1 //===--- MicrosoftCXXABI.cpp - Emit LLVM Code from ASTs for a Module ------===// 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 provides C++ code generation targeting the Microsoft Visual C++ ABI. 10 // The class in this file generates structures that follow the Microsoft 11 // Visual C++ ABI, which is actually not very well documented at all outside 12 // of Microsoft. 13 // 14 //===----------------------------------------------------------------------===// 15 16 #include "ABIInfo.h" 17 #include "CGCXXABI.h" 18 #include "CGCleanup.h" 19 #include "CGVTables.h" 20 #include "CodeGenModule.h" 21 #include "CodeGenTypes.h" 22 #include "TargetInfo.h" 23 #include "clang/AST/Attr.h" 24 #include "clang/AST/CXXInheritance.h" 25 #include "clang/AST/Decl.h" 26 #include "clang/AST/DeclCXX.h" 27 #include "clang/AST/StmtCXX.h" 28 #include "clang/AST/VTableBuilder.h" 29 #include "clang/CodeGen/ConstantInitBuilder.h" 30 #include "llvm/ADT/StringExtras.h" 31 #include "llvm/ADT/StringSet.h" 32 #include "llvm/IR/Intrinsics.h" 33 34 using namespace clang; 35 using namespace CodeGen; 36 37 namespace { 38 39 /// Holds all the vbtable globals for a given class. 40 struct VBTableGlobals { 41 const VPtrInfoVector *VBTables; 42 SmallVector<llvm::GlobalVariable *, 2> Globals; 43 }; 44 45 class MicrosoftCXXABI : public CGCXXABI { 46 public: 47 MicrosoftCXXABI(CodeGenModule &CGM) 48 : CGCXXABI(CGM), BaseClassDescriptorType(nullptr), 49 ClassHierarchyDescriptorType(nullptr), 50 CompleteObjectLocatorType(nullptr), CatchableTypeType(nullptr), 51 ThrowInfoType(nullptr) { 52 assert(!(CGM.getLangOpts().isExplicitDefaultVisibilityExportMapping() || 53 CGM.getLangOpts().isAllDefaultVisibilityExportMapping()) && 54 "visibility export mapping option unimplemented in this ABI"); 55 } 56 57 bool HasThisReturn(GlobalDecl GD) const override; 58 bool hasMostDerivedReturn(GlobalDecl GD) const override; 59 60 bool classifyReturnType(CGFunctionInfo &FI) const override; 61 62 RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const override; 63 64 bool isSRetParameterAfterThis() const override { return true; } 65 66 bool isThisCompleteObject(GlobalDecl GD) const override { 67 // The Microsoft ABI doesn't use separate complete-object vs. 68 // base-object variants of constructors, but it does of destructors. 69 if (isa<CXXDestructorDecl>(GD.getDecl())) { 70 switch (GD.getDtorType()) { 71 case Dtor_Complete: 72 case Dtor_Deleting: 73 return true; 74 75 case Dtor_Base: 76 return false; 77 78 case Dtor_Comdat: llvm_unreachable("emitting dtor comdat as function?"); 79 } 80 llvm_unreachable("bad dtor kind"); 81 } 82 83 // No other kinds. 84 return false; 85 } 86 87 size_t getSrcArgforCopyCtor(const CXXConstructorDecl *CD, 88 FunctionArgList &Args) const override { 89 assert(Args.size() >= 2 && 90 "expected the arglist to have at least two args!"); 91 // The 'most_derived' parameter goes second if the ctor is variadic and 92 // has v-bases. 93 if (CD->getParent()->getNumVBases() > 0 && 94 CD->getType()->castAs<FunctionProtoType>()->isVariadic()) 95 return 2; 96 return 1; 97 } 98 99 std::vector<CharUnits> getVBPtrOffsets(const CXXRecordDecl *RD) override { 100 std::vector<CharUnits> VBPtrOffsets; 101 const ASTContext &Context = getContext(); 102 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); 103 104 const VBTableGlobals &VBGlobals = enumerateVBTables(RD); 105 for (const std::unique_ptr<VPtrInfo> &VBT : *VBGlobals.VBTables) { 106 const ASTRecordLayout &SubobjectLayout = 107 Context.getASTRecordLayout(VBT->IntroducingObject); 108 CharUnits Offs = VBT->NonVirtualOffset; 109 Offs += SubobjectLayout.getVBPtrOffset(); 110 if (VBT->getVBaseWithVPtr()) 111 Offs += Layout.getVBaseClassOffset(VBT->getVBaseWithVPtr()); 112 VBPtrOffsets.push_back(Offs); 113 } 114 llvm::array_pod_sort(VBPtrOffsets.begin(), VBPtrOffsets.end()); 115 return VBPtrOffsets; 116 } 117 118 StringRef GetPureVirtualCallName() override { return "_purecall"; } 119 StringRef GetDeletedVirtualCallName() override { return "_purecall"; } 120 121 void emitVirtualObjectDelete(CodeGenFunction &CGF, const CXXDeleteExpr *DE, 122 Address Ptr, QualType ElementType, 123 const CXXDestructorDecl *Dtor) override; 124 125 void emitRethrow(CodeGenFunction &CGF, bool isNoReturn) override; 126 void emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) override; 127 128 void emitBeginCatch(CodeGenFunction &CGF, const CXXCatchStmt *C) override; 129 130 llvm::GlobalVariable *getMSCompleteObjectLocator(const CXXRecordDecl *RD, 131 const VPtrInfo &Info); 132 133 llvm::Constant *getAddrOfRTTIDescriptor(QualType Ty) override; 134 CatchTypeInfo 135 getAddrOfCXXCatchHandlerType(QualType Ty, QualType CatchHandlerType) override; 136 137 /// MSVC needs an extra flag to indicate a catchall. 138 CatchTypeInfo getCatchAllTypeInfo() override { 139 // For -EHa catch(...) must handle HW exception 140 // Adjective = HT_IsStdDotDot (0x40), only catch C++ exceptions 141 if (getContext().getLangOpts().EHAsynch) 142 return CatchTypeInfo{nullptr, 0}; 143 else 144 return CatchTypeInfo{nullptr, 0x40}; 145 } 146 147 bool shouldTypeidBeNullChecked(QualType SrcRecordTy) override; 148 void EmitBadTypeidCall(CodeGenFunction &CGF) override; 149 llvm::Value *EmitTypeid(CodeGenFunction &CGF, QualType SrcRecordTy, 150 Address ThisPtr, 151 llvm::Type *StdTypeInfoPtrTy) override; 152 153 bool shouldDynamicCastCallBeNullChecked(bool SrcIsPtr, 154 QualType SrcRecordTy) override; 155 156 bool shouldEmitExactDynamicCast(QualType DestRecordTy) override { 157 // TODO: Add support for exact dynamic_casts. 158 return false; 159 } 160 llvm::Value *emitExactDynamicCast(CodeGenFunction &CGF, Address Value, 161 QualType SrcRecordTy, QualType DestTy, 162 QualType DestRecordTy, 163 llvm::BasicBlock *CastSuccess, 164 llvm::BasicBlock *CastFail) override { 165 llvm_unreachable("unsupported"); 166 } 167 168 llvm::Value *emitDynamicCastCall(CodeGenFunction &CGF, Address Value, 169 QualType SrcRecordTy, QualType DestTy, 170 QualType DestRecordTy, 171 llvm::BasicBlock *CastEnd) override; 172 173 llvm::Value *emitDynamicCastToVoid(CodeGenFunction &CGF, Address Value, 174 QualType SrcRecordTy) override; 175 176 bool EmitBadCastCall(CodeGenFunction &CGF) override; 177 bool canSpeculativelyEmitVTable(const CXXRecordDecl *RD) const override { 178 return false; 179 } 180 181 llvm::Value * 182 GetVirtualBaseClassOffset(CodeGenFunction &CGF, Address This, 183 const CXXRecordDecl *ClassDecl, 184 const CXXRecordDecl *BaseClassDecl) override; 185 186 llvm::BasicBlock * 187 EmitCtorCompleteObjectHandler(CodeGenFunction &CGF, 188 const CXXRecordDecl *RD) override; 189 190 llvm::BasicBlock * 191 EmitDtorCompleteObjectHandler(CodeGenFunction &CGF); 192 193 void initializeHiddenVirtualInheritanceMembers(CodeGenFunction &CGF, 194 const CXXRecordDecl *RD) override; 195 196 void EmitCXXConstructors(const CXXConstructorDecl *D) override; 197 198 // Background on MSVC destructors 199 // ============================== 200 // 201 // Both Itanium and MSVC ABIs have destructor variants. The variant names 202 // roughly correspond in the following way: 203 // Itanium Microsoft 204 // Base -> no name, just ~Class 205 // Complete -> vbase destructor 206 // Deleting -> scalar deleting destructor 207 // vector deleting destructor 208 // 209 // The base and complete destructors are the same as in Itanium, although the 210 // complete destructor does not accept a VTT parameter when there are virtual 211 // bases. A separate mechanism involving vtordisps is used to ensure that 212 // virtual methods of destroyed subobjects are not called. 213 // 214 // The deleting destructors accept an i32 bitfield as a second parameter. Bit 215 // 1 indicates if the memory should be deleted. Bit 2 indicates if the this 216 // pointer points to an array. The scalar deleting destructor assumes that 217 // bit 2 is zero, and therefore does not contain a loop. 218 // 219 // For virtual destructors, only one entry is reserved in the vftable, and it 220 // always points to the vector deleting destructor. The vector deleting 221 // destructor is the most general, so it can be used to destroy objects in 222 // place, delete single heap objects, or delete arrays. 223 // 224 // A TU defining a non-inline destructor is only guaranteed to emit a base 225 // destructor, and all of the other variants are emitted on an as-needed basis 226 // in COMDATs. Because a non-base destructor can be emitted in a TU that 227 // lacks a definition for the destructor, non-base destructors must always 228 // delegate to or alias the base destructor. 229 230 AddedStructorArgCounts 231 buildStructorSignature(GlobalDecl GD, 232 SmallVectorImpl<CanQualType> &ArgTys) override; 233 234 /// Non-base dtors should be emitted as delegating thunks in this ABI. 235 bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor, 236 CXXDtorType DT) const override { 237 return DT != Dtor_Base; 238 } 239 240 void setCXXDestructorDLLStorage(llvm::GlobalValue *GV, 241 const CXXDestructorDecl *Dtor, 242 CXXDtorType DT) const override; 243 244 llvm::GlobalValue::LinkageTypes 245 getCXXDestructorLinkage(GVALinkage Linkage, const CXXDestructorDecl *Dtor, 246 CXXDtorType DT) const override; 247 248 void EmitCXXDestructors(const CXXDestructorDecl *D) override; 249 250 const CXXRecordDecl *getThisArgumentTypeForMethod(GlobalDecl GD) override { 251 auto *MD = cast<CXXMethodDecl>(GD.getDecl()); 252 253 if (MD->isVirtual()) { 254 GlobalDecl LookupGD = GD; 255 if (const auto *DD = dyn_cast<CXXDestructorDecl>(MD)) { 256 // Complete dtors take a pointer to the complete object, 257 // thus don't need adjustment. 258 if (GD.getDtorType() == Dtor_Complete) 259 return MD->getParent(); 260 261 // There's only Dtor_Deleting in vftable but it shares the this 262 // adjustment with the base one, so look up the deleting one instead. 263 LookupGD = GlobalDecl(DD, Dtor_Deleting); 264 } 265 MethodVFTableLocation ML = 266 CGM.getMicrosoftVTableContext().getMethodVFTableLocation(LookupGD); 267 268 // The vbases might be ordered differently in the final overrider object 269 // and the complete object, so the "this" argument may sometimes point to 270 // memory that has no particular type (e.g. past the complete object). 271 // In this case, we just use a generic pointer type. 272 // FIXME: might want to have a more precise type in the non-virtual 273 // multiple inheritance case. 274 if (ML.VBase || !ML.VFPtrOffset.isZero()) 275 return nullptr; 276 } 277 return MD->getParent(); 278 } 279 280 Address 281 adjustThisArgumentForVirtualFunctionCall(CodeGenFunction &CGF, GlobalDecl GD, 282 Address This, 283 bool VirtualCall) override; 284 285 void addImplicitStructorParams(CodeGenFunction &CGF, QualType &ResTy, 286 FunctionArgList &Params) override; 287 288 void EmitInstanceFunctionProlog(CodeGenFunction &CGF) override; 289 290 AddedStructorArgs getImplicitConstructorArgs(CodeGenFunction &CGF, 291 const CXXConstructorDecl *D, 292 CXXCtorType Type, 293 bool ForVirtualBase, 294 bool Delegating) override; 295 296 llvm::Value *getCXXDestructorImplicitParam(CodeGenFunction &CGF, 297 const CXXDestructorDecl *DD, 298 CXXDtorType Type, 299 bool ForVirtualBase, 300 bool Delegating) override; 301 302 void EmitDestructorCall(CodeGenFunction &CGF, const CXXDestructorDecl *DD, 303 CXXDtorType Type, bool ForVirtualBase, 304 bool Delegating, Address This, 305 QualType ThisTy) override; 306 307 void emitVTableTypeMetadata(const VPtrInfo &Info, const CXXRecordDecl *RD, 308 llvm::GlobalVariable *VTable); 309 310 void emitVTableDefinitions(CodeGenVTables &CGVT, 311 const CXXRecordDecl *RD) override; 312 313 bool isVirtualOffsetNeededForVTableField(CodeGenFunction &CGF, 314 CodeGenFunction::VPtr Vptr) override; 315 316 /// Don't initialize vptrs if dynamic class 317 /// is marked with the 'novtable' attribute. 318 bool doStructorsInitializeVPtrs(const CXXRecordDecl *VTableClass) override { 319 return !VTableClass->hasAttr<MSNoVTableAttr>(); 320 } 321 322 llvm::Constant * 323 getVTableAddressPoint(BaseSubobject Base, 324 const CXXRecordDecl *VTableClass) override; 325 326 llvm::Value *getVTableAddressPointInStructor( 327 CodeGenFunction &CGF, const CXXRecordDecl *VTableClass, 328 BaseSubobject Base, const CXXRecordDecl *NearestVBase) override; 329 330 llvm::GlobalVariable *getAddrOfVTable(const CXXRecordDecl *RD, 331 CharUnits VPtrOffset) override; 332 333 CGCallee getVirtualFunctionPointer(CodeGenFunction &CGF, GlobalDecl GD, 334 Address This, llvm::Type *Ty, 335 SourceLocation Loc) override; 336 337 llvm::Value *EmitVirtualDestructorCall(CodeGenFunction &CGF, 338 const CXXDestructorDecl *Dtor, 339 CXXDtorType DtorType, Address This, 340 DeleteOrMemberCallExpr E) override; 341 342 void adjustCallArgsForDestructorThunk(CodeGenFunction &CGF, GlobalDecl GD, 343 CallArgList &CallArgs) override { 344 assert(GD.getDtorType() == Dtor_Deleting && 345 "Only deleting destructor thunks are available in this ABI"); 346 CallArgs.add(RValue::get(getStructorImplicitParamValue(CGF)), 347 getContext().IntTy); 348 } 349 350 void emitVirtualInheritanceTables(const CXXRecordDecl *RD) override; 351 352 llvm::GlobalVariable * 353 getAddrOfVBTable(const VPtrInfo &VBT, const CXXRecordDecl *RD, 354 llvm::GlobalVariable::LinkageTypes Linkage); 355 356 llvm::GlobalVariable * 357 getAddrOfVirtualDisplacementMap(const CXXRecordDecl *SrcRD, 358 const CXXRecordDecl *DstRD) { 359 SmallString<256> OutName; 360 llvm::raw_svector_ostream Out(OutName); 361 getMangleContext().mangleCXXVirtualDisplacementMap(SrcRD, DstRD, Out); 362 StringRef MangledName = OutName.str(); 363 364 if (auto *VDispMap = CGM.getModule().getNamedGlobal(MangledName)) 365 return VDispMap; 366 367 MicrosoftVTableContext &VTContext = CGM.getMicrosoftVTableContext(); 368 unsigned NumEntries = 1 + SrcRD->getNumVBases(); 369 SmallVector<llvm::Constant *, 4> Map(NumEntries, 370 llvm::UndefValue::get(CGM.IntTy)); 371 Map[0] = llvm::ConstantInt::get(CGM.IntTy, 0); 372 bool AnyDifferent = false; 373 for (const auto &I : SrcRD->vbases()) { 374 const CXXRecordDecl *VBase = I.getType()->getAsCXXRecordDecl(); 375 if (!DstRD->isVirtuallyDerivedFrom(VBase)) 376 continue; 377 378 unsigned SrcVBIndex = VTContext.getVBTableIndex(SrcRD, VBase); 379 unsigned DstVBIndex = VTContext.getVBTableIndex(DstRD, VBase); 380 Map[SrcVBIndex] = llvm::ConstantInt::get(CGM.IntTy, DstVBIndex * 4); 381 AnyDifferent |= SrcVBIndex != DstVBIndex; 382 } 383 // This map would be useless, don't use it. 384 if (!AnyDifferent) 385 return nullptr; 386 387 llvm::ArrayType *VDispMapTy = llvm::ArrayType::get(CGM.IntTy, Map.size()); 388 llvm::Constant *Init = llvm::ConstantArray::get(VDispMapTy, Map); 389 llvm::GlobalValue::LinkageTypes Linkage = 390 SrcRD->isExternallyVisible() && DstRD->isExternallyVisible() 391 ? llvm::GlobalValue::LinkOnceODRLinkage 392 : llvm::GlobalValue::InternalLinkage; 393 auto *VDispMap = new llvm::GlobalVariable( 394 CGM.getModule(), VDispMapTy, /*isConstant=*/true, Linkage, 395 /*Initializer=*/Init, MangledName); 396 return VDispMap; 397 } 398 399 void emitVBTableDefinition(const VPtrInfo &VBT, const CXXRecordDecl *RD, 400 llvm::GlobalVariable *GV) const; 401 402 void setThunkLinkage(llvm::Function *Thunk, bool ForVTable, 403 GlobalDecl GD, bool ReturnAdjustment) override { 404 GVALinkage Linkage = 405 getContext().GetGVALinkageForFunction(cast<FunctionDecl>(GD.getDecl())); 406 407 if (Linkage == GVA_Internal) 408 Thunk->setLinkage(llvm::GlobalValue::InternalLinkage); 409 else if (ReturnAdjustment) 410 Thunk->setLinkage(llvm::GlobalValue::WeakODRLinkage); 411 else 412 Thunk->setLinkage(llvm::GlobalValue::LinkOnceODRLinkage); 413 } 414 415 bool exportThunk() override { return false; } 416 417 llvm::Value *performThisAdjustment(CodeGenFunction &CGF, Address This, 418 const CXXRecordDecl * /*UnadjustedClass*/, 419 const ThunkInfo &TI) override; 420 421 llvm::Value *performReturnAdjustment(CodeGenFunction &CGF, Address Ret, 422 const CXXRecordDecl * /*UnadjustedClass*/, 423 const ReturnAdjustment &RA) override; 424 425 void EmitThreadLocalInitFuncs( 426 CodeGenModule &CGM, ArrayRef<const VarDecl *> CXXThreadLocals, 427 ArrayRef<llvm::Function *> CXXThreadLocalInits, 428 ArrayRef<const VarDecl *> CXXThreadLocalInitVars) override; 429 430 bool usesThreadWrapperFunction(const VarDecl *VD) const override { 431 return getContext().getLangOpts().isCompatibleWithMSVC( 432 LangOptions::MSVC2019_5) && 433 (!isEmittedWithConstantInitializer(VD) || mayNeedDestruction(VD)); 434 } 435 LValue EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF, const VarDecl *VD, 436 QualType LValType) override; 437 438 void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D, 439 llvm::GlobalVariable *DeclPtr, 440 bool PerformInit) override; 441 void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D, 442 llvm::FunctionCallee Dtor, 443 llvm::Constant *Addr) override; 444 445 // ==== Notes on array cookies ========= 446 // 447 // MSVC seems to only use cookies when the class has a destructor; a 448 // two-argument usual array deallocation function isn't sufficient. 449 // 450 // For example, this code prints "100" and "1": 451 // struct A { 452 // char x; 453 // void *operator new[](size_t sz) { 454 // printf("%u\n", sz); 455 // return malloc(sz); 456 // } 457 // void operator delete[](void *p, size_t sz) { 458 // printf("%u\n", sz); 459 // free(p); 460 // } 461 // }; 462 // int main() { 463 // A *p = new A[100]; 464 // delete[] p; 465 // } 466 // Whereas it prints "104" and "104" if you give A a destructor. 467 468 bool requiresArrayCookie(const CXXDeleteExpr *expr, 469 QualType elementType) override; 470 bool requiresArrayCookie(const CXXNewExpr *expr) override; 471 CharUnits getArrayCookieSizeImpl(QualType type) override; 472 Address InitializeArrayCookie(CodeGenFunction &CGF, 473 Address NewPtr, 474 llvm::Value *NumElements, 475 const CXXNewExpr *expr, 476 QualType ElementType) override; 477 llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF, 478 Address allocPtr, 479 CharUnits cookieSize) override; 480 481 friend struct MSRTTIBuilder; 482 483 bool isImageRelative() const { 484 return CGM.getTarget().getPointerWidth(LangAS::Default) == 64; 485 } 486 487 // 5 routines for constructing the llvm types for MS RTTI structs. 488 llvm::StructType *getTypeDescriptorType(StringRef TypeInfoString) { 489 llvm::SmallString<32> TDTypeName("rtti.TypeDescriptor"); 490 TDTypeName += llvm::utostr(TypeInfoString.size()); 491 llvm::StructType *&TypeDescriptorType = 492 TypeDescriptorTypeMap[TypeInfoString.size()]; 493 if (TypeDescriptorType) 494 return TypeDescriptorType; 495 llvm::Type *FieldTypes[] = { 496 CGM.Int8PtrPtrTy, 497 CGM.Int8PtrTy, 498 llvm::ArrayType::get(CGM.Int8Ty, TypeInfoString.size() + 1)}; 499 TypeDescriptorType = 500 llvm::StructType::create(CGM.getLLVMContext(), FieldTypes, TDTypeName); 501 return TypeDescriptorType; 502 } 503 504 llvm::Type *getImageRelativeType(llvm::Type *PtrType) { 505 if (!isImageRelative()) 506 return PtrType; 507 return CGM.IntTy; 508 } 509 510 llvm::StructType *getBaseClassDescriptorType() { 511 if (BaseClassDescriptorType) 512 return BaseClassDescriptorType; 513 llvm::Type *FieldTypes[] = { 514 getImageRelativeType(CGM.Int8PtrTy), 515 CGM.IntTy, 516 CGM.IntTy, 517 CGM.IntTy, 518 CGM.IntTy, 519 CGM.IntTy, 520 getImageRelativeType(getClassHierarchyDescriptorType()->getPointerTo()), 521 }; 522 BaseClassDescriptorType = llvm::StructType::create( 523 CGM.getLLVMContext(), FieldTypes, "rtti.BaseClassDescriptor"); 524 return BaseClassDescriptorType; 525 } 526 527 llvm::StructType *getClassHierarchyDescriptorType() { 528 if (ClassHierarchyDescriptorType) 529 return ClassHierarchyDescriptorType; 530 // Forward-declare RTTIClassHierarchyDescriptor to break a cycle. 531 ClassHierarchyDescriptorType = llvm::StructType::create( 532 CGM.getLLVMContext(), "rtti.ClassHierarchyDescriptor"); 533 llvm::Type *FieldTypes[] = { 534 CGM.IntTy, 535 CGM.IntTy, 536 CGM.IntTy, 537 getImageRelativeType( 538 getBaseClassDescriptorType()->getPointerTo()->getPointerTo()), 539 }; 540 ClassHierarchyDescriptorType->setBody(FieldTypes); 541 return ClassHierarchyDescriptorType; 542 } 543 544 llvm::StructType *getCompleteObjectLocatorType() { 545 if (CompleteObjectLocatorType) 546 return CompleteObjectLocatorType; 547 CompleteObjectLocatorType = llvm::StructType::create( 548 CGM.getLLVMContext(), "rtti.CompleteObjectLocator"); 549 llvm::Type *FieldTypes[] = { 550 CGM.IntTy, 551 CGM.IntTy, 552 CGM.IntTy, 553 getImageRelativeType(CGM.Int8PtrTy), 554 getImageRelativeType(getClassHierarchyDescriptorType()->getPointerTo()), 555 getImageRelativeType(CompleteObjectLocatorType), 556 }; 557 llvm::ArrayRef<llvm::Type *> FieldTypesRef(FieldTypes); 558 if (!isImageRelative()) 559 FieldTypesRef = FieldTypesRef.drop_back(); 560 CompleteObjectLocatorType->setBody(FieldTypesRef); 561 return CompleteObjectLocatorType; 562 } 563 564 llvm::GlobalVariable *getImageBase() { 565 StringRef Name = "__ImageBase"; 566 if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(Name)) 567 return GV; 568 569 auto *GV = new llvm::GlobalVariable(CGM.getModule(), CGM.Int8Ty, 570 /*isConstant=*/true, 571 llvm::GlobalValue::ExternalLinkage, 572 /*Initializer=*/nullptr, Name); 573 CGM.setDSOLocal(GV); 574 return GV; 575 } 576 577 llvm::Constant *getImageRelativeConstant(llvm::Constant *PtrVal) { 578 if (!isImageRelative()) 579 return PtrVal; 580 581 if (PtrVal->isNullValue()) 582 return llvm::Constant::getNullValue(CGM.IntTy); 583 584 llvm::Constant *ImageBaseAsInt = 585 llvm::ConstantExpr::getPtrToInt(getImageBase(), CGM.IntPtrTy); 586 llvm::Constant *PtrValAsInt = 587 llvm::ConstantExpr::getPtrToInt(PtrVal, CGM.IntPtrTy); 588 llvm::Constant *Diff = 589 llvm::ConstantExpr::getSub(PtrValAsInt, ImageBaseAsInt, 590 /*HasNUW=*/true, /*HasNSW=*/true); 591 return llvm::ConstantExpr::getTrunc(Diff, CGM.IntTy); 592 } 593 594 private: 595 MicrosoftMangleContext &getMangleContext() { 596 return cast<MicrosoftMangleContext>(CodeGen::CGCXXABI::getMangleContext()); 597 } 598 599 llvm::Constant *getZeroInt() { 600 return llvm::ConstantInt::get(CGM.IntTy, 0); 601 } 602 603 llvm::Constant *getAllOnesInt() { 604 return llvm::Constant::getAllOnesValue(CGM.IntTy); 605 } 606 607 CharUnits getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD) override; 608 609 void 610 GetNullMemberPointerFields(const MemberPointerType *MPT, 611 llvm::SmallVectorImpl<llvm::Constant *> &fields); 612 613 /// Shared code for virtual base adjustment. Returns the offset from 614 /// the vbptr to the virtual base. Optionally returns the address of the 615 /// vbptr itself. 