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/CodeGen/CGFunctionInfo.h"
25#include "clang/Frontend/CodeGenOptions.h"
26#include "llvm/IR/DataLayout.h"
27#include "llvm/IR/GlobalVariable.h"
28#include "llvm/IR/Intrinsics.h"
29#include "llvm/IR/Type.h"
30using namespace clang;
31using namespace CodeGen;
32
33
34void CodeGenFunction::EmitDecl(const Decl &D) {
35  switch (D.getKind()) {
36  case Decl::TranslationUnit:
37  case Decl::Namespace:
38  case Decl::UnresolvedUsingTypename:
39  case Decl::ClassTemplateSpecialization:
40  case Decl::ClassTemplatePartialSpecialization:
41  case Decl::VarTemplateSpecialization:
42  case Decl::VarTemplatePartialSpecialization:
43  case Decl::TemplateTypeParm:
44  case Decl::UnresolvedUsingValue:
45  case Decl::NonTypeTemplateParm:
46  case Decl::CXXMethod:
47  case Decl::CXXConstructor:
48  case Decl::CXXDestructor:
49  case Decl::CXXConversion:
50  case Decl::Field:
51  case Decl::MSProperty:
52  case Decl::IndirectField:
53  case Decl::ObjCIvar:
54  case Decl::ObjCAtDefsField:
55  case Decl::ParmVar:
56  case Decl::ImplicitParam:
57  case Decl::ClassTemplate:
58  case Decl::VarTemplate:
59  case Decl::FunctionTemplate:
60  case Decl::TypeAliasTemplate:
61  case Decl::TemplateTemplateParm:
62  case Decl::ObjCMethod:
63  case Decl::ObjCCategory:
64  case Decl::ObjCProtocol:
65  case Decl::ObjCInterface:
66  case Decl::ObjCCategoryImpl:
67  case Decl::ObjCImplementation:
68  case Decl::ObjCProperty:
69  case Decl::ObjCCompatibleAlias:
70  case Decl::AccessSpec:
71  case Decl::LinkageSpec:
72  case Decl::ObjCPropertyImpl:
73  case Decl::FileScopeAsm:
74  case Decl::Friend:
75  case Decl::FriendTemplate:
76  case Decl::Block:
77  case Decl::Captured:
78  case Decl::ClassScopeFunctionSpecialization:
79  case Decl::UsingShadow:
80    llvm_unreachable("Declaration should not be in declstmts!");
81  case Decl::Function:  // void X();
82  case Decl::Record:    // struct/union/class X;
83  case Decl::Enum:      // enum X;
84  case Decl::EnumConstant: // enum ? { X = ? }
85  case Decl::CXXRecord: // struct/union/class X; [C++]
86  case Decl::StaticAssert: // static_assert(X, ""); [C++0x]
87  case Decl::Label:        // __label__ x;
88  case Decl::Import:
89  case Decl::OMPThreadPrivate:
90  case Decl::Empty:
91    // None of these decls require codegen support.
92    return;
93
94  case Decl::NamespaceAlias:
95    if (CGDebugInfo *DI = getDebugInfo())
96        DI->EmitNamespaceAlias(cast<NamespaceAliasDecl>(D));
97    return;
98  case Decl::Using:          // using X; [C++]
99    if (CGDebugInfo *DI = getDebugInfo())
100        DI->EmitUsingDecl(cast<UsingDecl>(D));
101    return;
102  case Decl::UsingDirective: // using namespace X; [C++]
103    if (CGDebugInfo *DI = getDebugInfo())
104      DI->EmitUsingDirective(cast<UsingDirectiveDecl>(D));
105    return;
106  case Decl::Var: {
107    const VarDecl &VD = cast<VarDecl>(D);
108    assert(VD.isLocalVarDecl() &&
109           "Should not see file-scope variables inside a function!");
110    return EmitVarDecl(VD);
111  }
112
113  case Decl::Typedef:      // typedef int X;
114  case Decl::TypeAlias: {  // using X = int; [C++0x]
115    const TypedefNameDecl &TD = cast<TypedefNameDecl>(D);
116    QualType Ty = TD.getUnderlyingType();
117
118    if (Ty->isVariablyModifiedType())
119      EmitVariablyModifiedType(Ty);
120  }
121  }
122}
123
124/// EmitVarDecl - This method handles emission of any variable declaration
125/// inside a function, including static vars etc.
126void CodeGenFunction::EmitVarDecl(const VarDecl &D) {
127  if (D.isStaticLocal()) {
128    llvm::GlobalValue::LinkageTypes Linkage =
129        CGM.getLLVMLinkageVarDefinition(&D, /*isConstant=*/false);
130
131    // FIXME: We need to force the emission/use of a guard variable for
132    // some variables even if we can constant-evaluate them because
133    // we can't guarantee every translation unit will constant-evaluate them.
134
135    return EmitStaticVarDecl(D, Linkage);
136  }
137
138  if (D.hasExternalStorage())
139    // Don't emit it now, allow it to be emitted lazily on its first use.
140    return;
141
142  if (D.getStorageClass() == SC_OpenCLWorkGroupLocal)
143    return CGM.getOpenCLRuntime().EmitWorkGroupLocalVarDecl(*this, D);
144
145  assert(D.hasLocalStorage());
146  return EmitAutoVarDecl(D);
147}
148
149static std::string GetStaticDeclName(CodeGenFunction &CGF, const VarDecl &D,
150                                     const char *Separator) {
151  CodeGenModule &CGM = CGF.CGM;
152
153  if (CGF.getLangOpts().CPlusPlus)
154    return CGM.getMangledName(&D).str();
155
156  StringRef ContextName;
157  if (!CGF.CurFuncDecl) {
158    // Better be in a block declared in global scope.
159    const NamedDecl *ND = cast<NamedDecl>(&D);
160    const DeclContext *DC = ND->getDeclContext();
161    if (const BlockDecl *BD = dyn_cast<BlockDecl>(DC))
162      ContextName = CGM.getBlockMangledName(GlobalDecl(), BD);
163    else
164      llvm_unreachable("Unknown context for block static var decl");
165  } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CGF.CurFuncDecl))
166    ContextName = CGM.getMangledName(FD);
167  else if (isa<ObjCMethodDecl>(CGF.CurFuncDecl))
168    ContextName = CGF.CurFn->getName();
169  else
170    llvm_unreachable("Unknown context for static var decl");
171
172  return ContextName.str() + Separator + D.getNameAsString();
173}
174
175llvm::Constant *
176CodeGenFunction::CreateStaticVarDecl(const VarDecl &D,
177                                     const char *Separator,
178                                     llvm::GlobalValue::LinkageTypes Linkage) {
179  QualType Ty = D.getType();
180  assert(Ty->isConstantSizeType() && "VLAs can't be static");
181
182  // Use the label if the variable is renamed with the asm-label extension.
183  std::string Name;
184  if (D.hasAttr<AsmLabelAttr>())
185    Name = CGM.getMangledName(&D);
186  else
187    Name = GetStaticDeclName(*this, D, Separator);
188
189  llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(Ty);
190  unsigned AddrSpace =
191   CGM.GetGlobalVarAddressSpace(&D, CGM.getContext().getTargetAddressSpace(Ty));
192  llvm::GlobalVariable *GV =
193    new llvm::GlobalVariable(CGM.getModule(), LTy,
194                             Ty.isConstant(getContext()), Linkage,
195                             CGM.EmitNullConstant(D.getType()), Name, nullptr,
196                             llvm::GlobalVariable::NotThreadLocal,
197                             AddrSpace);
198  GV->setAlignment(getContext().getDeclAlign(&D).getQuantity());
199  CGM.setGlobalVisibility(GV, &D);
200
201  if (D.getTLSKind())
202    CGM.setTLSMode(GV, D);
203
204  if (D.isExternallyVisible()) {
205    if (D.hasAttr<DLLImportAttr>())
206      GV->setDLLStorageClass(llvm::GlobalVariable::DLLImportStorageClass);
207    else if (D.hasAttr<DLLExportAttr>())
208      GV->setDLLStorageClass(llvm::GlobalVariable::DLLExportStorageClass);
209  }
210
211  // Make sure the result is of the correct type.
212  unsigned ExpectedAddrSpace = CGM.getContext().getTargetAddressSpace(Ty);
213  if (AddrSpace != ExpectedAddrSpace) {
214    llvm::PointerType *PTy = llvm::PointerType::get(LTy, ExpectedAddrSpace);
215    return llvm::ConstantExpr::getAddrSpaceCast(GV, PTy);
216  }
217
218  return GV;
219}
220
221/// hasNontrivialDestruction - Determine whether a type's destruction is
222/// non-trivial. If so, and the variable uses static initialization, we must
223/// register its destructor to run on exit.
224static bool hasNontrivialDestruction(QualType T) {
225  CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
226  return RD && !RD->hasTrivialDestructor();
227}
228
229/// AddInitializerToStaticVarDecl - Add the initializer for 'D' to the
230/// global variable that has already been created for it.  If the initializer
231/// has a different type than GV does, this may free GV and return a different
232/// one.  Otherwise it just returns GV.
233llvm::GlobalVariable *
234CodeGenFunction::AddInitializerToStaticVarDecl(const VarDecl &D,
235                                               llvm::GlobalVariable *GV) {
236  llvm::Constant *Init = CGM.EmitConstantInit(D, this);
237
238  // If constant emission failed, then this should be a C++ static
239  // initializer.
