xref: /freebsd/contrib/llvm-project/clang/lib/CodeGen/CGDeclCXX.cpp (revision ba3c1f5972d7b90feb6e6da47905ff2757e0fe57)
1 //===--- CGDeclCXX.cpp - Emit LLVM Code for C++ declarations --------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This contains code dealing with code generation of C++ declarations
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "CGCXXABI.h"
14 #include "CGHLSLRuntime.h"
15 #include "CGObjCRuntime.h"
16 #include "CGOpenMPRuntime.h"
17 #include "CodeGenFunction.h"
18 #include "TargetInfo.h"
19 #include "clang/AST/Attr.h"
20 #include "clang/Basic/LangOptions.h"
21 #include "llvm/ADT/StringExtras.h"
22 #include "llvm/IR/Intrinsics.h"
23 #include "llvm/IR/MDBuilder.h"
24 #include "llvm/Support/Path.h"
25 
26 using namespace clang;
27 using namespace CodeGen;
28 
29 static void EmitDeclInit(CodeGenFunction &CGF, const VarDecl &D,
30                          ConstantAddress DeclPtr) {
31   assert(
32       (D.hasGlobalStorage() ||
33        (D.hasLocalStorage() && CGF.getContext().getLangOpts().OpenCLCPlusPlus)) &&
34       "VarDecl must have global or local (in the case of OpenCL) storage!");
35   assert(!D.getType()->isReferenceType() &&
36          "Should not call EmitDeclInit on a reference!");
37 
38   QualType type = D.getType();
39   LValue lv = CGF.MakeAddrLValue(DeclPtr, type);
40 
41   const Expr *Init = D.getInit();
42   switch (CGF.getEvaluationKind(type)) {
43   case TEK_Scalar: {
44     CodeGenModule &CGM = CGF.CGM;
45     if (lv.isObjCStrong())
46       CGM.getObjCRuntime().EmitObjCGlobalAssign(CGF, CGF.EmitScalarExpr(Init),
47                                                 DeclPtr, D.getTLSKind());
48     else if (lv.isObjCWeak())
49       CGM.getObjCRuntime().EmitObjCWeakAssign(CGF, CGF.EmitScalarExpr(Init),
50                                               DeclPtr);
51     else
52       CGF.EmitScalarInit(Init, &D, lv, false);
53     return;
54   }
55   case TEK_Complex:
56     CGF.EmitComplexExprIntoLValue(Init, lv, /*isInit*/ true);
57     return;
58   case TEK_Aggregate:
59     CGF.EmitAggExpr(Init,
60                     AggValueSlot::forLValue(lv, CGF, AggValueSlot::IsDestructed,
61                                             AggValueSlot::DoesNotNeedGCBarriers,
62                                             AggValueSlot::IsNotAliased,
63                                             AggValueSlot::DoesNotOverlap));
64     return;
65   }
66   llvm_unreachable("bad evaluation kind");
67 }
68 
69 /// Emit code to cause the destruction of the given variable with
70 /// static storage duration.
71 static void EmitDeclDestroy(CodeGenFunction &CGF, const VarDecl &D,
72                             ConstantAddress Addr) {
73   // Honor __attribute__((no_destroy)) and bail instead of attempting
74   // to emit a reference to a possibly nonexistent destructor, which
75   // in turn can cause a crash. This will result in a global constructor
76   // that isn't balanced out by a destructor call as intended by the
77   // attribute. This also checks for -fno-c++-static-destructors and
78   // bails even if the attribute is not present.
79   QualType::DestructionKind DtorKind = D.needsDestruction(CGF.getContext());
80 
81   // FIXME:  __attribute__((cleanup)) ?
82 
83   switch (DtorKind) {
84   case QualType::DK_none:
85     return;
86 
87   case QualType::DK_cxx_destructor:
88     break;
89 
90   case QualType::DK_objc_strong_lifetime:
91   case QualType::DK_objc_weak_lifetime:
92   case QualType::DK_nontrivial_c_struct:
93     // We don't care about releasing objects during process teardown.
94     assert(!D.getTLSKind() && "should have rejected this");
95     return;
96   }
97 
98   llvm::FunctionCallee Func;
99   llvm::Constant *Argument;
100 
101   CodeGenModule &CGM = CGF.CGM;
102   QualType Type = D.getType();
103 
104   // Special-case non-array C++ destructors, if they have the right signature.
105   // Under some ABIs, destructors return this instead of void, and cannot be
106   // passed directly to __cxa_atexit if the target does not allow this
107   // mismatch.
108   const CXXRecordDecl *Record = Type->getAsCXXRecordDecl();
109   bool CanRegisterDestructor =
110       Record && (!CGM.getCXXABI().HasThisReturn(
111                      GlobalDecl(Record->getDestructor(), Dtor_Complete)) ||
112                  CGM.getCXXABI().canCallMismatchedFunctionType());
113   // If __cxa_atexit is disabled via a flag, a different helper function is
114   // generated elsewhere which uses atexit instead, and it takes the destructor
115   // directly.
116   bool UsingExternalHelper = !CGM.getCodeGenOpts().CXAAtExit;
117   if (Record && (CanRegisterDestructor || UsingExternalHelper)) {
118     assert(!Record->hasTrivialDestructor());
119     CXXDestructorDecl *Dtor = Record->getDestructor();
120 
121     Func = CGM.getAddrAndTypeOfCXXStructor(GlobalDecl(Dtor, Dtor_Complete));
122     if (CGF.getContext().getLangOpts().OpenCL) {
123       auto DestAS =
124           CGM.getTargetCodeGenInfo().getAddrSpaceOfCxaAtexitPtrParam();
125       auto DestTy = CGF.getTypes().ConvertType(Type)->getPointerTo(
126           CGM.getContext().getTargetAddressSpace(DestAS));
127       auto SrcAS = D.getType().getQualifiers().getAddressSpace();
128       if (DestAS == SrcAS)
129         Argument = llvm::ConstantExpr::getBitCast(Addr.getPointer(), DestTy);
130       else
131         // FIXME: On addr space mismatch we are passing NULL. The generation
132         // of the global destructor function should be adjusted accordingly.
133         Argument = llvm::ConstantPointerNull::get(DestTy);
134     } else {
135       Argument = llvm::ConstantExpr::getBitCast(
136           Addr.getPointer(), CGF.getTypes().ConvertType(Type)->getPointerTo());
137     }
138   // Otherwise, the standard logic requires a helper function.
139   } else {
140     Addr = Addr.getElementBitCast(CGF.ConvertTypeForMem(Type));
141     Func = CodeGenFunction(CGM)
142            .generateDestroyHelper(Addr, Type, CGF.getDestroyer(DtorKind),
143                                   CGF.needsEHCleanup(DtorKind), &D);
144     Argument = llvm::Constant::getNullValue(CGF.Int8PtrTy);
145   }
146 
147   CGM.getCXXABI().registerGlobalDtor(CGF, D, Func, Argument);
148 }
149 
150 /// Emit code to cause the variable at the given address to be considered as
151 /// constant from this point onwards.
