1//===--- CGDeclCXX.cpp - Emit LLVM Code for C++ 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 dealing with code generation of C++ declarations
11//
12//===----------------------------------------------------------------------===//
13
14#include "CodeGenFunction.h"
15#include "CGCXXABI.h"
16#include "CGObjCRuntime.h"
17#include "CGOpenMPRuntime.h"
18#include "clang/Frontend/CodeGenOptions.h"
19#include "llvm/ADT/StringExtras.h"
20#include "llvm/IR/Intrinsics.h"
21#include "llvm/Support/Path.h"
22
23using namespace clang;
24using namespace CodeGen;
25
26static void EmitDeclInit(CodeGenFunction &CGF, const VarDecl &D,
27                         llvm::Constant *DeclPtr) {
28  assert(D.hasGlobalStorage() && "VarDecl must have global storage!");
29  assert(!D.getType()->isReferenceType() &&
30         "Should not call EmitDeclInit on a reference!");
31
32  ASTContext &Context = CGF.getContext();
33
34  CharUnits alignment = Context.getDeclAlign(&D);
35  QualType type = D.getType();
36  LValue lv = CGF.MakeAddrLValue(DeclPtr, type, alignment);
37
38  const Expr *Init = D.getInit();
39  switch (CGF.getEvaluationKind(type)) {
40  case TEK_Scalar: {
41    CodeGenModule &CGM = CGF.CGM;
42    if (lv.isObjCStrong())
43      CGM.getObjCRuntime().EmitObjCGlobalAssign(CGF, CGF.EmitScalarExpr(Init),
44                                                DeclPtr, D.getTLSKind());
45    else if (lv.isObjCWeak())
46      CGM.getObjCRuntime().EmitObjCWeakAssign(CGF, CGF.EmitScalarExpr(Init),
47                                              DeclPtr);
48    else
49      CGF.EmitScalarInit(Init, &D, lv, false);
50    return;
51  }
52  case TEK_Complex:
53    CGF.EmitComplexExprIntoLValue(Init, lv, /*isInit*/ true);
54    return;
55  case TEK_Aggregate:
56    CGF.EmitAggExpr(Init, AggValueSlot::forLValue(lv,AggValueSlot::IsDestructed,
57                                          AggValueSlot::DoesNotNeedGCBarriers,
58                                                  AggValueSlot::IsNotAliased));
59    return;
60  }
61  llvm_unreachable("bad evaluation kind");
62}
63
64/// Emit code to cause the destruction of the given variable with
65/// static storage duration.
66static void EmitDeclDestroy(CodeGenFunction &CGF, const VarDecl &D,
67                            llvm::Constant *addr) {
68  CodeGenModule &CGM = CGF.CGM;
69
70  // FIXME:  __attribute__((cleanup)) ?
71
72  QualType type = D.getType();
73  QualType::DestructionKind dtorKind = type.isDestructedType();
74
75  switch (dtorKind) {
76  case QualType::DK_none:
77    return;
78
79  case QualType::DK_cxx_destructor:
80    break;
81
82  case QualType::DK_objc_strong_lifetime:
83  case QualType::DK_objc_weak_lifetime:
84    // We don't care about releasing objects during process teardown.
85    assert(!D.getTLSKind() && "should have rejected this");
86    return;
87  }
88
89  llvm::Constant *function;
90  llvm::Constant *argument;
91
92  // Special-case non-array C++ destructors, where there's a function
93  // with the right signature that we can just call.
94  const CXXRecordDecl *record = nullptr;
95  if (dtorKind == QualType::DK_cxx_destructor &&
96      (record = type->getAsCXXRecordDecl())) {
97    assert(!record->hasTrivialDestructor());
98    CXXDestructorDecl *dtor = record->getDestructor();
99
100    function = CGM.getAddrOfCXXStructor(dtor, StructorType::Complete);
101    argument = llvm::ConstantExpr::getBitCast(
102        addr, CGF.getTypes().ConvertType(type)->getPointerTo());
103
104  // Otherwise, the standard logic requires a helper function.
