clang  11.0.0git
VTableBuilder.cpp
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1 //===--- VTableBuilder.cpp - C++ vtable layout builder --------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This contains code dealing with generation of the layout of virtual tables.
10 //
11 //===----------------------------------------------------------------------===//
12 
14 #include "clang/AST/ASTContext.h"
17 #include "clang/AST/RecordLayout.h"
18 #include "clang/Basic/TargetInfo.h"
19 #include "llvm/ADT/SetOperations.h"
20 #include "llvm/ADT/SmallPtrSet.h"
21 #include "llvm/Support/Format.h"
22 #include "llvm/Support/raw_ostream.h"
23 #include <algorithm>
24 #include <cstdio>
25 
26 using namespace clang;
27 
28 #define DUMP_OVERRIDERS 0
29 
30 namespace {
31 
32 /// BaseOffset - Represents an offset from a derived class to a direct or
33 /// indirect base class.
34 struct BaseOffset {
35  /// DerivedClass - The derived class.
36  const CXXRecordDecl *DerivedClass;
37 
38  /// VirtualBase - If the path from the derived class to the base class
39  /// involves virtual base classes, this holds the declaration of the last
40  /// virtual base in this path (i.e. closest to the base class).
41  const CXXRecordDecl *VirtualBase;
42 
43  /// NonVirtualOffset - The offset from the derived class to the base class.
44  /// (Or the offset from the virtual base class to the base class, if the
45  /// path from the derived class to the base class involves a virtual base
46  /// class.
47  CharUnits NonVirtualOffset;
48 
49  BaseOffset() : DerivedClass(nullptr), VirtualBase(nullptr),
50  NonVirtualOffset(CharUnits::Zero()) { }
51  BaseOffset(const CXXRecordDecl *DerivedClass,
52  const CXXRecordDecl *VirtualBase, CharUnits NonVirtualOffset)
53  : DerivedClass(DerivedClass), VirtualBase(VirtualBase),
54  NonVirtualOffset(NonVirtualOffset) { }
55 
56  bool isEmpty() const { return NonVirtualOffset.isZero() && !VirtualBase; }
57 };
58 
59 /// FinalOverriders - Contains the final overrider member functions for all
60 /// member functions in the base subobjects of a class.
61 class FinalOverriders {
62 public:
63  /// OverriderInfo - Information about a final overrider.
64  struct OverriderInfo {
65  /// Method - The method decl of the overrider.
66  const CXXMethodDecl *Method;
67 
68  /// VirtualBase - The virtual base class subobject of this overrider.
69  /// Note that this records the closest derived virtual base class subobject.
70  const CXXRecordDecl *VirtualBase;
71 
72  /// Offset - the base offset of the overrider's parent in the layout class.
74 
75  OverriderInfo() : Method(nullptr), VirtualBase(nullptr),
76  Offset(CharUnits::Zero()) { }
77  };
78 
79 private:
80  /// MostDerivedClass - The most derived class for which the final overriders
81  /// are stored.
82  const CXXRecordDecl *MostDerivedClass;
83 
84  /// MostDerivedClassOffset - If we're building final overriders for a
85  /// construction vtable, this holds the offset from the layout class to the
86  /// most derived class.
87  const CharUnits MostDerivedClassOffset;
88 
89  /// LayoutClass - The class we're using for layout information. Will be
90  /// different than the most derived class if the final overriders are for a
91  /// construction vtable.
92  const CXXRecordDecl *LayoutClass;
93 
94  ASTContext &Context;
95 
96  /// MostDerivedClassLayout - the AST record layout of the most derived class.
97  const ASTRecordLayout &MostDerivedClassLayout;
98 
99  /// MethodBaseOffsetPairTy - Uniquely identifies a member function
100  /// in a base subobject.
101  typedef std::pair<const CXXMethodDecl *, CharUnits> MethodBaseOffsetPairTy;
102 
103  typedef llvm::DenseMap<MethodBaseOffsetPairTy,
104  OverriderInfo> OverridersMapTy;
105 
106  /// OverridersMap - The final overriders for all virtual member functions of
107  /// all the base subobjects of the most derived class.
108  OverridersMapTy OverridersMap;
109 
110  /// SubobjectsToOffsetsMapTy - A mapping from a base subobject (represented
111  /// as a record decl and a subobject number) and its offsets in the most
112  /// derived class as well as the layout class.
113  typedef llvm::DenseMap<std::pair<const CXXRecordDecl *, unsigned>,
114  CharUnits> SubobjectOffsetMapTy;
115 
116  typedef llvm::DenseMap<const CXXRecordDecl *, unsigned> SubobjectCountMapTy;
117 
118  /// ComputeBaseOffsets - Compute the offsets for all base subobjects of the
119  /// given base.
120  void ComputeBaseOffsets(BaseSubobject Base, bool IsVirtual,
121  CharUnits OffsetInLayoutClass,
122  SubobjectOffsetMapTy &SubobjectOffsets,
123  SubobjectOffsetMapTy &SubobjectLayoutClassOffsets,
124  SubobjectCountMapTy &SubobjectCounts);
125 
126  typedef llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBasesSetTy;
127 
128  /// dump - dump the final overriders for a base subobject, and all its direct
129  /// and indirect base subobjects.
130  void dump(raw_ostream &Out, BaseSubobject Base,
131  VisitedVirtualBasesSetTy& VisitedVirtualBases);
132 
133 public:
134  FinalOverriders(const CXXRecordDecl *MostDerivedClass,
135  CharUnits MostDerivedClassOffset,
136  const CXXRecordDecl *LayoutClass);
137 
138  /// getOverrider - Get the final overrider for the given method declaration in
139  /// the subobject with the given base offset.
140  OverriderInfo getOverrider(const CXXMethodDecl *MD,
141  CharUnits BaseOffset) const {
142  assert(OverridersMap.count(std::make_pair(MD, BaseOffset)) &&
143  "Did not find overrider!");
144 
145  return OverridersMap.lookup(std::make_pair(MD, BaseOffset));
146  }
147 
148  /// dump - dump the final overriders.
149  void dump() {
150  VisitedVirtualBasesSetTy VisitedVirtualBases;
151  dump(llvm::errs(), BaseSubobject(MostDerivedClass, CharUnits::Zero()),
152  VisitedVirtualBases);
153  }
154 
155 };
156 
157 FinalOverriders::FinalOverriders(const CXXRecordDecl *MostDerivedClass,
158  CharUnits MostDerivedClassOffset,
159  const CXXRecordDecl *LayoutClass)
160  : MostDerivedClass(MostDerivedClass),
161  MostDerivedClassOffset(MostDerivedClassOffset), LayoutClass(LayoutClass),
162  Context(MostDerivedClass->getASTContext()),
163  MostDerivedClassLayout(Context.getASTRecordLayout(MostDerivedClass)) {
164 
165  // Compute base offsets.
166  SubobjectOffsetMapTy SubobjectOffsets;
167  SubobjectOffsetMapTy SubobjectLayoutClassOffsets;
168  SubobjectCountMapTy SubobjectCounts;
169  ComputeBaseOffsets(BaseSubobject(MostDerivedClass, CharUnits::Zero()),
170  /*IsVirtual=*/false,
171  MostDerivedClassOffset,
172  SubobjectOffsets, SubobjectLayoutClassOffsets,
173  SubobjectCounts);
174 
175  // Get the final overriders.
176  CXXFinalOverriderMap FinalOverriders;
177  MostDerivedClass->getFinalOverriders(FinalOverriders);
178 
179  for (const auto &Overrider : FinalOverriders) {
180  const CXXMethodDecl *MD = Overrider.first;
181  const OverridingMethods &Methods = Overrider.second;
182 
183  for (const auto &M : Methods) {
184  unsigned SubobjectNumber = M.first;
185  assert(SubobjectOffsets.count(std::make_pair(MD->getParent(),
186  SubobjectNumber)) &&
187  "Did not find subobject offset!");
188 
189  CharUnits BaseOffset = SubobjectOffsets[std::make_pair(MD->getParent(),
190  SubobjectNumber)];
191 
192  assert(M.second.size() == 1 && "Final overrider is not unique!");
193  const UniqueVirtualMethod &Method = M.second.front();
194 
195  const CXXRecordDecl *OverriderRD = Method.Method->getParent();
196  assert(SubobjectLayoutClassOffsets.count(
197  std::make_pair(OverriderRD, Method.Subobject))
198  && "Did not find subobject offset!");
199  CharUnits OverriderOffset =
200  SubobjectLayoutClassOffsets[std::make_pair(OverriderRD,
201  Method.Subobject)];
202 
203  OverriderInfo& Overrider = OverridersMap[std::make_pair(MD, BaseOffset)];
204  assert(!Overrider.Method && "Overrider should not exist yet!");
205 
206  Overrider.Offset = OverriderOffset;
207  Overrider.Method = Method.Method;
208  Overrider.VirtualBase = Method.InVirtualSubobject;
209  }
210  }
211 
212 #if DUMP_OVERRIDERS
213  // And dump them (for now).
214  dump();
215 #endif
216 }
217 
218 static BaseOffset ComputeBaseOffset(const ASTContext &Context,
219  const CXXRecordDecl *DerivedRD,
220  const CXXBasePath &Path) {
221  CharUnits NonVirtualOffset = CharUnits::Zero();
222 
223  unsigned NonVirtualStart = 0;
224  const CXXRecordDecl *VirtualBase = nullptr;
225 
226  // First, look for the virtual base class.
227  for (int I = Path.size(), E = 0; I != E; --I) {
228  const CXXBasePathElement &Element = Path[I - 1];
229 
230  if (Element.Base->isVirtual()) {
231  NonVirtualStart = I;
232  QualType VBaseType = Element.Base->getType();
233  VirtualBase = VBaseType->getAsCXXRecordDecl();
234  break;
235  }
236  }
237 
238  // Now compute the non-virtual offset.
239  for (unsigned I = NonVirtualStart, E = Path.size(); I != E; ++I) {
240  const CXXBasePathElement &Element = Path[I];
241 
242  // Check the base class offset.
243  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Element.Class);
244 
245  const CXXRecordDecl *Base = Element.Base->getType()->getAsCXXRecordDecl();
246 
247  NonVirtualOffset += Layout.getBaseClassOffset(Base);
248  }
249 
250  // FIXME: This should probably use CharUnits or something. Maybe we should
251  // even change the base offsets in ASTRecordLayout to be specified in
252  // CharUnits.
253  return BaseOffset(DerivedRD, VirtualBase, NonVirtualOffset);
254 
255 }
256 
257 static BaseOffset ComputeBaseOffset(const ASTContext &Context,
258  const CXXRecordDecl *BaseRD,
259  const CXXRecordDecl *DerivedRD) {
260  CXXBasePaths Paths(/*FindAmbiguities=*/false,
261  /*RecordPaths=*/true, /*DetectVirtual=*/false);
262 
263  if (!DerivedRD->isDerivedFrom(BaseRD, Paths))
264  llvm_unreachable("Class must be derived from the passed in base class!");
265 
266  return ComputeBaseOffset(Context, DerivedRD, Paths.front());
267 }
268 
269 static BaseOffset
270 ComputeReturnAdjustmentBaseOffset(ASTContext &Context,
271  const CXXMethodDecl *DerivedMD,
272  const CXXMethodDecl *BaseMD) {
273  const auto *BaseFT = BaseMD->getType()->castAs<FunctionType>();
274  const auto *DerivedFT = DerivedMD->getType()->castAs<FunctionType>();
275 
276  // Canonicalize the return types.
277  CanQualType CanDerivedReturnType =
278  Context.getCanonicalType(DerivedFT->getReturnType());
279  CanQualType CanBaseReturnType =
280  Context.getCanonicalType(BaseFT->getReturnType());
281 
282  assert(CanDerivedReturnType->getTypeClass() ==
283  CanBaseReturnType->getTypeClass() &&
284  "Types must have same type class!");
285 
286  if (CanDerivedReturnType == CanBaseReturnType) {
287  // No adjustment needed.
288  return BaseOffset();
289  }
290 
291  if (isa<ReferenceType>(CanDerivedReturnType)) {
292  CanDerivedReturnType =
293  CanDerivedReturnType->getAs<ReferenceType>()->getPointeeType();
294  CanBaseReturnType =
295  CanBaseReturnType->getAs<ReferenceType>()->getPointeeType();
296  } else if (isa<PointerType>(CanDerivedReturnType)) {
297  CanDerivedReturnType =
298  CanDerivedReturnType->getAs<PointerType>()->getPointeeType();
299  CanBaseReturnType =
300  CanBaseReturnType->getAs<PointerType>()->getPointeeType();
301  } else {
302  llvm_unreachable("Unexpected return type!");
303  }
304 
305  // We need to compare unqualified types here; consider
306  // const T *Base::foo();
307  // T *Derived::foo();
308  if (CanDerivedReturnType.getUnqualifiedType() ==
309  CanBaseReturnType.getUnqualifiedType()) {
310  // No adjustment needed.
311  return BaseOffset();
312  }
313 
314  const CXXRecordDecl *DerivedRD =
315  cast<CXXRecordDecl>(cast<RecordType>(CanDerivedReturnType)->getDecl());
316 
317  const CXXRecordDecl *BaseRD =
318  cast<CXXRecordDecl>(cast<RecordType>(CanBaseReturnType)->getDecl());
319 
320  return ComputeBaseOffset(Context, BaseRD, DerivedRD);
321 }
322 
323 void
324 FinalOverriders::ComputeBaseOffsets(BaseSubobject Base, bool IsVirtual,
325  CharUnits OffsetInLayoutClass,
326  SubobjectOffsetMapTy &SubobjectOffsets,
327  SubobjectOffsetMapTy &SubobjectLayoutClassOffsets,
328  SubobjectCountMapTy &SubobjectCounts) {
329  const CXXRecordDecl *RD = Base.getBase();
330 
331  unsigned SubobjectNumber = 0;
332  if (!IsVirtual)
333  SubobjectNumber = ++SubobjectCounts[RD];
334 
335  // Set up the subobject to offset mapping.
336  assert(!SubobjectOffsets.count(std::make_pair(RD, SubobjectNumber))
337  && "Subobject offset already exists!");
338  assert(!SubobjectLayoutClassOffsets.count(std::make_pair(RD, SubobjectNumber))
339  && "Subobject offset already exists!");
340 
341  SubobjectOffsets[std::make_pair(RD, SubobjectNumber)] = Base.getBaseOffset();
342  SubobjectLayoutClassOffsets[std::make_pair(RD, SubobjectNumber)] =
343  OffsetInLayoutClass;
344 
345  // Traverse our bases.
346  for (const auto &B : RD->bases()) {
347  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
348 
349  CharUnits BaseOffset;
350  CharUnits BaseOffsetInLayoutClass;
351  if (B.isVirtual()) {
352  // Check if we've visited this virtual base before.
353  if (SubobjectOffsets.count(std::make_pair(BaseDecl, 0)))
354  continue;
355 
356  const ASTRecordLayout &LayoutClassLayout =
357  Context.getASTRecordLayout(LayoutClass);
358 
359  BaseOffset = MostDerivedClassLayout.getVBaseClassOffset(BaseDecl);
360  BaseOffsetInLayoutClass =
361  LayoutClassLayout.getVBaseClassOffset(BaseDecl);
362  } else {
363  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
364  CharUnits Offset = Layout.getBaseClassOffset(BaseDecl);
365 
366  BaseOffset = Base.getBaseOffset() + Offset;
367  BaseOffsetInLayoutClass = OffsetInLayoutClass + Offset;
368  }
369 
370  ComputeBaseOffsets(BaseSubobject(BaseDecl, BaseOffset),
371  B.isVirtual(), BaseOffsetInLayoutClass,
372  SubobjectOffsets, SubobjectLayoutClassOffsets,
373  SubobjectCounts);
374  }
375 }
376 
377 void FinalOverriders::dump(raw_ostream &Out, BaseSubobject Base,
378  VisitedVirtualBasesSetTy &VisitedVirtualBases) {
379  const CXXRecordDecl *RD = Base.getBase();
380  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
381 
382  for (const auto &B : RD->bases()) {
383  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
384 
385  // Ignore bases that don't have any virtual member functions.
386  if (!BaseDecl->isPolymorphic())
387  continue;
388 
389  CharUnits BaseOffset;
390  if (B.isVirtual()) {
391  if (!VisitedVirtualBases.insert(BaseDecl).second) {
392  // We've visited this base before.
393  continue;
394  }
395 
396  BaseOffset = MostDerivedClassLayout.getVBaseClassOffset(BaseDecl);
397  } else {
398  BaseOffset = Layout.getBaseClassOffset(BaseDecl) + Base.getBaseOffset();
399  }
400 
401  dump(Out, BaseSubobject(BaseDecl, BaseOffset), VisitedVirtualBases);
402  }
403 
404  Out << "Final overriders for (";
405  RD->printQualifiedName(Out);
406  Out << ", ";
407  Out << Base.getBaseOffset().getQuantity() << ")\n";
408 
409  // Now dump the overriders for this base subobject.
410  for (const auto *MD : RD->methods()) {
412  continue;
413  MD = MD->getCanonicalDecl();
414 
415  OverriderInfo Overrider = getOverrider(MD, Base.getBaseOffset());
416 
417  Out << " ";
418  MD->printQualifiedName(Out);
419  Out << " - (";
420  Overrider.Method->printQualifiedName(Out);
421  Out << ", " << Overrider.Offset.getQuantity() << ')';
422 
423  BaseOffset Offset;
424  if (!Overrider.Method->isPure())
425  Offset = ComputeReturnAdjustmentBaseOffset(Context, Overrider.Method, MD);
426 
427  if (!Offset.isEmpty()) {
428  Out << " [ret-adj: ";
429  if (Offset.VirtualBase) {
430  Offset.VirtualBase->printQualifiedName(Out);
431  Out << " vbase, ";
432  }
433 
434  Out << Offset.NonVirtualOffset.getQuantity() << " nv]";
435  }
436 
437  Out << "\n";
438  }
439 }
440 
441 /// VCallOffsetMap - Keeps track of vcall offsets when building a vtable.
442 struct VCallOffsetMap {
443 
444  typedef std::pair<const CXXMethodDecl *, CharUnits> MethodAndOffsetPairTy;
445 
446  /// Offsets - Keeps track of methods and their offsets.
447  // FIXME: This should be a real map and not a vector.
449 
450  /// MethodsCanShareVCallOffset - Returns whether two virtual member functions
451  /// can share the same vcall offset.
452  static bool MethodsCanShareVCallOffset(const CXXMethodDecl *LHS,
453  const CXXMethodDecl *RHS);
454 
455 public:
456  /// AddVCallOffset - Adds a vcall offset to the map. Returns true if the
457  /// add was successful, or false if there was already a member function with
458  /// the same signature in the map.
459  bool AddVCallOffset(const CXXMethodDecl *MD, CharUnits OffsetOffset);
460 
461  /// getVCallOffsetOffset - Returns the vcall offset offset (relative to the
462  /// vtable address point) for the given virtual member function.
463  CharUnits getVCallOffsetOffset(const CXXMethodDecl *MD);
464 
465  // empty - Return whether the offset map is empty or not.
466  bool empty() const { return Offsets.empty(); }
467 };
468 
469 static bool HasSameVirtualSignature(const CXXMethodDecl *LHS,
470  const CXXMethodDecl *RHS) {
471  const FunctionProtoType *LT =
472  cast<FunctionProtoType>(LHS->getType().getCanonicalType());
473  const FunctionProtoType *RT =
474  cast<FunctionProtoType>(RHS->getType().getCanonicalType());
475 
476  // Fast-path matches in the canonical types.
477  if (LT == RT) return true;
478 
479  // Force the signatures to match. We can't rely on the overrides
480  // list here because there isn't necessarily an inheritance
481  // relationship between the two methods.
482  if (LT->getMethodQuals() != RT->getMethodQuals())
483  return false;
484  return LT->getParamTypes() == RT->getParamTypes();
485 }
486 
487 bool VCallOffsetMap::MethodsCanShareVCallOffset(const CXXMethodDecl *LHS,
488  const CXXMethodDecl *RHS) {
489  assert(VTableContextBase::hasVtableSlot(LHS) && "LHS must be virtual!");
490  assert(VTableContextBase::hasVtableSlot(RHS) && "LHS must be virtual!");
491 
492  // A destructor can share a vcall offset with another destructor.
493  if (isa<CXXDestructorDecl>(LHS))
494  return isa<CXXDestructorDecl>(RHS);
495 
496  // FIXME: We need to check more things here.
497 
498  // The methods must have the same name.
499  DeclarationName LHSName = LHS->getDeclName();
500  DeclarationName RHSName = RHS->getDeclName();
501  if (LHSName != RHSName)
502  return false;
503 
504  // And the same signatures.
505  return HasSameVirtualSignature(LHS, RHS);
506 }
507 
508 bool VCallOffsetMap::AddVCallOffset(const CXXMethodDecl *MD,
509  CharUnits OffsetOffset) {
510  // Check if we can reuse an offset.
511  for (const auto &OffsetPair : Offsets) {
512  if (MethodsCanShareVCallOffset(OffsetPair.first, MD))
513  return false;
514  }
515 
516  // Add the offset.
517  Offsets.push_back(MethodAndOffsetPairTy(MD, OffsetOffset));
518  return true;
519 }
520 
521 CharUnits VCallOffsetMap::getVCallOffsetOffset(const CXXMethodDecl *MD) {
522  // Look for an offset.