152 static void EmitDeclInvariant(CodeGenFunction &CGF, const VarDecl &D,
153                               llvm::Constant *Addr) {
154   return CGF.EmitInvariantStart(
155       Addr, CGF.getContext().getTypeSizeInChars(D.getType()));
156 }
157 
158 void CodeGenFunction::EmitInvariantStart(llvm::Constant *Addr, CharUnits Size) {
159   // Do not emit the intrinsic if we're not optimizing.
160   if (!CGM.getCodeGenOpts().OptimizationLevel)
161     return;
162 
163   // Grab the llvm.invariant.start intrinsic.
164   llvm::Intrinsic::ID InvStartID = llvm::Intrinsic::invariant_start;
165   // Overloaded address space type.
166   llvm::Type *ObjectPtr[1] = {Int8PtrTy};
167   llvm::Function *InvariantStart = CGM.getIntrinsic(InvStartID, ObjectPtr);
168 
169   // Emit a call with the size in bytes of the object.
170   uint64_t Width = Size.getQuantity();
171   llvm::Value *Args[2] = { llvm::ConstantInt::getSigned(Int64Ty, Width),
172                            llvm::ConstantExpr::getBitCast(Addr, Int8PtrTy)};
173   Builder.CreateCall(InvariantStart, Args);
174 }
175 
176 void CodeGenFunction::EmitCXXGlobalVarDeclInit(const VarDecl &D,
177                                                llvm::GlobalVariable *GV,
178                                                bool PerformInit) {
179 
180   const Expr *Init = D.getInit();
181   QualType T = D.getType();
182 
183   // The address space of a static local variable (DeclPtr) may be different
184   // from the address space of the "this" argument of the constructor. In that
185   // case, we need an addrspacecast before calling the constructor.
186   //
187   // struct StructWithCtor {
188   //   __device__ StructWithCtor() {...}
189   // };
190   // __device__ void foo() {
191   //   __shared__ StructWithCtor s;
192   //   ...
193   // }
194   //
195   // For example, in the above CUDA code, the static local variable s has a
196   // "shared" address space qualifier, but the constructor of StructWithCtor
197   // expects "this" in the "generic" address space.
198   unsigned ExpectedAddrSpace = getTypes().getTargetAddressSpace(T);
199   unsigned ActualAddrSpace = GV->getAddressSpace();
200   llvm::Constant *DeclPtr = GV;
201   if (ActualAddrSpace != ExpectedAddrSpace) {
202     llvm::PointerType *PTy = llvm::PointerType::getWithSamePointeeType(
203         GV->getType(), ExpectedAddrSpace);
204     DeclPtr = llvm::ConstantExpr::getAddrSpaceCast(DeclPtr, PTy);
205   }
206 
207   ConstantAddress DeclAddr(
208       DeclPtr, GV->getValueType(), getContext().getDeclAlign(&D));
209 
210   if (!T->isReferenceType()) {
211     if (getLangOpts().OpenMP && !getLangOpts().OpenMPSimd &&
212         D.hasAttr<OMPThreadPrivateDeclAttr>()) {
213       (void)CGM.getOpenMPRuntime().emitThreadPrivateVarDefinition(
214           &D, DeclAddr, D.getAttr<OMPThreadPrivateDeclAttr>()->getLocation(),
215           PerformInit, this);
216     }
217     if (PerformInit)
218       EmitDeclInit(*this, D, DeclAddr);
219     if (CGM.isTypeConstant(D.getType(), true))
220       EmitDeclInvariant(*this, D, DeclPtr);
221     else
222       EmitDeclDestroy(*this, D, DeclAddr);
223     return;
224   }
225 
226   assert(PerformInit && "cannot have constant initializer which needs "
227          "destruction for reference");
228   RValue RV = EmitReferenceBindingToExpr(Init);
229   EmitStoreOfScalar(RV.getScalarVal(), DeclAddr, false, T);
230 }
231 
232 /// Create a stub function, suitable for being passed to atexit,
233 /// which passes the given address to the given destructor function.
234 llvm::Function *CodeGenFunction::createAtExitStub(const VarDecl &VD,
235                                                   llvm::FunctionCallee dtor,
236                                                   llvm::Constant *addr) {
237   // Get the destructor function type, void(*)(void).
238   llvm::FunctionType *ty = llvm::FunctionType::get(CGM.VoidTy, false);
239   SmallString<256> FnName;
240   {
241     llvm::raw_svector_ostream Out(FnName);
242     CGM.getCXXABI().getMangleContext().mangleDynamicAtExitDestructor(&VD, Out);
243   }
244 
245   const CGFunctionInfo &FI = CGM.getTypes().arrangeNullaryFunction();
246   llvm::Function *fn = CGM.CreateGlobalInitOrCleanUpFunction(
247       ty, FnName.str(), FI, VD.getLocation());
248 
249   CodeGenFunction CGF(CGM);
250 
251   CGF.StartFunction(GlobalDecl(&VD, DynamicInitKind::AtExit),
252                     CGM.getContext().VoidTy, fn, FI, FunctionArgList(),
253                     VD.getLocation(), VD.getInit()->getExprLoc());
254   // Emit an artificial location for this function.
255   auto AL = ApplyDebugLocation::CreateArtificial(CGF);
256 
257   llvm::CallInst *call = CGF.Builder.CreateCall(dtor, addr);
258 
259   // Make sure the call and the callee agree on calling convention.
260   if (auto *dtorFn = dyn_cast<llvm::Function>(
261           dtor.getCallee()->stripPointerCastsAndAliases()))
262     call->setCallingConv(dtorFn->getCallingConv());
263 
264   CGF.FinishFunction();
265 
266   return fn;
267 }
268 
269 /// Create a stub function, suitable for being passed to __pt_atexit_np,
270 /// which passes the given address to the given destructor function.
271 llvm::Function *CodeGenFunction::createTLSAtExitStub(
272     const VarDecl &D, llvm::FunctionCallee Dtor, llvm::Constant *Addr,
273     llvm::FunctionCallee &AtExit) {
274   SmallString<256> FnName;
275   {
276     llvm::raw_svector_ostream Out(FnName);
277     CGM.getCXXABI().getMangleContext().mangleDynamicAtExitDestructor(&D, Out);
278   }
279 
280   const CGFunctionInfo &FI = CGM.getTypes().arrangeLLVMFunctionInfo(
281       getContext().IntTy, /*instanceMethod=*/false, /*chainCall=*/false,
282       {getContext().IntTy}, FunctionType::ExtInfo(), {}, RequiredArgs::All);
283 
284   // Get the stub function type, int(*)(int,...).
