clang  8.0.0svn
VTableBuilder.cpp
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1 //===--- VTableBuilder.cpp - C++ vtable layout builder --------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This contains code dealing with generation of the layout of virtual tables.
11 //
12 //===----------------------------------------------------------------------===//
13 
15 #include "clang/AST/ASTContext.h"
18 #include "clang/AST/RecordLayout.h"
19 #include "clang/Basic/TargetInfo.h"
20 #include "llvm/ADT/SetOperations.h"
21 #include "llvm/ADT/SmallPtrSet.h"
22 #include "llvm/Support/Format.h"
23 #include "llvm/Support/raw_ostream.h"
24 #include <algorithm>
25 #include <cstdio>
26 
27 using namespace clang;
28 
29 #define DUMP_OVERRIDERS 0
30 
31 namespace {
32 
33 /// BaseOffset - Represents an offset from a derived class to a direct or
34 /// indirect base class.
35 struct BaseOffset {
36  /// DerivedClass - The derived class.
37  const CXXRecordDecl *DerivedClass;
38 
39  /// VirtualBase - If the path from the derived class to the base class
40  /// involves virtual base classes, this holds the declaration of the last
41  /// virtual base in this path (i.e. closest to the base class).
42  const CXXRecordDecl *VirtualBase;
43 
44  /// NonVirtualOffset - The offset from the derived class to the base class.
45  /// (Or the offset from the virtual base class to the base class, if the
46  /// path from the derived class to the base class involves a virtual base
47  /// class.
48  CharUnits NonVirtualOffset;
49 
50  BaseOffset() : DerivedClass(nullptr), VirtualBase(nullptr),
51  NonVirtualOffset(CharUnits::Zero()) { }
52  BaseOffset(const CXXRecordDecl *DerivedClass,
53  const CXXRecordDecl *VirtualBase, CharUnits NonVirtualOffset)
54  : DerivedClass(DerivedClass), VirtualBase(VirtualBase),
55  NonVirtualOffset(NonVirtualOffset) { }
56 
57  bool isEmpty() const { return NonVirtualOffset.isZero() && !VirtualBase; }
58 };
59 
60 /// FinalOverriders - Contains the final overrider member functions for all
61 /// member functions in the base subobjects of a class.
62 class FinalOverriders {
63 public:
64  /// OverriderInfo - Information about a final overrider.
65  struct OverriderInfo {
66  /// Method - The method decl of the overrider.
67  const CXXMethodDecl *Method;
68 
69  /// VirtualBase - The virtual base class subobject of this overrider.
70  /// Note that this records the closest derived virtual base class subobject.
71  const CXXRecordDecl *VirtualBase;
72 
73  /// Offset - the base offset of the overrider's parent in the layout class.
75 
76  OverriderInfo() : Method(nullptr), VirtualBase(nullptr),
77  Offset(CharUnits::Zero()) { }
78  };
79 
80 private:
81  /// MostDerivedClass - The most derived class for which the final overriders
82  /// are stored.
83  const CXXRecordDecl *MostDerivedClass;
84 
85  /// MostDerivedClassOffset - If we're building final overriders for a
86  /// construction vtable, this holds the offset from the layout class to the
87  /// most derived class.
88  const CharUnits MostDerivedClassOffset;
89 
90  /// LayoutClass - The class we're using for layout information. Will be
91  /// different than the most derived class if the final overriders are for a
92  /// construction vtable.
93  const CXXRecordDecl *LayoutClass;
94 
95  ASTContext &Context;
96 
97  /// MostDerivedClassLayout - the AST record layout of the most derived class.
98  const ASTRecordLayout &MostDerivedClassLayout;
99 
100  /// MethodBaseOffsetPairTy - Uniquely identifies a member function
101  /// in a base subobject.
102  typedef std::pair<const CXXMethodDecl *, CharUnits> MethodBaseOffsetPairTy;
103 
104  typedef llvm::DenseMap<MethodBaseOffsetPairTy,
105  OverriderInfo> OverridersMapTy;
106 
107  /// OverridersMap - The final overriders for all virtual member functions of
108  /// all the base subobjects of the most derived class.
109  OverridersMapTy OverridersMap;
110 
111  /// SubobjectsToOffsetsMapTy - A mapping from a base subobject (represented
112  /// as a record decl and a subobject number) and its offsets in the most
113  /// derived class as well as the layout class.
114  typedef llvm::DenseMap<std::pair<const CXXRecordDecl *, unsigned>,
115  CharUnits> SubobjectOffsetMapTy;
116 
117  typedef llvm::DenseMap<const CXXRecordDecl *, unsigned> SubobjectCountMapTy;
118 
119  /// ComputeBaseOffsets - Compute the offsets for all base subobjects of the
120  /// given base.
121  void ComputeBaseOffsets(BaseSubobject Base, bool IsVirtual,
122  CharUnits OffsetInLayoutClass,
123  SubobjectOffsetMapTy &SubobjectOffsets,
124  SubobjectOffsetMapTy &SubobjectLayoutClassOffsets,
125  SubobjectCountMapTy &SubobjectCounts);
126 
127  typedef llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBasesSetTy;
128 
129  /// dump - dump the final overriders for a base subobject, and all its direct
130  /// and indirect base subobjects.
131  void dump(raw_ostream &Out, BaseSubobject Base,
132  VisitedVirtualBasesSetTy& VisitedVirtualBases);
133 
134 public:
135  FinalOverriders(const CXXRecordDecl *MostDerivedClass,
136  CharUnits MostDerivedClassOffset,
137  const CXXRecordDecl *LayoutClass);
138 
139  /// getOverrider - Get the final overrider for the given method declaration in
140  /// the subobject with the given base offset.
141  OverriderInfo getOverrider(const CXXMethodDecl *MD,
142  CharUnits BaseOffset) const {
143  assert(OverridersMap.count(std::make_pair(MD, BaseOffset)) &&
144  "Did not find overrider!");
145 
146  return OverridersMap.lookup(std::make_pair(MD, BaseOffset));
147  }
148 
149  /// dump - dump the final overriders.
150  void dump() {
151  VisitedVirtualBasesSetTy VisitedVirtualBases;
152  dump(llvm::errs(), BaseSubobject(MostDerivedClass, CharUnits::Zero()),
153  VisitedVirtualBases);
154  }
155 
156 };
157 
158 FinalOverriders::FinalOverriders(const CXXRecordDecl *MostDerivedClass,
159  CharUnits MostDerivedClassOffset,
160  const CXXRecordDecl *LayoutClass)
161  : MostDerivedClass(MostDerivedClass),
162  MostDerivedClassOffset(MostDerivedClassOffset), LayoutClass(LayoutClass),
163  Context(MostDerivedClass->getASTContext()),
164  MostDerivedClassLayout(Context.getASTRecordLayout(MostDerivedClass)) {
165 
166  // Compute base offsets.
167  SubobjectOffsetMapTy SubobjectOffsets;
168  SubobjectOffsetMapTy SubobjectLayoutClassOffsets;
169  SubobjectCountMapTy SubobjectCounts;
170  ComputeBaseOffsets(BaseSubobject(MostDerivedClass, CharUnits::Zero()),
171  /*IsVirtual=*/false,
172  MostDerivedClassOffset,
173  SubobjectOffsets, SubobjectLayoutClassOffsets,
174  SubobjectCounts);
175 
176  // Get the final overriders.
177  CXXFinalOverriderMap FinalOverriders;
178  MostDerivedClass->getFinalOverriders(FinalOverriders);
179 
180  for (const auto &Overrider : FinalOverriders) {
181  const CXXMethodDecl *MD = Overrider.first;
182  const OverridingMethods &Methods = Overrider.second;
183 
184  for (const auto &M : Methods) {
185  unsigned SubobjectNumber = M.first;
186  assert(SubobjectOffsets.count(std::make_pair(MD->getParent(),
187  SubobjectNumber)) &&
188  "Did not find subobject offset!");
189 
190  CharUnits BaseOffset = SubobjectOffsets[std::make_pair(MD->getParent(),
191  SubobjectNumber)];
192 
193  assert(M.second.size() == 1 && "Final overrider is not unique!");
194  const UniqueVirtualMethod &Method = M.second.front();
195 
196  const CXXRecordDecl *OverriderRD = Method.Method->getParent();
197  assert(SubobjectLayoutClassOffsets.count(
198  std::make_pair(OverriderRD, Method.Subobject))
199  && "Did not find subobject offset!");
200  CharUnits OverriderOffset =
201  SubobjectLayoutClassOffsets[std::make_pair(OverriderRD,
202  Method.Subobject)];
203 
204  OverriderInfo& Overrider = OverridersMap[std::make_pair(MD, BaseOffset)];
205  assert(!Overrider.Method && "Overrider should not exist yet!");
206 
207  Overrider.Offset = OverriderOffset;
208  Overrider.Method = Method.Method;
209  Overrider.VirtualBase = Method.InVirtualSubobject;
210  }
211  }
212 
213 #if DUMP_OVERRIDERS
214  // And dump them (for now).
215  dump();
216 #endif
217 }
218 
219 static BaseOffset ComputeBaseOffset(const ASTContext &Context,
220  const CXXRecordDecl *DerivedRD,
221  const CXXBasePath &Path) {
222  CharUnits NonVirtualOffset = CharUnits::Zero();
223 
224  unsigned NonVirtualStart = 0;
225  const CXXRecordDecl *VirtualBase = nullptr;
226 
227  // First, look for the virtual base class.
228  for (int I = Path.size(), E = 0; I != E; --I) {
229  const CXXBasePathElement &Element = Path[I - 1];
230 
231  if (Element.Base->isVirtual()) {
232  NonVirtualStart = I;
233  QualType VBaseType = Element.Base->getType();
234  VirtualBase = VBaseType->getAsCXXRecordDecl();
235  break;
236  }
237  }
238 
239  // Now compute the non-virtual offset.
240  for (unsigned I = NonVirtualStart, E = Path.size(); I != E; ++I) {
241  const CXXBasePathElement &Element = Path[I];
242 
243  // Check the base class offset.
244  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Element.Class);
245 
246  const CXXRecordDecl *Base = Element.Base->getType()->getAsCXXRecordDecl();
247 
248  NonVirtualOffset += Layout.getBaseClassOffset(Base);
249  }
250 
251  // FIXME: This should probably use CharUnits or something. Maybe we should
252  // even change the base offsets in ASTRecordLayout to be specified in
253  // CharUnits.
254  return BaseOffset(DerivedRD, VirtualBase, NonVirtualOffset);
255 
256 }
257 
258 static BaseOffset ComputeBaseOffset(const ASTContext &Context,
259  const CXXRecordDecl *BaseRD,
260  const CXXRecordDecl *DerivedRD) {
261  CXXBasePaths Paths(/*FindAmbiguities=*/false,
262  /*RecordPaths=*/true, /*DetectVirtual=*/false);
263 
264  if (!DerivedRD->isDerivedFrom(BaseRD, Paths))
265  llvm_unreachable("Class must be derived from the passed in base class!");
266 
267  return ComputeBaseOffset(Context, DerivedRD, Paths.front());
268 }
269 
270 static BaseOffset
271 ComputeReturnAdjustmentBaseOffset(ASTContext &Context,
272  const CXXMethodDecl *DerivedMD,
273  const CXXMethodDecl *BaseMD) {
274  const FunctionType *BaseFT = BaseMD->getType()->getAs<FunctionType>();
275  const FunctionType *DerivedFT = DerivedMD->getType()->getAs<FunctionType>();
276 
277  // Canonicalize the return types.
278  CanQualType CanDerivedReturnType =
279  Context.getCanonicalType(DerivedFT->getReturnType());
280  CanQualType CanBaseReturnType =
281  Context.getCanonicalType(BaseFT->getReturnType());
282 
283  assert(CanDerivedReturnType->getTypeClass() ==
284  CanBaseReturnType->getTypeClass() &&
285  "Types must have same type class!");
286 
287  if (CanDerivedReturnType == CanBaseReturnType) {
288  // No adjustment needed.
289  return BaseOffset();
290  }
291 
292  if (isa<ReferenceType>(CanDerivedReturnType)) {
293  CanDerivedReturnType =
294  CanDerivedReturnType->getAs<ReferenceType>()->getPointeeType();
295  CanBaseReturnType =
296  CanBaseReturnType->getAs<ReferenceType>()->getPointeeType();
297  } else if (isa<PointerType>(CanDerivedReturnType)) {
298  CanDerivedReturnType =
299  CanDerivedReturnType->getAs<PointerType>()->getPointeeType();
300  CanBaseReturnType =
301  CanBaseReturnType->getAs<PointerType>()->getPointeeType();
302  } else {
303  llvm_unreachable("Unexpected return type!");
304  }
305 
306  // We need to compare unqualified types here; consider
307  // const T *Base::foo();
308  // T *Derived::foo();
309  if (CanDerivedReturnType.getUnqualifiedType() ==
310  CanBaseReturnType.getUnqualifiedType()) {
311  // No adjustment needed.
312  return BaseOffset();
313  }
314 
315  const CXXRecordDecl *DerivedRD =
316  cast<CXXRecordDecl>(cast<RecordType>(CanDerivedReturnType)->getDecl());
317 
318  const CXXRecordDecl *BaseRD =
319  cast<CXXRecordDecl>(cast<RecordType>(CanBaseReturnType)->getDecl());
320 
321  return ComputeBaseOffset(Context, BaseRD, DerivedRD);
322 }
323 
324 void
325 FinalOverriders::ComputeBaseOffsets(BaseSubobject Base, bool IsVirtual,
326  CharUnits OffsetInLayoutClass,
327  SubobjectOffsetMapTy &SubobjectOffsets,
328  SubobjectOffsetMapTy &SubobjectLayoutClassOffsets,
329  SubobjectCountMapTy &SubobjectCounts) {
330  const CXXRecordDecl *RD = Base.getBase();
331 
332  unsigned SubobjectNumber = 0;
333  if (!IsVirtual)
334  SubobjectNumber = ++SubobjectCounts[RD];
335 
336  // Set up the subobject to offset mapping.
337  assert(!SubobjectOffsets.count(std::make_pair(RD, SubobjectNumber))
338  && "Subobject offset already exists!");
339  assert(!SubobjectLayoutClassOffsets.count(std::make_pair(RD, SubobjectNumber))
340  && "Subobject offset already exists!");
341 
342  SubobjectOffsets[std::make_pair(RD, SubobjectNumber)] = Base.getBaseOffset();
343  SubobjectLayoutClassOffsets[std::make_pair(RD, SubobjectNumber)] =
344  OffsetInLayoutClass;
345 
346  // Traverse our bases.
347  for (const auto &B : RD->bases()) {
348  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
349 
350  CharUnits BaseOffset;
351  CharUnits BaseOffsetInLayoutClass;
352  if (B.isVirtual()) {
353  // Check if we've visited this virtual base before.
354  if (SubobjectOffsets.count(std::make_pair(BaseDecl, 0)))
355  continue;
356 
357  const ASTRecordLayout &LayoutClassLayout =
358  Context.getASTRecordLayout(LayoutClass);
359 
360  BaseOffset = MostDerivedClassLayout.getVBaseClassOffset(BaseDecl);
361  BaseOffsetInLayoutClass =
362  LayoutClassLayout.getVBaseClassOffset(BaseDecl);
363  } else {
364  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
365  CharUnits Offset = Layout.getBaseClassOffset(BaseDecl);
366 
367  BaseOffset = Base.getBaseOffset() + Offset;
368  BaseOffsetInLayoutClass = OffsetInLayoutClass + Offset;
369  }
370 
371  ComputeBaseOffsets(BaseSubobject(BaseDecl, BaseOffset),
372  B.isVirtual(), BaseOffsetInLayoutClass,
373  SubobjectOffsets, SubobjectLayoutClassOffsets,
374  SubobjectCounts);
375  }
376 }
377 
378 void FinalOverriders::dump(raw_ostream &Out, BaseSubobject Base,
379  VisitedVirtualBasesSetTy &VisitedVirtualBases) {
380  const CXXRecordDecl *RD = Base.getBase();
381  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
382 
383  for (const auto &B : RD->bases()) {
384  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
385 
386  // Ignore bases that don't have any virtual member functions.
387  if (!BaseDecl->isPolymorphic())
388  continue;
389 
390  CharUnits BaseOffset;
391  if (B.isVirtual()) {
392  if (!VisitedVirtualBases.insert(BaseDecl).second) {
393  // We've visited this base before.
394  continue;
395  }
396 
397  BaseOffset = MostDerivedClassLayout.getVBaseClassOffset(BaseDecl);
398  } else {
399  BaseOffset = Layout.getBaseClassOffset(BaseDecl) + Base.getBaseOffset();
400  }
401 
402  dump(Out, BaseSubobject(BaseDecl, BaseOffset), VisitedVirtualBases);
403  }
404 
405  Out << "Final overriders for (";
406  RD->printQualifiedName(Out);
407  Out << ", ";
408  Out << Base.getBaseOffset().getQuantity() << ")\n";
409 
410  // Now dump the overriders for this base subobject.
411  for (const auto *MD : RD->methods()) {
412  if (!MD->isVirtual())
413  continue;
414  MD = MD->getCanonicalDecl();
415 
416  OverriderInfo Overrider = getOverrider(MD, Base.getBaseOffset());
417 
418  Out << " ";
419  MD->printQualifiedName(Out);
420  Out << " - (";
421  Overrider.Method->printQualifiedName(Out);
422  Out << ", " << Overrider.Offset.getQuantity() << ')';
423 
424  BaseOffset Offset;
425  if (!Overrider.Method->isPure())
426  Offset = ComputeReturnAdjustmentBaseOffset(Context, Overrider.Method, MD);
427 
428  if (!Offset.isEmpty()) {
429  Out << " [ret-adj: ";
430  if (Offset.VirtualBase) {
431  Offset.VirtualBase->printQualifiedName(Out);
432  Out << " vbase, ";
433  }
434 
435  Out << Offset.NonVirtualOffset.getQuantity() << " nv]";
436  }
437 
438  Out << "\n";
439  }
440 }
441 
442 /// VCallOffsetMap - Keeps track of vcall offsets when building a vtable.
443 struct VCallOffsetMap {
444 
445  typedef std::pair<const CXXMethodDecl *, CharUnits> MethodAndOffsetPairTy;
446 
447  /// Offsets - Keeps track of methods and their offsets.
448  // FIXME: This should be a real map and not a vector.
450 
451  /// MethodsCanShareVCallOffset - Returns whether two virtual member functions
452  /// can share the same vcall offset.
453  static bool MethodsCanShareVCallOffset(const CXXMethodDecl *LHS,
454  const CXXMethodDecl *RHS);
455 
456 public:
457  /// AddVCallOffset - Adds a vcall offset to the map. Returns true if the
458  /// add was successful, or false if there was already a member function with
459  /// the same signature in the map.
460  bool AddVCallOffset(const CXXMethodDecl *MD, CharUnits OffsetOffset);
461 
462  /// getVCallOffsetOffset - Returns the vcall offset offset (relative to the
463  /// vtable address point) for the given virtual member function.
464  CharUnits getVCallOffsetOffset(const CXXMethodDecl *MD);
465 
466  // empty - Return whether the offset map is empty or not.
467  bool empty() const { return Offsets.empty(); }
468 };
469 
470 static bool HasSameVirtualSignature(const CXXMethodDecl *LHS,
471  const CXXMethodDecl *RHS) {
472  const FunctionProtoType *LT =
473  cast<FunctionProtoType>(LHS->getType().getCanonicalType());
474  const FunctionProtoType *RT =
475  cast<FunctionProtoType>(RHS->getType().getCanonicalType());
476 
477  // Fast-path matches in the canonical types.
478  if (LT == RT) return true;
479 
480  // Force the signatures to match. We can't rely on the overrides
481  // list here because there isn't necessarily an inheritance
482  // relationship between the two methods.
483  if (LT->getTypeQuals() != RT->getTypeQuals())
484  return false;
485  return LT->getParamTypes() == RT->getParamTypes();
486 }
487 
488 bool VCallOffsetMap::MethodsCanShareVCallOffset(const CXXMethodDecl *LHS,
489  const CXXMethodDecl *RHS) {
490  assert(LHS->isVirtual() && "LHS must be virtual!");
491  assert(RHS->isVirtual() && "LHS must be virtual!");
492 
493  // A destructor can share a vcall offset with another destructor.
494  if (isa<CXXDestructorDecl>(LHS))
495  return isa<CXXDestructorDecl>(RHS);
496 
497  // FIXME: We need to check more things here.
498 
499  // The methods must have the same name.
500  DeclarationName LHSName = LHS->getDeclName();
501  DeclarationName RHSName = RHS->getDeclName();
502  if (LHSName != RHSName)
503  return false;
504 
505  // And the same signatures.
506  return HasSameVirtualSignature(LHS, RHS);
507 }
508 
509 bool VCallOffsetMap::AddVCallOffset(const CXXMethodDecl *MD,
510  CharUnits OffsetOffset) {
511  // Check if we can reuse an offset.
512  for (const auto &OffsetPair : Offsets) {
513  if (MethodsCanShareVCallOffset(OffsetPair.first, MD))
514  return false;
515  }
516 
517  // Add the offset.
518  Offsets.push_back(MethodAndOffsetPairTy(MD, OffsetOffset));
519  return true;
520 }
521 
522 CharUnits VCallOffsetMap::getVCallOffsetOffset(const CXXMethodDecl *MD) {
523  // Look for an offset.
524  for (const auto &OffsetPair : Offsets) {
525  if (MethodsCanShareVCallOffset(OffsetPair.first, MD))
526  return OffsetPair.second;
527  }
528 
529  llvm_unreachable("Should always find a vcall offset offset!");
530 }
531 
532 /// VCallAndVBaseOffsetBuilder - Class for building vcall and vbase offsets.
533 class VCallAndVBaseOffsetBuilder {
534 public:
535  typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits>
536  VBaseOffsetOffsetsMapTy;
537 
538 private:
539  /// MostDerivedClass - The most derived class for which we're building vcall
540  /// and vbase offsets.
