CGVTables.cpp revision 82abeaed0b565e819407b523ed73aa5a4185b27f
1//===--- CGVTables.cpp - Emit LLVM Code for C++ vtables -------------------===// 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 contains code dealing with C++ code generation of virtual tables. 11// 12//===----------------------------------------------------------------------===// 13 14#include "CodeGenModule.h" 15#include "CodeGenFunction.h" 16#include "CGCXXABI.h" 17#include "clang/AST/CXXInheritance.h" 18#include "clang/AST/RecordLayout.h" 19#include "clang/Frontend/CodeGenOptions.h" 20#include "llvm/ADT/DenseSet.h" 21#include "llvm/ADT/SetVector.h" 22#include "llvm/Support/Compiler.h" 23#include "llvm/Support/Format.h" 24#include <algorithm> 25#include <cstdio> 26 27using namespace clang; 28using namespace CodeGen; 29 30namespace { 31 32/// BaseOffset - Represents an offset from a derived class to a direct or 33/// indirect base class. 34struct BaseOffset { 35 /// DerivedClass - The derived class. 36 const CXXRecordDecl *DerivedClass; 37 38 /// VirtualBase - If the path from the derived class to the base class 39 /// involves a virtual base class, this holds its declaration. 40 const CXXRecordDecl *VirtualBase; 41 42 /// NonVirtualOffset - The offset from the derived class to the base class. 43 /// (Or the offset from the virtual base class to the base class, if the 44 /// path from the derived class to the base class involves a virtual base 45 /// class. 46 int64_t NonVirtualOffset; 47 48 BaseOffset() : DerivedClass(0), VirtualBase(0), NonVirtualOffset(0) { } 49 BaseOffset(const CXXRecordDecl *DerivedClass, 50 const CXXRecordDecl *VirtualBase, int64_t NonVirtualOffset) 51 : DerivedClass(DerivedClass), VirtualBase(VirtualBase), 52 NonVirtualOffset(NonVirtualOffset) { } 53 54 bool isEmpty() const { return !NonVirtualOffset && !VirtualBase; } 55}; 56 57/// FinalOverriders - Contains the final overrider member functions for all 58/// member functions in the base subobjects of a class. 59class FinalOverriders { 60public: 61 /// OverriderInfo - Information about a final overrider. 62 struct OverriderInfo { 63 /// Method - The method decl of the overrider. 64 const CXXMethodDecl *Method; 65 66 /// Offset - the base offset of the overrider in the layout class. 67 CharUnits Offset; 68 69 OverriderInfo() : Method(0), Offset(CharUnits::Zero()) { } 70 }; 71 72private: 73 /// MostDerivedClass - The most derived class for which the final overriders 74 /// are stored. 75 const CXXRecordDecl *MostDerivedClass; 76 77 /// MostDerivedClassOffset - If we're building final overriders for a 78 /// construction vtable, this holds the offset from the layout class to the 79 /// most derived class. 80 const uint64_t MostDerivedClassOffset; 81 82 /// LayoutClass - The class we're using for layout information. Will be 83 /// different than the most derived class if the final overriders are for a 84 /// construction vtable. 85 const CXXRecordDecl *LayoutClass; 86 87 ASTContext &Context; 88 89 /// MostDerivedClassLayout - the AST record layout of the most derived class. 90 const ASTRecordLayout &MostDerivedClassLayout; 91 92 /// MethodBaseOffsetPairTy - Uniquely identifies a member function 93 /// in a base subobject. 94 typedef std::pair<const CXXMethodDecl *, CharUnits> MethodBaseOffsetPairTy; 95 96 typedef llvm::DenseMap<MethodBaseOffsetPairTy, 97 OverriderInfo> OverridersMapTy; 98 99 /// OverridersMap - The final overriders for all virtual member functions of 100 /// all the base subobjects of the most derived class. 101 OverridersMapTy OverridersMap; 102 103 /// SubobjectsToOffsetsMapTy - A mapping from a base subobject (represented 104 /// as a record decl and a subobject number) and its offsets in the most 105 /// derived class as well as the layout class. 106 typedef llvm::DenseMap<std::pair<const CXXRecordDecl *, unsigned>, 107 CharUnits> SubobjectOffsetMapTy; 108 109 typedef llvm::DenseMap<const CXXRecordDecl *, unsigned> SubobjectCountMapTy; 110 111 /// ComputeBaseOffsets - Compute the offsets for all base subobjects of the 112 /// given base. 113 void ComputeBaseOffsets(BaseSubobject Base, bool IsVirtual, 114 CharUnits OffsetInLayoutClass, 115 SubobjectOffsetMapTy &SubobjectOffsets, 116 SubobjectOffsetMapTy &SubobjectLayoutClassOffsets, 117 SubobjectCountMapTy &SubobjectCounts); 118 119 typedef llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBasesSetTy; 120 121 /// dump - dump the final overriders for a base subobject, and all its direct 122 /// and indirect base subobjects. 123 void dump(llvm::raw_ostream &Out, BaseSubobject Base, 124 VisitedVirtualBasesSetTy& VisitedVirtualBases); 125 126public: 127 FinalOverriders(const CXXRecordDecl *MostDerivedClass, 128 uint64_t MostDerivedClassOffset, 129 const CXXRecordDecl *LayoutClass); 130 131 /// getOverrider - Get the final overrider for the given method declaration in 132 /// the subobject with the given base offset. 133 OverriderInfo getOverrider(const CXXMethodDecl *MD, 134 CharUnits BaseOffset) const { 135 assert(OverridersMap.count(std::make_pair(MD, BaseOffset)) && 136 "Did not find overrider!"); 137 138 return OverridersMap.lookup(std::make_pair(MD, BaseOffset)); 139 } 140 141 /// dump - dump the final overriders. 142 void dump() { 143 VisitedVirtualBasesSetTy VisitedVirtualBases; 144 dump(llvm::errs(), BaseSubobject(MostDerivedClass, CharUnits::Zero()), 145 VisitedVirtualBases); 146 } 147 148}; 149 150#define DUMP_OVERRIDERS 0 151 152FinalOverriders::FinalOverriders(const CXXRecordDecl *MostDerivedClass, 153 uint64_t MostDerivedClassOffset, 154 const CXXRecordDecl *LayoutClass) 155 : MostDerivedClass(MostDerivedClass), 156 MostDerivedClassOffset(MostDerivedClassOffset), LayoutClass(LayoutClass), 157 Context(MostDerivedClass->getASTContext()), 158 MostDerivedClassLayout(Context.getASTRecordLayout(MostDerivedClass)) { 159 160 // Compute base offsets. 161 SubobjectOffsetMapTy SubobjectOffsets; 162 SubobjectOffsetMapTy SubobjectLayoutClassOffsets; 163 SubobjectCountMapTy SubobjectCounts; 164 ComputeBaseOffsets(BaseSubobject(MostDerivedClass, CharUnits::Zero()), 165 /*IsVirtual=*/false, 166 Context.toCharUnitsFromBits(MostDerivedClassOffset), 167 SubobjectOffsets, SubobjectLayoutClassOffsets, 168 SubobjectCounts); 169 170 // Get the the final overriders. 171 CXXFinalOverriderMap FinalOverriders; 172 MostDerivedClass->getFinalOverriders(FinalOverriders); 173 174 for (CXXFinalOverriderMap::const_iterator I = FinalOverriders.begin(), 175 E = FinalOverriders.end(); I != E; ++I) { 176 const CXXMethodDecl *MD = I->first; 177 const OverridingMethods& Methods = I->second; 178 179 for (OverridingMethods::const_iterator I = Methods.begin(), 180 E = Methods.end(); I != E; ++I) { 181 unsigned SubobjectNumber = I->first; 182 assert(SubobjectOffsets.count(std::make_pair(MD->getParent(), 183 SubobjectNumber)) && 184 "Did not find subobject offset!"); 185 186 CharUnits BaseOffset = SubobjectOffsets[std::make_pair(MD->getParent(), 187 SubobjectNumber)]; 188 189 assert(I->second.size() == 1 && "Final overrider is not unique!"); 190 const UniqueVirtualMethod &Method = I->second.front(); 191 192 const CXXRecordDecl *OverriderRD = Method.Method->getParent(); 193 assert(SubobjectLayoutClassOffsets.count( 194 std::make_pair(OverriderRD, Method.Subobject)) 195 && "Did not find subobject offset!"); 196 CharUnits OverriderOffset = 197 SubobjectLayoutClassOffsets[std::make_pair(OverriderRD, 198 Method.Subobject)]; 199 200 OverriderInfo& Overrider = OverridersMap[std::make_pair(MD, BaseOffset)]; 201 assert(!Overrider.Method && "Overrider should not exist yet!"); 202 203 Overrider.Offset = OverriderOffset; 204 Overrider.Method = Method.Method; 205 } 206 } 207 208#if DUMP_OVERRIDERS 209 // And dump them (for now). 210 dump(); 211#endif 212} 213 214static BaseOffset ComputeBaseOffset(ASTContext &Context, 215 const CXXRecordDecl *DerivedRD, 216 const CXXBasePath &Path) { 217 int64_t NonVirtualOffset = 0; 218 219 unsigned NonVirtualStart = 0; 220 const CXXRecordDecl *VirtualBase = 0; 221 222 // First, look for the virtual base class. 223 for (unsigned I = 0, E = Path.size(); I != E; ++I) { 224 const CXXBasePathElement &Element = Path[I]; 225 226 if (Element.Base->isVirtual()) { 227 // FIXME: Can we break when we find the first virtual base? 228 // (If we can't, can't we just iterate over the path in reverse order?) 229 NonVirtualStart = I + 1; 230 QualType VBaseType = Element.Base->getType(); 231 VirtualBase = 232 cast<CXXRecordDecl>(VBaseType->getAs<RecordType>()->getDecl()); 233 } 234 } 235 236 // Now compute the non-virtual offset. 237 for (unsigned I = NonVirtualStart, E = Path.size(); I != E; ++I) { 238 const CXXBasePathElement &Element = Path[I]; 239 240 // Check the base class offset. 241 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Element.Class); 242 243 const RecordType *BaseType = Element.Base->getType()->getAs<RecordType>(); 244 const CXXRecordDecl *Base = cast<CXXRecordDecl>(BaseType->getDecl()); 245 246 NonVirtualOffset += Layout.getBaseClassOffsetInBits(Base); 247 } 248 249 // FIXME: This should probably use CharUnits or something. Maybe we should 250 // even change the base offsets in ASTRecordLayout to be specified in 251 // CharUnits. 252 return BaseOffset(DerivedRD, VirtualBase, NonVirtualOffset / 8); 253 254} 255 256static BaseOffset ComputeBaseOffset(ASTContext &Context, 257 const CXXRecordDecl *BaseRD, 258 const CXXRecordDecl *DerivedRD) { 259 CXXBasePaths Paths(/*FindAmbiguities=*/false, 260 /*RecordPaths=*/true, /*DetectVirtual=*/false); 261 262 if (!const_cast<CXXRecordDecl *>(DerivedRD)-> 263 isDerivedFrom(const_cast<CXXRecordDecl *>(BaseRD), Paths)) { 264 assert(false && "Class must be derived from the passed in base class!"); 265 return BaseOffset(); 266 } 267 268 return ComputeBaseOffset(Context, DerivedRD, Paths.front()); 269} 270 271static BaseOffset 272ComputeReturnAdjustmentBaseOffset(ASTContext &Context, 273 const CXXMethodDecl *DerivedMD, 274 const CXXMethodDecl *BaseMD) { 275 const FunctionType *BaseFT = BaseMD->getType()->getAs<FunctionType>(); 276 const FunctionType *DerivedFT = DerivedMD->getType()->getAs<FunctionType>(); 277 278 // Canonicalize the return types. 279 CanQualType CanDerivedReturnType = 280 Context.getCanonicalType(DerivedFT->getResultType()); 281 CanQualType CanBaseReturnType = 282 Context.getCanonicalType(BaseFT->getResultType()); 283 284 assert(CanDerivedReturnType->getTypeClass() == 285 CanBaseReturnType->getTypeClass() && 286 "Types must have same type class!"); 287 288 if (CanDerivedReturnType == CanBaseReturnType) { 289 // No adjustment needed. 290 return BaseOffset(); 291 } 292 293 if (isa<ReferenceType>(CanDerivedReturnType)) { 294 CanDerivedReturnType = 295 CanDerivedReturnType->getAs<ReferenceType>()->getPointeeType(); 296 CanBaseReturnType = 297 CanBaseReturnType->getAs<ReferenceType>()->getPointeeType(); 298 } else if (isa<PointerType>(CanDerivedReturnType)) { 299 CanDerivedReturnType = 300 CanDerivedReturnType->getAs<PointerType>()->getPointeeType(); 301 CanBaseReturnType = 302 CanBaseReturnType->getAs<PointerType>()->getPointeeType(); 303 } else { 304 assert(false && "Unexpected return type!"); 305 } 306 307 // We need to compare unqualified types here; consider 308 // const T *Base::foo(); 309 // T *Derived::foo(); 310 if (CanDerivedReturnType.getUnqualifiedType() == 311 CanBaseReturnType.getUnqualifiedType()) { 312 // No adjustment needed. 313 return BaseOffset(); 314 } 315 316 const CXXRecordDecl *DerivedRD = 317 cast<CXXRecordDecl>(cast<RecordType>(CanDerivedReturnType)->getDecl()); 318 319 const CXXRecordDecl *BaseRD = 320 cast<CXXRecordDecl>(cast<RecordType>(CanBaseReturnType)->getDecl()); 321 322 return ComputeBaseOffset(Context, BaseRD, DerivedRD); 323} 324 325void 326FinalOverriders::ComputeBaseOffsets(BaseSubobject Base, bool IsVirtual, 327 CharUnits OffsetInLayoutClass, 328 SubobjectOffsetMapTy &SubobjectOffsets, 329 SubobjectOffsetMapTy &SubobjectLayoutClassOffsets, 330 SubobjectCountMapTy &SubobjectCounts) { 331 const CXXRecordDecl *RD = Base.getBase(); 332 333 unsigned SubobjectNumber = 0; 334 if (!IsVirtual) 335 SubobjectNumber = ++SubobjectCounts[RD]; 336 337 // Set up the subobject to offset mapping. 338 assert(!SubobjectOffsets.count(std::make_pair(RD, SubobjectNumber)) 339 && "Subobject offset already exists!"); 340 assert(!SubobjectLayoutClassOffsets.count(std::make_pair(RD, SubobjectNumber)) 341 && "Subobject offset already exists!"); 342 343 SubobjectOffsets[std::make_pair(RD, SubobjectNumber)] = Base.getBaseOffset(); 344 SubobjectLayoutClassOffsets[std::make_pair(RD, SubobjectNumber)] = 345 OffsetInLayoutClass; 346 347 // Traverse our bases. 348 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), 349 E = RD->bases_end(); I != E; ++I) { 350 const CXXRecordDecl *BaseDecl = 351 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); 352 353 CharUnits BaseOffset; 354 CharUnits BaseOffsetInLayoutClass; 355 if (I->isVirtual()) { 356 // Check if we've visited this virtual base before. 357 if (SubobjectOffsets.count(std::make_pair(BaseDecl, 0))) 358 continue; 359 360 const ASTRecordLayout &LayoutClassLayout = 361 Context.getASTRecordLayout(LayoutClass); 362 363 BaseOffset = MostDerivedClassLayout.getVBaseClassOffset(BaseDecl); 364 BaseOffsetInLayoutClass = 365 LayoutClassLayout.getVBaseClassOffset(BaseDecl); 366 } else { 367 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); 368 CharUnits Offset = Layout.getBaseClassOffset(BaseDecl); 369 370 BaseOffset = Base.getBaseOffset() + Offset; 371 BaseOffsetInLayoutClass = OffsetInLayoutClass + Offset; 372 } 373 374 ComputeBaseOffsets(BaseSubobject(BaseDecl, BaseOffset), 375 I->isVirtual(), BaseOffsetInLayoutClass, 376 SubobjectOffsets, SubobjectLayoutClassOffsets, 377 SubobjectCounts); 378 } 379} 380 381void FinalOverriders::dump(llvm::raw_ostream &Out, BaseSubobject Base, 382 VisitedVirtualBasesSetTy &VisitedVirtualBases) { 383 const CXXRecordDecl *RD = Base.getBase(); 384 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); 385 386 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), 387 E = RD->bases_end(); I != E; ++I) { 388 const CXXRecordDecl *BaseDecl = 389 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); 390 391 // Ignore bases that don't have any virtual member functions. 