523  for (const auto &OffsetPair : Offsets) {
524  if (MethodsCanShareVCallOffset(OffsetPair.first, MD))
525  return OffsetPair.second;
526  }
527 
528  llvm_unreachable("Should always find a vcall offset offset!");
529 }
530 
531 /// VCallAndVBaseOffsetBuilder - Class for building vcall and vbase offsets.
532 class VCallAndVBaseOffsetBuilder {
533 public:
534  typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits>
535  VBaseOffsetOffsetsMapTy;
536 
537 private:
538  const ItaniumVTableContext &VTables;
539 
540  /// MostDerivedClass - The most derived class for which we're building vcall
541  /// and vbase offsets.
542  const CXXRecordDecl *MostDerivedClass;
543 
544  /// LayoutClass - The class we're using for layout information. Will be
545  /// different than the most derived class if we're building a construction
546  /// vtable.
547  const CXXRecordDecl *LayoutClass;
548 
549  /// Context - The ASTContext which we will use for layout information.
550  ASTContext &Context;
551 
552  /// Components - vcall and vbase offset components
553  typedef SmallVector<VTableComponent, 64> VTableComponentVectorTy;
554  VTableComponentVectorTy Components;
555 
556  /// VisitedVirtualBases - Visited virtual bases.
558 
559  /// VCallOffsets - Keeps track of vcall offsets.
560  VCallOffsetMap VCallOffsets;
561 
562 
563  /// VBaseOffsetOffsets - Contains the offsets of the virtual base offsets,
564  /// relative to the address point.
565  VBaseOffsetOffsetsMapTy VBaseOffsetOffsets;
566 
567  /// FinalOverriders - The final overriders of the most derived class.
568  /// (Can be null when we're not building a vtable of the most derived class).
569  const FinalOverriders *Overriders;
570 
571  /// AddVCallAndVBaseOffsets - Add vcall offsets and vbase offsets for the
572  /// given base subobject.
573  void AddVCallAndVBaseOffsets(BaseSubobject Base, bool BaseIsVirtual,
574  CharUnits RealBaseOffset);
575 
576  /// AddVCallOffsets - Add vcall offsets for the given base subobject.
577  void AddVCallOffsets(BaseSubobject Base, CharUnits VBaseOffset);
578 
579  /// AddVBaseOffsets - Add vbase offsets for the given class.
580  void AddVBaseOffsets(const CXXRecordDecl *Base,
581  CharUnits OffsetInLayoutClass);
582 
583  /// getCurrentOffsetOffset - Get the current vcall or vbase offset offset in
584  /// chars, relative to the vtable address point.
585  CharUnits getCurrentOffsetOffset() const;
586 
587 public:
588  VCallAndVBaseOffsetBuilder(const ItaniumVTableContext &VTables,
589  const CXXRecordDecl *MostDerivedClass,
590  const CXXRecordDecl *LayoutClass,
591  const FinalOverriders *Overriders,
592  BaseSubobject Base, bool BaseIsVirtual,
593  CharUnits OffsetInLayoutClass)
594  : VTables(VTables), MostDerivedClass(MostDerivedClass),
595  LayoutClass(LayoutClass), Context(MostDerivedClass->getASTContext()),
596  Overriders(Overriders) {
597 
598  // Add vcall and vbase offsets.
599  AddVCallAndVBaseOffsets(Base, BaseIsVirtual, OffsetInLayoutClass);
600  }
601 
602  /// Methods for iterating over the components.
603  typedef VTableComponentVectorTy::const_reverse_iterator const_iterator;
604  const_iterator components_begin() const { return Components.rbegin(); }
605  const_iterator components_end() const { return Components.rend(); }
606 
607  const VCallOffsetMap &getVCallOffsets() const { return VCallOffsets; }
608  const VBaseOffsetOffsetsMapTy &getVBaseOffsetOffsets() const {
609  return VBaseOffsetOffsets;
610  }
611 };
612 
613 void
614 VCallAndVBaseOffsetBuilder::AddVCallAndVBaseOffsets(BaseSubobject Base,
615  bool BaseIsVirtual,
616  CharUnits RealBaseOffset) {
617  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base.getBase());
618 
619  // Itanium C++ ABI 2.5.2:
620  // ..in classes sharing a virtual table with a primary base class, the vcall
621  // and vbase offsets added by the derived class all come before the vcall
622  // and vbase offsets required by the base class, so that the latter may be
623  // laid out as required by the base class without regard to additions from
624  // the derived class(es).
625 
626  // (Since we're emitting the vcall and vbase offsets in reverse order, we'll
627  // emit them for the primary base first).
628  if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
629  bool PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual();
630 
631  CharUnits PrimaryBaseOffset;
632 
633  // Get the base offset of the primary base.
634  if (PrimaryBaseIsVirtual) {
635  assert(Layout.getVBaseClassOffset(PrimaryBase).isZero() &&
636  "Primary vbase should have a zero offset!");
637 
638  const ASTRecordLayout &MostDerivedClassLayout =
639  Context.getASTRecordLayout(MostDerivedClass);
640 
641  PrimaryBaseOffset =
642  MostDerivedClassLayout.getVBaseClassOffset(PrimaryBase);
643  } else {
644  assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
645  "Primary base should have a zero offset!");
646 
647  PrimaryBaseOffset = Base.getBaseOffset();
648  }
649 
650  AddVCallAndVBaseOffsets(
651  BaseSubobject(PrimaryBase,PrimaryBaseOffset),
652  PrimaryBaseIsVirtual, RealBaseOffset);
653  }
654 
655  AddVBaseOffsets(Base.getBase(), RealBaseOffset);
656 
657  // We only want to add vcall offsets for virtual bases.
658  if (BaseIsVirtual)
659  AddVCallOffsets(Base, RealBaseOffset);
660 }
661 
662 CharUnits VCallAndVBaseOffsetBuilder::getCurrentOffsetOffset() const {
663  // OffsetIndex is the index of this vcall or vbase offset, relative to the
664  // vtable address point. (We subtract 3 to account for the information just
665  // above the address point, the RTTI info, the offset to top, and the
666  // vcall offset itself).
667  int64_t OffsetIndex = -(int64_t)(3 + Components.size());
668 
669  // Under the relative ABI, the offset widths are 32-bit ints instead of
670  // pointer widths.
671  CharUnits OffsetWidth = Context.toCharUnitsFromBits(
672  VTables.isRelativeLayout() ? 32
673  : Context.getTargetInfo().getPointerWidth(0));
674  CharUnits OffsetOffset = OffsetWidth * OffsetIndex;
675 
676  return OffsetOffset;
677 }
678 
679 void VCallAndVBaseOffsetBuilder::AddVCallOffsets(BaseSubobject Base,
680  CharUnits VBaseOffset) {
681  const CXXRecordDecl *RD = Base.getBase();
682  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
683 
684  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
685 
686  // Handle the primary base first.
687  // We only want to add vcall offsets if the base is non-virtual; a virtual
688  // primary base will have its vcall and vbase offsets emitted already.
689  if (PrimaryBase && !Layout.isPrimaryBaseVirtual()) {
690  // Get the base offset of the primary base.
691  assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
692  "Primary base should have a zero offset!");
693 
694  AddVCallOffsets(BaseSubobject(PrimaryBase, Base.getBaseOffset()),
695  VBaseOffset);
696  }
697 
698  // Add the vcall offsets.
699  for (const auto *MD : RD->methods()) {
701  continue;
702  MD = MD->getCanonicalDecl();
703 
704  CharUnits OffsetOffset = getCurrentOffsetOffset();
705 
706  // Don't add a vcall offset if we already have one for this member function
707  // signature.
708  if (!VCallOffsets.AddVCallOffset(MD, OffsetOffset))
709  continue;
710 
712 
713  if (Overriders) {
714  // Get the final overrider.
715  FinalOverriders::OverriderInfo Overrider =
716  Overriders->getOverrider(MD, Base.getBaseOffset());
717 
718  /// The vcall offset is the offset from the virtual base to the object
719  /// where the function was overridden.
720  Offset = Overrider.Offset - VBaseOffset;
721  }
722 
723  Components.push_back(
725  }
726 
727  // And iterate over all non-virtual bases (ignoring the primary base).
728  for (const auto &B : RD->bases()) {
729  if (B.isVirtual())
730  continue;
731 
732  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
733  if (BaseDecl == PrimaryBase)
734  continue;
735 
736  // Get the base offset of this base.
737  CharUnits BaseOffset = Base.getBaseOffset() +
738  Layout.getBaseClassOffset(BaseDecl);
739 
740  AddVCallOffsets(BaseSubobject(BaseDecl, BaseOffset),
741  VBaseOffset);
742  }
743 }
744 
745 void
746 VCallAndVBaseOffsetBuilder::AddVBaseOffsets(const CXXRecordDecl *RD,
747  CharUnits OffsetInLayoutClass) {
748  const ASTRecordLayout &LayoutClassLayout =
749  Context.getASTRecordLayout(LayoutClass);
750 
751  // Add vbase offsets.
752  for (const auto &B : RD->bases()) {
753  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
754 
755  // Check if this is a virtual base that we haven't visited before.
756  if (B.isVirtual() && VisitedVirtualBases.insert(BaseDecl).second) {
757  CharUnits Offset =
758  LayoutClassLayout.getVBaseClassOffset(BaseDecl) - OffsetInLayoutClass;
759 
760  // Add the vbase offset offset.
761  assert(!VBaseOffsetOffsets.count(BaseDecl) &&
762  "vbase offset offset already exists!");
763 
764  CharUnits VBaseOffsetOffset = getCurrentOffsetOffset();
765  VBaseOffsetOffsets.insert(
766  std::make_pair(BaseDecl, VBaseOffsetOffset));
767 
768  Components.push_back(
770  }
771 
772  // Check the base class looking for more vbase offsets.
773  AddVBaseOffsets(BaseDecl, OffsetInLayoutClass);
774  }
775 }
776 
777 /// ItaniumVTableBuilder - Class for building vtable layout information.
778 class ItaniumVTableBuilder {
779 public:
780  /// PrimaryBasesSetVectorTy - A set vector of direct and indirect
781  /// primary bases.
783  PrimaryBasesSetVectorTy;
784 
785  typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits>
786  VBaseOffsetOffsetsMapTy;
787 
788  typedef VTableLayout::AddressPointsMapTy AddressPointsMapTy;
789 
790  typedef llvm::DenseMap<GlobalDecl, int64_t> MethodVTableIndicesTy;
791 
792 private:
793  /// VTables - Global vtable information.
794  ItaniumVTableContext &VTables;
795 
796  /// MostDerivedClass - The most derived class for which we're building this
797  /// vtable.
798  const CXXRecordDecl *MostDerivedClass;
799 
800  /// MostDerivedClassOffset - If we're building a construction vtable, this
801  /// holds the offset from the layout class to the most derived class.
802  const CharUnits MostDerivedClassOffset;
803 
804  /// MostDerivedClassIsVirtual - Whether the most derived class is a virtual
805  /// base. (This only makes sense when building a construction vtable).
806  bool MostDerivedClassIsVirtual;
807 
808  /// LayoutClass - The class we're using for layout information. Will be
809  /// different than the most derived class if we're building a construction
810  /// vtable.
811  const CXXRecordDecl *LayoutClass;
812 
813  /// Context - The ASTContext which we will use for layout information.
814  ASTContext &Context;
815 
816  /// FinalOverriders - The final overriders of the most derived class.
817  const FinalOverriders Overriders;
818 
819  /// VCallOffsetsForVBases - Keeps track of vcall offsets for the virtual
820  /// bases in this vtable.
821  llvm::DenseMap<const CXXRecordDecl *, VCallOffsetMap> VCallOffsetsForVBases;
822 
823  /// VBaseOffsetOffsets - Contains the offsets of the virtual base offsets for
824  /// the most derived class.
825  VBaseOffsetOffsetsMapTy VBaseOffsetOffsets;
826 
827  /// Components - The components of the vtable being built.
829 
830  /// AddressPoints - Address points for the vtable being built.
831  AddressPointsMapTy AddressPoints;
832 
833  /// MethodInfo - Contains information about a method in a vtable.
834  /// (Used for computing 'this' pointer adjustment thunks.
835  struct MethodInfo {
836  /// BaseOffset - The base offset of this method.
837  const CharUnits BaseOffset;
838 
839  /// BaseOffsetInLayoutClass - The base offset in the layout class of this
840  /// method.
841  const CharUnits BaseOffsetInLayoutClass;
842 
843  /// VTableIndex - The index in the vtable that this method has.
844  /// (For destructors, this is the index of the complete destructor).
845  const uint64_t VTableIndex;
846 
847  MethodInfo(CharUnits BaseOffset, CharUnits BaseOffsetInLayoutClass,
848  uint64_t VTableIndex)
849  : BaseOffset(BaseOffset),
850  BaseOffsetInLayoutClass(BaseOffsetInLayoutClass),
851  VTableIndex(VTableIndex) { }
852 
853  MethodInfo()
854  : BaseOffset(CharUnits::Zero()),
855  BaseOffsetInLayoutClass(CharUnits::Zero()),
856  VTableIndex(0) { }
857 
858  MethodInfo(MethodInfo const&) = default;
859  };
860 
861  typedef llvm::DenseMap<const CXXMethodDecl *, MethodInfo> MethodInfoMapTy;
862 
863  /// MethodInfoMap - The information for all methods in the vtable we're
864  /// currently building.
865  MethodInfoMapTy MethodInfoMap;
866 
867  /// MethodVTableIndices - Contains the index (relative to the vtable address
868  /// point) where the function pointer for a virtual function is stored.
869  MethodVTableIndicesTy MethodVTableIndices;
870 
871  typedef llvm::DenseMap<uint64_t, ThunkInfo> VTableThunksMapTy;
872 
873  /// VTableThunks - The thunks by vtable index in the vtable currently being
874  /// built.
875  VTableThunksMapTy VTableThunks;
876 
877  typedef SmallVector<ThunkInfo, 1> ThunkInfoVectorTy;
878  typedef llvm::DenseMap<const CXXMethodDecl *, ThunkInfoVectorTy> ThunksMapTy;
879 
880  /// Thunks - A map that contains all the thunks needed for all methods in the
881  /// most derived class for which the vtable is currently being built.
882  ThunksMapTy Thunks;
883 
884  /// AddThunk - Add a thunk for the given method.
885  void AddThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk);
886 
887  /// ComputeThisAdjustments - Compute the 'this' pointer adjustments for the
888  /// part of the vtable we're currently building.
889  void ComputeThisAdjustments();
890 
891  typedef llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBasesSetTy;
892 
893  /// PrimaryVirtualBases - All known virtual bases who are a primary base of
894  /// some other base.
895  VisitedVirtualBasesSetTy PrimaryVirtualBases;
896 
897  /// ComputeReturnAdjustment - Compute the return adjustment given a return
898  /// adjustment base offset.
899  ReturnAdjustment ComputeReturnAdjustment(BaseOffset Offset);
900 
901  /// ComputeThisAdjustmentBaseOffset - Compute the base offset for adjusting
902  /// the 'this' pointer from the base subobject to the derived subobject.
903  BaseOffset ComputeThisAdjustmentBaseOffset(BaseSubobject Base,
904  BaseSubobject Derived) const;
905 
906  /// ComputeThisAdjustment - Compute the 'this' pointer adjustment for the
907  /// given virtual member function, its offset in the layout class and its
908  /// final overrider.
910  ComputeThisAdjustment(const CXXMethodDecl *MD,
911  CharUnits BaseOffsetInLayoutClass,
912  FinalOverriders::OverriderInfo Overrider);
913 
914  /// AddMethod - Add a single virtual member function to the vtable
915  /// components vector.
916  void AddMethod(const CXXMethodDecl *MD, ReturnAdjustment ReturnAdjustment);
917 
918  /// IsOverriderUsed - Returns whether the overrider will ever be used in this
919  /// part of the vtable.
920  ///
921  /// Itanium C++ ABI 2.5.2:
922  ///
923  /// struct A { virtual void f(); };
924  /// struct B : virtual public A { int i; };
925  /// struct C : virtual public A { int j; };
926  /// struct D : public B, public C {};
927  ///
928  /// When B and C are declared, A is a primary base in each case, so although
929  /// vcall offsets are allocated in the A-in-B and A-in-C vtables, no this
930  /// adjustment is required and no thunk is generated. However, inside D
931  /// objects, A is no longer a primary base of C, so if we allowed calls to
932  /// C::f() to use the copy of A's vtable in the C subobject, we would need
933  /// to adjust this from C* to B::A*, which would require a third-party
934  /// thunk. Since we require that a call to C::f() first convert to A*,
935  /// C-in-D's copy of A's vtable is never referenced, so this is not
936  /// necessary.
937  bool IsOverriderUsed(const CXXMethodDecl *Overrider,
938  CharUnits BaseOffsetInLayoutClass,
939  const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
940  CharUnits FirstBaseOffsetInLayoutClass) const;
941 
942 
943  /// AddMethods - Add the methods of this base subobject and all its
944  /// primary bases to the vtable components vector.
945  void AddMethods(BaseSubobject Base, CharUnits BaseOffsetInLayoutClass,
946  const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
947  CharUnits FirstBaseOffsetInLayoutClass,
948  PrimaryBasesSetVectorTy &PrimaryBases);
949 
950  // LayoutVTable - Layout the vtable for the given base class, including its
951  // secondary vtables and any vtables for virtual bases.
952  void LayoutVTable();
953 
954  /// LayoutPrimaryAndSecondaryVTables - Layout the primary vtable for the
955  /// given base subobject, as well as all its secondary vtables.
956  ///
957  /// \param BaseIsMorallyVirtual whether the base subobject is a virtual base
958  /// or a direct or indirect base of a virtual base.
959  ///
960  /// \param BaseIsVirtualInLayoutClass - Whether the base subobject is virtual
961  /// in the layout class.
962  void LayoutPrimaryAndSecondaryVTables(BaseSubobject Base,
963  bool BaseIsMorallyVirtual,
964  bool BaseIsVirtualInLayoutClass,
965  CharUnits OffsetInLayoutClass);
966 
967  /// LayoutSecondaryVTables - Layout the secondary vtables for the given base
968  /// subobject.
969  ///
970  /// \param BaseIsMorallyVirtual whether the base subobject is a virtual base
971  /// or a direct or indirect base of a virtual base.
972  void LayoutSecondaryVTables(BaseSubobject Base, bool BaseIsMorallyVirtual,
973  CharUnits OffsetInLayoutClass);
974 
975  /// DeterminePrimaryVirtualBases - Determine the primary virtual bases in this
976  /// class hierarchy.
977  void DeterminePrimaryVirtualBases(const CXXRecordDecl *RD,
978  CharUnits OffsetInLayoutClass,
979  VisitedVirtualBasesSetTy &VBases);
980 
981  /// LayoutVTablesForVirtualBases - Layout vtables for all virtual bases of the
982  /// given base (excluding any primary bases).
983  void LayoutVTablesForVirtualBases(const CXXRecordDecl *RD,
984  VisitedVirtualBasesSetTy &VBases);
985 
986  /// isBuildingConstructionVTable - Return whether this vtable builder is
987  /// building a construction vtable.
988  bool isBuildingConstructorVTable() const {
989  return MostDerivedClass != LayoutClass;
990  }
991 
992 public:
993  /// Component indices of the first component of each of the vtables in the
994  /// vtable group.
995  SmallVector<size_t, 4> VTableIndices;
996 
997  ItaniumVTableBuilder(ItaniumVTableContext &VTables,
998  const CXXRecordDecl *MostDerivedClass,
999  CharUnits MostDerivedClassOffset,
1000  bool MostDerivedClassIsVirtual,
1001  const CXXRecordDecl *LayoutClass)
1002  : VTables(VTables), MostDerivedClass(MostDerivedClass),
1003  MostDerivedClassOffset(MostDerivedClassOffset),
1004  MostDerivedClassIsVirtual(MostDerivedClassIsVirtual),
1005  LayoutClass(LayoutClass), Context(MostDerivedClass->getASTContext()),
1006  Overriders(MostDerivedClass, MostDerivedClassOffset, LayoutClass) {
1007  assert(!Context.getTargetInfo().getCXXABI().isMicrosoft());
1008 
1009  LayoutVTable();
1010 
1011  if (Context.getLangOpts().DumpVTableLayouts)
1012  dumpLayout(llvm::outs());
1013  }
1014 
1015  uint64_t getNumThunks() const {
1016  return Thunks.size();
1017  }
1018 
1019  ThunksMapTy::const_iterator thunks_begin() const {
1020  return Thunks.begin();
1021  }
1022 
1023  ThunksMapTy::const_iterator thunks_end() const {
1024  return Thunks.end();
1025  }
1026 
1027  const VBaseOffsetOffsetsMapTy &getVBaseOffsetOffsets() const {
1028  return VBaseOffsetOffsets;
1029  }
1030 
1031  const AddressPointsMapTy &getAddressPoints() const {
1032  return AddressPoints;
1033  }
1034 
1035  MethodVTableIndicesTy::const_iterator vtable_indices_begin() const {
1036  return MethodVTableIndices.begin();
1037  }
1038 
1039  MethodVTableIndicesTy::const_iterator vtable_indices_end() const {
1040  return MethodVTableIndices.end();
1041  }
1042 
1043  ArrayRef<VTableComponent> vtable_components() const { return Components; }
1044 
1045  AddressPointsMapTy::const_iterator address_points_begin() const {
1046  return AddressPoints.begin();
1047  }
1048 
1049  AddressPointsMapTy::const_iterator address_points_end() const {
1050  return AddressPoints.end();
1051  }
1052 
1053  VTableThunksMapTy::const_iterator vtable_thunks_begin() const {
1054  return VTableThunks.begin();
1055  }
1056 
1057  VTableThunksMapTy::const_iterator vtable_thunks_end() const {
1058  return VTableThunks.end();
1059  }
1060 
1061  /// dumpLayout - Dump the vtable layout.
