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, if they have the right signature.
90  // Under some ABIs, destructors return this instead of void, and cannot be
91  // passed directly to __cxa_atexit if the target does not allow this mismatch.
92  const CXXRecordDecl *Record = type->getAsCXXRecordDecl();
93  bool CanRegisterDestructor =
94      Record && (!CGM.getCXXABI().HasThisReturn(
95                     GlobalDecl(Record->getDestructor(), Dtor_Complete)) ||
96                 CGM.getCXXABI().canCallMismatchedFunctionType());
97  // If __cxa_atexit is disabled via a flag, a different helper function is
98  // generated elsewhere which uses atexit instead, and it takes the destructor
99  // directly.
100  bool UsingExternalHelper = !CGM.getCodeGenOpts().CXAAtExit;
101  if (Record && (CanRegisterDestructor || UsingExternalHelper)) {
102    assert(!Record->hasTrivialDestructor());
103    CXXDestructorDecl *dtor = Record->getDestructor();
104
105    function = CGM.getAddrOfCXXStructor(dtor, StructorType::Complete);
106    argument = llvm::ConstantExpr::getBitCast(
107        addr.getPointer(), CGF.getTypes().ConvertType(type)->getPointerTo());
108
109  // Otherwise, the standard logic requires a helper function.
110  } else {
111    function = CodeGenFunction(CGM)
112        .generateDestroyHelper(addr, type, CGF.getDestroyer(dtorKind),
113                               CGF.needsEHCleanup(dtorKind), &D);
114    argument = llvm::Constant::getNullValue(CGF.Int8PtrTy);
115  }
116
117  CGM.getCXXABI().registerGlobalDtor(CGF, D, function, argument);
118}
119
120/// Emit code to cause the variable at the given address to be considered as
121/// constant from this point onwards.
122static void EmitDeclInvariant(CodeGenFunction &CGF, const VarDecl &D,
123                              llvm::Constant *Addr) {
124  // Don't emit the intrinsic if we're not optimizing.
125  if (!CGF.CGM.getCodeGenOpts().OptimizationLevel)
126    return;
127
128  // Grab the llvm.invariant.start intrinsic.
129  llvm::Intrinsic::ID InvStartID = llvm::Intrinsic::invariant_start;
130  llvm::Constant *InvariantStart = CGF.CGM.getIntrinsic(InvStartID);
131
132  // Emit a call with the size in bytes of the object.
133  CharUnits WidthChars = CGF.getContext().getTypeSizeInChars(D.getType());
134  uint64_t Width = WidthChars.getQuantity();
135  llvm::Value *Args[2] = { llvm::ConstantInt::getSigned(CGF.Int64Ty, Width),
136                           llvm::ConstantExpr::getBitCast(Addr, CGF.Int8PtrTy)};
137  CGF.Builder.CreateCall(InvariantStart, Args);
138}
139
140void CodeGenFunction::EmitCXXGlobalVarDeclInit(const VarDecl &D,
141                                               llvm::Constant *DeclPtr,
142                                               bool PerformInit) {
143
144  const Expr *Init = D.getInit();
145  QualType T = D.getType();
146
147  // The address space of a static local variable (DeclPtr) may be different
148  // from the address space of the "this" argument of the constructor. In that
149  // case, we need an addrspacecast before calling the constructor.
150  //
151  // struct StructWithCtor {
152  //   __device__ StructWithCtor() {...}
153  // };
154  // __device__ void foo() {
155  //   __shared__ StructWithCtor s;
156  //   ...
157  // }
158  //
159  // For example, in the above CUDA code, the static local variable s has a
160  // "shared" address space qualifier, but the constructor of StructWithCtor
161  // expects "this" in the "generic" address space.
