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                         ConstantAddress 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  QualType type = D.getType();
33  LValue lv = CGF.MakeAddrLValue(DeclPtr, type);
34
35  const Expr *Init = D.getInit();
36  switch (CGF.getEvaluationKind(type)) {
37  case TEK_Scalar: {
38    CodeGenModule &CGM = CGF.CGM;
39    if (lv.isObjCStrong())
40      CGM.getObjCRuntime().EmitObjCGlobalAssign(CGF, CGF.EmitScalarExpr(Init),
41                                                DeclPtr, D.getTLSKind());
42    else if (lv.isObjCWeak())
43      CGM.getObjCRuntime().EmitObjCWeakAssign(CGF, CGF.EmitScalarExpr(Init),
44                                              DeclPtr);
45    else
46      CGF.EmitScalarInit(Init, &D, lv, false);
47    return;
48  }
49  case TEK_Complex:
50    CGF.EmitComplexExprIntoLValue(Init, lv, /*isInit*/ true);
51    return;
52  case TEK_Aggregate:
53    CGF.EmitAggExpr(Init, AggValueSlot::forLValue(lv,AggValueSlot::IsDestructed,
54                                          AggValueSlot::DoesNotNeedGCBarriers,
55                                                  AggValueSlot::IsNotAliased));
56    return;
57  }
58  llvm_unreachable("bad evaluation kind");
59}
60
61/// Emit code to cause the destruction of the given variable with
62/// static storage duration.
63static void EmitDeclDestroy(CodeGenFunction &CGF, const VarDecl &D,
64                            ConstantAddress addr) {
65  CodeGenModule &CGM = CGF.CGM;
66
67  // FIXME:  __attribute__((cleanup)) ?
68
69  QualType type = D.getType();
70  QualType::DestructionKind dtorKind = type.isDestructedType();
71
72  switch (dtorKind) {
73  case QualType::DK_none:
74    return;
75
76  case QualType::DK_cxx_destructor:
77    break;
78
79  case QualType::DK_objc_strong_lifetime:
80  case QualType::DK_objc_weak_lifetime:
81    // We don't care about releasing objects during process teardown.
82    assert(!D.getTLSKind() && "should have rejected this");
83    return;
84  }
85
86  llvm::Constant *function;
87  llvm::Constant *argument;
88
89  // Special-case non-array C++ destructors, where there's a function
90  // with the right signature that we can just call.
91  const CXXRecordDecl *record = nullptr;
92  if (dtorKind == QualType::DK_cxx_destructor &&
93      (record = type->getAsCXXRecordDecl())) {
94    assert(!record->hasTrivialDestructor());
95    CXXDestructorDecl *dtor = record->getDestructor();
96
97    function = CGM.getAddrOfCXXStructor(dtor, StructorType::Complete);
98    argument = llvm::ConstantExpr::getBitCast(
99        addr.getPointer(), CGF.getTypes().ConvertType(type)->getPointerTo());
100
101  // Otherwise, the standard logic requires a helper function.
102  } else {
103    function = CodeGenFunction(CGM)
104        .generateDestroyHelper(addr, type, CGF.getDestroyer(dtorKind),
105                               CGF.needsEHCleanup(dtorKind), &D);
106    argument = llvm::Constant::getNullValue(CGF.Int8PtrTy);
107  }
108
109  CGM.getCXXABI().registerGlobalDtor(CGF, D, function, argument);
110}
111
112/// Emit code to cause the variable at the given address to be considered as
113/// constant from this point onwards.
114static void EmitDeclInvariant(CodeGenFunction &CGF, const VarDecl &D,
115                              llvm::Constant *Addr) {
116  // Don't emit the intrinsic if we're not optimizing.
117  if (!CGF.CGM.getCodeGenOpts().OptimizationLevel)
118    return;
119
120  // Grab the llvm.invariant.start intrinsic.
121  llvm::Intrinsic::ID InvStartID = llvm::Intrinsic::invariant_start;
122  llvm::Constant *InvariantStart = CGF.CGM.getIntrinsic(InvStartID);
123
124  // Emit a call with the size in bytes of the object.