1062  void dumpLayout(raw_ostream&);
1063 };
1064 
1065 void ItaniumVTableBuilder::AddThunk(const CXXMethodDecl *MD,
1066  const ThunkInfo &Thunk) {
1067  assert(!isBuildingConstructorVTable() &&
1068  "Can't add thunks for construction vtable");
1069 
1070  SmallVectorImpl<ThunkInfo> &ThunksVector = Thunks[MD];
1071 
1072  // Check if we have this thunk already.
1073  if (llvm::find(ThunksVector, Thunk) != ThunksVector.end())
1074  return;
1075 
1076  ThunksVector.push_back(Thunk);
1077 }
1078 
1079 typedef llvm::SmallPtrSet<const CXXMethodDecl *, 8> OverriddenMethodsSetTy;
1080 
1081 /// Visit all the methods overridden by the given method recursively,
1082 /// in a depth-first pre-order. The Visitor's visitor method returns a bool
1083 /// indicating whether to continue the recursion for the given overridden
1084 /// method (i.e. returning false stops the iteration).
1085 template <class VisitorTy>
1086 static void
1087 visitAllOverriddenMethods(const CXXMethodDecl *MD, VisitorTy &Visitor) {
1088  assert(VTableContextBase::hasVtableSlot(MD) && "Method is not virtual!");
1089 
1090  for (const CXXMethodDecl *OverriddenMD : MD->overridden_methods()) {
1091  if (!Visitor(OverriddenMD))
1092  continue;
1093  visitAllOverriddenMethods(OverriddenMD, Visitor);
1094  }
1095 }
1096 
1097 /// ComputeAllOverriddenMethods - Given a method decl, will return a set of all
1098 /// the overridden methods that the function decl overrides.
1099 static void
1100 ComputeAllOverriddenMethods(const CXXMethodDecl *MD,
1101  OverriddenMethodsSetTy& OverriddenMethods) {
1102  auto OverriddenMethodsCollector = [&](const CXXMethodDecl *MD) {
1103  // Don't recurse on this method if we've already collected it.
1104  return OverriddenMethods.insert(MD).second;
1105  };
1106  visitAllOverriddenMethods(MD, OverriddenMethodsCollector);
1107 }
1108 
1109 void ItaniumVTableBuilder::ComputeThisAdjustments() {
1110  // Now go through the method info map and see if any of the methods need
1111  // 'this' pointer adjustments.
1112  for (const auto &MI : MethodInfoMap) {
1113  const CXXMethodDecl *MD = MI.first;
1114  const MethodInfo &MethodInfo = MI.second;
1115 
1116  // Ignore adjustments for unused function pointers.
1117  uint64_t VTableIndex = MethodInfo.VTableIndex;
1118  if (Components[VTableIndex].getKind() ==
1120  continue;
1121 
1122  // Get the final overrider for this method.
1123  FinalOverriders::OverriderInfo Overrider =
1124  Overriders.getOverrider(MD, MethodInfo.BaseOffset);
1125 
1126  // Check if we need an adjustment at all.
1127  if (MethodInfo.BaseOffsetInLayoutClass == Overrider.Offset) {
1128  // When a return thunk is needed by a derived class that overrides a
1129  // virtual base, gcc uses a virtual 'this' adjustment as well.
1130  // While the thunk itself might be needed by vtables in subclasses or
1131  // in construction vtables, there doesn't seem to be a reason for using
1132  // the thunk in this vtable. Still, we do so to match gcc.
1133  if (VTableThunks.lookup(VTableIndex).Return.isEmpty())
1134  continue;
1135  }
1136 
1138  ComputeThisAdjustment(MD, MethodInfo.BaseOffsetInLayoutClass, Overrider);
1139 
1140  if (ThisAdjustment.isEmpty())
1141  continue;
1142 
1143  // Add it.
1144  VTableThunks[VTableIndex].This = ThisAdjustment;
1145 
1146  if (isa<CXXDestructorDecl>(MD)) {
1147  // Add an adjustment for the deleting destructor as well.
1148  VTableThunks[VTableIndex + 1].This = ThisAdjustment;
1149  }
1150  }
1151 
1152  /// Clear the method info map.
1153  MethodInfoMap.clear();
1154 
1155  if (isBuildingConstructorVTable()) {
1156  // We don't need to store thunk information for construction vtables.
1157  return;
1158  }
1159 
1160  for (const auto &TI : VTableThunks) {
1161  const VTableComponent &Component = Components[TI.first];
1162  const ThunkInfo &Thunk = TI.second;
1163  const CXXMethodDecl *MD;
1164 
1165  switch (Component.getKind()) {
1166  default:
1167  llvm_unreachable("Unexpected vtable component kind!");
1169  MD = Component.getFunctionDecl();
1170  break;
1172  MD = Component.getDestructorDecl();
1173  break;
1175  // We've already added the thunk when we saw the complete dtor pointer.
1176  continue;
1177  }
1178 
1179  if (MD->getParent() == MostDerivedClass)
1180  AddThunk(MD, Thunk);
1181  }
1182 }
1183 
1185 ItaniumVTableBuilder::ComputeReturnAdjustment(BaseOffset Offset) {
1186  ReturnAdjustment Adjustment;
1187 
1188  if (!Offset.isEmpty()) {
1189  if (Offset.VirtualBase) {
1190  // Get the virtual base offset offset.
1191  if (Offset.DerivedClass == MostDerivedClass) {
1192  // We can get the offset offset directly from our map.
1193  Adjustment.Virtual.Itanium.VBaseOffsetOffset =
1194  VBaseOffsetOffsets.lookup(Offset.VirtualBase).getQuantity();
1195  } else {
1196  Adjustment.Virtual.Itanium.VBaseOffsetOffset =
1197  VTables.getVirtualBaseOffsetOffset(Offset.DerivedClass,
1198  Offset.VirtualBase).getQuantity();
1199  }
1200  }
1201 
1202  Adjustment.NonVirtual = Offset.NonVirtualOffset.getQuantity();
1203  }
1204 
1205  return Adjustment;
1206 }
1207 
1208 BaseOffset ItaniumVTableBuilder::ComputeThisAdjustmentBaseOffset(
1209  BaseSubobject Base, BaseSubobject Derived) const {
1210  const CXXRecordDecl *BaseRD = Base.getBase();
1211  const CXXRecordDecl *DerivedRD = Derived.getBase();
1212 
1213  CXXBasePaths Paths(/*FindAmbiguities=*/true,
1214  /*RecordPaths=*/true, /*DetectVirtual=*/true);
1215 
1216  if (!DerivedRD->isDerivedFrom(BaseRD, Paths))
1217  llvm_unreachable("Class must be derived from the passed in base class!");
1218 
1219  // We have to go through all the paths, and see which one leads us to the
1220  // right base subobject.
1221  for (const CXXBasePath &Path : Paths) {
1222  BaseOffset Offset = ComputeBaseOffset(Context, DerivedRD, Path);
1223 
1224  CharUnits OffsetToBaseSubobject = Offset.NonVirtualOffset;
1225 
1226  if (Offset.VirtualBase) {
1227  // If we have a virtual base class, the non-virtual offset is relative
1228  // to the virtual base class offset.
1229  const ASTRecordLayout &LayoutClassLayout =
1230  Context.getASTRecordLayout(LayoutClass);
1231 
1232  /// Get the virtual base offset, relative to the most derived class
1233  /// layout.
1234  OffsetToBaseSubobject +=
1235  LayoutClassLayout.getVBaseClassOffset(Offset.VirtualBase);
1236  } else {
1237  // Otherwise, the non-virtual offset is relative to the derived class
1238  // offset.
1239  OffsetToBaseSubobject += Derived.getBaseOffset();
1240  }
1241 
1242  // Check if this path gives us the right base subobject.
1243  if (OffsetToBaseSubobject == Base.getBaseOffset()) {
1244  // Since we're going from the base class _to_ the derived class, we'll
1245  // invert the non-virtual offset here.
1246  Offset.NonVirtualOffset = -Offset.NonVirtualOffset;
1247  return Offset;
1248  }
1249  }
1250 
1251  return BaseOffset();
1252 }
1253 
1254 ThisAdjustment ItaniumVTableBuilder::ComputeThisAdjustment(
1255  const CXXMethodDecl *MD, CharUnits BaseOffsetInLayoutClass,
1256  FinalOverriders::OverriderInfo Overrider) {
1257  // Ignore adjustments for pure virtual member functions.
1258  if (Overrider.Method->isPure())
1259  return ThisAdjustment();
1260 
1261  BaseSubobject OverriddenBaseSubobject(MD->getParent(),
1262  BaseOffsetInLayoutClass);
1263 
1264  BaseSubobject OverriderBaseSubobject(Overrider.Method->getParent(),
1265  Overrider.Offset);
1266 
1267  // Compute the adjustment offset.
1268  BaseOffset Offset = ComputeThisAdjustmentBaseOffset(OverriddenBaseSubobject,
1269  OverriderBaseSubobject);
1270  if (Offset.isEmpty())
1271  return ThisAdjustment();
1272 
1273  ThisAdjustment Adjustment;
1274 
1275  if (Offset.VirtualBase) {
1276  // Get the vcall offset map for this virtual base.
1277  VCallOffsetMap &VCallOffsets = VCallOffsetsForVBases[Offset.VirtualBase];
1278 
1279  if (VCallOffsets.empty()) {
1280  // We don't have vcall offsets for this virtual base, go ahead and
1281  // build them.
1282  VCallAndVBaseOffsetBuilder Builder(
1283  VTables, MostDerivedClass, MostDerivedClass,
1284  /*Overriders=*/nullptr,
1285  BaseSubobject(Offset.VirtualBase, CharUnits::Zero()),
1286  /*BaseIsVirtual=*/true,
1287  /*OffsetInLayoutClass=*/
1288  CharUnits::Zero());
1289 
1290  VCallOffsets = Builder.getVCallOffsets();
1291  }
1292 
1293  Adjustment.Virtual.Itanium.VCallOffsetOffset =
1294  VCallOffsets.getVCallOffsetOffset(MD).getQuantity();
1295  }
1296 
1297  // Set the non-virtual part of the adjustment.
1298  Adjustment.NonVirtual = Offset.NonVirtualOffset.getQuantity();
1299 
1300  return Adjustment;
1301 }
1302 
1303 void ItaniumVTableBuilder::AddMethod(const CXXMethodDecl *MD,
1305  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1306  assert(ReturnAdjustment.isEmpty() &&
1307  "Destructor can't have return adjustment!");
1308 
1309  // Add both the complete destructor and the deleting destructor.
1310  Components.push_back(VTableComponent::MakeCompleteDtor(DD));
1311  Components.push_back(VTableComponent::MakeDeletingDtor(DD));
1312  } else {
1313  // Add the return adjustment if necessary.
1314  if (!ReturnAdjustment.isEmpty())
1315  VTableThunks[Components.size()].Return = ReturnAdjustment;
1316 
1317  // Add the function.
1318  Components.push_back(VTableComponent::MakeFunction(MD));
1319  }
1320 }
1321 
1322 /// OverridesIndirectMethodInBase - Return whether the given member function
1323 /// overrides any methods in the set of given bases.
1324 /// Unlike OverridesMethodInBase, this checks "overriders of overriders".
1325 /// For example, if we have:
1326 ///
1327 /// struct A { virtual void f(); }
1328 /// struct B : A { virtual void f(); }
1329 /// struct C : B { virtual void f(); }
1330 ///
1331 /// OverridesIndirectMethodInBase will return true if given C::f as the method
1332 /// and { A } as the set of bases.
1333 static bool OverridesIndirectMethodInBases(
1334  const CXXMethodDecl *MD,
1336  if (Bases.count(MD->getParent()))
1337  return true;
1338 
1339  for (const CXXMethodDecl *OverriddenMD : MD->overridden_methods()) {
1340  // Check "indirect overriders".
1341  if (OverridesIndirectMethodInBases(OverriddenMD, Bases))
1342  return true;
1343  }
1344 
1345  return false;
1346 }
1347 
1348 bool ItaniumVTableBuilder::IsOverriderUsed(
1349  const CXXMethodDecl *Overrider, CharUnits BaseOffsetInLayoutClass,
1350  const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
1351  CharUnits FirstBaseOffsetInLayoutClass) const {
1352  // If the base and the first base in the primary base chain have the same
1353  // offsets, then this overrider will be used.
1354  if (BaseOffsetInLayoutClass == FirstBaseOffsetInLayoutClass)
1355  return true;
1356 
1357  // We know now that Base (or a direct or indirect base of it) is a primary
1358  // base in part of the class hierarchy, but not a primary base in the most
1359  // derived class.
1360 
1361  // If the overrider is the first base in the primary base chain, we know
1362  // that the overrider will be used.
1363  if (Overrider->getParent() == FirstBaseInPrimaryBaseChain)
1364  return true;
1365 
1367 
1368  const CXXRecordDecl *RD = FirstBaseInPrimaryBaseChain;
1369  PrimaryBases.insert(RD);
1370 
1371  // Now traverse the base chain, starting with the first base, until we find
1372  // the base that is no longer a primary base.
1373  while (true) {
1374  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1375  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
1376 
1377  if (!PrimaryBase)
1378  break;
1379 
1380  if (Layout.isPrimaryBaseVirtual()) {
1381  assert(Layout.getVBaseClassOffset(PrimaryBase).isZero() &&
1382  "Primary base should always be at offset 0!");
1383 
1384  const ASTRecordLayout &LayoutClassLayout =
1385  Context.getASTRecordLayout(LayoutClass);
1386 
1387  // Now check if this is the primary base that is not a primary base in the
1388  // most derived class.
1389  if (LayoutClassLayout.getVBaseClassOffset(PrimaryBase) !=
1390  FirstBaseOffsetInLayoutClass) {
1391  // We found it, stop walking the chain.
1392  break;
1393  }
1394  } else {
1395  assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
1396  "Primary base should always be at offset 0!");
1397  }
1398 
1399  if (!PrimaryBases.insert(PrimaryBase))
1400  llvm_unreachable("Found a duplicate primary base!");
1401 
1402  RD = PrimaryBase;
1403  }
1404 
1405  // If the final overrider is an override of one of the primary bases,
1406  // then we know that it will be used.
1407  return OverridesIndirectMethodInBases(Overrider, PrimaryBases);
1408 }
1409 
1410 typedef llvm::SmallSetVector<const CXXRecordDecl *, 8> BasesSetVectorTy;
1411 
1412 /// FindNearestOverriddenMethod - Given a method, returns the overridden method
1413 /// from the nearest base. Returns null if no method was found.
1414 /// The Bases are expected to be sorted in a base-to-derived order.
1415 static const CXXMethodDecl *
1416 FindNearestOverriddenMethod(const CXXMethodDecl *MD,
1417  BasesSetVectorTy &Bases) {
1418  OverriddenMethodsSetTy OverriddenMethods;
1419  ComputeAllOverriddenMethods(MD, OverriddenMethods);
1420 
1421  for (const CXXRecordDecl *PrimaryBase :
1422  llvm::make_range(Bases.rbegin(), Bases.rend())) {
1423  // Now check the overridden methods.
1424  for (const CXXMethodDecl *OverriddenMD : OverriddenMethods) {
1425  // We found our overridden method.
1426  if (OverriddenMD->getParent() == PrimaryBase)
1427  return OverriddenMD;
1428  }
1429  }
1430 
1431  return nullptr;
1432 }
1433 
1434 void ItaniumVTableBuilder::AddMethods(
1435  BaseSubobject Base, CharUnits BaseOffsetInLayoutClass,
1436  const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
1437  CharUnits FirstBaseOffsetInLayoutClass,
1438  PrimaryBasesSetVectorTy &PrimaryBases) {
1439  // Itanium C++ ABI 2.5.2:
1440  // The order of the virtual function pointers in a virtual table is the
1441  // order of declaration of the corresponding member functions in the class.
1442  //
1443  // There is an entry for any virtual function declared in a class,
1444  // whether it is a new function or overrides a base class function,
1445  // unless it overrides a function from the primary base, and conversion
1446  // between their return types does not require an adjustment.
1447 
1448  const CXXRecordDecl *RD = Base.getBase();
1449  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1450 
1451  if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
1452  CharUnits PrimaryBaseOffset;
1453  CharUnits PrimaryBaseOffsetInLayoutClass;
1454  if (Layout.isPrimaryBaseVirtual()) {
1455  assert(Layout.getVBaseClassOffset(PrimaryBase).isZero() &&
1456  "Primary vbase should have a zero offset!");
1457 
1458  const ASTRecordLayout &MostDerivedClassLayout =
1459  Context.getASTRecordLayout(MostDerivedClass);
1460 
1461  PrimaryBaseOffset =
1462  MostDerivedClassLayout.getVBaseClassOffset(PrimaryBase);
1463 
1464  const ASTRecordLayout &LayoutClassLayout =
1465  Context.getASTRecordLayout(LayoutClass);
1466 
1467  PrimaryBaseOffsetInLayoutClass =
1468  LayoutClassLayout.getVBaseClassOffset(PrimaryBase);
1469  } else {
1470  assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
1471  "Primary base should have a zero offset!");
1472 
1473  PrimaryBaseOffset = Base.getBaseOffset();
1474  PrimaryBaseOffsetInLayoutClass = BaseOffsetInLayoutClass;
1475  }
1476 
1477  AddMethods(BaseSubobject(PrimaryBase, PrimaryBaseOffset),
1478  PrimaryBaseOffsetInLayoutClass, FirstBaseInPrimaryBaseChain,
1479  FirstBaseOffsetInLayoutClass, PrimaryBases);
1480 
1481  if (!PrimaryBases.insert(PrimaryBase))
1482  llvm_unreachable("Found a duplicate primary base!");
1483  }
1484 
1485  typedef llvm::SmallVector<const CXXMethodDecl *, 8> NewVirtualFunctionsTy;
1486  NewVirtualFunctionsTy NewVirtualFunctions;
1487 
1488  llvm::SmallVector<const CXXMethodDecl*, 4> NewImplicitVirtualFunctions;
1489 
1490  // Now go through all virtual member functions and add them.
1491  for (const auto *MD : RD->methods()) {
1493  continue;
1494  MD = MD->getCanonicalDecl();
1495 
1496  // Get the final overrider.
1497  FinalOverriders::OverriderInfo Overrider =
1498  Overriders.getOverrider(MD, Base.getBaseOffset());
1499 
1500  // Check if this virtual member function overrides a method in a primary
1501  // base. If this is the case, and the return type doesn't require adjustment
1502  // then we can just use the member function from the primary base.
1503  if (const CXXMethodDecl *OverriddenMD =
1504  FindNearestOverriddenMethod(MD, PrimaryBases)) {
1505  if (ComputeReturnAdjustmentBaseOffset(Context, MD,
1506  OverriddenMD).isEmpty()) {
1507  // Replace the method info of the overridden method with our own
1508  // method.
1509  assert(MethodInfoMap.count(OverriddenMD) &&
1510  "Did not find the overridden method!");
1511  MethodInfo &OverriddenMethodInfo = MethodInfoMap[OverriddenMD];
1512 
1513  MethodInfo MethodInfo(Base.getBaseOffset(), BaseOffsetInLayoutClass,
1514  OverriddenMethodInfo.VTableIndex);
1515 
1516  assert(!MethodInfoMap.count(MD) &&
1517  "Should not have method info for this method yet!");
1518 
1519  MethodInfoMap.insert(std::make_pair(MD, MethodInfo));
1520  MethodInfoMap.erase(OverriddenMD);
1521 
1522  // If the overridden method exists in a virtual base class or a direct
1523  // or indirect base class of a virtual base class, we need to emit a
1524  // thunk if we ever have a class hierarchy where the base class is not
1525  // a primary base in the complete object.
1526  if (!isBuildingConstructorVTable() && OverriddenMD != MD) {
1527  // Compute the this adjustment.
1529  ComputeThisAdjustment(OverriddenMD, BaseOffsetInLayoutClass,
1530  Overrider);
1531 
1532  if (ThisAdjustment.Virtual.Itanium.VCallOffsetOffset &&
1533  Overrider.Method->getParent() == MostDerivedClass) {
1534 
1535  // There's no return adjustment from OverriddenMD and MD,
1536  // but that doesn't mean there isn't one between MD and
1537  // the final overrider.
1538  BaseOffset ReturnAdjustmentOffset =
1539  ComputeReturnAdjustmentBaseOffset(Context, Overrider.Method, MD);
1540  ReturnAdjustment ReturnAdjustment =
1541  ComputeReturnAdjustment(ReturnAdjustmentOffset);
1542 
1543  // This is a virtual thunk for the most derived class, add it.
