clang  8.0.0svn
RecordLayoutBuilder.cpp
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1 //=== RecordLayoutBuilder.cpp - Helper class for building record layouts ---==//
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 #include "clang/AST/RecordLayout.h"
11 #include "clang/AST/ASTContext.h"
12 #include "clang/AST/Attr.h"
14 #include "clang/AST/Decl.h"
15 #include "clang/AST/DeclCXX.h"
16 #include "clang/AST/DeclObjC.h"
17 #include "clang/AST/Expr.h"
18 #include "clang/Basic/TargetInfo.h"
20 #include "llvm/ADT/SmallSet.h"
21 #include "llvm/Support/Format.h"
22 #include "llvm/Support/MathExtras.h"
23 
24 using namespace clang;
25 
26 namespace {
27 
28 /// BaseSubobjectInfo - Represents a single base subobject in a complete class.
29 /// For a class hierarchy like
30 ///
31 /// class A { };
32 /// class B : A { };
33 /// class C : A, B { };
34 ///
35 /// The BaseSubobjectInfo graph for C will have three BaseSubobjectInfo
36 /// instances, one for B and two for A.
37 ///
38 /// If a base is virtual, it will only have one BaseSubobjectInfo allocated.
39 struct BaseSubobjectInfo {
40  /// Class - The class for this base info.
41  const CXXRecordDecl *Class;
42 
43  /// IsVirtual - Whether the BaseInfo represents a virtual base or not.
44  bool IsVirtual;
45 
46  /// Bases - Information about the base subobjects.
48 
49  /// PrimaryVirtualBaseInfo - Holds the base info for the primary virtual base
50  /// of this base info (if one exists).
51  BaseSubobjectInfo *PrimaryVirtualBaseInfo;
52 
53  // FIXME: Document.
54  const BaseSubobjectInfo *Derived;
55 };
56 
57 /// Externally provided layout. Typically used when the AST source, such
58 /// as DWARF, lacks all the information that was available at compile time, such
59 /// as alignment attributes on fields and pragmas in effect.
60 struct ExternalLayout {
61  ExternalLayout() : Size(0), Align(0) {}
62 
63  /// Overall record size in bits.
64  uint64_t Size;
65 
66  /// Overall record alignment in bits.
67  uint64_t Align;
68 
69  /// Record field offsets in bits.
70  llvm::DenseMap<const FieldDecl *, uint64_t> FieldOffsets;
71 
72  /// Direct, non-virtual base offsets.
73  llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsets;
74 
75  /// Virtual base offsets.
76  llvm::DenseMap<const CXXRecordDecl *, CharUnits> VirtualBaseOffsets;
77 
78  /// Get the offset of the given field. The external source must provide
79  /// entries for all fields in the record.
80  uint64_t getExternalFieldOffset(const FieldDecl *FD) {
81  assert(FieldOffsets.count(FD) &&
82  "Field does not have an external offset");
83  return FieldOffsets[FD];
84  }
85 
86  bool getExternalNVBaseOffset(const CXXRecordDecl *RD, CharUnits &BaseOffset) {
87  auto Known = BaseOffsets.find(RD);
88  if (Known == BaseOffsets.end())
89  return false;
90  BaseOffset = Known->second;
91  return true;
92  }
93 
94  bool getExternalVBaseOffset(const CXXRecordDecl *RD, CharUnits &BaseOffset) {
95  auto Known = VirtualBaseOffsets.find(RD);
96  if (Known == VirtualBaseOffsets.end())
97  return false;
98  BaseOffset = Known->second;
99  return true;
100  }
101 };
102 
103 /// EmptySubobjectMap - Keeps track of which empty subobjects exist at different
104 /// offsets while laying out a C++ class.
105 class EmptySubobjectMap {
106  const ASTContext &Context;
107  uint64_t CharWidth;
108 
109  /// Class - The class whose empty entries we're keeping track of.
110  const CXXRecordDecl *Class;
111 
112  /// EmptyClassOffsets - A map from offsets to empty record decls.
113  typedef llvm::TinyPtrVector<const CXXRecordDecl *> ClassVectorTy;
114  typedef llvm::DenseMap<CharUnits, ClassVectorTy> EmptyClassOffsetsMapTy;
115  EmptyClassOffsetsMapTy EmptyClassOffsets;
116 
117  /// MaxEmptyClassOffset - The highest offset known to contain an empty
118  /// base subobject.
119  CharUnits MaxEmptyClassOffset;
120 
121  /// ComputeEmptySubobjectSizes - Compute the size of the largest base or
122  /// member subobject that is empty.
123  void ComputeEmptySubobjectSizes();
124 
125  void AddSubobjectAtOffset(const CXXRecordDecl *RD, CharUnits Offset);
126 
127  void UpdateEmptyBaseSubobjects(const BaseSubobjectInfo *Info,
128  CharUnits Offset, bool PlacingEmptyBase);
129 
130  void UpdateEmptyFieldSubobjects(const CXXRecordDecl *RD,
131  const CXXRecordDecl *Class,
132  CharUnits Offset);
133  void UpdateEmptyFieldSubobjects(const FieldDecl *FD, CharUnits Offset);
134 
135  /// AnyEmptySubobjectsBeyondOffset - Returns whether there are any empty
136  /// subobjects beyond the given offset.
137  bool AnyEmptySubobjectsBeyondOffset(CharUnits Offset) const {
138  return Offset <= MaxEmptyClassOffset;
139  }
140 
141  CharUnits
142  getFieldOffset(const ASTRecordLayout &Layout, unsigned FieldNo) const {
143  uint64_t FieldOffset = Layout.getFieldOffset(FieldNo);
144  assert(FieldOffset % CharWidth == 0 &&
145  "Field offset not at char boundary!");
146 
147  return Context.toCharUnitsFromBits(FieldOffset);
148  }
149 
150 protected:
151  bool CanPlaceSubobjectAtOffset(const CXXRecordDecl *RD,
152  CharUnits Offset) const;
153 
154  bool CanPlaceBaseSubobjectAtOffset(const BaseSubobjectInfo *Info,
155  CharUnits Offset);
156 
157  bool CanPlaceFieldSubobjectAtOffset(const CXXRecordDecl *RD,
158  const CXXRecordDecl *Class,
159  CharUnits Offset) const;
160  bool CanPlaceFieldSubobjectAtOffset(const FieldDecl *FD,
161  CharUnits Offset) const;
162 
163 public:
164  /// This holds the size of the largest empty subobject (either a base
165  /// or a member). Will be zero if the record being built doesn't contain
166  /// any empty classes.
167  CharUnits SizeOfLargestEmptySubobject;
168 
169  EmptySubobjectMap(const ASTContext &Context, const CXXRecordDecl *Class)
170  : Context(Context), CharWidth(Context.getCharWidth()), Class(Class) {
171  ComputeEmptySubobjectSizes();
172  }
173 
174  /// CanPlaceBaseAtOffset - Return whether the given base class can be placed
175  /// at the given offset.
176  /// Returns false if placing the record will result in two components
177  /// (direct or indirect) of the same type having the same offset.
178  bool CanPlaceBaseAtOffset(const BaseSubobjectInfo *Info,
179  CharUnits Offset);
180 
181  /// CanPlaceFieldAtOffset - Return whether a field can be placed at the given
182  /// offset.
183  bool CanPlaceFieldAtOffset(const FieldDecl *FD, CharUnits Offset);
184 };
185 
186 void EmptySubobjectMap::ComputeEmptySubobjectSizes() {
187  // Check the bases.
188  for (const CXXBaseSpecifier &Base : Class->bases()) {
189  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
190 
191  CharUnits EmptySize;
192  const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
193  if (BaseDecl->isEmpty()) {
194  // If the class decl is empty, get its size.
195  EmptySize = Layout.getSize();
196  } else {
197  // Otherwise, we get the largest empty subobject for the decl.
198  EmptySize = Layout.getSizeOfLargestEmptySubobject();
199  }
200 
201  if (EmptySize > SizeOfLargestEmptySubobject)
202  SizeOfLargestEmptySubobject = EmptySize;
203  }
204 
205  // Check the fields.
206  for (const FieldDecl *FD : Class->fields()) {
207  const RecordType *RT =
208  Context.getBaseElementType(FD->getType())->getAs<RecordType>();
209 
210  // We only care about record types.
211  if (!RT)
212  continue;
213 
214  CharUnits EmptySize;
215  const CXXRecordDecl *MemberDecl = RT->getAsCXXRecordDecl();
216  const ASTRecordLayout &Layout = Context.getASTRecordLayout(MemberDecl);
217  if (MemberDecl->isEmpty()) {
218  // If the class decl is empty, get its size.
219  EmptySize = Layout.getSize();
220  } else {
221  // Otherwise, we get the largest empty subobject for the decl.
222  EmptySize = Layout.getSizeOfLargestEmptySubobject();
223  }
224 
225  if (EmptySize > SizeOfLargestEmptySubobject)
226  SizeOfLargestEmptySubobject = EmptySize;
227  }
228 }
229 
230 bool
231 EmptySubobjectMap::CanPlaceSubobjectAtOffset(const CXXRecordDecl *RD,
232  CharUnits Offset) const {
233  // We only need to check empty bases.
234  if (!RD->isEmpty())
235  return true;
236 
237  EmptyClassOffsetsMapTy::const_iterator I = EmptyClassOffsets.find(Offset);
238  if (I == EmptyClassOffsets.end())
239  return true;
240 
241  const ClassVectorTy &Classes = I->second;
242  if (std::find(Classes.begin(), Classes.end(), RD) == Classes.end())
243  return true;
244 
245  // There is already an empty class of the same type at this offset.
246  return false;
247 }
248 
249 void EmptySubobjectMap::AddSubobjectAtOffset(const CXXRecordDecl *RD,
250  CharUnits Offset) {
251  // We only care about empty bases.
252  if (!RD->isEmpty())
253  return;
254 
255  // If we have empty structures inside a union, we can assign both
256  // the same offset. Just avoid pushing them twice in the list.
257  ClassVectorTy &Classes = EmptyClassOffsets[Offset];
258  if (std::find(Classes.begin(), Classes.end(), RD) != Classes.end())
259  return;
260 
261  Classes.push_back(RD);
262 
263  // Update the empty class offset.
264  if (Offset > MaxEmptyClassOffset)
265  MaxEmptyClassOffset = Offset;
266 }
267 
268 bool
269 EmptySubobjectMap::CanPlaceBaseSubobjectAtOffset(const BaseSubobjectInfo *Info,
270  CharUnits Offset) {
271  // We don't have to keep looking past the maximum offset that's known to
272  // contain an empty class.
273  if (!AnyEmptySubobjectsBeyondOffset(Offset))
274  return true;
275 
276  if (!CanPlaceSubobjectAtOffset(Info->Class, Offset))
277  return false;
278 
279  // Traverse all non-virtual bases.
280  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
281  for (const BaseSubobjectInfo *Base : Info->Bases) {
282  if (Base->IsVirtual)
283  continue;
284 
285  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
286 
287  if (!CanPlaceBaseSubobjectAtOffset(Base, BaseOffset))
288  return false;
289  }
290 
291  if (Info->PrimaryVirtualBaseInfo) {
292  BaseSubobjectInfo *PrimaryVirtualBaseInfo = Info->PrimaryVirtualBaseInfo;
293 
294  if (Info == PrimaryVirtualBaseInfo->Derived) {
295  if (!CanPlaceBaseSubobjectAtOffset(PrimaryVirtualBaseInfo, Offset))
296  return false;
297  }
298  }
299 
300  // Traverse all member variables.
301  unsigned FieldNo = 0;
302  for (CXXRecordDecl::field_iterator I = Info->Class->field_begin(),
303  E = Info->Class->field_end(); I != E; ++I, ++FieldNo) {
304  if (I->isBitField())
305  continue;
306 
307  CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
308  if (!CanPlaceFieldSubobjectAtOffset(*I, FieldOffset))
309  return false;
310  }
311 
312  return true;
313 }
314 
315 void EmptySubobjectMap::UpdateEmptyBaseSubobjects(const BaseSubobjectInfo *Info,
316  CharUnits Offset,
317  bool PlacingEmptyBase) {
318  if (!PlacingEmptyBase && Offset >= SizeOfLargestEmptySubobject) {
319  // We know that the only empty subobjects that can conflict with empty
320  // subobject of non-empty bases, are empty bases that can be placed at
321  // offset zero. Because of this, we only need to keep track of empty base
322  // subobjects with offsets less than the size of the largest empty
323  // subobject for our class.
324  return;
325  }
326 
327  AddSubobjectAtOffset(Info->Class, Offset);
328 
329  // Traverse all non-virtual bases.
330  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
331  for (const BaseSubobjectInfo *Base : Info->Bases) {
332  if (Base->IsVirtual)
333  continue;
334 
335  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
336  UpdateEmptyBaseSubobjects(Base, BaseOffset, PlacingEmptyBase);
337  }
338 
339  if (Info->PrimaryVirtualBaseInfo) {
340  BaseSubobjectInfo *PrimaryVirtualBaseInfo = Info->PrimaryVirtualBaseInfo;
341 
342  if (Info == PrimaryVirtualBaseInfo->Derived)
343  UpdateEmptyBaseSubobjects(PrimaryVirtualBaseInfo, Offset,
344  PlacingEmptyBase);
345  }
346 
347  // Traverse all member variables.
348  unsigned FieldNo = 0;
349  for (CXXRecordDecl::field_iterator I = Info->Class->field_begin(),
350  E = Info->Class->field_end(); I != E; ++I, ++FieldNo) {
351  if (I->isBitField())
352  continue;
353 
354  CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
355  UpdateEmptyFieldSubobjects(*I, FieldOffset);
356  }
357 }
358 
359 bool EmptySubobjectMap::CanPlaceBaseAtOffset(const BaseSubobjectInfo *Info,
360  CharUnits Offset) {
361  // If we know this class doesn't have any empty subobjects we don't need to
362  // bother checking.
363  if (SizeOfLargestEmptySubobject.isZero())
364  return true;
365 
366  if (!CanPlaceBaseSubobjectAtOffset(Info, Offset))
367  return false;
368 
369  // We are able to place the base at this offset. Make sure to update the
370  // empty base subobject map.
371  UpdateEmptyBaseSubobjects(Info, Offset, Info->Class->isEmpty());
372  return true;
373 }
374 
375 bool
376 EmptySubobjectMap::CanPlaceFieldSubobjectAtOffset(const CXXRecordDecl *RD,
377  const CXXRecordDecl *Class,
378  CharUnits Offset) const {
379  // We don't have to keep looking past the maximum offset that's known to
380  // contain an empty class.
381  if (!AnyEmptySubobjectsBeyondOffset(Offset))
382  return true;
383 
384  if (!CanPlaceSubobjectAtOffset(RD, Offset))
385  return false;
386 
387  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
388 
389  // Traverse all non-virtual bases.
390  for (const CXXBaseSpecifier &Base : RD->bases()) {
391  if (Base.isVirtual())
392  continue;
393 
394  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
395 
396  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl);
397  if (!CanPlaceFieldSubobjectAtOffset(BaseDecl, Class, BaseOffset))
398  return false;
399  }
400 
401  if (RD == Class) {
402  // This is the most derived class, traverse virtual bases as well.
403  for (const CXXBaseSpecifier &Base : RD->vbases()) {
404  const CXXRecordDecl *VBaseDecl = Base.getType()->getAsCXXRecordDecl();
405 
406  CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl);
407  if (!CanPlaceFieldSubobjectAtOffset(VBaseDecl, Class, VBaseOffset))
408  return false;
409  }
410  }
411 
412  // Traverse all member variables.
413  unsigned FieldNo = 0;
414  for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
415  I != E; ++I, ++FieldNo) {
416  if (I->isBitField())
417  continue;
418 
419  CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
420 
421  if (!CanPlaceFieldSubobjectAtOffset(*I, FieldOffset))
422  return false;
423  }
424 
425  return true;
426 }
427 
428 bool
429 EmptySubobjectMap::CanPlaceFieldSubobjectAtOffset(const FieldDecl *FD,
430  CharUnits Offset) const {
431  // We don't have to keep looking past the maximum offset that's known to
432  // contain an empty class.
433  if (!AnyEmptySubobjectsBeyondOffset(Offset))
434  return true;
435 
436  QualType T = FD->getType();
437  if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
438  return CanPlaceFieldSubobjectAtOffset(RD, RD, Offset);
439 
440  // If we have an array type we need to look at every element.
441  if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) {
442  QualType ElemTy = Context.getBaseElementType(AT);
443  const RecordType *RT = ElemTy->getAs<RecordType>();
444  if (!RT)
445  return true;
446 
447  const CXXRecordDecl *RD = RT->getAsCXXRecordDecl();
448  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
449 
450  uint64_t NumElements = Context.getConstantArrayElementCount(AT);
451  CharUnits ElementOffset = Offset;
452  for (uint64_t I = 0; I != NumElements; ++I) {
453  // We don't have to keep looking past the maximum offset that's known to
454  // contain an empty class.
455  if (!AnyEmptySubobjectsBeyondOffset(ElementOffset))
456  return true;
457 
458  if (!CanPlaceFieldSubobjectAtOffset(RD, RD, ElementOffset))
459  return false;
460 
461  ElementOffset += Layout.getSize();
462  }
463  }
464 
465  return true;
466 }
467 
468 bool
469 EmptySubobjectMap::CanPlaceFieldAtOffset(const FieldDecl *FD,
470  CharUnits Offset) {
471  if (!CanPlaceFieldSubobjectAtOffset(FD, Offset))
472  return false;
473 
474  // We are able to place the member variable at this offset.
475  // Make sure to update the empty base subobject map.
476  UpdateEmptyFieldSubobjects(FD, Offset);
477  return true;
478 }
479 
480 void EmptySubobjectMap::UpdateEmptyFieldSubobjects(const CXXRecordDecl *RD,
481  const CXXRecordDecl *Class,
482  CharUnits Offset) {
483  // We know that the only empty subobjects that can conflict with empty
484  // field subobjects are subobjects of empty bases that can be placed at offset
485  // zero. Because of this, we only need to keep track of empty field
486  // subobjects with offsets less than the size of the largest empty
487  // subobject for our class.
488  if (Offset >= SizeOfLargestEmptySubobject)
489  return;
490 
491  AddSubobjectAtOffset(RD, Offset);
492 
493  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
494 
495  // Traverse all non-virtual bases.
496  for (const CXXBaseSpecifier &Base : RD->bases()) {
497  if (Base.isVirtual())
498  continue;
499 
500  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
501 
502  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl);
503  UpdateEmptyFieldSubobjects(BaseDecl, Class, BaseOffset);
504  }
505 
506  if (RD == Class) {
507  // This is the most derived class, traverse virtual bases as well.
508  for (const CXXBaseSpecifier &Base : RD->vbases()) {
509  const CXXRecordDecl *VBaseDecl = Base.getType()->getAsCXXRecordDecl();
510 
511  CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl);
512  UpdateEmptyFieldSubobjects(VBaseDecl, Class, VBaseOffset);
513  }
514  }
515 
516  // Traverse all member variables.
517  unsigned FieldNo = 0;
518  for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
519  I != E; ++I, ++FieldNo) {
520  if (I->isBitField())
521  continue;
522 
523  CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
524 
525  UpdateEmptyFieldSubobjects(*I, FieldOffset);
526  }
527 }
528 
529 void EmptySubobjectMap::UpdateEmptyFieldSubobjects(const FieldDecl *FD,
530  CharUnits Offset) {
531  QualType T = FD->getType();
532  if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl()) {
533  UpdateEmptyFieldSubobjects(RD, RD, Offset);
534  return;
535  }
536 
537  // If we have an array type we need to update every element.
538  if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) {
539  QualType ElemTy = Context.getBaseElementType(AT);
540  const RecordType *RT = ElemTy->getAs<RecordType>();
541  if (!RT)
542  return;
543 
544  const CXXRecordDecl *RD = RT->getAsCXXRecordDecl();
545  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
546 
547  uint64_t NumElements = Context.getConstantArrayElementCount(AT);
548  CharUnits ElementOffset = Offset;
549 
550  for (uint64_t I = 0; I != NumElements; ++I) {
551  // We know that the only empty subobjects that can conflict with empty
552  // field subobjects are subobjects of empty bases that can be placed at
553  // offset zero. Because of this, we only need to keep track of empty field
554  // subobjects with offsets less than the size of the largest empty
555  // subobject for our class.
556  if (ElementOffset >= SizeOfLargestEmptySubobject)
557  return;
558 
559  UpdateEmptyFieldSubobjects(RD, RD, ElementOffset);
560  ElementOffset += Layout.getSize();
561  }
562  }
563 }
564 
565 typedef llvm::SmallPtrSet<const CXXRecordDecl*, 4> ClassSetTy;
566 
567 class ItaniumRecordLayoutBuilder {
568 protected:
569  // FIXME: Remove this and make the appropriate fields public.
570  friend class clang::ASTContext;
571 
572  const ASTContext &Context;
573 
574  EmptySubobjectMap *EmptySubobjects;
575 
576  /// Size - The current size of the record layout.
