CGVTables.cpp revision fc72420a2245774b5a3f0cd0d7f7527f0f5c84db
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 CharUnits 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 CharUnits 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 CharUnits 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 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 CharUnits 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, CharUnits BaseOffsetInLayoutClass, 1111 const CXXRecordDecl *FirstBaseInPrimaryBaseChain, 1112 CharUnits 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, 1166 MostDerivedClass->getASTContext().toCharUnitsFromBits( 1167 MostDerivedClassOffset), 1168 LayoutClass) { 1169 1170 LayoutVTable(); 1171 } 1172 1173 ThunksMapTy::const_iterator thunks_begin() const { 1174 return Thunks.begin(); 1175 } 1176 1177 ThunksMapTy::const_iterator thunks_end() const { 1178 return Thunks.end(); 1179 } 1180 1181 const VBaseOffsetOffsetsMapTy &getVBaseOffsetOffsets() const { 1182 return VBaseOffsetOffsets; 1183 } 1184 1185 /// getNumVTableComponents - Return the number of components in the vtable 1186 /// currently built. 1187 uint64_t getNumVTableComponents() const { 1188 return Components.size(); 1189 } 1190 1191 const uint64_t *vtable_components_data_begin() const { 1192 return reinterpret_cast<const uint64_t *>(Components.begin()); 1193 } 1194 1195 const uint64_t *vtable_components_data_end() const { 1196 return reinterpret_cast<const uint64_t *>(Components.end()); 1197 } 1198 1199 AddressPointsMapTy::const_iterator address_points_begin() const { 1200 return AddressPoints.begin(); 1201 } 1202 1203 AddressPointsMapTy::const_iterator address_points_end() const { 1204 return AddressPoints.end(); 1205 } 1206 1207 VTableThunksMapTy::const_iterator vtable_thunks_begin() const { 1208 return VTableThunks.begin(); 1209 } 1210 1211 VTableThunksMapTy::const_iterator vtable_thunks_end() const { 1212 return VTableThunks.end(); 1213 } 1214 1215 /// dumpLayout - Dump the vtable layout. 1216 void dumpLayout(llvm::raw_ostream&); 1217}; 1218 1219void VTableBuilder::AddThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk) { 1220 assert(!isBuildingConstructorVTable() && 1221 "Can't add thunks for construction vtable"); 1222 1223 llvm::SmallVector<ThunkInfo, 1> &ThunksVector = Thunks[MD]; 1224 1225 // Check if we have this thunk already. 1226 if (std::find(ThunksVector.begin(), ThunksVector.end(), Thunk) != 1227 ThunksVector.end()) 1228 return; 1229 1230 ThunksVector.push_back(Thunk); 1231} 1232 1233typedef llvm::SmallPtrSet<const CXXMethodDecl *, 8> OverriddenMethodsSetTy; 1234 1235/// ComputeAllOverriddenMethods - Given a method decl, will return a set of all 1236/// the overridden methods that the function decl overrides. 1237static void 1238ComputeAllOverriddenMethods(const CXXMethodDecl *MD, 1239 OverriddenMethodsSetTy& OverriddenMethods) { 1240 assert(MD->isVirtual() && "Method is not virtual!"); 1241 1242 for (CXXMethodDecl::method_iterator I = MD->begin_overridden_methods(), 1243 E = MD->end_overridden_methods(); I != E; ++I) { 1244 const CXXMethodDecl *OverriddenMD = *I; 1245 1246 OverriddenMethods.insert(OverriddenMD); 1247 1248 ComputeAllOverriddenMethods(OverriddenMD, OverriddenMethods); 1249 } 1250} 1251 1252void VTableBuilder::ComputeThisAdjustments() { 1253 // Now go through the method info map and see if any of the methods need 1254 // 'this' pointer adjustments. 1255 for (MethodInfoMapTy::const_iterator I = MethodInfoMap.begin(), 1256 E = MethodInfoMap.end(); I != E; ++I) { 1257 const CXXMethodDecl *MD = I->first; 1258 const MethodInfo &MethodInfo = I->second; 1259 1260 // Ignore adjustments for unused function pointers. 1261 uint64_t VTableIndex = MethodInfo.VTableIndex; 1262 if (Components[VTableIndex].getKind() == 1263 VTableComponent::CK_UnusedFunctionPointer) 1264 continue; 1265 1266 // Get the final overrider for this method. 1267 FinalOverriders::OverriderInfo Overrider = 1268 Overriders.getOverrider(MD, MethodInfo.BaseOffset); 1269 1270 // Check if we need an adjustment at all. 1271 if (MethodInfo.BaseOffsetInLayoutClass == Overrider.Offset) { 1272 // When a return thunk is needed by a derived class that overrides a 1273 // virtual base, gcc uses a virtual 'this' adjustment as well. 1274 // While the thunk itself might be needed by vtables in subclasses or 1275 // in construction vtables, there doesn't seem to be a reason for using 1276 // the thunk in this vtable. Still, we do so to match gcc. 1277 if (VTableThunks.lookup(VTableIndex).Return.isEmpty()) 1278 continue; 1279 } 1280 1281 ThisAdjustment ThisAdjustment = 1282 ComputeThisAdjustment(MD, MethodInfo.BaseOffsetInLayoutClass, Overrider); 1283 1284 if (ThisAdjustment.isEmpty()) 1285 continue; 1286 1287 // Add it. 1288 VTableThunks[VTableIndex].This = ThisAdjustment; 1289 1290 if (isa<CXXDestructorDecl>(MD)) { 1291 // Add an adjustment for the deleting destructor as well. 1292 VTableThunks[VTableIndex + 1].This = ThisAdjustment; 1293 } 1294 } 1295 1296 /// Clear the method info map. 1297 MethodInfoMap.clear(); 1298 1299 if (isBuildingConstructorVTable()) { 1300 // We don't need to store thunk information for construction vtables. 1301 return; 1302 } 1303 1304 for (VTableThunksMapTy::const_iterator I = VTableThunks.begin(), 1305 E = VTableThunks.end(); I != E; ++I) { 1306 const VTableComponent &Component = Components[I->first]; 1307 const ThunkInfo &Thunk = I->second; 1308 const CXXMethodDecl *MD; 1309 1310 switch (Component.getKind()) { 1311 default: 1312 llvm_unreachable("Unexpected vtable component kind!"); 1313 case VTableComponent::CK_FunctionPointer: 1314 MD = Component.getFunctionDecl(); 1315 break; 1316 case VTableComponent::CK_CompleteDtorPointer: 1317 MD = Component.getDestructorDecl(); 1318 break; 1319 case VTableComponent::CK_DeletingDtorPointer: 1320 // We've already added the thunk when we saw the complete dtor pointer. 1321 continue; 1322 } 1323 1324 if (MD->getParent() == MostDerivedClass) 1325 AddThunk(MD, Thunk); 1326 } 1327} 1328 1329ReturnAdjustment VTableBuilder::ComputeReturnAdjustment(BaseOffset Offset) { 1330 ReturnAdjustment Adjustment; 1331 1332 if (!Offset.isEmpty()) { 1333 if (Offset.VirtualBase) { 1334 // Get the virtual base offset offset. 1335 if (Offset.DerivedClass == MostDerivedClass) { 1336 // We can get the offset offset directly from our map. 1337 Adjustment.VBaseOffsetOffset = 1338 VBaseOffsetOffsets.lookup(Offset.VirtualBase); 1339 } else { 1340 Adjustment.VBaseOffsetOffset = 1341 VTables.getVirtualBaseOffsetOffset(Offset.DerivedClass, 1342 Offset.VirtualBase); 1343 } 1344 } 1345 1346 Adjustment.NonVirtual = Offset.NonVirtualOffset; 1347 } 1348 1349 return Adjustment; 1350} 1351 1352BaseOffset 1353VTableBuilder::ComputeThisAdjustmentBaseOffset(BaseSubobject Base, 1354 BaseSubobject Derived) const { 1355 const CXXRecordDecl *BaseRD = Base.getBase(); 1356 const CXXRecordDecl *DerivedRD = Derived.getBase(); 1357 1358 CXXBasePaths Paths(/*FindAmbiguities=*/true, 1359 /*RecordPaths=*/true, /*DetectVirtual=*/true); 1360 1361 if (!const_cast<CXXRecordDecl *>(DerivedRD)-> 1362 isDerivedFrom(const_cast<CXXRecordDecl *>(BaseRD), Paths)) { 1363 assert(false && "Class must be derived from the passed in base class!"); 1364 return BaseOffset(); 1365 } 1366 1367 // We have to go through all the paths, and see which one leads us to the 1368 // right base subobject. 