGM.getStaticLocalDeclAddress(&D); 289 290 llvm::GlobalVariable *var; 291 if (addr) { 292 var = cast<llvm::GlobalVariable>(addr->stripPointerCasts()); 293 } else { 294 addr = var = CreateStaticVarDecl(D, ".", Linkage); 295 } 296 297 // Store into LocalDeclMap before generating initializer to handle 298 // circular references. 299 DMEntry = addr; 300 CGM.setStaticLocalDeclAddress(&D, addr); 301 302 // We can't have a VLA here, but we can have a pointer to a VLA, 303 // even though that doesn't really make any sense. 304 // Make sure to evaluate VLA bounds now so that we have them for later. 305 if (D.getType()->isVariablyModifiedType()) 306 EmitVariablyModifiedType(D.getType()); 307 308 // Save the type in case adding the initializer forces a type change. 309 llvm::Type *expectedType = addr->getType(); 310 311 // If this value has an initializer, emit it. 312 if (D.getInit()) 313 var = AddInitializerToStaticVarDecl(D, var); 314 315 var->setAlignment(getContext().getDeclAlign(&D).getQuantity()); 316 317 if (D.hasAttr<AnnotateAttr>()) 318 CGM.AddGlobalAnnotations(&D, var); 319 320 if (const SectionAttr *SA = D.getAttr<SectionAttr>()) 321 var->setSection(SA->getName()); 322 323 if (D.hasAttr<UsedAttr>()) 324 CGM.AddUsedGlobal(var); 325 326 // We may have to cast the constant because of the initializer 327 // mismatch above. 328 // 329 // FIXME: It is really dangerous to store this in the map; if anyone 330 // RAUW's the GV uses of this constant will be invalid. 331 llvm::Constant *castedAddr = llvm::ConstantExpr::getBitCast(var, expectedType); 332 DMEntry = castedAddr; 333 CGM.setStaticLocalDeclAddress(&D, castedAddr); 334 335 // Emit global variable debug descriptor for static vars. 336 CGDebugInfo *DI = getDebugInfo(); 337 if (DI && 338 CGM.getCodeGenOpts().getDebugInfo() >= CodeGenOptions::LimitedDebugInfo) { 339 DI->setLocation(D.getLocation()); 340 DI->EmitGlobalVariable(var, &D); 341 } 342} 343 344namespace { 345 struct DestroyObject : EHScopeStack::Cleanup { 346 DestroyObject(llvm::Value *addr, QualType type, 347 CodeGenFunction::Destroyer *destroyer, 348 bool useEHCleanupForArray) 349 : addr(addr), type(type), destroyer(destroyer), 350 useEHCleanupForArray(useEHCleanupForArray) {} 351 352 llvm::Value *addr; 353 QualType type; 354 CodeGenFunction::Destroyer *destroyer; 355 bool useEHCleanupForArray; 356 357 void Emit(CodeGenFunction &CGF, Flags flags) { 358 // Don't use an EH cleanup recursively from an EH cleanup. 359 bool useEHCleanupForArray = 360 flags.isForNormalCleanup() && this->useEHCleanupForArray; 361 362 CGF.emitDestroy(addr, type, destroyer, useEHCleanupForArray); 363 } 364 }; 365 366 struct DestroyNRVOVariable : EHScopeStack::Cleanup { 367 DestroyNRVOVariable(llvm::Value *addr, 368 const CXXDestructorDecl *Dtor, 369 llvm::Value *NRVOFlag) 370 : Dtor(Dtor), NRVOFlag(NRVOFlag), Loc(addr) {} 371 372 const CXXDestructorDecl *Dtor; 373 llvm::Value *NRVOFlag; 374 llvm::Value *Loc; 375 376 void Emit(CodeGenFunction &CGF, Flags flags) { 377 // Along the exceptions path we always execute the dtor. 378 bool NRVO = flags.isForNormalCleanup() && NRVOFlag; 379 380 llvm::BasicBlock *SkipDtorBB = 0; 381 if (NRVO) { 382 // If we exited via NRVO, we skip the destructor call. 383 llvm::BasicBlock *RunDtorBB = CGF.createBasicBlock("nrvo.unused"); 384 SkipDtorBB = CGF.createBasicBlock("nrvo.skipdtor"); 385 llvm::Value *DidNRVO = CGF.Builder.CreateLoad(NRVOFlag, "nrvo.val"); 386 CGF.Builder.CreateCondBr(DidNRVO, SkipDtorBB, RunDtorBB); 387 CGF.EmitBlock(RunDtorBB); 388 } 389 390 CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete, 391 /*ForVirtualBase=*/false, 392 /*Delegating=*/false, 393 Loc); 394 395 if (NRVO) CGF.EmitBlock(SkipDtorBB); 396 } 397 }; 398 399 struct CallStackRestore : EHScopeStack::Cleanup { 400 llvm::Value *Stack; 401 CallStackRestore(llvm::Value *Stack) : Stack(Stack) {} 402 void Emit(CodeGenFunction &CGF, Flags flags) { 403 llvm::Value *V = CGF.Builder.CreateLoad(Stack); 404 llvm::Value *F = CGF.CGM.getIntrinsic(llvm::Intrinsic::stackrestore); 405 CGF.Builder.CreateCall(F, V); 406 } 407 }; 408 409 struct ExtendGCLifetime : EHScopeStack::Cleanup { 410 const VarDecl &Var; 411 ExtendGCLifetime(const VarDecl *var) : Var(*var) {} 412 413 void Emit(CodeGenFunction &CGF, Flags flags) { 414 // Compute the address of the local variable, in case it's a 415 // byref or something. 416 DeclRefExpr DRE(const_cast<VarDecl*>(&Var), false, 417 Var.getType(), VK_LValue, SourceLocation()); 418 llvm::Value *value = CGF.EmitLoadOfScalar(CGF.EmitDeclRefLValue(&DRE)); 419 CGF.EmitExtendGCLifetime(value); 420 } 421 }; 422 423 struct CallCleanupFunction : EHScopeStack::Cleanup { 424 llvm::Constant *CleanupFn; 425 const CGFunctionInfo &FnInfo; 426 const VarDecl &Var; 427 428 CallCleanupFunction(llvm::Constant *CleanupFn, const CGFunctionInfo *Info, 429 const VarDecl *Var) 430 : CleanupFn(CleanupFn), FnInfo(*Info), Var(*Var) {} 431 432 void Emit(CodeGenFunction &CGF, Flags flags) { 433 DeclRefExpr DRE(const_cast<VarDecl*>(&Var), false, 434 Var.getType(), VK_LValue, SourceLocation()); 435 // Compute the address of the local variable, in case it's a byref 436 // or something. 437 llvm::Value *Addr = CGF.EmitDeclRefLValue(&DRE).getAddress(); 438 439 // In some cases, the type of the function argument will be different from 440 // the type of the pointer. An example of this is 441 // void f(void* arg); 442 // __attribute__((cleanup(f))) void *g; 443 // 444 // To fix this we insert a bitcast here. 445 QualType ArgTy = FnInfo.arg_begin()->type; 446 llvm::Value *Arg = 447 CGF.Builder.CreateBitCast(Addr, CGF.ConvertType(ArgTy)); 448 449 CallArgList Args; 450 Args.add(RValue::get(Arg), 451 CGF.getContext().getPointerType(Var.getType())); 452 CGF.EmitCall(FnInfo, CleanupFn, ReturnValueSlot(), Args); 453 } 454 }; 455 456 /// A cleanup to call @llvm.lifetime.end. 457 class CallLifetimeEnd : public EHScopeStack::Cleanup { 458 llvm::Value *Addr; 459 llvm::Value *Size; 460 public: 461 CallLifetimeEnd(llvm::Value *addr, llvm::Value *size) 462 : Addr(addr), Size(size) {} 463 464 void Emit(CodeGenFunction &CGF, Flags flags) { 465 llvm::Value *castAddr = CGF.Builder.CreateBitCast(Addr, CGF.Int8PtrTy); 466 CGF.Builder.CreateCall2(CGF.CGM.getLLVMLifetimeEndFn(), 467 Size, castAddr) 468 ->setDoesNotThrow(); 469 } 470 }; 471} 472 473/// EmitAutoVarWithLifetime - Does the setup required for an automatic 474/// variable with lifetime. 