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 "CodeGenFunction.h" 14 #include "CGCXXABI.h" 15 #include "CGObjCRuntime.h" 16 #include "CGOpenMPRuntime.h" 17 #include "TargetInfo.h" 18 #include "clang/Basic/CodeGenOptions.h" 19 #include "llvm/ADT/StringExtras.h" 20 #include "llvm/IR/Intrinsics.h" 21 #include "llvm/IR/MDBuilder.h" 22 #include "llvm/Support/Path.h" 23 24 using namespace clang; 25 using namespace CodeGen; 26 27 static void EmitDeclInit(CodeGenFunction &CGF, const VarDecl &D, 28 ConstantAddress DeclPtr) { 29 assert( 30 (D.hasGlobalStorage() || 31 (D.hasLocalStorage() && CGF.getContext().getLangOpts().OpenCLCPlusPlus)) && 32 "VarDecl must have global or local (in the case of OpenCL) storage!"); 33 assert(!D.getType()->isReferenceType() && 34 "Should not call EmitDeclInit on a reference!"); 35 36 QualType type = D.getType(); 37 LValue lv = CGF.MakeAddrLValue(DeclPtr, type); 38 39 const Expr *Init = D.getInit(); 40 switch (CGF.getEvaluationKind(type)) { 41 case TEK_Scalar: { 42 CodeGenModule &CGM = CGF.CGM; 43 if (lv.isObjCStrong()) 44 CGM.getObjCRuntime().EmitObjCGlobalAssign(CGF, CGF.EmitScalarExpr(Init), 45 DeclPtr, D.getTLSKind()); 46 else if (lv.isObjCWeak()) 47 CGM.getObjCRuntime().EmitObjCWeakAssign(CGF, CGF.EmitScalarExpr(Init), 48 DeclPtr); 49 else 50 CGF.EmitScalarInit(Init, &D, lv, false); 51 return; 52 } 53 case TEK_Complex: 54 CGF.EmitComplexExprIntoLValue(Init, lv, /*isInit*/ true); 55 return; 56 case TEK_Aggregate: 57 CGF.EmitAggExpr(Init, AggValueSlot::forLValue(lv,AggValueSlot::IsDestructed, 58 AggValueSlot::DoesNotNeedGCBarriers, 59 AggValueSlot::IsNotAliased, 60 AggValueSlot::DoesNotOverlap)); 61 return; 62 } 63 llvm_unreachable("bad evaluation kind"); 64 } 65 66 /// Emit code to cause the destruction of the given variable with 67 /// static storage duration. 68 static void EmitDeclDestroy(CodeGenFunction &CGF, const VarDecl &D, 69 ConstantAddress Addr) { 70 // Honor __attribute__((no_destroy)) and bail instead of attempting 71 // to emit a reference to a possibly nonexistent destructor, which 72 // in turn can cause a crash. This will result in a global constructor 73 // that isn't balanced out by a destructor call as intended by the 74 // attribute. This also checks for -fno-c++-static-destructors and 75 // bails even if the attribute is not present. 76 if (D.isNoDestroy(CGF.getContext())) 77 return; 78 79 CodeGenModule &CGM = CGF.CGM; 80 81 // FIXME: __attribute__((cleanup)) ? 82 83 QualType Type = D.getType(); 84 QualType::DestructionKind DtorKind = Type.isDestructedType(); 85 86 switch (DtorKind) { 87 case QualType::DK_none: 88 return; 89 90 case QualType::DK_cxx_destructor: 91 break; 92 93 case QualType::DK_objc_strong_lifetime: 94 case QualType::DK_objc_weak_lifetime: 95 case QualType::DK_nontrivial_c_struct: 96 // We don't care about releasing objects during process teardown. 97 assert(!D.getTLSKind() && "should have rejected this"); 98 return; 99 } 100 101 llvm::FunctionCallee Func; 102 llvm::Constant *Argument; 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 Func = CodeGenFunction(CGM) 141 .generateDestroyHelper(Addr, Type, CGF.getDestroyer(DtorKind), 142 CGF.needsEHCleanup(DtorKind), &D); 143 Argument = llvm::Constant::getNullValue(CGF.Int8PtrTy); 144 } 145 146 CGM.getCXXABI().registerGlobalDtor(CGF, D, Func, Argument); 147 } 148 149 /// Emit code to cause the variable at the given address to be considered as 150 /// constant from this point onwards. 