1369 for (CXXBasePaths::const_paths_iterator I = Paths.begin(), E = Paths.end(); 1370 I != E; ++I) { 1371 BaseOffset Offset = ComputeBaseOffset(Context, DerivedRD, *I); 1372 1373 CharUnits OffsetToBaseSubobject = 1374 CharUnits::fromQuantity(Offset.NonVirtualOffset); 1375 1376 if (Offset.VirtualBase) { 1377 // If we have a virtual base class, the non-virtual offset is relative 1378 // to the virtual base class offset. 1379 const ASTRecordLayout &LayoutClassLayout = 1380 Context.getASTRecordLayout(LayoutClass); 1381 1382 /// Get the virtual base offset, relative to the most derived class 1383 /// layout. 1384 OffsetToBaseSubobject += 1385 LayoutClassLayout.getVBaseClassOffset(Offset.VirtualBase); 1386 } else { 1387 // Otherwise, the non-virtual offset is relative to the derived class 1388 // offset. 1389 OffsetToBaseSubobject += Derived.getBaseOffset(); 1390 } 1391 1392 // Check if this path gives us the right base subobject. 1393 if (OffsetToBaseSubobject == Base.getBaseOffset()) { 1394 // Since we're going from the base class _to_ the derived class, we'll 1395 // invert the non-virtual offset here. 1396 Offset.NonVirtualOffset = -Offset.NonVirtualOffset; 1397 return Offset; 1398 } 1399 } 1400 1401 return BaseOffset(); 1402} 1403 1404ThisAdjustment 1405VTableBuilder::ComputeThisAdjustment(const CXXMethodDecl *MD, 1406 CharUnits BaseOffsetInLayoutClass, 1407 FinalOverriders::OverriderInfo Overrider) { 1408 // Ignore adjustments for pure virtual member functions. 1409 if (Overrider.Method->isPure()) 1410 return ThisAdjustment(); 1411 1412 BaseSubobject OverriddenBaseSubobject(MD->getParent(), 1413 BaseOffsetInLayoutClass); 1414 1415 BaseSubobject OverriderBaseSubobject(Overrider.Method->getParent(), 1416 Overrider.Offset); 1417 1418 // Compute the adjustment offset. 1419 BaseOffset Offset = ComputeThisAdjustmentBaseOffset(OverriddenBaseSubobject, 1420 OverriderBaseSubobject); 1421 if (Offset.isEmpty()) 1422 return ThisAdjustment(); 1423 1424 ThisAdjustment Adjustment; 1425 1426 if (Offset.VirtualBase) { 1427 // Get the vcall offset map for this virtual base. 1428 VCallOffsetMap &VCallOffsets = VCallOffsetsForVBases[Offset.VirtualBase]; 1429 1430 if (VCallOffsets.empty()) { 1431 // We don't have vcall offsets for this virtual base, go ahead and 1432 // build them. 1433 VCallAndVBaseOffsetBuilder Builder(MostDerivedClass, MostDerivedClass, 1434 /*FinalOverriders=*/0, 1435 BaseSubobject(Offset.VirtualBase, 1436 CharUnits::Zero()), 1437 /*BaseIsVirtual=*/true, 1438 /*OffsetInLayoutClass=*/0); 1439 1440 VCallOffsets = Builder.getVCallOffsets(); 1441 } 1442 1443 Adjustment.VCallOffsetOffset = VCallOffsets.getVCallOffsetOffset(MD); 1444 } 1445 1446 // Set the non-virtual part of the adjustment. 1447 Adjustment.NonVirtual = Offset.NonVirtualOffset; 1448 1449 return Adjustment; 1450} 1451 1452void 1453VTableBuilder::AddMethod(const CXXMethodDecl *MD, 1454 ReturnAdjustment ReturnAdjustment) { 1455 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) { 1456 assert(ReturnAdjustment.isEmpty() && 1457 "Destructor can't have return adjustment!"); 1458 1459 // Add both the complete destructor and the deleting destructor. 1460 Components.push_back(VTableComponent::MakeCompleteDtor(DD)); 1461 Components.push_back(VTableComponent::MakeDeletingDtor(DD)); 1462 } else { 1463 // Add the return adjustment if necessary. 1464 if (!ReturnAdjustment.isEmpty()) 1465 VTableThunks[Components.size()].Return = ReturnAdjustment; 1466 1467 // Add the function. 1468 Components.push_back(VTableComponent::MakeFunction(MD)); 1469 } 1470} 1471 1472/// OverridesIndirectMethodInBase - Return whether the given member function 1473/// overrides any methods in the set of given bases. 1474/// Unlike OverridesMethodInBase, this checks "overriders of overriders". 1475/// For example, if we have: 1476/// 1477/// struct A { virtual void f(); } 1478/// struct B : A { virtual void f(); } 1479/// struct C : B { virtual void f(); } 1480/// 1481/// OverridesIndirectMethodInBase will return true if given C::f as the method 1482/// and { A } as the set of bases. 1483static bool 1484OverridesIndirectMethodInBases(const CXXMethodDecl *MD, 1485 VTableBuilder::PrimaryBasesSetVectorTy &Bases) { 1486 if (Bases.count(MD->getParent())) 1487 return true; 1488 1489 for (CXXMethodDecl::method_iterator I = MD->begin_overridden_methods(), 1490 E = MD->end_overridden_methods(); I != E; ++I) { 1491 const CXXMethodDecl *OverriddenMD = *I; 1492 1493 // Check "indirect overriders". 1494 if (OverridesIndirectMethodInBases(OverriddenMD, Bases)) 1495 return true; 1496 } 1497 1498 return false; 1499} 1500 1501bool 1502VTableBuilder::IsOverriderUsed(const CXXMethodDecl *Overrider, 1503 uint64_t BaseOffsetInLayoutClass, 1504 const CXXRecordDecl *FirstBaseInPrimaryBaseChain, 1505 uint64_t FirstBaseOffsetInLayoutClass) const { 1506 // If the base and the first base in the primary base chain have the same 1507 // offsets, then this overrider will be used. 1508 if (BaseOffsetInLayoutClass == FirstBaseOffsetInLayoutClass) 1509 return true; 1510 1511 // We know now that Base (or a direct or indirect base of it) is a primary 1512 // base in part of the class hierarchy, but not a primary base in the most 1513 // derived class. 1514 1515 // If the overrider is the first base in the primary base chain, we know 1516 // that the overrider will be used. 1517 if (Overrider->getParent() == FirstBaseInPrimaryBaseChain) 1518 return true; 1519 1520 VTableBuilder::PrimaryBasesSetVectorTy PrimaryBases; 1521 1522 const CXXRecordDecl *RD = FirstBaseInPrimaryBaseChain; 1523 PrimaryBases.insert(RD); 1524 1525 // Now traverse the base chain, starting with the first base, until we find 1526 // the base that is no longer a primary base. 1527 while (true) { 1528 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); 1529 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase(); 1530 1531 if (!PrimaryBase) 1532 break; 1533 1534 if (Layout.isPrimaryBaseVirtual()) { 1535 assert(Layout.getVBaseClassOffsetInBits(PrimaryBase) == 0 && 1536 "Primary base should always be at offset 0!"); 1537 1538 const ASTRecordLayout &LayoutClassLayout = 1539 Context.getASTRecordLayout(LayoutClass); 1540 1541 // Now check if this is the primary base that is not a primary base in the 1542 // most derived class. 1543 if (LayoutClassLayout.getVBaseClassOffsetInBits(PrimaryBase) != 1544 FirstBaseOffsetInLayoutClass) { 1545 // We found it, stop walking the chain. 1546 break; 1547 } 1548 } else { 1549 assert(Layout.getBaseClassOffsetInBits(PrimaryBase) == 0 && 1550 "Primary base should always be at offset 0!"); 1551 } 1552 1553 if (!PrimaryBases.insert(PrimaryBase)) 1554 assert(false && "Found a duplicate primary base!"); 1555 1556 RD = PrimaryBase; 1557 } 1558 1559 // If the final overrider is an override of one of the primary bases, 1560 // then we know that it will be used. 1561 return OverridesIndirectMethodInBases(Overrider, PrimaryBases); 1562} 1563 1564/// FindNearestOverriddenMethod - Given a method, returns the overridden method 1565/// from the nearest base. Returns null if no method was found. 