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
13#include "clang/AST/VTableBuilder.h"
14#include "clang/AST/ASTContext.h"
15#include "clang/AST/ASTDiagnostic.h"
16#include "clang/AST/CXXInheritance.h"
17#include "clang/AST/RecordLayout.h"
18#include "clang/Basic/TargetInfo.h"
19#include "llvm/ADT/SetOperations.h"
20#include "llvm/ADT/SetVector.h"
21#include "llvm/ADT/SmallPtrSet.h"
22#include "llvm/Support/Format.h"
23#include "llvm/Support/raw_ostream.h"
24#include <algorithm>
25#include <cstdio>
26
27using namespace clang;
28
29#define DUMP_OVERRIDERS 0
30
31namespace {
32
33/// BaseOffset - Represents an offset from a derived class to a direct or
34/// indirect base class.
35struct BaseOffset {
36 /// DerivedClass - The derived class.
37 const CXXRecordDecl *DerivedClass;
38
39 /// VirtualBase - If the path from the derived class to the base class
40 /// involves virtual base classes, this holds the declaration of the last
41 /// virtual base in this path (i.e. closest to the base class).
42 const CXXRecordDecl *VirtualBase;
43
44 /// NonVirtualOffset - The offset from the derived class to the base class.
45 /// (Or the offset from the virtual base class to the base class, if the
46 /// path from the derived class to the base class involves a virtual base
47 /// class.
48 CharUnits NonVirtualOffset;
49
50 BaseOffset() : DerivedClass(nullptr), VirtualBase(nullptr),
51 NonVirtualOffset(CharUnits::Zero()) { }
52 BaseOffset(const CXXRecordDecl *DerivedClass,
53 const CXXRecordDecl *VirtualBase, CharUnits NonVirtualOffset)
54 : DerivedClass(DerivedClass), VirtualBase(VirtualBase),
55 NonVirtualOffset(NonVirtualOffset) { }
56
57 bool isEmpty() const { return NonVirtualOffset.isZero() && !VirtualBase; }
58};
59
60/// FinalOverriders - Contains the final overrider member functions for all
61/// member functions in the base subobjects of a class.
62class FinalOverriders {
63public:
64 /// OverriderInfo - Information about a final overrider.
65 struct OverriderInfo {
66 /// Method - The method decl of the overrider.
67 const CXXMethodDecl *Method;
68
69 /// VirtualBase - The virtual base class subobject of this overrider.
70 /// Note that this records the closest derived virtual base class subobject.
71 const CXXRecordDecl *VirtualBase;
72
73 /// Offset - the base offset of the overrider's parent in the layout class.
74 CharUnits Offset;
75
76 OverriderInfo() : Method(nullptr), VirtualBase(nullptr),
77 Offset(CharUnits::Zero()) { }
78 };
79
80private:
81 /// MostDerivedClass - The most derived class for which the final overriders
82 /// are stored.
83 const CXXRecordDecl *MostDerivedClass;
84
85 /// MostDerivedClassOffset - If we're building final overriders for a
86 /// construction vtable, this holds the offset from the layout class to the
87 /// most derived class.
88 const CharUnits MostDerivedClassOffset;
89
90 /// LayoutClass - The class we're using for layout information. Will be
91 /// different than the most derived class if the final overriders are for a
92 /// construction vtable.
93 const CXXRecordDecl *LayoutClass;
94
95 ASTContext &Context;
96
97 /// MostDerivedClassLayout - the AST record layout of the most derived class.
98 const ASTRecordLayout &MostDerivedClassLayout;
99
100 /// MethodBaseOffsetPairTy - Uniquely identifies a member function
101 /// in a base subobject.
102 typedef std::pair<const CXXMethodDecl *, CharUnits> MethodBaseOffsetPairTy;
103
104 typedef llvm::DenseMap<MethodBaseOffsetPairTy,
105 OverriderInfo> OverridersMapTy;
106
107 /// OverridersMap - The final overriders for all virtual member functions of
108 /// all the base subobjects of the most derived class.
109 OverridersMapTy OverridersMap;
110
111 /// SubobjectsToOffsetsMapTy - A mapping from a base subobject (represented
112 /// as a record decl and a subobject number) and its offsets in the most
113 /// derived class as well as the layout class.
114 typedef llvm::DenseMap<std::pair<const CXXRecordDecl *, unsigned>,
115 CharUnits> SubobjectOffsetMapTy;
116
117 typedef llvm::DenseMap<const CXXRecordDecl *, unsigned> SubobjectCountMapTy;
118
119 /// ComputeBaseOffsets - Compute the offsets for all base subobjects of the
120 /// given base.
121 void ComputeBaseOffsets(BaseSubobject Base, bool IsVirtual,
122 CharUnits OffsetInLayoutClass,
123 SubobjectOffsetMapTy &SubobjectOffsets,
124 SubobjectOffsetMapTy &SubobjectLayoutClassOffsets,
125 SubobjectCountMapTy &SubobjectCounts);
126
127 typedef llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBasesSetTy;
128
129 /// dump - dump the final overriders for a base subobject, and all its direct
130 /// and indirect base subobjects.
131 void dump(raw_ostream &Out, BaseSubobject Base,
132 VisitedVirtualBasesSetTy& VisitedVirtualBases);
133
134public:
135 FinalOverriders(const CXXRecordDecl *MostDerivedClass,
136 CharUnits MostDerivedClassOffset,
137 const CXXRecordDecl *LayoutClass);
138
139 /// getOverrider - Get the final overrider for the given method declaration in
140 /// the subobject with the given base offset.
141 OverriderInfo getOverrider(const CXXMethodDecl *MD,
142 CharUnits BaseOffset) const {
143 assert(OverridersMap.count(std::make_pair(MD, BaseOffset)) &&
144 "Did not find overrider!");
145
146 return OverridersMap.lookup(Val: std::make_pair(x&: MD, y&: BaseOffset));
147 }
148
149 /// dump - dump the final overriders.
150 void dump() {
151 VisitedVirtualBasesSetTy VisitedVirtualBases;
152 dump(Out&: llvm::errs(), Base: BaseSubobject(MostDerivedClass, CharUnits::Zero()),
153 VisitedVirtualBases);
154 }
155
156};
157
158FinalOverriders::FinalOverriders(const CXXRecordDecl *MostDerivedClass,
159 CharUnits MostDerivedClassOffset,
160 const CXXRecordDecl *LayoutClass)
161 : MostDerivedClass(MostDerivedClass),
162 MostDerivedClassOffset(MostDerivedClassOffset), LayoutClass(LayoutClass),
163 Context(MostDerivedClass->getASTContext()),
164 MostDerivedClassLayout(Context.getASTRecordLayout(D: MostDerivedClass)) {
165
166 // Compute base offsets.
167 SubobjectOffsetMapTy SubobjectOffsets;
168 SubobjectOffsetMapTy SubobjectLayoutClassOffsets;
169 SubobjectCountMapTy SubobjectCounts;
170 ComputeBaseOffsets(Base: BaseSubobject(MostDerivedClass, CharUnits::Zero()),
171 /*IsVirtual=*/false,
172 OffsetInLayoutClass: MostDerivedClassOffset,
173 SubobjectOffsets, SubobjectLayoutClassOffsets,
174 SubobjectCounts);
175
176 // Get the final overriders.
177 CXXFinalOverriderMap FinalOverriders;
178 MostDerivedClass->getFinalOverriders(FinaOverriders&: FinalOverriders);
179
180 for (const auto &Overrider : FinalOverriders) {
181 const CXXMethodDecl *MD = Overrider.first;
182 const OverridingMethods &Methods = Overrider.second;
183
184 for (const auto &M : Methods) {
185 unsigned SubobjectNumber = M.first;
186 assert(SubobjectOffsets.count(std::make_pair(MD->getParent(),
187 SubobjectNumber)) &&
188 "Did not find subobject offset!");
189
190 CharUnits BaseOffset = SubobjectOffsets[std::make_pair(x: MD->getParent(),
191 y&: SubobjectNumber)];
192
193 assert(M.second.size() == 1 && "Final overrider is not unique!");
194 const UniqueVirtualMethod &Method = M.second.front();
195
196 const CXXRecordDecl *OverriderRD = Method.Method->getParent();
197 assert(SubobjectLayoutClassOffsets.count(
198 std::make_pair(OverriderRD, Method.Subobject))
199 && "Did not find subobject offset!");
200 CharUnits OverriderOffset =
201 SubobjectLayoutClassOffsets[std::make_pair(x&: OverriderRD,
202 y: Method.Subobject)];
203
204 OverriderInfo& Overrider = OverridersMap[std::make_pair(x&: MD, y&: BaseOffset)];
205 assert(!Overrider.Method && "Overrider should not exist yet!");
206
207 Overrider.Offset = OverriderOffset;
208 Overrider.Method = Method.Method;
209 Overrider.VirtualBase = Method.InVirtualSubobject;
210 }
211 }
212
213#if DUMP_OVERRIDERS
214 // And dump them (for now).
215 dump();
216#endif
217}
218
219static BaseOffset ComputeBaseOffset(const ASTContext &Context,
220 const CXXRecordDecl *DerivedRD,
221 const CXXBasePath &Path) {
222 CharUnits NonVirtualOffset = CharUnits::Zero();
223
224 unsigned NonVirtualStart = 0;
225 const CXXRecordDecl *VirtualBase = nullptr;
226
227 // First, look for the virtual base class.
228 for (int I = Path.size(), E = 0; I != E; --I) {
229 const CXXBasePathElement &Element = Path[I - 1];
230
231 if (Element.Base->isVirtual()) {
232 NonVirtualStart = I;
233 QualType VBaseType = Element.Base->getType();
234 VirtualBase = VBaseType->getAsCXXRecordDecl();
235 break;
236 }
237 }
238
239 // Now compute the non-virtual offset.
240 for (unsigned I = NonVirtualStart, E = Path.size(); I != E; ++I) {
241 const CXXBasePathElement &Element = Path[I];
242
243 // Check the base class offset.
244 const ASTRecordLayout &Layout = Context.getASTRecordLayout(D: Element.Class);
245
246 const CXXRecordDecl *Base = Element.Base->getType()->getAsCXXRecordDecl();
247
248 NonVirtualOffset += Layout.getBaseClassOffset(Base);
249 }
250
251 // FIXME: This should probably use CharUnits or something. Maybe we should
252 // even change the base offsets in ASTRecordLayout to be specified in
253 // CharUnits.
254 return BaseOffset(DerivedRD, VirtualBase, NonVirtualOffset);
255
256}
257
258static BaseOffset ComputeBaseOffset(const ASTContext &Context,
259 const CXXRecordDecl *BaseRD,
260 const CXXRecordDecl *DerivedRD) {
261 CXXBasePaths Paths(/*FindAmbiguities=*/false,
262 /*RecordPaths=*/true, /*DetectVirtual=*/false);
263
264 if (!DerivedRD->isDerivedFrom(Base: BaseRD, Paths))
265 llvm_unreachable("Class must be derived from the passed in base class!");
266
267 return ComputeBaseOffset(Context, DerivedRD, Path: Paths.front());
268}
269
270static BaseOffset
271ComputeReturnAdjustmentBaseOffset(ASTContext &Context,
272 const CXXMethodDecl *DerivedMD,
273 const CXXMethodDecl *BaseMD) {
274 const auto *BaseFT = BaseMD->getType()->castAs<FunctionType>();
275 const auto *DerivedFT = DerivedMD->getType()->castAs<FunctionType>();
276
277 // Canonicalize the return types.
278 CanQualType CanDerivedReturnType =
279 Context.getCanonicalType(T: DerivedFT->getReturnType());
280 CanQualType CanBaseReturnType =
281 Context.getCanonicalType(T: BaseFT->getReturnType());
282
283 assert(CanDerivedReturnType->getTypeClass() ==
284 CanBaseReturnType->getTypeClass() &&
285 "Types must have same type class!");
286
287 if (CanDerivedReturnType == CanBaseReturnType) {
288 // No adjustment needed.
289 return BaseOffset();
290 }
291
292 if (isa<ReferenceType>(Val: CanDerivedReturnType)) {
293 CanDerivedReturnType =
294 CanDerivedReturnType->getAs<ReferenceType>()->getPointeeType();
295 CanBaseReturnType =
296 CanBaseReturnType->getAs<ReferenceType>()->getPointeeType();
297 } else if (isa<PointerType>(Val: CanDerivedReturnType)) {
298 CanDerivedReturnType =
299 CanDerivedReturnType->getAs<PointerType>()->getPointeeType();
300 CanBaseReturnType =
301 CanBaseReturnType->getAs<PointerType>()->getPointeeType();
302 } else {
303 llvm_unreachable("Unexpected return type!");
304 }
305
306 // We need to compare unqualified types here; consider
307 // const T *Base::foo();
308 // T *Derived::foo();
309 if (CanDerivedReturnType.getUnqualifiedType() ==
310 CanBaseReturnType.getUnqualifiedType()) {
311 // No adjustment needed.
312 return BaseOffset();
313 }
314
315 const CXXRecordDecl *DerivedRD =
316 cast<CXXRecordDecl>(Val: cast<RecordType>(Val&: CanDerivedReturnType)->getDecl());
317
318 const CXXRecordDecl *BaseRD =
319 cast<CXXRecordDecl>(Val: cast<RecordType>(Val&: CanBaseReturnType)->getDecl());
320
321 return ComputeBaseOffset(Context, BaseRD, DerivedRD);
322}
323
324void
325FinalOverriders::ComputeBaseOffsets(BaseSubobject Base, bool IsVirtual,
326 CharUnits OffsetInLayoutClass,
327 SubobjectOffsetMapTy &SubobjectOffsets,
328 SubobjectOffsetMapTy &SubobjectLayoutClassOffsets,
329 SubobjectCountMapTy &SubobjectCounts) {
330 const CXXRecordDecl *RD = Base.getBase();
331
332 unsigned SubobjectNumber = 0;
333 if (!IsVirtual)
334 SubobjectNumber = ++SubobjectCounts[RD];
335
336 // Set up the subobject to offset mapping.
337 assert(!SubobjectOffsets.count(std::make_pair(RD, SubobjectNumber))
338 && "Subobject offset already exists!");
339 assert(!SubobjectLayoutClassOffsets.count(std::make_pair(RD, SubobjectNumber))
340 && "Subobject offset already exists!");
341
342 SubobjectOffsets[std::make_pair(x&: RD, y&: SubobjectNumber)] = Base.getBaseOffset();
343 SubobjectLayoutClassOffsets[std::make_pair(x&: RD, y&: SubobjectNumber)] =
344 OffsetInLayoutClass;
345
346 // Traverse our bases.
347 for (const auto &B : RD->bases()) {
348 const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
349
350 CharUnits BaseOffset;
351 CharUnits BaseOffsetInLayoutClass;
352 if (B.isVirtual()) {
353 // Check if we've visited this virtual base before.
354 if (SubobjectOffsets.count(Val: std::make_pair(x&: BaseDecl, y: 0)))
355 continue;
356
357 const ASTRecordLayout &LayoutClassLayout =
358 Context.getASTRecordLayout(D: LayoutClass);
359
360 BaseOffset = MostDerivedClassLayout.getVBaseClassOffset(VBase: BaseDecl);
361 BaseOffsetInLayoutClass =
362 LayoutClassLayout.getVBaseClassOffset(VBase: BaseDecl);
363 } else {
364 const ASTRecordLayout &Layout = Context.getASTRecordLayout(D: RD);
365 CharUnits Offset = Layout.getBaseClassOffset(Base: BaseDecl);
366
367 BaseOffset = Base.getBaseOffset() + Offset;
368 BaseOffsetInLayoutClass = OffsetInLayoutClass + Offset;
369 }
370
371 ComputeBaseOffsets(Base: BaseSubobject(BaseDecl, BaseOffset),
372 IsVirtual: B.isVirtual(), OffsetInLayoutClass: BaseOffsetInLayoutClass,
373 SubobjectOffsets, SubobjectLayoutClassOffsets,
374 SubobjectCounts);
375 }
376}
377
378void FinalOverriders::dump(raw_ostream &Out, BaseSubobject Base,
379 VisitedVirtualBasesSetTy &VisitedVirtualBases) {
380 const CXXRecordDecl *RD = Base.getBase();
381 const ASTRecordLayout &Layout = Context.getASTRecordLayout(D: RD);
382
383 for (const auto &B : RD->bases()) {
384 const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
385
386 // Ignore bases that don't have any virtual member functions.
387 if (!BaseDecl->isPolymorphic())
388 continue;
389
390 CharUnits BaseOffset;
391 if (B.isVirtual()) {
392 if (!VisitedVirtualBases.insert(Ptr: BaseDecl).second) {
393 // We've visited this base before.
394 continue;
395 }
396
397 BaseOffset = MostDerivedClassLayout.getVBaseClassOffset(VBase: BaseDecl);
398 } else {
399 BaseOffset = Layout.getBaseClassOffset(Base: BaseDecl) + Base.getBaseOffset();
400 }
401
402 dump(Out, Base: BaseSubobject(BaseDecl, BaseOffset), VisitedVirtualBases);
403 }
404
405 Out << "Final overriders for (";
406 RD->printQualifiedName(OS&: Out);
407 Out << ", ";
408 Out << Base.getBaseOffset().getQuantity() << ")\n";
409
410 // Now dump the overriders for this base subobject.
411 for (const auto *MD : RD->methods()) {
412 if (!VTableContextBase::hasVtableSlot(MD))
413 continue;
414 MD = MD->getCanonicalDecl();
415
416 OverriderInfo Overrider = getOverrider(MD, BaseOffset: Base.getBaseOffset());
417
418 Out << " ";
419 MD->printQualifiedName(OS&: Out);
420 Out << " - (";
421 Overrider.Method->printQualifiedName(OS&: Out);
422 Out << ", " << Overrider.Offset.getQuantity() << ')';
423
424 BaseOffset Offset;
425 if (!Overrider.Method->isPureVirtual())
426 Offset = ComputeReturnAdjustmentBaseOffset(Context, DerivedMD: Overrider.Method, BaseMD: MD);
427
428 if (!Offset.isEmpty()) {
429 Out << " [ret-adj: ";
430 if (Offset.VirtualBase) {
431 Offset.VirtualBase->printQualifiedName(OS&: Out);
432 Out << " vbase, ";
433 }
434
435 Out << Offset.NonVirtualOffset.getQuantity() << " nv]";
436 }
437
438 Out << "\n";
439 }
440}
441
442/// VCallOffsetMap - Keeps track of vcall offsets when building a vtable.
443struct VCallOffsetMap {
444
445 typedef std::pair<const CXXMethodDecl *, CharUnits> MethodAndOffsetPairTy;
446
447 /// Offsets - Keeps track of methods and their offsets.
448 // FIXME: This should be a real map and not a vector.
449 SmallVector<MethodAndOffsetPairTy, 16> Offsets;
450
451 /// MethodsCanShareVCallOffset - Returns whether two virtual member functions
452 /// can share the same vcall offset.
453 static bool MethodsCanShareVCallOffset(const CXXMethodDecl *LHS,
454 const CXXMethodDecl *RHS);
455
456public:
457 /// AddVCallOffset - Adds a vcall offset to the map. Returns true if the
458 /// add was successful, or false if there was already a member function with
459 /// the same signature in the map.
460 bool AddVCallOffset(const CXXMethodDecl *MD, CharUnits OffsetOffset);
461
462 /// getVCallOffsetOffset - Returns the vcall offset offset (relative to the
463 /// vtable address point) for the given virtual member function.
464 CharUnits getVCallOffsetOffset(const CXXMethodDecl *MD);
465
466 // empty - Return whether the offset map is empty or not.
467 bool empty() const { return Offsets.empty(); }
468};
469
470static bool HasSameVirtualSignature(const CXXMethodDecl *LHS,
471 const CXXMethodDecl *RHS) {
472 const FunctionProtoType *LT =
473 cast<FunctionProtoType>(Val: LHS->getType().getCanonicalType());
474 const FunctionProtoType *RT =
475 cast<FunctionProtoType>(Val: RHS->getType().getCanonicalType());
476
477 // Fast-path matches in the canonical types.
478 if (LT == RT) return true;
479
480 // Force the signatures to match. We can't rely on the overrides
481 // list here because there isn't necessarily an inheritance
482 // relationship between the two methods.
483 if (LT->getMethodQuals() != RT->getMethodQuals())
484 return false;
485 return LT->getParamTypes() == RT->getParamTypes();
486}
487
488bool VCallOffsetMap::MethodsCanShareVCallOffset(const CXXMethodDecl *LHS,
489 const CXXMethodDecl *RHS) {
490 assert(VTableContextBase::hasVtableSlot(LHS) && "LHS must be virtual!");
491 assert(VTableContextBase::hasVtableSlot(RHS) && "RHS must be virtual!");
492
493 // A destructor can share a vcall offset with another destructor.
494 if (isa<CXXDestructorDecl>(Val: LHS))
495 return isa<CXXDestructorDecl>(Val: RHS);
496
497 // FIXME: We need to check more things here.
498
499 // The methods must have the same name.
500 DeclarationName LHSName = LHS->getDeclName();
501 DeclarationName RHSName = RHS->getDeclName();
502 if (LHSName != RHSName)
503 return false;
504
505 // And the same signatures.
506 return HasSameVirtualSignature(LHS, RHS);
507}
508
509bool VCallOffsetMap::AddVCallOffset(const CXXMethodDecl *MD,
510 CharUnits OffsetOffset) {
511 // Check if we can reuse an offset.
512 for (const auto &OffsetPair : Offsets) {
513 if (MethodsCanShareVCallOffset(LHS: OffsetPair.first, RHS: MD))
514 return false;
515 }
516
517 // Add the offset.
