clang  15.0.0git
VTableBuilder.cpp
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1 //===--- VTableBuilder.cpp - C++ vtable layout builder --------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This contains code dealing with generation of the layout of virtual tables.
10 //
11 //===----------------------------------------------------------------------===//
12 
14 #include "clang/AST/ASTContext.h"
17 #include "clang/AST/RecordLayout.h"
18 #include "clang/Basic/TargetInfo.h"
19 #include "llvm/ADT/SetOperations.h"
20 #include "llvm/ADT/SetVector.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 auto *BaseFT = BaseMD->getType()->castAs<FunctionType>();
275  const auto *DerivedFT = DerivedMD->getType()->castAs<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()) {
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->getMethodQuals() != RT->getMethodQuals())
484  return false;
485  return LT->getParamTypes() == RT->getParamTypes();
486 }
487 
488 bool VCallOffsetMap::MethodsCanShareVCallOffset(const CXXMethodDecl *LHS,
489  const CXXMethodDecl *RHS) {
490  assert(VTableContextBase::hasVtableSlot(LHS) && "LHS must be virtual!");
491  assert(VTableContextBase::hasVtableSlot(RHS) && "RHS 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  const ItaniumVTableContext &VTables;
540 
541  /// MostDerivedClass - The most derived class for which we're building vcall
542  /// and vbase offsets.
543  const CXXRecordDecl *MostDerivedClass;
544 
545  /// LayoutClass - The class we're using for layout information. Will be
546  /// different than the most derived class if we're building a construction
547  /// vtable.
548  const CXXRecordDecl *LayoutClass;
549 
550  /// Context - The ASTContext which we will use for layout information.
551  ASTContext &Context;
552 
553  /// Components - vcall and vbase offset components
554  typedef SmallVector<VTableComponent, 64> VTableComponentVectorTy;
555  VTableComponentVectorTy Components;
556 
557  /// VisitedVirtualBases - Visited virtual bases.
559 
560  /// VCallOffsets - Keeps track of vcall offsets.
561  VCallOffsetMap VCallOffsets;
562 
563 
564  /// VBaseOffsetOffsets - Contains the offsets of the virtual base offsets,
565  /// relative to the address point.
566  VBaseOffsetOffsetsMapTy VBaseOffsetOffsets;
567 
568  /// FinalOverriders - The final overriders of the most derived class.
569  /// (Can be null when we're not building a vtable of the most derived class).
570  const FinalOverriders *Overriders;
571 
572  /// AddVCallAndVBaseOffsets - Add vcall offsets and vbase offsets for the
573  /// given base subobject.
574  void AddVCallAndVBaseOffsets(BaseSubobject Base, bool BaseIsVirtual,
575  CharUnits RealBaseOffset);
576 
577  /// AddVCallOffsets - Add vcall offsets for the given base subobject.
578  void AddVCallOffsets(BaseSubobject Base, CharUnits VBaseOffset);
579 
580  /// AddVBaseOffsets - Add vbase offsets for the given class.
581  void AddVBaseOffsets(const CXXRecordDecl *Base,
582  CharUnits OffsetInLayoutClass);
583 
584  /// getCurrentOffsetOffset - Get the current vcall or vbase offset offset in
585  /// chars, relative to the vtable address point.
586  CharUnits getCurrentOffsetOffset() const;
587 
588 public:
589  VCallAndVBaseOffsetBuilder(const ItaniumVTableContext &VTables,
590  const CXXRecordDecl *MostDerivedClass,
591  const CXXRecordDecl *LayoutClass,
592  const FinalOverriders *Overriders,
593  BaseSubobject Base, bool BaseIsVirtual,
594  CharUnits OffsetInLayoutClass)
595  : VTables(VTables), MostDerivedClass(MostDerivedClass),
596  LayoutClass(LayoutClass), Context(MostDerivedClass->getASTContext()),
597  Overriders(Overriders) {
598 
599  // Add vcall and vbase offsets.
600  AddVCallAndVBaseOffsets(Base, BaseIsVirtual, OffsetInLayoutClass);
601  }
602 
603  /// Methods for iterating over the components.
604  typedef VTableComponentVectorTy::const_reverse_iterator const_iterator;
605  const_iterator components_begin() const { return Components.rbegin(); }
606  const_iterator components_end() const { return Components.rend(); }
607 
608  const VCallOffsetMap &getVCallOffsets() const { return VCallOffsets; }
609  const VBaseOffsetOffsetsMapTy &getVBaseOffsetOffsets() const {
610  return VBaseOffsetOffsets;
611  }
612 };
613 
614 void
615 VCallAndVBaseOffsetBuilder::AddVCallAndVBaseOffsets(BaseSubobject Base,
616  bool BaseIsVirtual,
617  CharUnits RealBaseOffset) {
618  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base.getBase());
619 
620  // Itanium C++ ABI 2.5.2:
621  // ..in classes sharing a virtual table with a primary base class, the vcall
622  // and vbase offsets added by the derived class all come before the vcall
623  // and vbase offsets required by the base class, so that the latter may be
624  // laid out as required by the base class without regard to additions from
625  // the derived class(es).
626 
627  // (Since we're emitting the vcall and vbase offsets in reverse order, we'll
628  // emit them for the primary base first).
629  if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
630  bool PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual();
631 
632  CharUnits PrimaryBaseOffset;
633 
634  // Get the base offset of the primary base.
635  if (PrimaryBaseIsVirtual) {
636  assert(Layout.getVBaseClassOffset(PrimaryBase).isZero() &&
637  "Primary vbase should have a zero offset!");
638 
639  const ASTRecordLayout &MostDerivedClassLayout =
640  Context.getASTRecordLayout(MostDerivedClass);
641 
642  PrimaryBaseOffset =
643  MostDerivedClassLayout.getVBaseClassOffset(PrimaryBase);
644  } else {
645  assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
646  "Primary base should have a zero offset!");
647 
648  PrimaryBaseOffset = Base.getBaseOffset();
649  }
650 
651  AddVCallAndVBaseOffsets(
652  BaseSubobject(PrimaryBase,PrimaryBaseOffset),
653  PrimaryBaseIsVirtual, RealBaseOffset);
654  }
655 
656  AddVBaseOffsets(Base.getBase(), RealBaseOffset);
657 
658  // We only want to add vcall offsets for virtual bases.
659  if (BaseIsVirtual)
660  AddVCallOffsets(Base, RealBaseOffset);
661 }
662 
663 CharUnits VCallAndVBaseOffsetBuilder::getCurrentOffsetOffset() const {
664  // OffsetIndex is the index of this vcall or vbase offset, relative to the
665  // vtable address point. (We subtract 3 to account for the information just
666  // above the address point, the RTTI info, the offset to top, and the
667  // vcall offset itself).
668  int64_t OffsetIndex = -(int64_t)(3 + Components.size());
669 
670  // Under the relative ABI, the offset widths are 32-bit ints instead of
671  // pointer widths.
672  CharUnits OffsetWidth = Context.toCharUnitsFromBits(
673  VTables.isRelativeLayout() ? 32
674  : Context.getTargetInfo().getPointerWidth(0));
675  CharUnits OffsetOffset = OffsetWidth * OffsetIndex;
676 
677  return OffsetOffset;
678 }
679 
680 void VCallAndVBaseOffsetBuilder::AddVCallOffsets(BaseSubobject Base,
681  CharUnits VBaseOffset) {
682  const CXXRecordDecl *RD = Base.getBase();
683  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
684 
685  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
686 
687  // Handle the primary base first.
688  // We only want to add vcall offsets if the base is non-virtual; a virtual
689  // primary base will have its vcall and vbase offsets emitted already.
690  if (PrimaryBase && !Layout.isPrimaryBaseVirtual()) {
691  // Get the base offset of the primary base.
692  assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
693  "Primary base should have a zero offset!");
694 
695  AddVCallOffsets(BaseSubobject(PrimaryBase, Base.getBaseOffset()),
696  VBaseOffset);
697  }
698 
699  // Add the vcall offsets.
700  for (const auto *MD : RD->methods()) {
702  continue;
703  MD = MD->getCanonicalDecl();
704 
705  CharUnits OffsetOffset = getCurrentOffsetOffset();
706 
707  // Don't add a vcall offset if we already have one for this member function
708  // signature.
709  if (!VCallOffsets.AddVCallOffset(MD, OffsetOffset))
710  continue;
711 
713 
714  if (Overriders) {
715  // Get the final overrider.
716  FinalOverriders::OverriderInfo Overrider =
717  Overriders->getOverrider(MD, Base.getBaseOffset());
718 
719  /// The vcall offset is the offset from the virtual base to the object
720  /// where the function was overridden.
721  Offset = Overrider.Offset - VBaseOffset;
722  }
723 
724  Components.push_back(
726  }
727 
728  // And iterate over all non-virtual bases (ignoring the primary base).
729  for (const auto &B : RD->bases()) {
730  if (B.isVirtual())
731  continue;
732 
733  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
734  if (BaseDecl == PrimaryBase)
735  continue;
736 
737  // Get the base offset of this base.
738  CharUnits BaseOffset = Base.getBaseOffset() +
739  Layout.getBaseClassOffset(BaseDecl);
740 
741  AddVCallOffsets(BaseSubobject(BaseDecl, BaseOffset),
742  VBaseOffset);
743  }
744 }
745 
746 void
747 VCallAndVBaseOffsetBuilder::AddVBaseOffsets(const CXXRecordDecl *RD,
748  CharUnits OffsetInLayoutClass) {
749  const ASTRecordLayout &LayoutClassLayout =
750  Context.getASTRecordLayout(LayoutClass);
751 
752  // Add vbase offsets.
753  for (const auto &B : RD->bases()) {
754  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
755 
756  // Check if this is a virtual base that we haven't visited before.
757  if (B.isVirtual() && VisitedVirtualBases.insert(BaseDecl).second) {
758  CharUnits Offset =
759  LayoutClassLayout.getVBaseClassOffset(BaseDecl) - OffsetInLayoutClass;
760 
761  // Add the vbase offset offset.
762  assert(!VBaseOffsetOffsets.count(BaseDecl) &&
763  "vbase offset offset already exists!");
764 
765  CharUnits VBaseOffsetOffset = getCurrentOffsetOffset();
766  VBaseOffsetOffsets.insert(
767  std::make_pair(BaseDecl, VBaseOffsetOffset));
768 
769  Components.push_back(
771  }
772 
773  // Check the base class looking for more vbase offsets.
774  AddVBaseOffsets(BaseDecl, OffsetInLayoutClass);
775  }
776 }
777 
778 /// ItaniumVTableBuilder - Class for building vtable layout information.
779 class ItaniumVTableBuilder {
780 public:
781  /// PrimaryBasesSetVectorTy - A set vector of direct and indirect
782  /// primary bases.
784  PrimaryBasesSetVectorTy;
785 
786  typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits>
787  VBaseOffsetOffsetsMapTy;
788 
789  typedef VTableLayout::AddressPointsMapTy AddressPointsMapTy;
790 
791  typedef llvm::DenseMap<GlobalDecl, int64_t> MethodVTableIndicesTy;
792 
793 private:
794  /// VTables - Global vtable information.
795  ItaniumVTableContext &VTables;
796 
797  /// MostDerivedClass - The most derived class for which we're building this
798  /// vtable.
799  const CXXRecordDecl *MostDerivedClass;
800 
801  /// MostDerivedClassOffset - If we're building a construction vtable, this
802  /// holds the offset from the layout class to the most derived class.
803  const CharUnits MostDerivedClassOffset;
804 
805  /// MostDerivedClassIsVirtual - Whether the most derived class is a virtual
806  /// base. (This only makes sense when building a construction vtable).
807  bool MostDerivedClassIsVirtual;
808 
809  /// LayoutClass - The class we're using for layout information. Will be
810  /// different than the most derived class if we're building a construction
811  /// vtable.
812  const CXXRecordDecl *LayoutClass;
813 
814  /// Context - The ASTContext which we will use for layout information.
815  ASTContext &Context;
816 
817  /// FinalOverriders - The final overriders of the most derived class.
818  const FinalOverriders Overriders;
819 
820  /// VCallOffsetsForVBases - Keeps track of vcall offsets for the virtual
821  /// bases in this vtable.
822  llvm::DenseMap<const CXXRecordDecl *, VCallOffsetMap> VCallOffsetsForVBases;
823 
824  /// VBaseOffsetOffsets - Contains the offsets of the virtual base offsets for
825  /// the most derived class.
826  VBaseOffsetOffsetsMapTy VBaseOffsetOffsets;
827 
828  /// Components - The components of the vtable being built.
830 
831  /// AddressPoints - Address points for the vtable being built.
832  AddressPointsMapTy AddressPoints;
833 
834  /// MethodInfo - Contains information about a method in a vtable.
835  /// (Used for computing 'this' pointer adjustment thunks.
836  struct MethodInfo {
837  /// BaseOffset - The base offset of this method.
838  const CharUnits BaseOffset;
839 
840  /// BaseOffsetInLayoutClass - The base offset in the layout class of this
841  /// method.
842  const CharUnits BaseOffsetInLayoutClass;
843 
844  /// VTableIndex - The index in the vtable that this method has.
845  /// (For destructors, this is the index of the complete destructor).
846  const uint64_t VTableIndex;
847 
848  MethodInfo(CharUnits BaseOffset, CharUnits BaseOffsetInLayoutClass,
849  uint64_t VTableIndex)
850  : BaseOffset(BaseOffset),
851  BaseOffsetInLayoutClass(BaseOffsetInLayoutClass),
852  VTableIndex(VTableIndex) { }
853 
854  MethodInfo()
855  : BaseOffset(CharUnits::Zero()),
856  BaseOffsetInLayoutClass(CharUnits::Zero()),
857  VTableIndex(0) { }
858 
859  MethodInfo(MethodInfo const&) = default;
860  };
861 
862  typedef llvm::DenseMap<const CXXMethodDecl *, MethodInfo> MethodInfoMapTy;
863 
864  /// MethodInfoMap - The information for all methods in the vtable we're
865  /// currently building.
866  MethodInfoMapTy MethodInfoMap;
867 
868  /// MethodVTableIndices - Contains the index (relative to the vtable address
869  /// point) where the function pointer for a virtual function is stored.
870  MethodVTableIndicesTy MethodVTableIndices;
871 
872  typedef llvm::DenseMap<uint64_t, ThunkInfo> VTableThunksMapTy;
873 
874  /// VTableThunks - The thunks by vtable index in the vtable currently being
875  /// built.
876  VTableThunksMapTy VTableThunks;
877 
878  typedef SmallVector<ThunkInfo, 1> ThunkInfoVectorTy;
879  typedef llvm::DenseMap<const CXXMethodDecl *, ThunkInfoVectorTy> ThunksMapTy;
880 
881  /// Thunks - A map that contains all the thunks needed for all methods in the
882  /// most derived class for which the vtable is currently being built.
883  ThunksMapTy Thunks;
884 
885  /// AddThunk - Add a thunk for the given method.
886  void AddThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk);
887 
888  /// ComputeThisAdjustments - Compute the 'this' pointer adjustments for the
889  /// part of the vtable we're currently building.
890  void ComputeThisAdjustments();
891 
892  typedef llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBasesSetTy;
893 
894  /// PrimaryVirtualBases - All known virtual bases who are a primary base of
895  /// some other base.
896  VisitedVirtualBasesSetTy PrimaryVirtualBases;
897 
898  /// ComputeReturnAdjustment - Compute the return adjustment given a return
899  /// adjustment base offset.
900  ReturnAdjustment ComputeReturnAdjustment(BaseOffset Offset);
901 
902  /// ComputeThisAdjustmentBaseOffset - Compute the base offset for adjusting
903  /// the 'this' pointer from the base subobject to the derived subobject.
904  BaseOffset ComputeThisAdjustmentBaseOffset(BaseSubobject Base,
905  BaseSubobject Derived) const;
906 
907  /// ComputeThisAdjustment - Compute the 'this' pointer adjustment for the
908  /// given virtual member function, its offset in the layout class and its
909  /// final overrider.
911  ComputeThisAdjustment(const CXXMethodDecl *MD,
912  CharUnits BaseOffsetInLayoutClass,
913  FinalOverriders::OverriderInfo Overrider);
914 
915  /// AddMethod - Add a single virtual member function to the vtable
916  /// components vector.
917  void AddMethod(const CXXMethodDecl *MD, ReturnAdjustment ReturnAdjustment);
918 
919  /// IsOverriderUsed - Returns whether the overrider will ever be used in this
920  /// part of the vtable.
921  ///
922  /// Itanium C++ ABI 2.5.2:
923  ///
924  /// struct A { virtual void f(); };
925  /// struct B : virtual public A { int i; };
926  /// struct C : virtual public A { int j; };
927  /// struct D : public B, public C {};
928  ///
929  /// When B and C are declared, A is a primary base in each case, so although
930  /// vcall offsets are allocated in the A-in-B and A-in-C vtables, no this
931  /// adjustment is required and no thunk is generated. However, inside D
932  /// objects, A is no longer a primary base of C, so if we allowed calls to
933  /// C::f() to use the copy of A's vtable in the C subobject, we would need
934  /// to adjust this from C* to B::A*, which would require a third-party
935  /// thunk. Since we require that a call to C::f() first convert to A*,
936  /// C-in-D's copy of A's vtable is never referenced, so this is not
937  /// necessary.
938  bool IsOverriderUsed(const CXXMethodDecl *Overrider,
939  CharUnits BaseOffsetInLayoutClass,
940  const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
941  CharUnits FirstBaseOffsetInLayoutClass) const;
942 
943 
944  /// AddMethods - Add the methods of this base subobject and all its
945  /// primary bases to the vtable components vector.
946  void AddMethods(BaseSubobject Base, CharUnits BaseOffsetInLayoutClass,
947  const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
948  CharUnits FirstBaseOffsetInLayoutClass,
949  PrimaryBasesSetVectorTy &PrimaryBases);
950 
951  // LayoutVTable - Layout the vtable for the given base class, including its
952  // secondary vtables and any vtables for virtual bases.
953  void LayoutVTable();
954 
955  /// LayoutPrimaryAndSecondaryVTables - Layout the primary vtable for the
956  /// given base subobject, as well as all its secondary vtables.
957  ///
958  /// \param BaseIsMorallyVirtual whether the base subobject is a virtual base
959  /// or a direct or indirect base of a virtual base.
960  ///
961  /// \param BaseIsVirtualInLayoutClass - Whether the base subobject is virtual
962  /// in the layout class.
963  void LayoutPrimaryAndSecondaryVTables(BaseSubobject Base,
964  bool BaseIsMorallyVirtual,
965  bool BaseIsVirtualInLayoutClass,
966  CharUnits OffsetInLayoutClass);
967 
968  /// LayoutSecondaryVTables - Layout the secondary vtables for the given base
969  /// subobject.
970  ///
971  /// \param BaseIsMorallyVirtual whether the base subobject is a virtual base
972  /// or a direct or indirect base of a virtual base.
973  void LayoutSecondaryVTables(BaseSubobject Base, bool BaseIsMorallyVirtual,
974  CharUnits OffsetInLayoutClass);
975 
976  /// DeterminePrimaryVirtualBases - Determine the primary virtual bases in this
977  /// class hierarchy.
978  void DeterminePrimaryVirtualBases(const CXXRecordDecl *RD,
979  CharUnits OffsetInLayoutClass,
980  VisitedVirtualBasesSetTy &VBases);
981 
982  /// LayoutVTablesForVirtualBases - Layout vtables for all virtual bases of the
983  /// given base (excluding any primary bases).
984  void LayoutVTablesForVirtualBases(const CXXRecordDecl *RD,
985  VisitedVirtualBasesSetTy &VBases);
986 
987  /// isBuildingConstructionVTable - Return whether this vtable builder is
988  /// building a construction vtable.
989  bool isBuildingConstructorVTable() const {
990  return MostDerivedClass != LayoutClass;
991  }
992 
993 public:
994  /// Component indices of the first component of each of the vtables in the
995  /// vtable group.
996  SmallVector<size_t, 4> VTableIndices;
997 
998  ItaniumVTableBuilder(ItaniumVTableContext &VTables,
999  const CXXRecordDecl *MostDerivedClass,
1000  CharUnits MostDerivedClassOffset,
1001  bool MostDerivedClassIsVirtual,
1002  const CXXRecordDecl *LayoutClass)
1003  : VTables(VTables), MostDerivedClass(MostDerivedClass),
1004  MostDerivedClassOffset(MostDerivedClassOffset),
1005  MostDerivedClassIsVirtual(MostDerivedClassIsVirtual),
1006  LayoutClass(LayoutClass), Context(MostDerivedClass->getASTContext()),
1007  Overriders(MostDerivedClass, MostDerivedClassOffset, LayoutClass) {
1008  assert(!Context.getTargetInfo().getCXXABI().isMicrosoft());
1009 
1010  LayoutVTable();
1011 
1012  if (Context.getLangOpts().DumpVTableLayouts)
1013  dumpLayout(llvm::outs());
1014  }
1015 
1016  uint64_t getNumThunks() const {
1017  return Thunks.size();
1018  }
1019 
1020  ThunksMapTy::const_iterator thunks_begin() const {
1021  return Thunks.begin();
1022  }
1023 
1024  ThunksMapTy::const_iterator thunks_end() const {
1025  return Thunks.end();
1026  }
1027 
1028  const VBaseOffsetOffsetsMapTy &getVBaseOffsetOffsets() const {
1029  return VBaseOffsetOffsets;
1030  }
1031 
1032  const AddressPointsMapTy &getAddressPoints() const {
1033  return AddressPoints;
1034  }
1035 
1036  MethodVTableIndicesTy::const_iterator vtable_indices_begin() const {
1037  return MethodVTableIndices.begin();
1038  }
1039 
1040  MethodVTableIndicesTy::const_iterator vtable_indices_end() const {
1041  return MethodVTableIndices.end();
1042  }
1043 
1044  ArrayRef<VTableComponent> vtable_components() const { return Components; }
1045 
1046  AddressPointsMapTy::const_iterator address_points_begin() const {
1047  return AddressPoints.begin();
1048  }
1049 
1050  AddressPointsMapTy::const_iterator address_points_end() const {
1051  return AddressPoints.end();
1052  }
1053 
1054  VTableThunksMapTy::const_iterator vtable_thunks_begin() const {
1055  return VTableThunks.begin();
1056  }
1057 
1058  VTableThunksMapTy::const_iterator vtable_thunks_end() const {
1059  return VTableThunks.end();
1060  }
1061 
1062  /// dumpLayout - Dump the vtable layout.