475static void EmitAutoVarWithLifetime(CodeGenFunction &CGF, const VarDecl &var, 476 llvm::Value *addr, 477 Qualifiers::ObjCLifetime lifetime) { 478 switch (lifetime) { 479 case Qualifiers::OCL_None: 480 llvm_unreachable("present but none"); 481 482 case Qualifiers::OCL_ExplicitNone: 483 // nothing to do 484 break; 485 486 case Qualifiers::OCL_Strong: { 487 CodeGenFunction::Destroyer *destroyer = 488 (var.hasAttr<ObjCPreciseLifetimeAttr>() 489 ? CodeGenFunction::destroyARCStrongPrecise 490 : CodeGenFunction::destroyARCStrongImprecise); 491 492 CleanupKind cleanupKind = CGF.getARCCleanupKind(); 493 CGF.pushDestroy(cleanupKind, addr, var.getType(), destroyer, 494 cleanupKind & EHCleanup); 495 break; 496 } 497 case Qualifiers::OCL_Autoreleasing: 498 // nothing to do 499 break; 500 501 case Qualifiers::OCL_Weak: 502 // __weak objects always get EH cleanups; otherwise, exceptions 503 // could cause really nasty crashes instead of mere leaks. 504 CGF.pushDestroy(NormalAndEHCleanup, addr, var.getType(), 505 CodeGenFunction::destroyARCWeak, 506 /*useEHCleanup*/ true); 507 break; 508 } 509} 510 511static bool isAccessedBy(const VarDecl &var, const Stmt *s) { 512 if (const Expr *e = dyn_cast<Expr>(s)) { 513 // Skip the most common kinds of expressions that make 514 // hierarchy-walking expensive. 515 s = e = e->IgnoreParenCasts(); 516 517 if (const DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e)) 518 return (ref->getDecl() == &var); 519 if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) { 520 const BlockDecl *block = be->getBlockDecl(); 521 for (BlockDecl::capture_const_iterator i = block->capture_begin(), 522 e = block->capture_end(); i != e; ++i) { 523 if (i->getVariable() == &var) 524 return true; 525 } 526 } 527 } 528 529 for (Stmt::const_child_range children = s->children(); children; ++children) 530 // children might be null; as in missing decl or conditional of an if-stmt. 531 if ((*children) && isAccessedBy(var, *children)) 532 return true; 533 534 return false; 535} 536 537static bool isAccessedBy(const ValueDecl *decl, const Expr *e) { 538 if (!decl) return false; 539 if (!isa<VarDecl>(decl)) return false; 540 const VarDecl *var = cast<VarDecl>(decl); 541 return isAccessedBy(*var, e); 542} 543 544static void drillIntoBlockVariable(CodeGenFunction &CGF, 545 LValue &lvalue, 546 const VarDecl *var) { 547 lvalue.setAddress(CGF.BuildBlockByrefAddress(lvalue.getAddress(), var)); 548} 549 550void CodeGenFunction::EmitScalarInit(const Expr *init, 551 const ValueDecl *D, 552 LValue lvalue, 553 bool capturedByInit) { 554 Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime(); 555 if (!lifetime) { 556 llvm::Value *value = EmitScalarExpr(init); 557 if (capturedByInit) 558 drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 559 EmitStoreThroughLValue(RValue::get(value), lvalue, true); 560 return; 561 } 562 563 // If we're emitting a value with lifetime, we have to do the 564 // initialization *before* we leave the cleanup scopes. 565 if (const ExprWithCleanups *ewc = dyn_cast<ExprWithCleanups>(init)) { 566 enterFullExpression(ewc); 567 init = ewc->getSubExpr(); 568 } 569 CodeGenFunction::RunCleanupsScope Scope(*this); 570 571 // We have to maintain the illusion that the variable is 572 // zero-initialized. If the variable might be accessed in its 573 // initializer, zero-initialize before running the initializer, then 574 // actually perform the initialization with an assign. 575 bool accessedByInit = false; 576 if (lifetime != Qualifiers::OCL_ExplicitNone) 577 accessedByInit = (capturedByInit || isAccessedBy(D, init)); 578 if (accessedByInit) { 579 LValue tempLV = lvalue; 580 // Drill down to the __block object if necessary. 581 if (capturedByInit) { 582 // We can use a simple GEP for this because it can't have been 583 // moved yet. 584 tempLV.setAddress(Builder.CreateStructGEP(tempLV.getAddress(), 585 getByRefValueLLVMField(cast<VarDecl>(D)))); 586 } 587 588 llvm::PointerType *ty 589 = cast<llvm::PointerType>(tempLV.getAddress()->getType()); 590 ty = cast<llvm::PointerType>(ty->getElementType()); 591 592 llvm::Value *zero = llvm::ConstantPointerNull::get(ty); 593 594 // If __weak, we want to use a barrier under certain conditions. 595 if (lifetime == Qualifiers::OCL_Weak) 596 EmitARCInitWeak(tempLV.getAddress(), zero); 597 598 // Otherwise just do a simple store. 599 else 600 EmitStoreOfScalar(zero, tempLV, /* isInitialization */ true); 601 } 602 603 // Emit the initializer. 604 llvm::Value *value = 0; 605 606 switch (lifetime) { 607 case Qualifiers::OCL_None: 608 llvm_unreachable("present but none"); 609 610 case Qualifiers::OCL_ExplicitNone: 611 // nothing to do 612 value = EmitScalarExpr(init); 613 break; 614 615 case Qualifiers::OCL_Strong: { 616 value = EmitARCRetainScalarExpr(init); 617 break; 618 } 619 620 case Qualifiers::OCL_Weak: { 621 // No way to optimize a producing initializer into this. It's not 622 // worth optimizing for, because the value will immediately 623 // disappear in the common case. 624 value = EmitScalarExpr(init); 625 626 if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 627 if (accessedByInit) 628 EmitARCStoreWeak(lvalue.getAddress(), value, /*ignored*/ true); 629 else 630 EmitARCInitWeak(lvalue.getAddress(), value); 631 return; 632 } 633 634 case Qualifiers::OCL_Autoreleasing: 635 value = EmitARCRetainAutoreleaseScalarExpr(init); 636 break; 637 } 638 639 if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 640 641 // If the variable might have been accessed by its initializer, we 642 // might have to initialize with a barrier. We have to do this for 643 // both __weak and __strong, but __weak got filtered out above. 644 if (accessedByInit && lifetime == Qualifiers::OCL_Strong) { 645 llvm::Value *oldValue = EmitLoadOfScalar(lvalue); 646 EmitStoreOfScalar(value, lvalue, /* isInitialization */ true); 647 EmitARCRelease(oldValue, ARCImpreciseLifetime); 648 return; 649 } 650 651 EmitStoreOfScalar(value, lvalue, /* isInitialization */ true); 652} 653 654/// EmitScalarInit - Initialize the given lvalue with the given object. 655void CodeGenFunction::EmitScalarInit(llvm::Value *init, LValue lvalue) { 656 Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime(); 657 if (!lifetime) 658 return EmitStoreThroughLValue(RValue::get(init), lvalue, true); 659 660 switch (lifetime) { 661 case Qualifiers::OCL_None: 662 llvm_unreachable("present but none"); 663 664 case Qualifiers::OCL_ExplicitNone: 665 // nothing to do 666 break; 667 668 case Qualifiers::OCL_Strong: 669 init = EmitARCRetain(lvalue.getType(), init); 670 break; 671 672 case Qualifiers::OCL_Weak: 673 // Initialize and then skip the primitive store. 