392 if (!BaseDecl->isPolymorphic()) 393 continue; 394 395 CharUnits BaseOffset; 396 if (I->isVirtual()) { 397 if (!VisitedVirtualBases.insert(BaseDecl)) { 398 // We've visited this base before. 399 continue; 400 } 401 402 BaseOffset = MostDerivedClassLayout.getVBaseClassOffset(BaseDecl); 403 } else { 404 BaseOffset = Layout.getBaseClassOffset(BaseDecl) + Base.getBaseOffset(); 405 } 406 407 dump(Out, BaseSubobject(BaseDecl, BaseOffset), VisitedVirtualBases); 408 } 409 410 Out << "Final overriders for (" << RD->getQualifiedNameAsString() << ", "; 411 Out << Base.getBaseOffset().getQuantity() << ")\n"; 412 413 // Now dump the overriders for this base subobject. 414 for (CXXRecordDecl::method_iterator I = RD->method_begin(), 415 E = RD->method_end(); I != E; ++I) { 416 const CXXMethodDecl *MD = *I; 417 418 if (!MD->isVirtual()) 419 continue; 420 421 OverriderInfo Overrider = getOverrider(MD, Base.getBaseOffset()); 422 423 Out << " " << MD->getQualifiedNameAsString() << " - ("; 424 Out << Overrider.Method->getQualifiedNameAsString(); 425 Out << ", " << ", " << Overrider.Offset.getQuantity() << ')'; 426 427 BaseOffset Offset; 428 if (!Overrider.Method->isPure()) 429 Offset = ComputeReturnAdjustmentBaseOffset(Context, Overrider.Method, MD); 430 431 if (!Offset.isEmpty()) { 432 Out << " [ret-adj: "; 433 if (Offset.VirtualBase) 434 Out << Offset.VirtualBase->getQualifiedNameAsString() << " vbase, "; 435 436 Out << Offset.NonVirtualOffset << " nv]"; 437 } 438 439 Out << "\n"; 440 } 441} 442 443/// VTableComponent - Represents a single component in a vtable. 444class VTableComponent { 445public: 446 enum Kind { 447 CK_VCallOffset, 448 CK_VBaseOffset, 449 CK_OffsetToTop, 450 CK_RTTI, 451 CK_FunctionPointer, 452 453 /// CK_CompleteDtorPointer - A pointer to the complete destructor. 454 CK_CompleteDtorPointer, 455 456 /// CK_DeletingDtorPointer - A pointer to the deleting destructor. 457 CK_DeletingDtorPointer, 458 459 /// CK_UnusedFunctionPointer - In some cases, a vtable function pointer 460 /// will end up never being called. Such vtable function pointers are 461 /// represented as a CK_UnusedFunctionPointer. 462 CK_UnusedFunctionPointer 463 }; 464 465 static VTableComponent MakeVCallOffset(int64_t Offset) { 466 return VTableComponent(CK_VCallOffset, Offset); 467 } 468 469 static VTableComponent MakeVBaseOffset(int64_t Offset) { 470 return VTableComponent(CK_VBaseOffset, Offset); 471 } 472 473 static VTableComponent MakeOffsetToTop(int64_t Offset) { 474 return VTableComponent(CK_OffsetToTop, Offset); 475 } 476 477 static VTableComponent MakeRTTI(const CXXRecordDecl *RD) { 478 return VTableComponent(CK_RTTI, reinterpret_cast<uintptr_t>(RD)); 479 } 480 481 static VTableComponent MakeFunction(const CXXMethodDecl *MD) { 482 assert(!isa<CXXDestructorDecl>(MD) && 483 "Don't use MakeFunction with destructors!"); 484 485 return VTableComponent(CK_FunctionPointer, 486 reinterpret_cast<uintptr_t>(MD)); 487 } 488 489 static VTableComponent MakeCompleteDtor(const CXXDestructorDecl *DD) { 490 return VTableComponent(CK_CompleteDtorPointer, 491 reinterpret_cast<uintptr_t>(DD)); 492 } 493 494 static VTableComponent MakeDeletingDtor(const CXXDestructorDecl *DD) { 495 return VTableComponent(CK_DeletingDtorPointer, 496 reinterpret_cast<uintptr_t>(DD)); 497 } 498 499 static VTableComponent MakeUnusedFunction(const CXXMethodDecl *MD) { 500 assert(!isa<CXXDestructorDecl>(MD) && 501 "Don't use MakeUnusedFunction with destructors!"); 502 return VTableComponent(CK_UnusedFunctionPointer, 503 reinterpret_cast<uintptr_t>(MD)); 504 } 505 506 static VTableComponent getFromOpaqueInteger(uint64_t I) { 507 return VTableComponent(I); 508 } 509 510 /// getKind - Get the kind of this vtable component. 511 Kind getKind() const { 512 return (Kind)(Value & 0x7); 513 } 514 515 int64_t getVCallOffset() const { 516 assert(getKind() == CK_VCallOffset && "Invalid component kind!"); 517 518 return getOffset(); 519 } 520 521 int64_t getVBaseOffset() const { 522 assert(getKind() == CK_VBaseOffset && "Invalid component kind!"); 523 524 return getOffset(); 525 } 526 527 int64_t getOffsetToTop() const { 528 assert(getKind() == CK_OffsetToTop && "Invalid component kind!"); 529 530 return getOffset(); 531 } 532 533 const CXXRecordDecl *getRTTIDecl() const { 534 assert(getKind() == CK_RTTI && "Invalid component kind!"); 535 536 return reinterpret_cast<CXXRecordDecl *>(getPointer()); 537 } 538 539 const CXXMethodDecl *getFunctionDecl() const { 540 assert(getKind() == CK_FunctionPointer); 541 542 return reinterpret_cast<CXXMethodDecl *>(getPointer()); 543 } 544 545 const CXXDestructorDecl *getDestructorDecl() const { 546 assert((getKind() == CK_CompleteDtorPointer || 547 getKind() == CK_DeletingDtorPointer) && "Invalid component kind!"); 548 549 return reinterpret_cast<CXXDestructorDecl *>(getPointer()); 550 } 551 552 const CXXMethodDecl *getUnusedFunctionDecl() const { 553 assert(getKind() == CK_UnusedFunctionPointer); 554 555 return reinterpret_cast<CXXMethodDecl *>(getPointer()); 556 } 557 558private: 559 VTableComponent(Kind ComponentKind, int64_t Offset) { 560 assert((ComponentKind == CK_VCallOffset || 561 ComponentKind == CK_VBaseOffset || 562 ComponentKind == CK_OffsetToTop) && "Invalid component kind!"); 563 assert(Offset <= ((1LL << 56) - 1) && "Offset is too big!"); 564 565 Value = ((Offset << 3) | ComponentKind); 566 } 567 568 VTableComponent(Kind ComponentKind, uintptr_t Ptr) { 569 assert((ComponentKind == CK_RTTI || 570 ComponentKind == CK_FunctionPointer || 571 ComponentKind == CK_CompleteDtorPointer || 572 ComponentKind == CK_DeletingDtorPointer || 573 ComponentKind == CK_UnusedFunctionPointer) && 574 "Invalid component kind!"); 575 576 assert((Ptr & 7) == 0 && "Pointer not sufficiently aligned!"); 577 578 Value = Ptr | ComponentKind; 579 } 580 581 int64_t getOffset() const { 582 assert((getKind() == CK_VCallOffset || getKind() == CK_VBaseOffset || 583 getKind() == CK_OffsetToTop) && "Invalid component kind!"); 584 585 return Value >> 3; 586 } 587 588 uintptr_t getPointer() const { 589 assert((getKind() == CK_RTTI || 590 getKind() == CK_FunctionPointer || 591 getKind() == CK_CompleteDtorPointer || 592 getKind() == CK_DeletingDtorPointer || 593 getKind() == CK_UnusedFunctionPointer) && 594 "Invalid component kind!"); 595 596 return static_cast<uintptr_t>(Value & ~7ULL); 597 } 598 599 explicit VTableComponent(uint64_t Value) 600 : Value(Value) { } 601 602 /// The kind is stored in the lower 3 bits of the value. For offsets, we 603 /// make use of the facts that classes can't be larger than 2^55 bytes, 604 /// so we store the offset in the lower part of the 61 bytes that remain. 605 /// (The reason that we're not simply using a PointerIntPair here is that we 606 /// need the offsets to be 64-bit, even when on a 32-bit machine). 607 int64_t Value; 608}; 609 610/// VCallOffsetMap - Keeps track of vcall offsets when building a vtable. 611struct VCallOffsetMap { 612 613 typedef std::pair<const CXXMethodDecl *, int64_t> MethodAndOffsetPairTy; 614 615 /// Offsets - Keeps track of methods and their offsets. 616 // FIXME: This should be a real map and not a vector. 617 llvm::SmallVector<MethodAndOffsetPairTy, 16> Offsets; 618 619 /// MethodsCanShareVCallOffset - Returns whether two virtual member functions 620 /// can share the same vcall offset. 621 static bool MethodsCanShareVCallOffset(const CXXMethodDecl *LHS, 622 const CXXMethodDecl *RHS); 623 624public: 625 /// AddVCallOffset - Adds a vcall offset to the map. Returns true if the 626 /// add was successful, or false if there was already a member function with 627 /// the same signature in the map. 628 bool AddVCallOffset(const CXXMethodDecl *MD, int64_t OffsetOffset); 629 630 /// getVCallOffsetOffset - Returns the vcall offset offset (relative to the 631 /// vtable address point) for the given virtual member function. 632 int64_t getVCallOffsetOffset(const CXXMethodDecl *MD); 633 634 // empty - Return whether the offset map is empty or not. 635 bool empty() const { return Offsets.empty(); } 636}; 637 638static bool HasSameVirtualSignature(const CXXMethodDecl *LHS, 639 const CXXMethodDecl *RHS) { 640 ASTContext &C = LHS->getASTContext(); // TODO: thread this down 641 CanQual<FunctionProtoType> 642 LT = C.getCanonicalType(LHS->getType()).getAs<FunctionProtoType>(), 643 RT = C.getCanonicalType(RHS->getType()).getAs<FunctionProtoType>(); 644 645 // Fast-path matches in the canonical types. 646 if (LT == RT) return true; 647 648 // Force the signatures to match. We can't rely on the overrides 649 // list here because there isn't necessarily an inheritance 650 // relationship between the two methods. 651 if (LT.getQualifiers() != RT.getQualifiers() || 652 LT->getNumArgs() != RT->getNumArgs()) 653 return false; 654 for (unsigned I = 0, E = LT->getNumArgs(); I != E; ++I) 655 if (LT->getArgType(I) != RT->getArgType(I)) 656 return false; 657 return true; 658} 659 660bool VCallOffsetMap::MethodsCanShareVCallOffset(const CXXMethodDecl *LHS, 661 const CXXMethodDecl *RHS) { 662 assert(LHS->isVirtual() && "LHS must be virtual!"); 663 assert(RHS->isVirtual() && "LHS must be virtual!"); 664 665 // A destructor can share a vcall offset with another destructor. 666 if (isa<CXXDestructorDecl>(LHS)) 667 return isa<CXXDestructorDecl>(RHS); 668 669 // FIXME: We need to check more things here. 670 671 // The methods must have the same name. 672 DeclarationName LHSName = LHS->getDeclName(); 673 DeclarationName RHSName = RHS->getDeclName(); 674 if (LHSName != RHSName) 675 return false; 676 677 // And the same signatures. 678 return HasSameVirtualSignature(LHS, RHS); 679} 680 681bool VCallOffsetMap::AddVCallOffset(const CXXMethodDecl *MD, 682 int64_t OffsetOffset) { 683 // Check if we can reuse an offset. 684 for (unsigned I = 0, E = Offsets.size(); I != E; ++I) { 685 if (MethodsCanShareVCallOffset(Offsets[I].first, MD)) 686 return false; 687 } 688 689 // Add the offset. 690 Offsets.push_back(MethodAndOffsetPairTy(MD, OffsetOffset)); 691 return true; 692} 693 694int64_t VCallOffsetMap::getVCallOffsetOffset(const CXXMethodDecl *MD) { 695 // Look for an offset. 696 for (unsigned I = 0, E = Offsets.size(); I != E; ++I) { 697 if (MethodsCanShareVCallOffset(Offsets[I].first, MD)) 698 return Offsets[I].second; 699 } 700 701 assert(false && "Should always find a vcall offset offset!"); 702 return 0; 703} 704 705/// VCallAndVBaseOffsetBuilder - Class for building vcall and vbase offsets. 706class VCallAndVBaseOffsetBuilder { 707public: 708 typedef llvm::DenseMap<const CXXRecordDecl *, int64_t> 709 VBaseOffsetOffsetsMapTy; 710 711private: 712 /// MostDerivedClass - The most derived class for which we're building vcall 713 /// and vbase offsets. 714 const CXXRecordDecl *MostDerivedClass; 715 716 /// LayoutClass - The class we're using for layout information. Will be 717 /// different than the most derived class if we're building a construction 718 /// vtable. 719 const CXXRecordDecl *LayoutClass; 720 721 /// Context - The ASTContext which we will use for layout information. 722 ASTContext &Context; 723 724 /// Components - vcall and vbase offset components 725 typedef llvm::SmallVector<VTableComponent, 64> VTableComponentVectorTy; 726 VTableComponentVectorTy Components; 727 728 /// VisitedVirtualBases - Visited virtual bases. 729 llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBases; 730 731 /// VCallOffsets - Keeps track of vcall offsets. 732 VCallOffsetMap VCallOffsets; 733 734 735 /// VBaseOffsetOffsets - Contains the offsets of the virtual base offsets, 736 /// relative to the address point. 737 VBaseOffsetOffsetsMapTy VBaseOffsetOffsets; 738 739 /// FinalOverriders - The final overriders of the most derived class. 740 /// (Can be null when we're not building a vtable of the most derived class). 741 const FinalOverriders *Overriders; 742 743 /// AddVCallAndVBaseOffsets - Add vcall offsets and vbase offsets for the 744 /// given base subobject. 745 void AddVCallAndVBaseOffsets(BaseSubobject Base, bool BaseIsVirtual, 746 uint64_t RealBaseOffset); 747 748 /// AddVCallOffsets - Add vcall offsets for the given base subobject. 749 void AddVCallOffsets(BaseSubobject Base, uint64_t VBaseOffset); 750 751 /// AddVBaseOffsets - Add vbase offsets for the given class. 752 void AddVBaseOffsets(const CXXRecordDecl *Base, uint64_t OffsetInLayoutClass); 753 754 /// getCurrentOffsetOffset - Get the current vcall or vbase offset offset in 755 /// bytes, relative to the vtable address point. 756 int64_t getCurrentOffsetOffset() const; 757 758public: 759 VCallAndVBaseOffsetBuilder(const CXXRecordDecl *MostDerivedClass, 760 const CXXRecordDecl *LayoutClass, 761 const FinalOverriders *Overriders, 762 BaseSubobject Base, bool BaseIsVirtual, 763 uint64_t OffsetInLayoutClass) 764 : MostDerivedClass(MostDerivedClass), LayoutClass(LayoutClass), 765 Context(MostDerivedClass->getASTContext()), Overriders(Overriders) { 766 767 // Add vcall and vbase offsets. 768 AddVCallAndVBaseOffsets(Base, BaseIsVirtual, OffsetInLayoutClass); 769 } 770 771 /// Methods for iterating over the components. 772 typedef VTableComponentVectorTy::const_reverse_iterator const_iterator; 773 const_iterator components_begin() const { return Components.rbegin(); } 774 const_iterator components_end() const { return Components.rend(); } 775 776 const VCallOffsetMap &getVCallOffsets() const { return VCallOffsets; } 777 const VBaseOffsetOffsetsMapTy &getVBaseOffsetOffsets() const { 778 return VBaseOffsetOffsets; 779 } 780}; 781 782void 783VCallAndVBaseOffsetBuilder::AddVCallAndVBaseOffsets(BaseSubobject Base, 784 bool BaseIsVirtual, 785 uint64_t RealBaseOffset) { 786 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base.getBase()); 787 788 // Itanium C++ ABI 2.5.2: 789 // ..in classes sharing a virtual table with a primary base class, the vcall 790 // and vbase offsets added by the derived class all come before the vcall 791 // and vbase offsets required by the base class, so that the latter may be 792 // laid out as required by the base class without regard to additions from 793 // the derived class(es). 