CGVTables.cpp revision bb625e9692e5b8d839f64208b8fa29684c668f8b
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 CharUnits RealBaseOffset); 747 748 /// AddVCallOffsets - Add vcall offsets for the given base subobject. 749 void AddVCallOffsets(BaseSubobject Base, CharUnits VBaseOffset); 750 751 /// AddVBaseOffsets - Add vbase offsets for the given class. 752 void AddVBaseOffsets(const CXXRecordDecl *Base, 753 CharUnits OffsetInLayoutClass); 754 755 /// getCurrentOffsetOffset - Get the current vcall or vbase offset offset in 756 /// bytes, relative to the vtable address point. 757 int64_t getCurrentOffsetOffset() const; 758 759public: 760 VCallAndVBaseOffsetBuilder(const CXXRecordDecl *MostDerivedClass, 761 const CXXRecordDecl *LayoutClass, 762 const FinalOverriders *Overriders, 763 BaseSubobject Base, bool BaseIsVirtual, 764 CharUnits OffsetInLayoutClass) 765 : MostDerivedClass(MostDerivedClass), LayoutClass(LayoutClass), 766 Context(MostDerivedClass->getASTContext()), Overriders(Overriders) { 767 768 // Add vcall and vbase offsets. 769 AddVCallAndVBaseOffsets(Base, BaseIsVirtual, OffsetInLayoutClass); 770 } 771 772 /// Methods for iterating over the components. 773 typedef VTableComponentVectorTy::const_reverse_iterator const_iterator; 774 const_iterator components_begin() const { return Components.rbegin(); } 775 const_iterator components_end() const { return Components.rend(); } 776 777 const VCallOffsetMap &getVCallOffsets() const { return VCallOffsets; } 778 const VBaseOffsetOffsetsMapTy &getVBaseOffsetOffsets() const { 779 return VBaseOffsetOffsets; 780 } 781}; 782 783void 784VCallAndVBaseOffsetBuilder::AddVCallAndVBaseOffsets(BaseSubobject Base, 785 bool BaseIsVirtual, 786 CharUnits RealBaseOffset) { 787 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base.getBase()); 788 789 // Itanium C++ ABI 2.5.2: 790 // ..in classes sharing a virtual table with a primary base class, the vcall 791 // and vbase offsets added by the derived class all come before the vcall 792 // and vbase offsets required by the base class, so that the latter may be 793 // laid out as required by the base class without regard to additions from 794 // the derived class(es). 795 796 // (Since we're emitting the vcall and vbase offsets in reverse order, we'll 797 // emit them for the primary base first). 798 if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) { 799 bool PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual(); 800 801 CharUnits PrimaryBaseOffset; 802 803 // Get the base offset of the primary base. 804 if (PrimaryBaseIsVirtual) { 805 assert(Layout.getVBaseClassOffsetInBits(PrimaryBase) == 0 && 806 "Primary vbase should have a zero offset!"); 807 808 const ASTRecordLayout &MostDerivedClassLayout = 809 Context.getASTRecordLayout(MostDerivedClass); 810 811 PrimaryBaseOffset = 812 MostDerivedClassLayout.getVBaseClassOffset(PrimaryBase); 813 } else { 814 assert(Layout.getBaseClassOffsetInBits(PrimaryBase) == 0 && 815 "Primary base should have a zero offset!"); 816 817 PrimaryBaseOffset = Base.getBaseOffset(); 818 } 819 820 AddVCallAndVBaseOffsets( 821 BaseSubobject(PrimaryBase,PrimaryBaseOffset), 822 PrimaryBaseIsVirtual, RealBaseOffset); 823 } 824 825 AddVBaseOffsets(Base.getBase(), RealBaseOffset); 826 827 // We only want to add vcall offsets for virtual bases. 828 if (BaseIsVirtual) 829 AddVCallOffsets(Base, RealBaseOffset); 830} 831 832int64_t VCallAndVBaseOffsetBuilder::getCurrentOffsetOffset() const { 833 // OffsetIndex is the index of this vcall or vbase offset, relative to the 834 // vtable address point. (We subtract 3 to account for the information just 835 // above the address point, the RTTI info, the offset to top, and the 836 // vcall offset itself). 837 int64_t OffsetIndex = -(int64_t)(3 + Components.size()); 838 839 // FIXME: We shouldn't use / 8 here. 840 int64_t OffsetOffset = OffsetIndex * 841 (int64_t)Context.Target.getPointerWidth(0) / 8; 842 843 return OffsetOffset; 844} 845 846void VCallAndVBaseOffsetBuilder::AddVCallOffsets(BaseSubobject Base, 847 CharUnits VBaseOffset) { 848 const CXXRecordDecl *RD = Base.getBase(); 849 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); 850 851 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase(); 852 853 // Handle the primary base first. 854 // We only want to add vcall offsets if the base is non-virtual; a virtual 855 // primary base will have its vcall and vbase offsets emitted already. 856 if (PrimaryBase && !Layout.isPrimaryBaseVirtual()) { 857 // Get the base offset of the primary base. 858 assert(Layout.getBaseClassOffsetInBits(PrimaryBase) == 0 && 859 "Primary base should have a zero offset!"); 860 861 AddVCallOffsets(BaseSubobject(PrimaryBase, Base.getBaseOffset()), 862 VBaseOffset); 863 } 864 865 // Add the vcall offsets. 866 for (CXXRecordDecl::method_iterator I = RD->method_begin(), 867 E = RD->method_end(); I != E; ++I) { 868 const CXXMethodDecl *MD = *I; 869 870 if (!MD->isVirtual()) 871 continue; 872 873 int64_t OffsetOffset = getCurrentOffsetOffset(); 874 875 // Don't add a vcall offset if we already have one for this member function 876 // signature. 877 if (!VCallOffsets.AddVCallOffset(MD, OffsetOffset)) 878 continue; 879 880 CharUnits Offset = CharUnits::Zero(); 881 882 if (Overriders) { 883 // Get the final overrider. 884 FinalOverriders::OverriderInfo Overrider = 885 Overriders->getOverrider(MD, Base.getBaseOffset()); 886 887 /// The vcall offset is the offset from the virtual base to the object 888 /// where the function was overridden. 889 Offset = Overrider.Offset - VBaseOffset; 890 } 891 892 Components.push_back( 893 VTableComponent::MakeVCallOffset(Offset.getQuantity())); 894 } 895 896 // And iterate over all non-virtual bases (ignoring the primary base). 897 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), 898 E = RD->bases_end(); I != E; ++I) { 899 900 if (I->isVirtual()) 901 continue; 902 903 const CXXRecordDecl *BaseDecl = 904 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); 905 if (BaseDecl == PrimaryBase) 906 continue; 907 908 // Get the base offset of this base. 909 CharUnits BaseOffset = Base.getBaseOffset() + 910 Layout.getBaseClassOffset(BaseDecl); 911 912 AddVCallOffsets(BaseSubobject(BaseDecl, BaseOffset), 913 VBaseOffset); 914 } 915} 916 917void 918VCallAndVBaseOffsetBuilder::AddVBaseOffsets(const CXXRecordDecl *RD, 919 CharUnits OffsetInLayoutClass) { 920 const ASTRecordLayout &LayoutClassLayout = 921 Context.getASTRecordLayout(LayoutClass); 922 923 // Add vbase offsets. 924 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), 925 E = RD->bases_end(); I != E; ++I) { 926 const CXXRecordDecl *BaseDecl = 927 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); 928 929 // Check if this is a virtual base that we haven't visited before. 930 if (I->isVirtual() && VisitedVirtualBases.insert(BaseDecl)) { 931 CharUnits Offset = 932 LayoutClassLayout.getVBaseClassOffset(BaseDecl) - OffsetInLayoutClass; 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( 942 VTableComponent::MakeVBaseOffset(Offset.getQuantity())); 943 } 944 945 // Check the base class looking for more vbase offsets. 946 AddVBaseOffsets(BaseDecl, OffsetInLayoutClass); 947 } 948} 949 950/// VTableBuilder - Class for building vtable layout information. 951class VTableBuilder { 952public: 953 /// PrimaryBasesSetVectorTy - A set vector of direct and indirect 954 /// primary bases. 955 typedef llvm::SmallSetVector<const CXXRecordDecl *, 8> 956 PrimaryBasesSetVectorTy; 957 958 typedef llvm::DenseMap<const CXXRecordDecl *, int64_t> 959 VBaseOffsetOffsetsMapTy; 960 961 typedef llvm::DenseMap<BaseSubobject, uint64_t> 962 AddressPointsMapTy; 963 964private: 965 /// VTables - Global vtable information. 966 CodeGenVTables &VTables; 967 968 /// MostDerivedClass - The most derived class for which we're building this 969 /// vtable. 970 const CXXRecordDecl *MostDerivedClass; 971 972 /// MostDerivedClassOffset - If we're building a construction vtable, this 973 /// holds the offset from the layout class to the most derived class. 974 const CharUnits MostDerivedClassOffset; 975 976 /// MostDerivedClassIsVirtual - Whether the most derived class is a virtual 977 /// base. (This only makes sense when building a construction vtable). 978 bool MostDerivedClassIsVirtual; 979 980 /// LayoutClass - The class we're using for layout information. Will be 981 /// different than the most derived class if we're building a construction 982 /// vtable. 983 const CXXRecordDecl *LayoutClass; 984 985 /// Context - The ASTContext which we will use for layout information. 986 ASTContext &Context; 987 988 /// FinalOverriders - The final overriders of the most derived class. 989 const FinalOverriders Overriders; 990 991 /// VCallOffsetsForVBases - Keeps track of vcall offsets for the virtual 992 /// bases in this vtable. 993 llvm::DenseMap<const CXXRecordDecl *, VCallOffsetMap> VCallOffsetsForVBases; 994 995 /// VBaseOffsetOffsets - Contains the offsets of the virtual base offsets for 996 /// the most derived class. 997 VBaseOffsetOffsetsMapTy VBaseOffsetOffsets; 998 999 /// Components - The components of the vtable being built. 1000 llvm::SmallVector<VTableComponent, 64> Components; 1001 1002 /// AddressPoints - Address points for the vtable being built. 