clang  6.0.0svn
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 /// \brief 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  /// \brief Overall record size in bits.
64  uint64_t Size;
65 
66  /// \brief Overall record alignment in bits.
67  uint64_t Align;
68 
69  /// \brief Record field offsets in bits.
70  llvm::DenseMap<const FieldDecl *, uint64_t> FieldOffsets;
71 
72  /// \brief Direct, non-virtual base offsets.
73  llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsets;
74 
75  /// \brief 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  /// \brief The alignment if attribute packed is not used.
583  CharUnits UnpackedAlignment;
584 
585  SmallVector<uint64_t, 16> FieldOffsets;
586 
587  /// \brief Whether the external AST source has provided a layout for this
588  /// record.
589  unsigned UseExternalLayout : 1;
590 
591  /// \brief Whether we need to infer alignment, even when we have an
592  /// externally-provided layout.
593  unsigned InferAlignment : 1;
594 
595  /// Packed - Whether the record is packed or not.
596  unsigned Packed : 1;
597 
598  unsigned IsUnion : 1;
599 
600  unsigned IsMac68kAlign : 1;
601 
602  unsigned IsMsStruct : 1;
603 
604  /// UnfilledBitsInLastUnit - If the last field laid out was a bitfield,
605  /// this contains the number of bits in the last unit that can be used for
606  /// an adjacent bitfield if necessary. The unit in question is usually
607  /// a byte, but larger units are used if IsMsStruct.
608  unsigned char UnfilledBitsInLastUnit;
609  /// LastBitfieldTypeSize - If IsMsStruct, represents the size of the type
610  /// of the previous field if it was a bitfield.
611  unsigned char LastBitfieldTypeSize;
612 
613  /// MaxFieldAlignment - The maximum allowed field alignment. This is set by
614  /// #pragma pack.
615  CharUnits MaxFieldAlignment;
616 
617  /// DataSize - The data size of the record being laid out.
618  uint64_t DataSize;
619 
620  CharUnits NonVirtualSize;
621  CharUnits NonVirtualAlignment;
622 
623  /// PrimaryBase - the primary base class (if one exists) of the class
624  /// we're laying out.
625  const CXXRecordDecl *PrimaryBase;
626 
627  /// PrimaryBaseIsVirtual - Whether the primary base of the class we're laying
628  /// out is virtual.
629  bool PrimaryBaseIsVirtual;
630 
631  /// HasOwnVFPtr - Whether the class provides its own vtable/vftbl
632  /// pointer, as opposed to inheriting one from a primary base class.
633  bool HasOwnVFPtr;
634 
635  /// \brief the flag of field offset changing due to packed attribute.
636  bool HasPackedField;
637 
638  typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
639 
640  /// Bases - base classes and their offsets in the record.
641  BaseOffsetsMapTy Bases;
642 
643  // VBases - virtual base classes and their offsets in the record.
645 
646  /// IndirectPrimaryBases - Virtual base classes, direct or indirect, that are
647  /// primary base classes for some other direct or indirect base class.
648  CXXIndirectPrimaryBaseSet IndirectPrimaryBases;
649 
650  /// FirstNearlyEmptyVBase - The first nearly empty virtual base class in
651  /// inheritance graph order. Used for determining the primary base class.
652  const CXXRecordDecl *FirstNearlyEmptyVBase;
653 
654  /// VisitedVirtualBases - A set of all the visited virtual bases, used to
655  /// avoid visiting virtual bases more than once.
656  llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBases;
657 
658  /// Valid if UseExternalLayout is true.
659  ExternalLayout External;
660 
661  ItaniumRecordLayoutBuilder(const ASTContext &Context,
662  EmptySubobjectMap *EmptySubobjects)
663  : Context(Context), EmptySubobjects(EmptySubobjects), Size(0),
664  Alignment(CharUnits::One()), UnpackedAlignment(CharUnits::One()),
665  UseExternalLayout(false), InferAlignment(false), Packed(false),
666  IsUnion(false), IsMac68kAlign(false), IsMsStruct(false),
667  UnfilledBitsInLastUnit(0), LastBitfieldTypeSize(0),
668  MaxFieldAlignment(CharUnits::Zero()), DataSize(0),
669  NonVirtualSize(CharUnits::Zero()),
670  NonVirtualAlignment(CharUnits::One()), PrimaryBase(nullptr),
671  PrimaryBaseIsVirtual(false), HasOwnVFPtr(false),
672  HasPackedField(false), FirstNearlyEmptyVBase(nullptr) {}
673 
674  void Layout(const RecordDecl *D);
675  void Layout(const CXXRecordDecl *D);
676  void Layout(const ObjCInterfaceDecl *D);
677 
678  void LayoutFields(const RecordDecl *D);
679  void LayoutField(const FieldDecl *D, bool InsertExtraPadding);
680  void LayoutWideBitField(uint64_t FieldSize, uint64_t TypeSize,
681  bool FieldPacked, const FieldDecl *D);
682  void LayoutBitField(const FieldDecl *D);
683 
684  TargetCXXABI getCXXABI() const {
685  return Context.getTargetInfo().getCXXABI();
686  }
687 
688  /// BaseSubobjectInfoAllocator - Allocator for BaseSubobjectInfo objects.
689  llvm::SpecificBumpPtrAllocator<BaseSubobjectInfo> BaseSubobjectInfoAllocator;
690 
691  typedef llvm::DenseMap<const CXXRecordDecl *, BaseSubobjectInfo *>
692  BaseSubobjectInfoMapTy;
693 
694  /// VirtualBaseInfo - Map from all the (direct or indirect) virtual bases
695  /// of the class we're laying out to their base subobject info.
696  BaseSubobjectInfoMapTy VirtualBaseInfo;
697 
698  /// NonVirtualBaseInfo - Map from all the direct non-virtual bases of the
699  /// class we're laying out to their base subobject info.
700  BaseSubobjectInfoMapTy NonVirtualBaseInfo;
701 
702  /// ComputeBaseSubobjectInfo - Compute the base subobject information for the
703  /// bases of the given class.
704  void ComputeBaseSubobjectInfo(const CXXRecordDecl *RD);
705 
706  /// ComputeBaseSubobjectInfo - Compute the base subobject information for a
707  /// single class and all of its base classes.
708  BaseSubobjectInfo *ComputeBaseSubobjectInfo(const CXXRecordDecl *RD,
709  bool IsVirtual,
710  BaseSubobjectInfo *Derived);
711 
712  /// DeterminePrimaryBase - Determine the primary base of the given class.
713  void DeterminePrimaryBase(const CXXRecordDecl *RD);
714 
715  void SelectPrimaryVBase(const CXXRecordDecl *RD);
716 
717  void EnsureVTablePointerAlignment(CharUnits UnpackedBaseAlign);
718 
719  /// LayoutNonVirtualBases - Determines the primary base class (if any) and
720  /// lays it out. Will then proceed to lay out all non-virtual base clasess.
721  void LayoutNonVirtualBases(const CXXRecordDecl *RD);
722 
723  /// LayoutNonVirtualBase - Lays out a single non-virtual base.
724  void LayoutNonVirtualBase(const BaseSubobjectInfo *Base);
725 
726  void AddPrimaryVirtualBaseOffsets(const BaseSubobjectInfo *Info,
727  CharUnits Offset);
728 
729  /// LayoutVirtualBases - Lays out all the virtual bases.
730  void LayoutVirtualBases(const CXXRecordDecl *RD,
731  const CXXRecordDecl *MostDerivedClass);
732 
733  /// LayoutVirtualBase - Lays out a single virtual base.
734  void LayoutVirtualBase(const BaseSubobjectInfo *Base);
735 
736  /// LayoutBase - Will lay out a base and return the offset where it was
737  /// placed, in chars.
738  CharUnits LayoutBase(const BaseSubobjectInfo *Base);
739 
740  /// InitializeLayout - Initialize record layout for the given record decl.
741  void InitializeLayout(const Decl *D);
742 
743  /// FinishLayout - Finalize record layout. Adjust record size based on the
744  /// alignment.
745  void FinishLayout(const NamedDecl *D);
746 
747  void UpdateAlignment(CharUnits NewAlignment, CharUnits UnpackedNewAlignment);
748  void UpdateAlignment(CharUnits NewAlignment) {
749  UpdateAlignment(NewAlignment, NewAlignment);
750  }
751 
752  /// \brief Retrieve the externally-supplied field offset for the given
753  /// field.
754  ///
755  /// \param Field The field whose offset is being queried.
756  /// \param ComputedOffset The offset that we've computed for this field.
757  uint64_t updateExternalFieldOffset(const FieldDecl *Field,
758  uint64_t ComputedOffset);
759 
760  void CheckFieldPadding(uint64_t Offset, uint64_t UnpaddedOffset,
761  uint64_t UnpackedOffset, unsigned UnpackedAlign,
762  bool isPacked, const FieldDecl *D);
763 
764  DiagnosticBuilder Diag(SourceLocation Loc, unsigned DiagID);
765 
766  CharUnits getSize() const {
767  assert(Size % Context.getCharWidth() == 0);
768  return Context.toCharUnitsFromBits(Size);
769  }
770  uint64_t getSizeInBits() const { return Size; }
771 
772  void setSize(CharUnits NewSize) { Size = Context.toBits(NewSize); }
773  void setSize(uint64_t NewSize) { Size = NewSize; }
774 
775  CharUnits getAligment() const { return Alignment; }
776 
777  CharUnits getDataSize() const {
778  assert(DataSize % Context.getCharWidth() == 0);
779  return Context.toCharUnitsFromBits(DataSize);
780  }
781  uint64_t getDataSizeInBits() const { return DataSize; }
782 
783  void setDataSize(CharUnits NewSize) { DataSize = Context.toBits(NewSize); }
784  void setDataSize(uint64_t NewSize) { DataSize = NewSize; }
785 
786  ItaniumRecordLayoutBuilder(const ItaniumRecordLayoutBuilder &) = delete;
787  void operator=(const ItaniumRecordLayoutBuilder &) = delete;
788 };
789 } // end anonymous namespace
790 
791 void ItaniumRecordLayoutBuilder::SelectPrimaryVBase(const CXXRecordDecl *RD) {
792  for (const auto &I : RD->bases()) {
793  assert(!I.getType()->isDependentType() &&
794  "Cannot layout class with dependent bases.");
795 
796  const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();
797 
798  // Check if this is a nearly empty virtual base.
799  if (I.isVirtual() && Context.isNearlyEmpty(Base)) {
800  // If it's not an indirect primary base, then we've found our primary
801  // base.
802  if (!IndirectPrimaryBases.count(Base)) {
803  PrimaryBase = Base;
804  PrimaryBaseIsVirtual = true;
805  return;
806  }
807 
808  // Is this the first nearly empty virtual base?
809  if (!FirstNearlyEmptyVBase)
810  FirstNearlyEmptyVBase = Base;
811  }
812 
813  SelectPrimaryVBase(Base);
814  if (PrimaryBase)
815  return;
816  }
817 }
818 
819 /// DeterminePrimaryBase - Determine the primary base of the given class.
820 void ItaniumRecordLayoutBuilder::DeterminePrimaryBase(const CXXRecordDecl *RD) {
821  // If the class isn't dynamic, it won't have a primary base.
822  if (!RD->isDynamicClass())
823  return;
824 
825  // Compute all the primary virtual bases for all of our direct and
826  // indirect bases, and record all their primary virtual base classes.
827  RD->getIndirectPrimaryBases(IndirectPrimaryBases);
828 
829  // If the record has a dynamic base class, attempt to choose a primary base
830  // class. It is the first (in direct base class order) non-virtual dynamic
831  // base class, if one exists.
832  for (const auto &I : RD->bases()) {
833  // Ignore virtual bases.
834  if (I.isVirtual())
835  continue;
836 
837  const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();
838 
839  if (Base->isDynamicClass()) {
840  // We found it.
841  PrimaryBase = Base;
842  PrimaryBaseIsVirtual = false;
843  return;
844  }
845  }
846 
847  // Under the Itanium ABI, if there is no non-virtual primary base class,
848  // try to compute the primary virtual base. The primary virtual base is
849  // the first nearly empty virtual base that is not an indirect primary
850  // virtual base class, if one exists.
851  if (RD->getNumVBases() != 0) {
852  SelectPrimaryVBase(RD);
853  if (PrimaryBase)
854  return;
855  }
856 
857  // Otherwise, it is the first indirect primary base class, if one exists.
858  if (FirstNearlyEmptyVBase) {
859  PrimaryBase = FirstNearlyEmptyVBase;
860  PrimaryBaseIsVirtual = true;
861  return;
862  }
863 
864  assert(!PrimaryBase && "Should not get here with a primary base!");
865 }
866 
867 BaseSubobjectInfo *ItaniumRecordLayoutBuilder::ComputeBaseSubobjectInfo(
868  const CXXRecordDecl *RD, bool IsVirtual, BaseSubobjectInfo *Derived) {
869  BaseSubobjectInfo *Info;
870 
871  if (IsVirtual) {
872  // Check if we already have info about this virtual base.
873  BaseSubobjectInfo *&InfoSlot = VirtualBaseInfo[RD];
874  if (InfoSlot) {
875  assert(InfoSlot->Class == RD && "Wrong class for virtual base info!");
876  return InfoSlot;
877  }
878 
879  // We don't, create it.
880  InfoSlot = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
881  Info = InfoSlot;
882  } else {
883  Info = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
884  }
885 
886  Info->Class = RD;
887  Info->IsVirtual = IsVirtual;
888  Info->Derived = nullptr;
889  Info->PrimaryVirtualBaseInfo = nullptr;
890 
891  const CXXRecordDecl *PrimaryVirtualBase = nullptr;
892  BaseSubobjectInfo *PrimaryVirtualBaseInfo = nullptr;
893 
894  // Check if this base has a primary virtual base.
895  if (RD->getNumVBases()) {
896  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
897  if (Layout.isPrimaryBaseVirtual()) {
898  // This base does have a primary virtual base.
899  PrimaryVirtualBase = Layout.getPrimaryBase();
900  assert(PrimaryVirtualBase && "Didn't have a primary virtual base!");
901 
902  // Now check if we have base subobject info about this primary base.
903  PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
904 
905  if (PrimaryVirtualBaseInfo) {
906  if (PrimaryVirtualBaseInfo->Derived) {
907  // We did have info about this primary base, and it turns out that it
908  // has already been claimed as a primary virtual base for another
909  // base.
910  PrimaryVirtualBase = nullptr;
911  } else {
912  // We can claim this base as our primary base.
913  Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
914  PrimaryVirtualBaseInfo->Derived = Info;
915  }
916  }
917  }
918  }
919 
920  // Now go through all direct bases.
921  for (const auto &I : RD->bases()) {
922  bool IsVirtual = I.isVirtual();
923 
924  const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
925 
926  Info->Bases.push_back(ComputeBaseSubobjectInfo(BaseDecl, IsVirtual, Info));
927  }
928 
929  if (PrimaryVirtualBase && !PrimaryVirtualBaseInfo) {
930  // Traversing the bases must have created the base info for our primary
931  // virtual base.
932  PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
933  assert(PrimaryVirtualBaseInfo &&
934  "Did not create a primary virtual base!");
935 
936  // Claim the primary virtual base as our primary virtual base.
937  Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
938  PrimaryVirtualBaseInfo->Derived = Info;
939  }
940 
941  return Info;
942 }
943 
944 void ItaniumRecordLayoutBuilder::ComputeBaseSubobjectInfo(
945  const CXXRecordDecl *RD) {
946  for (const auto &I : RD->bases()) {
947  bool IsVirtual = I.isVirtual();
948 
949  const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
950 
951  // Compute the base subobject info for this base.
952  BaseSubobjectInfo *Info = ComputeBaseSubobjectInfo(BaseDecl, IsVirtual,
953  nullptr);
954 
955  if (IsVirtual) {
956  // ComputeBaseInfo has already added this base for us.
957  assert(VirtualBaseInfo.count(BaseDecl) &&
958  "Did not add virtual base!");
959  } else {
960  // Add the base info to the map of non-virtual bases.
961  assert(!NonVirtualBaseInfo.count(BaseDecl) &&
962  "Non-virtual base already exists!");
963  NonVirtualBaseInfo.insert(std::make_pair(BaseDecl, Info));
964  }
965  }
966 }
967 
968 void ItaniumRecordLayoutBuilder::EnsureVTablePointerAlignment(
969  CharUnits UnpackedBaseAlign) {
970  CharUnits BaseAlign = (Packed) ? CharUnits::One() : UnpackedBaseAlign;
971 
972  // The maximum field alignment overrides base align.
973  if (!MaxFieldAlignment.isZero()) {
974  BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
975  UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
976  }
977 
978  // Round up the current record size to pointer alignment.
979  setSize(getSize().alignTo(BaseAlign));
980  setDataSize(getSize());
981 
982  // Update the alignment.
983  UpdateAlignment(BaseAlign, UnpackedBaseAlign);
984 }
985 
986 void ItaniumRecordLayoutBuilder::LayoutNonVirtualBases(
987  const CXXRecordDecl *RD) {
988  // Then, determine the primary base class.
989  DeterminePrimaryBase(RD);
990 
991  // Compute base subobject info.
992  ComputeBaseSubobjectInfo(RD);
993 
994  // If we have a primary base class, lay it out.