162  unsigned ExpectedAddrSpace = getContext().getTargetAddressSpace(T);
163  unsigned ActualAddrSpace = DeclPtr->getType()->getPointerAddressSpace();
164  if (ActualAddrSpace != ExpectedAddrSpace) {
165    llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(T);
166    llvm::PointerType *PTy = llvm::PointerType::get(LTy, ExpectedAddrSpace);
167    DeclPtr = llvm::ConstantExpr::getAddrSpaceCast(DeclPtr, PTy);
168  }
169
170  ConstantAddress DeclAddr(DeclPtr, getContext().getDeclAlign(&D));
171
172  if (!T->isReferenceType()) {
173    if (getLangOpts().OpenMP && D.hasAttr<OMPThreadPrivateDeclAttr>())
174      (void)CGM.getOpenMPRuntime().emitThreadPrivateVarDefinition(
175          &D, DeclAddr, D.getAttr<OMPThreadPrivateDeclAttr>()->getLocation(),
176          PerformInit, this);
177    if (PerformInit)
178      EmitDeclInit(*this, D, DeclAddr);
179    if (CGM.isTypeConstant(D.getType(), true))
180      EmitDeclInvariant(*this, D, DeclPtr);
181    else
182      EmitDeclDestroy(*this, D, DeclAddr);
183    return;
184  }
185
186  assert(PerformInit && "cannot have constant initializer which needs "
187         "destruction for reference");
188  RValue RV = EmitReferenceBindingToExpr(Init);
189  EmitStoreOfScalar(RV.getScalarVal(), DeclAddr, false, T);
190}
191
192/// Create a stub function, suitable for being passed to atexit,
193/// which passes the given address to the given destructor function.
194llvm::Constant *CodeGenFunction::createAtExitStub(const VarDecl &VD,
195                                                  llvm::Constant *dtor,
196                                                  llvm::Constant *addr) {
197  // Get the destructor function type, void(*)(void).
198  llvm::FunctionType *ty = llvm::FunctionType::get(CGM.VoidTy, false);
199  SmallString<256> FnName;
200  {
201    llvm::raw_svector_ostream Out(FnName);
202    CGM.getCXXABI().getMangleContext().mangleDynamicAtExitDestructor(&VD, Out);
203  }
204
205  const CGFunctionInfo &FI = CGM.getTypes().arrangeNullaryFunction();
206  llvm::Function *fn = CGM.CreateGlobalInitOrDestructFunction(ty, FnName.str(),
207                                                              FI,
208                                                              VD.getLocation());
209
210  CodeGenFunction CGF(CGM);
211
212  CGF.StartFunction(&VD, CGM.getContext().VoidTy, fn, FI, FunctionArgList());
213
214  llvm::CallInst *call = CGF.Builder.CreateCall(dtor, addr);
215
216 // Make sure the call and the callee agree on calling convention.
217  if (llvm::Function *dtorFn =
218        dyn_cast<llvm::Function>(dtor->stripPointerCasts()))
219    call->setCallingConv(dtorFn->getCallingConv());
220
221  CGF.FinishFunction();
222
223  return fn;
224}
225
226/// Register a global destructor using the C atexit runtime function.
227void CodeGenFunction::registerGlobalDtorWithAtExit(const VarDecl &VD,
228                                                   llvm::Constant *dtor,
229                                                   llvm::Constant *addr) {
230  // Create a function which calls the destructor.
231  llvm::Constant *dtorStub = createAtExitStub(VD, dtor, addr);
232
233  // extern "C" int atexit(void (*f)(void));
234  llvm::FunctionType *atexitTy =
235    llvm::FunctionType::get(IntTy, dtorStub->getType(), false);
236
237  llvm::Constant *atexit =
238    CGM.CreateRuntimeFunction(atexitTy, "atexit");
239  if (llvm::Function *atexitFn = dyn_cast<llvm::Function>(atexit))
240    atexitFn->setDoesNotThrow();
241
242  EmitNounwindRuntimeCall(atexit, dtorStub);
243}
244
245void CodeGenFunction::EmitCXXGuardedInit(const VarDecl &D,
246                                         llvm::GlobalVariable *DeclPtr,
247                                         bool PerformInit) {
248  // If we've been asked to forbid guard variables, emit an error now.
249  // This diagnostic is hard-coded for Darwin's use case;  we can find
250  // better phrasing if someone else needs it.
251  if (CGM.getCodeGenOpts().ForbidGuardVariables)
252    CGM.Error(D.getLocation(),
253              "this initialization requires a guard variable, which "
254              "the kernel does not support");
255
256  CGM.getCXXABI().EmitGuardedInit(*this, D, DeclPtr, PerformInit);
257}
258
259llvm::Function *CodeGenModule::CreateGlobalInitOrDestructFunction(
260    llvm::FunctionType *FTy, const Twine &Name, const CGFunctionInfo &FI,
261    SourceLocation Loc, bool TLS) {
262  llvm::Function *Fn =
263    llvm::Function::Create(FTy, llvm::GlobalValue::InternalLinkage,
264                           Name, &getModule());
265  if (!getLangOpts().AppleKext && !TLS) {
266    // Set the section if needed.