240  if (!Init) {
241    if (!getLangOpts().CPlusPlus)
242      CGM.ErrorUnsupported(D.getInit(), "constant l-value expression");
243    else if (Builder.GetInsertBlock()) {
244      // Since we have a static initializer, this global variable can't
245      // be constant.
246      GV->setConstant(false);
247
248      EmitCXXGuardedInit(D, GV, /*PerformInit*/true);
249    }
250    return GV;
251  }
252
253  // The initializer may differ in type from the global. Rewrite
254  // the global to match the initializer.  (We have to do this
255  // because some types, like unions, can't be completely represented
256  // in the LLVM type system.)
257  if (GV->getType()->getElementType() != Init->getType()) {
258    llvm::GlobalVariable *OldGV = GV;
259
260    GV = new llvm::GlobalVariable(CGM.getModule(), Init->getType(),
261                                  OldGV->isConstant(),
262                                  OldGV->getLinkage(), Init, "",
263                                  /*InsertBefore*/ OldGV,
264                                  OldGV->getThreadLocalMode(),
265                           CGM.getContext().getTargetAddressSpace(D.getType()));
266    GV->setVisibility(OldGV->getVisibility());
267
268    // Steal the name of the old global
269    GV->takeName(OldGV);
270
271    // Replace all uses of the old global with the new global
272    llvm::Constant *NewPtrForOldDecl =
273    llvm::ConstantExpr::getBitCast(GV, OldGV->getType());
274    OldGV->replaceAllUsesWith(NewPtrForOldDecl);
275
276    // Erase the old global, since it is no longer used.
277    OldGV->eraseFromParent();
278  }
279
280  GV->setConstant(CGM.isTypeConstant(D.getType(), true));
281  GV->setInitializer(Init);
282
283  if (hasNontrivialDestruction(D.getType())) {
284    // We have a constant initializer, but a nontrivial destructor. We still
285    // need to perform a guarded "initialization" in order to register the
286    // destructor.
287    EmitCXXGuardedInit(D, GV, /*PerformInit*/false);
288  }
289
290  return GV;
291}
292
293void CodeGenFunction::EmitStaticVarDecl(const VarDecl &D,
294                                      llvm::GlobalValue::LinkageTypes Linkage) {
295  llvm::Value *&DMEntry = LocalDeclMap[&D];
296  assert(!DMEntry && "Decl already exists in localdeclmap!");
297
298  // Check to see if we already have a global variable for this
299  // declaration.  This can happen when double-emitting function
300  // bodies, e.g. with complete and base constructors.
301  llvm::Constant *addr =
302    CGM.getStaticLocalDeclAddress(&D);
303
304  if (!addr)
305    addr = CreateStaticVarDecl(D, ".", Linkage);
306
307  // Store into LocalDeclMap before generating initializer to handle
308  // circular references.
309  DMEntry = addr;
310  CGM.setStaticLocalDeclAddress(&D, addr);
311
312  // We can't have a VLA here, but we can have a pointer to a VLA,
313  // even though that doesn't really make any sense.
314  // Make sure to evaluate VLA bounds now so that we have them for later.
315  if (D.getType()->isVariablyModifiedType())
316    EmitVariablyModifiedType(D.getType());
317
318  // Save the type in case adding the initializer forces a type change.
319  llvm::Type *expectedType = addr->getType();
320
321  llvm::GlobalVariable *var =
322    cast<llvm::GlobalVariable>(addr->stripPointerCasts());
323  // If this value has an initializer, emit it.
324  if (D.getInit())
325    var = AddInitializerToStaticVarDecl(D, var);
326
327  var->setAlignment(getContext().getDeclAlign(&D).getQuantity());
328
329  if (D.hasAttr<AnnotateAttr>())
330    CGM.AddGlobalAnnotations(&D, var);
331
332  if (const SectionAttr *SA = D.getAttr<SectionAttr>())
333    var->setSection(SA->getName());
334
335  if (D.hasAttr<UsedAttr>())
336    CGM.addUsedGlobal(var);
337
338  // We may have to cast the constant because of the initializer
339  // mismatch above.
340  //
341  // FIXME: It is really dangerous to store this in the map; if anyone
342  // RAUW's the GV uses of this constant will be invalid.
343  llvm::Constant *castedAddr =
344    llvm::ConstantExpr::getPointerBitCastOrAddrSpaceCast(var, expectedType);
345  DMEntry = castedAddr;
346  CGM.setStaticLocalDeclAddress(&D, castedAddr);
347
348  CGM.reportGlobalToASan(var, D.getLocation());
349
350  // Emit global variable debug descriptor for static vars.
351  CGDebugInfo *DI = getDebugInfo();
352  if (DI &&
353      CGM.getCodeGenOpts().getDebugInfo() >= CodeGenOptions::LimitedDebugInfo) {
354    DI->setLocation(D.getLocation());
355    DI->EmitGlobalVariable(var, &D);
356  }
357}
358
359namespace {
360  struct DestroyObject : EHScopeStack::Cleanup {
361    DestroyObject(llvm::Value *addr, QualType type,
362                  CodeGenFunction::Destroyer *destroyer,
363                  bool useEHCleanupForArray)
364      : addr(addr), type(type), destroyer(destroyer),
365        useEHCleanupForArray(useEHCleanupForArray) {}
366
367    llvm::Value *addr;
368    QualType type;
369    CodeGenFunction::Destroyer *destroyer;
370    bool useEHCleanupForArray;
371
372    void Emit(CodeGenFunction &CGF, Flags flags) override {
373      // Don't use an EH cleanup recursively from an EH cleanup.
374      bool useEHCleanupForArray =
375        flags.isForNormalCleanup() && this->useEHCleanupForArray;
376
377      CGF.emitDestroy(addr, type, destroyer, useEHCleanupForArray);
378    }
379  };
380
381  struct DestroyNRVOVariable : EHScopeStack::Cleanup {
382    DestroyNRVOVariable(llvm::Value *addr,
383                        const CXXDestructorDecl *Dtor,
384                        llvm::Value *NRVOFlag)
385      : Dtor(Dtor), NRVOFlag(NRVOFlag), Loc(addr) {}
386
387    const CXXDestructorDecl *Dtor;
388    llvm::Value *NRVOFlag;
389    llvm::Value *Loc;
390
391    void Emit(CodeGenFunction &CGF, Flags flags) override {
392      // Along the exceptions path we always execute the dtor.
393      bool NRVO = flags.isForNormalCleanup() && NRVOFlag;
394
395      llvm::BasicBlock *SkipDtorBB = nullptr;
396      if (NRVO) {
397        // If we exited via NRVO, we skip the destructor call.
398        llvm::BasicBlock *RunDtorBB = CGF.createBasicBlock("nrvo.unused");
399        SkipDtorBB = CGF.createBasicBlock("nrvo.skipdtor");
400        llvm::Value *DidNRVO = CGF.Builder.CreateLoad(NRVOFlag, "nrvo.val");
401        CGF.Builder.CreateCondBr(DidNRVO, SkipDtorBB, RunDtorBB);
402        CGF.EmitBlock(RunDtorBB);
403      }
404
405      CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
406                                /*ForVirtualBase=*/false,
407                                /*Delegating=*/false,
408                                Loc);
409
410      if (NRVO) CGF.EmitBlock(SkipDtorBB);
411    }
412  };
413
414  struct CallStackRestore : EHScopeStack::Cleanup {
415    llvm::Value *Stack;
416    CallStackRestore(llvm::Value *Stack) : Stack(Stack) {}
417    void Emit(CodeGenFunction &CGF, Flags flags) override {
418      llvm::Value *V = CGF.Builder.CreateLoad(Stack);
419      llvm::Value *F = CGF.CGM.getIntrinsic(llvm::Intrinsic::stackrestore);
420      CGF.Builder.CreateCall(F, V);
421    }
422  };
423
424  struct ExtendGCLifetime : EHScopeStack::Cleanup {
425    const VarDecl &Var;
426    ExtendGCLifetime(const VarDecl *var) : Var(*var) {}
427
428    void Emit(CodeGenFunction &CGF, Flags flags) override {
429      // Compute the address of the local variable, in case it's a
430      // byref or something.
431      DeclRefExpr DRE(const_cast<VarDecl*>(&Var), false,
432                      Var.getType(), VK_LValue, SourceLocation());
433      llvm::Value *value = CGF.EmitLoadOfScalar(CGF.EmitDeclRefLValue(&DRE),
434                                                SourceLocation());
435      CGF.EmitExtendGCLifetime(value);
436    }
437  };
438
439  struct CallCleanupFunction : EHScopeStack::Cleanup {
440    llvm::Constant *CleanupFn;
441    const CGFunctionInfo &FnInfo;
442    const VarDecl &Var;
443
444    CallCleanupFunction(llvm::Constant *CleanupFn, const CGFunctionInfo *Info,
445                        const VarDecl *Var)
446      : CleanupFn(CleanupFn), FnInfo(*Info), Var(*Var) {}
447
448    void Emit(CodeGenFunction &CGF, Flags flags) override {
449      DeclRefExpr DRE(const_cast<VarDecl*>(&Var), false,
450                      Var.getType(), VK_LValue, SourceLocation());
451      // Compute the address of the local variable, in case it's a byref
452      // or something.