674 EmitARCInitWeak(lvalue.getAddress(), init); 675 return; 676 677 case Qualifiers::OCL_Autoreleasing: 678 init = EmitARCRetainAutorelease(lvalue.getType(), init); 679 break; 680 } 681 682 EmitStoreOfScalar(init, lvalue, /* isInitialization */ true); 683} 684 685/// canEmitInitWithFewStoresAfterMemset - Decide whether we can emit the 686/// non-zero parts of the specified initializer with equal or fewer than 687/// NumStores scalar stores. 688static bool canEmitInitWithFewStoresAfterMemset(llvm::Constant *Init, 689 unsigned &NumStores) { 690 // Zero and Undef never requires any extra stores. 691 if (isa<llvm::ConstantAggregateZero>(Init) || 692 isa<llvm::ConstantPointerNull>(Init) || 693 isa<llvm::UndefValue>(Init)) 694 return true; 695 if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) || 696 isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) || 697 isa<llvm::ConstantExpr>(Init)) 698 return Init->isNullValue() || NumStores--; 699 700 // See if we can emit each element. 701 if (isa<llvm::ConstantArray>(Init) || isa<llvm::ConstantStruct>(Init)) { 702 for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) { 703 llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i)); 704 if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores)) 705 return false; 706 } 707 return true; 708 } 709 710 if (llvm::ConstantDataSequential *CDS = 711 dyn_cast<llvm::ConstantDataSequential>(Init)) { 712 for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) { 713 llvm::Constant *Elt = CDS->getElementAsConstant(i); 714 if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores)) 715 return false; 716 } 717 return true; 718 } 719 720 // Anything else is hard and scary. 721 return false; 722} 723 724/// emitStoresForInitAfterMemset - For inits that 725/// canEmitInitWithFewStoresAfterMemset returned true for, emit the scalar 726/// stores that would be required. 727static void emitStoresForInitAfterMemset(llvm::Constant *Init, llvm::Value *Loc, 728 bool isVolatile, CGBuilderTy &Builder) { 729 assert(!Init->isNullValue() && !isa<llvm::UndefValue>(Init) && 730 "called emitStoresForInitAfterMemset for zero or undef value."); 731 732 if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) || 733 isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) || 734 isa<llvm::ConstantExpr>(Init)) { 735 Builder.CreateStore(Init, Loc, isVolatile); 736 return; 737 } 738 739 if (llvm::ConstantDataSequential *CDS = 740 dyn_cast<llvm::ConstantDataSequential>(Init)) { 741 for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) { 742 llvm::Constant *Elt = CDS->getElementAsConstant(i); 743 744 // If necessary, get a pointer to the element and emit it. 745 if (!Elt->isNullValue() && !isa<llvm::UndefValue>(Elt)) 746 emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i), 747 isVolatile, Builder); 748 } 749 return; 750 } 751 752 assert((isa<llvm::ConstantStruct>(Init) || isa<llvm::ConstantArray>(Init)) && 753 "Unknown value type!"); 754 755 for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) { 756 llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i)); 757 758 // If necessary, get a pointer to the element and emit it. 759 if (!Elt->isNullValue() && !isa<llvm::UndefValue>(Elt)) 760 emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i), 761 isVolatile, Builder); 762 } 763} 764 765 766/// shouldUseMemSetPlusStoresToInitialize - Decide whether we should use memset 767/// plus some stores to initialize a local variable instead of using a memcpy 768/// from a constant global. It is beneficial to use memset if the global is all 769/// zeros, or mostly zeros and large. 770static bool shouldUseMemSetPlusStoresToInitialize(llvm::Constant *Init, 771 uint64_t GlobalSize) { 772 // If a global is all zeros, always use a memset. 773 if (isa<llvm::ConstantAggregateZero>(Init)) return true; 774 775 // If a non-zero global is <= 32 bytes, always use a memcpy. If it is large, 776 // do it if it will require 6 or fewer scalar stores. 777 // TODO: Should budget depends on the size? Avoiding a large global warrants 778 // plopping in more stores. 779 unsigned StoreBudget = 6; 780 uint64_t SizeLimit = 32; 781 782 return GlobalSize > SizeLimit && 783 canEmitInitWithFewStoresAfterMemset(Init, StoreBudget); 784} 785 786/// Should we use the LLVM lifetime intrinsics for the given local variable? 787static bool shouldUseLifetimeMarkers(CodeGenFunction &CGF, const VarDecl &D, 788 unsigned Size) { 789 // Always emit lifetime markers in -fsanitize=use-after-scope mode. 790 if (CGF.getLangOpts().Sanitize.UseAfterScope) 791 return true; 792 // For now, only in optimized builds. 793 if (CGF.CGM.getCodeGenOpts().OptimizationLevel == 0) 794 return false; 795 796 // Limit the size of marked objects to 32 bytes. We don't want to increase 797 // compile time by marking tiny objects. 798 unsigned SizeThreshold = 32; 799 800 return Size > SizeThreshold; 801} 802 803 804/// EmitAutoVarDecl - Emit code and set up an entry in LocalDeclMap for a 805/// variable declaration with auto, register, or no storage class specifier. 806/// These turn into simple stack objects, or GlobalValues depending on target. 807void CodeGenFunction::EmitAutoVarDecl(const VarDecl &D) { 808 AutoVarEmission emission = EmitAutoVarAlloca(D); 809 EmitAutoVarInit(emission); 810 EmitAutoVarCleanups(emission); 811} 812 813/// EmitAutoVarAlloca - Emit the alloca and debug information for a 814/// local variable. Does not emit initalization or destruction. 815CodeGenFunction::AutoVarEmission 816CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) { 817 QualType Ty = D.getType(); 818 819 AutoVarEmission emission(D); 820 821 bool isByRef = D.hasAttr<BlocksAttr>(); 822 emission.IsByRef = isByRef; 823 824 CharUnits alignment = getContext().getDeclAlign(&D); 825 emission.Alignment = alignment; 826 827 // If the type is variably-modified, emit all the VLA sizes for it. 828 if (Ty->isVariablyModifiedType()) 829 EmitVariablyModifiedType(Ty); 830 831 llvm::Value *DeclPtr; 832 if (Ty->isConstantSizeType()) { 833 bool NRVO = getLangOpts().ElideConstructors && 834 D.isNRVOVariable(); 835 836 // If this value is a POD array or struct with a statically 837 // determinable constant initializer, there are optimizations we can do. 838 // 839 // TODO: We should constant-evaluate the initializer of any variable, 840 // as long as it is initialized by a constant expression. Currently, 841 // isConstantInitializer produces wrong answers for structs with 842 // reference or bitfield members, and a few other cases, and checking 843 // for POD-ness protects us from some of these. 