1544  AddThunk(Overrider.Method,
1545  ThunkInfo(ThisAdjustment, ReturnAdjustment));
1546  }
1547  }
1548 
1549  continue;
1550  }
1551  }
1552 
1553  if (MD->isImplicit())
1554  NewImplicitVirtualFunctions.push_back(MD);
1555  else
1556  NewVirtualFunctions.push_back(MD);
1557  }
1558 
1559  std::stable_sort(
1560  NewImplicitVirtualFunctions.begin(), NewImplicitVirtualFunctions.end(),
1561  [](const CXXMethodDecl *A, const CXXMethodDecl *B) {
1562  if (A->isCopyAssignmentOperator() != B->isCopyAssignmentOperator())
1563  return A->isCopyAssignmentOperator();
1564  if (A->isMoveAssignmentOperator() != B->isMoveAssignmentOperator())
1565  return A->isMoveAssignmentOperator();
1566  if (isa<CXXDestructorDecl>(A) != isa<CXXDestructorDecl>(B))
1567  return isa<CXXDestructorDecl>(A);
1568  assert(A->getOverloadedOperator() == OO_EqualEqual &&
1569  B->getOverloadedOperator() == OO_EqualEqual &&
1570  "unexpected or duplicate implicit virtual function");
1571  // We rely on Sema to have declared the operator== members in the
1572  // same order as the corresponding operator<=> members.
1573  return false;
1574  });
1575  NewVirtualFunctions.append(NewImplicitVirtualFunctions.begin(),
1576  NewImplicitVirtualFunctions.end());
1577 
1578  for (const CXXMethodDecl *MD : NewVirtualFunctions) {
1579  // Get the final overrider.
1580  FinalOverriders::OverriderInfo Overrider =
1581  Overriders.getOverrider(MD, Base.getBaseOffset());
1582 
1583  // Insert the method info for this method.
1584  MethodInfo MethodInfo(Base.getBaseOffset(), BaseOffsetInLayoutClass,
1585  Components.size());
1586 
1587  assert(!MethodInfoMap.count(MD) &&
1588  "Should not have method info for this method yet!");
1589  MethodInfoMap.insert(std::make_pair(MD, MethodInfo));
1590 
1591  // Check if this overrider is going to be used.
1592  const CXXMethodDecl *OverriderMD = Overrider.Method;
1593  if (!IsOverriderUsed(OverriderMD, BaseOffsetInLayoutClass,
1594  FirstBaseInPrimaryBaseChain,
1595  FirstBaseOffsetInLayoutClass)) {
1596  Components.push_back(VTableComponent::MakeUnusedFunction(OverriderMD));
1597  continue;
1598  }
1599 
1600  // Check if this overrider needs a return adjustment.
1601  // We don't want to do this for pure virtual member functions.
1602  BaseOffset ReturnAdjustmentOffset;
1603  if (!OverriderMD->isPure()) {
1604  ReturnAdjustmentOffset =
1605  ComputeReturnAdjustmentBaseOffset(Context, OverriderMD, MD);
1606  }
1607 
1608  ReturnAdjustment ReturnAdjustment =
1609  ComputeReturnAdjustment(ReturnAdjustmentOffset);
1610 
1611  AddMethod(Overrider.Method, ReturnAdjustment);
1612  }
1613 }
1614 
1615 void ItaniumVTableBuilder::LayoutVTable() {
1616  LayoutPrimaryAndSecondaryVTables(BaseSubobject(MostDerivedClass,
1617  CharUnits::Zero()),
1618  /*BaseIsMorallyVirtual=*/false,
1619  MostDerivedClassIsVirtual,
1620  MostDerivedClassOffset);
1621 
1622  VisitedVirtualBasesSetTy VBases;
1623 
1624  // Determine the primary virtual bases.
1625  DeterminePrimaryVirtualBases(MostDerivedClass, MostDerivedClassOffset,
1626  VBases);
1627  VBases.clear();
1628 
1629  LayoutVTablesForVirtualBases(MostDerivedClass, VBases);
1630 
1631  // -fapple-kext adds an extra entry at end of vtbl.
1632  bool IsAppleKext = Context.getLangOpts().AppleKext;
1633  if (IsAppleKext)
1634  Components.push_back(VTableComponent::MakeVCallOffset(CharUnits::Zero()));
1635 }
1636 
1637 void ItaniumVTableBuilder::LayoutPrimaryAndSecondaryVTables(
1638  BaseSubobject Base, bool BaseIsMorallyVirtual,
1639  bool BaseIsVirtualInLayoutClass, CharUnits OffsetInLayoutClass) {
1640  assert(Base.getBase()->isDynamicClass() && "class does not have a vtable!");
1641 
1642  unsigned VTableIndex = Components.size();
1643  VTableIndices.push_back(VTableIndex);
1644 
1645  // Add vcall and vbase offsets for this vtable.
1646  VCallAndVBaseOffsetBuilder Builder(
1647  VTables, MostDerivedClass, LayoutClass, &Overriders, Base,
1648  BaseIsVirtualInLayoutClass, OffsetInLayoutClass);
1649  Components.append(Builder.components_begin(), Builder.components_end());
1650 
1651  // Check if we need to add these vcall offsets.
1652  if (BaseIsVirtualInLayoutClass && !Builder.getVCallOffsets().empty()) {
1653  VCallOffsetMap &VCallOffsets = VCallOffsetsForVBases[Base.getBase()];
1654 
1655  if (VCallOffsets.empty())
1656  VCallOffsets = Builder.getVCallOffsets();
1657  }
1658 
1659  // If we're laying out the most derived class we want to keep track of the
1660  // virtual base class offset offsets.
1661  if (Base.getBase() == MostDerivedClass)
1662  VBaseOffsetOffsets = Builder.getVBaseOffsetOffsets();
1663 
1664  // Add the offset to top.
1665  CharUnits OffsetToTop = MostDerivedClassOffset - OffsetInLayoutClass;
1666  Components.push_back(VTableComponent::MakeOffsetToTop(OffsetToTop));
1667 
1668  // Next, add the RTTI.
1669  Components.push_back(VTableComponent::MakeRTTI(MostDerivedClass));
1670 
1671  uint64_t AddressPoint = Components.size();
1672 
1673  // Now go through all virtual member functions and add them.
1674  PrimaryBasesSetVectorTy PrimaryBases;
1675  AddMethods(Base, OffsetInLayoutClass,
1676  Base.getBase(), OffsetInLayoutClass,
1677  PrimaryBases);
1678 
1679  const CXXRecordDecl *RD = Base.getBase();
1680  if (RD == MostDerivedClass) {
1681  assert(MethodVTableIndices.empty());
1682  for (const auto &I : MethodInfoMap) {
1683  const CXXMethodDecl *MD = I.first;
1684  const MethodInfo &MI = I.second;
1685  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1686  MethodVTableIndices[GlobalDecl(DD, Dtor_Complete)]
1687  = MI.VTableIndex - AddressPoint;
1688  MethodVTableIndices[GlobalDecl(DD, Dtor_Deleting)]
1689  = MI.VTableIndex + 1 - AddressPoint;
1690  } else {
1691  MethodVTableIndices[MD] = MI.VTableIndex - AddressPoint;
1692  }
1693  }
1694  }
1695 
1696  // Compute 'this' pointer adjustments.
1697  ComputeThisAdjustments();
1698 
1699  // Add all address points.
1700  while (true) {
1701  AddressPoints.insert(
1702  std::make_pair(BaseSubobject(RD, OffsetInLayoutClass),
1704  unsigned(VTableIndices.size() - 1),
1705  unsigned(AddressPoint - VTableIndex)}));
1706 
1707  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1708  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
1709 
1710  if (!PrimaryBase)
1711  break;
1712 
1713  if (Layout.isPrimaryBaseVirtual()) {
1714  // Check if this virtual primary base is a primary base in the layout
1715  // class. If it's not, we don't want to add it.
1716  const ASTRecordLayout &LayoutClassLayout =
1717  Context.getASTRecordLayout(LayoutClass);
1718 
1719  if (LayoutClassLayout.getVBaseClassOffset(PrimaryBase) !=
1720  OffsetInLayoutClass) {
1721  // We don't want to add this class (or any of its primary bases).
1722  break;
1723  }
1724  }
1725 
1726  RD = PrimaryBase;
1727  }
1728 
1729  // Layout secondary vtables.
1730  LayoutSecondaryVTables(Base, BaseIsMorallyVirtual, OffsetInLayoutClass);
1731 }
1732 
1733 void
1734 ItaniumVTableBuilder::LayoutSecondaryVTables(BaseSubobject Base,
1735  bool BaseIsMorallyVirtual,
1736  CharUnits OffsetInLayoutClass) {
1737  // Itanium C++ ABI 2.5.2:
1738  // Following the primary virtual table of a derived class are secondary
1739  // virtual tables for each of its proper base classes, except any primary
1740  // base(s) with which it shares its primary virtual table.
1741 
1742  const CXXRecordDecl *RD = Base.getBase();
1743  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1744  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
1745 
1746  for (const auto &B : RD->bases()) {
1747  // Ignore virtual bases, we'll emit them later.
1748  if (B.isVirtual())
1749  continue;
1750 
1751  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
1752 
1753  // Ignore bases that don't have a vtable.
1754  if (!BaseDecl->isDynamicClass())
1755  continue;
1756 
1757  if (isBuildingConstructorVTable()) {
1758  // Itanium C++ ABI 2.6.4:
1759  // Some of the base class subobjects may not need construction virtual
1760  // tables, which will therefore not be present in the construction
1761  // virtual table group, even though the subobject virtual tables are
1762  // present in the main virtual table group for the complete object.
1763  if (!BaseIsMorallyVirtual && !BaseDecl->getNumVBases())
1764  continue;
1765  }
1766 
1767  // Get the base offset of this base.
1768  CharUnits RelativeBaseOffset = Layout.getBaseClassOffset(BaseDecl);
1769  CharUnits BaseOffset = Base.getBaseOffset() + RelativeBaseOffset;
1770 
1771  CharUnits BaseOffsetInLayoutClass =
1772  OffsetInLayoutClass + RelativeBaseOffset;
1773 
1774  // Don't emit a secondary vtable for a primary base. We might however want
1775  // to emit secondary vtables for other bases of this base.
1776  if (BaseDecl == PrimaryBase) {
1777  LayoutSecondaryVTables(BaseSubobject(BaseDecl, BaseOffset),
1778  BaseIsMorallyVirtual, BaseOffsetInLayoutClass);
1779  continue;
1780  }
1781 
1782  // Layout the primary vtable (and any secondary vtables) for this base.
1783  LayoutPrimaryAndSecondaryVTables(
1784  BaseSubobject(BaseDecl, BaseOffset),
1785  BaseIsMorallyVirtual,
1786  /*BaseIsVirtualInLayoutClass=*/false,
1787  BaseOffsetInLayoutClass);
1788  }
1789 }
1790 
1791 void ItaniumVTableBuilder::DeterminePrimaryVirtualBases(
1792  const CXXRecordDecl *RD, CharUnits OffsetInLayoutClass,
1793  VisitedVirtualBasesSetTy &VBases) {
1794  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1795 
1796  // Check if this base has a primary base.
1797  if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
1798 
1799  // Check if it's virtual.
1800  if (Layout.isPrimaryBaseVirtual()) {
1801  bool IsPrimaryVirtualBase = true;
1802 
1803  if (isBuildingConstructorVTable()) {
1804  // Check if the base is actually a primary base in the class we use for
1805  // layout.
1806  const ASTRecordLayout &LayoutClassLayout =
1807  Context.getASTRecordLayout(LayoutClass);
1808 
1809  CharUnits PrimaryBaseOffsetInLayoutClass =
1810  LayoutClassLayout.getVBaseClassOffset(PrimaryBase);
1811 
1812  // We know that the base is not a primary base in the layout class if
1813  // the base offsets are different.
1814  if (PrimaryBaseOffsetInLayoutClass != OffsetInLayoutClass)
1815  IsPrimaryVirtualBase = false;
1816  }
1817 
1818  if (IsPrimaryVirtualBase)
1819  PrimaryVirtualBases.insert(PrimaryBase);
1820  }
1821  }
1822 
1823  // Traverse bases, looking for more primary virtual bases.
1824  for (const auto &B : RD->bases()) {
1825  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
1826 
1827  CharUnits BaseOffsetInLayoutClass;
1828 
1829  if (B.isVirtual()) {
1830  if (!VBases.insert(BaseDecl).second)
1831  continue;
1832 
1833  const ASTRecordLayout &LayoutClassLayout =
1834  Context.getASTRecordLayout(LayoutClass);
1835 
1836  BaseOffsetInLayoutClass =
1837  LayoutClassLayout.getVBaseClassOffset(BaseDecl);
1838  } else {
1839  BaseOffsetInLayoutClass =
1840  OffsetInLayoutClass + Layout.getBaseClassOffset(BaseDecl);
1841  }
1842 
1843  DeterminePrimaryVirtualBases(BaseDecl, BaseOffsetInLayoutClass, VBases);
1844  }
1845 }
1846 
1847 void ItaniumVTableBuilder::LayoutVTablesForVirtualBases(
1848  const CXXRecordDecl *RD, VisitedVirtualBasesSetTy &VBases) {
1849  // Itanium C++ ABI 2.5.2:
1850  // Then come the virtual base virtual tables, also in inheritance graph
1851  // order, and again excluding primary bases (which share virtual tables with
1852  // the classes for which they are primary).
1853  for (const auto &B : RD->bases()) {
1854  const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
1855 
1856  // Check if this base needs a vtable. (If it's virtual, not a primary base
1857  // of some other class, and we haven't visited it before).
1858  if (B.isVirtual() && BaseDecl->isDynamicClass() &&
1859  !PrimaryVirtualBases.count(BaseDecl) &&
1860  VBases.insert(BaseDecl).second) {
1861  const ASTRecordLayout &MostDerivedClassLayout =
1862  Context.getASTRecordLayout(MostDerivedClass);
1863  CharUnits BaseOffset =
1864  MostDerivedClassLayout.getVBaseClassOffset(BaseDecl);
1865 
1866  const ASTRecordLayout &LayoutClassLayout =
1867  Context.getASTRecordLayout(LayoutClass);
1868  CharUnits BaseOffsetInLayoutClass =
1869  LayoutClassLayout.getVBaseClassOffset(BaseDecl);
1870 
1871  LayoutPrimaryAndSecondaryVTables(
1872  BaseSubobject(BaseDecl, BaseOffset),
1873  /*BaseIsMorallyVirtual=*/true,
1874  /*BaseIsVirtualInLayoutClass=*/true,
1875  BaseOffsetInLayoutClass);
1876  }
1877 
1878  // We only need to check the base for virtual base vtables if it actually
1879  // has virtual bases.
1880  if (BaseDecl->getNumVBases())
1881  LayoutVTablesForVirtualBases(BaseDecl, VBases);
1882  }
1883 }
1884 
1885 /// dumpLayout - Dump the vtable layout.
1886 void ItaniumVTableBuilder::dumpLayout(raw_ostream &Out) {
1887  // FIXME: write more tests that actually use the dumpLayout output to prevent
1888  // ItaniumVTableBuilder regressions.
1889 
1890  if (isBuildingConstructorVTable()) {
1891  Out << "Construction vtable for ('";
1892  MostDerivedClass->printQualifiedName(Out);
1893  Out << "', ";
1894  Out << MostDerivedClassOffset.getQuantity() << ") in '";
1895  LayoutClass->printQualifiedName(Out);
1896  } else {
1897  Out << "Vtable for '";
1898  MostDerivedClass->printQualifiedName(Out);
1899  }
1900  Out << "' (" << Components.size() << " entries).\n";
1901 
1902  // Iterate through the address points and insert them into a new map where
1903  // they are keyed by the index and not the base object.
1904  // Since an address point can be shared by multiple subobjects, we use an
1905  // STL multimap.
1906  std::multimap<uint64_t, BaseSubobject> AddressPointsByIndex;
1907  for (const auto &AP : AddressPoints) {
1908  const BaseSubobject &Base = AP.first;
1909  uint64_t Index =
1910  VTableIndices[AP.second.VTableIndex] + AP.second.AddressPointIndex;
1911 
1912  AddressPointsByIndex.insert(std::make_pair(Index, Base));
1913  }
1914 
1915  for (unsigned I = 0, E = Components.size(); I != E; ++I) {
1916  uint64_t Index = I;
1917 
1918  Out << llvm::format("%4d | ", I);
1919 
1920  const VTableComponent &Component = Components[I];
1921 
1922  // Dump the component.
1923  switch (Component.getKind()) {
1924 
1926  Out << "vcall_offset ("
1927  << Component.getVCallOffset().getQuantity()
1928  << ")";
1929  break;
1930 
1932  Out << "vbase_offset ("
1933  << Component.getVBaseOffset().getQuantity()
1934  << ")";
1935  break;
1936 
1938  Out << "offset_to_top ("
1939  << Component.getOffsetToTop().getQuantity()
1940  << ")";
1941  break;
1942 
1944  Component.getRTTIDecl()->printQualifiedName(Out);
1945  Out << " RTTI";
1946  break;
1947 
1949  const CXXMethodDecl *MD = Component.getFunctionDecl();
1950 
1951  std::string Str =
1953  MD);
1954  Out << Str;
1955  if (MD->isPure())
1956  Out << " [pure]";
1957 
1958  if (MD->isDeleted())
1959  Out << " [deleted]";
1960 
1961  ThunkInfo Thunk = VTableThunks.lookup(I);
1962  if (!Thunk.isEmpty()) {
1963  // If this function pointer has a return adjustment, dump it.
1964  if (!Thunk.Return.isEmpty()) {
1965  Out << "\n [return adjustment: ";
1966  Out << Thunk.Return.NonVirtual << " non-virtual";
1967 
1969  Out << ", " << Thunk.Return.Virtual.Itanium.VBaseOffsetOffset;
1970  Out << " vbase offset offset";
1971  }
1972 
1973  Out << ']';
1974  }
1975 
1976  // If this function pointer has a 'this' pointer adjustment, dump it.
1977  if (!Thunk.This.isEmpty()) {
1978  Out << "\n [this adjustment: ";
1979  Out << Thunk.This.NonVirtual << " non-virtual";
1980 
1981  if (Thunk.This.Virtual.Itanium.VCallOffsetOffset) {
1982  Out << ", " << Thunk.This.Virtual.Itanium.VCallOffsetOffset;
1983  Out << " vcall offset offset";
1984  }
1985 
1986  Out << ']';
1987  }
1988  }
1989 
1990  break;
1991  }
1992 
1995  bool IsComplete =
1997 
1998  const CXXDestructorDecl *DD = Component.getDestructorDecl();
1999 
2000  DD->printQualifiedName(Out);
2001  if (IsComplete)
2002  Out << "() [complete]";
2003  else
2004  Out << "() [deleting]";
2005 
2006  if (DD->isPure())
2007  Out << " [pure]";
2008 
2009  ThunkInfo Thunk = VTableThunks.lookup(I);
2010  if (!Thunk.isEmpty()) {
2011  // If this destructor has a 'this' pointer adjustment, dump it.
2012  if (!Thunk.This.isEmpty()) {
2013  Out << "\n [this adjustment: ";
2014  Out << Thunk.This.NonVirtual << " non-virtual";
2015 
2016  if (Thunk.This.Virtual.Itanium.VCallOffsetOffset) {
2017  Out << ", " << Thunk.This.Virtual.Itanium.VCallOffsetOffset;
2018  Out << " vcall offset offset";
2019  }
2020 
2021  Out << ']';
2022  }
2023  }
2024 
2025  break;
2026  }
2027 
2029  const CXXMethodDecl *MD = Component.getUnusedFunctionDecl();
2030 
2031  std::string Str =
2033  MD);
2034  Out << "[unused] " << Str;
2035  if (MD->isPure())
2036  Out << " [pure]";
2037  }
2038 
2039  }
2040 
2041  Out << '\n';
2042 
2043  // Dump the next address point.
2044  uint64_t NextIndex = Index + 1;
2045  if (AddressPointsByIndex.count(NextIndex)) {
2046  if (AddressPointsByIndex.count(NextIndex) == 1) {
2047  const BaseSubobject &Base =
2048  AddressPointsByIndex.find(NextIndex)->second;
2049 
2050  Out << " -- (";
2051  Base.getBase()->printQualifiedName(Out);
2052  Out << ", " << Base.getBaseOffset().getQuantity();
2053  Out << ") vtable address --\n";
2054  } else {
2055  CharUnits BaseOffset =
2056  AddressPointsByIndex.lower_bound(NextIndex)->second.getBaseOffset();
2057 
2058  // We store the class names in a set to get a stable order.
2059  std::set<std::string> ClassNames;
2060  for (const auto &I :
2061  llvm::make_range(AddressPointsByIndex.equal_range(NextIndex))) {
2062  assert(I.second.getBaseOffset() == BaseOffset &&
2063  "Invalid base offset!");
2064  const CXXRecordDecl *RD = I.second.getBase();
2065  ClassNames.insert(RD->getQualifiedNameAsString());
2066  }
2067 
2068  for (const std::string &Name : ClassNames) {
2069  Out << " -- (" << Name;
2070  Out << ", " << BaseOffset.getQuantity() << ") vtable address --\n";
2071  }
2072  }
2073  }
2074  }
2075 
2076  Out << '\n';
2077 
2078  if (isBuildingConstructorVTable())
2079  return;
2080 
2081  if (MostDerivedClass->getNumVBases()) {
2082  // We store the virtual base class names and their offsets in a map to get
2083  // a stable order.