125  CharUnits WidthChars = CGF.getContext().getTypeSizeInChars(D.getType());
126  uint64_t Width = WidthChars.getQuantity();
127  llvm::Value *Args[2] = { llvm::ConstantInt::getSigned(CGF.Int64Ty, Width),
128                           llvm::ConstantExpr::getBitCast(Addr, CGF.Int8PtrTy)};
129  CGF.Builder.CreateCall(InvariantStart, Args);
130}
131
132void CodeGenFunction::EmitCXXGlobalVarDeclInit(const VarDecl &D,
133                                               llvm::Constant *DeclPtr,
134                                               bool PerformInit) {
135
136  const Expr *Init = D.getInit();
137  QualType T = D.getType();
138
139  // The address space of a static local variable (DeclPtr) may be different
140  // from the address space of the "this" argument of the constructor. In that
141  // case, we need an addrspacecast before calling the constructor.
142  //
143  // struct StructWithCtor {
144  //   __device__ StructWithCtor() {...}
145  // };
146  // __device__ void foo() {
147  //   __shared__ StructWithCtor s;
148  //   ...
149  // }
150  //
151  // For example, in the above CUDA code, the static local variable s has a
152  // "shared" address space qualifier, but the constructor of StructWithCtor
153  // expects "this" in the "generic" address space.
154  unsigned ExpectedAddrSpace = getContext().getTargetAddressSpace(T);
155  unsigned ActualAddrSpace = DeclPtr->getType()->getPointerAddressSpace();
156  if (ActualAddrSpace != ExpectedAddrSpace) {
157    llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(T);
158    llvm::PointerType *PTy = llvm::PointerType::get(LTy, ExpectedAddrSpace);
159    DeclPtr = llvm::ConstantExpr::getAddrSpaceCast(DeclPtr, PTy);
160  }
161
162  ConstantAddress DeclAddr(DeclPtr, getContext().getDeclAlign(&D));
163
164  if (!T->isReferenceType()) {
165    if (getLangOpts().OpenMP && D.hasAttr<OMPThreadPrivateDeclAttr>())
166      (void)CGM.getOpenMPRuntime().emitThreadPrivateVarDefinition(
167          &D, DeclAddr, D.getAttr<OMPThreadPrivateDeclAttr>()->getLocation(),
168          PerformInit, this);
169    if (PerformInit)
170      EmitDeclInit(*this, D, DeclAddr);
171    if (CGM.isTypeConstant(D.getType(), true))
172      EmitDeclInvariant(*this, D, DeclPtr);
173    else
174      EmitDeclDestroy(*this, D, DeclAddr);
175    return;
176  }
177
178  assert(PerformInit && "cannot have constant initializer which needs "
179         "destruction for reference");
180  RValue RV = EmitReferenceBindingToExpr(Init);
181  EmitStoreOfScalar(RV.getScalarVal(), DeclAddr, false, T);
182}
183
184/// Create a stub function, suitable for being passed to atexit,
185/// which passes the given address to the given destructor function.
186llvm::Constant *CodeGenFunction::createAtExitStub(const VarDecl &VD,
187                                                  llvm::Constant *dtor,
188                                                  llvm::Constant *addr) {
189  // Get the destructor function type, void(*)(void).
190  llvm::FunctionType *ty = llvm::FunctionType::get(CGM.VoidTy, false);
191  SmallString<256> FnName;
192  {
193    llvm::raw_svector_ostream Out(FnName);
194    CGM.getCXXABI().getMangleContext().mangleDynamicAtExitDestructor(&VD, Out);
195  }
196
197  const CGFunctionInfo &FI = CGM.getTypes().arrangeNullaryFunction();
198  llvm::Function *fn = CGM.CreateGlobalInitOrDestructFunction(ty, FnName.str(),
199                                                              FI,
200                                                              VD.getLocation());
201
202  CodeGenFunction CGF(CGM);
203
204  CGF.StartFunction(&VD, CGM.getContext().VoidTy, fn, FI, 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, const CGFunctionInfo &FI,
253    SourceLocation Loc, bool TLS) {
254  llvm::Function *Fn =
255    llvm::Function::Create(FTy, llvm::GlobalValue::InternalLinkage,
256                           Name, &getModule());
257  if (!getLangOpts().AppleKext && !TLS) {
258    // Set the section if needed.