794 795 // (Since we're emitting the vcall and vbase offsets in reverse order, we'll 796 // emit them for the primary base first). 797 if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) { 798 bool PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual(); 799 800 CharUnits PrimaryBaseOffset; 801 802 // Get the base offset of the primary base. 803 if (PrimaryBaseIsVirtual) { 804 assert(Layout.getVBaseClassOffsetInBits(PrimaryBase) == 0 && 805 "Primary vbase should have a zero offset!"); 806 807 const ASTRecordLayout &MostDerivedClassLayout = 808 Context.getASTRecordLayout(MostDerivedClass); 809 810 PrimaryBaseOffset = 811 MostDerivedClassLayout.getVBaseClassOffset(PrimaryBase); 812 } else { 813 assert(Layout.getBaseClassOffsetInBits(PrimaryBase) == 0 && 814 "Primary base should have a zero offset!"); 815 816 PrimaryBaseOffset = Base.getBaseOffset(); 817 } 818 819 AddVCallAndVBaseOffsets( 820 BaseSubobject(PrimaryBase,PrimaryBaseOffset), 821 PrimaryBaseIsVirtual, RealBaseOffset); 822 } 823 824 AddVBaseOffsets(Base.getBase(), RealBaseOffset); 825 826 // We only want to add vcall offsets for virtual bases. 827 if (BaseIsVirtual) 828 AddVCallOffsets(Base, RealBaseOffset); 829} 830 831int64_t VCallAndVBaseOffsetBuilder::getCurrentOffsetOffset() const { 832 // OffsetIndex is the index of this vcall or vbase offset, relative to the 833 // vtable address point. (We subtract 3 to account for the information just 834 // above the address point, the RTTI info, the offset to top, and the 835 // vcall offset itself). 836 int64_t OffsetIndex = -(int64_t)(3 + Components.size()); 837 838 // FIXME: We shouldn't use / 8 here. 839 int64_t OffsetOffset = OffsetIndex * 840 (int64_t)Context.Target.getPointerWidth(0) / 8; 841 842 return OffsetOffset; 843} 844 845void VCallAndVBaseOffsetBuilder::AddVCallOffsets(BaseSubobject Base, 846 uint64_t VBaseOffset) { 847 const CXXRecordDecl *RD = Base.getBase(); 848 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); 849 850 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase(); 851 852 // Handle the primary base first. 853 // We only want to add vcall offsets if the base is non-virtual; a virtual 854 // primary base will have its vcall and vbase offsets emitted already. 855 if (PrimaryBase && !Layout.isPrimaryBaseVirtual()) { 856 // Get the base offset of the primary base. 857 assert(Layout.getBaseClassOffsetInBits(PrimaryBase) == 0 && 858 "Primary base should have a zero offset!"); 859 860 AddVCallOffsets(BaseSubobject(PrimaryBase, Base.getBaseOffset()), 861 VBaseOffset); 862 } 863 864 // Add the vcall offsets. 865 for (CXXRecordDecl::method_iterator I = RD->method_begin(), 866 E = RD->method_end(); I != E; ++I) { 867 const CXXMethodDecl *MD = *I; 868 869 if (!MD->isVirtual()) 870 continue; 871 872 int64_t OffsetOffset = getCurrentOffsetOffset(); 873 874 // Don't add a vcall offset if we already have one for this member function 875 // signature. 876 if (!VCallOffsets.AddVCallOffset(MD, OffsetOffset)) 877 continue; 878 879 int64_t Offset = 0; 880 881 if (Overriders) { 882 // Get the final overrider. 883 FinalOverriders::OverriderInfo Overrider = 884 Overriders->getOverrider(MD, Base.getBaseOffset()); 885 886 /// The vcall offset is the offset from the virtual base to the object 887 /// where the function was overridden. 888 // FIXME: We should not use / 8 here. 889 Offset = (int64_t)(Context.toBits(Overrider.Offset) - VBaseOffset) / 8; 890 } 891 892 Components.push_back(VTableComponent::MakeVCallOffset(Offset)); 893 } 894 895 // And iterate over all non-virtual bases (ignoring the primary base). 896 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), 897 E = RD->bases_end(); I != E; ++I) { 898 899 if (I->isVirtual()) 900 continue; 901 902 const CXXRecordDecl *BaseDecl = 903 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); 904 if (BaseDecl == PrimaryBase) 905 continue; 906 907 // Get the base offset of this base. 908 CharUnits BaseOffset = Base.getBaseOffset() + 909 Layout.getBaseClassOffset(BaseDecl); 910 911 AddVCallOffsets(BaseSubobject(BaseDecl, BaseOffset), 912 VBaseOffset); 913 } 914} 915 916void VCallAndVBaseOffsetBuilder::AddVBaseOffsets(const CXXRecordDecl *RD, 917 uint64_t OffsetInLayoutClass) { 918 const ASTRecordLayout &LayoutClassLayout = 919 Context.getASTRecordLayout(LayoutClass); 920 921 // Add vbase offsets. 922 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), 923 E = RD->bases_end(); I != E; ++I) { 924 const CXXRecordDecl *BaseDecl = 925 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); 926 927 // Check if this is a virtual base that we haven't visited before. 928 if (I->isVirtual() && VisitedVirtualBases.insert(BaseDecl)) { 929 // FIXME: We shouldn't use / 8 here. 930 int64_t Offset = 931 (int64_t)(LayoutClassLayout.getVBaseClassOffsetInBits(BaseDecl) - 932 OffsetInLayoutClass) / 8; 933 934 // Add the vbase offset offset. 935 assert(!VBaseOffsetOffsets.count(BaseDecl) && 936 "vbase offset offset already exists!"); 937 938 int64_t VBaseOffsetOffset = getCurrentOffsetOffset(); 939 VBaseOffsetOffsets.insert(std::make_pair(BaseDecl, VBaseOffsetOffset)); 940 941 Components.push_back(VTableComponent::MakeVBaseOffset(Offset)); 942 } 943 944 // Check the base class looking for more vbase offsets. 945 AddVBaseOffsets(BaseDecl, OffsetInLayoutClass); 946 } 947} 948 949/// VTableBuilder - Class for building vtable layout information. 950class VTableBuilder { 951public: 952 /// PrimaryBasesSetVectorTy - A set vector of direct and indirect 953 /// primary bases. 954 typedef llvm::SmallSetVector<const CXXRecordDecl *, 8> 955 PrimaryBasesSetVectorTy; 956 957 typedef llvm::DenseMap<const CXXRecordDecl *, int64_t> 958 VBaseOffsetOffsetsMapTy; 959 960 typedef llvm::DenseMap<BaseSubobject, uint64_t> 961 AddressPointsMapTy; 962 963private: 964 /// VTables - Global vtable information. 965 CodeGenVTables &VTables; 966 967 /// MostDerivedClass - The most derived class for which we're building this 968 /// vtable. 969 const CXXRecordDecl *MostDerivedClass; 970 971 /// MostDerivedClassOffset - If we're building a construction vtable, this 972 /// holds the offset from the layout class to the most derived class. 973 const uint64_t MostDerivedClassOffset; 974 975 /// MostDerivedClassIsVirtual - Whether the most derived class is a virtual 976 /// base. (This only makes sense when building a construction vtable). 977 bool MostDerivedClassIsVirtual; 978 979 /// LayoutClass - The class we're using for layout information. Will be 980 /// different than the most derived class if we're building a construction 981 /// vtable. 982 const CXXRecordDecl *LayoutClass; 983 984 /// Context - The ASTContext which we will use for layout information. 985 ASTContext &Context; 986 987 /// FinalOverriders - The final overriders of the most derived class. 988 const FinalOverriders Overriders; 989 990 /// VCallOffsetsForVBases - Keeps track of vcall offsets for the virtual 991 /// bases in this vtable. 992 llvm::DenseMap<const CXXRecordDecl *, VCallOffsetMap> VCallOffsetsForVBases; 993 994 /// VBaseOffsetOffsets - Contains the offsets of the virtual base offsets for 995 /// the most derived class. 996 VBaseOffsetOffsetsMapTy VBaseOffsetOffsets; 997 998 /// Components - The components of the vtable being built. 999 llvm::SmallVector<VTableComponent, 64> Components; 1000 1001 /// AddressPoints - Address points for the vtable being built. 1002 AddressPointsMapTy AddressPoints; 1003 1004 /// MethodInfo - Contains information about a method in a vtable. 1005 /// (Used for computing 'this' pointer adjustment thunks. 1006 struct MethodInfo { 1007 /// BaseOffset - The base offset of this method. 1008 const CharUnits BaseOffset; 1009 1010 /// BaseOffsetInLayoutClass - The base offset in the layout class of this 1011 /// method. 1012 const CharUnits BaseOffsetInLayoutClass; 1013 1014 /// VTableIndex - The index in the vtable that this method has. 1015 /// (For destructors, this is the index of the complete destructor). 1016 const uint64_t VTableIndex; 1017 1018 MethodInfo(CharUnits BaseOffset, CharUnits BaseOffsetInLayoutClass, 1019 uint64_t VTableIndex) 1020 : BaseOffset(BaseOffset), 1021 BaseOffsetInLayoutClass(BaseOffsetInLayoutClass), 1022 VTableIndex(VTableIndex) { } 1023 1024 MethodInfo() 1025 : BaseOffset(CharUnits::Zero()), 1026 BaseOffsetInLayoutClass(CharUnits::Zero()), 1027 VTableIndex(0) { } 1028 }; 1029 1030 typedef llvm::DenseMap<const CXXMethodDecl *, MethodInfo> MethodInfoMapTy; 1031 1032 /// MethodInfoMap - The information for all methods in the vtable we're 1033 /// currently building. 1034 MethodInfoMapTy MethodInfoMap; 1035 1036 typedef llvm::DenseMap<uint64_t, ThunkInfo> VTableThunksMapTy; 1037 1038 /// VTableThunks - The thunks by vtable index in the vtable currently being 1039 /// built. 1040 VTableThunksMapTy VTableThunks; 1041 1042 typedef llvm::SmallVector<ThunkInfo, 1> ThunkInfoVectorTy; 1043 typedef llvm::DenseMap<const CXXMethodDecl *, ThunkInfoVectorTy> ThunksMapTy; 1044 1045 /// Thunks - A map that contains all the thunks needed for all methods in the 1046 /// most derived class for which the vtable is currently being built. 1047 ThunksMapTy Thunks; 1048 1049 /// AddThunk - Add a thunk for the given method. 1050 void AddThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk); 1051 1052 /// ComputeThisAdjustments - Compute the 'this' pointer adjustments for the 1053 /// part of the vtable we're currently building. 1054 void ComputeThisAdjustments(); 1055 1056 typedef llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBasesSetTy; 1057 1058 /// PrimaryVirtualBases - All known virtual bases who are a primary base of 1059 /// some other base. 1060 VisitedVirtualBasesSetTy PrimaryVirtualBases; 1061 1062 /// ComputeReturnAdjustment - Compute the return adjustment given a return 1063 /// adjustment base offset. 1064 ReturnAdjustment ComputeReturnAdjustment(BaseOffset Offset); 1065 1066 /// ComputeThisAdjustmentBaseOffset - Compute the base offset for adjusting 1067 /// the 'this' pointer from the base subobject to the derived subobject. 1068 BaseOffset ComputeThisAdjustmentBaseOffset(BaseSubobject Base, 1069 BaseSubobject Derived) const; 1070 1071 /// ComputeThisAdjustment - Compute the 'this' pointer adjustment for the 1072 /// given virtual member function, its offset in the layout class and its 1073 /// final overrider. 1074 ThisAdjustment 1075 ComputeThisAdjustment(const CXXMethodDecl *MD, 1076 uint64_t BaseOffsetInLayoutClass, 1077 FinalOverriders::OverriderInfo Overrider); 1078 1079 /// AddMethod - Add a single virtual member function to the vtable 1080 /// components vector. 1081 void AddMethod(const CXXMethodDecl *MD, ReturnAdjustment ReturnAdjustment); 1082 1083 /// IsOverriderUsed - Returns whether the overrider will ever be used in this 1084 /// part of the vtable. 1085 /// 1086 /// Itanium C++ ABI 2.5.2: 1087 /// 1088 /// struct A { virtual void f(); }; 1089 /// struct B : virtual public A { int i; }; 1090 /// struct C : virtual public A { int j; }; 1091 /// struct D : public B, public C {}; 1092 /// 1093 /// When B and C are declared, A is a primary base in each case, so although 1094 /// vcall offsets are allocated in the A-in-B and A-in-C vtables, no this 1095 /// adjustment is required and no thunk is generated. However, inside D 1096 /// objects, A is no longer a primary base of C, so if we allowed calls to 1097 /// C::f() to use the copy of A's vtable in the C subobject, we would need 1098 /// to adjust this from C* to B::A*, which would require a third-party 1099 /// thunk. Since we require that a call to C::f() first convert to A*, 1100 /// C-in-D's copy of A's vtable is never referenced, so this is not 1101 /// necessary. 1102 bool IsOverriderUsed(const CXXMethodDecl *Overrider, 1103 uint64_t BaseOffsetInLayoutClass, 1104 const CXXRecordDecl *FirstBaseInPrimaryBaseChain, 1105 uint64_t FirstBaseOffsetInLayoutClass) const; 1106 1107 1108 /// AddMethods - Add the methods of this base subobject and all its 1109 /// primary bases to the vtable components vector. 1110 void AddMethods(BaseSubobject Base, uint64_t BaseOffsetInLayoutClass, 1111 const CXXRecordDecl *FirstBaseInPrimaryBaseChain, 1112 uint64_t FirstBaseOffsetInLayoutClass, 1113 PrimaryBasesSetVectorTy &PrimaryBases); 1114 1115 // LayoutVTable - Layout the vtable for the given base class, including its 1116 // secondary vtables and any vtables for virtual bases. 1117 void LayoutVTable(); 1118 1119 /// LayoutPrimaryAndSecondaryVTables - Layout the primary vtable for the 1120 /// given base subobject, as well as all its secondary vtables. 1121 /// 1122 /// \param BaseIsMorallyVirtual whether the base subobject is a virtual base 1123 /// or a direct or indirect base of a virtual base. 1124 /// 1125 /// \param BaseIsVirtualInLayoutClass - Whether the base subobject is virtual 1126 /// in the layout class. 1127 void LayoutPrimaryAndSecondaryVTables(BaseSubobject Base, 1128 bool BaseIsMorallyVirtual, 1129 bool BaseIsVirtualInLayoutClass, 1130 uint64_t OffsetInLayoutClass); 1131 1132 /// LayoutSecondaryVTables - Layout the secondary vtables for the given base 1133 /// subobject. 1134 /// 1135 /// \param BaseIsMorallyVirtual whether the base subobject is a virtual base 1136 /// or a direct or indirect base of a virtual base. 1137 void LayoutSecondaryVTables(BaseSubobject Base, bool BaseIsMorallyVirtual, 1138 uint64_t OffsetInLayoutClass); 1139 1140 /// DeterminePrimaryVirtualBases - Determine the primary virtual bases in this 1141 /// class hierarchy. 1142 void DeterminePrimaryVirtualBases(const CXXRecordDecl *RD, 1143 uint64_t OffsetInLayoutClass, 1144 VisitedVirtualBasesSetTy &VBases); 1145 1146 /// LayoutVTablesForVirtualBases - Layout vtables for all virtual bases of the 1147 /// given base (excluding any primary bases). 1148 void LayoutVTablesForVirtualBases(const CXXRecordDecl *RD, 1149 VisitedVirtualBasesSetTy &VBases); 1150 1151 /// isBuildingConstructionVTable - Return whether this vtable builder is 1152 /// building a construction vtable. 