844 if (D.getInit() && 845 (Ty->isArrayType() || Ty->isRecordType()) && 846 (Ty.isPODType(getContext()) || 847 getContext().getBaseElementType(Ty)->isObjCObjectPointerType()) && 848 D.getInit()->isConstantInitializer(getContext(), false)) { 849 850 // If the variable's a const type, and it's neither an NRVO 851 // candidate nor a __block variable and has no mutable members, 852 // emit it as a global instead. 853 if (CGM.getCodeGenOpts().MergeAllConstants && !NRVO && !isByRef && 854 CGM.isTypeConstant(Ty, true)) { 855 EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage); 856 857 emission.Address = 0; // signal this condition to later callbacks 858 assert(emission.wasEmittedAsGlobal()); 859 return emission; 860 } 861 862 // Otherwise, tell the initialization code that we're in this case. 863 emission.IsConstantAggregate = true; 864 } 865 866 // A normal fixed sized variable becomes an alloca in the entry block, 867 // unless it's an NRVO variable. 868 llvm::Type *LTy = ConvertTypeForMem(Ty); 869 870 if (NRVO) { 871 // The named return value optimization: allocate this variable in the 872 // return slot, so that we can elide the copy when returning this 873 // variable (C++0x [class.copy]p34). 874 DeclPtr = ReturnValue; 875 876 if (const RecordType *RecordTy = Ty->getAs<RecordType>()) { 877 if (!cast<CXXRecordDecl>(RecordTy->getDecl())->hasTrivialDestructor()) { 878 // Create a flag that is used to indicate when the NRVO was applied 879 // to this variable. Set it to zero to indicate that NRVO was not 880 // applied. 881 llvm::Value *Zero = Builder.getFalse(); 882 llvm::Value *NRVOFlag = CreateTempAlloca(Zero->getType(), "nrvo"); 883 EnsureInsertPoint(); 884 Builder.CreateStore(Zero, NRVOFlag); 885 886 // Record the NRVO flag for this variable. 887 NRVOFlags[&D] = NRVOFlag; 888 emission.NRVOFlag = NRVOFlag; 889 } 890 } 891 } else { 892 if (isByRef) 893 LTy = BuildByRefType(&D); 894 895 llvm::AllocaInst *Alloc = CreateTempAlloca(LTy); 896 Alloc->setName(D.getName()); 897 898 CharUnits allocaAlignment = alignment; 899 if (isByRef) 900 allocaAlignment = std::max(allocaAlignment, 901 getContext().toCharUnitsFromBits(Target.getPointerAlign(0))); 902 Alloc->setAlignment(allocaAlignment.getQuantity()); 903 DeclPtr = Alloc; 904 905 // Emit a lifetime intrinsic if meaningful. There's no point 906 // in doing this if we don't have a valid insertion point (?). 907 uint64_t size = CGM.getDataLayout().getTypeAllocSize(LTy); 908 if (HaveInsertPoint() && shouldUseLifetimeMarkers(*this, D, size)) { 909 llvm::Value *sizeV = llvm::ConstantInt::get(Int64Ty, size); 910 911 emission.SizeForLifetimeMarkers = sizeV; 912 llvm::Value *castAddr = Builder.CreateBitCast(Alloc, Int8PtrTy); 913 Builder.CreateCall2(CGM.getLLVMLifetimeStartFn(), sizeV, castAddr) 914 ->setDoesNotThrow(); 915 } else { 916 assert(!emission.useLifetimeMarkers()); 917 } 918 } 919 } else { 920 EnsureInsertPoint(); 921 922 if (!DidCallStackSave) { 923 // Save the stack. 924 llvm::Value *Stack = CreateTempAlloca(Int8PtrTy, "saved_stack"); 925 926 llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave); 927 llvm::Value *V = Builder.CreateCall(F); 928 929 Builder.CreateStore(V, Stack); 930 931 DidCallStackSave = true; 932 933 // Push a cleanup block and restore the stack there. 934 // FIXME: in general circumstances, this should be an EH cleanup. 935 EHStack.pushCleanup<CallStackRestore>(NormalCleanup, Stack); 936 } 937 938 llvm::Value *elementCount; 939 QualType elementType; 940 llvm::tie(elementCount, elementType) = getVLASize(Ty); 941 942 llvm::Type *llvmTy = ConvertTypeForMem(elementType); 943 944 // Allocate memory for the array. 945 llvm::AllocaInst *vla = Builder.CreateAlloca(llvmTy, elementCount, "vla"); 946 vla->setAlignment(alignment.getQuantity()); 947 948 DeclPtr = vla; 949 } 950 951 llvm::Value *&DMEntry = LocalDeclMap[&D]; 952 assert(DMEntry == 0 && "Decl already exists in localdeclmap!"); 953 DMEntry = DeclPtr; 954 emission.Address = DeclPtr; 955 956 // Emit debug info for local var declaration. 957 if (HaveInsertPoint()) 958 if (CGDebugInfo *DI = getDebugInfo()) { 959 if (CGM.getCodeGenOpts().getDebugInfo() 960 >= CodeGenOptions::LimitedDebugInfo) { 961 DI->setLocation(D.getLocation()); 962 DI->EmitDeclareOfAutoVariable(&D, DeclPtr, Builder); 963 } 964 } 965 966 if (D.hasAttr<AnnotateAttr>()) 967 EmitVarAnnotations(&D, emission.Address); 968 969 return emission; 970} 971 972/// Determines whether the given __block variable is potentially 973/// captured by the given expression. 974static bool isCapturedBy(const VarDecl &var, const Expr *e) { 975 // Skip the most common kinds of expressions that make 976 // hierarchy-walking expensive. 977 e = e->IgnoreParenCasts(); 978 979 if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) { 980 const BlockDecl *block = be->getBlockDecl(); 981 for (BlockDecl::capture_const_iterator i = block->capture_begin(), 982 e = block->capture_end(); i != e; ++i) { 983 if (i->getVariable() == &var) 984 return true; 985 } 986 987 // No need to walk into the subexpressions. 988 return false; 989 } 990 991 if (const StmtExpr *SE = dyn_cast<StmtExpr>(e)) { 992 const CompoundStmt *CS = SE->getSubStmt(); 993 for (CompoundStmt::const_body_iterator BI = CS->body_begin(), 994 BE = CS->body_end(); BI != BE; ++BI) 995 if (Expr *E = dyn_cast<Expr>((*BI))) { 996 if (isCapturedBy(var, E)) 997 return true; 998 } 999 else if (DeclStmt *DS = dyn_cast<DeclStmt>((*BI))) { 1000 // special case declarations 1001 for (DeclStmt::decl_iterator I = DS->decl_begin(), E = DS->decl_end(); 1002 I != E; ++I) { 1003 if (VarDecl *VD = dyn_cast<VarDecl>((*I))) { 1004 Expr *Init = VD->getInit(); 1005 if (Init && isCapturedBy(var, Init)) 1006 return true; 1007 } 1008 } 1009 } 1010 else 1011 // FIXME. Make safe assumption assuming arbitrary statements cause capturing. 1012 // Later, provide code to poke into statements for capture analysis. 1013 return true; 1014 return false; 1015 } 1016 1017 for (Stmt::const_child_range children = e->children(); children; ++children) 1018 if (isCapturedBy(var, cast<Expr>(*children))) 1019 return true; 1020 1021 return false; 1022} 1023 1024/// \brief Determine whether the given initializer is trivial in the sense 1025/// that it requires no code to be generated. 