541  const CXXRecordDecl *MostDerivedClass;
542 
543  /// LayoutClass - The class we're using for layout information. Will be
544  /// different than the most derived class if we're building a construction
545  /// vtable.
546  const CXXRecordDecl *LayoutClass;
547 
548  /// Context - The ASTContext which we will use for layout information.
549  ASTContext &Context;
550 
551  /// Components - vcall and vbase offset components
552  typedef SmallVector<VTableComponent, 64> VTableComponentVectorTy;
553  VTableComponentVectorTy Components;
554 
555  /// VisitedVirtualBases - Visited virtual bases.
556  llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBases;
557 
558  /// VCallOffsets - Keeps track of vcall offsets.
559  VCallOffsetMap VCallOffsets;
560 
561 
562  /// VBaseOffsetOffsets - Contains the offsets of the virtual base offsets,
563  /// relative to the address point.
564  VBaseOffsetOffsetsMapTy VBaseOffsetOffsets;
565 
566  /// FinalOverriders - The final overriders of the most derived class.
567  /// (Can be null when we're not building a vtable of the most derived class).
568  const FinalOverriders *Overriders;
569 
570  /// AddVCallAndVBaseOffsets - Add vcall offsets and vbase offsets for the
571  /// given base subobject.
572  void AddVCallAndVBaseOffsets(BaseSubobject Base, bool BaseIsVirtual,
573  CharUnits RealBaseOffset);
574 
575  /// AddVCallOffsets - Add vcall offsets for the given base subobject.
576  void AddVCallOffsets(BaseSubobject Base, CharUnits VBaseOffset);
577 
578  /// AddVBaseOffsets - Add vbase offsets for the given class.
579  void AddVBaseOffsets(const CXXRecordDecl *Base,
580  CharUnits OffsetInLayoutClass);
581 
582  /// getCurrentOffsetOffset - Get the current vcall or vbase offset offset in
583  /// chars, relative to the vtable address point.
584  CharUnits getCurrentOffsetOffset() const;
585 
586 public:
587  VCallAndVBaseOffsetBuilder(const CXXRecordDecl *MostDerivedClass,
588  const CXXRecordDecl *LayoutClass,
589  const FinalOverriders *Overriders,
590  BaseSubobject Base, bool BaseIsVirtual,
591  CharUnits OffsetInLayoutClass)
592  : MostDerivedClass(MostDerivedClass), LayoutClass(LayoutClass),
593  Context(MostDerivedClass->getASTContext()), Overriders(Overriders) {
594 
595  // Add vcall and vbase offsets.
596  AddVCallAndVBaseOffsets(Base, BaseIsVirtual, OffsetInLayoutClass);
597  }
598 
599  /// Methods for iterating over the components.
600  typedef VTableComponentVectorTy::const_reverse_iterator const_iterator;
601  const_iterator components_begin() const { return Components.rbegin(); }
602  const_iterator components_end() const { return Components.rend(); }
603 
604  const VCallOffsetMap &getVCallOffsets() const { return VCallOffsets; }
605  const VBaseOffsetOffsetsMapTy &getVBaseOffsetOffsets() const {
606  return VBaseOffsetOffsets;
607  }
608 };
609 
610 void
611 VCallAndVBaseOffsetBuilder::AddVCallAndVBaseOffsets(BaseSubobject Base,
612  bool BaseIsVirtual,
613  CharUnits RealBaseOffset) {
614  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base.getBase());
615 
616  // Itanium C++ ABI 2.5.2:
617  // ..in classes sharing a virtual table with a primary base class, the vcall
618  // and vbase offsets added by the derived class all come before the vcall
619  // and vbase offsets required by the base class, so that the latter may be
620  // laid out as required by the base class without regard to additions from
621  // the derived class(es).
622 
623  // (Since we're emitting the vcall and vbase offsets in reverse order, we'll
624  // emit them for the primary base first).
625  if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
626  bool PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual();
627 
628  CharUnits PrimaryBaseOffset;
629 
630  // Get the base offset of the primary base.
631  if (PrimaryBaseIsVirtual) {
632  assert(Layout.getVBaseClassOffset(PrimaryBase).isZero() &&
633  "Primary vbase should have a zero offset!");
634 
635  const ASTRecordLayout &MostDerivedClassLayout =
636  Context.getASTRecordLayout(MostDerivedClass);
637 
638  PrimaryBaseOffset =
639  MostDerivedClassLayout.getVBaseClassOffset(PrimaryBase);
640  } else {
641  assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
642  "Primary base should have a zero offset!");
643 
644  PrimaryBaseOffset = Base.getBaseOffset();
645  }
646 
647  AddVCallAndVBaseOffsets(
648  BaseSubobject(PrimaryBase,PrimaryBaseOffset),
649  PrimaryBaseIsVirtual, RealBaseOffset);
650  }
651 
652  AddVBaseOffsets(Base.getBase(), RealBaseOffset);
653 
654  // We only want to add vcall offsets for virtual bases.
655  if (BaseIsVirtual)
656  AddVCallOffsets(Base, RealBaseOffset);
657 }
658 
659 CharUnits VCallAndVBaseOffsetBuilder::getCurrentOffsetOffset() const {
660  // OffsetIndex is the index of this vcall or vbase offset, relative to the
661  // vtable address point. (We subtract 3 to account for the information just
662  // above the address point, the RTTI info, the offset to top, and the
663  // vcall offset itself).
664  int64_t OffsetIndex = -(int64_t)(3 + Components.size());
665 
666  CharUnits PointerWidth =
667  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
668  CharUnits OffsetOffset = PointerWidth * OffsetIndex;
669  return OffsetOffset;
670 }
671 
672 void VCallAndVBaseOffsetBuilder::AddVCallOffsets(BaseSubobject Base,
673  CharUnits VBaseOffset) {
674  const CXXRecordDecl *RD = Base.getBase();
675  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
676 
677  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
678 
679  // Handle the primary base first.
680  // We only want to add vcall offsets if the base is non-virtual; a virtual
681  // primary base will have its vcall and vbase offsets emitted already.
682  if (PrimaryBase && !Layout.isPrimaryBaseVirtual()) {
683  // Get the base offset of the primary base.
684  assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
685  "Primary base should have a zero offset!");
686 
687  AddVCallOffsets(BaseSubobject(PrimaryBase, Base.getBaseOffset()),
688  VBaseOffset);
689  }
690 
691  // Add the vcall offsets.
692  for (const auto *MD : RD->methods()) {
693  if (!MD->isVirtual())
694  continue;
695  MD = MD->getCanonicalDecl();
696 
697  CharUnits OffsetOffset = getCurrentOffsetOffset();
698 
699  // Don't add a vcall offset if we already have one for this member function
700  // signature.
701  if (!VCallOffsets.AddVCallOffset(MD, OffsetOffset))
702  continue;
703 
705 
706  if (Overriders) {
707  // Get the final overrider.
708  FinalOverriders::OverriderInfo Overrider =
709  Overriders->getOverrider(MD, Base.getBaseOffset());
710 
711  /// The vcall offset is the offset from the virtual base to the object
712  /// where the function was overridden.
713  Offset = Overrider.Offset - VBaseOffset;
714  }
715 
716  Components.push_back(
718  }
719 
720  // And iterate over all non-virtual bases (ignoring the primary base).
721  for (const auto &B : RD->bases()) {
722  if (B.isVirtual())
723  continue;
724 
725  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
726  if (BaseDecl == PrimaryBase)
727  continue;
728 
729  // Get the base offset of this base.
730  CharUnits BaseOffset = Base.getBaseOffset() +
731  Layout.getBaseClassOffset(BaseDecl);
732 
733  AddVCallOffsets(BaseSubobject(BaseDecl, BaseOffset),
734  VBaseOffset);
735  }
736 }
737 
738 void
739 VCallAndVBaseOffsetBuilder::AddVBaseOffsets(const CXXRecordDecl *RD,
740  CharUnits OffsetInLayoutClass) {
741  const ASTRecordLayout &LayoutClassLayout =
742  Context.getASTRecordLayout(LayoutClass);
743 
744  // Add vbase offsets.
745  for (const auto &B : RD->bases()) {
746  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
747 
748  // Check if this is a virtual base that we haven't visited before.
749  if (B.isVirtual() && VisitedVirtualBases.insert(BaseDecl).second) {
750  CharUnits Offset =
751  LayoutClassLayout.getVBaseClassOffset(BaseDecl) - OffsetInLayoutClass;
752 
753  // Add the vbase offset offset.
754  assert(!VBaseOffsetOffsets.count(BaseDecl) &&
755  "vbase offset offset already exists!");
756 
757  CharUnits VBaseOffsetOffset = getCurrentOffsetOffset();
758  VBaseOffsetOffsets.insert(
759  std::make_pair(BaseDecl, VBaseOffsetOffset));
760 
761  Components.push_back(
763  }
764 
765  // Check the base class looking for more vbase offsets.
766  AddVBaseOffsets(BaseDecl, OffsetInLayoutClass);
767  }
768 }
769 
770 /// ItaniumVTableBuilder - Class for building vtable layout information.
771 class ItaniumVTableBuilder {
772 public:
773  /// PrimaryBasesSetVectorTy - A set vector of direct and indirect
774  /// primary bases.
776  PrimaryBasesSetVectorTy;
777 
778  typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits>
779  VBaseOffsetOffsetsMapTy;
780 
781  typedef VTableLayout::AddressPointsMapTy AddressPointsMapTy;
782 
783  typedef llvm::DenseMap<GlobalDecl, int64_t> MethodVTableIndicesTy;
784 
785 private:
786  /// VTables - Global vtable information.
787  ItaniumVTableContext &VTables;
788 
789  /// MostDerivedClass - The most derived class for which we're building this
790  /// vtable.
791  const CXXRecordDecl *MostDerivedClass;
792 
793  /// MostDerivedClassOffset - If we're building a construction vtable, this
794  /// holds the offset from the layout class to the most derived class.
795  const CharUnits MostDerivedClassOffset;
796 
797  /// MostDerivedClassIsVirtual - Whether the most derived class is a virtual
798  /// base. (This only makes sense when building a construction vtable).
799  bool MostDerivedClassIsVirtual;
800 
801  /// LayoutClass - The class we're using for layout information. Will be
802  /// different than the most derived class if we're building a construction
803  /// vtable.
804  const CXXRecordDecl *LayoutClass;
805 
806  /// Context - The ASTContext which we will use for layout information.
807  ASTContext &Context;
808 
809  /// FinalOverriders - The final overriders of the most derived class.
810  const FinalOverriders Overriders;
811 
812  /// VCallOffsetsForVBases - Keeps track of vcall offsets for the virtual
813  /// bases in this vtable.
814  llvm::DenseMap<const CXXRecordDecl *, VCallOffsetMap> VCallOffsetsForVBases;
815 
816  /// VBaseOffsetOffsets - Contains the offsets of the virtual base offsets for
817  /// the most derived class.
818  VBaseOffsetOffsetsMapTy VBaseOffsetOffsets;
819 
820  /// Components - The components of the vtable being built.
822 
823  /// AddressPoints - Address points for the vtable being built.
824  AddressPointsMapTy AddressPoints;
825 
826  /// MethodInfo - Contains information about a method in a vtable.
827  /// (Used for computing 'this' pointer adjustment thunks.
828  struct MethodInfo {
829  /// BaseOffset - The base offset of this method.
830  const CharUnits BaseOffset;
831 
832  /// BaseOffsetInLayoutClass - The base offset in the layout class of this
833  /// method.
834  const CharUnits BaseOffsetInLayoutClass;
835 
836  /// VTableIndex - The index in the vtable that this method has.
837  /// (For destructors, this is the index of the complete destructor).
838  const uint64_t VTableIndex;
839 
840  MethodInfo(CharUnits BaseOffset, CharUnits BaseOffsetInLayoutClass,
841  uint64_t VTableIndex)
842  : BaseOffset(BaseOffset),
843  BaseOffsetInLayoutClass(BaseOffsetInLayoutClass),
844  VTableIndex(VTableIndex) { }
845 
846  MethodInfo()
847  : BaseOffset(CharUnits::Zero()),
848  BaseOffsetInLayoutClass(CharUnits::Zero()),
849  VTableIndex(0) { }
850  };
851 
852  typedef llvm::DenseMap<const CXXMethodDecl *, MethodInfo> MethodInfoMapTy;
853 
854  /// MethodInfoMap - The information for all methods in the vtable we're
855  /// currently building.
856  MethodInfoMapTy MethodInfoMap;
857 
858  /// MethodVTableIndices - Contains the index (relative to the vtable address
859  /// point) where the function pointer for a virtual function is stored.
860  MethodVTableIndicesTy MethodVTableIndices;
861 
862  typedef llvm::DenseMap<uint64_t, ThunkInfo> VTableThunksMapTy;
863 
864  /// VTableThunks - The thunks by vtable index in the vtable currently being
865  /// built.
866  VTableThunksMapTy VTableThunks;
867 
868  typedef SmallVector<ThunkInfo, 1> ThunkInfoVectorTy;
869  typedef llvm::DenseMap<const CXXMethodDecl *, ThunkInfoVectorTy> ThunksMapTy;
870 
871  /// Thunks - A map that contains all the thunks needed for all methods in the
872  /// most derived class for which the vtable is currently being built.
873  ThunksMapTy Thunks;
874 
875  /// AddThunk - Add a thunk for the given method.
876  void AddThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk);
877 
878  /// ComputeThisAdjustments - Compute the 'this' pointer adjustments for the
879  /// part of the vtable we're currently building.
880  void ComputeThisAdjustments();
881 
882  typedef llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBasesSetTy;
883 
884  /// PrimaryVirtualBases - All known virtual bases who are a primary base of
885  /// some other base.
886  VisitedVirtualBasesSetTy PrimaryVirtualBases;
887 
888  /// ComputeReturnAdjustment - Compute the return adjustment given a return
889  /// adjustment base offset.
890  ReturnAdjustment ComputeReturnAdjustment(BaseOffset Offset);
891 
892  /// ComputeThisAdjustmentBaseOffset - Compute the base offset for adjusting
893  /// the 'this' pointer from the base subobject to the derived subobject.
894  BaseOffset ComputeThisAdjustmentBaseOffset(BaseSubobject Base,
895  BaseSubobject Derived) const;
896 
897  /// ComputeThisAdjustment - Compute the 'this' pointer adjustment for the
898  /// given virtual member function, its offset in the layout class and its
899  /// final overrider.
901  ComputeThisAdjustment(const CXXMethodDecl *MD,
902  CharUnits BaseOffsetInLayoutClass,
903  FinalOverriders::OverriderInfo Overrider);
904 
905  /// AddMethod - Add a single virtual member function to the vtable
906  /// components vector.
907  void AddMethod(const CXXMethodDecl *MD, ReturnAdjustment ReturnAdjustment);
908 
909  /// IsOverriderUsed - Returns whether the overrider will ever be used in this
910  /// part of the vtable.
911  ///
912  /// Itanium C++ ABI 2.5.2:
913  ///
914  /// struct A { virtual void f(); };
915  /// struct B : virtual public A { int i; };
916  /// struct C : virtual public A { int j; };
917  /// struct D : public B, public C {};
918  ///
919  /// When B and C are declared, A is a primary base in each case, so although
920  /// vcall offsets are allocated in the A-in-B and A-in-C vtables, no this
921  /// adjustment is required and no thunk is generated. However, inside D
922  /// objects, A is no longer a primary base of C, so if we allowed calls to
923  /// C::f() to use the copy of A's vtable in the C subobject, we would need
924  /// to adjust this from C* to B::A*, which would require a third-party
925  /// thunk. Since we require that a call to C::f() first convert to A*,
926  /// C-in-D's copy of A's vtable is never referenced, so this is not
927  /// necessary.
928  bool IsOverriderUsed(const CXXMethodDecl *Overrider,
929  CharUnits BaseOffsetInLayoutClass,
930  const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
931  CharUnits FirstBaseOffsetInLayoutClass) const;
932 
933 
934  /// AddMethods - Add the methods of this base subobject and all its
935  /// primary bases to the vtable components vector.
936  void AddMethods(BaseSubobject Base, CharUnits BaseOffsetInLayoutClass,
937  const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
938  CharUnits FirstBaseOffsetInLayoutClass,
939  PrimaryBasesSetVectorTy &PrimaryBases);
940 
941  // LayoutVTable - Layout the vtable for the given base class, including its
942  // secondary vtables and any vtables for virtual bases.
943  void LayoutVTable();
944 
945  /// LayoutPrimaryAndSecondaryVTables - Layout the primary vtable for the
946  /// given base subobject, as well as all its secondary vtables.
947  ///
948  /// \param BaseIsMorallyVirtual whether the base subobject is a virtual base
949  /// or a direct or indirect base of a virtual base.
950  ///
951  /// \param BaseIsVirtualInLayoutClass - Whether the base subobject is virtual
952  /// in the layout class.
953  void LayoutPrimaryAndSecondaryVTables(BaseSubobject Base,
954  bool BaseIsMorallyVirtual,
955  bool BaseIsVirtualInLayoutClass,
956  CharUnits OffsetInLayoutClass);
957 
958  /// LayoutSecondaryVTables - Layout the secondary vtables for the given base
959  /// subobject.
960  ///
961  /// \param BaseIsMorallyVirtual whether the base subobject is a virtual base
962  /// or a direct or indirect base of a virtual base.
963  void LayoutSecondaryVTables(BaseSubobject Base, bool BaseIsMorallyVirtual,
964  CharUnits OffsetInLayoutClass);
965 
966  /// DeterminePrimaryVirtualBases - Determine the primary virtual bases in this
967  /// class hierarchy.
968  void DeterminePrimaryVirtualBases(const CXXRecordDecl *RD,
969  CharUnits OffsetInLayoutClass,
970  VisitedVirtualBasesSetTy &VBases);
971 
972  /// LayoutVTablesForVirtualBases - Layout vtables for all virtual bases of the
973  /// given base (excluding any primary bases).
974  void LayoutVTablesForVirtualBases(const CXXRecordDecl *RD,
975  VisitedVirtualBasesSetTy &VBases);
976 
977  /// isBuildingConstructionVTable - Return whether this vtable builder is
978  /// building a construction vtable.
979  bool isBuildingConstructorVTable() const {
980  return MostDerivedClass != LayoutClass;
981  }
982 
983 public:
984  /// Component indices of the first component of each of the vtables in the
985  /// vtable group.
986  SmallVector<size_t, 4> VTableIndices;
987 
988  ItaniumVTableBuilder(ItaniumVTableContext &VTables,
989  const CXXRecordDecl *MostDerivedClass,
990  CharUnits MostDerivedClassOffset,
991  bool MostDerivedClassIsVirtual,
992  const CXXRecordDecl *LayoutClass)
993  : VTables(VTables), MostDerivedClass(MostDerivedClass),
994  MostDerivedClassOffset(MostDerivedClassOffset),
995  MostDerivedClassIsVirtual(MostDerivedClassIsVirtual),
996  LayoutClass(LayoutClass), Context(MostDerivedClass->getASTContext()),
997  Overriders(MostDerivedClass, MostDerivedClassOffset, LayoutClass) {
998  assert(!Context.getTargetInfo().getCXXABI().isMicrosoft());
999 
1000  LayoutVTable();
1001 
1002  if (Context.getLangOpts().DumpVTableLayouts)
1003  dumpLayout(llvm::outs());
1004  }
1005 
1006  uint64_t getNumThunks() const {
1007  return Thunks.size();
1008  }
1009 
1010  ThunksMapTy::const_iterator thunks_begin() const {
1011  return Thunks.begin();
1012  }
1013 
1014  ThunksMapTy::const_iterator thunks_end() const {
1015  return Thunks.end();
1016  }
1017 
1018  const VBaseOffsetOffsetsMapTy &getVBaseOffsetOffsets() const {
1019  return VBaseOffsetOffsets;
1020  }
1021 
1022  const AddressPointsMapTy &getAddressPoints() const {
1023  return AddressPoints;
1024  }
1025 
1026  MethodVTableIndicesTy::const_iterator vtable_indices_begin() const {
1027  return MethodVTableIndices.begin();
1028  }
1029 
1030  MethodVTableIndicesTy::const_iterator vtable_indices_end() const {
1031  return MethodVTableIndices.end();
1032  }
1033 
1034  ArrayRef<VTableComponent> vtable_components() const { return Components; }
1035 
1036  AddressPointsMapTy::const_iterator address_points_begin() const {
1037  return AddressPoints.begin();
1038  }
1039 
1040  AddressPointsMapTy::const_iterator address_points_end() const {
1041  return AddressPoints.end();
1042  }
1043 
1044  VTableThunksMapTy::const_iterator vtable_thunks_begin() const {
1045  return VTableThunks.begin();
1046  }
1047 
1048  VTableThunksMapTy::const_iterator vtable_thunks_end() const {
1049  return VTableThunks.end();
1050  }
1051 
1052  /// dumpLayout - Dump the vtable layout.
1053  void dumpLayout(raw_ostream&);
1054 };
1055 
1056 void ItaniumVTableBuilder::AddThunk(const CXXMethodDecl *MD,
1057  const ThunkInfo &Thunk) {
1058  assert(!isBuildingConstructorVTable() &&
1059  "Can't add thunks for construction vtable");
1060 
1061  SmallVectorImpl<ThunkInfo> &ThunksVector = Thunks[MD];
1062 
1063  // Check if we have this thunk already.
1064  if (std::find(ThunksVector.begin(), ThunksVector.end(), Thunk) !=
1065  ThunksVector.end())
1066  return;
1067 
1068  ThunksVector.push_back(Thunk);
1069 }
1070 
1071 typedef llvm::SmallPtrSet<const CXXMethodDecl *, 8> OverriddenMethodsSetTy;
1072 
1073 /// Visit all the methods overridden by the given method recursively,
1074 /// in a depth-first pre-order. The Visitor's visitor method returns a bool
1075 /// indicating whether to continue the recursion for the given overridden
1076 /// method (i.e. returning false stops the iteration).