616 llvm::Value *GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF, 617 Address Base, 618 llvm::Value *VBPtrOffset, 619 llvm::Value *VBTableOffset, 620 llvm::Value **VBPtr = nullptr); 621 622 llvm::Value *GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF, 623 Address Base, 624 int32_t VBPtrOffset, 625 int32_t VBTableOffset, 626 llvm::Value **VBPtr = nullptr) { 627 assert(VBTableOffset % 4 == 0 && "should be byte offset into table of i32s"); 628 llvm::Value *VBPOffset = llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset), 629 *VBTOffset = llvm::ConstantInt::get(CGM.IntTy, VBTableOffset); 630 return GetVBaseOffsetFromVBPtr(CGF, Base, VBPOffset, VBTOffset, VBPtr); 631 } 632 633 std::tuple<Address, llvm::Value *, const CXXRecordDecl *> 634 performBaseAdjustment(CodeGenFunction &CGF, Address Value, 635 QualType SrcRecordTy); 636 637 /// Performs a full virtual base adjustment. Used to dereference 638 /// pointers to members of virtual bases. 639 llvm::Value *AdjustVirtualBase(CodeGenFunction &CGF, const Expr *E, 640 const CXXRecordDecl *RD, Address Base, 641 llvm::Value *VirtualBaseAdjustmentOffset, 642 llvm::Value *VBPtrOffset /* optional */); 643 644 /// Emits a full member pointer with the fields common to data and 645 /// function member pointers. 646 llvm::Constant *EmitFullMemberPointer(llvm::Constant *FirstField, 647 bool IsMemberFunction, 648 const CXXRecordDecl *RD, 649 CharUnits NonVirtualBaseAdjustment, 650 unsigned VBTableIndex); 651 652 bool MemberPointerConstantIsNull(const MemberPointerType *MPT, 653 llvm::Constant *MP); 654 655 /// - Initialize all vbptrs of 'this' with RD as the complete type. 656 void EmitVBPtrStores(CodeGenFunction &CGF, const CXXRecordDecl *RD); 657 658 /// Caching wrapper around VBTableBuilder::enumerateVBTables(). 659 const VBTableGlobals &enumerateVBTables(const CXXRecordDecl *RD); 660 661 /// Generate a thunk for calling a virtual member function MD. 662 llvm::Function *EmitVirtualMemPtrThunk(const CXXMethodDecl *MD, 663 const MethodVFTableLocation &ML); 664 665 llvm::Constant *EmitMemberDataPointer(const CXXRecordDecl *RD, 666 CharUnits offset); 667 668 public: 669 llvm::Type *ConvertMemberPointerType(const MemberPointerType *MPT) override; 670 671 bool isZeroInitializable(const MemberPointerType *MPT) override; 672 673 bool isMemberPointerConvertible(const MemberPointerType *MPT) const override { 674 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl(); 675 return RD->hasAttr<MSInheritanceAttr>(); 676 } 677 678 llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT) override; 679 680 llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT, 681 CharUnits offset) override; 682 llvm::Constant *EmitMemberFunctionPointer(const CXXMethodDecl *MD) override; 683 llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT) override; 684 685 llvm::Value *EmitMemberPointerComparison(CodeGenFunction &CGF, 686 llvm::Value *L, 687 llvm::Value *R, 688 const MemberPointerType *MPT, 689 bool Inequality) override; 690 691 llvm::Value *EmitMemberPointerIsNotNull(CodeGenFunction &CGF, 692 llvm::Value *MemPtr, 693 const MemberPointerType *MPT) override; 694 695 llvm::Value * 696 EmitMemberDataPointerAddress(CodeGenFunction &CGF, const Expr *E, 697 Address Base, llvm::Value *MemPtr, 698 const MemberPointerType *MPT) override; 699 700 llvm::Value *EmitNonNullMemberPointerConversion( 701 const MemberPointerType *SrcTy, const MemberPointerType *DstTy, 702 CastKind CK, CastExpr::path_const_iterator PathBegin, 703 CastExpr::path_const_iterator PathEnd, llvm::Value *Src, 704 CGBuilderTy &Builder); 705 706 llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF, 707 const CastExpr *E, 708 llvm::Value *Src) override; 709 710 llvm::Constant *EmitMemberPointerConversion(const CastExpr *E, 711 llvm::Constant *Src) override; 712 713 llvm::Constant *EmitMemberPointerConversion( 714 const MemberPointerType *SrcTy, const MemberPointerType *DstTy, 715 CastKind CK, CastExpr::path_const_iterator PathBegin, 716 CastExpr::path_const_iterator PathEnd, llvm::Constant *Src); 717 718 CGCallee 719 EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF, const Expr *E, 720 Address This, llvm::Value *&ThisPtrForCall, 721 llvm::Value *MemPtr, 722 const MemberPointerType *MPT) override; 723 724 void emitCXXStructor(GlobalDecl GD) override; 725 726 llvm::StructType *getCatchableTypeType() { 727 if (CatchableTypeType) 728 return CatchableTypeType; 729 llvm::Type *FieldTypes[] = { 730 CGM.IntTy, // Flags 731 getImageRelativeType(CGM.Int8PtrTy), // TypeDescriptor 732 CGM.IntTy, // NonVirtualAdjustment 733 CGM.IntTy, // OffsetToVBPtr 734 CGM.IntTy, // VBTableIndex 735 CGM.IntTy, // Size 736 getImageRelativeType(CGM.Int8PtrTy) // CopyCtor 737 }; 738 CatchableTypeType = llvm::StructType::create( 739 CGM.getLLVMContext(), FieldTypes, "eh.CatchableType"); 740 return CatchableTypeType; 741 } 742 743 llvm::StructType *getCatchableTypeArrayType(uint32_t NumEntries) { 744 llvm::StructType *&CatchableTypeArrayType = 745 CatchableTypeArrayTypeMap[NumEntries]; 746 if (CatchableTypeArrayType) 747 return CatchableTypeArrayType; 748 749 llvm::SmallString<23> CTATypeName("eh.CatchableTypeArray."); 750 CTATypeName += llvm::utostr(NumEntries); 751 llvm::Type *CTType = 752 getImageRelativeType(getCatchableTypeType()->getPointerTo()); 753 llvm::Type *FieldTypes[] = { 754 CGM.IntTy, // NumEntries 755 llvm::ArrayType::get(CTType, NumEntries) // CatchableTypes 756 }; 757 CatchableTypeArrayType = 758 llvm::StructType::create(CGM.getLLVMContext(), FieldTypes, CTATypeName); 759 return CatchableTypeArrayType; 760 } 761 762 llvm::StructType *getThrowInfoType() { 763 if (ThrowInfoType) 764 return ThrowInfoType; 765 llvm::Type *FieldTypes[] = { 766 CGM.IntTy, // Flags 767 getImageRelativeType(CGM.Int8PtrTy), // CleanupFn 768 getImageRelativeType(CGM.Int8PtrTy), // ForwardCompat 769 getImageRelativeType(CGM.Int8PtrTy) // CatchableTypeArray 770 }; 771 ThrowInfoType = llvm::StructType::create(CGM.getLLVMContext(), FieldTypes, 772 "eh.ThrowInfo"); 773 return ThrowInfoType; 774 } 775 776 llvm::FunctionCallee getThrowFn() { 777 // _CxxThrowException is passed an exception object and a ThrowInfo object 778 // which describes the exception. 779 llvm::Type *Args[] = {CGM.Int8PtrTy, getThrowInfoType()->getPointerTo()}; 780 llvm::FunctionType *FTy = 781 llvm::FunctionType::get(CGM.VoidTy, Args, /*isVarArg=*/false); 782 llvm::FunctionCallee Throw = 783 CGM.CreateRuntimeFunction(FTy, "_CxxThrowException"); 784 // _CxxThrowException is stdcall on 32-bit x86 platforms. 785 if (CGM.getTarget().getTriple().getArch() == llvm::Triple::x86) { 786 if (auto *Fn = dyn_cast<llvm::Function>(Throw.getCallee())) 787 Fn->setCallingConv(llvm::CallingConv::X86_StdCall); 788 } 789 return Throw; 790 } 791 792 llvm::Function *getAddrOfCXXCtorClosure(const CXXConstructorDecl *CD, 793 CXXCtorType CT); 794 795 llvm::Constant *getCatchableType(QualType T, 796 uint32_t NVOffset = 0, 797 int32_t VBPtrOffset = -1, 798 uint32_t VBIndex = 0); 799 800 llvm::GlobalVariable *getCatchableTypeArray(QualType T); 801 802 llvm::GlobalVariable *getThrowInfo(QualType T) override; 803 804 std::pair<llvm::Value *, const CXXRecordDecl *> 805 LoadVTablePtr(CodeGenFunction &CGF, Address This, 806 const CXXRecordDecl *RD) override; 807 808 bool 809 isPermittedToBeHomogeneousAggregate(const CXXRecordDecl *RD) const override; 810 811 private: 812 typedef std::pair<const CXXRecordDecl *, CharUnits> VFTableIdTy; 813 typedef llvm::DenseMap<VFTableIdTy, llvm::GlobalVariable *> VTablesMapTy; 814 typedef llvm::DenseMap<VFTableIdTy, llvm::GlobalValue *> VFTablesMapTy; 815 /// All the vftables that have been referenced. 816 VFTablesMapTy VFTablesMap; 817 VTablesMapTy VTablesMap; 818 819 /// This set holds the record decls we've deferred vtable emission for. 820 llvm::SmallPtrSet<const CXXRecordDecl *, 4> DeferredVFTables; 821 822 823 /// All the vbtables which have been referenced. 824 llvm::DenseMap<const CXXRecordDecl *, VBTableGlobals> VBTablesMap; 825 826 /// Info on the global variable used to guard initialization of static locals. 827 /// The BitIndex field is only used for externally invisible declarations. 828 struct GuardInfo { 829 GuardInfo() = default; 830 llvm::GlobalVariable *Guard = nullptr; 831 unsigned BitIndex = 0; 832 }; 833 834 /// Map from DeclContext to the current guard variable. We assume that the 835 /// AST is visited in source code order. 836 llvm::DenseMap<const DeclContext *, GuardInfo> GuardVariableMap; 837 llvm::DenseMap<const DeclContext *, GuardInfo> ThreadLocalGuardVariableMap; 838 llvm::DenseMap<const DeclContext *, unsigned> ThreadSafeGuardNumMap; 839 840 llvm::DenseMap<size_t, llvm::StructType *> TypeDescriptorTypeMap; 841 llvm::StructType *BaseClassDescriptorType; 842 llvm::StructType *ClassHierarchyDescriptorType; 843 llvm::StructType *CompleteObjectLocatorType; 844 845 llvm::DenseMap<QualType, llvm::GlobalVariable *> CatchableTypeArrays; 846 847 llvm::StructType *CatchableTypeType; 848 llvm::DenseMap<uint32_t, llvm::StructType *> CatchableTypeArrayTypeMap; 849 llvm::StructType *ThrowInfoType; 850 }; 851 852 } 853 854 CGCXXABI::RecordArgABI 855 MicrosoftCXXABI::getRecordArgABI(const CXXRecordDecl *RD) const { 856 // Use the default C calling convention rules for things that can be passed in 857 // registers, i.e. non-trivially copyable records or records marked with 858 // [[trivial_abi]]. 859 if (RD->canPassInRegisters()) 860 return RAA_Default; 861 862 switch (CGM.getTarget().getTriple().getArch()) { 863 default: 864 // FIXME: Implement for other architectures. 865 return RAA_Indirect; 866 867 case llvm::Triple::thumb: 868 // Pass things indirectly for now because it is simple. 869 // FIXME: This is incompatible with MSVC for arguments with a dtor and no 870 // copy ctor. 871 return RAA_Indirect; 872 873 case llvm::Triple::x86: { 874 // If the argument has *required* alignment greater than four bytes, pass 875 // it indirectly. Prior to MSVC version 19.14, passing overaligned 876 // arguments was not supported and resulted in a compiler error. In 19.14 877 // and later versions, such arguments are now passed indirectly. 878 TypeInfo Info = getContext().getTypeInfo(RD->getTypeForDecl()); 879 if (Info.isAlignRequired() && Info.Align > 4) 880 return RAA_Indirect; 881 882 // If C++ prohibits us from making a copy, construct the arguments directly 883 // into argument memory. 884 return RAA_DirectInMemory; 885 } 886 887 case llvm::Triple::x86_64: 888 case llvm::Triple::aarch64: 889 return RAA_Indirect; 890 } 891 892 llvm_unreachable("invalid enum"); 893 } 894 895 void MicrosoftCXXABI::emitVirtualObjectDelete(CodeGenFunction &CGF, 896 const CXXDeleteExpr *DE, 897 Address Ptr, 898 QualType ElementType, 899 const CXXDestructorDecl *Dtor) { 900 // FIXME: Provide a source location here even though there's no 901 // CXXMemberCallExpr for dtor call. 902 bool UseGlobalDelete = DE->isGlobalDelete(); 903 CXXDtorType DtorType = UseGlobalDelete ? Dtor_Complete : Dtor_Deleting; 904 llvm::Value *MDThis = EmitVirtualDestructorCall(CGF, Dtor, DtorType, Ptr, DE); 905 if (UseGlobalDelete) 906 CGF.EmitDeleteCall(DE->getOperatorDelete(), MDThis, ElementType); 907 } 908 909 void MicrosoftCXXABI::emitRethrow(CodeGenFunction &CGF, bool isNoReturn) { 910 llvm::Value *Args[] = { 911 llvm::ConstantPointerNull::get(CGM.Int8PtrTy), 912 llvm::ConstantPointerNull::get(getThrowInfoType()->getPointerTo())}; 913 llvm::FunctionCallee Fn = getThrowFn(); 914 if (isNoReturn) 915 CGF.EmitNoreturnRuntimeCallOrInvoke(Fn, Args); 916 else 917 CGF.EmitRuntimeCallOrInvoke(Fn, Args); 918 } 919 920 void MicrosoftCXXABI::emitBeginCatch(CodeGenFunction &CGF, 921 const CXXCatchStmt *S) { 922 // In the MS ABI, the runtime handles the copy, and the catch handler is 923 // responsible for destruction. 924 VarDecl *CatchParam = S->getExceptionDecl(); 925 llvm::BasicBlock *CatchPadBB = CGF.Builder.GetInsertBlock(); 926 llvm::CatchPadInst *CPI = 927 cast<llvm::CatchPadInst>(CatchPadBB->getFirstNonPHI()); 928 CGF.CurrentFuncletPad = CPI; 929 930 // If this is a catch-all or the catch parameter is unnamed, we don't need to 931 // emit an alloca to the object. 932 if (!CatchParam || !CatchParam->getDeclName()) { 933 CGF.EHStack.pushCleanup<CatchRetScope>(NormalCleanup, CPI); 934 return; 935 } 936 937 CodeGenFunction::AutoVarEmission var = CGF.EmitAutoVarAlloca(*CatchParam); 938 CPI->setArgOperand(2, var.getObjectAddress(CGF).emitRawPointer(CGF)); 939 CGF.EHStack.pushCleanup<CatchRetScope>(NormalCleanup, CPI); 940 CGF.EmitAutoVarCleanups(var); 941 } 942 943 /// We need to perform a generic polymorphic operation (like a typeid 944 /// or a cast), which requires an object with a vfptr. Adjust the 945 /// address to point to an object with a vfptr. 946 std::tuple<Address, llvm::Value *, const CXXRecordDecl *> 947 MicrosoftCXXABI::performBaseAdjustment(CodeGenFunction &CGF, Address Value, 948 QualType SrcRecordTy) { 949 Value = Value.withElementType(CGF.Int8Ty); 950 const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl(); 951 const ASTContext &Context = getContext(); 952 953 // If the class itself has a vfptr, great. This check implicitly 954 // covers non-virtual base subobjects: a class with its own virtual 955 // functions would be a candidate to be a primary base. 956 if (Context.getASTRecordLayout(SrcDecl).hasExtendableVFPtr()) 957 return std::make_tuple(Value, llvm::ConstantInt::get(CGF.Int32Ty, 0), 958 SrcDecl); 959 960 // Okay, one of the vbases must have a vfptr, or else this isn't 961 // actually a polymorphic class. 962 const CXXRecordDecl *PolymorphicBase = nullptr; 963 for (auto &Base : SrcDecl->vbases()) { 964 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl(); 965 if (Context.getASTRecordLayout(BaseDecl).hasExtendableVFPtr()) { 966 PolymorphicBase = BaseDecl; 967 break; 968 } 969 } 970 assert(PolymorphicBase && "polymorphic class has no apparent vfptr?"); 971 972 llvm::Value *Offset = 973 GetVirtualBaseClassOffset(CGF, Value, SrcDecl, PolymorphicBase); 974 llvm::Value *Ptr = CGF.Builder.CreateInBoundsGEP( 975 Value.getElementType(), Value.emitRawPointer(CGF), Offset); 976 CharUnits VBaseAlign = 977 CGF.CGM.getVBaseAlignment(Value.getAlignment(), SrcDecl, PolymorphicBase); 978 return std::make_tuple(Address(Ptr, CGF.Int8Ty, VBaseAlign), Offset, 979 PolymorphicBase); 980 } 981 982 bool MicrosoftCXXABI::shouldTypeidBeNullChecked(QualType SrcRecordTy) { 983 const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl(); 984 return !getContext().getASTRecordLayout(SrcDecl).hasExtendableVFPtr(); 985 } 986 987 static llvm::CallBase *emitRTtypeidCall(CodeGenFunction &CGF, 988 llvm::Value *Argument) { 989 llvm::Type *ArgTypes[] = {CGF.Int8PtrTy}; 990 llvm::FunctionType *FTy = 991 llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false); 992 llvm::Value *Args[] = {Argument}; 993 llvm::FunctionCallee Fn = CGF.CGM.CreateRuntimeFunction(FTy, "__RTtypeid"); 994 return CGF.EmitRuntimeCallOrInvoke(Fn, Args); 995 } 996 997 void MicrosoftCXXABI::EmitBadTypeidCall(CodeGenFunction &CGF) { 998 llvm::CallBase *Call = 999 emitRTtypeidCall(CGF, llvm::Constant::getNullValue(CGM.VoidPtrTy)); 1000 Call->setDoesNotReturn(); 1001 CGF.Builder.CreateUnreachable(); 1002 } 1003 1004 llvm::Value *MicrosoftCXXABI::EmitTypeid(CodeGenFunction &CGF, 1005 QualType SrcRecordTy, 1006 Address ThisPtr, 1007 llvm::Type *StdTypeInfoPtrTy) { 1008 std::tie(ThisPtr, std::ignore, std::ignore) = 1009 performBaseAdjustment(CGF, ThisPtr, SrcRecordTy); 1010 llvm::CallBase *Typeid = emitRTtypeidCall(CGF, ThisPtr.emitRawPointer(CGF)); 1011 return CGF.Builder.CreateBitCast(Typeid, StdTypeInfoPtrTy); 1012 } 1013 1014 bool MicrosoftCXXABI::shouldDynamicCastCallBeNullChecked(bool SrcIsPtr, 1015 QualType SrcRecordTy) { 1016 const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl(); 1017 return SrcIsPtr && 1018 !getContext().getASTRecordLayout(SrcDecl).hasExtendableVFPtr(); 1019 } 1020 1021 llvm::Value *MicrosoftCXXABI::emitDynamicCastCall( 1022 CodeGenFunction &CGF, Address This, QualType SrcRecordTy, QualType DestTy, 1023 QualType DestRecordTy, llvm::BasicBlock *CastEnd) { 1024 llvm::Value *SrcRTTI = 1025 CGF.CGM.GetAddrOfRTTIDescriptor(SrcRecordTy.getUnqualifiedType()); 1026 llvm::Value *DestRTTI = 1027 CGF.CGM.GetAddrOfRTTIDescriptor(DestRecordTy.getUnqualifiedType()); 1028 1029 llvm::Value *Offset; 1030 std::tie(This, Offset, std::ignore) = 1031 performBaseAdjustment(CGF, This, SrcRecordTy); 1032 llvm::Value *ThisPtr = This.emitRawPointer(CGF); 1033 Offset = CGF.Builder.CreateTrunc(Offset, CGF.Int32Ty); 1034 1035 // PVOID __RTDynamicCast( 1036 // PVOID inptr, 1037 // LONG VfDelta, 1038 // PVOID SrcType, 1039 // PVOID TargetType, 1040 // BOOL isReference) 1041 llvm::Type *ArgTypes[] = {CGF.Int8PtrTy, CGF.Int32Ty, CGF.Int8PtrTy, 1042 CGF.Int8PtrTy, CGF.Int32Ty}; 1043 llvm::FunctionCallee Function = CGF.CGM.CreateRuntimeFunction( 1044 llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false), 1045 "__RTDynamicCast"); 1046 llvm::Value *Args[] = { 1047 ThisPtr, Offset, SrcRTTI, DestRTTI, 1048 llvm::ConstantInt::get(CGF.Int32Ty, DestTy->isReferenceType())}; 1049 return CGF.EmitRuntimeCallOrInvoke(Function, Args); 1050 } 1051 1052 llvm::Value *MicrosoftCXXABI::emitDynamicCastToVoid(CodeGenFunction &CGF, 1053 Address Value, 1054 QualType SrcRecordTy) { 1055 std::tie(Value, std::ignore, std::ignore) = 1056 performBaseAdjustment(CGF, Value, SrcRecordTy); 1057 1058 // PVOID __RTCastToVoid( 1059 // PVOID inptr) 1060 llvm::Type *ArgTypes[] = {CGF.Int8PtrTy}; 1061 llvm::FunctionCallee Function = CGF.CGM.CreateRuntimeFunction( 1062 llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false), 1063 "__RTCastToVoid"); 1064 llvm::Value *Args[] = {Value.emitRawPointer(CGF)}; 1065 return CGF.EmitRuntimeCall(Function, Args); 1066 } 1067 1068 bool MicrosoftCXXABI::EmitBadCastCall(CodeGenFunction &CGF) { 1069 return false; 1070 } 1071 1072 llvm::Value *MicrosoftCXXABI::GetVirtualBaseClassOffset( 1073 CodeGenFunction &CGF, Address This, const CXXRecordDecl *ClassDecl, 1074 const CXXRecordDecl *BaseClassDecl) { 1075 const ASTContext &Context = getContext(); 1076 int64_t VBPtrChars = 1077 Context.getASTRecordLayout(ClassDecl).getVBPtrOffset().getQuantity(); 1078 llvm::Value *VBPtrOffset = llvm::ConstantInt::get(CGM.PtrDiffTy, VBPtrChars); 1079 CharUnits IntSize = Context.getTypeSizeInChars(Context.IntTy); 1080 CharUnits VBTableChars = 1081 IntSize * 1082 CGM.getMicrosoftVTableContext().getVBTableIndex(ClassDecl, BaseClassDecl); 1083 llvm::Value *VBTableOffset = 1084 llvm::ConstantInt::get(CGM.IntTy, VBTableChars.getQuantity()); 1085 1086 llvm::Value *VBPtrToNewBase = 1087 GetVBaseOffsetFromVBPtr(CGF, This, VBPtrOffset, VBTableOffset); 1088 VBPtrToNewBase = 1089 CGF.Builder.CreateSExtOrBitCast(VBPtrToNewBase, CGM.PtrDiffTy); 1090 return CGF.Builder.CreateNSWAdd(VBPtrOffset, VBPtrToNewBase); 1091 } 1092 1093 bool MicrosoftCXXABI::HasThisReturn(GlobalDecl GD) const { 1094 return isa<CXXConstructorDecl>(GD.getDecl()); 1095 } 1096 1097 static bool isDeletingDtor(GlobalDecl GD) { 1098 return isa<CXXDestructorDecl>(GD.getDecl()) && 1099 GD.getDtorType() == Dtor_Deleting; 1100 } 1101 1102 bool MicrosoftCXXABI::hasMostDerivedReturn(GlobalDecl GD) const { 1103 return isDeletingDtor(GD); 1104 } 1105 1106 static bool isTrivialForMSVC(const CXXRecordDecl *RD, QualType Ty, 1107 CodeGenModule &CGM) { 1108 // On AArch64, HVAs that can be passed in registers can also be returned 1109 // in registers. (Note this is using the MSVC definition of an HVA; see 1110 // isPermittedToBeHomogeneousAggregate().) 1111 const Type *Base = nullptr; 1112 uint64_t NumElts = 0; 1113 if (CGM.getTarget().getTriple().isAArch64() && 1114 CGM.getABIInfo().isHomogeneousAggregate(Ty, Base, NumElts) && 1115 isa<VectorType>(Base)) { 1116 return true; 1117 } 1118 1119 // We use the C++14 definition of an aggregate, so we also 1120 // check for: 1121 // No private or protected non static data members. 1122 // No base classes 1123 // No virtual functions 1124 // Additionally, we need to ensure that there is a trivial copy assignment 1125 // operator, a trivial destructor, no user-provided constructors and no 1126 // deleted copy assignment operator. 1127 1128 // We need to cover two cases when checking for a deleted copy assignment 1129 // operator. 1130 // 1131 // struct S { int& r; }; 1132 // The above will have an implicit copy assignment operator that is deleted 1133 // and there will not be a `CXXMethodDecl` for the copy assignment operator. 1134 // This is handled by the `needsImplicitCopyAssignment()` check below. 1135 // 1136 // struct S { S& operator=(const S&) = delete; int i; }; 1137 // The above will not have an implicit copy assignment operator that is 1138 // deleted but there is a deleted `CXXMethodDecl` for the declared copy 1139 // assignment operator. This is handled by the `isDeleted()` check below. 1140 1141 if (RD->hasProtectedFields() || RD->hasPrivateFields()) 1142 return false; 1143 if (RD->getNumBases() > 0) 1144 return false; 1145 if (RD->isPolymorphic()) 1146 return false; 1147 if (RD->hasNonTrivialCopyAssignment()) 1148 return false; 1149 if (RD->needsImplicitCopyAssignment() && !RD->hasSimpleCopyAssignment()) 1150 return false; 1151 for (const Decl *D : RD->decls()) { 1152 if (auto *Ctor = dyn_cast<CXXConstructorDecl>(D)) { 1153 if (Ctor->isUserProvided()) 1154 return false; 1155 } else if (auto *Template = dyn_cast<FunctionTemplateDecl>(D)) { 1156 if (isa<CXXConstructorDecl>(Template->getTemplatedDecl())) 1157 return false; 1158 } else if (auto *MethodDecl = dyn_cast<CXXMethodDecl>(D)) { 1159 if (MethodDecl->isCopyAssignmentOperator() && MethodDecl->isDeleted()) 1160 return false; 1161 } 1162 } 1163 if (RD->hasNonTrivialDestructor()) 1164 return false; 1165 return true; 1166 } 1167 1168 bool MicrosoftCXXABI::classifyReturnType(CGFunctionInfo &FI) const { 1169 const CXXRecordDecl *RD = FI.getReturnType()->getAsCXXRecordDecl(); 1170 if (!RD) 1171 return false; 1172 1173 bool isTrivialForABI = RD->canPassInRegisters() && 1174 isTrivialForMSVC(RD, FI.getReturnType(), CGM); 1175 1176 // MSVC always returns structs indirectly from C++ instance methods. 1177 bool isIndirectReturn = !isTrivialForABI || FI.isInstanceMethod(); 1178 1179 if (isIndirectReturn) { 1180 CharUnits Align = CGM.getContext().getTypeAlignInChars(FI.getReturnType()); 1181 FI.getReturnInfo() = ABIArgInfo::getIndirect(Align, /*ByVal=*/false); 1182 1183 // MSVC always passes `this` before the `sret` parameter. 1184 FI.getReturnInfo().setSRetAfterThis(FI.isInstanceMethod()); 1185 1186 // On AArch64, use the `inreg` attribute if the object is considered to not 1187 // be trivially copyable, or if this is an instance method struct return. 1188 FI.getReturnInfo().setInReg(CGM.getTarget().getTriple().isAArch64()); 1189 1190 return true; 1191 } 1192 1193 // Otherwise, use the C ABI rules. 