1566static const CXXMethodDecl * 1567FindNearestOverriddenMethod(const CXXMethodDecl *MD, 1568 VTableBuilder::PrimaryBasesSetVectorTy &Bases) { 1569 OverriddenMethodsSetTy OverriddenMethods; 1570 ComputeAllOverriddenMethods(MD, OverriddenMethods); 1571 1572 for (int I = Bases.size(), E = 0; I != E; --I) { 1573 const CXXRecordDecl *PrimaryBase = Bases[I - 1]; 1574 1575 // Now check the overriden methods. 1576 for (OverriddenMethodsSetTy::const_iterator I = OverriddenMethods.begin(), 1577 E = OverriddenMethods.end(); I != E; ++I) { 1578 const CXXMethodDecl *OverriddenMD = *I; 1579 1580 // We found our overridden method. 1581 if (OverriddenMD->getParent() == PrimaryBase) 1582 return OverriddenMD; 1583 } 1584 } 1585 1586 return 0; 1587} 1588 1589void 1590VTableBuilder::AddMethods(BaseSubobject Base, CharUnits BaseOffsetInLayoutClass, 1591 const CXXRecordDecl *FirstBaseInPrimaryBaseChain, 1592 CharUnits FirstBaseOffsetInLayoutClass, 1593 PrimaryBasesSetVectorTy &PrimaryBases) { 1594 const CXXRecordDecl *RD = Base.getBase(); 1595 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); 1596 1597 if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) { 1598 CharUnits PrimaryBaseOffset; 1599 CharUnits PrimaryBaseOffsetInLayoutClass; 1600 if (Layout.isPrimaryBaseVirtual()) { 1601 assert(Layout.getVBaseClassOffsetInBits(PrimaryBase) == 0 && 1602 "Primary vbase should have a zero offset!"); 1603 1604 const ASTRecordLayout &MostDerivedClassLayout = 1605 Context.getASTRecordLayout(MostDerivedClass); 1606 1607 PrimaryBaseOffset = 1608 MostDerivedClassLayout.getVBaseClassOffset(PrimaryBase); 1609 1610 const ASTRecordLayout &LayoutClassLayout = 1611 Context.getASTRecordLayout(LayoutClass); 1612 1613 PrimaryBaseOffsetInLayoutClass = 1614 LayoutClassLayout.getVBaseClassOffset(PrimaryBase); 1615 } else { 1616 assert(Layout.getBaseClassOffsetInBits(PrimaryBase) == 0 && 1617 "Primary base should have a zero offset!"); 1618 1619 PrimaryBaseOffset = Base.getBaseOffset(); 1620 PrimaryBaseOffsetInLayoutClass = BaseOffsetInLayoutClass; 1621 } 1622 1623 AddMethods(BaseSubobject(PrimaryBase, PrimaryBaseOffset), 1624 PrimaryBaseOffsetInLayoutClass, FirstBaseInPrimaryBaseChain, 1625 FirstBaseOffsetInLayoutClass, PrimaryBases); 1626 1627 if (!PrimaryBases.insert(PrimaryBase)) 1628 assert(false && "Found a duplicate primary base!"); 1629 } 1630 1631 // Now go through all virtual member functions and add them. 1632 for (CXXRecordDecl::method_iterator I = RD->method_begin(), 1633 E = RD->method_end(); I != E; ++I) { 1634 const CXXMethodDecl *MD = *I; 1635 1636 if (!MD->isVirtual()) 1637 continue; 1638 1639 // Get the final overrider. 1640 FinalOverriders::OverriderInfo Overrider = 1641 Overriders.getOverrider(MD, Base.getBaseOffset()); 1642 1643 // Check if this virtual member function overrides a method in a primary 1644 // base. If this is the case, and the return type doesn't require adjustment 1645 // then we can just use the member function from the primary base. 1646 if (const CXXMethodDecl *OverriddenMD = 1647 FindNearestOverriddenMethod(MD, PrimaryBases)) { 1648 if (ComputeReturnAdjustmentBaseOffset(Context, MD, 1649 OverriddenMD).isEmpty()) { 1650 // Replace the method info of the overridden method with our own 1651 // method. 1652 assert(MethodInfoMap.count(OverriddenMD) && 1653 "Did not find the overridden method!"); 1654 MethodInfo &OverriddenMethodInfo = MethodInfoMap[OverriddenMD]; 1655 1656 MethodInfo MethodInfo(Base.getBaseOffset(), 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(), BaseOffsetInLayoutClass, 1698 Components.size()); 1699 1700 assert(!MethodInfoMap.count(MD) && 1701 "Should not have method info for this method yet!"); 1702 MethodInfoMap.insert(std::make_pair(MD, MethodInfo)); 1703 1704 // Check if this overrider is going to be used. 1705 const CXXMethodDecl *OverriderMD = Overrider.Method; 1706 if (!IsOverriderUsed(OverriderMD, Context.toBits(BaseOffsetInLayoutClass), 1707 FirstBaseInPrimaryBaseChain, 1708 Context.toBits(FirstBaseOffsetInLayoutClass))) { 1709 Components.push_back(VTableComponent::MakeUnusedFunction(OverriderMD)); 1710 continue; 1711 } 1712 1713 // Check if this overrider needs a return adjustment. 1714 // We don't want to do this for pure virtual member functions. 1715 BaseOffset ReturnAdjustmentOffset; 1716 if (!OverriderMD->isPure()) { 1717 ReturnAdjustmentOffset = 1718 ComputeReturnAdjustmentBaseOffset(Context, OverriderMD, MD); 1719 } 1720 1721 ReturnAdjustment ReturnAdjustment = 1722 ComputeReturnAdjustment(ReturnAdjustmentOffset); 1723 1724 AddMethod(Overrider.Method, ReturnAdjustment); 1725 } 1726} 1727 1728void VTableBuilder::LayoutVTable() { 1729 LayoutPrimaryAndSecondaryVTables(BaseSubobject(MostDerivedClass, 1730 CharUnits::Zero()), 1731 /*BaseIsMorallyVirtual=*/false, 1732 MostDerivedClassIsVirtual, 1733 MostDerivedClassOffset); 1734 1735 VisitedVirtualBasesSetTy VBases; 1736 1737 // Determine the primary virtual bases. 1738 DeterminePrimaryVirtualBases(MostDerivedClass, MostDerivedClassOffset, 1739 VBases); 1740 VBases.clear(); 1741 1742 LayoutVTablesForVirtualBases(MostDerivedClass, VBases); 1743} 1744 1745void 1746VTableBuilder::LayoutPrimaryAndSecondaryVTables(BaseSubobject Base, 1747 bool BaseIsMorallyVirtual, 1748 bool BaseIsVirtualInLayoutClass, 1749 uint64_t OffsetInLayoutClass) { 1750 assert(Base.getBase()->isDynamicClass() && "class does not have a vtable!"); 1751 1752 // Add vcall and vbase offsets for this vtable. 1753 VCallAndVBaseOffsetBuilder Builder(MostDerivedClass, LayoutClass, &Overriders, 1754 Base, BaseIsVirtualInLayoutClass, 1755 OffsetInLayoutClass); 1756 Components.append(Builder.components_begin(), Builder.components_end()); 1757 1758 // Check if we need to add these vcall offsets. 1759 if (BaseIsVirtualInLayoutClass && !Builder.getVCallOffsets().empty()) { 1760 VCallOffsetMap &VCallOffsets = VCallOffsetsForVBases[Base.getBase()]; 1761 1762 if (VCallOffsets.empty()) 1763 VCallOffsets = Builder.getVCallOffsets(); 1764 } 1765 1766 // If we're laying out the most derived class we want to keep track of the 1767 // virtual base class offset offsets. 1768 if (Base.getBase() == MostDerivedClass) 1769 VBaseOffsetOffsets = Builder.getVBaseOffsetOffsets(); 1770 1771 // Add the offset to top. 1772 // FIXME: We should not use / 8 here. 1773 int64_t OffsetToTop = -(int64_t)(OffsetInLayoutClass - 1774 MostDerivedClassOffset) / 8; 1775 Components.push_back(VTableComponent::MakeOffsetToTop(OffsetToTop)); 1776 1777 // Next, add the RTTI. 1778 Components.push_back(VTableComponent::MakeRTTI(MostDerivedClass)); 1779 1780 uint64_t AddressPoint = Components.size(); 1781 1782 // Now go through all virtual member functions and add them. 1783 PrimaryBasesSetVectorTy PrimaryBases; 1784 AddMethods(Base, Context.toCharUnitsFromBits(OffsetInLayoutClass), 1785 Base.getBase(), Context.toCharUnitsFromBits(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 Out << " -- (" << Base.getBase()->getQualifiedNameAsString(); 2137 Out << ", " << Base.getBaseOffset().getQuantity(); 2138 Out << ") vtable address --\n"; 2139 } else { 2140 CharUnits BaseOffset = 2141 AddressPointsByIndex.lower_bound(NextIndex)->second.getBaseOffset(); 2142 2143 // We store the class names in a set to get a stable order. 