clang  7.0.0svn
VTableBuilder.cpp
Go to the documentation of this file.
1 //===--- VTableBuilder.cpp - C++ vtable layout builder --------------------===//
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 generation of the layout of virtual tables.
11 //
12 //===----------------------------------------------------------------------===//
13 
15 #include "clang/AST/ASTContext.h"
18 #include "clang/AST/RecordLayout.h"
19 #include "clang/Basic/TargetInfo.h"
20 #include "llvm/ADT/SetOperations.h"
21 #include "llvm/ADT/SmallPtrSet.h"
22 #include "llvm/Support/Format.h"
23 #include "llvm/Support/raw_ostream.h"
24 #include <algorithm>
25 #include <cstdio>
26 
27 using namespace clang;
28 
29 #define DUMP_OVERRIDERS 0
30 
31 namespace {
32 
33 /// BaseOffset - Represents an offset from a derived class to a direct or
34 /// indirect base class.
35 struct BaseOffset {
36  /// DerivedClass - The derived class.
37  const CXXRecordDecl *DerivedClass;
38 
39  /// VirtualBase - If the path from the derived class to the base class
40  /// involves virtual base classes, this holds the declaration of the last
41  /// virtual base in this path (i.e. closest to the base class).
42  const CXXRecordDecl *VirtualBase;
43 
44  /// NonVirtualOffset - The offset from the derived class to the base class.
45  /// (Or the offset from the virtual base class to the base class, if the
46  /// path from the derived class to the base class involves a virtual base
47  /// class.
48  CharUnits NonVirtualOffset;
49 
50  BaseOffset() : DerivedClass(nullptr), VirtualBase(nullptr),
51  NonVirtualOffset(CharUnits::Zero()) { }
52  BaseOffset(const CXXRecordDecl *DerivedClass,
53  const CXXRecordDecl *VirtualBase, CharUnits NonVirtualOffset)
54  : DerivedClass(DerivedClass), VirtualBase(VirtualBase),
55  NonVirtualOffset(NonVirtualOffset) { }
56 
57  bool isEmpty() const { return NonVirtualOffset.isZero() && !VirtualBase; }
58 };
59 
60 /// FinalOverriders - Contains the final overrider member functions for all
61 /// member functions in the base subobjects of a class.
62 class FinalOverriders {
63 public:
64  /// OverriderInfo - Information about a final overrider.
65  struct OverriderInfo {
66  /// Method - The method decl of the overrider.
67  const CXXMethodDecl *Method;
68 
69  /// VirtualBase - The virtual base class subobject of this overrider.
70  /// Note that this records the closest derived virtual base class subobject.
71  const CXXRecordDecl *VirtualBase;
72 
73  /// Offset - the base offset of the overrider's parent in the layout class.
75 
76  OverriderInfo() : Method(nullptr), VirtualBase(nullptr),
77  Offset(CharUnits::Zero()) { }
78  };
79 
80 private:
81  /// MostDerivedClass - The most derived class for which the final overriders
82  /// are stored.
83  const CXXRecordDecl *MostDerivedClass;
84 
85  /// MostDerivedClassOffset - If we're building final overriders for a
86  /// construction vtable, this holds the offset from the layout class to the
87  /// most derived class.
88  const CharUnits MostDerivedClassOffset;
89 
90  /// LayoutClass - The class we're using for layout information. Will be
91  /// different than the most derived class if the final overriders are for a
92  /// construction vtable.
93  const CXXRecordDecl *LayoutClass;
94 
95  ASTContext &Context;
96 
97  /// MostDerivedClassLayout - the AST record layout of the most derived class.
98  const ASTRecordLayout &MostDerivedClassLayout;
99 
100  /// MethodBaseOffsetPairTy - Uniquely identifies a member function
101  /// in a base subobject.
102  typedef std::pair<const CXXMethodDecl *, CharUnits> MethodBaseOffsetPairTy;
103 
104  typedef llvm::DenseMap<MethodBaseOffsetPairTy,
105  OverriderInfo> OverridersMapTy;
106 
107  /// OverridersMap - The final overriders for all virtual member functions of
108  /// all the base subobjects of the most derived class.
109  OverridersMapTy OverridersMap;
110 
111  /// SubobjectsToOffsetsMapTy - A mapping from a base subobject (represented
112  /// as a record decl and a subobject number) and its offsets in the most
113  /// derived class as well as the layout class.
114  typedef llvm::DenseMap<std::pair<const CXXRecordDecl *, unsigned>,
115  CharUnits> SubobjectOffsetMapTy;
116 
117  typedef llvm::DenseMap<const CXXRecordDecl *, unsigned> SubobjectCountMapTy;
118 
119  /// ComputeBaseOffsets - Compute the offsets for all base subobjects of the
120  /// given base.
121  void ComputeBaseOffsets(BaseSubobject Base, bool IsVirtual,
122  CharUnits OffsetInLayoutClass,
123  SubobjectOffsetMapTy &SubobjectOffsets,
124  SubobjectOffsetMapTy &SubobjectLayoutClassOffsets,
125  SubobjectCountMapTy &SubobjectCounts);
126 
127  typedef llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBasesSetTy;
128 
129  /// dump - dump the final overriders for a base subobject, and all its direct
130  /// and indirect base subobjects.
131  void dump(raw_ostream &Out, BaseSubobject Base,
132  VisitedVirtualBasesSetTy& VisitedVirtualBases);
133 
134 public:
135  FinalOverriders(const CXXRecordDecl *MostDerivedClass,
136  CharUnits MostDerivedClassOffset,
137  const CXXRecordDecl *LayoutClass);
138 
139  /// getOverrider - Get the final overrider for the given method declaration in
140  /// the subobject with the given base offset.
141  OverriderInfo getOverrider(const CXXMethodDecl *MD,
142  CharUnits BaseOffset) const {
143  assert(OverridersMap.count(std::make_pair(MD, BaseOffset)) &&
144  "Did not find overrider!");
145 
146  return OverridersMap.lookup(std::make_pair(MD, BaseOffset));
147  }
148 
149  /// dump - dump the final overriders.
150  void dump() {
151  VisitedVirtualBasesSetTy VisitedVirtualBases;
152  dump(llvm::errs(), BaseSubobject(MostDerivedClass, CharUnits::Zero()),
153  VisitedVirtualBases);
154  }
155 
156 };
157 
158 FinalOverriders::FinalOverriders(const CXXRecordDecl *MostDerivedClass,
159  CharUnits MostDerivedClassOffset,
160  const CXXRecordDecl *LayoutClass)
161  : MostDerivedClass(MostDerivedClass),
162  MostDerivedClassOffset(MostDerivedClassOffset), LayoutClass(LayoutClass),
163  Context(MostDerivedClass->getASTContext()),
164  MostDerivedClassLayout(Context.getASTRecordLayout(MostDerivedClass)) {
165 
166  // Compute base offsets.
167  SubobjectOffsetMapTy SubobjectOffsets;
168  SubobjectOffsetMapTy SubobjectLayoutClassOffsets;
169  SubobjectCountMapTy SubobjectCounts;
170  ComputeBaseOffsets(BaseSubobject(MostDerivedClass, CharUnits::Zero()),
171  /*IsVirtual=*/false,
172  MostDerivedClassOffset,
173  SubobjectOffsets, SubobjectLayoutClassOffsets,
174  SubobjectCounts);
175 
176  // Get the final overriders.
177  CXXFinalOverriderMap FinalOverriders;
178  MostDerivedClass->getFinalOverriders(FinalOverriders);
179 
180  for (const auto &Overrider : FinalOverriders) {
181  const CXXMethodDecl *MD = Overrider.first;
182  const OverridingMethods &Methods = Overrider.second;
183 
184  for (const auto &M : Methods) {
185  unsigned SubobjectNumber = M.first;
186  assert(SubobjectOffsets.count(std::make_pair(MD->getParent(),
187  SubobjectNumber)) &&
188  "Did not find subobject offset!");
189 
190  CharUnits BaseOffset = SubobjectOffsets[std::make_pair(MD->getParent(),
191  SubobjectNumber)];
192 
193  assert(M.second.size() == 1 && "Final overrider is not unique!");
194  const UniqueVirtualMethod &Method = M.second.front();
195 
196  const CXXRecordDecl *OverriderRD = Method.Method->getParent();
197  assert(SubobjectLayoutClassOffsets.count(
198  std::make_pair(OverriderRD, Method.Subobject))
199  && "Did not find subobject offset!");
200  CharUnits OverriderOffset =
201  SubobjectLayoutClassOffsets[std::make_pair(OverriderRD,
202  Method.Subobject)];
203 
204  OverriderInfo& Overrider = OverridersMap[std::make_pair(MD, BaseOffset)];
205  assert(!Overrider.Method && "Overrider should not exist yet!");
206 
207  Overrider.Offset = OverriderOffset;
208  Overrider.Method = Method.Method;
209  Overrider.VirtualBase = Method.InVirtualSubobject;
210  }
211  }
212 
213 #if DUMP_OVERRIDERS
214  // And dump them (for now).
215  dump();
216 #endif
217 }
218 
219 static BaseOffset ComputeBaseOffset(const ASTContext &Context,
220  const CXXRecordDecl *DerivedRD,
221  const CXXBasePath &Path) {
222  CharUnits NonVirtualOffset = CharUnits::Zero();
223 
224  unsigned NonVirtualStart = 0;
225  const CXXRecordDecl *VirtualBase = nullptr;
226 
227  // First, look for the virtual base class.
228  for (int I = Path.size(), E = 0; I != E; --I) {
229  const CXXBasePathElement &Element = Path[I - 1];
230 
231  if (Element.Base->isVirtual()) {
232  NonVirtualStart = I;
233  QualType VBaseType = Element.Base->getType();
234  VirtualBase = VBaseType->getAsCXXRecordDecl();
235  break;
236  }
237  }
238 
239  // Now compute the non-virtual offset.
240  for (unsigned I = NonVirtualStart, E = Path.size(); I != E; ++I) {
241  const CXXBasePathElement &Element = Path[I];
242 
243  // Check the base class offset.
244  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Element.Class);
245 
246  const CXXRecordDecl *Base = Element.Base->getType()->getAsCXXRecordDecl();
247 
248  NonVirtualOffset += Layout.getBaseClassOffset(Base);
249  }
250 
251  // FIXME: This should probably use CharUnits or something. Maybe we should
252  // even change the base offsets in ASTRecordLayout to be specified in
253  // CharUnits.
254  return BaseOffset(DerivedRD, VirtualBase, NonVirtualOffset);
255 
256 }
257 
258 static BaseOffset ComputeBaseOffset(const ASTContext &Context,
259  const CXXRecordDecl *BaseRD,
260  const CXXRecordDecl *DerivedRD) {
261  CXXBasePaths Paths(/*FindAmbiguities=*/false,
262  /*RecordPaths=*/true, /*DetectVirtual=*/false);
263 
264  if (!DerivedRD->isDerivedFrom(BaseRD, Paths))
265  llvm_unreachable("Class must be derived from the passed in base class!");
266 
267  return ComputeBaseOffset(Context, DerivedRD, Paths.front());
268 }
269 
270 static BaseOffset
271 ComputeReturnAdjustmentBaseOffset(ASTContext &Context,
272  const CXXMethodDecl *DerivedMD,
273  const CXXMethodDecl *BaseMD) {
274  const FunctionType *BaseFT = BaseMD->getType()->getAs<FunctionType>();
275  const FunctionType *DerivedFT = DerivedMD->getType()->getAs<FunctionType>();
276 
277  // Canonicalize the return types.
278  CanQualType CanDerivedReturnType =
279  Context.getCanonicalType(DerivedFT->getReturnType());
280  CanQualType CanBaseReturnType =
281  Context.getCanonicalType(BaseFT->getReturnType());
282 
283  assert(CanDerivedReturnType->getTypeClass() ==
284  CanBaseReturnType->getTypeClass() &&
285  "Types must have same type class!");
286 
287  if (CanDerivedReturnType == CanBaseReturnType) {
288  // No adjustment needed.
289  return BaseOffset();
290  }
291 
292  if (isa<ReferenceType>(CanDerivedReturnType)) {
293  CanDerivedReturnType =
294  CanDerivedReturnType->getAs<ReferenceType>()->getPointeeType();
295  CanBaseReturnType =
296  CanBaseReturnType->getAs<ReferenceType>()->getPointeeType();
297  } else if (isa<PointerType>(CanDerivedReturnType)) {
298  CanDerivedReturnType =
299  CanDerivedReturnType->getAs<PointerType>()->getPointeeType();
300  CanBaseReturnType =
301  CanBaseReturnType->getAs<PointerType>()->getPointeeType();
302  } else {
303  llvm_unreachable("Unexpected return type!");
304  }
305 
306  // We need to compare unqualified types here; consider
307  // const T *Base::foo();
308  // T *Derived::foo();
309  if (CanDerivedReturnType.getUnqualifiedType() ==
310  CanBaseReturnType.getUnqualifiedType()) {
311  // No adjustment needed.
312  return BaseOffset();
313  }
314 
315  const CXXRecordDecl *DerivedRD =
316  cast<CXXRecordDecl>(cast<RecordType>(CanDerivedReturnType)->getDecl());
317 
318  const CXXRecordDecl *BaseRD =
319  cast<CXXRecordDecl>(cast<RecordType>(CanBaseReturnType)->getDecl());
320 
321  return ComputeBaseOffset(Context, BaseRD, DerivedRD);
322 }
323 
324 void
325 FinalOverriders::ComputeBaseOffsets(BaseSubobject Base, bool IsVirtual,
326  CharUnits OffsetInLayoutClass,
327  SubobjectOffsetMapTy &SubobjectOffsets,
328  SubobjectOffsetMapTy &SubobjectLayoutClassOffsets,
329  SubobjectCountMapTy &SubobjectCounts) {
330  const CXXRecordDecl *RD = Base.getBase();
331 
332  unsigned SubobjectNumber = 0;
333  if (!IsVirtual)
334  SubobjectNumber = ++SubobjectCounts[RD];
335 
336  // Set up the subobject to offset mapping.
337  assert(!SubobjectOffsets.count(std::make_pair(RD, SubobjectNumber))
338  && "Subobject offset already exists!");
339  assert(!SubobjectLayoutClassOffsets.count(std::make_pair(RD, SubobjectNumber))
340  && "Subobject offset already exists!");
341 
342  SubobjectOffsets[std::make_pair(RD, SubobjectNumber)] = Base.getBaseOffset();
343  SubobjectLayoutClassOffsets[std::make_pair(RD, SubobjectNumber)] =
344  OffsetInLayoutClass;
345 
346  // Traverse our bases.
347  for (const auto &B : RD->bases()) {
348  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
349 
350  CharUnits BaseOffset;
351  CharUnits BaseOffsetInLayoutClass;
352  if (B.isVirtual()) {
353  // Check if we've visited this virtual base before.
354  if (SubobjectOffsets.count(std::make_pair(BaseDecl, 0)))
355  continue;
356 
357  const ASTRecordLayout &LayoutClassLayout =
358  Context.getASTRecordLayout(LayoutClass);
359 
360  BaseOffset = MostDerivedClassLayout.getVBaseClassOffset(BaseDecl);
361  BaseOffsetInLayoutClass =
362  LayoutClassLayout.getVBaseClassOffset(BaseDecl);
363  } else {
364  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
365  CharUnits Offset = Layout.getBaseClassOffset(BaseDecl);
366 
367  BaseOffset = Base.getBaseOffset() + Offset;
368  BaseOffsetInLayoutClass = OffsetInLayoutClass + Offset;
369  }
370 
371  ComputeBaseOffsets(BaseSubobject(BaseDecl, BaseOffset),
372  B.isVirtual(), BaseOffsetInLayoutClass,
373  SubobjectOffsets, SubobjectLayoutClassOffsets,
374  SubobjectCounts);
375  }
376 }
377 
378 void FinalOverriders::dump(raw_ostream &Out, BaseSubobject Base,
379  VisitedVirtualBasesSetTy &VisitedVirtualBases) {
380  const CXXRecordDecl *RD = Base.getBase();
381  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
382 
383  for (const auto &B : RD->bases()) {
384  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
385 
386  // Ignore bases that don't have any virtual member functions.
387  if (!BaseDecl->isPolymorphic())
388  continue;
389 
390  CharUnits BaseOffset;
391  if (B.isVirtual()) {
392  if (!VisitedVirtualBases.insert(BaseDecl).second) {
393  // We've visited this base before.
394  continue;
395  }
396 
397  BaseOffset = MostDerivedClassLayout.getVBaseClassOffset(BaseDecl);
398  } else {
399  BaseOffset = Layout.getBaseClassOffset(BaseDecl) + Base.getBaseOffset();
400  }
401 
402  dump(Out, BaseSubobject(BaseDecl, BaseOffset), VisitedVirtualBases);
403  }
404 
405  Out << "Final overriders for (";
406  RD->printQualifiedName(Out);
407  Out << ", ";
408  Out << Base.getBaseOffset().getQuantity() << ")\n";
409 
410  // Now dump the overriders for this base subobject.
411  for (const auto *MD : RD->methods()) {
412  if (!MD->isVirtual())
413  continue;
414  MD = MD->getCanonicalDecl();
415 
416  OverriderInfo Overrider = getOverrider(MD, Base.getBaseOffset());
417 
418  Out << " ";
419  MD->printQualifiedName(Out);
420  Out << " - (";
421  Overrider.Method->printQualifiedName(Out);
422  Out << ", " << Overrider.Offset.getQuantity() << ')';
423 
424  BaseOffset Offset;
425  if (!Overrider.Method->isPure())
426  Offset = ComputeReturnAdjustmentBaseOffset(Context, Overrider.Method, MD);
427 
428  if (!Offset.isEmpty()) {
429  Out << " [ret-adj: ";
430  if (Offset.VirtualBase) {
431  Offset.VirtualBase->printQualifiedName(Out);
432  Out << " vbase, ";
433  }
434 
435  Out << Offset.NonVirtualOffset.getQuantity() << " nv]";
436  }
437 
438  Out << "\n";
439  }
440 }
441 
442 /// VCallOffsetMap - Keeps track of vcall offsets when building a vtable.
443 struct VCallOffsetMap {
444 
445  typedef std::pair<const CXXMethodDecl *, CharUnits> MethodAndOffsetPairTy;
446 
447  /// Offsets - Keeps track of methods and their offsets.
448  // FIXME: This should be a real map and not a vector.
450 
451  /// MethodsCanShareVCallOffset - Returns whether two virtual member functions
452  /// can share the same vcall offset.
453  static bool MethodsCanShareVCallOffset(const CXXMethodDecl *LHS,
454  const CXXMethodDecl *RHS);
455 
456 public:
457  /// AddVCallOffset - Adds a vcall offset to the map. Returns true if the
458  /// add was successful, or false if there was already a member function with
459  /// the same signature in the map.
460  bool AddVCallOffset(const CXXMethodDecl *MD, CharUnits OffsetOffset);
461 
462  /// getVCallOffsetOffset - Returns the vcall offset offset (relative to the
463  /// vtable address point) for the given virtual member function.
464  CharUnits getVCallOffsetOffset(const CXXMethodDecl *MD);
465 
466  // empty - Return whether the offset map is empty or not.
467  bool empty() const { return Offsets.empty(); }
468 };
469 
470 static bool HasSameVirtualSignature(const CXXMethodDecl *LHS,
471  const CXXMethodDecl *RHS) {
472  const FunctionProtoType *LT =
473  cast<FunctionProtoType>(LHS->getType().getCanonicalType());
474  const FunctionProtoType *RT =
475  cast<FunctionProtoType>(RHS->getType().getCanonicalType());
476 
477  // Fast-path matches in the canonical types.
478  if (LT == RT) return true;
479 
480  // Force the signatures to match. We can't rely on the overrides
481  // list here because there isn't necessarily an inheritance
482  // relationship between the two methods.
483  if (LT->getTypeQuals() != RT->getTypeQuals())
484  return false;
485  return LT->getParamTypes() == RT->getParamTypes();
486 }
487 
488 bool VCallOffsetMap::MethodsCanShareVCallOffset(const CXXMethodDecl *LHS,
489  const CXXMethodDecl *RHS) {
490  assert(LHS->isVirtual() && "LHS must be virtual!");
491  assert(RHS->isVirtual() && "LHS must be virtual!");
492 
493  // A destructor can share a vcall offset with another destructor.
494  if (isa<CXXDestructorDecl>(LHS))
495  return isa<CXXDestructorDecl>(RHS);
496 
497  // FIXME: We need to check more things here.
498 
499  // The methods must have the same name.
500  DeclarationName LHSName = LHS->getDeclName();
501  DeclarationName RHSName = RHS->getDeclName();
502  if (LHSName != RHSName)
503  return false;
504 
505  // And the same signatures.
506  return HasSameVirtualSignature(LHS, RHS);
507 }
508 
509 bool VCallOffsetMap::AddVCallOffset(const CXXMethodDecl *MD,
510  CharUnits OffsetOffset) {
511  // Check if we can reuse an offset.
512  for (const auto &OffsetPair : Offsets) {
513  if (MethodsCanShareVCallOffset(OffsetPair.first, MD))
514  return false;
515  }
516 
517  // Add the offset.
518  Offsets.push_back(MethodAndOffsetPairTy(MD, OffsetOffset));
519  return true;
520 }
521 
522 CharUnits VCallOffsetMap::getVCallOffsetOffset(const CXXMethodDecl *MD) {
523  // Look for an offset.
524  for (const auto &OffsetPair : Offsets) {
525  if (MethodsCanShareVCallOffset(OffsetPair.first, MD))
526  return OffsetPair.second;
527  }
528 
529  llvm_unreachable("Should always find a vcall offset offset!");
530 }
531 
532 /// VCallAndVBaseOffsetBuilder - Class for building vcall and vbase offsets.
533 class VCallAndVBaseOffsetBuilder {
534 public:
535  typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits>
536  VBaseOffsetOffsetsMapTy;
537 
538 private:
539  /// MostDerivedClass - The most derived class for which we're building vcall
540  /// and vbase offsets.