1194 return false; 1195 } 1196 1197 llvm::BasicBlock * 1198 MicrosoftCXXABI::EmitCtorCompleteObjectHandler(CodeGenFunction &CGF, 1199 const CXXRecordDecl *RD) { 1200 llvm::Value *IsMostDerivedClass = getStructorImplicitParamValue(CGF); 1201 assert(IsMostDerivedClass && 1202 "ctor for a class with virtual bases must have an implicit parameter"); 1203 llvm::Value *IsCompleteObject = 1204 CGF.Builder.CreateIsNotNull(IsMostDerivedClass, "is_complete_object"); 1205 1206 llvm::BasicBlock *CallVbaseCtorsBB = CGF.createBasicBlock("ctor.init_vbases"); 1207 llvm::BasicBlock *SkipVbaseCtorsBB = CGF.createBasicBlock("ctor.skip_vbases"); 1208 CGF.Builder.CreateCondBr(IsCompleteObject, 1209 CallVbaseCtorsBB, SkipVbaseCtorsBB); 1210 1211 CGF.EmitBlock(CallVbaseCtorsBB); 1212 1213 // Fill in the vbtable pointers here. 1214 EmitVBPtrStores(CGF, RD); 1215 1216 // CGF will put the base ctor calls in this basic block for us later. 1217 1218 return SkipVbaseCtorsBB; 1219 } 1220 1221 llvm::BasicBlock * 1222 MicrosoftCXXABI::EmitDtorCompleteObjectHandler(CodeGenFunction &CGF) { 1223 llvm::Value *IsMostDerivedClass = getStructorImplicitParamValue(CGF); 1224 assert(IsMostDerivedClass && 1225 "ctor for a class with virtual bases must have an implicit parameter"); 1226 llvm::Value *IsCompleteObject = 1227 CGF.Builder.CreateIsNotNull(IsMostDerivedClass, "is_complete_object"); 1228 1229 llvm::BasicBlock *CallVbaseDtorsBB = CGF.createBasicBlock("Dtor.dtor_vbases"); 1230 llvm::BasicBlock *SkipVbaseDtorsBB = CGF.createBasicBlock("Dtor.skip_vbases"); 1231 CGF.Builder.CreateCondBr(IsCompleteObject, 1232 CallVbaseDtorsBB, SkipVbaseDtorsBB); 1233 1234 CGF.EmitBlock(CallVbaseDtorsBB); 1235 // CGF will put the base dtor calls in this basic block for us later. 1236 1237 return SkipVbaseDtorsBB; 1238 } 1239 1240 void MicrosoftCXXABI::initializeHiddenVirtualInheritanceMembers( 1241 CodeGenFunction &CGF, const CXXRecordDecl *RD) { 1242 // In most cases, an override for a vbase virtual method can adjust 1243 // the "this" parameter by applying a constant offset. 1244 // However, this is not enough while a constructor or a destructor of some 1245 // class X is being executed if all the following conditions are met: 1246 // - X has virtual bases, (1) 1247 // - X overrides a virtual method M of a vbase Y, (2) 1248 // - X itself is a vbase of the most derived class. 1249 // 1250 // If (1) and (2) are true, the vtorDisp for vbase Y is a hidden member of X 1251 // which holds the extra amount of "this" adjustment we must do when we use 1252 // the X vftables (i.e. during X ctor or dtor). 1253 // Outside the ctors and dtors, the values of vtorDisps are zero. 1254 1255 const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD); 1256 typedef ASTRecordLayout::VBaseOffsetsMapTy VBOffsets; 1257 const VBOffsets &VBaseMap = Layout.getVBaseOffsetsMap(); 1258 CGBuilderTy &Builder = CGF.Builder; 1259 1260 llvm::Value *Int8This = nullptr; // Initialize lazily. 1261 1262 for (const CXXBaseSpecifier &S : RD->vbases()) { 1263 const CXXRecordDecl *VBase = S.getType()->getAsCXXRecordDecl(); 1264 auto I = VBaseMap.find(VBase); 1265 assert(I != VBaseMap.end()); 1266 if (!I->second.hasVtorDisp()) 1267 continue; 1268 1269 llvm::Value *VBaseOffset = 1270 GetVirtualBaseClassOffset(CGF, getThisAddress(CGF), RD, VBase); 1271 uint64_t ConstantVBaseOffset = I->second.VBaseOffset.getQuantity(); 1272 1273 // vtorDisp_for_vbase = vbptr[vbase_idx] - offsetof(RD, vbase). 1274 llvm::Value *VtorDispValue = Builder.CreateSub( 1275 VBaseOffset, llvm::ConstantInt::get(CGM.PtrDiffTy, ConstantVBaseOffset), 1276 "vtordisp.value"); 1277 VtorDispValue = Builder.CreateTruncOrBitCast(VtorDispValue, CGF.Int32Ty); 1278 1279 if (!Int8This) 1280 Int8This = getThisValue(CGF); 1281 1282 llvm::Value *VtorDispPtr = 1283 Builder.CreateInBoundsGEP(CGF.Int8Ty, Int8This, VBaseOffset); 1284 // vtorDisp is always the 32-bits before the vbase in the class layout. 1285 VtorDispPtr = Builder.CreateConstGEP1_32(CGF.Int8Ty, VtorDispPtr, -4); 1286 1287 Builder.CreateAlignedStore(VtorDispValue, VtorDispPtr, 1288 CharUnits::fromQuantity(4)); 1289 } 1290 } 1291 1292 static bool hasDefaultCXXMethodCC(ASTContext &Context, 1293 const CXXMethodDecl *MD) { 1294 CallingConv ExpectedCallingConv = Context.getDefaultCallingConvention( 1295 /*IsVariadic=*/false, /*IsCXXMethod=*/true); 1296 CallingConv ActualCallingConv = 1297 MD->getType()->castAs<FunctionProtoType>()->getCallConv(); 1298 return ExpectedCallingConv == ActualCallingConv; 1299 } 1300 1301 void MicrosoftCXXABI::EmitCXXConstructors(const CXXConstructorDecl *D) { 1302 // There's only one constructor type in this ABI. 1303 CGM.EmitGlobal(GlobalDecl(D, Ctor_Complete)); 1304 1305 // Exported default constructors either have a simple call-site where they use 1306 // the typical calling convention and have a single 'this' pointer for an 1307 // argument -or- they get a wrapper function which appropriately thunks to the 1308 // real default constructor. This thunk is the default constructor closure. 1309 if (D->hasAttr<DLLExportAttr>() && D->isDefaultConstructor() && 1310 D->isDefined()) { 1311 if (!hasDefaultCXXMethodCC(getContext(), D) || D->getNumParams() != 0) { 1312 llvm::Function *Fn = getAddrOfCXXCtorClosure(D, Ctor_DefaultClosure); 1313 Fn->setLinkage(llvm::GlobalValue::WeakODRLinkage); 1314 CGM.setGVProperties(Fn, D); 1315 } 1316 } 1317 } 1318 1319 void MicrosoftCXXABI::EmitVBPtrStores(CodeGenFunction &CGF, 1320 const CXXRecordDecl *RD) { 1321 Address This = getThisAddress(CGF); 1322 This = This.withElementType(CGM.Int8Ty); 1323 const ASTContext &Context = getContext(); 1324 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); 1325 1326 const VBTableGlobals &VBGlobals = enumerateVBTables(RD); 1327 for (unsigned I = 0, E = VBGlobals.VBTables->size(); I != E; ++I) { 1328 const std::unique_ptr<VPtrInfo> &VBT = (*VBGlobals.VBTables)[I]; 1329 llvm::GlobalVariable *GV = VBGlobals.Globals[I]; 1330 const ASTRecordLayout &SubobjectLayout = 1331 Context.getASTRecordLayout(VBT->IntroducingObject); 1332 CharUnits Offs = VBT->NonVirtualOffset; 1333 Offs += SubobjectLayout.getVBPtrOffset(); 1334 if (VBT->getVBaseWithVPtr()) 1335 Offs += Layout.getVBaseClassOffset(VBT->getVBaseWithVPtr()); 1336 Address VBPtr = CGF.Builder.CreateConstInBoundsByteGEP(This, Offs); 1337 llvm::Value *GVPtr = 1338 CGF.Builder.CreateConstInBoundsGEP2_32(GV->getValueType(), GV, 0, 0); 1339 VBPtr = VBPtr.withElementType(GVPtr->getType()); 1340 CGF.Builder.CreateStore(GVPtr, VBPtr); 1341 } 1342 } 1343 1344 CGCXXABI::AddedStructorArgCounts 1345 MicrosoftCXXABI::buildStructorSignature(GlobalDecl GD, 1346 SmallVectorImpl<CanQualType> &ArgTys) { 1347 AddedStructorArgCounts Added; 1348 // TODO: 'for base' flag 1349 if (isa<CXXDestructorDecl>(GD.getDecl()) && 1350 GD.getDtorType() == Dtor_Deleting) { 1351 // The scalar deleting destructor takes an implicit int parameter. 1352 ArgTys.push_back(getContext().IntTy); 1353 ++Added.Suffix; 1354 } 1355 auto *CD = dyn_cast<CXXConstructorDecl>(GD.getDecl()); 1356 if (!CD) 1357 return Added; 1358 1359 // All parameters are already in place except is_most_derived, which goes 1360 // after 'this' if it's variadic and last if it's not. 1361 1362 const CXXRecordDecl *Class = CD->getParent(); 1363 const FunctionProtoType *FPT = CD->getType()->castAs<FunctionProtoType>(); 1364 if (Class->getNumVBases()) { 1365 if (FPT->isVariadic()) { 1366 ArgTys.insert(ArgTys.begin() + 1, getContext().IntTy); 1367 ++Added.Prefix; 1368 } else { 1369 ArgTys.push_back(getContext().IntTy); 1370 ++Added.Suffix; 1371 } 1372 } 1373 1374 return Added; 1375 } 1376 1377 void MicrosoftCXXABI::setCXXDestructorDLLStorage(llvm::GlobalValue *GV, 1378 const CXXDestructorDecl *Dtor, 1379 CXXDtorType DT) const { 1380 // Deleting destructor variants are never imported or exported. Give them the 1381 // default storage class. 1382 if (DT == Dtor_Deleting) { 1383 GV->setDLLStorageClass(llvm::GlobalValue::DefaultStorageClass); 1384 } else { 1385 const NamedDecl *ND = Dtor; 1386 CGM.setDLLImportDLLExport(GV, ND); 1387 } 1388 } 1389 1390 llvm::GlobalValue::LinkageTypes MicrosoftCXXABI::getCXXDestructorLinkage( 1391 GVALinkage Linkage, const CXXDestructorDecl *Dtor, CXXDtorType DT) const { 1392 // Internal things are always internal, regardless of attributes. After this, 1393 // we know the thunk is externally visible. 1394 if (Linkage == GVA_Internal) 1395 return llvm::GlobalValue::InternalLinkage; 1396 1397 switch (DT) { 1398 case Dtor_Base: 1399 // The base destructor most closely tracks the user-declared constructor, so 1400 // we delegate back to the normal declarator case. 1401 return CGM.getLLVMLinkageForDeclarator(Dtor, Linkage); 1402 case Dtor_Complete: 1403 // The complete destructor is like an inline function, but it may be 1404 // imported and therefore must be exported as well. This requires changing 1405 // the linkage if a DLL attribute is present. 1406 if (Dtor->hasAttr<DLLExportAttr>()) 1407 return llvm::GlobalValue::WeakODRLinkage; 1408 if (Dtor->hasAttr<DLLImportAttr>()) 1409 return llvm::GlobalValue::AvailableExternallyLinkage; 1410 return llvm::GlobalValue::LinkOnceODRLinkage; 1411 case Dtor_Deleting: 1412 // Deleting destructors are like inline functions. They have vague linkage 1413 // and are emitted everywhere they are used. They are internal if the class 1414 // is internal. 1415 return llvm::GlobalValue::LinkOnceODRLinkage; 1416 case Dtor_Comdat: 1417 llvm_unreachable("MS C++ ABI does not support comdat dtors"); 1418 } 1419 llvm_unreachable("invalid dtor type"); 1420 } 1421 1422 void MicrosoftCXXABI::EmitCXXDestructors(const CXXDestructorDecl *D) { 1423 // The TU defining a dtor is only guaranteed to emit a base destructor. All 1424 // other destructor variants are delegating thunks. 1425 CGM.EmitGlobal(GlobalDecl(D, Dtor_Base)); 1426 1427 // If the class is dllexported, emit the complete (vbase) destructor wherever 1428 // the base dtor is emitted. 1429 // FIXME: To match MSVC, this should only be done when the class is exported 1430 // with -fdllexport-inlines enabled. 1431 if (D->getParent()->getNumVBases() > 0 && D->hasAttr<DLLExportAttr>()) 1432 CGM.EmitGlobal(GlobalDecl(D, Dtor_Complete)); 1433 } 1434 1435 CharUnits 1436 MicrosoftCXXABI::getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD) { 1437 const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); 1438 1439 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) { 1440 // Complete destructors take a pointer to the complete object as a 1441 // parameter, thus don't need this adjustment. 1442 if (GD.getDtorType() == Dtor_Complete) 1443 return CharUnits(); 1444 1445 // There's no Dtor_Base in vftable but it shares the this adjustment with 1446 // the deleting one, so look it up instead. 1447 GD = GlobalDecl(DD, Dtor_Deleting); 1448 } 1449 1450 MethodVFTableLocation ML = 1451 CGM.getMicrosoftVTableContext().getMethodVFTableLocation(GD); 1452 CharUnits Adjustment = ML.VFPtrOffset; 1453 1454 // Normal virtual instance methods need to adjust from the vfptr that first 1455 // defined the virtual method to the virtual base subobject, but destructors 1456 // do not. The vector deleting destructor thunk applies this adjustment for 1457 // us if necessary. 1458 if (isa<CXXDestructorDecl>(MD)) 1459 Adjustment = CharUnits::Zero(); 1460 1461 if (ML.VBase) { 1462 const ASTRecordLayout &DerivedLayout = 1463 getContext().getASTRecordLayout(MD->getParent()); 1464 Adjustment += DerivedLayout.getVBaseClassOffset(ML.VBase); 1465 } 1466 1467 return Adjustment; 1468 } 1469 1470 Address MicrosoftCXXABI::adjustThisArgumentForVirtualFunctionCall( 1471 CodeGenFunction &CGF, GlobalDecl GD, Address This, 1472 bool VirtualCall) { 1473 if (!VirtualCall) { 1474 // If the call of a virtual function is not virtual, we just have to 1475 // compensate for the adjustment the virtual function does in its prologue. 1476 CharUnits Adjustment = getVirtualFunctionPrologueThisAdjustment(GD); 1477 if (Adjustment.isZero()) 1478 return This; 1479 1480 This = This.withElementType(CGF.Int8Ty); 1481 assert(Adjustment.isPositive()); 1482 return CGF.Builder.CreateConstByteGEP(This, Adjustment); 1483 } 1484 1485 const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); 1486 1487 GlobalDecl LookupGD = GD; 1488 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) { 1489 // Complete dtors take a pointer to the complete object, 1490 // thus don't need adjustment. 1491 if (GD.getDtorType() == Dtor_Complete) 1492 return This; 1493 1494 // There's only Dtor_Deleting in vftable but it shares the this adjustment 1495 // with the base one, so look up the deleting one instead. 1496 LookupGD = GlobalDecl(DD, Dtor_Deleting); 1497 } 1498 MethodVFTableLocation ML = 1499 CGM.getMicrosoftVTableContext().getMethodVFTableLocation(LookupGD); 1500 1501 CharUnits StaticOffset = ML.VFPtrOffset; 1502 1503 // Base destructors expect 'this' to point to the beginning of the base 1504 // subobject, not the first vfptr that happens to contain the virtual dtor. 1505 // However, we still need to apply the virtual base adjustment. 1506 if (isa<CXXDestructorDecl>(MD) && GD.getDtorType() == Dtor_Base) 1507 StaticOffset = CharUnits::Zero(); 1508 1509 Address Result = This; 1510 if (ML.VBase) { 1511 Result = Result.withElementType(CGF.Int8Ty); 1512 1513 const CXXRecordDecl *Derived = MD->getParent(); 1514 const CXXRecordDecl *VBase = ML.VBase; 1515 llvm::Value *VBaseOffset = 1516 GetVirtualBaseClassOffset(CGF, Result, Derived, VBase); 1517 llvm::Value *VBasePtr = CGF.Builder.CreateInBoundsGEP( 1518 Result.getElementType(), Result.emitRawPointer(CGF), VBaseOffset); 1519 CharUnits VBaseAlign = 1520 CGF.CGM.getVBaseAlignment(Result.getAlignment(), Derived, VBase); 1521 Result = Address(VBasePtr, CGF.Int8Ty, VBaseAlign); 1522 } 1523 if (!StaticOffset.isZero()) { 1524 assert(StaticOffset.isPositive()); 1525 Result = Result.withElementType(CGF.Int8Ty); 1526 if (ML.VBase) { 1527 // Non-virtual adjustment might result in a pointer outside the allocated 1528 // object, e.g. if the final overrider class is laid out after the virtual 1529 // base that declares a method in the most derived class. 1530 // FIXME: Update the code that emits this adjustment in thunks prologues. 1531 Result = CGF.Builder.CreateConstByteGEP(Result, StaticOffset); 1532 } else { 1533 Result = CGF.Builder.CreateConstInBoundsByteGEP(Result, StaticOffset); 1534 } 1535 } 1536 return Result; 1537 } 1538 1539 void MicrosoftCXXABI::addImplicitStructorParams(CodeGenFunction &CGF, 1540 QualType &ResTy, 1541 FunctionArgList &Params) { 1542 ASTContext &Context = getContext(); 1543 const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl()); 1544 assert(isa<CXXConstructorDecl>(MD) || isa<CXXDestructorDecl>(MD)); 1545 if (isa<CXXConstructorDecl>(MD) && MD->getParent()->getNumVBases()) { 1546 auto *IsMostDerived = ImplicitParamDecl::Create( 1547 Context, /*DC=*/nullptr, CGF.CurGD.getDecl()->getLocation(), 1548 &Context.Idents.get("is_most_derived"), Context.IntTy, 1549 ImplicitParamKind::Other); 1550 // The 'most_derived' parameter goes second if the ctor is variadic and last 1551 // if it's not. Dtors can't be variadic. 1552 const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>(); 1553 if (FPT->isVariadic()) 1554 Params.insert(Params.begin() + 1, IsMostDerived); 1555 else 1556 Params.push_back(IsMostDerived); 1557 getStructorImplicitParamDecl(CGF) = IsMostDerived; 1558 } else if (isDeletingDtor(CGF.CurGD)) { 1559 auto *ShouldDelete = ImplicitParamDecl::Create( 1560 Context, /*DC=*/nullptr, CGF.CurGD.getDecl()->getLocation(), 1561 &Context.Idents.get("should_call_delete"), Context.IntTy, 1562 ImplicitParamKind::Other); 1563 Params.push_back(ShouldDelete); 1564 getStructorImplicitParamDecl(CGF) = ShouldDelete; 1565 } 1566 } 1567 1568 void MicrosoftCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) { 1569 // Naked functions have no prolog. 1570 if (CGF.CurFuncDecl && CGF.CurFuncDecl->hasAttr<NakedAttr>()) 1571 return; 1572 1573 // Overridden virtual methods of non-primary bases need to adjust the incoming 1574 // 'this' pointer in the prologue. In this hierarchy, C::b will subtract 1575 // sizeof(void*) to adjust from B* to C*: 1576 // struct A { virtual void a(); }; 1577 // struct B { virtual void b(); }; 1578 // struct C : A, B { virtual void b(); }; 1579 // 1580 // Leave the value stored in the 'this' alloca unadjusted, so that the 1581 // debugger sees the unadjusted value. Microsoft debuggers require this, and 1582 // will apply the ThisAdjustment in the method type information. 1583 // FIXME: Do something better for DWARF debuggers, which won't expect this, 1584 // without making our codegen depend on debug info settings. 1585 llvm::Value *This = loadIncomingCXXThis(CGF); 1586 const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl()); 1587 if (!CGF.CurFuncIsThunk && MD->isVirtual()) { 1588 CharUnits Adjustment = getVirtualFunctionPrologueThisAdjustment(CGF.CurGD); 1589 if (!Adjustment.isZero()) { 1590 assert(Adjustment.isPositive()); 1591 This = CGF.Builder.CreateConstInBoundsGEP1_32(CGF.Int8Ty, This, 1592 -Adjustment.getQuantity()); 1593 } 1594 } 1595 setCXXABIThisValue(CGF, This); 1596 1597 // If this is a function that the ABI specifies returns 'this', initialize 1598 // the return slot to 'this' at the start of the function. 1599 // 1600 // Unlike the setting of return types, this is done within the ABI 1601 // implementation instead of by clients of CGCXXABI because: 1602 // 1) getThisValue is currently protected 1603 // 2) in theory, an ABI could implement 'this' returns some other way; 1604 // HasThisReturn only specifies a contract, not the implementation 1605 if (HasThisReturn(CGF.CurGD) || hasMostDerivedReturn(CGF.CurGD)) 1606 CGF.Builder.CreateStore(getThisValue(CGF), CGF.ReturnValue); 1607 1608 if (isa<CXXConstructorDecl>(MD) && MD->getParent()->getNumVBases()) { 1609 assert(getStructorImplicitParamDecl(CGF) && 1610 "no implicit parameter for a constructor with virtual bases?"); 1611 getStructorImplicitParamValue(CGF) 1612 = CGF.Builder.CreateLoad( 1613 CGF.GetAddrOfLocalVar(getStructorImplicitParamDecl(CGF)), 1614 "is_most_derived"); 1615 } 1616 1617 if (isDeletingDtor(CGF.CurGD)) { 1618 assert(getStructorImplicitParamDecl(CGF) && 1619 "no implicit parameter for a deleting destructor?"); 1620 getStructorImplicitParamValue(CGF) 1621 = CGF.Builder.CreateLoad( 1622 CGF.GetAddrOfLocalVar(getStructorImplicitParamDecl(CGF)), 1623 "should_call_delete"); 1624 } 1625 } 1626 1627 CGCXXABI::AddedStructorArgs MicrosoftCXXABI::getImplicitConstructorArgs( 1628 CodeGenFunction &CGF, const CXXConstructorDecl *D, CXXCtorType Type, 1629 bool ForVirtualBase, bool Delegating) { 1630 assert(Type == Ctor_Complete || Type == Ctor_Base); 1631 1632 // Check if we need a 'most_derived' parameter. 1633 if (!D->getParent()->getNumVBases()) 1634 return AddedStructorArgs{}; 1635 1636 // Add the 'most_derived' argument second if we are variadic or last if not. 1637 const FunctionProtoType *FPT = D->getType()->castAs<FunctionProtoType>(); 1638 llvm::Value *MostDerivedArg; 1639 if (Delegating) { 1640 MostDerivedArg = getStructorImplicitParamValue(CGF); 1641 } else { 1642 MostDerivedArg = llvm::ConstantInt::get(CGM.Int32Ty, Type == Ctor_Complete); 1643 } 1644 if (FPT->isVariadic()) { 1645 return AddedStructorArgs::prefix({{MostDerivedArg, getContext().IntTy}}); 1646 } 1647 return AddedStructorArgs::suffix({{MostDerivedArg, getContext().IntTy}}); 1648 } 1649 1650 llvm::Value *MicrosoftCXXABI::getCXXDestructorImplicitParam( 1651 CodeGenFunction &CGF, const CXXDestructorDecl *DD, CXXDtorType Type, 1652 bool ForVirtualBase, bool Delegating) { 1653 return nullptr; 1654 } 1655 1656 void MicrosoftCXXABI::EmitDestructorCall(CodeGenFunction &CGF, 1657 const CXXDestructorDecl *DD, 1658 CXXDtorType Type, bool ForVirtualBase, 1659 bool Delegating, Address This, 1660 QualType ThisTy) { 1661 // Use the base destructor variant in place of the complete destructor variant 1662 // if the class has no virtual bases. This effectively implements some of the 1663 // -mconstructor-aliases optimization, but as part of the MS C++ ABI. 1664 if (Type == Dtor_Complete && DD->getParent()->getNumVBases() == 0) 1665 Type = Dtor_Base; 1666 1667 GlobalDecl GD(DD, Type); 1668 CGCallee Callee = CGCallee::forDirect(CGM.getAddrOfCXXStructor(GD), GD); 1669 1670 if (DD->isVirtual()) { 1671 assert(Type != CXXDtorType::Dtor_Deleting && 1672 "The deleting destructor should only be called via a virtual call"); 1673 This = adjustThisArgumentForVirtualFunctionCall(CGF, GlobalDecl(DD, Type), 1674 This, false); 1675 } 1676 1677 llvm::BasicBlock *BaseDtorEndBB = nullptr; 1678 if (ForVirtualBase && isa<CXXConstructorDecl>(CGF.CurCodeDecl)) { 1679 BaseDtorEndBB = EmitDtorCompleteObjectHandler(CGF); 1680 } 1681 1682 llvm::Value *Implicit = 1683 getCXXDestructorImplicitParam(CGF, DD, Type, ForVirtualBase, 1684 Delegating); // = nullptr 1685 CGF.EmitCXXDestructorCall(GD, Callee, CGF.getAsNaturalPointerTo(This, ThisTy), 1686 ThisTy, 1687 /*ImplicitParam=*/Implicit, 1688 /*ImplicitParamTy=*/QualType(), nullptr); 1689 if (BaseDtorEndBB) { 1690 // Complete object handler should continue to be the remaining 1691 CGF.Builder.CreateBr(BaseDtorEndBB); 1692 CGF.EmitBlock(BaseDtorEndBB); 1693 } 1694 } 1695 1696 void MicrosoftCXXABI::emitVTableTypeMetadata(const VPtrInfo &Info, 1697 const CXXRecordDecl *RD, 1698 llvm::GlobalVariable *VTable) { 1699 // Emit type metadata on vtables with LTO or IR instrumentation. 1700 // In IR instrumentation, the type metadata could be used to find out vtable 1701 // definitions (for type profiling) among all global variables. 1702 if (!CGM.getCodeGenOpts().LTOUnit && 1703 !CGM.getCodeGenOpts().hasProfileIRInstr()) 1704 return; 1705 1706 // TODO: Should VirtualFunctionElimination also be supported here? 1707 // See similar handling in CodeGenModule::EmitVTableTypeMetadata. 1708 if (CGM.getCodeGenOpts().WholeProgramVTables) { 1709 llvm::DenseSet<const CXXRecordDecl *> Visited; 1710 llvm::GlobalObject::VCallVisibility TypeVis = 1711 CGM.GetVCallVisibilityLevel(RD, Visited); 1712 if (TypeVis != llvm::GlobalObject::VCallVisibilityPublic) 1713 VTable->setVCallVisibilityMetadata(TypeVis); 1714 } 1715 1716 // The location of the first virtual function pointer in the virtual table, 1717 // aka the "address point" on Itanium. This is at offset 0 if RTTI is 1718 // disabled, or sizeof(void*) if RTTI is enabled. 1719 CharUnits AddressPoint = 1720 getContext().getLangOpts().RTTIData 1721 ? getContext().toCharUnitsFromBits( 1722 getContext().getTargetInfo().getPointerWidth(LangAS::Default)) 1723 : CharUnits::Zero(); 1724 1725 if (Info.PathToIntroducingObject.empty()) { 1726 CGM.AddVTableTypeMetadata(VTable, AddressPoint, RD); 1727 return; 1728 } 1729 1730 // Add a bitset entry for the least derived base belonging to this vftable. 1731 CGM.AddVTableTypeMetadata(VTable, AddressPoint, 1732 Info.PathToIntroducingObject.back()); 1733 1734 // Add a bitset entry for each derived class that is laid out at the same 1735 // offset as the least derived base. 1736 for (unsigned I = Info.PathToIntroducingObject.size() - 1; I != 0; --I) { 1737 const CXXRecordDecl *DerivedRD = Info.PathToIntroducingObject[I - 1]; 1738 const CXXRecordDecl *BaseRD = Info.PathToIntroducingObject[I]; 1739 1740 const ASTRecordLayout &Layout = 1741 getContext().getASTRecordLayout(DerivedRD); 1742 CharUnits Offset; 1743 auto VBI = Layout.getVBaseOffsetsMap().find(BaseRD); 1744 if (VBI == Layout.getVBaseOffsetsMap().end()) 1745 Offset = Layout.getBaseClassOffset(BaseRD); 1746 else 1747 Offset = VBI->second.VBaseOffset; 1748 if (!Offset.isZero()) 1749 return; 1750 CGM.AddVTableTypeMetadata(VTable, AddressPoint, DerivedRD); 1751 } 1752 1753 // Finally do the same for the most derived class. 