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  llvm::DenseMap<const CXXRecordDecl *, CharUnits>::iterator Known;
1173  if (Base->IsVirtual)
1174  HasExternalLayout = External.getExternalNVBaseOffset(Base->Class, Offset);
1175  else
1176  HasExternalLayout = External.getExternalVBaseOffset(Base->Class, Offset);
1177  }
1178 
1179  CharUnits UnpackedBaseAlign = Layout.getNonVirtualAlignment();
1180  CharUnits BaseAlign = (Packed) ? CharUnits::One() : UnpackedBaseAlign;
1181 
1182  // If we have an empty base class, try to place it at offset 0.
1183  if (Base->Class->isEmpty() &&
1184  (!HasExternalLayout || Offset == CharUnits::Zero()) &&
1185  EmptySubobjects->CanPlaceBaseAtOffset(Base, CharUnits::Zero())) {
1186  setSize(std::max(getSize(), Layout.getSize()));
1187  UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1188 
1189  return CharUnits::Zero();
1190  }
1191 
1192  // The maximum field alignment overrides base align.
1193  if (!MaxFieldAlignment.isZero()) {
1194  BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
1195  UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
1196  }
1197 
1198  if (!HasExternalLayout) {
1199  // Round up the current record size to the base's alignment boundary.
1200  Offset = getDataSize().alignTo(BaseAlign);
1201 
1202  // Try to place the base.
1203  while (!EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset))
1204  Offset += BaseAlign;
1205  } else {
1206  bool Allowed = EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset);
1207  (void)Allowed;
1208  assert(Allowed && "Base subobject externally placed at overlapping offset");
1209 
1210  if (InferAlignment && Offset < getDataSize().alignTo(BaseAlign)) {
1211  // The externally-supplied base offset is before the base offset we
1212  // computed. Assume that the structure is packed.
1213  Alignment = CharUnits::One();
1214  InferAlignment = false;
1215  }
1216  }
1217 
1218  if (!Base->Class->isEmpty()) {
1219  // Update the data size.
1220  setDataSize(Offset + Layout.getNonVirtualSize());
1221 
1222  setSize(std::max(getSize(), getDataSize()));
1223  } else
1224  setSize(std::max(getSize(), Offset + Layout.getSize()));
1225 
1226  // Remember max struct/class alignment.
1227  UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1228 
1229  return Offset;
1230 }
1231 
1232 void ItaniumRecordLayoutBuilder::InitializeLayout(const Decl *D) {
1233  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
1234  IsUnion = RD->isUnion();
1235  IsMsStruct = RD->isMsStruct(Context);
1236  }
1237 
1238  Packed = D->hasAttr<PackedAttr>();
1239 
1240  // Honor the default struct packing maximum alignment flag.
1241  if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct) {
1242  MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
1243  }
1244 
1245  // mac68k alignment supersedes maximum field alignment and attribute aligned,
1246  // and forces all structures to have 2-byte alignment. The IBM docs on it
1247  // allude to additional (more complicated) semantics, especially with regard
1248  // to bit-fields, but gcc appears not to follow that.
1249  if (D->hasAttr<AlignMac68kAttr>()) {
1250  IsMac68kAlign = true;
1251  MaxFieldAlignment = CharUnits::fromQuantity(2);
1252  Alignment = CharUnits::fromQuantity(2);
1253  } else {
1254  if (const MaxFieldAlignmentAttr *MFAA = D->getAttr<MaxFieldAlignmentAttr>())
1255  MaxFieldAlignment = Context.toCharUnitsFromBits(MFAA->getAlignment());
1256 
1257  if (unsigned MaxAlign = D->getMaxAlignment())
1258  UpdateAlignment(Context.toCharUnitsFromBits(MaxAlign));
1259  }
1260 
1261  // If there is an external AST source, ask it for the various offsets.
1262  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D))
1263  if (ExternalASTSource *Source = Context.getExternalSource()) {
1264  UseExternalLayout = Source->layoutRecordType(
1265  RD, External.Size, External.Align, External.FieldOffsets,
1266  External.BaseOffsets, External.VirtualBaseOffsets);
1267 
1268  // Update based on external alignment.
1269  if (UseExternalLayout) {
1270  if (External.Align > 0) {
1271  Alignment = Context.toCharUnitsFromBits(External.Align);
1272  } else {
1273  // The external source didn't have alignment information; infer it.
1274  InferAlignment = true;
1275  }
1276  }
1277  }
1278 }
1279 
1280 void ItaniumRecordLayoutBuilder::Layout(const RecordDecl *D) {
1281  InitializeLayout(D);
1282  LayoutFields(D);
1283 
1284  // Finally, round the size of the total struct up to the alignment of the
1285  // struct itself.
1286  FinishLayout(D);
1287 }
1288 
1289 void ItaniumRecordLayoutBuilder::Layout(const CXXRecordDecl *RD) {
1290  InitializeLayout(RD);
1291 
1292  // Lay out the vtable and the non-virtual bases.
1293  LayoutNonVirtualBases(RD);
1294 
1295  LayoutFields(RD);
1296 
1297  NonVirtualSize = Context.toCharUnitsFromBits(
1298  llvm::alignTo(getSizeInBits(), Context.getTargetInfo().getCharAlign()));
1299  NonVirtualAlignment = Alignment;
1300 
1301  // Lay out the virtual bases and add the primary virtual base offsets.
1302  LayoutVirtualBases(RD, RD);
1303 
1304  // Finally, round the size of the total struct up to the alignment
1305  // of the struct itself.
1306  FinishLayout(RD);
1307 
1308 #ifndef NDEBUG
1309  // Check that we have base offsets for all bases.
1310  for (const CXXBaseSpecifier &Base : RD->bases()) {
1311  if (Base.isVirtual())
1312  continue;
1313 
1314  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1315 
1316  assert(Bases.count(BaseDecl) && "Did not find base offset!");
1317  }
1318 
1319  // And all virtual bases.
1320  for (const CXXBaseSpecifier &Base : RD->vbases()) {
1321  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1322 
1323  assert(VBases.count(BaseDecl) && "Did not find base offset!");
1324  }
1325 #endif
1326 }
1327 
1328 void ItaniumRecordLayoutBuilder::Layout(const ObjCInterfaceDecl *D) {
1329  if (ObjCInterfaceDecl *SD = D->getSuperClass()) {
1330  const ASTRecordLayout &SL = Context.getASTObjCInterfaceLayout(SD);
1331 
1332  UpdateAlignment(SL.getAlignment());
1333 
1334  // We start laying out ivars not at the end of the superclass
1335  // structure, but at the next byte following the last field.
1336  setSize(SL.getDataSize());
1337  setDataSize(getSize());
1338  }
1339 
1340  InitializeLayout(D);
1341  // Layout each ivar sequentially.
1342  for (const ObjCIvarDecl *IVD = D->all_declared_ivar_begin(); IVD;
1343  IVD = IVD->getNextIvar())
1344  LayoutField(IVD, false);
1345 
1346  // Finally, round the size of the total struct up to the alignment of the
1347  // struct itself.
1348  FinishLayout(D);
1349 }
1350 
1351 void ItaniumRecordLayoutBuilder::LayoutFields(const RecordDecl *D) {
1352  // Layout each field, for now, just sequentially, respecting alignment. In
1353  // the future, this will need to be tweakable by targets.
1354  bool InsertExtraPadding = D->mayInsertExtraPadding(/*EmitRemark=*/true);
1355  bool HasFlexibleArrayMember = D->hasFlexibleArrayMember();
1356  for (auto I = D->field_begin(), End = D->field_end(); I != End; ++I) {
1357  auto Next(I);
1358  ++Next;
1359  LayoutField(*I,
1360  InsertExtraPadding && (Next != End || !HasFlexibleArrayMember));
1361  }
1362 }
1363 
1364 // Rounds the specified size to have it a multiple of the char size.
1365 static uint64_t
1367  const ASTContext &Context) {
1368  uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
1369  return llvm::alignTo(Size, CharAlignment);
1370 }
1371 
1372 void ItaniumRecordLayoutBuilder::LayoutWideBitField(uint64_t FieldSize,
1373  uint64_t TypeSize,
1374  bool FieldPacked,
1375  const FieldDecl *D) {
1376  assert(Context.getLangOpts().CPlusPlus &&
1377  "Can only have wide bit-fields in C++!");
1378 
1379  // Itanium C++ ABI 2.4:
1380  // If sizeof(T)*8 < n, let T' be the largest integral POD type with
1381  // sizeof(T')*8 <= n.
1382 
1383  QualType IntegralPODTypes[] = {
1384  Context.UnsignedCharTy, Context.UnsignedShortTy, Context.UnsignedIntTy,
1385  Context.UnsignedLongTy, Context.UnsignedLongLongTy
1386  };
1387 
1388  QualType Type;
1389  for (const QualType &QT : IntegralPODTypes) {
1390  uint64_t Size = Context.getTypeSize(QT);
1391 
1392  if (Size > FieldSize)
1393  break;
1394 
1395  Type = QT;
1396  }
1397  assert(!Type.isNull() && "Did not find a type!");
1398 
1399  CharUnits TypeAlign = Context.getTypeAlignInChars(Type);
1400 
1401  // We're not going to use any of the unfilled bits in the last byte.
1402  UnfilledBitsInLastUnit = 0;
1403  LastBitfieldTypeSize = 0;
1404 
1405  uint64_t FieldOffset;
1406  uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
1407 
1408  if (IsUnion) {
1409  uint64_t RoundedFieldSize = roundUpSizeToCharAlignment(FieldSize,
1410  Context);
1411  setDataSize(std::max(getDataSizeInBits(), RoundedFieldSize));
1412  FieldOffset = 0;
1413  } else {
1414  // The bitfield is allocated starting at the next offset aligned
1415  // appropriately for T', with length n bits.
1416  FieldOffset = llvm::alignTo(getDataSizeInBits(), Context.toBits(TypeAlign));
1417 
1418  uint64_t NewSizeInBits = FieldOffset + FieldSize;
1419 
1420  setDataSize(
1421  llvm::alignTo(NewSizeInBits, Context.getTargetInfo().getCharAlign()));
1422  UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;
1423  }
1424 
1425  // Place this field at the current location.
1426  FieldOffsets.push_back(FieldOffset);
1427 
1428  CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, FieldOffset,
1429  Context.toBits(TypeAlign), FieldPacked, D);
1430 
1431  // Update the size.
1432  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1433 
1434  // Remember max struct/class alignment.
1435  UpdateAlignment(TypeAlign);
1436 }
1437 
1438 void ItaniumRecordLayoutBuilder::LayoutBitField(const FieldDecl *D) {
1439  bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
1440  uint64_t FieldSize = D->getBitWidthValue(Context);
1441  TypeInfo FieldInfo = Context.getTypeInfo(D->getType());
1442  uint64_t TypeSize = FieldInfo.Width;
1443  unsigned FieldAlign = FieldInfo.Align;
1444 
1445  // UnfilledBitsInLastUnit is the difference between the end of the
1446  // last allocated bitfield (i.e. the first bit offset available for
1447  // bitfields) and the end of the current data size in bits (i.e. the
1448  // first bit offset available for non-bitfields). The current data
1449  // size in bits is always a multiple of the char size; additionally,
1450  // for ms_struct records it's also a multiple of the
1451  // LastBitfieldTypeSize (if set).
1452 
1453  // The struct-layout algorithm is dictated by the platform ABI,
1454  // which in principle could use almost any rules it likes. In
1455  // practice, UNIXy targets tend to inherit the algorithm described
1456  // in the System V generic ABI. The basic bitfield layout rule in
1457  // System V is to place bitfields at the next available bit offset
1458  // where the entire bitfield would fit in an aligned storage unit of
1459  // the declared type; it's okay if an earlier or later non-bitfield
1460  // is allocated in the same storage unit. However, some targets
1461  // (those that !useBitFieldTypeAlignment(), e.g. ARM APCS) don't
1462  // require this storage unit to be aligned, and therefore always put
1463  // the bitfield at the next available bit offset.
1464 
1465  // ms_struct basically requests a complete replacement of the
1466  // platform ABI's struct-layout algorithm, with the high-level goal
1467  // of duplicating MSVC's layout. For non-bitfields, this follows
1468  // the standard algorithm. The basic bitfield layout rule is to
1469  // allocate an entire unit of the bitfield's declared type
1470  // (e.g. 'unsigned long'), then parcel it up among successive
1471  // bitfields whose declared types have the same size, making a new
1472  // unit as soon as the last can no longer store the whole value.
1473  // Since it completely replaces the platform ABI's algorithm,
1474  // settings like !useBitFieldTypeAlignment() do not apply.
1475 
1476  // A zero-width bitfield forces the use of a new storage unit for
1477  // later bitfields. In general, this occurs by rounding up the
1478  // current size of the struct as if the algorithm were about to
1479  // place a non-bitfield of the field's formal type. Usually this
1480  // does not change the alignment of the struct itself, but it does
1481  // on some targets (those that useZeroLengthBitfieldAlignment(),
1482  // e.g. ARM). In ms_struct layout, zero-width bitfields are
1483  // ignored unless they follow a non-zero-width bitfield.
1484 
1485  // A field alignment restriction (e.g. from #pragma pack) or
1486  // specification (e.g. from __attribute__((aligned))) changes the
1487  // formal alignment of the field. For System V, this alters the
1488  // required alignment of the notional storage unit that must contain
1489  // the bitfield. For ms_struct, this only affects the placement of
1490  // new storage units. In both cases, the effect of #pragma pack is
1491  // ignored on zero-width bitfields.
1492 
1493  // On System V, a packed field (e.g. from #pragma pack or
1494  // __attribute__((packed))) always uses the next available bit
1495  // offset.