541  const CXXRecordDecl *MostDerivedClass;
542 
543  /// LayoutClass - The class we're using for layout information. Will be
544  /// different than the most derived class if we're building a construction
545  /// vtable.
546  const CXXRecordDecl *LayoutClass;
547 
548  /// Context - The ASTContext which we will use for layout information.
549  ASTContext &Context;
550 
551  /// Components - vcall and vbase offset components
552  typedef SmallVector<VTableComponent, 64> VTableComponentVectorTy;
553  VTableComponentVectorTy Components;
554 
555  /// VisitedVirtualBases - Visited virtual bases.
556  llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBases;
557 
558  /// VCallOffsets - Keeps track of vcall offsets.
559  VCallOffsetMap VCallOffsets;
560 
561 
562  /// VBaseOffsetOffsets - Contains the offsets of the virtual base offsets,
563  /// relative to the address point.
564  VBaseOffsetOffsetsMapTy VBaseOffsetOffsets;
565 
566  /// FinalOverriders - The final overriders of the most derived class.
567  /// (Can be null when we're not building a vtable of the most derived class).
568  const FinalOverriders *Overriders;
569 
570  /// AddVCallAndVBaseOffsets - Add vcall offsets and vbase offsets for the
571  /// given base subobject.
572  void AddVCallAndVBaseOffsets(BaseSubobject Base, bool BaseIsVirtual,
573  CharUnits RealBaseOffset);
574 
575  /// AddVCallOffsets - Add vcall offsets for the given base subobject.
576  void AddVCallOffsets(BaseSubobject Base, CharUnits VBaseOffset);
577 
578  /// AddVBaseOffsets - Add vbase offsets for the given class.
579  void AddVBaseOffsets(const CXXRecordDecl *Base,
580  CharUnits OffsetInLayoutClass);
581 
582  /// getCurrentOffsetOffset - Get the current vcall or vbase offset offset in
583  /// chars, relative to the vtable address point.
584  CharUnits getCurrentOffsetOffset() const;
585 
586 public:
587  VCallAndVBaseOffsetBuilder(const CXXRecordDecl *MostDerivedClass,
588  const CXXRecordDecl *LayoutClass,
589  const FinalOverriders *Overriders,
590  BaseSubobject Base, bool BaseIsVirtual,
591  CharUnits OffsetInLayoutClass)
592  : MostDerivedClass(MostDerivedClass), LayoutClass(LayoutClass),
593  Context(MostDerivedClass->getASTContext()), Overriders(Overriders) {
594 
595  // Add vcall and vbase offsets.
596  AddVCallAndVBaseOffsets(Base, BaseIsVirtual, OffsetInLayoutClass);
597  }
598 
599  /// Methods for iterating over the components.
600  typedef VTableComponentVectorTy::const_reverse_iterator const_iterator;
601  const_iterator components_begin() const { return Components.rbegin(); }
602  const_iterator components_end() const { return Components.rend(); }
603 
604  const VCallOffsetMap &getVCallOffsets() const { return VCallOffsets; }
605  const VBaseOffsetOffsetsMapTy &getVBaseOffsetOffsets() const {
606  return VBaseOffsetOffsets;
607  }
608 };
609 
610 void
611 VCallAndVBaseOffsetBuilder::AddVCallAndVBaseOffsets(BaseSubobject Base,
612  bool BaseIsVirtual,
613  CharUnits RealBaseOffset) {
614  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base.getBase());
615 
616  // Itanium C++ ABI 2.5.2:
617  // ..in classes sharing a virtual table with a primary base class, the vcall
618  // and vbase offsets added by the derived class all come before the vcall
619  // and vbase offsets required by the base class, so that the latter may be
620  // laid out as required by the base class without regard to additions from
621  // the derived class(es).
622 
623  // (Since we're emitting the vcall and vbase offsets in reverse order, we'll
624  // emit them for the primary base first).
625  if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
626  bool PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual();
627 
628  CharUnits PrimaryBaseOffset;
629 
630  // Get the base offset of the primary base.
631  if (PrimaryBaseIsVirtual) {
632  assert(Layout.getVBaseClassOffset(PrimaryBase).isZero() &&
633  "Primary vbase should have a zero offset!");
634 
635  const ASTRecordLayout &MostDerivedClassLayout =
636  Context.getASTRecordLayout(MostDerivedClass);
637 
638  PrimaryBaseOffset =
639  MostDerivedClassLayout.getVBaseClassOffset(PrimaryBase);
640  } else {
641  assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
642  "Primary base should have a zero offset!");
643 
644  PrimaryBaseOffset = Base.getBaseOffset();
645  }
646 
647  AddVCallAndVBaseOffsets(
648  BaseSubobject(PrimaryBase,PrimaryBaseOffset),
649  PrimaryBaseIsVirtual, RealBaseOffset);
650  }
651 
652  AddVBaseOffsets(Base.getBase(), RealBaseOffset);
653 
654  // We only want to add vcall offsets for virtual bases.
655  if (BaseIsVirtual)
656  AddVCallOffsets(Base, RealBaseOffset);
657 }
658 
659 CharUnits VCallAndVBaseOffsetBuilder::getCurrentOffsetOffset() const {
660  // OffsetIndex is the index of this vcall or vbase offset, relative to the
661  // vtable address point. (We subtract 3 to account for the information just
662  // above the address point, the RTTI info, the offset to top, and the
663  // vcall offset itself).
664  int64_t OffsetIndex = -(int64_t)(3 + Components.size());
665 
666  CharUnits PointerWidth =
667  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
668  CharUnits OffsetOffset = PointerWidth * OffsetIndex;
669  return OffsetOffset;
670 }
671 
672 void VCallAndVBaseOffsetBuilder::AddVCallOffsets(BaseSubobject Base,
673  CharUnits VBaseOffset) {
674  const CXXRecordDecl *RD = Base.getBase();
675  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
676 
677  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
678 
679  // Handle the primary base first.
680  // We only want to add vcall offsets if the base is non-virtual; a virtual
681  // primary base will have its vcall and vbase offsets emitted already.
682  if (PrimaryBase && !Layout.isPrimaryBaseVirtual()) {
683  // Get the base offset of the primary base.
684  assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
685  "Primary base should have a zero offset!");
686 
687  AddVCallOffsets(BaseSubobject(PrimaryBase, Base.getBaseOffset()),
688  VBaseOffset);
689  }
690 
691  // Add the vcall offsets.
692  for (const auto *MD : RD->methods()) {
693  if (!MD->isVirtual())
694  continue;
695  MD = MD->getCanonicalDecl();
696 
697  CharUnits OffsetOffset = getCurrentOffsetOffset();
698 
699  // Don't add a vcall offset if we already have one for this member function
700  // signature.
701  if (!VCallOffsets.AddVCallOffset(MD, OffsetOffset))
702  continue;
703 
705 
706  if (Overriders) {
707  // Get the final overrider.
708  FinalOverriders::OverriderInfo Overrider =
709  Overriders->getOverrider(MD, Base.getBaseOffset());
710 
711  /// The vcall offset is the offset from the virtual base to the object
712  /// where the function was overridden.
713  Offset = Overrider.Offset - VBaseOffset;
714  }
715 
716  Components.push_back(
718  }
719 
720  // And iterate over all non-virtual bases (ignoring the primary base).
721  for (const auto &B : RD->bases()) {
722  if (B.isVirtual())
723  continue;
724 
725  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
726  if (BaseDecl == PrimaryBase)
727  continue;
728 
729  // Get the base offset of this base.
730  CharUnits BaseOffset = Base.getBaseOffset() +
731  Layout.getBaseClassOffset(BaseDecl);
732 
733  AddVCallOffsets(BaseSubobject(BaseDecl, BaseOffset),
734  VBaseOffset);
735  }
736 }
737 
738 void
739 VCallAndVBaseOffsetBuilder::AddVBaseOffsets(const CXXRecordDecl *RD,
740  CharUnits OffsetInLayoutClass) {
741  const ASTRecordLayout &LayoutClassLayout =
742  Context.getASTRecordLayout(LayoutClass);
743 
744  // Add vbase offsets.
745  for (const auto &B : RD->bases()) {
746  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
747 
748  // Check if this is a virtual base that we haven't visited before.
749  if (B.isVirtual() && VisitedVirtualBases.insert(BaseDecl).second) {
750  CharUnits Offset =
751  LayoutClassLayout.getVBaseClassOffset(BaseDecl) - OffsetInLayoutClass;
752 
753  // Add the vbase offset offset.
754  assert(!VBaseOffsetOffsets.count(BaseDecl) &&
755  "vbase offset offset already exists!");
756 
757  CharUnits VBaseOffsetOffset = getCurrentOffsetOffset();
758  VBaseOffsetOffsets.insert(
759  std::make_pair(BaseDecl, VBaseOffsetOffset));
760 
761  Components.push_back(
763  }
764 
765  // Check the base class looking for more vbase offsets.
766  AddVBaseOffsets(BaseDecl, OffsetInLayoutClass);
767  }
768 }
769 
770 /// ItaniumVTableBuilder - Class for building vtable layout information.
771 class ItaniumVTableBuilder {
772 public:
773  /// PrimaryBasesSetVectorTy - A set vector of direct and indirect
774  /// primary bases.
776  PrimaryBasesSetVectorTy;
777 
778  typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits>
779  VBaseOffsetOffsetsMapTy;
780 
781  typedef VTableLayout::AddressPointsMapTy AddressPointsMapTy;
782 
783  typedef llvm::DenseMap<GlobalDecl, int64_t> MethodVTableIndicesTy;
784 
785 private:
786  /// VTables - Global vtable information.
787  ItaniumVTableContext &VTables;
788 
789  /// MostDerivedClass - The most derived class for which we're building this
790  /// vtable.
791  const CXXRecordDecl *MostDerivedClass;
792 
793  /// MostDerivedClassOffset - If we're building a construction vtable, this
794  /// holds the offset from the layout class to the most derived class.
795  const CharUnits MostDerivedClassOffset;
796 
797  /// MostDerivedClassIsVirtual - Whether the most derived class is a virtual
798  /// base. (This only makes sense when building a construction vtable).
799  bool MostDerivedClassIsVirtual;
800 
801  /// LayoutClass - The class we're using for layout information. Will be
802  /// different than the most derived class if we're building a construction
803  /// vtable.
804  const CXXRecordDecl *LayoutClass;
805 
806  /// Context - The ASTContext which we will use for layout information.
807  ASTContext &Context;
808 
809  /// FinalOverriders - The final overriders of the most derived class.
810  const FinalOverriders Overriders;
811 
812  /// VCallOffsetsForVBases - Keeps track of vcall offsets for the virtual
813  /// bases in this vtable.
814  llvm::DenseMap<const CXXRecordDecl *, VCallOffsetMap> VCallOffsetsForVBases;
815 
816  /// VBaseOffsetOffsets - Contains the offsets of the virtual base offsets for
817  /// the most derived class.
818  VBaseOffsetOffsetsMapTy VBaseOffsetOffsets;
819 
820  /// Components - The components of the vtable being built.
822 
823  /// AddressPoints - Address points for the vtable being built.
824  AddressPointsMapTy AddressPoints;
825 
826  /// MethodInfo - Contains information about a method in a vtable.
827  /// (Used for computing 'this' pointer adjustment thunks.
828  struct MethodInfo {
829  /// BaseOffset - The base offset of this method.
830  const CharUnits BaseOffset;
831 
832  /// BaseOffsetInLayoutClass - The base offset in the layout class of this
833  /// method.
834  const CharUnits BaseOffsetInLayoutClass;
835 
836  /// VTableIndex - The index in the vtable that this method has.
837  /// (For destructors, this is the index of the complete destructor).
838  const uint64_t VTableIndex;
839 
840  MethodInfo(CharUnits BaseOffset, CharUnits BaseOffsetInLayoutClass,
841  uint64_t VTableIndex)
842  : BaseOffset(BaseOffset),
843  BaseOffsetInLayoutClass(BaseOffsetInLayoutClass),
844  VTableIndex(VTableIndex) { }
845 
846  MethodInfo()
847  : BaseOffset(CharUnits::Zero()),
848  BaseOffsetInLayoutClass(CharUnits::Zero()),
849  VTableIndex(0) { }
850  };
851 
852  typedef llvm::DenseMap<const CXXMethodDecl *, MethodInfo> MethodInfoMapTy;
853 
854  /// MethodInfoMap - The information for all methods in the vtable we're
855  /// currently building.
856  MethodInfoMapTy MethodInfoMap;
857 
858  /// MethodVTableIndices - Contains the index (relative to the vtable address
859  /// point) where the function pointer for a virtual function is stored.
860  MethodVTableIndicesTy MethodVTableIndices;
861 
862  typedef llvm::DenseMap<uint64_t, ThunkInfo> VTableThunksMapTy;
863 
864  /// VTableThunks - The thunks by vtable index in the vtable currently being
865  /// built.
866  VTableThunksMapTy VTableThunks;
867 
868  typedef SmallVector<ThunkInfo, 1> ThunkInfoVectorTy;
869  typedef llvm::DenseMap<const CXXMethodDecl *, ThunkInfoVectorTy> ThunksMapTy;
870 
871  /// Thunks - A map that contains all the thunks needed for all methods in the
872  /// most derived class for which the vtable is currently being built.
873  ThunksMapTy Thunks;
874 
875  /// AddThunk - Add a thunk for the given method.
876  void AddThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk);
877 
878  /// ComputeThisAdjustments - Compute the 'this' pointer adjustments for the
879  /// part of the vtable we're currently building.
880  void ComputeThisAdjustments();
881 
882  typedef llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBasesSetTy;
883 
884  /// PrimaryVirtualBases - All known virtual bases who are a primary base of
885  /// some other base.
886  VisitedVirtualBasesSetTy PrimaryVirtualBases;
887 
888  /// ComputeReturnAdjustment - Compute the return adjustment given a return
889  /// adjustment base offset.
890  ReturnAdjustment ComputeReturnAdjustment(BaseOffset Offset);
891 
892  /// ComputeThisAdjustmentBaseOffset - Compute the base offset for adjusting
893  /// the 'this' pointer from the base subobject to the derived subobject.
894  BaseOffset ComputeThisAdjustmentBaseOffset(BaseSubobject Base,
895  BaseSubobject Derived) const;
896 
897  /// ComputeThisAdjustment - Compute the 'this' pointer adjustment for the
898  /// given virtual member function, its offset in the layout class and its
899  /// final overrider.
901  ComputeThisAdjustment(const CXXMethodDecl *MD,
902  CharUnits BaseOffsetInLayoutClass,
903  FinalOverriders::OverriderInfo Overrider);
904 
905  /// AddMethod - Add a single virtual member function to the vtable
906  /// components vector.
907  void AddMethod(const CXXMethodDecl *MD, ReturnAdjustment ReturnAdjustment);
908 
909  /// IsOverriderUsed - Returns whether the overrider will ever be used in this
910  /// part of the vtable.
911  ///
912  /// Itanium C++ ABI 2.5.2:
913  ///
914  /// struct A { virtual void f(); };
915  /// struct B : virtual public A { int i; };
916  /// struct C : virtual public A { int j; };
917  /// struct D : public B, public C {};
918  ///
919  /// When B and C are declared, A is a primary base in each case, so although
920  /// vcall offsets are allocated in the A-in-B and A-in-C vtables, no this
921  /// adjustment is required and no thunk is generated. However, inside D
922  /// objects, A is no longer a primary base of C, so if we allowed calls to
923  /// C::f() to use the copy of A's vtable in the C subobject, we would need
924  /// to adjust this from C* to B::A*, which would require a third-party
925  /// thunk. Since we require that a call to C::f() first convert to A*,
926  /// C-in-D's copy of A's vtable is never referenced, so this is not
927  /// necessary.
928  bool IsOverriderUsed(const CXXMethodDecl *Overrider,
929  CharUnits BaseOffsetInLayoutClass,
930  const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
931  CharUnits FirstBaseOffsetInLayoutClass) const;
932 
933 
934  /// AddMethods - Add the methods of this base subobject and all its
935  /// primary bases to the vtable components vector.
936  void AddMethods(BaseSubobject Base, CharUnits BaseOffsetInLayoutClass,
937  const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
938  CharUnits FirstBaseOffsetInLayoutClass,
939  PrimaryBasesSetVectorTy &PrimaryBases);
940 
941  // LayoutVTable - Layout the vtable for the given base class, including its
942  // secondary vtables and any vtables for virtual bases.
943  void LayoutVTable();
944 
945  /// LayoutPrimaryAndSecondaryVTables - Layout the primary vtable for the
946  /// given base subobject, as well as all its secondary vtables.
947  ///
948  /// \param BaseIsMorallyVirtual whether the base subobject is a virtual base
949  /// or a direct or indirect base of a virtual base.
950  ///
951  /// \param BaseIsVirtualInLayoutClass - Whether the base subobject is virtual
952  /// in the layout class.
953  void LayoutPrimaryAndSecondaryVTables(BaseSubobject Base,
954  bool BaseIsMorallyVirtual,
955  bool BaseIsVirtualInLayoutClass,
956  CharUnits OffsetInLayoutClass);
957 
958  /// LayoutSecondaryVTables - Layout the secondary vtables for the given base
959  /// subobject.
960  ///
961  /// \param BaseIsMorallyVirtual whether the base subobject is a virtual base
962  /// or a direct or indirect base of a virtual base.
963  void LayoutSecondaryVTables(BaseSubobject Base, bool BaseIsMorallyVirtual,
964  CharUnits OffsetInLayoutClass);
965 
966  /// DeterminePrimaryVirtualBases - Determine the primary virtual bases in this
967  /// class hierarchy.
968  void DeterminePrimaryVirtualBases(const CXXRecordDecl *RD,
969  CharUnits OffsetInLayoutClass,
970  VisitedVirtualBasesSetTy &VBases);
971 
972  /// LayoutVTablesForVirtualBases - Layout vtables for all virtual bases of the
973  /// given base (excluding any primary bases).
974  void LayoutVTablesForVirtualBases(const CXXRecordDecl *RD,
975  VisitedVirtualBasesSetTy &VBases);
976 
977  /// isBuildingConstructionVTable - Return whether this vtable builder is
978  /// building a construction vtable.
979  bool isBuildingConstructorVTable() const {
980  return MostDerivedClass != LayoutClass;
981  }
982 
983 public:
984  /// Component indices of the first component of each of the vtables in the
985  /// vtable group.
986  SmallVector<size_t, 4> VTableIndices;
987 
988  ItaniumVTableBuilder(ItaniumVTableContext &VTables,
989  const CXXRecordDecl *MostDerivedClass,
990  CharUnits MostDerivedClassOffset,
991  bool MostDerivedClassIsVirtual,
992  const CXXRecordDecl *LayoutClass)
993  : VTables(VTables), MostDerivedClass(MostDerivedClass),
994  MostDerivedClassOffset(MostDerivedClassOffset),
995  MostDerivedClassIsVirtual(MostDerivedClassIsVirtual),
996  LayoutClass(LayoutClass), Context(MostDerivedClass->getASTContext()),
997  Overriders(MostDerivedClass, MostDerivedClassOffset, LayoutClass) {
998  assert(!Context.getTargetInfo().getCXXABI().isMicrosoft());
999 
1000  LayoutVTable();
1001 
1002  if (Context.getLangOpts().DumpVTableLayouts)
1003  dumpLayout(llvm::outs());
1004  }
1005 
1006  uint64_t getNumThunks() const {
1007  return Thunks.size();
1008  }
1009 
1010  ThunksMapTy::const_iterator thunks_begin() const {
1011  return Thunks.begin();
1012  }
1013 
1014  ThunksMapTy::const_iterator thunks_end() const {
1015  return Thunks.end();
1016  }
1017 
1018  const VBaseOffsetOffsetsMapTy &getVBaseOffsetOffsets() const {
1019  return VBaseOffsetOffsets;
1020  }
1021 
1022  const AddressPointsMapTy &getAddressPoints() const {
1023  return AddressPoints;
1024  }
1025 
1026  MethodVTableIndicesTy::const_iterator vtable_indices_begin() const {
1027  return MethodVTableIndices.begin();
1028  }
1029 
1030  MethodVTableIndicesTy::const_iterator vtable_indices_end() const {
1031  return MethodVTableIndices.end();
1032  }
1033 
1034  ArrayRef<VTableComponent> vtable_components() const { return Components; }
1035 
1036  AddressPointsMapTy::const_iterator address_points_begin() const {
1037  return AddressPoints.begin();
1038  }
1039 
1040  AddressPointsMapTy::const_iterator address_points_end() const {
1041  return AddressPoints.end();
1042  }
1043 
1044  VTableThunksMapTy::const_iterator vtable_thunks_begin() const {
1045  return VTableThunks.begin();
1046  }
1047 
1048  VTableThunksMapTy::const_iterator vtable_thunks_end() const {
1049  return VTableThunks.end();
1050  }
1051 
1052  /// dumpLayout - Dump the vtable layout.
1053  void dumpLayout(raw_ostream&);
1054 };
1055 
1056 void ItaniumVTableBuilder::AddThunk(const CXXMethodDecl *MD,
1057  const ThunkInfo &Thunk) {
1058  assert(!isBuildingConstructorVTable() &&
1059  "Can't add thunks for construction vtable");
1060 
1061  SmallVectorImpl<ThunkInfo> &ThunksVector = Thunks[MD];
1062 
1063  // Check if we have this thunk already.
1064  if (std::find(ThunksVector.begin(), ThunksVector.end(), Thunk) !=
1065  ThunksVector.end())
1066  return;
1067 
1068  ThunksVector.push_back(Thunk);
1069 }
1070 
1071 typedef llvm::SmallPtrSet<const CXXMethodDecl *, 8> OverriddenMethodsSetTy;
1072 
1073 /// Visit all the methods overridden by the given method recursively,
1074 /// in a depth-first pre-order. The Visitor's visitor method returns a bool
1075 /// indicating whether to continue the recursion for the given overridden
1076 /// method (i.e. returning false stops the iteration).