1026static bool isTrivialInitializer(const Expr *Init) { 1027 if (!Init) 1028 return true; 1029 1030 if (const CXXConstructExpr *Construct = dyn_cast<CXXConstructExpr>(Init)) 1031 if (CXXConstructorDecl *Constructor = Construct->getConstructor()) 1032 if (Constructor->isTrivial() && 1033 Constructor->isDefaultConstructor() && 1034 !Construct->requiresZeroInitialization()) 1035 return true; 1036 1037 return false; 1038} 1039void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) { 1040 assert(emission.Variable && "emission was not valid!"); 1041 1042 // If this was emitted as a global constant, we're done. 1043 if (emission.wasEmittedAsGlobal()) return; 1044 1045 const VarDecl &D = *emission.Variable; 1046 QualType type = D.getType(); 1047 1048 // If this local has an initializer, emit it now. 1049 const Expr *Init = D.getInit(); 1050 1051 // If we are at an unreachable point, we don't need to emit the initializer 1052 // unless it contains a label. 1053 if (!HaveInsertPoint()) { 1054 if (!Init || !ContainsLabel(Init)) return; 1055 EnsureInsertPoint(); 1056 } 1057 1058 // Initialize the structure of a __block variable. 1059 if (emission.IsByRef) 1060 emitByrefStructureInit(emission); 1061 1062 if (isTrivialInitializer(Init)) 1063 return; 1064 1065 CharUnits alignment = emission.Alignment; 1066 1067 // Check whether this is a byref variable that's potentially 1068 // captured and moved by its own initializer. If so, we'll need to 1069 // emit the initializer first, then copy into the variable. 1070 bool capturedByInit = emission.IsByRef && isCapturedBy(D, Init); 1071 1072 llvm::Value *Loc = 1073 capturedByInit ? emission.Address : emission.getObjectAddress(*this); 1074 1075 llvm::Constant *constant = 0; 1076 if (emission.IsConstantAggregate) { 1077 assert(!capturedByInit && "constant init contains a capturing block?"); 1078 constant = CGM.EmitConstantInit(D, this); 1079 } 1080 1081 if (!constant) { 1082 LValue lv = MakeAddrLValue(Loc, type, alignment); 1083 lv.setNonGC(true); 1084 return EmitExprAsInit(Init, &D, lv, capturedByInit); 1085 } 1086 1087 // If this is a simple aggregate initialization, we can optimize it 1088 // in various ways. 1089 bool isVolatile = type.isVolatileQualified(); 1090 1091 llvm::Value *SizeVal = 1092 llvm::ConstantInt::get(IntPtrTy, 1093 getContext().getTypeSizeInChars(type).getQuantity()); 1094 1095 llvm::Type *BP = Int8PtrTy; 1096 if (Loc->getType() != BP) 1097 Loc = Builder.CreateBitCast(Loc, BP); 1098 1099 // If the initializer is all or mostly zeros, codegen with memset then do 1100 // a few stores afterward. 1101 if (shouldUseMemSetPlusStoresToInitialize(constant, 1102 CGM.getDataLayout().getTypeAllocSize(constant->getType()))) { 1103 Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, 0), SizeVal, 1104 alignment.getQuantity(), isVolatile); 1105 // Zero and undef don't require a stores. 1106 if (!constant->isNullValue() && !isa<llvm::UndefValue>(constant)) { 1107 Loc = Builder.CreateBitCast(Loc, constant->getType()->getPointerTo()); 1108 emitStoresForInitAfterMemset(constant, Loc, isVolatile, Builder); 1109 } 1110 } else { 1111 // Otherwise, create a temporary global with the initializer then 1112 // memcpy from the global to the alloca. 1113 std::string Name = GetStaticDeclName(*this, D, "."); 1114 llvm::GlobalVariable *GV = 1115 new llvm::GlobalVariable(CGM.getModule(), constant->getType(), true, 1116 llvm::GlobalValue::PrivateLinkage, 1117 constant, Name); 1118 GV->setAlignment(alignment.getQuantity()); 1119 GV->setUnnamedAddr(true); 1120 1121 llvm::Value *SrcPtr = GV; 1122 if (SrcPtr->getType() != BP) 1123 SrcPtr = Builder.CreateBitCast(SrcPtr, BP); 1124 1125 Builder.CreateMemCpy(Loc, SrcPtr, SizeVal, alignment.getQuantity(), 1126 isVolatile); 1127 } 1128} 1129 1130/// Emit an expression as an initializer for a variable at the given 1131/// location. The expression is not necessarily the normal 1132/// initializer for the variable, and the address is not necessarily 1133/// its normal location. 1134/// 1135/// \param init the initializing expression 1136/// \param var the variable to act as if we're initializing 1137/// \param loc the address to initialize; its type is a pointer 1138/// to the LLVM mapping of the variable's type 1139/// \param alignment the alignment of the address 1140/// \param capturedByInit true if the variable is a __block variable 1141/// whose address is potentially changed by the initializer 1142void CodeGenFunction::EmitExprAsInit(const Expr *init, 1143 const ValueDecl *D, 1144 LValue lvalue, 1145 bool capturedByInit) { 1146 QualType type = D->getType(); 1147 1148 if (type->isReferenceType()) { 1149 RValue rvalue = EmitReferenceBindingToExpr(init, D); 1150 if (capturedByInit) 1151 drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 1152 EmitStoreThroughLValue(rvalue, lvalue, true); 1153 return; 1154 } 1155 switch (getEvaluationKind(type)) { 1156 case TEK_Scalar: 1157 EmitScalarInit(init, D, lvalue, capturedByInit); 1158 return; 1159 case TEK_Complex: { 1160 ComplexPairTy complex = EmitComplexExpr(init); 1161 if (capturedByInit) 1162 drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D)); 1163 EmitStoreOfComplex(complex, lvalue, /*init*/ true); 1164 return; 1165 } 1166 case TEK_Aggregate: 1167 if (type->isAtomicType()) { 1168 EmitAtomicInit(const_cast<Expr*>(init), lvalue); 1169 } else { 1170 // TODO: how can we delay here if D is captured by its initializer? 1171 EmitAggExpr(init, AggValueSlot::forLValue(lvalue, 1172 AggValueSlot::IsDestructed, 1173 AggValueSlot::DoesNotNeedGCBarriers, 1174 AggValueSlot::IsNotAliased)); 1175 } 1176 MaybeEmitStdInitializerListCleanup(lvalue.getAddress(), init); 1177 return; 1178 } 1179 llvm_unreachable("bad evaluation kind"); 1180} 1181 1182/// Enter a destroy cleanup for the given local variable. 1183void CodeGenFunction::emitAutoVarTypeCleanup( 1184 const CodeGenFunction::AutoVarEmission &emission, 1185 QualType::DestructionKind dtorKind) { 1186 assert(dtorKind != QualType::DK_none); 1187 1188 // Note that for __block variables, we want to destroy the 1189 // original stack object, not the possibly forwarded object. 