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::ExternCContext:
38  case Decl::Namespace:
39  case Decl::UnresolvedUsingTypename:
40  case Decl::ClassTemplateSpecialization:
41  case Decl::ClassTemplatePartialSpecialization:
42  case Decl::VarTemplateSpecialization:
43  case Decl::VarTemplatePartialSpecialization:
44  case Decl::TemplateTypeParm:
45  case Decl::UnresolvedUsingValue:
46  case Decl::NonTypeTemplateParm:
47  case Decl::CXXMethod:
48  case Decl::CXXConstructor:
49  case Decl::CXXDestructor:
50  case Decl::CXXConversion:
51  case Decl::Field:
52  case Decl::MSProperty:
53  case Decl::IndirectField:
54  case Decl::ObjCIvar:
55  case Decl::ObjCAtDefsField:
56  case Decl::ParmVar:
57  case Decl::ImplicitParam:
58  case Decl::ClassTemplate:
59  case Decl::VarTemplate:
60  case Decl::FunctionTemplate:
61  case Decl::TypeAliasTemplate:
62  case Decl::TemplateTemplateParm:
63  case Decl::ObjCMethod:
64  case Decl::ObjCCategory:
65  case Decl::ObjCProtocol:
66  case Decl::ObjCInterface:
67  case Decl::ObjCCategoryImpl:
68  case Decl::ObjCImplementation:
69  case Decl::ObjCProperty:
70  case Decl::ObjCCompatibleAlias:
71  case Decl::AccessSpec:
72  case Decl::LinkageSpec:
73  case Decl::ObjCPropertyImpl:
74  case Decl::FileScopeAsm:
75  case Decl::Friend:
76  case Decl::FriendTemplate:
77  case Decl::Block:
78  case Decl::Captured:
79  case Decl::ClassScopeFunctionSpecialization:
80  case Decl::UsingShadow:
81    llvm_unreachable("Declaration should not be in declstmts!");
82  case Decl::Function:  // void X();
83  case Decl::Record:    // struct/union/class X;
84  case Decl::Enum:      // enum X;
85  case Decl::EnumConstant: // enum ? { X = ? }
86  case Decl::CXXRecord: // struct/union/class X; [C++]
87  case Decl::StaticAssert: // static_assert(X, ""); [C++0x]
88  case Decl::Label:        // __label__ x;
89  case Decl::Import:
90  case Decl::OMPThreadPrivate:
91  case Decl::Empty:
92    // None of these decls require codegen support.
93    return;
94
95  case Decl::NamespaceAlias:
96    if (CGDebugInfo *DI = getDebugInfo())
97        DI->EmitNamespaceAlias(cast<NamespaceAliasDecl>(D));
98    return;
99  case Decl::Using:          // using X; [C++]
100    if (CGDebugInfo *DI = getDebugInfo())
101        DI->EmitUsingDecl(cast<UsingDecl>(D));
102    return;
103  case Decl::UsingDirective: // using namespace X; [C++]
104    if (CGDebugInfo *DI = getDebugInfo())
105      DI->EmitUsingDirective(cast<UsingDirectiveDecl>(D));
106    return;
107  case Decl::Var: {
108    const VarDecl &VD = cast<VarDecl>(D);
109    assert(VD.isLocalVarDecl() &&
110           "Should not see file-scope variables inside a function!");
111    return EmitVarDecl(VD);
112  }
113
114  case Decl::Typedef:      // typedef int X;
115  case Decl::TypeAlias: {  // using X = int; [C++0x]
116    const TypedefNameDecl &TD = cast<TypedefNameDecl>(D);
117    QualType Ty = TD.getUnderlyingType();
118
119    if (Ty->isVariablyModifiedType())
120      EmitVariablyModifiedType(Ty);
121  }
122  }
123}
124
125/// EmitVarDecl - This method handles emission of any variable declaration
126/// inside a function, including static vars etc.
127void CodeGenFunction::EmitVarDecl(const VarDecl &D) {
128  if (D.isStaticLocal()) {
129    llvm::GlobalValue::LinkageTypes Linkage =
130        CGM.getLLVMLinkageVarDefinition(&D, /*isConstant=*/false);
131
132    // FIXME: We need to force the emission/use of a guard variable for
133    // some variables even if we can constant-evaluate them because
134    // we can't guarantee every translation unit will constant-evaluate them.
135
136    return EmitStaticVarDecl(D, Linkage);
137  }
138
139  if (D.hasExternalStorage())
140    // Don't emit it now, allow it to be emitted lazily on its first use.
141    return;
142
143  if (D.getStorageClass() == SC_OpenCLWorkGroupLocal)
144    return CGM.getOpenCLRuntime().EmitWorkGroupLocalVarDecl(*this, D);
145
146  assert(D.hasLocalStorage());
147  return EmitAutoVarDecl(D);
148}
149
150static std::string getStaticDeclName(CodeGenModule &CGM, const VarDecl &D) {
151  if (CGM.getLangOpts().CPlusPlus)
152    return CGM.getMangledName(&D).str();
153
154  // If this isn't C++, we don't need a mangled name, just a pretty one.
155  assert(!D.isExternallyVisible() && "name shouldn't matter");
156  std::string ContextName;
157  const DeclContext *DC = D.getDeclContext();
158  if (const auto *FD = dyn_cast<FunctionDecl>(DC))
159    ContextName = CGM.getMangledName(FD);
160  else if (const auto *BD = dyn_cast<BlockDecl>(DC))
161    ContextName = CGM.getBlockMangledName(GlobalDecl(), BD);
162  else if (const auto *OMD = dyn_cast<ObjCMethodDecl>(DC))
163    ContextName = OMD->getSelector().getAsString();
164  else
165    llvm_unreachable("Unknown context for static var decl");
166
167  ContextName += "." + D.getNameAsString();
168  return ContextName;
169}
170
171llvm::Constant *CodeGenModule::getOrCreateStaticVarDecl(
172    const VarDecl &D, llvm::GlobalValue::LinkageTypes Linkage) {
173  // In general, we don't always emit static var decls once before we reference
174  // them. It is possible to reference them before emitting the function that
175  // contains them, and it is possible to emit the containing function multiple
176  // times.
177  if (llvm::Constant *ExistingGV = StaticLocalDeclMap[&D])
178    return ExistingGV;
179
180  QualType Ty = D.getType();
181  assert(Ty->isConstantSizeType() && "VLAs can't be static");
182
183  // Use the label if the variable is renamed with the asm-label extension.
184  std::string Name;
185  if (D.hasAttr<AsmLabelAttr>())
186    Name = getMangledName(&D);
187  else
188    Name = getStaticDeclName(*this, D);
189
190  llvm::Type *LTy = getTypes().ConvertTypeForMem(Ty);
191  unsigned AddrSpace =
192      GetGlobalVarAddressSpace(&D, getContext().getTargetAddressSpace(Ty));
193
194  // Local address space cannot have an initializer.
195  llvm::Constant *Init = nullptr;
196  if (Ty.getAddressSpace() != LangAS::opencl_local)
197    Init = EmitNullConstant(Ty);
198  else
199    Init = llvm::UndefValue::get(LTy);
200
201  llvm::GlobalVariable *GV =
202    new llvm::GlobalVariable(getModule(), LTy,
203                             Ty.isConstant(getContext()), Linkage,
204                             Init, Name, nullptr,
205                             llvm::GlobalVariable::NotThreadLocal,
206                             AddrSpace);
207  GV->setAlignment(getContext().getDeclAlign(&D).getQuantity());
208  setGlobalVisibility(GV, &D);
209
210  if (supportsCOMDAT() && GV->isWeakForLinker())
211    GV->setComdat(TheModule.getOrInsertComdat(GV->getName()));
212
213  if (D.getTLSKind())
214    setTLSMode(GV, D);
215
216  if (D.isExternallyVisible()) {
217    if (D.hasAttr<DLLImportAttr>())
218      GV->setDLLStorageClass(llvm::GlobalVariable::DLLImportStorageClass);
219    else if (D.hasAttr<DLLExportAttr>())
220      GV->setDLLStorageClass(llvm::GlobalVariable::DLLExportStorageClass);
221  }
222
223  // Make sure the result is of the correct type.
224  unsigned ExpectedAddrSpace = getContext().getTargetAddressSpace(Ty);
225  llvm::Constant *Addr = GV;
226  if (AddrSpace != ExpectedAddrSpace) {
227    llvm::PointerType *PTy = llvm::PointerType::get(LTy, ExpectedAddrSpace);
228    Addr = llvm::ConstantExpr::getAddrSpaceCast(GV, PTy);
229  }
230
231  setStaticLocalDeclAddress(&D, Addr);
232
233  // Ensure that the static local gets initialized by making sure the parent
234  // function gets emitted eventually.
235  const Decl *DC = cast<Decl>(D.getDeclContext());
236
237  // We can't name blocks or captured statements directly, so try to emit their
238  // parents.
239  if (isa<BlockDecl>(DC) || isa<CapturedDecl>(DC)) {
240    DC = DC->getNonClosureContext();
241    // FIXME: Ensure that global blocks get emitted.
242    if (!DC)
243      return Addr;
244  }
245
246  GlobalDecl GD;
247  if (const auto *CD = dyn_cast<CXXConstructorDecl>(DC))
248    GD = GlobalDecl(CD, Ctor_Base);
249  else if (const auto *DD = dyn_cast<CXXDestructorDecl>(DC))
250    GD = GlobalDecl(DD, Dtor_Base);
251  else if (const auto *FD = dyn_cast<FunctionDecl>(DC))
252    GD = GlobalDecl(FD);
253  else {
254    // Don't do anything for Obj-C method decls or global closures. We should
255    // never defer them.