453      llvm::Value *Addr = CGF.EmitDeclRefLValue(&DRE).getAddress();
454
455      // In some cases, the type of the function argument will be different from
456      // the type of the pointer. An example of this is
457      // void f(void* arg);
458      // __attribute__((cleanup(f))) void *g;
459      //
460      // To fix this we insert a bitcast here.
461      QualType ArgTy = FnInfo.arg_begin()->type;
462      llvm::Value *Arg =
463        CGF.Builder.CreateBitCast(Addr, CGF.ConvertType(ArgTy));
464
465      CallArgList Args;
466      Args.add(RValue::get(Arg),
467               CGF.getContext().getPointerType(Var.getType()));
468      CGF.EmitCall(FnInfo, CleanupFn, ReturnValueSlot(), Args);
469    }
470  };
471
472  /// A cleanup to call @llvm.lifetime.end.
473  class CallLifetimeEnd : public EHScopeStack::Cleanup {
474    llvm::Value *Addr;
475    llvm::Value *Size;
476  public:
477    CallLifetimeEnd(llvm::Value *addr, llvm::Value *size)
478      : Addr(addr), Size(size) {}
479
480    void Emit(CodeGenFunction &CGF, Flags flags) override {
481      llvm::Value *castAddr = CGF.Builder.CreateBitCast(Addr, CGF.Int8PtrTy);
482      CGF.Builder.CreateCall2(CGF.CGM.getLLVMLifetimeEndFn(),
483                              Size, castAddr)
484        ->setDoesNotThrow();
485    }
486  };
487}
488
489/// EmitAutoVarWithLifetime - Does the setup required for an automatic
490/// variable with lifetime.
491static void EmitAutoVarWithLifetime(CodeGenFunction &CGF, const VarDecl &var,
492                                    llvm::Value *addr,
493                                    Qualifiers::ObjCLifetime lifetime) {
494  switch (lifetime) {
495  case Qualifiers::OCL_None:
496    llvm_unreachable("present but none");
497
498  case Qualifiers::OCL_ExplicitNone:
499    // nothing to do
500    break;
501
502  case Qualifiers::OCL_Strong: {
503    CodeGenFunction::Destroyer *destroyer =
504      (var.hasAttr<ObjCPreciseLifetimeAttr>()
505       ? CodeGenFunction::destroyARCStrongPrecise
506       : CodeGenFunction::destroyARCStrongImprecise);
507
508    CleanupKind cleanupKind = CGF.getARCCleanupKind();
509    CGF.pushDestroy(cleanupKind, addr, var.getType(), destroyer,
510                    cleanupKind & EHCleanup);
511    break;
512  }
513  case Qualifiers::OCL_Autoreleasing:
514    // nothing to do
515    break;
516
517  case Qualifiers::OCL_Weak:
518    // __weak objects always get EH cleanups; otherwise, exceptions
519    // could cause really nasty crashes instead of mere leaks.
520    CGF.pushDestroy(NormalAndEHCleanup, addr, var.getType(),
521                    CodeGenFunction::destroyARCWeak,
522                    /*useEHCleanup*/ true);
523    break;
524  }
525}
526
527static bool isAccessedBy(const VarDecl &var, const Stmt *s) {
528  if (const Expr *e = dyn_cast<Expr>(s)) {
529    // Skip the most common kinds of expressions that make
530    // hierarchy-walking expensive.
531    s = e = e->IgnoreParenCasts();
532
533    if (const DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e))
534      return (ref->getDecl() == &var);
535    if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) {
536      const BlockDecl *block = be->getBlockDecl();
537      for (const auto &I : block->captures()) {
538        if (I.getVariable() == &var)
539          return true;
540      }
541    }
542  }
543
544  for (Stmt::const_child_range children = s->children(); children; ++children)
545    // children might be null; as in missing decl or conditional of an if-stmt.
546    if ((*children) && isAccessedBy(var, *children))
547      return true;
548
549  return false;
550}
551
552static bool isAccessedBy(const ValueDecl *decl, const Expr *e) {
553  if (!decl) return false;
554  if (!isa<VarDecl>(decl)) return false;
555  const VarDecl *var = cast<VarDecl>(decl);
556  return isAccessedBy(*var, e);
557}
558
559static void drillIntoBlockVariable(CodeGenFunction &CGF,
560                                   LValue &lvalue,
561                                   const VarDecl *var) {
562  lvalue.setAddress(CGF.BuildBlockByrefAddress(lvalue.getAddress(), var));
563}
564
565void CodeGenFunction::EmitScalarInit(const Expr *init,
566                                     const ValueDecl *D,
567                                     LValue lvalue,
568                                     bool capturedByInit) {
569  Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
570  if (!lifetime) {
571    llvm::Value *value = EmitScalarExpr(init);
572    if (capturedByInit)
573      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
574    EmitStoreThroughLValue(RValue::get(value), lvalue, true);
575    return;
576  }
577
578  if (const CXXDefaultInitExpr *DIE = dyn_cast<CXXDefaultInitExpr>(init))
579    init = DIE->getExpr();
580
581  // If we're emitting a value with lifetime, we have to do the
582  // initialization *before* we leave the cleanup scopes.
583  if (const ExprWithCleanups *ewc = dyn_cast<ExprWithCleanups>(init)) {
584    enterFullExpression(ewc);
585    init = ewc->getSubExpr();
586  }
587  CodeGenFunction::RunCleanupsScope Scope(*this);
588
589  // We have to maintain the illusion that the variable is
590  // zero-initialized.  If the variable might be accessed in its
591  // initializer, zero-initialize before running the initializer, then
592  // actually perform the initialization with an assign.
593  bool accessedByInit = false;
594  if (lifetime != Qualifiers::OCL_ExplicitNone)
595    accessedByInit = (capturedByInit || isAccessedBy(D, init));
596  if (accessedByInit) {
597    LValue tempLV = lvalue;
598    // Drill down to the __block object if necessary.
599    if (capturedByInit) {
600      // We can use a simple GEP for this because it can't have been
601      // moved yet.
602      tempLV.setAddress(Builder.CreateStructGEP(tempLV.getAddress(),
603                                   getByRefValueLLVMField(cast<VarDecl>(D))));
604    }
605
606    llvm::PointerType *ty
607      = cast<llvm::PointerType>(tempLV.getAddress()->getType());
608    ty = cast<llvm::PointerType>(ty->getElementType());
609
610    llvm::Value *zero = llvm::ConstantPointerNull::get(ty);
611
612    // If __weak, we want to use a barrier under certain conditions.
613    if (lifetime == Qualifiers::OCL_Weak)
614      EmitARCInitWeak(tempLV.getAddress(), zero);
615
616    // Otherwise just do a simple store.
617    else
618      EmitStoreOfScalar(zero, tempLV, /* isInitialization */ true);
619  }
620
621  // Emit the initializer.
622  llvm::Value *value = nullptr;
623
624  switch (lifetime) {
625  case Qualifiers::OCL_None:
626    llvm_unreachable("present but none");
627
628  case Qualifiers::OCL_ExplicitNone:
629    // nothing to do
630    value = EmitScalarExpr(init);
631    break;
632
633  case Qualifiers::OCL_Strong: {
634    value = EmitARCRetainScalarExpr(init);
635    break;
636  }
637
638  case Qualifiers::OCL_Weak: {
639    // No way to optimize a producing initializer into this.  It's not
640    // worth optimizing for, because the value will immediately
641    // disappear in the common case.
642    value = EmitScalarExpr(init);
643
644    if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
645    if (accessedByInit)
646      EmitARCStoreWeak(lvalue.getAddress(), value, /*ignored*/ true);
647    else
648      EmitARCInitWeak(lvalue.getAddress(), value);
649    return;
650  }
651
652  case Qualifiers::OCL_Autoreleasing:
653    value = EmitARCRetainAutoreleaseScalarExpr(init);
654    break;
655  }
656
657  if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
658
659  // If the variable might have been accessed by its initializer, we
660  // might have to initialize with a barrier.  We have to do this for
661  // both __weak and __strong, but __weak got filtered out above.
662  if (accessedByInit && lifetime == Qualifiers::OCL_Strong) {
663    llvm::Value *oldValue = EmitLoadOfScalar(lvalue, init->getExprLoc());
664    EmitStoreOfScalar(value, lvalue, /* isInitialization */ true);
665    EmitARCRelease(oldValue, ARCImpreciseLifetime);
666    return;
667  }
668
669  EmitStoreOfScalar(value, lvalue, /* isInitialization */ true);
670}
671
672/// EmitScalarInit - Initialize the given lvalue with the given object.
673void CodeGenFunction::EmitScalarInit(llvm::Value *init, LValue lvalue) {
674  Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
675  if (!lifetime)
676    return EmitStoreThroughLValue(RValue::get(init), lvalue, true);
677
678  switch (lifetime) {
679  case Qualifiers::OCL_None:
680    llvm_unreachable("present but none");
681
682  case Qualifiers::OCL_ExplicitNone:
683    // nothing to do
684    break;
685
686  case Qualifiers::OCL_Strong:
687    init = EmitARCRetain(lvalue.getType(), init);
688    break;
689
690  case Qualifiers::OCL_Weak:
691    // Initialize and then skip the primitive store.