518 Offsets.push_back(Elt: MethodAndOffsetPairTy(MD, OffsetOffset));
519 return true;
520}
521
522CharUnits VCallOffsetMap::getVCallOffsetOffset(const CXXMethodDecl *MD) {
523 // Look for an offset.
524 for (const auto &OffsetPair : Offsets) {
525 if (MethodsCanShareVCallOffset(LHS: OffsetPair.first, RHS: MD))
526 return OffsetPair.second;
527 }
528
529 llvm_unreachable("Should always find a vcall offset offset!");
530}
531
532/// VCallAndVBaseOffsetBuilder - Class for building vcall and vbase offsets.
533class VCallAndVBaseOffsetBuilder {
534public:
535 typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits>
536 VBaseOffsetOffsetsMapTy;
537
538private:
539 const ItaniumVTableContext &VTables;
540
541 /// MostDerivedClass - The most derived class for which we're building vcall
542 /// and vbase offsets.
543 const CXXRecordDecl *MostDerivedClass;
544
545 /// LayoutClass - The class we're using for layout information. Will be
546 /// different than the most derived class if we're building a construction
547 /// vtable.
548 const CXXRecordDecl *LayoutClass;
549
550 /// Context - The ASTContext which we will use for layout information.
551 ASTContext &Context;
552
553 /// Components - vcall and vbase offset components
554 typedef SmallVector<VTableComponent, 64> VTableComponentVectorTy;
555 VTableComponentVectorTy Components;
556
557 /// VisitedVirtualBases - Visited virtual bases.
558 llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBases;
559
560 /// VCallOffsets - Keeps track of vcall offsets.
561 VCallOffsetMap VCallOffsets;
562
563
564 /// VBaseOffsetOffsets - Contains the offsets of the virtual base offsets,
565 /// relative to the address point.
566 VBaseOffsetOffsetsMapTy VBaseOffsetOffsets;
567
568 /// FinalOverriders - The final overriders of the most derived class.
569 /// (Can be null when we're not building a vtable of the most derived class).
570 const FinalOverriders *Overriders;
571
572 /// AddVCallAndVBaseOffsets - Add vcall offsets and vbase offsets for the
573 /// given base subobject.
574 void AddVCallAndVBaseOffsets(BaseSubobject Base, bool BaseIsVirtual,
575 CharUnits RealBaseOffset);
576
577 /// AddVCallOffsets - Add vcall offsets for the given base subobject.
578 void AddVCallOffsets(BaseSubobject Base, CharUnits VBaseOffset);
579
580 /// AddVBaseOffsets - Add vbase offsets for the given class.
581 void AddVBaseOffsets(const CXXRecordDecl *Base,
582 CharUnits OffsetInLayoutClass);
583
584 /// getCurrentOffsetOffset - Get the current vcall or vbase offset offset in
585 /// chars, relative to the vtable address point.
586 CharUnits getCurrentOffsetOffset() const;
587
588public:
589 VCallAndVBaseOffsetBuilder(const ItaniumVTableContext &VTables,
590 const CXXRecordDecl *MostDerivedClass,
591 const CXXRecordDecl *LayoutClass,
592 const FinalOverriders *Overriders,
593 BaseSubobject Base, bool BaseIsVirtual,
594 CharUnits OffsetInLayoutClass)
595 : VTables(VTables), MostDerivedClass(MostDerivedClass),
596 LayoutClass(LayoutClass), Context(MostDerivedClass->getASTContext()),
597 Overriders(Overriders) {
598
599 // Add vcall and vbase offsets.
600 AddVCallAndVBaseOffsets(Base, BaseIsVirtual, RealBaseOffset: OffsetInLayoutClass);
601 }
602
603 /// Methods for iterating over the components.
604 typedef VTableComponentVectorTy::const_reverse_iterator const_iterator;
605 const_iterator components_begin() const { return Components.rbegin(); }
606 const_iterator components_end() const { return Components.rend(); }
607
608 const VCallOffsetMap &getVCallOffsets() const { return VCallOffsets; }
609 const VBaseOffsetOffsetsMapTy &getVBaseOffsetOffsets() const {
610 return VBaseOffsetOffsets;
611 }
612};
613
614void
615VCallAndVBaseOffsetBuilder::AddVCallAndVBaseOffsets(BaseSubobject Base,
616 bool BaseIsVirtual,
617 CharUnits RealBaseOffset) {
618 const ASTRecordLayout &Layout = Context.getASTRecordLayout(D: Base.getBase());
619
620 // Itanium C++ ABI 2.5.2:
621 // ..in classes sharing a virtual table with a primary base class, the vcall
622 // and vbase offsets added by the derived class all come before the vcall
623 // and vbase offsets required by the base class, so that the latter may be
624 // laid out as required by the base class without regard to additions from
625 // the derived class(es).
626
627 // (Since we're emitting the vcall and vbase offsets in reverse order, we'll
628 // emit them for the primary base first).
629 if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
630 bool PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual();
631
632 CharUnits PrimaryBaseOffset;
633
634 // Get the base offset of the primary base.
635 if (PrimaryBaseIsVirtual) {
636 assert(Layout.getVBaseClassOffset(PrimaryBase).isZero() &&
637 "Primary vbase should have a zero offset!");
638
639 const ASTRecordLayout &MostDerivedClassLayout =
640 Context.getASTRecordLayout(D: MostDerivedClass);
641
642 PrimaryBaseOffset =
643 MostDerivedClassLayout.getVBaseClassOffset(VBase: PrimaryBase);
644 } else {
645 assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
646 "Primary base should have a zero offset!");
647
648 PrimaryBaseOffset = Base.getBaseOffset();
649 }
650
651 AddVCallAndVBaseOffsets(
652 Base: BaseSubobject(PrimaryBase,PrimaryBaseOffset),
653 BaseIsVirtual: PrimaryBaseIsVirtual, RealBaseOffset);
654 }
655
656 AddVBaseOffsets(Base: Base.getBase(), OffsetInLayoutClass: RealBaseOffset);
657
658 // We only want to add vcall offsets for virtual bases.
659 if (BaseIsVirtual)
660 AddVCallOffsets(Base, VBaseOffset: RealBaseOffset);
661}
662
663CharUnits VCallAndVBaseOffsetBuilder::getCurrentOffsetOffset() const {
664 // OffsetIndex is the index of this vcall or vbase offset, relative to the
665 // vtable address point. (We subtract 3 to account for the information just
666 // above the address point, the RTTI info, the offset to top, and the
667 // vcall offset itself).
668 size_t NumComponentsAboveAddrPoint = 3;
669 if (Context.getLangOpts().OmitVTableRTTI)
670 NumComponentsAboveAddrPoint--;
671 int64_t OffsetIndex =
672 -(int64_t)(NumComponentsAboveAddrPoint + Components.size());
673
674 // Under the relative ABI, the offset widths are 32-bit ints instead of
675 // pointer widths.
676 CharUnits OffsetWidth = Context.toCharUnitsFromBits(
677 BitSize: VTables.isRelativeLayout()
678 ? 32
679 : Context.getTargetInfo().getPointerWidth(AddrSpace: LangAS::Default));
680 CharUnits OffsetOffset = OffsetWidth * OffsetIndex;
681
682 return OffsetOffset;
683}
684
685void VCallAndVBaseOffsetBuilder::AddVCallOffsets(BaseSubobject Base,
686 CharUnits VBaseOffset) {
687 const CXXRecordDecl *RD = Base.getBase();
688 const ASTRecordLayout &Layout = Context.getASTRecordLayout(D: RD);
689
690 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
691
692 // Handle the primary base first.
693 // We only want to add vcall offsets if the base is non-virtual; a virtual
694 // primary base will have its vcall and vbase offsets emitted already.
695 if (PrimaryBase && !Layout.isPrimaryBaseVirtual()) {
696 // Get the base offset of the primary base.
697 assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
698 "Primary base should have a zero offset!");
699
700 AddVCallOffsets(Base: BaseSubobject(PrimaryBase, Base.getBaseOffset()),
701 VBaseOffset);
702 }
703
704 // Add the vcall offsets.
705 for (const auto *MD : RD->methods()) {
706 if (!VTableContextBase::hasVtableSlot(MD))
707 continue;
708 MD = MD->getCanonicalDecl();
709
710 CharUnits OffsetOffset = getCurrentOffsetOffset();
711
712 // Don't add a vcall offset if we already have one for this member function
713 // signature.
714 if (!VCallOffsets.AddVCallOffset(MD, OffsetOffset))
715 continue;
716
717 CharUnits Offset = CharUnits::Zero();
718
719 if (Overriders) {
720 // Get the final overrider.
721 FinalOverriders::OverriderInfo Overrider =
722 Overriders->getOverrider(MD, BaseOffset: Base.getBaseOffset());
723
724 /// The vcall offset is the offset from the virtual base to the object
725 /// where the function was overridden.
726 Offset = Overrider.Offset - VBaseOffset;
727 }
728
729 Components.push_back(
730 Elt: VTableComponent::MakeVCallOffset(Offset));
731 }
732
733 // And iterate over all non-virtual bases (ignoring the primary base).
734 for (const auto &B : RD->bases()) {
735 if (B.isVirtual())
736 continue;
737
738 const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
739 if (BaseDecl == PrimaryBase)
740 continue;
741
742 // Get the base offset of this base.
743 CharUnits BaseOffset = Base.getBaseOffset() +
744 Layout.getBaseClassOffset(Base: BaseDecl);
745
746 AddVCallOffsets(Base: BaseSubobject(BaseDecl, BaseOffset),
747 VBaseOffset);
748 }
749}
750
751void
752VCallAndVBaseOffsetBuilder::AddVBaseOffsets(const CXXRecordDecl *RD,
753 CharUnits OffsetInLayoutClass) {
754 const ASTRecordLayout &LayoutClassLayout =
755 Context.getASTRecordLayout(D: LayoutClass);
756
757 // Add vbase offsets.
758 for (const auto &B : RD->bases()) {
759 const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
760
761 // Check if this is a virtual base that we haven't visited before.
762 if (B.isVirtual() && VisitedVirtualBases.insert(Ptr: BaseDecl).second) {
763 CharUnits Offset =
764 LayoutClassLayout.getVBaseClassOffset(VBase: BaseDecl) - OffsetInLayoutClass;
765
766 // Add the vbase offset offset.
767 assert(!VBaseOffsetOffsets.count(BaseDecl) &&
768 "vbase offset offset already exists!");
769
770 CharUnits VBaseOffsetOffset = getCurrentOffsetOffset();
771 VBaseOffsetOffsets.insert(
772 KV: std::make_pair(x&: BaseDecl, y&: VBaseOffsetOffset));
773
774 Components.push_back(
775 Elt: VTableComponent::MakeVBaseOffset(Offset));
776 }
777
778 // Check the base class looking for more vbase offsets.
779 AddVBaseOffsets(RD: BaseDecl, OffsetInLayoutClass);
780 }
781}
782
783/// ItaniumVTableBuilder - Class for building vtable layout information.
784class ItaniumVTableBuilder {
785public:
786 /// PrimaryBasesSetVectorTy - A set vector of direct and indirect
787 /// primary bases.
788 typedef llvm::SmallSetVector<const CXXRecordDecl *, 8>
789 PrimaryBasesSetVectorTy;
790
791 typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits>
792 VBaseOffsetOffsetsMapTy;
793
794 typedef VTableLayout::AddressPointsMapTy AddressPointsMapTy;
795
796 typedef llvm::DenseMap<GlobalDecl, int64_t> MethodVTableIndicesTy;
797
798private:
799 /// VTables - Global vtable information.
800 ItaniumVTableContext &VTables;
801
802 /// MostDerivedClass - The most derived class for which we're building this
803 /// vtable.
804 const CXXRecordDecl *MostDerivedClass;
805
806 /// MostDerivedClassOffset - If we're building a construction vtable, this
807 /// holds the offset from the layout class to the most derived class.
808 const CharUnits MostDerivedClassOffset;
809
810 /// MostDerivedClassIsVirtual - Whether the most derived class is a virtual
811 /// base. (This only makes sense when building a construction vtable).
812 bool MostDerivedClassIsVirtual;
813
814 /// LayoutClass - The class we're using for layout information. Will be
815 /// different than the most derived class if we're building a construction
816 /// vtable.
817 const CXXRecordDecl *LayoutClass;
818
819 /// Context - The ASTContext which we will use for layout information.
820 ASTContext &Context;
821
822 /// FinalOverriders - The final overriders of the most derived class.
823 const FinalOverriders Overriders;
824
825 /// VCallOffsetsForVBases - Keeps track of vcall offsets for the virtual
826 /// bases in this vtable.
827 llvm::DenseMap<const CXXRecordDecl *, VCallOffsetMap> VCallOffsetsForVBases;
828
829 /// VBaseOffsetOffsets - Contains the offsets of the virtual base offsets for
830 /// the most derived class.
831 VBaseOffsetOffsetsMapTy VBaseOffsetOffsets;
832
833 /// Components - The components of the vtable being built.
834 SmallVector<VTableComponent, 64> Components;
835
836 /// AddressPoints - Address points for the vtable being built.
837 AddressPointsMapTy AddressPoints;
838
839 /// MethodInfo - Contains information about a method in a vtable.
840 /// (Used for computing 'this' pointer adjustment thunks.
841 struct MethodInfo {
842 /// BaseOffset - The base offset of this method.
843 const CharUnits BaseOffset;
844
845 /// BaseOffsetInLayoutClass - The base offset in the layout class of this
846 /// method.
847 const CharUnits BaseOffsetInLayoutClass;
848
849 /// VTableIndex - The index in the vtable that this method has.
850 /// (For destructors, this is the index of the complete destructor).
851 const uint64_t VTableIndex;
852
853 MethodInfo(CharUnits BaseOffset, CharUnits BaseOffsetInLayoutClass,
854 uint64_t VTableIndex)
855 : BaseOffset(BaseOffset),
856 BaseOffsetInLayoutClass(BaseOffsetInLayoutClass),
857 VTableIndex(VTableIndex) { }
858
859 MethodInfo()
860 : BaseOffset(CharUnits::Zero()),
861 BaseOffsetInLayoutClass(CharUnits::Zero()),
862 VTableIndex(0) { }
863
864 MethodInfo(MethodInfo const&) = default;
865 };
866
867 typedef llvm::DenseMap<const CXXMethodDecl *, MethodInfo> MethodInfoMapTy;
868
869 /// MethodInfoMap - The information for all methods in the vtable we're
870 /// currently building.
871 MethodInfoMapTy MethodInfoMap;
872
873 /// MethodVTableIndices - Contains the index (relative to the vtable address
874 /// point) where the function pointer for a virtual function is stored.
875 MethodVTableIndicesTy MethodVTableIndices;
876
877 typedef llvm::DenseMap<uint64_t, ThunkInfo> VTableThunksMapTy;
878
879 /// VTableThunks - The thunks by vtable index in the vtable currently being
880 /// built.
881 VTableThunksMapTy VTableThunks;
882
883 typedef SmallVector<ThunkInfo, 1> ThunkInfoVectorTy;
884 typedef llvm::DenseMap<const CXXMethodDecl *, ThunkInfoVectorTy> ThunksMapTy;
885
886 /// Thunks - A map that contains all the thunks needed for all methods in the
887 /// most derived class for which the vtable is currently being built.
888 ThunksMapTy Thunks;
889
890 /// AddThunk - Add a thunk for the given method.
891 void AddThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk);
892
893 /// ComputeThisAdjustments - Compute the 'this' pointer adjustments for the
894 /// part of the vtable we're currently building.
895 void ComputeThisAdjustments();
896
897 typedef llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBasesSetTy;
898
899 /// PrimaryVirtualBases - All known virtual bases who are a primary base of
900 /// some other base.
901 VisitedVirtualBasesSetTy PrimaryVirtualBases;
902
903 /// ComputeReturnAdjustment - Compute the return adjustment given a return
904 /// adjustment base offset.
905 ReturnAdjustment ComputeReturnAdjustment(BaseOffset Offset);
906
907 /// ComputeThisAdjustmentBaseOffset - Compute the base offset for adjusting
908 /// the 'this' pointer from the base subobject to the derived subobject.
909 BaseOffset ComputeThisAdjustmentBaseOffset(BaseSubobject Base,
910 BaseSubobject Derived) const;
911
912 /// ComputeThisAdjustment - Compute the 'this' pointer adjustment for the
913 /// given virtual member function, its offset in the layout class and its
914 /// final overrider.
915 ThisAdjustment
916 ComputeThisAdjustment(const CXXMethodDecl *MD,
917 CharUnits BaseOffsetInLayoutClass,
918 FinalOverriders::OverriderInfo Overrider);
919
920 /// AddMethod - Add a single virtual member function to the vtable
921 /// components vector.
922 void AddMethod(const CXXMethodDecl *MD, ReturnAdjustment ReturnAdjustment);
923
924 /// IsOverriderUsed - Returns whether the overrider will ever be used in this
925 /// part of the vtable.
926 ///
927 /// Itanium C++ ABI 2.5.2:
928 ///
929 /// struct A { virtual void f(); };
930 /// struct B : virtual public A { int i; };
931 /// struct C : virtual public A { int j; };
932 /// struct D : public B, public C {};
933 ///
934 /// When B and C are declared, A is a primary base in each case, so although
935 /// vcall offsets are allocated in the A-in-B and A-in-C vtables, no this
936 /// adjustment is required and no thunk is generated. However, inside D
937 /// objects, A is no longer a primary base of C, so if we allowed calls to
938 /// C::f() to use the copy of A's vtable in the C subobject, we would need
939 /// to adjust this from C* to B::A*, which would require a third-party
940 /// thunk. Since we require that a call to C::f() first convert to A*,
941 /// C-in-D's copy of A's vtable is never referenced, so this is not
942 /// necessary.
943 bool IsOverriderUsed(const CXXMethodDecl *Overrider,
944 CharUnits BaseOffsetInLayoutClass,
945 const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
946 CharUnits FirstBaseOffsetInLayoutClass) const;
947
948
949 /// AddMethods - Add the methods of this base subobject and all its
950 /// primary bases to the vtable components vector.
951 void AddMethods(BaseSubobject Base, CharUnits BaseOffsetInLayoutClass,
952 const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
953 CharUnits FirstBaseOffsetInLayoutClass,
954 PrimaryBasesSetVectorTy &PrimaryBases);
955
956 // LayoutVTable - Layout the vtable for the given base class, including its
957 // secondary vtables and any vtables for virtual bases.
958 void LayoutVTable();
959
960 /// LayoutPrimaryAndSecondaryVTables - Layout the primary vtable for the
961 /// given base subobject, as well as all its secondary vtables.
962 ///
963 /// \param BaseIsMorallyVirtual whether the base subobject is a virtual base
964 /// or a direct or indirect base of a virtual base.
965 ///
966 /// \param BaseIsVirtualInLayoutClass - Whether the base subobject is virtual
967 /// in the layout class.
968 void LayoutPrimaryAndSecondaryVTables(BaseSubobject Base,
969 bool BaseIsMorallyVirtual,
970 bool BaseIsVirtualInLayoutClass,
971 CharUnits OffsetInLayoutClass);
972
973 /// LayoutSecondaryVTables - Layout the secondary vtables for the given base
974 /// subobject.
975 ///
976 /// \param BaseIsMorallyVirtual whether the base subobject is a virtual base
977 /// or a direct or indirect base of a virtual base.
978 void LayoutSecondaryVTables(BaseSubobject Base, bool BaseIsMorallyVirtual,
979 CharUnits OffsetInLayoutClass);
980
981 /// DeterminePrimaryVirtualBases - Determine the primary virtual bases in this
982 /// class hierarchy.
983 void DeterminePrimaryVirtualBases(const CXXRecordDecl *RD,
984 CharUnits OffsetInLayoutClass,
985 VisitedVirtualBasesSetTy &VBases);
986
987 /// LayoutVTablesForVirtualBases - Layout vtables for all virtual bases of the
988 /// given base (excluding any primary bases).
989 void LayoutVTablesForVirtualBases(const CXXRecordDecl *RD,
990 VisitedVirtualBasesSetTy &VBases);
991
992 /// isBuildingConstructionVTable - Return whether this vtable builder is
993 /// building a construction vtable.
994 bool isBuildingConstructorVTable() const {
995 return MostDerivedClass != LayoutClass;
996 }
997
998public:
999 /// Component indices of the first component of each of the vtables in the
1000 /// vtable group.
1001 SmallVector<size_t, 4> VTableIndices;
1002
1003 ItaniumVTableBuilder(ItaniumVTableContext &VTables,
1004 const CXXRecordDecl *MostDerivedClass,
1005 CharUnits MostDerivedClassOffset,
1006 bool MostDerivedClassIsVirtual,
1007 const CXXRecordDecl *LayoutClass)
1008 : VTables(VTables), MostDerivedClass(MostDerivedClass),
1009 MostDerivedClassOffset(MostDerivedClassOffset),
1010 MostDerivedClassIsVirtual(MostDerivedClassIsVirtual),
1011 LayoutClass(LayoutClass), Context(MostDerivedClass->getASTContext()),
1012 Overriders(MostDerivedClass, MostDerivedClassOffset, LayoutClass) {
1013 assert(!Context.getTargetInfo().getCXXABI().isMicrosoft());
1014
1015 LayoutVTable();
1016
1017 if (Context.getLangOpts().DumpVTableLayouts)
1018 dumpLayout(llvm::outs());
1019 }
1020
1021 uint64_t getNumThunks() const {
1022 return Thunks.size();
1023 }
1024
1025 ThunksMapTy::const_iterator thunks_begin() const {
1026 return Thunks.begin();
1027 }
1028
1029 ThunksMapTy::const_iterator thunks_end() const {
1030 return Thunks.end();
1031 }
1032
1033 const VBaseOffsetOffsetsMapTy &getVBaseOffsetOffsets() const {
1034 return VBaseOffsetOffsets;
1035 }
1036
1037 const AddressPointsMapTy &getAddressPoints() const {
1038 return AddressPoints;
1039 }
1040
1041 MethodVTableIndicesTy::const_iterator vtable_indices_begin() const {
1042 return MethodVTableIndices.begin();
1043 }
1044
1045 MethodVTableIndicesTy::const_iterator vtable_indices_end() const {
1046 return MethodVTableIndices.end();
1047 }
1048
1049 ArrayRef<VTableComponent> vtable_components() const { return Components; }
1050
1051 AddressPointsMapTy::const_iterator address_points_begin() const {
1052 return AddressPoints.begin();
1053 }
1054
1055 AddressPointsMapTy::const_iterator address_points_end() const {
1056 return AddressPoints.end();
1057 }
1058
1059 VTableThunksMapTy::const_iterator vtable_thunks_begin() const {
1060 return VTableThunks.begin();
1061 }
1062
1063 VTableThunksMapTy::const_iterator vtable_thunks_end() const {
1064 return VTableThunks.end();
1065 }
1066
1067 /// dumpLayout - Dump the vtable layout.