1063  void dumpLayout(raw_ostream&);
1064 };
1065 
1066 void ItaniumVTableBuilder::AddThunk(const CXXMethodDecl *MD,
1067  const ThunkInfo &Thunk) {
1068  assert(!isBuildingConstructorVTable() &&
1069  "Can't add thunks for construction vtable");
1070 
1071  SmallVectorImpl<ThunkInfo> &ThunksVector = Thunks[MD];
1072 
1073  // Check if we have this thunk already.
1074  if (llvm::is_contained(ThunksVector, Thunk))
1075  return;
1076 
1077  ThunksVector.push_back(Thunk);
1078 }
1079 
1080 typedef llvm::SmallPtrSet<const CXXMethodDecl *, 8> OverriddenMethodsSetTy;
1081 
1082 /// Visit all the methods overridden by the given method recursively,
1083 /// in a depth-first pre-order. The Visitor's visitor method returns a bool
1084 /// indicating whether to continue the recursion for the given overridden
1085 /// method (i.e. returning false stops the iteration).
1086 template <class VisitorTy>
1087 static void
1088 visitAllOverriddenMethods(const CXXMethodDecl *MD, VisitorTy &Visitor) {
1089  assert(VTableContextBase::hasVtableSlot(MD) && "Method is not virtual!");
1090 
1091  for (const CXXMethodDecl *OverriddenMD : MD->overridden_methods()) {
1092  if (!Visitor(OverriddenMD))
1093  continue;
1094  visitAllOverriddenMethods(OverriddenMD, Visitor);
1095  }
1096 }
1097 
1098 /// ComputeAllOverriddenMethods - Given a method decl, will return a set of all
1099 /// the overridden methods that the function decl overrides.
1100 static void
1101 ComputeAllOverriddenMethods(const CXXMethodDecl *MD,
1102  OverriddenMethodsSetTy& OverriddenMethods) {
1103  auto OverriddenMethodsCollector = [&](const CXXMethodDecl *MD) {
1104  // Don't recurse on this method if we've already collected it.
1105  return OverriddenMethods.insert(MD).second;
1106  };
1107  visitAllOverriddenMethods(MD, OverriddenMethodsCollector);
1108 }
1109 
1110 void ItaniumVTableBuilder::ComputeThisAdjustments() {
1111  // Now go through the method info map and see if any of the methods need
1112  // 'this' pointer adjustments.
1113  for (const auto &MI : MethodInfoMap) {
1114  const CXXMethodDecl *MD = MI.first;
1115  const MethodInfo &MethodInfo = MI.second;
1116 
1117  // Ignore adjustments for unused function pointers.
1118  uint64_t VTableIndex = MethodInfo.VTableIndex;
1119  if (Components[VTableIndex].getKind() ==
1121  continue;
1122 
1123  // Get the final overrider for this method.
1124  FinalOverriders::OverriderInfo Overrider =
1125  Overriders.getOverrider(MD, MethodInfo.BaseOffset);
1126 
1127  // Check if we need an adjustment at all.
1128  if (MethodInfo.BaseOffsetInLayoutClass == Overrider.Offset) {
1129  // When a return thunk is needed by a derived class that overrides a
1130  // virtual base, gcc uses a virtual 'this' adjustment as well.
1131  // While the thunk itself might be needed by vtables in subclasses or
1132  // in construction vtables, there doesn't seem to be a reason for using
1133  // the thunk in this vtable. Still, we do so to match gcc.
1134  if (VTableThunks.lookup(VTableIndex).Return.isEmpty())
1135  continue;
1136  }
1137 
1139  ComputeThisAdjustment(MD, MethodInfo.BaseOffsetInLayoutClass, Overrider);
1140 
1141  if (ThisAdjustment.isEmpty())
1142  continue;
1143 
1144  // Add it.
1145  VTableThunks[VTableIndex].This = ThisAdjustment;
1146 
1147  if (isa<CXXDestructorDecl>(MD)) {
1148  // Add an adjustment for the deleting destructor as well.
1149  VTableThunks[VTableIndex + 1].This = ThisAdjustment;
1150  }
1151  }
1152 
1153  /// Clear the method info map.
1154  MethodInfoMap.clear();
1155 
1156  if (isBuildingConstructorVTable()) {
1157  // We don't need to store thunk information for construction vtables.
1158  return;
1159  }
1160 
1161  for (const auto &TI : VTableThunks) {
1162  const VTableComponent &Component = Components[TI.first];
1163  const ThunkInfo &Thunk = TI.second;
1164  const CXXMethodDecl *MD;
1165 
1166  switch (Component.getKind()) {
1167  default:
1168  llvm_unreachable("Unexpected vtable component kind!");
1170  MD = Component.getFunctionDecl();
1171  break;
1173  MD = Component.getDestructorDecl();
1174  break;
1176  // We've already added the thunk when we saw the complete dtor pointer.
1177  continue;
1178  }
1179 
1180  if (MD->getParent() == MostDerivedClass)
1181  AddThunk(MD, Thunk);
1182  }
1183 }
1184 
1186 ItaniumVTableBuilder::ComputeReturnAdjustment(BaseOffset Offset) {
1187  ReturnAdjustment Adjustment;
1188 
1189  if (!Offset.isEmpty()) {
1190  if (Offset.VirtualBase) {
1191  // Get the virtual base offset offset.
1192  if (Offset.DerivedClass == MostDerivedClass) {
1193  // We can get the offset offset directly from our map.
1194  Adjustment.Virtual.Itanium.VBaseOffsetOffset =
1195  VBaseOffsetOffsets.lookup(Offset.VirtualBase).getQuantity();
1196  } else {
1197  Adjustment.Virtual.Itanium.VBaseOffsetOffset =
1198  VTables.getVirtualBaseOffsetOffset(Offset.DerivedClass,
1199  Offset.VirtualBase).getQuantity();
1200  }
1201  }
1202 
1203  Adjustment.NonVirtual = Offset.NonVirtualOffset.getQuantity();
1204  }
1205 
1206  return Adjustment;
1207 }
1208 
1209 BaseOffset ItaniumVTableBuilder::ComputeThisAdjustmentBaseOffset(
1210  BaseSubobject Base, BaseSubobject Derived) const {
1211  const CXXRecordDecl *BaseRD = Base.getBase();
1212  const CXXRecordDecl *DerivedRD = Derived.getBase();
1213 
1214  CXXBasePaths Paths(/*FindAmbiguities=*/true,
1215  /*RecordPaths=*/true, /*DetectVirtual=*/true);
1216 
1217  if (!DerivedRD->isDerivedFrom(BaseRD, Paths))
1218  llvm_unreachable("Class must be derived from the passed in base class!");
1219 
1220  // We have to go through all the paths, and see which one leads us to the
1221  // right base subobject.
1222  for (const CXXBasePath &Path : Paths) {
1223  BaseOffset Offset = ComputeBaseOffset(Context, DerivedRD, Path);
1224 
1225  CharUnits OffsetToBaseSubobject = Offset.NonVirtualOffset;
1226 
1227  if (Offset.VirtualBase) {
1228  // If we have a virtual base class, the non-virtual offset is relative
1229  // to the virtual base class offset.
1230  const ASTRecordLayout &LayoutClassLayout =
1231  Context.getASTRecordLayout(LayoutClass);
1232 
1233  /// Get the virtual base offset, relative to the most derived class
1234  /// layout.
1235  OffsetToBaseSubobject +=
1236  LayoutClassLayout.getVBaseClassOffset(Offset.VirtualBase);
1237  } else {
1238  // Otherwise, the non-virtual offset is relative to the derived class
1239  // offset.
1240  OffsetToBaseSubobject += Derived.getBaseOffset();
1241  }
1242 
1243  // Check if this path gives us the right base subobject.
1244  if (OffsetToBaseSubobject == Base.getBaseOffset()) {
1245  // Since we're going from the base class _to_ the derived class, we'll
1246  // invert the non-virtual offset here.
1247  Offset.NonVirtualOffset = -Offset.NonVirtualOffset;
1248  return Offset;
1249  }
1250  }
1251 
1252  return BaseOffset();
1253 }
1254 
1255 ThisAdjustment ItaniumVTableBuilder::ComputeThisAdjustment(
1256  const CXXMethodDecl *MD, CharUnits BaseOffsetInLayoutClass,
1257  FinalOverriders::OverriderInfo Overrider) {
1258  // Ignore adjustments for pure virtual member functions.
1259  if (Overrider.Method->isPure())
1260  return ThisAdjustment();
1261 
1262  BaseSubobject OverriddenBaseSubobject(MD->getParent(),
1263  BaseOffsetInLayoutClass);
1264 
1265  BaseSubobject OverriderBaseSubobject(Overrider.Method->getParent(),
1266  Overrider.Offset);
1267 
1268  // Compute the adjustment offset.
1269  BaseOffset Offset = ComputeThisAdjustmentBaseOffset(OverriddenBaseSubobject,
1270  OverriderBaseSubobject);
1271  if (Offset.isEmpty())
1272  return ThisAdjustment();
1273 
1274  ThisAdjustment Adjustment;
1275 
1276  if (Offset.VirtualBase) {
1277  // Get the vcall offset map for this virtual base.
1278  VCallOffsetMap &VCallOffsets = VCallOffsetsForVBases[Offset.VirtualBase];
1279 
1280  if (VCallOffsets.empty()) {
1281  // We don't have vcall offsets for this virtual base, go ahead and
1282  // build them.
1283  VCallAndVBaseOffsetBuilder Builder(
1284  VTables, MostDerivedClass, MostDerivedClass,
1285  /*Overriders=*/nullptr,
1286  BaseSubobject(Offset.VirtualBase, CharUnits::Zero()),
1287  /*BaseIsVirtual=*/true,
1288  /*OffsetInLayoutClass=*/
1289  CharUnits::Zero());
1290 
1291  VCallOffsets = Builder.getVCallOffsets();
1292  }
1293 
1294  Adjustment.Virtual.Itanium.VCallOffsetOffset =
1295  VCallOffsets.getVCallOffsetOffset(MD).getQuantity();
1296  }
1297 
1298  // Set the non-virtual part of the adjustment.
1299  Adjustment.NonVirtual = Offset.NonVirtualOffset.getQuantity();
1300 
1301  return Adjustment;
1302 }
1303 
1304 void ItaniumVTableBuilder::AddMethod(const CXXMethodDecl *MD,
1306  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1307  assert(ReturnAdjustment.isEmpty() &&
1308  "Destructor can't have return adjustment!");
1309 
1310  // Add both the complete destructor and the deleting destructor.
1311  Components.push_back(VTableComponent::MakeCompleteDtor(DD));
1312  Components.push_back(VTableComponent::MakeDeletingDtor(DD));
1313  } else {
1314  // Add the return adjustment if necessary.
1315  if (!ReturnAdjustment.isEmpty())
1316  VTableThunks[Components.size()].Return = ReturnAdjustment;
1317 
1318  // Add the function.
1319  Components.push_back(VTableComponent::MakeFunction(MD));
1320  }
1321 }
1322 
1323 /// OverridesIndirectMethodInBase - Return whether the given member function
1324 /// overrides any methods in the set of given bases.
1325 /// Unlike OverridesMethodInBase, this checks "overriders of overriders".
1326 /// For example, if we have:
1327 ///
1328 /// struct A { virtual void f(); }
1329 /// struct B : A { virtual void f(); }
1330 /// struct C : B { virtual void f(); }
1331 ///
1332 /// OverridesIndirectMethodInBase will return true if given C::f as the method
1333 /// and { A } as the set of bases.
1334 static bool OverridesIndirectMethodInBases(
1335  const CXXMethodDecl *MD,
1337  if (Bases.count(MD->getParent()))
1338  return true;
1339 
1340  for (const CXXMethodDecl *OverriddenMD : MD->overridden_methods()) {
1341  // Check "indirect overriders".
1342  if (OverridesIndirectMethodInBases(OverriddenMD, Bases))
1343  return true;
1344  }
1345 
1346  return false;
1347 }
1348 
1349 bool ItaniumVTableBuilder::IsOverriderUsed(
1350  const CXXMethodDecl *Overrider, CharUnits BaseOffsetInLayoutClass,
1351  const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
1352  CharUnits FirstBaseOffsetInLayoutClass) const {
1353  // If the base and the first base in the primary base chain have the same
1354  // offsets, then this overrider will be used.
1355  if (BaseOffsetInLayoutClass == FirstBaseOffsetInLayoutClass)
1356  return true;
1357 
1358  // We know now that Base (or a direct or indirect base of it) is a primary
1359  // base in part of the class hierarchy, but not a primary base in the most
1360  // derived class.
1361 
1362  // If the overrider is the first base in the primary base chain, we know
1363  // that the overrider will be used.
1364  if (Overrider->getParent() == FirstBaseInPrimaryBaseChain)
1365  return true;
1366 
1368 
1369  const CXXRecordDecl *RD = FirstBaseInPrimaryBaseChain;
1370  PrimaryBases.insert(RD);
1371 
1372  // Now traverse the base chain, starting with the first base, until we find
1373  // the base that is no longer a primary base.
1374  while (true) {
1375  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1376  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
1377 
1378  if (!PrimaryBase)
1379  break;
1380 
1381  if (Layout.isPrimaryBaseVirtual()) {
1382  assert(Layout.getVBaseClassOffset(PrimaryBase).isZero() &&
1383  "Primary base should always be at offset 0!");
1384 
1385  const ASTRecordLayout &LayoutClassLayout =
1386  Context.getASTRecordLayout(LayoutClass);
1387 
1388  // Now check if this is the primary base that is not a primary base in the
1389  // most derived class.
1390  if (LayoutClassLayout.getVBaseClassOffset(PrimaryBase) !=
1391  FirstBaseOffsetInLayoutClass) {
1392  // We found it, stop walking the chain.
1393  break;
1394  }
1395  } else {
1396  assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
1397  "Primary base should always be at offset 0!");
1398  }
1399 
1400  if (!PrimaryBases.insert(PrimaryBase))
1401  llvm_unreachable("Found a duplicate primary base!");
1402 
1403  RD = PrimaryBase;
1404  }
1405 
1406  // If the final overrider is an override of one of the primary bases,
1407  // then we know that it will be used.
1408  return OverridesIndirectMethodInBases(Overrider, PrimaryBases);
1409 }
1410 
1411 typedef llvm::SmallSetVector<const CXXRecordDecl *, 8> BasesSetVectorTy;
1412 
1413 /// FindNearestOverriddenMethod - Given a method, returns the overridden method
1414 /// from the nearest base. Returns null if no method was found.
1415 /// The Bases are expected to be sorted in a base-to-derived order.
1416 static const CXXMethodDecl *
1417 FindNearestOverriddenMethod(const CXXMethodDecl *MD,
1418  BasesSetVectorTy &Bases) {
1419  OverriddenMethodsSetTy OverriddenMethods;
1420  ComputeAllOverriddenMethods(MD, OverriddenMethods);
1421 
1422  for (const CXXRecordDecl *PrimaryBase : llvm::reverse(Bases)) {
1423  // Now check the overridden methods.
1424  for (const CXXMethodDecl *OverriddenMD : OverriddenMethods) {
1425  // We found our overridden method.
1426  if (OverriddenMD->getParent() == PrimaryBase)
1427  return OverriddenMD;
1428  }
1429  }
1430 
1431  return nullptr;
1432 }
1433 
1434 void ItaniumVTableBuilder::AddMethods(
1435  BaseSubobject Base, CharUnits BaseOffsetInLayoutClass,
1436  const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
1437  CharUnits FirstBaseOffsetInLayoutClass,
1438  PrimaryBasesSetVectorTy &PrimaryBases) {
1439  // Itanium C++ ABI 2.5.2:
1440  // The order of the virtual function pointers in a virtual table is the
1441  // order of declaration of the corresponding member functions in the class.
1442  //
1443  // There is an entry for any virtual function declared in a class,
1444  // whether it is a new function or overrides a base class function,
1445  // unless it overrides a function from the primary base, and conversion
1446  // between their return types does not require an adjustment.
1447 
1448  const CXXRecordDecl *RD = Base.getBase();
1449  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1450 
1451  if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
1452  CharUnits PrimaryBaseOffset;
1453  CharUnits PrimaryBaseOffsetInLayoutClass;
1454  if (Layout.isPrimaryBaseVirtual()) {
1455  assert(Layout.getVBaseClassOffset(PrimaryBase).isZero() &&
1456  "Primary vbase should have a zero offset!");
1457 
1458  const ASTRecordLayout &MostDerivedClassLayout =
1459  Context.getASTRecordLayout(MostDerivedClass);
1460 
1461  PrimaryBaseOffset =
1462  MostDerivedClassLayout.getVBaseClassOffset(PrimaryBase);
1463 
1464  const ASTRecordLayout &LayoutClassLayout =
1465  Context.getASTRecordLayout(LayoutClass);
1466 
1467  PrimaryBaseOffsetInLayoutClass =
1468  LayoutClassLayout.getVBaseClassOffset(PrimaryBase);
1469  } else {
1470  assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
1471  "Primary base should have a zero offset!");
1472 
1473  PrimaryBaseOffset = Base.getBaseOffset();
1474  PrimaryBaseOffsetInLayoutClass = BaseOffsetInLayoutClass;
1475  }
1476 
1477  AddMethods(BaseSubobject(PrimaryBase, PrimaryBaseOffset),
1478  PrimaryBaseOffsetInLayoutClass, FirstBaseInPrimaryBaseChain,
1479  FirstBaseOffsetInLayoutClass, PrimaryBases);
1480 
1481  if (!PrimaryBases.insert(PrimaryBase))
1482  llvm_unreachable("Found a duplicate primary base!");
1483  }
1484 
1485  typedef llvm::SmallVector<const CXXMethodDecl *, 8> NewVirtualFunctionsTy;
1486  NewVirtualFunctionsTy NewVirtualFunctions;
1487 
1488  llvm::SmallVector<const CXXMethodDecl*, 4> NewImplicitVirtualFunctions;
1489 
1490  // Now go through all virtual member functions and add them.
1491  for (const auto *MD : RD->methods()) {
1493  continue;
1494  MD = MD->getCanonicalDecl();
1495 
1496  // Get the final overrider.
1497  FinalOverriders::OverriderInfo Overrider =
1498  Overriders.getOverrider(MD, Base.getBaseOffset());
1499 
1500  // Check if this virtual member function overrides a method in a primary
1501  // base. If this is the case, and the return type doesn't require adjustment
1502  // then we can just use the member function from the primary base.
1503  if (const CXXMethodDecl *OverriddenMD =
1504  FindNearestOverriddenMethod(MD, PrimaryBases)) {
1505  if (ComputeReturnAdjustmentBaseOffset(Context, MD,
1506  OverriddenMD).isEmpty()) {
1507  // Replace the method info of the overridden method with our own
1508  // method.
1509  assert(MethodInfoMap.count(OverriddenMD) &&
1510  "Did not find the overridden method!");
1511  MethodInfo &OverriddenMethodInfo = MethodInfoMap[OverriddenMD];
1512 
1513  MethodInfo MethodInfo(Base.getBaseOffset(), BaseOffsetInLayoutClass,
1514  OverriddenMethodInfo.VTableIndex);
1515 
1516  assert(!MethodInfoMap.count(MD) &&
1517  "Should not have method info for this method yet!");
1518 
1519  MethodInfoMap.insert(std::make_pair(MD, MethodInfo));
1520  MethodInfoMap.erase(OverriddenMD);
1521 
1522  // If the overridden method exists in a virtual base class or a direct
1523  // or indirect base class of a virtual base class, we need to emit a
1524  // thunk if we ever have a class hierarchy where the base class is not
1525  // a primary base in the complete object.
1526  if (!isBuildingConstructorVTable() && OverriddenMD != MD) {
1527  // Compute the this adjustment.
1529  ComputeThisAdjustment(OverriddenMD, BaseOffsetInLayoutClass,
1530  Overrider);
1531 
1533  Overrider.Method->getParent() == MostDerivedClass) {
1534 
1535  // There's no return adjustment from OverriddenMD and MD,
1536  // but that doesn't mean there isn't one between MD and
1537  // the final overrider.
1538  BaseOffset ReturnAdjustmentOffset =
1539  ComputeReturnAdjustmentBaseOffset(Context, Overrider.Method, MD);
1541  ComputeReturnAdjustment(ReturnAdjustmentOffset);
1542 
1543  // This is a virtual thunk for the most derived class, add it.