692    EmitARCInitWeak(lvalue.getAddress(), init);
693    return;
694
695  case Qualifiers::OCL_Autoreleasing:
696    init = EmitARCRetainAutorelease(lvalue.getType(), init);
697    break;
698  }
699
700  EmitStoreOfScalar(init, lvalue, /* isInitialization */ true);
701}
702
703/// canEmitInitWithFewStoresAfterMemset - Decide whether we can emit the
704/// non-zero parts of the specified initializer with equal or fewer than
705/// NumStores scalar stores.
706static bool canEmitInitWithFewStoresAfterMemset(llvm::Constant *Init,
707                                                unsigned &NumStores) {
708  // Zero and Undef never requires any extra stores.
709  if (isa<llvm::ConstantAggregateZero>(Init) ||
710      isa<llvm::ConstantPointerNull>(Init) ||
711      isa<llvm::UndefValue>(Init))
712    return true;
713  if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
714      isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
715      isa<llvm::ConstantExpr>(Init))
716    return Init->isNullValue() || NumStores--;
717
718  // See if we can emit each element.
719  if (isa<llvm::ConstantArray>(Init) || isa<llvm::ConstantStruct>(Init)) {
720    for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
721      llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
722      if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores))
723        return false;
724    }
725    return true;
726  }
727
728  if (llvm::ConstantDataSequential *CDS =
729        dyn_cast<llvm::ConstantDataSequential>(Init)) {
730    for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
731      llvm::Constant *Elt = CDS->getElementAsConstant(i);
732      if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores))
733        return false;
734    }
735    return true;
736  }
737
738  // Anything else is hard and scary.
739  return false;
740}
741
742/// emitStoresForInitAfterMemset - For inits that
743/// canEmitInitWithFewStoresAfterMemset returned true for, emit the scalar
744/// stores that would be required.
745static void emitStoresForInitAfterMemset(llvm::Constant *Init, llvm::Value *Loc,
746                                         bool isVolatile, CGBuilderTy &Builder) {
747  assert(!Init->isNullValue() && !isa<llvm::UndefValue>(Init) &&
748         "called emitStoresForInitAfterMemset for zero or undef value.");
749
750  if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
751      isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
752      isa<llvm::ConstantExpr>(Init)) {
753    Builder.CreateStore(Init, Loc, isVolatile);
754    return;
755  }
756
757  if (llvm::ConstantDataSequential *CDS =
758        dyn_cast<llvm::ConstantDataSequential>(Init)) {
759    for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
760      llvm::Constant *Elt = CDS->getElementAsConstant(i);
761
762      // If necessary, get a pointer to the element and emit it.
763      if (!Elt->isNullValue() && !isa<llvm::UndefValue>(Elt))
764        emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i),
765                                     isVolatile, Builder);
766    }
767    return;
768  }
769
770  assert((isa<llvm::ConstantStruct>(Init) || isa<llvm::ConstantArray>(Init)) &&
771         "Unknown value type!");
772
773  for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
774    llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
775
776    // If necessary, get a pointer to the element and emit it.
777    if (!Elt->isNullValue() && !isa<llvm::UndefValue>(Elt))
778      emitStoresForInitAfterMemset(Elt, Builder.CreateConstGEP2_32(Loc, 0, i),
779                                   isVolatile, Builder);
780  }
781}
782
783
784/// shouldUseMemSetPlusStoresToInitialize - Decide whether we should use memset
785/// plus some stores to initialize a local variable instead of using a memcpy
786/// from a constant global.  It is beneficial to use memset if the global is all
787/// zeros, or mostly zeros and large.
788static bool shouldUseMemSetPlusStoresToInitialize(llvm::Constant *Init,
789                                                  uint64_t GlobalSize) {
790  // If a global is all zeros, always use a memset.
791  if (isa<llvm::ConstantAggregateZero>(Init)) return true;
792
793  // If a non-zero global is <= 32 bytes, always use a memcpy.  If it is large,
794  // do it if it will require 6 or fewer scalar stores.
795  // TODO: Should budget depends on the size?  Avoiding a large global warrants
796  // plopping in more stores.
797  unsigned StoreBudget = 6;
798  uint64_t SizeLimit = 32;
799
800  return GlobalSize > SizeLimit &&
801         canEmitInitWithFewStoresAfterMemset(Init, StoreBudget);
802}
803
804/// Should we use the LLVM lifetime intrinsics for the given local variable?
805static bool shouldUseLifetimeMarkers(CodeGenFunction &CGF, const VarDecl &D,
806                                     unsigned Size) {
807  // For now, only in optimized builds.
808  if (CGF.CGM.getCodeGenOpts().OptimizationLevel == 0)
809    return false;
810
811  // Limit the size of marked objects to 32 bytes. We don't want to increase
812  // compile time by marking tiny objects.
813  unsigned SizeThreshold = 32;
814
815  return Size > SizeThreshold;
816}
817
818
819/// EmitAutoVarDecl - Emit code and set up an entry in LocalDeclMap for a
820/// variable declaration with auto, register, or no storage class specifier.
821/// These turn into simple stack objects, or GlobalValues depending on target.
822void CodeGenFunction::EmitAutoVarDecl(const VarDecl &D) {
823  AutoVarEmission emission = EmitAutoVarAlloca(D);
824  EmitAutoVarInit(emission);
825  EmitAutoVarCleanups(emission);
826}
827
828/// EmitAutoVarAlloca - Emit the alloca and debug information for a
829/// local variable.  Does not emit initialization or destruction.
830CodeGenFunction::AutoVarEmission
831CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) {
832  QualType Ty = D.getType();
833
834  AutoVarEmission emission(D);
835
836  bool isByRef = D.hasAttr<BlocksAttr>();
837  emission.IsByRef = isByRef;
838
839  CharUnits alignment = getContext().getDeclAlign(&D);
840  emission.Alignment = alignment;
841
842  // If the type is variably-modified, emit all the VLA sizes for it.
843  if (Ty->isVariablyModifiedType())
844    EmitVariablyModifiedType(Ty);
845
846  llvm::Value *DeclPtr;
847  if (Ty->isConstantSizeType()) {
848    bool NRVO = getLangOpts().ElideConstructors &&
849      D.isNRVOVariable();
850
851    // If this value is an array or struct with a statically determinable
852    // constant initializer, there are optimizations we can do.
853    //
854    // TODO: We should constant-evaluate the initializer of any variable,
855    // as long as it is initialized by a constant expression. Currently,
856    // isConstantInitializer produces wrong answers for structs with
857    // reference or bitfield members, and a few other cases, and checking
858    // for POD-ness protects us from some of these.
859    if (D.getInit() && (Ty->isArrayType() || Ty->isRecordType()) &&
860        (D.isConstexpr() ||
861         ((Ty.isPODType(getContext()) ||
862           getContext().getBaseElementType(Ty)->isObjCObjectPointerType()) &&
863          D.getInit()->isConstantInitializer(getContext(), false)))) {
864
865      // If the variable's a const type, and it's neither an NRVO
866      // candidate nor a __block variable and has no mutable members,
867      // emit it as a global instead.
868      if (CGM.getCodeGenOpts().MergeAllConstants && !NRVO && !isByRef &&
869          CGM.isTypeConstant(Ty, true)) {
870        EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage);
871
872        emission.Address = nullptr; // signal this condition to later callbacks
873        assert(emission.wasEmittedAsGlobal());
874        return emission;
875      }
876
877      // Otherwise, tell the initialization code that we're in this case.
878      emission.IsConstantAggregate = true;
879    }
880
881    // A normal fixed sized variable becomes an alloca in the entry block,
882    // unless it's an NRVO variable.
883    llvm::Type *LTy = ConvertTypeForMem(Ty);
884
885    if (NRVO) {
886      // The named return value optimization: allocate this variable in the
887      // return slot, so that we can elide the copy when returning this
888      // variable (C++0x [class.copy]p34).
889      DeclPtr = ReturnValue;
890
891      if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
892        if (!cast<CXXRecordDecl>(RecordTy->getDecl())->hasTrivialDestructor()) {
893          // Create a flag that is used to indicate when the NRVO was applied
894          // to this variable. Set it to zero to indicate that NRVO was not
895          // applied.
896          llvm::Value *Zero = Builder.getFalse();
897          llvm::Value *NRVOFlag = CreateTempAlloca(Zero->getType(), "nrvo");
898          EnsureInsertPoint();
899          Builder.CreateStore(Zero, NRVOFlag);
900
901          // Record the NRVO flag for this variable.
902          NRVOFlags[&D] = NRVOFlag;
903          emission.NRVOFlag = NRVOFlag;
904        }
905      }
906    } else {
907      if (isByRef)
908        LTy = BuildByRefType(&D);
909
910      llvm::AllocaInst *Alloc = CreateTempAlloca(LTy);
911      Alloc->setName(D.getName());
912
913      CharUnits allocaAlignment = alignment;
914      if (isByRef)
915        allocaAlignment = std::max(allocaAlignment,
916            getContext().toCharUnitsFromBits(getTarget().getPointerAlign(0)));
917      Alloc->setAlignment(allocaAlignment.getQuantity());
918      DeclPtr = Alloc;
919
920      // Emit a lifetime intrinsic if meaningful.  There's no point
921      // in doing this if we don't have a valid insertion point (?).