151 static void EmitDeclInvariant(CodeGenFunction &CGF, const VarDecl &D, 152 llvm::Constant *Addr) { 153 return CGF.EmitInvariantStart( 154 Addr, CGF.getContext().getTypeSizeInChars(D.getType())); 155 } 156 157 void CodeGenFunction::EmitInvariantStart(llvm::Constant *Addr, CharUnits Size) { 158 // Do not emit the intrinsic if we're not optimizing. 159 if (!CGM.getCodeGenOpts().OptimizationLevel) 160 return; 161 162 // Grab the llvm.invariant.start intrinsic. 163 llvm::Intrinsic::ID InvStartID = llvm::Intrinsic::invariant_start; 164 // Overloaded address space type. 165 llvm::Type *ObjectPtr[1] = {Int8PtrTy}; 166 llvm::Function *InvariantStart = CGM.getIntrinsic(InvStartID, ObjectPtr); 167 168 // Emit a call with the size in bytes of the object. 169 uint64_t Width = Size.getQuantity(); 170 llvm::Value *Args[2] = { llvm::ConstantInt::getSigned(Int64Ty, Width), 171 llvm::ConstantExpr::getBitCast(Addr, Int8PtrTy)}; 172 Builder.CreateCall(InvariantStart, Args); 173 } 174 175 void CodeGenFunction::EmitCXXGlobalVarDeclInit(const VarDecl &D, 176 llvm::Constant *DeclPtr, 177 bool PerformInit) { 178 179 const Expr *Init = D.getInit(); 180 QualType T = D.getType(); 181 182 // The address space of a static local variable (DeclPtr) may be different 183 // from the address space of the "this" argument of the constructor. In that 184 // case, we need an addrspacecast before calling the constructor. 185 // 186 // struct StructWithCtor { 187 // __device__ StructWithCtor() {...} 188 // }; 189 // __device__ void foo() { 190 // __shared__ StructWithCtor s; 191 // ... 192 // } 193 // 194 // For example, in the above CUDA code, the static local variable s has a 195 // "shared" address space qualifier, but the constructor of StructWithCtor 196 // expects "this" in the "generic" address space. 197 unsigned ExpectedAddrSpace = getContext().getTargetAddressSpace(T); 198 unsigned ActualAddrSpace = DeclPtr->getType()->getPointerAddressSpace(); 199 if (ActualAddrSpace != ExpectedAddrSpace) { 200 llvm::Type *LTy = CGM.getTypes().ConvertTypeForMem(T); 201 llvm::PointerType *PTy = llvm::PointerType::get(LTy, ExpectedAddrSpace); 202 DeclPtr = llvm::ConstantExpr::getAddrSpaceCast(DeclPtr, PTy); 203 } 204 205 ConstantAddress DeclAddr(DeclPtr, getContext().getDeclAlign(&D)); 206 207 if (!T->isReferenceType()) { 208 if (getLangOpts().OpenMP && !getLangOpts().OpenMPSimd && 209 D.hasAttr<OMPThreadPrivateDeclAttr>()) { 210 (void)CGM.getOpenMPRuntime().emitThreadPrivateVarDefinition( 211 &D, DeclAddr, D.getAttr<OMPThreadPrivateDeclAttr>()->getLocation(), 212 PerformInit, this); 213 } 214 if (PerformInit) 215 EmitDeclInit(*this, D, DeclAddr); 216 if (CGM.isTypeConstant(D.getType(), true)) 217 EmitDeclInvariant(*this, D, DeclPtr); 218 else 219 EmitDeclDestroy(*this, D, DeclAddr); 220 return; 221 } 222 223 assert(PerformInit && "cannot have constant initializer which needs " 224 "destruction for reference"); 225 RValue RV = EmitReferenceBindingToExpr(Init); 226 EmitStoreOfScalar(RV.getScalarVal(), DeclAddr, false, T); 227 } 228 229 /// Create a stub function, suitable for being passed to atexit, 230 /// which passes the given address to the given destructor function. 231 llvm::Function *CodeGenFunction::createAtExitStub(const VarDecl &VD, 232 llvm::FunctionCallee dtor, 233 llvm::Constant *addr) { 234 // Get the destructor function type, void(*)(void). 