285   llvm::FunctionType *StubTy =
286       llvm::FunctionType::get(CGM.IntTy, {CGM.IntTy}, true);
287 
288   llvm::Function *DtorStub = CGM.CreateGlobalInitOrCleanUpFunction(
289       StubTy, FnName.str(), FI, D.getLocation());
290 
291   CodeGenFunction CGF(CGM);
292 
293   FunctionArgList Args;
294   ImplicitParamDecl IPD(CGM.getContext(), CGM.getContext().IntTy,
295                         ImplicitParamDecl::Other);
296   Args.push_back(&IPD);
297   QualType ResTy = CGM.getContext().IntTy;
298 
299   CGF.StartFunction(GlobalDecl(&D, DynamicInitKind::AtExit), ResTy, DtorStub,
300                     FI, Args, D.getLocation(), D.getInit()->getExprLoc());
301 
302   // Emit an artificial location for this function.
303   auto AL = ApplyDebugLocation::CreateArtificial(CGF);
304 
305   llvm::CallInst *call = CGF.Builder.CreateCall(Dtor, Addr);
306 
307   // Make sure the call and the callee agree on calling convention.
308   if (auto *DtorFn = dyn_cast<llvm::Function>(
309           Dtor.getCallee()->stripPointerCastsAndAliases()))
310     call->setCallingConv(DtorFn->getCallingConv());
311 
312   // Return 0 from function
313   CGF.Builder.CreateStore(llvm::Constant::getNullValue(CGM.IntTy),
314                           CGF.ReturnValue);
315 
316   CGF.FinishFunction();
317 
318   return DtorStub;
319 }
320 
321 /// Register a global destructor using the C atexit runtime function.
322 void CodeGenFunction::registerGlobalDtorWithAtExit(const VarDecl &VD,
323                                                    llvm::FunctionCallee dtor,
324                                                    llvm::Constant *addr) {
325   // Create a function which calls the destructor.
326   llvm::Constant *dtorStub = createAtExitStub(VD, dtor, addr);
327   registerGlobalDtorWithAtExit(dtorStub);
328 }
329 
330 void CodeGenFunction::registerGlobalDtorWithAtExit(llvm::Constant *dtorStub) {
331   // extern "C" int atexit(void (*f)(void));
332   assert(dtorStub->getType() ==
333              llvm::PointerType::get(
334                  llvm::FunctionType::get(CGM.VoidTy, false),
335                  dtorStub->getType()->getPointerAddressSpace()) &&
336          "Argument to atexit has a wrong type.");
337 
338   llvm::FunctionType *atexitTy =
339       llvm::FunctionType::get(IntTy, dtorStub->getType(), false);
340 
341   llvm::FunctionCallee atexit =
342       CGM.CreateRuntimeFunction(atexitTy, "atexit", llvm::AttributeList(),
343                                 /*Local=*/true);
344   if (llvm::Function *atexitFn = dyn_cast<llvm::Function>(atexit.getCallee()))
345     atexitFn->setDoesNotThrow();
346 
347   EmitNounwindRuntimeCall(atexit, dtorStub);
348 }
349 
350 llvm::Value *
351 CodeGenFunction::unregisterGlobalDtorWithUnAtExit(llvm::Constant *dtorStub) {
352   // The unatexit subroutine unregisters __dtor functions that were previously
353   // registered by the atexit subroutine. If the referenced function is found,
354   // it is removed from the list of functions that are called at normal program
355   // termination and the unatexit returns a value of 0, otherwise a non-zero
356   // value is returned.
357   //
358   // extern "C" int unatexit(void (*f)(void));
359   assert(dtorStub->getType() ==
360              llvm::PointerType::get(
361                  llvm::FunctionType::get(CGM.VoidTy, false),
362                  dtorStub->getType()->getPointerAddressSpace()) &&
363          "Argument to unatexit has a wrong type.");
364 
365   llvm::FunctionType *unatexitTy =
366       llvm::FunctionType::get(IntTy, {dtorStub->getType()}, /*isVarArg=*/false);
367 
368   llvm::FunctionCallee unatexit =
369       CGM.CreateRuntimeFunction(unatexitTy, "unatexit", llvm::AttributeList());
370 
371   cast<llvm::Function>(unatexit.getCallee())->setDoesNotThrow();
372 
373   return EmitNounwindRuntimeCall(unatexit, dtorStub);
374 }
375 
376 void CodeGenFunction::EmitCXXGuardedInit(const VarDecl &D,
377                                          llvm::GlobalVariable *DeclPtr,
378                                          bool PerformInit) {
379   // If we've been asked to forbid guard variables, emit an error now.
380   // This diagnostic is hard-coded for Darwin's use case;  we can find
381   // better phrasing if someone else needs it.
382   if (CGM.getCodeGenOpts().ForbidGuardVariables)
383     CGM.Error(D.getLocation(),
384               "this initialization requires a guard variable, which "
385               "the kernel does not support");
386 
387   CGM.getCXXABI().EmitGuardedInit(*this, D, DeclPtr, PerformInit);
388 }
389 
390 void CodeGenFunction::EmitCXXGuardedInitBranch(llvm::Value *NeedsInit,
391                                                llvm::BasicBlock *InitBlock,
392                                                llvm::BasicBlock *NoInitBlock,
393                                                GuardKind Kind,
394                                                const VarDecl *D) {
395   assert((Kind == GuardKind::TlsGuard || D) && "no guarded variable");
396 
397   // A guess at how many times we will enter the initialization of a
398   // variable, depending on the kind of variable.
399   static const uint64_t InitsPerTLSVar = 1024;
400   static const uint64_t InitsPerLocalVar = 1024 * 1024;
401 
402   llvm::MDNode *Weights;
403   if (Kind == GuardKind::VariableGuard && !D->isLocalVarDecl()) {
404     // For non-local variables, don't apply any weighting for now. Due to our
405     // use of COMDATs, we expect there to be at most one initialization of the
406     // variable per DSO, but we have no way to know how many DSOs will try to
407     // initialize the variable.
408     Weights = nullptr;
409   } else {
410     uint64_t NumInits;
411     // FIXME: For the TLS case, collect and use profiling information to
412     // determine a more accurate brach weight.
413     if (Kind == GuardKind::TlsGuard || D->getTLSKind())
414       NumInits = InitsPerTLSVar;
415     else
416       NumInits = InitsPerLocalVar;
417 
418     // The probability of us entering the initializer is
419     //   1 / (total number of times we attempt to initialize the variable).
420     llvm::MDBuilder MDHelper(CGM.getLLVMContext());
421     Weights = MDHelper.createBranchWeights(1, NumInits - 1);
422   }
423 
424   Builder.CreateCondBr(NeedsInit, InitBlock, NoInitBlock, Weights);
425 }
426 
427 llvm::Function *CodeGenModule::CreateGlobalInitOrCleanUpFunction(
428     llvm::FunctionType *FTy, const Twine &Name, const CGFunctionInfo &FI,
429     SourceLocation Loc, bool TLS, llvm::GlobalVariable::LinkageTypes Linkage) {
430   llvm::Function *Fn = llvm::Function::Create(FTy, Linkage, Name, &getModule());
431 
432   if (!getLangOpts().AppleKext && !TLS) {
433     // Set the section if needed.