1754 if (Info.FullOffsetInMDC.isZero()) 1755 CGM.AddVTableTypeMetadata(VTable, AddressPoint, RD); 1756 } 1757 1758 void MicrosoftCXXABI::emitVTableDefinitions(CodeGenVTables &CGVT, 1759 const CXXRecordDecl *RD) { 1760 MicrosoftVTableContext &VFTContext = CGM.getMicrosoftVTableContext(); 1761 const VPtrInfoVector &VFPtrs = VFTContext.getVFPtrOffsets(RD); 1762 1763 for (const std::unique_ptr<VPtrInfo>& Info : VFPtrs) { 1764 llvm::GlobalVariable *VTable = getAddrOfVTable(RD, Info->FullOffsetInMDC); 1765 if (VTable->hasInitializer()) 1766 continue; 1767 1768 const VTableLayout &VTLayout = 1769 VFTContext.getVFTableLayout(RD, Info->FullOffsetInMDC); 1770 1771 llvm::Constant *RTTI = nullptr; 1772 if (any_of(VTLayout.vtable_components(), 1773 [](const VTableComponent &VTC) { return VTC.isRTTIKind(); })) 1774 RTTI = getMSCompleteObjectLocator(RD, *Info); 1775 1776 ConstantInitBuilder builder(CGM); 1777 auto components = builder.beginStruct(); 1778 CGVT.createVTableInitializer(components, VTLayout, RTTI, 1779 VTable->hasLocalLinkage()); 1780 components.finishAndSetAsInitializer(VTable); 1781 1782 emitVTableTypeMetadata(*Info, RD, VTable); 1783 } 1784 } 1785 1786 bool MicrosoftCXXABI::isVirtualOffsetNeededForVTableField( 1787 CodeGenFunction &CGF, CodeGenFunction::VPtr Vptr) { 1788 return Vptr.NearestVBase != nullptr; 1789 } 1790 1791 llvm::Value *MicrosoftCXXABI::getVTableAddressPointInStructor( 1792 CodeGenFunction &CGF, const CXXRecordDecl *VTableClass, BaseSubobject Base, 1793 const CXXRecordDecl *NearestVBase) { 1794 llvm::Constant *VTableAddressPoint = getVTableAddressPoint(Base, VTableClass); 1795 if (!VTableAddressPoint) { 1796 assert(Base.getBase()->getNumVBases() && 1797 !getContext().getASTRecordLayout(Base.getBase()).hasOwnVFPtr()); 1798 } 1799 return VTableAddressPoint; 1800 } 1801 1802 static void mangleVFTableName(MicrosoftMangleContext &MangleContext, 1803 const CXXRecordDecl *RD, const VPtrInfo &VFPtr, 1804 SmallString<256> &Name) { 1805 llvm::raw_svector_ostream Out(Name); 1806 MangleContext.mangleCXXVFTable(RD, VFPtr.MangledPath, Out); 1807 } 1808 1809 llvm::Constant * 1810 MicrosoftCXXABI::getVTableAddressPoint(BaseSubobject Base, 1811 const CXXRecordDecl *VTableClass) { 1812 (void)getAddrOfVTable(VTableClass, Base.getBaseOffset()); 1813 VFTableIdTy ID(VTableClass, Base.getBaseOffset()); 1814 return VFTablesMap[ID]; 1815 } 1816 1817 llvm::GlobalVariable *MicrosoftCXXABI::getAddrOfVTable(const CXXRecordDecl *RD, 1818 CharUnits VPtrOffset) { 1819 // getAddrOfVTable may return 0 if asked to get an address of a vtable which 1820 // shouldn't be used in the given record type. We want to cache this result in 1821 // VFTablesMap, thus a simple zero check is not sufficient. 1822 1823 VFTableIdTy ID(RD, VPtrOffset); 1824 VTablesMapTy::iterator I; 1825 bool Inserted; 1826 std::tie(I, Inserted) = VTablesMap.insert(std::make_pair(ID, nullptr)); 1827 if (!Inserted) 1828 return I->second; 1829 1830 llvm::GlobalVariable *&VTable = I->second; 1831 1832 MicrosoftVTableContext &VTContext = CGM.getMicrosoftVTableContext(); 1833 const VPtrInfoVector &VFPtrs = VTContext.getVFPtrOffsets(RD); 1834 1835 if (DeferredVFTables.insert(RD).second) { 1836 // We haven't processed this record type before. 1837 // Queue up this vtable for possible deferred emission. 1838 CGM.addDeferredVTable(RD); 1839 1840 #ifndef NDEBUG 1841 // Create all the vftables at once in order to make sure each vftable has 1842 // a unique mangled name. 1843 llvm::StringSet<> ObservedMangledNames; 1844 for (size_t J = 0, F = VFPtrs.size(); J != F; ++J) { 1845 SmallString<256> Name; 1846 mangleVFTableName(getMangleContext(), RD, *VFPtrs[J], Name); 1847 if (!ObservedMangledNames.insert(Name.str()).second) 1848 llvm_unreachable("Already saw this mangling before?"); 1849 } 1850 #endif 1851 } 1852 1853 const std::unique_ptr<VPtrInfo> *VFPtrI = 1854 llvm::find_if(VFPtrs, [&](const std::unique_ptr<VPtrInfo> &VPI) { 1855 return VPI->FullOffsetInMDC == VPtrOffset; 1856 }); 1857 if (VFPtrI == VFPtrs.end()) { 1858 VFTablesMap[ID] = nullptr; 1859 return nullptr; 1860 } 1861 const std::unique_ptr<VPtrInfo> &VFPtr = *VFPtrI; 1862 1863 SmallString<256> VFTableName; 1864 mangleVFTableName(getMangleContext(), RD, *VFPtr, VFTableName); 1865 1866 // Classes marked __declspec(dllimport) need vftables generated on the 1867 // import-side in order to support features like constexpr. No other 1868 // translation unit relies on the emission of the local vftable, translation 1869 // units are expected to generate them as needed. 1870 // 1871 // Because of this unique behavior, we maintain this logic here instead of 1872 // getVTableLinkage. 1873 llvm::GlobalValue::LinkageTypes VFTableLinkage = 1874 RD->hasAttr<DLLImportAttr>() ? llvm::GlobalValue::LinkOnceODRLinkage 1875 : CGM.getVTableLinkage(RD); 1876 bool VFTableComesFromAnotherTU = 1877 llvm::GlobalValue::isAvailableExternallyLinkage(VFTableLinkage) || 1878 llvm::GlobalValue::isExternalLinkage(VFTableLinkage); 1879 bool VTableAliasIsRequred = 1880 !VFTableComesFromAnotherTU && getContext().getLangOpts().RTTIData; 1881 1882 if (llvm::GlobalValue *VFTable = 1883 CGM.getModule().getNamedGlobal(VFTableName)) { 1884 VFTablesMap[ID] = VFTable; 1885 VTable = VTableAliasIsRequred 1886 ? cast<llvm::GlobalVariable>( 1887 cast<llvm::GlobalAlias>(VFTable)->getAliaseeObject()) 1888 : cast<llvm::GlobalVariable>(VFTable); 1889 return VTable; 1890 } 1891 1892 const VTableLayout &VTLayout = 1893 VTContext.getVFTableLayout(RD, VFPtr->FullOffsetInMDC); 1894 llvm::GlobalValue::LinkageTypes VTableLinkage = 1895 VTableAliasIsRequred ? llvm::GlobalValue::PrivateLinkage : VFTableLinkage; 1896 1897 StringRef VTableName = VTableAliasIsRequred ? StringRef() : VFTableName.str(); 1898 1899 llvm::Type *VTableType = CGM.getVTables().getVTableType(VTLayout); 1900 1901 // Create a backing variable for the contents of VTable. The VTable may 1902 // or may not include space for a pointer to RTTI data. 1903 llvm::GlobalValue *VFTable; 1904 VTable = new llvm::GlobalVariable(CGM.getModule(), VTableType, 1905 /*isConstant=*/true, VTableLinkage, 1906 /*Initializer=*/nullptr, VTableName); 1907 VTable->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global); 1908 1909 llvm::Comdat *C = nullptr; 1910 if (!VFTableComesFromAnotherTU && 1911 llvm::GlobalValue::isWeakForLinker(VFTableLinkage)) 1912 C = CGM.getModule().getOrInsertComdat(VFTableName.str()); 1913 1914 // Only insert a pointer into the VFTable for RTTI data if we are not 1915 // importing it. We never reference the RTTI data directly so there is no 1916 // need to make room for it. 1917 if (VTableAliasIsRequred) { 1918 llvm::Value *GEPIndices[] = {llvm::ConstantInt::get(CGM.Int32Ty, 0), 1919 llvm::ConstantInt::get(CGM.Int32Ty, 0), 1920 llvm::ConstantInt::get(CGM.Int32Ty, 1)}; 1921 // Create a GEP which points just after the first entry in the VFTable, 1922 // this should be the location of the first virtual method. 1923 llvm::Constant *VTableGEP = llvm::ConstantExpr::getInBoundsGetElementPtr( 1924 VTable->getValueType(), VTable, GEPIndices); 1925 if (llvm::GlobalValue::isWeakForLinker(VFTableLinkage)) { 1926 VFTableLinkage = llvm::GlobalValue::ExternalLinkage; 1927 if (C) 1928 C->setSelectionKind(llvm::Comdat::Largest); 1929 } 1930 VFTable = llvm::GlobalAlias::create(CGM.Int8PtrTy, 1931 /*AddressSpace=*/0, VFTableLinkage, 1932 VFTableName.str(), VTableGEP, 1933 &CGM.getModule()); 1934 VFTable->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global); 1935 } else { 1936 // We don't need a GlobalAlias to be a symbol for the VTable if we won't 1937 // be referencing any RTTI data. 1938 // The GlobalVariable will end up being an appropriate definition of the 1939 // VFTable. 1940 VFTable = VTable; 1941 } 1942 if (C) 1943 VTable->setComdat(C); 1944 1945 if (RD->hasAttr<DLLExportAttr>()) 1946 VFTable->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass); 1947 1948 VFTablesMap[ID] = VFTable; 1949 return VTable; 1950 } 1951 1952 CGCallee MicrosoftCXXABI::getVirtualFunctionPointer(CodeGenFunction &CGF, 1953 GlobalDecl GD, 1954 Address This, 1955 llvm::Type *Ty, 1956 SourceLocation Loc) { 1957 CGBuilderTy &Builder = CGF.Builder; 1958 1959 Ty = Ty->getPointerTo(); 1960 Address VPtr = 1961 adjustThisArgumentForVirtualFunctionCall(CGF, GD, This, true); 1962 1963 auto *MethodDecl = cast<CXXMethodDecl>(GD.getDecl()); 1964 llvm::Value *VTable = CGF.GetVTablePtr(VPtr, Ty->getPointerTo(), 1965 MethodDecl->getParent()); 1966 1967 MicrosoftVTableContext &VFTContext = CGM.getMicrosoftVTableContext(); 1968 MethodVFTableLocation ML = VFTContext.getMethodVFTableLocation(GD); 1969 1970 // Compute the identity of the most derived class whose virtual table is 1971 // located at the MethodVFTableLocation ML. 1972 auto getObjectWithVPtr = [&] { 1973 return llvm::find_if(VFTContext.getVFPtrOffsets( 1974 ML.VBase ? ML.VBase : MethodDecl->getParent()), 1975 [&](const std::unique_ptr<VPtrInfo> &Info) { 1976 return Info->FullOffsetInMDC == ML.VFPtrOffset; 1977 }) 1978 ->get() 1979 ->ObjectWithVPtr; 1980 }; 1981 1982 llvm::Value *VFunc; 1983 if (CGF.ShouldEmitVTableTypeCheckedLoad(MethodDecl->getParent())) { 1984 VFunc = CGF.EmitVTableTypeCheckedLoad( 1985 getObjectWithVPtr(), VTable, Ty, 1986 ML.Index * 1987 CGM.getContext().getTargetInfo().getPointerWidth(LangAS::Default) / 1988 8); 1989 } else { 1990 if (CGM.getCodeGenOpts().PrepareForLTO) 1991 CGF.EmitTypeMetadataCodeForVCall(getObjectWithVPtr(), VTable, Loc); 1992 1993 llvm::Value *VFuncPtr = 1994 Builder.CreateConstInBoundsGEP1_64(Ty, VTable, ML.Index, "vfn"); 1995 VFunc = Builder.CreateAlignedLoad(Ty, VFuncPtr, CGF.getPointerAlign()); 1996 } 1997 1998 CGCallee Callee(GD, VFunc); 1999 return Callee; 2000 } 2001 2002 llvm::Value *MicrosoftCXXABI::EmitVirtualDestructorCall( 2003 CodeGenFunction &CGF, const CXXDestructorDecl *Dtor, CXXDtorType DtorType, 2004 Address This, DeleteOrMemberCallExpr E) { 2005 auto *CE = E.dyn_cast<const CXXMemberCallExpr *>(); 2006 auto *D = E.dyn_cast<const CXXDeleteExpr *>(); 2007 assert((CE != nullptr) ^ (D != nullptr)); 2008 assert(CE == nullptr || CE->arg_begin() == CE->arg_end()); 2009 assert(DtorType == Dtor_Deleting || DtorType == Dtor_Complete); 2010 2011 // We have only one destructor in the vftable but can get both behaviors 2012 // by passing an implicit int parameter. 2013 GlobalDecl GD(Dtor, Dtor_Deleting); 2014 const CGFunctionInfo *FInfo = 2015 &CGM.getTypes().arrangeCXXStructorDeclaration(GD); 2016 llvm::FunctionType *Ty = CGF.CGM.getTypes().GetFunctionType(*FInfo); 2017 CGCallee Callee = CGCallee::forVirtual(CE, GD, This, Ty); 2018 2019 ASTContext &Context = getContext(); 2020 llvm::Value *ImplicitParam = llvm::ConstantInt::get( 2021 llvm::IntegerType::getInt32Ty(CGF.getLLVMContext()), 2022 DtorType == Dtor_Deleting); 2023 2024 QualType ThisTy; 2025 if (CE) { 2026 ThisTy = CE->getObjectType(); 2027 } else { 2028 ThisTy = D->getDestroyedType(); 2029 } 2030 2031 This = adjustThisArgumentForVirtualFunctionCall(CGF, GD, This, true); 2032 RValue RV = 2033 CGF.EmitCXXDestructorCall(GD, Callee, This.emitRawPointer(CGF), ThisTy, 2034 ImplicitParam, Context.IntTy, CE); 2035 return RV.getScalarVal(); 2036 } 2037 2038 const VBTableGlobals & 2039 MicrosoftCXXABI::enumerateVBTables(const CXXRecordDecl *RD) { 2040 // At this layer, we can key the cache off of a single class, which is much 2041 // easier than caching each vbtable individually. 2042 llvm::DenseMap<const CXXRecordDecl*, VBTableGlobals>::iterator Entry; 2043 bool Added; 2044 std::tie(Entry, Added) = 2045 VBTablesMap.insert(std::make_pair(RD, VBTableGlobals())); 2046 VBTableGlobals &VBGlobals = Entry->second; 2047 if (!Added) 2048 return VBGlobals; 2049 2050 MicrosoftVTableContext &Context = CGM.getMicrosoftVTableContext(); 2051 VBGlobals.VBTables = &Context.enumerateVBTables(RD); 2052 2053 // Cache the globals for all vbtables so we don't have to recompute the 2054 // mangled names. 2055 llvm::GlobalVariable::LinkageTypes Linkage = CGM.getVTableLinkage(RD); 2056 for (VPtrInfoVector::const_iterator I = VBGlobals.VBTables->begin(), 2057 E = VBGlobals.VBTables->end(); 2058 I != E; ++I) { 2059 VBGlobals.Globals.push_back(getAddrOfVBTable(**I, RD, Linkage)); 2060 } 2061 2062 return VBGlobals; 2063 } 2064 2065 llvm::Function * 2066 MicrosoftCXXABI::EmitVirtualMemPtrThunk(const CXXMethodDecl *MD, 2067 const MethodVFTableLocation &ML) { 2068 assert(!isa<CXXConstructorDecl>(MD) && !isa<CXXDestructorDecl>(MD) && 2069 "can't form pointers to ctors or virtual dtors"); 2070 2071 // Calculate the mangled name. 2072 SmallString<256> ThunkName; 2073 llvm::raw_svector_ostream Out(ThunkName); 2074 getMangleContext().mangleVirtualMemPtrThunk(MD, ML, Out); 2075 2076 // If the thunk has been generated previously, just return it. 2077 if (llvm::GlobalValue *GV = CGM.getModule().getNamedValue(ThunkName)) 2078 return cast<llvm::Function>(GV); 2079 2080 // Create the llvm::Function. 2081 const CGFunctionInfo &FnInfo = 2082 CGM.getTypes().arrangeUnprototypedMustTailThunk(MD); 2083 llvm::FunctionType *ThunkTy = CGM.getTypes().GetFunctionType(FnInfo); 2084 llvm::Function *ThunkFn = 2085 llvm::Function::Create(ThunkTy, llvm::Function::ExternalLinkage, 2086 ThunkName.str(), &CGM.getModule()); 2087 assert(ThunkFn->getName() == ThunkName && "name was uniqued!"); 2088 2089 ThunkFn->setLinkage(MD->isExternallyVisible() 2090 ? llvm::GlobalValue::LinkOnceODRLinkage 2091 : llvm::GlobalValue::InternalLinkage); 2092 if (MD->isExternallyVisible()) 2093 ThunkFn->setComdat(CGM.getModule().getOrInsertComdat(ThunkFn->getName())); 2094 2095 CGM.SetLLVMFunctionAttributes(MD, FnInfo, ThunkFn, /*IsThunk=*/false); 2096 CGM.SetLLVMFunctionAttributesForDefinition(MD, ThunkFn); 2097 2098 // Add the "thunk" attribute so that LLVM knows that the return type is 2099 // meaningless. These thunks can be used to call functions with differing 2100 // return types, and the caller is required to cast the prototype 2101 // appropriately to extract the correct value. 2102 ThunkFn->addFnAttr("thunk"); 2103 2104 // These thunks can be compared, so they are not unnamed. 2105 ThunkFn->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::None); 2106 2107 // Start codegen. 2108 CodeGenFunction CGF(CGM); 2109 CGF.CurGD = GlobalDecl(MD); 2110 CGF.CurFuncIsThunk = true; 2111 2112 // Build FunctionArgs, but only include the implicit 'this' parameter 2113 // declaration. 2114 FunctionArgList FunctionArgs; 2115 buildThisParam(CGF, FunctionArgs); 2116 2117 // Start defining the function. 2118 CGF.StartFunction(GlobalDecl(), FnInfo.getReturnType(), ThunkFn, FnInfo, 2119 FunctionArgs, MD->getLocation(), SourceLocation()); 2120 2121 ApplyDebugLocation AL(CGF, MD->getLocation()); 2122 setCXXABIThisValue(CGF, loadIncomingCXXThis(CGF)); 2123 2124 // Load the vfptr and then callee from the vftable. The callee should have 2125 // adjusted 'this' so that the vfptr is at offset zero. 2126 llvm::Type *ThunkPtrTy = ThunkTy->getPointerTo(); 2127 llvm::Value *VTable = CGF.GetVTablePtr( 2128 getThisAddress(CGF), ThunkPtrTy->getPointerTo(), MD->getParent()); 2129 2130 llvm::Value *VFuncPtr = CGF.Builder.CreateConstInBoundsGEP1_64( 2131 ThunkPtrTy, VTable, ML.Index, "vfn"); 2132 llvm::Value *Callee = 2133 CGF.Builder.CreateAlignedLoad(ThunkPtrTy, VFuncPtr, CGF.getPointerAlign()); 2134 2135 CGF.EmitMustTailThunk(MD, getThisValue(CGF), {ThunkTy, Callee}); 2136 2137 return ThunkFn; 2138 } 2139 2140 void MicrosoftCXXABI::emitVirtualInheritanceTables(const CXXRecordDecl *RD) { 2141 const VBTableGlobals &VBGlobals = enumerateVBTables(RD); 2142 for (unsigned I = 0, E = VBGlobals.VBTables->size(); I != E; ++I) { 2143 const std::unique_ptr<VPtrInfo>& VBT = (*VBGlobals.VBTables)[I]; 2144 llvm::GlobalVariable *GV = VBGlobals.Globals[I]; 2145 if (GV->isDeclaration()) 2146 emitVBTableDefinition(*VBT, RD, GV); 2147 } 2148 } 2149 2150 llvm::GlobalVariable * 2151 MicrosoftCXXABI::getAddrOfVBTable(const VPtrInfo &VBT, const CXXRecordDecl *RD, 2152 llvm::GlobalVariable::LinkageTypes Linkage) { 2153 SmallString<256> OutName; 2154 llvm::raw_svector_ostream Out(OutName); 2155 getMangleContext().mangleCXXVBTable(RD, VBT.MangledPath, Out); 2156 StringRef Name = OutName.str(); 2157 2158 llvm::ArrayType *VBTableType = 2159 llvm::ArrayType::get(CGM.IntTy, 1 + VBT.ObjectWithVPtr->getNumVBases()); 2160 2161 assert(!CGM.getModule().getNamedGlobal(Name) && 2162 "vbtable with this name already exists: mangling bug?"); 2163 CharUnits Alignment = 2164 CGM.getContext().getTypeAlignInChars(CGM.getContext().IntTy); 2165 llvm::GlobalVariable *GV = CGM.CreateOrReplaceCXXRuntimeVariable( 2166 Name, VBTableType, Linkage, Alignment.getAsAlign()); 2167 GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global); 2168 2169 if (RD->hasAttr<DLLImportAttr>()) 2170 GV->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass); 2171 else if (RD->hasAttr<DLLExportAttr>()) 2172 GV->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass); 2173 2174 if (!GV->hasExternalLinkage()) 2175 emitVBTableDefinition(VBT, RD, GV); 2176 2177 return GV; 2178 } 2179 2180 void MicrosoftCXXABI::emitVBTableDefinition(const VPtrInfo &VBT, 2181 const CXXRecordDecl *RD, 2182 llvm::GlobalVariable *GV) const { 2183 const CXXRecordDecl *ObjectWithVPtr = VBT.ObjectWithVPtr; 2184 2185 assert(RD->getNumVBases() && ObjectWithVPtr->getNumVBases() && 2186 "should only emit vbtables for classes with vbtables"); 2187 2188 const ASTRecordLayout &BaseLayout = 2189 getContext().getASTRecordLayout(VBT.IntroducingObject); 2190 const ASTRecordLayout &DerivedLayout = getContext().getASTRecordLayout(RD); 2191 2192 SmallVector<llvm::Constant *, 4> Offsets(1 + ObjectWithVPtr->getNumVBases(), 2193 nullptr); 2194 2195 // The offset from ObjectWithVPtr's vbptr to itself always leads. 2196 CharUnits VBPtrOffset = BaseLayout.getVBPtrOffset(); 2197 Offsets[0] = llvm::ConstantInt::get(CGM.IntTy, -VBPtrOffset.getQuantity()); 2198 2199 MicrosoftVTableContext &Context = CGM.getMicrosoftVTableContext(); 2200 for (const auto &I : ObjectWithVPtr->vbases()) { 2201 const CXXRecordDecl *VBase = I.getType()->getAsCXXRecordDecl(); 2202 CharUnits Offset = DerivedLayout.getVBaseClassOffset(VBase); 2203 assert(!Offset.isNegative()); 2204 2205 // Make it relative to the subobject vbptr. 2206 CharUnits CompleteVBPtrOffset = VBT.NonVirtualOffset + VBPtrOffset; 2207 if (VBT.getVBaseWithVPtr()) 2208 CompleteVBPtrOffset += 2209 DerivedLayout.getVBaseClassOffset(VBT.getVBaseWithVPtr()); 2210 Offset -= CompleteVBPtrOffset; 2211 2212 unsigned VBIndex = Context.getVBTableIndex(ObjectWithVPtr, VBase); 2213 assert(Offsets[VBIndex] == nullptr && "The same vbindex seen twice?"); 2214 Offsets[VBIndex] = llvm::ConstantInt::get(CGM.IntTy, Offset.getQuantity()); 2215 } 2216 2217 assert(Offsets.size() == 2218 cast<llvm::ArrayType>(GV->getValueType())->getNumElements()); 2219 llvm::ArrayType *VBTableType = 2220 llvm::ArrayType::get(CGM.IntTy, Offsets.size()); 2221 llvm::Constant *Init = llvm::ConstantArray::get(VBTableType, Offsets); 2222 GV->setInitializer(Init); 2223 2224 if (RD->hasAttr<DLLImportAttr>()) 2225 GV->setLinkage(llvm::GlobalVariable::AvailableExternallyLinkage); 2226 } 2227 2228 llvm::Value *MicrosoftCXXABI::performThisAdjustment( 2229 CodeGenFunction &CGF, Address This, 2230 const CXXRecordDecl * /*UnadjustedClass*/, const ThunkInfo &TI) { 2231 const ThisAdjustment &TA = TI.This; 2232 if (TA.isEmpty()) 2233 return This.emitRawPointer(CGF); 2234 2235 This = This.withElementType(CGF.Int8Ty); 2236 2237 llvm::Value *V; 2238 if (TA.Virtual.isEmpty()) { 2239 V = This.emitRawPointer(CGF); 2240 } else { 2241 assert(TA.Virtual.Microsoft.VtordispOffset < 0); 2242 // Adjust the this argument based on the vtordisp value. 2243 Address VtorDispPtr = 2244 CGF.Builder.CreateConstInBoundsByteGEP(This, 2245 CharUnits::fromQuantity(TA.Virtual.Microsoft.VtordispOffset)); 2246 VtorDispPtr = VtorDispPtr.withElementType(CGF.Int32Ty); 2247 llvm::Value *VtorDisp = CGF.Builder.CreateLoad(VtorDispPtr, "vtordisp"); 2248 V = CGF.Builder.CreateGEP(This.getElementType(), This.emitRawPointer(CGF), 2249 CGF.Builder.CreateNeg(VtorDisp)); 2250 2251 // Unfortunately, having applied the vtordisp means that we no 2252 // longer really have a known alignment for the vbptr step. 2253 // We'll assume the vbptr is pointer-aligned. 2254 2255 if (TA.Virtual.Microsoft.VBPtrOffset) { 2256 // If the final overrider is defined in a virtual base other than the one 2257 // that holds the vfptr, we have to use a vtordispex thunk which looks up 2258 // the vbtable of the derived class. 2259 assert(TA.Virtual.Microsoft.VBPtrOffset > 0); 2260 assert(TA.Virtual.Microsoft.VBOffsetOffset >= 0); 2261 llvm::Value *VBPtr; 2262 llvm::Value *VBaseOffset = GetVBaseOffsetFromVBPtr( 2263 CGF, Address(V, CGF.Int8Ty, CGF.getPointerAlign()), 2264 -TA.Virtual.Microsoft.VBPtrOffset, 2265 TA.Virtual.Microsoft.VBOffsetOffset, &VBPtr); 2266 V = CGF.Builder.CreateInBoundsGEP(CGF.Int8Ty, VBPtr, VBaseOffset); 2267 } 2268 } 2269 2270 if (TA.NonVirtual) { 2271 // Non-virtual adjustment might result in a pointer outside the allocated 2272 // object, e.g. if the final overrider class is laid out after the virtual 2273 // base that declares a method in the most derived class. 2274 V = CGF.Builder.CreateConstGEP1_32(CGF.Int8Ty, V, TA.NonVirtual); 2275 } 2276 2277 // Don't need to bitcast back, the call CodeGen will handle this. 2278 return V; 2279 } 2280 2281 llvm::Value *MicrosoftCXXABI::performReturnAdjustment( 2282 CodeGenFunction &CGF, Address Ret, 2283 const CXXRecordDecl * /*UnadjustedClass*/, const ReturnAdjustment &RA) { 2284 2285 if (RA.isEmpty()) 2286 return Ret.emitRawPointer(CGF); 2287 2288 Ret = Ret.withElementType(CGF.Int8Ty); 2289 2290 llvm::Value *V = Ret.emitRawPointer(CGF); 2291 if (RA.Virtual.Microsoft.VBIndex) { 2292 assert(RA.Virtual.Microsoft.VBIndex > 0); 2293 int32_t IntSize = CGF.getIntSize().getQuantity(); 2294 llvm::Value *VBPtr; 2295 llvm::Value *VBaseOffset = 2296 GetVBaseOffsetFromVBPtr(CGF, Ret, RA.Virtual.Microsoft.VBPtrOffset, 2297 IntSize * RA.Virtual.Microsoft.VBIndex, &VBPtr); 2298 V = CGF.Builder.CreateInBoundsGEP(CGF.Int8Ty, VBPtr, VBaseOffset); 2299 } 2300 2301 if (RA.NonVirtual) 2302 V = CGF.Builder.CreateConstInBoundsGEP1_32(CGF.Int8Ty, V, RA.NonVirtual); 2303 2304 return V; 2305 } 2306 2307 bool MicrosoftCXXABI::requiresArrayCookie(const CXXDeleteExpr *expr, 2308 QualType elementType) { 2309 // Microsoft seems to completely ignore the possibility of a 2310 // two-argument usual deallocation function. 