577  uint64_t Size;
578 
579  /// Alignment - The current alignment of the record layout.
580  CharUnits Alignment;
581 
582  /// The alignment if attribute packed is not used.
583  CharUnits UnpackedAlignment;
584 
585  /// \brief The maximum of the alignments of top-level members.
586  CharUnits UnadjustedAlignment;
587 
588  SmallVector<uint64_t, 16> FieldOffsets;
589 
590  /// Whether the external AST source has provided a layout for this
591  /// record.
592  unsigned UseExternalLayout : 1;
593 
594  /// Whether we need to infer alignment, even when we have an
595  /// externally-provided layout.
596  unsigned InferAlignment : 1;
597 
598  /// Packed - Whether the record is packed or not.
599  unsigned Packed : 1;
600 
601  unsigned IsUnion : 1;
602 
603  unsigned IsMac68kAlign : 1;
604 
605  unsigned IsMsStruct : 1;
606 
607  /// UnfilledBitsInLastUnit - If the last field laid out was a bitfield,
608  /// this contains the number of bits in the last unit that can be used for
609  /// an adjacent bitfield if necessary. The unit in question is usually
610  /// a byte, but larger units are used if IsMsStruct.
611  unsigned char UnfilledBitsInLastUnit;
612  /// LastBitfieldTypeSize - If IsMsStruct, represents the size of the type
613  /// of the previous field if it was a bitfield.
614  unsigned char LastBitfieldTypeSize;
615 
616  /// MaxFieldAlignment - The maximum allowed field alignment. This is set by
617  /// #pragma pack.
618  CharUnits MaxFieldAlignment;
619 
620  /// DataSize - The data size of the record being laid out.
621  uint64_t DataSize;
622 
623  CharUnits NonVirtualSize;
624  CharUnits NonVirtualAlignment;
625 
626  /// PrimaryBase - the primary base class (if one exists) of the class
627  /// we're laying out.
628  const CXXRecordDecl *PrimaryBase;
629 
630  /// PrimaryBaseIsVirtual - Whether the primary base of the class we're laying
631  /// out is virtual.
632  bool PrimaryBaseIsVirtual;
633 
634  /// HasOwnVFPtr - Whether the class provides its own vtable/vftbl
635  /// pointer, as opposed to inheriting one from a primary base class.
636  bool HasOwnVFPtr;
637 
638  /// the flag of field offset changing due to packed attribute.
639  bool HasPackedField;
640 
641  typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
642 
643  /// Bases - base classes and their offsets in the record.
644  BaseOffsetsMapTy Bases;
645 
646  // VBases - virtual base classes and their offsets in the record.
648 
649  /// IndirectPrimaryBases - Virtual base classes, direct or indirect, that are
650  /// primary base classes for some other direct or indirect base class.
651  CXXIndirectPrimaryBaseSet IndirectPrimaryBases;
652 
653  /// FirstNearlyEmptyVBase - The first nearly empty virtual base class in
654  /// inheritance graph order. Used for determining the primary base class.
655  const CXXRecordDecl *FirstNearlyEmptyVBase;
656 
657  /// VisitedVirtualBases - A set of all the visited virtual bases, used to
658  /// avoid visiting virtual bases more than once.
659  llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBases;
660 
661  /// Valid if UseExternalLayout is true.
662  ExternalLayout External;
663 
664  ItaniumRecordLayoutBuilder(const ASTContext &Context,
665  EmptySubobjectMap *EmptySubobjects)
666  : Context(Context), EmptySubobjects(EmptySubobjects), Size(0),
667  Alignment(CharUnits::One()), UnpackedAlignment(CharUnits::One()),
668  UnadjustedAlignment(CharUnits::One()),
669  UseExternalLayout(false), InferAlignment(false), Packed(false),
670  IsUnion(false), IsMac68kAlign(false), IsMsStruct(false),
671  UnfilledBitsInLastUnit(0), LastBitfieldTypeSize(0),
672  MaxFieldAlignment(CharUnits::Zero()), DataSize(0),
673  NonVirtualSize(CharUnits::Zero()),
674  NonVirtualAlignment(CharUnits::One()), PrimaryBase(nullptr),
675  PrimaryBaseIsVirtual(false), HasOwnVFPtr(false),
676  HasPackedField(false), FirstNearlyEmptyVBase(nullptr) {}
677 
678  void Layout(const RecordDecl *D);
679  void Layout(const CXXRecordDecl *D);
680  void Layout(const ObjCInterfaceDecl *D);
681 
682  void LayoutFields(const RecordDecl *D);
683  void LayoutField(const FieldDecl *D, bool InsertExtraPadding);
684  void LayoutWideBitField(uint64_t FieldSize, uint64_t TypeSize,
685  bool FieldPacked, const FieldDecl *D);
686  void LayoutBitField(const FieldDecl *D);
687 
688  TargetCXXABI getCXXABI() const {
689  return Context.getTargetInfo().getCXXABI();
690  }
691 
692  /// BaseSubobjectInfoAllocator - Allocator for BaseSubobjectInfo objects.
693  llvm::SpecificBumpPtrAllocator<BaseSubobjectInfo> BaseSubobjectInfoAllocator;
694 
695  typedef llvm::DenseMap<const CXXRecordDecl *, BaseSubobjectInfo *>
696  BaseSubobjectInfoMapTy;
697 
698  /// VirtualBaseInfo - Map from all the (direct or indirect) virtual bases
699  /// of the class we're laying out to their base subobject info.
700  BaseSubobjectInfoMapTy VirtualBaseInfo;
701 
702  /// NonVirtualBaseInfo - Map from all the direct non-virtual bases of the
703  /// class we're laying out to their base subobject info.
704  BaseSubobjectInfoMapTy NonVirtualBaseInfo;
705 
706  /// ComputeBaseSubobjectInfo - Compute the base subobject information for the
707  /// bases of the given class.
708  void ComputeBaseSubobjectInfo(const CXXRecordDecl *RD);
709 
710  /// ComputeBaseSubobjectInfo - Compute the base subobject information for a
711  /// single class and all of its base classes.
712  BaseSubobjectInfo *ComputeBaseSubobjectInfo(const CXXRecordDecl *RD,
713  bool IsVirtual,
714  BaseSubobjectInfo *Derived);
715 
716  /// DeterminePrimaryBase - Determine the primary base of the given class.
717  void DeterminePrimaryBase(const CXXRecordDecl *RD);
718 
719  void SelectPrimaryVBase(const CXXRecordDecl *RD);
720 
721  void EnsureVTablePointerAlignment(CharUnits UnpackedBaseAlign);
722 
723  /// LayoutNonVirtualBases - Determines the primary base class (if any) and
724  /// lays it out. Will then proceed to lay out all non-virtual base clasess.
725  void LayoutNonVirtualBases(const CXXRecordDecl *RD);
726 
727  /// LayoutNonVirtualBase - Lays out a single non-virtual base.
728  void LayoutNonVirtualBase(const BaseSubobjectInfo *Base);
729 
730  void AddPrimaryVirtualBaseOffsets(const BaseSubobjectInfo *Info,
731  CharUnits Offset);
732 
733  /// LayoutVirtualBases - Lays out all the virtual bases.
734  void LayoutVirtualBases(const CXXRecordDecl *RD,
735  const CXXRecordDecl *MostDerivedClass);
736 
737  /// LayoutVirtualBase - Lays out a single virtual base.
738  void LayoutVirtualBase(const BaseSubobjectInfo *Base);
739 
740  /// LayoutBase - Will lay out a base and return the offset where it was
741  /// placed, in chars.
742  CharUnits LayoutBase(const BaseSubobjectInfo *Base);
743 
744  /// InitializeLayout - Initialize record layout for the given record decl.
745  void InitializeLayout(const Decl *D);
746 
747  /// FinishLayout - Finalize record layout. Adjust record size based on the
748  /// alignment.
749  void FinishLayout(const NamedDecl *D);
750 
751  void UpdateAlignment(CharUnits NewAlignment, CharUnits UnpackedNewAlignment);
752  void UpdateAlignment(CharUnits NewAlignment) {
753  UpdateAlignment(NewAlignment, NewAlignment);
754  }
755 
756  /// Retrieve the externally-supplied field offset for the given
757  /// field.
758  ///
759  /// \param Field The field whose offset is being queried.
760  /// \param ComputedOffset The offset that we've computed for this field.
761  uint64_t updateExternalFieldOffset(const FieldDecl *Field,
762  uint64_t ComputedOffset);
763 
764  void CheckFieldPadding(uint64_t Offset, uint64_t UnpaddedOffset,
765  uint64_t UnpackedOffset, unsigned UnpackedAlign,
766  bool isPacked, const FieldDecl *D);
767 
768  DiagnosticBuilder Diag(SourceLocation Loc, unsigned DiagID);
769 
770  CharUnits getSize() const {
771  assert(Size % Context.getCharWidth() == 0);
772  return Context.toCharUnitsFromBits(Size);
773  }
774  uint64_t getSizeInBits() const { return Size; }
775 
776  void setSize(CharUnits NewSize) { Size = Context.toBits(NewSize); }
777  void setSize(uint64_t NewSize) { Size = NewSize; }
778 
779  CharUnits getAligment() const { return Alignment; }
780 
781  CharUnits getDataSize() const {
782  assert(DataSize % Context.getCharWidth() == 0);
783  return Context.toCharUnitsFromBits(DataSize);
784  }
785  uint64_t getDataSizeInBits() const { return DataSize; }
786 
787  void setDataSize(CharUnits NewSize) { DataSize = Context.toBits(NewSize); }
788  void setDataSize(uint64_t NewSize) { DataSize = NewSize; }
789 
790  ItaniumRecordLayoutBuilder(const ItaniumRecordLayoutBuilder &) = delete;
791  void operator=(const ItaniumRecordLayoutBuilder &) = delete;
792 };
793 } // end anonymous namespace
794 
795 void ItaniumRecordLayoutBuilder::SelectPrimaryVBase(const CXXRecordDecl *RD) {
796  for (const auto &I : RD->bases()) {
797  assert(!I.getType()->isDependentType() &&
798  "Cannot layout class with dependent bases.");
799 
800  const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();
801 
802  // Check if this is a nearly empty virtual base.
803  if (I.isVirtual() && Context.isNearlyEmpty(Base)) {
804  // If it's not an indirect primary base, then we've found our primary
805  // base.
806  if (!IndirectPrimaryBases.count(Base)) {
807  PrimaryBase = Base;
808  PrimaryBaseIsVirtual = true;
809  return;
810  }
811 
812  // Is this the first nearly empty virtual base?
813  if (!FirstNearlyEmptyVBase)
814  FirstNearlyEmptyVBase = Base;
815  }
816 
817  SelectPrimaryVBase(Base);
818  if (PrimaryBase)
819  return;
820  }
821 }
822 
823 /// DeterminePrimaryBase - Determine the primary base of the given class.
824 void ItaniumRecordLayoutBuilder::DeterminePrimaryBase(const CXXRecordDecl *RD) {
825  // If the class isn't dynamic, it won't have a primary base.
826  if (!RD->isDynamicClass())
827  return;
828 
829  // Compute all the primary virtual bases for all of our direct and
830  // indirect bases, and record all their primary virtual base classes.
831  RD->getIndirectPrimaryBases(IndirectPrimaryBases);
832 
833  // If the record has a dynamic base class, attempt to choose a primary base
834  // class. It is the first (in direct base class order) non-virtual dynamic
835  // base class, if one exists.
836  for (const auto &I : RD->bases()) {
837  // Ignore virtual bases.
838  if (I.isVirtual())
839  continue;
840 
841  const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();
842 
843  if (Base->isDynamicClass()) {
844  // We found it.
845  PrimaryBase = Base;
846  PrimaryBaseIsVirtual = false;
847  return;
848  }
849  }
850 
851  // Under the Itanium ABI, if there is no non-virtual primary base class,
852  // try to compute the primary virtual base. The primary virtual base is
853  // the first nearly empty virtual base that is not an indirect primary
854  // virtual base class, if one exists.
855  if (RD->getNumVBases() != 0) {
856  SelectPrimaryVBase(RD);
857  if (PrimaryBase)
858  return;
859  }
860 
861  // Otherwise, it is the first indirect primary base class, if one exists.
862  if (FirstNearlyEmptyVBase) {
863  PrimaryBase = FirstNearlyEmptyVBase;
864  PrimaryBaseIsVirtual = true;
865  return;
866  }
867 
868  assert(!PrimaryBase && "Should not get here with a primary base!");
869 }
870 
871 BaseSubobjectInfo *ItaniumRecordLayoutBuilder::ComputeBaseSubobjectInfo(
872  const CXXRecordDecl *RD, bool IsVirtual, BaseSubobjectInfo *Derived) {
873  BaseSubobjectInfo *Info;
874 
875  if (IsVirtual) {
876  // Check if we already have info about this virtual base.
877  BaseSubobjectInfo *&InfoSlot = VirtualBaseInfo[RD];
878  if (InfoSlot) {
879  assert(InfoSlot->Class == RD && "Wrong class for virtual base info!");
880  return InfoSlot;
881  }
882 
883  // We don't, create it.
884  InfoSlot = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
885  Info = InfoSlot;
886  } else {
887  Info = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
888  }
889 
890  Info->Class = RD;
891  Info->IsVirtual = IsVirtual;
892  Info->Derived = nullptr;
893  Info->PrimaryVirtualBaseInfo = nullptr;
894 
895  const CXXRecordDecl *PrimaryVirtualBase = nullptr;
896  BaseSubobjectInfo *PrimaryVirtualBaseInfo = nullptr;
897 
898  // Check if this base has a primary virtual base.
899  if (RD->getNumVBases()) {
900  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
901  if (Layout.isPrimaryBaseVirtual()) {
902  // This base does have a primary virtual base.
903  PrimaryVirtualBase = Layout.getPrimaryBase();
904  assert(PrimaryVirtualBase && "Didn't have a primary virtual base!");
905 
906  // Now check if we have base subobject info about this primary base.
907  PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
908 
909  if (PrimaryVirtualBaseInfo) {
910  if (PrimaryVirtualBaseInfo->Derived) {
911  // We did have info about this primary base, and it turns out that it
912  // has already been claimed as a primary virtual base for another
913  // base.
914  PrimaryVirtualBase = nullptr;
915  } else {
916  // We can claim this base as our primary base.
917  Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
918  PrimaryVirtualBaseInfo->Derived = Info;
919  }
920  }
921  }
922  }
923 
924  // Now go through all direct bases.
925  for (const auto &I : RD->bases()) {
926  bool IsVirtual = I.isVirtual();
927 
928  const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
929 
930  Info->Bases.push_back(ComputeBaseSubobjectInfo(BaseDecl, IsVirtual, Info));
931  }
932 
933  if (PrimaryVirtualBase && !PrimaryVirtualBaseInfo) {
934  // Traversing the bases must have created the base info for our primary
935  // virtual base.
936  PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
937  assert(PrimaryVirtualBaseInfo &&
938  "Did not create a primary virtual base!");
939 
940  // Claim the primary virtual base as our primary virtual base.
941  Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
942  PrimaryVirtualBaseInfo->Derived = Info;
943  }
944 
945  return Info;
946 }
947 
948 void ItaniumRecordLayoutBuilder::ComputeBaseSubobjectInfo(
949  const CXXRecordDecl *RD) {
950  for (const auto &I : RD->bases()) {
951  bool IsVirtual = I.isVirtual();
952 
953  const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
954 
955  // Compute the base subobject info for this base.
956  BaseSubobjectInfo *Info = ComputeBaseSubobjectInfo(BaseDecl, IsVirtual,
957  nullptr);
958 
959  if (IsVirtual) {
960  // ComputeBaseInfo has already added this base for us.
961  assert(VirtualBaseInfo.count(BaseDecl) &&
962  "Did not add virtual base!");
963  } else {
964  // Add the base info to the map of non-virtual bases.
965  assert(!NonVirtualBaseInfo.count(BaseDecl) &&
966  "Non-virtual base already exists!");
967  NonVirtualBaseInfo.insert(std::make_pair(BaseDecl, Info));
968  }
969  }
970 }
971 
972 void ItaniumRecordLayoutBuilder::EnsureVTablePointerAlignment(
973  CharUnits UnpackedBaseAlign) {
974  CharUnits BaseAlign = Packed ? CharUnits::One() : UnpackedBaseAlign;
975 
976  // The maximum field alignment overrides base align.
977  if (!MaxFieldAlignment.isZero()) {
978  BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
979  UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
980  }
981 
982  // Round up the current record size to pointer alignment.
983  setSize(getSize().alignTo(BaseAlign));
984  setDataSize(getSize());
985 
986  // Update the alignment.
987  UpdateAlignment(BaseAlign, UnpackedBaseAlign);
988 }
989 
990 void ItaniumRecordLayoutBuilder::LayoutNonVirtualBases(
991  const CXXRecordDecl *RD) {
992  // Then, determine the primary base class.
993  DeterminePrimaryBase(RD);
994 
995  // Compute base subobject info.
996  ComputeBaseSubobjectInfo(RD);
997 
998  // If we have a primary base class, lay it out.
999  if (PrimaryBase) {
1000  if (PrimaryBaseIsVirtual) {
1001  // If the primary virtual base was a primary virtual base of some other
1002  // base class we'll have to steal it.
1003  BaseSubobjectInfo *PrimaryBaseInfo = VirtualBaseInfo.lookup(PrimaryBase);
1004  PrimaryBaseInfo->Derived = nullptr;
1005 
1006  // We have a virtual primary base, insert it as an indirect primary base.
1007  IndirectPrimaryBases.insert(PrimaryBase);
1008 
1009  assert(!VisitedVirtualBases.count(PrimaryBase) &&
1010  "vbase already visited!");
1011  VisitedVirtualBases.insert(PrimaryBase);
1012 
1013  LayoutVirtualBase(PrimaryBaseInfo);
1014  } else {
1015  BaseSubobjectInfo *PrimaryBaseInfo =
1016  NonVirtualBaseInfo.lookup(PrimaryBase);
1017  assert(PrimaryBaseInfo &&
1018  "Did not find base info for non-virtual primary base!");
1019 
1020  LayoutNonVirtualBase(PrimaryBaseInfo);
1021  }
1022 
1023  // If this class needs a vtable/vf-table and didn't get one from a
1024  // primary base, add it in now.
1025  } else if (RD->isDynamicClass()) {
1026  assert(DataSize == 0 && "Vtable pointer must be at offset zero!");
1027  CharUnits PtrWidth =
1028  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
1029  CharUnits PtrAlign =
1030  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
1031  EnsureVTablePointerAlignment(PtrAlign);
1032  HasOwnVFPtr = true;
1033  setSize(getSize() + PtrWidth);
1034  setDataSize(getSize());
1035  }
1036 
1037  // Now lay out the non-virtual bases.
1038  for (const auto &I : RD->bases()) {
1039 
1040  // Ignore virtual bases.
1041  if (I.isVirtual())
1042  continue;
1043 
1044  const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
1045 
1046  // Skip the primary base, because we've already laid it out. The
1047  // !PrimaryBaseIsVirtual check is required because we might have a
1048  // non-virtual base of the same type as a primary virtual base.
1049  if (BaseDecl == PrimaryBase && !PrimaryBaseIsVirtual)
1050  continue;
1051 
1052  // Lay out the base.
1053  BaseSubobjectInfo *BaseInfo = NonVirtualBaseInfo.lookup(BaseDecl);
1054  assert(BaseInfo && "Did not find base info for non-virtual base!");
1055 
1056  LayoutNonVirtualBase(BaseInfo);
1057  }
1058 }
1059 
1060 void ItaniumRecordLayoutBuilder::LayoutNonVirtualBase(
1061  const BaseSubobjectInfo *Base) {
1062  // Layout the base.
1063  CharUnits Offset = LayoutBase(Base);
1064 
1065  // Add its base class offset.
1066  assert(!Bases.count(Base->Class) && "base offset already exists!");
1067  Bases.insert(std::make_pair(Base->Class, Offset));
1068 
1069  AddPrimaryVirtualBaseOffsets(Base, Offset);
1070 }
1071 
1072 void ItaniumRecordLayoutBuilder::AddPrimaryVirtualBaseOffsets(
1073  const BaseSubobjectInfo *Info, CharUnits Offset) {
1074  // This base isn't interesting, it has no virtual bases.
1075  if (!Info->Class->getNumVBases())
1076  return;
1077 
1078  // First, check if we have a virtual primary base to add offsets for.
1079  if (Info->PrimaryVirtualBaseInfo) {
1080  assert(Info->PrimaryVirtualBaseInfo->IsVirtual &&
1081  "Primary virtual base is not virtual!");
1082  if (Info->PrimaryVirtualBaseInfo->Derived == Info) {
1083  // Add the offset.
1084  assert(!VBases.count(Info->PrimaryVirtualBaseInfo->Class) &&
1085  "primary vbase offset already exists!");
1086  VBases.insert(std::make_pair(Info->PrimaryVirtualBaseInfo->Class,
1087  ASTRecordLayout::VBaseInfo(Offset, false)));
1088 
1089  // Traverse the primary virtual base.