256    assert(isa<ObjCMethodDecl>(DC) && "unexpected parent code decl");
257  }
258  if (GD.getDecl())
259    (void)GetAddrOfGlobal(GD);
260
261  return Addr;
262}
263
264/// hasNontrivialDestruction - Determine whether a type's destruction is
265/// non-trivial. If so, and the variable uses static initialization, we must
266/// register its destructor to run on exit.
267static bool hasNontrivialDestruction(QualType T) {
268  CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
269  return RD && !RD->hasTrivialDestructor();
270}
271
272/// AddInitializerToStaticVarDecl - Add the initializer for 'D' to the
273/// global variable that has already been created for it.  If the initializer
274/// has a different type than GV does, this may free GV and return a different
275/// one.  Otherwise it just returns GV.
276llvm::GlobalVariable *
277CodeGenFunction::AddInitializerToStaticVarDecl(const VarDecl &D,
278                                               llvm::GlobalVariable *GV) {
279  llvm::Constant *Init = CGM.EmitConstantInit(D, this);
280
281  // If constant emission failed, then this should be a C++ static
282  // initializer.
283  if (!Init) {
284    if (!getLangOpts().CPlusPlus)
285      CGM.ErrorUnsupported(D.getInit(), "constant l-value expression");
286    else if (Builder.GetInsertBlock()) {
287      // Since we have a static initializer, this global variable can't
288      // be constant.
289      GV->setConstant(false);
290
291      EmitCXXGuardedInit(D, GV, /*PerformInit*/true);
292    }
293    return GV;
294  }
295
296  // The initializer may differ in type from the global. Rewrite
297  // the global to match the initializer.  (We have to do this
298  // because some types, like unions, can't be completely represented
299  // in the LLVM type system.)
300  if (GV->getType()->getElementType() != Init->getType()) {
301    llvm::GlobalVariable *OldGV = GV;
302
303    GV = new llvm::GlobalVariable(CGM.getModule(), Init->getType(),
304                                  OldGV->isConstant(),
305                                  OldGV->getLinkage(), Init, "",
306                                  /*InsertBefore*/ OldGV,
307                                  OldGV->getThreadLocalMode(),
308                           CGM.getContext().getTargetAddressSpace(D.getType()));
309    GV->setVisibility(OldGV->getVisibility());
310
311    // Steal the name of the old global
312    GV->takeName(OldGV);
313
314    // Replace all uses of the old global with the new global
315    llvm::Constant *NewPtrForOldDecl =
316    llvm::ConstantExpr::getBitCast(GV, OldGV->getType());
317    OldGV->replaceAllUsesWith(NewPtrForOldDecl);
318
319    // Erase the old global, since it is no longer used.
320    OldGV->eraseFromParent();
321  }
322
323  GV->setConstant(CGM.isTypeConstant(D.getType(), true));
324  GV->setInitializer(Init);
325
326  if (hasNontrivialDestruction(D.getType())) {
327    // We have a constant initializer, but a nontrivial destructor. We still
328    // need to perform a guarded "initialization" in order to register the
329    // destructor.
330    EmitCXXGuardedInit(D, GV, /*PerformInit*/false);
331  }
332
333  return GV;
334}
335
336void CodeGenFunction::EmitStaticVarDecl(const VarDecl &D,
337                                      llvm::GlobalValue::LinkageTypes Linkage) {
338  llvm::Value *&DMEntry = LocalDeclMap[&D];
339  assert(!DMEntry && "Decl already exists in localdeclmap!");
340
341  // Check to see if we already have a global variable for this
342  // declaration.  This can happen when double-emitting function
343  // bodies, e.g. with complete and base constructors.
344  llvm::Constant *addr = CGM.getOrCreateStaticVarDecl(D, Linkage);
345
346  // Store into LocalDeclMap before generating initializer to handle
347  // circular references.
348  DMEntry = addr;
349
350  // We can't have a VLA here, but we can have a pointer to a VLA,
351  // even though that doesn't really make any sense.
352  // Make sure to evaluate VLA bounds now so that we have them for later.
353  if (D.getType()->isVariablyModifiedType())
354    EmitVariablyModifiedType(D.getType());
355
356  // Save the type in case adding the initializer forces a type change.
357  llvm::Type *expectedType = addr->getType();
358
359  llvm::GlobalVariable *var =
360    cast<llvm::GlobalVariable>(addr->stripPointerCasts());
361  // If this value has an initializer, emit it.
362  if (D.getInit())
363    var = AddInitializerToStaticVarDecl(D, var);
364
365  var->setAlignment(getContext().getDeclAlign(&D).getQuantity());
366
367  if (D.hasAttr<AnnotateAttr>())
368    CGM.AddGlobalAnnotations(&D, var);
369
370  if (const SectionAttr *SA = D.getAttr<SectionAttr>())
371    var->setSection(SA->getName());
372
373  if (D.hasAttr<UsedAttr>())
374    CGM.addUsedGlobal(var);
375
376  // We may have to cast the constant because of the initializer
377  // mismatch above.
378  //
379  // FIXME: It is really dangerous to store this in the map; if anyone
380  // RAUW's the GV uses of this constant will be invalid.
381  llvm::Constant *castedAddr =
382    llvm::ConstantExpr::getPointerBitCastOrAddrSpaceCast(var, expectedType);
383  DMEntry = castedAddr;
384  CGM.setStaticLocalDeclAddress(&D, castedAddr);
385
386  CGM.getSanitizerMetadata()->reportGlobalToASan(var, D);
387
388  // Emit global variable debug descriptor for static vars.
389  CGDebugInfo *DI = getDebugInfo();
390  if (DI &&
391      CGM.getCodeGenOpts().getDebugInfo() >= CodeGenOptions::LimitedDebugInfo) {
392    DI->setLocation(D.getLocation());
393    DI->EmitGlobalVariable(var, &D);
394  }
395}
396
397namespace {
398  struct DestroyObject : EHScopeStack::Cleanup {
399    DestroyObject(llvm::Value *addr, QualType type,
400                  CodeGenFunction::Destroyer *destroyer,
401                  bool useEHCleanupForArray)
402      : addr(addr), type(type), destroyer(destroyer),
403        useEHCleanupForArray(useEHCleanupForArray) {}
404
405    llvm::Value *addr;
406    QualType type;
407    CodeGenFunction::Destroyer *destroyer;
408    bool useEHCleanupForArray;
409
410    void Emit(CodeGenFunction &CGF, Flags flags) override {
411      // Don't use an EH cleanup recursively from an EH cleanup.
412      bool useEHCleanupForArray =
413        flags.isForNormalCleanup() && this->useEHCleanupForArray;
414
415      CGF.emitDestroy(addr, type, destroyer, useEHCleanupForArray);
416    }
417  };
418
419  struct DestroyNRVOVariable : EHScopeStack::Cleanup {
420    DestroyNRVOVariable(llvm::Value *addr,
421                        const CXXDestructorDecl *Dtor,
422                        llvm::Value *NRVOFlag)
423      : Dtor(Dtor), NRVOFlag(NRVOFlag), Loc(addr) {}
424
425    const CXXDestructorDecl *Dtor;
426    llvm::Value *NRVOFlag;
427    llvm::Value *Loc;
428
429    void Emit(CodeGenFunction &CGF, Flags flags) override {
430      // Along the exceptions path we always execute the dtor.
431      bool NRVO = flags.isForNormalCleanup() && NRVOFlag;
432
433      llvm::BasicBlock *SkipDtorBB = nullptr;
434      if (NRVO) {
435        // If we exited via NRVO, we skip the destructor call.
436        llvm::BasicBlock *RunDtorBB = CGF.createBasicBlock("nrvo.unused");
437        SkipDtorBB = CGF.createBasicBlock("nrvo.skipdtor");
438        llvm::Value *DidNRVO = CGF.Builder.CreateLoad(NRVOFlag, "nrvo.val");
439        CGF.Builder.CreateCondBr(DidNRVO, SkipDtorBB, RunDtorBB);
440        CGF.EmitBlock(RunDtorBB);
441      }
442
443      CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
444                                /*ForVirtualBase=*/false,
445                                /*Delegating=*/false,
446                                Loc);
447
448      if (NRVO) CGF.EmitBlock(SkipDtorBB);
449    }
450  };
451
452  struct CallStackRestore : EHScopeStack::Cleanup {
453    llvm::Value *Stack;
454    CallStackRestore(llvm::Value *Stack) : Stack(Stack) {}
455    void Emit(CodeGenFunction &CGF, Flags flags) override {
456      llvm::Value *V = CGF.Builder.CreateLoad(Stack);
457      llvm::Value *F = CGF.CGM.getIntrinsic(llvm::Intrinsic::stackrestore);
458      CGF.Builder.CreateCall(F, V);
459    }
460  };
461
462  struct ExtendGCLifetime : EHScopeStack::Cleanup {
463    const VarDecl &Var;
464    ExtendGCLifetime(const VarDecl *var) : Var(*var) {}
465
466    void Emit(CodeGenFunction &CGF, Flags flags) override {
467      // Compute the address of the local variable, in case it's a
468      // byref or something.