2084 
2085  std::map<std::string, CharUnits> ClassNamesAndOffsets;
2086  for (const auto &I : VBaseOffsetOffsets) {
2087  std::string ClassName = I.first->getQualifiedNameAsString();
2088  CharUnits OffsetOffset = I.second;
2089  ClassNamesAndOffsets.insert(std::make_pair(ClassName, OffsetOffset));
2090  }
2091 
2092  Out << "Virtual base offset offsets for '";
2093  MostDerivedClass->printQualifiedName(Out);
2094  Out << "' (";
2095  Out << ClassNamesAndOffsets.size();
2096  Out << (ClassNamesAndOffsets.size() == 1 ? " entry" : " entries") << ").\n";
2097 
2098  for (const auto &I : ClassNamesAndOffsets)
2099  Out << " " << I.first << " | " << I.second.getQuantity() << '\n';
2100 
2101  Out << "\n";
2102  }
2103 
2104  if (!Thunks.empty()) {
2105  // We store the method names in a map to get a stable order.
2106  std::map<std::string, const CXXMethodDecl *> MethodNamesAndDecls;
2107 
2108  for (const auto &I : Thunks) {
2109  const CXXMethodDecl *MD = I.first;
2110  std::string MethodName =
2112  MD);
2113 
2114  MethodNamesAndDecls.insert(std::make_pair(MethodName, MD));
2115  }
2116 
2117  for (const auto &I : MethodNamesAndDecls) {
2118  const std::string &MethodName = I.first;
2119  const CXXMethodDecl *MD = I.second;
2120 
2121  ThunkInfoVectorTy ThunksVector = Thunks[MD];
2122  llvm::sort(ThunksVector, [](const ThunkInfo &LHS, const ThunkInfo &RHS) {
2123  assert(LHS.Method == nullptr && RHS.Method == nullptr);
2124  return std::tie(LHS.This, LHS.Return) < std::tie(RHS.This, RHS.Return);
2125  });
2126 
2127  Out << "Thunks for '" << MethodName << "' (" << ThunksVector.size();
2128  Out << (ThunksVector.size() == 1 ? " entry" : " entries") << ").\n";
2129 
2130  for (unsigned I = 0, E = ThunksVector.size(); I != E; ++I) {
2131  const ThunkInfo &Thunk = ThunksVector[I];
2132 
2133  Out << llvm::format("%4d | ", I);
2134 
2135  // If this function pointer has a return pointer adjustment, dump it.
2136  if (!Thunk.Return.isEmpty()) {
2137  Out << "return adjustment: " << Thunk.Return.NonVirtual;
2138  Out << " non-virtual";
2140  Out << ", " << Thunk.Return.Virtual.Itanium.VBaseOffsetOffset;
2141  Out << " vbase offset offset";
2142  }
2143 
2144  if (!Thunk.This.isEmpty())
2145  Out << "\n ";
2146  }
2147 
2148  // If this function pointer has a 'this' pointer adjustment, dump it.
2149  if (!Thunk.This.isEmpty()) {
2150  Out << "this adjustment: ";
2151  Out << Thunk.This.NonVirtual << " non-virtual";
2152 
2153  if (Thunk.This.Virtual.Itanium.VCallOffsetOffset) {
2154  Out << ", " << Thunk.This.Virtual.Itanium.VCallOffsetOffset;
2155  Out << " vcall offset offset";
2156  }
2157  }
2158 
2159  Out << '\n';
2160  }
2161 
2162  Out << '\n';
2163  }
2164  }
2165 
2166  // Compute the vtable indices for all the member functions.
2167  // Store them in a map keyed by the index so we'll get a sorted table.
2168  std::map<uint64_t, std::string> IndicesMap;
2169 
2170  for (const auto *MD : MostDerivedClass->methods()) {
2171  // We only want virtual member functions.
2173  continue;
2174  MD = MD->getCanonicalDecl();
2175 
2176  std::string MethodName =
2178  MD);
2179 
2180  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
2181  GlobalDecl GD(DD, Dtor_Complete);
2182  assert(MethodVTableIndices.count(GD));
2183  uint64_t VTableIndex = MethodVTableIndices[GD];
2184  IndicesMap[VTableIndex] = MethodName + " [complete]";
2185  IndicesMap[VTableIndex + 1] = MethodName + " [deleting]";
2186  } else {
2187  assert(MethodVTableIndices.count(MD));
2188  IndicesMap[MethodVTableIndices[MD]] = MethodName;
2189  }
2190  }
2191 
2192  // Print the vtable indices for all the member functions.
2193  if (!IndicesMap.empty()) {
2194  Out << "VTable indices for '";
2195  MostDerivedClass->printQualifiedName(Out);
2196  Out << "' (" << IndicesMap.size() << " entries).\n";
2197 
2198  for (const auto &I : IndicesMap) {
2199  uint64_t VTableIndex = I.first;
2200  const std::string &MethodName = I.second;
2201 
2202  Out << llvm::format("%4" PRIu64 " | ", VTableIndex) << MethodName
2203  << '\n';
2204  }
2205  }
2206 
2207  Out << '\n';
2208 }
2209 }
2210 
2213  unsigned numVTables) {
2214  VTableLayout::AddressPointsIndexMapTy indexMap(numVTables);
2215 
2216  for (auto it = addressPoints.begin(); it != addressPoints.end(); ++it) {
2217  const auto &addressPointLoc = it->second;
2218  unsigned vtableIndex = addressPointLoc.VTableIndex;
2219  unsigned addressPoint = addressPointLoc.AddressPointIndex;
2220  if (indexMap[vtableIndex]) {
2221  // Multiple BaseSubobjects can map to the same AddressPointLocation, but
2222  // every vtable index should have a unique address point.
2223  assert(indexMap[vtableIndex] == addressPoint &&
2224  "Every vtable index should have a unique address point. Found a "
2225  "vtable that has two different address points.");
2226  } else {
2227  indexMap[vtableIndex] = addressPoint;
2228  }
2229  }
2230 
2231  // Note that by this point, not all the address may be initialized if the
2232  // AddressPoints map is empty. This is ok if the map isn't needed. See
2233  // MicrosoftVTableContext::computeVTableRelatedInformation() which uses an
2234  // emprt map.
2235  return indexMap;
2236 }
2237 
2239  ArrayRef<VTableComponent> VTableComponents,
2240  ArrayRef<VTableThunkTy> VTableThunks,
2241  const AddressPointsMapTy &AddressPoints)
2242  : VTableComponents(VTableComponents), VTableThunks(VTableThunks),
2243  AddressPoints(AddressPoints), AddressPointIndices(MakeAddressPointIndices(
2244  AddressPoints, VTableIndices.size())) {
2245  if (VTableIndices.size() <= 1)
2246  assert(VTableIndices.size() == 1 && VTableIndices[0] == 0);
2247  else
2248  this->VTableIndices = OwningArrayRef<size_t>(VTableIndices);
2249 
2250  llvm::sort(this->VTableThunks, [](const VTableLayout::VTableThunkTy &LHS,
2251  const VTableLayout::VTableThunkTy &RHS) {
2252  assert((LHS.first != RHS.first || LHS.second == RHS.second) &&
2253  "Different thunks should have unique indices!");
2254  return LHS.first < RHS.first;
2255  });
2256 }
2257 
2259 
2261  return MD->isVirtual() && !MD->isConsteval();
2262 }
2263 
2265  ASTContext &Context, VTableComponentLayout ComponentLayout)
2266  : VTableContextBase(/*MS=*/false), ComponentLayout(ComponentLayout) {}
2267 
2269 
2271  GD = GD.getCanonicalDecl();
2272  MethodVTableIndicesTy::iterator I = MethodVTableIndices.find(GD);
2273  if (I != MethodVTableIndices.end())
2274  return I->second;
2275 
2276  const CXXRecordDecl *RD = cast<CXXMethodDecl>(GD.getDecl())->getParent();
2277 
2278  computeVTableRelatedInformation(RD);
2279 
2280  I = MethodVTableIndices.find(GD);
2281  assert(I != MethodVTableIndices.end() && "Did not find index!");
2282  return I->second;
2283 }
2284 
2285 CharUnits
2287  const CXXRecordDecl *VBase) {
2288  ClassPairTy ClassPair(RD, VBase);
2289 
2290  VirtualBaseClassOffsetOffsetsMapTy::iterator I =
2291  VirtualBaseClassOffsetOffsets.find(ClassPair);
2292  if (I != VirtualBaseClassOffsetOffsets.end())
2293  return I->second;
2294 
2295  VCallAndVBaseOffsetBuilder Builder(*this, RD, RD, /*Overriders=*/nullptr,
2297  /*BaseIsVirtual=*/false,
2298  /*OffsetInLayoutClass=*/CharUnits::Zero());
2299 
2300  for (const auto &I : Builder.getVBaseOffsetOffsets()) {
2301  // Insert all types.
2302  ClassPairTy ClassPair(RD, I.first);
2303 
2304  VirtualBaseClassOffsetOffsets.insert(std::make_pair(ClassPair, I.second));
2305  }
2306 
2307  I = VirtualBaseClassOffsetOffsets.find(ClassPair);
2308  assert(I != VirtualBaseClassOffsetOffsets.end() && "Did not find index!");
2309 
2310  return I->second;
2311 }
2312 
2313 static std::unique_ptr<VTableLayout>
2314 CreateVTableLayout(const ItaniumVTableBuilder &Builder) {
2316  VTableThunks(Builder.vtable_thunks_begin(), Builder.vtable_thunks_end());
2317 
2318  return std::make_unique<VTableLayout>(
2319  Builder.VTableIndices, Builder.vtable_components(), VTableThunks,
2320  Builder.getAddressPoints());
2321 }
2322 
2323 void
2324 ItaniumVTableContext::computeVTableRelatedInformation(const CXXRecordDecl *RD) {
2325  std::unique_ptr<const VTableLayout> &Entry = VTableLayouts[RD];
2326 
2327  // Check if we've computed this information before.
2328  if (Entry)
2329  return;
2330 
2331  ItaniumVTableBuilder Builder(*this, RD, CharUnits::Zero(),
2332  /*MostDerivedClassIsVirtual=*/0, RD);
2333  Entry = CreateVTableLayout(Builder);
2334 
2335  MethodVTableIndices.insert(Builder.vtable_indices_begin(),
2336  Builder.vtable_indices_end());
2337 
2338  // Add the known thunks.
2339  Thunks.insert(Builder.thunks_begin(), Builder.thunks_end());
2340 
2341  // If we don't have the vbase information for this class, insert it.
2342  // getVirtualBaseOffsetOffset will compute it separately without computing
2343  // the rest of the vtable related information.
2344  if (!RD->getNumVBases())
2345  return;
2346 
2347  const CXXRecordDecl *VBase =
2349 
2350  if (VirtualBaseClassOffsetOffsets.count(std::make_pair(RD, VBase)))
2351  return;
2352 
2353  for (const auto &I : Builder.getVBaseOffsetOffsets()) {
2354  // Insert all types.
2355  ClassPairTy ClassPair(RD, I.first);
2356 
2357  VirtualBaseClassOffsetOffsets.insert(std::make_pair(ClassPair, I.second));
2358  }
2359 }
2360 
2361 std::unique_ptr<VTableLayout>
2363  const CXXRecordDecl *MostDerivedClass, CharUnits MostDerivedClassOffset,
2364  bool MostDerivedClassIsVirtual, const CXXRecordDecl *LayoutClass) {
2365  ItaniumVTableBuilder Builder(*this, MostDerivedClass, MostDerivedClassOffset,
2366  MostDerivedClassIsVirtual, LayoutClass);
2367  return CreateVTableLayout(Builder);
2368 }
2369 
2370 namespace {
2371 
2372 // Vtables in the Microsoft ABI are different from the Itanium ABI.
2373 //
2374 // The main differences are:
2375 // 1. Separate vftable and vbtable.
2376 //
2377 // 2. Each subobject with a vfptr gets its own vftable rather than an address
2378 // point in a single vtable shared between all the subobjects.
2379 // Each vftable is represented by a separate section and virtual calls
2380 // must be done using the vftable which has a slot for the function to be
2381 // called.
2382 //
2383 // 3. Virtual method definitions expect their 'this' parameter to point to the
2384 // first vfptr whose table provides a compatible overridden method. In many
2385 // cases, this permits the original vf-table entry to directly call
2386 // the method instead of passing through a thunk.
2387 // See example before VFTableBuilder::ComputeThisOffset below.
2388 //
2389 // A compatible overridden method is one which does not have a non-trivial
2390 // covariant-return adjustment.
2391 //
2392 // The first vfptr is the one with the lowest offset in the complete-object
2393 // layout of the defining class, and the method definition will subtract
2394 // that constant offset from the parameter value to get the real 'this'
2395 // value. Therefore, if the offset isn't really constant (e.g. if a virtual
2396 // function defined in a virtual base is overridden in a more derived
2397 // virtual base and these bases have a reverse order in the complete
2398 // object), the vf-table may require a this-adjustment thunk.
2399 //
2400 // 4. vftables do not contain new entries for overrides that merely require
2401 // this-adjustment. Together with #3, this keeps vf-tables smaller and
2402 // eliminates the need for this-adjustment thunks in many cases, at the cost
2403 // of often requiring redundant work to adjust the "this" pointer.
2404 //
2405 // 5. Instead of VTT and constructor vtables, vbtables and vtordisps are used.
2406 // Vtordisps are emitted into the class layout if a class has
2407 // a) a user-defined ctor/dtor
2408 // and
2409 // b) a method overriding a method in a virtual base.
2410 //
2411 // To get a better understanding of this code,
2412 // you might want to see examples in test/CodeGenCXX/microsoft-abi-vtables-*.cpp
2413 
2414 class VFTableBuilder {
2415 public:
2416  typedef llvm::DenseMap<GlobalDecl, MethodVFTableLocation>
2417  MethodVFTableLocationsTy;
2418 
2419  typedef llvm::iterator_range<MethodVFTableLocationsTy::const_iterator>
2420  method_locations_range;
2421 
2422 private:
2423  /// VTables - Global vtable information.
2424  MicrosoftVTableContext &VTables;
2425 
2426  /// Context - The ASTContext which we will use for layout information.
2427  ASTContext &Context;
2428 
2429  /// MostDerivedClass - The most derived class for which we're building this
2430  /// vtable.
2431  const CXXRecordDecl *MostDerivedClass;
2432 
2433  const ASTRecordLayout &MostDerivedClassLayout;
2434 
2435  const VPtrInfo &WhichVFPtr;
2436 
2437  /// FinalOverriders - The final overriders of the most derived class.
2438  const FinalOverriders Overriders;
2439 
2440  /// Components - The components of the vftable being built.
2442 
2443  MethodVFTableLocationsTy MethodVFTableLocations;
2444 
2445  /// Does this class have an RTTI component?
2446  bool HasRTTIComponent = false;
2447 
2448  /// MethodInfo - Contains information about a method in a vtable.
2449  /// (Used for computing 'this' pointer adjustment thunks.
2450  struct MethodInfo {
2451  /// VBTableIndex - The nonzero index in the vbtable that
2452  /// this method's base has, or zero.
2453  const uint64_t VBTableIndex;
2454 
2455  /// VFTableIndex - The index in the vftable that this method has.
2456  const uint64_t VFTableIndex;
2457 
2458  /// Shadowed - Indicates if this vftable slot is shadowed by
2459  /// a slot for a covariant-return override. If so, it shouldn't be printed
2460  /// or used for vcalls in the most derived class.
2461  bool Shadowed;
2462 
2463  /// UsesExtraSlot - Indicates if this vftable slot was created because
2464  /// any of the overridden slots required a return adjusting thunk.
2465  bool UsesExtraSlot;
2466 
2467  MethodInfo(uint64_t VBTableIndex, uint64_t VFTableIndex,
2468  bool UsesExtraSlot = false)
2469  : VBTableIndex(VBTableIndex), VFTableIndex(VFTableIndex),
2470  Shadowed(false), UsesExtraSlot(UsesExtraSlot) {}
2471 
2472  MethodInfo()
2473  : VBTableIndex(0), VFTableIndex(0), Shadowed(false),
2474  UsesExtraSlot(false) {}
2475  };
2476 
2477  typedef llvm::DenseMap<const CXXMethodDecl *, MethodInfo> MethodInfoMapTy;
2478 
2479  /// MethodInfoMap - The information for all methods in the vftable we're
2480  /// currently building.
2481  MethodInfoMapTy MethodInfoMap;
2482 
2483  typedef llvm::DenseMap<uint64_t, ThunkInfo> VTableThunksMapTy;
2484 
2485  /// VTableThunks - The thunks by vftable index in the vftable currently being
2486  /// built.
2487  VTableThunksMapTy VTableThunks;
2488 
2490  typedef llvm::DenseMap<const CXXMethodDecl *, ThunkInfoVectorTy> ThunksMapTy;
2491 
2492  /// Thunks - A map that contains all the thunks needed for all methods in the
2493  /// most derived class for which the vftable is currently being built.
2494  ThunksMapTy Thunks;
2495 
2496  /// AddThunk - Add a thunk for the given method.
2497  void AddThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk) {
2498  SmallVector<ThunkInfo, 1> &ThunksVector = Thunks[MD];
2499 
2500  // Check if we have this thunk already.
2501  if (llvm::find(ThunksVector, Thunk) != ThunksVector.end())
2502  return;
2503 
2504  ThunksVector.push_back(Thunk);
2505  }
2506 
2507  /// ComputeThisOffset - Returns the 'this' argument offset for the given
2508  /// method, relative to the beginning of the MostDerivedClass.
2509  CharUnits ComputeThisOffset(FinalOverriders::OverriderInfo Overrider);
2510 
2511  void CalculateVtordispAdjustment(FinalOverriders::OverriderInfo Overrider,
2512  CharUnits ThisOffset, ThisAdjustment &TA);
2513 
2514  /// AddMethod - Add a single virtual member function to the vftable
2515  /// components vector.
2516  void AddMethod(const CXXMethodDecl *MD, ThunkInfo TI) {
2517  if (!TI.isEmpty()) {
2518  VTableThunks[Components.size()] = TI;
2519  AddThunk(MD, TI);
2520  }
2521  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
2522  assert(TI.Return.isEmpty() &&
2523  "Destructor can't have return adjustment!");
2524  Components.push_back(VTableComponent::MakeDeletingDtor(DD));
2525  } else {
2526  Components.push_back(VTableComponent::MakeFunction(MD));
2527  }
2528  }
2529 
2530  /// AddMethods - Add the methods of this base subobject and the relevant
2531  /// subbases to the vftable we're currently laying out.
2532  void AddMethods(BaseSubobject Base, unsigned BaseDepth,
2533  const CXXRecordDecl *LastVBase,
2534  BasesSetVectorTy &VisitedBases);
2535 
2536  void LayoutVFTable() {
2537  // RTTI data goes before all other entries.
2538  if (HasRTTIComponent)
2539  Components.push_back(VTableComponent::MakeRTTI(MostDerivedClass));
2540 
2541  BasesSetVectorTy VisitedBases;
2542  AddMethods(BaseSubobject(MostDerivedClass, CharUnits::Zero()), 0, nullptr,
2543  VisitedBases);
2544  // Note that it is possible for the vftable to contain only an RTTI
2545  // pointer, if all virtual functions are constewval.
2546  assert(!Components.empty() && "vftable can't be empty");
2547 
2548  assert(MethodVFTableLocations.empty());
2549  for (const auto &I : MethodInfoMap) {
2550  const CXXMethodDecl *MD = I.first;
2551  const MethodInfo &MI = I.second;
2552  assert(MD == MD->getCanonicalDecl());
2553 
2554  // Skip the methods that the MostDerivedClass didn't override
2555  // and the entries shadowed by return adjusting thunks.
2556  if (MD->getParent() != MostDerivedClass || MI.Shadowed)
2557  continue;
2558  MethodVFTableLocation Loc(MI.VBTableIndex, WhichVFPtr.getVBaseWithVPtr(),
2559  WhichVFPtr.NonVirtualOffset, MI.VFTableIndex);
2560  if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
2561  MethodVFTableLocations[GlobalDecl(DD, Dtor_Deleting)] = Loc;
2562  } else {
2563  MethodVFTableLocations[MD] = Loc;
2564  }
2565  }
2566  }
2567 
2568 public:
2569  VFTableBuilder(MicrosoftVTableContext &VTables,
2570  const CXXRecordDecl *MostDerivedClass, const VPtrInfo &Which)
2571  : VTables(VTables),
2572  Context(MostDerivedClass->getASTContext()),
2573  MostDerivedClass(MostDerivedClass),
2574  MostDerivedClassLayout(Context.getASTRecordLayout(MostDerivedClass)),
2575  WhichVFPtr(Which),
2576  Overriders(MostDerivedClass, CharUnits(), MostDerivedClass) {
2577  // Provide the RTTI component if RTTIData is enabled. If the vftable would
2578  // be available externally, we should not provide the RTTI componenent. It
2579  // is currently impossible to get available externally vftables with either
2580  // dllimport or extern template instantiations, but eventually we may add a
2581  // flag to support additional devirtualization that needs this.
