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 "CGBlocks.h"
16#include "CGCleanup.h"
17#include "CGDebugInfo.h"
18#include "CGOpenCLRuntime.h"
19#include "CGOpenMPRuntime.h"
20#include "CodeGenModule.h"
21#include "clang/AST/ASTContext.h"
22#include "clang/AST/CharUnits.h"
23#include "clang/AST/Decl.h"
24#include "clang/AST/DeclObjC.h"
25#include "clang/AST/DeclOpenMP.h"
26#include "clang/Basic/SourceManager.h"
27#include "clang/Basic/TargetInfo.h"
28#include "clang/CodeGen/CGFunctionInfo.h"
29#include "clang/Frontend/CodeGenOptions.h"
30#include "llvm/IR/DataLayout.h"
31#include "llvm/IR/GlobalVariable.h"
32#include "llvm/IR/Intrinsics.h"
33#include "llvm/IR/Type.h"
34
35using namespace clang;
36using namespace CodeGen;
37
38void CodeGenFunction::EmitDecl(const Decl &D) {
39  switch (D.getKind()) {
40  case Decl::BuiltinTemplate:
41  case Decl::TranslationUnit:
42  case Decl::ExternCContext:
43  case Decl::Namespace:
44  case Decl::UnresolvedUsingTypename:
45  case Decl::ClassTemplateSpecialization:
46  case Decl::ClassTemplatePartialSpecialization:
47  case Decl::VarTemplateSpecialization:
48  case Decl::VarTemplatePartialSpecialization:
49  case Decl::TemplateTypeParm:
50  case Decl::UnresolvedUsingValue:
51  case Decl::NonTypeTemplateParm:
52  case Decl::CXXMethod:
53  case Decl::CXXConstructor:
54  case Decl::CXXDestructor:
55  case Decl::CXXConversion:
56  case Decl::Field:
57  case Decl::MSProperty:
58  case Decl::IndirectField:
59  case Decl::ObjCIvar:
60  case Decl::ObjCAtDefsField:
61  case Decl::ParmVar:
62  case Decl::ImplicitParam:
63  case Decl::ClassTemplate:
64  case Decl::VarTemplate:
65  case Decl::FunctionTemplate:
66  case Decl::TypeAliasTemplate:
67  case Decl::TemplateTemplateParm:
68  case Decl::ObjCMethod:
69  case Decl::ObjCCategory:
70  case Decl::ObjCProtocol:
71  case Decl::ObjCInterface:
72  case Decl::ObjCCategoryImpl:
73  case Decl::ObjCImplementation:
74  case Decl::ObjCProperty:
75  case Decl::ObjCCompatibleAlias:
76  case Decl::PragmaComment:
77  case Decl::PragmaDetectMismatch:
78  case Decl::AccessSpec:
79  case Decl::LinkageSpec:
80  case Decl::ObjCPropertyImpl:
81  case Decl::FileScopeAsm:
82  case Decl::Friend:
83  case Decl::FriendTemplate:
84  case Decl::Block:
85  case Decl::Captured:
86  case Decl::ClassScopeFunctionSpecialization:
87  case Decl::UsingShadow:
88  case Decl::ConstructorUsingShadow:
89  case Decl::ObjCTypeParam:
90    llvm_unreachable("Declaration should not be in declstmts!");
91  case Decl::Function:  // void X();
92  case Decl::Record:    // struct/union/class X;
93  case Decl::Enum:      // enum X;
94  case Decl::EnumConstant: // enum ? { X = ? }
95  case Decl::CXXRecord: // struct/union/class X; [C++]
96  case Decl::StaticAssert: // static_assert(X, ""); [C++0x]
97  case Decl::Label:        // __label__ x;
98  case Decl::Import:
99  case Decl::OMPThreadPrivate:
100  case Decl::OMPCapturedExpr:
101  case Decl::Empty:
102    // None of these decls require codegen support.
103    return;
104
105  case Decl::NamespaceAlias:
106    if (CGDebugInfo *DI = getDebugInfo())
107        DI->EmitNamespaceAlias(cast<NamespaceAliasDecl>(D));
108    return;
109  case Decl::Using:          // using X; [C++]
110    if (CGDebugInfo *DI = getDebugInfo())
111        DI->EmitUsingDecl(cast<UsingDecl>(D));
112    return;
113  case Decl::UsingDirective: // using namespace X; [C++]
114    if (CGDebugInfo *DI = getDebugInfo())
115      DI->EmitUsingDirective(cast<UsingDirectiveDecl>(D));
116    return;
117  case Decl::Var: {
118    const VarDecl &VD = cast<VarDecl>(D);
119    assert(VD.isLocalVarDecl() &&
120           "Should not see file-scope variables inside a function!");
121    return EmitVarDecl(VD);
122  }
123
124  case Decl::OMPDeclareReduction:
125    return CGM.EmitOMPDeclareReduction(cast<OMPDeclareReductionDecl>(&D), this);
126
127  case Decl::Typedef:      // typedef int X;
128  case Decl::TypeAlias: {  // using X = int; [C++0x]
129    const TypedefNameDecl &TD = cast<TypedefNameDecl>(D);
130    QualType Ty = TD.getUnderlyingType();
131
132    if (Ty->isVariablyModifiedType())
133      EmitVariablyModifiedType(Ty);
134  }
135  }
136}
137
138/// EmitVarDecl - This method handles emission of any variable declaration
139/// inside a function, including static vars etc.
140void CodeGenFunction::EmitVarDecl(const VarDecl &D) {
141  if (D.isStaticLocal()) {
142    llvm::GlobalValue::LinkageTypes Linkage =
143        CGM.getLLVMLinkageVarDefinition(&D, /*isConstant=*/false);
144
145    // FIXME: We need to force the emission/use of a guard variable for
146    // some variables even if we can constant-evaluate them because
147    // we can't guarantee every translation unit will constant-evaluate them.
148
149    return EmitStaticVarDecl(D, Linkage);
150  }
151
152  if (D.hasExternalStorage())
153    // Don't emit it now, allow it to be emitted lazily on its first use.
154    return;
155
156  if (D.getType().getAddressSpace() == LangAS::opencl_local)
157    return CGM.getOpenCLRuntime().EmitWorkGroupLocalVarDecl(*this, D);
158
159  assert(D.hasLocalStorage());
160  return EmitAutoVarDecl(D);
161}
162
163static std::string getStaticDeclName(CodeGenModule &CGM, const VarDecl &D) {
164  if (CGM.getLangOpts().CPlusPlus)
165    return CGM.getMangledName(&D).str();
166
167  // If this isn't C++, we don't need a mangled name, just a pretty one.
168  assert(!D.isExternallyVisible() && "name shouldn't matter");
169  std::string ContextName;
170  const DeclContext *DC = D.getDeclContext();
171  if (auto *CD = dyn_cast<CapturedDecl>(DC))
172    DC = cast<DeclContext>(CD->getNonClosureContext());
173  if (const auto *FD = dyn_cast<FunctionDecl>(DC))
174    ContextName = CGM.getMangledName(FD);
175  else if (const auto *BD = dyn_cast<BlockDecl>(DC))
176    ContextName = CGM.getBlockMangledName(GlobalDecl(), BD);
177  else if (const auto *OMD = dyn_cast<ObjCMethodDecl>(DC))
178    ContextName = OMD->getSelector().getAsString();
179  else
180    llvm_unreachable("Unknown context for static var decl");
181
182  ContextName += "." + D.getNameAsString();
183  return ContextName;
184}
185
186llvm::Constant *CodeGenModule::getOrCreateStaticVarDecl(
187    const VarDecl &D, llvm::GlobalValue::LinkageTypes Linkage) {
188  // In general, we don't always emit static var decls once before we reference
189  // them. It is possible to reference them before emitting the function that
190  // contains them, and it is possible to emit the containing function multiple
191  // times.
192  if (llvm::Constant *ExistingGV = StaticLocalDeclMap[&D])
193    return ExistingGV;
194
195  QualType Ty = D.getType();
196  assert(Ty->isConstantSizeType() && "VLAs can't be static");
197
198  // Use the label if the variable is renamed with the asm-label extension.
199  std::string Name;
200  if (D.hasAttr<AsmLabelAttr>())
201    Name = getMangledName(&D);
202  else
203    Name = getStaticDeclName(*this, D);
204
205  llvm::Type *LTy = getTypes().ConvertTypeForMem(Ty);
206  unsigned AddrSpace =
207      GetGlobalVarAddressSpace(&D, getContext().getTargetAddressSpace(Ty));
208
209  // Local address space cannot have an initializer.
210  llvm::Constant *Init = nullptr;
211  if (Ty.getAddressSpace() != LangAS::opencl_local)
212    Init = EmitNullConstant(Ty);
213  else
214    Init = llvm::UndefValue::get(LTy);
215
216  llvm::GlobalVariable *GV =
217    new llvm::GlobalVariable(getModule(), LTy,
218                             Ty.isConstant(getContext()), Linkage,
219                             Init, Name, nullptr,
220                             llvm::GlobalVariable::NotThreadLocal,
221                             AddrSpace);
222  GV->setAlignment(getContext().getDeclAlign(&D).getQuantity());
223  setGlobalVisibility(GV, &D);
224
225  if (supportsCOMDAT() && GV->isWeakForLinker())
226    GV->setComdat(TheModule.getOrInsertComdat(GV->getName()));
227
228  if (D.getTLSKind())
229    setTLSMode(GV, D);
230
231  if (D.isExternallyVisible()) {
232    if (D.hasAttr<DLLImportAttr>())
233      GV->setDLLStorageClass(llvm::GlobalVariable::DLLImportStorageClass);
234    else if (D.hasAttr<DLLExportAttr>())
235      GV->setDLLStorageClass(llvm::GlobalVariable::DLLExportStorageClass);
236  }
237
238  // Make sure the result is of the correct type.
239  unsigned ExpectedAddrSpace = getContext().getTargetAddressSpace(Ty);
240  llvm::Constant *Addr = GV;
241  if (AddrSpace != ExpectedAddrSpace) {
242    llvm::PointerType *PTy = llvm::PointerType::get(LTy, ExpectedAddrSpace);
243    Addr = llvm::ConstantExpr::getAddrSpaceCast(GV, PTy);
244  }
245
246  setStaticLocalDeclAddress(&D, Addr);
247
248  // Ensure that the static local gets initialized by making sure the parent
249  // function gets emitted eventually.