469      DeclRefExpr DRE(const_cast<VarDecl*>(&Var), false,
470                      Var.getType(), VK_LValue, SourceLocation());
471      llvm::Value *value = CGF.EmitLoadOfScalar(CGF.EmitDeclRefLValue(&DRE),
472                                                SourceLocation());
473      CGF.EmitExtendGCLifetime(value);
474    }
475  };
476
477  struct CallCleanupFunction : EHScopeStack::Cleanup {
478    llvm::Constant *CleanupFn;
479    const CGFunctionInfo &FnInfo;
480    const VarDecl &Var;
481
482    CallCleanupFunction(llvm::Constant *CleanupFn, const CGFunctionInfo *Info,
483                        const VarDecl *Var)
484      : CleanupFn(CleanupFn), FnInfo(*Info), Var(*Var) {}
485
486    void Emit(CodeGenFunction &CGF, Flags flags) override {
487      DeclRefExpr DRE(const_cast<VarDecl*>(&Var), false,
488                      Var.getType(), VK_LValue, SourceLocation());
489      // Compute the address of the local variable, in case it's a byref
490      // or something.
491      llvm::Value *Addr = CGF.EmitDeclRefLValue(&DRE).getAddress();
492
493      // In some cases, the type of the function argument will be different from
494      // the type of the pointer. An example of this is
495      // void f(void* arg);
496      // __attribute__((cleanup(f))) void *g;
497      //
498      // To fix this we insert a bitcast here.
499      QualType ArgTy = FnInfo.arg_begin()->type;
500      llvm::Value *Arg =
501        CGF.Builder.CreateBitCast(Addr, CGF.ConvertType(ArgTy));
502
503      CallArgList Args;
504      Args.add(RValue::get(Arg),
505               CGF.getContext().getPointerType(Var.getType()));
506      CGF.EmitCall(FnInfo, CleanupFn, ReturnValueSlot(), Args);
507    }
508  };
509
510  /// A cleanup to call @llvm.lifetime.end.
511  class CallLifetimeEnd : public EHScopeStack::Cleanup {
512    llvm::Value *Addr;
513    llvm::Value *Size;
514  public:
515    CallLifetimeEnd(llvm::Value *addr, llvm::Value *size)
516      : Addr(addr), Size(size) {}
517
518    void Emit(CodeGenFunction &CGF, Flags flags) override {
519      llvm::Value *castAddr = CGF.Builder.CreateBitCast(Addr, CGF.Int8PtrTy);
520      CGF.Builder.CreateCall2(CGF.CGM.getLLVMLifetimeEndFn(),
521                              Size, castAddr)
522        ->setDoesNotThrow();
523    }
524  };
525}
526
527/// EmitAutoVarWithLifetime - Does the setup required for an automatic
528/// variable with lifetime.
529static void EmitAutoVarWithLifetime(CodeGenFunction &CGF, const VarDecl &var,
530                                    llvm::Value *addr,
531                                    Qualifiers::ObjCLifetime lifetime) {
532  switch (lifetime) {
533  case Qualifiers::OCL_None:
534    llvm_unreachable("present but none");
535
536  case Qualifiers::OCL_ExplicitNone:
537    // nothing to do
538    break;
539
540  case Qualifiers::OCL_Strong: {
541    CodeGenFunction::Destroyer *destroyer =
542      (var.hasAttr<ObjCPreciseLifetimeAttr>()
543       ? CodeGenFunction::destroyARCStrongPrecise
544       : CodeGenFunction::destroyARCStrongImprecise);
545
546    CleanupKind cleanupKind = CGF.getARCCleanupKind();
547    CGF.pushDestroy(cleanupKind, addr, var.getType(), destroyer,
548                    cleanupKind & EHCleanup);
549    break;
550  }
551  case Qualifiers::OCL_Autoreleasing:
552    // nothing to do
553    break;
554
555  case Qualifiers::OCL_Weak:
556    // __weak objects always get EH cleanups; otherwise, exceptions
557    // could cause really nasty crashes instead of mere leaks.
558    CGF.pushDestroy(NormalAndEHCleanup, addr, var.getType(),
559                    CodeGenFunction::destroyARCWeak,
560                    /*useEHCleanup*/ true);
561    break;
562  }
563}
564
565static bool isAccessedBy(const VarDecl &var, const Stmt *s) {
566  if (const Expr *e = dyn_cast<Expr>(s)) {
567    // Skip the most common kinds of expressions that make
568    // hierarchy-walking expensive.
569    s = e = e->IgnoreParenCasts();
570
571    if (const DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e))
572      return (ref->getDecl() == &var);
573    if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) {
574      const BlockDecl *block = be->getBlockDecl();
575      for (const auto &I : block->captures()) {
576        if (I.getVariable() == &var)
577          return true;
578      }
579    }
580  }
581
582  for (Stmt::const_child_range children = s->children(); children; ++children)
583    // children might be null; as in missing decl or conditional of an if-stmt.
584    if ((*children) && isAccessedBy(var, *children))
585      return true;
586
587  return false;
588}
589
590static bool isAccessedBy(const ValueDecl *decl, const Expr *e) {
591  if (!decl) return false;
592  if (!isa<VarDecl>(decl)) return false;
593  const VarDecl *var = cast<VarDecl>(decl);
594  return isAccessedBy(*var, e);
595}
596
597static void drillIntoBlockVariable(CodeGenFunction &CGF,
598                                   LValue &lvalue,
599                                   const VarDecl *var) {
600  lvalue.setAddress(CGF.BuildBlockByrefAddress(lvalue.getAddress(), var));
601}
602
603void CodeGenFunction::EmitScalarInit(const Expr *init, const ValueDecl *D,
604                                     LValue lvalue, bool capturedByInit) {
605  Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
606  if (!lifetime) {
607    llvm::Value *value = EmitScalarExpr(init);
608    if (capturedByInit)
609      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
610    EmitStoreThroughLValue(RValue::get(value), lvalue, true);
611    return;
612  }
613
614  if (const CXXDefaultInitExpr *DIE = dyn_cast<CXXDefaultInitExpr>(init))
615    init = DIE->getExpr();
616
617  // If we're emitting a value with lifetime, we have to do the
618  // initialization *before* we leave the cleanup scopes.
619  if (const ExprWithCleanups *ewc = dyn_cast<ExprWithCleanups>(init)) {
620    enterFullExpression(ewc);
621    init = ewc->getSubExpr();
622  }
623  CodeGenFunction::RunCleanupsScope Scope(*this);
624
625  // We have to maintain the illusion that the variable is
626  // zero-initialized.  If the variable might be accessed in its
627  // initializer, zero-initialize before running the initializer, then
628  // actually perform the initialization with an assign.
629  bool accessedByInit = false;
630  if (lifetime != Qualifiers::OCL_ExplicitNone)
631    accessedByInit = (capturedByInit || isAccessedBy(D, init));
632  if (accessedByInit) {
633    LValue tempLV = lvalue;
634    // Drill down to the __block object if necessary.
635    if (capturedByInit) {
636      // We can use a simple GEP for this because it can't have been
637      // moved yet.
638      tempLV.setAddress(Builder.CreateStructGEP(
639          nullptr, tempLV.getAddress(),
640          getByRefValueLLVMField(cast<VarDecl>(D)).second));
641    }
642
643    llvm::PointerType *ty
644      = cast<llvm::PointerType>(tempLV.getAddress()->getType());
645    ty = cast<llvm::PointerType>(ty->getElementType());
646
647    llvm::Value *zero = llvm::ConstantPointerNull::get(ty);
648
649    // If __weak, we want to use a barrier under certain conditions.
650    if (lifetime == Qualifiers::OCL_Weak)
651      EmitARCInitWeak(tempLV.getAddress(), zero);
652
653    // Otherwise just do a simple store.
654    else
655      EmitStoreOfScalar(zero, tempLV, /* isInitialization */ true);
656  }
657
658  // Emit the initializer.
659  llvm::Value *value = nullptr;
660
661  switch (lifetime) {
662  case Qualifiers::OCL_None:
663    llvm_unreachable("present but none");
664
665  case Qualifiers::OCL_ExplicitNone:
666    // nothing to do
667    value = EmitScalarExpr(init);
668    break;
669
670  case Qualifiers::OCL_Strong: {
671    value = EmitARCRetainScalarExpr(init);
672    break;
673  }
674
675  case Qualifiers::OCL_Weak: {
676    // No way to optimize a producing initializer into this.  It's not
677    // worth optimizing for, because the value will immediately
678    // disappear in the common case.
679    value = EmitScalarExpr(init);
680
681    if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
682    if (accessedByInit)
683      EmitARCStoreWeak(lvalue.getAddress(), value, /*ignored*/ true);
684    else
685      EmitARCInitWeak(lvalue.getAddress(), value);
686    return;
687  }
688
689  case Qualifiers::OCL_Autoreleasing:
690    value = EmitARCRetainAutoreleaseScalarExpr(init);
691    break;
692  }
693
694  if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
695
696  // If the variable might have been accessed by its initializer, we
697  // might have to initialize with a barrier.  We have to do this for
698  // both __weak and __strong, but __weak got filtered out above.
699  if (accessedByInit && lifetime == Qualifiers::OCL_Strong) {
700    llvm::Value *oldValue = EmitLoadOfScalar(lvalue, init->getExprLoc());
701    EmitStoreOfScalar(value, lvalue, /* isInitialization */ true);
702    EmitARCRelease(oldValue, ARCImpreciseLifetime);
703    return;
704  }
705
706  EmitStoreOfScalar(value, lvalue, /* isInitialization */ true);
707}
708
709/// EmitScalarInit - Initialize the given lvalue with the given object.