1003 AddressPointsMapTy AddressPoints; 1004 1005 /// MethodInfo - Contains information about a method in a vtable. 1006 /// (Used for computing 'this' pointer adjustment thunks. 1007 struct MethodInfo { 1008 /// BaseOffset - The base offset of this method. 1009 const CharUnits BaseOffset; 1010 1011 /// BaseOffsetInLayoutClass - The base offset in the layout class of this 1012 /// method. 1013 const CharUnits BaseOffsetInLayoutClass; 1014 1015 /// VTableIndex - The index in the vtable that this method has. 1016 /// (For destructors, this is the index of the complete destructor). 1017 const uint64_t VTableIndex; 1018 1019 MethodInfo(CharUnits BaseOffset, CharUnits BaseOffsetInLayoutClass, 1020 uint64_t VTableIndex) 1021 : BaseOffset(BaseOffset), 1022 BaseOffsetInLayoutClass(BaseOffsetInLayoutClass), 1023 VTableIndex(VTableIndex) { } 1024 1025 MethodInfo() 1026 : BaseOffset(CharUnits::Zero()), 1027 BaseOffsetInLayoutClass(CharUnits::Zero()), 1028 VTableIndex(0) { } 1029 }; 1030 1031 typedef llvm::DenseMap<const CXXMethodDecl *, MethodInfo> MethodInfoMapTy; 1032 1033 /// MethodInfoMap - The information for all methods in the vtable we're 1034 /// currently building. 1035 MethodInfoMapTy MethodInfoMap; 1036 1037 typedef llvm::DenseMap<uint64_t, ThunkInfo> VTableThunksMapTy; 1038 1039 /// VTableThunks - The thunks by vtable index in the vtable currently being 1040 /// built. 1041 VTableThunksMapTy VTableThunks; 1042 1043 typedef llvm::SmallVector<ThunkInfo, 1> ThunkInfoVectorTy; 1044 typedef llvm::DenseMap<const CXXMethodDecl *, ThunkInfoVectorTy> ThunksMapTy; 1045 1046 /// Thunks - A map that contains all the thunks needed for all methods in the 1047 /// most derived class for which the vtable is currently being built. 1048 ThunksMapTy Thunks; 1049 1050 /// AddThunk - Add a thunk for the given method. 1051 void AddThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk); 1052 1053 /// ComputeThisAdjustments - Compute the 'this' pointer adjustments for the 1054 /// part of the vtable we're currently building. 1055 void ComputeThisAdjustments(); 1056 1057 typedef llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBasesSetTy; 1058 1059 /// PrimaryVirtualBases - All known virtual bases who are a primary base of 1060 /// some other base. 1061 VisitedVirtualBasesSetTy PrimaryVirtualBases; 1062 1063 /// ComputeReturnAdjustment - Compute the return adjustment given a return 1064 /// adjustment base offset. 1065 ReturnAdjustment ComputeReturnAdjustment(BaseOffset Offset); 1066 1067 /// ComputeThisAdjustmentBaseOffset - Compute the base offset for adjusting 1068 /// the 'this' pointer from the base subobject to the derived subobject. 1069 BaseOffset ComputeThisAdjustmentBaseOffset(BaseSubobject Base, 1070 BaseSubobject Derived) const; 1071 1072 /// ComputeThisAdjustment - Compute the 'this' pointer adjustment for the 1073 /// given virtual member function, its offset in the layout class and its 1074 /// final overrider. 1075 ThisAdjustment 1076 ComputeThisAdjustment(const CXXMethodDecl *MD, 1077 CharUnits BaseOffsetInLayoutClass, 1078 FinalOverriders::OverriderInfo Overrider); 1079 1080 /// AddMethod - Add a single virtual member function to the vtable 1081 /// components vector. 1082 void AddMethod(const CXXMethodDecl *MD, ReturnAdjustment ReturnAdjustment); 1083 1084 /// IsOverriderUsed - Returns whether the overrider will ever be used in this 1085 /// part of the vtable. 1086 /// 1087 /// Itanium C++ ABI 2.5.2: 1088 /// 1089 /// struct A { virtual void f(); }; 1090 /// struct B : virtual public A { int i; }; 1091 /// struct C : virtual public A { int j; }; 1092 /// struct D : public B, public C {}; 1093 /// 1094 /// When B and C are declared, A is a primary base in each case, so although 1095 /// vcall offsets are allocated in the A-in-B and A-in-C vtables, no this 1096 /// adjustment is required and no thunk is generated. However, inside D 1097 /// objects, A is no longer a primary base of C, so if we allowed calls to 1098 /// C::f() to use the copy of A's vtable in the C subobject, we would need 1099 /// to adjust this from C* to B::A*, which would require a third-party 1100 /// thunk. Since we require that a call to C::f() first convert to A*, 1101 /// C-in-D's copy of A's vtable is never referenced, so this is not 1102 /// necessary. 1103 bool IsOverriderUsed(const CXXMethodDecl *Overrider, 1104 uint64_t BaseOffsetInLayoutClass, 1105 const CXXRecordDecl *FirstBaseInPrimaryBaseChain, 1106 uint64_t FirstBaseOffsetInLayoutClass) const; 1107 1108 1109 /// AddMethods - Add the methods of this base subobject and all its 1110 /// primary bases to the vtable components vector. 1111 void AddMethods(BaseSubobject Base, CharUnits BaseOffsetInLayoutClass, 1112 const CXXRecordDecl *FirstBaseInPrimaryBaseChain, 1113 CharUnits FirstBaseOffsetInLayoutClass, 1114 PrimaryBasesSetVectorTy &PrimaryBases); 1115 1116 // LayoutVTable - Layout the vtable for the given base class, including its 1117 // secondary vtables and any vtables for virtual bases. 1118 void LayoutVTable(); 1119 1120 /// LayoutPrimaryAndSecondaryVTables - Layout the primary vtable for the 1121 /// given base subobject, as well as all its secondary vtables. 1122 /// 1123 /// \param BaseIsMorallyVirtual whether the base subobject is a virtual base 1124 /// or a direct or indirect base of a virtual base. 1125 /// 1126 /// \param BaseIsVirtualInLayoutClass - Whether the base subobject is virtual 1127 /// in the layout class. 1128 void LayoutPrimaryAndSecondaryVTables(BaseSubobject Base, 1129 bool BaseIsMorallyVirtual, 1130 bool BaseIsVirtualInLayoutClass, 1131 CharUnits OffsetInLayoutClass); 1132 1133 /// LayoutSecondaryVTables - Layout the secondary vtables for the given base 1134 /// subobject. 1135 /// 1136 /// \param BaseIsMorallyVirtual whether the base subobject is a virtual base 1137 /// or a direct or indirect base of a virtual base. 1138 void LayoutSecondaryVTables(BaseSubobject Base, bool BaseIsMorallyVirtual, 1139 CharUnits OffsetInLayoutClass); 1140 1141 /// DeterminePrimaryVirtualBases - Determine the primary virtual bases in this 1142 /// class hierarchy. 1143 void DeterminePrimaryVirtualBases(const CXXRecordDecl *RD, 1144 CharUnits OffsetInLayoutClass, 1145 VisitedVirtualBasesSetTy &VBases); 1146 1147 /// LayoutVTablesForVirtualBases - Layout vtables for all virtual bases of the 1148 /// given base (excluding any primary bases). 1149 void LayoutVTablesForVirtualBases(const CXXRecordDecl *RD, 1150 VisitedVirtualBasesSetTy &VBases); 1151 1152 /// isBuildingConstructionVTable - Return whether this vtable builder is 1153 /// building a construction vtable. 1154 bool isBuildingConstructorVTable() const { 1155 return MostDerivedClass != LayoutClass; 1156 } 1157 1158public: 1159 VTableBuilder(CodeGenVTables &VTables, const CXXRecordDecl *MostDerivedClass, 1160 CharUnits MostDerivedClassOffset, 1161 bool MostDerivedClassIsVirtual, const 1162 CXXRecordDecl *LayoutClass) 1163 : VTables(VTables), MostDerivedClass(MostDerivedClass), 1164 MostDerivedClassOffset(MostDerivedClassOffset), 1165 MostDerivedClassIsVirtual(MostDerivedClassIsVirtual), 1166 LayoutClass(LayoutClass), Context(MostDerivedClass->getASTContext()), 1167 Overriders(MostDerivedClass, MostDerivedClassOffset, LayoutClass) { 1168 1169 LayoutVTable(); 1170 } 1171 1172 ThunksMapTy::const_iterator thunks_begin() const { 1173 return Thunks.begin(); 1174 } 1175 1176 ThunksMapTy::const_iterator thunks_end() const { 1177 return Thunks.end(); 1178 } 1179 1180 const VBaseOffsetOffsetsMapTy &getVBaseOffsetOffsets() const { 1181 return VBaseOffsetOffsets; 1182 } 1183 1184 /// getNumVTableComponents - Return the number of components in the vtable 1185 /// currently built. 1186 uint64_t getNumVTableComponents() const { 1187 return Components.size(); 1188 } 1189 1190 const uint64_t *vtable_components_data_begin() const { 1191 return reinterpret_cast<const uint64_t *>(Components.begin()); 1192 } 1193 1194 const uint64_t *vtable_components_data_end() const { 1195 return reinterpret_cast<const uint64_t *>(Components.end()); 1196 } 1197 1198 AddressPointsMapTy::const_iterator address_points_begin() const { 1199 return AddressPoints.begin(); 1200 } 1201 1202 AddressPointsMapTy::const_iterator address_points_end() const { 1203 return AddressPoints.end(); 1204 } 1205 1206 VTableThunksMapTy::const_iterator vtable_thunks_begin() const { 1207 return VTableThunks.begin(); 1208 } 1209 1210 VTableThunksMapTy::const_iterator vtable_thunks_end() const { 1211 return VTableThunks.end(); 1212 } 1213 1214 /// dumpLayout - Dump the vtable layout. 1215 void dumpLayout(llvm::raw_ostream&); 1216}; 1217 1218void VTableBuilder::AddThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk) { 1219 assert(!isBuildingConstructorVTable() && 1220 "Can't add thunks for construction vtable"); 1221 1222 llvm::SmallVector<ThunkInfo, 1> &ThunksVector = Thunks[MD]; 1223 1224 // Check if we have this thunk already. 1225 if (std::find(ThunksVector.begin(), ThunksVector.end(), Thunk) != 1226 ThunksVector.end()) 1227 return; 1228 1229 ThunksVector.push_back(Thunk); 1230} 1231 1232typedef llvm::SmallPtrSet<const CXXMethodDecl *, 8> OverriddenMethodsSetTy; 1233 1234/// ComputeAllOverriddenMethods - Given a method decl, will return a set of all 1235/// the overridden methods that the function decl overrides. 