995  if (PrimaryBase) {
996  if (PrimaryBaseIsVirtual) {
997  // If the primary virtual base was a primary virtual base of some other
998  // base class we'll have to steal it.
999  BaseSubobjectInfo *PrimaryBaseInfo = VirtualBaseInfo.lookup(PrimaryBase);
1000  PrimaryBaseInfo->Derived = nullptr;
1001 
1002  // We have a virtual primary base, insert it as an indirect primary base.
1003  IndirectPrimaryBases.insert(PrimaryBase);
1004 
1005  assert(!VisitedVirtualBases.count(PrimaryBase) &&
1006  "vbase already visited!");
1007  VisitedVirtualBases.insert(PrimaryBase);
1008 
1009  LayoutVirtualBase(PrimaryBaseInfo);
1010  } else {
1011  BaseSubobjectInfo *PrimaryBaseInfo =
1012  NonVirtualBaseInfo.lookup(PrimaryBase);
1013  assert(PrimaryBaseInfo &&
1014  "Did not find base info for non-virtual primary base!");
1015 
1016  LayoutNonVirtualBase(PrimaryBaseInfo);
1017  }
1018 
1019  // If this class needs a vtable/vf-table and didn't get one from a
1020  // primary base, add it in now.
1021  } else if (RD->isDynamicClass()) {
1022  assert(DataSize == 0 && "Vtable pointer must be at offset zero!");
1023  CharUnits PtrWidth =
1024  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
1025  CharUnits PtrAlign =
1026  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
1027  EnsureVTablePointerAlignment(PtrAlign);
1028  HasOwnVFPtr = true;
1029  setSize(getSize() + PtrWidth);
1030  setDataSize(getSize());
1031  }
1032 
1033  // Now lay out the non-virtual bases.
1034  for (const auto &I : RD->bases()) {
1035 
1036  // Ignore virtual bases.
1037  if (I.isVirtual())
1038  continue;
1039 
1040  const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
1041 
1042  // Skip the primary base, because we've already laid it out. The
1043  // !PrimaryBaseIsVirtual check is required because we might have a
1044  // non-virtual base of the same type as a primary virtual base.
1045  if (BaseDecl == PrimaryBase && !PrimaryBaseIsVirtual)
1046  continue;
1047 
1048  // Lay out the base.
1049  BaseSubobjectInfo *BaseInfo = NonVirtualBaseInfo.lookup(BaseDecl);
1050  assert(BaseInfo && "Did not find base info for non-virtual base!");
1051 
1052  LayoutNonVirtualBase(BaseInfo);
1053  }
1054 }
1055 
1056 void ItaniumRecordLayoutBuilder::LayoutNonVirtualBase(
1057  const BaseSubobjectInfo *Base) {
1058  // Layout the base.
1059  CharUnits Offset = LayoutBase(Base);
1060 
1061  // Add its base class offset.
1062  assert(!Bases.count(Base->Class) && "base offset already exists!");
1063  Bases.insert(std::make_pair(Base->Class, Offset));
1064 
1065  AddPrimaryVirtualBaseOffsets(Base, Offset);
1066 }
1067 
1068 void ItaniumRecordLayoutBuilder::AddPrimaryVirtualBaseOffsets(
1069  const BaseSubobjectInfo *Info, CharUnits Offset) {
1070  // This base isn't interesting, it has no virtual bases.
1071  if (!Info->Class->getNumVBases())
1072  return;
1073 
1074  // First, check if we have a virtual primary base to add offsets for.
1075  if (Info->PrimaryVirtualBaseInfo) {
1076  assert(Info->PrimaryVirtualBaseInfo->IsVirtual &&
1077  "Primary virtual base is not virtual!");
1078  if (Info->PrimaryVirtualBaseInfo->Derived == Info) {
1079  // Add the offset.
1080  assert(!VBases.count(Info->PrimaryVirtualBaseInfo->Class) &&
1081  "primary vbase offset already exists!");
1082  VBases.insert(std::make_pair(Info->PrimaryVirtualBaseInfo->Class,
1083  ASTRecordLayout::VBaseInfo(Offset, false)));
1084 
1085  // Traverse the primary virtual base.
1086  AddPrimaryVirtualBaseOffsets(Info->PrimaryVirtualBaseInfo, Offset);
1087  }
1088  }
1089 
1090  // Now go through all direct non-virtual bases.
1091  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
1092  for (const BaseSubobjectInfo *Base : Info->Bases) {
1093  if (Base->IsVirtual)
1094  continue;
1095 
1096  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
1097  AddPrimaryVirtualBaseOffsets(Base, BaseOffset);
1098  }
1099 }
1100 
1101 void ItaniumRecordLayoutBuilder::LayoutVirtualBases(
1102  const CXXRecordDecl *RD, const CXXRecordDecl *MostDerivedClass) {
1103  const CXXRecordDecl *PrimaryBase;
1104  bool PrimaryBaseIsVirtual;
1105 
1106  if (MostDerivedClass == RD) {
1107  PrimaryBase = this->PrimaryBase;
1108  PrimaryBaseIsVirtual = this->PrimaryBaseIsVirtual;
1109  } else {
1110  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1111  PrimaryBase = Layout.getPrimaryBase();
1112  PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual();
1113  }
1114 
1115  for (const CXXBaseSpecifier &Base : RD->bases()) {
1116  assert(!Base.getType()->isDependentType() &&
1117  "Cannot layout class with dependent bases.");
1118 
1119  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1120 
1121  if (Base.isVirtual()) {
1122  if (PrimaryBase != BaseDecl || !PrimaryBaseIsVirtual) {
1123  bool IndirectPrimaryBase = IndirectPrimaryBases.count(BaseDecl);
1124 
1125  // Only lay out the virtual base if it's not an indirect primary base.
1126  if (!IndirectPrimaryBase) {
1127  // Only visit virtual bases once.
1128  if (!VisitedVirtualBases.insert(BaseDecl).second)
1129  continue;
1130 
1131  const BaseSubobjectInfo *BaseInfo = VirtualBaseInfo.lookup(BaseDecl);
1132  assert(BaseInfo && "Did not find virtual base info!");
1133  LayoutVirtualBase(BaseInfo);
1134  }
1135  }
1136  }
1137 
1138  if (!BaseDecl->getNumVBases()) {
1139  // This base isn't interesting since it doesn't have any virtual bases.
1140  continue;
1141  }
1142 
1143  LayoutVirtualBases(BaseDecl, MostDerivedClass);
1144  }
1145 }
1146 
1147 void ItaniumRecordLayoutBuilder::LayoutVirtualBase(
1148  const BaseSubobjectInfo *Base) {
1149  assert(!Base->Derived && "Trying to lay out a primary virtual base!");
1150 
1151  // Layout the base.
1152  CharUnits Offset = LayoutBase(Base);
1153 
1154  // Add its base class offset.
1155  assert(!VBases.count(Base->Class) && "vbase offset already exists!");
1156  VBases.insert(std::make_pair(Base->Class,
1157  ASTRecordLayout::VBaseInfo(Offset, false)));
1158 
1159  AddPrimaryVirtualBaseOffsets(Base, Offset);
1160 }
1161 
1162 CharUnits
1163 ItaniumRecordLayoutBuilder::LayoutBase(const BaseSubobjectInfo *Base) {
1164  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base->Class);
1165 
1166 
1167  CharUnits Offset;
1168 
1169  // Query the external layout to see if it provides an offset.
1170  bool HasExternalLayout = false;
1171  if (UseExternalLayout) {
1172  if (Base->IsVirtual)
1173  HasExternalLayout = External.getExternalNVBaseOffset(Base->Class, Offset);
1174  else
1175  HasExternalLayout = External.getExternalVBaseOffset(Base->Class, Offset);
1176  }
1177 
1178  CharUnits UnpackedBaseAlign = Layout.getNonVirtualAlignment();
1179  CharUnits BaseAlign = (Packed) ? CharUnits::One() : UnpackedBaseAlign;
1180 
1181  // If we have an empty base class, try to place it at offset 0.
1182  if (Base->Class->isEmpty() &&
1183  (!HasExternalLayout || Offset == CharUnits::Zero()) &&
1184  EmptySubobjects->CanPlaceBaseAtOffset(Base, CharUnits::Zero())) {
1185  setSize(std::max(getSize(), Layout.getSize()));
1186  UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1187 
1188  return CharUnits::Zero();
1189  }
1190 
1191  // The maximum field alignment overrides base align.
1192  if (!MaxFieldAlignment.isZero()) {
1193  BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
1194  UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
1195  }
1196 
1197  if (!HasExternalLayout) {
1198  // Round up the current record size to the base's alignment boundary.
1199  Offset = getDataSize().alignTo(BaseAlign);
1200 
1201  // Try to place the base.
1202  while (!EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset))
1203  Offset += BaseAlign;
1204  } else {
1205  bool Allowed = EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset);
1206  (void)Allowed;
1207  assert(Allowed && "Base subobject externally placed at overlapping offset");
1208 
1209  if (InferAlignment && Offset < getDataSize().alignTo(BaseAlign)) {
1210  // The externally-supplied base offset is before the base offset we
1211  // computed. Assume that the structure is packed.
1212  Alignment = CharUnits::One();
1213  InferAlignment = false;
1214  }
1215  }
1216 
1217  if (!Base->Class->isEmpty()) {
1218  // Update the data size.
1219  setDataSize(Offset + Layout.getNonVirtualSize());
1220 
1221  setSize(std::max(getSize(), getDataSize()));
1222  } else
1223  setSize(std::max(getSize(), Offset + Layout.getSize()));
1224 
1225  // Remember max struct/class alignment.
1226  UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1227 
1228  return Offset;
1229 }
1230 
1231 void ItaniumRecordLayoutBuilder::InitializeLayout(const Decl *D) {
1232  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
1233  IsUnion = RD->isUnion();
1234  IsMsStruct = RD->isMsStruct(Context);
1235  }
1236 
1237  Packed = D->hasAttr<PackedAttr>();
1238 
1239  // Honor the default struct packing maximum alignment flag.
1240  if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct) {
1241  MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
1242  }
1243 
1244  // mac68k alignment supersedes maximum field alignment and attribute aligned,
1245  // and forces all structures to have 2-byte alignment. The IBM docs on it
1246  // allude to additional (more complicated) semantics, especially with regard
1247  // to bit-fields, but gcc appears not to follow that.
1248  if (D->hasAttr<AlignMac68kAttr>()) {
1249  IsMac68kAlign = true;
1250  MaxFieldAlignment = CharUnits::fromQuantity(2);
1251  Alignment = CharUnits::fromQuantity(2);
1252  } else {
1253  if (const MaxFieldAlignmentAttr *MFAA = D->getAttr<MaxFieldAlignmentAttr>())
1254  MaxFieldAlignment = Context.toCharUnitsFromBits(MFAA->getAlignment());
1255 
1256  if (unsigned MaxAlign = D->getMaxAlignment())
1257  UpdateAlignment(Context.toCharUnitsFromBits(MaxAlign));
1258  }
1259 
1260  // If there is an external AST source, ask it for the various offsets.
1261  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D))
1262  if (ExternalASTSource *Source = Context.getExternalSource()) {
1263  UseExternalLayout = Source->layoutRecordType(
1264  RD, External.Size, External.Align, External.FieldOffsets,
1265  External.BaseOffsets, External.VirtualBaseOffsets);
1266 
1267  // Update based on external alignment.
1268  if (UseExternalLayout) {
1269  if (External.Align > 0) {
1270  Alignment = Context.toCharUnitsFromBits(External.Align);
1271  } else {
1272  // The external source didn't have alignment information; infer it.
1273  InferAlignment = true;
1274  }
1275  }
1276  }
1277 }
1278 
1279 void ItaniumRecordLayoutBuilder::Layout(const RecordDecl *D) {
1280  InitializeLayout(D);
1281  LayoutFields(D);
1282 
1283  // Finally, round the size of the total struct up to the alignment of the
1284  // struct itself.
1285  FinishLayout(D);
1286 }
1287 
1288 void ItaniumRecordLayoutBuilder::Layout(const CXXRecordDecl *RD) {
1289  InitializeLayout(RD);
1290 
1291  // Lay out the vtable and the non-virtual bases.
1292  LayoutNonVirtualBases(RD);
1293 
1294  LayoutFields(RD);
1295 
1296  NonVirtualSize = Context.toCharUnitsFromBits(
1297  llvm::alignTo(getSizeInBits(), Context.getTargetInfo().getCharAlign()));
1298  NonVirtualAlignment = Alignment;
1299 
1300  // Lay out the virtual bases and add the primary virtual base offsets.
1301  LayoutVirtualBases(RD, RD);
1302 
1303  // Finally, round the size of the total struct up to the alignment
1304  // of the struct itself.
1305  FinishLayout(RD);
1306 
1307 #ifndef NDEBUG
1308  // Check that we have base offsets for all bases.
1309  for (const CXXBaseSpecifier &Base : RD->bases()) {
1310  if (Base.isVirtual())
1311  continue;
1312 
1313  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1314 
1315  assert(Bases.count(BaseDecl) && "Did not find base offset!");
1316  }
1317 
1318  // And all virtual bases.
1319  for (const CXXBaseSpecifier &Base : RD->vbases()) {
1320  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1321 
1322  assert(VBases.count(BaseDecl) && "Did not find base offset!");
1323  }
1324 #endif
1325 }
1326 
1327 void ItaniumRecordLayoutBuilder::Layout(const ObjCInterfaceDecl *D) {
1328  if (ObjCInterfaceDecl *SD = D->getSuperClass()) {
1329  const ASTRecordLayout &SL = Context.getASTObjCInterfaceLayout(SD);
1330 
1331  UpdateAlignment(SL.getAlignment());
1332 
1333  // We start laying out ivars not at the end of the superclass
1334  // structure, but at the next byte following the last field.
1335  setSize(SL.getDataSize());
1336  setDataSize(getSize());
1337  }
1338 
1339  InitializeLayout(D);
1340  // Layout each ivar sequentially.
1341  for (const ObjCIvarDecl *IVD = D->all_declared_ivar_begin(); IVD;
1342  IVD = IVD->getNextIvar())
1343  LayoutField(IVD, false);
1344 
1345  // Finally, round the size of the total struct up to the alignment of the
1346  // struct itself.
1347  FinishLayout(D);
1348 }
1349 
1350 void ItaniumRecordLayoutBuilder::LayoutFields(const RecordDecl *D) {
1351  // Layout each field, for now, just sequentially, respecting alignment. In
1352  // the future, this will need to be tweakable by targets.
1353  bool InsertExtraPadding = D->mayInsertExtraPadding(/*EmitRemark=*/true);
1354  bool HasFlexibleArrayMember = D->hasFlexibleArrayMember();
1355  for (auto I = D->field_begin(), End = D->field_end(); I != End; ++I) {
1356  auto Next(I);
1357  ++Next;
1358  LayoutField(*I,
1359  InsertExtraPadding && (Next != End || !HasFlexibleArrayMember));
1360  }
1361 }
1362 
1363 // Rounds the specified size to have it a multiple of the char size.
1364 static uint64_t
1366  const ASTContext &Context) {
1367  uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
1368  return llvm::alignTo(Size, CharAlignment);
1369 }
1370 
1371 void ItaniumRecordLayoutBuilder::LayoutWideBitField(uint64_t FieldSize,
1372  uint64_t TypeSize,
1373  bool FieldPacked,
1374  const FieldDecl *D) {
1375  assert(Context.getLangOpts().CPlusPlus &&
1376  "Can only have wide bit-fields in C++!");
1377 
1378  // Itanium C++ ABI 2.4:
1379  // If sizeof(T)*8 < n, let T' be the largest integral POD type with
1380  // sizeof(T')*8 <= n.
1381 
1382  QualType IntegralPODTypes[] = {
1383  Context.UnsignedCharTy, Context.UnsignedShortTy, Context.UnsignedIntTy,
1384  Context.UnsignedLongTy, Context.UnsignedLongLongTy
1385  };
1386 
1387  QualType Type;
1388  for (const QualType &QT : IntegralPODTypes) {
1389  uint64_t Size = Context.getTypeSize(QT);
1390 
1391  if (Size > FieldSize)
1392  break;
1393 
1394  Type = QT;
1395  }
1396  assert(!Type.isNull() && "Did not find a type!");
1397 
1398  CharUnits TypeAlign = Context.getTypeAlignInChars(Type);
1399 
1400  // We're not going to use any of the unfilled bits in the last byte.
1401  UnfilledBitsInLastUnit = 0;
1402  LastBitfieldTypeSize = 0;
1403 
1404  uint64_t FieldOffset;
1405  uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
1406 
1407  if (IsUnion) {
1408  uint64_t RoundedFieldSize = roundUpSizeToCharAlignment(FieldSize,
1409  Context);
1410  setDataSize(std::max(getDataSizeInBits(), RoundedFieldSize));
1411  FieldOffset = 0;
1412  } else {
1413  // The bitfield is allocated starting at the next offset aligned
1414  // appropriately for T', with length n bits.
1415  FieldOffset = llvm::alignTo(getDataSizeInBits(), Context.toBits(TypeAlign));
1416 
1417  uint64_t NewSizeInBits = FieldOffset + FieldSize;
1418 
1419  setDataSize(
1420  llvm::alignTo(NewSizeInBits, Context.getTargetInfo().getCharAlign()));
1421  UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;
1422  }
1423 
1424  // Place this field at the current location.