434     if (const char *Section = getTarget().getStaticInitSectionSpecifier())
435       Fn->setSection(Section);
436   }
437 
438   if (Linkage == llvm::GlobalVariable::InternalLinkage)
439     SetInternalFunctionAttributes(GlobalDecl(), Fn, FI);
440 
441   Fn->setCallingConv(getRuntimeCC());
442 
443   if (!getLangOpts().Exceptions)
444     Fn->setDoesNotThrow();
445 
446   if (getLangOpts().Sanitize.has(SanitizerKind::Address) &&
447       !isInNoSanitizeList(SanitizerKind::Address, Fn, Loc))
448     Fn->addFnAttr(llvm::Attribute::SanitizeAddress);
449 
450   if (getLangOpts().Sanitize.has(SanitizerKind::KernelAddress) &&
451       !isInNoSanitizeList(SanitizerKind::KernelAddress, Fn, Loc))
452     Fn->addFnAttr(llvm::Attribute::SanitizeAddress);
453 
454   if (getLangOpts().Sanitize.has(SanitizerKind::HWAddress) &&
455       !isInNoSanitizeList(SanitizerKind::HWAddress, Fn, Loc))
456     Fn->addFnAttr(llvm::Attribute::SanitizeHWAddress);
457 
458   if (getLangOpts().Sanitize.has(SanitizerKind::KernelHWAddress) &&
459       !isInNoSanitizeList(SanitizerKind::KernelHWAddress, Fn, Loc))
460     Fn->addFnAttr(llvm::Attribute::SanitizeHWAddress);
461 
462   if (getLangOpts().Sanitize.has(SanitizerKind::MemtagStack) &&
463       !isInNoSanitizeList(SanitizerKind::MemtagStack, Fn, Loc))
464     Fn->addFnAttr(llvm::Attribute::SanitizeMemTag);
465 
466   if (getLangOpts().Sanitize.has(SanitizerKind::Thread) &&
467       !isInNoSanitizeList(SanitizerKind::Thread, Fn, Loc))
468     Fn->addFnAttr(llvm::Attribute::SanitizeThread);
469 
470   if (getLangOpts().Sanitize.has(SanitizerKind::Memory) &&
471       !isInNoSanitizeList(SanitizerKind::Memory, Fn, Loc))
472     Fn->addFnAttr(llvm::Attribute::SanitizeMemory);
473 
474   if (getLangOpts().Sanitize.has(SanitizerKind::KernelMemory) &&
475       !isInNoSanitizeList(SanitizerKind::KernelMemory, Fn, Loc))
476     Fn->addFnAttr(llvm::Attribute::SanitizeMemory);
477 
478   if (getLangOpts().Sanitize.has(SanitizerKind::SafeStack) &&
479       !isInNoSanitizeList(SanitizerKind::SafeStack, Fn, Loc))
480     Fn->addFnAttr(llvm::Attribute::SafeStack);
481 
482   if (getLangOpts().Sanitize.has(SanitizerKind::ShadowCallStack) &&
483       !isInNoSanitizeList(SanitizerKind::ShadowCallStack, Fn, Loc))
484     Fn->addFnAttr(llvm::Attribute::ShadowCallStack);
485 
486   return Fn;
487 }
488 
489 /// Create a global pointer to a function that will initialize a global
490 /// variable.  The user has requested that this pointer be emitted in a specific
491 /// section.
492 void CodeGenModule::EmitPointerToInitFunc(const VarDecl *D,
493                                           llvm::GlobalVariable *GV,
494                                           llvm::Function *InitFunc,
495                                           InitSegAttr *ISA) {
496   llvm::GlobalVariable *PtrArray = new llvm::GlobalVariable(
497       TheModule, InitFunc->getType(), /*isConstant=*/true,
498       llvm::GlobalValue::PrivateLinkage, InitFunc, "__cxx_init_fn_ptr");
499   PtrArray->setSection(ISA->getSection());
500   addUsedGlobal(PtrArray);
501 
502   // If the GV is already in a comdat group, then we have to join it.
503   if (llvm::Comdat *C = GV->getComdat())
504     PtrArray->setComdat(C);
505 }
506 
507 void
508 CodeGenModule::EmitCXXGlobalVarDeclInitFunc(const VarDecl *D,
509                                             llvm::GlobalVariable *Addr,
510                                             bool PerformInit) {
511 
512   // According to E.2.3.1 in CUDA-7.5 Programming guide: __device__,
513   // __constant__ and __shared__ variables defined in namespace scope,
514   // that are of class type, cannot have a non-empty constructor. All
515   // the checks have been done in Sema by now. Whatever initializers
516   // are allowed are empty and we just need to ignore them here.
517   if (getLangOpts().CUDAIsDevice && !getLangOpts().GPUAllowDeviceInit &&
518       (D->hasAttr<CUDADeviceAttr>() || D->hasAttr<CUDAConstantAttr>() ||
519        D->hasAttr<CUDASharedAttr>()))
520     return;
521 
522   if (getLangOpts().OpenMP &&
523       getOpenMPRuntime().emitDeclareTargetVarDefinition(D, Addr, PerformInit))
524     return;
525 
526   // Check if we've already initialized this decl.
527   auto I = DelayedCXXInitPosition.find(D);
528   if (I != DelayedCXXInitPosition.end() && I->second == ~0U)
529     return;
530 
531   llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
532   SmallString<256> FnName;
533   {
534     llvm::raw_svector_ostream Out(FnName);
535     getCXXABI().getMangleContext().mangleDynamicInitializer(D, Out);
536   }
537 
538   // Create a variable initialization function.
539   llvm::Function *Fn = CreateGlobalInitOrCleanUpFunction(
540       FTy, FnName.str(), getTypes().arrangeNullaryFunction(), D->getLocation());
541 
542   auto *ISA = D->getAttr<InitSegAttr>();
543   CodeGenFunction(*this).GenerateCXXGlobalVarDeclInitFunc(Fn, D, Addr,
544                                                           PerformInit);
545 
546   llvm::GlobalVariable *COMDATKey =
547       supportsCOMDAT() && D->isExternallyVisible() ? Addr : nullptr;
548 
549   if (D->getTLSKind()) {
550     // FIXME: Should we support init_priority for thread_local?
551     // FIXME: We only need to register one __cxa_thread_atexit function for the
552     // entire TU.
553     CXXThreadLocalInits.push_back(Fn);
554     CXXThreadLocalInitVars.push_back(D);
555   } else if (PerformInit && ISA) {
556     // Contract with backend that "init_seg(compiler)" corresponds to priority
557     // 200 and "init_seg(lib)" corresponds to priority 400.