250  const Decl *DC = cast<Decl>(D.getDeclContext());
251
252  // We can't name blocks or captured statements directly, so try to emit their
253  // parents.
254  if (isa<BlockDecl>(DC) || isa<CapturedDecl>(DC)) {
255    DC = DC->getNonClosureContext();
256    // FIXME: Ensure that global blocks get emitted.
257    if (!DC)
258      return Addr;
259  }
260
261  GlobalDecl GD;
262  if (const auto *CD = dyn_cast<CXXConstructorDecl>(DC))
263    GD = GlobalDecl(CD, Ctor_Base);
264  else if (const auto *DD = dyn_cast<CXXDestructorDecl>(DC))
265    GD = GlobalDecl(DD, Dtor_Base);
266  else if (const auto *FD = dyn_cast<FunctionDecl>(DC))
267    GD = GlobalDecl(FD);
268  else {
269    // Don't do anything for Obj-C method decls or global closures. We should
270    // never defer them.
271    assert(isa<ObjCMethodDecl>(DC) && "unexpected parent code decl");
272  }
273  if (GD.getDecl())
274    (void)GetAddrOfGlobal(GD);
275
276  return Addr;
277}
278
279/// hasNontrivialDestruction - Determine whether a type's destruction is
280/// non-trivial. If so, and the variable uses static initialization, we must
281/// register its destructor to run on exit.
282static bool hasNontrivialDestruction(QualType T) {
283  CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
284  return RD && !RD->hasTrivialDestructor();
285}
286
287/// AddInitializerToStaticVarDecl - Add the initializer for 'D' to the
288/// global variable that has already been created for it.  If the initializer
289/// has a different type than GV does, this may free GV and return a different
290/// one.  Otherwise it just returns GV.
291llvm::GlobalVariable *
292CodeGenFunction::AddInitializerToStaticVarDecl(const VarDecl &D,
293                                               llvm::GlobalVariable *GV) {
294  llvm::Constant *Init = CGM.EmitConstantInit(D, this);
295
296  // If constant emission failed, then this should be a C++ static
297  // initializer.
298  if (!Init) {
299    if (!getLangOpts().CPlusPlus)
300      CGM.ErrorUnsupported(D.getInit(), "constant l-value expression");
301    else if (Builder.GetInsertBlock()) {
302      // Since we have a static initializer, this global variable can't
303      // be constant.
304      GV->setConstant(false);
305
306      EmitCXXGuardedInit(D, GV, /*PerformInit*/true);
307    }
308    return GV;
309  }
310
311  // The initializer may differ in type from the global. Rewrite
312  // the global to match the initializer.  (We have to do this
313  // because some types, like unions, can't be completely represented
314  // in the LLVM type system.)
315  if (GV->getType()->getElementType() != Init->getType()) {
316    llvm::GlobalVariable *OldGV = GV;
317
318    GV = new llvm::GlobalVariable(CGM.getModule(), Init->getType(),
319                                  OldGV->isConstant(),
320                                  OldGV->getLinkage(), Init, "",
321                                  /*InsertBefore*/ OldGV,
322                                  OldGV->getThreadLocalMode(),
323                           CGM.getContext().getTargetAddressSpace(D.getType()));
324    GV->setVisibility(OldGV->getVisibility());
325    GV->setComdat(OldGV->getComdat());
326
327    // Steal the name of the old global
328    GV->takeName(OldGV);
329
330    // Replace all uses of the old global with the new global
331    llvm::Constant *NewPtrForOldDecl =
332    llvm::ConstantExpr::getBitCast(GV, OldGV->getType());
333    OldGV->replaceAllUsesWith(NewPtrForOldDecl);
334
335    // Erase the old global, since it is no longer used.
336    OldGV->eraseFromParent();
337  }
338
339  GV->setConstant(CGM.isTypeConstant(D.getType(), true));
340  GV->setInitializer(Init);
341
342  if (hasNontrivialDestruction(D.getType())) {
343    // We have a constant initializer, but a nontrivial destructor. We still
344    // need to perform a guarded "initialization" in order to register the
345    // destructor.
346    EmitCXXGuardedInit(D, GV, /*PerformInit*/false);
347  }
348
349  return GV;
350}
351
352void CodeGenFunction::EmitStaticVarDecl(const VarDecl &D,
353                                      llvm::GlobalValue::LinkageTypes Linkage) {
354  // Check to see if we already have a global variable for this
355  // declaration.  This can happen when double-emitting function
356  // bodies, e.g. with complete and base constructors.
357  llvm::Constant *addr = CGM.getOrCreateStaticVarDecl(D, Linkage);
358  CharUnits alignment = getContext().getDeclAlign(&D);
359
360  // Store into LocalDeclMap before generating initializer to handle
361  // circular references.
362  setAddrOfLocalVar(&D, Address(addr, alignment));
363
364  // We can't have a VLA here, but we can have a pointer to a VLA,
365  // even though that doesn't really make any sense.
366  // Make sure to evaluate VLA bounds now so that we have them for later.
367  if (D.getType()->isVariablyModifiedType())
368    EmitVariablyModifiedType(D.getType());
369
370  // Save the type in case adding the initializer forces a type change.
371  llvm::Type *expectedType = addr->getType();
372
373  llvm::GlobalVariable *var =
374    cast<llvm::GlobalVariable>(addr->stripPointerCasts());
375
376  // CUDA's local and local static __shared__ variables should not
377  // have any non-empty initializers. This is ensured by Sema.
378  // Whatever initializer such variable may have when it gets here is
379  // a no-op and should not be emitted.
380  bool isCudaSharedVar = getLangOpts().CUDA && getLangOpts().CUDAIsDevice &&
381                         D.hasAttr<CUDASharedAttr>();
382  // If this value has an initializer, emit it.
383  if (D.getInit() && !isCudaSharedVar)
384    var = AddInitializerToStaticVarDecl(D, var);
385
386  var->setAlignment(alignment.getQuantity());
387
388  if (D.hasAttr<AnnotateAttr>())
389    CGM.AddGlobalAnnotations(&D, var);
390
391  if (const SectionAttr *SA = D.getAttr<SectionAttr>())
392    var->setSection(SA->getName());
393
394  if (D.hasAttr<UsedAttr>())
395    CGM.addUsedGlobal(var);
396
397  // We may have to cast the constant because of the initializer
398  // mismatch above.
399  //
400  // FIXME: It is really dangerous to store this in the map; if anyone
401  // RAUW's the GV uses of this constant will be invalid.
402  llvm::Constant *castedAddr =
403    llvm::ConstantExpr::getPointerBitCastOrAddrSpaceCast(var, expectedType);
404  if (var != castedAddr)
405    LocalDeclMap.find(&D)->second = Address(castedAddr, alignment);
406  CGM.setStaticLocalDeclAddress(&D, castedAddr);
407
408  CGM.getSanitizerMetadata()->reportGlobalToASan(var, D);
409
410  // Emit global variable debug descriptor for static vars.
411  CGDebugInfo *DI = getDebugInfo();
412  if (DI &&
413      CGM.getCodeGenOpts().getDebugInfo() >= codegenoptions::LimitedDebugInfo) {
414    DI->setLocation(D.getLocation());
415    DI->EmitGlobalVariable(var, &D);
416  }
417}
418
419namespace {
420  struct DestroyObject final : EHScopeStack::Cleanup {
421    DestroyObject(Address addr, QualType type,
422                  CodeGenFunction::Destroyer *destroyer,
423                  bool useEHCleanupForArray)
424      : addr(addr), type(type), destroyer(destroyer),
425        useEHCleanupForArray(useEHCleanupForArray) {}
426
427    Address addr;
428    QualType type;
429    CodeGenFunction::Destroyer *destroyer;
430    bool useEHCleanupForArray;
431
432    void Emit(CodeGenFunction &CGF, Flags flags) override {
433      // Don't use an EH cleanup recursively from an EH cleanup.
434      bool useEHCleanupForArray =
435        flags.isForNormalCleanup() && this->useEHCleanupForArray;
436
437      CGF.emitDestroy(addr, type, destroyer, useEHCleanupForArray);
438    }
439  };
440
441  struct DestroyNRVOVariable final : EHScopeStack::Cleanup {
442    DestroyNRVOVariable(Address addr,
443                        const CXXDestructorDecl *Dtor,
444                        llvm::Value *NRVOFlag)
445      : Dtor(Dtor), NRVOFlag(NRVOFlag), Loc(addr) {}
446
447    const CXXDestructorDecl *Dtor;
448    llvm::Value *NRVOFlag;
449    Address Loc;
450
451    void Emit(CodeGenFunction &CGF, Flags flags) override {
452      // Along the exceptions path we always execute the dtor.
453      bool NRVO = flags.isForNormalCleanup() && NRVOFlag;
454
455      llvm::BasicBlock *SkipDtorBB = nullptr;
456      if (NRVO) {
457        // If we exited via NRVO, we skip the destructor call.
458        llvm::BasicBlock *RunDtorBB = CGF.createBasicBlock("nrvo.unused");
459        SkipDtorBB = CGF.createBasicBlock("nrvo.skipdtor");
460        llvm::Value *DidNRVO =
461          CGF.Builder.CreateFlagLoad(NRVOFlag, "nrvo.val");
462        CGF.Builder.CreateCondBr(DidNRVO, SkipDtorBB, RunDtorBB);
463        CGF.EmitBlock(RunDtorBB);
464      }
465
466      CGF.EmitCXXDestructorCall(Dtor, Dtor_Complete,
467                                /*ForVirtualBase=*/false,
468                                /*Delegating=*/false,
469                                Loc);
470
471      if (NRVO) CGF.EmitBlock(SkipDtorBB);
472    }
473  };
474
475  struct CallStackRestore final : EHScopeStack::Cleanup {
476    Address Stack;
477    CallStackRestore(Address Stack) : Stack(Stack) {}
478    void Emit(CodeGenFunction &CGF, Flags flags) override {
479      llvm::Value *V = CGF.Builder.CreateLoad(Stack);
480      llvm::Value *F = CGF.CGM.getIntrinsic(llvm::Intrinsic::stackrestore);
481      CGF.Builder.CreateCall(F, V);
482    }
483  };
484
485  struct ExtendGCLifetime final : EHScopeStack::Cleanup {
486    const VarDecl &Var;
487    ExtendGCLifetime(const VarDecl *var) : Var(*var) {}
488
489    void Emit(CodeGenFunction &CGF, Flags flags) override {
490      // Compute the address of the local variable, in case it's a
491      // byref or something.