1496 
1497  // In an ms_struct struct, the alignment of a fundamental type is
1498  // always equal to its size. This is necessary in order to mimic
1499  // the i386 alignment rules on targets which might not fully align
1500  // all types (e.g. Darwin PPC32, where alignof(long long) == 4).
1501 
1502  // First, some simple bookkeeping to perform for ms_struct structs.
1503  if (IsMsStruct) {
1504  // The field alignment for integer types is always the size.
1505  FieldAlign = TypeSize;
1506 
1507  // If the previous field was not a bitfield, or was a bitfield
1508  // with a different storage unit size, we're done with that
1509  // storage unit.
1510  if (LastBitfieldTypeSize != TypeSize) {
1511  // Also, ignore zero-length bitfields after non-bitfields.
1512  if (!LastBitfieldTypeSize && !FieldSize)
1513  FieldAlign = 1;
1514 
1515  UnfilledBitsInLastUnit = 0;
1516  LastBitfieldTypeSize = 0;
1517  }
1518  }
1519 
1520  // If the field is wider than its declared type, it follows
1521  // different rules in all cases.
1522  if (FieldSize > TypeSize) {
1523  LayoutWideBitField(FieldSize, TypeSize, FieldPacked, D);
1524  return;
1525  }
1526 
1527  // Compute the next available bit offset.
1528  uint64_t FieldOffset =
1529  IsUnion ? 0 : (getDataSizeInBits() - UnfilledBitsInLastUnit);
1530 
1531  // Handle targets that don't honor bitfield type alignment.
1532  if (!IsMsStruct && !Context.getTargetInfo().useBitFieldTypeAlignment()) {
1533  // Some such targets do honor it on zero-width bitfields.
1534  if (FieldSize == 0 &&
1536  // The alignment to round up to is the max of the field's natural
1537  // alignment and a target-specific fixed value (sometimes zero).
1538  unsigned ZeroLengthBitfieldBoundary =
1540  FieldAlign = std::max(FieldAlign, ZeroLengthBitfieldBoundary);
1541 
1542  // If that doesn't apply, just ignore the field alignment.
1543  } else {
1544  FieldAlign = 1;
1545  }
1546  }
1547 
1548  // Remember the alignment we would have used if the field were not packed.
1549  unsigned UnpackedFieldAlign = FieldAlign;
1550 
1551  // Ignore the field alignment if the field is packed unless it has zero-size.
1552  if (!IsMsStruct && FieldPacked && FieldSize != 0)
1553  FieldAlign = 1;
1554 
1555  // But, if there's an 'aligned' attribute on the field, honor that.
1556  unsigned ExplicitFieldAlign = D->getMaxAlignment();
1557  if (ExplicitFieldAlign) {
1558  FieldAlign = std::max(FieldAlign, ExplicitFieldAlign);
1559  UnpackedFieldAlign = std::max(UnpackedFieldAlign, ExplicitFieldAlign);
1560  }
1561 
1562  // But, if there's a #pragma pack in play, that takes precedent over
1563  // even the 'aligned' attribute, for non-zero-width bitfields.
1564  unsigned MaxFieldAlignmentInBits = Context.toBits(MaxFieldAlignment);
1565  if (!MaxFieldAlignment.isZero() && FieldSize) {
1566  UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignmentInBits);
1567  if (FieldPacked)
1568  FieldAlign = UnpackedFieldAlign;
1569  else
1570  FieldAlign = std::min(FieldAlign, MaxFieldAlignmentInBits);
1571  }
1572 
1573  // But, ms_struct just ignores all of that in unions, even explicit
1574  // alignment attributes.
1575  if (IsMsStruct && IsUnion) {
1576  FieldAlign = UnpackedFieldAlign = 1;
1577  }
1578 
1579  // For purposes of diagnostics, we're going to simultaneously
1580  // compute the field offsets that we would have used if we weren't
1581  // adding any alignment padding or if the field weren't packed.
1582  uint64_t UnpaddedFieldOffset = FieldOffset;
1583  uint64_t UnpackedFieldOffset = FieldOffset;
1584 
1585  // Check if we need to add padding to fit the bitfield within an
1586  // allocation unit with the right size and alignment. The rules are
1587  // somewhat different here for ms_struct structs.
1588  if (IsMsStruct) {
1589  // If it's not a zero-width bitfield, and we can fit the bitfield
1590  // into the active storage unit (and we haven't already decided to
1591  // start a new storage unit), just do so, regardless of any other
1592  // other consideration. Otherwise, round up to the right alignment.
1593  if (FieldSize == 0 || FieldSize > UnfilledBitsInLastUnit) {
1594  FieldOffset = llvm::alignTo(FieldOffset, FieldAlign);
1595  UnpackedFieldOffset =
1596  llvm::alignTo(UnpackedFieldOffset, UnpackedFieldAlign);
1597  UnfilledBitsInLastUnit = 0;
1598  }
1599 
1600  } else {
1601  // #pragma pack, with any value, suppresses the insertion of padding.
1602  bool AllowPadding = MaxFieldAlignment.isZero();
1603 
1604  // Compute the real offset.
1605  if (FieldSize == 0 ||
1606  (AllowPadding &&
1607  (FieldOffset & (FieldAlign-1)) + FieldSize > TypeSize)) {
1608  FieldOffset = llvm::alignTo(FieldOffset, FieldAlign);
1609  } else if (ExplicitFieldAlign &&
1610  (MaxFieldAlignmentInBits == 0 ||
1611  ExplicitFieldAlign <= MaxFieldAlignmentInBits) &&
1613  // TODO: figure it out what needs to be done on targets that don't honor
1614  // bit-field type alignment like ARM APCS ABI.
1615  FieldOffset = llvm::alignTo(FieldOffset, ExplicitFieldAlign);
1616  }
1617 
1618  // Repeat the computation for diagnostic purposes.
1619  if (FieldSize == 0 ||
1620  (AllowPadding &&
1621  (UnpackedFieldOffset & (UnpackedFieldAlign-1)) + FieldSize > TypeSize))
1622  UnpackedFieldOffset =
1623  llvm::alignTo(UnpackedFieldOffset, UnpackedFieldAlign);
1624  else if (ExplicitFieldAlign &&
1625  (MaxFieldAlignmentInBits == 0 ||
1626  ExplicitFieldAlign <= MaxFieldAlignmentInBits) &&
1628  UnpackedFieldOffset =
1629  llvm::alignTo(UnpackedFieldOffset, ExplicitFieldAlign);
1630  }
1631 
1632  // If we're using external layout, give the external layout a chance
1633  // to override this information.
1634  if (UseExternalLayout)
1635  FieldOffset = updateExternalFieldOffset(D, FieldOffset);
1636 
1637  // Okay, place the bitfield at the calculated offset.
1638  FieldOffsets.push_back(FieldOffset);
1639 
1640  // Bookkeeping:
1641 
1642  // Anonymous members don't affect the overall record alignment,
1643  // except on targets where they do.
1644  if (!IsMsStruct &&
1646  !D->getIdentifier())
1647  FieldAlign = UnpackedFieldAlign = 1;
1648 
1649  // Diagnose differences in layout due to padding or packing.
1650  if (!UseExternalLayout)
1651  CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, UnpackedFieldOffset,
1652  UnpackedFieldAlign, FieldPacked, D);
1653 
1654  // Update DataSize to include the last byte containing (part of) the bitfield.
1655 
1656  // For unions, this is just a max operation, as usual.
1657  if (IsUnion) {
1658  // For ms_struct, allocate the entire storage unit --- unless this
1659  // is a zero-width bitfield, in which case just use a size of 1.
1660  uint64_t RoundedFieldSize;
1661  if (IsMsStruct) {
1662  RoundedFieldSize =
1663  (FieldSize ? TypeSize : Context.getTargetInfo().getCharWidth());
1664 
1665  // Otherwise, allocate just the number of bytes required to store
1666  // the bitfield.
1667  } else {
1668  RoundedFieldSize = roundUpSizeToCharAlignment(FieldSize, Context);
1669  }
1670  setDataSize(std::max(getDataSizeInBits(), RoundedFieldSize));
1671 
1672  // For non-zero-width bitfields in ms_struct structs, allocate a new
1673  // storage unit if necessary.
1674  } else if (IsMsStruct && FieldSize) {
1675  // We should have cleared UnfilledBitsInLastUnit in every case
1676  // where we changed storage units.
1677  if (!UnfilledBitsInLastUnit) {
1678  setDataSize(FieldOffset + TypeSize);
1679  UnfilledBitsInLastUnit = TypeSize;
1680  }
1681  UnfilledBitsInLastUnit -= FieldSize;
1682  LastBitfieldTypeSize = TypeSize;
1683 
1684  // Otherwise, bump the data size up to include the bitfield,
1685  // including padding up to char alignment, and then remember how
1686  // bits we didn't use.
1687  } else {
1688  uint64_t NewSizeInBits = FieldOffset + FieldSize;
1689  uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
1690  setDataSize(llvm::alignTo(NewSizeInBits, CharAlignment));
1691  UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;
1692 
1693  // The only time we can get here for an ms_struct is if this is a
1694  // zero-width bitfield, which doesn't count as anything for the
1695  // purposes of unfilled bits.
1696  LastBitfieldTypeSize = 0;
1697  }
1698 
1699  // Update the size.
1700  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1701 
1702  // Remember max struct/class alignment.
1703  UpdateAlignment(Context.toCharUnitsFromBits(FieldAlign),
1704  Context.toCharUnitsFromBits(UnpackedFieldAlign));
1705 }
1706 
1707 void ItaniumRecordLayoutBuilder::LayoutField(const FieldDecl *D,
1708  bool InsertExtraPadding) {
1709  if (D->isBitField()) {
1710  LayoutBitField(D);
1711  return;
1712  }
1713 
1714  uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
1715 
1716  // Reset the unfilled bits.
1717  UnfilledBitsInLastUnit = 0;
1718  LastBitfieldTypeSize = 0;
1719 
1720  bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
1721  CharUnits FieldOffset =
1722  IsUnion ? CharUnits::Zero() : getDataSize();
1723  CharUnits FieldSize;
1724  CharUnits FieldAlign;
1725 
1726  if (D->getType()->isIncompleteArrayType()) {
1727  // This is a flexible array member; we can't directly
1728  // query getTypeInfo about these, so we figure it out here.
1729  // Flexible array members don't have any size, but they
1730  // have to be aligned appropriately for their element type.
1731  FieldSize = CharUnits::Zero();
1732  const ArrayType* ATy = Context.getAsArrayType(D->getType());
1733  FieldAlign = Context.getTypeAlignInChars(ATy->getElementType());
1734  } else if (const ReferenceType *RT = D->getType()->getAs<ReferenceType>()) {
1735  unsigned AS = RT->getPointeeType().getAddressSpace();
1736  FieldSize =
1737  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(AS));
1738  FieldAlign =
1739  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(AS));
1740  } else {
1741  std::pair<CharUnits, CharUnits> FieldInfo =
1742  Context.getTypeInfoInChars(D->getType());
1743  FieldSize = FieldInfo.first;
1744  FieldAlign = FieldInfo.second;
1745 
1746  if (IsMsStruct) {
1747  // If MS bitfield layout is required, figure out what type is being
1748  // laid out and align the field to the width of that type.
1749 
1750  // Resolve all typedefs down to their base type and round up the field
1751  // alignment if necessary.
1752  QualType T = Context.getBaseElementType(D->getType());
1753  if (const BuiltinType *BTy = T->getAs<BuiltinType>()) {
1754  CharUnits TypeSize = Context.getTypeSizeInChars(BTy);
1755  if (TypeSize > FieldAlign)
1756  FieldAlign = TypeSize;
1757  }
1758  }
1759  }
1760 
1761  // The align if the field is not packed. This is to check if the attribute
1762  // was unnecessary (-Wpacked).
1763  CharUnits UnpackedFieldAlign = FieldAlign;
1764  CharUnits UnpackedFieldOffset = FieldOffset;
1765 
1766  if (FieldPacked)
1767  FieldAlign = CharUnits::One();
1768  CharUnits MaxAlignmentInChars =
1769  Context.toCharUnitsFromBits(D->getMaxAlignment());
1770  FieldAlign = std::max(FieldAlign, MaxAlignmentInChars);
1771  UnpackedFieldAlign = std::max(UnpackedFieldAlign, MaxAlignmentInChars);
1772 
1773  // The maximum field alignment overrides the aligned attribute.
1774  if (!MaxFieldAlignment.isZero()) {
1775  FieldAlign = std::min(FieldAlign, MaxFieldAlignment);
1776  UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignment);
1777  }
1778 
1779  // Round up the current record size to the field's alignment boundary.
1780  FieldOffset = FieldOffset.alignTo(FieldAlign);
1781  UnpackedFieldOffset = UnpackedFieldOffset.alignTo(UnpackedFieldAlign);
1782 
1783  if (UseExternalLayout) {
1784  FieldOffset = Context.toCharUnitsFromBits(
1785  updateExternalFieldOffset(D, Context.toBits(FieldOffset)));
1786 
1787  if (!IsUnion && EmptySubobjects) {
1788  // Record the fact that we're placing a field at this offset.
1789  bool Allowed = EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset);
1790  (void)Allowed;
1791  assert(Allowed && "Externally-placed field cannot be placed here");
1792  }
1793  } else {
1794  if (!IsUnion && EmptySubobjects) {
1795  // Check if we can place the field at this offset.
1796  while (!EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset)) {
1797  // We couldn't place the field at the offset. Try again at a new offset.
1798  FieldOffset += FieldAlign;
1799  }
1800  }
1801  }
1802 
1803  // Place this field at the current location.