922      uint64_t size = CGM.getDataLayout().getTypeAllocSize(LTy);
923      if (HaveInsertPoint() && shouldUseLifetimeMarkers(*this, D, size)) {
924        llvm::Value *sizeV = llvm::ConstantInt::get(Int64Ty, size);
925
926        emission.SizeForLifetimeMarkers = sizeV;
927        llvm::Value *castAddr = Builder.CreateBitCast(Alloc, Int8PtrTy);
928        Builder.CreateCall2(CGM.getLLVMLifetimeStartFn(), sizeV, castAddr)
929          ->setDoesNotThrow();
930      } else {
931        assert(!emission.useLifetimeMarkers());
932      }
933    }
934  } else {
935    EnsureInsertPoint();
936
937    if (!DidCallStackSave) {
938      // Save the stack.
939      llvm::Value *Stack = CreateTempAlloca(Int8PtrTy, "saved_stack");
940
941      llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave);
942      llvm::Value *V = Builder.CreateCall(F);
943
944      Builder.CreateStore(V, Stack);
945
946      DidCallStackSave = true;
947
948      // Push a cleanup block and restore the stack there.
949      // FIXME: in general circumstances, this should be an EH cleanup.
950      pushStackRestore(NormalCleanup, Stack);
951    }
952
953    llvm::Value *elementCount;
954    QualType elementType;
955    std::tie(elementCount, elementType) = getVLASize(Ty);
956
957    llvm::Type *llvmTy = ConvertTypeForMem(elementType);
958
959    // Allocate memory for the array.
960    llvm::AllocaInst *vla = Builder.CreateAlloca(llvmTy, elementCount, "vla");
961    vla->setAlignment(alignment.getQuantity());
962
963    DeclPtr = vla;
964  }
965
966  llvm::Value *&DMEntry = LocalDeclMap[&D];
967  assert(!DMEntry && "Decl already exists in localdeclmap!");
968  DMEntry = DeclPtr;
969  emission.Address = DeclPtr;
970
971  // Emit debug info for local var declaration.
972  if (HaveInsertPoint())
973    if (CGDebugInfo *DI = getDebugInfo()) {
974      if (CGM.getCodeGenOpts().getDebugInfo()
975            >= CodeGenOptions::LimitedDebugInfo) {
976        DI->setLocation(D.getLocation());
977        DI->EmitDeclareOfAutoVariable(&D, DeclPtr, Builder);
978      }
979    }
980
981  if (D.hasAttr<AnnotateAttr>())
982      EmitVarAnnotations(&D, emission.Address);
983
984  return emission;
985}
986
987/// Determines whether the given __block variable is potentially
988/// captured by the given expression.
989static bool isCapturedBy(const VarDecl &var, const Expr *e) {
990  // Skip the most common kinds of expressions that make
991  // hierarchy-walking expensive.
992  e = e->IgnoreParenCasts();
993
994  if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) {
995    const BlockDecl *block = be->getBlockDecl();
996    for (const auto &I : block->captures()) {
997      if (I.getVariable() == &var)
998        return true;
999    }
1000
1001    // No need to walk into the subexpressions.
1002    return false;
1003  }
1004
1005  if (const StmtExpr *SE = dyn_cast<StmtExpr>(e)) {
1006    const CompoundStmt *CS = SE->getSubStmt();
1007    for (const auto *BI : CS->body())
1008      if (const auto *E = dyn_cast<Expr>(BI)) {
1009        if (isCapturedBy(var, E))
1010            return true;
1011      }
1012      else if (const auto *DS = dyn_cast<DeclStmt>(BI)) {
1013          // special case declarations
1014          for (const auto *I : DS->decls()) {
1015              if (const auto *VD = dyn_cast<VarDecl>((I))) {
1016                const Expr *Init = VD->getInit();
1017                if (Init && isCapturedBy(var, Init))
1018                  return true;
1019              }
1020          }
1021      }
1022      else
1023        // FIXME. Make safe assumption assuming arbitrary statements cause capturing.
1024        // Later, provide code to poke into statements for capture analysis.
1025        return true;
1026    return false;
1027  }
1028
1029  for (Stmt::const_child_range children = e->children(); children; ++children)
1030    if (isCapturedBy(var, cast<Expr>(*children)))
1031      return true;
1032
1033  return false;
1034}
1035
1036/// \brief Determine whether the given initializer is trivial in the sense
1037/// that it requires no code to be generated.
1038static bool isTrivialInitializer(const Expr *Init) {
1039  if (!Init)
1040    return true;
1041
1042  if (const CXXConstructExpr *Construct = dyn_cast<CXXConstructExpr>(Init))
1043    if (CXXConstructorDecl *Constructor = Construct->getConstructor())
1044      if (Constructor->isTrivial() &&
1045          Constructor->isDefaultConstructor() &&
1046          !Construct->requiresZeroInitialization())
1047        return true;
1048
1049  return false;
1050}
1051void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) {
1052  assert(emission.Variable && "emission was not valid!");
1053
1054  // If this was emitted as a global constant, we're done.
1055  if (emission.wasEmittedAsGlobal()) return;
1056
1057  const VarDecl &D = *emission.Variable;
1058  QualType type = D.getType();
1059
1060  // If this local has an initializer, emit it now.
1061  const Expr *Init = D.getInit();
1062
1063  // If we are at an unreachable point, we don't need to emit the initializer
1064  // unless it contains a label.
1065  if (!HaveInsertPoint()) {
1066    if (!Init || !ContainsLabel(Init)) return;
1067    EnsureInsertPoint();
1068  }
1069
1070  // Initialize the structure of a __block variable.
1071  if (emission.IsByRef)
1072    emitByrefStructureInit(emission);
1073
1074  if (isTrivialInitializer(Init))
1075    return;
1076
1077  CharUnits alignment = emission.Alignment;
1078
1079  // Check whether this is a byref variable that's potentially
1080  // captured and moved by its own initializer.  If so, we'll need to
1081  // emit the initializer first, then copy into the variable.
1082  bool capturedByInit = emission.IsByRef && isCapturedBy(D, Init);
1083
1084  llvm::Value *Loc =
1085    capturedByInit ? emission.Address : emission.getObjectAddress(*this);
1086
1087  llvm::Constant *constant = nullptr;
1088  if (emission.IsConstantAggregate || D.isConstexpr()) {
1089    assert(!capturedByInit && "constant init contains a capturing block?");
1090    constant = CGM.EmitConstantInit(D, this);
1091  }
1092
1093  if (!constant) {
1094    LValue lv = MakeAddrLValue(Loc, type, alignment);
1095    lv.setNonGC(true);
1096    return EmitExprAsInit(Init, &D, lv, capturedByInit);
1097  }
1098
1099  if (!emission.IsConstantAggregate) {
1100    // For simple scalar/complex initialization, store the value directly.
1101    LValue lv = MakeAddrLValue(Loc, type, alignment);
1102    lv.setNonGC(true);
1103    return EmitStoreThroughLValue(RValue::get(constant), lv, true);
1104  }
1105
1106  // If this is a simple aggregate initialization, we can optimize it
1107  // in various ways.
1108  bool isVolatile = type.isVolatileQualified();
1109
1110  llvm::Value *SizeVal =
1111    llvm::ConstantInt::get(IntPtrTy,
1112                           getContext().getTypeSizeInChars(type).getQuantity());
1113
1114  llvm::Type *BP = Int8PtrTy;
1115  if (Loc->getType() != BP)
1116    Loc = Builder.CreateBitCast(Loc, BP);
1117
1118  // If the initializer is all or mostly zeros, codegen with memset then do
1119  // a few stores afterward.
1120  if (shouldUseMemSetPlusStoresToInitialize(constant,
1121                CGM.getDataLayout().getTypeAllocSize(constant->getType()))) {
1122    Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, 0), SizeVal,
1123                         alignment.getQuantity(), isVolatile);
1124    // Zero and undef don't require a stores.
1125    if (!constant->isNullValue() && !isa<llvm::UndefValue>(constant)) {
1126      Loc = Builder.CreateBitCast(Loc, constant->getType()->getPointerTo());
1127      emitStoresForInitAfterMemset(constant, Loc, isVolatile, Builder);
1128    }
1129  } else {
1130    // Otherwise, create a temporary global with the initializer then
1131    // memcpy from the global to the alloca.
1132    std::string Name = GetStaticDeclName(*this, D, ".");
1133    llvm::GlobalVariable *GV =
1134      new llvm::GlobalVariable(CGM.getModule(), constant->getType(), true,
1135                               llvm::GlobalValue::PrivateLinkage,
1136                               constant, Name);
1137    GV->setAlignment(alignment.getQuantity());
1138    GV->setUnnamedAddr(true);
1139
1140    llvm::Value *SrcPtr = GV;
1141    if (SrcPtr->getType() != BP)
1142      SrcPtr = Builder.CreateBitCast(SrcPtr, BP);
1143
1144    Builder.CreateMemCpy(Loc, SrcPtr, SizeVal, alignment.getQuantity(),
1145                         isVolatile);
1146  }
1147}
1148
1149/// Emit an expression as an initializer for a variable at the given
1150/// location.  The expression is not necessarily the normal
1151/// initializer for the variable, and the address is not necessarily
1152/// its normal location.
