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 "CGObjCRuntime.h"
15 #include "CGOpenMPRuntime.h"
16 #include "CodeGenFunction.h"
17 #include "TargetInfo.h"
18 #include "clang/AST/Attr.h"
19 #include "clang/Basic/LangOptions.h"
20 #include "llvm/ADT/StringExtras.h"
21 #include "llvm/IR/Intrinsics.h"
22 #include "llvm/IR/MDBuilder.h"
23 #include "llvm/Support/Path.h"
24
25 using namespace clang;
26 using namespace CodeGen;
27
EmitDeclInit(CodeGenFunction & CGF,const VarDecl & D,ConstantAddress DeclPtr)28 static void EmitDeclInit(CodeGenFunction &CGF, const VarDecl &D,
29 ConstantAddress DeclPtr) {
30 assert(
31 (D.hasGlobalStorage() ||
32 (D.hasLocalStorage() && CGF.getContext().getLangOpts().OpenCLCPlusPlus)) &&
33 "VarDecl must have global or local (in the case of OpenCL) storage!");
34 assert(!D.getType()->isReferenceType() &&
35 "Should not call EmitDeclInit on a reference!");
36
37 QualType type = D.getType();
38 LValue lv = CGF.MakeAddrLValue(DeclPtr, type);
39
40 const Expr *Init = D.getInit();
41 switch (CGF.getEvaluationKind(type)) {
42 case TEK_Scalar: {
43 CodeGenModule &CGM = CGF.CGM;
44 if (lv.isObjCStrong())
45 CGM.getObjCRuntime().EmitObjCGlobalAssign(CGF, CGF.EmitScalarExpr(Init),
46 DeclPtr, D.getTLSKind());
47 else if (lv.isObjCWeak())
48 CGM.getObjCRuntime().EmitObjCWeakAssign(CGF, CGF.EmitScalarExpr(Init),
49 DeclPtr);
50 else
51 CGF.EmitScalarInit(Init, &D, lv, false);
52 return;
53 }
54 case TEK_Complex:
55 CGF.EmitComplexExprIntoLValue(Init, lv, /*isInit*/ true);
56 return;
57 case TEK_Aggregate:
58 CGF.EmitAggExpr(Init,
59 AggValueSlot::forLValue(lv, CGF, AggValueSlot::IsDestructed,
60 AggValueSlot::DoesNotNeedGCBarriers,
61 AggValueSlot::IsNotAliased,
62 AggValueSlot::DoesNotOverlap));
63 return;
64 }
65 llvm_unreachable("bad evaluation kind");
66 }
67
68 /// Emit code to cause the destruction of the given variable with
69 /// static storage duration.
EmitDeclDestroy(CodeGenFunction & CGF,const VarDecl & D,ConstantAddress Addr)70 static void EmitDeclDestroy(CodeGenFunction &CGF, const VarDecl &D,
71 ConstantAddress Addr) {
72 // Honor __attribute__((no_destroy)) and bail instead of attempting
73 // to emit a reference to a possibly nonexistent destructor, which
74 // in turn can cause a crash. This will result in a global constructor
75 // that isn't balanced out by a destructor call as intended by the
76 // attribute. This also checks for -fno-c++-static-destructors and
77 // bails even if the attribute is not present.
78 QualType::DestructionKind DtorKind = D.needsDestruction(CGF.getContext());
79
80 // FIXME: __attribute__((cleanup)) ?
81
82 switch (DtorKind) {
83 case QualType::DK_none:
84 return;
85
86 case QualType::DK_cxx_destructor:
87 break;
88
89 case QualType::DK_objc_strong_lifetime:
90 case QualType::DK_objc_weak_lifetime:
91 case QualType::DK_nontrivial_c_struct:
92 // We don't care about releasing objects during process teardown.
93 assert(!D.getTLSKind() && "should have rejected this");
94 return;
95 }
96
97 llvm::FunctionCallee Func;
98 llvm::Constant *Argument;
99
100 CodeGenModule &CGM = CGF.CGM;
101 QualType Type = D.getType();
102
103 // Special-case non-array C++ destructors, if they have the right signature.
104 // Under some ABIs, destructors return this instead of void, and cannot be
105 // passed directly to __cxa_atexit if the target does not allow this
106 // mismatch.
107 const CXXRecordDecl *Record = Type->getAsCXXRecordDecl();
108 bool CanRegisterDestructor =
109 Record && (!CGM.getCXXABI().HasThisReturn(
110 GlobalDecl(Record->getDestructor(), Dtor_Complete)) ||
111 CGM.getCXXABI().canCallMismatchedFunctionType());
112 // If __cxa_atexit is disabled via a flag, a different helper function is
113 // generated elsewhere which uses atexit instead, and it takes the destructor
114 // directly.