492      DeclRefExpr DRE(const_cast<VarDecl*>(&Var), false,
493                      Var.getType(), VK_LValue, SourceLocation());
494      llvm::Value *value = CGF.EmitLoadOfScalar(CGF.EmitDeclRefLValue(&DRE),
495                                                SourceLocation());
496      CGF.EmitExtendGCLifetime(value);
497    }
498  };
499
500  struct CallCleanupFunction final : EHScopeStack::Cleanup {
501    llvm::Constant *CleanupFn;
502    const CGFunctionInfo &FnInfo;
503    const VarDecl &Var;
504
505    CallCleanupFunction(llvm::Constant *CleanupFn, const CGFunctionInfo *Info,
506                        const VarDecl *Var)
507      : CleanupFn(CleanupFn), FnInfo(*Info), Var(*Var) {}
508
509    void Emit(CodeGenFunction &CGF, Flags flags) override {
510      DeclRefExpr DRE(const_cast<VarDecl*>(&Var), false,
511                      Var.getType(), VK_LValue, SourceLocation());
512      // Compute the address of the local variable, in case it's a byref
513      // or something.
514      llvm::Value *Addr = CGF.EmitDeclRefLValue(&DRE).getPointer();
515
516      // In some cases, the type of the function argument will be different from
517      // the type of the pointer. An example of this is
518      // void f(void* arg);
519      // __attribute__((cleanup(f))) void *g;
520      //
521      // To fix this we insert a bitcast here.
522      QualType ArgTy = FnInfo.arg_begin()->type;
523      llvm::Value *Arg =
524        CGF.Builder.CreateBitCast(Addr, CGF.ConvertType(ArgTy));
525
526      CallArgList Args;
527      Args.add(RValue::get(Arg),
528               CGF.getContext().getPointerType(Var.getType()));
529      CGF.EmitCall(FnInfo, CleanupFn, ReturnValueSlot(), Args);
530    }
531  };
532} // end anonymous namespace
533
534/// EmitAutoVarWithLifetime - Does the setup required for an automatic
535/// variable with lifetime.
536static void EmitAutoVarWithLifetime(CodeGenFunction &CGF, const VarDecl &var,
537                                    Address addr,
538                                    Qualifiers::ObjCLifetime lifetime) {
539  switch (lifetime) {
540  case Qualifiers::OCL_None:
541    llvm_unreachable("present but none");
542
543  case Qualifiers::OCL_ExplicitNone:
544    // nothing to do
545    break;
546
547  case Qualifiers::OCL_Strong: {
548    CodeGenFunction::Destroyer *destroyer =
549      (var.hasAttr<ObjCPreciseLifetimeAttr>()
550       ? CodeGenFunction::destroyARCStrongPrecise
551       : CodeGenFunction::destroyARCStrongImprecise);
552
553    CleanupKind cleanupKind = CGF.getARCCleanupKind();
554    CGF.pushDestroy(cleanupKind, addr, var.getType(), destroyer,
555                    cleanupKind & EHCleanup);
556    break;
557  }
558  case Qualifiers::OCL_Autoreleasing:
559    // nothing to do
560    break;
561
562  case Qualifiers::OCL_Weak:
563    // __weak objects always get EH cleanups; otherwise, exceptions
564    // could cause really nasty crashes instead of mere leaks.
565    CGF.pushDestroy(NormalAndEHCleanup, addr, var.getType(),
566                    CodeGenFunction::destroyARCWeak,
567                    /*useEHCleanup*/ true);
568    break;
569  }
570}
571
572static bool isAccessedBy(const VarDecl &var, const Stmt *s) {
573  if (const Expr *e = dyn_cast<Expr>(s)) {
574    // Skip the most common kinds of expressions that make
575    // hierarchy-walking expensive.
576    s = e = e->IgnoreParenCasts();
577
578    if (const DeclRefExpr *ref = dyn_cast<DeclRefExpr>(e))
579      return (ref->getDecl() == &var);
580    if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) {
581      const BlockDecl *block = be->getBlockDecl();
582      for (const auto &I : block->captures()) {
583        if (I.getVariable() == &var)
584          return true;
585      }
586    }
587  }
588
589  for (const Stmt *SubStmt : s->children())
590    // SubStmt might be null; as in missing decl or conditional of an if-stmt.
591    if (SubStmt && isAccessedBy(var, SubStmt))
592      return true;
593
594  return false;
595}
596
597static bool isAccessedBy(const ValueDecl *decl, const Expr *e) {
598  if (!decl) return false;
599  if (!isa<VarDecl>(decl)) return false;
600  const VarDecl *var = cast<VarDecl>(decl);
601  return isAccessedBy(*var, e);
602}
603
604static bool tryEmitARCCopyWeakInit(CodeGenFunction &CGF,
605                                   const LValue &destLV, const Expr *init) {
606  bool needsCast = false;
607
608  while (auto castExpr = dyn_cast<CastExpr>(init->IgnoreParens())) {
609    switch (castExpr->getCastKind()) {
610    // Look through casts that don't require representation changes.
611    case CK_NoOp:
612    case CK_BitCast:
613    case CK_BlockPointerToObjCPointerCast:
614      needsCast = true;
615      break;
616
617    // If we find an l-value to r-value cast from a __weak variable,
618    // emit this operation as a copy or move.
619    case CK_LValueToRValue: {
620      const Expr *srcExpr = castExpr->getSubExpr();
621      if (srcExpr->getType().getObjCLifetime() != Qualifiers::OCL_Weak)
622        return false;
623
624      // Emit the source l-value.
625      LValue srcLV = CGF.EmitLValue(srcExpr);
626
627      // Handle a formal type change to avoid asserting.
628      auto srcAddr = srcLV.getAddress();
629      if (needsCast) {
630        srcAddr = CGF.Builder.CreateElementBitCast(srcAddr,
631                                         destLV.getAddress().getElementType());
632      }
633
634      // If it was an l-value, use objc_copyWeak.
635      if (srcExpr->getValueKind() == VK_LValue) {
636        CGF.EmitARCCopyWeak(destLV.getAddress(), srcAddr);
637      } else {
638        assert(srcExpr->getValueKind() == VK_XValue);
639        CGF.EmitARCMoveWeak(destLV.getAddress(), srcAddr);
640      }
641      return true;
642    }
643
644    // Stop at anything else.
645    default:
646      return false;
647    }
648
649    init = castExpr->getSubExpr();
650  }
651  return false;
652}
653
654static void drillIntoBlockVariable(CodeGenFunction &CGF,
655                                   LValue &lvalue,
656                                   const VarDecl *var) {
657  lvalue.setAddress(CGF.emitBlockByrefAddress(lvalue.getAddress(), var));
658}
659
660void CodeGenFunction::EmitScalarInit(const Expr *init, const ValueDecl *D,
661                                     LValue lvalue, bool capturedByInit) {
662  Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
663  if (!lifetime) {
664    llvm::Value *value = EmitScalarExpr(init);
665    if (capturedByInit)
666      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
667    EmitStoreThroughLValue(RValue::get(value), lvalue, true);
668    return;
669  }
670
671  if (const CXXDefaultInitExpr *DIE = dyn_cast<CXXDefaultInitExpr>(init))
672    init = DIE->getExpr();
673
674  // If we're emitting a value with lifetime, we have to do the
675  // initialization *before* we leave the cleanup scopes.
676  if (const ExprWithCleanups *ewc = dyn_cast<ExprWithCleanups>(init)) {
677    enterFullExpression(ewc);
678    init = ewc->getSubExpr();
679  }
680  CodeGenFunction::RunCleanupsScope Scope(*this);
681
682  // We have to maintain the illusion that the variable is
683  // zero-initialized.  If the variable might be accessed in its
684  // initializer, zero-initialize before running the initializer, then
685  // actually perform the initialization with an assign.
686  bool accessedByInit = false;
687  if (lifetime != Qualifiers::OCL_ExplicitNone)
688    accessedByInit = (capturedByInit || isAccessedBy(D, init));
689  if (accessedByInit) {
690    LValue tempLV = lvalue;
691    // Drill down to the __block object if necessary.
692    if (capturedByInit) {
693      // We can use a simple GEP for this because it can't have been
694      // moved yet.
695      tempLV.setAddress(emitBlockByrefAddress(tempLV.getAddress(),
696                                              cast<VarDecl>(D),
697                                              /*follow*/ false));
698    }
699
700    auto ty = cast<llvm::PointerType>(tempLV.getAddress().getElementType());
701    llvm::Value *zero = llvm::ConstantPointerNull::get(ty);
702
703    // If __weak, we want to use a barrier under certain conditions.
704    if (lifetime == Qualifiers::OCL_Weak)
705      EmitARCInitWeak(tempLV.getAddress(), zero);
706
707    // Otherwise just do a simple store.
708    else
709      EmitStoreOfScalar(zero, tempLV, /* isInitialization */ true);
710  }
711
712  // Emit the initializer.
713  llvm::Value *value = nullptr;
714
715  switch (lifetime) {
716  case Qualifiers::OCL_None:
717    llvm_unreachable("present but none");
718
719  case Qualifiers::OCL_ExplicitNone:
720    value = EmitARCUnsafeUnretainedScalarExpr(init);
721    break;
722
723  case Qualifiers::OCL_Strong: {
724    value = EmitARCRetainScalarExpr(init);
725    break;
726  }
727
728  case Qualifiers::OCL_Weak: {
729    // If it's not accessed by the initializer, try to emit the
730    // initialization with a copy or move.
731    if (!accessedByInit && tryEmitARCCopyWeakInit(*this, lvalue, init)) {
732      return;
733    }
734
735    // No way to optimize a producing initializer into this.  It's not
736    // worth optimizing for, because the value will immediately
737    // disappear in the common case.
