MicrosoftCXXABI.cpp revision 280031
1//===--- MicrosoftCXXABI.cpp - Emit LLVM Code from ASTs for a Module ------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This provides C++ code generation targeting the Microsoft Visual C++ ABI. 11// The class in this file generates structures that follow the Microsoft 12// Visual C++ ABI, which is actually not very well documented at all outside 13// of Microsoft. 14// 15//===----------------------------------------------------------------------===// 16 17#include "CGCXXABI.h" 18#include "CGVTables.h" 19#include "CodeGenModule.h" 20#include "clang/AST/Decl.h" 21#include "clang/AST/DeclCXX.h" 22#include "clang/AST/VTableBuilder.h" 23#include "llvm/ADT/StringExtras.h" 24#include "llvm/ADT/StringSet.h" 25#include "llvm/IR/CallSite.h" 26 27using namespace clang; 28using namespace CodeGen; 29 30namespace { 31 32/// Holds all the vbtable globals for a given class. 33struct VBTableGlobals { 34 const VPtrInfoVector *VBTables; 35 SmallVector<llvm::GlobalVariable *, 2> Globals; 36}; 37 38class MicrosoftCXXABI : public CGCXXABI { 39public: 40 MicrosoftCXXABI(CodeGenModule &CGM) 41 : CGCXXABI(CGM), BaseClassDescriptorType(nullptr), 42 ClassHierarchyDescriptorType(nullptr), 43 CompleteObjectLocatorType(nullptr) {} 44 45 bool HasThisReturn(GlobalDecl GD) const override; 46 bool hasMostDerivedReturn(GlobalDecl GD) const override; 47 48 bool classifyReturnType(CGFunctionInfo &FI) const override; 49 50 RecordArgABI getRecordArgABI(const CXXRecordDecl *RD) const override; 51 52 bool isSRetParameterAfterThis() const override { return true; } 53 54 size_t getSrcArgforCopyCtor(const CXXConstructorDecl *CD, 55 FunctionArgList &Args) const override { 56 assert(Args.size() >= 2 && 57 "expected the arglist to have at least two args!"); 58 // The 'most_derived' parameter goes second if the ctor is variadic and 59 // has v-bases. 60 if (CD->getParent()->getNumVBases() > 0 && 61 CD->getType()->castAs<FunctionProtoType>()->isVariadic()) 62 return 2; 63 return 1; 64 } 65 66 StringRef GetPureVirtualCallName() override { return "_purecall"; } 67 StringRef GetDeletedVirtualCallName() override { return "_purecall"; } 68 69 void emitVirtualObjectDelete(CodeGenFunction &CGF, const CXXDeleteExpr *DE, 70 llvm::Value *Ptr, QualType ElementType, 71 const CXXDestructorDecl *Dtor) override; 72 73 void emitRethrow(CodeGenFunction &CGF, bool isNoReturn) override; 74 75 llvm::GlobalVariable *getMSCompleteObjectLocator(const CXXRecordDecl *RD, 76 const VPtrInfo *Info); 77 78 llvm::Constant *getAddrOfRTTIDescriptor(QualType Ty) override; 79 80 bool shouldTypeidBeNullChecked(bool IsDeref, QualType SrcRecordTy) override; 81 void EmitBadTypeidCall(CodeGenFunction &CGF) override; 82 llvm::Value *EmitTypeid(CodeGenFunction &CGF, QualType SrcRecordTy, 83 llvm::Value *ThisPtr, 84 llvm::Type *StdTypeInfoPtrTy) override; 85 86 bool shouldDynamicCastCallBeNullChecked(bool SrcIsPtr, 87 QualType SrcRecordTy) override; 88 89 llvm::Value *EmitDynamicCastCall(CodeGenFunction &CGF, llvm::Value *Value, 90 QualType SrcRecordTy, QualType DestTy, 91 QualType DestRecordTy, 92 llvm::BasicBlock *CastEnd) override; 93 94 llvm::Value *EmitDynamicCastToVoid(CodeGenFunction &CGF, llvm::Value *Value, 95 QualType SrcRecordTy, 96 QualType DestTy) override; 97 98 bool EmitBadCastCall(CodeGenFunction &CGF) override; 99 100 llvm::Value * 101 GetVirtualBaseClassOffset(CodeGenFunction &CGF, llvm::Value *This, 102 const CXXRecordDecl *ClassDecl, 103 const CXXRecordDecl *BaseClassDecl) override; 104 105 llvm::BasicBlock * 106 EmitCtorCompleteObjectHandler(CodeGenFunction &CGF, 107 const CXXRecordDecl *RD) override; 108 109 void initializeHiddenVirtualInheritanceMembers(CodeGenFunction &CGF, 110 const CXXRecordDecl *RD) override; 111 112 void EmitCXXConstructors(const CXXConstructorDecl *D) override; 113 114 // Background on MSVC destructors 115 // ============================== 116 // 117 // Both Itanium and MSVC ABIs have destructor variants. The variant names 118 // roughly correspond in the following way: 119 // Itanium Microsoft 120 // Base -> no name, just ~Class 121 // Complete -> vbase destructor 122 // Deleting -> scalar deleting destructor 123 // vector deleting destructor 124 // 125 // The base and complete destructors are the same as in Itanium, although the 126 // complete destructor does not accept a VTT parameter when there are virtual 127 // bases. A separate mechanism involving vtordisps is used to ensure that 128 // virtual methods of destroyed subobjects are not called. 129 // 130 // The deleting destructors accept an i32 bitfield as a second parameter. Bit 131 // 1 indicates if the memory should be deleted. Bit 2 indicates if the this 132 // pointer points to an array. The scalar deleting destructor assumes that 133 // bit 2 is zero, and therefore does not contain a loop. 134 // 135 // For virtual destructors, only one entry is reserved in the vftable, and it 136 // always points to the vector deleting destructor. The vector deleting 137 // destructor is the most general, so it can be used to destroy objects in 138 // place, delete single heap objects, or delete arrays. 139 // 140 // A TU defining a non-inline destructor is only guaranteed to emit a base 141 // destructor, and all of the other variants are emitted on an as-needed basis 142 // in COMDATs. Because a non-base destructor can be emitted in a TU that 143 // lacks a definition for the destructor, non-base destructors must always 144 // delegate to or alias the base destructor. 145 146 void buildStructorSignature(const CXXMethodDecl *MD, StructorType T, 147 SmallVectorImpl<CanQualType> &ArgTys) override; 148 149 /// Non-base dtors should be emitted as delegating thunks in this ABI. 150 bool useThunkForDtorVariant(const CXXDestructorDecl *Dtor, 151 CXXDtorType DT) const override { 152 return DT != Dtor_Base; 153 } 154 155 void EmitCXXDestructors(const CXXDestructorDecl *D) override; 156 157 const CXXRecordDecl * 158 getThisArgumentTypeForMethod(const CXXMethodDecl *MD) override { 159 MD = MD->getCanonicalDecl(); 160 if (MD->isVirtual() && !isa<CXXDestructorDecl>(MD)) { 161 MicrosoftVTableContext::MethodVFTableLocation ML = 162 CGM.getMicrosoftVTableContext().getMethodVFTableLocation(MD); 163 // The vbases might be ordered differently in the final overrider object 164 // and the complete object, so the "this" argument may sometimes point to 165 // memory that has no particular type (e.g. past the complete object). 166 // In this case, we just use a generic pointer type. 167 // FIXME: might want to have a more precise type in the non-virtual 168 // multiple inheritance case. 169 if (ML.VBase || !ML.VFPtrOffset.isZero()) 170 return nullptr; 171 } 172 return MD->getParent(); 173 } 174 175 llvm::Value * 176 adjustThisArgumentForVirtualFunctionCall(CodeGenFunction &CGF, GlobalDecl GD, 177 llvm::Value *This, 178 bool VirtualCall) override; 179 180 void addImplicitStructorParams(CodeGenFunction &CGF, QualType &ResTy, 181 FunctionArgList &Params) override; 182 183 llvm::Value *adjustThisParameterInVirtualFunctionPrologue( 184 CodeGenFunction &CGF, GlobalDecl GD, llvm::Value *This) override; 185 186 void EmitInstanceFunctionProlog(CodeGenFunction &CGF) override; 187 188 unsigned addImplicitConstructorArgs(CodeGenFunction &CGF, 189 const CXXConstructorDecl *D, 190 CXXCtorType Type, bool ForVirtualBase, 191 bool Delegating, 192 CallArgList &Args) override; 193 194 void EmitDestructorCall(CodeGenFunction &CGF, const CXXDestructorDecl *DD, 195 CXXDtorType Type, bool ForVirtualBase, 196 bool Delegating, llvm::Value *This) override; 197 198 void emitVTableDefinitions(CodeGenVTables &CGVT, 199 const CXXRecordDecl *RD) override; 200 201 llvm::Value *getVTableAddressPointInStructor( 202 CodeGenFunction &CGF, const CXXRecordDecl *VTableClass, 203 BaseSubobject Base, const CXXRecordDecl *NearestVBase, 204 bool &NeedsVirtualOffset) override; 205 206 llvm::Constant * 207 getVTableAddressPointForConstExpr(BaseSubobject Base, 208 const CXXRecordDecl *VTableClass) override; 209 210 llvm::GlobalVariable *getAddrOfVTable(const CXXRecordDecl *RD, 211 CharUnits VPtrOffset) override; 212 213 llvm::Value *getVirtualFunctionPointer(CodeGenFunction &CGF, GlobalDecl GD, 214 llvm::Value *This, 215 llvm::Type *Ty) override; 216 217 llvm::Value *EmitVirtualDestructorCall(CodeGenFunction &CGF, 218 const CXXDestructorDecl *Dtor, 219 CXXDtorType DtorType, 220 llvm::Value *This, 221 const CXXMemberCallExpr *CE) override; 222 223 void adjustCallArgsForDestructorThunk(CodeGenFunction &CGF, GlobalDecl GD, 224 CallArgList &CallArgs) override { 225 assert(GD.getDtorType() == Dtor_Deleting && 226 "Only deleting destructor thunks are available in this ABI"); 227 CallArgs.add(RValue::get(getStructorImplicitParamValue(CGF)), 228 CGM.getContext().IntTy); 229 } 230 231 void emitVirtualInheritanceTables(const CXXRecordDecl *RD) override; 232 233 llvm::GlobalVariable * 234 getAddrOfVBTable(const VPtrInfo &VBT, const CXXRecordDecl *RD, 235 llvm::GlobalVariable::LinkageTypes Linkage); 236 237 void emitVBTableDefinition(const VPtrInfo &VBT, const CXXRecordDecl *RD, 238 llvm::GlobalVariable *GV) const; 239 240 void setThunkLinkage(llvm::Function *Thunk, bool ForVTable, 241 GlobalDecl GD, bool ReturnAdjustment) override { 242 // Never dllimport/dllexport thunks. 243 Thunk->setDLLStorageClass(llvm::GlobalValue::DefaultStorageClass); 244 245 GVALinkage Linkage = 246 getContext().GetGVALinkageForFunction(cast<FunctionDecl>(GD.getDecl())); 247 248 if (Linkage == GVA_Internal) 249 Thunk->setLinkage(llvm::GlobalValue::InternalLinkage); 250 else if (ReturnAdjustment) 251 Thunk->setLinkage(llvm::GlobalValue::WeakODRLinkage); 252 else 253 Thunk->setLinkage(llvm::GlobalValue::LinkOnceODRLinkage); 254 } 255 256 llvm::Value *performThisAdjustment(CodeGenFunction &CGF, llvm::Value *This, 257 const ThisAdjustment &TA) override; 258 259 llvm::Value *performReturnAdjustment(CodeGenFunction &CGF, llvm::Value *Ret, 260 const ReturnAdjustment &RA) override; 261 262 void EmitThreadLocalInitFuncs( 263 CodeGenModule &CGM, 264 ArrayRef<std::pair<const VarDecl *, llvm::GlobalVariable *>> 265 CXXThreadLocals, 266 ArrayRef<llvm::Function *> CXXThreadLocalInits, 267 ArrayRef<llvm::GlobalVariable *> CXXThreadLocalInitVars) override; 268 269 bool usesThreadWrapperFunction() const override { return false; } 270 LValue EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF, const VarDecl *VD, 271 QualType LValType) override; 272 273 void EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D, 274 llvm::GlobalVariable *DeclPtr, 275 bool PerformInit) override; 276 void registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D, 277 llvm::Constant *Dtor, llvm::Constant *Addr) override; 278 279 // ==== Notes on array cookies ========= 280 // 281 // MSVC seems to only use cookies when the class has a destructor; a 282 // two-argument usual array deallocation function isn't sufficient. 283 // 284 // For example, this code prints "100" and "1": 285 // struct A { 286 // char x; 287 // void *operator new[](size_t sz) { 288 // printf("%u\n", sz); 289 // return malloc(sz); 290 // } 291 // void operator delete[](void *p, size_t sz) { 292 // printf("%u\n", sz); 293 // free(p); 294 // } 295 // }; 296 // int main() { 297 // A *p = new A[100]; 298 // delete[] p; 299 // } 300 // Whereas it prints "104" and "104" if you give A a destructor. 301 302 bool requiresArrayCookie(const CXXDeleteExpr *expr, 303 QualType elementType) override; 304 bool requiresArrayCookie(const CXXNewExpr *expr) override; 305 CharUnits getArrayCookieSizeImpl(QualType type) override; 306 llvm::Value *InitializeArrayCookie(CodeGenFunction &CGF, 307 llvm::Value *NewPtr, 308 llvm::Value *NumElements, 309 const CXXNewExpr *expr, 310 QualType ElementType) override; 311 llvm::Value *readArrayCookieImpl(CodeGenFunction &CGF, 312 llvm::Value *allocPtr, 313 CharUnits cookieSize) override; 314 315 friend struct MSRTTIBuilder; 316 317 bool isImageRelative() const { 318 return CGM.getTarget().getPointerWidth(/*AddressSpace=*/0) == 64; 319 } 320 321 // 5 routines for constructing the llvm types for MS RTTI structs. 322 llvm::StructType *getTypeDescriptorType(StringRef TypeInfoString) { 323 llvm::SmallString<32> TDTypeName("rtti.TypeDescriptor"); 324 TDTypeName += llvm::utostr(TypeInfoString.size()); 325 llvm::StructType *&TypeDescriptorType = 326 TypeDescriptorTypeMap[TypeInfoString.size()]; 327 if (TypeDescriptorType) 328 return TypeDescriptorType; 329 llvm::Type *FieldTypes[] = { 330 CGM.Int8PtrPtrTy, 331 CGM.Int8PtrTy, 332 llvm::ArrayType::get(CGM.Int8Ty, TypeInfoString.size() + 1)}; 333 TypeDescriptorType = 334 llvm::StructType::create(CGM.getLLVMContext(), FieldTypes, TDTypeName); 335 return TypeDescriptorType; 336 } 337 338 llvm::Type *getImageRelativeType(llvm::Type *PtrType) { 339 if (!isImageRelative()) 340 return PtrType; 341 return CGM.IntTy; 342 } 343 344 llvm::StructType *getBaseClassDescriptorType() { 345 if (BaseClassDescriptorType) 346 return BaseClassDescriptorType; 347 llvm::Type *FieldTypes[] = { 348 getImageRelativeType(CGM.Int8PtrTy), 349 CGM.IntTy, 350 CGM.IntTy, 351 CGM.IntTy, 352 CGM.IntTy, 353 CGM.IntTy, 354 getImageRelativeType(getClassHierarchyDescriptorType()->getPointerTo()), 355 }; 356 BaseClassDescriptorType = llvm::StructType::create( 357 CGM.getLLVMContext(), FieldTypes, "rtti.BaseClassDescriptor"); 358 return BaseClassDescriptorType; 359 } 360 361 llvm::StructType *getClassHierarchyDescriptorType() { 362 if (ClassHierarchyDescriptorType) 363 return ClassHierarchyDescriptorType; 364 // Forward-declare RTTIClassHierarchyDescriptor to break a cycle. 365 ClassHierarchyDescriptorType = llvm::StructType::create( 366 CGM.getLLVMContext(), "rtti.ClassHierarchyDescriptor"); 367 llvm::Type *FieldTypes[] = { 368 CGM.IntTy, 369 CGM.IntTy, 370 CGM.IntTy, 371 getImageRelativeType( 372 getBaseClassDescriptorType()->getPointerTo()->getPointerTo()), 373 }; 374 ClassHierarchyDescriptorType->setBody(FieldTypes); 375 return ClassHierarchyDescriptorType; 376 } 377 378 llvm::StructType *getCompleteObjectLocatorType() { 379 if (CompleteObjectLocatorType) 380 return CompleteObjectLocatorType; 381 CompleteObjectLocatorType = llvm::StructType::create( 382 CGM.getLLVMContext(), "rtti.CompleteObjectLocator"); 383 llvm::Type *FieldTypes[] = { 384 CGM.IntTy, 385 CGM.IntTy, 386 CGM.IntTy, 387 getImageRelativeType(CGM.Int8PtrTy), 388 getImageRelativeType(getClassHierarchyDescriptorType()->getPointerTo()), 389 getImageRelativeType(CompleteObjectLocatorType), 390 }; 391 llvm::ArrayRef<llvm::Type *> FieldTypesRef(FieldTypes); 392 if (!isImageRelative()) 393 FieldTypesRef = FieldTypesRef.drop_back(); 394 CompleteObjectLocatorType->setBody(FieldTypesRef); 395 return CompleteObjectLocatorType; 396 } 397 398 llvm::GlobalVariable *getImageBase() { 399 StringRef Name = "__ImageBase"; 400 if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(Name)) 401 return GV; 402 403 return new llvm::GlobalVariable(CGM.getModule(), CGM.Int8Ty, 404 /*isConstant=*/true, 405 llvm::GlobalValue::ExternalLinkage, 406 /*Initializer=*/nullptr, Name); 407 } 408 409 llvm::Constant *getImageRelativeConstant(llvm::Constant *PtrVal) { 410 if (!isImageRelative()) 411 return PtrVal; 412 413 llvm::Constant *ImageBaseAsInt = 414 llvm::ConstantExpr::getPtrToInt(getImageBase(), CGM.IntPtrTy); 415 llvm::Constant *PtrValAsInt = 416 llvm::ConstantExpr::getPtrToInt(PtrVal, CGM.IntPtrTy); 417 llvm::Constant *Diff = 418 llvm::ConstantExpr::getSub(PtrValAsInt, ImageBaseAsInt, 419 /*HasNUW=*/true, /*HasNSW=*/true); 420 return llvm::ConstantExpr::getTrunc(Diff, CGM.IntTy); 421 } 422 423private: 424 MicrosoftMangleContext &getMangleContext() { 425 return cast<MicrosoftMangleContext>(CodeGen::CGCXXABI::getMangleContext()); 426 } 427 428 llvm::Constant *getZeroInt() { 429 return llvm::ConstantInt::get(CGM.IntTy, 0); 430 } 431 432 llvm::Constant *getAllOnesInt() { 433 return llvm::Constant::getAllOnesValue(CGM.IntTy); 434 } 435 436 llvm::Constant *getConstantOrZeroInt(llvm::Constant *C) { 437 return C ? C : getZeroInt(); 438 } 439 440 llvm::Value *getValueOrZeroInt(llvm::Value *C) { 441 return C ? C : getZeroInt(); 442 } 443 444 CharUnits getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD); 445 446 void 447 GetNullMemberPointerFields(const MemberPointerType *MPT, 448 llvm::SmallVectorImpl<llvm::Constant *> &fields); 449 450 /// \brief Shared code for virtual base adjustment. Returns the offset from 451 /// the vbptr to the virtual base. Optionally returns the address of the 452 /// vbptr itself. 