1077 template <class VisitorTy>
1078 static void
1079 visitAllOverriddenMethods(const CXXMethodDecl *MD, VisitorTy &Visitor) {
1080  assert(MD->isVirtual() && "Method is not virtual!");
1081 
1082  for (const CXXMethodDecl *OverriddenMD : MD->overridden_methods()) {
1083  if (!Visitor(OverriddenMD))
1084  continue;
1085  visitAllOverriddenMethods(OverriddenMD, Visitor);
1086  }
1087 }
1088 
1089 /// ComputeAllOverriddenMethods - Given a method decl, will return a set of all
1090 /// the overridden methods that the function decl overrides.
1091 static void
1092 ComputeAllOverriddenMethods(const CXXMethodDecl *MD,
1093  OverriddenMethodsSetTy& OverriddenMethods) {
1094  auto OverriddenMethodsCollector = [&](const CXXMethodDecl *MD) {
1095  // Don't recurse on this method if we've already collected it.
1096  return OverriddenMethods.insert(MD).second;
1097  };
1098  visitAllOverriddenMethods(MD, OverriddenMethodsCollector);
1099 }
1100 
1101 void ItaniumVTableBuilder::ComputeThisAdjustments() {
1102  // Now go through the method info map and see if any of the methods need
1103  // 'this' pointer adjustments.
1104  for (const auto &MI : MethodInfoMap) {
1105  const CXXMethodDecl *MD = MI.first;
1106  const MethodInfo &MethodInfo = MI.second;
1107 
1108  // Ignore adjustments for unused function pointers.
1109  uint64_t VTableIndex = MethodInfo.VTableIndex;
1110  if (Components[VTableIndex].getKind() ==
1112  continue;
1113 
1114  // Get the final overrider for this method.
1115  FinalOverriders::OverriderInfo Overrider =
1116  Overriders.getOverrider(MD, MethodInfo.BaseOffset);
1117 
1118  // Check if we need an adjustment at all.
1119  if (MethodInfo.BaseOffsetInLayoutClass == Overrider.Offset) {
1120  // When a return thunk is needed by a derived class that overrides a
1121  // virtual base, gcc uses a virtual 'this' adjustment as well.
1122  // While the thunk itself might be needed by vtables in subclasses or
1123  // in construction vtables, there doesn't seem to be a reason for using
1124  // the thunk in this vtable. Still, we do so to match gcc.
1125  if (VTableThunks.lookup(VTableIndex).Return.isEmpty())
1126  continue;
1127  }
1128 
1130  ComputeThisAdjustment(MD, MethodInfo.BaseOffsetInLayoutClass, Overrider);
1131 
1132  if (ThisAdjustment.isEmpty())
1133  continue;
1134 
1135  // Add it.
1136  VTableThunks[VTableIndex].This = ThisAdjustment;
1137 
1138  if (isa<CXXDestructorDecl>(MD)) {
1139  // Add an adjustment for the deleting destructor as well.
1140  VTableThunks[VTableIndex + 1].This = ThisAdjustment;
1141  }
1142  }
1143 
1144  /// Clear the method info map.
1145  MethodInfoMap.clear();
1146 
1147  if (isBuildingConstructorVTable()) {
1148  // We don't need to store thunk information for construction vtables.
1149  return;
1150  }
1151 
1152  for (const auto &TI : VTableThunks) {
1153  const VTableComponent &Component = Components[TI.first];
1154  const ThunkInfo &Thunk = TI.second;
1155  const CXXMethodDecl *MD;
1156 
1157  switch (Component.getKind()) {
1158  default:
1159  llvm_unreachable("Unexpected vtable component kind!");
1161  MD = Component.getFunctionDecl();
1162  break;
1164  MD = Component.getDestructorDecl();
1165  break;
1167  // We've already added the thunk when we saw the complete dtor pointer.
1168  continue;
1169  }
1170 
1171  if (MD->getParent() == MostDerivedClass)
1172  AddThunk(MD, Thunk);
1173  }
1174 }
1175 
1177 ItaniumVTableBuilder::ComputeReturnAdjustment(BaseOffset Offset) {
1178  ReturnAdjustment Adjustment;
1179 
1180  if (!Offset.isEmpty()) {
1181  if (Offset.VirtualBase) {
1182  // Get the virtual base offset offset.
1183  if (Offset.DerivedClass == MostDerivedClass) {
1184  // We can get the offset offset directly from our map.
1185  Adjustment.Virtual.Itanium.VBaseOffsetOffset =
1186  VBaseOffsetOffsets.lookup(Offset.VirtualBase).getQuantity();
1187  } else {
1188  Adjustment.Virtual.Itanium.VBaseOffsetOffset =
1189  VTables.getVirtualBaseOffsetOffset(Offset.DerivedClass,
1190  Offset.VirtualBase).getQuantity();
1191  }
1192  }
1193 
1194  Adjustment.NonVirtual = Offset.NonVirtualOffset.getQuantity();
1195  }
1196 
1197  return Adjustment;
1198 }
1199 
1200 BaseOffset ItaniumVTableBuilder::ComputeThisAdjustmentBaseOffset(
1201  BaseSubobject Base, BaseSubobject Derived) const {
1202  const CXXRecordDecl *BaseRD = Base.getBase();
1203  const CXXRecordDecl *DerivedRD = Derived.getBase();
1204 
1205  CXXBasePaths Paths(/*FindAmbiguities=*/true,
1206  /*RecordPaths=*/true, /*DetectVirtual=*/true);
1207 
1208  if (!DerivedRD->isDerivedFrom(BaseRD, Paths))
1209  llvm_unreachable("Class must be derived from the passed in base class!");
1210 
1211  // We have to go through all the paths, and see which one leads us to the
1212  // right base subobject.
1213  for (const CXXBasePath &Path : Paths) {
1214  BaseOffset Offset = ComputeBaseOffset(Context, DerivedRD, Path);
1215 
1216  CharUnits OffsetToBaseSubobject = Offset.NonVirtualOffset;
1217 
1218  if (Offset.VirtualBase) {
1219  // If we have a virtual base class, the non-virtual offset is relative
1220  // to the virtual base class offset.
1221  const ASTRecordLayout &LayoutClassLayout =
1222  Context.getASTRecordLayout(LayoutClass);
1223 
1224  /// Get the virtual base offset, relative to the most derived class
1225  /// layout.
1226  OffsetToBaseSubobject +=
1227  LayoutClassLayout.getVBaseClassOffset(Offset.VirtualBase);
1228  } else {
1229  // Otherwise, the non-virtual offset is relative to the derived class
1230  // offset.
1231  OffsetToBaseSubobject += Derived.getBaseOffset();
1232  }
1233 
1234  // Check if this path gives us the right base subobject.
1235  if (OffsetToBaseSubobject == Base.getBaseOffset()) {
1236  // Since we're going from the base class _to_ the derived class, we'll
1237  // invert the non-virtual offset here.
1238  Offset.NonVirtualOffset = -Offset.NonVirtualOffset;
1239  return Offset;
1240  }
1241  }
1242 
1243  return BaseOffset();
1244 }
1245 
1246 ThisAdjustment ItaniumVTableBuilder::ComputeThisAdjustment(
1247  const CXXMethodDecl *MD, CharUnits BaseOffsetInLayoutClass,
1248  FinalOverriders::OverriderInfo Overrider) {
1249  // Ignore adjustments for pure virtual member functions.
1250  if (Overrider.Method->isPure())
1251  return ThisAdjustment();
1252 
1253  BaseSubobject OverriddenBaseSubobject(MD->getParent(),
1254  BaseOffsetInLayoutClass);
1255 
1256  BaseSubobject OverriderBaseSubobject(Overrider.Method->getParent(),
1257  Overrider.Offset);
1258 
1259  // Compute the adjustment offset.
1260  BaseOffset Offset = ComputeThisAdjustmentBaseOffset(OverriddenBaseSubobject,
1261  OverriderBaseSubobject);
1262  if (Offset.isEmpty())
1263  return ThisAdjustment();
1264 
1265  ThisAdjustment Adjustment;
1266 
1267  if (Offset.VirtualBase) {
1268  // Get the vcall offset map for this virtual base.
1269  VCallOffsetMap &VCallOffsets = VCallOffsetsForVBases[Offset.VirtualBase];
1270 
1271  if (VCallOffsets.empty()) {
1272  // We don't have vcall offsets for this virtual base, go ahead and
1273  // build them.
1274  VCallAndVBaseOffsetBuilder Builder(MostDerivedClass, MostDerivedClass,
1275  /*FinalOverriders=*/nullptr,
1276  BaseSubobject(Offset.VirtualBase,
1277  CharUnits::Zero()),
1278  /*BaseIsVirtual=*/true,
1279  /*OffsetInLayoutClass=*/
1280  CharUnits::Zero());
1281 
1282  VCallOffsets = Builder.getVCallOffsets();
1283  }
1284 
1285  Adjustment.Virtual.Itanium.VCallOffsetOffset =
1286  VCallOffsets.getVCallOffsetOffset(MD).getQuantity();
1287  }
1288 
1289  // Set the non-virtual part of the adjustment.
1290  Adjustment.NonVirtual = Offset.NonVirtualOffset.getQuantity();
1291 
1292  return Adjustment;
1293 }
1294 
1295 void ItaniumVTableBuilder::AddMethod(const CXXMethodDecl *MD,
1297  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1298  assert(ReturnAdjustment.isEmpty() &&
1299  "Destructor can't have return adjustment!");
1300 
1301  // Add both the complete destructor and the deleting destructor.
1302  Components.push_back(VTableComponent::MakeCompleteDtor(DD));
1303  Components.push_back(VTableComponent::MakeDeletingDtor(DD));
1304  } else {
1305  // Add the return adjustment if necessary.
1306  if (!ReturnAdjustment.isEmpty())
1307  VTableThunks[Components.size()].Return = ReturnAdjustment;
1308 
1309  // Add the function.
1310  Components.push_back(VTableComponent::MakeFunction(MD));
1311  }
1312 }
1313 
1314 /// OverridesIndirectMethodInBase - Return whether the given member function
1315 /// overrides any methods in the set of given bases.
1316 /// Unlike OverridesMethodInBase, this checks "overriders of overriders".
1317 /// For example, if we have:
1318 ///
1319 /// struct A { virtual void f(); }
1320 /// struct B : A { virtual void f(); }
1321 /// struct C : B { virtual void f(); }
1322 ///
1323 /// OverridesIndirectMethodInBase will return true if given C::f as the method
1324 /// and { A } as the set of bases.
1325 static bool OverridesIndirectMethodInBases(
1326  const CXXMethodDecl *MD,
1328  if (Bases.count(MD->getParent()))
1329  return true;
1330 
1331  for (const CXXMethodDecl *OverriddenMD : MD->overridden_methods()) {
1332  // Check "indirect overriders".
1333  if (OverridesIndirectMethodInBases(OverriddenMD, Bases))
1334  return true;
1335  }
1336 
1337  return false;
1338 }
1339 
1340 bool ItaniumVTableBuilder::IsOverriderUsed(
1341  const CXXMethodDecl *Overrider, CharUnits BaseOffsetInLayoutClass,
1342  const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
1343  CharUnits FirstBaseOffsetInLayoutClass) const {
1344  // If the base and the first base in the primary base chain have the same
1345  // offsets, then this overrider will be used.
1346  if (BaseOffsetInLayoutClass == FirstBaseOffsetInLayoutClass)
1347  return true;
1348 
1349  // We know now that Base (or a direct or indirect base of it) is a primary
1350  // base in part of the class hierarchy, but not a primary base in the most
1351  // derived class.
1352 
1353  // If the overrider is the first base in the primary base chain, we know
1354  // that the overrider will be used.
1355  if (Overrider->getParent() == FirstBaseInPrimaryBaseChain)
1356  return true;
1357 
1359 
1360  const CXXRecordDecl *RD = FirstBaseInPrimaryBaseChain;
1361  PrimaryBases.insert(RD);
1362 
1363  // Now traverse the base chain, starting with the first base, until we find
1364  // the base that is no longer a primary base.
1365  while (true) {
1366  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1367  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
1368 
1369  if (!PrimaryBase)
1370  break;
1371 
1372  if (Layout.isPrimaryBaseVirtual()) {
1373  assert(Layout.getVBaseClassOffset(PrimaryBase).isZero() &&
1374  "Primary base should always be at offset 0!");
1375 
1376  const ASTRecordLayout &LayoutClassLayout =
1377  Context.getASTRecordLayout(LayoutClass);
1378 
1379  // Now check if this is the primary base that is not a primary base in the
1380  // most derived class.
1381  if (LayoutClassLayout.getVBaseClassOffset(PrimaryBase) !=
1382  FirstBaseOffsetInLayoutClass) {
1383  // We found it, stop walking the chain.
1384  break;
1385  }
1386  } else {
1387  assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
1388  "Primary base should always be at offset 0!");
1389  }
1390 
1391  if (!PrimaryBases.insert(PrimaryBase))
1392  llvm_unreachable("Found a duplicate primary base!");
1393 
1394  RD = PrimaryBase;
1395  }
1396 
1397  // If the final overrider is an override of one of the primary bases,
1398  // then we know that it will be used.
1399  return OverridesIndirectMethodInBases(Overrider, PrimaryBases);
1400 }
1401 
1402 typedef llvm::SmallSetVector<const CXXRecordDecl *, 8> BasesSetVectorTy;
1403 
1404 /// FindNearestOverriddenMethod - Given a method, returns the overridden method
1405 /// from the nearest base. Returns null if no method was found.
1406 /// The Bases are expected to be sorted in a base-to-derived order.
1407 static const CXXMethodDecl *
1408 FindNearestOverriddenMethod(const CXXMethodDecl *MD,
1409  BasesSetVectorTy &Bases) {
1410  OverriddenMethodsSetTy OverriddenMethods;
1411  ComputeAllOverriddenMethods(MD, OverriddenMethods);
1412 
1413  for (const CXXRecordDecl *PrimaryBase :
1414  llvm::make_range(Bases.rbegin(), Bases.rend())) {
1415  // Now check the overridden methods.
1416  for (const CXXMethodDecl *OverriddenMD : OverriddenMethods) {
1417  // We found our overridden method.
1418  if (OverriddenMD->getParent() == PrimaryBase)
1419  return OverriddenMD;
1420  }
1421  }
1422 
1423  return nullptr;
1424 }
1425 
1426 void ItaniumVTableBuilder::AddMethods(
1427  BaseSubobject Base, CharUnits BaseOffsetInLayoutClass,
1428  const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
1429  CharUnits FirstBaseOffsetInLayoutClass,
1430  PrimaryBasesSetVectorTy &PrimaryBases) {
1431  // Itanium C++ ABI 2.5.2:
1432  // The order of the virtual function pointers in a virtual table is the
1433  // order of declaration of the corresponding member functions in the class.
1434  //
1435  // There is an entry for any virtual function declared in a class,
1436  // whether it is a new function or overrides a base class function,
1437  // unless it overrides a function from the primary base, and conversion
1438  // between their return types does not require an adjustment.
1439 
1440  const CXXRecordDecl *RD = Base.getBase();
1441  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1442 
1443  if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
1444  CharUnits PrimaryBaseOffset;
1445  CharUnits PrimaryBaseOffsetInLayoutClass;
1446  if (Layout.isPrimaryBaseVirtual()) {
1447  assert(Layout.getVBaseClassOffset(PrimaryBase).isZero() &&
1448  "Primary vbase should have a zero offset!");
1449 
1450  const ASTRecordLayout &MostDerivedClassLayout =
1451  Context.getASTRecordLayout(MostDerivedClass);
1452 
1453  PrimaryBaseOffset =
1454  MostDerivedClassLayout.getVBaseClassOffset(PrimaryBase);
1455 
1456  const ASTRecordLayout &LayoutClassLayout =
1457  Context.getASTRecordLayout(LayoutClass);
1458 
1459  PrimaryBaseOffsetInLayoutClass =
1460  LayoutClassLayout.getVBaseClassOffset(PrimaryBase);
1461  } else {
1462  assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
1463  "Primary base should have a zero offset!");
1464 
1465  PrimaryBaseOffset = Base.getBaseOffset();
1466  PrimaryBaseOffsetInLayoutClass = BaseOffsetInLayoutClass;
1467  }
1468 
1469  AddMethods(BaseSubobject(PrimaryBase, PrimaryBaseOffset),
1470  PrimaryBaseOffsetInLayoutClass, FirstBaseInPrimaryBaseChain,
1471  FirstBaseOffsetInLayoutClass, PrimaryBases);
1472 
1473  if (!PrimaryBases.insert(PrimaryBase))
1474  llvm_unreachable("Found a duplicate primary base!");
1475  }
1476 
1477  const CXXDestructorDecl *ImplicitVirtualDtor = nullptr;
1478 
1479  typedef llvm::SmallVector<const CXXMethodDecl *, 8> NewVirtualFunctionsTy;
1480  NewVirtualFunctionsTy NewVirtualFunctions;
1481 
1482  // Now go through all virtual member functions and add them.
1483  for (const auto *MD : RD->methods()) {
1484  if (!MD->isVirtual())
1485  continue;
1486  MD = MD->getCanonicalDecl();
1487 
1488  // Get the final overrider.
1489  FinalOverriders::OverriderInfo Overrider =
1490  Overriders.getOverrider(MD, Base.getBaseOffset());
1491 
1492  // Check if this virtual member function overrides a method in a primary
1493  // base. If this is the case, and the return type doesn't require adjustment
1494  // then we can just use the member function from the primary base.
1495  if (const CXXMethodDecl *OverriddenMD =
1496  FindNearestOverriddenMethod(MD, PrimaryBases)) {
1497  if (ComputeReturnAdjustmentBaseOffset(Context, MD,
1498  OverriddenMD).isEmpty()) {
1499  // Replace the method info of the overridden method with our own
1500  // method.
1501  assert(MethodInfoMap.count(OverriddenMD) &&
1502  "Did not find the overridden method!");
1503  MethodInfo &OverriddenMethodInfo = MethodInfoMap[OverriddenMD];
1504 
1505  MethodInfo MethodInfo(Base.getBaseOffset(), BaseOffsetInLayoutClass,
1506  OverriddenMethodInfo.VTableIndex);
1507 
1508  assert(!MethodInfoMap.count(MD) &&
1509  "Should not have method info for this method yet!");
1510 
1511  MethodInfoMap.insert(std::make_pair(MD, MethodInfo));
1512  MethodInfoMap.erase(OverriddenMD);
1513 
1514  // If the overridden method exists in a virtual base class or a direct
1515  // or indirect base class of a virtual base class, we need to emit a
1516  // thunk if we ever have a class hierarchy where the base class is not
1517  // a primary base in the complete object.
1518  if (!isBuildingConstructorVTable() && OverriddenMD != MD) {
1519  // Compute the this adjustment.
1521  ComputeThisAdjustment(OverriddenMD, BaseOffsetInLayoutClass,
1522  Overrider);
1523 
1524  if (ThisAdjustment.Virtual.Itanium.VCallOffsetOffset &&
1525  Overrider.Method->getParent() == MostDerivedClass) {
1526 
1527  // There's no return adjustment from OverriddenMD and MD,
1528  // but that doesn't mean there isn't one between MD and
1529  // the final overrider.
1530  BaseOffset ReturnAdjustmentOffset =
1531  ComputeReturnAdjustmentBaseOffset(Context, Overrider.Method, MD);
1532  ReturnAdjustment ReturnAdjustment =
1533  ComputeReturnAdjustment(ReturnAdjustmentOffset);
1534 
1535  // This is a virtual thunk for the most derived class, add it.
1536  AddThunk(Overrider.Method,
1537  ThunkInfo(ThisAdjustment, ReturnAdjustment));
1538  }
1539  }
1540 
1541  continue;
1542  }
1543  }
1544 
1545  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1546  if (MD->isImplicit()) {
1547  // Itanium C++ ABI 2.5.2:
1548  // If a class has an implicitly-defined virtual destructor,
1549  // its entries come after the declared virtual function pointers.
1550 
1551  assert(!ImplicitVirtualDtor &&
1552  "Did already see an implicit virtual dtor!");
1553  ImplicitVirtualDtor = DD;
1554  continue;
1555  }
1556  }
1557 
1558  NewVirtualFunctions.push_back(MD);
1559  }
1560 
1561  if (ImplicitVirtualDtor)
1562  NewVirtualFunctions.push_back(ImplicitVirtualDtor);
1563 
1564  for (const CXXMethodDecl *MD : NewVirtualFunctions) {
1565  // Get the final overrider.
1566  FinalOverriders::OverriderInfo Overrider =
1567  Overriders.getOverrider(MD, Base.getBaseOffset());
1568 
1569  // Insert the method info for this method.
1570  MethodInfo MethodInfo(Base.getBaseOffset(), BaseOffsetInLayoutClass,
1571  Components.size());
1572 
1573  assert(!MethodInfoMap.count(MD) &&
1574  "Should not have method info for this method yet!");
1575  MethodInfoMap.insert(std::make_pair(MD, MethodInfo));
1576 
1577  // Check if this overrider is going to be used.
1578  const CXXMethodDecl *OverriderMD = Overrider.Method;
1579  if (!IsOverriderUsed(OverriderMD, BaseOffsetInLayoutClass,
1580  FirstBaseInPrimaryBaseChain,
1581  FirstBaseOffsetInLayoutClass)) {
1582  Components.push_back(VTableComponent::MakeUnusedFunction(OverriderMD));
1583  continue;
1584  }
1585 
1586  // Check if this overrider needs a return adjustment.
1587  // We don't want to do this for pure virtual member functions.
1588  BaseOffset ReturnAdjustmentOffset;
1589  if (!OverriderMD->isPure()) {
1590  ReturnAdjustmentOffset =
1591  ComputeReturnAdjustmentBaseOffset(Context, OverriderMD, MD);
1592  }
1593 
1594  ReturnAdjustment ReturnAdjustment =
1595  ComputeReturnAdjustment(ReturnAdjustmentOffset);
1596 
1597  AddMethod(Overrider.Method, ReturnAdjustment);
1598  }
1599 }
1600 
1601 void ItaniumVTableBuilder::LayoutVTable() {
1602  LayoutPrimaryAndSecondaryVTables(BaseSubobject(MostDerivedClass,
1603  CharUnits::Zero()),
1604  /*BaseIsMorallyVirtual=*/false,
1605  MostDerivedClassIsVirtual,
1606  MostDerivedClassOffset);
1607 
1608  VisitedVirtualBasesSetTy VBases;
1609 
1610  // Determine the primary virtual bases.