710void CodeGenFunction::EmitScalarInit(llvm::Value *init, LValue lvalue) {
711  Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
712  if (!lifetime)
713    return EmitStoreThroughLValue(RValue::get(init), lvalue, true);
714
715  switch (lifetime) {
716  case Qualifiers::OCL_None:
717    llvm_unreachable("present but none");
718
719  case Qualifiers::OCL_ExplicitNone:
720    // nothing to do
721    break;
722
723  case Qualifiers::OCL_Strong:
724    init = EmitARCRetain(lvalue.getType(), init);
725    break;
726
727  case Qualifiers::OCL_Weak:
728    // Initialize and then skip the primitive store.
729    EmitARCInitWeak(lvalue.getAddress(), init);
730    return;
731
732  case Qualifiers::OCL_Autoreleasing:
733    init = EmitARCRetainAutorelease(lvalue.getType(), init);
734    break;
735  }
736
737  EmitStoreOfScalar(init, lvalue, /* isInitialization */ true);
738}
739
740/// canEmitInitWithFewStoresAfterMemset - Decide whether we can emit the
741/// non-zero parts of the specified initializer with equal or fewer than
742/// NumStores scalar stores.
743static bool canEmitInitWithFewStoresAfterMemset(llvm::Constant *Init,
744                                                unsigned &NumStores) {
745  // Zero and Undef never requires any extra stores.
746  if (isa<llvm::ConstantAggregateZero>(Init) ||
747      isa<llvm::ConstantPointerNull>(Init) ||
748      isa<llvm::UndefValue>(Init))
749    return true;
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    return Init->isNullValue() || NumStores--;
754
755  // See if we can emit each element.
756  if (isa<llvm::ConstantArray>(Init) || isa<llvm::ConstantStruct>(Init)) {
757    for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
758      llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
759      if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores))
760        return false;
761    }
762    return true;
763  }
764
765  if (llvm::ConstantDataSequential *CDS =
766        dyn_cast<llvm::ConstantDataSequential>(Init)) {
767    for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
768      llvm::Constant *Elt = CDS->getElementAsConstant(i);
769      if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores))
770        return false;
771    }
772    return true;
773  }
774
775  // Anything else is hard and scary.
776  return false;
777}
778
779/// emitStoresForInitAfterMemset - For inits that
780/// canEmitInitWithFewStoresAfterMemset returned true for, emit the scalar
781/// stores that would be required.
782static void emitStoresForInitAfterMemset(llvm::Constant *Init, llvm::Value *Loc,
783                                         bool isVolatile, CGBuilderTy &Builder) {
784  assert(!Init->isNullValue() && !isa<llvm::UndefValue>(Init) &&
785         "called emitStoresForInitAfterMemset for zero or undef value.");
786
787  if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
788      isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
789      isa<llvm::ConstantExpr>(Init)) {
790    Builder.CreateStore(Init, Loc, isVolatile);
791    return;
792  }
793
794  if (llvm::ConstantDataSequential *CDS =
795        dyn_cast<llvm::ConstantDataSequential>(Init)) {
796    for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
797      llvm::Constant *Elt = CDS->getElementAsConstant(i);
798
799      // If necessary, get a pointer to the element and emit it.
800      if (!Elt->isNullValue() && !isa<llvm::UndefValue>(Elt))
801        emitStoresForInitAfterMemset(
802            Elt, Builder.CreateConstGEP2_32(Init->getType(), Loc, 0, i),
803            isVolatile, Builder);
804    }
805    return;
806  }
807
808  assert((isa<llvm::ConstantStruct>(Init) || isa<llvm::ConstantArray>(Init)) &&
809         "Unknown value type!");
810
811  for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
812    llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
813
814    // If necessary, get a pointer to the element and emit it.
815    if (!Elt->isNullValue() && !isa<llvm::UndefValue>(Elt))
816      emitStoresForInitAfterMemset(
817          Elt, Builder.CreateConstGEP2_32(Init->getType(), Loc, 0, i),
818          isVolatile, Builder);
819  }
820}
821
822
823/// shouldUseMemSetPlusStoresToInitialize - Decide whether we should use memset
824/// plus some stores to initialize a local variable instead of using a memcpy
825/// from a constant global.  It is beneficial to use memset if the global is all
826/// zeros, or mostly zeros and large.
827static bool shouldUseMemSetPlusStoresToInitialize(llvm::Constant *Init,
828                                                  uint64_t GlobalSize) {
829  // If a global is all zeros, always use a memset.
830  if (isa<llvm::ConstantAggregateZero>(Init)) return true;
831
832  // If a non-zero global is <= 32 bytes, always use a memcpy.  If it is large,
833  // do it if it will require 6 or fewer scalar stores.
834  // TODO: Should budget depends on the size?  Avoiding a large global warrants
835  // plopping in more stores.
836  unsigned StoreBudget = 6;
837  uint64_t SizeLimit = 32;
838
839  return GlobalSize > SizeLimit &&
840         canEmitInitWithFewStoresAfterMemset(Init, StoreBudget);
841}
842
843/// Should we use the LLVM lifetime intrinsics for the given local variable?
844static bool shouldUseLifetimeMarkers(CodeGenFunction &CGF, const VarDecl &D,
845                                     unsigned Size) {
846  // For now, only in optimized builds.
847  if (CGF.CGM.getCodeGenOpts().OptimizationLevel == 0)
848    return false;
849
850  // Limit the size of marked objects to 32 bytes. We don't want to increase
851  // compile time by marking tiny objects.
852  unsigned SizeThreshold = 32;
853
854  return Size > SizeThreshold;
855}
856
857
858/// EmitAutoVarDecl - Emit code and set up an entry in LocalDeclMap for a
859/// variable declaration with auto, register, or no storage class specifier.
860/// These turn into simple stack objects, or GlobalValues depending on target.
861void CodeGenFunction::EmitAutoVarDecl(const VarDecl &D) {
862  AutoVarEmission emission = EmitAutoVarAlloca(D);
863  EmitAutoVarInit(emission);
864  EmitAutoVarCleanups(emission);
865}
866
867/// EmitAutoVarAlloca - Emit the alloca and debug information for a
868/// local variable.  Does not emit initialization or destruction.
869CodeGenFunction::AutoVarEmission
870CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) {
871  QualType Ty = D.getType();
872
873  AutoVarEmission emission(D);
874
875  bool isByRef = D.hasAttr<BlocksAttr>();
876  emission.IsByRef = isByRef;
877
878  CharUnits alignment = getContext().getDeclAlign(&D);
879  emission.Alignment = alignment;
880
881  // If the type is variably-modified, emit all the VLA sizes for it.
882  if (Ty->isVariablyModifiedType())
883    EmitVariablyModifiedType(Ty);
884
885  llvm::Value *DeclPtr;
886  if (Ty->isConstantSizeType()) {
887    bool NRVO = getLangOpts().ElideConstructors &&
888      D.isNRVOVariable();
889
890    // If this value is an array or struct with a statically determinable
891    // constant initializer, there are optimizations we can do.
892    //
893    // TODO: We should constant-evaluate the initializer of any variable,
894    // as long as it is initialized by a constant expression. Currently,
895    // isConstantInitializer produces wrong answers for structs with
896    // reference or bitfield members, and a few other cases, and checking
897    // for POD-ness protects us from some of these.
898    if (D.getInit() && (Ty->isArrayType() || Ty->isRecordType()) &&
899        (D.isConstexpr() ||
900         ((Ty.isPODType(getContext()) ||
901           getContext().getBaseElementType(Ty)->isObjCObjectPointerType()) &&
902          D.getInit()->isConstantInitializer(getContext(), false)))) {
903
904      // If the variable's a const type, and it's neither an NRVO
905      // candidate nor a __block variable and has no mutable members,
906      // emit it as a global instead.
907      if (CGM.getCodeGenOpts().MergeAllConstants && !NRVO && !isByRef &&
908          CGM.isTypeConstant(Ty, true)) {
909        EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage);
910
911        emission.Address = nullptr; // signal this condition to later callbacks
912        assert(emission.wasEmittedAsGlobal());
913        return emission;
914      }
915
916      // Otherwise, tell the initialization code that we're in this case.
917      emission.IsConstantAggregate = true;
918    }
919
920    // A normal fixed sized variable becomes an alloca in the entry block,
921    // unless it's an NRVO variable.
922    llvm::Type *LTy = ConvertTypeForMem(Ty);
923
924    if (NRVO) {
925      // The named return value optimization: allocate this variable in the
926      // return slot, so that we can elide the copy when returning this
927      // variable (C++0x [class.copy]p34).
928      DeclPtr = ReturnValue;
929
930      if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
931        if (!cast<CXXRecordDecl>(RecordTy->getDecl())->hasTrivialDestructor()) {
932          // Create a flag that is used to indicate when the NRVO was applied
933          // to this variable. Set it to zero to indicate that NRVO was not
934          // applied.
935          llvm::Value *Zero = Builder.getFalse();
936          llvm::Value *NRVOFlag = CreateTempAlloca(Zero->getType(), "nrvo");
937          EnsureInsertPoint();
938          Builder.CreateStore(Zero, NRVOFlag);
939
940          // Record the NRVO flag for this variable.