105  } else {
106    function = CodeGenFunction(CGM)
107        .generateDestroyHelper(addr, type, CGF.getDestroyer(dtorKind),
108                               CGF.needsEHCleanup(dtorKind), &D);
109    argument = llvm::Constant::getNullValue(CGF.Int8PtrTy);
110  }
111
112  CGM.getCXXABI().registerGlobalDtor(CGF, D, function, argument);
113}
114
115/// Emit code to cause the variable at the given address to be considered as
116/// constant from this point onwards.
117static void EmitDeclInvariant(CodeGenFunction &CGF, const VarDecl &D,
118                              llvm::Constant *Addr) {
119  // Don't emit the intrinsic if we're not optimizing.
120  if (!CGF.CGM.getCodeGenOpts().OptimizationLevel)
121    return;
122
123  // Grab the llvm.invariant.start intrinsic.
124  llvm::Intrinsic::ID InvStartID = llvm::Intrinsic::invariant_start;
125  llvm::Constant *InvariantStart = CGF.CGM.getIntrinsic(InvStartID);
126
127  // Emit a call with the size in bytes of the object.
128  CharUnits WidthChars = CGF.getContext().getTypeSizeInChars(D.getType());
129  uint64_t Width = WidthChars.getQuantity();
130  llvm::Value *Args[2] = { llvm::ConstantInt::getSigned(CGF.Int64Ty, Width),
131                           llvm::ConstantExpr::getBitCast(Addr, CGF.Int8PtrTy)};
132  CGF.Builder.CreateCall(InvariantStart, Args);
133}
134
135void CodeGenFunction::EmitCXXGlobalVarDeclInit(const VarDecl &D,
136                                               llvm::Constant *DeclPtr,
137                                               bool PerformInit) {
138
139  const Expr *Init = D.getInit();
140  QualType T = D.getType();
141
142  // The address space of a static local variable (DeclPtr) may be different
143  // from the address space of the "this" argument of the constructor. In that
144  // case, we need an addrspacecast before calling the constructor.
145  //
146  // struct StructWithCtor {
147  //   __device__ StructWithCtor() {...}
148  // };
149  // __device__ void foo() {
150  //   __shared__ StructWithCtor s;
151  //   ...
152  // }
153  //
154  // For example, in the above CUDA code, the static local variable s has a
155  // "shared" address space qualifier, but the constructor of StructWithCtor
156  // expects "this" in the "generic" address space.
157  unsigned ExpectedAddrSpace = getContext().getTargetAddressSpace(T);
158  unsigned ActualAddrSpace = DeclPtr->getType()->getPointerAddressSpace();
159  if (ActualAddrSpace != ExpectedAddrSpace) {
160    llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(T);
161    llvm::PointerType *PTy = llvm::PointerType::get(LTy, ExpectedAddrSpace);
162    DeclPtr = llvm::ConstantExpr::getAddrSpaceCast(DeclPtr, PTy);
163  }
164
165  if (!T->isReferenceType()) {
166    if (getLangOpts().OpenMP && D.hasAttr<OMPThreadPrivateDeclAttr>())
167      (void)CGM.getOpenMPRuntime().emitThreadPrivateVarDefinition(
168          &D, DeclPtr, D.getAttr<OMPThreadPrivateDeclAttr>()->getLocation(),
169          PerformInit, this);
170    if (PerformInit)
171      EmitDeclInit(*this, D, DeclPtr);
172    if (CGM.isTypeConstant(D.getType(), true))
173      EmitDeclInvariant(*this, D, DeclPtr);
174    else
175      EmitDeclDestroy(*this, D, DeclPtr);
176    return;
177  }
178
179  assert(PerformInit && "cannot have constant initializer which needs "
180         "destruction for reference");
181  unsigned Alignment = getContext().getDeclAlign(&D).getQuantity();
182  RValue RV = EmitReferenceBindingToExpr(Init);
183  EmitStoreOfScalar(RV.getScalarVal(), DeclPtr, false, Alignment, T);
184}
185
186/// Create a stub function, suitable for being passed to atexit,
187/// which passes the given address to the given destructor function.