115 bool UsingExternalHelper = !CGM.getCodeGenOpts().CXAAtExit;
116 if (Record && (CanRegisterDestructor || UsingExternalHelper)) {
117 assert(!Record->hasTrivialDestructor());
118 CXXDestructorDecl *Dtor = Record->getDestructor();
119
120 Func = CGM.getAddrAndTypeOfCXXStructor(GlobalDecl(Dtor, Dtor_Complete));
121 if (CGF.getContext().getLangOpts().OpenCL) {
122 auto DestAS =
123 CGM.getTargetCodeGenInfo().getAddrSpaceOfCxaAtexitPtrParam();
124 auto DestTy = CGF.getTypes().ConvertType(Type)->getPointerTo(
125 CGM.getContext().getTargetAddressSpace(DestAS));
126 auto SrcAS = D.getType().getQualifiers().getAddressSpace();
127 if (DestAS == SrcAS)
128 Argument = llvm::ConstantExpr::getBitCast(Addr.getPointer(), DestTy);
129 else
130 // FIXME: On addr space mismatch we are passing NULL. The generation
131 // of the global destructor function should be adjusted accordingly.
132 Argument = llvm::ConstantPointerNull::get(DestTy);
133 } else {
134 Argument = llvm::ConstantExpr::getBitCast(
135 Addr.getPointer(), CGF.getTypes().ConvertType(Type)->getPointerTo());
136 }
137 // Otherwise, the standard logic requires a helper function.
138 } else {
139 Func = CodeGenFunction(CGM)
140 .generateDestroyHelper(Addr, Type, CGF.getDestroyer(DtorKind),
141 CGF.needsEHCleanup(DtorKind), &D);
142 Argument = llvm::Constant::getNullValue(CGF.Int8PtrTy);
143 }
144
145 CGM.getCXXABI().registerGlobalDtor(CGF, D, Func, Argument);
146 }
147
148 /// Emit code to cause the variable at the given address to be considered as
149 /// constant from this point onwards.
EmitDeclInvariant(CodeGenFunction & CGF,const VarDecl & D,llvm::Constant * Addr)150 static void EmitDeclInvariant(CodeGenFunction &CGF, const VarDecl &D,
151 llvm::Constant *Addr) {
152 return CGF.EmitInvariantStart(
153 Addr, CGF.getContext().getTypeSizeInChars(D.getType()));
154 }
155
EmitInvariantStart(llvm::Constant * Addr,CharUnits Size)156 void CodeGenFunction::EmitInvariantStart(llvm::Constant *Addr, CharUnits Size) {
157 // Do not emit the intrinsic if we're not optimizing.
158 if (!CGM.getCodeGenOpts().OptimizationLevel)
159 return;
160
161 // Grab the llvm.invariant.start intrinsic.
162 llvm::Intrinsic::ID InvStartID = llvm::Intrinsic::invariant_start;
163 // Overloaded address space type.
164 llvm::Type *ObjectPtr[1] = {Int8PtrTy};
165 llvm::Function *InvariantStart = CGM.getIntrinsic(InvStartID, ObjectPtr);
166
167 // Emit a call with the size in bytes of the object.
168 uint64_t Width = Size.getQuantity();
169 llvm::Value *Args[2] = { llvm::ConstantInt::getSigned(Int64Ty, Width),
170 llvm::ConstantExpr::getBitCast(Addr, Int8PtrTy)};
171 Builder.CreateCall(InvariantStart, Args);
172 }
173
EmitCXXGlobalVarDeclInit(const VarDecl & D,llvm::Constant * DeclPtr,bool PerformInit)174 void CodeGenFunction::EmitCXXGlobalVarDeclInit(const VarDecl &D,
175 llvm::Constant *DeclPtr,
176 bool PerformInit) {
177
178 const Expr *Init = D.getInit();
179 QualType T = D.getType();
180
181 // The address space of a static local variable (DeclPtr) may be different
182 // from the address space of the "this" argument of the constructor. In that
183 // case, we need an addrspacecast before calling the constructor.
184 //
185 // struct StructWithCtor {
186 // __device__ StructWithCtor() {...}
187 // };
188 // __device__ void foo() {
189 // __shared__ StructWithCtor s;
190 // ...
191 // }
192 //
193 // For example, in the above CUDA code, the static local variable s has a
194 // "shared" address space qualifier, but the constructor of StructWithCtor
195 // expects "this" in the "generic" address space.
196 unsigned ExpectedAddrSpace = getContext().getTargetAddressSpace(T);
197 unsigned ActualAddrSpace = DeclPtr->getType()->getPointerAddressSpace();
198 if (ActualAddrSpace != ExpectedAddrSpace) {
199 llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(T);
200 llvm::PointerType *PTy = llvm::PointerType::get(LTy, ExpectedAddrSpace);
201 DeclPtr = llvm::ConstantExpr::getAddrSpaceCast(DeclPtr, PTy);
202 }
203
204 ConstantAddress DeclAddr(DeclPtr, getContext().getDeclAlign(&D));
205
206 if (!T->isReferenceType()) {
207 if (getLangOpts().OpenMP && !getLangOpts().OpenMPSimd &&
208 D.hasAttr<OMPThreadPrivateDeclAttr>()) {
209 (void)CGM.getOpenMPRuntime().emitThreadPrivateVarDefinition(
210 &D, DeclAddr, D.getAttr<OMPThreadPrivateDeclAttr>()->getLocation(),
211 PerformInit, this);
212 }
213 if (PerformInit)
214 EmitDeclInit(*this, D, DeclAddr);
215 if (CGM.isTypeConstant(D.getType(), true))
216 EmitDeclInvariant(*this, D, DeclPtr);
217 else
218 EmitDeclDestroy(*this, D, DeclAddr);
219 return;
220 }
221
222 assert(PerformInit && "cannot have constant initializer which needs "
223 "destruction for reference");
224 RValue RV = EmitReferenceBindingToExpr(Init);
225 EmitStoreOfScalar(RV.getScalarVal(), DeclAddr, false, T);
226 }
227
228 /// Create a stub function, suitable for being passed to atexit,
229 /// which passes the given address to the given destructor function.