267    if (const char *Section = getTarget().getStaticInitSectionSpecifier())
268      Fn->setSection(Section);
269  }
270
271  SetInternalFunctionAttributes(nullptr, Fn, FI);
272
273  Fn->setCallingConv(getRuntimeCC());
274
275  if (!getLangOpts().Exceptions)
276    Fn->setDoesNotThrow();
277
278  if (!isInSanitizerBlacklist(Fn, Loc)) {
279    if (getLangOpts().Sanitize.hasOneOf(SanitizerKind::Address |
280                                        SanitizerKind::KernelAddress))
281      Fn->addFnAttr(llvm::Attribute::SanitizeAddress);
282    if (getLangOpts().Sanitize.has(SanitizerKind::Thread))
283      Fn->addFnAttr(llvm::Attribute::SanitizeThread);
284    if (getLangOpts().Sanitize.has(SanitizerKind::Memory))
285      Fn->addFnAttr(llvm::Attribute::SanitizeMemory);
286    if (getLangOpts().Sanitize.has(SanitizerKind::SafeStack))
287      Fn->addFnAttr(llvm::Attribute::SafeStack);
288  }
289
290  return Fn;
291}
292
293/// Create a global pointer to a function that will initialize a global
294/// variable.  The user has requested that this pointer be emitted in a specific
295/// section.
296void CodeGenModule::EmitPointerToInitFunc(const VarDecl *D,
297                                          llvm::GlobalVariable *GV,
298                                          llvm::Function *InitFunc,
299                                          InitSegAttr *ISA) {
300  llvm::GlobalVariable *PtrArray = new llvm::GlobalVariable(
301      TheModule, InitFunc->getType(), /*isConstant=*/true,
302      llvm::GlobalValue::PrivateLinkage, InitFunc, "__cxx_init_fn_ptr");
303  PtrArray->setSection(ISA->getSection());
304  addUsedGlobal(PtrArray);
305
306  // If the GV is already in a comdat group, then we have to join it.
307  if (llvm::Comdat *C = GV->getComdat())
308    PtrArray->setComdat(C);
309}
310
311void
312CodeGenModule::EmitCXXGlobalVarDeclInitFunc(const VarDecl *D,
313                                            llvm::GlobalVariable *Addr,
314                                            bool PerformInit) {
315
316  // According to E.2.3.1 in CUDA-7.5 Programming guide: __device__,
317  // __constant__ and __shared__ variables defined in namespace scope,
318  // that are of class type, cannot have a non-empty constructor. All
319  // the checks have been done in Sema by now. Whatever initializers
320  // are allowed are empty and we just need to ignore them here.
321  if (getLangOpts().CUDA && getLangOpts().CUDAIsDevice &&
322      (D->hasAttr<CUDADeviceAttr>() || D->hasAttr<CUDAConstantAttr>() ||
323       D->hasAttr<CUDASharedAttr>()))
324    return;
325
326  // Check if we've already initialized this decl.
327  auto I = DelayedCXXInitPosition.find(D);
328  if (I != DelayedCXXInitPosition.end() && I->second == ~0U)
329    return;
330
331  llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
332  SmallString<256> FnName;
333  {
334    llvm::raw_svector_ostream Out(FnName);
335    getCXXABI().getMangleContext().mangleDynamicInitializer(D, Out);
336  }
337
338  // Create a variable initialization function.
339  llvm::Function *Fn =
340      CreateGlobalInitOrDestructFunction(FTy, FnName.str(),
341                                         getTypes().arrangeNullaryFunction(),
342                                         D->getLocation());
343
344  auto *ISA = D->getAttr<InitSegAttr>();
345  CodeGenFunction(*this).GenerateCXXGlobalVarDeclInitFunc(Fn, D, Addr,
346                                                          PerformInit);
347
348  llvm::GlobalVariable *COMDATKey =
349      supportsCOMDAT() && D->isExternallyVisible() ? Addr : nullptr;
350
351  if (D->getTLSKind()) {
352    // FIXME: Should we support init_priority for thread_local?