1425  FieldOffsets.push_back(FieldOffset);
1426 
1427  CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, FieldOffset,
1428  Context.toBits(TypeAlign), FieldPacked, D);
1429 
1430  // Update the size.
1431  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1432 
1433  // Remember max struct/class alignment.
1434  UpdateAlignment(TypeAlign);
1435 }
1436 
1437 void ItaniumRecordLayoutBuilder::LayoutBitField(const FieldDecl *D) {
1438  bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
1439  uint64_t FieldSize = D->getBitWidthValue(Context);
1440  TypeInfo FieldInfo = Context.getTypeInfo(D->getType());
1441  uint64_t TypeSize = FieldInfo.Width;
1442  unsigned FieldAlign = FieldInfo.Align;
1443 
1444  // UnfilledBitsInLastUnit is the difference between the end of the
1445  // last allocated bitfield (i.e. the first bit offset available for
1446  // bitfields) and the end of the current data size in bits (i.e. the
1447  // first bit offset available for non-bitfields). The current data
1448  // size in bits is always a multiple of the char size; additionally,
1449  // for ms_struct records it's also a multiple of the
1450  // LastBitfieldTypeSize (if set).
1451 
1452  // The struct-layout algorithm is dictated by the platform ABI,
1453  // which in principle could use almost any rules it likes. In
1454  // practice, UNIXy targets tend to inherit the algorithm described
1455  // in the System V generic ABI. The basic bitfield layout rule in
1456  // System V is to place bitfields at the next available bit offset
1457  // where the entire bitfield would fit in an aligned storage unit of
1458  // the declared type; it's okay if an earlier or later non-bitfield
1459  // is allocated in the same storage unit. However, some targets
1460  // (those that !useBitFieldTypeAlignment(), e.g. ARM APCS) don't
1461  // require this storage unit to be aligned, and therefore always put
1462  // the bitfield at the next available bit offset.
1463 
1464  // ms_struct basically requests a complete replacement of the
1465  // platform ABI's struct-layout algorithm, with the high-level goal
1466  // of duplicating MSVC's layout. For non-bitfields, this follows
1467  // the standard algorithm. The basic bitfield layout rule is to
1468  // allocate an entire unit of the bitfield's declared type
1469  // (e.g. 'unsigned long'), then parcel it up among successive
1470  // bitfields whose declared types have the same size, making a new
1471  // unit as soon as the last can no longer store the whole value.
1472  // Since it completely replaces the platform ABI's algorithm,
1473  // settings like !useBitFieldTypeAlignment() do not apply.
1474 
1475  // A zero-width bitfield forces the use of a new storage unit for
1476  // later bitfields. In general, this occurs by rounding up the
1477  // current size of the struct as if the algorithm were about to
1478  // place a non-bitfield of the field's formal type. Usually this
1479  // does not change the alignment of the struct itself, but it does
1480  // on some targets (those that useZeroLengthBitfieldAlignment(),
1481  // e.g. ARM). In ms_struct layout, zero-width bitfields are
1482  // ignored unless they follow a non-zero-width bitfield.
1483 
1484  // A field alignment restriction (e.g. from #pragma pack) or
1485  // specification (e.g. from __attribute__((aligned))) changes the
1486  // formal alignment of the field. For System V, this alters the
1487  // required alignment of the notional storage unit that must contain
1488  // the bitfield. For ms_struct, this only affects the placement of
1489  // new storage units. In both cases, the effect of #pragma pack is
1490  // ignored on zero-width bitfields.
1491 
1492  // On System V, a packed field (e.g. from #pragma pack or
1493  // __attribute__((packed))) always uses the next available bit
1494  // offset.
1495 
1496  // In an ms_struct struct, the alignment of a fundamental type is
1497  // always equal to its size. This is necessary in order to mimic
1498  // the i386 alignment rules on targets which might not fully align
1499  // all types (e.g. Darwin PPC32, where alignof(long long) == 4).
1500 
1501  // First, some simple bookkeeping to perform for ms_struct structs.
1502  if (IsMsStruct) {
1503  // The field alignment for integer types is always the size.
1504  FieldAlign = TypeSize;
1505 
1506  // If the previous field was not a bitfield, or was a bitfield
1507  // with a different storage unit size, we're done with that
1508  // storage unit.
1509  if (LastBitfieldTypeSize != TypeSize) {
1510  // Also, ignore zero-length bitfields after non-bitfields.
1511  if (!LastBitfieldTypeSize && !FieldSize)
1512  FieldAlign = 1;
1513 
1514  UnfilledBitsInLastUnit = 0;
1515  LastBitfieldTypeSize = 0;
1516  }
1517  }
1518 
1519  // If the field is wider than its declared type, it follows
1520  // different rules in all cases.
1521  if (FieldSize > TypeSize) {
1522  LayoutWideBitField(FieldSize, TypeSize, FieldPacked, D);
1523  return;
1524  }
1525 
1526  // Compute the next available bit offset.
1527  uint64_t FieldOffset =
1528  IsUnion ? 0 : (getDataSizeInBits() - UnfilledBitsInLastUnit);
1529 
1530  // Handle targets that don't honor bitfield type alignment.
1531  if (!IsMsStruct && !Context.getTargetInfo().useBitFieldTypeAlignment()) {
1532  // Some such targets do honor it on zero-width bitfields.
1533  if (FieldSize == 0 &&
1535  // The alignment to round up to is the max of the field's natural
1536  // alignment and a target-specific fixed value (sometimes zero).
1537  unsigned ZeroLengthBitfieldBoundary =
1539  FieldAlign = std::max(FieldAlign, ZeroLengthBitfieldBoundary);
1540 
1541  // If that doesn't apply, just ignore the field alignment.
1542  } else {
1543  FieldAlign = 1;
1544  }
1545  }
1546 
1547  // Remember the alignment we would have used if the field were not packed.
1548  unsigned UnpackedFieldAlign = FieldAlign;
1549 
1550  // Ignore the field alignment if the field is packed unless it has zero-size.
1551  if (!IsMsStruct && FieldPacked && FieldSize != 0)
1552  FieldAlign = 1;
1553 
1554  // But, if there's an 'aligned' attribute on the field, honor that.
1555  unsigned ExplicitFieldAlign = D->getMaxAlignment();
1556  if (ExplicitFieldAlign) {
1557  FieldAlign = std::max(FieldAlign, ExplicitFieldAlign);
1558  UnpackedFieldAlign = std::max(UnpackedFieldAlign, ExplicitFieldAlign);
1559  }
1560 
1561  // But, if there's a #pragma pack in play, that takes precedent over
1562  // even the 'aligned' attribute, for non-zero-width bitfields.
1563  unsigned MaxFieldAlignmentInBits = Context.toBits(MaxFieldAlignment);
1564  if (!MaxFieldAlignment.isZero() && FieldSize) {
1565  UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignmentInBits);
1566  if (FieldPacked)
1567  FieldAlign = UnpackedFieldAlign;
1568  else
1569  FieldAlign = std::min(FieldAlign, MaxFieldAlignmentInBits);
1570  }
1571 
1572  // But, ms_struct just ignores all of that in unions, even explicit
1573  // alignment attributes.
1574  if (IsMsStruct && IsUnion) {
1575  FieldAlign = UnpackedFieldAlign = 1;
1576  }
1577 
1578  // For purposes of diagnostics, we're going to simultaneously
1579  // compute the field offsets that we would have used if we weren't
1580  // adding any alignment padding or if the field weren't packed.
1581  uint64_t UnpaddedFieldOffset = FieldOffset;
1582  uint64_t UnpackedFieldOffset = FieldOffset;
1583 
1584  // Check if we need to add padding to fit the bitfield within an
1585  // allocation unit with the right size and alignment. The rules are
1586  // somewhat different here for ms_struct structs.
1587  if (IsMsStruct) {
1588  // If it's not a zero-width bitfield, and we can fit the bitfield
1589  // into the active storage unit (and we haven't already decided to
1590  // start a new storage unit), just do so, regardless of any other
1591  // other consideration. Otherwise, round up to the right alignment.
1592  if (FieldSize == 0 || FieldSize > UnfilledBitsInLastUnit) {
1593  FieldOffset = llvm::alignTo(FieldOffset, FieldAlign);
1594  UnpackedFieldOffset =
1595  llvm::alignTo(UnpackedFieldOffset, UnpackedFieldAlign);
1596  UnfilledBitsInLastUnit = 0;
1597  }
1598 
1599  } else {
1600  // #pragma pack, with any value, suppresses the insertion of padding.
1601  bool AllowPadding = MaxFieldAlignment.isZero();
1602 
1603  // Compute the real offset.
1604  if (FieldSize == 0 ||
1605  (AllowPadding &&
1606  (FieldOffset & (FieldAlign-1)) + FieldSize > TypeSize)) {
1607  FieldOffset = llvm::alignTo(FieldOffset, FieldAlign);
1608  } else if (ExplicitFieldAlign &&
1609  (MaxFieldAlignmentInBits == 0 ||
1610  ExplicitFieldAlign <= MaxFieldAlignmentInBits) &&
1612  // TODO: figure it out what needs to be done on targets that don't honor
1613  // bit-field type alignment like ARM APCS ABI.
1614  FieldOffset = llvm::alignTo(FieldOffset, ExplicitFieldAlign);
1615  }
1616 
1617  // Repeat the computation for diagnostic purposes.
1618  if (FieldSize == 0 ||
1619  (AllowPadding &&
1620  (UnpackedFieldOffset & (UnpackedFieldAlign-1)) + FieldSize > TypeSize))
1621  UnpackedFieldOffset =
1622  llvm::alignTo(UnpackedFieldOffset, UnpackedFieldAlign);
1623  else if (ExplicitFieldAlign &&
1624  (MaxFieldAlignmentInBits == 0 ||
1625  ExplicitFieldAlign <= MaxFieldAlignmentInBits) &&
1627  UnpackedFieldOffset =
1628  llvm::alignTo(UnpackedFieldOffset, ExplicitFieldAlign);
1629  }
1630 
1631  // If we're using external layout, give the external layout a chance
1632  // to override this information.
1633  if (UseExternalLayout)
1634  FieldOffset = updateExternalFieldOffset(D, FieldOffset);
1635 
1636  // Okay, place the bitfield at the calculated offset.
1637  FieldOffsets.push_back(FieldOffset);
1638 
1639  // Bookkeeping:
1640 
1641  // Anonymous members don't affect the overall record alignment,
1642  // except on targets where they do.
1643  if (!IsMsStruct &&
1645  !D->getIdentifier())
1646  FieldAlign = UnpackedFieldAlign = 1;
1647 
1648  // Diagnose differences in layout due to padding or packing.
1649  if (!UseExternalLayout)
1650  CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, UnpackedFieldOffset,
1651  UnpackedFieldAlign, FieldPacked, D);
1652 
1653  // Update DataSize to include the last byte containing (part of) the bitfield.
1654 
1655  // For unions, this is just a max operation, as usual.
1656  if (IsUnion) {
1657  // For ms_struct, allocate the entire storage unit --- unless this
1658  // is a zero-width bitfield, in which case just use a size of 1.
1659  uint64_t RoundedFieldSize;
1660  if (IsMsStruct) {
1661  RoundedFieldSize =
1662  (FieldSize ? TypeSize : Context.getTargetInfo().getCharWidth());
1663 
1664  // Otherwise, allocate just the number of bytes required to store
1665  // the bitfield.
1666  } else {
1667  RoundedFieldSize = roundUpSizeToCharAlignment(FieldSize, Context);
1668  }
1669  setDataSize(std::max(getDataSizeInBits(), RoundedFieldSize));
1670 
1671  // For non-zero-width bitfields in ms_struct structs, allocate a new
1672  // storage unit if necessary.
1673  } else if (IsMsStruct && FieldSize) {
1674  // We should have cleared UnfilledBitsInLastUnit in every case
1675  // where we changed storage units.
1676  if (!UnfilledBitsInLastUnit) {
1677  setDataSize(FieldOffset + TypeSize);
1678  UnfilledBitsInLastUnit = TypeSize;
1679  }
1680  UnfilledBitsInLastUnit -= FieldSize;
1681  LastBitfieldTypeSize = TypeSize;
1682 
1683  // Otherwise, bump the data size up to include the bitfield,
1684  // including padding up to char alignment, and then remember how
1685  // bits we didn't use.
1686  } else {
1687  uint64_t NewSizeInBits = FieldOffset + FieldSize;
1688  uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
1689  setDataSize(llvm::alignTo(NewSizeInBits, CharAlignment));
1690  UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;
1691 
1692  // The only time we can get here for an ms_struct is if this is a
1693  // zero-width bitfield, which doesn't count as anything for the
1694  // purposes of unfilled bits.
1695  LastBitfieldTypeSize = 0;
1696  }
1697 
1698  // Update the size.
1699  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1700 
1701  // Remember max struct/class alignment.
1702  UpdateAlignment(Context.toCharUnitsFromBits(FieldAlign),
1703  Context.toCharUnitsFromBits(UnpackedFieldAlign));
1704 }
1705 
1706 void ItaniumRecordLayoutBuilder::LayoutField(const FieldDecl *D,
1707  bool InsertExtraPadding) {
1708  if (D->isBitField()) {
1709  LayoutBitField(D);
1710  return;
1711  }
1712 
1713  uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
1714 
1715  // Reset the unfilled bits.
1716  UnfilledBitsInLastUnit = 0;
1717  LastBitfieldTypeSize = 0;
1718 
1719  bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
1720  CharUnits FieldOffset =
1721  IsUnion ? CharUnits::Zero() : getDataSize();
1722  CharUnits FieldSize;
1723  CharUnits FieldAlign;
1724 
1725  if (D->getType()->isIncompleteArrayType()) {
1726  // This is a flexible array member; we can't directly
1727  // query getTypeInfo about these, so we figure it out here.
1728  // Flexible array members don't have any size, but they
1729  // have to be aligned appropriately for their element type.
1730  FieldSize = CharUnits::Zero();
1731  const ArrayType* ATy = Context.getAsArrayType(D->getType());
1732  FieldAlign = Context.getTypeAlignInChars(ATy->getElementType());
1733  } else if (const ReferenceType *RT = D->getType()->getAs<ReferenceType>()) {
1734  unsigned AS = Context.getTargetAddressSpace(RT->getPointeeType());
1735  FieldSize =
1736  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(AS));
1737  FieldAlign =
1738  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(AS));
1739  } else {
1740  std::pair<CharUnits, CharUnits> FieldInfo =
1741  Context.getTypeInfoInChars(D->getType());
1742  FieldSize = FieldInfo.first;
1743  FieldAlign = FieldInfo.second;
1744 
1745  if (IsMsStruct) {
1746  // If MS bitfield layout is required, figure out what type is being
1747  // laid out and align the field to the width of that type.
1748 
1749  // Resolve all typedefs down to their base type and round up the field
1750  // alignment if necessary.
1751  QualType T = Context.getBaseElementType(D->getType());
1752  if (const BuiltinType *BTy = T->getAs<BuiltinType>()) {
1753  CharUnits TypeSize = Context.getTypeSizeInChars(BTy);
1754  if (TypeSize > FieldAlign)
1755  FieldAlign = TypeSize;
1756  }
1757  }
1758  }
1759 
1760  // The align if the field is not packed. This is to check if the attribute
1761  // was unnecessary (-Wpacked).
1762  CharUnits UnpackedFieldAlign = FieldAlign;
1763  CharUnits UnpackedFieldOffset = FieldOffset;
1764 
1765  if (FieldPacked)
1766  FieldAlign = CharUnits::One();
1767  CharUnits MaxAlignmentInChars =
1768  Context.toCharUnitsFromBits(D->getMaxAlignment());
1769  FieldAlign = std::max(FieldAlign, MaxAlignmentInChars);
1770  UnpackedFieldAlign = std::max(UnpackedFieldAlign, MaxAlignmentInChars);
1771 
1772  // The maximum field alignment overrides the aligned attribute.
1773  if (!MaxFieldAlignment.isZero()) {
1774  FieldAlign = std::min(FieldAlign, MaxFieldAlignment);
1775  UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignment);
1776  }
1777 
1778  // Round up the current record size to the field's alignment boundary.
1779  FieldOffset = FieldOffset.alignTo(FieldAlign);
1780  UnpackedFieldOffset = UnpackedFieldOffset.alignTo(UnpackedFieldAlign);
1781 
1782  if (UseExternalLayout) {
1783  FieldOffset = Context.toCharUnitsFromBits(
1784  updateExternalFieldOffset(D, Context.toBits(FieldOffset)));
1785 
1786  if (!IsUnion && EmptySubobjects) {
1787  // Record the fact that we're placing a field at this offset.
1788  bool Allowed = EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset);
1789  (void)Allowed;
1790  assert(Allowed && "Externally-placed field cannot be placed here");
1791  }
1792  } else {
1793  if (!IsUnion && EmptySubobjects) {
1794  // Check if we can place the field at this offset.
1795  while (!EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset)) {
1796  // We couldn't place the field at the offset. Try again at a new offset.
1797  FieldOffset += FieldAlign;
1798  }
1799  }
1800  }
1801 
1802  // Place this field at the current location.