1544  AddThunk(Overrider.Method,
1546  }
1547  }
1548 
1549  continue;
1550  }
1551  }
1552 
1553  if (MD->isImplicit())
1554  NewImplicitVirtualFunctions.push_back(MD);
1555  else
1556  NewVirtualFunctions.push_back(MD);
1557  }
1558 
1559  std::stable_sort(
1560  NewImplicitVirtualFunctions.begin(), NewImplicitVirtualFunctions.end(),
1561  [](const CXXMethodDecl *A, const CXXMethodDecl *B) {
1562  if (A->isCopyAssignmentOperator() != B->isCopyAssignmentOperator())
1563  return A->isCopyAssignmentOperator();
1564  if (A->isMoveAssignmentOperator() != B->isMoveAssignmentOperator())
1565  return A->isMoveAssignmentOperator();
1566  if (isa<CXXDestructorDecl>(A) != isa<CXXDestructorDecl>(B))
1567  return isa<CXXDestructorDecl>(A);
1568  assert(A->getOverloadedOperator() == OO_EqualEqual &&
1569  B->getOverloadedOperator() == OO_EqualEqual &&
1570  "unexpected or duplicate implicit virtual function");
1571  // We rely on Sema to have declared the operator== members in the
1572  // same order as the corresponding operator<=> members.
1573  return false;
1574  });
1575  NewVirtualFunctions.append(NewImplicitVirtualFunctions.begin(),
1576  NewImplicitVirtualFunctions.end());
1577 
1578  for (const CXXMethodDecl *MD : NewVirtualFunctions) {
1579  // Get the final overrider.
1580  FinalOverriders::OverriderInfo Overrider =
1581  Overriders.getOverrider(MD, Base.getBaseOffset());
1582 
1583  // Insert the method info for this method.
1584  MethodInfo MethodInfo(Base.getBaseOffset(), BaseOffsetInLayoutClass,
1585  Components.size());
1586 
1587  assert(!MethodInfoMap.count(MD) &&
1588  "Should not have method info for this method yet!");
1589  MethodInfoMap.insert(std::make_pair(MD, MethodInfo));
1590 
1591  // Check if this overrider is going to be used.
1592  const CXXMethodDecl *OverriderMD = Overrider.Method;
1593  if (!IsOverriderUsed(OverriderMD, BaseOffsetInLayoutClass,
1594  FirstBaseInPrimaryBaseChain,
1595  FirstBaseOffsetInLayoutClass)) {
1596  Components.push_back(VTableComponent::MakeUnusedFunction(OverriderMD));
1597  continue;
1598  }
1599 
1600  // Check if this overrider needs a return adjustment.
1601  // We don't want to do this for pure virtual member functions.
1602  BaseOffset ReturnAdjustmentOffset;
1603  if (!OverriderMD->isPure()) {
1604  ReturnAdjustmentOffset =
1605  ComputeReturnAdjustmentBaseOffset(Context, OverriderMD, MD);
1606  }
1607 
1609  ComputeReturnAdjustment(ReturnAdjustmentOffset);
1610 
1611  AddMethod(Overrider.Method, ReturnAdjustment);
1612  }
1613 }
1614 
1615 void ItaniumVTableBuilder::LayoutVTable() {
1616  LayoutPrimaryAndSecondaryVTables(BaseSubobject(MostDerivedClass,
1617  CharUnits::Zero()),
1618  /*BaseIsMorallyVirtual=*/false,
1619  MostDerivedClassIsVirtual,
1620  MostDerivedClassOffset);
1621 
1622  VisitedVirtualBasesSetTy VBases;
1623 
1624  // Determine the primary virtual bases.
1625  DeterminePrimaryVirtualBases(MostDerivedClass, MostDerivedClassOffset,
1626  VBases);
1627  VBases.clear();
1628 
1629  LayoutVTablesForVirtualBases(MostDerivedClass, VBases);
1630 
1631  // -fapple-kext adds an extra entry at end of vtbl.
1632  bool IsAppleKext = Context.getLangOpts().AppleKext;
1633  if (IsAppleKext)
1634  Components.push_back(VTableComponent::MakeVCallOffset(CharUnits::Zero()));
1635 }
1636 
1637 void ItaniumVTableBuilder::LayoutPrimaryAndSecondaryVTables(
1638  BaseSubobject Base, bool BaseIsMorallyVirtual,
1639  bool BaseIsVirtualInLayoutClass, CharUnits OffsetInLayoutClass) {
1640  assert(Base.getBase()->isDynamicClass() && "class does not have a vtable!");
1641 
1642  unsigned VTableIndex = Components.size();
1643  VTableIndices.push_back(VTableIndex);
1644 
1645  // Add vcall and vbase offsets for this vtable.
1646  VCallAndVBaseOffsetBuilder Builder(
1647  VTables, MostDerivedClass, LayoutClass, &Overriders, Base,
1648  BaseIsVirtualInLayoutClass, OffsetInLayoutClass);
1649  Components.append(Builder.components_begin(), Builder.components_end());
1650 
1651  // Check if we need to add these vcall offsets.
1652  if (BaseIsVirtualInLayoutClass && !Builder.getVCallOffsets().empty()) {
1653  VCallOffsetMap &VCallOffsets = VCallOffsetsForVBases[Base.getBase()];
1654 
1655  if (VCallOffsets.empty())
1656  VCallOffsets = Builder.getVCallOffsets();
1657  }
1658 
1659  // If we're laying out the most derived class we want to keep track of the
1660  // virtual base class offset offsets.
1661  if (Base.getBase() == MostDerivedClass)
1662  VBaseOffsetOffsets = Builder.getVBaseOffsetOffsets();
1663 
1664  // Add the offset to top.
1665  CharUnits OffsetToTop = MostDerivedClassOffset - OffsetInLayoutClass;
1666  Components.push_back(VTableComponent::MakeOffsetToTop(OffsetToTop));
1667 
1668  // Next, add the RTTI.
1669  Components.push_back(VTableComponent::MakeRTTI(MostDerivedClass));
1670 
1671  uint64_t AddressPoint = Components.size();
1672 
1673  // Now go through all virtual member functions and add them.
1674  PrimaryBasesSetVectorTy PrimaryBases;
1675  AddMethods(Base, OffsetInLayoutClass,
1676  Base.getBase(), OffsetInLayoutClass,
1677  PrimaryBases);
1678 
1679  const CXXRecordDecl *RD = Base.getBase();
1680  if (RD == MostDerivedClass) {
1681  assert(MethodVTableIndices.empty());
1682  for (const auto &I : MethodInfoMap) {
1683  const CXXMethodDecl *MD = I.first;
1684  const MethodInfo &MI = I.second;
1685  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1686  MethodVTableIndices[GlobalDecl(DD, Dtor_Complete)]
1687  = MI.VTableIndex - AddressPoint;
1688  MethodVTableIndices[GlobalDecl(DD, Dtor_Deleting)]
1689  = MI.VTableIndex + 1 - AddressPoint;
1690  } else {
1691  MethodVTableIndices[MD] = MI.VTableIndex - AddressPoint;
1692  }
1693  }
1694  }
1695 
1696  // Compute 'this' pointer adjustments.
1697  ComputeThisAdjustments();
1698 
1699  // Add all address points.
1700  while (true) {
1701  AddressPoints.insert(
1702  std::make_pair(BaseSubobject(RD, OffsetInLayoutClass),
1704  unsigned(VTableIndices.size() - 1),
1705  unsigned(AddressPoint - VTableIndex)}));
1706 
1707  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1708  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
1709 
1710  if (!PrimaryBase)
1711  break;
1712 
1713  if (Layout.isPrimaryBaseVirtual()) {
1714  // Check if this virtual primary base is a primary base in the layout
1715  // class. If it's not, we don't want to add it.
1716  const ASTRecordLayout &LayoutClassLayout =
1717  Context.getASTRecordLayout(LayoutClass);
1718 
1719  if (LayoutClassLayout.getVBaseClassOffset(PrimaryBase) !=
1720  OffsetInLayoutClass) {
1721  // We don't want to add this class (or any of its primary bases).
1722  break;
1723  }
1724  }
1725 
1726  RD = PrimaryBase;
1727  }
1728 
1729  // Layout secondary vtables.
1730  LayoutSecondaryVTables(Base, BaseIsMorallyVirtual, OffsetInLayoutClass);
1731 }
1732 
1733 void
1734 ItaniumVTableBuilder::LayoutSecondaryVTables(BaseSubobject Base,
1735  bool BaseIsMorallyVirtual,
1736  CharUnits OffsetInLayoutClass) {
1737  // Itanium C++ ABI 2.5.2:
1738  // Following the primary virtual table of a derived class are secondary
1739  // virtual tables for each of its proper base classes, except any primary
1740  // base(s) with which it shares its primary virtual table.
1741 
1742  const CXXRecordDecl *RD = Base.getBase();
1743  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1744  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
1745 
1746  for (const auto &B : RD->bases()) {
1747  // Ignore virtual bases, we'll emit them later.
1748  if (B.isVirtual())
1749  continue;
1750 
1751  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
1752 
1753  // Ignore bases that don't have a vtable.
1754  if (!BaseDecl->isDynamicClass())
1755  continue;
1756 
1757  if (isBuildingConstructorVTable()) {
1758  // Itanium C++ ABI 2.6.4:
1759  // Some of the base class subobjects may not need construction virtual
1760  // tables, which will therefore not be present in the construction
1761  // virtual table group, even though the subobject virtual tables are
1762  // present in the main virtual table group for the complete object.
1763  if (!BaseIsMorallyVirtual && !BaseDecl->getNumVBases())
1764  continue;
1765  }
1766 
1767  // Get the base offset of this base.
1768  CharUnits RelativeBaseOffset = Layout.getBaseClassOffset(BaseDecl);
1769  CharUnits BaseOffset = Base.getBaseOffset() + RelativeBaseOffset;
1770 
1771  CharUnits BaseOffsetInLayoutClass =
1772  OffsetInLayoutClass + RelativeBaseOffset;
1773 
1774  // Don't emit a secondary vtable for a primary base. We might however want
1775  // to emit secondary vtables for other bases of this base.
1776  if (BaseDecl == PrimaryBase) {
1777  LayoutSecondaryVTables(BaseSubobject(BaseDecl, BaseOffset),
1778  BaseIsMorallyVirtual, BaseOffsetInLayoutClass);
1779  continue;
1780  }
1781 
1782  // Layout the primary vtable (and any secondary vtables) for this base.
1783  LayoutPrimaryAndSecondaryVTables(
1784  BaseSubobject(BaseDecl, BaseOffset),
1785  BaseIsMorallyVirtual,
1786  /*BaseIsVirtualInLayoutClass=*/false,
1787  BaseOffsetInLayoutClass);
1788  }
1789 }
1790 
1791 void ItaniumVTableBuilder::DeterminePrimaryVirtualBases(
1792  const CXXRecordDecl *RD, CharUnits OffsetInLayoutClass,
1793  VisitedVirtualBasesSetTy &VBases) {
1794  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1795 
1796  // Check if this base has a primary base.
1797  if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
1798 
1799  // Check if it's virtual.
1800  if (Layout.isPrimaryBaseVirtual()) {
1801  bool IsPrimaryVirtualBase = true;
1802 
1803  if (isBuildingConstructorVTable()) {
1804  // Check if the base is actually a primary base in the class we use for
1805  // layout.
1806  const ASTRecordLayout &LayoutClassLayout =
1807  Context.getASTRecordLayout(LayoutClass);
1808 
1809  CharUnits PrimaryBaseOffsetInLayoutClass =
1810  LayoutClassLayout.getVBaseClassOffset(PrimaryBase);
1811 
1812  // We know that the base is not a primary base in the layout class if
1813  // the base offsets are different.
1814  if (PrimaryBaseOffsetInLayoutClass != OffsetInLayoutClass)
1815  IsPrimaryVirtualBase = false;
1816  }
1817 
1818  if (IsPrimaryVirtualBase)
1819  PrimaryVirtualBases.insert(PrimaryBase);
1820  }
1821  }
1822 
1823  // Traverse bases, looking for more primary virtual bases.
1824  for (const auto &B : RD->bases()) {
1825  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
1826 
1827  CharUnits BaseOffsetInLayoutClass;
1828 
1829  if (B.isVirtual()) {
1830  if (!VBases.insert(BaseDecl).second)
1831  continue;
1832 
1833  const ASTRecordLayout &LayoutClassLayout =
1834  Context.getASTRecordLayout(LayoutClass);
1835 
1836  BaseOffsetInLayoutClass =
1837  LayoutClassLayout.getVBaseClassOffset(BaseDecl);
1838  } else {
1839  BaseOffsetInLayoutClass =
1840  OffsetInLayoutClass + Layout.getBaseClassOffset(BaseDecl);
1841  }
1842 
1843  DeterminePrimaryVirtualBases(BaseDecl, BaseOffsetInLayoutClass, VBases);
1844  }
1845 }
1846 
1847 void ItaniumVTableBuilder::LayoutVTablesForVirtualBases(
1848  const CXXRecordDecl *RD, VisitedVirtualBasesSetTy &VBases) {
1849  // Itanium C++ ABI 2.5.2:
1850  // Then come the virtual base virtual tables, also in inheritance graph
1851  // order, and again excluding primary bases (which share virtual tables with
1852  // the classes for which they are primary).
1853  for (const auto &B : RD->bases()) {
1854  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
1855 
1856  // Check if this base needs a vtable. (If it's virtual, not a primary base
1857  // of some other class, and we haven't visited it before).
1858  if (B.isVirtual() && BaseDecl->isDynamicClass() &&
1859  !PrimaryVirtualBases.count(BaseDecl) &&
1860  VBases.insert(BaseDecl).second) {
1861  const ASTRecordLayout &MostDerivedClassLayout =
1862  Context.getASTRecordLayout(MostDerivedClass);
1863  CharUnits BaseOffset =
1864  MostDerivedClassLayout.getVBaseClassOffset(BaseDecl);
1865 
1866  const ASTRecordLayout &LayoutClassLayout =
1867  Context.getASTRecordLayout(LayoutClass);
1868  CharUnits BaseOffsetInLayoutClass =
1869  LayoutClassLayout.getVBaseClassOffset(BaseDecl);
1870 
1871  LayoutPrimaryAndSecondaryVTables(
1872  BaseSubobject(BaseDecl, BaseOffset),
1873  /*BaseIsMorallyVirtual=*/true,
1874  /*BaseIsVirtualInLayoutClass=*/true,
1875  BaseOffsetInLayoutClass);
1876  }
1877 
1878  // We only need to check the base for virtual base vtables if it actually
1879  // has virtual bases.
1880  if (BaseDecl->getNumVBases())
1881  LayoutVTablesForVirtualBases(BaseDecl, VBases);
1882  }
1883 }
1884 
1885 /// dumpLayout - Dump the vtable layout.
1886 void ItaniumVTableBuilder::dumpLayout(raw_ostream &Out) {
1887  // FIXME: write more tests that actually use the dumpLayout output to prevent
1888  // ItaniumVTableBuilder regressions.
1889 
1890  if (isBuildingConstructorVTable()) {
1891  Out << "Construction vtable for ('";
1892  MostDerivedClass->printQualifiedName(Out);
1893  Out << "', ";
1894  Out << MostDerivedClassOffset.getQuantity() << ") in '";
1895  LayoutClass->printQualifiedName(Out);
1896  } else {
1897  Out << "Vtable for '";
1898  MostDerivedClass->printQualifiedName(Out);
1899  }
1900  Out << "' (" << Components.size() << " entries).\n";
1901 
1902  // Iterate through the address points and insert them into a new map where
1903  // they are keyed by the index and not the base object.
1904  // Since an address point can be shared by multiple subobjects, we use an
1905  // STL multimap.
1906  std::multimap<uint64_t, BaseSubobject> AddressPointsByIndex;
1907  for (const auto &AP : AddressPoints) {
1908  const BaseSubobject &Base = AP.first;
1909  uint64_t Index =
1910  VTableIndices[AP.second.VTableIndex] + AP.second.AddressPointIndex;
1911 
1912  AddressPointsByIndex.insert(std::make_pair(Index, Base));
1913  }
1914 
1915  for (unsigned I = 0, E = Components.size(); I != E; ++I) {
1916  uint64_t Index = I;
1917 
1918  Out << llvm::format("%4d | ", I);
1919 
1920  const VTableComponent &Component = Components[I];
1921 
1922  // Dump the component.
1923  switch (Component.getKind()) {
1924 
1926  Out << "vcall_offset ("
1927  << Component.getVCallOffset().getQuantity()
1928  << ")";
1929  break;
1930 
1932  Out << "vbase_offset ("
1933  << Component.getVBaseOffset().getQuantity()
1934  << ")";
1935  break;
1936 
1938  Out << "offset_to_top ("
1939  << Component.getOffsetToTop().getQuantity()
1940  << ")";
1941  break;
1942 
1944  Component.getRTTIDecl()->printQualifiedName(Out);
1945  Out << " RTTI";
1946  break;
1947 
1949  const CXXMethodDecl *MD = Component.getFunctionDecl();
1950 
1951  std::string Str =
1953  MD);
1954  Out << Str;
1955  if (MD->isPure())
1956  Out << " [pure]";
1957 
1958  if (MD->isDeleted())
1959  Out << " [deleted]";
1960 
1961  ThunkInfo Thunk = VTableThunks.lookup(I);
1962  if (!Thunk.isEmpty()) {
1963  // If this function pointer has a return adjustment, dump it.
1964  if (!Thunk.Return.isEmpty()) {
1965  Out << "\n [return adjustment: ";
1966  Out << Thunk.Return.NonVirtual << " non-virtual";
1967 
1969  Out << ", " << Thunk.Return.Virtual.Itanium.VBaseOffsetOffset;
1970  Out << " vbase offset offset";
1971  }
1972 
1973  Out << ']';
1974  }
1975 
1976  // If this function pointer has a 'this' pointer adjustment, dump it.
1977  if (!Thunk.This.isEmpty()) {
1978  Out << "\n [this adjustment: ";
1979  Out << Thunk.This.NonVirtual << " non-virtual";
1980 
1981  if (Thunk.This.Virtual.Itanium.VCallOffsetOffset) {
1982  Out << ", " << Thunk.This.Virtual.Itanium.VCallOffsetOffset;
1983  Out << " vcall offset offset";
1984  }
1985 
1986  Out << ']';
1987  }
1988  }
1989 
1990  break;
1991  }
1992 
1995  bool IsComplete =
1997 
1998  const CXXDestructorDecl *DD = Component.getDestructorDecl();
1999 
2000  DD->printQualifiedName(Out);
2001  if (IsComplete)
2002  Out << "() [complete]";
2003  else
2004  Out << "() [deleting]";
2005 
2006  if (DD->isPure())
2007  Out << " [pure]";
2008 
2009  ThunkInfo Thunk = VTableThunks.lookup(I);
2010  if (!Thunk.isEmpty()) {
2011  // If this destructor has a 'this' pointer adjustment, dump it.
2012  if (!Thunk.This.isEmpty()) {
2013  Out << "\n [this adjustment: ";
2014  Out << Thunk.This.NonVirtual << " non-virtual";
2015 
2016  if (Thunk.This.Virtual.Itanium.VCallOffsetOffset) {
2017  Out << ", " << Thunk.This.Virtual.Itanium.VCallOffsetOffset;
2018  Out << " vcall offset offset";
2019  }
2020 
2021  Out << ']';
2022  }
2023  }
2024 
2025  break;
2026  }
2027 
2029  const CXXMethodDecl *MD = Component.getUnusedFunctionDecl();
2030 
2031  std::string Str =
2033  MD);
2034  Out << "[unused] " << Str;
2035  if (MD->isPure())
2036  Out << " [pure]";
2037  }
2038 
2039  }
2040 
2041  Out << '\n';
2042 
2043  // Dump the next address point.
2044  uint64_t NextIndex = Index + 1;
2045  if (AddressPointsByIndex.count(NextIndex)) {
2046  if (AddressPointsByIndex.count(NextIndex) == 1) {
2047  const BaseSubobject &Base =
2048  AddressPointsByIndex.find(NextIndex)->second;
2049 
2050  Out << " -- (";
2051  Base.getBase()->printQualifiedName(Out);
2052  Out << ", " << Base.getBaseOffset().getQuantity();
2053  Out << ") vtable address --\n";
2054  } else {
2055  CharUnits BaseOffset =
2056  AddressPointsByIndex.lower_bound(NextIndex)->second.getBaseOffset();
2057 
2058  // We store the class names in a set to get a stable order.
2059  std::set<std::string> ClassNames;
2060  for (const auto &I :
2061  llvm::make_range(AddressPointsByIndex.equal_range(NextIndex))) {
2062  assert(I.second.getBaseOffset() == BaseOffset &&
2063  "Invalid base offset!");
2064  const CXXRecordDecl *RD = I.second.getBase();
2065  ClassNames.insert(RD->getQualifiedNameAsString());
2066  }
2067 
2068  for (const std::string &Name : ClassNames) {
2069  Out << " -- (" << Name;
2070  Out << ", " << BaseOffset.getQuantity() << ") vtable address --\n";
2071  }
2072  }
2073  }
2074  }
2075 
2076  Out << '\n';
2077 
2078  if (isBuildingConstructorVTable())
2079  return;
2080 
2081  if (MostDerivedClass->getNumVBases()) {
2082  // We store the virtual base class names and their offsets in a map to get
2083  // a stable order.