1236static void 1237ComputeAllOverriddenMethods(const CXXMethodDecl *MD, 1238 OverriddenMethodsSetTy& OverriddenMethods) { 1239 assert(MD->isVirtual() && "Method is not virtual!"); 1240 1241 for (CXXMethodDecl::method_iterator I = MD->begin_overridden_methods(), 1242 E = MD->end_overridden_methods(); I != E; ++I) { 1243 const CXXMethodDecl *OverriddenMD = *I; 1244 1245 OverriddenMethods.insert(OverriddenMD); 1246 1247 ComputeAllOverriddenMethods(OverriddenMD, OverriddenMethods); 1248 } 1249} 1250 1251void VTableBuilder::ComputeThisAdjustments() { 1252 // Now go through the method info map and see if any of the methods need 1253 // 'this' pointer adjustments. 1254 for (MethodInfoMapTy::const_iterator I = MethodInfoMap.begin(), 1255 E = MethodInfoMap.end(); I != E; ++I) { 1256 const CXXMethodDecl *MD = I->first; 1257 const MethodInfo &MethodInfo = I->second; 1258 1259 // Ignore adjustments for unused function pointers. 1260 uint64_t VTableIndex = MethodInfo.VTableIndex; 1261 if (Components[VTableIndex].getKind() == 1262 VTableComponent::CK_UnusedFunctionPointer) 1263 continue; 1264 1265 // Get the final overrider for this method. 1266 FinalOverriders::OverriderInfo Overrider = 1267 Overriders.getOverrider(MD, MethodInfo.BaseOffset); 1268 1269 // Check if we need an adjustment at all. 1270 if (MethodInfo.BaseOffsetInLayoutClass == Overrider.Offset) { 1271 // When a return thunk is needed by a derived class that overrides a 1272 // virtual base, gcc uses a virtual 'this' adjustment as well. 1273 // While the thunk itself might be needed by vtables in subclasses or 1274 // in construction vtables, there doesn't seem to be a reason for using 1275 // the thunk in this vtable. Still, we do so to match gcc. 1276 if (VTableThunks.lookup(VTableIndex).Return.isEmpty()) 1277 continue; 1278 } 1279 1280 ThisAdjustment ThisAdjustment = 1281 ComputeThisAdjustment(MD, MethodInfo.BaseOffsetInLayoutClass, Overrider); 1282 1283 if (ThisAdjustment.isEmpty()) 1284 continue; 1285 1286 // Add it. 1287 VTableThunks[VTableIndex].This = ThisAdjustment; 1288 1289 if (isa<CXXDestructorDecl>(MD)) { 1290 // Add an adjustment for the deleting destructor as well. 1291 VTableThunks[VTableIndex + 1].This = ThisAdjustment; 1292 } 1293 } 1294 1295 /// Clear the method info map. 1296 MethodInfoMap.clear(); 1297 1298 if (isBuildingConstructorVTable()) { 1299 // We don't need to store thunk information for construction vtables. 1300 return; 1301 } 1302 1303 for (VTableThunksMapTy::const_iterator I = VTableThunks.begin(), 1304 E = VTableThunks.end(); I != E; ++I) { 1305 const VTableComponent &Component = Components[I->first]; 1306 const ThunkInfo &Thunk = I->second; 1307 const CXXMethodDecl *MD; 1308 1309 switch (Component.getKind()) { 1310 default: 1311 llvm_unreachable("Unexpected vtable component kind!"); 1312 case VTableComponent::CK_FunctionPointer: 1313 MD = Component.getFunctionDecl(); 1314 break; 1315 case VTableComponent::CK_CompleteDtorPointer: 1316 MD = Component.getDestructorDecl(); 1317 break; 1318 case VTableComponent::CK_DeletingDtorPointer: 1319 // We've already added the thunk when we saw the complete dtor pointer. 1320 continue; 1321 } 1322 1323 if (MD->getParent() == MostDerivedClass) 1324 AddThunk(MD, Thunk); 1325 } 1326} 1327 1328ReturnAdjustment VTableBuilder::ComputeReturnAdjustment(BaseOffset Offset) { 1329 ReturnAdjustment Adjustment; 1330 1331 if (!Offset.isEmpty()) { 1332 if (Offset.VirtualBase) { 1333 // Get the virtual base offset offset. 1334 if (Offset.DerivedClass == MostDerivedClass) { 1335 // We can get the offset offset directly from our map. 1336 Adjustment.VBaseOffsetOffset = 1337 VBaseOffsetOffsets.lookup(Offset.VirtualBase); 1338 } else { 1339 Adjustment.VBaseOffsetOffset = 1340 VTables.getVirtualBaseOffsetOffset(Offset.DerivedClass, 1341 Offset.VirtualBase); 1342 } 1343 } 1344 1345 Adjustment.NonVirtual = Offset.NonVirtualOffset; 1346 } 1347 1348 return Adjustment; 1349} 1350 1351BaseOffset 1352VTableBuilder::ComputeThisAdjustmentBaseOffset(BaseSubobject Base, 1353 BaseSubobject Derived) const { 1354 const CXXRecordDecl *BaseRD = Base.getBase(); 1355 const CXXRecordDecl *DerivedRD = Derived.getBase(); 1356 1357 CXXBasePaths Paths(/*FindAmbiguities=*/true, 1358 /*RecordPaths=*/true, /*DetectVirtual=*/true); 1359 1360 if (!const_cast<CXXRecordDecl *>(DerivedRD)-> 1361 isDerivedFrom(const_cast<CXXRecordDecl *>(BaseRD), Paths)) { 1362 assert(false && "Class must be derived from the passed in base class!"); 1363 return BaseOffset(); 1364 } 1365 1366 // We have to go through all the paths, and see which one leads us to the 1367 // right base subobject. 1368 for (CXXBasePaths::const_paths_iterator I = Paths.begin(), E = Paths.end(); 1369 I != E; ++I) { 1370 BaseOffset Offset = ComputeBaseOffset(Context, DerivedRD, *I); 1371 1372 CharUnits OffsetToBaseSubobject = 1373 CharUnits::fromQuantity(Offset.NonVirtualOffset); 1374 1375 if (Offset.VirtualBase) { 1376 // If we have a virtual base class, the non-virtual offset is relative 1377 // to the virtual base class offset. 1378 const ASTRecordLayout &LayoutClassLayout = 1379 Context.getASTRecordLayout(LayoutClass); 1380 1381 /// Get the virtual base offset, relative to the most derived class 1382 /// layout. 1383 OffsetToBaseSubobject += 1384 LayoutClassLayout.getVBaseClassOffset(Offset.VirtualBase); 1385 } else { 1386 // Otherwise, the non-virtual offset is relative to the derived class 1387 // offset. 1388 OffsetToBaseSubobject += Derived.getBaseOffset(); 1389 } 1390 1391 // Check if this path gives us the right base subobject. 1392 if (OffsetToBaseSubobject == Base.getBaseOffset()) { 1393 // Since we're going from the base class _to_ the derived class, we'll 1394 // invert the non-virtual offset here. 1395 Offset.NonVirtualOffset = -Offset.NonVirtualOffset; 1396 return Offset; 1397 } 1398 } 1399 1400 return BaseOffset(); 1401} 1402 1403ThisAdjustment 1404VTableBuilder::ComputeThisAdjustment(const CXXMethodDecl *MD, 1405 CharUnits BaseOffsetInLayoutClass, 1406 FinalOverriders::OverriderInfo Overrider) { 1407 // Ignore adjustments for pure virtual member functions. 1408 if (Overrider.Method->isPure()) 1409 return ThisAdjustment(); 1410 1411 BaseSubobject OverriddenBaseSubobject(MD->getParent(), 1412 BaseOffsetInLayoutClass); 1413 1414 BaseSubobject OverriderBaseSubobject(Overrider.Method->getParent(), 1415 Overrider.Offset); 1416 1417 // Compute the adjustment offset. 1418 BaseOffset Offset = ComputeThisAdjustmentBaseOffset(OverriddenBaseSubobject, 1419 OverriderBaseSubobject); 1420 if (Offset.isEmpty()) 1421 return ThisAdjustment(); 1422 1423 ThisAdjustment Adjustment; 1424 1425 if (Offset.VirtualBase) { 1426 // Get the vcall offset map for this virtual base. 1427 VCallOffsetMap &VCallOffsets = VCallOffsetsForVBases[Offset.VirtualBase]; 1428 1429 if (VCallOffsets.empty()) { 1430 // We don't have vcall offsets for this virtual base, go ahead and 1431 // build them. 1432 VCallAndVBaseOffsetBuilder Builder(MostDerivedClass, MostDerivedClass, 1433 /*FinalOverriders=*/0, 1434 BaseSubobject(Offset.VirtualBase, 1435 CharUnits::Zero()), 1436 /*BaseIsVirtual=*/true, 1437 /*OffsetInLayoutClass=*/ 1438 CharUnits::Zero()); 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 CharUnits 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 CharUnits OffsetToTop = MostDerivedClassOffset - OffsetInLayoutClass; 1773 Components.push_back( 1774 VTableComponent::MakeOffsetToTop(OffsetToTop.getQuantity())); 1775 1776 // Next, add the RTTI. 1777 Components.push_back(VTableComponent::MakeRTTI(MostDerivedClass)); 1778 1779 uint64_t AddressPoint = Components.size(); 1780 1781 // Now go through all virtual member functions and add them. 1782 PrimaryBasesSetVectorTy PrimaryBases; 1783 AddMethods(Base, OffsetInLayoutClass, 1784 Base.getBase(), OffsetInLayoutClass, 1785 PrimaryBases); 1786 1787 // Compute 'this' pointer adjustments. 1788 ComputeThisAdjustments(); 1789 1790 // Add all address points. 1791 const CXXRecordDecl *RD = Base.getBase(); 1792 while (true) { 1793 AddressPoints.insert(std::make_pair( 1794 BaseSubobject(RD, OffsetInLayoutClass), 1795 AddressPoint)); 1796 1797 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); 1798 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase(); 1799 1800 if (!PrimaryBase) 1801 break; 1802 1803 if (Layout.isPrimaryBaseVirtual()) { 1804 // Check if this virtual primary base is a primary base in the layout 1805 // class. If it's not, we don't want to add it. 1806 const ASTRecordLayout &LayoutClassLayout = 1807 Context.getASTRecordLayout(LayoutClass); 1808 1809 if (LayoutClassLayout.getVBaseClassOffset(PrimaryBase) != 1810 OffsetInLayoutClass) { 1811 // We don't want to add this class (or any of its primary bases). 1812 break; 1813 } 1814 } 1815 1816 RD = PrimaryBase; 1817 } 1818 1819 // Layout secondary vtables. 1820 LayoutSecondaryVTables(Base, BaseIsMorallyVirtual, OffsetInLayoutClass); 1821} 1822 1823void VTableBuilder::LayoutSecondaryVTables(BaseSubobject Base, 1824 bool BaseIsMorallyVirtual, 1825 CharUnits OffsetInLayoutClass) { 1826 // Itanium C++ ABI 2.5.2: 1827 // Following the primary virtual table of a derived class are secondary 1828 // virtual tables for each of its proper base classes, except any primary 1829 // base(s) with which it shares its primary virtual table. 