188llvm::Constant *CodeGenFunction::createAtExitStub(const VarDecl &VD,
189                                                  llvm::Constant *dtor,
190                                                  llvm::Constant *addr) {
191  // Get the destructor function type, void(*)(void).
192  llvm::FunctionType *ty = llvm::FunctionType::get(CGM.VoidTy, false);
193  SmallString<256> FnName;
194  {
195    llvm::raw_svector_ostream Out(FnName);
196    CGM.getCXXABI().getMangleContext().mangleDynamicAtExitDestructor(&VD, Out);
197  }
198  llvm::Function *fn = CGM.CreateGlobalInitOrDestructFunction(ty, FnName.str(),
199                                                              VD.getLocation());
200
201  CodeGenFunction CGF(CGM);
202
203  CGF.StartFunction(&VD, CGM.getContext().VoidTy, fn,
204                    CGM.getTypes().arrangeNullaryFunction(), FunctionArgList());
205
206  llvm::CallInst *call = CGF.Builder.CreateCall(dtor, addr);
207
208 // Make sure the call and the callee agree on calling convention.
209  if (llvm::Function *dtorFn =
210        dyn_cast<llvm::Function>(dtor->stripPointerCasts()))
211    call->setCallingConv(dtorFn->getCallingConv());
212
213  CGF.FinishFunction();
214
215  return fn;
216}
217
218/// Register a global destructor using the C atexit runtime function.
219void CodeGenFunction::registerGlobalDtorWithAtExit(const VarDecl &VD,
220                                                   llvm::Constant *dtor,
221                                                   llvm::Constant *addr) {
222  // Create a function which calls the destructor.
223  llvm::Constant *dtorStub = createAtExitStub(VD, dtor, addr);
224
225  // extern "C" int atexit(void (*f)(void));
226  llvm::FunctionType *atexitTy =
227    llvm::FunctionType::get(IntTy, dtorStub->getType(), false);
228
229  llvm::Constant *atexit =
230    CGM.CreateRuntimeFunction(atexitTy, "atexit");
231  if (llvm::Function *atexitFn = dyn_cast<llvm::Function>(atexit))
232    atexitFn->setDoesNotThrow();
233
234  EmitNounwindRuntimeCall(atexit, dtorStub);
235}
236
237void CodeGenFunction::EmitCXXGuardedInit(const VarDecl &D,
238                                         llvm::GlobalVariable *DeclPtr,
239                                         bool PerformInit) {
240  // If we've been asked to forbid guard variables, emit an error now.
241  // This diagnostic is hard-coded for Darwin's use case;  we can find
242  // better phrasing if someone else needs it.
243  if (CGM.getCodeGenOpts().ForbidGuardVariables)
244    CGM.Error(D.getLocation(),
245              "this initialization requires a guard variable, which "
246              "the kernel does not support");
247
248  CGM.getCXXABI().EmitGuardedInit(*this, D, DeclPtr, PerformInit);
249}
250
251llvm::Function *CodeGenModule::CreateGlobalInitOrDestructFunction(
252    llvm::FunctionType *FTy, const Twine &Name, SourceLocation Loc, bool TLS) {
253  llvm::Function *Fn =
254    llvm::Function::Create(FTy, llvm::GlobalValue::InternalLinkage,
255                           Name, &getModule());
256  if (!getLangOpts().AppleKext && !TLS) {
257    // Set the section if needed.