1090  AddPrimaryVirtualBaseOffsets(Info->PrimaryVirtualBaseInfo, Offset);
1091  }
1092  }
1093 
1094  // Now go through all direct non-virtual bases.
1095  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
1096  for (const BaseSubobjectInfo *Base : Info->Bases) {
1097  if (Base->IsVirtual)
1098  continue;
1099 
1100  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
1101  AddPrimaryVirtualBaseOffsets(Base, BaseOffset);
1102  }
1103 }
1104 
1105 void ItaniumRecordLayoutBuilder::LayoutVirtualBases(
1106  const CXXRecordDecl *RD, const CXXRecordDecl *MostDerivedClass) {
1107  const CXXRecordDecl *PrimaryBase;
1108  bool PrimaryBaseIsVirtual;
1109 
1110  if (MostDerivedClass == RD) {
1111  PrimaryBase = this->PrimaryBase;
1112  PrimaryBaseIsVirtual = this->PrimaryBaseIsVirtual;
1113  } else {
1114  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1115  PrimaryBase = Layout.getPrimaryBase();
1116  PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual();
1117  }
1118 
1119  for (const CXXBaseSpecifier &Base : RD->bases()) {
1120  assert(!Base.getType()->isDependentType() &&
1121  "Cannot layout class with dependent bases.");
1122 
1123  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1124 
1125  if (Base.isVirtual()) {
1126  if (PrimaryBase != BaseDecl || !PrimaryBaseIsVirtual) {
1127  bool IndirectPrimaryBase = IndirectPrimaryBases.count(BaseDecl);
1128 
1129  // Only lay out the virtual base if it's not an indirect primary base.
1130  if (!IndirectPrimaryBase) {
1131  // Only visit virtual bases once.
1132  if (!VisitedVirtualBases.insert(BaseDecl).second)
1133  continue;
1134 
1135  const BaseSubobjectInfo *BaseInfo = VirtualBaseInfo.lookup(BaseDecl);
1136  assert(BaseInfo && "Did not find virtual base info!");
1137  LayoutVirtualBase(BaseInfo);
1138  }
1139  }
1140  }
1141 
1142  if (!BaseDecl->getNumVBases()) {
1143  // This base isn't interesting since it doesn't have any virtual bases.
1144  continue;
1145  }
1146 
1147  LayoutVirtualBases(BaseDecl, MostDerivedClass);
1148  }
1149 }
1150 
1151 void ItaniumRecordLayoutBuilder::LayoutVirtualBase(
1152  const BaseSubobjectInfo *Base) {
1153  assert(!Base->Derived && "Trying to lay out a primary virtual base!");
1154 
1155  // Layout the base.
1156  CharUnits Offset = LayoutBase(Base);
1157 
1158  // Add its base class offset.
1159  assert(!VBases.count(Base->Class) && "vbase offset already exists!");
1160  VBases.insert(std::make_pair(Base->Class,
1161  ASTRecordLayout::VBaseInfo(Offset, false)));
1162 
1163  AddPrimaryVirtualBaseOffsets(Base, Offset);
1164 }
1165 
1166 CharUnits
1167 ItaniumRecordLayoutBuilder::LayoutBase(const BaseSubobjectInfo *Base) {
1168  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base->Class);
1169 
1170 
1171  CharUnits Offset;
1172 
1173  // Query the external layout to see if it provides an offset.
1174  bool HasExternalLayout = false;
1175  if (UseExternalLayout) {
1176  if (Base->IsVirtual)
1177  HasExternalLayout = External.getExternalNVBaseOffset(Base->Class, Offset);
1178  else
1179  HasExternalLayout = External.getExternalVBaseOffset(Base->Class, Offset);
1180  }
1181 
1182  // Clang <= 6 incorrectly applied the 'packed' attribute to base classes.
1183  // Per GCC's documentation, it only applies to non-static data members.
1184  CharUnits UnpackedBaseAlign = Layout.getNonVirtualAlignment();
1185  CharUnits BaseAlign =
1186  (Packed && ((Context.getLangOpts().getClangABICompat() <=
1188  Context.getTargetInfo().getTriple().isPS4()))
1189  ? CharUnits::One()
1190  : UnpackedBaseAlign;
1191 
1192  // If we have an empty base class, try to place it at offset 0.
1193  if (Base->Class->isEmpty() &&
1194  (!HasExternalLayout || Offset == CharUnits::Zero()) &&
1195  EmptySubobjects->CanPlaceBaseAtOffset(Base, CharUnits::Zero())) {
1196  setSize(std::max(getSize(), Layout.getSize()));
1197  UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1198 
1199  return CharUnits::Zero();
1200  }
1201 
1202  // The maximum field alignment overrides base align.
1203  if (!MaxFieldAlignment.isZero()) {
1204  BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
1205  UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
1206  }
1207 
1208  if (!HasExternalLayout) {
1209  // Round up the current record size to the base's alignment boundary.
1210  Offset = getDataSize().alignTo(BaseAlign);
1211 
1212  // Try to place the base.
1213  while (!EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset))
1214  Offset += BaseAlign;
1215  } else {
1216  bool Allowed = EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset);
1217  (void)Allowed;
1218  assert(Allowed && "Base subobject externally placed at overlapping offset");
1219 
1220  if (InferAlignment && Offset < getDataSize().alignTo(BaseAlign)) {
1221  // The externally-supplied base offset is before the base offset we
1222  // computed. Assume that the structure is packed.
1223  Alignment = CharUnits::One();
1224  InferAlignment = false;
1225  }
1226  }
1227 
1228  if (!Base->Class->isEmpty()) {
1229  // Update the data size.
1230  setDataSize(Offset + Layout.getNonVirtualSize());
1231 
1232  setSize(std::max(getSize(), getDataSize()));
1233  } else
1234  setSize(std::max(getSize(), Offset + Layout.getSize()));
1235 
1236  // Remember max struct/class alignment.
1237  UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1238 
1239  return Offset;
1240 }
1241 
1242 void ItaniumRecordLayoutBuilder::InitializeLayout(const Decl *D) {
1243  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
1244  IsUnion = RD->isUnion();
1245  IsMsStruct = RD->isMsStruct(Context);
1246  }
1247 
1248  Packed = D->hasAttr<PackedAttr>();
1249 
1250  // Honor the default struct packing maximum alignment flag.
1251  if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct) {
1252  MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
1253  }
1254 
1255  // mac68k alignment supersedes maximum field alignment and attribute aligned,
1256  // and forces all structures to have 2-byte alignment. The IBM docs on it
1257  // allude to additional (more complicated) semantics, especially with regard
1258  // to bit-fields, but gcc appears not to follow that.
1259  if (D->hasAttr<AlignMac68kAttr>()) {
1260  IsMac68kAlign = true;
1261  MaxFieldAlignment = CharUnits::fromQuantity(2);
1262  Alignment = CharUnits::fromQuantity(2);
1263  } else {
1264  if (const MaxFieldAlignmentAttr *MFAA = D->getAttr<MaxFieldAlignmentAttr>())
1265  MaxFieldAlignment = Context.toCharUnitsFromBits(MFAA->getAlignment());
1266 
1267  if (unsigned MaxAlign = D->getMaxAlignment())
1268  UpdateAlignment(Context.toCharUnitsFromBits(MaxAlign));
1269  }
1270 
1271  // If there is an external AST source, ask it for the various offsets.
1272  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D))
1273  if (ExternalASTSource *Source = Context.getExternalSource()) {
1274  UseExternalLayout = Source->layoutRecordType(
1275  RD, External.Size, External.Align, External.FieldOffsets,
1276  External.BaseOffsets, External.VirtualBaseOffsets);
1277 
1278  // Update based on external alignment.
1279  if (UseExternalLayout) {
1280  if (External.Align > 0) {
1281  Alignment = Context.toCharUnitsFromBits(External.Align);
1282  } else {
1283  // The external source didn't have alignment information; infer it.
1284  InferAlignment = true;
1285  }
1286  }
1287  }
1288 }
1289 
1290 void ItaniumRecordLayoutBuilder::Layout(const RecordDecl *D) {
1291  InitializeLayout(D);
1292  LayoutFields(D);
1293 
1294  // Finally, round the size of the total struct up to the alignment of the
1295  // struct itself.
1296  FinishLayout(D);
1297 }
1298 
1299 void ItaniumRecordLayoutBuilder::Layout(const CXXRecordDecl *RD) {
1300  InitializeLayout(RD);
1301 
1302  // Lay out the vtable and the non-virtual bases.
1303  LayoutNonVirtualBases(RD);
1304 
1305  LayoutFields(RD);
1306 
1307  NonVirtualSize = Context.toCharUnitsFromBits(
1308  llvm::alignTo(getSizeInBits(), Context.getTargetInfo().getCharAlign()));
1309  NonVirtualAlignment = Alignment;
1310 
1311  // Lay out the virtual bases and add the primary virtual base offsets.
1312  LayoutVirtualBases(RD, RD);
1313 
1314  // Finally, round the size of the total struct up to the alignment
1315  // of the struct itself.
1316  FinishLayout(RD);
1317 
1318 #ifndef NDEBUG
1319  // Check that we have base offsets for all bases.
1320  for (const CXXBaseSpecifier &Base : RD->bases()) {
1321  if (Base.isVirtual())
1322  continue;
1323 
1324  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1325 
1326  assert(Bases.count(BaseDecl) && "Did not find base offset!");
1327  }
1328 
1329  // And all virtual bases.
1330  for (const CXXBaseSpecifier &Base : RD->vbases()) {
1331  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1332 
1333  assert(VBases.count(BaseDecl) && "Did not find base offset!");
1334  }
1335 #endif
1336 }
1337 
1338 void ItaniumRecordLayoutBuilder::Layout(const ObjCInterfaceDecl *D) {
1339  if (ObjCInterfaceDecl *SD = D->getSuperClass()) {
1340  const ASTRecordLayout &SL = Context.getASTObjCInterfaceLayout(SD);
1341 
1342  UpdateAlignment(SL.getAlignment());
1343 
1344  // We start laying out ivars not at the end of the superclass
1345  // structure, but at the next byte following the last field.
1346  setSize(SL.getDataSize());
1347  setDataSize(getSize());
1348  }
1349 
1350  InitializeLayout(D);
1351  // Layout each ivar sequentially.
1352  for (const ObjCIvarDecl *IVD = D->all_declared_ivar_begin(); IVD;
1353  IVD = IVD->getNextIvar())
1354  LayoutField(IVD, false);
1355 
1356  // Finally, round the size of the total struct up to the alignment of the
1357  // struct itself.
1358  FinishLayout(D);
1359 }
1360 
1361 void ItaniumRecordLayoutBuilder::LayoutFields(const RecordDecl *D) {
1362  // Layout each field, for now, just sequentially, respecting alignment. In
1363  // the future, this will need to be tweakable by targets.
1364  bool InsertExtraPadding = D->mayInsertExtraPadding(/*EmitRemark=*/true);
1365  bool HasFlexibleArrayMember = D->hasFlexibleArrayMember();
1366  for (auto I = D->field_begin(), End = D->field_end(); I != End; ++I) {
1367  auto Next(I);
1368  ++Next;
1369  LayoutField(*I,
1370  InsertExtraPadding && (Next != End || !HasFlexibleArrayMember));
1371  }
1372 }
1373 
1374 // Rounds the specified size to have it a multiple of the char size.
1375 static uint64_t
1377  const ASTContext &Context) {
1378  uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
1379  return llvm::alignTo(Size, CharAlignment);
1380 }
1381 
1382 void ItaniumRecordLayoutBuilder::LayoutWideBitField(uint64_t FieldSize,
1383  uint64_t TypeSize,
1384  bool FieldPacked,
1385  const FieldDecl *D) {
1386  assert(Context.getLangOpts().CPlusPlus &&
1387  "Can only have wide bit-fields in C++!");
1388 
1389  // Itanium C++ ABI 2.4:
1390  // If sizeof(T)*8 < n, let T' be the largest integral POD type with
1391  // sizeof(T')*8 <= n.
1392 
1393  QualType IntegralPODTypes[] = {
1394  Context.UnsignedCharTy, Context.UnsignedShortTy, Context.UnsignedIntTy,
1395  Context.UnsignedLongTy, Context.UnsignedLongLongTy
1396  };
1397 
1398  QualType Type;
1399  for (const QualType &QT : IntegralPODTypes) {
1400  uint64_t Size = Context.getTypeSize(QT);
1401 
1402  if (Size > FieldSize)
1403  break;
1404 
1405  Type = QT;
1406  }
1407  assert(!Type.isNull() && "Did not find a type!");
1408 
1409  CharUnits TypeAlign = Context.getTypeAlignInChars(Type);
1410 
1411  // We're not going to use any of the unfilled bits in the last byte.
1412  UnfilledBitsInLastUnit = 0;
1413  LastBitfieldTypeSize = 0;
1414 
1415  uint64_t FieldOffset;
1416  uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
1417 
1418  if (IsUnion) {
1419  uint64_t RoundedFieldSize = roundUpSizeToCharAlignment(FieldSize,
1420  Context);
1421  setDataSize(std::max(getDataSizeInBits(), RoundedFieldSize));
1422  FieldOffset = 0;
1423  } else {
1424  // The bitfield is allocated starting at the next offset aligned
1425  // appropriately for T', with length n bits.
1426  FieldOffset = llvm::alignTo(getDataSizeInBits(), Context.toBits(TypeAlign));
1427 
1428  uint64_t NewSizeInBits = FieldOffset + FieldSize;
1429 
1430  setDataSize(
1431  llvm::alignTo(NewSizeInBits, Context.getTargetInfo().getCharAlign()));
1432  UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;
1433  }
1434 
1435  // Place this field at the current location.
1436  FieldOffsets.push_back(FieldOffset);
1437 
1438  CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, FieldOffset,
1439  Context.toBits(TypeAlign), FieldPacked, D);
1440 
1441  // Update the size.
1442  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1443 
1444  // Remember max struct/class alignment.
1445  UpdateAlignment(TypeAlign);
1446 }
1447 
1448 void ItaniumRecordLayoutBuilder::LayoutBitField(const FieldDecl *D) {
1449  bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
1450  uint64_t FieldSize = D->getBitWidthValue(Context);
1451  TypeInfo FieldInfo = Context.getTypeInfo(D->getType());
1452  uint64_t TypeSize = FieldInfo.Width;
1453  unsigned FieldAlign = FieldInfo.Align;
1454 
1455  // UnfilledBitsInLastUnit is the difference between the end of the
1456  // last allocated bitfield (i.e. the first bit offset available for
1457  // bitfields) and the end of the current data size in bits (i.e. the
1458  // first bit offset available for non-bitfields). The current data
1459  // size in bits is always a multiple of the char size; additionally,
1460  // for ms_struct records it's also a multiple of the
1461  // LastBitfieldTypeSize (if set).
1462 
1463  // The struct-layout algorithm is dictated by the platform ABI,
1464  // which in principle could use almost any rules it likes. In
1465  // practice, UNIXy targets tend to inherit the algorithm described
1466  // in the System V generic ABI. The basic bitfield layout rule in
1467  // System V is to place bitfields at the next available bit offset
1468  // where the entire bitfield would fit in an aligned storage unit of
1469  // the declared type; it's okay if an earlier or later non-bitfield
1470  // is allocated in the same storage unit. However, some targets
1471  // (those that !useBitFieldTypeAlignment(), e.g. ARM APCS) don't
1472  // require this storage unit to be aligned, and therefore always put
1473  // the bitfield at the next available bit offset.
1474 
1475  // ms_struct basically requests a complete replacement of the
1476  // platform ABI's struct-layout algorithm, with the high-level goal
1477  // of duplicating MSVC's layout. For non-bitfields, this follows
1478  // the standard algorithm. The basic bitfield layout rule is to
1479  // allocate an entire unit of the bitfield's declared type
1480  // (e.g. 'unsigned long'), then parcel it up among successive
1481  // bitfields whose declared types have the same size, making a new
1482  // unit as soon as the last can no longer store the whole value.
1483  // Since it completely replaces the platform ABI's algorithm,
1484  // settings like !useBitFieldTypeAlignment() do not apply.
1485 
1486  // A zero-width bitfield forces the use of a new storage unit for
1487  // later bitfields. In general, this occurs by rounding up the
1488  // current size of the struct as if the algorithm were about to
1489  // place a non-bitfield of the field's formal type. Usually this
1490  // does not change the alignment of the struct itself, but it does
1491  // on some targets (those that useZeroLengthBitfieldAlignment(),
1492  // e.g. ARM). In ms_struct layout, zero-width bitfields are
1493  // ignored unless they follow a non-zero-width bitfield.
1494 
1495  // A field alignment restriction (e.g. from #pragma pack) or
1496  // specification (e.g. from __attribute__((aligned))) changes the
1497  // formal alignment of the field. For System V, this alters the
1498  // required alignment of the notional storage unit that must contain
1499  // the bitfield. For ms_struct, this only affects the placement of
1500  // new storage units. In both cases, the effect of #pragma pack is
1501  // ignored on zero-width bitfields.
1502 
1503  // On System V, a packed field (e.g. from #pragma pack or
1504  // __attribute__((packed))) always uses the next available bit
1505  // offset.
1506 
1507  // In an ms_struct struct, the alignment of a fundamental type is
1508  // always equal to its size. This is necessary in order to mimic
1509  // the i386 alignment rules on targets which might not fully align
1510  // all types (e.g. Darwin PPC32, where alignof(long long) == 4).
1511 
1512  // First, some simple bookkeeping to perform for ms_struct structs.
1513  if (IsMsStruct) {
1514  // The field alignment for integer types is always the size.
1515  FieldAlign = TypeSize;
1516 
1517  // If the previous field was not a bitfield, or was a bitfield
1518  // with a different storage unit size, or if this field doesn't fit into
1519  // the current storage unit, we're done with that storage unit.
1520  if (LastBitfieldTypeSize != TypeSize ||
1521  UnfilledBitsInLastUnit < FieldSize) {
1522  // Also, ignore zero-length bitfields after non-bitfields.
1523  if (!LastBitfieldTypeSize && !FieldSize)
1524  FieldAlign = 1;
1525 
1526  UnfilledBitsInLastUnit = 0;
1527  LastBitfieldTypeSize = 0;
1528  }
1529  }
1530 
1531  // If the field is wider than its declared type, it follows
1532  // different rules in all cases.
1533  if (FieldSize > TypeSize) {
1534  LayoutWideBitField(FieldSize, TypeSize, FieldPacked, D);
1535  return;
1536  }
1537 
1538  // Compute the next available bit offset.
1539  uint64_t FieldOffset =
1540  IsUnion ? 0 : (getDataSizeInBits() - UnfilledBitsInLastUnit);
1541 
1542  // Handle targets that don't honor bitfield type alignment.
1543  if (!IsMsStruct && !Context.getTargetInfo().useBitFieldTypeAlignment()) {
1544  // Some such targets do honor it on zero-width bitfields.
1545  if (FieldSize == 0 &&
1547  // The alignment to round up to is the max of the field's natural
1548  // alignment and a target-specific fixed value (sometimes zero).
1549  unsigned ZeroLengthBitfieldBoundary =
1551  FieldAlign = std::max(FieldAlign, ZeroLengthBitfieldBoundary);
1552 
1553  // If that doesn't apply, just ignore the field alignment.
1554  } else {
1555  FieldAlign = 1;
1556  }
1557  }
1558 
1559  // Remember the alignment we would have used if the field were not packed.
1560  unsigned UnpackedFieldAlign = FieldAlign;
1561 
1562  // Ignore the field alignment if the field is packed unless it has zero-size.
1563  if (!IsMsStruct && FieldPacked && FieldSize != 0)
1564  FieldAlign = 1;
1565 
1566  // But, if there's an 'aligned' attribute on the field, honor that.
1567  unsigned ExplicitFieldAlign = D->getMaxAlignment();
1568  if (ExplicitFieldAlign) {
1569  FieldAlign = std::max(FieldAlign, ExplicitFieldAlign);
1570  UnpackedFieldAlign = std::max(UnpackedFieldAlign, ExplicitFieldAlign);
1571  }
1572 
1573  // But, if there's a #pragma pack in play, that takes precedent over
1574  // even the 'aligned' attribute, for non-zero-width bitfields.
1575  unsigned MaxFieldAlignmentInBits = Context.toBits(MaxFieldAlignment);
1576  if (!MaxFieldAlignment.isZero() && FieldSize) {
1577  UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignmentInBits);
1578  if (FieldPacked)
1579  FieldAlign = UnpackedFieldAlign;
1580  else
1581  FieldAlign = std::min(FieldAlign, MaxFieldAlignmentInBits);
1582  }
1583 
1584  // But, ms_struct just ignores all of that in unions, even explicit
1585  // alignment attributes.
1586  if (IsMsStruct && IsUnion) {
1587  FieldAlign = UnpackedFieldAlign = 1;
1588  }
1589 
1590  // For purposes of diagnostics, we're going to simultaneously
1591  // compute the field offsets that we would have used if we weren't
1592  // adding any alignment padding or if the field weren't packed.