738    value = EmitScalarExpr(init);
739
740    if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
741    if (accessedByInit)
742      EmitARCStoreWeak(lvalue.getAddress(), value, /*ignored*/ true);
743    else
744      EmitARCInitWeak(lvalue.getAddress(), value);
745    return;
746  }
747
748  case Qualifiers::OCL_Autoreleasing:
749    value = EmitARCRetainAutoreleaseScalarExpr(init);
750    break;
751  }
752
753  if (capturedByInit) drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
754
755  // If the variable might have been accessed by its initializer, we
756  // might have to initialize with a barrier.  We have to do this for
757  // both __weak and __strong, but __weak got filtered out above.
758  if (accessedByInit && lifetime == Qualifiers::OCL_Strong) {
759    llvm::Value *oldValue = EmitLoadOfScalar(lvalue, init->getExprLoc());
760    EmitStoreOfScalar(value, lvalue, /* isInitialization */ true);
761    EmitARCRelease(oldValue, ARCImpreciseLifetime);
762    return;
763  }
764
765  EmitStoreOfScalar(value, lvalue, /* isInitialization */ true);
766}
767
768/// EmitScalarInit - Initialize the given lvalue with the given object.
769void CodeGenFunction::EmitScalarInit(llvm::Value *init, LValue lvalue) {
770  Qualifiers::ObjCLifetime lifetime = lvalue.getObjCLifetime();
771  if (!lifetime)
772    return EmitStoreThroughLValue(RValue::get(init), lvalue, true);
773
774  switch (lifetime) {
775  case Qualifiers::OCL_None:
776    llvm_unreachable("present but none");
777
778  case Qualifiers::OCL_ExplicitNone:
779    // nothing to do
780    break;
781
782  case Qualifiers::OCL_Strong:
783    init = EmitARCRetain(lvalue.getType(), init);
784    break;
785
786  case Qualifiers::OCL_Weak:
787    // Initialize and then skip the primitive store.
788    EmitARCInitWeak(lvalue.getAddress(), init);
789    return;
790
791  case Qualifiers::OCL_Autoreleasing:
792    init = EmitARCRetainAutorelease(lvalue.getType(), init);
793    break;
794  }
795
796  EmitStoreOfScalar(init, lvalue, /* isInitialization */ true);
797}
798
799/// canEmitInitWithFewStoresAfterMemset - Decide whether we can emit the
800/// non-zero parts of the specified initializer with equal or fewer than
801/// NumStores scalar stores.
802static bool canEmitInitWithFewStoresAfterMemset(llvm::Constant *Init,
803                                                unsigned &NumStores) {
804  // Zero and Undef never requires any extra stores.
805  if (isa<llvm::ConstantAggregateZero>(Init) ||
806      isa<llvm::ConstantPointerNull>(Init) ||
807      isa<llvm::UndefValue>(Init))
808    return true;
809  if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
810      isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
811      isa<llvm::ConstantExpr>(Init))
812    return Init->isNullValue() || NumStores--;
813
814  // See if we can emit each element.
815  if (isa<llvm::ConstantArray>(Init) || isa<llvm::ConstantStruct>(Init)) {
816    for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
817      llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
818      if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores))
819        return false;
820    }
821    return true;
822  }
823
824  if (llvm::ConstantDataSequential *CDS =
825        dyn_cast<llvm::ConstantDataSequential>(Init)) {
826    for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
827      llvm::Constant *Elt = CDS->getElementAsConstant(i);
828      if (!canEmitInitWithFewStoresAfterMemset(Elt, NumStores))
829        return false;
830    }
831    return true;
832  }
833
834  // Anything else is hard and scary.
835  return false;
836}
837
838/// emitStoresForInitAfterMemset - For inits that
839/// canEmitInitWithFewStoresAfterMemset returned true for, emit the scalar
840/// stores that would be required.
841static void emitStoresForInitAfterMemset(llvm::Constant *Init, llvm::Value *Loc,
842                                         bool isVolatile, CGBuilderTy &Builder) {
843  assert(!Init->isNullValue() && !isa<llvm::UndefValue>(Init) &&
844         "called emitStoresForInitAfterMemset for zero or undef value.");
845
846  if (isa<llvm::ConstantInt>(Init) || isa<llvm::ConstantFP>(Init) ||
847      isa<llvm::ConstantVector>(Init) || isa<llvm::BlockAddress>(Init) ||
848      isa<llvm::ConstantExpr>(Init)) {
849    Builder.CreateDefaultAlignedStore(Init, Loc, isVolatile);
850    return;
851  }
852
853  if (llvm::ConstantDataSequential *CDS =
854          dyn_cast<llvm::ConstantDataSequential>(Init)) {
855    for (unsigned i = 0, e = CDS->getNumElements(); i != e; ++i) {
856      llvm::Constant *Elt = CDS->getElementAsConstant(i);
857
858      // If necessary, get a pointer to the element and emit it.
859      if (!Elt->isNullValue() && !isa<llvm::UndefValue>(Elt))
860        emitStoresForInitAfterMemset(
861            Elt, Builder.CreateConstGEP2_32(Init->getType(), Loc, 0, i),
862            isVolatile, Builder);
863    }
864    return;
865  }
866
867  assert((isa<llvm::ConstantStruct>(Init) || isa<llvm::ConstantArray>(Init)) &&
868         "Unknown value type!");
869
870  for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) {
871    llvm::Constant *Elt = cast<llvm::Constant>(Init->getOperand(i));
872
873    // If necessary, get a pointer to the element and emit it.
874    if (!Elt->isNullValue() && !isa<llvm::UndefValue>(Elt))
875      emitStoresForInitAfterMemset(
876          Elt, Builder.CreateConstGEP2_32(Init->getType(), Loc, 0, i),
877          isVolatile, Builder);
878  }
879}
880
881/// shouldUseMemSetPlusStoresToInitialize - Decide whether we should use memset
882/// plus some stores to initialize a local variable instead of using a memcpy
883/// from a constant global.  It is beneficial to use memset if the global is all
884/// zeros, or mostly zeros and large.
885static bool shouldUseMemSetPlusStoresToInitialize(llvm::Constant *Init,
886                                                  uint64_t GlobalSize) {
887  // If a global is all zeros, always use a memset.
888  if (isa<llvm::ConstantAggregateZero>(Init)) return true;
889
890  // If a non-zero global is <= 32 bytes, always use a memcpy.  If it is large,
891  // do it if it will require 6 or fewer scalar stores.
892  // TODO: Should budget depends on the size?  Avoiding a large global warrants
893  // plopping in more stores.
894  unsigned StoreBudget = 6;
895  uint64_t SizeLimit = 32;
896
897  return GlobalSize > SizeLimit &&
898         canEmitInitWithFewStoresAfterMemset(Init, StoreBudget);
899}
900
901/// EmitAutoVarDecl - Emit code and set up an entry in LocalDeclMap for a
902/// variable declaration with auto, register, or no storage class specifier.
903/// These turn into simple stack objects, or GlobalValues depending on target.
904void CodeGenFunction::EmitAutoVarDecl(const VarDecl &D) {
905  AutoVarEmission emission = EmitAutoVarAlloca(D);
906  EmitAutoVarInit(emission);
907  EmitAutoVarCleanups(emission);
908}
909
910/// shouldEmitLifetimeMarkers - Decide whether we need emit the life-time
911/// markers.
912static bool shouldEmitLifetimeMarkers(const CodeGenOptions &CGOpts,
913                                      const LangOptions &LangOpts) {
914  // Asan uses markers for use-after-scope checks.
915  if (CGOpts.SanitizeAddressUseAfterScope)
916    return true;
917
918  // Disable lifetime markers in msan builds.
919  // FIXME: Remove this when msan works with lifetime markers.
920  if (LangOpts.Sanitize.has(SanitizerKind::Memory))
921    return false;
922
923  // For now, only in optimized builds.
924  return CGOpts.OptimizationLevel != 0;
925}
926
927/// Emit a lifetime.begin marker if some criteria are satisfied.
928/// \return a pointer to the temporary size Value if a marker was emitted, null
929/// otherwise
930llvm::Value *CodeGenFunction::EmitLifetimeStart(uint64_t Size,
931                                                llvm::Value *Addr) {
932  if (!shouldEmitLifetimeMarkers(CGM.getCodeGenOpts(), getLangOpts()))
933    return nullptr;
934
935  llvm::Value *SizeV = llvm::ConstantInt::get(Int64Ty, Size);
936  Addr = Builder.CreateBitCast(Addr, Int8PtrTy);
937  llvm::CallInst *C =
938      Builder.CreateCall(CGM.getLLVMLifetimeStartFn(), {SizeV, Addr});
939  C->setDoesNotThrow();
940  return SizeV;
941}
942
943void CodeGenFunction::EmitLifetimeEnd(llvm::Value *Size, llvm::Value *Addr) {
944  Addr = Builder.CreateBitCast(Addr, Int8PtrTy);
945  llvm::CallInst *C =
946      Builder.CreateCall(CGM.getLLVMLifetimeEndFn(), {Size, Addr});
947  C->setDoesNotThrow();
948}
949
950/// EmitAutoVarAlloca - Emit the alloca and debug information for a
951/// local variable.  Does not emit initialization or destruction.
952CodeGenFunction::AutoVarEmission
953CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) {
954  QualType Ty = D.getType();
955
956  AutoVarEmission emission(D);
957
958  bool isByRef = D.hasAttr<BlocksAttr>();
959  emission.IsByRef = isByRef;
960
961  CharUnits alignment = getContext().getDeclAlign(&D);
962
963  // If the type is variably-modified, emit all the VLA sizes for it.
964  if (Ty->isVariablyModifiedType())
965    EmitVariablyModifiedType(Ty);
966
967  Address address = Address::invalid();
968  if (Ty->isConstantSizeType()) {
969    bool NRVO = getLangOpts().ElideConstructors &&
970      D.isNRVOVariable();
971
972    // If this value is an array or struct with a statically determinable
973    // constant initializer, there are optimizations we can do.