259    if (const char *Section = getTarget().getStaticInitSectionSpecifier())
260      Fn->setSection(Section);
261  }
262
263  SetInternalFunctionAttributes(nullptr, Fn, FI);
264
265  Fn->setCallingConv(getRuntimeCC());
266
267  if (!getLangOpts().Exceptions)
268    Fn->setDoesNotThrow();
269
270  if (!isInSanitizerBlacklist(Fn, Loc)) {
271    if (getLangOpts().Sanitize.hasOneOf(SanitizerKind::Address |
272                                        SanitizerKind::KernelAddress))
273      Fn->addFnAttr(llvm::Attribute::SanitizeAddress);
274    if (getLangOpts().Sanitize.has(SanitizerKind::Thread))
275      Fn->addFnAttr(llvm::Attribute::SanitizeThread);
276    if (getLangOpts().Sanitize.has(SanitizerKind::Memory))
277      Fn->addFnAttr(llvm::Attribute::SanitizeMemory);
278    if (getLangOpts().Sanitize.has(SanitizerKind::SafeStack))
279      Fn->addFnAttr(llvm::Attribute::SafeStack);
280  }
281
282  return Fn;
283}
284
285/// Create a global pointer to a function that will initialize a global
286/// variable.  The user has requested that this pointer be emitted in a specific
287/// section.
288void CodeGenModule::EmitPointerToInitFunc(const VarDecl *D,
289                                          llvm::GlobalVariable *GV,
290                                          llvm::Function *InitFunc,
291                                          InitSegAttr *ISA) {
292  llvm::GlobalVariable *PtrArray = new llvm::GlobalVariable(
293      TheModule, InitFunc->getType(), /*isConstant=*/true,
294      llvm::GlobalValue::PrivateLinkage, InitFunc, "__cxx_init_fn_ptr");
295  PtrArray->setSection(ISA->getSection());
296  addUsedGlobal(PtrArray);
297
298  // If the GV is already in a comdat group, then we have to join it.
299  if (llvm::Comdat *C = GV->getComdat())
300    PtrArray->setComdat(C);
301}
302
303void
304CodeGenModule::EmitCXXGlobalVarDeclInitFunc(const VarDecl *D,
305                                            llvm::GlobalVariable *Addr,
306                                            bool PerformInit) {
307  // Check if we've already initialized this decl.
308  auto I = DelayedCXXInitPosition.find(D);
309  if (I != DelayedCXXInitPosition.end() && I->second == ~0U)
310    return;
311
312  llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
313  SmallString<256> FnName;
314  {
315    llvm::raw_svector_ostream Out(FnName);
316    getCXXABI().getMangleContext().mangleDynamicInitializer(D, Out);
317  }
318
319  // Create a variable initialization function.
320  llvm::Function *Fn =
321      CreateGlobalInitOrDestructFunction(FTy, FnName.str(),
322                                         getTypes().arrangeNullaryFunction(),
323                                         D->getLocation());
324
325  auto *ISA = D->getAttr<InitSegAttr>();
326  CodeGenFunction(*this).GenerateCXXGlobalVarDeclInitFunc(Fn, D, Addr,
327                                                          PerformInit);
328
329  llvm::GlobalVariable *COMDATKey =
330      supportsCOMDAT() && D->isExternallyVisible() ? Addr : nullptr;
331
332  if (D->getTLSKind()) {
333    // FIXME: Should we support init_priority for thread_local?
334    // FIXME: Ideally, initialization of instantiated thread_local static data
335    // members of class templates should not trigger initialization of other
336    // entities in the TU.
337    // FIXME: We only need to register one __cxa_thread_atexit function for the
338    // entire TU.