558     int Priority = -1;
559     if (ISA->getSection() == ".CRT$XCC")
560       Priority = 200;
561     else if (ISA->getSection() == ".CRT$XCL")
562       Priority = 400;
563 
564     if (Priority != -1)
565       AddGlobalCtor(Fn, Priority, ~0U, COMDATKey);
566     else
567       EmitPointerToInitFunc(D, Addr, Fn, ISA);
568   } else if (auto *IPA = D->getAttr<InitPriorityAttr>()) {
569     OrderGlobalInitsOrStermFinalizers Key(IPA->getPriority(),
570                                           PrioritizedCXXGlobalInits.size());
571     PrioritizedCXXGlobalInits.push_back(std::make_pair(Key, Fn));
572   } else if (isTemplateInstantiation(D->getTemplateSpecializationKind()) ||
573              getContext().GetGVALinkageForVariable(D) == GVA_DiscardableODR ||
574              D->hasAttr<SelectAnyAttr>()) {
575     // C++ [basic.start.init]p2:
576     //   Definitions of explicitly specialized class template static data
577     //   members have ordered initialization. Other class template static data
578     //   members (i.e., implicitly or explicitly instantiated specializations)
579     //   have unordered initialization.
580     //
581     // As a consequence, we can put them into their own llvm.global_ctors entry.
582     //
583     // If the global is externally visible, put the initializer into a COMDAT
584     // group with the global being initialized.  On most platforms, this is a
585     // minor startup time optimization.  In the MS C++ ABI, there are no guard
586     // variables, so this COMDAT key is required for correctness.
587     //
588     // SelectAny globals will be comdat-folded. Put the initializer into a
589     // COMDAT group associated with the global, so the initializers get folded
590     // too.
591     I = DelayedCXXInitPosition.find(D);
592     // CXXGlobalInits.size() is the lex order number for the next deferred
593     // VarDecl. Use it when the current VarDecl is non-deferred. Although this
594     // lex order number is shared between current VarDecl and some following
595     // VarDecls, their order of insertion into `llvm.global_ctors` is the same
596     // as the lexing order and the following stable sort would preserve such
597     // order.
598     unsigned LexOrder =
599         I == DelayedCXXInitPosition.end() ? CXXGlobalInits.size() : I->second;
600     AddGlobalCtor(Fn, 65535, LexOrder, COMDATKey);
601     if (COMDATKey && (getTriple().isOSBinFormatELF() ||
602                       getTarget().getCXXABI().isMicrosoft())) {
603       // When COMDAT is used on ELF or in the MS C++ ABI, the key must be in
604       // llvm.used to prevent linker GC.
605       addUsedGlobal(COMDATKey);
606     }
607 
608     // If we used a COMDAT key for the global ctor, the init function can be
609     // discarded if the global ctor entry is discarded.
610     // FIXME: Do we need to restrict this to ELF and Wasm?
611     llvm::Comdat *C = Addr->getComdat();
612     if (COMDATKey && C &&
613         (getTarget().getTriple().isOSBinFormatELF() ||
614          getTarget().getTriple().isOSBinFormatWasm())) {
615       Fn->setComdat(C);
616     }
617   } else {
618     I = DelayedCXXInitPosition.find(D); // Re-do lookup in case of re-hash.
619     if (I == DelayedCXXInitPosition.end()) {
620       CXXGlobalInits.push_back(Fn);
621     } else if (I->second != ~0U) {
622       assert(I->second < CXXGlobalInits.size() &&
623              CXXGlobalInits[I->second] == nullptr);
624       CXXGlobalInits[I->second] = Fn;
625     }
626   }
627 
628   // Remember that we already emitted the initializer for this global.
629   DelayedCXXInitPosition[D] = ~0U;
630 }
631 
632 void CodeGenModule::EmitCXXThreadLocalInitFunc() {
633   getCXXABI().EmitThreadLocalInitFuncs(
634       *this, CXXThreadLocals, CXXThreadLocalInits, CXXThreadLocalInitVars);
635 
636   CXXThreadLocalInits.clear();
637   CXXThreadLocalInitVars.clear();
638   CXXThreadLocals.clear();
639 }
640 
641 /* Build the initializer for a C++20 module:
642    This is arranged to be run only once regardless of how many times the module
643    might be included transitively.  This arranged by using a guard variable.
644 
645    If there are no initalizers at all (and also no imported modules) we reduce
646    this to an empty function (since the Itanium ABI requires that this function
647    be available to a caller, which might be produced by a different
648    implementation).
649 
650    First we call any initializers for imported modules.
651    We then call initializers for the Global Module Fragment (if present)
652    We then call initializers for the current module.
653    We then call initializers for the Private Module Fragment (if present)
654 */
655 
656 void CodeGenModule::EmitCXXModuleInitFunc(Module *Primary) {
657   while (!CXXGlobalInits.empty() && !CXXGlobalInits.back())
658     CXXGlobalInits.pop_back();
659 
660   // As noted above, we create the function, even if it is empty.
661   // Module initializers for imported modules are emitted first.
662 
663   // Collect all the modules that we import
664   SmallVector<Module *> AllImports;
665   // Ones that we export
666   for (auto I : Primary->Exports)
667     AllImports.push_back(I.getPointer());
668   // Ones that we only import.
669   for (Module *M : Primary->Imports)
670     AllImports.push_back(M);
671 
672   SmallVector<llvm::Function *, 8> ModuleInits;
673   for (Module *M : AllImports) {
674     // No Itanium initializer in header like modules.
675     if (M->isHeaderLikeModule())
676       continue; // TODO: warn of mixed use of module map modules and C++20?
677     llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
678     SmallString<256> FnName;
679     {
680       llvm::raw_svector_ostream Out(FnName);
681       cast<ItaniumMangleContext>(getCXXABI().getMangleContext())
682           .mangleModuleInitializer(M, Out);
683     }
684     assert(!GetGlobalValue(FnName.str()) &&
685            "We should only have one use of the initializer call");
686     llvm::Function *Fn = llvm::Function::Create(
687         FTy, llvm::Function::ExternalLinkage, FnName.str(), &getModule());
688     ModuleInits.push_back(Fn);
689   }
690 
691   // Add any initializers with specified priority; this uses the same  approach
692   // as EmitCXXGlobalInitFunc().
693   if (!PrioritizedCXXGlobalInits.empty()) {
694     SmallVector<llvm::Function *, 8> LocalCXXGlobalInits;
695     llvm::array_pod_sort(PrioritizedCXXGlobalInits.begin(),
696                          PrioritizedCXXGlobalInits.end());
697     for (SmallVectorImpl<GlobalInitData>::iterator
698              I = PrioritizedCXXGlobalInits.begin(),
699              E = PrioritizedCXXGlobalInits.end();
700          I != E;) {
701       SmallVectorImpl<GlobalInitData>::iterator PrioE =
702           std::upper_bound(I + 1, E, *I, GlobalInitPriorityCmp());
703 
704       for (; I < PrioE; ++I)
705         ModuleInits.push_back(I->second);
706     }
707   }
708 
709   // Now append the ones without specified priority.