1068 void dumpLayout(raw_ostream&);
1069};
1070
1071void ItaniumVTableBuilder::AddThunk(const CXXMethodDecl *MD,
1072 const ThunkInfo &Thunk) {
1073 assert(!isBuildingConstructorVTable() &&
1074 "Can't add thunks for construction vtable");
1075
1076 SmallVectorImpl<ThunkInfo> &ThunksVector = Thunks[MD];
1077
1078 // Check if we have this thunk already.
1079 if (llvm::is_contained(Range&: ThunksVector, Element: Thunk))
1080 return;
1081
1082 ThunksVector.push_back(Elt: Thunk);
1083}
1084
1085typedef llvm::SmallPtrSet<const CXXMethodDecl *, 8> OverriddenMethodsSetTy;
1086
1087/// Visit all the methods overridden by the given method recursively,
1088/// in a depth-first pre-order. The Visitor's visitor method returns a bool
1089/// indicating whether to continue the recursion for the given overridden
1090/// method (i.e. returning false stops the iteration).
1091template <class VisitorTy>
1092static void
1093visitAllOverriddenMethods(const CXXMethodDecl *MD, VisitorTy &Visitor) {
1094 assert(VTableContextBase::hasVtableSlot(MD) && "Method is not virtual!");
1095
1096 for (const CXXMethodDecl *OverriddenMD : MD->overridden_methods()) {
1097 if (!Visitor(OverriddenMD))
1098 continue;
1099 visitAllOverriddenMethods(OverriddenMD, Visitor);
1100 }
1101}
1102
1103/// ComputeAllOverriddenMethods - Given a method decl, will return a set of all
1104/// the overridden methods that the function decl overrides.
1105static void
1106ComputeAllOverriddenMethods(const CXXMethodDecl *MD,
1107 OverriddenMethodsSetTy& OverriddenMethods) {
1108 auto OverriddenMethodsCollector = [&](const CXXMethodDecl *MD) {
1109 // Don't recurse on this method if we've already collected it.
1110 return OverriddenMethods.insert(Ptr: MD).second;
1111 };
1112 visitAllOverriddenMethods(MD, Visitor&: OverriddenMethodsCollector);
1113}
1114
1115void ItaniumVTableBuilder::ComputeThisAdjustments() {
1116 // Now go through the method info map and see if any of the methods need
1117 // 'this' pointer adjustments.
1118 for (const auto &MI : MethodInfoMap) {
1119 const CXXMethodDecl *MD = MI.first;
1120 const MethodInfo &MethodInfo = MI.second;
1121
1122 // Ignore adjustments for unused function pointers.
1123 uint64_t VTableIndex = MethodInfo.VTableIndex;
1124 if (Components[VTableIndex].getKind() ==
1125 VTableComponent::CK_UnusedFunctionPointer)
1126 continue;
1127
1128 // Get the final overrider for this method.
1129 FinalOverriders::OverriderInfo Overrider =
1130 Overriders.getOverrider(MD, BaseOffset: MethodInfo.BaseOffset);
1131
1132 // Check if we need an adjustment at all.
1133 if (MethodInfo.BaseOffsetInLayoutClass == Overrider.Offset) {
1134 // When a return thunk is needed by a derived class that overrides a
1135 // virtual base, gcc uses a virtual 'this' adjustment as well.
1136 // While the thunk itself might be needed by vtables in subclasses or
1137 // in construction vtables, there doesn't seem to be a reason for using
1138 // the thunk in this vtable. Still, we do so to match gcc.
1139 if (VTableThunks.lookup(Val: VTableIndex).Return.isEmpty())
1140 continue;
1141 }
1142
1143 ThisAdjustment ThisAdjustment =
1144 ComputeThisAdjustment(MD, BaseOffsetInLayoutClass: MethodInfo.BaseOffsetInLayoutClass, Overrider);
1145
1146 if (ThisAdjustment.isEmpty())
1147 continue;
1148
1149 // Add it.
1150 auto SetThisAdjustmentThunk = [&](uint64_t Idx) {
1151 // If a this pointer adjustment is required, record the method that
1152 // created the vtable entry. MD is not necessarily the method that
1153 // created the entry since derived classes overwrite base class
1154 // information in MethodInfoMap, hence findOriginalMethodInMap is called
1155 // here.
1156 //
1157 // For example, in the following class hierarchy, if MD = D1::m and
1158 // Overrider = D2:m, the original method that created the entry is B0:m,
1159 // which is what findOriginalMethodInMap(MD) returns:
1160 //
1161 // struct B0 { int a; virtual void m(); };
1162 // struct D0 : B0 { int a; void m() override; };
1163 // struct D1 : B0 { int a; void m() override; };
1164 // struct D2 : D0, D1 { int a; void m() override; };
1165 //
1166 // We need to record the method because we cannot
1167 // call findOriginalMethod to find the method that created the entry if
1168 // the method in the entry requires adjustment.
1169 //
1170 // Do not set ThunkInfo::Method if Idx is already in VTableThunks. This
1171 // can happen when covariant return adjustment is required too.
1172 auto [It, Inserted] = VTableThunks.try_emplace(Key: Idx);
1173 if (Inserted) {
1174 const CXXMethodDecl *Method = VTables.findOriginalMethodInMap(MD);
1175 It->second.Method = Method;
1176 It->second.ThisType = Method->getThisType().getTypePtr();
1177 }
1178 It->second.This = ThisAdjustment;
1179 };
1180
1181 SetThisAdjustmentThunk(VTableIndex);
1182
1183 if (isa<CXXDestructorDecl>(Val: MD)) {
1184 // Add an adjustment for the deleting destructor as well.
1185 SetThisAdjustmentThunk(VTableIndex + 1);
1186 }
1187 }
1188
1189 /// Clear the method info map.
1190 MethodInfoMap.clear();
1191
1192 if (isBuildingConstructorVTable()) {
1193 // We don't need to store thunk information for construction vtables.
1194 return;
1195 }
1196
1197 for (const auto &TI : VTableThunks) {
1198 const VTableComponent &Component = Components[TI.first];
1199 const ThunkInfo &Thunk = TI.second;
1200 const CXXMethodDecl *MD;
1201
1202 switch (Component.getKind()) {
1203 default:
1204 llvm_unreachable("Unexpected vtable component kind!");
1205 case VTableComponent::CK_FunctionPointer:
1206 MD = Component.getFunctionDecl();
1207 break;
1208 case VTableComponent::CK_CompleteDtorPointer:
1209 MD = Component.getDestructorDecl();
1210 break;
1211 case VTableComponent::CK_DeletingDtorPointer:
1212 // We've already added the thunk when we saw the complete dtor pointer.
1213 continue;
1214 }
1215
1216 if (MD->getParent() == MostDerivedClass)
1217 AddThunk(MD, Thunk);
1218 }
1219}
1220
1221ReturnAdjustment
1222ItaniumVTableBuilder::ComputeReturnAdjustment(BaseOffset Offset) {
1223 ReturnAdjustment Adjustment;
1224
1225 if (!Offset.isEmpty()) {
1226 if (Offset.VirtualBase) {
1227 // Get the virtual base offset offset.
1228 if (Offset.DerivedClass == MostDerivedClass) {
1229 // We can get the offset offset directly from our map.
1230 Adjustment.Virtual.Itanium.VBaseOffsetOffset =
1231 VBaseOffsetOffsets.lookup(Val: Offset.VirtualBase).getQuantity();
1232 } else {
1233 Adjustment.Virtual.Itanium.VBaseOffsetOffset =
1234 VTables.getVirtualBaseOffsetOffset(RD: Offset.DerivedClass,
1235 VBase: Offset.VirtualBase).getQuantity();
1236 }
1237 }
1238
1239 Adjustment.NonVirtual = Offset.NonVirtualOffset.getQuantity();
1240 }
1241
1242 return Adjustment;
1243}
1244
1245BaseOffset ItaniumVTableBuilder::ComputeThisAdjustmentBaseOffset(
1246 BaseSubobject Base, BaseSubobject Derived) const {
1247 const CXXRecordDecl *BaseRD = Base.getBase();
1248 const CXXRecordDecl *DerivedRD = Derived.getBase();
1249
1250 CXXBasePaths Paths(/*FindAmbiguities=*/true,
1251 /*RecordPaths=*/true, /*DetectVirtual=*/true);
1252
1253 if (!DerivedRD->isDerivedFrom(Base: BaseRD, Paths))
1254 llvm_unreachable("Class must be derived from the passed in base class!");
1255
1256 // We have to go through all the paths, and see which one leads us to the
1257 // right base subobject.
1258 for (const CXXBasePath &Path : Paths) {
1259 BaseOffset Offset = ComputeBaseOffset(Context, DerivedRD, Path);
1260
1261 CharUnits OffsetToBaseSubobject = Offset.NonVirtualOffset;
1262
1263 if (Offset.VirtualBase) {
1264 // If we have a virtual base class, the non-virtual offset is relative
1265 // to the virtual base class offset.
1266 const ASTRecordLayout &LayoutClassLayout =
1267 Context.getASTRecordLayout(D: LayoutClass);
1268
1269 /// Get the virtual base offset, relative to the most derived class
1270 /// layout.
1271 OffsetToBaseSubobject +=
1272 LayoutClassLayout.getVBaseClassOffset(VBase: Offset.VirtualBase);
1273 } else {
1274 // Otherwise, the non-virtual offset is relative to the derived class
1275 // offset.
1276 OffsetToBaseSubobject += Derived.getBaseOffset();
1277 }
1278
1279 // Check if this path gives us the right base subobject.
1280 if (OffsetToBaseSubobject == Base.getBaseOffset()) {
1281 // Since we're going from the base class _to_ the derived class, we'll
1282 // invert the non-virtual offset here.
1283 Offset.NonVirtualOffset = -Offset.NonVirtualOffset;
1284 return Offset;
1285 }
1286 }
1287
1288 return BaseOffset();
1289}
1290
1291ThisAdjustment ItaniumVTableBuilder::ComputeThisAdjustment(
1292 const CXXMethodDecl *MD, CharUnits BaseOffsetInLayoutClass,
1293 FinalOverriders::OverriderInfo Overrider) {
1294 // Ignore adjustments for pure virtual member functions.
1295 if (Overrider.Method->isPureVirtual())
1296 return ThisAdjustment();
1297
1298 BaseSubobject OverriddenBaseSubobject(MD->getParent(),
1299 BaseOffsetInLayoutClass);
1300
1301 BaseSubobject OverriderBaseSubobject(Overrider.Method->getParent(),
1302 Overrider.Offset);
1303
1304 // Compute the adjustment offset.
1305 BaseOffset Offset = ComputeThisAdjustmentBaseOffset(Base: OverriddenBaseSubobject,
1306 Derived: OverriderBaseSubobject);
1307 if (Offset.isEmpty())
1308 return ThisAdjustment();
1309
1310 ThisAdjustment Adjustment;
1311
1312 if (Offset.VirtualBase) {
1313 // Get the vcall offset map for this virtual base.
1314 VCallOffsetMap &VCallOffsets = VCallOffsetsForVBases[Offset.VirtualBase];
1315
1316 if (VCallOffsets.empty()) {
1317 // We don't have vcall offsets for this virtual base, go ahead and
1318 // build them.
1319 VCallAndVBaseOffsetBuilder Builder(
1320 VTables, MostDerivedClass, MostDerivedClass,
1321 /*Overriders=*/nullptr,
1322 BaseSubobject(Offset.VirtualBase, CharUnits::Zero()),
1323 /*BaseIsVirtual=*/true,
1324 /*OffsetInLayoutClass=*/
1325 CharUnits::Zero());
1326
1327 VCallOffsets = Builder.getVCallOffsets();
1328 }
1329
1330 Adjustment.Virtual.Itanium.VCallOffsetOffset =
1331 VCallOffsets.getVCallOffsetOffset(MD).getQuantity();
1332 }
1333
1334 // Set the non-virtual part of the adjustment.
1335 Adjustment.NonVirtual = Offset.NonVirtualOffset.getQuantity();
1336
1337 return Adjustment;
1338}
1339
1340void ItaniumVTableBuilder::AddMethod(const CXXMethodDecl *MD,
1341 ReturnAdjustment ReturnAdjustment) {
1342 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(Val: MD)) {
1343 assert(ReturnAdjustment.isEmpty() &&
1344 "Destructor can't have return adjustment!");
1345
1346 // Add both the complete destructor and the deleting destructor.
1347 Components.push_back(Elt: VTableComponent::MakeCompleteDtor(DD));
1348 Components.push_back(Elt: VTableComponent::MakeDeletingDtor(DD));
1349 } else {
1350 // Add the return adjustment if necessary.
1351 if (!ReturnAdjustment.isEmpty())
1352 VTableThunks[Components.size()].Return = ReturnAdjustment;
1353
1354 // Add the function.
1355 Components.push_back(Elt: VTableComponent::MakeFunction(MD));
1356 }
1357}
1358
1359/// OverridesIndirectMethodInBase - Return whether the given member function
1360/// overrides any methods in the set of given bases.
1361/// Unlike OverridesMethodInBase, this checks "overriders of overriders".
1362/// For example, if we have:
1363///
1364/// struct A { virtual void f(); }
1365/// struct B : A { virtual void f(); }
1366/// struct C : B { virtual void f(); }
1367///
1368/// OverridesIndirectMethodInBase will return true if given C::f as the method
1369/// and { A } as the set of bases.
1370static bool OverridesIndirectMethodInBases(
1371 const CXXMethodDecl *MD,
1372 ItaniumVTableBuilder::PrimaryBasesSetVectorTy &Bases) {
1373 if (Bases.count(key: MD->getParent()))
1374 return true;
1375
1376 for (const CXXMethodDecl *OverriddenMD : MD->overridden_methods()) {
1377 // Check "indirect overriders".
1378 if (OverridesIndirectMethodInBases(MD: OverriddenMD, Bases))
1379 return true;
1380 }
1381
1382 return false;
1383}
1384
1385bool ItaniumVTableBuilder::IsOverriderUsed(
1386 const CXXMethodDecl *Overrider, CharUnits BaseOffsetInLayoutClass,
1387 const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
1388 CharUnits FirstBaseOffsetInLayoutClass) const {
1389 // If the base and the first base in the primary base chain have the same
1390 // offsets, then this overrider will be used.
1391 if (BaseOffsetInLayoutClass == FirstBaseOffsetInLayoutClass)
1392 return true;
1393
1394 // We know now that Base (or a direct or indirect base of it) is a primary
1395 // base in part of the class hierarchy, but not a primary base in the most
1396 // derived class.
1397
1398 // If the overrider is the first base in the primary base chain, we know
1399 // that the overrider will be used.
1400 if (Overrider->getParent() == FirstBaseInPrimaryBaseChain)
1401 return true;
1402
1403 ItaniumVTableBuilder::PrimaryBasesSetVectorTy PrimaryBases;
1404
1405 const CXXRecordDecl *RD = FirstBaseInPrimaryBaseChain;
1406 PrimaryBases.insert(X: RD);
1407
1408 // Now traverse the base chain, starting with the first base, until we find
1409 // the base that is no longer a primary base.
1410 while (true) {
1411 const ASTRecordLayout &Layout = Context.getASTRecordLayout(D: RD);
1412 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
1413
1414 if (!PrimaryBase)
1415 break;
1416
1417 if (Layout.isPrimaryBaseVirtual()) {
1418 assert(Layout.getVBaseClassOffset(PrimaryBase).isZero() &&
1419 "Primary base should always be at offset 0!");
1420
1421 const ASTRecordLayout &LayoutClassLayout =
1422 Context.getASTRecordLayout(D: LayoutClass);
1423
1424 // Now check if this is the primary base that is not a primary base in the
1425 // most derived class.
1426 if (LayoutClassLayout.getVBaseClassOffset(VBase: PrimaryBase) !=
1427 FirstBaseOffsetInLayoutClass) {
1428 // We found it, stop walking the chain.
1429 break;
1430 }
1431 } else {
1432 assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
1433 "Primary base should always be at offset 0!");
1434 }
1435
1436 if (!PrimaryBases.insert(X: PrimaryBase))
1437 llvm_unreachable("Found a duplicate primary base!");
1438
1439 RD = PrimaryBase;
1440 }
1441
1442 // If the final overrider is an override of one of the primary bases,
1443 // then we know that it will be used.
1444 return OverridesIndirectMethodInBases(MD: Overrider, Bases&: PrimaryBases);
1445}
1446
1447typedef llvm::SmallSetVector<const CXXRecordDecl *, 8> BasesSetVectorTy;
1448
1449/// FindNearestOverriddenMethod - Given a method, returns the overridden method
1450/// from the nearest base. Returns null if no method was found.
1451/// The Bases are expected to be sorted in a base-to-derived order.
1452static const CXXMethodDecl *
1453FindNearestOverriddenMethod(const CXXMethodDecl *MD,
1454 BasesSetVectorTy &Bases) {
1455 OverriddenMethodsSetTy OverriddenMethods;
1456 ComputeAllOverriddenMethods(MD, OverriddenMethods);
1457
1458 for (const CXXRecordDecl *PrimaryBase : llvm::reverse(C&: Bases)) {
1459 // Now check the overridden methods.
1460 for (const CXXMethodDecl *OverriddenMD : OverriddenMethods) {
1461 // We found our overridden method.
1462 if (OverriddenMD->getParent() == PrimaryBase)
1463 return OverriddenMD;
1464 }
1465 }
1466
1467 return nullptr;
1468}
1469
1470void ItaniumVTableBuilder::AddMethods(
1471 BaseSubobject Base, CharUnits BaseOffsetInLayoutClass,
1472 const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
1473 CharUnits FirstBaseOffsetInLayoutClass,
1474 PrimaryBasesSetVectorTy &PrimaryBases) {
1475 // Itanium C++ ABI 2.5.2:
1476 // The order of the virtual function pointers in a virtual table is the
1477 // order of declaration of the corresponding member functions in the class.
1478 //
1479 // There is an entry for any virtual function declared in a class,
1480 // whether it is a new function or overrides a base class function,
1481 // unless it overrides a function from the primary base, and conversion
1482 // between their return types does not require an adjustment.
1483
1484 const CXXRecordDecl *RD = Base.getBase();
1485 const ASTRecordLayout &Layout = Context.getASTRecordLayout(D: RD);
1486
1487 if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
1488 CharUnits PrimaryBaseOffset;
1489 CharUnits PrimaryBaseOffsetInLayoutClass;
1490 if (Layout.isPrimaryBaseVirtual()) {
1491 assert(Layout.getVBaseClassOffset(PrimaryBase).isZero() &&
1492 "Primary vbase should have a zero offset!");
1493
1494 const ASTRecordLayout &MostDerivedClassLayout =
1495 Context.getASTRecordLayout(D: MostDerivedClass);
1496
1497 PrimaryBaseOffset =
1498 MostDerivedClassLayout.getVBaseClassOffset(VBase: PrimaryBase);
1499
1500 const ASTRecordLayout &LayoutClassLayout =
1501 Context.getASTRecordLayout(D: LayoutClass);
1502
1503 PrimaryBaseOffsetInLayoutClass =
1504 LayoutClassLayout.getVBaseClassOffset(VBase: PrimaryBase);
1505 } else {
1506 assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
1507 "Primary base should have a zero offset!");
1508
1509 PrimaryBaseOffset = Base.getBaseOffset();
1510 PrimaryBaseOffsetInLayoutClass = BaseOffsetInLayoutClass;
1511 }
1512
1513 AddMethods(Base: BaseSubobject(PrimaryBase, PrimaryBaseOffset),
1514 BaseOffsetInLayoutClass: PrimaryBaseOffsetInLayoutClass, FirstBaseInPrimaryBaseChain,
1515 FirstBaseOffsetInLayoutClass, PrimaryBases);
1516
1517 if (!PrimaryBases.insert(X: PrimaryBase))
1518 llvm_unreachable("Found a duplicate primary base!");
1519 }
1520
1521 typedef llvm::SmallVector<const CXXMethodDecl *, 8> NewVirtualFunctionsTy;
1522 NewVirtualFunctionsTy NewVirtualFunctions;
1523
1524 llvm::SmallVector<const CXXMethodDecl*, 4> NewImplicitVirtualFunctions;
1525
1526 // Now go through all virtual member functions and add them.
1527 for (const auto *MD : RD->methods()) {
1528 if (!ItaniumVTableContext::hasVtableSlot(MD))
1529 continue;
1530 MD = MD->getCanonicalDecl();
1531
1532 // Get the final overrider.
1533 FinalOverriders::OverriderInfo Overrider =
1534 Overriders.getOverrider(MD, BaseOffset: Base.getBaseOffset());
1535
1536 // Check if this virtual member function overrides a method in a primary
1537 // base. If this is the case, and the return type doesn't require adjustment
1538 // then we can just use the member function from the primary base.