453 llvm::Value *GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF, 454 llvm::Value *Base, 455 llvm::Value *VBPtrOffset, 456 llvm::Value *VBTableOffset, 457 llvm::Value **VBPtr = nullptr); 458 459 llvm::Value *GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF, 460 llvm::Value *Base, 461 int32_t VBPtrOffset, 462 int32_t VBTableOffset, 463 llvm::Value **VBPtr = nullptr) { 464 assert(VBTableOffset % 4 == 0 && "should be byte offset into table of i32s"); 465 llvm::Value *VBPOffset = llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset), 466 *VBTOffset = llvm::ConstantInt::get(CGM.IntTy, VBTableOffset); 467 return GetVBaseOffsetFromVBPtr(CGF, Base, VBPOffset, VBTOffset, VBPtr); 468 } 469 470 /// \brief Performs a full virtual base adjustment. Used to dereference 471 /// pointers to members of virtual bases. 472 llvm::Value *AdjustVirtualBase(CodeGenFunction &CGF, const Expr *E, 473 const CXXRecordDecl *RD, llvm::Value *Base, 474 llvm::Value *VirtualBaseAdjustmentOffset, 475 llvm::Value *VBPtrOffset /* optional */); 476 477 /// \brief Emits a full member pointer with the fields common to data and 478 /// function member pointers. 479 llvm::Constant *EmitFullMemberPointer(llvm::Constant *FirstField, 480 bool IsMemberFunction, 481 const CXXRecordDecl *RD, 482 CharUnits NonVirtualBaseAdjustment); 483 484 llvm::Constant *BuildMemberPointer(const CXXRecordDecl *RD, 485 const CXXMethodDecl *MD, 486 CharUnits NonVirtualBaseAdjustment); 487 488 bool MemberPointerConstantIsNull(const MemberPointerType *MPT, 489 llvm::Constant *MP); 490 491 /// \brief - Initialize all vbptrs of 'this' with RD as the complete type. 492 void EmitVBPtrStores(CodeGenFunction &CGF, const CXXRecordDecl *RD); 493 494 /// \brief Caching wrapper around VBTableBuilder::enumerateVBTables(). 495 const VBTableGlobals &enumerateVBTables(const CXXRecordDecl *RD); 496 497 /// \brief Generate a thunk for calling a virtual member function MD. 498 llvm::Function *EmitVirtualMemPtrThunk( 499 const CXXMethodDecl *MD, 500 const MicrosoftVTableContext::MethodVFTableLocation &ML); 501 502public: 503 llvm::Type *ConvertMemberPointerType(const MemberPointerType *MPT) override; 504 505 bool isZeroInitializable(const MemberPointerType *MPT) override; 506 507 bool isMemberPointerConvertible(const MemberPointerType *MPT) const override { 508 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl(); 509 return RD->hasAttr<MSInheritanceAttr>(); 510 } 511 512 bool isTypeInfoCalculable(QualType Ty) const override { 513 if (!CGCXXABI::isTypeInfoCalculable(Ty)) 514 return false; 515 if (const auto *MPT = Ty->getAs<MemberPointerType>()) { 516 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl(); 517 if (!RD->hasAttr<MSInheritanceAttr>()) 518 return false; 519 } 520 return true; 521 } 522 523 llvm::Constant *EmitNullMemberPointer(const MemberPointerType *MPT) override; 524 525 llvm::Constant *EmitMemberDataPointer(const MemberPointerType *MPT, 526 CharUnits offset) override; 527 llvm::Constant *EmitMemberPointer(const CXXMethodDecl *MD) override; 528 llvm::Constant *EmitMemberPointer(const APValue &MP, QualType MPT) override; 529 530 llvm::Value *EmitMemberPointerComparison(CodeGenFunction &CGF, 531 llvm::Value *L, 532 llvm::Value *R, 533 const MemberPointerType *MPT, 534 bool Inequality) override; 535 536 llvm::Value *EmitMemberPointerIsNotNull(CodeGenFunction &CGF, 537 llvm::Value *MemPtr, 538 const MemberPointerType *MPT) override; 539 540 llvm::Value * 541 EmitMemberDataPointerAddress(CodeGenFunction &CGF, const Expr *E, 542 llvm::Value *Base, llvm::Value *MemPtr, 543 const MemberPointerType *MPT) override; 544 545 llvm::Value *EmitMemberPointerConversion(CodeGenFunction &CGF, 546 const CastExpr *E, 547 llvm::Value *Src) override; 548 549 llvm::Constant *EmitMemberPointerConversion(const CastExpr *E, 550 llvm::Constant *Src) override; 551 552 llvm::Value * 553 EmitLoadOfMemberFunctionPointer(CodeGenFunction &CGF, const Expr *E, 554 llvm::Value *&This, llvm::Value *MemPtr, 555 const MemberPointerType *MPT) override; 556 557 void emitCXXStructor(const CXXMethodDecl *MD, StructorType Type) override; 558 559private: 560 typedef std::pair<const CXXRecordDecl *, CharUnits> VFTableIdTy; 561 typedef llvm::DenseMap<VFTableIdTy, llvm::GlobalVariable *> VTablesMapTy; 562 typedef llvm::DenseMap<VFTableIdTy, llvm::GlobalValue *> VFTablesMapTy; 563 /// \brief All the vftables that have been referenced. 564 VFTablesMapTy VFTablesMap; 565 VTablesMapTy VTablesMap; 566 567 /// \brief This set holds the record decls we've deferred vtable emission for. 568 llvm::SmallPtrSet<const CXXRecordDecl *, 4> DeferredVFTables; 569 570 571 /// \brief All the vbtables which have been referenced. 572 llvm::DenseMap<const CXXRecordDecl *, VBTableGlobals> VBTablesMap; 573 574 /// Info on the global variable used to guard initialization of static locals. 575 /// The BitIndex field is only used for externally invisible declarations. 576 struct GuardInfo { 577 GuardInfo() : Guard(nullptr), BitIndex(0) {} 578 llvm::GlobalVariable *Guard; 579 unsigned BitIndex; 580 }; 581 582 /// Map from DeclContext to the current guard variable. We assume that the 583 /// AST is visited in source code order. 584 llvm::DenseMap<const DeclContext *, GuardInfo> GuardVariableMap; 585 586 llvm::DenseMap<size_t, llvm::StructType *> TypeDescriptorTypeMap; 587 llvm::StructType *BaseClassDescriptorType; 588 llvm::StructType *ClassHierarchyDescriptorType; 589 llvm::StructType *CompleteObjectLocatorType; 590}; 591 592} 593 594CGCXXABI::RecordArgABI 595MicrosoftCXXABI::getRecordArgABI(const CXXRecordDecl *RD) const { 596 switch (CGM.getTarget().getTriple().getArch()) { 597 default: 598 // FIXME: Implement for other architectures. 599 return RAA_Default; 600 601 case llvm::Triple::x86: 602 // All record arguments are passed in memory on x86. Decide whether to 603 // construct the object directly in argument memory, or to construct the 604 // argument elsewhere and copy the bytes during the call. 605 606 // If C++ prohibits us from making a copy, construct the arguments directly 607 // into argument memory. 608 if (!canCopyArgument(RD)) 609 return RAA_DirectInMemory; 610 611 // Otherwise, construct the argument into a temporary and copy the bytes 612 // into the outgoing argument memory. 613 return RAA_Default; 614 615 case llvm::Triple::x86_64: 616 // Win64 passes objects with non-trivial copy ctors indirectly. 617 if (RD->hasNonTrivialCopyConstructor()) 618 return RAA_Indirect; 619 620 // If an object has a destructor, we'd really like to pass it indirectly 621 // because it allows us to elide copies. Unfortunately, MSVC makes that 622 // impossible for small types, which it will pass in a single register or 623 // stack slot. Most objects with dtors are large-ish, so handle that early. 624 // We can't call out all large objects as being indirect because there are 625 // multiple x64 calling conventions and the C++ ABI code shouldn't dictate 626 // how we pass large POD types. 627 if (RD->hasNonTrivialDestructor() && 628 getContext().getTypeSize(RD->getTypeForDecl()) > 64) 629 return RAA_Indirect; 630 631 // We have a trivial copy constructor or no copy constructors, but we have 632 // to make sure it isn't deleted. 633 bool CopyDeleted = false; 634 for (const CXXConstructorDecl *CD : RD->ctors()) { 635 if (CD->isCopyConstructor()) { 636 assert(CD->isTrivial()); 637 // We had at least one undeleted trivial copy ctor. Return directly. 638 if (!CD->isDeleted()) 639 return RAA_Default; 640 CopyDeleted = true; 641 } 642 } 643 644 // The trivial copy constructor was deleted. Return indirectly. 645 if (CopyDeleted) 646 return RAA_Indirect; 647 648 // There were no copy ctors. Return in RAX. 649 return RAA_Default; 650 } 651 652 llvm_unreachable("invalid enum"); 653} 654 655void MicrosoftCXXABI::emitVirtualObjectDelete(CodeGenFunction &CGF, 656 const CXXDeleteExpr *DE, 657 llvm::Value *Ptr, 658 QualType ElementType, 659 const CXXDestructorDecl *Dtor) { 660 // FIXME: Provide a source location here even though there's no 661 // CXXMemberCallExpr for dtor call. 662 bool UseGlobalDelete = DE->isGlobalDelete(); 663 CXXDtorType DtorType = UseGlobalDelete ? Dtor_Complete : Dtor_Deleting; 664 llvm::Value *MDThis = 665 EmitVirtualDestructorCall(CGF, Dtor, DtorType, Ptr, /*CE=*/nullptr); 666 if (UseGlobalDelete) 667 CGF.EmitDeleteCall(DE->getOperatorDelete(), MDThis, ElementType); 668} 669 670static llvm::Function *getRethrowFn(CodeGenModule &CGM) { 671 // _CxxThrowException takes two pointer width arguments: a value and a context 672 // object which points to a TypeInfo object. 673 llvm::Type *ArgTypes[] = {CGM.Int8PtrTy, CGM.Int8PtrTy}; 674 llvm::FunctionType *FTy = 675 llvm::FunctionType::get(CGM.VoidTy, ArgTypes, false); 676 auto *Fn = cast<llvm::Function>( 677 CGM.CreateRuntimeFunction(FTy, "_CxxThrowException")); 678 // _CxxThrowException is stdcall on 32-bit x86 platforms. 679 if (CGM.getTarget().getTriple().getArch() == llvm::Triple::x86) 680 Fn->setCallingConv(llvm::CallingConv::X86_StdCall); 681 return Fn; 682} 683 684void MicrosoftCXXABI::emitRethrow(CodeGenFunction &CGF, bool isNoReturn) { 685 llvm::Value *Args[] = {llvm::ConstantPointerNull::get(CGM.Int8PtrTy), 686 llvm::ConstantPointerNull::get(CGM.Int8PtrTy)}; 687 auto *Fn = getRethrowFn(CGM); 688 if (isNoReturn) 689 CGF.EmitNoreturnRuntimeCallOrInvoke(Fn, Args); 690 else 691 CGF.EmitRuntimeCallOrInvoke(Fn, Args); 692} 693 694/// \brief Gets the offset to the virtual base that contains the vfptr for 695/// MS-ABI polymorphic types. 696static llvm::Value *getPolymorphicOffset(CodeGenFunction &CGF, 697 const CXXRecordDecl *RD, 698 llvm::Value *Value) { 699 const ASTContext &Context = RD->getASTContext(); 700 for (const CXXBaseSpecifier &Base : RD->vbases()) 701 if (Context.getASTRecordLayout(Base.getType()->getAsCXXRecordDecl()) 702 .hasExtendableVFPtr()) 703 return CGF.CGM.getCXXABI().GetVirtualBaseClassOffset( 704 CGF, Value, RD, Base.getType()->getAsCXXRecordDecl()); 705 llvm_unreachable("One of our vbases should be polymorphic."); 706} 707 708static std::pair<llvm::Value *, llvm::Value *> 709performBaseAdjustment(CodeGenFunction &CGF, llvm::Value *Value, 710 QualType SrcRecordTy) { 711 Value = CGF.Builder.CreateBitCast(Value, CGF.Int8PtrTy); 712 const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl(); 713 714 if (CGF.getContext().getASTRecordLayout(SrcDecl).hasExtendableVFPtr()) 715 return std::make_pair(Value, llvm::ConstantInt::get(CGF.Int32Ty, 0)); 716 717 // Perform a base adjustment. 718 llvm::Value *Offset = getPolymorphicOffset(CGF, SrcDecl, Value); 719 Value = CGF.Builder.CreateInBoundsGEP(Value, Offset); 720 Offset = CGF.Builder.CreateTrunc(Offset, CGF.Int32Ty); 721 return std::make_pair(Value, Offset); 722} 723 724bool MicrosoftCXXABI::shouldTypeidBeNullChecked(bool IsDeref, 725 QualType SrcRecordTy) { 726 const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl(); 727 return IsDeref && 728 !CGM.getContext().getASTRecordLayout(SrcDecl).hasExtendableVFPtr(); 729} 730 731static llvm::CallSite emitRTtypeidCall(CodeGenFunction &CGF, 732 llvm::Value *Argument) { 733 llvm::Type *ArgTypes[] = {CGF.Int8PtrTy}; 734 llvm::FunctionType *FTy = 735 llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false); 736 llvm::Value *Args[] = {Argument}; 737 llvm::Constant *Fn = CGF.CGM.CreateRuntimeFunction(FTy, "__RTtypeid"); 738 return CGF.EmitRuntimeCallOrInvoke(Fn, Args); 739} 740 741void MicrosoftCXXABI::EmitBadTypeidCall(CodeGenFunction &CGF) { 742 llvm::CallSite Call = 743 emitRTtypeidCall(CGF, llvm::Constant::getNullValue(CGM.VoidPtrTy)); 744 Call.setDoesNotReturn(); 745 CGF.Builder.CreateUnreachable(); 746} 747 748llvm::Value *MicrosoftCXXABI::EmitTypeid(CodeGenFunction &CGF, 749 QualType SrcRecordTy, 750 llvm::Value *ThisPtr, 751 llvm::Type *StdTypeInfoPtrTy) { 752 llvm::Value *Offset; 753 std::tie(ThisPtr, Offset) = performBaseAdjustment(CGF, ThisPtr, SrcRecordTy); 754 return CGF.Builder.CreateBitCast( 755 emitRTtypeidCall(CGF, ThisPtr).getInstruction(), StdTypeInfoPtrTy); 756} 757 758bool MicrosoftCXXABI::shouldDynamicCastCallBeNullChecked(bool SrcIsPtr, 759 QualType SrcRecordTy) { 760 const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl(); 761 return SrcIsPtr && 762 !CGM.getContext().getASTRecordLayout(SrcDecl).hasExtendableVFPtr(); 763} 764 765llvm::Value *MicrosoftCXXABI::EmitDynamicCastCall( 766 CodeGenFunction &CGF, llvm::Value *Value, QualType SrcRecordTy, 767 QualType DestTy, QualType DestRecordTy, llvm::BasicBlock *CastEnd) { 768 llvm::Type *DestLTy = CGF.ConvertType(DestTy); 769 770 llvm::Value *SrcRTTI = 771 CGF.CGM.GetAddrOfRTTIDescriptor(SrcRecordTy.getUnqualifiedType()); 772 llvm::Value *DestRTTI = 773 CGF.CGM.GetAddrOfRTTIDescriptor(DestRecordTy.getUnqualifiedType()); 774 775 llvm::Value *Offset; 776 std::tie(Value, Offset) = performBaseAdjustment(CGF, Value, SrcRecordTy); 777 778 // PVOID __RTDynamicCast( 779 // PVOID inptr, 780 // LONG VfDelta, 781 // PVOID SrcType, 782 // PVOID TargetType, 783 // BOOL isReference) 784 llvm::Type *ArgTypes[] = {CGF.Int8PtrTy, CGF.Int32Ty, CGF.Int8PtrTy, 785 CGF.Int8PtrTy, CGF.Int32Ty}; 786 llvm::Constant *Function = CGF.CGM.CreateRuntimeFunction( 787 llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false), 788 "__RTDynamicCast"); 789 llvm::Value *Args[] = { 790 Value, Offset, SrcRTTI, DestRTTI, 791 llvm::ConstantInt::get(CGF.Int32Ty, DestTy->isReferenceType())}; 792 Value = CGF.EmitRuntimeCallOrInvoke(Function, Args).getInstruction(); 793 return CGF.Builder.CreateBitCast(Value, DestLTy); 794} 795 796llvm::Value * 797MicrosoftCXXABI::EmitDynamicCastToVoid(CodeGenFunction &CGF, llvm::Value *Value, 798 QualType SrcRecordTy, 799 QualType DestTy) { 800 llvm::Value *Offset; 801 std::tie(Value, Offset) = performBaseAdjustment(CGF, Value, SrcRecordTy); 802 803 // PVOID __RTCastToVoid( 804 // PVOID inptr) 805 llvm::Type *ArgTypes[] = {CGF.Int8PtrTy}; 806 llvm::Constant *Function = CGF.CGM.CreateRuntimeFunction( 807 llvm::FunctionType::get(CGF.Int8PtrTy, ArgTypes, false), 808 "__RTCastToVoid"); 809 llvm::Value *Args[] = {Value}; 810 return CGF.EmitRuntimeCall(Function, Args); 811} 812 813bool MicrosoftCXXABI::EmitBadCastCall(CodeGenFunction &CGF) { 814 return false; 815} 816 817llvm::Value *MicrosoftCXXABI::GetVirtualBaseClassOffset( 818 CodeGenFunction &CGF, llvm::Value *This, const CXXRecordDecl *ClassDecl, 819 const CXXRecordDecl *BaseClassDecl) { 820 int64_t VBPtrChars = 821 getContext().getASTRecordLayout(ClassDecl).getVBPtrOffset().getQuantity(); 822 llvm::Value *VBPtrOffset = llvm::ConstantInt::get(CGM.PtrDiffTy, VBPtrChars); 823 CharUnits IntSize = getContext().getTypeSizeInChars(getContext().IntTy); 824 CharUnits VBTableChars = 825 IntSize * 826 CGM.getMicrosoftVTableContext().getVBTableIndex(ClassDecl, BaseClassDecl); 827 llvm::Value *VBTableOffset = 828 llvm::ConstantInt::get(CGM.IntTy, VBTableChars.getQuantity()); 829 830 llvm::Value *VBPtrToNewBase = 831 GetVBaseOffsetFromVBPtr(CGF, This, VBPtrOffset, VBTableOffset); 832 VBPtrToNewBase = 833 CGF.Builder.CreateSExtOrBitCast(VBPtrToNewBase, CGM.PtrDiffTy); 834 return CGF.Builder.CreateNSWAdd(VBPtrOffset, VBPtrToNewBase); 835} 836 837bool MicrosoftCXXABI::HasThisReturn(GlobalDecl GD) const { 838 return isa<CXXConstructorDecl>(GD.getDecl()); 839} 840 841static bool isDeletingDtor(GlobalDecl GD) { 842 return isa<CXXDestructorDecl>(GD.getDecl()) && 843 GD.getDtorType() == Dtor_Deleting; 844} 845 846bool MicrosoftCXXABI::hasMostDerivedReturn(GlobalDecl GD) const { 847 return isDeletingDtor(GD); 848} 849 850bool MicrosoftCXXABI::classifyReturnType(CGFunctionInfo &FI) const { 851 const CXXRecordDecl *RD = FI.getReturnType()->getAsCXXRecordDecl(); 852 if (!RD) 853 return false; 854 855 if (FI.isInstanceMethod()) { 856 // If it's an instance method, aggregates are always returned indirectly via 857 // the second parameter. 