1804  FieldOffsets.push_back(Context.toBits(FieldOffset));
1805 
1806  if (!UseExternalLayout)
1807  CheckFieldPadding(Context.toBits(FieldOffset), UnpaddedFieldOffset,
1808  Context.toBits(UnpackedFieldOffset),
1809  Context.toBits(UnpackedFieldAlign), FieldPacked, D);
1810 
1811  if (InsertExtraPadding) {
1812  CharUnits ASanAlignment = CharUnits::fromQuantity(8);
1813  CharUnits ExtraSizeForAsan = ASanAlignment;
1814  if (FieldSize % ASanAlignment)
1815  ExtraSizeForAsan +=
1816  ASanAlignment - CharUnits::fromQuantity(FieldSize % ASanAlignment);
1817  FieldSize += ExtraSizeForAsan;
1818  }
1819 
1820  // Reserve space for this field.
1821  uint64_t FieldSizeInBits = Context.toBits(FieldSize);
1822  if (IsUnion)
1823  setDataSize(std::max(getDataSizeInBits(), FieldSizeInBits));
1824  else
1825  setDataSize(FieldOffset + FieldSize);
1826 
1827  // Update the size.
1828  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1829 
1830  // Remember max struct/class alignment.
1831  UpdateAlignment(FieldAlign, UnpackedFieldAlign);
1832 }
1833 
1834 void ItaniumRecordLayoutBuilder::FinishLayout(const NamedDecl *D) {
1835  // In C++, records cannot be of size 0.
1836  if (Context.getLangOpts().CPlusPlus && getSizeInBits() == 0) {
1837  if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) {
1838  // Compatibility with gcc requires a class (pod or non-pod)
1839  // which is not empty but of size 0; such as having fields of
1840  // array of zero-length, remains of Size 0
1841  if (RD->isEmpty())
1842  setSize(CharUnits::One());
1843  }
1844  else
1845  setSize(CharUnits::One());
1846  }
1847 
1848  // Finally, round the size of the record up to the alignment of the
1849  // record itself.
1850  uint64_t UnpaddedSize = getSizeInBits() - UnfilledBitsInLastUnit;
1851  uint64_t UnpackedSizeInBits =
1852  llvm::alignTo(getSizeInBits(), Context.toBits(UnpackedAlignment));
1853  uint64_t RoundedSize =
1854  llvm::alignTo(getSizeInBits(), Context.toBits(Alignment));
1855 
1856  if (UseExternalLayout) {
1857  // If we're inferring alignment, and the external size is smaller than
1858  // our size after we've rounded up to alignment, conservatively set the
1859  // alignment to 1.
1860  if (InferAlignment && External.Size < RoundedSize) {
1861  Alignment = CharUnits::One();
1862  InferAlignment = false;
1863  }
1864  setSize(External.Size);
1865  return;
1866  }
1867 
1868  // Set the size to the final size.
1869  setSize(RoundedSize);
1870 
1871  unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
1872  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
1873  // Warn if padding was introduced to the struct/class/union.
1874  if (getSizeInBits() > UnpaddedSize) {
1875  unsigned PadSize = getSizeInBits() - UnpaddedSize;
1876  bool InBits = true;
1877  if (PadSize % CharBitNum == 0) {
1878  PadSize = PadSize / CharBitNum;
1879  InBits = false;
1880  }
1881  Diag(RD->getLocation(), diag::warn_padded_struct_size)
1882  << Context.getTypeDeclType(RD)
1883  << PadSize
1884  << (InBits ? 1 : 0); // (byte|bit)
1885  }
1886 
1887  // Warn if we packed it unnecessarily, when the unpacked alignment is not
1888  // greater than the one after packing, the size in bits doesn't change and
1889  // the offset of each field is identical.
1890  if (Packed && UnpackedAlignment <= Alignment &&
1891  UnpackedSizeInBits == getSizeInBits() && !HasPackedField)
1892  Diag(D->getLocation(), diag::warn_unnecessary_packed)
1893  << Context.getTypeDeclType(RD);
1894  }
1895 }
1896 
1897 void ItaniumRecordLayoutBuilder::UpdateAlignment(
1898  CharUnits NewAlignment, CharUnits UnpackedNewAlignment) {
1899  // The alignment is not modified when using 'mac68k' alignment or when
1900  // we have an externally-supplied layout that also provides overall alignment.
1901  if (IsMac68kAlign || (UseExternalLayout && !InferAlignment))
1902  return;
1903 
1904  if (NewAlignment > Alignment) {
1905  assert(llvm::isPowerOf2_64(NewAlignment.getQuantity()) &&
1906  "Alignment not a power of 2");
1907  Alignment = NewAlignment;
1908  }
1909 
1910  if (UnpackedNewAlignment > UnpackedAlignment) {
1911  assert(llvm::isPowerOf2_64(UnpackedNewAlignment.getQuantity()) &&
1912  "Alignment not a power of 2");
1913  UnpackedAlignment = UnpackedNewAlignment;
1914  }
1915 }
1916 
1917 uint64_t
1918 ItaniumRecordLayoutBuilder::updateExternalFieldOffset(const FieldDecl *Field,
1919  uint64_t ComputedOffset) {
1920  uint64_t ExternalFieldOffset = External.getExternalFieldOffset(Field);
1921 
1922  if (InferAlignment && ExternalFieldOffset < ComputedOffset) {
1923  // The externally-supplied field offset is before the field offset we
1924  // computed. Assume that the structure is packed.
1925  Alignment = CharUnits::One();
1926  InferAlignment = false;
1927  }
1928 
1929  // Use the externally-supplied field offset.
1930  return ExternalFieldOffset;
1931 }
1932 
1933 /// \brief Get diagnostic %select index for tag kind for
1934 /// field padding diagnostic message.
1935 /// WARNING: Indexes apply to particular diagnostics only!
1936 ///
1937 /// \returns diagnostic %select index.
1939  switch (Tag) {
1940  case TTK_Struct: return 0;
1941  case TTK_Interface: return 1;
1942  case TTK_Class: return 2;
1943  default: llvm_unreachable("Invalid tag kind for field padding diagnostic!");
1944  }
1945 }
1946 
1947 void ItaniumRecordLayoutBuilder::CheckFieldPadding(
1948  uint64_t Offset, uint64_t UnpaddedOffset, uint64_t UnpackedOffset,
1949  unsigned UnpackedAlign, bool isPacked, const FieldDecl *D) {
1950  // We let objc ivars without warning, objc interfaces generally are not used
1951  // for padding tricks.
1952  if (isa<ObjCIvarDecl>(D))
1953  return;
1954 
1955  // Don't warn about structs created without a SourceLocation. This can
1956  // be done by clients of the AST, such as codegen.
1957  if (D->getLocation().isInvalid())
1958  return;
1959 
1960  unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
1961 
1962  // Warn if padding was introduced to the struct/class.
1963  if (!IsUnion && Offset > UnpaddedOffset) {
1964  unsigned PadSize = Offset - UnpaddedOffset;
1965  bool InBits = true;
1966  if (PadSize % CharBitNum == 0) {
1967  PadSize = PadSize / CharBitNum;
1968  InBits = false;
1969  }
1970  if (D->getIdentifier())
1971  Diag(D->getLocation(), diag::warn_padded_struct_field)
1973  << Context.getTypeDeclType(D->getParent())
1974  << PadSize
1975  << (InBits ? 1 : 0) // (byte|bit)
1976  << D->getIdentifier();
1977  else
1978  Diag(D->getLocation(), diag::warn_padded_struct_anon_field)
1980  << Context.getTypeDeclType(D->getParent())
1981  << PadSize
1982  << (InBits ? 1 : 0); // (byte|bit)
1983  }
1984  if (isPacked && Offset != UnpackedOffset) {
1985  HasPackedField = true;
1986  }
1987 }
1988 
1990  const CXXRecordDecl *RD) {
1991  // If a class isn't polymorphic it doesn't have a key function.
1992  if (!RD->isPolymorphic())
1993  return nullptr;
1994 
1995  // A class that is not externally visible doesn't have a key function. (Or
1996  // at least, there's no point to assigning a key function to such a class;
1997  // this doesn't affect the ABI.)
1998  if (!RD->isExternallyVisible())
1999  return nullptr;
2000 
2001  // Template instantiations don't have key functions per Itanium C++ ABI 5.2.6.
2002  // Same behavior as GCC.
2004  if (TSK == TSK_ImplicitInstantiation ||
2007  return nullptr;
2008 
2009  bool allowInlineFunctions =
2011 
2012  for (const CXXMethodDecl *MD : RD->methods()) {
2013  if (!MD->isVirtual())
2014  continue;
2015 
2016  if (MD->isPure())
2017  continue;
2018 
2019  // Ignore implicit member functions, they are always marked as inline, but
2020  // they don't have a body until they're defined.
2021  if (MD->isImplicit())
2022  continue;
2023 
2024  if (MD->isInlineSpecified())
2025  continue;
2026 
2027  if (MD->hasInlineBody())
2028  continue;
2029 
2030  // Ignore inline deleted or defaulted functions.
2031  if (!MD->isUserProvided())
2032  continue;
2033 
2034  // In certain ABIs, ignore functions with out-of-line inline definitions.
2035  if (!allowInlineFunctions) {
2036  const FunctionDecl *Def;
2037  if (MD->hasBody(Def) && Def->isInlineSpecified())
2038  continue;
2039  }
2040 
2041  if (Context.getLangOpts().CUDA) {
2042  // While compiler may see key method in this TU, during CUDA
2043  // compilation we should ignore methods that are not accessible
2044  // on this side of compilation.
2045  if (Context.getLangOpts().CUDAIsDevice) {
2046  // In device mode ignore methods without __device__ attribute.
2047  if (!MD->hasAttr<CUDADeviceAttr>())
2048  continue;
2049  } else {
2050  // In host mode ignore __device__-only methods.
2051  if (!MD->hasAttr<CUDAHostAttr>() && MD->hasAttr<CUDADeviceAttr>())
2052  continue;
2053  }
2054  }
2055 
2056  // If the key function is dllimport but the class isn't, then the class has
2057  // no key function. The DLL that exports the key function won't export the
2058  // vtable in this case.
2059  if (MD->hasAttr<DLLImportAttr>() && !RD->hasAttr<DLLImportAttr>())
2060  return nullptr;
2061 
2062  // We found it.
2063  return MD;
2064  }
2065 
2066  return nullptr;
2067 }
2068 
2070  unsigned DiagID) {
2071  return Context.getDiagnostics().Report(Loc, DiagID);
2072 }
2073 
2074 /// Does the target C++ ABI require us to skip over the tail-padding
2075 /// of the given class (considering it as a base class) when allocating
2076 /// objects?
2077 static bool mustSkipTailPadding(TargetCXXABI ABI, const CXXRecordDecl *RD) {
2078  switch (ABI.getTailPaddingUseRules()) {
2080  return false;
2081 
2083  // FIXME: To the extent that this is meant to cover the Itanium ABI
2084  // rules, we should implement the restrictions about over-sized
2085  // bitfields:
2086  //
2087  // http://itanium-cxx-abi.github.io/cxx-abi/abi.html#POD :
2088  // In general, a type is considered a POD for the purposes of
2089  // layout if it is a POD type (in the sense of ISO C++
2090  // [basic.types]). However, a POD-struct or POD-union (in the
2091  // sense of ISO C++ [class]) with a bitfield member whose
2092  // declared width is wider than the declared type of the
2093  // bitfield is not a POD for the purpose of layout. Similarly,
2094  // an array type is not a POD for the purpose of layout if the
2095  // element type of the array is not a POD for the purpose of
2096  // layout.
2097  //
2098  // Where references to the ISO C++ are made in this paragraph,
2099  // the Technical Corrigendum 1 version of the standard is
2100  // intended.
2101  return RD->isPOD();
2102 
2104  // This is equivalent to RD->getTypeForDecl().isCXX11PODType(),
2105  // but with a lot of abstraction penalty stripped off. This does
2106  // assume that these properties are set correctly even in C++98
2107  // mode; fortunately, that is true because we want to assign
2108  // consistently semantics to the type-traits intrinsics (or at
2109  // least as many of them as possible).
2110  return RD->isTrivial() && RD->isStandardLayout();
2111  }
2112 
2113  llvm_unreachable("bad tail-padding use kind");
2114 }
2115 
2116 static bool isMsLayout(const ASTContext &Context) {
2117  return Context.getTargetInfo().getCXXABI().isMicrosoft();
2118 }
2119 
2120 // This section contains an implementation of struct layout that is, up to the
2121 // included tests, compatible with cl.exe (2013). The layout produced is
2122 // significantly different than those produced by the Itanium ABI. Here we note
2123 // the most important differences.
2124 //
2125 // * The alignment of bitfields in unions is ignored when computing the
2126 // alignment of the union.
2127 // * The existence of zero-width bitfield that occurs after anything other than
2128 // a non-zero length bitfield is ignored.
2129 // * There is no explicit primary base for the purposes of layout. All bases
2130 // with vfptrs are laid out first, followed by all bases without vfptrs.
2131 // * The Itanium equivalent vtable pointers are split into a vfptr (virtual
2132 // function pointer) and a vbptr (virtual base pointer). They can each be
2133 // shared with a, non-virtual bases. These bases need not be the same. vfptrs
2134 // always occur at offset 0. vbptrs can occur at an arbitrary offset and are
2135 // placed after the lexicographically last non-virtual base. This placement
2136 // is always before fields but can be in the middle of the non-virtual bases
2137 // due to the two-pass layout scheme for non-virtual-bases.
2138 // * Virtual bases sometimes require a 'vtordisp' field that is laid out before
2139 // the virtual base and is used in conjunction with virtual overrides during
2140 // construction and destruction. This is always a 4 byte value and is used as
2141 // an alternative to constructor vtables.
2142 // * vtordisps are allocated in a block of memory with size and alignment equal
2143 // to the alignment of the completed structure (before applying __declspec(
2144 // align())). The vtordisp always occur at the end of the allocation block,
2145 // immediately prior to the virtual base.