339    CXXThreadLocalInits.push_back(Fn);
340    CXXThreadLocalInitVars.push_back(D);
341  } else if (PerformInit && ISA) {
342    EmitPointerToInitFunc(D, Addr, Fn, ISA);
343  } else if (auto *IPA = D->getAttr<InitPriorityAttr>()) {
344    OrderGlobalInits Key(IPA->getPriority(), PrioritizedCXXGlobalInits.size());
345    PrioritizedCXXGlobalInits.push_back(std::make_pair(Key, Fn));
346  } else if (isTemplateInstantiation(D->getTemplateSpecializationKind())) {
347    // C++ [basic.start.init]p2:
348    //   Definitions of explicitly specialized class template static data
349    //   members have ordered initialization. Other class template static data
350    //   members (i.e., implicitly or explicitly instantiated specializations)
351    //   have unordered initialization.
352    //
353    // As a consequence, we can put them into their own llvm.global_ctors entry.
354    //
355    // If the global is externally visible, put the initializer into a COMDAT
356    // group with the global being initialized.  On most platforms, this is a
357    // minor startup time optimization.  In the MS C++ ABI, there are no guard
358    // variables, so this COMDAT key is required for correctness.
359    AddGlobalCtor(Fn, 65535, COMDATKey);
360  } else if (D->hasAttr<SelectAnyAttr>()) {
361    // SelectAny globals will be comdat-folded. Put the initializer into a
362    // COMDAT group associated with the global, so the initializers get folded
363    // too.
364    AddGlobalCtor(Fn, 65535, COMDATKey);
365  } else {
366    I = DelayedCXXInitPosition.find(D); // Re-do lookup in case of re-hash.
367    if (I == DelayedCXXInitPosition.end()) {
368      CXXGlobalInits.push_back(Fn);
369    } else if (I->second != ~0U) {
370      assert(I->second < CXXGlobalInits.size() &&
371             CXXGlobalInits[I->second] == nullptr);
372      CXXGlobalInits[I->second] = Fn;
373    }
374  }
375
376  // Remember that we already emitted the initializer for this global.
377  DelayedCXXInitPosition[D] = ~0U;
378}
379
380void CodeGenModule::EmitCXXThreadLocalInitFunc() {
381  getCXXABI().EmitThreadLocalInitFuncs(
382      *this, CXXThreadLocals, CXXThreadLocalInits, CXXThreadLocalInitVars);
383
384  CXXThreadLocalInits.clear();
385  CXXThreadLocalInitVars.clear();
386  CXXThreadLocals.clear();
387}
388
389void
390CodeGenModule::EmitCXXGlobalInitFunc() {
391  while (!CXXGlobalInits.empty() && !CXXGlobalInits.back())
392    CXXGlobalInits.pop_back();
393
394  if (CXXGlobalInits.empty() && PrioritizedCXXGlobalInits.empty())
395    return;
396
397  llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
398  const CGFunctionInfo &FI = getTypes().arrangeNullaryFunction();
399
400  // Create our global initialization function.
401  if (!PrioritizedCXXGlobalInits.empty()) {
402    SmallVector<llvm::Function *, 8> LocalCXXGlobalInits;
403    llvm::array_pod_sort(PrioritizedCXXGlobalInits.begin(),
404                         PrioritizedCXXGlobalInits.end());
405    // Iterate over "chunks" of ctors with same priority and emit each chunk
406    // into separate function. Note - everything is sorted first by priority,
407    // second - by lex order, so we emit ctor functions in proper order.
408    for (SmallVectorImpl<GlobalInitData >::iterator
409           I = PrioritizedCXXGlobalInits.begin(),
410           E = PrioritizedCXXGlobalInits.end(); I != E; ) {
411      SmallVectorImpl<GlobalInitData >::iterator
412        PrioE = std::upper_bound(I + 1, E, *I, GlobalInitPriorityCmp());
413
414      LocalCXXGlobalInits.clear();
415      unsigned Priority = I->first.priority;
416      // Compute the function suffix from priority. Prepend with zeroes to make
417      // sure the function names are also ordered as priorities.
418      std::string PrioritySuffix = llvm::utostr(Priority);
419      // Priority is always <= 65535 (enforced by sema).