createAtExitStub(const VarDecl & VD,llvm::FunctionCallee dtor,llvm::Constant * addr)230 llvm::Function *CodeGenFunction::createAtExitStub(const VarDecl &VD,
231 llvm::FunctionCallee dtor,
232 llvm::Constant *addr) {
233 // Get the destructor function type, void(*)(void).
234 llvm::FunctionType *ty = llvm::FunctionType::get(CGM.VoidTy, false);
235 SmallString<256> FnName;
236 {
237 llvm::raw_svector_ostream Out(FnName);
238 CGM.getCXXABI().getMangleContext().mangleDynamicAtExitDestructor(&VD, Out);
239 }
240
241 const CGFunctionInfo &FI = CGM.getTypes().arrangeNullaryFunction();
242 llvm::Function *fn = CGM.CreateGlobalInitOrCleanUpFunction(
243 ty, FnName.str(), FI, VD.getLocation());
244
245 CodeGenFunction CGF(CGM);
246
247 CGF.StartFunction(GlobalDecl(&VD, DynamicInitKind::AtExit),
248 CGM.getContext().VoidTy, fn, FI, FunctionArgList(),
249 VD.getLocation(), VD.getInit()->getExprLoc());
250 // Emit an artificial location for this function.
251 auto AL = ApplyDebugLocation::CreateArtificial(CGF);
252
253 llvm::CallInst *call = CGF.Builder.CreateCall(dtor, addr);
254
255 // Make sure the call and the callee agree on calling convention.
256 if (auto *dtorFn = dyn_cast<llvm::Function>(
257 dtor.getCallee()->stripPointerCastsAndAliases()))
258 call->setCallingConv(dtorFn->getCallingConv());
259
260 CGF.FinishFunction();
261
262 return fn;
263 }
264
265 /// Register a global destructor using the C atexit runtime function.
registerGlobalDtorWithAtExit(const VarDecl & VD,llvm::FunctionCallee dtor,llvm::Constant * addr)266 void CodeGenFunction::registerGlobalDtorWithAtExit(const VarDecl &VD,
267 llvm::FunctionCallee dtor,
268 llvm::Constant *addr) {
269 // Create a function which calls the destructor.
270 llvm::Constant *dtorStub = createAtExitStub(VD, dtor, addr);
271 registerGlobalDtorWithAtExit(dtorStub);
272 }
273
registerGlobalDtorWithAtExit(llvm::Constant * dtorStub)274 void CodeGenFunction::registerGlobalDtorWithAtExit(llvm::Constant *dtorStub) {
275 // extern "C" int atexit(void (*f)(void));
276 assert(dtorStub->getType() ==
277 llvm::PointerType::get(
278 llvm::FunctionType::get(CGM.VoidTy, false),
279 dtorStub->getType()->getPointerAddressSpace()) &&
280 "Argument to atexit has a wrong type.");
281
282 llvm::FunctionType *atexitTy =
283 llvm::FunctionType::get(IntTy, dtorStub->getType(), false);
284
285 llvm::FunctionCallee atexit =
286 CGM.CreateRuntimeFunction(atexitTy, "atexit", llvm::AttributeList(),
287 /*Local=*/true);
288 if (llvm::Function *atexitFn = dyn_cast<llvm::Function>(atexit.getCallee()))
289 atexitFn->setDoesNotThrow();
290
291 EmitNounwindRuntimeCall(atexit, dtorStub);
292 }
293
294 llvm::Value *
unregisterGlobalDtorWithUnAtExit(llvm::Constant * dtorStub)295 CodeGenFunction::unregisterGlobalDtorWithUnAtExit(llvm::Constant *dtorStub) {
296 // The unatexit subroutine unregisters __dtor functions that were previously
297 // registered by the atexit subroutine. If the referenced function is found,
298 // it is removed from the list of functions that are called at normal program
299 // termination and the unatexit returns a value of 0, otherwise a non-zero
300 // value is returned.
301 //
302 // extern "C" int unatexit(void (*f)(void));
303 assert(dtorStub->getType() ==
304 llvm::PointerType::get(
305 llvm::FunctionType::get(CGM.VoidTy, false),
306 dtorStub->getType()->getPointerAddressSpace()) &&
307 "Argument to unatexit has a wrong type.");
308
309 llvm::FunctionType *unatexitTy =
310 llvm::FunctionType::get(IntTy, {dtorStub->getType()}, /*isVarArg=*/false);
311
312 llvm::FunctionCallee unatexit =
313 CGM.CreateRuntimeFunction(unatexitTy, "unatexit", llvm::AttributeList());
314
315 cast<llvm::Function>(unatexit.getCallee())->setDoesNotThrow();
316
317 return EmitNounwindRuntimeCall(unatexit, dtorStub);
318 }
319
EmitCXXGuardedInit(const VarDecl & D,llvm::GlobalVariable * DeclPtr,bool PerformInit)320 void CodeGenFunction::EmitCXXGuardedInit(const VarDecl &D,
321 llvm::GlobalVariable *DeclPtr,
322 bool PerformInit) {
323 // If we've been asked to forbid guard variables, emit an error now.