235 llvm::FunctionType *ty = llvm::FunctionType::get(CGM.VoidTy, false); 236 SmallString<256> FnName; 237 { 238 llvm::raw_svector_ostream Out(FnName); 239 CGM.getCXXABI().getMangleContext().mangleDynamicAtExitDestructor(&VD, Out); 240 } 241 242 const CGFunctionInfo &FI = CGM.getTypes().arrangeNullaryFunction(); 243 llvm::Function *fn = CGM.CreateGlobalInitOrDestructFunction( 244 ty, FnName.str(), FI, VD.getLocation()); 245 246 CodeGenFunction CGF(CGM); 247 248 CGF.StartFunction(GlobalDecl(&VD, DynamicInitKind::AtExit), 249 CGM.getContext().VoidTy, fn, FI, FunctionArgList()); 250 251 llvm::CallInst *call = CGF.Builder.CreateCall(dtor, addr); 252 253 // Make sure the call and the callee agree on calling convention. 254 if (llvm::Function *dtorFn = 255 dyn_cast<llvm::Function>(dtor.getCallee()->stripPointerCasts())) 256 call->setCallingConv(dtorFn->getCallingConv()); 257 258 CGF.FinishFunction(); 259 260 return fn; 261 } 262 263 /// Register a global destructor using the C atexit runtime function. 264 void CodeGenFunction::registerGlobalDtorWithAtExit(const VarDecl &VD, 265 llvm::FunctionCallee dtor, 266 llvm::Constant *addr) { 267 // Create a function which calls the destructor. 268 llvm::Constant *dtorStub = createAtExitStub(VD, dtor, addr); 269 registerGlobalDtorWithAtExit(dtorStub); 270 } 271 272 void CodeGenFunction::registerGlobalDtorWithAtExit(llvm::Constant *dtorStub) { 273 // extern "C" int atexit(void (*f)(void)); 274 llvm::FunctionType *atexitTy = 275 llvm::FunctionType::get(IntTy, dtorStub->getType(), false); 276 277 llvm::FunctionCallee atexit = 278 CGM.CreateRuntimeFunction(atexitTy, "atexit", llvm::AttributeList(), 279 /*Local=*/true); 280 if (llvm::Function *atexitFn = dyn_cast<llvm::Function>(atexit.getCallee())) 281 atexitFn->setDoesNotThrow(); 282 283 EmitNounwindRuntimeCall(atexit, dtorStub); 284 } 285 286 void CodeGenFunction::EmitCXXGuardedInit(const VarDecl &D, 287 llvm::GlobalVariable *DeclPtr, 288 bool PerformInit) { 289 // If we've been asked to forbid guard variables, emit an error now. 290 // This diagnostic is hard-coded for Darwin's use case; we can find 291 // better phrasing if someone else needs it. 292 if (CGM.getCodeGenOpts().ForbidGuardVariables) 293 CGM.Error(D.getLocation(), 294 "this initialization requires a guard variable, which " 295 "the kernel does not support"); 296 297 CGM.getCXXABI().EmitGuardedInit(*this, D, DeclPtr, PerformInit); 298 } 299 300 void CodeGenFunction::EmitCXXGuardedInitBranch(llvm::Value *NeedsInit, 301 llvm::BasicBlock *InitBlock, 302 llvm::BasicBlock *NoInitBlock, 303 GuardKind Kind, 304 const VarDecl *D) { 305 assert((Kind == GuardKind::TlsGuard || D) && "no guarded variable"); 306 307 // A guess at how many times we will enter the initialization of a 308 // variable, depending on the kind of variable. 309 static const uint64_t InitsPerTLSVar = 1024; 310 static const uint64_t InitsPerLocalVar = 1024 * 1024; 311 312 llvm::MDNode *Weights; 313 if (Kind == GuardKind::VariableGuard && !D->isLocalVarDecl()) { 314 // For non-local variables, don't apply any weighting for now. Due to our 315 // use of COMDATs, we expect there to be at most one initialization of the 316 // variable per DSO, but we have no way to know how many DSOs will try to 317 // initialize the variable. 318 Weights = nullptr; 319 } else { 320 uint64_t NumInits; 321 // FIXME: For the TLS case, collect and use profiling information to 322 // determine a more accurate brach weight. 323 if (Kind == GuardKind::TlsGuard || D->getTLSKind()) 324 NumInits = InitsPerTLSVar; 325 else 326 NumInits = InitsPerLocalVar; 327 328 // The probability of us entering the initializer is 329 // 1 / (total number of times we attempt to initialize the variable). 