420      PrioritySuffix = std::string(6-PrioritySuffix.size(), '0')+PrioritySuffix;
421      llvm::Function *Fn = CreateGlobalInitOrDestructFunction(
422          FTy, "_GLOBAL__I_" + PrioritySuffix, FI);
423
424      for (; I < PrioE; ++I)
425        LocalCXXGlobalInits.push_back(I->second);
426
427      CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn, LocalCXXGlobalInits);
428      AddGlobalCtor(Fn, Priority);
429    }
430    PrioritizedCXXGlobalInits.clear();
431  }
432
433  SmallString<128> FileName;
434  SourceManager &SM = Context.getSourceManager();
435  if (const FileEntry *MainFile = SM.getFileEntryForID(SM.getMainFileID())) {
436    // Include the filename in the symbol name. Including "sub_" matches gcc and
437    // makes sure these symbols appear lexicographically behind the symbols with
438    // priority emitted above.
439    FileName = llvm::sys::path::filename(MainFile->getName());
440  } else {
441    FileName = "<null>";
442  }
443
444  for (size_t i = 0; i < FileName.size(); ++i) {
445    // Replace everything that's not [a-zA-Z0-9._] with a _. This set happens
446    // to be the set of C preprocessing numbers.
447    if (!isPreprocessingNumberBody(FileName[i]))
448      FileName[i] = '_';
449  }
450
451  llvm::Function *Fn = CreateGlobalInitOrDestructFunction(
452      FTy, llvm::Twine("_GLOBAL__sub_I_", FileName), FI);
453
454  CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn, CXXGlobalInits);
455  AddGlobalCtor(Fn);
456
457  CXXGlobalInits.clear();
458}
459
460void CodeGenModule::EmitCXXGlobalDtorFunc() {
461  if (CXXGlobalDtors.empty())
462    return;
463
464  llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
465
466  // Create our global destructor function.
467  const CGFunctionInfo &FI = getTypes().arrangeNullaryFunction();
468  llvm::Function *Fn =
469      CreateGlobalInitOrDestructFunction(FTy, "_GLOBAL__D_a", FI);
470
471  CodeGenFunction(*this).GenerateCXXGlobalDtorsFunc(Fn, CXXGlobalDtors);
472  AddGlobalDtor(Fn);
473}
474
475/// Emit the code necessary to initialize the given global variable.
476void CodeGenFunction::GenerateCXXGlobalVarDeclInitFunc(llvm::Function *Fn,
477                                                       const VarDecl *D,
478                                                 llvm::GlobalVariable *Addr,
479                                                       bool PerformInit) {
480  // Check if we need to emit debug info for variable initializer.
481  if (D->hasAttr<NoDebugAttr>())
482    DebugInfo = nullptr; // disable debug info indefinitely for this function
483
484  CurEHLocation = D->getLocStart();
485
486  StartFunction(GlobalDecl(D), getContext().VoidTy, Fn,
487                getTypes().arrangeNullaryFunction(),
488                FunctionArgList(), D->getLocation(),
489                D->getInit()->getExprLoc());
490
491  // Use guarded initialization if the global variable is weak. This
492  // occurs for, e.g., instantiated static data members and
493  // definitions explicitly marked weak.
494  if (Addr->hasWeakLinkage() || Addr->hasLinkOnceLinkage()) {
495    EmitCXXGuardedInit(*D, Addr, PerformInit);
496  } else {
497    EmitCXXGlobalVarDeclInit(*D, Addr, PerformInit);
498  }
499
500  FinishFunction();
501}
502
503void
504CodeGenFunction::GenerateCXXGlobalInitFunc(llvm::Function *Fn,
505                                           ArrayRef<llvm::Function *> Decls,
506                                           Address Guard) {
507  {
508    auto NL = ApplyDebugLocation::CreateEmpty(*this);
509    StartFunction(GlobalDecl(), getContext().VoidTy, Fn,
510                  getTypes().arrangeNullaryFunction(), FunctionArgList());
511    // Emit an artificial location for this function.
512    auto AL = ApplyDebugLocation::CreateArtificial(*this);
513
514    llvm::BasicBlock *ExitBlock = nullptr;
515    if (Guard.isValid()) {
516      // If we have a guard variable, check whether we've already performed
517      // these initializations. This happens for TLS initialization functions.