1190 llvm::Value *addr = emission.getObjectAddress(*this); 1191 1192 const VarDecl *var = emission.Variable; 1193 QualType type = var->getType(); 1194 1195 CleanupKind cleanupKind = NormalAndEHCleanup; 1196 CodeGenFunction::Destroyer *destroyer = 0; 1197 1198 switch (dtorKind) { 1199 case QualType::DK_none: 1200 llvm_unreachable("no cleanup for trivially-destructible variable"); 1201 1202 case QualType::DK_cxx_destructor: 1203 // If there's an NRVO flag on the emission, we need a different 1204 // cleanup. 1205 if (emission.NRVOFlag) { 1206 assert(!type->isArrayType()); 1207 CXXDestructorDecl *dtor = type->getAsCXXRecordDecl()->getDestructor(); 1208 EHStack.pushCleanup<DestroyNRVOVariable>(cleanupKind, addr, dtor, 1209 emission.NRVOFlag); 1210 return; 1211 } 1212 break; 1213 1214 case QualType::DK_objc_strong_lifetime: 1215 // Suppress cleanups for pseudo-strong variables. 1216 if (var->isARCPseudoStrong()) return; 1217 1218 // Otherwise, consider whether to use an EH cleanup or not. 1219 cleanupKind = getARCCleanupKind(); 1220 1221 // Use the imprecise destroyer by default. 1222 if (!var->hasAttr<ObjCPreciseLifetimeAttr>()) 1223 destroyer = CodeGenFunction::destroyARCStrongImprecise; 1224 break; 1225 1226 case QualType::DK_objc_weak_lifetime: 1227 break; 1228 } 1229 1230 // If we haven't chosen a more specific destroyer, use the default. 1231 if (!destroyer) destroyer = getDestroyer(dtorKind); 1232 1233 // Use an EH cleanup in array destructors iff the destructor itself 1234 // is being pushed as an EH cleanup. 1235 bool useEHCleanup = (cleanupKind & EHCleanup); 1236 EHStack.pushCleanup<DestroyObject>(cleanupKind, addr, type, destroyer, 1237 useEHCleanup); 1238} 1239 1240void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) { 1241 assert(emission.Variable && "emission was not valid!"); 1242 1243 // If this was emitted as a global constant, we're done. 1244 if (emission.wasEmittedAsGlobal()) return; 1245 1246 // If we don't have an insertion point, we're done. Sema prevents 1247 // us from jumping into any of these scopes anyway. 1248 if (!HaveInsertPoint()) return; 1249 1250 const VarDecl &D = *emission.Variable; 1251 1252 // Make sure we call @llvm.lifetime.end. This needs to happen 1253 // *last*, so the cleanup needs to be pushed *first*. 1254 if (emission.useLifetimeMarkers()) { 1255 EHStack.pushCleanup<CallLifetimeEnd>(NormalCleanup, 1256 emission.getAllocatedAddress(), 1257 emission.getSizeForLifetimeMarkers()); 1258 } 1259 1260 // Check the type for a cleanup. 1261 if (QualType::DestructionKind dtorKind = D.getType().isDestructedType()) 1262 emitAutoVarTypeCleanup(emission, dtorKind); 1263 1264 // In GC mode, honor objc_precise_lifetime. 1265 if (getLangOpts().getGC() != LangOptions::NonGC && 1266 D.hasAttr<ObjCPreciseLifetimeAttr>()) { 1267 EHStack.pushCleanup<ExtendGCLifetime>(NormalCleanup, &D); 1268 } 1269 1270 // Handle the cleanup attribute. 1271 if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) { 1272 const FunctionDecl *FD = CA->getFunctionDecl(); 1273 1274 llvm::Constant *F = CGM.GetAddrOfFunction(FD); 1275 assert(F && "Could not find function!"); 1276 1277 const CGFunctionInfo &Info = CGM.getTypes().arrangeFunctionDeclaration(FD); 1278 EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup, F, &Info, &D); 1279 } 1280 1281 // If this is a block variable, call _Block_object_destroy 1282 // (on the unforwarded address). 1283 if (emission.IsByRef) 1284 enterByrefCleanup(emission); 1285} 1286 1287CodeGenFunction::Destroyer * 1288CodeGenFunction::getDestroyer(QualType::DestructionKind kind) { 1289 switch (kind) { 1290 case QualType::DK_none: llvm_unreachable("no destroyer for trivial dtor"); 1291 case QualType::DK_cxx_destructor: 1292 return destroyCXXObject; 1293 case QualType::DK_objc_strong_lifetime: 1294 return destroyARCStrongPrecise; 1295 case QualType::DK_objc_weak_lifetime: 1296 return destroyARCWeak; 1297 } 1298 llvm_unreachable("Unknown DestructionKind"); 1299} 1300 1301/// pushEHDestroy - Push the standard destructor for the given type as 1302/// an EH-only cleanup. 1303void CodeGenFunction::pushEHDestroy(QualType::DestructionKind dtorKind, 1304 llvm::Value *addr, QualType type) { 1305 assert(dtorKind && "cannot push destructor for trivial type"); 1306 assert(needsEHCleanup(dtorKind)); 1307 1308 pushDestroy(EHCleanup, addr, type, getDestroyer(dtorKind), true); 1309} 1310 1311/// pushDestroy - Push the standard destructor for the given type as 1312/// at least a normal cleanup. 1313void CodeGenFunction::pushDestroy(QualType::DestructionKind dtorKind, 1314 llvm::Value *addr, QualType type) { 1315 assert(dtorKind && "cannot push destructor for trivial type"); 1316 1317 CleanupKind cleanupKind = getCleanupKind(dtorKind); 1318 pushDestroy(cleanupKind, addr, type, getDestroyer(dtorKind), 1319 cleanupKind & EHCleanup); 1320} 1321 1322void CodeGenFunction::pushDestroy(CleanupKind cleanupKind, llvm::Value *addr, 1323 QualType type, Destroyer *destroyer, 1324 bool useEHCleanupForArray) { 1325 pushFullExprCleanup<DestroyObject>(cleanupKind, addr, type, 1326 destroyer, useEHCleanupForArray); 1327} 1328 1329/// emitDestroy - Immediately perform the destruction of the given 1330/// object. 1331/// 1332/// \param addr - the address of the object; a type* 1333/// \param type - the type of the object; if an array type, all 1334/// objects are destroyed in reverse order 1335/// \param destroyer - the function to call to destroy individual 1336/// elements 1337/// \param useEHCleanupForArray - whether an EH cleanup should be 1338/// used when destroying array elements, in case one of the 1339/// destructions throws an exception 1340void CodeGenFunction::emitDestroy(llvm::Value *addr, QualType type, 1341 Destroyer *destroyer, 1342 bool useEHCleanupForArray) { 1343 const ArrayType *arrayType = getContext().getAsArrayType(type); 1344 if (!arrayType) 1345 return destroyer(*this, addr, type); 1346 1347 llvm::Value *begin = addr; 1348 llvm::Value *length = emitArrayLength(arrayType, type, begin); 1349 1350 // Normally we have to check whether the array is zero-length. 1351 bool checkZeroLength = true; 1352 1353 // But if the array length is constant, we can suppress that. 1354 if (llvm::ConstantInt *constLength = dyn_cast<llvm::ConstantInt>(length)) { 1355 // ...and if it's constant zero, we can just skip the entire thing. 1356 if (constLength->isZero()) return; 1357 checkZeroLength = false; 1358 } 1359 1360 llvm::Value *end = Builder.CreateInBoundsGEP(begin, length); 1361 emitArrayDestroy(begin, end, type, destroyer, 1362 checkZeroLength, useEHCleanupForArray); 1363} 1364 1365/// emitArrayDestroy - Destroys all the elements of the given array, 1366/// beginning from last to first. The array cannot be zero-length. 