2146 // * vfptrs are injected after all bases and fields have been laid out. In
2147 // order to guarantee proper alignment of all fields, the vfptr injection
2148 // pushes all bases and fields back by the alignment imposed by those bases
2149 // and fields. This can potentially add a significant amount of padding.
2150 // vfptrs are always injected at offset 0.
2151 // * vbptrs are injected after all bases and fields have been laid out. In
2152 // order to guarantee proper alignment of all fields, the vfptr injection
2153 // pushes all bases and fields back by the alignment imposed by those bases
2154 // and fields. This can potentially add a significant amount of padding.
2155 // vbptrs are injected immediately after the last non-virtual base as
2156 // lexicographically ordered in the code. If this site isn't pointer aligned
2157 // the vbptr is placed at the next properly aligned location. Enough padding
2158 // is added to guarantee a fit.
2159 // * The last zero sized non-virtual base can be placed at the end of the
2160 // struct (potentially aliasing another object), or may alias with the first
2161 // field, even if they are of the same type.
2162 // * The last zero size virtual base may be placed at the end of the struct
2163 // potentially aliasing another object.
2164 // * The ABI attempts to avoid aliasing of zero sized bases by adding padding
2165 // between bases or vbases with specific properties. The criteria for
2166 // additional padding between two bases is that the first base is zero sized
2167 // or ends with a zero sized subobject and the second base is zero sized or
2168 // trails with a zero sized base or field (sharing of vfptrs can reorder the
2169 // layout of the so the leading base is not always the first one declared).
2170 // This rule does take into account fields that are not records, so padding
2171 // will occur even if the last field is, e.g. an int. The padding added for
2172 // bases is 1 byte. The padding added between vbases depends on the alignment
2173 // of the object but is at least 4 bytes (in both 32 and 64 bit modes).
2174 // * There is no concept of non-virtual alignment, non-virtual alignment and
2175 // alignment are always identical.
2176 // * There is a distinction between alignment and required alignment.
2177 // __declspec(align) changes the required alignment of a struct. This
2178 // alignment is _always_ obeyed, even in the presence of #pragma pack. A
2179 // record inherits required alignment from all of its fields and bases.
2180 // * __declspec(align) on bitfields has the effect of changing the bitfield's
2181 // alignment instead of its required alignment. This is the only known way
2182 // to make the alignment of a struct bigger than 8. Interestingly enough
2183 // this alignment is also immune to the effects of #pragma pack and can be
2184 // used to create structures with large alignment under #pragma pack.
2185 // However, because it does not impact required alignment, such a structure,
2186 // when used as a field or base, will not be aligned if #pragma pack is
2187 // still active at the time of use.
2188 //
2189 // Known incompatibilities:
2190 // * all: #pragma pack between fields in a record
2191 // * 2010 and back: If the last field in a record is a bitfield, every object
2192 // laid out after the record will have extra padding inserted before it. The
2193 // extra padding will have size equal to the size of the storage class of the
2194 // bitfield. 0 sized bitfields don't exhibit this behavior and the extra
2195 // padding can be avoided by adding a 0 sized bitfield after the non-zero-
2196 // sized bitfield.
2197 // * 2012 and back: In 64-bit mode, if the alignment of a record is 16 or
2198 // greater due to __declspec(align()) then a second layout phase occurs after
2199 // The locations of the vf and vb pointers are known. This layout phase
2200 // suffers from the "last field is a bitfield" bug in 2010 and results in
2201 // _every_ field getting padding put in front of it, potentially including the
2202 // vfptr, leaving the vfprt at a non-zero location which results in a fault if
2203 // anything tries to read the vftbl. The second layout phase also treats
2204 // bitfields as separate entities and gives them each storage rather than
2205 // packing them. Additionally, because this phase appears to perform a
2206 // (an unstable) sort on the members before laying them out and because merged
2207 // bitfields have the same address, the bitfields end up in whatever order
2208 // the sort left them in, a behavior we could never hope to replicate.
2209 
2210 namespace {
2211 struct MicrosoftRecordLayoutBuilder {
2212  struct ElementInfo {
2213  CharUnits Size;
2214  CharUnits Alignment;
2215  };
2216  typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
2217  MicrosoftRecordLayoutBuilder(const ASTContext &Context) : Context(Context) {}
2218 private:
2219  MicrosoftRecordLayoutBuilder(const MicrosoftRecordLayoutBuilder &) = delete;
2220  void operator=(const MicrosoftRecordLayoutBuilder &) = delete;
2221 public:
2222  void layout(const RecordDecl *RD);
2223  void cxxLayout(const CXXRecordDecl *RD);
2224  /// \brief Initializes size and alignment and honors some flags.
2225  void initializeLayout(const RecordDecl *RD);
2226  /// \brief Initialized C++ layout, compute alignment and virtual alignment and
2227  /// existence of vfptrs and vbptrs. Alignment is needed before the vfptr is
2228  /// laid out.
2229  void initializeCXXLayout(const CXXRecordDecl *RD);
2230  void layoutNonVirtualBases(const CXXRecordDecl *RD);
2231  void layoutNonVirtualBase(const CXXRecordDecl *RD,
2232  const CXXRecordDecl *BaseDecl,
2233  const ASTRecordLayout &BaseLayout,
2234  const ASTRecordLayout *&PreviousBaseLayout);
2235  void injectVFPtr(const CXXRecordDecl *RD);
2236  void injectVBPtr(const CXXRecordDecl *RD);
2237  /// \brief Lays out the fields of the record. Also rounds size up to
2238  /// alignment.
2239  void layoutFields(const RecordDecl *RD);
2240  void layoutField(const FieldDecl *FD);
2241  void layoutBitField(const FieldDecl *FD);
2242  /// \brief Lays out a single zero-width bit-field in the record and handles
2243  /// special cases associated with zero-width bit-fields.
2244  void layoutZeroWidthBitField(const FieldDecl *FD);
2245  void layoutVirtualBases(const CXXRecordDecl *RD);
2246  void finalizeLayout(const RecordDecl *RD);
2247  /// \brief Gets the size and alignment of a base taking pragma pack and
2248  /// __declspec(align) into account.
2249  ElementInfo getAdjustedElementInfo(const ASTRecordLayout &Layout);
2250  /// \brief Gets the size and alignment of a field taking pragma pack and
2251  /// __declspec(align) into account. It also updates RequiredAlignment as a
2252  /// side effect because it is most convenient to do so here.
2253  ElementInfo getAdjustedElementInfo(const FieldDecl *FD);
2254  /// \brief Places a field at an offset in CharUnits.
2255  void placeFieldAtOffset(CharUnits FieldOffset) {
2256  FieldOffsets.push_back(Context.toBits(FieldOffset));
2257  }
2258  /// \brief Places a bitfield at a bit offset.
2259  void placeFieldAtBitOffset(uint64_t FieldOffset) {
2260  FieldOffsets.push_back(FieldOffset);
2261  }
2262  /// \brief Compute the set of virtual bases for which vtordisps are required.
2263  void computeVtorDispSet(
2264  llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtorDispSet,
2265  const CXXRecordDecl *RD) const;
2266  const ASTContext &Context;
2267  /// \brief The size of the record being laid out.
2268  CharUnits Size;
2269  /// \brief The non-virtual size of the record layout.
2270  CharUnits NonVirtualSize;
2271  /// \brief The data size of the record layout.
2272  CharUnits DataSize;
2273  /// \brief The current alignment of the record layout.
2274  CharUnits Alignment;
2275  /// \brief The maximum allowed field alignment. This is set by #pragma pack.
2276  CharUnits MaxFieldAlignment;
2277  /// \brief The alignment that this record must obey. This is imposed by
2278  /// __declspec(align()) on the record itself or one of its fields or bases.
2279  CharUnits RequiredAlignment;
2280  /// \brief The size of the allocation of the currently active bitfield.
2281  /// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield
2282  /// is true.
2283  CharUnits CurrentBitfieldSize;
2284  /// \brief Offset to the virtual base table pointer (if one exists).
2285  CharUnits VBPtrOffset;
2286  /// \brief Minimum record size possible.
2287  CharUnits MinEmptyStructSize;
2288  /// \brief The size and alignment info of a pointer.
2289  ElementInfo PointerInfo;
2290  /// \brief The primary base class (if one exists).
2291  const CXXRecordDecl *PrimaryBase;
2292  /// \brief The class we share our vb-pointer with.
2293  const CXXRecordDecl *SharedVBPtrBase;
2294  /// \brief The collection of field offsets.
2295  SmallVector<uint64_t, 16> FieldOffsets;
2296  /// \brief Base classes and their offsets in the record.
2297  BaseOffsetsMapTy Bases;
2298  /// \brief virtual base classes and their offsets in the record.
2300  /// \brief The number of remaining bits in our last bitfield allocation.
2301  /// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield is
2302  /// true.
2303  unsigned RemainingBitsInField;
2304  bool IsUnion : 1;
2305  /// \brief True if the last field laid out was a bitfield and was not 0
2306  /// width.
2307  bool LastFieldIsNonZeroWidthBitfield : 1;
2308  /// \brief True if the class has its own vftable pointer.
2309  bool HasOwnVFPtr : 1;
2310  /// \brief True if the class has a vbtable pointer.
2311  bool HasVBPtr : 1;
2312  /// \brief True if the last sub-object within the type is zero sized or the
2313  /// object itself is zero sized. This *does not* count members that are not
2314  /// records. Only used for MS-ABI.
2315  bool EndsWithZeroSizedObject : 1;
2316  /// \brief True if this class is zero sized or first base is zero sized or
2317  /// has this property. Only used for MS-ABI.
2318  bool LeadsWithZeroSizedBase : 1;
2319 
2320  /// \brief True if the external AST source provided a layout for this record.
2321  bool UseExternalLayout : 1;
2322 
2323  /// \brief The layout provided by the external AST source. Only active if
2324  /// UseExternalLayout is true.
2325  ExternalLayout External;
2326 };
2327 } // namespace
2328 
2329 MicrosoftRecordLayoutBuilder::ElementInfo
2330 MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
2331  const ASTRecordLayout &Layout) {
2332  ElementInfo Info;
2333  Info.Alignment = Layout.getAlignment();
2334  // Respect pragma pack.
2335  if (!MaxFieldAlignment.isZero())
2336  Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
2337  // Track zero-sized subobjects here where it's already available.
2338  EndsWithZeroSizedObject = Layout.endsWithZeroSizedObject();
2339  // Respect required alignment, this is necessary because we may have adjusted
2340  // the alignment in the case of pragam pack. Note that the required alignment
2341  // doesn't actually apply to the struct alignment at this point.
2342  Alignment = std::max(Alignment, Info.Alignment);
2343  RequiredAlignment = std::max(RequiredAlignment, Layout.getRequiredAlignment());
2344  Info.Alignment = std::max(Info.Alignment, Layout.getRequiredAlignment());
2345  Info.Size = Layout.getNonVirtualSize();
2346  return Info;
2347 }
2348 
2349 MicrosoftRecordLayoutBuilder::ElementInfo
2350 MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
2351  const FieldDecl *FD) {
2352  // Get the alignment of the field type's natural alignment, ignore any
2353  // alignment attributes.
2354  ElementInfo Info;
2355  std::tie(Info.Size, Info.Alignment) =
2357  // Respect align attributes on the field.
2358  CharUnits FieldRequiredAlignment =
2359  Context.toCharUnitsFromBits(FD->getMaxAlignment());
2360  // Respect align attributes on the type.
2361  if (Context.isAlignmentRequired(FD->getType()))
2362  FieldRequiredAlignment = std::max(
2363  Context.getTypeAlignInChars(FD->getType()), FieldRequiredAlignment);
2364  // Respect attributes applied to subobjects of the field.
2365  if (FD->isBitField())
2366  // For some reason __declspec align impacts alignment rather than required
2367  // alignment when it is applied to bitfields.
2368  Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
2369  else {
2370  if (auto RT =
2372  auto const &Layout = Context.getASTRecordLayout(RT->getDecl());
2373  EndsWithZeroSizedObject = Layout.endsWithZeroSizedObject();
2374  FieldRequiredAlignment = std::max(FieldRequiredAlignment,
2375  Layout.getRequiredAlignment());
2376  }
2377  // Capture required alignment as a side-effect.
2378  RequiredAlignment = std::max(RequiredAlignment, FieldRequiredAlignment);
2379  }
2380  // Respect pragma pack, attribute pack and declspec align
2381  if (!MaxFieldAlignment.isZero())
2382  Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
2383  if (FD->hasAttr<PackedAttr>())
2384  Info.Alignment = CharUnits::One();
2385  Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
2386  return Info;
2387 }
2388 
2389 void MicrosoftRecordLayoutBuilder::layout(const RecordDecl *RD) {
2390  // For C record layout, zero-sized records always have size 4.
2391  MinEmptyStructSize = CharUnits::fromQuantity(4);
2392  initializeLayout(RD);
2393  layoutFields(RD);
2394  DataSize = Size = Size.alignTo(Alignment);
2395  RequiredAlignment = std::max(
2396  RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
2397  finalizeLayout(RD);
2398 }
2399 
2400 void MicrosoftRecordLayoutBuilder::cxxLayout(const CXXRecordDecl *RD) {
2401  // The C++ standard says that empty structs have size 1.