2084 
2085  std::map<std::string, CharUnits> ClassNamesAndOffsets;
2086  for (const auto &I : VBaseOffsetOffsets) {
2087  std::string ClassName = I.first->getQualifiedNameAsString();
2088  CharUnits OffsetOffset = I.second;
2089  ClassNamesAndOffsets.insert(std::make_pair(ClassName, OffsetOffset));
2090  }
2091 
2092  Out << "Virtual base offset offsets for '";
2093  MostDerivedClass->printQualifiedName(Out);
2094  Out << "' (";
2095  Out << ClassNamesAndOffsets.size();
2096  Out << (ClassNamesAndOffsets.size() == 1 ? " entry" : " entries") << ").\n";
2097 
2098  for (const auto &I : ClassNamesAndOffsets)
2099  Out << " " << I.first << " | " << I.second.getQuantity() << '\n';
2100 
2101  Out << "\n";
2102  }
2103 
2104  if (!Thunks.empty()) {
2105  // We store the method names in a map to get a stable order.
2106  std::map<std::string, const CXXMethodDecl *> MethodNamesAndDecls;
2107 
2108  for (const auto &I : Thunks) {
2109  const CXXMethodDecl *MD = I.first;
2110  std::string MethodName =
2112  MD);
2113 
2114  MethodNamesAndDecls.insert(std::make_pair(MethodName, MD));
2115  }
2116 
2117  for (const auto &I : MethodNamesAndDecls) {
2118  const std::string &MethodName = I.first;
2119  const CXXMethodDecl *MD = I.second;
2120 
2121  ThunkInfoVectorTy ThunksVector = Thunks[MD];
2122  llvm::sort(ThunksVector, [](const ThunkInfo &LHS, const ThunkInfo &RHS) {
2123  assert(LHS.Method == nullptr && RHS.Method == nullptr);
2124  return std::tie(LHS.This, LHS.Return) < std::tie(RHS.This, RHS.Return);
2125  });
2126 
2127  Out << "Thunks for '" << MethodName << "' (" << ThunksVector.size();
2128  Out << (ThunksVector.size() == 1 ? " entry" : " entries") << ").\n";
2129 
2130  for (unsigned I = 0, E = ThunksVector.size(); I != E; ++I) {
2131  const ThunkInfo &Thunk = ThunksVector[I];
2132 
2133  Out << llvm::format("%4d | ", I);
2134 
2135  // If this function pointer has a return pointer adjustment, dump it.
2136  if (!Thunk.Return.isEmpty()) {
2137  Out << "return adjustment: " << Thunk.Return.NonVirtual;
2138  Out << " non-virtual";
2140  Out << ", " << Thunk.Return.Virtual.Itanium.VBaseOffsetOffset;
2141  Out << " vbase offset offset";
2142  }
2143 
2144  if (!Thunk.This.isEmpty())
2145  Out << "\n ";
2146  }
2147 
2148  // If this function pointer has a 'this' pointer adjustment, dump it.
2149  if (!Thunk.This.isEmpty()) {
2150  Out << "this adjustment: ";
2151  Out << Thunk.This.NonVirtual << " non-virtual";
2152 
2153  if (Thunk.This.Virtual.Itanium.VCallOffsetOffset) {
2154  Out << ", " << Thunk.This.Virtual.Itanium.VCallOffsetOffset;
2155  Out << " vcall offset offset";
2156  }
2157  }
2158 
2159  Out << '\n';
2160  }
2161 
2162  Out << '\n';
2163  }
2164  }
2165 
2166  // Compute the vtable indices for all the member functions.
2167  // Store them in a map keyed by the index so we'll get a sorted table.
2168  std::map<uint64_t, std::string> IndicesMap;
2169 
2170  for (const auto *MD : MostDerivedClass->methods()) {
2171  // We only want virtual member functions.
2173  continue;
2174  MD = MD->getCanonicalDecl();
2175 
2176  std::string MethodName =
2178  MD);
2179 
2180  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
2181  GlobalDecl GD(DD, Dtor_Complete);
2182  assert(MethodVTableIndices.count(GD));
2183  uint64_t VTableIndex = MethodVTableIndices[GD];
2184  IndicesMap[VTableIndex] = MethodName + " [complete]";
2185  IndicesMap[VTableIndex + 1] = MethodName + " [deleting]";
2186  } else {
2187  assert(MethodVTableIndices.count(MD));
2188  IndicesMap[MethodVTableIndices[MD]] = MethodName;
2189  }
2190  }
2191 
2192  // Print the vtable indices for all the member functions.
2193  if (!IndicesMap.empty()) {
2194  Out << "VTable indices for '";
2195  MostDerivedClass->printQualifiedName(Out);
2196  Out << "' (" << IndicesMap.size() << " entries).\n";
2197 
2198  for (const auto &I : IndicesMap) {
2199  uint64_t VTableIndex = I.first;
2200  const std::string &MethodName = I.second;
2201 
2202  Out << llvm::format("%4" PRIu64 " | ", VTableIndex) << MethodName
2203  << '\n';
2204  }
2205  }
2206 
2207  Out << '\n';
2208 }
2209 }
2210 
2213  unsigned numVTables) {
2214  VTableLayout::AddressPointsIndexMapTy indexMap(numVTables);
2215 
2216  for (auto it = addressPoints.begin(); it != addressPoints.end(); ++it) {
2217  const auto &addressPointLoc = it->second;
2218  unsigned vtableIndex = addressPointLoc.VTableIndex;
2219  unsigned addressPoint = addressPointLoc.AddressPointIndex;
2220  if (indexMap[vtableIndex]) {
2221  // Multiple BaseSubobjects can map to the same AddressPointLocation, but
2222  // every vtable index should have a unique address point.
2223  assert(indexMap[vtableIndex] == addressPoint &&
2224  "Every vtable index should have a unique address point. Found a "
2225  "vtable that has two different address points.");
2226  } else {
2227  indexMap[vtableIndex] = addressPoint;
2228  }
2229  }
2230 
2231  // Note that by this point, not all the address may be initialized if the
2232  // AddressPoints map is empty. This is ok if the map isn't needed. See
2233  // MicrosoftVTableContext::computeVTableRelatedInformation() which uses an
2234  // emprt map.
2235  return indexMap;
2236 }
2237 
2239  ArrayRef<VTableComponent> VTableComponents,
2240  ArrayRef<VTableThunkTy> VTableThunks,
2241  const AddressPointsMapTy &AddressPoints)
2242  : VTableComponents(VTableComponents), VTableThunks(VTableThunks),
2243  AddressPoints(AddressPoints), AddressPointIndices(MakeAddressPointIndices(
2244  AddressPoints, VTableIndices.size())) {
2245  if (VTableIndices.size() <= 1)
2246  assert(VTableIndices.size() == 1 && VTableIndices[0] == 0);
2247  else
2248  this->VTableIndices = OwningArrayRef<size_t>(VTableIndices);
2249 
2250  llvm::sort(this->VTableThunks, [](const VTableLayout::VTableThunkTy &LHS,
2251  const VTableLayout::VTableThunkTy &RHS) {
2252  assert((LHS.first != RHS.first || LHS.second == RHS.second) &&
2253  "Different thunks should have unique indices!");
2254  return LHS.first < RHS.first;
2255  });
2256 }
2257 
2259 
2261  return MD->isVirtual() && !MD->isConsteval();
2262 }
2263 
2265  ASTContext &Context, VTableComponentLayout ComponentLayout)
2266  : VTableContextBase(/*MS=*/false), ComponentLayout(ComponentLayout) {}
2267 
2269 
2271  GD = GD.getCanonicalDecl();
2272  MethodVTableIndicesTy::iterator I = MethodVTableIndices.find(GD);
2273  if (I != MethodVTableIndices.end())
2274  return I->second;
2275 
2276  const CXXRecordDecl *RD = cast<CXXMethodDecl>(GD.getDecl())->getParent();
2277 
2278  computeVTableRelatedInformation(RD);
2279 
2280  I = MethodVTableIndices.find(GD);
2281  assert(I != MethodVTableIndices.end() && "Did not find index!");
2282  return I->second;
2283 }
2284 
2285 CharUnits
2287  const CXXRecordDecl *VBase) {
2288  ClassPairTy ClassPair(RD, VBase);
2289 
2290  VirtualBaseClassOffsetOffsetsMapTy::iterator I =
2291  VirtualBaseClassOffsetOffsets.find(ClassPair);
2292  if (I != VirtualBaseClassOffsetOffsets.end())
2293  return I->second;
2294 
2295  VCallAndVBaseOffsetBuilder Builder(*this, RD, RD, /*Overriders=*/nullptr,
2297  /*BaseIsVirtual=*/false,
2298  /*OffsetInLayoutClass=*/CharUnits::Zero());
2299 
2300  for (const auto &I : Builder.getVBaseOffsetOffsets()) {
2301  // Insert all types.
2302  ClassPairTy ClassPair(RD, I.first);
2303 
2304  VirtualBaseClassOffsetOffsets.insert(std::make_pair(ClassPair, I.second));
2305  }
2306 
2307  I = VirtualBaseClassOffsetOffsets.find(ClassPair);
2308  assert(I != VirtualBaseClassOffsetOffsets.end() && "Did not find index!");
2309 
2310  return I->second;
2311 }
2312 
2313 static std::unique_ptr<VTableLayout>
2314 CreateVTableLayout(const ItaniumVTableBuilder &Builder) {
2316  VTableThunks(Builder.vtable_thunks_begin(), Builder.vtable_thunks_end());
2317 
2318  return std::make_unique<VTableLayout>(
2319  Builder.VTableIndices, Builder.vtable_components(), VTableThunks,
2320  Builder.getAddressPoints());
2321 }
2322 
2323 void
2324 ItaniumVTableContext::computeVTableRelatedInformation(const CXXRecordDecl *RD) {
2325  std::unique_ptr<const VTableLayout> &Entry = VTableLayouts[RD];
2326 
2327  // Check if we've computed this information before.
2328  if (Entry)
2329  return;
2330 
2331  ItaniumVTableBuilder Builder(*this, RD, CharUnits::Zero(),
2332  /*MostDerivedClassIsVirtual=*/false, RD);
2333  Entry = CreateVTableLayout(Builder);
2334 
2335  MethodVTableIndices.insert(Builder.vtable_indices_begin(),
2336  Builder.vtable_indices_end());
2337 
2338  // Add the known thunks.
2339  Thunks.insert(Builder.thunks_begin(), Builder.thunks_end());
2340 
2341  // If we don't have the vbase information for this class, insert it.
2342  // getVirtualBaseOffsetOffset will compute it separately without computing
2343  // the rest of the vtable related information.
2344  if (!RD->getNumVBases())
2345  return;
2346 
2347  const CXXRecordDecl *VBase =
2349 
2350  if (VirtualBaseClassOffsetOffsets.count(std::make_pair(RD, VBase)))
2351  return;
2352 
2353  for (const auto &I : Builder.getVBaseOffsetOffsets()) {
2354  // Insert all types.
2355  ClassPairTy ClassPair(RD, I.first);
2356 
2357  VirtualBaseClassOffsetOffsets.insert(std::make_pair(ClassPair, I.second));
2358  }
2359 }
2360 
2361 std::unique_ptr<VTableLayout>
2363  const CXXRecordDecl *MostDerivedClass, CharUnits MostDerivedClassOffset,
2364  bool MostDerivedClassIsVirtual, const CXXRecordDecl *LayoutClass) {
2365  ItaniumVTableBuilder Builder(*this, MostDerivedClass, MostDerivedClassOffset,
2366  MostDerivedClassIsVirtual, LayoutClass);
2367  return CreateVTableLayout(Builder);
2368 }
2369 
2370 namespace {
2371 
2372 // Vtables in the Microsoft ABI are different from the Itanium ABI.
2373 //
2374 // The main differences are:
2375 // 1. Separate vftable and vbtable.
2376 //
2377 // 2. Each subobject with a vfptr gets its own vftable rather than an address
2378 // point in a single vtable shared between all the subobjects.
2379 // Each vftable is represented by a separate section and virtual calls
2380 // must be done using the vftable which has a slot for the function to be
2381 // called.
2382 //
2383 // 3. Virtual method definitions expect their 'this' parameter to point to the
2384 // first vfptr whose table provides a compatible overridden method. In many
2385 // cases, this permits the original vf-table entry to directly call
2386 // the method instead of passing through a thunk.
2387 // See example before VFTableBuilder::ComputeThisOffset below.
2388 //
2389 // A compatible overridden method is one which does not have a non-trivial
2390 // covariant-return adjustment.
2391 //
2392 // The first vfptr is the one with the lowest offset in the complete-object
2393 // layout of the defining class, and the method definition will subtract
2394 // that constant offset from the parameter value to get the real 'this'
2395 // value. Therefore, if the offset isn't really constant (e.g. if a virtual
2396 // function defined in a virtual base is overridden in a more derived
2397 // virtual base and these bases have a reverse order in the complete
2398 // object), the vf-table may require a this-adjustment thunk.
2399 //
2400 // 4. vftables do not contain new entries for overrides that merely require
2401 // this-adjustment. Together with #3, this keeps vf-tables smaller and
2402 // eliminates the need for this-adjustment thunks in many cases, at the cost
2403 // of often requiring redundant work to adjust the "this" pointer.
2404 //
2405 // 5. Instead of VTT and constructor vtables, vbtables and vtordisps are used.
2406 // Vtordisps are emitted into the class layout if a class has
2407 // a) a user-defined ctor/dtor
2408 // and
2409 // b) a method overriding a method in a virtual base.
2410 //
2411 // To get a better understanding of this code,
2412 // you might want to see examples in test/CodeGenCXX/microsoft-abi-vtables-*.cpp
2413 
2414 class VFTableBuilder {
2415 public:
2416  typedef llvm::DenseMap<GlobalDecl, MethodVFTableLocation>
2417  MethodVFTableLocationsTy;
2418 
2419  typedef llvm::iterator_range<MethodVFTableLocationsTy::const_iterator>
2420  method_locations_range;
2421 
2422 private:
2423  /// VTables - Global vtable information.
2424  MicrosoftVTableContext &VTables;
2425 
2426  /// Context - The ASTContext which we will use for layout information.
2427  ASTContext &Context;
2428 
2429  /// MostDerivedClass - The most derived class for which we're building this
2430  /// vtable.
2431  const CXXRecordDecl *MostDerivedClass;
2432 
2433  const ASTRecordLayout &MostDerivedClassLayout;
2434 
2435  const VPtrInfo &WhichVFPtr;
2436 
2437  /// FinalOverriders - The final overriders of the most derived class.
2438  const FinalOverriders Overriders;
2439 
2440  /// Components - The components of the vftable being built.
2442 
2443  MethodVFTableLocationsTy MethodVFTableLocations;
2444 
2445  /// Does this class have an RTTI component?
2446  bool HasRTTIComponent = false;
2447 
2448  /// MethodInfo - Contains information about a method in a vtable.
2449  /// (Used for computing 'this' pointer adjustment thunks.
2450  struct MethodInfo {
2451  /// VBTableIndex - The nonzero index in the vbtable that
2452  /// this method's base has, or zero.
2453  const uint64_t VBTableIndex;
2454 
2455  /// VFTableIndex - The index in the vftable that this method has.
2456  const uint64_t VFTableIndex;
2457 
2458  /// Shadowed - Indicates if this vftable slot is shadowed by
2459  /// a slot for a covariant-return override. If so, it shouldn't be printed
2460  /// or used for vcalls in the most derived class.
2461  bool Shadowed;
2462 
2463  /// UsesExtraSlot - Indicates if this vftable slot was created because
2464  /// any of the overridden slots required a return adjusting thunk.
2465  bool UsesExtraSlot;
2466 
2467  MethodInfo(uint64_t VBTableIndex, uint64_t VFTableIndex,
2468  bool UsesExtraSlot = false)
2469  : VBTableIndex(VBTableIndex), VFTableIndex(VFTableIndex),
2470  Shadowed(false), UsesExtraSlot(UsesExtraSlot) {}
2471 
2472  MethodInfo()
2473  : VBTableIndex(0), VFTableIndex(0), Shadowed(false),
2474  UsesExtraSlot(false) {}
2475  };
2476 
2477  typedef llvm::DenseMap<const CXXMethodDecl *, MethodInfo> MethodInfoMapTy;
2478 
2479  /// MethodInfoMap - The information for all methods in the vftable we're
2480  /// currently building.
2481  MethodInfoMapTy MethodInfoMap;
2482 
2483  typedef llvm::DenseMap<uint64_t, ThunkInfo> VTableThunksMapTy;
2484 
2485  /// VTableThunks - The thunks by vftable index in the vftable currently being
2486  /// built.
2487  VTableThunksMapTy VTableThunks;
2488 
2489  typedef SmallVector<ThunkInfo, 1> ThunkInfoVectorTy;
2490  typedef llvm::DenseMap<const CXXMethodDecl *, ThunkInfoVectorTy> ThunksMapTy;
2491 
2492  /// Thunks - A map that contains all the thunks needed for all methods in the
2493  /// most derived class for which the vftable is currently being built.
2494  ThunksMapTy Thunks;
2495 
2496  /// AddThunk - Add a thunk for the given method.
2497  void AddThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk) {
2498  SmallVector<ThunkInfo, 1> &ThunksVector = Thunks[MD];
2499 
2500  // Check if we have this thunk already.
2501  if (llvm::is_contained(ThunksVector, Thunk))
2502  return;
2503 
2504  ThunksVector.push_back(Thunk);
2505  }
2506 
2507  /// ComputeThisOffset - Returns the 'this' argument offset for the given
2508  /// method, relative to the beginning of the MostDerivedClass.
2509  CharUnits ComputeThisOffset(FinalOverriders::OverriderInfo Overrider);
2510 
2511  void CalculateVtordispAdjustment(FinalOverriders::OverriderInfo Overrider,
2512  CharUnits ThisOffset, ThisAdjustment &TA);
2513 
2514  /// AddMethod - Add a single virtual member function to the vftable
2515  /// components vector.
2516  void AddMethod(const CXXMethodDecl *MD, ThunkInfo TI) {
2517  if (!TI.isEmpty()) {
2518  VTableThunks[Components.size()] = TI;
2519  AddThunk(MD, TI);
2520  }
2521  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
2522  assert(TI.Return.isEmpty() &&
2523  "Destructor can't have return adjustment!");
2524  Components.push_back(VTableComponent::MakeDeletingDtor(DD));
2525  } else {
2526  Components.push_back(VTableComponent::MakeFunction(MD));
2527  }
2528  }
2529 
2530  /// AddMethods - Add the methods of this base subobject and the relevant
2531  /// subbases to the vftable we're currently laying out.
2532  void AddMethods(BaseSubobject Base, unsigned BaseDepth,
2533  const CXXRecordDecl *LastVBase,
2534  BasesSetVectorTy &VisitedBases);
2535 
2536  void LayoutVFTable() {
2537  // RTTI data goes before all other entries.
2538  if (HasRTTIComponent)
2539  Components.push_back(VTableComponent::MakeRTTI(MostDerivedClass));
2540 
2541  BasesSetVectorTy VisitedBases;
2542  AddMethods(BaseSubobject(MostDerivedClass, CharUnits::Zero()), 0, nullptr,
2543  VisitedBases);
2544  // Note that it is possible for the vftable to contain only an RTTI
2545  // pointer, if all virtual functions are constewval.
2546  assert(!Components.empty() && "vftable can't be empty");
2547 
2548  assert(MethodVFTableLocations.empty());
2549  for (const auto &I : MethodInfoMap) {
2550  const CXXMethodDecl *MD = I.first;
2551  const MethodInfo &MI = I.second;
2552  assert(MD == MD->getCanonicalDecl());
2553 
2554  // Skip the methods that the MostDerivedClass didn't override
2555  // and the entries shadowed by return adjusting thunks.
2556  if (MD->getParent() != MostDerivedClass || MI.Shadowed)
2557  continue;
2558  MethodVFTableLocation Loc(MI.VBTableIndex, WhichVFPtr.getVBaseWithVPtr(),
2559  WhichVFPtr.NonVirtualOffset, MI.VFTableIndex);
2560  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
2561  MethodVFTableLocations[GlobalDecl(DD, Dtor_Deleting)] = Loc;
2562  } else {
2563  MethodVFTableLocations[MD] = Loc;
2564  }
2565  }
2566  }
2567 
2568 public:
2569  VFTableBuilder(MicrosoftVTableContext &VTables,
2570  const CXXRecordDecl *MostDerivedClass, const VPtrInfo &Which)
2571  : VTables(VTables),
2572  Context(MostDerivedClass->getASTContext()),
2573  MostDerivedClass(MostDerivedClass),
2574  MostDerivedClassLayout(Context.getASTRecordLayout(MostDerivedClass)),
2575  WhichVFPtr(Which),
2576  Overriders(MostDerivedClass, CharUnits(), MostDerivedClass) {
2577  // Provide the RTTI component if RTTIData is enabled. If the vftable would
2578  // be available externally, we should not provide the RTTI componenent. It
2579  // is currently impossible to get available externally vftables with either
2580  // dllimport or extern template instantiations, but eventually we may add a
2581  // flag to support additional devirtualization that needs this.