1611  DeterminePrimaryVirtualBases(MostDerivedClass, MostDerivedClassOffset,
1612  VBases);
1613  VBases.clear();
1614 
1615  LayoutVTablesForVirtualBases(MostDerivedClass, VBases);
1616 
1617  // -fapple-kext adds an extra entry at end of vtbl.
1618  bool IsAppleKext = Context.getLangOpts().AppleKext;
1619  if (IsAppleKext)
1620  Components.push_back(VTableComponent::MakeVCallOffset(CharUnits::Zero()));
1621 }
1622 
1623 void ItaniumVTableBuilder::LayoutPrimaryAndSecondaryVTables(
1624  BaseSubobject Base, bool BaseIsMorallyVirtual,
1625  bool BaseIsVirtualInLayoutClass, CharUnits OffsetInLayoutClass) {
1626  assert(Base.getBase()->isDynamicClass() && "class does not have a vtable!");
1627 
1628  unsigned VTableIndex = Components.size();
1629  VTableIndices.push_back(VTableIndex);
1630 
1631  // Add vcall and vbase offsets for this vtable.
1632  VCallAndVBaseOffsetBuilder Builder(MostDerivedClass, LayoutClass, &Overriders,
1633  Base, BaseIsVirtualInLayoutClass,
1634  OffsetInLayoutClass);
1635  Components.append(Builder.components_begin(), Builder.components_end());
1636 
1637  // Check if we need to add these vcall offsets.
1638  if (BaseIsVirtualInLayoutClass && !Builder.getVCallOffsets().empty()) {
1639  VCallOffsetMap &VCallOffsets = VCallOffsetsForVBases[Base.getBase()];
1640 
1641  if (VCallOffsets.empty())
1642  VCallOffsets = Builder.getVCallOffsets();
1643  }
1644 
1645  // If we're laying out the most derived class we want to keep track of the
1646  // virtual base class offset offsets.
1647  if (Base.getBase() == MostDerivedClass)
1648  VBaseOffsetOffsets = Builder.getVBaseOffsetOffsets();
1649 
1650  // Add the offset to top.
1651  CharUnits OffsetToTop = MostDerivedClassOffset - OffsetInLayoutClass;
1652  Components.push_back(VTableComponent::MakeOffsetToTop(OffsetToTop));
1653 
1654  // Next, add the RTTI.
1655  Components.push_back(VTableComponent::MakeRTTI(MostDerivedClass));
1656 
1657  uint64_t AddressPoint = Components.size();
1658 
1659  // Now go through all virtual member functions and add them.
1660  PrimaryBasesSetVectorTy PrimaryBases;
1661  AddMethods(Base, OffsetInLayoutClass,
1662  Base.getBase(), OffsetInLayoutClass,
1663  PrimaryBases);
1664 
1665  const CXXRecordDecl *RD = Base.getBase();
1666  if (RD == MostDerivedClass) {
1667  assert(MethodVTableIndices.empty());
1668  for (const auto &I : MethodInfoMap) {
1669  const CXXMethodDecl *MD = I.first;
1670  const MethodInfo &MI = I.second;
1671  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1672  MethodVTableIndices[GlobalDecl(DD, Dtor_Complete)]
1673  = MI.VTableIndex - AddressPoint;
1674  MethodVTableIndices[GlobalDecl(DD, Dtor_Deleting)]
1675  = MI.VTableIndex + 1 - AddressPoint;
1676  } else {
1677  MethodVTableIndices[MD] = MI.VTableIndex - AddressPoint;
1678  }
1679  }
1680  }
1681 
1682  // Compute 'this' pointer adjustments.
1683  ComputeThisAdjustments();
1684 
1685  // Add all address points.
1686  while (true) {
1687  AddressPoints.insert(
1688  std::make_pair(BaseSubobject(RD, OffsetInLayoutClass),
1690  unsigned(VTableIndices.size() - 1),
1691  unsigned(AddressPoint - VTableIndex)}));
1692 
1693  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1694  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
1695 
1696  if (!PrimaryBase)
1697  break;
1698 
1699  if (Layout.isPrimaryBaseVirtual()) {
1700  // Check if this virtual primary base is a primary base in the layout
1701  // class. If it's not, we don't want to add it.
1702  const ASTRecordLayout &LayoutClassLayout =
1703  Context.getASTRecordLayout(LayoutClass);
1704 
1705  if (LayoutClassLayout.getVBaseClassOffset(PrimaryBase) !=
1706  OffsetInLayoutClass) {
1707  // We don't want to add this class (or any of its primary bases).
1708  break;
1709  }
1710  }
1711 
1712  RD = PrimaryBase;
1713  }
1714 
1715  // Layout secondary vtables.
1716  LayoutSecondaryVTables(Base, BaseIsMorallyVirtual, OffsetInLayoutClass);
1717 }
1718 
1719 void
1720 ItaniumVTableBuilder::LayoutSecondaryVTables(BaseSubobject Base,
1721  bool BaseIsMorallyVirtual,
1722  CharUnits OffsetInLayoutClass) {
1723  // Itanium C++ ABI 2.5.2:
1724  // Following the primary virtual table of a derived class are secondary
1725  // virtual tables for each of its proper base classes, except any primary
1726  // base(s) with which it shares its primary virtual table.
1727 
1728  const CXXRecordDecl *RD = Base.getBase();
1729  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1730  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
1731 
1732  for (const auto &B : RD->bases()) {
1733  // Ignore virtual bases, we'll emit them later.
1734  if (B.isVirtual())
1735  continue;
1736 
1737  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
1738 
1739  // Ignore bases that don't have a vtable.
1740  if (!BaseDecl->isDynamicClass())
1741  continue;
1742 
1743  if (isBuildingConstructorVTable()) {
1744  // Itanium C++ ABI 2.6.4:
1745  // Some of the base class subobjects may not need construction virtual
1746  // tables, which will therefore not be present in the construction
1747  // virtual table group, even though the subobject virtual tables are
1748  // present in the main virtual table group for the complete object.
1749  if (!BaseIsMorallyVirtual && !BaseDecl->getNumVBases())
1750  continue;
1751  }
1752 
1753  // Get the base offset of this base.
1754  CharUnits RelativeBaseOffset = Layout.getBaseClassOffset(BaseDecl);
1755  CharUnits BaseOffset = Base.getBaseOffset() + RelativeBaseOffset;
1756 
1757  CharUnits BaseOffsetInLayoutClass =
1758  OffsetInLayoutClass + RelativeBaseOffset;
1759 
1760  // Don't emit a secondary vtable for a primary base. We might however want
1761  // to emit secondary vtables for other bases of this base.
1762  if (BaseDecl == PrimaryBase) {
1763  LayoutSecondaryVTables(BaseSubobject(BaseDecl, BaseOffset),
1764  BaseIsMorallyVirtual, BaseOffsetInLayoutClass);
1765  continue;
1766  }
1767 
1768  // Layout the primary vtable (and any secondary vtables) for this base.
1769  LayoutPrimaryAndSecondaryVTables(
1770  BaseSubobject(BaseDecl, BaseOffset),
1771  BaseIsMorallyVirtual,
1772  /*BaseIsVirtualInLayoutClass=*/false,
1773  BaseOffsetInLayoutClass);
1774  }
1775 }
1776 
1777 void ItaniumVTableBuilder::DeterminePrimaryVirtualBases(
1778  const CXXRecordDecl *RD, CharUnits OffsetInLayoutClass,
1779  VisitedVirtualBasesSetTy &VBases) {
1780  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1781 
1782  // Check if this base has a primary base.
1783  if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
1784 
1785  // Check if it's virtual.
1786  if (Layout.isPrimaryBaseVirtual()) {
1787  bool IsPrimaryVirtualBase = true;
1788 
1789  if (isBuildingConstructorVTable()) {
1790  // Check if the base is actually a primary base in the class we use for
1791  // layout.
1792  const ASTRecordLayout &LayoutClassLayout =
1793  Context.getASTRecordLayout(LayoutClass);
1794 
1795  CharUnits PrimaryBaseOffsetInLayoutClass =
1796  LayoutClassLayout.getVBaseClassOffset(PrimaryBase);
1797 
1798  // We know that the base is not a primary base in the layout class if
1799  // the base offsets are different.
1800  if (PrimaryBaseOffsetInLayoutClass != OffsetInLayoutClass)
1801  IsPrimaryVirtualBase = false;
1802  }
1803 
1804  if (IsPrimaryVirtualBase)
1805  PrimaryVirtualBases.insert(PrimaryBase);
1806  }
1807  }
1808 
1809  // Traverse bases, looking for more primary virtual bases.
1810  for (const auto &B : RD->bases()) {
1811  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
1812 
1813  CharUnits BaseOffsetInLayoutClass;
1814 
1815  if (B.isVirtual()) {
1816  if (!VBases.insert(BaseDecl).second)
1817  continue;
1818 
1819  const ASTRecordLayout &LayoutClassLayout =
1820  Context.getASTRecordLayout(LayoutClass);
1821 
1822  BaseOffsetInLayoutClass =
1823  LayoutClassLayout.getVBaseClassOffset(BaseDecl);
1824  } else {
1825  BaseOffsetInLayoutClass =
1826  OffsetInLayoutClass + Layout.getBaseClassOffset(BaseDecl);
1827  }
1828 
1829  DeterminePrimaryVirtualBases(BaseDecl, BaseOffsetInLayoutClass, VBases);
1830  }
1831 }
1832 
1833 void ItaniumVTableBuilder::LayoutVTablesForVirtualBases(
1834  const CXXRecordDecl *RD, VisitedVirtualBasesSetTy &VBases) {
1835  // Itanium C++ ABI 2.5.2:
1836  // Then come the virtual base virtual tables, also in inheritance graph
1837  // order, and again excluding primary bases (which share virtual tables with
1838  // the classes for which they are primary).
1839  for (const auto &B : RD->bases()) {
1840  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
1841 
1842  // Check if this base needs a vtable. (If it's virtual, not a primary base
1843  // of some other class, and we haven't visited it before).
1844  if (B.isVirtual() && BaseDecl->isDynamicClass() &&
1845  !PrimaryVirtualBases.count(BaseDecl) &&
1846  VBases.insert(BaseDecl).second) {
1847  const ASTRecordLayout &MostDerivedClassLayout =
1848  Context.getASTRecordLayout(MostDerivedClass);
1849  CharUnits BaseOffset =
1850  MostDerivedClassLayout.getVBaseClassOffset(BaseDecl);
1851 
1852  const ASTRecordLayout &LayoutClassLayout =
1853  Context.getASTRecordLayout(LayoutClass);
1854  CharUnits BaseOffsetInLayoutClass =
1855  LayoutClassLayout.getVBaseClassOffset(BaseDecl);
1856 
1857  LayoutPrimaryAndSecondaryVTables(
1858  BaseSubobject(BaseDecl, BaseOffset),
1859  /*BaseIsMorallyVirtual=*/true,
1860  /*BaseIsVirtualInLayoutClass=*/true,
1861  BaseOffsetInLayoutClass);
1862  }
1863 
1864  // We only need to check the base for virtual base vtables if it actually
1865  // has virtual bases.
1866  if (BaseDecl->getNumVBases())
1867  LayoutVTablesForVirtualBases(BaseDecl, VBases);
1868  }
1869 }
1870 
1871 /// dumpLayout - Dump the vtable layout.
1872 void ItaniumVTableBuilder::dumpLayout(raw_ostream &Out) {
1873  // FIXME: write more tests that actually use the dumpLayout output to prevent
1874  // ItaniumVTableBuilder regressions.
1875 
1876  if (isBuildingConstructorVTable()) {
1877  Out << "Construction vtable for ('";
1878  MostDerivedClass->printQualifiedName(Out);
1879  Out << "', ";
1880  Out << MostDerivedClassOffset.getQuantity() << ") in '";
1881  LayoutClass->printQualifiedName(Out);
1882  } else {
1883  Out << "Vtable for '";
1884  MostDerivedClass->printQualifiedName(Out);
1885  }
1886  Out << "' (" << Components.size() << " entries).\n";
1887 
1888  // Iterate through the address points and insert them into a new map where
1889  // they are keyed by the index and not the base object.
1890  // Since an address point can be shared by multiple subobjects, we use an
1891  // STL multimap.
1892  std::multimap<uint64_t, BaseSubobject> AddressPointsByIndex;
1893  for (const auto &AP : AddressPoints) {
1894  const BaseSubobject &Base = AP.first;
1895  uint64_t Index =
1896  VTableIndices[AP.second.VTableIndex] + AP.second.AddressPointIndex;
1897 
1898  AddressPointsByIndex.insert(std::make_pair(Index, Base));
1899  }
1900 
1901  for (unsigned I = 0, E = Components.size(); I != E; ++I) {
1902  uint64_t Index = I;
1903 
1904  Out << llvm::format("%4d | ", I);
1905 
1906  const VTableComponent &Component = Components[I];
1907 
1908  // Dump the component.
1909  switch (Component.getKind()) {
1910 
1912  Out << "vcall_offset ("
1913  << Component.getVCallOffset().getQuantity()
1914  << ")";
1915  break;
1916 
1918  Out << "vbase_offset ("
1919  << Component.getVBaseOffset().getQuantity()
1920  << ")";
1921  break;
1922 
1924  Out << "offset_to_top ("
1925  << Component.getOffsetToTop().getQuantity()
1926  << ")";
1927  break;
1928 
1930  Component.getRTTIDecl()->printQualifiedName(Out);
1931  Out << " RTTI";
1932  break;
1933 
1935  const CXXMethodDecl *MD = Component.getFunctionDecl();
1936 
1937  std::string Str =
1939  MD);
1940  Out << Str;
1941  if (MD->isPure())
1942  Out << " [pure]";
1943 
1944  if (MD->isDeleted())
1945  Out << " [deleted]";
1946 
1947  ThunkInfo Thunk = VTableThunks.lookup(I);
1948  if (!Thunk.isEmpty()) {
1949  // If this function pointer has a return adjustment, dump it.
1950  if (!Thunk.Return.isEmpty()) {
1951  Out << "\n [return adjustment: ";
1952  Out << Thunk.Return.NonVirtual << " non-virtual";
1953 
1955  Out << ", " << Thunk.Return.Virtual.Itanium.VBaseOffsetOffset;
1956  Out << " vbase offset offset";
1957  }
1958 
1959  Out << ']';
1960  }
1961 
1962  // If this function pointer has a 'this' pointer adjustment, dump it.
1963  if (!Thunk.This.isEmpty()) {
1964  Out << "\n [this adjustment: ";
1965  Out << Thunk.This.NonVirtual << " non-virtual";
1966 
1967  if (Thunk.This.Virtual.Itanium.VCallOffsetOffset) {
1968  Out << ", " << Thunk.This.Virtual.Itanium.VCallOffsetOffset;
1969  Out << " vcall offset offset";
1970  }
1971 
1972  Out << ']';
1973  }
1974  }
1975 
1976  break;
1977  }
1978 
1981  bool IsComplete =
1983 
1984  const CXXDestructorDecl *DD = Component.getDestructorDecl();
1985 
1986  DD->printQualifiedName(Out);
1987  if (IsComplete)
1988  Out << "() [complete]";
1989  else
1990  Out << "() [deleting]";
1991 
1992  if (DD->isPure())
1993  Out << " [pure]";
1994 
1995  ThunkInfo Thunk = VTableThunks.lookup(I);
1996  if (!Thunk.isEmpty()) {
1997  // If this destructor has a 'this' pointer adjustment, dump it.
1998  if (!Thunk.This.isEmpty()) {
1999  Out << "\n [this adjustment: ";
2000  Out << Thunk.This.NonVirtual << " non-virtual";
2001 
2002  if (Thunk.This.Virtual.Itanium.VCallOffsetOffset) {
2003  Out << ", " << Thunk.This.Virtual.Itanium.VCallOffsetOffset;
2004  Out << " vcall offset offset";
2005  }
2006 
2007  Out << ']';
2008  }
2009  }
2010 
2011  break;
2012  }
2013 
2015  const CXXMethodDecl *MD = Component.getUnusedFunctionDecl();
2016 
2017  std::string Str =
2019  MD);
2020  Out << "[unused] " << Str;
2021  if (MD->isPure())
2022  Out << " [pure]";
2023  }
2024 
2025  }
2026 
2027  Out << '\n';
2028 
2029  // Dump the next address point.
2030  uint64_t NextIndex = Index + 1;
2031  if (AddressPointsByIndex.count(NextIndex)) {
2032  if (AddressPointsByIndex.count(NextIndex) == 1) {
2033  const BaseSubobject &Base =
2034  AddressPointsByIndex.find(NextIndex)->second;
2035 
2036  Out << " -- (";
2037  Base.getBase()->printQualifiedName(Out);
2038  Out << ", " << Base.getBaseOffset().getQuantity();
2039  Out << ") vtable address --\n";
2040  } else {
2041  CharUnits BaseOffset =
2042  AddressPointsByIndex.lower_bound(NextIndex)->second.getBaseOffset();
2043 
2044  // We store the class names in a set to get a stable order.
2045  std::set<std::string> ClassNames;
2046  for (const auto &I :
2047  llvm::make_range(AddressPointsByIndex.equal_range(NextIndex))) {
2048  assert(I.second.getBaseOffset() == BaseOffset &&
2049  "Invalid base offset!");
2050  const CXXRecordDecl *RD = I.second.getBase();
2051  ClassNames.insert(RD->getQualifiedNameAsString());
2052  }
2053 
2054  for (const std::string &Name : ClassNames) {
2055  Out << " -- (" << Name;
2056  Out << ", " << BaseOffset.getQuantity() << ") vtable address --\n";
2057  }
2058  }
2059  }
2060  }
2061 
2062  Out << '\n';
2063 
2064  if (isBuildingConstructorVTable())
2065  return;
2066 
2067  if (MostDerivedClass->getNumVBases()) {
2068  // We store the virtual base class names and their offsets in a map to get
2069  // a stable order.
2070 
2071  std::map<std::string, CharUnits> ClassNamesAndOffsets;
2072  for (const auto &I : VBaseOffsetOffsets) {
2073  std::string ClassName = I.first->getQualifiedNameAsString();
2074  CharUnits OffsetOffset = I.second;
2075  ClassNamesAndOffsets.insert(std::make_pair(ClassName, OffsetOffset));
2076  }
2077 
2078  Out << "Virtual base offset offsets for '";
2079  MostDerivedClass->printQualifiedName(Out);
2080  Out << "' (";
2081  Out << ClassNamesAndOffsets.size();
2082  Out << (ClassNamesAndOffsets.size() == 1 ? " entry" : " entries") << ").\n";
2083 
2084  for (const auto &I : ClassNamesAndOffsets)
2085  Out << " " << I.first << " | " << I.second.getQuantity() << '\n';
2086 
2087  Out << "\n";
2088  }
2089 
2090  if (!Thunks.empty()) {
2091  // We store the method names in a map to get a stable order.
2092  std::map<std::string, const CXXMethodDecl *> MethodNamesAndDecls;
2093 
2094  for (const auto &I : Thunks) {
2095  const CXXMethodDecl *MD = I.first;
2096  std::string MethodName =
2098  MD);
2099 
2100  MethodNamesAndDecls.insert(std::make_pair(MethodName, MD));
2101  }
2102 
2103  for (const auto &I : MethodNamesAndDecls) {
2104  const std::string &MethodName = I.first;
2105  const CXXMethodDecl *MD = I.second;
2106 
2107  ThunkInfoVectorTy ThunksVector = Thunks[MD];
2108  llvm::sort(ThunksVector, [](const ThunkInfo &LHS, const ThunkInfo &RHS) {
2109  assert(LHS.Method == nullptr && RHS.Method == nullptr);
2110  return std::tie(LHS.This, LHS.Return) < std::tie(RHS.This, RHS.Return);
2111  });
2112 
2113  Out << "Thunks for '" << MethodName << "' (" << ThunksVector.size();
2114  Out << (ThunksVector.size() == 1 ? " entry" : " entries") << ").\n";
2115 
2116  for (unsigned I = 0, E = ThunksVector.size(); I != E; ++I) {
2117  const ThunkInfo &Thunk = ThunksVector[I];
2118 
2119  Out << llvm::format("%4d | ", I);
2120 
2121  // If this function pointer has a return pointer adjustment, dump it.
2122  if (!Thunk.Return.isEmpty()) {
2123  Out << "return adjustment: " << Thunk.Return.NonVirtual;
2124  Out << " non-virtual";
2126  Out << ", " << Thunk.Return.Virtual.Itanium.VBaseOffsetOffset;
2127  Out << " vbase offset offset";
2128  }
2129 
2130  if (!Thunk.This.isEmpty())
2131  Out << "\n ";
2132  }
2133 
2134  // If this function pointer has a 'this' pointer adjustment, dump it.
2135  if (!Thunk.This.isEmpty()) {
2136  Out << "this adjustment: ";
2137  Out << Thunk.This.NonVirtual << " non-virtual";
2138 
2139  if (Thunk.This.Virtual.Itanium.VCallOffsetOffset) {
2140  Out << ", " << Thunk.This.Virtual.Itanium.VCallOffsetOffset;
2141  Out << " vcall offset offset";
2142  }
2143  }
2144 
2145  Out << '\n';
2146  }
2147 
2148  Out << '\n';
2149  }
2150  }
2151 
2152  // Compute the vtable indices for all the member functions.
2153  // Store them in a map keyed by the index so we'll get a sorted table.
2154  std::map<uint64_t, std::string> IndicesMap;
2155 
2156  for (const auto *MD : MostDerivedClass->methods()) {
2157  // We only want virtual member functions.