1593  uint64_t UnpaddedFieldOffset = FieldOffset;
1594  uint64_t UnpackedFieldOffset = FieldOffset;
1595 
1596  // Check if we need to add padding to fit the bitfield within an
1597  // allocation unit with the right size and alignment. The rules are
1598  // somewhat different here for ms_struct structs.
1599  if (IsMsStruct) {
1600  // If it's not a zero-width bitfield, and we can fit the bitfield
1601  // into the active storage unit (and we haven't already decided to
1602  // start a new storage unit), just do so, regardless of any other
1603  // other consideration. Otherwise, round up to the right alignment.
1604  if (FieldSize == 0 || FieldSize > UnfilledBitsInLastUnit) {
1605  FieldOffset = llvm::alignTo(FieldOffset, FieldAlign);
1606  UnpackedFieldOffset =
1607  llvm::alignTo(UnpackedFieldOffset, UnpackedFieldAlign);
1608  UnfilledBitsInLastUnit = 0;
1609  }
1610 
1611  } else {
1612  // #pragma pack, with any value, suppresses the insertion of padding.
1613  bool AllowPadding = MaxFieldAlignment.isZero();
1614 
1615  // Compute the real offset.
1616  if (FieldSize == 0 ||
1617  (AllowPadding &&
1618  (FieldOffset & (FieldAlign-1)) + FieldSize > TypeSize)) {
1619  FieldOffset = llvm::alignTo(FieldOffset, FieldAlign);
1620  } else if (ExplicitFieldAlign &&
1621  (MaxFieldAlignmentInBits == 0 ||
1622  ExplicitFieldAlign <= MaxFieldAlignmentInBits) &&
1624  // TODO: figure it out what needs to be done on targets that don't honor
1625  // bit-field type alignment like ARM APCS ABI.
1626  FieldOffset = llvm::alignTo(FieldOffset, ExplicitFieldAlign);
1627  }
1628 
1629  // Repeat the computation for diagnostic purposes.
1630  if (FieldSize == 0 ||
1631  (AllowPadding &&
1632  (UnpackedFieldOffset & (UnpackedFieldAlign-1)) + FieldSize > TypeSize))
1633  UnpackedFieldOffset =
1634  llvm::alignTo(UnpackedFieldOffset, UnpackedFieldAlign);
1635  else if (ExplicitFieldAlign &&
1636  (MaxFieldAlignmentInBits == 0 ||
1637  ExplicitFieldAlign <= MaxFieldAlignmentInBits) &&
1639  UnpackedFieldOffset =
1640  llvm::alignTo(UnpackedFieldOffset, ExplicitFieldAlign);
1641  }
1642 
1643  // If we're using external layout, give the external layout a chance
1644  // to override this information.
1645  if (UseExternalLayout)
1646  FieldOffset = updateExternalFieldOffset(D, FieldOffset);
1647 
1648  // Okay, place the bitfield at the calculated offset.
1649  FieldOffsets.push_back(FieldOffset);
1650 
1651  // Bookkeeping:
1652 
1653  // Anonymous members don't affect the overall record alignment,
1654  // except on targets where they do.
1655  if (!IsMsStruct &&
1657  !D->getIdentifier())
1658  FieldAlign = UnpackedFieldAlign = 1;
1659 
1660  // Diagnose differences in layout due to padding or packing.
1661  if (!UseExternalLayout)
1662  CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, UnpackedFieldOffset,
1663  UnpackedFieldAlign, FieldPacked, D);
1664 
1665  // Update DataSize to include the last byte containing (part of) the bitfield.
1666 
1667  // For unions, this is just a max operation, as usual.
1668  if (IsUnion) {
1669  // For ms_struct, allocate the entire storage unit --- unless this
1670  // is a zero-width bitfield, in which case just use a size of 1.
1671  uint64_t RoundedFieldSize;
1672  if (IsMsStruct) {
1673  RoundedFieldSize =
1674  (FieldSize ? TypeSize : Context.getTargetInfo().getCharWidth());
1675 
1676  // Otherwise, allocate just the number of bytes required to store
1677  // the bitfield.
1678  } else {
1679  RoundedFieldSize = roundUpSizeToCharAlignment(FieldSize, Context);
1680  }
1681  setDataSize(std::max(getDataSizeInBits(), RoundedFieldSize));
1682 
1683  // For non-zero-width bitfields in ms_struct structs, allocate a new
1684  // storage unit if necessary.
1685  } else if (IsMsStruct && FieldSize) {
1686  // We should have cleared UnfilledBitsInLastUnit in every case
1687  // where we changed storage units.
1688  if (!UnfilledBitsInLastUnit) {
1689  setDataSize(FieldOffset + TypeSize);
1690  UnfilledBitsInLastUnit = TypeSize;
1691  }
1692  UnfilledBitsInLastUnit -= FieldSize;
1693  LastBitfieldTypeSize = TypeSize;
1694 
1695  // Otherwise, bump the data size up to include the bitfield,
1696  // including padding up to char alignment, and then remember how
1697  // bits we didn't use.
1698  } else {
1699  uint64_t NewSizeInBits = FieldOffset + FieldSize;
1700  uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
1701  setDataSize(llvm::alignTo(NewSizeInBits, CharAlignment));
1702  UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;
1703 
1704  // The only time we can get here for an ms_struct is if this is a
1705  // zero-width bitfield, which doesn't count as anything for the
1706  // purposes of unfilled bits.
1707  LastBitfieldTypeSize = 0;
1708  }
1709 
1710  // Update the size.
1711  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1712 
1713  // Remember max struct/class alignment.
1714  UnadjustedAlignment =
1715  std::max(UnadjustedAlignment, Context.toCharUnitsFromBits(FieldAlign));
1716  UpdateAlignment(Context.toCharUnitsFromBits(FieldAlign),
1717  Context.toCharUnitsFromBits(UnpackedFieldAlign));
1718 }
1719 
1720 void ItaniumRecordLayoutBuilder::LayoutField(const FieldDecl *D,
1721  bool InsertExtraPadding) {
1722  if (D->isBitField()) {
1723  LayoutBitField(D);
1724  return;
1725  }
1726 
1727  uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
1728 
1729  // Reset the unfilled bits.
1730  UnfilledBitsInLastUnit = 0;
1731  LastBitfieldTypeSize = 0;
1732 
1733  bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
1734  CharUnits FieldOffset =
1735  IsUnion ? CharUnits::Zero() : getDataSize();
1736  CharUnits FieldSize;
1737  CharUnits FieldAlign;
1738 
1739  if (D->getType()->isIncompleteArrayType()) {
1740  // This is a flexible array member; we can't directly
1741  // query getTypeInfo about these, so we figure it out here.
1742  // Flexible array members don't have any size, but they
1743  // have to be aligned appropriately for their element type.
1744  FieldSize = CharUnits::Zero();
1745  const ArrayType* ATy = Context.getAsArrayType(D->getType());
1746  FieldAlign = Context.getTypeAlignInChars(ATy->getElementType());
1747  } else if (const ReferenceType *RT = D->getType()->getAs<ReferenceType>()) {
1748  unsigned AS = Context.getTargetAddressSpace(RT->getPointeeType());
1749  FieldSize =
1750  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(AS));
1751  FieldAlign =
1752  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(AS));
1753  } else {
1754  std::pair<CharUnits, CharUnits> FieldInfo =
1755  Context.getTypeInfoInChars(D->getType());
1756  FieldSize = FieldInfo.first;
1757  FieldAlign = FieldInfo.second;
1758 
1759  if (IsMsStruct) {
1760  // If MS bitfield layout is required, figure out what type is being
1761  // laid out and align the field to the width of that type.
1762 
1763  // Resolve all typedefs down to their base type and round up the field
1764  // alignment if necessary.
1765  QualType T = Context.getBaseElementType(D->getType());
1766  if (const BuiltinType *BTy = T->getAs<BuiltinType>()) {
1767  CharUnits TypeSize = Context.getTypeSizeInChars(BTy);
1768 
1769  if (!llvm::isPowerOf2_64(TypeSize.getQuantity())) {
1770  assert(
1771  !Context.getTargetInfo().getTriple().isWindowsMSVCEnvironment() &&
1772  "Non PowerOf2 size in MSVC mode");
1773  // Base types with sizes that aren't a power of two don't work
1774  // with the layout rules for MS structs. This isn't an issue in
1775  // MSVC itself since there are no such base data types there.
1776  // On e.g. x86_32 mingw and linux, long double is 12 bytes though.
1777  // Any structs involving that data type obviously can't be ABI
1778  // compatible with MSVC regardless of how it is laid out.
1779 
1780  // Since ms_struct can be mass enabled (via a pragma or via the
1781  // -mms-bitfields command line parameter), this can trigger for
1782  // structs that don't actually need MSVC compatibility, so we
1783  // need to be able to sidestep the ms_struct layout for these types.
1784 
1785  // Since the combination of -mms-bitfields together with structs
1786  // like max_align_t (which contains a long double) for mingw is
1787  // quite comon (and GCC handles it silently), just handle it
1788  // silently there. For other targets that have ms_struct enabled
1789  // (most probably via a pragma or attribute), trigger a diagnostic
1790  // that defaults to an error.
1791  if (!Context.getTargetInfo().getTriple().isWindowsGNUEnvironment())
1792  Diag(D->getLocation(), diag::warn_npot_ms_struct);
1793  }
1794  if (TypeSize > FieldAlign &&
1795  llvm::isPowerOf2_64(TypeSize.getQuantity()))
1796  FieldAlign = TypeSize;
1797  }
1798  }
1799  }
1800 
1801  // The align if the field is not packed. This is to check if the attribute
1802  // was unnecessary (-Wpacked).
1803  CharUnits UnpackedFieldAlign = FieldAlign;
1804  CharUnits UnpackedFieldOffset = FieldOffset;
1805 
1806  if (FieldPacked)
1807  FieldAlign = CharUnits::One();
1808  CharUnits MaxAlignmentInChars =
1809  Context.toCharUnitsFromBits(D->getMaxAlignment());
1810  FieldAlign = std::max(FieldAlign, MaxAlignmentInChars);
1811  UnpackedFieldAlign = std::max(UnpackedFieldAlign, MaxAlignmentInChars);
1812 
1813  // The maximum field alignment overrides the aligned attribute.
1814  if (!MaxFieldAlignment.isZero()) {
1815  FieldAlign = std::min(FieldAlign, MaxFieldAlignment);
1816  UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignment);
1817  }
1818 
1819  // Round up the current record size to the field's alignment boundary.
1820  FieldOffset = FieldOffset.alignTo(FieldAlign);
1821  UnpackedFieldOffset = UnpackedFieldOffset.alignTo(UnpackedFieldAlign);
1822 
1823  if (UseExternalLayout) {
1824  FieldOffset = Context.toCharUnitsFromBits(
1825  updateExternalFieldOffset(D, Context.toBits(FieldOffset)));
1826 
1827  if (!IsUnion && EmptySubobjects) {
1828  // Record the fact that we're placing a field at this offset.
1829  bool Allowed = EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset);
1830  (void)Allowed;
1831  assert(Allowed && "Externally-placed field cannot be placed here");
1832  }
1833  } else {
1834  if (!IsUnion && EmptySubobjects) {
1835  // Check if we can place the field at this offset.
1836  while (!EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset)) {
1837  // We couldn't place the field at the offset. Try again at a new offset.
1838  FieldOffset += FieldAlign;
1839  }
1840  }
1841  }
1842 
1843  // Place this field at the current location.
1844  FieldOffsets.push_back(Context.toBits(FieldOffset));
1845 
1846  if (!UseExternalLayout)
1847  CheckFieldPadding(Context.toBits(FieldOffset), UnpaddedFieldOffset,
1848  Context.toBits(UnpackedFieldOffset),
1849  Context.toBits(UnpackedFieldAlign), FieldPacked, D);
1850 
1851  if (InsertExtraPadding) {
1852  CharUnits ASanAlignment = CharUnits::fromQuantity(8);
1853  CharUnits ExtraSizeForAsan = ASanAlignment;
1854  if (FieldSize % ASanAlignment)
1855  ExtraSizeForAsan +=
1856  ASanAlignment - CharUnits::fromQuantity(FieldSize % ASanAlignment);
1857  FieldSize += ExtraSizeForAsan;
1858  }
1859 
1860  // Reserve space for this field.
1861  uint64_t FieldSizeInBits = Context.toBits(FieldSize);
1862  if (IsUnion)
1863  setDataSize(std::max(getDataSizeInBits(), FieldSizeInBits));
1864  else
1865  setDataSize(FieldOffset + FieldSize);
1866 
1867  // Update the size.
1868  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1869 
1870  // Remember max struct/class alignment.
1871  UnadjustedAlignment = std::max(UnadjustedAlignment, FieldAlign);
1872  UpdateAlignment(FieldAlign, UnpackedFieldAlign);
1873 }
1874 
1875 void ItaniumRecordLayoutBuilder::FinishLayout(const NamedDecl *D) {
1876  // In C++, records cannot be of size 0.
1877  if (Context.getLangOpts().CPlusPlus && getSizeInBits() == 0) {
1878  if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) {
1879  // Compatibility with gcc requires a class (pod or non-pod)
1880  // which is not empty but of size 0; such as having fields of
1881  // array of zero-length, remains of Size 0
1882  if (RD->isEmpty())
1883  setSize(CharUnits::One());
1884  }
1885  else
1886  setSize(CharUnits::One());
1887  }
1888 
1889  // Finally, round the size of the record up to the alignment of the
1890  // record itself.
1891  uint64_t UnpaddedSize = getSizeInBits() - UnfilledBitsInLastUnit;
1892  uint64_t UnpackedSizeInBits =
1893  llvm::alignTo(getSizeInBits(), Context.toBits(UnpackedAlignment));
1894  uint64_t RoundedSize =
1895  llvm::alignTo(getSizeInBits(), Context.toBits(Alignment));
1896 
1897  if (UseExternalLayout) {
1898  // If we're inferring alignment, and the external size is smaller than
1899  // our size after we've rounded up to alignment, conservatively set the
1900  // alignment to 1.
1901  if (InferAlignment && External.Size < RoundedSize) {
1902  Alignment = CharUnits::One();
1903  InferAlignment = false;
1904  }
1905  setSize(External.Size);
1906  return;
1907  }
1908 
1909  // Set the size to the final size.
1910  setSize(RoundedSize);
1911 
1912  unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
1913  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
1914  // Warn if padding was introduced to the struct/class/union.
1915  if (getSizeInBits() > UnpaddedSize) {
1916  unsigned PadSize = getSizeInBits() - UnpaddedSize;
1917  bool InBits = true;
1918  if (PadSize % CharBitNum == 0) {
1919  PadSize = PadSize / CharBitNum;
1920  InBits = false;
1921  }
1922  Diag(RD->getLocation(), diag::warn_padded_struct_size)
1923  << Context.getTypeDeclType(RD)
1924  << PadSize
1925  << (InBits ? 1 : 0); // (byte|bit)
1926  }
1927 
1928  // Warn if we packed it unnecessarily, when the unpacked alignment is not
1929  // greater than the one after packing, the size in bits doesn't change and
1930  // the offset of each field is identical.
1931  if (Packed && UnpackedAlignment <= Alignment &&
1932  UnpackedSizeInBits == getSizeInBits() && !HasPackedField)
1933  Diag(D->getLocation(), diag::warn_unnecessary_packed)
1934  << Context.getTypeDeclType(RD);
1935  }
1936 }
1937 
1938 void ItaniumRecordLayoutBuilder::UpdateAlignment(
1939  CharUnits NewAlignment, CharUnits UnpackedNewAlignment) {
1940  // The alignment is not modified when using 'mac68k' alignment or when
1941  // we have an externally-supplied layout that also provides overall alignment.
1942  if (IsMac68kAlign || (UseExternalLayout && !InferAlignment))
1943  return;
1944 
1945  if (NewAlignment > Alignment) {
1946  assert(llvm::isPowerOf2_64(NewAlignment.getQuantity()) &&
1947  "Alignment not a power of 2");
1948  Alignment = NewAlignment;
1949  }
1950 
1951  if (UnpackedNewAlignment > UnpackedAlignment) {
1952  assert(llvm::isPowerOf2_64(UnpackedNewAlignment.getQuantity()) &&
1953  "Alignment not a power of 2");
1954  UnpackedAlignment = UnpackedNewAlignment;
1955  }
1956 }
1957 
1958 uint64_t
1959 ItaniumRecordLayoutBuilder::updateExternalFieldOffset(const FieldDecl *Field,
1960  uint64_t ComputedOffset) {
1961  uint64_t ExternalFieldOffset = External.getExternalFieldOffset(Field);
1962 
1963  if (InferAlignment && ExternalFieldOffset < ComputedOffset) {
1964  // The externally-supplied field offset is before the field offset we
1965  // computed. Assume that the structure is packed.
1966  Alignment = CharUnits::One();
1967  InferAlignment = false;
1968  }
1969 
1970  // Use the externally-supplied field offset.
1971  return ExternalFieldOffset;
1972 }
1973 
1974 /// Get diagnostic %select index for tag kind for
1975 /// field padding diagnostic message.
1976 /// WARNING: Indexes apply to particular diagnostics only!
1977 ///
1978 /// \returns diagnostic %select index.
1980  switch (Tag) {
1981  case TTK_Struct: return 0;
1982  case TTK_Interface: return 1;
1983  case TTK_Class: return 2;
1984  default: llvm_unreachable("Invalid tag kind for field padding diagnostic!");
1985  }
1986 }
1987 
1988 void ItaniumRecordLayoutBuilder::CheckFieldPadding(
1989  uint64_t Offset, uint64_t UnpaddedOffset, uint64_t UnpackedOffset,
1990  unsigned UnpackedAlign, bool isPacked, const FieldDecl *D) {
1991  // We let objc ivars without warning, objc interfaces generally are not used
1992  // for padding tricks.
1993  if (isa<ObjCIvarDecl>(D))
1994  return;
1995 
1996  // Don't warn about structs created without a SourceLocation. This can
1997  // be done by clients of the AST, such as codegen.
1998  if (D->getLocation().isInvalid())
1999  return;
2000 
2001  unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
2002 
2003  // Warn if padding was introduced to the struct/class.
2004  if (!IsUnion && Offset > UnpaddedOffset) {
2005  unsigned PadSize = Offset - UnpaddedOffset;
2006  bool InBits = true;
2007  if (PadSize % CharBitNum == 0) {
2008  PadSize = PadSize / CharBitNum;
2009  InBits = false;
2010  }
2011  if (D->getIdentifier())
2012  Diag(D->getLocation(), diag::warn_padded_struct_field)
2014  << Context.getTypeDeclType(D->getParent())
2015  << PadSize
2016  << (InBits ? 1 : 0) // (byte|bit)
2017  << D->getIdentifier();
2018  else
2019  Diag(D->getLocation(), diag::warn_padded_struct_anon_field)
2021  << Context.getTypeDeclType(D->getParent())
2022  << PadSize
2023  << (InBits ? 1 : 0); // (byte|bit)
2024  }
2025  if (isPacked && Offset != UnpackedOffset) {
2026  HasPackedField = true;
2027  }
2028 }
2029 
2031  const CXXRecordDecl *RD) {
2032  // If a class isn't polymorphic it doesn't have a key function.
2033  if (!RD->isPolymorphic())
2034  return nullptr;
2035 
2036  // A class that is not externally visible doesn't have a key function. (Or
2037  // at least, there's no point to assigning a key function to such a class;
2038  // this doesn't affect the ABI.)
2039  if (!RD->isExternallyVisible())
2040  return nullptr;
2041 
2042  // Template instantiations don't have key functions per Itanium C++ ABI 5.2.6.
2043  // Same behavior as GCC.
2045  if (TSK == TSK_ImplicitInstantiation ||
2048  return nullptr;
2049 
2050  bool allowInlineFunctions =
2052 
2053  for (const CXXMethodDecl *MD : RD->methods()) {
2054  if (!MD->isVirtual())
2055  continue;
2056 
2057  if (MD->isPure())
2058  continue;
2059 
2060  // Ignore implicit member functions, they are always marked as inline, but
2061  // they don't have a body until they're defined.
2062  if (MD->isImplicit())
2063  continue;
2064 
2065  if (MD->isInlineSpecified())
2066  continue;
2067 
2068  if (MD->hasInlineBody())
2069  continue;
2070 
2071  // Ignore inline deleted or defaulted functions.
2072  if (!MD->isUserProvided())
2073  continue;
2074 
2075  // In certain ABIs, ignore functions with out-of-line inline definitions.
2076  if (!allowInlineFunctions) {
2077  const FunctionDecl *Def;
2078  if (MD->hasBody(Def) && Def->isInlineSpecified())
2079  continue;
2080  }
2081 
2082  if (Context.getLangOpts().CUDA) {
2083  // While compiler may see key method in this TU, during CUDA
2084  // compilation we should ignore methods that are not accessible
2085  // on this side of compilation.
2086  if (Context.getLangOpts().CUDAIsDevice) {
2087  // In device mode ignore methods without __device__ attribute.
2088  if (!MD->hasAttr<CUDADeviceAttr>())
2089  continue;
2090  } else {
2091  // In host mode ignore __device__-only methods.