1830 1831 const CXXRecordDecl *RD = Base.getBase(); 1832 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); 1833 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase(); 1834 1835 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), 1836 E = RD->bases_end(); I != E; ++I) { 1837 // Ignore virtual bases, we'll emit them later. 1838 if (I->isVirtual()) 1839 continue; 1840 1841 const CXXRecordDecl *BaseDecl = 1842 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); 1843 1844 // Ignore bases that don't have a vtable. 1845 if (!BaseDecl->isDynamicClass()) 1846 continue; 1847 1848 if (isBuildingConstructorVTable()) { 1849 // Itanium C++ ABI 2.6.4: 1850 // Some of the base class subobjects may not need construction virtual 1851 // tables, which will therefore not be present in the construction 1852 // virtual table group, even though the subobject virtual tables are 1853 // present in the main virtual table group for the complete object. 1854 if (!BaseIsMorallyVirtual && !BaseDecl->getNumVBases()) 1855 continue; 1856 } 1857 1858 // Get the base offset of this base. 1859 CharUnits RelativeBaseOffset = Layout.getBaseClassOffset(BaseDecl); 1860 CharUnits BaseOffset = Base.getBaseOffset() + RelativeBaseOffset; 1861 1862 CharUnits BaseOffsetInLayoutClass = 1863 OffsetInLayoutClass + RelativeBaseOffset; 1864 1865 // Don't emit a secondary vtable for a primary base. We might however want 1866 // to emit secondary vtables for other bases of this base. 1867 if (BaseDecl == PrimaryBase) { 1868 LayoutSecondaryVTables(BaseSubobject(BaseDecl, BaseOffset), 1869 BaseIsMorallyVirtual, BaseOffsetInLayoutClass); 1870 continue; 1871 } 1872 1873 // Layout the primary vtable (and any secondary vtables) for this base. 1874 LayoutPrimaryAndSecondaryVTables( 1875 BaseSubobject(BaseDecl, BaseOffset), 1876 BaseIsMorallyVirtual, 1877 /*BaseIsVirtualInLayoutClass=*/false, 1878 BaseOffsetInLayoutClass); 1879 } 1880} 1881 1882void 1883VTableBuilder::DeterminePrimaryVirtualBases(const CXXRecordDecl *RD, 1884 CharUnits OffsetInLayoutClass, 1885 VisitedVirtualBasesSetTy &VBases) { 1886 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); 1887 1888 // Check if this base has a primary base. 1889 if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) { 1890 1891 // Check if it's virtual. 1892 if (Layout.isPrimaryBaseVirtual()) { 1893 bool IsPrimaryVirtualBase = true; 1894 1895 if (isBuildingConstructorVTable()) { 1896 // Check if the base is actually a primary base in the class we use for 1897 // layout. 1898 const ASTRecordLayout &LayoutClassLayout = 1899 Context.getASTRecordLayout(LayoutClass); 1900 1901 CharUnits PrimaryBaseOffsetInLayoutClass = 1902 LayoutClassLayout.getVBaseClassOffset(PrimaryBase); 1903 1904 // We know that the base is not a primary base in the layout class if 1905 // the base offsets are different. 1906 if (PrimaryBaseOffsetInLayoutClass != OffsetInLayoutClass) 1907 IsPrimaryVirtualBase = false; 1908 } 1909 1910 if (IsPrimaryVirtualBase) 1911 PrimaryVirtualBases.insert(PrimaryBase); 1912 } 1913 } 1914 1915 // Traverse bases, looking for more primary virtual bases. 1916 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), 1917 E = RD->bases_end(); I != E; ++I) { 1918 const CXXRecordDecl *BaseDecl = 1919 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); 1920 1921 CharUnits BaseOffsetInLayoutClass; 1922 1923 if (I->isVirtual()) { 1924 if (!VBases.insert(BaseDecl)) 1925 continue; 1926 1927 const ASTRecordLayout &LayoutClassLayout = 1928 Context.getASTRecordLayout(LayoutClass); 1929 1930 BaseOffsetInLayoutClass = 1931 LayoutClassLayout.getVBaseClassOffset(BaseDecl); 1932 } else { 1933 BaseOffsetInLayoutClass = 1934 OffsetInLayoutClass + Layout.getBaseClassOffset(BaseDecl); 1935 } 1936 1937 DeterminePrimaryVirtualBases(BaseDecl, BaseOffsetInLayoutClass, VBases); 1938 } 1939} 1940 1941void 1942VTableBuilder::LayoutVTablesForVirtualBases(const CXXRecordDecl *RD, 1943 VisitedVirtualBasesSetTy &VBases) { 1944 // Itanium C++ ABI 2.5.2: 1945 // Then come the virtual base virtual tables, also in inheritance graph 1946 // order, and again excluding primary bases (which share virtual tables with 1947 // the classes for which they are primary). 1948 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), 1949 E = RD->bases_end(); I != E; ++I) { 1950 const CXXRecordDecl *BaseDecl = 1951 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); 1952 1953 // Check if this base needs a vtable. (If it's virtual, not a primary base 1954 // of some other class, and we haven't visited it before). 1955 if (I->isVirtual() && BaseDecl->isDynamicClass() && 1956 !PrimaryVirtualBases.count(BaseDecl) && VBases.insert(BaseDecl)) { 1957 const ASTRecordLayout &MostDerivedClassLayout = 1958 Context.getASTRecordLayout(MostDerivedClass); 1959 CharUnits BaseOffset = 1960 MostDerivedClassLayout.getVBaseClassOffset(BaseDecl); 1961 1962 const ASTRecordLayout &LayoutClassLayout = 1963 Context.getASTRecordLayout(LayoutClass); 1964 CharUnits BaseOffsetInLayoutClass = 1965 LayoutClassLayout.getVBaseClassOffset(BaseDecl); 1966 1967 LayoutPrimaryAndSecondaryVTables( 1968 BaseSubobject(BaseDecl, BaseOffset), 1969 /*BaseIsMorallyVirtual=*/true, 1970 /*BaseIsVirtualInLayoutClass=*/true, 1971 BaseOffsetInLayoutClass); 1972 } 1973 1974 // We only need to check the base for virtual base vtables if it actually 1975 // has virtual bases. 1976 if (BaseDecl->getNumVBases()) 1977 LayoutVTablesForVirtualBases(BaseDecl, VBases); 1978 } 1979} 1980 1981/// dumpLayout - Dump the vtable layout. 1982void VTableBuilder::dumpLayout(llvm::raw_ostream& Out) { 1983 1984 if (isBuildingConstructorVTable()) { 1985 Out << "Construction vtable for ('"; 1986 Out << MostDerivedClass->getQualifiedNameAsString() << "', "; 1987 Out << MostDerivedClassOffset.getQuantity() << ") in '"; 1988 Out << LayoutClass->getQualifiedNameAsString(); 1989 } else { 1990 Out << "Vtable for '"; 1991 Out << MostDerivedClass->getQualifiedNameAsString(); 1992 } 1993 Out << "' (" << Components.size() << " entries).\n"; 1994 1995 // Iterate through the address points and insert them into a new map where 1996 // they are keyed by the index and not the base object. 1997 // Since an address point can be shared by multiple subobjects, we use an 1998 // STL multimap. 1999 std::multimap<uint64_t, BaseSubobject> AddressPointsByIndex; 2000 for (AddressPointsMapTy::const_iterator I = AddressPoints.begin(), 2001 E = AddressPoints.end(); I != E; ++I) { 2002 const BaseSubobject& Base = I->first; 2003 uint64_t Index = I->second; 2004 2005 AddressPointsByIndex.insert(std::make_pair(Index, Base)); 2006 } 2007 2008 for (unsigned I = 0, E = Components.size(); I != E; ++I) { 2009 uint64_t Index = I; 2010 2011 Out << llvm::format("%4d | ", I); 2012 2013 const VTableComponent &Component = Components[I]; 2014 2015 // Dump the component. 2016 switch (Component.getKind()) { 2017 2018 case VTableComponent::CK_VCallOffset: 2019 Out << "vcall_offset (" << Component.getVCallOffset() << ")"; 2020 break; 2021 2022 case VTableComponent::CK_VBaseOffset: 2023 Out << "vbase_offset (" << Component.getVBaseOffset() << ")"; 2024 break; 2025 2026 case VTableComponent::CK_OffsetToTop: 2027 Out << "offset_to_top (" << Component.getOffsetToTop() << ")"; 2028 break; 2029 2030 case VTableComponent::CK_RTTI: 2031 Out << Component.getRTTIDecl()->getQualifiedNameAsString() << " RTTI"; 2032 break; 2033 2034 case VTableComponent::CK_FunctionPointer: { 2035 const CXXMethodDecl *MD = Component.getFunctionDecl(); 2036 2037 std::string Str = 2038 PredefinedExpr::ComputeName(PredefinedExpr::PrettyFunctionNoVirtual, 2039 MD); 2040 Out << Str; 2041 if (MD->isPure()) 2042 Out << " [pure]"; 2043 2044 ThunkInfo Thunk = VTableThunks.lookup(I); 2045 if (!Thunk.isEmpty()) { 2046 // If this function pointer has a return adjustment, dump it. 2047 if (!Thunk.Return.isEmpty()) { 2048 Out << "\n [return adjustment: "; 2049 Out << Thunk.Return.NonVirtual << " non-virtual"; 2050 2051 if (Thunk.Return.VBaseOffsetOffset) { 2052 Out << ", " << Thunk.Return.VBaseOffsetOffset; 2053 Out << " vbase offset offset"; 2054 } 2055 2056 Out << ']'; 2057 } 2058 2059 // If this function pointer has a 'this' pointer adjustment, dump it. 2060 if (!Thunk.This.isEmpty()) { 2061 Out << "\n [this adjustment: "; 2062 Out << Thunk.This.NonVirtual << " non-virtual"; 2063 2064 if (Thunk.This.VCallOffsetOffset) { 2065 Out << ", " << Thunk.This.VCallOffsetOffset; 2066 Out << " vcall offset offset"; 2067 } 2068 2069 Out << ']'; 2070 } 2071 } 2072 2073 break; 2074 } 2075 2076 case VTableComponent::CK_CompleteDtorPointer: 2077 case VTableComponent::CK_DeletingDtorPointer: { 2078 bool IsComplete = 2079 Component.getKind() == VTableComponent::CK_CompleteDtorPointer; 2080 2081 const CXXDestructorDecl *DD = Component.getDestructorDecl(); 2082 2083 Out << DD->getQualifiedNameAsString(); 2084 if (IsComplete) 2085 Out << "() [complete]"; 2086 else 2087 Out << "() [deleting]"; 2088 2089 if (DD->isPure()) 2090 Out << " [pure]"; 2091 2092 ThunkInfo Thunk = VTableThunks.lookup(I); 2093 if (!Thunk.isEmpty()) { 2094 // If this destructor has a 'this' pointer adjustment, dump it. 2095 if (!Thunk.This.isEmpty()) { 2096 Out << "\n [this adjustment: "; 2097 Out << Thunk.This.NonVirtual << " non-virtual"; 2098 2099 if (Thunk.This.VCallOffsetOffset) { 2100 Out << ", " << Thunk.This.VCallOffsetOffset; 2101 Out << " vcall offset offset"; 2102 } 2103 2104 Out << ']'; 2105 } 2106 } 2107 2108 break; 2109 } 2110 2111 case VTableComponent::CK_UnusedFunctionPointer: { 2112 const CXXMethodDecl *MD = Component.getUnusedFunctionDecl(); 2113 2114 std::string Str = 2115 PredefinedExpr::ComputeName(PredefinedExpr::PrettyFunctionNoVirtual, 2116 MD); 2117 Out << "[unused] " << Str; 2118 if (MD->isPure()) 2119 Out << " [pure]"; 2120 } 2121 2122 } 2123 2124 Out << '\n'; 2125 2126 // Dump the next address point. 