353    // FIXME: Ideally, initialization of instantiated thread_local static data
354    // members of class templates should not trigger initialization of other
355    // entities in the TU.
356    // FIXME: We only need to register one __cxa_thread_atexit function for the
357    // entire TU.
358    CXXThreadLocalInits.push_back(Fn);
359    CXXThreadLocalInitVars.push_back(D);
360  } else if (PerformInit && ISA) {
361    EmitPointerToInitFunc(D, Addr, Fn, ISA);
362  } else if (auto *IPA = D->getAttr<InitPriorityAttr>()) {
363    OrderGlobalInits Key(IPA->getPriority(), PrioritizedCXXGlobalInits.size());
364    PrioritizedCXXGlobalInits.push_back(std::make_pair(Key, Fn));
365  } else if (isTemplateInstantiation(D->getTemplateSpecializationKind())) {
366    // C++ [basic.start.init]p2:
367    //   Definitions of explicitly specialized class template static data
368    //   members have ordered initialization. Other class template static data
369    //   members (i.e., implicitly or explicitly instantiated specializations)
370    //   have unordered initialization.
371    //
372    // As a consequence, we can put them into their own llvm.global_ctors entry.
373    //
374    // If the global is externally visible, put the initializer into a COMDAT
375    // group with the global being initialized.  On most platforms, this is a
376    // minor startup time optimization.  In the MS C++ ABI, there are no guard
377    // variables, so this COMDAT key is required for correctness.
378    AddGlobalCtor(Fn, 65535, COMDATKey);
379  } else if (D->hasAttr<SelectAnyAttr>()) {
380    // SelectAny globals will be comdat-folded. Put the initializer into a
381    // COMDAT group associated with the global, so the initializers get folded
382    // too.
383    AddGlobalCtor(Fn, 65535, COMDATKey);
384  } else {
385    I = DelayedCXXInitPosition.find(D); // Re-do lookup in case of re-hash.
386    if (I == DelayedCXXInitPosition.end()) {
387      CXXGlobalInits.push_back(Fn);
388    } else if (I->second != ~0U) {
389      assert(I->second < CXXGlobalInits.size() &&
390             CXXGlobalInits[I->second] == nullptr);
391      CXXGlobalInits[I->second] = Fn;
392    }
393  }
394
395  // Remember that we already emitted the initializer for this global.
396  DelayedCXXInitPosition[D] = ~0U;
397}
398
399void CodeGenModule::EmitCXXThreadLocalInitFunc() {
400  getCXXABI().EmitThreadLocalInitFuncs(
401      *this, CXXThreadLocals, CXXThreadLocalInits, CXXThreadLocalInitVars);
402
403  CXXThreadLocalInits.clear();
404  CXXThreadLocalInitVars.clear();
405  CXXThreadLocals.clear();
406}
407
408void
409CodeGenModule::EmitCXXGlobalInitFunc() {
410  while (!CXXGlobalInits.empty() && !CXXGlobalInits.back())
411    CXXGlobalInits.pop_back();
412
413  if (CXXGlobalInits.empty() && PrioritizedCXXGlobalInits.empty())
414    return;
415
416  llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
417  const CGFunctionInfo &FI = getTypes().arrangeNullaryFunction();
418
419  // Create our global initialization function.
420  if (!PrioritizedCXXGlobalInits.empty()) {
421    SmallVector<llvm::Function *, 8> LocalCXXGlobalInits;
422    llvm::array_pod_sort(PrioritizedCXXGlobalInits.begin(),
423                         PrioritizedCXXGlobalInits.end());
424    // Iterate over "chunks" of ctors with same priority and emit each chunk
425    // into separate function. Note - everything is sorted first by priority,
426    // second - by lex order, so we emit ctor functions in proper order.
427    for (SmallVectorImpl<GlobalInitData >::iterator
428           I = PrioritizedCXXGlobalInits.begin(),
429           E = PrioritizedCXXGlobalInits.end(); I != E; ) {
430      SmallVectorImpl<GlobalInitData >::iterator
431        PrioE = std::upper_bound(I + 1, E, *I, GlobalInitPriorityCmp());
432
433      LocalCXXGlobalInits.clear();
434      unsigned Priority = I->first.priority;
435      // Compute the function suffix from priority. Prepend with zeroes to make
436      // sure the function names are also ordered as priorities.