2402  MinEmptyStructSize = CharUnits::One();
2403  initializeLayout(RD);
2404  initializeCXXLayout(RD);
2405  layoutNonVirtualBases(RD);
2406  layoutFields(RD);
2407  injectVBPtr(RD);
2408  injectVFPtr(RD);
2409  if (HasOwnVFPtr || (HasVBPtr && !SharedVBPtrBase))
2410  Alignment = std::max(Alignment, PointerInfo.Alignment);
2411  auto RoundingAlignment = Alignment;
2412  if (!MaxFieldAlignment.isZero())
2413  RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
2414  NonVirtualSize = Size = Size.alignTo(RoundingAlignment);
2415  RequiredAlignment = std::max(
2416  RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
2417  layoutVirtualBases(RD);
2418  finalizeLayout(RD);
2419 }
2420 
2421 void MicrosoftRecordLayoutBuilder::initializeLayout(const RecordDecl *RD) {
2422  IsUnion = RD->isUnion();
2423  Size = CharUnits::Zero();
2424  Alignment = CharUnits::One();
2425  // In 64-bit mode we always perform an alignment step after laying out vbases.
2426  // In 32-bit mode we do not. The check to see if we need to perform alignment
2427  // checks the RequiredAlignment field and performs alignment if it isn't 0.
2428  RequiredAlignment = Context.getTargetInfo().getTriple().isArch64Bit()
2429  ? CharUnits::One()
2430  : CharUnits::Zero();
2431  // Compute the maximum field alignment.
2432  MaxFieldAlignment = CharUnits::Zero();
2433  // Honor the default struct packing maximum alignment flag.
2434  if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct)
2435  MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
2436  // Honor the packing attribute. The MS-ABI ignores pragma pack if its larger
2437  // than the pointer size.
2438  if (const MaxFieldAlignmentAttr *MFAA = RD->getAttr<MaxFieldAlignmentAttr>()){
2439  unsigned PackedAlignment = MFAA->getAlignment();
2440  if (PackedAlignment <= Context.getTargetInfo().getPointerWidth(0))
2441  MaxFieldAlignment = Context.toCharUnitsFromBits(PackedAlignment);
2442  }
2443  // Packed attribute forces max field alignment to be 1.
2444  if (RD->hasAttr<PackedAttr>())
2445  MaxFieldAlignment = CharUnits::One();
2446 
2447  // Try to respect the external layout if present.
2448  UseExternalLayout = false;
2449  if (ExternalASTSource *Source = Context.getExternalSource())
2450  UseExternalLayout = Source->layoutRecordType(
2451  RD, External.Size, External.Align, External.FieldOffsets,
2452  External.BaseOffsets, External.VirtualBaseOffsets);
2453 }
2454 
2455 void
2456 MicrosoftRecordLayoutBuilder::initializeCXXLayout(const CXXRecordDecl *RD) {
2457  EndsWithZeroSizedObject = false;
2458  LeadsWithZeroSizedBase = false;
2459  HasOwnVFPtr = false;
2460  HasVBPtr = false;
2461  PrimaryBase = nullptr;
2462  SharedVBPtrBase = nullptr;
2463  // Calculate pointer size and alignment. These are used for vfptr and vbprt
2464  // injection.
2465  PointerInfo.Size =
2466  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
2467  PointerInfo.Alignment =
2468  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
2469  // Respect pragma pack.
2470  if (!MaxFieldAlignment.isZero())
2471  PointerInfo.Alignment = std::min(PointerInfo.Alignment, MaxFieldAlignment);
2472 }
2473 
2474 void
2475 MicrosoftRecordLayoutBuilder::layoutNonVirtualBases(const CXXRecordDecl *RD) {
2476  // The MS-ABI lays out all bases that contain leading vfptrs before it lays
2477  // out any bases that do not contain vfptrs. We implement this as two passes
2478  // over the bases. This approach guarantees that the primary base is laid out
2479  // first. We use these passes to calculate some additional aggregated
2480  // information about the bases, such as required alignment and the presence of
2481  // zero sized members.
2482  const ASTRecordLayout *PreviousBaseLayout = nullptr;
2483  // Iterate through the bases and lay out the non-virtual ones.
2484  for (const CXXBaseSpecifier &Base : RD->bases()) {
2485  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2486  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2487  // Mark and skip virtual bases.
2488  if (Base.isVirtual()) {
2489  HasVBPtr = true;
2490  continue;
2491  }
2492  // Check for a base to share a VBPtr with.
2493  if (!SharedVBPtrBase && BaseLayout.hasVBPtr()) {
2494  SharedVBPtrBase = BaseDecl;
2495  HasVBPtr = true;
2496  }
2497  // Only lay out bases with extendable VFPtrs on the first pass.
2498  if (!BaseLayout.hasExtendableVFPtr())
2499  continue;
2500  // If we don't have a primary base, this one qualifies.
2501  if (!PrimaryBase) {
2502  PrimaryBase = BaseDecl;
2503  LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
2504  }
2505  // Lay out the base.
2506  layoutNonVirtualBase(RD, BaseDecl, BaseLayout, PreviousBaseLayout);
2507  }
2508  // Figure out if we need a fresh VFPtr for this class.
2509  if (!PrimaryBase && RD->isDynamicClass())
2511  e = RD->method_end();
2512  !HasOwnVFPtr && i != e; ++i)
2513  HasOwnVFPtr = i->isVirtual() && i->size_overridden_methods() == 0;
2514  // If we don't have a primary base then we have a leading object that could
2515  // itself lead with a zero-sized object, something we track.
2516  bool CheckLeadingLayout = !PrimaryBase;
2517  // Iterate through the bases and lay out the non-virtual ones.
2518  for (const CXXBaseSpecifier &Base : RD->bases()) {
2519  if (Base.isVirtual())
2520  continue;
2521  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2522  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2523  // Only lay out bases without extendable VFPtrs on the second pass.
2524  if (BaseLayout.hasExtendableVFPtr()) {
2525  VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
2526  continue;
2527  }
2528  // If this is the first layout, check to see if it leads with a zero sized
2529  // object. If it does, so do we.
2530  if (CheckLeadingLayout) {
2531  CheckLeadingLayout = false;
2532  LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
2533  }
2534  // Lay out the base.
2535  layoutNonVirtualBase(RD, BaseDecl, BaseLayout, PreviousBaseLayout);
2536  VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
2537  }
2538  // Set our VBPtroffset if we know it at this point.
2539  if (!HasVBPtr)
2540  VBPtrOffset = CharUnits::fromQuantity(-1);
2541  else if (SharedVBPtrBase) {
2542  const ASTRecordLayout &Layout = Context.getASTRecordLayout(SharedVBPtrBase);
2543  VBPtrOffset = Bases[SharedVBPtrBase] + Layout.getVBPtrOffset();
2544  }
2545 }
2546 
2547 static bool recordUsesEBO(const RecordDecl *RD) {
2548  if (!isa<CXXRecordDecl>(RD))
2549  return false;
2550  if (RD->hasAttr<EmptyBasesAttr>())
2551  return true;
2552  if (auto *LVA = RD->getAttr<LayoutVersionAttr>())
2553  // TODO: Double check with the next version of MSVC.
2554  if (LVA->getVersion() <= LangOptions::MSVC2015)
2555  return false;
2556  // TODO: Some later version of MSVC will change the default behavior of the
2557  // compiler to enable EBO by default. When this happens, we will need an
2558  // additional isCompatibleWithMSVC check.
2559  return false;
2560 }
2561 
2562 void MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(
2563  const CXXRecordDecl *RD,
2564  const CXXRecordDecl *BaseDecl,
2565  const ASTRecordLayout &BaseLayout,
2566  const ASTRecordLayout *&PreviousBaseLayout) {
2567  // Insert padding between two bases if the left first one is zero sized or
2568  // contains a zero sized subobject and the right is zero sized or one leads
2569  // with a zero sized base.
2570  bool MDCUsesEBO = recordUsesEBO(RD);
2571  if (PreviousBaseLayout && PreviousBaseLayout->endsWithZeroSizedObject() &&
2572  BaseLayout.leadsWithZeroSizedBase() && !MDCUsesEBO)
2573  Size++;
2574  ElementInfo Info = getAdjustedElementInfo(BaseLayout);
2575  CharUnits BaseOffset;
2576 
2577  // Respect the external AST source base offset, if present.
2578  bool FoundBase = false;
2579  if (UseExternalLayout) {
2580  FoundBase = External.getExternalNVBaseOffset(BaseDecl, BaseOffset);
2581  if (FoundBase) {
2582  assert(BaseOffset >= Size && "base offset already allocated");
2583  Size = BaseOffset;
2584  }
2585  }
2586 
2587  if (!FoundBase) {
2588  if (MDCUsesEBO && BaseDecl->isEmpty() &&
2589  BaseLayout.getNonVirtualSize() == CharUnits::Zero()) {
2590  BaseOffset = CharUnits::Zero();
2591  } else {
2592  // Otherwise, lay the base out at the end of the MDC.
2593  BaseOffset = Size = Size.alignTo(Info.Alignment);
2594  }
2595  }
2596  Bases.insert(std::make_pair(BaseDecl, BaseOffset));
2597  Size += BaseLayout.getNonVirtualSize();
2598  PreviousBaseLayout = &BaseLayout;
2599 }
2600 
2601 void MicrosoftRecordLayoutBuilder::layoutFields(const RecordDecl *RD) {
2602  LastFieldIsNonZeroWidthBitfield = false;
2603  for (const FieldDecl *Field : RD->fields())
2604  layoutField(Field);
2605 }
2606 
2607 void MicrosoftRecordLayoutBuilder::layoutField(const FieldDecl *FD) {
2608  if (FD->isBitField()) {
2609  layoutBitField(FD);
2610  return;
2611  }
2612  LastFieldIsNonZeroWidthBitfield = false;
2613  ElementInfo Info = getAdjustedElementInfo(FD);
2614  Alignment = std::max(Alignment, Info.Alignment);
2615  if (IsUnion) {
2616  placeFieldAtOffset(CharUnits::Zero());
2617  Size = std::max(Size, Info.Size);
2618  } else {
2619  CharUnits FieldOffset;
2620  if (UseExternalLayout) {
2621  FieldOffset =
2622  Context.toCharUnitsFromBits(External.getExternalFieldOffset(FD));
2623  assert(FieldOffset >= Size && "field offset already allocated");
2624  } else {
2625  FieldOffset = Size.alignTo(Info.Alignment);
2626  }
2627  placeFieldAtOffset(FieldOffset);
2628  Size = FieldOffset + Info.Size;
2629  }
2630 }
2631 
2632 void MicrosoftRecordLayoutBuilder::layoutBitField(const FieldDecl *FD) {
2633  unsigned Width = FD->getBitWidthValue(Context);
2634  if (Width == 0) {
2635  layoutZeroWidthBitField(FD);
2636  return;
2637  }
2638  ElementInfo Info = getAdjustedElementInfo(FD);
2639  // Clamp the bitfield to a containable size for the sake of being able
2640  // to lay them out. Sema will throw an error.
2641  if (Width > Context.toBits(Info.Size))
2642  Width = Context.toBits(Info.Size);
2643  // Check to see if this bitfield fits into an existing allocation. Note:
2644  // MSVC refuses to pack bitfields of formal types with different sizes
2645  // into the same allocation.
2646  if (!IsUnion && LastFieldIsNonZeroWidthBitfield &&
2647  CurrentBitfieldSize == Info.Size && Width <= RemainingBitsInField) {
2648  placeFieldAtBitOffset(Context.toBits(Size) - RemainingBitsInField);
2649  RemainingBitsInField -= Width;
2650  return;
2651  }
2652  LastFieldIsNonZeroWidthBitfield = true;
2653  CurrentBitfieldSize = Info.Size;
2654  if (IsUnion) {
2655  placeFieldAtOffset(CharUnits::Zero());
2656  Size = std::max(Size, Info.Size);
2657  // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
2658  } else {
2659  // Allocate a new block of memory and place the bitfield in it.
2660  CharUnits FieldOffset = Size.alignTo(Info.Alignment);
2661  placeFieldAtOffset(FieldOffset);
2662  Size = FieldOffset + Info.Size;
2663  Alignment = std::max(Alignment, Info.Alignment);
2664  RemainingBitsInField = Context.toBits(Info.Size) - Width;
2665  }
2666 }
2667 
2668 void
2669 MicrosoftRecordLayoutBuilder::layoutZeroWidthBitField(const FieldDecl *FD) {
2670  // Zero-width bitfields are ignored unless they follow a non-zero-width
2671  // bitfield.
2672  if (!LastFieldIsNonZeroWidthBitfield) {
2673  placeFieldAtOffset(IsUnion ? CharUnits::Zero() : Size);
2674  // TODO: Add a Sema warning that MS ignores alignment for zero
2675  // sized bitfields that occur after zero-size bitfields or non-bitfields.
2676  return;
2677  }
2678  LastFieldIsNonZeroWidthBitfield = false;
2679  ElementInfo Info = getAdjustedElementInfo(FD);
2680  if (IsUnion) {
2681  placeFieldAtOffset(CharUnits::Zero());
2682  Size = std::max(Size, Info.Size);
2683  // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
2684  } else {
2685  // Round up the current record size to the field's alignment boundary.
2686  CharUnits FieldOffset = Size.alignTo(Info.Alignment);
2687  placeFieldAtOffset(FieldOffset);
2688  Size = FieldOffset;
2689  Alignment = std::max(Alignment, Info.Alignment);
2690  }
2691 }
2692 
2693 void MicrosoftRecordLayoutBuilder::injectVBPtr(const CXXRecordDecl *RD) {
2694  if (!HasVBPtr || SharedVBPtrBase)
2695  return;
2696  // Inject the VBPointer at the injection site.
2697  CharUnits InjectionSite = VBPtrOffset;
2698  // But before we do, make sure it's properly aligned.
2699  VBPtrOffset = VBPtrOffset.alignTo(PointerInfo.Alignment);
2700  // Shift everything after the vbptr down, unless we're using an external
2701  // layout.
2702  if (UseExternalLayout)
2703  return;
2704  // Determine where the first field should be laid out after the vbptr.
2705  CharUnits FieldStart = VBPtrOffset + PointerInfo.Size;
2706  // Make sure that the amount we push the fields back by is a multiple of the
2707  // alignment.