2582  if (Context.getLangOpts().RTTIData)
2583  HasRTTIComponent = true;
2584 
2585  LayoutVFTable();
2586 
2587  if (Context.getLangOpts().DumpVTableLayouts)
2588  dumpLayout(llvm::outs());
2589  }
2590 
2591  uint64_t getNumThunks() const { return Thunks.size(); }
2592 
2593  ThunksMapTy::const_iterator thunks_begin() const { return Thunks.begin(); }
2594 
2595  ThunksMapTy::const_iterator thunks_end() const { return Thunks.end(); }
2596 
2597  method_locations_range vtable_locations() const {
2598  return method_locations_range(MethodVFTableLocations.begin(),
2599  MethodVFTableLocations.end());
2600  }
2601 
2602  ArrayRef<VTableComponent> vtable_components() const { return Components; }
2603 
2604  VTableThunksMapTy::const_iterator vtable_thunks_begin() const {
2605  return VTableThunks.begin();
2606  }
2607 
2608  VTableThunksMapTy::const_iterator vtable_thunks_end() const {
2609  return VTableThunks.end();
2610  }
2611 
2612  void dumpLayout(raw_ostream &);
2613 };
2614 
2615 } // end namespace
2616 
2617 // Let's study one class hierarchy as an example:
2618 // struct A {
2619 // virtual void f();
2620 // int x;
2621 // };
2622 //
2623 // struct B : virtual A {
2624 // virtual void f();
2625 // };
2626 //
2627 // Record layouts:
2628 // struct A:
2629 // 0 | (A vftable pointer)
2630 // 4 | int x
2631 //
2632 // struct B:
2633 // 0 | (B vbtable pointer)
2634 // 4 | struct A (virtual base)
2635 // 4 | (A vftable pointer)
2636 // 8 | int x
2637 //
2638 // Let's assume we have a pointer to the A part of an object of dynamic type B:
2639 // B b;
2640 // A *a = (A*)&b;
2641 // a->f();
2642 //
2643 // In this hierarchy, f() belongs to the vftable of A, so B::f() expects
2644 // "this" parameter to point at the A subobject, which is B+4.
2645 // In the B::f() prologue, it adjusts "this" back to B by subtracting 4,
2646 // performed as a *static* adjustment.
2647 //
2648 // Interesting thing happens when we alter the relative placement of A and B
2649 // subobjects in a class:
2650 // struct C : virtual B { };
2651 //
2652 // C c;
2653 // A *a = (A*)&c;
2654 // a->f();
2655 //
2656 // Respective record layout is:
2657 // 0 | (C vbtable pointer)
2658 // 4 | struct A (virtual base)
2659 // 4 | (A vftable pointer)
2660 // 8 | int x
2661 // 12 | struct B (virtual base)
2662 // 12 | (B vbtable pointer)
2663 //
2664 // The final overrider of f() in class C is still B::f(), so B+4 should be
2665 // passed as "this" to that code. However, "a" points at B-8, so the respective
2666 // vftable entry should hold a thunk that adds 12 to the "this" argument before
2667 // performing a tail call to B::f().
2668 //
2669 // With this example in mind, we can now calculate the 'this' argument offset
2670 // for the given method, relative to the beginning of the MostDerivedClass.
2671 CharUnits
2672 VFTableBuilder::ComputeThisOffset(FinalOverriders::OverriderInfo Overrider) {
2673  BasesSetVectorTy Bases;
2674 
2675  {
2676  // Find the set of least derived bases that define the given method.
2677  OverriddenMethodsSetTy VisitedOverriddenMethods;
2678  auto InitialOverriddenDefinitionCollector = [&](
2679  const CXXMethodDecl *OverriddenMD) {
2680  if (OverriddenMD->size_overridden_methods() == 0)
2681  Bases.insert(OverriddenMD->getParent());
2682  // Don't recurse on this method if we've already collected it.
2683  return VisitedOverriddenMethods.insert(OverriddenMD).second;
2684  };
2685  visitAllOverriddenMethods(Overrider.Method,
2686  InitialOverriddenDefinitionCollector);
2687  }
2688 
2689  // If there are no overrides then 'this' is located
2690  // in the base that defines the method.
2691  if (Bases.size() == 0)
2692  return Overrider.Offset;
2693 
2694  CXXBasePaths Paths;
2695  Overrider.Method->getParent()->lookupInBases(
2696  [&Bases](const CXXBaseSpecifier *Specifier, CXXBasePath &) {
2697  return Bases.count(Specifier->getType()->getAsCXXRecordDecl());
2698  },
2699  Paths);
2700 
2701  // This will hold the smallest this offset among overridees of MD.
2702  // This implies that an offset of a non-virtual base will dominate an offset
2703  // of a virtual base to potentially reduce the number of thunks required
2704  // in the derived classes that inherit this method.
2705  CharUnits Ret;
2706  bool First = true;
2707 
2708  const ASTRecordLayout &OverriderRDLayout =
2709  Context.getASTRecordLayout(Overrider.Method->getParent());
2710  for (const CXXBasePath &Path : Paths) {
2711  CharUnits ThisOffset = Overrider.Offset;
2712  CharUnits LastVBaseOffset;
2713 
2714  // For each path from the overrider to the parents of the overridden
2715  // methods, traverse the path, calculating the this offset in the most
2716  // derived class.
2717  for (const CXXBasePathElement &Element : Path) {
2718  QualType CurTy = Element.Base->getType();
2719  const CXXRecordDecl *PrevRD = Element.Class,
2720  *CurRD = CurTy->getAsCXXRecordDecl();
2721  const ASTRecordLayout &Layout = Context.getASTRecordLayout(PrevRD);
2722 
2723  if (Element.Base->isVirtual()) {
2724  // The interesting things begin when you have virtual inheritance.
2725  // The final overrider will use a static adjustment equal to the offset
2726  // of the vbase in the final overrider class.
2727  // For example, if the final overrider is in a vbase B of the most
2728  // derived class and it overrides a method of the B's own vbase A,
2729  // it uses A* as "this". In its prologue, it can cast A* to B* with
2730  // a static offset. This offset is used regardless of the actual
2731  // offset of A from B in the most derived class, requiring an
2732  // this-adjusting thunk in the vftable if A and B are laid out
2733  // differently in the most derived class.
2734  LastVBaseOffset = ThisOffset =
2735  Overrider.Offset + OverriderRDLayout.getVBaseClassOffset(CurRD);
2736  } else {
2737  ThisOffset += Layout.getBaseClassOffset(CurRD);
2738  }
2739  }
2740 
2741  if (isa<CXXDestructorDecl>(Overrider.Method)) {
2742  if (LastVBaseOffset.isZero()) {
2743  // If a "Base" class has at least one non-virtual base with a virtual
2744  // destructor, the "Base" virtual destructor will take the address
2745  // of the "Base" subobject as the "this" argument.
2746  ThisOffset = Overrider.Offset;
2747  } else {
2748  // A virtual destructor of a virtual base takes the address of the
2749  // virtual base subobject as the "this" argument.
2750  ThisOffset = LastVBaseOffset;
2751  }
2752  }
2753 
2754  if (Ret > ThisOffset || First) {
2755  First = false;
2756  Ret = ThisOffset;
2757  }
2758  }
2759 
2760  assert(!First && "Method not found in the given subobject?");
2761  return Ret;
2762 }
2763 
2764 // Things are getting even more complex when the "this" adjustment has to
2765 // use a dynamic offset instead of a static one, or even two dynamic offsets.
2766 // This is sometimes required when a virtual call happens in the middle of
2767 // a non-most-derived class construction or destruction.
2768 //
2769 // Let's take a look at the following example:
2770 // struct A {
2771 // virtual void f();
2772 // };
2773 //
2774 // void foo(A *a) { a->f(); } // Knows nothing about siblings of A.
2775 //
2776 // struct B : virtual A {
2777 // virtual void f();
2778 // B() {
2779 // foo(this);
2780 // }
2781 // };
2782 //
2783 // struct C : virtual B {
2784 // virtual void f();
2785 // };
2786 //
2787 // Record layouts for these classes are:
2788 // struct A
2789 // 0 | (A vftable pointer)
2790 //
2791 // struct B
2792 // 0 | (B vbtable pointer)
2793 // 4 | (vtordisp for vbase A)
2794 // 8 | struct A (virtual base)
2795 // 8 | (A vftable pointer)
2796 //
2797 // struct C
2798 // 0 | (C vbtable pointer)
2799 // 4 | (vtordisp for vbase A)
2800 // 8 | struct A (virtual base) // A precedes B!
2801 // 8 | (A vftable pointer)
2802 // 12 | struct B (virtual base)
2803 // 12 | (B vbtable pointer)
2804 //
2805 // When one creates an object of type C, the C constructor:
2806 // - initializes all the vbptrs, then
2807 // - calls the A subobject constructor
2808 // (initializes A's vfptr with an address of A vftable), then
2809 // - calls the B subobject constructor
2810 // (initializes A's vfptr with an address of B vftable and vtordisp for A),
2811 // that in turn calls foo(), then
2812 // - initializes A's vfptr with an address of C vftable and zeroes out the
2813 // vtordisp
2814 // FIXME: if a structor knows it belongs to MDC, why doesn't it use a vftable
2815 // without vtordisp thunks?
2816 // FIXME: how are vtordisp handled in the presence of nooverride/final?
2817 //
2818 // When foo() is called, an object with a layout of class C has a vftable
2819 // referencing B::f() that assumes a B layout, so the "this" adjustments are
2820 // incorrect, unless an extra adjustment is done. This adjustment is called
2821 // "vtordisp adjustment". Vtordisp basically holds the difference between the
2822 // actual location of a vbase in the layout class and the location assumed by
2823 // the vftable of the class being constructed/destructed. Vtordisp is only
2824 // needed if "this" escapes a
2825 // structor (or we can't prove otherwise).
2826 // [i.e. vtordisp is a dynamic adjustment for a static adjustment, which is an
2827 // estimation of a dynamic adjustment]
2828 //
2829 // foo() gets a pointer to the A vbase and doesn't know anything about B or C,
2830 // so it just passes that pointer as "this" in a virtual call.
2831 // If there was no vtordisp, that would just dispatch to B::f().
2832 // However, B::f() assumes B+8 is passed as "this",
2833 // yet the pointer foo() passes along is B-4 (i.e. C+8).
2834 // An extra adjustment is needed, so we emit a thunk into the B vftable.
2835 // This vtordisp thunk subtracts the value of vtordisp
2836 // from the "this" argument (-12) before making a tailcall to B::f().
2837 //
2838 // Let's consider an even more complex example:
2839 // struct D : virtual B, virtual C {
2840 // D() {
2841 // foo(this);
2842 // }
2843 // };
2844 //
2845 // struct D
2846 // 0 | (D vbtable pointer)
2847 // 4 | (vtordisp for vbase A)
2848 // 8 | struct A (virtual base) // A precedes both B and C!
2849 // 8 | (A vftable pointer)
2850 // 12 | struct B (virtual base) // B precedes C!
2851 // 12 | (B vbtable pointer)
2852 // 16 | struct C (virtual base)
2853 // 16 | (C vbtable pointer)
2854 //
2855 // When D::D() calls foo(), we find ourselves in a thunk that should tailcall
2856 // to C::f(), which assumes C+8 as its "this" parameter. This time, foo()
2857 // passes along A, which is C-8. The A vtordisp holds
2858 // "D.vbptr[index_of_A] - offset_of_A_in_D"
2859 // and we statically know offset_of_A_in_D, so can get a pointer to D.
2860 // When we know it, we can make an extra vbtable lookup to locate the C vbase
2861 // and one extra static adjustment to calculate the expected value of C+8.
2862 void VFTableBuilder::CalculateVtordispAdjustment(
2863  FinalOverriders::OverriderInfo Overrider, CharUnits ThisOffset,
2864  ThisAdjustment &TA) {
2865  const ASTRecordLayout::VBaseOffsetsMapTy &VBaseMap =
2866  MostDerivedClassLayout.getVBaseOffsetsMap();
2867  const ASTRecordLayout::VBaseOffsetsMapTy::const_iterator &VBaseMapEntry =
2868  VBaseMap.find(WhichVFPtr.getVBaseWithVPtr());
2869  assert(VBaseMapEntry != VBaseMap.end());
2870 
2871  // If there's no vtordisp or the final overrider is defined in the same vbase
2872  // as the initial declaration, we don't need any vtordisp adjustment.
2873  if (!VBaseMapEntry->second.hasVtorDisp() ||
2874  Overrider.VirtualBase == WhichVFPtr.getVBaseWithVPtr())
2875  return;
2876 
2877  // OK, now we know we need to use a vtordisp thunk.
2878  // The implicit vtordisp field is located right before the vbase.
2879  CharUnits OffsetOfVBaseWithVFPtr = VBaseMapEntry->second.VBaseOffset;
2881  (OffsetOfVBaseWithVFPtr - WhichVFPtr.FullOffsetInMDC).getQuantity() - 4;
2882 
2883  // A simple vtordisp thunk will suffice if the final overrider is defined
2884  // in either the most derived class or its non-virtual base.
2885  if (Overrider.Method->getParent() == MostDerivedClass ||
2886  !Overrider.VirtualBase)
2887  return;
2888 
2889  // Otherwise, we need to do use the dynamic offset of the final overrider
2890  // in order to get "this" adjustment right.
2892  (OffsetOfVBaseWithVFPtr + WhichVFPtr.NonVirtualOffset -
2893  MostDerivedClassLayout.getVBPtrOffset()).getQuantity();
2895  Context.getTypeSizeInChars(Context.IntTy).getQuantity() *
2896  VTables.getVBTableIndex(MostDerivedClass, Overrider.VirtualBase);
2897 
2898  TA.NonVirtual = (ThisOffset - Overrider.Offset).getQuantity();
2899 }
2900 
2902  const CXXRecordDecl *RD,
2903  SmallVector<const CXXMethodDecl *, 10> &VirtualMethods) {
2904  // Put the virtual methods into VirtualMethods in the proper order:
2905  // 1) Group overloads by declaration name. New groups are added to the
2906  // vftable in the order of their first declarations in this class
2907  // (including overrides, non-virtual methods and any other named decl that
2908  // might be nested within the class).
2909  // 2) In each group, new overloads appear in the reverse order of declaration.
2910  typedef SmallVector<const CXXMethodDecl *, 1> MethodGroup;
2912  typedef llvm::DenseMap<DeclarationName, unsigned> VisitedGroupIndicesTy;
2913  VisitedGroupIndicesTy VisitedGroupIndices;
2914  for (const auto *D : RD->decls()) {
2915  const auto *ND = dyn_cast<NamedDecl>(D);
2916  if (!ND)
2917  continue;
2918  VisitedGroupIndicesTy::iterator J;
2919  bool Inserted;
2920  std::tie(J, Inserted) = VisitedGroupIndices.insert(
2921  std::make_pair(ND->getDeclName(), Groups.size()));
2922  if (Inserted)
2923  Groups.push_back(MethodGroup());
2924  if (const auto *MD = dyn_cast<CXXMethodDecl>(ND))
2926  Groups[J->second].push_back(MD->getCanonicalDecl());
2927  }
2928 
2929  for (const MethodGroup &Group : Groups)
2930  VirtualMethods.append(Group.rbegin(), Group.rend());
2931 }
2932 
2933 static bool isDirectVBase(const CXXRecordDecl *Base, const CXXRecordDecl *RD) {
2934  for (const auto &B : RD->bases()) {
2935  if (B.isVirtual() && B.getType()->getAsCXXRecordDecl() == Base)
2936  return true;
2937  }
2938  return false;
2939 }
2940 
2941 void VFTableBuilder::AddMethods(BaseSubobject Base, unsigned BaseDepth,
2942  const CXXRecordDecl *LastVBase,
2943  BasesSetVectorTy &VisitedBases) {
2944  const CXXRecordDecl *RD = Base.getBase();
2945  if (!RD->isPolymorphic())
2946  return;
2947 
2948  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
2949 
2950  // See if this class expands a vftable of the base we look at, which is either
2951  // the one defined by the vfptr base path or the primary base of the current
2952  // class.
2953  const CXXRecordDecl *NextBase = nullptr, *NextLastVBase = LastVBase;
2954  CharUnits NextBaseOffset;
2955  if (BaseDepth < WhichVFPtr.PathToIntroducingObject.size()) {
2956  NextBase = WhichVFPtr.PathToIntroducingObject[BaseDepth];
2957  if (isDirectVBase(NextBase, RD)) {
2958  NextLastVBase = NextBase;
2959  NextBaseOffset = MostDerivedClassLayout.getVBaseClassOffset(NextBase);
2960  } else {
2961  NextBaseOffset =
2962  Base.getBaseOffset() + Layout.getBaseClassOffset(NextBase);
2963  }
2964  } else if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
2965  assert(!Layout.isPrimaryBaseVirtual() &&
2966  "No primary virtual bases in this ABI");
2967  NextBase = PrimaryBase;
2968  NextBaseOffset = Base.getBaseOffset();
2969  }
2970 
2971  if (NextBase) {
2972  AddMethods(BaseSubobject(NextBase, NextBaseOffset), BaseDepth + 1,
2973  NextLastVBase, VisitedBases);
2974  if (!VisitedBases.insert(NextBase))
2975  llvm_unreachable("Found a duplicate primary base!");
2976  }
2977 
2979  // Put virtual methods in the proper order.
2980  GroupNewVirtualOverloads(RD, VirtualMethods);
2981 
2982  // Now go through all virtual member functions and add them to the current
2983  // vftable. This is done by
2984  // - replacing overridden methods in their existing slots, as long as they
2985  // don't require return adjustment; calculating This adjustment if needed.
2986  // - adding new slots for methods of the current base not present in any
2987  // sub-bases;
2988  // - adding new slots for methods that require Return adjustment.
2989  // We keep track of the methods visited in the sub-bases in MethodInfoMap.
2990  for (const CXXMethodDecl *MD : VirtualMethods) {
2991  FinalOverriders::OverriderInfo FinalOverrider =
2992  Overriders.getOverrider(MD, Base.getBaseOffset());
2993  const CXXMethodDecl *FinalOverriderMD = FinalOverrider.Method;
2994  const CXXMethodDecl *OverriddenMD =
2995  FindNearestOverriddenMethod(MD, VisitedBases);
2996 
2997  ThisAdjustment ThisAdjustmentOffset;
2998  bool ReturnAdjustingThunk = false, ForceReturnAdjustmentMangling = false;
2999  CharUnits ThisOffset = ComputeThisOffset(FinalOverrider);
3000  ThisAdjustmentOffset.NonVirtual =
3001  (ThisOffset - WhichVFPtr.FullOffsetInMDC).getQuantity();
3002  if ((OverriddenMD || FinalOverriderMD != MD) &&
3003  WhichVFPtr.getVBaseWithVPtr())
3004  CalculateVtordispAdjustment(FinalOverrider, ThisOffset,
3005  ThisAdjustmentOffset);
3006 
3007  unsigned VBIndex =
3008  LastVBase ? VTables.getVBTableIndex(MostDerivedClass, LastVBase) : 0;
3009 
3010  if (OverriddenMD) {
3011  // If MD overrides anything in this vftable, we need to update the
3012  // entries.
3013  MethodInfoMapTy::iterator OverriddenMDIterator =
3014  MethodInfoMap.find(OverriddenMD);
3015 
3016  // If the overridden method went to a different vftable, skip it.
3017  if (OverriddenMDIterator == MethodInfoMap.end())
3018  continue;
3019 
3020  MethodInfo &OverriddenMethodInfo = OverriddenMDIterator->second;
3021 
3022  VBIndex = OverriddenMethodInfo.VBTableIndex;
3023 
3024  // Let's check if the overrider requires any return adjustments.
3025  // We must create a new slot if the MD's return type is not trivially
3026  // convertible to the OverriddenMD's one.
3027  // Once a chain of method overrides adds a return adjusting vftable slot,
3028  // all subsequent overrides will also use an extra method slot.
3029  ReturnAdjustingThunk = !ComputeReturnAdjustmentBaseOffset(
3030  Context, MD, OverriddenMD).isEmpty() ||
3031  OverriddenMethodInfo.UsesExtraSlot;
3032 
3033  if (!ReturnAdjustingThunk) {
3034  // No return adjustment needed - just replace the overridden method info
3035  // with the current info.
3036  MethodInfo MI(VBIndex, OverriddenMethodInfo.VFTableIndex);
3037  MethodInfoMap.erase(OverriddenMDIterator);
3038 
3039  assert(!MethodInfoMap.count(MD) &&
3040  "Should not have method info for this method yet!");
3041  MethodInfoMap.insert(std::make_pair(MD, MI));
3042  continue;
3043  }
3044 
3045  // In case we need a return adjustment, we'll add a new slot for
3046  // the overrider. Mark the overridden method as shadowed by the new slot.
3047  OverriddenMethodInfo.Shadowed = true;
3048 
3049  // Force a special name mangling for a return-adjusting thunk
3050  // unless the method is the final overrider without this adjustment.
3051  ForceReturnAdjustmentMangling =
3052  !(MD == FinalOverriderMD && ThisAdjustmentOffset.isEmpty());
3053  } else if (Base.getBaseOffset() != WhichVFPtr.FullOffsetInMDC ||
3054  MD->size_overridden_methods()) {
3055  // Skip methods that don't belong to the vftable of the current class,
3056  // e.g. each method that wasn't seen in any of the visited sub-bases
3057  // but overrides multiple methods of other sub-bases.
3058  continue;
3059  }
3060 
3061  // If we got here, MD is a method not seen in any of the sub-bases or
3062  // it requires return adjustment. Insert the method info for this method.
3063  MethodInfo MI(VBIndex,
3064  HasRTTIComponent ? Components.size() - 1 : Components.size(),
3065  ReturnAdjustingThunk);
3066 
3067  assert(!MethodInfoMap.count(MD) &&
3068  "Should not have method info for this method yet!");
3069  MethodInfoMap.insert(std::make_pair(MD, MI));
3070 
3071  // Check if this overrider needs a return adjustment.
3072  // We don't want to do this for pure virtual member functions.