1539 if (const CXXMethodDecl *OverriddenMD =
1540 FindNearestOverriddenMethod(MD, Bases&: PrimaryBases)) {
1541 if (ComputeReturnAdjustmentBaseOffset(Context, DerivedMD: MD,
1542 BaseMD: OverriddenMD).isEmpty()) {
1543 VTables.setOriginalMethod(Key: MD, Val: OverriddenMD);
1544
1545 // Replace the method info of the overridden method with our own
1546 // method.
1547 assert(MethodInfoMap.count(OverriddenMD) &&
1548 "Did not find the overridden method!");
1549 MethodInfo &OverriddenMethodInfo = MethodInfoMap[OverriddenMD];
1550
1551 MethodInfo MethodInfo(Base.getBaseOffset(), BaseOffsetInLayoutClass,
1552 OverriddenMethodInfo.VTableIndex);
1553
1554 assert(!MethodInfoMap.count(MD) &&
1555 "Should not have method info for this method yet!");
1556
1557 MethodInfoMap.insert(KV: std::make_pair(x&: MD, y&: MethodInfo));
1558 MethodInfoMap.erase(Val: OverriddenMD);
1559
1560 // If the overridden method exists in a virtual base class or a direct
1561 // or indirect base class of a virtual base class, we need to emit a
1562 // thunk if we ever have a class hierarchy where the base class is not
1563 // a primary base in the complete object.
1564 if (!isBuildingConstructorVTable() && OverriddenMD != MD) {
1565 // Compute the this adjustment.
1566 ThisAdjustment ThisAdjustment =
1567 ComputeThisAdjustment(MD: OverriddenMD, BaseOffsetInLayoutClass,
1568 Overrider);
1569
1570 if (ThisAdjustment.Virtual.Itanium.VCallOffsetOffset &&
1571 Overrider.Method->getParent() == MostDerivedClass) {
1572
1573 // There's no return adjustment from OverriddenMD and MD,
1574 // but that doesn't mean there isn't one between MD and
1575 // the final overrider.
1576 BaseOffset ReturnAdjustmentOffset =
1577 ComputeReturnAdjustmentBaseOffset(Context, DerivedMD: Overrider.Method, BaseMD: MD);
1578 ReturnAdjustment ReturnAdjustment =
1579 ComputeReturnAdjustment(Offset: ReturnAdjustmentOffset);
1580
1581 // This is a virtual thunk for the most derived class, add it.
1582 AddThunk(MD: Overrider.Method,
1583 Thunk: ThunkInfo(ThisAdjustment, ReturnAdjustment,
1584 OverriddenMD->getThisType().getTypePtr()));
1585 }
1586 }
1587
1588 continue;
1589 }
1590 }
1591
1592 if (MD->isImplicit())
1593 NewImplicitVirtualFunctions.push_back(Elt: MD);
1594 else
1595 NewVirtualFunctions.push_back(Elt: MD);
1596 }
1597
1598 llvm::stable_sort(
1599 Range&: NewImplicitVirtualFunctions,
1600 C: [](const CXXMethodDecl *A, const CXXMethodDecl *B) {
1601 if (A == B)
1602 return false;
1603 if (A->isCopyAssignmentOperator() != B->isCopyAssignmentOperator())
1604 return A->isCopyAssignmentOperator();
1605 if (A->isMoveAssignmentOperator() != B->isMoveAssignmentOperator())
1606 return A->isMoveAssignmentOperator();
1607 if (isa<CXXDestructorDecl>(Val: A) != isa<CXXDestructorDecl>(Val: B))
1608 return isa<CXXDestructorDecl>(Val: A);
1609 assert(A->getOverloadedOperator() == OO_EqualEqual &&
1610 B->getOverloadedOperator() == OO_EqualEqual &&
1611 "unexpected or duplicate implicit virtual function");
1612 // We rely on Sema to have declared the operator== members in the
1613 // same order as the corresponding operator<=> members.
1614 return false;
1615 });
1616 NewVirtualFunctions.append(in_start: NewImplicitVirtualFunctions.begin(),
1617 in_end: NewImplicitVirtualFunctions.end());
1618
1619 for (const CXXMethodDecl *MD : NewVirtualFunctions) {
1620 // Get the final overrider.
1621 FinalOverriders::OverriderInfo Overrider =
1622 Overriders.getOverrider(MD, BaseOffset: Base.getBaseOffset());
1623
1624 // Insert the method info for this method.
1625 MethodInfo MethodInfo(Base.getBaseOffset(), BaseOffsetInLayoutClass,
1626 Components.size());
1627
1628 assert(!MethodInfoMap.count(MD) &&
1629 "Should not have method info for this method yet!");
1630 MethodInfoMap.insert(KV: std::make_pair(x&: MD, y&: MethodInfo));
1631
1632 // Check if this overrider is going to be used.
1633 const CXXMethodDecl *OverriderMD = Overrider.Method;
1634 if (!IsOverriderUsed(Overrider: OverriderMD, BaseOffsetInLayoutClass,
1635 FirstBaseInPrimaryBaseChain,
1636 FirstBaseOffsetInLayoutClass)) {
1637 Components.push_back(Elt: VTableComponent::MakeUnusedFunction(MD: OverriderMD));
1638 continue;
1639 }
1640
1641 // Check if this overrider needs a return adjustment.
1642 // We don't want to do this for pure virtual member functions.
1643 BaseOffset ReturnAdjustmentOffset;
1644 if (!OverriderMD->isPureVirtual()) {
1645 ReturnAdjustmentOffset =
1646 ComputeReturnAdjustmentBaseOffset(Context, DerivedMD: OverriderMD, BaseMD: MD);
1647 }
1648
1649 ReturnAdjustment ReturnAdjustment =
1650 ComputeReturnAdjustment(Offset: ReturnAdjustmentOffset);
1651
1652 // If a return adjustment is required, record the method that created the
1653 // vtable entry. We need to record the method because we cannot call
1654 // findOriginalMethod to find the method that created the entry if the
1655 // method in the entry requires adjustment.
1656 if (!ReturnAdjustment.isEmpty()) {
1657 auto &VTT = VTableThunks[Components.size()];
1658 VTT.Method = MD;
1659 VTT.ThisType = MD->getThisType().getTypePtr();
1660 }
1661
1662 AddMethod(MD: Overrider.Method, ReturnAdjustment);
1663 }
1664}
1665
1666void ItaniumVTableBuilder::LayoutVTable() {
1667 LayoutPrimaryAndSecondaryVTables(Base: BaseSubobject(MostDerivedClass,
1668 CharUnits::Zero()),
1669 /*BaseIsMorallyVirtual=*/false,
1670 BaseIsVirtualInLayoutClass: MostDerivedClassIsVirtual,
1671 OffsetInLayoutClass: MostDerivedClassOffset);
1672
1673 VisitedVirtualBasesSetTy VBases;
1674
1675 // Determine the primary virtual bases.
1676 DeterminePrimaryVirtualBases(RD: MostDerivedClass, OffsetInLayoutClass: MostDerivedClassOffset,
1677 VBases);
1678 VBases.clear();
1679
1680 LayoutVTablesForVirtualBases(RD: MostDerivedClass, VBases);
1681
1682 // -fapple-kext adds an extra entry at end of vtbl.
1683 bool IsAppleKext = Context.getLangOpts().AppleKext;
1684 if (IsAppleKext)
1685 Components.push_back(Elt: VTableComponent::MakeVCallOffset(Offset: CharUnits::Zero()));
1686}
1687
1688void ItaniumVTableBuilder::LayoutPrimaryAndSecondaryVTables(
1689 BaseSubobject Base, bool BaseIsMorallyVirtual,
1690 bool BaseIsVirtualInLayoutClass, CharUnits OffsetInLayoutClass) {
1691 assert(Base.getBase()->isDynamicClass() && "class does not have a vtable!");
1692
1693 unsigned VTableIndex = Components.size();
1694 VTableIndices.push_back(Elt: VTableIndex);
1695
1696 // Add vcall and vbase offsets for this vtable.
1697 VCallAndVBaseOffsetBuilder Builder(
1698 VTables, MostDerivedClass, LayoutClass, &Overriders, Base,
1699 BaseIsVirtualInLayoutClass, OffsetInLayoutClass);
1700 Components.append(in_start: Builder.components_begin(), in_end: Builder.components_end());
1701
1702 // Check if we need to add these vcall offsets.
1703 if (BaseIsVirtualInLayoutClass && !Builder.getVCallOffsets().empty()) {
1704 VCallOffsetMap &VCallOffsets = VCallOffsetsForVBases[Base.getBase()];
1705
1706 if (VCallOffsets.empty())
1707 VCallOffsets = Builder.getVCallOffsets();
1708 }
1709
1710 // If we're laying out the most derived class we want to keep track of the
1711 // virtual base class offset offsets.
1712 if (Base.getBase() == MostDerivedClass)
1713 VBaseOffsetOffsets = Builder.getVBaseOffsetOffsets();
1714
1715 // Add the offset to top.
1716 CharUnits OffsetToTop = MostDerivedClassOffset - OffsetInLayoutClass;
1717 Components.push_back(Elt: VTableComponent::MakeOffsetToTop(Offset: OffsetToTop));
1718
1719 // Next, add the RTTI.
1720 if (!Context.getLangOpts().OmitVTableRTTI)
1721 Components.push_back(Elt: VTableComponent::MakeRTTI(RD: MostDerivedClass));
1722
1723 uint64_t AddressPoint = Components.size();
1724
1725 // Now go through all virtual member functions and add them.
1726 PrimaryBasesSetVectorTy PrimaryBases;
1727 AddMethods(Base, BaseOffsetInLayoutClass: OffsetInLayoutClass,
1728 FirstBaseInPrimaryBaseChain: Base.getBase(), FirstBaseOffsetInLayoutClass: OffsetInLayoutClass,
1729 PrimaryBases);
1730
1731 const CXXRecordDecl *RD = Base.getBase();
1732 if (RD == MostDerivedClass) {
1733 assert(MethodVTableIndices.empty());
1734 for (const auto &I : MethodInfoMap) {
1735 const CXXMethodDecl *MD = I.first;
1736 const MethodInfo &MI = I.second;
1737 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(Val: MD)) {
1738 MethodVTableIndices[GlobalDecl(DD, Dtor_Complete)]
1739 = MI.VTableIndex - AddressPoint;
1740 MethodVTableIndices[GlobalDecl(DD, Dtor_Deleting)]
1741 = MI.VTableIndex + 1 - AddressPoint;
1742 } else {
1743 MethodVTableIndices[MD] = MI.VTableIndex - AddressPoint;
1744 }
1745 }
1746 }
1747
1748 // Compute 'this' pointer adjustments.
1749 ComputeThisAdjustments();
1750
1751 // Add all address points.
1752 while (true) {
1753 AddressPoints.insert(
1754 KV: std::make_pair(x: BaseSubobject(RD, OffsetInLayoutClass),
1755 y: VTableLayout::AddressPointLocation{
1756 .VTableIndex: unsigned(VTableIndices.size() - 1),
1757 .AddressPointIndex: unsigned(AddressPoint - VTableIndex)}));
1758
1759 const ASTRecordLayout &Layout = Context.getASTRecordLayout(D: RD);
1760 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
1761
1762 if (!PrimaryBase)
1763 break;
1764
1765 if (Layout.isPrimaryBaseVirtual()) {
1766 // Check if this virtual primary base is a primary base in the layout
1767 // class. If it's not, we don't want to add it.
1768 const ASTRecordLayout &LayoutClassLayout =
1769 Context.getASTRecordLayout(D: LayoutClass);
1770
1771 if (LayoutClassLayout.getVBaseClassOffset(VBase: PrimaryBase) !=
1772 OffsetInLayoutClass) {
1773 // We don't want to add this class (or any of its primary bases).
1774 break;
1775 }
1776 }
1777
1778 RD = PrimaryBase;
1779 }
1780
1781 // Layout secondary vtables.
1782 LayoutSecondaryVTables(Base, BaseIsMorallyVirtual, OffsetInLayoutClass);
1783}
1784
1785void
1786ItaniumVTableBuilder::LayoutSecondaryVTables(BaseSubobject Base,
1787 bool BaseIsMorallyVirtual,
1788 CharUnits OffsetInLayoutClass) {
1789 // Itanium C++ ABI 2.5.2:
1790 // Following the primary virtual table of a derived class are secondary
1791 // virtual tables for each of its proper base classes, except any primary
1792 // base(s) with which it shares its primary virtual table.
1793
1794 const CXXRecordDecl *RD = Base.getBase();
1795 const ASTRecordLayout &Layout = Context.getASTRecordLayout(D: RD);
1796 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
1797
1798 for (const auto &B : RD->bases()) {
1799 // Ignore virtual bases, we'll emit them later.
1800 if (B.isVirtual())
1801 continue;
1802
1803 const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
1804
1805 // Ignore bases that don't have a vtable.
1806 if (!BaseDecl->isDynamicClass())
1807 continue;
1808
1809 if (isBuildingConstructorVTable()) {
1810 // Itanium C++ ABI 2.6.4:
1811 // Some of the base class subobjects may not need construction virtual
1812 // tables, which will therefore not be present in the construction
1813 // virtual table group, even though the subobject virtual tables are
1814 // present in the main virtual table group for the complete object.
1815 if (!BaseIsMorallyVirtual && !BaseDecl->getNumVBases())
1816 continue;
1817 }
1818
1819 // Get the base offset of this base.
1820 CharUnits RelativeBaseOffset = Layout.getBaseClassOffset(Base: BaseDecl);
1821 CharUnits BaseOffset = Base.getBaseOffset() + RelativeBaseOffset;
1822
1823 CharUnits BaseOffsetInLayoutClass =
1824 OffsetInLayoutClass + RelativeBaseOffset;
1825
1826 // Don't emit a secondary vtable for a primary base. We might however want
1827 // to emit secondary vtables for other bases of this base.
1828 if (BaseDecl == PrimaryBase) {
1829 LayoutSecondaryVTables(Base: BaseSubobject(BaseDecl, BaseOffset),
1830 BaseIsMorallyVirtual, OffsetInLayoutClass: BaseOffsetInLayoutClass);
1831 continue;
1832 }
1833
1834 // Layout the primary vtable (and any secondary vtables) for this base.
1835 LayoutPrimaryAndSecondaryVTables(
1836 Base: BaseSubobject(BaseDecl, BaseOffset),
1837 BaseIsMorallyVirtual,
1838 /*BaseIsVirtualInLayoutClass=*/false,
1839 OffsetInLayoutClass: BaseOffsetInLayoutClass);
1840 }
1841}
1842
1843void ItaniumVTableBuilder::DeterminePrimaryVirtualBases(
1844 const CXXRecordDecl *RD, CharUnits OffsetInLayoutClass,
1845 VisitedVirtualBasesSetTy &VBases) {
1846 const ASTRecordLayout &Layout = Context.getASTRecordLayout(D: RD);
1847
1848 // Check if this base has a primary base.
1849 if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
1850
1851 // Check if it's virtual.
1852 if (Layout.isPrimaryBaseVirtual()) {
1853 bool IsPrimaryVirtualBase = true;
1854
1855 if (isBuildingConstructorVTable()) {
1856 // Check if the base is actually a primary base in the class we use for
1857 // layout.
1858 const ASTRecordLayout &LayoutClassLayout =
1859 Context.getASTRecordLayout(D: LayoutClass);
1860
1861 CharUnits PrimaryBaseOffsetInLayoutClass =
1862 LayoutClassLayout.getVBaseClassOffset(VBase: PrimaryBase);
1863
1864 // We know that the base is not a primary base in the layout class if
1865 // the base offsets are different.
1866 if (PrimaryBaseOffsetInLayoutClass != OffsetInLayoutClass)
1867 IsPrimaryVirtualBase = false;
1868 }
1869
1870 if (IsPrimaryVirtualBase)
1871 PrimaryVirtualBases.insert(Ptr: PrimaryBase);
1872 }
1873 }
1874
1875 // Traverse bases, looking for more primary virtual bases.
1876 for (const auto &B : RD->bases()) {
1877 const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
1878
1879 CharUnits BaseOffsetInLayoutClass;
1880
1881 if (B.isVirtual()) {
1882 if (!VBases.insert(Ptr: BaseDecl).second)
1883 continue;
1884
1885 const ASTRecordLayout &LayoutClassLayout =
1886 Context.getASTRecordLayout(D: LayoutClass);
1887
1888 BaseOffsetInLayoutClass =
1889 LayoutClassLayout.getVBaseClassOffset(VBase: BaseDecl);
1890 } else {
1891 BaseOffsetInLayoutClass =
1892 OffsetInLayoutClass + Layout.getBaseClassOffset(Base: BaseDecl);
1893 }
1894
1895 DeterminePrimaryVirtualBases(RD: BaseDecl, OffsetInLayoutClass: BaseOffsetInLayoutClass, VBases);
1896 }
1897}
1898
1899void ItaniumVTableBuilder::LayoutVTablesForVirtualBases(
1900 const CXXRecordDecl *RD, VisitedVirtualBasesSetTy &VBases) {
1901 // Itanium C++ ABI 2.5.2:
1902 // Then come the virtual base virtual tables, also in inheritance graph
1903 // order, and again excluding primary bases (which share virtual tables with
1904 // the classes for which they are primary).
1905 for (const auto &B : RD->bases()) {
1906 const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
1907
1908 // Check if this base needs a vtable. (If it's virtual, not a primary base
1909 // of some other class, and we haven't visited it before).
1910 if (B.isVirtual() && BaseDecl->isDynamicClass() &&
1911 !PrimaryVirtualBases.count(Ptr: BaseDecl) &&
1912 VBases.insert(Ptr: BaseDecl).second) {
1913 const ASTRecordLayout &MostDerivedClassLayout =
1914 Context.getASTRecordLayout(D: MostDerivedClass);
1915 CharUnits BaseOffset =
1916 MostDerivedClassLayout.getVBaseClassOffset(VBase: BaseDecl);
1917
1918 const ASTRecordLayout &LayoutClassLayout =
1919 Context.getASTRecordLayout(D: LayoutClass);
1920 CharUnits BaseOffsetInLayoutClass =
1921 LayoutClassLayout.getVBaseClassOffset(VBase: BaseDecl);
1922
1923 LayoutPrimaryAndSecondaryVTables(
1924 Base: BaseSubobject(BaseDecl, BaseOffset),
1925 /*BaseIsMorallyVirtual=*/true,
1926 /*BaseIsVirtualInLayoutClass=*/true,
1927 OffsetInLayoutClass: BaseOffsetInLayoutClass);
1928 }
1929
1930 // We only need to check the base for virtual base vtables if it actually
1931 // has virtual bases.
1932 if (BaseDecl->getNumVBases())
1933 LayoutVTablesForVirtualBases(RD: BaseDecl, VBases);
1934 }
1935}
1936
1937static void printThunkMethod(const ThunkInfo &Info, raw_ostream &Out) {
1938 if (!Info.Method)
1939 return;
1940 std::string Str = PredefinedExpr::ComputeName(
1941 IK: PredefinedIdentKind::PrettyFunctionNoVirtual, CurrentDecl: Info.Method);
1942 Out << " method: " << Str;
1943}
1944
1945/// dumpLayout - Dump the vtable layout.
1946void ItaniumVTableBuilder::dumpLayout(raw_ostream &Out) {
1947 // FIXME: write more tests that actually use the dumpLayout output to prevent
1948 // ItaniumVTableBuilder regressions.
1949
1950 Out << "Original map\n";
1951
1952 for (const auto &P : VTables.getOriginalMethodMap()) {
1953 std::string Str0 =
1954 PredefinedExpr::ComputeName(IK: PredefinedIdentKind::PrettyFunctionNoVirtual,
1955 CurrentDecl: P.first);
1956 std::string Str1 =
1957 PredefinedExpr::ComputeName(IK: PredefinedIdentKind::PrettyFunctionNoVirtual,
1958 CurrentDecl: P.second);
1959 Out << " " << Str0 << " -> " << Str1 << "\n";
1960 }
1961
1962 if (isBuildingConstructorVTable()) {
1963 Out << "Construction vtable for ('";
1964 MostDerivedClass->printQualifiedName(OS&: Out);
1965 Out << "', ";
1966 Out << MostDerivedClassOffset.getQuantity() << ") in '";
1967 LayoutClass->printQualifiedName(OS&: Out);
1968 } else {
1969 Out << "Vtable for '";
1970 MostDerivedClass->printQualifiedName(OS&: Out);
1971 }
1972 Out << "' (" << Components.size() << " entries).\n";
1973
1974 // Iterate through the address points and insert them into a new map where
1975 // they are keyed by the index and not the base object.
1976 // Since an address point can be shared by multiple subobjects, we use an
1977 // STL multimap.
1978 std::multimap<uint64_t, BaseSubobject> AddressPointsByIndex;
1979 for (const auto &AP : AddressPoints) {
1980 const BaseSubobject &Base = AP.first;
1981 uint64_t Index =
1982 VTableIndices[AP.second.VTableIndex] + AP.second.AddressPointIndex;
1983
1984 AddressPointsByIndex.insert(x: std::make_pair(x&: Index, y: Base));
1985 }
1986
1987 for (unsigned I = 0, E = Components.size(); I != E; ++I) {
1988 uint64_t Index = I;
1989
1990 Out << llvm::format(Fmt: "%4d | ", Vals: I);
1991
1992 const VTableComponent &Component = Components[I];
1993
1994 // Dump the component.