2311 return elementType.isDestructedType(); 2312 } 2313 2314 bool MicrosoftCXXABI::requiresArrayCookie(const CXXNewExpr *expr) { 2315 // Microsoft seems to completely ignore the possibility of a 2316 // two-argument usual deallocation function. 2317 return expr->getAllocatedType().isDestructedType(); 2318 } 2319 2320 CharUnits MicrosoftCXXABI::getArrayCookieSizeImpl(QualType type) { 2321 // The array cookie is always a size_t; we then pad that out to the 2322 // alignment of the element type. 2323 ASTContext &Ctx = getContext(); 2324 return std::max(Ctx.getTypeSizeInChars(Ctx.getSizeType()), 2325 Ctx.getTypeAlignInChars(type)); 2326 } 2327 2328 llvm::Value *MicrosoftCXXABI::readArrayCookieImpl(CodeGenFunction &CGF, 2329 Address allocPtr, 2330 CharUnits cookieSize) { 2331 Address numElementsPtr = allocPtr.withElementType(CGF.SizeTy); 2332 return CGF.Builder.CreateLoad(numElementsPtr); 2333 } 2334 2335 Address MicrosoftCXXABI::InitializeArrayCookie(CodeGenFunction &CGF, 2336 Address newPtr, 2337 llvm::Value *numElements, 2338 const CXXNewExpr *expr, 2339 QualType elementType) { 2340 assert(requiresArrayCookie(expr)); 2341 2342 // The size of the cookie. 2343 CharUnits cookieSize = getArrayCookieSizeImpl(elementType); 2344 2345 // Compute an offset to the cookie. 2346 Address cookiePtr = newPtr; 2347 2348 // Write the number of elements into the appropriate slot. 2349 Address numElementsPtr = cookiePtr.withElementType(CGF.SizeTy); 2350 CGF.Builder.CreateStore(numElements, numElementsPtr); 2351 2352 // Finally, compute a pointer to the actual data buffer by skipping 2353 // over the cookie completely. 2354 return CGF.Builder.CreateConstInBoundsByteGEP(newPtr, cookieSize); 2355 } 2356 2357 static void emitGlobalDtorWithTLRegDtor(CodeGenFunction &CGF, const VarDecl &VD, 2358 llvm::FunctionCallee Dtor, 2359 llvm::Constant *Addr) { 2360 // Create a function which calls the destructor. 2361 llvm::Constant *DtorStub = CGF.createAtExitStub(VD, Dtor, Addr); 2362 2363 // extern "C" int __tlregdtor(void (*f)(void)); 2364 llvm::FunctionType *TLRegDtorTy = llvm::FunctionType::get( 2365 CGF.IntTy, DtorStub->getType(), /*isVarArg=*/false); 2366 2367 llvm::FunctionCallee TLRegDtor = CGF.CGM.CreateRuntimeFunction( 2368 TLRegDtorTy, "__tlregdtor", llvm::AttributeList(), /*Local=*/true); 2369 if (llvm::Function *TLRegDtorFn = 2370 dyn_cast<llvm::Function>(TLRegDtor.getCallee())) 2371 TLRegDtorFn->setDoesNotThrow(); 2372 2373 CGF.EmitNounwindRuntimeCall(TLRegDtor, DtorStub); 2374 } 2375 2376 void MicrosoftCXXABI::registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D, 2377 llvm::FunctionCallee Dtor, 2378 llvm::Constant *Addr) { 2379 if (D.isNoDestroy(CGM.getContext())) 2380 return; 2381 2382 if (D.getTLSKind()) 2383 return emitGlobalDtorWithTLRegDtor(CGF, D, Dtor, Addr); 2384 2385 // HLSL doesn't support atexit. 2386 if (CGM.getLangOpts().HLSL) 2387 return CGM.AddCXXDtorEntry(Dtor, Addr); 2388 2389 // The default behavior is to use atexit. 2390 CGF.registerGlobalDtorWithAtExit(D, Dtor, Addr); 2391 } 2392 2393 void MicrosoftCXXABI::EmitThreadLocalInitFuncs( 2394 CodeGenModule &CGM, ArrayRef<const VarDecl *> CXXThreadLocals, 2395 ArrayRef<llvm::Function *> CXXThreadLocalInits, 2396 ArrayRef<const VarDecl *> CXXThreadLocalInitVars) { 2397 if (CXXThreadLocalInits.empty()) 2398 return; 2399 2400 CGM.AppendLinkerOptions(CGM.getTarget().getTriple().getArch() == 2401 llvm::Triple::x86 2402 ? "/include:___dyn_tls_init@12" 2403 : "/include:__dyn_tls_init"); 2404 2405 // This will create a GV in the .CRT$XDU section. It will point to our 2406 // initialization function. The CRT will call all of these function 2407 // pointers at start-up time and, eventually, at thread-creation time. 2408 auto AddToXDU = [&CGM](llvm::Function *InitFunc) { 2409 llvm::GlobalVariable *InitFuncPtr = new llvm::GlobalVariable( 2410 CGM.getModule(), InitFunc->getType(), /*isConstant=*/true, 2411 llvm::GlobalVariable::InternalLinkage, InitFunc, 2412 Twine(InitFunc->getName(), "$initializer$")); 2413 InitFuncPtr->setSection(".CRT$XDU"); 2414 // This variable has discardable linkage, we have to add it to @llvm.used to 2415 // ensure it won't get discarded. 2416 CGM.addUsedGlobal(InitFuncPtr); 2417 return InitFuncPtr; 2418 }; 2419 2420 std::vector<llvm::Function *> NonComdatInits; 2421 for (size_t I = 0, E = CXXThreadLocalInitVars.size(); I != E; ++I) { 2422 llvm::GlobalVariable *GV = cast<llvm::GlobalVariable>( 2423 CGM.GetGlobalValue(CGM.getMangledName(CXXThreadLocalInitVars[I]))); 2424 llvm::Function *F = CXXThreadLocalInits[I]; 2425 2426 // If the GV is already in a comdat group, then we have to join it. 2427 if (llvm::Comdat *C = GV->getComdat()) 2428 AddToXDU(F)->setComdat(C); 2429 else 2430 NonComdatInits.push_back(F); 2431 } 2432 2433 if (!NonComdatInits.empty()) { 2434 llvm::FunctionType *FTy = 2435 llvm::FunctionType::get(CGM.VoidTy, /*isVarArg=*/false); 2436 llvm::Function *InitFunc = CGM.CreateGlobalInitOrCleanUpFunction( 2437 FTy, "__tls_init", CGM.getTypes().arrangeNullaryFunction(), 2438 SourceLocation(), /*TLS=*/true); 2439 CodeGenFunction(CGM).GenerateCXXGlobalInitFunc(InitFunc, NonComdatInits); 2440 2441 AddToXDU(InitFunc); 2442 } 2443 } 2444 2445 static llvm::GlobalValue *getTlsGuardVar(CodeGenModule &CGM) { 2446 // __tls_guard comes from the MSVC runtime and reflects 2447 // whether TLS has been initialized for a particular thread. 2448 // It is set from within __dyn_tls_init by the runtime. 2449 // Every library and executable has its own variable. 2450 llvm::Type *VTy = llvm::Type::getInt8Ty(CGM.getLLVMContext()); 2451 llvm::Constant *TlsGuardConstant = 2452 CGM.CreateRuntimeVariable(VTy, "__tls_guard"); 2453 llvm::GlobalValue *TlsGuard = cast<llvm::GlobalValue>(TlsGuardConstant); 2454 2455 TlsGuard->setThreadLocal(true); 2456 2457 return TlsGuard; 2458 } 2459 2460 static llvm::FunctionCallee getDynTlsOnDemandInitFn(CodeGenModule &CGM) { 2461 // __dyn_tls_on_demand_init comes from the MSVC runtime and triggers 2462 // dynamic TLS initialization by calling __dyn_tls_init internally. 2463 llvm::FunctionType *FTy = 2464 llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()), {}, 2465 /*isVarArg=*/false); 2466 return CGM.CreateRuntimeFunction( 2467 FTy, "__dyn_tls_on_demand_init", 2468 llvm::AttributeList::get(CGM.getLLVMContext(), 2469 llvm::AttributeList::FunctionIndex, 2470 llvm::Attribute::NoUnwind), 2471 /*Local=*/true); 2472 } 2473 2474 static void emitTlsGuardCheck(CodeGenFunction &CGF, llvm::GlobalValue *TlsGuard, 2475 llvm::BasicBlock *DynInitBB, 2476 llvm::BasicBlock *ContinueBB) { 2477 llvm::LoadInst *TlsGuardValue = 2478 CGF.Builder.CreateLoad(Address(TlsGuard, CGF.Int8Ty, CharUnits::One())); 2479 llvm::Value *CmpResult = 2480 CGF.Builder.CreateICmpEQ(TlsGuardValue, CGF.Builder.getInt8(0)); 2481 CGF.Builder.CreateCondBr(CmpResult, DynInitBB, ContinueBB); 2482 } 2483 2484 static void emitDynamicTlsInitializationCall(CodeGenFunction &CGF, 2485 llvm::GlobalValue *TlsGuard, 2486 llvm::BasicBlock *ContinueBB) { 2487 llvm::FunctionCallee Initializer = getDynTlsOnDemandInitFn(CGF.CGM); 2488 llvm::Function *InitializerFunction = 2489 cast<llvm::Function>(Initializer.getCallee()); 2490 llvm::CallInst *CallVal = CGF.Builder.CreateCall(InitializerFunction); 2491 CallVal->setCallingConv(InitializerFunction->getCallingConv()); 2492 2493 CGF.Builder.CreateBr(ContinueBB); 2494 } 2495 2496 static void emitDynamicTlsInitialization(CodeGenFunction &CGF) { 2497 llvm::BasicBlock *DynInitBB = 2498 CGF.createBasicBlock("dyntls.dyn_init", CGF.CurFn); 2499 llvm::BasicBlock *ContinueBB = 2500 CGF.createBasicBlock("dyntls.continue", CGF.CurFn); 2501 2502 llvm::GlobalValue *TlsGuard = getTlsGuardVar(CGF.CGM); 2503 2504 emitTlsGuardCheck(CGF, TlsGuard, DynInitBB, ContinueBB); 2505 CGF.Builder.SetInsertPoint(DynInitBB); 2506 emitDynamicTlsInitializationCall(CGF, TlsGuard, ContinueBB); 2507 CGF.Builder.SetInsertPoint(ContinueBB); 2508 } 2509 2510 LValue MicrosoftCXXABI::EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF, 2511 const VarDecl *VD, 2512 QualType LValType) { 2513 // Dynamic TLS initialization works by checking the state of a 2514 // guard variable (__tls_guard) to see whether TLS initialization 2515 // for a thread has happend yet. 2516 // If not, the initialization is triggered on-demand 2517 // by calling __dyn_tls_on_demand_init. 2518 emitDynamicTlsInitialization(CGF); 2519 2520 // Emit the variable just like any regular global variable. 2521 2522 llvm::Value *V = CGF.CGM.GetAddrOfGlobalVar(VD); 2523 llvm::Type *RealVarTy = CGF.getTypes().ConvertTypeForMem(VD->getType()); 2524 2525 CharUnits Alignment = CGF.getContext().getDeclAlign(VD); 2526 Address Addr(V, RealVarTy, Alignment); 2527 2528 LValue LV = VD->getType()->isReferenceType() 2529 ? CGF.EmitLoadOfReferenceLValue(Addr, VD->getType(), 2530 AlignmentSource::Decl) 2531 : CGF.MakeAddrLValue(Addr, LValType, AlignmentSource::Decl); 2532 return LV; 2533 } 2534 2535 static ConstantAddress getInitThreadEpochPtr(CodeGenModule &CGM) { 2536 StringRef VarName("_Init_thread_epoch"); 2537 CharUnits Align = CGM.getIntAlign(); 2538 if (auto *GV = CGM.getModule().getNamedGlobal(VarName)) 2539 return ConstantAddress(GV, GV->getValueType(), Align); 2540 auto *GV = new llvm::GlobalVariable( 2541 CGM.getModule(), CGM.IntTy, 2542 /*isConstant=*/false, llvm::GlobalVariable::ExternalLinkage, 2543 /*Initializer=*/nullptr, VarName, 2544 /*InsertBefore=*/nullptr, llvm::GlobalVariable::GeneralDynamicTLSModel); 2545 GV->setAlignment(Align.getAsAlign()); 2546 return ConstantAddress(GV, GV->getValueType(), Align); 2547 } 2548 2549 static llvm::FunctionCallee getInitThreadHeaderFn(CodeGenModule &CGM) { 2550 llvm::FunctionType *FTy = 2551 llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()), 2552 CGM.IntTy->getPointerTo(), /*isVarArg=*/false); 2553 return CGM.CreateRuntimeFunction( 2554 FTy, "_Init_thread_header", 2555 llvm::AttributeList::get(CGM.getLLVMContext(), 2556 llvm::AttributeList::FunctionIndex, 2557 llvm::Attribute::NoUnwind), 2558 /*Local=*/true); 2559 } 2560 2561 static llvm::FunctionCallee getInitThreadFooterFn(CodeGenModule &CGM) { 2562 llvm::FunctionType *FTy = 2563 llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()), 2564 CGM.IntTy->getPointerTo(), /*isVarArg=*/false); 2565 return CGM.CreateRuntimeFunction( 2566 FTy, "_Init_thread_footer", 2567 llvm::AttributeList::get(CGM.getLLVMContext(), 2568 llvm::AttributeList::FunctionIndex, 2569 llvm::Attribute::NoUnwind), 2570 /*Local=*/true); 2571 } 2572 2573 static llvm::FunctionCallee getInitThreadAbortFn(CodeGenModule &CGM) { 2574 llvm::FunctionType *FTy = 2575 llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()), 2576 CGM.IntTy->getPointerTo(), /*isVarArg=*/false); 2577 return CGM.CreateRuntimeFunction( 2578 FTy, "_Init_thread_abort", 2579 llvm::AttributeList::get(CGM.getLLVMContext(), 2580 llvm::AttributeList::FunctionIndex, 2581 llvm::Attribute::NoUnwind), 2582 /*Local=*/true); 2583 } 2584 2585 namespace { 2586 struct ResetGuardBit final : EHScopeStack::Cleanup { 2587 Address Guard; 2588 unsigned GuardNum; 2589 ResetGuardBit(Address Guard, unsigned GuardNum) 2590 : Guard(Guard), GuardNum(GuardNum) {} 2591 2592 void Emit(CodeGenFunction &CGF, Flags flags) override { 2593 // Reset the bit in the mask so that the static variable may be 2594 // reinitialized. 2595 CGBuilderTy &Builder = CGF.Builder; 2596 llvm::LoadInst *LI = Builder.CreateLoad(Guard); 2597 llvm::ConstantInt *Mask = 2598 llvm::ConstantInt::get(CGF.IntTy, ~(1ULL << GuardNum)); 2599 Builder.CreateStore(Builder.CreateAnd(LI, Mask), Guard); 2600 } 2601 }; 2602 2603 struct CallInitThreadAbort final : EHScopeStack::Cleanup { 2604 llvm::Value *Guard; 2605 CallInitThreadAbort(RawAddress Guard) : Guard(Guard.getPointer()) {} 2606 2607 void Emit(CodeGenFunction &CGF, Flags flags) override { 2608 // Calling _Init_thread_abort will reset the guard's state. 2609 CGF.EmitNounwindRuntimeCall(getInitThreadAbortFn(CGF.CGM), Guard); 2610 } 2611 }; 2612 } 2613 2614 void MicrosoftCXXABI::EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D, 2615 llvm::GlobalVariable *GV, 2616 bool PerformInit) { 2617 // MSVC only uses guards for static locals. 2618 if (!D.isStaticLocal()) { 2619 assert(GV->hasWeakLinkage() || GV->hasLinkOnceLinkage()); 2620 // GlobalOpt is allowed to discard the initializer, so use linkonce_odr. 2621 llvm::Function *F = CGF.CurFn; 2622 F->setLinkage(llvm::GlobalValue::LinkOnceODRLinkage); 2623 F->setComdat(CGM.getModule().getOrInsertComdat(F->getName())); 2624 CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit); 2625 return; 2626 } 2627 2628 bool ThreadlocalStatic = D.getTLSKind(); 2629 bool ThreadsafeStatic = getContext().getLangOpts().ThreadsafeStatics; 2630 2631 // Thread-safe static variables which aren't thread-specific have a 2632 // per-variable guard. 2633 bool HasPerVariableGuard = ThreadsafeStatic && !ThreadlocalStatic; 2634 2635 CGBuilderTy &Builder = CGF.Builder; 2636 llvm::IntegerType *GuardTy = CGF.Int32Ty; 2637 llvm::ConstantInt *Zero = llvm::ConstantInt::get(GuardTy, 0); 2638 CharUnits GuardAlign = CharUnits::fromQuantity(4); 2639 2640 // Get the guard variable for this function if we have one already. 2641 GuardInfo *GI = nullptr; 2642 if (ThreadlocalStatic) 2643 GI = &ThreadLocalGuardVariableMap[D.getDeclContext()]; 2644 else if (!ThreadsafeStatic) 2645 GI = &GuardVariableMap[D.getDeclContext()]; 2646 2647 llvm::GlobalVariable *GuardVar = GI ? GI->Guard : nullptr; 2648 unsigned GuardNum; 2649 if (D.isExternallyVisible()) { 2650 // Externally visible variables have to be numbered in Sema to properly 2651 // handle unreachable VarDecls. 2652 GuardNum = getContext().getStaticLocalNumber(&D); 2653 assert(GuardNum > 0); 2654 GuardNum--; 2655 } else if (HasPerVariableGuard) { 2656 GuardNum = ThreadSafeGuardNumMap[D.getDeclContext()]++; 2657 } else { 2658 // Non-externally visible variables are numbered here in CodeGen. 2659 GuardNum = GI->BitIndex++; 2660 } 2661 2662 if (!HasPerVariableGuard && GuardNum >= 32) { 2663 if (D.isExternallyVisible()) 2664 ErrorUnsupportedABI(CGF, "more than 32 guarded initializations"); 2665 GuardNum %= 32; 2666 GuardVar = nullptr; 2667 } 2668 2669 if (!GuardVar) { 2670 // Mangle the name for the guard. 2671 SmallString<256> GuardName; 2672 { 2673 llvm::raw_svector_ostream Out(GuardName); 2674 if (HasPerVariableGuard) 2675 getMangleContext().mangleThreadSafeStaticGuardVariable(&D, GuardNum, 2676 Out); 2677 else 2678 getMangleContext().mangleStaticGuardVariable(&D, Out); 2679 } 2680 2681 // Create the guard variable with a zero-initializer. Just absorb linkage, 2682 // visibility and dll storage class from the guarded variable. 2683 GuardVar = 2684 new llvm::GlobalVariable(CGM.getModule(), GuardTy, /*isConstant=*/false, 2685 GV->getLinkage(), Zero, GuardName.str()); 2686 GuardVar->setVisibility(GV->getVisibility()); 2687 GuardVar->setDLLStorageClass(GV->getDLLStorageClass()); 2688 GuardVar->setAlignment(GuardAlign.getAsAlign()); 2689 if (GuardVar->isWeakForLinker()) 2690 GuardVar->setComdat( 2691 CGM.getModule().getOrInsertComdat(GuardVar->getName())); 2692 if (D.getTLSKind()) 2693 CGM.setTLSMode(GuardVar, D); 2694 if (GI && !HasPerVariableGuard) 2695 GI->Guard = GuardVar; 2696 } 2697 2698 ConstantAddress GuardAddr(GuardVar, GuardTy, GuardAlign); 2699 2700 assert(GuardVar->getLinkage() == GV->getLinkage() && 2701 "static local from the same function had different linkage"); 2702 2703 if (!HasPerVariableGuard) { 2704 // Pseudo code for the test: 2705 // if (!(GuardVar & MyGuardBit)) { 2706 // GuardVar |= MyGuardBit; 2707 // ... initialize the object ...; 2708 // } 2709 2710 // Test our bit from the guard variable. 2711 llvm::ConstantInt *Bit = llvm::ConstantInt::get(GuardTy, 1ULL << GuardNum); 2712 llvm::LoadInst *LI = Builder.CreateLoad(GuardAddr); 2713 llvm::Value *NeedsInit = 2714 Builder.CreateICmpEQ(Builder.CreateAnd(LI, Bit), Zero); 2715 llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init"); 2716 llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end"); 2717 CGF.EmitCXXGuardedInitBranch(NeedsInit, InitBlock, EndBlock, 2718 CodeGenFunction::GuardKind::VariableGuard, &D); 2719 2720 // Set our bit in the guard variable and emit the initializer and add a global 2721 // destructor if appropriate. 2722 CGF.EmitBlock(InitBlock); 2723 Builder.CreateStore(Builder.CreateOr(LI, Bit), GuardAddr); 2724 CGF.EHStack.pushCleanup<ResetGuardBit>(EHCleanup, GuardAddr, GuardNum); 2725 CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit); 2726 CGF.PopCleanupBlock(); 2727 Builder.CreateBr(EndBlock); 2728 2729 // Continue. 2730 CGF.EmitBlock(EndBlock); 2731 } else { 2732 // Pseudo code for the test: 2733 // if (TSS > _Init_thread_epoch) { 2734 // _Init_thread_header(&TSS); 2735 // if (TSS == -1) { 2736 // ... initialize the object ...; 2737 // _Init_thread_footer(&TSS); 2738 // } 2739 // } 2740 // 2741 // The algorithm is almost identical to what can be found in the appendix 2742 // found in N2325. 2743 2744 // This BasicBLock determines whether or not we have any work to do. 2745 llvm::LoadInst *FirstGuardLoad = Builder.CreateLoad(GuardAddr); 2746 FirstGuardLoad->setOrdering(llvm::AtomicOrdering::Unordered); 2747 llvm::LoadInst *InitThreadEpoch = 2748 Builder.CreateLoad(getInitThreadEpochPtr(CGM)); 2749 llvm::Value *IsUninitialized = 2750 Builder.CreateICmpSGT(FirstGuardLoad, InitThreadEpoch); 2751 llvm::BasicBlock *AttemptInitBlock = CGF.createBasicBlock("init.attempt"); 2752 llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end"); 2753 CGF.EmitCXXGuardedInitBranch(IsUninitialized, AttemptInitBlock, EndBlock, 2754 CodeGenFunction::GuardKind::VariableGuard, &D); 2755 2756 // This BasicBlock attempts to determine whether or not this thread is 2757 // responsible for doing the initialization. 2758 CGF.EmitBlock(AttemptInitBlock); 2759 CGF.EmitNounwindRuntimeCall(getInitThreadHeaderFn(CGM), 2760 GuardAddr.getPointer()); 2761 llvm::LoadInst *SecondGuardLoad = Builder.CreateLoad(GuardAddr); 2762 SecondGuardLoad->setOrdering(llvm::AtomicOrdering::Unordered); 2763 llvm::Value *ShouldDoInit = 2764 Builder.CreateICmpEQ(SecondGuardLoad, getAllOnesInt()); 2765 llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init"); 2766 Builder.CreateCondBr(ShouldDoInit, InitBlock, EndBlock); 2767 2768 // Ok, we ended up getting selected as the initializing thread. 2769 CGF.EmitBlock(InitBlock); 2770 CGF.EHStack.pushCleanup<CallInitThreadAbort>(EHCleanup, GuardAddr); 2771 CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit); 2772 CGF.PopCleanupBlock(); 2773 CGF.EmitNounwindRuntimeCall(getInitThreadFooterFn(CGM), 2774 GuardAddr.getPointer()); 2775 Builder.CreateBr(EndBlock); 2776 2777 CGF.EmitBlock(EndBlock); 2778 } 2779 } 2780 2781 bool MicrosoftCXXABI::isZeroInitializable(const MemberPointerType *MPT) { 2782 // Null-ness for function memptrs only depends on the first field, which is 2783 // the function pointer. The rest don't matter, so we can zero initialize. 2784 if (MPT->isMemberFunctionPointer()) 2785 return true; 2786 2787 // The virtual base adjustment field is always -1 for null, so if we have one 2788 // we can't zero initialize. The field offset is sometimes also -1 if 0 is a 2789 // valid field offset. 2790 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl(); 2791 MSInheritanceModel Inheritance = RD->getMSInheritanceModel(); 2792 return (!inheritanceModelHasVBTableOffsetField(Inheritance) && 2793 RD->nullFieldOffsetIsZero()); 2794 } 2795 2796 llvm::Type * 2797 MicrosoftCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) { 2798 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl(); 2799 MSInheritanceModel Inheritance = RD->getMSInheritanceModel(); 2800 llvm::SmallVector<llvm::Type *, 4> fields; 2801 if (MPT->isMemberFunctionPointer()) 2802 fields.push_back(CGM.VoidPtrTy); // FunctionPointerOrVirtualThunk 2803 else 2804 fields.push_back(CGM.IntTy); // FieldOffset 2805 2806 if (inheritanceModelHasNVOffsetField(MPT->isMemberFunctionPointer(), 2807 Inheritance)) 2808 fields.push_back(CGM.IntTy); 2809 if (inheritanceModelHasVBPtrOffsetField(Inheritance)) 2810 fields.push_back(CGM.IntTy); 2811 if (inheritanceModelHasVBTableOffsetField(Inheritance)) 2812 fields.push_back(CGM.IntTy); // VirtualBaseAdjustmentOffset 2813 2814 if (fields.size() == 1) 2815 return fields[0]; 2816 return llvm::StructType::get(CGM.getLLVMContext(), fields); 2817 } 2818 2819 void MicrosoftCXXABI:: 2820 GetNullMemberPointerFields(const MemberPointerType *MPT, 2821 llvm::SmallVectorImpl<llvm::Constant *> &fields) { 2822 assert(fields.empty()); 2823 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl(); 2824 MSInheritanceModel Inheritance = RD->getMSInheritanceModel(); 2825 if (MPT->isMemberFunctionPointer()) { 2826 // FunctionPointerOrVirtualThunk 2827 fields.push_back(llvm::Constant::getNullValue(CGM.VoidPtrTy)); 2828 } else { 2829 if (RD->nullFieldOffsetIsZero()) 2830 fields.push_back(getZeroInt()); // FieldOffset 2831 else 2832 fields.push_back(getAllOnesInt()); // FieldOffset 2833 } 2834 2835 if (inheritanceModelHasNVOffsetField(MPT->isMemberFunctionPointer(), 2836 Inheritance)) 2837 fields.push_back(getZeroInt()); 2838 if (inheritanceModelHasVBPtrOffsetField(Inheritance)) 2839 fields.push_back(getZeroInt()); 2840 if (inheritanceModelHasVBTableOffsetField(Inheritance)) 2841 fields.push_back(getAllOnesInt()); 2842 } 2843 2844 llvm::Constant * 2845 MicrosoftCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) { 2846 llvm::SmallVector<llvm::Constant *, 4> fields; 2847 GetNullMemberPointerFields(MPT, fields); 2848 if (fields.size() == 1) 2849 return fields[0]; 2850 llvm::Constant *Res = llvm::ConstantStruct::getAnon(fields); 2851 assert(Res->getType() == ConvertMemberPointerType(MPT)); 2852 return Res; 2853 } 2854 2855 llvm::Constant * 2856 MicrosoftCXXABI::EmitFullMemberPointer(llvm::Constant *FirstField, 2857 bool IsMemberFunction, 2858 const CXXRecordDecl *RD, 2859 CharUnits NonVirtualBaseAdjustment, 2860 unsigned VBTableIndex) { 2861 MSInheritanceModel Inheritance = RD->getMSInheritanceModel(); 2862 2863 // Single inheritance class member pointer are represented as scalars instead 2864 // of aggregates. 2865 if (inheritanceModelHasOnlyOneField(IsMemberFunction, Inheritance)) 2866 return FirstField; 2867 2868 llvm::SmallVector<llvm::Constant *, 4> fields; 2869 fields.push_back(FirstField); 2870 2871 if (inheritanceModelHasNVOffsetField(IsMemberFunction, Inheritance)) 2872 fields.push_back(llvm::ConstantInt::get( 2873 CGM.IntTy, NonVirtualBaseAdjustment.getQuantity())); 2874 2875 if (inheritanceModelHasVBPtrOffsetField(Inheritance)) { 2876 CharUnits Offs = CharUnits::Zero(); 2877 if (VBTableIndex) 2878 Offs = getContext().getASTRecordLayout(RD).getVBPtrOffset(); 2879 fields.push_back(llvm::ConstantInt::get(CGM.IntTy, Offs.getQuantity())); 2880 } 2881 2882 // The rest of the fields are adjusted by conversions to a more derived class. 