1153///
1154/// \param init the initializing expression
1155/// \param var the variable to act as if we're initializing
1156/// \param loc the address to initialize; its type is a pointer
1157///   to the LLVM mapping of the variable's type
1158/// \param alignment the alignment of the address
1159/// \param capturedByInit true if the variable is a __block variable
1160///   whose address is potentially changed by the initializer
1161void CodeGenFunction::EmitExprAsInit(const Expr *init,
1162                                     const ValueDecl *D,
1163                                     LValue lvalue,
1164                                     bool capturedByInit) {
1165  QualType type = D->getType();
1166
1167  if (type->isReferenceType()) {
1168    RValue rvalue = EmitReferenceBindingToExpr(init);
1169    if (capturedByInit)
1170      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
1171    EmitStoreThroughLValue(rvalue, lvalue, true);
1172    return;
1173  }
1174  switch (getEvaluationKind(type)) {
1175  case TEK_Scalar:
1176    EmitScalarInit(init, D, lvalue, capturedByInit);
1177    return;
1178  case TEK_Complex: {
1179    ComplexPairTy complex = EmitComplexExpr(init);
1180    if (capturedByInit)
1181      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
1182    EmitStoreOfComplex(complex, lvalue, /*init*/ true);
1183    return;
1184  }
1185  case TEK_Aggregate:
1186    if (type->isAtomicType()) {
1187      EmitAtomicInit(const_cast<Expr*>(init), lvalue);
1188    } else {
1189      // TODO: how can we delay here if D is captured by its initializer?
1190      EmitAggExpr(init, AggValueSlot::forLValue(lvalue,
1191                                              AggValueSlot::IsDestructed,
1192                                         AggValueSlot::DoesNotNeedGCBarriers,
1193                                              AggValueSlot::IsNotAliased));
1194    }
1195    return;
1196  }
1197  llvm_unreachable("bad evaluation kind");
1198}
1199
1200/// Enter a destroy cleanup for the given local variable.
1201void CodeGenFunction::emitAutoVarTypeCleanup(
1202                            const CodeGenFunction::AutoVarEmission &emission,
1203                            QualType::DestructionKind dtorKind) {
1204  assert(dtorKind != QualType::DK_none);
1205
1206  // Note that for __block variables, we want to destroy the
1207  // original stack object, not the possibly forwarded object.
1208  llvm::Value *addr = emission.getObjectAddress(*this);
1209
1210  const VarDecl *var = emission.Variable;
1211  QualType type = var->getType();
1212
1213  CleanupKind cleanupKind = NormalAndEHCleanup;
1214  CodeGenFunction::Destroyer *destroyer = nullptr;
1215
1216  switch (dtorKind) {
1217  case QualType::DK_none:
1218    llvm_unreachable("no cleanup for trivially-destructible variable");
1219
1220  case QualType::DK_cxx_destructor:
1221    // If there's an NRVO flag on the emission, we need a different
1222    // cleanup.
1223    if (emission.NRVOFlag) {
1224      assert(!type->isArrayType());
1225      CXXDestructorDecl *dtor = type->getAsCXXRecordDecl()->getDestructor();
1226      EHStack.pushCleanup<DestroyNRVOVariable>(cleanupKind, addr, dtor,
1227                                               emission.NRVOFlag);
1228      return;
1229    }
1230    break;
1231
1232  case QualType::DK_objc_strong_lifetime:
1233    // Suppress cleanups for pseudo-strong variables.
1234    if (var->isARCPseudoStrong()) return;
1235
1236    // Otherwise, consider whether to use an EH cleanup or not.
1237    cleanupKind = getARCCleanupKind();
1238
1239    // Use the imprecise destroyer by default.
1240    if (!var->hasAttr<ObjCPreciseLifetimeAttr>())
1241      destroyer = CodeGenFunction::destroyARCStrongImprecise;
1242    break;
1243
1244  case QualType::DK_objc_weak_lifetime:
1245    break;
1246  }
1247
1248  // If we haven't chosen a more specific destroyer, use the default.
1249  if (!destroyer) destroyer = getDestroyer(dtorKind);
1250
1251  // Use an EH cleanup in array destructors iff the destructor itself
1252  // is being pushed as an EH cleanup.
1253  bool useEHCleanup = (cleanupKind & EHCleanup);
1254  EHStack.pushCleanup<DestroyObject>(cleanupKind, addr, type, destroyer,
1255                                     useEHCleanup);
1256}
1257
1258void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) {
1259  assert(emission.Variable && "emission was not valid!");
1260
1261  // If this was emitted as a global constant, we're done.
1262  if (emission.wasEmittedAsGlobal()) return;
1263
1264  // If we don't have an insertion point, we're done.  Sema prevents
1265  // us from jumping into any of these scopes anyway.
1266  if (!HaveInsertPoint()) return;
1267
1268  const VarDecl &D = *emission.Variable;
1269
1270  // Make sure we call @llvm.lifetime.end.  This needs to happen
1271  // *last*, so the cleanup needs to be pushed *first*.
1272  if (emission.useLifetimeMarkers()) {
1273    EHStack.pushCleanup<CallLifetimeEnd>(NormalCleanup,
1274                                         emission.getAllocatedAddress(),
1275                                         emission.getSizeForLifetimeMarkers());
1276  }
1277
1278  // Check the type for a cleanup.
1279  if (QualType::DestructionKind dtorKind = D.getType().isDestructedType())
1280    emitAutoVarTypeCleanup(emission, dtorKind);
1281
1282  // In GC mode, honor objc_precise_lifetime.
1283  if (getLangOpts().getGC() != LangOptions::NonGC &&
1284      D.hasAttr<ObjCPreciseLifetimeAttr>()) {
1285    EHStack.pushCleanup<ExtendGCLifetime>(NormalCleanup, &D);
1286  }
1287
1288  // Handle the cleanup attribute.
1289  if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) {
1290    const FunctionDecl *FD = CA->getFunctionDecl();
1291
1292    llvm::Constant *F = CGM.GetAddrOfFunction(FD);
1293    assert(F && "Could not find function!");
1294
1295    const CGFunctionInfo &Info = CGM.getTypes().arrangeFunctionDeclaration(FD);
1296    EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup, F, &Info, &D);
1297  }
1298
1299  // If this is a block variable, call _Block_object_destroy
1300  // (on the unforwarded address).
1301  if (emission.IsByRef)
1302    enterByrefCleanup(emission);
1303}
1304
1305CodeGenFunction::Destroyer *
1306CodeGenFunction::getDestroyer(QualType::DestructionKind kind) {
1307  switch (kind) {
1308  case QualType::DK_none: llvm_unreachable("no destroyer for trivial dtor");
1309  case QualType::DK_cxx_destructor:
1310    return destroyCXXObject;
1311  case QualType::DK_objc_strong_lifetime:
1312    return destroyARCStrongPrecise;
1313  case QualType::DK_objc_weak_lifetime:
1314    return destroyARCWeak;
1315  }
1316  llvm_unreachable("Unknown DestructionKind");
1317}
1318
1319/// pushEHDestroy - Push the standard destructor for the given type as
1320/// an EH-only cleanup.
1321void CodeGenFunction::pushEHDestroy(QualType::DestructionKind dtorKind,
1322                                  llvm::Value *addr, QualType type) {
1323  assert(dtorKind && "cannot push destructor for trivial type");
1324  assert(needsEHCleanup(dtorKind));
1325
1326  pushDestroy(EHCleanup, addr, type, getDestroyer(dtorKind), true);
1327}
1328
1329/// pushDestroy - Push the standard destructor for the given type as
1330/// at least a normal cleanup.
1331void CodeGenFunction::pushDestroy(QualType::DestructionKind dtorKind,
1332                                  llvm::Value *addr, QualType type) {
1333  assert(dtorKind && "cannot push destructor for trivial type");
1334
1335  CleanupKind cleanupKind = getCleanupKind(dtorKind);
1336  pushDestroy(cleanupKind, addr, type, getDestroyer(dtorKind),
1337              cleanupKind & EHCleanup);
1338}
1339
1340void CodeGenFunction::pushDestroy(CleanupKind cleanupKind, llvm::Value *addr,
1341                                  QualType type, Destroyer *destroyer,
1342                                  bool useEHCleanupForArray) {
1343  pushFullExprCleanup<DestroyObject>(cleanupKind, addr, type,
1344                                     destroyer, useEHCleanupForArray);
1345}
1346
1347void CodeGenFunction::pushStackRestore(CleanupKind Kind, llvm::Value *SPMem) {
1348  EHStack.pushCleanup<CallStackRestore>(Kind, SPMem);
1349}
1350
1351void CodeGenFunction::pushLifetimeExtendedDestroy(
1352    CleanupKind cleanupKind, llvm::Value *addr, QualType type,
1353    Destroyer *destroyer, bool useEHCleanupForArray) {
1354  assert(!isInConditionalBranch() &&
1355         "performing lifetime extension from within conditional");
1356
1357  // Push an EH-only cleanup for the object now.
1358  // FIXME: When popping normal cleanups, we need to keep this EH cleanup
1359  // around in case a temporary's destructor throws an exception.
