clang 8.0.0

VTableBuilder.cpp
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1 //===--- VTableBuilder.cpp - C++ vtable layout builder --------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This contains code dealing with generation of the layout of virtual tables.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "clang/AST/VTableBuilder.h"
15 #include "clang/AST/ASTContext.h"
16 #include "clang/AST/ASTDiagnostic.h"
17 #include "clang/AST/CXXInheritance.h"
18 #include "clang/AST/RecordLayout.h"
19 #include "clang/Basic/TargetInfo.h"
20 #include "llvm/ADT/SetOperations.h"
21 #include "llvm/ADT/SmallPtrSet.h"
22 #include "llvm/Support/Format.h"
23 #include "llvm/Support/raw_ostream.h"
24 #include <algorithm>
25 #include <cstdio>
26
27 using namespace clang;
28
29 #define DUMP_OVERRIDERS 0
30
31 namespace {
32
33 /// BaseOffset - Represents an offset from a derived class to a direct or
34 /// indirect base class.
35 struct BaseOffset {
36 /// DerivedClass - The derived class.
37 const CXXRecordDecl *DerivedClass;
38
39 /// VirtualBase - If the path from the derived class to the base class
40 /// involves virtual base classes, this holds the declaration of the last
41 /// virtual base in this path (i.e. closest to the base class).
42 const CXXRecordDecl *VirtualBase;
43
44 /// NonVirtualOffset - The offset from the derived class to the base class.
45 /// (Or the offset from the virtual base class to the base class, if the
46 /// path from the derived class to the base class involves a virtual base
47 /// class.
48 CharUnits NonVirtualOffset;
49
50 BaseOffset() : DerivedClass(nullptr), VirtualBase(nullptr),
51 NonVirtualOffset(CharUnits::Zero()) { }
52 BaseOffset(const CXXRecordDecl *DerivedClass,
53 const CXXRecordDecl *VirtualBase, CharUnits NonVirtualOffset)
54 : DerivedClass(DerivedClass), VirtualBase(VirtualBase),
55 NonVirtualOffset(NonVirtualOffset) { }
56
57 bool isEmpty() const { return NonVirtualOffset.isZero() && !VirtualBase; }
58 };
59
60 /// FinalOverriders - Contains the final overrider member functions for all
61 /// member functions in the base subobjects of a class.
62 class FinalOverriders {
63 public:
64 /// OverriderInfo - Information about a final overrider.
65 struct OverriderInfo {
66 /// Method - The method decl of the overrider.
67 const CXXMethodDecl *Method;
68
69 /// VirtualBase - The virtual base class subobject of this overrider.
70 /// Note that this records the closest derived virtual base class subobject.
71 const CXXRecordDecl *VirtualBase;
72
73 /// Offset - the base offset of the overrider's parent in the layout class.
74 CharUnits Offset;
75
76 OverriderInfo() : Method(nullptr), VirtualBase(nullptr),
77 Offset(CharUnits::Zero()) { }
78 };
79
80 private:
81 /// MostDerivedClass - The most derived class for which the final overriders
82 /// are stored.
83 const CXXRecordDecl *MostDerivedClass;
84
85 /// MostDerivedClassOffset - If we're building final overriders for a
86 /// construction vtable, this holds the offset from the layout class to the
87 /// most derived class.
88 const CharUnits MostDerivedClassOffset;
89
90 /// LayoutClass - The class we're using for layout information. Will be
91 /// different than the most derived class if the final overriders are for a
92 /// construction vtable.
93 const CXXRecordDecl *LayoutClass;
94
95 ASTContext &Context;
96
97 /// MostDerivedClassLayout - the AST record layout of the most derived class.
98 const ASTRecordLayout &MostDerivedClassLayout;
99
100 /// MethodBaseOffsetPairTy - Uniquely identifies a member function
101 /// in a base subobject.
102 typedef std::pair<const CXXMethodDecl *, CharUnits> MethodBaseOffsetPairTy;
103
104 typedef llvm::DenseMap<MethodBaseOffsetPairTy,
105 OverriderInfo> OverridersMapTy;
106
107 /// OverridersMap - The final overriders for all virtual member functions of
108 /// all the base subobjects of the most derived class.
109 OverridersMapTy OverridersMap;
110
111 /// SubobjectsToOffsetsMapTy - A mapping from a base subobject (represented
112 /// as a record decl and a subobject number) and its offsets in the most
113 /// derived class as well as the layout class.
114 typedef llvm::DenseMap<std::pair<const CXXRecordDecl *, unsigned>,
115 CharUnits> SubobjectOffsetMapTy;
116
117 typedef llvm::DenseMap<const CXXRecordDecl *, unsigned> SubobjectCountMapTy;
118
119 /// ComputeBaseOffsets - Compute the offsets for all base subobjects of the
120 /// given base.
121 void ComputeBaseOffsets(BaseSubobject Base, bool IsVirtual,
122 CharUnits OffsetInLayoutClass,
123 SubobjectOffsetMapTy &SubobjectOffsets,
124 SubobjectOffsetMapTy &SubobjectLayoutClassOffsets,
125 SubobjectCountMapTy &SubobjectCounts);
126
127 typedef llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBasesSetTy;
128
129 /// dump - dump the final overriders for a base subobject, and all its direct
130 /// and indirect base subobjects.
131 void dump(raw_ostream &Out, BaseSubobject Base,
132 VisitedVirtualBasesSetTy& VisitedVirtualBases);
133
134 public:
135 FinalOverriders(const CXXRecordDecl *MostDerivedClass,
136 CharUnits MostDerivedClassOffset,
137 const CXXRecordDecl *LayoutClass);
138
139 /// getOverrider - Get the final overrider for the given method declaration in
140 /// the subobject with the given base offset.
141 OverriderInfo getOverrider(const CXXMethodDecl *MD,
142 CharUnits BaseOffset) const {
143 assert(OverridersMap.count(std::make_pair(MD, BaseOffset)) &&
144 "Did not find overrider!");
145
146 return OverridersMap.lookup(std::make_pair(MD, BaseOffset));
147 }
148
149 /// dump - dump the final overriders.
150 void dump() {
151 VisitedVirtualBasesSetTy VisitedVirtualBases;
152 dump(llvm::errs(), BaseSubobject(MostDerivedClass, CharUnits::Zero()),
153 VisitedVirtualBases);
154 }
155
156 };
157
158 FinalOverriders::FinalOverriders(const CXXRecordDecl *MostDerivedClass,
159 CharUnits MostDerivedClassOffset,
160 const CXXRecordDecl *LayoutClass)
161 : MostDerivedClass(MostDerivedClass),
162 MostDerivedClassOffset(MostDerivedClassOffset), LayoutClass(LayoutClass),
163 Context(MostDerivedClass->getASTContext()),
164 MostDerivedClassLayout(Context.getASTRecordLayout(MostDerivedClass)) {
165
166 // Compute base offsets.
167 SubobjectOffsetMapTy SubobjectOffsets;
168 SubobjectOffsetMapTy SubobjectLayoutClassOffsets;
169 SubobjectCountMapTy SubobjectCounts;
170 ComputeBaseOffsets(BaseSubobject(MostDerivedClass, CharUnits::Zero()),
171 /*IsVirtual=*/false,
172 MostDerivedClassOffset,
173 SubobjectOffsets, SubobjectLayoutClassOffsets,
174 SubobjectCounts);
175
176 // Get the final overriders.
177 CXXFinalOverriderMap FinalOverriders;
178 MostDerivedClass->getFinalOverriders(FinalOverriders);
179
180 for (const auto &Overrider : FinalOverriders) {
181 const CXXMethodDecl *MD = Overrider.first;
182 const OverridingMethods &Methods = Overrider.second;
183
184 for (const auto &M : Methods) {
185 unsigned SubobjectNumber = M.first;
186 assert(SubobjectOffsets.count(std::make_pair(MD->getParent(),
187 SubobjectNumber)) &&
188 "Did not find subobject offset!");
189
190 CharUnits BaseOffset = SubobjectOffsets[std::make_pair(MD->getParent(),
191 SubobjectNumber)];
192
193 assert(M.second.size() == 1 && "Final overrider is not unique!");
194 const UniqueVirtualMethod &Method = M.second.front();
195
196 const CXXRecordDecl *OverriderRD = Method.Method->getParent();
197 assert(SubobjectLayoutClassOffsets.count(
198 std::make_pair(OverriderRD, Method.Subobject))
199 && "Did not find subobject offset!");
200 CharUnits OverriderOffset =
201 SubobjectLayoutClassOffsets[std::make_pair(OverriderRD,
202 Method.Subobject)];
203
204 OverriderInfo& Overrider = OverridersMap[std::make_pair(MD, BaseOffset)];
205 assert(!Overrider.Method && "Overrider should not exist yet!");
206
207 Overrider.Offset = OverriderOffset;
208 Overrider.Method = Method.Method;
209 Overrider.VirtualBase = Method.InVirtualSubobject;
210 }
211 }
212
213 #if DUMP_OVERRIDERS
214 // And dump them (for now).
215 dump();
216 #endif
217 }
218
219 static BaseOffset ComputeBaseOffset(const ASTContext &Context,
220 const CXXRecordDecl *DerivedRD,
221 const CXXBasePath &Path) {
222 CharUnits NonVirtualOffset = CharUnits::Zero();
223
224 unsigned NonVirtualStart = 0;
225 const CXXRecordDecl *VirtualBase = nullptr;
226
227 // First, look for the virtual base class.
228 for (int I = Path.size(), E = 0; I != E; --I) {
229 const CXXBasePathElement &Element = Path[I - 1];
230
231 if (Element.Base->isVirtual()) {
232 NonVirtualStart = I;
233 QualType VBaseType = Element.Base->getType();
234 VirtualBase = VBaseType->getAsCXXRecordDecl();
235 break;
236 }
237 }
238
239 // Now compute the non-virtual offset.
240 for (unsigned I = NonVirtualStart, E = Path.size(); I != E; ++I) {
241 const CXXBasePathElement &Element = Path[I];
242
243 // Check the base class offset.
244 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Element.Class);
245
246 const CXXRecordDecl *Base = Element.Base->getType()->getAsCXXRecordDecl();
247
248 NonVirtualOffset += Layout.getBaseClassOffset(Base);
249 }
250
251 // FIXME: This should probably use CharUnits or something. Maybe we should
252 // even change the base offsets in ASTRecordLayout to be specified in
253 // CharUnits.
254 return BaseOffset(DerivedRD, VirtualBase, NonVirtualOffset);
255
256 }
257
258 static BaseOffset ComputeBaseOffset(const ASTContext &Context,
259 const CXXRecordDecl *BaseRD,
260 const CXXRecordDecl *DerivedRD) {
261 CXXBasePaths Paths(/*FindAmbiguities=*/false,
262 /*RecordPaths=*/true, /*DetectVirtual=*/false);
263
264 if (!DerivedRD->isDerivedFrom(BaseRD, Paths))
265 llvm_unreachable("Class must be derived from the passed in base class!");
266
267 return ComputeBaseOffset(Context, DerivedRD, Paths.front());
268 }
269
270 static BaseOffset
271 ComputeReturnAdjustmentBaseOffset(ASTContext &Context,
272 const CXXMethodDecl *DerivedMD,
273 const CXXMethodDecl *BaseMD) {
274 const FunctionType *BaseFT = BaseMD->getType()->getAs<FunctionType>();
275 const FunctionType *DerivedFT = DerivedMD->getType()->getAs<FunctionType>();
276
277 // Canonicalize the return types.
278 CanQualType CanDerivedReturnType =
279 Context.getCanonicalType(DerivedFT->getReturnType());
280 CanQualType CanBaseReturnType =
281 Context.getCanonicalType(BaseFT->getReturnType());
282
283 assert(CanDerivedReturnType->getTypeClass() ==
284 CanBaseReturnType->getTypeClass() &&
285 "Types must have same type class!");
286
287 if (CanDerivedReturnType == CanBaseReturnType) {
288 // No adjustment needed.
289 return BaseOffset();
290 }
291
292 if (isa<ReferenceType>(CanDerivedReturnType)) {
293 CanDerivedReturnType =
294 CanDerivedReturnType->getAs<ReferenceType>()->getPointeeType();
295 CanBaseReturnType =
296 CanBaseReturnType->getAs<ReferenceType>()->getPointeeType();
297 } else if (isa<PointerType>(CanDerivedReturnType)) {
298 CanDerivedReturnType =
299 CanDerivedReturnType->getAs<PointerType>()->getPointeeType();
300 CanBaseReturnType =
301 CanBaseReturnType->getAs<PointerType>()->getPointeeType();
302 } else {
303 llvm_unreachable("Unexpected return type!");
304 }
305
306 // We need to compare unqualified types here; consider
307 // const T *Base::foo();
308 // T *Derived::foo();
309 if (CanDerivedReturnType.getUnqualifiedType() ==
310 CanBaseReturnType.getUnqualifiedType()) {
311 // No adjustment needed.
312 return BaseOffset();
313 }
314
315 const CXXRecordDecl *DerivedRD =
316 cast<CXXRecordDecl>(cast<RecordType>(CanDerivedReturnType)->getDecl());
317
318 const CXXRecordDecl *BaseRD =
319 cast<CXXRecordDecl>(cast<RecordType>(CanBaseReturnType)->getDecl());
320
321 return ComputeBaseOffset(Context, BaseRD, DerivedRD);
322 }
323
324 void
325 FinalOverriders::ComputeBaseOffsets(BaseSubobject Base, bool IsVirtual,
326 CharUnits OffsetInLayoutClass,
327 SubobjectOffsetMapTy &SubobjectOffsets,
328 SubobjectOffsetMapTy &SubobjectLayoutClassOffsets,
329 SubobjectCountMapTy &SubobjectCounts) {
330 const CXXRecordDecl *RD = Base.getBase();
331
332 unsigned SubobjectNumber = 0;
333 if (!IsVirtual)
334 SubobjectNumber = ++SubobjectCounts[RD];
335
336 // Set up the subobject to offset mapping.
337 assert(!SubobjectOffsets.count(std::make_pair(RD, SubobjectNumber))
338 && "Subobject offset already exists!");
339 assert(!SubobjectLayoutClassOffsets.count(std::make_pair(RD, SubobjectNumber))
340 && "Subobject offset already exists!");
341
342 SubobjectOffsets[std::make_pair(RD, SubobjectNumber)] = Base.getBaseOffset();
343 SubobjectLayoutClassOffsets[std::make_pair(RD, SubobjectNumber)] =
344 OffsetInLayoutClass;
345
346 // Traverse our bases.
347 for (const auto &B : RD->bases()) {
348 const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
349
350 CharUnits BaseOffset;
351 CharUnits BaseOffsetInLayoutClass;
352 if (B.isVirtual()) {
353 // Check if we've visited this virtual base before.
354 if (SubobjectOffsets.count(std::make_pair(BaseDecl, 0)))
355 continue;
356
357 const ASTRecordLayout &LayoutClassLayout =
358 Context.getASTRecordLayout(LayoutClass);
359
360 BaseOffset = MostDerivedClassLayout.getVBaseClassOffset(BaseDecl);
361 BaseOffsetInLayoutClass =
362 LayoutClassLayout.getVBaseClassOffset(BaseDecl);
363 } else {
364 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
365 CharUnits Offset = Layout.getBaseClassOffset(BaseDecl);
366
367 BaseOffset = Base.getBaseOffset() + Offset;
368 BaseOffsetInLayoutClass = OffsetInLayoutClass + Offset;
369 }
370
371 ComputeBaseOffsets(BaseSubobject(BaseDecl, BaseOffset),
372 B.isVirtual(), BaseOffsetInLayoutClass,
373 SubobjectOffsets, SubobjectLayoutClassOffsets,
374 SubobjectCounts);
375 }
376 }
377
378 void FinalOverriders::dump(raw_ostream &Out, BaseSubobject Base,
379 VisitedVirtualBasesSetTy &VisitedVirtualBases) {
380 const CXXRecordDecl *RD = Base.getBase();
381 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
382
383 for (const auto &B : RD->bases()) {
384 const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
385
386 // Ignore bases that don't have any virtual member functions.
387 if (!BaseDecl->isPolymorphic())
388 continue;
389
390 CharUnits BaseOffset;
391 if (B.isVirtual()) {
392 if (!VisitedVirtualBases.insert(BaseDecl).second) {
393 // We've visited this base before.
394 continue;
395 }
396
397 BaseOffset = MostDerivedClassLayout.getVBaseClassOffset(BaseDecl);
398 } else {
399 BaseOffset = Layout.getBaseClassOffset(BaseDecl) + Base.getBaseOffset();
400 }
401
402 dump(Out, BaseSubobject(BaseDecl, BaseOffset), VisitedVirtualBases);
403 }
404
405 Out << "Final overriders for (";
406 RD->printQualifiedName(Out);
407 Out << ", ";
408 Out << Base.getBaseOffset().getQuantity() << ")\n";
409
410 // Now dump the overriders for this base subobject.
411 for (const auto *MD : RD->methods()) {
412 if (!MD->isVirtual())
413 continue;
414 MD = MD->getCanonicalDecl();
415
416 OverriderInfo Overrider = getOverrider(MD, Base.getBaseOffset());
417
418 Out << " ";
419 MD->printQualifiedName(Out);
420 Out << " - (";
421 Overrider.Method->printQualifiedName(Out);
422 Out << ", " << Overrider.Offset.getQuantity() << ')';
423
424 BaseOffset Offset;
425 if (!Overrider.Method->isPure())
426 Offset = ComputeReturnAdjustmentBaseOffset(Context, Overrider.Method, MD);
427
428 if (!Offset.isEmpty()) {
429 Out << " [ret-adj: ";
430 if (Offset.VirtualBase) {
431 Offset.VirtualBase->printQualifiedName(Out);
432 Out << " vbase, ";
433 }
434
435 Out << Offset.NonVirtualOffset.getQuantity() << " nv]";
436 }
437
438 Out << "\n";
439 }
440 }
441
442 /// VCallOffsetMap - Keeps track of vcall offsets when building a vtable.
443 struct VCallOffsetMap {
444
445 typedef std::pair<const CXXMethodDecl *, CharUnits> MethodAndOffsetPairTy;
446
447 /// Offsets - Keeps track of methods and their offsets.
448 // FIXME: This should be a real map and not a vector.
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
456 public:
457 /// AddVCallOffset - Adds a vcall offset to the map. Returns true if the
458 /// add was successful, or false if there was already a member function with
459 /// the same signature in the map.
460 bool AddVCallOffset(const CXXMethodDecl *MD, CharUnits OffsetOffset);
461
462 /// getVCallOffsetOffset - Returns the vcall offset offset (relative to the
463 /// vtable address point) for the given virtual member function.
464 CharUnits getVCallOffsetOffset(const CXXMethodDecl *MD);
465
466 // empty - Return whether the offset map is empty or not.
467 bool empty() const { return Offsets.empty(); }
468 };
469
470 static bool HasSameVirtualSignature(const CXXMethodDecl *LHS,
471 const CXXMethodDecl *RHS) {
472 const FunctionProtoType *LT =
473 cast<FunctionProtoType>(LHS->getType().getCanonicalType());
474 const FunctionProtoType *RT =
475 cast<FunctionProtoType>(RHS->getType().getCanonicalType());
476
477 // Fast-path matches in the canonical types.
478 if (LT == RT) return true;
479
480 // Force the signatures to match. We can't rely on the overrides
481 // list here because there isn't necessarily an inheritance
482 // relationship between the two methods.
483 if (LT->getTypeQuals() != RT->getTypeQuals())
484 return false;
485 return LT->getParamTypes() == RT->getParamTypes();
486 }
487
488 bool VCallOffsetMap::MethodsCanShareVCallOffset(const CXXMethodDecl *LHS,
489 const CXXMethodDecl *RHS) {
490 assert(LHS->isVirtual() && "LHS must be virtual!");
491 assert(RHS->isVirtual() && "LHS must be virtual!");
492
493 // A destructor can share a vcall offset with another destructor.
494 if (isa<CXXDestructorDecl>(LHS))
495 return isa<CXXDestructorDecl>(RHS);
496
497 // FIXME: We need to check more things here.
498
499 // The methods must have the same name.
500 DeclarationName LHSName = LHS->getDeclName();
501 DeclarationName RHSName = RHS->getDeclName();
502 if (LHSName != RHSName)
503 return false;
504
505 // And the same signatures.
506 return HasSameVirtualSignature(LHS, RHS);
507 }
508
509 bool VCallOffsetMap::AddVCallOffset(const CXXMethodDecl *MD,
510 CharUnits OffsetOffset) {
511 // Check if we can reuse an offset.
512 for (const auto &OffsetPair : Offsets) {
513 if (MethodsCanShareVCallOffset(OffsetPair.first, MD))
514 return false;
515 }
516
517 // Add the offset.
518 Offsets.push_back(MethodAndOffsetPairTy(MD, OffsetOffset));
519 return true;
520 }
521
522 CharUnits VCallOffsetMap::getVCallOffsetOffset(const CXXMethodDecl *MD) {
523 // Look for an offset.
524 for (const auto &OffsetPair : Offsets) {
525 if (MethodsCanShareVCallOffset(OffsetPair.first, MD))
526 return OffsetPair.second;
527 }
528
529 llvm_unreachable("Should always find a vcall offset offset!");
530 }
531
532 /// VCallAndVBaseOffsetBuilder - Class for building vcall and vbase offsets.
533 class VCallAndVBaseOffsetBuilder {
534 public:
535 typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits>
536 VBaseOffsetOffsetsMapTy;
537
538 private:
539 /// MostDerivedClass - The most derived class for which we're building vcall
540 /// and vbase offsets.
541 const CXXRecordDecl *MostDerivedClass;
542
543 /// LayoutClass - The class we're using for layout information. Will be
544 /// different than the most derived class if we're building a construction
545 /// vtable.
546 const CXXRecordDecl *LayoutClass;
547
548 /// Context - The ASTContext which we will use for layout information.
549 ASTContext &Context;
550
551 /// Components - vcall and vbase offset components
552 typedef SmallVector<VTableComponent, 64> VTableComponentVectorTy;
553 VTableComponentVectorTy Components;
554
555 /// VisitedVirtualBases - Visited virtual bases.
556 llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBases;
557
558 /// VCallOffsets - Keeps track of vcall offsets.
559 VCallOffsetMap VCallOffsets;
560
561
562 /// VBaseOffsetOffsets - Contains the offsets of the virtual base offsets,
563 /// relative to the address point.
564 VBaseOffsetOffsetsMapTy VBaseOffsetOffsets;
565
566 /// FinalOverriders - The final overriders of the most derived class.
567 /// (Can be null when we're not building a vtable of the most derived class).
568 const FinalOverriders *Overriders;
569
570 /// AddVCallAndVBaseOffsets - Add vcall offsets and vbase offsets for the
571 /// given base subobject.
572 void AddVCallAndVBaseOffsets(BaseSubobject Base, bool BaseIsVirtual,
573 CharUnits RealBaseOffset);
574
575 /// AddVCallOffsets - Add vcall offsets for the given base subobject.
576 void AddVCallOffsets(BaseSubobject Base, CharUnits VBaseOffset);
577
578 /// AddVBaseOffsets - Add vbase offsets for the given class.
579 void AddVBaseOffsets(const CXXRecordDecl *Base,
580 CharUnits OffsetInLayoutClass);
581
582 /// getCurrentOffsetOffset - Get the current vcall or vbase offset offset in
583 /// chars, relative to the vtable address point.
584 CharUnits getCurrentOffsetOffset() const;
585
586 public:
587 VCallAndVBaseOffsetBuilder(const CXXRecordDecl *MostDerivedClass,
588 const CXXRecordDecl *LayoutClass,
589 const FinalOverriders *Overriders,
590 BaseSubobject Base, bool BaseIsVirtual,
591 CharUnits OffsetInLayoutClass)
592 : MostDerivedClass(MostDerivedClass), LayoutClass(LayoutClass),
593 Context(MostDerivedClass->getASTContext()), Overriders(Overriders) {
594
595 // Add vcall and vbase offsets.
596 AddVCallAndVBaseOffsets(Base, BaseIsVirtual, OffsetInLayoutClass);
597 }
598
599 /// Methods for iterating over the components.