2144 std::set<std::string> ClassNames; 2145 for (std::multimap<uint64_t, BaseSubobject>::const_iterator I = 2146 AddressPointsByIndex.lower_bound(NextIndex), E = 2147 AddressPointsByIndex.upper_bound(NextIndex); I != E; ++I) { 2148 assert(I->second.getBaseOffset() == BaseOffset && 2149 "Invalid base offset!"); 2150 const CXXRecordDecl *RD = I->second.getBase(); 2151 ClassNames.insert(RD->getQualifiedNameAsString()); 2152 } 2153 2154 for (std::set<std::string>::const_iterator I = ClassNames.begin(), 2155 E = ClassNames.end(); I != E; ++I) { 2156 Out << " -- (" << *I; 2157 Out << ", " << BaseOffset.getQuantity() << ") vtable address --\n"; 2158 } 2159 } 2160 } 2161 } 2162 2163 Out << '\n'; 2164 2165 if (isBuildingConstructorVTable()) 2166 return; 2167 2168 if (MostDerivedClass->getNumVBases()) { 2169 // We store the virtual base class names and their offsets in a map to get 2170 // a stable order. 2171 2172 std::map<std::string, int64_t> ClassNamesAndOffsets; 2173 for (VBaseOffsetOffsetsMapTy::const_iterator I = VBaseOffsetOffsets.begin(), 2174 E = VBaseOffsetOffsets.end(); I != E; ++I) { 2175 std::string ClassName = I->first->getQualifiedNameAsString(); 2176 int64_t OffsetOffset = I->second; 2177 ClassNamesAndOffsets.insert(std::make_pair(ClassName, OffsetOffset)); 2178 } 2179 2180 Out << "Virtual base offset offsets for '"; 2181 Out << MostDerivedClass->getQualifiedNameAsString() << "' ("; 2182 Out << ClassNamesAndOffsets.size(); 2183 Out << (ClassNamesAndOffsets.size() == 1 ? " entry" : " entries") << ").\n"; 2184 2185 for (std::map<std::string, int64_t>::const_iterator I = 2186 ClassNamesAndOffsets.begin(), E = ClassNamesAndOffsets.end(); 2187 I != E; ++I) 2188 Out << " " << I->first << " | " << I->second << '\n'; 2189 2190 Out << "\n"; 2191 } 2192 2193 if (!Thunks.empty()) { 2194 // We store the method names in a map to get a stable order. 2195 std::map<std::string, const CXXMethodDecl *> MethodNamesAndDecls; 2196 2197 for (ThunksMapTy::const_iterator I = Thunks.begin(), E = Thunks.end(); 2198 I != E; ++I) { 2199 const CXXMethodDecl *MD = I->first; 2200 std::string MethodName = 2201 PredefinedExpr::ComputeName(PredefinedExpr::PrettyFunctionNoVirtual, 2202 MD); 2203 2204 MethodNamesAndDecls.insert(std::make_pair(MethodName, MD)); 2205 } 2206 2207 for (std::map<std::string, const CXXMethodDecl *>::const_iterator I = 2208 MethodNamesAndDecls.begin(), E = MethodNamesAndDecls.end(); 2209 I != E; ++I) { 2210 const std::string &MethodName = I->first; 2211 const CXXMethodDecl *MD = I->second; 2212 2213 ThunkInfoVectorTy ThunksVector = Thunks[MD]; 2214 std::sort(ThunksVector.begin(), ThunksVector.end()); 2215 2216 Out << "Thunks for '" << MethodName << "' (" << ThunksVector.size(); 2217 Out << (ThunksVector.size() == 1 ? " entry" : " entries") << ").\n"; 2218 2219 for (unsigned I = 0, E = ThunksVector.size(); I != E; ++I) { 2220 const ThunkInfo &Thunk = ThunksVector[I]; 2221 2222 Out << llvm::format("%4d | ", I); 2223 2224 // If this function pointer has a return pointer adjustment, dump it. 2225 if (!Thunk.Return.isEmpty()) { 2226 Out << "return adjustment: " << Thunk.This.NonVirtual; 2227 Out << " non-virtual"; 2228 if (Thunk.Return.VBaseOffsetOffset) { 2229 Out << ", " << Thunk.Return.VBaseOffsetOffset; 2230 Out << " vbase offset offset"; 2231 } 2232 2233 if (!Thunk.This.isEmpty()) 2234 Out << "\n "; 2235 } 2236 2237 // If this function pointer has a 'this' pointer adjustment, dump it. 2238 if (!Thunk.This.isEmpty()) { 2239 Out << "this adjustment: "; 2240 Out << Thunk.This.NonVirtual << " non-virtual"; 2241 2242 if (Thunk.This.VCallOffsetOffset) { 2243 Out << ", " << Thunk.This.VCallOffsetOffset; 2244 Out << " vcall offset offset"; 2245 } 2246 } 2247 2248 Out << '\n'; 2249 } 2250 2251 Out << '\n'; 2252 2253 } 2254 } 2255} 2256 2257} 2258 2259static void 2260CollectPrimaryBases(const CXXRecordDecl *RD, ASTContext &Context, 2261 VTableBuilder::PrimaryBasesSetVectorTy &PrimaryBases) { 2262 while (RD) { 2263 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); 2264 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase(); 2265 if (PrimaryBase) 2266 PrimaryBases.insert(PrimaryBase); 2267 2268 RD = PrimaryBase; 2269 } 2270} 2271 2272void CodeGenVTables::ComputeMethodVTableIndices(const CXXRecordDecl *RD) { 2273 2274 // Itanium C++ ABI 2.5.2: 2275 // The order of the virtual function pointers in a virtual table is the 2276 // order of declaration of the corresponding member functions in the class. 2277 // 2278 // There is an entry for any virtual function declared in a class, 2279 // whether it is a new function or overrides a base class function, 2280 // unless it overrides a function from the primary base, and conversion 2281 // between their return types does not require an adjustment. 2282 2283 int64_t CurrentIndex = 0; 2284 2285 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD); 2286 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase(); 2287 2288 if (PrimaryBase) { 2289 assert(PrimaryBase->isDefinition() && 2290 "Should have the definition decl of the primary base!"); 2291 2292 // Since the record decl shares its vtable pointer with the primary base 2293 // we need to start counting at the end of the primary base's vtable. 2294 CurrentIndex = getNumVirtualFunctionPointers(PrimaryBase); 2295 } 2296 2297 // Collect all the primary bases, so we can check whether methods override 2298 // a method from the base. 2299 VTableBuilder::PrimaryBasesSetVectorTy PrimaryBases; 2300 CollectPrimaryBases(RD, CGM.getContext(), PrimaryBases); 2301 2302 const CXXDestructorDecl *ImplicitVirtualDtor = 0; 2303 2304 for (CXXRecordDecl::method_iterator i = RD->method_begin(), 2305 e = RD->method_end(); i != e; ++i) { 2306 const CXXMethodDecl *MD = *i; 2307 2308 // We only want virtual methods. 2309 if (!MD->isVirtual()) 2310 continue; 2311 2312 // Check if this method overrides a method in the primary base. 2313 if (const CXXMethodDecl *OverriddenMD = 2314 FindNearestOverriddenMethod(MD, PrimaryBases)) { 2315 // Check if converting from the return type of the method to the 2316 // return type of the overridden method requires conversion. 2317 if (ComputeReturnAdjustmentBaseOffset(CGM.getContext(), MD, 2318 OverriddenMD).isEmpty()) { 2319 // This index is shared between the index in the vtable of the primary 2320 // base class. 2321 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) { 2322 const CXXDestructorDecl *OverriddenDD = 2323 cast<CXXDestructorDecl>(OverriddenMD); 2324 2325 // Add both the complete and deleting entries. 2326 MethodVTableIndices[GlobalDecl(DD, Dtor_Complete)] = 2327 getMethodVTableIndex(GlobalDecl(OverriddenDD, Dtor_Complete)); 2328 MethodVTableIndices[GlobalDecl(DD, Dtor_Deleting)] = 2329 getMethodVTableIndex(GlobalDecl(OverriddenDD, Dtor_Deleting)); 2330 } else { 2331 MethodVTableIndices[MD] = getMethodVTableIndex(OverriddenMD); 2332 } 2333 2334 // We don't need to add an entry for this method. 