1077 template <class VisitorTy>
1078 static void
1079 visitAllOverriddenMethods(const CXXMethodDecl *MD, VisitorTy &Visitor) {
1080  assert(MD->isVirtual() && "Method is not virtual!");
1081 
1082  for (const CXXMethodDecl *OverriddenMD : MD->overridden_methods()) {
1083  if (!Visitor(OverriddenMD))
1084  continue;
1085  visitAllOverriddenMethods(OverriddenMD, Visitor);
1086  }
1087 }
1088 
1089 /// ComputeAllOverriddenMethods - Given a method decl, will return a set of all
1090 /// the overridden methods that the function decl overrides.
1091 static void
1092 ComputeAllOverriddenMethods(const CXXMethodDecl *MD,
1093  OverriddenMethodsSetTy& OverriddenMethods) {
1094  auto OverriddenMethodsCollector = [&](const CXXMethodDecl *MD) {
1095  // Don't recurse on this method if we've already collected it.
1096  return OverriddenMethods.insert(MD).second;
1097  };
1098  visitAllOverriddenMethods(MD, OverriddenMethodsCollector);
1099 }
1100 
1101 void ItaniumVTableBuilder::ComputeThisAdjustments() {
1102  // Now go through the method info map and see if any of the methods need
1103  // 'this' pointer adjustments.
1104  for (const auto &MI : MethodInfoMap) {
1105  const CXXMethodDecl *MD = MI.first;
1106  const MethodInfo &MethodInfo = MI.second;
1107 
1108  // Ignore adjustments for unused function pointers.
1109  uint64_t VTableIndex = MethodInfo.VTableIndex;
1110  if (Components[VTableIndex].getKind() ==
1112  continue;
1113 
1114  // Get the final overrider for this method.
1115  FinalOverriders::OverriderInfo Overrider =
1116  Overriders.getOverrider(MD, MethodInfo.BaseOffset);
1117 
1118  // Check if we need an adjustment at all.
1119  if (MethodInfo.BaseOffsetInLayoutClass == Overrider.Offset) {
1120  // When a return thunk is needed by a derived class that overrides a
1121  // virtual base, gcc uses a virtual 'this' adjustment as well.
1122  // While the thunk itself might be needed by vtables in subclasses or
1123  // in construction vtables, there doesn't seem to be a reason for using
1124  // the thunk in this vtable. Still, we do so to match gcc.
1125  if (VTableThunks.lookup(VTableIndex).Return.isEmpty())
1126  continue;
1127  }
1128 
1130  ComputeThisAdjustment(MD, MethodInfo.BaseOffsetInLayoutClass, Overrider);
1131 
1132  if (ThisAdjustment.isEmpty())
1133  continue;
1134 
1135  // Add it.
1136  VTableThunks[VTableIndex].This = ThisAdjustment;
1137 
1138  if (isa<CXXDestructorDecl>(MD)) {
1139  // Add an adjustment for the deleting destructor as well.
1140  VTableThunks[VTableIndex + 1].This = ThisAdjustment;
1141  }
1142  }
1143 
1144  /// Clear the method info map.
1145  MethodInfoMap.clear();
1146 
1147  if (isBuildingConstructorVTable()) {
1148  // We don't need to store thunk information for construction vtables.
1149  return;
1150  }
1151 
1152  for (const auto &TI : VTableThunks) {
1153  const VTableComponent &Component = Components[TI.first];
1154  const ThunkInfo &Thunk = TI.second;
1155  const CXXMethodDecl *MD;
1156 
1157  switch (Component.getKind()) {
1158  default:
1159  llvm_unreachable("Unexpected vtable component kind!");
1161  MD = Component.getFunctionDecl();
1162  break;
1164  MD = Component.getDestructorDecl();
1165  break;
1167  // We've already added the thunk when we saw the complete dtor pointer.
1168  continue;
1169  }
1170 
1171  if (MD->getParent() == MostDerivedClass)
1172  AddThunk(MD, Thunk);
1173  }
1174 }
1175 
1177 ItaniumVTableBuilder::ComputeReturnAdjustment(BaseOffset Offset) {
1178  ReturnAdjustment Adjustment;
1179 
1180  if (!Offset.isEmpty()) {
1181  if (Offset.VirtualBase) {
1182  // Get the virtual base offset offset.
1183  if (Offset.DerivedClass == MostDerivedClass) {
1184  // We can get the offset offset directly from our map.
1185  Adjustment.Virtual.Itanium.VBaseOffsetOffset =
1186  VBaseOffsetOffsets.lookup(Offset.VirtualBase).getQuantity();
1187  } else {
1188  Adjustment.Virtual.Itanium.VBaseOffsetOffset =
1189  VTables.getVirtualBaseOffsetOffset(Offset.DerivedClass,
1190  Offset.VirtualBase).getQuantity();
1191  }
1192  }
1193 
1194  Adjustment.NonVirtual = Offset.NonVirtualOffset.getQuantity();
1195  }
1196 
1197  return Adjustment;
1198 }
1199 
1200 BaseOffset ItaniumVTableBuilder::ComputeThisAdjustmentBaseOffset(
1201  BaseSubobject Base, BaseSubobject Derived) const {
1202  const CXXRecordDecl *BaseRD = Base.getBase();
1203  const CXXRecordDecl *DerivedRD = Derived.getBase();
1204 
1205  CXXBasePaths Paths(/*FindAmbiguities=*/true,
1206  /*RecordPaths=*/true, /*DetectVirtual=*/true);
1207 
1208  if (!DerivedRD->isDerivedFrom(BaseRD, Paths))
1209  llvm_unreachable("Class must be derived from the passed in base class!");
1210 
1211  // We have to go through all the paths, and see which one leads us to the
1212  // right base subobject.
1213  for (const CXXBasePath &Path : Paths) {
1214  BaseOffset Offset = ComputeBaseOffset(Context, DerivedRD, Path);
1215 
1216  CharUnits OffsetToBaseSubobject = Offset.NonVirtualOffset;
1217 
1218  if (Offset.VirtualBase) {
1219  // If we have a virtual base class, the non-virtual offset is relative
1220  // to the virtual base class offset.
1221  const ASTRecordLayout &LayoutClassLayout =
1222  Context.getASTRecordLayout(LayoutClass);
1223 
1224  /// Get the virtual base offset, relative to the most derived class
1225  /// layout.
1226  OffsetToBaseSubobject +=
1227  LayoutClassLayout.getVBaseClassOffset(Offset.VirtualBase);
1228  } else {
1229  // Otherwise, the non-virtual offset is relative to the derived class
1230  // offset.
1231  OffsetToBaseSubobject += Derived.getBaseOffset();
1232  }
1233 
1234  // Check if this path gives us the right base subobject.
1235  if (OffsetToBaseSubobject == Base.getBaseOffset()) {
1236  // Since we're going from the base class _to_ the derived class, we'll
1237  // invert the non-virtual offset here.
1238  Offset.NonVirtualOffset = -Offset.NonVirtualOffset;
1239  return Offset;
1240  }
1241  }
1242 
1243  return BaseOffset();
1244 }
1245 
1246 ThisAdjustment ItaniumVTableBuilder::ComputeThisAdjustment(
1247  const CXXMethodDecl *MD, CharUnits BaseOffsetInLayoutClass,
1248  FinalOverriders::OverriderInfo Overrider) {
1249  // Ignore adjustments for pure virtual member functions.
1250  if (Overrider.Method->isPure())
1251  return ThisAdjustment();
1252 
1253  BaseSubobject OverriddenBaseSubobject(MD->getParent(),
1254  BaseOffsetInLayoutClass);
1255 
1256  BaseSubobject OverriderBaseSubobject(Overrider.Method->getParent(),
1257  Overrider.Offset);
1258 
1259  // Compute the adjustment offset.
1260  BaseOffset Offset = ComputeThisAdjustmentBaseOffset(OverriddenBaseSubobject,
1261  OverriderBaseSubobject);
1262  if (Offset.isEmpty())
1263  return ThisAdjustment();
1264 
1265  ThisAdjustment Adjustment;
1266 
1267  if (Offset.VirtualBase) {
1268  // Get the vcall offset map for this virtual base.
1269  VCallOffsetMap &VCallOffsets = VCallOffsetsForVBases[Offset.VirtualBase];
1270 
1271  if (VCallOffsets.empty()) {
1272  // We don't have vcall offsets for this virtual base, go ahead and
1273  // build them.
1274  VCallAndVBaseOffsetBuilder Builder(MostDerivedClass, MostDerivedClass,
1275  /*FinalOverriders=*/nullptr,
1276  BaseSubobject(Offset.VirtualBase,
1277  CharUnits::Zero()),
1278  /*BaseIsVirtual=*/true,
1279  /*OffsetInLayoutClass=*/
1280  CharUnits::Zero());
1281 
1282  VCallOffsets = Builder.getVCallOffsets();
1283  }
1284 
1285  Adjustment.Virtual.Itanium.VCallOffsetOffset =
1286  VCallOffsets.getVCallOffsetOffset(MD).getQuantity();
1287  }
1288 
1289  // Set the non-virtual part of the adjustment.
1290  Adjustment.NonVirtual = Offset.NonVirtualOffset.getQuantity();
1291 
1292  return Adjustment;
1293 }
1294 
1295 void ItaniumVTableBuilder::AddMethod(const CXXMethodDecl *MD,
1297  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1298  assert(ReturnAdjustment.isEmpty() &&
1299  "Destructor can't have return adjustment!");
1300 
1301  // Add both the complete destructor and the deleting destructor.
1302  Components.push_back(VTableComponent::MakeCompleteDtor(DD));
1303  Components.push_back(VTableComponent::MakeDeletingDtor(DD));
1304  } else {
1305  // Add the return adjustment if necessary.
1306  if (!ReturnAdjustment.isEmpty())
1307  VTableThunks[Components.size()].Return = ReturnAdjustment;
1308 
1309  // Add the function.
1310  Components.push_back(VTableComponent::MakeFunction(MD));
1311  }
1312 }
1313 
1314 /// OverridesIndirectMethodInBase - Return whether the given member function
1315 /// overrides any methods in the set of given bases.
1316 /// Unlike OverridesMethodInBase, this checks "overriders of overriders".
1317 /// For example, if we have:
1318 ///
1319 /// struct A { virtual void f(); }
1320 /// struct B : A { virtual void f(); }
1321 /// struct C : B { virtual void f(); }
1322 ///
1323 /// OverridesIndirectMethodInBase will return true if given C::f as the method
1324 /// and { A } as the set of bases.
1325 static bool OverridesIndirectMethodInBases(
1326  const CXXMethodDecl *MD,
1328  if (Bases.count(MD->getParent()))
1329  return true;
1330 
1331  for (const CXXMethodDecl *OverriddenMD : MD->overridden_methods()) {
1332  // Check "indirect overriders".
1333  if (OverridesIndirectMethodInBases(OverriddenMD, Bases))
1334  return true;
1335  }
1336 
1337  return false;
1338 }
1339 
1340 bool ItaniumVTableBuilder::IsOverriderUsed(
1341  const CXXMethodDecl *Overrider, CharUnits BaseOffsetInLayoutClass,
1342  const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
1343  CharUnits FirstBaseOffsetInLayoutClass) const {
1344  // If the base and the first base in the primary base chain have the same
1345  // offsets, then this overrider will be used.
1346  if (BaseOffsetInLayoutClass == FirstBaseOffsetInLayoutClass)
1347  return true;
1348 
1349  // We know now that Base (or a direct or indirect base of it) is a primary
1350  // base in part of the class hierarchy, but not a primary base in the most
1351  // derived class.
1352 
1353  // If the overrider is the first base in the primary base chain, we know
1354  // that the overrider will be used.
1355  if (Overrider->getParent() == FirstBaseInPrimaryBaseChain)
1356  return true;
1357 
1359 
1360  const CXXRecordDecl *RD = FirstBaseInPrimaryBaseChain;
1361  PrimaryBases.insert(RD);
1362 
1363  // Now traverse the base chain, starting with the first base, until we find
1364  // the base that is no longer a primary base.
1365  while (true) {
1366  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1367  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
1368 
1369  if (!PrimaryBase)
1370  break;
1371 
1372  if (Layout.isPrimaryBaseVirtual()) {
1373  assert(Layout.getVBaseClassOffset(PrimaryBase).isZero() &&
1374  "Primary base should always be at offset 0!");
1375 
1376  const ASTRecordLayout &LayoutClassLayout =
1377  Context.getASTRecordLayout(LayoutClass);
1378 
1379  // Now check if this is the primary base that is not a primary base in the
1380  // most derived class.
1381  if (LayoutClassLayout.getVBaseClassOffset(PrimaryBase) !=
1382  FirstBaseOffsetInLayoutClass) {
1383  // We found it, stop walking the chain.
1384  break;
1385  }
1386  } else {
1387  assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
1388  "Primary base should always be at offset 0!");
1389  }
1390 
1391  if (!PrimaryBases.insert(PrimaryBase))
1392  llvm_unreachable("Found a duplicate primary base!");
1393 
1394  RD = PrimaryBase;
1395  }
1396 
1397  // If the final overrider is an override of one of the primary bases,
1398  // then we know that it will be used.
1399  return OverridesIndirectMethodInBases(Overrider, PrimaryBases);
1400 }
1401 
1402 typedef llvm::SmallSetVector<const CXXRecordDecl *, 8> BasesSetVectorTy;
1403 
1404 /// FindNearestOverriddenMethod - Given a method, returns the overridden method
1405 /// from the nearest base. Returns null if no method was found.
1406 /// The Bases are expected to be sorted in a base-to-derived order.
1407 static const CXXMethodDecl *
1408 FindNearestOverriddenMethod(const CXXMethodDecl *MD,
1409  BasesSetVectorTy &Bases) {
1410  OverriddenMethodsSetTy OverriddenMethods;
1411  ComputeAllOverriddenMethods(MD, OverriddenMethods);
1412 
1413  for (const CXXRecordDecl *PrimaryBase :
1414  llvm::make_range(Bases.rbegin(), Bases.rend())) {
1415  // Now check the overridden methods.
1416  for (const CXXMethodDecl *OverriddenMD : OverriddenMethods) {
1417  // We found our overridden method.
1418  if (OverriddenMD->getParent() == PrimaryBase)
1419  return OverriddenMD;
1420  }
1421  }
1422 
1423  return nullptr;
1424 }
1425 
1426 void ItaniumVTableBuilder::AddMethods(
1427  BaseSubobject Base, CharUnits BaseOffsetInLayoutClass,
1428  const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
1429  CharUnits FirstBaseOffsetInLayoutClass,
1430  PrimaryBasesSetVectorTy &PrimaryBases) {
1431  // Itanium C++ ABI 2.5.2:
1432  // The order of the virtual function pointers in a virtual table is the
1433  // order of declaration of the corresponding member functions in the class.
1434  //
1435  // There is an entry for any virtual function declared in a class,
1436  // whether it is a new function or overrides a base class function,
1437  // unless it overrides a function from the primary base, and conversion
1438  // between their return types does not require an adjustment.
1439 
1440  const CXXRecordDecl *RD = Base.getBase();
1441  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1442 
1443  if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
1444  CharUnits PrimaryBaseOffset;
1445  CharUnits PrimaryBaseOffsetInLayoutClass;
1446  if (Layout.isPrimaryBaseVirtual()) {
1447  assert(Layout.getVBaseClassOffset(PrimaryBase).isZero() &&
1448  "Primary vbase should have a zero offset!");
1449 
1450  const ASTRecordLayout &MostDerivedClassLayout =
1451  Context.getASTRecordLayout(MostDerivedClass);
1452 
1453  PrimaryBaseOffset =
1454  MostDerivedClassLayout.getVBaseClassOffset(PrimaryBase);
1455 
1456  const ASTRecordLayout &LayoutClassLayout =
1457  Context.getASTRecordLayout(LayoutClass);
1458 
1459  PrimaryBaseOffsetInLayoutClass =
1460  LayoutClassLayout.getVBaseClassOffset(PrimaryBase);
1461  } else {
1462  assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
1463  "Primary base should have a zero offset!");
1464 
1465  PrimaryBaseOffset = Base.getBaseOffset();
1466  PrimaryBaseOffsetInLayoutClass = BaseOffsetInLayoutClass;
1467  }
1468 
1469  AddMethods(BaseSubobject(PrimaryBase, PrimaryBaseOffset),
1470  PrimaryBaseOffsetInLayoutClass, FirstBaseInPrimaryBaseChain,
1471  FirstBaseOffsetInLayoutClass, PrimaryBases);
1472 
1473  if (!PrimaryBases.insert(PrimaryBase))
1474  llvm_unreachable("Found a duplicate primary base!");
1475  }
1476 
1477  const CXXDestructorDecl *ImplicitVirtualDtor = nullptr;
1478 
1479  typedef llvm::SmallVector<const CXXMethodDecl *, 8> NewVirtualFunctionsTy;
1480  NewVirtualFunctionsTy NewVirtualFunctions;
1481 
1482  // Now go through all virtual member functions and add them.
1483  for (const auto *MD : RD->methods()) {
1484  if (!MD->isVirtual())
1485  continue;
1486  MD = MD->getCanonicalDecl();
1487 
1488  // Get the final overrider.
1489  FinalOverriders::OverriderInfo Overrider =
1490  Overriders.getOverrider(MD, Base.getBaseOffset());
1491 
1492  // Check if this virtual member function overrides a method in a primary
1493  // base. If this is the case, and the return type doesn't require adjustment
1494  // then we can just use the member function from the primary base.
1495  if (const CXXMethodDecl *OverriddenMD =
1496  FindNearestOverriddenMethod(MD, PrimaryBases)) {
1497  if (ComputeReturnAdjustmentBaseOffset(Context, MD,
1498  OverriddenMD).isEmpty()) {
1499  // Replace the method info of the overridden method with our own
1500  // method.
1501  assert(MethodInfoMap.count(OverriddenMD) &&
1502  "Did not find the overridden method!");
1503  MethodInfo &OverriddenMethodInfo = MethodInfoMap[OverriddenMD];
1504 
1505  MethodInfo MethodInfo(Base.getBaseOffset(), BaseOffsetInLayoutClass,
1506  OverriddenMethodInfo.VTableIndex);
1507 
1508  assert(!MethodInfoMap.count(MD) &&
1509  "Should not have method info for this method yet!");
1510 
1511  MethodInfoMap.insert(std::make_pair(MD, MethodInfo));
1512  MethodInfoMap.erase(OverriddenMD);
1513 
1514  // If the overridden method exists in a virtual base class or a direct
1515  // or indirect base class of a virtual base class, we need to emit a
1516  // thunk if we ever have a class hierarchy where the base class is not
1517  // a primary base in the complete object.
1518  if (!isBuildingConstructorVTable() && OverriddenMD != MD) {
1519  // Compute the this adjustment.
1521  ComputeThisAdjustment(OverriddenMD, BaseOffsetInLayoutClass,
1522  Overrider);
1523 
1524  if (ThisAdjustment.Virtual.Itanium.VCallOffsetOffset &&
1525  Overrider.Method->getParent() == MostDerivedClass) {
1526 
1527  // There's no return adjustment from OverriddenMD and MD,
1528  // but that doesn't mean there isn't one between MD and
1529  // the final overrider.
1530  BaseOffset ReturnAdjustmentOffset =
1531  ComputeReturnAdjustmentBaseOffset(Context, Overrider.Method, MD);
1532  ReturnAdjustment ReturnAdjustment =
1533  ComputeReturnAdjustment(ReturnAdjustmentOffset);
1534 
1535  // This is a virtual thunk for the most derived class, add it.
1536  AddThunk(Overrider.Method,
1537  ThunkInfo(ThisAdjustment, ReturnAdjustment));
1538  }
1539  }
1540 
1541  continue;
1542  }
1543  }
1544 
1545  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1546  if (MD->isImplicit()) {
1547  // Itanium C++ ABI 2.5.2:
1548  // If a class has an implicitly-defined virtual destructor,
1549  // its entries come after the declared virtual function pointers.
1550 
1551  assert(!ImplicitVirtualDtor &&
1552  "Did already see an implicit virtual dtor!");
1553  ImplicitVirtualDtor = DD;
1554  continue;
1555  }
1556  }
1557 
1558  NewVirtualFunctions.push_back(MD);
1559  }
1560 
1561  if (ImplicitVirtualDtor)
1562  NewVirtualFunctions.push_back(ImplicitVirtualDtor);
1563 
1564  for (const CXXMethodDecl *MD : NewVirtualFunctions) {
1565  // Get the final overrider.
1566  FinalOverriders::OverriderInfo Overrider =
1567  Overriders.getOverrider(MD, Base.getBaseOffset());
1568 
1569  // Insert the method info for this method.
1570  MethodInfo MethodInfo(Base.getBaseOffset(), BaseOffsetInLayoutClass,
1571  Components.size());
1572 
1573  assert(!MethodInfoMap.count(MD) &&
1574  "Should not have method info for this method yet!");
1575  MethodInfoMap.insert(std::make_pair(MD, MethodInfo));
1576 
1577  // Check if this overrider is going to be used.
1578  const CXXMethodDecl *OverriderMD = Overrider.Method;
1579  if (!IsOverriderUsed(OverriderMD, BaseOffsetInLayoutClass,
1580  FirstBaseInPrimaryBaseChain,
1581  FirstBaseOffsetInLayoutClass)) {
1582  Components.push_back(VTableComponent::MakeUnusedFunction(OverriderMD));
1583  continue;
1584  }
1585 
1586  // Check if this overrider needs a return adjustment.
1587  // We don't want to do this for pure virtual member functions.
1588  BaseOffset ReturnAdjustmentOffset;
1589  if (!OverriderMD->isPure()) {
1590  ReturnAdjustmentOffset =
1591  ComputeReturnAdjustmentBaseOffset(Context, OverriderMD, MD);
1592  }
1593 
1594  ReturnAdjustment ReturnAdjustment =
1595  ComputeReturnAdjustment(ReturnAdjustmentOffset);
1596 
1597  AddMethod(Overrider.Method, ReturnAdjustment);
1598  }
1599 }
1600 
1601 void ItaniumVTableBuilder::LayoutVTable() {
1602  LayoutPrimaryAndSecondaryVTables(BaseSubobject(MostDerivedClass,
1603  CharUnits::Zero()),
1604  /*BaseIsMorallyVirtual=*/false,
1605  MostDerivedClassIsVirtual,
1606  MostDerivedClassOffset);
1607 
1608  VisitedVirtualBasesSetTy VBases;
1609 
1610  // Determine the primary virtual bases.