1803  FieldOffsets.push_back(Context.toBits(FieldOffset));
1804 
1805  if (!UseExternalLayout)
1806  CheckFieldPadding(Context.toBits(FieldOffset), UnpaddedFieldOffset,
1807  Context.toBits(UnpackedFieldOffset),
1808  Context.toBits(UnpackedFieldAlign), FieldPacked, D);
1809 
1810  if (InsertExtraPadding) {
1811  CharUnits ASanAlignment = CharUnits::fromQuantity(8);
1812  CharUnits ExtraSizeForAsan = ASanAlignment;
1813  if (FieldSize % ASanAlignment)
1814  ExtraSizeForAsan +=
1815  ASanAlignment - CharUnits::fromQuantity(FieldSize % ASanAlignment);
1816  FieldSize += ExtraSizeForAsan;
1817  }
1818 
1819  // Reserve space for this field.
1820  uint64_t FieldSizeInBits = Context.toBits(FieldSize);
1821  if (IsUnion)
1822  setDataSize(std::max(getDataSizeInBits(), FieldSizeInBits));
1823  else
1824  setDataSize(FieldOffset + FieldSize);
1825 
1826  // Update the size.
1827  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1828 
1829  // Remember max struct/class alignment.
1830  UpdateAlignment(FieldAlign, UnpackedFieldAlign);
1831 }
1832 
1833 void ItaniumRecordLayoutBuilder::FinishLayout(const NamedDecl *D) {
1834  // In C++, records cannot be of size 0.
1835  if (Context.getLangOpts().CPlusPlus && getSizeInBits() == 0) {
1836  if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) {
1837  // Compatibility with gcc requires a class (pod or non-pod)
1838  // which is not empty but of size 0; such as having fields of
1839  // array of zero-length, remains of Size 0
1840  if (RD->isEmpty())
1841  setSize(CharUnits::One());
1842  }
1843  else
1844  setSize(CharUnits::One());
1845  }
1846 
1847  // Finally, round the size of the record up to the alignment of the
1848  // record itself.
1849  uint64_t UnpaddedSize = getSizeInBits() - UnfilledBitsInLastUnit;
1850  uint64_t UnpackedSizeInBits =
1851  llvm::alignTo(getSizeInBits(), Context.toBits(UnpackedAlignment));
1852  uint64_t RoundedSize =
1853  llvm::alignTo(getSizeInBits(), Context.toBits(Alignment));
1854 
1855  if (UseExternalLayout) {
1856  // If we're inferring alignment, and the external size is smaller than
1857  // our size after we've rounded up to alignment, conservatively set the
1858  // alignment to 1.
1859  if (InferAlignment && External.Size < RoundedSize) {
1860  Alignment = CharUnits::One();
1861  InferAlignment = false;
1862  }
1863  setSize(External.Size);
1864  return;
1865  }
1866 
1867  // Set the size to the final size.
1868  setSize(RoundedSize);
1869 
1870  unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
1871  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
1872  // Warn if padding was introduced to the struct/class/union.
1873  if (getSizeInBits() > UnpaddedSize) {
1874  unsigned PadSize = getSizeInBits() - UnpaddedSize;
1875  bool InBits = true;
1876  if (PadSize % CharBitNum == 0) {
1877  PadSize = PadSize / CharBitNum;
1878  InBits = false;
1879  }
1880  Diag(RD->getLocation(), diag::warn_padded_struct_size)
1881  << Context.getTypeDeclType(RD)
1882  << PadSize
1883  << (InBits ? 1 : 0); // (byte|bit)
1884  }
1885 
1886  // Warn if we packed it unnecessarily, when the unpacked alignment is not
1887  // greater than the one after packing, the size in bits doesn't change and
1888  // the offset of each field is identical.
1889  if (Packed && UnpackedAlignment <= Alignment &&
1890  UnpackedSizeInBits == getSizeInBits() && !HasPackedField)
1891  Diag(D->getLocation(), diag::warn_unnecessary_packed)
1892  << Context.getTypeDeclType(RD);
1893  }
1894 }
1895 
1896 void ItaniumRecordLayoutBuilder::UpdateAlignment(
1897  CharUnits NewAlignment, CharUnits UnpackedNewAlignment) {
1898  // The alignment is not modified when using 'mac68k' alignment or when
1899  // we have an externally-supplied layout that also provides overall alignment.
1900  if (IsMac68kAlign || (UseExternalLayout && !InferAlignment))
1901  return;
1902 
1903  if (NewAlignment > Alignment) {
1904  assert(llvm::isPowerOf2_64(NewAlignment.getQuantity()) &&
1905  "Alignment not a power of 2");
1906  Alignment = NewAlignment;
1907  }
1908 
1909  if (UnpackedNewAlignment > UnpackedAlignment) {
1910  assert(llvm::isPowerOf2_64(UnpackedNewAlignment.getQuantity()) &&
1911  "Alignment not a power of 2");
1912  UnpackedAlignment = UnpackedNewAlignment;
1913  }
1914 }
1915 
1916 uint64_t
1917 ItaniumRecordLayoutBuilder::updateExternalFieldOffset(const FieldDecl *Field,
1918  uint64_t ComputedOffset) {
1919  uint64_t ExternalFieldOffset = External.getExternalFieldOffset(Field);
1920 
1921  if (InferAlignment && ExternalFieldOffset < ComputedOffset) {
1922  // The externally-supplied field offset is before the field offset we
1923  // computed. Assume that the structure is packed.
1924  Alignment = CharUnits::One();
1925  InferAlignment = false;
1926  }
1927 
1928  // Use the externally-supplied field offset.
1929  return ExternalFieldOffset;
1930 }
1931 
1932 /// \brief Get diagnostic %select index for tag kind for
1933 /// field padding diagnostic message.
1934 /// WARNING: Indexes apply to particular diagnostics only!
1935 ///
1936 /// \returns diagnostic %select index.
1938  switch (Tag) {
1939  case TTK_Struct: return 0;
1940  case TTK_Interface: return 1;
1941  case TTK_Class: return 2;
1942  default: llvm_unreachable("Invalid tag kind for field padding diagnostic!");
1943  }
1944 }
1945 
1946 void ItaniumRecordLayoutBuilder::CheckFieldPadding(
1947  uint64_t Offset, uint64_t UnpaddedOffset, uint64_t UnpackedOffset,
1948  unsigned UnpackedAlign, bool isPacked, const FieldDecl *D) {
1949  // We let objc ivars without warning, objc interfaces generally are not used
1950  // for padding tricks.
1951  if (isa<ObjCIvarDecl>(D))
1952  return;
1953 
1954  // Don't warn about structs created without a SourceLocation. This can
1955  // be done by clients of the AST, such as codegen.
1956  if (D->getLocation().isInvalid())
1957  return;
1958 
1959  unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
1960 
1961  // Warn if padding was introduced to the struct/class.
1962  if (!IsUnion && Offset > UnpaddedOffset) {
1963  unsigned PadSize = Offset - UnpaddedOffset;
1964  bool InBits = true;
1965  if (PadSize % CharBitNum == 0) {
1966  PadSize = PadSize / CharBitNum;
1967  InBits = false;
1968  }
1969  if (D->getIdentifier())
1970  Diag(D->getLocation(), diag::warn_padded_struct_field)
1972  << Context.getTypeDeclType(D->getParent())
1973  << PadSize
1974  << (InBits ? 1 : 0) // (byte|bit)
1975  << D->getIdentifier();
1976  else
1977  Diag(D->getLocation(), diag::warn_padded_struct_anon_field)
1979  << Context.getTypeDeclType(D->getParent())
1980  << PadSize
1981  << (InBits ? 1 : 0); // (byte|bit)
1982  }
1983  if (isPacked && Offset != UnpackedOffset) {
1984  HasPackedField = true;
1985  }
1986 }
1987 
1989  const CXXRecordDecl *RD) {
1990  // If a class isn't polymorphic it doesn't have a key function.
1991  if (!RD->isPolymorphic())
1992  return nullptr;
1993 
1994  // A class that is not externally visible doesn't have a key function. (Or
1995  // at least, there's no point to assigning a key function to such a class;
1996  // this doesn't affect the ABI.)
1997  if (!RD->isExternallyVisible())
1998  return nullptr;
1999 
2000  // Template instantiations don't have key functions per Itanium C++ ABI 5.2.6.
2001  // Same behavior as GCC.
2003  if (TSK == TSK_ImplicitInstantiation ||
2006  return nullptr;
2007 
2008  bool allowInlineFunctions =
2010 
2011  for (const CXXMethodDecl *MD : RD->methods()) {
2012  if (!MD->isVirtual())
2013  continue;
2014 
2015  if (MD->isPure())
2016  continue;
2017 
2018  // Ignore implicit member functions, they are always marked as inline, but
2019  // they don't have a body until they're defined.
2020  if (MD->isImplicit())
2021  continue;
2022 
2023  if (MD->isInlineSpecified())
2024  continue;
2025 
2026  if (MD->hasInlineBody())
2027  continue;
2028 
2029  // Ignore inline deleted or defaulted functions.
2030  if (!MD->isUserProvided())
2031  continue;
2032 
2033  // In certain ABIs, ignore functions with out-of-line inline definitions.
2034  if (!allowInlineFunctions) {
2035  const FunctionDecl *Def;
2036  if (MD->hasBody(Def) && Def->isInlineSpecified())
2037  continue;
2038  }
2039 
2040  if (Context.getLangOpts().CUDA) {
2041  // While compiler may see key method in this TU, during CUDA
2042  // compilation we should ignore methods that are not accessible
2043  // on this side of compilation.
2044  if (Context.getLangOpts().CUDAIsDevice) {
2045  // In device mode ignore methods without __device__ attribute.
2046  if (!MD->hasAttr<CUDADeviceAttr>())
2047  continue;
2048  } else {
2049  // In host mode ignore __device__-only methods.
2050  if (!MD->hasAttr<CUDAHostAttr>() && MD->hasAttr<CUDADeviceAttr>())
2051  continue;
2052  }
2053  }
2054 
2055  // If the key function is dllimport but the class isn't, then the class has
2056  // no key function. The DLL that exports the key function won't export the
2057  // vtable in this case.
2058  if (MD->hasAttr<DLLImportAttr>() && !RD->hasAttr<DLLImportAttr>())
2059  return nullptr;
2060 
2061  // We found it.
2062  return MD;
2063  }
2064 
2065  return nullptr;
2066 }
2067 
2069  unsigned DiagID) {
2070  return Context.getDiagnostics().Report(Loc, DiagID);
2071 }
2072 
2073 /// Does the target C++ ABI require us to skip over the tail-padding
2074 /// of the given class (considering it as a base class) when allocating
2075 /// objects?
2076 static bool mustSkipTailPadding(TargetCXXABI ABI, const CXXRecordDecl *RD) {
2077  switch (ABI.getTailPaddingUseRules()) {
2079  return false;
2080 
2082  // FIXME: To the extent that this is meant to cover the Itanium ABI
2083  // rules, we should implement the restrictions about over-sized
2084  // bitfields:
2085  //
2086  // http://itanium-cxx-abi.github.io/cxx-abi/abi.html#POD :
2087  // In general, a type is considered a POD for the purposes of
2088  // layout if it is a POD type (in the sense of ISO C++
2089  // [basic.types]). However, a POD-struct or POD-union (in the
2090  // sense of ISO C++ [class]) with a bitfield member whose
2091  // declared width is wider than the declared type of the
2092  // bitfield is not a POD for the purpose of layout. Similarly,
2093  // an array type is not a POD for the purpose of layout if the
2094  // element type of the array is not a POD for the purpose of
2095  // layout.
2096  //
2097  // Where references to the ISO C++ are made in this paragraph,
2098  // the Technical Corrigendum 1 version of the standard is
2099  // intended.
2100  return RD->isPOD();
2101 
2103  // This is equivalent to RD->getTypeForDecl().isCXX11PODType(),
2104  // but with a lot of abstraction penalty stripped off. This does
2105  // assume that these properties are set correctly even in C++98
2106  // mode; fortunately, that is true because we want to assign
2107  // consistently semantics to the type-traits intrinsics (or at
2108  // least as many of them as possible).
2109  return RD->isTrivial() && RD->isStandardLayout();
2110  }
2111 
2112  llvm_unreachable("bad tail-padding use kind");
2113 }
2114 
2115 static bool isMsLayout(const ASTContext &Context) {
2116  return Context.getTargetInfo().getCXXABI().isMicrosoft();
2117 }
2118 
2119 // This section contains an implementation of struct layout that is, up to the
2120 // included tests, compatible with cl.exe (2013). The layout produced is
2121 // significantly different than those produced by the Itanium ABI. Here we note
2122 // the most important differences.
2123 //
2124 // * The alignment of bitfields in unions is ignored when computing the
2125 // alignment of the union.
2126 // * The existence of zero-width bitfield that occurs after anything other than
2127 // a non-zero length bitfield is ignored.
2128 // * There is no explicit primary base for the purposes of layout. All bases
2129 // with vfptrs are laid out first, followed by all bases without vfptrs.
2130 // * The Itanium equivalent vtable pointers are split into a vfptr (virtual
2131 // function pointer) and a vbptr (virtual base pointer). They can each be
2132 // shared with a, non-virtual bases. These bases need not be the same. vfptrs
2133 // always occur at offset 0. vbptrs can occur at an arbitrary offset and are
2134 // placed after the lexicographically last non-virtual base. This placement
2135 // is always before fields but can be in the middle of the non-virtual bases
2136 // due to the two-pass layout scheme for non-virtual-bases.
2137 // * Virtual bases sometimes require a 'vtordisp' field that is laid out before
2138 // the virtual base and is used in conjunction with virtual overrides during
2139 // construction and destruction. This is always a 4 byte value and is used as
2140 // an alternative to constructor vtables.
2141 // * vtordisps are allocated in a block of memory with size and alignment equal
2142 // to the alignment of the completed structure (before applying __declspec(
2143 // align())). The vtordisp always occur at the end of the allocation block,
2144 // immediately prior to the virtual base.
2145 // * vfptrs are injected after all bases and fields have been laid out. In
2146 // order to guarantee proper alignment of all fields, the vfptr injection
2147 // pushes all bases and fields back by the alignment imposed by those bases
2148 // and fields. This can potentially add a significant amount of padding.
2149 // vfptrs are always injected at offset 0.
2150 // * vbptrs are injected after all bases and fields have been laid out. In
2151 // order to guarantee proper alignment of all fields, the vfptr injection
2152 // pushes all bases and fields back by the alignment imposed by those bases
2153 // and fields. This can potentially add a significant amount of padding.
2154 // vbptrs are injected immediately after the last non-virtual base as
2155 // lexicographically ordered in the code. If this site isn't pointer aligned
2156 // the vbptr is placed at the next properly aligned location. Enough padding
2157 // is added to guarantee a fit.
2158 // * The last zero sized non-virtual base can be placed at the end of the
2159 // struct (potentially aliasing another object), or may alias with the first
2160 // field, even if they are of the same type.
2161 // * The last zero size virtual base may be placed at the end of the struct
2162 // potentially aliasing another object.
2163 // * The ABI attempts to avoid aliasing of zero sized bases by adding padding
2164 // between bases or vbases with specific properties. The criteria for
2165 // additional padding between two bases is that the first base is zero sized
2166 // or ends with a zero sized subobject and the second base is zero sized or
2167 // trails with a zero sized base or field (sharing of vfptrs can reorder the
2168 // layout of the so the leading base is not always the first one declared).
2169 // This rule does take into account fields that are not records, so padding
2170 // will occur even if the last field is, e.g. an int. The padding added for
2171 // bases is 1 byte. The padding added between vbases depends on the alignment
2172 // of the object but is at least 4 bytes (in both 32 and 64 bit modes).
2173 // * There is no concept of non-virtual alignment, non-virtual alignment and
2174 // alignment are always identical.
2175 // * There is a distinction between alignment and required alignment.
2176 // __declspec(align) changes the required alignment of a struct. This
2177 // alignment is _always_ obeyed, even in the presence of #pragma pack. A
2178 // record inherits required alignment from all of its fields and bases.
2179 // * __declspec(align) on bitfields has the effect of changing the bitfield's
2180 // alignment instead of its required alignment. This is the only known way
2181 // to make the alignment of a struct bigger than 8. Interestingly enough
2182 // this alignment is also immune to the effects of #pragma pack and can be
2183 // used to create structures with large alignment under #pragma pack.
2184 // However, because it does not impact required alignment, such a structure,
2185 // when used as a field or base, will not be aligned if #pragma pack is
2186 // still active at the time of use.
2187 //
2188 // Known incompatibilities:
2189 // * all: #pragma pack between fields in a record
2190 // * 2010 and back: If the last field in a record is a bitfield, every object
2191 // laid out after the record will have extra padding inserted before it. The
2192 // extra padding will have size equal to the size of the storage class of the
2193 // bitfield. 0 sized bitfields don't exhibit this behavior and the extra
2194 // padding can be avoided by adding a 0 sized bitfield after the non-zero-
2195 // sized bitfield.