600 typedef VTableComponentVectorTy::const_reverse_iterator const_iterator;
601 const_iterator components_begin() const { return Components.rbegin(); }
602 const_iterator components_end() const { return Components.rend(); }
603
604 const VCallOffsetMap &getVCallOffsets() const { return VCallOffsets; }
605 const VBaseOffsetOffsetsMapTy &getVBaseOffsetOffsets() const {
606 return VBaseOffsetOffsets;
607 }
608 };
609
610 void
611 VCallAndVBaseOffsetBuilder::AddVCallAndVBaseOffsets(BaseSubobject Base,
612 bool BaseIsVirtual,
613 CharUnits RealBaseOffset) {
614 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base.getBase());
615
616 // Itanium C++ ABI 2.5.2:
617 // ..in classes sharing a virtual table with a primary base class, the vcall
618 // and vbase offsets added by the derived class all come before the vcall
619 // and vbase offsets required by the base class, so that the latter may be
620 // laid out as required by the base class without regard to additions from
621 // the derived class(es).
622
623 // (Since we're emitting the vcall and vbase offsets in reverse order, we'll
624 // emit them for the primary base first).
625 if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
626 bool PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual();
627
628 CharUnits PrimaryBaseOffset;
629
630 // Get the base offset of the primary base.
631 if (PrimaryBaseIsVirtual) {
632 assert(Layout.getVBaseClassOffset(PrimaryBase).isZero() &&
633 "Primary vbase should have a zero offset!");
634
635 const ASTRecordLayout &MostDerivedClassLayout =
636 Context.getASTRecordLayout(MostDerivedClass);
637
638 PrimaryBaseOffset =
639 MostDerivedClassLayout.getVBaseClassOffset(PrimaryBase);
640 } else {
641 assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
642 "Primary base should have a zero offset!");
643
644 PrimaryBaseOffset = Base.getBaseOffset();
645 }
646
647 AddVCallAndVBaseOffsets(
648 BaseSubobject(PrimaryBase,PrimaryBaseOffset),
649 PrimaryBaseIsVirtual, RealBaseOffset);
650 }
651
652 AddVBaseOffsets(Base.getBase(), RealBaseOffset);
653
654 // We only want to add vcall offsets for virtual bases.
655 if (BaseIsVirtual)
656 AddVCallOffsets(Base, RealBaseOffset);
657 }
658
659 CharUnits VCallAndVBaseOffsetBuilder::getCurrentOffsetOffset() const {
660 // OffsetIndex is the index of this vcall or vbase offset, relative to the
661 // vtable address point. (We subtract 3 to account for the information just
662 // above the address point, the RTTI info, the offset to top, and the
663 // vcall offset itself).
664 int64_t OffsetIndex = -(int64_t)(3 + Components.size());
665
666 CharUnits PointerWidth =
667 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
668 CharUnits OffsetOffset = PointerWidth * OffsetIndex;
669 return OffsetOffset;
670 }
671
672 void VCallAndVBaseOffsetBuilder::AddVCallOffsets(BaseSubobject Base,
673 CharUnits VBaseOffset) {
674 const CXXRecordDecl *RD = Base.getBase();
675 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
676
677 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
678
679 // Handle the primary base first.
680 // We only want to add vcall offsets if the base is non-virtual; a virtual
681 // primary base will have its vcall and vbase offsets emitted already.
682 if (PrimaryBase && !Layout.isPrimaryBaseVirtual()) {
683 // Get the base offset of the primary base.
684 assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
685 "Primary base should have a zero offset!");
686
687 AddVCallOffsets(BaseSubobject(PrimaryBase, Base.getBaseOffset()),
688 VBaseOffset);
689 }
690
691 // Add the vcall offsets.
692 for (const auto *MD : RD->methods()) {
693 if (!MD->isVirtual())
694 continue;
695 MD = MD->getCanonicalDecl();
696
697 CharUnits OffsetOffset = getCurrentOffsetOffset();
698
699 // Don't add a vcall offset if we already have one for this member function
700 // signature.
701 if (!VCallOffsets.AddVCallOffset(MD, OffsetOffset))
702 continue;
703
704 CharUnits Offset = CharUnits::Zero();
705
706 if (Overriders) {
707 // Get the final overrider.
708 FinalOverriders::OverriderInfo Overrider =
709 Overriders->getOverrider(MD, Base.getBaseOffset());
710
711 /// The vcall offset is the offset from the virtual base to the object
712 /// where the function was overridden.
713 Offset = Overrider.Offset - VBaseOffset;
714 }
715
716 Components.push_back(
717 VTableComponent::MakeVCallOffset(Offset));
718 }
719
720 // And iterate over all non-virtual bases (ignoring the primary base).
721 for (const auto &B : RD->bases()) {
722 if (B.isVirtual())
723 continue;
724
725 const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
726 if (BaseDecl == PrimaryBase)
727 continue;
728
729 // Get the base offset of this base.
730 CharUnits BaseOffset = Base.getBaseOffset() +
731 Layout.getBaseClassOffset(BaseDecl);
732
733 AddVCallOffsets(BaseSubobject(BaseDecl, BaseOffset),
734 VBaseOffset);
735 }
736 }
737
738 void
739 VCallAndVBaseOffsetBuilder::AddVBaseOffsets(const CXXRecordDecl *RD,
740 CharUnits OffsetInLayoutClass) {
741 const ASTRecordLayout &LayoutClassLayout =
742 Context.getASTRecordLayout(LayoutClass);
743
744 // Add vbase offsets.
745 for (const auto &B : RD->bases()) {
746 const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
747
748 // Check if this is a virtual base that we haven't visited before.
749 if (B.isVirtual() && VisitedVirtualBases.insert(BaseDecl).second) {
750 CharUnits Offset =
751 LayoutClassLayout.getVBaseClassOffset(BaseDecl) - OffsetInLayoutClass;
752
753 // Add the vbase offset offset.
754 assert(!VBaseOffsetOffsets.count(BaseDecl) &&
755 "vbase offset offset already exists!");
756
757 CharUnits VBaseOffsetOffset = getCurrentOffsetOffset();
758 VBaseOffsetOffsets.insert(
759 std::make_pair(BaseDecl, VBaseOffsetOffset));
760
761 Components.push_back(
762 VTableComponent::MakeVBaseOffset(Offset));
763 }
764
765 // Check the base class looking for more vbase offsets.
766 AddVBaseOffsets(BaseDecl, OffsetInLayoutClass);
767 }
768 }
769
770 /// ItaniumVTableBuilder - Class for building vtable layout information.
771 class ItaniumVTableBuilder {
772 public:
773 /// PrimaryBasesSetVectorTy - A set vector of direct and indirect
774 /// primary bases.
775 typedef llvm::SmallSetVector<const CXXRecordDecl *, 8>
776 PrimaryBasesSetVectorTy;
777
778 typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits>
779 VBaseOffsetOffsetsMapTy;
780
781 typedef VTableLayout::AddressPointsMapTy AddressPointsMapTy;
782
783 typedef llvm::DenseMap<GlobalDecl, int64_t> MethodVTableIndicesTy;
784
785 private:
786 /// VTables - Global vtable information.
787 ItaniumVTableContext &VTables;
788
789 /// MostDerivedClass - The most derived class for which we're building this
790 /// vtable.
791 const CXXRecordDecl *MostDerivedClass;
792
793 /// MostDerivedClassOffset - If we're building a construction vtable, this
794 /// holds the offset from the layout class to the most derived class.
795 const CharUnits MostDerivedClassOffset;
796
797 /// MostDerivedClassIsVirtual - Whether the most derived class is a virtual
798 /// base. (This only makes sense when building a construction vtable).
799 bool MostDerivedClassIsVirtual;
800
801 /// LayoutClass - The class we're using for layout information. Will be
802 /// different than the most derived class if we're building a construction
803 /// vtable.
804 const CXXRecordDecl *LayoutClass;
805
806 /// Context - The ASTContext which we will use for layout information.
807 ASTContext &Context;
808
809 /// FinalOverriders - The final overriders of the most derived class.
810 const FinalOverriders Overriders;
811
812 /// VCallOffsetsForVBases - Keeps track of vcall offsets for the virtual
813 /// bases in this vtable.
814 llvm::DenseMap<const CXXRecordDecl *, VCallOffsetMap> VCallOffsetsForVBases;
815
816 /// VBaseOffsetOffsets - Contains the offsets of the virtual base offsets for
817 /// the most derived class.
818 VBaseOffsetOffsetsMapTy VBaseOffsetOffsets;
819
820 /// Components - The components of the vtable being built.
821 SmallVector<VTableComponent, 64> Components;
822
823 /// AddressPoints - Address points for the vtable being built.
824 AddressPointsMapTy AddressPoints;
825
826 /// MethodInfo - Contains information about a method in a vtable.
827 /// (Used for computing 'this' pointer adjustment thunks.
828 struct MethodInfo {
829 /// BaseOffset - The base offset of this method.
830 const CharUnits BaseOffset;
831
832 /// BaseOffsetInLayoutClass - The base offset in the layout class of this
833 /// method.
834 const CharUnits BaseOffsetInLayoutClass;
835
836 /// VTableIndex - The index in the vtable that this method has.
837 /// (For destructors, this is the index of the complete destructor).
838 const uint64_t VTableIndex;
839
840 MethodInfo(CharUnits BaseOffset, CharUnits BaseOffsetInLayoutClass,
841 uint64_t VTableIndex)
842 : BaseOffset(BaseOffset),
843 BaseOffsetInLayoutClass(BaseOffsetInLayoutClass),
844 VTableIndex(VTableIndex) { }
845
846 MethodInfo()
847 : BaseOffset(CharUnits::Zero()),
848 BaseOffsetInLayoutClass(CharUnits::Zero()),
849 VTableIndex(0) { }
850 };
851
852 typedef llvm::DenseMap<const CXXMethodDecl *, MethodInfo> MethodInfoMapTy;
853
854 /// MethodInfoMap - The information for all methods in the vtable we're
855 /// currently building.
856 MethodInfoMapTy MethodInfoMap;
857
858 /// MethodVTableIndices - Contains the index (relative to the vtable address
859 /// point) where the function pointer for a virtual function is stored.
860 MethodVTableIndicesTy MethodVTableIndices;
861
862 typedef llvm::DenseMap<uint64_t, ThunkInfo> VTableThunksMapTy;
863
864 /// VTableThunks - The thunks by vtable index in the vtable currently being
865 /// built.
866 VTableThunksMapTy VTableThunks;
867
868 typedef SmallVector<ThunkInfo, 1> ThunkInfoVectorTy;
869 typedef llvm::DenseMap<const CXXMethodDecl *, ThunkInfoVectorTy> ThunksMapTy;
870
871 /// Thunks - A map that contains all the thunks needed for all methods in the
872 /// most derived class for which the vtable is currently being built.
873 ThunksMapTy Thunks;
874
875 /// AddThunk - Add a thunk for the given method.
876 void AddThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk);
877
878 /// ComputeThisAdjustments - Compute the 'this' pointer adjustments for the
879 /// part of the vtable we're currently building.
880 void ComputeThisAdjustments();
881
882 typedef llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBasesSetTy;
883
884 /// PrimaryVirtualBases - All known virtual bases who are a primary base of
885 /// some other base.
886 VisitedVirtualBasesSetTy PrimaryVirtualBases;
887
888 /// ComputeReturnAdjustment - Compute the return adjustment given a return
889 /// adjustment base offset.
890 ReturnAdjustment ComputeReturnAdjustment(BaseOffset Offset);
891
892 /// ComputeThisAdjustmentBaseOffset - Compute the base offset for adjusting
893 /// the 'this' pointer from the base subobject to the derived subobject.
894 BaseOffset ComputeThisAdjustmentBaseOffset(BaseSubobject Base,
895 BaseSubobject Derived) const;
896
897 /// ComputeThisAdjustment - Compute the 'this' pointer adjustment for the
898 /// given virtual member function, its offset in the layout class and its
899 /// final overrider.
900 ThisAdjustment
901 ComputeThisAdjustment(const CXXMethodDecl *MD,
902 CharUnits BaseOffsetInLayoutClass,
903 FinalOverriders::OverriderInfo Overrider);
904
905 /// AddMethod - Add a single virtual member function to the vtable
906 /// components vector.
907 void AddMethod(const CXXMethodDecl *MD, ReturnAdjustment ReturnAdjustment);
908
909 /// IsOverriderUsed - Returns whether the overrider will ever be used in this
910 /// part of the vtable.
911 ///
912 /// Itanium C++ ABI 2.5.2:
913 ///
914 /// struct A { virtual void f(); };
915 /// struct B : virtual public A { int i; };
916 /// struct C : virtual public A { int j; };
917 /// struct D : public B, public C {};
918 ///
919 /// When B and C are declared, A is a primary base in each case, so although
920 /// vcall offsets are allocated in the A-in-B and A-in-C vtables, no this
921 /// adjustment is required and no thunk is generated. However, inside D
922 /// objects, A is no longer a primary base of C, so if we allowed calls to
923 /// C::f() to use the copy of A's vtable in the C subobject, we would need
924 /// to adjust this from C* to B::A*, which would require a third-party
925 /// thunk. Since we require that a call to C::f() first convert to A*,
926 /// C-in-D's copy of A's vtable is never referenced, so this is not
927 /// necessary.
928 bool IsOverriderUsed(const CXXMethodDecl *Overrider,
929 CharUnits BaseOffsetInLayoutClass,
930 const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
931 CharUnits FirstBaseOffsetInLayoutClass) const;
932
933
934 /// AddMethods - Add the methods of this base subobject and all its
935 /// primary bases to the vtable components vector.
936 void AddMethods(BaseSubobject Base, CharUnits BaseOffsetInLayoutClass,
937 const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
938 CharUnits FirstBaseOffsetInLayoutClass,
939 PrimaryBasesSetVectorTy &PrimaryBases);
940
941 // LayoutVTable - Layout the vtable for the given base class, including its
942 // secondary vtables and any vtables for virtual bases.
943 void LayoutVTable();
944
945 /// LayoutPrimaryAndSecondaryVTables - Layout the primary vtable for the
946 /// given base subobject, as well as all its secondary vtables.
947 ///
948 /// \param BaseIsMorallyVirtual whether the base subobject is a virtual base
949 /// or a direct or indirect base of a virtual base.
950 ///
951 /// \param BaseIsVirtualInLayoutClass - Whether the base subobject is virtual
952 /// in the layout class.
953 void LayoutPrimaryAndSecondaryVTables(BaseSubobject Base,
954 bool BaseIsMorallyVirtual,
955 bool BaseIsVirtualInLayoutClass,
956 CharUnits OffsetInLayoutClass);
957
958 /// LayoutSecondaryVTables - Layout the secondary vtables for the given base
959 /// subobject.
960 ///
961 /// \param BaseIsMorallyVirtual whether the base subobject is a virtual base
962 /// or a direct or indirect base of a virtual base.
963 void LayoutSecondaryVTables(BaseSubobject Base, bool BaseIsMorallyVirtual,
964 CharUnits OffsetInLayoutClass);
965
966 /// DeterminePrimaryVirtualBases - Determine the primary virtual bases in this
967 /// class hierarchy.
968 void DeterminePrimaryVirtualBases(const CXXRecordDecl *RD,
969 CharUnits OffsetInLayoutClass,
970 VisitedVirtualBasesSetTy &VBases);
971
972 /// LayoutVTablesForVirtualBases - Layout vtables for all virtual bases of the
973 /// given base (excluding any primary bases).
974 void LayoutVTablesForVirtualBases(const CXXRecordDecl *RD,
975 VisitedVirtualBasesSetTy &VBases);
976
977 /// isBuildingConstructionVTable - Return whether this vtable builder is
978 /// building a construction vtable.
979 bool isBuildingConstructorVTable() const {
980 return MostDerivedClass != LayoutClass;
981 }
982
983 public:
984 /// Component indices of the first component of each of the vtables in the
985 /// vtable group.
986 SmallVector<size_t, 4> VTableIndices;
987
988 ItaniumVTableBuilder(ItaniumVTableContext &VTables,
989 const CXXRecordDecl *MostDerivedClass,
990 CharUnits MostDerivedClassOffset,
991 bool MostDerivedClassIsVirtual,
992 const CXXRecordDecl *LayoutClass)
993 : VTables(VTables), MostDerivedClass(MostDerivedClass),
994 MostDerivedClassOffset(MostDerivedClassOffset),
995 MostDerivedClassIsVirtual(MostDerivedClassIsVirtual),
996 LayoutClass(LayoutClass), Context(MostDerivedClass->getASTContext()),
997 Overriders(MostDerivedClass, MostDerivedClassOffset, LayoutClass) {
998 assert(!Context.getTargetInfo().getCXXABI().isMicrosoft());
999
1000 LayoutVTable();
1001
1002 if (Context.getLangOpts().DumpVTableLayouts)
1003 dumpLayout(llvm::outs());
1004 }
1005
1006 uint64_t getNumThunks() const {
1007 return Thunks.size();
1008 }
1009
1010 ThunksMapTy::const_iterator thunks_begin() const {
1011 return Thunks.begin();
1012 }
1013
1014 ThunksMapTy::const_iterator thunks_end() const {
1015 return Thunks.end();
1016 }
1017
1018 const VBaseOffsetOffsetsMapTy &getVBaseOffsetOffsets() const {
1019 return VBaseOffsetOffsets;
1020 }
1021
1022 const AddressPointsMapTy &getAddressPoints() const {
1023 return AddressPoints;
1024 }
1025
1026 MethodVTableIndicesTy::const_iterator vtable_indices_begin() const {
1027 return MethodVTableIndices.begin();
1028 }
1029
1030 MethodVTableIndicesTy::const_iterator vtable_indices_end() const {
1031 return MethodVTableIndices.end();
1032 }
1033
1034 ArrayRef<VTableComponent> vtable_components() const { return Components; }
1035
1036 AddressPointsMapTy::const_iterator address_points_begin() const {
1037 return AddressPoints.begin();
1038 }
1039
1040 AddressPointsMapTy::const_iterator address_points_end() const {
1041 return AddressPoints.end();
1042 }
1043
1044 VTableThunksMapTy::const_iterator vtable_thunks_begin() const {
1045 return VTableThunks.begin();
1046 }
1047
1048 VTableThunksMapTy::const_iterator vtable_thunks_end() const {
1049 return VTableThunks.end();
1050 }
1051
1052 /// dumpLayout - Dump the vtable layout.
1053 void dumpLayout(raw_ostream&);
1054 };
1055
1056 void ItaniumVTableBuilder::AddThunk(const CXXMethodDecl *MD,
1057 const ThunkInfo &Thunk) {
1058 assert(!isBuildingConstructorVTable() &&
1059 "Can't add thunks for construction vtable");
1060
1061 SmallVectorImpl<ThunkInfo> &ThunksVector = Thunks[MD];
1062
1063 // Check if we have this thunk already.
1064 if (std::find(ThunksVector.begin(), ThunksVector.end(), Thunk) !=
1065 ThunksVector.end())
1066 return;
1067
1068 ThunksVector.push_back(Thunk);
1069 }
1070
1071 typedef llvm::SmallPtrSet<const CXXMethodDecl *, 8> OverriddenMethodsSetTy;
1072
1073 /// Visit all the methods overridden by the given method recursively,
1074 /// in a depth-first pre-order. The Visitor's visitor method returns a bool
1075 /// indicating whether to continue the recursion for the given overridden
1076 /// method (i.e. returning false stops the iteration).
1077 template <class VisitorTy>
1078 static void
1079 visitAllOverriddenMethods(const CXXMethodDecl *MD, VisitorTy &Visitor) {
1080 assert(MD->isVirtual() && "Method is not virtual!");
1081
1082 for (const CXXMethodDecl *OverriddenMD : MD->overridden_methods()) {
1083 if (!Visitor(OverriddenMD))
1084 continue;
1085 visitAllOverriddenMethods(OverriddenMD, Visitor);
1086 }
1087 }
1088
1089 /// ComputeAllOverriddenMethods - Given a method decl, will return a set of all
1090 /// the overridden methods that the function decl overrides.
1091 static void
1092 ComputeAllOverriddenMethods(const CXXMethodDecl *MD,
1093 OverriddenMethodsSetTy& OverriddenMethods) {
1094 auto OverriddenMethodsCollector = [&](const CXXMethodDecl *MD) {
1095 // Don't recurse on this method if we've already collected it.
1096 return OverriddenMethods.insert(MD).second;
1097 };
1098 visitAllOverriddenMethods(MD, OverriddenMethodsCollector);
1099 }
1100
1101 void ItaniumVTableBuilder::ComputeThisAdjustments() {
1102 // Now go through the method info map and see if any of the methods need
1103 // 'this' pointer adjustments.
1104 for (const auto &MI : MethodInfoMap) {
1105 const CXXMethodDecl *MD = MI.first;
1106 const MethodInfo &MethodInfo = MI.second;
1107
1108 // Ignore adjustments for unused function pointers.
1109 uint64_t VTableIndex = MethodInfo.VTableIndex;
1110 if (Components[VTableIndex].getKind() ==
1111 VTableComponent::CK_UnusedFunctionPointer)
1112 continue;
1113
1114 // Get the final overrider for this method.
1115 FinalOverriders::OverriderInfo Overrider =
1116 Overriders.getOverrider(MD, MethodInfo.BaseOffset);
1117
1118 // Check if we need an adjustment at all.
1119 if (MethodInfo.BaseOffsetInLayoutClass == Overrider.Offset) {
1120 // When a return thunk is needed by a derived class that overrides a
1121 // virtual base, gcc uses a virtual 'this' adjustment as well.
1122 // While the thunk itself might be needed by vtables in subclasses or
1123 // in construction vtables, there doesn't seem to be a reason for using
1124 // the thunk in this vtable. Still, we do so to match gcc.
1125 if (VTableThunks.lookup(VTableIndex).Return.isEmpty())
1126 continue;
1127 }
1128
1129 ThisAdjustment ThisAdjustment =
1130 ComputeThisAdjustment(MD, MethodInfo.BaseOffsetInLayoutClass, Overrider);
1131
1132 if (ThisAdjustment.isEmpty())
1133 continue;
1134
1135 // Add it.
1136 VTableThunks[VTableIndex].This = ThisAdjustment;
1137
1138 if (isa<CXXDestructorDecl>(MD)) {
1139 // Add an adjustment for the deleting destructor as well.
1140 VTableThunks[VTableIndex + 1].This = ThisAdjustment;
1141 }
1142 }
1143
1144 /// Clear the method info map.
1145 MethodInfoMap.clear();
1146
1147 if (isBuildingConstructorVTable()) {
1148 // We don't need to store thunk information for construction vtables.
1149 return;
1150 }
1151
1152 for (const auto &TI : VTableThunks) {
1153 const VTableComponent &Component = Components[TI.first];
1154 const ThunkInfo &Thunk = TI.second;
1155 const CXXMethodDecl *MD;
1156
1157 switch (Component.getKind()) {
1158 default:
1159 llvm_unreachable("Unexpected vtable component kind!");
1160 case VTableComponent::CK_FunctionPointer:
1161 MD = Component.getFunctionDecl();
1162 break;
1163 case VTableComponent::CK_CompleteDtorPointer:
1164 MD = Component.getDestructorDecl();
1165 break;
1166 case VTableComponent::CK_DeletingDtorPointer:
1167 // We've already added the thunk when we saw the complete dtor pointer.
1168 continue;
1169 }
1170
1171 if (MD->getParent() == MostDerivedClass)
1172 AddThunk(MD, Thunk);
1173 }
1174 }
1175
1176 ReturnAdjustment
1177 ItaniumVTableBuilder::ComputeReturnAdjustment(BaseOffset Offset) {
1178 ReturnAdjustment Adjustment;
1179
1180 if (!Offset.isEmpty()) {
1181 if (Offset.VirtualBase) {
1182 // Get the virtual base offset offset.
1183 if (Offset.DerivedClass == MostDerivedClass) {
1184 // We can get the offset offset directly from our map.