1367/// 1368/// \param begin - a type* denoting the first element of the array 1369/// \param end - a type* denoting one past the end of the array 1370/// \param type - the element type of the array 1371/// \param destroyer - the function to call to destroy elements 1372/// \param useEHCleanup - whether to push an EH cleanup to destroy 1373/// the remaining elements in case the destruction of a single 1374/// element throws 1375void CodeGenFunction::emitArrayDestroy(llvm::Value *begin, 1376 llvm::Value *end, 1377 QualType type, 1378 Destroyer *destroyer, 1379 bool checkZeroLength, 1380 bool useEHCleanup) { 1381 assert(!type->isArrayType()); 1382 1383 // The basic structure here is a do-while loop, because we don't 1384 // need to check for the zero-element case. 1385 llvm::BasicBlock *bodyBB = createBasicBlock("arraydestroy.body"); 1386 llvm::BasicBlock *doneBB = createBasicBlock("arraydestroy.done"); 1387 1388 if (checkZeroLength) { 1389 llvm::Value *isEmpty = Builder.CreateICmpEQ(begin, end, 1390 "arraydestroy.isempty"); 1391 Builder.CreateCondBr(isEmpty, doneBB, bodyBB); 1392 } 1393 1394 // Enter the loop body, making that address the current address. 1395 llvm::BasicBlock *entryBB = Builder.GetInsertBlock(); 1396 EmitBlock(bodyBB); 1397 llvm::PHINode *elementPast = 1398 Builder.CreatePHI(begin->getType(), 2, "arraydestroy.elementPast"); 1399 elementPast->addIncoming(end, entryBB); 1400 1401 // Shift the address back by one element. 1402 llvm::Value *negativeOne = llvm::ConstantInt::get(SizeTy, -1, true); 1403 llvm::Value *element = Builder.CreateInBoundsGEP(elementPast, negativeOne, 1404 "arraydestroy.element"); 1405 1406 if (useEHCleanup) 1407 pushRegularPartialArrayCleanup(begin, element, type, destroyer); 1408 1409 // Perform the actual destruction there. 1410 destroyer(*this, element, type); 1411 1412 if (useEHCleanup) 1413 PopCleanupBlock(); 1414 1415 // Check whether we've reached the end. 1416 llvm::Value *done = Builder.CreateICmpEQ(element, begin, "arraydestroy.done"); 1417 Builder.CreateCondBr(done, doneBB, bodyBB); 1418 elementPast->addIncoming(element, Builder.GetInsertBlock()); 1419 1420 // Done. 1421 EmitBlock(doneBB); 1422} 1423 1424/// Perform partial array destruction as if in an EH cleanup. Unlike 1425/// emitArrayDestroy, the element type here may still be an array type. 1426static void emitPartialArrayDestroy(CodeGenFunction &CGF, 1427 llvm::Value *begin, llvm::Value *end, 1428 QualType type, 1429 CodeGenFunction::Destroyer *destroyer) { 1430 // If the element type is itself an array, drill down. 1431 unsigned arrayDepth = 0; 1432 while (const ArrayType *arrayType = CGF.getContext().getAsArrayType(type)) { 1433 // VLAs don't require a GEP index to walk into. 1434 if (!isa<VariableArrayType>(arrayType)) 1435 arrayDepth++; 1436 type = arrayType->getElementType(); 1437 } 1438 1439 if (arrayDepth) { 1440 llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, arrayDepth+1); 1441 1442 SmallVector<llvm::Value*,4> gepIndices(arrayDepth, zero); 1443 begin = CGF.Builder.CreateInBoundsGEP(begin, gepIndices, "pad.arraybegin"); 1444 end = CGF.Builder.CreateInBoundsGEP(end, gepIndices, "pad.arrayend"); 1445 } 1446 1447 // Destroy the array. We don't ever need an EH cleanup because we 1448 // assume that we're in an EH cleanup ourselves, so a throwing 1449 // destructor causes an immediate terminate. 1450 CGF.emitArrayDestroy(begin, end, type, destroyer, 1451 /*checkZeroLength*/ true, /*useEHCleanup*/ false); 1452} 1453 1454namespace { 1455 /// RegularPartialArrayDestroy - a cleanup which performs a partial 1456 /// array destroy where the end pointer is regularly determined and 1457 /// does not need to be loaded from a local. 1458 class RegularPartialArrayDestroy : public EHScopeStack::Cleanup { 1459 llvm::Value *ArrayBegin; 1460 llvm::Value *ArrayEnd; 1461 QualType ElementType; 1462 CodeGenFunction::Destroyer *Destroyer; 1463 public: 1464 RegularPartialArrayDestroy(llvm::Value *arrayBegin, llvm::Value *arrayEnd, 1465 QualType elementType, 1466 CodeGenFunction::Destroyer *destroyer) 1467 : ArrayBegin(arrayBegin), ArrayEnd(arrayEnd), 1468 ElementType(elementType), Destroyer(destroyer) {} 1469 1470 void Emit(CodeGenFunction &CGF, Flags flags) { 1471 emitPartialArrayDestroy(CGF, ArrayBegin, ArrayEnd, 1472 ElementType, Destroyer); 1473 } 1474 }; 1475 1476 /// IrregularPartialArrayDestroy - a cleanup which performs a 1477 /// partial array destroy where the end pointer is irregularly 1478 /// determined and must be loaded from a local. 1479 class IrregularPartialArrayDestroy : public EHScopeStack::Cleanup { 1480 llvm::Value *ArrayBegin; 1481 llvm::Value *ArrayEndPointer; 1482 QualType ElementType; 1483 CodeGenFunction::Destroyer *Destroyer; 1484 public: 1485 IrregularPartialArrayDestroy(llvm::Value *arrayBegin, 1486 llvm::Value *arrayEndPointer, 1487 QualType elementType, 1488 CodeGenFunction::Destroyer *destroyer) 1489 : ArrayBegin(arrayBegin), ArrayEndPointer(arrayEndPointer), 1490 ElementType(elementType), Destroyer(destroyer) {} 1491 1492 void Emit(CodeGenFunction &CGF, Flags flags) { 1493 llvm::Value *arrayEnd = CGF.Builder.CreateLoad(ArrayEndPointer); 1494 emitPartialArrayDestroy(CGF, ArrayBegin, arrayEnd, 1495 ElementType, Destroyer); 1496 } 1497 }; 1498} 1499 1500/// pushIrregularPartialArrayCleanup - Push an EH cleanup to destroy 1501/// already-constructed elements of the given array. The cleanup 1502/// may be popped with DeactivateCleanupBlock or PopCleanupBlock. 1503/// 1504/// \param elementType - the immediate element type of the array; 1505/// possibly still an array type 1506void CodeGenFunction::pushIrregularPartialArrayCleanup(llvm::Value *arrayBegin, 1507 llvm::Value *arrayEndPointer, 1508 QualType elementType, 1509 Destroyer *destroyer) { 1510 pushFullExprCleanup<IrregularPartialArrayDestroy>(EHCleanup, 1511 arrayBegin, arrayEndPointer, 1512 elementType, destroyer); 1513} 1514 1515/// pushRegularPartialArrayCleanup - Push an EH cleanup to destroy 1516/// already-constructed elements of the given array. The cleanup 1517/// may be popped with DeactivateCleanupBlock or PopCleanupBlock. 