2196 // * 2012 and back: In 64-bit mode, if the alignment of a record is 16 or
2197 // greater due to __declspec(align()) then a second layout phase occurs after
2198 // The locations of the vf and vb pointers are known. This layout phase
2199 // suffers from the "last field is a bitfield" bug in 2010 and results in
2200 // _every_ field getting padding put in front of it, potentially including the
2201 // vfptr, leaving the vfprt at a non-zero location which results in a fault if
2202 // anything tries to read the vftbl. The second layout phase also treats
2203 // bitfields as separate entities and gives them each storage rather than
2204 // packing them. Additionally, because this phase appears to perform a
2205 // (an unstable) sort on the members before laying them out and because merged
2206 // bitfields have the same address, the bitfields end up in whatever order
2207 // the sort left them in, a behavior we could never hope to replicate.
2208 
2209 namespace {
2210 struct MicrosoftRecordLayoutBuilder {
2211  struct ElementInfo {
2212  CharUnits Size;
2213  CharUnits Alignment;
2214  };
2215  typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
2216  MicrosoftRecordLayoutBuilder(const ASTContext &Context) : Context(Context) {}
2217 private:
2218  MicrosoftRecordLayoutBuilder(const MicrosoftRecordLayoutBuilder &) = delete;
2219  void operator=(const MicrosoftRecordLayoutBuilder &) = delete;
2220 public:
2221  void layout(const RecordDecl *RD);
2222  void cxxLayout(const CXXRecordDecl *RD);
2223  /// \brief Initializes size and alignment and honors some flags.
2224  void initializeLayout(const RecordDecl *RD);
2225  /// \brief Initialized C++ layout, compute alignment and virtual alignment and
2226  /// existence of vfptrs and vbptrs. Alignment is needed before the vfptr is
2227  /// laid out.
2228  void initializeCXXLayout(const CXXRecordDecl *RD);
2229  void layoutNonVirtualBases(const CXXRecordDecl *RD);
2230  void layoutNonVirtualBase(const CXXRecordDecl *RD,
2231  const CXXRecordDecl *BaseDecl,
2232  const ASTRecordLayout &BaseLayout,
2233  const ASTRecordLayout *&PreviousBaseLayout);
2234  void injectVFPtr(const CXXRecordDecl *RD);
2235  void injectVBPtr(const CXXRecordDecl *RD);
2236  /// \brief Lays out the fields of the record. Also rounds size up to
2237  /// alignment.
2238  void layoutFields(const RecordDecl *RD);
2239  void layoutField(const FieldDecl *FD);
2240  void layoutBitField(const FieldDecl *FD);
2241  /// \brief Lays out a single zero-width bit-field in the record and handles
2242  /// special cases associated with zero-width bit-fields.
2243  void layoutZeroWidthBitField(const FieldDecl *FD);
2244  void layoutVirtualBases(const CXXRecordDecl *RD);
2245  void finalizeLayout(const RecordDecl *RD);
2246  /// \brief Gets the size and alignment of a base taking pragma pack and
2247  /// __declspec(align) into account.
2248  ElementInfo getAdjustedElementInfo(const ASTRecordLayout &Layout);
2249  /// \brief Gets the size and alignment of a field taking pragma pack and
2250  /// __declspec(align) into account. It also updates RequiredAlignment as a
2251  /// side effect because it is most convenient to do so here.
2252  ElementInfo getAdjustedElementInfo(const FieldDecl *FD);
2253  /// \brief Places a field at an offset in CharUnits.
2254  void placeFieldAtOffset(CharUnits FieldOffset) {
2255  FieldOffsets.push_back(Context.toBits(FieldOffset));
2256  }
2257  /// \brief Places a bitfield at a bit offset.
2258  void placeFieldAtBitOffset(uint64_t FieldOffset) {
2259  FieldOffsets.push_back(FieldOffset);
2260  }
2261  /// \brief Compute the set of virtual bases for which vtordisps are required.
2262  void computeVtorDispSet(
2263  llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtorDispSet,
2264  const CXXRecordDecl *RD) const;
2265  const ASTContext &Context;
2266  /// \brief The size of the record being laid out.
2267  CharUnits Size;
2268  /// \brief The non-virtual size of the record layout.
2269  CharUnits NonVirtualSize;
2270  /// \brief The data size of the record layout.
2271  CharUnits DataSize;
2272  /// \brief The current alignment of the record layout.
2273  CharUnits Alignment;
2274  /// \brief The maximum allowed field alignment. This is set by #pragma pack.
2275  CharUnits MaxFieldAlignment;
2276  /// \brief The alignment that this record must obey. This is imposed by
2277  /// __declspec(align()) on the record itself or one of its fields or bases.
2278  CharUnits RequiredAlignment;
2279  /// \brief The size of the allocation of the currently active bitfield.
2280  /// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield
2281  /// is true.
2282  CharUnits CurrentBitfieldSize;
2283  /// \brief Offset to the virtual base table pointer (if one exists).
2284  CharUnits VBPtrOffset;
2285  /// \brief Minimum record size possible.
2286  CharUnits MinEmptyStructSize;
2287  /// \brief The size and alignment info of a pointer.
2288  ElementInfo PointerInfo;
2289  /// \brief The primary base class (if one exists).
2290  const CXXRecordDecl *PrimaryBase;
2291  /// \brief The class we share our vb-pointer with.
2292  const CXXRecordDecl *SharedVBPtrBase;
2293  /// \brief The collection of field offsets.
2294  SmallVector<uint64_t, 16> FieldOffsets;
2295  /// \brief Base classes and their offsets in the record.
2296  BaseOffsetsMapTy Bases;
2297  /// \brief virtual base classes and their offsets in the record.
2299  /// \brief The number of remaining bits in our last bitfield allocation.
2300  /// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield is
2301  /// true.
2302  unsigned RemainingBitsInField;
2303  bool IsUnion : 1;
2304  /// \brief True if the last field laid out was a bitfield and was not 0
2305  /// width.
2306  bool LastFieldIsNonZeroWidthBitfield : 1;
2307  /// \brief True if the class has its own vftable pointer.
2308  bool HasOwnVFPtr : 1;
2309  /// \brief True if the class has a vbtable pointer.
2310  bool HasVBPtr : 1;
2311  /// \brief True if the last sub-object within the type is zero sized or the
2312  /// object itself is zero sized. This *does not* count members that are not
2313  /// records. Only used for MS-ABI.
2314  bool EndsWithZeroSizedObject : 1;
2315  /// \brief True if this class is zero sized or first base is zero sized or
2316  /// has this property. Only used for MS-ABI.
2317  bool LeadsWithZeroSizedBase : 1;
2318 
2319  /// \brief True if the external AST source provided a layout for this record.
2320  bool UseExternalLayout : 1;
2321 
2322  /// \brief The layout provided by the external AST source. Only active if
2323  /// UseExternalLayout is true.
2324  ExternalLayout External;
2325 };
2326 } // namespace
2327 
2328 MicrosoftRecordLayoutBuilder::ElementInfo
2329 MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
2330  const ASTRecordLayout &Layout) {
2331  ElementInfo Info;
2332  Info.Alignment = Layout.getAlignment();
2333  // Respect pragma pack.
2334  if (!MaxFieldAlignment.isZero())
2335  Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
2336  // Track zero-sized subobjects here where it's already available.
2337  EndsWithZeroSizedObject = Layout.endsWithZeroSizedObject();
2338  // Respect required alignment, this is necessary because we may have adjusted
2339  // the alignment in the case of pragam pack. Note that the required alignment
2340  // doesn't actually apply to the struct alignment at this point.
2341  Alignment = std::max(Alignment, Info.Alignment);
2342  RequiredAlignment = std::max(RequiredAlignment, Layout.getRequiredAlignment());
2343  Info.Alignment = std::max(Info.Alignment, Layout.getRequiredAlignment());
2344  Info.Size = Layout.getNonVirtualSize();
2345  return Info;
2346 }
2347 
2348 MicrosoftRecordLayoutBuilder::ElementInfo
2349 MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
2350  const FieldDecl *FD) {
2351  // Get the alignment of the field type's natural alignment, ignore any
2352  // alignment attributes.
2353  ElementInfo Info;
2354  std::tie(Info.Size, Info.Alignment) =
2356  // Respect align attributes on the field.
2357  CharUnits FieldRequiredAlignment =
2358  Context.toCharUnitsFromBits(FD->getMaxAlignment());
2359  // Respect align attributes on the type.
2360  if (Context.isAlignmentRequired(FD->getType()))
2361  FieldRequiredAlignment = std::max(
2362  Context.getTypeAlignInChars(FD->getType()), FieldRequiredAlignment);
2363  // Respect attributes applied to subobjects of the field.
2364  if (FD->isBitField())
2365  // For some reason __declspec align impacts alignment rather than required
2366  // alignment when it is applied to bitfields.
2367  Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
2368  else {
2369  if (auto RT =
2371  auto const &Layout = Context.getASTRecordLayout(RT->getDecl());
2372  EndsWithZeroSizedObject = Layout.endsWithZeroSizedObject();
2373  FieldRequiredAlignment = std::max(FieldRequiredAlignment,
2374  Layout.getRequiredAlignment());
2375  }
2376  // Capture required alignment as a side-effect.
2377  RequiredAlignment = std::max(RequiredAlignment, FieldRequiredAlignment);
2378  }
2379  // Respect pragma pack, attribute pack and declspec align
2380  if (!MaxFieldAlignment.isZero())
2381  Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
2382  if (FD->hasAttr<PackedAttr>())
2383  Info.Alignment = CharUnits::One();
2384  Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
2385  return Info;
2386 }
2387 
2388 void MicrosoftRecordLayoutBuilder::layout(const RecordDecl *RD) {
2389  // For C record layout, zero-sized records always have size 4.
2390  MinEmptyStructSize = CharUnits::fromQuantity(4);
2391  initializeLayout(RD);
2392  layoutFields(RD);
2393  DataSize = Size = Size.alignTo(Alignment);
2394  RequiredAlignment = std::max(
2395  RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
2396  finalizeLayout(RD);
2397 }
2398 
2399 void MicrosoftRecordLayoutBuilder::cxxLayout(const CXXRecordDecl *RD) {
2400  // The C++ standard says that empty structs have size 1.
2401  MinEmptyStructSize = CharUnits::One();
2402  initializeLayout(RD);
2403  initializeCXXLayout(RD);
2404  layoutNonVirtualBases(RD);
2405  layoutFields(RD);
2406  injectVBPtr(RD);
2407  injectVFPtr(RD);
2408  if (HasOwnVFPtr || (HasVBPtr && !SharedVBPtrBase))
2409  Alignment = std::max(Alignment, PointerInfo.Alignment);
2410  auto RoundingAlignment = Alignment;
2411  if (!MaxFieldAlignment.isZero())
2412  RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
2413  NonVirtualSize = Size = Size.alignTo(RoundingAlignment);
2414  RequiredAlignment = std::max(
2415  RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
2416  layoutVirtualBases(RD);
2417  finalizeLayout(RD);
2418 }
2419 
2420 void MicrosoftRecordLayoutBuilder::initializeLayout(const RecordDecl *RD) {
2421  IsUnion = RD->isUnion();
2422  Size = CharUnits::Zero();
2423  Alignment = CharUnits::One();
2424  // In 64-bit mode we always perform an alignment step after laying out vbases.
2425  // In 32-bit mode we do not. The check to see if we need to perform alignment
2426  // checks the RequiredAlignment field and performs alignment if it isn't 0.
2427  RequiredAlignment = Context.getTargetInfo().getTriple().isArch64Bit()
2428  ? CharUnits::One()
2429  : CharUnits::Zero();
2430  // Compute the maximum field alignment.
2431  MaxFieldAlignment = CharUnits::Zero();
2432  // Honor the default struct packing maximum alignment flag.
2433  if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct)
2434  MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
2435  // Honor the packing attribute. The MS-ABI ignores pragma pack if its larger
2436  // than the pointer size.
2437  if (const MaxFieldAlignmentAttr *MFAA = RD->getAttr<MaxFieldAlignmentAttr>()){
2438  unsigned PackedAlignment = MFAA->getAlignment();
2439  if (PackedAlignment <= Context.getTargetInfo().getPointerWidth(0))
2440  MaxFieldAlignment = Context.toCharUnitsFromBits(PackedAlignment);
2441  }
2442  // Packed attribute forces max field alignment to be 1.
2443  if (RD->hasAttr<PackedAttr>())
2444  MaxFieldAlignment = CharUnits::One();
2445 
2446  // Try to respect the external layout if present.
2447  UseExternalLayout = false;
2448  if (ExternalASTSource *Source = Context.getExternalSource())
2449  UseExternalLayout = Source->layoutRecordType(
2450  RD, External.Size, External.Align, External.FieldOffsets,
2451  External.BaseOffsets, External.VirtualBaseOffsets);
2452 }
2453 
2454 void
2455 MicrosoftRecordLayoutBuilder::initializeCXXLayout(const CXXRecordDecl *RD) {
2456  EndsWithZeroSizedObject = false;
2457  LeadsWithZeroSizedBase = false;
2458  HasOwnVFPtr = false;
2459  HasVBPtr = false;
2460  PrimaryBase = nullptr;
2461  SharedVBPtrBase = nullptr;
2462  // Calculate pointer size and alignment. These are used for vfptr and vbprt
2463  // injection.
2464  PointerInfo.Size =
2465  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
2466  PointerInfo.Alignment =
2467  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
2468  // Respect pragma pack.
2469  if (!MaxFieldAlignment.isZero())
2470  PointerInfo.Alignment = std::min(PointerInfo.Alignment, MaxFieldAlignment);
2471 }
2472 
2473 void
2474 MicrosoftRecordLayoutBuilder::layoutNonVirtualBases(const CXXRecordDecl *RD) {
2475  // The MS-ABI lays out all bases that contain leading vfptrs before it lays
2476  // out any bases that do not contain vfptrs. We implement this as two passes
2477  // over the bases. This approach guarantees that the primary base is laid out
2478  // first. We use these passes to calculate some additional aggregated
2479  // information about the bases, such as required alignment and the presence of
2480  // zero sized members.
2481  const ASTRecordLayout *PreviousBaseLayout = nullptr;
2482  // Iterate through the bases and lay out the non-virtual ones.
2483  for (const CXXBaseSpecifier &Base : RD->bases()) {
2484  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2485  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2486  // Mark and skip virtual bases.
2487  if (Base.isVirtual()) {
2488  HasVBPtr = true;
2489  continue;
2490  }
2491  // Check for a base to share a VBPtr with.
2492  if (!SharedVBPtrBase && BaseLayout.hasVBPtr()) {
2493  SharedVBPtrBase = BaseDecl;
2494  HasVBPtr = true;
2495  }
2496  // Only lay out bases with extendable VFPtrs on the first pass.
2497  if (!BaseLayout.hasExtendableVFPtr())
2498  continue;
2499  // If we don't have a primary base, this one qualifies.
2500  if (!PrimaryBase) {
2501  PrimaryBase = BaseDecl;
2502  LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
2503  }
2504  // Lay out the base.
2505  layoutNonVirtualBase(RD, BaseDecl, BaseLayout, PreviousBaseLayout);
2506  }
2507  // Figure out if we need a fresh VFPtr for this class.
2508  if (!PrimaryBase && RD->isDynamicClass())
2510  e = RD->method_end();
2511  !HasOwnVFPtr && i != e; ++i)
2512  HasOwnVFPtr = i->isVirtual() && i->size_overridden_methods() == 0;
2513  // If we don't have a primary base then we have a leading object that could
2514  // itself lead with a zero-sized object, something we track.
2515  bool CheckLeadingLayout = !PrimaryBase;
2516  // Iterate through the bases and lay out the non-virtual ones.
2517  for (const CXXBaseSpecifier &Base : RD->bases()) {
2518  if (Base.isVirtual())
2519  continue;
2520  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2521  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2522  // Only lay out bases without extendable VFPtrs on the second pass.
2523  if (BaseLayout.hasExtendableVFPtr()) {
2524  VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
2525  continue;
2526  }
2527  // If this is the first layout, check to see if it leads with a zero sized
2528  // object. If it does, so do we.
2529  if (CheckLeadingLayout) {
2530  CheckLeadingLayout = false;
2531  LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
2532  }
2533  // Lay out the base.
2534  layoutNonVirtualBase(RD, BaseDecl, BaseLayout, PreviousBaseLayout);
2535  VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
2536  }
2537  // Set our VBPtroffset if we know it at this point.
2538  if (!HasVBPtr)
2539  VBPtrOffset = CharUnits::fromQuantity(-1);
2540  else if (SharedVBPtrBase) {
2541  const ASTRecordLayout &Layout = Context.getASTRecordLayout(SharedVBPtrBase);
2542  VBPtrOffset = Bases[SharedVBPtrBase] + Layout.getVBPtrOffset();
2543  }
2544 }
2545 
2546 static bool recordUsesEBO(const RecordDecl *RD) {
2547  if (!isa<CXXRecordDecl>(RD))
2548  return false;
2549  if (RD->hasAttr<EmptyBasesAttr>())
2550  return true;
2551  if (auto *LVA = RD->getAttr<LayoutVersionAttr>())
2552  // TODO: Double check with the next version of MSVC.
2553  if (LVA->getVersion() <= LangOptions::MSVC2015)
2554  return false;
2555  // TODO: Some later version of MSVC will change the default behavior of the
2556  // compiler to enable EBO by default. When this happens, we will need an
2557  // additional isCompatibleWithMSVC check.