1185 Adjustment.Virtual.Itanium.VBaseOffsetOffset =
1186 VBaseOffsetOffsets.lookup(Offset.VirtualBase).getQuantity();
1187 } else {
1188 Adjustment.Virtual.Itanium.VBaseOffsetOffset =
1189 VTables.getVirtualBaseOffsetOffset(Offset.DerivedClass,
1190 Offset.VirtualBase).getQuantity();
1191 }
1192 }
1193
1194 Adjustment.NonVirtual = Offset.NonVirtualOffset.getQuantity();
1195 }
1196
1197 return Adjustment;
1198 }
1199
1200 BaseOffset ItaniumVTableBuilder::ComputeThisAdjustmentBaseOffset(
1201 BaseSubobject Base, BaseSubobject Derived) const {
1202 const CXXRecordDecl *BaseRD = Base.getBase();
1203 const CXXRecordDecl *DerivedRD = Derived.getBase();
1204
1205 CXXBasePaths Paths(/*FindAmbiguities=*/true,
1206 /*RecordPaths=*/true, /*DetectVirtual=*/true);
1207
1208 if (!DerivedRD->isDerivedFrom(BaseRD, Paths))
1209 llvm_unreachable("Class must be derived from the passed in base class!");
1210
1211 // We have to go through all the paths, and see which one leads us to the
1212 // right base subobject.
1213 for (const CXXBasePath &Path : Paths) {
1214 BaseOffset Offset = ComputeBaseOffset(Context, DerivedRD, Path);
1215
1216 CharUnits OffsetToBaseSubobject = Offset.NonVirtualOffset;
1217
1218 if (Offset.VirtualBase) {
1219 // If we have a virtual base class, the non-virtual offset is relative
1220 // to the virtual base class offset.
1221 const ASTRecordLayout &LayoutClassLayout =
1222 Context.getASTRecordLayout(LayoutClass);
1223
1224 /// Get the virtual base offset, relative to the most derived class
1225 /// layout.
1226 OffsetToBaseSubobject +=
1227 LayoutClassLayout.getVBaseClassOffset(Offset.VirtualBase);
1228 } else {
1229 // Otherwise, the non-virtual offset is relative to the derived class
1230 // offset.
1231 OffsetToBaseSubobject += Derived.getBaseOffset();
1232 }
1233
1234 // Check if this path gives us the right base subobject.
1235 if (OffsetToBaseSubobject == Base.getBaseOffset()) {
1236 // Since we're going from the base class _to_ the derived class, we'll
1237 // invert the non-virtual offset here.
1238 Offset.NonVirtualOffset = -Offset.NonVirtualOffset;
1239 return Offset;
1240 }
1241 }
1242
1243 return BaseOffset();
1244 }
1245
1246 ThisAdjustment ItaniumVTableBuilder::ComputeThisAdjustment(
1247 const CXXMethodDecl *MD, CharUnits BaseOffsetInLayoutClass,
1248 FinalOverriders::OverriderInfo Overrider) {
1249 // Ignore adjustments for pure virtual member functions.
1250 if (Overrider.Method->isPure())
1251 return ThisAdjustment();
1252
1253 BaseSubobject OverriddenBaseSubobject(MD->getParent(),
1254 BaseOffsetInLayoutClass);
1255
1256 BaseSubobject OverriderBaseSubobject(Overrider.Method->getParent(),
1257 Overrider.Offset);
1258
1259 // Compute the adjustment offset.
1260 BaseOffset Offset = ComputeThisAdjustmentBaseOffset(OverriddenBaseSubobject,
1261 OverriderBaseSubobject);
1262 if (Offset.isEmpty())
1263 return ThisAdjustment();
1264
1265 ThisAdjustment Adjustment;
1266
1267 if (Offset.VirtualBase) {
1268 // Get the vcall offset map for this virtual base.
1269 VCallOffsetMap &VCallOffsets = VCallOffsetsForVBases[Offset.VirtualBase];
1270
1271 if (VCallOffsets.empty()) {
1272 // We don't have vcall offsets for this virtual base, go ahead and
1273 // build them.
1274 VCallAndVBaseOffsetBuilder Builder(MostDerivedClass, MostDerivedClass,
1275 /*FinalOverriders=*/nullptr,
1276 BaseSubobject(Offset.VirtualBase,
1277 CharUnits::Zero()),
1278 /*BaseIsVirtual=*/true,
1279 /*OffsetInLayoutClass=*/
1280 CharUnits::Zero());
1281
1282 VCallOffsets = Builder.getVCallOffsets();
1283 }
1284
1285 Adjustment.Virtual.Itanium.VCallOffsetOffset =
1286 VCallOffsets.getVCallOffsetOffset(MD).getQuantity();
1287 }
1288
1289 // Set the non-virtual part of the adjustment.
1290 Adjustment.NonVirtual = Offset.NonVirtualOffset.getQuantity();
1291
1292 return Adjustment;
1293 }
1294
1295 void ItaniumVTableBuilder::AddMethod(const CXXMethodDecl *MD,
1296 ReturnAdjustment ReturnAdjustment) {
1297 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1298 assert(ReturnAdjustment.isEmpty() &&
1299 "Destructor can't have return adjustment!");
1300
1301 // Add both the complete destructor and the deleting destructor.
1302 Components.push_back(VTableComponent::MakeCompleteDtor(DD));
1303 Components.push_back(VTableComponent::MakeDeletingDtor(DD));
1304 } else {
1305 // Add the return adjustment if necessary.
1306 if (!ReturnAdjustment.isEmpty())
1307 VTableThunks[Components.size()].Return = ReturnAdjustment;
1308
1309 // Add the function.
1310 Components.push_back(VTableComponent::MakeFunction(MD));
1311 }
1312 }
1313
1314 /// OverridesIndirectMethodInBase - Return whether the given member function
1315 /// overrides any methods in the set of given bases.
1316 /// Unlike OverridesMethodInBase, this checks "overriders of overriders".
1317 /// For example, if we have:
1318 ///
1319 /// struct A { virtual void f(); }
1320 /// struct B : A { virtual void f(); }
1321 /// struct C : B { virtual void f(); }
1322 ///
1323 /// OverridesIndirectMethodInBase will return true if given C::f as the method
1324 /// and { A } as the set of bases.
1325 static bool OverridesIndirectMethodInBases(
1326 const CXXMethodDecl *MD,
1327 ItaniumVTableBuilder::PrimaryBasesSetVectorTy &Bases) {
1328 if (Bases.count(MD->getParent()))
1329 return true;
1330
1331 for (const CXXMethodDecl *OverriddenMD : MD->overridden_methods()) {
1332 // Check "indirect overriders".
1333 if (OverridesIndirectMethodInBases(OverriddenMD, Bases))
1334 return true;
1335 }
1336
1337 return false;
1338 }
1339
1340 bool ItaniumVTableBuilder::IsOverriderUsed(
1341 const CXXMethodDecl *Overrider, CharUnits BaseOffsetInLayoutClass,
1342 const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
1343 CharUnits FirstBaseOffsetInLayoutClass) const {
1344 // If the base and the first base in the primary base chain have the same
1345 // offsets, then this overrider will be used.
1346 if (BaseOffsetInLayoutClass == FirstBaseOffsetInLayoutClass)
1347 return true;
1348
1349 // We know now that Base (or a direct or indirect base of it) is a primary
1350 // base in part of the class hierarchy, but not a primary base in the most
1351 // derived class.
1352
1353 // If the overrider is the first base in the primary base chain, we know
1354 // that the overrider will be used.
1355 if (Overrider->getParent() == FirstBaseInPrimaryBaseChain)
1356 return true;
1357
1358 ItaniumVTableBuilder::PrimaryBasesSetVectorTy PrimaryBases;
1359
1360 const CXXRecordDecl *RD = FirstBaseInPrimaryBaseChain;
1361 PrimaryBases.insert(RD);
1362
1363 // Now traverse the base chain, starting with the first base, until we find
1364 // the base that is no longer a primary base.
1365 while (true) {
1366 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1367 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
1368
1369 if (!PrimaryBase)
1370 break;
1371
1372 if (Layout.isPrimaryBaseVirtual()) {
1373 assert(Layout.getVBaseClassOffset(PrimaryBase).isZero() &&
1374 "Primary base should always be at offset 0!");
1375
1376 const ASTRecordLayout &LayoutClassLayout =
1377 Context.getASTRecordLayout(LayoutClass);
1378
1379 // Now check if this is the primary base that is not a primary base in the
1380 // most derived class.
1381 if (LayoutClassLayout.getVBaseClassOffset(PrimaryBase) !=
1382 FirstBaseOffsetInLayoutClass) {
1383 // We found it, stop walking the chain.
1384 break;
1385 }
1386 } else {
1387 assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
1388 "Primary base should always be at offset 0!");
1389 }
1390
1391 if (!PrimaryBases.insert(PrimaryBase))
1392 llvm_unreachable("Found a duplicate primary base!");
1393
1394 RD = PrimaryBase;
1395 }
1396
1397 // If the final overrider is an override of one of the primary bases,
1398 // then we know that it will be used.
1399 return OverridesIndirectMethodInBases(Overrider, PrimaryBases);
1400 }
1401
1402 typedef llvm::SmallSetVector<const CXXRecordDecl *, 8> BasesSetVectorTy;
1403
1404 /// FindNearestOverriddenMethod - Given a method, returns the overridden method
1405 /// from the nearest base. Returns null if no method was found.
1406 /// The Bases are expected to be sorted in a base-to-derived order.
1407 static const CXXMethodDecl *
1408 FindNearestOverriddenMethod(const CXXMethodDecl *MD,
1409 BasesSetVectorTy &Bases) {
1410 OverriddenMethodsSetTy OverriddenMethods;
1411 ComputeAllOverriddenMethods(MD, OverriddenMethods);
1412
1413 for (const CXXRecordDecl *PrimaryBase :
1414 llvm::make_range(Bases.rbegin(), Bases.rend())) {
1415 // Now check the overridden methods.
1416 for (const CXXMethodDecl *OverriddenMD : OverriddenMethods) {
1417 // We found our overridden method.
1418 if (OverriddenMD->getParent() == PrimaryBase)
1419 return OverriddenMD;
1420 }
1421 }
1422
1423 return nullptr;
1424 }
1425
1426 void ItaniumVTableBuilder::AddMethods(
1427 BaseSubobject Base, CharUnits BaseOffsetInLayoutClass,
1428 const CXXRecordDecl *FirstBaseInPrimaryBaseChain,
1429 CharUnits FirstBaseOffsetInLayoutClass,
1430 PrimaryBasesSetVectorTy &PrimaryBases) {
1431 // Itanium C++ ABI 2.5.2:
1432 // The order of the virtual function pointers in a virtual table is the
1433 // order of declaration of the corresponding member functions in the class.
1434 //
1435 // There is an entry for any virtual function declared in a class,
1436 // whether it is a new function or overrides a base class function,
1437 // unless it overrides a function from the primary base, and conversion
1438 // between their return types does not require an adjustment.
1439
1440 const CXXRecordDecl *RD = Base.getBase();
1441 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1442
1443 if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
1444 CharUnits PrimaryBaseOffset;
1445 CharUnits PrimaryBaseOffsetInLayoutClass;
1446 if (Layout.isPrimaryBaseVirtual()) {
1447 assert(Layout.getVBaseClassOffset(PrimaryBase).isZero() &&
1448 "Primary vbase should have a zero offset!");
1449
1450 const ASTRecordLayout &MostDerivedClassLayout =
1451 Context.getASTRecordLayout(MostDerivedClass);
1452
1453 PrimaryBaseOffset =
1454 MostDerivedClassLayout.getVBaseClassOffset(PrimaryBase);
1455
1456 const ASTRecordLayout &LayoutClassLayout =
1457 Context.getASTRecordLayout(LayoutClass);
1458
1459 PrimaryBaseOffsetInLayoutClass =
1460 LayoutClassLayout.getVBaseClassOffset(PrimaryBase);
1461 } else {
1462 assert(Layout.getBaseClassOffset(PrimaryBase).isZero() &&
1463 "Primary base should have a zero offset!");
1464
1465 PrimaryBaseOffset = Base.getBaseOffset();
1466 PrimaryBaseOffsetInLayoutClass = BaseOffsetInLayoutClass;
1467 }
1468
1469 AddMethods(BaseSubobject(PrimaryBase, PrimaryBaseOffset),
1470 PrimaryBaseOffsetInLayoutClass, FirstBaseInPrimaryBaseChain,
1471 FirstBaseOffsetInLayoutClass, PrimaryBases);
1472
1473 if (!PrimaryBases.insert(PrimaryBase))
1474 llvm_unreachable("Found a duplicate primary base!");
1475 }
1476
1477 const CXXDestructorDecl *ImplicitVirtualDtor = nullptr;
1478
1479 typedef llvm::SmallVector<const CXXMethodDecl *, 8> NewVirtualFunctionsTy;
1480 NewVirtualFunctionsTy NewVirtualFunctions;
1481
1482 // Now go through all virtual member functions and add them.
1483 for (const auto *MD : RD->methods()) {
1484 if (!MD->isVirtual())
1485 continue;
1486 MD = MD->getCanonicalDecl();
1487
1488 // Get the final overrider.
1489 FinalOverriders::OverriderInfo Overrider =
1490 Overriders.getOverrider(MD, Base.getBaseOffset());
1491
1492 // Check if this virtual member function overrides a method in a primary
1493 // base. If this is the case, and the return type doesn't require adjustment
1494 // then we can just use the member function from the primary base.
1495 if (const CXXMethodDecl *OverriddenMD =
1496 FindNearestOverriddenMethod(MD, PrimaryBases)) {
1497 if (ComputeReturnAdjustmentBaseOffset(Context, MD,
1498 OverriddenMD).isEmpty()) {
1499 // Replace the method info of the overridden method with our own
1500 // method.
1501 assert(MethodInfoMap.count(OverriddenMD) &&
1502 "Did not find the overridden method!");
1503 MethodInfo &OverriddenMethodInfo = MethodInfoMap[OverriddenMD];
1504
1505 MethodInfo MethodInfo(Base.getBaseOffset(), BaseOffsetInLayoutClass,
1506 OverriddenMethodInfo.VTableIndex);
1507
1508 assert(!MethodInfoMap.count(MD) &&
1509 "Should not have method info for this method yet!");
1510
1511 MethodInfoMap.insert(std::make_pair(MD, MethodInfo));
1512 MethodInfoMap.erase(OverriddenMD);
1513
1514 // If the overridden method exists in a virtual base class or a direct
1515 // or indirect base class of a virtual base class, we need to emit a
1516 // thunk if we ever have a class hierarchy where the base class is not
1517 // a primary base in the complete object.
1518 if (!isBuildingConstructorVTable() && OverriddenMD != MD) {
1519 // Compute the this adjustment.
1520 ThisAdjustment ThisAdjustment =
1521 ComputeThisAdjustment(OverriddenMD, BaseOffsetInLayoutClass,
1522 Overrider);
1523
1524 if (ThisAdjustment.Virtual.Itanium.VCallOffsetOffset &&
1525 Overrider.Method->getParent() == MostDerivedClass) {
1526
1527 // There's no return adjustment from OverriddenMD and MD,
1528 // but that doesn't mean there isn't one between MD and
1529 // the final overrider.
1530 BaseOffset ReturnAdjustmentOffset =
1531 ComputeReturnAdjustmentBaseOffset(Context, Overrider.Method, MD);
1532 ReturnAdjustment ReturnAdjustment =
1533 ComputeReturnAdjustment(ReturnAdjustmentOffset);
1534
1535 // This is a virtual thunk for the most derived class, add it.
1536 AddThunk(Overrider.Method,
1537 ThunkInfo(ThisAdjustment, ReturnAdjustment));
1538 }
1539 }
1540
1541 continue;
1542 }
1543 }
1544
1545 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1546 if (MD->isImplicit()) {
1547 // Itanium C++ ABI 2.5.2:
1548 // If a class has an implicitly-defined virtual destructor,
1549 // its entries come after the declared virtual function pointers.
1550
1551 assert(!ImplicitVirtualDtor &&
1552 "Did already see an implicit virtual dtor!");
1553 ImplicitVirtualDtor = DD;
1554 continue;
1555 }
1556 }
1557
1558 NewVirtualFunctions.push_back(MD);
1559 }
1560
1561 if (ImplicitVirtualDtor)
1562 NewVirtualFunctions.push_back(ImplicitVirtualDtor);
1563
1564 for (const CXXMethodDecl *MD : NewVirtualFunctions) {
1565 // Get the final overrider.
1566 FinalOverriders::OverriderInfo Overrider =
1567 Overriders.getOverrider(MD, Base.getBaseOffset());
1568
1569 // Insert the method info for this method.
1570 MethodInfo MethodInfo(Base.getBaseOffset(), BaseOffsetInLayoutClass,
1571 Components.size());
1572
1573 assert(!MethodInfoMap.count(MD) &&
1574 "Should not have method info for this method yet!");
1575 MethodInfoMap.insert(std::make_pair(MD, MethodInfo));
1576
1577 // Check if this overrider is going to be used.
1578 const CXXMethodDecl *OverriderMD = Overrider.Method;
1579 if (!IsOverriderUsed(OverriderMD, BaseOffsetInLayoutClass,
1580 FirstBaseInPrimaryBaseChain,
1581 FirstBaseOffsetInLayoutClass)) {
1582 Components.push_back(VTableComponent::MakeUnusedFunction(OverriderMD));
1583 continue;
1584 }
1585
1586 // Check if this overrider needs a return adjustment.
1587 // We don't want to do this for pure virtual member functions.
1588 BaseOffset ReturnAdjustmentOffset;
1589 if (!OverriderMD->isPure()) {
1590 ReturnAdjustmentOffset =
1591 ComputeReturnAdjustmentBaseOffset(Context, OverriderMD, MD);
1592 }
1593
1594 ReturnAdjustment ReturnAdjustment =
1595 ComputeReturnAdjustment(ReturnAdjustmentOffset);
1596
1597 AddMethod(Overrider.Method, ReturnAdjustment);
1598 }
1599 }
1600
1601 void ItaniumVTableBuilder::LayoutVTable() {
1602 LayoutPrimaryAndSecondaryVTables(BaseSubobject(MostDerivedClass,
1603 CharUnits::Zero()),
1604 /*BaseIsMorallyVirtual=*/false,
1605 MostDerivedClassIsVirtual,
1606 MostDerivedClassOffset);
1607
1608 VisitedVirtualBasesSetTy VBases;
1609
1610 // Determine the primary virtual bases.
1611 DeterminePrimaryVirtualBases(MostDerivedClass, MostDerivedClassOffset,
1612 VBases);
1613 VBases.clear();
1614
1615 LayoutVTablesForVirtualBases(MostDerivedClass, VBases);
1616
1617 // -fapple-kext adds an extra entry at end of vtbl.
1618 bool IsAppleKext = Context.getLangOpts().AppleKext;
1619 if (IsAppleKext)
1620 Components.push_back(VTableComponent::MakeVCallOffset(CharUnits::Zero()));
1621 }
1622
1623 void ItaniumVTableBuilder::LayoutPrimaryAndSecondaryVTables(
1624 BaseSubobject Base, bool BaseIsMorallyVirtual,
1625 bool BaseIsVirtualInLayoutClass, CharUnits OffsetInLayoutClass) {
1626 assert(Base.getBase()->isDynamicClass() && "class does not have a vtable!");
1627
1628 unsigned VTableIndex = Components.size();
1629 VTableIndices.push_back(VTableIndex);
1630
1631 // Add vcall and vbase offsets for this vtable.
1632 VCallAndVBaseOffsetBuilder Builder(MostDerivedClass, LayoutClass, &Overriders,
1633 Base, BaseIsVirtualInLayoutClass,
1634 OffsetInLayoutClass);
1635 Components.append(Builder.components_begin(), Builder.components_end());
1636
1637 // Check if we need to add these vcall offsets.
1638 if (BaseIsVirtualInLayoutClass && !Builder.getVCallOffsets().empty()) {
1639 VCallOffsetMap &VCallOffsets = VCallOffsetsForVBases[Base.getBase()];
1640
1641 if (VCallOffsets.empty())
1642 VCallOffsets = Builder.getVCallOffsets();
1643 }
1644
1645 // If we're laying out the most derived class we want to keep track of the
1646 // virtual base class offset offsets.
1647 if (Base.getBase() == MostDerivedClass)
1648 VBaseOffsetOffsets = Builder.getVBaseOffsetOffsets();
1649
1650 // Add the offset to top.
1651 CharUnits OffsetToTop = MostDerivedClassOffset - OffsetInLayoutClass;
1652 Components.push_back(VTableComponent::MakeOffsetToTop(OffsetToTop));
1653
1654 // Next, add the RTTI.
1655 Components.push_back(VTableComponent::MakeRTTI(MostDerivedClass));
1656
1657 uint64_t AddressPoint = Components.size();
1658
1659 // Now go through all virtual member functions and add them.
1660 PrimaryBasesSetVectorTy PrimaryBases;
1661 AddMethods(Base, OffsetInLayoutClass,
1662 Base.getBase(), OffsetInLayoutClass,
1663 PrimaryBases);
1664
1665 const CXXRecordDecl *RD = Base.getBase();
1666 if (RD == MostDerivedClass) {
1667 assert(MethodVTableIndices.empty());
1668 for (const auto &I : MethodInfoMap) {
1669 const CXXMethodDecl *MD = I.first;
1670 const MethodInfo &MI = I.second;
1671 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
1672 MethodVTableIndices[GlobalDecl(DD, Dtor_Complete)]
1673 = MI.VTableIndex - AddressPoint;
1674 MethodVTableIndices[GlobalDecl(DD, Dtor_Deleting)]
1675 = MI.VTableIndex + 1 - AddressPoint;
1676 } else {
1677 MethodVTableIndices[MD] = MI.VTableIndex - AddressPoint;
1678 }
1679 }
1680 }
1681
1682 // Compute 'this' pointer adjustments.
1683 ComputeThisAdjustments();
1684
1685 // Add all address points.
1686 while (true) {
1687 AddressPoints.insert(
1688 std::make_pair(BaseSubobject(RD, OffsetInLayoutClass),
1689 VTableLayout::AddressPointLocation{
1690 unsigned(VTableIndices.size() - 1),
1691 unsigned(AddressPoint - VTableIndex)}));
1692
1693 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1694 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
1695
1696 if (!PrimaryBase)
1697 break;
1698
1699 if (Layout.isPrimaryBaseVirtual()) {
1700 // Check if this virtual primary base is a primary base in the layout
1701 // class. If it's not, we don't want to add it.
1702 const ASTRecordLayout &LayoutClassLayout =
1703 Context.getASTRecordLayout(LayoutClass);
1704
1705 if (LayoutClassLayout.getVBaseClassOffset(PrimaryBase) !=
1706 OffsetInLayoutClass) {
1707 // We don't want to add this class (or any of its primary bases).
1708 break;
1709 }
1710 }
1711
1712 RD = PrimaryBase;
1713 }
1714
1715 // Layout secondary vtables.
1716 LayoutSecondaryVTables(Base, BaseIsMorallyVirtual, OffsetInLayoutClass);
1717 }
1718
1719 void
1720 ItaniumVTableBuilder::LayoutSecondaryVTables(BaseSubobject Base,
1721 bool BaseIsMorallyVirtual,
1722 CharUnits OffsetInLayoutClass) {
1723 // Itanium C++ ABI 2.5.2:
1724 // Following the primary virtual table of a derived class are secondary
1725 // virtual tables for each of its proper base classes, except any primary
1726 // base(s) with which it shares its primary virtual table.
1727
1728 const CXXRecordDecl *RD = Base.getBase();
1729 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1730 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
1731
1732 for (const auto &B : RD->bases()) {
1733 // Ignore virtual bases, we'll emit them later.
1734 if (B.isVirtual())
1735 continue;
1736
1737 const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
1738
1739 // Ignore bases that don't have a vtable.
1740 if (!BaseDecl->isDynamicClass())
1741 continue;
1742
1743 if (isBuildingConstructorVTable()) {
1744 // Itanium C++ ABI 2.6.4:
1745 // Some of the base class subobjects may not need construction virtual
1746 // tables, which will therefore not be present in the construction
1747 // virtual table group, even though the subobject virtual tables are
1748 // present in the main virtual table group for the complete object.
1749 if (!BaseIsMorallyVirtual && !BaseDecl->getNumVBases())
1750 continue;
1751 }
1752
1753 // Get the base offset of this base.