1518/// 1519/// \param elementType - the immediate element type of the array; 1520/// possibly still an array type 1521void CodeGenFunction::pushRegularPartialArrayCleanup(llvm::Value *arrayBegin, 1522 llvm::Value *arrayEnd, 1523 QualType elementType, 1524 Destroyer *destroyer) { 1525 pushFullExprCleanup<RegularPartialArrayDestroy>(EHCleanup, 1526 arrayBegin, arrayEnd, 1527 elementType, destroyer); 1528} 1529 1530/// Lazily declare the @llvm.lifetime.start intrinsic. 1531llvm::Constant *CodeGenModule::getLLVMLifetimeStartFn() { 1532 if (LifetimeStartFn) return LifetimeStartFn; 1533 LifetimeStartFn = llvm::Intrinsic::getDeclaration(&getModule(), 1534 llvm::Intrinsic::lifetime_start); 1535 return LifetimeStartFn; 1536} 1537 1538/// Lazily declare the @llvm.lifetime.end intrinsic. 1539llvm::Constant *CodeGenModule::getLLVMLifetimeEndFn() { 1540 if (LifetimeEndFn) return LifetimeEndFn; 1541 LifetimeEndFn = llvm::Intrinsic::getDeclaration(&getModule(), 1542 llvm::Intrinsic::lifetime_end); 1543 return LifetimeEndFn; 1544} 1545 1546namespace { 1547 /// A cleanup to perform a release of an object at the end of a 1548 /// function. This is used to balance out the incoming +1 of a 1549 /// ns_consumed argument when we can't reasonably do that just by 1550 /// not doing the initial retain for a __block argument. 1551 struct ConsumeARCParameter : EHScopeStack::Cleanup { 1552 ConsumeARCParameter(llvm::Value *param, 1553 ARCPreciseLifetime_t precise) 1554 : Param(param), Precise(precise) {} 1555 1556 llvm::Value *Param; 1557 ARCPreciseLifetime_t Precise; 1558 1559 void Emit(CodeGenFunction &CGF, Flags flags) { 1560 CGF.EmitARCRelease(Param, Precise); 1561 } 1562 }; 1563} 1564 1565/// Emit an alloca (or GlobalValue depending on target) 1566/// for the specified parameter and set up LocalDeclMap. 1567void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg, 1568 unsigned ArgNo) { 1569 // FIXME: Why isn't ImplicitParamDecl a ParmVarDecl? 1570 assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) && 1571 "Invalid argument to EmitParmDecl"); 1572 1573 Arg->setName(D.getName()); 1574 1575 QualType Ty = D.getType(); 1576 1577 // Use better IR generation for certain implicit parameters. 1578 if (isa<ImplicitParamDecl>(D)) { 1579 // The only implicit argument a block has is its literal. 1580 if (BlockInfo) { 1581 LocalDeclMap[&D] = Arg; 1582 llvm::Value *LocalAddr = 0; 1583 if (CGM.getCodeGenOpts().OptimizationLevel == 0) { 1584 // Allocate a stack slot to let the debug info survive the RA. 1585 llvm::AllocaInst *Alloc = CreateTempAlloca(ConvertTypeForMem(Ty), 1586 D.getName() + ".addr"); 1587 Alloc->setAlignment(getContext().getDeclAlign(&D).getQuantity()); 1588 LValue lv = MakeAddrLValue(Alloc, Ty, getContext().getDeclAlign(&D)); 1589 EmitStoreOfScalar(Arg, lv, /* isInitialization */ true); 1590 LocalAddr = Builder.CreateLoad(Alloc); 1591 } 1592 1593 if (CGDebugInfo *DI = getDebugInfo()) { 1594 if (CGM.getCodeGenOpts().getDebugInfo() 1595 >= CodeGenOptions::LimitedDebugInfo) { 1596 DI->setLocation(D.getLocation()); 1597 DI->EmitDeclareOfBlockLiteralArgVariable(*BlockInfo, Arg, LocalAddr, Builder); 1598 } 1599 } 1600 1601 return; 1602 } 1603 } 1604 1605 llvm::Value *DeclPtr; 1606 // If this is an aggregate or variable sized value, reuse the input pointer. 1607 if (!Ty->isConstantSizeType() || 1608 !CodeGenFunction::hasScalarEvaluationKind(Ty)) { 1609 DeclPtr = Arg; 1610 } else { 1611 // Otherwise, create a temporary to hold the value. 1612 llvm::AllocaInst *Alloc = CreateTempAlloca(ConvertTypeForMem(Ty), 1613 D.getName() + ".addr"); 1614 CharUnits Align = getContext().getDeclAlign(&D); 1615 Alloc->setAlignment(Align.getQuantity()); 1616 DeclPtr = Alloc; 1617 1618 bool doStore = true; 1619 1620 Qualifiers qs = Ty.getQualifiers(); 1621 LValue lv = MakeAddrLValue(DeclPtr, Ty, Align); 1622 if (Qualifiers::ObjCLifetime lt = qs.getObjCLifetime()) { 1623 // We honor __attribute__((ns_consumed)) for types with lifetime. 1624 // For __strong, it's handled by just skipping the initial retain; 1625 // otherwise we have to balance out the initial +1 with an extra 1626 // cleanup to do the release at the end of the function. 1627 bool isConsumed = D.hasAttr<NSConsumedAttr>(); 1628 1629 // 'self' is always formally __strong, but if this is not an 1630 // init method then we don't want to retain it. 1631 if (D.isARCPseudoStrong()) { 1632 const ObjCMethodDecl *method = cast<ObjCMethodDecl>(CurCodeDecl); 1633 assert(&D == method->getSelfDecl()); 1634 assert(lt == Qualifiers::OCL_Strong); 1635 assert(qs.hasConst()); 1636 assert(method->getMethodFamily() != OMF_init); 1637 (void) method; 1638 lt = Qualifiers::OCL_ExplicitNone; 1639 } 1640 1641 if (lt == Qualifiers::OCL_Strong) { 1642 if (!isConsumed) { 1643 if (CGM.getCodeGenOpts().OptimizationLevel == 0) { 1644 // use objc_storeStrong(&dest, value) for retaining the 1645 // object. But first, store a null into 'dest' because 1646 // objc_storeStrong attempts to release its old value. 1647 llvm::Value * Null = CGM.EmitNullConstant(D.getType()); 1648 EmitStoreOfScalar(Null, lv, /* isInitialization */ true); 1649 EmitARCStoreStrongCall(lv.getAddress(), Arg, true); 1650 doStore = false; 1651 } 1652 else 1653 // Don't use objc_retainBlock for block pointers, because we 1654 // don't want to Block_copy something just because we got it 1655 // as a parameter. 1656 Arg = EmitARCRetainNonBlock(Arg); 1657 } 1658 } else { 1659 // Push the cleanup for a consumed parameter. 1660 if (isConsumed) { 1661 ARCPreciseLifetime_t precise = (D.hasAttr<ObjCPreciseLifetimeAttr>() 1662 ? ARCPreciseLifetime : ARCImpreciseLifetime); 1663 EHStack.pushCleanup<ConsumeARCParameter>(getARCCleanupKind(), Arg, 1664 precise); 1665 } 1666 1667 if (lt == Qualifiers::OCL_Weak) { 1668 EmitARCInitWeak(DeclPtr, Arg); 1669 doStore = false; // The weak init is a store, no need to do two. 1670 } 1671 } 1672 1673 // Enter the cleanup scope. 1674 EmitAutoVarWithLifetime(*this, D, DeclPtr, lt); 1675 } 1676 1677 // Store the initial value into the alloca. 1678 if (doStore) 1679 EmitStoreOfScalar(Arg, lv, /* isInitialization */ true); 1680 } 1681 1682 llvm::Value *&DMEntry = LocalDeclMap[&D]; 1683 assert(DMEntry == 0 && "Decl already exists in localdeclmap!"); 1684 DMEntry = DeclPtr; 1685 1686 // Emit debug info for param declaration. 1687 if (CGDebugInfo *DI = getDebugInfo()) { 1688 if (CGM.getCodeGenOpts().getDebugInfo() 1689 >= CodeGenOptions::LimitedDebugInfo) { 1690 DI->EmitDeclareOfArgVariable(&D, DeclPtr, ArgNo, Builder); 1691 } 1692 } 1693 1694 if (D.hasAttr<AnnotateAttr>()) 1695 EmitVarAnnotations(&D, DeclPtr); 1696} 1697