2708  CharUnits Offset = (FieldStart - InjectionSite)
2709  .alignTo(std::max(RequiredAlignment, Alignment));
2710  Size += Offset;
2711  for (uint64_t &FieldOffset : FieldOffsets)
2712  FieldOffset += Context.toBits(Offset);
2713  for (BaseOffsetsMapTy::value_type &Base : Bases)
2714  if (Base.second >= InjectionSite)
2715  Base.second += Offset;
2716 }
2717 
2718 void MicrosoftRecordLayoutBuilder::injectVFPtr(const CXXRecordDecl *RD) {
2719  if (!HasOwnVFPtr)
2720  return;
2721  // Make sure that the amount we push the struct back by is a multiple of the
2722  // alignment.
2723  CharUnits Offset =
2724  PointerInfo.Size.alignTo(std::max(RequiredAlignment, Alignment));
2725  // Push back the vbptr, but increase the size of the object and push back
2726  // regular fields by the offset only if not using external record layout.
2727  if (HasVBPtr)
2728  VBPtrOffset += Offset;
2729 
2730  if (UseExternalLayout)
2731  return;
2732 
2733  Size += Offset;
2734 
2735  // If we're using an external layout, the fields offsets have already
2736  // accounted for this adjustment.
2737  for (uint64_t &FieldOffset : FieldOffsets)
2738  FieldOffset += Context.toBits(Offset);
2739  for (BaseOffsetsMapTy::value_type &Base : Bases)
2740  Base.second += Offset;
2741 }
2742 
2743 void MicrosoftRecordLayoutBuilder::layoutVirtualBases(const CXXRecordDecl *RD) {
2744  if (!HasVBPtr)
2745  return;
2746  // Vtordisps are always 4 bytes (even in 64-bit mode)
2747  CharUnits VtorDispSize = CharUnits::fromQuantity(4);
2748  CharUnits VtorDispAlignment = VtorDispSize;
2749  // vtordisps respect pragma pack.
2750  if (!MaxFieldAlignment.isZero())
2751  VtorDispAlignment = std::min(VtorDispAlignment, MaxFieldAlignment);
2752  // The alignment of the vtordisp is at least the required alignment of the
2753  // entire record. This requirement may be present to support vtordisp
2754  // injection.
2755  for (const CXXBaseSpecifier &VBase : RD->vbases()) {
2756  const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
2757  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2758  RequiredAlignment =
2759  std::max(RequiredAlignment, BaseLayout.getRequiredAlignment());
2760  }
2761  VtorDispAlignment = std::max(VtorDispAlignment, RequiredAlignment);
2762  // Compute the vtordisp set.
2763  llvm::SmallPtrSet<const CXXRecordDecl *, 2> HasVtorDispSet;
2764  computeVtorDispSet(HasVtorDispSet, RD);
2765  // Iterate through the virtual bases and lay them out.
2766  const ASTRecordLayout *PreviousBaseLayout = nullptr;
2767  for (const CXXBaseSpecifier &VBase : RD->vbases()) {
2768  const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
2769  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2770  bool HasVtordisp = HasVtorDispSet.count(BaseDecl) > 0;
2771  // Insert padding between two bases if the left first one is zero sized or
2772  // contains a zero sized subobject and the right is zero sized or one leads
2773  // with a zero sized base. The padding between virtual bases is 4
2774  // bytes (in both 32 and 64 bits modes) and always involves rounding up to
2775  // the required alignment, we don't know why.
2776  if ((PreviousBaseLayout && PreviousBaseLayout->endsWithZeroSizedObject() &&
2777  BaseLayout.leadsWithZeroSizedBase() && !recordUsesEBO(RD)) ||
2778  HasVtordisp) {
2779  Size = Size.alignTo(VtorDispAlignment) + VtorDispSize;
2780  Alignment = std::max(VtorDispAlignment, Alignment);
2781  }
2782  // Insert the virtual base.
2783  ElementInfo Info = getAdjustedElementInfo(BaseLayout);
2784  CharUnits BaseOffset;
2785 
2786  // Respect the external AST source base offset, if present.
2787  bool FoundBase = false;
2788  if (UseExternalLayout) {
2789  FoundBase = External.getExternalVBaseOffset(BaseDecl, BaseOffset);
2790  if (FoundBase)
2791  assert(BaseOffset >= Size && "base offset already allocated");
2792  }
2793  if (!FoundBase)
2794  BaseOffset = Size.alignTo(Info.Alignment);
2795 
2796  VBases.insert(std::make_pair(BaseDecl,
2797  ASTRecordLayout::VBaseInfo(BaseOffset, HasVtordisp)));
2798  Size = BaseOffset + BaseLayout.getNonVirtualSize();
2799  PreviousBaseLayout = &BaseLayout;
2800  }
2801 }
2802 
2803 void MicrosoftRecordLayoutBuilder::finalizeLayout(const RecordDecl *RD) {
2804  // Respect required alignment. Note that in 32-bit mode Required alignment
2805  // may be 0 and cause size not to be updated.
2806  DataSize = Size;
2807  if (!RequiredAlignment.isZero()) {
2808  Alignment = std::max(Alignment, RequiredAlignment);
2809  auto RoundingAlignment = Alignment;
2810  if (!MaxFieldAlignment.isZero())
2811  RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
2812  RoundingAlignment = std::max(RoundingAlignment, RequiredAlignment);
2813  Size = Size.alignTo(RoundingAlignment);
2814  }
2815  if (Size.isZero()) {
2816  if (!recordUsesEBO(RD) || !cast<CXXRecordDecl>(RD)->isEmpty()) {
2817  EndsWithZeroSizedObject = true;
2818  LeadsWithZeroSizedBase = true;
2819  }
2820  // Zero-sized structures have size equal to their alignment if a
2821  // __declspec(align) came into play.
2822  if (RequiredAlignment >= MinEmptyStructSize)
2823  Size = Alignment;
2824  else
2825  Size = MinEmptyStructSize;
2826  }
2827 
2828  if (UseExternalLayout) {
2829  Size = Context.toCharUnitsFromBits(External.Size);
2830  if (External.Align)
2831  Alignment = Context.toCharUnitsFromBits(External.Align);
2832  }
2833 }
2834 
2835 // Recursively walks the non-virtual bases of a class and determines if any of
2836 // them are in the bases with overridden methods set.
2837 static bool
2838 RequiresVtordisp(const llvm::SmallPtrSetImpl<const CXXRecordDecl *> &
2839  BasesWithOverriddenMethods,
2840  const CXXRecordDecl *RD) {
2841  if (BasesWithOverriddenMethods.count(RD))
2842  return true;
2843  // If any of a virtual bases non-virtual bases (recursively) requires a
2844  // vtordisp than so does this virtual base.
2845  for (const CXXBaseSpecifier &Base : RD->bases())
2846  if (!Base.isVirtual() &&
2847  RequiresVtordisp(BasesWithOverriddenMethods,
2848  Base.getType()->getAsCXXRecordDecl()))
2849  return true;
2850  return false;
2851 }
2852 
2853 void MicrosoftRecordLayoutBuilder::computeVtorDispSet(
2854  llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtordispSet,
2855  const CXXRecordDecl *RD) const {
2856  // /vd2 or #pragma vtordisp(2): Always use vtordisps for virtual bases with
2857  // vftables.
2858  if (RD->getMSVtorDispMode() == MSVtorDispAttr::ForVFTable) {
2859  for (const CXXBaseSpecifier &Base : RD->vbases()) {
2860  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2861  const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
2862  if (Layout.hasExtendableVFPtr())
2863  HasVtordispSet.insert(BaseDecl);
2864  }
2865  return;
2866  }
2867 
2868  // If any of our bases need a vtordisp for this type, so do we. Check our
2869  // direct bases for vtordisp requirements.
2870  for (const CXXBaseSpecifier &Base : RD->bases()) {
2871  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2872  const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
2873  for (const auto &bi : Layout.getVBaseOffsetsMap())
2874  if (bi.second.hasVtorDisp())
2875  HasVtordispSet.insert(bi.first);
2876  }
2877  // We don't introduce any additional vtordisps if either:
2878  // * A user declared constructor or destructor aren't declared.
2879  // * #pragma vtordisp(0) or the /vd0 flag are in use.
2880  if ((!RD->hasUserDeclaredConstructor() && !RD->hasUserDeclaredDestructor()) ||
2881  RD->getMSVtorDispMode() == MSVtorDispAttr::Never)
2882  return;
2883  // /vd1 or #pragma vtordisp(1): Try to guess based on whether we think it's
2884  // possible for a partially constructed object with virtual base overrides to
2885  // escape a non-trivial constructor.
2886  assert(RD->getMSVtorDispMode() == MSVtorDispAttr::ForVBaseOverride);
2887  // Compute a set of base classes which define methods we override. A virtual
2888  // base in this set will require a vtordisp. A virtual base that transitively
2889  // contains one of these bases as a non-virtual base will also require a
2890  // vtordisp.
2891  llvm::SmallPtrSet<const CXXMethodDecl *, 8> Work;
2892  llvm::SmallPtrSet<const CXXRecordDecl *, 2> BasesWithOverriddenMethods;
2893  // Seed the working set with our non-destructor, non-pure virtual methods.
2894  for (const CXXMethodDecl *MD : RD->methods())
2895  if (MD->isVirtual() && !isa<CXXDestructorDecl>(MD) && !MD->isPure())
2896  Work.insert(MD);
2897  while (!Work.empty()) {
2898  const CXXMethodDecl *MD = *Work.begin();
2900  e = MD->end_overridden_methods();
2901  // If a virtual method has no-overrides it lives in its parent's vtable.
2902  if (i == e)
2903  BasesWithOverriddenMethods.insert(MD->getParent());
2904  else
2905  Work.insert(i, e);
2906  // We've finished processing this element, remove it from the working set.
2907  Work.erase(MD);
2908  }
2909  // For each of our virtual bases, check if it is in the set of overridden
2910  // bases or if it transitively contains a non-virtual base that is.
2911  for (const CXXBaseSpecifier &Base : RD->vbases()) {
2912  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2913  if (!HasVtordispSet.count(BaseDecl) &&
2914  RequiresVtordisp(BasesWithOverriddenMethods, BaseDecl))
2915  HasVtordispSet.insert(BaseDecl);
2916  }
2917 }
2918 
2919 /// getASTRecordLayout - Get or compute information about the layout of the
2920 /// specified record (struct/union/class), which indicates its size and field
2921 /// position information.
2922 const ASTRecordLayout &
2924  // These asserts test different things. A record has a definition
2925  // as soon as we begin to parse the definition. That definition is
2926  // not a complete definition (which is what isDefinition() tests)
2927  // until we *finish* parsing the definition.
2928 
2929  if (D->hasExternalLexicalStorage() && !D->getDefinition())
2930  getExternalSource()->CompleteType(const_cast<RecordDecl*>(D));
2931 
2932  D = D->getDefinition();
2933  assert(D && "Cannot get layout of forward declarations!");
2934  assert(!D->isInvalidDecl() && "Cannot get layout of invalid decl!");
2935  assert(D->isCompleteDefinition() && "Cannot layout type before complete!");
2936 
2937  // Look up this layout, if already laid out, return what we have.
2938  // Note that we can't save a reference to the entry because this function
2939  // is recursive.
2940  const ASTRecordLayout *Entry = ASTRecordLayouts[D];
2941  if (Entry) return *Entry;
2942 
2943  const ASTRecordLayout *NewEntry = nullptr;
2944 
2945  if (isMsLayout(*this)) {
2946  MicrosoftRecordLayoutBuilder Builder(*this);
2947  if (const auto *RD = dyn_cast<CXXRecordDecl>(D)) {
2948  Builder.cxxLayout(RD);
2949  NewEntry = new (*this) ASTRecordLayout(
2950  *this, Builder.Size, Builder.Alignment, Builder.RequiredAlignment,
2951  Builder.HasOwnVFPtr, Builder.HasOwnVFPtr || Builder.PrimaryBase,
2952  Builder.VBPtrOffset, Builder.DataSize, Builder.FieldOffsets,
2953  Builder.NonVirtualSize, Builder.Alignment, CharUnits::Zero(),
2954  Builder.PrimaryBase, false, Builder.SharedVBPtrBase,
2955  Builder.EndsWithZeroSizedObject, Builder.LeadsWithZeroSizedBase,
2956  Builder.Bases, Builder.VBases);
2957  } else {
2958  Builder.layout(D);
2959  NewEntry = new (*this) ASTRecordLayout(
2960  *this, Builder.Size, Builder.Alignment, Builder.RequiredAlignment,
2961  Builder.Size, Builder.FieldOffsets);
2962  }
2963  } else {
2964  if (const auto *RD = dyn_cast<CXXRecordDecl>(D)) {
2965  EmptySubobjectMap EmptySubobjects(*this, RD);
2966  ItaniumRecordLayoutBuilder Builder(*this, &EmptySubobjects);
2967  Builder.Layout(RD);
2968 
2969  // In certain situations, we are allowed to lay out objects in the
2970  // tail-padding of base classes. This is ABI-dependent.
2971  // FIXME: this should be stored in the record layout.
2972  bool skipTailPadding =
2973  mustSkipTailPadding(getTargetInfo().getCXXABI(), RD);
2974 
2975  // FIXME: This should be done in FinalizeLayout.