324 // This diagnostic is hard-coded for Darwin's use case; we can find
325 // better phrasing if someone else needs it.
326 if (CGM.getCodeGenOpts().ForbidGuardVariables)
327 CGM.Error(D.getLocation(),
328 "this initialization requires a guard variable, which "
329 "the kernel does not support");
330
331 CGM.getCXXABI().EmitGuardedInit(*this, D, DeclPtr, PerformInit);
332 }
333
EmitCXXGuardedInitBranch(llvm::Value * NeedsInit,llvm::BasicBlock * InitBlock,llvm::BasicBlock * NoInitBlock,GuardKind Kind,const VarDecl * D)334 void CodeGenFunction::EmitCXXGuardedInitBranch(llvm::Value *NeedsInit,
335 llvm::BasicBlock *InitBlock,
336 llvm::BasicBlock *NoInitBlock,
337 GuardKind Kind,
338 const VarDecl *D) {
339 assert((Kind == GuardKind::TlsGuard || D) && "no guarded variable");
340
341 // A guess at how many times we will enter the initialization of a
342 // variable, depending on the kind of variable.
343 static const uint64_t InitsPerTLSVar = 1024;
344 static const uint64_t InitsPerLocalVar = 1024 * 1024;
345
346 llvm::MDNode *Weights;
347 if (Kind == GuardKind::VariableGuard && !D->isLocalVarDecl()) {
348 // For non-local variables, don't apply any weighting for now. Due to our
349 // use of COMDATs, we expect there to be at most one initialization of the
350 // variable per DSO, but we have no way to know how many DSOs will try to
351 // initialize the variable.
352 Weights = nullptr;
353 } else {
354 uint64_t NumInits;
355 // FIXME: For the TLS case, collect and use profiling information to
356 // determine a more accurate brach weight.
357 if (Kind == GuardKind::TlsGuard || D->getTLSKind())
358 NumInits = InitsPerTLSVar;
359 else
360 NumInits = InitsPerLocalVar;
361
362 // The probability of us entering the initializer is
363 // 1 / (total number of times we attempt to initialize the variable).
364 llvm::MDBuilder MDHelper(CGM.getLLVMContext());
365 Weights = MDHelper.createBranchWeights(1, NumInits - 1);
366 }
367
368 Builder.CreateCondBr(NeedsInit, InitBlock, NoInitBlock, Weights);
369 }
370
CreateGlobalInitOrCleanUpFunction(llvm::FunctionType * FTy,const Twine & Name,const CGFunctionInfo & FI,SourceLocation Loc,bool TLS)371 llvm::Function *CodeGenModule::CreateGlobalInitOrCleanUpFunction(
372 llvm::FunctionType *FTy, const Twine &Name, const CGFunctionInfo &FI,
373 SourceLocation Loc, bool TLS) {
374 llvm::Function *Fn = llvm::Function::Create(
375 FTy, llvm::GlobalValue::InternalLinkage, Name, &getModule());
376
377 if (!getLangOpts().AppleKext && !TLS) {
378 // Set the section if needed.
379 if (const char *Section = getTarget().getStaticInitSectionSpecifier())
380 Fn->setSection(Section);
381 }
382
383 SetInternalFunctionAttributes(GlobalDecl(), Fn, FI);
384
385 Fn->setCallingConv(getRuntimeCC());
386
387 if (!getLangOpts().Exceptions)
388 Fn->setDoesNotThrow();
389
390 if (getLangOpts().Sanitize.has(SanitizerKind::Address) &&
391 !isInSanitizerBlacklist(SanitizerKind::Address, Fn, Loc))
392 Fn->addFnAttr(llvm::Attribute::SanitizeAddress);
393
394 if (getLangOpts().Sanitize.has(SanitizerKind::KernelAddress) &&
395 !isInSanitizerBlacklist(SanitizerKind::KernelAddress, Fn, Loc))
396 Fn->addFnAttr(llvm::Attribute::SanitizeAddress);
397
398 if (getLangOpts().Sanitize.has(SanitizerKind::HWAddress) &&
399 !isInSanitizerBlacklist(SanitizerKind::HWAddress, Fn, Loc))
400 Fn->addFnAttr(llvm::Attribute::SanitizeHWAddress);
401
402 if (getLangOpts().Sanitize.has(SanitizerKind::KernelHWAddress) &&
403 !isInSanitizerBlacklist(SanitizerKind::KernelHWAddress, Fn, Loc))
404 Fn->addFnAttr(llvm::Attribute::SanitizeHWAddress);
405
406 if (getLangOpts().Sanitize.has(SanitizerKind::MemTag) &&
407 !isInSanitizerBlacklist(SanitizerKind::MemTag, Fn, Loc))
408 Fn->addFnAttr(llvm::Attribute::SanitizeMemTag);
409
410 if (getLangOpts().Sanitize.has(SanitizerKind::Thread) &&
411 !isInSanitizerBlacklist(SanitizerKind::Thread, Fn, Loc))
412 Fn->addFnAttr(llvm::Attribute::SanitizeThread);
413
414 if (getLangOpts().Sanitize.has(SanitizerKind::Memory) &&
415 !isInSanitizerBlacklist(SanitizerKind::Memory, Fn, Loc))
416 Fn->addFnAttr(llvm::Attribute::SanitizeMemory);
417
418 if (getLangOpts().Sanitize.has(SanitizerKind::KernelMemory) &&
419 !isInSanitizerBlacklist(SanitizerKind::KernelMemory, Fn, Loc))
420 Fn->addFnAttr(llvm::Attribute::SanitizeMemory);
421
422 if (getLangOpts().Sanitize.has(SanitizerKind::SafeStack) &&
423 !isInSanitizerBlacklist(SanitizerKind::SafeStack, Fn, Loc))
424 Fn->addFnAttr(llvm::Attribute::SafeStack);
425
426 if (getLangOpts().Sanitize.has(SanitizerKind::ShadowCallStack) &&
427 !isInSanitizerBlacklist(SanitizerKind::ShadowCallStack, Fn, Loc))
428 Fn->addFnAttr(llvm::Attribute::ShadowCallStack);
429
430 return Fn;
431 }
432
433 /// Create a global pointer to a function that will initialize a global
434 /// variable. The user has requested that this pointer be emitted in a specific
435 /// section.