2883 if (inheritanceModelHasVBTableOffsetField(Inheritance)) 2884 fields.push_back(llvm::ConstantInt::get(CGM.IntTy, VBTableIndex)); 2885 2886 return llvm::ConstantStruct::getAnon(fields); 2887 } 2888 2889 llvm::Constant * 2890 MicrosoftCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT, 2891 CharUnits offset) { 2892 return EmitMemberDataPointer(MPT->getMostRecentCXXRecordDecl(), offset); 2893 } 2894 2895 llvm::Constant *MicrosoftCXXABI::EmitMemberDataPointer(const CXXRecordDecl *RD, 2896 CharUnits offset) { 2897 if (RD->getMSInheritanceModel() == 2898 MSInheritanceModel::Virtual) 2899 offset -= getContext().getOffsetOfBaseWithVBPtr(RD); 2900 llvm::Constant *FirstField = 2901 llvm::ConstantInt::get(CGM.IntTy, offset.getQuantity()); 2902 return EmitFullMemberPointer(FirstField, /*IsMemberFunction=*/false, RD, 2903 CharUnits::Zero(), /*VBTableIndex=*/0); 2904 } 2905 2906 llvm::Constant *MicrosoftCXXABI::EmitMemberPointer(const APValue &MP, 2907 QualType MPType) { 2908 const MemberPointerType *DstTy = MPType->castAs<MemberPointerType>(); 2909 const ValueDecl *MPD = MP.getMemberPointerDecl(); 2910 if (!MPD) 2911 return EmitNullMemberPointer(DstTy); 2912 2913 ASTContext &Ctx = getContext(); 2914 ArrayRef<const CXXRecordDecl *> MemberPointerPath = MP.getMemberPointerPath(); 2915 2916 llvm::Constant *C; 2917 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(MPD)) { 2918 C = EmitMemberFunctionPointer(MD); 2919 } else { 2920 // For a pointer to data member, start off with the offset of the field in 2921 // the class in which it was declared, and convert from there if necessary. 2922 // For indirect field decls, get the outermost anonymous field and use the 2923 // parent class. 2924 CharUnits FieldOffset = Ctx.toCharUnitsFromBits(Ctx.getFieldOffset(MPD)); 2925 const FieldDecl *FD = dyn_cast<FieldDecl>(MPD); 2926 if (!FD) 2927 FD = cast<FieldDecl>(*cast<IndirectFieldDecl>(MPD)->chain_begin()); 2928 const CXXRecordDecl *RD = cast<CXXRecordDecl>(FD->getParent()); 2929 RD = RD->getMostRecentNonInjectedDecl(); 2930 C = EmitMemberDataPointer(RD, FieldOffset); 2931 } 2932 2933 if (!MemberPointerPath.empty()) { 2934 const CXXRecordDecl *SrcRD = cast<CXXRecordDecl>(MPD->getDeclContext()); 2935 const Type *SrcRecTy = Ctx.getTypeDeclType(SrcRD).getTypePtr(); 2936 const MemberPointerType *SrcTy = 2937 Ctx.getMemberPointerType(DstTy->getPointeeType(), SrcRecTy) 2938 ->castAs<MemberPointerType>(); 2939 2940 bool DerivedMember = MP.isMemberPointerToDerivedMember(); 2941 SmallVector<const CXXBaseSpecifier *, 4> DerivedToBasePath; 2942 const CXXRecordDecl *PrevRD = SrcRD; 2943 for (const CXXRecordDecl *PathElem : MemberPointerPath) { 2944 const CXXRecordDecl *Base = nullptr; 2945 const CXXRecordDecl *Derived = nullptr; 2946 if (DerivedMember) { 2947 Base = PathElem; 2948 Derived = PrevRD; 2949 } else { 2950 Base = PrevRD; 2951 Derived = PathElem; 2952 } 2953 for (const CXXBaseSpecifier &BS : Derived->bases()) 2954 if (BS.getType()->getAsCXXRecordDecl()->getCanonicalDecl() == 2955 Base->getCanonicalDecl()) 2956 DerivedToBasePath.push_back(&BS); 2957 PrevRD = PathElem; 2958 } 2959 assert(DerivedToBasePath.size() == MemberPointerPath.size()); 2960 2961 CastKind CK = DerivedMember ? CK_DerivedToBaseMemberPointer 2962 : CK_BaseToDerivedMemberPointer; 2963 C = EmitMemberPointerConversion(SrcTy, DstTy, CK, DerivedToBasePath.begin(), 2964 DerivedToBasePath.end(), C); 2965 } 2966 return C; 2967 } 2968 2969 llvm::Constant * 2970 MicrosoftCXXABI::EmitMemberFunctionPointer(const CXXMethodDecl *MD) { 2971 assert(MD->isInstance() && "Member function must not be static!"); 2972 2973 CharUnits NonVirtualBaseAdjustment = CharUnits::Zero(); 2974 const CXXRecordDecl *RD = MD->getParent()->getMostRecentNonInjectedDecl(); 2975 CodeGenTypes &Types = CGM.getTypes(); 2976 2977 unsigned VBTableIndex = 0; 2978 llvm::Constant *FirstField; 2979 const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>(); 2980 if (!MD->isVirtual()) { 2981 llvm::Type *Ty; 2982 // Check whether the function has a computable LLVM signature. 2983 if (Types.isFuncTypeConvertible(FPT)) { 2984 // The function has a computable LLVM signature; use the correct type. 2985 Ty = Types.GetFunctionType(Types.arrangeCXXMethodDeclaration(MD)); 2986 } else { 2987 // Use an arbitrary non-function type to tell GetAddrOfFunction that the 2988 // function type is incomplete. 2989 Ty = CGM.PtrDiffTy; 2990 } 2991 FirstField = CGM.GetAddrOfFunction(MD, Ty); 2992 } else { 2993 auto &VTableContext = CGM.getMicrosoftVTableContext(); 2994 MethodVFTableLocation ML = VTableContext.getMethodVFTableLocation(MD); 2995 FirstField = EmitVirtualMemPtrThunk(MD, ML); 2996 // Include the vfptr adjustment if the method is in a non-primary vftable. 2997 NonVirtualBaseAdjustment += ML.VFPtrOffset; 2998 if (ML.VBase) 2999 VBTableIndex = VTableContext.getVBTableIndex(RD, ML.VBase) * 4; 3000 } 3001 3002 if (VBTableIndex == 0 && 3003 RD->getMSInheritanceModel() == 3004 MSInheritanceModel::Virtual) 3005 NonVirtualBaseAdjustment -= getContext().getOffsetOfBaseWithVBPtr(RD); 3006 3007 // The rest of the fields are common with data member pointers. 3008 return EmitFullMemberPointer(FirstField, /*IsMemberFunction=*/true, RD, 3009 NonVirtualBaseAdjustment, VBTableIndex); 3010 } 3011 3012 /// Member pointers are the same if they're either bitwise identical *or* both 3013 /// null. Null-ness for function members is determined by the first field, 3014 /// while for data member pointers we must compare all fields. 3015 llvm::Value * 3016 MicrosoftCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF, 3017 llvm::Value *L, 3018 llvm::Value *R, 3019 const MemberPointerType *MPT, 3020 bool Inequality) { 3021 CGBuilderTy &Builder = CGF.Builder; 3022 3023 // Handle != comparisons by switching the sense of all boolean operations. 3024 llvm::ICmpInst::Predicate Eq; 3025 llvm::Instruction::BinaryOps And, Or; 3026 if (Inequality) { 3027 Eq = llvm::ICmpInst::ICMP_NE; 3028 And = llvm::Instruction::Or; 3029 Or = llvm::Instruction::And; 3030 } else { 3031 Eq = llvm::ICmpInst::ICMP_EQ; 3032 And = llvm::Instruction::And; 3033 Or = llvm::Instruction::Or; 3034 } 3035 3036 // If this is a single field member pointer (single inheritance), this is a 3037 // single icmp. 3038 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl(); 3039 MSInheritanceModel Inheritance = RD->getMSInheritanceModel(); 3040 if (inheritanceModelHasOnlyOneField(MPT->isMemberFunctionPointer(), 3041 Inheritance)) 3042 return Builder.CreateICmp(Eq, L, R); 3043 3044 // Compare the first field. 3045 llvm::Value *L0 = Builder.CreateExtractValue(L, 0, "lhs.0"); 3046 llvm::Value *R0 = Builder.CreateExtractValue(R, 0, "rhs.0"); 3047 llvm::Value *Cmp0 = Builder.CreateICmp(Eq, L0, R0, "memptr.cmp.first"); 3048 3049 // Compare everything other than the first field. 3050 llvm::Value *Res = nullptr; 3051 llvm::StructType *LType = cast<llvm::StructType>(L->getType()); 3052 for (unsigned I = 1, E = LType->getNumElements(); I != E; ++I) { 3053 llvm::Value *LF = Builder.CreateExtractValue(L, I); 3054 llvm::Value *RF = Builder.CreateExtractValue(R, I); 3055 llvm::Value *Cmp = Builder.CreateICmp(Eq, LF, RF, "memptr.cmp.rest"); 3056 if (Res) 3057 Res = Builder.CreateBinOp(And, Res, Cmp); 3058 else 3059 Res = Cmp; 3060 } 3061 3062 // Check if the first field is 0 if this is a function pointer. 3063 if (MPT->isMemberFunctionPointer()) { 3064 // (l1 == r1 && ...) || l0 == 0 3065 llvm::Value *Zero = llvm::Constant::getNullValue(L0->getType()); 3066 llvm::Value *IsZero = Builder.CreateICmp(Eq, L0, Zero, "memptr.cmp.iszero"); 3067 Res = Builder.CreateBinOp(Or, Res, IsZero); 3068 } 3069 3070 // Combine the comparison of the first field, which must always be true for 3071 // this comparison to succeeed. 3072 return Builder.CreateBinOp(And, Res, Cmp0, "memptr.cmp"); 3073 } 3074 3075 llvm::Value * 3076 MicrosoftCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF, 3077 llvm::Value *MemPtr, 3078 const MemberPointerType *MPT) { 3079 CGBuilderTy &Builder = CGF.Builder; 3080 llvm::SmallVector<llvm::Constant *, 4> fields; 3081 // We only need one field for member functions. 3082 if (MPT->isMemberFunctionPointer()) 3083 fields.push_back(llvm::Constant::getNullValue(CGM.VoidPtrTy)); 3084 else 3085 GetNullMemberPointerFields(MPT, fields); 3086 assert(!fields.empty()); 3087 llvm::Value *FirstField = MemPtr; 3088 if (MemPtr->getType()->isStructTy()) 3089 FirstField = Builder.CreateExtractValue(MemPtr, 0); 3090 llvm::Value *Res = Builder.CreateICmpNE(FirstField, fields[0], "memptr.cmp0"); 3091 3092 // For function member pointers, we only need to test the function pointer 3093 // field. The other fields if any can be garbage. 3094 if (MPT->isMemberFunctionPointer()) 3095 return Res; 3096 3097 // Otherwise, emit a series of compares and combine the results. 3098 for (int I = 1, E = fields.size(); I < E; ++I) { 3099 llvm::Value *Field = Builder.CreateExtractValue(MemPtr, I); 3100 llvm::Value *Next = Builder.CreateICmpNE(Field, fields[I], "memptr.cmp"); 3101 Res = Builder.CreateOr(Res, Next, "memptr.tobool"); 3102 } 3103 return Res; 3104 } 3105 3106 bool MicrosoftCXXABI::MemberPointerConstantIsNull(const MemberPointerType *MPT, 3107 llvm::Constant *Val) { 3108 // Function pointers are null if the pointer in the first field is null. 3109 if (MPT->isMemberFunctionPointer()) { 3110 llvm::Constant *FirstField = Val->getType()->isStructTy() ? 3111 Val->getAggregateElement(0U) : Val; 3112 return FirstField->isNullValue(); 3113 } 3114 3115 // If it's not a function pointer and it's zero initializable, we can easily 3116 // check zero. 3117 if (isZeroInitializable(MPT) && Val->isNullValue()) 3118 return true; 3119 3120 // Otherwise, break down all the fields for comparison. Hopefully these 3121 // little Constants are reused, while a big null struct might not be. 3122 llvm::SmallVector<llvm::Constant *, 4> Fields; 3123 GetNullMemberPointerFields(MPT, Fields); 3124 if (Fields.size() == 1) { 3125 assert(Val->getType()->isIntegerTy()); 3126 return Val == Fields[0]; 3127 } 3128 3129 unsigned I, E; 3130 for (I = 0, E = Fields.size(); I != E; ++I) { 3131 if (Val->getAggregateElement(I) != Fields[I]) 3132 break; 3133 } 3134 return I == E; 3135 } 3136 3137 llvm::Value * 3138 MicrosoftCXXABI::GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF, 3139 Address This, 3140 llvm::Value *VBPtrOffset, 3141 llvm::Value *VBTableOffset, 3142 llvm::Value **VBPtrOut) { 3143 CGBuilderTy &Builder = CGF.Builder; 3144 // Load the vbtable pointer from the vbptr in the instance. 3145 llvm::Value *VBPtr = Builder.CreateInBoundsGEP( 3146 CGM.Int8Ty, This.emitRawPointer(CGF), VBPtrOffset, "vbptr"); 3147 if (VBPtrOut) 3148 *VBPtrOut = VBPtr; 3149 3150 CharUnits VBPtrAlign; 3151 if (auto CI = dyn_cast<llvm::ConstantInt>(VBPtrOffset)) { 3152 VBPtrAlign = This.getAlignment().alignmentAtOffset( 3153 CharUnits::fromQuantity(CI->getSExtValue())); 3154 } else { 3155 VBPtrAlign = CGF.getPointerAlign(); 3156 } 3157 3158 llvm::Value *VBTable = Builder.CreateAlignedLoad( 3159 CGM.Int32Ty->getPointerTo(0), VBPtr, VBPtrAlign, "vbtable"); 3160 3161 // Translate from byte offset to table index. It improves analyzability. 3162 llvm::Value *VBTableIndex = Builder.CreateAShr( 3163 VBTableOffset, llvm::ConstantInt::get(VBTableOffset->getType(), 2), 3164 "vbtindex", /*isExact=*/true); 3165 3166 // Load an i32 offset from the vb-table. 3167 llvm::Value *VBaseOffs = 3168 Builder.CreateInBoundsGEP(CGM.Int32Ty, VBTable, VBTableIndex); 3169 return Builder.CreateAlignedLoad(CGM.Int32Ty, VBaseOffs, 3170 CharUnits::fromQuantity(4), "vbase_offs"); 3171 } 3172 3173 // Returns an adjusted base cast to i8*, since we do more address arithmetic on 3174 // it. 3175 llvm::Value *MicrosoftCXXABI::AdjustVirtualBase( 3176 CodeGenFunction &CGF, const Expr *E, const CXXRecordDecl *RD, 3177 Address Base, llvm::Value *VBTableOffset, llvm::Value *VBPtrOffset) { 3178 CGBuilderTy &Builder = CGF.Builder; 3179 Base = Base.withElementType(CGM.Int8Ty); 3180 llvm::BasicBlock *OriginalBB = nullptr; 3181 llvm::BasicBlock *SkipAdjustBB = nullptr; 3182 llvm::BasicBlock *VBaseAdjustBB = nullptr; 3183 3184 // In the unspecified inheritance model, there might not be a vbtable at all, 3185 // in which case we need to skip the virtual base lookup. If there is a 3186 // vbtable, the first entry is a no-op entry that gives back the original 3187 // base, so look for a virtual base adjustment offset of zero. 3188 if (VBPtrOffset) { 3189 OriginalBB = Builder.GetInsertBlock(); 3190 VBaseAdjustBB = CGF.createBasicBlock("memptr.vadjust"); 3191 SkipAdjustBB = CGF.createBasicBlock("memptr.skip_vadjust"); 3192 llvm::Value *IsVirtual = 3193 Builder.CreateICmpNE(VBTableOffset, getZeroInt(), 3194 "memptr.is_vbase"); 3195 Builder.CreateCondBr(IsVirtual, VBaseAdjustBB, SkipAdjustBB); 3196 CGF.EmitBlock(VBaseAdjustBB); 3197 } 3198 3199 // If we weren't given a dynamic vbptr offset, RD should be complete and we'll 3200 // know the vbptr offset. 3201 if (!VBPtrOffset) { 3202 CharUnits offs = CharUnits::Zero(); 3203 if (!RD->hasDefinition()) { 3204 DiagnosticsEngine &Diags = CGF.CGM.getDiags(); 3205 unsigned DiagID = Diags.getCustomDiagID( 3206 DiagnosticsEngine::Error, 3207 "member pointer representation requires a " 3208 "complete class type for %0 to perform this expression"); 3209 Diags.Report(E->getExprLoc(), DiagID) << RD << E->getSourceRange(); 3210 } else if (RD->getNumVBases()) 3211 offs = getContext().getASTRecordLayout(RD).getVBPtrOffset(); 3212 VBPtrOffset = llvm::ConstantInt::get(CGM.IntTy, offs.getQuantity()); 3213 } 3214 llvm::Value *VBPtr = nullptr; 3215 llvm::Value *VBaseOffs = 3216 GetVBaseOffsetFromVBPtr(CGF, Base, VBPtrOffset, VBTableOffset, &VBPtr); 3217 llvm::Value *AdjustedBase = 3218 Builder.CreateInBoundsGEP(CGM.Int8Ty, VBPtr, VBaseOffs); 3219 3220 // Merge control flow with the case where we didn't have to adjust. 3221 if (VBaseAdjustBB) { 3222 Builder.CreateBr(SkipAdjustBB); 3223 CGF.EmitBlock(SkipAdjustBB); 3224 llvm::PHINode *Phi = Builder.CreatePHI(CGM.Int8PtrTy, 2, "memptr.base"); 3225 Phi->addIncoming(Base.emitRawPointer(CGF), OriginalBB); 3226 Phi->addIncoming(AdjustedBase, VBaseAdjustBB); 3227 return Phi; 3228 } 3229 return AdjustedBase; 3230 } 3231 3232 llvm::Value *MicrosoftCXXABI::EmitMemberDataPointerAddress( 3233 CodeGenFunction &CGF, const Expr *E, Address Base, llvm::Value *MemPtr, 3234 const MemberPointerType *MPT) { 3235 assert(MPT->isMemberDataPointer()); 3236 CGBuilderTy &Builder = CGF.Builder; 3237 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl(); 3238 MSInheritanceModel Inheritance = RD->getMSInheritanceModel(); 3239 3240 // Extract the fields we need, regardless of model. We'll apply them if we 3241 // have them. 3242 llvm::Value *FieldOffset = MemPtr; 3243 llvm::Value *VirtualBaseAdjustmentOffset = nullptr; 3244 llvm::Value *VBPtrOffset = nullptr; 3245 if (MemPtr->getType()->isStructTy()) { 3246 // We need to extract values. 3247 unsigned I = 0; 3248 FieldOffset = Builder.CreateExtractValue(MemPtr, I++); 3249 if (inheritanceModelHasVBPtrOffsetField(Inheritance)) 3250 VBPtrOffset = Builder.CreateExtractValue(MemPtr, I++); 3251 if (inheritanceModelHasVBTableOffsetField(Inheritance)) 3252 VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(MemPtr, I++); 3253 } 3254 3255 llvm::Value *Addr; 3256 if (VirtualBaseAdjustmentOffset) { 3257 Addr = AdjustVirtualBase(CGF, E, RD, Base, VirtualBaseAdjustmentOffset, 3258 VBPtrOffset); 3259 } else { 3260 Addr = Base.emitRawPointer(CGF); 3261 } 3262 3263 // Apply the offset, which we assume is non-null. 3264 return Builder.CreateInBoundsGEP(CGF.Int8Ty, Addr, FieldOffset, 3265 "memptr.offset"); 3266 } 3267 3268 llvm::Value * 3269 MicrosoftCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF, 3270 const CastExpr *E, 3271 llvm::Value *Src) { 3272 assert(E->getCastKind() == CK_DerivedToBaseMemberPointer || 3273 E->getCastKind() == CK_BaseToDerivedMemberPointer || 3274 E->getCastKind() == CK_ReinterpretMemberPointer); 3275 3276 // Use constant emission if we can. 3277 if (isa<llvm::Constant>(Src)) 3278 return EmitMemberPointerConversion(E, cast<llvm::Constant>(Src)); 3279 3280 // We may be adding or dropping fields from the member pointer, so we need 3281 // both types and the inheritance models of both records. 3282 const MemberPointerType *SrcTy = 3283 E->getSubExpr()->getType()->castAs<MemberPointerType>(); 3284 const MemberPointerType *DstTy = E->getType()->castAs<MemberPointerType>(); 3285 bool IsFunc = SrcTy->isMemberFunctionPointer(); 3286 3287 // If the classes use the same null representation, reinterpret_cast is a nop. 3288 bool IsReinterpret = E->getCastKind() == CK_ReinterpretMemberPointer; 3289 if (IsReinterpret && IsFunc) 3290 return Src; 3291 3292 CXXRecordDecl *SrcRD = SrcTy->getMostRecentCXXRecordDecl(); 3293 CXXRecordDecl *DstRD = DstTy->getMostRecentCXXRecordDecl(); 3294 if (IsReinterpret && 3295 SrcRD->nullFieldOffsetIsZero() == DstRD->nullFieldOffsetIsZero()) 3296 return Src; 3297 3298 CGBuilderTy &Builder = CGF.Builder; 3299 3300 // Branch past the conversion if Src is null. 3301 llvm::Value *IsNotNull = EmitMemberPointerIsNotNull(CGF, Src, SrcTy); 3302 llvm::Constant *DstNull = EmitNullMemberPointer(DstTy); 3303 3304 // C++ 5.2.10p9: The null member pointer value is converted to the null member 3305 // pointer value of the destination type. 3306 if (IsReinterpret) { 3307 // For reinterpret casts, sema ensures that src and dst are both functions 3308 // or data and have the same size, which means the LLVM types should match. 3309 assert(Src->getType() == DstNull->getType()); 3310 return Builder.CreateSelect(IsNotNull, Src, DstNull); 3311 } 3312 3313 llvm::BasicBlock *OriginalBB = Builder.GetInsertBlock(); 3314 llvm::BasicBlock *ConvertBB = CGF.createBasicBlock("memptr.convert"); 3315 llvm::BasicBlock *ContinueBB = CGF.createBasicBlock("memptr.converted"); 3316 Builder.CreateCondBr(IsNotNull, ConvertBB, ContinueBB); 3317 CGF.EmitBlock(ConvertBB); 3318 3319 llvm::Value *Dst = EmitNonNullMemberPointerConversion( 3320 SrcTy, DstTy, E->getCastKind(), E->path_begin(), E->path_end(), Src, 3321 Builder); 3322 3323 Builder.CreateBr(ContinueBB); 3324 3325 // In the continuation, choose between DstNull and Dst. 3326 CGF.EmitBlock(ContinueBB); 3327 llvm::PHINode *Phi = Builder.CreatePHI(DstNull->getType(), 2, "memptr.converted"); 3328 Phi->addIncoming(DstNull, OriginalBB); 3329 Phi->addIncoming(Dst, ConvertBB); 3330 return Phi; 3331 } 3332 3333 llvm::Value *MicrosoftCXXABI::EmitNonNullMemberPointerConversion( 3334 const MemberPointerType *SrcTy, const MemberPointerType *DstTy, CastKind CK, 3335 CastExpr::path_const_iterator PathBegin, 3336 CastExpr::path_const_iterator PathEnd, llvm::Value *Src, 3337 CGBuilderTy &Builder) { 3338 const CXXRecordDecl *SrcRD = SrcTy->getMostRecentCXXRecordDecl(); 3339 const CXXRecordDecl *DstRD = DstTy->getMostRecentCXXRecordDecl(); 3340 MSInheritanceModel SrcInheritance = SrcRD->getMSInheritanceModel(); 3341 MSInheritanceModel DstInheritance = DstRD->getMSInheritanceModel(); 3342 bool IsFunc = SrcTy->isMemberFunctionPointer(); 3343 bool IsConstant = isa<llvm::Constant>(Src); 3344 3345 // Decompose src. 3346 llvm::Value *FirstField = Src; 3347 llvm::Value *NonVirtualBaseAdjustment = getZeroInt(); 3348 llvm::Value *VirtualBaseAdjustmentOffset = getZeroInt(); 3349 llvm::Value *VBPtrOffset = getZeroInt(); 3350 if (!inheritanceModelHasOnlyOneField(IsFunc, SrcInheritance)) { 3351 // We need to extract values. 3352 unsigned I = 0; 3353 FirstField = Builder.CreateExtractValue(Src, I++); 3354 if (inheritanceModelHasNVOffsetField(IsFunc, SrcInheritance)) 3355 NonVirtualBaseAdjustment = Builder.CreateExtractValue(Src, I++); 3356 if (inheritanceModelHasVBPtrOffsetField(SrcInheritance)) 3357 VBPtrOffset = Builder.CreateExtractValue(Src, I++); 3358 if (inheritanceModelHasVBTableOffsetField(SrcInheritance)) 3359 VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(Src, I++); 3360 } 3361 3362 bool IsDerivedToBase = (CK == CK_DerivedToBaseMemberPointer); 3363 const MemberPointerType *DerivedTy = IsDerivedToBase ? SrcTy : DstTy; 3364 const CXXRecordDecl *DerivedClass = DerivedTy->getMostRecentCXXRecordDecl(); 3365 3366 // For data pointers, we adjust the field offset directly. For functions, we 3367 // have a separate field. 3368 llvm::Value *&NVAdjustField = IsFunc ? NonVirtualBaseAdjustment : FirstField; 3369 3370 // The virtual inheritance model has a quirk: the virtual base table is always 3371 // referenced when dereferencing a member pointer even if the member pointer 3372 // is non-virtual. This is accounted for by adjusting the non-virtual offset 3373 // to point backwards to the top of the MDC from the first VBase. Undo this 3374 // adjustment to normalize the member pointer. 3375 llvm::Value *SrcVBIndexEqZero = 3376 Builder.CreateICmpEQ(VirtualBaseAdjustmentOffset, getZeroInt()); 3377 if (SrcInheritance == MSInheritanceModel::Virtual) { 3378 if (int64_t SrcOffsetToFirstVBase = 3379 getContext().getOffsetOfBaseWithVBPtr(SrcRD).getQuantity()) { 3380 llvm::Value *UndoSrcAdjustment = Builder.CreateSelect( 3381 SrcVBIndexEqZero, 3382 llvm::ConstantInt::get(CGM.IntTy, SrcOffsetToFirstVBase), 3383 getZeroInt()); 3384 NVAdjustField = Builder.CreateNSWAdd(NVAdjustField, UndoSrcAdjustment); 3385 } 3386 } 3387 3388 // A non-zero vbindex implies that we are dealing with a source member in a 3389 // floating virtual base in addition to some non-virtual offset. If the 3390 // vbindex is zero, we are dealing with a source that exists in a non-virtual, 3391 // fixed, base. The difference between these two cases is that the vbindex + 3392 // nvoffset *always* point to the member regardless of what context they are 3393 // evaluated in so long as the vbindex is adjusted. A member inside a fixed 3394 // base requires explicit nv adjustment. 3395 llvm::Constant *BaseClassOffset = llvm::ConstantInt::get( 3396 CGM.IntTy, 3397 CGM.computeNonVirtualBaseClassOffset(DerivedClass, PathBegin, PathEnd) 3398 .getQuantity()); 3399 3400 llvm::Value *NVDisp; 3401 if (IsDerivedToBase) 3402 NVDisp = Builder.CreateNSWSub(NVAdjustField, BaseClassOffset, "adj"); 3403 else 3404 NVDisp = Builder.CreateNSWAdd(NVAdjustField, BaseClassOffset, "adj"); 3405 3406 NVAdjustField = Builder.CreateSelect(SrcVBIndexEqZero, NVDisp, getZeroInt()); 3407 3408 // Update the vbindex to an appropriate value in the destination because 3409 // SrcRD's vbtable might not be a strict prefix of the one in DstRD. 