2976  CharUnits DataSize =
2977  skipTailPadding ? Builder.getSize() : Builder.getDataSize();
2978  CharUnits NonVirtualSize =
2979  skipTailPadding ? DataSize : Builder.NonVirtualSize;
2980  NewEntry = new (*this) ASTRecordLayout(
2981  *this, Builder.getSize(), Builder.Alignment,
2982  /*RequiredAlignment : used by MS-ABI)*/
2983  Builder.Alignment, Builder.HasOwnVFPtr, RD->isDynamicClass(),
2984  CharUnits::fromQuantity(-1), DataSize, Builder.FieldOffsets,
2985  NonVirtualSize, Builder.NonVirtualAlignment,
2986  EmptySubobjects.SizeOfLargestEmptySubobject, Builder.PrimaryBase,
2987  Builder.PrimaryBaseIsVirtual, nullptr, false, false, Builder.Bases,
2988  Builder.VBases);
2989  } else {
2990  ItaniumRecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
2991  Builder.Layout(D);
2992 
2993  NewEntry = new (*this) ASTRecordLayout(
2994  *this, Builder.getSize(), Builder.Alignment,
2995  /*RequiredAlignment : used by MS-ABI)*/
2996  Builder.Alignment, Builder.getSize(), Builder.FieldOffsets);
2997  }
2998  }
2999 
3000  ASTRecordLayouts[D] = NewEntry;
3001 
3002  if (getLangOpts().DumpRecordLayouts) {
3003  llvm::outs() << "\n*** Dumping AST Record Layout\n";
3004  DumpRecordLayout(D, llvm::outs(), getLangOpts().DumpRecordLayoutsSimple);
3005  }
3006 
3007  return *NewEntry;
3008 }
3009 
3011  if (!getTargetInfo().getCXXABI().hasKeyFunctions())
3012  return nullptr;
3013 
3014  assert(RD->getDefinition() && "Cannot get key function for forward decl!");
3015  RD = cast<CXXRecordDecl>(RD->getDefinition());
3016 
3017  // Beware:
3018  // 1) computing the key function might trigger deserialization, which might
3019  // invalidate iterators into KeyFunctions
3020  // 2) 'get' on the LazyDeclPtr might also trigger deserialization and
3021  // invalidate the LazyDeclPtr within the map itself
3022  LazyDeclPtr Entry = KeyFunctions[RD];
3023  const Decl *Result =
3024  Entry ? Entry.get(getExternalSource()) : computeKeyFunction(*this, RD);
3025 
3026  // Store it back if it changed.
3027  if (Entry.isOffset() || Entry.isValid() != bool(Result))
3028  KeyFunctions[RD] = const_cast<Decl*>(Result);
3029 
3030  return cast_or_null<CXXMethodDecl>(Result);
3031 }
3032 
3034  assert(Method == Method->getFirstDecl() &&
3035  "not working with method declaration from class definition");
3036 
3037  // Look up the cache entry. Since we're working with the first
3038  // declaration, its parent must be the class definition, which is
3039  // the correct key for the KeyFunctions hash.
3040  const auto &Map = KeyFunctions;
3041  auto I = Map.find(Method->getParent());
3042 
3043  // If it's not cached, there's nothing to do.
3044  if (I == Map.end()) return;
3045 
3046  // If it is cached, check whether it's the target method, and if so,
3047  // remove it from the cache. Note, the call to 'get' might invalidate
3048  // the iterator and the LazyDeclPtr object within the map.
3049  LazyDeclPtr Ptr = I->second;
3050  if (Ptr.get(getExternalSource()) == Method) {
3051  // FIXME: remember that we did this for module / chained PCH state?
3052  KeyFunctions.erase(Method->getParent());
3053  }
3054 }
3055 
3056 static uint64_t getFieldOffset(const ASTContext &C, const FieldDecl *FD) {
3057  const ASTRecordLayout &Layout = C.getASTRecordLayout(FD->getParent());
3058  return Layout.getFieldOffset(FD->getFieldIndex());
3059 }
3060 
3061 uint64_t ASTContext::getFieldOffset(const ValueDecl *VD) const {
3062  uint64_t OffsetInBits;
3063  if (const FieldDecl *FD = dyn_cast<FieldDecl>(VD)) {
3064  OffsetInBits = ::getFieldOffset(*this, FD);
3065  } else {
3066  const IndirectFieldDecl *IFD = cast<IndirectFieldDecl>(VD);
3067 
3068  OffsetInBits = 0;
3069  for (const NamedDecl *ND : IFD->chain())
3070  OffsetInBits += ::getFieldOffset(*this, cast<FieldDecl>(ND));
3071  }
3072 
3073  return OffsetInBits;
3074 }
3075 
3077  const ObjCImplementationDecl *ID,
3078  const ObjCIvarDecl *Ivar) const {
3079  const ObjCInterfaceDecl *Container = Ivar->getContainingInterface();
3080 
3081  // FIXME: We should eliminate the need to have ObjCImplementationDecl passed
3082  // in here; it should never be necessary because that should be the lexical
3083  // decl context for the ivar.
3084 
3085  // If we know have an implementation (and the ivar is in it) then
3086  // look up in the implementation layout.
3087  const ASTRecordLayout *RL;
3088  if (ID && declaresSameEntity(ID->getClassInterface(), Container))
3089  RL = &getASTObjCImplementationLayout(ID);
3090  else
3091  RL = &getASTObjCInterfaceLayout(Container);
3092 
3093  // Compute field index.
3094  //
3095  // FIXME: The index here is closely tied to how ASTContext::getObjCLayout is
3096  // implemented. This should be fixed to get the information from the layout
3097  // directly.
3098  unsigned Index = 0;
3099 
3100  for (const ObjCIvarDecl *IVD = Container->all_declared_ivar_begin();
3101  IVD; IVD = IVD->getNextIvar()) {
3102  if (Ivar == IVD)
3103  break;
3104  ++Index;
3105  }
3106  assert(Index < RL->getFieldCount() && "Ivar is not inside record layout!");
3107 
3108  return RL->getFieldOffset(Index);
3109 }
3110 
3111 /// getObjCLayout - Get or compute information about the layout of the
3112 /// given interface.
3113 ///
3114 /// \param Impl - If given, also include the layout of the interface's
3115 /// implementation. This may differ by including synthesized ivars.
3116 const ASTRecordLayout &
3117 ASTContext::getObjCLayout(const ObjCInterfaceDecl *D,
3118  const ObjCImplementationDecl *Impl) const {
3119  // Retrieve the definition
3120  if (D->hasExternalLexicalStorage() && !D->getDefinition())
3121  getExternalSource()->CompleteType(const_cast<ObjCInterfaceDecl*>(D));
3122  D = D->getDefinition();
3123  assert(D && D->isThisDeclarationADefinition() && "Invalid interface decl!");
3124 
3125  // Look up this layout, if already laid out, return what we have.
3126  const ObjCContainerDecl *Key =
3127  Impl ? (const ObjCContainerDecl*) Impl : (const ObjCContainerDecl*) D;
3128  if (const ASTRecordLayout *Entry = ObjCLayouts[Key])
3129  return *Entry;
3130 
3131  // Add in synthesized ivar count if laying out an implementation.
3132  if (Impl) {
3133  unsigned SynthCount = CountNonClassIvars(D);
3134  // If there aren't any synthesized ivars then reuse the interface
3135  // entry. Note we can't cache this because we simply free all
3136  // entries later; however we shouldn't look up implementations
3137  // frequently.
3138  if (SynthCount == 0)
3139  return getObjCLayout(D, nullptr);
3140  }
3141 
3142  ItaniumRecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
3143  Builder.Layout(D);
3144 
3145  const ASTRecordLayout *NewEntry =
3146  new (*this) ASTRecordLayout(*this, Builder.getSize(),
3147  Builder.Alignment,
3148  /*RequiredAlignment : used by MS-ABI)*/
3149  Builder.Alignment,
3150  Builder.getDataSize(),
3151  Builder.FieldOffsets);
3152 
3153  ObjCLayouts[Key] = NewEntry;
3154 
3155  return *NewEntry;
3156 }
3157 
3158 static void PrintOffset(raw_ostream &OS,
3159  CharUnits Offset, unsigned IndentLevel) {
3160  OS << llvm::format("%10" PRId64 " | ", (int64_t)Offset.getQuantity());
3161  OS.indent(IndentLevel * 2);
3162 }
3163 
3164 static void PrintBitFieldOffset(raw_ostream &OS, CharUnits Offset,
3165  unsigned Begin, unsigned Width,
3166  unsigned IndentLevel) {
3167  llvm::SmallString<10> Buffer;
3168  {
3169  llvm::raw_svector_ostream BufferOS(Buffer);
3170  BufferOS << Offset.getQuantity() << ':';
3171  if (Width == 0) {
3172  BufferOS << '-';
3173  } else {
3174  BufferOS << Begin << '-' << (Begin + Width - 1);
3175  }
3176  }
3177 
3178  OS << llvm::right_justify(Buffer, 10) << " | ";
3179  OS.indent(IndentLevel * 2);
3180 }
3181 
3182 static void PrintIndentNoOffset(raw_ostream &OS, unsigned IndentLevel) {
3183  OS << " | ";
3184  OS.indent(IndentLevel * 2);
3185 }
3186 
3187 static void DumpRecordLayout(raw_ostream &OS, const RecordDecl *RD,
3188  const ASTContext &C,
3189  CharUnits Offset,
3190  unsigned IndentLevel,
3191  const char* Description,
3192  bool PrintSizeInfo,
3193  bool IncludeVirtualBases) {
3194  const ASTRecordLayout &Layout = C.getASTRecordLayout(RD);
3195  auto CXXRD = dyn_cast<CXXRecordDecl>(RD);
3196 
3197  PrintOffset(OS, Offset, IndentLevel);
3198  OS << C.getTypeDeclType(const_cast<RecordDecl*>(RD)).getAsString();
3199  if (Description)
3200  OS << ' ' << Description;
3201  if (CXXRD && CXXRD->isEmpty())
3202  OS << " (empty)";
3203  OS << '\n';
3204 
3205  IndentLevel++;
3206 
3207  // Dump bases.
3208  if (CXXRD) {
3209  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
3210  bool HasOwnVFPtr = Layout.hasOwnVFPtr();
3211  bool HasOwnVBPtr = Layout.hasOwnVBPtr();
3212 
3213  // Vtable pointer.
3214  if (CXXRD->isDynamicClass() && !PrimaryBase && !isMsLayout(C)) {
3215  PrintOffset(OS, Offset, IndentLevel);
3216  OS << '(' << *RD << " vtable pointer)\n";
3217  } else if (HasOwnVFPtr) {
3218  PrintOffset(OS, Offset, IndentLevel);
3219  // vfptr (for Microsoft C++ ABI)
3220  OS << '(' << *RD << " vftable pointer)\n";
3221  }
3222 
3223  // Collect nvbases.
3225  for (const CXXBaseSpecifier &Base : CXXRD->bases()) {
3226  assert(!Base.getType()->isDependentType() &&
3227  "Cannot layout class with dependent bases.");
3228  if (!Base.isVirtual())
3229  Bases.push_back(Base.getType()->getAsCXXRecordDecl());
3230  }
3231 
3232  // Sort nvbases by offset.
3233  std::stable_sort(Bases.begin(), Bases.end(),
3234  [&](const CXXRecordDecl *L, const CXXRecordDecl *R) {
3235  return Layout.getBaseClassOffset(L) < Layout.getBaseClassOffset(R);
3236  });
3237 
3238  // Dump (non-virtual) bases
3239  for (const CXXRecordDecl *Base : Bases) {
3240  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base);
3241  DumpRecordLayout(OS, Base, C, BaseOffset, IndentLevel,
3242  Base == PrimaryBase ? "(primary base)" : "(base)",
3243  /*PrintSizeInfo=*/false,
3244  /*IncludeVirtualBases=*/false);
3245  }
3246 
3247  // vbptr (for Microsoft C++ ABI)
3248  if (HasOwnVBPtr) {
3249  PrintOffset(OS, Offset + Layout.getVBPtrOffset(), IndentLevel);
3250  OS << '(' << *RD << " vbtable pointer)\n";
3251  }
3252  }
3253 
3254  // Dump fields.
3255  uint64_t FieldNo = 0;
3256  for (RecordDecl::field_iterator I = RD->field_begin(),
3257  E = RD->field_end(); I != E; ++I, ++FieldNo) {
3258  const FieldDecl &Field = **I;
3259  uint64_t LocalFieldOffsetInBits = Layout.getFieldOffset(FieldNo);
3260  CharUnits FieldOffset =
3261  Offset + C.toCharUnitsFromBits(LocalFieldOffsetInBits);
3262 
3263  // Recursively dump fields of record type.
3264  if (auto RT = Field.getType()->getAs<RecordType>()) {
3265  DumpRecordLayout(OS, RT->getDecl(), C, FieldOffset, IndentLevel,
3266  Field.getName().data(),
3267  /*PrintSizeInfo=*/false,
3268  /*IncludeVirtualBases=*/true);
3269  continue;
3270  }
3271 
3272  if (Field.isBitField()) {
3273  uint64_t LocalFieldByteOffsetInBits = C.toBits(FieldOffset - Offset);
3274  unsigned Begin = LocalFieldOffsetInBits - LocalFieldByteOffsetInBits;
3275  unsigned Width = Field.getBitWidthValue(C);
3276  PrintBitFieldOffset(OS, FieldOffset, Begin, Width, IndentLevel);
3277  } else {
3278  PrintOffset(OS, FieldOffset, IndentLevel);
3279  }
3280  OS << Field.getType().getAsString() << ' ' << Field << '\n';
3281  }
3282 
3283  // Dump virtual bases.