2582  if (Context.getLangOpts().RTTIData)
2583  HasRTTIComponent = true;
2584 
2585  LayoutVFTable();
2586 
2587  if (Context.getLangOpts().DumpVTableLayouts)
2588  dumpLayout(llvm::outs());
2589  }
2590 
2591  uint64_t getNumThunks() const { return Thunks.size(); }
2592 
2593  ThunksMapTy::const_iterator thunks_begin() const { return Thunks.begin(); }
2594 
2595  ThunksMapTy::const_iterator thunks_end() const { return Thunks.end(); }
2596 
2597  method_locations_range vtable_locations() const {
2598  return method_locations_range(MethodVFTableLocations.begin(),
2599  MethodVFTableLocations.end());
2600  }
2601 
2602  ArrayRef<VTableComponent> vtable_components() const { return Components; }
2603 
2604  VTableThunksMapTy::const_iterator vtable_thunks_begin() const {
2605  return VTableThunks.begin();
2606  }
2607 
2608  VTableThunksMapTy::const_iterator vtable_thunks_end() const {
2609  return VTableThunks.end();
2610  }
2611 
2612  void dumpLayout(raw_ostream &);
2613 };
2614 
2615 } // end namespace
2616 
2617 // Let's study one class hierarchy as an example:
2618 // struct A {
2619 // virtual void f();
2620 // int x;
2621 // };
2622 //
2623 // struct B : virtual A {
2624 // virtual void f();
2625 // };
2626 //
2627 // Record layouts:
2628 // struct A:
2629 // 0 | (A vftable pointer)
2630 // 4 | int x
2631 //
2632 // struct B:
2633 // 0 | (B vbtable pointer)
2634 // 4 | struct A (virtual base)
2635 // 4 | (A vftable pointer)
2636 // 8 | int x
2637 //
2638 // Let's assume we have a pointer to the A part of an object of dynamic type B:
2639 // B b;
2640 // A *a = (A*)&b;
2641 // a->f();
2642 //
2643 // In this hierarchy, f() belongs to the vftable of A, so B::f() expects
2644 // "this" parameter to point at the A subobject, which is B+4.
2645 // In the B::f() prologue, it adjusts "this" back to B by subtracting 4,
2646 // performed as a *static* adjustment.
2647 //
2648 // Interesting thing happens when we alter the relative placement of A and B
2649 // subobjects in a class:
2650 // struct C : virtual B { };
2651 //
2652 // C c;
2653 // A *a = (A*)&c;
2654 // a->f();
2655 //
2656 // Respective record layout is:
2657 // 0 | (C vbtable pointer)
2658 // 4 | struct A (virtual base)
2659 // 4 | (A vftable pointer)
2660 // 8 | int x
2661 // 12 | struct B (virtual base)
2662 // 12 | (B vbtable pointer)
2663 //
2664 // The final overrider of f() in class C is still B::f(), so B+4 should be
2665 // passed as "this" to that code. However, "a" points at B-8, so the respective
2666 // vftable entry should hold a thunk that adds 12 to the "this" argument before
2667 // performing a tail call to B::f().
2668 //
2669 // With this example in mind, we can now calculate the 'this' argument offset
2670 // for the given method, relative to the beginning of the MostDerivedClass.
2671 CharUnits
2672 VFTableBuilder::ComputeThisOffset(FinalOverriders::OverriderInfo Overrider) {
2673  BasesSetVectorTy Bases;
2674 
2675  {
2676  // Find the set of least derived bases that define the given method.
2677  OverriddenMethodsSetTy VisitedOverriddenMethods;
2678  auto InitialOverriddenDefinitionCollector = [&](
2679  const CXXMethodDecl *OverriddenMD) {
2680  if (OverriddenMD->size_overridden_methods() == 0)
2681  Bases.insert(OverriddenMD->getParent());
2682  // Don't recurse on this method if we've already collected it.
2683  return VisitedOverriddenMethods.insert(OverriddenMD).second;
2684  };
2685  visitAllOverriddenMethods(Overrider.Method,
2686  InitialOverriddenDefinitionCollector);
2687  }
2688 
2689  // If there are no overrides then 'this' is located
2690  // in the base that defines the method.
2691  if (Bases.size() == 0)
2692  return Overrider.Offset;
2693 
2694  CXXBasePaths Paths;
2695  Overrider.Method->getParent()->lookupInBases(
2696  [&Bases](const CXXBaseSpecifier *Specifier, CXXBasePath &) {
2697  return Bases.count(Specifier->getType()->getAsCXXRecordDecl());
2698  },
2699  Paths);
2700 
2701  // This will hold the smallest this offset among overridees of MD.
2702  // This implies that an offset of a non-virtual base will dominate an offset
2703  // of a virtual base to potentially reduce the number of thunks required
2704  // in the derived classes that inherit this method.
2705  CharUnits Ret;
2706  bool First = true;
2707 
2708  const ASTRecordLayout &OverriderRDLayout =
2709  Context.getASTRecordLayout(Overrider.Method->getParent());
2710  for (const CXXBasePath &Path : Paths) {
2711  CharUnits ThisOffset = Overrider.Offset;
2712  CharUnits LastVBaseOffset;
2713 
2714  // For each path from the overrider to the parents of the overridden
2715  // methods, traverse the path, calculating the this offset in the most
2716  // derived class.
2717  for (const CXXBasePathElement &Element : Path) {
2718  QualType CurTy = Element.Base->getType();
2719  const CXXRecordDecl *PrevRD = Element.Class,
2720  *CurRD = CurTy->getAsCXXRecordDecl();
2721  const ASTRecordLayout &Layout = Context.getASTRecordLayout(PrevRD);
2722 
2723  if (Element.Base->isVirtual()) {
2724  // The interesting things begin when you have virtual inheritance.
2725  // The final overrider will use a static adjustment equal to the offset
2726  // of the vbase in the final overrider class.
2727  // For example, if the final overrider is in a vbase B of the most
2728  // derived class and it overrides a method of the B's own vbase A,
2729  // it uses A* as "this". In its prologue, it can cast A* to B* with
2730  // a static offset. This offset is used regardless of the actual
2731  // offset of A from B in the most derived class, requiring an
2732  // this-adjusting thunk in the vftable if A and B are laid out
2733  // differently in the most derived class.
2734  LastVBaseOffset = ThisOffset =
2735  Overrider.Offset + OverriderRDLayout.getVBaseClassOffset(CurRD);
2736  } else {
2737  ThisOffset += Layout.getBaseClassOffset(CurRD);
2738  }
2739  }
2740 
2741  if (isa<CXXDestructorDecl>(Overrider.Method)) {
2742  if (LastVBaseOffset.isZero()) {
2743  // If a "Base" class has at least one non-virtual base with a virtual
2744  // destructor, the "Base" virtual destructor will take the address
2745  // of the "Base" subobject as the "this" argument.
2746  ThisOffset = Overrider.Offset;
2747  } else {
2748  // A virtual destructor of a virtual base takes the address of the
2749  // virtual base subobject as the "this" argument.
2750  ThisOffset = LastVBaseOffset;
2751  }
2752  }
2753 
2754  if (Ret > ThisOffset || First) {
2755  First = false;
2756  Ret = ThisOffset;
2757  }
2758  }
2759 
2760  assert(!First && "Method not found in the given subobject?");
2761  return Ret;
2762 }
2763 
2764 // Things are getting even more complex when the "this" adjustment has to
2765 // use a dynamic offset instead of a static one, or even two dynamic offsets.
2766 // This is sometimes required when a virtual call happens in the middle of
2767 // a non-most-derived class construction or destruction.
2768 //
2769 // Let's take a look at the following example:
2770 // struct A {
2771 // virtual void f();
2772 // };
2773 //
2774 // void foo(A *a) { a->f(); } // Knows nothing about siblings of A.
2775 //
2776 // struct B : virtual A {
2777 // virtual void f();
2778 // B() {
2779 // foo(this);
2780 // }
2781 // };
2782 //
2783 // struct C : virtual B {
2784 // virtual void f();
2785 // };
2786 //
2787 // Record layouts for these classes are:
2788 // struct A
2789 // 0 | (A vftable pointer)
2790 //
2791 // struct B
2792 // 0 | (B vbtable pointer)
2793 // 4 | (vtordisp for vbase A)
2794 // 8 | struct A (virtual base)
2795 // 8 | (A vftable pointer)
2796 //
2797 // struct C
2798 // 0 | (C vbtable pointer)
2799 // 4 | (vtordisp for vbase A)
2800 // 8 | struct A (virtual base) // A precedes B!
2801 // 8 | (A vftable pointer)
2802 // 12 | struct B (virtual base)
2803 // 12 | (B vbtable pointer)
2804 //
2805 // When one creates an object of type C, the C constructor:
2806 // - initializes all the vbptrs, then
2807 // - calls the A subobject constructor
2808 // (initializes A's vfptr with an address of A vftable), then
2809 // - calls the B subobject constructor
2810 // (initializes A's vfptr with an address of B vftable and vtordisp for A),
2811 // that in turn calls foo(), then
2812 // - initializes A's vfptr with an address of C vftable and zeroes out the
2813 // vtordisp
2814 // FIXME: if a structor knows it belongs to MDC, why doesn't it use a vftable
2815 // without vtordisp thunks?
2816 // FIXME: how are vtordisp handled in the presence of nooverride/final?
2817 //
2818 // When foo() is called, an object with a layout of class C has a vftable
2819 // referencing B::f() that assumes a B layout, so the "this" adjustments are
2820 // incorrect, unless an extra adjustment is done. This adjustment is called
2821 // "vtordisp adjustment". Vtordisp basically holds the difference between the
2822 // actual location of a vbase in the layout class and the location assumed by
2823 // the vftable of the class being constructed/destructed. Vtordisp is only
2824 // needed if "this" escapes a
2825 // structor (or we can't prove otherwise).
2826 // [i.e. vtordisp is a dynamic adjustment for a static adjustment, which is an
2827 // estimation of a dynamic adjustment]
2828 //
2829 // foo() gets a pointer to the A vbase and doesn't know anything about B or C,
2830 // so it just passes that pointer as "this" in a virtual call.
2831 // If there was no vtordisp, that would just dispatch to B::f().
2832 // However, B::f() assumes B+8 is passed as "this",
2833 // yet the pointer foo() passes along is B-4 (i.e. C+8).
2834 // An extra adjustment is needed, so we emit a thunk into the B vftable.
2835 // This vtordisp thunk subtracts the value of vtordisp
2836 // from the "this" argument (-12) before making a tailcall to B::f().
2837 //
2838 // Let's consider an even more complex example:
2839 // struct D : virtual B, virtual C {
2840 // D() {
2841 // foo(this);
2842 // }
2843 // };
2844 //
2845 // struct D
2846 // 0 | (D vbtable pointer)
2847 // 4 | (vtordisp for vbase A)
2848 // 8 | struct A (virtual base) // A precedes both B and C!
2849 // 8 | (A vftable pointer)
2850 // 12 | struct B (virtual base) // B precedes C!
2851 // 12 | (B vbtable pointer)
2852 // 16 | struct C (virtual base)
2853 // 16 | (C vbtable pointer)
2854 //
2855 // When D::D() calls foo(), we find ourselves in a thunk that should tailcall
2856 // to C::f(), which assumes C+8 as its "this" parameter. This time, foo()
2857 // passes along A, which is C-8. The A vtordisp holds
2858 // "D.vbptr[index_of_A] - offset_of_A_in_D"
2859 // and we statically know offset_of_A_in_D, so can get a pointer to D.
2860 // When we know it, we can make an extra vbtable lookup to locate the C vbase
2861 // and one extra static adjustment to calculate the expected value of C+8.
2862 void VFTableBuilder::CalculateVtordispAdjustment(
2863  FinalOverriders::OverriderInfo Overrider, CharUnits ThisOffset,
2864  ThisAdjustment &TA) {
2865  const ASTRecordLayout::VBaseOffsetsMapTy &VBaseMap =
2866  MostDerivedClassLayout.getVBaseOffsetsMap();
2867  const ASTRecordLayout::VBaseOffsetsMapTy::const_iterator &VBaseMapEntry =
2868  VBaseMap.find(WhichVFPtr.getVBaseWithVPtr());
2869  assert(VBaseMapEntry != VBaseMap.end());
2870 
2871  // If there's no vtordisp or the final overrider is defined in the same vbase
2872  // as the initial declaration, we don't need any vtordisp adjustment.
2873  if (!VBaseMapEntry->second.hasVtorDisp() ||
2874  Overrider.VirtualBase == WhichVFPtr.getVBaseWithVPtr())
2875  return;
2876 
2877  // OK, now we know we need to use a vtordisp thunk.
2878  // The implicit vtordisp field is located right before the vbase.
2879  CharUnits OffsetOfVBaseWithVFPtr = VBaseMapEntry->second.VBaseOffset;
2881  (OffsetOfVBaseWithVFPtr - WhichVFPtr.FullOffsetInMDC).getQuantity() - 4;
2882 
2883  // A simple vtordisp thunk will suffice if the final overrider is defined
2884  // in either the most derived class or its non-virtual base.
2885  if (Overrider.Method->getParent() == MostDerivedClass ||
2886  !Overrider.VirtualBase)
2887  return;
2888 
2889  // Otherwise, we need to do use the dynamic offset of the final overrider
2890  // in order to get "this" adjustment right.
2892  (OffsetOfVBaseWithVFPtr + WhichVFPtr.NonVirtualOffset -
2893  MostDerivedClassLayout.getVBPtrOffset()).getQuantity();
2895  Context.getTypeSizeInChars(Context.IntTy).getQuantity() *
2896  VTables.getVBTableIndex(MostDerivedClass, Overrider.VirtualBase);
2897 
2898  TA.NonVirtual = (ThisOffset - Overrider.Offset).getQuantity();
2899 }
2900 
2902  const CXXRecordDecl *RD,
2903  SmallVector<const CXXMethodDecl *, 10> &VirtualMethods) {
2904  // Put the virtual methods into VirtualMethods in the proper order:
2905  // 1) Group overloads by declaration name. New groups are added to the
2906  // vftable in the order of their first declarations in this class
2907  // (including overrides, non-virtual methods and any other named decl that
2908  // might be nested within the class).
2909  // 2) In each group, new overloads appear in the reverse order of declaration.
2910  typedef SmallVector<const CXXMethodDecl *, 1> MethodGroup;
2912  typedef llvm::DenseMap<DeclarationName, unsigned> VisitedGroupIndicesTy;
2913  VisitedGroupIndicesTy VisitedGroupIndices;
2914  for (const auto *D : RD->decls()) {
2915  const auto *ND = dyn_cast<NamedDecl>(D);
2916  if (!ND)
2917  continue;
2918  VisitedGroupIndicesTy::iterator J;
2919  bool Inserted;
2920  std::tie(J, Inserted) = VisitedGroupIndices.insert(
2921  std::make_pair(ND->getDeclName(), Groups.size()));
2922  if (Inserted)
2923  Groups.push_back(MethodGroup());
2924  if (const auto *MD = dyn_cast<CXXMethodDecl>(ND))
2926  Groups[J->second].push_back(MD->getCanonicalDecl());
2927  }
2928 
2929  for (const MethodGroup &Group : Groups)
2930  VirtualMethods.append(Group.rbegin(), Group.rend());
2931 }
2932 
2933 static bool isDirectVBase(const CXXRecordDecl *Base, const CXXRecordDecl *RD) {
2934  for (const auto &B : RD->bases()) {
2935  if (B.isVirtual() && B.getType()->getAsCXXRecordDecl() == Base)
2936  return true;
2937  }
2938  return false;
2939 }
2940 
2941 void VFTableBuilder::AddMethods(BaseSubobject Base, unsigned BaseDepth,
2942  const CXXRecordDecl *LastVBase,
2943  BasesSetVectorTy &VisitedBases) {
2944  const CXXRecordDecl *RD = Base.getBase();
2945  if (!RD->isPolymorphic())
2946  return;
2947 
2948  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
2949 
2950  // See if this class expands a vftable of the base we look at, which is either
2951  // the one defined by the vfptr base path or the primary base of the current
2952  // class.
2953  const CXXRecordDecl *NextBase = nullptr, *NextLastVBase = LastVBase;
2954  CharUnits NextBaseOffset;
2955  if (BaseDepth < WhichVFPtr.PathToIntroducingObject.size()) {
2956  NextBase = WhichVFPtr.PathToIntroducingObject[BaseDepth];
2957  if (isDirectVBase(NextBase, RD)) {
2958  NextLastVBase = NextBase;
2959  NextBaseOffset = MostDerivedClassLayout.getVBaseClassOffset(NextBase);
2960  } else {
2961  NextBaseOffset =
2962  Base.getBaseOffset() + Layout.getBaseClassOffset(NextBase);
2963  }
2964  } else if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
2965  assert(!Layout.isPrimaryBaseVirtual() &&
2966  "No primary virtual bases in this ABI");
2967  NextBase = PrimaryBase;
2968  NextBaseOffset = Base.getBaseOffset();
2969  }
2970 
2971  if (NextBase) {
2972  AddMethods(BaseSubobject(NextBase, NextBaseOffset), BaseDepth + 1,
2973  NextLastVBase, VisitedBases);
2974  if (!VisitedBases.insert(NextBase))
2975  llvm_unreachable("Found a duplicate primary base!");
2976  }
2977 
2979  // Put virtual methods in the proper order.
2980  GroupNewVirtualOverloads(RD, VirtualMethods);
2981 
2982  // Now go through all virtual member functions and add them to the current
2983  // vftable. This is done by
2984  // - replacing overridden methods in their existing slots, as long as they
2985  // don't require return adjustment; calculating This adjustment if needed.
2986  // - adding new slots for methods of the current base not present in any
2987  // sub-bases;
2988  // - adding new slots for methods that require Return adjustment.
2989  // We keep track of the methods visited in the sub-bases in MethodInfoMap.
2990  for (const CXXMethodDecl *MD : VirtualMethods) {
2991  FinalOverriders::OverriderInfo FinalOverrider =
2992  Overriders.getOverrider(MD, Base.getBaseOffset());
2993  const CXXMethodDecl *FinalOverriderMD = FinalOverrider.Method;
2994  const CXXMethodDecl *OverriddenMD =
2995  FindNearestOverriddenMethod(MD, VisitedBases);
2996 
2997  ThisAdjustment ThisAdjustmentOffset;
2998  bool ReturnAdjustingThunk = false, ForceReturnAdjustmentMangling = false;
2999  CharUnits ThisOffset = ComputeThisOffset(FinalOverrider);
3000  ThisAdjustmentOffset.NonVirtual =
3001  (ThisOffset - WhichVFPtr.FullOffsetInMDC).getQuantity();
3002  if ((OverriddenMD || FinalOverriderMD != MD) &&
3003  WhichVFPtr.getVBaseWithVPtr())
3004  CalculateVtordispAdjustment(FinalOverrider, ThisOffset,
3005  ThisAdjustmentOffset);
3006 
3007  unsigned VBIndex =
3008  LastVBase ? VTables.getVBTableIndex(MostDerivedClass, LastVBase) : 0;
3009 
3010  if (OverriddenMD) {
3011  // If MD overrides anything in this vftable, we need to update the
3012  // entries.
3013  MethodInfoMapTy::iterator OverriddenMDIterator =
3014  MethodInfoMap.find(OverriddenMD);
3015 
3016  // If the overridden method went to a different vftable, skip it.
3017  if (OverriddenMDIterator == MethodInfoMap.end())
3018  continue;
3019 
3020  MethodInfo &OverriddenMethodInfo = OverriddenMDIterator->second;
3021 
3022  VBIndex = OverriddenMethodInfo.VBTableIndex;
3023 
3024  // Let's check if the overrider requires any return adjustments.
3025  // We must create a new slot if the MD's return type is not trivially
3026  // convertible to the OverriddenMD's one.
3027  // Once a chain of method overrides adds a return adjusting vftable slot,
3028  // all subsequent overrides will also use an extra method slot.
3029  ReturnAdjustingThunk = !ComputeReturnAdjustmentBaseOffset(
3030  Context, MD, OverriddenMD).isEmpty() ||
3031  OverriddenMethodInfo.UsesExtraSlot;
3032 
3033  if (!ReturnAdjustingThunk) {
3034  // No return adjustment needed - just replace the overridden method info
3035  // with the current info.
3036  MethodInfo MI(VBIndex, OverriddenMethodInfo.VFTableIndex);
3037  MethodInfoMap.erase(OverriddenMDIterator);
3038 
3039  assert(!MethodInfoMap.count(MD) &&
3040  "Should not have method info for this method yet!");
3041  MethodInfoMap.insert(std::make_pair(MD, MI));
3042  continue;
3043  }
3044 
3045  // In case we need a return adjustment, we'll add a new slot for
3046  // the overrider. Mark the overridden method as shadowed by the new slot.
3047  OverriddenMethodInfo.Shadowed = true;
3048 
3049  // Force a special name mangling for a return-adjusting thunk
3050  // unless the method is the final overrider without this adjustment.
3051  ForceReturnAdjustmentMangling =
3052  !(MD == FinalOverriderMD && ThisAdjustmentOffset.isEmpty());
3053  } else if (Base.getBaseOffset() != WhichVFPtr.FullOffsetInMDC ||
3054  MD->size_overridden_methods()) {
3055  // Skip methods that don't belong to the vftable of the current class,
3056  // e.g. each method that wasn't seen in any of the visited sub-bases
3057  // but overrides multiple methods of other sub-bases.
3058  continue;
3059  }
3060 
3061  // If we got here, MD is a method not seen in any of the sub-bases or
3062  // it requires return adjustment. Insert the method info for this method.
3063  MethodInfo MI(VBIndex,
3064  HasRTTIComponent ? Components.size() - 1 : Components.size(),
3065  ReturnAdjustingThunk);
3066 
3067  assert(!MethodInfoMap.count(MD) &&
3068  "Should not have method info for this method yet!");
3069  MethodInfoMap.insert(std::make_pair(MD, MI));
3070 
3071  // Check if this overrider needs a return adjustment.
3072  // We don't want to do this for pure virtual member functions.