1754 CharUnits RelativeBaseOffset = Layout.getBaseClassOffset(BaseDecl);
1755 CharUnits BaseOffset = Base.getBaseOffset() + RelativeBaseOffset;
1756
1757 CharUnits BaseOffsetInLayoutClass =
1758 OffsetInLayoutClass + RelativeBaseOffset;
1759
1760 // Don't emit a secondary vtable for a primary base. We might however want
1761 // to emit secondary vtables for other bases of this base.
1762 if (BaseDecl == PrimaryBase) {
1763 LayoutSecondaryVTables(BaseSubobject(BaseDecl, BaseOffset),
1764 BaseIsMorallyVirtual, BaseOffsetInLayoutClass);
1765 continue;
1766 }
1767
1768 // Layout the primary vtable (and any secondary vtables) for this base.
1769 LayoutPrimaryAndSecondaryVTables(
1770 BaseSubobject(BaseDecl, BaseOffset),
1771 BaseIsMorallyVirtual,
1772 /*BaseIsVirtualInLayoutClass=*/false,
1773 BaseOffsetInLayoutClass);
1774 }
1775 }
1776
1777 void ItaniumVTableBuilder::DeterminePrimaryVirtualBases(
1778 const CXXRecordDecl *RD, CharUnits OffsetInLayoutClass,
1779 VisitedVirtualBasesSetTy &VBases) {
1780 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1781
1782 // Check if this base has a primary base.
1783 if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
1784
1785 // Check if it's virtual.
1786 if (Layout.isPrimaryBaseVirtual()) {
1787 bool IsPrimaryVirtualBase = true;
1788
1789 if (isBuildingConstructorVTable()) {
1790 // Check if the base is actually a primary base in the class we use for
1791 // layout.
1792 const ASTRecordLayout &LayoutClassLayout =
1793 Context.getASTRecordLayout(LayoutClass);
1794
1795 CharUnits PrimaryBaseOffsetInLayoutClass =
1796 LayoutClassLayout.getVBaseClassOffset(PrimaryBase);
1797
1798 // We know that the base is not a primary base in the layout class if
1799 // the base offsets are different.
1800 if (PrimaryBaseOffsetInLayoutClass != OffsetInLayoutClass)
1801 IsPrimaryVirtualBase = false;
1802 }
1803
1804 if (IsPrimaryVirtualBase)
1805 PrimaryVirtualBases.insert(PrimaryBase);
1806 }
1807 }
1808
1809 // Traverse bases, looking for more primary virtual bases.
1810 for (const auto &B : RD->bases()) {
1811 const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
1812
1813 CharUnits BaseOffsetInLayoutClass;
1814
1815 if (B.isVirtual()) {
1816 if (!VBases.insert(BaseDecl).second)
1817 continue;
1818
1819 const ASTRecordLayout &LayoutClassLayout =
1820 Context.getASTRecordLayout(LayoutClass);
1821
1822 BaseOffsetInLayoutClass =
1823 LayoutClassLayout.getVBaseClassOffset(BaseDecl);
1824 } else {
1825 BaseOffsetInLayoutClass =
1826 OffsetInLayoutClass + Layout.getBaseClassOffset(BaseDecl);
1827 }
1828
1829 DeterminePrimaryVirtualBases(BaseDecl, BaseOffsetInLayoutClass, VBases);
1830 }
1831 }
1832
1833 void ItaniumVTableBuilder::LayoutVTablesForVirtualBases(
1834 const CXXRecordDecl *RD, VisitedVirtualBasesSetTy &VBases) {
1835 // Itanium C++ ABI 2.5.2:
1836 // Then come the virtual base virtual tables, also in inheritance graph
1837 // order, and again excluding primary bases (which share virtual tables with
1838 // the classes for which they are primary).
1839 for (const auto &B : RD->bases()) {
1840 const CXXRecordDecl *BaseDecl = B.getType()->getAsCXXRecordDecl();
1841
1842 // Check if this base needs a vtable. (If it's virtual, not a primary base
1843 // of some other class, and we haven't visited it before).
1844 if (B.isVirtual() && BaseDecl->isDynamicClass() &&
1845 !PrimaryVirtualBases.count(BaseDecl) &&
1846 VBases.insert(BaseDecl).second) {
1847 const ASTRecordLayout &MostDerivedClassLayout =
1848 Context.getASTRecordLayout(MostDerivedClass);
1849 CharUnits BaseOffset =
1850 MostDerivedClassLayout.getVBaseClassOffset(BaseDecl);
1851
1852 const ASTRecordLayout &LayoutClassLayout =
1853 Context.getASTRecordLayout(LayoutClass);
1854 CharUnits BaseOffsetInLayoutClass =
1855 LayoutClassLayout.getVBaseClassOffset(BaseDecl);
1856
1857 LayoutPrimaryAndSecondaryVTables(
1858 BaseSubobject(BaseDecl, BaseOffset),
1859 /*BaseIsMorallyVirtual=*/true,
1860 /*BaseIsVirtualInLayoutClass=*/true,
1861 BaseOffsetInLayoutClass);
1862 }
1863
1864 // We only need to check the base for virtual base vtables if it actually
1865 // has virtual bases.
1866 if (BaseDecl->getNumVBases())
1867 LayoutVTablesForVirtualBases(BaseDecl, VBases);
1868 }
1869 }
1870
1871 /// dumpLayout - Dump the vtable layout.
1872 void ItaniumVTableBuilder::dumpLayout(raw_ostream &Out) {
1873 // FIXME: write more tests that actually use the dumpLayout output to prevent
1874 // ItaniumVTableBuilder regressions.
1875
1876 if (isBuildingConstructorVTable()) {
1877 Out << "Construction vtable for ('";
1878 MostDerivedClass->printQualifiedName(Out);
1879 Out << "', ";
1880 Out << MostDerivedClassOffset.getQuantity() << ") in '";
1881 LayoutClass->printQualifiedName(Out);
1882 } else {
1883 Out << "Vtable for '";
1884 MostDerivedClass->printQualifiedName(Out);
1885 }
1886 Out << "' (" << Components.size() << " entries).\n";
1887
1888 // Iterate through the address points and insert them into a new map where
1889 // they are keyed by the index and not the base object.
1890 // Since an address point can be shared by multiple subobjects, we use an
1891 // STL multimap.
1892 std::multimap<uint64_t, BaseSubobject> AddressPointsByIndex;
1893 for (const auto &AP : AddressPoints) {
1894 const BaseSubobject &Base = AP.first;
1895 uint64_t Index =
1896 VTableIndices[AP.second.VTableIndex] + AP.second.AddressPointIndex;
1897
1898 AddressPointsByIndex.insert(std::make_pair(Index, Base));
1899 }
1900
1901 for (unsigned I = 0, E = Components.size(); I != E; ++I) {
1902 uint64_t Index = I;
1903
1904 Out << llvm::format("%4d | ", I);
1905
1906 const VTableComponent &Component = Components[I];
1907
1908 // Dump the component.
1909 switch (Component.getKind()) {
1910
1911 case VTableComponent::CK_VCallOffset:
1912 Out << "vcall_offset ("
1913 << Component.getVCallOffset().getQuantity()
1914 << ")";
1915 break;
1916
1917 case VTableComponent::CK_VBaseOffset:
1918 Out << "vbase_offset ("
1919 << Component.getVBaseOffset().getQuantity()
1920 << ")";
1921 break;
1922
1923 case VTableComponent::CK_OffsetToTop:
1924 Out << "offset_to_top ("
1925 << Component.getOffsetToTop().getQuantity()
1926 << ")";
1927 break;
1928
1929 case VTableComponent::CK_RTTI:
1930 Component.getRTTIDecl()->printQualifiedName(Out);
1931 Out << " RTTI";
1932 break;
1933
1934 case VTableComponent::CK_FunctionPointer: {
1935 const CXXMethodDecl *MD = Component.getFunctionDecl();
1936
1937 std::string Str =
1938 PredefinedExpr::ComputeName(PredefinedExpr::PrettyFunctionNoVirtual,
1939 MD);
1940 Out << Str;
1941 if (MD->isPure())
1942 Out << " [pure]";
1943
1944 if (MD->isDeleted())
1945 Out << " [deleted]";
1946
1947 ThunkInfo Thunk = VTableThunks.lookup(I);
1948 if (!Thunk.isEmpty()) {
1949 // If this function pointer has a return adjustment, dump it.
1950 if (!Thunk.Return.isEmpty()) {
1951 Out << "\n [return adjustment: ";
1952 Out << Thunk.Return.NonVirtual << " non-virtual";
1953
1954 if (Thunk.Return.Virtual.Itanium.VBaseOffsetOffset) {
1955 Out << ", " << Thunk.Return.Virtual.Itanium.VBaseOffsetOffset;
1956 Out << " vbase offset offset";
1957 }
1958
1959 Out << ']';
1960 }
1961
1962 // If this function pointer has a 'this' pointer adjustment, dump it.
1963 if (!Thunk.This.isEmpty()) {
1964 Out << "\n [this adjustment: ";
1965 Out << Thunk.This.NonVirtual << " non-virtual";
1966
1967 if (Thunk.This.Virtual.Itanium.VCallOffsetOffset) {
1968 Out << ", " << Thunk.This.Virtual.Itanium.VCallOffsetOffset;
1969 Out << " vcall offset offset";
1970 }
1971
1972 Out << ']';
1973 }
1974 }
1975
1976 break;
1977 }
1978
1979 case VTableComponent::CK_CompleteDtorPointer:
1980 case VTableComponent::CK_DeletingDtorPointer: {
1981 bool IsComplete =
1982 Component.getKind() == VTableComponent::CK_CompleteDtorPointer;
1983
1984 const CXXDestructorDecl *DD = Component.getDestructorDecl();
1985
1986 DD->printQualifiedName(Out);
1987 if (IsComplete)
1988 Out << "() [complete]";
1989 else
1990 Out << "() [deleting]";
1991
1992 if (DD->isPure())
1993 Out << " [pure]";
1994
1995 ThunkInfo Thunk = VTableThunks.lookup(I);
1996 if (!Thunk.isEmpty()) {
1997 // If this destructor has a 'this' pointer adjustment, dump it.
1998 if (!Thunk.This.isEmpty()) {
1999 Out << "\n [this adjustment: ";
2000 Out << Thunk.This.NonVirtual << " non-virtual";
2001
2002 if (Thunk.This.Virtual.Itanium.VCallOffsetOffset) {
2003 Out << ", " << Thunk.This.Virtual.Itanium.VCallOffsetOffset;
2004 Out << " vcall offset offset";
2005 }
2006
2007 Out << ']';
2008 }
2009 }
2010
2011 break;
2012 }
2013
2014 case VTableComponent::CK_UnusedFunctionPointer: {
2015 const CXXMethodDecl *MD = Component.getUnusedFunctionDecl();
2016
2017 std::string Str =
2018 PredefinedExpr::ComputeName(PredefinedExpr::PrettyFunctionNoVirtual,
2019 MD);
2020 Out << "[unused] " << Str;
2021 if (MD->isPure())
2022 Out << " [pure]";
2023 }
2024
2025 }
2026
2027 Out << '\n';
2028
2029 // Dump the next address point.
2030 uint64_t NextIndex = Index + 1;
2031 if (AddressPointsByIndex.count(NextIndex)) {
2032 if (AddressPointsByIndex.count(NextIndex) == 1) {
2033 const BaseSubobject &Base =
2034 AddressPointsByIndex.find(NextIndex)->second;
2035
2036 Out << " -- (";
2037 Base.getBase()->printQualifiedName(Out);
2038 Out << ", " << Base.getBaseOffset().getQuantity();
2039 Out << ") vtable address --\n";
2040 } else {
2041 CharUnits BaseOffset =
2042 AddressPointsByIndex.lower_bound(NextIndex)->second.getBaseOffset();
2043
2044 // We store the class names in a set to get a stable order.
2045 std::set<std::string> ClassNames;
2046 for (const auto &I :
2047 llvm::make_range(AddressPointsByIndex.equal_range(NextIndex))) {
2048 assert(I.second.getBaseOffset() == BaseOffset &&
2049 "Invalid base offset!");
2050 const CXXRecordDecl *RD = I.second.getBase();
2051 ClassNames.insert(RD->getQualifiedNameAsString());
2052 }
2053
2054 for (const std::string &Name : ClassNames) {
2055 Out << " -- (" << Name;
2056 Out << ", " << BaseOffset.getQuantity() << ") vtable address --\n";
2057 }
2058 }
2059 }
2060 }
2061
2062 Out << '\n';
2063
2064 if (isBuildingConstructorVTable())
2065 return;
2066
2067 if (MostDerivedClass->getNumVBases()) {
2068 // We store the virtual base class names and their offsets in a map to get
2069 // a stable order.
2070
2071 std::map<std::string, CharUnits> ClassNamesAndOffsets;
2072 for (const auto &I : VBaseOffsetOffsets) {
2073 std::string ClassName = I.first->getQualifiedNameAsString();
2074 CharUnits OffsetOffset = I.second;
2075 ClassNamesAndOffsets.insert(std::make_pair(ClassName, OffsetOffset));
2076 }
2077
2078 Out << "Virtual base offset offsets for '";
2079 MostDerivedClass->printQualifiedName(Out);
2080 Out << "' (";
2081 Out << ClassNamesAndOffsets.size();
2082 Out << (ClassNamesAndOffsets.size() == 1 ? " entry" : " entries") << ").\n";
2083
2084 for (const auto &I : ClassNamesAndOffsets)
2085 Out << " " << I.first << " | " << I.second.getQuantity() << '\n';
2086
2087 Out << "\n";
2088 }
2089
2090 if (!Thunks.empty()) {
2091 // We store the method names in a map to get a stable order.
2092 std::map<std::string, const CXXMethodDecl *> MethodNamesAndDecls;
2093
2094 for (const auto &I : Thunks) {
2095 const CXXMethodDecl *MD = I.first;
2096 std::string MethodName =
2097 PredefinedExpr::ComputeName(PredefinedExpr::PrettyFunctionNoVirtual,
2098 MD);
2099
2100 MethodNamesAndDecls.insert(std::make_pair(MethodName, MD));
2101 }
2102
2103 for (const auto &I : MethodNamesAndDecls) {
2104 const std::string &MethodName = I.first;
2105 const CXXMethodDecl *MD = I.second;
2106
2107 ThunkInfoVectorTy ThunksVector = Thunks[MD];
2108 llvm::sort(ThunksVector, [](const ThunkInfo &LHS, const ThunkInfo &RHS) {
2109 assert(LHS.Method == nullptr && RHS.Method == nullptr);
2110 return std::tie(LHS.This, LHS.Return) < std::tie(RHS.This, RHS.Return);
2111 });
2112
2113 Out << "Thunks for '" << MethodName << "' (" << ThunksVector.size();
2114 Out << (ThunksVector.size() == 1 ? " entry" : " entries") << ").\n";
2115
2116 for (unsigned I = 0, E = ThunksVector.size(); I != E; ++I) {
2117 const ThunkInfo &Thunk = ThunksVector[I];
2118
2119 Out << llvm::format("%4d | ", I);
2120
2121 // If this function pointer has a return pointer adjustment, dump it.
2122 if (!Thunk.Return.isEmpty()) {
2123 Out << "return adjustment: " << Thunk.Return.NonVirtual;
2124 Out << " non-virtual";
2125 if (Thunk.Return.Virtual.Itanium.VBaseOffsetOffset) {
2126 Out << ", " << Thunk.Return.Virtual.Itanium.VBaseOffsetOffset;
2127 Out << " vbase offset offset";
2128 }
2129
2130 if (!Thunk.This.isEmpty())
2131 Out << "\n ";
2132 }
2133
2134 // If this function pointer has a 'this' pointer adjustment, dump it.
2135 if (!Thunk.This.isEmpty()) {
2136 Out << "this adjustment: ";
2137 Out << Thunk.This.NonVirtual << " non-virtual";
2138
2139 if (Thunk.This.Virtual.Itanium.VCallOffsetOffset) {
2140 Out << ", " << Thunk.This.Virtual.Itanium.VCallOffsetOffset;
2141 Out << " vcall offset offset";
2142 }
2143 }
2144
2145 Out << '\n';
2146 }
2147
2148 Out << '\n';
2149 }
2150 }
2151
2152 // Compute the vtable indices for all the member functions.
2153 // Store them in a map keyed by the index so we'll get a sorted table.
2154 std::map<uint64_t, std::string> IndicesMap;
2155
2156 for (const auto *MD : MostDerivedClass->methods()) {
2157 // We only want virtual member functions.
2158 if (!MD->isVirtual())
2159 continue;
2160 MD = MD->getCanonicalDecl();
2161
2162 std::string MethodName =
2163 PredefinedExpr::ComputeName(PredefinedExpr::PrettyFunctionNoVirtual,
2164 MD);
2165
2166 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
2167 GlobalDecl GD(DD, Dtor_Complete);
2168 assert(MethodVTableIndices.count(GD));
2169 uint64_t VTableIndex = MethodVTableIndices[GD];
2170 IndicesMap[VTableIndex] = MethodName + " [complete]";
2171 IndicesMap[VTableIndex + 1] = MethodName + " [deleting]";
2172 } else {
2173 assert(MethodVTableIndices.count(MD));
2174 IndicesMap[MethodVTableIndices[MD]] = MethodName;
2175 }
2176 }
2177
2178 // Print the vtable indices for all the member functions.
2179 if (!IndicesMap.empty()) {
2180 Out << "VTable indices for '";
2181 MostDerivedClass->printQualifiedName(Out);
2182 Out << "' (" << IndicesMap.size() << " entries).\n";
2183
2184 for (const auto &I : IndicesMap) {
2185 uint64_t VTableIndex = I.first;
2186 const std::string &MethodName = I.second;
2187
2188 Out << llvm::format("%4" PRIu64 " | ", VTableIndex) << MethodName
2189 << '\n';
2190 }
2191 }
2192
2193 Out << '\n';
2194 }
2195 }
2196
2197 VTableLayout::VTableLayout(ArrayRef<size_t> VTableIndices,
2198 ArrayRef<VTableComponent> VTableComponents,
2199 ArrayRef<VTableThunkTy> VTableThunks,
2200 const AddressPointsMapTy &AddressPoints)
2201 : VTableComponents(VTableComponents), VTableThunks(VTableThunks),
2202 AddressPoints(AddressPoints) {
2203 if (VTableIndices.size() <= 1)
2204 assert(VTableIndices.size() == 1 && VTableIndices[0] == 0);
2205 else
2206 this->VTableIndices = OwningArrayRef<size_t>(VTableIndices);
2207
2208 llvm::sort(this->VTableThunks, [](const VTableLayout::VTableThunkTy &LHS,
2209 const VTableLayout::VTableThunkTy &RHS) {
2210 assert((LHS.first != RHS.first || LHS.second == RHS.second) &&
2211 "Different thunks should have unique indices!");
2212 return LHS.first < RHS.first;
2213 });
2214 }
2215
2216 VTableLayout::~VTableLayout() { }
2217
2218 ItaniumVTableContext::ItaniumVTableContext(ASTContext &Context)
2219 : VTableContextBase(/*MS=*/false) {}
2220
2221 ItaniumVTableContext::~ItaniumVTableContext() {}
2222
2223 uint64_t ItaniumVTableContext::getMethodVTableIndex(GlobalDecl GD) {
2224 GD = GD.getCanonicalDecl();
2225 MethodVTableIndicesTy::iterator I = MethodVTableIndices.find(GD);
2226 if (I != MethodVTableIndices.end())
2227 return I->second;
2228
2229 const CXXRecordDecl *RD = cast<CXXMethodDecl>(GD.getDecl())->getParent();
2230
2231 computeVTableRelatedInformation(RD);
2232
2233 I = MethodVTableIndices.find(GD);
2234 assert(I != MethodVTableIndices.end() && "Did not find index!");
2235 return I->second;
2236 }
2237
2238 CharUnits
2239 ItaniumVTableContext::getVirtualBaseOffsetOffset(const CXXRecordDecl *RD,
2240 const CXXRecordDecl *VBase) {
2241 ClassPairTy ClassPair(RD, VBase);
2242
2243 VirtualBaseClassOffsetOffsetsMapTy::iterator I =
2244 VirtualBaseClassOffsetOffsets.find(ClassPair);
2245 if (I != VirtualBaseClassOffsetOffsets.end())
2246 return I->second;
2247
2248 VCallAndVBaseOffsetBuilder Builder(RD, RD, /*FinalOverriders=*/nullptr,
2249 BaseSubobject(RD, CharUnits::Zero()),
2250 /*BaseIsVirtual=*/false,
2251 /*OffsetInLayoutClass=*/CharUnits::Zero());
2252
2253 for (const auto &I : Builder.getVBaseOffsetOffsets()) {
2254 // Insert all types.
2255 ClassPairTy ClassPair(RD, I.first);
2256
2257 VirtualBaseClassOffsetOffsets.insert(std::make_pair(ClassPair, I.second));
2258 }
2259
2260 I = VirtualBaseClassOffsetOffsets.find(ClassPair);
2261 assert(I != VirtualBaseClassOffsetOffsets.end() && "Did not find index!");
2262
2263 return I->second;
2264 }
2265
2266 static std::unique_ptr<VTableLayout>
2267 CreateVTableLayout(const ItaniumVTableBuilder &Builder) {
2268 SmallVector<VTableLayout::VTableThunkTy, 1>
2269 VTableThunks(Builder.vtable_thunks_begin(), Builder.vtable_thunks_end());
2270
2271 return llvm::make_unique<VTableLayout>(
2272 Builder.VTableIndices, Builder.vtable_components(), VTableThunks,
2273 Builder.getAddressPoints());
2274 }
2275
2276 void
2277 ItaniumVTableContext::computeVTableRelatedInformation(const CXXRecordDecl *RD) {
2278 std::unique_ptr<const VTableLayout> &Entry = VTableLayouts[RD];
2279
2280 // Check if we've computed this information before.
2281 if (Entry)
2282 return;
2283
2284 ItaniumVTableBuilder Builder(*this, RD, CharUnits::Zero(),
2285 /*MostDerivedClassIsVirtual=*/0, RD);
2286 Entry = CreateVTableLayout(Builder);
2287
2288 MethodVTableIndices.insert(Builder.vtable_indices_begin(),
2289 Builder.vtable_indices_end());
2290
2291 // Add the known thunks.
2292 Thunks.insert(Builder.thunks_begin(), Builder.thunks_end());
2293
2294 // If we don't have the vbase information for this class, insert it.
2295 // getVirtualBaseOffsetOffset will compute it separately without computing
2296 // the rest of the vtable related information.
2297 if (!RD->getNumVBases())
2298 return;
2299
2300 const CXXRecordDecl *VBase =
2301 RD->vbases_begin()->getType()->getAsCXXRecordDecl();
2302
2303 if (VirtualBaseClassOffsetOffsets.count(std::make_pair(RD, VBase)))
2304 return;
2305
2306 for (const auto &I : Builder.getVBaseOffsetOffsets()) {
2307 // Insert all types.
2308 ClassPairTy ClassPair(RD, I.first);
2309
2310 VirtualBaseClassOffsetOffsets.insert(std::make_pair(ClassPair, I.second));
2311 }
2312 }
2313
2314 std::unique_ptr<VTableLayout>
2315 ItaniumVTableContext::createConstructionVTableLayout(
2316 const CXXRecordDecl *MostDerivedClass, CharUnits MostDerivedClassOffset,
2317 bool MostDerivedClassIsVirtual, const CXXRecordDecl *LayoutClass) {
2318 ItaniumVTableBuilder Builder(*this, MostDerivedClass, MostDerivedClassOffset,
2319 MostDerivedClassIsVirtual, LayoutClass);
2320 return CreateVTableLayout(Builder);
2321 }
2322
2323 namespace {
2324
2325 // Vtables in the Microsoft ABI are different from the Itanium ABI.
2326 //
2327 // The main differences are:
2328 // 1. Separate vftable and vbtable.
2329 //
2330 // 2. Each subobject with a vfptr gets its own vftable rather than an address
2331 // point in a single vtable shared between all the subobjects.
2332 // Each vftable is represented by a separate section and virtual calls
2333 // must be done using the vftable which has a slot for the function to be
2334 // called.