858 FI.getReturnInfo() = ABIArgInfo::getIndirect(0, /*ByVal=*/false); 859 FI.getReturnInfo().setSRetAfterThis(FI.isInstanceMethod()); 860 return true; 861 } else if (!RD->isPOD()) { 862 // If it's a free function, non-POD types are returned indirectly. 863 FI.getReturnInfo() = ABIArgInfo::getIndirect(0, /*ByVal=*/false); 864 return true; 865 } 866 867 // Otherwise, use the C ABI rules. 868 return false; 869} 870 871llvm::BasicBlock * 872MicrosoftCXXABI::EmitCtorCompleteObjectHandler(CodeGenFunction &CGF, 873 const CXXRecordDecl *RD) { 874 llvm::Value *IsMostDerivedClass = getStructorImplicitParamValue(CGF); 875 assert(IsMostDerivedClass && 876 "ctor for a class with virtual bases must have an implicit parameter"); 877 llvm::Value *IsCompleteObject = 878 CGF.Builder.CreateIsNotNull(IsMostDerivedClass, "is_complete_object"); 879 880 llvm::BasicBlock *CallVbaseCtorsBB = CGF.createBasicBlock("ctor.init_vbases"); 881 llvm::BasicBlock *SkipVbaseCtorsBB = CGF.createBasicBlock("ctor.skip_vbases"); 882 CGF.Builder.CreateCondBr(IsCompleteObject, 883 CallVbaseCtorsBB, SkipVbaseCtorsBB); 884 885 CGF.EmitBlock(CallVbaseCtorsBB); 886 887 // Fill in the vbtable pointers here. 888 EmitVBPtrStores(CGF, RD); 889 890 // CGF will put the base ctor calls in this basic block for us later. 891 892 return SkipVbaseCtorsBB; 893} 894 895void MicrosoftCXXABI::initializeHiddenVirtualInheritanceMembers( 896 CodeGenFunction &CGF, const CXXRecordDecl *RD) { 897 // In most cases, an override for a vbase virtual method can adjust 898 // the "this" parameter by applying a constant offset. 899 // However, this is not enough while a constructor or a destructor of some 900 // class X is being executed if all the following conditions are met: 901 // - X has virtual bases, (1) 902 // - X overrides a virtual method M of a vbase Y, (2) 903 // - X itself is a vbase of the most derived class. 904 // 905 // If (1) and (2) are true, the vtorDisp for vbase Y is a hidden member of X 906 // which holds the extra amount of "this" adjustment we must do when we use 907 // the X vftables (i.e. during X ctor or dtor). 908 // Outside the ctors and dtors, the values of vtorDisps are zero. 909 910 const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD); 911 typedef ASTRecordLayout::VBaseOffsetsMapTy VBOffsets; 912 const VBOffsets &VBaseMap = Layout.getVBaseOffsetsMap(); 913 CGBuilderTy &Builder = CGF.Builder; 914 915 unsigned AS = 916 cast<llvm::PointerType>(getThisValue(CGF)->getType())->getAddressSpace(); 917 llvm::Value *Int8This = nullptr; // Initialize lazily. 918 919 for (VBOffsets::const_iterator I = VBaseMap.begin(), E = VBaseMap.end(); 920 I != E; ++I) { 921 if (!I->second.hasVtorDisp()) 922 continue; 923 924 llvm::Value *VBaseOffset = 925 GetVirtualBaseClassOffset(CGF, getThisValue(CGF), RD, I->first); 926 // FIXME: it doesn't look right that we SExt in GetVirtualBaseClassOffset() 927 // just to Trunc back immediately. 928 VBaseOffset = Builder.CreateTruncOrBitCast(VBaseOffset, CGF.Int32Ty); 929 uint64_t ConstantVBaseOffset = 930 Layout.getVBaseClassOffset(I->first).getQuantity(); 931 932 // vtorDisp_for_vbase = vbptr[vbase_idx] - offsetof(RD, vbase). 933 llvm::Value *VtorDispValue = Builder.CreateSub( 934 VBaseOffset, llvm::ConstantInt::get(CGM.Int32Ty, ConstantVBaseOffset), 935 "vtordisp.value"); 936 937 if (!Int8This) 938 Int8This = Builder.CreateBitCast(getThisValue(CGF), 939 CGF.Int8Ty->getPointerTo(AS)); 940 llvm::Value *VtorDispPtr = Builder.CreateInBoundsGEP(Int8This, VBaseOffset); 941 // vtorDisp is always the 32-bits before the vbase in the class layout. 942 VtorDispPtr = Builder.CreateConstGEP1_32(VtorDispPtr, -4); 943 VtorDispPtr = Builder.CreateBitCast( 944 VtorDispPtr, CGF.Int32Ty->getPointerTo(AS), "vtordisp.ptr"); 945 946 Builder.CreateStore(VtorDispValue, VtorDispPtr); 947 } 948} 949 950void MicrosoftCXXABI::EmitCXXConstructors(const CXXConstructorDecl *D) { 951 // There's only one constructor type in this ABI. 952 CGM.EmitGlobal(GlobalDecl(D, Ctor_Complete)); 953} 954 955void MicrosoftCXXABI::EmitVBPtrStores(CodeGenFunction &CGF, 956 const CXXRecordDecl *RD) { 957 llvm::Value *ThisInt8Ptr = 958 CGF.Builder.CreateBitCast(getThisValue(CGF), CGM.Int8PtrTy, "this.int8"); 959 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD); 960 961 const VBTableGlobals &VBGlobals = enumerateVBTables(RD); 962 for (unsigned I = 0, E = VBGlobals.VBTables->size(); I != E; ++I) { 963 const VPtrInfo *VBT = (*VBGlobals.VBTables)[I]; 964 llvm::GlobalVariable *GV = VBGlobals.Globals[I]; 965 const ASTRecordLayout &SubobjectLayout = 966 CGM.getContext().getASTRecordLayout(VBT->BaseWithVPtr); 967 CharUnits Offs = VBT->NonVirtualOffset; 968 Offs += SubobjectLayout.getVBPtrOffset(); 969 if (VBT->getVBaseWithVPtr()) 970 Offs += Layout.getVBaseClassOffset(VBT->getVBaseWithVPtr()); 971 llvm::Value *VBPtr = 972 CGF.Builder.CreateConstInBoundsGEP1_64(ThisInt8Ptr, Offs.getQuantity()); 973 llvm::Value *GVPtr = CGF.Builder.CreateConstInBoundsGEP2_32(GV, 0, 0); 974 VBPtr = CGF.Builder.CreateBitCast(VBPtr, GVPtr->getType()->getPointerTo(0), 975 "vbptr." + VBT->ReusingBase->getName()); 976 CGF.Builder.CreateStore(GVPtr, VBPtr); 977 } 978} 979 980void 981MicrosoftCXXABI::buildStructorSignature(const CXXMethodDecl *MD, StructorType T, 982 SmallVectorImpl<CanQualType> &ArgTys) { 983 // TODO: 'for base' flag 984 if (T == StructorType::Deleting) { 985 // The scalar deleting destructor takes an implicit int parameter. 986 ArgTys.push_back(CGM.getContext().IntTy); 987 } 988 auto *CD = dyn_cast<CXXConstructorDecl>(MD); 989 if (!CD) 990 return; 991 992 // All parameters are already in place except is_most_derived, which goes 993 // after 'this' if it's variadic and last if it's not. 994 995 const CXXRecordDecl *Class = CD->getParent(); 996 const FunctionProtoType *FPT = CD->getType()->castAs<FunctionProtoType>(); 997 if (Class->getNumVBases()) { 998 if (FPT->isVariadic()) 999 ArgTys.insert(ArgTys.begin() + 1, CGM.getContext().IntTy); 1000 else 1001 ArgTys.push_back(CGM.getContext().IntTy); 1002 } 1003} 1004 1005void MicrosoftCXXABI::EmitCXXDestructors(const CXXDestructorDecl *D) { 1006 // The TU defining a dtor is only guaranteed to emit a base destructor. All 1007 // other destructor variants are delegating thunks. 1008 CGM.EmitGlobal(GlobalDecl(D, Dtor_Base)); 1009} 1010 1011CharUnits 1012MicrosoftCXXABI::getVirtualFunctionPrologueThisAdjustment(GlobalDecl GD) { 1013 GD = GD.getCanonicalDecl(); 1014 const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); 1015 1016 GlobalDecl LookupGD = GD; 1017 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) { 1018 // Complete destructors take a pointer to the complete object as a 1019 // parameter, thus don't need this adjustment. 1020 if (GD.getDtorType() == Dtor_Complete) 1021 return CharUnits(); 1022 1023 // There's no Dtor_Base in vftable but it shares the this adjustment with 1024 // the deleting one, so look it up instead. 1025 LookupGD = GlobalDecl(DD, Dtor_Deleting); 1026 } 1027 1028 MicrosoftVTableContext::MethodVFTableLocation ML = 1029 CGM.getMicrosoftVTableContext().getMethodVFTableLocation(LookupGD); 1030 CharUnits Adjustment = ML.VFPtrOffset; 1031 1032 // Normal virtual instance methods need to adjust from the vfptr that first 1033 // defined the virtual method to the virtual base subobject, but destructors 1034 // do not. The vector deleting destructor thunk applies this adjustment for 1035 // us if necessary. 1036 if (isa<CXXDestructorDecl>(MD)) 1037 Adjustment = CharUnits::Zero(); 1038 1039 if (ML.VBase) { 1040 const ASTRecordLayout &DerivedLayout = 1041 CGM.getContext().getASTRecordLayout(MD->getParent()); 1042 Adjustment += DerivedLayout.getVBaseClassOffset(ML.VBase); 1043 } 1044 1045 return Adjustment; 1046} 1047 1048llvm::Value *MicrosoftCXXABI::adjustThisArgumentForVirtualFunctionCall( 1049 CodeGenFunction &CGF, GlobalDecl GD, llvm::Value *This, bool VirtualCall) { 1050 if (!VirtualCall) { 1051 // If the call of a virtual function is not virtual, we just have to 1052 // compensate for the adjustment the virtual function does in its prologue. 1053 CharUnits Adjustment = getVirtualFunctionPrologueThisAdjustment(GD); 1054 if (Adjustment.isZero()) 1055 return This; 1056 1057 unsigned AS = cast<llvm::PointerType>(This->getType())->getAddressSpace(); 1058 llvm::Type *charPtrTy = CGF.Int8Ty->getPointerTo(AS); 1059 This = CGF.Builder.CreateBitCast(This, charPtrTy); 1060 assert(Adjustment.isPositive()); 1061 return CGF.Builder.CreateConstGEP1_32(This, Adjustment.getQuantity()); 1062 } 1063 1064 GD = GD.getCanonicalDecl(); 1065 const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); 1066 1067 GlobalDecl LookupGD = GD; 1068 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) { 1069 // Complete dtors take a pointer to the complete object, 1070 // thus don't need adjustment. 1071 if (GD.getDtorType() == Dtor_Complete) 1072 return This; 1073 1074 // There's only Dtor_Deleting in vftable but it shares the this adjustment 1075 // with the base one, so look up the deleting one instead. 1076 LookupGD = GlobalDecl(DD, Dtor_Deleting); 1077 } 1078 MicrosoftVTableContext::MethodVFTableLocation ML = 1079 CGM.getMicrosoftVTableContext().getMethodVFTableLocation(LookupGD); 1080 1081 unsigned AS = cast<llvm::PointerType>(This->getType())->getAddressSpace(); 1082 llvm::Type *charPtrTy = CGF.Int8Ty->getPointerTo(AS); 1083 CharUnits StaticOffset = ML.VFPtrOffset; 1084 1085 // Base destructors expect 'this' to point to the beginning of the base 1086 // subobject, not the first vfptr that happens to contain the virtual dtor. 1087 // However, we still need to apply the virtual base adjustment. 1088 if (isa<CXXDestructorDecl>(MD) && GD.getDtorType() == Dtor_Base) 1089 StaticOffset = CharUnits::Zero(); 1090 1091 if (ML.VBase) { 1092 This = CGF.Builder.CreateBitCast(This, charPtrTy); 1093 llvm::Value *VBaseOffset = 1094 GetVirtualBaseClassOffset(CGF, This, MD->getParent(), ML.VBase); 1095 This = CGF.Builder.CreateInBoundsGEP(This, VBaseOffset); 1096 } 1097 if (!StaticOffset.isZero()) { 1098 assert(StaticOffset.isPositive()); 1099 This = CGF.Builder.CreateBitCast(This, charPtrTy); 1100 if (ML.VBase) { 1101 // Non-virtual adjustment might result in a pointer outside the allocated 1102 // object, e.g. if the final overrider class is laid out after the virtual 1103 // base that declares a method in the most derived class. 1104 // FIXME: Update the code that emits this adjustment in thunks prologues. 1105 This = CGF.Builder.CreateConstGEP1_32(This, StaticOffset.getQuantity()); 1106 } else { 1107 This = CGF.Builder.CreateConstInBoundsGEP1_32(This, 1108 StaticOffset.getQuantity()); 1109 } 1110 } 1111 return This; 1112} 1113 1114void MicrosoftCXXABI::addImplicitStructorParams(CodeGenFunction &CGF, 1115 QualType &ResTy, 1116 FunctionArgList &Params) { 1117 ASTContext &Context = getContext(); 1118 const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl()); 1119 assert(isa<CXXConstructorDecl>(MD) || isa<CXXDestructorDecl>(MD)); 1120 if (isa<CXXConstructorDecl>(MD) && MD->getParent()->getNumVBases()) { 1121 ImplicitParamDecl *IsMostDerived 1122 = ImplicitParamDecl::Create(Context, nullptr, 1123 CGF.CurGD.getDecl()->getLocation(), 1124 &Context.Idents.get("is_most_derived"), 1125 Context.IntTy); 1126 // The 'most_derived' parameter goes second if the ctor is variadic and last 1127 // if it's not. Dtors can't be variadic. 1128 const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>(); 1129 if (FPT->isVariadic()) 1130 Params.insert(Params.begin() + 1, IsMostDerived); 1131 else 1132 Params.push_back(IsMostDerived); 1133 getStructorImplicitParamDecl(CGF) = IsMostDerived; 1134 } else if (isDeletingDtor(CGF.CurGD)) { 1135 ImplicitParamDecl *ShouldDelete 1136 = ImplicitParamDecl::Create(Context, nullptr, 1137 CGF.CurGD.getDecl()->getLocation(), 1138 &Context.Idents.get("should_call_delete"), 1139 Context.IntTy); 1140 Params.push_back(ShouldDelete); 1141 getStructorImplicitParamDecl(CGF) = ShouldDelete; 1142 } 1143} 1144 1145llvm::Value *MicrosoftCXXABI::adjustThisParameterInVirtualFunctionPrologue( 1146 CodeGenFunction &CGF, GlobalDecl GD, llvm::Value *This) { 1147 // In this ABI, every virtual function takes a pointer to one of the 1148 // subobjects that first defines it as the 'this' parameter, rather than a 1149 // pointer to the final overrider subobject. Thus, we need to adjust it back 1150 // to the final overrider subobject before use. 1151 // See comments in the MicrosoftVFTableContext implementation for the details. 1152 CharUnits Adjustment = getVirtualFunctionPrologueThisAdjustment(GD); 1153 if (Adjustment.isZero()) 1154 return This; 1155 1156 unsigned AS = cast<llvm::PointerType>(This->getType())->getAddressSpace(); 1157 llvm::Type *charPtrTy = CGF.Int8Ty->getPointerTo(AS), 1158 *thisTy = This->getType(); 1159 1160 This = CGF.Builder.CreateBitCast(This, charPtrTy); 1161 assert(Adjustment.isPositive()); 1162 This = 1163 CGF.Builder.CreateConstInBoundsGEP1_32(This, -Adjustment.getQuantity()); 1164 return CGF.Builder.CreateBitCast(This, thisTy); 1165} 1166 1167void MicrosoftCXXABI::EmitInstanceFunctionProlog(CodeGenFunction &CGF) { 1168 EmitThisParam(CGF); 1169 1170 /// If this is a function that the ABI specifies returns 'this', initialize 1171 /// the return slot to 'this' at the start of the function. 1172 /// 1173 /// Unlike the setting of return types, this is done within the ABI 1174 /// implementation instead of by clients of CGCXXABI because: 1175 /// 1) getThisValue is currently protected 1176 /// 2) in theory, an ABI could implement 'this' returns some other way; 1177 /// HasThisReturn only specifies a contract, not the implementation 1178 if (HasThisReturn(CGF.CurGD)) 1179 CGF.Builder.CreateStore(getThisValue(CGF), CGF.ReturnValue); 1180 else if (hasMostDerivedReturn(CGF.CurGD)) 1181 CGF.Builder.CreateStore(CGF.EmitCastToVoidPtr(getThisValue(CGF)), 1182 CGF.ReturnValue); 1183 1184 const CXXMethodDecl *MD = cast<CXXMethodDecl>(CGF.CurGD.getDecl()); 1185 if (isa<CXXConstructorDecl>(MD) && MD->getParent()->getNumVBases()) { 1186 assert(getStructorImplicitParamDecl(CGF) && 1187 "no implicit parameter for a constructor with virtual bases?"); 1188 getStructorImplicitParamValue(CGF) 1189 = CGF.Builder.CreateLoad( 1190 CGF.GetAddrOfLocalVar(getStructorImplicitParamDecl(CGF)), 1191 "is_most_derived"); 1192 } 1193 1194 if (isDeletingDtor(CGF.CurGD)) { 1195 assert(getStructorImplicitParamDecl(CGF) && 1196 "no implicit parameter for a deleting destructor?"); 1197 getStructorImplicitParamValue(CGF) 1198 = CGF.Builder.CreateLoad( 1199 CGF.GetAddrOfLocalVar(getStructorImplicitParamDecl(CGF)), 1200 "should_call_delete"); 1201 } 1202} 1203 1204unsigned MicrosoftCXXABI::addImplicitConstructorArgs( 1205 CodeGenFunction &CGF, const CXXConstructorDecl *D, CXXCtorType Type, 1206 bool ForVirtualBase, bool Delegating, CallArgList &Args) { 1207 assert(Type == Ctor_Complete || Type == Ctor_Base); 1208 1209 // Check if we need a 'most_derived' parameter. 