258    if (const char *Section = getTarget().getStaticInitSectionSpecifier())
259      Fn->setSection(Section);
260  }
261
262  Fn->setCallingConv(getRuntimeCC());
263
264  if (!getLangOpts().Exceptions)
265    Fn->setDoesNotThrow();
266
267  if (!isInSanitizerBlacklist(Fn, Loc)) {
268    if (getLangOpts().Sanitize.has(SanitizerKind::Address))
269      Fn->addFnAttr(llvm::Attribute::SanitizeAddress);
270    if (getLangOpts().Sanitize.has(SanitizerKind::Thread))
271      Fn->addFnAttr(llvm::Attribute::SanitizeThread);
272    if (getLangOpts().Sanitize.has(SanitizerKind::Memory))
273      Fn->addFnAttr(llvm::Attribute::SanitizeMemory);
274  }
275
276  return Fn;
277}
278
279/// Create a global pointer to a function that will initialize a global
280/// variable.  The user has requested that this pointer be emitted in a specific
281/// section.
282void CodeGenModule::EmitPointerToInitFunc(const VarDecl *D,
283                                          llvm::GlobalVariable *GV,
284                                          llvm::Function *InitFunc,
285                                          InitSegAttr *ISA) {
286  llvm::GlobalVariable *PtrArray = new llvm::GlobalVariable(
287      TheModule, InitFunc->getType(), /*isConstant=*/true,
288      llvm::GlobalValue::PrivateLinkage, InitFunc, "__cxx_init_fn_ptr");
289  PtrArray->setSection(ISA->getSection());
290  addUsedGlobal(PtrArray);
291
292  // If the GV is already in a comdat group, then we have to join it.
293  if (llvm::Comdat *C = GV->getComdat())
294    PtrArray->setComdat(C);
295}
296
297void
298CodeGenModule::EmitCXXGlobalVarDeclInitFunc(const VarDecl *D,
299                                            llvm::GlobalVariable *Addr,
300                                            bool PerformInit) {
301  // Check if we've already initialized this decl.
302  auto I = DelayedCXXInitPosition.find(D);
303  if (I != DelayedCXXInitPosition.end() && I->second == ~0U)
304    return;
305
306  llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
307  SmallString<256> FnName;
308  {
309    llvm::raw_svector_ostream Out(FnName);
310    getCXXABI().getMangleContext().mangleDynamicInitializer(D, Out);
311  }
312
313  // Create a variable initialization function.
314  llvm::Function *Fn =
315      CreateGlobalInitOrDestructFunction(FTy, FnName.str(), D->getLocation());
316
317  auto *ISA = D->getAttr<InitSegAttr>();
318  CodeGenFunction(*this).GenerateCXXGlobalVarDeclInitFunc(Fn, D, Addr,
319                                                          PerformInit);
320
321  llvm::GlobalVariable *COMDATKey =
322      supportsCOMDAT() && D->isExternallyVisible() ? Addr : nullptr;
323
324  if (D->getTLSKind()) {
325    // FIXME: Should we support init_priority for thread_local?
326    // FIXME: Ideally, initialization of instantiated thread_local static data
327    // members of class templates should not trigger initialization of other
328    // entities in the TU.
329    // FIXME: We only need to register one __cxa_thread_atexit function for the
330    // entire TU.
331    CXXThreadLocalInits.push_back(Fn);
332    CXXThreadLocalInitVars.push_back(Addr);
333  } else if (PerformInit && ISA) {
334    EmitPointerToInitFunc(D, Addr, Fn, ISA);
335  } else if (auto *IPA = D->getAttr<InitPriorityAttr>()) {
336    OrderGlobalInits Key(IPA->getPriority(), PrioritizedCXXGlobalInits.size());
337    PrioritizedCXXGlobalInits.push_back(std::make_pair(Key, Fn));
338  } else if (isTemplateInstantiation(D->getTemplateSpecializationKind())) {
339    // C++ [basic.start.init]p2:
340    //   Definitions of explicitly specialized class template static data
341    //   members have ordered initialization. Other class template static data
342    //   members (i.e., implicitly or explicitly instantiated specializations)
343    //   have unordered initialization.