941          NRVOFlags[&D] = NRVOFlag;
942          emission.NRVOFlag = NRVOFlag;
943        }
944      }
945    } else {
946      if (isByRef)
947        LTy = BuildByRefType(&D);
948
949      llvm::AllocaInst *Alloc = CreateTempAlloca(LTy);
950      Alloc->setName(D.getName());
951
952      CharUnits allocaAlignment = alignment;
953      if (isByRef)
954        allocaAlignment = std::max(allocaAlignment,
955            getContext().toCharUnitsFromBits(getTarget().getPointerAlign(0)));
956      Alloc->setAlignment(allocaAlignment.getQuantity());
957      DeclPtr = Alloc;
958
959      // Emit a lifetime intrinsic if meaningful.  There's no point
960      // in doing this if we don't have a valid insertion point (?).
961      uint64_t size = CGM.getDataLayout().getTypeAllocSize(LTy);
962      if (HaveInsertPoint() && shouldUseLifetimeMarkers(*this, D, size)) {
963        llvm::Value *sizeV = llvm::ConstantInt::get(Int64Ty, size);
964
965        emission.SizeForLifetimeMarkers = sizeV;
966        llvm::Value *castAddr = Builder.CreateBitCast(Alloc, Int8PtrTy);
967        Builder.CreateCall2(CGM.getLLVMLifetimeStartFn(), sizeV, castAddr)
968          ->setDoesNotThrow();
969      } else {
970        assert(!emission.useLifetimeMarkers());
971      }
972    }
973  } else {
974    EnsureInsertPoint();
975
976    if (!DidCallStackSave) {
977      // Save the stack.
978      llvm::Value *Stack = CreateTempAlloca(Int8PtrTy, "saved_stack");
979
980      llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave);
981      llvm::Value *V = Builder.CreateCall(F);
982
983      Builder.CreateStore(V, Stack);
984
985      DidCallStackSave = true;
986
987      // Push a cleanup block and restore the stack there.
988      // FIXME: in general circumstances, this should be an EH cleanup.
989      pushStackRestore(NormalCleanup, Stack);
990    }
991
992    llvm::Value *elementCount;
993    QualType elementType;
994    std::tie(elementCount, elementType) = getVLASize(Ty);
995
996    llvm::Type *llvmTy = ConvertTypeForMem(elementType);
997
998    // Allocate memory for the array.
999    llvm::AllocaInst *vla = Builder.CreateAlloca(llvmTy, elementCount, "vla");
1000    vla->setAlignment(alignment.getQuantity());
1001
1002    DeclPtr = vla;
1003  }
1004
1005  llvm::Value *&DMEntry = LocalDeclMap[&D];
1006  assert(!DMEntry && "Decl already exists in localdeclmap!");
1007  DMEntry = DeclPtr;
1008  emission.Address = DeclPtr;
1009
1010  // Emit debug info for local var declaration.
1011  if (HaveInsertPoint())
1012    if (CGDebugInfo *DI = getDebugInfo()) {
1013      if (CGM.getCodeGenOpts().getDebugInfo()
1014            >= CodeGenOptions::LimitedDebugInfo) {
1015        DI->setLocation(D.getLocation());
1016        DI->EmitDeclareOfAutoVariable(&D, DeclPtr, Builder);
1017      }
1018    }
1019
1020  if (D.hasAttr<AnnotateAttr>())
1021      EmitVarAnnotations(&D, emission.Address);
1022
1023  return emission;
1024}
1025
1026/// Determines whether the given __block variable is potentially
1027/// captured by the given expression.
1028static bool isCapturedBy(const VarDecl &var, const Expr *e) {
1029  // Skip the most common kinds of expressions that make
1030  // hierarchy-walking expensive.
1031  e = e->IgnoreParenCasts();
1032
1033  if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) {
1034    const BlockDecl *block = be->getBlockDecl();
1035    for (const auto &I : block->captures()) {
1036      if (I.getVariable() == &var)
1037        return true;
1038    }
1039
1040    // No need to walk into the subexpressions.
1041    return false;
1042  }
1043
1044  if (const StmtExpr *SE = dyn_cast<StmtExpr>(e)) {
1045    const CompoundStmt *CS = SE->getSubStmt();
1046    for (const auto *BI : CS->body())
1047      if (const auto *E = dyn_cast<Expr>(BI)) {
1048        if (isCapturedBy(var, E))
1049            return true;
1050      }
1051      else if (const auto *DS = dyn_cast<DeclStmt>(BI)) {
1052          // special case declarations
1053          for (const auto *I : DS->decls()) {
1054              if (const auto *VD = dyn_cast<VarDecl>((I))) {
1055                const Expr *Init = VD->getInit();
1056                if (Init && isCapturedBy(var, Init))
1057                  return true;
1058              }
1059          }
1060      }
1061      else
1062        // FIXME. Make safe assumption assuming arbitrary statements cause capturing.
1063        // Later, provide code to poke into statements for capture analysis.
1064        return true;
1065    return false;
1066  }
1067
1068  for (Stmt::const_child_range children = e->children(); children; ++children)
1069    if (isCapturedBy(var, cast<Expr>(*children)))
1070      return true;
1071
1072  return false;
1073}
1074
1075/// \brief Determine whether the given initializer is trivial in the sense
1076/// that it requires no code to be generated.
1077bool CodeGenFunction::isTrivialInitializer(const Expr *Init) {
1078  if (!Init)
1079    return true;
1080
1081  if (const CXXConstructExpr *Construct = dyn_cast<CXXConstructExpr>(Init))
1082    if (CXXConstructorDecl *Constructor = Construct->getConstructor())
1083      if (Constructor->isTrivial() &&
1084          Constructor->isDefaultConstructor() &&
1085          !Construct->requiresZeroInitialization())
1086        return true;
1087
1088  return false;
1089}
1090void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) {
1091  assert(emission.Variable && "emission was not valid!");
1092
1093  // If this was emitted as a global constant, we're done.
1094  if (emission.wasEmittedAsGlobal()) return;
1095
1096  const VarDecl &D = *emission.Variable;
1097  auto DL = ApplyDebugLocation::CreateDefaultArtificial(*this, D.getLocation());
1098  QualType type = D.getType();
1099
1100  // If this local has an initializer, emit it now.
1101  const Expr *Init = D.getInit();
1102
1103  // If we are at an unreachable point, we don't need to emit the initializer
1104  // unless it contains a label.
1105  if (!HaveInsertPoint()) {
1106    if (!Init || !ContainsLabel(Init)) return;
1107    EnsureInsertPoint();
1108  }
1109
1110  // Initialize the structure of a __block variable.
1111  if (emission.IsByRef)
1112    emitByrefStructureInit(emission);
1113
1114  if (isTrivialInitializer(Init))
1115    return;
1116
1117  CharUnits alignment = emission.Alignment;
1118
1119  // Check whether this is a byref variable that's potentially
1120  // captured and moved by its own initializer.  If so, we'll need to
1121  // emit the initializer first, then copy into the variable.
1122  bool capturedByInit = emission.IsByRef && isCapturedBy(D, Init);
1123
1124  llvm::Value *Loc =
1125    capturedByInit ? emission.Address : emission.getObjectAddress(*this);
1126
1127  llvm::Constant *constant = nullptr;
1128  if (emission.IsConstantAggregate || D.isConstexpr()) {
1129    assert(!capturedByInit && "constant init contains a capturing block?");
1130    constant = CGM.EmitConstantInit(D, this);
1131  }
1132
1133  if (!constant) {
1134    LValue lv = MakeAddrLValue(Loc, type, alignment);
1135    lv.setNonGC(true);
1136    return EmitExprAsInit(Init, &D, lv, capturedByInit);
1137  }
1138
1139  if (!emission.IsConstantAggregate) {
1140    // For simple scalar/complex initialization, store the value directly.
1141    LValue lv = MakeAddrLValue(Loc, type, alignment);
1142    lv.setNonGC(true);
1143    return EmitStoreThroughLValue(RValue::get(constant), lv, true);
1144  }
1145
1146  // If this is a simple aggregate initialization, we can optimize it
1147  // in various ways.
1148  bool isVolatile = type.isVolatileQualified();
1149
1150  llvm::Value *SizeVal =
1151    llvm::ConstantInt::get(IntPtrTy,
1152                           getContext().getTypeSizeInChars(type).getQuantity());
1153
1154  llvm::Type *BP = Int8PtrTy;
1155  if (Loc->getType() != BP)
1156    Loc = Builder.CreateBitCast(Loc, BP);
1157
1158  // If the initializer is all or mostly zeros, codegen with memset then do
1159  // a few stores afterward.
1160  if (shouldUseMemSetPlusStoresToInitialize(constant,
1161                CGM.getDataLayout().getTypeAllocSize(constant->getType()))) {
1162    Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, 0), SizeVal,
1163                         alignment.getQuantity(), isVolatile);
1164    // Zero and undef don't require a stores.
1165    if (!constant->isNullValue() && !isa<llvm::UndefValue>(constant)) {
1166      Loc = Builder.CreateBitCast(Loc, constant->getType()->getPointerTo());
1167      emitStoresForInitAfterMemset(constant, Loc, isVolatile, Builder);
1168    }
1169  } else {
1170    // Otherwise, create a temporary global with the initializer then
1171    // memcpy from the global to the alloca.