330 llvm::MDBuilder MDHelper(CGM.getLLVMContext()); 331 Weights = MDHelper.createBranchWeights(1, NumInits - 1); 332 } 333 334 Builder.CreateCondBr(NeedsInit, InitBlock, NoInitBlock, Weights); 335 } 336 337 llvm::Function *CodeGenModule::CreateGlobalInitOrDestructFunction( 338 llvm::FunctionType *FTy, const Twine &Name, const CGFunctionInfo &FI, 339 SourceLocation Loc, bool TLS) { 340 llvm::Function *Fn = 341 llvm::Function::Create(FTy, llvm::GlobalValue::InternalLinkage, 342 Name, &getModule()); 343 if (!getLangOpts().AppleKext && !TLS) { 344 // Set the section if needed. 345 if (const char *Section = getTarget().getStaticInitSectionSpecifier()) 346 Fn->setSection(Section); 347 } 348 349 SetInternalFunctionAttributes(GlobalDecl(), Fn, FI); 350 351 Fn->setCallingConv(getRuntimeCC()); 352 353 if (!getLangOpts().Exceptions) 354 Fn->setDoesNotThrow(); 355 356 if (getLangOpts().Sanitize.has(SanitizerKind::Address) && 357 !isInSanitizerBlacklist(SanitizerKind::Address, Fn, Loc)) 358 Fn->addFnAttr(llvm::Attribute::SanitizeAddress); 359 360 if (getLangOpts().Sanitize.has(SanitizerKind::KernelAddress) && 361 !isInSanitizerBlacklist(SanitizerKind::KernelAddress, Fn, Loc)) 362 Fn->addFnAttr(llvm::Attribute::SanitizeAddress); 363 364 if (getLangOpts().Sanitize.has(SanitizerKind::HWAddress) && 365 !isInSanitizerBlacklist(SanitizerKind::HWAddress, Fn, Loc)) 366 Fn->addFnAttr(llvm::Attribute::SanitizeHWAddress); 367 368 if (getLangOpts().Sanitize.has(SanitizerKind::KernelHWAddress) && 369 !isInSanitizerBlacklist(SanitizerKind::KernelHWAddress, Fn, Loc)) 370 Fn->addFnAttr(llvm::Attribute::SanitizeHWAddress); 371 372 if (getLangOpts().Sanitize.has(SanitizerKind::MemTag) && 373 !isInSanitizerBlacklist(SanitizerKind::MemTag, Fn, Loc)) 374 Fn->addFnAttr(llvm::Attribute::SanitizeMemTag); 375 376 if (getLangOpts().Sanitize.has(SanitizerKind::Thread) && 377 !isInSanitizerBlacklist(SanitizerKind::Thread, Fn, Loc)) 378 Fn->addFnAttr(llvm::Attribute::SanitizeThread); 379 380 if (getLangOpts().Sanitize.has(SanitizerKind::Memory) && 381 !isInSanitizerBlacklist(SanitizerKind::Memory, Fn, Loc)) 382 Fn->addFnAttr(llvm::Attribute::SanitizeMemory); 383 384 if (getLangOpts().Sanitize.has(SanitizerKind::KernelMemory) && 385 !isInSanitizerBlacklist(SanitizerKind::KernelMemory, Fn, Loc)) 386 Fn->addFnAttr(llvm::Attribute::SanitizeMemory); 387 388 if (getLangOpts().Sanitize.has(SanitizerKind::SafeStack) && 389 !isInSanitizerBlacklist(SanitizerKind::SafeStack, Fn, Loc)) 390 Fn->addFnAttr(llvm::Attribute::SafeStack); 391 392 if (getLangOpts().Sanitize.has(SanitizerKind::ShadowCallStack) && 393 !isInSanitizerBlacklist(SanitizerKind::ShadowCallStack, Fn, Loc)) 394 Fn->addFnAttr(llvm::Attribute::ShadowCallStack); 395 396 auto RASignKind = getCodeGenOpts().getSignReturnAddress(); 397 if (RASignKind != CodeGenOptions::SignReturnAddressScope::None) { 398 Fn->addFnAttr("sign-return-address", 399 RASignKind == CodeGenOptions::SignReturnAddressScope::All 400 ? "all" 401 : "non-leaf"); 402 auto RASignKey = getCodeGenOpts().getSignReturnAddressKey(); 403 Fn->addFnAttr("sign-return-address-key", 404 RASignKey == CodeGenOptions::SignReturnAddressKeyValue::AKey 405 ? "a_key" 406 : "b_key"); 407 } 408 409 if (getCodeGenOpts().BranchTargetEnforcement) 410 Fn->addFnAttr("branch-target-enforcement"); 411 412 return Fn; 413 } 414 415 /// Create a global pointer to a function that will initialize a global 416 /// variable. The user has requested that this pointer be emitted in a specific 417 /// section. 