EmitPointerToInitFunc(const VarDecl * D,llvm::GlobalVariable * GV,llvm::Function * InitFunc,InitSegAttr * ISA)436 void CodeGenModule::EmitPointerToInitFunc(const VarDecl *D,
437 llvm::GlobalVariable *GV,
438 llvm::Function *InitFunc,
439 InitSegAttr *ISA) {
440 llvm::GlobalVariable *PtrArray = new llvm::GlobalVariable(
441 TheModule, InitFunc->getType(), /*isConstant=*/true,
442 llvm::GlobalValue::PrivateLinkage, InitFunc, "__cxx_init_fn_ptr");
443 PtrArray->setSection(ISA->getSection());
444 addUsedGlobal(PtrArray);
445
446 // If the GV is already in a comdat group, then we have to join it.
447 if (llvm::Comdat *C = GV->getComdat())
448 PtrArray->setComdat(C);
449 }
450
451 void
EmitCXXGlobalVarDeclInitFunc(const VarDecl * D,llvm::GlobalVariable * Addr,bool PerformInit)452 CodeGenModule::EmitCXXGlobalVarDeclInitFunc(const VarDecl *D,
453 llvm::GlobalVariable *Addr,
454 bool PerformInit) {
455
456 // According to E.2.3.1 in CUDA-7.5 Programming guide: __device__,
457 // __constant__ and __shared__ variables defined in namespace scope,
458 // that are of class type, cannot have a non-empty constructor. All
459 // the checks have been done in Sema by now. Whatever initializers
460 // are allowed are empty and we just need to ignore them here.
461 if (getLangOpts().CUDAIsDevice && !getLangOpts().GPUAllowDeviceInit &&
462 (D->hasAttr<CUDADeviceAttr>() || D->hasAttr<CUDAConstantAttr>() ||
463 D->hasAttr<CUDASharedAttr>()))
464 return;
465
466 if (getLangOpts().OpenMP &&
467 getOpenMPRuntime().emitDeclareTargetVarDefinition(D, Addr, PerformInit))
468 return;
469
470 // Check if we've already initialized this decl.
471 auto I = DelayedCXXInitPosition.find(D);
472 if (I != DelayedCXXInitPosition.end() && I->second == ~0U)
473 return;
474
475 llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
476 SmallString<256> FnName;
477 {
478 llvm::raw_svector_ostream Out(FnName);
479 getCXXABI().getMangleContext().mangleDynamicInitializer(D, Out);
480 }
481
482 // Create a variable initialization function.
483 llvm::Function *Fn = CreateGlobalInitOrCleanUpFunction(
484 FTy, FnName.str(), getTypes().arrangeNullaryFunction(), D->getLocation());
485
486 auto *ISA = D->getAttr<InitSegAttr>();
487 CodeGenFunction(*this).GenerateCXXGlobalVarDeclInitFunc(Fn, D, Addr,
488 PerformInit);
489
490 llvm::GlobalVariable *COMDATKey =
491 supportsCOMDAT() && D->isExternallyVisible() ? Addr : nullptr;
492
493 if (D->getTLSKind()) {
494 // FIXME: Should we support init_priority for thread_local?
495 // FIXME: We only need to register one __cxa_thread_atexit function for the
496 // entire TU.
497 CXXThreadLocalInits.push_back(Fn);
498 CXXThreadLocalInitVars.push_back(D);
499 } else if (PerformInit && ISA) {
500 EmitPointerToInitFunc(D, Addr, Fn, ISA);
501 } else if (auto *IPA = D->getAttr<InitPriorityAttr>()) {
502 OrderGlobalInits Key(IPA->getPriority(), PrioritizedCXXGlobalInits.size());
503 PrioritizedCXXGlobalInits.push_back(std::make_pair(Key, Fn));
504 } else if (isTemplateInstantiation(D->getTemplateSpecializationKind()) ||
505 getContext().GetGVALinkageForVariable(D) == GVA_DiscardableODR) {
506 // C++ [basic.start.init]p2:
507 // Definitions of explicitly specialized class template static data
508 // members have ordered initialization. Other class template static data
509 // members (i.e., implicitly or explicitly instantiated specializations)
510 // have unordered initialization.