1995 switch (Component.getKind()) {
1996
1997 case VTableComponent::CK_VCallOffset:
1998 Out << "vcall_offset ("
1999 << Component.getVCallOffset().getQuantity()
2000 << ")";
2001 break;
2002
2003 case VTableComponent::CK_VBaseOffset:
2004 Out << "vbase_offset ("
2005 << Component.getVBaseOffset().getQuantity()
2006 << ")";
2007 break;
2008
2009 case VTableComponent::CK_OffsetToTop:
2010 Out << "offset_to_top ("
2011 << Component.getOffsetToTop().getQuantity()
2012 << ")";
2013 break;
2014
2015 case VTableComponent::CK_RTTI:
2016 Component.getRTTIDecl()->printQualifiedName(OS&: Out);
2017 Out << " RTTI";
2018 break;
2019
2020 case VTableComponent::CK_FunctionPointer: {
2021 const CXXMethodDecl *MD = Component.getFunctionDecl();
2022
2023 std::string Str = PredefinedExpr::ComputeName(
2024 IK: PredefinedIdentKind::PrettyFunctionNoVirtual, CurrentDecl: MD);
2025 Out << Str;
2026 if (MD->isPureVirtual())
2027 Out << " [pure]";
2028
2029 if (MD->isDeleted())
2030 Out << " [deleted]";
2031
2032 ThunkInfo Thunk = VTableThunks.lookup(Val: I);
2033 if (!Thunk.isEmpty()) {
2034 // If this function pointer has a return adjustment, dump it.
2035 if (!Thunk.Return.isEmpty()) {
2036 Out << "\n [return adjustment: ";
2037 Out << Thunk.Return.NonVirtual << " non-virtual";
2038
2039 if (Thunk.Return.Virtual.Itanium.VBaseOffsetOffset) {
2040 Out << ", " << Thunk.Return.Virtual.Itanium.VBaseOffsetOffset;
2041 Out << " vbase offset offset";
2042 }
2043
2044 Out << ']';
2045 printThunkMethod(Info: Thunk, Out);
2046 }
2047
2048 // If this function pointer has a 'this' pointer adjustment, dump it.
2049 if (!Thunk.This.isEmpty()) {
2050 Out << "\n [this adjustment: ";
2051 Out << Thunk.This.NonVirtual << " non-virtual";
2052
2053 if (Thunk.This.Virtual.Itanium.VCallOffsetOffset) {
2054 Out << ", " << Thunk.This.Virtual.Itanium.VCallOffsetOffset;
2055 Out << " vcall offset offset";
2056 }
2057
2058 Out << ']';
2059 printThunkMethod(Info: Thunk, Out);
2060 }
2061 }
2062
2063 break;
2064 }
2065
2066 case VTableComponent::CK_CompleteDtorPointer:
2067 case VTableComponent::CK_DeletingDtorPointer: {
2068 bool IsComplete =
2069 Component.getKind() == VTableComponent::CK_CompleteDtorPointer;
2070
2071 const CXXDestructorDecl *DD = Component.getDestructorDecl();
2072
2073 DD->printQualifiedName(OS&: Out);
2074 if (IsComplete)
2075 Out << "() [complete]";
2076 else
2077 Out << "() [deleting]";
2078
2079 if (DD->isPureVirtual())
2080 Out << " [pure]";
2081
2082 ThunkInfo Thunk = VTableThunks.lookup(Val: I);
2083 if (!Thunk.isEmpty()) {
2084 // If this destructor has a 'this' pointer adjustment, dump it.
2085 if (!Thunk.This.isEmpty()) {
2086 Out << "\n [this adjustment: ";
2087 Out << Thunk.This.NonVirtual << " non-virtual";
2088
2089 if (Thunk.This.Virtual.Itanium.VCallOffsetOffset) {
2090 Out << ", " << Thunk.This.Virtual.Itanium.VCallOffsetOffset;
2091 Out << " vcall offset offset";
2092 }
2093
2094 Out << ']';
2095 }
2096 printThunkMethod(Info: Thunk, Out);
2097 }
2098
2099 break;
2100 }
2101
2102 case VTableComponent::CK_UnusedFunctionPointer: {
2103 const CXXMethodDecl *MD = Component.getUnusedFunctionDecl();
2104
2105 std::string Str = PredefinedExpr::ComputeName(
2106 IK: PredefinedIdentKind::PrettyFunctionNoVirtual, CurrentDecl: MD);
2107 Out << "[unused] " << Str;
2108 if (MD->isPureVirtual())
2109 Out << " [pure]";
2110 }
2111
2112 }
2113
2114 Out << '\n';
2115
2116 // Dump the next address point.
2117 uint64_t NextIndex = Index + 1;
2118 if (unsigned Count = AddressPointsByIndex.count(x: NextIndex)) {
2119 if (Count == 1) {
2120 const BaseSubobject &Base =
2121 AddressPointsByIndex.find(x: NextIndex)->second;
2122
2123 Out << " -- (";
2124 Base.getBase()->printQualifiedName(OS&: Out);
2125 Out << ", " << Base.getBaseOffset().getQuantity();
2126 Out << ") vtable address --\n";
2127 } else {
2128 CharUnits BaseOffset =
2129 AddressPointsByIndex.lower_bound(x: NextIndex)->second.getBaseOffset();
2130
2131 // We store the class names in a set to get a stable order.
2132 std::set<std::string> ClassNames;
2133 for (const auto &I :
2134 llvm::make_range(p: AddressPointsByIndex.equal_range(x: NextIndex))) {
2135 assert(I.second.getBaseOffset() == BaseOffset &&
2136 "Invalid base offset!");
2137 const CXXRecordDecl *RD = I.second.getBase();
2138 ClassNames.insert(x: RD->getQualifiedNameAsString());
2139 }
2140
2141 for (const std::string &Name : ClassNames) {
2142 Out << " -- (" << Name;
2143 Out << ", " << BaseOffset.getQuantity() << ") vtable address --\n";
2144 }
2145 }
2146 }
2147 }
2148
2149 Out << '\n';
2150
2151 if (isBuildingConstructorVTable())
2152 return;
2153
2154 if (MostDerivedClass->getNumVBases()) {
2155 // We store the virtual base class names and their offsets in a map to get
2156 // a stable order.
2157
2158 std::map<std::string, CharUnits> ClassNamesAndOffsets;
2159 for (const auto &I : VBaseOffsetOffsets) {
2160 std::string ClassName = I.first->getQualifiedNameAsString();
2161 CharUnits OffsetOffset = I.second;
2162 ClassNamesAndOffsets.insert(x: std::make_pair(x&: ClassName, y&: OffsetOffset));
2163 }
2164
2165 Out << "Virtual base offset offsets for '";
2166 MostDerivedClass->printQualifiedName(OS&: Out);
2167 Out << "' (";
2168 Out << ClassNamesAndOffsets.size();
2169 Out << (ClassNamesAndOffsets.size() == 1 ? " entry" : " entries") << ").\n";
2170
2171 for (const auto &I : ClassNamesAndOffsets)
2172 Out << " " << I.first << " | " << I.second.getQuantity() << '\n';
2173
2174 Out << "\n";
2175 }
2176
2177 if (!Thunks.empty()) {
2178 // We store the method names in a map to get a stable order.
2179 std::map<std::string, const CXXMethodDecl *> MethodNamesAndDecls;
2180
2181 for (const auto &I : Thunks) {
2182 const CXXMethodDecl *MD = I.first;
2183 std::string MethodName = PredefinedExpr::ComputeName(
2184 IK: PredefinedIdentKind::PrettyFunctionNoVirtual, CurrentDecl: MD);
2185
2186 MethodNamesAndDecls.insert(x: std::make_pair(x&: MethodName, y&: MD));
2187 }
2188
2189 for (const auto &I : MethodNamesAndDecls) {
2190 const std::string &MethodName = I.first;
2191 const CXXMethodDecl *MD = I.second;
2192
2193 ThunkInfoVectorTy ThunksVector = Thunks[MD];
2194 llvm::sort(C&: ThunksVector, Comp: [](const ThunkInfo &LHS, const ThunkInfo &RHS) {
2195 return std::tie(args: LHS.This, args: LHS.Return) < std::tie(args: RHS.This, args: RHS.Return);
2196 });
2197
2198 Out << "Thunks for '" << MethodName << "' (" << ThunksVector.size();
2199 Out << (ThunksVector.size() == 1 ? " entry" : " entries") << ").\n";
2200
2201 for (unsigned I = 0, E = ThunksVector.size(); I != E; ++I) {
2202 const ThunkInfo &Thunk = ThunksVector[I];
2203
2204 Out << llvm::format(Fmt: "%4d | ", Vals: I);
2205
2206 // If this function pointer has a return pointer adjustment, dump it.
2207 if (!Thunk.Return.isEmpty()) {
2208 Out << "return adjustment: " << Thunk.Return.NonVirtual;
2209 Out << " non-virtual";
2210 if (Thunk.Return.Virtual.Itanium.VBaseOffsetOffset) {
2211 Out << ", " << Thunk.Return.Virtual.Itanium.VBaseOffsetOffset;
2212 Out << " vbase offset offset";
2213 }
2214
2215 if (!Thunk.This.isEmpty())
2216 Out << "\n ";
2217 }
2218
2219 // If this function pointer has a 'this' pointer adjustment, dump it.
2220 if (!Thunk.This.isEmpty()) {
2221 Out << "this adjustment: ";
2222 Out << Thunk.This.NonVirtual << " non-virtual";
2223
2224 if (Thunk.This.Virtual.Itanium.VCallOffsetOffset) {
2225 Out << ", " << Thunk.This.Virtual.Itanium.VCallOffsetOffset;
2226 Out << " vcall offset offset";
2227 }
2228 }
2229
2230 Out << '\n';
2231 }
2232
2233 Out << '\n';
2234 }
2235 }
2236
2237 // Compute the vtable indices for all the member functions.
2238 // Store them in a map keyed by the index so we'll get a sorted table.
2239 std::map<uint64_t, std::string> IndicesMap;
2240
2241 for (const auto *MD : MostDerivedClass->methods()) {
2242 // We only want virtual member functions.
2243 if (!ItaniumVTableContext::hasVtableSlot(MD))
2244 continue;
2245 MD = MD->getCanonicalDecl();
2246
2247 std::string MethodName = PredefinedExpr::ComputeName(
2248 IK: PredefinedIdentKind::PrettyFunctionNoVirtual, CurrentDecl: MD);
2249
2250 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(Val: MD)) {
2251 GlobalDecl GD(DD, Dtor_Complete);
2252 assert(MethodVTableIndices.count(GD));
2253 uint64_t VTableIndex = MethodVTableIndices[GD];
2254 IndicesMap[VTableIndex] = MethodName + " [complete]";
2255 IndicesMap[VTableIndex + 1] = MethodName + " [deleting]";
2256 } else {
2257 assert(MethodVTableIndices.count(MD));
2258 IndicesMap[MethodVTableIndices[MD]] = MethodName;
2259 }
2260 }
2261
2262 // Print the vtable indices for all the member functions.
2263 if (!IndicesMap.empty()) {
2264 Out << "VTable indices for '";
2265 MostDerivedClass->printQualifiedName(OS&: Out);
2266 Out << "' (" << IndicesMap.size() << " entries).\n";
2267
2268 for (const auto &I : IndicesMap) {
2269 uint64_t VTableIndex = I.first;
2270 const std::string &MethodName = I.second;
2271
2272 Out << llvm::format(Fmt: "%4" PRIu64 " | ", Vals: VTableIndex) << MethodName
2273 << '\n';
2274 }
2275 }
2276
2277 Out << '\n';
2278}
2279}
2280
2281static VTableLayout::AddressPointsIndexMapTy
2282MakeAddressPointIndices(const VTableLayout::AddressPointsMapTy &addressPoints,
2283 unsigned numVTables) {
2284 VTableLayout::AddressPointsIndexMapTy indexMap(numVTables);
2285
2286 for (auto it = addressPoints.begin(); it != addressPoints.end(); ++it) {
2287 const auto &addressPointLoc = it->second;
2288 unsigned vtableIndex = addressPointLoc.VTableIndex;
2289 unsigned addressPoint = addressPointLoc.AddressPointIndex;
2290 if (indexMap[vtableIndex]) {
2291 // Multiple BaseSubobjects can map to the same AddressPointLocation, but
2292 // every vtable index should have a unique address point.
2293 assert(indexMap[vtableIndex] == addressPoint &&
2294 "Every vtable index should have a unique address point. Found a "
2295 "vtable that has two different address points.");
2296 } else {
2297 indexMap[vtableIndex] = addressPoint;
2298 }
2299 }
2300
2301 // Note that by this point, not all the address may be initialized if the
2302 // AddressPoints map is empty. This is ok if the map isn't needed. See
2303 // MicrosoftVTableContext::computeVTableRelatedInformation() which uses an
2304 // emprt map.
2305 return indexMap;
2306}
2307
2308VTableLayout::VTableLayout(ArrayRef<size_t> VTableIndices,
2309 ArrayRef<VTableComponent> VTableComponents,
2310 ArrayRef<VTableThunkTy> VTableThunks,
2311 const AddressPointsMapTy &AddressPoints)
2312 : VTableComponents(VTableComponents), VTableThunks(VTableThunks),
2313 AddressPoints(AddressPoints), AddressPointIndices(MakeAddressPointIndices(
2314 addressPoints: AddressPoints, numVTables: VTableIndices.size())) {
2315 if (VTableIndices.size() <= 1)
2316 assert(VTableIndices.size() == 1 && VTableIndices[0] == 0);
2317 else
2318 this->VTableIndices = OwningArrayRef<size_t>(VTableIndices);
2319
2320 llvm::sort(C&: this->VTableThunks, Comp: [](const VTableLayout::VTableThunkTy &LHS,
2321 const VTableLayout::VTableThunkTy &RHS) {
2322 assert((LHS.first != RHS.first || LHS.second == RHS.second) &&
2323 "Different thunks should have unique indices!");
2324 return LHS.first < RHS.first;
2325 });
2326}
2327
2328VTableLayout::~VTableLayout() { }
2329
2330bool VTableContextBase::hasVtableSlot(const CXXMethodDecl *MD) {
2331 return MD->isVirtual() && !MD->isImmediateFunction();
2332}
2333
2334ItaniumVTableContext::ItaniumVTableContext(
2335 ASTContext &Context, VTableComponentLayout ComponentLayout)
2336 : VTableContextBase(/*MS=*/false), ComponentLayout(ComponentLayout) {}
2337
2338ItaniumVTableContext::~ItaniumVTableContext() {}
2339
2340uint64_t ItaniumVTableContext::getMethodVTableIndex(GlobalDecl GD) {
2341 GD = GD.getCanonicalDecl();
2342 MethodVTableIndicesTy::iterator I = MethodVTableIndices.find(Val: GD);
2343 if (I != MethodVTableIndices.end())
2344 return I->second;
2345
2346 const CXXRecordDecl *RD = cast<CXXMethodDecl>(Val: GD.getDecl())->getParent();
2347
2348 computeVTableRelatedInformation(RD);
2349
2350 I = MethodVTableIndices.find(Val: GD);
2351 assert(I != MethodVTableIndices.end() && "Did not find index!");
2352 return I->second;
2353}
2354
2355CharUnits
2356ItaniumVTableContext::getVirtualBaseOffsetOffset(const CXXRecordDecl *RD,
2357 const CXXRecordDecl *VBase) {
2358 ClassPairTy ClassPair(RD, VBase);
2359
2360 VirtualBaseClassOffsetOffsetsMapTy::iterator I =
2361 VirtualBaseClassOffsetOffsets.find(Val: ClassPair);
2362 if (I != VirtualBaseClassOffsetOffsets.end())
2363 return I->second;
2364
2365 VCallAndVBaseOffsetBuilder Builder(*this, RD, RD, /*Overriders=*/nullptr,
2366 BaseSubobject(RD, CharUnits::Zero()),
2367 /*BaseIsVirtual=*/false,
2368 /*OffsetInLayoutClass=*/CharUnits::Zero());
2369
2370 for (const auto &I : Builder.getVBaseOffsetOffsets()) {
2371 // Insert all types.
2372 ClassPairTy ClassPair(RD, I.first);
2373
2374 VirtualBaseClassOffsetOffsets.insert(KV: std::make_pair(x&: ClassPair, y: I.second));
2375 }
2376
2377 I = VirtualBaseClassOffsetOffsets.find(Val: ClassPair);
2378 assert(I != VirtualBaseClassOffsetOffsets.end() && "Did not find index!");
2379
2380 return I->second;
2381}
2382
2383GlobalDecl ItaniumVTableContext::findOriginalMethod(GlobalDecl GD) {
2384 const auto *MD = cast<CXXMethodDecl>(Val: GD.getDecl());
2385 computeVTableRelatedInformation(RD: MD->getParent());
2386 const CXXMethodDecl *OriginalMD = findOriginalMethodInMap(MD);
2387
2388 if (const auto *DD = dyn_cast<CXXDestructorDecl>(Val: OriginalMD))
2389 return GlobalDecl(DD, GD.getDtorType());
2390 return OriginalMD;
2391}
2392
2393const CXXMethodDecl *
2394ItaniumVTableContext::findOriginalMethodInMap(const CXXMethodDecl *MD) const {
2395 // Traverse the chain of virtual methods until we find the method that added
2396 // the v-table slot.
2397 while (true) {
2398 auto I = OriginalMethodMap.find(Val: MD);
2399
2400 // MD doesn't exist in OriginalMethodMap, so it must be the method we are
2401 // looking for.
2402 if (I == OriginalMethodMap.end())
2403 break;
2404
2405 // Set MD to the overridden method.
2406 MD = I->second;
2407 }
2408
2409 return MD;
2410}
2411
2412static std::unique_ptr<VTableLayout>
2413CreateVTableLayout(const ItaniumVTableBuilder &Builder) {
2414 SmallVector<VTableLayout::VTableThunkTy, 1>
2415 VTableThunks(Builder.vtable_thunks_begin(), Builder.vtable_thunks_end());
2416
2417 return std::make_unique<VTableLayout>(
2418 args: Builder.VTableIndices, args: Builder.vtable_components(), args&: VTableThunks,
2419 args: Builder.getAddressPoints());
2420}
2421
2422void
2423ItaniumVTableContext::computeVTableRelatedInformation(const CXXRecordDecl *RD) {
2424 std::unique_ptr<const VTableLayout> &Entry = VTableLayouts[RD];
2425
2426 // Check if we've computed this information before.
2427 if (Entry)
2428 return;
2429
2430 ItaniumVTableBuilder Builder(*this, RD, CharUnits::Zero(),
2431 /*MostDerivedClassIsVirtual=*/false, RD);
2432 Entry = CreateVTableLayout(Builder);
2433
2434 MethodVTableIndices.insert(I: Builder.vtable_indices_begin(),
2435 E: Builder.vtable_indices_end());
2436
2437 // Add the known thunks.
2438 Thunks.insert(I: Builder.thunks_begin(), E: Builder.thunks_end());
2439
2440 // If we don't have the vbase information for this class, insert it.
2441 // getVirtualBaseOffsetOffset will compute it separately without computing
2442 // the rest of the vtable related information.
2443 if (!RD->getNumVBases())
2444 return;
2445
2446 const CXXRecordDecl *VBase =
2447 RD->vbases_begin()->getType()->getAsCXXRecordDecl();
2448
2449 if (VirtualBaseClassOffsetOffsets.count(Val: std::make_pair(x&: RD, y&: VBase)))
2450 return;
2451
2452 for (const auto &I : Builder.getVBaseOffsetOffsets()) {
2453 // Insert all types.
2454 ClassPairTy ClassPair(RD, I.first);
2455
2456 VirtualBaseClassOffsetOffsets.insert(KV: std::make_pair(x&: ClassPair, y: I.second));
2457 }
2458}
2459
2460std::unique_ptr<VTableLayout>
2461ItaniumVTableContext::createConstructionVTableLayout(
2462 const CXXRecordDecl *MostDerivedClass, CharUnits MostDerivedClassOffset,
2463 bool MostDerivedClassIsVirtual, const CXXRecordDecl *LayoutClass) {
2464 ItaniumVTableBuilder Builder(*this, MostDerivedClass, MostDerivedClassOffset,
2465 MostDerivedClassIsVirtual, LayoutClass);
2466 return CreateVTableLayout(Builder);
2467}
2468
2469namespace {
2470
2471// Vtables in the Microsoft ABI are different from the Itanium ABI.
2472//
2473// The main differences are:
2474// 1. Separate vftable and vbtable.
2475//
2476// 2. Each subobject with a vfptr gets its own vftable rather than an address
2477// point in a single vtable shared between all the subobjects.
2478// Each vftable is represented by a separate section and virtual calls
2479// must be done using the vftable which has a slot for the function to be
2480// called.
2481//
2482// 3. Virtual method definitions expect their 'this' parameter to point to the
2483// first vfptr whose table provides a compatible overridden method. In many
2484// cases, this permits the original vf-table entry to directly call
2485// the method instead of passing through a thunk.
2486// See example before VFTableBuilder::ComputeThisOffset below.
2487//
2488// A compatible overridden method is one which does not have a non-trivial
2489// covariant-return adjustment.
2490//
2491// The first vfptr is the one with the lowest offset in the complete-object
2492// layout of the defining class, and the method definition will subtract
2493// that constant offset from the parameter value to get the real 'this'
2494// value. Therefore, if the offset isn't really constant (e.g. if a virtual
2495// function defined in a virtual base is overridden in a more derived
2496// virtual base and these bases have a reverse order in the complete
2497// object), the vf-table may require a this-adjustment thunk.
2498//
2499// 4. vftables do not contain new entries for overrides that merely require
2500// this-adjustment. Together with #3, this keeps vf-tables smaller and
2501// eliminates the need for this-adjustment thunks in many cases, at the cost
2502// of often requiring redundant work to adjust the "this" pointer.
2503//
2504// 5. Instead of VTT and constructor vtables, vbtables and vtordisps are used.
2505// Vtordisps are emitted into the class layout if a class has
2506// a) a user-defined ctor/dtor
2507// and
2508// b) a method overriding a method in a virtual base.