1210 if (!D->getParent()->getNumVBases()) 1211 return 0; 1212 1213 // Add the 'most_derived' argument second if we are variadic or last if not. 1214 const FunctionProtoType *FPT = D->getType()->castAs<FunctionProtoType>(); 1215 llvm::Value *MostDerivedArg = 1216 llvm::ConstantInt::get(CGM.Int32Ty, Type == Ctor_Complete); 1217 RValue RV = RValue::get(MostDerivedArg); 1218 if (MostDerivedArg) { 1219 if (FPT->isVariadic()) 1220 Args.insert(Args.begin() + 1, 1221 CallArg(RV, getContext().IntTy, /*needscopy=*/false)); 1222 else 1223 Args.add(RV, getContext().IntTy); 1224 } 1225 1226 return 1; // Added one arg. 1227} 1228 1229void MicrosoftCXXABI::EmitDestructorCall(CodeGenFunction &CGF, 1230 const CXXDestructorDecl *DD, 1231 CXXDtorType Type, bool ForVirtualBase, 1232 bool Delegating, llvm::Value *This) { 1233 llvm::Value *Callee = CGM.getAddrOfCXXStructor(DD, getFromDtorType(Type)); 1234 1235 if (DD->isVirtual()) { 1236 assert(Type != CXXDtorType::Dtor_Deleting && 1237 "The deleting destructor should only be called via a virtual call"); 1238 This = adjustThisArgumentForVirtualFunctionCall(CGF, GlobalDecl(DD, Type), 1239 This, false); 1240 } 1241 1242 CGF.EmitCXXStructorCall(DD, Callee, ReturnValueSlot(), This, 1243 /*ImplicitParam=*/nullptr, 1244 /*ImplicitParamTy=*/QualType(), nullptr, 1245 getFromDtorType(Type)); 1246} 1247 1248void MicrosoftCXXABI::emitVTableDefinitions(CodeGenVTables &CGVT, 1249 const CXXRecordDecl *RD) { 1250 MicrosoftVTableContext &VFTContext = CGM.getMicrosoftVTableContext(); 1251 const VPtrInfoVector &VFPtrs = VFTContext.getVFPtrOffsets(RD); 1252 1253 for (VPtrInfo *Info : VFPtrs) { 1254 llvm::GlobalVariable *VTable = getAddrOfVTable(RD, Info->FullOffsetInMDC); 1255 if (VTable->hasInitializer()) 1256 continue; 1257 1258 llvm::Constant *RTTI = getContext().getLangOpts().RTTIData 1259 ? getMSCompleteObjectLocator(RD, Info) 1260 : nullptr; 1261 1262 const VTableLayout &VTLayout = 1263 VFTContext.getVFTableLayout(RD, Info->FullOffsetInMDC); 1264 llvm::Constant *Init = CGVT.CreateVTableInitializer( 1265 RD, VTLayout.vtable_component_begin(), 1266 VTLayout.getNumVTableComponents(), VTLayout.vtable_thunk_begin(), 1267 VTLayout.getNumVTableThunks(), RTTI); 1268 1269 VTable->setInitializer(Init); 1270 } 1271} 1272 1273llvm::Value *MicrosoftCXXABI::getVTableAddressPointInStructor( 1274 CodeGenFunction &CGF, const CXXRecordDecl *VTableClass, BaseSubobject Base, 1275 const CXXRecordDecl *NearestVBase, bool &NeedsVirtualOffset) { 1276 NeedsVirtualOffset = (NearestVBase != nullptr); 1277 1278 (void)getAddrOfVTable(VTableClass, Base.getBaseOffset()); 1279 VFTableIdTy ID(VTableClass, Base.getBaseOffset()); 1280 llvm::GlobalValue *VTableAddressPoint = VFTablesMap[ID]; 1281 if (!VTableAddressPoint) { 1282 assert(Base.getBase()->getNumVBases() && 1283 !CGM.getContext().getASTRecordLayout(Base.getBase()).hasOwnVFPtr()); 1284 } 1285 return VTableAddressPoint; 1286} 1287 1288static void mangleVFTableName(MicrosoftMangleContext &MangleContext, 1289 const CXXRecordDecl *RD, const VPtrInfo *VFPtr, 1290 SmallString<256> &Name) { 1291 llvm::raw_svector_ostream Out(Name); 1292 MangleContext.mangleCXXVFTable(RD, VFPtr->MangledPath, Out); 1293} 1294 1295llvm::Constant *MicrosoftCXXABI::getVTableAddressPointForConstExpr( 1296 BaseSubobject Base, const CXXRecordDecl *VTableClass) { 1297 (void)getAddrOfVTable(VTableClass, Base.getBaseOffset()); 1298 VFTableIdTy ID(VTableClass, Base.getBaseOffset()); 1299 llvm::GlobalValue *VFTable = VFTablesMap[ID]; 1300 assert(VFTable && "Couldn't find a vftable for the given base?"); 1301 return VFTable; 1302} 1303 1304llvm::GlobalVariable *MicrosoftCXXABI::getAddrOfVTable(const CXXRecordDecl *RD, 1305 CharUnits VPtrOffset) { 1306 // getAddrOfVTable may return 0 if asked to get an address of a vtable which 1307 // shouldn't be used in the given record type. We want to cache this result in 1308 // VFTablesMap, thus a simple zero check is not sufficient. 1309 VFTableIdTy ID(RD, VPtrOffset); 1310 VTablesMapTy::iterator I; 1311 bool Inserted; 1312 std::tie(I, Inserted) = VTablesMap.insert(std::make_pair(ID, nullptr)); 1313 if (!Inserted) 1314 return I->second; 1315 1316 llvm::GlobalVariable *&VTable = I->second; 1317 1318 MicrosoftVTableContext &VTContext = CGM.getMicrosoftVTableContext(); 1319 const VPtrInfoVector &VFPtrs = VTContext.getVFPtrOffsets(RD); 1320 1321 if (DeferredVFTables.insert(RD).second) { 1322 // We haven't processed this record type before. 1323 // Queue up this v-table for possible deferred emission. 1324 CGM.addDeferredVTable(RD); 1325 1326#ifndef NDEBUG 1327 // Create all the vftables at once in order to make sure each vftable has 1328 // a unique mangled name. 1329 llvm::StringSet<> ObservedMangledNames; 1330 for (size_t J = 0, F = VFPtrs.size(); J != F; ++J) { 1331 SmallString<256> Name; 1332 mangleVFTableName(getMangleContext(), RD, VFPtrs[J], Name); 1333 if (!ObservedMangledNames.insert(Name.str()).second) 1334 llvm_unreachable("Already saw this mangling before?"); 1335 } 1336#endif 1337 } 1338 1339 for (size_t J = 0, F = VFPtrs.size(); J != F; ++J) { 1340 if (VFPtrs[J]->FullOffsetInMDC != VPtrOffset) 1341 continue; 1342 SmallString<256> VFTableName; 1343 mangleVFTableName(getMangleContext(), RD, VFPtrs[J], VFTableName); 1344 StringRef VTableName = VFTableName; 1345 1346 uint64_t NumVTableSlots = 1347 VTContext.getVFTableLayout(RD, VFPtrs[J]->FullOffsetInMDC) 1348 .getNumVTableComponents(); 1349 llvm::GlobalValue::LinkageTypes VTableLinkage = 1350 llvm::GlobalValue::ExternalLinkage; 1351 llvm::ArrayType *VTableType = 1352 llvm::ArrayType::get(CGM.Int8PtrTy, NumVTableSlots); 1353 if (getContext().getLangOpts().RTTIData) { 1354 VTableLinkage = llvm::GlobalValue::PrivateLinkage; 1355 VTableName = ""; 1356 } 1357 1358 VTable = CGM.getModule().getNamedGlobal(VFTableName); 1359 if (!VTable) { 1360 // Create a backing variable for the contents of VTable. The VTable may 1361 // or may not include space for a pointer to RTTI data. 1362 llvm::GlobalValue *VFTable = VTable = new llvm::GlobalVariable( 1363 CGM.getModule(), VTableType, /*isConstant=*/true, VTableLinkage, 1364 /*Initializer=*/nullptr, VTableName); 1365 VTable->setUnnamedAddr(true); 1366 1367 // Only insert a pointer into the VFTable for RTTI data if we are not 1368 // importing it. We never reference the RTTI data directly so there is no 1369 // need to make room for it. 1370 if (getContext().getLangOpts().RTTIData && 1371 !RD->hasAttr<DLLImportAttr>()) { 1372 llvm::Value *GEPIndices[] = {llvm::ConstantInt::get(CGM.IntTy, 0), 1373 llvm::ConstantInt::get(CGM.IntTy, 1)}; 1374 // Create a GEP which points just after the first entry in the VFTable, 1375 // this should be the location of the first virtual method. 1376 llvm::Constant *VTableGEP = 1377 llvm::ConstantExpr::getInBoundsGetElementPtr(VTable, GEPIndices); 1378 // The symbol for the VFTable is an alias to the GEP. It is 1379 // transparent, to other modules, what the nature of this symbol is; all 1380 // that matters is that the alias be the address of the first virtual 1381 // method. 1382 VFTable = llvm::GlobalAlias::create( 1383 cast<llvm::SequentialType>(VTableGEP->getType())->getElementType(), 1384 /*AddressSpace=*/0, llvm::GlobalValue::ExternalLinkage, 1385 VFTableName.str(), VTableGEP, &CGM.getModule()); 1386 } else { 1387 // We don't need a GlobalAlias to be a symbol for the VTable if we won't 1388 // be referencing any RTTI data. The GlobalVariable will end up being 1389 // an appropriate definition of the VFTable. 1390 VTable->setName(VFTableName.str()); 1391 } 1392 1393 VFTable->setUnnamedAddr(true); 1394 if (RD->hasAttr<DLLImportAttr>()) 1395 VFTable->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass); 1396 else if (RD->hasAttr<DLLExportAttr>()) 1397 VFTable->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass); 1398 1399 llvm::GlobalValue::LinkageTypes VFTableLinkage = CGM.getVTableLinkage(RD); 1400 if (VFTable != VTable) { 1401 if (llvm::GlobalValue::isAvailableExternallyLinkage(VFTableLinkage)) { 1402 // AvailableExternally implies that we grabbed the data from another 1403 // executable. No need to stick the alias in a Comdat. 1404 } else if (llvm::GlobalValue::isInternalLinkage(VFTableLinkage) || 1405 llvm::GlobalValue::isWeakODRLinkage(VFTableLinkage) || 1406 llvm::GlobalValue::isLinkOnceODRLinkage(VFTableLinkage)) { 1407 // The alias is going to be dropped into a Comdat, no need to make it 1408 // weak. 1409 if (!llvm::GlobalValue::isInternalLinkage(VFTableLinkage)) 1410 VFTableLinkage = llvm::GlobalValue::ExternalLinkage; 1411 llvm::Comdat *C = 1412 CGM.getModule().getOrInsertComdat(VFTable->getName()); 1413 // We must indicate which VFTable is larger to support linking between 1414 // translation units which do and do not have RTTI data. The largest 1415 // VFTable contains the RTTI data; translation units which reference 1416 // the smaller VFTable always reference it relative to the first 1417 // virtual method. 1418 C->setSelectionKind(llvm::Comdat::Largest); 1419 VTable->setComdat(C); 1420 } else { 1421 llvm_unreachable("unexpected linkage for vftable!"); 1422 } 1423 } 1424 VFTable->setLinkage(VFTableLinkage); 1425 CGM.setGlobalVisibility(VFTable, RD); 1426 VFTablesMap[ID] = VFTable; 1427 } 1428 break; 1429 } 1430 1431 return VTable; 1432} 1433 1434llvm::Value *MicrosoftCXXABI::getVirtualFunctionPointer(CodeGenFunction &CGF, 1435 GlobalDecl GD, 1436 llvm::Value *This, 1437 llvm::Type *Ty) { 1438 GD = GD.getCanonicalDecl(); 1439 CGBuilderTy &Builder = CGF.Builder; 1440 1441 Ty = Ty->getPointerTo()->getPointerTo(); 1442 llvm::Value *VPtr = 1443 adjustThisArgumentForVirtualFunctionCall(CGF, GD, This, true); 1444 llvm::Value *VTable = CGF.GetVTablePtr(VPtr, Ty); 1445 1446 MicrosoftVTableContext::MethodVFTableLocation ML = 1447 CGM.getMicrosoftVTableContext().getMethodVFTableLocation(GD); 1448 llvm::Value *VFuncPtr = 1449 Builder.CreateConstInBoundsGEP1_64(VTable, ML.Index, "vfn"); 1450 return Builder.CreateLoad(VFuncPtr); 1451} 1452 1453llvm::Value *MicrosoftCXXABI::EmitVirtualDestructorCall( 1454 CodeGenFunction &CGF, const CXXDestructorDecl *Dtor, CXXDtorType DtorType, 1455 llvm::Value *This, const CXXMemberCallExpr *CE) { 1456 assert(CE == nullptr || CE->arg_begin() == CE->arg_end()); 1457 assert(DtorType == Dtor_Deleting || DtorType == Dtor_Complete); 1458 1459 // We have only one destructor in the vftable but can get both behaviors 1460 // by passing an implicit int parameter. 1461 GlobalDecl GD(Dtor, Dtor_Deleting); 1462 const CGFunctionInfo *FInfo = &CGM.getTypes().arrangeCXXStructorDeclaration( 1463 Dtor, StructorType::Deleting); 1464 llvm::Type *Ty = CGF.CGM.getTypes().GetFunctionType(*FInfo); 1465 llvm::Value *Callee = getVirtualFunctionPointer(CGF, GD, This, Ty); 1466 1467 ASTContext &Context = CGF.getContext(); 1468 llvm::Value *ImplicitParam = llvm::ConstantInt::get( 1469 llvm::IntegerType::getInt32Ty(CGF.getLLVMContext()), 1470 DtorType == Dtor_Deleting); 1471 1472 This = adjustThisArgumentForVirtualFunctionCall(CGF, GD, This, true); 1473 RValue RV = CGF.EmitCXXStructorCall(Dtor, Callee, ReturnValueSlot(), This, 1474 ImplicitParam, Context.IntTy, CE, 1475 StructorType::Deleting); 1476 return RV.getScalarVal(); 1477} 1478 1479const VBTableGlobals & 1480MicrosoftCXXABI::enumerateVBTables(const CXXRecordDecl *RD) { 1481 // At this layer, we can key the cache off of a single class, which is much 1482 // easier than caching each vbtable individually. 1483 llvm::DenseMap<const CXXRecordDecl*, VBTableGlobals>::iterator Entry; 1484 bool Added; 1485 std::tie(Entry, Added) = 1486 VBTablesMap.insert(std::make_pair(RD, VBTableGlobals())); 1487 VBTableGlobals &VBGlobals = Entry->second; 1488 if (!Added) 1489 return VBGlobals; 1490 1491 MicrosoftVTableContext &Context = CGM.getMicrosoftVTableContext(); 1492 VBGlobals.VBTables = &Context.enumerateVBTables(RD); 1493 1494 // Cache the globals for all vbtables so we don't have to recompute the 1495 // mangled names. 1496 llvm::GlobalVariable::LinkageTypes Linkage = CGM.getVTableLinkage(RD); 1497 for (VPtrInfoVector::const_iterator I = VBGlobals.VBTables->begin(), 1498 E = VBGlobals.VBTables->end(); 1499 I != E; ++I) { 1500 VBGlobals.Globals.push_back(getAddrOfVBTable(**I, RD, Linkage)); 1501 } 1502 1503 return VBGlobals; 1504} 1505 1506llvm::Function *MicrosoftCXXABI::EmitVirtualMemPtrThunk( 1507 const CXXMethodDecl *MD, 1508 const MicrosoftVTableContext::MethodVFTableLocation &ML) { 1509 assert(!isa<CXXConstructorDecl>(MD) && !isa<CXXDestructorDecl>(MD) && 1510 "can't form pointers to ctors or virtual dtors"); 1511 1512 // Calculate the mangled name. 1513 SmallString<256> ThunkName; 1514 llvm::raw_svector_ostream Out(ThunkName); 1515 getMangleContext().mangleVirtualMemPtrThunk(MD, Out); 1516 Out.flush(); 1517 1518 // If the thunk has been generated previously, just return it. 1519 if (llvm::GlobalValue *GV = CGM.getModule().getNamedValue(ThunkName)) 1520 return cast<llvm::Function>(GV); 1521 1522 // Create the llvm::Function. 1523 const CGFunctionInfo &FnInfo = CGM.getTypes().arrangeMSMemberPointerThunk(MD); 1524 llvm::FunctionType *ThunkTy = CGM.getTypes().GetFunctionType(FnInfo); 1525 llvm::Function *ThunkFn = 1526 llvm::Function::Create(ThunkTy, llvm::Function::ExternalLinkage, 1527 ThunkName.str(), &CGM.getModule()); 1528 assert(ThunkFn->getName() == ThunkName && "name was uniqued!"); 1529 1530 ThunkFn->setLinkage(MD->isExternallyVisible() 1531 ? llvm::GlobalValue::LinkOnceODRLinkage 1532 : llvm::GlobalValue::InternalLinkage); 1533 1534 CGM.SetLLVMFunctionAttributes(MD, FnInfo, ThunkFn); 1535 CGM.SetLLVMFunctionAttributesForDefinition(MD, ThunkFn); 1536 1537 // Add the "thunk" attribute so that LLVM knows that the return type is 1538 // meaningless. These thunks can be used to call functions with differing 1539 // return types, and the caller is required to cast the prototype 1540 // appropriately to extract the correct value. 1541 ThunkFn->addFnAttr("thunk"); 1542 1543 // These thunks can be compared, so they are not unnamed. 1544 ThunkFn->setUnnamedAddr(false); 1545 1546 // Start codegen. 1547 CodeGenFunction CGF(CGM); 1548 CGF.CurGD = GlobalDecl(MD); 1549 CGF.CurFuncIsThunk = true; 1550 1551 // Build FunctionArgs, but only include the implicit 'this' parameter 1552 // declaration. 1553 FunctionArgList FunctionArgs; 1554 buildThisParam(CGF, FunctionArgs); 1555 1556 // Start defining the function. 