2127 uint64_t NextIndex = Index + 1; 2128 if (AddressPointsByIndex.count(NextIndex)) { 2129 if (AddressPointsByIndex.count(NextIndex) == 1) { 2130 const BaseSubobject &Base = 2131 AddressPointsByIndex.find(NextIndex)->second; 2132 2133 Out << " -- (" << Base.getBase()->getQualifiedNameAsString(); 2134 Out << ", " << Base.getBaseOffset().getQuantity(); 2135 Out << ") vtable address --\n"; 2136 } else { 2137 CharUnits BaseOffset = 2138 AddressPointsByIndex.lower_bound(NextIndex)->second.getBaseOffset(); 2139 2140 // We store the class names in a set to get a stable order. 2141 std::set<std::string> ClassNames; 2142 for (std::multimap<uint64_t, BaseSubobject>::const_iterator I = 2143 AddressPointsByIndex.lower_bound(NextIndex), E = 2144 AddressPointsByIndex.upper_bound(NextIndex); I != E; ++I) { 2145 assert(I->second.getBaseOffset() == BaseOffset && 2146 "Invalid base offset!"); 2147 const CXXRecordDecl *RD = I->second.getBase(); 2148 ClassNames.insert(RD->getQualifiedNameAsString()); 2149 } 2150 2151 for (std::set<std::string>::const_iterator I = ClassNames.begin(), 2152 E = ClassNames.end(); I != E; ++I) { 2153 Out << " -- (" << *I; 2154 Out << ", " << BaseOffset.getQuantity() << ") vtable address --\n"; 2155 } 2156 } 2157 } 2158 } 2159 2160 Out << '\n'; 2161 2162 if (isBuildingConstructorVTable()) 2163 return; 2164 2165 if (MostDerivedClass->getNumVBases()) { 2166 // We store the virtual base class names and their offsets in a map to get 2167 // a stable order. 2168 2169 std::map<std::string, int64_t> ClassNamesAndOffsets; 2170 for (VBaseOffsetOffsetsMapTy::const_iterator I = VBaseOffsetOffsets.begin(), 2171 E = VBaseOffsetOffsets.end(); I != E; ++I) { 2172 std::string ClassName = I->first->getQualifiedNameAsString(); 2173 int64_t OffsetOffset = I->second; 2174 ClassNamesAndOffsets.insert(std::make_pair(ClassName, OffsetOffset)); 2175 } 2176 2177 Out << "Virtual base offset offsets for '"; 2178 Out << MostDerivedClass->getQualifiedNameAsString() << "' ("; 2179 Out << ClassNamesAndOffsets.size(); 2180 Out << (ClassNamesAndOffsets.size() == 1 ? " entry" : " entries") << ").\n"; 2181 2182 for (std::map<std::string, int64_t>::const_iterator I = 2183 ClassNamesAndOffsets.begin(), E = ClassNamesAndOffsets.end(); 2184 I != E; ++I) 2185 Out << " " << I->first << " | " << I->second << '\n'; 2186 2187 Out << "\n"; 2188 } 2189 2190 if (!Thunks.empty()) { 2191 // We store the method names in a map to get a stable order. 2192 std::map<std::string, const CXXMethodDecl *> MethodNamesAndDecls; 2193 2194 for (ThunksMapTy::const_iterator I = Thunks.begin(), E = Thunks.end(); 2195 I != E; ++I) { 2196 const CXXMethodDecl *MD = I->first; 2197 std::string MethodName = 2198 PredefinedExpr::ComputeName(PredefinedExpr::PrettyFunctionNoVirtual, 2199 MD); 2200 2201 MethodNamesAndDecls.insert(std::make_pair(MethodName, MD)); 2202 } 2203 2204 for (std::map<std::string, const CXXMethodDecl *>::const_iterator I = 2205 MethodNamesAndDecls.begin(), E = MethodNamesAndDecls.end(); 2206 I != E; ++I) { 2207 const std::string &MethodName = I->first; 2208 const CXXMethodDecl *MD = I->second; 2209 2210 ThunkInfoVectorTy ThunksVector = Thunks[MD]; 2211 std::sort(ThunksVector.begin(), ThunksVector.end()); 2212 2213 Out << "Thunks for '" << MethodName << "' (" << ThunksVector.size(); 2214 Out << (ThunksVector.size() == 1 ? " entry" : " entries") << ").\n"; 2215 2216 for (unsigned I = 0, E = ThunksVector.size(); I != E; ++I) { 2217 const ThunkInfo &Thunk = ThunksVector[I]; 2218 2219 Out << llvm::format("%4d | ", I); 2220 2221 // If this function pointer has a return pointer adjustment, dump it. 2222 if (!Thunk.Return.isEmpty()) { 2223 Out << "return adjustment: " << Thunk.This.NonVirtual; 2224 Out << " non-virtual"; 2225 if (Thunk.Return.VBaseOffsetOffset) { 2226 Out << ", " << Thunk.Return.VBaseOffsetOffset; 2227 Out << " vbase offset offset"; 2228 } 2229 2230 if (!Thunk.This.isEmpty()) 2231 Out << "\n "; 2232 } 2233 2234 // If this function pointer has a 'this' pointer adjustment, dump it. 2235 if (!Thunk.This.isEmpty()) { 2236 Out << "this adjustment: "; 2237 Out << Thunk.This.NonVirtual << " non-virtual"; 2238 2239 if (Thunk.This.VCallOffsetOffset) { 2240 Out << ", " << Thunk.This.VCallOffsetOffset; 2241 Out << " vcall offset offset"; 2242 } 2243 } 2244 2245 Out << '\n'; 2246 } 2247 2248 Out << '\n'; 2249 2250 } 2251 } 2252} 2253 2254} 2255 2256static void 2257CollectPrimaryBases(const CXXRecordDecl *RD, ASTContext &Context, 2258 VTableBuilder::PrimaryBasesSetVectorTy &PrimaryBases) { 2259 while (RD) { 2260 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); 2261 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase(); 2262 if (PrimaryBase) 2263 PrimaryBases.insert(PrimaryBase); 2264 2265 RD = PrimaryBase; 2266 } 2267} 2268 2269void CodeGenVTables::ComputeMethodVTableIndices(const CXXRecordDecl *RD) { 2270 2271 // Itanium C++ ABI 2.5.2: 2272 // The order of the virtual function pointers in a virtual table is the 2273 // order of declaration of the corresponding member functions in the class. 2274 // 2275 // There is an entry for any virtual function declared in a class, 2276 // whether it is a new function or overrides a base class function, 2277 // unless it overrides a function from the primary base, and conversion 2278 // between their return types does not require an adjustment. 2279 2280 int64_t CurrentIndex = 0; 2281 2282 const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD); 2283 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase(); 2284 2285 if (PrimaryBase) { 2286 assert(PrimaryBase->isDefinition() && 2287 "Should have the definition decl of the primary base!"); 2288 2289 // Since the record decl shares its vtable pointer with the primary base 2290 // we need to start counting at the end of the primary base's vtable. 2291 CurrentIndex = getNumVirtualFunctionPointers(PrimaryBase); 2292 } 2293 2294 // Collect all the primary bases, so we can check whether methods override 2295 // a method from the base. 2296 VTableBuilder::PrimaryBasesSetVectorTy PrimaryBases; 2297 CollectPrimaryBases(RD, CGM.getContext(), PrimaryBases); 2298 2299 const CXXDestructorDecl *ImplicitVirtualDtor = 0; 2300 2301 for (CXXRecordDecl::method_iterator i = RD->method_begin(), 2302 e = RD->method_end(); i != e; ++i) { 2303 const CXXMethodDecl *MD = *i; 2304 2305 // We only want virtual methods. 2306 if (!MD->isVirtual()) 2307 continue; 2308 2309 // Check if this method overrides a method in the primary base. 2310 if (const CXXMethodDecl *OverriddenMD = 2311 FindNearestOverriddenMethod(MD, PrimaryBases)) { 2312 // Check if converting from the return type of the method to the 2313 // return type of the overridden method requires conversion. 2314 if (ComputeReturnAdjustmentBaseOffset(CGM.getContext(), MD, 2315 OverriddenMD).isEmpty()) { 2316 // This index is shared between the index in the vtable of the primary 2317 // base class. 2318 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) { 2319 const CXXDestructorDecl *OverriddenDD = 2320 cast<CXXDestructorDecl>(OverriddenMD); 2321 2322 // Add both the complete and deleting entries. 2323 MethodVTableIndices[GlobalDecl(DD, Dtor_Complete)] = 2324 getMethodVTableIndex(GlobalDecl(OverriddenDD, Dtor_Complete)); 2325 MethodVTableIndices[GlobalDecl(DD, Dtor_Deleting)] = 2326 getMethodVTableIndex(GlobalDecl(OverriddenDD, Dtor_Deleting)); 2327 } else { 2328 MethodVTableIndices[MD] = getMethodVTableIndex(OverriddenMD); 2329 } 2330 2331 // We don't need to add an entry for this method. 2332 continue; 2333 } 2334 } 2335 2336 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) { 2337 if (MD->isImplicit()) { 2338 assert(!ImplicitVirtualDtor && 2339 "Did already see an implicit virtual dtor!"); 2340 ImplicitVirtualDtor = DD; 2341 continue; 2342 } 2343 2344 // Add the complete dtor. 2345 MethodVTableIndices[GlobalDecl(DD, Dtor_Complete)] = CurrentIndex++; 2346 2347 // Add the deleting dtor. 2348 MethodVTableIndices[GlobalDecl(DD, Dtor_Deleting)] = CurrentIndex++; 2349 } else { 2350 // Add the entry. 2351 MethodVTableIndices[MD] = CurrentIndex++; 2352 } 2353 } 2354 2355 if (ImplicitVirtualDtor) { 2356 // Itanium C++ ABI 2.5.2: 2357 // If a class has an implicitly-defined virtual destructor, 2358 // its entries come after the declared virtual function pointers. 