3410 llvm::Value *DstVBIndexEqZero = SrcVBIndexEqZero; 3411 if (inheritanceModelHasVBTableOffsetField(DstInheritance) && 3412 inheritanceModelHasVBTableOffsetField(SrcInheritance)) { 3413 if (llvm::GlobalVariable *VDispMap = 3414 getAddrOfVirtualDisplacementMap(SrcRD, DstRD)) { 3415 llvm::Value *VBIndex = Builder.CreateExactUDiv( 3416 VirtualBaseAdjustmentOffset, llvm::ConstantInt::get(CGM.IntTy, 4)); 3417 if (IsConstant) { 3418 llvm::Constant *Mapping = VDispMap->getInitializer(); 3419 VirtualBaseAdjustmentOffset = 3420 Mapping->getAggregateElement(cast<llvm::Constant>(VBIndex)); 3421 } else { 3422 llvm::Value *Idxs[] = {getZeroInt(), VBIndex}; 3423 VirtualBaseAdjustmentOffset = Builder.CreateAlignedLoad( 3424 CGM.IntTy, Builder.CreateInBoundsGEP(VDispMap->getValueType(), 3425 VDispMap, Idxs), 3426 CharUnits::fromQuantity(4)); 3427 } 3428 3429 DstVBIndexEqZero = 3430 Builder.CreateICmpEQ(VirtualBaseAdjustmentOffset, getZeroInt()); 3431 } 3432 } 3433 3434 // Set the VBPtrOffset to zero if the vbindex is zero. Otherwise, initialize 3435 // it to the offset of the vbptr. 3436 if (inheritanceModelHasVBPtrOffsetField(DstInheritance)) { 3437 llvm::Value *DstVBPtrOffset = llvm::ConstantInt::get( 3438 CGM.IntTy, 3439 getContext().getASTRecordLayout(DstRD).getVBPtrOffset().getQuantity()); 3440 VBPtrOffset = 3441 Builder.CreateSelect(DstVBIndexEqZero, getZeroInt(), DstVBPtrOffset); 3442 } 3443 3444 // Likewise, apply a similar adjustment so that dereferencing the member 3445 // pointer correctly accounts for the distance between the start of the first 3446 // virtual base and the top of the MDC. 3447 if (DstInheritance == MSInheritanceModel::Virtual) { 3448 if (int64_t DstOffsetToFirstVBase = 3449 getContext().getOffsetOfBaseWithVBPtr(DstRD).getQuantity()) { 3450 llvm::Value *DoDstAdjustment = Builder.CreateSelect( 3451 DstVBIndexEqZero, 3452 llvm::ConstantInt::get(CGM.IntTy, DstOffsetToFirstVBase), 3453 getZeroInt()); 3454 NVAdjustField = Builder.CreateNSWSub(NVAdjustField, DoDstAdjustment); 3455 } 3456 } 3457 3458 // Recompose dst from the null struct and the adjusted fields from src. 3459 llvm::Value *Dst; 3460 if (inheritanceModelHasOnlyOneField(IsFunc, DstInheritance)) { 3461 Dst = FirstField; 3462 } else { 3463 Dst = llvm::UndefValue::get(ConvertMemberPointerType(DstTy)); 3464 unsigned Idx = 0; 3465 Dst = Builder.CreateInsertValue(Dst, FirstField, Idx++); 3466 if (inheritanceModelHasNVOffsetField(IsFunc, DstInheritance)) 3467 Dst = Builder.CreateInsertValue(Dst, NonVirtualBaseAdjustment, Idx++); 3468 if (inheritanceModelHasVBPtrOffsetField(DstInheritance)) 3469 Dst = Builder.CreateInsertValue(Dst, VBPtrOffset, Idx++); 3470 if (inheritanceModelHasVBTableOffsetField(DstInheritance)) 3471 Dst = Builder.CreateInsertValue(Dst, VirtualBaseAdjustmentOffset, Idx++); 3472 } 3473 return Dst; 3474 } 3475 3476 llvm::Constant * 3477 MicrosoftCXXABI::EmitMemberPointerConversion(const CastExpr *E, 3478 llvm::Constant *Src) { 3479 const MemberPointerType *SrcTy = 3480 E->getSubExpr()->getType()->castAs<MemberPointerType>(); 3481 const MemberPointerType *DstTy = E->getType()->castAs<MemberPointerType>(); 3482 3483 CastKind CK = E->getCastKind(); 3484 3485 return EmitMemberPointerConversion(SrcTy, DstTy, CK, E->path_begin(), 3486 E->path_end(), Src); 3487 } 3488 3489 llvm::Constant *MicrosoftCXXABI::EmitMemberPointerConversion( 3490 const MemberPointerType *SrcTy, const MemberPointerType *DstTy, CastKind CK, 3491 CastExpr::path_const_iterator PathBegin, 3492 CastExpr::path_const_iterator PathEnd, llvm::Constant *Src) { 3493 assert(CK == CK_DerivedToBaseMemberPointer || 3494 CK == CK_BaseToDerivedMemberPointer || 3495 CK == CK_ReinterpretMemberPointer); 3496 // If src is null, emit a new null for dst. We can't return src because dst 3497 // might have a new representation. 3498 if (MemberPointerConstantIsNull(SrcTy, Src)) 3499 return EmitNullMemberPointer(DstTy); 3500 3501 // We don't need to do anything for reinterpret_casts of non-null member 3502 // pointers. We should only get here when the two type representations have 3503 // the same size. 3504 if (CK == CK_ReinterpretMemberPointer) 3505 return Src; 3506 3507 CGBuilderTy Builder(CGM, CGM.getLLVMContext()); 3508 auto *Dst = cast<llvm::Constant>(EmitNonNullMemberPointerConversion( 3509 SrcTy, DstTy, CK, PathBegin, PathEnd, Src, Builder)); 3510 3511 return Dst; 3512 } 3513 3514 CGCallee MicrosoftCXXABI::EmitLoadOfMemberFunctionPointer( 3515 CodeGenFunction &CGF, const Expr *E, Address This, 3516 llvm::Value *&ThisPtrForCall, llvm::Value *MemPtr, 3517 const MemberPointerType *MPT) { 3518 assert(MPT->isMemberFunctionPointer()); 3519 const FunctionProtoType *FPT = 3520 MPT->getPointeeType()->castAs<FunctionProtoType>(); 3521 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl(); 3522 CGBuilderTy &Builder = CGF.Builder; 3523 3524 MSInheritanceModel Inheritance = RD->getMSInheritanceModel(); 3525 3526 // Extract the fields we need, regardless of model. We'll apply them if we 3527 // have them. 3528 llvm::Value *FunctionPointer = MemPtr; 3529 llvm::Value *NonVirtualBaseAdjustment = nullptr; 3530 llvm::Value *VirtualBaseAdjustmentOffset = nullptr; 3531 llvm::Value *VBPtrOffset = nullptr; 3532 if (MemPtr->getType()->isStructTy()) { 3533 // We need to extract values. 3534 unsigned I = 0; 3535 FunctionPointer = Builder.CreateExtractValue(MemPtr, I++); 3536 if (inheritanceModelHasNVOffsetField(MPT, Inheritance)) 3537 NonVirtualBaseAdjustment = Builder.CreateExtractValue(MemPtr, I++); 3538 if (inheritanceModelHasVBPtrOffsetField(Inheritance)) 3539 VBPtrOffset = Builder.CreateExtractValue(MemPtr, I++); 3540 if (inheritanceModelHasVBTableOffsetField(Inheritance)) 3541 VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(MemPtr, I++); 3542 } 3543 3544 if (VirtualBaseAdjustmentOffset) { 3545 ThisPtrForCall = AdjustVirtualBase(CGF, E, RD, This, 3546 VirtualBaseAdjustmentOffset, VBPtrOffset); 3547 } else { 3548 ThisPtrForCall = This.emitRawPointer(CGF); 3549 } 3550 3551 if (NonVirtualBaseAdjustment) 3552 ThisPtrForCall = Builder.CreateInBoundsGEP(CGF.Int8Ty, ThisPtrForCall, 3553 NonVirtualBaseAdjustment); 3554 3555 CGCallee Callee(FPT, FunctionPointer); 3556 return Callee; 3557 } 3558 3559 CGCXXABI *clang::CodeGen::CreateMicrosoftCXXABI(CodeGenModule &CGM) { 3560 return new MicrosoftCXXABI(CGM); 3561 } 3562 3563 // MS RTTI Overview: 3564 // The run time type information emitted by cl.exe contains 5 distinct types of 3565 // structures. Many of them reference each other. 3566 // 3567 // TypeInfo: Static classes that are returned by typeid. 3568 // 3569 // CompleteObjectLocator: Referenced by vftables. They contain information 3570 // required for dynamic casting, including OffsetFromTop. They also contain 3571 // a reference to the TypeInfo for the type and a reference to the 3572 // CompleteHierarchyDescriptor for the type. 3573 // 3574 // ClassHierarchyDescriptor: Contains information about a class hierarchy. 3575 // Used during dynamic_cast to walk a class hierarchy. References a base 3576 // class array and the size of said array. 3577 // 3578 // BaseClassArray: Contains a list of classes in a hierarchy. BaseClassArray is 3579 // somewhat of a misnomer because the most derived class is also in the list 3580 // as well as multiple copies of virtual bases (if they occur multiple times 3581 // in the hierarchy.) The BaseClassArray contains one BaseClassDescriptor for 3582 // every path in the hierarchy, in pre-order depth first order. Note, we do 3583 // not declare a specific llvm type for BaseClassArray, it's merely an array 3584 // of BaseClassDescriptor pointers. 3585 // 3586 // BaseClassDescriptor: Contains information about a class in a class hierarchy. 3587 // BaseClassDescriptor is also somewhat of a misnomer for the same reason that 3588 // BaseClassArray is. It contains information about a class within a 3589 // hierarchy such as: is this base is ambiguous and what is its offset in the 3590 // vbtable. The names of the BaseClassDescriptors have all of their fields 3591 // mangled into them so they can be aggressively deduplicated by the linker. 3592 3593 static llvm::GlobalVariable *getTypeInfoVTable(CodeGenModule &CGM) { 3594 StringRef MangledName("??_7type_info@@6B@"); 3595 if (auto VTable = CGM.getModule().getNamedGlobal(MangledName)) 3596 return VTable; 3597 return new llvm::GlobalVariable(CGM.getModule(), CGM.Int8PtrTy, 3598 /*isConstant=*/true, 3599 llvm::GlobalVariable::ExternalLinkage, 3600 /*Initializer=*/nullptr, MangledName); 3601 } 3602 3603 namespace { 3604 3605 /// A Helper struct that stores information about a class in a class 3606 /// hierarchy. The information stored in these structs struct is used during 3607 /// the generation of ClassHierarchyDescriptors and BaseClassDescriptors. 3608 // During RTTI creation, MSRTTIClasses are stored in a contiguous array with 3609 // implicit depth first pre-order tree connectivity. getFirstChild and 3610 // getNextSibling allow us to walk the tree efficiently. 3611 struct MSRTTIClass { 3612 enum { 3613 IsPrivateOnPath = 1 | 8, 3614 IsAmbiguous = 2, 3615 IsPrivate = 4, 3616 IsVirtual = 16, 3617 HasHierarchyDescriptor = 64 3618 }; 3619 MSRTTIClass(const CXXRecordDecl *RD) : RD(RD) {} 3620 uint32_t initialize(const MSRTTIClass *Parent, 3621 const CXXBaseSpecifier *Specifier); 3622 3623 MSRTTIClass *getFirstChild() { return this + 1; } 3624 static MSRTTIClass *getNextChild(MSRTTIClass *Child) { 3625 return Child + 1 + Child->NumBases; 3626 } 3627 3628 const CXXRecordDecl *RD, *VirtualRoot; 3629 uint32_t Flags, NumBases, OffsetInVBase; 3630 }; 3631 3632 /// Recursively initialize the base class array. 3633 uint32_t MSRTTIClass::initialize(const MSRTTIClass *Parent, 3634 const CXXBaseSpecifier *Specifier) { 3635 Flags = HasHierarchyDescriptor; 3636 if (!Parent) { 3637 VirtualRoot = nullptr; 3638 OffsetInVBase = 0; 3639 } else { 3640 if (Specifier->getAccessSpecifier() != AS_public) 3641 Flags |= IsPrivate | IsPrivateOnPath; 3642 if (Specifier->isVirtual()) { 3643 Flags |= IsVirtual; 3644 VirtualRoot = RD; 3645 OffsetInVBase = 0; 3646 } else { 3647 if (Parent->Flags & IsPrivateOnPath) 3648 Flags |= IsPrivateOnPath; 3649 VirtualRoot = Parent->VirtualRoot; 3650 OffsetInVBase = Parent->OffsetInVBase + RD->getASTContext() 3651 .getASTRecordLayout(Parent->RD).getBaseClassOffset(RD).getQuantity(); 3652 } 3653 } 3654 NumBases = 0; 3655 MSRTTIClass *Child = getFirstChild(); 3656 for (const CXXBaseSpecifier &Base : RD->bases()) { 3657 NumBases += Child->initialize(this, &Base) + 1; 3658 Child = getNextChild(Child); 3659 } 3660 return NumBases; 3661 } 3662 3663 static llvm::GlobalValue::LinkageTypes getLinkageForRTTI(QualType Ty) { 3664 switch (Ty->getLinkage()) { 3665 case Linkage::Invalid: 3666 llvm_unreachable("Linkage hasn't been computed!"); 3667 3668 case Linkage::None: 3669 case Linkage::Internal: 3670 case Linkage::UniqueExternal: 3671 return llvm::GlobalValue::InternalLinkage; 3672 3673 case Linkage::VisibleNone: 3674 case Linkage::Module: 3675 case Linkage::External: 3676 return llvm::GlobalValue::LinkOnceODRLinkage; 3677 } 3678 llvm_unreachable("Invalid linkage!"); 3679 } 3680 3681 /// An ephemeral helper class for building MS RTTI types. It caches some 3682 /// calls to the module and information about the most derived class in a 3683 /// hierarchy. 3684 struct MSRTTIBuilder { 3685 enum { 3686 HasBranchingHierarchy = 1, 3687 HasVirtualBranchingHierarchy = 2, 3688 HasAmbiguousBases = 4 3689 }; 3690 3691 MSRTTIBuilder(MicrosoftCXXABI &ABI, const CXXRecordDecl *RD) 3692 : CGM(ABI.CGM), Context(CGM.getContext()), 3693 VMContext(CGM.getLLVMContext()), Module(CGM.getModule()), RD(RD), 3694 Linkage(getLinkageForRTTI(CGM.getContext().getTagDeclType(RD))), 3695 ABI(ABI) {} 3696 3697 llvm::GlobalVariable *getBaseClassDescriptor(const MSRTTIClass &Classes); 3698 llvm::GlobalVariable * 3699 getBaseClassArray(SmallVectorImpl<MSRTTIClass> &Classes); 3700 llvm::GlobalVariable *getClassHierarchyDescriptor(); 3701 llvm::GlobalVariable *getCompleteObjectLocator(const VPtrInfo &Info); 3702 3703 CodeGenModule &CGM; 3704 ASTContext &Context; 3705 llvm::LLVMContext &VMContext; 3706 llvm::Module &Module; 3707 const CXXRecordDecl *RD; 3708 llvm::GlobalVariable::LinkageTypes Linkage; 3709 MicrosoftCXXABI &ABI; 3710 }; 3711 3712 } // namespace 3713 3714 /// Recursively serializes a class hierarchy in pre-order depth first 3715 /// order. 3716 static void serializeClassHierarchy(SmallVectorImpl<MSRTTIClass> &Classes, 3717 const CXXRecordDecl *RD) { 3718 Classes.push_back(MSRTTIClass(RD)); 3719 for (const CXXBaseSpecifier &Base : RD->bases()) 3720 serializeClassHierarchy(Classes, Base.getType()->getAsCXXRecordDecl()); 3721 } 3722 3723 /// Find ambiguity among base classes. 3724 static void 3725 detectAmbiguousBases(SmallVectorImpl<MSRTTIClass> &Classes) { 3726 llvm::SmallPtrSet<const CXXRecordDecl *, 8> VirtualBases; 3727 llvm::SmallPtrSet<const CXXRecordDecl *, 8> UniqueBases; 3728 llvm::SmallPtrSet<const CXXRecordDecl *, 8> AmbiguousBases; 3729 for (MSRTTIClass *Class = &Classes.front(); Class <= &Classes.back();) { 3730 if ((Class->Flags & MSRTTIClass::IsVirtual) && 3731 !VirtualBases.insert(Class->RD).second) { 3732 Class = MSRTTIClass::getNextChild(Class); 3733 continue; 3734 } 3735 if (!UniqueBases.insert(Class->RD).second) 3736 AmbiguousBases.insert(Class->RD); 3737 Class++; 3738 } 3739 if (AmbiguousBases.empty()) 3740 return; 3741 for (MSRTTIClass &Class : Classes) 3742 if (AmbiguousBases.count(Class.RD)) 3743 Class.Flags |= MSRTTIClass::IsAmbiguous; 3744 } 3745 3746 llvm::GlobalVariable *MSRTTIBuilder::getClassHierarchyDescriptor() { 3747 SmallString<256> MangledName; 3748 { 3749 llvm::raw_svector_ostream Out(MangledName); 3750 ABI.getMangleContext().mangleCXXRTTIClassHierarchyDescriptor(RD, Out); 3751 } 3752 3753 // Check to see if we've already declared this ClassHierarchyDescriptor. 3754 if (auto CHD = Module.getNamedGlobal(MangledName)) 3755 return CHD; 3756 3757 // Serialize the class hierarchy and initialize the CHD Fields. 3758 SmallVector<MSRTTIClass, 8> Classes; 3759 serializeClassHierarchy(Classes, RD); 3760 Classes.front().initialize(/*Parent=*/nullptr, /*Specifier=*/nullptr); 3761 detectAmbiguousBases(Classes); 3762 int Flags = 0; 3763 for (const MSRTTIClass &Class : Classes) { 3764 if (Class.RD->getNumBases() > 1) 3765 Flags |= HasBranchingHierarchy; 3766 // Note: cl.exe does not calculate "HasAmbiguousBases" correctly. We 3767 // believe the field isn't actually used. 3768 if (Class.Flags & MSRTTIClass::IsAmbiguous) 3769 Flags |= HasAmbiguousBases; 3770 } 3771 if ((Flags & HasBranchingHierarchy) && RD->getNumVBases() != 0) 3772 Flags |= HasVirtualBranchingHierarchy; 3773 // These gep indices are used to get the address of the first element of the 3774 // base class array. 3775 llvm::Value *GEPIndices[] = {llvm::ConstantInt::get(CGM.IntTy, 0), 3776 llvm::ConstantInt::get(CGM.IntTy, 0)}; 3777 3778 // Forward-declare the class hierarchy descriptor 3779 auto Type = ABI.getClassHierarchyDescriptorType(); 3780 auto CHD = new llvm::GlobalVariable(Module, Type, /*isConstant=*/true, Linkage, 3781 /*Initializer=*/nullptr, 3782 MangledName); 3783 if (CHD->isWeakForLinker()) 3784 CHD->setComdat(CGM.getModule().getOrInsertComdat(CHD->getName())); 3785 3786 auto *Bases = getBaseClassArray(Classes); 3787 3788 // Initialize the base class ClassHierarchyDescriptor. 3789 llvm::Constant *Fields[] = { 3790 llvm::ConstantInt::get(CGM.IntTy, 0), // reserved by the runtime 3791 llvm::ConstantInt::get(CGM.IntTy, Flags), 3792 llvm::ConstantInt::get(CGM.IntTy, Classes.size()), 3793 ABI.getImageRelativeConstant(llvm::ConstantExpr::getInBoundsGetElementPtr( 3794 Bases->getValueType(), Bases, 3795 llvm::ArrayRef<llvm::Value *>(GEPIndices))), 3796 }; 3797 CHD->setInitializer(llvm::ConstantStruct::get(Type, Fields)); 3798 return CHD; 3799 } 3800 3801 llvm::GlobalVariable * 3802 MSRTTIBuilder::getBaseClassArray(SmallVectorImpl<MSRTTIClass> &Classes) { 3803 SmallString<256> MangledName; 3804 { 3805 llvm::raw_svector_ostream Out(MangledName); 3806 ABI.getMangleContext().mangleCXXRTTIBaseClassArray(RD, Out); 3807 } 3808 3809 // Forward-declare the base class array. 3810 // cl.exe pads the base class array with 1 (in 32 bit mode) or 4 (in 64 bit 3811 // mode) bytes of padding. We provide a pointer sized amount of padding by 3812 // adding +1 to Classes.size(). The sections have pointer alignment and are 3813 // marked pick-any so it shouldn't matter. 3814 llvm::Type *PtrType = ABI.getImageRelativeType( 3815 ABI.getBaseClassDescriptorType()->getPointerTo()); 3816 auto *ArrType = llvm::ArrayType::get(PtrType, Classes.size() + 1); 3817 auto *BCA = 3818 new llvm::GlobalVariable(Module, ArrType, 3819 /*isConstant=*/true, Linkage, 3820 /*Initializer=*/nullptr, MangledName); 3821 if (BCA->isWeakForLinker()) 3822 BCA->setComdat(CGM.getModule().getOrInsertComdat(BCA->getName())); 3823 3824 // Initialize the BaseClassArray. 3825 SmallVector<llvm::Constant *, 8> BaseClassArrayData; 3826 for (MSRTTIClass &Class : Classes) 3827 BaseClassArrayData.push_back( 3828 ABI.getImageRelativeConstant(getBaseClassDescriptor(Class))); 3829 BaseClassArrayData.push_back(llvm::Constant::getNullValue(PtrType)); 3830 BCA->setInitializer(llvm::ConstantArray::get(ArrType, BaseClassArrayData)); 3831 return BCA; 3832 } 3833 3834 llvm::GlobalVariable * 3835 MSRTTIBuilder::getBaseClassDescriptor(const MSRTTIClass &Class) { 3836 // Compute the fields for the BaseClassDescriptor. They are computed up front 3837 // because they are mangled into the name of the object. 3838 uint32_t OffsetInVBTable = 0; 3839 int32_t VBPtrOffset = -1; 3840 if (Class.VirtualRoot) { 3841 auto &VTableContext = CGM.getMicrosoftVTableContext(); 3842 OffsetInVBTable = VTableContext.getVBTableIndex(RD, Class.VirtualRoot) * 4; 3843 VBPtrOffset = Context.getASTRecordLayout(RD).getVBPtrOffset().getQuantity(); 3844 } 3845 3846 SmallString<256> MangledName; 3847 { 3848 llvm::raw_svector_ostream Out(MangledName); 3849 ABI.getMangleContext().mangleCXXRTTIBaseClassDescriptor( 3850 Class.RD, Class.OffsetInVBase, VBPtrOffset, OffsetInVBTable, 3851 Class.Flags, Out); 3852 } 3853 3854 // Check to see if we've already declared this object. 3855 if (auto BCD = Module.getNamedGlobal(MangledName)) 3856 return BCD; 3857 3858 // Forward-declare the base class descriptor. 3859 auto Type = ABI.getBaseClassDescriptorType(); 3860 auto BCD = 3861 new llvm::GlobalVariable(Module, Type, /*isConstant=*/true, Linkage, 3862 /*Initializer=*/nullptr, MangledName); 3863 if (BCD->isWeakForLinker()) 3864 BCD->setComdat(CGM.getModule().getOrInsertComdat(BCD->getName())); 3865 3866 // Initialize the BaseClassDescriptor. 3867 llvm::Constant *Fields[] = { 3868 ABI.getImageRelativeConstant( 3869 ABI.getAddrOfRTTIDescriptor(Context.getTypeDeclType(Class.RD))), 3870 llvm::ConstantInt::get(CGM.IntTy, Class.NumBases), 3871 llvm::ConstantInt::get(CGM.IntTy, Class.OffsetInVBase), 3872 llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset), 3873 llvm::ConstantInt::get(CGM.IntTy, OffsetInVBTable), 3874 llvm::ConstantInt::get(CGM.IntTy, Class.Flags), 3875 ABI.getImageRelativeConstant( 3876 MSRTTIBuilder(ABI, Class.RD).getClassHierarchyDescriptor()), 3877 }; 3878 BCD->setInitializer(llvm::ConstantStruct::get(Type, Fields)); 3879 return BCD; 3880 } 3881 3882 llvm::GlobalVariable * 3883 MSRTTIBuilder::getCompleteObjectLocator(const VPtrInfo &Info) { 3884 SmallString<256> MangledName; 3885 { 3886 llvm::raw_svector_ostream Out(MangledName); 3887 ABI.getMangleContext().mangleCXXRTTICompleteObjectLocator(RD, Info.MangledPath, Out); 3888 } 3889 3890 // Check to see if we've already computed this complete object locator. 3891 if (auto COL = Module.getNamedGlobal(MangledName)) 3892 return COL; 3893 3894 // Compute the fields of the complete object locator. 3895 int OffsetToTop = Info.FullOffsetInMDC.getQuantity(); 3896 int VFPtrOffset = 0; 3897 // The offset includes the vtordisp if one exists. 3898 if (const CXXRecordDecl *VBase = Info.getVBaseWithVPtr()) 3899 if (Context.getASTRecordLayout(RD) 3900 .getVBaseOffsetsMap() 3901 .find(VBase) 3902 ->second.hasVtorDisp()) 3903 VFPtrOffset = Info.NonVirtualOffset.getQuantity() + 4; 3904 3905 // Forward-declare the complete object locator. 3906 llvm::StructType *Type = ABI.getCompleteObjectLocatorType(); 3907 auto COL = new llvm::GlobalVariable(Module, Type, /*isConstant=*/true, Linkage, 3908 /*Initializer=*/nullptr, MangledName); 3909 3910 // Initialize the CompleteObjectLocator. 3911 llvm::Constant *Fields[] = { 3912 llvm::ConstantInt::get(CGM.IntTy, ABI.isImageRelative()), 3913 llvm::ConstantInt::get(CGM.IntTy, OffsetToTop), 3914 llvm::ConstantInt::get(CGM.IntTy, VFPtrOffset), 3915 ABI.getImageRelativeConstant( 3916 CGM.GetAddrOfRTTIDescriptor(Context.getTypeDeclType(RD))), 3917 ABI.getImageRelativeConstant(getClassHierarchyDescriptor()), 3918 ABI.getImageRelativeConstant(COL), 3919 }; 3920 llvm::ArrayRef<llvm::Constant *> FieldsRef(Fields); 3921 if (!ABI.isImageRelative()) 3922 FieldsRef = FieldsRef.drop_back(); 3923 COL->setInitializer(llvm::ConstantStruct::get(Type, FieldsRef)); 3924 if (COL->isWeakForLinker()) 3925 COL->setComdat(CGM.getModule().getOrInsertComdat(COL->getName())); 3926 return COL; 3927 } 3928 3929 static QualType decomposeTypeForEH(ASTContext &Context, QualType T, 3930 bool &IsConst, bool &IsVolatile, 3931 bool &IsUnaligned) { 3932 T = Context.getExceptionObjectType(T); 3933 3934 // C++14 [except.handle]p3: 3935 // A handler is a match for an exception object of type E if [...] 3936 // - the handler is of type cv T or const T& where T is a pointer type and 3937 // E is a pointer type that can be converted to T by [...] 3938 // - a qualification conversion 3939 IsConst = false; 3940 IsVolatile = false; 3941 IsUnaligned = false; 3942 QualType PointeeType = T->getPointeeType(); 3943 if (!PointeeType.isNull()) { 3944 IsConst = PointeeType.isConstQualified(); 3945 IsVolatile = PointeeType.isVolatileQualified(); 3946 IsUnaligned = PointeeType.getQualifiers().hasUnaligned(); 3947 } 3948 3949 // Member pointer types like "const int A::*" are represented by having RTTI 3950 // for "int A::*" and separately storing the const qualifier. 3951 if (const auto *MPTy = T->getAs<MemberPointerType>()) 3952 T = Context.getMemberPointerType(PointeeType.getUnqualifiedType(), 3953 MPTy->getClass()); 3954 3955 // Pointer types like "const int * const *" are represented by having RTTI 3956 // for "const int **" and separately storing the const qualifier. 3957 if (T->isPointerType()) 3958 T = Context.getPointerType(PointeeType.getUnqualifiedType()); 3959 3960 return T; 3961 } 3962 3963 CatchTypeInfo 3964 MicrosoftCXXABI::getAddrOfCXXCatchHandlerType(QualType Type, 3965 QualType CatchHandlerType) { 3966 // TypeDescriptors for exceptions never have qualified pointer types, 3967 // qualifiers are stored separately in order to support qualification 3968 // conversions. 3969 bool IsConst, IsVolatile, IsUnaligned; 3970 Type = 3971 decomposeTypeForEH(getContext(), Type, IsConst, IsVolatile, IsUnaligned); 3972 3973 bool IsReference = CatchHandlerType->isReferenceType(); 3974 3975 uint32_t Flags = 0; 3976 if (IsConst) 3977 Flags |= 1; 3978 if (IsVolatile) 3979 Flags |= 2; 3980 if (IsUnaligned) 3981 Flags |= 4; 3982 if (IsReference) 3983 Flags |= 8; 3984 3985 return CatchTypeInfo{getAddrOfRTTIDescriptor(Type)->stripPointerCasts(), 3986 Flags}; 3987 } 3988 3989 /// Gets a TypeDescriptor. Returns a llvm::Constant * rather than a 3990 /// llvm::GlobalVariable * because different type descriptors have different 3991 /// types, and need to be abstracted. They are abstracting by casting the 3992 /// address to an Int8PtrTy. 