1153 bool isBuildingConstructorVTable() const { 1154 return MostDerivedClass != LayoutClass; 1155 } 1156 1157public: 1158 VTableBuilder(CodeGenVTables &VTables, const CXXRecordDecl *MostDerivedClass, 1159 uint64_t MostDerivedClassOffset, bool MostDerivedClassIsVirtual, 1160 const CXXRecordDecl *LayoutClass) 1161 : VTables(VTables), MostDerivedClass(MostDerivedClass), 1162 MostDerivedClassOffset(MostDerivedClassOffset), 1163 MostDerivedClassIsVirtual(MostDerivedClassIsVirtual), 1164 LayoutClass(LayoutClass), Context(MostDerivedClass->getASTContext()), 1165 Overriders(MostDerivedClass, MostDerivedClassOffset, LayoutClass) { 1166 1167 LayoutVTable(); 1168 } 1169 1170 ThunksMapTy::const_iterator thunks_begin() const { 1171 return Thunks.begin(); 1172 } 1173 1174 ThunksMapTy::const_iterator thunks_end() const { 1175 return Thunks.end(); 1176 } 1177 1178 const VBaseOffsetOffsetsMapTy &getVBaseOffsetOffsets() const { 1179 return VBaseOffsetOffsets; 1180 } 1181 1182 /// getNumVTableComponents - Return the number of components in the vtable 1183 /// currently built. 1184 uint64_t getNumVTableComponents() const { 1185 return Components.size(); 1186 } 1187 1188 const uint64_t *vtable_components_data_begin() const { 1189 return reinterpret_cast<const uint64_t *>(Components.begin()); 1190 } 1191 1192 const uint64_t *vtable_components_data_end() const { 1193 return reinterpret_cast<const uint64_t *>(Components.end()); 1194 } 1195 1196 AddressPointsMapTy::const_iterator address_points_begin() const { 1197 return AddressPoints.begin(); 1198 } 1199 1200 AddressPointsMapTy::const_iterator address_points_end() const { 1201 return AddressPoints.end(); 1202 } 1203 1204 VTableThunksMapTy::const_iterator vtable_thunks_begin() const { 1205 return VTableThunks.begin(); 1206 } 1207 1208 VTableThunksMapTy::const_iterator vtable_thunks_end() const { 1209 return VTableThunks.end(); 1210 } 1211 1212 /// dumpLayout - Dump the vtable layout. 1213 void dumpLayout(llvm::raw_ostream&); 1214}; 1215 1216void VTableBuilder::AddThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk) { 1217 assert(!isBuildingConstructorVTable() && 1218 "Can't add thunks for construction vtable"); 1219 1220 llvm::SmallVector<ThunkInfo, 1> &ThunksVector = Thunks[MD]; 1221 1222 // Check if we have this thunk already. 1223 if (std::find(ThunksVector.begin(), ThunksVector.end(), Thunk) != 1224 ThunksVector.end()) 1225 return; 1226 1227 ThunksVector.push_back(Thunk); 1228} 1229 1230typedef llvm::SmallPtrSet<const CXXMethodDecl *, 8> OverriddenMethodsSetTy; 1231 1232/// ComputeAllOverriddenMethods - Given a method decl, will return a set of all 1233/// the overridden methods that the function decl overrides. 1234static void 1235ComputeAllOverriddenMethods(const CXXMethodDecl *MD, 1236 OverriddenMethodsSetTy& OverriddenMethods) { 1237 assert(MD->isVirtual() && "Method is not virtual!"); 1238 1239 for (CXXMethodDecl::method_iterator I = MD->begin_overridden_methods(), 1240 E = MD->end_overridden_methods(); I != E; ++I) { 1241 const CXXMethodDecl *OverriddenMD = *I; 1242 1243 OverriddenMethods.insert(OverriddenMD); 1244 1245 ComputeAllOverriddenMethods(OverriddenMD, OverriddenMethods); 1246 } 1247} 1248 1249void VTableBuilder::ComputeThisAdjustments() { 1250 // Now go through the method info map and see if any of the methods need 1251 // 'this' pointer adjustments. 1252 for (MethodInfoMapTy::const_iterator I = MethodInfoMap.begin(), 1253 E = MethodInfoMap.end(); I != E; ++I) { 1254 const CXXMethodDecl *MD = I->first; 1255 const MethodInfo &MethodInfo = I->second; 1256 1257 // Ignore adjustments for unused function pointers. 1258 uint64_t VTableIndex = MethodInfo.VTableIndex; 1259 if (Components[VTableIndex].getKind() == 1260 VTableComponent::CK_UnusedFunctionPointer) 1261 continue; 1262 1263 // Get the final overrider for this method. 1264 FinalOverriders::OverriderInfo Overrider = 1265 Overriders.getOverrider(MD, MethodInfo.BaseOffset); 1266 1267 // Check if we need an adjustment at all. 1268 if (MethodInfo.BaseOffsetInLayoutClass == Overrider.Offset) { 1269 // When a return thunk is needed by a derived class that overrides a 1270 // virtual base, gcc uses a virtual 'this' adjustment as well. 1271 // While the thunk itself might be needed by vtables in subclasses or 1272 // in construction vtables, there doesn't seem to be a reason for using 1273 // the thunk in this vtable. Still, we do so to match gcc. 1274 if (VTableThunks.lookup(VTableIndex).Return.isEmpty()) 1275 continue; 1276 } 1277 1278 ThisAdjustment ThisAdjustment = 1279 ComputeThisAdjustment(MD, 1280 Context.toBits(MethodInfo.BaseOffsetInLayoutClass), Overrider); 1281 1282 if (ThisAdjustment.isEmpty()) 1283 continue; 1284 1285 // Add it. 1286 VTableThunks[VTableIndex].This = ThisAdjustment; 1287 1288 if (isa<CXXDestructorDecl>(MD)) { 1289 // Add an adjustment for the deleting destructor as well. 1290 VTableThunks[VTableIndex + 1].This = ThisAdjustment; 1291 } 1292 } 1293 1294 /// Clear the method info map. 1295 MethodInfoMap.clear(); 1296 1297 if (isBuildingConstructorVTable()) { 1298 // We don't need to store thunk information for construction vtables. 1299 return; 1300 } 1301 1302 for (VTableThunksMapTy::const_iterator I = VTableThunks.begin(), 1303 E = VTableThunks.end(); I != E; ++I) { 1304 const VTableComponent &Component = Components[I->first]; 1305 const ThunkInfo &Thunk = I->second; 1306 const CXXMethodDecl *MD; 1307 1308 switch (Component.getKind()) { 1309 default: 1310 llvm_unreachable("Unexpected vtable component kind!"); 1311 case VTableComponent::CK_FunctionPointer: 1312 MD = Component.getFunctionDecl(); 1313 break; 1314 case VTableComponent::CK_CompleteDtorPointer: 1315 MD = Component.getDestructorDecl(); 1316 break; 1317 case VTableComponent::CK_DeletingDtorPointer: 1318 // We've already added the thunk when we saw the complete dtor pointer. 1319 continue; 1320 } 1321 1322 if (MD->getParent() == MostDerivedClass) 1323 AddThunk(MD, Thunk); 1324 } 1325} 1326 1327ReturnAdjustment VTableBuilder::ComputeReturnAdjustment(BaseOffset Offset) { 1328 ReturnAdjustment Adjustment; 1329 1330 if (!Offset.isEmpty()) { 1331 if (Offset.VirtualBase) { 1332 // Get the virtual base offset offset. 1333 if (Offset.DerivedClass == MostDerivedClass) { 1334 // We can get the offset offset directly from our map. 1335 Adjustment.VBaseOffsetOffset = 1336 VBaseOffsetOffsets.lookup(Offset.VirtualBase); 1337 } else { 1338 Adjustment.VBaseOffsetOffset = 1339 VTables.getVirtualBaseOffsetOffset(Offset.DerivedClass, 1340 Offset.VirtualBase); 1341 } 1342 } 1343 1344 Adjustment.NonVirtual = Offset.NonVirtualOffset; 1345 } 1346 1347 return Adjustment; 1348} 1349 1350BaseOffset 1351VTableBuilder::ComputeThisAdjustmentBaseOffset(BaseSubobject Base, 1352 BaseSubobject Derived) const { 1353 const CXXRecordDecl *BaseRD = Base.getBase(); 1354 const CXXRecordDecl *DerivedRD = Derived.getBase(); 1355 1356 CXXBasePaths Paths(/*FindAmbiguities=*/true, 1357 /*RecordPaths=*/true, /*DetectVirtual=*/true); 1358 1359 if (!const_cast<CXXRecordDecl *>(DerivedRD)-> 1360 isDerivedFrom(const_cast<CXXRecordDecl *>(BaseRD), Paths)) { 1361 assert(false && "Class must be derived from the passed in base class!"); 1362 return BaseOffset(); 1363 } 1364 1365 // We have to go through all the paths, and see which one leads us to the 1366 // right base subobject. 1367 for (CXXBasePaths::const_paths_iterator I = Paths.begin(), E = Paths.end(); 1368 I != E; ++I) { 1369 BaseOffset Offset = ComputeBaseOffset(Context, DerivedRD, *I); 1370 1371 CharUnits OffsetToBaseSubobject = 1372 CharUnits::fromQuantity(Offset.NonVirtualOffset); 1373 1374 if (Offset.VirtualBase) { 1375 // If we have a virtual base class, the non-virtual offset is relative 1376 // to the virtual base class offset. 1377 const ASTRecordLayout &LayoutClassLayout = 1378 Context.getASTRecordLayout(LayoutClass); 1379 1380 /// Get the virtual base offset, relative to the most derived class 1381 /// layout. 1382 OffsetToBaseSubobject += 1383 LayoutClassLayout.getVBaseClassOffset(Offset.VirtualBase); 1384 } else { 1385 // Otherwise, the non-virtual offset is relative to the derived class 1386 // offset. 1387 OffsetToBaseSubobject += Derived.getBaseOffset(); 1388 } 1389 1390 // Check if this path gives us the right base subobject. 1391 if (OffsetToBaseSubobject == Base.getBaseOffset()) { 1392 // Since we're going from the base class _to_ the derived class, we'll 1393 // invert the non-virtual offset here. 1394 Offset.NonVirtualOffset = -Offset.NonVirtualOffset; 1395 return Offset; 1396 } 1397 } 1398 1399 return BaseOffset(); 1400} 1401 1402ThisAdjustment 1403VTableBuilder::ComputeThisAdjustment(const CXXMethodDecl *MD, 1404 uint64_t BaseOffsetInLayoutClass, 1405 FinalOverriders::OverriderInfo Overrider) { 1406 // Ignore adjustments for pure virtual member functions. 1407 if (Overrider.Method->isPure()) 1408 return ThisAdjustment(); 1409 1410 BaseSubobject OverriddenBaseSubobject(MD->getParent(), 1411 Context.toCharUnitsFromBits( 1412 BaseOffsetInLayoutClass)); 1413 1414 BaseSubobject OverriderBaseSubobject(Overrider.Method->getParent(), 1415 Overrider.Offset); 1416 1417 // Compute the adjustment offset. 1418 BaseOffset Offset = ComputeThisAdjustmentBaseOffset(OverriddenBaseSubobject, 1419 OverriderBaseSubobject); 1420 if (Offset.isEmpty()) 1421 return ThisAdjustment(); 1422 1423 ThisAdjustment Adjustment; 1424 1425 if (Offset.VirtualBase) { 1426 // Get the vcall offset map for this virtual base. 1427 VCallOffsetMap &VCallOffsets = VCallOffsetsForVBases[Offset.VirtualBase]; 1428 1429 if (VCallOffsets.empty()) { 1430 // We don't have vcall offsets for this virtual base, go ahead and 1431 // build them. 1432 VCallAndVBaseOffsetBuilder Builder(MostDerivedClass, MostDerivedClass, 1433 /*FinalOverriders=*/0, 1434 BaseSubobject(Offset.VirtualBase, 1435 CharUnits::Zero()), 1436 /*BaseIsVirtual=*/true, 1437 /*OffsetInLayoutClass=*/0); 1438 1439 VCallOffsets = Builder.getVCallOffsets(); 1440 } 1441 1442 Adjustment.VCallOffsetOffset = VCallOffsets.getVCallOffsetOffset(MD); 1443 } 1444 1445 // Set the non-virtual part of the adjustment. 1446 Adjustment.NonVirtual = Offset.NonVirtualOffset; 1447 1448 return Adjustment; 1449} 1450 1451void 1452VTableBuilder::AddMethod(const CXXMethodDecl *MD, 1453 ReturnAdjustment ReturnAdjustment) { 1454 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) { 1455 assert(ReturnAdjustment.isEmpty() && 1456 "Destructor can't have return adjustment!"); 1457 1458 // Add both the complete destructor and the deleting destructor. 1459 Components.push_back(VTableComponent::MakeCompleteDtor(DD)); 1460 Components.push_back(VTableComponent::MakeDeletingDtor(DD)); 1461 } else { 1462 // Add the return adjustment if necessary. 1463 if (!ReturnAdjustment.isEmpty()) 1464 VTableThunks[Components.size()].Return = ReturnAdjustment; 1465 1466 // Add the function. 1467 Components.push_back(VTableComponent::MakeFunction(MD)); 1468 } 1469} 1470 1471/// OverridesIndirectMethodInBase - Return whether the given member function 1472/// overrides any methods in the set of given bases. 1473/// Unlike OverridesMethodInBase, this checks "overriders of overriders". 1474/// For example, if we have: 1475/// 1476/// struct A { virtual void f(); } 1477/// struct B : A { virtual void f(); } 1478/// struct C : B { virtual void f(); } 1479/// 1480/// OverridesIndirectMethodInBase will return true if given C::f as the method 1481/// and { A } as the set of bases. 1482static bool 1483OverridesIndirectMethodInBases(const CXXMethodDecl *MD, 1484 VTableBuilder::PrimaryBasesSetVectorTy &Bases) { 1485 if (Bases.count(MD->getParent())) 1486 return true; 1487 1488 for (CXXMethodDecl::method_iterator I = MD->begin_overridden_methods(), 1489 E = MD->end_overridden_methods(); I != E; ++I) { 1490 const CXXMethodDecl *OverriddenMD = *I; 1491 1492 // Check "indirect overriders". 1493 if (OverridesIndirectMethodInBases(OverriddenMD, Bases)) 1494 return true; 1495 } 1496 1497 return false; 1498} 1499 1500bool 1501VTableBuilder::IsOverriderUsed(const CXXMethodDecl *Overrider, 1502 uint64_t BaseOffsetInLayoutClass, 1503 const CXXRecordDecl *FirstBaseInPrimaryBaseChain, 1504 uint64_t FirstBaseOffsetInLayoutClass) const { 1505 // If the base and the first base in the primary base chain have the same 1506 // offsets, then this overrider will be used. 1507 if (BaseOffsetInLayoutClass == FirstBaseOffsetInLayoutClass) 1508 return true; 1509 1510 // We know now that Base (or a direct or indirect base of it) is a primary 1511 // base in part of the class hierarchy, but not a primary base in the most 1512 // derived class. 1513 1514 // If the overrider is the first base in the primary base chain, we know 1515 // that the overrider will be used. 1516 if (Overrider->getParent() == FirstBaseInPrimaryBaseChain) 1517 return true; 1518 1519 VTableBuilder::PrimaryBasesSetVectorTy PrimaryBases; 1520 1521 const CXXRecordDecl *RD = FirstBaseInPrimaryBaseChain; 1522 PrimaryBases.insert(RD); 1523 1524 // Now traverse the base chain, starting with the first base, until we find 1525 // the base that is no longer a primary base. 1526 while (true) { 1527 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); 1528 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase(); 1529 1530 if (!PrimaryBase) 1531 break; 1532 1533 if (Layout.isPrimaryBaseVirtual()) { 1534 assert(Layout.getVBaseClassOffsetInBits(PrimaryBase) == 0 && 1535 "Primary base should always be at offset 0!"); 1536 1537 const ASTRecordLayout &LayoutClassLayout = 1538 Context.getASTRecordLayout(LayoutClass); 1539 1540 // Now check if this is the primary base that is not a primary base in the 1541 // most derived class. 1542 if (LayoutClassLayout.getVBaseClassOffsetInBits(PrimaryBase) != 1543 FirstBaseOffsetInLayoutClass) { 1544 // We found it, stop walking the chain. 