974    //
975    // TODO: We should constant-evaluate the initializer of any variable,
976    // as long as it is initialized by a constant expression. Currently,
977    // isConstantInitializer produces wrong answers for structs with
978    // reference or bitfield members, and a few other cases, and checking
979    // for POD-ness protects us from some of these.
980    if (D.getInit() && (Ty->isArrayType() || Ty->isRecordType()) &&
981        (D.isConstexpr() ||
982         ((Ty.isPODType(getContext()) ||
983           getContext().getBaseElementType(Ty)->isObjCObjectPointerType()) &&
984          D.getInit()->isConstantInitializer(getContext(), false)))) {
985
986      // If the variable's a const type, and it's neither an NRVO
987      // candidate nor a __block variable and has no mutable members,
988      // emit it as a global instead.
989      if (CGM.getCodeGenOpts().MergeAllConstants && !NRVO && !isByRef &&
990          CGM.isTypeConstant(Ty, true)) {
991        EmitStaticVarDecl(D, llvm::GlobalValue::InternalLinkage);
992
993        // Signal this condition to later callbacks.
994        emission.Addr = Address::invalid();
995        assert(emission.wasEmittedAsGlobal());
996        return emission;
997      }
998
999      // Otherwise, tell the initialization code that we're in this case.
1000      emission.IsConstantAggregate = true;
1001    }
1002
1003    // A normal fixed sized variable becomes an alloca in the entry block,
1004    // unless it's an NRVO variable.
1005
1006    if (NRVO) {
1007      // The named return value optimization: allocate this variable in the
1008      // return slot, so that we can elide the copy when returning this
1009      // variable (C++0x [class.copy]p34).
1010      address = ReturnValue;
1011
1012      if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
1013        if (!cast<CXXRecordDecl>(RecordTy->getDecl())->hasTrivialDestructor()) {
1014          // Create a flag that is used to indicate when the NRVO was applied
1015          // to this variable. Set it to zero to indicate that NRVO was not
1016          // applied.
1017          llvm::Value *Zero = Builder.getFalse();
1018          Address NRVOFlag =
1019            CreateTempAlloca(Zero->getType(), CharUnits::One(), "nrvo");
1020          EnsureInsertPoint();
1021          Builder.CreateStore(Zero, NRVOFlag);
1022
1023          // Record the NRVO flag for this variable.
1024          NRVOFlags[&D] = NRVOFlag.getPointer();
1025          emission.NRVOFlag = NRVOFlag.getPointer();
1026        }
1027      }
1028    } else {
1029      CharUnits allocaAlignment;
1030      llvm::Type *allocaTy;
1031      if (isByRef) {
1032        auto &byrefInfo = getBlockByrefInfo(&D);
1033        allocaTy = byrefInfo.Type;
1034        allocaAlignment = byrefInfo.ByrefAlignment;
1035      } else {
1036        allocaTy = ConvertTypeForMem(Ty);
1037        allocaAlignment = alignment;
1038      }
1039
1040      // Create the alloca.  Note that we set the name separately from
1041      // building the instruction so that it's there even in no-asserts
1042      // builds.
1043      address = CreateTempAlloca(allocaTy, allocaAlignment);
1044      address.getPointer()->setName(D.getName());
1045
1046      // Don't emit lifetime markers for MSVC catch parameters. The lifetime of
1047      // the catch parameter starts in the catchpad instruction, and we can't
1048      // insert code in those basic blocks.
1049      bool IsMSCatchParam =
1050          D.isExceptionVariable() && getTarget().getCXXABI().isMicrosoft();
1051
1052      // Emit a lifetime intrinsic if meaningful.  There's no point
1053      // in doing this if we don't have a valid insertion point (?).
1054      if (HaveInsertPoint() && !IsMSCatchParam) {
1055        uint64_t size = CGM.getDataLayout().getTypeAllocSize(allocaTy);
1056        emission.SizeForLifetimeMarkers =
1057          EmitLifetimeStart(size, address.getPointer());
1058      } else {
1059        assert(!emission.useLifetimeMarkers());
1060      }
1061    }
1062  } else {
1063    EnsureInsertPoint();
1064
1065    if (!DidCallStackSave) {
1066      // Save the stack.
1067      Address Stack =
1068        CreateTempAlloca(Int8PtrTy, getPointerAlign(), "saved_stack");
1069
1070      llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::stacksave);
1071      llvm::Value *V = Builder.CreateCall(F);
1072      Builder.CreateStore(V, Stack);
1073
1074      DidCallStackSave = true;
1075
1076      // Push a cleanup block and restore the stack there.
1077      // FIXME: in general circumstances, this should be an EH cleanup.
1078      pushStackRestore(NormalCleanup, Stack);
1079    }
1080
1081    llvm::Value *elementCount;
1082    QualType elementType;
1083    std::tie(elementCount, elementType) = getVLASize(Ty);
1084
1085    llvm::Type *llvmTy = ConvertTypeForMem(elementType);
1086
1087    // Allocate memory for the array.
1088    llvm::AllocaInst *vla = Builder.CreateAlloca(llvmTy, elementCount, "vla");
1089    vla->setAlignment(alignment.getQuantity());
1090
1091    address = Address(vla, alignment);
1092  }
1093
1094  setAddrOfLocalVar(&D, address);
1095  emission.Addr = address;
1096
1097  // Emit debug info for local var declaration.
1098  if (HaveInsertPoint())
1099    if (CGDebugInfo *DI = getDebugInfo()) {
1100      if (CGM.getCodeGenOpts().getDebugInfo() >=
1101          codegenoptions::LimitedDebugInfo) {
1102        DI->setLocation(D.getLocation());
1103        DI->EmitDeclareOfAutoVariable(&D, address.getPointer(), Builder);
1104      }
1105    }
1106
1107  if (D.hasAttr<AnnotateAttr>())
1108    EmitVarAnnotations(&D, address.getPointer());
1109
1110  return emission;
1111}
1112
1113/// Determines whether the given __block variable is potentially
1114/// captured by the given expression.
1115static bool isCapturedBy(const VarDecl &var, const Expr *e) {
1116  // Skip the most common kinds of expressions that make
1117  // hierarchy-walking expensive.
1118  e = e->IgnoreParenCasts();
1119
1120  if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) {
1121    const BlockDecl *block = be->getBlockDecl();
1122    for (const auto &I : block->captures()) {
1123      if (I.getVariable() == &var)
1124        return true;
1125    }
1126
1127    // No need to walk into the subexpressions.
1128    return false;
1129  }
1130
1131  if (const StmtExpr *SE = dyn_cast<StmtExpr>(e)) {
1132    const CompoundStmt *CS = SE->getSubStmt();
1133    for (const auto *BI : CS->body())
1134      if (const auto *E = dyn_cast<Expr>(BI)) {
1135        if (isCapturedBy(var, E))
1136            return true;
1137      }
1138      else if (const auto *DS = dyn_cast<DeclStmt>(BI)) {
1139          // special case declarations
1140          for (const auto *I : DS->decls()) {
1141              if (const auto *VD = dyn_cast<VarDecl>((I))) {
1142                const Expr *Init = VD->getInit();
1143                if (Init && isCapturedBy(var, Init))
1144                  return true;
1145              }
1146          }
1147      }
1148      else
1149        // FIXME. Make safe assumption assuming arbitrary statements cause capturing.
1150        // Later, provide code to poke into statements for capture analysis.
1151        return true;
1152    return false;
1153  }
1154
1155  for (const Stmt *SubStmt : e->children())
1156    if (isCapturedBy(var, cast<Expr>(SubStmt)))
1157      return true;
1158
1159  return false;
1160}
1161
1162/// \brief Determine whether the given initializer is trivial in the sense
1163/// that it requires no code to be generated.
1164bool CodeGenFunction::isTrivialInitializer(const Expr *Init) {
1165  if (!Init)
1166    return true;
1167
1168  if (const CXXConstructExpr *Construct = dyn_cast<CXXConstructExpr>(Init))
1169    if (CXXConstructorDecl *Constructor = Construct->getConstructor())
1170      if (Constructor->isTrivial() &&
1171          Constructor->isDefaultConstructor() &&
1172          !Construct->requiresZeroInitialization())
1173        return true;
1174
1175  return false;
1176}
1177
1178void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) {
1179  assert(emission.Variable && "emission was not valid!");
1180
1181  // If this was emitted as a global constant, we're done.
1182  if (emission.wasEmittedAsGlobal()) return;
1183
1184  const VarDecl &D = *emission.Variable;
1185  auto DL = ApplyDebugLocation::CreateDefaultArtificial(*this, D.getLocation());
1186  QualType type = D.getType();
1187
1188  // If this local has an initializer, emit it now.
1189  const Expr *Init = D.getInit();
1190
1191  // If we are at an unreachable point, we don't need to emit the initializer
1192  // unless it contains a label.
1193  if (!HaveInsertPoint()) {
1194    if (!Init || !ContainsLabel(Init)) return;
1195    EnsureInsertPoint();
1196  }
1197
1198  // Initialize the structure of a __block variable.
1199  if (emission.IsByRef)
1200    emitByrefStructureInit(emission);
1201
1202  if (isTrivialInitializer(Init))
1203    return;
1204
1205  // Check whether this is a byref variable that's potentially
1206  // captured and moved by its own initializer.  If so, we'll need to
1207  // emit the initializer first, then copy into the variable.
1208  bool capturedByInit = emission.IsByRef && isCapturedBy(D, Init);
1209
1210  Address Loc =
1211    capturedByInit ? emission.Addr : emission.getObjectAddress(*this);
1212
1213  llvm::Constant *constant = nullptr;
1214  if (emission.IsConstantAggregate || D.isConstexpr()) {
1215    assert(!capturedByInit && "constant init contains a capturing block?");
1216    constant = CGM.EmitConstantInit(D, this);
1217  }
1218
1219  if (!constant) {
1220    LValue lv = MakeAddrLValue(Loc, type);
1221    lv.setNonGC(true);
1222    return EmitExprAsInit(Init, &D, lv, capturedByInit);
1223  }
1224
1225  if (!emission.IsConstantAggregate) {
1226    // For simple scalar/complex initialization, store the value directly.