2092  if (!MD->hasAttr<CUDAHostAttr>() && MD->hasAttr<CUDADeviceAttr>())
2093  continue;
2094  }
2095  }
2096 
2097  // If the key function is dllimport but the class isn't, then the class has
2098  // no key function. The DLL that exports the key function won't export the
2099  // vtable in this case.
2100  if (MD->hasAttr<DLLImportAttr>() && !RD->hasAttr<DLLImportAttr>())
2101  return nullptr;
2102 
2103  // We found it.
2104  return MD;
2105  }
2106 
2107  return nullptr;
2108 }
2109 
2111  unsigned DiagID) {
2112  return Context.getDiagnostics().Report(Loc, DiagID);
2113 }
2114 
2115 /// Does the target C++ ABI require us to skip over the tail-padding
2116 /// of the given class (considering it as a base class) when allocating
2117 /// objects?
2118 static bool mustSkipTailPadding(TargetCXXABI ABI, const CXXRecordDecl *RD) {
2119  switch (ABI.getTailPaddingUseRules()) {
2121  return false;
2122 
2124  // FIXME: To the extent that this is meant to cover the Itanium ABI
2125  // rules, we should implement the restrictions about over-sized
2126  // bitfields:
2127  //
2128  // http://itanium-cxx-abi.github.io/cxx-abi/abi.html#POD :
2129  // In general, a type is considered a POD for the purposes of
2130  // layout if it is a POD type (in the sense of ISO C++
2131  // [basic.types]). However, a POD-struct or POD-union (in the
2132  // sense of ISO C++ [class]) with a bitfield member whose
2133  // declared width is wider than the declared type of the
2134  // bitfield is not a POD for the purpose of layout. Similarly,
2135  // an array type is not a POD for the purpose of layout if the
2136  // element type of the array is not a POD for the purpose of
2137  // layout.
2138  //
2139  // Where references to the ISO C++ are made in this paragraph,
2140  // the Technical Corrigendum 1 version of the standard is
2141  // intended.
2142  return RD->isPOD();
2143 
2145  // This is equivalent to RD->getTypeForDecl().isCXX11PODType(),
2146  // but with a lot of abstraction penalty stripped off. This does
2147  // assume that these properties are set correctly even in C++98
2148  // mode; fortunately, that is true because we want to assign
2149  // consistently semantics to the type-traits intrinsics (or at
2150  // least as many of them as possible).
2151  return RD->isTrivial() && RD->isCXX11StandardLayout();
2152  }
2153 
2154  llvm_unreachable("bad tail-padding use kind");
2155 }
2156 
2157 static bool isMsLayout(const ASTContext &Context) {
2158  return Context.getTargetInfo().getCXXABI().isMicrosoft();
2159 }
2160 
2161 // This section contains an implementation of struct layout that is, up to the
2162 // included tests, compatible with cl.exe (2013). The layout produced is
2163 // significantly different than those produced by the Itanium ABI. Here we note
2164 // the most important differences.
2165 //
2166 // * The alignment of bitfields in unions is ignored when computing the
2167 // alignment of the union.
2168 // * The existence of zero-width bitfield that occurs after anything other than
2169 // a non-zero length bitfield is ignored.
2170 // * There is no explicit primary base for the purposes of layout. All bases
2171 // with vfptrs are laid out first, followed by all bases without vfptrs.
2172 // * The Itanium equivalent vtable pointers are split into a vfptr (virtual
2173 // function pointer) and a vbptr (virtual base pointer). They can each be
2174 // shared with a, non-virtual bases. These bases need not be the same. vfptrs
2175 // always occur at offset 0. vbptrs can occur at an arbitrary offset and are
2176 // placed after the lexicographically last non-virtual base. This placement
2177 // is always before fields but can be in the middle of the non-virtual bases
2178 // due to the two-pass layout scheme for non-virtual-bases.
2179 // * Virtual bases sometimes require a 'vtordisp' field that is laid out before
2180 // the virtual base and is used in conjunction with virtual overrides during
2181 // construction and destruction. This is always a 4 byte value and is used as
2182 // an alternative to constructor vtables.
2183 // * vtordisps are allocated in a block of memory with size and alignment equal
2184 // to the alignment of the completed structure (before applying __declspec(
2185 // align())). The vtordisp always occur at the end of the allocation block,
2186 // immediately prior to the virtual base.
2187 // * vfptrs are injected after all bases and fields have been laid out. In
2188 // order to guarantee proper alignment of all fields, the vfptr injection
2189 // pushes all bases and fields back by the alignment imposed by those bases
2190 // and fields. This can potentially add a significant amount of padding.
2191 // vfptrs are always injected at offset 0.
2192 // * vbptrs are injected after all bases and fields have been laid out. In
2193 // order to guarantee proper alignment of all fields, the vfptr injection
2194 // pushes all bases and fields back by the alignment imposed by those bases
2195 // and fields. This can potentially add a significant amount of padding.
2196 // vbptrs are injected immediately after the last non-virtual base as
2197 // lexicographically ordered in the code. If this site isn't pointer aligned
2198 // the vbptr is placed at the next properly aligned location. Enough padding
2199 // is added to guarantee a fit.
2200 // * The last zero sized non-virtual base can be placed at the end of the
2201 // struct (potentially aliasing another object), or may alias with the first
2202 // field, even if they are of the same type.
2203 // * The last zero size virtual base may be placed at the end of the struct
2204 // potentially aliasing another object.
2205 // * The ABI attempts to avoid aliasing of zero sized bases by adding padding
2206 // between bases or vbases with specific properties. The criteria for
2207 // additional padding between two bases is that the first base is zero sized
2208 // or ends with a zero sized subobject and the second base is zero sized or
2209 // trails with a zero sized base or field (sharing of vfptrs can reorder the
2210 // layout of the so the leading base is not always the first one declared).
2211 // This rule does take into account fields that are not records, so padding
2212 // will occur even if the last field is, e.g. an int. The padding added for
2213 // bases is 1 byte. The padding added between vbases depends on the alignment
2214 // of the object but is at least 4 bytes (in both 32 and 64 bit modes).
2215 // * There is no concept of non-virtual alignment, non-virtual alignment and
2216 // alignment are always identical.
2217 // * There is a distinction between alignment and required alignment.
2218 // __declspec(align) changes the required alignment of a struct. This
2219 // alignment is _always_ obeyed, even in the presence of #pragma pack. A
2220 // record inherits required alignment from all of its fields and bases.
2221 // * __declspec(align) on bitfields has the effect of changing the bitfield's
2222 // alignment instead of its required alignment. This is the only known way
2223 // to make the alignment of a struct bigger than 8. Interestingly enough
2224 // this alignment is also immune to the effects of #pragma pack and can be
2225 // used to create structures with large alignment under #pragma pack.
2226 // However, because it does not impact required alignment, such a structure,
2227 // when used as a field or base, will not be aligned if #pragma pack is
2228 // still active at the time of use.
2229 //
2230 // Known incompatibilities:
2231 // * all: #pragma pack between fields in a record
2232 // * 2010 and back: If the last field in a record is a bitfield, every object
2233 // laid out after the record will have extra padding inserted before it. The
2234 // extra padding will have size equal to the size of the storage class of the
2235 // bitfield. 0 sized bitfields don't exhibit this behavior and the extra
2236 // padding can be avoided by adding a 0 sized bitfield after the non-zero-
2237 // sized bitfield.
2238 // * 2012 and back: In 64-bit mode, if the alignment of a record is 16 or
2239 // greater due to __declspec(align()) then a second layout phase occurs after
2240 // The locations of the vf and vb pointers are known. This layout phase
2241 // suffers from the "last field is a bitfield" bug in 2010 and results in
2242 // _every_ field getting padding put in front of it, potentially including the
2243 // vfptr, leaving the vfprt at a non-zero location which results in a fault if
2244 // anything tries to read the vftbl. The second layout phase also treats
2245 // bitfields as separate entities and gives them each storage rather than
2246 // packing them. Additionally, because this phase appears to perform a
2247 // (an unstable) sort on the members before laying them out and because merged
2248 // bitfields have the same address, the bitfields end up in whatever order
2249 // the sort left them in, a behavior we could never hope to replicate.
2250 
2251 namespace {
2252 struct MicrosoftRecordLayoutBuilder {
2253  struct ElementInfo {
2254  CharUnits Size;
2255  CharUnits Alignment;
2256  };
2257  typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
2258  MicrosoftRecordLayoutBuilder(const ASTContext &Context) : Context(Context) {}
2259 private:
2260  MicrosoftRecordLayoutBuilder(const MicrosoftRecordLayoutBuilder &) = delete;
2261  void operator=(const MicrosoftRecordLayoutBuilder &) = delete;
2262 public:
2263  void layout(const RecordDecl *RD);
2264  void cxxLayout(const CXXRecordDecl *RD);
2265  /// Initializes size and alignment and honors some flags.
2266  void initializeLayout(const RecordDecl *RD);
2267  /// Initialized C++ layout, compute alignment and virtual alignment and
2268  /// existence of vfptrs and vbptrs. Alignment is needed before the vfptr is
2269  /// laid out.
2270  void initializeCXXLayout(const CXXRecordDecl *RD);
2271  void layoutNonVirtualBases(const CXXRecordDecl *RD);
2272  void layoutNonVirtualBase(const CXXRecordDecl *RD,
2273  const CXXRecordDecl *BaseDecl,
2274  const ASTRecordLayout &BaseLayout,
2275  const ASTRecordLayout *&PreviousBaseLayout);
2276  void injectVFPtr(const CXXRecordDecl *RD);
2277  void injectVBPtr(const CXXRecordDecl *RD);
2278  /// Lays out the fields of the record. Also rounds size up to
2279  /// alignment.
2280  void layoutFields(const RecordDecl *RD);
2281  void layoutField(const FieldDecl *FD);
2282  void layoutBitField(const FieldDecl *FD);
2283  /// Lays out a single zero-width bit-field in the record and handles
2284  /// special cases associated with zero-width bit-fields.
2285  void layoutZeroWidthBitField(const FieldDecl *FD);
2286  void layoutVirtualBases(const CXXRecordDecl *RD);
2287  void finalizeLayout(const RecordDecl *RD);
2288  /// Gets the size and alignment of a base taking pragma pack and
2289  /// __declspec(align) into account.
2290  ElementInfo getAdjustedElementInfo(const ASTRecordLayout &Layout);
2291  /// Gets the size and alignment of a field taking pragma pack and
2292  /// __declspec(align) into account. It also updates RequiredAlignment as a
2293  /// side effect because it is most convenient to do so here.
2294  ElementInfo getAdjustedElementInfo(const FieldDecl *FD);
2295  /// Places a field at an offset in CharUnits.
2296  void placeFieldAtOffset(CharUnits FieldOffset) {
2297  FieldOffsets.push_back(Context.toBits(FieldOffset));
2298  }
2299  /// Places a bitfield at a bit offset.
2300  void placeFieldAtBitOffset(uint64_t FieldOffset) {
2301  FieldOffsets.push_back(FieldOffset);
2302  }
2303  /// Compute the set of virtual bases for which vtordisps are required.
2304  void computeVtorDispSet(
2305  llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtorDispSet,
2306  const CXXRecordDecl *RD) const;
2307  const ASTContext &Context;
2308  /// The size of the record being laid out.
2309  CharUnits Size;
2310  /// The non-virtual size of the record layout.
2311  CharUnits NonVirtualSize;
2312  /// The data size of the record layout.
2313  CharUnits DataSize;
2314  /// The current alignment of the record layout.
2315  CharUnits Alignment;
2316  /// The maximum allowed field alignment. This is set by #pragma pack.
2317  CharUnits MaxFieldAlignment;
2318  /// The alignment that this record must obey. This is imposed by
2319  /// __declspec(align()) on the record itself or one of its fields or bases.
2320  CharUnits RequiredAlignment;
2321  /// The size of the allocation of the currently active bitfield.
2322  /// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield
2323  /// is true.
2324  CharUnits CurrentBitfieldSize;
2325  /// Offset to the virtual base table pointer (if one exists).
2326  CharUnits VBPtrOffset;
2327  /// Minimum record size possible.
2328  CharUnits MinEmptyStructSize;
2329  /// The size and alignment info of a pointer.
2330  ElementInfo PointerInfo;
2331  /// The primary base class (if one exists).
2332  const CXXRecordDecl *PrimaryBase;
2333  /// The class we share our vb-pointer with.
2334  const CXXRecordDecl *SharedVBPtrBase;
2335  /// The collection of field offsets.
2336  SmallVector<uint64_t, 16> FieldOffsets;
2337  /// Base classes and their offsets in the record.
2338  BaseOffsetsMapTy Bases;
2339  /// virtual base classes and their offsets in the record.
2341  /// The number of remaining bits in our last bitfield allocation.
2342  /// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield is
2343  /// true.
2344  unsigned RemainingBitsInField;
2345  bool IsUnion : 1;
2346  /// True if the last field laid out was a bitfield and was not 0
2347  /// width.
2348  bool LastFieldIsNonZeroWidthBitfield : 1;
2349  /// True if the class has its own vftable pointer.
2350  bool HasOwnVFPtr : 1;
2351  /// True if the class has a vbtable pointer.
2352  bool HasVBPtr : 1;
2353  /// True if the last sub-object within the type is zero sized or the
2354  /// object itself is zero sized. This *does not* count members that are not
2355  /// records. Only used for MS-ABI.
2356  bool EndsWithZeroSizedObject : 1;
2357  /// True if this class is zero sized or first base is zero sized or
2358  /// has this property. Only used for MS-ABI.
2359  bool LeadsWithZeroSizedBase : 1;
2360 
2361  /// True if the external AST source provided a layout for this record.
2362  bool UseExternalLayout : 1;
2363 
2364  /// The layout provided by the external AST source. Only active if
2365  /// UseExternalLayout is true.
2366  ExternalLayout External;
2367 };
2368 } // namespace
2369 
2370 MicrosoftRecordLayoutBuilder::ElementInfo
2371 MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
2372  const ASTRecordLayout &Layout) {
2373  ElementInfo Info;
2374  Info.Alignment = Layout.getAlignment();
2375  // Respect pragma pack.
2376  if (!MaxFieldAlignment.isZero())
2377  Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
2378  // Track zero-sized subobjects here where it's already available.
2379  EndsWithZeroSizedObject = Layout.endsWithZeroSizedObject();
2380  // Respect required alignment, this is necessary because we may have adjusted
2381  // the alignment in the case of pragam pack. Note that the required alignment
2382  // doesn't actually apply to the struct alignment at this point.
2383  Alignment = std::max(Alignment, Info.Alignment);
2384  RequiredAlignment = std::max(RequiredAlignment, Layout.getRequiredAlignment());
2385  Info.Alignment = std::max(Info.Alignment, Layout.getRequiredAlignment());
2386  Info.Size = Layout.getNonVirtualSize();
2387  return Info;
2388 }
2389 
2390 MicrosoftRecordLayoutBuilder::ElementInfo
2391 MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
2392  const FieldDecl *FD) {
2393  // Get the alignment of the field type's natural alignment, ignore any
2394  // alignment attributes.
2395  ElementInfo Info;
2396  std::tie(Info.Size, Info.Alignment) =
2398  // Respect align attributes on the field.
2399  CharUnits FieldRequiredAlignment =
2400  Context.toCharUnitsFromBits(FD->getMaxAlignment());
2401  // Respect align attributes on the type.
2402  if (Context.isAlignmentRequired(FD->getType()))
2403  FieldRequiredAlignment = std::max(
2404  Context.getTypeAlignInChars(FD->getType()), FieldRequiredAlignment);
2405  // Respect attributes applied to subobjects of the field.
2406  if (FD->isBitField())
2407  // For some reason __declspec align impacts alignment rather than required
2408  // alignment when it is applied to bitfields.
2409  Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
2410  else {
2411  if (auto RT =
2413  auto const &Layout = Context.getASTRecordLayout(RT->getDecl());
2414  EndsWithZeroSizedObject = Layout.endsWithZeroSizedObject();
2415  FieldRequiredAlignment = std::max(FieldRequiredAlignment,
2416  Layout.getRequiredAlignment());
2417  }
2418  // Capture required alignment as a side-effect.
2419  RequiredAlignment = std::max(RequiredAlignment, FieldRequiredAlignment);
2420  }
2421  // Respect pragma pack, attribute pack and declspec align
2422  if (!MaxFieldAlignment.isZero())
2423  Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
2424  if (FD->hasAttr<PackedAttr>())
2425  Info.Alignment = CharUnits::One();
2426  Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
2427  return Info;
2428 }
2429 
2430 void MicrosoftRecordLayoutBuilder::layout(const RecordDecl *RD) {
2431  // For C record layout, zero-sized records always have size 4.
2432  MinEmptyStructSize = CharUnits::fromQuantity(4);
2433  initializeLayout(RD);
2434  layoutFields(RD);
2435  DataSize = Size = Size.alignTo(Alignment);
2436  RequiredAlignment = std::max(
2437  RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
2438  finalizeLayout(RD);
2439 }
2440 
2441 void MicrosoftRecordLayoutBuilder::cxxLayout(const CXXRecordDecl *RD) {
2442  // The C++ standard says that empty structs have size 1.
2443  MinEmptyStructSize = CharUnits::One();
2444  initializeLayout(RD);
2445  initializeCXXLayout(RD);
2446  layoutNonVirtualBases(RD);
2447  layoutFields(RD);
2448  injectVBPtr(RD);
2449  injectVFPtr(RD);
2450  if (HasOwnVFPtr || (HasVBPtr && !SharedVBPtrBase))
2451  Alignment = std::max(Alignment, PointerInfo.Alignment);
2452  auto RoundingAlignment = Alignment;
2453  if (!MaxFieldAlignment.isZero())
2454  RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
2455  if (!UseExternalLayout)
2456  Size = Size.alignTo(RoundingAlignment);
2457  NonVirtualSize = Size;
2458  RequiredAlignment = std::max(
2459  RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
2460  layoutVirtualBases(RD);
2461  finalizeLayout(RD);
2462 }
2463 
2464 void MicrosoftRecordLayoutBuilder::initializeLayout(const RecordDecl *RD) {
2465  IsUnion = RD->isUnion();
2466  Size = CharUnits::Zero();
2467  Alignment = CharUnits::One();
2468  // In 64-bit mode we always perform an alignment step after laying out vbases.
2469  // In 32-bit mode we do not. The check to see if we need to perform alignment
2470  // checks the RequiredAlignment field and performs alignment if it isn't 0.
2471  RequiredAlignment = Context.getTargetInfo().getTriple().isArch64Bit()
2472  ? CharUnits::One()
2473  : CharUnits::Zero();
2474  // Compute the maximum field alignment.
2475  MaxFieldAlignment = CharUnits::Zero();
2476  // Honor the default struct packing maximum alignment flag.
2477  if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct)
2478  MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
2479  // Honor the packing attribute. The MS-ABI ignores pragma pack if its larger
2480  // than the pointer size.
2481  if (const MaxFieldAlignmentAttr *MFAA = RD->getAttr<MaxFieldAlignmentAttr>()){
2482  unsigned PackedAlignment = MFAA->getAlignment();
2483  if (PackedAlignment <= Context.getTargetInfo().getPointerWidth(0))
2484  MaxFieldAlignment = Context.toCharUnitsFromBits(PackedAlignment);
2485  }
2486  // Packed attribute forces max field alignment to be 1.
2487  if (RD->hasAttr<PackedAttr>())
2488  MaxFieldAlignment = CharUnits::One();
2489 
2490  // Try to respect the external layout if present.
2491  UseExternalLayout = false;
2492  if (ExternalASTSource *Source = Context.getExternalSource())
2493  UseExternalLayout = Source->layoutRecordType(
2494  RD, External.Size, External.Align, External.FieldOffsets,
2495  External.BaseOffsets, External.VirtualBaseOffsets);
2496 }
2497 
2498 void
2499 MicrosoftRecordLayoutBuilder::initializeCXXLayout(const CXXRecordDecl *RD) {
2500  EndsWithZeroSizedObject = false;
2501  LeadsWithZeroSizedBase = false;
2502  HasOwnVFPtr = false;
2503  HasVBPtr = false;
2504  PrimaryBase = nullptr;
2505  SharedVBPtrBase = nullptr;
2506  // Calculate pointer size and alignment. These are used for vfptr and vbprt
2507  // injection.
2508  PointerInfo.Size =
2509  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
2510  PointerInfo.Alignment =
2511  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
2512  // Respect pragma pack.
2513  if (!MaxFieldAlignment.isZero())
2514  PointerInfo.Alignment = std::min(PointerInfo.Alignment, MaxFieldAlignment);
2515 }
2516 
2517 void
2518 MicrosoftRecordLayoutBuilder::layoutNonVirtualBases(const CXXRecordDecl *RD) {
2519  // The MS-ABI lays out all bases that contain leading vfptrs before it lays
2520  // out any bases that do not contain vfptrs. We implement this as two passes
2521  // over the bases. This approach guarantees that the primary base is laid out
2522  // first. We use these passes to calculate some additional aggregated
2523  // information about the bases, such as required alignment and the presence of
2524  // zero sized members.