1611  DeterminePrimaryVirtualBases(MostDerivedClass, MostDerivedClassOffset,
1612  VBases);
1613  VBases.clear();
1614 
1615  LayoutVTablesForVirtualBases(MostDerivedClass, VBases);
1616 
1617  // -fapple-kext adds an extra entry at end of vtbl.
1618  bool IsAppleKext = Context.getLangOpts().AppleKext;
1619  if (IsAppleKext)
1620  Components.push_back(VTableComponent::MakeVCallOffset(CharUnits::Zero()));
1621 }
1622 
1623 void ItaniumVTableBuilder::LayoutPrimaryAndSecondaryVTables(
1624  BaseSubobject Base, bool BaseIsMorallyVirtual,
1625  bool BaseIsVirtualInLayoutClass, CharUnits OffsetInLayoutClass) {
1626  assert(Base.getBase()->isDynamicClass() && "class does not have a vtable!");
1627 
1628  unsigned VTableIndex = Components.size();
1629  VTableIndices.push_back(VTableIndex);
1630 
1631  // Add vcall and vbase offsets for this vtable.
1632  VCallAndVBaseOffsetBuilder Builder(MostDerivedClass, LayoutClass, &Overriders,
1633  Base, BaseIsVirtualInLayoutClass,
1634  OffsetInLayoutClass);
1635  Components.append(Builder.components_begin(), Builder.components_end());
1636 
1637  // Check if we need to add these vcall offsets.
1638  if (BaseIsVirtualInLayoutClass && !Builder.getVCallOffsets().empty()) {
1639  VCallOffsetMap &VCallOffsets = VCallOffsetsForVBases[Base.getBase()];
1640 
1641  if (VCallOffsets.empty())
1642  VCallOffsets = Builder.getVCallOffsets();
1643  }
1644 
1645  // If we're laying out the most derived class we want to keep track of the
1646  // virtual base class offset offsets.
1647  if (Base.getBase() == MostDerivedClass)
1648  VBaseOffsetOffsets = Builder.getVBaseOffsetOffsets();
1649 
1650  // Add the offset to top.
1651  CharUnits OffsetToTop = MostDerivedClassOffset - OffsetInLayoutClass;
1652  Components.push_back(VTableComponent::MakeOffsetToTop(OffsetToTop));
1653 
1654  // Next, add the RTTI.
1655  Components.push_back(VTableComponent::MakeRTTI(MostDerivedClass));
1656 
1657  uint64_t AddressPoint = Components.size();
1658 
1659  // Now go through all virtual member functions and add them.
1660  PrimaryBasesSetVectorTy PrimaryBases;
1661  AddMethods(Base, OffsetInLayoutClass,
1662  Base.getBase(), OffsetInLayoutClass,
1663  PrimaryBases);
1664 
1665  const CXXRecordDecl *RD = Base.getBase();
1666  if (RD == MostDerivedClass) {
1667  assert(MethodVTableIndices.empty());
1668  for (const auto &I : MethodInfoMap) {
1669  const CXXMethodDecl *MD = I.first;
1670  const MethodInfo &MI = I.second;
1671  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1672  MethodVTableIndices[GlobalDecl(DD, Dtor_Complete)]
1673  = MI.VTableIndex - AddressPoint;
1674  MethodVTableIndices[GlobalDecl(DD, Dtor_Deleting)]
1675  = MI.VTableIndex + 1 - AddressPoint;
1676  } else {
1677  MethodVTableIndices[MD] = MI.VTableIndex - AddressPoint;
1678  }
1679  }
1680  }
1681 
1682  // Compute 'this' pointer adjustments.
1683  ComputeThisAdjustments();
1684 
1685  // Add all address points.
1686  while (true) {
1687  AddressPoints.insert(
1688  std::make_pair(BaseSubobject(RD, OffsetInLayoutClass),
1690  unsigned(VTableIndices.size() - 1),
1691  unsigned(AddressPoint - VTableIndex)}));
1692 
1693  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1694  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
1695 
1696  if (!PrimaryBase)
1697  break;
1698 
1699  if (Layout.isPrimaryBaseVirtual()) {
1700  // Check if this virtual primary base is a primary base in the layout
1701  // class. If it's not, we don't want to add it.
1702  const ASTRecordLayout &LayoutClassLayout =
1703  Context.getASTRecordLayout(LayoutClass);
1704 
1705  if (LayoutClassLayout.getVBaseClassOffset(PrimaryBase) !=
1706  OffsetInLayoutClass) {
1707  // We don't want to add this class (or any of its primary bases).
1708  break;
1709  }
1710  }
1711 
1712  RD = PrimaryBase;
1713  }
1714 
1715  // Layout secondary vtables.
1716  LayoutSecondaryVTables(Base, BaseIsMorallyVirtual, OffsetInLayoutClass);
1717 }
1718 
1719 void
1720 ItaniumVTableBuilder::LayoutSecondaryVTables(BaseSubobject Base,
1721  bool BaseIsMorallyVirtual,
1722  CharUnits OffsetInLayoutClass) {
1723  // Itanium C++ ABI 2.5.2:
1724  // Following the primary virtual table of a derived class are secondary
1725  // virtual tables for each of its proper base classes, except any primary
1726  // base(s) with which it shares its primary virtual table.
1727 
1728  const CXXRecordDecl *RD = Base.getBase();
1729  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1730  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
1731 
1732  for (const auto &B : RD->bases()) {
1733  // Ignore virtual bases, we'll emit them later.
1734  if (B.isVirtual())
1735  continue;
1736 
1737  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
1738 
1739  // Ignore bases that don't have a vtable.
1740  if (!BaseDecl->isDynamicClass())
1741  continue;
1742 
1743  if (isBuildingConstructorVTable()) {
1744  // Itanium C++ ABI 2.6.4:
1745  // Some of the base class subobjects may not need construction virtual
1746  // tables, which will therefore not be present in the construction
1747  // virtual table group, even though the subobject virtual tables are
1748  // present in the main virtual table group for the complete object.
1749  if (!BaseIsMorallyVirtual && !BaseDecl->getNumVBases())
1750  continue;
1751  }
1752 
1753  // Get the base offset of this base.
1754  CharUnits RelativeBaseOffset = Layout.getBaseClassOffset(BaseDecl);
1755  CharUnits BaseOffset = Base.getBaseOffset() + RelativeBaseOffset;
1756 
1757  CharUnits BaseOffsetInLayoutClass =
1758  OffsetInLayoutClass + RelativeBaseOffset;
1759 
1760  // Don't emit a secondary vtable for a primary base. We might however want
1761  // to emit secondary vtables for other bases of this base.
1762  if (BaseDecl == PrimaryBase) {
1763  LayoutSecondaryVTables(BaseSubobject(BaseDecl, BaseOffset),
1764  BaseIsMorallyVirtual, BaseOffsetInLayoutClass);
1765  continue;
1766  }
1767 
1768  // Layout the primary vtable (and any secondary vtables) for this base.
1769  LayoutPrimaryAndSecondaryVTables(
1770  BaseSubobject(BaseDecl, BaseOffset),
1771  BaseIsMorallyVirtual,
1772  /*BaseIsVirtualInLayoutClass=*/false,
1773  BaseOffsetInLayoutClass);
1774  }
1775 }
1776 
1777 void ItaniumVTableBuilder::DeterminePrimaryVirtualBases(
1778  const CXXRecordDecl *RD, CharUnits OffsetInLayoutClass,
1779  VisitedVirtualBasesSetTy &VBases) {
1780  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1781 
1782  // Check if this base has a primary base.
1783  if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
1784 
1785  // Check if it's virtual.
1786  if (Layout.isPrimaryBaseVirtual()) {
1787  bool IsPrimaryVirtualBase = true;
1788 
1789  if (isBuildingConstructorVTable()) {
1790  // Check if the base is actually a primary base in the class we use for
1791  // layout.
1792  const ASTRecordLayout &LayoutClassLayout =
1793  Context.getASTRecordLayout(LayoutClass);
1794 
1795  CharUnits PrimaryBaseOffsetInLayoutClass =
1796  LayoutClassLayout.getVBaseClassOffset(PrimaryBase);
1797 
1798  // We know that the base is not a primary base in the layout class if
1799  // the base offsets are different.
1800  if (PrimaryBaseOffsetInLayoutClass != OffsetInLayoutClass)
1801  IsPrimaryVirtualBase = false;
1802  }
1803 
1804  if (IsPrimaryVirtualBase)
1805  PrimaryVirtualBases.insert(PrimaryBase);
1806  }
1807  }
1808 
1809  // Traverse bases, looking for more primary virtual bases.
1810  for (const auto &B : RD->bases()) {
1811  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
1812 
1813  CharUnits BaseOffsetInLayoutClass;
1814 
1815  if (B.isVirtual()) {
1816  if (!VBases.insert(BaseDecl).second)
1817  continue;
1818 
1819  const ASTRecordLayout &LayoutClassLayout =
1820  Context.getASTRecordLayout(LayoutClass);
1821 
1822  BaseOffsetInLayoutClass =
1823  LayoutClassLayout.getVBaseClassOffset(BaseDecl);
1824  } else {
1825  BaseOffsetInLayoutClass =
1826  OffsetInLayoutClass + Layout.getBaseClassOffset(BaseDecl);
1827  }
1828 
1829  DeterminePrimaryVirtualBases(BaseDecl, BaseOffsetInLayoutClass, VBases);
1830  }
1831 }
1832 
1833 void ItaniumVTableBuilder::LayoutVTablesForVirtualBases(
1834  const CXXRecordDecl *RD, VisitedVirtualBasesSetTy &VBases) {
1835  // Itanium C++ ABI 2.5.2:
1836  // Then come the virtual base virtual tables, also in inheritance graph
1837  // order, and again excluding primary bases (which share virtual tables with
1838  // the classes for which they are primary).
1839  for (const auto &B : RD->bases()) {
1840  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
1841 
1842  // Check if this base needs a vtable. (If it's virtual, not a primary base
1843  // of some other class, and we haven't visited it before).
1844  if (B.isVirtual() && BaseDecl->isDynamicClass() &&
1845  !PrimaryVirtualBases.count(BaseDecl) &&
1846  VBases.insert(BaseDecl).second) {
1847  const ASTRecordLayout &MostDerivedClassLayout =
1848  Context.getASTRecordLayout(MostDerivedClass);
1849  CharUnits BaseOffset =
1850  MostDerivedClassLayout.getVBaseClassOffset(BaseDecl);
1851 
1852  const ASTRecordLayout &LayoutClassLayout =
1853  Context.getASTRecordLayout(LayoutClass);
1854  CharUnits BaseOffsetInLayoutClass =
1855  LayoutClassLayout.getVBaseClassOffset(BaseDecl);
1856 
1857  LayoutPrimaryAndSecondaryVTables(
1858  BaseSubobject(BaseDecl, BaseOffset),
1859  /*BaseIsMorallyVirtual=*/true,
1860  /*BaseIsVirtualInLayoutClass=*/true,
1861  BaseOffsetInLayoutClass);
1862  }
1863 
1864  // We only need to check the base for virtual base vtables if it actually
1865  // has virtual bases.
1866  if (BaseDecl->getNumVBases())
1867  LayoutVTablesForVirtualBases(BaseDecl, VBases);
1868  }
1869 }
1870 
1871 /// dumpLayout - Dump the vtable layout.
1872 void ItaniumVTableBuilder::dumpLayout(raw_ostream &Out) {
1873  // FIXME: write more tests that actually use the dumpLayout output to prevent
1874  // ItaniumVTableBuilder regressions.
1875 
1876  if (isBuildingConstructorVTable()) {
1877  Out << "Construction vtable for ('";
1878  MostDerivedClass->printQualifiedName(Out);
1879  Out << "', ";
1880  Out << MostDerivedClassOffset.getQuantity() << ") in '";
1881  LayoutClass->printQualifiedName(Out);
1882  } else {
1883  Out << "Vtable for '";
1884  MostDerivedClass->printQualifiedName(Out);
1885  }
1886  Out << "' (" << Components.size() << " entries).\n";
1887 
1888  // Iterate through the address points and insert them into a new map where
1889  // they are keyed by the index and not the base object.
1890  // Since an address point can be shared by multiple subobjects, we use an
1891  // STL multimap.
1892  std::multimap<uint64_t, BaseSubobject> AddressPointsByIndex;
1893  for (const auto &AP : AddressPoints) {
1894  const BaseSubobject &Base = AP.first;
1895  uint64_t Index =
1896  VTableIndices[AP.second.VTableIndex] + AP.second.AddressPointIndex;
1897 
1898  AddressPointsByIndex.insert(std::make_pair(Index, Base));
1899  }
1900 
1901  for (unsigned I = 0, E = Components.size(); I != E; ++I) {
1902  uint64_t Index = I;
1903 
1904  Out << llvm::format("%4d | ", I);
1905 
1906  const VTableComponent &Component = Components[I];
1907 
1908  // Dump the component.
1909  switch (Component.getKind()) {
1910 
1912  Out << "vcall_offset ("
1913  << Component.getVCallOffset().getQuantity()
1914  << ")";
1915  break;
1916 
1918  Out << "vbase_offset ("
1919  << Component.getVBaseOffset().getQuantity()
1920  << ")";
1921  break;
1922 
1924  Out << "offset_to_top ("
1925  << Component.getOffsetToTop().getQuantity()
1926  << ")";
1927  break;
1928 
1930  Component.getRTTIDecl()->printQualifiedName(Out);
1931  Out << " RTTI";
1932  break;
1933 
1935  const CXXMethodDecl *MD = Component.getFunctionDecl();
1936 
1937  std::string Str =
1939  MD);
1940  Out << Str;
1941  if (MD->isPure())
1942  Out << " [pure]";
1943 
1944  if (MD->isDeleted())
1945  Out << " [deleted]";
1946 
1947  ThunkInfo Thunk = VTableThunks.lookup(I);
1948  if (!Thunk.isEmpty()) {
1949  // If this function pointer has a return adjustment, dump it.
1950  if (!Thunk.Return.isEmpty()) {
1951  Out << "\n [return adjustment: ";
1952  Out << Thunk.Return.NonVirtual << " non-virtual";
1953 
1955  Out << ", " << Thunk.Return.Virtual.Itanium.VBaseOffsetOffset;
1956  Out << " vbase offset offset";
1957  }
1958 
1959  Out << ']';
1960  }
1961 
1962  // If this function pointer has a 'this' pointer adjustment, dump it.
1963  if (!Thunk.This.isEmpty()) {
1964  Out << "\n [this adjustment: ";
1965  Out << Thunk.This.NonVirtual << " non-virtual";
1966 
1967  if (Thunk.This.Virtual.Itanium.VCallOffsetOffset) {
1968  Out << ", " << Thunk.This.Virtual.Itanium.VCallOffsetOffset;
1969  Out << " vcall offset offset";
1970  }
1971 
1972  Out << ']';
1973  }
1974  }
1975 
1976  break;
1977  }
1978 
1981  bool IsComplete =
1983 
1984  const CXXDestructorDecl *DD = Component.getDestructorDecl();
1985 
1986  DD->printQualifiedName(Out);
1987  if (IsComplete)
1988  Out << "() [complete]";
1989  else
1990  Out << "() [deleting]";
1991 
1992  if (DD->isPure())
1993  Out << " [pure]";
1994 
1995  ThunkInfo Thunk = VTableThunks.lookup(I);
1996  if (!Thunk.isEmpty()) {
1997  // If this destructor has a 'this' pointer adjustment, dump it.
1998  if (!Thunk.This.isEmpty()) {
1999  Out << "\n [this adjustment: ";
2000  Out << Thunk.This.NonVirtual << " non-virtual";
2001 
2002  if (Thunk.This.Virtual.Itanium.VCallOffsetOffset) {
2003  Out << ", " << Thunk.This.Virtual.Itanium.VCallOffsetOffset;
2004  Out << " vcall offset offset";
2005  }
2006 
2007  Out << ']';
2008  }
2009  }
2010 
2011  break;
2012  }
2013 
2015  const CXXMethodDecl *MD = Component.getUnusedFunctionDecl();
2016 
2017  std::string Str =
2019  MD);
2020  Out << "[unused] " << Str;
2021  if (MD->isPure())
2022  Out << " [pure]";
2023  }
2024 
2025  }
2026 
2027  Out << '\n';
2028 
2029  // Dump the next address point.
2030  uint64_t NextIndex = Index + 1;
2031  if (AddressPointsByIndex.count(NextIndex)) {
2032  if (AddressPointsByIndex.count(NextIndex) == 1) {
2033  const BaseSubobject &Base =
2034  AddressPointsByIndex.find(NextIndex)->second;
2035 
2036  Out << " -- (";
2037  Base.getBase()->printQualifiedName(Out);
2038  Out << ", " << Base.getBaseOffset().getQuantity();
2039  Out << ") vtable address --\n";
2040  } else {
2041  CharUnits BaseOffset =
2042  AddressPointsByIndex.lower_bound(NextIndex)->second.getBaseOffset();
2043 
2044  // We store the class names in a set to get a stable order.
2045  std::set<std::string> ClassNames;
2046  for (const auto &I :
2047  llvm::make_range(AddressPointsByIndex.equal_range(NextIndex))) {
2048  assert(I.second.getBaseOffset() == BaseOffset &&
2049  "Invalid base offset!");
2050  const CXXRecordDecl *RD = I.second.getBase();
2051  ClassNames.insert(RD->getQualifiedNameAsString());
2052  }
2053 
2054  for (const std::string &Name : ClassNames) {
2055  Out << " -- (" << Name;
2056  Out << ", " << BaseOffset.getQuantity() << ") vtable address --\n";
2057  }
2058  }
2059  }
2060  }
2061 
2062  Out << '\n';
2063 
2064  if (isBuildingConstructorVTable())
2065  return;
2066 
2067  if (MostDerivedClass->getNumVBases()) {
2068  // We store the virtual base class names and their offsets in a map to get
2069  // a stable order.
2070 
2071  std::map<std::string, CharUnits> ClassNamesAndOffsets;
2072  for (const auto &I : VBaseOffsetOffsets) {
2073  std::string ClassName = I.first->getQualifiedNameAsString();
2074  CharUnits OffsetOffset = I.second;
2075  ClassNamesAndOffsets.insert(std::make_pair(ClassName, OffsetOffset));
2076  }
2077 
2078  Out << "Virtual base offset offsets for '";
2079  MostDerivedClass->printQualifiedName(Out);
2080  Out << "' (";
2081  Out << ClassNamesAndOffsets.size();
2082  Out << (ClassNamesAndOffsets.size() == 1 ? " entry" : " entries") << ").\n";
2083 
2084  for (const auto &I : ClassNamesAndOffsets)
2085  Out << " " << I.first << " | " << I.second.getQuantity() << '\n';
2086 
2087  Out << "\n";
2088  }
2089 
2090  if (!Thunks.empty()) {
2091  // We store the method names in a map to get a stable order.
2092  std::map<std::string, const CXXMethodDecl *> MethodNamesAndDecls;
2093 
2094  for (const auto &I : Thunks) {
2095  const CXXMethodDecl *MD = I.first;
2096  std::string MethodName =
2098  MD);
2099 
2100  MethodNamesAndDecls.insert(std::make_pair(MethodName, MD));
2101  }
2102 
2103  for (const auto &I : MethodNamesAndDecls) {
2104  const std::string &MethodName = I.first;
2105  const CXXMethodDecl *MD = I.second;
2106 
2107  ThunkInfoVectorTy ThunksVector = Thunks[MD];
2108  llvm::sort(ThunksVector.begin(), ThunksVector.end(),
2109  [](const ThunkInfo &LHS, const ThunkInfo &RHS) {
2110  assert(LHS.Method == nullptr && RHS.Method == nullptr);
2111  return std::tie(LHS.This, LHS.Return) < std::tie(RHS.This, RHS.Return);
2112  });
2113 
2114  Out << "Thunks for '" << MethodName << "' (" << ThunksVector.size();
2115  Out << (ThunksVector.size() == 1 ? " entry" : " entries") << ").\n";
2116 
2117  for (unsigned I = 0, E = ThunksVector.size(); I != E; ++I) {
2118  const ThunkInfo &Thunk = ThunksVector[I];
2119 
2120  Out << llvm::format("%4d | ", I);
2121 
2122  // If this function pointer has a return pointer adjustment, dump it.
2123  if (!Thunk.Return.isEmpty()) {
2124  Out << "return adjustment: " << Thunk.Return.NonVirtual;
2125  Out << " non-virtual";
2127  Out << ", " << Thunk.Return.Virtual.Itanium.VBaseOffsetOffset;
2128  Out << " vbase offset offset";
2129  }
2130 
2131  if (!Thunk.This.isEmpty())
2132  Out << "\n ";
2133  }
2134 
2135  // If this function pointer has a 'this' pointer adjustment, dump it.
2136  if (!Thunk.This.isEmpty()) {
2137  Out << "this adjustment: ";
2138  Out << Thunk.This.NonVirtual << " non-virtual";
2139 
2140  if (Thunk.This.Virtual.Itanium.VCallOffsetOffset) {
2141  Out << ", " << Thunk.This.Virtual.Itanium.VCallOffsetOffset;
2142  Out << " vcall offset offset";
2143  }
2144  }
2145 
2146  Out << '\n';
2147  }
2148 
2149  Out << '\n';
2150  }
2151  }
2152 
2153  // Compute the vtable indices for all the member functions.
2154  // Store them in a map keyed by the index so we'll get a sorted table.
2155  std::map<uint64_t, std::string> IndicesMap;
2156 
2157  for (const auto *MD : MostDerivedClass->methods()) {
2158  // We only want virtual member functions.