2558  return false;
2559 }
2560 
2561 void MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(
2562  const CXXRecordDecl *RD,
2563  const CXXRecordDecl *BaseDecl,
2564  const ASTRecordLayout &BaseLayout,
2565  const ASTRecordLayout *&PreviousBaseLayout) {
2566  // Insert padding between two bases if the left first one is zero sized or
2567  // contains a zero sized subobject and the right is zero sized or one leads
2568  // with a zero sized base.
2569  bool MDCUsesEBO = recordUsesEBO(RD);
2570  if (PreviousBaseLayout && PreviousBaseLayout->endsWithZeroSizedObject() &&
2571  BaseLayout.leadsWithZeroSizedBase() && !MDCUsesEBO)
2572  Size++;
2573  ElementInfo Info = getAdjustedElementInfo(BaseLayout);
2574  CharUnits BaseOffset;
2575 
2576  // Respect the external AST source base offset, if present.
2577  bool FoundBase = false;
2578  if (UseExternalLayout) {
2579  FoundBase = External.getExternalNVBaseOffset(BaseDecl, BaseOffset);
2580  if (FoundBase) {
2581  assert(BaseOffset >= Size && "base offset already allocated");
2582  Size = BaseOffset;
2583  }
2584  }
2585 
2586  if (!FoundBase) {
2587  if (MDCUsesEBO && BaseDecl->isEmpty() &&
2588  BaseLayout.getNonVirtualSize() == CharUnits::Zero()) {
2589  BaseOffset = CharUnits::Zero();
2590  } else {
2591  // Otherwise, lay the base out at the end of the MDC.
2592  BaseOffset = Size = Size.alignTo(Info.Alignment);
2593  }
2594  }
2595  Bases.insert(std::make_pair(BaseDecl, BaseOffset));
2596  Size += BaseLayout.getNonVirtualSize();
2597  PreviousBaseLayout = &BaseLayout;
2598 }
2599 
2600 void MicrosoftRecordLayoutBuilder::layoutFields(const RecordDecl *RD) {
2601  LastFieldIsNonZeroWidthBitfield = false;
2602  for (const FieldDecl *Field : RD->fields())
2603  layoutField(Field);
2604 }
2605 
2606 void MicrosoftRecordLayoutBuilder::layoutField(const FieldDecl *FD) {
2607  if (FD->isBitField()) {
2608  layoutBitField(FD);
2609  return;
2610  }
2611  LastFieldIsNonZeroWidthBitfield = false;
2612  ElementInfo Info = getAdjustedElementInfo(FD);
2613  Alignment = std::max(Alignment, Info.Alignment);
2614  if (IsUnion) {
2615  placeFieldAtOffset(CharUnits::Zero());
2616  Size = std::max(Size, Info.Size);
2617  } else {
2618  CharUnits FieldOffset;
2619  if (UseExternalLayout) {
2620  FieldOffset =
2621  Context.toCharUnitsFromBits(External.getExternalFieldOffset(FD));
2622  assert(FieldOffset >= Size && "field offset already allocated");
2623  } else {
2624  FieldOffset = Size.alignTo(Info.Alignment);
2625  }
2626  placeFieldAtOffset(FieldOffset);
2627  Size = FieldOffset + Info.Size;
2628  }
2629 }
2630 
2631 void MicrosoftRecordLayoutBuilder::layoutBitField(const FieldDecl *FD) {
2632  unsigned Width = FD->getBitWidthValue(Context);
2633  if (Width == 0) {
2634  layoutZeroWidthBitField(FD);
2635  return;
2636  }
2637  ElementInfo Info = getAdjustedElementInfo(FD);
2638  // Clamp the bitfield to a containable size for the sake of being able
2639  // to lay them out. Sema will throw an error.
2640  if (Width > Context.toBits(Info.Size))
2641  Width = Context.toBits(Info.Size);
2642  // Check to see if this bitfield fits into an existing allocation. Note:
2643  // MSVC refuses to pack bitfields of formal types with different sizes
2644  // into the same allocation.
2645  if (!IsUnion && LastFieldIsNonZeroWidthBitfield &&
2646  CurrentBitfieldSize == Info.Size && Width <= RemainingBitsInField) {
2647  placeFieldAtBitOffset(Context.toBits(Size) - RemainingBitsInField);
2648  RemainingBitsInField -= Width;
2649  return;
2650  }
2651  LastFieldIsNonZeroWidthBitfield = true;
2652  CurrentBitfieldSize = Info.Size;
2653  if (IsUnion) {
2654  placeFieldAtOffset(CharUnits::Zero());
2655  Size = std::max(Size, Info.Size);
2656  // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
2657  } else {
2658  // Allocate a new block of memory and place the bitfield in it.
2659  CharUnits FieldOffset = Size.alignTo(Info.Alignment);
2660  placeFieldAtOffset(FieldOffset);
2661  Size = FieldOffset + Info.Size;
2662  Alignment = std::max(Alignment, Info.Alignment);
2663  RemainingBitsInField = Context.toBits(Info.Size) - Width;
2664  }
2665 }
2666 
2667 void
2668 MicrosoftRecordLayoutBuilder::layoutZeroWidthBitField(const FieldDecl *FD) {
2669  // Zero-width bitfields are ignored unless they follow a non-zero-width
2670  // bitfield.
2671  if (!LastFieldIsNonZeroWidthBitfield) {
2672  placeFieldAtOffset(IsUnion ? CharUnits::Zero() : Size);
2673  // TODO: Add a Sema warning that MS ignores alignment for zero
2674  // sized bitfields that occur after zero-size bitfields or non-bitfields.
2675  return;
2676  }
2677  LastFieldIsNonZeroWidthBitfield = false;
2678  ElementInfo Info = getAdjustedElementInfo(FD);
2679  if (IsUnion) {
2680  placeFieldAtOffset(CharUnits::Zero());
2681  Size = std::max(Size, Info.Size);
2682  // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
2683  } else {
2684  // Round up the current record size to the field's alignment boundary.
2685  CharUnits FieldOffset = Size.alignTo(Info.Alignment);
2686  placeFieldAtOffset(FieldOffset);
2687  Size = FieldOffset;
2688  Alignment = std::max(Alignment, Info.Alignment);
2689  }
2690 }
2691 
2692 void MicrosoftRecordLayoutBuilder::injectVBPtr(const CXXRecordDecl *RD) {
2693  if (!HasVBPtr || SharedVBPtrBase)
2694  return;
2695  // Inject the VBPointer at the injection site.
2696  CharUnits InjectionSite = VBPtrOffset;
2697  // But before we do, make sure it's properly aligned.
2698  VBPtrOffset = VBPtrOffset.alignTo(PointerInfo.Alignment);
2699  // Shift everything after the vbptr down, unless we're using an external
2700  // layout.
2701  if (UseExternalLayout)
2702  return;
2703  // Determine where the first field should be laid out after the vbptr.
2704  CharUnits FieldStart = VBPtrOffset + PointerInfo.Size;
2705  // Make sure that the amount we push the fields back by is a multiple of the
2706  // alignment.
2707  CharUnits Offset = (FieldStart - InjectionSite)
2708  .alignTo(std::max(RequiredAlignment, Alignment));
2709  Size += Offset;
2710  for (uint64_t &FieldOffset : FieldOffsets)
2711  FieldOffset += Context.toBits(Offset);
2712  for (BaseOffsetsMapTy::value_type &Base : Bases)
2713  if (Base.second >= InjectionSite)
2714  Base.second += Offset;
2715 }
2716 
2717 void MicrosoftRecordLayoutBuilder::injectVFPtr(const CXXRecordDecl *RD) {
2718  if (!HasOwnVFPtr)
2719  return;
2720  // Make sure that the amount we push the struct back by is a multiple of the
2721  // alignment.
2722  CharUnits Offset =
2723  PointerInfo.Size.alignTo(std::max(RequiredAlignment, Alignment));
2724  // Push back the vbptr, but increase the size of the object and push back
2725  // regular fields by the offset only if not using external record layout.
2726  if (HasVBPtr)
2727  VBPtrOffset += Offset;
2728 
2729  if (UseExternalLayout)
2730  return;
2731 
2732  Size += Offset;
2733 
2734  // If we're using an external layout, the fields offsets have already
2735  // accounted for this adjustment.
2736  for (uint64_t &FieldOffset : FieldOffsets)
2737  FieldOffset += Context.toBits(Offset);
2738  for (BaseOffsetsMapTy::value_type &Base : Bases)
2739  Base.second += Offset;
2740 }
2741 
2742 void MicrosoftRecordLayoutBuilder::layoutVirtualBases(const CXXRecordDecl *RD) {
2743  if (!HasVBPtr)
2744  return;
2745  // Vtordisps are always 4 bytes (even in 64-bit mode)
2746  CharUnits VtorDispSize = CharUnits::fromQuantity(4);
2747  CharUnits VtorDispAlignment = VtorDispSize;
2748  // vtordisps respect pragma pack.
2749  if (!MaxFieldAlignment.isZero())
2750  VtorDispAlignment = std::min(VtorDispAlignment, MaxFieldAlignment);
2751  // The alignment of the vtordisp is at least the required alignment of the
2752  // entire record. This requirement may be present to support vtordisp
2753  // injection.
2754  for (const CXXBaseSpecifier &VBase : RD->vbases()) {
2755  const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
2756  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2757  RequiredAlignment =
2758  std::max(RequiredAlignment, BaseLayout.getRequiredAlignment());
2759  }
2760  VtorDispAlignment = std::max(VtorDispAlignment, RequiredAlignment);
2761  // Compute the vtordisp set.
2762  llvm::SmallPtrSet<const CXXRecordDecl *, 2> HasVtorDispSet;
2763  computeVtorDispSet(HasVtorDispSet, RD);
2764  // Iterate through the virtual bases and lay them out.
2765  const ASTRecordLayout *PreviousBaseLayout = nullptr;
2766  for (const CXXBaseSpecifier &VBase : RD->vbases()) {
2767  const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
2768  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2769  bool HasVtordisp = HasVtorDispSet.count(BaseDecl) > 0;
2770  // Insert padding between two bases if the left first one is zero sized or
2771  // contains a zero sized subobject and the right is zero sized or one leads
2772  // with a zero sized base. The padding between virtual bases is 4
2773  // bytes (in both 32 and 64 bits modes) and always involves rounding up to
2774  // the required alignment, we don't know why.
2775  if ((PreviousBaseLayout && PreviousBaseLayout->endsWithZeroSizedObject() &&
2776  BaseLayout.leadsWithZeroSizedBase() && !recordUsesEBO(RD)) ||
2777  HasVtordisp) {
2778  Size = Size.alignTo(VtorDispAlignment) + VtorDispSize;
2779  Alignment = std::max(VtorDispAlignment, Alignment);
2780  }
2781  // Insert the virtual base.
2782  ElementInfo Info = getAdjustedElementInfo(BaseLayout);
2783  CharUnits BaseOffset;
2784 
2785  // Respect the external AST source base offset, if present.
2786  bool FoundBase = false;
2787  if (UseExternalLayout) {
2788  FoundBase = External.getExternalVBaseOffset(BaseDecl, BaseOffset);
2789  if (FoundBase)
2790  assert(BaseOffset >= Size && "base offset already allocated");
2791  }
2792  if (!FoundBase)
2793  BaseOffset = Size.alignTo(Info.Alignment);
2794 
2795  VBases.insert(std::make_pair(BaseDecl,
2796  ASTRecordLayout::VBaseInfo(BaseOffset, HasVtordisp)));
2797  Size = BaseOffset + BaseLayout.getNonVirtualSize();
2798  PreviousBaseLayout = &BaseLayout;
2799  }
2800 }
2801 
2802 void MicrosoftRecordLayoutBuilder::finalizeLayout(const RecordDecl *RD) {
2803  // Respect required alignment. Note that in 32-bit mode Required alignment
2804  // may be 0 and cause size not to be updated.
2805  DataSize = Size;
2806  if (!RequiredAlignment.isZero()) {
2807  Alignment = std::max(Alignment, RequiredAlignment);
2808  auto RoundingAlignment = Alignment;
2809  if (!MaxFieldAlignment.isZero())
2810  RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
2811  RoundingAlignment = std::max(RoundingAlignment, RequiredAlignment);
2812  Size = Size.alignTo(RoundingAlignment);
2813  }
2814  if (Size.isZero()) {
2815  if (!recordUsesEBO(RD) || !cast<CXXRecordDecl>(RD)->isEmpty()) {
2816  EndsWithZeroSizedObject = true;
2817  LeadsWithZeroSizedBase = true;
2818  }
2819  // Zero-sized structures have size equal to their alignment if a
2820  // __declspec(align) came into play.
2821  if (RequiredAlignment >= MinEmptyStructSize)
2822  Size = Alignment;
2823  else
2824  Size = MinEmptyStructSize;
2825  }
2826 
2827  if (UseExternalLayout) {
2828  Size = Context.toCharUnitsFromBits(External.Size);
2829  if (External.Align)
2830  Alignment = Context.toCharUnitsFromBits(External.Align);
2831  }
2832 }
2833 
2834 // Recursively walks the non-virtual bases of a class and determines if any of
2835 // them are in the bases with overridden methods set.
2836 static bool
2837 RequiresVtordisp(const llvm::SmallPtrSetImpl<const CXXRecordDecl *> &
2838  BasesWithOverriddenMethods,
2839  const CXXRecordDecl *RD) {
2840  if (BasesWithOverriddenMethods.count(RD))
2841  return true;
2842  // If any of a virtual bases non-virtual bases (recursively) requires a
2843  // vtordisp than so does this virtual base.
2844  for (const CXXBaseSpecifier &Base : RD->bases())
2845  if (!Base.isVirtual() &&
2846  RequiresVtordisp(BasesWithOverriddenMethods,
2847  Base.getType()->getAsCXXRecordDecl()))
2848  return true;
2849  return false;
2850 }
2851 
2852 void MicrosoftRecordLayoutBuilder::computeVtorDispSet(
2853  llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtordispSet,
2854  const CXXRecordDecl *RD) const {
2855  // /vd2 or #pragma vtordisp(2): Always use vtordisps for virtual bases with
2856  // vftables.
2857  if (RD->getMSVtorDispMode() == MSVtorDispAttr::ForVFTable) {
2858  for (const CXXBaseSpecifier &Base : RD->vbases()) {
2859  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2860  const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
2861  if (Layout.hasExtendableVFPtr())
2862  HasVtordispSet.insert(BaseDecl);
2863  }
2864  return;
2865  }
2866 
2867  // If any of our bases need a vtordisp for this type, so do we. Check our
2868  // direct bases for vtordisp requirements.
2869  for (const CXXBaseSpecifier &Base : RD->bases()) {
2870  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2871  const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
2872  for (const auto &bi : Layout.getVBaseOffsetsMap())
2873  if (bi.second.hasVtorDisp())
2874  HasVtordispSet.insert(bi.first);
2875  }
2876  // We don't introduce any additional vtordisps if either:
2877  // * A user declared constructor or destructor aren't declared.
2878  // * #pragma vtordisp(0) or the /vd0 flag are in use.
2879  if ((!RD->hasUserDeclaredConstructor() && !RD->hasUserDeclaredDestructor()) ||
2880  RD->getMSVtorDispMode() == MSVtorDispAttr::Never)
2881  return;
2882  // /vd1 or #pragma vtordisp(1): Try to guess based on whether we think it's
2883  // possible for a partially constructed object with virtual base overrides to
2884  // escape a non-trivial constructor.
2885  assert(RD->getMSVtorDispMode() == MSVtorDispAttr::ForVBaseOverride);
2886  // Compute a set of base classes which define methods we override. A virtual
2887  // base in this set will require a vtordisp. A virtual base that transitively
2888  // contains one of these bases as a non-virtual base will also require a
2889  // vtordisp.
2890  llvm::SmallPtrSet<const CXXMethodDecl *, 8> Work;
2891  llvm::SmallPtrSet<const CXXRecordDecl *, 2> BasesWithOverriddenMethods;
2892  // Seed the working set with our non-destructor, non-pure virtual methods.
2893  for (const CXXMethodDecl *MD : RD->methods())
2894  if (MD->isVirtual() && !isa<CXXDestructorDecl>(MD) && !MD->isPure())
2895  Work.insert(MD);
2896  while (!Work.empty()) {
2897  const CXXMethodDecl *MD = *Work.begin();
2899  e = MD->end_overridden_methods();
2900  // If a virtual method has no-overrides it lives in its parent's vtable.
2901  if (i == e)
2902  BasesWithOverriddenMethods.insert(MD->getParent());
2903  else
2904  Work.insert(i, e);
2905  // We've finished processing this element, remove it from the working set.
2906  Work.erase(MD);
2907  }
2908  // For each of our virtual bases, check if it is in the set of overridden
2909  // bases or if it transitively contains a non-virtual base that is.
2910  for (const CXXBaseSpecifier &Base : RD->vbases()) {
2911  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2912  if (!HasVtordispSet.count(BaseDecl) &&
2913  RequiresVtordisp(BasesWithOverriddenMethods, BaseDecl))
2914  HasVtordispSet.insert(BaseDecl);
2915  }
2916 }
2917 
2918 /// getASTRecordLayout - Get or compute information about the layout of the
2919 /// specified record (struct/union/class), which indicates its size and field
2920 /// position information.
2921 const ASTRecordLayout &
2923  // These asserts test different things. A record has a definition
2924  // as soon as we begin to parse the definition. That definition is
2925  // not a complete definition (which is what isDefinition() tests)
2926  // until we *finish* parsing the definition.