2525  const ASTRecordLayout *PreviousBaseLayout = nullptr;
2526  // Iterate through the bases and lay out the non-virtual ones.
2527  for (const CXXBaseSpecifier &Base : RD->bases()) {
2528  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2529  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2530  // Mark and skip virtual bases.
2531  if (Base.isVirtual()) {
2532  HasVBPtr = true;
2533  continue;
2534  }
2535  // Check for a base to share a VBPtr with.
2536  if (!SharedVBPtrBase && BaseLayout.hasVBPtr()) {
2537  SharedVBPtrBase = BaseDecl;
2538  HasVBPtr = true;
2539  }
2540  // Only lay out bases with extendable VFPtrs on the first pass.
2541  if (!BaseLayout.hasExtendableVFPtr())
2542  continue;
2543  // If we don't have a primary base, this one qualifies.
2544  if (!PrimaryBase) {
2545  PrimaryBase = BaseDecl;
2546  LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
2547  }
2548  // Lay out the base.
2549  layoutNonVirtualBase(RD, BaseDecl, BaseLayout, PreviousBaseLayout);
2550  }
2551  // Figure out if we need a fresh VFPtr for this class.
2552  if (!PrimaryBase && RD->isDynamicClass())
2554  e = RD->method_end();
2555  !HasOwnVFPtr && i != e; ++i)
2556  HasOwnVFPtr = i->isVirtual() && i->size_overridden_methods() == 0;
2557  // If we don't have a primary base then we have a leading object that could
2558  // itself lead with a zero-sized object, something we track.
2559  bool CheckLeadingLayout = !PrimaryBase;
2560  // Iterate through the bases and lay out the non-virtual ones.
2561  for (const CXXBaseSpecifier &Base : RD->bases()) {
2562  if (Base.isVirtual())
2563  continue;
2564  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2565  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2566  // Only lay out bases without extendable VFPtrs on the second pass.
2567  if (BaseLayout.hasExtendableVFPtr()) {
2568  VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
2569  continue;
2570  }
2571  // If this is the first layout, check to see if it leads with a zero sized
2572  // object. If it does, so do we.
2573  if (CheckLeadingLayout) {
2574  CheckLeadingLayout = false;
2575  LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
2576  }
2577  // Lay out the base.
2578  layoutNonVirtualBase(RD, BaseDecl, BaseLayout, PreviousBaseLayout);
2579  VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
2580  }
2581  // Set our VBPtroffset if we know it at this point.
2582  if (!HasVBPtr)
2583  VBPtrOffset = CharUnits::fromQuantity(-1);
2584  else if (SharedVBPtrBase) {
2585  const ASTRecordLayout &Layout = Context.getASTRecordLayout(SharedVBPtrBase);
2586  VBPtrOffset = Bases[SharedVBPtrBase] + Layout.getVBPtrOffset();
2587  }
2588 }
2589 
2590 static bool recordUsesEBO(const RecordDecl *RD) {
2591  if (!isa<CXXRecordDecl>(RD))
2592  return false;
2593  if (RD->hasAttr<EmptyBasesAttr>())
2594  return true;
2595  if (auto *LVA = RD->getAttr<LayoutVersionAttr>())
2596  // TODO: Double check with the next version of MSVC.
2597  if (LVA->getVersion() <= LangOptions::MSVC2015)
2598  return false;
2599  // TODO: Some later version of MSVC will change the default behavior of the
2600  // compiler to enable EBO by default. When this happens, we will need an
2601  // additional isCompatibleWithMSVC check.
2602  return false;
2603 }
2604 
2605 void MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(
2606  const CXXRecordDecl *RD,
2607  const CXXRecordDecl *BaseDecl,
2608  const ASTRecordLayout &BaseLayout,
2609  const ASTRecordLayout *&PreviousBaseLayout) {
2610  // Insert padding between two bases if the left first one is zero sized or
2611  // contains a zero sized subobject and the right is zero sized or one leads
2612  // with a zero sized base.
2613  bool MDCUsesEBO = recordUsesEBO(RD);
2614  if (PreviousBaseLayout && PreviousBaseLayout->endsWithZeroSizedObject() &&
2615  BaseLayout.leadsWithZeroSizedBase() && !MDCUsesEBO)
2616  Size++;
2617  ElementInfo Info = getAdjustedElementInfo(BaseLayout);
2618  CharUnits BaseOffset;
2619 
2620  // Respect the external AST source base offset, if present.
2621  bool FoundBase = false;
2622  if (UseExternalLayout) {
2623  FoundBase = External.getExternalNVBaseOffset(BaseDecl, BaseOffset);
2624  if (FoundBase) {
2625  assert(BaseOffset >= Size && "base offset already allocated");
2626  Size = BaseOffset;
2627  }
2628  }
2629 
2630  if (!FoundBase) {
2631  if (MDCUsesEBO && BaseDecl->isEmpty()) {
2632  assert(BaseLayout.getNonVirtualSize() == CharUnits::Zero());
2633  BaseOffset = CharUnits::Zero();
2634  } else {
2635  // Otherwise, lay the base out at the end of the MDC.
2636  BaseOffset = Size = Size.alignTo(Info.Alignment);
2637  }
2638  }
2639  Bases.insert(std::make_pair(BaseDecl, BaseOffset));
2640  Size += BaseLayout.getNonVirtualSize();
2641  PreviousBaseLayout = &BaseLayout;
2642 }
2643 
2644 void MicrosoftRecordLayoutBuilder::layoutFields(const RecordDecl *RD) {
2645  LastFieldIsNonZeroWidthBitfield = false;
2646  for (const FieldDecl *Field : RD->fields())
2647  layoutField(Field);
2648 }
2649 
2650 void MicrosoftRecordLayoutBuilder::layoutField(const FieldDecl *FD) {
2651  if (FD->isBitField()) {
2652  layoutBitField(FD);
2653  return;
2654  }
2655  LastFieldIsNonZeroWidthBitfield = false;
2656  ElementInfo Info = getAdjustedElementInfo(FD);
2657  Alignment = std::max(Alignment, Info.Alignment);
2658  CharUnits FieldOffset;
2659  if (UseExternalLayout)
2660  FieldOffset =
2661  Context.toCharUnitsFromBits(External.getExternalFieldOffset(FD));
2662  else if (IsUnion)
2663  FieldOffset = CharUnits::Zero();
2664  else
2665  FieldOffset = Size.alignTo(Info.Alignment);
2666  placeFieldAtOffset(FieldOffset);
2667  Size = std::max(Size, FieldOffset + Info.Size);
2668 }
2669 
2670 void MicrosoftRecordLayoutBuilder::layoutBitField(const FieldDecl *FD) {
2671  unsigned Width = FD->getBitWidthValue(Context);
2672  if (Width == 0) {
2673  layoutZeroWidthBitField(FD);
2674  return;
2675  }
2676  ElementInfo Info = getAdjustedElementInfo(FD);
2677  // Clamp the bitfield to a containable size for the sake of being able
2678  // to lay them out. Sema will throw an error.
2679  if (Width > Context.toBits(Info.Size))
2680  Width = Context.toBits(Info.Size);
2681  // Check to see if this bitfield fits into an existing allocation. Note:
2682  // MSVC refuses to pack bitfields of formal types with different sizes
2683  // into the same allocation.
2684  if (!UseExternalLayout && !IsUnion && LastFieldIsNonZeroWidthBitfield &&
2685  CurrentBitfieldSize == Info.Size && Width <= RemainingBitsInField) {
2686  placeFieldAtBitOffset(Context.toBits(Size) - RemainingBitsInField);
2687  RemainingBitsInField -= Width;
2688  return;
2689  }
2690  LastFieldIsNonZeroWidthBitfield = true;
2691  CurrentBitfieldSize = Info.Size;
2692  if (UseExternalLayout) {
2693  auto FieldBitOffset = External.getExternalFieldOffset(FD);
2694  placeFieldAtBitOffset(FieldBitOffset);
2695  auto NewSize = Context.toCharUnitsFromBits(
2696  llvm::alignTo(FieldBitOffset + Width, Context.getCharWidth()));
2697  Size = std::max(Size, NewSize);
2698  Alignment = std::max(Alignment, Info.Alignment);
2699  } else if (IsUnion) {
2700  placeFieldAtOffset(CharUnits::Zero());
2701  Size = std::max(Size, Info.Size);
2702  // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
2703  } else {
2704  // Allocate a new block of memory and place the bitfield in it.
2705  CharUnits FieldOffset = Size.alignTo(Info.Alignment);
2706  placeFieldAtOffset(FieldOffset);
2707  Size = FieldOffset + Info.Size;
2708  Alignment = std::max(Alignment, Info.Alignment);
2709  RemainingBitsInField = Context.toBits(Info.Size) - Width;
2710  }
2711 }
2712 
2713 void
2714 MicrosoftRecordLayoutBuilder::layoutZeroWidthBitField(const FieldDecl *FD) {
2715  // Zero-width bitfields are ignored unless they follow a non-zero-width
2716  // bitfield.
2717  if (!LastFieldIsNonZeroWidthBitfield) {
2718  placeFieldAtOffset(IsUnion ? CharUnits::Zero() : Size);
2719  // TODO: Add a Sema warning that MS ignores alignment for zero
2720  // sized bitfields that occur after zero-size bitfields or non-bitfields.
2721  return;
2722  }
2723  LastFieldIsNonZeroWidthBitfield = false;
2724  ElementInfo Info = getAdjustedElementInfo(FD);
2725  if (IsUnion) {
2726  placeFieldAtOffset(CharUnits::Zero());
2727  Size = std::max(Size, Info.Size);
2728  // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
2729  } else {
2730  // Round up the current record size to the field's alignment boundary.
2731  CharUnits FieldOffset = Size.alignTo(Info.Alignment);
2732  placeFieldAtOffset(FieldOffset);
2733  Size = FieldOffset;
2734  Alignment = std::max(Alignment, Info.Alignment);
2735  }
2736 }
2737 
2738 void MicrosoftRecordLayoutBuilder::injectVBPtr(const CXXRecordDecl *RD) {
2739  if (!HasVBPtr || SharedVBPtrBase)
2740  return;
2741  // Inject the VBPointer at the injection site.
2742  CharUnits InjectionSite = VBPtrOffset;
2743  // But before we do, make sure it's properly aligned.
2744  VBPtrOffset = VBPtrOffset.alignTo(PointerInfo.Alignment);
2745  // Shift everything after the vbptr down, unless we're using an external
2746  // layout.
2747  if (UseExternalLayout)
2748  return;
2749  // Determine where the first field should be laid out after the vbptr.
2750  CharUnits FieldStart = VBPtrOffset + PointerInfo.Size;
2751  // Make sure that the amount we push the fields back by is a multiple of the
2752  // alignment.
2753  CharUnits Offset = (FieldStart - InjectionSite)
2754  .alignTo(std::max(RequiredAlignment, Alignment));
2755  Size += Offset;
2756  for (uint64_t &FieldOffset : FieldOffsets)
2757  FieldOffset += Context.toBits(Offset);
2758  for (BaseOffsetsMapTy::value_type &Base : Bases)
2759  if (Base.second >= InjectionSite)
2760  Base.second += Offset;
2761 }
2762 
2763 void MicrosoftRecordLayoutBuilder::injectVFPtr(const CXXRecordDecl *RD) {
2764  if (!HasOwnVFPtr)
2765  return;
2766  // Make sure that the amount we push the struct back by is a multiple of the
2767  // alignment.
2768  CharUnits Offset =
2769  PointerInfo.Size.alignTo(std::max(RequiredAlignment, Alignment));
2770  // Push back the vbptr, but increase the size of the object and push back
2771  // regular fields by the offset only if not using external record layout.
2772  if (HasVBPtr)
2773  VBPtrOffset += Offset;
2774 
2775  if (UseExternalLayout)
2776  return;
2777 
2778  Size += Offset;
2779 
2780  // If we're using an external layout, the fields offsets have already
2781  // accounted for this adjustment.
2782  for (uint64_t &FieldOffset : FieldOffsets)
2783  FieldOffset += Context.toBits(Offset);
2784  for (BaseOffsetsMapTy::value_type &Base : Bases)
2785  Base.second += Offset;
2786 }
2787 
2788 void MicrosoftRecordLayoutBuilder::layoutVirtualBases(const CXXRecordDecl *RD) {
2789  if (!HasVBPtr)
2790  return;
2791  // Vtordisps are always 4 bytes (even in 64-bit mode)
2792  CharUnits VtorDispSize = CharUnits::fromQuantity(4);
2793  CharUnits VtorDispAlignment = VtorDispSize;
2794  // vtordisps respect pragma pack.
2795  if (!MaxFieldAlignment.isZero())
2796  VtorDispAlignment = std::min(VtorDispAlignment, MaxFieldAlignment);
2797  // The alignment of the vtordisp is at least the required alignment of the
2798  // entire record. This requirement may be present to support vtordisp
2799  // injection.
2800  for (const CXXBaseSpecifier &VBase : RD->vbases()) {
2801  const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
2802  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2803  RequiredAlignment =
2804  std::max(RequiredAlignment, BaseLayout.getRequiredAlignment());
2805  }
2806  VtorDispAlignment = std::max(VtorDispAlignment, RequiredAlignment);
2807  // Compute the vtordisp set.
2808  llvm::SmallPtrSet<const CXXRecordDecl *, 2> HasVtorDispSet;
2809  computeVtorDispSet(HasVtorDispSet, RD);
2810  // Iterate through the virtual bases and lay them out.
2811  const ASTRecordLayout *PreviousBaseLayout = nullptr;
2812  for (const CXXBaseSpecifier &VBase : RD->vbases()) {
2813  const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
2814  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2815  bool HasVtordisp = HasVtorDispSet.count(BaseDecl) > 0;
2816  // Insert padding between two bases if the left first one is zero sized or
2817  // contains a zero sized subobject and the right is zero sized or one leads
2818  // with a zero sized base. The padding between virtual bases is 4
2819  // bytes (in both 32 and 64 bits modes) and always involves rounding up to
2820  // the required alignment, we don't know why.
2821  if ((PreviousBaseLayout && PreviousBaseLayout->endsWithZeroSizedObject() &&
2822  BaseLayout.leadsWithZeroSizedBase() && !recordUsesEBO(RD)) ||
2823  HasVtordisp) {
2824  Size = Size.alignTo(VtorDispAlignment) + VtorDispSize;
2825  Alignment = std::max(VtorDispAlignment, Alignment);
2826  }
2827  // Insert the virtual base.
2828  ElementInfo Info = getAdjustedElementInfo(BaseLayout);
2829  CharUnits BaseOffset;
2830 
2831  // Respect the external AST source base offset, if present.
2832  bool FoundBase = false;
2833  if (UseExternalLayout) {
2834  FoundBase = External.getExternalVBaseOffset(BaseDecl, BaseOffset);
2835  if (FoundBase)
2836  assert(BaseOffset >= Size && "base offset already allocated");
2837  }
2838  if (!FoundBase)
2839  BaseOffset = Size.alignTo(Info.Alignment);
2840 
2841  VBases.insert(std::make_pair(BaseDecl,
2842  ASTRecordLayout::VBaseInfo(BaseOffset, HasVtordisp)));
2843  Size = BaseOffset + BaseLayout.getNonVirtualSize();
2844  PreviousBaseLayout = &BaseLayout;
2845  }
2846 }
2847 
2848 void MicrosoftRecordLayoutBuilder::finalizeLayout(const RecordDecl *RD) {
2849  // Respect required alignment. Note that in 32-bit mode Required alignment
2850  // may be 0 and cause size not to be updated.
2851  DataSize = Size;
2852  if (!RequiredAlignment.isZero()) {
2853  Alignment = std::max(Alignment, RequiredAlignment);
2854  auto RoundingAlignment = Alignment;
2855  if (!MaxFieldAlignment.isZero())
2856  RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
2857  RoundingAlignment = std::max(RoundingAlignment, RequiredAlignment);
2858  Size = Size.alignTo(RoundingAlignment);
2859  }
2860  if (Size.isZero()) {
2861  if (!recordUsesEBO(RD) || !cast<CXXRecordDecl>(RD)->isEmpty()) {
2862  EndsWithZeroSizedObject = true;
2863  LeadsWithZeroSizedBase = true;
2864  }
2865  // Zero-sized structures have size equal to their alignment if a
2866  // __declspec(align) came into play.
2867  if (RequiredAlignment >= MinEmptyStructSize)
2868  Size = Alignment;
2869  else
2870  Size = MinEmptyStructSize;
2871  }
2872 
2873  if (UseExternalLayout) {
2874  Size = Context.toCharUnitsFromBits(External.Size);
2875  if (External.Align)
2876  Alignment = Context.toCharUnitsFromBits(External.Align);
2877  }
2878 }
2879 
2880 // Recursively walks the non-virtual bases of a class and determines if any of
2881 // them are in the bases with overridden methods set.
2882 static bool
2883 RequiresVtordisp(const llvm::SmallPtrSetImpl<const CXXRecordDecl *> &
2884  BasesWithOverriddenMethods,
2885  const CXXRecordDecl *RD) {
2886  if (BasesWithOverriddenMethods.count(RD))
2887  return true;
2888  // If any of a virtual bases non-virtual bases (recursively) requires a
2889  // vtordisp than so does this virtual base.
2890  for (const CXXBaseSpecifier &Base : RD->bases())
2891  if (!Base.isVirtual() &&
2892  RequiresVtordisp(BasesWithOverriddenMethods,
2893  Base.getType()->getAsCXXRecordDecl()))
2894  return true;
2895  return false;
2896 }
2897 
2898 void MicrosoftRecordLayoutBuilder::computeVtorDispSet(
2899  llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtordispSet,
2900  const CXXRecordDecl *RD) const {
2901  // /vd2 or #pragma vtordisp(2): Always use vtordisps for virtual bases with
2902  // vftables.
2903  if (RD->getMSVtorDispMode() == MSVtorDispAttr::ForVFTable) {
2904  for (const CXXBaseSpecifier &Base : RD->vbases()) {
2905  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2906  const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
2907  if (Layout.hasExtendableVFPtr())
2908  HasVtordispSet.insert(BaseDecl);
2909  }
2910  return;
2911  }
2912 
2913  // If any of our bases need a vtordisp for this type, so do we. Check our
2914  // direct bases for vtordisp requirements.
2915  for (const CXXBaseSpecifier &Base : RD->bases()) {
2916  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2917  const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
2918  for (const auto &bi : Layout.getVBaseOffsetsMap())
2919  if (bi.second.hasVtorDisp())
2920  HasVtordispSet.insert(bi.first);
2921  }
2922  // We don't introduce any additional vtordisps if either:
2923  // * A user declared constructor or destructor aren't declared.
2924  // * #pragma vtordisp(0) or the /vd0 flag are in use.
2925  if ((!RD->hasUserDeclaredConstructor() && !RD->hasUserDeclaredDestructor()) ||
2926  RD->getMSVtorDispMode() == MSVtorDispAttr::Never)
2927  return;
2928  // /vd1 or #pragma vtordisp(1): Try to guess based on whether we think it's
2929  // possible for a partially constructed object with virtual base overrides to
2930  // escape a non-trivial constructor.
2931  assert(RD->getMSVtorDispMode() == MSVtorDispAttr::ForVBaseOverride);
2932  // Compute a set of base classes which define methods we override. A virtual
2933  // base in this set will require a vtordisp. A virtual base that transitively
2934  // contains one of these bases as a non-virtual base will also require a
2935  // vtordisp.
2936  llvm::SmallPtrSet<const CXXMethodDecl *, 8> Work;
2937  llvm::SmallPtrSet<const CXXRecordDecl *, 2> BasesWithOverriddenMethods;
2938  // Seed the working set with our non-destructor, non-pure virtual methods.
2939  for (const CXXMethodDecl *MD : RD->methods())
2940  if (MD->isVirtual() && !isa<CXXDestructorDecl>(MD) && !MD->isPure())
2941  Work.insert(MD);
2942  while (!Work.empty()) {
2943  const CXXMethodDecl *MD = *Work.begin();
2944  auto MethodRange = MD->overridden_methods();
2945  // If a virtual method has no-overrides it lives in its parent's vtable.
2946  if (MethodRange.begin() == MethodRange.end())
2947  BasesWithOverriddenMethods.insert(MD->getParent());
2948  else
2949  Work.insert(MethodRange.begin(), MethodRange.end());
2950  // We've finished processing this element, remove it from the working set.
2951  Work.erase(MD);
2952  }
2953  // For each of our virtual bases, check if it is in the set of overridden
2954  // bases or if it transitively contains a non-virtual base that is.
2955  for (const CXXBaseSpecifier &Base : RD->vbases()) {
2956  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2957  if (!HasVtordispSet.count(BaseDecl) &&
2958  RequiresVtordisp(BasesWithOverriddenMethods, BaseDecl))
2959  HasVtordispSet.insert(BaseDecl);
2960  }
2961 }
2962 
2963 /// getASTRecordLayout - Get or compute information about the layout of the
2964 /// specified record (struct/union/class), which indicates its size and field
2965 /// position information.