2159  if (!MD->isVirtual())
2160  continue;
2161  MD = MD->getCanonicalDecl();
2162 
2163  std::string MethodName =
2165  MD);
2166 
2167  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
2168  GlobalDecl GD(DD, Dtor_Complete);
2169  assert(MethodVTableIndices.count(GD));
2170  uint64_t VTableIndex = MethodVTableIndices[GD];
2171  IndicesMap[VTableIndex] = MethodName + " [complete]";
2172  IndicesMap[VTableIndex + 1] = MethodName + " [deleting]";
2173  } else {
2174  assert(MethodVTableIndices.count(MD));
2175  IndicesMap[MethodVTableIndices[MD]] = MethodName;
2176  }
2177  }
2178 
2179  // Print the vtable indices for all the member functions.
2180  if (!IndicesMap.empty()) {
2181  Out << "VTable indices for '";
2182  MostDerivedClass->printQualifiedName(Out);
2183  Out << "' (" << IndicesMap.size() << " entries).\n";
2184 
2185  for (const auto &I : IndicesMap) {
2186  uint64_t VTableIndex = I.first;
2187  const std::string &MethodName = I.second;
2188 
2189  Out << llvm::format("%4" PRIu64 " | ", VTableIndex) << MethodName
2190  << '\n';
2191  }
2192  }
2193 
2194  Out << '\n';
2195 }
2196 }
2197 
2199  ArrayRef<VTableComponent> VTableComponents,
2200  ArrayRef<VTableThunkTy> VTableThunks,
2201  const AddressPointsMapTy &AddressPoints)
2202  : VTableComponents(VTableComponents), VTableThunks(VTableThunks),
2203  AddressPoints(AddressPoints) {
2204  if (VTableIndices.size() <= 1)
2205  assert(VTableIndices.size() == 1 && VTableIndices[0] == 0);
2206  else
2207  this->VTableIndices = OwningArrayRef<size_t>(VTableIndices);
2208 
2209  llvm::sort(this->VTableThunks.begin(), this->VTableThunks.end(),
2210  [](const VTableLayout::VTableThunkTy &LHS,
2211  const VTableLayout::VTableThunkTy &RHS) {
2212  assert((LHS.first != RHS.first || LHS.second == RHS.second) &&
2213  "Different thunks should have unique indices!");
2214  return LHS.first < RHS.first;
2215  });
2216 }
2217 
2219 
2221  : VTableContextBase(/*MS=*/false) {}
2222 
2224 
2226  GD = GD.getCanonicalDecl();
2227  MethodVTableIndicesTy::iterator I = MethodVTableIndices.find(GD);
2228  if (I != MethodVTableIndices.end())
2229  return I->second;
2230 
2231  const CXXRecordDecl *RD = cast<CXXMethodDecl>(GD.getDecl())->getParent();
2232 
2233  computeVTableRelatedInformation(RD);
2234 
2235  I = MethodVTableIndices.find(GD);
2236  assert(I != MethodVTableIndices.end() && "Did not find index!");
2237  return I->second;
2238 }
2239 
2240 CharUnits
2242  const CXXRecordDecl *VBase) {
2243  ClassPairTy ClassPair(RD, VBase);
2244 
2245  VirtualBaseClassOffsetOffsetsMapTy::iterator I =
2246  VirtualBaseClassOffsetOffsets.find(ClassPair);
2247  if (I != VirtualBaseClassOffsetOffsets.end())
2248  return I->second;
2249 
2250  VCallAndVBaseOffsetBuilder Builder(RD, RD, /*FinalOverriders=*/nullptr,
2252  /*BaseIsVirtual=*/false,
2253  /*OffsetInLayoutClass=*/CharUnits::Zero());
2254 
2255  for (const auto &I : Builder.getVBaseOffsetOffsets()) {
2256  // Insert all types.
2257  ClassPairTy ClassPair(RD, I.first);
2258 
2259  VirtualBaseClassOffsetOffsets.insert(std::make_pair(ClassPair, I.second));
2260  }
2261 
2262  I = VirtualBaseClassOffsetOffsets.find(ClassPair);
2263  assert(I != VirtualBaseClassOffsetOffsets.end() && "Did not find index!");
2264 
2265  return I->second;
2266 }
2267 
2268 static std::unique_ptr<VTableLayout>
2269 CreateVTableLayout(const ItaniumVTableBuilder &Builder) {
2271  VTableThunks(Builder.vtable_thunks_begin(), Builder.vtable_thunks_end());
2272 
2273  return llvm::make_unique<VTableLayout>(
2274  Builder.VTableIndices, Builder.vtable_components(), VTableThunks,
2275  Builder.getAddressPoints());
2276 }
2277 
2278 void
2279 ItaniumVTableContext::computeVTableRelatedInformation(const CXXRecordDecl *RD) {
2280  std::unique_ptr<const VTableLayout> &Entry = VTableLayouts[RD];
2281 
2282  // Check if we've computed this information before.
2283  if (Entry)
2284  return;
2285 
2286  ItaniumVTableBuilder Builder(*this, RD, CharUnits::Zero(),
2287  /*MostDerivedClassIsVirtual=*/0, RD);
2288  Entry = CreateVTableLayout(Builder);
2289 
2290  MethodVTableIndices.insert(Builder.vtable_indices_begin(),
2291  Builder.vtable_indices_end());
2292 
2293  // Add the known thunks.
2294  Thunks.insert(Builder.thunks_begin(), Builder.thunks_end());
2295 
2296  // If we don't have the vbase information for this class, insert it.
2297  // getVirtualBaseOffsetOffset will compute it separately without computing
2298  // the rest of the vtable related information.
2299  if (!RD->getNumVBases())
2300  return;
2301 
2302  const CXXRecordDecl *VBase =
2304 
2305  if (VirtualBaseClassOffsetOffsets.count(std::make_pair(RD, VBase)))
2306  return;
2307 
2308  for (const auto &I : Builder.getVBaseOffsetOffsets()) {
2309  // Insert all types.
2310  ClassPairTy ClassPair(RD, I.first);
2311 
2312  VirtualBaseClassOffsetOffsets.insert(std::make_pair(ClassPair, I.second));
2313  }
2314 }
2315 
2316 std::unique_ptr<VTableLayout>
2318  const CXXRecordDecl *MostDerivedClass, CharUnits MostDerivedClassOffset,
2319  bool MostDerivedClassIsVirtual, const CXXRecordDecl *LayoutClass) {
2320  ItaniumVTableBuilder Builder(*this, MostDerivedClass, MostDerivedClassOffset,
2321  MostDerivedClassIsVirtual, LayoutClass);
2322  return CreateVTableLayout(Builder);
2323 }
2324 
2325 namespace {
2326 
2327 // Vtables in the Microsoft ABI are different from the Itanium ABI.
2328 //
2329 // The main differences are:
2330 // 1. Separate vftable and vbtable.
2331 //
2332 // 2. Each subobject with a vfptr gets its own vftable rather than an address
2333 // point in a single vtable shared between all the subobjects.
2334 // Each vftable is represented by a separate section and virtual calls
2335 // must be done using the vftable which has a slot for the function to be
2336 // called.
2337 //
2338 // 3. Virtual method definitions expect their 'this' parameter to point to the
2339 // first vfptr whose table provides a compatible overridden method. In many
2340 // cases, this permits the original vf-table entry to directly call
2341 // the method instead of passing through a thunk.
2342 // See example before VFTableBuilder::ComputeThisOffset below.
2343 //
2344 // A compatible overridden method is one which does not have a non-trivial
2345 // covariant-return adjustment.
2346 //
2347 // The first vfptr is the one with the lowest offset in the complete-object
2348 // layout of the defining class, and the method definition will subtract
2349 // that constant offset from the parameter value to get the real 'this'
2350 // value. Therefore, if the offset isn't really constant (e.g. if a virtual
2351 // function defined in a virtual base is overridden in a more derived
2352 // virtual base and these bases have a reverse order in the complete
2353 // object), the vf-table may require a this-adjustment thunk.
2354 //
2355 // 4. vftables do not contain new entries for overrides that merely require
2356 // this-adjustment. Together with #3, this keeps vf-tables smaller and
2357 // eliminates the need for this-adjustment thunks in many cases, at the cost
2358 // of often requiring redundant work to adjust the "this" pointer.
2359 //
2360 // 5. Instead of VTT and constructor vtables, vbtables and vtordisps are used.
2361 // Vtordisps are emitted into the class layout if a class has
2362 // a) a user-defined ctor/dtor
2363 // and
2364 // b) a method overriding a method in a virtual base.
2365 //
2366 // To get a better understanding of this code,
2367 // you might want to see examples in test/CodeGenCXX/microsoft-abi-vtables-*.cpp
2368 
2369 class VFTableBuilder {
2370 public:
2371  typedef llvm::DenseMap<GlobalDecl, MethodVFTableLocation>
2372  MethodVFTableLocationsTy;
2373 
2374  typedef llvm::iterator_range<MethodVFTableLocationsTy::const_iterator>
2375  method_locations_range;
2376 
2377 private:
2378  /// VTables - Global vtable information.
2379  MicrosoftVTableContext &VTables;
2380 
2381  /// Context - The ASTContext which we will use for layout information.
2382  ASTContext &Context;
2383 
2384  /// MostDerivedClass - The most derived class for which we're building this
2385  /// vtable.
2386  const CXXRecordDecl *MostDerivedClass;
2387 
2388  const ASTRecordLayout &MostDerivedClassLayout;
2389 
2390  const VPtrInfo &WhichVFPtr;
2391 
2392  /// FinalOverriders - The final overriders of the most derived class.
2393  const FinalOverriders Overriders;
2394 
2395  /// Components - The components of the vftable being built.
2397 
2398  MethodVFTableLocationsTy MethodVFTableLocations;
2399 
2400  /// Does this class have an RTTI component?
2401  bool HasRTTIComponent = false;
2402 
2403  /// MethodInfo - Contains information about a method in a vtable.
2404  /// (Used for computing 'this' pointer adjustment thunks.
2405  struct MethodInfo {
2406  /// VBTableIndex - The nonzero index in the vbtable that
2407  /// this method's base has, or zero.
2408  const uint64_t VBTableIndex;
2409 
2410  /// VFTableIndex - The index in the vftable that this method has.
2411  const uint64_t VFTableIndex;
2412 
2413  /// Shadowed - Indicates if this vftable slot is shadowed by
2414  /// a slot for a covariant-return override. If so, it shouldn't be printed
2415  /// or used for vcalls in the most derived class.
2416  bool Shadowed;
2417 
2418  /// UsesExtraSlot - Indicates if this vftable slot was created because
2419  /// any of the overridden slots required a return adjusting thunk.
2420  bool UsesExtraSlot;
2421 
2422  MethodInfo(uint64_t VBTableIndex, uint64_t VFTableIndex,
2423  bool UsesExtraSlot = false)
2424  : VBTableIndex(VBTableIndex), VFTableIndex(VFTableIndex),
2425  Shadowed(false), UsesExtraSlot(UsesExtraSlot) {}
2426 
2427  MethodInfo()
2428  : VBTableIndex(0), VFTableIndex(0), Shadowed(false),
2429  UsesExtraSlot(false) {}
2430  };
2431 
2432  typedef llvm::DenseMap<const CXXMethodDecl *, MethodInfo> MethodInfoMapTy;
2433 
2434  /// MethodInfoMap - The information for all methods in the vftable we're
2435  /// currently building.
2436  MethodInfoMapTy MethodInfoMap;
2437 
2438  typedef llvm::DenseMap<uint64_t, ThunkInfo> VTableThunksMapTy;
2439 
2440  /// VTableThunks - The thunks by vftable index in the vftable currently being
2441  /// built.
2442  VTableThunksMapTy VTableThunks;
2443 
2445  typedef llvm::DenseMap<const CXXMethodDecl *, ThunkInfoVectorTy> ThunksMapTy;
2446 
2447  /// Thunks - A map that contains all the thunks needed for all methods in the
2448  /// most derived class for which the vftable is currently being built.
2449  ThunksMapTy Thunks;
2450 
2451  /// AddThunk - Add a thunk for the given method.
2452  void AddThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk) {
2453  SmallVector<ThunkInfo, 1> &ThunksVector = Thunks[MD];
2454 
2455  // Check if we have this thunk already.
2456  if (std::find(ThunksVector.begin(), ThunksVector.end(), Thunk) !=
2457  ThunksVector.end())
2458  return;
2459 
2460  ThunksVector.push_back(Thunk);
2461  }
2462 
2463  /// ComputeThisOffset - Returns the 'this' argument offset for the given
2464  /// method, relative to the beginning of the MostDerivedClass.
2465  CharUnits ComputeThisOffset(FinalOverriders::OverriderInfo Overrider);
2466 
2467  void CalculateVtordispAdjustment(FinalOverriders::OverriderInfo Overrider,
2468  CharUnits ThisOffset, ThisAdjustment &TA);
2469 
2470  /// AddMethod - Add a single virtual member function to the vftable
2471  /// components vector.
2472  void AddMethod(const CXXMethodDecl *MD, ThunkInfo TI) {
2473  if (!TI.isEmpty()) {
2474  VTableThunks[Components.size()] = TI;
2475  AddThunk(MD, TI);
2476  }
2477  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
2478  assert(TI.Return.isEmpty() &&
2479  "Destructor can't have return adjustment!");
2480  Components.push_back(VTableComponent::MakeDeletingDtor(DD));
2481  } else {
2482  Components.push_back(VTableComponent::MakeFunction(MD));
2483  }
2484  }
2485 
2486  /// AddMethods - Add the methods of this base subobject and the relevant
2487  /// subbases to the vftable we're currently laying out.
2488  void AddMethods(BaseSubobject Base, unsigned BaseDepth,
2489  const CXXRecordDecl *LastVBase,
2490  BasesSetVectorTy &VisitedBases);
2491 
2492  void LayoutVFTable() {
2493  // RTTI data goes before all other entries.
2494  if (HasRTTIComponent)
2495  Components.push_back(VTableComponent::MakeRTTI(MostDerivedClass));
2496 
2497  BasesSetVectorTy VisitedBases;
2498  AddMethods(BaseSubobject(MostDerivedClass, CharUnits::Zero()), 0, nullptr,
2499  VisitedBases);
2500  assert((HasRTTIComponent ? Components.size() - 1 : Components.size()) &&
2501  "vftable can't be empty");
2502 
2503  assert(MethodVFTableLocations.empty());
2504  for (const auto &I : MethodInfoMap) {
2505  const CXXMethodDecl *MD = I.first;
2506  const MethodInfo &MI = I.second;
2507  assert(MD == MD->getCanonicalDecl());
2508 
2509  // Skip the methods that the MostDerivedClass didn't override
2510  // and the entries shadowed by return adjusting thunks.
2511  if (MD->getParent() != MostDerivedClass || MI.Shadowed)
2512  continue;
2513  MethodVFTableLocation Loc(MI.VBTableIndex, WhichVFPtr.getVBaseWithVPtr(),
2514  WhichVFPtr.NonVirtualOffset, MI.VFTableIndex);
2515  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
2516  MethodVFTableLocations[GlobalDecl(DD, Dtor_Deleting)] = Loc;
2517  } else {
2518  MethodVFTableLocations[MD] = Loc;
2519  }
2520  }
2521  }
2522 
2523 public:
2524  VFTableBuilder(MicrosoftVTableContext &VTables,
2525  const CXXRecordDecl *MostDerivedClass, const VPtrInfo &Which)
2526  : VTables(VTables),
2527  Context(MostDerivedClass->getASTContext()),
2528  MostDerivedClass(MostDerivedClass),
2529  MostDerivedClassLayout(Context.getASTRecordLayout(MostDerivedClass)),
2530  WhichVFPtr(Which),
2531  Overriders(MostDerivedClass, CharUnits(), MostDerivedClass) {
2532  // Provide the RTTI component if RTTIData is enabled. If the vftable would
2533  // be available externally, we should not provide the RTTI componenent. It
2534  // is currently impossible to get available externally vftables with either
2535  // dllimport or extern template instantiations, but eventually we may add a
2536  // flag to support additional devirtualization that needs this.
2537  if (Context.getLangOpts().RTTIData)
2538  HasRTTIComponent = true;
2539 
2540  LayoutVFTable();
2541 
2542  if (Context.getLangOpts().DumpVTableLayouts)
2543  dumpLayout(llvm::outs());
2544  }
2545 
2546  uint64_t getNumThunks() const { return Thunks.size(); }
2547 
2548  ThunksMapTy::const_iterator thunks_begin() const { return Thunks.begin(); }
2549 
2550  ThunksMapTy::const_iterator thunks_end() const { return Thunks.end(); }
2551 
2552  method_locations_range vtable_locations() const {
2553  return method_locations_range(MethodVFTableLocations.begin(),
2554  MethodVFTableLocations.end());
2555  }
2556 
2557  ArrayRef<VTableComponent> vtable_components() const { return Components; }
2558 
2559  VTableThunksMapTy::const_iterator vtable_thunks_begin() const {
2560  return VTableThunks.begin();
2561  }
2562 
2563  VTableThunksMapTy::const_iterator vtable_thunks_end() const {
2564  return VTableThunks.end();
2565  }
2566 
2567  void dumpLayout(raw_ostream &);
2568 };
2569 
2570 } // end namespace
2571 
2572 // Let's study one class hierarchy as an example:
2573 // struct A {
2574 // virtual void f();
2575 // int x;
2576 // };
2577 //
2578 // struct B : virtual A {
2579 // virtual void f();
2580 // };
2581 //
2582 // Record layouts:
2583 // struct A:
2584 // 0 | (A vftable pointer)
2585 // 4 | int x
2586 //
2587 // struct B:
2588 // 0 | (B vbtable pointer)
2589 // 4 | struct A (virtual base)
2590 // 4 | (A vftable pointer)
2591 // 8 | int x
2592 //
2593 // Let's assume we have a pointer to the A part of an object of dynamic type B:
2594 // B b;
2595 // A *a = (A*)&b;
2596 // a->f();
2597 //
2598 // In this hierarchy, f() belongs to the vftable of A, so B::f() expects
2599 // "this" parameter to point at the A subobject, which is B+4.
2600 // In the B::f() prologue, it adjusts "this" back to B by subtracting 4,
2601 // performed as a *static* adjustment.
2602 //
2603 // Interesting thing happens when we alter the relative placement of A and B
2604 // subobjects in a class:
2605 // struct C : virtual B { };
2606 //
2607 // C c;
2608 // A *a = (A*)&c;
2609 // a->f();
2610 //
2611 // Respective record layout is:
2612 // 0 | (C vbtable pointer)
2613 // 4 | struct A (virtual base)
2614 // 4 | (A vftable pointer)
2615 // 8 | int x
2616 // 12 | struct B (virtual base)
2617 // 12 | (B vbtable pointer)
2618 //
2619 // The final overrider of f() in class C is still B::f(), so B+4 should be
2620 // passed as "this" to that code. However, "a" points at B-8, so the respective
2621 // vftable entry should hold a thunk that adds 12 to the "this" argument before
2622 // performing a tail call to B::f().
2623 //
2624 // With this example in mind, we can now calculate the 'this' argument offset
2625 // for the given method, relative to the beginning of the MostDerivedClass.
2626 CharUnits
2627 VFTableBuilder::ComputeThisOffset(FinalOverriders::OverriderInfo Overrider) {
2628  BasesSetVectorTy Bases;
2629 
2630  {
2631  // Find the set of least derived bases that define the given method.
2632  OverriddenMethodsSetTy VisitedOverriddenMethods;
2633  auto InitialOverriddenDefinitionCollector = [&](
2634  const CXXMethodDecl *OverriddenMD) {
2635  if (OverriddenMD->size_overridden_methods() == 0)
2636  Bases.insert(OverriddenMD->getParent());
2637  // Don't recurse on this method if we've already collected it.
2638  return VisitedOverriddenMethods.insert(OverriddenMD).second;
2639  };
2640  visitAllOverriddenMethods(Overrider.Method,
2641  InitialOverriddenDefinitionCollector);
2642  }
2643 
2644  // If there are no overrides then 'this' is located
2645  // in the base that defines the method.
2646  if (Bases.size() == 0)
2647  return Overrider.Offset;
2648 
2649  CXXBasePaths Paths;
2650  Overrider.Method->getParent()->lookupInBases(
2651  [&Bases](const CXXBaseSpecifier *Specifier, CXXBasePath &) {
2652  return Bases.count(Specifier->getType()->getAsCXXRecordDecl());
2653  },
2654  Paths);
2655 
2656  // This will hold the smallest this offset among overridees of MD.
2657  // This implies that an offset of a non-virtual base will dominate an offset
2658  // of a virtual base to potentially reduce the number of thunks required
2659  // in the derived classes that inherit this method.
2660  CharUnits Ret;
2661  bool First = true;
2662 
2663  const ASTRecordLayout &OverriderRDLayout =
2664  Context.getASTRecordLayout(Overrider.Method->getParent());
2665  for (const CXXBasePath &Path : Paths) {
2666  CharUnits ThisOffset = Overrider.Offset;
2667  CharUnits LastVBaseOffset;
2668 
2669  // For each path from the overrider to the parents of the overridden
2670  // methods, traverse the path, calculating the this offset in the most
2671  // derived class.
2672  for (const CXXBasePathElement &Element : Path) {
2673  QualType CurTy = Element.Base->getType();
2674  const CXXRecordDecl *PrevRD = Element.Class,
2675  *CurRD = CurTy->getAsCXXRecordDecl();
2676  const ASTRecordLayout &Layout = Context.getASTRecordLayout(PrevRD);
2677 
2678  if (Element.Base->isVirtual()) {
2679  // The interesting things begin when you have virtual inheritance.
2680  // The final overrider will use a static adjustment equal to the offset
2681  // of the vbase in the final overrider class.
2682  // For example, if the final overrider is in a vbase B of the most
2683  // derived class and it overrides a method of the B's own vbase A,
2684  // it uses A* as "this". In its prologue, it can cast A* to B* with
2685  // a static offset. This offset is used regardless of the actual
2686  // offset of A from B in the most derived class, requiring an
2687  // this-adjusting thunk in the vftable if A and B are laid out
2688  // differently in the most derived class.
2689  LastVBaseOffset = ThisOffset =
2690  Overrider.Offset + OverriderRDLayout.getVBaseClassOffset(CurRD);
2691  } else {
2692  ThisOffset += Layout.getBaseClassOffset(CurRD);
2693  }
2694  }
2695 
2696  if (isa<CXXDestructorDecl>(Overrider.Method)) {
2697  if (LastVBaseOffset.isZero()) {
2698  // If a "Base" class has at least one non-virtual base with a virtual
2699  // destructor, the "Base" virtual destructor will take the address
2700  // of the "Base" subobject as the "this" argument.