1557 CGF.StartFunction(GlobalDecl(), FnInfo.getReturnType(), ThunkFn, FnInfo, 1558 FunctionArgs, MD->getLocation(), SourceLocation()); 1559 EmitThisParam(CGF); 1560 1561 // Load the vfptr and then callee from the vftable. The callee should have 1562 // adjusted 'this' so that the vfptr is at offset zero. 1563 llvm::Value *VTable = CGF.GetVTablePtr( 1564 getThisValue(CGF), ThunkTy->getPointerTo()->getPointerTo()); 1565 llvm::Value *VFuncPtr = 1566 CGF.Builder.CreateConstInBoundsGEP1_64(VTable, ML.Index, "vfn"); 1567 llvm::Value *Callee = CGF.Builder.CreateLoad(VFuncPtr); 1568 1569 CGF.EmitMustTailThunk(MD, getThisValue(CGF), Callee); 1570 1571 return ThunkFn; 1572} 1573 1574void MicrosoftCXXABI::emitVirtualInheritanceTables(const CXXRecordDecl *RD) { 1575 const VBTableGlobals &VBGlobals = enumerateVBTables(RD); 1576 for (unsigned I = 0, E = VBGlobals.VBTables->size(); I != E; ++I) { 1577 const VPtrInfo *VBT = (*VBGlobals.VBTables)[I]; 1578 llvm::GlobalVariable *GV = VBGlobals.Globals[I]; 1579 emitVBTableDefinition(*VBT, RD, GV); 1580 } 1581} 1582 1583llvm::GlobalVariable * 1584MicrosoftCXXABI::getAddrOfVBTable(const VPtrInfo &VBT, const CXXRecordDecl *RD, 1585 llvm::GlobalVariable::LinkageTypes Linkage) { 1586 SmallString<256> OutName; 1587 llvm::raw_svector_ostream Out(OutName); 1588 getMangleContext().mangleCXXVBTable(RD, VBT.MangledPath, Out); 1589 Out.flush(); 1590 StringRef Name = OutName.str(); 1591 1592 llvm::ArrayType *VBTableType = 1593 llvm::ArrayType::get(CGM.IntTy, 1 + VBT.ReusingBase->getNumVBases()); 1594 1595 assert(!CGM.getModule().getNamedGlobal(Name) && 1596 "vbtable with this name already exists: mangling bug?"); 1597 llvm::GlobalVariable *GV = 1598 CGM.CreateOrReplaceCXXRuntimeVariable(Name, VBTableType, Linkage); 1599 GV->setUnnamedAddr(true); 1600 1601 if (RD->hasAttr<DLLImportAttr>()) 1602 GV->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass); 1603 else if (RD->hasAttr<DLLExportAttr>()) 1604 GV->setDLLStorageClass(llvm::GlobalValue::DLLExportStorageClass); 1605 1606 return GV; 1607} 1608 1609void MicrosoftCXXABI::emitVBTableDefinition(const VPtrInfo &VBT, 1610 const CXXRecordDecl *RD, 1611 llvm::GlobalVariable *GV) const { 1612 const CXXRecordDecl *ReusingBase = VBT.ReusingBase; 1613 1614 assert(RD->getNumVBases() && ReusingBase->getNumVBases() && 1615 "should only emit vbtables for classes with vbtables"); 1616 1617 const ASTRecordLayout &BaseLayout = 1618 CGM.getContext().getASTRecordLayout(VBT.BaseWithVPtr); 1619 const ASTRecordLayout &DerivedLayout = 1620 CGM.getContext().getASTRecordLayout(RD); 1621 1622 SmallVector<llvm::Constant *, 4> Offsets(1 + ReusingBase->getNumVBases(), 1623 nullptr); 1624 1625 // The offset from ReusingBase's vbptr to itself always leads. 1626 CharUnits VBPtrOffset = BaseLayout.getVBPtrOffset(); 1627 Offsets[0] = llvm::ConstantInt::get(CGM.IntTy, -VBPtrOffset.getQuantity()); 1628 1629 MicrosoftVTableContext &Context = CGM.getMicrosoftVTableContext(); 1630 for (const auto &I : ReusingBase->vbases()) { 1631 const CXXRecordDecl *VBase = I.getType()->getAsCXXRecordDecl(); 1632 CharUnits Offset = DerivedLayout.getVBaseClassOffset(VBase); 1633 assert(!Offset.isNegative()); 1634 1635 // Make it relative to the subobject vbptr. 1636 CharUnits CompleteVBPtrOffset = VBT.NonVirtualOffset + VBPtrOffset; 1637 if (VBT.getVBaseWithVPtr()) 1638 CompleteVBPtrOffset += 1639 DerivedLayout.getVBaseClassOffset(VBT.getVBaseWithVPtr()); 1640 Offset -= CompleteVBPtrOffset; 1641 1642 unsigned VBIndex = Context.getVBTableIndex(ReusingBase, VBase); 1643 assert(Offsets[VBIndex] == nullptr && "The same vbindex seen twice?"); 1644 Offsets[VBIndex] = llvm::ConstantInt::get(CGM.IntTy, Offset.getQuantity()); 1645 } 1646 1647 assert(Offsets.size() == 1648 cast<llvm::ArrayType>(cast<llvm::PointerType>(GV->getType()) 1649 ->getElementType())->getNumElements()); 1650 llvm::ArrayType *VBTableType = 1651 llvm::ArrayType::get(CGM.IntTy, Offsets.size()); 1652 llvm::Constant *Init = llvm::ConstantArray::get(VBTableType, Offsets); 1653 GV->setInitializer(Init); 1654 1655 // Set the right visibility. 1656 CGM.setGlobalVisibility(GV, RD); 1657} 1658 1659llvm::Value *MicrosoftCXXABI::performThisAdjustment(CodeGenFunction &CGF, 1660 llvm::Value *This, 1661 const ThisAdjustment &TA) { 1662 if (TA.isEmpty()) 1663 return This; 1664 1665 llvm::Value *V = CGF.Builder.CreateBitCast(This, CGF.Int8PtrTy); 1666 1667 if (!TA.Virtual.isEmpty()) { 1668 assert(TA.Virtual.Microsoft.VtordispOffset < 0); 1669 // Adjust the this argument based on the vtordisp value. 1670 llvm::Value *VtorDispPtr = 1671 CGF.Builder.CreateConstGEP1_32(V, TA.Virtual.Microsoft.VtordispOffset); 1672 VtorDispPtr = 1673 CGF.Builder.CreateBitCast(VtorDispPtr, CGF.Int32Ty->getPointerTo()); 1674 llvm::Value *VtorDisp = CGF.Builder.CreateLoad(VtorDispPtr, "vtordisp"); 1675 V = CGF.Builder.CreateGEP(V, CGF.Builder.CreateNeg(VtorDisp)); 1676 1677 if (TA.Virtual.Microsoft.VBPtrOffset) { 1678 // If the final overrider is defined in a virtual base other than the one 1679 // that holds the vfptr, we have to use a vtordispex thunk which looks up 1680 // the vbtable of the derived class. 1681 assert(TA.Virtual.Microsoft.VBPtrOffset > 0); 1682 assert(TA.Virtual.Microsoft.VBOffsetOffset >= 0); 1683 llvm::Value *VBPtr; 1684 llvm::Value *VBaseOffset = 1685 GetVBaseOffsetFromVBPtr(CGF, V, -TA.Virtual.Microsoft.VBPtrOffset, 1686 TA.Virtual.Microsoft.VBOffsetOffset, &VBPtr); 1687 V = CGF.Builder.CreateInBoundsGEP(VBPtr, VBaseOffset); 1688 } 1689 } 1690 1691 if (TA.NonVirtual) { 1692 // Non-virtual adjustment might result in a pointer outside the allocated 1693 // object, e.g. if the final overrider class is laid out after the virtual 1694 // base that declares a method in the most derived class. 1695 V = CGF.Builder.CreateConstGEP1_32(V, TA.NonVirtual); 1696 } 1697 1698 // Don't need to bitcast back, the call CodeGen will handle this. 1699 return V; 1700} 1701 1702llvm::Value * 1703MicrosoftCXXABI::performReturnAdjustment(CodeGenFunction &CGF, llvm::Value *Ret, 1704 const ReturnAdjustment &RA) { 1705 if (RA.isEmpty()) 1706 return Ret; 1707 1708 llvm::Value *V = CGF.Builder.CreateBitCast(Ret, CGF.Int8PtrTy); 1709 1710 if (RA.Virtual.Microsoft.VBIndex) { 1711 assert(RA.Virtual.Microsoft.VBIndex > 0); 1712 int32_t IntSize = 1713 getContext().getTypeSizeInChars(getContext().IntTy).getQuantity(); 1714 llvm::Value *VBPtr; 1715 llvm::Value *VBaseOffset = 1716 GetVBaseOffsetFromVBPtr(CGF, V, RA.Virtual.Microsoft.VBPtrOffset, 1717 IntSize * RA.Virtual.Microsoft.VBIndex, &VBPtr); 1718 V = CGF.Builder.CreateInBoundsGEP(VBPtr, VBaseOffset); 1719 } 1720 1721 if (RA.NonVirtual) 1722 V = CGF.Builder.CreateConstInBoundsGEP1_32(V, RA.NonVirtual); 1723 1724 // Cast back to the original type. 1725 return CGF.Builder.CreateBitCast(V, Ret->getType()); 1726} 1727 1728bool MicrosoftCXXABI::requiresArrayCookie(const CXXDeleteExpr *expr, 1729 QualType elementType) { 1730 // Microsoft seems to completely ignore the possibility of a 1731 // two-argument usual deallocation function. 1732 return elementType.isDestructedType(); 1733} 1734 1735bool MicrosoftCXXABI::requiresArrayCookie(const CXXNewExpr *expr) { 1736 // Microsoft seems to completely ignore the possibility of a 1737 // two-argument usual deallocation function. 1738 return expr->getAllocatedType().isDestructedType(); 1739} 1740 1741CharUnits MicrosoftCXXABI::getArrayCookieSizeImpl(QualType type) { 1742 // The array cookie is always a size_t; we then pad that out to the 1743 // alignment of the element type. 1744 ASTContext &Ctx = getContext(); 1745 return std::max(Ctx.getTypeSizeInChars(Ctx.getSizeType()), 1746 Ctx.getTypeAlignInChars(type)); 1747} 1748 1749llvm::Value *MicrosoftCXXABI::readArrayCookieImpl(CodeGenFunction &CGF, 1750 llvm::Value *allocPtr, 1751 CharUnits cookieSize) { 1752 unsigned AS = allocPtr->getType()->getPointerAddressSpace(); 1753 llvm::Value *numElementsPtr = 1754 CGF.Builder.CreateBitCast(allocPtr, CGF.SizeTy->getPointerTo(AS)); 1755 return CGF.Builder.CreateLoad(numElementsPtr); 1756} 1757 1758llvm::Value* MicrosoftCXXABI::InitializeArrayCookie(CodeGenFunction &CGF, 1759 llvm::Value *newPtr, 1760 llvm::Value *numElements, 1761 const CXXNewExpr *expr, 1762 QualType elementType) { 1763 assert(requiresArrayCookie(expr)); 1764 1765 // The size of the cookie. 1766 CharUnits cookieSize = getArrayCookieSizeImpl(elementType); 1767 1768 // Compute an offset to the cookie. 1769 llvm::Value *cookiePtr = newPtr; 1770 1771 // Write the number of elements into the appropriate slot. 1772 unsigned AS = newPtr->getType()->getPointerAddressSpace(); 1773 llvm::Value *numElementsPtr 1774 = CGF.Builder.CreateBitCast(cookiePtr, CGF.SizeTy->getPointerTo(AS)); 1775 CGF.Builder.CreateStore(numElements, numElementsPtr); 1776 1777 // Finally, compute a pointer to the actual data buffer by skipping 1778 // over the cookie completely. 1779 return CGF.Builder.CreateConstInBoundsGEP1_64(newPtr, 1780 cookieSize.getQuantity()); 1781} 1782 1783static void emitGlobalDtorWithTLRegDtor(CodeGenFunction &CGF, const VarDecl &VD, 1784 llvm::Constant *Dtor, 1785 llvm::Constant *Addr) { 1786 // Create a function which calls the destructor. 1787 llvm::Constant *DtorStub = CGF.createAtExitStub(VD, Dtor, Addr); 1788 1789 // extern "C" int __tlregdtor(void (*f)(void)); 1790 llvm::FunctionType *TLRegDtorTy = llvm::FunctionType::get( 1791 CGF.IntTy, DtorStub->getType(), /*IsVarArg=*/false); 1792 1793 llvm::Constant *TLRegDtor = 1794 CGF.CGM.CreateRuntimeFunction(TLRegDtorTy, "__tlregdtor"); 1795 if (llvm::Function *TLRegDtorFn = dyn_cast<llvm::Function>(TLRegDtor)) 1796 TLRegDtorFn->setDoesNotThrow(); 1797 1798 CGF.EmitNounwindRuntimeCall(TLRegDtor, DtorStub); 1799} 1800 1801void MicrosoftCXXABI::registerGlobalDtor(CodeGenFunction &CGF, const VarDecl &D, 1802 llvm::Constant *Dtor, 1803 llvm::Constant *Addr) { 1804 if (D.getTLSKind()) 1805 return emitGlobalDtorWithTLRegDtor(CGF, D, Dtor, Addr); 1806 1807 // The default behavior is to use atexit. 1808 CGF.registerGlobalDtorWithAtExit(D, Dtor, Addr); 1809} 1810 1811void MicrosoftCXXABI::EmitThreadLocalInitFuncs( 1812 CodeGenModule &CGM, 1813 ArrayRef<std::pair<const VarDecl *, llvm::GlobalVariable *>> 1814 CXXThreadLocals, 1815 ArrayRef<llvm::Function *> CXXThreadLocalInits, 1816 ArrayRef<llvm::GlobalVariable *> CXXThreadLocalInitVars) { 1817 // This will create a GV in the .CRT$XDU section. It will point to our 1818 // initialization function. The CRT will call all of these function 1819 // pointers at start-up time and, eventually, at thread-creation time. 1820 auto AddToXDU = [&CGM](llvm::Function *InitFunc) { 1821 llvm::GlobalVariable *InitFuncPtr = new llvm::GlobalVariable( 1822 CGM.getModule(), InitFunc->getType(), /*IsConstant=*/true, 1823 llvm::GlobalVariable::InternalLinkage, InitFunc, 1824 Twine(InitFunc->getName(), "$initializer$")); 1825 InitFuncPtr->setSection(".CRT$XDU"); 1826 // This variable has discardable linkage, we have to add it to @llvm.used to 1827 // ensure it won't get discarded. 1828 CGM.addUsedGlobal(InitFuncPtr); 1829 return InitFuncPtr; 1830 }; 1831 1832 std::vector<llvm::Function *> NonComdatInits; 1833 for (size_t I = 0, E = CXXThreadLocalInitVars.size(); I != E; ++I) { 1834 llvm::GlobalVariable *GV = CXXThreadLocalInitVars[I]; 1835 llvm::Function *F = CXXThreadLocalInits[I]; 1836 1837 // If the GV is already in a comdat group, then we have to join it. 1838 llvm::Comdat *C = GV->getComdat(); 1839 1840 // LinkOnce and Weak linkage are lowered down to a single-member comdat 1841 // group. 1842 // Make an explicit group so we can join it. 1843 if (!C && (GV->hasWeakLinkage() || GV->hasLinkOnceLinkage())) { 1844 C = CGM.getModule().getOrInsertComdat(GV->getName()); 1845 GV->setComdat(C); 1846 AddToXDU(F)->setComdat(C); 1847 } else { 1848 NonComdatInits.push_back(F); 1849 } 1850 } 1851 1852 if (!NonComdatInits.empty()) { 1853 llvm::FunctionType *FTy = 1854 llvm::FunctionType::get(CGM.VoidTy, /*isVarArg=*/false); 1855 llvm::Function *InitFunc = CGM.CreateGlobalInitOrDestructFunction( 1856 FTy, "__tls_init", SourceLocation(), 1857 /*TLS=*/true); 1858 CodeGenFunction(CGM).GenerateCXXGlobalInitFunc(InitFunc, NonComdatInits); 1859 1860 AddToXDU(InitFunc); 1861 } 1862} 1863 1864LValue MicrosoftCXXABI::EmitThreadLocalVarDeclLValue(CodeGenFunction &CGF, 1865 const VarDecl *VD, 1866 QualType LValType) { 1867 CGF.CGM.ErrorUnsupported(VD, "thread wrappers"); 1868 return LValue(); 1869} 1870 1871void MicrosoftCXXABI::EmitGuardedInit(CodeGenFunction &CGF, const VarDecl &D, 1872 llvm::GlobalVariable *GV, 1873 bool PerformInit) { 1874 // MSVC only uses guards for static locals. 1875 if (!D.isStaticLocal()) { 1876 assert(GV->hasWeakLinkage() || GV->hasLinkOnceLinkage()); 1877 // GlobalOpt is allowed to discard the initializer, so use linkonce_odr. 1878 CGF.CurFn->setLinkage(llvm::GlobalValue::LinkOnceODRLinkage); 1879 CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit); 1880 return; 1881 } 1882 1883 // MSVC always uses an i32 bitfield to guard initialization, which is *not* 1884 // threadsafe. Since the user may be linking in inline functions compiled by 1885 // cl.exe, there's no reason to provide a false sense of security by using 1886 // critical sections here. 1887 1888 if (D.getTLSKind()) 1889 CGM.ErrorUnsupported(&D, "dynamic TLS initialization"); 1890 1891 CGBuilderTy &Builder = CGF.Builder; 1892 llvm::IntegerType *GuardTy = CGF.Int32Ty; 1893 llvm::ConstantInt *Zero = llvm::ConstantInt::get(GuardTy, 0); 1894 1895 // Get the guard variable for this function if we have one already. 1896 GuardInfo *GI = &GuardVariableMap[D.getDeclContext()]; 1897 1898 unsigned BitIndex; 1899 if (D.isStaticLocal() && D.isExternallyVisible()) { 1900 // Externally visible variables have to be numbered in Sema to properly 1901 // handle unreachable VarDecls. 1902 BitIndex = getContext().getStaticLocalNumber(&D); 1903 assert(BitIndex > 0); 1904 BitIndex--; 1905 } else { 1906 // Non-externally visible variables are numbered here in CodeGen. 1907 BitIndex = GI->BitIndex++; 1908 } 1909 1910 if (BitIndex >= 32) { 1911 if (D.isExternallyVisible()) 1912 ErrorUnsupportedABI(CGF, "more than 32 guarded initializations"); 1913 BitIndex %= 32; 1914 GI->Guard = nullptr; 1915 } 1916 1917 // Lazily create the i32 bitfield for this function. 1918 if (!GI->Guard) { 1919 // Mangle the name for the guard. 1920 SmallString<256> GuardName; 1921 { 1922 llvm::raw_svector_ostream Out(GuardName); 1923 getMangleContext().mangleStaticGuardVariable(&D, Out); 1924 Out.flush(); 1925 } 1926 1927 // Create the guard variable with a zero-initializer. Just absorb linkage, 1928 // visibility and dll storage class from the guarded variable. 1929 GI->Guard = 1930 new llvm::GlobalVariable(CGM.getModule(), GuardTy, false, 1931 GV->getLinkage(), Zero, GuardName.str()); 1932 GI->Guard->setVisibility(GV->getVisibility()); 1933 GI->Guard->setDLLStorageClass(GV->getDLLStorageClass()); 1934 } else { 1935 assert(GI->Guard->getLinkage() == GV->getLinkage() && 1936 "static local from the same function had different linkage"); 1937 } 1938 1939 // Pseudo code for the test: 1940 // if (!(GuardVar & MyGuardBit)) { 1941 // GuardVar |= MyGuardBit; 1942 // ... initialize the object ...; 1943 // } 1944 1945 // Test our bit from the guard variable. 1946 llvm::ConstantInt *Bit = llvm::ConstantInt::get(GuardTy, 1U << BitIndex); 1947 llvm::LoadInst *LI = Builder.CreateLoad(GI->Guard); 1948 llvm::Value *IsInitialized = 1949 Builder.CreateICmpNE(Builder.CreateAnd(LI, Bit), Zero); 1950 llvm::BasicBlock *InitBlock = CGF.createBasicBlock("init"); 1951 llvm::BasicBlock *EndBlock = CGF.createBasicBlock("init.end"); 1952 Builder.CreateCondBr(IsInitialized, EndBlock, InitBlock); 1953 1954 // Set our bit in the guard variable and emit the initializer and add a global 1955 // destructor if appropriate. 1956 CGF.EmitBlock(InitBlock); 1957 Builder.CreateStore(Builder.CreateOr(LI, Bit), GI->Guard); 1958 CGF.EmitCXXGlobalVarDeclInit(D, GV, PerformInit); 1959 Builder.CreateBr(EndBlock); 1960 1961 // Continue. 1962 CGF.EmitBlock(EndBlock); 1963} 1964 1965bool MicrosoftCXXABI::isZeroInitializable(const MemberPointerType *MPT) { 1966 // Null-ness for function memptrs only depends on the first field, which is 1967 // the function pointer. The rest don't matter, so we can zero initialize. 1968 if (MPT->isMemberFunctionPointer()) 1969 return true; 1970 1971 // The virtual base adjustment field is always -1 for null, so if we have one 1972 // we can't zero initialize. The field offset is sometimes also -1 if 0 is a 1973 // valid field offset. 