1172    std::string Name = getStaticDeclName(CGM, D);
1173    llvm::GlobalVariable *GV =
1174      new llvm::GlobalVariable(CGM.getModule(), constant->getType(), true,
1175                               llvm::GlobalValue::PrivateLinkage,
1176                               constant, Name);
1177    GV->setAlignment(alignment.getQuantity());
1178    GV->setUnnamedAddr(true);
1179
1180    llvm::Value *SrcPtr = GV;
1181    if (SrcPtr->getType() != BP)
1182      SrcPtr = Builder.CreateBitCast(SrcPtr, BP);
1183
1184    Builder.CreateMemCpy(Loc, SrcPtr, SizeVal, alignment.getQuantity(),
1185                         isVolatile);
1186  }
1187}
1188
1189/// Emit an expression as an initializer for a variable at the given
1190/// location.  The expression is not necessarily the normal
1191/// initializer for the variable, and the address is not necessarily
1192/// its normal location.
1193///
1194/// \param init the initializing expression
1195/// \param var the variable to act as if we're initializing
1196/// \param loc the address to initialize; its type is a pointer
1197///   to the LLVM mapping of the variable's type
1198/// \param alignment the alignment of the address
1199/// \param capturedByInit true if the variable is a __block variable
1200///   whose address is potentially changed by the initializer
1201void CodeGenFunction::EmitExprAsInit(const Expr *init, const ValueDecl *D,
1202                                     LValue lvalue, bool capturedByInit) {
1203  QualType type = D->getType();
1204
1205  if (type->isReferenceType()) {
1206    RValue rvalue = EmitReferenceBindingToExpr(init);
1207    if (capturedByInit)
1208      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
1209    EmitStoreThroughLValue(rvalue, lvalue, true);
1210    return;
1211  }
1212  switch (getEvaluationKind(type)) {
1213  case TEK_Scalar:
1214    EmitScalarInit(init, D, lvalue, capturedByInit);
1215    return;
1216  case TEK_Complex: {
1217    ComplexPairTy complex = EmitComplexExpr(init);
1218    if (capturedByInit)
1219      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
1220    EmitStoreOfComplex(complex, lvalue, /*init*/ true);
1221    return;
1222  }
1223  case TEK_Aggregate:
1224    if (type->isAtomicType()) {
1225      EmitAtomicInit(const_cast<Expr*>(init), lvalue);
1226    } else {
1227      // TODO: how can we delay here if D is captured by its initializer?
1228      EmitAggExpr(init, AggValueSlot::forLValue(lvalue,
1229                                              AggValueSlot::IsDestructed,
1230                                         AggValueSlot::DoesNotNeedGCBarriers,
1231                                              AggValueSlot::IsNotAliased));
1232    }
1233    return;
1234  }
1235  llvm_unreachable("bad evaluation kind");
1236}
1237
1238/// Enter a destroy cleanup for the given local variable.
1239void CodeGenFunction::emitAutoVarTypeCleanup(
1240                            const CodeGenFunction::AutoVarEmission &emission,
1241                            QualType::DestructionKind dtorKind) {
1242  assert(dtorKind != QualType::DK_none);
1243
1244  // Note that for __block variables, we want to destroy the
1245  // original stack object, not the possibly forwarded object.
1246  llvm::Value *addr = emission.getObjectAddress(*this);
1247
1248  const VarDecl *var = emission.Variable;
1249  QualType type = var->getType();
1250
1251  CleanupKind cleanupKind = NormalAndEHCleanup;
1252  CodeGenFunction::Destroyer *destroyer = nullptr;
1253
1254  switch (dtorKind) {
1255  case QualType::DK_none:
1256    llvm_unreachable("no cleanup for trivially-destructible variable");
1257
1258  case QualType::DK_cxx_destructor:
1259    // If there's an NRVO flag on the emission, we need a different
1260    // cleanup.
1261    if (emission.NRVOFlag) {
1262      assert(!type->isArrayType());
1263      CXXDestructorDecl *dtor = type->getAsCXXRecordDecl()->getDestructor();
1264      EHStack.pushCleanup<DestroyNRVOVariable>(cleanupKind, addr, dtor,
1265                                               emission.NRVOFlag);
1266      return;
1267    }
1268    break;
1269
1270  case QualType::DK_objc_strong_lifetime:
1271    // Suppress cleanups for pseudo-strong variables.
1272    if (var->isARCPseudoStrong()) return;
1273
1274    // Otherwise, consider whether to use an EH cleanup or not.
1275    cleanupKind = getARCCleanupKind();
1276
1277    // Use the imprecise destroyer by default.
1278    if (!var->hasAttr<ObjCPreciseLifetimeAttr>())
1279      destroyer = CodeGenFunction::destroyARCStrongImprecise;
1280    break;
1281
1282  case QualType::DK_objc_weak_lifetime:
1283    break;
1284  }
1285
1286  // If we haven't chosen a more specific destroyer, use the default.
1287  if (!destroyer) destroyer = getDestroyer(dtorKind);
1288
1289  // Use an EH cleanup in array destructors iff the destructor itself
1290  // is being pushed as an EH cleanup.
1291  bool useEHCleanup = (cleanupKind & EHCleanup);
1292  EHStack.pushCleanup<DestroyObject>(cleanupKind, addr, type, destroyer,
1293                                     useEHCleanup);
1294}
1295
1296void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) {
1297  assert(emission.Variable && "emission was not valid!");
1298
1299  // If this was emitted as a global constant, we're done.
1300  if (emission.wasEmittedAsGlobal()) return;
1301
1302  // If we don't have an insertion point, we're done.  Sema prevents
1303  // us from jumping into any of these scopes anyway.
1304  if (!HaveInsertPoint()) return;
1305
1306  const VarDecl &D = *emission.Variable;
1307
1308  // Make sure we call @llvm.lifetime.end.  This needs to happen
1309  // *last*, so the cleanup needs to be pushed *first*.
1310  if (emission.useLifetimeMarkers()) {
1311    EHStack.pushCleanup<CallLifetimeEnd>(NormalCleanup,
1312                                         emission.getAllocatedAddress(),
1313                                         emission.getSizeForLifetimeMarkers());
1314  }
1315
1316  // Check the type for a cleanup.
1317  if (QualType::DestructionKind dtorKind = D.getType().isDestructedType())
1318    emitAutoVarTypeCleanup(emission, dtorKind);
1319
1320  // In GC mode, honor objc_precise_lifetime.
1321  if (getLangOpts().getGC() != LangOptions::NonGC &&
1322      D.hasAttr<ObjCPreciseLifetimeAttr>()) {
1323    EHStack.pushCleanup<ExtendGCLifetime>(NormalCleanup, &D);
1324  }
1325
1326  // Handle the cleanup attribute.
1327  if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) {
1328    const FunctionDecl *FD = CA->getFunctionDecl();
1329
1330    llvm::Constant *F = CGM.GetAddrOfFunction(FD);
1331    assert(F && "Could not find function!");
1332
1333    const CGFunctionInfo &Info = CGM.getTypes().arrangeFunctionDeclaration(FD);
1334    EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup, F, &Info, &D);
1335  }
1336
1337  // If this is a block variable, call _Block_object_destroy
1338  // (on the unforwarded address).
1339  if (emission.IsByRef)
1340    enterByrefCleanup(emission);
1341}
1342
1343CodeGenFunction::Destroyer *
1344CodeGenFunction::getDestroyer(QualType::DestructionKind kind) {
1345  switch (kind) {
1346  case QualType::DK_none: llvm_unreachable("no destroyer for trivial dtor");
1347  case QualType::DK_cxx_destructor:
1348    return destroyCXXObject;
1349  case QualType::DK_objc_strong_lifetime:
1350    return destroyARCStrongPrecise;
1351  case QualType::DK_objc_weak_lifetime:
1352    return destroyARCWeak;
1353  }
1354  llvm_unreachable("Unknown DestructionKind");
1355}
1356
1357/// pushEHDestroy - Push the standard destructor for the given type as
1358/// an EH-only cleanup.
1359void CodeGenFunction::pushEHDestroy(QualType::DestructionKind dtorKind,
1360                                  llvm::Value *addr, QualType type) {
1361  assert(dtorKind && "cannot push destructor for trivial type");
1362  assert(needsEHCleanup(dtorKind));
1363
1364  pushDestroy(EHCleanup, addr, type, getDestroyer(dtorKind), true);
1365}
1366
1367/// pushDestroy - Push the standard destructor for the given type as
1368/// at least a normal cleanup.
1369void CodeGenFunction::pushDestroy(QualType::DestructionKind dtorKind,
1370                                  llvm::Value *addr, QualType type) {
1371  assert(dtorKind && "cannot push destructor for trivial type");
1372
1373  CleanupKind cleanupKind = getCleanupKind(dtorKind);
1374  pushDestroy(cleanupKind, addr, type, getDestroyer(dtorKind),
1375              cleanupKind & EHCleanup);
1376}
1377
1378void CodeGenFunction::pushDestroy(CleanupKind cleanupKind, llvm::Value *addr,
1379                                  QualType type, Destroyer *destroyer,
1380                                  bool useEHCleanupForArray) {
1381  pushFullExprCleanup<DestroyObject>(cleanupKind, addr, type,
1382                                     destroyer, useEHCleanupForArray);
1383}
1384
1385void CodeGenFunction::pushStackRestore(CleanupKind Kind, llvm::Value *SPMem) {
1386  EHStack.pushCleanup<CallStackRestore>(Kind, SPMem);
1387}
1388
1389void CodeGenFunction::pushLifetimeExtendedDestroy(
1390    CleanupKind cleanupKind, llvm::Value *addr, QualType type,
1391    Destroyer *destroyer, bool useEHCleanupForArray) {
1392  assert(!isInConditionalBranch() &&
1393         "performing lifetime extension from within conditional");
1394
1395  // Push an EH-only cleanup for the object now.