2509//
2510// To get a better understanding of this code,
2511// you might want to see examples in test/CodeGenCXX/microsoft-abi-vtables-*.cpp
2512
2513class VFTableBuilder {
2514public:
2515 typedef llvm::DenseMap<GlobalDecl, MethodVFTableLocation>
2516 MethodVFTableLocationsTy;
2517
2518 typedef llvm::iterator_range<MethodVFTableLocationsTy::const_iterator>
2519 method_locations_range;
2520
2521private:
2522 /// VTables - Global vtable information.
2523 MicrosoftVTableContext &VTables;
2524
2525 /// Context - The ASTContext which we will use for layout information.
2526 ASTContext &Context;
2527
2528 /// MostDerivedClass - The most derived class for which we're building this
2529 /// vtable.
2530 const CXXRecordDecl *MostDerivedClass;
2531
2532 const ASTRecordLayout &MostDerivedClassLayout;
2533
2534 const VPtrInfo &WhichVFPtr;
2535
2536 /// FinalOverriders - The final overriders of the most derived class.
2537 const FinalOverriders Overriders;
2538
2539 /// Components - The components of the vftable being built.
2540 SmallVector<VTableComponent, 64> Components;
2541
2542 MethodVFTableLocationsTy MethodVFTableLocations;
2543
2544 /// Does this class have an RTTI component?
2545 bool HasRTTIComponent = false;
2546
2547 /// MethodInfo - Contains information about a method in a vtable.
2548 /// (Used for computing 'this' pointer adjustment thunks.
2549 struct MethodInfo {
2550 /// VBTableIndex - The nonzero index in the vbtable that
2551 /// this method's base has, or zero.
2552 const uint64_t VBTableIndex;
2553
2554 /// VFTableIndex - The index in the vftable that this method has.
2555 const uint64_t VFTableIndex;
2556
2557 /// Shadowed - Indicates if this vftable slot is shadowed by
2558 /// a slot for a covariant-return override. If so, it shouldn't be printed
2559 /// or used for vcalls in the most derived class.
2560 bool Shadowed;
2561
2562 /// UsesExtraSlot - Indicates if this vftable slot was created because
2563 /// any of the overridden slots required a return adjusting thunk.
2564 bool UsesExtraSlot;
2565
2566 MethodInfo(uint64_t VBTableIndex, uint64_t VFTableIndex,
2567 bool UsesExtraSlot = false)
2568 : VBTableIndex(VBTableIndex), VFTableIndex(VFTableIndex),
2569 Shadowed(false), UsesExtraSlot(UsesExtraSlot) {}
2570
2571 MethodInfo()
2572 : VBTableIndex(0), VFTableIndex(0), Shadowed(false),
2573 UsesExtraSlot(false) {}
2574 };
2575
2576 typedef llvm::DenseMap<const CXXMethodDecl *, MethodInfo> MethodInfoMapTy;
2577
2578 /// MethodInfoMap - The information for all methods in the vftable we're
2579 /// currently building.
2580 MethodInfoMapTy MethodInfoMap;
2581
2582 typedef llvm::DenseMap<uint64_t, ThunkInfo> VTableThunksMapTy;
2583
2584 /// VTableThunks - The thunks by vftable index in the vftable currently being
2585 /// built.
2586 VTableThunksMapTy VTableThunks;
2587
2588 typedef SmallVector<ThunkInfo, 1> ThunkInfoVectorTy;
2589 typedef llvm::DenseMap<const CXXMethodDecl *, ThunkInfoVectorTy> ThunksMapTy;
2590
2591 /// Thunks - A map that contains all the thunks needed for all methods in the
2592 /// most derived class for which the vftable is currently being built.
2593 ThunksMapTy Thunks;
2594
2595 /// AddThunk - Add a thunk for the given method.
2596 void AddThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk) {
2597 SmallVector<ThunkInfo, 1> &ThunksVector = Thunks[MD];
2598
2599 // Check if we have this thunk already.
2600 if (llvm::is_contained(Range&: ThunksVector, Element: Thunk))
2601 return;
2602
2603 ThunksVector.push_back(Elt: Thunk);
2604 }
2605
2606 /// ComputeThisOffset - Returns the 'this' argument offset for the given
2607 /// method, relative to the beginning of the MostDerivedClass.
2608 CharUnits ComputeThisOffset(FinalOverriders::OverriderInfo Overrider);
2609
2610 void CalculateVtordispAdjustment(FinalOverriders::OverriderInfo Overrider,
2611 CharUnits ThisOffset, ThisAdjustment &TA);
2612
2613 /// AddMethod - Add a single virtual member function to the vftable
2614 /// components vector.
2615 void AddMethod(const CXXMethodDecl *MD, ThunkInfo TI) {
2616 if (!TI.isEmpty()) {
2617 VTableThunks[Components.size()] = TI;
2618 AddThunk(MD, Thunk: TI);
2619 }
2620 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(Val: MD)) {
2621 assert(TI.Return.isEmpty() &&
2622 "Destructor can't have return adjustment!");
2623 Components.push_back(Elt: VTableComponent::MakeDeletingDtor(DD));
2624 } else {
2625 Components.push_back(Elt: VTableComponent::MakeFunction(MD));
2626 }
2627 }
2628
2629 /// AddMethods - Add the methods of this base subobject and the relevant
2630 /// subbases to the vftable we're currently laying out.
2631 void AddMethods(BaseSubobject Base, unsigned BaseDepth,
2632 const CXXRecordDecl *LastVBase,
2633 BasesSetVectorTy &VisitedBases);
2634
2635 void LayoutVFTable() {
2636 // RTTI data goes before all other entries.
2637 if (HasRTTIComponent)
2638 Components.push_back(Elt: VTableComponent::MakeRTTI(RD: MostDerivedClass));
2639
2640 BasesSetVectorTy VisitedBases;
2641 AddMethods(Base: BaseSubobject(MostDerivedClass, CharUnits::Zero()), BaseDepth: 0, LastVBase: nullptr,
2642 VisitedBases);
2643 // Note that it is possible for the vftable to contain only an RTTI
2644 // pointer, if all virtual functions are constewval.
2645 assert(!Components.empty() && "vftable can't be empty");
2646
2647 assert(MethodVFTableLocations.empty());
2648 for (const auto &I : MethodInfoMap) {
2649 const CXXMethodDecl *MD = I.first;
2650 const MethodInfo &MI = I.second;
2651 assert(MD == MD->getCanonicalDecl());
2652
2653 // Skip the methods that the MostDerivedClass didn't override
2654 // and the entries shadowed by return adjusting thunks.
2655 if (MD->getParent() != MostDerivedClass || MI.Shadowed)
2656 continue;
2657 MethodVFTableLocation Loc(MI.VBTableIndex, WhichVFPtr.getVBaseWithVPtr(),
2658 WhichVFPtr.NonVirtualOffset, MI.VFTableIndex);
2659 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(Val: MD)) {
2660 MethodVFTableLocations[GlobalDecl(DD, Dtor_Deleting)] = Loc;
2661 } else {
2662 MethodVFTableLocations[MD] = Loc;
2663 }
2664 }
2665 }
2666
2667public:
2668 VFTableBuilder(MicrosoftVTableContext &VTables,
2669 const CXXRecordDecl *MostDerivedClass, const VPtrInfo &Which)
2670 : VTables(VTables),
2671 Context(MostDerivedClass->getASTContext()),
2672 MostDerivedClass(MostDerivedClass),
2673 MostDerivedClassLayout(Context.getASTRecordLayout(D: MostDerivedClass)),
2674 WhichVFPtr(Which),
2675 Overriders(MostDerivedClass, CharUnits(), MostDerivedClass) {
2676 // Provide the RTTI component if RTTIData is enabled. If the vftable would
2677 // be available externally, we should not provide the RTTI componenent. It
2678 // is currently impossible to get available externally vftables with either
2679 // dllimport or extern template instantiations, but eventually we may add a
2680 // flag to support additional devirtualization that needs this.
2681 if (Context.getLangOpts().RTTIData)
2682 HasRTTIComponent = true;
2683
2684 LayoutVFTable();
2685
2686 if (Context.getLangOpts().DumpVTableLayouts)
2687 dumpLayout(llvm::outs());
2688 }
2689
2690 uint64_t getNumThunks() const { return Thunks.size(); }
2691
2692 ThunksMapTy::const_iterator thunks_begin() const { return Thunks.begin(); }
2693
2694 ThunksMapTy::const_iterator thunks_end() const { return Thunks.end(); }
2695
2696 method_locations_range vtable_locations() const {
2697 return method_locations_range(MethodVFTableLocations.begin(),
2698 MethodVFTableLocations.end());
2699 }
2700
2701 ArrayRef<VTableComponent> vtable_components() const { return Components; }
2702
2703 VTableThunksMapTy::const_iterator vtable_thunks_begin() const {
2704 return VTableThunks.begin();
2705 }
2706
2707 VTableThunksMapTy::const_iterator vtable_thunks_end() const {
2708 return VTableThunks.end();
2709 }
2710
2711 void dumpLayout(raw_ostream &);
2712};
2713
2714} // end namespace
2715
2716// Let's study one class hierarchy as an example:
2717// struct A {
2718// virtual void f();
2719// int x;
2720// };
2721//
2722// struct B : virtual A {
2723// virtual void f();
2724// };
2725//
2726// Record layouts:
2727// struct A:
2728// 0 | (A vftable pointer)
2729// 4 | int x
2730//
2731// struct B:
2732// 0 | (B vbtable pointer)
2733// 4 | struct A (virtual base)
2734// 4 | (A vftable pointer)
2735// 8 | int x
2736//
2737// Let's assume we have a pointer to the A part of an object of dynamic type B:
2738// B b;
2739// A *a = (A*)&b;
2740// a->f();
2741//
2742// In this hierarchy, f() belongs to the vftable of A, so B::f() expects
2743// "this" parameter to point at the A subobject, which is B+4.
2744// In the B::f() prologue, it adjusts "this" back to B by subtracting 4,
2745// performed as a *static* adjustment.
2746//
2747// Interesting thing happens when we alter the relative placement of A and B
2748// subobjects in a class:
2749// struct C : virtual B { };
2750//
2751// C c;
2752// A *a = (A*)&c;
2753// a->f();
2754//
2755// Respective record layout is:
2756// 0 | (C vbtable pointer)
2757// 4 | struct A (virtual base)
2758// 4 | (A vftable pointer)
2759// 8 | int x
2760// 12 | struct B (virtual base)
2761// 12 | (B vbtable pointer)
2762//
2763// The final overrider of f() in class C is still B::f(), so B+4 should be
2764// passed as "this" to that code. However, "a" points at B-8, so the respective
2765// vftable entry should hold a thunk that adds 12 to the "this" argument before
2766// performing a tail call to B::f().
2767//
2768// With this example in mind, we can now calculate the 'this' argument offset
2769// for the given method, relative to the beginning of the MostDerivedClass.
2770CharUnits
2771VFTableBuilder::ComputeThisOffset(FinalOverriders::OverriderInfo Overrider) {
2772 BasesSetVectorTy Bases;
2773
2774 {
2775 // Find the set of least derived bases that define the given method.
2776 OverriddenMethodsSetTy VisitedOverriddenMethods;
2777 auto InitialOverriddenDefinitionCollector = [&](
2778 const CXXMethodDecl *OverriddenMD) {
2779 if (OverriddenMD->size_overridden_methods() == 0)
2780 Bases.insert(X: OverriddenMD->getParent());
2781 // Don't recurse on this method if we've already collected it.
2782 return VisitedOverriddenMethods.insert(Ptr: OverriddenMD).second;
2783 };
2784 visitAllOverriddenMethods(MD: Overrider.Method,
2785 Visitor&: InitialOverriddenDefinitionCollector);
2786 }
2787
2788 // If there are no overrides then 'this' is located
2789 // in the base that defines the method.
2790 if (Bases.size() == 0)
2791 return Overrider.Offset;
2792
2793 CXXBasePaths Paths;
2794 Overrider.Method->getParent()->lookupInBases(
2795 BaseMatches: [&Bases](const CXXBaseSpecifier *Specifier, CXXBasePath &) {
2796 return Bases.count(key: Specifier->getType()->getAsCXXRecordDecl());
2797 },
2798 Paths);
2799
2800 // This will hold the smallest this offset among overridees of MD.
2801 // This implies that an offset of a non-virtual base will dominate an offset
2802 // of a virtual base to potentially reduce the number of thunks required
2803 // in the derived classes that inherit this method.
2804 CharUnits Ret;
2805 bool First = true;
2806
2807 const ASTRecordLayout &OverriderRDLayout =
2808 Context.getASTRecordLayout(D: Overrider.Method->getParent());
2809 for (const CXXBasePath &Path : Paths) {
2810 CharUnits ThisOffset = Overrider.Offset;
2811 CharUnits LastVBaseOffset;
2812
2813 // For each path from the overrider to the parents of the overridden
2814 // methods, traverse the path, calculating the this offset in the most
2815 // derived class.
2816 for (const CXXBasePathElement &Element : Path) {
2817 QualType CurTy = Element.Base->getType();
2818 const CXXRecordDecl *PrevRD = Element.Class,
2819 *CurRD = CurTy->getAsCXXRecordDecl();
2820 const ASTRecordLayout &Layout = Context.getASTRecordLayout(D: PrevRD);
2821
2822 if (Element.Base->isVirtual()) {
2823 // The interesting things begin when you have virtual inheritance.
2824 // The final overrider will use a static adjustment equal to the offset
2825 // of the vbase in the final overrider class.
2826 // For example, if the final overrider is in a vbase B of the most
2827 // derived class and it overrides a method of the B's own vbase A,
2828 // it uses A* as "this". In its prologue, it can cast A* to B* with
2829 // a static offset. This offset is used regardless of the actual
2830 // offset of A from B in the most derived class, requiring an
2831 // this-adjusting thunk in the vftable if A and B are laid out
2832 // differently in the most derived class.
2833 LastVBaseOffset = ThisOffset =
2834 Overrider.Offset + OverriderRDLayout.getVBaseClassOffset(VBase: CurRD);
2835 } else {
2836 ThisOffset += Layout.getBaseClassOffset(Base: CurRD);
2837 }
2838 }
2839
2840 if (isa<CXXDestructorDecl>(Val: Overrider.Method)) {
2841 if (LastVBaseOffset.isZero()) {
2842 // If a "Base" class has at least one non-virtual base with a virtual
2843 // destructor, the "Base" virtual destructor will take the address
2844 // of the "Base" subobject as the "this" argument.
2845 ThisOffset = Overrider.Offset;
2846 } else {
2847 // A virtual destructor of a virtual base takes the address of the
2848 // virtual base subobject as the "this" argument.
2849 ThisOffset = LastVBaseOffset;
2850 }
2851 }
2852
2853 if (Ret > ThisOffset || First) {
2854 First = false;
2855 Ret = ThisOffset;
2856 }
2857 }
2858
2859 assert(!First && "Method not found in the given subobject?");
2860 return Ret;
2861}
2862
2863// Things are getting even more complex when the "this" adjustment has to
2864// use a dynamic offset instead of a static one, or even two dynamic offsets.
2865// This is sometimes required when a virtual call happens in the middle of
2866// a non-most-derived class construction or destruction.
2867//
2868// Let's take a look at the following example:
2869// struct A {
2870// virtual void f();
2871// };
2872//
2873// void foo(A *a) { a->f(); } // Knows nothing about siblings of A.
2874//
2875// struct B : virtual A {
2876// virtual void f();
2877// B() {
2878// foo(this);
2879// }
2880// };
2881//
2882// struct C : virtual B {
2883// virtual void f();
2884// };
2885//
2886// Record layouts for these classes are:
2887// struct A
2888// 0 | (A vftable pointer)
2889//
2890// struct B
2891// 0 | (B vbtable pointer)
2892// 4 | (vtordisp for vbase A)
2893// 8 | struct A (virtual base)
2894// 8 | (A vftable pointer)
2895//
2896// struct C
2897// 0 | (C vbtable pointer)
2898// 4 | (vtordisp for vbase A)
2899// 8 | struct A (virtual base) // A precedes B!
2900// 8 | (A vftable pointer)
2901// 12 | struct B (virtual base)
2902// 12 | (B vbtable pointer)
2903//
2904// When one creates an object of type C, the C constructor:
2905// - initializes all the vbptrs, then
2906// - calls the A subobject constructor
2907// (initializes A's vfptr with an address of A vftable), then
2908// - calls the B subobject constructor
2909// (initializes A's vfptr with an address of B vftable and vtordisp for A),
2910// that in turn calls foo(), then
2911// - initializes A's vfptr with an address of C vftable and zeroes out the
2912// vtordisp
2913// FIXME: if a structor knows it belongs to MDC, why doesn't it use a vftable
2914// without vtordisp thunks?
2915// FIXME: how are vtordisp handled in the presence of nooverride/final?
2916//
2917// When foo() is called, an object with a layout of class C has a vftable
2918// referencing B::f() that assumes a B layout, so the "this" adjustments are
2919// incorrect, unless an extra adjustment is done. This adjustment is called
2920// "vtordisp adjustment". Vtordisp basically holds the difference between the
2921// actual location of a vbase in the layout class and the location assumed by
2922// the vftable of the class being constructed/destructed. Vtordisp is only
2923// needed if "this" escapes a
2924// structor (or we can't prove otherwise).
2925// [i.e. vtordisp is a dynamic adjustment for a static adjustment, which is an
2926// estimation of a dynamic adjustment]
2927//
2928// foo() gets a pointer to the A vbase and doesn't know anything about B or C,
2929// so it just passes that pointer as "this" in a virtual call.
2930// If there was no vtordisp, that would just dispatch to B::f().
2931// However, B::f() assumes B+8 is passed as "this",
2932// yet the pointer foo() passes along is B-4 (i.e. C+8).
2933// An extra adjustment is needed, so we emit a thunk into the B vftable.
2934// This vtordisp thunk subtracts the value of vtordisp
2935// from the "this" argument (-12) before making a tailcall to B::f().
2936//
2937// Let's consider an even more complex example:
2938// struct D : virtual B, virtual C {
2939// D() {
2940// foo(this);
2941// }
2942// };
2943//
2944// struct D
2945// 0 | (D vbtable pointer)
2946// 4 | (vtordisp for vbase A)
2947// 8 | struct A (virtual base) // A precedes both B and C!
2948// 8 | (A vftable pointer)
2949// 12 | struct B (virtual base) // B precedes C!
2950// 12 | (B vbtable pointer)
2951// 16 | struct C (virtual base)
2952// 16 | (C vbtable pointer)
2953//
2954// When D::D() calls foo(), we find ourselves in a thunk that should tailcall
2955// to C::f(), which assumes C+8 as its "this" parameter. This time, foo()
2956// passes along A, which is C-8. The A vtordisp holds
2957// "D.vbptr[index_of_A] - offset_of_A_in_D"
2958// and we statically know offset_of_A_in_D, so can get a pointer to D.
2959// When we know it, we can make an extra vbtable lookup to locate the C vbase
2960// and one extra static adjustment to calculate the expected value of C+8.
2961void VFTableBuilder::CalculateVtordispAdjustment(
2962 FinalOverriders::OverriderInfo Overrider, CharUnits ThisOffset,
2963 ThisAdjustment &TA) {
2964 const ASTRecordLayout::VBaseOffsetsMapTy &VBaseMap =
2965 MostDerivedClassLayout.getVBaseOffsetsMap();
2966 const ASTRecordLayout::VBaseOffsetsMapTy::const_iterator &VBaseMapEntry =
2967 VBaseMap.find(Val: WhichVFPtr.getVBaseWithVPtr());
2968 assert(VBaseMapEntry != VBaseMap.end());
2969
2970 // If there's no vtordisp or the final overrider is defined in the same vbase
2971 // as the initial declaration, we don't need any vtordisp adjustment.
2972 if (!VBaseMapEntry->second.hasVtorDisp() ||
2973 Overrider.VirtualBase == WhichVFPtr.getVBaseWithVPtr())
2974 return;
2975
2976 // OK, now we know we need to use a vtordisp thunk.
2977 // The implicit vtordisp field is located right before the vbase.
2978 CharUnits OffsetOfVBaseWithVFPtr = VBaseMapEntry->second.VBaseOffset;
2979 TA.Virtual.Microsoft.VtordispOffset =
2980 (OffsetOfVBaseWithVFPtr - WhichVFPtr.FullOffsetInMDC).getQuantity() - 4;
2981
2982 // A simple vtordisp thunk will suffice if the final overrider is defined
2983 // in either the most derived class or its non-virtual base.
2984 if (Overrider.Method->getParent() == MostDerivedClass ||
2985 !Overrider.VirtualBase)
2986 return;
2987
2988 // Otherwise, we need to do use the dynamic offset of the final overrider
2989 // in order to get "this" adjustment right.
2990 TA.Virtual.Microsoft.VBPtrOffset =
2991 (OffsetOfVBaseWithVFPtr + WhichVFPtr.NonVirtualOffset -
2992 MostDerivedClassLayout.getVBPtrOffset()).getQuantity();
2993 TA.Virtual.Microsoft.VBOffsetOffset =
2994 Context.getTypeSizeInChars(T: Context.IntTy).getQuantity() *
2995 VTables.getVBTableIndex(Derived: MostDerivedClass, VBase: Overrider.VirtualBase);
2996
2997 TA.NonVirtual = (ThisOffset - Overrider.Offset).getQuantity();
2998}
2999
3000static void GroupNewVirtualOverloads(
3001 const CXXRecordDecl *RD,
3002 SmallVector<const CXXMethodDecl *, 10> &VirtualMethods) {
3003 // Put the virtual methods into VirtualMethods in the proper order:
3004 // 1) Group overloads by declaration name. New groups are added to the
3005 // vftable in the order of their first declarations in this class
3006 // (including overrides, non-virtual methods and any other named decl that
3007 // might be nested within the class).