2158  if (!MD->isVirtual())
2159  continue;
2160  MD = MD->getCanonicalDecl();
2161 
2162  std::string MethodName =
2164  MD);
2165 
2166  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
2167  GlobalDecl GD(DD, Dtor_Complete);
2168  assert(MethodVTableIndices.count(GD));
2169  uint64_t VTableIndex = MethodVTableIndices[GD];
2170  IndicesMap[VTableIndex] = MethodName + " [complete]";
2171  IndicesMap[VTableIndex + 1] = MethodName + " [deleting]";
2172  } else {
2173  assert(MethodVTableIndices.count(MD));
2174  IndicesMap[MethodVTableIndices[MD]] = MethodName;
2175  }
2176  }
2177 
2178  // Print the vtable indices for all the member functions.
2179  if (!IndicesMap.empty()) {
2180  Out << "VTable indices for '";
2181  MostDerivedClass->printQualifiedName(Out);
2182  Out << "' (" << IndicesMap.size() << " entries).\n";
2183 
2184  for (const auto &I : IndicesMap) {
2185  uint64_t VTableIndex = I.first;
2186  const std::string &MethodName = I.second;
2187 
2188  Out << llvm::format("%4" PRIu64 " | ", VTableIndex) << MethodName
2189  << '\n';
2190  }
2191  }
2192 
2193  Out << '\n';
2194 }
2195 }
2196 
2198  ArrayRef<VTableComponent> VTableComponents,
2199  ArrayRef<VTableThunkTy> VTableThunks,
2200  const AddressPointsMapTy &AddressPoints)
2201  : VTableComponents(VTableComponents), VTableThunks(VTableThunks),
2202  AddressPoints(AddressPoints) {
2203  if (VTableIndices.size() <= 1)
2204  assert(VTableIndices.size() == 1 && VTableIndices[0] == 0);
2205  else
2206  this->VTableIndices = OwningArrayRef<size_t>(VTableIndices);
2207 
2208  llvm::sort(this->VTableThunks, [](const VTableLayout::VTableThunkTy &LHS,
2209  const VTableLayout::VTableThunkTy &RHS) {
2210  assert((LHS.first != RHS.first || LHS.second == RHS.second) &&
2211  "Different thunks should have unique indices!");
2212  return LHS.first < RHS.first;
2213  });
2214 }
2215 
2217 
2219  : VTableContextBase(/*MS=*/false) {}
2220 
2222 
2224  GD = GD.getCanonicalDecl();
2225  MethodVTableIndicesTy::iterator I = MethodVTableIndices.find(GD);
2226  if (I != MethodVTableIndices.end())
2227  return I->second;
2228 
2229  const CXXRecordDecl *RD = cast<CXXMethodDecl>(GD.getDecl())->getParent();
2230 
2231  computeVTableRelatedInformation(RD);
2232 
2233  I = MethodVTableIndices.find(GD);
2234  assert(I != MethodVTableIndices.end() && "Did not find index!");
2235  return I->second;
2236 }
2237 
2238 CharUnits
2240  const CXXRecordDecl *VBase) {
2241  ClassPairTy ClassPair(RD, VBase);
2242 
2243  VirtualBaseClassOffsetOffsetsMapTy::iterator I =
2244  VirtualBaseClassOffsetOffsets.find(ClassPair);
2245  if (I != VirtualBaseClassOffsetOffsets.end())
2246  return I->second;
2247 
2248  VCallAndVBaseOffsetBuilder Builder(RD, RD, /*FinalOverriders=*/nullptr,
2250  /*BaseIsVirtual=*/false,
2251  /*OffsetInLayoutClass=*/CharUnits::Zero());
2252 
2253  for (const auto &I : Builder.getVBaseOffsetOffsets()) {
2254  // Insert all types.
2255  ClassPairTy ClassPair(RD, I.first);
2256 
2257  VirtualBaseClassOffsetOffsets.insert(std::make_pair(ClassPair, I.second));
2258  }
2259 
2260  I = VirtualBaseClassOffsetOffsets.find(ClassPair);
2261  assert(I != VirtualBaseClassOffsetOffsets.end() && "Did not find index!");
2262 
2263  return I->second;
2264 }
2265 
2266 static std::unique_ptr<VTableLayout>
2267 CreateVTableLayout(const ItaniumVTableBuilder &Builder) {
2269  VTableThunks(Builder.vtable_thunks_begin(), Builder.vtable_thunks_end());
2270 
2271  return llvm::make_unique<VTableLayout>(
2272  Builder.VTableIndices, Builder.vtable_components(), VTableThunks,
2273  Builder.getAddressPoints());
2274 }
2275 
2276 void
2277 ItaniumVTableContext::computeVTableRelatedInformation(const CXXRecordDecl *RD) {
2278  std::unique_ptr<const VTableLayout> &Entry = VTableLayouts[RD];
2279 
2280  // Check if we've computed this information before.
2281  if (Entry)
2282  return;
2283 
2284  ItaniumVTableBuilder Builder(*this, RD, CharUnits::Zero(),
2285  /*MostDerivedClassIsVirtual=*/0, RD);
2286  Entry = CreateVTableLayout(Builder);
2287 
2288  MethodVTableIndices.insert(Builder.vtable_indices_begin(),
2289  Builder.vtable_indices_end());
2290 
2291  // Add the known thunks.
2292  Thunks.insert(Builder.thunks_begin(), Builder.thunks_end());
2293 
2294  // If we don't have the vbase information for this class, insert it.
2295  // getVirtualBaseOffsetOffset will compute it separately without computing
2296  // the rest of the vtable related information.
2297  if (!RD->getNumVBases())
2298  return;
2299 
2300  const CXXRecordDecl *VBase =
2302 
2303  if (VirtualBaseClassOffsetOffsets.count(std::make_pair(RD, VBase)))
2304  return;
2305 
2306  for (const auto &I : Builder.getVBaseOffsetOffsets()) {
2307  // Insert all types.
2308  ClassPairTy ClassPair(RD, I.first);
2309 
2310  VirtualBaseClassOffsetOffsets.insert(std::make_pair(ClassPair, I.second));
2311  }
2312 }
2313 
2314 std::unique_ptr<VTableLayout>
2316  const CXXRecordDecl *MostDerivedClass, CharUnits MostDerivedClassOffset,
2317  bool MostDerivedClassIsVirtual, const CXXRecordDecl *LayoutClass) {
2318  ItaniumVTableBuilder Builder(*this, MostDerivedClass, MostDerivedClassOffset,
2319  MostDerivedClassIsVirtual, LayoutClass);
2320  return CreateVTableLayout(Builder);
2321 }
2322 
2323 namespace {
2324 
2325 // Vtables in the Microsoft ABI are different from the Itanium ABI.
2326 //
2327 // The main differences are:
2328 // 1. Separate vftable and vbtable.
2329 //
2330 // 2. Each subobject with a vfptr gets its own vftable rather than an address
2331 // point in a single vtable shared between all the subobjects.
2332 // Each vftable is represented by a separate section and virtual calls
2333 // must be done using the vftable which has a slot for the function to be
2334 // called.
2335 //
2336 // 3. Virtual method definitions expect their 'this' parameter to point to the
2337 // first vfptr whose table provides a compatible overridden method. In many
2338 // cases, this permits the original vf-table entry to directly call
2339 // the method instead of passing through a thunk.
2340 // See example before VFTableBuilder::ComputeThisOffset below.
2341 //
2342 // A compatible overridden method is one which does not have a non-trivial
2343 // covariant-return adjustment.
2344 //
2345 // The first vfptr is the one with the lowest offset in the complete-object
2346 // layout of the defining class, and the method definition will subtract
2347 // that constant offset from the parameter value to get the real 'this'
2348 // value. Therefore, if the offset isn't really constant (e.g. if a virtual
2349 // function defined in a virtual base is overridden in a more derived
2350 // virtual base and these bases have a reverse order in the complete
2351 // object), the vf-table may require a this-adjustment thunk.
2352 //
2353 // 4. vftables do not contain new entries for overrides that merely require
2354 // this-adjustment. Together with #3, this keeps vf-tables smaller and
2355 // eliminates the need for this-adjustment thunks in many cases, at the cost
2356 // of often requiring redundant work to adjust the "this" pointer.
2357 //
2358 // 5. Instead of VTT and constructor vtables, vbtables and vtordisps are used.
2359 // Vtordisps are emitted into the class layout if a class has
2360 // a) a user-defined ctor/dtor
2361 // and
2362 // b) a method overriding a method in a virtual base.
2363 //
2364 // To get a better understanding of this code,
2365 // you might want to see examples in test/CodeGenCXX/microsoft-abi-vtables-*.cpp
2366 
2367 class VFTableBuilder {
2368 public:
2369  typedef llvm::DenseMap<GlobalDecl, MethodVFTableLocation>
2370  MethodVFTableLocationsTy;
2371 
2372  typedef llvm::iterator_range<MethodVFTableLocationsTy::const_iterator>
2373  method_locations_range;
2374 
2375 private:
2376  /// VTables - Global vtable information.
2377  MicrosoftVTableContext &VTables;
2378 
2379  /// Context - The ASTContext which we will use for layout information.
2380  ASTContext &Context;
2381 
2382  /// MostDerivedClass - The most derived class for which we're building this
2383  /// vtable.
2384  const CXXRecordDecl *MostDerivedClass;
2385 
2386  const ASTRecordLayout &MostDerivedClassLayout;
2387 
2388  const VPtrInfo &WhichVFPtr;
2389 
2390  /// FinalOverriders - The final overriders of the most derived class.
2391  const FinalOverriders Overriders;
2392 
2393  /// Components - The components of the vftable being built.
2395 
2396  MethodVFTableLocationsTy MethodVFTableLocations;
2397 
2398  /// Does this class have an RTTI component?
2399  bool HasRTTIComponent = false;
2400 
2401  /// MethodInfo - Contains information about a method in a vtable.
2402  /// (Used for computing 'this' pointer adjustment thunks.
2403  struct MethodInfo {
2404  /// VBTableIndex - The nonzero index in the vbtable that
2405  /// this method's base has, or zero.
2406  const uint64_t VBTableIndex;
2407 
2408  /// VFTableIndex - The index in the vftable that this method has.
2409  const uint64_t VFTableIndex;
2410 
2411  /// Shadowed - Indicates if this vftable slot is shadowed by
2412  /// a slot for a covariant-return override. If so, it shouldn't be printed
2413  /// or used for vcalls in the most derived class.
2414  bool Shadowed;
2415 
2416  /// UsesExtraSlot - Indicates if this vftable slot was created because
2417  /// any of the overridden slots required a return adjusting thunk.
2418  bool UsesExtraSlot;
2419 
2420  MethodInfo(uint64_t VBTableIndex, uint64_t VFTableIndex,
2421  bool UsesExtraSlot = false)
2422  : VBTableIndex(VBTableIndex), VFTableIndex(VFTableIndex),
2423  Shadowed(false), UsesExtraSlot(UsesExtraSlot) {}
2424 
2425  MethodInfo()
2426  : VBTableIndex(0), VFTableIndex(0), Shadowed(false),
2427  UsesExtraSlot(false) {}
2428  };
2429 
2430  typedef llvm::DenseMap<const CXXMethodDecl *, MethodInfo> MethodInfoMapTy;
2431 
2432  /// MethodInfoMap - The information for all methods in the vftable we're
2433  /// currently building.
2434  MethodInfoMapTy MethodInfoMap;
2435 
2436  typedef llvm::DenseMap<uint64_t, ThunkInfo> VTableThunksMapTy;
2437 
2438  /// VTableThunks - The thunks by vftable index in the vftable currently being
2439  /// built.
2440  VTableThunksMapTy VTableThunks;
2441 
2443  typedef llvm::DenseMap<const CXXMethodDecl *, ThunkInfoVectorTy> ThunksMapTy;
2444 
2445  /// Thunks - A map that contains all the thunks needed for all methods in the
2446  /// most derived class for which the vftable is currently being built.
2447  ThunksMapTy Thunks;
2448 
2449  /// AddThunk - Add a thunk for the given method.
2450  void AddThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk) {
2451  SmallVector<ThunkInfo, 1> &ThunksVector = Thunks[MD];
2452 
2453  // Check if we have this thunk already.
2454  if (std::find(ThunksVector.begin(), ThunksVector.end(), Thunk) !=
2455  ThunksVector.end())
2456  return;
2457 
2458  ThunksVector.push_back(Thunk);
2459  }
2460 
2461  /// ComputeThisOffset - Returns the 'this' argument offset for the given
2462  /// method, relative to the beginning of the MostDerivedClass.
2463  CharUnits ComputeThisOffset(FinalOverriders::OverriderInfo Overrider);
2464 
2465  void CalculateVtordispAdjustment(FinalOverriders::OverriderInfo Overrider,
2466  CharUnits ThisOffset, ThisAdjustment &TA);
2467 
2468  /// AddMethod - Add a single virtual member function to the vftable
2469  /// components vector.
2470  void AddMethod(const CXXMethodDecl *MD, ThunkInfo TI) {
2471  if (!TI.isEmpty()) {
2472  VTableThunks[Components.size()] = TI;
2473  AddThunk(MD, TI);
2474  }
2475  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
2476  assert(TI.Return.isEmpty() &&
2477  "Destructor can't have return adjustment!");
2478  Components.push_back(VTableComponent::MakeDeletingDtor(DD));
2479  } else {
2480  Components.push_back(VTableComponent::MakeFunction(MD));
2481  }
2482  }
2483 
2484  /// AddMethods - Add the methods of this base subobject and the relevant
2485  /// subbases to the vftable we're currently laying out.
2486  void AddMethods(BaseSubobject Base, unsigned BaseDepth,
2487  const CXXRecordDecl *LastVBase,
2488  BasesSetVectorTy &VisitedBases);
2489 
2490  void LayoutVFTable() {
2491  // RTTI data goes before all other entries.
2492  if (HasRTTIComponent)
2493  Components.push_back(VTableComponent::MakeRTTI(MostDerivedClass));
2494 
2495  BasesSetVectorTy VisitedBases;
2496  AddMethods(BaseSubobject(MostDerivedClass, CharUnits::Zero()), 0, nullptr,
2497  VisitedBases);
2498  assert((HasRTTIComponent ? Components.size() - 1 : Components.size()) &&
2499  "vftable can't be empty");
2500 
2501  assert(MethodVFTableLocations.empty());
2502  for (const auto &I : MethodInfoMap) {
2503  const CXXMethodDecl *MD = I.first;
2504  const MethodInfo &MI = I.second;
2505  assert(MD == MD->getCanonicalDecl());
2506 
2507  // Skip the methods that the MostDerivedClass didn't override
2508  // and the entries shadowed by return adjusting thunks.
2509  if (MD->getParent() != MostDerivedClass || MI.Shadowed)
2510  continue;
2511  MethodVFTableLocation Loc(MI.VBTableIndex, WhichVFPtr.getVBaseWithVPtr(),
2512  WhichVFPtr.NonVirtualOffset, MI.VFTableIndex);
2513  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
2514  MethodVFTableLocations[GlobalDecl(DD, Dtor_Deleting)] = Loc;
2515  } else {
2516  MethodVFTableLocations[MD] = Loc;
2517  }
2518  }
2519  }
2520 
2521 public:
2522  VFTableBuilder(MicrosoftVTableContext &VTables,
2523  const CXXRecordDecl *MostDerivedClass, const VPtrInfo &Which)
2524  : VTables(VTables),
2525  Context(MostDerivedClass->getASTContext()),
2526  MostDerivedClass(MostDerivedClass),
2527  MostDerivedClassLayout(Context.getASTRecordLayout(MostDerivedClass)),
2528  WhichVFPtr(Which),
2529  Overriders(MostDerivedClass, CharUnits(), MostDerivedClass) {
2530  // Provide the RTTI component if RTTIData is enabled. If the vftable would
2531  // be available externally, we should not provide the RTTI componenent. It
2532  // is currently impossible to get available externally vftables with either
2533  // dllimport or extern template instantiations, but eventually we may add a
2534  // flag to support additional devirtualization that needs this.
2535  if (Context.getLangOpts().RTTIData)
2536  HasRTTIComponent = true;
2537 
2538  LayoutVFTable();
2539 
2540  if (Context.getLangOpts().DumpVTableLayouts)
2541  dumpLayout(llvm::outs());
2542  }
2543 
2544  uint64_t getNumThunks() const { return Thunks.size(); }
2545 
2546  ThunksMapTy::const_iterator thunks_begin() const { return Thunks.begin(); }
2547 
2548  ThunksMapTy::const_iterator thunks_end() const { return Thunks.end(); }
2549 
2550  method_locations_range vtable_locations() const {
2551  return method_locations_range(MethodVFTableLocations.begin(),
2552  MethodVFTableLocations.end());
2553  }
2554 
2555  ArrayRef<VTableComponent> vtable_components() const { return Components; }
2556 
2557  VTableThunksMapTy::const_iterator vtable_thunks_begin() const {
2558  return VTableThunks.begin();
2559  }
2560 
2561  VTableThunksMapTy::const_iterator vtable_thunks_end() const {
2562  return VTableThunks.end();
2563  }
2564 
2565  void dumpLayout(raw_ostream &);
2566 };
2567 
2568 } // end namespace
2569 
2570 // Let's study one class hierarchy as an example:
2571 // struct A {
2572 // virtual void f();
2573 // int x;
2574 // };
2575 //
2576 // struct B : virtual A {
2577 // virtual void f();
2578 // };
2579 //
2580 // Record layouts:
2581 // struct A:
2582 // 0 | (A vftable pointer)
2583 // 4 | int x
2584 //
2585 // struct B:
2586 // 0 | (B vbtable pointer)
2587 // 4 | struct A (virtual base)
2588 // 4 | (A vftable pointer)
2589 // 8 | int x
2590 //
2591 // Let's assume we have a pointer to the A part of an object of dynamic type B:
2592 // B b;
2593 // A *a = (A*)&b;
2594 // a->f();
2595 //
2596 // In this hierarchy, f() belongs to the vftable of A, so B::f() expects
2597 // "this" parameter to point at the A subobject, which is B+4.
2598 // In the B::f() prologue, it adjusts "this" back to B by subtracting 4,
2599 // performed as a *static* adjustment.
2600 //
2601 // Interesting thing happens when we alter the relative placement of A and B
2602 // subobjects in a class:
2603 // struct C : virtual B { };
2604 //
2605 // C c;
2606 // A *a = (A*)&c;
2607 // a->f();
2608 //
2609 // Respective record layout is:
2610 // 0 | (C vbtable pointer)
2611 // 4 | struct A (virtual base)
2612 // 4 | (A vftable pointer)
2613 // 8 | int x
2614 // 12 | struct B (virtual base)
2615 // 12 | (B vbtable pointer)
2616 //
2617 // The final overrider of f() in class C is still B::f(), so B+4 should be
2618 // passed as "this" to that code. However, "a" points at B-8, so the respective
2619 // vftable entry should hold a thunk that adds 12 to the "this" argument before
2620 // performing a tail call to B::f().
2621 //
2622 // With this example in mind, we can now calculate the 'this' argument offset
2623 // for the given method, relative to the beginning of the MostDerivedClass.
2624 CharUnits
2625 VFTableBuilder::ComputeThisOffset(FinalOverriders::OverriderInfo Overrider) {
2626  BasesSetVectorTy Bases;
2627 
2628  {
2629  // Find the set of least derived bases that define the given method.
2630  OverriddenMethodsSetTy VisitedOverriddenMethods;
2631  auto InitialOverriddenDefinitionCollector = [&](
2632  const CXXMethodDecl *OverriddenMD) {
2633  if (OverriddenMD->size_overridden_methods() == 0)
2634  Bases.insert(OverriddenMD->getParent());
2635  // Don't recurse on this method if we've already collected it.
2636  return VisitedOverriddenMethods.insert(OverriddenMD).second;
2637  };
2638  visitAllOverriddenMethods(Overrider.Method,
2639  InitialOverriddenDefinitionCollector);
2640  }
2641 
2642  // If there are no overrides then 'this' is located
2643  // in the base that defines the method.
2644  if (Bases.size() == 0)
2645  return Overrider.Offset;
2646 
2647  CXXBasePaths Paths;
2648  Overrider.Method->getParent()->lookupInBases(
2649  [&Bases](const CXXBaseSpecifier *Specifier, CXXBasePath &) {
2650  return Bases.count(Specifier->getType()->getAsCXXRecordDecl());
2651  },
2652  Paths);
2653 
2654  // This will hold the smallest this offset among overridees of MD.
2655  // This implies that an offset of a non-virtual base will dominate an offset
2656  // of a virtual base to potentially reduce the number of thunks required
2657  // in the derived classes that inherit this method.
2658  CharUnits Ret;
2659  bool First = true;
2660 
2661  const ASTRecordLayout &OverriderRDLayout =
2662  Context.getASTRecordLayout(Overrider.Method->getParent());
2663  for (const CXXBasePath &Path : Paths) {
2664  CharUnits ThisOffset = Overrider.Offset;
2665  CharUnits LastVBaseOffset;
2666 
2667  // For each path from the overrider to the parents of the overridden
2668  // methods, traverse the path, calculating the this offset in the most
2669  // derived class.
2670  for (const CXXBasePathElement &Element : Path) {
2671  QualType CurTy = Element.Base->getType();
2672  const CXXRecordDecl *PrevRD = Element.Class,
2673  *CurRD = CurTy->getAsCXXRecordDecl();
2674  const ASTRecordLayout &Layout = Context.getASTRecordLayout(PrevRD);
2675 
2676  if (Element.Base->isVirtual()) {
2677  // The interesting things begin when you have virtual inheritance.
2678  // The final overrider will use a static adjustment equal to the offset
2679  // of the vbase in the final overrider class.
2680  // For example, if the final overrider is in a vbase B of the most
2681  // derived class and it overrides a method of the B's own vbase A,
2682  // it uses A* as "this". In its prologue, it can cast A* to B* with
2683  // a static offset. This offset is used regardless of the actual
2684  // offset of A from B in the most derived class, requiring an
2685  // this-adjusting thunk in the vftable if A and B are laid out
2686  // differently in the most derived class.