1396  // FIXME: When popping normal cleanups, we need to keep this EH cleanup
1397  // around in case a temporary's destructor throws an exception.
1398  if (cleanupKind & EHCleanup)
1399    EHStack.pushCleanup<DestroyObject>(
1400        static_cast<CleanupKind>(cleanupKind & ~NormalCleanup), addr, type,
1401        destroyer, useEHCleanupForArray);
1402
1403  // Remember that we need to push a full cleanup for the object at the
1404  // end of the full-expression.
1405  pushCleanupAfterFullExpr<DestroyObject>(
1406      cleanupKind, addr, type, destroyer, useEHCleanupForArray);
1407}
1408
1409/// emitDestroy - Immediately perform the destruction of the given
1410/// object.
1411///
1412/// \param addr - the address of the object; a type*
1413/// \param type - the type of the object; if an array type, all
1414///   objects are destroyed in reverse order
1415/// \param destroyer - the function to call to destroy individual
1416///   elements
1417/// \param useEHCleanupForArray - whether an EH cleanup should be
1418///   used when destroying array elements, in case one of the
1419///   destructions throws an exception
1420void CodeGenFunction::emitDestroy(llvm::Value *addr, QualType type,
1421                                  Destroyer *destroyer,
1422                                  bool useEHCleanupForArray) {
1423  const ArrayType *arrayType = getContext().getAsArrayType(type);
1424  if (!arrayType)
1425    return destroyer(*this, addr, type);
1426
1427  llvm::Value *begin = addr;
1428  llvm::Value *length = emitArrayLength(arrayType, type, begin);
1429
1430  // Normally we have to check whether the array is zero-length.
1431  bool checkZeroLength = true;
1432
1433  // But if the array length is constant, we can suppress that.
1434  if (llvm::ConstantInt *constLength = dyn_cast<llvm::ConstantInt>(length)) {
1435    // ...and if it's constant zero, we can just skip the entire thing.
1436    if (constLength->isZero()) return;
1437    checkZeroLength = false;
1438  }
1439
1440  llvm::Value *end = Builder.CreateInBoundsGEP(begin, length);
1441  emitArrayDestroy(begin, end, type, destroyer,
1442                   checkZeroLength, useEHCleanupForArray);
1443}
1444
1445/// emitArrayDestroy - Destroys all the elements of the given array,
1446/// beginning from last to first.  The array cannot be zero-length.
1447///
1448/// \param begin - a type* denoting the first element of the array
1449/// \param end - a type* denoting one past the end of the array
1450/// \param type - the element type of the array
1451/// \param destroyer - the function to call to destroy elements
1452/// \param useEHCleanup - whether to push an EH cleanup to destroy
1453///   the remaining elements in case the destruction of a single
1454///   element throws
1455void CodeGenFunction::emitArrayDestroy(llvm::Value *begin,
1456                                       llvm::Value *end,
1457                                       QualType type,
1458                                       Destroyer *destroyer,
1459                                       bool checkZeroLength,
1460                                       bool useEHCleanup) {
1461  assert(!type->isArrayType());
1462
1463  // The basic structure here is a do-while loop, because we don't
1464  // need to check for the zero-element case.
1465  llvm::BasicBlock *bodyBB = createBasicBlock("arraydestroy.body");
1466  llvm::BasicBlock *doneBB = createBasicBlock("arraydestroy.done");
1467
1468  if (checkZeroLength) {
1469    llvm::Value *isEmpty = Builder.CreateICmpEQ(begin, end,
1470                                                "arraydestroy.isempty");
1471    Builder.CreateCondBr(isEmpty, doneBB, bodyBB);
1472  }
1473
1474  // Enter the loop body, making that address the current address.
1475  llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
1476  EmitBlock(bodyBB);
1477  llvm::PHINode *elementPast =
1478    Builder.CreatePHI(begin->getType(), 2, "arraydestroy.elementPast");
1479  elementPast->addIncoming(end, entryBB);
1480
1481  // Shift the address back by one element.
1482  llvm::Value *negativeOne = llvm::ConstantInt::get(SizeTy, -1, true);
1483  llvm::Value *element = Builder.CreateInBoundsGEP(elementPast, negativeOne,
1484                                                   "arraydestroy.element");
1485
1486  if (useEHCleanup)
1487    pushRegularPartialArrayCleanup(begin, element, type, destroyer);
1488
1489  // Perform the actual destruction there.
1490  destroyer(*this, element, type);
1491
1492  if (useEHCleanup)
1493    PopCleanupBlock();
1494
1495  // Check whether we've reached the end.
1496  llvm::Value *done = Builder.CreateICmpEQ(element, begin, "arraydestroy.done");
1497  Builder.CreateCondBr(done, doneBB, bodyBB);
1498  elementPast->addIncoming(element, Builder.GetInsertBlock());
1499
1500  // Done.
1501  EmitBlock(doneBB);
1502}
1503
1504/// Perform partial array destruction as if in an EH cleanup.  Unlike
1505/// emitArrayDestroy, the element type here may still be an array type.
1506static void emitPartialArrayDestroy(CodeGenFunction &CGF,
1507                                    llvm::Value *begin, llvm::Value *end,
1508                                    QualType type,
1509                                    CodeGenFunction::Destroyer *destroyer) {
1510  // If the element type is itself an array, drill down.
1511  unsigned arrayDepth = 0;
1512  while (const ArrayType *arrayType = CGF.getContext().getAsArrayType(type)) {
1513    // VLAs don't require a GEP index to walk into.
1514    if (!isa<VariableArrayType>(arrayType))
1515      arrayDepth++;
1516    type = arrayType->getElementType();
1517  }
1518
1519  if (arrayDepth) {
1520    llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, arrayDepth+1);
1521
1522    SmallVector<llvm::Value*,4> gepIndices(arrayDepth, zero);
1523    begin = CGF.Builder.CreateInBoundsGEP(begin, gepIndices, "pad.arraybegin");
1524    end = CGF.Builder.CreateInBoundsGEP(end, gepIndices, "pad.arrayend");
1525  }
1526
1527  // Destroy the array.  We don't ever need an EH cleanup because we
1528  // assume that we're in an EH cleanup ourselves, so a throwing
1529  // destructor causes an immediate terminate.
1530  CGF.emitArrayDestroy(begin, end, type, destroyer,
1531                       /*checkZeroLength*/ true, /*useEHCleanup*/ false);
1532}
1533
1534namespace {
1535  /// RegularPartialArrayDestroy - a cleanup which performs a partial
1536  /// array destroy where the end pointer is regularly determined and
1537  /// does not need to be loaded from a local.
1538  class RegularPartialArrayDestroy : public EHScopeStack::Cleanup {
1539    llvm::Value *ArrayBegin;
1540    llvm::Value *ArrayEnd;
1541    QualType ElementType;
1542    CodeGenFunction::Destroyer *Destroyer;
1543  public:
1544    RegularPartialArrayDestroy(llvm::Value *arrayBegin, llvm::Value *arrayEnd,
1545                               QualType elementType,
1546                               CodeGenFunction::Destroyer *destroyer)
1547      : ArrayBegin(arrayBegin), ArrayEnd(arrayEnd),
1548        ElementType(elementType), Destroyer(destroyer) {}
1549
1550    void Emit(CodeGenFunction &CGF, Flags flags) override {
1551      emitPartialArrayDestroy(CGF, ArrayBegin, ArrayEnd,
1552                              ElementType, Destroyer);
1553    }
1554  };
1555
1556  /// IrregularPartialArrayDestroy - a cleanup which performs a
1557  /// partial array destroy where the end pointer is irregularly
1558  /// determined and must be loaded from a local.
1559  class IrregularPartialArrayDestroy : public EHScopeStack::Cleanup {
1560    llvm::Value *ArrayBegin;
1561    llvm::Value *ArrayEndPointer;
1562    QualType ElementType;
1563    CodeGenFunction::Destroyer *Destroyer;
1564  public:
1565    IrregularPartialArrayDestroy(llvm::Value *arrayBegin,
1566                                 llvm::Value *arrayEndPointer,
1567                                 QualType elementType,
1568                                 CodeGenFunction::Destroyer *destroyer)
1569      : ArrayBegin(arrayBegin), ArrayEndPointer(arrayEndPointer),
1570        ElementType(elementType), Destroyer(destroyer) {}
1571
1572    void Emit(CodeGenFunction &CGF, Flags flags) override {
1573      llvm::Value *arrayEnd = CGF.Builder.CreateLoad(ArrayEndPointer);
1574      emitPartialArrayDestroy(CGF, ArrayBegin, arrayEnd,
1575                              ElementType, Destroyer);
1576    }
1577  };
1578}
1579
1580/// pushIrregularPartialArrayCleanup - Push an EH cleanup to destroy
1581/// already-constructed elements of the given array.  The cleanup
1582/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
1583///
1584/// \param elementType - the immediate element type of the array;
1585///   possibly still an array type
1586void CodeGenFunction::pushIrregularPartialArrayCleanup(llvm::Value *arrayBegin,
1587                                                 llvm::Value *arrayEndPointer,
1588                                                       QualType elementType,
1589                                                       Destroyer *destroyer) {
1590  pushFullExprCleanup<IrregularPartialArrayDestroy>(EHCleanup,
1591                                                    arrayBegin, arrayEndPointer,
1592                                                    elementType, destroyer);
1593}
1594
1595/// pushRegularPartialArrayCleanup - Push an EH cleanup to destroy
1596/// already-constructed elements of the given array.  The cleanup
1597/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
1598///
1599/// \param elementType - the immediate element type of the array;
1600///   possibly still an array type
1601void CodeGenFunction::pushRegularPartialArrayCleanup(llvm::Value *arrayBegin,
1602                                                     llvm::Value *arrayEnd,
1603                                                     QualType elementType,
1604                                                     Destroyer *destroyer) {
1605  pushFullExprCleanup<RegularPartialArrayDestroy>(EHCleanup,
1606                                                  arrayBegin, arrayEnd,
1607                                                  elementType, destroyer);
1608}
1609
1610/// Lazily declare the @llvm.lifetime.start intrinsic.