3008 // 2) In each group, new overloads appear in the reverse order of declaration.
3009 typedef SmallVector<const CXXMethodDecl *, 1> MethodGroup;
3010 SmallVector<MethodGroup, 10> Groups;
3011 typedef llvm::DenseMap<DeclarationName, unsigned> VisitedGroupIndicesTy;
3012 VisitedGroupIndicesTy VisitedGroupIndices;
3013 for (const auto *D : RD->decls()) {
3014 const auto *ND = dyn_cast<NamedDecl>(Val: D);
3015 if (!ND)
3016 continue;
3017 VisitedGroupIndicesTy::iterator J;
3018 bool Inserted;
3019 std::tie(args&: J, args&: Inserted) = VisitedGroupIndices.insert(
3020 KV: std::make_pair(x: ND->getDeclName(), y: Groups.size()));
3021 if (Inserted)
3022 Groups.push_back(Elt: MethodGroup());
3023 if (const auto *MD = dyn_cast<CXXMethodDecl>(Val: ND))
3024 if (MicrosoftVTableContext::hasVtableSlot(MD))
3025 Groups[J->second].push_back(Elt: MD->getCanonicalDecl());
3026 }
3027
3028 for (const MethodGroup &Group : Groups)
3029 VirtualMethods.append(in_start: Group.rbegin(), in_end: Group.rend());
3030}
3031
3032static bool isDirectVBase(const CXXRecordDecl *Base, const CXXRecordDecl *RD) {
3033 for (const auto &B : RD->bases()) {
3034 if (B.isVirtual() && B.getType()->getAsCXXRecordDecl() == Base)
3035 return true;
3036 }
3037 return false;
3038}
3039
3040void VFTableBuilder::AddMethods(BaseSubobject Base, unsigned BaseDepth,
3041 const CXXRecordDecl *LastVBase,
3042 BasesSetVectorTy &VisitedBases) {
3043 const CXXRecordDecl *RD = Base.getBase();
3044 if (!RD->isPolymorphic())
3045 return;
3046
3047 const ASTRecordLayout &Layout = Context.getASTRecordLayout(D: RD);
3048
3049 // See if this class expands a vftable of the base we look at, which is either
3050 // the one defined by the vfptr base path or the primary base of the current
3051 // class.
3052 const CXXRecordDecl *NextBase = nullptr, *NextLastVBase = LastVBase;
3053 CharUnits NextBaseOffset;
3054 if (BaseDepth < WhichVFPtr.PathToIntroducingObject.size()) {
3055 NextBase = WhichVFPtr.PathToIntroducingObject[BaseDepth];
3056 if (isDirectVBase(Base: NextBase, RD)) {
3057 NextLastVBase = NextBase;
3058 NextBaseOffset = MostDerivedClassLayout.getVBaseClassOffset(VBase: NextBase);
3059 } else {
3060 NextBaseOffset =
3061 Base.getBaseOffset() + Layout.getBaseClassOffset(Base: NextBase);
3062 }
3063 } else if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
3064 assert(!Layout.isPrimaryBaseVirtual() &&
3065 "No primary virtual bases in this ABI");
3066 NextBase = PrimaryBase;
3067 NextBaseOffset = Base.getBaseOffset();
3068 }
3069
3070 if (NextBase) {
3071 AddMethods(Base: BaseSubobject(NextBase, NextBaseOffset), BaseDepth: BaseDepth + 1,
3072 LastVBase: NextLastVBase, VisitedBases);
3073 if (!VisitedBases.insert(X: NextBase))
3074 llvm_unreachable("Found a duplicate primary base!");
3075 }
3076
3077 SmallVector<const CXXMethodDecl*, 10> VirtualMethods;
3078 // Put virtual methods in the proper order.
3079 GroupNewVirtualOverloads(RD, VirtualMethods);
3080
3081 // Now go through all virtual member functions and add them to the current
3082 // vftable. This is done by
3083 // - replacing overridden methods in their existing slots, as long as they
3084 // don't require return adjustment; calculating This adjustment if needed.
3085 // - adding new slots for methods of the current base not present in any
3086 // sub-bases;
3087 // - adding new slots for methods that require Return adjustment.
3088 // We keep track of the methods visited in the sub-bases in MethodInfoMap.
3089 for (const CXXMethodDecl *MD : VirtualMethods) {
3090 FinalOverriders::OverriderInfo FinalOverrider =
3091 Overriders.getOverrider(MD, BaseOffset: Base.getBaseOffset());
3092 const CXXMethodDecl *FinalOverriderMD = FinalOverrider.Method;
3093 const CXXMethodDecl *OverriddenMD =
3094 FindNearestOverriddenMethod(MD, Bases&: VisitedBases);
3095
3096 ThisAdjustment ThisAdjustmentOffset;
3097 bool ReturnAdjustingThunk = false, ForceReturnAdjustmentMangling = false;
3098 CharUnits ThisOffset = ComputeThisOffset(Overrider: FinalOverrider);
3099 ThisAdjustmentOffset.NonVirtual =
3100 (ThisOffset - WhichVFPtr.FullOffsetInMDC).getQuantity();
3101 if ((OverriddenMD || FinalOverriderMD != MD) &&
3102 WhichVFPtr.getVBaseWithVPtr())
3103 CalculateVtordispAdjustment(Overrider: FinalOverrider, ThisOffset,
3104 TA&: ThisAdjustmentOffset);
3105
3106 unsigned VBIndex =
3107 LastVBase ? VTables.getVBTableIndex(Derived: MostDerivedClass, VBase: LastVBase) : 0;
3108
3109 if (OverriddenMD) {
3110 // If MD overrides anything in this vftable, we need to update the
3111 // entries.
3112 MethodInfoMapTy::iterator OverriddenMDIterator =
3113 MethodInfoMap.find(Val: OverriddenMD);
3114
3115 // If the overridden method went to a different vftable, skip it.
3116 if (OverriddenMDIterator == MethodInfoMap.end())
3117 continue;
3118
3119 MethodInfo &OverriddenMethodInfo = OverriddenMDIterator->second;
3120
3121 VBIndex = OverriddenMethodInfo.VBTableIndex;
3122
3123 // Let's check if the overrider requires any return adjustments.
3124 // We must create a new slot if the MD's return type is not trivially
3125 // convertible to the OverriddenMD's one.
3126 // Once a chain of method overrides adds a return adjusting vftable slot,
3127 // all subsequent overrides will also use an extra method slot.
3128 ReturnAdjustingThunk = !ComputeReturnAdjustmentBaseOffset(
3129 Context, DerivedMD: MD, BaseMD: OverriddenMD).isEmpty() ||
3130 OverriddenMethodInfo.UsesExtraSlot;
3131
3132 if (!ReturnAdjustingThunk) {
3133 // No return adjustment needed - just replace the overridden method info
3134 // with the current info.
3135 MethodInfo MI(VBIndex, OverriddenMethodInfo.VFTableIndex);
3136 MethodInfoMap.erase(I: OverriddenMDIterator);
3137
3138 assert(!MethodInfoMap.count(MD) &&
3139 "Should not have method info for this method yet!");
3140 MethodInfoMap.insert(KV: std::make_pair(x&: MD, y&: MI));
3141 continue;
3142 }
3143
3144 // In case we need a return adjustment, we'll add a new slot for
3145 // the overrider. Mark the overridden method as shadowed by the new slot.
3146 OverriddenMethodInfo.Shadowed = true;
3147
3148 // Force a special name mangling for a return-adjusting thunk
3149 // unless the method is the final overrider without this adjustment.
3150 ForceReturnAdjustmentMangling =
3151 !(MD == FinalOverriderMD && ThisAdjustmentOffset.isEmpty());
3152 } else if (Base.getBaseOffset() != WhichVFPtr.FullOffsetInMDC ||
3153 MD->size_overridden_methods()) {
3154 // Skip methods that don't belong to the vftable of the current class,
3155 // e.g. each method that wasn't seen in any of the visited sub-bases
3156 // but overrides multiple methods of other sub-bases.
3157 continue;
3158 }
3159
3160 // If we got here, MD is a method not seen in any of the sub-bases or
3161 // it requires return adjustment. Insert the method info for this method.
3162 MethodInfo MI(VBIndex,
3163 HasRTTIComponent ? Components.size() - 1 : Components.size(),
3164 ReturnAdjustingThunk);
3165
3166 assert(!MethodInfoMap.count(MD) &&
3167 "Should not have method info for this method yet!");
3168 MethodInfoMap.insert(KV: std::make_pair(x&: MD, y&: MI));
3169
3170 // Check if this overrider needs a return adjustment.
3171 // We don't want to do this for pure virtual member functions.
3172 BaseOffset ReturnAdjustmentOffset;
3173 ReturnAdjustment ReturnAdjustment;
3174 if (!FinalOverriderMD->isPureVirtual()) {
3175 ReturnAdjustmentOffset =
3176 ComputeReturnAdjustmentBaseOffset(Context, DerivedMD: FinalOverriderMD, BaseMD: MD);
3177 }
3178 if (!ReturnAdjustmentOffset.isEmpty()) {
3179 ForceReturnAdjustmentMangling = true;
3180 ReturnAdjustment.NonVirtual =
3181 ReturnAdjustmentOffset.NonVirtualOffset.getQuantity();
3182 if (ReturnAdjustmentOffset.VirtualBase) {
3183 const ASTRecordLayout &DerivedLayout =
3184 Context.getASTRecordLayout(D: ReturnAdjustmentOffset.DerivedClass);
3185 ReturnAdjustment.Virtual.Microsoft.VBPtrOffset =
3186 DerivedLayout.getVBPtrOffset().getQuantity();
3187 ReturnAdjustment.Virtual.Microsoft.VBIndex =
3188 VTables.getVBTableIndex(Derived: ReturnAdjustmentOffset.DerivedClass,
3189 VBase: ReturnAdjustmentOffset.VirtualBase);
3190 }
3191 }
3192 auto ThisType = (OverriddenMD ? OverriddenMD : MD)->getThisType().getTypePtr();
3193 AddMethod(MD: FinalOverriderMD,
3194 TI: ThunkInfo(ThisAdjustmentOffset, ReturnAdjustment, ThisType,
3195 ForceReturnAdjustmentMangling ? MD : nullptr));
3196 }
3197}
3198
3199static void PrintBasePath(const VPtrInfo::BasePath &Path, raw_ostream &Out) {
3200 for (const CXXRecordDecl *Elem : llvm::reverse(C: Path)) {
3201 Out << "'";
3202 Elem->printQualifiedName(OS&: Out);
3203 Out << "' in ";
3204 }
3205}
3206
3207static void dumpMicrosoftThunkAdjustment(const ThunkInfo &TI, raw_ostream &Out,
3208 bool ContinueFirstLine) {
3209 const ReturnAdjustment &R = TI.Return;
3210 bool Multiline = false;
3211 const char *LinePrefix = "\n ";
3212 if (!R.isEmpty() || TI.Method) {
3213 if (!ContinueFirstLine)
3214 Out << LinePrefix;
3215 Out << "[return adjustment (to type '"
3216 << TI.Method->getReturnType().getCanonicalType() << "'): ";
3217 if (R.Virtual.Microsoft.VBPtrOffset)
3218 Out << "vbptr at offset " << R.Virtual.Microsoft.VBPtrOffset << ", ";
3219 if (R.Virtual.Microsoft.VBIndex)
3220 Out << "vbase #" << R.Virtual.Microsoft.VBIndex << ", ";
3221 Out << R.NonVirtual << " non-virtual]";
3222 Multiline = true;
3223 }
3224
3225 const ThisAdjustment &T = TI.This;
3226 if (!T.isEmpty()) {
3227 if (Multiline || !ContinueFirstLine)
3228 Out << LinePrefix;
3229 Out << "[this adjustment: ";
3230 if (!TI.This.Virtual.isEmpty()) {
3231 assert(T.Virtual.Microsoft.VtordispOffset < 0);
3232 Out << "vtordisp at " << T.Virtual.Microsoft.VtordispOffset << ", ";
3233 if (T.Virtual.Microsoft.VBPtrOffset) {
3234 Out << "vbptr at " << T.Virtual.Microsoft.VBPtrOffset
3235 << " to the left,";
3236 assert(T.Virtual.Microsoft.VBOffsetOffset > 0);
3237 Out << LinePrefix << " vboffset at "
3238 << T.Virtual.Microsoft.VBOffsetOffset << " in the vbtable, ";
3239 }
3240 }
3241 Out << T.NonVirtual << " non-virtual]";
3242 }
3243}
3244
3245void VFTableBuilder::dumpLayout(raw_ostream &Out) {
3246 Out << "VFTable for ";
3247 PrintBasePath(Path: WhichVFPtr.PathToIntroducingObject, Out);
3248 Out << "'";
3249 MostDerivedClass->printQualifiedName(OS&: Out);
3250 Out << "' (" << Components.size()
3251 << (Components.size() == 1 ? " entry" : " entries") << ").\n";
3252
3253 for (unsigned I = 0, E = Components.size(); I != E; ++I) {
3254 Out << llvm::format(Fmt: "%4d | ", Vals: I);
3255
3256 const VTableComponent &Component = Components[I];
3257
3258 // Dump the component.
3259 switch (Component.getKind()) {
3260 case VTableComponent::CK_RTTI:
3261 Component.getRTTIDecl()->printQualifiedName(OS&: Out);
3262 Out << " RTTI";
3263 break;
3264
3265 case VTableComponent::CK_FunctionPointer: {
3266 const CXXMethodDecl *MD = Component.getFunctionDecl();
3267
3268 // FIXME: Figure out how to print the real thunk type, since they can
3269 // differ in the return type.
3270 std::string Str = PredefinedExpr::ComputeName(
3271 IK: PredefinedIdentKind::PrettyFunctionNoVirtual, CurrentDecl: MD);
3272 Out << Str;
3273 if (MD->isPureVirtual())
3274 Out << " [pure]";
3275
3276 if (MD->isDeleted())
3277 Out << " [deleted]";
3278
3279 ThunkInfo Thunk = VTableThunks.lookup(Val: I);
3280 if (!Thunk.isEmpty())
3281 dumpMicrosoftThunkAdjustment(TI: Thunk, Out, /*ContinueFirstLine=*/false);
3282
3283 break;
3284 }
3285
3286 case VTableComponent::CK_DeletingDtorPointer: {
3287 const CXXDestructorDecl *DD = Component.getDestructorDecl();
3288
3289 DD->printQualifiedName(OS&: Out);
3290 Out << "() [scalar deleting]";
3291
3292 if (DD->isPureVirtual())
3293 Out << " [pure]";
3294
3295 ThunkInfo Thunk = VTableThunks.lookup(Val: I);
3296 if (!Thunk.isEmpty()) {
3297 assert(Thunk.Return.isEmpty() &&
3298 "No return adjustment needed for destructors!");
3299 dumpMicrosoftThunkAdjustment(TI: Thunk, Out, /*ContinueFirstLine=*/false);
3300 }
3301
3302 break;
3303 }
3304
3305 default:
3306 DiagnosticsEngine &Diags = Context.getDiagnostics();
3307 unsigned DiagID = Diags.getCustomDiagID(
3308 L: DiagnosticsEngine::Error,
3309 FormatString: "Unexpected vftable component type %0 for component number %1");
3310 Diags.Report(Loc: MostDerivedClass->getLocation(), DiagID)
3311 << I << Component.getKind();
3312 }
3313
3314 Out << '\n';
3315 }
3316
3317 Out << '\n';
3318
3319 if (!Thunks.empty()) {
3320 // We store the method names in a map to get a stable order.
3321 std::map<std::string, const CXXMethodDecl *> MethodNamesAndDecls;
3322
3323 for (const auto &I : Thunks) {
3324 const CXXMethodDecl *MD = I.first;
3325 std::string MethodName = PredefinedExpr::ComputeName(
3326 IK: PredefinedIdentKind::PrettyFunctionNoVirtual, CurrentDecl: MD);
3327
3328 MethodNamesAndDecls.insert(x: std::make_pair(x&: MethodName, y&: MD));
3329 }
3330
3331 for (const auto &MethodNameAndDecl : MethodNamesAndDecls) {
3332 const std::string &MethodName = MethodNameAndDecl.first;
3333 const CXXMethodDecl *MD = MethodNameAndDecl.second;
3334
3335 ThunkInfoVectorTy ThunksVector = Thunks[MD];
3336 llvm::stable_sort(Range&: ThunksVector, C: [](const ThunkInfo &LHS,
3337 const ThunkInfo &RHS) {
3338 // Keep different thunks with the same adjustments in the order they
3339 // were put into the vector.
3340 return std::tie(args: LHS.This, args: LHS.Return) < std::tie(args: RHS.This, args: RHS.Return);
3341 });
3342
3343 Out << "Thunks for '" << MethodName << "' (" << ThunksVector.size();
3344 Out << (ThunksVector.size() == 1 ? " entry" : " entries") << ").\n";
3345
3346 for (unsigned I = 0, E = ThunksVector.size(); I != E; ++I) {
3347 const ThunkInfo &Thunk = ThunksVector[I];
3348
3349 Out << llvm::format(Fmt: "%4d | ", Vals: I);
3350 dumpMicrosoftThunkAdjustment(TI: Thunk, Out, /*ContinueFirstLine=*/true);
3351 Out << '\n';
3352 }
3353
3354 Out << '\n';
3355 }
3356 }
3357
3358 Out.flush();
3359}
3360
3361static bool setsIntersect(const llvm::SmallPtrSet<const CXXRecordDecl *, 4> &A,
3362 ArrayRef<const CXXRecordDecl *> B) {
3363 for (const CXXRecordDecl *Decl : B) {
3364 if (A.count(Ptr: Decl))
3365 return true;
3366 }
3367 return false;
3368}
3369
3370static bool rebucketPaths(VPtrInfoVector &Paths);
3371
3372/// Produces MSVC-compatible vbtable data. The symbols produced by this
3373/// algorithm match those produced by MSVC 2012 and newer, which is different
3374/// from MSVC 2010.
3375///
3376/// MSVC 2012 appears to minimize the vbtable names using the following
3377/// algorithm. First, walk the class hierarchy in the usual order, depth first,
3378/// left to right, to find all of the subobjects which contain a vbptr field.
3379/// Visiting each class node yields a list of inheritance paths to vbptrs. Each
3380/// record with a vbptr creates an initially empty path.
3381///
3382/// To combine paths from child nodes, the paths are compared to check for
3383/// ambiguity. Paths are "ambiguous" if multiple paths have the same set of
3384/// components in the same order. Each group of ambiguous paths is extended by
3385/// appending the class of the base from which it came. If the current class
3386/// node produced an ambiguous path, its path is extended with the current class.
3387/// After extending paths, MSVC again checks for ambiguity, and extends any
3388/// ambiguous path which wasn't already extended. Because each node yields an
3389/// unambiguous set of paths, MSVC doesn't need to extend any path more than once
3390/// to produce an unambiguous set of paths.
3391///
3392/// TODO: Presumably vftables use the same algorithm.
3393void MicrosoftVTableContext::computeVTablePaths(bool ForVBTables,
3394 const CXXRecordDecl *RD,
3395 VPtrInfoVector &Paths) {
3396 assert(Paths.empty());
3397 const ASTRecordLayout &Layout = Context.getASTRecordLayout(D: RD);
3398
3399 // Base case: this subobject has its own vptr.
3400 if (ForVBTables ? Layout.hasOwnVBPtr() : Layout.hasOwnVFPtr())
3401 Paths.push_back(Elt: std::make_unique<VPtrInfo>(args&: RD));
3402
3403 // Recursive case: get all the vbtables from our bases and remove anything
3404 // that shares a virtual base.
3405 llvm::SmallPtrSet<const CXXRecordDecl*, 4> VBasesSeen;
3406 for (const auto &B : RD->bases()) {
3407 const CXXRecordDecl *Base = B.getType()->getAsCXXRecordDecl();
3408 if (B.isVirtual() && VBasesSeen.count(Ptr: Base))
3409 continue;
3410
3411 if (!Base->isDynamicClass())
3412 continue;
3413
3414 const VPtrInfoVector &BasePaths =
3415 ForVBTables ? enumerateVBTables(RD: Base) : getVFPtrOffsets(RD: Base);
3416
3417 for (const std::unique_ptr<VPtrInfo> &BaseInfo : BasePaths) {
3418 // Don't include the path if it goes through a virtual base that we've
3419 // already included.
3420 if (setsIntersect(A: VBasesSeen, B: BaseInfo->ContainingVBases))
3421 continue;
3422
3423 // Copy the path and adjust it as necessary.
3424 auto P = std::make_unique<VPtrInfo>(args&: *BaseInfo);
3425
3426 // We mangle Base into the path if the path would've been ambiguous and it
3427 // wasn't already extended with Base.
3428 if (P->MangledPath.empty() || P->MangledPath.back() != Base)
3429 P->NextBaseToMangle = Base;
3430
3431 // Keep track of which vtable the derived class is going to extend with
3432 // new methods or bases. We append to either the vftable of our primary
3433 // base, or the first non-virtual base that has a vbtable.
3434 if (P->ObjectWithVPtr == Base &&
3435 Base == (ForVBTables ? Layout.getBaseSharingVBPtr()
3436 : Layout.getPrimaryBase()))
3437 P->ObjectWithVPtr = RD;
3438
3439 // Keep track of the full adjustment from the MDC to this vtable. The
3440 // adjustment is captured by an optional vbase and a non-virtual offset.
3441 if (B.isVirtual())
3442 P->ContainingVBases.push_back(Elt: Base);
3443 else if (P->ContainingVBases.empty())
3444 P->NonVirtualOffset += Layout.getBaseClassOffset(Base);
3445
3446 // Update the full offset in the MDC.