2359 2360 // Add the complete dtor. 2361 MethodVTableIndices[GlobalDecl(ImplicitVirtualDtor, Dtor_Complete)] = 2362 CurrentIndex++; 2363 2364 // Add the deleting dtor. 2365 MethodVTableIndices[GlobalDecl(ImplicitVirtualDtor, Dtor_Deleting)] = 2366 CurrentIndex++; 2367 } 2368 2369 NumVirtualFunctionPointers[RD] = CurrentIndex; 2370} 2371 2372bool CodeGenVTables::ShouldEmitVTableInThisTU(const CXXRecordDecl *RD) { 2373 assert(RD->isDynamicClass() && "Non dynamic classes have no VTable."); 2374 2375 TemplateSpecializationKind TSK = RD->getTemplateSpecializationKind(); 2376 if (TSK == TSK_ExplicitInstantiationDeclaration) 2377 return false; 2378 2379 const CXXMethodDecl *KeyFunction = CGM.getContext().getKeyFunction(RD); 2380 if (!KeyFunction) 2381 return true; 2382 2383 // Itanium C++ ABI, 5.2.6 Instantiated Templates: 2384 // An instantiation of a class template requires: 2385 // - In the object where instantiated, the virtual table... 2386 if (TSK == TSK_ImplicitInstantiation || 2387 TSK == TSK_ExplicitInstantiationDefinition) 2388 return true; 2389 2390 // If we're building with optimization, we always emit VTables since that 2391 // allows for virtual function calls to be devirtualized. 2392 // (We don't want to do this in -fapple-kext mode however). 2393 if (CGM.getCodeGenOpts().OptimizationLevel && !CGM.getLangOptions().AppleKext) 2394 return true; 2395 2396 return KeyFunction->hasBody(); 2397} 2398 2399uint64_t CodeGenVTables::getNumVirtualFunctionPointers(const CXXRecordDecl *RD) { 2400 llvm::DenseMap<const CXXRecordDecl *, uint64_t>::iterator I = 2401 NumVirtualFunctionPointers.find(RD); 2402 if (I != NumVirtualFunctionPointers.end()) 2403 return I->second; 2404 2405 ComputeMethodVTableIndices(RD); 2406 2407 I = NumVirtualFunctionPointers.find(RD); 2408 assert(I != NumVirtualFunctionPointers.end() && "Did not find entry!"); 2409 return I->second; 2410} 2411 2412uint64_t CodeGenVTables::getMethodVTableIndex(GlobalDecl GD) { 2413 MethodVTableIndicesTy::iterator I = MethodVTableIndices.find(GD); 2414 if (I != MethodVTableIndices.end()) 2415 return I->second; 2416 2417 const CXXRecordDecl *RD = cast<CXXMethodDecl>(GD.getDecl())->getParent(); 2418 2419 ComputeMethodVTableIndices(RD); 2420 2421 I = MethodVTableIndices.find(GD); 2422 assert(I != MethodVTableIndices.end() && "Did not find index!"); 2423 return I->second; 2424} 2425 2426int64_t CodeGenVTables::getVirtualBaseOffsetOffset(const CXXRecordDecl *RD, 2427 const CXXRecordDecl *VBase) { 2428 ClassPairTy ClassPair(RD, VBase); 2429 2430 VirtualBaseClassOffsetOffsetsMapTy::iterator I = 2431 VirtualBaseClassOffsetOffsets.find(ClassPair); 2432 if (I != VirtualBaseClassOffsetOffsets.end()) 2433 return I->second; 2434 2435 VCallAndVBaseOffsetBuilder Builder(RD, RD, /*FinalOverriders=*/0, 2436 BaseSubobject(RD, CharUnits::Zero()), 2437 /*BaseIsVirtual=*/false, 2438 /*OffsetInLayoutClass=*/CharUnits::Zero()); 2439 2440 for (VCallAndVBaseOffsetBuilder::VBaseOffsetOffsetsMapTy::const_iterator I = 2441 Builder.getVBaseOffsetOffsets().begin(), 2442 E = Builder.getVBaseOffsetOffsets().end(); I != E; ++I) { 2443 // Insert all types. 2444 ClassPairTy ClassPair(RD, I->first); 2445 2446 VirtualBaseClassOffsetOffsets.insert(std::make_pair(ClassPair, I->second)); 2447 } 2448 2449 I = VirtualBaseClassOffsetOffsets.find(ClassPair); 2450 assert(I != VirtualBaseClassOffsetOffsets.end() && "Did not find index!"); 2451 2452 return I->second; 2453} 2454 2455uint64_t 2456CodeGenVTables::getAddressPoint(BaseSubobject Base, const CXXRecordDecl *RD) { 2457 assert(AddressPoints.count(std::make_pair(RD, Base)) && 2458 "Did not find address point!"); 2459 2460 uint64_t AddressPoint = AddressPoints.lookup(std::make_pair(RD, Base)); 2461 assert(AddressPoint && "Address point must not be zero!"); 2462 2463 return AddressPoint; 2464} 2465 2466llvm::Constant *CodeGenModule::GetAddrOfThunk(GlobalDecl GD, 2467 const ThunkInfo &Thunk) { 2468 const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); 2469 2470 // Compute the mangled name. 2471 llvm::SmallString<256> Name; 2472 llvm::raw_svector_ostream Out(Name); 2473 if (const CXXDestructorDecl* DD = dyn_cast<CXXDestructorDecl>(MD)) 2474 getCXXABI().getMangleContext().mangleCXXDtorThunk(DD, GD.getDtorType(), 2475 Thunk.This, Out); 2476 else 2477 getCXXABI().getMangleContext().mangleThunk(MD, Thunk, Out); 2478 Out.flush(); 2479 2480 const llvm::Type *Ty = getTypes().GetFunctionTypeForVTable(GD); 2481 return GetOrCreateLLVMFunction(Name, Ty, GD, /*ForVTable=*/true); 2482} 2483 2484static llvm::Value *PerformTypeAdjustment(CodeGenFunction &CGF, 2485 llvm::Value *Ptr, 2486 int64_t NonVirtualAdjustment, 2487 int64_t VirtualAdjustment) { 2488 if (!NonVirtualAdjustment && !VirtualAdjustment) 2489 return Ptr; 2490 2491 const llvm::Type *Int8PtrTy = 2492 llvm::Type::getInt8PtrTy(CGF.getLLVMContext()); 2493 2494 llvm::Value *V = CGF.Builder.CreateBitCast(Ptr, Int8PtrTy); 2495 2496 if (NonVirtualAdjustment) { 2497 // Do the non-virtual adjustment. 2498 V = CGF.Builder.CreateConstInBoundsGEP1_64(V, NonVirtualAdjustment); 2499 } 2500 2501 if (VirtualAdjustment) { 2502 const llvm::Type *PtrDiffTy = 2503 CGF.ConvertType(CGF.getContext().getPointerDiffType()); 2504 2505 // Do the virtual adjustment. 2506 llvm::Value *VTablePtrPtr = 2507 CGF.Builder.CreateBitCast(V, Int8PtrTy->getPointerTo()); 2508 2509 llvm::Value *VTablePtr = CGF.Builder.CreateLoad(VTablePtrPtr); 2510 2511 llvm::Value *OffsetPtr = 2512 CGF.Builder.CreateConstInBoundsGEP1_64(VTablePtr, VirtualAdjustment); 2513 2514 OffsetPtr = CGF.Builder.CreateBitCast(OffsetPtr, PtrDiffTy->getPointerTo()); 2515 2516 // Load the adjustment offset from the vtable. 2517 llvm::Value *Offset = CGF.Builder.CreateLoad(OffsetPtr); 2518 2519 // Adjust our pointer. 2520 V = CGF.Builder.CreateInBoundsGEP(V, Offset); 2521 } 2522 2523 // Cast back to the original type. 2524 return CGF.Builder.CreateBitCast(V, Ptr->getType()); 2525} 2526 2527static void setThunkVisibility(CodeGenModule &CGM, const CXXMethodDecl *MD, 2528 const ThunkInfo &Thunk, llvm::Function *Fn) { 2529 CGM.setGlobalVisibility(Fn, MD); 2530 2531 if (!CGM.getCodeGenOpts().HiddenWeakVTables) 2532 return; 2533 2534 // If the thunk has weak/linkonce linkage, but the function must be 2535 // emitted in every translation unit that references it, then we can 2536 // emit its thunks with hidden visibility, since its thunks must be 2537 // emitted when the function is. 2538 2539 // This follows CodeGenModule::setTypeVisibility; see the comments 2540 // there for explanation. 2541 2542 if ((Fn->getLinkage() != llvm::GlobalVariable::LinkOnceODRLinkage && 2543 Fn->getLinkage() != llvm::GlobalVariable::WeakODRLinkage) || 2544 Fn->getVisibility() != llvm::GlobalVariable::DefaultVisibility) 2545 return; 2546 2547 if (MD->getExplicitVisibility()) 2548 return; 2549 2550 switch (MD->getTemplateSpecializationKind()) { 2551 case TSK_ExplicitInstantiationDefinition: 2552 case TSK_ExplicitInstantiationDeclaration: 2553 return; 2554 2555 case TSK_Undeclared: 2556 break; 2557 2558 case TSK_ExplicitSpecialization: 2559 case TSK_ImplicitInstantiation: 2560 if (!CGM.getCodeGenOpts().HiddenWeakTemplateVTables) 2561 return; 2562 break; 2563 } 2564 2565 // If there's an explicit definition, and that definition is 2566 // out-of-line, then we can't assume that all users will have a 2567 // definition to emit. 2568 const FunctionDecl *Def = 0; 2569 if (MD->hasBody(Def) && Def->isOutOfLine()) 2570 return; 2571 2572 Fn->setVisibility(llvm::GlobalValue::HiddenVisibility); 2573} 2574 2575#ifndef NDEBUG 2576static bool similar(const ABIArgInfo &infoL, CanQualType typeL, 2577 const ABIArgInfo &infoR, CanQualType typeR) { 2578 return (infoL.getKind() == infoR.getKind() && 2579 (typeL == typeR || 2580 (isa<PointerType>(typeL) && isa<PointerType>(typeR)) || 2581 (isa<ReferenceType>(typeL) && isa<ReferenceType>(typeR)))); 2582} 2583#endif 2584 2585void CodeGenFunction::GenerateThunk(llvm::Function *Fn, 2586 const CGFunctionInfo &FnInfo, 2587 GlobalDecl GD, const ThunkInfo &Thunk) { 2588 const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); 2589 const FunctionProtoType *FPT = MD->getType()->getAs<FunctionProtoType>(); 2590 QualType ResultType = FPT->getResultType(); 2591 QualType ThisType = MD->getThisType(getContext()); 2592 2593 FunctionArgList FunctionArgs; 2594 2595 // FIXME: It would be nice if more of this code could be shared with 2596 // CodeGenFunction::GenerateCode. 2597 2598 // Create the implicit 'this' parameter declaration. 2599 CurGD = GD; 2600 CGM.getCXXABI().BuildInstanceFunctionParams(*this, ResultType, FunctionArgs); 2601 2602 // Add the rest of the parameters. 2603 for (FunctionDecl::param_const_iterator I = MD->param_begin(), 2604 E = MD->param_end(); I != E; ++I) { 2605 ParmVarDecl *Param = *I; 2606 2607 FunctionArgs.push_back(Param); 2608 } 2609 2610 StartFunction(GlobalDecl(), ResultType, Fn, FnInfo, FunctionArgs, 2611 SourceLocation()); 2612 2613 CGM.getCXXABI().EmitInstanceFunctionProlog(*this); 2614 2615 // Adjust the 'this' pointer if necessary. 2616 llvm::Value *AdjustedThisPtr = 2617 PerformTypeAdjustment(*this, LoadCXXThis(), 2618 Thunk.This.NonVirtual, 2619 Thunk.This.VCallOffsetOffset); 2620 2621 CallArgList CallArgs; 2622 2623 // Add our adjusted 'this' pointer. 2624 CallArgs.push_back(std::make_pair(RValue::get(AdjustedThisPtr), ThisType)); 2625 2626 // Add the rest of the parameters. 