511 //
512 // As a consequence, we can put them into their own llvm.global_ctors entry.
513 //
514 // If the global is externally visible, put the initializer into a COMDAT
515 // group with the global being initialized. On most platforms, this is a
516 // minor startup time optimization. In the MS C++ ABI, there are no guard
517 // variables, so this COMDAT key is required for correctness.
518 AddGlobalCtor(Fn, 65535, COMDATKey);
519 if (getTarget().getCXXABI().isMicrosoft() && COMDATKey) {
520 // In The MS C++, MS add template static data member in the linker
521 // drective.
522 addUsedGlobal(COMDATKey);
523 }
524 } else if (D->hasAttr<SelectAnyAttr>()) {
525 // SelectAny globals will be comdat-folded. Put the initializer into a
526 // COMDAT group associated with the global, so the initializers get folded
527 // too.
528 AddGlobalCtor(Fn, 65535, COMDATKey);
529 } else {
530 I = DelayedCXXInitPosition.find(D); // Re-do lookup in case of re-hash.
531 if (I == DelayedCXXInitPosition.end()) {
532 CXXGlobalInits.push_back(Fn);
533 } else if (I->second != ~0U) {
534 assert(I->second < CXXGlobalInits.size() &&
535 CXXGlobalInits[I->second] == nullptr);
536 CXXGlobalInits[I->second] = Fn;
537 }
538 }
539
540 // Remember that we already emitted the initializer for this global.
541 DelayedCXXInitPosition[D] = ~0U;
542 }
543
EmitCXXThreadLocalInitFunc()544 void CodeGenModule::EmitCXXThreadLocalInitFunc() {
545 getCXXABI().EmitThreadLocalInitFuncs(
546 *this, CXXThreadLocals, CXXThreadLocalInits, CXXThreadLocalInitVars);
547
548 CXXThreadLocalInits.clear();
549 CXXThreadLocalInitVars.clear();
550 CXXThreadLocals.clear();
551 }
552
getTransformedFileName(llvm::Module & M)553 static SmallString<128> getTransformedFileName(llvm::Module &M) {
554 SmallString<128> FileName = llvm::sys::path::filename(M.getName());
555
556 if (FileName.empty())
557 FileName = "<null>";
558
559 for (size_t i = 0; i < FileName.size(); ++i) {
560 // Replace everything that's not [a-zA-Z0-9._] with a _. This set happens
561 // to be the set of C preprocessing numbers.
562 if (!isPreprocessingNumberBody(FileName[i]))
563 FileName[i] = '_';
564 }
565
566 return FileName;
567 }
568
569 void
EmitCXXGlobalInitFunc()570 CodeGenModule::EmitCXXGlobalInitFunc() {
571 while (!CXXGlobalInits.empty() && !CXXGlobalInits.back())
572 CXXGlobalInits.pop_back();
573
574 if (CXXGlobalInits.empty() && PrioritizedCXXGlobalInits.empty())
575 return;
576
577 llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
578 const CGFunctionInfo &FI = getTypes().arrangeNullaryFunction();
579
580 const bool UseSinitAndSterm = getCXXABI().useSinitAndSterm();
581 // Create our global prioritized initialization function.
582 if (!PrioritizedCXXGlobalInits.empty()) {
583 assert(!UseSinitAndSterm && "Prioritized sinit and sterm functions are not"
584 " supported yet.");
585
586 SmallVector<llvm::Function *, 8> LocalCXXGlobalInits;
587 llvm::array_pod_sort(PrioritizedCXXGlobalInits.begin(),
588 PrioritizedCXXGlobalInits.end());
589 // Iterate over "chunks" of ctors with same priority and emit each chunk
590 // into separate function. Note - everything is sorted first by priority,
591 // second - by lex order, so we emit ctor functions in proper order.
592 for (SmallVectorImpl<GlobalInitData >::iterator
593 I = PrioritizedCXXGlobalInits.begin(),
594 E = PrioritizedCXXGlobalInits.end(); I != E; ) {
595 SmallVectorImpl<GlobalInitData >::iterator
596 PrioE = std::upper_bound(I + 1, E, *I, GlobalInitPriorityCmp());
597
598 LocalCXXGlobalInits.clear();
599 unsigned Priority = I->first.priority;
600 // Compute the function suffix from priority. Prepend with zeroes to make
601 // sure the function names are also ordered as priorities.
602 std::string PrioritySuffix = llvm::utostr(Priority);
603 // Priority is always <= 65535 (enforced by sema).