2335 continue; 2336 } 2337 } 2338 2339 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) { 2340 if (MD->isImplicit()) { 2341 assert(!ImplicitVirtualDtor && 2342 "Did already see an implicit virtual dtor!"); 2343 ImplicitVirtualDtor = DD; 2344 continue; 2345 } 2346 2347 // Add the complete dtor. 2348 MethodVTableIndices[GlobalDecl(DD, Dtor_Complete)] = CurrentIndex++; 2349 2350 // Add the deleting dtor. 2351 MethodVTableIndices[GlobalDecl(DD, Dtor_Deleting)] = CurrentIndex++; 2352 } else { 2353 // Add the entry. 2354 MethodVTableIndices[MD] = CurrentIndex++; 2355 } 2356 } 2357 2358 if (ImplicitVirtualDtor) { 2359 // Itanium C++ ABI 2.5.2: 2360 // If a class has an implicitly-defined virtual destructor, 2361 // its entries come after the declared virtual function pointers. 2362 2363 // Add the complete dtor. 2364 MethodVTableIndices[GlobalDecl(ImplicitVirtualDtor, Dtor_Complete)] = 2365 CurrentIndex++; 2366 2367 // Add the deleting dtor. 2368 MethodVTableIndices[GlobalDecl(ImplicitVirtualDtor, Dtor_Deleting)] = 2369 CurrentIndex++; 2370 } 2371 2372 NumVirtualFunctionPointers[RD] = CurrentIndex; 2373} 2374 2375bool CodeGenVTables::ShouldEmitVTableInThisTU(const CXXRecordDecl *RD) { 2376 assert(RD->isDynamicClass() && "Non dynamic classes have no VTable."); 2377 2378 TemplateSpecializationKind TSK = RD->getTemplateSpecializationKind(); 2379 if (TSK == TSK_ExplicitInstantiationDeclaration) 2380 return false; 2381 2382 const CXXMethodDecl *KeyFunction = CGM.getContext().getKeyFunction(RD); 2383 if (!KeyFunction) 2384 return true; 2385 2386 // Itanium C++ ABI, 5.2.6 Instantiated Templates: 2387 // An instantiation of a class template requires: 2388 // - In the object where instantiated, the virtual table... 2389 if (TSK == TSK_ImplicitInstantiation || 2390 TSK == TSK_ExplicitInstantiationDefinition) 2391 return true; 2392 2393 // If we're building with optimization, we always emit VTables since that 2394 // allows for virtual function calls to be devirtualized. 2395 // (We don't want to do this in -fapple-kext mode however). 2396 if (CGM.getCodeGenOpts().OptimizationLevel && !CGM.getLangOptions().AppleKext) 2397 return true; 2398 2399 return KeyFunction->hasBody(); 2400} 2401 2402uint64_t CodeGenVTables::getNumVirtualFunctionPointers(const CXXRecordDecl *RD) { 2403 llvm::DenseMap<const CXXRecordDecl *, uint64_t>::iterator I = 2404 NumVirtualFunctionPointers.find(RD); 2405 if (I != NumVirtualFunctionPointers.end()) 2406 return I->second; 2407 2408 ComputeMethodVTableIndices(RD); 2409 2410 I = NumVirtualFunctionPointers.find(RD); 2411 assert(I != NumVirtualFunctionPointers.end() && "Did not find entry!"); 2412 return I->second; 2413} 2414 2415uint64_t CodeGenVTables::getMethodVTableIndex(GlobalDecl GD) { 2416 MethodVTableIndicesTy::iterator I = MethodVTableIndices.find(GD); 2417 if (I != MethodVTableIndices.end()) 2418 return I->second; 2419 2420 const CXXRecordDecl *RD = cast<CXXMethodDecl>(GD.getDecl())->getParent(); 2421 2422 ComputeMethodVTableIndices(RD); 2423 2424 I = MethodVTableIndices.find(GD); 2425 assert(I != MethodVTableIndices.end() && "Did not find index!"); 2426 return I->second; 2427} 2428 2429int64_t CodeGenVTables::getVirtualBaseOffsetOffset(const CXXRecordDecl *RD, 2430 const CXXRecordDecl *VBase) { 2431 ClassPairTy ClassPair(RD, VBase); 2432 2433 VirtualBaseClassOffsetOffsetsMapTy::iterator I = 2434 VirtualBaseClassOffsetOffsets.find(ClassPair); 2435 if (I != VirtualBaseClassOffsetOffsets.end()) 2436 return I->second; 2437 2438 VCallAndVBaseOffsetBuilder Builder(RD, RD, /*FinalOverriders=*/0, 2439 BaseSubobject(RD, CharUnits::Zero()), 2440 /*BaseIsVirtual=*/false, 2441 /*OffsetInLayoutClass=*/0); 2442 2443 for (VCallAndVBaseOffsetBuilder::VBaseOffsetOffsetsMapTy::const_iterator I = 2444 Builder.getVBaseOffsetOffsets().begin(), 2445 E = Builder.getVBaseOffsetOffsets().end(); I != E; ++I) { 2446 // Insert all types. 2447 ClassPairTy ClassPair(RD, I->first); 2448 2449 VirtualBaseClassOffsetOffsets.insert(std::make_pair(ClassPair, I->second)); 2450 } 2451 2452 I = VirtualBaseClassOffsetOffsets.find(ClassPair); 2453 assert(I != VirtualBaseClassOffsetOffsets.end() && "Did not find index!"); 2454 2455 return I->second; 2456} 2457 2458uint64_t 2459CodeGenVTables::getAddressPoint(BaseSubobject Base, const CXXRecordDecl *RD) { 2460 assert(AddressPoints.count(std::make_pair(RD, Base)) && 2461 "Did not find address point!"); 2462 2463 uint64_t AddressPoint = AddressPoints.lookup(std::make_pair(RD, Base)); 2464 assert(AddressPoint && "Address point must not be zero!"); 2465 2466 return AddressPoint; 2467} 2468 2469llvm::Constant *CodeGenModule::GetAddrOfThunk(GlobalDecl GD, 2470 const ThunkInfo &Thunk) { 2471 const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); 2472 2473 // Compute the mangled name. 2474 llvm::SmallString<256> Name; 2475 llvm::raw_svector_ostream Out(Name); 2476 if (const CXXDestructorDecl* DD = dyn_cast<CXXDestructorDecl>(MD)) 2477 getCXXABI().getMangleContext().mangleCXXDtorThunk(DD, GD.getDtorType(), 2478 Thunk.This, Out); 2479 else 2480 getCXXABI().getMangleContext().mangleThunk(MD, Thunk, Out); 2481 Out.flush(); 2482 2483 const llvm::Type *Ty = getTypes().GetFunctionTypeForVTable(GD); 2484 return GetOrCreateLLVMFunction(Name, Ty, GD, /*ForVTable=*/true); 2485} 2486 2487static llvm::Value *PerformTypeAdjustment(CodeGenFunction &CGF, 2488 llvm::Value *Ptr, 2489 int64_t NonVirtualAdjustment, 2490 int64_t VirtualAdjustment) { 2491 if (!NonVirtualAdjustment && !VirtualAdjustment) 2492 return Ptr; 2493 2494 const llvm::Type *Int8PtrTy = 2495 llvm::Type::getInt8PtrTy(CGF.getLLVMContext()); 2496 2497 llvm::Value *V = CGF.Builder.CreateBitCast(Ptr, Int8PtrTy); 2498 2499 if (NonVirtualAdjustment) { 2500 // Do the non-virtual adjustment. 2501 V = CGF.Builder.CreateConstInBoundsGEP1_64(V, NonVirtualAdjustment); 2502 } 2503 2504 if (VirtualAdjustment) { 2505 const llvm::Type *PtrDiffTy = 2506 CGF.ConvertType(CGF.getContext().getPointerDiffType()); 2507 2508 // Do the virtual adjustment. 2509 llvm::Value *VTablePtrPtr = 2510 CGF.Builder.CreateBitCast(V, Int8PtrTy->getPointerTo()); 2511 2512 llvm::Value *VTablePtr = CGF.Builder.CreateLoad(VTablePtrPtr); 2513 2514 llvm::Value *OffsetPtr = 2515 CGF.Builder.CreateConstInBoundsGEP1_64(VTablePtr, VirtualAdjustment); 2516 2517 OffsetPtr = CGF.Builder.CreateBitCast(OffsetPtr, PtrDiffTy->getPointerTo()); 2518 2519 // Load the adjustment offset from the vtable. 2520 llvm::Value *Offset = CGF.Builder.CreateLoad(OffsetPtr); 2521 2522 // Adjust our pointer. 2523 V = CGF.Builder.CreateInBoundsGEP(V, Offset); 2524 } 2525 2526 // Cast back to the original type. 2527 return CGF.Builder.CreateBitCast(V, Ptr->getType()); 2528} 2529 2530static void setThunkVisibility(CodeGenModule &CGM, const CXXMethodDecl *MD, 2531 const ThunkInfo &Thunk, llvm::Function *Fn) { 2532 CGM.setGlobalVisibility(Fn, MD); 2533 2534 if (!CGM.getCodeGenOpts().HiddenWeakVTables) 2535 return; 2536 2537 // If the thunk has weak/linkonce linkage, but the function must be 2538 // emitted in every translation unit that references it, then we can 2539 // emit its thunks with hidden visibility, since its thunks must be 2540 // emitted when the function is. 2541 2542 // This follows CodeGenModule::setTypeVisibility; see the comments 2543 // there for explanation. 