418 void CodeGenModule::EmitPointerToInitFunc(const VarDecl *D, 419 llvm::GlobalVariable *GV, 420 llvm::Function *InitFunc, 421 InitSegAttr *ISA) { 422 llvm::GlobalVariable *PtrArray = new llvm::GlobalVariable( 423 TheModule, InitFunc->getType(), /*isConstant=*/true, 424 llvm::GlobalValue::PrivateLinkage, InitFunc, "__cxx_init_fn_ptr"); 425 PtrArray->setSection(ISA->getSection()); 426 addUsedGlobal(PtrArray); 427 428 // If the GV is already in a comdat group, then we have to join it. 429 if (llvm::Comdat *C = GV->getComdat()) 430 PtrArray->setComdat(C); 431 } 432 433 void 434 CodeGenModule::EmitCXXGlobalVarDeclInitFunc(const VarDecl *D, 435 llvm::GlobalVariable *Addr, 436 bool PerformInit) { 437 438 // According to E.2.3.1 in CUDA-7.5 Programming guide: __device__, 439 // __constant__ and __shared__ variables defined in namespace scope, 440 // that are of class type, cannot have a non-empty constructor. All 441 // the checks have been done in Sema by now. Whatever initializers 442 // are allowed are empty and we just need to ignore them here. 443 if (getLangOpts().CUDA && getLangOpts().CUDAIsDevice && 444 (D->hasAttr<CUDADeviceAttr>() || D->hasAttr<CUDAConstantAttr>() || 445 D->hasAttr<CUDASharedAttr>())) 446 return; 447 448 if (getLangOpts().OpenMP && 449 getOpenMPRuntime().emitDeclareTargetVarDefinition(D, Addr, PerformInit)) 450 return; 451 452 // Check if we've already initialized this decl. 453 auto I = DelayedCXXInitPosition.find(D); 454 if (I != DelayedCXXInitPosition.end() && I->second == ~0U) 455 return; 456 457 llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false); 458 SmallString<256> FnName; 459 { 460 llvm::raw_svector_ostream Out(FnName); 461 getCXXABI().getMangleContext().mangleDynamicInitializer(D, Out); 462 } 463 464 // Create a variable initialization function. 465 llvm::Function *Fn = 466 CreateGlobalInitOrDestructFunction(FTy, FnName.str(), 467 getTypes().arrangeNullaryFunction(), 468 D->getLocation()); 469 470 auto *ISA = D->getAttr<InitSegAttr>(); 471 CodeGenFunction(*this).GenerateCXXGlobalVarDeclInitFunc(Fn, D, Addr, 472 PerformInit); 473 474 llvm::GlobalVariable *COMDATKey = 475 supportsCOMDAT() && D->isExternallyVisible() ? Addr : nullptr; 476 477 if (D->getTLSKind()) { 478 // FIXME: Should we support init_priority for thread_local? 479 // FIXME: We only need to register one __cxa_thread_atexit function for the 480 // entire TU. 481 CXXThreadLocalInits.push_back(Fn); 482 CXXThreadLocalInitVars.push_back(D); 483 } else if (PerformInit && ISA) { 484 EmitPointerToInitFunc(D, Addr, Fn, ISA); 485 } else if (auto *IPA = D->getAttr<InitPriorityAttr>()) { 486 OrderGlobalInits Key(IPA->getPriority(), PrioritizedCXXGlobalInits.size()); 487 PrioritizedCXXGlobalInits.push_back(std::make_pair(Key, Fn)); 488 } else if (isTemplateInstantiation(D->getTemplateSpecializationKind()) || 489 getContext().GetGVALinkageForVariable(D) == GVA_DiscardableODR) { 490 // C++ [basic.start.init]p2: 491 // Definitions of explicitly specialized class template static data 492 // members have ordered initialization. Other class template static data 493 // members (i.e., implicitly or explicitly instantiated specializations) 494 // have unordered initialization. 495 // 496 // As a consequence, we can put them into their own llvm.global_ctors entry. 497 // 498 // If the global is externally visible, put the initializer into a COMDAT 499 // group with the global being initialized. On most platforms, this is a 500 // minor startup time optimization. In the MS C++ ABI, there are no guard 501 // variables, so this COMDAT key is required for correctness. 