3073  BaseOffset ReturnAdjustmentOffset;
3075  if (!FinalOverriderMD->isPure()) {
3076  ReturnAdjustmentOffset =
3077  ComputeReturnAdjustmentBaseOffset(Context, FinalOverriderMD, MD);
3078  }
3079  if (!ReturnAdjustmentOffset.isEmpty()) {
3080  ForceReturnAdjustmentMangling = true;
3082  ReturnAdjustmentOffset.NonVirtualOffset.getQuantity();
3083  if (ReturnAdjustmentOffset.VirtualBase) {
3084  const ASTRecordLayout &DerivedLayout =
3085  Context.getASTRecordLayout(ReturnAdjustmentOffset.DerivedClass);
3087  DerivedLayout.getVBPtrOffset().getQuantity();
3089  VTables.getVBTableIndex(ReturnAdjustmentOffset.DerivedClass,
3090  ReturnAdjustmentOffset.VirtualBase);
3091  }
3092  }
3093 
3094  AddMethod(FinalOverriderMD,
3095  ThunkInfo(ThisAdjustmentOffset, ReturnAdjustment,
3096  ForceReturnAdjustmentMangling ? MD : nullptr));
3097  }
3098 }
3099 
3100 static void PrintBasePath(const VPtrInfo::BasePath &Path, raw_ostream &Out) {
3101  for (const CXXRecordDecl *Elem : llvm::reverse(Path)) {
3102  Out << "'";
3103  Elem->printQualifiedName(Out);
3104  Out << "' in ";
3105  }
3106 }
3107 
3108 static void dumpMicrosoftThunkAdjustment(const ThunkInfo &TI, raw_ostream &Out,
3109  bool ContinueFirstLine) {
3110  const ReturnAdjustment &R = TI.Return;
3111  bool Multiline = false;
3112  const char *LinePrefix = "\n ";
3113  if (!R.isEmpty() || TI.Method) {
3114  if (!ContinueFirstLine)
3115  Out << LinePrefix;
3116  Out << "[return adjustment (to type '"
3117  << TI.Method->getReturnType().getCanonicalType() << "'): ";
3119  Out << "vbptr at offset " << R.Virtual.Microsoft.VBPtrOffset << ", ";
3120  if (R.Virtual.Microsoft.VBIndex)
3121  Out << "vbase #" << R.Virtual.Microsoft.VBIndex << ", ";
3122  Out << R.NonVirtual << " non-virtual]";
3123  Multiline = true;
3124  }
3125 
3126  const ThisAdjustment &T = TI.This;
3127  if (!T.isEmpty()) {
3128  if (Multiline || !ContinueFirstLine)
3129  Out << LinePrefix;
3130  Out << "[this adjustment: ";
3131  if (!TI.This.Virtual.isEmpty()) {
3132  assert(T.Virtual.Microsoft.VtordispOffset < 0);
3133  Out << "vtordisp at " << T.Virtual.Microsoft.VtordispOffset << ", ";
3134  if (T.Virtual.Microsoft.VBPtrOffset) {
3135  Out << "vbptr at " << T.Virtual.Microsoft.VBPtrOffset
3136  << " to the left,";
3137  assert(T.Virtual.Microsoft.VBOffsetOffset > 0);
3138  Out << LinePrefix << " vboffset at "
3139  << T.Virtual.Microsoft.VBOffsetOffset << " in the vbtable, ";
3140  }
3141  }
3142  Out << T.NonVirtual << " non-virtual]";
3143  }
3144 }
3145 
3146 void VFTableBuilder::dumpLayout(raw_ostream &Out) {
3147  Out << "VFTable for ";
3148  PrintBasePath(WhichVFPtr.PathToIntroducingObject, Out);
3149  Out << "'";
3150  MostDerivedClass->printQualifiedName(Out);
3151  Out << "' (" << Components.size()
3152  << (Components.size() == 1 ? " entry" : " entries") << ").\n";
3153 
3154  for (unsigned I = 0, E = Components.size(); I != E; ++I) {
3155  Out << llvm::format("%4d | ", I);
3156 
3157  const VTableComponent &Component = Components[I];
3158 
3159  // Dump the component.
3160  switch (Component.getKind()) {
3162  Component.getRTTIDecl()->printQualifiedName(Out);
3163  Out << " RTTI";
3164  break;
3165 
3167  const CXXMethodDecl *MD = Component.getFunctionDecl();
3168 
3169  // FIXME: Figure out how to print the real thunk type, since they can
3170  // differ in the return type.
3173  Out << Str;
3174  if (MD->isPure())
3175  Out << " [pure]";
3176 
3177  if (MD->isDeleted())
3178  Out << " [deleted]";
3179 
3180  ThunkInfo Thunk = VTableThunks.lookup(I);
3181  if (!Thunk.isEmpty())
3182  dumpMicrosoftThunkAdjustment(Thunk, Out, /*ContinueFirstLine=*/false);
3183 
3184  break;
3185  }
3186 
3188  const CXXDestructorDecl *DD = Component.getDestructorDecl();
3189 
3190  DD->printQualifiedName(Out);
3191  Out << "() [scalar deleting]";
3192 
3193  if (DD->isPure())
3194  Out << " [pure]";
3195 
3196  ThunkInfo Thunk = VTableThunks.lookup(I);
3197  if (!Thunk.isEmpty()) {
3198  assert(Thunk.Return.isEmpty() &&
3199  "No return adjustment needed for destructors!");
3200  dumpMicrosoftThunkAdjustment(Thunk, Out, /*ContinueFirstLine=*/false);
3201  }
3202 
3203  break;
3204  }
3205 
3206  default:
3207  DiagnosticsEngine &Diags = Context.getDiagnostics();
3208  unsigned DiagID = Diags.getCustomDiagID(
3210  "Unexpected vftable component type %0 for component number %1");
3211  Diags.Report(MostDerivedClass->getLocation(), DiagID)
3212  << I << Component.getKind();
3213  }
3214 
3215  Out << '\n';
3216  }
3217 
3218  Out << '\n';
3219 
3220  if (!Thunks.empty()) {
3221  // We store the method names in a map to get a stable order.
3222  std::map<std::string, const CXXMethodDecl *> MethodNamesAndDecls;
3223 
3224  for (const auto &I : Thunks) {
3225  const CXXMethodDecl *MD = I.first;
3228 
3229  MethodNamesAndDecls.insert(std::make_pair(MethodName, MD));
3230  }
3231 
3232  for (const auto &MethodNameAndDecl : MethodNamesAndDecls) {
3233  const std::string &MethodName = MethodNameAndDecl.first;
3234  const CXXMethodDecl *MD = MethodNameAndDecl.second;
3235 
3236  ThunkInfoVectorTy ThunksVector = Thunks[MD];
3237  llvm::stable_sort(ThunksVector, [](const ThunkInfo &LHS,
3238  const ThunkInfo &RHS) {
3239  // Keep different thunks with the same adjustments in the order they
3240  // were put into the vector.
3241  return std::tie(LHS.This, LHS.Return) < std::tie(RHS.This, RHS.Return);
3242  });
3243 
3244  Out << "Thunks for '" << MethodName << "' (" << ThunksVector.size();
3245  Out << (ThunksVector.size() == 1 ? " entry" : " entries") << ").\n";
3246 
3247  for (unsigned I = 0, E = ThunksVector.size(); I != E; ++I) {
3248  const ThunkInfo &Thunk = ThunksVector[I];
3249 
3250  Out << llvm::format("%4d | ", I);
3251  dumpMicrosoftThunkAdjustment(Thunk, Out, /*ContinueFirstLine=*/true);
3252  Out << '\n';
3253  }
3254 
3255  Out << '\n';
3256  }
3257  }
3258 
3259  Out.flush();
3260 }
3261 
3264  for (const CXXRecordDecl *Decl : B) {
3265  if (A.count(Decl))
3266  return true;
3267  }
3268  return false;
3269 }
3270 
3271 static bool rebucketPaths(VPtrInfoVector &Paths);
3272 
3273 /// Produces MSVC-compatible vbtable data. The symbols produced by this
3274 /// algorithm match those produced by MSVC 2012 and newer, which is different
3275 /// from MSVC 2010.
3276 ///
3277 /// MSVC 2012 appears to minimize the vbtable names using the following
3278 /// algorithm. First, walk the class hierarchy in the usual order, depth first,
3279 /// left to right, to find all of the subobjects which contain a vbptr field.
3280 /// Visiting each class node yields a list of inheritance paths to vbptrs. Each
3281 /// record with a vbptr creates an initially empty path.
3282 ///
3283 /// To combine paths from child nodes, the paths are compared to check for
3284 /// ambiguity. Paths are "ambiguous" if multiple paths have the same set of
3285 /// components in the same order. Each group of ambiguous paths is extended by
3286 /// appending the class of the base from which it came. If the current class
3287 /// node produced an ambiguous path, its path is extended with the current class.
3288 /// After extending paths, MSVC again checks for ambiguity, and extends any
3289 /// ambiguous path which wasn't already extended. Because each node yields an
3290 /// unambiguous set of paths, MSVC doesn't need to extend any path more than once
3291 /// to produce an unambiguous set of paths.
3292 ///
3293 /// TODO: Presumably vftables use the same algorithm.
3294 void MicrosoftVTableContext::computeVTablePaths(bool ForVBTables,
3295  const CXXRecordDecl *RD,
3296  VPtrInfoVector &Paths) {
3297  assert(Paths.empty());
3298  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3299 
3300  // Base case: this subobject has its own vptr.
3301  if (ForVBTables ? Layout.hasOwnVBPtr() : Layout.hasOwnVFPtr())
3302  Paths.push_back(std::make_unique<VPtrInfo>(RD));
3303 
3304  // Recursive case: get all the vbtables from our bases and remove anything
3305  // that shares a virtual base.
3307  for (const auto &B : RD->bases()) {
3308  const CXXRecordDecl *Base = B.getType()->getAsCXXRecordDecl();
3309  if (B.isVirtual() && VBasesSeen.count(Base))
3310  continue;
3311 
3312  if (!Base->isDynamicClass())
3313  continue;
3314 
3315  const VPtrInfoVector &BasePaths =
3316  ForVBTables ? enumerateVBTables(Base) : getVFPtrOffsets(Base);
3317 
3318  for (const std::unique_ptr<VPtrInfo> &BaseInfo : BasePaths) {
3319  // Don't include the path if it goes through a virtual base that we've
3320  // already included.
3321  if (setsIntersect(VBasesSeen, BaseInfo->ContainingVBases))
3322  continue;
3323 
3324  // Copy the path and adjust it as necessary.
3325  auto P = std::make_unique<VPtrInfo>(*BaseInfo);
3326 
3327  // We mangle Base into the path if the path would've been ambiguous and it
3328  // wasn't already extended with Base.
3329  if (P->MangledPath.empty() || P->MangledPath.back() != Base)
3330  P->NextBaseToMangle = Base;
3331 
3332  // Keep track of which vtable the derived class is going to extend with
3333  // new methods or bases. We append to either the vftable of our primary
3334  // base, or the first non-virtual base that has a vbtable.
3335  if (P->ObjectWithVPtr == Base &&
3336  Base == (ForVBTables ? Layout.getBaseSharingVBPtr()
3337  : Layout.getPrimaryBase()))
3338  P->ObjectWithVPtr = RD;
3339 
3340  // Keep track of the full adjustment from the MDC to this vtable. The
3341  // adjustment is captured by an optional vbase and a non-virtual offset.
3342  if (B.isVirtual())
3343  P->ContainingVBases.push_back(Base);
3344  else if (P->ContainingVBases.empty())
3345  P->NonVirtualOffset += Layout.getBaseClassOffset(Base);
3346 
3347  // Update the full offset in the MDC.
3348  P->FullOffsetInMDC = P->NonVirtualOffset;
3349  if (const CXXRecordDecl *VB = P->getVBaseWithVPtr())
3350  P->FullOffsetInMDC += Layout.getVBaseClassOffset(VB);
3351 
3352  Paths.push_back(std::move(P));
3353  }
3354 
3355  if (B.isVirtual())
3356  VBasesSeen.insert(Base);
3357 
3358  // After visiting any direct base, we've transitively visited all of its
3359  // morally virtual bases.
3360  for (const auto &VB : Base->vbases())
3361  VBasesSeen.insert(VB.getType()->getAsCXXRecordDecl());
3362  }
3363 
3364  // Sort the paths into buckets, and if any of them are ambiguous, extend all
3365  // paths in ambiguous buckets.
3366  bool Changed = true;
3367  while (Changed)
3368  Changed = rebucketPaths(Paths);
3369 }
3370 
3371 static bool extendPath(VPtrInfo &P) {
3372  if (P.NextBaseToMangle) {
3373  P.MangledPath.push_back(P.NextBaseToMangle);
3374  P.NextBaseToMangle = nullptr;// Prevent the path from being extended twice.
3375  return true;
3376  }
3377  return false;
3378 }
3379 
3380 static bool rebucketPaths(VPtrInfoVector &Paths) {
3381  // What we're essentially doing here is bucketing together ambiguous paths.
3382  // Any bucket with more than one path in it gets extended by NextBase, which
3383  // is usually the direct base of the inherited the vbptr. This code uses a
3384  // sorted vector to implement a multiset to form the buckets. Note that the
3385  // ordering is based on pointers, but it doesn't change our output order. The
3386  // current algorithm is designed to match MSVC 2012's names.
3388  llvm::make_pointee_range(Paths));
3389  llvm::sort(PathsSorted, [](const VPtrInfo &LHS, const VPtrInfo &RHS) {
3390  return LHS.MangledPath < RHS.MangledPath;
3391  });
3392  bool Changed = false;
3393  for (size_t I = 0, E = PathsSorted.size(); I != E;) {
3394  // Scan forward to find the end of the bucket.
3395  size_t BucketStart = I;
3396  do {
3397  ++I;
3398  } while (I != E &&
3399  PathsSorted[BucketStart].get().MangledPath ==
3400  PathsSorted[I].get().MangledPath);
3401 
3402  // If this bucket has multiple paths, extend them all.
3403  if (I - BucketStart > 1) {
3404  for (size_t II = BucketStart; II != I; ++II)
3405  Changed |= extendPath(PathsSorted[II]);
3406  assert(Changed && "no paths were extended to fix ambiguity");
3407  }
3408  }
3409  return Changed;
3410 }
3411 
3413 
3414 namespace {
3415 typedef llvm::SetVector<BaseSubobject, std::vector<BaseSubobject>,
3416  llvm::DenseSet<BaseSubobject>> FullPathTy;
3417 }
3418 
3419 // This recursive function finds all paths from a subobject centered at
3420 // (RD, Offset) to the subobject located at IntroducingObject.
3421 static void findPathsToSubobject(ASTContext &Context,
3422  const ASTRecordLayout &MostDerivedLayout,
3423  const CXXRecordDecl *RD, CharUnits Offset,
3424  BaseSubobject IntroducingObject,
3425  FullPathTy &FullPath,
3426  std::list<FullPathTy> &Paths) {
3427  if (BaseSubobject(RD, Offset) == IntroducingObject) {
3428  Paths.push_back(FullPath);
3429  return;
3430  }
3431 
3432  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3433 
3434  for (const CXXBaseSpecifier &BS : RD->bases()) {
3435  const CXXRecordDecl *Base = BS.getType()->getAsCXXRecordDecl();
3436  CharUnits NewOffset = BS.isVirtual()
3437  ? MostDerivedLayout.getVBaseClassOffset(Base)
3438  : Offset + Layout.getBaseClassOffset(Base);
3439  FullPath.insert(BaseSubobject(Base, NewOffset));
3440  findPathsToSubobject(Context, MostDerivedLayout, Base, NewOffset,
3441  IntroducingObject, FullPath, Paths);
3442  FullPath.pop_back();
3443  }
3444 }
3445 
3446 // Return the paths which are not subsets of other paths.
3447 static void removeRedundantPaths(std::list<FullPathTy> &FullPaths) {
3448  FullPaths.remove_if([&](const FullPathTy &SpecificPath) {
3449  for (const FullPathTy &OtherPath : FullPaths) {
3450  if (&SpecificPath == &OtherPath)
3451  continue;
3452  if (llvm::all_of(SpecificPath, [&](const BaseSubobject &BSO) {
3453  return OtherPath.contains(BSO);
3454  })) {
3455  return true;
3456  }
3457  }
3458  return false;
3459  });
3460 }
3461 
3463  const CXXRecordDecl *RD,
3464  const FullPathTy &FullPath) {
3465  const ASTRecordLayout &MostDerivedLayout =
3466  Context.getASTRecordLayout(RD);
3468  for (const BaseSubobject &BSO : FullPath) {
3469  const CXXRecordDecl *Base = BSO.getBase();
3470  // The first entry in the path is always the most derived record, skip it.
3471  if (Base == RD) {
3472  assert(Offset.getQuantity() == -1);
3473  Offset = CharUnits::Zero();
3474  continue;
3475  }
3476  assert(Offset.getQuantity() != -1);
3477  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3478  // While we know which base has to be traversed, we don't know if that base
3479  // was a virtual base.
3480  const CXXBaseSpecifier *BaseBS = std::find_if(
3481  RD->bases_begin(), RD->bases_end(), [&](const CXXBaseSpecifier &BS) {
3482  return BS.getType()->getAsCXXRecordDecl() == Base;
3483  });
3484  Offset = BaseBS->isVirtual() ? MostDerivedLayout.getVBaseClassOffset(Base)
3485  : Offset + Layout.getBaseClassOffset(Base);
3486  RD = Base;
3487  }
3488  return Offset;
3489 }
3490 
3491 // We want to select the path which introduces the most covariant overrides. If
3492 // two paths introduce overrides which the other path doesn't contain, issue a
3493 // diagnostic.
3494 static const FullPathTy *selectBestPath(ASTContext &Context,
3495  const CXXRecordDecl *RD,
3496  const VPtrInfo &Info,
3497  std::list<FullPathTy> &FullPaths) {
3498  // Handle some easy cases first.
3499  if (FullPaths.empty())
3500  return nullptr;
3501  if (FullPaths.size() == 1)
3502  return &FullPaths.front();
3503 
3504  const FullPathTy *BestPath = nullptr;
3505  typedef std::set<const CXXMethodDecl *> OverriderSetTy;
3506  OverriderSetTy LastOverrides;
3507  for (const FullPathTy &SpecificPath : FullPaths) {
3508  assert(!SpecificPath.empty());
3509  OverriderSetTy CurrentOverrides;
3510  const CXXRecordDecl *TopLevelRD = SpecificPath.begin()->getBase();
3511  // Find the distance from the start of the path to the subobject with the
3512  // VPtr.
3513  CharUnits BaseOffset =
3514  getOffsetOfFullPath(Context, TopLevelRD, SpecificPath);
3515  FinalOverriders Overriders(TopLevelRD, CharUnits::Zero(), TopLevelRD);
3516  for (const CXXMethodDecl *MD : Info.IntroducingObject->methods()) {
3518  continue;
3519  FinalOverriders::OverriderInfo OI =
3520  Overriders.getOverrider(MD->getCanonicalDecl(), BaseOffset);
3521  const CXXMethodDecl *OverridingMethod = OI.Method;
3522  // Only overriders which have a return adjustment introduce problematic
3523  // thunks.
3524  if (ComputeReturnAdjustmentBaseOffset(Context, OverridingMethod, MD)
3525  .isEmpty())
3526  continue;
3527  // It's possible that the overrider isn't in this path. If so, skip it
3528  // because this path didn't introduce it.
3529  const CXXRecordDecl *OverridingParent = OverridingMethod->getParent();
3530  if (llvm::none_of(SpecificPath, [&](const BaseSubobject &BSO) {
3531  return BSO.getBase() == OverridingParent;
3532  }))
3533  continue;
3534  CurrentOverrides.insert(OverridingMethod);
3535  }
3536  OverriderSetTy NewOverrides =
3537  llvm::set_difference(CurrentOverrides, LastOverrides);
3538  if (NewOverrides.empty())
3539  continue;
3540  OverriderSetTy MissingOverrides =
3541  llvm::set_difference(LastOverrides, CurrentOverrides);
3542  if (MissingOverrides.empty()) {
3543  // This path is a strict improvement over the last path, let's use it.
3544  BestPath = &SpecificPath;
3545  std::swap(CurrentOverrides, LastOverrides);
3546  } else {
3547  // This path introduces an overrider with a conflicting covariant thunk.
3548  DiagnosticsEngine &Diags = Context.getDiagnostics();
3549  const CXXMethodDecl *CovariantMD = *NewOverrides.begin();
3550  const CXXMethodDecl *ConflictMD = *MissingOverrides.begin();
3551  Diags.Report(RD->getLocation(), diag::err_vftable_ambiguous_component)
3552  << RD;
3553  Diags.Report(CovariantMD->getLocation(), diag::note_covariant_thunk)
3554  << CovariantMD;
3555  Diags.Report(ConflictMD->getLocation(), diag::note_covariant_thunk)
3556  << ConflictMD;
3557  }
3558  }
3559  // Go with the path that introduced the most covariant overrides. If there is
3560  // no such path, pick the first path.