2701  ThisOffset = Overrider.Offset;
2702  } else {
2703  // A virtual destructor of a virtual base takes the address of the
2704  // virtual base subobject as the "this" argument.
2705  ThisOffset = LastVBaseOffset;
2706  }
2707  }
2708 
2709  if (Ret > ThisOffset || First) {
2710  First = false;
2711  Ret = ThisOffset;
2712  }
2713  }
2714 
2715  assert(!First && "Method not found in the given subobject?");
2716  return Ret;
2717 }
2718 
2719 // Things are getting even more complex when the "this" adjustment has to
2720 // use a dynamic offset instead of a static one, or even two dynamic offsets.
2721 // This is sometimes required when a virtual call happens in the middle of
2722 // a non-most-derived class construction or destruction.
2723 //
2724 // Let's take a look at the following example:
2725 // struct A {
2726 // virtual void f();
2727 // };
2728 //
2729 // void foo(A *a) { a->f(); } // Knows nothing about siblings of A.
2730 //
2731 // struct B : virtual A {
2732 // virtual void f();
2733 // B() {
2734 // foo(this);
2735 // }
2736 // };
2737 //
2738 // struct C : virtual B {
2739 // virtual void f();
2740 // };
2741 //
2742 // Record layouts for these classes are:
2743 // struct A
2744 // 0 | (A vftable pointer)
2745 //
2746 // struct B
2747 // 0 | (B vbtable pointer)
2748 // 4 | (vtordisp for vbase A)
2749 // 8 | struct A (virtual base)
2750 // 8 | (A vftable pointer)
2751 //
2752 // struct C
2753 // 0 | (C vbtable pointer)
2754 // 4 | (vtordisp for vbase A)
2755 // 8 | struct A (virtual base) // A precedes B!
2756 // 8 | (A vftable pointer)
2757 // 12 | struct B (virtual base)
2758 // 12 | (B vbtable pointer)
2759 //
2760 // When one creates an object of type C, the C constructor:
2761 // - initializes all the vbptrs, then
2762 // - calls the A subobject constructor
2763 // (initializes A's vfptr with an address of A vftable), then
2764 // - calls the B subobject constructor
2765 // (initializes A's vfptr with an address of B vftable and vtordisp for A),
2766 // that in turn calls foo(), then
2767 // - initializes A's vfptr with an address of C vftable and zeroes out the
2768 // vtordisp
2769 // FIXME: if a structor knows it belongs to MDC, why doesn't it use a vftable
2770 // without vtordisp thunks?
2771 // FIXME: how are vtordisp handled in the presence of nooverride/final?
2772 //
2773 // When foo() is called, an object with a layout of class C has a vftable
2774 // referencing B::f() that assumes a B layout, so the "this" adjustments are
2775 // incorrect, unless an extra adjustment is done. This adjustment is called
2776 // "vtordisp adjustment". Vtordisp basically holds the difference between the
2777 // actual location of a vbase in the layout class and the location assumed by
2778 // the vftable of the class being constructed/destructed. Vtordisp is only
2779 // needed if "this" escapes a
2780 // structor (or we can't prove otherwise).
2781 // [i.e. vtordisp is a dynamic adjustment for a static adjustment, which is an
2782 // estimation of a dynamic adjustment]
2783 //
2784 // foo() gets a pointer to the A vbase and doesn't know anything about B or C,
2785 // so it just passes that pointer as "this" in a virtual call.
2786 // If there was no vtordisp, that would just dispatch to B::f().
2787 // However, B::f() assumes B+8 is passed as "this",
2788 // yet the pointer foo() passes along is B-4 (i.e. C+8).
2789 // An extra adjustment is needed, so we emit a thunk into the B vftable.
2790 // This vtordisp thunk subtracts the value of vtordisp
2791 // from the "this" argument (-12) before making a tailcall to B::f().
2792 //
2793 // Let's consider an even more complex example:
2794 // struct D : virtual B, virtual C {
2795 // D() {
2796 // foo(this);
2797 // }
2798 // };
2799 //
2800 // struct D
2801 // 0 | (D vbtable pointer)
2802 // 4 | (vtordisp for vbase A)
2803 // 8 | struct A (virtual base) // A precedes both B and C!
2804 // 8 | (A vftable pointer)
2805 // 12 | struct B (virtual base) // B precedes C!
2806 // 12 | (B vbtable pointer)
2807 // 16 | struct C (virtual base)
2808 // 16 | (C vbtable pointer)
2809 //
2810 // When D::D() calls foo(), we find ourselves in a thunk that should tailcall
2811 // to C::f(), which assumes C+8 as its "this" parameter. This time, foo()
2812 // passes along A, which is C-8. The A vtordisp holds
2813 // "D.vbptr[index_of_A] - offset_of_A_in_D"
2814 // and we statically know offset_of_A_in_D, so can get a pointer to D.
2815 // When we know it, we can make an extra vbtable lookup to locate the C vbase
2816 // and one extra static adjustment to calculate the expected value of C+8.
2817 void VFTableBuilder::CalculateVtordispAdjustment(
2818  FinalOverriders::OverriderInfo Overrider, CharUnits ThisOffset,
2819  ThisAdjustment &TA) {
2820  const ASTRecordLayout::VBaseOffsetsMapTy &VBaseMap =
2821  MostDerivedClassLayout.getVBaseOffsetsMap();
2822  const ASTRecordLayout::VBaseOffsetsMapTy::const_iterator &VBaseMapEntry =
2823  VBaseMap.find(WhichVFPtr.getVBaseWithVPtr());
2824  assert(VBaseMapEntry != VBaseMap.end());
2825 
2826  // If there's no vtordisp or the final overrider is defined in the same vbase
2827  // as the initial declaration, we don't need any vtordisp adjustment.
2828  if (!VBaseMapEntry->second.hasVtorDisp() ||
2829  Overrider.VirtualBase == WhichVFPtr.getVBaseWithVPtr())
2830  return;
2831 
2832  // OK, now we know we need to use a vtordisp thunk.
2833  // The implicit vtordisp field is located right before the vbase.
2834  CharUnits OffsetOfVBaseWithVFPtr = VBaseMapEntry->second.VBaseOffset;
2836  (OffsetOfVBaseWithVFPtr - WhichVFPtr.FullOffsetInMDC).getQuantity() - 4;
2837 
2838  // A simple vtordisp thunk will suffice if the final overrider is defined
2839  // in either the most derived class or its non-virtual base.
2840  if (Overrider.Method->getParent() == MostDerivedClass ||
2841  !Overrider.VirtualBase)
2842  return;
2843 
2844  // Otherwise, we need to do use the dynamic offset of the final overrider
2845  // in order to get "this" adjustment right.
2847  (OffsetOfVBaseWithVFPtr + WhichVFPtr.NonVirtualOffset -
2848  MostDerivedClassLayout.getVBPtrOffset()).getQuantity();
2850  Context.getTypeSizeInChars(Context.IntTy).getQuantity() *
2851  VTables.getVBTableIndex(MostDerivedClass, Overrider.VirtualBase);
2852 
2853  TA.NonVirtual = (ThisOffset - Overrider.Offset).getQuantity();
2854 }
2855 
2857  const CXXRecordDecl *RD,
2858  SmallVector<const CXXMethodDecl *, 10> &VirtualMethods) {
2859  // Put the virtual methods into VirtualMethods in the proper order:
2860  // 1) Group overloads by declaration name. New groups are added to the
2861  // vftable in the order of their first declarations in this class
2862  // (including overrides, non-virtual methods and any other named decl that
2863  // might be nested within the class).
2864  // 2) In each group, new overloads appear in the reverse order of declaration.
2865  typedef SmallVector<const CXXMethodDecl *, 1> MethodGroup;
2867  typedef llvm::DenseMap<DeclarationName, unsigned> VisitedGroupIndicesTy;
2868  VisitedGroupIndicesTy VisitedGroupIndices;
2869  for (const auto *D : RD->decls()) {
2870  const auto *ND = dyn_cast<NamedDecl>(D);
2871  if (!ND)
2872  continue;
2873  VisitedGroupIndicesTy::iterator J;
2874  bool Inserted;
2875  std::tie(J, Inserted) = VisitedGroupIndices.insert(
2876  std::make_pair(ND->getDeclName(), Groups.size()));
2877  if (Inserted)
2878  Groups.push_back(MethodGroup());
2879  if (const auto *MD = dyn_cast<CXXMethodDecl>(ND))
2880  if (MD->isVirtual())
2881  Groups[J->second].push_back(MD->getCanonicalDecl());
2882  }
2883 
2884  for (const MethodGroup &Group : Groups)
2885  VirtualMethods.append(Group.rbegin(), Group.rend());
2886 }
2887 
2888 static bool isDirectVBase(const CXXRecordDecl *Base, const CXXRecordDecl *RD) {
2889  for (const auto &B : RD->bases()) {
2890  if (B.isVirtual() && B.getType()->getAsCXXRecordDecl() == Base)
2891  return true;
2892  }
2893  return false;
2894 }
2895 
2896 void VFTableBuilder::AddMethods(BaseSubobject Base, unsigned BaseDepth,
2897  const CXXRecordDecl *LastVBase,
2898  BasesSetVectorTy &VisitedBases) {
2899  const CXXRecordDecl *RD = Base.getBase();
2900  if (!RD->isPolymorphic())
2901  return;
2902 
2903  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
2904 
2905  // See if this class expands a vftable of the base we look at, which is either
2906  // the one defined by the vfptr base path or the primary base of the current
2907  // class.
2908  const CXXRecordDecl *NextBase = nullptr, *NextLastVBase = LastVBase;
2909  CharUnits NextBaseOffset;
2910  if (BaseDepth < WhichVFPtr.PathToIntroducingObject.size()) {
2911  NextBase = WhichVFPtr.PathToIntroducingObject[BaseDepth];
2912  if (isDirectVBase(NextBase, RD)) {
2913  NextLastVBase = NextBase;
2914  NextBaseOffset = MostDerivedClassLayout.getVBaseClassOffset(NextBase);
2915  } else {
2916  NextBaseOffset =
2917  Base.getBaseOffset() + Layout.getBaseClassOffset(NextBase);
2918  }
2919  } else if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
2920  assert(!Layout.isPrimaryBaseVirtual() &&
2921  "No primary virtual bases in this ABI");
2922  NextBase = PrimaryBase;
2923  NextBaseOffset = Base.getBaseOffset();
2924  }
2925 
2926  if (NextBase) {
2927  AddMethods(BaseSubobject(NextBase, NextBaseOffset), BaseDepth + 1,
2928  NextLastVBase, VisitedBases);
2929  if (!VisitedBases.insert(NextBase))
2930  llvm_unreachable("Found a duplicate primary base!");
2931  }
2932 
2934  // Put virtual methods in the proper order.
2935  GroupNewVirtualOverloads(RD, VirtualMethods);
2936 
2937  // Now go through all virtual member functions and add them to the current
2938  // vftable. This is done by
2939  // - replacing overridden methods in their existing slots, as long as they
2940  // don't require return adjustment; calculating This adjustment if needed.
2941  // - adding new slots for methods of the current base not present in any
2942  // sub-bases;
2943  // - adding new slots for methods that require Return adjustment.
2944  // We keep track of the methods visited in the sub-bases in MethodInfoMap.
2945  for (const CXXMethodDecl *MD : VirtualMethods) {
2946  FinalOverriders::OverriderInfo FinalOverrider =
2947  Overriders.getOverrider(MD, Base.getBaseOffset());
2948  const CXXMethodDecl *FinalOverriderMD = FinalOverrider.Method;
2949  const CXXMethodDecl *OverriddenMD =
2950  FindNearestOverriddenMethod(MD, VisitedBases);
2951 
2952  ThisAdjustment ThisAdjustmentOffset;
2953  bool ReturnAdjustingThunk = false, ForceReturnAdjustmentMangling = false;
2954  CharUnits ThisOffset = ComputeThisOffset(FinalOverrider);
2955  ThisAdjustmentOffset.NonVirtual =
2956  (ThisOffset - WhichVFPtr.FullOffsetInMDC).getQuantity();
2957  if ((OverriddenMD || FinalOverriderMD != MD) &&
2958  WhichVFPtr.getVBaseWithVPtr())
2959  CalculateVtordispAdjustment(FinalOverrider, ThisOffset,
2960  ThisAdjustmentOffset);
2961 
2962  unsigned VBIndex =
2963  LastVBase ? VTables.getVBTableIndex(MostDerivedClass, LastVBase) : 0;
2964 
2965  if (OverriddenMD) {
2966  // If MD overrides anything in this vftable, we need to update the
2967  // entries.
2968  MethodInfoMapTy::iterator OverriddenMDIterator =
2969  MethodInfoMap.find(OverriddenMD);
2970 
2971  // If the overridden method went to a different vftable, skip it.
2972  if (OverriddenMDIterator == MethodInfoMap.end())
2973  continue;
2974 
2975  MethodInfo &OverriddenMethodInfo = OverriddenMDIterator->second;
2976 
2977  VBIndex = OverriddenMethodInfo.VBTableIndex;
2978 
2979  // Let's check if the overrider requires any return adjustments.
2980  // We must create a new slot if the MD's return type is not trivially
2981  // convertible to the OverriddenMD's one.
2982  // Once a chain of method overrides adds a return adjusting vftable slot,
2983  // all subsequent overrides will also use an extra method slot.
2984  ReturnAdjustingThunk = !ComputeReturnAdjustmentBaseOffset(
2985  Context, MD, OverriddenMD).isEmpty() ||
2986  OverriddenMethodInfo.UsesExtraSlot;
2987 
2988  if (!ReturnAdjustingThunk) {
2989  // No return adjustment needed - just replace the overridden method info
2990  // with the current info.
2991  MethodInfo MI(VBIndex, OverriddenMethodInfo.VFTableIndex);
2992  MethodInfoMap.erase(OverriddenMDIterator);
2993 
2994  assert(!MethodInfoMap.count(MD) &&
2995  "Should not have method info for this method yet!");
2996  MethodInfoMap.insert(std::make_pair(MD, MI));
2997  continue;
2998  }
2999 
3000  // In case we need a return adjustment, we'll add a new slot for
3001  // the overrider. Mark the overridden method as shadowed by the new slot.
3002  OverriddenMethodInfo.Shadowed = true;
3003 
3004  // Force a special name mangling for a return-adjusting thunk
3005  // unless the method is the final overrider without this adjustment.
3006  ForceReturnAdjustmentMangling =
3007  !(MD == FinalOverriderMD && ThisAdjustmentOffset.isEmpty());
3008  } else if (Base.getBaseOffset() != WhichVFPtr.FullOffsetInMDC ||
3009  MD->size_overridden_methods()) {
3010  // Skip methods that don't belong to the vftable of the current class,
3011  // e.g. each method that wasn't seen in any of the visited sub-bases
3012  // but overrides multiple methods of other sub-bases.
3013  continue;
3014  }
3015 
3016  // If we got here, MD is a method not seen in any of the sub-bases or
3017  // it requires return adjustment. Insert the method info for this method.
3018  MethodInfo MI(VBIndex,
3019  HasRTTIComponent ? Components.size() - 1 : Components.size(),
3020  ReturnAdjustingThunk);
3021 
3022  assert(!MethodInfoMap.count(MD) &&
3023  "Should not have method info for this method yet!");
3024  MethodInfoMap.insert(std::make_pair(MD, MI));
3025 
3026  // Check if this overrider needs a return adjustment.
3027  // We don't want to do this for pure virtual member functions.
3028  BaseOffset ReturnAdjustmentOffset;
3030  if (!FinalOverriderMD->isPure()) {
3031  ReturnAdjustmentOffset =
3032  ComputeReturnAdjustmentBaseOffset(Context, FinalOverriderMD, MD);
3033  }
3034  if (!ReturnAdjustmentOffset.isEmpty()) {
3035  ForceReturnAdjustmentMangling = true;
3036  ReturnAdjustment.NonVirtual =
3037  ReturnAdjustmentOffset.NonVirtualOffset.getQuantity();
3038  if (ReturnAdjustmentOffset.VirtualBase) {
3039  const ASTRecordLayout &DerivedLayout =
3040  Context.getASTRecordLayout(ReturnAdjustmentOffset.DerivedClass);
3041  ReturnAdjustment.Virtual.Microsoft.VBPtrOffset =
3042  DerivedLayout.getVBPtrOffset().getQuantity();
3043  ReturnAdjustment.Virtual.Microsoft.VBIndex =
3044  VTables.getVBTableIndex(ReturnAdjustmentOffset.DerivedClass,
3045  ReturnAdjustmentOffset.VirtualBase);
3046  }
3047  }
3048 
3049  AddMethod(FinalOverriderMD,
3050  ThunkInfo(ThisAdjustmentOffset, ReturnAdjustment,
3051  ForceReturnAdjustmentMangling ? MD : nullptr));
3052  }
3053 }
3054 
3055 static void PrintBasePath(const VPtrInfo::BasePath &Path, raw_ostream &Out) {
3056  for (const CXXRecordDecl *Elem :
3057  llvm::make_range(Path.rbegin(), Path.rend())) {
3058  Out << "'";
3059  Elem->printQualifiedName(Out);
3060  Out << "' in ";
3061  }
3062 }
3063 
3064 static void dumpMicrosoftThunkAdjustment(const ThunkInfo &TI, raw_ostream &Out,
3065  bool ContinueFirstLine) {
3066  const ReturnAdjustment &R = TI.Return;
3067  bool Multiline = false;
3068  const char *LinePrefix = "\n ";
3069  if (!R.isEmpty() || TI.Method) {
3070  if (!ContinueFirstLine)
3071  Out << LinePrefix;
3072  Out << "[return adjustment (to type '"
3074  << "'): ";
3076  Out << "vbptr at offset " << R.Virtual.Microsoft.VBPtrOffset << ", ";
3077  if (R.Virtual.Microsoft.VBIndex)
3078  Out << "vbase #" << R.Virtual.Microsoft.VBIndex << ", ";
3079  Out << R.NonVirtual << " non-virtual]";
3080  Multiline = true;
3081  }
3082 
3083  const ThisAdjustment &T = TI.This;
3084  if (!T.isEmpty()) {
3085  if (Multiline || !ContinueFirstLine)
3086  Out << LinePrefix;
3087  Out << "[this adjustment: ";
3088  if (!TI.This.Virtual.isEmpty()) {
3089  assert(T.Virtual.Microsoft.VtordispOffset < 0);
3090  Out << "vtordisp at " << T.Virtual.Microsoft.VtordispOffset << ", ";
3091  if (T.Virtual.Microsoft.VBPtrOffset) {
3092  Out << "vbptr at " << T.Virtual.Microsoft.VBPtrOffset
3093  << " to the left,";
3094  assert(T.Virtual.Microsoft.VBOffsetOffset > 0);
3095  Out << LinePrefix << " vboffset at "
3096  << T.Virtual.Microsoft.VBOffsetOffset << " in the vbtable, ";
3097  }
3098  }
3099  Out << T.NonVirtual << " non-virtual]";
3100  }
3101 }
3102 
3103 void VFTableBuilder::dumpLayout(raw_ostream &Out) {
3104  Out << "VFTable for ";
3105  PrintBasePath(WhichVFPtr.PathToIntroducingObject, Out);
3106  Out << "'";
3107  MostDerivedClass->printQualifiedName(Out);
3108  Out << "' (" << Components.size()
3109  << (Components.size() == 1 ? " entry" : " entries") << ").\n";
3110 
3111  for (unsigned I = 0, E = Components.size(); I != E; ++I) {
3112  Out << llvm::format("%4d | ", I);
3113 
3114  const VTableComponent &Component = Components[I];
3115 
3116  // Dump the component.
3117  switch (Component.getKind()) {
3119  Component.getRTTIDecl()->printQualifiedName(Out);
3120  Out << " RTTI";
3121  break;
3122 
3124  const CXXMethodDecl *MD = Component.getFunctionDecl();
3125 
3126  // FIXME: Figure out how to print the real thunk type, since they can
3127  // differ in the return type.
3128  std::string Str = PredefinedExpr::ComputeName(
3130  Out << Str;
3131  if (MD->isPure())
3132  Out << " [pure]";
3133 
3134  if (MD->isDeleted())
3135  Out << " [deleted]";
3136 
3137  ThunkInfo Thunk = VTableThunks.lookup(I);
3138  if (!Thunk.isEmpty())
3139  dumpMicrosoftThunkAdjustment(Thunk, Out, /*ContinueFirstLine=*/false);
3140 
3141  break;
3142  }
3143 
3145  const CXXDestructorDecl *DD = Component.getDestructorDecl();
3146 
3147  DD->printQualifiedName(Out);
3148  Out << "() [scalar deleting]";
3149 
3150  if (DD->isPure())
3151  Out << " [pure]";
3152 
3153  ThunkInfo Thunk = VTableThunks.lookup(I);
3154  if (!Thunk.isEmpty()) {
3155  assert(Thunk.Return.isEmpty() &&
3156  "No return adjustment needed for destructors!");
3157  dumpMicrosoftThunkAdjustment(Thunk, Out, /*ContinueFirstLine=*/false);
3158  }
3159 
3160  break;
3161  }
3162 
3163  default:
3164  DiagnosticsEngine &Diags = Context.getDiagnostics();
3165  unsigned DiagID = Diags.getCustomDiagID(
3167  "Unexpected vftable component type %0 for component number %1");
3168  Diags.Report(MostDerivedClass->getLocation(), DiagID)
3169  << I << Component.getKind();
3170  }
3171 
3172  Out << '\n';
3173  }
3174 
3175  Out << '\n';
3176 
3177  if (!Thunks.empty()) {
3178  // We store the method names in a map to get a stable order.