2687  LastVBaseOffset = ThisOffset =
2688  Overrider.Offset + OverriderRDLayout.getVBaseClassOffset(CurRD);
2689  } else {
2690  ThisOffset += Layout.getBaseClassOffset(CurRD);
2691  }
2692  }
2693 
2694  if (isa<CXXDestructorDecl>(Overrider.Method)) {
2695  if (LastVBaseOffset.isZero()) {
2696  // If a "Base" class has at least one non-virtual base with a virtual
2697  // destructor, the "Base" virtual destructor will take the address
2698  // of the "Base" subobject as the "this" argument.
2699  ThisOffset = Overrider.Offset;
2700  } else {
2701  // A virtual destructor of a virtual base takes the address of the
2702  // virtual base subobject as the "this" argument.
2703  ThisOffset = LastVBaseOffset;
2704  }
2705  }
2706 
2707  if (Ret > ThisOffset || First) {
2708  First = false;
2709  Ret = ThisOffset;
2710  }
2711  }
2712 
2713  assert(!First && "Method not found in the given subobject?");
2714  return Ret;
2715 }
2716 
2717 // Things are getting even more complex when the "this" adjustment has to
2718 // use a dynamic offset instead of a static one, or even two dynamic offsets.
2719 // This is sometimes required when a virtual call happens in the middle of
2720 // a non-most-derived class construction or destruction.
2721 //
2722 // Let's take a look at the following example:
2723 // struct A {
2724 // virtual void f();
2725 // };
2726 //
2727 // void foo(A *a) { a->f(); } // Knows nothing about siblings of A.
2728 //
2729 // struct B : virtual A {
2730 // virtual void f();
2731 // B() {
2732 // foo(this);
2733 // }
2734 // };
2735 //
2736 // struct C : virtual B {
2737 // virtual void f();
2738 // };
2739 //
2740 // Record layouts for these classes are:
2741 // struct A
2742 // 0 | (A vftable pointer)
2743 //
2744 // struct B
2745 // 0 | (B vbtable pointer)
2746 // 4 | (vtordisp for vbase A)
2747 // 8 | struct A (virtual base)
2748 // 8 | (A vftable pointer)
2749 //
2750 // struct C
2751 // 0 | (C vbtable pointer)
2752 // 4 | (vtordisp for vbase A)
2753 // 8 | struct A (virtual base) // A precedes B!
2754 // 8 | (A vftable pointer)
2755 // 12 | struct B (virtual base)
2756 // 12 | (B vbtable pointer)
2757 //
2758 // When one creates an object of type C, the C constructor:
2759 // - initializes all the vbptrs, then
2760 // - calls the A subobject constructor
2761 // (initializes A's vfptr with an address of A vftable), then
2762 // - calls the B subobject constructor
2763 // (initializes A's vfptr with an address of B vftable and vtordisp for A),
2764 // that in turn calls foo(), then
2765 // - initializes A's vfptr with an address of C vftable and zeroes out the
2766 // vtordisp
2767 // FIXME: if a structor knows it belongs to MDC, why doesn't it use a vftable
2768 // without vtordisp thunks?
2769 // FIXME: how are vtordisp handled in the presence of nooverride/final?
2770 //
2771 // When foo() is called, an object with a layout of class C has a vftable
2772 // referencing B::f() that assumes a B layout, so the "this" adjustments are
2773 // incorrect, unless an extra adjustment is done. This adjustment is called
2774 // "vtordisp adjustment". Vtordisp basically holds the difference between the
2775 // actual location of a vbase in the layout class and the location assumed by
2776 // the vftable of the class being constructed/destructed. Vtordisp is only
2777 // needed if "this" escapes a
2778 // structor (or we can't prove otherwise).
2779 // [i.e. vtordisp is a dynamic adjustment for a static adjustment, which is an
2780 // estimation of a dynamic adjustment]
2781 //
2782 // foo() gets a pointer to the A vbase and doesn't know anything about B or C,
2783 // so it just passes that pointer as "this" in a virtual call.
2784 // If there was no vtordisp, that would just dispatch to B::f().
2785 // However, B::f() assumes B+8 is passed as "this",
2786 // yet the pointer foo() passes along is B-4 (i.e. C+8).
2787 // An extra adjustment is needed, so we emit a thunk into the B vftable.
2788 // This vtordisp thunk subtracts the value of vtordisp
2789 // from the "this" argument (-12) before making a tailcall to B::f().
2790 //
2791 // Let's consider an even more complex example:
2792 // struct D : virtual B, virtual C {
2793 // D() {
2794 // foo(this);
2795 // }
2796 // };
2797 //
2798 // struct D
2799 // 0 | (D vbtable pointer)
2800 // 4 | (vtordisp for vbase A)
2801 // 8 | struct A (virtual base) // A precedes both B and C!
2802 // 8 | (A vftable pointer)
2803 // 12 | struct B (virtual base) // B precedes C!
2804 // 12 | (B vbtable pointer)
2805 // 16 | struct C (virtual base)
2806 // 16 | (C vbtable pointer)
2807 //
2808 // When D::D() calls foo(), we find ourselves in a thunk that should tailcall
2809 // to C::f(), which assumes C+8 as its "this" parameter. This time, foo()
2810 // passes along A, which is C-8. The A vtordisp holds
2811 // "D.vbptr[index_of_A] - offset_of_A_in_D"
2812 // and we statically know offset_of_A_in_D, so can get a pointer to D.
2813 // When we know it, we can make an extra vbtable lookup to locate the C vbase
2814 // and one extra static adjustment to calculate the expected value of C+8.
2815 void VFTableBuilder::CalculateVtordispAdjustment(
2816  FinalOverriders::OverriderInfo Overrider, CharUnits ThisOffset,
2817  ThisAdjustment &TA) {
2818  const ASTRecordLayout::VBaseOffsetsMapTy &VBaseMap =
2819  MostDerivedClassLayout.getVBaseOffsetsMap();
2820  const ASTRecordLayout::VBaseOffsetsMapTy::const_iterator &VBaseMapEntry =
2821  VBaseMap.find(WhichVFPtr.getVBaseWithVPtr());
2822  assert(VBaseMapEntry != VBaseMap.end());
2823 
2824  // If there's no vtordisp or the final overrider is defined in the same vbase
2825  // as the initial declaration, we don't need any vtordisp adjustment.
2826  if (!VBaseMapEntry->second.hasVtorDisp() ||
2827  Overrider.VirtualBase == WhichVFPtr.getVBaseWithVPtr())
2828  return;
2829 
2830  // OK, now we know we need to use a vtordisp thunk.
2831  // The implicit vtordisp field is located right before the vbase.
2832  CharUnits OffsetOfVBaseWithVFPtr = VBaseMapEntry->second.VBaseOffset;
2834  (OffsetOfVBaseWithVFPtr - WhichVFPtr.FullOffsetInMDC).getQuantity() - 4;
2835 
2836  // A simple vtordisp thunk will suffice if the final overrider is defined
2837  // in either the most derived class or its non-virtual base.
2838  if (Overrider.Method->getParent() == MostDerivedClass ||
2839  !Overrider.VirtualBase)
2840  return;
2841 
2842  // Otherwise, we need to do use the dynamic offset of the final overrider
2843  // in order to get "this" adjustment right.
2845  (OffsetOfVBaseWithVFPtr + WhichVFPtr.NonVirtualOffset -
2846  MostDerivedClassLayout.getVBPtrOffset()).getQuantity();
2848  Context.getTypeSizeInChars(Context.IntTy).getQuantity() *
2849  VTables.getVBTableIndex(MostDerivedClass, Overrider.VirtualBase);
2850 
2851  TA.NonVirtual = (ThisOffset - Overrider.Offset).getQuantity();
2852 }
2853 
2855  const CXXRecordDecl *RD,
2856  SmallVector<const CXXMethodDecl *, 10> &VirtualMethods) {
2857  // Put the virtual methods into VirtualMethods in the proper order:
2858  // 1) Group overloads by declaration name. New groups are added to the
2859  // vftable in the order of their first declarations in this class
2860  // (including overrides, non-virtual methods and any other named decl that
2861  // might be nested within the class).
2862  // 2) In each group, new overloads appear in the reverse order of declaration.
2863  typedef SmallVector<const CXXMethodDecl *, 1> MethodGroup;
2865  typedef llvm::DenseMap<DeclarationName, unsigned> VisitedGroupIndicesTy;
2866  VisitedGroupIndicesTy VisitedGroupIndices;
2867  for (const auto *D : RD->decls()) {
2868  const auto *ND = dyn_cast<NamedDecl>(D);
2869  if (!ND)
2870  continue;
2871  VisitedGroupIndicesTy::iterator J;
2872  bool Inserted;
2873  std::tie(J, Inserted) = VisitedGroupIndices.insert(
2874  std::make_pair(ND->getDeclName(), Groups.size()));
2875  if (Inserted)
2876  Groups.push_back(MethodGroup());
2877  if (const auto *MD = dyn_cast<CXXMethodDecl>(ND))
2878  if (MD->isVirtual())
2879  Groups[J->second].push_back(MD->getCanonicalDecl());
2880  }
2881 
2882  for (const MethodGroup &Group : Groups)
2883  VirtualMethods.append(Group.rbegin(), Group.rend());
2884 }
2885 
2886 static bool isDirectVBase(const CXXRecordDecl *Base, const CXXRecordDecl *RD) {
2887  for (const auto &B : RD->bases()) {
2888  if (B.isVirtual() && B.getType()->getAsCXXRecordDecl() == Base)
2889  return true;
2890  }
2891  return false;
2892 }
2893 
2894 void VFTableBuilder::AddMethods(BaseSubobject Base, unsigned BaseDepth,
2895  const CXXRecordDecl *LastVBase,
2896  BasesSetVectorTy &VisitedBases) {
2897  const CXXRecordDecl *RD = Base.getBase();
2898  if (!RD->isPolymorphic())
2899  return;
2900 
2901  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
2902 
2903  // See if this class expands a vftable of the base we look at, which is either
2904  // the one defined by the vfptr base path or the primary base of the current
2905  // class.
2906  const CXXRecordDecl *NextBase = nullptr, *NextLastVBase = LastVBase;
2907  CharUnits NextBaseOffset;
2908  if (BaseDepth < WhichVFPtr.PathToIntroducingObject.size()) {
2909  NextBase = WhichVFPtr.PathToIntroducingObject[BaseDepth];
2910  if (isDirectVBase(NextBase, RD)) {
2911  NextLastVBase = NextBase;
2912  NextBaseOffset = MostDerivedClassLayout.getVBaseClassOffset(NextBase);
2913  } else {
2914  NextBaseOffset =
2915  Base.getBaseOffset() + Layout.getBaseClassOffset(NextBase);
2916  }
2917  } else if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
2918  assert(!Layout.isPrimaryBaseVirtual() &&
2919  "No primary virtual bases in this ABI");
2920  NextBase = PrimaryBase;
2921  NextBaseOffset = Base.getBaseOffset();
2922  }
2923 
2924  if (NextBase) {
2925  AddMethods(BaseSubobject(NextBase, NextBaseOffset), BaseDepth + 1,
2926  NextLastVBase, VisitedBases);
2927  if (!VisitedBases.insert(NextBase))
2928  llvm_unreachable("Found a duplicate primary base!");
2929  }
2930 
2932  // Put virtual methods in the proper order.
2933  GroupNewVirtualOverloads(RD, VirtualMethods);
2934 
2935  // Now go through all virtual member functions and add them to the current
2936  // vftable. This is done by
2937  // - replacing overridden methods in their existing slots, as long as they
2938  // don't require return adjustment; calculating This adjustment if needed.
2939  // - adding new slots for methods of the current base not present in any
2940  // sub-bases;
2941  // - adding new slots for methods that require Return adjustment.
2942  // We keep track of the methods visited in the sub-bases in MethodInfoMap.
2943  for (const CXXMethodDecl *MD : VirtualMethods) {
2944  FinalOverriders::OverriderInfo FinalOverrider =
2945  Overriders.getOverrider(MD, Base.getBaseOffset());
2946  const CXXMethodDecl *FinalOverriderMD = FinalOverrider.Method;
2947  const CXXMethodDecl *OverriddenMD =
2948  FindNearestOverriddenMethod(MD, VisitedBases);
2949 
2950  ThisAdjustment ThisAdjustmentOffset;
2951  bool ReturnAdjustingThunk = false, ForceReturnAdjustmentMangling = false;
2952  CharUnits ThisOffset = ComputeThisOffset(FinalOverrider);
2953  ThisAdjustmentOffset.NonVirtual =
2954  (ThisOffset - WhichVFPtr.FullOffsetInMDC).getQuantity();
2955  if ((OverriddenMD || FinalOverriderMD != MD) &&
2956  WhichVFPtr.getVBaseWithVPtr())
2957  CalculateVtordispAdjustment(FinalOverrider, ThisOffset,
2958  ThisAdjustmentOffset);
2959 
2960  unsigned VBIndex =
2961  LastVBase ? VTables.getVBTableIndex(MostDerivedClass, LastVBase) : 0;
2962 
2963  if (OverriddenMD) {
2964  // If MD overrides anything in this vftable, we need to update the
2965  // entries.
2966  MethodInfoMapTy::iterator OverriddenMDIterator =
2967  MethodInfoMap.find(OverriddenMD);
2968 
2969  // If the overridden method went to a different vftable, skip it.
2970  if (OverriddenMDIterator == MethodInfoMap.end())
2971  continue;
2972 
2973  MethodInfo &OverriddenMethodInfo = OverriddenMDIterator->second;
2974 
2975  VBIndex = OverriddenMethodInfo.VBTableIndex;
2976 
2977  // Let's check if the overrider requires any return adjustments.
2978  // We must create a new slot if the MD's return type is not trivially
2979  // convertible to the OverriddenMD's one.
2980  // Once a chain of method overrides adds a return adjusting vftable slot,
2981  // all subsequent overrides will also use an extra method slot.
2982  ReturnAdjustingThunk = !ComputeReturnAdjustmentBaseOffset(
2983  Context, MD, OverriddenMD).isEmpty() ||
2984  OverriddenMethodInfo.UsesExtraSlot;
2985 
2986  if (!ReturnAdjustingThunk) {
2987  // No return adjustment needed - just replace the overridden method info
2988  // with the current info.
2989  MethodInfo MI(VBIndex, OverriddenMethodInfo.VFTableIndex);
2990  MethodInfoMap.erase(OverriddenMDIterator);
2991 
2992  assert(!MethodInfoMap.count(MD) &&
2993  "Should not have method info for this method yet!");
2994  MethodInfoMap.insert(std::make_pair(MD, MI));
2995  continue;
2996  }
2997 
2998  // In case we need a return adjustment, we'll add a new slot for
2999  // the overrider. Mark the overridden method as shadowed by the new slot.
3000  OverriddenMethodInfo.Shadowed = true;
3001 
3002  // Force a special name mangling for a return-adjusting thunk
3003  // unless the method is the final overrider without this adjustment.
3004  ForceReturnAdjustmentMangling =
3005  !(MD == FinalOverriderMD && ThisAdjustmentOffset.isEmpty());
3006  } else if (Base.getBaseOffset() != WhichVFPtr.FullOffsetInMDC ||
3007  MD->size_overridden_methods()) {
3008  // Skip methods that don't belong to the vftable of the current class,
3009  // e.g. each method that wasn't seen in any of the visited sub-bases
3010  // but overrides multiple methods of other sub-bases.
3011  continue;
3012  }
3013 
3014  // If we got here, MD is a method not seen in any of the sub-bases or
3015  // it requires return adjustment. Insert the method info for this method.
3016  MethodInfo MI(VBIndex,
3017  HasRTTIComponent ? Components.size() - 1 : Components.size(),
3018  ReturnAdjustingThunk);
3019 
3020  assert(!MethodInfoMap.count(MD) &&
3021  "Should not have method info for this method yet!");
3022  MethodInfoMap.insert(std::make_pair(MD, MI));
3023 
3024  // Check if this overrider needs a return adjustment.
3025  // We don't want to do this for pure virtual member functions.
3026  BaseOffset ReturnAdjustmentOffset;
3028  if (!FinalOverriderMD->isPure()) {
3029  ReturnAdjustmentOffset =
3030  ComputeReturnAdjustmentBaseOffset(Context, FinalOverriderMD, MD);
3031  }
3032  if (!ReturnAdjustmentOffset.isEmpty()) {
3033  ForceReturnAdjustmentMangling = true;
3034  ReturnAdjustment.NonVirtual =
3035  ReturnAdjustmentOffset.NonVirtualOffset.getQuantity();
3036  if (ReturnAdjustmentOffset.VirtualBase) {
3037  const ASTRecordLayout &DerivedLayout =
3038  Context.getASTRecordLayout(ReturnAdjustmentOffset.DerivedClass);
3039  ReturnAdjustment.Virtual.Microsoft.VBPtrOffset =
3040  DerivedLayout.getVBPtrOffset().getQuantity();
3041  ReturnAdjustment.Virtual.Microsoft.VBIndex =
3042  VTables.getVBTableIndex(ReturnAdjustmentOffset.DerivedClass,
3043  ReturnAdjustmentOffset.VirtualBase);
3044  }
3045  }
3046 
3047  AddMethod(FinalOverriderMD,
3048  ThunkInfo(ThisAdjustmentOffset, ReturnAdjustment,
3049  ForceReturnAdjustmentMangling ? MD : nullptr));
3050  }
3051 }
3052 
3053 static void PrintBasePath(const VPtrInfo::BasePath &Path, raw_ostream &Out) {
3054  for (const CXXRecordDecl *Elem :
3055  llvm::make_range(Path.rbegin(), Path.rend())) {
3056  Out << "'";
3057  Elem->printQualifiedName(Out);
3058  Out << "' in ";
3059  }
3060 }
3061 
3062 static void dumpMicrosoftThunkAdjustment(const ThunkInfo &TI, raw_ostream &Out,
3063  bool ContinueFirstLine) {
3064  const ReturnAdjustment &R = TI.Return;
3065  bool Multiline = false;
3066  const char *LinePrefix = "\n ";
3067  if (!R.isEmpty() || TI.Method) {
3068  if (!ContinueFirstLine)
3069  Out << LinePrefix;
3070  Out << "[return adjustment (to type '"
3072  << "'): ";
3074  Out << "vbptr at offset " << R.Virtual.Microsoft.VBPtrOffset << ", ";
3075  if (R.Virtual.Microsoft.VBIndex)
3076  Out << "vbase #" << R.Virtual.Microsoft.VBIndex << ", ";
3077  Out << R.NonVirtual << " non-virtual]";
3078  Multiline = true;
3079  }
3080 
3081  const ThisAdjustment &T = TI.This;
3082  if (!T.isEmpty()) {
3083  if (Multiline || !ContinueFirstLine)
3084  Out << LinePrefix;
3085  Out << "[this adjustment: ";
3086  if (!TI.This.Virtual.isEmpty()) {
3087  assert(T.Virtual.Microsoft.VtordispOffset < 0);
3088  Out << "vtordisp at " << T.Virtual.Microsoft.VtordispOffset << ", ";
3089  if (T.Virtual.Microsoft.VBPtrOffset) {
3090  Out << "vbptr at " << T.Virtual.Microsoft.VBPtrOffset
3091  << " to the left,";
3092  assert(T.Virtual.Microsoft.VBOffsetOffset > 0);
3093  Out << LinePrefix << " vboffset at "
3094  << T.Virtual.Microsoft.VBOffsetOffset << " in the vbtable, ";
3095  }
3096  }
3097  Out << T.NonVirtual << " non-virtual]";
3098  }
3099 }
3100 
3101 void VFTableBuilder::dumpLayout(raw_ostream &Out) {
3102  Out << "VFTable for ";
3103  PrintBasePath(WhichVFPtr.PathToIntroducingObject, Out);
3104  Out << "'";
3105  MostDerivedClass->printQualifiedName(Out);
3106  Out << "' (" << Components.size()
3107  << (Components.size() == 1 ? " entry" : " entries") << ").\n";
3108 
3109  for (unsigned I = 0, E = Components.size(); I != E; ++I) {
3110  Out << llvm::format("%4d | ", I);
3111 
3112  const VTableComponent &Component = Components[I];
3113 
3114  // Dump the component.
3115  switch (Component.getKind()) {
3117  Component.getRTTIDecl()->printQualifiedName(Out);
3118  Out << " RTTI";
3119  break;
3120 
3122  const CXXMethodDecl *MD = Component.getFunctionDecl();
3123 
3124  // FIXME: Figure out how to print the real thunk type, since they can
3125  // differ in the return type.
3126  std::string Str = PredefinedExpr::ComputeName(
3128  Out << Str;
3129  if (MD->isPure())
3130  Out << " [pure]";
3131 
3132  if (MD->isDeleted())
3133  Out << " [deleted]";
3134 
3135  ThunkInfo Thunk = VTableThunks.lookup(I);
3136  if (!Thunk.isEmpty())
3137  dumpMicrosoftThunkAdjustment(Thunk, Out, /*ContinueFirstLine=*/false);
3138 
3139  break;
3140  }
3141 
3143  const CXXDestructorDecl *DD = Component.getDestructorDecl();
3144 
3145  DD->printQualifiedName(Out);
3146  Out << "() [scalar deleting]";
3147 
3148  if (DD->isPure())
3149  Out << " [pure]";
3150 
3151  ThunkInfo Thunk = VTableThunks.lookup(I);
3152  if (!Thunk.isEmpty()) {
3153  assert(Thunk.Return.isEmpty() &&
3154  "No return adjustment needed for destructors!");
3155  dumpMicrosoftThunkAdjustment(Thunk, Out, /*ContinueFirstLine=*/false);
3156  }
3157 
3158  break;
3159  }
3160 
3161  default:
3162  DiagnosticsEngine &Diags = Context.getDiagnostics();
3163  unsigned DiagID = Diags.getCustomDiagID(
3165  "Unexpected vftable component type %0 for component number %1");
3166  Diags.Report(MostDerivedClass->getLocation(), DiagID)
3167  << I << Component.getKind();
3168  }
3169 
3170  Out << '\n';
3171  }
3172 
3173  Out << '\n';
3174 
3175  if (!Thunks.empty()) {
3176  // We store the method names in a map to get a stable order.