1360  if (cleanupKind & EHCleanup)
1361    EHStack.pushCleanup<DestroyObject>(
1362        static_cast<CleanupKind>(cleanupKind & ~NormalCleanup), addr, type,
1363        destroyer, useEHCleanupForArray);
1364
1365  // Remember that we need to push a full cleanup for the object at the
1366  // end of the full-expression.
1367  pushCleanupAfterFullExpr<DestroyObject>(
1368      cleanupKind, addr, type, destroyer, useEHCleanupForArray);
1369}
1370
1371/// emitDestroy - Immediately perform the destruction of the given
1372/// object.
1373///
1374/// \param addr - the address of the object; a type*
1375/// \param type - the type of the object; if an array type, all
1376///   objects are destroyed in reverse order
1377/// \param destroyer - the function to call to destroy individual
1378///   elements
1379/// \param useEHCleanupForArray - whether an EH cleanup should be
1380///   used when destroying array elements, in case one of the
1381///   destructions throws an exception
1382void CodeGenFunction::emitDestroy(llvm::Value *addr, QualType type,
1383                                  Destroyer *destroyer,
1384                                  bool useEHCleanupForArray) {
1385  const ArrayType *arrayType = getContext().getAsArrayType(type);
1386  if (!arrayType)
1387    return destroyer(*this, addr, type);
1388
1389  llvm::Value *begin = addr;
1390  llvm::Value *length = emitArrayLength(arrayType, type, begin);
1391
1392  // Normally we have to check whether the array is zero-length.
1393  bool checkZeroLength = true;
1394
1395  // But if the array length is constant, we can suppress that.
1396  if (llvm::ConstantInt *constLength = dyn_cast<llvm::ConstantInt>(length)) {
1397    // ...and if it's constant zero, we can just skip the entire thing.
1398    if (constLength->isZero()) return;
1399    checkZeroLength = false;
1400  }
1401
1402  llvm::Value *end = Builder.CreateInBoundsGEP(begin, length);
1403  emitArrayDestroy(begin, end, type, destroyer,
1404                   checkZeroLength, useEHCleanupForArray);
1405}
1406
1407/// emitArrayDestroy - Destroys all the elements of the given array,
1408/// beginning from last to first.  The array cannot be zero-length.
1409///
1410/// \param begin - a type* denoting the first element of the array
1411/// \param end - a type* denoting one past the end of the array
1412/// \param type - the element type of the array
1413/// \param destroyer - the function to call to destroy elements
1414/// \param useEHCleanup - whether to push an EH cleanup to destroy
1415///   the remaining elements in case the destruction of a single
1416///   element throws
1417void CodeGenFunction::emitArrayDestroy(llvm::Value *begin,
1418                                       llvm::Value *end,
1419                                       QualType type,
1420                                       Destroyer *destroyer,
1421                                       bool checkZeroLength,
1422                                       bool useEHCleanup) {
1423  assert(!type->isArrayType());
1424
1425  // The basic structure here is a do-while loop, because we don't
1426  // need to check for the zero-element case.
1427  llvm::BasicBlock *bodyBB = createBasicBlock("arraydestroy.body");
1428  llvm::BasicBlock *doneBB = createBasicBlock("arraydestroy.done");
1429
1430  if (checkZeroLength) {
1431    llvm::Value *isEmpty = Builder.CreateICmpEQ(begin, end,
1432                                                "arraydestroy.isempty");
1433    Builder.CreateCondBr(isEmpty, doneBB, bodyBB);
1434  }
1435
1436  // Enter the loop body, making that address the current address.
1437  llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
1438  EmitBlock(bodyBB);
1439  llvm::PHINode *elementPast =
1440    Builder.CreatePHI(begin->getType(), 2, "arraydestroy.elementPast");
1441  elementPast->addIncoming(end, entryBB);
1442
1443  // Shift the address back by one element.
1444  llvm::Value *negativeOne = llvm::ConstantInt::get(SizeTy, -1, true);
1445  llvm::Value *element = Builder.CreateInBoundsGEP(elementPast, negativeOne,
1446                                                   "arraydestroy.element");
1447
1448  if (useEHCleanup)
1449    pushRegularPartialArrayCleanup(begin, element, type, destroyer);
1450
1451  // Perform the actual destruction there.
1452  destroyer(*this, element, type);
1453
1454  if (useEHCleanup)
1455    PopCleanupBlock();
1456
1457  // Check whether we've reached the end.
1458  llvm::Value *done = Builder.CreateICmpEQ(element, begin, "arraydestroy.done");
1459  Builder.CreateCondBr(done, doneBB, bodyBB);
1460  elementPast->addIncoming(element, Builder.GetInsertBlock());
1461
1462  // Done.
1463  EmitBlock(doneBB);
1464}
1465
1466/// Perform partial array destruction as if in an EH cleanup.  Unlike
1467/// emitArrayDestroy, the element type here may still be an array type.
1468static void emitPartialArrayDestroy(CodeGenFunction &CGF,
1469                                    llvm::Value *begin, llvm::Value *end,
1470                                    QualType type,
1471                                    CodeGenFunction::Destroyer *destroyer) {
1472  // If the element type is itself an array, drill down.
1473  unsigned arrayDepth = 0;
1474  while (const ArrayType *arrayType = CGF.getContext().getAsArrayType(type)) {
1475    // VLAs don't require a GEP index to walk into.
1476    if (!isa<VariableArrayType>(arrayType))
1477      arrayDepth++;
1478    type = arrayType->getElementType();
1479  }
1480
1481  if (arrayDepth) {
1482    llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, arrayDepth+1);
1483
1484    SmallVector<llvm::Value*,4> gepIndices(arrayDepth, zero);
1485    begin = CGF.Builder.CreateInBoundsGEP(begin, gepIndices, "pad.arraybegin");
1486    end = CGF.Builder.CreateInBoundsGEP(end, gepIndices, "pad.arrayend");
1487  }
1488
1489  // Destroy the array.  We don't ever need an EH cleanup because we
1490  // assume that we're in an EH cleanup ourselves, so a throwing
1491  // destructor causes an immediate terminate.
1492  CGF.emitArrayDestroy(begin, end, type, destroyer,
1493                       /*checkZeroLength*/ true, /*useEHCleanup*/ false);
1494}
1495
1496namespace {
1497  /// RegularPartialArrayDestroy - a cleanup which performs a partial
1498  /// array destroy where the end pointer is regularly determined and
1499  /// does not need to be loaded from a local.
1500  class RegularPartialArrayDestroy : public EHScopeStack::Cleanup {
1501    llvm::Value *ArrayBegin;
1502    llvm::Value *ArrayEnd;
1503    QualType ElementType;
1504    CodeGenFunction::Destroyer *Destroyer;
1505  public:
1506    RegularPartialArrayDestroy(llvm::Value *arrayBegin, llvm::Value *arrayEnd,
1507                               QualType elementType,
1508                               CodeGenFunction::Destroyer *destroyer)
1509      : ArrayBegin(arrayBegin), ArrayEnd(arrayEnd),
1510        ElementType(elementType), Destroyer(destroyer) {}
1511
1512    void Emit(CodeGenFunction &CGF, Flags flags) override {
1513      emitPartialArrayDestroy(CGF, ArrayBegin, ArrayEnd,
1514                              ElementType, Destroyer);
1515    }
1516  };
1517
1518  /// IrregularPartialArrayDestroy - a cleanup which performs a
1519  /// partial array destroy where the end pointer is irregularly
1520  /// determined and must be loaded from a local.
1521  class IrregularPartialArrayDestroy : public EHScopeStack::Cleanup {
1522    llvm::Value *ArrayBegin;
1523    llvm::Value *ArrayEndPointer;
1524    QualType ElementType;
1525    CodeGenFunction::Destroyer *Destroyer;
1526  public:
1527    IrregularPartialArrayDestroy(llvm::Value *arrayBegin,
1528                                 llvm::Value *arrayEndPointer,
1529                                 QualType elementType,
1530                                 CodeGenFunction::Destroyer *destroyer)
1531      : ArrayBegin(arrayBegin), ArrayEndPointer(arrayEndPointer),
1532        ElementType(elementType), Destroyer(destroyer) {}
1533
1534    void Emit(CodeGenFunction &CGF, Flags flags) override {
1535      llvm::Value *arrayEnd = CGF.Builder.CreateLoad(ArrayEndPointer);
1536      emitPartialArrayDestroy(CGF, ArrayBegin, arrayEnd,
1537                              ElementType, Destroyer);
1538    }
1539  };
1540}
1541
1542/// pushIrregularPartialArrayCleanup - Push an EH cleanup to destroy
1543/// already-constructed elements of the given array.  The cleanup
1544/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
1545///
1546/// \param elementType - the immediate element type of the array;
1547///   possibly still an array type
1548void CodeGenFunction::pushIrregularPartialArrayCleanup(llvm::Value *arrayBegin,
1549                                                 llvm::Value *arrayEndPointer,
1550                                                       QualType elementType,
1551                                                       Destroyer *destroyer) {
1552  pushFullExprCleanup<IrregularPartialArrayDestroy>(EHCleanup,
1553                                                    arrayBegin, arrayEndPointer,
1554                                                    elementType, destroyer);
1555}
1556
1557/// pushRegularPartialArrayCleanup - Push an EH cleanup to destroy
1558/// already-constructed elements of the given array.  The cleanup
1559/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
1560///
1561/// \param elementType - the immediate element type of the array;
1562///   possibly still an array type
1563void CodeGenFunction::pushRegularPartialArrayCleanup(llvm::Value *arrayBegin,
1564                                                     llvm::Value *arrayEnd,
1565                                                     QualType elementType,
1566                                                     Destroyer *destroyer) {
1567  pushFullExprCleanup<RegularPartialArrayDestroy>(EHCleanup,
1568                                                  arrayBegin, arrayEnd,
1569                                                  elementType, destroyer);
1570}
1571
1572/// Lazily declare the @llvm.lifetime.start intrinsic.