1227    LValue lv = MakeAddrLValue(Loc, type);
1228    lv.setNonGC(true);
1229    return EmitStoreThroughLValue(RValue::get(constant), lv, true);
1230  }
1231
1232  // If this is a simple aggregate initialization, we can optimize it
1233  // in various ways.
1234  bool isVolatile = type.isVolatileQualified();
1235
1236  llvm::Value *SizeVal =
1237    llvm::ConstantInt::get(IntPtrTy,
1238                           getContext().getTypeSizeInChars(type).getQuantity());
1239
1240  llvm::Type *BP = Int8PtrTy;
1241  if (Loc.getType() != BP)
1242    Loc = Builder.CreateBitCast(Loc, BP);
1243
1244  // If the initializer is all or mostly zeros, codegen with memset then do
1245  // a few stores afterward.
1246  if (shouldUseMemSetPlusStoresToInitialize(constant,
1247                CGM.getDataLayout().getTypeAllocSize(constant->getType()))) {
1248    Builder.CreateMemSet(Loc, llvm::ConstantInt::get(Int8Ty, 0), SizeVal,
1249                         isVolatile);
1250    // Zero and undef don't require a stores.
1251    if (!constant->isNullValue() && !isa<llvm::UndefValue>(constant)) {
1252      Loc = Builder.CreateBitCast(Loc, constant->getType()->getPointerTo());
1253      emitStoresForInitAfterMemset(constant, Loc.getPointer(),
1254                                   isVolatile, Builder);
1255    }
1256  } else {
1257    // Otherwise, create a temporary global with the initializer then
1258    // memcpy from the global to the alloca.
1259    std::string Name = getStaticDeclName(CGM, D);
1260    llvm::GlobalVariable *GV =
1261      new llvm::GlobalVariable(CGM.getModule(), constant->getType(), true,
1262                               llvm::GlobalValue::PrivateLinkage,
1263                               constant, Name);
1264    GV->setAlignment(Loc.getAlignment().getQuantity());
1265    GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
1266
1267    Address SrcPtr = Address(GV, Loc.getAlignment());
1268    if (SrcPtr.getType() != BP)
1269      SrcPtr = Builder.CreateBitCast(SrcPtr, BP);
1270
1271    Builder.CreateMemCpy(Loc, SrcPtr, SizeVal, isVolatile);
1272  }
1273}
1274
1275/// Emit an expression as an initializer for a variable at the given
1276/// location.  The expression is not necessarily the normal
1277/// initializer for the variable, and the address is not necessarily
1278/// its normal location.
1279///
1280/// \param init the initializing expression
1281/// \param var the variable to act as if we're initializing
1282/// \param loc the address to initialize; its type is a pointer
1283///   to the LLVM mapping of the variable's type
1284/// \param alignment the alignment of the address
1285/// \param capturedByInit true if the variable is a __block variable
1286///   whose address is potentially changed by the initializer
1287void CodeGenFunction::EmitExprAsInit(const Expr *init, const ValueDecl *D,
1288                                     LValue lvalue, bool capturedByInit) {
1289  QualType type = D->getType();
1290
1291  if (type->isReferenceType()) {
1292    RValue rvalue = EmitReferenceBindingToExpr(init);
1293    if (capturedByInit)
1294      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
1295    EmitStoreThroughLValue(rvalue, lvalue, true);
1296    return;
1297  }
1298  switch (getEvaluationKind(type)) {
1299  case TEK_Scalar:
1300    EmitScalarInit(init, D, lvalue, capturedByInit);
1301    return;
1302  case TEK_Complex: {
1303    ComplexPairTy complex = EmitComplexExpr(init);
1304    if (capturedByInit)
1305      drillIntoBlockVariable(*this, lvalue, cast<VarDecl>(D));
1306    EmitStoreOfComplex(complex, lvalue, /*init*/ true);
1307    return;
1308  }
1309  case TEK_Aggregate:
1310    if (type->isAtomicType()) {
1311      EmitAtomicInit(const_cast<Expr*>(init), lvalue);
1312    } else {
1313      // TODO: how can we delay here if D is captured by its initializer?
1314      EmitAggExpr(init, AggValueSlot::forLValue(lvalue,
1315                                              AggValueSlot::IsDestructed,
1316                                         AggValueSlot::DoesNotNeedGCBarriers,
1317                                              AggValueSlot::IsNotAliased));
1318    }
1319    return;
1320  }
1321  llvm_unreachable("bad evaluation kind");
1322}
1323
1324/// Enter a destroy cleanup for the given local variable.
1325void CodeGenFunction::emitAutoVarTypeCleanup(
1326                            const CodeGenFunction::AutoVarEmission &emission,
1327                            QualType::DestructionKind dtorKind) {
1328  assert(dtorKind != QualType::DK_none);
1329
1330  // Note that for __block variables, we want to destroy the
1331  // original stack object, not the possibly forwarded object.
1332  Address addr = emission.getObjectAddress(*this);
1333
1334  const VarDecl *var = emission.Variable;
1335  QualType type = var->getType();
1336
1337  CleanupKind cleanupKind = NormalAndEHCleanup;
1338  CodeGenFunction::Destroyer *destroyer = nullptr;
1339
1340  switch (dtorKind) {
1341  case QualType::DK_none:
1342    llvm_unreachable("no cleanup for trivially-destructible variable");
1343
1344  case QualType::DK_cxx_destructor:
1345    // If there's an NRVO flag on the emission, we need a different
1346    // cleanup.
1347    if (emission.NRVOFlag) {
1348      assert(!type->isArrayType());
1349      CXXDestructorDecl *dtor = type->getAsCXXRecordDecl()->getDestructor();
1350      EHStack.pushCleanup<DestroyNRVOVariable>(cleanupKind, addr,
1351                                               dtor, emission.NRVOFlag);
1352      return;
1353    }
1354    break;
1355
1356  case QualType::DK_objc_strong_lifetime:
1357    // Suppress cleanups for pseudo-strong variables.
1358    if (var->isARCPseudoStrong()) return;
1359
1360    // Otherwise, consider whether to use an EH cleanup or not.
1361    cleanupKind = getARCCleanupKind();
1362
1363    // Use the imprecise destroyer by default.
1364    if (!var->hasAttr<ObjCPreciseLifetimeAttr>())
1365      destroyer = CodeGenFunction::destroyARCStrongImprecise;
1366    break;
1367
1368  case QualType::DK_objc_weak_lifetime:
1369    break;
1370  }
1371
1372  // If we haven't chosen a more specific destroyer, use the default.
1373  if (!destroyer) destroyer = getDestroyer(dtorKind);
1374
1375  // Use an EH cleanup in array destructors iff the destructor itself
1376  // is being pushed as an EH cleanup.
1377  bool useEHCleanup = (cleanupKind & EHCleanup);
1378  EHStack.pushCleanup<DestroyObject>(cleanupKind, addr, type, destroyer,
1379                                     useEHCleanup);
1380}
1381
1382void CodeGenFunction::EmitAutoVarCleanups(const AutoVarEmission &emission) {
1383  assert(emission.Variable && "emission was not valid!");
1384
1385  // If this was emitted as a global constant, we're done.
1386  if (emission.wasEmittedAsGlobal()) return;
1387
1388  // If we don't have an insertion point, we're done.  Sema prevents
1389  // us from jumping into any of these scopes anyway.
1390  if (!HaveInsertPoint()) return;
1391
1392  const VarDecl &D = *emission.Variable;
1393
1394  // Make sure we call @llvm.lifetime.end.  This needs to happen
1395  // *last*, so the cleanup needs to be pushed *first*.
1396  if (emission.useLifetimeMarkers())
1397    EHStack.pushCleanup<CallLifetimeEnd>(NormalEHLifetimeMarker,
1398                                         emission.getAllocatedAddress(),
1399                                         emission.getSizeForLifetimeMarkers());
1400
1401  // Check the type for a cleanup.
1402  if (QualType::DestructionKind dtorKind = D.getType().isDestructedType())
1403    emitAutoVarTypeCleanup(emission, dtorKind);
1404
1405  // In GC mode, honor objc_precise_lifetime.
1406  if (getLangOpts().getGC() != LangOptions::NonGC &&
1407      D.hasAttr<ObjCPreciseLifetimeAttr>()) {
1408    EHStack.pushCleanup<ExtendGCLifetime>(NormalCleanup, &D);
1409  }
1410
1411  // Handle the cleanup attribute.
1412  if (const CleanupAttr *CA = D.getAttr<CleanupAttr>()) {
1413    const FunctionDecl *FD = CA->getFunctionDecl();
1414
1415    llvm::Constant *F = CGM.GetAddrOfFunction(FD);
1416    assert(F && "Could not find function!");
1417
1418    const CGFunctionInfo &Info = CGM.getTypes().arrangeFunctionDeclaration(FD);
1419    EHStack.pushCleanup<CallCleanupFunction>(NormalAndEHCleanup, F, &Info, &D);
1420  }
1421
1422  // If this is a block variable, call _Block_object_destroy
1423  // (on the unforwarded address).
1424  if (emission.IsByRef)
1425    enterByrefCleanup(emission);
1426}
1427
1428CodeGenFunction::Destroyer *
1429CodeGenFunction::getDestroyer(QualType::DestructionKind kind) {
1430  switch (kind) {
1431  case QualType::DK_none: llvm_unreachable("no destroyer for trivial dtor");
1432  case QualType::DK_cxx_destructor:
1433    return destroyCXXObject;
1434  case QualType::DK_objc_strong_lifetime:
1435    return destroyARCStrongPrecise;
1436  case QualType::DK_objc_weak_lifetime:
1437    return destroyARCWeak;
1438  }
1439  llvm_unreachable("Unknown DestructionKind");
1440}
1441
1442/// pushEHDestroy - Push the standard destructor for the given type as
1443/// an EH-only cleanup.
1444void CodeGenFunction::pushEHDestroy(QualType::DestructionKind dtorKind,
1445                                    Address addr, QualType type) {
1446  assert(dtorKind && "cannot push destructor for trivial type");
1447  assert(needsEHCleanup(dtorKind));
1448
1449  pushDestroy(EHCleanup, addr, type, getDestroyer(dtorKind), true);
1450}
1451
1452/// pushDestroy - Push the standard destructor for the given type as
1453/// at least a normal cleanup.