1974 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl(); 1975 MSInheritanceAttr::Spelling Inheritance = RD->getMSInheritanceModel(); 1976 return (!MSInheritanceAttr::hasVBTableOffsetField(Inheritance) && 1977 RD->nullFieldOffsetIsZero()); 1978} 1979 1980llvm::Type * 1981MicrosoftCXXABI::ConvertMemberPointerType(const MemberPointerType *MPT) { 1982 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl(); 1983 MSInheritanceAttr::Spelling Inheritance = RD->getMSInheritanceModel(); 1984 llvm::SmallVector<llvm::Type *, 4> fields; 1985 if (MPT->isMemberFunctionPointer()) 1986 fields.push_back(CGM.VoidPtrTy); // FunctionPointerOrVirtualThunk 1987 else 1988 fields.push_back(CGM.IntTy); // FieldOffset 1989 1990 if (MSInheritanceAttr::hasNVOffsetField(MPT->isMemberFunctionPointer(), 1991 Inheritance)) 1992 fields.push_back(CGM.IntTy); 1993 if (MSInheritanceAttr::hasVBPtrOffsetField(Inheritance)) 1994 fields.push_back(CGM.IntTy); 1995 if (MSInheritanceAttr::hasVBTableOffsetField(Inheritance)) 1996 fields.push_back(CGM.IntTy); // VirtualBaseAdjustmentOffset 1997 1998 if (fields.size() == 1) 1999 return fields[0]; 2000 return llvm::StructType::get(CGM.getLLVMContext(), fields); 2001} 2002 2003void MicrosoftCXXABI:: 2004GetNullMemberPointerFields(const MemberPointerType *MPT, 2005 llvm::SmallVectorImpl<llvm::Constant *> &fields) { 2006 assert(fields.empty()); 2007 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl(); 2008 MSInheritanceAttr::Spelling Inheritance = RD->getMSInheritanceModel(); 2009 if (MPT->isMemberFunctionPointer()) { 2010 // FunctionPointerOrVirtualThunk 2011 fields.push_back(llvm::Constant::getNullValue(CGM.VoidPtrTy)); 2012 } else { 2013 if (RD->nullFieldOffsetIsZero()) 2014 fields.push_back(getZeroInt()); // FieldOffset 2015 else 2016 fields.push_back(getAllOnesInt()); // FieldOffset 2017 } 2018 2019 if (MSInheritanceAttr::hasNVOffsetField(MPT->isMemberFunctionPointer(), 2020 Inheritance)) 2021 fields.push_back(getZeroInt()); 2022 if (MSInheritanceAttr::hasVBPtrOffsetField(Inheritance)) 2023 fields.push_back(getZeroInt()); 2024 if (MSInheritanceAttr::hasVBTableOffsetField(Inheritance)) 2025 fields.push_back(getAllOnesInt()); 2026} 2027 2028llvm::Constant * 2029MicrosoftCXXABI::EmitNullMemberPointer(const MemberPointerType *MPT) { 2030 llvm::SmallVector<llvm::Constant *, 4> fields; 2031 GetNullMemberPointerFields(MPT, fields); 2032 if (fields.size() == 1) 2033 return fields[0]; 2034 llvm::Constant *Res = llvm::ConstantStruct::getAnon(fields); 2035 assert(Res->getType() == ConvertMemberPointerType(MPT)); 2036 return Res; 2037} 2038 2039llvm::Constant * 2040MicrosoftCXXABI::EmitFullMemberPointer(llvm::Constant *FirstField, 2041 bool IsMemberFunction, 2042 const CXXRecordDecl *RD, 2043 CharUnits NonVirtualBaseAdjustment) 2044{ 2045 MSInheritanceAttr::Spelling Inheritance = RD->getMSInheritanceModel(); 2046 2047 // Single inheritance class member pointer are represented as scalars instead 2048 // of aggregates. 2049 if (MSInheritanceAttr::hasOnlyOneField(IsMemberFunction, Inheritance)) 2050 return FirstField; 2051 2052 llvm::SmallVector<llvm::Constant *, 4> fields; 2053 fields.push_back(FirstField); 2054 2055 if (MSInheritanceAttr::hasNVOffsetField(IsMemberFunction, Inheritance)) 2056 fields.push_back(llvm::ConstantInt::get( 2057 CGM.IntTy, NonVirtualBaseAdjustment.getQuantity())); 2058 2059 if (MSInheritanceAttr::hasVBPtrOffsetField(Inheritance)) { 2060 CharUnits Offs = CharUnits::Zero(); 2061 if (RD->getNumVBases()) 2062 Offs = getContext().getASTRecordLayout(RD).getVBPtrOffset(); 2063 fields.push_back(llvm::ConstantInt::get(CGM.IntTy, Offs.getQuantity())); 2064 } 2065 2066 // The rest of the fields are adjusted by conversions to a more derived class. 2067 if (MSInheritanceAttr::hasVBTableOffsetField(Inheritance)) 2068 fields.push_back(getZeroInt()); 2069 2070 return llvm::ConstantStruct::getAnon(fields); 2071} 2072 2073llvm::Constant * 2074MicrosoftCXXABI::EmitMemberDataPointer(const MemberPointerType *MPT, 2075 CharUnits offset) { 2076 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl(); 2077 llvm::Constant *FirstField = 2078 llvm::ConstantInt::get(CGM.IntTy, offset.getQuantity()); 2079 return EmitFullMemberPointer(FirstField, /*IsMemberFunction=*/false, RD, 2080 CharUnits::Zero()); 2081} 2082 2083llvm::Constant *MicrosoftCXXABI::EmitMemberPointer(const CXXMethodDecl *MD) { 2084 return BuildMemberPointer(MD->getParent(), MD, CharUnits::Zero()); 2085} 2086 2087llvm::Constant *MicrosoftCXXABI::EmitMemberPointer(const APValue &MP, 2088 QualType MPType) { 2089 const MemberPointerType *MPT = MPType->castAs<MemberPointerType>(); 2090 const ValueDecl *MPD = MP.getMemberPointerDecl(); 2091 if (!MPD) 2092 return EmitNullMemberPointer(MPT); 2093 2094 CharUnits ThisAdjustment = getMemberPointerPathAdjustment(MP); 2095 2096 // FIXME PR15713: Support virtual inheritance paths. 2097 2098 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(MPD)) 2099 return BuildMemberPointer(MPT->getMostRecentCXXRecordDecl(), MD, 2100 ThisAdjustment); 2101 2102 CharUnits FieldOffset = 2103 getContext().toCharUnitsFromBits(getContext().getFieldOffset(MPD)); 2104 return EmitMemberDataPointer(MPT, ThisAdjustment + FieldOffset); 2105} 2106 2107llvm::Constant * 2108MicrosoftCXXABI::BuildMemberPointer(const CXXRecordDecl *RD, 2109 const CXXMethodDecl *MD, 2110 CharUnits NonVirtualBaseAdjustment) { 2111 assert(MD->isInstance() && "Member function must not be static!"); 2112 MD = MD->getCanonicalDecl(); 2113 RD = RD->getMostRecentDecl(); 2114 CodeGenTypes &Types = CGM.getTypes(); 2115 2116 llvm::Constant *FirstField; 2117 const FunctionProtoType *FPT = MD->getType()->castAs<FunctionProtoType>(); 2118 if (!MD->isVirtual()) { 2119 llvm::Type *Ty; 2120 // Check whether the function has a computable LLVM signature. 2121 if (Types.isFuncTypeConvertible(FPT)) { 2122 // The function has a computable LLVM signature; use the correct type. 2123 Ty = Types.GetFunctionType(Types.arrangeCXXMethodDeclaration(MD)); 2124 } else { 2125 // Use an arbitrary non-function type to tell GetAddrOfFunction that the 2126 // function type is incomplete. 2127 Ty = CGM.PtrDiffTy; 2128 } 2129 FirstField = CGM.GetAddrOfFunction(MD, Ty); 2130 FirstField = llvm::ConstantExpr::getBitCast(FirstField, CGM.VoidPtrTy); 2131 } else { 2132 MicrosoftVTableContext::MethodVFTableLocation ML = 2133 CGM.getMicrosoftVTableContext().getMethodVFTableLocation(MD); 2134 if (!CGM.getTypes().isFuncTypeConvertible( 2135 MD->getType()->castAs<FunctionType>())) { 2136 CGM.ErrorUnsupported(MD, "pointer to virtual member function with " 2137 "incomplete return or parameter type"); 2138 FirstField = llvm::Constant::getNullValue(CGM.VoidPtrTy); 2139 } else if (FPT->getCallConv() == CC_X86FastCall) { 2140 CGM.ErrorUnsupported(MD, "pointer to fastcall virtual member function"); 2141 FirstField = llvm::Constant::getNullValue(CGM.VoidPtrTy); 2142 } else if (ML.VBase) { 2143 CGM.ErrorUnsupported(MD, "pointer to virtual member function overriding " 2144 "member function in virtual base class"); 2145 FirstField = llvm::Constant::getNullValue(CGM.VoidPtrTy); 2146 } else { 2147 llvm::Function *Thunk = EmitVirtualMemPtrThunk(MD, ML); 2148 FirstField = llvm::ConstantExpr::getBitCast(Thunk, CGM.VoidPtrTy); 2149 // Include the vfptr adjustment if the method is in a non-primary vftable. 2150 NonVirtualBaseAdjustment += ML.VFPtrOffset; 2151 } 2152 } 2153 2154 // The rest of the fields are common with data member pointers. 2155 return EmitFullMemberPointer(FirstField, /*IsMemberFunction=*/true, RD, 2156 NonVirtualBaseAdjustment); 2157} 2158 2159/// Member pointers are the same if they're either bitwise identical *or* both 2160/// null. Null-ness for function members is determined by the first field, 2161/// while for data member pointers we must compare all fields. 2162llvm::Value * 2163MicrosoftCXXABI::EmitMemberPointerComparison(CodeGenFunction &CGF, 2164 llvm::Value *L, 2165 llvm::Value *R, 2166 const MemberPointerType *MPT, 2167 bool Inequality) { 2168 CGBuilderTy &Builder = CGF.Builder; 2169 2170 // Handle != comparisons by switching the sense of all boolean operations. 2171 llvm::ICmpInst::Predicate Eq; 2172 llvm::Instruction::BinaryOps And, Or; 2173 if (Inequality) { 2174 Eq = llvm::ICmpInst::ICMP_NE; 2175 And = llvm::Instruction::Or; 2176 Or = llvm::Instruction::And; 2177 } else { 2178 Eq = llvm::ICmpInst::ICMP_EQ; 2179 And = llvm::Instruction::And; 2180 Or = llvm::Instruction::Or; 2181 } 2182 2183 // If this is a single field member pointer (single inheritance), this is a 2184 // single icmp. 2185 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl(); 2186 MSInheritanceAttr::Spelling Inheritance = RD->getMSInheritanceModel(); 2187 if (MSInheritanceAttr::hasOnlyOneField(MPT->isMemberFunctionPointer(), 2188 Inheritance)) 2189 return Builder.CreateICmp(Eq, L, R); 2190 2191 // Compare the first field. 2192 llvm::Value *L0 = Builder.CreateExtractValue(L, 0, "lhs.0"); 2193 llvm::Value *R0 = Builder.CreateExtractValue(R, 0, "rhs.0"); 2194 llvm::Value *Cmp0 = Builder.CreateICmp(Eq, L0, R0, "memptr.cmp.first"); 2195 2196 // Compare everything other than the first field. 2197 llvm::Value *Res = nullptr; 2198 llvm::StructType *LType = cast<llvm::StructType>(L->getType()); 2199 for (unsigned I = 1, E = LType->getNumElements(); I != E; ++I) { 2200 llvm::Value *LF = Builder.CreateExtractValue(L, I); 2201 llvm::Value *RF = Builder.CreateExtractValue(R, I); 2202 llvm::Value *Cmp = Builder.CreateICmp(Eq, LF, RF, "memptr.cmp.rest"); 2203 if (Res) 2204 Res = Builder.CreateBinOp(And, Res, Cmp); 2205 else 2206 Res = Cmp; 2207 } 2208 2209 // Check if the first field is 0 if this is a function pointer. 2210 if (MPT->isMemberFunctionPointer()) { 2211 // (l1 == r1 && ...) || l0 == 0 2212 llvm::Value *Zero = llvm::Constant::getNullValue(L0->getType()); 2213 llvm::Value *IsZero = Builder.CreateICmp(Eq, L0, Zero, "memptr.cmp.iszero"); 2214 Res = Builder.CreateBinOp(Or, Res, IsZero); 2215 } 2216 2217 // Combine the comparison of the first field, which must always be true for 2218 // this comparison to succeeed. 2219 return Builder.CreateBinOp(And, Res, Cmp0, "memptr.cmp"); 2220} 2221 2222llvm::Value * 2223MicrosoftCXXABI::EmitMemberPointerIsNotNull(CodeGenFunction &CGF, 2224 llvm::Value *MemPtr, 2225 const MemberPointerType *MPT) { 2226 CGBuilderTy &Builder = CGF.Builder; 2227 llvm::SmallVector<llvm::Constant *, 4> fields; 2228 // We only need one field for member functions. 2229 if (MPT->isMemberFunctionPointer()) 2230 fields.push_back(llvm::Constant::getNullValue(CGM.VoidPtrTy)); 2231 else 2232 GetNullMemberPointerFields(MPT, fields); 2233 assert(!fields.empty()); 2234 llvm::Value *FirstField = MemPtr; 2235 if (MemPtr->getType()->isStructTy()) 2236 FirstField = Builder.CreateExtractValue(MemPtr, 0); 2237 llvm::Value *Res = Builder.CreateICmpNE(FirstField, fields[0], "memptr.cmp0"); 2238 2239 // For function member pointers, we only need to test the function pointer 2240 // field. The other fields if any can be garbage. 2241 if (MPT->isMemberFunctionPointer()) 2242 return Res; 2243 2244 // Otherwise, emit a series of compares and combine the results. 2245 for (int I = 1, E = fields.size(); I < E; ++I) { 2246 llvm::Value *Field = Builder.CreateExtractValue(MemPtr, I); 2247 llvm::Value *Next = Builder.CreateICmpNE(Field, fields[I], "memptr.cmp"); 2248 Res = Builder.CreateOr(Res, Next, "memptr.tobool"); 2249 } 2250 return Res; 2251} 2252 2253bool MicrosoftCXXABI::MemberPointerConstantIsNull(const MemberPointerType *MPT, 2254 llvm::Constant *Val) { 2255 // Function pointers are null if the pointer in the first field is null. 2256 if (MPT->isMemberFunctionPointer()) { 2257 llvm::Constant *FirstField = Val->getType()->isStructTy() ? 2258 Val->getAggregateElement(0U) : Val; 2259 return FirstField->isNullValue(); 2260 } 2261 2262 // If it's not a function pointer and it's zero initializable, we can easily 2263 // check zero. 2264 if (isZeroInitializable(MPT) && Val->isNullValue()) 2265 return true; 2266 2267 // Otherwise, break down all the fields for comparison. Hopefully these 2268 // little Constants are reused, while a big null struct might not be. 2269 llvm::SmallVector<llvm::Constant *, 4> Fields; 2270 GetNullMemberPointerFields(MPT, Fields); 2271 if (Fields.size() == 1) { 2272 assert(Val->getType()->isIntegerTy()); 2273 return Val == Fields[0]; 2274 } 2275 2276 unsigned I, E; 2277 for (I = 0, E = Fields.size(); I != E; ++I) { 2278 if (Val->getAggregateElement(I) != Fields[I]) 2279 break; 2280 } 2281 return I == E; 2282} 2283 2284llvm::Value * 2285MicrosoftCXXABI::GetVBaseOffsetFromVBPtr(CodeGenFunction &CGF, 2286 llvm::Value *This, 2287 llvm::Value *VBPtrOffset, 2288 llvm::Value *VBTableOffset, 2289 llvm::Value **VBPtrOut) { 2290 CGBuilderTy &Builder = CGF.Builder; 2291 // Load the vbtable pointer from the vbptr in the instance. 2292 This = Builder.CreateBitCast(This, CGM.Int8PtrTy); 2293 llvm::Value *VBPtr = 2294 Builder.CreateInBoundsGEP(This, VBPtrOffset, "vbptr"); 2295 if (VBPtrOut) *VBPtrOut = VBPtr; 2296 VBPtr = Builder.CreateBitCast(VBPtr, 2297 CGM.Int32Ty->getPointerTo(0)->getPointerTo(0)); 2298 llvm::Value *VBTable = Builder.CreateLoad(VBPtr, "vbtable"); 2299 2300 // Translate from byte offset to table index. It improves analyzability. 2301 llvm::Value *VBTableIndex = Builder.CreateAShr( 2302 VBTableOffset, llvm::ConstantInt::get(VBTableOffset->getType(), 2), 2303 "vbtindex", /*isExact=*/true); 2304 2305 // Load an i32 offset from the vb-table. 2306 llvm::Value *VBaseOffs = Builder.CreateInBoundsGEP(VBTable, VBTableIndex); 2307 VBaseOffs = Builder.CreateBitCast(VBaseOffs, CGM.Int32Ty->getPointerTo(0)); 2308 return Builder.CreateLoad(VBaseOffs, "vbase_offs"); 2309} 2310 2311// Returns an adjusted base cast to i8*, since we do more address arithmetic on 2312// it. 2313llvm::Value *MicrosoftCXXABI::AdjustVirtualBase( 2314 CodeGenFunction &CGF, const Expr *E, const CXXRecordDecl *RD, 2315 llvm::Value *Base, llvm::Value *VBTableOffset, llvm::Value *VBPtrOffset) { 2316 CGBuilderTy &Builder = CGF.Builder; 2317 Base = Builder.CreateBitCast(Base, CGM.Int8PtrTy); 2318 llvm::BasicBlock *OriginalBB = nullptr; 2319 llvm::BasicBlock *SkipAdjustBB = nullptr; 2320 llvm::BasicBlock *VBaseAdjustBB = nullptr; 2321 2322 // In the unspecified inheritance model, there might not be a vbtable at all, 2323 // in which case we need to skip the virtual base lookup. If there is a 2324 // vbtable, the first entry is a no-op entry that gives back the original 2325 // base, so look for a virtual base adjustment offset of zero. 2326 if (VBPtrOffset) { 2327 OriginalBB = Builder.GetInsertBlock(); 2328 VBaseAdjustBB = CGF.createBasicBlock("memptr.vadjust"); 2329 SkipAdjustBB = CGF.createBasicBlock("memptr.skip_vadjust"); 2330 llvm::Value *IsVirtual = 2331 Builder.CreateICmpNE(VBTableOffset, getZeroInt(), 2332 "memptr.is_vbase"); 2333 Builder.CreateCondBr(IsVirtual, VBaseAdjustBB, SkipAdjustBB); 2334 CGF.EmitBlock(VBaseAdjustBB); 2335 } 2336 2337 // If we weren't given a dynamic vbptr offset, RD should be complete and we'll 2338 // know the vbptr offset. 2339 if (!VBPtrOffset) { 2340 CharUnits offs = CharUnits::Zero(); 2341 if (!RD->hasDefinition()) { 2342 DiagnosticsEngine &Diags = CGF.CGM.getDiags(); 2343 unsigned DiagID = Diags.getCustomDiagID( 2344 DiagnosticsEngine::Error, 2345 "member pointer representation requires a " 2346 "complete class type for %0 to perform this expression"); 2347 Diags.Report(E->getExprLoc(), DiagID) << RD << E->getSourceRange(); 2348 } else if (RD->getNumVBases()) 2349 offs = getContext().getASTRecordLayout(RD).getVBPtrOffset(); 2350 VBPtrOffset = llvm::ConstantInt::get(CGM.IntTy, offs.getQuantity()); 2351 } 2352 llvm::Value *VBPtr = nullptr; 2353 llvm::Value *VBaseOffs = 2354 GetVBaseOffsetFromVBPtr(CGF, Base, VBPtrOffset, VBTableOffset, &VBPtr); 2355 llvm::Value *AdjustedBase = Builder.CreateInBoundsGEP(VBPtr, VBaseOffs); 2356 2357 // Merge control flow with the case where we didn't have to adjust. 