1573llvm::Constant *CodeGenModule::getLLVMLifetimeStartFn() {
1574  if (LifetimeStartFn) return LifetimeStartFn;
1575  LifetimeStartFn = llvm::Intrinsic::getDeclaration(&getModule(),
1576                                            llvm::Intrinsic::lifetime_start);
1577  return LifetimeStartFn;
1578}
1579
1580/// Lazily declare the @llvm.lifetime.end intrinsic.
1581llvm::Constant *CodeGenModule::getLLVMLifetimeEndFn() {
1582  if (LifetimeEndFn) return LifetimeEndFn;
1583  LifetimeEndFn = llvm::Intrinsic::getDeclaration(&getModule(),
1584                                              llvm::Intrinsic::lifetime_end);
1585  return LifetimeEndFn;
1586}
1587
1588namespace {
1589  /// A cleanup to perform a release of an object at the end of a
1590  /// function.  This is used to balance out the incoming +1 of a
1591  /// ns_consumed argument when we can't reasonably do that just by
1592  /// not doing the initial retain for a __block argument.
1593  struct ConsumeARCParameter : EHScopeStack::Cleanup {
1594    ConsumeARCParameter(llvm::Value *param,
1595                        ARCPreciseLifetime_t precise)
1596      : Param(param), Precise(precise) {}
1597
1598    llvm::Value *Param;
1599    ARCPreciseLifetime_t Precise;
1600
1601    void Emit(CodeGenFunction &CGF, Flags flags) override {
1602      CGF.EmitARCRelease(Param, Precise);
1603    }
1604  };
1605}
1606
1607/// Emit an alloca (or GlobalValue depending on target)
1608/// for the specified parameter and set up LocalDeclMap.
1609void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg,
1610                                   bool ArgIsPointer, unsigned ArgNo) {
1611  // FIXME: Why isn't ImplicitParamDecl a ParmVarDecl?
1612  assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) &&
1613         "Invalid argument to EmitParmDecl");
1614
1615  Arg->setName(D.getName());
1616
1617  QualType Ty = D.getType();
1618
1619  // Use better IR generation for certain implicit parameters.
1620  if (isa<ImplicitParamDecl>(D)) {
1621    // The only implicit argument a block has is its literal.
1622    if (BlockInfo) {
1623      LocalDeclMap[&D] = Arg;
1624      llvm::Value *LocalAddr = nullptr;
1625      if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
1626        // Allocate a stack slot to let the debug info survive the RA.
1627        llvm::AllocaInst *Alloc = CreateTempAlloca(ConvertTypeForMem(Ty),
1628                                                   D.getName() + ".addr");
1629        Alloc->setAlignment(getContext().getDeclAlign(&D).getQuantity());
1630        LValue lv = MakeAddrLValue(Alloc, Ty, getContext().getDeclAlign(&D));
1631        EmitStoreOfScalar(Arg, lv, /* isInitialization */ true);
1632        LocalAddr = Builder.CreateLoad(Alloc);
1633      }
1634
1635      if (CGDebugInfo *DI = getDebugInfo()) {
1636        if (CGM.getCodeGenOpts().getDebugInfo()
1637              >= CodeGenOptions::LimitedDebugInfo) {
1638          DI->setLocation(D.getLocation());
1639          DI->EmitDeclareOfBlockLiteralArgVariable(*BlockInfo, Arg, LocalAddr, Builder);
1640        }
1641      }
1642
1643      return;
1644    }
1645  }
1646
1647  llvm::Value *DeclPtr;
1648  bool DoStore = false;
1649  bool IsScalar = hasScalarEvaluationKind(Ty);
1650  CharUnits Align = getContext().getDeclAlign(&D);
1651  // If we already have a pointer to the argument, reuse the input pointer.
1652  if (ArgIsPointer) {
1653    // If we have a prettier pointer type at this point, bitcast to that.
1654    unsigned AS = cast<llvm::PointerType>(Arg->getType())->getAddressSpace();
1655    llvm::Type *IRTy = ConvertTypeForMem(Ty)->getPointerTo(AS);
1656    DeclPtr = Arg->getType() == IRTy ? Arg : Builder.CreateBitCast(Arg, IRTy,
1657                                                                   D.getName());
1658    // Push a destructor cleanup for this parameter if the ABI requires it.
1659    if (!IsScalar &&
1660        getTarget().getCXXABI().areArgsDestroyedLeftToRightInCallee()) {
1661      const CXXRecordDecl *RD = Ty->getAsCXXRecordDecl();
1662      if (RD && RD->hasNonTrivialDestructor())
1663        pushDestroy(QualType::DK_cxx_destructor, DeclPtr, Ty);
1664    }
1665  } else {
1666    // Otherwise, create a temporary to hold the value.
1667    llvm::AllocaInst *Alloc = CreateTempAlloca(ConvertTypeForMem(Ty),
1668                                               D.getName() + ".addr");
1669    Alloc->setAlignment(Align.getQuantity());
1670    DeclPtr = Alloc;
1671    DoStore = true;
1672  }
1673
1674  LValue lv = MakeAddrLValue(DeclPtr, Ty, Align);
1675  if (IsScalar) {
1676    Qualifiers qs = Ty.getQualifiers();
1677    if (Qualifiers::ObjCLifetime lt = qs.getObjCLifetime()) {
1678      // We honor __attribute__((ns_consumed)) for types with lifetime.
1679      // For __strong, it's handled by just skipping the initial retain;
1680      // otherwise we have to balance out the initial +1 with an extra
1681      // cleanup to do the release at the end of the function.
1682      bool isConsumed = D.hasAttr<NSConsumedAttr>();
1683
1684      // 'self' is always formally __strong, but if this is not an
1685      // init method then we don't want to retain it.
1686      if (D.isARCPseudoStrong()) {
1687        const ObjCMethodDecl *method = cast<ObjCMethodDecl>(CurCodeDecl);
1688        assert(&D == method->getSelfDecl());
1689        assert(lt == Qualifiers::OCL_Strong);
1690        assert(qs.hasConst());
1691        assert(method->getMethodFamily() != OMF_init);
1692        (void) method;
1693        lt = Qualifiers::OCL_ExplicitNone;
1694      }
1695
1696      if (lt == Qualifiers::OCL_Strong) {
1697        if (!isConsumed) {
1698          if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
1699            // use objc_storeStrong(&dest, value) for retaining the
1700            // object. But first, store a null into 'dest' because
1701            // objc_storeStrong attempts to release its old value.
1702            llvm::Value *Null = CGM.EmitNullConstant(D.getType());
1703            EmitStoreOfScalar(Null, lv, /* isInitialization */ true);
1704            EmitARCStoreStrongCall(lv.getAddress(), Arg, true);
1705            DoStore = false;
1706          }
1707          else
1708          // Don't use objc_retainBlock for block pointers, because we
1709          // don't want to Block_copy something just because we got it
1710          // as a parameter.
1711            Arg = EmitARCRetainNonBlock(Arg);
1712        }
1713      } else {
1714        // Push the cleanup for a consumed parameter.
1715        if (isConsumed) {
1716          ARCPreciseLifetime_t precise = (D.hasAttr<ObjCPreciseLifetimeAttr>()
1717                                ? ARCPreciseLifetime : ARCImpreciseLifetime);
1718          EHStack.pushCleanup<ConsumeARCParameter>(getARCCleanupKind(), Arg,
1719                                                   precise);
1720        }
1721
1722        if (lt == Qualifiers::OCL_Weak) {
1723          EmitARCInitWeak(DeclPtr, Arg);
1724          DoStore = false; // The weak init is a store, no need to do two.
1725        }
1726      }
1727
1728      // Enter the cleanup scope.
1729      EmitAutoVarWithLifetime(*this, D, DeclPtr, lt);
1730    }
1731  }
1732
1733  // Store the initial value into the alloca.
1734  if (DoStore)
1735    EmitStoreOfScalar(Arg, lv, /* isInitialization */ true);
1736
1737  llvm::Value *&DMEntry = LocalDeclMap[&D];
1738  assert(!DMEntry && "Decl already exists in localdeclmap!");
1739  DMEntry = DeclPtr;
1740
1741  // Emit debug info for param declaration.
1742  if (CGDebugInfo *DI = getDebugInfo()) {
1743    if (CGM.getCodeGenOpts().getDebugInfo()
1744          >= CodeGenOptions::LimitedDebugInfo) {
1745      DI->EmitDeclareOfArgVariable(&D, DeclPtr, ArgNo, Builder);
1746    }
1747  }
1748
1749  if (D.hasAttr<AnnotateAttr>())
1750      EmitVarAnnotations(&D, DeclPtr);
1751}
1752