2335 //
2336 // 3. Virtual method definitions expect their 'this' parameter to point to the
2337 // first vfptr whose table provides a compatible overridden method. In many
2338 // cases, this permits the original vf-table entry to directly call
2339 // the method instead of passing through a thunk.
2340 // See example before VFTableBuilder::ComputeThisOffset below.
2341 //
2342 // A compatible overridden method is one which does not have a non-trivial
2343 // covariant-return adjustment.
2344 //
2345 // The first vfptr is the one with the lowest offset in the complete-object
2346 // layout of the defining class, and the method definition will subtract
2347 // that constant offset from the parameter value to get the real 'this'
2348 // value. Therefore, if the offset isn't really constant (e.g. if a virtual
2349 // function defined in a virtual base is overridden in a more derived
2350 // virtual base and these bases have a reverse order in the complete
2351 // object), the vf-table may require a this-adjustment thunk.
2352 //
2353 // 4. vftables do not contain new entries for overrides that merely require
2354 // this-adjustment. Together with #3, this keeps vf-tables smaller and
2355 // eliminates the need for this-adjustment thunks in many cases, at the cost
2356 // of often requiring redundant work to adjust the "this" pointer.
2357 //
2358 // 5. Instead of VTT and constructor vtables, vbtables and vtordisps are used.
2359 // Vtordisps are emitted into the class layout if a class has
2360 // a) a user-defined ctor/dtor
2361 // and
2362 // b) a method overriding a method in a virtual base.
2363 //
2364 // To get a better understanding of this code,
2365 // you might want to see examples in test/CodeGenCXX/microsoft-abi-vtables-*.cpp
2366
2367 class VFTableBuilder {
2368 public:
2369 typedef llvm::DenseMap<GlobalDecl, MethodVFTableLocation>
2370 MethodVFTableLocationsTy;
2371
2372 typedef llvm::iterator_range<MethodVFTableLocationsTy::const_iterator>
2373 method_locations_range;
2374
2375 private:
2376 /// VTables - Global vtable information.
2377 MicrosoftVTableContext &VTables;
2378
2379 /// Context - The ASTContext which we will use for layout information.
2380 ASTContext &Context;
2381
2382 /// MostDerivedClass - The most derived class for which we're building this
2383 /// vtable.
2384 const CXXRecordDecl *MostDerivedClass;
2385
2386 const ASTRecordLayout &MostDerivedClassLayout;
2387
2388 const VPtrInfo &WhichVFPtr;
2389
2390 /// FinalOverriders - The final overriders of the most derived class.
2391 const FinalOverriders Overriders;
2392
2393 /// Components - The components of the vftable being built.
2394 SmallVector<VTableComponent, 64> Components;
2395
2396 MethodVFTableLocationsTy MethodVFTableLocations;
2397
2398 /// Does this class have an RTTI component?
2399 bool HasRTTIComponent = false;
2400
2401 /// MethodInfo - Contains information about a method in a vtable.
2402 /// (Used for computing 'this' pointer adjustment thunks.
2403 struct MethodInfo {
2404 /// VBTableIndex - The nonzero index in the vbtable that
2405 /// this method's base has, or zero.
2406 const uint64_t VBTableIndex;
2407
2408 /// VFTableIndex - The index in the vftable that this method has.
2409 const uint64_t VFTableIndex;
2410
2411 /// Shadowed - Indicates if this vftable slot is shadowed by
2412 /// a slot for a covariant-return override. If so, it shouldn't be printed
2413 /// or used for vcalls in the most derived class.
2414 bool Shadowed;
2415
2416 /// UsesExtraSlot - Indicates if this vftable slot was created because
2417 /// any of the overridden slots required a return adjusting thunk.
2418 bool UsesExtraSlot;
2419
2420 MethodInfo(uint64_t VBTableIndex, uint64_t VFTableIndex,
2421 bool UsesExtraSlot = false)
2422 : VBTableIndex(VBTableIndex), VFTableIndex(VFTableIndex),
2423 Shadowed(false), UsesExtraSlot(UsesExtraSlot) {}
2424
2425 MethodInfo()
2426 : VBTableIndex(0), VFTableIndex(0), Shadowed(false),
2427 UsesExtraSlot(false) {}
2428 };
2429
2430 typedef llvm::DenseMap<const CXXMethodDecl *, MethodInfo> MethodInfoMapTy;
2431
2432 /// MethodInfoMap - The information for all methods in the vftable we're
2433 /// currently building.
2434 MethodInfoMapTy MethodInfoMap;
2435
2436 typedef llvm::DenseMap<uint64_t, ThunkInfo> VTableThunksMapTy;
2437
2438 /// VTableThunks - The thunks by vftable index in the vftable currently being
2439 /// built.
2440 VTableThunksMapTy VTableThunks;
2441
2442 typedef SmallVector<ThunkInfo, 1> ThunkInfoVectorTy;
2443 typedef llvm::DenseMap<const CXXMethodDecl *, ThunkInfoVectorTy> ThunksMapTy;
2444
2445 /// Thunks - A map that contains all the thunks needed for all methods in the
2446 /// most derived class for which the vftable is currently being built.
2447 ThunksMapTy Thunks;
2448
2449 /// AddThunk - Add a thunk for the given method.
2450 void AddThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk) {
2451 SmallVector<ThunkInfo, 1> &ThunksVector = Thunks[MD];
2452
2453 // Check if we have this thunk already.
2454 if (std::find(ThunksVector.begin(), ThunksVector.end(), Thunk) !=
2455 ThunksVector.end())
2456 return;
2457
2458 ThunksVector.push_back(Thunk);
2459 }
2460
2461 /// ComputeThisOffset - Returns the 'this' argument offset for the given
2462 /// method, relative to the beginning of the MostDerivedClass.
2463 CharUnits ComputeThisOffset(FinalOverriders::OverriderInfo Overrider);
2464
2465 void CalculateVtordispAdjustment(FinalOverriders::OverriderInfo Overrider,
2466 CharUnits ThisOffset, ThisAdjustment &TA);
2467
2468 /// AddMethod - Add a single virtual member function to the vftable
2469 /// components vector.
2470 void AddMethod(const CXXMethodDecl *MD, ThunkInfo TI) {
2471 if (!TI.isEmpty()) {
2472 VTableThunks[Components.size()] = TI;
2473 AddThunk(MD, TI);
2474 }
2475 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
2476 assert(TI.Return.isEmpty() &&
2477 "Destructor can't have return adjustment!");
2478 Components.push_back(VTableComponent::MakeDeletingDtor(DD));
2479 } else {
2480 Components.push_back(VTableComponent::MakeFunction(MD));
2481 }
2482 }
2483
2484 /// AddMethods - Add the methods of this base subobject and the relevant
2485 /// subbases to the vftable we're currently laying out.
2486 void AddMethods(BaseSubobject Base, unsigned BaseDepth,
2487 const CXXRecordDecl *LastVBase,
2488 BasesSetVectorTy &VisitedBases);
2489
2490 void LayoutVFTable() {
2491 // RTTI data goes before all other entries.
2492 if (HasRTTIComponent)
2493 Components.push_back(VTableComponent::MakeRTTI(MostDerivedClass));
2494
2495 BasesSetVectorTy VisitedBases;
2496 AddMethods(BaseSubobject(MostDerivedClass, CharUnits::Zero()), 0, nullptr,
2497 VisitedBases);
2498 assert((HasRTTIComponent ? Components.size() - 1 : Components.size()) &&
2499 "vftable can't be empty");
2500
2501 assert(MethodVFTableLocations.empty());
2502 for (const auto &I : MethodInfoMap) {
2503 const CXXMethodDecl *MD = I.first;
2504 const MethodInfo &MI = I.second;
2505 assert(MD == MD->getCanonicalDecl());
2506
2507 // Skip the methods that the MostDerivedClass didn't override
2508 // and the entries shadowed by return adjusting thunks.
2509 if (MD->getParent() != MostDerivedClass || MI.Shadowed)
2510 continue;
2511 MethodVFTableLocation Loc(MI.VBTableIndex, WhichVFPtr.getVBaseWithVPtr(),
2512 WhichVFPtr.NonVirtualOffset, MI.VFTableIndex);
2513 if (const CXXDestructorDecl *DD = dyn_cast<CXXDestructorDecl>(MD)) {
2514 MethodVFTableLocations[GlobalDecl(DD, Dtor_Deleting)] = Loc;
2515 } else {
2516 MethodVFTableLocations[MD] = Loc;
2517 }
2518 }
2519 }
2520
2521 public:
2522 VFTableBuilder(MicrosoftVTableContext &VTables,
2523 const CXXRecordDecl *MostDerivedClass, const VPtrInfo &Which)
2524 : VTables(VTables),
2525 Context(MostDerivedClass->getASTContext()),
2526 MostDerivedClass(MostDerivedClass),
2527 MostDerivedClassLayout(Context.getASTRecordLayout(MostDerivedClass)),
2528 WhichVFPtr(Which),
2529 Overriders(MostDerivedClass, CharUnits(), MostDerivedClass) {
2530 // Provide the RTTI component if RTTIData is enabled. If the vftable would
2531 // be available externally, we should not provide the RTTI componenent. It
2532 // is currently impossible to get available externally vftables with either
2533 // dllimport or extern template instantiations, but eventually we may add a
2534 // flag to support additional devirtualization that needs this.
2535 if (Context.getLangOpts().RTTIData)
2536 HasRTTIComponent = true;
2537
2538 LayoutVFTable();
2539
2540 if (Context.getLangOpts().DumpVTableLayouts)
2541 dumpLayout(llvm::outs());
2542 }
2543
2544 uint64_t getNumThunks() const { return Thunks.size(); }
2545
2546 ThunksMapTy::const_iterator thunks_begin() const { return Thunks.begin(); }
2547
2548 ThunksMapTy::const_iterator thunks_end() const { return Thunks.end(); }
2549
2550 method_locations_range vtable_locations() const {
2551 return method_locations_range(MethodVFTableLocations.begin(),
2552 MethodVFTableLocations.end());
2553 }
2554
2555 ArrayRef<VTableComponent> vtable_components() const { return Components; }
2556
2557 VTableThunksMapTy::const_iterator vtable_thunks_begin() const {
2558 return VTableThunks.begin();
2559 }
2560
2561 VTableThunksMapTy::const_iterator vtable_thunks_end() const {
2562 return VTableThunks.end();
2563 }
2564
2565 void dumpLayout(raw_ostream &);
2566 };
2567
2568 } // end namespace
2569
2570 // Let's study one class hierarchy as an example:
2571 // struct A {
2572 // virtual void f();
2573 // int x;
2574 // };
2575 //
2576 // struct B : virtual A {
2577 // virtual void f();
2578 // };
2579 //
2580 // Record layouts:
2581 // struct A:
2582 // 0 | (A vftable pointer)
2583 // 4 | int x
2584 //
2585 // struct B:
2586 // 0 | (B vbtable pointer)
2587 // 4 | struct A (virtual base)
2588 // 4 | (A vftable pointer)
2589 // 8 | int x
2590 //
2591 // Let's assume we have a pointer to the A part of an object of dynamic type B:
2592 // B b;
2593 // A *a = (A*)&b;
2594 // a->f();
2595 //
2596 // In this hierarchy, f() belongs to the vftable of A, so B::f() expects
2597 // "this" parameter to point at the A subobject, which is B+4.
2598 // In the B::f() prologue, it adjusts "this" back to B by subtracting 4,
2599 // performed as a *static* adjustment.
2600 //
2601 // Interesting thing happens when we alter the relative placement of A and B
2602 // subobjects in a class:
2603 // struct C : virtual B { };
2604 //
2605 // C c;
2606 // A *a = (A*)&c;
2607 // a->f();
2608 //
2609 // Respective record layout is:
2610 // 0 | (C vbtable pointer)
2611 // 4 | struct A (virtual base)
2612 // 4 | (A vftable pointer)
2613 // 8 | int x
2614 // 12 | struct B (virtual base)
2615 // 12 | (B vbtable pointer)
2616 //
2617 // The final overrider of f() in class C is still B::f(), so B+4 should be
2618 // passed as "this" to that code. However, "a" points at B-8, so the respective
2619 // vftable entry should hold a thunk that adds 12 to the "this" argument before
2620 // performing a tail call to B::f().
2621 //
2622 // With this example in mind, we can now calculate the 'this' argument offset
2623 // for the given method, relative to the beginning of the MostDerivedClass.
2624 CharUnits
2625 VFTableBuilder::ComputeThisOffset(FinalOverriders::OverriderInfo Overrider) {
2626 BasesSetVectorTy Bases;
2627
2628 {
2629 // Find the set of least derived bases that define the given method.
2630 OverriddenMethodsSetTy VisitedOverriddenMethods;
2631 auto InitialOverriddenDefinitionCollector = [&](
2632 const CXXMethodDecl *OverriddenMD) {
2633 if (OverriddenMD->size_overridden_methods() == 0)
2634 Bases.insert(OverriddenMD->getParent());
2635 // Don't recurse on this method if we've already collected it.
2636 return VisitedOverriddenMethods.insert(OverriddenMD).second;
2637 };
2638 visitAllOverriddenMethods(Overrider.Method,
2639 InitialOverriddenDefinitionCollector);
2640 }
2641
2642 // If there are no overrides then 'this' is located
2643 // in the base that defines the method.
2644 if (Bases.size() == 0)
2645 return Overrider.Offset;
2646
2647 CXXBasePaths Paths;
2648 Overrider.Method->getParent()->lookupInBases(
2649 [&Bases](const CXXBaseSpecifier *Specifier, CXXBasePath &) {
2650 return Bases.count(Specifier->getType()->getAsCXXRecordDecl());
2651 },
2652 Paths);
2653
2654 // This will hold the smallest this offset among overridees of MD.
2655 // This implies that an offset of a non-virtual base will dominate an offset
2656 // of a virtual base to potentially reduce the number of thunks required
2657 // in the derived classes that inherit this method.
2658 CharUnits Ret;
2659 bool First = true;
2660
2661 const ASTRecordLayout &OverriderRDLayout =
2662 Context.getASTRecordLayout(Overrider.Method->getParent());
2663 for (const CXXBasePath &Path : Paths) {
2664 CharUnits ThisOffset = Overrider.Offset;
2665 CharUnits LastVBaseOffset;
2666
2667 // For each path from the overrider to the parents of the overridden
2668 // methods, traverse the path, calculating the this offset in the most
2669 // derived class.
2670 for (const CXXBasePathElement &Element : Path) {
2671 QualType CurTy = Element.Base->getType();
2672 const CXXRecordDecl *PrevRD = Element.Class,
2673 *CurRD = CurTy->getAsCXXRecordDecl();
2674 const ASTRecordLayout &Layout = Context.getASTRecordLayout(PrevRD);
2675
2676 if (Element.Base->isVirtual()) {
2677 // The interesting things begin when you have virtual inheritance.
2678 // The final overrider will use a static adjustment equal to the offset
2679 // of the vbase in the final overrider class.
2680 // For example, if the final overrider is in a vbase B of the most
2681 // derived class and it overrides a method of the B's own vbase A,
2682 // it uses A* as "this". In its prologue, it can cast A* to B* with
2683 // a static offset. This offset is used regardless of the actual
2684 // offset of A from B in the most derived class, requiring an
2685 // this-adjusting thunk in the vftable if A and B are laid out
2686 // differently in the most derived class.
2687 LastVBaseOffset = ThisOffset =
2688 Overrider.Offset + OverriderRDLayout.getVBaseClassOffset(CurRD);
2689 } else {
2690 ThisOffset += Layout.getBaseClassOffset(CurRD);
2691 }
2692 }
2693
2694 if (isa<CXXDestructorDecl>(Overrider.Method)) {
2695 if (LastVBaseOffset.isZero()) {
2696 // If a "Base" class has at least one non-virtual base with a virtual
2697 // destructor, the "Base" virtual destructor will take the address
2698 // of the "Base" subobject as the "this" argument.
2699 ThisOffset = Overrider.Offset;
2700 } else {
2701 // A virtual destructor of a virtual base takes the address of the
2702 // virtual base subobject as the "this" argument.
2703 ThisOffset = LastVBaseOffset;
2704 }
2705 }
2706
2707 if (Ret > ThisOffset || First) {
2708 First = false;
2709 Ret = ThisOffset;
2710 }
2711 }
2712
2713 assert(!First && "Method not found in the given subobject?");
2714 return Ret;
2715 }
2716
2717 // Things are getting even more complex when the "this" adjustment has to
2718 // use a dynamic offset instead of a static one, or even two dynamic offsets.
2719 // This is sometimes required when a virtual call happens in the middle of
2720 // a non-most-derived class construction or destruction.
2721 //
2722 // Let's take a look at the following example:
2723 // struct A {
2724 // virtual void f();
2725 // };
2726 //
2727 // void foo(A *a) { a->f(); } // Knows nothing about siblings of A.
2728 //
2729 // struct B : virtual A {
2730 // virtual void f();
2731 // B() {
2732 // foo(this);
2733 // }
2734 // };
2735 //
2736 // struct C : virtual B {
2737 // virtual void f();
2738 // };
2739 //
2740 // Record layouts for these classes are:
2741 // struct A
2742 // 0 | (A vftable pointer)
2743 //
2744 // struct B
2745 // 0 | (B vbtable pointer)
2746 // 4 | (vtordisp for vbase A)
2747 // 8 | struct A (virtual base)
2748 // 8 | (A vftable pointer)
2749 //
2750 // struct C
2751 // 0 | (C vbtable pointer)
2752 // 4 | (vtordisp for vbase A)
2753 // 8 | struct A (virtual base) // A precedes B!
2754 // 8 | (A vftable pointer)
2755 // 12 | struct B (virtual base)
2756 // 12 | (B vbtable pointer)
2757 //
2758 // When one creates an object of type C, the C constructor:
2759 // - initializes all the vbptrs, then
2760 // - calls the A subobject constructor
2761 // (initializes A's vfptr with an address of A vftable), then
2762 // - calls the B subobject constructor
2763 // (initializes A's vfptr with an address of B vftable and vtordisp for A),
2764 // that in turn calls foo(), then
2765 // - initializes A's vfptr with an address of C vftable and zeroes out the
2766 // vtordisp
2767 // FIXME: if a structor knows it belongs to MDC, why doesn't it use a vftable
2768 // without vtordisp thunks?
2769 // FIXME: how are vtordisp handled in the presence of nooverride/final?
2770 //
2771 // When foo() is called, an object with a layout of class C has a vftable
2772 // referencing B::f() that assumes a B layout, so the "this" adjustments are
2773 // incorrect, unless an extra adjustment is done. This adjustment is called
2774 // "vtordisp adjustment". Vtordisp basically holds the difference between the
2775 // actual location of a vbase in the layout class and the location assumed by
2776 // the vftable of the class being constructed/destructed. Vtordisp is only
2777 // needed if "this" escapes a
2778 // structor (or we can't prove otherwise).
2779 // [i.e. vtordisp is a dynamic adjustment for a static adjustment, which is an
2780 // estimation of a dynamic adjustment]
2781 //
2782 // foo() gets a pointer to the A vbase and doesn't know anything about B or C,
2783 // so it just passes that pointer as "this" in a virtual call.
2784 // If there was no vtordisp, that would just dispatch to B::f().
2785 // However, B::f() assumes B+8 is passed as "this",
2786 // yet the pointer foo() passes along is B-4 (i.e. C+8).
2787 // An extra adjustment is needed, so we emit a thunk into the B vftable.
2788 // This vtordisp thunk subtracts the value of vtordisp
2789 // from the "this" argument (-12) before making a tailcall to B::f().
2790 //
2791 // Let's consider an even more complex example:
2792 // struct D : virtual B, virtual C {
2793 // D() {
2794 // foo(this);
2795 // }
2796 // };
2797 //
2798 // struct D
2799 // 0 | (D vbtable pointer)
2800 // 4 | (vtordisp for vbase A)
2801 // 8 | struct A (virtual base) // A precedes both B and C!
2802 // 8 | (A vftable pointer)
2803 // 12 | struct B (virtual base) // B precedes C!
2804 // 12 | (B vbtable pointer)
2805 // 16 | struct C (virtual base)
2806 // 16 | (C vbtable pointer)
2807 //
2808 // When D::D() calls foo(), we find ourselves in a thunk that should tailcall
2809 // to C::f(), which assumes C+8 as its "this" parameter. This time, foo()
2810 // passes along A, which is C-8. The A vtordisp holds
2811 // "D.vbptr[index_of_A] - offset_of_A_in_D"
2812 // and we statically know offset_of_A_in_D, so can get a pointer to D.
2813 // When we know it, we can make an extra vbtable lookup to locate the C vbase
2814 // and one extra static adjustment to calculate the expected value of C+8.
2815 void VFTableBuilder::CalculateVtordispAdjustment(
2816 FinalOverriders::OverriderInfo Overrider, CharUnits ThisOffset,
2817 ThisAdjustment &TA) {
2818 const ASTRecordLayout::VBaseOffsetsMapTy &VBaseMap =
2819 MostDerivedClassLayout.getVBaseOffsetsMap();
2820 const ASTRecordLayout::VBaseOffsetsMapTy::const_iterator &VBaseMapEntry =
2821 VBaseMap.find(WhichVFPtr.getVBaseWithVPtr());
2822 assert(VBaseMapEntry != VBaseMap.end());
2823
2824 // If there's no vtordisp or the final overrider is defined in the same vbase
2825 // as the initial declaration, we don't need any vtordisp adjustment.
2826 if (!VBaseMapEntry->second.hasVtorDisp() ||
2827 Overrider.VirtualBase == WhichVFPtr.getVBaseWithVPtr())
2828 return;
2829
2830 // OK, now we know we need to use a vtordisp thunk.
2831 // The implicit vtordisp field is located right before the vbase.
2832 CharUnits OffsetOfVBaseWithVFPtr = VBaseMapEntry->second.VBaseOffset;
2833 TA.Virtual.Microsoft.VtordispOffset =
2834 (OffsetOfVBaseWithVFPtr - WhichVFPtr.FullOffsetInMDC).getQuantity() - 4;
2835
2836 // A simple vtordisp thunk will suffice if the final overrider is defined
2837 // in either the most derived class or its non-virtual base.
2838 if (Overrider.Method->getParent() == MostDerivedClass ||
2839 !Overrider.VirtualBase)
2840 return;
2841
2842 // Otherwise, we need to do use the dynamic offset of the final overrider
2843 // in order to get "this" adjustment right.
2844 TA.Virtual.Microsoft.VBPtrOffset =
2845 (OffsetOfVBaseWithVFPtr + WhichVFPtr.NonVirtualOffset -
2846 MostDerivedClassLayout.getVBPtrOffset()).getQuantity();
2847 TA.Virtual.Microsoft.VBOffsetOffset =
2848 Context.getTypeSizeInChars(Context.IntTy).getQuantity() *
2849 VTables.getVBTableIndex(MostDerivedClass, Overrider.VirtualBase);
2850
2851 TA.NonVirtual = (ThisOffset - Overrider.Offset).getQuantity();
2852 }
2853
2854 static void GroupNewVirtualOverloads(
2855 const CXXRecordDecl *RD,
2856 SmallVector<const CXXMethodDecl *, 10> &VirtualMethods) {
2857 // Put the virtual methods into VirtualMethods in the proper order:
2858 // 1) Group overloads by declaration name. New groups are added to the
2859 // vftable in the order of their first declarations in this class
2860 // (including overrides, non-virtual methods and any other named decl that
2861 // might be nested within the class).
2862 // 2) In each group, new overloads appear in the reverse order of declaration.