2627 for (FunctionDecl::param_const_iterator I = MD->param_begin(), 2628 E = MD->param_end(); I != E; ++I) { 2629 ParmVarDecl *param = *I; 2630 EmitDelegateCallArg(CallArgs, param); 2631 } 2632 2633 // Get our callee. 2634 const llvm::Type *Ty = 2635 CGM.getTypes().GetFunctionType(CGM.getTypes().getFunctionInfo(GD), 2636 FPT->isVariadic()); 2637 llvm::Value *Callee = CGM.GetAddrOfFunction(GD, Ty, /*ForVTable=*/true); 2638 2639#ifndef NDEBUG 2640 const CGFunctionInfo &CallFnInfo = 2641 CGM.getTypes().getFunctionInfo(ResultType, CallArgs, FPT->getExtInfo()); 2642 assert(CallFnInfo.getRegParm() == FnInfo.getRegParm() && 2643 CallFnInfo.isNoReturn() == FnInfo.isNoReturn() && 2644 CallFnInfo.getCallingConvention() == FnInfo.getCallingConvention()); 2645 assert(similar(CallFnInfo.getReturnInfo(), CallFnInfo.getReturnType(), 2646 FnInfo.getReturnInfo(), FnInfo.getReturnType())); 2647 assert(CallFnInfo.arg_size() == FnInfo.arg_size()); 2648 for (unsigned i = 0, e = FnInfo.arg_size(); i != e; ++i) 2649 assert(similar(CallFnInfo.arg_begin()[i].info, 2650 CallFnInfo.arg_begin()[i].type, 2651 FnInfo.arg_begin()[i].info, FnInfo.arg_begin()[i].type)); 2652#endif 2653 2654 // Determine whether we have a return value slot to use. 2655 ReturnValueSlot Slot; 2656 if (!ResultType->isVoidType() && 2657 FnInfo.getReturnInfo().getKind() == ABIArgInfo::Indirect && 2658 hasAggregateLLVMType(CurFnInfo->getReturnType())) 2659 Slot = ReturnValueSlot(ReturnValue, ResultType.isVolatileQualified()); 2660 2661 // Now emit our call. 2662 RValue RV = EmitCall(FnInfo, Callee, Slot, CallArgs, MD); 2663 2664 if (!Thunk.Return.isEmpty()) { 2665 // Emit the return adjustment. 2666 bool NullCheckValue = !ResultType->isReferenceType(); 2667 2668 llvm::BasicBlock *AdjustNull = 0; 2669 llvm::BasicBlock *AdjustNotNull = 0; 2670 llvm::BasicBlock *AdjustEnd = 0; 2671 2672 llvm::Value *ReturnValue = RV.getScalarVal(); 2673 2674 if (NullCheckValue) { 2675 AdjustNull = createBasicBlock("adjust.null"); 2676 AdjustNotNull = createBasicBlock("adjust.notnull"); 2677 AdjustEnd = createBasicBlock("adjust.end"); 2678 2679 llvm::Value *IsNull = Builder.CreateIsNull(ReturnValue); 2680 Builder.CreateCondBr(IsNull, AdjustNull, AdjustNotNull); 2681 EmitBlock(AdjustNotNull); 2682 } 2683 2684 ReturnValue = PerformTypeAdjustment(*this, ReturnValue, 2685 Thunk.Return.NonVirtual, 2686 Thunk.Return.VBaseOffsetOffset); 2687 2688 if (NullCheckValue) { 2689 Builder.CreateBr(AdjustEnd); 2690 EmitBlock(AdjustNull); 2691 Builder.CreateBr(AdjustEnd); 2692 EmitBlock(AdjustEnd); 2693 2694 llvm::PHINode *PHI = Builder.CreatePHI(ReturnValue->getType(), 2); 2695 PHI->addIncoming(ReturnValue, AdjustNotNull); 2696 PHI->addIncoming(llvm::Constant::getNullValue(ReturnValue->getType()), 2697 AdjustNull); 2698 ReturnValue = PHI; 2699 } 2700 2701 RV = RValue::get(ReturnValue); 2702 } 2703 2704 if (!ResultType->isVoidType() && Slot.isNull()) 2705 CGM.getCXXABI().EmitReturnFromThunk(*this, RV, ResultType); 2706 2707 FinishFunction(); 2708 2709 // Set the right linkage. 2710 CGM.setFunctionLinkage(MD, Fn); 2711 2712 // Set the right visibility. 2713 setThunkVisibility(CGM, MD, Thunk, Fn); 2714} 2715 2716void CodeGenVTables::EmitThunk(GlobalDecl GD, const ThunkInfo &Thunk, 2717 bool UseAvailableExternallyLinkage) 2718{ 2719 const CGFunctionInfo &FnInfo = CGM.getTypes().getFunctionInfo(GD); 2720 2721 // FIXME: re-use FnInfo in this computation. 2722 llvm::Constant *Entry = CGM.GetAddrOfThunk(GD, Thunk); 2723 2724 // Strip off a bitcast if we got one back. 2725 if (llvm::ConstantExpr *CE = dyn_cast<llvm::ConstantExpr>(Entry)) { 2726 assert(CE->getOpcode() == llvm::Instruction::BitCast); 2727 Entry = CE->getOperand(0); 2728 } 2729 2730 // There's already a declaration with the same name, check if it has the same 2731 // type or if we need to replace it. 2732 if (cast<llvm::GlobalValue>(Entry)->getType()->getElementType() != 2733 CGM.getTypes().GetFunctionTypeForVTable(GD)) { 2734 llvm::GlobalValue *OldThunkFn = cast<llvm::GlobalValue>(Entry); 2735 2736 // If the types mismatch then we have to rewrite the definition. 2737 assert(OldThunkFn->isDeclaration() && 2738 "Shouldn't replace non-declaration"); 2739 2740 // Remove the name from the old thunk function and get a new thunk. 2741 OldThunkFn->setName(llvm::StringRef()); 2742 Entry = CGM.GetAddrOfThunk(GD, Thunk); 2743 2744 // If needed, replace the old thunk with a bitcast. 2745 if (!OldThunkFn->use_empty()) { 2746 llvm::Constant *NewPtrForOldDecl = 2747 llvm::ConstantExpr::getBitCast(Entry, OldThunkFn->getType()); 2748 OldThunkFn->replaceAllUsesWith(NewPtrForOldDecl); 2749 } 2750 2751 // Remove the old thunk. 2752 OldThunkFn->eraseFromParent(); 2753 } 2754 2755 llvm::Function *ThunkFn = cast<llvm::Function>(Entry); 2756 2757 if (!ThunkFn->isDeclaration()) { 2758 if (UseAvailableExternallyLinkage) { 2759 // There is already a thunk emitted for this function, do nothing. 2760 return; 2761 } 2762 2763 // If a function has a body, it should have available_externally linkage. 2764 assert(ThunkFn->hasAvailableExternallyLinkage() && 2765 "Function should have available_externally linkage!"); 2766 2767 // Change the linkage. 2768 CGM.setFunctionLinkage(cast<CXXMethodDecl>(GD.getDecl()), ThunkFn); 2769 return; 2770 } 2771 2772 // Actually generate the thunk body. 2773 CodeGenFunction(CGM).GenerateThunk(ThunkFn, FnInfo, GD, Thunk); 2774 2775 if (UseAvailableExternallyLinkage) 2776 ThunkFn->setLinkage(llvm::GlobalValue::AvailableExternallyLinkage); 2777} 2778 2779void CodeGenVTables::MaybeEmitThunkAvailableExternally(GlobalDecl GD, 2780 const ThunkInfo &Thunk) { 2781 // We only want to do this when building with optimizations. 2782 if (!CGM.getCodeGenOpts().OptimizationLevel) 2783 return; 2784 2785 // We can't emit thunks for member functions with incomplete types. 2786 const CXXMethodDecl *MD = cast<CXXMethodDecl>(GD.getDecl()); 2787 if (CGM.getTypes().VerifyFuncTypeComplete(MD->getType().getTypePtr())) 2788 return; 2789 2790 EmitThunk(GD, Thunk, /*UseAvailableExternallyLinkage=*/true); 2791} 2792 2793void CodeGenVTables::EmitThunks(GlobalDecl GD) 2794{ 2795 const CXXMethodDecl *MD = 2796 cast<CXXMethodDecl>(GD.getDecl())->getCanonicalDecl(); 2797 2798 // We don't need to generate thunks for the base destructor. 2799 if (isa<CXXDestructorDecl>(MD) && GD.getDtorType() == Dtor_Base) 2800 return; 2801 2802 const CXXRecordDecl *RD = MD->getParent(); 2803 2804 // Compute VTable related info for this class. 2805 ComputeVTableRelatedInformation(RD, false); 2806 2807 ThunksMapTy::const_iterator I = Thunks.find(MD); 2808 if (I == Thunks.end()) { 2809 // We did not find a thunk for this method. 2810 return; 2811 } 2812 2813 const ThunkInfoVectorTy &ThunkInfoVector = I->second; 2814 for (unsigned I = 0, E = ThunkInfoVector.size(); I != E; ++I) 2815 EmitThunk(GD, ThunkInfoVector[I], /*UseAvailableExternallyLinkage=*/false); 2816} 2817 2818void CodeGenVTables::ComputeVTableRelatedInformation(const CXXRecordDecl *RD, 2819 bool RequireVTable) { 2820 VTableLayoutData &Entry = VTableLayoutMap[RD]; 2821 2822 // We may need to generate a definition for this vtable. 2823 if (RequireVTable && !Entry.getInt()) { 2824 if (ShouldEmitVTableInThisTU(RD)) 2825 CGM.DeferredVTables.push_back(RD); 2826 2827 Entry.setInt(true); 2828 } 2829 2830 // Check if we've computed this information before. 2831 if (Entry.getPointer()) 2832 return; 2833 2834 VTableBuilder Builder(*this, RD, CharUnits::Zero(), 2835 /*MostDerivedClassIsVirtual=*/0, RD); 2836 2837 // Add the VTable layout. 2838 uint64_t NumVTableComponents = Builder.getNumVTableComponents(); 2839 // -fapple-kext adds an extra entry at end of vtbl. 2840 bool IsAppleKext = CGM.getContext().getLangOptions().AppleKext; 2841 if (IsAppleKext) 2842 NumVTableComponents += 1; 2843 2844 uint64_t *LayoutData = new uint64_t[NumVTableComponents + 1]; 2845 if (IsAppleKext) 2846 LayoutData[NumVTableComponents] = 0; 2847 Entry.setPointer(LayoutData); 2848 2849 // Store the number of components. 2850 LayoutData[0] = NumVTableComponents; 2851 2852 // Store the components. 2853 std::copy(Builder.vtable_components_data_begin(), 2854 Builder.vtable_components_data_end(), 2855 &LayoutData[1]); 2856 2857 // Add the known thunks. 2858 Thunks.insert(Builder.thunks_begin(), Builder.thunks_end()); 2859 2860 // Add the thunks needed in this vtable. 2861 assert(!VTableThunksMap.count(RD) && 2862 "Thunks already exists for this vtable!"); 2863 2864 VTableThunksTy &VTableThunks = VTableThunksMap[RD]; 2865 VTableThunks.append(Builder.vtable_thunks_begin(), 2866 Builder.vtable_thunks_end()); 2867 2868 // Sort them. 2869 std::sort(VTableThunks.begin(), VTableThunks.end()); 2870 2871 // Add the address points. 2872 for (VTableBuilder::AddressPointsMapTy::const_iterator I = 2873 Builder.address_points_begin(), E = Builder.address_points_end(); 2874 I != E; ++I) { 2875 2876 uint64_t &AddressPoint = AddressPoints[std::make_pair(RD, I->first)]; 2877 2878 // Check if we already have the address points for this base. 2879 assert(!AddressPoint && "Address point already exists for this base!"); 2880 2881 AddressPoint = I->second; 2882 } 2883 2884 // If we don't have the vbase information for this class, insert it. 2885 // getVirtualBaseOffsetOffset will compute it separately without computing 2886 // the rest of the vtable related information. 