2966 const ASTRecordLayout &
2968  // These asserts test different things. A record has a definition
2969  // as soon as we begin to parse the definition. That definition is
2970  // not a complete definition (which is what isDefinition() tests)
2971  // until we *finish* parsing the definition.
2972 
2973  if (D->hasExternalLexicalStorage() && !D->getDefinition())
2974  getExternalSource()->CompleteType(const_cast<RecordDecl*>(D));
2975 
2976  D = D->getDefinition();
2977  assert(D && "Cannot get layout of forward declarations!");
2978  assert(!D->isInvalidDecl() && "Cannot get layout of invalid decl!");
2979  assert(D->isCompleteDefinition() && "Cannot layout type before complete!");
2980 
2981  // Look up this layout, if already laid out, return what we have.
2982  // Note that we can't save a reference to the entry because this function
2983  // is recursive.
2984  const ASTRecordLayout *Entry = ASTRecordLayouts[D];
2985  if (Entry) return *Entry;
2986 
2987  const ASTRecordLayout *NewEntry = nullptr;
2988 
2989  if (isMsLayout(*this)) {
2990  MicrosoftRecordLayoutBuilder Builder(*this);
2991  if (const auto *RD = dyn_cast<CXXRecordDecl>(D)) {
2992  Builder.cxxLayout(RD);
2993  NewEntry = new (*this) ASTRecordLayout(
2994  *this, Builder.Size, Builder.Alignment, Builder.Alignment,
2995  Builder.RequiredAlignment,
2996  Builder.HasOwnVFPtr, Builder.HasOwnVFPtr || Builder.PrimaryBase,
2997  Builder.VBPtrOffset, Builder.DataSize, Builder.FieldOffsets,
2998  Builder.NonVirtualSize, Builder.Alignment, CharUnits::Zero(),
2999  Builder.PrimaryBase, false, Builder.SharedVBPtrBase,
3000  Builder.EndsWithZeroSizedObject, Builder.LeadsWithZeroSizedBase,
3001  Builder.Bases, Builder.VBases);
3002  } else {
3003  Builder.layout(D);
3004  NewEntry = new (*this) ASTRecordLayout(
3005  *this, Builder.Size, Builder.Alignment, Builder.Alignment,
3006  Builder.RequiredAlignment,
3007  Builder.Size, Builder.FieldOffsets);
3008  }
3009  } else {
3010  if (const auto *RD = dyn_cast<CXXRecordDecl>(D)) {
3011  EmptySubobjectMap EmptySubobjects(*this, RD);
3012  ItaniumRecordLayoutBuilder Builder(*this, &EmptySubobjects);
3013  Builder.Layout(RD);
3014 
3015  // In certain situations, we are allowed to lay out objects in the
3016  // tail-padding of base classes. This is ABI-dependent.
3017  // FIXME: this should be stored in the record layout.
3018  bool skipTailPadding =
3019  mustSkipTailPadding(getTargetInfo().getCXXABI(), RD);
3020 
3021  // FIXME: This should be done in FinalizeLayout.
3022  CharUnits DataSize =
3023  skipTailPadding ? Builder.getSize() : Builder.getDataSize();
3024  CharUnits NonVirtualSize =
3025  skipTailPadding ? DataSize : Builder.NonVirtualSize;
3026  NewEntry = new (*this) ASTRecordLayout(
3027  *this, Builder.getSize(), Builder.Alignment, Builder.UnadjustedAlignment,
3028  /*RequiredAlignment : used by MS-ABI)*/
3029  Builder.Alignment, Builder.HasOwnVFPtr, RD->isDynamicClass(),
3030  CharUnits::fromQuantity(-1), DataSize, Builder.FieldOffsets,
3031  NonVirtualSize, Builder.NonVirtualAlignment,
3032  EmptySubobjects.SizeOfLargestEmptySubobject, Builder.PrimaryBase,
3033  Builder.PrimaryBaseIsVirtual, nullptr, false, false, Builder.Bases,
3034  Builder.VBases);
3035  } else {
3036  ItaniumRecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
3037  Builder.Layout(D);
3038 
3039  NewEntry = new (*this) ASTRecordLayout(
3040  *this, Builder.getSize(), Builder.Alignment, Builder.UnadjustedAlignment,
3041  /*RequiredAlignment : used by MS-ABI)*/
3042  Builder.Alignment, Builder.getSize(), Builder.FieldOffsets);
3043  }
3044  }
3045 
3046  ASTRecordLayouts[D] = NewEntry;
3047 
3048  if (getLangOpts().DumpRecordLayouts) {
3049  llvm::outs() << "\n*** Dumping AST Record Layout\n";
3050  DumpRecordLayout(D, llvm::outs(), getLangOpts().DumpRecordLayoutsSimple);
3051  }
3052 
3053  return *NewEntry;
3054 }
3055 
3057  if (!getTargetInfo().getCXXABI().hasKeyFunctions())
3058  return nullptr;
3059 
3060  assert(RD->getDefinition() && "Cannot get key function for forward decl!");
3061  RD = RD->getDefinition();
3062 
3063  // Beware:
3064  // 1) computing the key function might trigger deserialization, which might
3065  // invalidate iterators into KeyFunctions
3066  // 2) 'get' on the LazyDeclPtr might also trigger deserialization and
3067  // invalidate the LazyDeclPtr within the map itself
3068  LazyDeclPtr Entry = KeyFunctions[RD];
3069  const Decl *Result =
3070  Entry ? Entry.get(getExternalSource()) : computeKeyFunction(*this, RD);
3071 
3072  // Store it back if it changed.
3073  if (Entry.isOffset() || Entry.isValid() != bool(Result))
3074  KeyFunctions[RD] = const_cast<Decl*>(Result);
3075 
3076  return cast_or_null<CXXMethodDecl>(Result);
3077 }
3078 
3080  assert(Method == Method->getFirstDecl() &&
3081  "not working with method declaration from class definition");
3082 
3083  // Look up the cache entry. Since we're working with the first
3084  // declaration, its parent must be the class definition, which is
3085  // the correct key for the KeyFunctions hash.
3086  const auto &Map = KeyFunctions;
3087  auto I = Map.find(Method->getParent());
3088 
3089  // If it's not cached, there's nothing to do.
3090  if (I == Map.end()) return;
3091 
3092  // If it is cached, check whether it's the target method, and if so,
3093  // remove it from the cache. Note, the call to 'get' might invalidate
3094  // the iterator and the LazyDeclPtr object within the map.
3095  LazyDeclPtr Ptr = I->second;
3096  if (Ptr.get(getExternalSource()) == Method) {
3097  // FIXME: remember that we did this for module / chained PCH state?
3098  KeyFunctions.erase(Method->getParent());
3099  }
3100 }
3101 
3102 static uint64_t getFieldOffset(const ASTContext &C, const FieldDecl *FD) {
3103  const ASTRecordLayout &Layout = C.getASTRecordLayout(FD->getParent());
3104  return Layout.getFieldOffset(FD->getFieldIndex());
3105 }
3106 
3107 uint64_t ASTContext::getFieldOffset(const ValueDecl *VD) const {
3108  uint64_t OffsetInBits;
3109  if (const FieldDecl *FD = dyn_cast<FieldDecl>(VD)) {
3110  OffsetInBits = ::getFieldOffset(*this, FD);
3111  } else {
3112  const IndirectFieldDecl *IFD = cast<IndirectFieldDecl>(VD);
3113 
3114  OffsetInBits = 0;
3115  for (const NamedDecl *ND : IFD->chain())
3116  OffsetInBits += ::getFieldOffset(*this, cast<FieldDecl>(ND));
3117  }
3118 
3119  return OffsetInBits;
3120 }
3121 
3123  const ObjCImplementationDecl *ID,
3124  const ObjCIvarDecl *Ivar) const {
3125  const ObjCInterfaceDecl *Container = Ivar->getContainingInterface();
3126 
3127  // FIXME: We should eliminate the need to have ObjCImplementationDecl passed
3128  // in here; it should never be necessary because that should be the lexical
3129  // decl context for the ivar.
3130 
3131  // If we know have an implementation (and the ivar is in it) then
3132  // look up in the implementation layout.
3133  const ASTRecordLayout *RL;
3134  if (ID && declaresSameEntity(ID->getClassInterface(), Container))
3135  RL = &getASTObjCImplementationLayout(ID);
3136  else
3137  RL = &getASTObjCInterfaceLayout(Container);
3138 
3139  // Compute field index.
3140  //
3141  // FIXME: The index here is closely tied to how ASTContext::getObjCLayout is
3142  // implemented. This should be fixed to get the information from the layout
3143  // directly.
3144  unsigned Index = 0;
3145 
3146  for (const ObjCIvarDecl *IVD = Container->all_declared_ivar_begin();
3147  IVD; IVD = IVD->getNextIvar()) {
3148  if (Ivar == IVD)
3149  break;
3150  ++Index;
3151  }
3152  assert(Index < RL->getFieldCount() && "Ivar is not inside record layout!");
3153 
3154  return RL->getFieldOffset(Index);
3155 }
3156 
3157 /// getObjCLayout - Get or compute information about the layout of the
3158 /// given interface.
3159 ///
3160 /// \param Impl - If given, also include the layout of the interface's
3161 /// implementation. This may differ by including synthesized ivars.
3162 const ASTRecordLayout &
3163 ASTContext::getObjCLayout(const ObjCInterfaceDecl *D,
3164  const ObjCImplementationDecl *Impl) const {
3165  // Retrieve the definition
3166  if (D->hasExternalLexicalStorage() && !D->getDefinition())
3167  getExternalSource()->CompleteType(const_cast<ObjCInterfaceDecl*>(D));
3168  D = D->getDefinition();
3169  assert(D && D->isThisDeclarationADefinition() && "Invalid interface decl!");
3170 
3171  // Look up this layout, if already laid out, return what we have.
3172  const ObjCContainerDecl *Key =
3173  Impl ? (const ObjCContainerDecl*) Impl : (const ObjCContainerDecl*) D;
3174  if (const ASTRecordLayout *Entry = ObjCLayouts[Key])
3175  return *Entry;
3176 
3177  // Add in synthesized ivar count if laying out an implementation.
3178  if (Impl) {
3179  unsigned SynthCount = CountNonClassIvars(D);
3180  // If there aren't any synthesized ivars then reuse the interface
3181  // entry. Note we can't cache this because we simply free all
3182  // entries later; however we shouldn't look up implementations
3183  // frequently.
3184  if (SynthCount == 0)
3185  return getObjCLayout(D, nullptr);
3186  }
3187 
3188  ItaniumRecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
3189  Builder.Layout(D);
3190 
3191  const ASTRecordLayout *NewEntry =
3192  new (*this) ASTRecordLayout(*this, Builder.getSize(),
3193  Builder.Alignment,
3194  Builder.UnadjustedAlignment,
3195  /*RequiredAlignment : used by MS-ABI)*/
3196  Builder.Alignment,
3197  Builder.getDataSize(),
3198  Builder.FieldOffsets);
3199 
3200  ObjCLayouts[Key] = NewEntry;
3201 
3202  return *NewEntry;
3203 }
3204 
3205 static void PrintOffset(raw_ostream &OS,
3206  CharUnits Offset, unsigned IndentLevel) {
3207  OS << llvm::format("%10" PRId64 " | ", (int64_t)Offset.getQuantity());
3208  OS.indent(IndentLevel * 2);
3209 }
3210 
3211 static void PrintBitFieldOffset(raw_ostream &OS, CharUnits Offset,
3212  unsigned Begin, unsigned Width,
3213  unsigned IndentLevel) {
3214  llvm::SmallString<10> Buffer;
3215  {
3216  llvm::raw_svector_ostream BufferOS(Buffer);
3217  BufferOS << Offset.getQuantity() << ':';
3218  if (Width == 0) {
3219  BufferOS << '-';
3220  } else {
3221  BufferOS << Begin << '-' << (Begin + Width - 1);
3222  }
3223  }
3224 
3225  OS << llvm::right_justify(Buffer, 10) << " | ";
3226  OS.indent(IndentLevel * 2);
3227 }
3228 
3229 static void PrintIndentNoOffset(raw_ostream &OS, unsigned IndentLevel) {
3230  OS << " | ";
3231  OS.indent(IndentLevel * 2);
3232 }
3233 
3234 static void DumpRecordLayout(raw_ostream &OS, const RecordDecl *RD,
3235  const ASTContext &C,
3236  CharUnits Offset,
3237  unsigned IndentLevel,
3238  const char* Description,
3239  bool PrintSizeInfo,
3240  bool IncludeVirtualBases) {
3241  const ASTRecordLayout &Layout = C.getASTRecordLayout(RD);
3242  auto CXXRD = dyn_cast<CXXRecordDecl>(RD);
3243 
3244  PrintOffset(OS, Offset, IndentLevel);
3245  OS << C.getTypeDeclType(const_cast<RecordDecl*>(RD)).getAsString();
3246  if (Description)
3247  OS << ' ' << Description;
3248  if (CXXRD && CXXRD->isEmpty())
3249  OS << " (empty)";
3250  OS << '\n';
3251 
3252  IndentLevel++;
3253 
3254  // Dump bases.
3255  if (CXXRD) {
3256  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
3257  bool HasOwnVFPtr = Layout.hasOwnVFPtr();
3258  bool HasOwnVBPtr = Layout.hasOwnVBPtr();
3259 
3260  // Vtable pointer.
3261  if (CXXRD->isDynamicClass() && !PrimaryBase && !isMsLayout(C)) {
3262  PrintOffset(OS, Offset, IndentLevel);
3263  OS << '(' << *RD << " vtable pointer)\n";
3264  } else if (HasOwnVFPtr) {
3265  PrintOffset(OS, Offset, IndentLevel);
3266  // vfptr (for Microsoft C++ ABI)
3267  OS << '(' << *RD << " vftable pointer)\n";
3268  }
3269 
3270  // Collect nvbases.
3272  for (const CXXBaseSpecifier &Base : CXXRD->bases()) {
3273  assert(!Base.getType()->isDependentType() &&
3274  "Cannot layout class with dependent bases.");
3275  if (!Base.isVirtual())
3276  Bases.push_back(Base.getType()->getAsCXXRecordDecl());
3277  }
3278 
3279  // Sort nvbases by offset.
3280  std::stable_sort(Bases.begin(), Bases.end(),
3281  [&](const CXXRecordDecl *L, const CXXRecordDecl *R) {
3282  return Layout.getBaseClassOffset(L) < Layout.getBaseClassOffset(R);
3283  });
3284 
3285  // Dump (non-virtual) bases
3286  for (const CXXRecordDecl *Base : Bases) {
3287  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base);
3288  DumpRecordLayout(OS, Base, C, BaseOffset, IndentLevel,
3289  Base == PrimaryBase ? "(primary base)" : "(base)",
3290  /*PrintSizeInfo=*/false,
3291  /*IncludeVirtualBases=*/false);
3292  }
3293 
3294  // vbptr (for Microsoft C++ ABI)
3295  if (HasOwnVBPtr) {
3296  PrintOffset(OS, Offset + Layout.getVBPtrOffset(), IndentLevel);
3297  OS << '(' << *RD << " vbtable pointer)\n";
3298  }
3299  }
3300 
3301  // Dump fields.
3302  uint64_t FieldNo = 0;
3303  for (RecordDecl::field_iterator I = RD->field_begin(),
3304  E = RD->field_end(); I != E; ++I, ++FieldNo) {
3305  const FieldDecl &Field = **I;
3306  uint64_t LocalFieldOffsetInBits = Layout.getFieldOffset(FieldNo);
3307  CharUnits FieldOffset =
3308  Offset + C.toCharUnitsFromBits(LocalFieldOffsetInBits);
3309 
3310  // Recursively dump fields of record type.
3311  if (auto RT = Field.getType()->getAs<RecordType>()) {
3312  DumpRecordLayout(OS, RT->getDecl(), C, FieldOffset, IndentLevel,
3313  Field.getName().data(),
3314  /*PrintSizeInfo=*/false,
3315  /*IncludeVirtualBases=*/true);
3316  continue;
3317  }
3318 
3319  if (Field.isBitField()) {
3320  uint64_t LocalFieldByteOffsetInBits = C.toBits(FieldOffset - Offset);
3321  unsigned Begin = LocalFieldOffsetInBits - LocalFieldByteOffsetInBits;
3322  unsigned Width = Field.getBitWidthValue(C);
3323  PrintBitFieldOffset(OS, FieldOffset, Begin, Width, IndentLevel);
3324  } else {
3325  PrintOffset(OS, FieldOffset, IndentLevel);
3326  }
3327  OS << Field.getType().getAsString() << ' ' << Field << '\n';
3328  }
3329 
3330  // Dump virtual bases.
3331  if (CXXRD && IncludeVirtualBases) {
3332  const ASTRecordLayout::VBaseOffsetsMapTy &VtorDisps =
3333  Layout.getVBaseOffsetsMap();
3334 
3335  for (const CXXBaseSpecifier &Base : CXXRD->vbases()) {
3336  assert(Base.isVirtual() && "Found non-virtual class!");
3337  const CXXRecordDecl *VBase = Base.getType()->getAsCXXRecordDecl();
3338 
3339  CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBase);
3340 
3341  if (VtorDisps.find(VBase)->second.hasVtorDisp()) {
3342  PrintOffset(OS, VBaseOffset - CharUnits::fromQuantity(4), IndentLevel);
3343  OS << "(vtordisp for vbase " << *VBase << ")\n";
3344  }
3345 
3346  DumpRecordLayout(OS, VBase, C, VBaseOffset, IndentLevel,
3347  VBase == Layout.getPrimaryBase() ?
3348  "(primary virtual base)" : "(virtual base)",
3349  /*PrintSizeInfo=*/false,
3350  /*IncludeVirtualBases=*/false);
3351  }
3352  }
3353 
3354  if (!PrintSizeInfo) return;
3355 
3356  PrintIndentNoOffset(OS, IndentLevel - 1);
3357  OS << "[sizeof=" << Layout.getSize().getQuantity();
3358  if (CXXRD && !isMsLayout(C))
3359  OS << ", dsize=" << Layout.getDataSize().getQuantity();
3360  OS << ", align=" << Layout.getAlignment().getQuantity();
3361 
3362  if (CXXRD) {
3363  OS << ",\n";
3364  PrintIndentNoOffset(OS, IndentLevel - 1);
3365  OS << " nvsize=" << Layout.getNonVirtualSize().getQuantity();
3366  OS << ", nvalign=" << Layout.getNonVirtualAlignment().getQuantity();
3367  }
3368  OS << "]\n";
3369 }
3370 
3372  raw_ostream &OS,
3373  bool Simple) const {
3374  if (!Simple) {
3375  ::DumpRecordLayout(OS, RD, *this, CharUnits(), 0, nullptr,
3376  /*PrintSizeInfo*/true,
3377  /*IncludeVirtualBases=*/true);
3378  return;
3379  }
3380 
3381  // The "simple" format is designed to be parsed by the
3382  // layout-override testing code. There shouldn't be any external
3383  // uses of this format --- when LLDB overrides a layout, it sets up
3384  // the data structures directly --- so feel free to adjust this as
3385  // you like as long as you also update the rudimentary parser for it
3386  // in libFrontend.
3387 
3388  const ASTRecordLayout &Info = getASTRecordLayout(RD);
3389  OS << "Type: " << getTypeDeclType(RD).getAsString() << "\n";
3390  OS << "\nLayout: ";
3391  OS << "<ASTRecordLayout\n";
3392  OS << " Size:" << toBits(Info.getSize()) << "\n";
3393  if (!isMsLayout(*this))
3394  OS << " DataSize:" << toBits(Info.getDataSize()) << "\n";
3395  OS << " Alignment:" << toBits(Info.getAlignment()) << "\n";
3396  OS << " FieldOffsets: [";
3397  for (unsigned i = 0, e = Info.getFieldCount(); i != e; ++i) {
3398  if (i) OS << ", ";
3399  OS << Info.getFieldOffset(i);
3400  }
3401  OS << "]>\n";
3402 }
static uint64_t getFieldOffset(const ASTContext &C, const FieldDecl *FD)
Defines the clang::ASTContext interface.
CharUnits alignTo(const CharUnits &Align) const
alignTo - Returns the next integer (mod 2**64) that is greater than or equal to this quantity and is ...
Definition: CharUnits.h:184
Represents a function declaration or definition.
Definition: Decl.h:1717
Only allocate objects in the tail padding of a base class if the base class is not POD according to t...
Definition: TargetCXXABI.h:302
static DiagnosticBuilder Diag(DiagnosticsEngine *Diags, const LangOptions &Features, FullSourceLoc TokLoc, const char *TokBegin, const char *TokRangeBegin, const char *TokRangeEnd, unsigned DiagID)
Produce a diagnostic highlighting some portion of a literal.
bool isPrimaryBaseVirtual() const
isPrimaryBaseVirtual - Get whether the primary base for this record is virtual or not...
Definition: RecordLayout.h:226
A (possibly-)qualified type.