3177  std::map<std::string, const CXXMethodDecl *> MethodNamesAndDecls;
3178 
3179  for (const auto &I : Thunks) {
3180  const CXXMethodDecl *MD = I.first;
3181  std::string MethodName = PredefinedExpr::ComputeName(
3183 
3184  MethodNamesAndDecls.insert(std::make_pair(MethodName, MD));
3185  }
3186 
3187  for (const auto &MethodNameAndDecl : MethodNamesAndDecls) {
3188  const std::string &MethodName = MethodNameAndDecl.first;
3189  const CXXMethodDecl *MD = MethodNameAndDecl.second;
3190 
3191  ThunkInfoVectorTy ThunksVector = Thunks[MD];
3192  std::stable_sort(ThunksVector.begin(), ThunksVector.end(),
3193  [](const ThunkInfo &LHS, const ThunkInfo &RHS) {
3194  // Keep different thunks with the same adjustments in the order they
3195  // were put into the vector.
3196  return std::tie(LHS.This, LHS.Return) < std::tie(RHS.This, RHS.Return);
3197  });
3198 
3199  Out << "Thunks for '" << MethodName << "' (" << ThunksVector.size();
3200  Out << (ThunksVector.size() == 1 ? " entry" : " entries") << ").\n";
3201 
3202  for (unsigned I = 0, E = ThunksVector.size(); I != E; ++I) {
3203  const ThunkInfo &Thunk = ThunksVector[I];
3204 
3205  Out << llvm::format("%4d | ", I);
3206  dumpMicrosoftThunkAdjustment(Thunk, Out, /*ContinueFirstLine=*/true);
3207  Out << '\n';
3208  }
3209 
3210  Out << '\n';
3211  }
3212  }
3213 
3214  Out.flush();
3215 }
3216 
3217 static bool setsIntersect(const llvm::SmallPtrSet<const CXXRecordDecl *, 4> &A,
3219  for (const CXXRecordDecl *Decl : B) {
3220  if (A.count(Decl))
3221  return true;
3222  }
3223  return false;
3224 }
3225 
3226 static bool rebucketPaths(VPtrInfoVector &Paths);
3227 
3228 /// Produces MSVC-compatible vbtable data. The symbols produced by this
3229 /// algorithm match those produced by MSVC 2012 and newer, which is different
3230 /// from MSVC 2010.
3231 ///
3232 /// MSVC 2012 appears to minimize the vbtable names using the following
3233 /// algorithm. First, walk the class hierarchy in the usual order, depth first,
3234 /// left to right, to find all of the subobjects which contain a vbptr field.
3235 /// Visiting each class node yields a list of inheritance paths to vbptrs. Each
3236 /// record with a vbptr creates an initially empty path.
3237 ///
3238 /// To combine paths from child nodes, the paths are compared to check for
3239 /// ambiguity. Paths are "ambiguous" if multiple paths have the same set of
3240 /// components in the same order. Each group of ambiguous paths is extended by
3241 /// appending the class of the base from which it came. If the current class
3242 /// node produced an ambiguous path, its path is extended with the current class.
3243 /// After extending paths, MSVC again checks for ambiguity, and extends any
3244 /// ambiguous path which wasn't already extended. Because each node yields an
3245 /// unambiguous set of paths, MSVC doesn't need to extend any path more than once
3246 /// to produce an unambiguous set of paths.
3247 ///
3248 /// TODO: Presumably vftables use the same algorithm.
3249 void MicrosoftVTableContext::computeVTablePaths(bool ForVBTables,
3250  const CXXRecordDecl *RD,
3251  VPtrInfoVector &Paths) {
3252  assert(Paths.empty());
3253  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3254 
3255  // Base case: this subobject has its own vptr.
3256  if (ForVBTables ? Layout.hasOwnVBPtr() : Layout.hasOwnVFPtr())
3257  Paths.push_back(llvm::make_unique<VPtrInfo>(RD));
3258 
3259  // Recursive case: get all the vbtables from our bases and remove anything
3260  // that shares a virtual base.
3261  llvm::SmallPtrSet<const CXXRecordDecl*, 4> VBasesSeen;
3262  for (const auto &B : RD->bases()) {
3263  const CXXRecordDecl *Base = B.getType()->getAsCXXRecordDecl();
3264  if (B.isVirtual() && VBasesSeen.count(Base))
3265  continue;
3266 
3267  if (!Base->isDynamicClass())
3268  continue;
3269 
3270  const VPtrInfoVector &BasePaths =
3271  ForVBTables ? enumerateVBTables(Base) : getVFPtrOffsets(Base);
3272 
3273  for (const std::unique_ptr<VPtrInfo> &BaseInfo : BasePaths) {
3274  // Don't include the path if it goes through a virtual base that we've
3275  // already included.
3276  if (setsIntersect(VBasesSeen, BaseInfo->ContainingVBases))
3277  continue;
3278 
3279  // Copy the path and adjust it as necessary.
3280  auto P = llvm::make_unique<VPtrInfo>(*BaseInfo);
3281 
3282  // We mangle Base into the path if the path would've been ambiguous and it
3283  // wasn't already extended with Base.
3284  if (P->MangledPath.empty() || P->MangledPath.back() != Base)
3285  P->NextBaseToMangle = Base;
3286 
3287  // Keep track of which vtable the derived class is going to extend with
3288  // new methods or bases. We append to either the vftable of our primary
3289  // base, or the first non-virtual base that has a vbtable.
3290  if (P->ObjectWithVPtr == Base &&
3291  Base == (ForVBTables ? Layout.getBaseSharingVBPtr()
3292  : Layout.getPrimaryBase()))
3293  P->ObjectWithVPtr = RD;
3294 
3295  // Keep track of the full adjustment from the MDC to this vtable. The
3296  // adjustment is captured by an optional vbase and a non-virtual offset.
3297  if (B.isVirtual())
3298  P->ContainingVBases.push_back(Base);
3299  else if (P->ContainingVBases.empty())
3300  P->NonVirtualOffset += Layout.getBaseClassOffset(Base);
3301 
3302  // Update the full offset in the MDC.
3303  P->FullOffsetInMDC = P->NonVirtualOffset;
3304  if (const CXXRecordDecl *VB = P->getVBaseWithVPtr())
3305  P->FullOffsetInMDC += Layout.getVBaseClassOffset(VB);
3306 
3307  Paths.push_back(std::move(P));
3308  }
3309 
3310  if (B.isVirtual())
3311  VBasesSeen.insert(Base);
3312 
3313  // After visiting any direct base, we've transitively visited all of its
3314  // morally virtual bases.
3315  for (const auto &VB : Base->vbases())
3316  VBasesSeen.insert(VB.getType()->getAsCXXRecordDecl());
3317  }
3318 
3319  // Sort the paths into buckets, and if any of them are ambiguous, extend all
3320  // paths in ambiguous buckets.
3321  bool Changed = true;
3322  while (Changed)
3323  Changed = rebucketPaths(Paths);
3324 }
3325 
3326 static bool extendPath(VPtrInfo &P) {
3327  if (P.NextBaseToMangle) {
3328  P.MangledPath.push_back(P.NextBaseToMangle);
3329  P.NextBaseToMangle = nullptr;// Prevent the path from being extended twice.
3330  return true;
3331  }
3332  return false;
3333 }
3334 
3335 static bool rebucketPaths(VPtrInfoVector &Paths) {
3336  // What we're essentially doing here is bucketing together ambiguous paths.
3337  // Any bucket with more than one path in it gets extended by NextBase, which
3338  // is usually the direct base of the inherited the vbptr. This code uses a
3339  // sorted vector to implement a multiset to form the buckets. Note that the
3340  // ordering is based on pointers, but it doesn't change our output order. The
3341  // current algorithm is designed to match MSVC 2012's names.
3343  PathsSorted.reserve(Paths.size());
3344  for (auto& P : Paths)
3345  PathsSorted.push_back(*P);
3346  llvm::sort(PathsSorted, [](const VPtrInfo &LHS, const VPtrInfo &RHS) {
3347  return LHS.MangledPath < RHS.MangledPath;
3348  });
3349  bool Changed = false;
3350  for (size_t I = 0, E = PathsSorted.size(); I != E;) {
3351  // Scan forward to find the end of the bucket.
3352  size_t BucketStart = I;
3353  do {
3354  ++I;
3355  } while (I != E &&
3356  PathsSorted[BucketStart].get().MangledPath ==
3357  PathsSorted[I].get().MangledPath);
3358 
3359  // If this bucket has multiple paths, extend them all.
3360  if (I - BucketStart > 1) {
3361  for (size_t II = BucketStart; II != I; ++II)
3362  Changed |= extendPath(PathsSorted[II]);
3363  assert(Changed && "no paths were extended to fix ambiguity");
3364  }
3365  }
3366  return Changed;
3367 }
3368 
3370 
3371 namespace {
3372 typedef llvm::SetVector<BaseSubobject, std::vector<BaseSubobject>,
3373  llvm::DenseSet<BaseSubobject>> FullPathTy;
3374 }
3375 
3376 // This recursive function finds all paths from a subobject centered at
3377 // (RD, Offset) to the subobject located at IntroducingObject.
3378 static void findPathsToSubobject(ASTContext &Context,
3379  const ASTRecordLayout &MostDerivedLayout,
3380  const CXXRecordDecl *RD, CharUnits Offset,
3381  BaseSubobject IntroducingObject,
3382  FullPathTy &FullPath,
3383  std::list<FullPathTy> &Paths) {
3384  if (BaseSubobject(RD, Offset) == IntroducingObject) {
3385  Paths.push_back(FullPath);
3386  return;
3387  }
3388 
3389  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3390 
3391  for (const CXXBaseSpecifier &BS : RD->bases()) {
3392  const CXXRecordDecl *Base = BS.getType()->getAsCXXRecordDecl();
3393  CharUnits NewOffset = BS.isVirtual()
3394  ? MostDerivedLayout.getVBaseClassOffset(Base)
3395  : Offset + Layout.getBaseClassOffset(Base);
3396  FullPath.insert(BaseSubobject(Base, NewOffset));
3397  findPathsToSubobject(Context, MostDerivedLayout, Base, NewOffset,
3398  IntroducingObject, FullPath, Paths);
3399  FullPath.pop_back();
3400  }
3401 }
3402 
3403 // Return the paths which are not subsets of other paths.
3404 static void removeRedundantPaths(std::list<FullPathTy> &FullPaths) {
3405  FullPaths.remove_if([&](const FullPathTy &SpecificPath) {
3406  for (const FullPathTy &OtherPath : FullPaths) {
3407  if (&SpecificPath == &OtherPath)
3408  continue;
3409  if (llvm::all_of(SpecificPath, [&](const BaseSubobject &BSO) {
3410  return OtherPath.count(BSO) != 0;
3411  })) {
3412  return true;
3413  }
3414  }
3415  return false;
3416  });
3417 }
3418 
3420  const CXXRecordDecl *RD,
3421  const FullPathTy &FullPath) {
3422  const ASTRecordLayout &MostDerivedLayout =
3423  Context.getASTRecordLayout(RD);
3425  for (const BaseSubobject &BSO : FullPath) {
3426  const CXXRecordDecl *Base = BSO.getBase();
3427  // The first entry in the path is always the most derived record, skip it.
3428  if (Base == RD) {
3429  assert(Offset.getQuantity() == -1);
3430  Offset = CharUnits::Zero();
3431  continue;
3432  }
3433  assert(Offset.getQuantity() != -1);
3434  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3435  // While we know which base has to be traversed, we don't know if that base
3436  // was a virtual base.
3437  const CXXBaseSpecifier *BaseBS = std::find_if(
3438  RD->bases_begin(), RD->bases_end(), [&](const CXXBaseSpecifier &BS) {
3439  return BS.getType()->getAsCXXRecordDecl() == Base;
3440  });
3441  Offset = BaseBS->isVirtual() ? MostDerivedLayout.getVBaseClassOffset(Base)
3442  : Offset + Layout.getBaseClassOffset(Base);
3443  RD = Base;
3444  }
3445  return Offset;
3446 }
3447 
3448 // We want to select the path which introduces the most covariant overrides. If
3449 // two paths introduce overrides which the other path doesn't contain, issue a
3450 // diagnostic.
3451 static const FullPathTy *selectBestPath(ASTContext &Context,
3452  const CXXRecordDecl *RD,
3453  const VPtrInfo &Info,
3454  std::list<FullPathTy> &FullPaths) {
3455  // Handle some easy cases first.
3456  if (FullPaths.empty())
3457  return nullptr;
3458  if (FullPaths.size() == 1)
3459  return &FullPaths.front();
3460 
3461  const FullPathTy *BestPath = nullptr;
3462  typedef std::set<const CXXMethodDecl *> OverriderSetTy;
3463  OverriderSetTy LastOverrides;
3464  for (const FullPathTy &SpecificPath : FullPaths) {
3465  assert(!SpecificPath.empty());
3466  OverriderSetTy CurrentOverrides;
3467  const CXXRecordDecl *TopLevelRD = SpecificPath.begin()->getBase();
3468  // Find the distance from the start of the path to the subobject with the
3469  // VPtr.
3470  CharUnits BaseOffset =
3471  getOffsetOfFullPath(Context, TopLevelRD, SpecificPath);
3472  FinalOverriders Overriders(TopLevelRD, CharUnits::Zero(), TopLevelRD);
3473  for (const CXXMethodDecl *MD : Info.IntroducingObject->methods()) {
3474  if (!MD->isVirtual())
3475  continue;
3476  FinalOverriders::OverriderInfo OI =
3477  Overriders.getOverrider(MD->getCanonicalDecl(), BaseOffset);
3478  const CXXMethodDecl *OverridingMethod = OI.Method;
3479  // Only overriders which have a return adjustment introduce problematic
3480  // thunks.
3481  if (ComputeReturnAdjustmentBaseOffset(Context, OverridingMethod, MD)
3482  .isEmpty())
3483  continue;
3484  // It's possible that the overrider isn't in this path. If so, skip it
3485  // because this path didn't introduce it.
3486  const CXXRecordDecl *OverridingParent = OverridingMethod->getParent();
3487  if (llvm::none_of(SpecificPath, [&](const BaseSubobject &BSO) {
3488  return BSO.getBase() == OverridingParent;
3489  }))
3490  continue;
3491  CurrentOverrides.insert(OverridingMethod);
3492  }
3493  OverriderSetTy NewOverrides =
3494  llvm::set_difference(CurrentOverrides, LastOverrides);
3495  if (NewOverrides.empty())
3496  continue;
3497  OverriderSetTy MissingOverrides =
3498  llvm::set_difference(LastOverrides, CurrentOverrides);
3499  if (MissingOverrides.empty()) {
3500  // This path is a strict improvement over the last path, let's use it.
3501  BestPath = &SpecificPath;
3502  std::swap(CurrentOverrides, LastOverrides);
3503  } else {
3504  // This path introduces an overrider with a conflicting covariant thunk.
3505  DiagnosticsEngine &Diags = Context.getDiagnostics();
3506  const CXXMethodDecl *CovariantMD = *NewOverrides.begin();
3507  const CXXMethodDecl *ConflictMD = *MissingOverrides.begin();
3508  Diags.Report(RD->getLocation(), diag::err_vftable_ambiguous_component)
3509  << RD;
3510  Diags.Report(CovariantMD->getLocation(), diag::note_covariant_thunk)
3511  << CovariantMD;
3512  Diags.Report(ConflictMD->getLocation(), diag::note_covariant_thunk)
3513  << ConflictMD;
3514  }
3515  }
3516  // Go with the path that introduced the most covariant overrides. If there is
3517  // no such path, pick the first path.
3518  return BestPath ? BestPath : &FullPaths.front();
3519 }
3520 
3522  const CXXRecordDecl *RD,
3523  VPtrInfoVector &Paths) {
3524  const ASTRecordLayout &MostDerivedLayout = Context.getASTRecordLayout(RD);
3525  FullPathTy FullPath;
3526  std::list<FullPathTy> FullPaths;
3527  for (const std::unique_ptr<VPtrInfo>& Info : Paths) {
3529  Context, MostDerivedLayout, RD, CharUnits::Zero(),
3530  BaseSubobject(Info->IntroducingObject, Info->FullOffsetInMDC), FullPath,
3531  FullPaths);
3532  FullPath.clear();
3533  removeRedundantPaths(FullPaths);
3534  Info->PathToIntroducingObject.clear();
3535  if (const FullPathTy *BestPath =
3536  selectBestPath(Context, RD, *Info, FullPaths))
3537  for (const BaseSubobject &BSO : *BestPath)
3538  Info->PathToIntroducingObject.push_back(BSO.getBase());
3539  FullPaths.clear();
3540  }
3541 }
3542 
3543 static bool vfptrIsEarlierInMDC(const ASTRecordLayout &Layout,
3544  const MethodVFTableLocation &LHS,
3545  const MethodVFTableLocation &RHS) {
3546  CharUnits L = LHS.VFPtrOffset;
3547  CharUnits R = RHS.VFPtrOffset;
3548  if (LHS.VBase)
3549  L += Layout.getVBaseClassOffset(LHS.VBase);
3550  if (RHS.VBase)
3551  R += Layout.getVBaseClassOffset(RHS.VBase);
3552  return L < R;
3553 }
3554 
3555 void MicrosoftVTableContext::computeVTableRelatedInformation(
3556  const CXXRecordDecl *RD) {
3557  assert(RD->isDynamicClass());
3558 
3559  // Check if we've computed this information before.
3560  if (VFPtrLocations.count(RD))
3561  return;
3562 
3563  const VTableLayout::AddressPointsMapTy EmptyAddressPointsMap;
3564 
3565  {
3566  auto VFPtrs = llvm::make_unique<VPtrInfoVector>();
3567  computeVTablePaths(/*ForVBTables=*/false, RD, *VFPtrs);
3568  computeFullPathsForVFTables(Context, RD, *VFPtrs);
3569  VFPtrLocations[RD] = std::move(VFPtrs);
3570  }
3571 
3572  MethodVFTableLocationsTy NewMethodLocations;
3573  for (const std::unique_ptr<VPtrInfo> &VFPtr : *VFPtrLocations[RD]) {
3574  VFTableBuilder Builder(*this, RD, *VFPtr);
3575 
3576  VFTableIdTy id(RD, VFPtr->FullOffsetInMDC);
3577  assert(VFTableLayouts.count(id) == 0);
3579  Builder.vtable_thunks_begin(), Builder.vtable_thunks_end());
3580  VFTableLayouts[id] = llvm::make_unique<VTableLayout>(
3581  ArrayRef<size_t>{0}, Builder.vtable_components(), VTableThunks,
3582  EmptyAddressPointsMap);
3583  Thunks.insert(Builder.thunks_begin(), Builder.thunks_end());
3584 
3585  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3586  for (const auto &Loc : Builder.vtable_locations()) {
3587  auto Insert = NewMethodLocations.insert(Loc);
3588  if (!Insert.second) {
3589  const MethodVFTableLocation &NewLoc = Loc.second;
3590  MethodVFTableLocation &OldLoc = Insert.first->second;
3591  if (vfptrIsEarlierInMDC(Layout, NewLoc, OldLoc))
3592  OldLoc = NewLoc;
3593  }
3594  }
3595  }
3596 
3597  MethodVFTableLocations.insert(NewMethodLocations.begin(),
3598  NewMethodLocations.end());
3599  if (Context.getLangOpts().DumpVTableLayouts)
3600  dumpMethodLocations(RD, NewMethodLocations, llvm::outs());
3601 }
3602 
3603 void MicrosoftVTableContext::dumpMethodLocations(
3604  const CXXRecordDecl *RD, const MethodVFTableLocationsTy &NewMethods,
3605  raw_ostream &Out) {
3606  // Compute the vtable indices for all the member functions.
3607  // Store them in a map keyed by the location so we'll get a sorted table.
3608  std::map<MethodVFTableLocation, std::string> IndicesMap;
3609  bool HasNonzeroOffset = false;
3610 
3611  for (const auto &I : NewMethods) {
3612  const CXXMethodDecl *MD = cast<const CXXMethodDecl>(I.first.getDecl());
3613  assert(MD->isVirtual());
3614 
3615  std::string MethodName = PredefinedExpr::ComputeName(
3617 
3618  if (isa<CXXDestructorDecl>(MD)) {
3619  IndicesMap[I.second] = MethodName + " [scalar deleting]";
3620  } else {
3621  IndicesMap[I.second] = MethodName;
3622  }
3623 
3624  if (!I.second.VFPtrOffset.isZero() || I.second.VBTableIndex != 0)
3625  HasNonzeroOffset = true;
3626  }
3627 
3628  // Print the vtable indices for all the member functions.
3629  if (!IndicesMap.empty()) {
3630  Out << "VFTable indices for ";
3631  Out << "'";
3632  RD->printQualifiedName(Out);
3633  Out << "' (" << IndicesMap.size()
3634  << (IndicesMap.size() == 1 ? " entry" : " entries") << ").\n";
3635 
3636  CharUnits LastVFPtrOffset = CharUnits::fromQuantity(-1);
3637  uint64_t LastVBIndex = 0;
3638  for (const auto &I : IndicesMap) {
3639  CharUnits VFPtrOffset = I.first.VFPtrOffset;
3640  uint64_t VBIndex = I.first.VBTableIndex;
3641  if (HasNonzeroOffset &&
3642  (VFPtrOffset != LastVFPtrOffset || VBIndex != LastVBIndex)) {
3643  assert(VBIndex > LastVBIndex || VFPtrOffset > LastVFPtrOffset);
3644  Out << " -- accessible via ";
3645  if (VBIndex)
3646  Out << "vbtable index " << VBIndex << ", ";
3647  Out << "vfptr at offset " << VFPtrOffset.getQuantity() << " --\n";
3648  LastVFPtrOffset = VFPtrOffset;
3649  LastVBIndex = VBIndex;
3650  }
3651 
3652  uint64_t VTableIndex = I.first.Index;
3653  const std::string &MethodName = I.second;
3654  Out << llvm::format("%4" PRIu64 " | ", VTableIndex) << MethodName << '\n';
3655  }
3656  Out << '\n';
3657  }
3658 
3659  Out.flush();
3660 }
3661 
3662 const VirtualBaseInfo &MicrosoftVTableContext::computeVBTableRelatedInformation(
3663  const CXXRecordDecl *RD) {
3664  VirtualBaseInfo *VBI;
3665 
3666  {
3667  // Get or create a VBI for RD. Don't hold a reference to the DenseMap cell,
3668  // as it may be modified and rehashed under us.