344    //
345    // As a consequence, we can put them into their own llvm.global_ctors entry.
346    //
347    // If the global is externally visible, put the initializer into a COMDAT
348    // group with the global being initialized.  On most platforms, this is a
349    // minor startup time optimization.  In the MS C++ ABI, there are no guard
350    // variables, so this COMDAT key is required for correctness.
351    AddGlobalCtor(Fn, 65535, COMDATKey);
352  } else if (D->hasAttr<SelectAnyAttr>()) {
353    // SelectAny globals will be comdat-folded. Put the initializer into a
354    // COMDAT group associated with the global, so the initializers get folded
355    // too.
356    AddGlobalCtor(Fn, 65535, COMDATKey);
357  } else {
358    I = DelayedCXXInitPosition.find(D); // Re-do lookup in case of re-hash.
359    if (I == DelayedCXXInitPosition.end()) {
360      CXXGlobalInits.push_back(Fn);
361    } else if (I->second != ~0U) {
362      assert(I->second < CXXGlobalInits.size() &&
363             CXXGlobalInits[I->second] == nullptr);
364      CXXGlobalInits[I->second] = Fn;
365    }
366  }
367
368  // Remember that we already emitted the initializer for this global.
369  DelayedCXXInitPosition[D] = ~0U;
370}
371
372void CodeGenModule::EmitCXXThreadLocalInitFunc() {
373  getCXXABI().EmitThreadLocalInitFuncs(
374      *this, CXXThreadLocals, CXXThreadLocalInits, CXXThreadLocalInitVars);
375
376  CXXThreadLocalInits.clear();
377  CXXThreadLocalInitVars.clear();
378  CXXThreadLocals.clear();
379}
380
381void
382CodeGenModule::EmitCXXGlobalInitFunc() {
383  while (!CXXGlobalInits.empty() && !CXXGlobalInits.back())
384    CXXGlobalInits.pop_back();
385
386  if (CXXGlobalInits.empty() && PrioritizedCXXGlobalInits.empty())
387    return;
388
389  llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
390
391
392  // Create our global initialization function.
393  if (!PrioritizedCXXGlobalInits.empty()) {
394    SmallVector<llvm::Function *, 8> LocalCXXGlobalInits;
395    llvm::array_pod_sort(PrioritizedCXXGlobalInits.begin(),
396                         PrioritizedCXXGlobalInits.end());
397    // Iterate over "chunks" of ctors with same priority and emit each chunk
398    // into separate function. Note - everything is sorted first by priority,
399    // second - by lex order, so we emit ctor functions in proper order.
400    for (SmallVectorImpl<GlobalInitData >::iterator
401           I = PrioritizedCXXGlobalInits.begin(),
402           E = PrioritizedCXXGlobalInits.end(); I != E; ) {
403      SmallVectorImpl<GlobalInitData >::iterator
404        PrioE = std::upper_bound(I + 1, E, *I, GlobalInitPriorityCmp());
405
406      LocalCXXGlobalInits.clear();
407      unsigned Priority = I->first.priority;
408      // Compute the function suffix from priority. Prepend with zeroes to make
409      // sure the function names are also ordered as priorities.
410      std::string PrioritySuffix = llvm::utostr(Priority);
411      // Priority is always <= 65535 (enforced by sema).