710   for (auto *F : CXXGlobalInits)
711     ModuleInits.push_back(F);
712 
713   llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
714   const CGFunctionInfo &FI = getTypes().arrangeNullaryFunction();
715 
716   // We now build the initializer for this module, which has a mangled name
717   // as per the Itanium ABI .  The action of the initializer is guarded so that
718   // each init is run just once (even though a module might be imported
719   // multiple times via nested use).
720   llvm::Function *Fn;
721   {
722     SmallString<256> InitFnName;
723     llvm::raw_svector_ostream Out(InitFnName);
724     cast<ItaniumMangleContext>(getCXXABI().getMangleContext())
725         .mangleModuleInitializer(Primary, Out);
726     Fn = CreateGlobalInitOrCleanUpFunction(
727         FTy, llvm::Twine(InitFnName), FI, SourceLocation(), false,
728         llvm::GlobalVariable::ExternalLinkage);
729 
730     // If we have a completely empty initializer then we do not want to create
731     // the guard variable.
732     ConstantAddress GuardAddr = ConstantAddress::invalid();
733     if (!AllImports.empty() || !PrioritizedCXXGlobalInits.empty() ||
734         !CXXGlobalInits.empty()) {
735       // Create the guard var.
736       llvm::GlobalVariable *Guard = new llvm::GlobalVariable(
737           getModule(), Int8Ty, /*isConstant=*/false,
738           llvm::GlobalVariable::InternalLinkage,
739           llvm::ConstantInt::get(Int8Ty, 0), InitFnName.str() + "__in_chrg");
740       CharUnits GuardAlign = CharUnits::One();
741       Guard->setAlignment(GuardAlign.getAsAlign());
742       GuardAddr = ConstantAddress(Guard, Int8Ty, GuardAlign);
743     }
744     CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn, ModuleInits,
745                                                      GuardAddr);
746   }
747 
748   // We allow for the case that a module object is added to a linked binary
749   // without a specific call to the the initializer.  This also ensures that
750   // implementation partition initializers are called when the partition
751   // is not imported as an interface.
752   AddGlobalCtor(Fn);
753 
754   // See the comment in EmitCXXGlobalInitFunc about OpenCL global init
755   // functions.
756   if (getLangOpts().OpenCL) {
757     GenKernelArgMetadata(Fn);
758     Fn->setCallingConv(llvm::CallingConv::SPIR_KERNEL);
759   }
760 
761   assert(!getLangOpts().CUDA || !getLangOpts().CUDAIsDevice ||
762          getLangOpts().GPUAllowDeviceInit);
763   if (getLangOpts().HIP && getLangOpts().CUDAIsDevice) {
764     Fn->setCallingConv(llvm::CallingConv::AMDGPU_KERNEL);
765     Fn->addFnAttr("device-init");
766   }
767 
768   // We are done with the inits.
769   AllImports.clear();
770   PrioritizedCXXGlobalInits.clear();
771   CXXGlobalInits.clear();
772   ModuleInits.clear();
773 }
774 
775 static SmallString<128> getTransformedFileName(llvm::Module &M) {
776   SmallString<128> FileName = llvm::sys::path::filename(M.getName());
777 
778   if (FileName.empty())
779     FileName = "<null>";
780 
781   for (size_t i = 0; i < FileName.size(); ++i) {
782     // Replace everything that's not [a-zA-Z0-9._] with a _. This set happens
783     // to be the set of C preprocessing numbers.
784     if (!isPreprocessingNumberBody(FileName[i]))
785       FileName[i] = '_';
786   }
787 
788   return FileName;
789 }
790 
791 static std::string getPrioritySuffix(unsigned int Priority) {
792   assert(Priority <= 65535 && "Priority should always be <= 65535.");
793 
794   // Compute the function suffix from priority. Prepend with zeroes to make
795   // sure the function names are also ordered as priorities.
796   std::string PrioritySuffix = llvm::utostr(Priority);
797   PrioritySuffix = std::string(6 - PrioritySuffix.size(), '0') + PrioritySuffix;
798 
799   return PrioritySuffix;
800 }
801 
802 void
803 CodeGenModule::EmitCXXGlobalInitFunc() {
804   while (!CXXGlobalInits.empty() && !CXXGlobalInits.back())
805     CXXGlobalInits.pop_back();
806 
807   // When we import C++20 modules, we must run their initializers first.
808   SmallVector<llvm::Function *, 8> ModuleInits;
809   if (CXX20ModuleInits)
810     for (Module *M : ImportedModules) {
811       // No Itanium initializer in header like modules.
812       if (M->isHeaderLikeModule())
813         continue;
814       llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
815       SmallString<256> FnName;
816       {
817         llvm::raw_svector_ostream Out(FnName);
818         cast<ItaniumMangleContext>(getCXXABI().getMangleContext())
819             .mangleModuleInitializer(M, Out);
820       }
821       assert(!GetGlobalValue(FnName.str()) &&
822              "We should only have one use of the initializer call");
823       llvm::Function *Fn = llvm::Function::Create(
824           FTy, llvm::Function::ExternalLinkage, FnName.str(), &getModule());
825       ModuleInits.push_back(Fn);
826     }
827 
828   if (ModuleInits.empty() && CXXGlobalInits.empty() &&
829       PrioritizedCXXGlobalInits.empty())
830     return;
831 
832   llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
833   const CGFunctionInfo &FI = getTypes().arrangeNullaryFunction();
834 
835   // Create our global prioritized initialization function.
836   if (!PrioritizedCXXGlobalInits.empty()) {
837     SmallVector<llvm::Function *, 8> LocalCXXGlobalInits;
838     llvm::array_pod_sort(PrioritizedCXXGlobalInits.begin(),
839                          PrioritizedCXXGlobalInits.end());
840     // Iterate over "chunks" of ctors with same priority and emit each chunk
841     // into separate function. Note - everything is sorted first by priority,
842     // second - by lex order, so we emit ctor functions in proper order.
843     for (SmallVectorImpl<GlobalInitData >::iterator
844            I = PrioritizedCXXGlobalInits.begin(),
845            E = PrioritizedCXXGlobalInits.end(); I != E; ) {
846       SmallVectorImpl<GlobalInitData >::iterator
847         PrioE = std::upper_bound(I + 1, E, *I, GlobalInitPriorityCmp());
848 
849       LocalCXXGlobalInits.clear();
850 
851       unsigned int Priority = I->first.priority;
852       llvm::Function *Fn = CreateGlobalInitOrCleanUpFunction(
853           FTy, "_GLOBAL__I_" + getPrioritySuffix(Priority), FI);
854 
855       // Prepend the module inits to the highest priority set.