1454void CodeGenFunction::pushDestroy(QualType::DestructionKind dtorKind,
1455                                  Address addr, QualType type) {
1456  assert(dtorKind && "cannot push destructor for trivial type");
1457
1458  CleanupKind cleanupKind = getCleanupKind(dtorKind);
1459  pushDestroy(cleanupKind, addr, type, getDestroyer(dtorKind),
1460              cleanupKind & EHCleanup);
1461}
1462
1463void CodeGenFunction::pushDestroy(CleanupKind cleanupKind, Address addr,
1464                                  QualType type, Destroyer *destroyer,
1465                                  bool useEHCleanupForArray) {
1466  pushFullExprCleanup<DestroyObject>(cleanupKind, addr, type,
1467                                     destroyer, useEHCleanupForArray);
1468}
1469
1470void CodeGenFunction::pushStackRestore(CleanupKind Kind, Address SPMem) {
1471  EHStack.pushCleanup<CallStackRestore>(Kind, SPMem);
1472}
1473
1474void CodeGenFunction::pushLifetimeExtendedDestroy(
1475    CleanupKind cleanupKind, Address addr, QualType type,
1476    Destroyer *destroyer, bool useEHCleanupForArray) {
1477  assert(!isInConditionalBranch() &&
1478         "performing lifetime extension from within conditional");
1479
1480  // Push an EH-only cleanup for the object now.
1481  // FIXME: When popping normal cleanups, we need to keep this EH cleanup
1482  // around in case a temporary's destructor throws an exception.
1483  if (cleanupKind & EHCleanup)
1484    EHStack.pushCleanup<DestroyObject>(
1485        static_cast<CleanupKind>(cleanupKind & ~NormalCleanup), addr, type,
1486        destroyer, useEHCleanupForArray);
1487
1488  // Remember that we need to push a full cleanup for the object at the
1489  // end of the full-expression.
1490  pushCleanupAfterFullExpr<DestroyObject>(
1491      cleanupKind, addr, type, destroyer, useEHCleanupForArray);
1492}
1493
1494/// emitDestroy - Immediately perform the destruction of the given
1495/// object.
1496///
1497/// \param addr - the address of the object; a type*
1498/// \param type - the type of the object; if an array type, all
1499///   objects are destroyed in reverse order
1500/// \param destroyer - the function to call to destroy individual
1501///   elements
1502/// \param useEHCleanupForArray - whether an EH cleanup should be
1503///   used when destroying array elements, in case one of the
1504///   destructions throws an exception
1505void CodeGenFunction::emitDestroy(Address addr, QualType type,
1506                                  Destroyer *destroyer,
1507                                  bool useEHCleanupForArray) {
1508  const ArrayType *arrayType = getContext().getAsArrayType(type);
1509  if (!arrayType)
1510    return destroyer(*this, addr, type);
1511
1512  llvm::Value *length = emitArrayLength(arrayType, type, addr);
1513
1514  CharUnits elementAlign =
1515    addr.getAlignment()
1516        .alignmentOfArrayElement(getContext().getTypeSizeInChars(type));
1517
1518  // Normally we have to check whether the array is zero-length.
1519  bool checkZeroLength = true;
1520
1521  // But if the array length is constant, we can suppress that.
1522  if (llvm::ConstantInt *constLength = dyn_cast<llvm::ConstantInt>(length)) {
1523    // ...and if it's constant zero, we can just skip the entire thing.
1524    if (constLength->isZero()) return;
1525    checkZeroLength = false;
1526  }
1527
1528  llvm::Value *begin = addr.getPointer();
1529  llvm::Value *end = Builder.CreateInBoundsGEP(begin, length);
1530  emitArrayDestroy(begin, end, type, elementAlign, destroyer,
1531                   checkZeroLength, useEHCleanupForArray);
1532}
1533
1534/// emitArrayDestroy - Destroys all the elements of the given array,
1535/// beginning from last to first.  The array cannot be zero-length.
1536///
1537/// \param begin - a type* denoting the first element of the array
1538/// \param end - a type* denoting one past the end of the array
1539/// \param elementType - the element type of the array
1540/// \param destroyer - the function to call to destroy elements
1541/// \param useEHCleanup - whether to push an EH cleanup to destroy
1542///   the remaining elements in case the destruction of a single
1543///   element throws
1544void CodeGenFunction::emitArrayDestroy(llvm::Value *begin,
1545                                       llvm::Value *end,
1546                                       QualType elementType,
1547                                       CharUnits elementAlign,
1548                                       Destroyer *destroyer,
1549                                       bool checkZeroLength,
1550                                       bool useEHCleanup) {
1551  assert(!elementType->isArrayType());
1552
1553  // The basic structure here is a do-while loop, because we don't
1554  // need to check for the zero-element case.
1555  llvm::BasicBlock *bodyBB = createBasicBlock("arraydestroy.body");
1556  llvm::BasicBlock *doneBB = createBasicBlock("arraydestroy.done");
1557
1558  if (checkZeroLength) {
1559    llvm::Value *isEmpty = Builder.CreateICmpEQ(begin, end,
1560                                                "arraydestroy.isempty");
1561    Builder.CreateCondBr(isEmpty, doneBB, bodyBB);
1562  }
1563
1564  // Enter the loop body, making that address the current address.
1565  llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
1566  EmitBlock(bodyBB);
1567  llvm::PHINode *elementPast =
1568    Builder.CreatePHI(begin->getType(), 2, "arraydestroy.elementPast");
1569  elementPast->addIncoming(end, entryBB);
1570
1571  // Shift the address back by one element.
1572  llvm::Value *negativeOne = llvm::ConstantInt::get(SizeTy, -1, true);
1573  llvm::Value *element = Builder.CreateInBoundsGEP(elementPast, negativeOne,
1574                                                   "arraydestroy.element");
1575
1576  if (useEHCleanup)
1577    pushRegularPartialArrayCleanup(begin, element, elementType, elementAlign,
1578                                   destroyer);
1579
1580  // Perform the actual destruction there.
1581  destroyer(*this, Address(element, elementAlign), elementType);
1582
1583  if (useEHCleanup)
1584    PopCleanupBlock();
1585
1586  // Check whether we've reached the end.
1587  llvm::Value *done = Builder.CreateICmpEQ(element, begin, "arraydestroy.done");
1588  Builder.CreateCondBr(done, doneBB, bodyBB);
1589  elementPast->addIncoming(element, Builder.GetInsertBlock());
1590
1591  // Done.
1592  EmitBlock(doneBB);
1593}
1594
1595/// Perform partial array destruction as if in an EH cleanup.  Unlike
1596/// emitArrayDestroy, the element type here may still be an array type.
1597static void emitPartialArrayDestroy(CodeGenFunction &CGF,
1598                                    llvm::Value *begin, llvm::Value *end,
1599                                    QualType type, CharUnits elementAlign,
1600                                    CodeGenFunction::Destroyer *destroyer) {
1601  // If the element type is itself an array, drill down.
1602  unsigned arrayDepth = 0;
1603  while (const ArrayType *arrayType = CGF.getContext().getAsArrayType(type)) {
1604    // VLAs don't require a GEP index to walk into.
1605    if (!isa<VariableArrayType>(arrayType))
1606      arrayDepth++;
1607    type = arrayType->getElementType();
1608  }
1609
1610  if (arrayDepth) {
1611    llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, 0);
1612
1613    SmallVector<llvm::Value*,4> gepIndices(arrayDepth+1, zero);
1614    begin = CGF.Builder.CreateInBoundsGEP(begin, gepIndices, "pad.arraybegin");
1615    end = CGF.Builder.CreateInBoundsGEP(end, gepIndices, "pad.arrayend");
1616  }
1617
1618  // Destroy the array.  We don't ever need an EH cleanup because we
1619  // assume that we're in an EH cleanup ourselves, so a throwing
1620  // destructor causes an immediate terminate.
1621  CGF.emitArrayDestroy(begin, end, type, elementAlign, destroyer,
1622                       /*checkZeroLength*/ true, /*useEHCleanup*/ false);
1623}
1624
1625namespace {
1626  /// RegularPartialArrayDestroy - a cleanup which performs a partial
1627  /// array destroy where the end pointer is regularly determined and
1628  /// does not need to be loaded from a local.
1629  class RegularPartialArrayDestroy final : public EHScopeStack::Cleanup {
1630    llvm::Value *ArrayBegin;
1631    llvm::Value *ArrayEnd;
1632    QualType ElementType;
1633    CodeGenFunction::Destroyer *Destroyer;
1634    CharUnits ElementAlign;
1635  public:
1636    RegularPartialArrayDestroy(llvm::Value *arrayBegin, llvm::Value *arrayEnd,
1637                               QualType elementType, CharUnits elementAlign,
1638                               CodeGenFunction::Destroyer *destroyer)
1639      : ArrayBegin(arrayBegin), ArrayEnd(arrayEnd),
1640        ElementType(elementType), Destroyer(destroyer),
1641        ElementAlign(elementAlign) {}
1642
1643    void Emit(CodeGenFunction &CGF, Flags flags) override {
1644      emitPartialArrayDestroy(CGF, ArrayBegin, ArrayEnd,
1645                              ElementType, ElementAlign, Destroyer);
1646    }
1647  };
1648
1649  /// IrregularPartialArrayDestroy - a cleanup which performs a
1650  /// partial array destroy where the end pointer is irregularly
1651  /// determined and must be loaded from a local.