437      std::string PrioritySuffix = llvm::utostr(Priority);
438      // Priority is always <= 65535 (enforced by sema).
439      PrioritySuffix = std::string(6-PrioritySuffix.size(), '0')+PrioritySuffix;
440      llvm::Function *Fn = CreateGlobalInitOrDestructFunction(
441          FTy, "_GLOBAL__I_" + PrioritySuffix, FI);
442
443      for (; I < PrioE; ++I)
444        LocalCXXGlobalInits.push_back(I->second);
445
446      CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn, LocalCXXGlobalInits);
447      AddGlobalCtor(Fn, Priority);
448    }
449    PrioritizedCXXGlobalInits.clear();
450  }
451
452  SmallString<128> FileName;
453  SourceManager &SM = Context.getSourceManager();
454  if (const FileEntry *MainFile = SM.getFileEntryForID(SM.getMainFileID())) {
455    // Include the filename in the symbol name. Including "sub_" matches gcc and
456    // makes sure these symbols appear lexicographically behind the symbols with
457    // priority emitted above.
458    FileName = llvm::sys::path::filename(MainFile->getName());
459  } else {
460    FileName = "<null>";
461  }
462
463  for (size_t i = 0; i < FileName.size(); ++i) {
464    // Replace everything that's not [a-zA-Z0-9._] with a _. This set happens
465    // to be the set of C preprocessing numbers.
466    if (!isPreprocessingNumberBody(FileName[i]))
467      FileName[i] = '_';
468  }
469
470  llvm::Function *Fn = CreateGlobalInitOrDestructFunction(
471      FTy, llvm::Twine("_GLOBAL__sub_I_", FileName), FI);
472
473  CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn, CXXGlobalInits);
474  AddGlobalCtor(Fn);
475
476  CXXGlobalInits.clear();
477}
478
479void CodeGenModule::EmitCXXGlobalDtorFunc() {
480  if (CXXGlobalDtors.empty())
481    return;
482
483  llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
484
485  // Create our global destructor function.
486  const CGFunctionInfo &FI = getTypes().arrangeNullaryFunction();
487  llvm::Function *Fn =
488      CreateGlobalInitOrDestructFunction(FTy, "_GLOBAL__D_a", FI);
489
490  CodeGenFunction(*this).GenerateCXXGlobalDtorsFunc(Fn, CXXGlobalDtors);
491  AddGlobalDtor(Fn);
492}
493
494/// Emit the code necessary to initialize the given global variable.
495void CodeGenFunction::GenerateCXXGlobalVarDeclInitFunc(llvm::Function *Fn,
496                                                       const VarDecl *D,
497                                                 llvm::GlobalVariable *Addr,
498                                                       bool PerformInit) {
499  // Check if we need to emit debug info for variable initializer.
500  if (D->hasAttr<NoDebugAttr>())
501    DebugInfo = nullptr; // disable debug info indefinitely for this function
502
503  CurEHLocation = D->getLocStart();
504
505  StartFunction(GlobalDecl(D), getContext().VoidTy, Fn,
506                getTypes().arrangeNullaryFunction(),
507                FunctionArgList(), D->getLocation(),
508                D->getInit()->getExprLoc());
509
510  // Use guarded initialization if the global variable is weak. This
511  // occurs for, e.g., instantiated static data members and
512  // definitions explicitly marked weak.
513  if (Addr->hasWeakLinkage() || Addr->hasLinkOnceLinkage()) {
514    EmitCXXGuardedInit(*D, Addr, PerformInit);
515  } else {
516    EmitCXXGlobalVarDeclInit(*D, Addr, PerformInit);
517  }
518
519  FinishFunction();
520}
521
522void
523CodeGenFunction::GenerateCXXGlobalInitFunc(llvm::Function *Fn,
524                                           ArrayRef<llvm::Function *> Decls,
525                                           Address Guard) {
526  {
527    auto NL = ApplyDebugLocation::CreateEmpty(*this);
528    StartFunction(GlobalDecl(), getContext().VoidTy, Fn,
529                  getTypes().arrangeNullaryFunction(), FunctionArgList());
530    // Emit an artificial location for this function.