412      PrioritySuffix = std::string(6-PrioritySuffix.size(), '0')+PrioritySuffix;
413      llvm::Function *Fn = CreateGlobalInitOrDestructFunction(
414          FTy, "_GLOBAL__I_" + PrioritySuffix);
415
416      for (; I < PrioE; ++I)
417        LocalCXXGlobalInits.push_back(I->second);
418
419      CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn, LocalCXXGlobalInits);
420      AddGlobalCtor(Fn, Priority);
421    }
422  }
423
424  SmallString<128> FileName;
425  SourceManager &SM = Context.getSourceManager();
426  if (const FileEntry *MainFile = SM.getFileEntryForID(SM.getMainFileID())) {
427    // Include the filename in the symbol name. Including "sub_" matches gcc and
428    // makes sure these symbols appear lexicographically behind the symbols with
429    // priority emitted above.
430    FileName = llvm::sys::path::filename(MainFile->getName());
431  } else {
432    FileName = SmallString<128>("<null>");
433  }
434
435  for (size_t i = 0; i < FileName.size(); ++i) {
436    // Replace everything that's not [a-zA-Z0-9._] with a _. This set happens
437    // to be the set of C preprocessing numbers.
438    if (!isPreprocessingNumberBody(FileName[i]))
439      FileName[i] = '_';
440  }
441
442  llvm::Function *Fn = CreateGlobalInitOrDestructFunction(
443      FTy, llvm::Twine("_GLOBAL__sub_I_", FileName));
444
445  CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn, CXXGlobalInits);
446  AddGlobalCtor(Fn);
447
448  CXXGlobalInits.clear();
449  PrioritizedCXXGlobalInits.clear();
450}
451
452void CodeGenModule::EmitCXXGlobalDtorFunc() {
453  if (CXXGlobalDtors.empty())
454    return;
455
456  llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
457
458  // Create our global destructor function.
459  llvm::Function *Fn = CreateGlobalInitOrDestructFunction(FTy, "_GLOBAL__D_a");
460
461  CodeGenFunction(*this).GenerateCXXGlobalDtorsFunc(Fn, CXXGlobalDtors);
462  AddGlobalDtor(Fn);
463}
464
465/// Emit the code necessary to initialize the given global variable.
466void CodeGenFunction::GenerateCXXGlobalVarDeclInitFunc(llvm::Function *Fn,
467                                                       const VarDecl *D,
468                                                 llvm::GlobalVariable *Addr,
469                                                       bool PerformInit) {
470  // Check if we need to emit debug info for variable initializer.
471  if (D->hasAttr<NoDebugAttr>())
472    DebugInfo = nullptr; // disable debug info indefinitely for this function
473
474  CurEHLocation = D->getLocStart();
475
476  StartFunction(GlobalDecl(D), getContext().VoidTy, Fn,
477                getTypes().arrangeNullaryFunction(),
478                FunctionArgList(), D->getLocation(),
479                D->getInit()->getExprLoc());
480
481  // Use guarded initialization if the global variable is weak. This
482  // occurs for, e.g., instantiated static data members and
483  // definitions explicitly marked weak.
484  if (Addr->hasWeakLinkage() || Addr->hasLinkOnceLinkage()) {
485    EmitCXXGuardedInit(*D, Addr, PerformInit);
486  } else {
487    EmitCXXGlobalVarDeclInit(*D, Addr, PerformInit);
488  }
489
490  FinishFunction();
491}
492
493void
494CodeGenFunction::GenerateCXXGlobalInitFunc(llvm::Function *Fn,
495                                           ArrayRef<llvm::Function *> Decls,
496                                           llvm::GlobalVariable *Guard) {
497  {
498    auto NL = ApplyDebugLocation::CreateEmpty(*this);
499    StartFunction(GlobalDecl(), getContext().VoidTy, Fn,
500                  getTypes().arrangeNullaryFunction(), FunctionArgList());
501    // Emit an artificial location for this function.
502    auto AL = ApplyDebugLocation::CreateArtificial(*this);
503
504    llvm::BasicBlock *ExitBlock = nullptr;
505    if (Guard) {
506      // If we have a guard variable, check whether we've already performed
507      // these initializations. This happens for TLS initialization functions.