2358 if (VBaseAdjustBB) { 2359 Builder.CreateBr(SkipAdjustBB); 2360 CGF.EmitBlock(SkipAdjustBB); 2361 llvm::PHINode *Phi = Builder.CreatePHI(CGM.Int8PtrTy, 2, "memptr.base"); 2362 Phi->addIncoming(Base, OriginalBB); 2363 Phi->addIncoming(AdjustedBase, VBaseAdjustBB); 2364 return Phi; 2365 } 2366 return AdjustedBase; 2367} 2368 2369llvm::Value *MicrosoftCXXABI::EmitMemberDataPointerAddress( 2370 CodeGenFunction &CGF, const Expr *E, llvm::Value *Base, llvm::Value *MemPtr, 2371 const MemberPointerType *MPT) { 2372 assert(MPT->isMemberDataPointer()); 2373 unsigned AS = Base->getType()->getPointerAddressSpace(); 2374 llvm::Type *PType = 2375 CGF.ConvertTypeForMem(MPT->getPointeeType())->getPointerTo(AS); 2376 CGBuilderTy &Builder = CGF.Builder; 2377 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl(); 2378 MSInheritanceAttr::Spelling Inheritance = RD->getMSInheritanceModel(); 2379 2380 // Extract the fields we need, regardless of model. We'll apply them if we 2381 // have them. 2382 llvm::Value *FieldOffset = MemPtr; 2383 llvm::Value *VirtualBaseAdjustmentOffset = nullptr; 2384 llvm::Value *VBPtrOffset = nullptr; 2385 if (MemPtr->getType()->isStructTy()) { 2386 // We need to extract values. 2387 unsigned I = 0; 2388 FieldOffset = Builder.CreateExtractValue(MemPtr, I++); 2389 if (MSInheritanceAttr::hasVBPtrOffsetField(Inheritance)) 2390 VBPtrOffset = Builder.CreateExtractValue(MemPtr, I++); 2391 if (MSInheritanceAttr::hasVBTableOffsetField(Inheritance)) 2392 VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(MemPtr, I++); 2393 } 2394 2395 if (VirtualBaseAdjustmentOffset) { 2396 Base = AdjustVirtualBase(CGF, E, RD, Base, VirtualBaseAdjustmentOffset, 2397 VBPtrOffset); 2398 } 2399 2400 // Cast to char*. 2401 Base = Builder.CreateBitCast(Base, Builder.getInt8Ty()->getPointerTo(AS)); 2402 2403 // Apply the offset, which we assume is non-null. 2404 llvm::Value *Addr = 2405 Builder.CreateInBoundsGEP(Base, FieldOffset, "memptr.offset"); 2406 2407 // Cast the address to the appropriate pointer type, adopting the address 2408 // space of the base pointer. 2409 return Builder.CreateBitCast(Addr, PType); 2410} 2411 2412static MSInheritanceAttr::Spelling 2413getInheritanceFromMemptr(const MemberPointerType *MPT) { 2414 return MPT->getMostRecentCXXRecordDecl()->getMSInheritanceModel(); 2415} 2416 2417llvm::Value * 2418MicrosoftCXXABI::EmitMemberPointerConversion(CodeGenFunction &CGF, 2419 const CastExpr *E, 2420 llvm::Value *Src) { 2421 assert(E->getCastKind() == CK_DerivedToBaseMemberPointer || 2422 E->getCastKind() == CK_BaseToDerivedMemberPointer || 2423 E->getCastKind() == CK_ReinterpretMemberPointer); 2424 2425 // Use constant emission if we can. 2426 if (isa<llvm::Constant>(Src)) 2427 return EmitMemberPointerConversion(E, cast<llvm::Constant>(Src)); 2428 2429 // We may be adding or dropping fields from the member pointer, so we need 2430 // both types and the inheritance models of both records. 2431 const MemberPointerType *SrcTy = 2432 E->getSubExpr()->getType()->castAs<MemberPointerType>(); 2433 const MemberPointerType *DstTy = E->getType()->castAs<MemberPointerType>(); 2434 bool IsFunc = SrcTy->isMemberFunctionPointer(); 2435 2436 // If the classes use the same null representation, reinterpret_cast is a nop. 2437 bool IsReinterpret = E->getCastKind() == CK_ReinterpretMemberPointer; 2438 if (IsReinterpret && IsFunc) 2439 return Src; 2440 2441 CXXRecordDecl *SrcRD = SrcTy->getMostRecentCXXRecordDecl(); 2442 CXXRecordDecl *DstRD = DstTy->getMostRecentCXXRecordDecl(); 2443 if (IsReinterpret && 2444 SrcRD->nullFieldOffsetIsZero() == DstRD->nullFieldOffsetIsZero()) 2445 return Src; 2446 2447 CGBuilderTy &Builder = CGF.Builder; 2448 2449 // Branch past the conversion if Src is null. 2450 llvm::Value *IsNotNull = EmitMemberPointerIsNotNull(CGF, Src, SrcTy); 2451 llvm::Constant *DstNull = EmitNullMemberPointer(DstTy); 2452 2453 // C++ 5.2.10p9: The null member pointer value is converted to the null member 2454 // pointer value of the destination type. 2455 if (IsReinterpret) { 2456 // For reinterpret casts, sema ensures that src and dst are both functions 2457 // or data and have the same size, which means the LLVM types should match. 2458 assert(Src->getType() == DstNull->getType()); 2459 return Builder.CreateSelect(IsNotNull, Src, DstNull); 2460 } 2461 2462 llvm::BasicBlock *OriginalBB = Builder.GetInsertBlock(); 2463 llvm::BasicBlock *ConvertBB = CGF.createBasicBlock("memptr.convert"); 2464 llvm::BasicBlock *ContinueBB = CGF.createBasicBlock("memptr.converted"); 2465 Builder.CreateCondBr(IsNotNull, ConvertBB, ContinueBB); 2466 CGF.EmitBlock(ConvertBB); 2467 2468 // Decompose src. 2469 llvm::Value *FirstField = Src; 2470 llvm::Value *NonVirtualBaseAdjustment = nullptr; 2471 llvm::Value *VirtualBaseAdjustmentOffset = nullptr; 2472 llvm::Value *VBPtrOffset = nullptr; 2473 MSInheritanceAttr::Spelling SrcInheritance = SrcRD->getMSInheritanceModel(); 2474 if (!MSInheritanceAttr::hasOnlyOneField(IsFunc, SrcInheritance)) { 2475 // We need to extract values. 2476 unsigned I = 0; 2477 FirstField = Builder.CreateExtractValue(Src, I++); 2478 if (MSInheritanceAttr::hasNVOffsetField(IsFunc, SrcInheritance)) 2479 NonVirtualBaseAdjustment = Builder.CreateExtractValue(Src, I++); 2480 if (MSInheritanceAttr::hasVBPtrOffsetField(SrcInheritance)) 2481 VBPtrOffset = Builder.CreateExtractValue(Src, I++); 2482 if (MSInheritanceAttr::hasVBTableOffsetField(SrcInheritance)) 2483 VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(Src, I++); 2484 } 2485 2486 // For data pointers, we adjust the field offset directly. For functions, we 2487 // have a separate field. 2488 llvm::Constant *Adj = getMemberPointerAdjustment(E); 2489 if (Adj) { 2490 Adj = llvm::ConstantExpr::getTruncOrBitCast(Adj, CGM.IntTy); 2491 llvm::Value *&NVAdjustField = IsFunc ? NonVirtualBaseAdjustment : FirstField; 2492 bool isDerivedToBase = (E->getCastKind() == CK_DerivedToBaseMemberPointer); 2493 if (!NVAdjustField) // If this field didn't exist in src, it's zero. 2494 NVAdjustField = getZeroInt(); 2495 if (isDerivedToBase) 2496 NVAdjustField = Builder.CreateNSWSub(NVAdjustField, Adj, "adj"); 2497 else 2498 NVAdjustField = Builder.CreateNSWAdd(NVAdjustField, Adj, "adj"); 2499 } 2500 2501 // FIXME PR15713: Support conversions through virtually derived classes. 2502 2503 // Recompose dst from the null struct and the adjusted fields from src. 2504 MSInheritanceAttr::Spelling DstInheritance = DstRD->getMSInheritanceModel(); 2505 llvm::Value *Dst; 2506 if (MSInheritanceAttr::hasOnlyOneField(IsFunc, DstInheritance)) { 2507 Dst = FirstField; 2508 } else { 2509 Dst = llvm::UndefValue::get(DstNull->getType()); 2510 unsigned Idx = 0; 2511 Dst = Builder.CreateInsertValue(Dst, FirstField, Idx++); 2512 if (MSInheritanceAttr::hasNVOffsetField(IsFunc, DstInheritance)) 2513 Dst = Builder.CreateInsertValue( 2514 Dst, getValueOrZeroInt(NonVirtualBaseAdjustment), Idx++); 2515 if (MSInheritanceAttr::hasVBPtrOffsetField(DstInheritance)) 2516 Dst = Builder.CreateInsertValue( 2517 Dst, getValueOrZeroInt(VBPtrOffset), Idx++); 2518 if (MSInheritanceAttr::hasVBTableOffsetField(DstInheritance)) 2519 Dst = Builder.CreateInsertValue( 2520 Dst, getValueOrZeroInt(VirtualBaseAdjustmentOffset), Idx++); 2521 } 2522 Builder.CreateBr(ContinueBB); 2523 2524 // In the continuation, choose between DstNull and Dst. 2525 CGF.EmitBlock(ContinueBB); 2526 llvm::PHINode *Phi = Builder.CreatePHI(DstNull->getType(), 2, "memptr.converted"); 2527 Phi->addIncoming(DstNull, OriginalBB); 2528 Phi->addIncoming(Dst, ConvertBB); 2529 return Phi; 2530} 2531 2532llvm::Constant * 2533MicrosoftCXXABI::EmitMemberPointerConversion(const CastExpr *E, 2534 llvm::Constant *Src) { 2535 const MemberPointerType *SrcTy = 2536 E->getSubExpr()->getType()->castAs<MemberPointerType>(); 2537 const MemberPointerType *DstTy = E->getType()->castAs<MemberPointerType>(); 2538 2539 // If src is null, emit a new null for dst. We can't return src because dst 2540 // might have a new representation. 2541 if (MemberPointerConstantIsNull(SrcTy, Src)) 2542 return EmitNullMemberPointer(DstTy); 2543 2544 // We don't need to do anything for reinterpret_casts of non-null member 2545 // pointers. We should only get here when the two type representations have 2546 // the same size. 2547 if (E->getCastKind() == CK_ReinterpretMemberPointer) 2548 return Src; 2549 2550 MSInheritanceAttr::Spelling SrcInheritance = getInheritanceFromMemptr(SrcTy); 2551 MSInheritanceAttr::Spelling DstInheritance = getInheritanceFromMemptr(DstTy); 2552 2553 // Decompose src. 2554 llvm::Constant *FirstField = Src; 2555 llvm::Constant *NonVirtualBaseAdjustment = nullptr; 2556 llvm::Constant *VirtualBaseAdjustmentOffset = nullptr; 2557 llvm::Constant *VBPtrOffset = nullptr; 2558 bool IsFunc = SrcTy->isMemberFunctionPointer(); 2559 if (!MSInheritanceAttr::hasOnlyOneField(IsFunc, SrcInheritance)) { 2560 // We need to extract values. 2561 unsigned I = 0; 2562 FirstField = Src->getAggregateElement(I++); 2563 if (MSInheritanceAttr::hasNVOffsetField(IsFunc, SrcInheritance)) 2564 NonVirtualBaseAdjustment = Src->getAggregateElement(I++); 2565 if (MSInheritanceAttr::hasVBPtrOffsetField(SrcInheritance)) 2566 VBPtrOffset = Src->getAggregateElement(I++); 2567 if (MSInheritanceAttr::hasVBTableOffsetField(SrcInheritance)) 2568 VirtualBaseAdjustmentOffset = Src->getAggregateElement(I++); 2569 } 2570 2571 // For data pointers, we adjust the field offset directly. For functions, we 2572 // have a separate field. 2573 llvm::Constant *Adj = getMemberPointerAdjustment(E); 2574 if (Adj) { 2575 Adj = llvm::ConstantExpr::getTruncOrBitCast(Adj, CGM.IntTy); 2576 llvm::Constant *&NVAdjustField = 2577 IsFunc ? NonVirtualBaseAdjustment : FirstField; 2578 bool IsDerivedToBase = (E->getCastKind() == CK_DerivedToBaseMemberPointer); 2579 if (!NVAdjustField) // If this field didn't exist in src, it's zero. 2580 NVAdjustField = getZeroInt(); 2581 if (IsDerivedToBase) 2582 NVAdjustField = llvm::ConstantExpr::getNSWSub(NVAdjustField, Adj); 2583 else 2584 NVAdjustField = llvm::ConstantExpr::getNSWAdd(NVAdjustField, Adj); 2585 } 2586 2587 // FIXME PR15713: Support conversions through virtually derived classes. 2588 2589 // Recompose dst from the null struct and the adjusted fields from src. 2590 if (MSInheritanceAttr::hasOnlyOneField(IsFunc, DstInheritance)) 2591 return FirstField; 2592 2593 llvm::SmallVector<llvm::Constant *, 4> Fields; 2594 Fields.push_back(FirstField); 2595 if (MSInheritanceAttr::hasNVOffsetField(IsFunc, DstInheritance)) 2596 Fields.push_back(getConstantOrZeroInt(NonVirtualBaseAdjustment)); 2597 if (MSInheritanceAttr::hasVBPtrOffsetField(DstInheritance)) 2598 Fields.push_back(getConstantOrZeroInt(VBPtrOffset)); 2599 if (MSInheritanceAttr::hasVBTableOffsetField(DstInheritance)) 2600 Fields.push_back(getConstantOrZeroInt(VirtualBaseAdjustmentOffset)); 2601 return llvm::ConstantStruct::getAnon(Fields); 2602} 2603 2604llvm::Value *MicrosoftCXXABI::EmitLoadOfMemberFunctionPointer( 2605 CodeGenFunction &CGF, const Expr *E, llvm::Value *&This, 2606 llvm::Value *MemPtr, const MemberPointerType *MPT) { 2607 assert(MPT->isMemberFunctionPointer()); 2608 const FunctionProtoType *FPT = 2609 MPT->getPointeeType()->castAs<FunctionProtoType>(); 2610 const CXXRecordDecl *RD = MPT->getMostRecentCXXRecordDecl(); 2611 llvm::FunctionType *FTy = 2612 CGM.getTypes().GetFunctionType( 2613 CGM.getTypes().arrangeCXXMethodType(RD, FPT)); 2614 CGBuilderTy &Builder = CGF.Builder; 2615 2616 MSInheritanceAttr::Spelling Inheritance = RD->getMSInheritanceModel(); 2617 2618 // Extract the fields we need, regardless of model. We'll apply them if we 2619 // have them. 2620 llvm::Value *FunctionPointer = MemPtr; 2621 llvm::Value *NonVirtualBaseAdjustment = nullptr; 2622 llvm::Value *VirtualBaseAdjustmentOffset = nullptr; 2623 llvm::Value *VBPtrOffset = nullptr; 2624 if (MemPtr->getType()->isStructTy()) { 2625 // We need to extract values. 2626 unsigned I = 0; 2627 FunctionPointer = Builder.CreateExtractValue(MemPtr, I++); 2628 if (MSInheritanceAttr::hasNVOffsetField(MPT, Inheritance)) 2629 NonVirtualBaseAdjustment = Builder.CreateExtractValue(MemPtr, I++); 2630 if (MSInheritanceAttr::hasVBPtrOffsetField(Inheritance)) 2631 VBPtrOffset = Builder.CreateExtractValue(MemPtr, I++); 2632 if (MSInheritanceAttr::hasVBTableOffsetField(Inheritance)) 2633 VirtualBaseAdjustmentOffset = Builder.CreateExtractValue(MemPtr, I++); 2634 } 2635 2636 if (VirtualBaseAdjustmentOffset) { 2637 This = AdjustVirtualBase(CGF, E, RD, This, VirtualBaseAdjustmentOffset, 2638 VBPtrOffset); 2639 } 2640 2641 if (NonVirtualBaseAdjustment) { 2642 // Apply the adjustment and cast back to the original struct type. 2643 llvm::Value *Ptr = Builder.CreateBitCast(This, Builder.getInt8PtrTy()); 2644 Ptr = Builder.CreateInBoundsGEP(Ptr, NonVirtualBaseAdjustment); 2645 This = Builder.CreateBitCast(Ptr, This->getType(), "this.adjusted"); 2646 } 2647 2648 return Builder.CreateBitCast(FunctionPointer, FTy->getPointerTo()); 2649} 2650 2651CGCXXABI *clang::CodeGen::CreateMicrosoftCXXABI(CodeGenModule &CGM) { 2652 return new MicrosoftCXXABI(CGM); 2653} 2654 2655// MS RTTI Overview: 2656// The run time type information emitted by cl.exe contains 5 distinct types of 2657// structures. Many of them reference each other. 2658// 2659// TypeInfo: Static classes that are returned by typeid. 2660// 2661// CompleteObjectLocator: Referenced by vftables. They contain information 2662// required for dynamic casting, including OffsetFromTop. They also contain 2663// a reference to the TypeInfo for the type and a reference to the 2664// CompleteHierarchyDescriptor for the type. 2665// 2666// ClassHieararchyDescriptor: Contains information about a class hierarchy. 2667// Used during dynamic_cast to walk a class hierarchy. References a base 2668// class array and the size of said array. 2669// 2670// BaseClassArray: Contains a list of classes in a hierarchy. BaseClassArray is 2671// somewhat of a misnomer because the most derived class is also in the list 2672// as well as multiple copies of virtual bases (if they occur multiple times 2673// in the hiearchy.) The BaseClassArray contains one BaseClassDescriptor for 2674// every path in the hierarchy, in pre-order depth first order. Note, we do 2675// not declare a specific llvm type for BaseClassArray, it's merely an array 2676// of BaseClassDescriptor pointers. 2677// 2678// BaseClassDescriptor: Contains information about a class in a class hierarchy. 2679// BaseClassDescriptor is also somewhat of a misnomer for the same reason that 2680// BaseClassArray is. It contains information about a class within a 2681// hierarchy such as: is this base is ambiguous and what is its offset in the 2682// vbtable. The names of the BaseClassDescriptors have all of their fields 2683// mangled into them so they can be aggressively deduplicated by the linker. 2684 2685static llvm::GlobalVariable *getTypeInfoVTable(CodeGenModule &CGM) { 2686 StringRef MangledName("\01??