Definition: Type.h:642
static bool mustSkipTailPadding(TargetCXXABI ABI, const CXXRecordDecl *RD)
Does the target C++ ABI require us to skip over the tail-padding of the given class (considering it a...
static void DumpRecordLayout(raw_ostream &OS, const RecordDecl *RD, const ASTContext &C, CharUnits Offset, unsigned IndentLevel, const char *Description, bool PrintSizeInfo, bool IncludeVirtualBases)
base_class_range bases()
Definition: DeclCXX.h:823
Attempt to be ABI-compatible with code generated by Clang 6.0.x (SVN r321711).
The basic abstraction for the target C++ ABI.
Definition: TargetCXXABI.h:24
bool isThisDeclarationADefinition() const
Determine whether this particular declaration of this class is actually also a definition.
Definition: DeclObjC.h:1522
const ASTRecordLayout & getASTRecordLayout(const RecordDecl *D) const
Get or compute information about the layout of the specified record (struct/union/class) D...
QualType getPointeeType() const
If this is a pointer, ObjC object pointer, or block pointer, this returns the respective pointee...
Definition: Type.cpp:497
const llvm::Triple & getTriple() const
Returns the target triple of the primary target.
Definition: TargetInfo.h:949
CharUnits getBaseClassOffset(const CXXRecordDecl *Base) const
getBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:233
unsigned getNumVBases() const
Retrieves the number of virtual base classes of this class.
Definition: DeclCXX.h:838
Decl - This represents one declaration (or definition), e.g.
Definition: DeclBase.h:86
bool isPOD() const
Whether this class is a POD-type (C++ [class]p4)
Definition: DeclCXX.h:1314
unsigned getFieldIndex() const
Returns the index of this field within its record, as appropriate for passing to ASTRecordLayout::get...
Definition: Decl.cpp:3775
const RecordDecl * getParent() const
Returns the parent of this field declaration, which is the struct in which this field is defined...
Definition: Decl.h:2740
The base class of the type hierarchy.
Definition: Type.h:1415
DiagnosticsEngine & getDiagnostics() const
DiagnosticBuilder Report(SourceLocation Loc, unsigned DiagID)
Issue the message to the client.
Definition: Diagnostic.h:1294
Represents an array type, per C99 6.7.5.2 - Array Declarators.
Definition: Type.h:2786
bool isZero() const
isZero - Test whether the quantity equals zero.
Definition: CharUnits.h:116
const TargetInfo & getTargetInfo() const
Definition: ASTContext.h:699
CharUnits getAlignment() const
getAlignment - Get the record alignment in characters.
Definition: RecordLayout.h:177
unsigned getCharWidth() const
Definition: TargetInfo.h:370
QualType getElementType() const
Definition: Type.h:2821
bool isCompleteDefinition() const
Return true if this decl has its body fully specified.
Definition: Decl.h:3146
bool hasVBPtr() const
hasVBPtr - Does this class have a virtual function table pointer.
Definition: RecordLayout.h:286
const T * getAs() const
Member-template getAs<specific type>&#39;.
Definition: Type.h:6590
unsigned getCharAlign() const
Definition: TargetInfo.h:371
The "__interface" keyword.
Definition: Type.h:4917
bool hasOwnVFPtr() const
hasOwnVFPtr - Does this class provide its own virtual-function table pointer, rather than inheriting ...
Definition: RecordLayout.h:260
bool isInvalidDecl() const
Definition: DeclBase.h:547
unsigned getZeroLengthBitfieldBoundary() const
Get the fixed alignment value in bits for a member that follows a zero length bitfield.
Definition: TargetInfo.h:672
bool mayInsertExtraPadding(bool EmitRemark=false) const
Whether we are allowed to insert extra padding between fields.
Definition: Decl.cpp:4170
IdentifierInfo * getIdentifier() const
Get the identifier that names this declaration, if there is one.
Definition: Decl.h:269
Represents a struct/union/class.
Definition: Decl.h:3570
uint64_t getPointerWidth(unsigned AddrSpace) const
Return the width of pointers on this target, for the specified address space.
Definition: TargetInfo.h:348
bool isEmpty() const
Determine whether this is an empty class in the sense of (C++11 [meta.unary.prop]).
Definition: DeclCXX.h:1329
TargetCXXABI getCXXABI() const
Get the C++ ABI currently in use.
Definition: TargetInfo.h:1018
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:154
RecordDecl * getDefinition() const
Returns the RecordDecl that actually defines this struct/union/class.
Definition: Decl.h:3751
field_range fields() const
Definition: Decl.h:3761
Represents a member of a struct/union/class.
Definition: Decl.h:2556
bool hasUserDeclaredDestructor() const
Determine whether this class has a user-declared destructor.
Definition: DeclCXX.h:1185
static CharUnits Zero()
Zero - Construct a CharUnits quantity of zero.
Definition: CharUnits.h:53
CharUnits getVBaseClassOffset(const CXXRecordDecl *VBase) const
getVBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:241
method_iterator method_begin() const
Method begin iterator.
Definition: DeclCXX.h:871
uint64_t lookupFieldBitOffset(const ObjCInterfaceDecl *OID, const ObjCImplementationDecl *ID, const ObjCIvarDecl *Ivar) const
Get the offset of an ObjCIvarDecl in bits.
const ASTRecordLayout & getASTObjCInterfaceLayout(const ObjCInterfaceDecl *D) const
Get or compute information about the layout of the specified Objective-C interface.
specific_decl_iterator< FieldDecl > field_iterator
Definition: Decl.h:3758
bool canKeyFunctionBeInline() const
Can an out-of-line inline function serve as a key function?
Definition: TargetCXXABI.h:259
uint64_t getConstantArrayElementCount(const ConstantArrayType *CA) const
Return number of constant array elements.
bool isBitField() const
Determines whether this field is a bitfield.
Definition: Decl.h:2634
ObjCContainerDecl - Represents a container for method declarations.
Definition: DeclObjC.h:961
TagKind getTagKind() const
Definition: Decl.h:3220
CharUnits - This is an opaque type for sizes expressed in character units.
Definition: CharUnits.h:38
uint32_t Offset
Definition: CacheTokens.cpp:43
bool endsWithZeroSizedObject() const
Definition: RecordLayout.h:295
ArrayRef< NamedDecl * > chain() const
Definition: Decl.h:2824
unsigned Align
Definition: ASTContext.h:144
field_iterator field_begin() const
Definition: Decl.cpp:4123
unsigned getBitWidthValue(const ASTContext &Ctx) const
Definition: Decl.cpp:3765
bool declaresSameEntity(const Decl *D1, const Decl *D2)
Determine whether two declarations declare the same entity.
Definition: DeclBase.h:1162
const VBaseOffsetsMapTy & getVBaseOffsetsMap() const
Definition: RecordLayout.h:316
bool isAlignmentRequired(const Type *T) const
Determine if the alignment the type has was required using an alignment attribute.
bool useZeroLengthBitfieldAlignment() const
Check whether zero length bitfields should force alignment of the next member.
Definition: TargetInfo.h:666
Represents an ObjC class declaration.
Definition: DeclObjC.h:1164
const Type * getUnqualifiedDesugaredType() const
Return the specified type with any "sugar" removed from the type, removing any typedefs, typeofs, etc., as well as any qualifiers.
Definition: Type.cpp:411
CanQualType UnsignedCharTy
Definition: ASTContext.h:1035
lookup_result lookup(DeclarationName Name) const
lookup - Find the declarations (if any) with the given Name in this context.
Definition: DeclBase.cpp:1566
bool hasAttr() const
Definition: DeclBase.h:536
static CharUnits One()
One - Construct a CharUnits quantity of one.
Definition: CharUnits.h:58
A little helper class used to produce diagnostics.
Definition: Diagnostic.h:1042
CXXRecordDecl * getAsCXXRecordDecl() const
Retrieves the CXXRecordDecl that this type refers to, either because the type is a RecordType or beca...
Definition: Type.cpp:1605
bool isDynamicClass() const
Definition: DeclCXX.h:789
bool useExplicitBitFieldAlignment() const
Check whether explicit bitfield alignment attributes should be.
Definition: TargetInfo.h:678
static void PrintOffset(raw_ostream &OS, CharUnits Offset, unsigned IndentLevel)
TemplateSpecializationKind getTemplateSpecializationKind() const
Determine whether this particular class is a specialization or instantiation of a class template or m...
Definition: DeclCXX.cpp:1604
QuantityType getQuantity() const
getQuantity - Get the raw integer representation of this quantity.
Definition: CharUnits.h:179
ASTRecordLayout - This class contains layout information for one RecordDecl, which is a struct/union/...
Definition: RecordLayout.h:39
bool isMsStruct(const ASTContext &C) const
Get whether or not this is an ms_struct which can be turned on with an attribute, pragma...
Definition: Decl.cpp:4140
bool isInlineSpecified() const
Determine whether the "inline" keyword was specified for this function.
Definition: Decl.h:2319
Represent the declaration of a variable (in which case it is an lvalue) a function (in which case it ...
Definition: Decl.h:636
SourceLocation End
bool isNearlyEmpty(const CXXRecordDecl *RD) const
field_iterator field_end() const
Definition: Decl.h:3764
#define bool
Definition: stdbool.h:31
CharUnits getSizeOfLargestEmptySubobject() const
Definition: RecordLayout.h:248
overridden_method_range overridden_methods() const
Definition: DeclCXX.cpp:2143
CharUnits getTypeAlignInChars(QualType T) const
Return the ABI-specified alignment of a (complete) type T, in characters.
CXXRecordDecl * getDefinition() const
Definition: DeclCXX.h:769
ObjCInterfaceDecl * getSuperClass() const
Definition: DeclObjC.cpp:338
SourceLocation Begin
const CXXRecordDecl * getPrimaryBase() const
getPrimaryBase - Get the primary base for this record.
Definition: RecordLayout.h:218
static CharUnits fromQuantity(QuantityType Quantity)
fromQuantity - Construct a CharUnits quantity from a raw integer type.
Definition: CharUnits.h:63
unsigned getFieldCount() const
getFieldCount - Get the number of fields in the layout.
Definition: RecordLayout.h:187
bool isTrivial() const
Determine whether this class is considered trivial.
Definition: DeclCXX.h:1547
bool isPolymorphic() const
Whether this class is polymorphic (C++ [class.virtual]), which means that the class contains or inher...
Definition: DeclCXX.h:1339
bool hasExtendableVFPtr() const
hasVFPtr - Does this class have a virtual function table pointer that can be extended by a derived cl...
Definition: RecordLayout.h:268
unsigned getMaxAlignment() const
getMaxAlignment - return the maximum alignment specified by attributes on this decl, 0 if there are none.
Definition: DeclBase.cpp:384
method_iterator method_end() const
Method past-the-end iterator.
Definition: DeclCXX.h:876
CharUnits getVBPtrOffset() const
getVBPtrOffset - Get the offset for virtual base table pointer.
Definition: RecordLayout.h:306
const Type * getBaseElementTypeUnsafe() const
Get the base element type of this type, potentially discarding type qualifiers.
Definition: Type.h:6548
CharUnits getRequiredAlignment() const
Definition: RecordLayout.h:291
QualType getTypeDeclType(const TypeDecl *Decl, const TypeDecl *PrevDecl=nullptr) const
Return the unique reference to the type for the specified type declaration.
Definition: ASTContext.h:1402
The result type of a method or function.
This template specialization was implicitly instantiated from a template.
Definition: Specifiers.h:152
void getIndirectPrimaryBases(CXXIndirectPrimaryBaseSet &Bases) const
Get the indirect primary bases for this class.
bool isNull() const
Return true if this QualType doesn&#39;t point to a type yet.
Definition: Type.h:707
decl_type * getFirstDecl()
Return the first declaration of this declaration or itself if this is the only declaration.
Definition: Redeclarable.h:216
static bool recordUsesEBO(const RecordDecl *RD)
RecordDecl * getDecl() const
Definition: Type.h:4263
Abstract interface for external sources of AST nodes.
uint64_t getFieldOffset(unsigned FieldNo) const
getFieldOffset - Get the offset of the given field index, in bits.
Definition: RecordLayout.h:191
static uint64_t roundUpSizeToCharAlignment(uint64_t Size, const ASTContext &Context)
#define false
Definition: stdbool.h:33
The "struct" keyword.
Definition: Type.h:4914
Only allocate objects in the tail padding of a base class if the base class is not POD according to t...
Definition: TargetCXXABI.h:306
Encodes a location in the source.
A set of all the primary bases for a class.
static void PrintIndentNoOffset(raw_ostream &OS, unsigned IndentLevel)
QualType getBaseElementType(const ArrayType *VAT) const
Return the innermost element type of an array type.
Represents a static or instance method of a struct/union/class.
Definition: DeclCXX.h:2043
const ConstantArrayType * getAsConstantArrayType(QualType T) const
Definition: ASTContext.h:2419
const ArrayType * getAsArrayType(QualType T) const
Type Query functions.
bool hasExternalLexicalStorage() const
Whether this DeclContext has external storage containing additional declarations that are lexically i...
Definition: DeclBase.h:2324
This template specialization was instantiated from a template due to an explicit instantiation defini...
Definition: Specifiers.h:164
CharUnits getDataSize() const
getDataSize() - Get the record data size, which is the record size without tail padding, in characters.
Definition: RecordLayout.h:197
bool useBitFieldTypeAlignment() const
Check whether the alignment of bit-field types is respected when laying out structures.
Definition: TargetInfo.h:660
MSVtorDispAttr::Mode getMSVtorDispMode() const
Controls when vtordisps will be emitted if this record is used as a virtual base. ...
static unsigned getPaddingDiagFromTagKind(TagTypeKind Tag)
Get diagnostic select index for tag kind for field padding diagnostic message.
bool hasFlexibleArrayMember() const
Definition: Decl.h:3624
bool isValid() const
Whether this pointer is non-NULL.
ASTContext & operator=(const ASTContext &)=delete
std::pair< CharUnits, CharUnits > getTypeInfoInChars(const Type *T) const
CanQualType UnsignedShortTy
Definition: ASTContext.h:1035
ObjCIvarDecl * getNextIvar()
Definition: DeclObjC.h:1970
CharUnits getNonVirtualAlignment() const
getNonVirtualSize - Get the non-virtual alignment (in chars) of an object, which is the alignment of ...
Definition: RecordLayout.h:211
TagTypeKind
The kind of a tag type.
Definition: Type.h:4912
const ObjCInterfaceDecl * getClassInterface() const
Definition: DeclObjC.h:2432
Dataflow Directional Tag Classes.
CharUnits getSize() const
getSize - Get the record size in characters.
Definition: RecordLayout.h:184
Represents a field injected from an anonymous union/struct into the parent scope. ...
Definition: Decl.h:2802
CanQualType UnsignedLongLongTy
Definition: ASTContext.h:1036
ObjCInterfaceDecl * getDefinition()
Retrieve the definition of this class, or NULL if this class has been forward-declared (with @class) ...
Definition: DeclObjC.h:1541
This template specialization was instantiated from a template due to an explicit instantiation declar...
Definition: Specifiers.h:160
bool hasUserDeclaredConstructor() const
Determine whether this class has any user-declared constructors.
Definition: DeclCXX.h:986
TailPaddingUseRules getTailPaddingUseRules() const
Definition: TargetCXXABI.h:308
bool isCXX11StandardLayout() const
Determine whether this class was standard-layout per C++11 [class]p7, specifically using the C++11 ru...
Definition: DeclCXX.h:1354
static std::string getAsString(SplitQualType split, const PrintingPolicy &Policy)
Definition: Type.h:975
const CXXRecordDecl * getParent() const
Returns the parent of this method declaration, which is the class in which this method is defined...
Definition: DeclCXX.h:2163
void DumpRecordLayout(const RecordDecl *RD, raw_ostream &OS, bool Simple=false) const
const ObjCInterfaceDecl * getContainingInterface() const
Return the class interface that this ivar is logically contained in; this is either the interface whe...
Definition: DeclObjC.cpp:1790
TemplateSpecializationKind
Describes the kind of template specialization that a particular template specialization declaration r...
Definition: Specifiers.h:146
ExternalASTSource * getExternalSource() const
Retrieve a pointer to the external AST source associated with this AST context, if any...
Definition: ASTContext.h:1089
T * get(ExternalASTSource *Source) const
Retrieve the pointer to the AST node that this lazy pointer points to.
specific_decl_iterator - Iterates over a subrange of declarations stored in a DeclContext, providing only those that are of type SpecificDecl (or a class derived from it).
Definition: DeclBase.h:2029
All virtual base related information about a given record decl.
ObjCImplementationDecl - Represents a class definition - this is where method definitions are specifi...
Definition: DeclObjC.h:2544
bool isIncompleteArrayType() const
Definition: Type.h:6234
A helper class that allows the use of isa/cast/dyncast to detect TagType objects of structs/unions/cl...
Definition: Type.h:4253
CanQualType UnsignedLongTy
Definition: ASTContext.h:1035
static bool RequiresVtordisp(const llvm::SmallPtrSetImpl< const CXXRecordDecl *> &BasesWithOverriddenMethods, const CXXRecordDecl *RD)
T * getAttr() const
Definition: DeclBase.h:532
uint64_t getCharWidth() const
Return the size of the character type, in bits.
Definition: ASTContext.h:2080
void setNonKeyFunction(const CXXMethodDecl *method)
Observe that the given method cannot be a key function.
Base for LValueReferenceType and RValueReferenceType.
Definition: Type.h:2647
The "class" keyword.
Definition: Type.h:4923
Represents a base class of a C++ class.
Definition: DeclCXX.h:192
uint64_t getTypeSize(QualType T) const
Return the size of the specified (complete) type T, in bits.
Definition: ASTContext.h:2076
uint64_t getFieldOffset(const ValueDecl *FD) const
Get the offset of a FieldDecl or IndirectFieldDecl, in bits.
CharUnits toCharUnitsFromBits(int64_t BitSize) const
Convert a size in bits to a size in characters.
Defines the C++ Decl subclasses, other than those for templates (found in DeclTemplate.h) and friends (in DeclFriend.h).
int64_t toBits(CharUnits CharSize) const
Convert a size in characters to a size in bits.
const CXXMethodDecl * getCurrentKeyFunction(const CXXRecordDecl *RD)
Get our current best idea for the key function of the given record decl, or nullptr if there isn&#39;t on...
Represents a C++ struct/union/class.
Definition: DeclCXX.h:300
TypeInfo getTypeInfo(const Type *T) const
Get the size and alignment of the specified complete type in bits.
ObjCIvarDecl - Represents an ObjC instance variable.
Definition: DeclObjC.h:1937
CharUnits getNonVirtualSize() const
getNonVirtualSize - Get the non-virtual size (in chars) of an object, which is the size of the object...
Definition: RecordLayout.h:203
static bool isMsLayout(const ASTContext &Context)
static unsigned getCharWidth(tok::TokenKind kind, const TargetInfo &Target)
This class is used for builtin types like &#39;int&#39;.
Definition: Type.h:2368
static const CXXMethodDecl * computeKeyFunction(ASTContext &Context, const CXXRecordDecl *RD)
The tail-padding of a base class is always theoretically available, even if it&#39;s POD.
Definition: TargetCXXABI.h:297
llvm::DenseMap< const CXXRecordDecl *, VBaseInfo > VBaseOffsetsMapTy
Definition: RecordLayout.h:60
bool isOffset() const
Whether this pointer is currently stored as an offset.
uint64_t getPointerAlign(unsigned AddrSpace) const
Definition: TargetInfo.h:351
Defines the clang::TargetInfo interface.
bool isMicrosoft() const
Is this ABI an MSVC-compatible ABI?
Definition: TargetCXXABI.h:154
StringRef getName() const
Get the name of identifier for this declaration as a StringRef.
Definition: Decl.h:275
static void PrintBitFieldOffset(raw_ostream &OS, CharUnits Offset, unsigned Begin, unsigned Width, unsigned IndentLevel)
uint64_t Width
Definition: ASTContext.h:143
__DEVICE__ int max(int __a, int __b)
bool isUnion() const
Definition: Decl.h:3229
__DEVICE__ int min(int __a, int __b)
CharUnits getTypeSizeInChars(QualType T) const
Return the size of the specified (complete) type T, in characters.
QualType getType() const
Definition: Decl.h:647
This represents a decl that may have a name.
Definition: Decl.h:248
ObjCIvarDecl * all_declared_ivar_begin()
all_declared_ivar_begin - return first ivar declared in this class, its extensions and its implementa...
Definition: DeclObjC.cpp:1592
bool hasOwnVBPtr() const
hasOwnVBPtr - Does this class provide its own virtual-base table pointer, rather than inheriting one ...
Definition: RecordLayout.h:280
unsigned getTargetAddressSpace(QualType T) const
Definition: ASTContext.h:2505
const LangOptions & getLangOpts() const
Definition: ASTContext.h:716
Represents the canonical version of C arrays with a specified constant size.
Definition: Type.h:2846
base_class_range vbases()
Definition: DeclCXX.h:840
SourceLocation getLocation() const
Definition: DeclBase.h:417
bool isExternallyVisible() const
Definition: Decl.h:379
CanQualType UnsignedIntTy
Definition: ASTContext.h:1035
bool leadsWithZeroSizedBase() const
Definition: RecordLayout.h:299
method_range methods() const
Definition: DeclCXX.h:865