508      llvm::Value *GuardVal = Builder.CreateLoad(Guard);
509      llvm::Value *Uninit = Builder.CreateIsNull(GuardVal,
510                                                 "guard.uninitialized");
511      // Mark as initialized before initializing anything else. If the
512      // initializers use previously-initialized thread_local vars, that's
513      // probably supposed to be OK, but the standard doesn't say.
514      Builder.CreateStore(llvm::ConstantInt::get(GuardVal->getType(),1), Guard);
515      llvm::BasicBlock *InitBlock = createBasicBlock("init");
516      ExitBlock = createBasicBlock("exit");
517      Builder.CreateCondBr(Uninit, InitBlock, ExitBlock);
518      EmitBlock(InitBlock);
519    }
520
521    RunCleanupsScope Scope(*this);
522
523    // When building in Objective-C++ ARC mode, create an autorelease pool
524    // around the global initializers.
525    if (getLangOpts().ObjCAutoRefCount && getLangOpts().CPlusPlus) {
526      llvm::Value *token = EmitObjCAutoreleasePoolPush();
527      EmitObjCAutoreleasePoolCleanup(token);
528    }
529
530    for (unsigned i = 0, e = Decls.size(); i != e; ++i)
531      if (Decls[i])
532        EmitRuntimeCall(Decls[i]);
533
534    Scope.ForceCleanup();
535
536    if (ExitBlock) {
537      Builder.CreateBr(ExitBlock);
538      EmitBlock(ExitBlock);
539    }
540  }
541
542  FinishFunction();
543}
544
545void CodeGenFunction::GenerateCXXGlobalDtorsFunc(llvm::Function *Fn,
546                  const std::vector<std::pair<llvm::WeakVH, llvm::Constant*> >
547                                                &DtorsAndObjects) {
548  {
549    auto NL = ApplyDebugLocation::CreateEmpty(*this);
550    StartFunction(GlobalDecl(), getContext().VoidTy, Fn,
551                  getTypes().arrangeNullaryFunction(), FunctionArgList());
552    // Emit an artificial location for this function.
553    auto AL = ApplyDebugLocation::CreateArtificial(*this);
554
555    // Emit the dtors, in reverse order from construction.
556    for (unsigned i = 0, e = DtorsAndObjects.size(); i != e; ++i) {
557      llvm::Value *Callee = DtorsAndObjects[e - i - 1].first;
558      llvm::CallInst *CI = Builder.CreateCall(Callee,
559                                          DtorsAndObjects[e - i - 1].second);
560      // Make sure the call and the callee agree on calling convention.
561      if (llvm::Function *F = dyn_cast<llvm::Function>(Callee))
562        CI->setCallingConv(F->getCallingConv());
563    }
564  }
565
566  FinishFunction();
567}
568
569/// generateDestroyHelper - Generates a helper function which, when
570/// invoked, destroys the given object.
571llvm::Function *CodeGenFunction::generateDestroyHelper(
572    llvm::Constant *addr, QualType type, Destroyer *destroyer,
573    bool useEHCleanupForArray, const VarDecl *VD) {
574  FunctionArgList args;
575  ImplicitParamDecl dst(getContext(), nullptr, SourceLocation(), nullptr,
576                        getContext().VoidPtrTy);
577  args.push_back(&dst);
578
579  const CGFunctionInfo &FI = CGM.getTypes().arrangeFreeFunctionDeclaration(
580      getContext().VoidTy, args, FunctionType::ExtInfo(), /*variadic=*/false);
581  llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(FI);
582  llvm::Function *fn = CGM.CreateGlobalInitOrDestructFunction(
583      FTy, "__cxx_global_array_dtor", VD->getLocation());
584
585  CurEHLocation = VD->getLocStart();
586
587  StartFunction(VD, getContext().VoidTy, fn, FI, args);
588
589  emitDestroy(addr, type, destroyer, useEHCleanupForArray);
590
591  FinishFunction();
592
593  return fn;
594}
595