3561  return BestPath ? BestPath : &FullPaths.front();
3562 }
3563 
3565  const CXXRecordDecl *RD,
3566  VPtrInfoVector &Paths) {
3567  const ASTRecordLayout &MostDerivedLayout = Context.getASTRecordLayout(RD);
3568  FullPathTy FullPath;
3569  std::list<FullPathTy> FullPaths;
3570  for (const std::unique_ptr<VPtrInfo>& Info : Paths) {
3572  Context, MostDerivedLayout, RD, CharUnits::Zero(),
3573  BaseSubobject(Info->IntroducingObject, Info->FullOffsetInMDC), FullPath,
3574  FullPaths);
3575  FullPath.clear();
3576  removeRedundantPaths(FullPaths);
3577  Info->PathToIntroducingObject.clear();
3578  if (const FullPathTy *BestPath =
3579  selectBestPath(Context, RD, *Info, FullPaths))
3580  for (const BaseSubobject &BSO : *BestPath)
3581  Info->PathToIntroducingObject.push_back(BSO.getBase());
3582  FullPaths.clear();
3583  }
3584 }
3585 
3586 static bool vfptrIsEarlierInMDC(const ASTRecordLayout &Layout,
3587  const MethodVFTableLocation &LHS,
3588  const MethodVFTableLocation &RHS) {
3589  CharUnits L = LHS.VFPtrOffset;
3590  CharUnits R = RHS.VFPtrOffset;
3591  if (LHS.VBase)
3592  L += Layout.getVBaseClassOffset(LHS.VBase);
3593  if (RHS.VBase)
3594  R += Layout.getVBaseClassOffset(RHS.VBase);
3595  return L < R;
3596 }
3597 
3598 void MicrosoftVTableContext::computeVTableRelatedInformation(
3599  const CXXRecordDecl *RD) {
3600  assert(RD->isDynamicClass());
3601 
3602  // Check if we've computed this information before.
3603  if (VFPtrLocations.count(RD))
3604  return;
3605 
3606  const VTableLayout::AddressPointsMapTy EmptyAddressPointsMap;
3607 
3608  {
3609  auto VFPtrs = std::make_unique<VPtrInfoVector>();
3610  computeVTablePaths(/*ForVBTables=*/false, RD, *VFPtrs);
3611  computeFullPathsForVFTables(Context, RD, *VFPtrs);
3612  VFPtrLocations[RD] = std::move(VFPtrs);
3613  }
3614 
3615  MethodVFTableLocationsTy NewMethodLocations;
3616  for (const std::unique_ptr<VPtrInfo> &VFPtr : *VFPtrLocations[RD]) {
3617  VFTableBuilder Builder(*this, RD, *VFPtr);
3618 
3619  VFTableIdTy id(RD, VFPtr->FullOffsetInMDC);
3620  assert(VFTableLayouts.count(id) == 0);
3622  Builder.vtable_thunks_begin(), Builder.vtable_thunks_end());
3623  VFTableLayouts[id] = std::make_unique<VTableLayout>(
3624  ArrayRef<size_t>{0}, Builder.vtable_components(), VTableThunks,
3625  EmptyAddressPointsMap);
3626  Thunks.insert(Builder.thunks_begin(), Builder.thunks_end());
3627 
3628  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3629  for (const auto &Loc : Builder.vtable_locations()) {
3630  auto Insert = NewMethodLocations.insert(Loc);
3631  if (!Insert.second) {
3632  const MethodVFTableLocation &NewLoc = Loc.second;
3633  MethodVFTableLocation &OldLoc = Insert.first->second;
3634  if (vfptrIsEarlierInMDC(Layout, NewLoc, OldLoc))
3635  OldLoc = NewLoc;
3636  }
3637  }
3638  }
3639 
3640  MethodVFTableLocations.insert(NewMethodLocations.begin(),
3641  NewMethodLocations.end());
3642  if (Context.getLangOpts().DumpVTableLayouts)
3643  dumpMethodLocations(RD, NewMethodLocations, llvm::outs());
3644 }
3645 
3646 void MicrosoftVTableContext::dumpMethodLocations(
3647  const CXXRecordDecl *RD, const MethodVFTableLocationsTy &NewMethods,
3648  raw_ostream &Out) {
3649  // Compute the vtable indices for all the member functions.
3650  // Store them in a map keyed by the location so we'll get a sorted table.
3651  std::map<MethodVFTableLocation, std::string> IndicesMap;
3652  bool HasNonzeroOffset = false;
3653 
3654  for (const auto &I : NewMethods) {
3655  const CXXMethodDecl *MD = cast<const CXXMethodDecl>(I.first.getDecl());
3656  assert(hasVtableSlot(MD));
3657 
3660 
3661  if (isa<CXXDestructorDecl>(MD)) {
3662  IndicesMap[I.second] = MethodName + " [scalar deleting]";
3663  } else {
3664  IndicesMap[I.second] = MethodName;
3665  }
3666 
3667  if (!I.second.VFPtrOffset.isZero() || I.second.VBTableIndex != 0)
3668  HasNonzeroOffset = true;
3669  }
3670 
3671  // Print the vtable indices for all the member functions.
3672  if (!IndicesMap.empty()) {
3673  Out << "VFTable indices for ";
3674  Out << "'";
3675  RD->printQualifiedName(Out);
3676  Out << "' (" << IndicesMap.size()
3677  << (IndicesMap.size() == 1 ? " entry" : " entries") << ").\n";
3678 
3679  CharUnits LastVFPtrOffset = CharUnits::fromQuantity(-1);
3680  uint64_t LastVBIndex = 0;
3681  for (const auto &I : IndicesMap) {
3682  CharUnits VFPtrOffset = I.first.VFPtrOffset;
3683  uint64_t VBIndex = I.first.VBTableIndex;
3684  if (HasNonzeroOffset &&
3685  (VFPtrOffset != LastVFPtrOffset || VBIndex != LastVBIndex)) {
3686  assert(VBIndex > LastVBIndex || VFPtrOffset > LastVFPtrOffset);
3687  Out << " -- accessible via ";
3688  if (VBIndex)
3689  Out << "vbtable index " << VBIndex << ", ";
3690  Out << "vfptr at offset " << VFPtrOffset.getQuantity() << " --\n";
3691  LastVFPtrOffset = VFPtrOffset;
3692  LastVBIndex = VBIndex;
3693  }
3694 
3695  uint64_t VTableIndex = I.first.Index;
3696  const std::string &MethodName = I.second;
3697  Out << llvm::format("%4" PRIu64 " | ", VTableIndex) << MethodName << '\n';
3698  }
3699  Out << '\n';
3700  }
3701 
3702  Out.flush();
3703 }
3704 
3705 const VirtualBaseInfo &MicrosoftVTableContext::computeVBTableRelatedInformation(
3706  const CXXRecordDecl *RD) {
3707  VirtualBaseInfo *VBI;
3708 
3709  {
3710  // Get or create a VBI for RD. Don't hold a reference to the DenseMap cell,
3711  // as it may be modified and rehashed under us.
3712  std::unique_ptr<VirtualBaseInfo> &Entry = VBaseInfo[RD];
3713  if (Entry)
3714  return *Entry;
3715  Entry = std::make_unique<VirtualBaseInfo>();
3716  VBI = Entry.get();
3717  }
3718 
3719  computeVTablePaths(/*ForVBTables=*/true, RD, VBI->VBPtrPaths);
3720 
3721  // First, see if the Derived class shared the vbptr with a non-virtual base.
3722  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3723  if (const CXXRecordDecl *VBPtrBase = Layout.getBaseSharingVBPtr()) {
3724  // If the Derived class shares the vbptr with a non-virtual base, the shared
3725  // virtual bases come first so that the layout is the same.
3726  const VirtualBaseInfo &BaseInfo =
3727  computeVBTableRelatedInformation(VBPtrBase);
3728  VBI->VBTableIndices.insert(BaseInfo.VBTableIndices.begin(),
3729  BaseInfo.VBTableIndices.end());
3730  }
3731 
3732  // New vbases are added to the end of the vbtable.
3733  // Skip the self entry and vbases visited in the non-virtual base, if any.
3734  unsigned VBTableIndex = 1 + VBI->VBTableIndices.size();
3735  for (const auto &VB : RD->vbases()) {
3736  const CXXRecordDecl *CurVBase = VB.getType()->getAsCXXRecordDecl();
3737  if (!VBI->VBTableIndices.count(CurVBase))
3738  VBI->VBTableIndices[CurVBase] = VBTableIndex++;
3739  }
3740 
3741  return *VBI;
3742 }
3743 
3745  const CXXRecordDecl *VBase) {
3746  const VirtualBaseInfo &VBInfo = computeVBTableRelatedInformation(Derived);
3747  assert(VBInfo.VBTableIndices.count(VBase));
3748  return VBInfo.VBTableIndices.find(VBase)->second;
3749 }
3750 
3751 const VPtrInfoVector &
3753  return computeVBTableRelatedInformation(RD).VBPtrPaths;
3754 }
3755 
3756 const VPtrInfoVector &
3758  computeVTableRelatedInformation(RD);
3759 
3760  assert(VFPtrLocations.count(RD) && "Couldn't find vfptr locations");
3761  return *VFPtrLocations[RD];
3762 }
3763 
3764 const VTableLayout &
3766  CharUnits VFPtrOffset) {
3767  computeVTableRelatedInformation(RD);
3768 
3769  VFTableIdTy id(RD, VFPtrOffset);
3770  assert(VFTableLayouts.count(id) && "Couldn't find a VFTable at this offset");
3771  return *VFTableLayouts[id];
3772 }
3773 
3776  assert(hasVtableSlot(cast<CXXMethodDecl>(GD.getDecl())) &&
3777  "Only use this method for virtual methods or dtors");
3778  if (isa<CXXDestructorDecl>(GD.getDecl()))
3779  assert(GD.getDtorType() == Dtor_Deleting);
3780 
3781  GD = GD.getCanonicalDecl();
3782 
3783  MethodVFTableLocationsTy::iterator I = MethodVFTableLocations.find(GD);
3784  if (I != MethodVFTableLocations.end())
3785  return I->second;
3786 
3787  const CXXRecordDecl *RD = cast<CXXMethodDecl>(GD.getDecl())->getParent();
3788 
3789  computeVTableRelatedInformation(RD);
3790 
3791  I = MethodVFTableLocations.find(GD);
3792  assert(I != MethodVFTableLocations.end() && "Did not find index!");
3793  return I->second;
3794 }
clang::ASTContext::getTypeSizeInChars
CharUnits getTypeSizeInChars(QualType T) const
Return the size of the specified (complete) type T, in characters.
Definition: ASTContext.cpp:2471
clang::GlobalDecl::getDtorType
CXXDtorType getDtorType() const
Definition: GlobalDecl.h:110
clang::ReturnAdjustment::VirtualAdjustment::VBPtrOffset
uint32_t VBPtrOffset
The offset (in bytes) of the vbptr, relative to the beginning of the derived class.
Definition: Thunk.h:45
clang::VTableComponent::MakeRTTI
static VTableComponent MakeRTTI(const CXXRecordDecl *RD)
Definition: VTableBuilder.h:67
clang::VTableLayout::VTableThunkTy
std::pair< uint64_t, ThunkInfo > VTableThunkTy
Definition: VTableBuilder.h:235
clang::Decl::getASTContext
ASTContext & getASTContext() const LLVM_READONLY
Definition: DeclBase.cpp:414
clang::CXXBaseSpecifier::getType
QualType getType() const
Retrieves the type of the base class.
Definition: DeclCXX.h:245
clang::VTableComponent::CK_VCallOffset
@ CK_VCallOffset
Definition: VTableBuilder.h:33
removeRedundantPaths
static void removeRedundantPaths(std::list< FullPathTy > &FullPaths)
Definition: VTableBuilder.cpp:3447
clang::DeclContext::decls
decl_range decls() const
decls_begin/decls_end - Iterate over the declarations stored in this context.
Definition: DeclBase.h:2137
clang::VTableComponent::MakeUnusedFunction
static VTableComponent MakeUnusedFunction(const CXXMethodDecl *MD)
Definition: VTableBuilder.h:89
LT
ASTImporterLookupTable & LT
Definition: ASTImporterLookupTable.cpp:24
clang::VPtrInfo::IntroducingObject
const CXXRecordDecl * IntroducingObject
This is the class that introduced the vptr by declaring new virtual methods or virtual bases.
Definition: VTableBuilder.h:459
clang::CXXFinalOverriderMap
A mapping from each virtual member function to its set of final overriders.
Definition: CXXInheritance.h:357
llvm::OwningArrayRef< size_t >
clang::FunctionDecl::getReturnType
QualType getReturnType() const
Definition: Decl.h:2564
clang::ReturnAdjustment::VirtualAdjustment::Microsoft
struct clang::ReturnAdjustment::VirtualAdjustment::@179 Microsoft
PrintBasePath
static void PrintBasePath(const VPtrInfo::BasePath &Path, raw_ostream &Out)
Definition: VTableBuilder.cpp:3100
clang::ItaniumVTableContext::ItaniumVTableContext
ItaniumVTableContext(ASTContext &Context, VTableComponentLayout ComponentLayout=Pointer)
Definition: VTableBuilder.cpp:2264
string
string(SUBSTRING ${CMAKE_CURRENT_BINARY_DIR} 0 ${PATH_LIB_START} PATH_HEAD) string(SUBSTRING $
Definition: CMakeLists.txt:22
Ret
static bool Ret(InterpState &S, CodePtr &PC, APValue &Result)
Definition: Interp.cpp:34
clang::VTableComponent::getOffsetToTop
CharUnits getOffsetToTop() const
Definition: VTableBuilder.h:113
rebucketPaths
static bool rebucketPaths(VPtrInfoVector &Paths)
Definition: VTableBuilder.cpp:3380
clang::VTableComponent::getRTTIDecl
const CXXRecordDecl * getRTTIDecl() const
Definition: VTableBuilder.h:119
clang::FunctionDecl::isDeleted
bool isDeleted() const
Whether this function has been deleted.
Definition: Decl.h:2361
llvm::SmallVector
Definition: LLVM.h:38
clang::TargetCXXABI::isMicrosoft
bool isMicrosoft() const
Is this ABI an MSVC-compatible ABI?
Definition: TargetCXXABI.h:138
clang::VTableComponent
Represents a single component in a vtable.
Definition: VTableBuilder.h:30
TargetInfo.h
CXXInheritance.h
clang::VTableComponent::getFunctionDecl
const CXXMethodDecl * getFunctionDecl() const
Definition: VTableBuilder.h:124
clang::QualType
A (possibly-)qualified type.
Definition: Type.h:731
clang::ASTRecordLayout::getBaseClassOffset
CharUnits getBaseClassOffset(const CXXRecordDecl *Base) const
getBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:249
clang::VTableComponent::MakeFunction
static VTableComponent MakeFunction(const CXXMethodDecl *MD)
Definition: VTableBuilder.h:71
clang::QualType::getCanonicalType
QualType getCanonicalType() const
Definition: Type.h:6598
clang::MicrosoftVTableContext::enumerateVBTables
const VPtrInfoVector & enumerateVBTables(const CXXRecordDecl *RD)
Definition: VTableBuilder.cpp:3752
clang::DiagnosticsEngine
Concrete class used by the front-end to report problems and issues.
Definition: Diagnostic.h:192
clang::TargetInfo::getCXXABI
TargetCXXABI getCXXABI() const
Get the C++ ABI currently in use.
Definition: TargetInfo.h:1245
clang::CXXMethodDecl::getCanonicalDecl
CXXMethodDecl * getCanonicalDecl() override
Retrieves the "canonical" declaration of the given declaration.
Definition: DeclCXX.h:2066
clang::VTableComponent::MakeDeletingDtor
static VTableComponent MakeDeletingDtor(const CXXDestructorDecl *DD)
Definition: VTableBuilder.h:84
clang::VTableComponent::getVBaseOffset
CharUnits getVBaseOffset() const
Definition: VTableBuilder.h:107
clang::ComparisonCategoryType::First
@ First
llvm::SmallPtrSet
Definition: ASTContext.h:82
clang::VTableComponent::CK_RTTI
@ CK_RTTI
Definition: VTableBuilder.h:36
clang::ASTRecordLayout::getPrimaryBase
const CXXRecordDecl * getPrimaryBase() const
getPrimaryBase - Get the primary base for this record.
Definition: RecordLayout.h:234
clang::ItaniumVTableContext::getMethodVTableIndex
uint64_t getMethodVTableIndex(GlobalDecl GD)
Locate a virtual function in the vtable.
Definition: VTableBuilder.cpp:2270
clang::diag::Group
Group
Definition: DiagnosticCategories.h:23
clang::ReturnAdjustment::Virtual
union clang::ReturnAdjustment::VirtualAdjustment Virtual
isDirectVBase
static bool isDirectVBase(const CXXRecordDecl *Base, const CXXRecordDecl *RD)
Definition: VTableBuilder.cpp:2933
clang::FunctionType
FunctionType - C99 6.7.5.3 - Function Declarators.
Definition: Type.h:3618
clang::VTableComponent::MakeVBaseOffset
static VTableComponent MakeVBaseOffset(CharUnits Offset)
Definition: VTableBuilder.h:59
clang::DeclarationName
The name of a declaration.
Definition: DeclarationName.h:144
clang::CXXRecordDecl::bases_end
base_class_iterator bases_end()
Definition: DeclCXX.h:605
CreateVTableLayout
static std::unique_ptr< VTableLayout > CreateVTableLayout(const ItaniumVTableBuilder &Builder)
Definition: VTableBuilder.cpp:2314
clang::ReturnAdjustment::VirtualAdjustment::Itanium
struct clang::ReturnAdjustment::VirtualAdjustment::@178 Itanium
clang::Dtor_Complete
@ Dtor_Complete
Complete object dtor.
Definition: ABI.h:35
clang::UniqueVirtualMethod::Method
CXXMethodDecl * Method
The overriding virtual method.
Definition: CXXInheritance.h:232
clang::FunctionDecl::isConsteval
bool isConsteval() const
Definition: Decl.h:2318
computeFullPathsForVFTables
static void computeFullPathsForVFTables(ASTContext &Context, const CXXRecordDecl *RD, VPtrInfoVector &Paths)
Definition: VTableBuilder.cpp:3564
clang::OverridingMethods
The set of methods that override a given virtual method in each subobject where it occurs.
Definition: CXXInheritance.h:269
getOffsetOfFullPath
static CharUnits getOffsetOfFullPath(ASTContext &Context, const CXXRecordDecl *RD, const FullPathTy &FullPath)
Definition: VTableBuilder.cpp:3462
clang::ThisAdjustment::VirtualAdjustment::VtordispOffset
int32_t VtordispOffset
The offset of the vtordisp (in bytes), relative to the ECX.
Definition: Thunk.h:108
clang::VTableComponent::CK_UnusedFunctionPointer
@ CK_UnusedFunctionPointer
An entry that is never used.
Definition: VTableBuilder.h:50
clang::MicrosoftVTableContext::~MicrosoftVTableContext
~MicrosoftVTableContext() override
Definition: VTableBuilder.cpp:3412
Offset
unsigned Offset
Definition: Format.cpp:2574
clang::GlobalDecl
GlobalDecl - represents a global declaration.
Definition: GlobalDecl.h:56
clang::ItaniumVTableContext::VTableComponentLayout
VTableComponentLayout
Definition: VTableBuilder.h:390
uint64_t
unsigned long uint64_t
Definition: hlsl_basic_types.h:24
dumpMicrosoftThunkAdjustment
static void dumpMicrosoftThunkAdjustment(const ThunkInfo &TI, raw_ostream &Out, bool ContinueFirstLine)
Definition: VTableBuilder.cpp:3108
clang::VPtrInfo::NonVirtualOffset
CharUnits NonVirtualOffset
IntroducingObject is at this offset from its containing complete object or virtual base.
Definition: VTableBuilder.h:463
clang::VTableLayout::~VTableLayout
~VTableLayout()
Definition: VTableBuilder.cpp:2258
vfptrIsEarlierInMDC
static bool vfptrIsEarlierInMDC(const ASTRecordLayout &Layout, const MethodVFTableLocation &LHS, const MethodVFTableLocation &RHS)
Definition: VTableBuilder.cpp:3586
clang::CXXRecordDecl::vbases_begin
base_class_iterator vbases_begin()
Definition: DeclCXX.h:620
clang::VTableLayout::AddressPointLocation
Definition: VTableBuilder.h:236
clang::VirtualBaseInfo::VBTableIndices
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...
Definition: VTableBuilder.h:503
selectBestPath
static const FullPathTy * selectBestPath(ASTContext &Context, const CXXRecordDecl *RD, const VPtrInfo &Info, std::list< FullPathTy > &FullPaths)
Definition: VTableBuilder.cpp:3494
clang::CXXMethodDecl::overridden_methods
overridden_method_range overridden_methods() const
Definition: DeclCXX.cpp:2448
clang::GlobalDecl::getCanonicalDecl
GlobalDecl getCanonicalDecl() const
Definition: GlobalDecl.h:94
GroupNewVirtualOverloads
static void GroupNewVirtualOverloads(const CXXRecordDecl *RD, SmallVector< const CXXMethodDecl *, 10 > &VirtualMethods)
Definition: VTableBuilder.cpp:2901
clang::CXXRecordDecl::methods
method_range methods() const
Definition: DeclCXX.h:638
clang::VTableComponent::getKind
Kind getKind() const
Get the kind of this vtable component.
Definition: VTableBuilder.h:97
clang::BaseSubobject
Definition: BaseSubobject.h:30
clang::CharUnits::fromQuantity
static CharUnits fromQuantity(QuantityType Quantity)
fromQuantity - Construct a CharUnits quantity from a raw integer type.
Definition: CharUnits.h:63
clang::MethodVFTableLocation::VBase
const CXXRecordDecl * VBase
If nonnull, holds the last vbase which contains the vfptr that the method definition is adjusted to.