604 PrioritySuffix = std::string(6-PrioritySuffix.size(), '0')+PrioritySuffix;
605 llvm::Function *Fn = CreateGlobalInitOrCleanUpFunction(
606 FTy, "_GLOBAL__I_" + PrioritySuffix, FI);
607
608 for (; I < PrioE; ++I)
609 LocalCXXGlobalInits.push_back(I->second);
610
611 CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn, LocalCXXGlobalInits);
612 AddGlobalCtor(Fn, Priority);
613 }
614 PrioritizedCXXGlobalInits.clear();
615 }
616
617 if (UseSinitAndSterm && CXXGlobalInits.empty())
618 return;
619
620 // Include the filename in the symbol name. Including "sub_" matches gcc
621 // and makes sure these symbols appear lexicographically behind the symbols
622 // with priority emitted above.
623 llvm::Function *Fn = CreateGlobalInitOrCleanUpFunction(
624 FTy, llvm::Twine("_GLOBAL__sub_I_", getTransformedFileName(getModule())),
625 FI);
626
627 CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn, CXXGlobalInits);
628 AddGlobalCtor(Fn);
629
630 // In OpenCL global init functions must be converted to kernels in order to
631 // be able to launch them from the host.
632 // FIXME: Some more work might be needed to handle destructors correctly.
633 // Current initialization function makes use of function pointers callbacks.
634 // We can't support function pointers especially between host and device.
635 // However it seems global destruction has little meaning without any
636 // dynamic resource allocation on the device and program scope variables are
637 // destroyed by the runtime when program is released.
638 if (getLangOpts().OpenCL) {
639 GenOpenCLArgMetadata(Fn);
640 Fn->setCallingConv(llvm::CallingConv::SPIR_KERNEL);
641 }
642
643 if (getLangOpts().HIP) {
644 Fn->setCallingConv(llvm::CallingConv::AMDGPU_KERNEL);
645 Fn->addFnAttr("device-init");
646 }
647
648 CXXGlobalInits.clear();
649 }
650
EmitCXXGlobalCleanUpFunc()651 void CodeGenModule::EmitCXXGlobalCleanUpFunc() {
652 if (CXXGlobalDtorsOrStermFinalizers.empty())
653 return;
654
655 llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
656 const CGFunctionInfo &FI = getTypes().arrangeNullaryFunction();
657
658 // Create our global cleanup function.
659 llvm::Function *Fn =
660 CreateGlobalInitOrCleanUpFunction(FTy, "_GLOBAL__D_a", FI);
661
662 CodeGenFunction(*this).GenerateCXXGlobalCleanUpFunc(
663 Fn, CXXGlobalDtorsOrStermFinalizers);
664 AddGlobalDtor(Fn);
665 CXXGlobalDtorsOrStermFinalizers.clear();
666 }
667
668 /// Emit the code necessary to initialize the given global variable.
GenerateCXXGlobalVarDeclInitFunc(llvm::Function * Fn,const VarDecl * D,llvm::GlobalVariable * Addr,bool PerformInit)669 void CodeGenFunction::GenerateCXXGlobalVarDeclInitFunc(llvm::Function *Fn,
670 const VarDecl *D,
671 llvm::GlobalVariable *Addr,
672 bool PerformInit) {
673 // Check if we need to emit debug info for variable initializer.
674 if (D->hasAttr<NoDebugAttr>())
675 DebugInfo = nullptr; // disable debug info indefinitely for this function
676
677 CurEHLocation = D->getBeginLoc();
678
679 StartFunction(GlobalDecl(D, DynamicInitKind::Initializer),
680 getContext().VoidTy, Fn, getTypes().arrangeNullaryFunction(),
681 FunctionArgList());
682 // Emit an artificial location for this function.
683 auto AL = ApplyDebugLocation::CreateArtificial(*this);
684
685 // Use guarded initialization if the global variable is weak. This
686 // occurs for, e.g., instantiated static data members and
687 // definitions explicitly marked weak.
688 //
689 // Also use guarded initialization for a variable with dynamic TLS and
690 // unordered initialization. (If the initialization is ordered, the ABI
691 // layer will guard the whole-TU initialization for us.)
692 if (Addr->hasWeakLinkage() || Addr->hasLinkOnceLinkage() ||
693 (D->getTLSKind() == VarDecl::TLS_Dynamic &&
694 isTemplateInstantiation(D->getTemplateSpecializationKind()))) {
695 EmitCXXGuardedInit(*D, Addr, PerformInit);
696 } else {
697 EmitCXXGlobalVarDeclInit(*D, Addr, PerformInit);
698 }
699
700 FinishFunction();
701 }
702
703 void
GenerateCXXGlobalInitFunc(llvm::Function * Fn,ArrayRef<llvm::Function * > Decls,ConstantAddress Guard)704 CodeGenFunction::GenerateCXXGlobalInitFunc(llvm::Function *Fn,
705 ArrayRef<llvm::Function *> Decls,
706 ConstantAddress Guard) {
707 {
708 auto NL = ApplyDebugLocation::CreateEmpty(*this);
709 StartFunction(GlobalDecl(), getContext().VoidTy, Fn,
710 getTypes().arrangeNullaryFunction(), FunctionArgList());
711 // Emit an artificial location for this function.
712 auto AL = ApplyDebugLocation::CreateArtificial(*this);
713
714 llvm::BasicBlock *ExitBlock = nullptr;
715 if (Guard.isValid()) {
716 // If we have a guard variable, check whether we've already performed
717 // these initializations. This happens for TLS initialization functions.