1545 break; 1546 } 1547 } else { 1548 assert(Layout.getBaseClassOffsetInBits(PrimaryBase) == 0 && 1549 "Primary base should always be at offset 0!"); 1550 } 1551 1552 if (!PrimaryBases.insert(PrimaryBase)) 1553 assert(false && "Found a duplicate primary base!"); 1554 1555 RD = PrimaryBase; 1556 } 1557 1558 // If the final overrider is an override of one of the primary bases, 1559 // then we know that it will be used. 1560 return OverridesIndirectMethodInBases(Overrider, PrimaryBases); 1561} 1562 1563/// FindNearestOverriddenMethod - Given a method, returns the overridden method 1564/// from the nearest base. Returns null if no method was found. 1565static const CXXMethodDecl * 1566FindNearestOverriddenMethod(const CXXMethodDecl *MD, 1567 VTableBuilder::PrimaryBasesSetVectorTy &Bases) { 1568 OverriddenMethodsSetTy OverriddenMethods; 1569 ComputeAllOverriddenMethods(MD, OverriddenMethods); 1570 1571 for (int I = Bases.size(), E = 0; I != E; --I) { 1572 const CXXRecordDecl *PrimaryBase = Bases[I - 1]; 1573 1574 // Now check the overriden methods. 1575 for (OverriddenMethodsSetTy::const_iterator I = OverriddenMethods.begin(), 1576 E = OverriddenMethods.end(); I != E; ++I) { 1577 const CXXMethodDecl *OverriddenMD = *I; 1578 1579 // We found our overridden method. 1580 if (OverriddenMD->getParent() == PrimaryBase) 1581 return OverriddenMD; 1582 } 1583 } 1584 1585 return 0; 1586} 1587 1588void 1589VTableBuilder::AddMethods(BaseSubobject Base, uint64_t BaseOffsetInLayoutClass, 1590 const CXXRecordDecl *FirstBaseInPrimaryBaseChain, 1591 uint64_t FirstBaseOffsetInLayoutClass, 1592 PrimaryBasesSetVectorTy &PrimaryBases) { 1593 const CXXRecordDecl *RD = Base.getBase(); 1594 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); 1595 1596 if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) { 1597 CharUnits PrimaryBaseOffset; 1598 uint64_t PrimaryBaseOffsetInLayoutClass; 1599 if (Layout.isPrimaryBaseVirtual()) { 1600 assert(Layout.getVBaseClassOffsetInBits(PrimaryBase) == 0 && 1601 "Primary vbase should have a zero offset!"); 1602 1603 const ASTRecordLayout &MostDerivedClassLayout = 1604 Context.getASTRecordLayout(MostDerivedClass); 1605 1606 PrimaryBaseOffset = 1607 MostDerivedClassLayout.getVBaseClassOffset(PrimaryBase); 1608 1609 const ASTRecordLayout &LayoutClassLayout = 1610 Context.getASTRecordLayout(LayoutClass); 1611 1612 PrimaryBaseOffsetInLayoutClass = 1613 LayoutClassLayout.getVBaseClassOffsetInBits(PrimaryBase); 1614 } else { 1615 assert(Layout.getBaseClassOffsetInBits(PrimaryBase) == 0 && 1616 "Primary base should have a zero offset!"); 1617 1618 PrimaryBaseOffset = Base.getBaseOffset(); 1619 PrimaryBaseOffsetInLayoutClass = BaseOffsetInLayoutClass; 1620 } 1621 1622 AddMethods(BaseSubobject(PrimaryBase, PrimaryBaseOffset), 1623 PrimaryBaseOffsetInLayoutClass, FirstBaseInPrimaryBaseChain, 1624 FirstBaseOffsetInLayoutClass, PrimaryBases); 1625 1626 if (!PrimaryBases.insert(PrimaryBase)) 1627 assert(false && "Found a duplicate primary base!"); 1628 } 1629 1630 // Now go through all virtual member functions and add them. 1631 for (CXXRecordDecl::method_iterator I = RD->method_begin(), 1632 E = RD->method_end(); I != E; ++I) { 1633 const CXXMethodDecl *MD = *I; 1634 1635 if (!MD->isVirtual()) 1636 continue; 1637 1638 // Get the final overrider. 1639 FinalOverriders::OverriderInfo Overrider = 1640 Overriders.getOverrider(MD, Base.getBaseOffset()); 1641 1642 // Check if this virtual member function overrides a method in a primary 1643 // base. If this is the case, and the return type doesn't require adjustment 1644 // then we can just use the member function from the primary base. 1645 if (const CXXMethodDecl *OverriddenMD = 1646 FindNearestOverriddenMethod(MD, PrimaryBases)) { 1647 if (ComputeReturnAdjustmentBaseOffset(Context, MD, 1648 OverriddenMD).isEmpty()) { 1649 // Replace the method info of the overridden method with our own 1650 // method. 1651 assert(MethodInfoMap.count(OverriddenMD) && 1652 "Did not find the overridden method!"); 1653 MethodInfo &OverriddenMethodInfo = MethodInfoMap[OverriddenMD]; 1654 1655 MethodInfo MethodInfo(Base.getBaseOffset(), 1656 Context.toCharUnitsFromBits(BaseOffsetInLayoutClass), 1657 OverriddenMethodInfo.VTableIndex); 1658 1659 assert(!MethodInfoMap.count(MD) && 1660 "Should not have method info for this method yet!"); 1661 1662 MethodInfoMap.insert(std::make_pair(MD, MethodInfo)); 1663 MethodInfoMap.erase(OverriddenMD); 1664 1665 // If the overridden method exists in a virtual base class or a direct 1666 // or indirect base class of a virtual base class, we need to emit a 1667 // thunk if we ever have a class hierarchy where the base class is not 1668 // a primary base in the complete object. 1669 if (!isBuildingConstructorVTable() && OverriddenMD != MD) { 1670 // Compute the this adjustment. 1671 ThisAdjustment ThisAdjustment = 1672 ComputeThisAdjustment(OverriddenMD, BaseOffsetInLayoutClass, 1673 Overrider); 1674 1675 if (ThisAdjustment.VCallOffsetOffset && 1676 Overrider.Method->getParent() == MostDerivedClass) { 1677 1678 // There's no return adjustment from OverriddenMD and MD, 1679 // but that doesn't mean there isn't one between MD and 1680 // the final overrider. 1681 BaseOffset ReturnAdjustmentOffset = 1682 ComputeReturnAdjustmentBaseOffset(Context, Overrider.Method, MD); 1683 ReturnAdjustment ReturnAdjustment = 1684 ComputeReturnAdjustment(ReturnAdjustmentOffset); 1685 1686 // This is a virtual thunk for the most derived class, add it. 1687 AddThunk(Overrider.Method, 1688 ThunkInfo(ThisAdjustment, ReturnAdjustment)); 1689 } 1690 } 1691 1692 continue; 1693 } 1694 } 1695 1696 // Insert the method info for this method. 1697 MethodInfo MethodInfo(Base.getBaseOffset(), 1698 Context.toCharUnitsFromBits(BaseOffsetInLayoutClass), 1699 Components.size()); 1700 1701 assert(!MethodInfoMap.count(MD) && 1702 "Should not have method info for this method yet!"); 1703 MethodInfoMap.insert(std::make_pair(MD, MethodInfo)); 1704 1705 // Check if this overrider is going to be used. 1706 const CXXMethodDecl *OverriderMD = Overrider.Method; 1707 if (!IsOverriderUsed(OverriderMD, BaseOffsetInLayoutClass, 1708 FirstBaseInPrimaryBaseChain, 1709 FirstBaseOffsetInLayoutClass)) { 1710 Components.push_back(VTableComponent::MakeUnusedFunction(OverriderMD)); 1711 continue; 1712 } 1713 1714 // Check if this overrider needs a return adjustment. 1715 // We don't want to do this for pure virtual member functions. 1716 BaseOffset ReturnAdjustmentOffset; 1717 if (!OverriderMD->isPure()) { 1718 ReturnAdjustmentOffset = 1719 ComputeReturnAdjustmentBaseOffset(Context, OverriderMD, MD); 1720 } 1721 1722 ReturnAdjustment ReturnAdjustment = 1723 ComputeReturnAdjustment(ReturnAdjustmentOffset); 1724 1725 AddMethod(Overrider.Method, ReturnAdjustment); 1726 } 1727} 1728 1729void VTableBuilder::LayoutVTable() { 1730 LayoutPrimaryAndSecondaryVTables(BaseSubobject(MostDerivedClass, 1731 CharUnits::Zero()), 1732 /*BaseIsMorallyVirtual=*/false, 1733 MostDerivedClassIsVirtual, 1734 MostDerivedClassOffset); 1735 1736 VisitedVirtualBasesSetTy VBases; 1737 1738 // Determine the primary virtual bases. 1739 DeterminePrimaryVirtualBases(MostDerivedClass, MostDerivedClassOffset, 1740 VBases); 1741 VBases.clear(); 1742 1743 LayoutVTablesForVirtualBases(MostDerivedClass, VBases); 1744} 1745 1746void 1747VTableBuilder::LayoutPrimaryAndSecondaryVTables(BaseSubobject Base, 1748 bool BaseIsMorallyVirtual, 1749 bool BaseIsVirtualInLayoutClass, 1750 uint64_t OffsetInLayoutClass) { 1751 assert(Base.getBase()->isDynamicClass() && "class does not have a vtable!"); 1752 1753 // Add vcall and vbase offsets for this vtable. 1754 VCallAndVBaseOffsetBuilder Builder(MostDerivedClass, LayoutClass, &Overriders, 1755 Base, BaseIsVirtualInLayoutClass, 1756 OffsetInLayoutClass); 1757 Components.append(Builder.components_begin(), Builder.components_end()); 1758 1759 // Check if we need to add these vcall offsets. 1760 if (BaseIsVirtualInLayoutClass && !Builder.getVCallOffsets().empty()) { 1761 VCallOffsetMap &VCallOffsets = VCallOffsetsForVBases[Base.getBase()]; 1762 1763 if (VCallOffsets.empty()) 1764 VCallOffsets = Builder.getVCallOffsets(); 1765 } 1766 1767 // If we're laying out the most derived class we want to keep track of the 1768 // virtual base class offset offsets. 1769 if (Base.getBase() == MostDerivedClass) 1770 VBaseOffsetOffsets = Builder.getVBaseOffsetOffsets(); 1771 1772 // Add the offset to top. 1773 // FIXME: We should not use / 8 here. 1774 int64_t OffsetToTop = -(int64_t)(OffsetInLayoutClass - 1775 MostDerivedClassOffset) / 8; 1776 Components.push_back(VTableComponent::MakeOffsetToTop(OffsetToTop)); 1777 1778 // Next, add the RTTI. 1779 Components.push_back(VTableComponent::MakeRTTI(MostDerivedClass)); 1780 1781 uint64_t AddressPoint = Components.size(); 1782 1783 // Now go through all virtual member functions and add them. 1784 PrimaryBasesSetVectorTy PrimaryBases; 1785 AddMethods(Base, OffsetInLayoutClass, Base.getBase(), OffsetInLayoutClass, 1786 PrimaryBases); 1787 1788 // Compute 'this' pointer adjustments. 1789 ComputeThisAdjustments(); 1790 1791 // Add all address points. 1792 const CXXRecordDecl *RD = Base.getBase(); 1793 while (true) { 1794 AddressPoints.insert(std::make_pair( 1795 BaseSubobject(RD, Context.toCharUnitsFromBits(OffsetInLayoutClass)), 1796 AddressPoint)); 1797 1798 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); 1799 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase(); 1800 1801 if (!PrimaryBase) 1802 break; 1803 1804 if (Layout.isPrimaryBaseVirtual()) { 1805 // Check if this virtual primary base is a primary base in the layout 1806 // class. If it's not, we don't want to add it. 1807 const ASTRecordLayout &LayoutClassLayout = 1808 Context.getASTRecordLayout(LayoutClass); 1809 1810 if (LayoutClassLayout.getVBaseClassOffsetInBits(PrimaryBase) != 1811 OffsetInLayoutClass) { 1812 // We don't want to add this class (or any of its primary bases). 1813 break; 1814 } 1815 } 1816 1817 RD = PrimaryBase; 1818 } 1819 1820 // Layout secondary vtables. 1821 LayoutSecondaryVTables(Base, BaseIsMorallyVirtual, OffsetInLayoutClass); 1822} 1823 1824void VTableBuilder::LayoutSecondaryVTables(BaseSubobject Base, 1825 bool BaseIsMorallyVirtual, 1826 uint64_t OffsetInLayoutClass) { 1827 // Itanium C++ ABI 2.5.2: 1828 // Following the primary virtual table of a derived class are secondary 1829 // virtual tables for each of its proper base classes, except any primary 1830 // base(s) with which it shares its primary virtual table. 1831 1832 const CXXRecordDecl *RD = Base.getBase(); 1833 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); 1834 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase(); 1835 1836 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), 1837 E = RD->bases_end(); I != E; ++I) { 1838 // Ignore virtual bases, we'll emit them later. 1839 if (I->isVirtual()) 1840 continue; 1841 1842 const CXXRecordDecl *BaseDecl = 1843 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); 1844 1845 // Ignore bases that don't have a vtable. 1846 if (!BaseDecl->isDynamicClass()) 1847 continue; 1848 1849 if (isBuildingConstructorVTable()) { 1850 // Itanium C++ ABI 2.6.4: 1851 // Some of the base class subobjects may not need construction virtual 1852 // tables, which will therefore not be present in the construction 1853 // virtual table group, even though the subobject virtual tables are 1854 // present in the main virtual table group for the complete object. 1855 if (!BaseIsMorallyVirtual && !BaseDecl->getNumVBases()) 1856 continue; 1857 } 1858 1859 // Get the base offset of this base. 1860 CharUnits RelativeBaseOffset = Layout.getBaseClassOffset(BaseDecl); 1861 CharUnits BaseOffset = Base.getBaseOffset() + RelativeBaseOffset; 1862 1863 CharUnits BaseOffsetInLayoutClass = 1864 Context.toCharUnitsFromBits(OffsetInLayoutClass) + RelativeBaseOffset; 1865 1866 // Don't emit a secondary vtable for a primary base. We might however want 1867 // to emit secondary vtables for other bases of this base. 1868 if (BaseDecl == PrimaryBase) { 1869 LayoutSecondaryVTables( 1870 BaseSubobject(BaseDecl, BaseOffset), 1871 BaseIsMorallyVirtual, Context.toBits(BaseOffsetInLayoutClass)); 1872 continue; 1873 } 1874 1875 // Layout the primary vtable (and any secondary vtables) for this base. 1876 LayoutPrimaryAndSecondaryVTables( 1877 BaseSubobject(BaseDecl, BaseOffset), 1878 BaseIsMorallyVirtual, 1879 /*BaseIsVirtualInLayoutClass=*/false, 1880 Context.toBits(BaseOffsetInLayoutClass)); 1881 } 1882} 1883 1884void 1885VTableBuilder::DeterminePrimaryVirtualBases(const CXXRecordDecl *RD, 1886 uint64_t OffsetInLayoutClass, 1887 VisitedVirtualBasesSetTy &VBases) { 1888 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); 1889 1890 // Check if this base has a primary base. 1891 if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) { 1892 1893 // Check if it's virtual. 1894 if (Layout.isPrimaryBaseVirtual()) { 1895 bool IsPrimaryVirtualBase = true; 1896 1897 if (isBuildingConstructorVTable()) { 1898 // Check if the base is actually a primary base in the class we use for 1899 // layout. 1900 const ASTRecordLayout &LayoutClassLayout = 1901 Context.getASTRecordLayout(LayoutClass); 1902 1903 uint64_t PrimaryBaseOffsetInLayoutClass = 1904 LayoutClassLayout.getVBaseClassOffsetInBits(PrimaryBase); 1905 1906 // We know that the base is not a primary base in the layout class if 1907 // the base offsets are different. 1908 if (PrimaryBaseOffsetInLayoutClass != OffsetInLayoutClass) 1909 IsPrimaryVirtualBase = false; 1910 } 1911 1912 if (IsPrimaryVirtualBase) 1913 PrimaryVirtualBases.insert(PrimaryBase); 1914 } 1915 } 1916 1917 // Traverse bases, looking for more primary virtual bases. 1918 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), 1919 E = RD->bases_end(); I != E; ++I) { 1920 const CXXRecordDecl *BaseDecl = 1921 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); 1922 1923 uint64_t BaseOffsetInLayoutClass; 1924 1925 if (I->isVirtual()) { 1926 if (!VBases.insert(BaseDecl)) 1927 continue; 1928 1929 const ASTRecordLayout &LayoutClassLayout = 1930 Context.getASTRecordLayout(LayoutClass); 1931 1932 BaseOffsetInLayoutClass = 1933 LayoutClassLayout.getVBaseClassOffsetInBits(BaseDecl); 1934 } else { 1935 BaseOffsetInLayoutClass = 1936 OffsetInLayoutClass + Layout.getBaseClassOffsetInBits(BaseDecl); 1937 } 1938 1939 DeterminePrimaryVirtualBases(BaseDecl, BaseOffsetInLayoutClass, VBases); 1940 } 1941} 1942 1943void 1944VTableBuilder::LayoutVTablesForVirtualBases(const CXXRecordDecl *RD, 1945 VisitedVirtualBasesSetTy &VBases) { 1946 // Itanium C++ ABI 2.5.2: 1947 // Then come the virtual base virtual tables, also in inheritance graph 1948 // order, and again excluding primary bases (which share virtual tables with 1949 // the classes for which they are primary). 