2927 
2928  if (D->hasExternalLexicalStorage() && !D->getDefinition())
2929  getExternalSource()->CompleteType(const_cast<RecordDecl*>(D));
2930 
2931  D = D->getDefinition();
2932  assert(D && "Cannot get layout of forward declarations!");
2933  assert(!D->isInvalidDecl() && "Cannot get layout of invalid decl!");
2934  assert(D->isCompleteDefinition() && "Cannot layout type before complete!");
2935 
2936  // Look up this layout, if already laid out, return what we have.
2937  // Note that we can't save a reference to the entry because this function
2938  // is recursive.
2939  const ASTRecordLayout *Entry = ASTRecordLayouts[D];
2940  if (Entry) return *Entry;
2941 
2942  const ASTRecordLayout *NewEntry = nullptr;
2943 
2944  if (isMsLayout(*this)) {
2945  MicrosoftRecordLayoutBuilder Builder(*this);
2946  if (const auto *RD = dyn_cast<CXXRecordDecl>(D)) {
2947  Builder.cxxLayout(RD);
2948  NewEntry = new (*this) ASTRecordLayout(
2949  *this, Builder.Size, Builder.Alignment, Builder.RequiredAlignment,
2950  Builder.HasOwnVFPtr, Builder.HasOwnVFPtr || Builder.PrimaryBase,
2951  Builder.VBPtrOffset, Builder.DataSize, Builder.FieldOffsets,
2952  Builder.NonVirtualSize, Builder.Alignment, CharUnits::Zero(),
2953  Builder.PrimaryBase, false, Builder.SharedVBPtrBase,
2954  Builder.EndsWithZeroSizedObject, Builder.LeadsWithZeroSizedBase,
2955  Builder.Bases, Builder.VBases);
2956  } else {
2957  Builder.layout(D);
2958  NewEntry = new (*this) ASTRecordLayout(
2959  *this, Builder.Size, Builder.Alignment, Builder.RequiredAlignment,
2960  Builder.Size, Builder.FieldOffsets);
2961  }
2962  } else {
2963  if (const auto *RD = dyn_cast<CXXRecordDecl>(D)) {
2964  EmptySubobjectMap EmptySubobjects(*this, RD);
2965  ItaniumRecordLayoutBuilder Builder(*this, &EmptySubobjects);
2966  Builder.Layout(RD);
2967 
2968  // In certain situations, we are allowed to lay out objects in the
2969  // tail-padding of base classes. This is ABI-dependent.
2970  // FIXME: this should be stored in the record layout.
2971  bool skipTailPadding =
2972  mustSkipTailPadding(getTargetInfo().getCXXABI(), RD);
2973 
2974  // FIXME: This should be done in FinalizeLayout.
2975  CharUnits DataSize =
2976  skipTailPadding ? Builder.getSize() : Builder.getDataSize();
2977  CharUnits NonVirtualSize =
2978  skipTailPadding ? DataSize : Builder.NonVirtualSize;
2979  NewEntry = new (*this) ASTRecordLayout(
2980  *this, Builder.getSize(), Builder.Alignment,
2981  /*RequiredAlignment : used by MS-ABI)*/
2982  Builder.Alignment, Builder.HasOwnVFPtr, RD->isDynamicClass(),
2983  CharUnits::fromQuantity(-1), DataSize, Builder.FieldOffsets,
2984  NonVirtualSize, Builder.NonVirtualAlignment,
2985  EmptySubobjects.SizeOfLargestEmptySubobject, Builder.PrimaryBase,
2986  Builder.PrimaryBaseIsVirtual, nullptr, false, false, Builder.Bases,
2987  Builder.VBases);
2988  } else {
2989  ItaniumRecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
2990  Builder.Layout(D);
2991 
2992  NewEntry = new (*this) ASTRecordLayout(
2993  *this, Builder.getSize(), Builder.Alignment,
2994  /*RequiredAlignment : used by MS-ABI)*/
2995  Builder.Alignment, Builder.getSize(), Builder.FieldOffsets);
2996  }
2997  }
2998 
2999  ASTRecordLayouts[D] = NewEntry;
3000 
3001  if (getLangOpts().DumpRecordLayouts) {
3002  llvm::outs() << "\n*** Dumping AST Record Layout\n";
3003  DumpRecordLayout(D, llvm::outs(), getLangOpts().DumpRecordLayoutsSimple);
3004  }
3005 
3006  return *NewEntry;
3007 }
3008 
3010  if (!getTargetInfo().getCXXABI().hasKeyFunctions())
3011  return nullptr;
3012 
3013  assert(RD->getDefinition() && "Cannot get key function for forward decl!");
3014  RD = cast<CXXRecordDecl>(RD->getDefinition());
3015 
3016  // Beware:
3017  // 1) computing the key function might trigger deserialization, which might
3018  // invalidate iterators into KeyFunctions
3019  // 2) 'get' on the LazyDeclPtr might also trigger deserialization and
3020  // invalidate the LazyDeclPtr within the map itself
3021  LazyDeclPtr Entry = KeyFunctions[RD];
3022  const Decl *Result =
3023  Entry ? Entry.get(getExternalSource()) : computeKeyFunction(*this, RD);
3024 
3025  // Store it back if it changed.
3026  if (Entry.isOffset() || Entry.isValid() != bool(Result))
3027  KeyFunctions[RD] = const_cast<Decl*>(Result);
3028 
3029  return cast_or_null<CXXMethodDecl>(Result);
3030 }
3031 
3033  assert(Method == Method->getFirstDecl() &&
3034  "not working with method declaration from class definition");
3035 
3036  // Look up the cache entry. Since we're working with the first
3037  // declaration, its parent must be the class definition, which is
3038  // the correct key for the KeyFunctions hash.
3039  const auto &Map = KeyFunctions;
3040  auto I = Map.find(Method->getParent());
3041 
3042  // If it's not cached, there's nothing to do.
3043  if (I == Map.end()) return;
3044 
3045  // If it is cached, check whether it's the target method, and if so,
3046  // remove it from the cache. Note, the call to 'get' might invalidate
3047  // the iterator and the LazyDeclPtr object within the map.
3048  LazyDeclPtr Ptr = I->second;
3049  if (Ptr.get(getExternalSource()) == Method) {
3050  // FIXME: remember that we did this for module / chained PCH state?
3051  KeyFunctions.erase(Method->getParent());
3052  }
3053 }
3054 
3055 static uint64_t getFieldOffset(const ASTContext &C, const FieldDecl *FD) {
3056  const ASTRecordLayout &Layout = C.getASTRecordLayout(FD->getParent());
3057  return Layout.getFieldOffset(FD->getFieldIndex());
3058 }
3059 
3060 uint64_t ASTContext::getFieldOffset(const ValueDecl *VD) const {
3061  uint64_t OffsetInBits;
3062  if (const FieldDecl *FD = dyn_cast<FieldDecl>(VD)) {
3063  OffsetInBits = ::getFieldOffset(*this, FD);
3064  } else {
3065  const IndirectFieldDecl *IFD = cast<IndirectFieldDecl>(VD);
3066 
3067  OffsetInBits = 0;
3068  for (const NamedDecl *ND : IFD->chain())
3069  OffsetInBits += ::getFieldOffset(*this, cast<FieldDecl>(ND));
3070  }
3071 
3072  return OffsetInBits;
3073 }
3074 
3076  const ObjCImplementationDecl *ID,
3077  const ObjCIvarDecl *Ivar) const {
3078  const ObjCInterfaceDecl *Container = Ivar->getContainingInterface();
3079 
3080  // FIXME: We should eliminate the need to have ObjCImplementationDecl passed
3081  // in here; it should never be necessary because that should be the lexical
3082  // decl context for the ivar.
3083 
3084  // If we know have an implementation (and the ivar is in it) then
3085  // look up in the implementation layout.
3086  const ASTRecordLayout *RL;
3087  if (ID && declaresSameEntity(ID->getClassInterface(), Container))
3088  RL = &getASTObjCImplementationLayout(ID);
3089  else
3090  RL = &getASTObjCInterfaceLayout(Container);
3091 
3092  // Compute field index.
3093  //
3094  // FIXME: The index here is closely tied to how ASTContext::getObjCLayout is
3095  // implemented. This should be fixed to get the information from the layout
3096  // directly.
3097  unsigned Index = 0;
3098 
3099  for (const ObjCIvarDecl *IVD = Container->all_declared_ivar_begin();
3100  IVD; IVD = IVD->getNextIvar()) {
3101  if (Ivar == IVD)
3102  break;
3103  ++Index;
3104  }
3105  assert(Index < RL->getFieldCount() && "Ivar is not inside record layout!");
3106 
3107  return RL->getFieldOffset(Index);
3108 }
3109 
3110 /// getObjCLayout - Get or compute information about the layout of the
3111 /// given interface.
3112 ///
3113 /// \param Impl - If given, also include the layout of the interface's
3114 /// implementation. This may differ by including synthesized ivars.
3115 const ASTRecordLayout &
3116 ASTContext::getObjCLayout(const ObjCInterfaceDecl *D,
3117  const ObjCImplementationDecl *Impl) const {
3118  // Retrieve the definition
3119  if (D->hasExternalLexicalStorage() && !D->getDefinition())
3120  getExternalSource()->CompleteType(const_cast<ObjCInterfaceDecl*>(D));
3121  D = D->getDefinition();
3122  assert(D && D->isThisDeclarationADefinition() && "Invalid interface decl!");
3123 
3124  // Look up this layout, if already laid out, return what we have.
3125  const ObjCContainerDecl *Key =
3126  Impl ? (const ObjCContainerDecl*) Impl : (const ObjCContainerDecl*) D;
3127  if (const ASTRecordLayout *Entry = ObjCLayouts[Key])
3128  return *Entry;
3129 
3130  // Add in synthesized ivar count if laying out an implementation.
3131  if (Impl) {
3132  unsigned SynthCount = CountNonClassIvars(D);
3133  // If there aren't any synthesized ivars then reuse the interface
3134  // entry. Note we can't cache this because we simply free all
3135  // entries later; however we shouldn't look up implementations
3136  // frequently.
3137  if (SynthCount == 0)
3138  return getObjCLayout(D, nullptr);
3139  }
3140 
3141  ItaniumRecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
3142  Builder.Layout(D);
3143 
3144  const ASTRecordLayout *NewEntry =
3145  new (*this) ASTRecordLayout(*this, Builder.getSize(),
3146  Builder.Alignment,
3147  /*RequiredAlignment : used by MS-ABI)*/
3148  Builder.Alignment,
3149  Builder.getDataSize(),
3150  Builder.FieldOffsets);
3151 
3152  ObjCLayouts[Key] = NewEntry;
3153 
3154  return *NewEntry;
3155 }
3156 
3157 static void PrintOffset(raw_ostream &OS,
3158  CharUnits Offset, unsigned IndentLevel) {
3159  OS << llvm::format("%10" PRId64 " | ", (int64_t)Offset.getQuantity());
3160  OS.indent(IndentLevel * 2);
3161 }
3162 
3163 static void PrintBitFieldOffset(raw_ostream &OS, CharUnits Offset,
3164  unsigned Begin, unsigned Width,
3165  unsigned IndentLevel) {
3166  llvm::SmallString<10> Buffer;
3167  {
3168  llvm::raw_svector_ostream BufferOS(Buffer);
3169  BufferOS << Offset.getQuantity() << ':';
3170  if (Width == 0) {
3171  BufferOS << '-';
3172  } else {
3173  BufferOS << Begin << '-' << (Begin + Width - 1);
3174  }
3175  }
3176 
3177  OS << llvm::right_justify(Buffer, 10) << " | ";
3178  OS.indent(IndentLevel * 2);
3179 }
3180 
3181 static void PrintIndentNoOffset(raw_ostream &OS, unsigned IndentLevel) {
3182  OS << " | ";
3183  OS.indent(IndentLevel * 2);
3184 }
3185 
3186 static void DumpRecordLayout(raw_ostream &OS, const RecordDecl *RD,
3187  const ASTContext &C,
3188  CharUnits Offset,
3189  unsigned IndentLevel,
3190  const char* Description,
3191  bool PrintSizeInfo,
3192  bool IncludeVirtualBases) {
3193  const ASTRecordLayout &Layout = C.getASTRecordLayout(RD);
3194  auto CXXRD = dyn_cast<CXXRecordDecl>(RD);
3195 
3196  PrintOffset(OS, Offset, IndentLevel);
3197  OS << C.getTypeDeclType(const_cast<RecordDecl*>(RD)).getAsString();
3198  if (Description)
3199  OS << ' ' << Description;
3200  if (CXXRD && CXXRD->isEmpty())
3201  OS << " (empty)";
3202  OS << '\n';
3203 
3204  IndentLevel++;
3205 
3206  // Dump bases.
3207  if (CXXRD) {
3208  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
3209  bool HasOwnVFPtr = Layout.hasOwnVFPtr();
3210  bool HasOwnVBPtr = Layout.hasOwnVBPtr();
3211 
3212  // Vtable pointer.
3213  if (CXXRD->isDynamicClass() && !PrimaryBase && !isMsLayout(C)) {
3214  PrintOffset(OS, Offset, IndentLevel);
3215  OS << '(' << *RD << " vtable pointer)\n";
3216  } else if (HasOwnVFPtr) {
3217  PrintOffset(OS, Offset, IndentLevel);
3218  // vfptr (for Microsoft C++ ABI)
3219  OS << '(' << *RD << " vftable pointer)\n";
3220  }
3221 
3222  // Collect nvbases.
3224  for (const CXXBaseSpecifier &Base : CXXRD->bases()) {
3225  assert(!Base.getType()->isDependentType() &&
3226  "Cannot layout class with dependent bases.");
3227  if (!Base.isVirtual())
3228  Bases.push_back(Base.getType()->getAsCXXRecordDecl());
3229  }
3230 
3231  // Sort nvbases by offset.
3232  std::stable_sort(Bases.begin(), Bases.end(),
3233  [&](const CXXRecordDecl *L, const CXXRecordDecl *R) {
3234  return Layout.getBaseClassOffset(L) < Layout.getBaseClassOffset(R);
3235  });
3236 
3237  // Dump (non-virtual) bases
3238  for (const CXXRecordDecl *Base : Bases) {
3239  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base);
3240  DumpRecordLayout(OS, Base, C, BaseOffset, IndentLevel,
3241  Base == PrimaryBase ? "(primary base)" : "(base)",
3242  /*PrintSizeInfo=*/false,
3243  /*IncludeVirtualBases=*/false);
3244  }
3245 
3246  // vbptr (for Microsoft C++ ABI)
3247  if (HasOwnVBPtr) {
3248  PrintOffset(OS, Offset + Layout.getVBPtrOffset(), IndentLevel);
3249  OS << '(' << *RD << " vbtable pointer)\n";
3250  }
3251  }
3252 
3253  // Dump fields.
3254  uint64_t FieldNo = 0;
3255  for (RecordDecl::field_iterator I = RD->field_begin(),
3256  E = RD->field_end(); I != E; ++I, ++FieldNo) {
3257  const FieldDecl &Field = **I;
3258  uint64_t LocalFieldOffsetInBits = Layout.getFieldOffset(FieldNo);
3259  CharUnits FieldOffset =
3260  Offset + C.toCharUnitsFromBits(LocalFieldOffsetInBits);
3261 
3262  // Recursively dump fields of record type.
3263  if (auto RT = Field.getType()->getAs<RecordType>()) {
3264  DumpRecordLayout(OS, RT->getDecl(), C, FieldOffset, IndentLevel,
3265  Field.getName().data(),
3266  /*PrintSizeInfo=*/false,
3267  /*IncludeVirtualBases=*/true);
3268  continue;
3269  }
3270 
3271  if (Field.isBitField()) {
3272  uint64_t LocalFieldByteOffsetInBits = C.toBits(FieldOffset - Offset);
3273  unsigned Begin = LocalFieldOffsetInBits - LocalFieldByteOffsetInBits;
3274  unsigned Width = Field.getBitWidthValue(C);
3275  PrintBitFieldOffset(OS, FieldOffset, Begin, Width, IndentLevel);
3276  } else {
3277  PrintOffset(OS, FieldOffset, IndentLevel);
3278  }
3279  OS << Field.getType().getAsString() << ' ' << Field << '\n';
3280  }
3281 
3282  // Dump virtual bases.