2544 2545 if ((Fn->getLinkage() != llvm::GlobalVariable::LinkOnceODRLinkage && 2546 Fn->getLinkage() != llvm::GlobalVariable::WeakODRLinkage) || 2547 Fn->getVisibility() != llvm::GlobalVariable::DefaultVisibility) 2548 return; 2549 2550 if (MD->getExplicitVisibility()) 2551 return; 2552 2553 switch (MD->getTemplateSpecializationKind()) { 2554 case TSK_ExplicitInstantiationDefinition: 2555 case TSK_ExplicitInstantiationDeclaration: 2556 return; 2557 2558 case TSK_Undeclared: 2559 break; 2560 2561 case TSK_ExplicitSpecialization: 2562 case TSK_ImplicitInstantiation: 2563 if (!CGM.getCodeGenOpts().HiddenWeakTemplateVTables) 2564 return; 2565 break; 2566 } 2567 2568 // If there's an explicit definition, and that definition is 2569 // out-of-line, then we can't assume that all users will have a 2570 // definition to emit. 2571 const FunctionDecl *Def = 0; 2572 if (MD->hasBody(Def) && Def->isOutOfLine()) 2573 return; 2574 2575 Fn->setVisibility(llvm::GlobalValue::HiddenVisibility); 2576} 2577 2578#ifndef NDEBUG 2579static bool similar(const ABIArgInfo &infoL, CanQualType typeL, 2580 const ABIArgInfo &infoR, CanQualType typeR) { 2581 return (infoL.getKind() == infoR.getKind() && 2582 (typeL == typeR || 2583 (isa<PointerType>(typeL) && isa<PointerType>(typeR)) || 2584 (isa<ReferenceType>(typeL) && isa<ReferenceType>(typeR)))); 2585} 2586#endif 2587 2588void CodeGenFunction::GenerateThunk(llvm::Function *Fn, 2589 const CGFunctionInfo &FnInfo, 2590 GlobalDecl GD, const ThunkInfo &Thunk) { 2591 const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); 2592 const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>(); 2593 QualType ResultType = FPT->getResultType(); 2594 QualType ThisType = MD->getThisType(getContext()); 2595 2596 FunctionArgList FunctionArgs; 2597 2598 // FIXME: It would be nice if more of this code could be shared with 2599 // CodeGenFunction::GenerateCode. 2600 2601 // Create the implicit 'this' parameter declaration. 2602 CurGD = GD; 2603 CGM.getCXXABI().BuildInstanceFunctionParams(*this, ResultType, FunctionArgs); 2604 2605 // Add the rest of the parameters. 2606 for (FunctionDecl::param_const_iterator I = MD->param_begin(), 2607 E = MD->param_end(); I != E; ++I) { 2608 ParmVarDecl *Param = *I; 2609 2610 FunctionArgs.push_back(Param); 2611 } 2612 2613 StartFunction(GlobalDecl(), ResultType, Fn, FnInfo, FunctionArgs, 2614 SourceLocation()); 2615 2616 CGM.getCXXABI().EmitInstanceFunctionProlog(*this); 2617 2618 // Adjust the 'this' pointer if necessary. 2619 llvm::Value *AdjustedThisPtr = 2620 PerformTypeAdjustment(*this, LoadCXXThis(), 2621 Thunk.This.NonVirtual, 2622 Thunk.This.VCallOffsetOffset); 2623 2624 CallArgList CallArgs; 2625 2626 // Add our adjusted 'this' pointer. 2627 CallArgs.push_back(std::make_pair(RValue::get(AdjustedThisPtr), ThisType)); 2628 2629 // Add the rest of the parameters. 2630 for (FunctionDecl::param_const_iterator I = MD->param_begin(), 2631 E = MD->param_end(); I != E; ++I) { 2632 ParmVarDecl *param = *I; 2633 EmitDelegateCallArg(CallArgs, param); 2634 } 2635 2636 // Get our callee. 2637 const llvm::Type *Ty = 2638 CGM.getTypes().GetFunctionType(CGM.getTypes().getFunctionInfo(GD), 2639 FPT->isVariadic()); 2640 llvm::Value *Callee = CGM.GetAddrOfFunction(GD, Ty, /*ForVTable=*/true); 2641 2642#ifndef NDEBUG 2643 const CGFunctionInfo &CallFnInfo = 2644 CGM.getTypes().getFunctionInfo(ResultType, CallArgs, FPT->getExtInfo()); 2645 assert(CallFnInfo.getRegParm() == FnInfo.getRegParm() && 2646 CallFnInfo.isNoReturn() == FnInfo.isNoReturn() && 2647 CallFnInfo.getCallingConvention() == FnInfo.getCallingConvention()); 2648 assert(similar(CallFnInfo.getReturnInfo(), CallFnInfo.getReturnType(), 2649 FnInfo.getReturnInfo(), FnInfo.getReturnType())); 2650 assert(CallFnInfo.arg_size() == FnInfo.arg_size()); 2651 for (unsigned i = 0, e = FnInfo.arg_size(); i != e; ++i) 2652 assert(similar(CallFnInfo.arg_begin()[i].info, 2653 CallFnInfo.arg_begin()[i].type, 2654 FnInfo.arg_begin()[i].info, FnInfo.arg_begin()[i].type)); 2655#endif 2656 2657 // Determine whether we have a return value slot to use. 2658 ReturnValueSlot Slot; 2659 if (!ResultType->isVoidType() && 2660 FnInfo.getReturnInfo().getKind() == ABIArgInfo::Indirect && 2661 hasAggregateLLVMType(CurFnInfo->getReturnType())) 2662 Slot = ReturnValueSlot(ReturnValue, ResultType.isVolatileQualified()); 2663 2664 // Now emit our call. 2665 RValue RV = EmitCall(FnInfo, Callee, Slot, CallArgs, MD); 2666 2667 if (!Thunk.Return.isEmpty()) { 2668 // Emit the return adjustment. 2669 bool NullCheckValue = !ResultType->isReferenceType(); 2670 2671 llvm::BasicBlock *AdjustNull = 0; 2672 llvm::BasicBlock *AdjustNotNull = 0; 2673 llvm::BasicBlock *AdjustEnd = 0; 2674 2675 llvm::Value *ReturnValue = RV.getScalarVal(); 2676 2677 if (NullCheckValue) { 2678 AdjustNull = createBasicBlock("adjust.null"); 2679 AdjustNotNull = createBasicBlock("adjust.notnull"); 2680 AdjustEnd = createBasicBlock("adjust.end"); 2681 2682 llvm::Value *IsNull = Builder.CreateIsNull(ReturnValue); 2683 Builder.CreateCondBr(IsNull, AdjustNull, AdjustNotNull); 2684 EmitBlock(AdjustNotNull); 2685 } 2686 2687 ReturnValue = PerformTypeAdjustment(*this, ReturnValue, 2688 Thunk.Return.NonVirtual, 2689 Thunk.Return.VBaseOffsetOffset); 2690 2691 if (NullCheckValue) { 2692 Builder.CreateBr(AdjustEnd); 2693 EmitBlock(AdjustNull); 2694 Builder.CreateBr(AdjustEnd); 2695 EmitBlock(AdjustEnd); 2696 2697 llvm::PHINode *PHI = Builder.CreatePHI(ReturnValue->getType()); 2698 PHI->reserveOperandSpace(2); 2699 PHI->addIncoming(ReturnValue, AdjustNotNull); 2700 PHI->addIncoming(llvm::Constant::getNullValue(ReturnValue->getType()), 2701 AdjustNull); 2702 ReturnValue = PHI; 2703 } 2704 2705 RV = RValue::get(ReturnValue); 2706 } 2707 2708 if (!ResultType->isVoidType() && Slot.isNull()) 2709 CGM.getCXXABI().EmitReturnFromThunk(*this, RV, ResultType); 2710 2711 FinishFunction(); 2712 2713 // Set the right linkage. 2714 CGM.setFunctionLinkage(MD, Fn); 2715 2716 // Set the right visibility. 2717 setThunkVisibility(CGM, MD, Thunk, Fn); 2718} 2719 2720void CodeGenVTables::EmitThunk(GlobalDecl GD, const ThunkInfo &Thunk, 2721 bool UseAvailableExternallyLinkage) 2722{ 2723 const CGFunctionInfo &FnInfo = CGM.getTypes().getFunctionInfo(GD); 2724 2725 // FIXME: re-use FnInfo in this computation. 2726 llvm::Constant *Entry = CGM.GetAddrOfThunk(GD, Thunk); 2727 2728 // Strip off a bitcast if we got one back. 2729 if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(Entry)) { 2730 assert(CE->getOpcode() == llvm::Instruction::BitCast); 2731 Entry = CE->getOperand(0); 2732 } 2733 2734 // There's already a declaration with the same name, check if it has the same 2735 // type or if we need to replace it. 2736 if (cast<llvm::GlobalValue>(Entry)->getType()->getElementType() != 2737 CGM.getTypes().GetFunctionTypeForVTable(GD)) { 2738 llvm::GlobalValue *OldThunkFn = cast<llvm::GlobalValue>(Entry); 2739 2740 // If the types mismatch then we have to rewrite the definition. 