2863 typedef SmallVector<const CXXMethodDecl *, 1> MethodGroup;
2864 SmallVector<MethodGroup, 10> Groups;
2865 typedef llvm::DenseMap<DeclarationName, unsigned> VisitedGroupIndicesTy;
2866 VisitedGroupIndicesTy VisitedGroupIndices;
2867 for (const auto *D : RD->decls()) {
2868 const auto *ND = dyn_cast<NamedDecl>(D);
2869 if (!ND)
2870 continue;
2871 VisitedGroupIndicesTy::iterator J;
2872 bool Inserted;
2873 std::tie(J, Inserted) = VisitedGroupIndices.insert(
2874 std::make_pair(ND->getDeclName(), Groups.size()));
2875 if (Inserted)
2876 Groups.push_back(MethodGroup());
2877 if (const auto *MD = dyn_cast<CXXMethodDecl>(ND))
2878 if (MD->isVirtual())
2879 Groups[J->second].push_back(MD->getCanonicalDecl());
2880 }
2881
2882 for (const MethodGroup &Group : Groups)
2883 VirtualMethods.append(Group.rbegin(), Group.rend());
2884 }
2885
2886 static bool isDirectVBase(const CXXRecordDecl *Base, const CXXRecordDecl *RD) {
2887 for (const auto &B : RD->bases()) {
2888 if (B.isVirtual() && B.getType()->getAsCXXRecordDecl() == Base)
2889 return true;
2890 }
2891 return false;
2892 }
2893
2894 void VFTableBuilder::AddMethods(BaseSubobject Base, unsigned BaseDepth,
2895 const CXXRecordDecl *LastVBase,
2896 BasesSetVectorTy &VisitedBases) {
2897 const CXXRecordDecl *RD = Base.getBase();
2898 if (!RD->isPolymorphic())
2899 return;
2900
2901 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
2902
2903 // See if this class expands a vftable of the base we look at, which is either
2904 // the one defined by the vfptr base path or the primary base of the current
2905 // class.
2906 const CXXRecordDecl *NextBase = nullptr, *NextLastVBase = LastVBase;
2907 CharUnits NextBaseOffset;
2908 if (BaseDepth < WhichVFPtr.PathToIntroducingObject.size()) {
2909 NextBase = WhichVFPtr.PathToIntroducingObject[BaseDepth];
2910 if (isDirectVBase(NextBase, RD)) {
2911 NextLastVBase = NextBase;
2912 NextBaseOffset = MostDerivedClassLayout.getVBaseClassOffset(NextBase);
2913 } else {
2914 NextBaseOffset =
2915 Base.getBaseOffset() + Layout.getBaseClassOffset(NextBase);
2916 }
2917 } else if (const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase()) {
2918 assert(!Layout.isPrimaryBaseVirtual() &&
2919 "No primary virtual bases in this ABI");
2920 NextBase = PrimaryBase;
2921 NextBaseOffset = Base.getBaseOffset();
2922 }
2923
2924 if (NextBase) {
2925 AddMethods(BaseSubobject(NextBase, NextBaseOffset), BaseDepth + 1,
2926 NextLastVBase, VisitedBases);
2927 if (!VisitedBases.insert(NextBase))
2928 llvm_unreachable("Found a duplicate primary base!");
2929 }
2930
2931 SmallVector<const CXXMethodDecl*, 10> VirtualMethods;
2932 // Put virtual methods in the proper order.
2933 GroupNewVirtualOverloads(RD, VirtualMethods);
2934
2935 // Now go through all virtual member functions and add them to the current
2936 // vftable. This is done by
2937 // - replacing overridden methods in their existing slots, as long as they
2938 // don't require return adjustment; calculating This adjustment if needed.
2939 // - adding new slots for methods of the current base not present in any
2940 // sub-bases;
2941 // - adding new slots for methods that require Return adjustment.
2942 // We keep track of the methods visited in the sub-bases in MethodInfoMap.
2943 for (const CXXMethodDecl *MD : VirtualMethods) {
2944 FinalOverriders::OverriderInfo FinalOverrider =
2945 Overriders.getOverrider(MD, Base.getBaseOffset());
2946 const CXXMethodDecl *FinalOverriderMD = FinalOverrider.Method;
2947 const CXXMethodDecl *OverriddenMD =
2948 FindNearestOverriddenMethod(MD, VisitedBases);
2949
2950 ThisAdjustment ThisAdjustmentOffset;
2951 bool ReturnAdjustingThunk = false, ForceReturnAdjustmentMangling = false;
2952 CharUnits ThisOffset = ComputeThisOffset(FinalOverrider);
2953 ThisAdjustmentOffset.NonVirtual =
2954 (ThisOffset - WhichVFPtr.FullOffsetInMDC).getQuantity();
2955 if ((OverriddenMD || FinalOverriderMD != MD) &&
2956 WhichVFPtr.getVBaseWithVPtr())
2957 CalculateVtordispAdjustment(FinalOverrider, ThisOffset,
2958 ThisAdjustmentOffset);
2959
2960 unsigned VBIndex =
2961 LastVBase ? VTables.getVBTableIndex(MostDerivedClass, LastVBase) : 0;
2962
2963 if (OverriddenMD) {
2964 // If MD overrides anything in this vftable, we need to update the
2965 // entries.
2966 MethodInfoMapTy::iterator OverriddenMDIterator =
2967 MethodInfoMap.find(OverriddenMD);
2968
2969 // If the overridden method went to a different vftable, skip it.
2970 if (OverriddenMDIterator == MethodInfoMap.end())
2971 continue;
2972
2973 MethodInfo &OverriddenMethodInfo = OverriddenMDIterator->second;
2974
2975 VBIndex = OverriddenMethodInfo.VBTableIndex;
2976
2977 // Let's check if the overrider requires any return adjustments.
2978 // We must create a new slot if the MD's return type is not trivially
2979 // convertible to the OverriddenMD's one.
2980 // Once a chain of method overrides adds a return adjusting vftable slot,
2981 // all subsequent overrides will also use an extra method slot.
2982 ReturnAdjustingThunk = !ComputeReturnAdjustmentBaseOffset(
2983 Context, MD, OverriddenMD).isEmpty() ||
2984 OverriddenMethodInfo.UsesExtraSlot;
2985
2986 if (!ReturnAdjustingThunk) {
2987 // No return adjustment needed - just replace the overridden method info
2988 // with the current info.
2989 MethodInfo MI(VBIndex, OverriddenMethodInfo.VFTableIndex);
2990 MethodInfoMap.erase(OverriddenMDIterator);
2991
2992 assert(!MethodInfoMap.count(MD) &&
2993 "Should not have method info for this method yet!");
2994 MethodInfoMap.insert(std::make_pair(MD, MI));
2995 continue;
2996 }
2997
2998 // In case we need a return adjustment, we'll add a new slot for
2999 // the overrider. Mark the overridden method as shadowed by the new slot.
3000 OverriddenMethodInfo.Shadowed = true;
3001
3002 // Force a special name mangling for a return-adjusting thunk
3003 // unless the method is the final overrider without this adjustment.
3004 ForceReturnAdjustmentMangling =
3005 !(MD == FinalOverriderMD && ThisAdjustmentOffset.isEmpty());
3006 } else if (Base.getBaseOffset() != WhichVFPtr.FullOffsetInMDC ||
3007 MD->size_overridden_methods()) {
3008 // Skip methods that don't belong to the vftable of the current class,
3009 // e.g. each method that wasn't seen in any of the visited sub-bases
3010 // but overrides multiple methods of other sub-bases.
3011 continue;
3012 }
3013
3014 // If we got here, MD is a method not seen in any of the sub-bases or
3015 // it requires return adjustment. Insert the method info for this method.
3016 MethodInfo MI(VBIndex,
3017 HasRTTIComponent ? Components.size() - 1 : Components.size(),
3018 ReturnAdjustingThunk);
3019
3020 assert(!MethodInfoMap.count(MD) &&
3021 "Should not have method info for this method yet!");
3022 MethodInfoMap.insert(std::make_pair(MD, MI));
3023
3024 // Check if this overrider needs a return adjustment.
3025 // We don't want to do this for pure virtual member functions.
3026 BaseOffset ReturnAdjustmentOffset;
3027 ReturnAdjustment ReturnAdjustment;
3028 if (!FinalOverriderMD->isPure()) {
3029 ReturnAdjustmentOffset =
3030 ComputeReturnAdjustmentBaseOffset(Context, FinalOverriderMD, MD);
3031 }
3032 if (!ReturnAdjustmentOffset.isEmpty()) {
3033 ForceReturnAdjustmentMangling = true;
3034 ReturnAdjustment.NonVirtual =
3035 ReturnAdjustmentOffset.NonVirtualOffset.getQuantity();
3036 if (ReturnAdjustmentOffset.VirtualBase) {
3037 const ASTRecordLayout &DerivedLayout =
3038 Context.getASTRecordLayout(ReturnAdjustmentOffset.DerivedClass);
3039 ReturnAdjustment.Virtual.Microsoft.VBPtrOffset =
3040 DerivedLayout.getVBPtrOffset().getQuantity();
3041 ReturnAdjustment.Virtual.Microsoft.VBIndex =
3042 VTables.getVBTableIndex(ReturnAdjustmentOffset.DerivedClass,
3043 ReturnAdjustmentOffset.VirtualBase);
3044 }
3045 }
3046
3047 AddMethod(FinalOverriderMD,
3048 ThunkInfo(ThisAdjustmentOffset, ReturnAdjustment,
3049 ForceReturnAdjustmentMangling ? MD : nullptr));
3050 }
3051 }
3052
3053 static void PrintBasePath(const VPtrInfo::BasePath &Path, raw_ostream &Out) {
3054 for (const CXXRecordDecl *Elem :
3055 llvm::make_range(Path.rbegin(), Path.rend())) {
3056 Out << "'";
3057 Elem->printQualifiedName(Out);
3058 Out << "' in ";
3059 }
3060 }
3061
3062 static void dumpMicrosoftThunkAdjustment(const ThunkInfo &TI, raw_ostream &Out,
3063 bool ContinueFirstLine) {
3064 const ReturnAdjustment &R = TI.Return;
3065 bool Multiline = false;
3066 const char *LinePrefix = "\n ";
3067 if (!R.isEmpty() || TI.Method) {
3068 if (!ContinueFirstLine)
3069 Out << LinePrefix;
3070 Out << "[return adjustment (to type '"
3071 << TI.Method->getReturnType().getCanonicalType().getAsString()
3072 << "'): ";
3073 if (R.Virtual.Microsoft.VBPtrOffset)
3074 Out << "vbptr at offset " << R.Virtual.Microsoft.VBPtrOffset << ", ";
3075 if (R.Virtual.Microsoft.VBIndex)
3076 Out << "vbase #" << R.Virtual.Microsoft.VBIndex << ", ";
3077 Out << R.NonVirtual << " non-virtual]";
3078 Multiline = true;
3079 }
3080
3081 const ThisAdjustment &T = TI.This;
3082 if (!T.isEmpty()) {
3083 if (Multiline || !ContinueFirstLine)
3084 Out << LinePrefix;
3085 Out << "[this adjustment: ";
3086 if (!TI.This.Virtual.isEmpty()) {
3087 assert(T.Virtual.Microsoft.VtordispOffset < 0);
3088 Out << "vtordisp at " << T.Virtual.Microsoft.VtordispOffset << ", ";
3089 if (T.Virtual.Microsoft.VBPtrOffset) {
3090 Out << "vbptr at " << T.Virtual.Microsoft.VBPtrOffset
3091 << " to the left,";
3092 assert(T.Virtual.Microsoft.VBOffsetOffset > 0);
3093 Out << LinePrefix << " vboffset at "
3094 << T.Virtual.Microsoft.VBOffsetOffset << " in the vbtable, ";
3095 }
3096 }
3097 Out << T.NonVirtual << " non-virtual]";
3098 }
3099 }
3100
3101 void VFTableBuilder::dumpLayout(raw_ostream &Out) {
3102 Out << "VFTable for ";
3103 PrintBasePath(WhichVFPtr.PathToIntroducingObject, Out);
3104 Out << "'";
3105 MostDerivedClass->printQualifiedName(Out);
3106 Out << "' (" << Components.size()
3107 << (Components.size() == 1 ? " entry" : " entries") << ").\n";
3108
3109 for (unsigned I = 0, E = Components.size(); I != E; ++I) {
3110 Out << llvm::format("%4d | ", I);
3111
3112 const VTableComponent &Component = Components[I];
3113
3114 // Dump the component.
3115 switch (Component.getKind()) {
3116 case VTableComponent::CK_RTTI:
3117 Component.getRTTIDecl()->printQualifiedName(Out);
3118 Out << " RTTI";
3119 break;
3120
3121 case VTableComponent::CK_FunctionPointer: {
3122 const CXXMethodDecl *MD = Component.getFunctionDecl();
3123
3124 // FIXME: Figure out how to print the real thunk type, since they can
3125 // differ in the return type.
3126 std::string Str = PredefinedExpr::ComputeName(
3127 PredefinedExpr::PrettyFunctionNoVirtual, MD);
3128 Out << Str;
3129 if (MD->isPure())
3130 Out << " [pure]";
3131
3132 if (MD->isDeleted())
3133 Out << " [deleted]";
3134
3135 ThunkInfo Thunk = VTableThunks.lookup(I);
3136 if (!Thunk.isEmpty())
3137 dumpMicrosoftThunkAdjustment(Thunk, Out, /*ContinueFirstLine=*/false);
3138
3139 break;
3140 }
3141
3142 case VTableComponent::CK_DeletingDtorPointer: {
3143 const CXXDestructorDecl *DD = Component.getDestructorDecl();
3144
3145 DD->printQualifiedName(Out);
3146 Out << "() [scalar deleting]";
3147
3148 if (DD->isPure())
3149 Out << " [pure]";
3150
3151 ThunkInfo Thunk = VTableThunks.lookup(I);
3152 if (!Thunk.isEmpty()) {
3153 assert(Thunk.Return.isEmpty() &&
3154 "No return adjustment needed for destructors!");
3155 dumpMicrosoftThunkAdjustment(Thunk, Out, /*ContinueFirstLine=*/false);
3156 }
3157
3158 break;
3159 }
3160
3161 default:
3162 DiagnosticsEngine &Diags = Context.getDiagnostics();
3163 unsigned DiagID = Diags.getCustomDiagID(
3164 DiagnosticsEngine::Error,
3165 "Unexpected vftable component type %0 for component number %1");
3166 Diags.Report(MostDerivedClass->getLocation(), DiagID)
3167 << I << Component.getKind();
3168 }
3169
3170 Out << '\n';
3171 }
3172
3173 Out << '\n';
3174
3175 if (!Thunks.empty()) {
3176 // We store the method names in a map to get a stable order.
3177 std::map<std::string, const CXXMethodDecl *> MethodNamesAndDecls;
3178
3179 for (const auto &I : Thunks) {
3180 const CXXMethodDecl *MD = I.first;
3181 std::string MethodName = PredefinedExpr::ComputeName(
3182 PredefinedExpr::PrettyFunctionNoVirtual, MD);
3183
3184 MethodNamesAndDecls.insert(std::make_pair(MethodName, MD));
3185 }
3186
3187 for (const auto &MethodNameAndDecl : MethodNamesAndDecls) {
3188 const std::string &MethodName = MethodNameAndDecl.first;
3189 const CXXMethodDecl *MD = MethodNameAndDecl.second;
3190
3191 ThunkInfoVectorTy ThunksVector = Thunks[MD];
3192 std::stable_sort(ThunksVector.begin(), ThunksVector.end(),
3193 [](const ThunkInfo &LHS, const ThunkInfo &RHS) {
3194 // Keep different thunks with the same adjustments in the order they
3195 // were put into the vector.
3196 return std::tie(LHS.This, LHS.Return) < std::tie(RHS.This, RHS.Return);
3197 });
3198
3199 Out << "Thunks for '" << MethodName << "' (" << ThunksVector.size();
3200 Out << (ThunksVector.size() == 1 ? " entry" : " entries") << ").\n";
3201
3202 for (unsigned I = 0, E = ThunksVector.size(); I != E; ++I) {
3203 const ThunkInfo &Thunk = ThunksVector[I];
3204
3205 Out << llvm::format("%4d | ", I);
3206 dumpMicrosoftThunkAdjustment(Thunk, Out, /*ContinueFirstLine=*/true);
3207 Out << '\n';
3208 }
3209
3210 Out << '\n';
3211 }
3212 }
3213
3214 Out.flush();
3215 }
3216
3217 static bool setsIntersect(const llvm::SmallPtrSet<const CXXRecordDecl *, 4> &A,
3218 ArrayRef<const CXXRecordDecl *> B) {
3219 for (const CXXRecordDecl *Decl : B) {
3220 if (A.count(Decl))
3221 return true;
3222 }
3223 return false;
3224 }
3225
3226 static bool rebucketPaths(VPtrInfoVector &Paths);
3227
3228 /// Produces MSVC-compatible vbtable data. The symbols produced by this
3229 /// algorithm match those produced by MSVC 2012 and newer, which is different
3230 /// from MSVC 2010.
3231 ///
3232 /// MSVC 2012 appears to minimize the vbtable names using the following
3233 /// algorithm. First, walk the class hierarchy in the usual order, depth first,
3234 /// left to right, to find all of the subobjects which contain a vbptr field.
3235 /// Visiting each class node yields a list of inheritance paths to vbptrs. Each
3236 /// record with a vbptr creates an initially empty path.
3237 ///
3238 /// To combine paths from child nodes, the paths are compared to check for
3239 /// ambiguity. Paths are "ambiguous" if multiple paths have the same set of
3240 /// components in the same order. Each group of ambiguous paths is extended by
3241 /// appending the class of the base from which it came. If the current class
3242 /// node produced an ambiguous path, its path is extended with the current class.
3243 /// After extending paths, MSVC again checks for ambiguity, and extends any
3244 /// ambiguous path which wasn't already extended. Because each node yields an
3245 /// unambiguous set of paths, MSVC doesn't need to extend any path more than once
3246 /// to produce an unambiguous set of paths.
3247 ///
3248 /// TODO: Presumably vftables use the same algorithm.
3249 void MicrosoftVTableContext::computeVTablePaths(bool ForVBTables,
3250 const CXXRecordDecl *RD,
3251 VPtrInfoVector &Paths) {
3252 assert(Paths.empty());
3253 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3254
3255 // Base case: this subobject has its own vptr.
3256 if (ForVBTables ? Layout.hasOwnVBPtr() : Layout.hasOwnVFPtr())
3257 Paths.push_back(llvm::make_unique<VPtrInfo>(RD));
3258
3259 // Recursive case: get all the vbtables from our bases and remove anything
3260 // that shares a virtual base.
3261 llvm::SmallPtrSet<const CXXRecordDecl*, 4> VBasesSeen;
3262 for (const auto &B : RD->bases()) {
3263 const CXXRecordDecl *Base = B.getType()->getAsCXXRecordDecl();
3264 if (B.isVirtual() && VBasesSeen.count(Base))
3265 continue;
3266
3267 if (!Base->isDynamicClass())
3268 continue;
3269
3270 const VPtrInfoVector &BasePaths =
3271 ForVBTables ? enumerateVBTables(Base) : getVFPtrOffsets(Base);
3272
3273 for (const std::unique_ptr<VPtrInfo> &BaseInfo : BasePaths) {
3274 // Don't include the path if it goes through a virtual base that we've
3275 // already included.
3276 if (setsIntersect(VBasesSeen, BaseInfo->ContainingVBases))
3277 continue;
3278
3279 // Copy the path and adjust it as necessary.
3280 auto P = llvm::make_unique<VPtrInfo>(*BaseInfo);
3281
3282 // We mangle Base into the path if the path would've been ambiguous and it
3283 // wasn't already extended with Base.
3284 if (P->MangledPath.empty() || P->MangledPath.back() != Base)
3285 P->NextBaseToMangle = Base;
3286
3287 // Keep track of which vtable the derived class is going to extend with
3288 // new methods or bases. We append to either the vftable of our primary
3289 // base, or the first non-virtual base that has a vbtable.
3290 if (P->ObjectWithVPtr == Base &&
3291 Base == (ForVBTables ? Layout.getBaseSharingVBPtr()
3292 : Layout.getPrimaryBase()))
3293 P->ObjectWithVPtr = RD;
3294
3295 // Keep track of the full adjustment from the MDC to this vtable. The
3296 // adjustment is captured by an optional vbase and a non-virtual offset.
3297 if (B.isVirtual())
3298 P->ContainingVBases.push_back(Base);
3299 else if (P->ContainingVBases.empty())
3300 P->NonVirtualOffset += Layout.getBaseClassOffset(Base);
3301
3302 // Update the full offset in the MDC.
3303 P->FullOffsetInMDC = P->NonVirtualOffset;
3304 if (const CXXRecordDecl *VB = P->getVBaseWithVPtr())
3305 P->FullOffsetInMDC += Layout.getVBaseClassOffset(VB);
3306
3307 Paths.push_back(std::move(P));
3308 }
3309
3310 if (B.isVirtual())
3311 VBasesSeen.insert(Base);
3312
3313 // After visiting any direct base, we've transitively visited all of its
3314 // morally virtual bases.
3315 for (const auto &VB : Base->vbases())
3316 VBasesSeen.insert(VB.getType()->getAsCXXRecordDecl());
3317 }
3318
3319 // Sort the paths into buckets, and if any of them are ambiguous, extend all
3320 // paths in ambiguous buckets.
3321 bool Changed = true;
3322 while (Changed)
3323 Changed = rebucketPaths(Paths);
3324 }
3325
3326 static bool extendPath(VPtrInfo &P) {
3327 if (P.NextBaseToMangle) {
3328 P.MangledPath.push_back(P.NextBaseToMangle);
3329 P.NextBaseToMangle = nullptr;// Prevent the path from being extended twice.
3330 return true;
3331 }
3332 return false;
3333 }
3334
3335 static bool rebucketPaths(VPtrInfoVector &Paths) {
3336 // What we're essentially doing here is bucketing together ambiguous paths.
3337 // Any bucket with more than one path in it gets extended by NextBase, which
3338 // is usually the direct base of the inherited the vbptr. This code uses a
3339 // sorted vector to implement a multiset to form the buckets. Note that the
3340 // ordering is based on pointers, but it doesn't change our output order. The
3341 // current algorithm is designed to match MSVC 2012's names.
3342 llvm::SmallVector<std::reference_wrapper<VPtrInfo>, 2> PathsSorted;
3343 PathsSorted.reserve(Paths.size());
3344 for (auto& P : Paths)
3345 PathsSorted.push_back(*P);
3346 llvm::sort(PathsSorted, [](const VPtrInfo &LHS, const VPtrInfo &RHS) {
3347 return LHS.MangledPath < RHS.MangledPath;
3348 });
3349 bool Changed = false;
3350 for (size_t I = 0, E = PathsSorted.size(); I != E;) {
3351 // Scan forward to find the end of the bucket.
3352 size_t BucketStart = I;
3353 do {
3354 ++I;
3355 } while (I != E &&
3356 PathsSorted[BucketStart].get().MangledPath ==
3357 PathsSorted[I].get().MangledPath);
3358
3359 // If this bucket has multiple paths, extend them all.
3360 if (I - BucketStart > 1) {
3361 for (size_t II = BucketStart; II != I; ++II)
3362 Changed |= extendPath(PathsSorted[II]);
3363 assert(Changed && "no paths were extended to fix ambiguity");
3364 }
3365 }
3366 return Changed;
3367 }
3368
3369 MicrosoftVTableContext::~MicrosoftVTableContext() {}
3370
3371 namespace {
3372 typedef llvm::SetVector<BaseSubobject, std::vector<BaseSubobject>,
3373 llvm::DenseSet<BaseSubobject>> FullPathTy;
3374 }
3375
3376 // This recursive function finds all paths from a subobject centered at
3377 // (RD, Offset) to the subobject located at IntroducingObject.
3378 static void findPathsToSubobject(ASTContext &Context,
3379 const ASTRecordLayout &MostDerivedLayout,
3380 const CXXRecordDecl *RD, CharUnits Offset,
3381 BaseSubobject IntroducingObject,
3382 FullPathTy &FullPath,
3383 std::list<FullPathTy> &Paths) {
3384 if (BaseSubobject(RD, Offset) == IntroducingObject) {
3385 Paths.push_back(FullPath);
3386 return;
3387 }
3388
3389 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3390
3391 for (const CXXBaseSpecifier &BS : RD->bases()) {
3392 const CXXRecordDecl *Base = BS.getType()->getAsCXXRecordDecl();
3393 CharUnits NewOffset = BS.isVirtual()
3394 ? MostDerivedLayout.getVBaseClassOffset(Base)
3395 : Offset + Layout.getBaseClassOffset(Base);
3396 FullPath.insert(BaseSubobject(Base, NewOffset));
3397 findPathsToSubobject(Context, MostDerivedLayout, Base, NewOffset,
3398 IntroducingObject, FullPath, Paths);
3399 FullPath.pop_back();
3400 }
3401 }
3402
3403 // Return the paths which are not subsets of other paths.