502 AddGlobalCtor(Fn, 65535, COMDATKey); 503 if (getTarget().getCXXABI().isMicrosoft() && COMDATKey) { 504 // In The MS C++, MS add template static data member in the linker 505 // drective. 506 addUsedGlobal(COMDATKey); 507 } 508 } else if (D->hasAttr<SelectAnyAttr>()) { 509 // SelectAny globals will be comdat-folded. Put the initializer into a 510 // COMDAT group associated with the global, so the initializers get folded 511 // too. 512 AddGlobalCtor(Fn, 65535, COMDATKey); 513 } else { 514 I = DelayedCXXInitPosition.find(D); // Re-do lookup in case of re-hash. 515 if (I == DelayedCXXInitPosition.end()) { 516 CXXGlobalInits.push_back(Fn); 517 } else if (I->second != ~0U) { 518 assert(I->second < CXXGlobalInits.size() && 519 CXXGlobalInits[I->second] == nullptr); 520 CXXGlobalInits[I->second] = Fn; 521 } 522 } 523 524 // Remember that we already emitted the initializer for this global. 525 DelayedCXXInitPosition[D] = ~0U; 526 } 527 528 void CodeGenModule::EmitCXXThreadLocalInitFunc() { 529 getCXXABI().EmitThreadLocalInitFuncs( 530 *this, CXXThreadLocals, CXXThreadLocalInits, CXXThreadLocalInitVars); 531 532 CXXThreadLocalInits.clear(); 533 CXXThreadLocalInitVars.clear(); 534 CXXThreadLocals.clear(); 535 } 536 537 void 538 CodeGenModule::EmitCXXGlobalInitFunc() { 539 while (!CXXGlobalInits.empty() && !CXXGlobalInits.back()) 540 CXXGlobalInits.pop_back(); 541 542 if (CXXGlobalInits.empty() && PrioritizedCXXGlobalInits.empty()) 543 return; 544 545 llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false); 546 const CGFunctionInfo &FI = getTypes().arrangeNullaryFunction(); 547 548 // Create our global initialization function. 549 if (!PrioritizedCXXGlobalInits.empty()) { 550 SmallVector<llvm::Function *, 8> LocalCXXGlobalInits; 551 llvm::array_pod_sort(PrioritizedCXXGlobalInits.begin(), 552 PrioritizedCXXGlobalInits.end()); 553 // Iterate over "chunks" of ctors with same priority and emit each chunk 554 // into separate function. Note - everything is sorted first by priority, 555 // second - by lex order, so we emit ctor functions in proper order. 556 for (SmallVectorImpl<GlobalInitData >::iterator 557 I = PrioritizedCXXGlobalInits.begin(), 558 E = PrioritizedCXXGlobalInits.end(); I != E; ) { 559 SmallVectorImpl<GlobalInitData >::iterator 560 PrioE = std::upper_bound(I + 1, E, *I, GlobalInitPriorityCmp()); 561 562 LocalCXXGlobalInits.clear(); 563 unsigned Priority = I->first.priority; 564 // Compute the function suffix from priority. Prepend with zeroes to make 565 // sure the function names are also ordered as priorities. 566 std::string PrioritySuffix = llvm::utostr(Priority); 567 // Priority is always <= 65535 (enforced by sema). 568 PrioritySuffix = std::string(6-PrioritySuffix.size(), '0')+PrioritySuffix; 569 llvm::Function *Fn = CreateGlobalInitOrDestructFunction( 570 FTy, "_GLOBAL__I_" + PrioritySuffix, FI); 571 572 for (; I < PrioE; ++I) 573 LocalCXXGlobalInits.push_back(I->second); 574 575 CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn, LocalCXXGlobalInits); 576 AddGlobalCtor(Fn, Priority); 577 } 578 PrioritizedCXXGlobalInits.clear(); 579 } 580 581 // Include the filename in the symbol name. Including "sub_" matches gcc and 582 // makes sure these symbols appear lexicographically behind the symbols with 583 // priority emitted above. 584 SmallString<128> FileName = llvm::sys::path::filename(getModule().getName()); 585 if (FileName.empty()) 586 FileName = "<null>"; 587 588 for (size_t i = 0; i < FileName.size(); ++i) { 589 // Replace everything that's not [a-zA-Z0-9._] with a _. This set happens 590 // to be the set of C preprocessing numbers. 