Definition: VTableBuilder.h:516
clang::ASTContext
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:208
clang::VTableComponent::CK_FunctionPointer
@ CK_FunctionPointer
Definition: VTableBuilder.h:37
clang::dataflow::LatticeJoinEffect::Changed
@ Changed
clang::MicrosoftVTableContext::getVFPtrOffsets
const VPtrInfoVector & getVFPtrOffsets(const CXXRecordDecl *RD)
Definition: VTableBuilder.cpp:3757
clang::DiagnosticsEngine::Error
@ Error
Definition: Diagnostic.h:200
clang::VTableComponent::CK_DeletingDtorPointer
@ CK_DeletingDtorPointer
A pointer to the deleting destructor.
Definition: VTableBuilder.h:43
clang::MicrosoftVTableContext::getVFTableLayout
const VTableLayout & getVFTableLayout(const CXXRecordDecl *RD, CharUnits VFPtrOffset)
Definition: VTableBuilder.cpp:3765
extendPath
static bool extendPath(VPtrInfo &P)
Definition: VTableBuilder.cpp:3371
clang::VPtrInfo::getVBaseWithVPtr
const CXXRecordDecl * getVBaseWithVPtr() const
The vptr is stored inside the non-virtual component of this virtual base.
Definition: VTableBuilder.h:490
clang::ThisAdjustment::VirtualAdjustment::Itanium
struct clang::ThisAdjustment::VirtualAdjustment::@180 Itanium
clang::CXXDestructorDecl
Represents a C++ destructor within a class.
Definition: DeclCXX.h:2701
clang::CXXBaseSpecifier::isVirtual
bool isVirtual() const
Determines whether the base class is a virtual base class (or not).
Definition: DeclCXX.h:199
clang::VTableComponent::CK_VBaseOffset
@ CK_VBaseOffset
Definition: VTableBuilder.h:34
clang::CXXBasePathElement
Represents an element in a path from a derived class to a base class.
Definition: CXXInheritance.h:44
ASTContext.h
clang::ASTRecordLayout::getVBPtrOffset
CharUnits getVBPtrOffset() const
getVBPtrOffset - Get the offset for virtual base table pointer.
Definition: RecordLayout.h:324
clang::FunctionProtoType::getParamTypes
ArrayRef< QualType > getParamTypes() const
Definition: Type.h:4174
clang::VTableComponent::CK_CompleteDtorPointer
@ CK_CompleteDtorPointer
A pointer to the complete destructor.
Definition: VTableBuilder.h:40
clang::ItaniumVTableContext::getVirtualBaseOffsetOffset
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...
Definition: VTableBuilder.cpp:2286
clang::ReturnAdjustment
A return adjustment.
Definition: Thunk.h:26
clang::ASTContext::getCanonicalType
CanQualType getCanonicalType(QualType T) const
Return the canonical (structural) type corresponding to the specified potentially non-canonical type ...
Definition: ASTContext.h:2508
clang::CXXRecordDecl::isDerivedFrom
bool isDerivedFrom(const CXXRecordDecl *Base) const
Determine whether this class is derived from the class Base.
Definition: CXXInheritance.cpp:68
llvm::DenseSet
Definition: Sema.h:77
clang::Type::getAsCXXRecordDecl
CXXRecordDecl * getAsCXXRecordDecl() const
Retrieves the CXXRecordDecl that this type refers to, either because the type is a RecordType or beca...
Definition: Type.cpp:1759
clang::UniqueVirtualMethod
Uniquely identifies a virtual method within a class hierarchy by the method itself and a class subobj...
Definition: CXXInheritance.h:230
clang::CXXRecordDecl::bases
base_class_range bases()
Definition: DeclCXX.h:596
clang::VPtrInfo
Holds information about the inheritance path to a virtual base or function table pointer.
Definition: VTableBuilder.h:446
clang::CharUnits::Zero
static CharUnits Zero()
Zero - Construct a CharUnits quantity of zero.
Definition: CharUnits.h:53
clang::CanQual< Type >
Base
clang::ThunkInfo::This
ThisAdjustment This
The this pointer adjustment.
Definition: Thunk.h:158
ASTDiagnostic.h
getKind
static Decl::Kind getKind(const Decl *D)
Definition: DeclBase.cpp:1008
clang::CXXRecordDecl::vbases
base_class_range vbases()
Definition: DeclCXX.h:613
clang::Decl::isImplicit
bool isImplicit() const
isImplicit - Indicates whether the declaration was implicitly generated by the implementation.
Definition: DeclBase.h:558
clang::ASTRecordLayout::isPrimaryBaseVirtual
bool isPrimaryBaseVirtual() const
isPrimaryBaseVirtual - Get whether the primary base for this record is virtual or not.
Definition: RecordLayout.h:242
clang::ASTRecordLayout::getVBaseClassOffset
CharUnits getVBaseClassOffset(const CXXRecordDecl *VBase) const
getVBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:259
clang::VTableLayout::AddressPointsMapTy
llvm::DenseMap< BaseSubobject, AddressPointLocation > AddressPointsMapTy
Definition: VTableBuilder.h:240
clang::VirtualBaseInfo::VBPtrPaths
VPtrInfoVector VBPtrPaths
Information on all virtual base tables used when this record is the most derived class.
Definition: VTableBuilder.h:507
clang::Type::castAs
const T * castAs() const
Member-template castAs<specific type>.
Definition: Type.h:7369
clang::PredefinedExpr::ComputeName
static std::string ComputeName(IdentKind IK, const Decl *CurrentDecl)
Definition: Expr.cpp:726
clang::ASTRecordLayout
ASTRecordLayout - This class contains layout information for one RecordDecl, which is a struct/union/...
Definition: RecordLayout.h:38
setsIntersect
static bool setsIntersect(const llvm::SmallPtrSet< const CXXRecordDecl *, 4 > &A, ArrayRef< const CXXRecordDecl * > B)
Definition: VTableBuilder.cpp:3262
clang::ThisAdjustment::VirtualAdjustment::VBPtrOffset
int32_t VBPtrOffset
The offset of the vbptr of the derived class (in bytes), relative to the ECX after vtordisp adjustmen...
Definition: Thunk.h:112
clang::ThunkInfo::Return
ReturnAdjustment Return
The return adjustment.
Definition: Thunk.h:161
clang::ThisAdjustment::NonVirtual
int64_t NonVirtual
The non-virtual adjustment from the derived object to its nearest virtual base.
Definition: Thunk.h:94
clang::CXXRecordDecl
Represents a C++ struct/union/class.
Definition: DeclCXX.h:254
P
StringRef P
Definition: ASTMatchersInternal.cpp:563
clang::ReturnAdjustment::VirtualAdjustment::VBIndex
uint32_t VBIndex
Index of the virtual base in the vbtable.
Definition: Thunk.h:48
VTableBuilder.h
clang::CXXMethodDecl::size_overridden_methods
unsigned size_overridden_methods() const
Definition: DeclCXX.cpp:2442
clang::ReturnAdjustment::isEmpty
bool isEmpty() const
Definition: Thunk.h:69
false
#define false
Definition: stdbool.h:22
clang::ASTRecordLayout::getVBaseOffsetsMap
const VBaseOffsetsMapTy & getVBaseOffsetsMap() const
Definition: RecordLayout.h:334
clang::ThisAdjustment::Virtual
union clang::ThisAdjustment::VirtualAdjustment Virtual
clang::CXXRecordDecl::getNumVBases
unsigned getNumVBases() const
Retrieves the number of virtual base classes of this class.
Definition: DeclCXX.h:611
clang::VTableComponent::getDestructorDecl
const CXXDestructorDecl * getDestructorDecl() const
Definition: VTableBuilder.h:131
clang::ASTContext::IntTy
CanQualType IntTy
Definition: ASTContext.h:1105
clang::CharUnits::isZero
bool isZero() const
isZero - Test whether the quantity equals zero.
Definition: CharUnits.h:116
clang::ASTRecordLayout::hasOwnVFPtr
bool hasOwnVFPtr() const
hasOwnVFPtr - Does this class provide its own virtual-function table pointer, rather than inheriting ...
Definition: RecordLayout.h:280
clang::FunctionProtoType
Represents a prototype with parameter type info, e.g.
Definition: Type.h:3956
dump
static void dump(llvm::raw_ostream &OS, StringRef FunctionName, ArrayRef< CounterExpression > Expressions, ArrayRef< CounterMappingRegion > Regions)
Definition: CoverageMappingGen.cpp:1533
clang::DeclContext::getParent
DeclContext * getParent()
getParent - Returns the containing DeclContext.
Definition: DeclBase.h:1882
clang::ASTRecordLayout::VBaseOffsetsMapTy
llvm::DenseMap< const CXXRecordDecl *, VBaseInfo > VBaseOffsetsMapTy
Definition: RecordLayout.h:59
Specifier
const NestedNameSpecifier * Specifier
Definition: USRLocFinder.cpp:173
clang::ItaniumVTableContext
Definition: VTableBuilder.h:363
llvm::ArrayRef
Definition: LLVM.h:34
clang::VTableComponent::CK_OffsetToTop
@ CK_OffsetToTop
Definition: VTableBuilder.h:35
clang::Decl
Decl - This represents one declaration (or definition), e.g.
Definition: DeclBase.h:83
clang::FunctionDecl::isPure
bool isPure() const
Whether this virtual function is pure, i.e.
Definition: Decl.h:2206
MakeAddressPointIndices
static VTableLayout::AddressPointsIndexMapTy MakeAddressPointIndices(const VTableLayout::AddressPointsMapTy &addressPoints, unsigned numVTables)
Definition: VTableBuilder.cpp:2212
clang::ThunkInfo
The this pointer adjustment as well as an optional return adjustment for a thunk.
Definition: Thunk.h:156
clang::ASTRecordLayout::hasOwnVBPtr
bool hasOwnVBPtr() const
hasOwnVBPtr - Does this class provide its own virtual-base table pointer, rather than inheriting one ...
Definition: RecordLayout.h:300
clang::ASTRecordLayout::getBaseSharingVBPtr
const CXXRecordDecl * getBaseSharingVBPtr() const
Definition: RecordLayout.h:329
clang::ThisAdjustment::VirtualAdjustment::Microsoft
struct clang::ThisAdjustment::VirtualAdjustment::@181 Microsoft
clang::MicrosoftVTableContext
Definition: VTableBuilder.h:544
clang::NamedDecl::getQualifiedNameAsString
std::string getQualifiedNameAsString() const
Definition: Decl.cpp:1605
clang::VPtrInfo::FullOffsetInMDC
CharUnits FullOffsetInMDC
Static offset from the top of the most derived class to this vfptr, including any virtual base offset...
Definition: VTableBuilder.h:487
clang::ASTContext::getTargetInfo
const TargetInfo & getTargetInfo() const
Definition: ASTContext.h:768
clang::MicrosoftVTableContext::getVBTableIndex
unsigned getVBTableIndex(const CXXRecordDecl *Derived, const CXXRecordDecl *VBase)
Returns the index of VBase in the vbtable of Derived.
Definition: VTableBuilder.cpp:3744
clang::VTableLayout::VTableLayout
VTableLayout(ArrayRef< size_t > VTableIndices, ArrayRef< VTableComponent > VTableComponents, ArrayRef< VTableThunkTy > VTableThunks, const AddressPointsMapTy &AddressPoints)
Definition: VTableBuilder.cpp:2238
clang::ThisAdjustment::isEmpty
bool isEmpty() const
Definition: Thunk.h:136
clang::FunctionProtoType::getMethodQuals
Qualifiers getMethodQuals() const
Definition: Type.h:4307
clang::ThisAdjustment::VirtualAdjustment::VCallOffsetOffset
int64_t VCallOffsetOffset
The offset (in bytes), relative to the address point, of the virtual call offset.
Definition: Thunk.h:103
clang::VTableComponent::MakeOffsetToTop
static VTableComponent MakeOffsetToTop(CharUnits Offset)
Definition: VTableBuilder.h:63
int64_t
long int64_t
Definition: hlsl_basic_types.h:25
clang::VTableComponent::getVCallOffset
CharUnits getVCallOffset() const
Definition: VTableBuilder.h:101
clang::ThisAdjustment::VirtualAdjustment::isEmpty
bool isEmpty() const
Definition: Thunk.h:124
clang::ThunkInfo::Method
const CXXMethodDecl * Method
Holds a pointer to the overridden method this thunk is for, if needed by the ABI to distinguish diffe...
Definition: Thunk.h:168
clang::VPtrInfo::PathToIntroducingObject
BasePath PathToIntroducingObject
This holds the base classes path from the complete type to the first base with the given vfptr offset...
Definition: VTableBuilder.h:483
clang::PointerType
PointerType - C99 6.7.5.1 - Pointer Declarators.
Definition: Type.h:2712
clang::VTableComponent::MakeVCallOffset
static VTableComponent MakeVCallOffset(CharUnits Offset)
Definition: VTableBuilder.h:55
clang::VPtrInfo::MangledPath
BasePath MangledPath
The bases from the inheritance path that got used to mangle the vbtable name.
Definition: VTableBuilder.h:469
clang::ItaniumVTableContext::createConstructionVTableLayout
std::unique_ptr< VTableLayout > createConstructionVTableLayout(const CXXRecordDecl *MostDerivedClass, CharUnits MostDerivedClassOffset, bool MostDerivedClassIsVirtual, const CXXRecordDecl *LayoutClass)
Definition: VTableBuilder.cpp:2362
clang::ThunkInfo::isEmpty
bool isEmpty() const
Definition: Thunk.h:181
clang::CanQual::getUnqualifiedType
CanQual< T > getUnqualifiedType() const
Retrieve the unqualified form of this type.
Definition: CanonicalType.h:620
clang::VTableLayout
Definition: VTableBuilder.h:233
clang::DiagnosticsEngine::getCustomDiagID
unsigned getCustomDiagID(Level L, const char(&FormatString)[N])
Return an ID for a diagnostic with the specified format string and level.
Definition: Diagnostic.h:868
clang::CXXBasePath
Represents a path from a specific derived class (which is not represented as part of the path) to a p...
Definition: CXXInheritance.h:70
clang::MicrosoftVTableContext::getMethodVFTableLocation
MethodVFTableLocation getMethodVFTableLocation(GlobalDecl GD)
Definition: VTableBuilder.cpp:3775
clang
Definition: CalledOnceCheck.h:17
clang::ASTContext::toCharUnitsFromBits
CharUnits toCharUnitsFromBits(int64_t BitSize) const
Convert a size in bits to a size in characters.
Definition: ASTContext.cpp:2460
clang::UniqueVirtualMethod::Subobject
unsigned Subobject
The subobject in which the overriding virtual method resides.
Definition: CXXInheritance.h:236
clang::VTableComponent::getUnusedFunctionDecl
const CXXMethodDecl * getUnusedFunctionDecl() const
Definition: VTableBuilder.h:136
clang::TargetInfo::getPointerWidth
uint64_t getPointerWidth(unsigned AddrSpace) const
Return the width of pointers on this target, for the specified address space.
Definition: TargetInfo.h:424
clang::CXXRecordDecl::bases_begin
base_class_iterator bases_begin()
Definition: DeclCXX.h:603
clang::ThisAdjustment::VirtualAdjustment::VBOffsetOffset
int32_t VBOffsetOffset
The offset (in bytes) of the vbase offset in the vbtable.
Definition: Thunk.h:115
clang::CXXBaseSpecifier
Represents a base class of a C++ class.
Definition: DeclCXX.h:146
clang::FunctionType::getReturnType
QualType getReturnType() const
Definition: Type.h:3880
clang::NamedDecl::getDeclName
DeclarationName getDeclName() const
Get the actual, stored name of the declaration, which may be a special name.
Definition: Decl.h:311
clang::CXXBasePathElement::Base
const CXXBaseSpecifier * Base
The base specifier that states the link from a derived class to a base class, which will be followed ...
Definition: CXXInheritance.h:48
unsigned
clang::CXXRecordDecl::getFinalOverriders
void getFinalOverriders(CXXFinalOverriderMap &FinaOverriders) const
Retrieve the final overriders for each virtual member function in the class hierarchy where this clas...
Definition: CXXInheritance.cpp:642
clang::Dtor_Deleting
@ Dtor_Deleting
Deleting dtor.
Definition: ABI.h:34
clang::PredefinedExpr::PrettyFunctionNoVirtual
@ PrettyFunctionNoVirtual
The same as PrettyFunction, except that the 'virtual' keyword is omitted for virtual member functions...
Definition: Expr.h:1990
clang::VTableContextBase::Thunks
ThunksMapTy Thunks
Contains all thunks that a given method decl will need.
Definition: VTableBuilder.h:333
clang::ASTContext::getASTRecordLayout
const ASTRecordLayout & getASTRecordLayout(const RecordDecl *D) const
Get or compute information about the layout of the specified record (struct/union/class) D,...
Definition: RecordLayoutBuilder.cpp:3270
clang::GlobalDecl::getDecl
const Decl * getDecl() const
Definition: GlobalDecl.h:103
clang::BaseSubobject::getBaseOffset
CharUnits getBaseOffset() const
getBaseOffset - Returns the base class offset.
Definition: BaseSubobject.h:46
clang::ReturnAdjustment::NonVirtual
int64_t NonVirtual
The non-virtual adjustment from the derived object to its nearest virtual base.
Definition: Thunk.h:29
clang::CXXBasePaths
BasePaths - Represents the set of paths from a derived class to one of its (direct or indirect) bases...
Definition: CXXInheritance.h:117
clang::CXXRecordDecl::isDynamicClass
bool isDynamicClass() const
Definition: DeclCXX.h:562
clang::ItaniumVTableContext::~ItaniumVTableContext
~ItaniumVTableContext() override
Definition: VTableBuilder.cpp:2268
clang::CanQual::getAs
CanProxy< U > getAs() const
Retrieve a canonical type pointer with a different static type, upcasting or downcasting as needed.
Definition: CanonicalType.h:653
clang::CXXRecordDecl::isPolymorphic
bool isPolymorphic() const
Whether this class is polymorphic (C++ [class.virtual]), which means that the class contains or inher...
Definition: DeclCXX.h:1169
clang::ReferenceType
Base for LValueReferenceType and RValueReferenceType.
Definition: Type.h:2823
clang::CharUnits
CharUnits - This is an opaque type for sizes expressed in character units.
Definition: CharUnits.h:38
clang::ReturnAdjustment::VirtualAdjustment::VBaseOffsetOffset
int64_t VBaseOffsetOffset
The offset (in bytes), relative to the address point of the virtual base class offset.
Definition: Thunk.h:38
clang::MethodVFTableLocation::VFPtrOffset
CharUnits VFPtrOffset
This is the offset of the vfptr from the start of the last vbase, or the complete type if there are n...
Definition: VTableBuilder.h:520
llvm::SmallVectorImpl
Definition: Randstruct.h:18
clang::ValueDecl::getType
QualType getType() const
Definition: Decl.h:685
llvm::SmallSetVector
Definition: ExternalSemaSource.h:23
clang::ThisAdjustment
A this pointer adjustment.
Definition: Thunk.h:91
clang::NamedDecl::printQualifiedName
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:1612
clang::VTableComponent::MakeCompleteDtor
static VTableComponent MakeCompleteDtor(const CXXDestructorDecl *DD)
Definition: VTableBuilder.h:79
clang::diff::Insert
@ Insert
Definition: ASTDiff.h:31
clang::Decl::getLocation
SourceLocation getLocation() const
Definition: DeclBase.h:425
clang::BaseSubobject::getBase
const CXXRecordDecl * getBase() const
getBase - Returns the base class declaration.
Definition: BaseSubobject.h:43
clang::VirtualBaseInfo
All virtual base related information about a given record decl.
Definition: VTableBuilder.h:500
clang::VTableContextBase::hasVtableSlot
static bool hasVtableSlot(const CXXMethodDecl *MD)
Determine whether this function should be assigned a vtable slot.
Definition: VTableBuilder.cpp:2260
clang::ASTContext::getLangOpts
const LangOptions & getLangOpts() const
Definition: ASTContext.h:786
clang::CharUnits::getQuantity
QuantityType getQuantity() const
getQuantity - Get the raw integer representation of this quantity.
Definition: CharUnits.h:179
clang::MethodVFTableLocation
Definition: VTableBuilder.h:510
clang::ASTContext::getDiagnostics
DiagnosticsEngine & getDiagnostics() const
Definition: ASTContext.cpp:1499
clang::CXXMethodDecl::isVirtual
bool isVirtual() const
Definition: DeclCXX.h:2025
clang::UniqueVirtualMethod::InVirtualSubobject
const CXXRecordDecl * InVirtualSubobject
The virtual base class subobject of which this overridden virtual method is a part.
Definition: CXXInheritance.h:241
RecordLayout.h
clang::CXXBasePathElement::Class
const CXXRecordDecl * Class
The record decl of the class that the base is a base of.
Definition: CXXInheritance.h:51
clang::DiagnosticsEngine::Report
DiagnosticBuilder Report(SourceLocation Loc, unsigned DiagID)
Issue the message to the client.
Definition: Diagnostic.h:1537
clang::CXXMethodDecl::getParent
const CXXRecordDecl * getParent() const
Return the parent of this method declaration, which is the class in which this method is defined.
Definition: DeclCXX.h:2096
clang::CXXMethodDecl
Represents a static or instance method of a struct/union/class.
Definition: DeclCXX.h:1981
findPathsToSubobject
static void findPathsToSubobject(ASTContext &Context, const ASTRecordLayout &MostDerivedLayout, const CXXRecordDecl *RD, CharUnits Offset, BaseSubobject IntroducingObject, FullPathTy &FullPath, std::list< FullPathTy > &Paths)
Definition: VTableBuilder.cpp:3421
clang::VTableContextBase
Definition: VTableBuilder.h:321