856       if (!ModuleInits.empty()) {
857         for (auto *F : ModuleInits)
858           LocalCXXGlobalInits.push_back(F);
859         ModuleInits.clear();
860       }
861 
862       for (; I < PrioE; ++I)
863         LocalCXXGlobalInits.push_back(I->second);
864 
865       CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn, LocalCXXGlobalInits);
866       AddGlobalCtor(Fn, Priority);
867     }
868     PrioritizedCXXGlobalInits.clear();
869   }
870 
871   if (getCXXABI().useSinitAndSterm() && ModuleInits.empty() &&
872       CXXGlobalInits.empty())
873     return;
874 
875   for (auto *F : CXXGlobalInits)
876     ModuleInits.push_back(F);
877   CXXGlobalInits.clear();
878 
879   // Include the filename in the symbol name. Including "sub_" matches gcc
880   // and makes sure these symbols appear lexicographically behind the symbols
881   // with priority emitted above.
882   llvm::Function *Fn;
883   if (CXX20ModuleInits && getContext().getModuleForCodeGen()) {
884     SmallString<256> InitFnName;
885     llvm::raw_svector_ostream Out(InitFnName);
886     cast<ItaniumMangleContext>(getCXXABI().getMangleContext())
887         .mangleModuleInitializer(getContext().getModuleForCodeGen(), Out);
888     Fn = CreateGlobalInitOrCleanUpFunction(
889         FTy, llvm::Twine(InitFnName), FI, SourceLocation(), false,
890         llvm::GlobalVariable::ExternalLinkage);
891   } else
892     Fn = CreateGlobalInitOrCleanUpFunction(
893         FTy,
894         llvm::Twine("_GLOBAL__sub_I_", getTransformedFileName(getModule())),
895         FI);
896 
897   CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn, ModuleInits);
898   AddGlobalCtor(Fn);
899 
900   // In OpenCL global init functions must be converted to kernels in order to
901   // be able to launch them from the host.
902   // FIXME: Some more work might be needed to handle destructors correctly.
903   // Current initialization function makes use of function pointers callbacks.
904   // We can't support function pointers especially between host and device.
905   // However it seems global destruction has little meaning without any
906   // dynamic resource allocation on the device and program scope variables are
907   // destroyed by the runtime when program is released.
908   if (getLangOpts().OpenCL) {
909     GenKernelArgMetadata(Fn);
910     Fn->setCallingConv(llvm::CallingConv::SPIR_KERNEL);
911   }
912 
913   assert(!getLangOpts().CUDA || !getLangOpts().CUDAIsDevice ||
914          getLangOpts().GPUAllowDeviceInit);
915   if (getLangOpts().HIP && getLangOpts().CUDAIsDevice) {
916     Fn->setCallingConv(llvm::CallingConv::AMDGPU_KERNEL);
917     Fn->addFnAttr("device-init");
918   }
919 
920   ModuleInits.clear();
921 }
922 
923 void CodeGenModule::EmitCXXGlobalCleanUpFunc() {
924   if (CXXGlobalDtorsOrStermFinalizers.empty() &&
925       PrioritizedCXXStermFinalizers.empty())
926     return;
927 
928   llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
929   const CGFunctionInfo &FI = getTypes().arrangeNullaryFunction();
930 
931   // Create our global prioritized cleanup function.
932   if (!PrioritizedCXXStermFinalizers.empty()) {
933     SmallVector<CXXGlobalDtorsOrStermFinalizer_t, 8> LocalCXXStermFinalizers;
934     llvm::array_pod_sort(PrioritizedCXXStermFinalizers.begin(),
935                          PrioritizedCXXStermFinalizers.end());
936     // Iterate over "chunks" of dtors with same priority and emit each chunk
937     // into separate function. Note - everything is sorted first by priority,
938     // second - by lex order, so we emit dtor functions in proper order.
939     for (SmallVectorImpl<StermFinalizerData>::iterator
940              I = PrioritizedCXXStermFinalizers.begin(),
941              E = PrioritizedCXXStermFinalizers.end();
942          I != E;) {
943       SmallVectorImpl<StermFinalizerData>::iterator PrioE =
944           std::upper_bound(I + 1, E, *I, StermFinalizerPriorityCmp());
945 
946       LocalCXXStermFinalizers.clear();
947 
948       unsigned int Priority = I->first.priority;
949       llvm::Function *Fn = CreateGlobalInitOrCleanUpFunction(
950           FTy, "_GLOBAL__a_" + getPrioritySuffix(Priority), FI);
951 
952       for (; I < PrioE; ++I) {
953         llvm::FunctionCallee DtorFn = I->second;
954         LocalCXXStermFinalizers.emplace_back(DtorFn.getFunctionType(),
955                                              DtorFn.getCallee(), nullptr);
956       }
957 
958       CodeGenFunction(*this).GenerateCXXGlobalCleanUpFunc(
959           Fn, LocalCXXStermFinalizers);
960       AddGlobalDtor(Fn, Priority);
961     }
962     PrioritizedCXXStermFinalizers.clear();
963   }
964 
965   if (CXXGlobalDtorsOrStermFinalizers.empty())
966     return;
967 
968   // Create our global cleanup function.
969   llvm::Function *Fn =
970       CreateGlobalInitOrCleanUpFunction(FTy, "_GLOBAL__D_a", FI);
971 
972   CodeGenFunction(*this).GenerateCXXGlobalCleanUpFunc(
973       Fn, CXXGlobalDtorsOrStermFinalizers);
974   AddGlobalDtor(Fn);
975   CXXGlobalDtorsOrStermFinalizers.clear();
976 }
977 
978 /// Emit the code necessary to initialize the given global variable.
979 void CodeGenFunction::GenerateCXXGlobalVarDeclInitFunc(llvm::Function *Fn,
980                                                        const VarDecl *D,
981                                                  llvm::GlobalVariable *Addr,
982                                                        bool PerformInit) {
983   // Check if we need to emit debug info for variable initializer.
984   if (D->hasAttr<NoDebugAttr>())
985     DebugInfo = nullptr; // disable debug info indefinitely for this function
986 
987   CurEHLocation = D->getBeginLoc();
988 
989   StartFunction(GlobalDecl(D, DynamicInitKind::Initializer),
990                 getContext().VoidTy, Fn, getTypes().arrangeNullaryFunction(),
991                 FunctionArgList());
992   // Emit an artificial location for this function.
993   auto AL = ApplyDebugLocation::CreateArtificial(*this);
994 
995   // Use guarded initialization if the global variable is weak. This
996   // occurs for, e.g., instantiated static data members and
997   // definitions explicitly marked weak.