1950 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), 1951 E = RD->bases_end(); I != E; ++I) { 1952 const CXXRecordDecl *BaseDecl = 1953 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); 1954 1955 // Check if this base needs a vtable. (If it's virtual, not a primary base 1956 // of some other class, and we haven't visited it before). 1957 if (I->isVirtual() && BaseDecl->isDynamicClass() && 1958 !PrimaryVirtualBases.count(BaseDecl) && VBases.insert(BaseDecl)) { 1959 const ASTRecordLayout &MostDerivedClassLayout = 1960 Context.getASTRecordLayout(MostDerivedClass); 1961 uint64_t BaseOffset = 1962 MostDerivedClassLayout.getVBaseClassOffsetInBits(BaseDecl); 1963 1964 const ASTRecordLayout &LayoutClassLayout = 1965 Context.getASTRecordLayout(LayoutClass); 1966 uint64_t BaseOffsetInLayoutClass = 1967 LayoutClassLayout.getVBaseClassOffsetInBits(BaseDecl); 1968 1969 LayoutPrimaryAndSecondaryVTables( 1970 BaseSubobject(BaseDecl, Context.toCharUnitsFromBits(BaseOffset)), 1971 /*BaseIsMorallyVirtual=*/true, 1972 /*BaseIsVirtualInLayoutClass=*/true, 1973 BaseOffsetInLayoutClass); 1974 } 1975 1976 // We only need to check the base for virtual base vtables if it actually 1977 // has virtual bases. 1978 if (BaseDecl->getNumVBases()) 1979 LayoutVTablesForVirtualBases(BaseDecl, VBases); 1980 } 1981} 1982 1983/// dumpLayout - Dump the vtable layout. 1984void VTableBuilder::dumpLayout(llvm::raw_ostream& Out) { 1985 1986 if (isBuildingConstructorVTable()) { 1987 Out << "Construction vtable for ('"; 1988 Out << MostDerivedClass->getQualifiedNameAsString() << "', "; 1989 // FIXME: Don't use / 8 . 1990 Out << MostDerivedClassOffset / 8 << ") in '"; 1991 Out << LayoutClass->getQualifiedNameAsString(); 1992 } else { 1993 Out << "Vtable for '"; 1994 Out << MostDerivedClass->getQualifiedNameAsString(); 1995 } 1996 Out << "' (" << Components.size() << " entries).\n"; 1997 1998 // Iterate through the address points and insert them into a new map where 1999 // they are keyed by the index and not the base object. 2000 // Since an address point can be shared by multiple subobjects, we use an 2001 // STL multimap. 2002 std::multimap<uint64_t, BaseSubobject> AddressPointsByIndex; 2003 for (AddressPointsMapTy::const_iterator I = AddressPoints.begin(), 2004 E = AddressPoints.end(); I != E; ++I) { 2005 const BaseSubobject& Base = I->first; 2006 uint64_t Index = I->second; 2007 2008 AddressPointsByIndex.insert(std::make_pair(Index, Base)); 2009 } 2010 2011 for (unsigned I = 0, E = Components.size(); I != E; ++I) { 2012 uint64_t Index = I; 2013 2014 Out << llvm::format("%4d | ", I); 2015 2016 const VTableComponent &Component = Components[I]; 2017 2018 // Dump the component. 2019 switch (Component.getKind()) { 2020 2021 case VTableComponent::CK_VCallOffset: 2022 Out << "vcall_offset (" << Component.getVCallOffset() << ")"; 2023 break; 2024 2025 case VTableComponent::CK_VBaseOffset: 2026 Out << "vbase_offset (" << Component.getVBaseOffset() << ")"; 2027 break; 2028 2029 case VTableComponent::CK_OffsetToTop: 2030 Out << "offset_to_top (" << Component.getOffsetToTop() << ")"; 2031 break; 2032 2033 case VTableComponent::CK_RTTI: 2034 Out << Component.getRTTIDecl()->getQualifiedNameAsString() << " RTTI"; 2035 break; 2036 2037 case VTableComponent::CK_FunctionPointer: { 2038 const CXXMethodDecl *MD = Component.getFunctionDecl(); 2039 2040 std::string Str = 2041 PredefinedExpr::ComputeName(PredefinedExpr::PrettyFunctionNoVirtual, 2042 MD); 2043 Out << Str; 2044 if (MD->isPure()) 2045 Out << " [pure]"; 2046 2047 ThunkInfo Thunk = VTableThunks.lookup(I); 2048 if (!Thunk.isEmpty()) { 2049 // If this function pointer has a return adjustment, dump it. 2050 if (!Thunk.Return.isEmpty()) { 2051 Out << "\n [return adjustment: "; 2052 Out << Thunk.Return.NonVirtual << " non-virtual"; 2053 2054 if (Thunk.Return.VBaseOffsetOffset) { 2055 Out << ", " << Thunk.Return.VBaseOffsetOffset; 2056 Out << " vbase offset offset"; 2057 } 2058 2059 Out << ']'; 2060 } 2061 2062 // If this function pointer has a 'this' pointer adjustment, dump it. 2063 if (!Thunk.This.isEmpty()) { 2064 Out << "\n [this adjustment: "; 2065 Out << Thunk.This.NonVirtual << " non-virtual"; 2066 2067 if (Thunk.This.VCallOffsetOffset) { 2068 Out << ", " << Thunk.This.VCallOffsetOffset; 2069 Out << " vcall offset offset"; 2070 } 2071 2072 Out << ']'; 2073 } 2074 } 2075 2076 break; 2077 } 2078 2079 case VTableComponent::CK_CompleteDtorPointer: 2080 case VTableComponent::CK_DeletingDtorPointer: { 2081 bool IsComplete = 2082 Component.getKind() == VTableComponent::CK_CompleteDtorPointer; 2083 2084 const CXXDestructorDecl *DD = Component.getDestructorDecl(); 2085 2086 Out << DD->getQualifiedNameAsString(); 2087 if (IsComplete) 2088 Out << "() [complete]"; 2089 else 2090 Out << "() [deleting]"; 2091 2092 if (DD->isPure()) 2093 Out << " [pure]"; 2094 2095 ThunkInfo Thunk = VTableThunks.lookup(I); 2096 if (!Thunk.isEmpty()) { 2097 // If this destructor has a 'this' pointer adjustment, dump it. 2098 if (!Thunk.This.isEmpty()) { 2099 Out << "\n [this adjustment: "; 2100 Out << Thunk.This.NonVirtual << " non-virtual"; 2101 2102 if (Thunk.This.VCallOffsetOffset) { 2103 Out << ", " << Thunk.This.VCallOffsetOffset; 2104 Out << " vcall offset offset"; 2105 } 2106 2107 Out << ']'; 2108 } 2109 } 2110 2111 break; 2112 } 2113 2114 case VTableComponent::CK_UnusedFunctionPointer: { 2115 const CXXMethodDecl *MD = Component.getUnusedFunctionDecl(); 2116 2117 std::string Str = 2118 PredefinedExpr::ComputeName(PredefinedExpr::PrettyFunctionNoVirtual, 2119 MD); 2120 Out << "[unused] " << Str; 2121 if (MD->isPure()) 2122 Out << " [pure]"; 2123 } 2124 2125 } 2126 2127 Out << '\n'; 2128 2129 // Dump the next address point. 2130 uint64_t NextIndex = Index + 1; 2131 if (AddressPointsByIndex.count(NextIndex)) { 2132 if (AddressPointsByIndex.count(NextIndex) == 1) { 2133 const BaseSubobject &Base = 2134 AddressPointsByIndex.find(NextIndex)->second; 2135 2136 // FIXME: Instead of dividing by 8, we should be using CharUnits. 2137 Out << " -- (" << Base.getBase()->getQualifiedNameAsString(); 2138 Out << ", " << Base.getBaseOffset().getQuantity(); 2139 Out << ") vtable address --\n"; 2140 } else { 2141 CharUnits BaseOffset = 2142 AddressPointsByIndex.lower_bound(NextIndex)->second.getBaseOffset(); 2143 2144 // We store the class names in a set to get a stable order. 2145 std::set<std::string> ClassNames; 2146 for (std::multimap<uint64_t, BaseSubobject>::const_iterator I = 2147 AddressPointsByIndex.lower_bound(NextIndex), E = 2148 AddressPointsByIndex.upper_bound(NextIndex); I != E; ++I) { 2149 assert(I->second.getBaseOffset() == BaseOffset && 2150 "Invalid base offset!"); 2151 const CXXRecordDecl *RD = I->second.getBase(); 2152 ClassNames.insert(RD->getQualifiedNameAsString()); 2153 } 2154 2155 for (std::set<std::string>::const_iterator I = ClassNames.begin(), 2156 E = ClassNames.end(); I != E; ++I) { 2157 Out << " -- (" << *I; 2158 Out << ", " << BaseOffset.getQuantity() << ") vtable address --\n"; 2159 } 2160 } 2161 } 2162 } 2163 2164 Out << '\n'; 2165 2166 if (isBuildingConstructorVTable()) 2167 return; 2168 2169 if (MostDerivedClass->getNumVBases()) { 2170 // We store the virtual base class names and their offsets in a map to get 2171 // a stable order. 2172 2173 std::map<std::string, int64_t> ClassNamesAndOffsets; 2174 for (VBaseOffsetOffsetsMapTy::const_iterator I = VBaseOffsetOffsets.begin(), 2175 E = VBaseOffsetOffsets.end(); I != E; ++I) { 2176 std::string ClassName = I->first->getQualifiedNameAsString(); 2177 int64_t OffsetOffset = I->second; 2178 ClassNamesAndOffsets.insert(std::make_pair(ClassName, OffsetOffset)); 2179 } 2180 2181 Out << "Virtual base offset offsets for '"; 2182 Out << MostDerivedClass->getQualifiedNameAsString() << "' ("; 2183 Out << ClassNamesAndOffsets.size(); 2184 Out << (ClassNamesAndOffsets.size() == 1 ? " entry" : " entries") << ").\n"; 2185 2186 for (std::map<std::string, int64_t>::const_iterator I = 2187 ClassNamesAndOffsets.begin(), E = ClassNamesAndOffsets.end(); 2188 I != E; ++I) 2189 Out << " " << I->first << " | " << I->second << '\n'; 2190 2191 Out << "\n"; 2192 } 2193 2194 if (!Thunks.empty()) { 2195 // We store the method names in a map to get a stable order. 2196 std::map<std::string, const CXXMethodDecl *> MethodNamesAndDecls; 2197 2198 for (ThunksMapTy::const_iterator I = Thunks.begin(), E = Thunks.end(); 2199 I != E; ++I) { 2200 const CXXMethodDecl *MD = I->first; 2201 std::string MethodName = 2202 PredefinedExpr::ComputeName(PredefinedExpr::PrettyFunctionNoVirtual, 2203 MD); 2204 2205 MethodNamesAndDecls.insert(std::make_pair(MethodName, MD)); 2206 } 2207 2208 for (std::map<std::string, const CXXMethodDecl *>::const_iterator I = 2209 MethodNamesAndDecls.begin(), E = MethodNamesAndDecls.end(); 2210 I != E; ++I) { 2211 const std::string &MethodName = I->first; 2212 const CXXMethodDecl *MD = I->second; 2213 2214 ThunkInfoVectorTy ThunksVector = Thunks[MD]; 2215 std::sort(ThunksVector.begin(), ThunksVector.end()); 2216 2217 Out << "Thunks for '" << MethodName << "' (" << ThunksVector.size(); 2218 Out << (ThunksVector.size() == 1 ? " entry" : " entries") << ").\n"; 2219 2220 for (unsigned I = 0, E = ThunksVector.size(); I != E; ++I) { 2221 const ThunkInfo &Thunk = ThunksVector[I]; 2222 2223 Out << llvm::format("%4d | ", I); 2224 2225 // If this function pointer has a return pointer adjustment, dump it. 2226 if (!Thunk.Return.isEmpty()) { 2227 Out << "return adjustment: " << Thunk.This.NonVirtual; 2228 Out << " non-virtual"; 2229 if (Thunk.Return.VBaseOffsetOffset) { 2230 Out << ", " << Thunk.Return.VBaseOffsetOffset; 2231 Out << " vbase offset offset"; 2232 } 2233 2234 if (!Thunk.This.isEmpty()) 2235 Out << "\n "; 2236 } 2237 2238 // If this function pointer has a 'this' pointer adjustment, dump it. 2239 if (!Thunk.This.isEmpty()) { 2240 Out << "this adjustment: "; 2241 Out << Thunk.This.NonVirtual << " non-virtual"; 2242 2243 if (Thunk.This.VCallOffsetOffset) { 2244 Out << ", " << Thunk.This.VCallOffsetOffset; 2245 Out << " vcall offset offset"; 2246 } 2247 } 2248 2249 Out << '\n'; 2250 } 2251 2252 Out << '\n'; 2253 2254 } 2255 } 2256} 2257 2258} 2259 2260static void 2261CollectPrimaryBases(const CXXRecordDecl *RD, ASTContext &Context, 2262 VTableBuilder::PrimaryBasesSetVectorTy &PrimaryBases) { 2263 while (RD) { 2264 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); 2265 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase(); 2266 if (PrimaryBase) 2267 PrimaryBases.insert(PrimaryBase); 2268 2269 RD = PrimaryBase; 2270 } 2271} 2272 2273void CodeGenVTables::ComputeMethodVTableIndices(const CXXRecordDecl *RD) { 2274 2275 // Itanium C++ ABI 2.5.2: 2276 // The order of the virtual function pointers in a virtual table is the 2277 // order of declaration of the corresponding member functions in the class. 2278 // 2279 // There is an entry for any virtual function declared in a class, 2280 // whether it is a new function or overrides a base class function, 2281 // unless it overrides a function from the primary base, and conversion 2282 // between their return types does not require an adjustment. 2283 2284 int64_t CurrentIndex = 0; 2285 2286 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD); 2287 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase(); 2288 2289 if (PrimaryBase) { 2290 assert(PrimaryBase->isDefinition() && 2291 "Should have the definition decl of the primary base!"); 2292 2293 // Since the record decl shares its vtable pointer with the primary base 2294 // we need to start counting at the end of the primary base's vtable. 2295 CurrentIndex = getNumVirtualFunctionPointers(PrimaryBase); 2296 } 2297 2298 // Collect all the primary bases, so we can check whether methods override 2299 // a method from the base. 2300 VTableBuilder::PrimaryBasesSetVectorTy PrimaryBases; 2301 CollectPrimaryBases(RD, CGM.getContext(), PrimaryBases); 2302 2303 const CXXDestructorDecl *ImplicitVirtualDtor = 0; 2304 2305 for (CXXRecordDecl::method_iterator i = RD->method_begin(), 2306 e = RD->method_end(); i != e; ++i) { 2307 const CXXMethodDecl *MD = *i; 2308 2309 // We only want virtual methods. 2310 if (!MD->isVirtual()) 2311 continue; 2312 2313 // Check if this method overrides a method in the primary base. 2314 if (const CXXMethodDecl *OverriddenMD = 2315 FindNearestOverriddenMethod(MD, PrimaryBases)) { 2316 // Check if converting from the return type of the method to the 2317 // return type of the overridden method requires conversion. 2318 if (ComputeReturnAdjustmentBaseOffset(CGM.getContext(), MD, 2319 OverriddenMD).isEmpty()) { 2320 // This index is shared between the index in the vtable of the primary 2321 // base class. 2322 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) { 2323 const CXXDestructorDecl *OverriddenDD = 2324 cast<CXXDestructorDecl>(OverriddenMD); 2325 2326 // Add both the complete and deleting entries. 2327 MethodVTableIndices[GlobalDecl(DD, Dtor_Complete)] = 2328 getMethodVTableIndex(GlobalDecl(OverriddenDD, Dtor_Complete)); 2329 MethodVTableIndices[GlobalDecl(DD, Dtor_Deleting)] = 2330 getMethodVTableIndex(GlobalDecl(OverriddenDD, Dtor_Deleting)); 2331 } else { 2332 MethodVTableIndices[MD] = getMethodVTableIndex(OverriddenMD); 2333 } 2334 2335 // We don't need to add an entry for this method. 2336 continue; 2337 } 2338 } 2339 2340 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) { 2341 if (MD->isImplicit()) { 2342 assert(!ImplicitVirtualDtor && 2343 "Did already see an implicit virtual dtor!"); 2344 ImplicitVirtualDtor = DD; 2345 continue; 2346 } 2347 2348 // Add the complete dtor. 2349 MethodVTableIndices[GlobalDecl(DD, Dtor_Complete)] = CurrentIndex++; 2350 2351 // Add the deleting dtor. 2352 MethodVTableIndices[GlobalDecl(DD, Dtor_Deleting)] = CurrentIndex++; 2353 } else { 2354 // Add the entry. 