3179  std::map<std::string, const CXXMethodDecl *> MethodNamesAndDecls;
3180 
3181  for (const auto &I : Thunks) {
3182  const CXXMethodDecl *MD = I.first;
3183  std::string MethodName = PredefinedExpr::ComputeName(
3185 
3186  MethodNamesAndDecls.insert(std::make_pair(MethodName, MD));
3187  }
3188 
3189  for (const auto &MethodNameAndDecl : MethodNamesAndDecls) {
3190  const std::string &MethodName = MethodNameAndDecl.first;
3191  const CXXMethodDecl *MD = MethodNameAndDecl.second;
3192 
3193  ThunkInfoVectorTy ThunksVector = Thunks[MD];
3194  std::stable_sort(ThunksVector.begin(), ThunksVector.end(),
3195  [](const ThunkInfo &LHS, const ThunkInfo &RHS) {
3196  // Keep different thunks with the same adjustments in the order they
3197  // were put into the vector.
3198  return std::tie(LHS.This, LHS.Return) < std::tie(RHS.This, RHS.Return);
3199  });
3200 
3201  Out << "Thunks for '" << MethodName << "' (" << ThunksVector.size();
3202  Out << (ThunksVector.size() == 1 ? " entry" : " entries") << ").\n";
3203 
3204  for (unsigned I = 0, E = ThunksVector.size(); I != E; ++I) {
3205  const ThunkInfo &Thunk = ThunksVector[I];
3206 
3207  Out << llvm::format("%4d | ", I);
3208  dumpMicrosoftThunkAdjustment(Thunk, Out, /*ContinueFirstLine=*/true);
3209  Out << '\n';
3210  }
3211 
3212  Out << '\n';
3213  }
3214  }
3215 
3216  Out.flush();
3217 }
3218 
3219 static bool setsIntersect(const llvm::SmallPtrSet<const CXXRecordDecl *, 4> &A,
3221  for (const CXXRecordDecl *Decl : B) {
3222  if (A.count(Decl))
3223  return true;
3224  }
3225  return false;
3226 }
3227 
3228 static bool rebucketPaths(VPtrInfoVector &Paths);
3229 
3230 /// Produces MSVC-compatible vbtable data. The symbols produced by this
3231 /// algorithm match those produced by MSVC 2012 and newer, which is different
3232 /// from MSVC 2010.
3233 ///
3234 /// MSVC 2012 appears to minimize the vbtable names using the following
3235 /// algorithm. First, walk the class hierarchy in the usual order, depth first,
3236 /// left to right, to find all of the subobjects which contain a vbptr field.
3237 /// Visiting each class node yields a list of inheritance paths to vbptrs. Each
3238 /// record with a vbptr creates an initially empty path.
3239 ///
3240 /// To combine paths from child nodes, the paths are compared to check for
3241 /// ambiguity. Paths are "ambiguous" if multiple paths have the same set of
3242 /// components in the same order. Each group of ambiguous paths is extended by
3243 /// appending the class of the base from which it came. If the current class
3244 /// node produced an ambiguous path, its path is extended with the current class.
3245 /// After extending paths, MSVC again checks for ambiguity, and extends any
3246 /// ambiguous path which wasn't already extended. Because each node yields an
3247 /// unambiguous set of paths, MSVC doesn't need to extend any path more than once
3248 /// to produce an unambiguous set of paths.
3249 ///
3250 /// TODO: Presumably vftables use the same algorithm.
3251 void MicrosoftVTableContext::computeVTablePaths(bool ForVBTables,
3252  const CXXRecordDecl *RD,
3253  VPtrInfoVector &Paths) {
3254  assert(Paths.empty());
3255  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3256 
3257  // Base case: this subobject has its own vptr.
3258  if (ForVBTables ? Layout.hasOwnVBPtr() : Layout.hasOwnVFPtr())
3259  Paths.push_back(llvm::make_unique<VPtrInfo>(RD));
3260 
3261  // Recursive case: get all the vbtables from our bases and remove anything
3262  // that shares a virtual base.
3263  llvm::SmallPtrSet<const CXXRecordDecl*, 4> VBasesSeen;
3264  for (const auto &B : RD->bases()) {
3265  const CXXRecordDecl *Base = B.getType()->getAsCXXRecordDecl();
3266  if (B.isVirtual() && VBasesSeen.count(Base))
3267  continue;
3268 
3269  if (!Base->isDynamicClass())
3270  continue;
3271 
3272  const VPtrInfoVector &BasePaths =
3273  ForVBTables ? enumerateVBTables(Base) : getVFPtrOffsets(Base);
3274 
3275  for (const std::unique_ptr<VPtrInfo> &BaseInfo : BasePaths) {
3276  // Don't include the path if it goes through a virtual base that we've
3277  // already included.
3278  if (setsIntersect(VBasesSeen, BaseInfo->ContainingVBases))
3279  continue;
3280 
3281  // Copy the path and adjust it as necessary.
3282  auto P = llvm::make_unique<VPtrInfo>(*BaseInfo);
3283 
3284  // We mangle Base into the path if the path would've been ambiguous and it
3285  // wasn't already extended with Base.
3286  if (P->MangledPath.empty() || P->MangledPath.back() != Base)
3287  P->NextBaseToMangle = Base;
3288 
3289  // Keep track of which vtable the derived class is going to extend with
3290  // new methods or bases. We append to either the vftable of our primary
3291  // base, or the first non-virtual base that has a vbtable.
3292  if (P->ObjectWithVPtr == Base &&
3293  Base == (ForVBTables ? Layout.getBaseSharingVBPtr()
3294  : Layout.getPrimaryBase()))
3295  P->ObjectWithVPtr = RD;
3296 
3297  // Keep track of the full adjustment from the MDC to this vtable. The
3298  // adjustment is captured by an optional vbase and a non-virtual offset.
3299  if (B.isVirtual())
3300  P->ContainingVBases.push_back(Base);
3301  else if (P->ContainingVBases.empty())
3302  P->NonVirtualOffset += Layout.getBaseClassOffset(Base);
3303 
3304  // Update the full offset in the MDC.
3305  P->FullOffsetInMDC = P->NonVirtualOffset;
3306  if (const CXXRecordDecl *VB = P->getVBaseWithVPtr())
3307  P->FullOffsetInMDC += Layout.getVBaseClassOffset(VB);
3308 
3309  Paths.push_back(std::move(P));
3310  }
3311 
3312  if (B.isVirtual())
3313  VBasesSeen.insert(Base);
3314 
3315  // After visiting any direct base, we've transitively visited all of its
3316  // morally virtual bases.
3317  for (const auto &VB : Base->vbases())
3318  VBasesSeen.insert(VB.getType()->getAsCXXRecordDecl());
3319  }
3320 
3321  // Sort the paths into buckets, and if any of them are ambiguous, extend all
3322  // paths in ambiguous buckets.
3323  bool Changed = true;
3324  while (Changed)
3325  Changed = rebucketPaths(Paths);
3326 }
3327 
3328 static bool extendPath(VPtrInfo &P) {
3329  if (P.NextBaseToMangle) {
3330  P.MangledPath.push_back(P.NextBaseToMangle);
3331  P.NextBaseToMangle = nullptr;// Prevent the path from being extended twice.
3332  return true;
3333  }
3334  return false;
3335 }
3336 
3337 static bool rebucketPaths(VPtrInfoVector &Paths) {
3338  // What we're essentially doing here is bucketing together ambiguous paths.
3339  // Any bucket with more than one path in it gets extended by NextBase, which
3340  // is usually the direct base of the inherited the vbptr. This code uses a
3341  // sorted vector to implement a multiset to form the buckets. Note that the
3342  // ordering is based on pointers, but it doesn't change our output order. The
3343  // current algorithm is designed to match MSVC 2012's names.
3345  PathsSorted.reserve(Paths.size());
3346  for (auto& P : Paths)
3347  PathsSorted.push_back(*P);
3348  llvm::sort(PathsSorted.begin(), PathsSorted.end(),
3349  [](const VPtrInfo &LHS, const VPtrInfo &RHS) {
3350  return LHS.MangledPath < RHS.MangledPath;
3351  });
3352  bool Changed = false;
3353  for (size_t I = 0, E = PathsSorted.size(); I != E;) {
3354  // Scan forward to find the end of the bucket.
3355  size_t BucketStart = I;
3356  do {
3357  ++I;
3358  } while (I != E &&
3359  PathsSorted[BucketStart].get().MangledPath ==
3360  PathsSorted[I].get().MangledPath);
3361 
3362  // If this bucket has multiple paths, extend them all.
3363  if (I - BucketStart > 1) {
3364  for (size_t II = BucketStart; II != I; ++II)
3365  Changed |= extendPath(PathsSorted[II]);
3366  assert(Changed && "no paths were extended to fix ambiguity");
3367  }
3368  }
3369  return Changed;
3370 }
3371 
3373 
3374 namespace {
3375 typedef llvm::SetVector<BaseSubobject, std::vector<BaseSubobject>,
3376  llvm::DenseSet<BaseSubobject>> FullPathTy;
3377 }
3378 
3379 // This recursive function finds all paths from a subobject centered at
3380 // (RD, Offset) to the subobject located at IntroducingObject.
3381 static void findPathsToSubobject(ASTContext &Context,
3382  const ASTRecordLayout &MostDerivedLayout,
3383  const CXXRecordDecl *RD, CharUnits Offset,
3384  BaseSubobject IntroducingObject,
3385  FullPathTy &FullPath,
3386  std::list<FullPathTy> &Paths) {
3387  if (BaseSubobject(RD, Offset) == IntroducingObject) {
3388  Paths.push_back(FullPath);
3389  return;
3390  }
3391 
3392  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3393 
3394  for (const CXXBaseSpecifier &BS : RD->bases()) {
3395  const CXXRecordDecl *Base = BS.getType()->getAsCXXRecordDecl();
3396  CharUnits NewOffset = BS.isVirtual()
3397  ? MostDerivedLayout.getVBaseClassOffset(Base)
3398  : Offset + Layout.getBaseClassOffset(Base);
3399  FullPath.insert(BaseSubobject(Base, NewOffset));
3400  findPathsToSubobject(Context, MostDerivedLayout, Base, NewOffset,
3401  IntroducingObject, FullPath, Paths);
3402  FullPath.pop_back();
3403  }
3404 }
3405 
3406 // Return the paths which are not subsets of other paths.
3407 static void removeRedundantPaths(std::list<FullPathTy> &FullPaths) {
3408  FullPaths.remove_if([&](const FullPathTy &SpecificPath) {
3409  for (const FullPathTy &OtherPath : FullPaths) {
3410  if (&SpecificPath == &OtherPath)
3411  continue;
3412  if (std::all_of(SpecificPath.begin(), SpecificPath.end(),
3413  [&](const BaseSubobject &BSO) {
3414  return OtherPath.count(BSO) != 0;
3415  })) {
3416  return true;
3417  }
3418  }
3419  return false;
3420  });
3421 }
3422 
3424  const CXXRecordDecl *RD,
3425  const FullPathTy &FullPath) {
3426  const ASTRecordLayout &MostDerivedLayout =
3427  Context.getASTRecordLayout(RD);
3429  for (const BaseSubobject &BSO : FullPath) {
3430  const CXXRecordDecl *Base = BSO.getBase();
3431  // The first entry in the path is always the most derived record, skip it.
3432  if (Base == RD) {
3433  assert(Offset.getQuantity() == -1);
3434  Offset = CharUnits::Zero();
3435  continue;
3436  }
3437  assert(Offset.getQuantity() != -1);
3438  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3439  // While we know which base has to be traversed, we don't know if that base
3440  // was a virtual base.
3441  const CXXBaseSpecifier *BaseBS = std::find_if(
3442  RD->bases_begin(), RD->bases_end(), [&](const CXXBaseSpecifier &BS) {
3443  return BS.getType()->getAsCXXRecordDecl() == Base;
3444  });
3445  Offset = BaseBS->isVirtual() ? MostDerivedLayout.getVBaseClassOffset(Base)
3446  : Offset + Layout.getBaseClassOffset(Base);
3447  RD = Base;
3448  }
3449  return Offset;
3450 }
3451 
3452 // We want to select the path which introduces the most covariant overrides. If
3453 // two paths introduce overrides which the other path doesn't contain, issue a
3454 // diagnostic.
3455 static const FullPathTy *selectBestPath(ASTContext &Context,
3456  const CXXRecordDecl *RD,
3457  const VPtrInfo &Info,
3458  std::list<FullPathTy> &FullPaths) {
3459  // Handle some easy cases first.
3460  if (FullPaths.empty())
3461  return nullptr;
3462  if (FullPaths.size() == 1)
3463  return &FullPaths.front();
3464 
3465  const FullPathTy *BestPath = nullptr;
3466  typedef std::set<const CXXMethodDecl *> OverriderSetTy;
3467  OverriderSetTy LastOverrides;
3468  for (const FullPathTy &SpecificPath : FullPaths) {
3469  assert(!SpecificPath.empty());
3470  OverriderSetTy CurrentOverrides;
3471  const CXXRecordDecl *TopLevelRD = SpecificPath.begin()->getBase();
3472  // Find the distance from the start of the path to the subobject with the
3473  // VPtr.
3474  CharUnits BaseOffset =
3475  getOffsetOfFullPath(Context, TopLevelRD, SpecificPath);
3476  FinalOverriders Overriders(TopLevelRD, CharUnits::Zero(), TopLevelRD);
3477  for (const CXXMethodDecl *MD : Info.IntroducingObject->methods()) {
3478  if (!MD->isVirtual())
3479  continue;
3480  FinalOverriders::OverriderInfo OI =
3481  Overriders.getOverrider(MD->getCanonicalDecl(), BaseOffset);
3482  const CXXMethodDecl *OverridingMethod = OI.Method;
3483  // Only overriders which have a return adjustment introduce problematic
3484  // thunks.
3485  if (ComputeReturnAdjustmentBaseOffset(Context, OverridingMethod, MD)
3486  .isEmpty())
3487  continue;
3488  // It's possible that the overrider isn't in this path. If so, skip it
3489  // because this path didn't introduce it.
3490  const CXXRecordDecl *OverridingParent = OverridingMethod->getParent();
3491  if (std::none_of(SpecificPath.begin(), SpecificPath.end(),
3492  [&](const BaseSubobject &BSO) {
3493  return BSO.getBase() == OverridingParent;
3494  }))
3495  continue;
3496  CurrentOverrides.insert(OverridingMethod);
3497  }
3498  OverriderSetTy NewOverrides =
3499  llvm::set_difference(CurrentOverrides, LastOverrides);
3500  if (NewOverrides.empty())
3501  continue;
3502  OverriderSetTy MissingOverrides =
3503  llvm::set_difference(LastOverrides, CurrentOverrides);
3504  if (MissingOverrides.empty()) {
3505  // This path is a strict improvement over the last path, let's use it.
3506  BestPath = &SpecificPath;
3507  std::swap(CurrentOverrides, LastOverrides);
3508  } else {
3509  // This path introduces an overrider with a conflicting covariant thunk.
3510  DiagnosticsEngine &Diags = Context.getDiagnostics();
3511  const CXXMethodDecl *CovariantMD = *NewOverrides.begin();
3512  const CXXMethodDecl *ConflictMD = *MissingOverrides.begin();
3513  Diags.Report(RD->getLocation(), diag::err_vftable_ambiguous_component)
3514  << RD;
3515  Diags.Report(CovariantMD->getLocation(), diag::note_covariant_thunk)
3516  << CovariantMD;
3517  Diags.Report(ConflictMD->getLocation(), diag::note_covariant_thunk)
3518  << ConflictMD;
3519  }
3520  }
3521  // Go with the path that introduced the most covariant overrides. If there is
3522  // no such path, pick the first path.
3523  return BestPath ? BestPath : &FullPaths.front();
3524 }
3525 
3527  const CXXRecordDecl *RD,
3528  VPtrInfoVector &Paths) {
3529  const ASTRecordLayout &MostDerivedLayout = Context.getASTRecordLayout(RD);
3530  FullPathTy FullPath;
3531  std::list<FullPathTy> FullPaths;
3532  for (const std::unique_ptr<VPtrInfo>& Info : Paths) {
3534  Context, MostDerivedLayout, RD, CharUnits::Zero(),
3535  BaseSubobject(Info->IntroducingObject, Info->FullOffsetInMDC), FullPath,
3536  FullPaths);
3537  FullPath.clear();
3538  removeRedundantPaths(FullPaths);
3539  Info->PathToIntroducingObject.clear();
3540  if (const FullPathTy *BestPath =
3541  selectBestPath(Context, RD, *Info, FullPaths))
3542  for (const BaseSubobject &BSO : *BestPath)
3543  Info->PathToIntroducingObject.push_back(BSO.getBase());
3544  FullPaths.clear();
3545  }
3546 }
3547 
3548 static bool vfptrIsEarlierInMDC(const ASTRecordLayout &Layout,
3549  const MethodVFTableLocation &LHS,
3550  const MethodVFTableLocation &RHS) {
3551  CharUnits L = LHS.VFPtrOffset;
3552  CharUnits R = RHS.VFPtrOffset;
3553  if (LHS.VBase)
3554  L += Layout.getVBaseClassOffset(LHS.VBase);
3555  if (RHS.VBase)
3556  R += Layout.getVBaseClassOffset(RHS.VBase);
3557  return L < R;
3558 }
3559 
3560 void MicrosoftVTableContext::computeVTableRelatedInformation(
3561  const CXXRecordDecl *RD) {
3562  assert(RD->isDynamicClass());
3563 
3564  // Check if we've computed this information before.
3565  if (VFPtrLocations.count(RD))
3566  return;
3567 
3568  const VTableLayout::AddressPointsMapTy EmptyAddressPointsMap;
3569 
3570  {
3571  auto VFPtrs = llvm::make_unique<VPtrInfoVector>();
3572  computeVTablePaths(/*ForVBTables=*/false, RD, *VFPtrs);
3573  computeFullPathsForVFTables(Context, RD, *VFPtrs);
3574  VFPtrLocations[RD] = std::move(VFPtrs);
3575  }
3576 
3577  MethodVFTableLocationsTy NewMethodLocations;
3578  for (const std::unique_ptr<VPtrInfo> &VFPtr : *VFPtrLocations[RD]) {
3579  VFTableBuilder Builder(*this, RD, *VFPtr);
3580 
3581  VFTableIdTy id(RD, VFPtr->FullOffsetInMDC);
3582  assert(VFTableLayouts.count(id) == 0);
3584  Builder.vtable_thunks_begin(), Builder.vtable_thunks_end());
3585  VFTableLayouts[id] = llvm::make_unique<VTableLayout>(
3586  ArrayRef<size_t>{0}, Builder.vtable_components(), VTableThunks,
3587  EmptyAddressPointsMap);
3588  Thunks.insert(Builder.thunks_begin(), Builder.thunks_end());
3589 
3590  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3591  for (const auto &Loc : Builder.vtable_locations()) {
3592  auto Insert = NewMethodLocations.insert(Loc);
3593  if (!Insert.second) {
3594  const MethodVFTableLocation &NewLoc = Loc.second;
3595  MethodVFTableLocation &OldLoc = Insert.first->second;
3596  if (vfptrIsEarlierInMDC(Layout, NewLoc, OldLoc))
3597  OldLoc = NewLoc;
3598  }
3599  }
3600  }
3601 
3602  MethodVFTableLocations.insert(NewMethodLocations.begin(),
3603  NewMethodLocations.end());
3604  if (Context.getLangOpts().DumpVTableLayouts)
3605  dumpMethodLocations(RD, NewMethodLocations, llvm::outs());
3606 }
3607 
3608 void MicrosoftVTableContext::dumpMethodLocations(
3609  const CXXRecordDecl *RD, const MethodVFTableLocationsTy &NewMethods,
3610  raw_ostream &Out) {
3611  // Compute the vtable indices for all the member functions.
3612  // Store them in a map keyed by the location so we'll get a sorted table.
3613  std::map<MethodVFTableLocation, std::string> IndicesMap;
3614  bool HasNonzeroOffset = false;
3615 
3616  for (const auto &I : NewMethods) {
3617  const CXXMethodDecl *MD = cast<const CXXMethodDecl>(I.first.getDecl());
3618  assert(MD->isVirtual());
3619 
3620  std::string MethodName = PredefinedExpr::ComputeName(
3622 
3623  if (isa<CXXDestructorDecl>(MD)) {
3624  IndicesMap[I.second] = MethodName + " [scalar deleting]";
3625  } else {
3626  IndicesMap[I.second] = MethodName;
3627  }
3628 
3629  if (!I.second.VFPtrOffset.isZero() || I.second.VBTableIndex != 0)
3630  HasNonzeroOffset = true;
3631  }
3632 
3633  // Print the vtable indices for all the member functions.
3634  if (!IndicesMap.empty()) {
3635  Out << "VFTable indices for ";
3636  Out << "'";
3637  RD->printQualifiedName(Out);
3638  Out << "' (" << IndicesMap.size()
3639  << (IndicesMap.size() == 1 ? " entry" : " entries") << ").\n";
3640 
3641  CharUnits LastVFPtrOffset = CharUnits::fromQuantity(-1);
3642  uint64_t LastVBIndex = 0;
3643  for (const auto &I : IndicesMap) {
3644  CharUnits VFPtrOffset = I.first.VFPtrOffset;
3645  uint64_t VBIndex = I.first.VBTableIndex;
3646  if (HasNonzeroOffset &&
3647  (VFPtrOffset != LastVFPtrOffset || VBIndex != LastVBIndex)) {
3648  assert(VBIndex > LastVBIndex || VFPtrOffset > LastVFPtrOffset);
3649  Out << " -- accessible via ";
3650  if (VBIndex)
3651  Out << "vbtable index " << VBIndex << ", ";
3652  Out << "vfptr at offset " << VFPtrOffset.getQuantity() << " --\n";
3653  LastVFPtrOffset = VFPtrOffset;
3654  LastVBIndex = VBIndex;
3655  }
3656 
3657  uint64_t VTableIndex = I.first.Index;
3658  const std::string &MethodName = I.second;
3659  Out << llvm::format("%4" PRIu64 " | ", VTableIndex) << MethodName << '\n';
3660  }
3661  Out << '\n';
3662  }
3663 
3664  Out.flush();
3665 }
3666 
3667 const VirtualBaseInfo &MicrosoftVTableContext::computeVBTableRelatedInformation(
3668  const CXXRecordDecl *RD) {
3669  VirtualBaseInfo *VBI;
3670 
3671  {
3672  // Get or create a VBI for RD. Don't hold a reference to the DenseMap cell,
3673  // as it may be modified and rehashed under us.