2741 assert(OldThunkFn->isDeclaration() && 2742 "Shouldn't replace non-declaration"); 2743 2744 // Remove the name from the old thunk function and get a new thunk. 2745 OldThunkFn->setName(llvm::StringRef()); 2746 Entry = CGM.GetAddrOfThunk(GD, Thunk); 2747 2748 // If needed, replace the old thunk with a bitcast. 2749 if (!OldThunkFn->use_empty()) { 2750 llvm::Constant *NewPtrForOldDecl = 2751 llvm::ConstantExpr::getBitCast(Entry, OldThunkFn->getType()); 2752 OldThunkFn->replaceAllUsesWith(NewPtrForOldDecl); 2753 } 2754 2755 // Remove the old thunk. 2756 OldThunkFn->eraseFromParent(); 2757 } 2758 2759 llvm::Function *ThunkFn = cast<llvm::Function>(Entry); 2760 2761 if (!ThunkFn->isDeclaration()) { 2762 if (UseAvailableExternallyLinkage) { 2763 // There is already a thunk emitted for this function, do nothing. 2764 return; 2765 } 2766 2767 // If a function has a body, it should have available_externally linkage. 2768 assert(ThunkFn->hasAvailableExternallyLinkage() && 2769 "Function should have available_externally linkage!"); 2770 2771 // Change the linkage. 2772 CGM.setFunctionLinkage(cast<CXXMethodDecl>(GD.getDecl()), ThunkFn); 2773 return; 2774 } 2775 2776 // Actually generate the thunk body. 2777 CodeGenFunction(CGM).GenerateThunk(ThunkFn, FnInfo, GD, Thunk); 2778 2779 if (UseAvailableExternallyLinkage) 2780 ThunkFn->setLinkage(llvm::GlobalValue::AvailableExternallyLinkage); 2781} 2782 2783void CodeGenVTables::MaybeEmitThunkAvailableExternally(GlobalDecl GD, 2784 const ThunkInfo &Thunk) { 2785 // We only want to do this when building with optimizations. 2786 if (!CGM.getCodeGenOpts().OptimizationLevel) 2787 return; 2788 2789 // We can't emit thunks for member functions with incomplete types. 2790 const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); 2791 if (CGM.getTypes().VerifyFuncTypeComplete(MD->getType().getTypePtr())) 2792 return; 2793 2794 EmitThunk(GD, Thunk, /*UseAvailableExternallyLinkage=*/true); 2795} 2796 2797void CodeGenVTables::EmitThunks(GlobalDecl GD) 2798{ 2799 const CXXMethodDecl *MD = 2800 cast<CXXMethodDecl>(GD.getDecl())->getCanonicalDecl(); 2801 2802 // We don't need to generate thunks for the base destructor. 2803 if (isa<CXXDestructorDecl>(MD) && GD.getDtorType() == Dtor_Base) 2804 return; 2805 2806 const CXXRecordDecl *RD = MD->getParent(); 2807 2808 // Compute VTable related info for this class. 2809 ComputeVTableRelatedInformation(RD, false); 2810 2811 ThunksMapTy::const_iterator I = Thunks.find(MD); 2812 if (I == Thunks.end()) { 2813 // We did not find a thunk for this method. 2814 return; 2815 } 2816 2817 const ThunkInfoVectorTy &ThunkInfoVector = I->second; 2818 for (unsigned I = 0, E = ThunkInfoVector.size(); I != E; ++I) 2819 EmitThunk(GD, ThunkInfoVector[I], /*UseAvailableExternallyLinkage=*/false); 2820} 2821 2822void CodeGenVTables::ComputeVTableRelatedInformation(const CXXRecordDecl *RD, 2823 bool RequireVTable) { 2824 VTableLayoutData &Entry = VTableLayoutMap[RD]; 2825 2826 // We may need to generate a definition for this vtable. 2827 if (RequireVTable && !Entry.getInt()) { 2828 if (ShouldEmitVTableInThisTU(RD)) 2829 CGM.DeferredVTables.push_back(RD); 2830 2831 Entry.setInt(true); 2832 } 2833 2834 // Check if we've computed this information before. 2835 if (Entry.getPointer()) 2836 return; 2837 2838 VTableBuilder Builder(*this, RD, 0, /*MostDerivedClassIsVirtual=*/0, RD); 2839 2840 // Add the VTable layout. 2841 uint64_t NumVTableComponents = Builder.getNumVTableComponents(); 2842 // -fapple-kext adds an extra entry at end of vtbl. 2843 bool IsAppleKext = CGM.getContext().getLangOptions().AppleKext; 2844 if (IsAppleKext) 2845 NumVTableComponents += 1; 2846 2847 uint64_t *LayoutData = new uint64_t[NumVTableComponents + 1]; 2848 if (IsAppleKext) 2849 LayoutData[NumVTableComponents] = 0; 2850 Entry.setPointer(LayoutData); 2851 2852 // Store the number of components. 2853 LayoutData[0] = NumVTableComponents; 2854 2855 // Store the components. 2856 std::copy(Builder.vtable_components_data_begin(), 2857 Builder.vtable_components_data_end(), 2858 &LayoutData[1]); 2859 2860 // Add the known thunks. 2861 Thunks.insert(Builder.thunks_begin(), Builder.thunks_end()); 2862 2863 // Add the thunks needed in this vtable. 2864 assert(!VTableThunksMap.count(RD) && 2865 "Thunks already exists for this vtable!"); 2866 2867 VTableThunksTy &VTableThunks = VTableThunksMap[RD]; 2868 VTableThunks.append(Builder.vtable_thunks_begin(), 2869 Builder.vtable_thunks_end()); 2870 2871 // Sort them. 2872 std::sort(VTableThunks.begin(), VTableThunks.end()); 2873 2874 // Add the address points. 2875 for (VTableBuilder::AddressPointsMapTy::const_iterator I = 2876 Builder.address_points_begin(), E = Builder.address_points_end(); 2877 I != E; ++I) { 2878 2879 uint64_t &AddressPoint = AddressPoints[std::make_pair(RD, I->first)]; 2880 2881 // Check if we already have the address points for this base. 2882 assert(!AddressPoint && "Address point already exists for this base!"); 2883 2884 AddressPoint = I->second; 2885 } 2886 2887 // If we don't have the vbase information for this class, insert it. 2888 // getVirtualBaseOffsetOffset will compute it separately without computing 2889 // the rest of the vtable related information. 2890 if (!RD->getNumVBases()) 2891 return; 2892 2893 const RecordType *VBaseRT = 2894 RD->vbases_begin()->getType()->getAs<RecordType>(); 2895 const CXXRecordDecl *VBase = cast<CXXRecordDecl>(VBaseRT->getDecl()); 2896 2897 if (VirtualBaseClassOffsetOffsets.count(std::make_pair(RD, VBase))) 2898 return; 2899 2900 for (VTableBuilder::VBaseOffsetOffsetsMapTy::const_iterator I = 2901 Builder.getVBaseOffsetOffsets().begin(), 2902 E = Builder.getVBaseOffsetOffsets().end(); I != E; ++I) { 2903 // Insert all types. 2904 ClassPairTy ClassPair(RD, I->first); 2905 2906 VirtualBaseClassOffsetOffsets.insert(std::make_pair(ClassPair, I->second)); 2907 } 2908} 2909 2910llvm::Constant * 2911CodeGenVTables::CreateVTableInitializer(const CXXRecordDecl *RD, 2912 const uint64_t *Components, 2913 unsigned NumComponents, 2914 const VTableThunksTy &VTableThunks) { 2915 llvm::SmallVector<llvm::Constant *, 64> Inits; 2916 2917 const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGM.getLLVMContext()); 2918 2919 const llvm::Type *PtrDiffTy = 2920 CGM.getTypes().ConvertType(CGM.getContext().getPointerDiffType()); 2921 2922 QualType ClassType = CGM.getContext().getTagDeclType(RD); 2923 llvm::Constant *RTTI = CGM.GetAddrOfRTTIDescriptor(ClassType); 2924 2925 unsigned NextVTableThunkIndex = 0; 2926 2927 llvm::Constant* PureVirtualFn = 0; 2928 2929 for (unsigned I = 0; I != NumComponents; ++I) { 2930 VTableComponent Component = 2931 VTableComponent::getFromOpaqueInteger(Components[I]); 2932 2933 llvm::Constant *Init = 0; 2934 2935 switch (Component.getKind()) { 2936 case VTableComponent::CK_VCallOffset: 2937 Init = llvm::ConstantInt::get(PtrDiffTy, Component.getVCallOffset()); 2938 Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy); 2939 break; 2940 case VTableComponent::CK_VBaseOffset: 2941 Init = llvm::ConstantInt::get(PtrDiffTy, Component.getVBaseOffset()); 2942 Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy); 2943 break; 2944 case VTableComponent::CK_OffsetToTop: 2945 Init = llvm::ConstantInt::get(PtrDiffTy, Component.getOffsetToTop()); 2946 Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy); 2947 break; 2948 case VTableComponent::CK_RTTI: 2949 Init = llvm::ConstantExpr::getBitCast(RTTI, Int8PtrTy); 2950 break; 2951 case VTableComponent::CK_FunctionPointer: 2952 case VTableComponent::CK_CompleteDtorPointer: 2953 case VTableComponent::CK_DeletingDtorPointer: { 2954 GlobalDecl GD; 2955 2956 // Get the right global decl. 2957 switch (Component.getKind()) { 2958 default: 2959 llvm_unreachable("Unexpected vtable component kind"); 2960 case VTableComponent::CK_FunctionPointer: 2961 GD = Component.getFunctionDecl(); 2962 break; 2963 case VTableComponent::CK_CompleteDtorPointer: 2964 GD = GlobalDecl(Component.getDestructorDecl(), Dtor_Complete); 2965 break; 2966 case VTableComponent::CK_DeletingDtorPointer: 2967 GD = GlobalDecl(Component.getDestructorDecl(), Dtor_Deleting); 2968 break; 2969 } 2970 2971 if (cast<CXXMethodDecl>(GD.getDecl())->isPure()) { 2972 // We have a pure virtual member function. 