3073  BaseOffset ReturnAdjustmentOffset;
3075  if (!FinalOverriderMD->isPure()) {
3076  ReturnAdjustmentOffset =
3077  ComputeReturnAdjustmentBaseOffset(Context, FinalOverriderMD, MD);
3078  }
3079  if (!ReturnAdjustmentOffset.isEmpty()) {
3080  ForceReturnAdjustmentMangling = true;
3081  ReturnAdjustment.NonVirtual =
3082  ReturnAdjustmentOffset.NonVirtualOffset.getQuantity();
3083  if (ReturnAdjustmentOffset.VirtualBase) {
3084  const ASTRecordLayout &DerivedLayout =
3085  Context.getASTRecordLayout(ReturnAdjustmentOffset.DerivedClass);
3086  ReturnAdjustment.Virtual.Microsoft.VBPtrOffset =
3087  DerivedLayout.getVBPtrOffset().getQuantity();
3088  ReturnAdjustment.Virtual.Microsoft.VBIndex =
3089  VTables.getVBTableIndex(ReturnAdjustmentOffset.DerivedClass,
3090  ReturnAdjustmentOffset.VirtualBase);
3091  }
3092  }
3093 
3094  AddMethod(FinalOverriderMD,
3095  ThunkInfo(ThisAdjustmentOffset, ReturnAdjustment,
3096  ForceReturnAdjustmentMangling ? MD : nullptr));
3097  }
3098 }
3099 
3100 static void PrintBasePath(const VPtrInfo::BasePath &Path, raw_ostream &Out) {
3101  for (const CXXRecordDecl *Elem :
3102  llvm::make_range(Path.rbegin(), Path.rend())) {
3103  Out << "'";
3104  Elem->printQualifiedName(Out);
3105  Out << "' in ";
3106  }
3107 }
3108 
3109 static void dumpMicrosoftThunkAdjustment(const ThunkInfo &TI, raw_ostream &Out,
3110  bool ContinueFirstLine) {
3111  const ReturnAdjustment &R = TI.Return;
3112  bool Multiline = false;
3113  const char *LinePrefix = "\n ";
3114  if (!R.isEmpty() || TI.Method) {
3115  if (!ContinueFirstLine)
3116  Out << LinePrefix;
3117  Out << "[return adjustment (to type '"
3119  << "'): ";
3121  Out << "vbptr at offset " << R.Virtual.Microsoft.VBPtrOffset << ", ";
3122  if (R.Virtual.Microsoft.VBIndex)
3123  Out << "vbase #" << R.Virtual.Microsoft.VBIndex << ", ";
3124  Out << R.NonVirtual << " non-virtual]";
3125  Multiline = true;
3126  }
3127 
3128  const ThisAdjustment &T = TI.This;
3129  if (!T.isEmpty()) {
3130  if (Multiline || !ContinueFirstLine)
3131  Out << LinePrefix;
3132  Out << "[this adjustment: ";
3133  if (!TI.This.Virtual.isEmpty()) {
3134  assert(T.Virtual.Microsoft.VtordispOffset < 0);
3135  Out << "vtordisp at " << T.Virtual.Microsoft.VtordispOffset << ", ";
3136  if (T.Virtual.Microsoft.VBPtrOffset) {
3137  Out << "vbptr at " << T.Virtual.Microsoft.VBPtrOffset
3138  << " to the left,";
3139  assert(T.Virtual.Microsoft.VBOffsetOffset > 0);
3140  Out << LinePrefix << " vboffset at "
3141  << T.Virtual.Microsoft.VBOffsetOffset << " in the vbtable, ";
3142  }
3143  }
3144  Out << T.NonVirtual << " non-virtual]";
3145  }
3146 }
3147 
3148 void VFTableBuilder::dumpLayout(raw_ostream &Out) {
3149  Out << "VFTable for ";
3150  PrintBasePath(WhichVFPtr.PathToIntroducingObject, Out);
3151  Out << "'";
3152  MostDerivedClass->printQualifiedName(Out);
3153  Out << "' (" << Components.size()
3154  << (Components.size() == 1 ? " entry" : " entries") << ").\n";
3155 
3156  for (unsigned I = 0, E = Components.size(); I != E; ++I) {
3157  Out << llvm::format("%4d | ", I);
3158 
3159  const VTableComponent &Component = Components[I];
3160 
3161  // Dump the component.
3162  switch (Component.getKind()) {
3164  Component.getRTTIDecl()->printQualifiedName(Out);
3165  Out << " RTTI";
3166  break;
3167 
3169  const CXXMethodDecl *MD = Component.getFunctionDecl();
3170 
3171  // FIXME: Figure out how to print the real thunk type, since they can
3172  // differ in the return type.
3173  std::string Str = PredefinedExpr::ComputeName(
3175  Out << Str;
3176  if (MD->isPure())
3177  Out << " [pure]";
3178 
3179  if (MD->isDeleted())
3180  Out << " [deleted]";
3181 
3182  ThunkInfo Thunk = VTableThunks.lookup(I);
3183  if (!Thunk.isEmpty())
3184  dumpMicrosoftThunkAdjustment(Thunk, Out, /*ContinueFirstLine=*/false);
3185 
3186  break;
3187  }
3188 
3190  const CXXDestructorDecl *DD = Component.getDestructorDecl();
3191 
3192  DD->printQualifiedName(Out);
3193  Out << "() [scalar deleting]";
3194 
3195  if (DD->isPure())
3196  Out << " [pure]";
3197 
3198  ThunkInfo Thunk = VTableThunks.lookup(I);
3199  if (!Thunk.isEmpty()) {
3200  assert(Thunk.Return.isEmpty() &&
3201  "No return adjustment needed for destructors!");
3202  dumpMicrosoftThunkAdjustment(Thunk, Out, /*ContinueFirstLine=*/false);
3203  }
3204 
3205  break;
3206  }
3207 
3208  default:
3209  DiagnosticsEngine &Diags = Context.getDiagnostics();
3210  unsigned DiagID = Diags.getCustomDiagID(
3212  "Unexpected vftable component type %0 for component number %1");
3213  Diags.Report(MostDerivedClass->getLocation(), DiagID)
3214  << I << Component.getKind();
3215  }
3216 
3217  Out << '\n';
3218  }
3219 
3220  Out << '\n';
3221 
3222  if (!Thunks.empty()) {
3223  // We store the method names in a map to get a stable order.
3224  std::map<std::string, const CXXMethodDecl *> MethodNamesAndDecls;
3225 
3226  for (const auto &I : Thunks) {
3227  const CXXMethodDecl *MD = I.first;
3228  std::string MethodName = PredefinedExpr::ComputeName(
3230 
3231  MethodNamesAndDecls.insert(std::make_pair(MethodName, MD));
3232  }
3233 
3234  for (const auto &MethodNameAndDecl : MethodNamesAndDecls) {
3235  const std::string &MethodName = MethodNameAndDecl.first;
3236  const CXXMethodDecl *MD = MethodNameAndDecl.second;
3237 
3238  ThunkInfoVectorTy ThunksVector = Thunks[MD];
3239  llvm::stable_sort(ThunksVector, [](const ThunkInfo &LHS,
3240  const ThunkInfo &RHS) {
3241  // Keep different thunks with the same adjustments in the order they
3242  // were put into the vector.
3243  return std::tie(LHS.This, LHS.Return) < std::tie(RHS.This, RHS.Return);
3244  });
3245 
3246  Out << "Thunks for '" << MethodName << "' (" << ThunksVector.size();
3247  Out << (ThunksVector.size() == 1 ? " entry" : " entries") << ").\n";
3248 
3249  for (unsigned I = 0, E = ThunksVector.size(); I != E; ++I) {
3250  const ThunkInfo &Thunk = ThunksVector[I];
3251 
3252  Out << llvm::format("%4d | ", I);
3253  dumpMicrosoftThunkAdjustment(Thunk, Out, /*ContinueFirstLine=*/true);
3254  Out << '\n';
3255  }
3256 
3257  Out << '\n';
3258  }
3259  }
3260 
3261  Out.flush();
3262 }
3263 
3266  for (const CXXRecordDecl *Decl : B) {
3267  if (A.count(Decl))
3268  return true;
3269  }
3270  return false;
3271 }
3272 
3273 static bool rebucketPaths(VPtrInfoVector &Paths);
3274 
3275 /// Produces MSVC-compatible vbtable data. The symbols produced by this
3276 /// algorithm match those produced by MSVC 2012 and newer, which is different
3277 /// from MSVC 2010.
3278 ///
3279 /// MSVC 2012 appears to minimize the vbtable names using the following
3280 /// algorithm. First, walk the class hierarchy in the usual order, depth first,
3281 /// left to right, to find all of the subobjects which contain a vbptr field.
3282 /// Visiting each class node yields a list of inheritance paths to vbptrs. Each
3283 /// record with a vbptr creates an initially empty path.
3284 ///
3285 /// To combine paths from child nodes, the paths are compared to check for
3286 /// ambiguity. Paths are "ambiguous" if multiple paths have the same set of
3287 /// components in the same order. Each group of ambiguous paths is extended by
3288 /// appending the class of the base from which it came. If the current class
3289 /// node produced an ambiguous path, its path is extended with the current class.
3290 /// After extending paths, MSVC again checks for ambiguity, and extends any
3291 /// ambiguous path which wasn't already extended. Because each node yields an
3292 /// unambiguous set of paths, MSVC doesn't need to extend any path more than once
3293 /// to produce an unambiguous set of paths.
3294 ///
3295 /// TODO: Presumably vftables use the same algorithm.
3296 void MicrosoftVTableContext::computeVTablePaths(bool ForVBTables,
3297  const CXXRecordDecl *RD,
3298  VPtrInfoVector &Paths) {
3299  assert(Paths.empty());
3300  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3301 
3302  // Base case: this subobject has its own vptr.
3303  if (ForVBTables ? Layout.hasOwnVBPtr() : Layout.hasOwnVFPtr())
3304  Paths.push_back(std::make_unique<VPtrInfo>(RD));
3305 
3306  // Recursive case: get all the vbtables from our bases and remove anything
3307  // that shares a virtual base.
3309  for (const auto &B : RD->bases()) {
3310  const CXXRecordDecl *Base = B.getType()->getAsCXXRecordDecl();
3311  if (B.isVirtual() && VBasesSeen.count(Base))
3312  continue;
3313 
3314  if (!Base->isDynamicClass())
3315  continue;
3316 
3317  const VPtrInfoVector &BasePaths =
3318  ForVBTables ? enumerateVBTables(Base) : getVFPtrOffsets(Base);
3319 
3320  for (const std::unique_ptr<VPtrInfo> &BaseInfo : BasePaths) {
3321  // Don't include the path if it goes through a virtual base that we've
3322  // already included.
3323  if (setsIntersect(VBasesSeen, BaseInfo->ContainingVBases))
3324  continue;
3325 
3326  // Copy the path and adjust it as necessary.
3327  auto P = std::make_unique<VPtrInfo>(*BaseInfo);
3328 
3329  // We mangle Base into the path if the path would've been ambiguous and it
3330  // wasn't already extended with Base.
3331  if (P->MangledPath.empty() || P->MangledPath.back() != Base)
3332  P->NextBaseToMangle = Base;
3333 
3334  // Keep track of which vtable the derived class is going to extend with
3335  // new methods or bases. We append to either the vftable of our primary
3336  // base, or the first non-virtual base that has a vbtable.
3337  if (P->ObjectWithVPtr == Base &&
3338  Base == (ForVBTables ? Layout.getBaseSharingVBPtr()
3339  : Layout.getPrimaryBase()))
3340  P->ObjectWithVPtr = RD;
3341 
3342  // Keep track of the full adjustment from the MDC to this vtable. The
3343  // adjustment is captured by an optional vbase and a non-virtual offset.
3344  if (B.isVirtual())
3345  P->ContainingVBases.push_back(Base);
3346  else if (P->ContainingVBases.empty())
3347  P->NonVirtualOffset += Layout.getBaseClassOffset(Base);
3348 
3349  // Update the full offset in the MDC.
3350  P->FullOffsetInMDC = P->NonVirtualOffset;
3351  if (const CXXRecordDecl *VB = P->getVBaseWithVPtr())
3352  P->FullOffsetInMDC += Layout.getVBaseClassOffset(VB);
3353 
3354  Paths.push_back(std::move(P));
3355  }
3356 
3357  if (B.isVirtual())
3358  VBasesSeen.insert(Base);
3359 
3360  // After visiting any direct base, we've transitively visited all of its
3361  // morally virtual bases.
3362  for (const auto &VB : Base->vbases())
3363  VBasesSeen.insert(VB.getType()->getAsCXXRecordDecl());
3364  }
3365 
3366  // Sort the paths into buckets, and if any of them are ambiguous, extend all
3367  // paths in ambiguous buckets.
3368  bool Changed = true;
3369  while (Changed)
3370  Changed = rebucketPaths(Paths);
3371 }
3372 
3373 static bool extendPath(VPtrInfo &P) {
3374  if (P.NextBaseToMangle) {
3375  P.MangledPath.push_back(P.NextBaseToMangle);
3376  P.NextBaseToMangle = nullptr;// Prevent the path from being extended twice.
3377  return true;
3378  }
3379  return false;
3380 }
3381 
3382 static bool rebucketPaths(VPtrInfoVector &Paths) {
3383  // What we're essentially doing here is bucketing together ambiguous paths.
3384  // Any bucket with more than one path in it gets extended by NextBase, which
3385  // is usually the direct base of the inherited the vbptr. This code uses a
3386  // sorted vector to implement a multiset to form the buckets. Note that the
3387  // ordering is based on pointers, but it doesn't change our output order. The
3388  // current algorithm is designed to match MSVC 2012's names.
3390  PathsSorted.reserve(Paths.size());
3391  for (auto& P : Paths)
3392  PathsSorted.push_back(*P);
3393  llvm::sort(PathsSorted, [](const VPtrInfo &LHS, const VPtrInfo &RHS) {
3394  return LHS.MangledPath < RHS.MangledPath;
3395  });
3396  bool Changed = false;
3397  for (size_t I = 0, E = PathsSorted.size(); I != E;) {
3398  // Scan forward to find the end of the bucket.
3399  size_t BucketStart = I;
3400  do {
3401  ++I;
3402  } while (I != E &&
3403  PathsSorted[BucketStart].get().MangledPath ==
3404  PathsSorted[I].get().MangledPath);
3405 
3406  // If this bucket has multiple paths, extend them all.
3407  if (I - BucketStart > 1) {
3408  for (size_t II = BucketStart; II != I; ++II)
3409  Changed |= extendPath(PathsSorted[II]);
3410  assert(Changed && "no paths were extended to fix ambiguity");
3411  }
3412  }
3413  return Changed;
3414 }
3415 
3417 
3418 namespace {
3419 typedef llvm::SetVector<BaseSubobject, std::vector<BaseSubobject>,
3420  llvm::DenseSet<BaseSubobject>> FullPathTy;
3421 }
3422 
3423 // This recursive function finds all paths from a subobject centered at
3424 // (RD, Offset) to the subobject located at IntroducingObject.
3425 static void findPathsToSubobject(ASTContext &Context,
3426  const ASTRecordLayout &MostDerivedLayout,
3427  const CXXRecordDecl *RD, CharUnits Offset,
3428  BaseSubobject IntroducingObject,
3429  FullPathTy &FullPath,
3430  std::list<FullPathTy> &Paths) {
3431  if (BaseSubobject(RD, Offset) == IntroducingObject) {
3432  Paths.push_back(FullPath);
3433  return;
3434  }
3435 
3436  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3437 
3438  for (const CXXBaseSpecifier &BS : RD->bases()) {
3439  const CXXRecordDecl *Base = BS.getType()->getAsCXXRecordDecl();
3440  CharUnits NewOffset = BS.isVirtual()
3441  ? MostDerivedLayout.getVBaseClassOffset(Base)
3442  : Offset + Layout.getBaseClassOffset(Base);
3443  FullPath.insert(BaseSubobject(Base, NewOffset));
3444  findPathsToSubobject(Context, MostDerivedLayout, Base, NewOffset,
3445  IntroducingObject, FullPath, Paths);
3446  FullPath.pop_back();
3447  }
3448 }
3449 
3450 // Return the paths which are not subsets of other paths.
3451 static void removeRedundantPaths(std::list<FullPathTy> &FullPaths) {
3452  FullPaths.remove_if([&](const FullPathTy &SpecificPath) {
3453  for (const FullPathTy &OtherPath : FullPaths) {
3454  if (&SpecificPath == &OtherPath)
3455  continue;
3456  if (llvm::all_of(SpecificPath, [&](const BaseSubobject &BSO) {
3457  return OtherPath.count(BSO) != 0;
3458  })) {
3459  return true;
3460  }
3461  }
3462  return false;
3463  });
3464 }
3465 
3467  const CXXRecordDecl *RD,
3468  const FullPathTy &FullPath) {
3469  const ASTRecordLayout &MostDerivedLayout =
3470  Context.getASTRecordLayout(RD);
3472  for (const BaseSubobject &BSO : FullPath) {
3473  const CXXRecordDecl *Base = BSO.getBase();
3474  // The first entry in the path is always the most derived record, skip it.
3475  if (Base == RD) {
3476  assert(Offset.getQuantity() == -1);
3477  Offset = CharUnits::Zero();
3478  continue;
3479  }
3480  assert(Offset.getQuantity() != -1);
3481  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3482  // While we know which base has to be traversed, we don't know if that base
3483  // was a virtual base.
3484  const CXXBaseSpecifier *BaseBS = std::find_if(
3485  RD->bases_begin(), RD->bases_end(), [&](const CXXBaseSpecifier &BS) {
3486  return BS.getType()->getAsCXXRecordDecl() == Base;
3487  });
3488  Offset = BaseBS->isVirtual() ? MostDerivedLayout.getVBaseClassOffset(Base)
3489  : Offset + Layout.getBaseClassOffset(Base);
3490  RD = Base;
3491  }
3492  return Offset;
3493 }
3494 
3495 // We want to select the path which introduces the most covariant overrides. If
3496 // two paths introduce overrides which the other path doesn't contain, issue a
3497 // diagnostic.
3498 static const FullPathTy *selectBestPath(ASTContext &Context,
3499  const CXXRecordDecl *RD,
3500  const VPtrInfo &Info,
3501  std::list<FullPathTy> &FullPaths) {
3502  // Handle some easy cases first.
3503  if (FullPaths.empty())
3504  return nullptr;
3505  if (FullPaths.size() == 1)
3506  return &FullPaths.front();
3507 
3508  const FullPathTy *BestPath = nullptr;
3509  typedef std::set<const CXXMethodDecl *> OverriderSetTy;
3510  OverriderSetTy LastOverrides;
3511  for (const FullPathTy &SpecificPath : FullPaths) {
3512  assert(!SpecificPath.empty());
3513  OverriderSetTy CurrentOverrides;
3514  const CXXRecordDecl *TopLevelRD = SpecificPath.begin()->getBase();
3515  // Find the distance from the start of the path to the subobject with the
3516  // VPtr.
3517  CharUnits BaseOffset =
3518  getOffsetOfFullPath(Context, TopLevelRD, SpecificPath);
3519  FinalOverriders Overriders(TopLevelRD, CharUnits::Zero(), TopLevelRD);
3520  for (const CXXMethodDecl *MD : Info.IntroducingObject->methods()) {
3522  continue;
3523  FinalOverriders::OverriderInfo OI =
3524  Overriders.getOverrider(MD->getCanonicalDecl(), BaseOffset);
3525  const CXXMethodDecl *OverridingMethod = OI.Method;
3526  // Only overriders which have a return adjustment introduce problematic
3527  // thunks.
3528  if (ComputeReturnAdjustmentBaseOffset(Context, OverridingMethod, MD)
3529  .isEmpty())
3530  continue;
3531  // It's possible that the overrider isn't in this path. If so, skip it
3532  // because this path didn't introduce it.
3533  const CXXRecordDecl *OverridingParent = OverridingMethod->getParent();
3534  if (llvm::none_of(SpecificPath, [&](const BaseSubobject &BSO) {
3535  return BSO.getBase() == OverridingParent;
3536  }))
3537  continue;
3538  CurrentOverrides.insert(OverridingMethod);
3539  }
3540  OverriderSetTy NewOverrides =
3541  llvm::set_difference(CurrentOverrides, LastOverrides);
3542  if (NewOverrides.empty())
3543  continue;
3544  OverriderSetTy MissingOverrides =
3545  llvm::set_difference(LastOverrides, CurrentOverrides);
3546  if (MissingOverrides.empty()) {
3547  // This path is a strict improvement over the last path, let's use it.
3548  BestPath = &SpecificPath;
3549  std::swap(CurrentOverrides, LastOverrides);
3550  } else {
3551  // This path introduces an overrider with a conflicting covariant thunk.
3552  DiagnosticsEngine &Diags = Context.getDiagnostics();
3553  const CXXMethodDecl *CovariantMD = *NewOverrides.begin();
3554  const CXXMethodDecl *ConflictMD = *MissingOverrides.begin();
3555  Diags.Report(RD->getLocation(), diag::err_vftable_ambiguous_component)
3556  << RD;
3557  Diags.Report(CovariantMD->getLocation(), diag::note_covariant_thunk)
3558  << CovariantMD;
3559  Diags.Report(ConflictMD->getLocation(), diag::note_covariant_thunk)
3560  << ConflictMD;
3561  }
3562  }
3563  // Go with the path that introduced the most covariant overrides. If there is
3564  // no such path, pick the first path.