3674  std::unique_ptr<VirtualBaseInfo> &Entry = VBaseInfo[RD];
3675  if (Entry)
3676  return *Entry;
3677  Entry = llvm::make_unique<VirtualBaseInfo>();
3678  VBI = Entry.get();
3679  }
3680 
3681  computeVTablePaths(/*ForVBTables=*/true, RD, VBI->VBPtrPaths);
3682 
3683  // First, see if the Derived class shared the vbptr with a non-virtual base.
3684  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3685  if (const CXXRecordDecl *VBPtrBase = Layout.getBaseSharingVBPtr()) {
3686  // If the Derived class shares the vbptr with a non-virtual base, the shared
3687  // virtual bases come first so that the layout is the same.
3688  const VirtualBaseInfo &BaseInfo =
3689  computeVBTableRelatedInformation(VBPtrBase);
3690  VBI->VBTableIndices.insert(BaseInfo.VBTableIndices.begin(),
3691  BaseInfo.VBTableIndices.end());
3692  }
3693 
3694  // New vbases are added to the end of the vbtable.
3695  // Skip the self entry and vbases visited in the non-virtual base, if any.
3696  unsigned VBTableIndex = 1 + VBI->VBTableIndices.size();
3697  for (const auto &VB : RD->vbases()) {
3698  const CXXRecordDecl *CurVBase = VB.getType()->getAsCXXRecordDecl();
3699  if (!VBI->VBTableIndices.count(CurVBase))
3700  VBI->VBTableIndices[CurVBase] = VBTableIndex++;
3701  }
3702 
3703  return *VBI;
3704 }
3705 
3707  const CXXRecordDecl *VBase) {
3708  const VirtualBaseInfo &VBInfo = computeVBTableRelatedInformation(Derived);
3709  assert(VBInfo.VBTableIndices.count(VBase));
3710  return VBInfo.VBTableIndices.find(VBase)->second;
3711 }
3712 
3713 const VPtrInfoVector &
3715  return computeVBTableRelatedInformation(RD).VBPtrPaths;
3716 }
3717 
3718 const VPtrInfoVector &
3720  computeVTableRelatedInformation(RD);
3721 
3722  assert(VFPtrLocations.count(RD) && "Couldn't find vfptr locations");
3723  return *VFPtrLocations[RD];
3724 }
3725 
3726 const VTableLayout &
3728  CharUnits VFPtrOffset) {
3729  computeVTableRelatedInformation(RD);
3730 
3731  VFTableIdTy id(RD, VFPtrOffset);
3732  assert(VFTableLayouts.count(id) && "Couldn't find a VFTable at this offset");
3733  return *VFTableLayouts[id];
3734 }
3735 
3738  assert(cast<CXXMethodDecl>(GD.getDecl())->isVirtual() &&
3739  "Only use this method for virtual methods or dtors");
3740  if (isa<CXXDestructorDecl>(GD.getDecl()))
3741  assert(GD.getDtorType() == Dtor_Deleting);
3742 
3743  GD = GD.getCanonicalDecl();
3744 
3745  MethodVFTableLocationsTy::iterator I = MethodVFTableLocations.find(GD);
3746  if (I != MethodVFTableLocations.end())
3747  return I->second;
3748 
3749  const CXXRecordDecl *RD = cast<CXXMethodDecl>(GD.getDecl())->getParent();
3750 
3751  computeVTableRelatedInformation(RD);
3752 
3753  I = MethodVFTableLocations.find(GD);
3754  assert(I != MethodVFTableLocations.end() && "Did not find index!");
3755  return I->second;
3756 }
Defines the clang::ASTContext interface.
static std::string ComputeName(IdentType IT, const Decl *CurrentDecl)
Definition: Expr.cpp:495
if(T->getSizeExpr()) TRY_TO(TraverseStmt(T -> getSizeExpr()))
PointerType - C99 6.7.5.1 - Pointer Declarators.
Definition: Type.h:2375
bool isPrimaryBaseVirtual() const
isPrimaryBaseVirtual - Get whether the primary base for this record is virtual or not...
Definition: RecordLayout.h:216
A (possibly-)qualified type.
Definition: Type.h:655
base_class_range bases()
Definition: DeclCXX.h:811
uint32_t VBPtrOffset
The offset (in bytes) of the vbptr, relative to the beginning of the derived class.
Definition: ABI.h:61
bool isEmpty() const
Definition: ABI.h:155
CXXDtorType getDtorType() const
Definition: GlobalDecl.h:71
ItaniumVTableContext(ASTContext &Context)
static VTableComponent MakeRTTI(const CXXRecordDecl *RD)
Definition: VTableBuilder.h:67
const CXXMethodDecl * getFunctionDecl() const
const ASTRecordLayout & getASTRecordLayout(const RecordDecl *D) const
Get or compute information about the layout of the specified record (struct/union/class) D...
FunctionType - C99 6.7.5.3 - Function Declarators.
Definition: Type.h:3148
CharUnits getBaseClassOffset(const CXXRecordDecl *Base) const
getBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:223
unsigned getNumVBases() const
Retrieves the number of virtual base classes of this class.
Definition: DeclCXX.h:826
VPtrInfoVector VBPtrPaths
Information on all virtual base tables used when this record is the most derived class.
bool isEmpty() const
Definition: ABI.h:87
Decl - This represents one declaration (or definition), e.g.
Definition: DeclBase.h:86
CharUnits VFPtrOffset
This is the offset of the vfptr from the start of the last vbase, or the complete type if there are n...
bool isVirtual() const
Definition: DeclCXX.h:2076
bool isVirtual() const
Determines whether the base class is a virtual base class (or not).
Definition: DeclCXX.h:245
StringRef P
GlobalDecl getCanonicalDecl() const
Definition: GlobalDecl.h:56
int64_t NonVirtual
The non-virtual adjustment from the derived object to its nearest virtual base.
Definition: ABI.h:111
CanQual< T > getUnqualifiedType() const
Retrieve the unqualified form of this type.
DiagnosticsEngine & getDiagnostics() const
bool isDerivedFrom(const CXXRecordDecl *Base) const
Determine whether this class is derived from the class Base.
DiagnosticBuilder Report(SourceLocation Loc, unsigned DiagID)
Issue the message to the client.
Definition: Diagnostic.h:1294
bool isZero() const
isZero - Test whether the quantity equals zero.
Definition: CharUnits.h:116
const TargetInfo & getTargetInfo() const
Definition: ASTContext.h:672
const NestedNameSpecifier * Specifier
BasePath MangledPath
The bases from the inheritance path that got used to mangle the vbtable name.
Represents a path from a specific derived class (which is not represented as part of the path) to a p...
static std::unique_ptr< VTableLayout > CreateVTableLayout(const ItaniumVTableBuilder &Builder)
static VTableComponent MakeUnusedFunction(const CXXMethodDecl *MD)
Definition: VTableBuilder.h:89
const CXXMethodDecl * getUnusedFunctionDecl() const
QualType getReturnType() const
Definition: Decl.h:2262
const CXXRecordDecl * VBase
If nonnull, holds the last vbase which contains the vfptr that the method definition is adjusted to...
const T * getAs() const
Member-template getAs<specific type>&#39;.
Definition: Type.h:6456
decl_range decls() const
decls_begin/decls_end - Iterate over the declarations stored in this context.
Definition: DeclBase.h:1586
static VTableComponent MakeVCallOffset(CharUnits Offset)
Definition: VTableBuilder.h:55
A this pointer adjustment.
Definition: ABI.h:108
const CXXMethodDecl * Method
Holds a pointer to the overridden method this thunk is for, if needed by the ABI to distinguish diffe...
Definition: ABI.h:191
CharUnits getBaseOffset() const
getBaseOffset - Returns the base class offset.
Definition: BaseSubobject.h:46
uint64_t getPointerWidth(unsigned AddrSpace) const
Return the width of pointers on this target, for the specified address space.
Definition: TargetInfo.h:339
int32_t VBOffsetOffset
The offset (in bytes) of the vbase offset in the vbtable.
Definition: ABI.h:132
DeclarationName getDeclName() const
Get the actual, stored name of the declaration, which may be a special name.
Definition: Decl.h:297
TargetCXXABI getCXXABI() const
Get the C++ ABI currently in use.
Definition: TargetInfo.h:1004
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:150
ArrayRef< QualType > getParamTypes() const
Definition: Type.h:3612
CXXMethodDecl * getCanonicalDecl() override
Retrieves the "canonical" declaration of the given declaration.
Definition: DeclCXX.h:2112
static VTableComponent MakeCompleteDtor(const CXXDestructorDecl *DD)
Definition: VTableBuilder.h:79
A return adjustment.
Definition: ABI.h:42
static CharUnits Zero()
Zero - Construct a CharUnits quantity of zero.
Definition: CharUnits.h:53
llvm::DenseMap< const CXXRecordDecl *, unsigned > VBTableIndices
A map from virtual base to vbtable index for doing a conversion from the the derived class to the a b...
CharUnits getVBaseClassOffset(const CXXRecordDecl *VBase) const
getVBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:231
The this pointer adjustment as well as an optional return adjustment for a thunk. ...
Definition: ABI.h:179
const CXXRecordDecl * NextBaseToMangle
The next base to push onto the mangled path if this path is ambiguous in a derived class...
unsigned getTypeQuals() const
Definition: Type.h:3723
The set of methods that override a given virtual method in each subobject where it occurs...
CharUnits - This is an opaque type for sizes expressed in character units.
Definition: CharUnits.h:38
llvm::DenseMap< const CXXMethodDecl *, ThunkInfoVectorTy > ThunksMapTy
uint32_t Offset
Definition: CacheTokens.cpp:43
static void dump(llvm::raw_ostream &OS, StringRef FunctionName, ArrayRef< CounterExpression > Expressions, ArrayRef< CounterMappingRegion > Regions)
struct clang::ReturnAdjustment::VirtualAdjustment::@117 Itanium
const CXXRecordDecl * IntroducingObject
This is the class that introduced the vptr by declaring new virtual methods or virtual bases...
Deleting dtor.
Definition: ABI.h:35
Concrete class used by the front-end to report problems and issues.
Definition: Diagnostic.h:149
const VPtrInfoVector & getVFPtrOffsets(const CXXRecordDecl *RD)
base_class_iterator bases_begin()
Definition: DeclCXX.h:818
static void removeRedundantPaths(std::list< FullPathTy > &FullPaths)
uint64_t getMethodVTableIndex(GlobalDecl GD)
Locate a virtual function in the vtable.
CharUnits getVirtualBaseOffsetOffset(const CXXRecordDecl *RD, const CXXRecordDecl *VBase)
Return the offset in chars (relative to the vtable address point) where the offset of the virtual bas...
static bool setsIntersect(const llvm::SmallPtrSet< const CXXRecordDecl *, 4 > &A, ArrayRef< const CXXRecordDecl *> B)
static VTableComponent MakeDeletingDtor(const CXXDestructorDecl *DD)
Definition: VTableBuilder.h:84
CXXRecordDecl * getAsCXXRecordDecl() const
Retrieves the CXXRecordDecl that this type refers to, either because the type is a RecordType or beca...
Definition: Type.cpp:1590
Represents a prototype with parameter type info, e.g.
Definition: Type.h:3369
bool isDynamicClass() const
Definition: DeclCXX.h:789
union clang::ReturnAdjustment::VirtualAdjustment Virtual
QuantityType getQuantity() const
getQuantity - Get the raw integer representation of this quantity.
Definition: CharUnits.h:179
ASTRecordLayout - This class contains layout information for one RecordDecl, which is a struct/union/...
Definition: RecordLayout.h:39
static void GroupNewVirtualOverloads(const CXXRecordDecl *RD, SmallVector< const CXXMethodDecl *, 10 > &VirtualMethods)
SmallVector< ThunkInfo, 1 > ThunkInfoVectorTy
const FunctionProtoType * T
Kind getKind() const
Get the kind of this vtable component.
Definition: VTableBuilder.h:97
void getFinalOverriders(CXXFinalOverriderMap &FinaOverriders) const
Retrieve the final overriders for each virtual member function in the class hierarchy where this clas...
Represents a C++ destructor within a class.
Definition: DeclCXX.h:2686
bool isImplicit() const
isImplicit - Indicates whether the declaration was implicitly generated by the implementation.
Definition: DeclBase.h:552
overridden_method_range overridden_methods() const
Definition: DeclCXX.cpp:2132
CharUnits getOffsetToTop() const
CharUnits getVCallOffset() const
const CXXRecordDecl * getPrimaryBase() const
getPrimaryBase - Get the primary base for this record.
Definition: RecordLayout.h:208
static CharUnits fromQuantity(QuantityType Quantity)
fromQuantity - Construct a CharUnits quantity from a raw integer type.
Definition: CharUnits.h:63
internal::Matcher< T > id(StringRef ID, const internal::BindableMatcher< T > &InnerMatcher)
If the provided matcher matches a node, binds the node to ID.
Definition: ASTMatchers.h:137
static void findPathsToSubobject(ASTContext &Context, const ASTRecordLayout &MostDerivedLayout, const CXXRecordDecl *RD, CharUnits Offset, BaseSubobject IntroducingObject, FullPathTy &FullPath, std::list< FullPathTy > &Paths)
const CXXRecordDecl * getBase() const
getBase - Returns the base class declaration.
Definition: BaseSubobject.h:43
bool isPolymorphic() const
Whether this class is polymorphic (C++ [class.virtual]), which means that the class contains or inher...
Definition: DeclCXX.h:1327
DeclContext * getParent()
getParent - Returns the containing DeclContext.
Definition: DeclBase.h:1341
const CXXDestructorDecl * getDestructorDecl() const
Uniquely identifies a virtual method within a class hierarchy by the method itself and a class subobj...
CharUnits getVBPtrOffset() const
getVBPtrOffset - Get the offset for virtual base table pointer.
Definition: RecordLayout.h:296
struct clang::ReturnAdjustment::VirtualAdjustment::@118 Microsoft
void printQualifiedName(raw_ostream &OS) const
Returns a human-readable qualified name for this declaration, like A::B::i, for i being member of nam...
Definition: Decl.cpp:1507
GlobalDecl - represents a global declaration.
Definition: GlobalDecl.h:35
static void PrintBasePath(const VPtrInfo::BasePath &Path, raw_ostream &Out)
int64_t NonVirtual
The non-virtual adjustment from the derived object to its nearest virtual base.
Definition: ABI.h:45
unsigned getVBTableIndex(const CXXRecordDecl *Derived, const CXXRecordDecl *VBase)
Returns the index of VBase in the vbtable of Derived.
const CXXBaseSpecifier * Base
The base specifier that states the link from a derived class to a base class, which will be followed ...
#define false
Definition: stdbool.h:33
QualType getCanonicalType() const
Definition: Type.h:5864
static bool rebucketPaths(VPtrInfoVector &Paths)
std::unique_ptr< VTableLayout > createConstructionVTableLayout(const CXXRecordDecl *MostDerivedClass, CharUnits MostDerivedClassOffset, bool MostDerivedClassIsVirtual, const CXXRecordDecl *LayoutClass)
QualType getReturnType() const
Definition: Type.h:3302
bool isPure() const
Whether this virtual function is pure, i.e.
Definition: Decl.h:2039
static void dumpMicrosoftThunkAdjustment(const ThunkInfo &TI, raw_ostream &Out, bool ContinueFirstLine)
ASTContext & getASTContext() const LLVM_READONLY
Definition: DeclBase.cpp:376
static bool vfptrIsEarlierInMDC(const ASTRecordLayout &Layout, const MethodVFTableLocation &LHS, const MethodVFTableLocation &RHS)
const Decl * getDecl() const
Definition: GlobalDecl.h:64
Represents a single component in a vtable.
Definition: VTableBuilder.h:30
Represents a static or instance method of a struct/union/class.
Definition: DeclCXX.h:2031
const VTableLayout & getVFTableLayout(const CXXRecordDecl *RD, CharUnits VFPtrOffset)
unsigned getCustomDiagID(Level L, const char(&FormatString)[N])
Return an ID for a diagnostic with the specified format string and level.
Definition: Diagnostic.h:775
int64_t VCallOffsetOffset
The offset (in bytes), relative to the address point, of the virtual call offset. ...
Definition: ABI.h:120
Complete object dtor.
Definition: ABI.h:36
const CXXRecordDecl * getRTTIDecl() const
CanProxy< U > getAs() const
Retrieve a canonical type pointer with a different static type, upcasting or downcasting as needed...
static VTableComponent MakeVBaseOffset(CharUnits Offset)
Definition: VTableBuilder.h:59
Represents an element in a path from a derived class to a base class.
struct clang::ThisAdjustment::VirtualAdjustment::@120 Microsoft
Dataflow Directional Tag Classes.
ThisAdjustment This
The this pointer adjustment.
Definition: ABI.h:181
const VPtrInfoVector & enumerateVBTables(const CXXRecordDecl *RD)
static bool isDirectVBase(const CXXRecordDecl *Base, const CXXRecordDecl *RD)
ThunksMapTy Thunks
Contains all thunks that a given method decl will need.
static bool extendPath(VPtrInfo &P)
The same as PrettyFunction, except that the &#39;virtual&#39; keyword is omitted for virtual member functions...
Definition: Expr.h:1215
DeclarationName - The name of a declaration.
static std::string getAsString(SplitQualType split, const PrintingPolicy &Policy)
Definition: Type.h:981
const CXXRecordDecl * getParent() const
Returns the parent of this method declaration, which is the class in which this method is defined...
Definition: DeclCXX.h:2151
const CXXRecordDecl * getBaseSharingVBPtr() const
Definition: RecordLayout.h:301
A mapping from each virtual member function to its set of final overriders.
static CharUnits getOffsetOfFullPath(ASTContext &Context, const CXXRecordDecl *RD, const FullPathTy &FullPath)
int64_t VBaseOffsetOffset
The offset (in bytes), relative to the address point of the virtual base class offset.
Definition: ABI.h:54
struct clang::ThisAdjustment::VirtualAdjustment::@119 Itanium
CharUnits NonVirtualOffset
IntroducingObject is at this offset from its containing complete object or virtual base...
base_class_iterator vbases_begin()
Definition: DeclCXX.h:835
bool isEmpty() const
Definition: ABI.h:204
All virtual base related information about a given record decl.
union clang::ThisAdjustment::VirtualAdjustment Virtual
VTableLayout(ArrayRef< size_t > VTableIndices, ArrayRef< VTableComponent > VTableComponents, ArrayRef< VTableThunkTy > VTableThunks, const AddressPointsMapTy &AddressPoints)
const CXXRecordDecl * getVBaseWithVPtr() const
The vptr is stored inside the non-virtual component of this virtual base.
CXXBasePath & front()
static const FullPathTy * selectBestPath(ASTContext &Context, const CXXRecordDecl *RD, const VPtrInfo &Info, std::list< FullPathTy > &FullPaths)
Base for LValueReferenceType and RValueReferenceType.
Definition: Type.h:2511
ReturnAdjustment Return
The return adjustment.
Definition: ABI.h:184
Represents a base class of a C++ class.
Definition: DeclCXX.h:192
CanQualType getCanonicalType(QualType T) const
Return the canonical (structural) type corresponding to the specified potentially non-canonical type ...
Definition: ASTContext.h:2207
CharUnits toCharUnitsFromBits(int64_t BitSize) const
Convert a size in bits to a size in characters.
llvm::DenseMap< BaseSubobject, AddressPointLocation > AddressPointsMapTy
Represents a C++ struct/union/class.
Definition: DeclCXX.h:300
int32_t VtordispOffset
The offset of the vtordisp (in bytes), relative to the ECX.
Definition: ABI.h:125
base_class_iterator bases_end()
Definition: DeclCXX.h:820
std::pair< uint64_t, ThunkInfo > VTableThunkTy
llvm::DenseMap< const CXXRecordDecl *, VBaseInfo > VBaseOffsetsMapTy
Definition: RecordLayout.h:60
Defines the clang::TargetInfo interface.
bool isMicrosoft() const
Is this ABI an MSVC-compatible ABI?
Definition: TargetCXXABI.h:154
A pointer to the deleting destructor.
Definition: VTableBuilder.h:43
static Decl::Kind getKind(const Decl *D)
Definition: DeclBase.cpp:930
CanQualType IntTy
Definition: ASTContext.h:1006
MethodVFTableLocation getMethodVFTableLocation(GlobalDecl GD)
static VTableComponent MakeFunction(const CXXMethodDecl *MD)
Definition: VTableBuilder.h:71
bool isDeleted() const
Whether this function has been deleted.
Definition: Decl.h:2123
Holds information about the inheritance path to a virtual base or function table pointer.
BasePaths - Represents the set of paths from a derived class to one of its (direct or indirect) bases...
CharUnits getTypeSizeInChars(QualType T) const
Return the size of the specified (complete) type T, in characters.
QualType getType() const
Definition: Decl.h:647
uint32_t VBIndex
Index of the virtual base in the vbtable.
Definition: ABI.h:64
This represents a decl that may have a name.
Definition: Decl.h:248
CharUnits getVBaseOffset() const
static void computeFullPathsForVFTables(ASTContext &Context, const CXXRecordDecl *RD, VPtrInfoVector &Paths)
const CXXRecordDecl * Class
The record decl of the class that the base is a base of.
int32_t VBPtrOffset
The offset of the vbptr of the derived class (in bytes), relative to the ECX after vtordisp adjustmen...
Definition: ABI.h:129
const LangOptions & getLangOpts() const
Definition: ASTContext.h:689
base_class_range vbases()
Definition: DeclCXX.h:828
A pointer to the complete destructor.
Definition: VTableBuilder.h:40
SourceLocation getLocation() const
Definition: DeclBase.h:417
method_range methods() const
Definition: DeclCXX.h:853
QualType getType() const
Retrieves the type of the base class.
Definition: DeclCXX.h:291
static VTableComponent MakeOffsetToTop(CharUnits Offset)
Definition: VTableBuilder.h:63