531    auto AL = ApplyDebugLocation::CreateArtificial(*this);
532
533    llvm::BasicBlock *ExitBlock = nullptr;
534    if (Guard.isValid()) {
535      // If we have a guard variable, check whether we've already performed
536      // these initializations. This happens for TLS initialization functions.
537      llvm::Value *GuardVal = Builder.CreateLoad(Guard);
538      llvm::Value *Uninit = Builder.CreateIsNull(GuardVal,
539                                                 "guard.uninitialized");
540      llvm::BasicBlock *InitBlock = createBasicBlock("init");
541      ExitBlock = createBasicBlock("exit");
542      Builder.CreateCondBr(Uninit, InitBlock, ExitBlock);
543      EmitBlock(InitBlock);
544      // Mark as initialized before initializing anything else. If the
545      // initializers use previously-initialized thread_local vars, that's
546      // probably supposed to be OK, but the standard doesn't say.
547      Builder.CreateStore(llvm::ConstantInt::get(GuardVal->getType(),1), Guard);
548    }
549
550    RunCleanupsScope Scope(*this);
551
552    // When building in Objective-C++ ARC mode, create an autorelease pool
553    // around the global initializers.
554    if (getLangOpts().ObjCAutoRefCount && getLangOpts().CPlusPlus) {
555      llvm::Value *token = EmitObjCAutoreleasePoolPush();
556      EmitObjCAutoreleasePoolCleanup(token);
557    }
558
559    for (unsigned i = 0, e = Decls.size(); i != e; ++i)
560      if (Decls[i])
561        EmitRuntimeCall(Decls[i]);
562
563    Scope.ForceCleanup();
564
565    if (ExitBlock) {
566      Builder.CreateBr(ExitBlock);
567      EmitBlock(ExitBlock);
568    }
569  }
570
571  FinishFunction();
572}
573
574void CodeGenFunction::GenerateCXXGlobalDtorsFunc(llvm::Function *Fn,
575                  const std::vector<std::pair<llvm::WeakVH, llvm::Constant*> >
576                                                &DtorsAndObjects) {
577  {
578    auto NL = ApplyDebugLocation::CreateEmpty(*this);
579    StartFunction(GlobalDecl(), getContext().VoidTy, Fn,
580                  getTypes().arrangeNullaryFunction(), FunctionArgList());
581    // Emit an artificial location for this function.
582    auto AL = ApplyDebugLocation::CreateArtificial(*this);
583
584    // Emit the dtors, in reverse order from construction.
585    for (unsigned i = 0, e = DtorsAndObjects.size(); i != e; ++i) {
586      llvm::Value *Callee = DtorsAndObjects[e - i - 1].first;
587      llvm::CallInst *CI = Builder.CreateCall(Callee,
588                                          DtorsAndObjects[e - i - 1].second);
589      // Make sure the call and the callee agree on calling convention.
590      if (llvm::Function *F = dyn_cast<llvm::Function>(Callee))
591        CI->setCallingConv(F->getCallingConv());
592    }
593  }
594
595  FinishFunction();
596}
597
598/// generateDestroyHelper - Generates a helper function which, when
599/// invoked, destroys the given object.  The address of the object
600/// should be in global memory.
601llvm::Function *CodeGenFunction::generateDestroyHelper(
602    Address addr, QualType type, Destroyer *destroyer,
603    bool useEHCleanupForArray, const VarDecl *VD) {
604  FunctionArgList args;
605  ImplicitParamDecl dst(getContext(), nullptr, SourceLocation(), nullptr,
606                        getContext().VoidPtrTy);
607  args.push_back(&dst);
608
609  const CGFunctionInfo &FI =
610    CGM.getTypes().arrangeBuiltinFunctionDeclaration(getContext().VoidTy, args);
611  llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(FI);
612  llvm::Function *fn = CGM.CreateGlobalInitOrDestructFunction(
613      FTy, "__cxx_global_array_dtor", FI, VD->getLocation());
614
615  CurEHLocation = VD->getLocStart();
616
617  StartFunction(VD, getContext().VoidTy, fn, FI, args);
618
619  emitDestroy(addr, type, destroyer, useEHCleanupForArray);
620
621  FinishFunction();
622
623  return fn;
624}
625