518      llvm::Value *GuardVal = Builder.CreateLoad(Guard);
519      llvm::Value *Uninit = Builder.CreateIsNull(GuardVal,
520                                                 "guard.uninitialized");
521      llvm::BasicBlock *InitBlock = createBasicBlock("init");
522      ExitBlock = createBasicBlock("exit");
523      Builder.CreateCondBr(Uninit, InitBlock, ExitBlock);
524      EmitBlock(InitBlock);
525      // Mark as initialized before initializing anything else. If the
526      // initializers use previously-initialized thread_local vars, that's
527      // probably supposed to be OK, but the standard doesn't say.
528      Builder.CreateStore(llvm::ConstantInt::get(GuardVal->getType(),1), Guard);
529    }
530
531    RunCleanupsScope Scope(*this);
532
533    // When building in Objective-C++ ARC mode, create an autorelease pool
534    // around the global initializers.
535    if (getLangOpts().ObjCAutoRefCount && getLangOpts().CPlusPlus) {
536      llvm::Value *token = EmitObjCAutoreleasePoolPush();
537      EmitObjCAutoreleasePoolCleanup(token);
538    }
539
540    for (unsigned i = 0, e = Decls.size(); i != e; ++i)
541      if (Decls[i])
542        EmitRuntimeCall(Decls[i]);
543
544    Scope.ForceCleanup();
545
546    if (ExitBlock) {
547      Builder.CreateBr(ExitBlock);
548      EmitBlock(ExitBlock);
549    }
550  }
551
552  FinishFunction();
553}
554
555void CodeGenFunction::GenerateCXXGlobalDtorsFunc(llvm::Function *Fn,
556                  const std::vector<std::pair<llvm::WeakVH, llvm::Constant*> >
557                                                &DtorsAndObjects) {
558  {
559    auto NL = ApplyDebugLocation::CreateEmpty(*this);
560    StartFunction(GlobalDecl(), getContext().VoidTy, Fn,
561                  getTypes().arrangeNullaryFunction(), FunctionArgList());
562    // Emit an artificial location for this function.
563    auto AL = ApplyDebugLocation::CreateArtificial(*this);
564
565    // Emit the dtors, in reverse order from construction.
566    for (unsigned i = 0, e = DtorsAndObjects.size(); i != e; ++i) {
567      llvm::Value *Callee = DtorsAndObjects[e - i - 1].first;
568      llvm::CallInst *CI = Builder.CreateCall(Callee,
569                                          DtorsAndObjects[e - i - 1].second);
570      // Make sure the call and the callee agree on calling convention.
571      if (llvm::Function *F = dyn_cast<llvm::Function>(Callee))
572        CI->setCallingConv(F->getCallingConv());
573    }
574  }
575
576  FinishFunction();
577}
578
579/// generateDestroyHelper - Generates a helper function which, when
580/// invoked, destroys the given object.  The address of the object
581/// should be in global memory.
582llvm::Function *CodeGenFunction::generateDestroyHelper(
583    Address addr, QualType type, Destroyer *destroyer,
584    bool useEHCleanupForArray, const VarDecl *VD) {
585  FunctionArgList args;
586  ImplicitParamDecl dst(getContext(), nullptr, SourceLocation(), nullptr,
587                        getContext().VoidPtrTy);
588  args.push_back(&dst);
589
590  const CGFunctionInfo &FI = CGM.getTypes().arrangeFreeFunctionDeclaration(
591      getContext().VoidTy, args, FunctionType::ExtInfo(), /*variadic=*/false);
592  llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(FI);
593  llvm::Function *fn = CGM.CreateGlobalInitOrDestructFunction(
594      FTy, "__cxx_global_array_dtor", FI, VD->getLocation());
595
596  CurEHLocation = VD->getLocStart();
597
598  StartFunction(VD, getContext().VoidTy, fn, FI, args);
599
600  emitDestroy(addr, type, destroyer, useEHCleanupForArray);
601
602  FinishFunction();
603
604  return fn;
605}
606