3404 static void removeRedundantPaths(std::list<FullPathTy> &FullPaths) {
3405 FullPaths.remove_if([&](const FullPathTy &SpecificPath) {
3406 for (const FullPathTy &OtherPath : FullPaths) {
3407 if (&SpecificPath == &OtherPath)
3408 continue;
3409 if (llvm::all_of(SpecificPath, [&](const BaseSubobject &BSO) {
3410 return OtherPath.count(BSO) != 0;
3411 })) {
3412 return true;
3413 }
3414 }
3415 return false;
3416 });
3417 }
3418
3419 static CharUnits getOffsetOfFullPath(ASTContext &Context,
3420 const CXXRecordDecl *RD,
3421 const FullPathTy &FullPath) {
3422 const ASTRecordLayout &MostDerivedLayout =
3423 Context.getASTRecordLayout(RD);
3424 CharUnits Offset = CharUnits::fromQuantity(-1);
3425 for (const BaseSubobject &BSO : FullPath) {
3426 const CXXRecordDecl *Base = BSO.getBase();
3427 // The first entry in the path is always the most derived record, skip it.
3428 if (Base == RD) {
3429 assert(Offset.getQuantity() == -1);
3430 Offset = CharUnits::Zero();
3431 continue;
3432 }
3433 assert(Offset.getQuantity() != -1);
3434 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3435 // While we know which base has to be traversed, we don't know if that base
3436 // was a virtual base.
3437 const CXXBaseSpecifier *BaseBS = std::find_if(
3438 RD->bases_begin(), RD->bases_end(), [&](const CXXBaseSpecifier &BS) {
3439 return BS.getType()->getAsCXXRecordDecl() == Base;
3440 });
3441 Offset = BaseBS->isVirtual() ? MostDerivedLayout.getVBaseClassOffset(Base)
3442 : Offset + Layout.getBaseClassOffset(Base);
3443 RD = Base;
3444 }
3445 return Offset;
3446 }
3447
3448 // We want to select the path which introduces the most covariant overrides. If
3449 // two paths introduce overrides which the other path doesn't contain, issue a
3450 // diagnostic.
3451 static const FullPathTy *selectBestPath(ASTContext &Context,
3452 const CXXRecordDecl *RD,
3453 const VPtrInfo &Info,
3454 std::list<FullPathTy> &FullPaths) {
3455 // Handle some easy cases first.
3456 if (FullPaths.empty())
3457 return nullptr;
3458 if (FullPaths.size() == 1)
3459 return &FullPaths.front();
3460
3461 const FullPathTy *BestPath = nullptr;
3462 typedef std::set<const CXXMethodDecl *> OverriderSetTy;
3463 OverriderSetTy LastOverrides;
3464 for (const FullPathTy &SpecificPath : FullPaths) {
3465 assert(!SpecificPath.empty());
3466 OverriderSetTy CurrentOverrides;
3467 const CXXRecordDecl *TopLevelRD = SpecificPath.begin()->getBase();
3468 // Find the distance from the start of the path to the subobject with the
3469 // VPtr.
3470 CharUnits BaseOffset =
3471 getOffsetOfFullPath(Context, TopLevelRD, SpecificPath);
3472 FinalOverriders Overriders(TopLevelRD, CharUnits::Zero(), TopLevelRD);
3473 for (const CXXMethodDecl *MD : Info.IntroducingObject->methods()) {
3474 if (!MD->isVirtual())
3475 continue;
3476 FinalOverriders::OverriderInfo OI =
3477 Overriders.getOverrider(MD->getCanonicalDecl(), BaseOffset);
3478 const CXXMethodDecl *OverridingMethod = OI.Method;
3479 // Only overriders which have a return adjustment introduce problematic
3480 // thunks.
3481 if (ComputeReturnAdjustmentBaseOffset(Context, OverridingMethod, MD)
3482 .isEmpty())
3483 continue;
3484 // It's possible that the overrider isn't in this path. If so, skip it
3485 // because this path didn't introduce it.
3486 const CXXRecordDecl *OverridingParent = OverridingMethod->getParent();
3487 if (llvm::none_of(SpecificPath, [&](const BaseSubobject &BSO) {
3488 return BSO.getBase() == OverridingParent;
3489 }))
3490 continue;
3491 CurrentOverrides.insert(OverridingMethod);
3492 }
3493 OverriderSetTy NewOverrides =
3494 llvm::set_difference(CurrentOverrides, LastOverrides);
3495 if (NewOverrides.empty())
3496 continue;
3497 OverriderSetTy MissingOverrides =
3498 llvm::set_difference(LastOverrides, CurrentOverrides);
3499 if (MissingOverrides.empty()) {
3500 // This path is a strict improvement over the last path, let's use it.
3501 BestPath = &SpecificPath;
3502 std::swap(CurrentOverrides, LastOverrides);
3503 } else {
3504 // This path introduces an overrider with a conflicting covariant thunk.
3505 DiagnosticsEngine &Diags = Context.getDiagnostics();
3506 const CXXMethodDecl *CovariantMD = *NewOverrides.begin();
3507 const CXXMethodDecl *ConflictMD = *MissingOverrides.begin();
3508 Diags.Report(RD->getLocation(), diag::err_vftable_ambiguous_component)
3509 << RD;
3510 Diags.Report(CovariantMD->getLocation(), diag::note_covariant_thunk)
3511 << CovariantMD;
3512 Diags.Report(ConflictMD->getLocation(), diag::note_covariant_thunk)
3513 << ConflictMD;
3514 }
3515 }
3516 // Go with the path that introduced the most covariant overrides. If there is
3517 // no such path, pick the first path.
3518 return BestPath ? BestPath : &FullPaths.front();
3519 }
3520
3521 static void computeFullPathsForVFTables(ASTContext &Context,
3522 const CXXRecordDecl *RD,
3523 VPtrInfoVector &Paths) {
3524 const ASTRecordLayout &MostDerivedLayout = Context.getASTRecordLayout(RD);
3525 FullPathTy FullPath;
3526 std::list<FullPathTy> FullPaths;
3527 for (const std::unique_ptr<VPtrInfo>& Info : Paths) {
3528 findPathsToSubobject(
3529 Context, MostDerivedLayout, RD, CharUnits::Zero(),
3530 BaseSubobject(Info->IntroducingObject, Info->FullOffsetInMDC), FullPath,
3531 FullPaths);
3532 FullPath.clear();
3533 removeRedundantPaths(FullPaths);
3534 Info->PathToIntroducingObject.clear();
3535 if (const FullPathTy *BestPath =
3536 selectBestPath(Context, RD, *Info, FullPaths))
3537 for (const BaseSubobject &BSO : *BestPath)
3538 Info->PathToIntroducingObject.push_back(BSO.getBase());
3539 FullPaths.clear();
3540 }
3541 }
3542
3543 static bool vfptrIsEarlierInMDC(const ASTRecordLayout &Layout,
3544 const MethodVFTableLocation &LHS,
3545 const MethodVFTableLocation &RHS) {
3546 CharUnits L = LHS.VFPtrOffset;
3547 CharUnits R = RHS.VFPtrOffset;
3548 if (LHS.VBase)
3549 L += Layout.getVBaseClassOffset(LHS.VBase);
3550 if (RHS.VBase)
3551 R += Layout.getVBaseClassOffset(RHS.VBase);
3552 return L < R;
3553 }
3554
3555 void MicrosoftVTableContext::computeVTableRelatedInformation(
3556 const CXXRecordDecl *RD) {
3557 assert(RD->isDynamicClass());
3558
3559 // Check if we've computed this information before.
3560 if (VFPtrLocations.count(RD))
3561 return;
3562
3563 const VTableLayout::AddressPointsMapTy EmptyAddressPointsMap;
3564
3565 {
3566 auto VFPtrs = llvm::make_unique<VPtrInfoVector>();
3567 computeVTablePaths(/*ForVBTables=*/false, RD, *VFPtrs);
3568 computeFullPathsForVFTables(Context, RD, *VFPtrs);
3569 VFPtrLocations[RD] = std::move(VFPtrs);
3570 }
3571
3572 MethodVFTableLocationsTy NewMethodLocations;
3573 for (const std::unique_ptr<VPtrInfo> &VFPtr : *VFPtrLocations[RD]) {
3574 VFTableBuilder Builder(*this, RD, *VFPtr);
3575
3576 VFTableIdTy id(RD, VFPtr->FullOffsetInMDC);
3577 assert(VFTableLayouts.count(id) == 0);
3578 SmallVector<VTableLayout::VTableThunkTy, 1> VTableThunks(
3579 Builder.vtable_thunks_begin(), Builder.vtable_thunks_end());
3580 VFTableLayouts[id] = llvm::make_unique<VTableLayout>(
3581 ArrayRef<size_t>{0}, Builder.vtable_components(), VTableThunks,
3582 EmptyAddressPointsMap);
3583 Thunks.insert(Builder.thunks_begin(), Builder.thunks_end());
3584
3585 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3586 for (const auto &Loc : Builder.vtable_locations()) {
3587 auto Insert = NewMethodLocations.insert(Loc);
3588 if (!Insert.second) {
3589 const MethodVFTableLocation &NewLoc = Loc.second;
3590 MethodVFTableLocation &OldLoc = Insert.first->second;
3591 if (vfptrIsEarlierInMDC(Layout, NewLoc, OldLoc))
3592 OldLoc = NewLoc;
3593 }
3594 }
3595 }
3596
3597 MethodVFTableLocations.insert(NewMethodLocations.begin(),
3598 NewMethodLocations.end());
3599 if (Context.getLangOpts().DumpVTableLayouts)
3600 dumpMethodLocations(RD, NewMethodLocations, llvm::outs());
3601 }
3602
3603 void MicrosoftVTableContext::dumpMethodLocations(
3604 const CXXRecordDecl *RD, const MethodVFTableLocationsTy &NewMethods,
3605 raw_ostream &Out) {
3606 // Compute the vtable indices for all the member functions.
3607 // Store them in a map keyed by the location so we'll get a sorted table.
3608 std::map<MethodVFTableLocation, std::string> IndicesMap;
3609 bool HasNonzeroOffset = false;
3610
3611 for (const auto &I : NewMethods) {
3612 const CXXMethodDecl *MD = cast<const CXXMethodDecl>(I.first.getDecl());
3613 assert(MD->isVirtual());
3614
3615 std::string MethodName = PredefinedExpr::ComputeName(
3616 PredefinedExpr::PrettyFunctionNoVirtual, MD);
3617
3618 if (isa<CXXDestructorDecl>(MD)) {
3619 IndicesMap[I.second] = MethodName + " [scalar deleting]";
3620 } else {
3621 IndicesMap[I.second] = MethodName;
3622 }
3623
3624 if (!I.second.VFPtrOffset.isZero() || I.second.VBTableIndex != 0)
3625 HasNonzeroOffset = true;
3626 }
3627
3628 // Print the vtable indices for all the member functions.
3629 if (!IndicesMap.empty()) {
3630 Out << "VFTable indices for ";
3631 Out << "'";
3632 RD->printQualifiedName(Out);
3633 Out << "' (" << IndicesMap.size()
3634 << (IndicesMap.size() == 1 ? " entry" : " entries") << ").\n";
3635
3636 CharUnits LastVFPtrOffset = CharUnits::fromQuantity(-1);
3637 uint64_t LastVBIndex = 0;
3638 for (const auto &I : IndicesMap) {
3639 CharUnits VFPtrOffset = I.first.VFPtrOffset;
3640 uint64_t VBIndex = I.first.VBTableIndex;
3641 if (HasNonzeroOffset &&
3642 (VFPtrOffset != LastVFPtrOffset || VBIndex != LastVBIndex)) {
3643 assert(VBIndex > LastVBIndex || VFPtrOffset > LastVFPtrOffset);
3644 Out << " -- accessible via ";
3645 if (VBIndex)
3646 Out << "vbtable index " << VBIndex << ", ";
3647 Out << "vfptr at offset " << VFPtrOffset.getQuantity() << " --\n";
3648 LastVFPtrOffset = VFPtrOffset;
3649 LastVBIndex = VBIndex;
3650 }
3651
3652 uint64_t VTableIndex = I.first.Index;
3653 const std::string &MethodName = I.second;
3654 Out << llvm::format("%4" PRIu64 " | ", VTableIndex) << MethodName << '\n';
3655 }
3656 Out << '\n';
3657 }
3658
3659 Out.flush();
3660 }
3661
3662 const VirtualBaseInfo &MicrosoftVTableContext::computeVBTableRelatedInformation(
3663 const CXXRecordDecl *RD) {
3664 VirtualBaseInfo *VBI;
3665
3666 {
3667 // Get or create a VBI for RD. Don't hold a reference to the DenseMap cell,
3668 // as it may be modified and rehashed under us.
3669 std::unique_ptr<VirtualBaseInfo> &Entry = VBaseInfo[RD];
3670 if (Entry)
3671 return *Entry;
3672 Entry = llvm::make_unique<VirtualBaseInfo>();
3673 VBI = Entry.get();
3674 }
3675
3676 computeVTablePaths(/*ForVBTables=*/true, RD, VBI->VBPtrPaths);
3677
3678 // First, see if the Derived class shared the vbptr with a non-virtual base.
3679 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
3680 if (const CXXRecordDecl *VBPtrBase = Layout.getBaseSharingVBPtr()) {
3681 // If the Derived class shares the vbptr with a non-virtual base, the shared
3682 // virtual bases come first so that the layout is the same.
3683 const VirtualBaseInfo &BaseInfo =
3684 computeVBTableRelatedInformation(VBPtrBase);
3685 VBI->VBTableIndices.insert(BaseInfo.VBTableIndices.begin(),
3686 BaseInfo.VBTableIndices.end());
3687 }
3688
3689 // New vbases are added to the end of the vbtable.
3690 // Skip the self entry and vbases visited in the non-virtual base, if any.
3691 unsigned VBTableIndex = 1 + VBI->VBTableIndices.size();
3692 for (const auto &VB : RD->vbases()) {
3693 const CXXRecordDecl *CurVBase = VB.getType()->getAsCXXRecordDecl();
3694 if (!VBI->VBTableIndices.count(CurVBase))
3695 VBI->VBTableIndices[CurVBase] = VBTableIndex++;
3696 }
3697
3698 return *VBI;
3699 }
3700
3701 unsigned MicrosoftVTableContext::getVBTableIndex(const CXXRecordDecl *Derived,
3702 const CXXRecordDecl *VBase) {
3703 const VirtualBaseInfo &VBInfo = computeVBTableRelatedInformation(Derived);
3704 assert(VBInfo.VBTableIndices.count(VBase));
3705 return VBInfo.VBTableIndices.find(VBase)->second;
3706 }
3707
3708 const VPtrInfoVector &
3709 MicrosoftVTableContext::enumerateVBTables(const CXXRecordDecl *RD) {
3710 return computeVBTableRelatedInformation(RD).VBPtrPaths;
3711 }
3712
3713 const VPtrInfoVector &
3714 MicrosoftVTableContext::getVFPtrOffsets(const CXXRecordDecl *RD) {
3715 computeVTableRelatedInformation(RD);
3716
3717 assert(VFPtrLocations.count(RD) && "Couldn't find vfptr locations");
3718 return *VFPtrLocations[RD];
3719 }
3720
3721 const VTableLayout &
3722 MicrosoftVTableContext::getVFTableLayout(const CXXRecordDecl *RD,
3723 CharUnits VFPtrOffset) {
3724 computeVTableRelatedInformation(RD);
3725
3726 VFTableIdTy id(RD, VFPtrOffset);
3727 assert(VFTableLayouts.count(id) && "Couldn't find a VFTable at this offset");
3728 return *VFTableLayouts[id];
3729 }
3730
3731 MethodVFTableLocation
3732 MicrosoftVTableContext::getMethodVFTableLocation(GlobalDecl GD) {
3733 assert(cast<CXXMethodDecl>(GD.getDecl())->isVirtual() &&
3734 "Only use this method for virtual methods or dtors");
3735 if (isa<CXXDestructorDecl>(GD.getDecl()))
3736 assert(GD.getDtorType() == Dtor_Deleting);
3737
3738 GD = GD.getCanonicalDecl();
3739
3740 MethodVFTableLocationsTy::iterator I = MethodVFTableLocations.find(GD);
3741 if (I != MethodVFTableLocations.end())
3742 return I->second;
3743
3744 const CXXRecordDecl *RD = cast<CXXMethodDecl>(GD.getDecl())->getParent();
3745
3746 computeVTableRelatedInformation(RD);
3747
3748 I = MethodVFTableLocations.find(GD);
3749 assert(I != MethodVFTableLocations.end() && "Did not find index!");
3750 return I->second;
3751 }
ASTContext.h
Defines the clang::ASTContext interface.
clang::if
if(T->getSizeExpr()) TRY_TO(TraverseStmt(T -> getSizeExpr()))
clang::PointerType
PointerType - C99 6.7.5.1 - Pointer Declarators.
Definition: Type.h:2537
clang::ASTRecordLayout::isPrimaryBaseVirtual
bool isPrimaryBaseVirtual() const
isPrimaryBaseVirtual - Get whether the primary base for this record is virtual or not...
Definition: RecordLayout.h:226
clang::QualType
A (possibly-)qualified type.
Definition: Type.h:638
clang::CXXRecordDecl::bases
base_class_range bases()
Definition: DeclCXX.h:823
clang::ReturnAdjustment::VirtualAdjustment::VBPtrOffset
uint32_t VBPtrOffset
The offset (in bytes) of the vbptr, relative to the beginning of the derived class.
Definition: ABI.h:61
clang::ThisAdjustment::isEmpty
bool isEmpty() const
Definition: ABI.h:155
clang::GlobalDecl::getDtorType
CXXDtorType getDtorType() const
Definition: GlobalDecl.h:76
clang::ItaniumVTableContext::ItaniumVTableContext
ItaniumVTableContext(ASTContext &Context)
Definition: VTableBuilder.cpp:2218
clang::VTableComponent::MakeRTTI
static VTableComponent MakeRTTI(const CXXRecordDecl *RD)
Definition: VTableBuilder.h:67
clang::VTableComponent::getFunctionDecl
const CXXMethodDecl * getFunctionDecl() const
Definition: VTableBuilder.h:124
clang::ASTContext::getASTRecordLayout
const ASTRecordLayout & getASTRecordLayout(const RecordDecl *D) const
Get or compute information about the layout of the specified record (struct/union/class) D...
Definition: RecordLayoutBuilder.cpp:2966
clang::FunctionType
FunctionType - C99 6.7.5.3 - Function Declarators.
Definition: Type.h:3355
clang::ASTRecordLayout::getBaseClassOffset
CharUnits getBaseClassOffset(const CXXRecordDecl *Base) const
getBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:233
clang::CXXRecordDecl::getNumVBases
unsigned getNumVBases() const
Retrieves the number of virtual base classes of this class.
Definition: DeclCXX.h:838
Base
clang::VirtualBaseInfo::VBPtrPaths
VPtrInfoVector VBPtrPaths
Information on all virtual base tables used when this record is the most derived class.
Definition: VTableBuilder.h:472
clang::ReturnAdjustment::isEmpty
bool isEmpty() const
Definition: ABI.h:87
clang::Decl
Decl - This represents one declaration (or definition), e.g.
Definition: DeclBase.h:87
clang::MethodVFTableLocation::VFPtrOffset
CharUnits VFPtrOffset
This is the offset of the vfptr from the start of the last vbase, or the complete type if there are n...
Definition: VTableBuilder.h:485
clang::CXXMethodDecl::isVirtual
bool isVirtual() const
Definition: DeclCXX.h:2086
clang::MicrosoftVTableContext
Definition: VTableBuilder.h:509
clang::CXXBaseSpecifier::isVirtual
bool isVirtual() const
Determines whether the base class is a virtual base class (or not).
Definition: DeclCXX.h:245
clang::ThisAdjustment::VirtualAdjustment::Itanium
struct clang::ThisAdjustment::VirtualAdjustment::@133 Itanium
llvm::DenseSet
Definition: Sema.h:66
P
StringRef P
Definition: ASTMatchersInternal.cpp:439
clang::GlobalDecl::getCanonicalDecl
GlobalDecl getCanonicalDecl() const
Definition: GlobalDecl.h:60
clang::ThisAdjustment::NonVirtual
int64_t NonVirtual
The non-virtual adjustment from the derived object to its nearest virtual base.
Definition: ABI.h:111
clang::CanQual::getUnqualifiedType
CanQual< T > getUnqualifiedType() const
Retrieve the unqualified form of this type.
Definition: CanonicalType.h:619
clang::ASTContext::getDiagnostics
DiagnosticsEngine & getDiagnostics() const
Definition: ASTContext.cpp:1335
clang::CXXRecordDecl::isDerivedFrom
bool isDerivedFrom(const CXXRecordDecl *Base) const
Determine whether this class is derived from the class Base.
Definition: CXXInheritance.cpp:92
clang::DiagnosticsEngine::Report
DiagnosticBuilder Report(SourceLocation Loc, unsigned DiagID)
Issue the message to the client.
Definition: Diagnostic.h:1295
CXXInheritance.h
clang::CharUnits::isZero
bool isZero() const
isZero - Test whether the quantity equals zero.
Definition: CharUnits.h:116
clang::ASTContext::getTargetInfo
const TargetInfo & getTargetInfo() const
Definition: ASTContext.h:690
Specifier
const NestedNameSpecifier * Specifier
Definition: USRLocFinder.cpp:173
clang::VPtrInfo::MangledPath
BasePath MangledPath
The bases from the inheritance path that got used to mangle the vbtable name.
Definition: VTableBuilder.h:434
clang::CXXBasePath
Represents a path from a specific derived class (which is not represented as part of the path) to a p...
Definition: CXXInheritance.h:71
CreateVTableLayout
static std::unique_ptr< VTableLayout > CreateVTableLayout(const ItaniumVTableBuilder &Builder)
Definition: VTableBuilder.cpp:2267
clang::VTableComponent::MakeUnusedFunction
static VTableComponent MakeUnusedFunction(const CXXMethodDecl *MD)
Definition: VTableBuilder.h:89
clang::VTableComponent::getUnusedFunctionDecl
const CXXMethodDecl * getUnusedFunctionDecl() const
Definition: VTableBuilder.h:136
clang::VTableComponent::CK_VCallOffset
Definition: VTableBuilder.h:33
clang::FunctionDecl::getReturnType
QualType getReturnType() const
Definition: Decl.h:2302
clang::MethodVFTableLocation::VBase
const CXXRecordDecl * VBase
If nonnull, holds the last vbase which contains the vfptr that the method definition is adjusted to...
Definition: VTableBuilder.h:481
clang::Type::getAs
const T * getAs() const
Member-template getAs<specific type>&#39;.
Definition: Type.h:6748
clang::DeclContext::decls
decl_range decls() const
decls_begin/decls_end - Iterate over the declarations stored in this context.
Definition: DeclBase.h:1997
clang::VTableComponent::MakeVCallOffset
static VTableComponent MakeVCallOffset(CharUnits Offset)
Definition: VTableBuilder.h:55
clang::ThisAdjustment
A this pointer adjustment.
Definition: ABI.h:108
clang::ThunkInfo::Method
const CXXMethodDecl * Method
Holds a pointer to the overridden method this thunk is for, if needed by the ABI to distinguish diffe...
Definition: ABI.h:191
clang::ReturnAdjustment::VirtualAdjustment::Itanium
struct clang::ReturnAdjustment::VirtualAdjustment::@131 Itanium
clang::BaseSubobject::getBaseOffset
CharUnits getBaseOffset() const
getBaseOffset - Returns the base class offset.
Definition: BaseSubobject.h:47
clang::TargetInfo::getPointerWidth
uint64_t getPointerWidth(unsigned AddrSpace) const
Return the width of pointers on this target, for the specified address space.
Definition: TargetInfo.h:349
clang::ThisAdjustment::VirtualAdjustment::VBOffsetOffset
int32_t VBOffsetOffset
The offset (in bytes) of the vbase offset in the vbtable.