3447 P->FullOffsetInMDC = P->NonVirtualOffset;
3448 if (const CXXRecordDecl *VB = P->getVBaseWithVPtr())
3449 P->FullOffsetInMDC += Layout.getVBaseClassOffset(VBase: VB);
3450
3451 Paths.push_back(Elt: std::move(P));
3452 }
3453
3454 if (B.isVirtual())
3455 VBasesSeen.insert(Ptr: Base);
3456
3457 // After visiting any direct base, we've transitively visited all of its
3458 // morally virtual bases.
3459 for (const auto &VB : Base->vbases())
3460 VBasesSeen.insert(Ptr: VB.getType()->getAsCXXRecordDecl());
3461 }
3462
3463 // Sort the paths into buckets, and if any of them are ambiguous, extend all
3464 // paths in ambiguous buckets.
3465 bool Changed = true;
3466 while (Changed)
3467 Changed = rebucketPaths(Paths);
3468}
3469
3470static bool extendPath(VPtrInfo &P) {
3471 if (P.NextBaseToMangle) {
3472 P.MangledPath.push_back(Elt: P.NextBaseToMangle);
3473 P.NextBaseToMangle = nullptr;// Prevent the path from being extended twice.
3474 return true;
3475 }
3476 return false;
3477}
3478
3479static bool rebucketPaths(VPtrInfoVector &Paths) {
3480 // What we're essentially doing here is bucketing together ambiguous paths.
3481 // Any bucket with more than one path in it gets extended by NextBase, which
3482 // is usually the direct base of the inherited the vbptr. This code uses a
3483 // sorted vector to implement a multiset to form the buckets. Note that the
3484 // ordering is based on pointers, but it doesn't change our output order. The
3485 // current algorithm is designed to match MSVC 2012's names.
3486 llvm::SmallVector<std::reference_wrapper<VPtrInfo>, 2> PathsSorted(
3487 llvm::make_pointee_range(Range&: Paths));
3488 llvm::sort(C&: PathsSorted, Comp: [](const VPtrInfo &LHS, const VPtrInfo &RHS) {
3489 return LHS.MangledPath < RHS.MangledPath;
3490 });
3491 bool Changed = false;
3492 for (size_t I = 0, E = PathsSorted.size(); I != E;) {
3493 // Scan forward to find the end of the bucket.
3494 size_t BucketStart = I;
3495 do {
3496 ++I;
3497 } while (I != E &&
3498 PathsSorted[BucketStart].get().MangledPath ==
3499 PathsSorted[I].get().MangledPath);
3500
3501 // If this bucket has multiple paths, extend them all.
3502 if (I - BucketStart > 1) {
3503 for (size_t II = BucketStart; II != I; ++II)
3504 Changed |= extendPath(P&: PathsSorted[II]);
3505 assert(Changed && "no paths were extended to fix ambiguity");
3506 }
3507 }
3508 return Changed;
3509}
3510
3511MicrosoftVTableContext::~MicrosoftVTableContext() {}
3512
3513namespace {
3514typedef llvm::SetVector<BaseSubobject, std::vector<BaseSubobject>,
3515 llvm::DenseSet<BaseSubobject>> FullPathTy;
3516}
3517
3518// This recursive function finds all paths from a subobject centered at
3519// (RD, Offset) to the subobject located at IntroducingObject.
3520static void findPathsToSubobject(ASTContext &Context,
3521 const ASTRecordLayout &MostDerivedLayout,
3522 const CXXRecordDecl *RD, CharUnits Offset,
3523 BaseSubobject IntroducingObject,
3524 FullPathTy &FullPath,
3525 std::list<FullPathTy> &Paths) {
3526 if (BaseSubobject(RD, Offset) == IntroducingObject) {
3527 Paths.push_back(x: FullPath);
3528 return;
3529 }
3530
3531 const ASTRecordLayout &Layout = Context.getASTRecordLayout(D: RD);
3532
3533 for (const CXXBaseSpecifier &BS : RD->bases()) {
3534 const CXXRecordDecl *Base = BS.getType()->getAsCXXRecordDecl();
3535 CharUnits NewOffset = BS.isVirtual()
3536 ? MostDerivedLayout.getVBaseClassOffset(VBase: Base)
3537 : Offset + Layout.getBaseClassOffset(Base);
3538 FullPath.insert(X: BaseSubobject(Base, NewOffset));
3539 findPathsToSubobject(Context, MostDerivedLayout, RD: Base, Offset: NewOffset,
3540 IntroducingObject, FullPath, Paths);
3541 FullPath.pop_back();
3542 }
3543}
3544
3545// Return the paths which are not subsets of other paths.
3546static void removeRedundantPaths(std::list<FullPathTy> &FullPaths) {
3547 FullPaths.remove_if(pred: [&](const FullPathTy &SpecificPath) {
3548 for (const FullPathTy &OtherPath : FullPaths) {
3549 if (&SpecificPath == &OtherPath)
3550 continue;
3551 if (llvm::all_of(Range: SpecificPath, P: [&](const BaseSubobject &BSO) {
3552 return OtherPath.contains(key: BSO);
3553 })) {
3554 return true;
3555 }
3556 }
3557 return false;
3558 });
3559}
3560
3561static CharUnits getOffsetOfFullPath(ASTContext &Context,
3562 const CXXRecordDecl *RD,
3563 const FullPathTy &FullPath) {
3564 const ASTRecordLayout &MostDerivedLayout =
3565 Context.getASTRecordLayout(D: RD);
3566 CharUnits Offset = CharUnits::fromQuantity(Quantity: -1);
3567 for (const BaseSubobject &BSO : FullPath) {
3568 const CXXRecordDecl *Base = BSO.getBase();
3569 // The first entry in the path is always the most derived record, skip it.
3570 if (Base == RD) {
3571 assert(Offset.getQuantity() == -1);
3572 Offset = CharUnits::Zero();
3573 continue;
3574 }
3575 assert(Offset.getQuantity() != -1);
3576 const ASTRecordLayout &Layout = Context.getASTRecordLayout(D: RD);
3577 // While we know which base has to be traversed, we don't know if that base
3578 // was a virtual base.
3579 const CXXBaseSpecifier *BaseBS = std::find_if(
3580 first: RD->bases_begin(), last: RD->bases_end(), pred: [&](const CXXBaseSpecifier &BS) {
3581 return BS.getType()->getAsCXXRecordDecl() == Base;
3582 });
3583 Offset = BaseBS->isVirtual() ? MostDerivedLayout.getVBaseClassOffset(VBase: Base)
3584 : Offset + Layout.getBaseClassOffset(Base);
3585 RD = Base;
3586 }
3587 return Offset;
3588}
3589
3590// We want to select the path which introduces the most covariant overrides. If
3591// two paths introduce overrides which the other path doesn't contain, issue a
3592// diagnostic.
3593static const FullPathTy *selectBestPath(ASTContext &Context,
3594 const CXXRecordDecl *RD,
3595 const VPtrInfo &Info,
3596 std::list<FullPathTy> &FullPaths) {
3597 // Handle some easy cases first.
3598 if (FullPaths.empty())
3599 return nullptr;
3600 if (FullPaths.size() == 1)
3601 return &FullPaths.front();
3602
3603 const FullPathTy *BestPath = nullptr;
3604 typedef std::set<const CXXMethodDecl *> OverriderSetTy;
3605 OverriderSetTy LastOverrides;
3606 for (const FullPathTy &SpecificPath : FullPaths) {
3607 assert(!SpecificPath.empty());
3608 OverriderSetTy CurrentOverrides;
3609 const CXXRecordDecl *TopLevelRD = SpecificPath.begin()->getBase();
3610 // Find the distance from the start of the path to the subobject with the
3611 // VPtr.
3612 CharUnits BaseOffset =
3613 getOffsetOfFullPath(Context, RD: TopLevelRD, FullPath: SpecificPath);
3614 FinalOverriders Overriders(TopLevelRD, CharUnits::Zero(), TopLevelRD);
3615 for (const CXXMethodDecl *MD : Info.IntroducingObject->methods()) {
3616 if (!MicrosoftVTableContext::hasVtableSlot(MD))
3617 continue;
3618 FinalOverriders::OverriderInfo OI =
3619 Overriders.getOverrider(MD: MD->getCanonicalDecl(), BaseOffset);
3620 const CXXMethodDecl *OverridingMethod = OI.Method;
3621 // Only overriders which have a return adjustment introduce problematic
3622 // thunks.
3623 if (ComputeReturnAdjustmentBaseOffset(Context, DerivedMD: OverridingMethod, BaseMD: MD)
3624 .isEmpty())
3625 continue;
3626 // It's possible that the overrider isn't in this path. If so, skip it
3627 // because this path didn't introduce it.
3628 const CXXRecordDecl *OverridingParent = OverridingMethod->getParent();
3629 if (llvm::none_of(Range: SpecificPath, P: [&](const BaseSubobject &BSO) {
3630 return BSO.getBase() == OverridingParent;
3631 }))
3632 continue;
3633 CurrentOverrides.insert(x: OverridingMethod);
3634 }
3635 OverriderSetTy NewOverrides =
3636 llvm::set_difference(S1: CurrentOverrides, S2: LastOverrides);
3637 if (NewOverrides.empty())
3638 continue;
3639 OverriderSetTy MissingOverrides =
3640 llvm::set_difference(S1: LastOverrides, S2: CurrentOverrides);
3641 if (MissingOverrides.empty()) {
3642 // This path is a strict improvement over the last path, let's use it.
3643 BestPath = &SpecificPath;
3644 std::swap(x&: CurrentOverrides, y&: LastOverrides);
3645 } else {
3646 // This path introduces an overrider with a conflicting covariant thunk.
3647 DiagnosticsEngine &Diags = Context.getDiagnostics();
3648 const CXXMethodDecl *CovariantMD = *NewOverrides.begin();
3649 const CXXMethodDecl *ConflictMD = *MissingOverrides.begin();
3650 Diags.Report(Loc: RD->getLocation(), DiagID: diag::err_vftable_ambiguous_component)
3651 << RD;
3652 Diags.Report(Loc: CovariantMD->getLocation(), DiagID: diag::note_covariant_thunk)
3653 << CovariantMD;
3654 Diags.Report(Loc: ConflictMD->getLocation(), DiagID: diag::note_covariant_thunk)
3655 << ConflictMD;
3656 }
3657 }
3658 // Go with the path that introduced the most covariant overrides. If there is
3659 // no such path, pick the first path.
3660 return BestPath ? BestPath : &FullPaths.front();
3661}
3662
3663static void computeFullPathsForVFTables(ASTContext &Context,
3664 const CXXRecordDecl *RD,
3665 VPtrInfoVector &Paths) {
3666 const ASTRecordLayout &MostDerivedLayout = Context.getASTRecordLayout(D: RD);
3667 FullPathTy FullPath;
3668 std::list<FullPathTy> FullPaths;
3669 for (const std::unique_ptr<VPtrInfo>& Info : Paths) {
3670 findPathsToSubobject(
3671 Context, MostDerivedLayout, RD, Offset: CharUnits::Zero(),
3672 IntroducingObject: BaseSubobject(Info->IntroducingObject, Info->FullOffsetInMDC), FullPath,
3673 Paths&: FullPaths);
3674 FullPath.clear();
3675 removeRedundantPaths(FullPaths);
3676 Info->PathToIntroducingObject.clear();
3677 if (const FullPathTy *BestPath =
3678 selectBestPath(Context, RD, Info: *Info, FullPaths))
3679 for (const BaseSubobject &BSO : *BestPath)
3680 Info->PathToIntroducingObject.push_back(Elt: BSO.getBase());
3681 FullPaths.clear();
3682 }
3683}
3684
3685static bool vfptrIsEarlierInMDC(const ASTRecordLayout &Layout,
3686 const MethodVFTableLocation &LHS,
3687 const MethodVFTableLocation &RHS) {
3688 CharUnits L = LHS.VFPtrOffset;
3689 CharUnits R = RHS.VFPtrOffset;
3690 if (LHS.VBase)
3691 L += Layout.getVBaseClassOffset(VBase: LHS.VBase);
3692 if (RHS.VBase)
3693 R += Layout.getVBaseClassOffset(VBase: RHS.VBase);
3694 return L < R;
3695}
3696
3697void MicrosoftVTableContext::computeVTableRelatedInformation(
3698 const CXXRecordDecl *RD) {
3699 assert(RD->isDynamicClass());
3700
3701 // Check if we've computed this information before.
3702 if (VFPtrLocations.count(Val: RD))
3703 return;
3704
3705 const VTableLayout::AddressPointsMapTy EmptyAddressPointsMap;
3706
3707 {
3708 auto VFPtrs = std::make_unique<VPtrInfoVector>();
3709 computeVTablePaths(/*ForVBTables=*/false, RD, Paths&: *VFPtrs);
3710 computeFullPathsForVFTables(Context, RD, Paths&: *VFPtrs);
3711 VFPtrLocations[RD] = std::move(VFPtrs);
3712 }
3713
3714 MethodVFTableLocationsTy NewMethodLocations;
3715 for (const std::unique_ptr<VPtrInfo> &VFPtr : *VFPtrLocations[RD]) {
3716 VFTableBuilder Builder(*this, RD, *VFPtr);
3717
3718 VFTableIdTy id(RD, VFPtr->FullOffsetInMDC);
3719 assert(VFTableLayouts.count(id) == 0);
3720 SmallVector<VTableLayout::VTableThunkTy, 1> VTableThunks(
3721 Builder.vtable_thunks_begin(), Builder.vtable_thunks_end());
3722 VFTableLayouts[id] = std::make_unique<VTableLayout>(
3723 args: ArrayRef<size_t>{0}, args: Builder.vtable_components(), args&: VTableThunks,
3724 args: EmptyAddressPointsMap);
3725 Thunks.insert(I: Builder.thunks_begin(), E: Builder.thunks_end());
3726
3727 const ASTRecordLayout &Layout = Context.getASTRecordLayout(D: RD);
3728 for (const auto &Loc : Builder.vtable_locations()) {
3729 auto Insert = NewMethodLocations.insert(KV: Loc);
3730 if (!Insert.second) {
3731 const MethodVFTableLocation &NewLoc = Loc.second;
3732 MethodVFTableLocation &OldLoc = Insert.first->second;
3733 if (vfptrIsEarlierInMDC(Layout, LHS: NewLoc, RHS: OldLoc))
3734 OldLoc = NewLoc;
3735 }
3736 }
3737 }
3738
3739 MethodVFTableLocations.insert_range(R&: NewMethodLocations);
3740 if (Context.getLangOpts().DumpVTableLayouts)
3741 dumpMethodLocations(RD, NewMethods: NewMethodLocations, llvm::outs());
3742}
3743
3744void MicrosoftVTableContext::dumpMethodLocations(
3745 const CXXRecordDecl *RD, const MethodVFTableLocationsTy &NewMethods,
3746 raw_ostream &Out) {
3747 // Compute the vtable indices for all the member functions.
3748 // Store them in a map keyed by the location so we'll get a sorted table.
3749 std::map<MethodVFTableLocation, std::string> IndicesMap;
3750 bool HasNonzeroOffset = false;
3751
3752 for (const auto &I : NewMethods) {
3753 const CXXMethodDecl *MD = cast<const CXXMethodDecl>(Val: I.first.getDecl());
3754 assert(hasVtableSlot(MD));
3755
3756 std::string MethodName = PredefinedExpr::ComputeName(
3757 IK: PredefinedIdentKind::PrettyFunctionNoVirtual, CurrentDecl: MD);
3758
3759 if (isa<CXXDestructorDecl>(Val: MD)) {
3760 IndicesMap[I.second] = MethodName + " [scalar deleting]";
3761 } else {
3762 IndicesMap[I.second] = MethodName;
3763 }
3764
3765 if (!I.second.VFPtrOffset.isZero() || I.second.VBTableIndex != 0)
3766 HasNonzeroOffset = true;
3767 }
3768
3769 // Print the vtable indices for all the member functions.
3770 if (!IndicesMap.empty()) {
3771 Out << "VFTable indices for ";
3772 Out << "'";
3773 RD->printQualifiedName(OS&: Out);
3774 Out << "' (" << IndicesMap.size()
3775 << (IndicesMap.size() == 1 ? " entry" : " entries") << ").\n";
3776
3777 CharUnits LastVFPtrOffset = CharUnits::fromQuantity(Quantity: -1);
3778 uint64_t LastVBIndex = 0;
3779 for (const auto &I : IndicesMap) {
3780 CharUnits VFPtrOffset = I.first.VFPtrOffset;
3781 uint64_t VBIndex = I.first.VBTableIndex;
3782 if (HasNonzeroOffset &&
3783 (VFPtrOffset != LastVFPtrOffset || VBIndex != LastVBIndex)) {
3784 assert(VBIndex > LastVBIndex || VFPtrOffset > LastVFPtrOffset);
3785 Out << " -- accessible via ";
3786 if (VBIndex)
3787 Out << "vbtable index " << VBIndex << ", ";
3788 Out << "vfptr at offset " << VFPtrOffset.getQuantity() << " --\n";
3789 LastVFPtrOffset = VFPtrOffset;
3790 LastVBIndex = VBIndex;
3791 }
3792
3793 uint64_t VTableIndex = I.first.Index;
3794 const std::string &MethodName = I.second;
3795 Out << llvm::format(Fmt: "%4" PRIu64 " | ", Vals: VTableIndex) << MethodName << '\n';
3796 }
3797 Out << '\n';
3798 }
3799
3800 Out.flush();
3801}
3802
3803const VirtualBaseInfo &MicrosoftVTableContext::computeVBTableRelatedInformation(
3804 const CXXRecordDecl *RD) {
3805 VirtualBaseInfo *VBI;
3806
3807 {
3808 // Get or create a VBI for RD. Don't hold a reference to the DenseMap cell,
3809 // as it may be modified and rehashed under us.
3810 std::unique_ptr<VirtualBaseInfo> &Entry = VBaseInfo[RD];
3811 if (Entry)
3812 return *Entry;
3813 Entry = std::make_unique<VirtualBaseInfo>();
3814 VBI = Entry.get();
3815 }
3816
3817 computeVTablePaths(/*ForVBTables=*/true, RD, Paths&: VBI->VBPtrPaths);
3818
3819 // First, see if the Derived class shared the vbptr with a non-virtual base.
3820 const ASTRecordLayout &Layout = Context.getASTRecordLayout(D: RD);
3821 if (const CXXRecordDecl *VBPtrBase = Layout.getBaseSharingVBPtr()) {
3822 // If the Derived class shares the vbptr with a non-virtual base, the shared
3823 // virtual bases come first so that the layout is the same.
3824 const VirtualBaseInfo &BaseInfo =
3825 computeVBTableRelatedInformation(RD: VBPtrBase);
3826 VBI->VBTableIndices.insert_range(R: BaseInfo.VBTableIndices);
3827 }
3828
3829 // New vbases are added to the end of the vbtable.
3830 // Skip the self entry and vbases visited in the non-virtual base, if any.
3831 unsigned VBTableIndex = 1 + VBI->VBTableIndices.size();
3832 for (const auto &VB : RD->vbases()) {
3833 const CXXRecordDecl *CurVBase = VB.getType()->getAsCXXRecordDecl();
3834 if (VBI->VBTableIndices.try_emplace(Key: CurVBase, Args&: VBTableIndex).second)
3835 ++VBTableIndex;
3836 }
3837
3838 return *VBI;
3839}
3840
3841unsigned MicrosoftVTableContext::getVBTableIndex(const CXXRecordDecl *Derived,
3842 const CXXRecordDecl *VBase) {
3843 const VirtualBaseInfo &VBInfo = computeVBTableRelatedInformation(RD: Derived);
3844 assert(VBInfo.VBTableIndices.count(VBase));
3845 return VBInfo.VBTableIndices.find(Val: VBase)->second;
3846}
3847
3848const VPtrInfoVector &
3849MicrosoftVTableContext::enumerateVBTables(const CXXRecordDecl *RD) {
3850 return computeVBTableRelatedInformation(RD).VBPtrPaths;
3851}
3852
3853const VPtrInfoVector &
3854MicrosoftVTableContext::getVFPtrOffsets(const CXXRecordDecl *RD) {
3855 computeVTableRelatedInformation(RD);
3856
3857 assert(VFPtrLocations.count(RD) && "Couldn't find vfptr locations");
3858 return *VFPtrLocations[RD];
3859}
3860
3861const VTableLayout &
3862MicrosoftVTableContext::getVFTableLayout(const CXXRecordDecl *RD,
3863 CharUnits VFPtrOffset) {
3864 computeVTableRelatedInformation(RD);
3865
3866 VFTableIdTy id(RD, VFPtrOffset);
3867 assert(VFTableLayouts.count(id) && "Couldn't find a VFTable at this offset");
3868 return *VFTableLayouts[id];
3869}
3870
3871MethodVFTableLocation
3872MicrosoftVTableContext::getMethodVFTableLocation(GlobalDecl GD) {
3873 assert(hasVtableSlot(cast<CXXMethodDecl>(GD.getDecl())) &&
3874 "Only use this method for virtual methods or dtors");
3875 if (isa<CXXDestructorDecl>(Val: GD.getDecl()))
3876 assert(GD.getDtorType() == Dtor_Deleting);
3877
3878 GD = GD.getCanonicalDecl();
3879
3880 MethodVFTableLocationsTy::iterator I = MethodVFTableLocations.find(Val: GD);
3881 if (I != MethodVFTableLocations.end())
3882 return I->second;
3883
3884 const CXXRecordDecl *RD = cast<CXXMethodDecl>(Val: GD.getDecl())->getParent();
3885
3886 computeVTableRelatedInformation(RD);
3887
3888 I = MethodVFTableLocations.find(Val: GD);
3889 assert(I != MethodVFTableLocations.end() && "Did not find index!");
3890 return I->second;
3891}
3892