591 if (!isPreprocessingNumberBody(FileName[i])) 592 FileName[i] = '_'; 593 } 594 595 llvm::Function *Fn = CreateGlobalInitOrDestructFunction( 596 FTy, llvm::Twine("_GLOBAL__sub_I_", FileName), FI); 597 598 CodeGenFunction(*this).GenerateCXXGlobalInitFunc(Fn, CXXGlobalInits); 599 AddGlobalCtor(Fn); 600 601 // In OpenCL global init functions must be converted to kernels in order to 602 // be able to launch them from the host. 603 // FIXME: Some more work might be needed to handle destructors correctly. 604 // Current initialization function makes use of function pointers callbacks. 605 // We can't support function pointers especially between host and device. 606 // However it seems global destruction has little meaning without any 607 // dynamic resource allocation on the device and program scope variables are 608 // destroyed by the runtime when program is released. 609 if (getLangOpts().OpenCL) { 610 GenOpenCLArgMetadata(Fn); 611 Fn->setCallingConv(llvm::CallingConv::SPIR_KERNEL); 612 } 613 614 CXXGlobalInits.clear(); 615 } 616 617 void CodeGenModule::EmitCXXGlobalDtorFunc() { 618 if (CXXGlobalDtors.empty()) 619 return; 620 621 llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false); 622 623 // Create our global destructor function. 624 const CGFunctionInfo &FI = getTypes().arrangeNullaryFunction(); 625 llvm::Function *Fn = 626 CreateGlobalInitOrDestructFunction(FTy, "_GLOBAL__D_a", FI); 627 628 CodeGenFunction(*this).GenerateCXXGlobalDtorsFunc(Fn, CXXGlobalDtors); 629 AddGlobalDtor(Fn); 630 } 631 632 /// Emit the code necessary to initialize the given global variable. 633 void CodeGenFunction::GenerateCXXGlobalVarDeclInitFunc(llvm::Function *Fn, 634 const VarDecl *D, 635 llvm::GlobalVariable *Addr, 636 bool PerformInit) { 637 // Check if we need to emit debug info for variable initializer. 638 if (D->hasAttr<NoDebugAttr>()) 639 DebugInfo = nullptr; // disable debug info indefinitely for this function 640 641 CurEHLocation = D->getBeginLoc(); 642 643 StartFunction(GlobalDecl(D, DynamicInitKind::Initializer), 644 getContext().VoidTy, Fn, getTypes().arrangeNullaryFunction(), 645 FunctionArgList(), D->getLocation(), 646 D->getInit()->getExprLoc()); 647 648 // Use guarded initialization if the global variable is weak. This 649 // occurs for, e.g., instantiated static data members and 650 // definitions explicitly marked weak. 651 // 652 // Also use guarded initialization for a variable with dynamic TLS and 653 // unordered initialization. (If the initialization is ordered, the ABI 654 // layer will guard the whole-TU initialization for us.) 655 if (Addr->hasWeakLinkage() || Addr->hasLinkOnceLinkage() || 656 (D->getTLSKind() == VarDecl::TLS_Dynamic && 657 isTemplateInstantiation(D->getTemplateSpecializationKind()))) { 658 EmitCXXGuardedInit(*D, Addr, PerformInit); 659 } else { 660 EmitCXXGlobalVarDeclInit(*D, Addr, PerformInit); 661 } 662 663 FinishFunction(); 664 } 665 666 void 667 CodeGenFunction::GenerateCXXGlobalInitFunc(llvm::Function *Fn, 668 ArrayRef<llvm::Function *> Decls, 669 ConstantAddress Guard) { 670 { 671 auto NL = ApplyDebugLocation::CreateEmpty(*this); 672 StartFunction(GlobalDecl(), getContext().VoidTy, Fn, 673 getTypes().arrangeNullaryFunction(), FunctionArgList()); 674 // Emit an artificial location for this function. 675 auto AL = ApplyDebugLocation::CreateArtificial(*this); 676 677 llvm::BasicBlock *ExitBlock = nullptr; 678 if (Guard.isValid()) { 679 // If we have a guard variable, check whether we've already performed 680 // these initializations. This happens for TLS initialization functions. 