Definition: ABI.h:132
clang::NamedDecl::getDeclName
DeclarationName getDeclName() const
Get the actual, stored name of the declaration, which may be a special name.
Definition: Decl.h:298
clang::TargetInfo::getCXXABI
TargetCXXABI getCXXABI() const
Get the C++ ABI currently in use.
Definition: TargetInfo.h:1022
clang::ASTContext
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:155
clang::FunctionProtoType::getParamTypes
ArrayRef< QualType > getParamTypes() const
Definition: Type.h:3895
clang::ItaniumVTableContext
Definition: VTableBuilder.h:348
clang::CXXMethodDecl::getCanonicalDecl
CXXMethodDecl * getCanonicalDecl() override
Retrieves the "canonical" declaration of the given declaration.
Definition: DeclCXX.h:2127
clang::VTableComponent::MakeCompleteDtor
static VTableComponent MakeCompleteDtor(const CXXDestructorDecl *DD)
Definition: VTableBuilder.h:79
clang::ReturnAdjustment
A return adjustment.
Definition: ABI.h:42
clang::CharUnits::Zero
static CharUnits Zero()
Zero - Construct a CharUnits quantity of zero.
Definition: CharUnits.h:53
clang::VirtualBaseInfo::VBTableIndices
llvm::DenseMap< const CXXRecordDecl *, unsigned > VBTableIndices
A map from virtual base to vbtable index for doing a conversion from the the derived class to the a b...
Definition: VTableBuilder.h:468
clang::ASTRecordLayout::getVBaseClassOffset
CharUnits getVBaseClassOffset(const CXXRecordDecl *VBase) const
getVBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:241
clang::ThunkInfo
The this pointer adjustment as well as an optional return adjustment for a thunk. ...
Definition: ABI.h:179
clang::VPtrInfo::NextBaseToMangle
const CXXRecordDecl * NextBaseToMangle
The next base to push onto the mangled path if this path is ambiguous in a derived class...
Definition: VTableBuilder.h:438
llvm::SmallVectorImpl
Definition: LLVM.h:37
clang::VTableComponent::CK_RTTI
Definition: VTableBuilder.h:36
clang::ItaniumVTableContext::~ItaniumVTableContext
~ItaniumVTableContext() override
Definition: VTableBuilder.cpp:2221
clang::OverridingMethods
The set of methods that override a given virtual method in each subobject where it occurs...
Definition: CXXInheritance.h:281
clang::CharUnits
CharUnits - This is an opaque type for sizes expressed in character units.
Definition: CharUnits.h:38
clang::VTableContextBase::ThunksMapTy
llvm::DenseMap< const CXXMethodDecl *, ThunkInfoVectorTy > ThunksMapTy
Definition: VTableBuilder.h:318
clang::MicrosoftVTableContext::~MicrosoftVTableContext
~MicrosoftVTableContext() override
Definition: VTableBuilder.cpp:3369
dump
static void dump(llvm::raw_ostream &OS, StringRef FunctionName, ArrayRef< CounterExpression > Expressions, ArrayRef< CounterMappingRegion > Regions)
Definition: CoverageMappingGen.cpp:1291
clang::VPtrInfo::IntroducingObject
const CXXRecordDecl * IntroducingObject
This is the class that introduced the vptr by declaring new virtual methods or virtual bases...
Definition: VTableBuilder.h:424
clang::ComparisonCategoryType::First
clang::Dtor_Deleting
Deleting dtor.
Definition: ABI.h:35
clang::DiagnosticsEngine
Concrete class used by the front-end to report problems and issues.
Definition: Diagnostic.h:149
clang::VTableComponent::CK_VBaseOffset
Definition: VTableBuilder.h:34
clang::MicrosoftVTableContext::getVFPtrOffsets
const VPtrInfoVector & getVFPtrOffsets(const CXXRecordDecl *RD)
Definition: VTableBuilder.cpp:3714
clang::CXXRecordDecl::bases_begin
base_class_iterator bases_begin()
Definition: DeclCXX.h:830
removeRedundantPaths
static void removeRedundantPaths(std::list< FullPathTy > &FullPaths)
Definition: VTableBuilder.cpp:3404
clang::ReturnAdjustment::VirtualAdjustment::Microsoft
struct clang::ReturnAdjustment::VirtualAdjustment::@132 Microsoft
llvm::ArrayRef
Definition: LLVM.h:32
clang::ItaniumVTableContext::getMethodVTableIndex
uint64_t getMethodVTableIndex(GlobalDecl GD)
Locate a virtual function in the vtable.
Definition: VTableBuilder.cpp:2223
clang::ItaniumVTableContext::getVirtualBaseOffsetOffset
CharUnits getVirtualBaseOffsetOffset(const CXXRecordDecl *RD, const CXXRecordDecl *VBase)
Return the offset in chars (relative to the vtable address point) where the offset of the virtual bas...
Definition: VTableBuilder.cpp:2239
clang::FunctionProtoType::getTypeQuals
Qualifiers getTypeQuals() const
Definition: Type.h:4015
setsIntersect
static bool setsIntersect(const llvm::SmallPtrSet< const CXXRecordDecl *, 4 > &A, ArrayRef< const CXXRecordDecl *> B)
Definition: VTableBuilder.cpp:3217
clang::VTableComponent::MakeDeletingDtor
static VTableComponent MakeDeletingDtor(const CXXDestructorDecl *DD)
Definition: VTableBuilder.h:84
clang::Type::getAsCXXRecordDecl
CXXRecordDecl * getAsCXXRecordDecl() const
Retrieves the CXXRecordDecl that this type refers to, either because the type is a RecordType or beca...
Definition: Type.cpp:1613
clang::FunctionProtoType
Represents a prototype with parameter type info, e.g.
Definition: Type.h:3687
clang::CXXRecordDecl::isDynamicClass
bool isDynamicClass() const
Definition: DeclCXX.h:789
clang::ReturnAdjustment::Virtual
union clang::ReturnAdjustment::VirtualAdjustment Virtual
clang::CharUnits::getQuantity
QuantityType getQuantity() const
getQuantity - Get the raw integer representation of this quantity.
Definition: CharUnits.h:179
Offset
unsigned Offset
Definition: Format.cpp:1631
clang::ASTRecordLayout
ASTRecordLayout - This class contains layout information for one RecordDecl, which is a struct/union/...
Definition: RecordLayout.h:39
GroupNewVirtualOverloads
static void GroupNewVirtualOverloads(const CXXRecordDecl *RD, SmallVector< const CXXMethodDecl *, 10 > &VirtualMethods)
Definition: VTableBuilder.cpp:2854
clang::VTableContextBase::ThunkInfoVectorTy
SmallVector< ThunkInfo, 1 > ThunkInfoVectorTy
Definition: VTableBuilder.h:311
clang::VTableComponent::CK_FunctionPointer
Definition: VTableBuilder.h:37
clang::VTableComponent::getKind
Kind getKind() const
Get the kind of this vtable component.
Definition: VTableBuilder.h:97
clang::CXXRecordDecl::getFinalOverriders
void getFinalOverriders(CXXFinalOverriderMap &FinaOverriders) const
Retrieve the final overriders for each virtual member function in the class hierarchy where this clas...
Definition: CXXInheritance.cpp:718
clang::CXXDestructorDecl
Represents a C++ destructor within a class.
Definition: DeclCXX.h:2706
clang::Decl::isImplicit
bool isImplicit() const
isImplicit - Indicates whether the declaration was implicitly generated by the implementation.
Definition: DeclBase.h:547
clang::diff::Insert
Definition: ASTDiff.h:32
clang::CXXMethodDecl::overridden_methods
overridden_method_range overridden_methods() const
Definition: DeclCXX.cpp:2170
clang::VTableComponent::getOffsetToTop
CharUnits getOffsetToTop() const
Definition: VTableBuilder.h:113
clang::VTableComponent::getVCallOffset
CharUnits getVCallOffset() const
Definition: VTableBuilder.h:101
clang::ASTRecordLayout::getPrimaryBase
const CXXRecordDecl * getPrimaryBase() const
getPrimaryBase - Get the primary base for this record.
Definition: RecordLayout.h:218
clang::CharUnits::fromQuantity
static CharUnits fromQuantity(QuantityType Quantity)
fromQuantity - Construct a CharUnits quantity from a raw integer type.
Definition: CharUnits.h:63
clang::ast_matchers::id
internal::Matcher< T > id(StringRef ID, const internal::BindableMatcher< T > &InnerMatcher)
If the provided matcher matches a node, binds the node to ID.
Definition: ASTMatchers.h:137
findPathsToSubobject
static void findPathsToSubobject(ASTContext &Context, const ASTRecordLayout &MostDerivedLayout, const CXXRecordDecl *RD, CharUnits Offset, BaseSubobject IntroducingObject, FullPathTy &FullPath, std::list< FullPathTy > &Paths)
Definition: VTableBuilder.cpp:3378
clang::BaseSubobject::getBase
const CXXRecordDecl * getBase() const
getBase - Returns the base class declaration.
Definition: BaseSubobject.h:44
clang::CXXRecordDecl::isPolymorphic
bool isPolymorphic() const
Whether this class is polymorphic (C++ [class.virtual]), which means that the class contains or inher...
Definition: DeclCXX.h:1337
clang::BaseSubobject
Definition: BaseSubobject.h:31
clang::DeclContext::getParent
DeclContext * getParent()
getParent - Returns the containing DeclContext.
Definition: DeclBase.h:1752
clang::VTableComponent::getDestructorDecl
const CXXDestructorDecl * getDestructorDecl() const
Definition: VTableBuilder.h:131
clang::UniqueVirtualMethod
Uniquely identifies a virtual method within a class hierarchy by the method itself and a class subobj...
Definition: CXXInheritance.h:242
clang::VTableLayout::AddressPointLocation
Definition: VTableBuilder.h:236
clang::ASTRecordLayout::getVBPtrOffset
CharUnits getVBPtrOffset() const
getVBPtrOffset - Get the offset for virtual base table pointer.
Definition: RecordLayout.h:306
clang::NamedDecl::printQualifiedName
void printQualifiedName(raw_ostream &OS) const
Returns a human-readable qualified name for this declaration, like A::B::i, for i being member of nam...
Definition: Decl.cpp:1527
clang::GlobalDecl
GlobalDecl - represents a global declaration.
Definition: GlobalDecl.h:35
PrintBasePath
static void PrintBasePath(const VPtrInfo::BasePath &Path, raw_ostream &Out)
Definition: VTableBuilder.cpp:3053
clang::ThisAdjustment::VirtualAdjustment::isEmpty
bool isEmpty() const
Definition: ABI.h:143
clang::ReturnAdjustment::NonVirtual
int64_t NonVirtual
The non-virtual adjustment from the derived object to its nearest virtual base.
Definition: ABI.h:45
clang::MicrosoftVTableContext::getVBTableIndex
unsigned getVBTableIndex(const CXXRecordDecl *Derived, const CXXRecordDecl *VBase)
Returns the index of VBase in the vbtable of Derived.
Definition: VTableBuilder.cpp:3701
clang::CXXBasePathElement::Base
const CXXBaseSpecifier * Base
The base specifier that states the link from a derived class to a base class, which will be followed ...
Definition: CXXInheritance.h:49
false
#define false
Definition: stdbool.h:33
clang::QualType::getCanonicalType
QualType getCanonicalType() const
Definition: Type.h:6111
rebucketPaths
static bool rebucketPaths(VPtrInfoVector &Paths)
Definition: VTableBuilder.cpp:3335
clang::ItaniumVTableContext::createConstructionVTableLayout
std::unique_ptr< VTableLayout > createConstructionVTableLayout(const CXXRecordDecl *MostDerivedClass, CharUnits MostDerivedClassOffset, bool MostDerivedClassIsVirtual, const CXXRecordDecl *LayoutClass)
Definition: VTableBuilder.cpp:2315
llvm::OwningArrayRef
Definition: LLVM.h:34
clang::FunctionType::getReturnType
QualType getReturnType() const
Definition: Type.h:3613
clang::FunctionDecl::isPure
bool isPure() const
Whether this virtual function is pure, i.e.
Definition: Decl.h:2009
clang::MethodVFTableLocation
Definition: VTableBuilder.h:475
dumpMicrosoftThunkAdjustment
static void dumpMicrosoftThunkAdjustment(const ThunkInfo &TI, raw_ostream &Out, bool ContinueFirstLine)
Definition: VTableBuilder.cpp:3062
clang::Decl::getASTContext
ASTContext & getASTContext() const LLVM_READONLY
Definition: DeclBase.cpp:376
vfptrIsEarlierInMDC
static bool vfptrIsEarlierInMDC(const ASTRecordLayout &Layout, const MethodVFTableLocation &LHS, const MethodVFTableLocation &RHS)
Definition: VTableBuilder.cpp:3543
clang::GlobalDecl::getDecl
const Decl * getDecl() const
Definition: GlobalDecl.h:69
llvm::SmallSetVector
Definition: ExternalSemaSource.h:24
clang::VTableComponent
Represents a single component in a vtable.
Definition: VTableBuilder.h:30
clang::CXXMethodDecl
Represents a static or instance method of a struct/union/class.
Definition: DeclCXX.h:2041
ASTDiagnostic.h
clang::PredefinedExpr::ComputeName
static std::string ComputeName(IdentKind IK, const Decl *CurrentDecl)
Definition: Expr.cpp:537
clang::MicrosoftVTableContext::getVFTableLayout
const VTableLayout & getVFTableLayout(const CXXRecordDecl *RD, CharUnits VFPtrOffset)
Definition: VTableBuilder.cpp:3722
clang::CanQual< Type >
llvm::SmallVector
Definition: LLVM.h:36
clang::PredefinedExpr::PrettyFunctionNoVirtual
The same as PrettyFunction, except that the &#39;virtual&#39; keyword is omitted for virtual member functions...
Definition: Expr.h:1779
clang::DiagnosticsEngine::getCustomDiagID
unsigned getCustomDiagID(Level L, const char(&FormatString)[N])
Return an ID for a diagnostic with the specified format string and level.
Definition: Diagnostic.h:776
clang::ThisAdjustment::VirtualAdjustment::VCallOffsetOffset
int64_t VCallOffsetOffset
The offset (in bytes), relative to the address point, of the virtual call offset. ...
Definition: ABI.h:120
clang::Dtor_Complete
Complete object dtor.
Definition: ABI.h:36
clang::VTableComponent::getRTTIDecl
const CXXRecordDecl * getRTTIDecl() const
Definition: VTableBuilder.h:119
clang::CanQual::getAs
CanProxy< U > getAs() const
Retrieve a canonical type pointer with a different static type, upcasting or downcasting as needed...
Definition: CanonicalType.h:652
clang::VTableComponent::MakeVBaseOffset
static VTableComponent MakeVBaseOffset(CharUnits Offset)
Definition: VTableBuilder.h:59
clang::CXXBasePathElement
Represents an element in a path from a derived class to a base class.
Definition: CXXInheritance.h:45
clang
Dataflow Directional Tag Classes.
Definition: CFGReachabilityAnalysis.h:22
clang::ThunkInfo::This
ThisAdjustment This
The this pointer adjustment.
Definition: ABI.h:181
clang::MicrosoftVTableContext::enumerateVBTables
const VPtrInfoVector & enumerateVBTables(const CXXRecordDecl *RD)
Definition: VTableBuilder.cpp:3709
clang::VTableContextBase
Definition: VTableBuilder.h:309
isDirectVBase
static bool isDirectVBase(const CXXRecordDecl *Base, const CXXRecordDecl *RD)
Definition: VTableBuilder.cpp:2886
clang::VTableContextBase::Thunks
ThunksMapTy Thunks
Contains all thunks that a given method decl will need.
Definition: VTableBuilder.h:321
extendPath
static bool extendPath(VPtrInfo &P)
Definition: VTableBuilder.cpp:3326
clang::DeclarationName
The name of a declaration.
Definition: DeclarationName.h:146
clang::QualType::getAsString
static std::string getAsString(SplitQualType split, const PrintingPolicy &Policy)
Definition: Type.h:971
clang::CXXMethodDecl::getParent
const CXXRecordDecl * getParent() const
Returns the parent of this method declaration, which is the class in which this method is defined...
Definition: DeclCXX.h:2166
clang::ASTRecordLayout::getBaseSharingVBPtr
const CXXRecordDecl * getBaseSharingVBPtr() const
Definition: RecordLayout.h:311
clang::CXXFinalOverriderMap
A mapping from each virtual member function to its set of final overriders.
Definition: CXXInheritance.h:369
getOffsetOfFullPath
static CharUnits getOffsetOfFullPath(ASTContext &Context, const CXXRecordDecl *RD, const FullPathTy &FullPath)
Definition: VTableBuilder.cpp:3419
clang::ReturnAdjustment::VirtualAdjustment::VBaseOffsetOffset
int64_t VBaseOffsetOffset
The offset (in bytes), relative to the address point of the virtual base class offset.
Definition: ABI.h:54
clang::VPtrInfo::NonVirtualOffset
CharUnits NonVirtualOffset
IntroducingObject is at this offset from its containing complete object or virtual base...
Definition: VTableBuilder.h:428
clang::CXXRecordDecl::vbases_begin
base_class_iterator vbases_begin()
Definition: DeclCXX.h:847
clang::VTableComponent::CK_OffsetToTop
Definition: VTableBuilder.h:35
clang::ThunkInfo::isEmpty
bool isEmpty() const
Definition: ABI.h:204
clang::VirtualBaseInfo
All virtual base related information about a given record decl.
Definition: VTableBuilder.h:465
clang::ThisAdjustment::Virtual
union clang::ThisAdjustment::VirtualAdjustment Virtual
clang::VTableLayout::VTableLayout
VTableLayout(ArrayRef< size_t > VTableIndices, ArrayRef< VTableComponent > VTableComponents, ArrayRef< VTableThunkTy > VTableThunks, const AddressPointsMapTy &AddressPoints)
Definition: VTableBuilder.cpp:2197
clang::DiagnosticsEngine::Error
Definition: Diagnostic.h:157
clang::VPtrInfo::getVBaseWithVPtr
const CXXRecordDecl * getVBaseWithVPtr() const
The vptr is stored inside the non-virtual component of this virtual base.
Definition: VTableBuilder.h:455
clang::VTableLayout::~VTableLayout
~VTableLayout()
Definition: VTableBuilder.cpp:2216
clang::CXXBasePaths::front
CXXBasePath & front()
Definition: CXXInheritance.h:197
selectBestPath
static const FullPathTy * selectBestPath(ASTContext &Context, const CXXRecordDecl *RD, const VPtrInfo &Info, std::list< FullPathTy > &FullPaths)
Definition: VTableBuilder.cpp:3451
clang::ReferenceType
Base for LValueReferenceType and RValueReferenceType.
Definition: Type.h:2673
clang::ThunkInfo::Return
ReturnAdjustment Return
The return adjustment.
Definition: ABI.h:184
clang::CXXBaseSpecifier
Represents a base class of a C++ class.
Definition: DeclCXX.h:192
clang::ASTContext::getCanonicalType
CanQualType getCanonicalType(QualType T) const
Return the canonical (structural) type corresponding to the specified potentially non-canonical type ...
Definition: ASTContext.h:2253
clang::ASTContext::toCharUnitsFromBits
CharUnits toCharUnitsFromBits(int64_t BitSize) const
Convert a size in bits to a size in characters.
Definition: ASTContext.cpp:2156
clang::VTableLayout::AddressPointsMapTy
llvm::DenseMap< BaseSubobject, AddressPointLocation > AddressPointsMapTy
Definition: VTableBuilder.h:240
clang::CXXRecordDecl
Represents a C++ struct/union/class.
Definition: DeclCXX.h:300
RecordLayout.h
clang::ThisAdjustment::VirtualAdjustment::VtordispOffset
int32_t VtordispOffset
The offset of the vtordisp (in bytes), relative to the ECX.
Definition: ABI.h:125
clang::CXXRecordDecl::bases_end
base_class_iterator bases_end()
Definition: DeclCXX.h:832
LT
ASTImporterLookupTable & LT
Definition: ASTImporterLookupTable.cpp:24
clang::VTableLayout
Definition: VTableBuilder.h:233
clang::VTableLayout::VTableThunkTy
std::pair< uint64_t, ThunkInfo > VTableThunkTy
Definition: VTableBuilder.h:235
clang::ASTRecordLayout::VBaseOffsetsMapTy
llvm::DenseMap< const CXXRecordDecl *, VBaseInfo > VBaseOffsetsMapTy
Definition: RecordLayout.h:60
TargetInfo.h
Defines the clang::TargetInfo interface.
clang::TargetCXXABI::isMicrosoft
bool isMicrosoft() const
Is this ABI an MSVC-compatible ABI?
Definition: TargetCXXABI.h:154
clang::VTableComponent::CK_DeletingDtorPointer
A pointer to the deleting destructor.
Definition: VTableBuilder.h:43
getKind
static Decl::Kind getKind(const Decl *D)
Definition: DeclBase.cpp:954
clang::ASTContext::IntTy
CanQualType IntTy
Definition: ASTContext.h:1025
clang::MicrosoftVTableContext::getMethodVFTableLocation
MethodVFTableLocation getMethodVFTableLocation(GlobalDecl GD)
Definition: VTableBuilder.cpp:3732
clang::VTableComponent::MakeFunction
static VTableComponent MakeFunction(const CXXMethodDecl *MD)
Definition: VTableBuilder.h:71
clang::FunctionDecl::isDeleted
bool isDeleted() const
Whether this function has been deleted.
Definition: Decl.h:2136
clang::VPtrInfo
Holds information about the inheritance path to a virtual base or function table pointer.
Definition: VTableBuilder.h:411
clang::CXXBasePaths
BasePaths - Represents the set of paths from a derived class to one of its (direct or indirect) bases...
Definition: CXXInheritance.h:119
clang::ASTContext::getTypeSizeInChars
CharUnits getTypeSizeInChars(QualType T) const
Return the size of the specified (complete) type T, in characters.
Definition: ASTContext.cpp:2167
VTableBuilder.h
clang::ValueDecl::getType
QualType getType() const
Definition: Decl.h:648
clang::ReturnAdjustment::VirtualAdjustment::VBIndex
uint32_t VBIndex
Index of the virtual base in the vbtable.
Definition: ABI.h:64
clang::NamedDecl
This represents a decl that may have a name.
Definition: Decl.h:249
clang::VTableComponent::getVBaseOffset
CharUnits getVBaseOffset() const
Definition: VTableBuilder.h:107
computeFullPathsForVFTables
static void computeFullPathsForVFTables(ASTContext &Context, const CXXRecordDecl *RD, VPtrInfoVector &Paths)
Definition: VTableBuilder.cpp:3521
clang::CXXBasePathElement::Class
const CXXRecordDecl * Class
The record decl of the class that the base is a base of.
Definition: CXXInheritance.h:52
clang::ThisAdjustment::VirtualAdjustment::VBPtrOffset
int32_t VBPtrOffset
The offset of the vbptr of the derived class (in bytes), relative to the ECX after vtordisp adjustmen...
Definition: ABI.h:129
clang::ASTContext::getLangOpts
const LangOptions & getLangOpts() const
Definition: ASTContext.h:707
clang::CXXRecordDecl::vbases
base_class_range vbases()
Definition: DeclCXX.h:840
clang::VTableComponent::CK_CompleteDtorPointer
A pointer to the complete destructor.
Definition: VTableBuilder.h:40
clang::ThisAdjustment::VirtualAdjustment::Microsoft
struct clang::ThisAdjustment::VirtualAdjustment::@134 Microsoft
clang::VTableComponent::CK_UnusedFunctionPointer
An entry that is never used.
Definition: VTableBuilder.h:50
clang::Decl::getLocation
SourceLocation getLocation() const
Definition: DeclBase.h:418
clang::CXXRecordDecl::methods
method_range methods() const
Definition: DeclCXX.h:865
clang::CXXBaseSpecifier::getType
QualType getType() const
Retrieves the type of the base class.
Definition: DeclCXX.h:291
clang::VTableComponent::MakeOffsetToTop
static VTableComponent MakeOffsetToTop(CharUnits Offset)
Definition: VTableBuilder.h:63