1611llvm::Constant *CodeGenModule::getLLVMLifetimeStartFn() {
1612  if (LifetimeStartFn) return LifetimeStartFn;
1613  LifetimeStartFn = llvm::Intrinsic::getDeclaration(&getModule(),
1614                                            llvm::Intrinsic::lifetime_start);
1615  return LifetimeStartFn;
1616}
1617
1618/// Lazily declare the @llvm.lifetime.end intrinsic.
1619llvm::Constant *CodeGenModule::getLLVMLifetimeEndFn() {
1620  if (LifetimeEndFn) return LifetimeEndFn;
1621  LifetimeEndFn = llvm::Intrinsic::getDeclaration(&getModule(),
1622                                              llvm::Intrinsic::lifetime_end);
1623  return LifetimeEndFn;
1624}
1625
1626namespace {
1627  /// A cleanup to perform a release of an object at the end of a
1628  /// function.  This is used to balance out the incoming +1 of a
1629  /// ns_consumed argument when we can't reasonably do that just by
1630  /// not doing the initial retain for a __block argument.
1631  struct ConsumeARCParameter : EHScopeStack::Cleanup {
1632    ConsumeARCParameter(llvm::Value *param,
1633                        ARCPreciseLifetime_t precise)
1634      : Param(param), Precise(precise) {}
1635
1636    llvm::Value *Param;
1637    ARCPreciseLifetime_t Precise;
1638
1639    void Emit(CodeGenFunction &CGF, Flags flags) override {
1640      CGF.EmitARCRelease(Param, Precise);
1641    }
1642  };
1643}
1644
1645/// Emit an alloca (or GlobalValue depending on target)
1646/// for the specified parameter and set up LocalDeclMap.
1647void CodeGenFunction::EmitParmDecl(const VarDecl &D, llvm::Value *Arg,
1648                                   bool ArgIsPointer, unsigned ArgNo) {
1649  // FIXME: Why isn't ImplicitParamDecl a ParmVarDecl?
1650  assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) &&
1651         "Invalid argument to EmitParmDecl");
1652
1653  Arg->setName(D.getName());
1654
1655  QualType Ty = D.getType();
1656
1657  // Use better IR generation for certain implicit parameters.
1658  if (isa<ImplicitParamDecl>(D)) {
1659    // The only implicit argument a block has is its literal.
1660    if (BlockInfo) {
1661      LocalDeclMap[&D] = Arg;
1662      llvm::Value *LocalAddr = nullptr;
1663      if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
1664        // Allocate a stack slot to let the debug info survive the RA.
1665        llvm::AllocaInst *Alloc = CreateTempAlloca(ConvertTypeForMem(Ty),
1666                                                   D.getName() + ".addr");
1667        Alloc->setAlignment(getContext().getDeclAlign(&D).getQuantity());
1668        LValue lv = MakeAddrLValue(Alloc, Ty, getContext().getDeclAlign(&D));
1669        EmitStoreOfScalar(Arg, lv, /* isInitialization */ true);
1670        LocalAddr = Builder.CreateLoad(Alloc);
1671      }
1672
1673      if (CGDebugInfo *DI = getDebugInfo()) {
1674        if (CGM.getCodeGenOpts().getDebugInfo()
1675              >= CodeGenOptions::LimitedDebugInfo) {
1676          DI->setLocation(D.getLocation());
1677          DI->EmitDeclareOfBlockLiteralArgVariable(*BlockInfo, Arg, ArgNo,
1678                                                   LocalAddr, Builder);
1679        }
1680      }
1681
1682      return;
1683    }
1684  }
1685
1686  llvm::Value *DeclPtr;
1687  bool DoStore = false;
1688  bool IsScalar = hasScalarEvaluationKind(Ty);
1689  CharUnits Align = getContext().getDeclAlign(&D);
1690  // If we already have a pointer to the argument, reuse the input pointer.
1691  if (ArgIsPointer) {
1692    // If we have a prettier pointer type at this point, bitcast to that.
1693    unsigned AS = cast<llvm::PointerType>(Arg->getType())->getAddressSpace();
1694    llvm::Type *IRTy = ConvertTypeForMem(Ty)->getPointerTo(AS);
1695    DeclPtr = Arg->getType() == IRTy ? Arg : Builder.CreateBitCast(Arg, IRTy,
1696                                                                   D.getName());
1697    // Push a destructor cleanup for this parameter if the ABI requires it.
1698    // Don't push a cleanup in a thunk for a method that will also emit a
1699    // cleanup.
1700    if (!IsScalar && !CurFuncIsThunk &&
1701        getTarget().getCXXABI().areArgsDestroyedLeftToRightInCallee()) {
1702      const CXXRecordDecl *RD = Ty->getAsCXXRecordDecl();
1703      if (RD && RD->hasNonTrivialDestructor())
1704        pushDestroy(QualType::DK_cxx_destructor, DeclPtr, Ty);
1705    }
1706  } else {
1707    // Otherwise, create a temporary to hold the value.
1708    llvm::AllocaInst *Alloc = CreateTempAlloca(ConvertTypeForMem(Ty),
1709                                               D.getName() + ".addr");
1710    Alloc->setAlignment(Align.getQuantity());
1711    DeclPtr = Alloc;
1712    DoStore = true;
1713  }
1714
1715  LValue lv = MakeAddrLValue(DeclPtr, Ty, Align);
1716  if (IsScalar) {
1717    Qualifiers qs = Ty.getQualifiers();
1718    if (Qualifiers::ObjCLifetime lt = qs.getObjCLifetime()) {
1719      // We honor __attribute__((ns_consumed)) for types with lifetime.
1720      // For __strong, it's handled by just skipping the initial retain;
1721      // otherwise we have to balance out the initial +1 with an extra
1722      // cleanup to do the release at the end of the function.
1723      bool isConsumed = D.hasAttr<NSConsumedAttr>();
1724
1725      // 'self' is always formally __strong, but if this is not an
1726      // init method then we don't want to retain it.
1727      if (D.isARCPseudoStrong()) {
1728        const ObjCMethodDecl *method = cast<ObjCMethodDecl>(CurCodeDecl);
1729        assert(&D == method->getSelfDecl());
1730        assert(lt == Qualifiers::OCL_Strong);
1731        assert(qs.hasConst());
1732        assert(method->getMethodFamily() != OMF_init);
1733        (void) method;
1734        lt = Qualifiers::OCL_ExplicitNone;
1735      }
1736
1737      if (lt == Qualifiers::OCL_Strong) {
1738        if (!isConsumed) {
1739          if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
1740            // use objc_storeStrong(&dest, value) for retaining the
1741            // object. But first, store a null into 'dest' because
1742            // objc_storeStrong attempts to release its old value.
1743            llvm::Value *Null = CGM.EmitNullConstant(D.getType());
1744            EmitStoreOfScalar(Null, lv, /* isInitialization */ true);
1745            EmitARCStoreStrongCall(lv.getAddress(), Arg, true);
1746            DoStore = false;
1747          }
1748          else
1749          // Don't use objc_retainBlock for block pointers, because we
1750          // don't want to Block_copy something just because we got it
1751          // as a parameter.
1752            Arg = EmitARCRetainNonBlock(Arg);
1753        }
1754      } else {
1755        // Push the cleanup for a consumed parameter.
1756        if (isConsumed) {
1757          ARCPreciseLifetime_t precise = (D.hasAttr<ObjCPreciseLifetimeAttr>()
1758                                ? ARCPreciseLifetime : ARCImpreciseLifetime);
1759          EHStack.pushCleanup<ConsumeARCParameter>(getARCCleanupKind(), Arg,
1760                                                   precise);
1761        }
1762
1763        if (lt == Qualifiers::OCL_Weak) {
1764          EmitARCInitWeak(DeclPtr, Arg);
1765          DoStore = false; // The weak init is a store, no need to do two.
1766        }
1767      }
1768
1769      // Enter the cleanup scope.
1770      EmitAutoVarWithLifetime(*this, D, DeclPtr, lt);
1771    }
1772  }
1773
1774  // Store the initial value into the alloca.
1775  if (DoStore)
1776    EmitStoreOfScalar(Arg, lv, /* isInitialization */ true);
1777
1778  llvm::Value *&DMEntry = LocalDeclMap[&D];
1779  assert(!DMEntry && "Decl already exists in localdeclmap!");
1780  DMEntry = DeclPtr;
1781
1782  // Emit debug info for param declaration.
1783  if (CGDebugInfo *DI = getDebugInfo()) {
1784    if (CGM.getCodeGenOpts().getDebugInfo()
1785          >= CodeGenOptions::LimitedDebugInfo) {
1786      DI->EmitDeclareOfArgVariable(&D, DeclPtr, ArgNo, Builder);
1787    }
1788  }
1789
1790  if (D.hasAttr<AnnotateAttr>())
1791      EmitVarAnnotations(&D, DeclPtr);
1792}
1793