2887 if (!RD->getNumVBases()) 2888 return; 2889 2890 const RecordType *VBaseRT = 2891 RD->vbases_begin()->getType()->getAs<RecordType>(); 2892 const CXXRecordDecl *VBase = cast<CXXRecordDecl>(VBaseRT->getDecl()); 2893 2894 if (VirtualBaseClassOffsetOffsets.count(std::make_pair(RD, VBase))) 2895 return; 2896 2897 for (VTableBuilder::VBaseOffsetOffsetsMapTy::const_iterator I = 2898 Builder.getVBaseOffsetOffsets().begin(), 2899 E = Builder.getVBaseOffsetOffsets().end(); I != E; ++I) { 2900 // Insert all types. 2901 ClassPairTy ClassPair(RD, I->first); 2902 2903 VirtualBaseClassOffsetOffsets.insert(std::make_pair(ClassPair, I->second)); 2904 } 2905} 2906 2907llvm::Constant * 2908CodeGenVTables::CreateVTableInitializer(const CXXRecordDecl *RD, 2909 const uint64_t *Components, 2910 unsigned NumComponents, 2911 const VTableThunksTy &VTableThunks) { 2912 llvm::SmallVector<llvm::Constant *, 64> Inits; 2913 2914 const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGM.getLLVMContext()); 2915 2916 const llvm::Type *PtrDiffTy = 2917 CGM.getTypes().ConvertType(CGM.getContext().getPointerDiffType()); 2918 2919 QualType ClassType = CGM.getContext().getTagDeclType(RD); 2920 llvm::Constant *RTTI = CGM.GetAddrOfRTTIDescriptor(ClassType); 2921 2922 unsigned NextVTableThunkIndex = 0; 2923 2924 llvm::Constant* PureVirtualFn = 0; 2925 2926 for (unsigned I = 0; I != NumComponents; ++I) { 2927 VTableComponent Component = 2928 VTableComponent::getFromOpaqueInteger(Components[I]); 2929 2930 llvm::Constant *Init = 0; 2931 2932 switch (Component.getKind()) { 2933 case VTableComponent::CK_VCallOffset: 2934 Init = llvm::ConstantInt::get(PtrDiffTy, Component.getVCallOffset()); 2935 Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy); 2936 break; 2937 case VTableComponent::CK_VBaseOffset: 2938 Init = llvm::ConstantInt::get(PtrDiffTy, Component.getVBaseOffset()); 2939 Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy); 2940 break; 2941 case VTableComponent::CK_OffsetToTop: 2942 Init = llvm::ConstantInt::get(PtrDiffTy, Component.getOffsetToTop()); 2943 Init = llvm::ConstantExpr::getIntToPtr(Init, Int8PtrTy); 2944 break; 2945 case VTableComponent::CK_RTTI: 2946 Init = llvm::ConstantExpr::getBitCast(RTTI, Int8PtrTy); 2947 break; 2948 case VTableComponent::CK_FunctionPointer: 2949 case VTableComponent::CK_CompleteDtorPointer: 2950 case VTableComponent::CK_DeletingDtorPointer: { 2951 GlobalDecl GD; 2952 2953 // Get the right global decl. 2954 switch (Component.getKind()) { 2955 default: 2956 llvm_unreachable("Unexpected vtable component kind"); 2957 case VTableComponent::CK_FunctionPointer: 2958 GD = Component.getFunctionDecl(); 2959 break; 2960 case VTableComponent::CK_CompleteDtorPointer: 2961 GD = GlobalDecl(Component.getDestructorDecl(), Dtor_Complete); 2962 break; 2963 case VTableComponent::CK_DeletingDtorPointer: 2964 GD = GlobalDecl(Component.getDestructorDecl(), Dtor_Deleting); 2965 break; 2966 } 2967 2968 if (cast<CXXMethodDecl>(GD.getDecl())->isPure()) { 2969 // We have a pure virtual member function. 2970 if (!PureVirtualFn) { 2971 const llvm::FunctionType *Ty = 2972 llvm::FunctionType::get(llvm::Type::getVoidTy(CGM.getLLVMContext()), 2973 /*isVarArg=*/false); 2974 PureVirtualFn = 2975 CGM.CreateRuntimeFunction(Ty, "__cxa_pure_virtual"); 2976 PureVirtualFn = llvm::ConstantExpr::getBitCast(PureVirtualFn, 2977 Int8PtrTy); 2978 } 2979 2980 Init = PureVirtualFn; 2981 } else { 2982 // Check if we should use a thunk. 2983 if (NextVTableThunkIndex < VTableThunks.size() && 2984 VTableThunks[NextVTableThunkIndex].first == I) { 2985 const ThunkInfo &Thunk = VTableThunks[NextVTableThunkIndex].second; 2986 2987 Init = CGM.GetAddrOfThunk(GD, Thunk); 2988 MaybeEmitThunkAvailableExternally(GD, Thunk); 2989 2990 NextVTableThunkIndex++; 2991 } else { 2992 const llvm::Type *Ty = CGM.getTypes().GetFunctionTypeForVTable(GD); 2993 2994 Init = CGM.GetAddrOfFunction(GD, Ty, /*ForVTable=*/true); 2995 } 2996 2997 Init = llvm::ConstantExpr::getBitCast(Init, Int8PtrTy); 2998 } 2999 break; 3000 } 3001 3002 case VTableComponent::CK_UnusedFunctionPointer: 3003 Init = llvm::ConstantExpr::getNullValue(Int8PtrTy); 3004 break; 3005 }; 3006 3007 Inits.push_back(Init); 3008 } 3009 3010 llvm::ArrayType *ArrayType = llvm::ArrayType::get(Int8PtrTy, NumComponents); 3011 return llvm::ConstantArray::get(ArrayType, Inits.data(), Inits.size()); 3012} 3013 3014llvm::GlobalVariable *CodeGenVTables::GetAddrOfVTable(const CXXRecordDecl *RD) { 3015 llvm::SmallString<256> OutName; 3016 llvm::raw_svector_ostream Out(OutName); 3017 CGM.getCXXABI().getMangleContext().mangleCXXVTable(RD, Out); 3018 Out.flush(); 3019 llvm::StringRef Name = OutName.str(); 3020 3021 ComputeVTableRelatedInformation(RD, true); 3022 3023 const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGM.getLLVMContext()); 3024 llvm::ArrayType *ArrayType = 3025 llvm::ArrayType::get(Int8PtrTy, getNumVTableComponents(RD)); 3026 3027 llvm::GlobalVariable *GV = 3028 CGM.CreateOrReplaceCXXRuntimeVariable(Name, ArrayType, 3029 llvm::GlobalValue::ExternalLinkage); 3030 GV->setUnnamedAddr(true); 3031 return GV; 3032} 3033 3034void 3035CodeGenVTables::EmitVTableDefinition(llvm::GlobalVariable *VTable, 3036 llvm::GlobalVariable::LinkageTypes Linkage, 3037 const CXXRecordDecl *RD) { 3038 // Dump the vtable layout if necessary. 3039 if (CGM.getLangOptions().DumpVTableLayouts) { 3040 VTableBuilder Builder(*this, RD, CharUnits::Zero(), 3041 /*MostDerivedClassIsVirtual=*/0, RD); 3042 3043 Builder.dumpLayout(llvm::errs()); 3044 } 3045 3046 assert(VTableThunksMap.count(RD) && 3047 "No thunk status for this record decl!"); 3048 3049 const VTableThunksTy& Thunks = VTableThunksMap[RD]; 3050 3051 // Create and set the initializer. 3052 llvm::Constant *Init = 3053 CreateVTableInitializer(RD, getVTableComponentsData(RD), 3054 getNumVTableComponents(RD), Thunks); 3055 VTable->setInitializer(Init); 3056 3057 // Set the correct linkage. 3058 VTable->setLinkage(Linkage); 3059 3060 // Set the right visibility. 3061 CGM.setTypeVisibility(VTable, RD, CodeGenModule::TVK_ForVTable); 3062} 3063 3064llvm::GlobalVariable * 3065CodeGenVTables::GenerateConstructionVTable(const CXXRecordDecl *RD, 3066 const BaseSubobject &Base, 3067 bool BaseIsVirtual, 3068 llvm::GlobalVariable::LinkageTypes Linkage, 3069 VTableAddressPointsMapTy& AddressPoints) { 3070 VTableBuilder Builder(*this, Base.getBase(), 3071 Base.getBaseOffset(), 3072 /*MostDerivedClassIsVirtual=*/BaseIsVirtual, RD); 3073 3074 // Dump the vtable layout if necessary. 3075 if (CGM.getLangOptions().DumpVTableLayouts) 3076 Builder.dumpLayout(llvm::errs()); 3077 3078 // Add the address points. 3079 AddressPoints.insert(Builder.address_points_begin(), 3080 Builder.address_points_end()); 3081 3082 // Get the mangled construction vtable name. 3083 llvm::SmallString<256> OutName; 3084 llvm::raw_svector_ostream Out(OutName); 3085 CGM.getCXXABI().getMangleContext(). 3086 mangleCXXCtorVTable(RD, Base.getBaseOffset().getQuantity(), Base.getBase(), 3087 Out); 3088 Out.flush(); 3089 llvm::StringRef Name = OutName.str(); 3090 3091 const llvm::Type *Int8PtrTy = llvm::Type::getInt8PtrTy(CGM.getLLVMContext()); 3092 llvm::ArrayType *ArrayType = 3093 llvm::ArrayType::get(Int8PtrTy, Builder.getNumVTableComponents()); 3094 3095 // Create the variable that will hold the construction vtable. 3096 llvm::GlobalVariable *VTable = 3097 CGM.CreateOrReplaceCXXRuntimeVariable(Name, ArrayType, Linkage); 3098 CGM.setTypeVisibility(VTable, RD, CodeGenModule::TVK_ForConstructionVTable); 3099 3100 // V-tables are always unnamed_addr. 3101 VTable->setUnnamedAddr(true); 3102 3103 // Add the thunks. 3104 VTableThunksTy VTableThunks; 3105 VTableThunks.append(Builder.vtable_thunks_begin(), 3106 Builder.vtable_thunks_end()); 3107 3108 // Sort them. 3109 std::sort(VTableThunks.begin(), VTableThunks.end()); 3110 3111 // Create and set the initializer. 3112 llvm::Constant *Init = 3113 CreateVTableInitializer(Base.getBase(), 3114 Builder.vtable_components_data_begin(), 3115 Builder.getNumVTableComponents(), VTableThunks); 3116 VTable->setInitializer(Init); 3117 3118 return VTable; 3119} 3120 3121void 3122CodeGenVTables::GenerateClassData(llvm::GlobalVariable::LinkageTypes Linkage, 3123 const CXXRecordDecl *RD) { 3124 llvm::GlobalVariable *&VTable = VTables[RD]; 3125 if (VTable) { 3126 assert(VTable->getInitializer() && "VTable doesn't have a definition!"); 3127 return; 3128 } 3129 3130 VTable = GetAddrOfVTable(RD); 3131 EmitVTableDefinition(VTable, Linkage, RD); 3132 3133 if (RD->getNumVBases()) { 3134 llvm::GlobalVariable *VTT = GetAddrOfVTT(RD); 3135 EmitVTTDefinition(VTT, Linkage, RD); 3136 } 3137 3138 // If this is the magic class __cxxabiv1::__fundamental_type_info, 3139 // we will emit the typeinfo for the fundamental types. This is the 3140 // same behaviour as GCC. 3141 const DeclContext *DC = RD->getDeclContext(); 3142 if (RD->getIdentifier() && 3143 RD->getIdentifier()->isStr("__fundamental_type_info") && 3144 isa<NamespaceDecl>(DC) && 3145 cast<NamespaceDecl>(DC)->getIdentifier() && 3146 cast<NamespaceDecl>(DC)->getIdentifier()->isStr("__cxxabiv1") && 3147 DC->getParent()->isTranslationUnit()) 3148 CGM.EmitFundamentalRTTIDescriptors(); 3149} 3150