998   //
999   // Also use guarded initialization for a variable with dynamic TLS and
1000   // unordered initialization. (If the initialization is ordered, the ABI
1001   // layer will guard the whole-TU initialization for us.)
1002   if (Addr->hasWeakLinkage() || Addr->hasLinkOnceLinkage() ||
1003       (D->getTLSKind() == VarDecl::TLS_Dynamic &&
1004        isTemplateInstantiation(D->getTemplateSpecializationKind()))) {
1005     EmitCXXGuardedInit(*D, Addr, PerformInit);
1006   } else {
1007     EmitCXXGlobalVarDeclInit(*D, Addr, PerformInit);
1008   }
1009 
1010   if (getLangOpts().HLSL)
1011     CGM.getHLSLRuntime().annotateHLSLResource(D, Addr);
1012 
1013   FinishFunction();
1014 }
1015 
1016 void
1017 CodeGenFunction::GenerateCXXGlobalInitFunc(llvm::Function *Fn,
1018                                            ArrayRef<llvm::Function *> Decls,
1019                                            ConstantAddress Guard) {
1020   {
1021     auto NL = ApplyDebugLocation::CreateEmpty(*this);
1022     StartFunction(GlobalDecl(), getContext().VoidTy, Fn,
1023                   getTypes().arrangeNullaryFunction(), FunctionArgList());
1024     // Emit an artificial location for this function.
1025     auto AL = ApplyDebugLocation::CreateArtificial(*this);
1026 
1027     llvm::BasicBlock *ExitBlock = nullptr;
1028     if (Guard.isValid()) {
1029       // If we have a guard variable, check whether we've already performed
1030       // these initializations. This happens for TLS initialization functions.
1031       llvm::Value *GuardVal = Builder.CreateLoad(Guard);
1032       llvm::Value *Uninit = Builder.CreateIsNull(GuardVal,
1033                                                  "guard.uninitialized");
1034       llvm::BasicBlock *InitBlock = createBasicBlock("init");
1035       ExitBlock = createBasicBlock("exit");
1036       EmitCXXGuardedInitBranch(Uninit, InitBlock, ExitBlock,
1037                                GuardKind::TlsGuard, nullptr);
1038       EmitBlock(InitBlock);
1039       // Mark as initialized before initializing anything else. If the
1040       // initializers use previously-initialized thread_local vars, that's
1041       // probably supposed to be OK, but the standard doesn't say.
1042       Builder.CreateStore(llvm::ConstantInt::get(GuardVal->getType(),1), Guard);
1043 
1044       // The guard variable can't ever change again.
1045       EmitInvariantStart(
1046           Guard.getPointer(),
1047           CharUnits::fromQuantity(
1048               CGM.getDataLayout().getTypeAllocSize(GuardVal->getType())));
1049     }
1050 
1051     RunCleanupsScope Scope(*this);
1052 
1053     // When building in Objective-C++ ARC mode, create an autorelease pool
1054     // around the global initializers.
1055     if (getLangOpts().ObjCAutoRefCount && getLangOpts().CPlusPlus) {
1056       llvm::Value *token = EmitObjCAutoreleasePoolPush();
1057       EmitObjCAutoreleasePoolCleanup(token);
1058     }
1059 
1060     for (unsigned i = 0, e = Decls.size(); i != e; ++i)
1061       if (Decls[i])
1062         EmitRuntimeCall(Decls[i]);
1063 
1064     Scope.ForceCleanup();
1065 
1066     if (ExitBlock) {
1067       Builder.CreateBr(ExitBlock);
1068       EmitBlock(ExitBlock);
1069     }
1070   }
1071 
1072   FinishFunction();
1073 }
1074 
1075 void CodeGenFunction::GenerateCXXGlobalCleanUpFunc(
1076     llvm::Function *Fn,
1077     ArrayRef<std::tuple<llvm::FunctionType *, llvm::WeakTrackingVH,
1078                         llvm::Constant *>>
1079         DtorsOrStermFinalizers) {
1080   {
1081     auto NL = ApplyDebugLocation::CreateEmpty(*this);
1082     StartFunction(GlobalDecl(), getContext().VoidTy, Fn,
1083                   getTypes().arrangeNullaryFunction(), FunctionArgList());
1084     // Emit an artificial location for this function.
1085     auto AL = ApplyDebugLocation::CreateArtificial(*this);
1086 
1087     // Emit the cleanups, in reverse order from construction.
1088     for (unsigned i = 0, e = DtorsOrStermFinalizers.size(); i != e; ++i) {
1089       llvm::FunctionType *CalleeTy;
1090       llvm::Value *Callee;
1091       llvm::Constant *Arg;
1092       std::tie(CalleeTy, Callee, Arg) = DtorsOrStermFinalizers[e - i - 1];
1093 
1094       llvm::CallInst *CI = nullptr;
1095       if (Arg == nullptr) {
1096         assert(
1097             CGM.getCXXABI().useSinitAndSterm() &&
1098             "Arg could not be nullptr unless using sinit and sterm functions.");
1099         CI = Builder.CreateCall(CalleeTy, Callee);
1100       } else
1101         CI = Builder.CreateCall(CalleeTy, Callee, Arg);
1102 
1103       // Make sure the call and the callee agree on calling convention.
1104       if (llvm::Function *F = dyn_cast<llvm::Function>(Callee))
1105         CI->setCallingConv(F->getCallingConv());
1106     }
1107   }
1108 
1109   FinishFunction();
1110 }
1111 
1112 /// generateDestroyHelper - Generates a helper function which, when
1113 /// invoked, destroys the given object.  The address of the object
1114 /// should be in global memory.
1115 llvm::Function *CodeGenFunction::generateDestroyHelper(
1116     Address addr, QualType type, Destroyer *destroyer,
1117     bool useEHCleanupForArray, const VarDecl *VD) {
1118   FunctionArgList args;
1119   ImplicitParamDecl Dst(getContext(), getContext().VoidPtrTy,
1120                         ImplicitParamDecl::Other);
1121   args.push_back(&Dst);
1122 
1123   const CGFunctionInfo &FI =
1124     CGM.getTypes().arrangeBuiltinFunctionDeclaration(getContext().VoidTy, args);
1125   llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(FI);
1126   llvm::Function *fn = CGM.CreateGlobalInitOrCleanUpFunction(
1127       FTy, "__cxx_global_array_dtor", FI, VD->getLocation());
1128 
1129   CurEHLocation = VD->getBeginLoc();
1130 
1131   StartFunction(GlobalDecl(VD, DynamicInitKind::GlobalArrayDestructor),
1132                 getContext().VoidTy, fn, FI, args);
1133   // Emit an artificial location for this function.
1134   auto AL = ApplyDebugLocation::CreateArtificial(*this);
1135 
1136   emitDestroy(addr, type, destroyer, useEHCleanupForArray);
1137 
1138   FinishFunction();
1139 
1140   return fn;
1141 }
1142