3993 llvm::Constant *MicrosoftCXXABI::getAddrOfRTTIDescriptor(QualType Type) { 3994 SmallString<256> MangledName; 3995 { 3996 llvm::raw_svector_ostream Out(MangledName); 3997 getMangleContext().mangleCXXRTTI(Type, Out); 3998 } 3999 4000 // Check to see if we've already declared this TypeDescriptor. 4001 if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName)) 4002 return GV; 4003 4004 // Note for the future: If we would ever like to do deferred emission of 4005 // RTTI, check if emitting vtables opportunistically need any adjustment. 4006 4007 // Compute the fields for the TypeDescriptor. 4008 SmallString<256> TypeInfoString; 4009 { 4010 llvm::raw_svector_ostream Out(TypeInfoString); 4011 getMangleContext().mangleCXXRTTIName(Type, Out); 4012 } 4013 4014 // Declare and initialize the TypeDescriptor. 4015 llvm::Constant *Fields[] = { 4016 getTypeInfoVTable(CGM), // VFPtr 4017 llvm::ConstantPointerNull::get(CGM.Int8PtrTy), // Runtime data 4018 llvm::ConstantDataArray::getString(CGM.getLLVMContext(), TypeInfoString)}; 4019 llvm::StructType *TypeDescriptorType = 4020 getTypeDescriptorType(TypeInfoString); 4021 auto *Var = new llvm::GlobalVariable( 4022 CGM.getModule(), TypeDescriptorType, /*isConstant=*/false, 4023 getLinkageForRTTI(Type), 4024 llvm::ConstantStruct::get(TypeDescriptorType, Fields), 4025 MangledName); 4026 if (Var->isWeakForLinker()) 4027 Var->setComdat(CGM.getModule().getOrInsertComdat(Var->getName())); 4028 return Var; 4029 } 4030 4031 /// Gets or a creates a Microsoft CompleteObjectLocator. 4032 llvm::GlobalVariable * 4033 MicrosoftCXXABI::getMSCompleteObjectLocator(const CXXRecordDecl *RD, 4034 const VPtrInfo &Info) { 4035 return MSRTTIBuilder(*this, RD).getCompleteObjectLocator(Info); 4036 } 4037 4038 void MicrosoftCXXABI::emitCXXStructor(GlobalDecl GD) { 4039 if (auto *ctor = dyn_cast<CXXConstructorDecl>(GD.getDecl())) { 4040 // There are no constructor variants, always emit the complete destructor. 4041 llvm::Function *Fn = 4042 CGM.codegenCXXStructor(GD.getWithCtorType(Ctor_Complete)); 4043 CGM.maybeSetTrivialComdat(*ctor, *Fn); 4044 return; 4045 } 4046 4047 auto *dtor = cast<CXXDestructorDecl>(GD.getDecl()); 4048 4049 // Emit the base destructor if the base and complete (vbase) destructors are 4050 // equivalent. This effectively implements -mconstructor-aliases as part of 4051 // the ABI. 4052 if (GD.getDtorType() == Dtor_Complete && 4053 dtor->getParent()->getNumVBases() == 0) 4054 GD = GD.getWithDtorType(Dtor_Base); 4055 4056 // The base destructor is equivalent to the base destructor of its 4057 // base class if there is exactly one non-virtual base class with a 4058 // non-trivial destructor, there are no fields with a non-trivial 4059 // destructor, and the body of the destructor is trivial. 4060 if (GD.getDtorType() == Dtor_Base && !CGM.TryEmitBaseDestructorAsAlias(dtor)) 4061 return; 4062 4063 llvm::Function *Fn = CGM.codegenCXXStructor(GD); 4064 if (Fn->isWeakForLinker()) 4065 Fn->setComdat(CGM.getModule().getOrInsertComdat(Fn->getName())); 4066 } 4067 4068 llvm::Function * 4069 MicrosoftCXXABI::getAddrOfCXXCtorClosure(const CXXConstructorDecl *CD, 4070 CXXCtorType CT) { 4071 assert(CT == Ctor_CopyingClosure || CT == Ctor_DefaultClosure); 4072 4073 // Calculate the mangled name. 4074 SmallString<256> ThunkName; 4075 llvm::raw_svector_ostream Out(ThunkName); 4076 getMangleContext().mangleName(GlobalDecl(CD, CT), Out); 4077 4078 // If the thunk has been generated previously, just return it. 4079 if (llvm::GlobalValue *GV = CGM.getModule().getNamedValue(ThunkName)) 4080 return cast<llvm::Function>(GV); 4081 4082 // Create the llvm::Function. 4083 const CGFunctionInfo &FnInfo = CGM.getTypes().arrangeMSCtorClosure(CD, CT); 4084 llvm::FunctionType *ThunkTy = CGM.getTypes().GetFunctionType(FnInfo); 4085 const CXXRecordDecl *RD = CD->getParent(); 4086 QualType RecordTy = getContext().getRecordType(RD); 4087 llvm::Function *ThunkFn = llvm::Function::Create( 4088 ThunkTy, getLinkageForRTTI(RecordTy), ThunkName.str(), &CGM.getModule()); 4089 ThunkFn->setCallingConv(static_cast<llvm::CallingConv::ID>( 4090 FnInfo.getEffectiveCallingConvention())); 4091 if (ThunkFn->isWeakForLinker()) 4092 ThunkFn->setComdat(CGM.getModule().getOrInsertComdat(ThunkFn->getName())); 4093 bool IsCopy = CT == Ctor_CopyingClosure; 4094 4095 // Start codegen. 4096 CodeGenFunction CGF(CGM); 4097 CGF.CurGD = GlobalDecl(CD, Ctor_Complete); 4098 4099 // Build FunctionArgs. 4100 FunctionArgList FunctionArgs; 4101 4102 // A constructor always starts with a 'this' pointer as its first argument. 4103 buildThisParam(CGF, FunctionArgs); 4104 4105 // Following the 'this' pointer is a reference to the source object that we 4106 // are copying from. 4107 ImplicitParamDecl SrcParam( 4108 getContext(), /*DC=*/nullptr, SourceLocation(), 4109 &getContext().Idents.get("src"), 4110 getContext().getLValueReferenceType(RecordTy, 4111 /*SpelledAsLValue=*/true), 4112 ImplicitParamKind::Other); 4113 if (IsCopy) 4114 FunctionArgs.push_back(&SrcParam); 4115 4116 // Constructors for classes which utilize virtual bases have an additional 4117 // parameter which indicates whether or not it is being delegated to by a more 4118 // derived constructor. 4119 ImplicitParamDecl IsMostDerived(getContext(), /*DC=*/nullptr, 4120 SourceLocation(), 4121 &getContext().Idents.get("is_most_derived"), 4122 getContext().IntTy, ImplicitParamKind::Other); 4123 // Only add the parameter to the list if the class has virtual bases. 4124 if (RD->getNumVBases() > 0) 4125 FunctionArgs.push_back(&IsMostDerived); 4126 4127 // Start defining the function. 4128 auto NL = ApplyDebugLocation::CreateEmpty(CGF); 4129 CGF.StartFunction(GlobalDecl(), FnInfo.getReturnType(), ThunkFn, FnInfo, 4130 FunctionArgs, CD->getLocation(), SourceLocation()); 4131 // Create a scope with an artificial location for the body of this function. 4132 auto AL = ApplyDebugLocation::CreateArtificial(CGF); 4133 setCXXABIThisValue(CGF, loadIncomingCXXThis(CGF)); 4134 llvm::Value *This = getThisValue(CGF); 4135 4136 llvm::Value *SrcVal = 4137 IsCopy ? CGF.Builder.CreateLoad(CGF.GetAddrOfLocalVar(&SrcParam), "src") 4138 : nullptr; 4139 4140 CallArgList Args; 4141 4142 // Push the this ptr. 4143 Args.add(RValue::get(This), CD->getThisType()); 4144 4145 // Push the src ptr. 4146 if (SrcVal) 4147 Args.add(RValue::get(SrcVal), SrcParam.getType()); 4148 4149 // Add the rest of the default arguments. 4150 SmallVector<const Stmt *, 4> ArgVec; 4151 ArrayRef<ParmVarDecl *> params = CD->parameters().drop_front(IsCopy ? 1 : 0); 4152 for (const ParmVarDecl *PD : params) { 4153 assert(PD->hasDefaultArg() && "ctor closure lacks default args"); 4154 ArgVec.push_back(PD->getDefaultArg()); 4155 } 4156 4157 CodeGenFunction::RunCleanupsScope Cleanups(CGF); 4158 4159 const auto *FPT = CD->getType()->castAs<FunctionProtoType>(); 4160 CGF.EmitCallArgs(Args, FPT, llvm::ArrayRef(ArgVec), CD, IsCopy ? 1 : 0); 4161 4162 // Insert any ABI-specific implicit constructor arguments. 4163 AddedStructorArgCounts ExtraArgs = 4164 addImplicitConstructorArgs(CGF, CD, Ctor_Complete, 4165 /*ForVirtualBase=*/false, 4166 /*Delegating=*/false, Args); 4167 // Call the destructor with our arguments. 4168 llvm::Constant *CalleePtr = 4169 CGM.getAddrOfCXXStructor(GlobalDecl(CD, Ctor_Complete)); 4170 CGCallee Callee = 4171 CGCallee::forDirect(CalleePtr, GlobalDecl(CD, Ctor_Complete)); 4172 const CGFunctionInfo &CalleeInfo = CGM.getTypes().arrangeCXXConstructorCall( 4173 Args, CD, Ctor_Complete, ExtraArgs.Prefix, ExtraArgs.Suffix); 4174 CGF.EmitCall(CalleeInfo, Callee, ReturnValueSlot(), Args); 4175 4176 Cleanups.ForceCleanup(); 4177 4178 // Emit the ret instruction, remove any temporary instructions created for the 4179 // aid of CodeGen. 4180 CGF.FinishFunction(SourceLocation()); 4181 4182 return ThunkFn; 4183 } 4184 4185 llvm::Constant *MicrosoftCXXABI::getCatchableType(QualType T, 4186 uint32_t NVOffset, 4187 int32_t VBPtrOffset, 4188 uint32_t VBIndex) { 4189 assert(!T->isReferenceType()); 4190 4191 CXXRecordDecl *RD = T->getAsCXXRecordDecl(); 4192 const CXXConstructorDecl *CD = 4193 RD ? CGM.getContext().getCopyConstructorForExceptionObject(RD) : nullptr; 4194 CXXCtorType CT = Ctor_Complete; 4195 if (CD) 4196 if (!hasDefaultCXXMethodCC(getContext(), CD) || CD->getNumParams() != 1) 4197 CT = Ctor_CopyingClosure; 4198 4199 uint32_t Size = getContext().getTypeSizeInChars(T).getQuantity(); 4200 SmallString<256> MangledName; 4201 { 4202 llvm::raw_svector_ostream Out(MangledName); 4203 getMangleContext().mangleCXXCatchableType(T, CD, CT, Size, NVOffset, 4204 VBPtrOffset, VBIndex, Out); 4205 } 4206 if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName)) 4207 return getImageRelativeConstant(GV); 4208 4209 // The TypeDescriptor is used by the runtime to determine if a catch handler 4210 // is appropriate for the exception object. 4211 llvm::Constant *TD = getImageRelativeConstant(getAddrOfRTTIDescriptor(T)); 4212 4213 // The runtime is responsible for calling the copy constructor if the 4214 // exception is caught by value. 4215 llvm::Constant *CopyCtor; 4216 if (CD) { 4217 if (CT == Ctor_CopyingClosure) 4218 CopyCtor = getAddrOfCXXCtorClosure(CD, Ctor_CopyingClosure); 4219 else 4220 CopyCtor = CGM.getAddrOfCXXStructor(GlobalDecl(CD, Ctor_Complete)); 4221 } else { 4222 CopyCtor = llvm::Constant::getNullValue(CGM.Int8PtrTy); 4223 } 4224 CopyCtor = getImageRelativeConstant(CopyCtor); 4225 4226 bool IsScalar = !RD; 4227 bool HasVirtualBases = false; 4228 bool IsStdBadAlloc = false; // std::bad_alloc is special for some reason. 4229 QualType PointeeType = T; 4230 if (T->isPointerType()) 4231 PointeeType = T->getPointeeType(); 4232 if (const CXXRecordDecl *RD = PointeeType->getAsCXXRecordDecl()) { 4233 HasVirtualBases = RD->getNumVBases() > 0; 4234 if (IdentifierInfo *II = RD->getIdentifier()) 4235 IsStdBadAlloc = II->isStr("bad_alloc") && RD->isInStdNamespace(); 4236 } 4237 4238 // Encode the relevant CatchableType properties into the Flags bitfield. 4239 // FIXME: Figure out how bits 2 or 8 can get set. 4240 uint32_t Flags = 0; 4241 if (IsScalar) 4242 Flags |= 1; 4243 if (HasVirtualBases) 4244 Flags |= 4; 4245 if (IsStdBadAlloc) 4246 Flags |= 16; 4247 4248 llvm::Constant *Fields[] = { 4249 llvm::ConstantInt::get(CGM.IntTy, Flags), // Flags 4250 TD, // TypeDescriptor 4251 llvm::ConstantInt::get(CGM.IntTy, NVOffset), // NonVirtualAdjustment 4252 llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset), // OffsetToVBPtr 4253 llvm::ConstantInt::get(CGM.IntTy, VBIndex), // VBTableIndex 4254 llvm::ConstantInt::get(CGM.IntTy, Size), // Size 4255 CopyCtor // CopyCtor 4256 }; 4257 llvm::StructType *CTType = getCatchableTypeType(); 4258 auto *GV = new llvm::GlobalVariable( 4259 CGM.getModule(), CTType, /*isConstant=*/true, getLinkageForRTTI(T), 4260 llvm::ConstantStruct::get(CTType, Fields), MangledName); 4261 GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global); 4262 GV->setSection(".xdata"); 4263 if (GV->isWeakForLinker()) 4264 GV->setComdat(CGM.getModule().getOrInsertComdat(GV->getName())); 4265 return getImageRelativeConstant(GV); 4266 } 4267 4268 llvm::GlobalVariable *MicrosoftCXXABI::getCatchableTypeArray(QualType T) { 4269 assert(!T->isReferenceType()); 4270 4271 // See if we've already generated a CatchableTypeArray for this type before. 4272 llvm::GlobalVariable *&CTA = CatchableTypeArrays[T]; 4273 if (CTA) 4274 return CTA; 4275 4276 // Ensure that we don't have duplicate entries in our CatchableTypeArray by 4277 // using a SmallSetVector. Duplicates may arise due to virtual bases 4278 // occurring more than once in the hierarchy. 4279 llvm::SmallSetVector<llvm::Constant *, 2> CatchableTypes; 4280 4281 // C++14 [except.handle]p3: 4282 // A handler is a match for an exception object of type E if [...] 4283 // - the handler is of type cv T or cv T& and T is an unambiguous public 4284 // base class of E, or 4285 // - the handler is of type cv T or const T& where T is a pointer type and 4286 // E is a pointer type that can be converted to T by [...] 4287 // - a standard pointer conversion (4.10) not involving conversions to 4288 // pointers to private or protected or ambiguous classes 4289 const CXXRecordDecl *MostDerivedClass = nullptr; 4290 bool IsPointer = T->isPointerType(); 4291 if (IsPointer) 4292 MostDerivedClass = T->getPointeeType()->getAsCXXRecordDecl(); 4293 else 4294 MostDerivedClass = T->getAsCXXRecordDecl(); 4295 4296 // Collect all the unambiguous public bases of the MostDerivedClass. 4297 if (MostDerivedClass) { 4298 const ASTContext &Context = getContext(); 4299 const ASTRecordLayout &MostDerivedLayout = 4300 Context.getASTRecordLayout(MostDerivedClass); 4301 MicrosoftVTableContext &VTableContext = CGM.getMicrosoftVTableContext(); 4302 SmallVector<MSRTTIClass, 8> Classes; 4303 serializeClassHierarchy(Classes, MostDerivedClass); 4304 Classes.front().initialize(/*Parent=*/nullptr, /*Specifier=*/nullptr); 4305 detectAmbiguousBases(Classes); 4306 for (const MSRTTIClass &Class : Classes) { 4307 // Skip any ambiguous or private bases. 4308 if (Class.Flags & 4309 (MSRTTIClass::IsPrivateOnPath | MSRTTIClass::IsAmbiguous)) 4310 continue; 4311 // Write down how to convert from a derived pointer to a base pointer. 4312 uint32_t OffsetInVBTable = 0; 4313 int32_t VBPtrOffset = -1; 4314 if (Class.VirtualRoot) { 4315 OffsetInVBTable = 4316 VTableContext.getVBTableIndex(MostDerivedClass, Class.VirtualRoot)*4; 4317 VBPtrOffset = MostDerivedLayout.getVBPtrOffset().getQuantity(); 4318 } 4319 4320 // Turn our record back into a pointer if the exception object is a 4321 // pointer. 4322 QualType RTTITy = QualType(Class.RD->getTypeForDecl(), 0); 4323 if (IsPointer) 4324 RTTITy = Context.getPointerType(RTTITy); 4325 CatchableTypes.insert(getCatchableType(RTTITy, Class.OffsetInVBase, 4326 VBPtrOffset, OffsetInVBTable)); 4327 } 4328 } 4329 4330 // C++14 [except.handle]p3: 4331 // A handler is a match for an exception object of type E if 4332 // - The handler is of type cv T or cv T& and E and T are the same type 4333 // (ignoring the top-level cv-qualifiers) 4334 CatchableTypes.insert(getCatchableType(T)); 4335 4336 // C++14 [except.handle]p3: 4337 // A handler is a match for an exception object of type E if 4338 // - the handler is of type cv T or const T& where T is a pointer type and 4339 // E is a pointer type that can be converted to T by [...] 4340 // - a standard pointer conversion (4.10) not involving conversions to 4341 // pointers to private or protected or ambiguous classes 4342 // 4343 // C++14 [conv.ptr]p2: 4344 // A prvalue of type "pointer to cv T," where T is an object type, can be 4345 // converted to a prvalue of type "pointer to cv void". 4346 if (IsPointer && T->getPointeeType()->isObjectType()) 4347 CatchableTypes.insert(getCatchableType(getContext().VoidPtrTy)); 4348 4349 // C++14 [except.handle]p3: 4350 // A handler is a match for an exception object of type E if [...] 4351 // - the handler is of type cv T or const T& where T is a pointer or 4352 // pointer to member type and E is std::nullptr_t. 4353 // 4354 // We cannot possibly list all possible pointer types here, making this 4355 // implementation incompatible with the standard. However, MSVC includes an 4356 // entry for pointer-to-void in this case. Let's do the same. 4357 if (T->isNullPtrType()) 4358 CatchableTypes.insert(getCatchableType(getContext().VoidPtrTy)); 4359 4360 uint32_t NumEntries = CatchableTypes.size(); 4361 llvm::Type *CTType = 4362 getImageRelativeType(getCatchableTypeType()->getPointerTo()); 4363 llvm::ArrayType *AT = llvm::ArrayType::get(CTType, NumEntries); 4364 llvm::StructType *CTAType = getCatchableTypeArrayType(NumEntries); 4365 llvm::Constant *Fields[] = { 4366 llvm::ConstantInt::get(CGM.IntTy, NumEntries), // NumEntries 4367 llvm::ConstantArray::get( 4368 AT, llvm::ArrayRef(CatchableTypes.begin(), 4369 CatchableTypes.end())) // CatchableTypes 4370 }; 4371 SmallString<256> MangledName; 4372 { 4373 llvm::raw_svector_ostream Out(MangledName); 4374 getMangleContext().mangleCXXCatchableTypeArray(T, NumEntries, Out); 4375 } 4376 CTA = new llvm::GlobalVariable( 4377 CGM.getModule(), CTAType, /*isConstant=*/true, getLinkageForRTTI(T), 4378 llvm::ConstantStruct::get(CTAType, Fields), MangledName); 4379 CTA->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global); 4380 CTA->setSection(".xdata"); 4381 if (CTA->isWeakForLinker()) 4382 CTA->setComdat(CGM.getModule().getOrInsertComdat(CTA->getName())); 4383 return CTA; 4384 } 4385 4386 llvm::GlobalVariable *MicrosoftCXXABI::getThrowInfo(QualType T) { 4387 bool IsConst, IsVolatile, IsUnaligned; 4388 T = decomposeTypeForEH(getContext(), T, IsConst, IsVolatile, IsUnaligned); 4389 4390 // The CatchableTypeArray enumerates the various (CV-unqualified) types that 4391 // the exception object may be caught as. 4392 llvm::GlobalVariable *CTA = getCatchableTypeArray(T); 4393 // The first field in a CatchableTypeArray is the number of CatchableTypes. 4394 // This is used as a component of the mangled name which means that we need to 4395 // know what it is in order to see if we have previously generated the 4396 // ThrowInfo. 4397 uint32_t NumEntries = 4398 cast<llvm::ConstantInt>(CTA->getInitializer()->getAggregateElement(0U)) 4399 ->getLimitedValue(); 4400 4401 SmallString<256> MangledName; 4402 { 4403 llvm::raw_svector_ostream Out(MangledName); 4404 getMangleContext().mangleCXXThrowInfo(T, IsConst, IsVolatile, IsUnaligned, 4405 NumEntries, Out); 4406 } 4407 4408 // Reuse a previously generated ThrowInfo if we have generated an appropriate 4409 // one before. 4410 if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName)) 4411 return GV; 4412 4413 // The RTTI TypeDescriptor uses an unqualified type but catch clauses must 4414 // be at least as CV qualified. Encode this requirement into the Flags 4415 // bitfield. 4416 uint32_t Flags = 0; 4417 if (IsConst) 4418 Flags |= 1; 4419 if (IsVolatile) 4420 Flags |= 2; 4421 if (IsUnaligned) 4422 Flags |= 4; 4423 4424 // The cleanup-function (a destructor) must be called when the exception 4425 // object's lifetime ends. 4426 llvm::Constant *CleanupFn = llvm::Constant::getNullValue(CGM.Int8PtrTy); 4427 if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl()) 4428 if (CXXDestructorDecl *DtorD = RD->getDestructor()) 4429 if (!DtorD->isTrivial()) 4430 CleanupFn = CGM.getAddrOfCXXStructor(GlobalDecl(DtorD, Dtor_Complete)); 4431 // This is unused as far as we can tell, initialize it to null. 4432 llvm::Constant *ForwardCompat = 4433 getImageRelativeConstant(llvm::Constant::getNullValue(CGM.Int8PtrTy)); 4434 llvm::Constant *PointerToCatchableTypes = getImageRelativeConstant(CTA); 4435 llvm::StructType *TIType = getThrowInfoType(); 4436 llvm::Constant *Fields[] = { 4437 llvm::ConstantInt::get(CGM.IntTy, Flags), // Flags 4438 getImageRelativeConstant(CleanupFn), // CleanupFn 4439 ForwardCompat, // ForwardCompat 4440 PointerToCatchableTypes // CatchableTypeArray 4441 }; 4442 auto *GV = new llvm::GlobalVariable( 4443 CGM.getModule(), TIType, /*isConstant=*/true, getLinkageForRTTI(T), 4444 llvm::ConstantStruct::get(TIType, Fields), MangledName.str()); 4445 GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global); 4446 GV->setSection(".xdata"); 4447 if (GV->isWeakForLinker()) 4448 GV->setComdat(CGM.getModule().getOrInsertComdat(GV->getName())); 4449 return GV; 4450 } 4451 4452 void MicrosoftCXXABI::emitThrow(CodeGenFunction &CGF, const CXXThrowExpr *E) { 4453 const Expr *SubExpr = E->getSubExpr(); 4454 assert(SubExpr && "SubExpr cannot be null"); 4455 QualType ThrowType = SubExpr->getType(); 4456 // The exception object lives on the stack and it's address is passed to the 4457 // runtime function. 4458 Address AI = CGF.CreateMemTemp(ThrowType); 4459 CGF.EmitAnyExprToMem(SubExpr, AI, ThrowType.getQualifiers(), 4460 /*IsInit=*/true); 4461 4462 // The so-called ThrowInfo is used to describe how the exception object may be 4463 // caught. 4464 llvm::GlobalVariable *TI = getThrowInfo(ThrowType); 4465 4466 // Call into the runtime to throw the exception. 4467 llvm::Value *Args[] = {AI.emitRawPointer(CGF), TI}; 4468 CGF.EmitNoreturnRuntimeCallOrInvoke(getThrowFn(), Args); 4469 } 4470 4471 std::pair<llvm::Value *, const CXXRecordDecl *> 4472 MicrosoftCXXABI::LoadVTablePtr(CodeGenFunction &CGF, Address This, 4473 const CXXRecordDecl *RD) { 4474 std::tie(This, std::ignore, RD) = 4475 performBaseAdjustment(CGF, This, QualType(RD->getTypeForDecl(), 0)); 4476 return {CGF.GetVTablePtr(This, CGM.Int8PtrTy, RD), RD}; 4477 } 4478 4479 bool MicrosoftCXXABI::isPermittedToBeHomogeneousAggregate( 4480 const CXXRecordDecl *RD) const { 4481 // All aggregates are permitted to be HFA on non-ARM platforms, which mostly 4482 // affects vectorcall on x64/x86. 4483 if (!CGM.getTarget().getTriple().isAArch64()) 4484 return true; 4485 // MSVC Windows on Arm64 has its own rules for determining if a type is HFA 4486 // that are inconsistent with the AAPCS64 ABI. The following are our best 4487 // determination of those rules so far, based on observation of MSVC's 4488 // behavior. 4489 if (RD->isEmpty()) 4490 return false; 4491 if (RD->isPolymorphic()) 4492 return false; 4493 if (RD->hasNonTrivialCopyAssignment()) 4494 return false; 4495 if (RD->hasNonTrivialDestructor()) 4496 return false; 4497 if (RD->hasNonTrivialDefaultConstructor()) 4498 return false; 4499 // These two are somewhat redundant given the caller 4500 // (ABIInfo::isHomogeneousAggregate) checks the bases and fields, but that 4501 // caller doesn't consider empty bases/fields to be non-homogenous, but it 4502 // looks like Microsoft's AArch64 ABI does care about these empty types & 4503 // anything containing/derived from one is non-homogeneous. 4504 // Instead we could add another CXXABI entry point to query this property and 4505 // have ABIInfo::isHomogeneousAggregate use that property. 4506 // I don't think any other of the features listed above could be true of a 4507 // base/field while not true of the outer struct. For example, if you have a 4508 // base/field that has an non-trivial copy assignment/dtor/default ctor, then 4509 // the outer struct's corresponding operation must be non-trivial. 4510 for (const CXXBaseSpecifier &B : RD->bases()) { 4511 if (const CXXRecordDecl *FRD = B.getType()->getAsCXXRecordDecl()) { 4512 if (!isPermittedToBeHomogeneousAggregate(FRD)) 4513 return false; 4514 } 4515 } 4516 // empty fields seem to be caught by the ABIInfo::isHomogeneousAggregate 4517 // checking for padding - but maybe there are ways to end up with an empty 4518 // field without padding? Not that I know of, so don't check fields here & 4519 // rely on the padding check. 4520 return true; 4521 } 4522