3669  std::unique_ptr<VirtualBaseInfo> &Entry = VBaseInfo[RD];
3670  if (Entry)
3671  return *Entry;
3672  Entry = llvm::make_unique<VirtualBaseInfo>();
3673  VBI = Entry.get();
3674  }
3675 
3676  computeVTablePaths(/*ForVBTables=*/true, RD, VBI->VBPtrPaths);
3677 
3678  // First, see if the Derived class shared the vbptr with a non-virtual base.
3679  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3680  if (const CXXRecordDecl *VBPtrBase = Layout.getBaseSharingVBPtr()) {
3681  // If the Derived class shares the vbptr with a non-virtual base, the shared
3682  // virtual bases come first so that the layout is the same.
3683  const VirtualBaseInfo &BaseInfo =
3684  computeVBTableRelatedInformation(VBPtrBase);
3685  VBI->VBTableIndices.insert(BaseInfo.VBTableIndices.begin(),
3686  BaseInfo.VBTableIndices.end());
3687  }
3688 
3689  // New vbases are added to the end of the vbtable.
3690  // Skip the self entry and vbases visited in the non-virtual base, if any.
3691  unsigned VBTableIndex = 1 + VBI->VBTableIndices.size();
3692  for (const auto &VB : RD->vbases()) {
3693  const CXXRecordDecl *CurVBase = VB.getType()->getAsCXXRecordDecl();
3694  if (!VBI->VBTableIndices.count(CurVBase))
3695  VBI->VBTableIndices[CurVBase] = VBTableIndex++;
3696  }
3697 
3698  return *VBI;
3699 }
3700 
3702  const CXXRecordDecl *VBase) {
3703  const VirtualBaseInfo &VBInfo = computeVBTableRelatedInformation(Derived);
3704  assert(VBInfo.VBTableIndices.count(VBase));
3705  return VBInfo.VBTableIndices.find(VBase)->second;
3706 }
3707 
3708 const VPtrInfoVector &
3710  return computeVBTableRelatedInformation(RD).VBPtrPaths;
3711 }
3712 
3713 const VPtrInfoVector &
3715  computeVTableRelatedInformation(RD);
3716 
3717  assert(VFPtrLocations.count(RD) && "Couldn't find vfptr locations");
3718  return *VFPtrLocations[RD];
3719 }
3720 
3721 const VTableLayout &
3723  CharUnits VFPtrOffset) {
3724  computeVTableRelatedInformation(RD);
3725 
3726  VFTableIdTy id(RD, VFPtrOffset);
3727  assert(VFTableLayouts.count(id) && "Couldn't find a VFTable at this offset");
3728  return *VFTableLayouts[id];
3729 }
3730 
3733  assert(cast<CXXMethodDecl>(GD.getDecl())->isVirtual() &&
3734  "Only use this method for virtual methods or dtors");
3735  if (isa<CXXDestructorDecl>(GD.getDecl()))
3736  assert(GD.getDtorType() == Dtor_Deleting);
3737 
3738  GD = GD.getCanonicalDecl();
3739 
3740  MethodVFTableLocationsTy::iterator I = MethodVFTableLocations.find(GD);
3741  if (I != MethodVFTableLocations.end())
3742  return I->second;
3743 
3744  const CXXRecordDecl *RD = cast<CXXMethodDecl>(GD.getDecl())->getParent();
3745 
3746  computeVTableRelatedInformation(RD);
3747 
3748  I = MethodVFTableLocations.find(GD);
3749  assert(I != MethodVFTableLocations.end() && "Did not find index!");
3750  return I->second;
3751 }
Defines the clang::ASTContext interface.
if(T->getSizeExpr()) TRY_TO(TraverseStmt(T -> getSizeExpr()))
PointerType - C99 6.7.5.1 - Pointer Declarators.
Definition: Type.h:2543
bool isPrimaryBaseVirtual() const
isPrimaryBaseVirtual - Get whether the primary base for this record is virtual or not...
Definition: RecordLayout.h:226
A (possibly-)qualified type.
Definition: Type.h:642
base_class_range bases()
Definition: DeclCXX.h:823
uint32_t VBPtrOffset
The offset (in bytes) of the vbptr, relative to the beginning of the derived class.
Definition: ABI.h:61
bool isEmpty() const
Definition: ABI.h:155
CXXDtorType getDtorType() const
Definition: GlobalDecl.h:76
ItaniumVTableContext(ASTContext &Context)
static VTableComponent MakeRTTI(const CXXRecordDecl *RD)
Definition: VTableBuilder.h:67
const CXXMethodDecl * getFunctionDecl() const
const ASTRecordLayout & getASTRecordLayout(const RecordDecl *D) const
Get or compute information about the layout of the specified record (struct/union/class) D...
FunctionType - C99 6.7.5.3 - Function Declarators.
Definition: Type.h:3361
CharUnits getBaseClassOffset(const CXXRecordDecl *Base) const
getBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:233
unsigned getNumVBases() const
Retrieves the number of virtual base classes of this class.
Definition: DeclCXX.h:838
VPtrInfoVector VBPtrPaths
Information on all virtual base tables used when this record is the most derived class.
bool isEmpty() const
Definition: ABI.h:87
Decl - This represents one declaration (or definition), e.g.
Definition: DeclBase.h:87
CharUnits VFPtrOffset
This is the offset of the vfptr from the start of the last vbase, or the complete type if there are n...
bool isVirtual() const
Definition: DeclCXX.h:2086
bool isVirtual() const
Determines whether the base class is a virtual base class (or not).
Definition: DeclCXX.h:245
StringRef P
GlobalDecl getCanonicalDecl() const
Definition: GlobalDecl.h:60
int64_t NonVirtual
The non-virtual adjustment from the derived object to its nearest virtual base.
Definition: ABI.h:111
CanQual< T > getUnqualifiedType() const
Retrieve the unqualified form of this type.
DiagnosticsEngine & getDiagnostics() const
bool isDerivedFrom(const CXXRecordDecl *Base) const
Determine whether this class is derived from the class Base.
DiagnosticBuilder Report(SourceLocation Loc, unsigned DiagID)
Issue the message to the client.
Definition: Diagnostic.h:1292
bool isZero() const
isZero - Test whether the quantity equals zero.
Definition: CharUnits.h:116
const TargetInfo & getTargetInfo() const
Definition: ASTContext.h:689
const NestedNameSpecifier * Specifier
BasePath MangledPath
The bases from the inheritance path that got used to mangle the vbtable name.
Represents a path from a specific derived class (which is not represented as part of the path) to a p...
static std::unique_ptr< VTableLayout > CreateVTableLayout(const ItaniumVTableBuilder &Builder)
static VTableComponent MakeUnusedFunction(const CXXMethodDecl *MD)
Definition: VTableBuilder.h:89
const CXXMethodDecl * getUnusedFunctionDecl() const
QualType getReturnType() const
Definition: Decl.h:2303
const CXXRecordDecl * VBase
If nonnull, holds the last vbase which contains the vfptr that the method definition is adjusted to...
const T * getAs() const
Member-template getAs<specific type>&#39;.
Definition: Type.h:6716
decl_range decls() const
decls_begin/decls_end - Iterate over the declarations stored in this context.
Definition: DeclBase.h:1997
static VTableComponent MakeVCallOffset(CharUnits Offset)
Definition: VTableBuilder.h:55
A this pointer adjustment.
Definition: ABI.h:108
const CXXMethodDecl * Method
Holds a pointer to the overridden method this thunk is for, if needed by the ABI to distinguish diffe...
Definition: ABI.h:191
CharUnits getBaseOffset() const
getBaseOffset - Returns the base class offset.
Definition: BaseSubobject.h:46
uint64_t getPointerWidth(unsigned AddrSpace) const
Return the width of pointers on this target, for the specified address space.
Definition: TargetInfo.h:348
int32_t VBOffsetOffset
The offset (in bytes) of the vbase offset in the vbtable.
Definition: ABI.h:132
DeclarationName getDeclName() const
Get the actual, stored name of the declaration, which may be a special name.
Definition: Decl.h:297
TargetCXXABI getCXXABI() const
Get the C++ ABI currently in use.
Definition: TargetInfo.h:1018
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:154
ArrayRef< QualType > getParamTypes() const
Definition: Type.h:3886
CXXMethodDecl * getCanonicalDecl() override
Retrieves the "canonical" declaration of the given declaration.
Definition: DeclCXX.h:2127
static VTableComponent MakeCompleteDtor(const CXXDestructorDecl *DD)
Definition: VTableBuilder.h:79
A return adjustment.
Definition: ABI.h:42
static CharUnits Zero()
Zero - Construct a CharUnits quantity of zero.
Definition: CharUnits.h:53
llvm::DenseMap< const CXXRecordDecl *, unsigned > VBTableIndices
A map from virtual base to vbtable index for doing a conversion from the the derived class to the a b...
CharUnits getVBaseClassOffset(const CXXRecordDecl *VBase) const
getVBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:241
The this pointer adjustment as well as an optional return adjustment for a thunk. ...
Definition: ABI.h:179
const CXXRecordDecl * NextBaseToMangle
The next base to push onto the mangled path if this path is ambiguous in a derived class...
unsigned getTypeQuals() const
Definition: Type.h:4006
struct clang::ThisAdjustment::VirtualAdjustment::@132 Microsoft
The set of methods that override a given virtual method in each subobject where it occurs...
CharUnits - This is an opaque type for sizes expressed in character units.
Definition: CharUnits.h:38
llvm::DenseMap< const CXXMethodDecl *, ThunkInfoVectorTy > ThunksMapTy
static void dump(llvm::raw_ostream &OS, StringRef FunctionName, ArrayRef< CounterExpression > Expressions, ArrayRef< CounterMappingRegion > Regions)
const CXXRecordDecl * IntroducingObject
This is the class that introduced the vptr by declaring new virtual methods or virtual bases...
Deleting dtor.
Definition: ABI.h:35
Concrete class used by the front-end to report problems and issues.
Definition: Diagnostic.h:149
const VPtrInfoVector & getVFPtrOffsets(const CXXRecordDecl *RD)
struct clang::ThisAdjustment::VirtualAdjustment::@131 Itanium
base_class_iterator bases_begin()
Definition: DeclCXX.h:830
static void removeRedundantPaths(std::list< FullPathTy > &FullPaths)
uint64_t getMethodVTableIndex(GlobalDecl GD)
Locate a virtual function in the vtable.
CharUnits getVirtualBaseOffsetOffset(const CXXRecordDecl *RD, const CXXRecordDecl *VBase)
Return the offset in chars (relative to the vtable address point) where the offset of the virtual bas...
static bool setsIntersect(const llvm::SmallPtrSet< const CXXRecordDecl *, 4 > &A, ArrayRef< const CXXRecordDecl *> B)
static VTableComponent MakeDeletingDtor(const CXXDestructorDecl *DD)
Definition: VTableBuilder.h:84
CXXRecordDecl * getAsCXXRecordDecl() const
Retrieves the CXXRecordDecl that this type refers to, either because the type is a RecordType or beca...
Definition: Type.cpp:1613
Represents a prototype with parameter type info, e.g.
Definition: Type.h:3686
bool isDynamicClass() const
Definition: DeclCXX.h:789
union clang::ReturnAdjustment::VirtualAdjustment Virtual
QuantityType getQuantity() const
getQuantity - Get the raw integer representation of this quantity.
Definition: CharUnits.h:179
unsigned Offset
Definition: Format.cpp:1631
ASTRecordLayout - This class contains layout information for one RecordDecl, which is a struct/union/...
Definition: RecordLayout.h:39
struct clang::ReturnAdjustment::VirtualAdjustment::@129 Itanium
static void GroupNewVirtualOverloads(const CXXRecordDecl *RD, SmallVector< const CXXMethodDecl *, 10 > &VirtualMethods)
SmallVector< ThunkInfo, 1 > ThunkInfoVectorTy
Kind getKind() const
Get the kind of this vtable component.
Definition: VTableBuilder.h:97
void getFinalOverriders(CXXFinalOverriderMap &FinaOverriders) const
Retrieve the final overriders for each virtual member function in the class hierarchy where this clas...
Represents a C++ destructor within a class.
Definition: DeclCXX.h:2703
bool isImplicit() const
isImplicit - Indicates whether the declaration was implicitly generated by the implementation.
Definition: DeclBase.h:547
overridden_method_range overridden_methods() const
Definition: DeclCXX.cpp:2170
CharUnits getOffsetToTop() const
CharUnits getVCallOffset() const
const CXXRecordDecl * getPrimaryBase() const
getPrimaryBase - Get the primary base for this record.
Definition: RecordLayout.h:218
static CharUnits fromQuantity(QuantityType Quantity)
fromQuantity - Construct a CharUnits quantity from a raw integer type.
Definition: CharUnits.h:63
internal::Matcher< T > id(StringRef ID, const internal::BindableMatcher< T > &InnerMatcher)
If the provided matcher matches a node, binds the node to ID.
Definition: ASTMatchers.h:137
static void findPathsToSubobject(ASTContext &Context, const ASTRecordLayout &MostDerivedLayout, const CXXRecordDecl *RD, CharUnits Offset, BaseSubobject IntroducingObject, FullPathTy &FullPath, std::list< FullPathTy > &Paths)
const CXXRecordDecl * getBase() const
getBase - Returns the base class declaration.
Definition: BaseSubobject.h:43
bool isPolymorphic() const
Whether this class is polymorphic (C++ [class.virtual]), which means that the class contains or inher...
Definition: DeclCXX.h:1337
DeclContext * getParent()
getParent - Returns the containing DeclContext.
Definition: DeclBase.h:1752
const CXXDestructorDecl * getDestructorDecl() const
struct clang::ReturnAdjustment::VirtualAdjustment::@130 Microsoft
Uniquely identifies a virtual method within a class hierarchy by the method itself and a class subobj...
CharUnits getVBPtrOffset() const
getVBPtrOffset - Get the offset for virtual base table pointer.
Definition: RecordLayout.h:306
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:1527
GlobalDecl - represents a global declaration.
Definition: GlobalDecl.h:35
static void PrintBasePath(const VPtrInfo::BasePath &Path, raw_ostream &Out)
int64_t NonVirtual
The non-virtual adjustment from the derived object to its nearest virtual base.
Definition: ABI.h:45
unsigned getVBTableIndex(const CXXRecordDecl *Derived, const CXXRecordDecl *VBase)
Returns the index of VBase in the vbtable of Derived.
const CXXBaseSpecifier * Base
The base specifier that states the link from a derived class to a base class, which will be followed ...
#define false
Definition: stdbool.h:33
QualType getCanonicalType() const
Definition: Type.h:6097
static bool rebucketPaths(VPtrInfoVector &Paths)
std::unique_ptr< VTableLayout > createConstructionVTableLayout(const CXXRecordDecl *MostDerivedClass, CharUnits MostDerivedClassOffset, bool MostDerivedClassIsVirtual, const CXXRecordDecl *LayoutClass)
QualType getReturnType() const
Definition: Type.h:3617
bool isPure() const
Whether this virtual function is pure, i.e.
Definition: Decl.h:2010
static void dumpMicrosoftThunkAdjustment(const ThunkInfo &TI, raw_ostream &Out, bool ContinueFirstLine)
ASTContext & getASTContext() const LLVM_READONLY
Definition: DeclBase.cpp:376
static bool vfptrIsEarlierInMDC(const ASTRecordLayout &Layout, const MethodVFTableLocation &LHS, const MethodVFTableLocation &RHS)
const Decl * getDecl() const
Definition: GlobalDecl.h:69
Represents a single component in a vtable.
Definition: VTableBuilder.h:30
Represents a static or instance method of a struct/union/class.
Definition: DeclCXX.h:2041
static std::string ComputeName(IdentKind IK, const Decl *CurrentDecl)
Definition: Expr.cpp:523
const VTableLayout & getVFTableLayout(const CXXRecordDecl *RD, CharUnits VFPtrOffset)
The same as PrettyFunction, except that the &#39;virtual&#39; keyword is omitted for virtual member functions...
Definition: Expr.h:1790
unsigned getCustomDiagID(Level L, const char(&FormatString)[N])
Return an ID for a diagnostic with the specified format string and level.
Definition: Diagnostic.h:773
int64_t VCallOffsetOffset
The offset (in bytes), relative to the address point, of the virtual call offset. ...
Definition: ABI.h:120
Complete object dtor.
Definition: ABI.h:36
const CXXRecordDecl * getRTTIDecl() const
CanProxy< U > getAs() const
Retrieve a canonical type pointer with a different static type, upcasting or downcasting as needed...
static VTableComponent MakeVBaseOffset(CharUnits Offset)
Definition: VTableBuilder.h:59
Represents an element in a path from a derived class to a base class.
Dataflow Directional Tag Classes.
ThisAdjustment This
The this pointer adjustment.
Definition: ABI.h:181
const VPtrInfoVector & enumerateVBTables(const CXXRecordDecl *RD)
static bool isDirectVBase(const CXXRecordDecl *Base, const CXXRecordDecl *RD)
ThunksMapTy Thunks
Contains all thunks that a given method decl will need.
static bool extendPath(VPtrInfo &P)
The name of a declaration.
static std::string getAsString(SplitQualType split, const PrintingPolicy &Policy)
Definition: Type.h:975
const CXXRecordDecl * getParent() const
Returns the parent of this method declaration, which is the class in which this method is defined...
Definition: DeclCXX.h:2166
const CXXRecordDecl * getBaseSharingVBPtr() const
Definition: RecordLayout.h:311
A mapping from each virtual member function to its set of final overriders.
static CharUnits getOffsetOfFullPath(ASTContext &Context, const CXXRecordDecl *RD, const FullPathTy &FullPath)
int64_t VBaseOffsetOffset
The offset (in bytes), relative to the address point of the virtual base class offset.
Definition: ABI.h:54
CharUnits NonVirtualOffset
IntroducingObject is at this offset from its containing complete object or virtual base...
base_class_iterator vbases_begin()
Definition: DeclCXX.h:847
bool isEmpty() const
Definition: ABI.h:204
All virtual base related information about a given record decl.
union clang::ThisAdjustment::VirtualAdjustment Virtual
VTableLayout(ArrayRef< size_t > VTableIndices, ArrayRef< VTableComponent > VTableComponents, ArrayRef< VTableThunkTy > VTableThunks, const AddressPointsMapTy &AddressPoints)
const CXXRecordDecl * getVBaseWithVPtr() const
The vptr is stored inside the non-virtual component of this virtual base.
CXXBasePath & front()
static const FullPathTy * selectBestPath(ASTContext &Context, const CXXRecordDecl *RD, const VPtrInfo &Info, std::list< FullPathTy > &FullPaths)
Base for LValueReferenceType and RValueReferenceType.
Definition: Type.h:2679
ReturnAdjustment Return
The return adjustment.
Definition: ABI.h:184
Represents a base class of a C++ class.
Definition: DeclCXX.h:192
CanQualType getCanonicalType(QualType T) const
Return the canonical (structural) type corresponding to the specified potentially non-canonical type ...
Definition: ASTContext.h:2252
CharUnits toCharUnitsFromBits(int64_t BitSize) const
Convert a size in bits to a size in characters.
llvm::DenseMap< BaseSubobject, AddressPointLocation > AddressPointsMapTy
Represents a C++ struct/union/class.
Definition: DeclCXX.h:300
int32_t VtordispOffset
The offset of the vtordisp (in bytes), relative to the ECX.
Definition: ABI.h:125
base_class_iterator bases_end()
Definition: DeclCXX.h:832
std::pair< uint64_t, ThunkInfo > VTableThunkTy
llvm::DenseMap< const CXXRecordDecl *, VBaseInfo > VBaseOffsetsMapTy
Definition: RecordLayout.h:60
Defines the clang::TargetInfo interface.
bool isMicrosoft() const
Is this ABI an MSVC-compatible ABI?
Definition: TargetCXXABI.h:154
A pointer to the deleting destructor.
Definition: VTableBuilder.h:43
static Decl::Kind getKind(const Decl *D)
Definition: DeclBase.cpp:954
CanQualType IntTy
Definition: ASTContext.h:1024
MethodVFTableLocation getMethodVFTableLocation(GlobalDecl GD)
static VTableComponent MakeFunction(const CXXMethodDecl *MD)
Definition: VTableBuilder.h:71
bool isDeleted() const
Whether this function has been deleted.
Definition: Decl.h:2137
Holds information about the inheritance path to a virtual base or function table pointer.
BasePaths - Represents the set of paths from a derived class to one of its (direct or indirect) bases...
CharUnits getTypeSizeInChars(QualType T) const
Return the size of the specified (complete) type T, in characters.
QualType getType() const
Definition: Decl.h:647
uint32_t VBIndex
Index of the virtual base in the vbtable.
Definition: ABI.h:64
This represents a decl that may have a name.
Definition: Decl.h:248
CharUnits getVBaseOffset() const
static void computeFullPathsForVFTables(ASTContext &Context, const CXXRecordDecl *RD, VPtrInfoVector &Paths)
const CXXRecordDecl * Class
The record decl of the class that the base is a base of.
int32_t VBPtrOffset
The offset of the vbptr of the derived class (in bytes), relative to the ECX after vtordisp adjustmen...
Definition: ABI.h:129
const LangOptions & getLangOpts() const
Definition: ASTContext.h:706
base_class_range vbases()
Definition: DeclCXX.h:840
A pointer to the complete destructor.
Definition: VTableBuilder.h:40
SourceLocation getLocation() const
Definition: DeclBase.h:418
method_range methods() const
Definition: DeclCXX.h:865
QualType getType() const
Retrieves the type of the base class.
Definition: DeclCXX.h:291
static VTableComponent MakeOffsetToTop(CharUnits Offset)
Definition: VTableBuilder.h:63