2973 if (!PureVirtualFn) { 2974 const llvm::FunctionType *Ty = 2975 llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()), 2976 /*isVarArg=*/false); 2977 PureVirtualFn = 2978 CGM.CreateRuntimeFunction(Ty, "__cxa_pure_virtual"); 2979 PureVirtualFn = llvm::ConstantExpr::getBitCast(PureVirtualFn, 2980 Int8PtrTy); 2981 } 2982 2983 Init = PureVirtualFn; 2984 } else { 2985 // Check if we should use a thunk. 2986 if (NextVTableThunkIndex < VTableThunks.size() && 2987 VTableThunks[NextVTableThunkIndex].first == I) { 2988 const ThunkInfo &Thunk = VTableThunks[NextVTableThunkIndex].second; 2989 2990 Init = CGM.GetAddrOfThunk(GD, Thunk); 2991 MaybeEmitThunkAvailableExternally(GD, Thunk); 2992 2993 NextVTableThunkIndex++; 2994 } else { 2995 const llvm::Type *Ty = CGM.getTypes().GetFunctionTypeForVTable(GD); 2996 2997 Init = CGM.GetAddrOfFunction(GD, Ty, /*ForVTable=*/true); 2998 } 2999 3000 Init = llvm::ConstantExpr::getBitCast(Init, Int8PtrTy); 3001 } 3002 break; 3003 } 3004 3005 case VTableComponent::CK_UnusedFunctionPointer: 3006 Init = llvm::ConstantExpr::getNullValue(Int8PtrTy); 3007 break; 3008 }; 3009 3010 Inits.push_back(Init); 3011 } 3012 3013 llvm::ArrayType *ArrayType = llvm::ArrayType::get(Int8PtrTy, NumComponents); 3014 return llvm::ConstantArray::get(ArrayType, Inits.data(), Inits.size()); 3015} 3016 3017llvm::GlobalVariable *CodeGenVTables::GetAddrOfVTable(const CXXRecordDecl *RD) { 3018 llvm::SmallString<256> OutName; 3019 llvm::raw_svector_ostream Out(OutName); 3020 CGM.getCXXABI().getMangleContext().mangleCXXVTable(RD, Out); 3021 Out.flush(); 3022 llvm::StringRef Name = OutName.str(); 3023 3024 ComputeVTableRelatedInformation(RD, true); 3025 3026 const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGM.getLLVMContext()); 3027 llvm::ArrayType *ArrayType = 3028 llvm::ArrayType::get(Int8PtrTy, getNumVTableComponents(RD)); 3029 3030 llvm::GlobalVariable *GV = 3031 CGM.CreateOrReplaceCXXRuntimeVariable(Name, ArrayType, 3032 llvm::GlobalValue::ExternalLinkage); 3033 GV->setUnnamedAddr(true); 3034 return GV; 3035} 3036 3037void 3038CodeGenVTables::EmitVTableDefinition(llvm::GlobalVariable *VTable, 3039 llvm::GlobalVariable::LinkageTypes Linkage, 3040 const CXXRecordDecl *RD) { 3041 // Dump the vtable layout if necessary. 3042 if (CGM.getLangOptions().DumpVTableLayouts) { 3043 VTableBuilder Builder(*this, RD, 0, /*MostDerivedClassIsVirtual=*/0, RD); 3044 3045 Builder.dumpLayout(llvm::errs()); 3046 } 3047 3048 assert(VTableThunksMap.count(RD) && 3049 "No thunk status for this record decl!"); 3050 3051 const VTableThunksTy& Thunks = VTableThunksMap[RD]; 3052 3053 // Create and set the initializer. 3054 llvm::Constant *Init = 3055 CreateVTableInitializer(RD, getVTableComponentsData(RD), 3056 getNumVTableComponents(RD), Thunks); 3057 VTable->setInitializer(Init); 3058 3059 // Set the correct linkage. 3060 VTable->setLinkage(Linkage); 3061 3062 // Set the right visibility. 3063 CGM.setTypeVisibility(VTable, RD, CodeGenModule::TVK_ForVTable); 3064} 3065 3066llvm::GlobalVariable * 3067CodeGenVTables::GenerateConstructionVTable(const CXXRecordDecl *RD, 3068 const BaseSubobject &Base, 3069 bool BaseIsVirtual, 3070 llvm::GlobalVariable::LinkageTypes Linkage, 3071 VTableAddressPointsMapTy& AddressPoints) { 3072 VTableBuilder Builder(*this, Base.getBase(), 3073 CGM.getContext().toBits(Base.getBaseOffset()), 3074 /*MostDerivedClassIsVirtual=*/BaseIsVirtual, RD); 3075 3076 // Dump the vtable layout if necessary. 3077 if (CGM.getLangOptions().DumpVTableLayouts) 3078 Builder.dumpLayout(llvm::errs()); 3079 3080 // Add the address points. 3081 AddressPoints.insert(Builder.address_points_begin(), 3082 Builder.address_points_end()); 3083 3084 // Get the mangled construction vtable name. 3085 llvm::SmallString<256> OutName; 3086 llvm::raw_svector_ostream Out(OutName); 3087 CGM.getCXXABI().getMangleContext(). 3088 mangleCXXCtorVTable(RD, Base.getBaseOffset().getQuantity(), Base.getBase(), 3089 Out); 3090 Out.flush(); 3091 llvm::StringRef Name = OutName.str(); 3092 3093 const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGM.getLLVMContext()); 3094 llvm::ArrayType *ArrayType = 3095 llvm::ArrayType::get(Int8PtrTy, Builder.getNumVTableComponents()); 3096 3097 // Create the variable that will hold the construction vtable. 3098 llvm::GlobalVariable *VTable = 3099 CGM.CreateOrReplaceCXXRuntimeVariable(Name, ArrayType, Linkage); 3100 CGM.setTypeVisibility(VTable, RD, CodeGenModule::TVK_ForConstructionVTable); 3101 3102 // V-tables are always unnamed_addr. 3103 VTable->setUnnamedAddr(true); 3104 3105 // Add the thunks. 3106 VTableThunksTy VTableThunks; 3107 VTableThunks.append(Builder.vtable_thunks_begin(), 3108 Builder.vtable_thunks_end()); 3109 3110 // Sort them. 3111 std::sort(VTableThunks.begin(), VTableThunks.end()); 3112 3113 // Create and set the initializer. 3114 llvm::Constant *Init = 3115 CreateVTableInitializer(Base.getBase(), 3116 Builder.vtable_components_data_begin(), 3117 Builder.getNumVTableComponents(), VTableThunks); 3118 VTable->setInitializer(Init); 3119 3120 return VTable; 3121} 3122 3123void 3124CodeGenVTables::GenerateClassData(llvm::GlobalVariable::LinkageTypes Linkage, 3125 const CXXRecordDecl *RD) { 3126 llvm::GlobalVariable *&VTable = VTables[RD]; 3127 if (VTable) { 3128 assert(VTable->getInitializer() && "VTable doesn't have a definition!"); 3129 return; 3130 } 3131 3132 VTable = GetAddrOfVTable(RD); 3133 EmitVTableDefinition(VTable, Linkage, RD); 3134 3135 if (RD->getNumVBases()) { 3136 llvm::GlobalVariable *VTT = GetAddrOfVTT(RD); 3137 EmitVTTDefinition(VTT, Linkage, RD); 3138 } 3139 3140 // If this is the magic class __cxxabiv1::__fundamental_type_info, 3141 // we will emit the typeinfo for the fundamental types. This is the 3142 // same behaviour as GCC. 3143 const DeclContext *DC = RD->getDeclContext(); 3144 if (RD->getIdentifier() && 3145 RD->getIdentifier()->isStr("__fundamental_type_info") && 3146 isa<NamespaceDecl>(DC) && 3147 cast<NamespaceDecl>(DC)->getIdentifier() && 3148 cast<NamespaceDecl>(DC)->getIdentifier()->isStr("__cxxabiv1") && 3149 DC->getParent()->isTranslationUnit()) 3150 CGM.EmitFundamentalRTTIDescriptors(); 3151} 3152