_7type_info@@6B@"); 2687 if (auto VTable = CGM.getModule().getNamedGlobal(MangledName)) 2688 return VTable; 2689 return new llvm::GlobalVariable(CGM.getModule(), CGM.Int8PtrTy, 2690 /*Constant=*/true, 2691 llvm::GlobalVariable::ExternalLinkage, 2692 /*Initializer=*/nullptr, MangledName); 2693} 2694 2695namespace { 2696 2697/// \brief A Helper struct that stores information about a class in a class 2698/// hierarchy. The information stored in these structs struct is used during 2699/// the generation of ClassHierarchyDescriptors and BaseClassDescriptors. 2700// During RTTI creation, MSRTTIClasses are stored in a contiguous array with 2701// implicit depth first pre-order tree connectivity. getFirstChild and 2702// getNextSibling allow us to walk the tree efficiently. 2703struct MSRTTIClass { 2704 enum { 2705 IsPrivateOnPath = 1 | 8, 2706 IsAmbiguous = 2, 2707 IsPrivate = 4, 2708 IsVirtual = 16, 2709 HasHierarchyDescriptor = 64 2710 }; 2711 MSRTTIClass(const CXXRecordDecl *RD) : RD(RD) {} 2712 uint32_t initialize(const MSRTTIClass *Parent, 2713 const CXXBaseSpecifier *Specifier); 2714 2715 MSRTTIClass *getFirstChild() { return this + 1; } 2716 static MSRTTIClass *getNextChild(MSRTTIClass *Child) { 2717 return Child + 1 + Child->NumBases; 2718 } 2719 2720 const CXXRecordDecl *RD, *VirtualRoot; 2721 uint32_t Flags, NumBases, OffsetInVBase; 2722}; 2723 2724/// \brief Recursively initialize the base class array. 2725uint32_t MSRTTIClass::initialize(const MSRTTIClass *Parent, 2726 const CXXBaseSpecifier *Specifier) { 2727 Flags = HasHierarchyDescriptor; 2728 if (!Parent) { 2729 VirtualRoot = nullptr; 2730 OffsetInVBase = 0; 2731 } else { 2732 if (Specifier->getAccessSpecifier() != AS_public) 2733 Flags |= IsPrivate | IsPrivateOnPath; 2734 if (Specifier->isVirtual()) { 2735 Flags |= IsVirtual; 2736 VirtualRoot = RD; 2737 OffsetInVBase = 0; 2738 } else { 2739 if (Parent->Flags & IsPrivateOnPath) 2740 Flags |= IsPrivateOnPath; 2741 VirtualRoot = Parent->VirtualRoot; 2742 OffsetInVBase = Parent->OffsetInVBase + RD->getASTContext() 2743 .getASTRecordLayout(Parent->RD).getBaseClassOffset(RD).getQuantity(); 2744 } 2745 } 2746 NumBases = 0; 2747 MSRTTIClass *Child = getFirstChild(); 2748 for (const CXXBaseSpecifier &Base : RD->bases()) { 2749 NumBases += Child->initialize(this, &Base) + 1; 2750 Child = getNextChild(Child); 2751 } 2752 return NumBases; 2753} 2754 2755static llvm::GlobalValue::LinkageTypes getLinkageForRTTI(QualType Ty) { 2756 switch (Ty->getLinkage()) { 2757 case NoLinkage: 2758 case InternalLinkage: 2759 case UniqueExternalLinkage: 2760 return llvm::GlobalValue::InternalLinkage; 2761 2762 case VisibleNoLinkage: 2763 case ExternalLinkage: 2764 return llvm::GlobalValue::LinkOnceODRLinkage; 2765 } 2766 llvm_unreachable("Invalid linkage!"); 2767} 2768 2769/// \brief An ephemeral helper class for building MS RTTI types. It caches some 2770/// calls to the module and information about the most derived class in a 2771/// hierarchy. 2772struct MSRTTIBuilder { 2773 enum { 2774 HasBranchingHierarchy = 1, 2775 HasVirtualBranchingHierarchy = 2, 2776 HasAmbiguousBases = 4 2777 }; 2778 2779 MSRTTIBuilder(MicrosoftCXXABI &ABI, const CXXRecordDecl *RD) 2780 : CGM(ABI.CGM), Context(CGM.getContext()), 2781 VMContext(CGM.getLLVMContext()), Module(CGM.getModule()), RD(RD), 2782 Linkage(getLinkageForRTTI(CGM.getContext().getTagDeclType(RD))), 2783 ABI(ABI) {} 2784 2785 llvm::GlobalVariable *getBaseClassDescriptor(const MSRTTIClass &Classes); 2786 llvm::GlobalVariable * 2787 getBaseClassArray(SmallVectorImpl<MSRTTIClass> &Classes); 2788 llvm::GlobalVariable *getClassHierarchyDescriptor(); 2789 llvm::GlobalVariable *getCompleteObjectLocator(const VPtrInfo *Info); 2790 2791 CodeGenModule &CGM; 2792 ASTContext &Context; 2793 llvm::LLVMContext &VMContext; 2794 llvm::Module &Module; 2795 const CXXRecordDecl *RD; 2796 llvm::GlobalVariable::LinkageTypes Linkage; 2797 MicrosoftCXXABI &ABI; 2798}; 2799 2800} // namespace 2801 2802/// \brief Recursively serializes a class hierarchy in pre-order depth first 2803/// order. 2804static void serializeClassHierarchy(SmallVectorImpl<MSRTTIClass> &Classes, 2805 const CXXRecordDecl *RD) { 2806 Classes.push_back(MSRTTIClass(RD)); 2807 for (const CXXBaseSpecifier &Base : RD->bases()) 2808 serializeClassHierarchy(Classes, Base.getType()->getAsCXXRecordDecl()); 2809} 2810 2811/// \brief Find ambiguity among base classes. 2812static void 2813detectAmbiguousBases(SmallVectorImpl<MSRTTIClass> &Classes) { 2814 llvm::SmallPtrSet<const CXXRecordDecl *, 8> VirtualBases; 2815 llvm::SmallPtrSet<const CXXRecordDecl *, 8> UniqueBases; 2816 llvm::SmallPtrSet<const CXXRecordDecl *, 8> AmbiguousBases; 2817 for (MSRTTIClass *Class = &Classes.front(); Class <= &Classes.back();) { 2818 if ((Class->Flags & MSRTTIClass::IsVirtual) && 2819 !VirtualBases.insert(Class->RD).second) { 2820 Class = MSRTTIClass::getNextChild(Class); 2821 continue; 2822 } 2823 if (!UniqueBases.insert(Class->RD).second) 2824 AmbiguousBases.insert(Class->RD); 2825 Class++; 2826 } 2827 if (AmbiguousBases.empty()) 2828 return; 2829 for (MSRTTIClass &Class : Classes) 2830 if (AmbiguousBases.count(Class.RD)) 2831 Class.Flags |= MSRTTIClass::IsAmbiguous; 2832} 2833 2834llvm::GlobalVariable *MSRTTIBuilder::getClassHierarchyDescriptor() { 2835 SmallString<256> MangledName; 2836 { 2837 llvm::raw_svector_ostream Out(MangledName); 2838 ABI.getMangleContext().mangleCXXRTTIClassHierarchyDescriptor(RD, Out); 2839 } 2840 2841 // Check to see if we've already declared this ClassHierarchyDescriptor. 2842 if (auto CHD = Module.getNamedGlobal(MangledName)) 2843 return CHD; 2844 2845 // Serialize the class hierarchy and initialize the CHD Fields. 2846 SmallVector<MSRTTIClass, 8> Classes; 2847 serializeClassHierarchy(Classes, RD); 2848 Classes.front().initialize(/*Parent=*/nullptr, /*Specifier=*/nullptr); 2849 detectAmbiguousBases(Classes); 2850 int Flags = 0; 2851 for (auto Class : Classes) { 2852 if (Class.RD->getNumBases() > 1) 2853 Flags |= HasBranchingHierarchy; 2854 // Note: cl.exe does not calculate "HasAmbiguousBases" correctly. We 2855 // believe the field isn't actually used. 2856 if (Class.Flags & MSRTTIClass::IsAmbiguous) 2857 Flags |= HasAmbiguousBases; 2858 } 2859 if ((Flags & HasBranchingHierarchy) && RD->getNumVBases() != 0) 2860 Flags |= HasVirtualBranchingHierarchy; 2861 // These gep indices are used to get the address of the first element of the 2862 // base class array. 2863 llvm::Value *GEPIndices[] = {llvm::ConstantInt::get(CGM.IntTy, 0), 2864 llvm::ConstantInt::get(CGM.IntTy, 0)}; 2865 2866 // Forward-declare the class hierarchy descriptor 2867 auto Type = ABI.getClassHierarchyDescriptorType(); 2868 auto CHD = new llvm::GlobalVariable(Module, Type, /*Constant=*/true, Linkage, 2869 /*Initializer=*/nullptr, 2870 MangledName.c_str()); 2871 2872 // Initialize the base class ClassHierarchyDescriptor. 2873 llvm::Constant *Fields[] = { 2874 llvm::ConstantInt::get(CGM.IntTy, 0), // Unknown 2875 llvm::ConstantInt::get(CGM.IntTy, Flags), 2876 llvm::ConstantInt::get(CGM.IntTy, Classes.size()), 2877 ABI.getImageRelativeConstant(llvm::ConstantExpr::getInBoundsGetElementPtr( 2878 getBaseClassArray(Classes), 2879 llvm::ArrayRef<llvm::Value *>(GEPIndices))), 2880 }; 2881 CHD->setInitializer(llvm::ConstantStruct::get(Type, Fields)); 2882 return CHD; 2883} 2884 2885llvm::GlobalVariable * 2886MSRTTIBuilder::getBaseClassArray(SmallVectorImpl<MSRTTIClass> &Classes) { 2887 SmallString<256> MangledName; 2888 { 2889 llvm::raw_svector_ostream Out(MangledName); 2890 ABI.getMangleContext().mangleCXXRTTIBaseClassArray(RD, Out); 2891 } 2892 2893 // Forward-declare the base class array. 2894 // cl.exe pads the base class array with 1 (in 32 bit mode) or 4 (in 64 bit 2895 // mode) bytes of padding. We provide a pointer sized amount of padding by 2896 // adding +1 to Classes.size(). The sections have pointer alignment and are 2897 // marked pick-any so it shouldn't matter. 2898 llvm::Type *PtrType = ABI.getImageRelativeType( 2899 ABI.getBaseClassDescriptorType()->getPointerTo()); 2900 auto *ArrType = llvm::ArrayType::get(PtrType, Classes.size() + 1); 2901 auto *BCA = new llvm::GlobalVariable( 2902 Module, ArrType, 2903 /*Constant=*/true, Linkage, /*Initializer=*/nullptr, MangledName.c_str()); 2904 2905 // Initialize the BaseClassArray. 2906 SmallVector<llvm::Constant *, 8> BaseClassArrayData; 2907 for (MSRTTIClass &Class : Classes) 2908 BaseClassArrayData.push_back( 2909 ABI.getImageRelativeConstant(getBaseClassDescriptor(Class))); 2910 BaseClassArrayData.push_back(llvm::Constant::getNullValue(PtrType)); 2911 BCA->setInitializer(llvm::ConstantArray::get(ArrType, BaseClassArrayData)); 2912 return BCA; 2913} 2914 2915llvm::GlobalVariable * 2916MSRTTIBuilder::getBaseClassDescriptor(const MSRTTIClass &Class) { 2917 // Compute the fields for the BaseClassDescriptor. They are computed up front 2918 // because they are mangled into the name of the object. 2919 uint32_t OffsetInVBTable = 0; 2920 int32_t VBPtrOffset = -1; 2921 if (Class.VirtualRoot) { 2922 auto &VTableContext = CGM.getMicrosoftVTableContext(); 2923 OffsetInVBTable = VTableContext.getVBTableIndex(RD, Class.VirtualRoot) * 4; 2924 VBPtrOffset = Context.getASTRecordLayout(RD).getVBPtrOffset().getQuantity(); 2925 } 2926 2927 SmallString<256> MangledName; 2928 { 2929 llvm::raw_svector_ostream Out(MangledName); 2930 ABI.getMangleContext().mangleCXXRTTIBaseClassDescriptor( 2931 Class.RD, Class.OffsetInVBase, VBPtrOffset, OffsetInVBTable, 2932 Class.Flags, Out); 2933 } 2934 2935 // Check to see if we've already declared this object. 2936 if (auto BCD = Module.getNamedGlobal(MangledName)) 2937 return BCD; 2938 2939 // Forward-declare the base class descriptor. 2940 auto Type = ABI.getBaseClassDescriptorType(); 2941 auto BCD = new llvm::GlobalVariable(Module, Type, /*Constant=*/true, Linkage, 2942 /*Initializer=*/nullptr, 2943 MangledName.c_str()); 2944 2945 // Initialize the BaseClassDescriptor. 2946 llvm::Constant *Fields[] = { 2947 ABI.getImageRelativeConstant( 2948 ABI.getAddrOfRTTIDescriptor(Context.getTypeDeclType(Class.RD))), 2949 llvm::ConstantInt::get(CGM.IntTy, Class.NumBases), 2950 llvm::ConstantInt::get(CGM.IntTy, Class.OffsetInVBase), 2951 llvm::ConstantInt::get(CGM.IntTy, VBPtrOffset), 2952 llvm::ConstantInt::get(CGM.IntTy, OffsetInVBTable), 2953 llvm::ConstantInt::get(CGM.IntTy, Class.Flags), 2954 ABI.getImageRelativeConstant( 2955 MSRTTIBuilder(ABI, Class.RD).getClassHierarchyDescriptor()), 2956 }; 2957 BCD->setInitializer(llvm::ConstantStruct::get(Type, Fields)); 2958 return BCD; 2959} 2960 2961llvm::GlobalVariable * 2962MSRTTIBuilder::getCompleteObjectLocator(const VPtrInfo *Info) { 2963 SmallString<256> MangledName; 2964 { 2965 llvm::raw_svector_ostream Out(MangledName); 2966 ABI.getMangleContext().mangleCXXRTTICompleteObjectLocator(RD, Info->MangledPath, Out); 2967 } 2968 2969 // Check to see if we've already computed this complete object locator. 2970 if (auto COL = Module.getNamedGlobal(MangledName)) 2971 return COL; 2972 2973 // Compute the fields of the complete object locator. 2974 int OffsetToTop = Info->FullOffsetInMDC.getQuantity(); 2975 int VFPtrOffset = 0; 2976 // The offset includes the vtordisp if one exists. 2977 if (const CXXRecordDecl *VBase = Info->getVBaseWithVPtr()) 2978 if (Context.getASTRecordLayout(RD) 2979 .getVBaseOffsetsMap() 2980 .find(VBase) 2981 ->second.hasVtorDisp()) 2982 VFPtrOffset = Info->NonVirtualOffset.getQuantity() + 4; 2983 2984 // Forward-declare the complete object locator. 2985 llvm::StructType *Type = ABI.getCompleteObjectLocatorType(); 2986 auto COL = new llvm::GlobalVariable(Module, Type, /*Constant=*/true, Linkage, 2987 /*Initializer=*/nullptr, MangledName.c_str()); 2988 2989 // Initialize the CompleteObjectLocator. 2990 llvm::Constant *Fields[] = { 2991 llvm::ConstantInt::get(CGM.IntTy, ABI.isImageRelative()), 2992 llvm::ConstantInt::get(CGM.IntTy, OffsetToTop), 2993 llvm::ConstantInt::get(CGM.IntTy, VFPtrOffset), 2994 ABI.getImageRelativeConstant( 2995 CGM.GetAddrOfRTTIDescriptor(Context.getTypeDeclType(RD))), 2996 ABI.getImageRelativeConstant(getClassHierarchyDescriptor()), 2997 ABI.getImageRelativeConstant(COL), 2998 }; 2999 llvm::ArrayRef<llvm::Constant *> FieldsRef(Fields); 3000 if (!ABI.isImageRelative()) 3001 FieldsRef = FieldsRef.drop_back(); 3002 COL->setInitializer(llvm::ConstantStruct::get(Type, FieldsRef)); 3003 return COL; 3004} 3005 3006/// \brief Gets a TypeDescriptor. Returns a llvm::Constant * rather than a 3007/// llvm::GlobalVariable * because different type descriptors have different 3008/// types, and need to be abstracted. They are abstracting by casting the 3009/// address to an Int8PtrTy. 3010llvm::Constant *MicrosoftCXXABI::getAddrOfRTTIDescriptor(QualType Type) { 3011 SmallString<256> MangledName, TypeInfoString; 3012 { 3013 llvm::raw_svector_ostream Out(MangledName); 3014 getMangleContext().mangleCXXRTTI(Type, Out); 3015 } 3016 3017 // Check to see if we've already declared this TypeDescriptor. 3018 if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName)) 3019 return llvm::ConstantExpr::getBitCast(GV, CGM.Int8PtrTy); 3020 3021 // Compute the fields for the TypeDescriptor. 3022 { 3023 llvm::raw_svector_ostream Out(TypeInfoString); 3024 getMangleContext().mangleCXXRTTIName(Type, Out); 3025 } 3026 3027 // Declare and initialize the TypeDescriptor. 3028 llvm::Constant *Fields[] = { 3029 getTypeInfoVTable(CGM), // VFPtr 3030 llvm::ConstantPointerNull::get(CGM.Int8PtrTy), // Runtime data 3031 llvm::ConstantDataArray::getString(CGM.getLLVMContext(), TypeInfoString)}; 3032 llvm::StructType *TypeDescriptorType = 3033 getTypeDescriptorType(TypeInfoString); 3034 return llvm::ConstantExpr::getBitCast( 3035 new llvm::GlobalVariable( 3036 CGM.getModule(), TypeDescriptorType, /*Constant=*/false, 3037 getLinkageForRTTI(Type), 3038 llvm::ConstantStruct::get(TypeDescriptorType, Fields), 3039 MangledName.c_str()), 3040 CGM.Int8PtrTy); 3041} 3042 3043/// \brief Gets or a creates a Microsoft CompleteObjectLocator. 3044llvm::GlobalVariable * 3045MicrosoftCXXABI::getMSCompleteObjectLocator(const CXXRecordDecl *RD, 3046 const VPtrInfo *Info) { 3047 return MSRTTIBuilder(*this, RD).getCompleteObjectLocator(Info); 3048} 3049 3050static void emitCXXConstructor(CodeGenModule &CGM, 3051 const CXXConstructorDecl *ctor, 3052 StructorType ctorType) { 3053 // There are no constructor variants, always emit the complete destructor. 3054 CGM.codegenCXXStructor(ctor, StructorType::Complete); 3055} 3056 3057static void emitCXXDestructor(CodeGenModule &CGM, const CXXDestructorDecl *dtor, 3058 StructorType dtorType) { 3059 // The complete destructor is equivalent to the base destructor for 3060 // classes with no virtual bases, so try to emit it as an alias. 3061 if (!dtor->getParent()->getNumVBases() && 3062 (dtorType == StructorType::Complete || dtorType == StructorType::Base)) { 3063 bool ProducedAlias = !CGM.TryEmitDefinitionAsAlias( 3064 GlobalDecl(dtor, Dtor_Complete), GlobalDecl(dtor, Dtor_Base), true); 3065 if (ProducedAlias) { 3066 if (dtorType == StructorType::Complete) 3067 return; 3068 if (dtor->isVirtual()) 3069 CGM.getVTables().EmitThunks(GlobalDecl(dtor, Dtor_Complete)); 3070 } 3071 } 3072 3073 // The base destructor is equivalent to the base destructor of its 3074 // base class if there is exactly one non-virtual base class with a 3075 // non-trivial destructor, there are no fields with a non-trivial 3076 // destructor, and the body of the destructor is trivial. 3077 if (dtorType == StructorType::Base && !CGM.TryEmitBaseDestructorAsAlias(dtor)) 3078 return; 3079 3080 CGM.codegenCXXStructor(dtor, dtorType); 3081} 3082 3083void MicrosoftCXXABI::emitCXXStructor(const CXXMethodDecl *MD, 3084 StructorType Type) { 3085 if (auto *CD = dyn_cast<CXXConstructorDecl>(MD)) { 3086 emitCXXConstructor(CGM, CD, Type); 3087 return; 3088 } 3089 emitCXXDestructor(CGM, cast<CXXDestructorDecl>(MD), Type); 3090} 3091