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