3565  return BestPath ? BestPath : &FullPaths.front();
3566 }
3567 
3569  const CXXRecordDecl *RD,
3570  VPtrInfoVector &Paths) {
3571  const ASTRecordLayout &MostDerivedLayout = Context.getASTRecordLayout(RD);
3572  FullPathTy FullPath;
3573  std::list<FullPathTy> FullPaths;
3574  for (const std::unique_ptr<VPtrInfo>& Info : Paths) {
3576  Context, MostDerivedLayout, RD, CharUnits::Zero(),
3577  BaseSubobject(Info->IntroducingObject, Info->FullOffsetInMDC), FullPath,
3578  FullPaths);
3579  FullPath.clear();
3580  removeRedundantPaths(FullPaths);
3581  Info->PathToIntroducingObject.clear();
3582  if (const FullPathTy *BestPath =
3583  selectBestPath(Context, RD, *Info, FullPaths))
3584  for (const BaseSubobject &BSO : *BestPath)
3585  Info->PathToIntroducingObject.push_back(BSO.getBase());
3586  FullPaths.clear();
3587  }
3588 }
3589 
3590 static bool vfptrIsEarlierInMDC(const ASTRecordLayout &Layout,
3591  const MethodVFTableLocation &LHS,
3592  const MethodVFTableLocation &RHS) {
3593  CharUnits L = LHS.VFPtrOffset;
3594  CharUnits R = RHS.VFPtrOffset;
3595  if (LHS.VBase)
3596  L += Layout.getVBaseClassOffset(LHS.VBase);
3597  if (RHS.VBase)
3598  R += Layout.getVBaseClassOffset(RHS.VBase);
3599  return L < R;
3600 }
3601 
3602 void MicrosoftVTableContext::computeVTableRelatedInformation(
3603  const CXXRecordDecl *RD) {
3604  assert(RD->isDynamicClass());
3605 
3606  // Check if we've computed this information before.
3607  if (VFPtrLocations.count(RD))
3608  return;
3609 
3610  const VTableLayout::AddressPointsMapTy EmptyAddressPointsMap;
3611 
3612  {
3613  auto VFPtrs = std::make_unique<VPtrInfoVector>();
3614  computeVTablePaths(/*ForVBTables=*/false, RD, *VFPtrs);
3615  computeFullPathsForVFTables(Context, RD, *VFPtrs);
3616  VFPtrLocations[RD] = std::move(VFPtrs);
3617  }
3618 
3619  MethodVFTableLocationsTy NewMethodLocations;
3620  for (const std::unique_ptr<VPtrInfo> &VFPtr : *VFPtrLocations[RD]) {
3621  VFTableBuilder Builder(*this, RD, *VFPtr);
3622 
3623  VFTableIdTy id(RD, VFPtr->FullOffsetInMDC);
3624  assert(VFTableLayouts.count(id) == 0);
3626  Builder.vtable_thunks_begin(), Builder.vtable_thunks_end());
3627  VFTableLayouts[id] = std::make_unique<VTableLayout>(
3628  ArrayRef<size_t>{0}, Builder.vtable_components(), VTableThunks,
3629  EmptyAddressPointsMap);
3630  Thunks.insert(Builder.thunks_begin(), Builder.thunks_end());
3631 
3632  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3633  for (const auto &Loc : Builder.vtable_locations()) {
3634  auto Insert = NewMethodLocations.insert(Loc);
3635  if (!Insert.second) {
3636  const MethodVFTableLocation &NewLoc = Loc.second;
3637  MethodVFTableLocation &OldLoc = Insert.first->second;
3638  if (vfptrIsEarlierInMDC(Layout, NewLoc, OldLoc))
3639  OldLoc = NewLoc;
3640  }
3641  }
3642  }
3643 
3644  MethodVFTableLocations.insert(NewMethodLocations.begin(),
3645  NewMethodLocations.end());
3646  if (Context.getLangOpts().DumpVTableLayouts)
3647  dumpMethodLocations(RD, NewMethodLocations, llvm::outs());
3648 }
3649 
3650 void MicrosoftVTableContext::dumpMethodLocations(
3651  const CXXRecordDecl *RD, const MethodVFTableLocationsTy &NewMethods,
3652  raw_ostream &Out) {
3653  // Compute the vtable indices for all the member functions.
3654  // Store them in a map keyed by the location so we'll get a sorted table.
3655  std::map<MethodVFTableLocation, std::string> IndicesMap;
3656  bool HasNonzeroOffset = false;
3657 
3658  for (const auto &I : NewMethods) {
3659  const CXXMethodDecl *MD = cast<const CXXMethodDecl>(I.first.getDecl());
3660  assert(hasVtableSlot(MD));
3661 
3662  std::string MethodName = PredefinedExpr::ComputeName(
3664 
3665  if (isa<CXXDestructorDecl>(MD)) {
3666  IndicesMap[I.second] = MethodName + " [scalar deleting]";
3667  } else {
3668  IndicesMap[I.second] = MethodName;
3669  }
3670 
3671  if (!I.second.VFPtrOffset.isZero() || I.second.VBTableIndex != 0)
3672  HasNonzeroOffset = true;
3673  }
3674 
3675  // Print the vtable indices for all the member functions.
3676  if (!IndicesMap.empty()) {
3677  Out << "VFTable indices for ";
3678  Out << "'";
3679  RD->printQualifiedName(Out);
3680  Out << "' (" << IndicesMap.size()
3681  << (IndicesMap.size() == 1 ? " entry" : " entries") << ").\n";
3682 
3683  CharUnits LastVFPtrOffset = CharUnits::fromQuantity(-1);
3684  uint64_t LastVBIndex = 0;
3685  for (const auto &I : IndicesMap) {
3686  CharUnits VFPtrOffset = I.first.VFPtrOffset;
3687  uint64_t VBIndex = I.first.VBTableIndex;
3688  if (HasNonzeroOffset &&
3689  (VFPtrOffset != LastVFPtrOffset || VBIndex != LastVBIndex)) {
3690  assert(VBIndex > LastVBIndex || VFPtrOffset > LastVFPtrOffset);
3691  Out << " -- accessible via ";
3692  if (VBIndex)
3693  Out << "vbtable index " << VBIndex << ", ";
3694  Out << "vfptr at offset " << VFPtrOffset.getQuantity() << " --\n";
3695  LastVFPtrOffset = VFPtrOffset;
3696  LastVBIndex = VBIndex;
3697  }
3698 
3699  uint64_t VTableIndex = I.first.Index;
3700  const std::string &MethodName = I.second;
3701  Out << llvm::format("%4" PRIu64 " | ", VTableIndex) << MethodName << '\n';
3702  }
3703  Out << '\n';
3704  }
3705 
3706  Out.flush();
3707 }
3708 
3709 const VirtualBaseInfo &MicrosoftVTableContext::computeVBTableRelatedInformation(
3710  const CXXRecordDecl *RD) {
3711  VirtualBaseInfo *VBI;
3712 
3713  {
3714  // Get or create a VBI for RD. Don't hold a reference to the DenseMap cell,
3715  // as it may be modified and rehashed under us.
3716  std::unique_ptr<VirtualBaseInfo> &Entry = VBaseInfo[RD];
3717  if (Entry)
3718  return *Entry;
3719  Entry = std::make_unique<VirtualBaseInfo>();
3720  VBI = Entry.get();
3721  }
3722 
3723  computeVTablePaths(/*ForVBTables=*/true, RD, VBI->VBPtrPaths);
3724 
3725  // First, see if the Derived class shared the vbptr with a non-virtual base.
3726  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3727  if (const CXXRecordDecl *VBPtrBase = Layout.getBaseSharingVBPtr()) {
3728  // If the Derived class shares the vbptr with a non-virtual base, the shared
3729  // virtual bases come first so that the layout is the same.
3730  const VirtualBaseInfo &BaseInfo =
3731  computeVBTableRelatedInformation(VBPtrBase);
3732  VBI->VBTableIndices.insert(BaseInfo.VBTableIndices.begin(),
3733  BaseInfo.VBTableIndices.end());
3734  }
3735 
3736  // New vbases are added to the end of the vbtable.
3737  // Skip the self entry and vbases visited in the non-virtual base, if any.
3738  unsigned VBTableIndex = 1 + VBI->VBTableIndices.size();
3739  for (const auto &VB : RD->vbases()) {
3740  const CXXRecordDecl *CurVBase = VB.getType()->getAsCXXRecordDecl();
3741  if (!VBI->VBTableIndices.count(CurVBase))
3742  VBI->VBTableIndices[CurVBase] = VBTableIndex++;
3743  }
3744 
3745  return *VBI;
3746 }
3747 
3749  const CXXRecordDecl *VBase) {
3750  const VirtualBaseInfo &VBInfo = computeVBTableRelatedInformation(Derived);
3751  assert(VBInfo.VBTableIndices.count(VBase));
3752  return VBInfo.VBTableIndices.find(VBase)->second;
3753 }
3754 
3755 const VPtrInfoVector &
3757  return computeVBTableRelatedInformation(RD).VBPtrPaths;
3758 }
3759 
3760 const VPtrInfoVector &
3762  computeVTableRelatedInformation(RD);
3763 
3764  assert(VFPtrLocations.count(RD) && "Couldn't find vfptr locations");
3765  return *VFPtrLocations[RD];
3766 }
3767 
3768 const VTableLayout &
3770  CharUnits VFPtrOffset) {
3771  computeVTableRelatedInformation(RD);
3772 
3773  VFTableIdTy id(RD, VFPtrOffset);
3774  assert(VFTableLayouts.count(id) && "Couldn't find a VFTable at this offset");
3775  return *VFTableLayouts[id];
3776 }
3777 
3780  assert(hasVtableSlot(cast<CXXMethodDecl>(GD.getDecl())) &&
3781  "Only use this method for virtual methods or dtors");
3782  if (isa<CXXDestructorDecl>(GD.getDecl()))
3783  assert(GD.getDtorType() == Dtor_Deleting);
3784 
3785  GD = GD.getCanonicalDecl();
3786 
3787  MethodVFTableLocationsTy::iterator I = MethodVFTableLocations.find(GD);
3788  if (I != MethodVFTableLocations.end())
3789  return I->second;
3790 
3791  const CXXRecordDecl *RD = cast<CXXMethodDecl>(GD.getDecl())->getParent();
3792 
3793  computeVTableRelatedInformation(RD);
3794 
3795  I = MethodVFTableLocations.find(GD);
3796  assert(I != MethodVFTableLocations.end() && "Did not find index!");
3797  return I->second;
3798 }
Defines the clang::ASTContext interface.
if(T->getSizeExpr()) TRY_TO(TraverseStmt(T -> getSizeExpr()))
PointerType - C99 6.7.5.1 - Pointer Declarators.
Definition: Type.h:2645
bool isPrimaryBaseVirtual() const
isPrimaryBaseVirtual - Get whether the primary base for this record is virtual or not...
Definition: RecordLayout.h:225
A (possibly-)qualified type.
Definition: Type.h:655
base_class_range bases()
Definition: DeclCXX.h:588
uint32_t VBPtrOffset
The offset (in bytes) of the vbptr, relative to the beginning of the derived class.
Definition: ABI.h:60
bool isEmpty() const
Definition: ABI.h:154
CXXDtorType getDtorType() const
Definition: GlobalDecl.h:108
static VTableComponent MakeRTTI(const CXXRecordDecl *RD)
Definition: VTableBuilder.h:66
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:3547
CharUnits getBaseClassOffset(const CXXRecordDecl *Base) const
getBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:232
unsigned getNumVBases() const
Retrieves the number of virtual base classes of this class.
Definition: DeclCXX.h:603
VPtrInfoVector VBPtrPaths
Information on all virtual base tables used when this record is the most derived class.
bool isEmpty() const
Definition: ABI.h:86
Decl - This represents one declaration (or definition), e.g.
Definition: DeclBase.h:89
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:2005
bool isVirtual() const
Determines whether the base class is a virtual base class (or not).
Definition: DeclCXX.h:199
StringRef P
GlobalDecl getCanonicalDecl() const
Definition: GlobalDecl.h:92
int64_t NonVirtual
The non-virtual adjustment from the derived object to its nearest virtual base.
Definition: ABI.h:110
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:1330
bool isZero() const
isZero - Test whether the quantity equals zero.
Definition: CharUnits.h:116
const TargetInfo & getTargetInfo() const
Definition: ASTContext.h:647
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:88
const CXXMethodDecl * getUnusedFunctionDecl() const
static VTableLayout::AddressPointsIndexMapTy MakeAddressPointIndices(const VTableLayout::AddressPointsMapTy &addressPoints, unsigned numVTables)
QualType getReturnType() const
Definition: Decl.h:2456
const CXXRecordDecl * VBase
If nonnull, holds the last vbase which contains the vfptr that the method definition is adjusted to...
decl_range decls() const
decls_begin/decls_end - Iterate over the declarations stored in this context.
Definition: DeclBase.h:2065
static VTableComponent MakeVCallOffset(CharUnits Offset)
Definition: VTableBuilder.h:54
A this pointer adjustment.
Definition: ABI.h:107
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:190
bool isMoveAssignmentOperator() const
Determine whether this is a move assignment operator.
Definition: DeclCXX.cpp:2327
CharUnits getBaseOffset() const
getBaseOffset - Returns the base class offset.
Definition: BaseSubobject.h:46
ItaniumVTableContext(ASTContext &Context, VTableComponentLayout ComponentLayout=Pointer)
uint64_t getPointerWidth(unsigned AddrSpace) const
Return the width of pointers on this target, for the specified address space.
Definition: TargetInfo.h:397
int32_t VBOffsetOffset
The offset (in bytes) of the vbase offset in the vbtable.
Definition: ABI.h:131
DeclarationName getDeclName() const
Get the actual, stored name of the declaration, which may be a special name.
Definition: Decl.h:272
TargetCXXABI getCXXABI() const
Get the C++ ABI currently in use.
Definition: TargetInfo.h:1129
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:174
ArrayRef< QualType > getParamTypes() const
Definition: Type.h:4103
CXXMethodDecl * getCanonicalDecl() override
Retrieves the "canonical" declaration of the given declaration.
Definition: DeclCXX.h:2046
static VTableComponent MakeCompleteDtor(const CXXDestructorDecl *DD)
Definition: VTableBuilder.h:78
static bool hasVtableSlot(const CXXMethodDecl *MD)
Determine whether this function should be assigned a vtable slot.
A return adjustment.
Definition: ABI.h:41
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:240
The this pointer adjustment as well as an optional return adjustment for a thunk. ...
Definition: ABI.h:178
const CXXRecordDecl * NextBaseToMangle
The next base to push onto the mangled path if this path is ambiguous in a derived class...
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:34
Concrete class used by the front-end to report problems and issues.
Definition: Diagnostic.h:153
const VPtrInfoVector & getVFPtrOffsets(const CXXRecordDecl *RD)
struct clang::ThisAdjustment::VirtualAdjustment::@131 Itanium
base_class_iterator bases_begin()
Definition: DeclCXX.h:595
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:83
CXXRecordDecl * getAsCXXRecordDecl() const
Retrieves the CXXRecordDecl that this type refers to, either because the type is a RecordType or beca...
Definition: Type.cpp:1758
Represents a prototype with parameter type info, e.g.
Definition: Type.h:3886
bool isDynamicClass() const
Definition: DeclCXX.h:554
OverloadedOperatorKind getOverloadedOperator() const
getOverloadedOperator - Which C++ overloaded operator this function represents, if any...
Definition: Decl.cpp:3515
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:2020
ASTRecordLayout - This class contains layout information for one RecordDecl, which is a struct/union/...
Definition: RecordLayout.h:38
bool isConsteval() const
Definition: Decl.h:2210
struct clang::ReturnAdjustment::VirtualAdjustment::@129 Itanium
static void GroupNewVirtualOverloads(const CXXRecordDecl *RD, SmallVector< const CXXMethodDecl *, 10 > &VirtualMethods)
SmallVector< ThunkInfo, 1 > ThunkInfoVectorTy
const T * castAs() const
Member-template castAs<specific type>.
Definition: Type.h:7218
Kind getKind() const
Get the kind of this vtable component.
Definition: VTableBuilder.h:96
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:2679
bool isImplicit() const
isImplicit - Indicates whether the declaration was implicitly generated by the implementation.
Definition: DeclBase.h:563
overridden_method_range overridden_methods() const
Definition: DeclCXX.cpp:2373
CharUnits getOffsetToTop() const
CharUnits getVCallOffset() const
const CXXRecordDecl * getPrimaryBase() const
getPrimaryBase - Get the primary base for this record.
Definition: RecordLayout.h:217
static CharUnits fromQuantity(QuantityType Quantity)
fromQuantity - Construct a CharUnits quantity from a raw integer type.
Definition: CharUnits.h:63
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:1148
DeclContext * getParent()
getParent - Returns the containing DeclContext.
Definition: DeclBase.h:1816
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:305
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:1537
GlobalDecl - represents a global declaration.
Definition: GlobalDecl.h:54
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:44
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:17
QualType getCanonicalType() const
Definition: Type.h:6441
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:3810
bool isPure() const
Whether this virtual function is pure, i.e.
Definition: Decl.h:2105
static bool Ret(InterpState &S, CodePtr &PC, APValue &Result)
Definition: Interp.cpp:34
static void dumpMicrosoftThunkAdjustment(const ThunkInfo &TI, raw_ostream &Out, bool ContinueFirstLine)
ASTContext & getASTContext() const LLVM_READONLY
Definition: DeclBase.cpp:414
static bool vfptrIsEarlierInMDC(const ASTRecordLayout &Layout, const MethodVFTableLocation &LHS, const MethodVFTableLocation &RHS)
const Decl * getDecl() const
Definition: GlobalDecl.h:101
Represents a single component in a vtable.
Definition: VTableBuilder.h:29
Represents a static or instance method of a struct/union/class.
Definition: DeclCXX.h:1960
static std::string ComputeName(IdentKind IK, const Decl *CurrentDecl)
Definition: Expr.cpp:630
const VTableLayout & getVFTableLayout(const CXXRecordDecl *RD, CharUnits VFPtrOffset)
Qualifiers getMethodQuals() const
Definition: Type.h:4236
The same as PrettyFunction, except that the &#39;virtual&#39; keyword is omitted for virtual member functions...
Definition: Expr.h:1937
unsigned getCustomDiagID(Level L, const char(&FormatString)[N])
Return an ID for a diagnostic with the specified format string and level.
Definition: Diagnostic.h:786
int64_t VCallOffsetOffset
The offset (in bytes), relative to the address point, of the virtual call offset. ...
Definition: ABI.h:119
Complete object dtor.
Definition: ABI.h:35
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:58
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:180
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:997
const CXXRecordDecl * getParent() const
Return the parent of this method declaration, which is the class in which this method is defined...
Definition: DeclCXX.h:2076
const CXXRecordDecl * getBaseSharingVBPtr() const
Definition: RecordLayout.h:310
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:53
bool isCopyAssignmentOperator() const
Determine whether this is a copy-assignment operator, regardless of whether it was declared implicitl...
Definition: DeclCXX.cpp:2306
CharUnits NonVirtualOffset
IntroducingObject is at this offset from its containing complete object or virtual base...
base_class_iterator vbases_begin()
Definition: DeclCXX.h:612
bool isEmpty() const
Definition: ABI.h:203
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:2756
ReturnAdjustment Return
The return adjustment.
Definition: ABI.h:183
Represents a base class of a C++ class.
Definition: DeclCXX.h:146
CanQualType getCanonicalType(QualType T) const
Return the canonical (structural) type corresponding to the specified potentially non-canonical type ...
Definition: ASTContext.h:2259
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:254
int32_t VtordispOffset
The offset of the vtordisp (in bytes), relative to the ECX.
Definition: ABI.h:124
base_class_iterator bases_end()
Definition: DeclCXX.h:597
ASTImporterLookupTable & LT
std::pair< uint64_t, ThunkInfo > VTableThunkTy
llvm::DenseMap< const CXXRecordDecl *, VBaseInfo > VBaseOffsetsMapTy
Definition: RecordLayout.h:59
Defines the clang::TargetInfo interface.
bool isMicrosoft() const
Is this ABI an MSVC-compatible ABI?
Definition: TargetCXXABI.h:168
A pointer to the deleting destructor.
Definition: VTableBuilder.h:42
static Decl::Kind getKind(const Decl *D)
Definition: DeclBase.cpp:996
CanQualType IntTy
Definition: ASTContext.h:951
MethodVFTableLocation getMethodVFTableLocation(GlobalDecl GD)
static VTableComponent MakeFunction(const CXXMethodDecl *MD)
Definition: VTableBuilder.h:70
bool isDeleted() const
Whether this function has been deleted.
Definition: Decl.h:2257
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:630
uint32_t VBIndex
Index of the virtual base in the vbtable.
Definition: ABI.h:63
This represents a decl that may have a name.
Definition: Decl.h:223
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:128
const LangOptions & getLangOpts() const
Definition: ASTContext.h:664
base_class_range vbases()
Definition: DeclCXX.h:605
A pointer to the complete destructor.
Definition: VTableBuilder.h:39
SourceLocation getLocation() const
Definition: DeclBase.h:430
method_range methods() const
Definition: DeclCXX.h:630
QualType getType() const
Retrieves the type of the base class.
Definition: DeclCXX.h:245
static VTableComponent MakeOffsetToTop(CharUnits Offset)
Definition: VTableBuilder.h:62