2355 MethodVTableIndices[MD] = CurrentIndex++; 2356 } 2357 } 2358 2359 if (ImplicitVirtualDtor) { 2360 // Itanium C++ ABI 2.5.2: 2361 // If a class has an implicitly-defined virtual destructor, 2362 // its entries come after the declared virtual function pointers. 2363 2364 // Add the complete dtor. 2365 MethodVTableIndices[GlobalDecl(ImplicitVirtualDtor, Dtor_Complete)] = 2366 CurrentIndex++; 2367 2368 // Add the deleting dtor. 2369 MethodVTableIndices[GlobalDecl(ImplicitVirtualDtor, Dtor_Deleting)] = 2370 CurrentIndex++; 2371 } 2372 2373 NumVirtualFunctionPointers[RD] = CurrentIndex; 2374} 2375 2376bool CodeGenVTables::ShouldEmitVTableInThisTU(const CXXRecordDecl *RD) { 2377 assert(RD->isDynamicClass() && "Non dynamic classes have no VTable."); 2378 2379 TemplateSpecializationKind TSK = RD->getTemplateSpecializationKind(); 2380 if (TSK == TSK_ExplicitInstantiationDeclaration) 2381 return false; 2382 2383 const CXXMethodDecl *KeyFunction = CGM.getContext().getKeyFunction(RD); 2384 if (!KeyFunction) 2385 return true; 2386 2387 // Itanium C++ ABI, 5.2.6 Instantiated Templates: 2388 // An instantiation of a class template requires: 2389 // - In the object where instantiated, the virtual table... 2390 if (TSK == TSK_ImplicitInstantiation || 2391 TSK == TSK_ExplicitInstantiationDefinition) 2392 return true; 2393 2394 // If we're building with optimization, we always emit VTables since that 2395 // allows for virtual function calls to be devirtualized. 2396 // (We don't want to do this in -fapple-kext mode however). 2397 if (CGM.getCodeGenOpts().OptimizationLevel && !CGM.getLangOptions().AppleKext) 2398 return true; 2399 2400 return KeyFunction->hasBody(); 2401} 2402 2403uint64_t CodeGenVTables::getNumVirtualFunctionPointers(const CXXRecordDecl *RD) { 2404 llvm::DenseMap<const CXXRecordDecl *, uint64_t>::iterator I = 2405 NumVirtualFunctionPointers.find(RD); 2406 if (I != NumVirtualFunctionPointers.end()) 2407 return I->second; 2408 2409 ComputeMethodVTableIndices(RD); 2410 2411 I = NumVirtualFunctionPointers.find(RD); 2412 assert(I != NumVirtualFunctionPointers.end() && "Did not find entry!"); 2413 return I->second; 2414} 2415 2416uint64_t CodeGenVTables::getMethodVTableIndex(GlobalDecl GD) { 2417 MethodVTableIndicesTy::iterator I = MethodVTableIndices.find(GD); 2418 if (I != MethodVTableIndices.end()) 2419 return I->second; 2420 2421 const CXXRecordDecl *RD = cast<CXXMethodDecl>(GD.getDecl())->getParent(); 2422 2423 ComputeMethodVTableIndices(RD); 2424 2425 I = MethodVTableIndices.find(GD); 2426 assert(I != MethodVTableIndices.end() && "Did not find index!"); 2427 return I->second; 2428} 2429 2430int64_t CodeGenVTables::getVirtualBaseOffsetOffset(const CXXRecordDecl *RD, 2431 const CXXRecordDecl *VBase) { 2432 ClassPairTy ClassPair(RD, VBase); 2433 2434 VirtualBaseClassOffsetOffsetsMapTy::iterator I = 2435 VirtualBaseClassOffsetOffsets.find(ClassPair); 2436 if (I != VirtualBaseClassOffsetOffsets.end()) 2437 return I->second; 2438 2439 VCallAndVBaseOffsetBuilder Builder(RD, RD, /*FinalOverriders=*/0, 2440 BaseSubobject(RD, CharUnits::Zero()), 2441 /*BaseIsVirtual=*/false, 2442 /*OffsetInLayoutClass=*/0); 2443 2444 for (VCallAndVBaseOffsetBuilder::VBaseOffsetOffsetsMapTy::const_iterator I = 2445 Builder.getVBaseOffsetOffsets().begin(), 2446 E = Builder.getVBaseOffsetOffsets().end(); I != E; ++I) { 2447 // Insert all types. 2448 ClassPairTy ClassPair(RD, I->first); 2449 2450 VirtualBaseClassOffsetOffsets.insert(std::make_pair(ClassPair, I->second)); 2451 } 2452 2453 I = VirtualBaseClassOffsetOffsets.find(ClassPair); 2454 assert(I != VirtualBaseClassOffsetOffsets.end() && "Did not find index!"); 2455 2456 return I->second; 2457} 2458 2459uint64_t 2460CodeGenVTables::getAddressPoint(BaseSubobject Base, const CXXRecordDecl *RD) { 2461 assert(AddressPoints.count(std::make_pair(RD, Base)) && 2462 "Did not find address point!"); 2463 2464 uint64_t AddressPoint = AddressPoints.lookup(std::make_pair(RD, Base)); 2465 assert(AddressPoint && "Address point must not be zero!"); 2466 2467 return AddressPoint; 2468} 2469 2470llvm::Constant *CodeGenModule::GetAddrOfThunk(GlobalDecl GD, 2471 const ThunkInfo &Thunk) { 2472 const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); 2473 2474 // Compute the mangled name. 2475 llvm::SmallString<256> Name; 2476 llvm::raw_svector_ostream Out(Name); 2477 if (const CXXDestructorDecl* DD = dyn_cast<CXXDestructorDecl>(MD)) 2478 getCXXABI().getMangleContext().mangleCXXDtorThunk(DD, GD.getDtorType(), 2479 Thunk.This, Out); 2480 else 2481 getCXXABI().getMangleContext().mangleThunk(MD, Thunk, Out); 2482 Out.flush(); 2483 2484 const llvm::Type *Ty = getTypes().GetFunctionTypeForVTable(GD); 2485 return GetOrCreateLLVMFunction(Name, Ty, GD, /*ForVTable=*/true); 2486} 2487 2488static llvm::Value *PerformTypeAdjustment(CodeGenFunction &CGF, 2489 llvm::Value *Ptr, 2490 int64_t NonVirtualAdjustment, 2491 int64_t VirtualAdjustment) { 2492 if (!NonVirtualAdjustment && !VirtualAdjustment) 2493 return Ptr; 2494 2495 const llvm::Type *Int8PtrTy = 2496 llvm::Type::getInt8PtrTy(CGF.getLLVMContext()); 2497 2498 llvm::Value *V = CGF.Builder.CreateBitCast(Ptr, Int8PtrTy); 2499 2500 if (NonVirtualAdjustment) { 2501 // Do the non-virtual adjustment. 2502 V = CGF.Builder.CreateConstInBoundsGEP1_64(V, NonVirtualAdjustment); 2503 } 2504 2505 if (VirtualAdjustment) { 2506 const llvm::Type *PtrDiffTy = 2507 CGF.ConvertType(CGF.getContext().getPointerDiffType()); 2508 2509 // Do the virtual adjustment. 2510 llvm::Value *VTablePtrPtr = 2511 CGF.Builder.CreateBitCast(V, Int8PtrTy->getPointerTo()); 2512 2513 llvm::Value *VTablePtr = CGF.Builder.CreateLoad(VTablePtrPtr); 2514 2515 llvm::Value *OffsetPtr = 2516 CGF.Builder.CreateConstInBoundsGEP1_64(VTablePtr, VirtualAdjustment); 2517 2518 OffsetPtr = CGF.Builder.CreateBitCast(OffsetPtr, PtrDiffTy->getPointerTo()); 2519 2520 // Load the adjustment offset from the vtable. 2521 llvm::Value *Offset = CGF.Builder.CreateLoad(OffsetPtr); 2522 2523 // Adjust our pointer. 2524 V = CGF.Builder.CreateInBoundsGEP(V, Offset); 2525 } 2526 2527 // Cast back to the original type. 2528 return CGF.Builder.CreateBitCast(V, Ptr->getType()); 2529} 2530 2531static void setThunkVisibility(CodeGenModule &CGM, const CXXMethodDecl *MD, 2532 const ThunkInfo &Thunk, llvm::Function *Fn) { 2533 CGM.setGlobalVisibility(Fn, MD); 2534 2535 if (!CGM.getCodeGenOpts().HiddenWeakVTables) 2536 return; 2537 2538 // If the thunk has weak/linkonce linkage, but the function must be 2539 // emitted in every translation unit that references it, then we can 2540 // emit its thunks with hidden visibility, since its thunks must be 2541 // emitted when the function is. 2542 2543 // This follows CodeGenModule::setTypeVisibility; see the comments 2544 // there for explanation. 2545 2546 if ((Fn->getLinkage() != llvm::GlobalVariable::LinkOnceODRLinkage && 2547 Fn->getLinkage() != llvm::GlobalVariable::WeakODRLinkage) || 2548 Fn->getVisibility() != llvm::GlobalVariable::DefaultVisibility) 2549 return; 2550 2551 if (MD->getExplicitVisibility()) 2552 return; 2553 2554 switch (MD->getTemplateSpecializationKind()) { 2555 case TSK_ExplicitInstantiationDefinition: 2556 case TSK_ExplicitInstantiationDeclaration: 2557 return; 2558 2559 case TSK_Undeclared: 2560 break; 2561 2562 case TSK_ExplicitSpecialization: 2563 case TSK_ImplicitInstantiation: 2564 if (!CGM.getCodeGenOpts().HiddenWeakTemplateVTables) 2565 return; 2566 break; 2567 } 2568 2569 // If there's an explicit definition, and that definition is 2570 // out-of-line, then we can't assume that all users will have a 2571 // definition to emit. 2572 const FunctionDecl *Def = 0; 2573 if (MD->hasBody(Def) && Def->isOutOfLine()) 2574 return; 2575 2576 Fn->setVisibility(llvm::GlobalValue::HiddenVisibility); 2577} 2578 2579#ifndef NDEBUG 2580static bool similar(const ABIArgInfo &infoL, CanQualType typeL, 2581 const ABIArgInfo &infoR, CanQualType typeR) { 2582 return (infoL.getKind() == infoR.getKind() && 2583 (typeL == typeR || 2584 (isa<PointerType>(typeL) && isa<PointerType>(typeR)) || 2585 (isa<ReferenceType>(typeL) && isa<ReferenceType>(typeR)))); 2586} 2587#endif 2588 2589void CodeGenFunction::GenerateThunk(llvm::Function *Fn, 2590 const CGFunctionInfo &FnInfo, 2591 GlobalDecl GD, const ThunkInfo &Thunk) { 2592 const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); 2593 const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>(); 2594 QualType ResultType = FPT->getResultType(); 2595 QualType ThisType = MD->getThisType(getContext()); 2596 2597 FunctionArgList FunctionArgs; 2598 2599 // FIXME: It would be nice if more of this code could be shared with 2600 // CodeGenFunction::GenerateCode. 2601 2602 // Create the implicit 'this' parameter declaration. 2603 CurGD = GD; 2604 CGM.getCXXABI().BuildInstanceFunctionParams(*this, ResultType, FunctionArgs); 2605 2606 // Add the rest of the parameters. 2607 for (FunctionDecl::param_const_iterator I = MD->param_begin(), 2608 E = MD->param_end(); I != E; ++I) { 2609 ParmVarDecl *Param = *I; 2610 2611 FunctionArgs.push_back(Param); 2612 } 2613 2614 StartFunction(GlobalDecl(), ResultType, Fn, FnInfo, FunctionArgs, 2615 SourceLocation()); 2616 2617 CGM.getCXXABI().EmitInstanceFunctionProlog(*this); 2618 2619 // Adjust the 'this' pointer if necessary. 2620 llvm::Value *AdjustedThisPtr = 2621 PerformTypeAdjustment(*this, LoadCXXThis(), 2622 Thunk.This.NonVirtual, 2623 Thunk.This.VCallOffsetOffset); 2624 2625 CallArgList CallArgs; 2626 2627 // Add our adjusted 'this' pointer. 2628 CallArgs.push_back(std::make_pair(RValue::get(AdjustedThisPtr), ThisType)); 2629 2630 // Add the rest of the parameters. 2631 for (FunctionDecl::param_const_iterator I = MD->param_begin(), 2632 E = MD->param_end(); I != E; ++I) { 2633 ParmVarDecl *param = *I; 2634 EmitDelegateCallArg(CallArgs, param); 2635 } 2636 2637 // Get our callee. 2638 const llvm::Type *Ty = 2639 CGM.getTypes().GetFunctionType(CGM.getTypes().getFunctionInfo(GD), 2640 FPT->isVariadic()); 2641 llvm::Value *Callee = CGM.GetAddrOfFunction(GD, Ty, /*ForVTable=*/true); 2642 2643#ifndef NDEBUG 2644 const CGFunctionInfo &CallFnInfo = 2645 CGM.getTypes().getFunctionInfo(ResultType, CallArgs, FPT->getExtInfo()); 2646 assert(CallFnInfo.getRegParm() == FnInfo.getRegParm() && 2647 CallFnInfo.isNoReturn() == FnInfo.isNoReturn() && 2648 CallFnInfo.getCallingConvention() == FnInfo.getCallingConvention()); 2649 assert(similar(CallFnInfo.getReturnInfo(), CallFnInfo.getReturnType(), 2650 FnInfo.getReturnInfo(), FnInfo.getReturnType())); 2651 assert(CallFnInfo.arg_size() == FnInfo.arg_size()); 2652 for (unsigned i = 0, e = FnInfo.arg_size(); i != e; ++i) 2653 assert(similar(CallFnInfo.arg_begin()[i].info, 2654 CallFnInfo.arg_begin()[i].type, 2655 FnInfo.arg_begin()[i].info, FnInfo.arg_begin()[i].type)); 2656#endif 2657 2658 // Determine whether we have a return value slot to use. 2659 ReturnValueSlot Slot; 2660 if (!ResultType->isVoidType() && 2661 FnInfo.getReturnInfo().getKind() == ABIArgInfo::Indirect && 2662 hasAggregateLLVMType(CurFnInfo->getReturnType())) 2663 Slot = ReturnValueSlot(ReturnValue, ResultType.isVolatileQualified()); 2664 2665 // Now emit our call. 2666 RValue RV = EmitCall(FnInfo, Callee, Slot, CallArgs, MD); 2667 2668 if (!Thunk.Return.isEmpty()) { 2669 // Emit the return adjustment. 2670 bool NullCheckValue = !ResultType->isReferenceType(); 2671 2672 llvm::BasicBlock *AdjustNull = 0; 2673 llvm::BasicBlock *AdjustNotNull = 0; 2674 llvm::BasicBlock *AdjustEnd = 0; 2675 2676 llvm::Value *ReturnValue = RV.getScalarVal(); 2677 2678 if (NullCheckValue) { 2679 AdjustNull = createBasicBlock("adjust.null"); 2680 AdjustNotNull = createBasicBlock("adjust.notnull"); 2681 AdjustEnd = createBasicBlock("adjust.end"); 2682 2683 llvm::Value *IsNull = Builder.CreateIsNull(ReturnValue); 2684 Builder.CreateCondBr(IsNull, AdjustNull, AdjustNotNull); 2685 EmitBlock(AdjustNotNull); 2686 } 2687 2688 ReturnValue = PerformTypeAdjustment(*this, ReturnValue, 2689 Thunk.Return.NonVirtual, 2690 Thunk.Return.VBaseOffsetOffset); 2691 2692 if (NullCheckValue) { 2693 Builder.CreateBr(AdjustEnd); 2694 EmitBlock(AdjustNull); 2695 Builder.CreateBr(AdjustEnd); 2696 EmitBlock(AdjustEnd); 2697 2698 llvm::PHINode *PHI = Builder.CreatePHI(ReturnValue->getType()); 2699 PHI->reserveOperandSpace(2); 2700 PHI->addIncoming(ReturnValue, AdjustNotNull); 2701 PHI->addIncoming(llvm::Constant::getNullValue(ReturnValue->getType()), 2702 AdjustNull); 2703 ReturnValue = PHI; 2704 } 2705 2706 RV = RValue::get(ReturnValue); 2707 } 2708 2709 if (!ResultType->isVoidType() && Slot.isNull()) 2710 CGM.getCXXABI().EmitReturnFromThunk(*this, RV, ResultType); 2711 2712 FinishFunction(); 2713 2714 // Set the right linkage. 2715 CGM.setFunctionLinkage(MD, Fn); 2716 2717 // Set the right visibility. 2718 setThunkVisibility(CGM, MD, Thunk, Fn); 2719} 2720 2721void CodeGenVTables::EmitThunk(GlobalDecl GD, const ThunkInfo &Thunk, 2722 bool UseAvailableExternallyLinkage) 2723{ 2724 const CGFunctionInfo &FnInfo = CGM.getTypes().getFunctionInfo(GD); 2725 2726 // FIXME: re-use FnInfo in this computation. 2727 llvm::Constant *Entry = CGM.GetAddrOfThunk(GD, Thunk); 2728 2729 // Strip off a bitcast if we got one back. 2730 if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(Entry)) { 2731 assert(CE->getOpcode() == llvm::Instruction::BitCast); 2732 Entry = CE->getOperand(0); 2733 } 2734 2735 // There's already a declaration with the same name, check if it has the same 2736 // type or if we need to replace it. 2737 if (cast<llvm::GlobalValue>(Entry)->getType()->getElementType() != 2738 CGM.getTypes().GetFunctionTypeForVTable(GD)) { 2739 llvm::GlobalValue *OldThunkFn = cast<llvm::GlobalValue>(Entry); 2740 2741 // If the types mismatch then we have to rewrite the definition. 2742 assert(OldThunkFn->isDeclaration() && 2743 "Shouldn't replace non-declaration"); 2744 2745 // Remove the name from the old thunk function and get a new thunk. 2746 OldThunkFn->setName(llvm::StringRef()); 2747 Entry = CGM.GetAddrOfThunk(GD, Thunk); 2748 2749 // If needed, replace the old thunk with a bitcast. 