718 llvm::Value *GuardVal = Builder.CreateLoad(Guard);
719 llvm::Value *Uninit = Builder.CreateIsNull(GuardVal,
720 "guard.uninitialized");
721 llvm::BasicBlock *InitBlock = createBasicBlock("init");
722 ExitBlock = createBasicBlock("exit");
723 EmitCXXGuardedInitBranch(Uninit, InitBlock, ExitBlock,
724 GuardKind::TlsGuard, nullptr);
725 EmitBlock(InitBlock);
726 // Mark as initialized before initializing anything else. If the
727 // initializers use previously-initialized thread_local vars, that's
728 // probably supposed to be OK, but the standard doesn't say.
729 Builder.CreateStore(llvm::ConstantInt::get(GuardVal->getType(),1), Guard);
730
731 // The guard variable can't ever change again.
732 EmitInvariantStart(
733 Guard.getPointer(),
734 CharUnits::fromQuantity(
735 CGM.getDataLayout().getTypeAllocSize(GuardVal->getType())));
736 }
737
738 RunCleanupsScope Scope(*this);
739
740 // When building in Objective-C++ ARC mode, create an autorelease pool
741 // around the global initializers.
742 if (getLangOpts().ObjCAutoRefCount && getLangOpts().CPlusPlus) {
743 llvm::Value *token = EmitObjCAutoreleasePoolPush();
744 EmitObjCAutoreleasePoolCleanup(token);
745 }
746
747 for (unsigned i = 0, e = Decls.size(); i != e; ++i)
748 if (Decls[i])
749 EmitRuntimeCall(Decls[i]);
750
751 Scope.ForceCleanup();
752
753 if (ExitBlock) {
754 Builder.CreateBr(ExitBlock);
755 EmitBlock(ExitBlock);
756 }
757 }
758
759 FinishFunction();
760 }
761
GenerateCXXGlobalCleanUpFunc(llvm::Function * Fn,const std::vector<std::tuple<llvm::FunctionType *,llvm::WeakTrackingVH,llvm::Constant * >> & DtorsOrStermFinalizers)762 void CodeGenFunction::GenerateCXXGlobalCleanUpFunc(
763 llvm::Function *Fn,
764 const std::vector<std::tuple<llvm::FunctionType *, llvm::WeakTrackingVH,
765 llvm::Constant *>> &DtorsOrStermFinalizers) {
766 {
767 auto NL = ApplyDebugLocation::CreateEmpty(*this);
768 StartFunction(GlobalDecl(), getContext().VoidTy, Fn,
769 getTypes().arrangeNullaryFunction(), FunctionArgList());
770 // Emit an artificial location for this function.
771 auto AL = ApplyDebugLocation::CreateArtificial(*this);
772
773 // Emit the cleanups, in reverse order from construction.
774 for (unsigned i = 0, e = DtorsOrStermFinalizers.size(); i != e; ++i) {
775 llvm::FunctionType *CalleeTy;
776 llvm::Value *Callee;
777 llvm::Constant *Arg;
778 std::tie(CalleeTy, Callee, Arg) = DtorsOrStermFinalizers[e - i - 1];
779
780 llvm::CallInst *CI = nullptr;
781 if (Arg == nullptr) {
782 assert(
783 CGM.getCXXABI().useSinitAndSterm() &&
784 "Arg could not be nullptr unless using sinit and sterm functions.");
785 CI = Builder.CreateCall(CalleeTy, Callee);
786 } else
787 CI = Builder.CreateCall(CalleeTy, Callee, Arg);
788
789 // Make sure the call and the callee agree on calling convention.
790 if (llvm::Function *F = dyn_cast<llvm::Function>(Callee))
791 CI->setCallingConv(F->getCallingConv());
792 }
793 }
794
795 FinishFunction();
796 }
797
798 /// generateDestroyHelper - Generates a helper function which, when
799 /// invoked, destroys the given object. The address of the object
800 /// should be in global memory.
generateDestroyHelper(Address addr,QualType type,Destroyer * destroyer,bool useEHCleanupForArray,const VarDecl * VD)801 llvm::Function *CodeGenFunction::generateDestroyHelper(
802 Address addr, QualType type, Destroyer *destroyer,
803 bool useEHCleanupForArray, const VarDecl *VD) {
804 FunctionArgList args;
805 ImplicitParamDecl Dst(getContext(), getContext().VoidPtrTy,
806 ImplicitParamDecl::Other);
807 args.push_back(&Dst);
808
809 const CGFunctionInfo &FI =
810 CGM.getTypes().arrangeBuiltinFunctionDeclaration(getContext().VoidTy, args);
811 llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(FI);
812 llvm::Function *fn = CGM.CreateGlobalInitOrCleanUpFunction(
813 FTy, "__cxx_global_array_dtor", FI, VD->getLocation());
814
815 CurEHLocation = VD->getBeginLoc();
816
817 StartFunction(GlobalDecl(VD, DynamicInitKind::GlobalArrayDestructor),
818 getContext().VoidTy, fn, FI, args);
819 // Emit an artificial location for this function.
820 auto AL = ApplyDebugLocation::CreateArtificial(*this);
821
822 emitDestroy(addr, type, destroyer, useEHCleanupForArray);
823
824 FinishFunction();
825
826 return fn;
827 }
828