1652  class IrregularPartialArrayDestroy final : public EHScopeStack::Cleanup {
1653    llvm::Value *ArrayBegin;
1654    Address ArrayEndPointer;
1655    QualType ElementType;
1656    CodeGenFunction::Destroyer *Destroyer;
1657    CharUnits ElementAlign;
1658  public:
1659    IrregularPartialArrayDestroy(llvm::Value *arrayBegin,
1660                                 Address arrayEndPointer,
1661                                 QualType elementType,
1662                                 CharUnits elementAlign,
1663                                 CodeGenFunction::Destroyer *destroyer)
1664      : ArrayBegin(arrayBegin), ArrayEndPointer(arrayEndPointer),
1665        ElementType(elementType), Destroyer(destroyer),
1666        ElementAlign(elementAlign) {}
1667
1668    void Emit(CodeGenFunction &CGF, Flags flags) override {
1669      llvm::Value *arrayEnd = CGF.Builder.CreateLoad(ArrayEndPointer);
1670      emitPartialArrayDestroy(CGF, ArrayBegin, arrayEnd,
1671                              ElementType, ElementAlign, Destroyer);
1672    }
1673  };
1674} // end anonymous namespace
1675
1676/// pushIrregularPartialArrayCleanup - Push an EH cleanup to destroy
1677/// already-constructed elements of the given array.  The cleanup
1678/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
1679///
1680/// \param elementType - the immediate element type of the array;
1681///   possibly still an array type
1682void CodeGenFunction::pushIrregularPartialArrayCleanup(llvm::Value *arrayBegin,
1683                                                       Address arrayEndPointer,
1684                                                       QualType elementType,
1685                                                       CharUnits elementAlign,
1686                                                       Destroyer *destroyer) {
1687  pushFullExprCleanup<IrregularPartialArrayDestroy>(EHCleanup,
1688                                                    arrayBegin, arrayEndPointer,
1689                                                    elementType, elementAlign,
1690                                                    destroyer);
1691}
1692
1693/// pushRegularPartialArrayCleanup - Push an EH cleanup to destroy
1694/// already-constructed elements of the given array.  The cleanup
1695/// may be popped with DeactivateCleanupBlock or PopCleanupBlock.
1696///
1697/// \param elementType - the immediate element type of the array;
1698///   possibly still an array type
1699void CodeGenFunction::pushRegularPartialArrayCleanup(llvm::Value *arrayBegin,
1700                                                     llvm::Value *arrayEnd,
1701                                                     QualType elementType,
1702                                                     CharUnits elementAlign,
1703                                                     Destroyer *destroyer) {
1704  pushFullExprCleanup<RegularPartialArrayDestroy>(EHCleanup,
1705                                                  arrayBegin, arrayEnd,
1706                                                  elementType, elementAlign,
1707                                                  destroyer);
1708}
1709
1710/// Lazily declare the @llvm.lifetime.start intrinsic.
1711llvm::Constant *CodeGenModule::getLLVMLifetimeStartFn() {
1712  if (LifetimeStartFn) return LifetimeStartFn;
1713  LifetimeStartFn = llvm::Intrinsic::getDeclaration(&getModule(),
1714                                            llvm::Intrinsic::lifetime_start);
1715  return LifetimeStartFn;
1716}
1717
1718/// Lazily declare the @llvm.lifetime.end intrinsic.
1719llvm::Constant *CodeGenModule::getLLVMLifetimeEndFn() {
1720  if (LifetimeEndFn) return LifetimeEndFn;
1721  LifetimeEndFn = llvm::Intrinsic::getDeclaration(&getModule(),
1722                                              llvm::Intrinsic::lifetime_end);
1723  return LifetimeEndFn;
1724}
1725
1726namespace {
1727  /// A cleanup to perform a release of an object at the end of a
1728  /// function.  This is used to balance out the incoming +1 of a
1729  /// ns_consumed argument when we can't reasonably do that just by
1730  /// not doing the initial retain for a __block argument.
1731  struct ConsumeARCParameter final : EHScopeStack::Cleanup {
1732    ConsumeARCParameter(llvm::Value *param,
1733                        ARCPreciseLifetime_t precise)
1734      : Param(param), Precise(precise) {}
1735
1736    llvm::Value *Param;
1737    ARCPreciseLifetime_t Precise;
1738
1739    void Emit(CodeGenFunction &CGF, Flags flags) override {
1740      CGF.EmitARCRelease(Param, Precise);
1741    }
1742  };
1743} // end anonymous namespace
1744
1745/// Emit an alloca (or GlobalValue depending on target)
1746/// for the specified parameter and set up LocalDeclMap.
1747void CodeGenFunction::EmitParmDecl(const VarDecl &D, ParamValue Arg,
1748                                   unsigned ArgNo) {
1749  // FIXME: Why isn't ImplicitParamDecl a ParmVarDecl?
1750  assert((isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D)) &&
1751         "Invalid argument to EmitParmDecl");
1752
1753  Arg.getAnyValue()->setName(D.getName());
1754
1755  QualType Ty = D.getType();
1756
1757  // Use better IR generation for certain implicit parameters.
1758  if (auto IPD = dyn_cast<ImplicitParamDecl>(&D)) {
1759    // The only implicit argument a block has is its literal.
1760    // We assume this is always passed directly.
1761    if (BlockInfo) {
1762      setBlockContextParameter(IPD, ArgNo, Arg.getDirectValue());
1763      return;
1764    }
1765  }
1766
1767  Address DeclPtr = Address::invalid();
1768  bool DoStore = false;
1769  bool IsScalar = hasScalarEvaluationKind(Ty);
1770  // If we already have a pointer to the argument, reuse the input pointer.
1771  if (Arg.isIndirect()) {
1772    DeclPtr = Arg.getIndirectAddress();
1773    // If we have a prettier pointer type at this point, bitcast to that.
1774    unsigned AS = DeclPtr.getType()->getAddressSpace();
1775    llvm::Type *IRTy = ConvertTypeForMem(Ty)->getPointerTo(AS);
1776    if (DeclPtr.getType() != IRTy)
1777      DeclPtr = Builder.CreateBitCast(DeclPtr, IRTy, D.getName());
1778
1779    // Push a destructor cleanup for this parameter if the ABI requires it.
1780    // Don't push a cleanup in a thunk for a method that will also emit a
1781    // cleanup.
1782    if (!IsScalar && !CurFuncIsThunk &&
1783        getTarget().getCXXABI().areArgsDestroyedLeftToRightInCallee()) {
1784      const CXXRecordDecl *RD = Ty->getAsCXXRecordDecl();
1785      if (RD && RD->hasNonTrivialDestructor())
1786        pushDestroy(QualType::DK_cxx_destructor, DeclPtr, Ty);
1787    }
1788  } else {
1789    // Otherwise, create a temporary to hold the value.
1790    DeclPtr = CreateMemTemp(Ty, getContext().getDeclAlign(&D),
1791                            D.getName() + ".addr");
1792    DoStore = true;
1793  }
1794
1795  llvm::Value *ArgVal = (DoStore ? Arg.getDirectValue() : nullptr);
1796
1797  LValue lv = MakeAddrLValue(DeclPtr, Ty);
1798  if (IsScalar) {
1799    Qualifiers qs = Ty.getQualifiers();
1800    if (Qualifiers::ObjCLifetime lt = qs.getObjCLifetime()) {
1801      // We honor __attribute__((ns_consumed)) for types with lifetime.
1802      // For __strong, it's handled by just skipping the initial retain;
1803      // otherwise we have to balance out the initial +1 with an extra
1804      // cleanup to do the release at the end of the function.
1805      bool isConsumed = D.hasAttr<NSConsumedAttr>();
1806
1807      // 'self' is always formally __strong, but if this is not an
1808      // init method then we don't want to retain it.
1809      if (D.isARCPseudoStrong()) {
1810        const ObjCMethodDecl *method = cast<ObjCMethodDecl>(CurCodeDecl);
1811        assert(&D == method->getSelfDecl());
1812        assert(lt == Qualifiers::OCL_Strong);
1813        assert(qs.hasConst());
1814        assert(method->getMethodFamily() != OMF_init);
1815        (void) method;
1816        lt = Qualifiers::OCL_ExplicitNone;
1817      }
1818
1819      if (lt == Qualifiers::OCL_Strong) {
1820        if (!isConsumed) {
1821          if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
1822            // use objc_storeStrong(&dest, value) for retaining the
1823            // object. But first, store a null into 'dest' because
1824            // objc_storeStrong attempts to release its old value.
1825            llvm::Value *Null = CGM.EmitNullConstant(D.getType());
1826            EmitStoreOfScalar(Null, lv, /* isInitialization */ true);
1827            EmitARCStoreStrongCall(lv.getAddress(), ArgVal, true);
1828            DoStore = false;
1829          }
1830          else
1831          // Don't use objc_retainBlock for block pointers, because we
1832          // don't want to Block_copy something just because we got it
1833          // as a parameter.
1834            ArgVal = EmitARCRetainNonBlock(ArgVal);
1835        }
1836      } else {
1837        // Push the cleanup for a consumed parameter.
1838        if (isConsumed) {
1839          ARCPreciseLifetime_t precise = (D.hasAttr<ObjCPreciseLifetimeAttr>()
1840                                ? ARCPreciseLifetime : ARCImpreciseLifetime);
1841          EHStack.pushCleanup<ConsumeARCParameter>(getARCCleanupKind(), ArgVal,
1842                                                   precise);
1843        }
1844
1845        if (lt == Qualifiers::OCL_Weak) {
1846          EmitARCInitWeak(DeclPtr, ArgVal);
1847          DoStore = false; // The weak init is a store, no need to do two.
1848        }
1849      }
1850
1851      // Enter the cleanup scope.
1852      EmitAutoVarWithLifetime(*this, D, DeclPtr, lt);
1853    }
1854  }
1855
1856  // Store the initial value into the alloca.
1857  if (DoStore)
1858    EmitStoreOfScalar(ArgVal, lv, /* isInitialization */ true);
1859
1860  setAddrOfLocalVar(&D, DeclPtr);
1861
1862  // Emit debug info for param declaration.
1863  if (CGDebugInfo *DI = getDebugInfo()) {
1864    if (CGM.getCodeGenOpts().getDebugInfo() >=
1865        codegenoptions::LimitedDebugInfo) {
1866      DI->EmitDeclareOfArgVariable(&D, DeclPtr.getPointer(), ArgNo, Builder);
1867    }
1868  }
1869
1870  if (D.hasAttr<AnnotateAttr>())
1871    EmitVarAnnotations(&D, DeclPtr.getPointer());
1872}
1873
1874void CodeGenModule::EmitOMPDeclareReduction(const OMPDeclareReductionDecl *D,
1875                                            CodeGenFunction *CGF) {
1876  if (!LangOpts.OpenMP || (!LangOpts.EmitAllDecls && !D->isUsed()))
1877    return;
1878  getOpenMPRuntime().emitUserDefinedReduction(CGF, D);
1879}
1880