3284  if (CXXRD && IncludeVirtualBases) {
3285  const ASTRecordLayout::VBaseOffsetsMapTy &VtorDisps =
3286  Layout.getVBaseOffsetsMap();
3287 
3288  for (const CXXBaseSpecifier &Base : CXXRD->vbases()) {
3289  assert(Base.isVirtual() && "Found non-virtual class!");
3290  const CXXRecordDecl *VBase = Base.getType()->getAsCXXRecordDecl();
3291 
3292  CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBase);
3293 
3294  if (VtorDisps.find(VBase)->second.hasVtorDisp()) {
3295  PrintOffset(OS, VBaseOffset - CharUnits::fromQuantity(4), IndentLevel);
3296  OS << "(vtordisp for vbase " << *VBase << ")\n";
3297  }
3298 
3299  DumpRecordLayout(OS, VBase, C, VBaseOffset, IndentLevel,
3300  VBase == Layout.getPrimaryBase() ?
3301  "(primary virtual base)" : "(virtual base)",
3302  /*PrintSizeInfo=*/false,
3303  /*IncludeVirtualBases=*/false);
3304  }
3305  }
3306 
3307  if (!PrintSizeInfo) return;
3308 
3309  PrintIndentNoOffset(OS, IndentLevel - 1);
3310  OS << "[sizeof=" << Layout.getSize().getQuantity();
3311  if (CXXRD && !isMsLayout(C))
3312  OS << ", dsize=" << Layout.getDataSize().getQuantity();
3313  OS << ", align=" << Layout.getAlignment().getQuantity();
3314 
3315  if (CXXRD) {
3316  OS << ",\n";
3317  PrintIndentNoOffset(OS, IndentLevel - 1);
3318  OS << " nvsize=" << Layout.getNonVirtualSize().getQuantity();
3319  OS << ", nvalign=" << Layout.getNonVirtualAlignment().getQuantity();
3320  }
3321  OS << "]\n";
3322 }
3323 
3325  raw_ostream &OS,
3326  bool Simple) const {
3327  if (!Simple) {
3328  ::DumpRecordLayout(OS, RD, *this, CharUnits(), 0, nullptr,
3329  /*PrintSizeInfo*/true,
3330  /*IncludeVirtualBases=*/true);
3331  return;
3332  }
3333 
3334  // The "simple" format is designed to be parsed by the
3335  // layout-override testing code. There shouldn't be any external
3336  // uses of this format --- when LLDB overrides a layout, it sets up
3337  // the data structures directly --- so feel free to adjust this as
3338  // you like as long as you also update the rudimentary parser for it
3339  // in libFrontend.
3340 
3341  const ASTRecordLayout &Info = getASTRecordLayout(RD);
3342  OS << "Type: " << getTypeDeclType(RD).getAsString() << "\n";
3343  OS << "\nLayout: ";
3344  OS << "<ASTRecordLayout\n";
3345  OS << " Size:" << toBits(Info.getSize()) << "\n";
3346  if (!isMsLayout(*this))
3347  OS << " DataSize:" << toBits(Info.getDataSize()) << "\n";
3348  OS << " Alignment:" << toBits(Info.getAlignment()) << "\n";
3349  OS << " FieldOffsets: [";
3350  for (unsigned i = 0, e = Info.getFieldCount(); i != e; ++i) {
3351  if (i) OS << ", ";
3352  OS << Info.getFieldOffset(i);
3353  }
3354  OS << "]>\n";
3355 }
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:1629
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:212
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:1257
llvm::DenseMap< const CXXRecordDecl *, VBaseInfo > VBaseOffsetsMapTy
Definition: RecordLayout.h:57
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:736
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:415
const llvm::Triple & getTriple() const
Returns the target triple of the primary target.
Definition: TargetInfo.h:781
CharUnits getBaseClassOffset(const CXXRecordDecl *Base) const
getBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:219
unsigned getNumVBases() const
Retrieves the number of virtual base classes of this class.
Definition: DeclCXX.h:751
Decl - This represents one declaration (or definition), e.g.
Definition: DeclBase.h:81
bool isPOD() const
Whether this class is a POD-type (C++ [class]p4)
Definition: DeclCXX.h:1221
unsigned getFieldIndex() const
getFieldIndex - Returns the index of this field within its record, as appropriate for passing to ASTR...
Definition: Decl.cpp:3577
const RecordDecl * getParent() const
getParent - Returns the parent of this field declaration, which is the struct in which this field is ...
Definition: Decl.h:2553
The base class of the type hierarchy.
Definition: Type.h:1300
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:2494
bool isZero() const
isZero - Test whether the quantity equals zero.
Definition: CharUnits.h:116
const TargetInfo & getTargetInfo() const
Definition: ASTContext.h:643
CharUnits getAlignment() const
getAlignment - Get the record alignment in characters.
Definition: RecordLayout.h:167
unsigned getCharWidth() const
Definition: TargetInfo.h:332
QualType getElementType() const
Definition: Type.h:2528
bool isCompleteDefinition() const
isCompleteDefinition - Return true if this decl has its body fully specified.
Definition: Decl.h:2985
bool hasVBPtr() const
hasVBPtr - Does this class have a virtual function table pointer.
Definition: RecordLayout.h:272
const T * getAs() const
Member-template getAs<specific type>&#39;.
Definition: Type.h:6052
unsigned getCharAlign() const
Definition: TargetInfo.h:333
The "__interface" keyword.
Definition: Type.h:4502
bool hasOwnVFPtr() const
hasOwnVFPtr - Does this class provide its own virtual-function table pointer, rather than inheriting ...
Definition: RecordLayout.h:246
bool isInvalidDecl() const
Definition: DeclBase.h:532
unsigned getZeroLengthBitfieldBoundary() const
Get the fixed alignment value in bits for a member that follows a zero length bitfield.
Definition: TargetInfo.h:518
bool mayInsertExtraPadding(bool EmitRemark=false) const
Whether we are allowed to insert extra padding between fields.
Definition: Decl.cpp:3924
IdentifierInfo * getIdentifier() const
getIdentifier - Get the identifier that names this declaration, if there is one.
Definition: Decl.h:232
RecordDecl - Represents a struct/union/class.
Definition: Decl.h:3379
uint64_t getPointerWidth(unsigned AddrSpace) const
Return the width of pointers on this target, for the specified address space.
Definition: TargetInfo.h:308
bool isEmpty() const
Determine whether this is an empty class in the sense of (C++11 [meta.unary.prop]).
Definition: DeclCXX.h:1236
TargetCXXABI getCXXABI() const
Get the C++ ABI currently in use.
Definition: TargetInfo.h:850
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:3498
field_range fields() const
Definition: Decl.h:3508
FieldDecl - An instance of this class is created by Sema::ActOnField to represent a member of a struc...
Definition: Decl.h:2377
bool hasUserDeclaredDestructor() const
Determine whether this class has a user-declared destructor.
Definition: DeclCXX.h:1096
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:227
method_iterator method_begin() const
Method begin iterator.
Definition: DeclCXX.h:784
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.
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:2452
ObjCContainerDecl - Represents a container for method declarations.
Definition: DeclObjC.h:919
TagKind getTagKind() const
Definition: Decl.h:3044
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:281
ArrayRef< NamedDecl * > chain() const
Definition: Decl.h:2638
std::string getAsString() const
Definition: Type.h:940
unsigned Align
Definition: ASTContext.h:118
field_iterator field_begin() const
Definition: Decl.cpp:3877
unsigned getBitWidthValue(const ASTContext &Ctx) const
Definition: Decl.cpp:3572
bool declaresSameEntity(const Decl *D1, const Decl *D2)
Determine whether two declarations declare the same entity.
Definition: DeclBase.h:1120
const VBaseOffsetsMapTy & getVBaseOffsetsMap() const
Definition: RecordLayout.h:302
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:512
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:341
CanQualType UnsignedCharTy
Definition: ASTContext.h:972
lookup_result lookup(DeclarationName Name) const
lookup - Find the declarations (if any) with the given Name in this context.
Definition: DeclBase.cpp:1507
bool hasAttr() const
Definition: DeclBase.h:521
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:1549
bool isDynamicClass() const
Definition: DeclCXX.h:714
bool useExplicitBitFieldAlignment() const
Check whether explicit bitfield alignment attributes should be.
Definition: TargetInfo.h:524
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:1365
method_iterator end_overridden_methods() const
Definition: DeclCXX.cpp:1875
QuantityType getQuantity() const
getQuantity - Get the raw integer representation of this quantity.
Definition: CharUnits.h:179
ID
Defines the address space values used by the address space qualifier of QualType. ...
Definition: AddressSpaces.h:26
const CXXMethodDecl *const * method_iterator
Definition: DeclCXX.h:2023
ASTRecordLayout - This class contains layout information for one RecordDecl, which is a struct/union/...
Definition: RecordLayout.h:34
bool isMsStruct(const ASTContext &C) const
isMsStrust - Get whether or not this is an ms_struct which can be turned on with an attribute...
Definition: Decl.cpp:3894
bool isInlineSpecified() const
Determine whether the "inline" keyword was specified for this function.
Definition: Decl.h:2151
ValueDecl - Represent the declaration of a variable (in which case it is an lvalue) a function (in wh...
Definition: Decl.h:591
SourceLocation End
bool isNearlyEmpty(const CXXRecordDecl *RD) const
field_iterator field_end() const
Definition: Decl.h:3511
#define bool
Definition: stdbool.h:31
CharUnits getSizeOfLargestEmptySubobject() const
Definition: RecordLayout.h:234
CharUnits getTypeAlignInChars(QualType T) const
Return the ABI-specified alignment of a (complete) type T, in characters.
CXXRecordDecl * getDefinition() const
Definition: DeclCXX.h:694
ObjCInterfaceDecl * getSuperClass() const
Definition: DeclObjC.cpp:314
SourceLocation Begin
const CXXRecordDecl * getPrimaryBase() const
getPrimaryBase - Get the primary base for this record.
Definition: RecordLayout.h:204
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:173
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:1427
bool isPolymorphic() const
Whether this class is polymorphic (C++ [class.virtual]), which means that the class contains or inher...
Definition: DeclCXX.h:1246
bool hasExtendableVFPtr() const
hasVFPtr - Does this class have a virtual function table pointer that can be extended by a derived cl...
Definition: RecordLayout.h:254
unsigned getMaxAlignment() const
getMaxAlignment - return the maximum alignment specified by attributes on this decl, 0 if there are none.
Definition: DeclBase.cpp:355
method_iterator method_end() const
Method past-the-end iterator.
Definition: DeclCXX.h:788
unsigned Map[FirstTargetAddressSpace]
The type of a lookup table which maps from language-specific address spaces to target-specific ones...
Definition: AddressSpaces.h:53
specific_decl_iterator< FieldDecl > field_iterator
Definition: Decl.h:3505
CharUnits getVBPtrOffset() const
getVBPtrOffset - Get the offset for virtual base table pointer.
Definition: RecordLayout.h:292
const Type * getBaseElementTypeUnsafe() const
Get the base element type of this type, potentially discarding type qualifiers.
Definition: Type.h:6010
CharUnits getRequiredAlignment() const
Definition: RecordLayout.h:277
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:1296
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:209
static bool recordUsesEBO(const RecordDecl *RD)
RecordDecl * getDecl() const
Definition: Type.h:3804
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:177
static uint64_t roundUpSizeToCharAlignment(uint64_t Size, const ASTContext &Context)
#define false
Definition: stdbool.h:33
The "struct" keyword.
Definition: Type.h:4500
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:1918
const ConstantArrayType * getAsConstantArrayType(QualType T) const
Definition: ASTContext.h:2254
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:1842
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:183
bool useBitFieldTypeAlignment() const
Check whether the alignment of bit-field types is respected when laying out structures.
Definition: TargetInfo.h:506
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:3431
ASTContext & operator=(const ASTContext &)=delete
std::pair< CharUnits, CharUnits > getTypeInfoInChars(const Type *T) const
CanQualType UnsignedShortTy
Definition: ASTContext.h:972
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:197
TagTypeKind
The kind of a tag type.
Definition: Type.h:4498
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:170
method_iterator begin_overridden_methods() const
Definition: DeclCXX.cpp:1870
IndirectFieldDecl - An instance of this class is created to represent a field injected from an anonym...
Definition: Decl.h:2619
CanQualType UnsignedLongLongTy
Definition: ASTContext.h:973
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:897
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:2033
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:1015
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:1559
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:5767
A helper class that allows the use of isa/cast/dyncast to detect TagType objects of structs/unions/cl...
Definition: Type.h:3795
unsigned getAddressSpace() const
Return the address space of this type.
Definition: Type.h:5615
CanQualType UnsignedLongTy
Definition: ASTContext.h:972
static bool RequiresVtordisp(const llvm::SmallPtrSetImpl< const CXXRecordDecl *> &BasesWithOverriddenMethods, const CXXRecordDecl *RD)
T * getAttr() const
Definition: DeclBase.h:518
uint64_t getCharWidth() const
Return the size of the character type, in bits.
Definition: ASTContext.h:1947
void setNonKeyFunction(const CXXMethodDecl *method)
Observe that the given method cannot be a key function.
Base for LValueReferenceType and RValueReferenceType.
Definition: Type.h:2357
The "class" keyword.
Definition: Type.h:4506
Represents a base class of a C++ class.
Definition: DeclCXX.h:157
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:1943
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:266
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:189
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:2081
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
uint64_t getPointerAlign(unsigned AddrSpace) const
Definition: TargetInfo.h:311
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:237
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:3053
CharUnits getTypeSizeInChars(QualType T) const
Return the size of the specified (complete) type T, in characters.
QualType getType() const
Definition: Decl.h:600
NamedDecl - This represents a decl with a name.
Definition: Decl.h:213
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:266
const LangOptions & getLangOpts() const
Definition: ASTContext.h:659
Represents the canonical version of C arrays with a specified constant size.
Definition: Type.h:2550
base_class_range vbases()
Definition: DeclCXX.h:753
SourceLocation getLocation() const
Definition: DeclBase.h:407
bool isExternallyVisible() const
Definition: Decl.h:338
CanQualType UnsignedIntTy
Definition: ASTContext.h:972
bool leadsWithZeroSizedBase() const
Definition: RecordLayout.h:285
method_range methods() const
Definition: DeclCXX.h:778