3283  if (CXXRD && IncludeVirtualBases) {
3284  const ASTRecordLayout::VBaseOffsetsMapTy &VtorDisps =
3285  Layout.getVBaseOffsetsMap();
3286 
3287  for (const CXXBaseSpecifier &Base : CXXRD->vbases()) {
3288  assert(Base.isVirtual() && "Found non-virtual class!");
3289  const CXXRecordDecl *VBase = Base.getType()->getAsCXXRecordDecl();
3290 
3291  CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBase);
3292 
3293  if (VtorDisps.find(VBase)->second.hasVtorDisp()) {
3294  PrintOffset(OS, VBaseOffset - CharUnits::fromQuantity(4), IndentLevel);
3295  OS << "(vtordisp for vbase " << *VBase << ")\n";
3296  }
3297 
3298  DumpRecordLayout(OS, VBase, C, VBaseOffset, IndentLevel,
3299  VBase == Layout.getPrimaryBase() ?
3300  "(primary virtual base)" : "(virtual base)",
3301  /*PrintSizeInfo=*/false,
3302  /*IncludeVirtualBases=*/false);
3303  }
3304  }
3305 
3306  if (!PrintSizeInfo) return;
3307 
3308  PrintIndentNoOffset(OS, IndentLevel - 1);
3309  OS << "[sizeof=" << Layout.getSize().getQuantity();
3310  if (CXXRD && !isMsLayout(C))
3311  OS << ", dsize=" << Layout.getDataSize().getQuantity();
3312  OS << ", align=" << Layout.getAlignment().getQuantity();
3313 
3314  if (CXXRD) {
3315  OS << ",\n";
3316  PrintIndentNoOffset(OS, IndentLevel - 1);
3317  OS << " nvsize=" << Layout.getNonVirtualSize().getQuantity();
3318  OS << ", nvalign=" << Layout.getNonVirtualAlignment().getQuantity();
3319  }
3320  OS << "]\n";
3321 }
3322 
3324  raw_ostream &OS,
3325  bool Simple) const {
3326  if (!Simple) {
3327  ::DumpRecordLayout(OS, RD, *this, CharUnits(), 0, nullptr,
3328  /*PrintSizeInfo*/true,
3329  /*IncludeVirtualBases=*/true);
3330  return;
3331  }
3332 
3333  // The "simple" format is designed to be parsed by the
3334  // layout-override testing code. There shouldn't be any external
3335  // uses of this format --- when LLDB overrides a layout, it sets up
3336  // the data structures directly --- so feel free to adjust this as
3337  // you like as long as you also update the rudimentary parser for it
3338  // in libFrontend.
3339 
3340  const ASTRecordLayout &Info = getASTRecordLayout(RD);
3341  OS << "Type: " << getTypeDeclType(RD).getAsString() << "\n";
3342  OS << "\nLayout: ";
3343  OS << "<ASTRecordLayout\n";
3344  OS << " Size:" << toBits(Info.getSize()) << "\n";
3345  if (!isMsLayout(*this))
3346  OS << " DataSize:" << toBits(Info.getDataSize()) << "\n";
3347  OS << " Alignment:" << toBits(Info.getAlignment()) << "\n";
3348  OS << " FieldOffsets: [";
3349  for (unsigned i = 0, e = Info.getFieldCount(); i != e; ++i) {
3350  if (i) OS << ", ";
3351  OS << Info.getFieldOffset(i);
3352  }
3353  OS << "]>\n";
3354 }
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
FunctionDecl - An instance of this class is created to represent a function declaration or definition...
Definition: Decl.h:1698
Only allocate objects in the tail padding of a base class if the base class is not POD according to t...
Definition: TargetCXXABI.h:309
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:216
A (possibly-)qualified type.
Definition: Type.h:614
bool isStandardLayout() const
Determine whether this class has standard layout per (C++ [class]p7)
Definition: DeclCXX.h:1300
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:773
const CXXMethodDecl *const * method_iterator
Definition: DeclCXX.h:2073
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:1452
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:435
const llvm::Triple & getTriple() const
Returns the target triple of the primary target.
Definition: TargetInfo.h:782
CharUnits getBaseClassOffset(const CXXRecordDecl *Base) const
getBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:223
unsigned getNumVBases() const
Retrieves the number of virtual base classes of this class.
Definition: DeclCXX.h:788
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:1264
unsigned getFieldIndex() const
getFieldIndex - Returns the index of this field within its record, as appropriate for passing to ASTR...
Definition: Decl.cpp:3625
const RecordDecl * getParent() const
getParent - Returns the parent of this field declaration, which is the struct in which this field is ...
Definition: Decl.h:2642
The base class of the type hierarchy.
Definition: Type.h:1306
DiagnosticsEngine & getDiagnostics() const
DiagnosticBuilder Report(SourceLocation Loc, unsigned DiagID)
Issue the message to the client.
Definition: Diagnostic.h:1205
Represents an array type, per C99 6.7.5.2 - Array Declarators.
Definition: Type.h:2501
bool isZero() const
isZero - Test whether the quantity equals zero.
Definition: CharUnits.h:116
const TargetInfo & getTargetInfo() const
Definition: ASTContext.h:645
CharUnits getAlignment() const
getAlignment - Get the record alignment in characters.
Definition: RecordLayout.h:171
unsigned getCharWidth() const
Definition: TargetInfo.h:333
QualType getElementType() const
Definition: Type.h:2535
bool isCompleteDefinition() const
isCompleteDefinition - Return true if this decl has its body fully specified.
Definition: Decl.h:3091
bool hasVBPtr() const
hasVBPtr - Does this class have a virtual function table pointer.
Definition: RecordLayout.h:276
const T * getAs() const
Member-template getAs<specific type>&#39;.
Definition: Type.h:6105
unsigned getCharAlign() const
Definition: TargetInfo.h:334
The "__interface" keyword.
Definition: Type.h:4552
bool hasOwnVFPtr() const
hasOwnVFPtr - Does this class provide its own virtual-function table pointer, rather than inheriting ...
Definition: RecordLayout.h:250
bool isInvalidDecl() const
Definition: DeclBase.h:546
unsigned getZeroLengthBitfieldBoundary() const
Get the fixed alignment value in bits for a member that follows a zero length bitfield.
Definition: TargetInfo.h:519
bool mayInsertExtraPadding(bool EmitRemark=false) const
Whether we are allowed to insert extra padding between fields.
Definition: Decl.cpp:3971
IdentifierInfo * getIdentifier() const
getIdentifier - Get the identifier that names this declaration, if there is one.
Definition: Decl.h:265
RecordDecl - Represents a struct/union/class.
Definition: Decl.h:3482
uint64_t getPointerWidth(unsigned AddrSpace) const
Return the width of pointers on this target, for the specified address space.
Definition: TargetInfo.h:311
bool isEmpty() const
Determine whether this is an empty class in the sense of (C++11 [meta.unary.prop]).
Definition: DeclCXX.h:1279
TargetCXXABI getCXXABI() const
Get the C++ ABI currently in use.
Definition: TargetInfo.h:851
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:128
RecordDecl * getDefinition() const
getDefinition - Returns the RecordDecl that actually defines this struct/union/class.
Definition: Decl.h:3603
field_range fields() const
Definition: Decl.h:3613
FieldDecl - An instance of this class is created by Sema::ActOnField to represent a member of a struc...
Definition: Decl.h:2461
bool hasUserDeclaredDestructor() const
Determine whether this class has a user-declared destructor.
Definition: DeclCXX.h:1135
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:231
method_iterator method_begin() const
Method begin iterator.
Definition: DeclCXX.h:821
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:3610
bool canKeyFunctionBeInline() const
Can an out-of-line inline function serve as a key function?
Definition: TargetCXXABI.h:266
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:2539
ObjCContainerDecl - Represents a container for method declarations.
Definition: DeclObjC.h:919
TagKind getTagKind() const
Definition: Decl.h:3150
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:285
ArrayRef< NamedDecl * > chain() const
Definition: Decl.h:2727
std::string getAsString() const
Definition: Type.h:944
unsigned Align
Definition: ASTContext.h:118
field_iterator field_begin() const
Definition: Decl.cpp:3924
unsigned getBitWidthValue(const ASTContext &Ctx) const
Definition: Decl.cpp:3620
bool declaresSameEntity(const Decl *D1, const Decl *D2)
Determine whether two declarations declare the same entity.
Definition: DeclBase.h:1149
const VBaseOffsetsMapTy & getVBaseOffsetsMap() const
Definition: RecordLayout.h:306
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:513
Represents an ObjC class declaration.
Definition: DeclObjC.h:1108
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:361
CanQualType UnsignedCharTy
Definition: ASTContext.h:974
lookup_result lookup(DeclarationName Name) const
lookup - Find the declarations (if any) with the given Name in this context.
Definition: DeclBase.cpp:1521
bool hasAttr() const
Definition: DeclBase.h:535
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:953
CXXRecordDecl * getAsCXXRecordDecl() const
Retrieves the CXXRecordDecl that this type refers to, either because the type is a RecordType or beca...
Definition: Type.cpp:1569
bool isDynamicClass() const
Definition: DeclCXX.h:751
bool useExplicitBitFieldAlignment() const
Check whether explicit bitfield alignment attributes should be.
Definition: TargetInfo.h:525
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:1386
method_iterator end_overridden_methods() const
Definition: DeclCXX.cpp:1917
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:3941
bool isInlineSpecified() const
Determine whether the "inline" keyword was specified for this function.
Definition: Decl.h:2239
ValueDecl - Represent the declaration of a variable (in which case it is an lvalue) a function (in wh...
Definition: Decl.h:628
SourceLocation End
const FunctionProtoType * T
bool isNearlyEmpty(const CXXRecordDecl *RD) const
field_iterator field_end() const
Definition: Decl.h:3616
#define bool
Definition: stdbool.h:31
CharUnits getSizeOfLargestEmptySubobject() const
Definition: RecordLayout.h:238
CharUnits getTypeAlignInChars(QualType T) const
Return the ABI-specified alignment of a (complete) type T, in characters.
CXXRecordDecl * getDefinition() const
Definition: DeclCXX.h:731
ObjCInterfaceDecl * getSuperClass() const
Definition: DeclObjC.cpp:314
SourceLocation Begin
const CXXRecordDecl * getPrimaryBase() const
getPrimaryBase - Get the primary base for this record.
Definition: RecordLayout.h:208
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:177
char __ovld __cnfn min(char x, char y)
Returns y if y < x, otherwise it returns x.
bool isTrivial() const
Determine whether this class is considered trivial.
Definition: DeclCXX.h:1470
bool isPolymorphic() const
Whether this class is polymorphic (C++ [class.virtual]), which means that the class contains or inher...
Definition: DeclCXX.h:1289
bool hasExtendableVFPtr() const
hasVFPtr - Does this class have a virtual function table pointer that can be extended by a derived cl...
Definition: RecordLayout.h:258
unsigned getMaxAlignment() const
getMaxAlignment - return the maximum alignment specified by attributes on this decl, 0 if there are none.
Definition: DeclBase.cpp:373
method_iterator method_end() const
Method past-the-end iterator.
Definition: DeclCXX.h:826
CharUnits getVBPtrOffset() const
getVBPtrOffset - Get the offset for virtual base table pointer.
Definition: RecordLayout.h:296
const Type * getBaseElementTypeUnsafe() const
Get the base element type of this type, potentially discarding type qualifiers.
Definition: Type.h:6063
CharUnits getRequiredAlignment() const
Definition: RecordLayout.h:281
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:1309
The result type of a method or function.
This template specialization was implicitly instantiated from a template.
Definition: Specifiers.h:149
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:681
decl_type * getFirstDecl()
Return the first declaration of this declaration or itself if this is the only declaration.
Definition: Redeclarable.h:220
static bool recordUsesEBO(const RecordDecl *RD)
RecordDecl * getDecl() const
Definition: Type.h:3854
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:181
static uint64_t roundUpSizeToCharAlignment(uint64_t Size, const ASTContext &Context)
#define false
Definition: stdbool.h:33
The "struct" keyword.
Definition: Type.h:4550
Only allocate objects in the tail padding of a base class if the base class is not POD according to t...
Definition: TargetCXXABI.h:313
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:1964
const ConstantArrayType * getAsConstantArrayType(QualType T) const
Definition: ASTContext.h:2272
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:1885
This template specialization was instantiated from a template due to an explicit instantiation defini...
Definition: Specifiers.h:161
CharUnits getDataSize() const
getDataSize() - Get the record data size, which is the record size without tail padding, in characters.
Definition: RecordLayout.h:187
bool useBitFieldTypeAlignment() const
Check whether the alignment of bit-field types is respected when laying out structures.
Definition: TargetInfo.h:507
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:3535
ASTContext & operator=(const ASTContext &)=delete
std::pair< CharUnits, CharUnits > getTypeInfoInChars(const Type *T) const
CanQualType UnsignedShortTy
Definition: ASTContext.h:974
ObjCIvarDecl * getNextIvar()
Definition: DeclObjC.h:1899
CharUnits getNonVirtualAlignment() const
getNonVirtualSize - Get the non-virtual alignment (in chars) of an object, which is the alignment of ...
Definition: RecordLayout.h:201
TagTypeKind
The kind of a tag type.
Definition: Type.h:4548
const ObjCInterfaceDecl * getClassInterface() const
Definition: DeclObjC.h:2341
Dataflow Directional Tag Classes.
CharUnits getSize() const
getSize - Get the record size in characters.
Definition: RecordLayout.h:174
method_iterator begin_overridden_methods() const
Definition: DeclCXX.cpp:1912
IndirectFieldDecl - An instance of this class is created to represent a field injected from an anonym...
Definition: Decl.h:2705
CanQualType UnsignedLongLongTy
Definition: ASTContext.h:975
ObjCInterfaceDecl * getDefinition()
Retrieve the definition of this class, or NULL if this class has been forward-declared (with @class) ...
Definition: DeclObjC.h:1471
This template specialization was instantiated from a template due to an explicit instantiation declar...
Definition: Specifiers.h:157
bool hasUserDeclaredConstructor() const
Determine whether this class has any user-declared constructors.
Definition: DeclCXX.h:936
TailPaddingUseRules getTailPaddingUseRules() const
Definition: TargetCXXABI.h:315
const CXXRecordDecl * getParent() const
Returns the parent of this method declaration, which is the class in which this method is defined...
Definition: DeclCXX.h:2085
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:1741
TemplateSpecializationKind
Describes the kind of template specialization that a particular template specialization declaration r...
Definition: Specifiers.h:143
ExternalASTSource * getExternalSource() const
Retrieve a pointer to the external AST source associated with this AST context, if any...
Definition: ASTContext.h:1017
T * get(ExternalASTSource *Source) const
Retrieve the pointer to the AST node that this lazy pointer.
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:1596
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:2448
bool isIncompleteArrayType() const
Definition: Type.h:5817
A helper class that allows the use of isa/cast/dyncast to detect TagType objects of structs/unions/cl...
Definition: Type.h:3845
CanQualType UnsignedLongTy
Definition: ASTContext.h:974
static bool RequiresVtordisp(const llvm::SmallPtrSetImpl< const CXXRecordDecl *> &BasesWithOverriddenMethods, const CXXRecordDecl *RD)
T * getAttr() const
Definition: DeclBase.h:531
uint64_t getCharWidth() const
Return the size of the character type, in bits.
Definition: ASTContext.h:1965
void setNonKeyFunction(const CXXMethodDecl *method)
Observe that the given method cannot be a key function.
Base for LValueReferenceType and RValueReferenceType.
Definition: Type.h:2364
The "class" keyword.
Definition: Type.h:4556
Represents a base class of a C++ class.
Definition: DeclCXX.h:191
char __ovld __cnfn max(char x, char y)
Returns y if x < y, otherwise it returns x.
uint64_t getTypeSize(QualType T) const
Return the size of the specified (complete) type T, in bits.
Definition: ASTContext.h:1961
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 NULL if there isn&#39;t one...
Represents a C++ struct/union/class.
Definition: DeclCXX.h:299
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:1866
CharUnits getNonVirtualSize() const
getNonVirtualSize - Get the non-virtual size (in chars) of an object, which is the size of the object...
Definition: RecordLayout.h:193
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:2088
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:304
llvm::DenseMap< const CXXRecordDecl *, VBaseInfo > VBaseOffsetsMapTy
Definition: RecordLayout.h:60
uint64_t getPointerAlign(unsigned AddrSpace) const
Definition: TargetInfo.h:314
Defines the clang::TargetInfo interface.
bool isMicrosoft() const
Is this ABI an MSVC-compatible ABI?
Definition: TargetCXXABI.h:154
StringRef getName() const
getName - Get the name of identifier for this declaration as a StringRef.
Definition: Decl.h:270
static void PrintBitFieldOffset(raw_ostream &OS, CharUnits Offset, unsigned Begin, unsigned Width, unsigned IndentLevel)
uint64_t Width
Definition: ASTContext.h:117
bool isUnion() const
Definition: Decl.h:3159
CharUnits getTypeSizeInChars(QualType T) const
Return the size of the specified (complete) type T, in characters.
QualType getType() const
Definition: Decl.h:639
NamedDecl - This represents a decl with a name.
Definition: Decl.h:245
ObjCIvarDecl * all_declared_ivar_begin()
all_declared_ivar_begin - return first ivar declared in this class, its extensions and its implementa...
Definition: DeclObjC.cpp:1543
bool hasOwnVBPtr() const
hasOwnVBPtr - Does this class provide its own virtual-base table pointer, rather than inheriting one ...
Definition: RecordLayout.h:270
unsigned getTargetAddressSpace(QualType T) const
Definition: ASTContext.h:2358
const LangOptions & getLangOpts() const
Definition: ASTContext.h:661
Represents the canonical version of C arrays with a specified constant size.
Definition: Type.h:2557
base_class_range vbases()
Definition: DeclCXX.h:790
SourceLocation getLocation() const
Definition: DeclBase.h:416
bool isExternallyVisible() const
Definition: Decl.h:371
CanQualType UnsignedIntTy
Definition: ASTContext.h:974
bool leadsWithZeroSizedBase() const
Definition: RecordLayout.h:289
method_range methods() const
Definition: DeclCXX.h:815