2750 if (!OldThunkFn->use_empty()) { 2751 llvm::Constant *NewPtrForOldDecl = 2752 llvm::ConstantExpr::getBitCast(Entry, OldThunkFn->getType()); 2753 OldThunkFn->replaceAllUsesWith(NewPtrForOldDecl); 2754 } 2755 2756 // Remove the old thunk. 2757 OldThunkFn->eraseFromParent(); 2758 } 2759 2760 llvm::Function *ThunkFn = cast<llvm::Function>(Entry); 2761 2762 if (!ThunkFn->isDeclaration()) { 2763 if (UseAvailableExternallyLinkage) { 2764 // There is already a thunk emitted for this function, do nothing. 2765 return; 2766 } 2767 2768 // If a function has a body, it should have available_externally linkage. 2769 assert(ThunkFn->hasAvailableExternallyLinkage() && 2770 "Function should have available_externally linkage!"); 2771 2772 // Change the linkage. 2773 CGM.setFunctionLinkage(cast<CXXMethodDecl>(GD.getDecl()), ThunkFn); 2774 return; 2775 } 2776 2777 // Actually generate the thunk body. 2778 CodeGenFunction(CGM).GenerateThunk(ThunkFn, FnInfo, GD, Thunk); 2779 2780 if (UseAvailableExternallyLinkage) 2781 ThunkFn->setLinkage(llvm::GlobalValue::AvailableExternallyLinkage); 2782} 2783 2784void CodeGenVTables::MaybeEmitThunkAvailableExternally(GlobalDecl GD, 2785 const ThunkInfo &Thunk) { 2786 // We only want to do this when building with optimizations. 2787 if (!CGM.getCodeGenOpts().OptimizationLevel) 2788 return; 2789 2790 // We can't emit thunks for member functions with incomplete types. 2791 const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); 2792 if (CGM.getTypes().VerifyFuncTypeComplete(MD->getType().getTypePtr())) 2793 return; 2794 2795 EmitThunk(GD, Thunk, /*UseAvailableExternallyLinkage=*/true); 2796} 2797 2798void CodeGenVTables::EmitThunks(GlobalDecl GD) 2799{ 2800 const CXXMethodDecl *MD = 2801 cast<CXXMethodDecl>(GD.getDecl())->getCanonicalDecl(); 2802 2803 // We don't need to generate thunks for the base destructor. 2804 if (isa<CXXDestructorDecl>(MD) && GD.getDtorType() == Dtor_Base) 2805 return; 2806 2807 const CXXRecordDecl *RD = MD->getParent(); 2808 2809 // Compute VTable related info for this class. 2810 ComputeVTableRelatedInformation(RD, false); 2811 2812 ThunksMapTy::const_iterator I = Thunks.find(MD); 2813 if (I == Thunks.end()) { 2814 // We did not find a thunk for this method. 2815 return; 2816 } 2817 2818 const ThunkInfoVectorTy &ThunkInfoVector = I->second; 2819 for (unsigned I = 0, E = ThunkInfoVector.size(); I != E; ++I) 2820 EmitThunk(GD, ThunkInfoVector[I], /*UseAvailableExternallyLinkage=*/false); 2821} 2822 2823void CodeGenVTables::ComputeVTableRelatedInformation(const CXXRecordDecl *RD, 2824 bool RequireVTable) { 2825 VTableLayoutData &Entry = VTableLayoutMap[RD]; 2826 2827 // We may need to generate a definition for this vtable. 2828 if (RequireVTable && !Entry.getInt()) { 2829 if (ShouldEmitVTableInThisTU(RD)) 2830 CGM.DeferredVTables.push_back(RD); 2831 2832 Entry.setInt(true); 2833 } 2834 2835 // Check if we've computed this information before. 2836 if (Entry.getPointer()) 2837 return; 2838 2839 VTableBuilder Builder(*this, RD, 0, /*MostDerivedClassIsVirtual=*/0, RD); 2840 2841 // Add the VTable layout. 2842 uint64_t NumVTableComponents = Builder.getNumVTableComponents(); 2843 // -fapple-kext adds an extra entry at end of vtbl. 2844 bool IsAppleKext = CGM.getContext().getLangOptions().AppleKext; 2845 if (IsAppleKext) 2846 NumVTableComponents += 1; 2847 2848 uint64_t *LayoutData = new uint64_t[NumVTableComponents + 1]; 2849 if (IsAppleKext) 2850 LayoutData[NumVTableComponents] = 0; 2851 Entry.setPointer(LayoutData); 2852 2853 // Store the number of components. 2854 LayoutData[0] = NumVTableComponents; 2855 2856 // Store the components. 2857 std::copy(Builder.vtable_components_data_begin(), 2858 Builder.vtable_components_data_end(), 2859 &LayoutData[1]); 2860 2861 // Add the known thunks. 2862 Thunks.insert(Builder.thunks_begin(), Builder.thunks_end()); 2863 2864 // Add the thunks needed in this vtable. 2865 assert(!VTableThunksMap.count(RD) && 2866 "Thunks already exists for this vtable!"); 2867 2868 VTableThunksTy &VTableThunks = VTableThunksMap[RD]; 2869 VTableThunks.append(Builder.vtable_thunks_begin(), 2870 Builder.vtable_thunks_end()); 2871 2872 // Sort them. 2873 std::sort(VTableThunks.begin(), VTableThunks.end()); 2874 2875 // Add the address points. 2876 for (VTableBuilder::AddressPointsMapTy::const_iterator I = 2877 Builder.address_points_begin(), E = Builder.address_points_end(); 2878 I != E; ++I) { 2879 2880 uint64_t &AddressPoint = AddressPoints[std::make_pair(RD, I->first)]; 2881 2882 // Check if we already have the address points for this base. 2883 assert(!AddressPoint && "Address point already exists for this base!"); 2884 2885 AddressPoint = I->second; 2886 } 2887 2888 // If we don't have the vbase information for this class, insert it. 2889 // getVirtualBaseOffsetOffset will compute it separately without computing 2890 // the rest of the vtable related information. 2891 if (!RD->getNumVBases()) 2892 return; 2893 2894 const RecordType *VBaseRT = 2895 RD->vbases_begin()->getType()->getAs<RecordType>(); 2896 const CXXRecordDecl *VBase = cast<CXXRecordDecl>(VBaseRT->getDecl()); 2897 2898 if (VirtualBaseClassOffsetOffsets.count(std::make_pair(RD, VBase))) 2899 return; 2900 2901 for (VTableBuilder::VBaseOffsetOffsetsMapTy::const_iterator I = 2902 Builder.getVBaseOffsetOffsets().begin(), 2903 E = Builder.getVBaseOffsetOffsets().end(); I != E; ++I) { 2904 // Insert all types. 2905 ClassPairTy ClassPair(RD, I->first); 2906 2907 VirtualBaseClassOffsetOffsets.insert(std::make_pair(ClassPair, I->second)); 2908 } 2909} 2910 2911llvm::Constant * 2912CodeGenVTables::CreateVTableInitializer(const CXXRecordDecl *RD, 2913 const uint64_t *Components, 2914 unsigned NumComponents, 2915 const VTableThunksTy &VTableThunks) { 2916 llvm::SmallVector<llvm::Constant *, 64> Inits; 2917 2918 const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGM.getLLVMContext()); 2919 2920 const llvm::Type *PtrDiffTy = 2921 CGM.getTypes().ConvertType(CGM.getContext().getPointerDiffType()); 2922 2923 QualType ClassType = CGM.getContext().getTagDeclType(RD); 2924 llvm::Constant *RTTI = CGM.GetAddrOfRTTIDescriptor(ClassType); 2925 2926 unsigned NextVTableThunkIndex = 0; 2927 2928 llvm::Constant* PureVirtualFn = 0; 2929 2930 for (unsigned I = 0; I != NumComponents; ++I) { 2931 VTableComponent Component = 2932 VTableComponent::getFromOpaqueInteger(Components[I]); 2933 2934 llvm::Constant *Init = 0; 2935 2936 switch (Component.getKind()) { 2937 case VTableComponent::CK_VCallOffset: 2938 Init = llvm::ConstantInt::get(PtrDiffTy, Component.getVCallOffset()); 2939 Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy); 2940 break; 2941 case VTableComponent::CK_VBaseOffset: 2942 Init = llvm::ConstantInt::get(PtrDiffTy, Component.getVBaseOffset()); 2943 Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy); 2944 break; 2945 case VTableComponent::CK_OffsetToTop: 2946 Init = llvm::ConstantInt::get(PtrDiffTy, Component.getOffsetToTop()); 2947 Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy); 2948 break; 2949 case VTableComponent::CK_RTTI: 2950 Init = llvm::ConstantExpr::getBitCast(RTTI, Int8PtrTy); 2951 break; 2952 case VTableComponent::CK_FunctionPointer: 2953 case VTableComponent::CK_CompleteDtorPointer: 2954 case VTableComponent::CK_DeletingDtorPointer: { 2955 GlobalDecl GD; 2956 2957 // Get the right global decl. 2958 switch (Component.getKind()) { 2959 default: 2960 llvm_unreachable("Unexpected vtable component kind"); 2961 case VTableComponent::CK_FunctionPointer: 2962 GD = Component.getFunctionDecl(); 2963 break; 2964 case VTableComponent::CK_CompleteDtorPointer: 2965 GD = GlobalDecl(Component.getDestructorDecl(), Dtor_Complete); 2966 break; 2967 case VTableComponent::CK_DeletingDtorPointer: 2968 GD = GlobalDecl(Component.getDestructorDecl(), Dtor_Deleting); 2969 break; 2970 } 2971 2972 if (cast<CXXMethodDecl>(GD.getDecl())->isPure()) { 2973 // We have a pure virtual member function. 2974 if (!PureVirtualFn) { 2975 const llvm::FunctionType *Ty = 2976 llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()), 2977 /*isVarArg=*/false); 2978 PureVirtualFn = 2979 CGM.CreateRuntimeFunction(Ty, "__cxa_pure_virtual"); 2980 PureVirtualFn = llvm::ConstantExpr::getBitCast(PureVirtualFn, 2981 Int8PtrTy); 2982 } 2983 2984 Init = PureVirtualFn; 2985 } else { 2986 // Check if we should use a thunk. 2987 if (NextVTableThunkIndex < VTableThunks.size() && 2988 VTableThunks[NextVTableThunkIndex].first == I) { 2989 const ThunkInfo &Thunk = VTableThunks[NextVTableThunkIndex].second; 2990 2991 Init = CGM.GetAddrOfThunk(GD, Thunk); 2992 MaybeEmitThunkAvailableExternally(GD, Thunk); 2993 2994 NextVTableThunkIndex++; 2995 } else { 2996 const llvm::Type *Ty = CGM.getTypes().GetFunctionTypeForVTable(GD); 2997 2998 Init = CGM.GetAddrOfFunction(GD, Ty, /*ForVTable=*/true); 2999 } 3000 3001 Init = llvm::ConstantExpr::getBitCast(Init, Int8PtrTy); 3002 } 3003 break; 3004 } 3005 3006 case VTableComponent::CK_UnusedFunctionPointer: 3007 Init = llvm::ConstantExpr::getNullValue(Int8PtrTy); 3008 break; 3009 }; 3010 3011 Inits.push_back(Init); 3012 } 3013 3014 llvm::ArrayType *ArrayType = llvm::ArrayType::get(Int8PtrTy, NumComponents); 3015 return llvm::ConstantArray::get(ArrayType, Inits.data(), Inits.size()); 3016} 3017 3018llvm::GlobalVariable *CodeGenVTables::GetAddrOfVTable(const CXXRecordDecl *RD) { 3019 llvm::SmallString<256> OutName; 3020 llvm::raw_svector_ostream Out(OutName); 3021 CGM.getCXXABI().getMangleContext().mangleCXXVTable(RD, Out); 3022 Out.flush(); 3023 llvm::StringRef Name = OutName.str(); 3024 3025 ComputeVTableRelatedInformation(RD, true); 3026 3027 const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGM.getLLVMContext()); 3028 llvm::ArrayType *ArrayType = 3029 llvm::ArrayType::get(Int8PtrTy, getNumVTableComponents(RD)); 3030 3031 llvm::GlobalVariable *GV = 3032 CGM.CreateOrReplaceCXXRuntimeVariable(Name, ArrayType, 3033 llvm::GlobalValue::ExternalLinkage); 3034 GV->setUnnamedAddr(true); 3035 return GV; 3036} 3037 3038void 3039CodeGenVTables::EmitVTableDefinition(llvm::GlobalVariable *VTable, 3040 llvm::GlobalVariable::LinkageTypes Linkage, 3041 const CXXRecordDecl *RD) { 3042 // Dump the vtable layout if necessary. 3043 if (CGM.getLangOptions().DumpVTableLayouts) { 3044 VTableBuilder Builder(*this, RD, 0, /*MostDerivedClassIsVirtual=*/0, RD); 3045 3046 Builder.dumpLayout(llvm::errs()); 3047 } 3048 3049 assert(VTableThunksMap.count(RD) && 3050 "No thunk status for this record decl!"); 3051 3052 const VTableThunksTy& Thunks = VTableThunksMap[RD]; 3053 3054 // Create and set the initializer. 3055 llvm::Constant *Init = 3056 CreateVTableInitializer(RD, getVTableComponentsData(RD), 3057 getNumVTableComponents(RD), Thunks); 3058 VTable->setInitializer(Init); 3059 3060 // Set the correct linkage. 3061 VTable->setLinkage(Linkage); 3062 3063 // Set the right visibility. 3064 CGM.setTypeVisibility(VTable, RD, CodeGenModule::TVK_ForVTable); 3065} 3066 3067llvm::GlobalVariable * 3068CodeGenVTables::GenerateConstructionVTable(const CXXRecordDecl *RD, 3069 const BaseSubobject &Base, 3070 bool BaseIsVirtual, 3071 llvm::GlobalVariable::LinkageTypes Linkage, 3072 VTableAddressPointsMapTy& AddressPoints) { 3073 VTableBuilder Builder(*this, Base.getBase(), 3074 CGM.getContext().toBits(Base.getBaseOffset()), 3075 /*MostDerivedClassIsVirtual=*/BaseIsVirtual, RD); 3076 3077 // Dump the vtable layout if necessary. 3078 if (CGM.getLangOptions().DumpVTableLayouts) 3079 Builder.dumpLayout(llvm::errs()); 3080 3081 // Add the address points. 3082 AddressPoints.insert(Builder.address_points_begin(), 3083 Builder.address_points_end()); 3084 3085 // Get the mangled construction vtable name. 3086 llvm::SmallString<256> OutName; 3087 llvm::raw_svector_ostream Out(OutName); 3088 CGM.getCXXABI().getMangleContext(). 3089 mangleCXXCtorVTable(RD, Base.getBaseOffset().getQuantity(), Base.getBase(), 3090 Out); 3091 Out.flush(); 3092 llvm::StringRef Name = OutName.str(); 3093 3094 const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGM.getLLVMContext()); 3095 llvm::ArrayType *ArrayType = 3096 llvm::ArrayType::get(Int8PtrTy, Builder.getNumVTableComponents()); 3097 3098 // Create the variable that will hold the construction vtable. 3099 llvm::GlobalVariable *VTable = 3100 CGM.CreateOrReplaceCXXRuntimeVariable(Name, ArrayType, Linkage); 3101 CGM.setTypeVisibility(VTable, RD, CodeGenModule::TVK_ForConstructionVTable); 3102 3103 // V-tables are always unnamed_addr. 3104 VTable->setUnnamedAddr(true); 3105 3106 // Add the thunks. 3107 VTableThunksTy VTableThunks; 3108 VTableThunks.append(Builder.vtable_thunks_begin(), 3109 Builder.vtable_thunks_end()); 3110 3111 // Sort them. 3112 std::sort(VTableThunks.begin(), VTableThunks.end()); 3113 3114 // Create and set the initializer. 3115 llvm::Constant *Init = 3116 CreateVTableInitializer(Base.getBase(), 3117 Builder.vtable_components_data_begin(), 3118 Builder.getNumVTableComponents(), VTableThunks); 3119 VTable->setInitializer(Init); 3120 3121 return VTable; 3122} 3123 3124void 3125CodeGenVTables::GenerateClassData(llvm::GlobalVariable::LinkageTypes Linkage, 3126 const CXXRecordDecl *RD) { 3127 llvm::GlobalVariable *&VTable = VTables[RD]; 3128 if (VTable) { 3129 assert(VTable->getInitializer() && "VTable doesn't have a definition!"); 3130 return; 3131 } 3132 3133 VTable = GetAddrOfVTable(RD); 3134 EmitVTableDefinition(VTable, Linkage, RD); 3135 3136 if (RD->getNumVBases()) { 3137 llvm::GlobalVariable *VTT = GetAddrOfVTT(RD); 3138 EmitVTTDefinition(VTT, Linkage, RD); 3139 } 3140 3141 // If this is the magic class __cxxabiv1::__fundamental_type_info, 3142 // we will emit the typeinfo for the fundamental types. This is the 3143 // same behaviour as GCC. 3144 const DeclContext *DC = RD->getDeclContext(); 3145 if (RD->getIdentifier() && 3146 RD->getIdentifier()->isStr("__fundamental_type_info") && 3147 isa<NamespaceDecl>(DC) && 3148 cast<NamespaceDecl>(DC)->getIdentifier() && 3149 cast<NamespaceDecl>(DC)->getIdentifier()->isStr("__cxxabiv1") && 3150 DC->getParent()->isTranslationUnit()) 3151 CGM.EmitFundamentalRTTIDescriptors(); 3152} 3153