681 llvm::Value *GuardVal = Builder.CreateLoad(Guard); 682 llvm::Value *Uninit = Builder.CreateIsNull(GuardVal, 683 "guard.uninitialized"); 684 llvm::BasicBlock *InitBlock = createBasicBlock("init"); 685 ExitBlock = createBasicBlock("exit"); 686 EmitCXXGuardedInitBranch(Uninit, InitBlock, ExitBlock, 687 GuardKind::TlsGuard, nullptr); 688 EmitBlock(InitBlock); 689 // Mark as initialized before initializing anything else. If the 690 // initializers use previously-initialized thread_local vars, that's 691 // probably supposed to be OK, but the standard doesn't say. 692 Builder.CreateStore(llvm::ConstantInt::get(GuardVal->getType(),1), Guard); 693 694 // The guard variable can't ever change again. 695 EmitInvariantStart( 696 Guard.getPointer(), 697 CharUnits::fromQuantity( 698 CGM.getDataLayout().getTypeAllocSize(GuardVal->getType()))); 699 } 700 701 RunCleanupsScope Scope(*this); 702 703 // When building in Objective-C++ ARC mode, create an autorelease pool 704 // around the global initializers. 705 if (getLangOpts().ObjCAutoRefCount && getLangOpts().CPlusPlus) { 706 llvm::Value *token = EmitObjCAutoreleasePoolPush(); 707 EmitObjCAutoreleasePoolCleanup(token); 708 } 709 710 for (unsigned i = 0, e = Decls.size(); i != e; ++i) 711 if (Decls[i]) 712 EmitRuntimeCall(Decls[i]); 713 714 Scope.ForceCleanup(); 715 716 if (ExitBlock) { 717 Builder.CreateBr(ExitBlock); 718 EmitBlock(ExitBlock); 719 } 720 } 721 722 FinishFunction(); 723 } 724 725 void CodeGenFunction::GenerateCXXGlobalDtorsFunc( 726 llvm::Function *Fn, 727 const std::vector<std::tuple<llvm::FunctionType *, llvm::WeakTrackingVH, 728 llvm::Constant *>> &DtorsAndObjects) { 729 { 730 auto NL = ApplyDebugLocation::CreateEmpty(*this); 731 StartFunction(GlobalDecl(), getContext().VoidTy, Fn, 732 getTypes().arrangeNullaryFunction(), FunctionArgList()); 733 // Emit an artificial location for this function. 734 auto AL = ApplyDebugLocation::CreateArtificial(*this); 735 736 // Emit the dtors, in reverse order from construction. 737 for (unsigned i = 0, e = DtorsAndObjects.size(); i != e; ++i) { 738 llvm::FunctionType *CalleeTy; 739 llvm::Value *Callee; 740 llvm::Constant *Arg; 741 std::tie(CalleeTy, Callee, Arg) = DtorsAndObjects[e - i - 1]; 742 llvm::CallInst *CI = Builder.CreateCall(CalleeTy, Callee, Arg); 743 // Make sure the call and the callee agree on calling convention. 744 if (llvm::Function *F = dyn_cast<llvm::Function>(Callee)) 745 CI->setCallingConv(F->getCallingConv()); 746 } 747 } 748 749 FinishFunction(); 750 } 751 752 /// generateDestroyHelper - Generates a helper function which, when 753 /// invoked, destroys the given object. The address of the object 754 /// should be in global memory. 755 llvm::Function *CodeGenFunction::generateDestroyHelper( 756 Address addr, QualType type, Destroyer *destroyer, 757 bool useEHCleanupForArray, const VarDecl *VD) { 758 FunctionArgList args; 759 ImplicitParamDecl Dst(getContext(), getContext().VoidPtrTy, 760 ImplicitParamDecl::Other); 761 args.push_back(&Dst); 762 763 const CGFunctionInfo &FI = 764 CGM.getTypes().arrangeBuiltinFunctionDeclaration(getContext().VoidTy, args); 765 llvm::FunctionType *FTy = CGM.getTypes().GetFunctionType(FI); 766 llvm::Function *fn = CGM.CreateGlobalInitOrDestructFunction( 767 FTy, "__cxx_global_array_dtor", FI, VD->getLocation()); 768 769 CurEHLocation = VD->getBeginLoc(); 770 771 StartFunction(VD, getContext().VoidTy, fn, FI, args); 772 773 emitDestroy(addr, type, destroyer, useEHCleanupForArray); 774 775 FinishFunction(); 776 777 return fn; 778 } 779